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Titolo:
TRANSFER OF GRADED POTENTIALS AT THE PHOTORECEPTOR INTERNEURON SYNAPSE
Autore:
JUUSOLA M; UUSITALO RO; WECKSTROM M;
Indirizzi:
UNIV OULU,DEPT PHYSIOL,KAJAANINTIE 52A SF-90220 OULU FINLAND
Titolo Testata:
The Journal of general physiology
fascicolo: 1, volume: 105, anno: 1995,
pagine: 117 - 148
SICI:
0022-1295(1995)105:1<117:TOGPAT>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
VISUAL-SYSTEM; BLOWFLY PHOTORECEPTORS; VENTRAL PHOTORECEPTORS; FLY PHOTORECEPTORS; POTASSIUM CHANNELS; MONOPOLAR NEURONS; LIGHT ADAPTATION; ORDER NEURONS; INSECT RETINA; COMPOUND EYE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
59
Recensione:
Indirizzi per estratti:
Citazione:
M. Juusola et al., "TRANSFER OF GRADED POTENTIALS AT THE PHOTORECEPTOR INTERNEURON SYNAPSE", The Journal of general physiology, 105(1), 1995, pp. 117-148

Abstract

To characterize the transfer of graded potentials and the properties of the associated noise in the photoreceptor-interneuron synapse of the blowfly (Calliphora vicina) compound eye, we recorded voltage responses of photoreceptors (R1-6) and large monopolar cells (LMC) evoked by: (a) steps of light presented in the dark; (b) contrast steps; and (c) pseudorandomly modulated contrast stimuli at backgrounds covering 6 log intensity units. Additionally, we made recordings from photoreceptor axon terminals. Increased light adaptation gradually changed the synaptic signal transfer from low-pass to band-pass filtering. This was accompanied by decreased synaptic delay and increased contrast gain, but the overall synaptic gain and the intrinsic noise (i.e., transmission noise) were reduced. Based on these results, we describe a descriptive synaptic model, in which the kinetics of the tonic transmitter (histamine) release from the photoreceptor axon terminals change with mean photoreceptor depolarization. During signal transmission, tonic transmitter release is augmented by voltage-dependent contrast-enhancing mechanisms in the photoreceptor axons that produce fast transients fromthe rising phases of the photoreceptor responses and add these enhanced voltages to the original photoreceptor responses. The model can predict the experimental findings and it agrees with the recently proposed theory of maximizing sensory information.

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Documento generato il 25/11/20 alle ore 18:50:17