This book was simultaneously written for
a general audience and for the scientific mind. It is
basically a popular science book, but contains ideas I have
developed over the last 10 years.
Here is what
I believe the book offers.
1. It
explains in terms of the components of the brain (namely neurons,
synapses and neural networks) how memory is stored, retrieved and
processed in the brain, and why neural memory is so different to
computer memory. I also discuss how the brain develops
after birth, and why I believe that the brain does indeed forget.
I am amused that some psychologists are only recently starting to
think that the brain does not keep a trace of every experience.
[See recent issues of New Scientist.] Neural network models
suggest that memories are constantly competing with each other,
they change with time and some memories are simply displaced.
Memories are also lost as neurotransmitter stores (where memory
is actually stored) decay with time.
2. It
explains how the brain generates new ideas and creativity. In
the brain, memories are stored in a distributed and overlapping
fashion, sharing neurons and synapses, quite unlike the way
memory is stored in a computer. A consequence of this
common storage arrangement is that the brain generates its own
'memory' states, called 'spurious memories'. These states
have been observed in mathematical models and there is every
reason that they should also be present in the brain. Spurious
memories are generally comprised of combinations of features of
stored memories. I have suggested that these spurious
memories are the basis of creativity, and that they allow us to
adapt to an ever-changing environment. Spurious memories
are actually also necessary for new learning. This is a
major shift to previous thinking, as most researchers were
interested in finding ways to eliminate them from neural systems
(hence their name) to improve the retrieval of stored memory, but
the brain is not just a recording device. I am saying that
spurious memories may be the most important brain states, as they
enable the brain to function autonomously, to adapt, to be
creative, and to learn. Albert Einstein once said,
"imagination is more important than knowledge". That
may be true, but if I am correct this should be supplemented with
the fact that imagination is based on knowledge. This is
because new ideas (spurious memories) are based on known
information or memories. You would hardly get an idea about
quantum field theory if you knew nothing about it, and in any
case it would not mean much if you knew nothing about it.
3. It
explains how the brain functions autonomously, without any need
for central control. This is achieved by learning spurious
memories. Without them the brain would only be able to recall
what was stored in it. Neural network researchers normally store
memories in neural systems by adjusting the links between neurons
by hand, but there is no one that does this in the brain. The
brain accomplishes this by itself and to my mind spurious
memories are the way it does it. This is interesting
because it means that whatever you learn is in a sense already
stored in your brain. When you come to learn something new,
a weak spurious memory (that already exists in your brain) is
entrenched so as to become a strong stored memory. This
idea has serious implications for building real artificial
intelligence systems. Most AI researchers are still looking
at models with a central controller. In my model there is no need
for central control.
4. It
explores what the brain may be doing during rapid-eye-movement
(REM) sleep, the phase of sleep normally associated with
dreaming, incorporating all the neurobiological evidence (such as
what exactly is going on in the brain when we dream). I
also address the function of dream sleep and why it is that we
and all other mammals have evolved to dream. The function
of dreaming is one of the main unsolved puzzles in systems
neurobiology. My theory on the function of dream sleep is
based on an idea first put forward by Nobel Laureate Francis
Crick (DNA) and Graeme Mitchison, but with a twist. They
suggested that we unlearn or reverse-learn when we dream. A
consequence of this is that we forget unwanted memories and
reduce obsession by dreaming. I agrees with that, but Crick
and Mitchison also suggested that we dream to reduce parasitic or
spurious memories. I have found however (by simulation
experiments on neurobiologically realistic neural networks) that
reverse-learning actually increases the proportion of spurious
memories. This is great news for my theory that spurious
memories are important. My theory is that we dream to
generate roughness (spurious memories) in our memory space so we
are better disposed to learn and be more adaptive in a new and
ever-changing environment. Dreaming also aids creativity.
Without enough REM sleep our learning capacity is diminished, we
are unable to think, adapt and be creative. In addition to
the above, I also review ALL other theories on the function of
REM/dream sleep, and explain for example why Freud had it all
wrong. Freud was not aware for example that babies and
children have so much more REM sleep than adults. What
psychological need could an infant have for so much dream sleep?
5. It
presents my theory on the cause (and trigger!) of sudden infant
death syndrome. I assert that my theory is the only theory
that fits in with all of the known facts about SIDS. Basically,
the theory goes along the following lines. Lucid dream
research has shown that we try to act out our dreams, as much as
is possible. When a researcher dreamt that he was swimming
underwater, he really held his breath while he was asleep. We
also dream about our own personal memories. Adults dream
for about 2 hours each night, whereas a baby can dream for up to
8 hours a day, but what could a little baby be dreaming about?
What memories can it possibly have? I suggest that it could
dream of being back in the womb where it did not have to breathe,
because the mother supplied it oxygen through the blood, and just
as the researcher held his breath while dreaming he was swimming
underwater, the baby may stop breathing. This theory
explains why all the neurological alarms are not activated and
why there are no physical signs of death (no struggle). Remember
that a SIDS death is only diagnosed after every other cause of
death is excluded. The first and only symptom of SIDS is
death. Note, I am also saying that the reason why medical
researcher have not made an advances in understanding SIDS is
because it is in the mind of the infant. My theory explains
all sorts of things, such as why the risk is higher in the prone
position, why it is more prevalent in colder climates, why dummy
(pacifier) sucking helps but thumb-sucking is a risk, etc. I
also suggest how the incidence of SIDS can be reduced further by
making the environment of the sleeping infant less womb-like.
This aspect of the book was recently reviewed in New Scientist
(12 April 2003). See http://www.newscientist.com/opinion/opbooks.jsp?id=ns23903.
6. Among many other things, I have even come up with an explanation of déjà vu, based on the confusion of spurious memories with real memories. Normally the brain takes much longer to converge to spurious memories (as observed in neural network models). Déjà vu results when for some reason the brain converges to a spurious memory quickly giving us the impression that we know that 'memory', whereas it has not been formally learnt as yet, and is unknown to us.