Date of Award

May 2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Health Sciences

First Advisor

Jinsung Wang

Committee Members

Adam Greenberg, Stephen Cobb, Inga Wang, Kevin Keenan

Keywords

Motor adaptation, motor learning, motor memory interference, Motor memory retention, savings

Abstract

Visuomotor adaptation is fundamental to everyday activities, from the simple act of reaching for a cup to complex athletic maneuvers. The concept of savings is particularly interesting as it sheds light on how motor skills are acquired, retained, and relearned over time. Savings refers to the phenomenon where motor skills that have been previously learned are reacquired or relearned more rapidly after a period of inactivity or after the individual has undergone de-adaptation. While it was initially believed that savings in motor adaptation stemmed from implicit learning mechanisms, recent research indicates that it is primarily attributed to explicit recall of strategies. However, various factors such as providing information about the perturbation, asking subjects to provide a verbal aiming report, offering specific strategies to counteract the perturbation, and manipulating the nature of perturbation introduction during visuomotor adaptation can impact the explicit components of motor adaptation. The primary goal of this dissertation is to determine the potential benefits of training protocols that vary in the involvement of explicit and implicit learning components on short- and long-term savings following visuomotor adaptation. In addition, we aimed to investigate whether competing memories developed through opposing visuomotor perturbations consolidate differently with varying degree of explicit and implicit components. Our results from Experiment 1 and 2 suggested that introducing different levels of implicit and explicit learning components during adaptation to a 24-degree visuomotor rotation has a varied impact on immediate savings (five minutes) between the gradual-perturbation group (most implicit) and the three abrupt-perturbation groups (less implicit, more explicit, and most explicit). Moreover, incorporating varying degrees of explicitness or implicitness during learning to counteract visuomotor rotation did not lead to improved long-term savings measured at one week and one month post initial learning. In Experiment 3, we showed that consolidation of motor memories associated with visuomotor adaptation is affected by the training methods that involves varying degrees of interference rather than by those that differ in the utilization of implicit or explicit components. We anticipate that findings from this dissertation will be valuable for therapists in tailoring and personalizing rehabilitation sessions to reduce interference and improve long-term retention of motor memories.

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