The impact of learning on brain functional laterality has not been systematically investigated. We em- ployed an event-related functional magnetic resonance im- aging combined with a delayed sequential movement task to investigate brain activation pattern and laterality during a transient practice in 12 subjects. Both hemispheres, involving motor areas and posterior parietal cortex, were engaged during motor preparation and execution, with larger activa- tion volume in the left hemisphere than in the right. Activa- tion volume in these regions significantly decreased after a transient practice, with more reduction in the right hemi- sphere resulting increase in left lateralization. The theoretical implications of these findings are discussed in relation to the physiological significance of brain functional laterality.
