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Explicit Information Interferes with Implicit Motor Learning of Both Continuous and Discrete Movement Tasks After Stroke

Boyd, Lara A PT, PhD1; Winstein, Carolee J PT, PhD, FAPTA2

Journal of Neurologic Physical Therapy: June 2006 - Volume 30 - Issue 2 - p 46–57
doi: 10.1097/01.NPT.0000282566.48050.9b
Research Article

A large portion of the rehabilitation experience after stroke relies on implicit learning. However, our understanding of how best to facilitate motor learning after stroke is limited by a paucity of research that has explored the interaction between explicit information and implicit learning across various task domains. Previously we reported that the delivery of explicit instructions disrupted implicit motor learning after stroke that involved the sensorimotor cortical areas or basal ganglia. The purpose of this study was to determine the robustness of these findings by determining whether they could be replicated with 2 motor tasks, one discrete and one continuous, employed by the same group of participants. Then individuals with stroke in the sensorimotor cortical areas (SMC), 10 with stroke in the basal ganglia (BG), and 10 age-matched healthy controls (HC) participated in this study. Each completed 3 days of practice of both a discrete implicit motor task (the serial reaction time task) and a continuous motor task (the continuous tracking task); all returned on a fourth day for retention tests. By random designation, participants were divided into either the explicit information (EI) or no explicit information (No-EI) groups. Consistent with previous results, we found that the response to explicit information after stroke was uniformly negative regardless of task or lesion location; both stroke groups demonstrated an interference effect of explicit information while the healthy control group did not. Strengthening these findings is the fact that the interference effect of explicit information was not task dependent. This point is particularly important for rehabilitation scientists as they instruct clients during various therapeutic tasks after stroke. Our data suggest that certain forms of explicit information delivered before task practice may not be as useful for learning as discovering the solution to the motor task with practice alone, and this is regardless of the type of task being learned.

1Department of Physical Therapy and Rehabilitation Sciences, University of Kansas Medical Center, Kansas City, KS (lboyd@kumc.edu)

2Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA

© 2006 Neurology Section, APTA