Mild traumatic brain injury alters function in the dorsolateral prefrontal cortex: a TMS-EEG study

Area of Science:

• Neuroscience
• Neurophysiology
• Brain Injury Research

Background:

• Mild traumatic brain injury (mTBI) effects on cognitive brain areas are not fully understood.
• Investigating neurophysiological changes in the dorsolateral prefrontal cortex (DLPFC) is crucial for understanding mTBI's impact.

Purpose of the Study:

• To investigate the neurophysiological effects of mTBI on the DLPFC using transcranial magnetic stimulation combined with electroencephalography (TMS-EEG).
• To assess cortical inhibition and neuroplasticity in mTBI patients compared to controls.

Main Methods:

• TMS-EEG was employed to measure cortical inhibition (paired-pulse TMS) and long-term depression (LTD)-like plasticity (continuous theta burst stimulation [cTBS]) in the DLPFC.
• Responses were analyzed in both temporal (TMS-evoked potentials; TEPs) and spectral (TMS-related oscillations; TROs) domains.
• Cognitive function was assessed using the N-back and Trail Making Test (TMT).

Main Results:

• mTBI was associated with reduced measures of inhibition and plasticity in TEPs.
• TRO data indicated an increased response to stimulation in mTBI patients, specifically in high-frequency bands.
• While TMT performance was impaired in mTBI patients, it did not correlate with the observed neurophysiological changes.

Conclusions:

• DLPFC function is altered post-mTBI, with the observed effects varying based on whether evoked (TEPs) or induced (TROs) activity is analyzed.
• These findings suggest potential dysregulation of cortical inhibitory function and neuroplasticity in the DLPFC following mTBI.