"Matthew Kirkcaldie" <m.kirkcaldie at removethis.unsw.edu.au> wrote in
news:m.kirkcaldie-13BA9A.12442325112004 at tomahawk.comms.unsw.edu.au...
| In article <u24op0her5t9ss5tblv8kgei6nr7df5q0b at 4ax.com>,
| r norman <rsn_ at _comcast.net> wrote:
| > The traditional mediators of increased
| > local circulation include "metabolites"
| > like decreased pO2, increased pCO2,
| > increased extracellular [K+] and
| > adenosine. Any number of cellular
| > metabolic processes produce the
| > first two: nerve activity resulting in
| > increased Na/K pump activity is
| > certainly a leading candidate. The
| > same nerve activity will also increase
| > K+. These factors would readily
| > diffuse over distances up to 1 mm.
| > The pO2 and pCO2 changes would
| > readily cross glial cells, probably a
| > pH change could also, although the
| > astrocytes may shield arterioles from
| > K+ changes. However, you could
| > easily imagine that whatever metabolic
| > effect controls arteriolar dilation would
| > be something that the astrocytes were
| > adapted to pass through rather than
| > shield.
| > Using up ATP most definitely does
| > mean a change in the metabolic rate
| > of the cells -- the oxygen consump-
| > tion -- since brain ATP is essentially
| > produced completely by aerobic
| > metabolism. Even if the energy is
| > derived from local stores, you still
| > need oxygen and that
| > means blood flow.
|| These things are true in principle, of
| course, but are you really saying
| that the picomoles of K+ crossing the
| neural membrane during an AP are
| going to make a detectable dint in
| the millimolar K+ extracellular
| concentration a millimetre away?
I've not researched Dr. Norman's
comments, but can add, a bit, in-
general with respect to =all= ionic-
They are not restricted to small
distances, be-cause each ion forms
it's own "center-of-action", with
respect to which, =all= of any
individual ion's force-dynamics are
carried with it.
So, as an ion travels within the
nervous system, its force-dynamics
are acted-upon by the force-
dynamics of everything that sur-
rounds it -- which means, for in-
stance, if there's an intense neural
activation, there can be a =net=
action upon an individual ion that,
like a Child pumping a playground
swing, impells the ion through
These effects can, and do, operate
within the whole brain.
These extended force-dynamics
were, for instance, in the discussions
of glial tuning of "memory" that I've
discussed in long-former posts.
And all of this is =easily= observ-
able in the way that "memory"
for widely-'separated' subject-
realms can =only= be accessed
via an intervening "pumping"
I experience this sort of thing
routinely during my own research
efforts [allowing myself to, once
again, become "the lab-'rat'" :-], be-
cause the subject matter that I
deal with is multi-disciplinary.
When I wish to focus on data
that are widely-separated from
any current focus, I've always
got to do some work to "go" from
the 'current' focus to the widely-
During this "going", I'm =not=
'relearning' everything that I've
formerly-learned about the
data-realm to which I'm "going".
Although, yest, every 'time' I
so "migrate" between data-
realms, I do =always= learn
a bit of new stuff [knowing that
this new learning does always
occur is some of why I've act-
ively sought-out widely-separated
data realms, and continue to
routinely do so]. But what happens,
in the main, when I "go" between
widely-separated data-realms, is
just a glia-mediated physical
tuning of my brain's neural topo-
logy. The necessary refs are cited
During this glia-mediated physical
tuning, brains' neural topologies
literally "morph", structurally, so
that formerly-constructed micro-
mods are brought into optimal
3-D structural conformation.
All of this can be literally "watched"
as it's happening [although, care
is necessary while doing such
"watching", else the data-realm
"migration" that will actually occur
will be with respect to the "watching",
and not with respect to the problem-
focus "memory" shift. :-]
There are always stereotypical
'time' courses, during which one's
ability to, for instance, express one's
self optimally with respect to the
migrated-from data-realm and
the migrated-to data-realm varies
inversly, one from the other.
I can write volumes about this
stuff, but the point I want to em-
phasize, here, is as I discussed
above -- the overall dynamics
are =whole-brain= ionic-force
dynamics in which individual ions,
rather than being restricted to
the dynamics of an individual
experience, are literally moved
by the =net= ionic-flows in
which they exist.
All of this is flat-out easy to
Verify via careful radioactive
assays that follow 'individual'
ions' cumulative flows.
The problem in doing such
experiments is that it's probably
not ethical to impose radioactive
quantities of fundamental ions
within Humans, and doing it
in 'rats' means that the data-
realm "migration" becomes high-
ly-subjective re. Experimenters'
interpretations -- is the 'rat'
actually "going" between wide-
ly-separated data-realms? And
how can that be externally-
verified? Via widely-gualitatively-
separated experimental perform-
I've done it all in the ol' noggin'
lab, and can show 'anyone' else
in Neuroscience how to do the
These things are a bit of what
I want to discuss in-person with
folks, and, a bit, of why I want
to discuss stuff in-person with
folks -- their discussion requires
considerable attention to details
that are readily-accessible, but
which are routinely 'invisible' to
folks who are untrained with re-
spect to them.
There's a =lot= of stuff in NDT
that's analogous to this. I can't
'just' discuss it, in detail, in a
"broadcasted" way be-cause it's
a virtual Certainty that folks'd
stumble upon only bits and pieces
of the overall discussion, and, in
such "incompleteness", 'fly-off-
I cannot allow such, so I'm sit-
ting here, wanting to share all of
this stuff, in-detail, but having to
'wait' [interminably?] for in-
person opportunity to do so.
It's all so =Beautiful= that I'm
left 'wondering' if there's anyone
out-there who's actually interested
in doing Neuroscience :-]
Cheers, ken [k. p. collins]