Abstract
Age-related neurodegenerative and neurochemical changes are considered to be the basis for the decline of motor function; however, the change of effective connections in cortical motor networks that come with aging remains unclear. Here, we investigated the age-related changes of the dynamic interaction between cortical motor regions. Twenty young subjects and 20 older subjects underwent both right hand motor execution (ME) and right hand motor imagery (MI) tasks by using functional magnetic resonance imaging. Conditional Granger causality analysis (CGCA) was used to compare young and older adults’ effective connectivity among regions of the motor network during the tasks. The more effective connections among motor regions in older adults were found during ME; however, effective within-domain hemisphere connections were reduced, and the blood oxygenation level dependent (BOLD) signal was significantly delayed in older adults during MI. Supplementary motor area (SMA) had a significantly higher In+Out degree within the network during ME and MI in older adults. Our results revealed a dynamic interaction within the motor network altered with aging during ME and MI, which suggested that the interaction with cortical motor neurons caused by the mental task was more difficult with aging. The age-related effects on the motor cortical network provide a new insight into our understanding of neurodegeneration in older individuals.
Highlights
Age-related neurodegenerative and neurochemical changes have been believed to impair motor performance and cognitive functions
The present results showed that interaction within the motor network was changed with aging during task performance
The increased between-hemisphere connectivity in the older group during motor execution (ME) may be related to a compensatory mechanism, in that the older adults need greater between-hemisphere interactions to protect against age-related decreases in ME
Summary
Age-related neurodegenerative and neurochemical changes have been believed to impair motor performance and cognitive functions. Many fMRI studies have investigated motor functional changes with aging. There is a greater extent of activation in the ipsilateral motor cortex during unimanual movement in older subjects compared to younger subjects (Carp et al, 2011). Most of these results are explained as a compensatory mechanism in the. Many studies focus on how to delay the agerelated decrease in motor performance, and some researchers have suggested that mental training through motor imagery (MI) may be beneficial to improving motor function (Jeannerod and Decety, 1995; Jeannerod, 2001)
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