CHAPTER 1 INTRODUCTION
One of the problems facing neural science is how to explain
evidence that local lesions in the brain do not selectively impair one
or another memory trace. Note that in a hologram, restrictive damage
does not disrupt the stored information because it has become
distributed. The information has become blurred over the entire extent
of the holographic film, but in a precise fashion that it can be
deblurred by performing the inverse procedure.
This paper will discuss in detail the concept of a holograph and the
evidence Karl Pribram uses to support the idea that the brain
implements holonomic transformations that distribute episodic
information over regions of the brain (and later "refocuses"
them into a form in which we re-member). Particular emphasis will be
placed on the visual system since its the best characterized in the
neurosciences. Evidence will be examined that bears on the validity of
Pribram's theory and the more conventional ideas that images are
directly stored in the brain in the form of points and edges (without
any transformation that distributes the information over large
regions). Where possible, the same evidence (for the visual system)
will be used to evaluate both theories.
1. Holonomic theory where Fourier-like transformations store
information of the sensory modalities in the spectral (or frequency)
domain. The sensory stimulus is spread out (or distributed) over a
region of the brain. A particular example (in the case of vision)
would be that particular cortical cells respond to the spatial
frequencies of the visual stimulus.
2. The more conventional theory that particular features of the
untransformed sensory stimulus is stored in separate places in the
brain. A particular example (in vision) would be that particular
visual cortical cells respond to edges or bar widths in the visual
stimulus.
It will be necessary in this report to first explain the concepts of a
hologram and Fourier transforms before the physiological experiments
can be understood. Bear in mind that the discursion into these other
fields serves a purpose for later in the report.
Karl Pribram's holonomic theory reviews evidence that the dendritic
processes function to take a "spectral" transformation of
the "episodes of perception". This transformed
"spectral" information is stored distributed over large
numbers of neurons. When the episode is remembered, an inverse
transformation occurs that is also a result of dendritic processes. It
is the process of transformation that gives us conscious awareness.
Chapter 2 will outline the basic concept of a hologram and start to
introduce Pribram's holonomic brain theory.
Chapter 3 will briefly describe the conventional accepted view of the
pathway of neural processing (with particular emphasis on the visual
system). The main computational event in this view is the generation
of the action potential.
Chapter 4 will review the evidence for the alternative holonomic view.
The holonomic theory is based on evidence that the main computational
event of neurons is the polarizations and hyper polarizations at the
dendritic membranes of neurons. The evidence will be reviewed that
supports the notion that these dendritic processes effectively take
something close to a Fourier transform.
CHAPTER 2 HOLOGRAMS
What is holography?
The word "holography" is derived from Greek roots meaning
"complete writing". The idea is that every part of "the
writing" contains information about the whole. A hologram (the
material manifestation of a holograph) is a photographic emulsion in
which information about a scene is recorded in a very special way.
When the hologram is illuminated, you see a realistic,
three-dimensional representation of the scene. If you cut the
holographic photographic plate up into small pieces, the whole image
can still be extracted from any of them (although with some loss of
clarity). Pribram uses the term holonomy to refer to a dynamic (or
changing) hologram.
The Hologram Relationship
The basic idea of a hologram can be understood without even
considering the holograms found in novelty stores. The idea is simply
that each part contains some information of the whole. Or stated
another way, the information (or features) are not localized, but
distributed. To clarify this concept, consider the following thought
experiments (demonstrations). As will be demonstrated, light is in the
holographic domain before it gets transformed (focused) by a lens.
Demonstration #1. Remove the converging lens in a slide projector that
forms the image. Place a slide in the projector and project the light
onto a screen. No image will form. Technically, the light incident on
the screen is in a holographic form. Each point on the screen is
receiving information from every point from the slide. If a converging
lens is placed at a location between the screen and the slide
projector an image can be formed on the screen. The lens can now be
moved to new locations in a plane cutting through the light path to
the screen and in each case a complete image is formed (Taylor, 1978).
Demonstration #2. The above principle can be demonstrated with using a
camera. Consider taking pictures of an object (for example, a far-away
mountain). You take a picture, then move over a few feet and take
another one. You move over a few more feet and take another one. Upon
getting the pictures developed, they all look about the same. This
demonstrates the idea that the information necessary to form the image
was present at each of the locations that you took the pictures.
Additionally, if you look at an object very far away, then tilt your
head to the side, you can still see the object. The light incident on
your eye in both positions was sufficient to form the whole image.
