title: The lateral spread of light adaptation in cat horizontal cell responses.
abstract: To investigate the sites of light adaptation processes in the mammalian distal retina, we studied the lateral spread of adaptation signals in cone-driven cat horizontal (H-) cell responses. The size of the adaptation pool is compared to the receptive field for H-cell responses. H-cell activity was recorded intracellularly in the optically intact, in vivo eye. It is demonstrated that light adaptation as measured in H-cells is not a strictly local process. Background light falling outside a central test region effectively modulates the responses to a small test light, flashed on the receptive field center. The integration area for adaptation signals was quantitatively compared to the H-cell receptive field size by measuring the desensitizing effect of background light on the responses to a small centered test spot, as a function of background spot size. The area-adaptation function is comparable to the area-response function but has a slightly smaller length constant. Light adaptation in H-cell responses, therefore, reveals spread of adaptation over a large distance and is probably mediated through lateral interactions in the H-cell network rather than in the cones.
authors.affiliation: Utrecht Biophysics Research Institute, Utrecht University, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Lankheet
authors.forename: A W
authors.initials: AW
authors.lastname: Przybyszewski
authors.forename: W A
authors.initials: WA
authors.lastname: van de Grind
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D002415:Cats; D008027:Light; D008954:Models, Biological; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology; D012160:Retina / Q000166:cytology / Q000502:physiology*