Synergistic Effects of Enriched Environment and Task-Specific Reach Training on Poststroke Recovery of Motor Function

• Published in: Stroke (1970) 2018-06, Vol.49 (6), p.1496-1503
• Main Authors: Jeffers, Matthew Strider, Corbett, Dale
• Format: Article
• Language: English
• ISSN: 0039-2499; 1524-4628
• DOI: 10.1161/STROKEAHA.118.020814

BACKGROUND AND PURPOSE—Reach training in concert with environmental enrichment provides functional benefits after experimental stroke in rats. The present study extended these findings by assessing whether intensive task-specific reach training or enrichment initiated alone would provide similar functional benefit. Additionally, we investigated whether the 70% recovery rule, or a combined model of initial poststroke impairment, cortical infarct volume, and rehabilitation intensity, could predict recovery in the single-pellet task, as previously found for the Montoya staircase. METHODS—Rats were trained on single-pellet reaching before middle cerebral artery occlusion via intracerebral injection of ET-1 (endothelin-1). There were 4 experimental groupsstroke+enrichment, stroke+reaching, stroke+enrichment+reaching, and sham+enrichment+reaching. Reaching rehabilitation utilized a modified Whishaw box that encouraged impaired forelimb reaching for 6 hours per day, 5 days per week, for 4 weeks. All treatment paradigms began 7 days after ischemia with weekly assessment on the single-pellet task during rehabilitation and again 4 weeks after rehabilitation concluded. RESULTS—Rats exposed to the combination of enrichment and reaching showed the greatest improvement in pellet retrieval and comparable performance to shams after 3 weeks of treatment, whereas those groups that received a monotherapy remained significantly impaired at all time points. Initial impairment alone did not significantly predict recovery in single-pellet as the 70% rule would suggest; however, a combined model of cortical infarct volume and rehabilitation intensity predicted change in pellet retrieval on the single-pellet task with the same accuracy as previously shown with the staircase, demonstrating the generalizability of this model across reaching tasks. CONCLUSIONS—Task-specific reach training and environmental enrichment have synergistic effects in rats that persist long after rehabilitation ends, and this recovery is predicted by infarct volume and rehabilitation intensity.