mind> brain p1
The human mind~brain is just a particular example of a general
phenomenon - a cognitive or adaptive system. But it is also of
course the most complex or hierarchically involuted example we know. So
let's spend some time thinking about how brains can have minds.
The following three introductory pages sketch the basic story.
Then there are abundant links to more detailed material.
first meet your brain
The human brain seems impossibly complex. It contains 100
billion neurons – individual brain cells. Each neuron can
make anything from a thousand to several hundred thousand synaptic
connections. So your brain has something like 1000 trillion or 1015
connections. And every connection is meaningful. It has been shaped by
your personal history.
This is only scratching the surface of the brain’s
complexity. Synaptic connections come in many forms, using different
messenger molecules to evoke different responses. And neurons
themselves only make up a fraction of the brain. The brain has glial
cells – ordinary cells that do support, transport, growth and
housekeeping jobs. There are about 50 glial cells to every neuron. Then
nearly half the brain is made up of white matter – the fat
insulated trunk cabling that is used to carry signals about the brain.
If the white matter from a single human brain were unravelled, it would
form a strand long enough to wrap twice around the globe.
So imagine all this – the neurons, their connections, the
support cells, the cabling – balled up inside your skull. And
when it is switched on, it becomes conscious. The gelatinous circuitry
shivers with a traffic of thoughts, impressions, urges, conflicts,
worries, curiosities and intentions.
Well actually we have already made a crucial mistake in talking about
the brain. While it is usual to think of the brain as the wrinkled lump
filling your skull, in fact it penetrates your whole body.
The brain itself has the tail of the spinal cord. Then from the spinal
cord sprouts a maze of nerves that reaches even the remotest corners of
the body, catching it in a knowing embrace. Everything from the beating
of the heart, the pulsing of the gut, the production of new blood
cells, right down to the raising of individual hairs on our arm when we
get a fright, is controlled by the nervous system, and so ultimately
the brain. And even where the nervous system does not act directly, it
can control by secreting hormone messengers which diffuse through the
blood and body tissues. No organ or individual cell is beyond its
reach.
So try to rip your brain out of your skull and it will come trailing a
five or six foot long tangle of uprooted fibres and dribbling nerve
endings. If consciousness is the product of “brain
activity”, then it is about more than what takes place inside
your head. As psychologists like to say, the mind is embedded. Your
whole body sings with knowingness or cognition.
why are we not zombies?
Of course the big question is why does all this living machinery
actually light up with something so surprising as consciousness? It
seems perfectly plausible that you could have all the pulsing and
twitching of a network of nerves and then – nothing. A
zombie, an
automaton, that might act out in a robotic fashion yet have
no inner experience.
The reason why consciousness comes as a causal surprise is because
consciousness gets axiomatically excluded right at the start of any
mechanical account of the world. Mechanicalism tries to build
everything from “material” – mindless
substance or stuff. There is then no easy way for mindfulness to get
back in.
Let’s be a little more precise here. The mechanical view is
actually forced into a dichotomy. It is clear that the world has
localised substances with their particular properties – atoms
in other words. Then atoms get woven into forms and out of complex
arrangements certain new global properties may
“emerge”.
So the mechanical approach, which treats substance as causally
fundamental, form as the resultant outcome, is left with two possible
explanations for consciousness. Either awareness is somehow an aspect
of substance itself, a localised property, or it is an emergent
property, something that pops out at the top once a suitable set of
materials have been arranged into a particular form.
But either way, there is no causal here-to-there, no chain of events
that causes consciousness (and without which, consciousness would have
failed to occur).
For example, if we take consciousness to be a basic property of matter
– perhaps a soul-stuff, a life-force, a quantum resonance, a
dilute field that pervades all reality but which somehow becomes
concentrated in the elaborate collecting circuits of a brain structure
– then it just exists as a particular property of the
universe with no further explanation.
But equally, if consciousness is an emergent property – a new
quality that pops out at the top just like liquidity pops out when you
gather enough H2O molecules under the right
conditions – then
there is still a problem. Or at least most consciousness theorists feel
there is still a problem.
They say there is nothing we know about the organisation of the brain
that seems to demand that consciousness should pop out. Again, it is no
surprise that a complex machine would do some complicated processing of
information. But there is nothing to explain a step from zombie-dom to
an inner light of awareness. There is no causal link that says the
material world must generate an immaterial state of sentience.
