Molecular and physiological differences underlying temporal and rate coding in auditory brainstem neurons

• Applicant: Professor Dr. Felix Felmy
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 576561557

Sensory information is coded by different strategies including temporal and rate code principles. In the auditory brainstem, both coding strategies occur and are predominant in different nuclei. In the medial nucleus of the trapezoid body (MNTB) temporal coding and in the dorsal nucleus of the lateral lemniscus (DNLL) rate coding dominates. Neurons in these nuclei are cellularly adapted for their different coding and processing tasks. In the MNTB, the fast relay of temporal precise information is guaranteed by the large calyx of held synapse and the biophysical properties that allow onset firing. In the DNLL rate coding is based on small synaptic inputs and membrane properties tuned for sustained firing behavior to support complex, temporally extended integration processes. Despite the strong differences in coding strategies and the biophysical responsiveness, both neurons appear to express a similar set of potassium channels. While apparently in both type of neurons similar potassium channels are present, little is known about the role of specific sodium or other current types. This proposal will first investigate the presence and functional role of one in the DNLL unexpected potassium current, the low voltage-activated DTX-sensitive current, whose function has been detailed in the MNTB and linked to temporally precise, onset action potential behavior. Thereby verifying the similarities in the potassium channel types between these cell populations. These experiments will be followed by comparatively investigating the sodium current types in the MNTB and DNLL. From this combined data we will gain deep understanding of the molecular differences in action potential generation between these two nuclei. To molecularly complement the physiological experiments we will use our recently established patch-seq transcriptome analysis to uncover additional differences in the ion channel composition between the MNTB and the DNLL. Therefore, this proposal will disentangle the molecular and physiological differences that endow neurons with specific adaptations to serve different coding strategies.

• DFG Programme: Research Grants