Enhancing the regulatory function of the autonomic nervous system using sounds with inaudible high-frequency components

Enhancing the regulatory function of the autonomic nervous system using sounds with inaudible high-frequency components | 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 Enhancing the regulatory function of the autonomic nervous system using sounds with inaudible high-frequency components Koto Jogasaki, Norie Kawai, Emi Nishina, Manabu Honda This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6670151/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 22 Jul, 2025 Read the published version in Scientific Reports → Version 1 posted 11 You are reading this latest preprint version Abstract The dysregulation of the autonomic nervous system (ANS) activity notably contributes to the onset and progression of numerous diseases, including lifestyle-related and psychiatric disorders. This necessitates the development of effective nonpharmacological methods for regulating ANS function for therapeutic purposes and disease prevention. This study examined how the presence or absence of the inaudible high-frequency component (HFC) of sounds—which activates deep-brain structures—affects the ANS regulatory function. Under the N-back task condition, which requires concentration, exposure to sounds with HFC resulted in significantly higher sympathetic and parasympathetic nervous activities compared to sounds without HFC. Conversely, under the relaxation condition, the sounds with HFC significantly suppressed sympathetic nervous activity relative to sounds without HFC. Therefore, unlike pharmacological agents, which typically exert unidirectional effects on the ANS activity, sounds with HFC may flexibly adjust the sympathetic and parasympathetic nervous activities in response to situational demands. Biological sciences/Neuroscience/Peripheral nervous system/Autonomic nervous system Health sciences/Health care autonomic nervous system homeostasis hypersonic effect inaudible high-frequency sounds Figures Figure 1 Figure 2 Figure 3 Introduction The autonomic nervous system (ANS), comprising the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS), involuntarily regulates physiological functions to maintain homeostasis in response to environmental and situational demands. The dysregulation of ANS activity attributed to different factors—such as chronic SNS overactivation caused by aging, genetic predisposition, and physical and psychological stress—has been implicated in various physiological dysfunctions, particularly those related to the metabolic and circulatory systems [1]. Moreover, ANS imbalance significantly contributes to the onset and progression of numerous diseases, including lifestyle-related and psychiatric disorders [1]. Therefore, the development of effective nonpharmacological methods for regulating ANS function is promising for therapeutic purposes and disease prevention. The current study focused on the use of the hypersonic effect, a phenomenon previously reported by our group [2–11], as a potential nonpharmacological intervention. The hypersonic effect refers to a set of physiological and psychological responses elicited by a hypersonic sound, containing complex high-frequency components that are inaudible to humans, which exceeds the upper limit of human auditory perception (20 kHz). Our earlier findings showed that compared with sounds within the audible frequency range, exposure to hypersonic sounds significantly enhanced the alpha-band power in spontaneous electroencephalogram activity [3,4,6,7,8,10] and increases the regional cerebral blood flow of the deep-lying brain structures, such as the midbrain and hypothalamus [3,4,9]. In addition, the anterior cingulate cortex and the medial prefrontal cortex, which are the regions receiving input from monoaminergic reward-related circuits, are activated [9]. These findings explain that hypersonic sound induces psychological effects that promote pleasant sensations and emotional responses [3,4,8] and behavioral effects such as approach behavior [4,7,10,11]. Notably, a previous study reported that hypersonic sound significantly suppresses the increase in blood glucose levels during an oral glucose tolerance test, a key marker of glucose metabolism and diabetes risk [5]. Blood glucose homeostasis is regulated by intricate endocrine pathways involving hormones such as insulin, glucagon, and adrenaline, which are, in turn, modulated by higher-order systems including the ANS. Chronic SNS overactivation caused by stress adversely affects glucose regulation. Thus, the glucose-lowering effect may be mediated by suppressing the SNS activity [12]. Interestingly, this effect was more pronounced in older adults than in younger ones [5], thereby indicating a potential age-related difference in ANS responsiveness to hypersonic stimulation. Conversely, another study reported findings contradicting the aforementioned suppressive effect on SNS activity. In particular, exposure to hypersonic sound significantly enhanced performance on the N-back task, which is a cognitively demanding task requiring concentration and working memory [13]. Considering that a successful performance on such tasks may be associated with heightened arousal and increased SNS activation [14], this result indicates that hypersonic sound may also facilitate SNS activity under conditions requiring cognitive effort. Taken together, these seemingly contradictory findings raise the possibility that hypersonic sound modulates SNS activity in a context-dependent manner. In particular, under conditions requiring relaxation, it may promote restfulness by reducing SNS activity. Meanwhile, in cognitively demanding contexts, it may facilitate arousal and task engagement via SNS activation. Therefore, hypersonic sound may enhance the adaptive regulatory capacity of both SNS and PNS in accordance with situational demands, thereby representing a promising tool for ANS modulation. The current study aimed to examine the hypothesis that hypersonic sound enhances the ANS regulatory function. Thus, two distinct task conditions (one requiring mental tension and concentration and another promoting relaxation) were designed. During each task, the participants were exposed to either hypersonic sound or placebo sound, which was acoustically identical except for the absence of inaudible high-frequency components (HFC). The indices of the SNS and PNS activities were measured and compared to assess whether the effects of hypersonic sound varied based on the task context. Further, to explore potential age-related differences in responsiveness, the data were analyzed separately for the younger and older groups. Methods Participants Forty healthy adults (22 women, 18 men) aged 21–66 (mean age: 44.0 ± 18.5) years participated in this study. None of the participants reported the use of medications, including those prescribed for diabetes or dyslipidemia, which can affect ANS activity. To investigate age-related effects on ANS function, the participants were stratified into two age groups: the older group (n = 20; 12 women, 8 men; age range: 49–66 [mean: 61.3 ± 4.72] years) and the younger group (n = 20; 10 women, 10 men; age range: 21–48 [mean: 26.8 ± 7.69] years), as further described below. Auditory Stimuli and Presentation System Natural environmental sounds recorded in the primary forests of the Bornean tropical rainforest were used as auditory stimuli, consistent with a previous study [5]. These soundscapes comprised various natural sounds, including insect chirping, bird calling, and leaf rustling. Further, they were characterized by abundant high-frequency components inaudible to humans, exceeding 20 kHz, with complex temporal fluctuations on the millisecond scale. The average frequency bandwidth extended up to 150 kHz, with peaks reaching 200 kHz. A 20-min segment was used for the experimental playback. The following three auditory conditions were administered: Full-range sound (FRS): This was an unfiltered soundscape containing all frequency components. Based on a previous study, the hypersonic effect requires the presence of frequency components above 40 kHz that reach the body surface [6]. The FRS satisfied this requirement. High-cut sound (HCS): This was a low-pass filtered version of the original sound with a cutoff at 20 kHz (attenuation: −200 dB/octave). Hence, all components below this threshold were preserved, and inaudible HFC was eliminated. No-sound (NS): This was background laboratory noise (e.g., air conditioning) that was presented without any added auditory stimulus. Playback in the FRS and HCS conditions used the TASCAM DA3000 recorder (TEAC Corporation, Japan) with the 5.6448-MHz DSD format. Four OOHASHI Monitor Op.8 speakers (GAIA HSS-801, Action Research Co., Ltd., Japan), which is capable of an ultra-wideband output (20–120 kHz, − 10 dB), were used and supplemented by four super tweeters (HSST-01P, Action Research Co., Ltd., Japan; frequency response of 20–200 kHz). The setup aimed to replicate a natural rainforest acoustic environment, with speakers positioned at four points surrounding the participant (front-right, front-left, rear-right, and rear-left). The Supplementary Information shows the spectral power measurements at the ear level (height: 110 cm). Task Conditions A cognitively demanding condition (N-back task) and a relaxation condition were the two task conditions applied to regulate ANS activity. Both tasks were 5 minutes length. N-Back Task Condition The participants responded to a randomized sequence of four Japanese speech stimuli ( ue [up], shita [down], migi [right], and hidari [left]). Then, they identified whether the current stimulus matched the one presented N positions previously [15]—specifically two steps earlier in this study. The responses were recorded using the correct or incorrect buttons operated with the dominant hand. Response time and accuracy were emphasized. Prior to the experiment, a training session was conducted to determine the optimal stimulus interval, targeting an accuracy rate of 75–85%. Relaxation Condition The participants were instructed to release physical tension, breathe slowly and deeply, and focus on the sensation of relaxation. Eye closure was not restricted. However, continuous closing was discouraged. ANS Assessment To decrease measurement-induced stress, a low-intrusiveness protocol was adopted. Three indices were employed to assess the ANS activities. Details of the recording and analysis methods are provided in the Supplementary Information. Heart Rate Variability The high-frequency (HF; 0.15–0.4 Hz) component of heart rate variability (HRV) was used as a marker of PNS function [16,17]. During the 5-min N-back task and relaxation conditions, the R-R interval (RRI) data were recorded. The HF components were obtained by calculating the power spectral density within a range of 0.15–0.4-Hz using the Fast Fourier Transform of the RRI time-series data. Skin Conductance The tonic skin conductance level (SCL) of skin conductance (SC) time-series data, which represents general SNS activity, was adopted as the index of SNS activation [18]. The mean SCL over the 5-min period was calculated and utilized as the quantitative index of SNS activity. Skin Temperature The differential skin temperature (DST) between the nasal tip (more susceptible to sympathetic modulation) and forehead (less susceptible) was analyzed to cancel out environmental factors such as ambient temperature [19]. The 5-min average of the DST was used as an index of SNS activity. Experimental Procedure The Ethics Committee of the National Center of Neurology and Psychiatry approved this study (approval no. A2023-061). All participants provided a written informed consent. The current study was conducted in accordance with the Declaration of Helsinki. Each participant completed two experimental sessions on separate days, one for each task condition (N-back or relaxation). The order of conditions was counterbalanced across the participants. All sessions commenced at 10:00 AM to control for circadian influences. The participants were instructed to refrain from consuming caffeine and have adequate sleep prior to participation. Each experimental day comprised four sessions, with 10-min breaks between sessions. During the first three sessions, the FRS, HCS, and NS conditions were assigned in a counterbalanced