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SUMMARY:Coding with envelopes\, receptive fields and plasticity - André L
 ongtin\, University of Ottawa
DTSTART:20090325T170000Z
DTEND:20090325T180000Z
UID:TALK17518@talks.cam.ac.uk
CONTACT:Dr Jean-Pascal Pfister
DESCRIPTION:Sensory information processing relies on the proper representa
 tion of scales of space and time  of stimuli into the neural activity. We 
 report on new insights into the organization of this representation\, obta
 ined from our extensive study of hte electric sense. This sense combines a
 spects of the senses of touch\, vision and audition. We first present resu
 lts on circuitry that enables a neural system to represent/extract the slo
 w envelope waveforms that appear in carriers modulated by a narrowband inp
 ut. The circuitry relies on noiseless near-threshold operation followed by
  a slow synapse. Noise can gate this envelope extraction. We then show how
  synchronous input is preferentially decoded by cells that have a large re
 ceptive field. And finally we present results on the possible role of shor
 t-term plasticity in coding in these contexts. We show that for stationary
  noisy signals conveyed through a population of dynamic synapses\, there i
 s\, paradoxically\, no preferential filtering\, regardless of the mixture 
 of facilitation and depression.
LOCATION:Cambridge University Engineering Department\, CBL Rm #438 (http:/
 /www.gatsby.ucl.ac.uk/~lmate/cbl/cbldirections.html)
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