Investigation of neurobiological responses to Theta Burst Stimulation during recovery from mild traumatic brain injury (mTBI)

The ability of the brain to recover following neurological insult is of considerable interest in mild traumatic brain injury (mTBI) populations. To date, a limited amount of research has examined changes in brain function over time following mTBI. Investigating whether non-invasive brain stimulation (NIBS) can modulate neurophysiology and cognitive performance is particularly relevant for therapeutic targeting post injury. The purpose of the current study was to investigate the neurobiological effects of a single session of intermittent theta burst stimulation (iTBS) applied to the dorsolateral prefrontal cortex (DLPFC) in participants with mTBI during recovery. Changes to neurophysiology were assessed with electroencephalography (EEG) and transcranial magnetic stimulation combined with EEG (TMS-EEG). Digit span working memory accuracy was assessed as a marker of cognitive performance. 30 patients in the subacute phase following mTBI (within one month post-injury) and 26 demographically matched controls were assessed. Participants also completed 3-month (mTBI: N = 21, control: N = 26) and 6-month (mTBI: N = 15, control: N = 24) follow up sessions. Cluster-based analyses demonstrated iTBS did not reliably modulate neurophysiological activity, and no differences were found in cognitive performance in either mTBI or control group participants across any of the assessment time points. The factors that may have contributed to our results are unclear, and possible limitations to our experimental design are discussed. Our findings highlight additional research is required to establish the effects of iTBS on plasticity and cognition in a mTBI population prior to therapeutic application.