Temporal persistence of unidirectional rhythmic coupling is inversely associated with salivary oxytocin change during facilitated drum circles in children

Temporal persistence of unidirectional rhythmic coupling is inversely associated with salivary oxytocin change during facilitated drum circles in children | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Temporal persistence of unidirectional rhythmic coupling is inversely associated with salivary oxytocin change during facilitated drum circles in children Mitsuru Kikuchi, Yuko Yoshimura, Sanae Tanaka, Yuri Okanemasa, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9139008/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Facilitated drum circles may promote social bonding in children, yet endocrine responses vary widely. In a school-based pilot study (n = 11; aged 9–10 years), we examined whether the temporal structure of facilitator–child rhythmic interaction relates to pre–post changes in salivary oxytocin. Chest-mounted accelerometry (20 Hz) from the facilitator and each child during a 30-min drum circle was decomposed into a rhythm band (0.3–3 Hz) and a beat-related component. We estimated time-resolved directed coupling using transfer entropy (60-s windows, 5-s step) and computed directional asymmetry (ΔTE). Salivary oxytocin increased from pre to post (paired t-test, two-sided, p = 0.022), while cortisol showed no significant change. Individual oxytocin change was not strongly related to conventional summary indices of directional influence. Instead, oxytocin change was inversely associated with the longest sustained episode of significant unidirectional rhythmic influence (Spearman ρ = −0.72, p = 0.013). These exploratory findings suggest that prolonged unidirectional lock-in at the rhythmic timescale may be less conducive to oxytocin increases than dynamically shifting, bidirectional exchange. Larger preregistered studies are needed to determine whether temporal persistence of directional coupling provides a biologically relevant marker of engagement during group music-making. Biological sciences/Neuroscience Biological sciences/Physiology Biological sciences/Psychology Social science/Psychology Directional coupling Drum circle Interpersonal synchrony Oxytocin Rhythmic interaction Transfer entropy Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Participatory arts-based activities are increasingly recognized as scalable approaches to support children’s mental health and social connectedness 1 , 2 . Facilitated drum circles are a prominent example because they combine accessible music-making with inherently interactive, reciprocity-like rhythmic exchange—shared timing, imitation, and turn-taking—within a group setting 3 – 5 . Evaluations of drumming-based programs suggest potential benefits for social and emotional functioning in young people 4 , 5 , while work in adult or clinical populations indicates that group drumming can modulate biological markers relevant to stress- and health-related processes 3 , 6 . However, the specific within-session interaction dynamics that may relate to children’s neuroendocrine responses, including salivary oxytocin, remain insufficiently characterized. A plausible candidate mechanism linking rhythmic social activity to socioemotional outcomes is the oxytocin system. Oxytocin (OT) is a neuropeptide implicated in social approach, affiliative behavior, and context-dependent modulation of socioemotional processes 7 – 9 . Importantly, contemporary accounts emphasize that OT effects are not uniformly “prosocial,” but are shaped by situational demands and individual factors, including social context and perceived salience of cues 8 , 9 . In parallel, the hypothalamic–pituitary–adrenal (HPA) axis, indexed peripherally by cortisol (CORT), is responsive to stress, arousal, and social-evaluative processes; salivary CORT is commonly used as a noninvasive marker in psychoneuroendocrine research 10 . Studying OT and CORT together may therefore help distinguish endocrine signatures related to social engagement versus arousal/stress-related activation during group activities. A second line of evidence motivating the present work comes from research on interpersonal synchrony. Coordinated timing between individuals—via movement, vocalization, or joint action—can increase affiliation and cooperation 11 – 13 , including in early development 14 . Meta-analytic work supports small-to-moderate prosocial effects of synchrony across tasks, with substantial heterogeneity 15 . In the context of music and rhythm, theories propose that synchronized activities may promote social bonding via mechanisms such as “self–other merging,” shared prediction, and neurochemical modulation, including endorphin-related pathways 16 , 17 . Consistent with endocrine involvement, salivary OT has been reported to show context-sensitive changes during socially engaging vocal or musical activities (e.g., social vocalizations), and singing-related effects may differ by performance format (e.g., choir versus solo singing), sometimes alongside changes in CORT and mood 18 , 19 .Experimental work further suggests that OT responses during sensorimotor synchronization can depend on social feedback and participant factors 20 , underscoring the importance of interaction context; related intervention work in vulnerable child populations also supports the sensitivity of salivary OT to socially structured rhythmic activity 21 . Recently, we reported that facilitated drum circle participation can be accompanied by changes in salivary OT in children, and that pre-existing social relationships may modulate this response, with increases being more evident when the activity is shared with friends than with strangers 22 . That study was conducted in a laboratory setting and focused on group-level endocrine changes and between-group differences. However, a key unresolved question is why endocrine responses vary substantially between children even within a shared session. Most prior work on synchrony and group music has relied on undirected coupling measures (e.g., correlation, phase-locking), which quantify similarity or coordination strength but do not directly capture who influences whom over time. In interactive rhythmic settings, communication-like processes may depend not only on coordination strength but also on the directionality and temporal organization of influence—whether interactions become prolonged in one directional mode or remain mutually adaptive. To quantify directional interaction structure, information-theoretic approaches such as transfer entropy (TE) provide a model-free estimate of directed predictive influence between time series 23 , 24 . TE has been applied to characterize behavioral roles and leader–follower dynamics in rhythmic dyadic interaction 25 , 26 , and to describe directed coordination in group drumming contexts 27 . In musical joint action, leadership can also manifest in movement dynamics such as body sway, suggesting that directional aspects of coordination may be behaviorally meaningful beyond overt turn-taking 28 . Building on these ideas, we examined TE-based directional dynamics between a facilitator and each child during a school-based drum circle, while explicitly separating movement into frequency layers: a slow rhythm band (capturing ongoing rhythmic coordination) and a beat-related component emphasizing event-like movements (such as striking or transient timing adjustments). We further introduced a temporal-structure metric, Max_block_s, indexing the longest sustained significant unidirectional TE episode, as a candidate marker of reduced reciprocal adaptation. In this exploratory pilot study, our primary aim was to test whether directional interaction structure, particularly the temporal persistence of unidirectional rhythmic influence, covaries with individual differences in salivary OT change during drum circle participation. Secondarily, we explored whether beat-related interaction variability might relate to CORT change, consistent with the possibility that different frequency layers reflect partially distinct psychophysiological processes. Given the small sample size and single-session design, analyses were framed as exploratory and effect-size–oriented rather than confirmatory. Results Participant and data overview Eleven children provided usable pre–post saliva samples and analyzable accelerometry recordings during a school-based facilitated drum circle session (Fig. 1 ). Hormone concentrations were log-transformed before computing pre–post change indices due to typical right-skew in salivary endocrine measures (see Methods). Summary descriptive statistics for OT and CORT (pre and post) are reported in Table 1 . Table 1 Pre–post salivary endocrine concentrations (log10-transformed) during drum circle participation in children (n = 11). Measure Pre mean (SD) Post mean (SD) t (df = 10) p (two-sided) Oxytocin (log10) 2.040 (0.370) 2.246 (0.260) 2.71 0.022 Cortisol (log10) −0.906 (0.134) −0.828 (0.281) 1.15 0.275 Group-level endocrine changes (Fig. 2) Salivary OT increased at the group level from pre- to post-session (paired t-test, t(10) = 2.71, p = 0.022; Table 1 ), consistent with prior work showing that facilitated drum circles can elicit salivary OT increases in children under specific social conditions, particularly when the activity is shared with friends 22 . In contrast, salivary CORT did not show a significant pre–post change at the group level (paired t-test, two-sided, t(10) = 1.15, p = 0.275) and exhibited only a small upward trend. Directional interaction dynamics differ between rhythm- and beat-related movement components To characterize how facilitator–child interaction unfolded over time, we computed windowed TE in two movement components derived from tri-axial accelerometry: a rhythm band (0.3–3 Hz) capturing slower rhythmic body coordination and a beat-related component derived from jerk-based event-like movement changes (Methods). For each dyad, we quantified directional asymmetry as ΔTE(t) = TE(Fac→i) − TE(i→Fac) and visualized its temporal evolution using heatmaps (Fig. 3 a–b), where circles indicate windows significant relative to a two-sided circular-shift surrogate test (200 surrogates, α = 0.05). Across children, rhythm-band ΔTE(t) showed pronounced time-varying structure with intermittent significant episodes and participant-specific patterns, consistent with dynamic adjustment processes at the rhythmic level. In contrast, the beat-related component showed a distinct interaction signature, consistent with more event-structured coordination. These frequency-layer–dependent patterns motivated subsequent individual-differences analyses linking interaction structure to endocrine changes. Rhythm-band interaction structure is associated with oxytocin change We next examined whether individual differences in OT change were related to TE-derived features in the rhythm band (Table 2 ). Several previously used directional indices showed moderate, non-significant associations with OT change in this pilot sample (e.g., P_sig_pos: ρ = −0.523, p = 0.099; SD_dTE: ρ = −0.473, p = 0.142; n = 11). Table 2. Individual-level TE-derived directional interaction metrics and their associations with endocrine change in children (n = 11). Spearman rank correlations are reported between selected TE metrics and log-transformed endocrine change (ΔOT_log, ΔCORT_log). a. Rhythm-band interaction metrics Metric ρ (ΔOT_log) p ρ (ΔCORT_log) p P_sig_pos −0.523 0.099 −0.128 0.707 P_sig_neg −0.196 0.564 0.401 0.222 Reciprocity 0.318 0.340 0.155 0.650 SD_dTE −0.473 0.142 0.382 0.247 Switch_rate_per_min −0.229 0.499 −0.326 0.327 Max_block_s −0.720 0.013* −0.132 0.699 *P < 0.05 Sensitivity analysis excluding the participant with the largest Max_block_s value (ID No.5, 200 s): Max_block_s vs ΔOT_log → ρ = −0.626, p = 0.053 (n = 10). b. Beat-related metrics Metric ρ (ΔOT_log) p ρ (ΔCORT_log) p P_sig_pos −0.155 0.650 