Figure 1. Experimental set-up and protocol.

A monitor was placed directly in front of the subject. Movements of the subject's hand were translated into movements of a cursor on the monitor. The subject was required to move the cursor into the central circle (home position) in response to visual and audio cues for a period of about 2 s after which an unknown target was lit. The subject was requested to move directly to the target and hold that position. The inset illustrates the path of the cursor movement from the home position to the target. Simultaneously, single unit activity was recorded from the radial nerve.