Journal of Comparative Physiology A

, Volume 174, Issue 6, pp 671–683

Frequency tuning and response latencies at three levels in the brainstem of the echolocating bat, Eptesicus fuscus

  • S. Haplea
  • E. Covey
  • J. H. Casseday
Article

DOI: 10.1007/BF00192716

Cite this article as:
Haplea, S., Covey, E. & Casseday, J.H. J Comp Physiol A (1994) 174: 671. doi:10.1007/BF00192716

Abstract

To determine the level at which certain response characteristics originate, we compared monaural auditory responses of neurons in ventral cochlear nucleus, nuclei of lateral lemniscus and inferior colliculus. Characteristics examined were sharpness of frequency tuning, latency variability for individual neurons and range of latencies across neurons.

Exceptionally broad tuning curves were found in the nuclei of the lateral lemniscus, while exceptionally narrow tuning curves were found in the inferior colliculus. Neither specialized tuning characteristic was found in the ventral cochlear nuclei.

All neurons in the columnar division of the ventral nucleus of the lateral lemniscus maintained low variability of latency over a broad range of stimulus conditions. Some neurons in the cochlear nucleus (12%) and some in the inferior colliculus (15%) had low variability in latency but only at best frequency.

Range of latencies across neurons was small in the ventral cochlear nucleus (1.3–5.7 ms), intermediate in the nuclei of the lateral lemniscus (1.7–19.8 ms) and greatest in the inferior colliculus (2.9–42.0 ms).

We conclude that, in the nuclei of the lateral lemniscus and in the inferior colliculus, unique tuning and timing properties are built up from ascending inputs.

Abbreviations

AVCN

anteroventral cochlear nucleus

BF

best frequency

CV

coefficient of variation

DCN

dorsal cochlear nucleus

FM

frequency modulation

IC

inferior colliculus

NLL

nuclei of lateral lemniscus

PSTH

post stimulus time histogram

PVCN

posteroventral cochlear nucleus

SD

standard deviation

SPL

sound pressure level

VCN

ventral cochlear nuclei

VNLLc

ventral nucleus of the lateral lemniscus, columnar division

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • S. Haplea
    • 1
  • E. Covey
    • 1
  • J. H. Casseday
    • 1
  1. 1.Department of NeurobiologyDuke University Medical CenterDurhamUSA