Experience-dependent neural plasticity in the adult damaged brain

Abstract

Behavioral experience is at work modifying the structure and function of the brain throughout the lifespan, but it has a particularly dramatic influence after brain injury. This review summarizes recent findings on the role of experience in reorganizing the adult damaged brain, with a focus on findings from rodent stroke models of chronic upper extremity (hand and arm) impairments. A prolonged and widespread process of repair and reorganization of surviving neural circuits is instigated by injury to the adult brain. When experience impacts these same neural circuits, it interacts with degenerative and regenerative cascades to shape neural reorganization and functional outcome. This is evident in the cortical plasticity resulting from compensatory reliance on the "good" forelimb in rats with unilateral sensorimotor cortical infarcts. Behavioral interventions (e.g., rehabilitative training) can drive functionally beneficial neural reorganization in the injured hemisphere. However, experience can have both behaviorally beneficial and detrimental effects. The interactions between experience-dependent and injury-induced neural plasticity are complex, time-dependent, and varied with age and other factors. A better understanding of these interactions is needed to understand how to optimize brain remodeling and functional outcome.

Learning outcomes: Readers will be able to describe (a) experience effects that are maladaptive for behavioral outcome after brain damage, (b) manipulations of experience that drive functionally beneficial neural plasticity, and (c) reasons why rehabilitative training effects can be expected to vary with age, training duration and timing.

Copyright © 2011 Elsevier Inc. All rights reserved.

Figures

Fig. 1

Examples of mice (A, B) and rats (C, D) performing motor skills, including an acrobatic task (A) pasta handling tasks (B, C) and a skilled reaching task (D). (The mouse in B is standing on a mirror.) These types of tasks are used to study neurobiology of motor skill learning and recovery from upper extremity impairments.

Fig. 2

An example of a mouse forelimb representation area in the motor cortex, overlaid to scale on a schematic mouse brain. Each square represents a 250 × 250 μm area in which a movement was evoked with micro-current delivery into the center of the square. CFA: caudal forelimb area; RFC: caudal forelimb area.