Temporal sound processing by cochlear nucleus octopus neurons

  • Authors:
  • Werner Hemmert;Marcus Holmberg;Ulrich Ramacher

  • Affiliations:
  • Infineon Technologies Inc., Corporate Research ST, Munich, Germany;Infineon Technologies Inc., Corporate Research ST, Munich, Germany;Infineon Technologies Inc., Corporate Research ST, Munich, Germany

  • Venue:
  • ICANN'05 Proceedings of the 15th international conference on Artificial Neural Networks: biological Inspirations - Volume Part I
  • Year:
  • 2005

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Abstract

The human auditory system excels in the detection of signals in background noise. We evaluate the principles of robust processing with a detailed inner ear model and a model of octopus neurons in the cochlear nucleus. These neurons reject steady-state excitation and fire on signal onsets with extremely high temporal precision. Spike-triggered reverse-correlation analysis revealed that octopus neurons fire preferentially if many coincident spikes follow a short interval of relative low excitation. The frequency spectrum of the reverse-correlation revealed that octopus neurons perform a band-pass analysis of the incoming signal, with the pass-band ranging from about 110 to 650 Hz. The low-frequency slope was approximately 6 dB/oct, which indicates that octopus neurons process the first derivative of the input signal. This mechanism not only removes steady-state activity, which accentuates onsets, but also enhances amplitude modulation in the frequency region predominant in speech.