The neurology of consciousness

Source: The Economist
http://www.economist.com/science/displayStory.cfm?story_id=4221513

The neurology of consciousness

Crick's last stand

Jul 28th 2005 From The Economist print edition

Francis Crick suggests where to find the seat of consciousness

IT IS traditional to begin an article about Francis Crick by quoting his
collaborator, James Watson, who wrote, “I have never seen Francis Crick in
a modest mood.” The immodesty that carried Crick to the discovery of the
structure of DNA in 1953 clearly never left him. His latest paper (and his
last, for he died in 2004) proposes to explain, of all things, the
neurological basis of human consciousness.

Mechanistic explanations of consciousness are hard to come by because
consciousness is so poorly understood. Indeed, it is one of the few
unexplained phenomena that are genuinely mysterious rather than merely
problematical. But Crick, together with his long-time collaborator Christof
Koch, of the California Institute of Technology in Pasadena, focused on a
part of the mystery that seems tractable. This is the integrated nature of
conscious sensation.

As the two researchers put it in their paper, which was published this week
in the Philosophical Transactions of the Royal Society, “When holding a
rose, you smell its fragrance and see its red petals while feeling its
textured stem with your fingers.”

The part of the brain that caught the two researchers' interest is the
claustrum, a thin sheet of grey matter that lies concealed beneath part of
the cortex (the outer covering of the brain that carries out the
computations involved in seeing, hearing and language).

The key to the researchers' claim is that most, if not all, regions of the
cortex have two-way connections to the claustrum, as do the structures
involved in emotion. It is plausible that the smell, the colour and the
texture of the rose, all processed in different parts of the cortex, could
be bound together into one cohesive, conscious experience by the claustrum.
The authors liken it to a conductor who synchronises and co-ordinates
various parts into a united whole.

Thus far, this is mere anatomical speculation fuelled by the fact that very
little is known about what the claustrum actually does. Crick hoped that
his final paper would inspire researchers to begin to develop molecular
techniques to disable the claustrum in animals to observe the aftermath.
Time will tell whether Crick's spectacular contribution to understanding
genetics will be replicated in the sphere of consciousness.

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