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Titolo:
THE DYNAMICS OF LIGHT ADAPTATION IN CAT HORIZONTAL CELL RESPONSES
Autore:
LANKHEET MJM; VANWEZEL RJA; PRICKAERTS JHHJ; VANDEGRIND WA;
Indirizzi:
UNIV ROCHESTER,CTR VISUAL SCI,274 MELIORA HALL ROCHESTER NY 14627 UNIV UTRECHT,DEPT COMPARAT PHYSIOL,UTRECHT BIOPHYS RES INST 3584 CH UTRECHT NETHERLANDS
Titolo Testata:
Vision research
fascicolo: 9, volume: 33, anno: 1993,
pagine: 1153 - 1171
SICI:
0042-6989(1993)33:9<1153:TDOLAI>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
RETINAL GANGLION-CELLS; FREQUENCY TRANSFER PROPERTIES; VERTEBRATE PHOTORECEPTORS; BACKGROUND ILLUMINATION; VISUAL TRANSDUCTION; TURTLE RETINA; CONES; PHOTOTRANSDUCTION; MECHANISM; CALCIUM;
Keywords:
LIGHT ADAPTATION DYNAMICS; HORIZONTAL CELL; RETINA; CAT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
43
Recensione:
Indirizzi per estratti:
Citazione:
M.J.M. Lankheet et al., "THE DYNAMICS OF LIGHT ADAPTATION IN CAT HORIZONTAL CELL RESPONSES", Vision research, 33(9), 1993, pp. 1153-1171

Abstract

In order to model the dynamic properties of light adaptation processes in cat horizontal (H-) cells, the time course of the gain adjustmentfollowing changes in the mean illumination level was studied. H-cell responses were recorded intracellularly in the optically intact, in vivo, eye of the cat. The light stimulus consisted of two spots, a largebackground spot (8.8 deg diameter) and a concentrically arranged smaller test spot (3.9 deg). The background was either square wave or sinewave modulated in intensity at a frequency of 0.2-1 Hz. The instantaneous value of the response gain was measured with brief flashes (10 msec) of the test spot, generated repetitively at a frequency of 5 or 10Hz. Modulation of the background intensity, at a constrast of 0.6 andin the photopic range, effectively induces a modulation of the gain. The readjustment of the gain by a stepwise increase or decrease in background illumination is completed within about 200 msec. The amplitudeof the gain modulation due to a 0.5 Hz background flicker is quantitatively comparable to that measured between steady illumination levels. Dynamic changes of the gain at low frequency stimuli therefore, have to be taken into account in modelling H-cell responses. For sinusoidalmodulations of the background luminance the time course of gain adjustment is quantified by the phase shift of the gain modulation relativeto background intensity modulation. The results, together with those described in two preceding papers, are used to test and discuss several light adaptation models that have been proposed previously. It was found that light adaptation in cat H-cells is described more adequatelyby a de Vries-Rose type of adaptation model than by a Weber type of light adaptation.

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Documento generato il 03/12/20 alle ore 12:06:44