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Intercollicular commissural projections modulate neuronal responses in the inferior colliculus

Lookup NU author(s): Professor Adrian ReesORCiD


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The right and left inferior colliculi (ICs) in the auditory midbrain are connected to one another by a bundle of fibres, the commissure of the IC. Previous studies show that this commissural projection connects corresponding frequency regions in the two sides and originates mainly from excitatory neurons, although some studies suggest a smaller number of GABAergic inhibitory neurons may also project via the commissure. Although the commissure of the IC is a major pathway connecting the most important nuclei of the auditory tectum, little is known about its functional significance. To investigate its role in auditory processing in the rat, we recorded sound-evoked responses of single neurons in one IC while injecting kynurenic acid into a corresponding region of the opposite IC. This procedure enabled us to block reversibly excitation of commissural projections to the recorded IC. The changes in the neural responses when input from the opposite IC was blocked are consistent with the commissural projection exerting both an excitatory and an inhibitory influence. The inhibition could be accounted for by monosynaptic or disynaptic connections. The responses to both monaural and binaural stimulation were affected, and the effects were proportionately greater at near-threshold sound levels. The results suggest that one function of the commissure of the IC may be to modulate the response gain of IC neurons to acoustic stimulation. © 2005 Federation of European Neuroscience Societies.

Publication metadata

Author(s): Malmierca MS, Hernandez O, Rees A

Publication type: Article

Publication status: Published

Journal: European Journal of Neuroscience

Year: 2005

Volume: 21

Issue: 10

Pages: 2701-2710

ISSN (print): 0953-816X

ISSN (electronic): 1460-9568

Publisher: Wiley-Blackwell Publishing Ltd.


DOI: 10.1111/j.1460-9568.2005.04103.x

PubMed id: 15926918


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