The trouble is that mechanicalism always wants to treat consciousness
as something particular and located. It is either a particular property
of the world, some kind of substance, or it is a particular kind of
form. Something about the arrangement of atoms, or neural networks, in
our heads creates awareness as a particular (now emergent) property.
Organicism approaches the problem of the conscious brain quite
differently. It is no surprise that the brain~mind system involves a
separation towards two apparently unlike extremes – the
asymmetry of brute substance and knowing form. And consciousness as
such does not need to be reduced to the particular property of some
substance or left hanging as the somehow emergent property of a lot of
substance. Instead, as a particular, it can be reduced to the general
that is knowing form – mindfulness - in its most universal
sense.
the humble tumbling bacterium
The ultimate goal is a general theory of knowing form
– a
model of the global scale of existence, the upper bound, which can act
with a downward causal constraint. A mind that can control. So
let’s start by considering life as a kind of mindfulness.
Life on Earth began some three and a half billion years ago with simple
algae, bacteria and other single cell organisms. These primitive
creatures had no nervous systems let alone brains. But they did need to
know something about their worlds and then how to respond accordingly.
A bacterium – like E. coli, for example, which colonises the
human gut in great numbers – swims along, driven by the
anti-clockwise cork-screw paddling of its hair-like flagella, on the
lookout for food. Lining its surface are receptors, large protein
structures, that can scent sugars like galactose, or amino acids such
as aspartate. They do this by have binding sites that physically lock
onto the target molecules. And when they snare a sample, this causes
shape changes that then trigger a cascade of chemical signals back
though the bacterium to the flagella.
While the receptors are picking up traces of food, the instruction to
the flagella is to keep rotating anti-clockwise. But if the
concentrations start to fall off, then the flagella are told to
reverse. This sends E. coli into a random tumbling spin until the scent
begins to pick up again, at which point straight-line swimming can
resume towards the source of the food.
I particularly like this example because it is such a perfect example
of an asymmetric dichotomy. Anti-clockwork flagella and E. coli powers
along in a straight purposeful line. Clockwork flagella and it tumbles
randomly through all possible orientations. It is not just a change of
direction but an asymmetrical way of moving – local
directness versus global confusion.
Anyway, cleverly the same receptors proteins can also lock onto
substances E. coli wants to avoid like fatty acids. But with these, the
opposite response is triggered. Meeting increasing concentrations of a
fatty acid cause it to tumble in search of an escape route.
Of course, to be able to sense changing concentrations of either a
repellent or attractant, the receptor proteins need a memory. Binding
causes alterations in their internal shape so that for some seconds
afterwards they become more excited by further traces of a molecule.
Their signals to the flagella become more enthusiastic. This way, E.
coli can tell whether it is moving towards or away from concentrations
of food or toxins.
Here, in a nutshell, we have the reason for any kind of brain, any
level of sentience. Brains exist to optimise behaviour. They are there
to sense the current state of the world and direct us to react in ways
that maximise our chances of survival and reproduction.
Consciousness is often treated as though it were essentially a passive
state of contemplation. For some vague reason, evolution equipped us
with the luxury of being able to appreciate the wonder of colours, the
beauty of form, the bliss of scents. But this is quite wrong.
Consciousness is about seeing through to the particular aspects of the
world that demand a response. Brains exist to turn inputs into outputs
with the greatest possible speed and effectiveness. Brains are for
action and ultimately control over the world.
evidence of mindfulness
We have started with the simplest of lifeforms and already we
have
found mindfulness – and dichotomisation. It is common to
think that there are kinds of life with minds and other kinds that
don’t have minds. A bacterium for example is widely agreed to
be living, but no-one would want to suggest it is conscious. However I
want to argue that any form of life is indeed a form of mind, or at
least mindfulness (which is the more general idea).
This should not be that controversial. To be alive is to be able to
respond and control – both to an inner world of metabolism
and an outer world of threats and opportunities. A bacterium does not
even have a brain. But it still needs something like a brain. It
needs receptors, memories, signals – a whole system
of linkages that “knows” the world well enough to
switch particular behaviours on and off at the right moments.
The need became even more urgent with the evolution of multicellular
animals such as jellyfish and worms around about one billion years ago.
