Fig. 3.

Examples of single cell activity and directional tuning. A: perievent average firing rates from example cells in M1, PMd, and PMv for reaches made in each direction. Left: firing surrounding the instruction cue. Right: firing surrounding the start of movement. B: Preferred direction for an M1 cell during the instruction (INS, black), reaction (RT, orange), and movement (MOVE, green) epochs plotted on a circle, where ray length is determined by the depth of cosine modulation in spikes per second. Preferred directions in each epoch for a cell from PMd and PMv are shown in C and D, respectively.