Daniel
Goleman:
History tells
us that, with
every paradigm
shift in science,
a new frontier
of legitimate
investigation
opens. And
from that
new frontier
come answers
to questions
the old paradigm
did not allow
to be asked.
It seems to
me you're
posing questions
that have
not been allowed
before a precarious
position.
Karl
Pribram:
Let me tell
you how I
got into the
holographic
story. First,
though, I
want to make
it clear that
this is a
development
of theory
and is fairly
independent
of the day
today laboratory
research program
that engages
me. The theory
is largely
based on the
research of
others. Nonetheless,
because I
am actively
doing brain
research,
I have had
the opportunity
of at least
checking for
myself the
essential
results on
which it is
based.
Back
in the 1950s,
people dealing
with the brain
and those
dealing with
mental processes
weren't together.
Psychologists,
who were supposed
to be dealing
with mental
processes,
by and large
at that time
thought “mind"
was a dirty
word; they
were dealing
with behavior.
People who
studied the
brain were
in neurophysiology.
I wondered
why people
who were interested
in behavior
weren't also
interested
in brain function.
The answer
always was
that we simply
didn't know
enough about
the brain-
a fair evaluation
of the state
of the art.
For
one thing,
brain science
was plagued
by some classic,
unsolved mysteries.
One was the
puzzle of
memory loss.
More exactly,
why was that
any given
discrete memory
would not
be lost after
brain injury?
If a person
has a stroke,
and half his
in is destroyed,
he doesn't
come home
and recognize
only half
his family.
It doesn't
work that
way. Either
memory is
destroyed
completely
or nothing
is lost. There's
no correspondence
between how
much tissue
is damaged
and how much
memory is
lost.
Experiments
had been done
showing that
just 2 percent
of the fibers
in a particular
system would
retain that
system's functions.
There's an
amazing amount
of redundancy
in the brain.
Imagine if
98 percent
of your kidneys
were gone,
but the other
2 percent
worked so
well you couldn't
d anything
wrong at all.
The brains
spare reserve
for memory
is fantastic.
And we couldn't
explain it.
Thus,
for over half
a century,
physiologists
have searched
for an “engram”—a
change in
brain cells
that marks
a memory trace.
They've never
found one.
Memory seems
to be distributed
throughout
the brain,
located in
no particular
part.
Goleman:
What are the
other classic
puzzles of
brain science?
Pribram:
One, there's
the constancy
problem, the
question of
how we can
recognize
an object
regardless
of distance
or the perspective
from which
it is viewed.
No matter
where you
sit in this
room I can
recognize
you as Dan
Goleman. You
can sit far
away or very
near, and
I don't look
at you and
think that
your head
has become
swollen or
shrunk. Your
head looks
a reasonable
size no matter
where you
are. Yet the
question raised
is: how does
a hard wired
brain, in
which connections
between parts
are fixed,
allow perceptual
flexibility?
Then
there's a
similar puzzle
in the motor
system, in
which skills
can be transferred
from one limb
to another...I'm
right handed,
but if I try,
I can write
with my left
hand. Or even
by holding
a pencil in
my teeth.
Next time
you are at
the beach,
try to write
in the sand
with your
left big toe.
The puzzle
is that the
part of the
brain that
controls the
left hand,
or the teeth,
or the big
toe has never
written anything
before. How
does that
particular
group of brain
cells process
information
about writing?
Something
has happened
that takes
memory of
my learning
how to write
and distributes
it to places
in the brain
where it's
never been
called on
before. There
was, until
.recently,
no good explanation
for the brain's
ability to
do that.
Goleman:
Where have
puzzles like
that led you?
Pribram:
Ideas started
to come together
in the mid
60s. A major
factor was
the invention
of the hologram.
A hologram
produces a
three dimensional
image from
a photographic
film on which
the interference
pattern of
light waves
reflected
from an object
or scene has
been recorded.
When the film
is illuminated,
an image of
the object
is produced.
Goleman:
What does
any of this
have to do
with the brain?
Pribram:
Sir John Eccles
mentioned
in an article
several years
ago that "synaptic
potentials"
-the electrical
exchanges
between brain
cells -don't
occur alone.
Every nerve
branches,
and when the
electrical
message goes
down the branches
a ripple,
or a wave
front is formed.
When other
wave fronts
come to the
same, location
from other
directions,
the wave fronts
intersect
and set up
an interference
pattern. It's
somewhat like
the meeting
of ripples
that form
around two
pebbles thrown
into a pond.
It
seemed plausible
to me that
if there are
interfering
wave fronts
in the brain,
those fronts
might have
the same properties
as a hologram.
Both holograms
and brain
tissue can
be cut up
without removing
their image-processing
capabilities.
Holograms
are resistant
to damage-
like memory
in the brain.
The persistent
puzzle of
a distributed
memory might
be solved.
The brain
had to behave,
in part, like
a hologram.
Goleman:
The puzzle
couldn't be
solved without
the hologram.
Pribram:
Right. We'd
been searching
for some organizational
principle
that would
allow for
the basic
facts of perceptual
constancy,
transfer of
learning,
and the elusiveness
of memory
in the brain.
