First published on ScienceDaily.com

Nagoya City University (NCU) researchers have revealed an interaction between cortico-brainstem pathways during training-induced recovery in stroke model rats, providing valuable insights for improving rehabilitation methods.

Upper limb hemiparesis often occurs after ischemic or hemorrhagic stroke. Unilateral upper extremity impairment can substantially disturb patients’ ability to complete activities of daily living. Therefore, continuous improvement of rehabilitation methods is needed to achieve more positive long-term outcomes among survivors.

Researchers at NCU have identified the dynamic recruitment of the “cortex-to-brainstem” pathways via post-stroke intensive rehabilitation and its contribution to the recovery of impaired forelimb function in intracerebral hemorrhage (ICH) model rats. This crucial finding could provide new insights enabling the improvement of rehabilitative methods for humans.

Stroke often affects the primary network from the cortex to the spinal cord, causing severe ongoing motor deficits. Rehabilitation promotes the recovery of impaired motor function, which is believed to be due to reorganization of the residual neural circuits. However, how the circuits are recruited in rehabilitation-induced recovery remains unclear.

To investigate the mechanisms underlying these phenomena, the NCU team used an ICH rat model in which almost 90% of the cortico-spinal tract is destroyed, causing changes in other motor-related circuits. “We previously found abundant newly formed connections from the motor cortex to the red nucleus in rehabilitated rats,” first author Akimasa Ishida explains. “Interestingly, we also uncovered an increase in the “cortex-to-reticular formation” pathway in trained rats when the “cortico-to-red nucleus” pathway failed to function, using a double-viral infection technique during rehabilitation.”

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