Age-related Differences in Pre- and Post-synaptic Motor Cortex Inhibition are Task Dependent

Area of Science:

• Neuroscience
• Motor Control
• Aging Research

Background:

• Healthy aging influences post-synaptic motor cortex inhibition, affecting hand muscles.
• Previous research indicates age-related differences in short- (SICI) and long-interval intracortical inhibition (LICI).
• The impact of aging on pre-synaptic interactions of SICI and LICI during motor tasks remains unclear.

Purpose of the Study:

• To investigate age-related differences in pre- and post-synaptic motor cortex inhibition.
• To assess inhibition at rest and during index finger abduction and precision grip tasks.
• To understand how aging affects intracortical inhibitory circuits during motor performance.

Main Methods:

• Utilized transcranial magnetic stimulation (TMS) in young and older adults.
• Measured SICI (2 ms ISI) and LICI (100, 150 ms ISI) using paired-pulse TMS.
• Employed triple-pulse TMS to examine SICI primed by LICI.

Main Results:

• Older adults showed greater SICI during precision grip but not at rest or during abduction.
• Reduced LICI was observed in older adults at rest (150 ms ISI).
• Disinhibition was reduced in older adults at rest and during abduction when SICI was primed by LICI.

Conclusions:

• Age-related differences exist in both pre- and post-synaptic motor cortex inhibition.
• These inhibitory changes may contribute to impaired hand function in older adults.
• Motor task performance reveals specific age-related alterations in cortical inhibition.