Reduced brain connectivity and mental flexibility in mild traumatic brain injury

OBJECTIVE: A mild traumatic brain injury (mTBI), or concussion, has known neuropsychological sequelae, and neuroimaging shows disturbed brain connectivity during the resting state. We hypothesized that task‐based functional connectivity measures, using magnetoencephalography (MEG), would better link the neurobiological underpinnings of cognitive deficits to specific brain damage. METHODS: We used a mental flexibility task in the MEG and compared brain connectivity between adults with and without mTBI. RESULTS: Affected individuals showed significant reductions in connectivity. When challenged with a more difficult task, these individuals were not able to “boost” their connectivity, and as such, showed deterioration in performance. INTERPRETATION: We discuss these findings in the context of limitations in cognitive reserve as a consequence of a mTBI.