Analysis of the cellular mechanisms promoting fast information transfer at a large synapse in the ventral nucleus of the lateral lemniscus

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This proposal aims to elucidate the synaptic physiology and the biophysics of information transfer in an ultrafast auditory circuit that is implicated in speech recognition. The ventral nucleus of the lateral lemniscus (VNLL) is tuned to high intensity onsets of broadband stimuli and is thought to prime neurons in the inferior colliculus for the arrival of important sound information. Our investigations try to understand how this circuitry generates a temporally precise inversion from excitation to inhibition on the level of VNLL. We use acute brain slices of Mongolian gerbils to perform single and dual whole-cell recordings from visually identified pre- and postsynaptic compartments in the VNLL, paired with efferent fiber stimulations. We will determine the properties and types of presynaptic calcium channels, transmitter release and the implication of the synaptic strength on the postsynaptic action potentials generation. Postsynaptically we focus on elucidating the molecular identity of voltage gated potassium channels and their interplay with excitatory synaptic currents. These data will be compared to recordings at the well known calyx of Held synapse in the medial nucleus of the trapezoid body. From this comparative, biophysical analysis of the synaptic information transfer we seek to understand the general mechanisms underlying the maintenance of temporal precision produced by large auditory synapses.