0.391 0.235 P_sig_neg 0.383 0.245 0.200 0.555 Reciprocity 0.091 0.790 −0.345 0.298 SD_dTE −0.500 0.117 0.509 0.110 Switch_rate_per_min 0.314 0.347 0.333 0.318 Max_block_s 0.446 0.169 0.326 0.327 c. LayerDiff (Rhythm−Beat) metrics Metric ρ (ΔOT_log) p ρ (ΔCORT_log) p P_sig_pos -0.232 0.492 -0.451 0.164 P_sig_neg -0.464 0.151 0.191 0.574 Reciprocity -0.009 0.979 0.409 0.212 SD_dTE -0.264 0.433 0.273 0.417 Switch_rate_per_min -0.269 0.424 -0.419 0.199 Max_block_s -0.729 0.011* -0.087 0.8 *P < 0.05 Note . TE-derived directional interaction metrics and associations with endocrine change. Individual-level summary metrics derived from windowed transfer entropy (TE) analyses were computed separately for rhythm-band (0.3–3 Hz) and beat-related movement components. In panel c, cross-layer difference metrics were defined as the rhythm-band value minus the corresponding beat-related value for each metric. Metrics include the proportion of significant facilitator-to-child influence (P_sig_pos), proportion of significant child-to-facilitator influence (P_sig_neg), reciprocity-like indices, variability of directional asymmetry (SD_dTE), switching rate of significant directional states, and maximum sustained unidirectional episode duration (Max_block_s). Spearman correlations with log-transformed oxytocin (ΔOT_log) and cortisol (ΔCORT_log) changes are shown. A sensitivity analysis excluding the participant with the largest Max_block_s value is reported for transparency. In contrast, Max_block_s—the maximum duration (seconds) of a sustained significant unidirectional ΔTE episode in the rhythm band—showed a strong negative association with OT change (Spearman ρ = −0.720, p = 0.013; n = 11; Fig. 4 ). Thus, children exhibiting longer sustained unidirectional rhythmic influence (in either direction) tended to show smaller OT increases (or decreases) from pre to post. Sensitivity analysis for an influential observation To evaluate robustness to an influential observation, we examined the child with the largest Max_block_s value (ID: No.5; Max_block_s = 200 s), who also showed a decrease in OT (ΔOT_log = − 0.130). Excluding this child (n = 10) yielded a similar-magnitude negative association with reduced precision (Spearman ρ = −0.626, p = 0.053). These results suggest that the observed relationship is not solely driven by a single data point, while also highlighting the uncertainty inherent in small samples. Exploratory cross-layer analyses and associations with cortisol Exploratory cross-layer analyses yielded two preliminary patterns (Table 2 c). First, the rhythm-minus-beat difference in Max_block_s showed a strong negative association with ΔOT_log (ρ = −0.729, p = 0.011; n = 11), indicating that larger rhythm–beat separation in sustained unidirectional episode duration was associated with smaller OT increases. Second, beat-band SD_dTE showed a moderate positive association with ΔCORT_log (ρ = 0.509, p = 0.110; n = 11), which attenuated after excluding the influential observation (ρ = 0.350). The rhythm-minus-beat difference in the positive-direction significance proportion (P_sig_pos) also showed a moderate negative association with ΔCORT_log (ρ = −0.451, p = 0.164), but bootstrap uncertainty for this association was substantial (95% CI: −0.617 to 0.611), indicating low precision in this pilot dataset (Supplementary Methods). These cross-layer results are exploratory and should be interpreted primarily as targets for replication. Discussion In this school-based exploratory study of children participating in a facilitated drum circle, we observed two main findings. First, salivary OT increased at the group level from pre to post participation, broadly consistent with prior work showing that facilitated drum circles can elicit salivary OT increases in children under specific social conditions, particularly when the activity is shared with friends 22. Second, and centrally, individual differences in OT change were most strongly associated not with the overall magnitude of directional influence, but with the temporal persistence of unidirectional rhythmic influence captured by Max_block_s. Children who exhibited longer sustained significant unidirectional influence episodes in the rhythm band tended to show smaller OT increases (or decreases). This pattern supports the broader idea that in interactive rhythmic contexts, endocrine variability may relate to how influence is organized over time, rather than to influence strength alone. Most prior movement-synchrony studies emphasize coupling strength (e.g., correlation, phase synchrony), which captures similarity but not the directional organization of interaction. Yet interactive communication-like processes often involve ongoing mutual adjustment and turn-taking dynamics, which can be reduced when interaction becomes “locked” in one direction. Our results are consistent with this conceptual distinction: Max_block_s quantifies the longest sustained period during which directional asymmetry is both significant and stable in sign, indexing the degree to which dyadic rhythmic interaction avoids prolonged unidirectional lock-in. Importantly, Max_block_s is not a direct measure of “communication quality” in a psychological sense; rather, it is a behavioral-structure proxy that may reflect reduced opportunities for bidirectional exchange at the rhythmic timescale. In this framing, shorter sustained unidirectional episodes may indicate more frequent re-entry into a state where mutual adaptation is possible, aligning with theories that synchronized rhythmic engagement can support affiliation and social bonding 16 , 17 . Such a perspective also resonates with work showing that synchrony can increase affiliation and cooperation 11 – 13 and can do so early in development 14 , while meta-analytic evidence underscores that effects are heterogeneous and context-dependent 15 . Our finding suggests that part of this heterogeneity may arise from micro-dynamics of interaction: even within the same group activity, children may differ in whether they remain in prolonged unidirectional influence patterns or engage in more dynamically shifting influence relationships. Facilitated drum circles are designed to balance structure and spontaneity: facilitators often guide participants through call-and-response, freeze games, and open improvisation, which can naturally induce changing roles. Leadership-related movement signatures have been identified in joint music performance (e.g., body sway reflecting leadership) 28 , implying that directional aspects of coordination can be expressed in bodily dynamics. In our setting, a long Max_block_s could reflect extended facilitator-driven guidance for a child who is not fully entrained, sustained child-driven deviation that others adapt to, or other stable asymmetries. Notably, our metric treats prolonged unidirectionality in either direction as the relevant structural feature, consistent with the interpretation that “stuckness” in a single directional mode—whether facilitator-led or child-led—may be associated with reduced OT responsiveness. From an endocrine perspective, OT is best understood as context-sensitive rather than uniformly “prosocial” 8,9 . The social salience hypothesis emphasizes that OT modulates attention and responsivity to socially relevant cues, with outcomes depending on context and individual differences 9 . In a drum circle, a child experiencing more fluid reciprocal rhythmic exchange may receive richer socially contingent cues (e.g., timing-sensitive feedback, shared prediction success, mutual responsiveness), potentially amplifying endocrine responses linked to social engagement. Conversely, prolonged unidirectional lock-in might reflect reduced contingency, lower perceived social reciprocity, or challenges in aligning with the group’s rhythmic structure—all plausible pathways to smaller OT changes. A methodological contribution of this work is the explicit separation of movement into a slow rhythm-band component and a beat-related component emphasizing event-like movement changes. The rhythm band plausibly captures slower oscillatory coordination of body movement that can reflect entrainment, shared pulse, and ongoing mutual adjustment. The beat-related component, derived from jerk and higher-frequency filtering, emphasizes transient events likely tied to striking actions and more punctate timing corrections. The TE heatmaps suggested that these layers exhibit qualitatively different interaction signatures, and exploratory endocrine associations also differed by layer: OT-related effects were most evident in the rhythm-band temporal structure (Max_block_s), whereas CORT-related trends appeared more aligned with beat-related variability (SD_dTE) and cross-layer difference indices. One interpretation is that rhythm-band dynamics more directly reflect relational attunement and perceived social engagement, which may be more closely linked to OT variability, whereas beat-related dynamics may capture arousal- or effort-related aspects of performance and attention, potentially more relevant to CORT. This interpretation is consistent with broader accounts that distinguish social-bonding processes linked to synchronized rhythmic engagement 16 , 17 from stress/arousal dynamics indexed by cortisol 10 . However, given the pilot nature of our dataset, this layer-based interpretation should be considered a working hypothesis for replication rather than a firm conclusion. Our endocrine outcomes were based on saliva, a noninvasive and pediatric-friendly sampling method. At the same time, salivary OT measurement is methodologically challenging due to low concentrations, assay variability, and lack of standardization across laboratories 29 , 30 . In addition, immunoassay-based OT estimates may be influenced by OT existing in multiple molecular forms (including protein-bound complexes), which can contribute to variability in absolute concentrations across studies and assays 31 . While repeated-measures within-subject designs can mitigate some sources of between-person variability, interpreting absolute OT levels (and even change scores) requires caution; nevertheless, salivary OT measurements can capture physiologically meaningful within-subject changes, including rapid increases reported in maternal contexts following infant stimulation 32 . Finally, because peripheral OT does not necessarily map directly onto central OT, transport mechanisms such as RAGE-mediated OT passage into the brain further highlight the complexity of interpreting peripheral measures 33 . We therefore emphasize effect sizes and patterns of association rather than strong mechanistic claims. Future work could strengthen inference by incorporating additional endocrine time points (e.g., post + recovery), validating assay procedures with standardized approaches, and triangulating endocrine outcomes with behavioral coding or self-report measures of social experience. This study has several important limitations. First, the sample size was small (n = 11) and the design was based on a single session, limiting statistical power and precision; confidence intervals for some exploratory associations were wide. Second, analyses involved multiple candidate interaction metrics across layers, raising the risk of false positives; we therefore frame results as exploratory and highlight the strongest, most interpretable association (Max_block_s × OT change) while reporting sensitivity analysis for an influential point. Third, saliva sampling was limited to pre and immediate post time points, which may not fully capture OT or CORT dynamics across the session and recovery period. Fourth, while TE provides a model-free estimate of directional predictive influence, TE estimation requires analytic choices (e.g., binning, history length, delay selection, window size) that can affect results; we attempted to mitigate spurious effects via surrogate-based significance testing and report