manner. In the fourth session, the NS condition was consistently assigned. However, data from this session were excluded from the analysis. The inclusion of an additional NS session at the end, despite its exclusion from the analysis, aimed to decrease the potential confounding effects on ANS indices due to the psychological influences associated with the final session. In the N-back task condition, a 4-min baseline rest, followed by a 5-min period, during which either the sound stimulus (FRS or HCS) was presented, or silence (NS) was maintained. Feedback on task accuracy from the preceding session was provided before each N-back task condition. In the relaxation condition, the participants first watched a 2-min emotionally arousing video clip ( AKIRA , BANDAI VISUAL CO., LTD., Japan) to induce a heightened state of arousal, followed by the same sound manipulation and a subsequent 5-min relaxation period. To reduce environmental stress, plants were placed throughout the laboratory, and the equipment was arranged unobtrusively. The experimenter remained outside the room, observing the participants using audiovisual monitoring to maintain a nonintrusive presence. A separate glass-walled area served as a break room. Statistical Analysis All analyses were performed using EZR (Jichi Medical University, Japan) [20], a graphical interface for R designed for biostatistics. Data from participants with missing values or frequent arrhythmias were excluded from the analysis. Normality was assessed using the Shapiro–Wilk test, and outliers were identified using the Smirnov–Grubbs test. First, to examine whether differences in the task conditions set in this study influenced ANS indices and whether age-related changes in autonomic function were reflected in the measured indices, the mean values across the three sound conditions were calculated for each task condition and each participant. The participants (n = 40) were then divided into the older group and the younger group. For each ANS index (HF, SCL, and DST), a two-way repeated measures analysis of variance was conducted, with the task condition considered as a within-subject factor and the age group as a between-subject factor. Next, the effects of differences in sound conditions on each physiological index within each task condition were examined. The HF and SCL data were normalized by dividing the value for each sound condition by the mean value across the three sound conditions. In contrast, because the DST data fluctuate around zero, normalization by simple division would be inappropriate. Therefore, the mean forehead ST across all participants, task conditions, and sound conditions was first added to each DST value. Then, normalization was conducted by dividing the adjusted DST value of each sound condition by the mean of the three sound conditions. Repeated measures analysis of variance with the sound condition as a within-subject factor was conducted. Holm-corrected multiple comparisons were carried out for post hoc analysis between the sound conditions. In addition, to investigate the effects of age, similar analyses were performed individually for the older and younger groups. A p-value less than 0.05 was considered statistically significant. Results Data Validity and Characteristics of the Participants The HF data of HRV obtained from 37 participants (20 women and 17 men) aged 21–66 (mean age: 43.6 ± 18.4) years were valid. Among them, 18 were assigned to the older group (9 women, 9 men; 49–66 [mean: 61.2 ± 4.79] years) and 19 to the younger group (11 women, 8 men; 21–48 [mean: 27.1 ± 7.81] years). The SCL data of 39 participants (21 women and 18 men), who were aged 21–66 (mean: 44.2 ± 18.8) years, were valid. Of them, 20 were included in the older group (10 women, 10 men; mean age: 61.3 ± 4.72 years) and 19 in the younger group (11 women, 8 men; mean age: 26.2 ± 7.42 years). The DST data of 35 participants (20 women, 15 men), who were aged 21–66 years (mean age: 46.5 ± 18.4 years), were analyzed. The older group included 20 participants (10 women, 10 men; mean age: 61.3 ± 4.72 years), and the younger group comprised 15 participants (10 women, 5 men; mean age: 26.8 ± 8.04 years). Effect of the Task Condition and Age Group Figure 1 shows the mean values and standard errors (SEs) of the HF, SCL, and DST under the N-back and relaxation task conditions stratified by age group. These data were analyzed to assess the effects of cognitive load and age on ANS function. In this context, higher HF values reflected a greater PNS activity. Meanwhile, higher SCL and lower DST values indicated increased SNS activity. The task condition had a significant main effect on all three physiological indices. In particular, the HF in the N-back task condition was significantly lower than that in the relaxation condition (F (1, 32) = 8.76, p = 0.00576), thereby indicating a reduced PNS activity under the cognitive load. In contrast, the SCL was significantly higher in the N-back task condition compared with the relaxation condition (F (1, 37) = 16.5, p = 0.000240), which was consistent with increased SNS activity. Similarly, a significant decrease in the DST was observed during the N-back task condition compared with the relaxation condition (F (1, 26) = 6.47, p = 0.0173), thereby further supporting heightened sympathetic arousal during the cognitive task. The age group also exhibited main effects. The older group had significantly lower HF values than the younger group (F (1, 32) = 19.03, p = 0.000125), thereby indicating a reduction in baseline PNS activity with aging. A significant age-related difference was found for DST (F (1, 26) = 4.32, p = 0.0477), with the older group having lower values than the younger group, which suggests a higher baseline SNS activity. However, the age group did not have a significant effect on SCL (F (1, 37) = 0.103, p = 0.751), which indicated that the tonic SC did not differ significantly between the age groups. In contrast, the interaction effects between the task condition and age group were not statistically significant for any of the indices examined. In particular, the interaction terms for HF (F (1, 32) = 0.920, p = 0.345), SCL (F (1, 37) = 2.20, p = 0.146), and DST (F (1, 26) = 2.13, p = 0.157) did not reach statistical significance. Based on these results, although both task condition and age independently influenced autonomic responses, the patterns of task-related change were consistent across age groups. Effect of the Sound Condition Figures 2 and 3 present the mean values and SEs of the HF, SCL, and DST under each sound condition (FRS, HCS, and NS) for the N-back and relaxation conditions, respectively. The data of the whole group and the older and younger groups were presented, thereby allowing the examination of the influence of sound condition on both SNS and PNS activity. N-Back Task Condition As shown in Fig. 2 , the sound condition had a significant main effect on HF in the whole group (F (2, 62) = 5.53, p = 0.00619) and in the older group (F (2, 26) = 6.56, p = 0.00494). Post hoc comparisons revealed that both the FRS and NS conditions had significantly higher HF values than the HCS condition. In particular, in the whole group, the HF in the FRS (p = 0.0425) and NS (p = 0.00260) conditions was significantly higher than those in the HCS condition. However, the HF did not significantly differ between the FRS and NS conditions (p = 0.711). A similar pattern was observed in the older group, where the HF was significantly greater in the FRS (p = 0.0436) and NS (p = 0.00190) conditions than in the HCS condition. Nevertheless, there was no significant difference between the FRS and NS conditions (p = 0.512). The sound condition did not have a significant main effect on HF in the younger group (F (2, 32) = 2.79, p = 0.0763). Thus, the influence of HF sound components may be more evident in older adults than in younger ones. The sound condition had a significant main effect on the SCL only in the older group (F (2, 34) = 3.36, p = 0.0467). Post hoc analysis showed that SCL in the FRS (p = 0.0410) and NS (p = 0.0230) conditions were significantly higher relative to those in the HCS condition. However, no significant difference was observed between the FRS and NS conditions in terms of the SCL (p = 0.753). In contrast, the sound condition did not have a significant effect on the SCL in the whole group (F (2, 74) = 1.62, p = 0.206) and the younger group (F (2, 36) = 0.423, p = 0.658). The sound condition did not have significant main effects on the DST in any of the groups. In whole group, the DST did not differ significantly across the conditions (F (2, 60) = 0.0371, p = 0.964). Further, the DST did not have significant effects in the older (F (2, 34) = 0.266, p = 0.768) and younger (F (2, 26) = 1.33, p = 0.281) groups. Relaxation Condition As shown in Fig. 3 , the sound condition had a significant main effect on the DST in the whole group (F (2, 62) = 6.11, p = 0.00379). Post hoc comparisons showed that the DST was significantly higher in the FRS (p = 0.0100) and NS (p = 0.0200) conditions than in the HCS condition. Meanwhile, there was no significant difference in the DST between the FRS and NS conditions (p = 0.900). In the older group, although the main effect did not reach statistical significance (F (2, 36) = 3.16, p = 0.0542), the DST was more likely to be higher in the FRS condition than in the HCS condition (p = 0.100), thereby suggesting a possible age-related sensitivity. Nonetheless, there were no significant differences in the DST in the younger group (F (2, 22) = 2.79, p = 0.0834). The sound condition did not have significant effects on the HF during the relaxation condition in any of the groups. The F-values and p-values were as follows: whole group, F (2, 70) = 0.0894, p = 0.915; older group, F (2, 32) = 1.33, p = 0.280; and younger group, F (2, 36) = 2.95, p = 0.0649. Similarly, the sound condition did not significantly affect the SCL in any of the groups, as evidenced by the following values: whole group, F (2, 70) = 2.84, p = 0.0652; older group, F (2, 36) = 1.12, p = 0.337; and younger group, F (2, 36) = 0.361, p = 0.699. Discussion Effect of Hypersonic Sound on the Regulatory Function of the ANS To investigate the primary objective of this study—the effects of inaudible HFC—the FRS and HCS conditions were compared. Under the N-back task condition (Fig. 2 ), the HF values, which are indicative of PNS activity, were significantly higher in the FRS condition than in the HCS condition in both the whole group and the older group. Moreover, in the older group, the SCL, a marker of SNS activity, was also significantly elevated under the FRS condition. Conversely, under the relaxation condition (Fig. 3 ), the DST, an index of SNS activity, in the FRS condition was significantly higher than that in the HCS condition in the whole group, thereby indicating suppressed SNS activity. The older group exhibited a similar, although nonsignificant, trend. These findings suggest that the effects of inaudible HFC (FRS condition) versus their absence (HCS condition) on ANS activity vary based on task demands. In particular, under conditions requiring tension and concentration (N-back task), the FRS condition enhanced both the SNS and PNS activities. Meanwhile, under the relaxation condition, the FRS condition was more likely to suppress the SNS activity. These results support the study’s hypothesis that hypersonic sound regulates the SNS and PNS activities in a condition-dependent manner. Unlike pharmacological agents, which typically exert unidirectional effects on the ANS activity, hypersonic sound may flexibly adjust the SNS and PNS activities in response to situational demands. The underlying mechanisms should still be elucidated. However, previous studies have revealed that hypersonic sound increases cerebral blood flow to the hypothalamus, a key brain region responsible for regulating ANS output [9]. The hypothalamus integrates diverse physiological signals to maintain homeostasis and orchestrates the activities of both the SNS and PNS pathways. Therefore, the context-dependent modulation of ANS activity observed in the current study may be attributed to the enhanced hypothalamic function caused by increased cerebral blood flow induced by the hypersonic sound. Further, the absence of significant differences between the FRS and HCS conditions in the