Locations of floating microelectrode arrays implanted in both monkeys. Drawings were based on intraoperative photographs. In monkey X, arrays labeled F, G, H, I and J were implanted in the primary motor cortex (M1) and arrays C and D in the premotor cortex (PM). In monkey Y, arrays G, H, I and J were in M1 and arrays A, B, C and D were in PM. AS, arcuate sulcus; CS, central sulcus; SPS, superior precentral sulcus.