Receptive fields of optic nerve fibres in the spider monkey

Abstract : Receptive fields of retinal ganglion cells were studied in the light-adapted spider monkey. All fields mapped with white light had a concentric arrangement sililar to that of the cat retinal ganglion cells, with a sharply demarcated 'on' centre surrounded by an antagonistic 'off' periphery, or the reverse. The smallest receptive field centres were found near the fovea, and the size of centres tended to increase with increasing distance from the fovea. The smallest centre had a diameter of 4 minutes of arc (corresponding to about 20 microns on the retina) and was located 4 degrees from the fovea; the largest centre had a diameter of 2 degrees. Three ganglion cells out of about 100 responded in a specific way to coloured stimuli. In these cells light of short wave-length produced an 'on' response and light of long wave-length evoked inhibition followed by an 'off' response. Transition between the two types of response occurred at about 500 millimicrons, light of this wave-length evoked only feebel 'off' responses. Very weak responses were obtained to white light, presumably owing to the antagonism between light of short and long wavelengths. (Author)