[Comp-neuro] inverts and verts

[james bower]

The question has come up in this discussion, whether invertebrates  
with relatively small numbers of neurons, use a fundamentally  
different computational strategy than vertebrates with very large  
numbers of neurons.

This, of course, is a very old debate.

Again, one needs to look at the derivative of the curves.  It was not  
that long ago that most neurobiologists believed that while  
invertebrate neurons had complex sets of channels, vertebrate neurons  
were overall simpler.  It was largely (although not only) the work of  
Sugimori and Llinas on the cerebellar Purkinje cell (in the 70s) that  
made it clear that this was not the case -- vertebrate neurons could  
be as electrically complex as invertebrate neurons -- thus what was  
really a "hope" for simplicity disappeared.   My guess is that the  
more we develop tools to ask the same kinds of questions it is  
relatively (only relatively) easy to ask in invertebrates, we will  
find similar results in vertebrates.

I am reminded of the early days of concurrent (or parallel)  
computing.  There were two conflicting approaches, one, represented  
best by the Boston-based company 'Thinking Machines' built computers  
based on large numbers of simple (bit slice) processors, claiming that  
this was like the mammalian brain.  The other approach, which I was  
involved with at Caltech and JPL, built computers with smaller numbers  
of more sophisticated CPUs.  Of course, at the time, I claimed that  
thinking machines claim that the mammalian brain was made up of a  
large number of relatively simple processors was completely wrong,  
although, in reality the whole argument was really fueled by politics  
and economics not any real interest in the brain.  (ie selling stuff  
to the Pentagon)

Anyway, now, 20 years later -- thinking machines doesn't exist, and  
modern parallel supercomputers use state of the art CPUs.


Jim




==================================

Dr. James M. Bower Ph.D.

Professor of Computational Neuroscience

Research Imaging Center
University of Texas Health Science Center -
-  San Antonio
8403 Floyd Curl Drive
San Antonio Texas  78284-6240

Main Number:  210- 567-8100
Fax: 210 567-8152
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