Visual Event-Related Potentials During Movement Imagery and the Dipole Analysis

Visual event-related potentials during an oddball paradigm with movement imagery tasks were recorded in 10 right-handed subjects from 32 scalp electrodes. Rare targets and non-targets elicited early (P3e) and late (P3l) P300 components. In the P3e there was no difference between the rare target and non-target. In the right-imagery task the rare target P3l amplitude was larger than the rare non-target one, whereas the rare non-target P3l amplitude was larger than the rare target one in the left-imagery task. Some of the 4 equivalent current dipole (ECD) sources were located at the subcortical regions, the cerebellum and the cingulate cortex, common to the P3e and the P3l. Moreover, another P3e dipole was localized to the parietal regions, while that of the P3l dipoles to the contralateral premotor cortex. This difference between the P3e and P3l dipoles might reflect two different neural networks related with the transformation of coordinates from visual to motor space.