It began with a casual question that neuroscientist Kent Kiehl posed to a postdoctoral fellow in his laboratory who had been conducting brain scans on New Mexico prison inmates.

“I asked, ‘Does ACC activity predict the risk of reoffending?’ ” Kiehl recalls, using the scientific shorthand for the anterior cingulate cortex, a brain structure associated with error processing.

The postdoctoral fellow, Eyal Aharoni, decided to find out. When he compared 96 inmates whose brains had been monitored while they performed a test that measures impulsiveness, he discovered a stark contrast: Those with low ACC activity were about twice as likely to commit crimes within four years of being released as those with high ACC activity.

“We cannot say with certainty that all who are in the high-risk category will reoffend -- just that most will,” Kiehl says. “It has very big implications for how we think about treatment and rehabilitation.”


The study is the latest paper from Kiehl’s lab reporting on experiments performed in a powerful functional magnetic resonance imaging scanner mounted in a semitrailer. Kiehl and his team at the nonprofit Mind Research Network have used the scanner to study the brains of nearly 3,000 convicted criminals at facilities in New Mexico and Wisconsin since 2007.

Each inmate who volunteers for testing is paid a small hourly stipend and receives a copy of the brain scan, Kiehl says. But the scan is just part of a lengthy process in which Kiehl’s assistants interview the inmates, review their prison files and assign scores on the Psychopathy Checklist-Revised, a standard test for measuring psychopathy.

The MRI trailer is parked in a secure area of the prison compound, but no guards are present during the testing, Kiehl says. “Our staff are trained in prison security protocols,” he says.

The trove of data they have gathered has revealed telltale abnormalities in the structure and functioning of psychopaths’ brains. On the whole, they have less gray matter in the paralimbic system -- believed to help regulate emotion -- which may help account for their characteristic glibness, pathological lying, lack of empathy and tendency to act impulsively.


Kiehl often briefs judges and legal groups on his findings and has consulted in more than 100 criminal cases where, for example, psychopathy might be raised as a mitigating factor to account for a defendant’s impaired self-control.

The mere suggestion that it might be possible to predict future criminal behavior may conjure up such futuristic films as “Minority Report,” but Kiehl cautions that the new study merely averages test results from a large group and cannot at this point predict whether any particular individual will reoffend.

But with further refinement, he says, brain imaging might one day be considered in civil commitment proceedings, where convicted sexual offenders can be held indefinitely if it is believed they have a propensity to reoffend.

Predictions about whether an offender poses an ongoing danger to society “already play roles in a variety of legal contexts, such as in deciding whether to sentence a criminal offender to a mental health facility, deciding whether to grant parole and the like,” says Owen D. Jones, a Vanderbilt University professor of law and biology and director of the MacArthur Foundation Law and Neuroscience Project, which helped fund Kiehl’s study.


Describing the study as interesting and well-designed, Jones says the neuroscience of criminal behavior is evolving so rapidly that courts and lawmakers can barely keep up. “Although there are efforts underway to help the legal system close that gap, the gap remains,” he says. “This poses challenges to the fair and effective administration of justice.”

After hundreds of encounters with psychopaths, Jones has come to view their distinctive lack of empathy as a missing skill, akin to a dyslexic’s inability to read.

Some experts see psychopathy as an incurable defect, but Kiehl cites neuroplasticity -- the brain’s lifelong ability to remold itself in the face of new stimuli -- as cause for optimism: New therapies might be developed to bolster the psychopathic brain’s underactive empathy circuits, he says.

Selling that idea to judges and lawmakers, however, is likely to be an uphill battle. “The problem is, people don’t think about empathy as an ability,” he says. “They take it for granted.”


Kiehl, who has received inquiries from neuroscientists throughout North America and Europe about using his mobile MRI for data collection, is hard at work adding to the existing database of New Mexico and Wisconsin inmates.

“There are also other opportunities where it could be leased commercially,” Kiehl says. “We’re going to go international.”

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