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Questions about response times to auditory/visual stimuli

Didier A. Depireux didier at Glue.umd.edu
Thu Feb 11 10:56:14 EST 1999


Michael Edelman (mje at mich.com) wrote:

: > propagates up the cochlea (2-3 ms) and a transduction in the inner hair cells, which
: > takes a ms or so.

: Of course the hair cells in the cochlea also have to build up enough transmitter at a
: synapse to initiate an AP. There's no real difference in transduction speed. And when

What you mention has nothing to do with the long latency of retinal cells.
In the retina, light is transduced into electrical activity by first a
gradual polarization that sets up a reaction involving a second messenger
system. You therefore have tens of msecs between light activation and the
generation of an action potential. In the auditory system, the inner hair
cells are active receptors:  a depolarization of the inner hair cells
(caused by the cilia bending) also starts up the transduction process. But
in part because of active processes, and other things I don't want to get
into, the latency for an action potential in the auditory nerve is much
lower, just a couple of msecs.

But don't take my word for it, look up Kandel and Schwartz. For latencies
in the cochlea and AN, look up 'The Cochlea', edited by Dallos, Popper and
Fay. It's about 500 pages long, though.

I hope someone from vision can explain why latencies are so large in
retinal cells better than I did.

						Didier
--
Didier A Depireux                              didier at isr.umd.edu
Neural Systems Lab                 http://www.isr.umd.edu/~didier
Institute for Systems Research          Phone: 301-405-6557 (off)
University of Maryland                                -6596 (lab)
College Park MD 20742 USA                     Fax: 1-301-314-9920



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