SELECTIVE ACTIVATION OF HUMAN CORTICAL AREA V5A BY A ROTATING VISUAL STIMULUS IN FMRI - IMPLICATION OF ATTENTIONAL MECHANISMS

THE human homologue of area V5A of rotation-selective cells in the mon key medial superior temporal area (MST) was identified using functiona l magnetic resonance imaging (fMRI). It was located within the border region of occipito-temporo-parietal cortex, in four of 10 subjects on both sides, and on the right or left side in three subjects each. The stimulus was a black-and-white sine-modulated windmill presented eithe r stationary or in rotation phases of Is duration. Areas V1-V3 did not show up with this paradigm. Focusing attention by mentally counting t he number of rotation phases ensured high signal intensity in V5A, whe reas moving attention away by counting electric stimuli to the wrist d iminished it despite persistent fixation of to the centre of the windm ill.