Demonstration #3. Take a pair of binoculars. Just look through one
side focusing at a distant object. Now place your fingers in front of
the lens so that only light coming from in-between your fingers enters
the monocular. You will still see the whole image. If you bring your
fingers together so that the light enters only through tiny slits, the
whole image will still be present, only dimmer (and there will be some
loss of resolution) . If you rotate your hand, exposing the light to
different parts of the lens, the whole image can still be formed. This
is another representation that the light incident at the surface of
the lens at any point is in a holographic form.
Demonstration #4. A pinhole camera represents a special case where an
image can be formed without using a lens (without taking a
transformation). Note that if the pinhole is moved over a bit, the
image still forms. This demonstrates the rudimentary idea of the whole
being included in a part (the part being the area of the pinhole). All
of the information necessary to produce the image is contained in the
area of the pinhole. A lens functions to allow the light incident on a
larger area to all be transformed (focused) to form an image. This
will improve both image resolution and light gathering capability.
It is perhaps unfortunate that most physiology textbooks use a figure
something like the following (figure 1) to describe the operation of
the eye.

Figure 1
The above figure doesn't express the transform-taking aspect of a
lens. The above figure is really more indicative of a pinhole camera.
Figure 4 (shown later in the report) gives a better depiction of what
happens at the lens of the eye.
Mathematically (in one implementation), a Fourier transform
converts a function of time f(t) into a function of frequency F(jw)
where the j indicates that it is a complex function of frequency. In
other words, a Fourier transform can convert a signal from the time
domain to the frequency domain. A Fourier transform could also be used
to convert something from a spatial locational domain (the coordinates
in space) to a frequency domain (more about this later).
The idea (the mathematics) of the Fourier transform is independent
of what the data sets represent. It will be argued that if the brain
performs a Fourier transform for visual stimuli, then it is possible
that it also performs a Fourier transform for the other senses also
(hearing, taste, smell, touch).
The same principle can be shown with optics. Consider, for example,
that a large telescope lens (or mirror) can resolve two distinct
images (for example two stars that only have a small angle separating
them in respect to us). A smaller telescope lens (or mirror) will not
be able to resolve (separate) those two stars. Likewise, small parts
of a hologram, although they have information of the whole, will
suffer some resolution deficit.
Holograms

Figure 2 Reproduced from Kasper and Feller, The complete book of
holograms, 1987, pp 4-5.
As seen above in figure 2, the holographic plate records an
interference pattern between the diverged laser light and the
scattered laser light bouncing off the object. The pattern recorded on
the holographic plate is in the holographic domain. All parts of the
holographic plate contain information of the whole. Light bouncing off
each point on the object is distributed (spread out) to every location
on the holographic plate) . Alternatively, the pattern recorded on the
photograph is an image (non-holographic). The image features are
located at particular locations on the photographic plate. Light
scattered off the object (now in the holographic domain) is
transformed to the non-holographic (image) domain by the lens of the
camera (which does an effective inverse Fourier transform) by focusing
the image on the photographic film. For the photograph, there is a
one-to-one mapping between the two-dimensional projection of points on
the object to locations on the photographic plate. Correspondingly,
there is a one-to-all mapping for the holographic plate.

Figure 3 Reproduced from Kasper and Feller, The complete book of
holograms, 1987, pp 4-5.
In the case of the photograph (see figure 3), light is scattered
off the photograph (which is now in the holographic domain) and
becomes incident on the eye which does a transformation (focuses)
which forms an image on the retina. For the holograph, laser light is
shined through the holographic plate (picking up the holographic
information from the plate) and becomes incident on the eye which does
a transformation (focuses) which forms an image on the retina. The
holographic nature of the light incident on the lens is shown in
figure 4.

Figure 4 Diagram expressing the holographic nature of light incident
on the surface of the lens of the eye.
The light scattered from point A is incident at each location of the
lens (likewise for the light scattered off of B. The lens functions to
transform this holographic domain to an image of A and B at the
retina.
The discussion so far has just taken us to the image formed at the
retina. The interesting part of the holonomic brain theory is what
happens next. The focal point of the above discussion is that a lens
does an effective (inverse) Fourier transform on the light incident to
it. The Fourier transform (and inverse Fourier transform) consists of
convolution integrals which mathematically smear or de-smear the
information. For continuous functions, the Fourier transform and
inverse Fourier transform are as follows (for transforms between the
time and frequency domain):

The Fourier transform also has meaning between a spatial domain (for
instance the position in two dimensional space) and spatial frequency.
