Afferent data rates

Larry Hunter hunter at work.nlm.nih.gov
Wed Aug 14 10:51:52 EST 1991

I asked:

  > I want to find an empirically justified estimate of the amount of
  > afferent (sensory, including visceral) information that human brains
  > are faced with.  

To which Konrad Weigl responded:

  At which level?

  As far as I understand, the biggest task of the whole sensory input
  system is to code the incoming data flow in such a way as to reduce
  bitrate maximally at each step, while keeping relevant information:

  For how that could be done, see e.g. Ralph Linsker's papers on
  models of cell layers in the visual cortex.

  So your question becomes really only meaningful if you state the
  level you refer to, e.g. in the visula processing pathway:

  The retina layer?  The nerve cells in the ocular nerve?  Cortex?
  Which layer there?

I absolutely agree that the biggest task of the whole sensory input
system (in fact, I would go so far as to say, one of the most
important tasks of the entire central nervous system) is to encode
incoming data flow in such a way to reduce the bit rate maximally at
each step, although I would add "without loss of (potentially)
relevant information."  What motivates my question is an attempt to
characterize, in terms of information processing, the magnitude of
that task.  So, let me try to rephrase it:

I am interested in finding an empirically justified estimate of the
rate of information flow into the nervous system.  One way of
estimating this might be to estimate the information content of the
output of all sensory neurons.  This approach is likely to overlook
factors related to phenomena like hyperacuity, but would be an
adequate lower bound on the maximum rate.



Lawrence Hunter, PhD.
National Library of Medicine
Bldg. 38A, MS-54
Bethesda. MD 20894
(301) 496-9300
(301) 496-0673 (fax)
hunter at nlm.nih.gov (internet)

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