Variations of the visual responses of the superior colliculus in relation to body roll

A large percentage of the directional units of the superior colliculus of the curarized cat modify their response to a particular moving visual stimulus as a function of the position of rotation of the animal about its longitudinal axis.

Electrophysiological evidence for binocular disparity detectors in human visual system

Evoked potentials have been recorded from humans in response to two moving gratings presented stereoscopically to both eyes. The amplitude of the evoked potential is greater when the two gratings have slightly different spatial frequencies, which produces an apparent inclination of the binocularly fused image. The amplitude of the response is correlated with the degree of the perceived inclination.

Electrophysiological evidence for the existence of orientation and size detectors in the human visual system

1. The evoked potential in response to a grating alternating in phase at 8 c/s was recorded as a function of contrast from the occiput of man.2. It was found that a linear relation exists between the log. of contrast and the amplitude of the evoked potential.3. Extrapolation to zero amplitude voltage of the regression line between the amplitude of the evoked potential and log. contrast predicts the psychophysical threshold. This law was found to hold over the wide range of spatial frequencies tested.4. Below 3 c/deg the results are best fitted with two regression lines; one of these is generated from the foveal and the other from the parafoveal representation in the cortex.5. The slope of the regression lines was found to be almost independent of either the spatial frequency or the area of the stimulus grating.6. The slope of the regression lines could be markedly increased by using as a stimulus either two different spatial frequencies, or two different orientations, presented simultaneously.7. Using the evoked potential the selectivity to orientation was found to be so high that a channel was not influenced by another orientation 15 degrees away.8. The channels selectively sensitive to spatial frequency were highly selective and were not influenced by another spatial frequency one octave removed in spatial frequency.9. It is concluded that in man there exist neurones highly selective to both orientation and spatial frequency.

Neurophysiological localization of the vertical and horizontal visual coordinates in man

The amplitude of the potential evoked by a moving grating, recorded from the occipital scalp, is less when it is oblique compared with vertical and horizontal. This inequality is not found by recording the electroretinogram. Thus, orientational effects must arise between the site of origin of the electroretinogram and the evoked cortical response.