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What's a Brain Wave?

dag.stenberg at helsinki.nospam.fi dag.stenberg at helsinki.nospam.fi
Tue Apr 27 13:14:19 EST 1999


Cijadrachon <cijadra at zedat.fu-berlin.de> wrote:
> To Dag:

Sorry, I have a busy period (no experiments, but arranging things), so I
am not really actively in this room.

> > Nerve cells also may impulse in bursts and take a short break, and then fire again, 
> In deep sleep?  In which sectors (not) a lot?

Don't understand your definition of sector. This pattern occurs in all
stages of non-REM sleep.

> >unlike wakefulness, where the activity is much more 
> >ingoing.
> ?

Sorry, I meant ongoing. Continuous.

> >Both sigma sleep spindles, deep sleep delta waves, and the relaxed
> >wakefulness alpha rhythm reflect different relationships between
> >cerebral cortex 
> Where is the cerebral cortex?

You mean "where IN the cerebral cortex". I think this is rather widespread.
 
> >and two types of cell in the thalamus. 
> Which areas of the thalamus and which cells?

Thalamocortical projection neurons in the thalamic nuclei which project
to different parts of the cortex (these are glutamatergic projection
cells), and neurons in the thalamic reticular and intercalated nuclei
(these are GABA-ergic and inhibitory cells).  Nice oscillations occur as
the result of the couplings between these three cell types, wehich
contain a lot of different membrane channels. Different states in these
channels lead to different patterns of activity, and one has found that
they correlate with, for instance, active waking, relaxed waking, light
non-REM sleep, deep non-REM sleep.

> >The gamma frequency of attention may also be a fourth mode of relationship between
> >cortex 
> Which areas of the cortex?

Uh, I looked this up some months ago, and have forgotten it.
At least in motor and association areas, seems to be the quick answwer.

> >and thalamus. Once this has become known, one knows roughly what
> >signalling relationship exists between thalamus and cortex when the EEG
> >shows one of these wave patterns.

> I am usually not that interested in sequencer stuff,
> unless maybe I disagree because it does (not) do something

It is strange that you so often refer to brain function as if it were a
computer (CPU, sequencer, etc.). I would have thought that you would be
very much into parallel processing and multiprocessor analogy. Of
course, you write somewhere that you find parlalel processing difficult.
I would have guessed that you would find thinking in sequences more
difficult. I suppose that this only shows how little I understand after
all. 

> Why does the thalamus interest you that much?
It does not interest me as much as some other areas, like the dorsal
raphe, the locus coeruleus, the pedunculopontine nucleus, and the
cholinergic basal forebrain. But the thalamus IS so important for
vigilance, that one cannot simply ignore it.

> I tried to find some logic following some
> alpha-beta-gamma-delta-epsilon...omega system 
> in the energy ranges when at puzzling over why those names were picked

I think they just gave them names in the order that they started to find
them interesting.There seems to be no other logic.

Dag Stenberg




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