Abstract
Sequence-specific postural motor learning in a target-directed weight-shifting task in 12 older and 12 young participants was assessed. In the implicit sequence learning condition participants performed a concurrent spatial cognitive task and in the two explicit conditions participants were required to discover the sequence order either with or without the concurrent cognitive task. Participants moved a cursor on the screen from the center location to one of the target locations projected in a semi-circle and back by shifting their center of pressure (CoP) on force plates. During the training the targets appeared in a simple fixed 5-target sequence. Plan-based control (i.e., direction of the CoP displacement in the first part of the target-directed movement) improved by anticipating the sequence order in the implicit condition but not in the explicit dual task condition. Only the young participants were able to use the explicit knowledge of the sequence structure to improve the directional error as indicated by a significant decrease in directional error over practice and an increase in directional error with sequence removal in the explicit single task condition. Time spent in the second part of the movement trajectory to stabilize the cursor on the target location improved over training in both the implicit and explicit sequence learning conditions, for both age groups. These results might indicate that an implicit motor learning method, which holds back explicit awareness of task relevant features, may be desirable for improving plan-based motor control in older adults.
Highlights
Repeating patterns or sequences occur often in our environments, and in many activities of daily living a sequence of individual acts is performed in interaction with the environment
Since postural control becomes less automatic, depending on the complexity of the motor task, the execution of a concurrent cognitive task will lead to performance decrements (Huxhold et al, 2006; Boisgontier et al, 2013)
The experiment was conducted in the Computer Assisted Rehabilitation Environment laboratory (CAREN; Motek Medical)
Summary
Repeating patterns or sequences occur often in our environments, and in many activities of daily living a sequence of individual acts is performed in interaction with the environment. Prediction of, adaptation to, and learning about, environmental regularities on the basis of preceding events may assist in how the body needs to be moved in order to achieve the task goal, and requires adequate postural control (Sturnieks et al, 2008; de Vries et al, 2014). Older adults have greater need for conscious attention to maintain good postural control, due to impaired sensory and motor system functions. Since postural control becomes less automatic, depending on the complexity of the motor task, the execution of a concurrent cognitive task will lead to performance decrements (Huxhold et al, 2006; Boisgontier et al, 2013)
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