Synaptic modification rules ?

David Longley David at longley.demon.co.uk
Tue May 18 03:47:35 EST 2004


In article 
<m.kirkcaldie-89E94E.12103018052004 at tomahawk.comms.unsw.edu.au>, Matthew 
Kirkcaldie <m.kirkcaldie at removethis.unsw.edu.au> writes
>In article <ec29a509.0405171729.37d57bb5 at posting.google.com>,
> nettron2000 at aol.com wrote:
>
>>  Although this idea doesnt account for depression, how did Hebb guess
>> this concept ?
>
>I suppose he figured, well, activity must change synapses if we are to
>permanently learn something, so he related one to the other.  Presumably
>this was the version of the idea which seemed most likely to be
>realistic.
>
>> I know there are other related concepts to this such as
>> anti-hebbian and what not, but does anyone know of other "rules" ( i
>> use the term loosely) that can account for synaptic modification ?
>
>I kinda thought the several paragraphs I typed answered this question.
>If not, can you explain what you mean by "rule" in this context?  The
>brain isn't a computer.
>
>      Matthew.

I think folk here should look first hand at Hebb's book "Organization of 
Behavior (A Neuropsychological Theory)" and note the date (1949) and 
hold on the speculation. There's far too much of it about. It might also 
be wise to have a look at one of Clark Hull's "A Behavior System" 1952 
(the first volume of which was his "Principles of Behavior" 1943. Hull 
dominated US psychology at that time. Both Hebb (relatively a much more 
minor player), and Hull were S-R psychologists. Methodological 
Behaviorists. They speculated (or used the Hypothetico-Deductive method) 
to posit "intervening variables" or "hypothetical constructs" between 
stimulating conditions (S) and behavior (R). Both posited "conceptual 
neural" systems. Whilst Hull tried to explicate his theory in 
mathematical terms, Hebb tended to neurologise a bit, although his "cell 
assemblies" were really all conceptual. All of this led to the rabid 
"cognitivism" we have seen since the late 1950s as "Cognitive 
Psychology" and then "Cognitive Science".

You would be wise to note the alternatve. Skinner criticised this sort 
of (speculative) work in the 1950s by criticising "mathematical learning 
theory" which is basically what Hull's approach had morphed into by 
then. But he also criticized the speculative "conceptual neurologizing" 
too for reasons that have already been outlined here by myself and 
Sizemore.

The strengths of the good research in neuroscience have always been that 
it has been largely descriptive and driven by the rest of the reliable 
web of scientific knowledge (chemistry, biophysics etc).

This is sadly becoming a serious problem in modern neuroscience, mainly 
through the pernicious influence of "cognitive science". Even Kandel 
seems to go astray when he wildly speculates about that dustbin of 
research, hippocampal plasticity and "memory"!
-- 
David Longley



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