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Abstract

 
Abstract No.:B-D2131
Country:Canada
  
Title:LEARNING IS SIMILAR WHETHER SPREAD ACROSS WEEKLY SESSIONS OR DURING A SINGLE SESSION FOR BOTH VISUAL AND FORCE PERTURBATIONS
  
Authors/Affiliations:1 Milad Modabber*; 1 Jason Neva; 1 Denise Henriques;
1 School of Kinesiology and Health Science & Centre for Vision Research York University, Toronto, ON, Canada

  
Content:Objective: Numerous studies have demonstrated that the brain learns to adjust reaching movements in order to correct for altered visual feedback and force perturbations on the hand. These studies usually involve subjects reaching under these perturbed conditions for many trials in a single session so that reaching trajectories usually return to pre-perturbation performance. However, it is not yet clearly understood how well the brain can learn these adjustments when there are gaps of time between learning sessions. Here, we investigate whether subjects can learn just as well when adapting to these perturbations across multiple short training sessions compared to a single session.


Materials & Methods: In two experiments, we had subjects reach to visual targets when exposed to either altered visual feedback of their hand or a perturbation of their hand. These subjects were exposed to these perturbations across five weekly sessions of 20 trials and during a single session of 100 trials. In the visuomotor adaptation task, participants reached to visual targets by moving a cursor, representing their hand, onto targets. During training, the motion of the cursor was rotated by 30o clockwise (CW) or counter-clock wise (CCW) relative to the hand trajectory. In the dynamic adaptation task, another group of participants reached while gripping the handle of a robot manipulandum. During training, the robot exerted a velocity-dependant force perturbation, in either CCW or CW orthogonal directions, while reaching.


Results: Results from both studies show that the learning rates for the weekly session were similar to those in the single session for the visual and force perturbations. Interestingly, the gaps between the weekly sessions did not lead to any loss of previous learning.

Conclusion: This suggests that the brain does not need continuous reaching practice in order to form a new internal model of arm kinematics and dynamics. Rather it can adapt to the new visuomotor mapping or force perturbation and retain it throughout the 7-day span between each of the weekly reaching sessions.

  
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