[Comp-neuro] Review announcement

Eric E. Thomson thomson at neuro.duke.edu
Fri Aug 1 17:26:13 CEST 2008


==1. What did the first cortex do?===
Bower has suggested that olfactory processing drove cortical evolution. Is there a review article on this? I know there are many types of paleocortex (e.g., olfactory, some motor cortex is paleo, etc), and had never heard that olfactory processing drove cortical evolution. Is that something established, or  a "viewpoint"? I would have guessed that motor processing was the main engine for cortical evolution, since the brain is an engine for coordinating behavior.  I'd appreciate pointers to any published findings on this. Likely the first cortex was a little bit sensory, a little bit motor.


==2. Oscillations are epiphenomena==
Bower suggested large-scale "oscillations" are epiphenomenal. This inspired me to write a little bit about this at my web site:
http://neurochannels.blogspot.com/2008/07/what-good-is-large-scale-oscillatory.html

Here are the last couple of paragraphs of that post:
My guess is that it will turn out that [oscillations] are important for the functioning of some parts of some systems, but settling which parts of which systems isn't a question that can be resolved a priori. Unfortunately, right now we are stuck mostly with correlation studies, which keeps the ratio of inference to data unacceptably high.

Stepping back from specific data suggesting that oscillations are important, Buzsaki's book Rhythms of the Brain is likely a good place to start to get the theist's side of things with respect to the importance of oscillations. I should admit I haven't read it, but only seen him speak and have read some of his papers, so caveat emptor. I can say his experimental work is wonderful, much of it driven by questions about the function of oscillations in the CNS, so his book seems like a natural place to start for someone interested in this question.


==3. The cortical column does not exist==

A couple of people have mentioned the Horton and Adams paper on the cortical column, and since I work in the whisker barrels of rodents, I have trouble accepting that columns don't exist. I've seen them, and they behave differently from one another in aneshtetized animals. That said, I do think they might not be the "fundamental functional unit" in the cortex. A few months back, I wrote up a blurb on this topic, inspired by a recent paper by Douglas and Martin paper cited below:
http://neurochannels.blogspot.com/2007/12/cortical-computation-some-complications.html

There, I suggest that the "fundamental computational unit" of the cortex might not exist, that the fundamental unit might be the thalamocortical loop (for the back, more sensory-oriented, part of the brain), or the cortico-striatal-thalamic loops (for the front, action-oriented, part of the brain).


Cited
Rodney J. Douglas, and Kevan A.C. Martin (2007) Mapping the Matrix: The Ways of Neocortex Neuron, Vol 56, 226-238, 25 October 2007


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