parameters transparently (Methods; Supplementary Methods). Fifth, accelerometry captures movement but not the subjective or social-cognitive experience of interaction; integrating behavioral observation, facilitator notes, or participant-reported engagement would help interpret what prolonged unidirectional episodes represent psychologically. Replication with larger samples and multiple sessions is needed to establish robustness and generalizability. Future studies should (i) incorporate additional physiological signals (e.g., heart rate, heart-rate variability, electrodermal activity), (ii) add behavioral measures of engagement and perceived reciprocity, and (iii) evaluate whether Max_block_s generalizes across facilitators, group compositions, and settings. In summary, this exploratory pilot study suggests that children’s endocrine responses during a facilitated drum circle may relate less to the overall amount of directional influence and more to the temporal persistence of sustained unidirectional rhythmic influence. If replicated, these findings would support a view of rhythmic social interaction in which dynamic reciprocity-like structure—operationalized here as avoidance of prolonged unidirectional lock-in—may be a meaningful behavioral correlate of oxytocin variability during group music-making. Methods Study design and setting A school-based facilitated drum circle session was conducted on 1 December 2025 in a group setting. The schedule was: (i) 10:30–10:50 for preparation, questionnaires, and baseline saliva sampling; (ii) 10:50–11:20 for the drum circle; and (iii) 11:20–11:40 for device removal, questionnaires, and post-session saliva sampling (Fig. 1 ). The study used a pre–post design with repeated measures of salivary OT and CORT and continuous accelerometry during the drum circle. This study was conducted as a school-based exploratory pre–post study under naturalistic conditions, rather than as a randomized or controlled clinical efficacy trial. Participants Children were recruited through the participating school. Eleven children (age: 9–10 years, 5 boys and 6 girls) provided complete pre–post saliva samples and analyzable accelerometry data and were included in the present analyses (Table 1 ). This study was approved as a noninvasive medical study by the Kanazawa University Graduate School of Medical Sciences in 2022 (approval number 114191). It was conducted in accordance with the Ethical Guidelines for Clinical Studies of the Ministry of Health, Labour and Welfare of Japan and the tenets of the Declaration of Helsinki. Written informed consent was obtained from parents/guardians and assent from children prior to participation. Facilitated drum circle procedure The session consisted of drumming-only activities (no singing or background music). Drums were arranged in a circle and children selected a drum and seated themselves. The same trained facilitator led the session and an assistant supported logistics. Example activities included Call and Response, Drum Circle Freeze, and Drum Jam, consistent with commonly used facilitated drum circle structures and with our prior published protocol 22 . The facilitator moved between positions in the circle and occasionally to the center to guide group activities. Saliva collection To reduce acute confounds, children were instructed to avoid eating, drinking (except water), tooth brushing, and vigorous physical activity for at least 1 h prior to participation, consistent with standard saliva endocrine protocols and our prior work 22 . Saliva was collected immediately before the session and immediately after the session using sterile polypropylene tubes. Samples were placed on ice immediately after collection and stored frozen until assay. Salivary oxytocin and cortisol measurement Saliva samples were thawed and centrifuged (4°C, 1,500 × g, 10 min) and aliquoted into microtubes before storage at − 80°C until assay. Salivary OT was measured using a commercially available OT-ELISA kit (Enzo Life Sciences), and salivary CORT was measured using a commercial enzyme immunoassay kit (Salimetrics), following manufacturer instructions and procedures consistent with our previous published study 22 . Measurements were performed in duplicate, concentrations were obtained from standard curves, and assays were conducted by personnel blinded to participant identifiers in the analysis dataset where feasible. Accelerometry acquisition Accelerometry was recorded using a chest-mounted accelerometer and activity-monitoring application (E8G-ES2-0300; Hitachi, Ltd.) attached to the anterior chest of a dedicated vest worn by each participant. Tri-axial accelerometry was recorded at 20 Hz throughout the drum circle. Raw accelerometry data were exported for offline analysis. Accelerometry preprocessing and feature construction Orientation-robust magnitude. To reduce dependence on sensor orientation, we computed the vector magnitude: a(t) = sqrt(ax(t)^2 + ay(t)^2 + az(t)^2) Rhythm-band feature (0.3–3 Hz). To capture slower rhythmic coordination (e.g., body sway movement entrainment), 𝑎(𝑡) was band-pass filtered between 0.3 and 3 Hz using zero-phase filtering to obtain the rhythm-band series. Beat-related feature (event-like movement changes). To emphasize rapid, event-like changes plausibly related to striking behavior, we computed jerk as the discrete time derivative of 𝑎(𝑡) (scaled by sampling frequency), band-pass filtered jerk between 2 and 8 Hz, rectified it (absolute value), and computed a short moving RMS envelope (0.25 s). This yielded a continuous beat-related time series suitable for TE estimation. Windowed transfer entropy and directional asymmetry Transfer entropy estimation. For each facilitator–child dyad and each feature (rhythm and beat-related), we discretized the aligned continuous series into 𝐵 = 8 equiprobable bins (quantile binning) and computed discrete TE in both directions (TE(Fac→i), TE(i→Fac)) using log base 2 (bits) with one-step histories (k = l = 1) 23,24 . Windowing and delay selection. TE was computed in 60-s sliding windows advanced in 5-s steps. To accommodate sensorimotor delays, we evaluated candidate source-to-target delays and, within each window, selected the delay that maximized ∣ΔTE( t )∣, where: ΔTE(t) = TE(Fac→i, t) - TE(i→Fac, t) Candidate delays were 0.1–0.5 s (rhythm) and 0.05–0.25 s (beat-related). Surrogate-based significance testing To test whether observed Δ TE ( t ) exceeded chance levels given autocorrelation, we used a two-sided surrogate test per window based on circular time shifts of the driver series. For each window, 200 surrogates were generated by circularly shifting the driver by a random offset (minimum shift 3 s). For each surrogate, Δ TE was recomputed to form an empirical null distribution. A window was labeled significant if observed Δ TE ( t ) fell below the 2.5th percentile or above the 97.5th percentile of the surrogate distribution (α = 0.05, two-sided). Significant windows are indicated by circles in Fig. 3 . Derivation of individual-level interaction metrics We computed previously used TE summary indices (e.g., proportions of significant positive/negative asymmetry, reciprocity-like indices, and variability of Δ TE ; Table 2 ; Supplementary Methods). The primary temporal-structure metric was: Max_block_s (maximum sustained episode duration). For each window, we defined a ternary series s(t) ∈ {−1, 0, + 1}, where s(t) = + 1 if ΔTE(t) was significantly > 0, s(t) = − 1 if ΔTE(t) was significantly < 0, and s(t) = 0 otherwise. A unidirectional episode was defined as a maximal run of consecutive windows with constant non-zero sign; non-significant windows (s(t) = 0) terminated episodes. Episode duration was computed as W + (L − 1)×S, where W is the window length (60 s), S is the step size (5 s), and L is the run length (number of consecutive windows). Max_block_s was the maximum episode duration within the session, computed separately for the rhythm and beat components. Statistical analysis Hormone concentrations were log-transformed prior to change-score computation. Pre–post hormone changes were summarized as: Δlog10(OT) = log10(OTpost) − log10(OTpre) Δlog10(CORT) = log10(CORTpost) − log10(CORTpre) Group-level pre–post change was tested using paired t-tests (two-sided). Associations between TE-derived metrics and endocrine change were assessed using Spearman rank correlation (two-sided). Given the pilot design and multiple candidate metrics, analyses were interpreted as exploratory, with emphasis on effect sizes, precision, and sensitivity analysis. For the exploratory association between the rhythm-minus-beat difference in P_sig_pos and ΔCORT_log, uncertainty was additionally assessed using a nonparametric bootstrap procedure (10,000 resamples; Supplementary Methods). Large language model assistance A large language model was used to assist with English language editing. All outputs were reviewed and validated by the authors. Declarations Acknowledgements The authors thank Ms. Kazuko Iida for serving as the facilitator for the drum circle. Consent for publication Not applicable. Data Availability The datasets generated and/or analysed during the current study are not publicly available due to ethical restrictions related to research involving children. De-identified data and analysis code are available from the corresponding author upon reasonable request and with appropriate institutional approvals. Author contributions M.K. and Y.Y. conceived and designed the study, recruited participants, and developed the protocol. S.T., Y.O., K.F., H.H., and C.T. contributed to behavioral measurements, literature review, and data processing. M.K. and C.T. performed the statistical analyses. M.K. drafted the manuscript. All authors reviewed, revised, and approved the final manuscript. Funding This work was supported by the Moonshot Research and Development Program (grant number JPMJMS229C-14a) and JSPS KAKENHI (grant number 23K27526). Additional Information Competing interests. The authors declare no competing interests. References Fancourt, D. & Finn, S. in What is the evidence on the role of the arts in improving health and well-being? A scoping review WHO Health Evidence Network Synthesis Reports (2019). Williams, E. et al. 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Social vocalizations can release oxytocin in humans. Proc Biol Sci 277 , 2661–2666, doi:10.1098/rspb.2010.0567 (2010). Schladt, T. M. et al. Choir versus Solo Singing: Effects on Mood, and Salivary Oxytocin and Cortisol Concentrations. Front Hum Neurosci 11 , 430, doi:10.3389/fnhum.2017.00430 (2017). Papasteri, C. C. et al. Social Feedback During Sensorimotor Synchronization Changes Salivary Oxytocin and Behavioral States. Front Psychol 11 , 531046, doi:10.3389/fpsyg.2020.531046 (2020). Yuhi, T. et al. Salivary Oxytocin Concentration Changes during a Group Drumming Intervention for Maltreated School Children. Brain Sci 7 , doi:10.3390/brainsci7110152 (2017). Kikuchi, M., Tanaka, S., Furuhara, K., Higashida, H. & Tsuji, C. Differences in Oxytocin Response Between a Group of Friends and a Group of Strangers Following Facilitated Drum Circle Activities. Brain Behav 16 , e71183, doi:10.1002/brb3.71183 (2026). Schreiber, T. Measuring information transfer. Phys Rev Lett 85 , 461–464, doi:10.1103/PhysRevLett.85.461 (2000). Vicente, R., Wibral, M., Lindner, M. & Pipa, G. Transfer entropy--a model-free measure of effective connectivity for the neurosciences. J Comput Neurosci 30 , 45–67, doi:10.1007/s10827-010-0262-3 (2011). Trendafilov, D., Schmitz, G., Hwang, T. H., Effenberg, A. O. & Polani, D. Tilting Together: An Information-Theoretic Characterization of Behavioral Roles in Rhythmic Dyadic Interaction. Front Hum Neurosci 14 , 185, doi:10.3389/fnhum.2020.00185 (2020). Takamizawa, K. & Kawasaki, M. Transfer entropy for synchronized behavior estimation of interpersonal relationships in human communication: identifying leaders or followers. Sci Rep 9 , 10960, doi:10.1038/s41598-019-47525-6 (2019). Dotov, D., Delasanta, L., Cameron, D. J., Large, E. W. & Trainor, L. Collective dynamics support group drumming, reduce variability, and stabilize tempo drift. Elife 11 , doi:10.7554/eLife.74816 (2022). Chang, A., Livingstone, S. R., Bosnyak, D. J. & Trainor, L. J. Body sway reflects leadership in joint music performance. Proc Natl Acad Sci U S A 114 , E4134–E4141, doi:10.1073/pnas.1617657114 (2017). Tabak, B. A. et al. Advances in human oxytocin measurement: challenges and proposed solutions. Mol Psychiatry 28 , 127–140, doi:10.1038/s41380-022-01719-z (2023). Lopez-Arjona, M., Botia, M., Martinez-Subiela, S. & Ceron, J. J. Oxytocin measurements in saliva: an analytical perspective. BMC Vet Res 19 , 96, doi:10.1186/s12917-023-03661-w (2023). Yamamoto, Y. et al. Complement component C4a binds to oxytocin and modulates plasma oxytocin concentrations and social behavior in male mice. Biochem Biophys Res Commun 771 , 152004, doi:10.1016/j.bbrc.2025.152004 (2025). Minami, K. et al. Infant Stimulation Induced a Rapid Increase in Maternal Salivary Oxytocin. Brain Sci 12 , doi:10.3390/brainsci12091246 (2022). Yamamoto, Y. & Higashida, H. RAGE regulates oxytocin transport into the brain. Commun Biol 3 , 70, doi:10.1038/s42003-020-0799-2 (2020). Additional Declarations No competing interests reported. Supplementary Files SupplementaryMethods.