We use two models of drug abuse in monkeys: drug self-administration and drug discrimination. In drug self-administration, monkeys are surgically prepared with chronic indwelling intravenous catheters, and they are trained to make an operant response that results in the delivery of cocaine, methamphetamine, nicotine or other drugs of interest.
In drug discrimination, responding is differentially reinforced in the presence or absence of cocaine and, in other animals, nicotine, methamphetamine or the dopamine D2/D3 receptor agonist quinpirole. In both types of animal models, the effects of potential treatments (both pharmacological and behavioral) are examined.
We have extended our behavioral characterizations of drug effects to include models of cognition using CANTAB touch screens. In addition, when combined with PET imaging, the effects of cocaine on brain function can be assessed at all phases of drug abuse—from acquisition, through maintenance and into withdrawal.
Furthermore, we can examine how environmental context alters brain function and, subsequently, the reinforcing effects of cocaine. My laboratory is interested in identifying factors that predispose an individual to drug abuse. We have the only laboratory in the world studying intravenous drug self-administration in socially housed monkeys. Overall, these studies are providing evidence that combining behavioral pharmacology with brain imaging provides valuable information about the interactions among drugs, the environment and the organism. This approach should aid in the understanding of variables that mediate the high abuse liability of stimulant drugs and ultimately in identifying effective behavioral and pharmacological treatment strategies.