Lateralized readiness potentials reveal motor slowing in the aging brain

Area of Science:

• Neuroscience
• Cognitive Aging
• Human Motor Control

Background:

• Older adults exhibit slower reaction times (RTs) compared to younger individuals, particularly in response to motion onset.
• The underlying causes of this age-related slowing are debated, with hypotheses including cognitive slowing and motor slowing.

Purpose of the Study:

• To investigate the specific origins of slowed reaction times to motion onset in older adults.
• To differentiate between perceptual/decision-making processes and motor programming/execution as causes of age-related slowing.

Main Methods:

• Utilized electroencephalogram (EEG) to measure the lateralized readiness potential (LRP).
• Participants identified the direction of motion (up/down) after its onset, with RTs recorded.
• LRP analysis was employed to distinguish between perceptual and motor contributions to RT differences.

Main Results:

• Older participants demonstrated significantly slower RTs compared to younger participants.
• LRP data indicated that the majority of the slowed response in older adults stemmed from motor processes.
• Perceptual processing did not appear to be the primary cause of the observed RT delays.

Conclusions:

• The slowed reaction times in older adults responding to motion onset are predominantly attributable to motor slowing.
• Findings suggest age-related changes in motor programming and execution contribute more significantly than perceptual deficits.
• The study provides insights into motion processing and neural inhibition in the aging brain.