Working memory

F. Frank LeFever flefever at ix.netcom.com
Thu Mar 19 23:03:15 EST 1998


In <6eosej$kt5$2 at geraldo.cc.utexas.edu> jvalla at mail.utexas.edu (JValla)
writes: 
>
>In article <1998031807310801.CAA15177 at ladder01.news.aol.com>, 
>uwilwantme at aol.com says...
>>
>>Have we forgotten that you cannot completely localize function to ONE
area of
>>the brain? 
>
>Bravo!  It is simplistic and dogmatic to go on shouting that working
memory is 
>a "hippocampal function" or a "prefrontal function" when it is clear
that 
>numerous areas must work together (e.g., the hippocampus AND the
prefrontal 
>cortex, among others).  Learning, "memory," and plasticity take place 
>throughout the nervous system.


See my reply to jvall for a more extended answer.  You do me a
disservice to suggest that I (a researcher in rat and human
neuropsychology for many years) naively "locate" anything anywhere.

It is important, however that not all "nodes in a circuit" are equal,
for all tasks.  As a clinical neuropsychologist (yes, I'm that also) I
could not be able to locate likely LESION sites if lesions in one site
caused the same changes in performance that lesions in any or all other
sites produced.  (cf. the principle of "double dissociation", a
favorite of my old prof, Hans-Lukas Teuber)

It is important also to DEFINE ONES TERMS.  As I pointed out in my
reply to jvall (q.v.) a rose is a rose is arose, perhaps, but "working
memory" is not "working memory" is not "working memory" UNLESS THEIR
OPERATIONAL DEFINITIONS AGREE.  You folks continue to act as if you
know what somebody is talking about when he uses the term "working
memory"; you do NOT unless you understand the experimental operations
defining it.





  Mishkin's (and other's) monkey lesions over the 
>past 20-30 years have only shown that disrupting a circuit by removing
its 
>elements, or by disrupting normal brain function, can interfere with
memory.
>
>
>>NMDA receptors are
>>involved in a putative molecular model of learning and memory, LTP.  
>Typically,
>>when you interfere with LTP, you interfere with memory. 
Interestingly, LTP
>>occurs primarily in the hippocampus and most is NMDA receptor
dependent.   I
>>don't think you can rule out the involvement of the hippocampus with
the
>>molecular  information out there.
>
>LTP probably exists as a means for plasticity--whether that plasticity
is for 
>learning and memory, that's another story.  (then there's the debate
that all 
>plasticity is learning...).  LTP and LTD have been shown to occur in
several 
>brain areas (e.g., hippocampus, cortex, cerebellum...).  Its hard to
deny that 
>the hippocampus is involved, but its only one node on the circuit.
>
>Jon
>




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