Understanding and Preventing Violence, Volume 2: Biobehavioral Influences (1994)
Chapter: NEUROANATOMIC APPROACH
individuals with a high rate of violent behavior promises to enhance the currently available diagnostic and therapeutic tools for the management of violence.
BRAIN MECHANISMS AND VIOLENT BEHAVIOR
NEUROANATOMIC APPROACH
Physiologic research on aggression in animals has discovered that different neural circuits appear to underlie ''predatory attack" behavior as opposed to "affective defense" in animals (Siegel and Edinger, 1981, 1983; Siegel and Brutus, 1990). Sites in which electrical stimulation elicits predatory attack behavior in the cat include midbrain periaqueductal gray matter, the locus ceruleus, substantia innominata, and central nucleus of the amygdala. Brain sites that mediate affective defense reactions in the cat include the medial hypothalamus and the dorsal aspect of periaqueductal gray matter. In general, limbic structures such as the amygdala, hypothalamus, midbrain periaqueductal gray, and septal area, as well as cortical areas such as the prefrontal cortex and the anterior cingulate gyrus, contain networks of excitatory and inhibitory processes of different kinds of aggressive and defensive behavior.
Aggression in animals largely reflects an adaptive response when viewed within an evolutionary framework. Whether or not violent offending in humans constitutes an instrumental act that can be viewed as adaptive is open to question. Nevertheless, the distinction between quiet, predatory, planned attack, on the one hand, and affective, explosive aggression occurring in the context of high autonomic arousal may be of heuristic value for understanding human violence. Possibly, cat (or rat) models could serve as effective screening methods to identify new drugs—some for control of "cold calculated" aggression, others for control of "explosive" aggression. Neuroanatomic and neuropsychologic studies are needed, however, to determine whether disruption of different brain mechanisms is indeed implicated in these two forms of aggression in humans.
Data on the neuroanatomy of violence in humans stem largely from clinical studies of the effects of epileptic activity and other forms of brain damage on behavior, as well as from reports of the effects of brain resections on control of violent behavior (i.e., psychosurgery). Psychosurgical studies in Japan, India, and the United States have aimed at destroying portions of the limbic system, especially the amygdala and medial hypothalamus, in cases
