Forensic psychiatrists have long known that psychopaths lack elements of behavior and mental recognition, generally described as a 'lack of conscience', but they have always struggled to understand the underlying cause, who many believed must have been rooted in the way the brain of psychopaths works.
Scientists have now confirmed that suspicion by mapping the brain of individuals who exhibit psychopathic behavior. They have found that these individuals lack the neural structure necessary to be a normal human being who exhibits empathy towards suffering and pain in others.
In fact, they lack the 'wires' so to speak, the activity in the neural pathways that normal individual employ when their brain expresses empathy.
One percent of humans is believed to be developed in this way. In the prison population the percentage rises to between 20 and 30 %. And that is very important because they are the ones who have the highest degree of recidivism and commit the most violent crimes.
The study, published on the JAMA Psychiatry issue for April 24, entailed the examination of 80 prisoners, aged 15 to 50. All of the subjects studied volunteered for the tests. Their level of psychopathic behavior was measured before the brain scans were done for later comparison.
The MRI scans the subjects were then put through were done while the prisoners were watching scenes in which people were hurt intentionally. Their responses were then tallied and measured.
The individuals in the 'highly psychopathic' group showed significantly less activation of the ventromedial prefrontal cortex, lateral orbitofrontal cortex, the amygdala and periaqueductal gray parts of the brain. More activity was instead registered in the striatum and the insula pf the brain.
The high response in the insula in these individual was particularly significant in that this part of the brain is crucial to the emotion and somatic resonance. The other parts, where activity was actually less than expected in a normal individual coincided with the suspected cause of affective behavior already documented by psychiatrists. And these regions are important because they estimate consequence of behavior and play a role in moral decision making, thereby playing a role in emphatic expression and feelings when regarding the well being of other human beings.
Source: Science Daily 4.25.13
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