Mathematically, the two-dimensional spatial Fourier transform is
and the inverse transform is

where x and y are spatial coordinates and a and b are horizontal and
vertical frequencies.
One realization of the Fourier transform is the principle of
diffraction. If you shine coherent light through one point there will
just appear a large white blob on a screen. If coherent light is
shined through two separated points, though, a diffraction pattern
will appear (see figure 5). The orientation of the (sine-wave) grating
is caused by the relative orientation of the two points.

Figure 5
In each figure pair, coherent light shining through the point(s) on
the left would create the (diffraction) pattern seen on the right. The
right hand side of each figure pair represents the Fourier transform
of the left-hand side of the figure pair. Reproduced from Taylor,
Images, 1978, page 27.
Mathematically, the diffraction patterns seen are explained by
taking (two-dimensional) Fourier transform of the points. The
right-hand side of each figure pair is the Fourier transform of the
left-hand side (and visa versa).
If coherent light (or light from a point source) is shined through
two slits, a diffraction pattern can be demonstrated as seen in figure
6. Note a large blob in the middle and smaller blobs tapering off to
either side. The separation and angular position of the spectral blobs
is dependent on the separation and orientation of the slits.

Figure 6
The left hand side of each pair indicates the geometry of the slits.
The right-hand side of each pair shows the optical diffraction
pattern. Reproduced from (Taylor, Images, 1978, pages 42-43).
Figure 7 shows the mathematical Fourier transform of three
different patterns (square-wave grating, checkerboard, and plaid) into
their respective spatial frequency domains. The spectrum of the
square-wave grating has odd numbered harmonics that taper off in
amplitude to each side. Note that the plaid shape is made up of the
addition of vertically and horizontally oriented square-wave gratings.
Similarly, the spectral representation of the plaid is the
superposition of the spectral representation of the vertical
square-wave grating and what the spectrum would be (not shown) for a
horizontal square-wave grating. Pay particular attention to the
dominate four components to the plaid spectrum (the heaviest four dots
towards the center. Now compare those dominate dots to the
corresponding ones in the spectrum of the checkerboard. Note that
there is a 45° rotation. This can be intuitively understood because
you can perceive rows of white and black squares running at the 45
degree orientation for the case of the checkerboard. This fact will
become very important in the physiological experiment to be described
later in the report.

Figure 7
Stimuli and the corresponding Fourier spectrum. (A) square-ware
grating. (B) checkerboard with squares. (C.) checkerboard with
rectangles wider than tall. (D) plaid. Reproduced from De Valois et.
al., 1979, page 485.
Before proceeding, a couple of examples will be shown of the effect
of not using the entire spectral domain in performing the inverse
Fourier transform. This demonstrates the holographic idea of the
"whole" being stored in all the parts. It also shows that
fairly good images can be achieved without taking the full theoretical
transforms. This is important because neural processing isn't infinite
in extent. The brain (because of its finite nature) would only be able
to take a truncated Fourier transform.
When an inverse Fourier transform is taken of smaller and smaller
areas of the spectral domain. the "whole" is always
captured, but the resolution deteriorates. See figure 8.

Figure 8
The right-hand side of each figure pair shows the spectrum. The left
hand side of each figure pair shows the corresponding image after the
inverse transform. Reproduced from (De Valois & De Valois, Spatial
vision, 1988, page 17).
CHAPTER 3 EUCLIDEAN-BASED GEOMETRIC MODEL
The conventional theory is that the main computational event in
neurons is the generation of the action potential. The firing of the
action potential (for a single cell or a network of cells) indicates
the triggering of a particular perception. In the extreme case (the
"grandfather cell") the firing of a single cell can trigger
a certain memory or perception. More typically, though, it would be
the near simultaneous firing of a whole collection of cells in a
network that triggers the perception. The perception would then be
mediated by the action potential's propagation (through the axon) to
other parts of the brain. It would be the integrative emergent
response of "the other parts of the brain" (including
parallel coupling to other sensory modalities) that yields the
sensation of the perception.
For visual perception, there is the following information flow
(Kendel, Principles of Neural Science, page 438)
Retina: cells respond to small circular stimuli
Lateral geniculate nucleus: cells also respond to small circular
stimuli
Primary visual cortex: transforms the concentric receptive field in
at least three ways.
