Science & technology | The neurology of consciousness
Crick's last stand
Francis Crick suggests where to find the seat of consciousness
Jul 28th 2005 |
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.
This article appeared in the Science & technology section of the print edition under the headline "Crick's last stand"
Science & technology July 30th 2005
No carnival
Roll out, roll out
Down with trees
From the July 30th 2005 edition