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Balanced inhibition and excitation underlies spike firing regularity in ventral cochlear nucleus chopper neurons
Author(s) -
Paolini Antonio G.,
Clarey Janine C.,
Needham Karina,
Clark Graeme M.
Publication year - 2005
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2005.03958.x
Subject(s) - excitatory postsynaptic potential , inhibitory postsynaptic potential , hyperpolarization (physics) , neuroscience , cochlear nucleus , nucleus , electrophysiology , chemistry , stimulus (psychology) , bursting , membrane potential , biophysics , biology , psychology , stereochemistry , nuclear magnetic resonance spectroscopy , psychotherapist
Ventral cochlear nucleus stellate cells respond to characteristic frequency (CF) tones with sustained (C S ), transient (C T ) or onset chopping (O C ) activity. The mechanisms underlying these different response patterns are not fully understood, and the present study used in vivo intracellular recordings ( n = 42) in urethane‐anaesthetized rats to examine the possible influence of inhibition on action potential regularity. Hyperpolarization following the offset of a CF tone burst was used as a measure of on‐CF inhibition. A cluster analysis based on several membrane potential features, including on‐CF inhibition, discriminated three groups in addition to the C S response type − two types of C T responses and the O C type. The different patterns of firing regularity exhibited by C S/T neurons reflected different thresholds or degrees of overlap between these cells' narrowly tuned excitatory and inhibitory inputs. C T cells with closely matched inhibitory and excitatory response areas showed substantial on‐CF inhibition and the greatest decline in firing regularity during a CF tone, whereas those with a mismatch between their response areas showed lateral inhibition and a less marked decline in firing regularity. The presence of inhibition in C S neurons did not alter their firing regularity, possibly because of the lower threshold for excitation compared with inhibition. The latency, duration and frequency extent of sustained hyperpolarization in C S/T cells is inconsistent with the response properties of O C neurons, suggesting that another source(s) of inhibition influences firing regularity, and presumably response magnitude, in these neurons.