Faculty Bibliography

Developments in brain imaging and genetics are revolutionizing our understanding of behavior, particularly the role of neurobiology in aggression and violence. In the emergency room (ER), these developments will have special application for the evaluation of patients who are assaultive and potentially homicidal. Though useful, traditional psychiatric diagnosis with its focus on categoric conditions such as personality disorders, schizophrenia, and delusional states does not tell the whole story. Brain images have shown the role of structural and functional disturbances, particularly of the prefrontal cortex and limbic system in the emergence of violent behavior. Similarly, discoveries such as the presence of an aberrant gene for producing monoamine oxidase A, which interacts with the environment to prompt antisocial behavior in boys, are making significant contributions to our understanding of how genetic abnormalities affect human behavior, particularly aggression and violence. These developments will inevitably influence not only how aggression is diagnosed in the ER, but also the disposition of afflicted individuals.

Advances in neuroscience over the past 40 or more years are causing a re-visiting of an old debate: Does man possess free will over his actions, or do forces out of his control determine his behavior? Philosophers and biologists since the beginning of recorded history have taken positions on each side of the debate. Recent discoveries of brain activation prior to conscious awareness and genetic conditions that induce impulsive violent behavior are fortifying the perspective that biological determinism is basic to the human condition. But some contemporary thinkers are conflicted in this viewpoint since "free will" is a necessary element for self-determination and for attributing personal responsibility for one's actions. Hence, modifications of strict determinism have emerged which try to incorporate the features of determinism enforced by neuroscience findings with some element of "free will", making the two seemingly opposed positions compatible. How successful this will be to rescue "free will" in the long term depends on future discoveries in neuroscience and genetics.

Despite the widespread abuse of marijuana, knowledge about its effects in the human brain is limited. Brain glucose metabolism with and without delta 9 tetrahydrocannabinol (THC) (main psychoactive component of marijuana) was evaluated in eight normal subjects and eight chronic marijuana abusers with positron emission tomography. At baseline, marijuana abusers showed lower relative cerebellar metabolism than normal subjects. THC increased relative cerebellar metabolism in all subjects, but only abusers showed increases in orbitofrontal cortex, prefrontal cortex, and basal ganglia. Cerebellar metabolism during THC intoxication was significantly correlated with the subjective sense of intoxication. The decreased cerebellar metabolism in marijuana abusers at baseline could account for the motor deficits previously reported in these subjects. The activation of orbitofrontal cortex and basal ganglia by THC in the abusers but not in the normal subjects could underlie one of the mechanisms leading to the drive and the compulsion to self-administer the drug observed in addicted individuals

Positron emission tomography with 18F-deoxyglucose was used to evaluate regional brain glucose metabolism in eight normal subjects and eight psychiatric patients with a history of repetitive violent behavior. Seven of the patients showed widespread areas of low brain metabolism. Although the location of the abnormal regions varied among patients, they showed significantly lower relative metabolic values in medial temporal and prefrontal cortices than did normal comparison subjects. These regions have been implicated as substrates for aggression and impulsivity, and their dysfunction may have contributed to the patients' violent behavior