Brain Network of a Psychopath

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, released by the American Psychiatric Association in 2013, lists psychopathy under the heading of Antisocial Personality Disorders (ASPD), while the World Health Organization delineates a similar category it calls "dissocial personality disorder."

For us, caring is a largely emotion-driven enterprise. The brains of psychopaths have been found to have weak connections among the components of the brain’s emotional systems. These disconnects are responsible for the psychopath’s inability to feel emotions deeply. Psychopaths are also not good at detecting fear in the faces of other people. The emotion of disgust also plays an important role on our ethical sense.

One promising new line of research is based on the recent discovery of a brain network responsible for understanding the minds of others. Called the default mode network (because it also performs other tasks and is operating most of the time when we are awake), it involves a cluster of several different areas in the brain’s cortex. The first studies have been done on the function of this network in psychopaths, and as expected, there are problems there. Different studies have noted “aberrant functional connectivity” among the parts of the network, along with reduced volume in some of the network's crucial areas.The criteria for dis-social personality disorder include a “callous unconcern for the feelings of others.”

Psychopaths are notorious for their lack of fear. When normal people are put into an experimental situation where they anticipate that something painful will happen, such as a mild electric shock or a mildly aversive pressure applied to a limb, a brain network activates. Normal people will also show a clear skin conductance response produced by sweat gland activity. In psychopathic subjects, however, this brain network showed no activity, and no skin conductance responses were emitted.

The Stroop task, in which the subject must state which color words are printed in. The problem is that the words themselves are conflicting color words, such as “red” printed in blue ink, so the subjects must suppress a strong inclination to read the words. There are now several studies indicating that psychopaths actually perform better than normal people on these tasks, perhaps because they are not distracted by the discrepant color.

What do you think are there degrees of psychopathy, so that normal people may possess psychopathic traits?