younger group and the evident effects observed in the older group are consistent with the findings of previous study showing that the glucose-suppressive effects of hypersonic sound were more evident in older individuals or those with elevated Hemoglobin A1c levels [5]. Considering that the regulatory function of the ANS declines with age [21], these results suggest that hypersonic sound may be particularly effective in individuals with impaired glucose tolerance or reduced ANS function. Moreover, the current findings imply that hypersonic sound may enhance the regulatory capacity of the ANS in populations with age-related or pathological decline and that it has minimal effects in individuals with preserved autonomic function. In addition, under the N-back task condition, the SNS and PNS indices significantly increased under the FRS condition relative to the HCS condition. A successful performance on tasks requiring sustained concentration—which is analogous to simultaneously pressing an accelerator and a brake—is dependent on the coordinated activation of both the SNS and PNS [22]. Hence, these results suggest that hypersonic sound may have supported engagement in the 5-min N-back task by facilitating a balanced autonomic state and preventing both under-arousal and excessive arousal. The SNS and PNS are traditionally viewed as antagonistic systems. However, their simultaneous coactivation under certain physiological or psychological conditions indicates a more nuanced and dynamic regulatory model [23]. In the relaxation condition, SNS activity significantly reduced under the FRS condition, as indicated by an increase in the DST. However, the HF, a PNS index, did not significantly increase. One possible explanation is that the PNS activity may have already been sufficiently elevated during the relaxation condition, resulting in a ceiling effect that masked further enhancements. Limitations in the Interpretation of the Results The finding that the SCL and DST—both considered indices of the SNS activity—did not respond uniformly to the sound conditions should be further investigated. One plausible explanation lies in the distinct response characteristics of the SC and ST. As noted in a previous study, the SCL, derived from the SC, reflects the tonic component and is highly sensitive to transient sweating responses triggered by psychological stress, thereby serving as a rapid indicator of increased SNS activity [18]. In contrast, the sympathetic vasoconstrictor nerve activity, which plays a key role in ST regulation, maintains a steady level of vascular tone at rest [24]. When SNS activity is suppressed, these nerves induce near-maximal vasodilation, making ST particularly sensitive to reductions in the SNS activity. These differences in response mechanisms may account for the finding that SNS activation during the N-back task condition was more sensitively captured by SCL. Meanwhile, SNS suppression during the relaxation condition was more clearly reflected by ST changes. This study primarily aimed to investigate the effects of inaudible HFC by comparing the FRS and HCS conditions. However, under the N-back task condition, both HF (a PNS index) and SCL (an SNS index) were significantly higher in the NS condition than in the HCS condition. Under the relaxation condition, the DST was significantly higher in the NS condition than in the HCS condition. Further, there were no significant differences between the FRS and NS conditions in any of these comparisons. These findings suggest that the differences observed between the FRS and HCS conditions may not be solely attributable to the presence of inaudible HFC in the FRS condition. Rather, they raise the possibility that the HCS condition—characterized by the presentation of only audible-range components—may suppress the ANS regulatory function. This finding is supported by previous studies that investigated the impact of HFC on brain activity, which similarly reported that the presentation of only audible-range sound (HCS condition) leads to reductions in alpha-band electroencephalogram power and decreased regional cerebral blood flow in the brainstem and thalamus compared with both the FRS and NS conditions [3,4]. The biological mechanisms underlying these effects remain unclear. However, we have previously reported that natural acoustic environments, such as tropical rainforests, are characterized by a rich presence of inaudible HFC, whereas modern urban environments significantly lack such features [25]. Further, the HCS condition, in which HFC were removed from the original sound source, is acoustically comparable to the audio quality of CDs and digital broadcasts, both of which are now widespread in modern urban environments as a part of conventional digital media. Considering these observations, it is essential to cautiously monitor and further investigate the potential physiological effects associated with inaudible HFC deficiency in contemporary acoustic environments. Appropriateness of the Task Conditions and Age Group Classification As shown in Fig. 1 , the task condition had a significant main effect across all measured indices. In particular, the HF, an index of PNS activity, was significantly lower during the N-back task condition than during the relaxation condition. Conversely, the SNS indices exhibited opposing patterns. Specifically, the SCL was significantly higher during the N-back task condition, and the DST was significantly lower. A higher HF value indicates a greater PNS activity. Meanwhile, elevated SCL and reduced DST values reflect an enhanced SNS activity. These results indicate that the N-back task induced a physiological state characterized by SNS dominance. Meanwhile, the relaxation condition elicited a PNS-dominant state, thereby showing that the two task conditions successfully elicited distinct patterns of the ANS activity. Regarding age-related differences, the HF and DST exhibited significant main effects in the age groups, with both indices significantly lower in the older group than in the younger group (Fig. 1 ). This pattern indicates that older participants had a reduced PNS activity and an increased SNS activity relative to their younger counterparts. These findings are consistent with previous evidence showing that aging is associated with diminished parasympathetic cardiovascular regulation, increased sympathetic tone, and an overall decline in ANS regulatory capacity [21]. Thus, the age group classifications and physiological indices used in the current study may be appropriate and effective for capturing age-related differences in the ANS function. In contrast, the SCL, which is another SNS-related index, did not exhibit a significant main effect in the age groups. Although both DST and SCL are indicators of the SNS activity, they are mediated via distinct neurophysiological pathways. Typically, postganglionic sympathetic neurons release norepinephrine, which acts on the target organs [26]. The sympathetic vasoconstrictor nerves regulating cutaneous blood flow—reflected by the DST—are primarily adrenergic, thereby releasing norepinephrine [26]. In contrast, the sympathetic innervation of the sweat glands, which contributes to SCL, is mediated by cholinergic neurons that release acetylcholine [26]. These neurochemical differences may account for the divergent age-related patterns observed between the two SNS indices. Future Directions The current study showed the effects of hypersonic sound on ANS regulation. This finding can provide important insights into the mechanisms underlying the hypersonic effect previously reported in the literature. The activation of brain regions such as the brainstem and hypothalamus regulates a broad range of physiological systems via the ANS, including the visceral organs, body surface, and vascular system. In this context, our results suggest that hypersonic sound may be a foundation for future medical applications aiming to treat and prevent disorders associated with ANS dysregulation or dysfunction. Future research should investigate the clinical potential of hypersonic sound in different conditions, such as lifestyle-related and stress-induced disorders, which are characterized by impaired ANS regulation. This research direction is in accordance with the emerging field of information medicine, which seeks to optimize environmental information input to regulate brain function [2,27]. Considering that the brain operates not only as a chemically driven organ but also as an information-processing system responsive to both internal and external stimuli, disruptions in the environmental information flow may impair neural processing and contribute to the development and progression of various psychiatric and neurological disorders. Information medicine represents a complementary approach to traditional pharmacological and surgical interventions, focusing on the information-processing aspects of brain function. By elucidating how environmental information influences neural activity, this field aims to develop nonpharmacological strategies for the treatment and prevention of psychiatric and neurological conditions. As discussed in the previous text, natural environments such as tropical rainforests—where human genetic and neural systems are believed to have evolved—are characterized by an abundance of inaudible HFC. If human evolution shaped the genetic and neural architectures to process such environmental information and enhance survival under these conditions, then an acoustic environment rich in inaudible HFC may represent an optimal state for the brain’s information-processing mechanisms. In contrast, the modern urban soundscape, which is significantly devoid of these HFC, may constitute a significant deviation from this evolutionary ideal. In light of the findings related to the hypersonic effect, advancing the development of information medicine approaches that aim to supplement contemporary urban environments with hypersonic sound is essential [2,27,28]. Declarations Competing interests The authors declare no competing interests. Funding This study was supported in part by JSPS KAKENHI Grant Number 19H01093 and 25K03075 for M.H., 23K11370 for E.N., and JST Moonshot R&D Grant Number JPMJMS2296 for M.H. Author Contribution K.J., N.K., and M.H. conceived and designed the experiment. N.K. and E.N. created the sound sources. K.J. acquired the data. K.J., N.K., and M.H. analyzed the data. K.J. and M.H. wrote the paper. All authors revised the paper. Acknowledgement We want to thank all of the participants of this study. We express our deepest gratitude to the late Dr. Osamu Ueno of the National Center of Neurology and Psychiatry for his invaluable contribution to this work. We also want to acknowledge Mr. Yusei Watanabe, Ms. Yuria Miyano, Ms. Kosa Fujimori, and Dr. Yuichi Yamashita of the National Center of Neurology and Psychiatry for providing technical support. The authors would like to thank Enago (www.enago.jp) for the English language review. Data Availability The datasets generated in this study will be provided upon reasonable request to the corresponding authors. References 1 Chrousos, G. P. Stress and disorders of the stress system. Nat Rev Endocrinol . 5 , 374-381 (2009). 2 Oohashi, T. Hypersonic Effect . (Iwanami Shoten, 2017) (in Japanese). 3 Oohashi, T. et al. Inaudible high-frequency sounds affect brain activity: hypersonic effect. J Neurophysiol . 83 , 3548-3558 (2000). 4 Oohashi, T., Nishina, E. & Honda, M. Multidisciplinary study on the hypersonic effect in Inter-Areal Coupling of Human Brain Function (ed. Shibasaki H. et al. ) 27-42 (Elsevier, 2002). 5 Kawai, N. et al. Positive effect of inaudible high-frequency components of sounds on glucose tolerance: a quasi-experimental crossover study. Sci Rep . 12 , 1-9 (2022). 6 Fukushima, A. et al. Frequencies of inaudible high-frequency sounds differentially affect brain activity: Positive and negative hypersonic effects. PLoS One . 9 (2014). 7 Oohashi, T. et al. The role of biological system other than auditory air-conduction in the emergence of the hypersonic effect. Brain Res . 1073-1074 , 339-347 (2006). 8 Oohashi, T., Nishina, E., Kawai, N., Fuwamoto, Y. & Imai, H. High-frequency sound above the audible range affects brain electric activity and sound perception. J Audio Eng Soc . 3207 , 1-25 (1991). 