ISSN:
1432-1106
Keywords:
Lateral geniculate nucleus
;
Binocular inhibition
;
Inhibitory receptive fields
;
Binocular correspondence
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The majority of cells in the dorsal nucleus of the lateral geniculate body (LGNd) in the cat have two receptive fields: one for each eye. Of the cells tested for binocularity (113), only 21 (18%) were purely monocular. The remainder had receptive fields for the non-dominant eye, the great majority of which (81 or 88%) were purely inhibitory and only 11 (12%) were excitatory. Cells with receptive fields for the non-dominant eye were found in all three laminae (A, A1 and B) of the LGNd. The proportion of inhibitory receptive fields for the non-dominant eye was slightly greater when the dominant eye was ipsilateral (77%) than when it was contralateral (68%). The distribution of the binocular receptive field pairs about points of exact correspondence in the visual field had a standard deviation of about 0.9° in both horizontal and vertical directions. The properties of the inhibitory receptive fields were studied with moving slits of light and stationary flashing spots. Most of the fields were purely inhibitory and varied in size from 1.5° to 6° across. There were no specific stimulus requirements other than a change in contrast within the receptive field. The inhibitory effect was usually fairly weak, the spontaneous discharge of the neuron being inhibited much more readily than the driven discharge. The latency of the inhibition to a stationary flashing spot was about 50 msec, the inhibition was maximal about 20 msec after the onset and lasted up to about 400 msec. Binocular inhibition is not mediated by a corticogeniculate pathway from the visual areas since it survives removal of areas 17, 18 and 19 and the middle suprasylvian gyrus. It was concluded that the most likely mechanism was via interneurons whose axons cross the borders from one cell layer to another.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00234085
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