An FMRI investigation of frontal lobe functioning in psychopathy and schizophrenia during a go/no go task

The prefrontal cortex and its connections with other regions of the brain allow for behaviors and emotions that differentiate human beings from other animals. When a deficit in this brain region arises, many disturbing results can occur. One of these deficits is difficulty in controlling inappropriate behavioral responses. This disinhibition is observed in many psychiatric disorders, including psychopathy and schizophrenia. In this study, functional magnetic resonance imaging (fMRI) and a Go/No Go paradigm were used to investigate neurophysiological processes associated with response inhibition in psychopathic and nonpsychopathic inmates, stable, medicated schizophrenic patients and healthy control participants. The results indicated that the dorsolateral prefrontal cortex is involved in response inhibition in healthy control participants. There was a significant difference between control participants and psychopathic inmates in this area of the brain. Specifically, there was a negative relationship between the measure of psychopathy (Hare Psychopathy Checklist-Revised) and activity in the dorsolateral prefrontal cortex. Schizophrenic patients showed a similar level of activation to control participants in dorsolateral prefrontal cortex. However, there was also an increase in activation in the inferior temporal cortex in schizophrenic patients where a reduction in activity occurred in control participants. The results indicate that the cortical activation normally associated with response inhibition is different in both psychopathy and schizophrenia. However, the way in which the two disorders differ from control participants is significantly different. Psychopaths have attenuated left dorsolateral prefrontal cortex activity compared to control participants suggesting that the disinhibition observed in psychopathy might be related to a deficit in processing information in this brain region. The schizophrenic patients' increased lateral temporal lobe activity provides further evidence for the hypothesis that there is anomalous coordination of activity of frontal-temporal brain regions in schizophrenia.Medicine, Faculty ofGraduat