A USC professor used MRI brain scans, a battery of cognitive function tests, and criminal histories to compare normal people with psychopaths and also to compare psychopaths who manage to avoid getting caught with psychopaths who get arrested for committing crimes.
Adrian Raine, a professor of psychology and neuroscience in the USC College of Letters, Arts & Sciences, focused his research on two parts of the brain: the hippocampus, a portion of the temporal lobe that regulates aggression and transfers information into memory; and the corpus callosum, a bridge of nerve fibers that connects the cerebral hemispheres.
One type of psychopath is adept at avoiding getting caught committing crimes but another type is not.
To explore the physical roots to psychopathic behavior, Raine and his colleagues recruited 91 men from Los Angeles' temporary employment pool and gave them a battery of tests to assess cognitive ability, information processing skills and criminal history. They also were given MRIs, or brain scans.

In the study of the hippocampus, the research team expanded the scope of previous studies by comparing the brains of two groups for the first time: "successful" psychopaths - those who had committed crimes but had never been caught - and "unsuccessful" psychopaths - those who had been caught.

The hippocampus plays a critical role in regulating aggression and in learning which situations one should be afraid of - a process called contextual fear conditioning.

With psychopaths, contextual fear conditioning plays a part in learning the concept of what to do and what not to do, Raine said. It has been theorized that the disruption of the circuit linking the hippocampus with the prefrontal cortex could contribute to the impulsiveness, lack of control and emotional abnormalities observed in psychopaths.

"It is learning what is right and what is wrong in a certain situation," he said.
The difference between successful psychopaths (those who avoid getting arrested) and unsuccessful psychopaths is that the more successful ones have a greater ability to learn fear of getting caught and to therefore guide their own behavior to minimize the chances of getting caught.
He tested the theory that psychopaths with hippocampal impairments could become insensitive to cues that predicted punishment and capture. As a result, he said, these "impaired' psychopaths were more likely to be apprehended than psychopaths without that deficit.

Fewer than half of both the control subjects and the "successful" psychopaths had an asymmetrical hippocampus.

Ninety-four percent of the unsuccessful psychopaths had that same abnormality, with the right side of the hippocampus larger than the left.
The successful and unsuccessful psychopaths share in common a different form of faulty brain wiring that causes them to lack empathy and consideration for other people.
These findings were bolstered by the results of the second study, which focused on the corpus callosum.

The corpus callosum is a bundle of nerve fibers that connects the two hemispheres of the brain, enabling them to work together to process information and regulate autonomic function. Raine explored its role in psychopathy for the first time.

"There's faulty wiring going on in psychopaths. They're wired differently than other people," Raine said. "In a way, it's literally true in this case."

He found that the psychopaths' corpus callosums were an average of 23 percent larger and 7 percent longer than the control groups'.

"The corpus callosum is bigger, but it's also thinner. That suggests that it developed abnormally," Raine said.

The rate that the psychopaths transmitted information from one hemisphere to the other through the corpus callosum also was abnormally high, Raine said.

But that didn't mean things worked better.

With an increased corpus callosum came less remorse, fewer emotions and less social connectedness - the classic hallmarks of a psychopath, he said.

"These people don't react. They don't care," Raine said. "Why that occurs, we don't fully know, but we are beginning to get important clues from neuro-imaging research."
When it comes possible to diagnose psychopaths should they be placed under greater sustained law enforcement scrutiny? The better adapted psychopaths who feel a great deal of fear of getting caught are currently getting away with many crimes. If we can identify who they are should they be treated differently?

Also, if a psychopath can be diagnosed in advance as extremely dangerous should it be permitted to lock such a person up in an institution before they rape or kill or do other harm to people? What if a person could be identified as a psychopath at the age of 14? Should such a person be removed from normal society?

Suppose it became possible to treat the brains of psychopaths to cause them to have greater empathy, greater remorse, and less impulsiveness. Should the government have the power to compel psychopaths to accept treatment that will change the wiring of their brains?

Also, if there is a genetic basis for psychopathy and it becomes possible to test for it then should people who have the genetic variations for psychopathic brain wiring be allowed to reproduce? Should they be allowed to reproduce if only they submit to genetic engineering of their developing offspring?

I predict that most of these hypothetical questions will become real questions that will be debated in many countries around the world. I also predict that most populations will support either preemptive restraint of psychopaths or forced treatment to change the brains of psychopaths to make them less dangerous.