Abstract
It has been shown that neurons in the PMd and PMv respond to the appearance of visual signals, leading to an idea that these areas are involved in a visually guided motor behavior. To further examine the involvement of these areas in this behavior, we initially trained two monkeys (Macaca fuscata) to perform two visually guided tasks. 1) In a conditional visuomotor task, they were required to determine a forthcoming motor act based on identity of a visual object (i.e., indirect visuomotor processing). 2) In a visually guided reaching task, they were required to reach a visual target (i.e., direct visuomotor processing). We subsequently recorded neuronal activity from the PMd and PMv while they were performing the two tasks, which allowed us to compare response properties of each neuron under distinct modes of visuomotor processing. We found that PMd neurons were more responsive to the appearance of a visual cue requiring indirect visuomotor processing, and that the activity reflected an instructed motor act. We also found that PMv neurons, by contrast, were more responsive to the appearance of a visual target under the direct visuomotor processing, and that the activity reflected visuospatial feature of the target. These results suggest that the PMv and PMd are differently involved in the two modes of the visually guided motor behavior; the PMd and PMv are more involved in the indirect and direct visuomotor processing, respectively. [J Physiol Sci. 2008;58 Suppl:S191]