1. Visual field decomposed into short line segments of different
orientation, through orientation columns. Early discrimination of form
and movement.
2. Information about color is processed through "blobs"
which lack orientation selectivity
3. Input from the two eyes is combined through the ocular dominance
columns (one of the steps necessary in depth perception.
Central connections of the visual system are remarkably specific.
Separate regions of the retina project to the lateral geniculate
nucleus in the thalamus in such a way that a complete visual field for
each eye is represented in the nucleus. Different cell types in the
retina project to different targets in the brain stem. Each geniculate
axon terminates in the visual cortex, primarily in layer 4. The cells
in each layer have their own patterns of connections with other
subcortical regions.
Cells in the visual cortex are arranged in into orientation-specific
columns, ocular dominance columns, and blobs. Some of these neurons
have horizontal connections. Information flows both between the layers
and horizontally through each layer. The columnar units seem to
function as elementary computational modules. Each group of cells acts
as a dedicated circuit to process an input and send it on.
CHAPTER 4 HOLONOMIC BRAIN THEORY
Experimental Evidence
Hubel and Wiesel (1959, 1962) described and classified simple and
complex cortical cells. They concluded that both simple and complex
cells responded optimally to bars and edges of a certain orientation.
An alternative view was that each cortical cell might be selective for
a particular portion of the two-dimensional Fourier spectrum (a
certain frequency component at a particular orientation) of the visual
stimulus (Robson, 1975; De Valois, Albrecht & Thorell, 1977). The
issue was raised that a true edge detector would need non-linear
dynamics and it was unclear whether the cortical cells exhibited the
necessary nonlinear dynamics.
The two different views were (1) that the cortical cells function
as non-linear edge detectors or (2) as linear spatial frequency
filters. These two views each have different predictions about how the
cortical cells would respond to a visual stimulus. By making use of
gratings and checkerboards as the visual stimuli, De Valois et. al.,
1979, were able to distinguish between these two possibilities.
Figure 7 (from earlier in the report) shows different patterns
(that can be presented as visual stimuli) and the corresponding
frequency spectrum. Each spectrum here is plotted in polar form where
the distance from center represents the spatial frequency of the
stimulus and the angle (from 0°) represents the phase information or
the orientation of the spatial frequency of the stimulus. The size of
the dots represents amplitude. In rectangular coordinates the spectrum
would be interpreted as frequency components in the vertical and
horizontal directions.
For example, a square-wave grating with vertical bars (see figure
7) would manifest a frequency (repeating pattern) in the horizontal
direction. The spectral depiction of this image would be decomposed
into various frequency components all in the horizontal direction.
This would be plotted (in the representation used here) as dots along
the horizontal axis. A spectral plot of a square-wave grating with
horizontal bars would consist of dots along the vertical axis.
When an animal is presented with the spatial visual field (the
left-hand side of each figure pair) the question can be asked
"are the cortical cells responding to information in the original
spatial domain or information in the frequency (spectral)
domain?". In what representation is the information getting to
the cortical cells? Can an experiment be devised to distinguish
between these two possibilities? For example, is a particular cortical
cell responding to the presence of a line in the visual field or to
the fundamental Fourier component (at a certain orientation) of the
spectrum? This issue was resolved by comparing the response of the
same cortical cell to different visual fields (De Valois et. al.,
1979).
A series of experiments were performed in both cats and monkeys (De
Valois et. al., 1979) to see if the cortical cells responded to
differences in the Fourier spectrums. The first experiment was
designed around the observation that spectral Fourier fundamentals for
the checkerboard were rotated at 45 degrees relative to the Fourier
fundamentals of either the square-wave grating or the plaid (see
figure 7). Vertical square-wave gratings, plaids, and checker-boards
each have vertical edges in the same orientation. Therefor, if a
cortical cell was functioning as an edge detector, the cell should
respond optimally (most number of spikes or action potentials per sec)
to square-wave gratings, plaids, and checkerboards all in the same
orientation. If, however, the cortical cells were responding to the
spectral fundamentals, the cortical cell should respond optimally to a
checkerboard pattern that is rotated 45 degrees relative to either a
square-wave grating or a plaid pattern that was oriented to produce
the optimal response.
