Clinical symptoms, cognitive performance and cortical activity following mild traumatic brain injury (mTBI)

Objective To investigate clinical symptoms, cognitive performance and cortical activity following mild traumatic brain injury (mTBI). Methods Thirty individuals in the sub-acute phase post mTBI and 28 healthy controls with no history of head injury were compared on clinical, cognitive and cortical activity measures. Measures of cortical activity included; resting state EEG, task related EEG and combined transcranial magnetic stimulation with electroencephalography (TMS-EEG). Primary analyses investigated clinical, cognitive and cortical activity differences between groups. Exploratory analyses investigated the relationships between these measures. Results At 4 weeks’ post injury, mTBI participants exhibited significantly greater post concussive and clinical symptoms compared to controls; as well as reduced cognitive performance on verbal learning and working memory measures. mTBI participants demonstrated alterations in cortical activity while at rest and in response to stimulation with TMS. Conclusions The mTBI group demonstrated neurophysiological markers of altered excitatory and inhibitory processes which impact neural function. Further research is needed to explore the relationship between these pathophysiologies and clinical/cognitive symptoms in mTBI. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial ACTRN12616001038482 ### Funding Statement This work was supported by an Australian Postgraduate Award Scholarship (HLC). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics Committees of both Alfred Health and Monash University gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes We do not have ethical approval to make this data publicly available, as our approval predated our inclusion of such approvals (which we now do routinely).