Distinguishing neural sources of movement preparation and execution. An electrophysiological analysis.

The present study examined lateralized event-related potentials (L-ERPs) associated with movement preparation and execution. In a response precuing task that involved hand and foot movements a precue conveyed either information about side and effector, side alone, or no information. Advance movement preparation was indicated by RT shortening with increasing amount of precue information. L-ERPs revealed during the preparatory interval an initial parietal activity when movement side was precued. Later in the preparatory interval L-ERPs revealed a polarity inversion for foot versus hand movements when effector and side were specified in advance. This polarity inversion showed up also in execution-related L-ERP waveforms. Comparison of preparation- versus execution-related brain signals yielded topographic differences and dissimilar dipole sources for hand-related L-ERP activity. We take present findings to indicate that brain generators within the parietal lobe and anterior MI are hierarchically related to precue-induced motor preparation, whilst posterior MI is associated with motor execution functions.