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 29 Apr, 2026 Reviewers invited by journal 27 Apr, 2026 Editor assigned by journal 27 Apr, 2026 Editor invited by journal 09 Apr, 2026 Submission checks completed at journal 07 Apr, 2026 First submitted to journal 07 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9139008","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":632088538,"identity":"18dce2b3-77d8-4a2e-b859-db9cf55220b2","order_by":0,"name":"Mitsuru Kikuchi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABJElEQVRIie3Qv0oDMRzA8Z8E6pJya46T+gRCjkAoVHyWCwftUrTQwcHBm+widBUq+gqKq0OOwN1y0E0iN0mhU4eDQhEUMVIHtSnqJpLvkATCh/wBcLn+Ymg5Uc8MBOSXXWolS0P95Mfk/RhKpY3Y2hl4al6/VYzdqVRDsbfvDdWUPIICbyCh31slXKFagKeK87IdN0HHfSIz7p8aQooI2JmdICzVLi+7nECFRJImXNdfFIAGYNhK0PyNsNHBwpBjcak2F/fP5pTt9QQCQzgNujUCWomrDPMSG0LXE+6fyw4jZZs1oyIX1wU+fNqCDg4LkVjfMk4n1Uy2wuEoftBVdiQuxvlNOINWo5GrjFl+7HPRh7W50sYJ+06shCa/Ji6Xy/UPewXAPGcl2Uw4zAAAAABJRU5ErkJggg==","orcid":"","institution":"Kanazawa University","correspondingAuthor":true,"prefix":"","firstName":"Mitsuru","middleName":"","lastName":"Kikuchi","suffix":""},{"id":632088539,"identity":"2079e582-2c9c-410c-aa09-8f81623626cd","order_by":1,"name":"Yuko Yoshimura","email":"","orcid":"","institution":"Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Yuko","middleName":"","lastName":"Yoshimura","suffix":""},{"id":632088540,"identity":"509dd8fd-e05c-44cb-9f5c-f09f332f3911","order_by":2,"name":"Sanae Tanaka","email":"","orcid":"","institution":"Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Sanae","middleName":"","lastName":"Tanaka","suffix":""},{"id":632088541,"identity":"0db5b40f-8a83-445c-837a-151529466de9","order_by":3,"name":"Yuri Okanemasa","email":"","orcid":"","institution":"Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Yuri","middleName":"","lastName":"Okanemasa","suffix":""},{"id":632088542,"identity":"33c5a5c3-ff4a-482d-bfe5-bbb1dcb0ea2b","order_by":4,"name":"Kazumi Furuhara","email":"","orcid":"","institution":"Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Kazumi","middleName":"","lastName":"Furuhara","suffix":""},{"id":632088543,"identity":"074171a3-7af4-4ce1-a50e-d26b134e2a48","order_by":5,"name":"Haruhiro Higashida","email":"","orcid":"","institution":"Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Haruhiro","middleName":"","lastName":"Higashida","suffix":""},{"id":632088544,"identity":"e9804c29-c298-489a-a994-0205ef01fc6d","order_by":6,"name":"Chiharu Tsuji","email":"","orcid":"","institution":"Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Chiharu","middleName":"","lastName":"Tsuji","suffix":""}],"badges":[],"createdAt":"2026-03-16 14:23:30","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9139008/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9139008/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108631266,"identity":"5459b870-8e77-4d32-97e9-13b73d4a7d62","added_by":"auto","created_at":"2026-05-06 16:41:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":5040306,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStudy design and timeline.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSchematic of the school-based facilitated drum circle protocol conducted on 1 December 2025. Children completed setup and baseline saliva sampling (10:30–10:50), participated in a 30-min drum circle (10:50–11:20), and then completed device removal and post-session saliva sampling (11:20–11:40). Accelerometry was recorded continuously during the drum circle. Oxytocin and cortisol were measured from saliva pre and post.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-9139008/v1/56b911ef9cf1e840aabf4198.png"},{"id":108631269,"identity":"c92792cc-050b-4f4c-bdaa-b39f3f7b16c7","added_by":"auto","created_at":"2026-05-06 16:41:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":940676,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePre–post endocrine responses to drum circle participation.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(a) Log-transformed salivary oxytocin (OT) concentrations before and after the drum circle. (b) Log-transformed salivary cortisol (CORT) concentrations before and after the drum circle. Thin lines connect within-child paired samples; thick lines indicate group mean ± SEM.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-9139008/v1/e992602a3181a9418a3557e6.png"},{"id":108805184,"identity":"dce1064a-c8a0-4973-975a-fd68bdd1302d","added_by":"auto","created_at":"2026-05-08 15:25:07","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":16427215,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTime-resolved directional interaction dynamics in rhythm and beat movement components.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(a) Rhythm-band (0.3–3 Hz) directional asymmetry heatmap for facilitator–child dyads, computed as ΔTE(t) = TE(Fac→i) − TE(i→Fac) in 60-s windows advanced by 5 s. (b) Beat-related component (jerk-derived; 2–8 Hz band-pass with 0.25-s RMS envelope) ΔTE(t) heatmap using the same windowing scheme. Circles indicate windows significant relative to a two-sided circular-shift surrogate test (200 surrogates, α = 0.05). Positive values indicate net facilitator-to-child influence; negative values indicate net child-to-facilitator influence.\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-9139008/v1/0037bb0fa277f3281964bdfa.png"},{"id":108631267,"identity":"a398f75a-d1a9-4c22-85ab-adaab0ff6d8d","added_by":"auto","created_at":"2026-05-06 16:41:34","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":990166,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTemporal persistence of unidirectional rhythmic coupling is associated with oxytocin change.\u003cbr\u003e\n \u003c/strong\u003eScatter plot showing the association between the maximum sustained significant unidirectional episode duration (Max_block_s, rhythm band) and log10-transformed oxytocin change (ΔOT) across children (n = 11). Spearman’s rank correlation is shown in the panel. Points are labeled anonymously (No.1–No.11). The regression line is shown for visualization only.\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-9139008/v1/e9a0efe36d38b5ad36efd64f.png"},{"id":108809655,"identity":"6afb611e-856c-4c69-bb6d-e0cd6cd251ab","added_by":"auto","created_at":"2026-05-08 15:54:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":23487323,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9139008/v1/98839261-98a1-4fc7-8167-876fbb998beb.pdf"},{"id":108631271,"identity":"bc25c3cb-9a91-4aae-8510-17437c0a4735","added_by":"auto","created_at":"2026-05-06 16:41:35","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":19783,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMethods.docx","url":"https://assets-eu.researchsquare.com/files/rs-9139008/v1/0a8faacdcc68178fb7000f80.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Temporal persistence of unidirectional rhythmic coupling is inversely associated with salivary oxytocin change during facilitated drum circles in children","fulltext":[{"header":"Introduction","content":"\u003cp\u003eParticipatory arts-based activities are increasingly recognized as scalable approaches to support children\u0026rsquo;s mental health and social connectedness \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Facilitated drum circles are a prominent example because they combine accessible music-making with inherently interactive, reciprocity-like rhythmic exchange\u0026mdash;shared timing, imitation, and turn-taking\u0026mdash;within a group setting \u003csup\u003e\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Evaluations of drumming-based programs suggest potential benefits for social and emotional functioning in young people \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e, while work in adult or clinical populations indicates that group drumming can modulate biological markers relevant to stress- and health-related processes \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. However, the specific within-session interaction dynamics that may relate to children\u0026rsquo;s neuroendocrine responses, including salivary oxytocin, remain insufficiently characterized.\u003c/p\u003e \u003cp\u003eA plausible candidate mechanism linking rhythmic social activity to socioemotional outcomes is the oxytocin system. Oxytocin (OT) is a neuropeptide implicated in social approach, affiliative behavior, and context-dependent modulation of socioemotional processes \u003csup\u003e\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Importantly, contemporary accounts emphasize that OT effects are not uniformly \u0026ldquo;prosocial,\u0026rdquo; but are shaped by situational demands and individual factors, including social context and perceived salience of cues \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. In parallel, the hypothalamic\u0026ndash;pituitary\u0026ndash;adrenal (HPA) axis, indexed peripherally by cortisol (CORT), is responsive to stress, arousal, and social-evaluative processes; salivary CORT is commonly used as a noninvasive marker in psychoneuroendocrine research \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. Studying OT and CORT together may therefore help distinguish endocrine signatures related to social engagement versus arousal/stress-related activation during group activities.