Tuesday, 23 January 2007
Life Begins at...

Touching—very peripherally—on the beginning-of-life issue, here are some interesting comments from neuroscientist George Buzsaki, in a ten-questions interview at the Gene Expression website.  I note, though, that Prof. Buzsaki doesn't really answer the question.

Q6.  Your discussion of the brain's first rhythm could make one feel that we are close to understanding when meaningful cognition begins. Does your knowledge of EEG patterns and their underpinnings influence your thinking about beginning-of-life, end-of-life, or even animal rights debates?

A6.  I believe that cognition begins once the 1/f features of cortical rhythms emerge because this dynamics represents global (i.e., distributed) computation and only structures with these features appear to generate conscious experience. The ontogenetic appearance of 1/f dynamics coincides with the emergence of long-range cortico-cortical projections. In the newborn human the 1/f global feature of the EEG is already present. On the other hand, in preterm babies, depending on the gestation age, long seconds of neuronal silence alternate with short, spatially localized oscillatory bursts (known as "delta brush"), like in sharks and lizards. These localized intermittent cortical patterns in the premature brain, and similar ones in the strictly locally organized adult cerebellum, cannot give rise to conscious awareness, no matter the size. From this perspective, the structure-function relations between the small world network-like features of the cerebral cortex and the resultant global rhythms appear as necessary conditions for awareness. Earlier developmental stages without these properties simply do not have the necessary ingredients of the product we call cognition.

Posted on 01/23/2007 1:57 PM by John Derbyshire
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