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Titolo:
FAST-ACTING COMPRESSIVE AND FACILITATORY NONLINEARITIES IN LIGHT-ADAPTED FLY PHOTORECEPTORS
Autore:
WECKSTROM M; JUUSOLA M; UUSITALO RO; FRENCH AS;
Indirizzi:
DALHOUSIE UNIV,DEPT PHYSIOL & BIOPHYS HALIFAX NS B3H 4H7 CANADA UNIV OULU,DEPT PHYSIOL OULU FINLAND UNIV ALBERTA,DEPT PHYSIOL EDMONTON AB CANADA
Titolo Testata:
Annals of biomedical engineering
fascicolo: 1, volume: 23, anno: 1995,
pagine: 70 - 77
SICI:
0090-6964(1995)23:1<70:FCAFNI>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
BLOWFLY PHOTORECEPTORS; LOCUST PHOTORECEPTORS; CHANNELS; ADAPTATION; CALLIPHORA; LIMULUS; RETINA;
Keywords:
PHOTOTRANSDUCTION; LIGHT ADAPTATION; GAMMA FUNCTION; IMPULSE RESPONSE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
30
Recensione:
Indirizzi per estratti:
Citazione:
M. Weckstrom et al., "FAST-ACTING COMPRESSIVE AND FACILITATORY NONLINEARITIES IN LIGHT-ADAPTED FLY PHOTORECEPTORS", Annals of biomedical engineering, 23(1), 1995, pp. 70-77

Abstract

Light-adapted fly photoreceptor cells were stimulated with brief positive and negative contrast flashes (contrast = Delta I/I, I = intensity). Membrane potential responses to a wide range of flash intensities were well-fitted by a static nonlinearity followed by a compartmental model represented by a gamma function. However, the agreement improvedif one parameter of the gamma function, n, varied quadratically with input light intensity. Response amplitude and time to peak were estimated from the fitted parameters. Response amplitude varied approximately linearly with contrast but showed nonlinear compression with the largest negative flashes. Reducing the background light level by 3 decades or hyperpolarizing the cell electrically produced stronger nonlinearcompression with both contrast polarities. This is probably due to fast voltage-activated K+ channels. Responses to double flashes with varying time separations were well-fitted by summed gamma functions, allowing separation of the individual flash responses. There was no detectable time-dependent interaction between paired positive flashes at allseparations. However, the response to two negative flashes was greater than the linear prediction at short separations, and this facilitatory nonlinearity decayed with a time constant of about 1 msec. The facilitation is probably related to resonant behavior in light-adapted photoreceptors and may be due to an IP3-induced intracellular Ca2+ release.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 09:53:15