Abstract
Human central nervous system (CNS) undergoes neurological changes during the aging process, leading to declines in hand and finger functions. Previous studies have shown that the CNS can independently process multi-finger force control and moment of force control. However, if both force and moment control are simultaneously imposed by motor task constraints, the CNS needs to resolve competing interests of generating negative and positive covariances between fingers, respectively, which causes “conflict of interest or COI”. Here, we investigated how aging affects the CNS’s abilities to solve COI through a new experimental paradigm. Both elderly and young subjects performed a constant force production task using index and middle fingers under two conditions, multi-finger pressing with no COI and with COI. We found that the elderly increased variance of a virtual finger (VF: an imagined finger producing the same mechanical effect as both fingers together) in time-to-time basis (i.e. online control), while increasing covariance between individual fingers (IF) forces in trial-to-trial basis (i.e. offline control) with COI than no COI. Aging affects the CNS’s abilities to solve COI by deteriorating VF actions in online control and IF actions in offline control.
Highlights
Our hands are one of the most versatile parts of the human body, and we use them to perform a variety of day-to-day activities such as eating, writing, driving, etc
The pair-wise comparisons showed that overall mean-squared error (OMSE) of the elderly group during additional constraint (AC) task was significantly greater than no additional constraint (NC) task (p = 0.001) while OMSE of the young group did not differ between tasks. (Fig 3A)
Our study investigated aging-related changes in the hierarchical organization of multi-finger force control during two-finger pressing tasks, which induced COI problem to the central nervous system (CNS)
Summary
Our hands are one of the most versatile parts of the human body, and we use them to perform a variety of day-to-day activities such as eating, writing, driving, etc. The hands undergo many neurological and biomechanical changes, negatively impacting hand dexterity and consequentially the quality of life in the elderly [1, 2]. Previous studies have shown that aging is associated with the declines in strength [3], muscle mass [4], and finger dexterity [5] as well as degeneration of the central nervous system [6]. The effect of aging on the CNS’s control mechanisms of hand function is still poorly understood, regarding the association between aging and external task constraints that are imposed by motor tasks [7].
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
