Mechanisms and impact of NMDA-receptor signaling during sensory processing in an echo-locating circuit

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The role of NMDA-receptors in neuronal plasticity is well established. However, their role in intracellular voltage-signaling and sensory processing is less well characterized, yet they are implicated in amplifying action potential firing rates. To understand the cellular basis for this NMDA dependent amplification of firing rate, its influence on sensory information processing we will perform in vivo and in vitro recordings of neurons in the dorsal nucleus of the lateral lemniscus (DNLL) - an auditory brainstem structure important for binaural hearing. We will determine the synaptic interactions of excitation and inhibition with NMDA-receptor conductances to understand their contributions to intracellular voltage-signaling in vitro. Using in vivo pharmacology we will answer what impact NMDA receptors have on sound driven firing rates. Thereby, the DNLL serves on the one hand as a read out nucleus where the impact of NMDA-receptors on relaying binaural information will be quantified. On the other hand we will assay in vivo the direct binaural interactions at the level of the DNLL to understand the influence of NMDA-receptors on interactions between inhibition and excitation. We hypothesize that these interactions might be crucial in terminating a long lasting inhibition that is regarded as a cellular correlate for the suppression of sound sources during echoes.