Behaviorally Selective Engagement of Short-Latency Effector Pathways by Motor Cortex

What about humans?  If the motor cortex is not needed for walking in mice then why is my walking still screwed up?  Of course my pre-motor cortex is mostly dead also, no idea how much white matter damage there is underlying those cortex areas. Because I never got any objective damage diagnosis I have no idea what needs fixing.
http://www.cell.com/neuron/fulltext/S0896-6273(17)30594-9

Andrew Miri^10,Correspondence information about the author Andrew MiriEmail the author Andrew Miri

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Claire L. Warriner

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Jeffrey S. Seely

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Gamaleldin F. Elsayed

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John P. Cunningham

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Mark M. Churchland

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Thomas M. Jessell

¹⁰Lead Contact

Publication stage: In Press Corrected Proof

DOI: http://dx.doi.org/10.1016/j.neuron.2017.06.042

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Highlights

• •In mice, motor cortex is required for a trained forelimb task, but not walking
• •Motor cortex activates short-latency effector pathways only during the trained task
• •Distinct weighted sums of motor cortical firing patterns vary strongly in each task
• •This change could permit motor cortex to engage short-latency pathways differentially

Summary

Blocking motor cortical output with lesions or pharmacological inactivation has identified movements that require motor cortex. Yet, when and how motor cortex influences muscle activity during movement execution remains unresolved. We addressed this ambiguity using measurement and perturbation of motor cortical activity together with electromyography in mice during two forelimb movements that differ in their requirement for cortical involvement. Rapid optogenetic silencing and electrical stimulation indicated that short-latency pathways linking motor cortex with spinal motor neurons are selectively activated during one behavior. Analysis of motor cortical activity revealed a dramatic change between behaviors in the coordination of firing patterns across neurons that could account for this differential influence. Thus, our results suggest that changes in motor cortical output patterns enable a behaviorally selective engagement of short-latency effector pathways. The model of motor cortical influence implied by our findings helps reconcile previous observations on the function of motor cortex.