Abstract
In our previous study, temporal activity of single neurons of the primary motor cortex (MI) was correlated with kinematics or dynamics variables of arm movements using a multiple linear regression analysis. The present study extended the analysis to the dorsocaudal premotor cortex (PMdc) and compared the results with those of MI. As explanation variables, we used the following four types of variables sets (or models); 1) kinematics variables represented in Cartesian coordinates (model Kc), 2) those in joint coordinates (model Kj), 3) dynamics variables in Cartesian coordinates (model Dc) and 4) those in joint coordinates (model Dj). The analysis was applied to 189 MI and 52 PMdc units that responded to passive movements of the shoulder and/or elbow joints or maneuver manipulations of the muscles controlling these joints. Each unit was classified into one of the four types according to the model that best fitted the unit. About 85% neurons belonged to either of the dynamics types (i.e., type Dc or Dj) with predominance of type Dj, and the ratio of each type of neurons was similar in MI and PMdc. Moreover, activity of about 80% of the neurons preceded the arm movements, and this was observed commonly for MI and PMdc neurons. These results suggest that MI and PMdc neurons receiving proprioceptive information share similar roles in the execution of manual reaching movement. [J Physiol Sci. 2006;56 Suppl:S191]
