Is Remodelling of Corticospinal Tract Terminations Originating in the Intact Hemisphere Associated with Recovery following Transient Ischaemic Stroke in the Rat?

Following a stroke, the brain can sometimes reorganize itself to compensate for lost function. One theory is that the corticospinal tract (CST) from the healthy side of the brain sprouts new connections in the spinal cord. This study investigates whether this sprouting occurs in rats that have had a subcortical stroke, which is a stroke that primarily affects areas beneath the cortex. Rats were subjected to a procedure that caused a temporary blockage of a brain artery, resulting in subcortical strokes. After 28 days, when the rats had shown some recovery, a tracer was injected into the motor cortex of the healthy side of the brain to track the CST terminals in the spinal cord. The researchers then compared the number of CST terminals in the spinal cord of the stroke rats with those of healthy rats. The study found that there was no significant difference in the number of CST terminals from the healthy side of the brain in the spinal cord between the stroke rats and the healthy rats. This suggests that, in this model of subcortical stroke, sprouting of the CST from the non-damaged side of the brain is not a major mechanism of functional recovery.

• 1
  Rats with subcortical infarcts exhibited sensorimotor deficits and impaired neurological function in the early phase after MCAO but recovered over time.
• 2
  Partial loss of PKC-γ contralateral to the ischaemic hemisphere was observed in MCAO rats, indicating injury to the CST.
• 3
  The number of axon terminals in the cervical spinal cord which originated in the contralesional cortex was not altered compared to shams, despite functional recovery.