\u003c/p\u003e \u003cp\u003eA second line of evidence motivating the present work comes from research on interpersonal synchrony. Coordinated timing between individuals\u0026mdash;via movement, vocalization, or joint action\u0026mdash;can increase affiliation and cooperation \u003csup\u003e\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e, including in early development \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Meta-analytic work supports small-to-moderate prosocial effects of synchrony across tasks, with substantial heterogeneity \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. In the context of music and rhythm, theories propose that synchronized activities may promote social bonding via mechanisms such as \u0026ldquo;self\u0026ndash;other merging,\u0026rdquo; shared prediction, and neurochemical modulation, including endorphin-related pathways \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Consistent with endocrine involvement, salivary OT has been reported to show context-sensitive changes during socially engaging vocal or musical activities (e.g., social vocalizations), and singing-related effects may differ by performance format (e.g., choir versus solo singing), sometimes alongside changes in CORT and mood \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e.Experimental work further suggests that OT responses during sensorimotor synchronization can depend on social feedback and participant factors \u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e, underscoring the importance of interaction context; related intervention work in vulnerable child populations also supports the sensitivity of salivary OT to socially structured rhythmic activity \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eRecently, we reported that facilitated drum circle participation can be accompanied by changes in salivary OT in children, and that pre-existing social relationships may modulate this response, with increases being more evident when the activity is shared with friends than with strangers \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. That study was conducted in a laboratory setting and focused on group-level endocrine changes and between-group differences. However, a key unresolved question is why endocrine responses vary substantially between children even within a shared session. Most prior work on synchrony and group music has relied on undirected coupling measures (e.g., correlation, phase-locking), which quantify similarity or coordination strength but do not directly capture who influences whom over time. In interactive rhythmic settings, communication-like processes may depend not only on coordination strength but also on the directionality and temporal organization of influence\u0026mdash;whether interactions become prolonged in one directional mode or remain mutually adaptive.\u003c/p\u003e \u003cp\u003eTo quantify directional interaction structure, information-theoretic approaches such as transfer entropy (TE) provide a model-free estimate of directed predictive influence between time series \u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. TE has been applied to characterize behavioral roles and leader\u0026ndash;follower dynamics in rhythmic dyadic interaction \u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, and to describe directed coordination in group drumming contexts \u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. In musical joint action, leadership can also manifest in movement dynamics such as body sway, suggesting that directional aspects of coordination may be behaviorally meaningful beyond overt turn-taking \u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e. Building on these ideas, we examined TE-based directional dynamics between a facilitator and each child during a school-based drum circle, while explicitly separating movement into frequency layers: a slow rhythm band (capturing ongoing rhythmic coordination) and a beat-related component emphasizing event-like movements (such as striking or transient timing adjustments). We further introduced a temporal-structure metric, Max_block_s, indexing the longest sustained significant unidirectional TE episode, as a candidate marker of reduced reciprocal adaptation.\u003c/p\u003e \u003cp\u003eIn this exploratory pilot study, our primary aim was to test whether directional interaction structure, particularly the \u003cem\u003etemporal persistence\u003c/em\u003e of unidirectional rhythmic influence, covaries with individual differences in salivary OT change during drum circle participation. Secondarily, we explored whether beat-related interaction variability might relate to CORT change, consistent with the possibility that different frequency layers reflect partially distinct psychophysiological processes. Given the small sample size and single-session design, analyses were framed as exploratory and effect-size\u0026ndash;oriented rather than confirmatory.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eParticipant and data overview\u003c/h2\u003e\n \u003cp\u003eEleven children provided usable pre\u0026ndash;post saliva samples and analyzable accelerometry recordings during a school-based facilitated drum circle session (Fig. \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Hormone concentrations were log-transformed before computing pre\u0026ndash;post change indices due to typical right-skew in salivary endocrine measures (see Methods). Summary descriptive statistics for OT and CORT (pre and post) are reported in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePre\u0026ndash;post salivary endocrine concentrations (log10-transformed) during drum circle participation in children (n\u0026thinsp;=\u0026thinsp;11).\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eMeasure\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c2\"\u003e\n \u003cp\u003ePre\u003c/p\u003e\n \u003cp\u003emean (SD)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c3\"\u003e\n \u003cp\u003ePost\u003c/p\u003e\n \u003cp\u003emean (SD)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003cp\u003e(df\u0026thinsp;=\u0026thinsp;10)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c5\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003cp\u003e(two-sided)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eOxytocin (log10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e2.040 (0.370)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e2.246 (0.260)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e2.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e0.022\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cp\u003eCortisol (log10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\n \u003cp\u003e\u0026minus;0.906 (0.134)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\n \u003cp\u003e\u0026minus;0.828 (0.281)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\n \u003cp\u003e1.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\n \u003cp\u003e0.275\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003ch3\u003eGroup-level endocrine changes (Fig. 2)\u003c/h3\u003e\n\u003cp\u003eSalivary OT increased at the group level from pre- to post-session (paired t-test, t(10)\u0026thinsp;=\u0026thinsp;2.71, p\u0026thinsp;=\u0026thinsp;0.022; Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), consistent with prior work showing that facilitated drum circles can elicit salivary OT increases in children under specific social conditions, particularly when the activity is shared with friends \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. In contrast, salivary CORT did not show a significant pre\u0026ndash;post change at the group level (paired t-test, two-sided, t(10)\u0026thinsp;=\u0026thinsp;1.15, p\u0026thinsp;=\u0026thinsp;0.275) and exhibited only a small upward trend.\u003c/p\u003e\n\u003ch3\u003eDirectional interaction dynamics differ between rhythm- and beat-related movement components\u003c/h3\u003e\n\u003cp\u003eTo characterize how facilitator\u0026ndash;child interaction unfolded over time, we computed windowed TE in two movement components derived from tri-axial accelerometry: a rhythm band (0.3\u0026ndash;3 Hz) capturing slower rhythmic body coordination and a beat-related component derived from jerk-based event-like movement changes (Methods). For each dyad, we quantified directional asymmetry as \u0026Delta;TE(t)\u0026thinsp;=\u0026thinsp;TE(Fac\u0026rarr;i)\u0026thinsp;\u0026minus;\u0026thinsp;TE(i\u0026rarr;Fac) and visualized its temporal evolution using heatmaps (Fig. \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea\u0026ndash;b), where circles indicate windows significant relative to a two-sided circular-shift surrogate test (200 surrogates, \u0026alpha;\u0026thinsp;=\u0026thinsp;0.05). Across children, rhythm-band \u0026Delta;TE(t) showed pronounced time-varying structure with intermittent significant episodes and participant-specific patterns, consistent with dynamic adjustment processes at the rhythmic level. In contrast, the beat-related component showed a distinct interaction signature, consistent with more event-structured coordination. These frequency-layer\u0026ndash;dependent patterns motivated subsequent individual-differences analyses linking interaction structure to endocrine changes.\u003c/p\u003e\n\u003ch3\u003eRhythm-band interaction structure is associated with oxytocin change\u003c/h3\u003e\n\u003cp\u003eWe next examined whether individual differences in OT change were related to TE-derived features in the rhythm band (Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Several previously used directional indices showed moderate, non-significant associations with OT change in this pilot sample (e.g., P_sig_pos: \u0026rho; = \u0026minus;0.523, p\u0026thinsp;=\u0026thinsp;0.099; SD_dTE: \u0026rho; = \u0026minus;0.473, p\u0026thinsp;=\u0026thinsp;0.142; n\u0026thinsp;=\u0026thinsp;11).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003cstrong\u003eTable 2. Individual-level TE-derived directional interaction metrics and their associations with endocrine change in children (n = 11).\u0026nbsp;\u003c/strong\u003eSpearman rank correlations are reported between selected TE metrics and log-transformed endocrine change (\u0026Delta;OT_log, \u0026Delta;CORT_log).\u0026nbsp;\u003c/div\u003e\n \u003cp\u003e\u003cstrong\u003ea. Rhythm-band interaction metrics\u003c/strong\u003e\u003c/p\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"574\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 27.0035%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMetric\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 17.4216%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026rho; (\u0026Delta;OT_log)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 13.2404%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026rho; (\u0026Delta;CORT_log)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.09756%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.8084%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 27.0035%;\"\u003e\n \u003cp\u003eP_sig_pos\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 17.4216%;\"\u003e\n \u003cp\u003e\u0026minus;0.523\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 13.2404%;\"\u003e\n \u003cp\u003e0.099\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003e\u0026minus;0.128\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.09756%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.8084%;\"\u003e\n \u003cp\u003e0.707\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 27.0035%;\"\u003e\n \u003cp\u003eP_sig_neg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 17.4216%;\"\u003e\n \u003cp\u003e\u0026minus;0.196\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 13.2404%;\"\u003e\n \u003cp\u003e0.564\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003e0.401\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.09756%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.8084%;\"\u003e\n \u003cp\u003e0.222\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 27.0035%;\"\u003e\n \u003cp\u003eReciprocity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 17.4216%;\"\u003e\n \u003cp\u003e0.318\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 13.2404%;\"\u003e\n \u003cp\u003e0.340\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003e0.155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.09756%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.8084%;\"\u003e\n \u003cp\u003e0.650\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 27.0035%;\"\u003e\n \u003cp\u003eSD_dTE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 17.4216%;\"\u003e\n \u003cp\u003e\u0026minus;0.473\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 13.2404%;\"\u003e\n \u003cp\u003e0.142\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003e0.382\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.09756%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.8084%;\"\u003e\n \u003cp\u003e0.247\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 27.0035%;\"\u003e\n \u003cp\u003eSwitch_rate_per_min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 17.4216%;\"\u003e\n \u003cp\u003e\u0026minus;0.229\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 13.2404%;\"\u003e\n \u003cp\u003e0.499\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003e\u0026minus;0.326\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.09756%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.8084%;\"\u003e\n \u003cp\u003e0.327\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 27.0035%;\"\u003e\n \u003cp\u003eMax_block_s\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 17.4216%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026minus;0.720\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 13.2404%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.013*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21.4286%;\"\u003e\n \u003cp\u003e\u0026minus;0.132\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6.09756%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.8084%;\"\u003e\n \u003cp\u003e0.699\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e*P \u0026lt; 0.05\u003c/p\u003e\n \u003cp\u003eSensitivity analysis excluding the participant with the largest Max_block_s value (ID No.5, 200 s): Max_block_s vs \u0026Delta;OT_log \u0026rarr; \u0026rho; = \u0026minus;0.626, p = 0.053 (n = 10).