AsianScientist (Mar. 1, 2016) – Researchers have pinpointed the neural pathways that respond to physiotherapy after brain damage caused by stroke. Their findings, published in the Journal of Neuroscience, could pave the way for better rehabilitative methods for humans.
Each year millions of people worldwide suffer from stroke, often causing paralysis by lesioning the corticospinal tract which connects the motor cortex and spinal cord. While some may recover completely, the majority of survivors will experience some form of impairment that requires a lengthy process toward partial or full recovery of functioning.
Intensive rehabilitation is known to be a promising method of promoting functional recovery via the reorganization of lesioned brain circuits. Therefore, continuous improvement of rehabilitation methods is needed to ensure more positive long-term outcomes among survivors. However, the causal relationship between rehabilitation-induced changes of the brain circuits and functional recovery remains unproven.
To validate this relationship, researchers from Japan’s National Institute for Physiological Sciences (NIPS) and Nagoya City University (NCU) used an intracerebral hemorrhage (ICH) rat model to investigate the mechanisms of the therapeutic effects of intensive rehabilitative training.
“We found substantial functional recovery of the paralyzed forelimb when applying forced impaired limb use (or FLU) as rehabilitation,” explained first author Akimasa Ishida, an assistant professor at NCU. “We also uncovered the abundant newly formed connections from the motor cortex to the red nucleus in FLU-treated rats.”
To test the contribution of the formation of new cortex-to-red nucleus connections to functional recovery, the researchers selectively blocked the target pathway using a recently developed double-viral infection technique in rats that experienced recovery. After a blockade of the cortex-to-red nucleus connections, deficiency of the forelimb function reappeared in rehabilitated rats.
The results demonstrate that the rehabilitation-induced reorganization of the damaged brain circuits (i.e., robust increase of the cortex-to-red nucleus connections) is responsible for functional recovery.
“We provided direct proof of the causal link between the change of the brain circuits and the recovery of functions by rehabilitation,” corresponding author Professor Tadashi Isa says. “Further investigation on the finer details of the recovery process induced by FLU will help clinicians, physiotherapists, and patients to combat the devastating effects of stroke.”
The article can be found at: Ishida et al. (2016) Causal Link between the Cortico-Rubral Pathway and Functional Recovery through Forced Impaired Limb Use in Rats with Stroke.
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Source: National Institutes of Natural Sciences; Photo: Michelle Tribe/Flickr/CC.
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