Figure 1.

Visual responses of a typical premotor neuron with a tactile RF (hatched) on the forearm and hand, and a visual RF within 10 cm of the tactile RF. (A) On each trial, the arm contralateral to the neuron was fixed in one of two positions and the visual stimulus was advanced along one of four trajectories (1–4). For this neuron, the two arm positions were chosen to align the visual RF near the hand and forearm with trajectories 2 and 3. For other neurons, the arm was moved to different extents depending on the location of the visual RF, to better capture the movement of the visual RF with the arm. (B) Responses of the neuron to the four stimulus trajectories when the arm was visible to the monkey. When the arm was fixed on the right, the response was maximum at position 3. When the arm was fixed on the left, the maximum response moved to the left, to position 2. (C) Responses of the neuron when the arm was covered. The movement of the visual RF with the arm was reduced but not eliminated, indicating that the neuron combined both proprioceptive and visual information about the position of the arm. Each point is a mean of 10 trials. Error bars are standard error.