Abstract
Task performance for behaviors that engage motor cognitive processes may be particularly sensitive to age-related changes. One well-studied model of cognitive motor function involves engagement of action selection (AS) processes. In young adults, task conditions that add AS demands result in increased preparation times and greater engagement of bilateral dorsal premotor (PMd) and parietal cortices. The current study investigated the behavioral and neural response to a change in motor cognitive demands in older adults through the addition of AS to a movement task. Sixteen older adults made a joystick movement under two conditions during functional magnetic resonance imaging. In the AS condition, participants moved right or left based on an abstract rule; in the execution only (EO) condition, participants moved in the same direction on every trial. Across participants, the AS condition, as compared to the EO condition, was associated with longer reaction time and increased activation of left inferior parietal lobule. Variability in behavioral response to the AS task between participants related to differences in brain function and structure. Overall, individuals with poorer AS task performance showed greater activation in left PMd and dorsolateral prefrontal cortex and decreased structural integrity of white matter tracts that connect sensorimotor, frontal, and parietal regions—key regions for AS task performance. Additionally, two distinct patterns of functional connectivity were found. Participants with a pattern of decreased primary motor–PMd connectivity in response to the AS condition, compared to those with a pattern of increased connectivity, were older and had poorer behavioral performance. These neural changes in response to increased motor cognitive demands may be a marker for age-related changes in the motor system and have an impact on the learning of novel, complex motor skills in older adults.
Highlights
The performance of skilled motor actions declines with age, which has direct implications for the performance of everyday functional activities (Seidler et al, 2010)
We hypothesized that individuals would show a significant increase in planning time that corresponded to an increase in bilateral PMd and parietal cortex activation for action selection (AS) compared to simple movement execution, similar to previous research in young adults (Grafton et al, 1998a; Grol et al, 2006; O'Shea et al, 2007a; Toni et al, 2002)
The increase in motor preparation time to perform the AS task over simple movement execution (EO) corresponded to increased activation in the inferior parietal lobule, similar to previous reports in young adults (Grafton et al, 1998a; Grol et al, 2006; O'Shea et al, 2007a; Toni et al, 2002) and further supporting the role this region plays in visuomotor actions (Fogassi and Luppino, 2005; Grefkes and Fink, 2005)
Summary
The performance of skilled motor actions declines with age, which has direct implications for the performance of everyday functional activities (Seidler et al, 2010). Older adults tend to move slower than younger adults with decreased coordination and less smoothness (Cooke et al, 1989; Ketcham et al, 2002; Poston et al, 2009; Seidler et al, 2002) This decline in motor skill performance with age corresponds to changes in the peripheral and central neural structures that support movement (Seidler et al, 2010; Ward, 2006). The neural correlates of AS and the role of PMd for AS in older adults have not been reported
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
