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Titolo:
IS THE INPUT TO A GABAERGIC OR CHOLINERGIC SYNAPSE THE SOLE ASYMMETRYIN RABBITS RETINAL DIRECTIONAL SELECTIVITY
Autore:
GRZYWACZ NM; TOOTLE JS; AMTHOR FR;
Indirizzi:
SMITH KETTLEWELL INST,2232 WEBSTER ST SAN FRANCISCO CA 94115 SMITH KETTLEWELL EYE RES INST SAN FRANCISCO CA 94115 UNIV ALABAMA,DEPT PHYSIOL OPT BIRMINGHAM AL 35294 UNIV ALABAMA,VIS SCI RES CTR BIRMINGHAM AL 00000 UNIV ALABAMA,DEPT PSYCHOL BIRMINGHAM AL 35294 UNIV ALABAMA,NEUROBIOL RES CTR BIRMINGHAM AL 35294
Titolo Testata:
Visual neuroscience
fascicolo: 1, volume: 14, anno: 1997,
pagine: 39 - 54
SICI:
0952-5238(1997)14:1<39:ITITAG>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
STARBURST AMACRINE CELLS; GABA-LIKE IMMUNOREACTIVITY; COMPLEX RECEPTIVE-FIELDS; GANGLION-CELLS; TURTLE RETINA; FUNCTIONAL INTERPRETATION; DENDRITIC MORPHOLOGY; MAMMALIAN RETINA; BIPOLAR CELLS; NEURONS;
Keywords:
DIRECTIONAL SELECTIVITY; RETINAL GANGLION CELLS; GABA; ACETYLCHOLINE; CHOLINESTERASE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
63
Recensione:
Indirizzi per estratti:
Citazione:
N.M. Grzywacz et al., "IS THE INPUT TO A GABAERGIC OR CHOLINERGIC SYNAPSE THE SOLE ASYMMETRYIN RABBITS RETINAL DIRECTIONAL SELECTIVITY", Visual neuroscience, 14(1), 1997, pp. 39-54

Abstract

We examined contrast, direction of motion, and concentration dependencies of the effects of GABAergic and cholinergic antagonists, and anticholinesterases on responses to movement of On-Off directionally selective (DS) ganglion cells of the rabbit's retina. The drugs tested werecurare and hexamethonium bromide (cholinergic antagonists), physostigmine (anticholinesterase), and picrotoxin (GABAergic antagonist). Theyall reduced the cells' directional selectivity, while maintaining their preferred-null axis. However, cholinergic antagonists did not blockdirectional selectivity completely even at saturating concentrations. The failure to eliminate directional selectivity was probably not dueto an incomplete blockade of cholinergic receptors. In a extension ofa Masland and Ames (1976) experiment, saturating concentrations of antagonists blocked the effects of exogenous acetylcholine or nicotine applied during synaptic blockade. Consequently, a noncholinergic pathway may be sufficient to account for at least some directional selectivity. This putative pathway interacts with the cholinergic pathway before spike generation, since physostigmine eliminated directional selectivity at contrasts lower than those saturating responses. This elimination apparently resulted from cholinergic-induced saturation, since reduction of contrast restored directional selectivity. Under picrotoxin,directional selectivity was lost in 33% of the cells regardless of contrast. However, 47% maintained their preferred direction despite saturating concentrations of picrotoxin, and 20% reversed the preferred and null directions. Therefore, models based solely on a GABAergic implementation of Barrow and Levick's asymmetric-inhibition model or solelyon a cholinergic implementation of asymmetric-excitation models are not complete models of directional selectivity in the rabbit. We propose an alternate model for this retinal property.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/07/20 alle ore 19:43:44