Biological Cybernetics

, Volume 89, Issue 5, pp 333–340

Subthreshold outward currents enhance temporal integration in auditory neurons

Article

DOI: 10.1007/s00422-003-0438-2

Cite this article as:
Svirskis, G., Dodla, R. & Rinzel, J. Biol. Cybern. (2003) 89: 333. doi:10.1007/s00422-003-0438-2

Abstract.

Many auditory neurons possess low-threshold potassium currents (IKLT) that enhance their responsiveness to rapid and coincident inputs. We present recordings from gerbil medial superior olivary (MSO) neurons in vitro and modeling results that illustrate how IKLT improves the detection of brief signals, of weak signals in noise, and of the coincidence of signals (as needed for sound localization). We quantify the enhancing effect of IKLT on temporal processing with several measures: signal-to-noise ratio (SNR), reverse correlation or spike-triggered averaging of input currents, and interaural time difference (ITD) tuning curves. To characterize how IKLT, which activates below spike threshold, influences a neuron’s voltage rise toward threshold, i.e., how it filters the inputs, we focus first on the response to weak and noisy signals. Cells and models 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”). Reduction of IKLT decreased the SNR, mainly due to an increase in spontaneous firing (more “false positive”). The spike-triggered reverse correlation indicated that IKLT shortened the integration time for spike generation. IKLT also heightened the model’s timing selectivity for coincidence detection of simulated binaural inputs. Further, ITD tuning is shifted in favor of a slope code rather than a place code by precise and rapid inhibition onto MSO cells (Brand et al. 2002). In several ways, low-threshold outward currents are seen to shape integration of weak and strong signals in auditory neurons.

Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  1. 1.Center for Neural ScienceNew York UniversityNew YorkUSA
  2. 2.Laboratory of NeurophysiologyBiomedical Research Institute, Kaunas Medical UniversityKaunasLithuania
  3. 3.Courant Institute of Mathematical SciencesNew York UniversityNew YorkUSA

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