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In the litterature which I have access to
brainwaves are apparently percieved as an
accompanying phenomenon,
relative to the thing that really matters:
neural activity.
I suggest that this is turned upside down:
Brainwaves are the essence, and carriers of cognition. Neural activity is an accompanying phenomenon. |
(Actually it's more likely a dialectal relationship).
Normally four types of brainwaves are identifyed,
depending on the frequency.
I added "white noise".
Different areas of the cortex may emit different
types of waves at one time,
and different types of waves may be emitted
from one particular area -- when we say that
e.g. alphawaves are emitted,
we mean that there are more alphawaves than anything else.
Different levels of consciousness are identifyed, first and foremost the waking state and four phases of sleep, 1.-4. below.
I added waking state as phase 0.
REM-sleep looks very much like drowsiness on the EEG,
but it is quite difficult to awake the sleeping person,
in contrast to drowsiness and waking up.
You move from the waking state through phases 1-2-3-4,
and from there 4-3-2-REM,
and then down again: REM-2-3-4.
REM-sleep is roughly equivalent to dream periods;
there are about four or five of those through the night.
If you wake up naturally (without an alarm clock),
you will most likely be coming out of a REM-phase
(i.e. you will awaken from a dream).
It may be quite unpleasant to awaken from phase 4, 3 or 2.
Deep sleep is concentrated in the beginning of the night
(i.e. the pattern above is replaced with REM-2-3-2-REM
later on),
and the first period of deep sleep is normally the longest one.
In contrast the REM-periods grow longer towards the end of sleep.
Actually there are higher frequencies than betawaves.
Any wave, regardless of its shape, may be represented
by the sum of sine-waves of
ever higher frequency.
That is, if your brain is emitting waves of the frequency 13,
it is simultaneously emitting waves of the frequency 26, 39, 52 etc.
This is quite analogous to touching the A-string of a guitar
(or similarly on a piano).
The resulting sound contains in principle
infinitely many overtones,
whose frequencies are multiples of the basic one.
| pitch | frequency/Hz |
| A | 100 |
| A e |
220 330 |
| A c# e g |
440 550 660 770 |
| A h c# : |
880 990 1100 : |
| A : h : |
1760 1870 1980 : |
The square or cube of two, or any power of two,
multiplied with 110 Hz results in a frequency which also corresponds
with an A.
Musicians distinguish between the various A's,
and have names for them.
The frequencies are exact for the A's,
but approximate for the other notes.
Or rather, it is the pitch which is an approximation,
i.e. an A of 110 Hz does indeed have an overtone of 330 Hz,
but the frequency of the e is not precisely 330 Hz,
at least not on a piano of standard contemporary tuning.
Jahnsen & Laursen
("Hjernevindinger vundet af ny forskning", Munksgaard, 1990)
claim that the occurrence of brainwaves on the cortex
are the result of a peculiarity
in the function of
the neurons of the Thalamus.
Paradoxically, when stimulated on their
inhibitory (!) synapses,
they respond by emitting regular, slow signals
with a frequency lower than 4 Hz.
That's possible. Maybe that's the origin of brainwaves.
I feel that it ought to be possible to explain the phenomenon
by neuronal activity in the cortex itself,
namely as a number of neurons activating each others excitory
synapses in some kind of circuit.
There has to be millions of such circuits in the cortex.
On the other hand, the signals from the Thalamus may
synchronize the brainwaves,
or cause a quicker synchronization.
A sense impression is transmitted to the central nervous system
as an electrical impulse.
So, electrical impulses are information.
When seen from the central nervous system
a sense impression impulse, or perhaps many single impulses,
may be regarded as random signals, and hence as "white noise",
i.e. "waves" of an extremely high frequency.
| I propose that high frequency waves are the same as ultra short memory, and that this memory comprises, among other things, sense impressions, "overtones" of the rest of the electrical circuit, and some random noise. |
Now we are ready to make the big jump:
| Consciousness and memory are the same as the electrical circuit. |
In other words, it's not the neurons or the synapses
or anything inside them
which "holds" consciousness,
but rather the circuitry.
I choose to identify consciousness and memory and thinking
at this stage.
It's all the same.
| Sensing and ultrashort memory must necessarily be relatively independent of the underlying network, i.e. of the number and connections fo the neurons etc, since they are lost with various forms of unconsciousness. |
Things can be forgotten.
What is normally termed Short Term Memory
("the telephone number is...")
may be stored in e.g. beta-waves.
| The Long Term Memory is dependent on the underlying network, as it is preserved during loss of consciousness, submission to electric schocks etc. |
I propose that the lower frequency,
the higher the dependency on the network.
