Journal of Comparative Physiology A

, Volume 196, Issue 12, pp 889–897

Regularly firing neurons in the inferior colliculus have a weak interaural intensity difference sensitivity

Original Paper

DOI: 10.1007/s00359-010-0532-6

Cite this article as:
Nasimi, A. & Rees, A. J Comp Physiol A (2010) 196: 889. doi:10.1007/s00359-010-0532-6


The spike discharge regularity may be important in the processing of information in the auditory pathway. It has already been shown that many cells in the central nucleus of the inferior colliculus fire regularly in response to monaural stimulation by the best frequency tones. The aim of this study was to find how the regularity of units was affected by adding ipsilateral tone, and how interaural intensity difference sensitivity is related to regularity. Single unit recordings were performed from 66 units in the inferior colliculus of the anaesthetized guinea pig in response to the best frequency tone. Regularity of firing was measured by calculating the coefficient of variation as a function of time of a unit’s response. There was a positive correlation between coefficient of variation and interaural intensity difference sensitivity, indicating that highly regular units had very weak and irregular units had strong interaural intensity difference sensitivity responses. Three effects of binaural interaction on the sustained regularity were observed: constant coefficient of variation despite change in rate (66% of the units), negative (20%) and positive (13%) rate–CV relationships. A negative rate-coefficient of variation relationship was the dominant pattern of binaural interaction on the onset regularity.


RegularityInferior colliculusBinauralInteraural intensity difference



Best frequency


Coefficient of variation


Inferior colliculus


Central nucleus of IC


Interaural intensity difference


Interspike interval


Lateral superior olive


Post-stimulus time histogram

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Department of PhysiologyIsfahan University of Medical SciencesIsfahanIran
  2. 2.School of Neurology, Neurobiology, and PsychiatryUniversity of NewcastleNewcastle upon TyneUK