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Titolo:
The effects of temporal noise and retinal illuminance on foveal flicker sensitivity
Autore:
Rovamo, J; Raninen, A; Donner, K;
Indirizzi:
Cardiff Univ, Dept Optometry & Vis Sci, Cardiff CF1 3XF, S Glam, Wales Cardiff Univ Cardiff S Glam Wales CF1 3XF Cardiff CF1 3XF, S Glam, Wales Univ Helsinki, Dept Physiol, Inst Biomed, FIN-00014 Helsinki, Finland UnivHelsinki Helsinki Finland FIN-00014 ed, FIN-00014 Helsinki, Finland Univ Helsinki, Dept Biosci, FIN-00014 Helsinki, Finland Univ Helsinki Helsinki Finland FIN-00014 ci, FIN-00014 Helsinki, Finland
Titolo Testata:
VISION RESEARCH
fascicolo: 3, volume: 39, anno: 1999,
pagine: 533 - 550
SICI:
0042-6989(199902)39:3<533:TEOTNA>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
SPATIOTEMPORAL FREQUENCY RESPONSES; TOAD BUFO-MARINUS; GANGLION-CELLS; LIGHT-ADAPTATION; CONTRAST SENSITIVITY; GRATING AREA; PATTERN-DISCRIMINATION; ELECTRICAL RESPONSE; SPATIAL INTEGRATION; PRIMATE RETINA;
Keywords:
human visual system; modelling; root-mean-square flicker sensitivity; temporal noise; retinal illuminance; quantal noise; light-adaptation; photoreceptors; lateral inhibition; temporal matched filter;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
78
Recensione:
Indirizzi per estratti:
Indirizzo: Rovamo, J Cardiffalesv, Dept Optometry & Vis Sci, POB 905, Cardiff CF1 3XF, S Glam, W Cardiff Univ POB 905 Cardiff S Glam Wales CF1 3XF 3XF, S Glam, W
Citazione:
J. Rovamo et al., "The effects of temporal noise and retinal illuminance on foveal flicker sensitivity", VISION RES, 39(3), 1999, pp. 533-550

Abstract

We measured foveal flicker sensitivity with and without external added temporal noise at various levels of retinal illuminance and described the datawith our model of flicker sensitivity comprising: (i) low-pass filtering of the flickering signal plus external temporal and/or quantal noise by the modulation transfer function (MTF) of the retina (R); (ii) high-pass filtering in proportion to temporal frequency by the MTF of the postreceptoral neural pathways (P); (iii) addition of internal white neural noise; and (iv) detection by a temporal matched filter. Without temporal noise flicker sensitivity had a band-pass frequency-dependence at high and medium illuminances but changed towards a low-pass shape above 0.5 Hz at low luminances, in agreement with earlier studies. In strong external temporal noise, however, the flicker sensitivity function had a low-pass shape even at high and medium illuminances and flicker sensitivity was consistently lower with noise than without. At low luminances flicker sensitivity was similar with and without noise. An excellent fit of the model was obtained under the assumptionthat the only luminance-dependent changes were increases in the cut-off frequency (f(c)) and maximum contrast transfer of R with increasing luminance. The results imply the following: (i) performance is consistent with detection by a temporal matched filter, but not with a thresholding process based on signal amplitude; (ii) quantal fluctuations do not at any luminance level become a source of dominant noise present at the detector; (iii) the changes in the maximum contrast transfer reflect changes in retinal gain, which at low to moderate luminances implement less-than-Weber adaptation, witha 'square-root' law at the lowest levels; (iv) the changes off, as function of mean luminance closely parallels time scale changes in cones, but the absolute values off, are lower than expected from the kinetics of monkey cones at all luminances; (v) the constancy of the high-pass filtering function P indicates that surround antagonism does not weaken significantly with decreasing light level. (C) 1998 Elsevier Science Ltd. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/07/20 alle ore 01:49:06