Scans offer glimpse into normal, psychopathic brains

Using a brain scanning technique called functional magnetic resonance imaging (fMRI), researchers are learning more about what happens inside both normal and abnormal brains.

In one recent study, Kent Kiehl, Robert Hare et al. performed fMRI scans on 8 psychopathic criminals, 8 non-psychopathic criminals, and eight non-criminal controls. Psychopathic criminals are characterized by extreme callousness and narcissism, lack of remorse for their crimes, superficial charm, shallowness, and manipulative behavior. The researchers note that "compared with other inmates, psychopathic offenders commit a disproportionate amount of repetitive, often violent, criminal acts," and make up approximately one percent of the population but up to 25 percent of incarcerated offenders.

The researchers discovered that compared to controls or to criminals who were not psychopaths, psychopathic criminals showed much less emotion-related activity in several areas of the limbic system in response to negative words. These brain areas are associated with attention, emotion, and memory. In addition, the psychopaths exhibited overactivation in the bilateral fronto-temporal cortex-a region associated with semantic and decision-making processes-in response to the same stimuli.

Kiehl et al. say their findings are consistent with the hypothesis that criminal psychopaths process emotional input differently than non-psychopaths. "Presumably," they say, "the absence of appropriate limbic input regarding the affective characteristics of stimuli forces psychopathic individuals to use alternative cognitive operations and/or strategies to process affective material." They note that the deficits they detected occurred in the absence of any obvious structural abnormalities, but say that more sophisticated analyses may reveal subtle pathology.

In related research on normal subjects, Mario Beauregard and colleagues used fMRI to trace the neural processes underlying emotional self-regulation. In the study, ten male adults viewed erotic film excerpts, and were asked either to respond normally or to suppress their emotional responses.

The researchers report that viewing the films activated limbic and para-limbic structures in the brain, while inhibition of the sexual arousal generated by viewing the films was associated with activation of prefrontal regions, but not the limbic system. They note that the limbic/prefrontal system "may constitute a fundamental psychobiological mechanism through which human beings can consciously and willfully self-regulate their emotional responses," adding that "at both an individual and a collective level, a defect of this neural circuitry [or similar circuitry modulating negative emotional responses associated with limbic system activation]... may have disastrous psychological and social consequences."

"Limbic abnormalities in affective processing by criminal psychopaths as revealed by functional magnetic resonance imaging," Kent A. Kiehl, Andra M. Smith, Robert D. Hare, Adrianna Mendrek, Bruce B. Forster, Johann Brink, and Peter F. Liddle, Biological Psychiatry, Vol. 50, No. 9, November 2001, 677-84. Address: Kent Kiehl, Institute of Living, Department of Psychiatry, 400 Washington Street, Hartford, CT 06106.

"Neural correlates of conscious self-regulation of emotion," Mario Beauregard, Johanne Lévesque, and Pierre Bourgouin, Journal of Neuroscience, Vol 21, 2001, 1-6. Address: Mario Beauregard, Centre de Recherche, Institut Universitaire de Gériatrie Montréal, 4565 Queen Mary Road, Montreal, Quebec, Canada H3W 1W5, beauregm@magellan.umontreal.ca.

Related Article: [2006, Vol. 12]