THE ACTIVITY IN HUMAN AREAS V1 V2, V3, AND V5 DURING THE PERCEPTION OF COHERENT AND INCOHERENT MOTION/

We have used the technique of positron emission tomography to study an d compare the cortical activity produced when humans view a pattern of small squares moving incoherently with respect to one another and whe n the same pattern moves coherently and unidirectionally. A stationary version of the stimulus acted as a control. Our choice of paradigm wa s inspired by psychophysical models and physiological studies in the m acaque monkey which show that directionally selective cells in V5 resp ond optimally to unidirectional coherent motion, whereas those of V1 r espond to motion within their receptive fields, regardless of the moti on in surrounding parts. Our results show that human V1/V2, V3, and V5 are all activated by both types of motion stimuli. Incoherent motion, however, proved to be more effective than coherent motion in activati ng V1/V2 and V5. Thus the higher perceptual salience of unidirectional coherent motion in comparison to incoherent motion is not reflected b y any increased activation of human area V5. (C) 1997 Academic Press.