\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eb. Beat-related metrics\u003c/strong\u003e\u003c/p\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"539\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMetric\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026rho; (\u0026Delta;OT_log)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026rho; (\u0026Delta;CORT_log)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eP_sig_pos\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e\u0026minus;0.155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.650\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e0.391\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.235\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eP_sig_neg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e0.383\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.245\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e0.200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.555\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eReciprocity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e0.091\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.790\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e\u0026minus;0.345\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.298\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eSD_dTE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e\u0026minus;0.500\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.117\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e0.509\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.110\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eSwitch_rate_per_min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e0.314\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.347\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e0.333\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.318\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eMax_block_s\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e0.446\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.169\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e0.326\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.327\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003cstrong\u003ec. LayerDiff (Rhythm\u0026minus;Beat) metrics\u003c/strong\u003e\u003c/p\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"539\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMetric\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026rho; (\u0026Delta;OT_log)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026rho; (\u0026Delta;CORT_log)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eP_sig_pos\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e-0.232\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.492\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e-0.451\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.164\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eP_sig_neg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e-0.464\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.151\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e0.191\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.574\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eReciprocity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e-0.009\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.979\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e0.409\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.212\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eSD_dTE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e-0.264\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.433\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e0.273\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.417\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eSwitch_rate_per_min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e-0.269\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.424\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e-0.419\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.199\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 28.757%;\"\u003e\n \u003cp\u003eMax_block_s\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 18.5529%;\"\u003e\n \u003cp\u003e-0.729\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 14.1002%;\"\u003e\n \u003cp\u003e0.011*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 22.82%;\"\u003e\n \u003cp\u003e-0.087\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 15.7699%;\"\u003e\n \u003cp\u003e0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e*P \u0026lt; 0.05\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003cstrong\u003eNote\u003c/strong\u003e. TE-derived directional interaction metrics and associations with endocrine change. Individual-level summary metrics derived from windowed transfer entropy (TE) analyses were computed separately for rhythm-band (0.3\u0026ndash;3 Hz) and beat-related movement components. In panel c, cross-layer difference metrics were defined as the rhythm-band value minus the corresponding beat-related value for each metric. Metrics include the proportion of significant facilitator-to-child influence (P_sig_pos), proportion of significant child-to-facilitator influence (P_sig_neg), reciprocity-like indices, variability of directional asymmetry (SD_dTE), switching rate of significant directional states, and maximum sustained unidirectional episode duration (Max_block_s). Spearman correlations with log-transformed oxytocin (\u0026Delta;OT_log) and cortisol (\u0026Delta;CORT_log) changes are shown. A sensitivity analysis excluding the participant with the largest Max_block_s value is reported for transparency.\u003c/p\u003e\n\u003c/div\u003e\n\u003cp\u003eIn contrast, Max_block_s\u0026mdash;the maximum duration (seconds) of a sustained significant unidirectional \u0026Delta;TE episode in the rhythm band\u0026mdash;showed a strong negative association with OT change (Spearman \u0026rho; = \u0026minus;0.720, p\u0026thinsp;=\u0026thinsp;0.013; n\u0026thinsp;=\u0026thinsp;11; Fig. \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Thus, children exhibiting longer sustained unidirectional rhythmic influence (in either direction) tended to show smaller OT increases (or decreases) from pre to post.\u003c/p\u003e\n\u003ch3\u003eSensitivity analysis for an influential observation\u003c/h3\u003e\n\u003cp\u003eTo evaluate robustness to an influential observation, we examined the child with the largest Max_block_s value (ID: No.5; Max_block_s\u0026thinsp;=\u0026thinsp;200 s), who also showed a decrease in OT (\u0026Delta;OT_log\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.130). Excluding this child (n\u0026thinsp;=\u0026thinsp;10) yielded a similar-magnitude negative association with reduced precision (Spearman \u0026rho; = \u0026minus;0.626, p\u0026thinsp;=\u0026thinsp;0.053). These results suggest that the observed relationship is not solely driven by a single data point, while also highlighting the uncertainty inherent in small samples.\u003c/p\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eExploratory cross-layer analyses and associations with cortisol\u003c/h2\u003e\n \u003cp\u003eExploratory cross-layer analyses yielded two preliminary patterns (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). First, the rhythm-minus-beat difference in Max_block_s showed a strong negative association with \u0026Delta;OT_log (\u0026rho; = \u0026minus;0.729, p\u0026thinsp;=\u0026thinsp;0.011; n\u0026thinsp;=\u0026thinsp;11), indicating that larger rhythm\u0026ndash;beat separation in sustained unidirectional episode duration was associated with smaller OT increases. Second, beat-band SD_dTE showed a moderate positive association with \u0026Delta;CORT_log (\u0026rho;\u0026thinsp;=\u0026thinsp;0.509, p\u0026thinsp;=\u0026thinsp;0.110; n\u0026thinsp;=\u0026thinsp;11), which attenuated after excluding the influential observation (\u0026rho;\u0026thinsp;=\u0026thinsp;0.350). The rhythm-minus-beat difference in the positive-direction significance proportion (P_sig_pos) also showed a moderate negative association with \u0026Delta;CORT_log (\u0026rho; = \u0026minus;0.451, p\u0026thinsp;=\u0026thinsp;0.164), but bootstrap uncertainty for this association was substantial (95% CI: \u0026minus;0.617 to 0.611), indicating low precision in this pilot dataset (Supplementary Methods). These cross-layer results are exploratory and should be interpreted primarily as targets for replication.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this school-based exploratory study of children participating in a facilitated drum circle, we observed two main findings. First, salivary OT increased at the group level from pre to post participation, broadly consistent with prior work showing that facilitated drum circles can elicit salivary OT increases in children under specific social conditions, particularly when the activity is shared with friends 22. Second, and centrally, individual differences in OT change were most strongly associated not with the overall magnitude of directional influence, but with the temporal persistence of unidirectional rhythmic influence captured by Max_block_s. Children who exhibited longer sustained significant unidirectional influence episodes in the rhythm band tended to show smaller OT increases (or decreases). This pattern supports the broader idea that in interactive rhythmic contexts, endocrine variability may relate to how influence is organized over time, rather than to influence strength alone.\u003c/p\u003e \u003cp\u003eMost prior movement-synchrony studies emphasize coupling strength (e.g., correlation, phase synchrony), which captures similarity but not the directional organization of interaction. Yet interactive communication-like processes often involve ongoing mutual adjustment and turn-taking dynamics, which can be reduced when interaction becomes \u0026ldquo;locked\u0026rdquo; in one direction. Our results are consistent with this conceptual distinction: Max_block_s quantifies the longest sustained period during which directional asymmetry is both significant and stable in sign, indexing the degree to which dyadic rhythmic interaction avoids prolonged unidirectional lock-in. Importantly, Max_block_s is not a direct measure of \u0026ldquo;communication quality\u0026rdquo; in a psychological sense; rather, it is a behavioral-structure proxy that may reflect reduced opportunities for bidirectional exchange at the rhythmic timescale. In this framing, shorter sustained unidirectional episodes may indicate more frequent re-entry into a state where mutual adaptation is possible, aligning with theories that synchronized rhythmic engagement can support affiliation and social bonding \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Such a perspective also resonates with work showing that synchrony can increase affiliation and cooperation \u003csup\u003e\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e and can do so early in development \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, while meta-analytic evidence underscores that effects are heterogeneous and context-dependent \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Our finding suggests that part of this heterogeneity may arise from micro-dynamics of interaction: even within the same group activity, children may differ in whether they remain in prolonged unidirectional influence patterns or engage in more dynamically shifting influence relationships.