2 November 2019 | New Scientist | 29Don’t miss
Watch
The Aeronauts, in
UK cinemas from
8 November, casts Eddie
Redmayne as Victorian
physicist James Glaisher
exploring the upper
atmosphere in a balloon
flown by fictional Amelia
Wren (Felicity Jones).Read
Nuking the Moon was
one of many military
ideas best left on the
drawing board, as Vince
Houghton reveals in
this book (Profile). As
curator and historian
at the International Spy
Museum in Washington
DC, he would know.Listen
A Central and
Controlling Incident, on
7 November, celebrates
the intellectual legacy of
Darwin’s contemporary
and fellow biologist-
explorer Alfred Russel
Wallace with a day of
lectures at The Linnean
Society of London.
TOP: AMAZON/PLANET PHOTOS; HULTON-DEUTSCH COLLECTION/CORBIS VIA GETTY IMAGESaffected by something else. But
consciousness seems to be an
exception. We feel sure it exists
but can give no evidence of it
“causing” anything, nor can
anyone else observe it.
The way out is to say that
consciousness must have an
internal cause-and-effect structure
that gives it causal power over
itself. This may sound odd, but
“causal power” can be precisely
defined mathematically and
makes sense of an old intuition
from neuroscience: that sustained
feedback in the brain, called
recurrent or re-entry processing,
is essential for consciousness.
And, as Koch explains, it fits
perfectly with his search for
consciousness in the brain.
Circuits in a zone of the posterior
cerebral cortex, a part of the brain
that research shows is essential for
consciousness, contain elements
that can interact tightly with one
another and have high causal
power. Brain areas like the
cerebellum have more neurons
than the cortex but don’t have
this structure and aren’t able to
generate consciousness.
By now, I hope you are both
intrigued and puzzled, because
then I will have conveyed how I
felt reading Koch. The theory is
profound and you need time to
think it through. But its promise
that it can examine any system to
see if it generates consciousness
leads to surprising predictions.
Can computers be conscious?
Absolutely not. Their circuitry is
of the wrong type; they have no
intrinsic causal power and form
no whole. Bad news for those
seeking digital immortality
by uploading their brains.
Are animals conscious? The
answer isn’t a straightforward yes
or no, for some animals may have
a tiny glow of experience, while
others like humans have a brighter
light. Honeybees, for example,
have brain areas that heavily
reconnect to themselves. So being
a bee may well feel like something.
Then there is the more exotic
prediction for lovers who dream of
merging their consciousnesses. If
we could completely connect one
brain to another, the theory says
merging is possible. But beware:
you wouldn’t feel like one part of a
dual consciousness but would be
lost in a single, strange, new mind.
Tononi’s idea also explains
how meditation might lead to a
profound sense of the void. You
might think quietening nervous
activity would simply lead tounconsciousness. But Tononi’s
theory shows a key difference
between the absence of presence
and the presence of absence. One
leads to unconsciousness, the
other to “pure consciousness”
without sensation or memory.
For me, the icing on the cake
is a function for consciousness.
This part of Tonini’s theory builds
on research using artificial,
non-biological creatures dubbed
“animats”. In simulations where
they learned to navigate mazes
and the most successful passed on
their characteristics to new
generations, very skilled animats
evolved. Their tiny brains were
the ones that best integrated
information. This shows that,
in essence, organisms with the
internal cause-and-effect structure
most efficiently pack into their
brains distinctions about the
world around them. The resulting
survival advantages may explain
why consciousness evolved.
Koch’s mind-stretching book
provides a rich feast, leaving me
with a desire to understand more
about this often difficult theory.
That said, there is a sense in
which the theory is also simple,
for it extends familiar physics to
the inner view. “Textbook physics
deals with the interaction of
objects with each other, dictated
by extrinsic causal powers. My and
your experiences are the way
brains with irreducible intrinsic
causal powers feel like from the
inside,” Koch writes. “Causal
powers of two different kinds
is the only sort of stuff needed
to explain everything in the
universe. These constitute
ultimate reality.” Now there’s
a grand statement. ❚Alun Anderson is an editor emeritus
of New ScientistCan those who meditate
achieve a deep conscious
state known as the void?