Comparison of movement-related activity in two cortical motor areas of primates.

Publisher Website
Google Scholar
Abstract
The distribution of neurons in the supplementary motor area (SMA) whose activity was related to forelimb and hindlimb movements was studied to provide a basis for comparing neuronal activity in the SMA and precentral motor area. Neurons related to forelimb and hindlimb movements were distributed both dorsally and ventrally on the medial surface of the cortex and in the upper bank of the cingulate sulcus. The locations of these 2 classes of neurons were separated anteroposteriorly without overlapping, with forelimb-related neurons occupying the anterior position and extending posteriorly toward the surface of the cingulate sulcus. In a 2nd series of experiments, neuronal activity in the forelimb part of the SMA and percentral motor area was recorded on alternate days to compare movement-related activity associated with wrist movements performed in response to visual, auditory and tactile signals. The intensity of the movement-associated neuronal activity was distinctly smaller in the SMA than in the precentral motor area. Onsets of neuronal activity in the SMA were not as well correlated with animal''s movement onsets as that in the precentral motor area. The SMA is more remote from the peripheral motor apparatus than the precentral motor area. The neuronal response times (the times from the visual and auditory movement cue signal to the onset of neuronal activity change) of SMA neurons were shorter than those of precentral neurons. Responses of some SMA neurons were temporally coupled to the visual or auditory signals, though these responses were observed only when the sensory signals called for a motor response.