Demystifying the Mind
this feature is the final installment in a
three-part series on the scientific struggle
to explain consciousness. to read the
entire series, visit sciencenews.org/mind
other researchers, inspiring a new way
to see the consciousness problem. “This
insight was very important to me,” says
Anil Seth of the Sackler Centre for Con-
sciousness Science at the University of
Sussex in Brighton, England. “I thought,
there’s something right about all this.”
So far, the new equations exist only
as prototypes, like model airplanes that
can’t fly but still help clarify how jumbo
jets stay aloft. But researchers believe
that these prototypes may one day lead
to a tool that can measure conscious-
ness, even when signs of it are ambigu-
ous. Already, researchers are testing the
math that would underpin such a tool in
human brains as people lose awareness.
Tononi’s idea, though, extends beyond
humans. By moving from nerve cells to
the math that describes them, he has
untethered the theory of consciousness
from the physical brain. Like amorphous
Silly Putty, the equations can be molded
to fit any system. With the right calculations, scientists could test whether a
tornado with its innumerable dust particles circling in unison, 2050’s iPhone
or the trillions of megabytes of information zooming around the Internet could
have some degree of consciousness.
In the same way that a thermometer
made plain the concept of temperature
(for a boiling pot of water or a person’s
body), a consciousness yardstick could
ultimately lead to a better understanding
of the substance of consciousness itself.
Because Tononi’s theory focuses on
the very essence of awareness, neuroscientist Christof Koch believes that it is
“the only true theory of consciousness.”
Scientists have amassed an impressive
list of the brain changes that occur when
consciousness comes or goes, Koch says,
but such a list can’t provide a full explanation of the mysterious process from
which conscious experience emerges.
“Why is it in this area and not that area?
What is it about this area, or this brain,
or these neurons that give rise to conscious sensation?” says Koch, of Caltech
and the Allen Institute for Brain Science
in Seattle. What’s needed is an answer
to the all-important “why?” “The only
theory that does that in a fundamental
way is Tononi’s.”
All about integration
Tononi’s theory defines consciousness as
the capacity of a system — any system — to
connect and use information. The idea
rests on two simple observations: First,
a single moment of human experience is
one of the most information-heavy things
in the universe, an observation so simple
that it’s often overlooked, Tononi says.
People usually talk about information as something gained: Infomercials
entreat viewers to call for more information, criminal investors acquire insider
information and spies gather clandestine information. But technically,
information has more to do with what’s
lost. In its professional job description,
it is a measure of how much uncertainty
has been whittled away.
Before it’s locked in, any single
moment of existence could play out in a
nearly limitless number of ways. But the
instant an experience gels, the options
vanish. Simply existing — getting out of
bed on a Sunday morning, watching a
touchdown during an afternoon football
game or just staring off into space — rules
out all alternatives.
Even the brain of a person in a chair in
absolute darkness is an information gold
mine. “When you see pure darkness, it’s
a particular scene that differs from tril-
lions of other scenes in a particular way,”
Tononi says. “And therefore it becomes
super meaningful.”
For tribes of specialized nerve cells in
the human brain, no subtle distinction is
too small: Groups of neurons form cot-
tage industries that can tell cobalt from
royal blue, remember your high school
lab partner’s name and assess whether
the Giants receiver stepped out-of-
bounds as he made his catch.
But it’s not enough for a system to
have vast stores of information stashed
around the brain in isolation. Those
diverse specialists must all talk to
one another, the second principle of
Tononi’s theory. Integration is what
makes every conscious experience a uni-
fied whole. “Every experience is what it
is. You cannot break it into independent
pieces,” Tononi says. “You cannot expe-
rience the right side independent of the
left side, the color without the shape.”
Together, these two concepts —infor-
mation and integration — describe what
consciousness actually feels like, Seth
says. “The relevant brain mechanisms are
somehow bound together, but somehow
doing their own thing, so you get the rich-
ness of the experience,” he says. A bee-
hive’s forager bees, nurse bees and queen
all have specialized abilities and knowl-
edge but are required to work together
to make the hive buzz along. A similar
thing may be going on in consciousness.
Two rules a newly proposed theory defines
consciousness as a system’s information content and capacity to connect that information.
though recognizable
as a face, this image
is so information-poor that it could be
your mother’s, neighbor’s or coworker’s.
Low information
here, the pieces
— eyes, ears,
lips — appear in rich
detail. but they don’t
connect to generate
something more.
Low integration
High information
and integration
a fully formed face
rendered in abun-
dant detail with its
pieces connected
represents high
information and
integration.