In both cats and monkeys, the procedure would be as follows. A
micro-electrode would be inserted into a visual cortical cell to
measure the number of action potentials (spikes) per second. The
optimal stimulus parameters were first determined for the cell. The
receptive field was located and the animal was positioned so that the
receptive field was centered on the scope display. Then by
experimenting with different sine-wave gratings, the optimum
orientation and the optimum spatial frequency for the cell was
determined. The optimum temporal frequency was determined by drifting
the best grating pattern across the respective field at different
rates. If the cortical cell was functioning as a true edge detector,
one would expect the square-wave grating, the checkerboard, and the
plaid to all induce maximal spikes/sec in the cell at the same
orientation. The cortical response to the square-wave grating was
determined with various angular rotations. Then the cortical response
(# spikes/sec) was determined from the checkerboard at various angular
rotations. The visual cortical cells responded optimally to the
checkerboard pattern which was rotated 45 degrees relative to the
square-wave grating that was rotated to produce the optimal response
(see figure 9). This was evidence that the visual cortical cell was
responding to the Fourier fundamentals, not as an edge detector.

Figure 9
Reproduced from De Valois et. al., 1979, page 489.
In another experiment, checkerboards stimuli of different check
dimensions (1/1, 2/1. 0.5/1) were presented (to the animals) for
comparison with the square-wave grating visual stimulus. The altered
(orthogonal) dimension of the checkerboard checks should not matter if
the visual cortical cells are responding to the unaltered edges. If,
on the other hand, the visual cortical cells are responding to the
fundamental Fourier frequency, the different checkerboard patterns
would have to be rotated some to get the maximal spikes/sec from the
cells. Note how the Fourier fundamentals (the biggest dots) are at a
different angle from the center in comparing figure 7B to 7C). It was
indeed found that the different checkerboard patterns had to be
rotated an amount that matched exactly to what would be predicted from
the mathematics of the Fourier transform (the location of the Fourier
fundamentals). When the data was re-plotted with the points rotated
according to the mathematically predicted position of the Fourier
fundamentals, it was found that a very good match existed. This was
further evidence that the visual cortical cell was responding to the
angular location of the Fourier fundamentals and not the edge of the
squares (or grating) seen in the untransformed pattern.
In another experiment, plaid checkerboard patterns with the same
dimensions were presented (with various rotations) as the visual
stimulus to the experimental animals. Again, if the cortical cell was
functioning as an edge detector, it would be predicted that the cell
would respond optimally to the two patters at the same orientation
(when the edges are at the same orientation). It was found, though,
that the cortical cell responded optimally to a checkerboard pattern
that was rotated 45 degrees relative to the orientation of the plaid
pattern (that had been oriented to give an optimal response).
The next batch of experiments were centered around the observation
that the Fourier fundamentals for the checkerboard (with squares of
the same width as the bars of the square-wave grating) were located
farther out (from center) than the Fourier fundamentals for the
square-wave grating. Thus, a test could be done to see whether the
cortical cells were responding to the width (separation between lines)
or to the spatial frequency of the optimally presented pattern. If the
cortical cell was responding to the separation between edges, then the
best match should be for a checkerboard with squares of the same width
as the bars in the square-wave grating. If the cortical cell was
responding to the Fourier fundamentals, then a checkerboard with a
different sized check (or bar width) would induce the optimal
response. The "contrast sensitivity" was defined as that
contrast of the pattern that was necessary to yield a particular
number of spikes/sec for the cortical cell. The control was the
square-wave grating with a bar width (and orientation) that produced
the maximal cortical cell response. The experimental bar width
(yielding the best response for the optimal orientation) for the
checkerboard matched what was predicted from the Fourier mathematics
(De Valois et. al., 1979). This provided more evidence that the visual
cortical cell was responding to the Fourier fundamental and not the
edges ( or distance between the edges) of the visual stimuli.
In another experiment, the relative check dimensions were changed
for the checkerboard patterns (2/1, 1.1, 0.5/1 ratios). Note from
figure 7 that as one dimension of the check is changed, the distance
(from center) of the Fourier fundamentals changes. It could then be
determined what width (given a certain ratio) produced the best result
(when oriented optimally). If the visual cortical cells were
responding to the check width, then the different height/width ratios
shouldn't influence the cell's response. If, the cell was responding
to the Fourier fundamentals, then it should respond optimally to
different check widths when the height/width ratio changes. It was
found that the cortical cell responded optimally to checkerboard
patterns of different widths and that these widths matched what was
predicted from the Fourier mathematics De Valois et. al., 1979). When
the data was plotted according to the theoretical prediction, the
cortical cell was shown to be responding to the spatial frequency (the
distance from center of the Fourier fundamental) for the various
optimally oriented patterns. This was further evidence that the
cortical cells were responding to the Fourier transform of the
presented visual stimuli.
