IUBio

Brain Use/40 hertz

DK cooper17.spamless at xs4all.nl
Sun Jan 3 05:30:37 EST 1999


F. Frank LeFever wrote in message <
>Katrina's version of this question is interesting, even though it
>pushes us to a Clintonesque semantic dissection (what do you mean by
>"is", what does "is"; what do you mean by "moment").  If this traveling
>wave of activity goes so quickly, everything is happening "at one time"
>unless we are caught in Zeno's paradox...
>
>Even given a very fine grain definition of "a given moment", however, I
>wonder if it can be true.  For example, I am recalling slides Pat
>Goldman-Rakic shows illustrating activity in single cells in prefrontal
>cortex during "working memory" tasks (most recently, early December at
>ARNMD meeting in NYC): increases or decreases in activity (depending on
>the cell, depending on the phase of the task) are seen against a
>background of "continuous" activity--intermittent, of course, with a
>fine enough temporal resolution, but as continuous as possible in the
>cell's "resting" state.

Let me start out by saying that a) I am treating your above comments as
correct, having thought about them and correlated them to other reading but
not collected the cited info myself, and b) that I think we're not
necessarily talking about two different things; I think I just put it badly.
My comments were meant to be sort of an amalgam of things I'd picked up a
while ago, so I can't cite any particular source or claim any particular
veracity--but I think we may be voicing the same concepts from different
angles. The real upshot of what I was trying to say is that as I understand
it the entire brain cannot be working at the same level all the time; as
someone else pointed out, grand mal seizures seem to produce something of
the sort... and that the myth that parts of the brain remain dormant grew
out of the "fact" that every neuron is not firing simultaneously (or at
least in an identical fashion during simultaneous fire) at all times.
Here, I thought of an analogy: right now I am using 50% of my limbs, because
I am typing but sitting. I do not describe my legs as "dormant", even though
they are not in use at this moment, nor do I say that I only use 50% of my
limbs, even if I had a tendency to only use two at a time. I wasn't, in my
earlier comments, trying to portray some sort of localized but motile, rapid
structured pulse rushing about the surface of the brain until it hit
everywhere; I just meant that the firing is not always happening
simultaneously in each neuron... like footage of lightning travelling over
the surface of a storm. You can see that it's not everywhere at once, but
with a long exposure you can also see that in most cases it did get to damn
near everywhere (on the storm's surface), feeding outward from itself and
travelling to other areas of the cloudscape.

Now, I'm afraid I do have to complain about your use of "continuous
intermittent". This is, to me, like saying "sometimes always". A broken
continuity is simply no longer continuous.As near as damnit is no good in
precise science... however, I have a feeling you were trying to say that the
intermittence involves (temporal) gaps *so small* that the effect of the
firing can carry across the time gap, like electricity remaining briefly in
a wire after the current is cut, so that when the neuron re-fires the
original "charge" is not yet entirely gone. This would produce a sort of
oscillation, instead of a purely intermittent signal. Is that what you were
saying?

>
>Generally, isn't it CHANGE in rate of activity rather than activity
>(vs. non-activity) that is important?
>

Well, yes... that's why if all the neurons were firing all the time, in a
continuous signal, there would be very little opportunity for change-related
change. Well, I suppose that's not entirely true; if they oscillated between
low and high levels of work, it could well provide enough template
differences to work. However, some neurons do turn off sometimes, correct?
By turn off, I mean "not turn on, by which I mean "not fire".
Anyway, the thread is about the idea that massive numbers of connected
neurons do remain unfired, even static, even dormant, for at least much of
our lives. This is an idea I do not agree with, but it is the idea which was
under investigation when I joined this thread. I am only trying to provide a
plausible theoretical explanation for how people may have come to think it.

>>Katrina: is it your friend with the headache, in
>another post? what is a "physical" psychologist??  what we in US used
>to call a "physiological psychologist"?  but these were/are
>experimentalists, researchers and we would not say "practicing" in this
>case.  Can you clarify?)

Yes, sorry, just a matter of using words instead of terms. He fits your
description to a T. I had thought at one time he was a neuropsychologist,
but he says he is a research psychologist, yes indeed an experimentalist,
who does his research from the end of physical structures, chemicals, etc.,
rather than just talking to people about their thoughts or emotions. In
other words, one's seratonin level is a lot more interesting to him than
whether or not one is alarmed by carrots, except at the level where such
things may account for each other. It's his Dutch girlfriend who described
him as a "physical psychologist"; she'd apparrently just lost the "ological"
in translation, and I failed to pick it back up. By practicing, my own word
at this point, not his, I meant that he does research, teaches sometimes,
and writes the occasional book, instead of just sitting around with his
degree or something.

--Katrina






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