Movement-related cortical potentials: their relationship to the laterality, complexity and learning of a movement.

Movement-related cortical potentials (MRCPs) to self-paced unilateral movements of different laterality, complexity and practice level were recorded from 14 healthy subjects using the EMG onset as the trigger. The amplitudes at certain time points and slopes of linear regression lines fitted to 3 main shifts have been evaluated. In the early phase of MRCP the potential and slope values were symmetrically distributed around the midline maximum, which indicates that this part of MRCP can not originate from the primary motor area, which is in a contralateral relation with the movement, but from secondary motor areas (SMA and premotor areas). The changes in the voltage levels and slopes of this phase due to the changes in laterality, complexity and practice level of the movement show the relation of this activity with the abstract characteristics of the movement. The decrease of voltages and slope values in the later phases of MRCP in the complex task, which is replaced by higher voltages and slopes after a certain learning period was evaluated as a result of inhibition of associative movements via reafferent feedback signals occurring often in the first stages of learning period.