Parallel stages of learning and recovery of skilled reaching after motor cortex stroke: "oppositions" organize normal and compensatory movements.

Full Abstract

Forelimb/hand motor cortex injury in rodents and primates causes impairments in skilled paw/hand movements that includes a period of movement absence followed by functional recovery/compensation. Although the postsurgical period of movement absence has been attributed to "shock" or "diaschisis", the behavior of animals during this period has not been fully described. Here, rats were trained to reach for single food pellets from a shelf and then the vasculature of the forelimb region of the sensorimotor cortex contralateral to the reaching limb was removed. A control group received a posterior parietal cortex devasularization. Frame-by-frame video analysis of reaching behavior showed that the stages of the acquisition of skilled reaching and the stages of recovery after motor cortex stroke were similar. The animals sequentially learn three relationships or "oppositions" between a body part and the food target. The oppositions are invariant relationships but each can be achieved with movements that can vary from reach to reach and between rats. A snout-pellet opposition organizes the movements of orienting, a paw-pellet opposition organizes limb transport and grasping the pellet in the digits, and a mouth-pellet opposition organizes limb withdrawal and the release of the food into the mouth. The three oppositions and the movements that they recruit were disrupted after motor cortex damage, but not parietal cortex damage. The oppositions were reestablished after stroke in the order in which they were acquired prior to stroke. Enduring impairments were more noticeable in transport and withdrawal oppositions. That the stages of recovery from motor cortex stroke parallel those of initial acquisition are discussed in relation to contemporary explanations of diaschisis and the contribution of motor cortex to motor learning.

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Author information

Author/s: Gharbawie, Omar A (OA); Whishaw, Ian Q (IQ);

Affiliation: Department of Psychology and Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Dr., Lethbridge, Alberta T1K 3M4, Canada. omar.gharbawie(-atsign-)uleth.ca

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: Behavioural brain research (Behav Brain Res), published in Netherlands. (Language: eng)

Reference: 2006-Dec; vol 175 (issue 2) : pp 249-62

Dates: Created 2006/11/20; Completed 2007/01/11; Revised 2007/11/15;

PMID: 17049628, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Motor Cortex - physiopathology
Motor Skills - physiology
Movement - physiology
Rats
Rats, Long-Evans
Recovery of Function - physiology
Stroke - physiopathology; rehabilitation

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