Age-related changes in short-latency motor cortex inhibition

Area of Science:

• Neuroscience
• Motor Control
• Human Aging

Background:

• Aging is associated with motor changes, but the underlying neural mechanisms are not fully understood.
• Intracortical inhibition and facilitation are crucial for precise motor control.
• Previous research has yielded conflicting results regarding age-related changes in these processes.

Purpose of the Study:

• To investigate whether short-latency intracortical inhibition (SICI) and intracortical facilitation (ICF) are altered in older men.
• To determine if age-related changes in corticospinal excitability influence SICI and ICF.
• To examine hemispheric differences in SICI and ICF with aging.

Main Methods:

• Paired-pulse transcranial magnetic stimulation (TMS) was used to assess SICI and ICF.
• Participants included 17 older men (mean age 63.1 years) and 13 younger men (mean age 20.0 years).
• Motor-evoked potentials were recorded from the first dorsal interosseous muscle at rest, with varying interstimulus intervals.

Main Results:

• SICI was generally greater in the left hemisphere compared to the right, irrespective of age.
• A potential age-related increase in SICI was observed at specific intervals, but this disappeared when accounting for differences in active motor threshold (aMT).
• ICF remained unaltered across age groups, and corticospinal stimulus-response curves were not significantly affected by aging.

Conclusions:

• SICI and ICF, when measured at rest in men, do not appear to be significantly altered by aging.
• Age-related changes in active motor threshold do not fully explain the observed (but not significant) differences in SICI.
• Further research is needed to explore age-related changes in SICI/ICF during motor tasks.