\u003c/p\u003e \u003cp\u003e Facilitated drum circles are designed to balance structure and spontaneity: facilitators often guide participants through call-and-response, freeze games, and open improvisation, which can naturally induce changing roles. Leadership-related movement signatures have been identified in joint music performance (e.g., body sway reflecting leadership) \u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e, implying that directional aspects of coordination can be expressed in bodily dynamics. In our setting, a long Max_block_s could reflect extended facilitator-driven guidance for a child who is not fully entrained, sustained child-driven deviation that others adapt to, or other stable asymmetries. Notably, our metric treats prolonged unidirectionality in either direction as the relevant structural feature, consistent with the interpretation that \u0026ldquo;stuckness\u0026rdquo; in a single directional mode\u0026mdash;whether facilitator-led or child-led\u0026mdash;may be associated with reduced OT responsiveness.\u003c/p\u003e \u003cp\u003eFrom an endocrine perspective, OT is best understood as context-sensitive rather than uniformly \u0026ldquo;prosocial\u0026rdquo; \u003csup\u003e8,9\u003c/sup\u003e. The social salience hypothesis emphasizes that OT modulates attention and responsivity to socially relevant cues, with outcomes depending on context and individual differences \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. In a drum circle, a child experiencing more fluid reciprocal rhythmic exchange may receive richer socially contingent cues (e.g., timing-sensitive feedback, shared prediction success, mutual responsiveness), potentially amplifying endocrine responses linked to social engagement. Conversely, prolonged unidirectional lock-in might reflect reduced contingency, lower perceived social reciprocity, or challenges in aligning with the group\u0026rsquo;s rhythmic structure\u0026mdash;all plausible pathways to smaller OT changes.\u003c/p\u003e \u003cp\u003eA methodological contribution of this work is the explicit separation of movement into a slow rhythm-band component and a beat-related component emphasizing event-like movement changes. The rhythm band plausibly captures slower oscillatory coordination of body movement that can reflect entrainment, shared pulse, and ongoing mutual adjustment. The beat-related component, derived from jerk and higher-frequency filtering, emphasizes transient events likely tied to striking actions and more punctate timing corrections. The TE heatmaps suggested that these layers exhibit qualitatively different interaction signatures, and exploratory endocrine associations also differed by layer: OT-related effects were most evident in the rhythm-band temporal structure (Max_block_s), whereas CORT-related trends appeared more aligned with beat-related variability (SD_dTE) and cross-layer difference indices.\u003c/p\u003e \u003cp\u003eOne interpretation is that rhythm-band dynamics more directly reflect relational attunement and perceived social engagement, which may be more closely linked to OT variability, whereas beat-related dynamics may capture arousal- or effort-related aspects of performance and attention, potentially more relevant to CORT. This interpretation is consistent with broader accounts that distinguish social-bonding processes linked to synchronized rhythmic engagement \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e from stress/arousal dynamics indexed by cortisol \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. However, given the pilot nature of our dataset, this layer-based interpretation should be considered a working hypothesis for replication rather than a firm conclusion.\u003c/p\u003e \u003cp\u003eOur endocrine outcomes were based on saliva, a noninvasive and pediatric-friendly sampling method. At the same time, salivary OT measurement is methodologically challenging due to low concentrations, assay variability, and lack of standardization across laboratories \u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. In addition, immunoassay-based OT estimates may be influenced by OT existing in multiple molecular forms (including protein-bound complexes), which can contribute to variability in absolute concentrations across studies and assays \u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. While repeated-measures within-subject designs can mitigate some sources of between-person variability, interpreting absolute OT levels (and even change scores) requires caution; nevertheless, salivary OT measurements can capture physiologically meaningful within-subject changes, including rapid increases reported in maternal contexts following infant stimulation \u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e. Finally, because peripheral OT does not necessarily map directly onto central OT, transport mechanisms such as RAGE-mediated OT passage into the brain further highlight the complexity of interpreting peripheral measures \u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. We therefore emphasize effect sizes and patterns of association rather than strong mechanistic claims. Future work could strengthen inference by incorporating additional endocrine time points (e.g., post\u0026thinsp;+\u0026thinsp;recovery), validating assay procedures with standardized approaches, and triangulating endocrine outcomes with behavioral coding or self-report measures of social experience.\u003c/p\u003e \u003cp\u003eThis study has several important limitations. First, the sample size was small (n\u0026thinsp;=\u0026thinsp;11) and the design was based on a single session, limiting statistical power and precision; confidence intervals for some exploratory associations were wide. Second, analyses involved multiple candidate interaction metrics across layers, raising the risk of false positives; we therefore frame results as exploratory and highlight the strongest, most interpretable association (Max_block_s \u0026times; OT change) while reporting sensitivity analysis for an influential point. Third, saliva sampling was limited to pre and immediate post time points, which may not fully capture OT or CORT dynamics across the session and recovery period. Fourth, while TE provides a model-free estimate of directional predictive influence, TE estimation requires analytic choices (e.g., binning, history length, delay selection, window size) that can affect results; we attempted to mitigate spurious effects via surrogate-based significance testing and report parameters transparently (Methods; Supplementary Methods). Fifth, accelerometry captures movement but not the subjective or social-cognitive experience of interaction; integrating behavioral observation, facilitator notes, or participant-reported engagement would help interpret what prolonged unidirectional episodes represent psychologically.\u003c/p\u003e \u003cp\u003eReplication with larger samples and multiple sessions is needed to establish robustness and generalizability. Future studies should (i) incorporate additional physiological signals (e.g., heart rate, heart-rate variability, electrodermal activity), (ii) add behavioral measures of engagement and perceived reciprocity, and (iii) evaluate whether Max_block_s generalizes across facilitators, group compositions, and settings.\u003c/p\u003e \u003cp\u003eIn summary, this exploratory pilot study suggests that children\u0026rsquo;s endocrine responses during a facilitated drum circle may relate less to the overall amount of directional influence and more to the temporal persistence of sustained unidirectional rhythmic influence. If replicated, these findings would support a view of rhythmic social interaction in which dynamic reciprocity-like structure\u0026mdash;operationalized here as avoidance of prolonged unidirectional lock-in\u0026mdash;may be a meaningful behavioral correlate of oxytocin variability during group music-making.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and setting\u003c/h2\u003e \u003cp\u003eA school-based facilitated drum circle session was conducted on 1 December 2025 in a group setting. The schedule was: (i) 10:30\u0026ndash;10:50 for preparation, questionnaires, and baseline saliva sampling; (ii) 10:50\u0026ndash;11:20 for the drum circle; and (iii) 11:20\u0026ndash;11:40 for device removal, questionnaires, and post-session saliva sampling (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The study used a pre\u0026ndash;post design with repeated measures of salivary OT and CORT and continuous accelerometry during the drum circle. This study was conducted as a school-based exploratory pre\u0026ndash;post study under naturalistic conditions, rather than as a randomized or controlled clinical efficacy trial.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eChildren were recruited through the participating school. Eleven children (age: 9\u0026ndash;10 years, 5 boys and 6 girls) provided complete pre\u0026ndash;post saliva samples and analyzable accelerometry data and were included in the present analyses (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). This study was approved as a noninvasive medical study by the Kanazawa University Graduate School of Medical Sciences in 2022 (approval number 114191). It was conducted in accordance with the Ethical Guidelines for Clinical Studies of the Ministry of Health, Labour and Welfare of Japan and the tenets of the Declaration of Helsinki. Written informed consent was obtained from parents/guardians and assent from children prior to participation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eFacilitated drum circle procedure\u003c/h2\u003e \u003cp\u003eThe session consisted of drumming-only activities (no singing or background music). Drums were arranged in a circle and children selected a drum and seated themselves. The same trained facilitator led the session and an assistant supported logistics. Example activities included Call and Response, Drum Circle Freeze, and Drum Jam, consistent with commonly used facilitated drum circle structures and with our prior published protocol \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. The facilitator moved between positions in the circle and occasionally to the center to guide group activities.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eSaliva collection\u003c/h2\u003e \u003cp\u003eTo reduce acute confounds, children were instructed to avoid eating, drinking (except water), tooth brushing, and vigorous physical activity for at least 1 h prior to participation, consistent with standard saliva endocrine protocols and our prior work \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Saliva was collected immediately before the session and immediately after the session using sterile polypropylene tubes. Samples were placed on ice immediately after collection and stored frozen until assay.