Effect of practice on brain activity: an investigation in top-level rifle shooters.

PURPOSE The study investigated the effect of motor experience on the brain activity associated with self-paced movement of the left and right index fingers. METHOD Movement-related cortical potentials (MRCP) are indices of cortical activation related to movement preparation and execution. MRCP were recorded in two groups of subjects: high-level rifle shooters and control subjects without any shooting experience. All subjects were right-handed. Four MRCP components were considered: Bereitschaftspotential (BP), negative slope (NS'), motor potential (MP), and reafferent positivity (RAP). The BP and NS' components, which emerged before movement onset, were associated with preparation for voluntary movements. RESULTS Differences between groups were found in the amplitude and latency of these components for right finger flexion (but not for left finger flexion). BP and NS' latencies were longer for shooters than for controls; amplitudes were smaller. In contrast, no difference was found between groups for MP and RAP amplitude or latency. Source analysis, based on a realistic model of the brain, showed with high reliability (97/% of variance explained) that the BP (time window: -1500 400 ms), NS' (-400 50 ms), MP (0 +100 ms) and RAP (+100 +200 ms) components were generated in the supplementary motor area, premotor area, primary motor area, and somatosensory area, respectively. No difference was found between groups regarding the localization of generators of all components. CONCLUSION Results are discussed in terms of neural economy of motor preparation due to the specific practice involved in shooting.