Now for the exciting stuff.
By Memory is meant:
permanent storage of a sense impression,
e.g. of a visual impression.
We do not consider attempts to learn a telephone number.
I imagine this happens in several phases:
Synchronization of beta- and alphawaves are used as an example.
The principle is the same, regardless.
Somehow some (not all!) Short Term Memory,
which we imagine to be stored in betawaves,
must be represented in the Long Term Memory
-- either because we want it so (learning),
or involuntarily.
In the model suggested here this means that
high frequency waves are represented in low frequency waves.
It is not problematic to imagine how this might be achieved.
For instance, Alphawaves might be "folded" into Betawaves
so that the resulting Betawave ends up containing
the new information as well as the old one.
At least that is easy to imagine if you are a mathematician,
but you may wish to consult the word list below.
Similarly Alphawaves may be "folded"
and thus represented in waves of lower frequency.
How are low frequency waves represented in the network?
How do neurons find out how they should connect?
I have no explanation for that.
But consider this analogy:
How does sand know how to fall on a vibrating plate of steel?
It just does!
When a plate of steel (for instance) vibrates with certain frequency,
sand falling on it will form an aestethically pleasing pattern.
If the frequency is doubled,
a similar, but more complex pattern ermerges.
| Similarly, one can imagine that delta waves somehow promotes the connection of some neurons, and hampers others. Slowly, since axons and dendrites grow with appr. 1 centimeter per month. |
I imagine that this takes place during deep sleep,
seeing that deep sleep generally has something to do with
physical regeneration
(e.g. through the secretion of growht hormone).
During electrochok all other electrical activity is suppressed.
Upon regaining consciousness the Long Term Memory
is kept.
Therefore there must be something in the network
which represents the long term memory.
But the network has a particular configuration.
Neurons A and B are connected, and they will still be connected
after an electrochok.
I believe that the connections of the network
determine that some low frequency waves are possible
and others are not.
Just as a piano
has some possibilities, a guitar has others,
and a grand piano still others.
Short Term Memory may be "unfolded" from
Low Waves in the reverse process of the above.
"Thinking", or actually much more generally: "cognitive activity".
Thinking, emotions etc. might consist of adjusting
brain waves to each other;
in particular adjusting "noise" and Betawaves,
and adjusting Betawaves and Alphawaves.
What kind of "adjustment" is required is another matter.
Perhaps it's as simple as tuning a guitar or a piano.
Or perhaps it's more like when a jazz orchestra is improvising.
This theory has some advantages over most others that I have
come about.
It explains a number of facts know from brain research:
Well, I have some ideas about that as well,
but I'm holding it a bit.
1)
It has come to my attention that
Chrisoph von der Malsburg
was the first (1986) to develop the idea of
waves as an expression of the cooperation between
neurons.
In addition
Francis Crick & Christof Koch
have been working on an idea
around 1989-90,
about "waves" being the bearers of
consciousness.
There is experimental evidence in that direction:
| Particular neurons in the visual cortex of a cat will emit 40 Hz waves while they are percieving the same object. |
The synchronized activity
seems to indicate that the
neurons "agree" that they are percieving
the same object.
I take this as supportive of my theory
(and then it may not be "mine").
Wolf Singer (Frankfurt) has written about this
in Science, 1990.
2) It seems that the translation
from Short Term Memory
to Long Term Memory
is heavily dependant on
neuronal activity in the hippocampus.
This is bad news for my theory.
Oh, well.
folding
denotes a type of calculation whereby two or more
mathematical functions -- which might describe waves --
are represented by one mathematical function.
The original functions may be unfolded at a later stage.
This principle was applied in quadrophonia.
On a vinyl disc there are only two channels (left and right),
but on a quadrophonic record four channels are "folded",
two by two.
In principle all four might have been folded into one.
Fourier
French mathematician who showed how any wave may
be described as a sum of sine waves:
f(x) = a0 + a1 * sin x + a2 * sin 2x + a3 * sin 3x + ...
a0-1-2- may be calculated from f; i.e. from the shape of the wave over a limited interval it is possible to calculate a0-1-2...
The sine function is only one example out of a number of possibilities,
but it is a probably a good bet since it results in simpler calculations.
The suggestion in this work is that it exactly this,
or something similar,
that the brain does when data are stored and refound,
and when we are thinking.
circuit all electrical activity in the brain
network means "hardware" in this work,
by which is meant
neurons, axons, dendrites, synapses a.o.
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Mike L. Griebel,
mgriebel@hotmail.com
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