Neural correlates of advance movement preparation: a dipole source analysis approach

This study examined cortical motor structures that are involved in preprogr amming and execution of movements. In two independent experiments a respons e precuing task was employed that combined the recording of movement-relate d brain potentials (MRPs) with spatio-temporal source localization. Behavio ral and MRP results indicated the utilization of advance information about movement direction and hand. Dipole source modeling of foreperiod MRPs reve aled a reliable three-dipole solution with sources located in lateral and m edial brain regions anterior to the precentral gyrus. These dipoles were lo cated in the lateral premotor area (PMA) and supplementary/cingulate motor areas (SMA/CMA). Activity of the medial dipole increased with the extent of advance motor preparation, whereas lateral dipole activity revealed parall el preparation of both response hands when only partial information about m ovement direction was available. The dissociation in the strength and the o nset of medial and lateral dipole activity indicated two phases of motor pr eparation. We propose that medial motor areas like SMA and CMA are involved in the assembling and selection of abstract movement programs, whereas lat eral PMA and primary motor cortex are involved in effector-specific motor p reparation. (C) 2001 Elsevier Science B.V. All rights reserved.