One of the biggest questions in human psychology and behavioral research is that of nature versus nurture. Are people born with the characteristic traits that define them as adults or is it more of the environment around them that shapes who they become? Is it as Lady Gaga put it, that she was born that way? Or is it as Weird Al puts it, that she chooses to perform that way?
There certainly are arguments for both sides and research has found evidence for both as well, going to the lengths of studying identical twins who were separated at birth. While some evidence points to astounding similarities from twins reared apart, such as jewelry wearing habits, phobias, temperament and even reading magazines from back to front, other evidence points to an equal chance of them sharing traits as being different. (For more information, check out the Minnesota Twin Family Study (http://mctfr.psych.umn.edu/).
While arguments can be made as to just how much nurture can influence one’s personality traits, it has been documented repeatedly that hard-wiring of the brain definitely has an effect. The most recent piece of evidence comes from the University of Wisconsin, where research has shown that psychopaths have fundamental differences in their neural networks, showing differences even between types of psychopaths.
For the study, Michael Koenigs went to a medium-security prison in Wisconsin and interviewed inmates in order to rank them on a proven scale for psychopathy. After the interviews, his colleagues and he were able to pick 20 inmates with high scores as well as 20 with low scores who had committed similar crimes. He then put them all through two types of brain imaging scans.
The first is called diffusion tensor imaging (DFI), in which is a form of MRI that can measure the amount and direction of water diffusion through tissues. What this means for brain studies is that the technique can map and visualize white brain matter, the fibers that connect different areas of the brain, with exquisite detail. The second scan is called a functional MRI (fMRI), which can measure the amount of blood flowing through the brain in real-time, giving scientists a view of which parts of the brain are being used at any given time and to what extent.
The results of the tests showed major differences between psychopaths and non-psychopaths. For one, psychopaths were shown to have a weaker connection between the areas of the brain that are believed to regulate emotion and social behavior. In case you’re wondering, these were the ventromedial prefrontal cortex (vmPFC), the part of the brain responsible for sentiments such as empathy and guilt, and the amygdala, which mediates fear and anxiety.
The two scans separately showed a weak connection with white matter and a reduced amount of communication.
Though this has been shown before in previous research, this study used a much larger sampling size and more stringent requirements for psychopathy. What’s more, the study also showed a brand new connection – that low anxiety psychopaths (“primary”) showed lower amounts of connectivity between the vmPFC and amygdale, whereas high anxiety psychopaths (“secondary”) showed a higher amount of connectivity.
Prior to this research, the same team of scientists had shown that the decision-making of psychopaths matched those who suffered from lesions on and damage to the vmPFC.
“The decision-making study showed indirectly what this study shows directly – that there is a specific brain abnormality associated with criminal psychopathy,” said Koenigs.
The researchers hope that this understanding may someday help to actually treat psychopathy in humans. I’m sure our prison system wouldn’t mind, seeing as how approximately a quarter of adult prison inmates fall under the psychopath category.