title: Temporal evolution of both premotor and motor cortical tuning properties reflect changes in limb biomechanics.
abstract: A prevailing theory in the cortical control of limb movement posits that premotor cortex initiates a high-level motor plan that is transformed by the primary motor cortex (MI) into a low-level motor command to be executed. This theory implies that the premotor cortex is shielded from the motor periphery, and therefore, its activity should not represent the low-level features of movement. Contrary to this theory, we show that both dorsal (PMd) and ventral premotor (PMv) cortexes exhibit population-level tuning properties that reflect the biomechanical properties of the periphery similar to those observed in M1. We recorded single-unit activity from M1, PMd, and PMv and characterized their tuning properties while six rhesus macaques performed a reaching task in the horizontal plane. Each area exhibited a bimodal distribution of preferred directions during execution consistent with the known biomechanical anisotropies of the muscles and limb segments. Moreover, these distributions varied in orientation or shape from planning to execution. A network model shows that such population dynamics are linked to a change in biomechanics of the limb as the monkey begins to move, specifically to the state-dependent properties of muscles. We suggest that, like M1, neural populations in PMd and PMv are more directly linked with the motor periphery than previously thought.
authors: Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois; Department of Electrical Engineering and Computer Science, Milwaukee School of Engineering, Milwaukee, Wisconsin.
authors: Aaron J
authors: AJ
authors: Suminski
authors: Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois;
authors: Philip
authors: P
authors: Mardoum
authors: Department of Pharmacology, University of Oxford, Oxford, United Kingdom;
authors: Timothy P
authors: TP
authors: Lillicrap
authors: Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois; Committee on Computational Neuroscience, University of Chicago, Chicago, Illinois; and nicho@uchicago.edu.
authors: Nicholas G
authors: NG
authors: Hatsopoulos
mesh_terms: D000818:Animals; D001132:Arm / Q000502:physiology*; D003198:Computer Simulation; D056344:Executive Function / Q000502:physiology*; D005260:Female; D008253:Macaca mulatta; D008297:Male; D008959:Models, Neurological; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D013997:Time Factors
keywords: dorsal premotor cortex; limb biomechanics; primary motor cortex; ventral premotor cortex