All of these experiments were repeated for multiple visual cortical
cells in both the cat and monkey yielding similar results (data not
shown in this report).
The next set of experiments examined whether cortical cells could
be found that were sensitive to higher harmonic components of the
Fourier spectrum. If so, then this would be powerful evidence that
these cortical cells are acting like spatial-frequency filters (and
not as edge and bar detectors). The higher spectral harmonics of the
square-wave grating are at the same orientation as the fundamental
frequency but the higher harmonics of the checkerboard are at other
orientations (see figure 7). If a cortical cell exhibits sufficiently
narrow spatial tuning, it could potentially respond separately to the
fundamental and the third harmonics of patterns. For instance, imagine
a square-wave grating with more narrow bars such that the fundamental
frequency falls on what was the third harmonic for a square-wave
grating with wider bars. A cortical cell sensitive to this spectral
position, would respond to either stimulus (and the stimuli would be
presented at the same orientation). For the checkerboard, the
situation would be a little different. A smaller sized checkerboard
pattern sufficient to produce a Fourier fundamental at the same
frequency location as the third harmonic (that a larger sized
checkerboard pattern would produce) would have to be rotated some for
the optimal response (to get the angle of the fundamental to fall on
where the third harmonic would be for the other pattern).
It was demonstrated that a cortical cell (responding to a
square-wave grating of a certain frequency and orientation) would also
respond optimally to a square-wave grating with bar widths three times
the size (which would be one third the spatial frequency) with the
same orientation. The Fourier fundamental of the grating with the more
narrow bars fell on the third harmonic of the grating with the wider
bars. It was also demonstrated that the same cortical cell responding
to a sine-wave grating (optimally at a certain frequency and
orientation) would not respond to a sine-wave grating of 1/3 that
frequency at the same orientation (remember that there are no
harmonics for a sine wave).
In order for the cortical cell to optimally respond, a checkerboard
pattern with check size of a certain size had to be rotated relative
to the optimal rotational orientation of a checkerboard with checks
that were three times larger producing the optimal response for the
same cortical cell. This observed rotation matched the theoretical
predicted rotation from the Fourier mathematics (De Valois et. al.,
1979).
Similar experiments have been performed with the rat somatosensory
system (Pribram, 1994) where the cortical cells were also found to
respond to spectral information.
Other Aspects of the holonomic theory
Pribram says that both time and spectral information are
simultaneously stored in the brain. He also draws attention to a limit
with which both spectral and time values can be concurrently
determined in any measurement (Pribram, 1991). This uncertainty
describes a fundamental minimum defined by Gabor in 1946 (the inventor
of the hologram) as a quantum of information. Dendritic
microprocessing is conceived (by Pribram) to take advantage of this
uncertainty relation to achieve optimal information processing.
Pribram then says that the brain operates as a "dissipative
structure" where the brain continually self-organizes to minimize
this uncertainty. The next few sections will attempt to explain the
concept of the "uncertainty principle" and the concept of
"dissipative structures" that self-organize.
The Uncertainty Principle
Quantum Physics
In quantum physics, the uncertainty principle can be described in the
following way (paraphrased from Pagels, 1982): Consider that you have
a device that can simultaneously measure the position and momentum of
a single electron. Every time you push a button, the device displays
numerical values for the position and momentum. Although, each time
you press the button, you will get slightly different measurements for
the momentum and position. If enough measurements are taken, then a
statistical analysis can be performed. Heisenberg defined the term
delta q as indicating the spread or uncertainty of the position
measurements around some average value and delta p as indicating the
spread or uncertainty of the momentum measurements around some average
value (for the series of measurements). He then found that (delta
q)x(delta p)>=h where h is Plank's constant. For a series of
measurements, the positions can be expressed as an average +/- some
uncertainty. Likewise for the momentum. No matter how good one makes a
quantum measuring device, the products of the uncertainties can never
be less than Planks constant. For example, if you could build a
measuring device that exactly determined the position (where delta q =
0) then you would not be able to determine anything about the momentum
(delta p = infinity). There is a similar uncertainty relation for the
energy of a particle and the elapsed time. For a series of
measurements, the product of the uncertainty of the energy (delta E)
and the uncertainty of the elapsed time is always greater or equal to
Planks constant. (delta E)x(delta t)>=h.
