In this thesis, different aspects of central auditory processing in the inferior colliculus (IC) of young-adult mice and rats are described. With the “in vivo patch-clamp” technique we investigated the contribution of membrane properties and synaptic integration of excitatory and inhibitory inputs to sound processing in an intact auditory system. We describe how biocytin cell injections and vesicular glutamate transporter -1 and -2 stainings can be used to confirm localization of measured cells and to identify the central nucleus of the IC. Next, constant current injections were used to characterize the firing patterns and basic membrane properties of IC neurons. New findings include the presence of electrical synapses (spikelets), the absence of onset firing, the absence of a classic pause in buildup neurons and a description of accelerating cells. In addition, spontaneous excitatory synaptic potentials contributed to the irregularity of spike patterns! . The clearest mechanism in duration tuning seems to be synaptic integration of excitatory and inhibitory inputs and synaptic adaptation, while AM tuning seems to be more influenced by the presence of calcium-dependent potassium channels and the absence of adaptation. Hyperpolarization-activated voltage-dependent sodium/potassium channel Ih can additionally shape the incoming auditory signal. FM tuning is largely determined by the synaptic integration of excitatory and inhibitory inputs, while membrane properties and ion-channels play a lesser role. By showing how the diversity in membrane properties and synaptic inputs can lead to specific tuning for complex sounds, we provide a cellular explanation for the contribution of the IC to central auditory processing.

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Publication of this thesis was financially supported by: ALK-Abelló B.V., Artu Biologicals, Atos Medical B.V., Beltone Netherlands B.V., Beter Horen B.V., Carl Zeiss B.V., Daleco Pharma B.V., Decos Systems B.V., EmiD audiologische apparatuur, GlaxoSmithKline, de Nationale Hoorstichting / Sponsor Bingo Loterij, de Nederlandse Vereniging voor KNO-heelkunde en Heelkunde van het Hoofd-Halsgebied, Olympus Nederland B.V., Oticon B.V., Schoonenberg Hoorcomfort, Veenhuis Medical Audio B.V.
L. Feenstra (Louw) , J.G.G. Borst (Gerard)
Erasmus University Rotterdam
Erasmus MC: University Medical Center Rotterdam

Tan, M. L. (2009, September 16). Cellular mechanisms of auditory processing in the inferior colliculus: An in vivo patch clamp study. Retrieved from