Notebooks

Neuropsychology

08 Apr 2014 13:41

The attempt to understand mental functions by correlating them with the activities of particular parts of the brain. The science might be said to have really begun with Paul Broca's classic paper showing how a particular form of aphasia was caused by damage to a particular region of the brain. For many years such lesion studies formed almost the sole probe available to neuropsychologists, and the ingenuity in some lesion studies is truly astounding. I recall having read someplace, but cannot now find the citation, that one of the things which made the early studies possible was the replacement, first in the American Civil War and then in the Franco-Prussian War, of muskets by rifled bullets, which left much smaller wounds --- the result being that, if a soldier survived a head wound, he was much more likely to have a specific disorder, rather than just being generally "cracked in his intellectuals" (as Patrick O'Brian's characters would say). Be that as it may, for many years the best and most active neuropsychologists in the world were to be found in the Soviet Union, for two reasons:

  1. They had official support for being materialist and analytical, at a time when Western neuroscience was often sunk in holistic or behaviorist darkness, and leading neuropsychologists reciprocated by dressing their findings up in appropriate dialectical language (easily divided through for);
  2. The Soviets had more walking wounded from the Great Patriotic War than any other country.
The result was that the Soviet scholars had an unrivalled opportunity to correlate damage to the brain and psychological incapacities, which they seized, with results which are fascinating in themselves, and even of some use in helping those with brain damage recover some of their lost functions. (Eventually, of course, the rest of the world began to catch up, and probably the lead in neuropsychology, as with most other sciences, is now held by America, where it tends to be called things like "cognitive neuroscience." Reductionism and the study of mental function both became respectable in this country after World War II --- what with molecular biology on the one hand, and computers and cognitive science on the other --- and there were great heaping scads of money for biomedical research.)

Today, of course, we no longer have a large supply of Red Army veterans with head-wounds, and in fact lesion studies are much less necessary, because we can now look at the anatomy and even the activity of living, thinking brains. (The key invention here is nuclear magnetic resonance, a fairly arcane bit of physics which had no particular use for several decades after it was discovered, and would've been an excellent candidate for de-funding as a mere curiosity. Need I draw the moral?) This is exceedingly neat, and, gratifyingly, the results confirm those of lesion studies exactly. (That is, when the lesionnaires had figured out that knocking out one region of the brain keeps you from doing something, lo and behold that region is used in that activity.)

The picture which emerges from all this is of a brain composed of immense numbers of highly specialized sub-units, connected together in various ways to perform the complex tasks we take for granted, in ways that have little to do with our introspective impressions or common-sense notions or (most) philosophical theories. Things which seem elementary and indivisible turn out to be the products of complicated arrangements of many different, widely separated, specialized bits of the brain, acting in concert but without any discernable central control. ("The closer you look at the brain, the less it seems like there's anybody home," is the way one of my neuroscience professors once put it.) This raises all sorts of fascinating questions, half-scientific and half-philosophical (like, How did all those little bits of grey matter get specialized?, and What happens when we learn to do something complicated?): but another time.


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