Communication theory
In communication theory, a variation on the uncertainty principle also
holds (Gabor, 1946). The measurement of the frequency can be made with
arbitrary precision. Likewise, the measurement of the time of
occurrence can be made with arbitrary precision. But there is a limit
to the precision when these measurements are taken simultaneously. One
can exactly measure either the frequency (of for example a tone) or
the time (of occurrence) but not both at the same time. For instance,
if the time of occurrence were known (indicating an impulse function)
there would be frequency components all up and down the spectrum. If,
on the other hand, the frequency information was exactly known, one
would not know any information about when it occurred. A single peak
(or peak pair if you consider the corresponding negative frequency) in
the spectrum implies that the tone has infinite extent in the time
domain. Analogously to the quantum uncertainty principle, when
frequency and temporal measurements are made simultaneously, there is
a limit to the precision possible. Pribram claims that the brain
functions as a dissipative structure to seek to decrease this
uncertainty in the direction of its theoretical limit.
Dissipative Structures
The second law of thermodynamics holds that the entropy always
increases in any isolated system (figure 10). This simply means that
if something is left to itself, it will move towards equilibrium...it
will move towards maximal disorder...its internal energy state will
tend to be minimized. There has not been, to date, any confirmed
observation that this law is invalid.

Figure 10
An isolated system can itself be divided into a subsystem that is
open to energy flow and the subsystem's environment (see figure 11).
As such, the whole combined isolated system still obeys the second law
of thermodynamics, but it is possible that the subsystem can
experience a decrease in entropy at the expense of its environment.

Figure 11
The entropy increase in the "sub-system environment" is
guaranteed (by the second law) to more than offset the entropy
decrease in the subsystem. Also note that the sub-system can only be
maintained away from equilibrium as long as there is usable energy in
its environment. When the environmental entropy is maximized (no
usable energy), the subsystem is guaranteed to itself proceed to
equilibrium.
There is a special class of such subsystems (as described above)
where the subsystem's organization comes exclusively from processes
that occur within the sub-system's boundaries. This class of
subsystems was labeled "dissipative structures" by I.
Prigogine, 1984 (who won the Nobel price for his work). Pribram
believes the brain to be such a "dissipative structure".
One way of modeling a structure that goes to equilibrium is to
minimize a mathematical expression for the internal energy (which is
the same as maximizing an expression for the entropy). This is called
the lest action principle. This would not be appropriate, though, for
a "dissipative structure" since it is not going towards
equilibrium. "Dissipative structures" self-organize around a
different "least action principle". In the holonomic brain
theory, Pribram has the entropy being minimized (which maximizes the
amount of information possible to store) as the "least action
principle". Thus, the system (the brain) self-organizes such that
more and more information can be stored.
In Hopfield networks and the Boltzmann engine (which are computer
models of neural processing), computations proceed in terms of
attaining energy minima. In the holonomic brain theory, computations
proceed in terms of attaining a minimum amount of entropy and therefor
a maximum amount of information. In the Boltzmann formulation the
principle of least action leads to a space-time equilibrium state of
least energy. In the holonomic brain theory, Pribram describes the
principle of least action as leading to maximizing the amount of
information (minimizing the entropy).
Independently, (in unrelated work) Schneider and Kay (1994) have
proposed a variation on the second law of thermodynamics which may be
applicable to Pribram's holonomic theory.
"The thermodynamic principle which governs systems is that as
they are moved away from equilibrium, they will utilize all avenues
available to counter the applied gradient. As the applied gradients
increase, so does the system's ability to oppose movement from
equilibrium".
It would be interesting to see if there is a connection between the
work of Schneider and Kay and Pribram.
The holonomic brain theory maintains that the brain is continuously
engaged in correlation processes. This is how we make associations
(how the senses are integrated). There is an obvious computational
advantage for the brain storing sensory information (and perceptions)
in the spectral (or holographic) domain as opposed to the brain
directly storing individual features and characteristics.
The holonomic brain theory claims that the act of
"re-membering" or thinking is concurrent with the taking of
the inverse of something like the Fourier transform. The action of the
inverse transform (like in the laser shining on the optical hologram)
allows us to re-experience to some degree a previous perception. This
is what constitutes a memory.
CHAPTER 5 CONCLUSIONS
General Comments
The medium of the optical holography, the silver grains on the
photographic film, encodes the Fourier coefficients. In the holonomic
brain theory, the Fourier coefficients are stored as the micro process
of polarizations and depolarizations occurring in the dendritic
networks.
