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Titolo:
In vivo calcium accumulation in presynaptic and postsynaptic dendrites of visual interneurons
Autore:
Durr, V; Egelhaaf, M;
Indirizzi:
Univ Bielefeld, Fak Biol, Abt Biokybernet & Theoret Biol, Lehrstuhl Neurobiol, D-33501 Bielefeld, Germany Univ Bielefeld Bielefeld Germany D-33501 iol, D-33501 Bielefeld, Germany Australian Natl Univ, Res Sch Biol Sci, Ctr Visual Sci, Canberra, ACT 2600, Australia Australian Natl Univ Canberra ACT Australia 2600 rra, ACT 2600, Australia
Titolo Testata:
JOURNAL OF NEUROPHYSIOLOGY
fascicolo: 6, volume: 82, anno: 1999,
pagine: 3327 - 3338
SICI:
0022-3077(199912)82:6<3327:IVCAIP>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOTION-SENSITIVE INTERNEURONS; INTRINSIC ELECTROPHYSIOLOGICAL CHARACTERISTICS; NEOCORTICAL PYRAMIDAL NEURONS; PLATE TANGENTIAL CELLS; LOBULA PLATE; HORIZONTAL CELLS; GAIN-CONTROL; RESPONSE CHARACTERISTICS; SYNAPTIC INFORMATION; SENSORY INTERNEURONS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
66
Recensione:
Indirizzi per estratti:
Indirizzo: Durr, V Univ Bielefeld, Fak Biol, Abt Biokybernet & Theoret Biol, Lehrstuhl Neurobiol, Postfach 10 01 31, D-33501 Bielefeld, Germany Univ Bielefeld Postfach 10 01 31 Bielefeld Germany D-33501 ermany
Citazione:
V. Durr e M. Egelhaaf, "In vivo calcium accumulation in presynaptic and postsynaptic dendrites of visual interneurons", J NEUROPHYS, 82(6), 1999, pp. 3327-3338

Abstract

In this comparative in vivo study of dendritic calcium accumulation, we describe the time course and spatial integration properties of two classes ofvisual interneurons in the lobula plate of the blowfly. Calcium accumulation was measured during visual motion stimulation, ensuring synaptic activation of the neurons within their natural spatial and temporal operating range. The compared cell classes, centrifugal horizontal (CH) and horizontal system (HS) cells, are known to receive retinotopic input of similar direction selectivity, but to differ in morphology, biophysics, presence of dendrodendritic synapses, and computational task. 1) The time course of motion-induced calcium accumulation was highly invariant with respect to stimulus parameters such as pattern contrast and size. In HS cells, the rise of [Ca2+](i) can be described by a single exponential with a time constant of 5-6 s. The initial rise of [Ca2+](i) in CH cells was much faster (tau approximate to 1 s). The decay time constant in both cell classes was estimated to be at least 3.5 times longer than the corresponding rise time constant. 2) The voltage-[Ca2+](i) relationship was best described by an expansive nonlinearity in HS cells and an approximately linear relationship in CH cells. 3) Both cell classes displayed a size-dependent saturation nonlinearity of the calcium accumulation. Although in CH cells calcium saturation was indistinguishable from saturation of the membrane potential, saturation of the two response parameters differed in HS cells. 4) There was spatial overlap of thecalcium signal in response to nonoverlapping visual stimuli. Both the areaand the amplitude of the overlap profile was larger in CH cells than in HScells. Thus calcium accumulation in CH cells is spatially blurred to a greater extent than in HS cells. 5) The described differences between the two cell classes may reflect the following computational tasks of these neurons: CH cells relay retinotopic information within the lobula plate via dendritic synapses with pronounced spatial low-pass filtering. HS cells are output neurons of the lobula plate, in which the slow, local calcium accumulation may be suitable for local modulatory functions.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/07/20 alle ore 21:07:40