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Memories of Fear

kenneth Collins kpaulc at earthlink.net
Mon Jan 3 13:07:29 EST 2000


Dag Stenberg wrote:
> 
> Ron Blue wrote:
> > http://www.usc.edu/ext-relations/news_service/releases/stories/36023.html
> 
> I looked up the article (Garcia et al., Nature 402:294-296, 1999).
> I (too) wish to comment just shortly.
> While it has been known for a long time that the amygdala is involved in
> fear, the mechanisms of this involvement has mostly been unknown. The
> anatomy and interconnections of the various nuclei of the amygdala have
> been mapped in detail less than 10 years ago.

i'm sorry, Dag. all the necessary refs were cited in AoK, and they all
existed much earlier than 10 years ago.

what was 'lacking' was what's provided in AoK.

all the refs were out-there, as stand-alone papers. before AoK (NDT),
nobody integrated everything, and so (as is explained in AoK), there was
an Illusion of there 'not being enough known about the brain'.

but when one does the cross-correlation, the stuff of the formerly
non-integrated papers becomes 'self-organizing'.

that is, when one does the cross-correlation, it's seen that the stuff
of this or that paper 'delimits' and augments particular aspects of the
stuff that's discussed in this or that other paper.

when one does such across the Neuroscientific stacks, one =can only=
'arrive' at NDT's tightly-integrated synthesis.

it's 'just' a real Sorrow... for hundreds of years, while being Taught
how to do this or that very-worthy stuff, Grad Students were also Taught
how =not= to solve the brain, because they were Taught =not= to do the
cross-correlation integration.

imagine my Sorrow when, after having seen the deficit, and after having
done the work necessary to remove that deficit, i'm treated as an 'ogre'
by folks who were Taught not to do the cross-correlation integration,
and the work i did, at awesome personal cost, is forsaken.

such is Hell-on-Earth stuff.

> It was shown in 1991 that
> stimulation of the basolateral nucleus (BL) of the amygdala inhibits
> neurons in the medial prefrontal nucleus. It has been shown, in the
> '90s, that the auditory system projects to BL, and separately that both
> unconditioned and conditioned stimuli induce long-term potentiation of
> auditory-evoked events in the BL.
>   What these guys now showed (greatly shortened, hopefully not messed up
> by me) was that neurons in the prelimbic (medial prefrontal, MPF) cortex
> were inhibited by a fear stimulus, but less in response to a conditioned
> stimulus, if the animals had been post-conditioned to reduce the
> behavioral fear response (freezing). The degree of inhibition in MPF was
> thus related to the level of CS-evoked freezing behavior. to find out
> the involvement of the maygdala, they then made bi- or unilateral
> amygdalectomy to some animals. Sham-lesioned animals had a stong
> inhibition of MPF to fear-inducing CS, bilaterally lesioned no
> inhibition, and unilaterally lesioned had suppressed inhibition of MPF
> in the lesioned side. The freezing response correlated inversely with
> the lesion: it was greatest in the sham-lesioned, intermediate in
> unilaterally lesioned and less in the bilaterally lesioned.
>   The pathways (BL to MPF) remain to be determined, as the direct BL-MPF
> pathway involves excitation.
>   The authors think that these experiments may illustrate the importance
> of the MPF in decision-making: if the MPF predicts danger, its neurons
> are strongly inhibited, and this is a signal to other circuits. The BL
> projection to the MPF will teach the MPF whether there is danger or not.
> 
> My point with all this is that such experiments and their forthcoming
> extensions tell us HOW various brain areas function on a
> pathway-transmitter-cellularmessenger-genomic  level, which is
> enormously more useful for medical applications that just knowing THAT
> these areas are in some way involved, or even just that their level of
> excitation or inhibition (and pray - in what neurons of this complex
> mass of circuits?) changes. In my view, the present work must be
> followed by more detail work concerning cellular and molecular
> mechanisms, and we will see such results in a few years.

while i agree, completely, that ever more detail is necessary, i, again,
assert that it's important to integrate the stuff that's already been
accumulated, and =then= pursue stuff in more detail.

why?

because the integrated understanding flat-out points-the-way to all the
work that remains to be done.

why forsake such?

why not mount all the 'Jewels' in a 'crown' and wear it as a
'thinking-cap'?

why not, when such serves understanding so well?

ken (K. P. Collins)




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