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Titolo:
GABA INPUTS CONTROL DISCHARGE RATE PRIMARILY WITHIN FREQUENCY RECEPTIVE-FIELDS OF INFERIOR COLLICULUS NEURONS
Autore:
PALOMBI PS; CASPARY DM;
Indirizzi:
SO ILLINOIS UNIV,SCH MED,DEPT PHARMACOL,801 N RUTLEDGE SPRINGFIELD IL62702
Titolo Testata:
Journal of neurophysiology
fascicolo: 6, volume: 75, anno: 1996,
pagine: 2211 - 2219
SICI:
0022-3077(1996)75:6<2211:GICDRP>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
STEM AUDITORY NUCLEI; POSTEROVENTRAL COCHLEAR NUCLEUS; BINAURAL RESPONSE PROPERTIES; GAMMA-AMINOBUTYRIC ACID; MEDIAL GENICULATE-BODY; CENTRAL-NERVOUS-SYSTEM; LATERAL LEMNISCUS; BRAIN-STEM; DORSAL NUCLEUS; GUINEA-PIG;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Physical, Chemical & Earth Sciences
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
89
Recensione:
Indirizzi per estratti:
Citazione:
P.S. Palombi e D.M. Caspary, "GABA INPUTS CONTROL DISCHARGE RATE PRIMARILY WITHIN FREQUENCY RECEPTIVE-FIELDS OF INFERIOR COLLICULUS NEURONS", Journal of neurophysiology, 75(6), 1996, pp. 2211-2219

Abstract

1. Recent studies have suggested that gamma-aminobutyric acid (GABA) inputs shape monaural and binaural neuronal response properties in thecentral nucleus of the inferior colliculus (CIC). CIC neurons receivemajor inhibitory GABAergic projections from intrinsic, commissural, and extrinsic sources. Many GABAergic projections now are thought to arise from cells that are tonotopically matched to their CIC targets. 2. We tested the hypothesis that GABA circuits are aligned primarily within the CIC target neuron's excitatory response area and therefore have their greatest effects on discharge rate mainly within that frequency domain. GABA inhibition was examined by recording families of isointensity contours before, during, and after GABA(A) receptor blockade. Iontophoretic application of bicuculline-methiodide (BMI) was used to block GABA(A) receptors. Quantitative measures of frequency bandwidth and z-score analysis of discharge rate within the excitatory receptive field were used to compare pre- and postdrug conditions 3. Chinchilla CIC unit response properties were similar to those described for otherspecies, with a high percentage of phasic temporal response patterns and nonmonotonic rate-intensity functions in response to monaural contralateral characteristic frequency (CF) tones. Binaural responses of most CIC neurons showed suppression of contralaterally evoked responsesby ipsilateral stimulation. 4. For 85% of CIC neurons, blockade of GABA(A) inputs was found to increase discharge rate within the excitatory response area. Forty-five percent were classified as near-CF changesand 32% as near-CF and low side. Changes in lateral/flanking inhibition in the absence of near-CF changes were never observed. Forty-one percent of CIC neurons displayed less than a 10% increase in frequency bandwidth at 25-35 dB above threshold with BMI application. 5. These data suggest that GABA inhibition arises primarily from neurons with inhibitory fields aligned with their CIC targets. Thus the effect of the inhibition is primarily contained within or overlapping each target neuron's excitatory response area. CIC GABAergic circuits may function to adjust the gain needed for coding complex signals over a wide dynamic range.

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Documento generato il 05/12/20 alle ore 14:02:54