More 20th Century “Blank Slate” Countercurrents—Neuroscience

 I believe that the growth and dominance of the Neurosciences from about 1975 to the present is possibly the most amazing news of our time.  Certainly for the nature/nurture debate that is the elephant in the room.  Psychologists, sociologists and others in related fields have, happily or otherwise, come to see that the extremes of human behavior that we think of as mental illness (schizophrenia, bipolar manic -depression, autism, obsessive-compulsive disorder,  etc.) have roots in altered brain structure or chemistry or both.  And this is so very recent.

In 1943 it was first noted (Leo Kanner) that parents of autistic children seemed to be unusually reserved and unemotional.  Although Kanner did not mean to suggest this as a root cause, the idea swept through the psychiatric world.  Autistic children had “refrigerator mothers”.  Bruno Bettelheim, a psychiatrist who had, himself, been interred at Dachau during WWII, wrote that these children were like prisoners in a concentration camp, but worse, since they had had no previous opportunity to develop a personality.  The idea quickly broadened to include children with schizophrenia.  It wasn’t the butler in the pantry, it was mom (and on rare occasions, dad.)

In 1961 Thomas Szasz published The Myth of Mental Illness:  Foundations of a Theory of Personal Conduct.  Here he made the bold claim that no psychiatric disorder met the appropriate criteria for “illness”.  That is, no such disorder had any observable biological abnormality.  This fitted beautifully into another part of the 60s zeitgeist—the anti-psychiatry movement.  Szasz blamed the behaviors that others thought of as madness, entirely on culture, on moral strictures that were confining and inappropriate, and on the current views of the controlling power structures of the time—business, science, government.

These views continued well into the 70s, perfectly in rythym with the broader belief in the child entering the world as a blank slate for parents to write upon.  But then what?  In the early 1970s the CT (computerized tomography) scan was born.  Brain xrays had been possible for some time, but able only to distinquish bone from tissue, and greater and lesser degrees of tissue density.  They were useful in estimating and localizing very large amounts of damage, but otherwise, very limited.  The CT scan used the xray principle but passed very narrow xray beams through, using many angles and relying on computer analysis to bring this together as a picture of the whole structure of the brain.  One of the earliest findings in schizophrenia research came first from CT scans.  It was the presence of enlarged ventricles (hollow, fluid filled spaces in the head).  The importance of this finding is that abnormal enlargement of these areas means a reduction of surrounding brain tissue, suggesting that something has gone wrong.

Other and much more powerful scans were also in development at this time.  Magnetic Resonance Imaging, (MRI) which uses a different principle entirely, was in development during the seventies. The first study done in humans occurred in 1977.  Skipping over all the details, MRI relies on the use of a magnetic field to activate hydrogen ions, and uses that activity to measure the amount of fluid present in a given area.  Areas high in fluids will show up as very dark and those high in tissues and low in fluids will be very light.  This process was used at first simply to get a better image of the brain (or other tissues) than is true with the CT scan.  However, blood flows rapidly into areas of the brain that are currently active, and the oxygen that is carried with it is selectively taken in during high activity in a given area. This proved invaluable in developing functional maps of the brain showing where activity is high, low, and everywhere in between, and showing the time course of any activity at its onset, continuation and decline.   And so?  We can give a simple task to a person in the MRI chamber and see what parts of the brain get involved and at what level and for how long.  Obviously we can also give the same task to many different individuals and see how the activity compares.  And so, biological comparison of individual differences is born.

There are now a number of different techniques for such scans.  One of considerable research importance is the PET scan, or Positron Emission Tomography.  PET relies on injecting relatively harmless radioactive substances that travel to the brain either by injection into the bloodstream or by inhalation, which are then detected.  Literally hundreds of radioactively labeled compounds can be used, and the end result is that an amazing amount of information about brain activity, use of oxygen, glucose, various neurotransmitters and receptors for these, and on and on, can be obtained.  Once again, we can look at what happens during a task in a given person, and compare this with other tasks, and compare all of this with other individuals.

Finally, the lowly EEG or electroencephalogram which has been with us since the 1930s, and simply measures electrical waves generated by the brain, has also had an upgrade, with both miniaturization of recording sites (up to 125 for one small head!) and computerization of the output.  This technique can also be used to look at brain activity under different circumstances and tasks.

There are many other vital techniques for studying both the living brain and the postmortem brain. It has become possible to study after death, the genes that have been expressed in different brain regions, and very recently the National Institutes of Health reported on a study of this kind in postmortem autism cases.  It has been known for a long time that there are many, and serious abnormalities in brain structure, especially in severe autism.  Now it seems that genes that should be turned on very differently in different portions of the cortex of the brain, are in fact much the same in different regions, in autistic brains.  The effect of this would be that regions that should handle very different tasks are actually being designed to all do much the same thing.  The article states that “tissue differences—between these regions are nearly erased in autism.”  So much for refrigerator mothers.

Schizophrenia has also been examined in many studies.  In addition to the early findings that the hollow ventricles are enlarged and functional tissue is correspondingly reduced,  there are findings of specific abnormalities in both cortical structures and in subcortical structures that play many roles in memory, emotion and general brain organization.  In the hippocampus, an area involved in short term memory, certain large neurons are clearly disorganized and random in their placement, suggesting something that had to occur early in utero.  Clearly, it is no longer possible to say that mental illness is a myth.  The   elephant in the room has won all the innings.

And what does this have to do with temperament?  Next week.

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