The effect of sound intensity on duration-tuning characteristics of bat inferior collicular neurons

J Comp Physiol A. 2001 Feb;187(1):63-73. doi: 10.1007/s003590000179.


Previous studies have shown that inferior collicular neurons of the big brown bat, Eptesicus fuscus, serve as short-, band-, long- and all-pass filters for sound durations. Neurons with band-, short- and long-pass filtering characteristics discharged maximally to a specific sound duration or a range of sound durations. In contrast, neurons with all-pass filtering characteristics do not have duration selectivity. To determine if duration-tuning characteristics of collicular neurons were tolerant to changes in sound intensity, we examined the duration-tuning characteristics of collicular neurons using a wide range of sound intensities. Duration-tuning characteristics examined included the type, bandwidth and slope of duration-tuning curves. Sound intensity delivered within 20 dB of minimum threshold did not affect duration-tuning characteristics of all collicular neurons studied. Sound intensities at still higher levels did not affect the tuning characteristics of two-thirds of collicular neurons but decreased the duration selectivity and changed the duration-tuning curves of the remaining one-third of neurons from one type to another. However, these two groups of duration-tuning collicular neurons were not separately organized inside the inferior colliculus. The biological relevance of these findings to bat echolocation is discussed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acoustic Stimulation
  • Action Potentials / physiology
  • Animals
  • Chiroptera / physiology*
  • Echolocation / physiology*
  • Electrodes, Implanted
  • Inferior Colliculi / cytology
  • Inferior Colliculi / physiology*
  • Neurons / physiology*