A Theory of Sleep

Brian zhil at online.no
Tue Aug 21 08:10:52 EST 2001


"yan king yin" <y.k.y@(no spam please)lycos.com> skrev i melding
news:9lrfb4$3uq5 at imsp212.netvigator.com...
> "Brian" <zhil at online.no>:
> > Hmm, that is longterm memory, but short-time memory goes through the
> > selective attention system (Thalamus) and then through Hippocampus.
> > I wonder if attention is directly connected to short-time memory, and
that
> > somehow stimulates myelination......
> > But what perplexes me are those changes of levels in myelination you
> > mentioned.
> > Anyway, correct me if I'm mistaken - "Conversations vith Neils Brain" is
> > quite good, but there are more to it I suspect.
>
> I just read some of "Conversations with Neils Brain", the part about
> thalamus and selective attention is interesting. I'd like to learn more
> about the thalamus.

You need to go through more of the book, I spent some time digesting
what I have read.
They mention how the memory works more extensively.
Not just the output.
>From "Life" they say that the Hippocampus is necessary in
transfer of short-time memory to long-time memory (page 968, memory).

"Conversations" were published in 1994, and "Life" (the edition that I have)
was printed in 1998 (upgraded from a previous version from 1997).
There doesn't seem to be any great changes between them on this point
(regarding "Conversations" and "Life").

When they discuss memory, they also mention that cellular change during
sleep as you mentioned earlier (page 966).
Non-REM sleep were characterized by a decrease in responsiveness of neurons
in the Thalamus-region and the cerebral cortex.
And later: One hypothesis was that non-REM sleep restored the
energy-reserves
as well (no big surprise there).
And about REM-sleep, it is familiar in all mammals, so "it is probably a
rather
basic, cellular function."
Which reminds me a little of your first post in this thread.

> Im wondering, do you think the hippocampus really processes memory
> engrams and transfer them around? I ask this because the main output
> of the hippocampus neurons is via the fornix, and it looks rather thin.
> The hippocampus have extensive input from cortex, so it might be able
> to get the memories input. But its output (correct me if im wrong) is
> mainly to the mammillary bodies and they are really small.

I think that Hippocampus is one part of what we call consciousness
(a 'flashlight' which lights up necessary memories).
Of course with the Thalamus, as it relays the sensory information.
The cortex processes these memories and give an output which
transfers to the motor-area if we IE want to move an arm or to
the temporal lobe if we want to form a question or answer one.

It might be that it is a one-way transfer and you ask:
"I ask this because the main output of the hippocampus neurons is
via the fornix, and it looks rather thin."
It might simply be a feedback loop, to make sure the 'flashlight' doesn't
overload.

_Consciousness_ as an overall, is a sum of all our parts;not just the
'flashlight' (short-time memory [Hippocampus] and sensory information
[Thalamus]), but also longtime memory [Cerebral Cortex].

Now, this is as far as I've understood this, so if anybody wants to
correct me - by all means, please do !!

Brian





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