The development of bodies and organ system led to a complex inner world
to go with the increasingly complex outer world. A nervous system, a
network of communication, became necessary to pull the organism
together in a web of knowing and responding.
Then eventually along came higher life forms like turtles, squids and
humans. The simple nerve networks developed the denser knots that we
call ganglions, nuclei and eventually brains. And so the path between
input and output became a tangle of millions, even trillions, of
connections.
However, despite the ever growing complexity, the underlying need
remained the same. The pathways physically had to represent knowledge
of what to do in particular circumstances. And while talk of signals
and linkages make this sound a rather mechanical affair, in fact
knowledge of the world was built into brains by the impeccably organic,
impeccably holistic, process of evolutionary adaptation.
the three degrees of cognitive adaptation
To adapt to the world is to know the world in some fashion. And brains
respond over at least different three time scales.
First there are the adaptive changes that take place on a genetic time
scale. Encoded in DNA is the basic blueprint of an organism’s
brain and nervous system. This blueprint is like a frozen set of good
ideas and sensible expectations. It builds a network of connections
that is geared in a general way to the business of eating, resting,
reproducing and surviving.
Even the kinds of sensory organs and output structures with which an
organism is born are a type of genetically-encoded knowledge. A hoof,
hand or flipper, for example, is a concrete prediction about the kind
of world that an organism is going to have to survive in. The same is
true of a nose tuned to certain scents or an ear tuned to certain
frequencies.
So the genes learn to know the world in a general way. The learning is
spread over a history of experiences of whole species and even phyla of
related species. It is not a cognitive response by an individual
starfish or kangaroo but generations of starfish and kangaroos.
A second quicker and more individual cycle of adaptation then takes
place once an individual being is born and starts to develop a
functioning brain. This is developmental learning. The generalised
genetic legacy becomes fine-tuned by a personal history of experiences.
An individual’s response pathways come to reflect a private
story of the threats and opportunities that it has learnt to deal with.
Then finally, there is the adapting that the brain does in the state of
its circuitry during the course of a single moment. Every passing
instant presents a novel set of challenges and the nervous system must
mount an equally precise mental response. The general understandings
and general reactions built in by the genes and a lifetime of
experiences must be tightened to form the particular pattern of linkage
that best handles the current moment.
It is as if the brain is zeroing in on the meaning of each moment,
following an ever narrowing cone of adaptive activity. A genetic legacy
creates the general animal. A developmental history forms a specific
animal with specific memories and habits. Then in a final flurry of
adjustments, the animal’s neural pathways take on a shape
that fits each passing moment with great precision. The brain shifts
its patterns in way that represent the sensations and actions of the
moment.
This three step tapering response can be seen even in the humble E.
coli bacteria wandering our guts. Millions of years of evolution have
equipped them with a basic machinery of chemo-reception and tracking
behaviour. Then during the lifetime of each individual bacterium (which
may be just a day or so), the settings of this inherited machinery must
be adapted to the particular environment it finds itself in. The type
of receptors, and their excitability, must be fine-tuned to match what
you, the host, had for your last meal.
Then from moment to moment, the bacterium’s chemo-reception
pathway is alive with knowledge of whether the concentrations of food
are growing stronger or weaker. Or whether it is time to dive for cover
as a burst of acid indigestion passes by.
Through a process of tightening adaptation across multiple time scales,
the bacterium homes in on what is going on its world. And as we shall
see, exactly the same is true of human brains.
Also it is worth pointing out here that this is an organic story. While
for the sake of introducing the essential ideas I’ve
(mechanically) broken up “cognitive processing”
into three stages, it is really a nested hierarchy of [genome
[development [“awareness]]]. We have not a linear progression
(a series of steps) but a scale progression – a local~global
dichotomy filled by a flat scalefree middle.
Genomic knowing is the largest scale, the one spread across the most
space and time as it involves whole species and genera. Or even the
whole phenomenon of life. Development is a more localised form of
knowing. And awareness the most specific response in space and time.
So what I am saying is that these very different seeming stages are in
fact all the same basic process – the process of adaptation
or “knowing” – taking place over all
possible scales. And where we have a smoothly progressive middle ground
we must then have the dichotomous extremes that form it –
which in this case are the frozen global realm that is the memory or
ideas or universals of a cognitive system, and the blur of events that
are its sensations, its impressions, its constructing particulars.
NEXT - second page of this introduction to the brain