[tt] the physics arXiv blog

[Eugen Leitl]

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From: the physics arXiv blog <howdy at arxivblog.com>
Date: Tue, 8 Apr 2008 17:27:24 -0500 (CDT)
To: eugen at leitl.org
Subject: the physics arXiv blog
Reply-To: the physics arXiv blog <howdy at arxivblog.com>


[1]the physics arXiv blog

   [2]Criticality and the brain

   Posted: 08 Apr 2008 12:24 AM CDT

   [3]Brain connections 

   Our understanding of how various parts of brain function is advancing
   at breakneck speed and yet we are as far away as ever from an
   overarching "theory of the brain" that attempts to encompass these
   discoveries. Such a theory would unite disparate discoveries in brain
   science under a unifying theme.

   Now Dante Chialvo from Northwestern University in Chicago and
   colleagues attempt to do just that. Their proposal is that the brain
   is spontaneously posed at the border of a second order phase
   transition, just like the transition a ferromagnetic material
   undergoes as it swtches from a non-magnetic to a magnetic phase.

   One of the features of these transitions is the existence of a
   critical point in which both phases exist simultaneously in a way that
   ensures that the distinction between them more or less disappears. At
   this so called "criticality", all kinds of curious phenonena have been
   found, including self organising behaviour.

   Chialvo and buddies say "all human behaviors, including thoughts,
   undirected or goal oriented actions or any state of mind, are the
   outcome of a dynamical system at or near a critical state."

   They make a list of features that they would expect the brain to
   demonstrate in experiment were it operating close to criticality.

   At large scales, they say, we should see cortical long range
   correlations in space and time as well as large scale anti-correlated
   cortical states. That certainly seems to be true of our brains in
   general.

   And at small scale, we should see "Neuronal avalanches", as the normal
   homeostatic state for most neocortical circuits. And sure enough, the
   group point to evidence for this.

   The trouble is that these look very much like an after-the-fact-
   predictions in this paper, a feeling that is backed up by the absence
   of any testable hypothesis about the brain.

   If the brain is close to crticiallity (which doesn't seem like too far
   fetched an idea), surely it would be possible to make some predictions
   about the results of experiments such as those involving human
   attention, optical illusions and the reaction to various stimuli.

   So while Chialvo's proposal may make the pretense of being a theory of
   the brain, to my mind they'll have to settle for the status of
   "interesting idea" until somebody takes them significantly further.

   Ref: [4]arxiv.org/abs/0804.0032: The Brain: What is Critical about It?

   [5][arXivblog?i=QxMUzn] 
   [6][arXivblog?i=f19GjAG] [7][arXivblog?i=H6Fuo0G]
   [8][arXivblog?i=hwDeNGg] [9][arXivblog?i=L1wfMrG]
   [10][arXivblog?i=ueOVF1g] [11][arXivblog?i=KNvLOyG]
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References

   1. http://arxivblog.com/
   2. http://feeds.feedburner.com/~r/arXivblog/~3/266114331/
   3. http://arxivblog.com/wp-content/uploads/2008/04/brain-connections.jpg
   4. http://arxiv.org/abs/0804.0032
   5. http://feeds.feedburner.com/~a/arXivblog?a=QxMUzn
   6. http://feeds.feedburner.com/~f/arXivblog?a=f19GjAG
   7. http://feeds.feedburner.com/~f/arXivblog?a=H6Fuo0G
   8. http://feeds.feedburner.com/~f/arXivblog?a=hwDeNGg
   9. http://feeds.feedburner.com/~f/arXivblog?a=L1wfMrG
  10. http://feeds.feedburner.com/~f/arXivblog?a=ueOVF1g
  11. http://feeds.feedburner.com/~f/arXivblog?a=KNvLOyG
  12. http://feeds.feedburner.com/~f/arXivblog?a=uGcmsQg
  13. http://feeds.feedburner.com/~f/arXivblog?a=2aRvbOG
  14. http://arxivblog.com/
  15. http://www.feedburner.com/fb/a/emailunsub?id=8632699&key=kesJ612ZsV
  16. http://feeds.feedburner.com/arXivblog
  17. http://feeds.feedburner.com/arXivblog

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Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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