|Synaptic processing in the cochlea and the dynamic range problem|
Jonathan Ashmore (Univ. College London)
8 janvier 2009
Second exposé présenté par Jonathan Ashmore dans le cadre du séminaire complémentaire, Physiologie cochléaire : actualités, du cours 2008–09 de Christine Petit, professeur titulaire de la chaire Génétique et physiologie cellulaire au Collège de France.
The information about the frequency, intensity and timing of sound arriving at ear is encoded by the sensory cells of the cochlea, the inner hair cells. The frequency components in a complex sounds are analysed on a moment-by-moment basis as described in the first lecture, and this information is then relayed to auditory nerve by populations of inner hair cells. Information about the intensity of the sound is carried by the stratified activity of populations of auditory nerve fibres, although there is still dispute about the precise mechanisms: this is known as the dynamic range problem.
In this lecture I shall be discussing new and recent experiments carried out at the Institut Pasteur during tenure of a Chaire Blaise-Pascal which address this latter point. Using imaging methods it has proved possible to identify synaptic activity at the inner hair cells of the mouse and to characterise some of the events occurring during electrical activation of the synapse.
The lecture will be prefaced by a short discussion of some recent results obtained by a group at M.I.T. which visualise the tectorial membrane, a further mechanically active structure within the mammalian cochlea.
|Jonathan Ashmore (Univ. College London)|
Jonathan Ashmore is Bernard Katz Professor of Biophysics au Ear Institute, University College London (UCL School of Life & Medical Sciences).