9 Honda, M. et al. Functional neuronal network subserving the hypersonic effect in ICA 2004. (ed. International Commission for Acoustics) 1751-1754 (2004). 10 Yagi, R., Nishina, E. & Oohashi, T. A method for behavioral evaluation of the “hypersonic effect”. Acoust Sci Technol . 24 , 197-200 (2003). 11 Yagi, R., Nishina, E., Honda, M. & Oohashi, T. Modulatory effect of inaudible high-frequency sounds on human acoustic perception. Neurosci Lett . 351 , 191-195 (2003). 12 Brunner, E. J. et al. Social inequality in coronary risk: Central obesity and the metabolic syndrome. Evidence from the Whitehall II study. Diabetologia . 40 , 1341-1349 (1997). 13 Suzuki, K. & Kawakatsu, M. The effect of exposing the inaudible ultrasonic components of the music during a recess on cognitive task in Acoustical Society of Japan. 1253-1254 (2012) (in Japanese). 14 Vincent, A., Craik, F. & Furedy, J. Relations among memory performance, mental workload and cardiovascular responses. Int J Psychophysiol . 23 , 181-198 (1996). 15 Jaeggi, S., Buschkuehl, M., Perrig, W. & Meier, B. The concurrent validity of the N-back task as a working memory measure. Memory . 18 , 394-412 (2010). 16 Camm, A. J. et al. Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Circulation . 93 , 1043-1065 (1996). 17 Shaffer, F. & Ginsberg, J. P. An overview of heart rate variability metrics and norms. Front Public Health . 5 (2017). 18 Leiner, D. J., Fahr, A. & Früh, H. EDA positive change: A simple algorithm for electrodermal activity to measure general audience arousal during media exposure. Comm Methods Meas . 6 , 237-250 (2012). 19 Yamakoshi, T., Kenta, M., Kobayashi, H., Gotoh, Y. & Hirose, H. Feasibility Study on Assessment of Driver's Stress from Differential Skin Temperature Measurement under Simulated Monotonous Driving. Trans Jpn Soc Med Biol Eng . 48 , 163-174 (2010) (in Japanese). 20 Kanda, Y. Investigation of the freely available easy-to-use software 'EZR' for medical statistics. Bone Marrow Transplant . 48 , 452-458 (2013). 21 Umetani, K., Singer, D., McCraty, R. & Atkinson, M. Twenty-four hour time domain heart rate variability and heart rate: relations to age and gender over nine decades. J Am Coll Cardiol . 31 , 593-601 (1998). 22 Hansen, A., Johnsen, B. & Thayer, J. Vagal influence on working memory and attention. Int J Psychophysiol . 48 , 263-274 (2003). 23 Christensen, J. et al. Diverse autonomic nervous system stress response patterns in childhood sensory modulation. Front Integr Neurosci . 14 (2020). 24 Korthuis, R. J. Skeletal Muscle Circulation . (Morgan & Claypool Life Sciences, 2011). 25 Nishina, E. & Oohashi, T. Study on the improvement of urban sound environment by the sound with in-audible high frequency components. J City Plann Inst Jpn . 42 , 139-144 (2007) (in Japanese). 26 McCorry, L. K. Physiology of the Autonomic Nervous System. Am J Pharm Educ . 71 (2007). 27 Honda, M. Information environment and brain function: A new concept of the environment for the brain in Neurodegenerative Disorders as Systemic Diseases (ed. Wada K) 279-294 (Springer, 2015). 28 Honda, M. et al. Non-pharmacological therapy for behavior and psychological symptoms of dementia (BPSD) utilizing the hypersonic effect: A pilot study. J Neurol Sci . 381 , 661-662 (2017). Additional Declarations No competing interests reported. Supplementary Files JogasakiSupplementaryInformationSubmission.pdf Cite Share Download PDF Status: Published Journal Publication published 22 Jul, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 06 Jun, 2025 Reviews received at journal 05 Jun, 2025 Reviews received at journal 03 Jun, 2025 Reviewers agreed at journal 27 May, 2025 Reviewers agreed at journal 27 May, 2025 Reviewers agreed at journal 27 May, 2025 Reviewers invited by journal 27 May, 2025 Editor invited by journal 27 May, 2025 Editor assigned by journal 21 May, 2025 Submission checks completed at journal 20 May, 2025 First submitted to journal 15 May, 2025 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. 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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-6670151","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":459798702,"identity":"441b73cd-63ac-4c78-96c8-cf7b2d1c0ba2","order_by":0,"name":"Koto Jogasaki","email":"","orcid":"","institution":"National Center of Neurology and Psychiatry","correspondingAuthor":false,"prefix":"","firstName":"Koto","middleName":"","lastName":"Jogasaki","suffix":""},{"id":459798703,"identity":"9e038a14-21b0-415f-8072-14966979f310","order_by":1,"name":"Norie Kawai","email":"","orcid":"","institution":"National Center of Neurology and Psychiatry","correspondingAuthor":false,"prefix":"","firstName":"Norie","middleName":"","lastName":"Kawai","suffix":""},{"id":459798704,"identity":"2773d984-6ec5-4e35-bc48-5fe5cda93517","order_by":2,"name":"Emi Nishina","email":"","orcid":"","institution":"The Open University of Japan","correspondingAuthor":false,"prefix":"","firstName":"Emi","middleName":"","lastName":"Nishina","suffix":""},{"id":459798705,"identity":"03a95166-0e01-4dcd-a330-b2830bfdc459","order_by":3,"name":"Manabu Honda","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAs0lEQVRIiWNgGAWjYBACAyCWYKiA89mI1XKGZC2MbaQ4zJy99+CNn/PuyJtLNzC/+MDAl0dQi2XPuWTL3m3PDHfOOcBmOYOBrZiww27kmEnwbjucYHAjgc2Yh4EtsYEYLZJ/55CqRZq3AayF+TFxWs6cMbaWOXbYcMOdg22MMwyI8cvxHsObb2oOyxvcbj784UPFMcIhhgDA2JFgMDiWQIoWBuYPDAw1pGgZBaNgFIyCEQIAG7s9i6Hw9rAAAAAASUVORK5CYII=","orcid":"","institution":"National Center of Neurology and Psychiatry","correspondingAuthor":true,"prefix":"","firstName":"Manabu","middleName":"","lastName":"Honda","suffix":""}],"badges":[],"createdAt":"2025-05-15 07:53:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6670151/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6670151/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-11190-9","type":"published","date":"2025-07-23T00:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":83501885,"identity":"aac60202-d6cd-44f8-824e-7535ca896a6c","added_by":"auto","created_at":"2025-05-27 13:40:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":11233,"visible":true,"origin":"","legend":"\u003cp\u003eMean values of the HF, SCL, and DST for each task condition (N-back and relaxation) across the older and younger groups. The error bars represent the standard error of the mean. A p-value less than 0.05 was considered statistically significant. The blue and pink bars correspond to the N-back and relaxation conditions, respectively. The task condition exhibited significant main effects in all indices. In addition, the age group had significant main effects on the HF and DST. No significant interaction effects were observed between the task condition and age group for any of the indices.\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6670151/v1/bda49e3135a4f57c00208420.png"},{"id":83501890,"identity":"32fffb1d-1d16-4c58-a850-562bcce135d8","added_by":"auto","created_at":"2025-05-27 13:40:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":15109,"visible":true,"origin":"","legend":"\u003cp\u003eMean values of the HF, SCL, and DST during the N-back task condition across the whole group, older group, and younger group. The error bars represent the standard error of the mean. A p-value less than 0.05 was considered statistically significant. The blue, pink, and gray bars correspond to the high-cut sound (HCS), full-range sound (FRS), and no-sound (NS) conditions, respectively. For the HF, the significant main effects of the sound condition were detected in both the whole group and the older group. Post hoc comparisons with Holm’s correction indicated that the HF values were significantly higher in the FRS condition than in the HCS condition (whole group: p = 0.0425; older group: p = 0.0436). For SCL, the significant main effect of the sound condition was observed only in the older group, with higher values observed in the FRS condition than in the HCS condition (p = 0.0410). The sound condition did not have significant main effects on the DST in any of the groups.\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6670151/v1/82e4c72e9d0c0f0c0a66e369.png"},{"id":83501886,"identity":"707f635a-bc6a-4af6-b026-c89a1e6ef06f","added_by":"auto","created_at":"2025-05-27 13:40:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":14114,"visible":true,"origin":"","legend":"\u003cp\u003eMean values of the HF, SCL, and DST during the relaxation condition across the whole group, older group, and younger group. The error bars represent the standard error of the mean. A p-value less than 0.05 was considered statistically significant. The blue, pink, and gray bars correspond to the high-cut sound (HCS), full-range sound (FRS), and no-sound (NS) conditions, respectively. For DST, the significant main effect of the sound condition was observed in the whole group. Post hoc comparisons with Holm’s correction showed that the DST values were significantly higher in the FRS condition than in the HCS condition (p = 0.0100). In the older group, although the main effect of the sound condition did not reach statistical significance, the DST values were more likely to be higher in the FRS condition than in the HCS condition (p = 0.100). The sound condition did not have significant main effects on the HF or SCL in any of the groups during the relaxation condition.\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6670151/v1/98d792da55b64d0576696048.png"},{"id":87748124,"identity":"f4485250-85d5-421b-ba3a-65112c83cd82","added_by":"auto","created_at":"2025-07-28 14:31:03","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":567103,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6670151/v1/7a9da12a-c351-4292-9020-4cc95cbad4d1.pdf"},{"id":83501889,"identity":"6decbe92-2615-469c-bfb5-4c486f0c71de","added_by":"auto","created_at":"2025-05-27 13:40:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":384996,"visible":true,"origin":"","legend":"","description":"","filename":"JogasakiSupplementaryInformationSubmission.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6670151/v1/94fdbb49aacc0828a745e799.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Enhancing the regulatory function of the autonomic nervous system using sounds with inaudible high-frequency components","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe autonomic nervous system (ANS), comprising the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS), involuntarily regulates physiological functions to maintain homeostasis in response to environmental and situational demands. The dysregulation of ANS activity attributed to different factors\u0026mdash;such as chronic SNS overactivation caused by aging, genetic predisposition, and physical and psychological stress\u0026mdash;has been implicated in various physiological dysfunctions, particularly those related to the metabolic and circulatory systems [1]. Moreover, ANS imbalance significantly contributes to the onset and progression of numerous diseases, including lifestyle-related and psychiatric disorders [1]. Therefore, the development of effective nonpharmacological methods for regulating ANS function is promising for therapeutic purposes and disease prevention.\u003c/p\u003e \u003cp\u003eThe current study focused on the use of the hypersonic effect, a phenomenon previously reported by our group [2\u0026ndash;11], as a potential nonpharmacological intervention. The hypersonic effect refers to a set of physiological and psychological responses elicited by a hypersonic sound, containing complex high-frequency components that are inaudible to humans, which exceeds the upper limit of human auditory perception (20 kHz). Our earlier findings showed that compared with sounds within the audible frequency range, exposure to hypersonic sounds significantly enhanced the alpha-band power in spontaneous electroencephalogram activity [3,4,6,7,8,10] and increases the regional cerebral blood flow of the deep-lying brain structures, such as the midbrain and hypothalamus [3,4,9]. In addition, the anterior cingulate cortex and the medial prefrontal cortex, which are the regions receiving input from monoaminergic reward-related circuits, are activated [9]. These findings explain that hypersonic sound induces psychological effects that promote pleasant sensations and emotional responses [3,4,8] and behavioral effects such as approach behavior [4,7,10,11].