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eSalivary oxytocin and cortisol measurement\u003c/h2\u003e \u003cp\u003eSaliva samples were thawed and centrifuged (4\u0026deg;C, 1,500 \u0026times; g, 10 min) and aliquoted into microtubes before storage at \u0026minus;\u0026thinsp;80\u0026deg;C until assay. Salivary OT was measured using a commercially available OT-ELISA kit (Enzo Life Sciences), and salivary CORT was measured using a commercial enzyme immunoassay kit (Salimetrics), following manufacturer instructions and procedures consistent with our previous published study \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Measurements were performed in duplicate, concentrations were obtained from standard curves, and assays were conducted by personnel blinded to participant identifiers in the analysis dataset where feasible.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eAccelerometry acquisition\u003c/h2\u003e \u003cp\u003eAccelerometry was recorded using a chest-mounted accelerometer and activity-monitoring application (E8G-ES2-0300; Hitachi, Ltd.) attached to the anterior chest of a dedicated vest worn by each participant. Tri-axial accelerometry was recorded at 20 Hz throughout the drum circle. Raw accelerometry data were exported for offline analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eAccelerometry preprocessing and feature construction\u003c/h2\u003e \u003cp\u003eOrientation-robust magnitude. To reduce dependence on sensor orientation, we computed the vector magnitude:\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003ea(t) = sqrt(ax(t)^2\u0026thinsp;+\u0026thinsp;ay(t)^2\u0026thinsp;+\u0026thinsp;az(t)^2)\u003c/h2\u003e \u003cp\u003eRhythm-band feature (0.3\u0026ndash;3 Hz). To capture slower rhythmic coordination (e.g., body sway movement entrainment), \u0026#119886;(\u0026#119905;) was band-pass filtered between 0.3 and 3 Hz using zero-phase filtering to obtain the rhythm-band series.\u003c/p\u003e \u003cp\u003eBeat-related feature (event-like movement changes). To emphasize rapid, event-like changes plausibly related to striking behavior, we computed jerk as the discrete time derivative of \u0026#119886;(\u0026#119905;) (scaled by sampling frequency), band-pass filtered jerk between 2 and 8 Hz, rectified it (absolute value), and computed a short moving RMS envelope (0.25 s). This yielded a continuous beat-related time series suitable for TE estimation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eWindowed transfer entropy and directional asymmetry\u003c/h2\u003e \u003cp\u003eTransfer entropy estimation. For each facilitator\u0026ndash;child dyad and each feature (rhythm and beat-related), we discretized the aligned continuous series into \u0026#119861; = 8 equiprobable bins (quantile binning) and computed discrete TE in both directions (TE(Fac\u0026rarr;i), TE(i\u0026rarr;Fac)) using log base 2 (bits) with one-step histories (k\u0026thinsp;=\u0026thinsp;l = 1) \u003csup\u003e23,24\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eWindowing and delay selection. TE was computed in 60-s sliding windows advanced in 5-s steps. To accommodate sensorimotor delays, we evaluated candidate source-to-target delays and, within each window, selected the delay that maximized ∣ΔTE(\u003cem\u003et\u003c/em\u003e)∣, where:\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eΔTE(t)\u0026thinsp;=\u0026thinsp;TE(Fac\u0026rarr;i, t) - TE(i\u0026rarr;Fac, t)\u003c/h2\u003e \u003cp\u003eCandidate delays were 0.1\u0026ndash;0.5 s (rhythm) and 0.05\u0026ndash;0.25 s (beat-related).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eSurrogate-based significance testing\u003c/h2\u003e \u003cp\u003eTo test whether observed Δ\u003cem\u003eTE\u003c/em\u003e(\u003cem\u003et\u003c/em\u003e) exceeded chance levels given autocorrelation, we used a two-sided surrogate test per window based on circular time shifts of the driver series. For each window, 200 surrogates were generated by circularly shifting the driver by a random offset (minimum shift 3 s). For each surrogate, Δ\u003cem\u003eTE\u003c/em\u003e was recomputed to form an empirical null distribution. A window was labeled significant if observed Δ\u003cem\u003eTE\u003c/em\u003e(\u003cem\u003et\u003c/em\u003e) fell below the 2.5th percentile or above the 97.5th percentile of the surrogate distribution (α\u0026thinsp;=\u0026thinsp;0.05, two-sided). Significant windows are indicated by circles in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003eDerivation of individual-level interaction metrics\u003c/h2\u003e \u003cp\u003eWe computed previously used TE summary indices (e.g., proportions of significant positive/negative asymmetry, reciprocity-like indices, and variability of Δ\u003cem\u003eTE\u003c/em\u003e; Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Supplementary Methods). The primary temporal-structure metric was:\u003c/p\u003e \u003cp\u003e \u003cem\u003eMax_block_s (maximum sustained episode duration).\u003c/em\u003e \u003c/p\u003e \u003cp\u003eFor each window, we defined a ternary series s(t) \u0026isin; {\u0026minus;1, 0, +\u0026thinsp;1}, where s(t)\u0026thinsp;=\u0026thinsp;+\u0026thinsp;1 if ΔTE(t) was significantly\u0026thinsp;\u0026gt;\u0026thinsp;0, s(t)\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;1 if ΔTE(t) was significantly\u0026thinsp;\u0026lt;\u0026thinsp;0, and s(t)\u0026thinsp;=\u0026thinsp;0 otherwise. A unidirectional episode was defined as a maximal run of consecutive windows with constant non-zero sign; non-significant windows (s(t)\u0026thinsp;=\u0026thinsp;0) terminated episodes. Episode duration was computed as W + (L\u0026thinsp;\u0026minus;\u0026thinsp;1)\u0026times;S, where W is the window length (60 s), S is the step size (5 s), and L is the run length (number of consecutive windows). Max_block_s was the maximum episode duration within the session, computed separately for the rhythm and beat components.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eHormone concentrations were log-transformed prior to change-score computation. Pre\u0026ndash;post hormone changes were summarized as:\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003eΔlog10(OT) = log10(OTpost) \u0026minus; log10(OTpre)\u003c/h2\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003eΔlog10(CORT) = log10(CORTpost) \u0026minus; log10(CORTpre)\u003c/h2\u003e \u003cp\u003eGroup-level pre\u0026ndash;post change was tested using paired t-tests (two-sided). Associations between TE-derived metrics and endocrine change were assessed using Spearman rank correlation (two-sided). Given the pilot design and multiple candidate metrics, analyses were interpreted as exploratory, with emphasis on effect sizes, precision, and sensitivity analysis. For the exploratory association between the rhythm-minus-beat difference in P_sig_pos and ΔCORT_log, uncertainty was additionally assessed using a nonparametric bootstrap procedure (10,000 resamples; Supplementary Methods).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section3\"\u003e \u003ch2\u003eLarge language model assistance\u003c/h2\u003e \u003cp\u003eA large language model was used to assist with English language editing. All outputs were reviewed and validated by the authors.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;The authors thank Ms. Kazuko Iida for serving as the facilitator for the drum circle.\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003eData Availability\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analysed during the current study are not publicly available due to ethical restrictions related to research involving children. De-identified data and analysis code are available from the corresponding author upon reasonable request and with appropriate institutional approvals.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eM.K. and Y.Y. conceived and designed the study, recruited participants, and developed the protocol. S.T., Y.O., K.F., H.H., and C.T. contributed to behavioral measurements, literature review, and data processing. M.K. and C.T. performed the statistical analyses. M.K. drafted the manuscript. All authors reviewed, revised, and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;This work was supported by the Moonshot Research and Development Program (grant number JPMJMS229C-14a) and JSPS KAKENHI (grant number 23K27526).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional Information\u003cbr\u003e\u0026nbsp;Competing interests.\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eFancourt, D. \u0026amp; Finn, S. in \u003cem\u003eWhat is the evidence on the role of the arts in improving health and well-being? 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RAGE regulates oxytocin transport into the brain. \u003cem\u003eCommun Biol\u003c/em\u003e \u003cstrong\u003e3\u003c/strong\u003e, 70, doi:10.1038/s42003-020-0799-2 (2020).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Directional coupling, Drum circle, Interpersonal synchrony, Oxytocin, Rhythmic interaction, Transfer entropy","lastPublishedDoi":"10.21203/rs.3.rs-9139008/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9139008/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFacilitated drum circles may promote social bonding in children, yet endocrine responses vary widely. In a school-based pilot study (n = 11; aged 9–10 years), we examined whether the temporal structure of facilitator–child rhythmic interaction relates to pre–post changes in salivary oxytocin. Chest-mounted accelerometry (20 Hz) from the facilitator and each child during a 30-min drum circle was decomposed into a rhythm band (0.3–3 Hz) and a beat-related component. We estimated time-resolved directed coupling using transfer entropy (60-s windows, 5-s step) and computed directional asymmetry (ΔTE). Salivary oxytocin increased from pre to post (paired t-test, two-sided, p = 0.022), while cortisol showed no significant change. Individual oxytocin change was not strongly related to conventional summary indices of directional influence. Instead, oxytocin change was inversely associated with the longest sustained episode of significant unidirectional rhythmic influence (Spearman ρ = −0.72, p = 0.013). These exploratory findings suggest that prolonged unidirectional lock-in at the rhythmic timescale may be less conducive to oxytocin increases than dynamically shifting, bidirectional exchange. Larger preregistered studies are needed to determine whether temporal persistence of directional coupling provides a biologically relevant marker of engagement during group music-making.\u003c/p\u003e","manuscriptTitle":"Temporal persistence of unidirectional rhythmic coupling is inversely associated with salivary oxytocin change during facilitated drum circles in children","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-06 16:41:29","doi":"10.21203/rs.3.rs-9139008/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"145596652190458148191828969977058930539","date":"2026-04-30T01:59:04+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-27T10:59:52+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-27T10:49:19+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-09T10:34:35+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-07T19:19:37+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-04-07T15:35:30+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"67bbcca8-9b3d-4fb5-90c1-3c2ad17d2202","owner":[],"postedDate":"May 6th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"145596652190458148191828969977058930539","date":"2026-04-30T01:59:04+00:00","index":78,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":67278028,"name":"Biological sciences/Neuroscience"},{"id":67278029,"name":"Biological sciences/Physiology"},{"id":67278030,"name":"Biological sciences/Psychology"},{"id":67278031,"name":"Social science/Psychology"}],"tags":[],"updatedAt":"2026-05-06T16:41:29+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-06 16:41:29","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9139008","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9139008","identity":"rs-9139008","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}