Acute and longitudinal changes in motor cortex function following mild traumatic brain injury

Area of Science:

• Neuroscience
• Traumatic Brain Injury Research
• Motor Cortex Function

Background:

• Mild traumatic brain injury (mTBI) is a common neurological condition.
• Understanding the long-term effects of mTBI on brain function is crucial for effective rehabilitation.
• Cortical excitability and inhibition are key aspects of motor control and can be altered by brain injury.

Purpose of the Study:

• To investigate the acute and longitudinal changes in motor cortex excitability and inhibition following mTBI.
• To compare these changes in individuals with mTBI to healthy control participants.
• To determine the recovery trajectory of these neural parameters over two months.

Main Methods:

• A longitudinal paired case-control study design was employed.
• 15 adults with mTBI and 15 matched controls were assessed.
• Transcranial magnetic stimulation (TMS) was used to measure resting motor threshold (RMT), motor evoked potential peak-to-peak amplitude (MEPamp), and cortical silent period (CSP) duration at multiple time points post-injury.

Main Results:

• No significant differences in cortical excitability (RMT and MEPamp) were observed between the mTBI and control groups at any time point.
• Individuals with mTBI exhibited a significantly longer cortical silent period (CSP) compared to controls, indicating increased intra-cortical inhibition.
• This heightened intra-cortical inhibition was present acutely (72 hours post-injury) and persisted throughout the 2-month recovery period.

Conclusions:

• mTBI has a minimal impact on motor cortex excitability.
• mTBI leads to an acute and sustained increase in intra-cortical inhibition.
• These findings suggest that altered neural inhibition is a key characteristic of motor cortex dysfunction following mTBI.