Effects of image motion in the dorsal premotor cortex during planning of an arm movement.

This study examined whether neuronal activity in the dorsal premotor cortex (PMd) covaries with image motion or actual movement of the arm while planning a target-capturing task when the motor task is guided by an image of the moving arm. For this purpose, we trained a monkey to capture a target on a video screen with the part of the arm displayed on the screen. The target-capturing body part was either the right or left side of the hand image. Because the actual arm movement was invisible, the motor task was guided by the arm image, which was at times right-left inverted on the screen. We found that neuronal activity in the PMd predominantly reflected arm-image movement rather than the actual arm movement, and for half of PMd neurons, the activity differed depending on the target-capturing body-part defined in the right or left side of the arm image.