Criminal Psychopaths showed reduced activation in brain when processing emotional facial expressions
Dec 1, 2006 - 4:30:02 PM
A new study has found that there are biological brain differences among criminal psychopaths, compared with normal people, when they process facial emotion.
The criminal psychopaths showed reduced activation in brain when processing emotional facial expressions. Also, viewing fearful faces is associated with relative deactivation of face processing areas in psychopaths.
It has been suggested that people with psychopathic disorders lack empathy because they have defects in processing facial and vocal expressions of distress, such as fear and sadness, in others.
The aims of this study, published in the December issue of the British Journal of Psychiatry, were to investigate brain function when people with psychopathy and a control group process facial emotion.
The researchers used a brain imaging technique known as event-related functional magnetic resonance imaging (fMRI) to examine neural responses when people with psychopathy and a control group viewed expressions of distress (fearful faces), of positive emotion (happy faces), and neutral faces.
They compared 6 psychopaths (people scoring over 25 on a psychopathy checklist) and 9 non-psychopathic healthy volunteers. All the people with psychopathy were repeat offenders with multiple offence types, including attempted murder, manslaughter, multiple rape with strangulation and grievous bodily harm.
Participants were studied, using a brain scanner, when they were presented with facial expressions of happiness and fear, and also with neutral expressions. They were asked to decide the gender of each face, so allowing ‘implicit’ or automatic brain responses to facial expressions to be measured.
It was found that the psychopathy group showed significantly less activation than the control group in the fusiform and extrastriate areas of the brain when processing both facial expressions. These brain regions are known, in the healthy population, to be involved in the visual analysis of faces, and are more active when processing emotional, compared to neutral, facial expressions.
However, emotion type affected response pattern.
Both groups increased fusiform and extrastriate cortex activation when processing happy faces compared with neutral faces, but this increase was significantly smaller in the psychopathy group.
By contrast, when processing fearful faces compared with neutral faces, the control group showed increased activation, but the psychopathy group decreased activation, in the fusiform area.
In summary, people with psychopathy showed reduced activation in brain regions which process facial expressions in response to both fearful and happy faces, compared with controls. Also viewing fearful faces is associated with relative deactivation of face processing areas in psychopaths.
These results suggest that the neural pathways for processing facial expressions of happiness are functionally intact in people with psychopathic disorder, although less responsive than those of controls. In contrast, fear is processed in a very different way.
The researchers comment that failure to recognise and emotionally respond to facial and other signals of distress may underlie failure to inhibit behaviour that causes distress in others during social interactions – or, more generally, may underlie the lack of emotional empathy observed among people with psychopathy.
Reduced emotional responses to facial expressions of distress may lead to failure to learn links between behaviour causing distress to others and ‘aversive arousal’, so contributing to impaired moral socialisation in people with psychopathy.
Further, impairment of aversive conditioning may make people with psychopathy less anxious when anticipating the consequences of their actions, and less responsive to punishment for them.
Further studies are needed to clarify how brain abnormalities in people with psychopathy arise, and how they affect social behaviour and socialisation.
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