Forelimb training drives transient map reorganization in ipsilateral motor cortex.

Area of Science:

• Neuroscience
• Motor Control
• Neuroplasticity

Background:

• Skilled motor training reorganizes the contralateral motor cortex.
• The role of the ipsilateral motor cortex in skilled motor control and its plasticity is less understood.

Purpose of the Study:

• To investigate how skilled motor training affects the ipsilateral motor cortex representations of the trained limb.
• To determine if motor cortex maps in the ipsilateral hemisphere undergo plasticity following training.

Main Methods:

• Rats were trained on an automated isometric pull task requiring skilled forelimb use.
• Intracortical microstimulation (ICMS) mapping was used to assess motor representations in the ipsilateral motor cortex after 3 and 6 months of training.

Main Results:

• Three months of training led to a significant expansion of the forelimb representation in the ipsilateral motor cortex.
• After six months, the forelimb representation size normalized, returning to levels similar to untrained controls.
• Forelimb map area did not correlate with task performance, indicating performance is maintained despite map normalization.

Conclusions:

• Skilled motor training induces plasticity in the ipsilateral motor cortex, with an initial expansion followed by normalization.
• Motor cortex map normalization suggests adaptive processes that maintain skilled motor performance.
• Findings offer insights into ipsilateral cortical changes during learning and potential applications for neurorehabilitation strategies.