"Physics of the auditory system" by Dolores Bozovic (University of California, Los Angeles)

Thursday, February 8, 2018 - 4:00pm to 5:00pm
Physics and Astronomy Colloquium

Thursdays, 4:00-5:00 pm

1-434 Physics and Astronomy (map)
Reception from 3:30-4:00 p.m.
(unless otherwise posted)

Guest Speaker: Dolores Bozovic (University of California, Los Angeles)

Talk Title:  “Physics of the auditory system”



The inner ear constitutes a remarkable biological sensor that exhibits nanometer-scale sensitivity of mechanical detection. The first step in auditory processing is performed by hair cells, which act as transducers that convert minute mechanical vibrations into electrical signals that can be sent to the brain. This conversion involves the opening of ion channels, which are mechanically gated. The hair cells operate in a viscous environment, but can nevertheless sustain oscillations, amplify incoming signals, and even exhibit spontaneous motility. The thermodynamic requirements of this indicate the presence of an underlying active process that pumps energy into the system. Theoretical models have proposed that a hair cell constitutes a nonlinear system, and allow us to describe and predict how they respond to incoming sound.


Our experiments explore the physical mechanisms behind the detection of very weak signals, and describe them using models based on dynamical systems theory. We explore the different bifurcations that characterize hair bundle activity, and study how they affect phase-locking to incoming signals. We demonstrate experimentally that bundles can phase-lock to a broad range of frequencies, in various mode-locking ratios. Further, we demonstrate the presence of chaos in the underlying dynamics of active bundles, and explore its impact on the sensitivity of detection. Secondly, we explore the interaction between active bundle mechanics and the electrical circuit comprised of somatic ion channels. Finally, we study the fluctuation dynamics of actively oscillating hair bundles.

For more information, contact Jay Hauser

We thank the following people for their contributions to the wine fund for the post-colloquium reception:
Prof. Dolores Bozovic, Prof. Robijn Bruinsma, Prof. Wesley Campbell, Prof. Bob Cousins, Prof. Jay Hauser, Prof. Eric Hudson, Robert Huff, Prof. HongWen Jiang, Prof. Alex Kusenko, Prof. John Miao, Prof. George Morales, Prof. Pietro Musumeci, Prof. Christoph Niemann, Prof. Rene Ong, Prof. James Rosenzweig, Prof. David Saltzberg, and Prof. Jean Turner.

1-434 PAB