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Deja vu

F. Frank LeFever flefever at ix.netcom.com
Sun Feb 28 22:25:32 EST 1999


re "excreting familiarity" ("secreting'?): just a metaphore.  No
special substantive excretion/secretion (hormonal, neurochemical) in
mind.

I'd compare it to the way other brain regions excrete/secrete other
feeling states, given that the leap from neural activity to subjective
experience is (in principle) a Mystery (in the classic sense, i.e.
unknowable; in contrast to the modern vulgarization of the word to
denote a puzzle hard but fun to solve--as in Agatha Christie), except
that we can in these other conditions describe neural events in some
detail.

That is, excrete/secrete is unnecessarily vague when talking about (for
ex.) the amygdala and conditioned fear, given that LeDoux and others
have traced out the paths to various components of the overall "fear"
response...

F. LeFever





In <IR0DjFAgcD22EwhX at hermit0.demon.co.uk> Nick Medford
<nick at hermit0.demon.co.uk> writes: 
>
>In article <7b9au8$bhl at dfw-ixnews4.ix.netcom.com>, F. Frank LeFever
><flefever at ix.netcom.com> writes
>>
>>One of these days, I'll bring home proper citation for my comments in
>>Int. J. Neuroscience (c. 5 yrs ago?), summarizing Mortimer Mishkin's
>>talk in a NYNG conference I had organized.  Among other things,
>>discussed two-way comounication in cortical streams carrying input
from
>>visual cortex to hippocampus, and back out again to posterior
>>association cortex, problem of distinguishing between current
percepts,
>>hallucinations, and vivid memories.
>>
>>In that context, cited Hughlings Jackson's descriptions of "uncinate
>>fits", i.e. seizures arising in the uncus, with "dreamy states"
>>sometimes involving aberrations in the sense of familiarity--not only
>>dlefal vu, but also jamais vu (things well-known to you which "feel"
>>unfamiliar, strange).
>>
>>Usually, the problem is put in terms of a specific event which seems
to
>>be re-experienced, because of the strong sense of familiarity each
>>detail of the event SEEMS to evoke.
>>
>>I emphasize "seems to evoke", because one of his footnotes reports a
>>very articulate and thoughtful patient who describes a very strong
>>sense of familiarity, but--of what, he did not know.
>>
>I think this is an important point. Clinically the deja-vu experience
>often has this "elusive" quality. Furthermore some of the odd feelings
>associated with epileptic "auras", while not usually classified as
deja-
>vu, have this kind of feel to them.
> 
>>I think this is an important clue.  My belief is that coincidence
>>between current events and previously experienced events provides a
>>necessary and sufficient signal for the uncus to "excrete" a sense of
>>familiarity.  Given the numerous ways in which thresholds can be
biased
>>in the nervous system, the uncus may be too ready or not ready enough
>>to "excrete" familiarity in a given situation; given multiple
>>possibilities for "short-circuits" and aberrant signals, its
>>"excretion" may become dissociated from normal recognition processes.
>>
>As a neurocognitive model this is certainly more plausible- or more
>refined,perhaps- than Sergio's idea. Seems to allow for deja-vu in
both
>epileptic and normal brain states. But what does "excreting
familiarity"
>really mean?! Do you have any refs on possible neurochemical
substrates
>for this?
> 
>>Given the human mind's incessant need to make sense of experience, it
>>is not surprising that an aberrant/dissociated sense of familiarity
is
>>asscribed to whatever else is happening: the experience is
rationalized
>>as "this has happened before"; and more sophisticated arguments
>>(invoking Einstein at times) follow...
>>
>>F. Frank LeFever, Ph.D.
>>New York Neuropsychology Group
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>In <36D73CA3.530F at uswest.net> "David B. Held" <dheld at uswest.net>
>>writes: 
>>>
>>>Howdy,
>>>
>>>      Perhaps this is another dead horse that has been senselessly
>>beaten
>>>here, but are there any neurophysiological explanations for deja vu?

>>>I've heard theories ranging from the somewhat plausible: Event is
>>>anomalously stored in LTM rapidly, thus creating the sensation of
>>>familiarity, as it accesses the instant "memory"; to the
>>>not-so-plausible: Deja vu is experienced when your timeline loops
onto
>>>itself, and touches a different temporal point, giving your mind
>>access
>>>to information from that time.
>>>      Does the first explanation have any truth to it, or is there a
>>better
>>>explanation?
>>>
>>>Dave
>>>
>>>-- 
>>>David Held, Chief Programmer   "As far as the laws of mathematics
>>refer
>>>Business Computing Solutions    to reality, they  are not  certain;
>>and
>>>email: dheld at uswest.net         as far as they are certain, they do
>>not
>>>web: www.uswest.net/~dheld      refer to  reality."  -  Albert
>>Einstein
>>
>
>-- 
>Nick Medford




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