ABSTRACT
Our fascination with the brain’s involvement in behavior is seemingly as old as humanity. Multiple trepanations, in which holes are gouged or pounded or punctured into the cranium, had one likely intent of altering behavior. Similarly, the various fluids produced by the body were seen by the ancient Greeks as the basis for an early theory of personality. For example, an excess of yellow bile was viewed as producing a pattern of behaviors that today might draw the label of conduct disorder (CD) or oppositional defiant disorder (ODD). Currently, we are in a period of resurgence of interest in the brain and behavior. This renewed interest is driven in part by the poor predictability of strictly sociological/psychological theories but mostly because of an explosion in new technologies for neuroscientific inquiry. This focus is further abetted by the burgeoning enthusiasm for genetic explanations also borne of paradigm shifting new technologies. In regard to the flood of genetic findings, the quintessential question remains: What are the affected mechanisms or structures that effect behavior? Although the rapid growth of this knowledge gives the impression of drinking from a fire hose and rampant enthusiasm abounds, a quote by Newton (Oxford Dictionary of Quotations, 1980) is quite germane. “We are,” Newton said, “finding pretty pebbles on the beach while the great ocean of truth lies undiscovered before us” (p. 362). What follows is an attempt to count and order some pebbles. First, however, there are three caveats. We do not simply focus on those strategies that have investigated the psychobiology of CD and ODD. Healthy debate over the definitions of these concepts persists. Though per-
Jean-Marc Assaad McGill University, Quebec, Canada
haps clinically useful, the dichotomous and multisymptomatic nature of these terms is a bane to replicable scientific inquiry. Thus, what is required are more specific dependent variables. Hence, “physical aggression” is in essence added to the title of this chapter. A second caveat is that we liberally speculate regarding likely mechanisms, as meaning will ultimately be derived from whichever explanation proves to have staying power. The third and most important caveat involves the framework in which one reads and digests the following facts and speculations. The behaviors in question in this text are the result of multifactorial influences that are likely very interactive. Thus, it is imperative that one see the following as a part of a bigger picture and think in terms of contributing interacting factors at many levels of analysis.
