ERP correlates of linear hand movements in a motor reproduction task.

Blindfolded participants performed one-dimensional movements towards a mechanical stop and back to the start. After a varying delay, they had to reproduce the encoded target position by a second mechanically unrestricted movement. Average event-related potentials accompanying the "encoding" and the "reproduction" movements revealed a biphasic waveshape over primary sensorimotor areas. The first negative deflection was the gradually increasing motor potential (MP) that precedes movement onset. This was followed by a second negative component (N4) starting about 100 ms after movement onset. Its amplitude and latency increased with increasing movement distance and reached its maximum in unrestricted movements (i.e., during reproduction) shortly before the deceleration peak. These results show that rapid hand movements are accompanied by non-continuous and highly distance specific activity changes measured over the sensorimotor cortex.