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SUMMARY:Relating the diversity of firing rates to the dimension of variabi
 lity in recurrent networks - Brent Doiron\, University of Chicago
DTSTART:20241203T140000Z
DTEND:20241203T153000Z
UID:TALK225193@talks.cam.ac.uk
DESCRIPTION:Populations of neurons produce activity with two central featu
 res. First\, neuronal responses are very diverse -- specific stimuli or be
 haviors prompt some neurons to emit many action potentials\, while other n
 eurons remain relatively silent. Second\, the trial-to-trial fluctuations 
 of neuronal response occupy a low dimensional space\, owing to significant
  correlations between the activity of neurons. These two features define t
 he quality of neuronal representation.  We link these two aspects of popu
 lation response using a randomly coupled recurrent circuit model and deriv
 e the following relation: the more diverse the firing rates of neurons in 
 a population\, the lower the effective dimension of population trial-to-tr
 ial covariability. We tested our prediction using simultaneously recorded 
 neuronal populations from numerous brain areas in mice\, non-human primate
 s\, and in the motor cortex of human participants. Surprisingly\, when pop
 ulations are restricted to a single brain area our result holds\, however 
 when a population is composed from neurons spanning multiple brain areas t
 he relation breaks down. This suggests that between brain-area coupling is
  more structured than the local wiring within a brain-area.  Finally\, us
 ing our relation we present a theory where a more diverse neuronal code le
 ads to better fine discrimination performance from population activity. In
  line with this theory\, we show that neuronal populations across the brai
 n exhibit both more diverse mean responses and lower-dimensional fluctuati
 ons when the brain is in more heightened states of information processing.
  In sum\, we present a key organizational principle of neuronal population
  response that is widely observed across the nervous system and acts to sy
 nergistically improve population representation.
LOCATION:CBL Seminar Room\, Engineering Department\, 4th floor Baker build
 ing
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