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Titolo:
Firing properties of chopper and delay neurons in the lateral superior olive of the rat
Autore:
Adam, TJ; Schwarz, DWF; Finlayson, PG;
Indirizzi:
Univ,British Columbia, Dept Surg, Rotary Hearing Ctr, Vancouver, BC V6T 2B5 Univ British Columbia Vancouver BC Canada V6T 2B5 , Vancouver, BC V6T 2B5
Titolo Testata:
EXPERIMENTAL BRAIN RESEARCH
fascicolo: 4, volume: 124, anno: 1999,
pagine: 489 - 502
SICI:
0014-4819(199902)124:4<489:FPOCAD>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
ANTEROVENTRAL COCHLEAR NUCLEUS; MOUSE-BRAIN SLICE; INTERAURAL INTENSITY DIFFERENCES; UNIT EXCITATORY RESPONSES; SINGLE AUDITORY UNITS; BINAURAL TONE BURSTS; GUINEA-PIG COCHLEA; D-ASPARTIC ACID; HORSERADISH-PEROXIDASE; OLIVOCOCHLEAR NEURONS;
Keywords:
regularity; lateral superior olive; chopper; lateral olivocochlear system;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
71
Recensione:
Indirizzi per estratti:
Indirizzo: Adam, TJ Univ211itish Columbia, Dept Surg, Rotary Hearing Ctr, Koerner Pavil,F-153,2 Univ British Columbia Koerner Pavil,F-153,2211 Wesbrook Mall Vancouver BC Canada V6T 2B5
Citazione:
T.J. Adam et al., "Firing properties of chopper and delay neurons in the lateral superior olive of the rat", EXP BRAIN R, 124(4), 1999, pp. 489-502

Abstract

Neurons in the lateral superior olivary nucleus (LSO) respond to acoustic stimuli with the "chopper response", a regular repetitive firing pattern with a short and precise latency. In the past, this pattern has been attributed to dendritic integration of synaptic inputs. We investigated a possible contribution of intrinsic membrane properties using intracellular recordingtechniques in a tissue slice preparation. We found two electrophysiological classes of neurons in the LSO. Chopper neurons responded to depolarizing current pulses with a single onset spike at short, precise latency close tothreshold and with repetitive, regular but accommodating discharges at greater current intensities. An emphasis of response onset and subsequent rateaccommodation resulted from the activation of a voltage- and time-dependent sustained outward rectification in a range depolarized from rest. Responses to hyperpolarizing pulses were characterized by an inward rectification,which caused a depolarizing voltage sag in a range negative to -65 mV. Peristimulus time histograms were multimodal, and discharge regularity was evident in narrow unimodal interspike interval time histograms and low coefficients of variation. The accommodation time course was usually fit best by two exponentials with time constants of tau(1)=3-8 ms and tau(2)=32-97 ms. Delay neurons responded with a regular repetitive firing to depolarization by current pulses. However, repetitive spike discharge occurred with a prolonged, variable delay of 25-180 ms. High current intensities evoked an additional onset spike with short, precise latency. Activation of a transient outward conductance in the depolarized voltage range caused an early repolarization, which terminated as a depolarizing ramp, reaching spike threshold after the delay. Flat peristimulus time histograms characterized the repetitive discharge in spite of narrow unimodal interspike interval time histograms and low coefficients of variation. Intracellular neurobiotin injections revealed morphological differences between these classes. Chopper neurons were large and fusiform, with a bipolar dendritic distribution oriented perpendicular to the curvature of the LSO. Delay neurons were small and spherical, with highly branched tortuous dendritic arbours of bipolar origin and variable orientation. Chopper and delay neurons are probably LSO principal cells and lateral olivocochlear efferent neurons, respectively. Our findingssuggest that the pattern of firing activity of LSO neurons to sound, in vivo, is determined to a large extent by intrinsic membrane properties. Somato-dendritic integration of synaptic inputs are fundamental to the encoding of interaural sound differences, but membrane non-linearities play an important role in determining postsynaptic response patterns.

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Documento generato il 05/12/20 alle ore 06:25:29