Working memory--old Penfield story

F. Frank LeFever flefever at ix.netcom.com
Sun Mar 15 00:52:48 EST 1998


Dear Cheng--

I don't know what country you're sending from or what access you have
to recent/current scientific literature, but you should make an effort
to consult SOMETHING recent before you attempt another "volume"!

You apparently do not grasp ANY of the current uses of "working" in the
phrase "working memory".

You are apparently unaware that it is commonly accepted that the
hippocampus is not the PLACE where memories are stored, but rather it
is the channel through which things-to-be-memories are sent back into
the association cortex you refer to.   There are many elegant studies
on the rate at which this "consolidation" into permanent memories
occurs, and some data on the processes (at a molecular level) involved.

See, for a beginning, Mortimer Mishkin's work over the past 20-30
years...(and see also his work on distinguishing this sort of memory
from the sort of "habit" which apparently involves the basal ganglia
more than the hippocampus).

In your account, you seem to suppose tht the point of entry is ipso
facto the point of permanent registration of sensory inputs.  Mishkin
and other have shown the step by step progress of this input from one
level to another within this cortex ON THE WAY TO THE HIPPOCAMPUS, from
which it RETURNS to the cortical areas through which these "streams"
had passed, and only THEN being "registered" as a (to be) permanent
memory.

(As a neuropsychologist, I have been especially interested in the
distinction between the dorsal and ventral visual streams and the
different kinds of information carried--and have presented some work on
efforts to measure the two different kinds of visual memory within the
same neuropsych test...)

In any case, we are talking about a kind of memory which is NOT what is
usually meant by "working" memory (at the level of primates, not rats).
In my prior example, Joachim Fuster's work, the prefrontal cortex
selectively activates/enhances/modulates those posterior cortical
memories in the performance of a task requiring brief use of specific
information.

Frank LeFever






In <3509C70B.46AA at postoffice.idirect.com> K C Cheng
<kccheng at postoffice.idirect.com> writes: 
>
>austin seo wrote:
>> =
>
>> I didn't think anyone considered the hippocampus to be involved in
>> "working" memory...I always thought the dogma was the involvement of
th=
>e
>> prefrontal cortex...
>> =
>
>> Lab wrote:
>> =
>
>> > A few weeks ago I remember reading something on this newsgroup
about
>> > work with evoked potentials to localize the function (or role) of
>> > hippocampus in working memory.  However, I have found little in
the
>> > literature about hippocampus and working memory, and even less
about
>> > using EPs to explore that issue. Can someone point me the right
>> > direction?
>> =
>
>> --
>> =
>
>> Austin Seo (Hae Jin)
>> =
>
>> Graduate Programme in Neuroscience
>> Centre for Molecular Medicine and Therapeutics
>> e-mail: haejin at netinfo.ubc.ca
>Re. Working memory:
>The most scientific theory on this is derived from the fact that the
>various primary sensory cortices( e.g. vision, smell, hearing, etc.) =
>
>are the most immedidate  sites to receive the most intense sensory
>inputs from their respective pathways.  Hence, the primary visual
>cortices are the primary  vision memory sites,  auditory cortices
being
>the primary memory sites for auditory memories, etc.     Then,  such
>primary memories radiate out into the various association areas, and
>other more distant areas of the brain.    From Penfield's experiments,
=
>
>evidently  these primary memories converge into associated memories in
>areas where for instance,  the visual and auditory fibers come
>together.  When  such an area  was stimulated by electrodes,  the
>patient recalled both voices and visions associated with specific
events
>of the past.  The frontal and prefrontal areas  which are believed to
be
>engaged  also in thinking, etc, as with many other parts of the brain;
>of course depend on the activation of various primary memory sites
such
>as the visual cortices for visual recall,  etc., =
>
>for thoughts to have the necessary memory pieces [ for thought
>formation].  These processes as a whole provide what is sensed to be
>"working memory."   Otherwise, memories would not be  "working."  =
>
>Explained in my future volumes, but an  introduction is at =
>
>http://webhome.idirect.com/~kccheng
> =
>
>-- =
>
>kccheng:=B9=BF=C2=F7=F7=F7=F7=F7=A5=BB=BC=A7




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