Efficacy of Rehabilitative Experience Declines with Time after Focal Ischemic Brain Injury

Abstract

To maximize the effectiveness of rehabilitative therapies after stroke, it is critical to determine when the brain is most responsive (i.e., plastic) to sensorimotor experience after injury and to focus such efforts within this period. Here, we compared the efficacy of 5 weeks of enriched rehabilitation (ER) initiated at 5 d (ER5), ER14, or ER30 after focal ischemia, as judged by functional outcome and neuromorphological change. ER5 provided marked improvement in skilled forelimb reaching ability and ladder-rung-and narrow-beam-walking tasks and attenuated the stroke-induced reliance on the unaffected forepaw for postural support. ER14 provided improvement to a somewhat lesser extent, whereas recovery was diminished after ER30 such that motor function did not differ from ischemic animals exposed to social housing.To examine potential neural substrates of the improved function, we examined dendritic morphology in the undamaged motor cortex because our previous work (Biernaskie and Corbett, 2001) suggested that recovery was associated with enhanced dendritic growth in this region. ER5 increased the number of branches and complexity of layer V neurons compared with both social housing and control animals. Dendritic arbor after ER14 (although increased) and ER30 did not differ from those exposed to social housing. These data suggest that the poststroke brain displays heightened sensitivity to rehabilitative experience early after the stroke but declines with time. These findings have important implications for rehabilitation of stroke patients, many of whom experience considerable delays before therapy is initiated.

Early Poststroke Experience Differentially Alters Periinfarct Layer II and III Cortex

“…Similar increases, though not reaching statistical significance, were observed in both perilesional striatum and contralesional forelimb cortex (Figure 2) similar to the architectural changes previously noted. 3,4 These findings indicate that a combination of environmental enrichment and task-specific rehabilitation targeting the primary functional deficit (i.e. skilled reaching as demonstrated in our previous reports) 4,5 most effectively increases neuronal activity around the lesion and in the intact hemisphere.…”

Enhancing Rehabilitative Therapies with Vagus Nerve Stimulation

“…Rehabilitative strategies have the highest potential to improve functional recovery after stroke when delivered early, and efficacy diminishes substantially with increasing time after stroke [62][63][64][65]. A study conducted by Khodaparast et al [66] sought to evaluate whether VNS paired with rehabilitative training would be effective after a long delay between ischemic lesion and therapy initiation.…”

Effects of treadmill exercise on cerebral angiogenesis and MT1‐MMP expression after cerebral ischemia in rats

“…More and more evidences show that MT1‐MMP take action in the beginning of vascular matrix dissolution, endothelial cell growth, vascular remodeling and ultimately in angiogenesis (Biernaskie, Cheruenko, & Corbett, 2004). Meanwhile, MT1‐MMP plays a critical role in stabling the vessels, reducing leakage, and promoting regeneration after vascular ischemia (Sounni et al., 2010).…”