Estimating receptive field size from fMRI data in human striate and extrastriate visual cortex

Functional magnetic resonance imaging (fMRI) was used to estimate the avera ge receptive field sizes of neurons in each of several striate and extrastr iate visual areas of the human cerebral cortex. The boundaries of the visua l areas were determined by retinotopic mapping procedures and were visualiz ed on flattened representations of the occipital cortex. Estimates of recep tive field size were derived from the temporal duration of the functional a ctivation at each cortical location as a visual stimulus passed through the receptive fields represented at that location. Receptive fields are smalle st in the primary visual cortex (V1). They are larger in V2, larger again i n V3/VP and largest of all in areas V3A and V4. In all these areas, recepti ve fields increase in size with increasing stimulus eccentricity. The resul ts are qualitatively in line with those obtained by others in macaque monke ys using neurophysiological methods.