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SUMMARY:Dale’s principle and the neural processing of latent factors - A
 lberto Bernacchia\, Jacobs University\, Bremen
DTSTART:20151012T103000Z
DTEND:20151012T113000Z
UID:TALK61440@talks.cam.ac.uk
CONTACT:Guillaume Hennequin
DESCRIPTION:The majority of cortical neurons have an exclusive physiologic
 al effect\, each neuron either excites or inhibits all its synaptic target
 s. This empirical observation\, known as Dale's principle\, poses a strong
  constraint on the structure and computation of neural circuits\, but its 
 function remains unclear.  Proposed explanations include: balancing of neu
 ral activity\, generating oscillations\, accelerating and/or amplifying re
 sponses to stimuli\; However\, Dale's principle is not necessary for imple
 menting any of these functions. A seemingly unrelated\, but influential th
 eory\, posits that neural circuits aim at decomposing input stimuli into a
  set of uncorrelated variables\, called latent factors. Here I propose tha
 t neural circuits aim at transmitting\, rather than reconstructing\, those
  latent factors. I show that Dale's principle is necessary and sufficient 
 for transmitting latent factors\, and that known instances of synaptic pla
 sticity rules (STDP) are consistent with its implementation. I study a dyn
 amical model of a neural circuit characterized by a given synaptic matrix 
 and input covariance matrix. I show that the latent factors of the input c
 ovariance can be transmitted by the neural circuit provided that the synap
 tic matrix satisfies a set of constraints. I show that for most types of i
 nputs\, those constraints tend to enforce Dale's principle. Conversely\, I
  show that enforcing Dale's principle in the synaptic matrix tends to sati
 sfy those constraints. I construct a synaptic plasticity rule that impleme
 nts these constraints and I show that is consistent with STDP. These resul
 ts suggest a novel organizational principle of neural circuits that will h
 elp predicting their behavior. Future work will be devoted to studying how
  the latent factors are transmitted in order to solve specific tasks.
LOCATION:Cambridge University Engineering Department\, CBL\, BE-438 (http:
 //learning.eng.cam.ac.uk/Public/Directions)
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