Toggle Main Menu Toggle Search

Open Access padlockePrints

Classification of frequency response areas in the inferior colliculus reveals continua not discrete classes

Lookup NU author(s): Professor Adrian ReesORCiD



This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


The differential response to sound frequency is a fundamental property of auditory neurons. Frequency analysis in the cochlea gives rise to V-shaped tuning functions in auditory nerve fibres, but by the level of the inferior colliculus (IC), the midbrain nucleus of the auditory pathway, neuronal receptive fields display diverse shapes that reflect the interplay of excitation and inhibition. The origin and nature of these frequency receptive field types is still open to question. One proposed hypothesis is that the frequency response class of any given neuron in the IC is predominantly inherited from one of three major afferent pathways projecting to the IC, giving rise to three distinct receptive field classes. Here, we applied subjective classification, principal component analysis, cluster analysis, and other objective statistical measures, to a large population (2826) of frequency response areas from single neurons recorded in the IC of the anaesthetised guinea pig. Subjectively, we recognised seven frequency response classes (V-shaped, non-monotonic Vs, narrow, closed, tilt down, tilt up and double-peaked), that were represented at all frequencies. We could identify similar classes using our objective classification tools. Importantly, however, many neurons exhibited properties intermediate between these classes, and none of the objective methods used here showed evidence of discrete response classes. Thus receptive field shapes in the IC form continua rather than discrete classes, a finding consistent with the integration of afferent inputs in the generation of frequency response areas. The frequency disposition of inhibition in the response areas of some neurons suggests that across-frequency inputs originating at or below the level of the IC are involved in their generation.

Publication metadata

Author(s): Palmer AR, Shackleton TM, Sumner CJ, Zobay O, Rees A

Publication type: Article

Publication status: Published

Journal: Journal of Physiology

Year: 2013

Volume: 591

Issue: 16

Pages: 4003-4025

Print publication date: 01/08/2013

Online publication date: 12/07/2013

Date deposited: 24/03/2016

ISSN (print): 0022-3751

ISSN (electronic): 1469-7793

Publisher: The Physiological Society


DOI: 10.1113/jphysiol.2013.255943


Altmetrics provided by Altmetric