\u003c/p\u003e \u003cp\u003eNotably, a previous study reported that hypersonic sound significantly suppresses the increase in blood glucose levels during an oral glucose tolerance test, a key marker of glucose metabolism and diabetes risk [5]. Blood glucose homeostasis is regulated by intricate endocrine pathways involving hormones such as insulin, glucagon, and adrenaline, which are, in turn, modulated by higher-order systems including the ANS. Chronic SNS overactivation caused by stress adversely affects glucose regulation. Thus, the glucose-lowering effect may be mediated by suppressing the SNS activity [12]. Interestingly, this effect was more pronounced in older adults than in younger ones [5], thereby indicating a potential age-related difference in ANS responsiveness to hypersonic stimulation.\u003c/p\u003e \u003cp\u003eConversely, another study reported findings contradicting the aforementioned suppressive effect on SNS activity. In particular, exposure to hypersonic sound significantly enhanced performance on the N-back task, which is a cognitively demanding task requiring concentration and working memory [13]. Considering that a successful performance on such tasks may be associated with heightened arousal and increased SNS activation [14], this result indicates that hypersonic sound may also facilitate SNS activity under conditions requiring cognitive effort.\u003c/p\u003e \u003cp\u003eTaken together, these seemingly contradictory findings raise the possibility that hypersonic sound modulates SNS activity in a context-dependent manner. In particular, under conditions requiring relaxation, it may promote restfulness by reducing SNS activity. Meanwhile, in cognitively demanding contexts, it may facilitate arousal and task engagement via SNS activation. Therefore, hypersonic sound may enhance the adaptive regulatory capacity of both SNS and PNS in accordance with situational demands, thereby representing a promising tool for ANS modulation.\u003c/p\u003e \u003cp\u003eThe current study aimed to examine the hypothesis that hypersonic sound enhances the ANS regulatory function. Thus, two distinct task conditions (one requiring mental tension and concentration and another promoting relaxation) were designed. During each task, the participants were exposed to either hypersonic sound or placebo sound, which was acoustically identical except for the absence of inaudible high-frequency components (HFC). The indices of the SNS and PNS activities were measured and compared to assess whether the effects of hypersonic sound varied based on the task context. Further, to explore potential age-related differences in responsiveness, the data were analyzed separately for the younger and older groups.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eParticipants\u003c/p\u003e \u003cp\u003eForty healthy adults (22 women, 18 men) aged 21\u0026ndash;66 (mean age: 44.0\u0026thinsp;\u0026plusmn;\u0026thinsp;18.5) years participated in this study. None of the participants reported the use of medications, including those prescribed for diabetes or dyslipidemia, which can affect ANS activity. To investigate age-related effects on ANS function, the participants were stratified into two age groups: the older group (n\u0026thinsp;=\u0026thinsp;20; 12 women, 8 men; age range: 49\u0026ndash;66 [mean: 61.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.72] years) and the younger group (n\u0026thinsp;=\u0026thinsp;20; 10 women, 10 men; age range: 21\u0026ndash;48 [mean: 26.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.69] years), as further described below.\u003c/p\u003e \u003cp\u003eAuditory Stimuli and Presentation System\u003c/p\u003e \u003cp\u003eNatural environmental sounds recorded in the primary forests of the Bornean tropical rainforest were used as auditory stimuli, consistent with a previous study [5]. These soundscapes comprised various natural sounds, including insect chirping, bird calling, and leaf rustling. Further, they were characterized by abundant high-frequency components inaudible to humans, exceeding 20 kHz, with complex temporal fluctuations on the millisecond scale. The average frequency bandwidth extended up to 150 kHz, with peaks reaching 200 kHz. A 20-min segment was used for the experimental playback.\u003c/p\u003e \u003cp\u003eThe following three auditory conditions were administered:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eFull-range sound (FRS): This was an unfiltered soundscape containing all frequency components. Based on a previous study, the hypersonic effect requires the presence of frequency components above 40 kHz that reach the body surface [6]. The FRS satisfied this requirement.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eHigh-cut sound (HCS): This was a low-pass filtered version of the original sound with a cutoff at 20 kHz (attenuation: \u0026minus;200 dB/octave). Hence, all components below this threshold were preserved, and inaudible HFC was eliminated.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eNo-sound (NS): This was background laboratory noise (e.g., air conditioning) that was presented without any added auditory stimulus.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003ePlayback in the FRS and HCS conditions used the TASCAM DA3000 recorder (TEAC Corporation, Japan) with the 5.6448-MHz DSD format. Four OOHASHI Monitor Op.8 speakers (GAIA HSS-801, Action Research Co., Ltd., Japan), which is capable of an ultra-wideband output (20\u0026ndash;120 kHz, \u0026minus;\u0026thinsp;10 dB), were used and supplemented by four super tweeters (HSST-01P, Action Research Co., Ltd., Japan; frequency response of 20\u0026ndash;200 kHz). The setup aimed to replicate a natural rainforest acoustic environment, with speakers positioned at four points surrounding the participant (front-right, front-left, rear-right, and rear-left). The Supplementary Information shows the spectral power measurements at the ear level (height: 110 cm).\u003c/p\u003e \u003cp\u003eTask Conditions\u003c/p\u003e \u003cp\u003eA cognitively demanding condition (N-back task) and a relaxation condition were the two task conditions applied to regulate ANS activity. Both tasks were 5 minutes length.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eN-Back Task Condition\u003c/strong\u003e \u003cp\u003eThe participants responded to a randomized sequence of four Japanese speech stimuli (\u003cem\u003eue\u003c/em\u003e [up], \u003cem\u003eshita\u003c/em\u003e [down], \u003cem\u003emigi\u003c/em\u003e [right], and \u003cem\u003ehidari\u003c/em\u003e [left]). Then, they identified whether the current stimulus matched the one presented N positions previously [15]\u0026mdash;specifically two steps earlier in this study. The responses were recorded using the correct or incorrect buttons operated with the dominant hand. Response time and accuracy were emphasized. Prior to the experiment, a training session was conducted to determine the optimal stimulus interval, targeting an accuracy rate of 75\u0026ndash;85%.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eRelaxation Condition\u003c/strong\u003e \u003cp\u003e The participants were instructed to release physical tension, breathe slowly and deeply, and focus on the sensation of relaxation. Eye closure was not restricted. However, continuous closing was discouraged.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eANS Assessment\u003c/p\u003e \u003cp\u003eTo decrease measurement-induced stress, a low-intrusiveness protocol was adopted. Three indices were employed to assess the ANS activities. Details of the recording and analysis methods are provided in the Supplementary Information.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eHeart Rate Variability\u003c/strong\u003e \u003cp\u003eThe high-frequency (HF; 0.15\u0026ndash;0.4 Hz) component of heart rate variability (HRV) was used as a marker of PNS function [16,17]. During the 5-min N-back task and relaxation conditions, the R-R interval (RRI) data were recorded. The HF components were obtained by calculating the power spectral density within a range of 0.15\u0026ndash;0.4-Hz using the Fast Fourier Transform of the RRI time-series data.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSkin Conductance\u003c/strong\u003e \u003cp\u003eThe tonic skin conductance level (SCL) of skin conductance (SC) time-series data, which represents general SNS activity, was adopted as the index of SNS activation [18]. The mean SCL over the 5-min period was calculated and utilized as the quantitative index of SNS activity.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSkin Temperature\u003c/strong\u003e \u003cp\u003eThe differential skin temperature (DST) between the nasal tip (more susceptible to sympathetic modulation) and forehead (less susceptible) was analyzed to cancel out environmental factors such as ambient temperature [19]. The 5-min average of the DST was used as an index of SNS activity.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eExperimental Procedure\u003c/p\u003e \u003cp\u003eThe Ethics Committee of the National Center of Neurology and Psychiatry approved this study (approval no. A2023-061). All participants provided a written informed consent. The current study was conducted in accordance with the Declaration of Helsinki.\u003c/p\u003e \u003cp\u003eEach participant completed two experimental sessions on separate days, one for each task condition (N-back or relaxation). The order of conditions was counterbalanced across the participants. All sessions commenced at 10:00 AM to control for circadian influences. The participants were instructed to refrain from consuming caffeine and have adequate sleep prior to participation. Each experimental day comprised four sessions, with 10-min breaks between sessions. During the first three sessions, the FRS, HCS, and NS conditions were assigned in a counterbalanced manner. In the fourth session, the NS condition was consistently assigned. However, data from this session were excluded from the analysis. The inclusion of an additional NS session at the end, despite its exclusion from the analysis, aimed to decrease the potential confounding effects on ANS indices due to the psychological influences associated with the final session. In the N-back task condition, a 4-min baseline rest, followed by a 5-min period, during which either the sound stimulus (FRS or HCS) was presented, or silence (NS) was maintained. Feedback on task accuracy from the preceding session was provided before each N-back task condition. In the relaxation condition, the participants first watched a 2-min emotionally arousing video clip (\u003cem\u003eAKIRA\u003c/em\u003e, BANDAI VISUAL CO., LTD., Japan) to induce a heightened state of arousal, followed by the same sound manipulation and a subsequent 5-min relaxation period.\u003c/p\u003e \u003cp\u003eTo reduce environmental stress, plants were placed throughout the laboratory, and the equipment was arranged unobtrusively. The experimenter remained outside the room, observing the participants using audiovisual monitoring to maintain a nonintrusive presence. A separate glass-walled area served as a break room.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eAll analyses were performed using EZR (Jichi Medical University, Japan) [20], a graphical interface for R designed for biostatistics. Data from participants with missing values or frequent arrhythmias were excluded from the analysis. Normality was assessed using the Shapiro\u0026ndash;Wilk test, and outliers were identified using the Smirnov\u0026ndash;Grubbs test.\u003c/p\u003e \u003cp\u003e First, to examine whether differences in the task conditions set in this study influenced ANS indices and whether age-related changes in autonomic function were reflected in the measured indices, the mean values across the three sound conditions were calculated for each task condition and each participant. The participants (n\u0026thinsp;=\u0026thinsp;40) were then divided into the older group and the younger group. For each ANS index (HF, SCL, and DST), a two-way repeated measures analysis of variance was conducted, with the task condition considered as a within-subject factor and the age group as a between-subject factor.