Enhancement of signal-to-noise ratio and phase locking for small inputs by a low-threshold outward current in auditory neurons

Gytis Svirskis, Vibhakar Kotak, Dan H. Sanes, John Rinzel

Research output: Contribution to journalArticle

Abstract

Neurons possess multiple voltage-dependent conductances specific for their function. To investigate how low-threshold outward currents improve the detection of small signals in a noisy background, we recorded from gerbil medial superior olivary (MSO) neurons in vitro. MSO neurons responded phasically, with a single spike to a step current injection. When bathed in dendrotoxin (DTX), most cells switched to tonic firing, suggesting that low-threshold potassium currents (/KLT) participated in shaping these phasic responses. Neurons were stimulated with a computer-generated steady barrage of random inputs, mimicking weak synaptic conductance transients (the "noise"), together with a larger but still subthreshold postsynaptic conductance, EPSG (the "signal"). DTX reduced the signal-to-noise ratio (SNR), defined as the ratio of probability to fire in response to the EPSG and the probability to fire spontaneously in response to noise. The reduction was mainly attributable to the increase of spontaneous firing in DTX. The spike-triggered reverse correlation indicated that, for spike generation, the neuron with /KLT required faster inward current transients. This narrow temporal integration window contributed to superior phase locking of firing to periodic stimuli before application of DTX. A computer model including Hodgkin-Huxley type conductances for spike generation and for /KLT (Rathouz and Trussell, 1998) showed similar response statistics. The dynamic low-threshold outward current increased SNR and the temporal precision of integration of weak subthreshold signals in auditory neurons by suppressing false positives.

Original languageEnglish (US)
Pages (from-to)11019-11025
Number of pages7
JournalJournal of Neuroscience
Volume22
Issue number24
StatePublished - Dec 15 2002

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Keywords

  • Computer model
  • Medial superior olive
  • Phase locking
  • Potassium conductance
  • Signal-to-noise ratio
  • Slice recordings

ASJC Scopus subject areas

  • Neuroscience(all)

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