A
Neuroscientist’s Radical Theory of How Networks Become Conscious
BY
BRANDON KEIM11.14.13 6:30 AM
A
map of neural circuits in the human brain.
Image:
Human Connectome Project
It’s
a question that’s perplexed philosophers for centuries and scientists for
decades: Where does consciousness come from? We know it exists, at least in
ourselves. But how it arises from chemistry and electricity in our brains is an
unsolved mystery.
Neuroscientist
Christof Koch, chief scientific officer at the Allen Institute
for Brain Science, thinks he might know the answer. According to Koch,
consciousness arises within any sufficiently complex, information-processing
system. All animals, from humans on down to earthworms, are conscious; even the
internet could be. That’s just the way the universe works.
“The
electric charge of an electron doesn’t arise out of more elemental properties.
It simply has a charge,” says Koch. “Likewise, I argue that we live in a
universe of space, time, mass, energy, and consciousness arising out of complex
systems.”
What
Koch proposes is a scientifically refined version of an ancient philosophical
doctrine calledpanpsychism —
and, coming from someone else, it might sound more like spirituality than
science. But Koch has devoted the last three decades to studying the
neurological basis of consciousness. His work at the Allen Institute now puts
him at the forefront of the BRAIN
Initiative, the massive new effort to understand how brains work, which
will begin next year.
Koch’s
insights have been detailed in dozens of scientific articles and a series of
books, including last year’s Consciousness:
Confessions of a Romantic Reductionist. WIRED talked to Koch about his
understanding of this age-old question.
WIRED: How did
you come to believe in panpsychism?
Christof
Koch: I
grew up Roman Catholic, and also grew up with a dog. And what bothered me was
the idea that, while humans had souls and could go to heaven, dogs was not supposed
to have souls. Intuitively I felt that either humans or animals alike had
souls, or none did. Then I encountered Buddhism, with its emphasis on the
universal nature of the conscious mind. You find this idea in philosophy, too,
espoused by Plato and Spinoza and Schopenhauer, that psyche — consciousness
— is everywhere. I find that to be the most satisfying explanation for the
universe, for three reasons: biological, metaphysical and computational.
'What
is the simplest explanation? That consciousness extends to all these
creatures....'
WIRED: What do
you mean?
Koch: My
consciousness is an undeniable fact. One can only infer facts about the
universe, such as physics, indirectly, but the one thing I’m utterly certain of
is that I’m conscious. I might be confused about the state of my consciousness,
but I’m not confused about having it. Then, looking at the biology, all animals
have complex physiology, not just humans. And at the level of a grain of brain
matter, there’s nothing exceptional about human brains.
Only
experts can tell, under a microscope, whether a chunk of brain matter is mouse
or monkey or human — and animals have very complicated behaviors. Even
honeybees recognize individual faces, communicate the quality and location of
food sources via waggle dances, and navigate complex mazes with the aid of cues
stored in their short-term memory. If you blow a scent into their hive, they
return to where they’ve previously encountered the odor. That’s associative
memory. What is the simplest explanation for it? That consciousness extends to
all these creatures, that it’s an imminent property of highly organized pieces
of matter, such as brains.
WIRED: That’s
pretty fuzzy. How does consciousness arise? How can you quantify it?
Koch: There’s a
theory, called Integrated
Information Theory, developed by Giulio Tononi at the University of
Wisconsin, that assigns to any one brain, or any complex system, a number —
denoted by the Greek symbol of Φ — that tells you how integrated a system is,
how much more the system is than the union of its parts. Φ gives you an
information-theoretical measure of consciousness. Any system with
integrated information different from zero has consciousness. Any integration feels
like something
It's
not that any physical system has consciousness. A black hole, a heap of sand, a
bunch of isolated neurons in a dish, they're not integrated. They have no
consciousness. But complex systems do. And how much consciousness they have
depends on how many connections they have and how they’re wired up.
WIRED: Ecosystems
are interconnected. Can a forest be conscious?
Koch: In the
case of the brain, it’s the whole system that’s conscious, not the individual
nerve cells. For any one ecosystem, it’s a question of how richly the
individual components, such as the trees in a forest, are integrated within
themselves as compared to causal interactions between trees.
The
philosopher John Searle, in his review
of Consciousness, asked, “Why isn’t America conscious?” After
all, there are 300 million Americans, interacting in very complicated ways. Why
doesn’t consciousness extend to all of America? It’s because integrated
information theory postulates that consciousness is a local maximum. You and
me, for example: We’re interacting right now, but vastly less than the cells in
my brain interact with each other. While you and I are conscious as
individuals, there’s no conscious Übermind that unites us in a single entity.
You and I are not collectively conscious. It’s the same thing with ecosystems.
In each case, it’s a question of the degree and extent of causal interactions
among all components making up the system.
WIRED: The
internet is integrated. Could it be conscious?
Koch: It’s
difficult to say right now. But consider this. The internet contains about 10
billion computers, with each computer itself having a couple of billion
transistors in its CPU. So the internet has at least 10^19 transistors,
compared to the roughly 1000 trillion (or quadrillion) synapses in the human
brain. That’s about 10,000 times more transistors than synapses. But is the
internet more complex than the human brain? It depends on the degree of
integration of the internet.
For
instance, our brains are connected all the time. On the internet, computers are
packet-switching. They’re not connected permanently, but rapidly switch from
one to another. But according to my version of panpsychism, it feels like
something to be the internet — and if the internet were down, it wouldn’t feel
like anything anymore. And that is, in principle, not different from the way I
feel when I’m in a deep, dreamless sleep.
