Generalization of Visuomotor Adaptation in the Dominant and Non-Dominant Upper Limb
Restricted (Penn State Only)
- Author:
- Mier, Jonathan
- Area of Honors:
- Kinesiology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Robert L Sainburg, Thesis Supervisor
Mark Dyreson, Thesis Honors Advisor - Keywords:
- Reaching
Generalization
Visuomotor Rotation
Motor Learning - Abstract:
- In neurorehabilitation, it is important to study how motor learning that occurs in a clinical setting translates or “generalizes” to improvements in other similarly-related contexts in everyday life. Prior research on generalization of upper limb learning has focused on the transfer of information between arms (interlimb transfer) or within the dominant, right arm (within-arm generalization), thus less is known about generalization in the non-dominant, left arm. Furthermore, research on the timescale in which generalization occurs during the initial period of learning is scarce. To examine this, we asked 10 participants (5 using their right hand, 5 using their left) to make a series of targeted reaching movements in a 2-D virtual environment. After a period of veridical hand-cursor feedback, a visual perturbation was introduced where participants had to learn to counteract a 30 deg counter-clockwise rotation of the cursor relative to their unseen hand position. On random trials throughout this learning process, participant’s reached towards novel target locations without visual feedback to test the generalization of learning. We measured changes in direction error at peak velocity and end position errors under the visual rotation, then measured how these changes differed between generalization and learning trials and between left and right hand groups. We found that the reduction of initial direction error with practice was similar between left and right hand groups. Linear regression models also showed a strong positive relationship between initial direction accuracy in generalization and learning trials in both left and right hand groups. Conversely, reduction in end position errors was increased in generalization trials, particularly during the early learning trials, which we suggest resulted from the absence of visual feedback. The strong proportionality between learning and generalization in this study suggests that small improvements made during neurorehabilitation may generalize to other similarly related tasks before considerable motor impairment recovery is completed.