[Neuroscience] Re: Wherefore art thou Neuron Code?

John H. via neur-sci%40net.bio.net (by bingblat from goaway.com.au)
Tue Apr 3 04:49:52 EST 2007


"Glen M. Sizemore" <gmsizemore2 from yahoo.com> wrote in message
news:4610ed18$0$24160$ed362ca5 from nr2.newsreader.com...
>
> "John H." <bingblat from goaway.com.au> wrote in message
> news:461097d6 from quokka.wn.com.au...
> > It's Only A Game Of Chance: Leading Theory Of Perception Called Into
> > Question
> > Science Daily - The validity of a leading theory that has held a glimmer
> > of
> > hope for unraveling the intricacies of the brain has just been called
into
> > question. Dr. Ilan Lampl of the Weizmann Institute of Science's
> > Neurobiology
> > Department has produced convincing evidence to the contrary. His
findings
> > recently appeared in the journal Neuron.
> >
> > http://www.sciencedaily.com/releases/2007/03/070327144225.htm
> >
> >
> "According to the theory, the brain is able to discriminate between, say,
a
> chair and a table because each of them will generate a distinct sequence
of
> patterns within the neural system that the brain then interprets."
>
>
>
> Let's assume for a moment that chairs and tables are "distinct patterns."
> Then the question becomes "How do the distinct patterns we call 'chair'
and
> 'table' come to produce these different responses?" Notice that the common
> theory is simply that the difference in the patterns are somehow preserved
> in the brain. But how does this explain anything? We now have to explain
how
> the differences in pattern "in the brain" explain the differences in
> response. If this was a legitimate question when the "patterns" were out
in
> the environment, why is it not a legitimate question when the pattern is
"in
> the brain"? I won't comment extensively on the rest of the blurb because
not
> enough information is given about what was done other than to say that
> Skinner always used to say things like "The pattern of stimulation on the
> retina is quickly lost in the nervous system" (this is a paraphrase). I
> began to think that he was just a bit behind the times, and my criticism
of
> representationalism focused on the fact that 1.) "representation" must be
> functionally-defined (i.e. a "mapping is not necessarily a
"representation"
> and 2.), that the presence of "mappings" in the brain does no more to
> explain seeing than patterns in the world. Now it seems that even the
notion
> of a consistent mapping may be bullshit. As I have said many times,
despite
> the arm-breaking self-back-patting of neuroscientists (especially those
that
> are concerned with behavior) we are about at the level where we have a
> more-or-less complete description of habituation of the gill-withdrawal
> reflex in Aplysia. The general point to be made is that, in many, many
cases
> in neuroscience, behavior hasn't been broken down into the right
analytical
> units - that is, the conceptual structure inherited from mainstream
> psychology is, literally, nonsense. Note that, despite Kandel's careless
> language, "habituation" is conceptually clean.
>


This news items interested me because:

A few years ago I read a unpublished meta analysis of fMRI studies that
suggested there is a great deal of contradiction in these studies.

In a paper addressing language processing across the menstrual cycle the
degree of change in cerebral activation is most striking. It don't make no
sense and it can't at present.

You don't have to know much about neuroscience to question the "mapping
hypothesis". It never made sense to me, even when I cruising the streets and
reading next to nofing.

If the best we can do is understand the gill reflex to what extent can we
justify investigating human behavior using the tools currently available?

I was recently introduced to the idea that in the mammalian brain there are
at least 4 "action selection" centres: medial RF, BG, SMA, PFC, and perhaps
the P. fossa for good measure. So much for modularity.

Modularity of a type does exist but only two weeks ago I read an abstract
claiming that in the rat the "barrel whisker" response or whatever you bods
call it is mediated in part by the superior collicus. These nuclei have
typically been associated with vision now we find ... Same is true of
cerebellum, once believed to be involved in fine tuning motor actions, it
now appears to be involved in just about everything. Me thinks this will be
found for many CNS regions.

It's generally getting very spooky. Two weeks ago a news release cited the
claim by some neuros that neurons actually communicate by sound waves! And
two months that quantum tunnelling stuff in relation to olfaction.

Me now very confused, shall stick with neuroimmunology!


John.








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