Human Parieto-Occipital Visual Cortex: Lack of Retinotopy and FovealMagnification

摘要

The authors recorded whole-scalp neuromagnetic responses to luminance stimuli ofvarying eccentricities in order to study visual representation in the parietal cortex. The stimuli were semicircles (5.5 deg in radius) presented at horizontal eccentricities varying from 0 to 16 deg. All stimuli evoked responses is the occipital and parietal areas. The waveform and distribution of the occipital responses varied with stimulus side (left, right) and eccentricity, whereas the parietal responses were remarkably similar to all stimuli. The neural generators of the parietal signals clustred with 1 cu. cm. in the medial parietoocipital sulcus and did not differ significantly between the stimuli. The strength of the parietal activation remained practically constant with increasing stimulus eccentricity, suggesting that the visual areas in the parietoocipital sulcus lack enhanced foveal representation.