Both Pribram's theory and the more conventional theory have the brain
divided up into various functioning communicating modules. One main
difference is in how the information is stored in these brain modules.
For example, in the case of vision, the conventional theory has
specific features stored in certain dedicated cells. These different
sub-modules then have parallel pathways to other modules that produce
the combined visual experience. This would be somewhat analogous to a
computer performing signal processing directly on an image. For
example, dedicated circuitry for edge detection would interface with
other circuitry for other features like color. Every feature of the
image gets stored (or processed) in different dedicated
"circuitry". These "circuits" then have parallel
pathways to other brain regions in which the collective subjective
experience of the perception is formed.
The holonomic theory (for the example of vision) summarizes
evidence that the image formed on the retina is transformed to a
holographic (or spectral) domain. The information in this spectral
"holographic" domain is distributed over an area of the
brain (a certain collection of cells) by the polarization of the
various synaptic junctions in the dendritic structures. At this point,
there is no longer a localized image stored in the brain. Correlations
and associations can then be achieved by other parts of the brain
projecting to these same cells. Conscious awareness (and memory) is
the byproduct of the transformation back again from the spectral
holonomic domain back to the "image" domain. Possibly the
most radical part of the holonomic theory is Pribram's claim that a
"receiver" is not necessary to "view" the result
of the transformation (from spectral holographic to
"image"). He claims that the process of transformation is
what we "experience". Memory is a form of re-experiencing or
re-constructing the initial sensory sensation.
Conventional neuro-physiology effectively pushes back the line
between observer and what is observed (between subject and object). In
signal processing, there always needs to be an end-user to view the
processed or transformed signal. At best, conventional neuro-science
leaves until later the ultimate explanation of the observer. Who would
bet their grant money (career) on being able to answer this question
in a couple of years? Aspects of Pribram's holonomic brain theory
attempts to address this question.
The conventional view is that the brain is a computational device.
There is a growing body of literature, though, that shows that there
are severe limitations to computation (Penrose, 1994; Rosen, 1991;
Kampis, 1991; Pattee, 1995). For instance, Penrose uses a variation of
the "halting problem" to show that the mind cannot be an
algorithmic process. Rosen argues that computation (or simulation) is
an inaccurate representation of the natural causes that are in place
in nature. Kampis shows that the informational content of an
algorithmic process is fixed at the beginning and no "new"
information can be brought forward. Pattee argues that the complete
separation of initial conditions and equations of motion necessary in
a computation may only be a special case in nature. Pattee argues that
systems that can make their own measuring devices can affect what they
see and have "semantic closure".
It is possible that the brain transcends computational behavior. If
this is the case, then it will be very interesting to see what aspects
of Pribram's holonomic theory are in collaboration with these
non-computable ideas.
Conclusions
Karl Pribram's holonomic brain theory weaves several concepts together
in forming the holonomic brain theory. A partial list is the
following:
1. The apparent spectral frequency filtering aspect of cortical
cells
2. The relationship between Fourier transforms and holograms
3. The fact that selective brain damage doesn't necessarily erase
specific memories
4. The computational advantage to performing correlations in the
spectral domain.
5. His idea of conscious experience being concurrent with the brain
performing these Fourier-like transformations (which simultaneously
correlate a perception with other previously stored perceptions). He
believes that conscious experience is the act of correlation itself
and this correlation occurs in the dendritic structures by the
summation of the polarizations (and depolarizations) through the
processes in the dendritic networks.
6. The brain is a "dissipative structure" and
self-organizes around a least-action principle of minimizing a certain
uncertainty relation.
Most conventional experimental neurophysiologists are content just to
gather neurological data independent from any global theory of the
brain/mind and leave a theory of the brain to future generations. As
such, Karl Pribram is not referenced in many of the major neuro
physiology textbooks (such as Principles of neural science by Kandel,
Schwartz, and Jessell, 1991). This is unfortunate because it helps to
have a theory in asking important experimental questions. With a
different theory comes different questions which can lead to new and
different experiments that can bring forth novel information.
Hopefully, Pribram's ideas (or variations on them) will eventually
find their way into the consciousness of the conventional
neurophysiologist (and appear in most textbooks) once the current
fascination with molecular biology runs its course. Then the attention
of physiologists may again be directed back toward a system's
organization and away from simply analyzing its parts.
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