Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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BCCN AG-Seminar

Tuesday, 06.12.2005 16 c.t.

Looking at both ends of auditory signalling: tireless hair cells and a sloppy and yet precise auditory cortex

by Dr. Claudius Griesinger
from Department of Physiology II, University of Freiburg

Location

Seminarraum Haus 2, 4. Stock (Bunsenstr.)

Abstract

The hallmarks of hearing are exquisite temporal precision, vast dynamic range and literal indefatigability which together enable the consistently precise representation of the auditory environment throughout life. Auditory signalling begins in the cochlea which decomposes complex sounds in narrow frequency bands. These are encoded by synaptic release from inner hair cells operating with unsurpassed temporal accuracy. Temporal precision is maintained during further auditory signalling up to the level of cortical processing and allows the truthful mapping and re-composition of sounds as neural representations. Notwithstanding its fast coding of sound onsets, processing in the auditory cortex however also shows sluggish integrative properties (e.g. the masking phenomenon), posing the “resolution-integration paradox”. The talk examines signalling mechanisms at both ends of the auditory system. Two-photon imaging of vesicle dynamics at individual release sites in inner hair cells in situ shows that they rely on a large cytoplasmic pool of preformed vesicles that swiftly replenish release sites and thus enable fast and sustained synaptic signalling (Griesinger et al., Nature, 2005). Patch-clamp studies of thalamocortical transmission try to shed light on the question why AC is precise and sloppy at the same time.

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