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TZID:Europe/Paris
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UID:1-177@lptms.universite-paris-saclay.fr
DTSTART:20131122T140000Z
DTEND:20131122T150000Z
DTSTAMP:20131105T134320Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-pascal-martin/
SUMMARY:Physics-Biology interface seminar: Pascal Martin - Amphi BLANDIN du
  LPS de la Faculté des Sciences d’Orsay (Bâtiment 510) - 22 Nov 13 14:
 00
DESCRIPTION:The hair-cell bundle as a mechanosensor and amplifier for heari
 ng\nPascal Martin (Institut Curie - Paris)\nThe ear works as a remarkable 
 sound detector.  Hearing can indeed operate over six orders of magnitudes 
 of sound-pressure levels\, with exquisite sensitivity and sharp frequency 
 selectivity to weak sound stimuli.  Curiously\, the ear does not work as a
  high-fidelity sound receiver\, introducing in the auditory percept “pha
 ntom” tones that are not present in the sound input.  In this talk\, I w
 ill present micromechanical experiments at the level of the cellular micro
 phone of the inner ear – the hair cell – whose function is to transduc
 e sound-evoked vibrations into electrical nervous signals.  In particular\
 , I will show that hair cells can power spontaneous oscillations of their 
 mechanoreceptive hair bundles\, a tuft of cylindrical protrusions that pro
 trudes from the apical surface of each cell.  The oscillatory instability 
 is thought to result from a dynamical interplay between ion channels\, ela
 stic proteinous linkages and active molecular motors.  We find that oscill
 ations of the hair bundle allow the hair cell to actively resonate with it
 s mechanical input at the expense of distortions with properties that are 
 characteristic of hearing.  I will conclude by arguing that our results pr
 omote a general principle of sound detection that is based on nonlinear am
 plification by self-sustained “critical” oscillators in the inner ear\
 , i.e. active dynamical systems that operate on the brink of a Hopf bifurc
 ation.\n
LOCATION:Amphi BLANDIN du LPS de la Faculté des Sciences d’Orsay (Bâtim
 ent 510)\, 15 Rue Georges Clemenceau\, orsay\, France
GEO:48.698187;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=Amphi BLANDIN du LPS de la Facu
 lté des Sciences d’Orsay (Bâtiment 510):geo:48.698187,2.181768
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