Enriched rehabilitative training promotes improved forelimb motor function and enhanced dendritic growth after focal ischemic injury.
Chronic impairment of forelimb and digit movement is a common problem after stroke that is resistant to therapy. Previous studies have demonstrated that enrichment improves behavioral outcome after focal ischemia; however, postischemic enrichment alone is not capable of enhancing fine digit and forelimb function. Therefore, we combined environmental enrichment with daily skilled-reach training to assess the effect of intensive task-specific rehabilitation on long-term functional outcome. Rats were subjected to either endothelin-1-induced focal ischemia or sham surgery and subsequently designated to enriched-rehabilitation or standard-housing treatment groups starting 15 d after ischemia. Functional assessment of the affected forelimb at 4 and 9 weeks after treatment revealed that ischemic plus enrichment (IE) animals had improved approximately 30% on the staircase-reaching task and were indistinguishable from sham animals for both latency and foot faults in a beam-traversing task. In contrast, ischemic plus standard (IS) animals remained significantly impaired on both tasks. Interestingly, both ischemic groups (IE and IS) relied on the nonaffected forelimb during upright weight-bearing movements, a pattern that persisted for the duration of the experiment. Dendritic arborization of layer V pyramidal cells within the undamaged motor cortex was examined using a Golgi-Cox procedure. IE animals showed enhanced dendritic complexity and length compared with both IS and sham groups. These results suggest that enrichment combined with task-specific rehabilitative therapy is capable of augmenting intrinsic neuronal plasticity within noninjured, functionally connected brain regions, as well as promoting enhanced functional outcome.
Biernaskie
J
J
Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3V6. g83jab@mun.ca
Corbett
D
D
D000818:Animals; D002545:Brain Ischemia / Q000139:chemically induced / Q000503:physiopathology / Q000534:rehabilitation*; D003712:Dendrites / Q000502:physiology; D004195:Disease Models, Animal; D004777:Environment; D005552:Forelimb / Q000503:physiopathology*; D008297:Male; D009048:Motor Skills; D009473:Neuronal Plasticity; D026741:Physical Therapy Modalities / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D020127:Recovery of Function; D016896:Treatment Outcome