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Characterization of limb representation in the pig's motor cortex
David Bergeron1, Hugo Delivet-Mongrain2,3, Marco Bonizzato2,3,4,5
1Division of Neurosurgery, Université de Montréal, Montréal, Quebec, Canada.
Journal of Neurophysiology
|May 19, 2026
Summary
Pigs, valuable for neuroscience research, have a motor cortex with distinct forelimb and hindlimb representations. Forelimb control is direct, while hindlimb control involves indirect brainstem pathways.
Area of Science:
- Neuroscience
- Comparative Neurology
- Motor System Research
Background:
- Pigs are increasingly utilized in neuroscience due to their gyrencephalic brain, particularly for preclinical neuroprosthetic testing.
- Limited understanding of the porcine motor system hinders its use in comparative neuroscience research.
Purpose of the Study:
- To characterize the forelimb and hindlimb representation within the pig motor cortex.
- To compare the neural pathways controlling forelimb versus hindlimb movements in pigs.
Main Methods:
- Intracortical microstimulation (ICMS) was employed to map the motor cortex in three domestic pigs (Sus scrofa).
- Electrode depth, motor threshold, and limb responses (visual and electromyographic) were recorded for each stimulation site.
Main Results:
- A significant forelimb representation was identified in the pig motor cortex, exhibiting stereotypical contralateral responses.
- The hindlimb representation was smaller, located within the interhemispheric fissure, and required higher stimulation thresholds (280 ± 45 μA vs. 75 ± 25 μA for forelimb).
- Unilateral stimulation of the hindlimb motor cortex evoked bilateral hindlimb movements, suggesting polysynaptic control.
Conclusions:
- The porcine motor cortex directly commands forelimb movements via the corticospinal pathway.
- Cortical control of hindlimb movements in pigs likely involves polysynaptic pathways, such as the cortico-reticulospinal pathway, through the brainstem.
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