\u003c/p\u003e \u003cp\u003eNext, the effects of differences in sound conditions on each physiological index within each task condition were examined. The HF and SCL data were normalized by dividing the value for each sound condition by the mean value across the three sound conditions. In contrast, because the DST data fluctuate around zero, normalization by simple division would be inappropriate. Therefore, the mean forehead ST across all participants, task conditions, and sound conditions was first added to each DST value. Then, normalization was conducted by dividing the adjusted DST value of each sound condition by the mean of the three sound conditions. Repeated measures analysis of variance with the sound condition as a within-subject factor was conducted. Holm-corrected multiple comparisons were carried out for post hoc analysis between the sound conditions. In addition, to investigate the effects of age, similar analyses were performed individually for the older and younger groups. A p-value less than 0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eData Validity and Characteristics of the Participants\u003c/p\u003e \u003cp\u003eThe HF data of HRV obtained from 37 participants (20 women and 17 men) aged 21\u0026ndash;66 (mean age: 43.6\u0026thinsp;\u0026plusmn;\u0026thinsp;18.4) years were valid. Among them, 18 were assigned to the older group (9 women, 9 men; 49\u0026ndash;66 [mean: 61.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.79] years) and 19 to the younger group (11 women, 8 men; 21\u0026ndash;48 [mean: 27.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.81] years).\u003c/p\u003e \u003cp\u003eThe SCL data of 39 participants (21 women and 18 men), who were aged 21\u0026ndash;66 (mean: 44.2\u0026thinsp;\u0026plusmn;\u0026thinsp;18.8) years, were valid. Of them, 20 were included in the older group (10 women, 10 men; mean age: 61.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.72 years) and 19 in the younger group (11 women, 8 men; mean age: 26.2\u0026thinsp;\u0026plusmn;\u0026thinsp;7.42 years).\u003c/p\u003e \u003cp\u003eThe DST data of 35 participants (20 women, 15 men), who were aged 21\u0026ndash;66 years (mean age: 46.5\u0026thinsp;\u0026plusmn;\u0026thinsp;18.4 years), were analyzed. The older group included 20 participants (10 women, 10 men; mean age: 61.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.72 years), and the younger group comprised 15 participants (10 women, 5 men; mean age: 26.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.04 years).\u003c/p\u003e \u003cp\u003eEffect of the Task Condition and Age Group\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the mean values and standard errors (SEs) of the HF, SCL, and DST under the N-back and relaxation task conditions stratified by age group. These data were analyzed to assess the effects of cognitive load and age on ANS function. In this context, higher HF values reflected a greater PNS activity. Meanwhile, higher SCL and lower DST values indicated increased SNS activity.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe task condition had a significant main effect on all three physiological indices. In particular, the HF in the N-back task condition was significantly lower than that in the relaxation condition (F (1, 32)\u0026thinsp;=\u0026thinsp;8.76, p\u0026thinsp;=\u0026thinsp;0.00576), thereby indicating a reduced PNS activity under the cognitive load. In contrast, the SCL was significantly higher in the N-back task condition compared with the relaxation condition (F (1, 37)\u0026thinsp;=\u0026thinsp;16.5, p\u0026thinsp;=\u0026thinsp;0.000240), which was consistent with increased SNS activity. Similarly, a significant decrease in the DST was observed during the N-back task condition compared with the relaxation condition (F (1, 26)\u0026thinsp;=\u0026thinsp;6.47, p\u0026thinsp;=\u0026thinsp;0.0173), thereby further supporting heightened sympathetic arousal during the cognitive task.\u003c/p\u003e \u003cp\u003eThe age group also exhibited main effects. The older group had significantly lower HF values than the younger group (F (1, 32)\u0026thinsp;=\u0026thinsp;19.03, p\u0026thinsp;=\u0026thinsp;0.000125), thereby indicating a reduction in baseline PNS activity with aging. A significant age-related difference was found for DST (F (1, 26)\u0026thinsp;=\u0026thinsp;4.32, p\u0026thinsp;=\u0026thinsp;0.0477), with the older group having lower values than the younger group, which suggests a higher baseline SNS activity. However, the age group did not have a significant effect on SCL (F (1, 37)\u0026thinsp;=\u0026thinsp;0.103, p\u0026thinsp;=\u0026thinsp;0.751), which indicated that the tonic SC did not differ significantly between the age groups.\u003c/p\u003e \u003cp\u003eIn contrast, the interaction effects between the task condition and age group were not statistically significant for any of the indices examined. In particular, the interaction terms for HF (F (1, 32)\u0026thinsp;=\u0026thinsp;0.920, p\u0026thinsp;=\u0026thinsp;0.345), SCL (F (1, 37)\u0026thinsp;=\u0026thinsp;2.20, p\u0026thinsp;=\u0026thinsp;0.146), and DST (F (1, 26)\u0026thinsp;=\u0026thinsp;2.13, p\u0026thinsp;=\u0026thinsp;0.157) did not reach statistical significance. Based on these results, although both task condition and age independently influenced autonomic responses, the patterns of task-related change were consistent across age groups.\u003c/p\u003e \u003cp\u003eEffect of the Sound Condition\u003c/p\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e present the mean values and SEs of the HF, SCL, and DST under each sound condition (FRS, HCS, and NS) for the N-back and relaxation conditions, respectively. The data of the whole group and the older and younger groups were presented, thereby allowing the examination of the influence of sound condition on both SNS and PNS activity.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eN-Back Task Condition\u003c/strong\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the sound condition had a significant main effect on HF in the whole group (F (2, 62)\u0026thinsp;=\u0026thinsp;5.53, p\u0026thinsp;=\u0026thinsp;0.00619) and in the older group (F (2, 26)\u0026thinsp;=\u0026thinsp;6.56, p\u0026thinsp;=\u0026thinsp;0.00494). Post hoc comparisons revealed that both the FRS and NS conditions had significantly higher HF values than the HCS condition. In particular, in the whole group, the HF in the FRS (p\u0026thinsp;=\u0026thinsp;0.0425) and NS (p\u0026thinsp;=\u0026thinsp;0.00260) conditions was significantly higher than those in the HCS condition. However, the HF did not significantly differ between the FRS and NS conditions (p\u0026thinsp;=\u0026thinsp;0.711). A similar pattern was observed in the older group, where the HF was significantly greater in the FRS (p\u0026thinsp;=\u0026thinsp;0.0436) and NS (p\u0026thinsp;=\u0026thinsp;0.00190) conditions than in the HCS condition. Nevertheless, there was no significant difference between the FRS and NS conditions (p\u0026thinsp;=\u0026thinsp;0.512). The sound condition did not have a significant main effect on HF in the younger group (F (2, 32)\u0026thinsp;=\u0026thinsp;2.79, p\u0026thinsp;=\u0026thinsp;0.0763). Thus, the influence of HF sound components may be more evident in older adults than in younger ones.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eThe sound condition had a significant main effect on the SCL only in the older group (F (2, 34)\u0026thinsp;=\u0026thinsp;3.36, p\u0026thinsp;=\u0026thinsp;0.0467). Post hoc analysis showed that SCL in the FRS (p\u0026thinsp;=\u0026thinsp;0.0410) and NS (p\u0026thinsp;=\u0026thinsp;0.0230) conditions were significantly higher relative to those in the HCS condition. However, no significant difference was observed between the FRS and NS conditions in terms of the SCL (p\u0026thinsp;=\u0026thinsp;0.753). In contrast, the sound condition did not have a significant effect on the SCL in the whole group (F (2, 74)\u0026thinsp;=\u0026thinsp;1.62, p\u0026thinsp;=\u0026thinsp;0.206) and the younger group (F (2, 36)\u0026thinsp;=\u0026thinsp;0.423, p\u0026thinsp;=\u0026thinsp;0.658).\u003c/p\u003e \u003cp\u003eThe sound condition did not have significant main effects on the DST in any of the groups. In whole group, the DST did not differ significantly across the conditions (F (2, 60)\u0026thinsp;=\u0026thinsp;0.0371, p\u0026thinsp;=\u0026thinsp;0.964). Further, the DST did not have significant effects in the older (F (2, 34)\u0026thinsp;=\u0026thinsp;0.266, p\u0026thinsp;=\u0026thinsp;0.768) and younger (F (2, 26)\u0026thinsp;=\u0026thinsp;1.33, p\u0026thinsp;=\u0026thinsp;0.281) groups.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eRelaxation Condition\u003c/strong\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the sound condition had a significant main effect on the DST in the whole group (F (2, 62)\u0026thinsp;=\u0026thinsp;6.11, p\u0026thinsp;=\u0026thinsp;0.00379). Post hoc comparisons showed that the DST was significantly higher in the FRS (p\u0026thinsp;=\u0026thinsp;0.0100) and NS (p\u0026thinsp;=\u0026thinsp;0.0200) conditions than in the HCS condition. Meanwhile, there was no significant difference in the DST between the FRS and NS conditions (p\u0026thinsp;=\u0026thinsp;0.900). In the older group, although the main effect did not reach statistical significance (F (2, 36)\u0026thinsp;=\u0026thinsp;3.16, p\u0026thinsp;=\u0026thinsp;0.0542), the DST was more likely to be higher in the FRS condition than in the HCS condition (p\u0026thinsp;=\u0026thinsp;0.100), thereby suggesting a possible age-related sensitivity. Nonetheless, there were no significant differences in the DST in the younger group (F (2, 22)\u0026thinsp;=\u0026thinsp;2.79, p\u0026thinsp;=\u0026thinsp;0.0834).\u003c/p\u003e \u003c/p\u003e \u003cp\u003eThe sound condition did not have significant effects on the HF during the relaxation condition in any of the groups. The F-values and p-values were as follows: whole group, F (2, 70)\u0026thinsp;=\u0026thinsp;0.0894, p\u0026thinsp;=\u0026thinsp;0.915; older group, F (2, 32)\u0026thinsp;=\u0026thinsp;1.33, p\u0026thinsp;=\u0026thinsp;0.280; and younger group, F (2, 36)\u0026thinsp;=\u0026thinsp;2.95, p\u0026thinsp;=\u0026thinsp;0.0649. Similarly, the sound condition did not significantly affect the SCL in any of the groups, as evidenced by the following values: whole group, F (2, 70)\u0026thinsp;=\u0026thinsp;2.84, p\u0026thinsp;=\u0026thinsp;0.0652; older group, F (2, 36)\u0026thinsp;=\u0026thinsp;1.12, p\u0026thinsp;=\u0026thinsp;0.337; and younger group, F (2, 36)\u0026thinsp;=\u0026thinsp;0.361, p\u0026thinsp;=\u0026thinsp;0.699.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eEffect of Hypersonic Sound on the Regulatory Function of the ANS\u003c/p\u003e \u003cp\u003eTo investigate the primary objective of this study\u0026mdash;the effects of inaudible HFC\u0026mdash;the FRS and HCS conditions were compared.\u003c/p\u003e \u003cp\u003eUnder the N-back task condition (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), the HF values, which are indicative of PNS activity, were significantly higher in the FRS condition than in the HCS condition in both the whole group and the older group. Moreover, in the older group, the SCL, a marker of SNS activity, was also significantly elevated under the FRS condition. Conversely, under the relaxation condition (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), the DST, an index of SNS activity, in the FRS condition was significantly higher than that in the HCS condition in the whole group, thereby indicating suppressed SNS activity. The older group exhibited a similar, although nonsignificant, trend. These findings suggest that the effects of inaudible HFC (FRS condition) versus their absence (HCS condition) on ANS activity vary based on task demands. In particular, under conditions requiring tension and concentration (N-back task), the FRS condition enhanced both the SNS and PNS activities. Meanwhile, under the relaxation condition, the FRS condition was more likely to suppress the SNS activity. These results support the study\u0026rsquo;s hypothesis that hypersonic sound regulates the SNS and PNS activities in a condition-dependent manner. Unlike pharmacological agents, which typically exert unidirectional effects on the ANS activity, hypersonic sound may flexibly adjust the SNS and PNS activities in response to situational demands.