Suddenly,
this principle
was presented
to us in the
hologram.
Goleman:
So that was
the single
organizing
principle
that allowed
for some understanding
of all those
things you
already knew
to be both
true and puzzling
about the
brain.
Pribram:
Yes. Best
of all, we
didn't have
to conjure
up a mechanism
in the brain;
the hologram
was there
all the time
in the wave
front nature
of brain cell
connectivity.
We simply
hadn't had
the wit to
realize it.
Even Eccles,
who pointed
to the wave
phenomenon
in the first
place, has
more recently
gone back
to emphasizing
the nerve
impulse aspects
of brain functioning.
Goleman:
But this is
all theory.
Do you have
any data to
back it up?
Pribram:
Once we saw
where to look,
it became
clear that
one test that
could be readily
made was whether
the behavior
of single
cells in,
for instance,
the visual
system, would
obey the mathematical
laws that
comprise a
hologram.
The physical
hologram stores
the interference
patterns of
light reflected
from objects.
The question
became, therefore,
whether there
are cells
in the brain
that respond
to the interference
patterns of
sensory input.
In short,
do they act
as frequency
analyzers
-that is,
do the cells
resonate to
different
frequencies?
Goleman:
Which is to
say, that
when the environment
presents a
certain frequency,
a specific
group of cells
in the brain
resonates
to that frequency
and not to
others?
Pribram:
Right. A century
ago, Georg
Simon Ohm
suggested
that brain
cells in the
auditory system
act as frequency
analyzers
for sounds.
Ohm is also
responsible
for Ohm's
Law in electricity,
which relates
to voltage,
amperage,
and resistance.
Hermann. von
Helmholtz
followed up
Ohms suggestions
and, for many
years, the
auditory system
was considered
to be something
like a piano
keyboard.
Then Georg
von Bekesy
showed that
the cochlea
of the inner
ear operated
more along
the lines
of a string
than a keyboard.
He also showed
that not only
the ear, but
the skin as
well acts
like a string:
it is sensitive
to vibrations
and their
frequencies
in such away
that, for
example, fine
tuning forks
vibrating
on the forearm
are perceived
as a simple
point of vibration
when their
phases of
vibration
are properly
adjusted.
In
our laboratory,
we showed
that only
a single response
is produced
in the brain
cortex under
those conditions.
A further
inference
than can now
be readily
tested quantitatively
is that the
brain cells
respond in
terms of this
interaction
of the response
and the frequencies
of the tuning
forks.
Goleman:
How so? What
are the mathematics
involved?
Pribram:
It's called
a Fourier
analysis,
and is a form
of calculus
that transforms
a complex
pattern into
its component
sine waves.
Helmholtz
showed that
this kind
of analysis
could explain
the functioning
of the auditory
system. Then
an entirely
different
line of research,
done in Russia
by N. Bernstein
in the 1930s,
showed that
the same type
of analysis
fit the motor
system. We
didn't hear
of that work
until the
1960s, because
Bernstein's
book, The
Coordination
and Regulation
o/ Movements
[Pergamon
Press), wasn't
translated
until 1967.
Goleman:
What did Bernstein
do?
Pribram:
It was really
fascinating.
He dressed
people in
black leotards
and took movies
of them against
black backgrounds.
Black on black.
Except that
he painted
white dots
on their joints
-elbows, knees,
and so on.
Then he had
them do things
like hammer
nails, or
jump up and
down on platforms
that were
on springs.
Of course,
all that his
movies showed
were white
dots moving
up and down
along the
film, creating
wave forms.
He
did a frequency
analysis at
the wave forms.
The mathematics
he used were
Fourier's.
With that
analysis,
he was able
to predict
within a few
millimeters
where the
next step
in the sequence
would fall.
Now,
I read Bernstein's
work and saw
that he was
using the
same mathematics
for motor
activity that
Ohm had used
to describe
the auditory
system. And
that was the
same mathematical
principle
that Gabor
had used to
invent the
hologram.
So I thought,
"If Bernstein
can do a Fourier
analysis on
these movements,
why can't
his brain
do it? And
if his brain
can do it,
mine can,
too, and perhaps
this is the
way everyone’s
brain analyzes
movements
into their
"frequency
components.”
Goleman:
So you have
the same organizing
principle
in the auditory,
somatosensory,
and the somatomotor
systems.
Pribram:
That left
the visual
system. In
1968 or so,
I got a note
from Fergus
Campbell at
Cambridge
University.
His group
had just shown
that the visual
system also
worked as
a frequency
analyzer for
patterns.
The significance
of his discovery
has still
not filtered
down to textbooks,
which consider
cells in the
visual system
as "feature
detectors,"
cells that
are selective
of highly
specific features,
such as lines
and comers.
A classic
study had
shown that
cells in a
frog's visual
system fired
only in response
to buglike
movements.
From such
studies, it
was concluded
that all of
the brain's
involvement
in perception
was due to
the fact that
particular
cells detected
particular
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