GENERALIZATION OF MOTOR AND SENSORY CHANGES IN MOTOR LEARNING
Ahmed Mostafa, Denise Henriques
School of Kinesiology and Health Science, York University, Toronto, ON
It has been proposed that our brain evolves to produce movements. Thus, more research is
required to determine the underlying mechanisms for integrating various sensory inputs to carry
out a movement. We study visuomotor adaptation to have a better understanding of how the
brain functions. Motor adaptation is a type of motor learning that involves remapping the
relationship between sensory information and the motor commands following a perturbation. We
use a robot manipulandum in order to rigorously control hand position and therefore
proprioceptive feedback about hand position, in order to test the role of hand proprioception in
motor learning in a way that few labs can do. Specifically, our paradigms involve subjects
adapting their reaching movements in response to altered visual feedback of their hand, and then
we use the robot to measure whether this adaptation leads to changes in felt hand position, what
we call proprioceptive recalibration. The goal of my proposed studies is to examine the extent by
which these changes in hand proprioception generalize to the opposite hand and across the
workspace. Quantifying these generalization patterns will provide insight on how this
sensorimotor remapping occurs.
Study #1: Intermanual Transfer and Proprioceptive Recalibration Following Training with
Translated Visual Feedback of the Hand. Research Question: Do motor and proprioceptive
changes transfer intermanually following training with altered visual feedback of the hand?
Methods: After reach-training with an aligned and translated cursor, we assessed the resulting
changes in movement (made without the cursor) and felt hand position for both the trained and
untrained hand. To assess felt hand position, subjects moved their hand out along a robotgenerated constrained path to a specified location, at which time a marker appears and they
indicate where they perceived their hand was relative to the marker. Results: Our published
results show that while reach adaptation transferred from the dominant to the non-dominant
hand, proprioceptive recalibration did not transfer. This suggests that this sensory and motor
recalibration may be independent.
Study #2: Generalization of Proprioceptive Recalibration to Different Distances of the
Workspace. Research Question: Do proprioceptive changes generalize to different distances
following visuomotor adaptation? Methods: Again, we will measure both changes in reaches
(without a cursor) and change in hand proprioception to various novel locations after subjects
adapt their reaches with a rotated cursor to two trained target locations. We will compare how
these motor and proprioceptive changes generalize to these novel targets located at different
distances from the trained targets. Results: Motor adaptation generalizes to near-novel and farnovel distances. Generalization for proprioceptive recalibration was significantly smaller at the
far locations. This suggests differences in generalization patterns for sensory and motor changes
following visuomotor rotation-adaptation.