\u003c/p\u003e \u003cp\u003eThe underlying mechanisms should still be elucidated. However, previous studies have revealed that hypersonic sound increases cerebral blood flow to the hypothalamus, a key brain region responsible for regulating ANS output [9]. The hypothalamus integrates diverse physiological signals to maintain homeostasis and orchestrates the activities of both the SNS and PNS pathways. Therefore, the context-dependent modulation of ANS activity observed in the current study may be attributed to the enhanced hypothalamic function caused by increased cerebral blood flow induced by the hypersonic sound.\u003c/p\u003e \u003cp\u003eFurther, the absence of significant differences between the FRS and HCS conditions in the younger group and the evident effects observed in the older group are consistent with the findings of previous study showing that the glucose-suppressive effects of hypersonic sound were more evident in older individuals or those with elevated Hemoglobin A1c levels [5]. Considering that the regulatory function of the ANS declines with age [21], these results suggest that hypersonic sound may be particularly effective in individuals with impaired glucose tolerance or reduced ANS function. Moreover, the current findings imply that hypersonic sound may enhance the regulatory capacity of the ANS in populations with age-related or pathological decline and that it has minimal effects in individuals with preserved autonomic function.\u003c/p\u003e \u003cp\u003eIn addition, under the N-back task condition, the SNS and PNS indices significantly increased under the FRS condition relative to the HCS condition. A successful performance on tasks requiring sustained concentration\u0026mdash;which is analogous to simultaneously pressing an accelerator and a brake\u0026mdash;is dependent on the coordinated activation of both the SNS and PNS [22]. Hence, these results suggest that hypersonic sound may have supported engagement in the 5-min N-back task by facilitating a balanced autonomic state and preventing both under-arousal and excessive arousal. The SNS and PNS are traditionally viewed as antagonistic systems. However, their simultaneous coactivation under certain physiological or psychological conditions indicates a more nuanced and dynamic regulatory model [23].\u003c/p\u003e \u003cp\u003eIn the relaxation condition, SNS activity significantly reduced under the FRS condition, as indicated by an increase in the DST. However, the HF, a PNS index, did not significantly increase. One possible explanation is that the PNS activity may have already been sufficiently elevated during the relaxation condition, resulting in a ceiling effect that masked further enhancements.\u003c/p\u003e \u003cp\u003eLimitations in the Interpretation of the Results\u003c/p\u003e \u003cp\u003eThe finding that the SCL and DST\u0026mdash;both considered indices of the SNS activity\u0026mdash;did not respond uniformly to the sound conditions should be further investigated. One plausible explanation lies in the distinct response characteristics of the SC and ST. As noted in a previous study, the SCL, derived from the SC, reflects the tonic component and is highly sensitive to transient sweating responses triggered by psychological stress, thereby serving as a rapid indicator of increased SNS activity [18]. In contrast, the sympathetic vasoconstrictor nerve activity, which plays a key role in ST regulation, maintains a steady level of vascular tone at rest [24]. When SNS activity is suppressed, these nerves induce near-maximal vasodilation, making ST particularly sensitive to reductions in the SNS activity. These differences in response mechanisms may account for the finding that SNS activation during the N-back task condition was more sensitively captured by SCL. Meanwhile, SNS suppression during the relaxation condition was more clearly reflected by ST changes.\u003c/p\u003e \u003cp\u003eThis study primarily aimed to investigate the effects of inaudible HFC by comparing the FRS and HCS conditions. However, under the N-back task condition, both HF (a PNS index) and SCL (an SNS index) were significantly higher in the NS condition than in the HCS condition. Under the relaxation condition, the DST was significantly higher in the NS condition than in the HCS condition. Further, there were no significant differences between the FRS and NS conditions in any of these comparisons. These findings suggest that the differences observed between the FRS and HCS conditions may not be solely attributable to the presence of inaudible HFC in the FRS condition. Rather, they raise the possibility that the HCS condition\u0026mdash;characterized by the presentation of only audible-range components\u0026mdash;may suppress the ANS regulatory function.\u003c/p\u003e \u003cp\u003eThis finding is supported by previous studies that investigated the impact of HFC on brain activity, which similarly reported that the presentation of only audible-range sound (HCS condition) leads to reductions in alpha-band electroencephalogram power and decreased regional cerebral blood flow in the brainstem and thalamus compared with both the FRS and NS conditions [3,4]. The biological mechanisms underlying these effects remain unclear. However, we have previously reported that natural acoustic environments, such as tropical rainforests, are characterized by a rich presence of inaudible HFC, whereas modern urban environments significantly lack such features [25]. Further, the HCS condition, in which HFC were removed from the original sound source, is acoustically comparable to the audio quality of CDs and digital broadcasts, both of which are now widespread in modern urban environments as a part of conventional digital media. Considering these observations, it is essential to cautiously monitor and further investigate the potential physiological effects associated with inaudible HFC deficiency in contemporary acoustic environments.\u003c/p\u003e \u003cp\u003eAppropriateness of the Task Conditions and Age Group Classification\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the task condition had a significant main effect across all measured indices. In particular, the HF, an index of PNS activity, was significantly lower during the N-back task condition than during the relaxation condition. Conversely, the SNS indices exhibited opposing patterns. Specifically, the SCL was significantly higher during the N-back task condition, and the DST was significantly lower. A higher HF value indicates a greater PNS activity. Meanwhile, elevated SCL and reduced DST values reflect an enhanced SNS activity. These results indicate that the N-back task induced a physiological state characterized by SNS dominance. Meanwhile, the relaxation condition elicited a PNS-dominant state, thereby showing that the two task conditions successfully elicited distinct patterns of the ANS activity.\u003c/p\u003e \u003cp\u003eRegarding age-related differences, the HF and DST exhibited significant main effects in the age groups, with both indices significantly lower in the older group than in the younger group (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). This pattern indicates that older participants had a reduced PNS activity and an increased SNS activity relative to their younger counterparts. These findings are consistent with previous evidence showing that aging is associated with diminished parasympathetic cardiovascular regulation, increased sympathetic tone, and an overall decline in ANS regulatory capacity [21]. Thus, the age group classifications and physiological indices used in the current study may be appropriate and effective for capturing age-related differences in the ANS function.\u003c/p\u003e \u003cp\u003eIn contrast, the SCL, which is another SNS-related index, did not exhibit a significant main effect in the age groups. Although both DST and SCL are indicators of the SNS activity, they are mediated via distinct neurophysiological pathways. Typically, postganglionic sympathetic neurons release norepinephrine, which acts on the target organs [26]. The sympathetic vasoconstrictor nerves regulating cutaneous blood flow\u0026mdash;reflected by the DST\u0026mdash;are primarily adrenergic, thereby releasing norepinephrine [26]. In contrast, the sympathetic innervation of the sweat glands, which contributes to SCL, is mediated by cholinergic neurons that release acetylcholine [26]. These neurochemical differences may account for the divergent age-related patterns observed between the two SNS indices.\u003c/p\u003e \u003cp\u003eFuture Directions\u003c/p\u003e \u003cp\u003eThe current study showed the effects of hypersonic sound on ANS regulation. This finding can provide important insights into the mechanisms underlying the hypersonic effect previously reported in the literature. The activation of brain regions such as the brainstem and hypothalamus regulates a broad range of physiological systems via the ANS, including the visceral organs, body surface, and vascular system. In this context, our results suggest that hypersonic sound may be a foundation for future medical applications aiming to treat and prevent disorders associated with ANS dysregulation or dysfunction. Future research should investigate the clinical potential of hypersonic sound in different conditions, such as lifestyle-related and stress-induced disorders, which are characterized by impaired ANS regulation.\u003c/p\u003e \u003cp\u003eThis research direction is in accordance with the emerging field of information medicine, which seeks to optimize environmental information input to regulate brain function [2,27]. Considering that the brain operates not only as a chemically driven organ but also as an information-processing system responsive to both internal and external stimuli, disruptions in the environmental information flow may impair neural processing and contribute to the development and progression of various psychiatric and neurological disorders. Information medicine represents a complementary approach to traditional pharmacological and surgical interventions, focusing on the information-processing aspects of brain function.\u003c/p\u003e \u003cp\u003eBy elucidating how environmental information influences neural activity, this field aims to develop nonpharmacological strategies for the treatment and prevention of psychiatric and neurological conditions. As discussed in the previous text, natural environments such as tropical rainforests\u0026mdash;where human genetic and neural systems are believed to have evolved\u0026mdash;are characterized by an abundance of inaudible HFC. If human evolution shaped the genetic and neural architectures to process such environmental information and enhance survival under these conditions, then an acoustic environment rich in inaudible HFC may represent an optimal state for the brain\u0026rsquo;s information-processing mechanisms. In contrast, the modern urban soundscape, which is significantly devoid of these HFC, may constitute a significant deviation from this evolutionary ideal. In light of the findings related to the hypersonic effect, advancing the development of information medicine approaches that aim to supplement contemporary urban environments with hypersonic sound is essential [2,27,28].\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis study was supported in part by JSPS KAKENHI Grant Number 19H01093 and 25K03075 for M.H., 23K11370 for E.N., and JST Moonshot R\u0026amp;D Grant Number JPMJMS2296 for M.H.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eK.J., N.K., and M.H. conceived and designed the experiment. N.K. and E.N. created the sound sources. K.J. acquired the data. K.J., N.K., and M.H. analyzed the data. K.J. and M.H. wrote the paper. All authors revised the paper.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe want to thank all of the participants of this study. We express our deepest gratitude to the late Dr. Osamu Ueno of the National Center of Neurology and Psychiatry for his invaluable contribution to this work. We also want to acknowledge Mr. Yusei Watanabe, Ms. Yuria Miyano, Ms. Kosa Fujimori, and Dr. Yuichi Yamashita of the National Center of Neurology and Psychiatry for providing technical support. The authors would like to thank Enago (www.enago.jp) for the English language review.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated in this study will be provided upon reasonable request to the corresponding authors.