Centre for Neuroscience Studies, Queen’s University, Kingston, Canada; Graduate School of Medicine, The Hakubi Center for Advanced Research, Kyoto University, Kyoto, Japan
Douglas J Cook
Centre for Neuroscience Studies, Queen’s University, Kingston, Canada; Department of Surgery, Queen’s University, Kingston, Canada; Department of Surgery, Dalhousie University, Halifax, Canada
Centre for Neuroscience Studies, Queen’s University, Kingston, Canada; Department of Medicine, Queen’s University, Kingston, Canada; Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Canada
Several lines of research demonstrate that primary motor cortex (M1) is principally involved in controlling the contralateral side of the body. However, M1 activity has been correlated with both contralateral and ipsilateral limb movements. Why does ipsilaterally-related activity not cause contralateral motor output? To address this question, we trained monkeys to counter mechanical loads applied to their right and left limbs. We found >50% of M1 neurons had load-related activity for both limbs. Contralateral loads evoked changes in activity ~10ms sooner than ipsilateral loads. We also found corresponding population activities were distinct, with contralateral activity residing in a subspace that was orthogonal to the ipsilateral activity. Thus, neural responses for the contralateral limb can be extracted without interference from the activity for the ipsilateral limb, and vice versa. Our results show that M1 activity unrelated to downstream motor targets can be segregated from activity related to the downstream motor output.
