Movement related brain macropotentials and skilled motor actions

Background: Movement Related Brain Macropotentials (MRBMs) are electrical brain potentials occurring before, during and after skilled movements. Specific components of these potentials have been described and it has been reported that they can be recorded also during mental motor imagery and can be influenced by practice. To understand the exact relationship between MRBMs and skilled actions and to verify the hypothesis that motor training could modify MRBMs profile and influence specific components an experiment has been performed in which MRBMs were recorded during the execution of different skilled performance tasks and before and after a period of training. Methods: The experiment has been carried out with 31 healthy male subjects, divided into three groups. Eleven performed the Alert test (A), a simple reaction time test, in which the subject had to press in a precise sequence three keys of a keyboard when a figure appeared on the computer monitor. Ten subjects performed the Choice test (CH), a complex reaction time test, in which they had to press the three keys in a different order when one of two different figures appeared randomly on the screen. Ten subjects performed the Choice test with the addition of a Go/No-Go paradigm (CHNG) in which participants had also to repress an unsuitable response. All subjects were tested before and after 10 days of training. During the trials EEG, EMG and other physiological parameters were recorded. The time of the recorded test was divided into three periods: prestimulus, motor (premotor, motor action, motor completion) and postmotor. Data were collected, averaged and compared by appropriate statistical methods. Results: The time of EMG activation and Reaction Time (RT) were lower in A then in CH and CHNG. Training did not influenced A, but was followed by a significant reduction of RT in CH and CHNG. The profile of MRBMs was different in the motor period in the three tests. The duration of Premotor Potential (PMP), a positive wave recorded in the premotor component of the motor period, increased passing from A to CHNG, but after training, it was reduced only in the CHNG test. During motor action the duration of the negative wave Motor Cortex Potential (MCP) increased from A to CHNG and was reduced after training in all tests. In CHNG training reduced the latency of N1 and N2, the negative peaks recognizable in the MCP profile, and the latency of the Skilled Performance Positivity (SPP), a wave occurring in the postmotor period. Moreover, after training the period preceding the stimulus showed an increase of negativity in the last 200 msec. Conclusions: MRBMs can change their profile in relation to the characteristics of the test and the skilled motor action. The increase of duration and latency of the motor period waves, passing from A to CHNG, can be considered as picture of increased information processing and response selection brain activity. Moreover, training can affect the profile of the waves, reducing their duration and latency, particularly when the performance requires high mental effort. © 2009 by Nova Science Publishers, Inc.