Abstract
Simultaneous execution of cognitive and sensorimotor tasks is critical in daily life. Here, we examined whether dexterous manipulation, a highly habitual and seemingly automatic behavior, involves high order cognitive functions. Specifically, we explored the impact of reducing available cognitive resources on the performance of a precision grip-lift task in healthy participants of three age groups (18–30, 30–60 and 60–75 years). Participants performed a motor task in isolation (M), in combination with a low-load cognitive task (M + L), and in combination with a high-load cognitive task (M + H). The motor task consisted in grasping, lifting and holding an apparatus instrumented with force sensors to monitor motor task performance. In the cognitive task, a list of letters was shown briefly before the motor task. After completing the motor task, one letter of the list was shown, and participants reported the following letter of the list. In M + L, letters in the list followed the alphabetical order. In M + H, letters were presented in random order. Performing the high-load task thus required maintaining information in working memory. Temporal and dynamic parameters of grip and lift forces were compared across conditions. During the cognitive tasks, there was a significant alteration of movement initiation and a significant increase of grip force (GF) throughout the grip-lift task. There was no interaction with “age”. Our results demonstrate that planning and the on-line control of dexterous manipulation is not an automatic behavior and, instead, that it interacts with high-level cognitive processes such as those involved in working memory.
Highlights
Dexterous manipulation is probably the most habitual way we interact with objects of the environment
We show that performing a simple motor task such as gripping, lifting and holding an object can be impacted by the concomitant performance of a cognitive task
Several aspects of the grip-lift motor performance were modified during the dual task conditions as compared to the condition during which the motor task was performed alone, especially during the high load working memory condition
Summary
Dexterous manipulation is probably the most habitual way we interact with objects of the environment. Besides their apparent simplicity, rely on complex anticipatory and online controls on the movement (Westling and Johansson, 1984; Nowak and Hermsdörfer, 2004; Witney et al, 2004). The great majority of studies aiming at understanding the neural mechanisms underlying dexterous manipulation have focused on motor tasks performed in isolation. Assessment of motor dysfunction in patients, or assessment of changes in motor function induced, for example, by post-stroke rehabilitation, always rely on the performance of isolated motor tasks. In our daily life, object manipulation is most often performed concomitantly to other tasks, such as manipulating a glass while having a conversation, or interacting with a computer or smartphone.
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