Association between neural-drive variability and motor function in middle-aged and older adults

Area of Science:

• Neuroscience
• Motor Control
• Gerontology

Background:

• Aging is associated with declines in motor function.
• Understanding the neural underpinnings of motor variability in older adults is crucial for developing targeted interventions.
• The NIH Toolbox provides standardized measures of motor function.

Purpose of the Study:

• To review the extent to which neural drive variability explains motor function performance in middle-aged and older adults.
• To explore the spinal mechanisms contributing to neural drive variability.
• To assess the relationship between neural drive variability and performance on NIH Toolbox motor tasks.

Main Methods:

• Review of existing literature on neural drive and motor function.
• Examination of spinal mechanisms including synaptic input oscillations and synaptic noise.
• Analysis of the coefficient of variation for force during submaximal contractions as a proxy for neural drive variability.
• Correlation of neural drive variability with performance on balance, dexterity, endurance, locomotion, and handgrip strength tasks.

Main Results:

• Neural drive variability explains moderate variance in balance, dexterity, and endurance performance.
• Locomotion performance is linked to motor-unit discharge characteristics in calf muscles.
• Handgrip strength is associated with motor-unit timing across forearm-hand muscles.
• Submaximal isometric contractions can reveal neural drive variability relevant to dynamic motor tasks.

Conclusions:

• Neural drive variability is a significant factor contributing to motor function variance in older adults.
• Specific aspects of neural drive variability relate to different motor tasks.
• Further research is needed to broaden the scope of tasks used to measure neural drive variability for enhanced explanatory power.