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Updated: Jul 2, 2026
Transient Middle Cerebral Artery Occlusion Model of Neonatal Stroke in P10 Rats
Published on: April 21, 2017
Transient middle cerebral artery occlusion disrupts the forelimb movement representations of rat motor cortex
Omar A Gharbawie1, Preston T J A Williams, Bryan Kolb
1Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada.
Abstract:
Infarcts from proximal middle cerebral artery (MCA) stroke can produce impairments in motor function, particularly finger movements in humans and digit flexion in rats. In rats, the extent of neural damage may be limited to basal ganglia structures or may also include portions of the frontal and parietal cortex in severe cases. Although the primary motor cortex (M1) is anatomically spared in proximal MCA occlusion, its functional integrity is suspect because even a small subcortical infarct can damage neural circuits linking M1 with basal ganglia, brainstem, and spinal cord. This motivated the present study to investigate the neurophysiological integrity of M1 after transient proximal MCA occlusion. Rats, preoperatively trained and non-preoperatively trained to reach for food, received extensive reach training/testing with the contralateral-to-lesion paw for several weeks after MCA occlusion. The forelimb movement representations were assayed from the ipsilateral-to-lesion M1 with intracortical microstimulation approximately 10 weeks after MCA occlusion. Digit flexion was impaired during food grasping in rats with relatively small subcortical infarcts and was completely abolished in rats that sustained at least moderate subcortical damage. Corresponding forelimb movement representations ranged from abnormally small to absent. The results suggest that ischemia in subcortical territories of the MCA does not spare the neurophysiological properties of M1 despite its apparent anatomical intactness, probably because of damage sustained to its descending fibers. Thus, M1 dysfunction contributes to the impairments that ensue from proximal MCA occlusion, even when the infarct is limited to subcortical regions.
Insights
Middle cerebral artery (MCA) stroke impairs motor function. Even with anatomically intact primary motor cortex (M1), subcortical damage disrupts neural circuits, leading to M1 dysfunction and movement deficits.
Area of Science:
- Neuroscience
- Stroke Research
- Motor Function Recovery
Background:
- Proximal middle cerebral artery (MCA) stroke causes motor impairments, affecting finger movements and digit flexion.
- While the primary motor cortex (M1) may appear anatomically intact after MCA stroke, subcortical damage can compromise its functional integrity.
- Neural circuits connecting M1 with the basal ganglia, brainstem, and spinal cord are vulnerable to even small subcortical infarcts.
Purpose of the Study:
- To investigate the neurophysiological integrity of the primary motor cortex (M1) following transient proximal MCA occlusion.
- To determine if subcortical infarcts impact M1 function despite its anatomical preservation.
- To correlate M1 dysfunction with motor deficits observed after MCA stroke.
Main Methods:
- Transient proximal MCA occlusion was induced in rats.
- Rats underwent extensive reach training/testing with the contralateral paw post-stroke.
- Forelimb movement representations in the ipsilateral M1 were assessed using intracortical microstimulation approximately 10 weeks after occlusion.
Main Results:
- Digit flexion during food grasping was impaired in rats with small subcortical infarcts and abolished in those with moderate to severe subcortical damage.
- Forelimb movement representations in M1 were found to be abnormally small or absent in affected rats.
- M1 neurophysiological properties were compromised despite apparent anatomical intactness, suggesting damage to descending fibers.
Conclusions:
- Subcortical ischemia from MCA stroke negatively impacts M1 neurophysiological integrity, even when M1 itself is not directly infarcted.
- M1 dysfunction, resulting from damage to descending pathways, contributes significantly to motor impairments after MCA stroke.
- These findings highlight the importance of considering subcortical influences on M1 function in stroke recovery and rehabilitation strategies.