\u003c/p\u003e"},{"header":"References","content":"\u003cp\u003e1\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Chrousos, G. P. Stress and disorders of the stress system. \u003cem\u003eNat Rev Endocrinol\u003c/em\u003e. \u003cstrong\u003e5\u003c/strong\u003e, 374-381 (2009).\u003c/p\u003e\n\u003cp\u003e2\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Oohashi, T. \u003cem\u003eHypersonic Effect\u003c/em\u003e. (Iwanami Shoten, 2017) (in Japanese).\u003c/p\u003e\n\u003cp\u003e3\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Oohashi, T.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Inaudible high-frequency sounds affect brain activity: hypersonic effect. \u003cem\u003eJ Neurophysiol\u003c/em\u003e. \u003cstrong\u003e83\u003c/strong\u003e, 3548-3558 (2000).\u003c/p\u003e\n\u003cp\u003e4\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Oohashi, T., Nishina, E. \u0026amp; Honda, M. Multidisciplinary study on the hypersonic effect in \u003cem\u003eInter-Areal Coupling of Human Brain Function\u003c/em\u003e (ed. Shibasaki H. \u003cem\u003eet al.\u003c/em\u003e) \u0026nbsp;27-42 (Elsevier, 2002).\u003c/p\u003e\n\u003cp\u003e5\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Kawai, N.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Positive effect of inaudible high-frequency components of sounds on glucose tolerance: a quasi-experimental crossover study. \u003cem\u003eSci Rep\u003c/em\u003e. \u003cstrong\u003e12\u003c/strong\u003e, 1-9 (2022).\u003c/p\u003e\n\u003cp\u003e6\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Fukushima, A.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Frequencies of inaudible high-frequency sounds differentially affect brain activity: Positive and negative hypersonic effects. \u003cem\u003ePLoS One\u003c/em\u003e. \u003cstrong\u003e9\u003c/strong\u003e (2014).\u003c/p\u003e\n\u003cp\u003e7\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Oohashi, T.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e The role of biological system other than auditory air-conduction in the emergence of the hypersonic effect. \u003cem\u003eBrain Res\u003c/em\u003e. \u003cstrong\u003e1073-1074\u003c/strong\u003e, 339-347 (2006).\u003c/p\u003e\n\u003cp\u003e8\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Oohashi, T., Nishina, E., Kawai, N., Fuwamoto, Y. \u0026amp; Imai, H. High-frequency sound above the audible range affects brain electric activity and sound perception. \u003cem\u003eJ Audio Eng Soc\u003c/em\u003e. \u003cstrong\u003e3207\u003c/strong\u003e, 1-25 (1991).\u003c/p\u003e\n\u003cp\u003e9\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Honda, M.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Functional neuronal network subserving the hypersonic effect in \u003cem\u003eICA 2004.\u003c/em\u003e (ed. International Commission for Acoustics) 1751-1754 (2004).\u003c/p\u003e\n\u003cp\u003e10\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Yagi, R., Nishina, E. \u0026amp; Oohashi, T. A method for behavioral evaluation of the \u0026ldquo;hypersonic effect\u0026rdquo;. \u003cem\u003eAcoust Sci Technol\u003c/em\u003e. \u003cstrong\u003e24\u003c/strong\u003e, 197-200 (2003).\u003c/p\u003e\n\u003cp\u003e11\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Yagi, R., Nishina, E., Honda, M. \u0026amp; Oohashi, T. Modulatory effect of inaudible high-frequency sounds on human acoustic perception. \u003cem\u003eNeurosci Lett\u003c/em\u003e. \u003cstrong\u003e351\u003c/strong\u003e, 191-195 (2003).\u003c/p\u003e\n\u003cp\u003e12\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Brunner, E. J.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Social inequality in coronary risk: Central obesity and the metabolic syndrome. Evidence from the Whitehall II study. \u003cem\u003eDiabetologia\u003c/em\u003e. \u003cstrong\u003e40\u003c/strong\u003e, 1341-1349 (1997).\u003c/p\u003e\n\u003cp\u003e13\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Suzuki, K. \u0026amp; Kawakatsu, M. The effect of exposing the inaudible ultrasonic components of the music during a recess on cognitive task in \u003cem\u003eAcoustical Society of Japan.\u003c/em\u003e\u0026nbsp; 1253-1254 (2012) (in Japanese).\u003c/p\u003e\n\u003cp\u003e14\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Vincent, A., Craik, F. \u0026amp; Furedy, J. Relations among memory performance, mental workload and cardiovascular responses. \u003cem\u003eInt J Psychophysiol\u003c/em\u003e. \u003cstrong\u003e23\u003c/strong\u003e, 181-198 (1996).\u003c/p\u003e\n\u003cp\u003e15\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Jaeggi, S., Buschkuehl, M., Perrig, W. \u0026amp; Meier, B. The concurrent validity of the N-back task as a working memory measure. \u003cem\u003eMemory\u003c/em\u003e. \u003cstrong\u003e18\u003c/strong\u003e, 394-412 (2010).\u003c/p\u003e\n\u003cp\u003e16\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Camm, A. J.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. \u003cem\u003eCirculation\u003c/em\u003e. \u003cstrong\u003e93\u003c/strong\u003e, 1043-1065 (1996).\u003c/p\u003e\n\u003cp\u003e17\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Shaffer, F. \u0026amp; Ginsberg, J. P. An overview of heart rate variability metrics and norms. \u003cem\u003eFront Public Health\u003c/em\u003e. \u003cstrong\u003e5\u003c/strong\u003e (2017).\u003c/p\u003e\n\u003cp\u003e18\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Leiner, D. J., Fahr, A. \u0026amp; Fr\u0026uuml;h, H. EDA positive change: A simple algorithm for electrodermal activity to measure general audience arousal during media exposure. \u003cem\u003eComm Methods Meas\u003c/em\u003e. \u003cstrong\u003e6\u003c/strong\u003e, 237-250 (2012).\u003c/p\u003e\n\u003cp\u003e19\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Yamakoshi, T., Kenta, M., Kobayashi, H., Gotoh, Y. \u0026amp; Hirose, H. Feasibility Study on Assessment of Driver\u0026apos;s Stress from Differential Skin Temperature Measurement under Simulated Monotonous Driving. \u003cem\u003eTrans Jpn Soc Med Biol Eng\u003c/em\u003e. \u003cstrong\u003e48\u003c/strong\u003e, 163-174 (2010) (in Japanese).\u003c/p\u003e\n\u003cp\u003e20\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Kanda, Y. Investigation of the freely available easy-to-use software \u0026apos;EZR\u0026apos; for medical statistics. \u003cem\u003eBone Marrow Transplant\u003c/em\u003e. \u003cstrong\u003e48\u003c/strong\u003e, 452-458 (2013).\u003c/p\u003e\n\u003cp\u003e21\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Umetani, K., Singer, D., McCraty, R. \u0026amp; Atkinson, M. Twenty-four hour time domain heart rate variability and heart rate: relations to age and gender over nine decades. \u003cem\u003eJ Am Coll Cardiol\u003c/em\u003e. \u003cstrong\u003e31\u003c/strong\u003e, 593-601 (1998).\u003c/p\u003e\n\u003cp\u003e22\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Hansen, A., Johnsen, B. \u0026amp; Thayer, J. Vagal influence on working memory and attention. \u003cem\u003eInt J Psychophysiol\u003c/em\u003e. \u003cstrong\u003e48\u003c/strong\u003e, 263-274 (2003).\u003c/p\u003e\n\u003cp\u003e23\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Christensen, J.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Diverse autonomic nervous system stress response patterns in childhood sensory modulation. \u003cem\u003eFront Integr Neurosci\u003c/em\u003e. \u003cstrong\u003e14\u003c/strong\u003e (2020).\u003c/p\u003e\n\u003cp\u003e24\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Korthuis, R. J. \u003cem\u003eSkeletal Muscle Circulation\u003c/em\u003e. \u0026nbsp; (Morgan \u0026amp; Claypool Life Sciences, 2011).\u003c/p\u003e\n\u003cp\u003e25\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Nishina, E. \u0026amp; Oohashi, T. Study on the improvement of urban sound environment by the sound with in-audible high frequency components. \u003cem\u003eJ City Plann Inst Jpn\u003c/em\u003e. \u003cstrong\u003e42\u003c/strong\u003e, 139-144 (2007) (in Japanese).\u003c/p\u003e\n\u003cp\u003e26\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;McCorry, L. K. Physiology of the Autonomic Nervous System. \u003cem\u003eAm J Pharm Educ\u003c/em\u003e. \u003cstrong\u003e71\u003c/strong\u003e (2007).\u003c/p\u003e\n\u003cp\u003e27\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Honda, M. Information environment and brain function: A new concept of the environment for the brain in \u003cem\u003eNeurodegenerative Disorders as Systemic Diseases\u003c/em\u003e (ed. Wada K) \u0026nbsp;279-294 (Springer, 2015).\u003c/p\u003e\n\u003cp\u003e28\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Honda, M.\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e Non-pharmacological therapy for behavior and psychological symptoms of dementia (BPSD) utilizing the hypersonic effect: A pilot study. \u003cem\u003eJ Neurol Sci\u003c/em\u003e. \u003cstrong\u003e381\u003c/strong\u003e, 661-662 (2017).\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"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":"autonomic nervous system, homeostasis, hypersonic effect, inaudible high-frequency sounds","lastPublishedDoi":"10.21203/rs.3.rs-6670151/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6670151/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe dysregulation of the autonomic nervous system (ANS) activity notably contributes to the onset and progression of numerous diseases, including lifestyle-related and psychiatric disorders. This necessitates the development of effective nonpharmacological methods for regulating ANS function for therapeutic purposes and disease prevention. This study examined how the presence or absence of the inaudible high-frequency component (HFC) of sounds\u0026mdash;which activates deep-brain structures\u0026mdash;affects the ANS regulatory function. Under the N-back task condition, which requires concentration, exposure to sounds with HFC resulted in significantly higher sympathetic and parasympathetic nervous activities compared to sounds without HFC. Conversely, under the relaxation condition, the sounds with HFC significantly suppressed sympathetic nervous activity relative to sounds without HFC. Therefore, unlike pharmacological agents, which typically exert unidirectional effects on the ANS activity, sounds with HFC may flexibly adjust the sympathetic and parasympathetic nervous activities in response to situational demands.\u003c/p\u003e","manuscriptTitle":"Enhancing the regulatory function of the autonomic nervous system using sounds with inaudible high-frequency components","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-27 13:40:07","doi":"10.21203/rs.3.rs-6670151/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-06-06T12:28:07+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-05T16:43:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-03T09:20:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"242233589021077076161052865230045287187","date":"2025-05-27T23:12:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"232788858349681128035307859276564685054","date":"2025-05-27T22:40:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"311684545375762967129493843427103198768","date":"2025-05-27T19:37:55+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-05-27T18:59:53+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-05-27T18:48:22+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-21T05:22:59+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-20T13:44:20+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-05-15T07:43:24+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":"39dc0b56-9af0-4bda-bf9d-78f4fadbc581","owner":[],"postedDate":"May 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":48842688,"name":"Biological sciences/Neuroscience/Peripheral nervous system/Autonomic nervous system"},{"id":48842689,"name":"Health sciences/Health care"}],"tags":[],"updatedAt":"2025-07-28T14:30:55+00:00","versionOfRecord":{"articleIdentity":"rs-6670151","link":"https://doi.org/10.1038/s41598-025-11190-9","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-07-23 00:00:00","publishedOnDateReadable":"July 23rd, 2025"},"versionCreatedAt":"2025-05-27 13:40:07","video":"","vorDoi":"10.1038/s41598-025-11190-9","vorDoiUrl":"https://doi.org/10.1038/s41598-025-11190-9","workflowStages":[]},"version":"v1","identity":"rs-6670151","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6670151","identity":"rs-6670151","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}