[Neuroscience] Re: Wherefore art thou Neuron Code?
(by r_s_norman from _comcast.net)
Wed Apr 4 07:43:29 EST 2007
On Wed, 4 Apr 2007 07:30:34 -0400, "Glen M. Sizemore"
<gmsizemore2 from yahoo.com> wrote:
>Damn! I wrote a rather long reply to this, and left it slightly unfinished,
>and during the night my computer rebooted and the document was not even in
>backup. Let me reply briefly, and maybe later I'll revisit the issue. The
>modern imaging stuff (a perfect example of how neuroscience obtains new
>facts because of physics and engineering rather than by new
>conceptualizations) is largely a load of crap. I have always criticized it
>on conceptual grounds - even if the findings are accurate, and mean what
>they re purported to mean (i.e., that part of the brain is more active) the
>importance of such findings is dubious. OK, such-and-such a brain area is
>active - how does that explain the physiology of behavioral function.
>Obviously, the fact is of potential importance, but the data are simply used
>to argue a version of what should be called neurophysiological animism.
>"Look Martha! There's where the executive lives!" "And all the file clerks
>have to live in the hippocampus!" Now it appears that there may be little
>reliability in the measurements - oh well, another few decades of pissing
>into the wind.
There is real value in the imaging work, but not as the "explanations"
of behavior that are widely touted. "Aha, when you do X then brain
structure Y lights up. So Y causes X!" That is nonsense. However
it does strongly indicate that some specific neuronal circuits that
are strongly associated with X are located in Y. My main problem with
it is that if you see a 1 mm speck of brain tissue lighting up (and I
am not sure that the resolution is even as good as 1 mm) then there
are still some 1000 to 10,000 neurons possibly involved. You will
never even discover the enormous significance of all those other cells
whose locations are scattered enough so that there is no significant
change in blood patterns and oxygen usage at those locations.
I get even angrier when i hear or read about the "fact" that serotonin
is the "depression chemical" or dopamine the "addiction chemical" or
whatever the current fashion might be. Nobody ever says that acetyl
choline is the "breathing chemical" even though if you block
cholinergic junctions, you quickly die from lack of respiration.
>Modularity has, no doubt some sort of verity, but what are the modules?
>This, of course, is a version of what I mostly argue around here: unless we
>conceptualize behavior properly, we can never explain it at the
>physiological level. We literally do not understand what we are trying to
>explain! Needless to say, I think that behavior analysis has identified the
>core processes, and behaviorists - most notably the Big BF himself - have
>gone far in saying how these core processes interact as complex behavior is
>produced. To say that this view is, ummm, a minority view, is the
>understatement of the century.
I happen to strongly believe in modularity. It is essential when I do
computer programming. It is almost certainly as essential when
evolution (or learning) does brain programming. However the main
point is, as you say, "we literally do not understand what we are
trying to explain"
>"John H." <bingblat from goaway.com.au> wrote in message
>news:46122312 from quokka.wn.com.au...
>> "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
>>> > question. Dr. Ilan Lampl of the Weizmann Institute of Science's
>>> > Neurobiology
>>> > Department has produced convincing evidence to the contrary. His
>>> > 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,
>>> chair and a table because each of them will generate a distinct sequence
>>> 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'
>>> 'table' come to produce these different responses?" Notice that the
>>> theory is simply that the difference in the patterns are somehow
>>> in the brain. But how does this explain anything? We now have to explain
>>> the differences in pattern "in the brain" explain the differences in
>>> response. If this was a legitimate question when the "patterns" were out
>>> the environment, why is it not a legitimate question when the pattern is
>>> the brain"? I won't comment extensively on the rest of the blurb because
>>> 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
>>> representationalism focused on the fact that 1.) "representation" must be
>>> functionally-defined (i.e. a "mapping is not necessarily a
>>> 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
>>> of a consistent mapping may be bullshit. As I have said many times,
>>> the arm-breaking self-back-patting of neuroscientists (especially those
>>> 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
>>> in neuroscience, behavior hasn't been broken down into the right
>>> 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
>> 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
>> at least 4 "action selection" centres: medial RF, BG, SMA, PFC, and
>> 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
>> 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
>> 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!
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