Locus Coeruleus & DNAB - Recent Hypotheses ?
k.p.collins at worldnet.att.net
Sat Jun 14 03:11:42 EST 2003
"David Longley" <David at longley.demon.co.uk> wrote in message
news:IiPQ6nASKk6+EwT2 at longley.demon.co.uk...
| Anyone know of what the most favoured
| hypothesis currently is regarding
| ascending NA from the LC?
| David Longley
NDT's Position [Briefly]:
The two 'halves' of the Noradrenergic
[NA] sub-system are the evolutionary-
remnant of Coelenterata's radially-
symmetrical nervous system 'para-
digm', and functions in a closely-
analogous way with respect to tuning
the "supersystem" within selective-
attention. While remaining sub-con-
scious, the ascending NA fibers
of the Locus Ceruleous [LC] project
this functionality into Consciousness.
Everything within nervous systems is
topologically-continuous, but this asc-
ending NA system is directly-continuous
in it's particular-functional realm with
septal "ramp architecture" that is dis-
cussed in AoK, Ap3 front-center orient-
ation with respect to relative novelty, all
of which is governed by the hippocampal
TD E/I-minimization mechanism as is
discussed in AoK, Ap5.
The Key to comprehending this is given
on page 696 of =Principles of Neuro-
science, Third Edition, by E. R. Kandel,
J. H. Schwartz, and T. M. Jessel, 1991,
ISBN: 0-444-01562-0 [The last two sen-
tences constitute the "Key", but I've in-
cluded additional context:
"When neruons of the locus ceru;eus are
activated by novel sensory input, they res-
pond as a group [NQI, see below] with an
increased burst of activity. This coordinate
response to a change in sensory [NQI,
see below] input suggests that these neur-
ons have a role in orienting and attending
to sudden contrasting or aversive sensory
input [NQI, see below].
How does this noradrenergic [sub-]system
modulate neural activity [NQI, see below]?
To examine this question Roger Nicoll and
his colleagues studied the response of hip-
pocampal neurons, one of the [globally-dis-
tributed "neural areosol"] targets of the loc-
us ceruleous, and found that norepinephrine
increases the excitability of these cells. Nor-
epinephrine activates [beta]-adrenergic rec-
eptors on hippocampal neurons, which act-
ivate the cAMP-dependent protein kinase
[which is an example of molecular';eve;'
'addressing' via 3-D energydynamics] lead-
ing to Ca^2+-activated K^+ conductance.
In other cortical neurons Floyd Bloom and
his colleagues found that norepinephrine
activates [alpha]-adrenergic receptors, pro-
ducing the opposite effect on cellular excit-
ability. In these cells, norepinephrine caus-
es a slow hyperpolerization and a decrease
in the rate of spontaneous [NQI, see below]
The this's exactly analogous to Coelenterata
predation behavior in which the nervous sys-
tem of the 'jellyfish' is activated in a way that
results in a radially-symmetric way that has
it's radially-biased focus on the prey with the
result being that the organism's 'tentacles'
engulf the prey.
The in-stream emision of NA that occurs in
the NA fibers is analogous to the paralyzing
emissions of the coelenterata's 'tentacles',
except that it acts within the neural topology
with respect to the neural topology's 'prey':
the 'object' of attention. The resultant TD
imposed quiesence is analogously-biased,
which 'damps' attention to stuff other than the
'target' of attention. The "coordinate response"
is, therefore, not an equipotential 'burst', but is,
itself tuned in the radially-symmetric, biased-
toward-target way [this is a Prediction of NDT].
The TD radially-biased 'quiesence' is not a
reduction of "spontaneous" activity but a quiet-
ing of otherwise TD E/I-minimization-directed
information-processing activity, and is, there-
fore more-than-sensory in nature.
The Locus Ceruleus does not stand-alone. It
receives co-ordinating activation that inte-
grates the functionality described seamlessly
within the "supersystem" in efferent and affer-
'Jamming' the functionality of the LC via drugs
is particularly-hazardous to nervous system
functionality be-cause the LC neurons 'adjust'
their outputs accordingly [more activation-
dependence all the way down] which results
in drug-dependent, skewed attention that, as
I've discussed in former posts is strongly-biased
with respect to obtaining the drug. This occurs
be-cause withdrawal of the drug results in the
elevation of LC activation, which, as above,
'focuses' selective attention in a way that
'shuts-down' everything but the artificially-in-
duced drug-correlated 'target' - rendering
behavior, otherwise, 'crippled'.
Although it's not in the original wuery, the desc-
ending lateral tegmental NS subsystem is anal-
ogous to Coelenterats's 'preparation-to-digest'
[its prey] functionality, in mammals, tuning
sympathetic functionality [which is part of "amyg-
dalar priming" as it is discussed in AoK, Ap5.
As is pointed out in AoK, Ap4, everything here
reduces directly to TD E/I-minimization ["This
'fundamental wisdom" [can] be traced through-
out phylogeny to the level of nervous systems
exhibiting radial symmetry [...]"
Other than tracing the "special topological
homeomorphism" in-it, and through-it, I didn't
include brain-stem stuff in AoK because AoK
was written as an =Introduction= to NDT, and
the structural order of the brain is 'primitive',
and, therefore, its inclusion would've been an
'obstacle' to introductory-comprehension of
the basics of NDT that are presented in AoK.
[The brain stem contains a lot of evolutionarily-
added-on functionality 'bridges' [which, if
Humanity doesn't End itself first] will become
progressively more-elegantly-laid-out as the
Future of Humanity unfolds. This will occur al-
ways in a way that converges upon maximized
efficiency of TD E/I-minimization. But, for now,
the brain stem is a bit to structurally-'difficult' for
AoK's Introductory Purpose with respect to
Enabling Readers to See TD E/I-minimization.
I've done what's here only because I Trust that
there're folks in b.n who've Grasped NDT's
Fundamentals and who will, therefore, immed-
iately See what's discussed in this msg.
There's much-more with respect to this LC stuff,
but it requires working from the perspective of
other nervous system 'components' - to 'walk-
through' the "supersystem" integrating what's
Everything in NDT is in this all sub-systems-to-all-
The Neuroscientific Usefulness of NDT is that,
once one gets the 'hang of' the Fundamentals,
such 'walking-through' the "supersystem" be-
comes flat-out straight-forward [which is what
I discussed recently with respect to the 3-D
energydynamics 'map', and how it can be read-
K. P. Collins
"Schmitd! Schmitd! Ve vill build a Shapel!"
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