抄録
We re-focused on a basic question: what kind of information is encoded by primary motor cortical (M1) neurons during arm movements. While preceding studies used time-averaged neuronal activity for answering the question, we have focused on temporal neuronal activity to correlate it with time-varying variables related to arm movements. Two Japanese monkeys were trained to perform a traditional center-out task on a horizontal plane with holding a handle of a manipulandum. The hand trajectory was recorded together with M1 neuronal activity. We applied multiple linear regression analysis to correlate temporal unit activity with the following 4 different sets of movement variables; 1) kinematics variables (acceleration, velocity and position) in Cartesian (or extrinsic) coordinates (Ks), 2) kinematics variables in joint (or intrinsic) coordinates (Kj), 3) dynamics variables (inertial force, centrifugal force + Coriolis force and friction around the joints) in the extrinsic coordinates (Ds), and 4) dynamics variables in the intrinsic coordinates (Dj). Out of 191 task-related units which were responded to passive movements of elbow and/or shoulder joints, 125 (65%), 42 (22%), 16 (8%) and 8 (4%) units were best fitted with the Dj, Ds, Ks and Kj, respectively. This suggests that a majority of the M1 neurons encode dynamics variables of arm movements, with preference of joint torque variables in the intrinsic coordinates to hand force variables in the extrinsic coordinates. [Jpn J Physiol 55 Suppl:S177 (2005)]
