"This suggests that really bad experiences may have lasting effects on the brain, even in healthy people," said Barbara Ganzel, the study's lead researcher and postdoctoral fellow at Cornell's College of Human Ecology.The brain is somewhat plastic. Somewhat. It varies between individuals too. We have little knowledge about the mechanisms behind such structural changes to the brain as a response to traumatic events. That such changes happen is proven, but we don't know how they happen, what the mechanism is that causes the changes.
The study -- one of the first to look at the effects of trauma on the brains of healthy adults -- is published in the April issue of Neurolmage. It follows a Cornell study by the same authors that found people living near the World Trade Center on 9/11 have brains that are more reactive to such emotional stimuli as photographs of fearful faces. Combined, the two studies provide an emerging picture of what happens in the brains of healthy people who experience a traumatic event.
The smaller volume of gray matter -- composed largely of cells and capillary blood vessels -- that Ganzel found were in areas that process emotion and may be, Ganzel suggests, the brain's normal response to trauma. The subjects in the study did not suffer from any mental or physical health disorders. Gray matter, a major component of the nervous system, is composed of the neuron cell bodies that process information in the brain.
The researchers used two types of magnetic resonance imaging to scan the brains of 18 people who were within 1.5 miles of the World Trade Center on Sept. 11 and compared them to scans of 18 people who lived at least 200 miles away at the time. One type showed the gray matter volume, and the other showed the brain's response to emotional stimuli (pictures of fearful and calm faces). Those who were close to the disaster on Sept. 11 showed more emotional reactivity in the amygdala, a brain area that detects the presence of threatening information.
Combining the brain data revealed that those who were near the World Trade Center had smaller, more reactive amygdalas, and this, in turn, was related to how anxious they were years later. Several other brain regions associated with emotion processing were also smaller in those who were close to the disaster.
The researchers also found that study subjects who had experienced other types of trauma (violent crimes, sudden death of a loved one) showed a similar reduction in gray matter and similar response to emotional faces and anxiety.
At least with fMRI now we can do studies on people who aren't actually dead.
The methods we can use to make such gross changes are crude in the extreme. Killing 3000 people in a spectacular way, torture, imprisonment, extended "aversion therapy" for months on end... all these can cause physical changes in the brain. We're still light-years away from being able to brain-sculpt people, to predictably modify a person's personality in areas such as sexual orientation or gender identity to match our notions of social desirability. In fact, some areas, again, sexual orientation and gender identity, may be so deeply embedded into the bedrock of personality that change is not possible in the majority of cases.
The methods we use in attempts to make changes usually lead to unfortunate side-effects, dysfunctionality, depression, suicide, as well as not working terribly well. People who implement such methods can also be rightfully regarded as, if not sadists, then behaving sadistically, though often out of the highest motives.
The situation isn't black-and-white though. We mold children's personalities through teaching, and no doubt cause changes in brain structures as the result of intellectual stimulation, and this is an accepted part of human behaviour. We evolved to have our brains change over time.
Should we ever have the capability to reliably modify brain structure to produce specific behaviours and thought-patterns, we would be faced with an ethical dilemma: When is it out right to do this? For example, is it ethical to change the brain of a serial killer so they no longer see other people as animals to be slaughtered at whim? I think it is - but only with the patient's full knowledge and consent. And that requires a level of adult responsibility, so no changing the brains of 3 year olds with "propensities" for sadism, or republicanism for that matter.