Two nonhuman primate models of drug abuse, self-administration and discrimination, are employed in the laboratory in an effort to better understand the behavioral and neurochemical effects of abused drugs, with a focus on cocaine. In self-administration studies, rhesus or cynomolgus monkeys are surgically prepared with chronically-indwelling intravenous catheters and are trained to make an operant response that results in the delivery of cocaine. In drug discrimination studies, monkeys are reinforced for different responses in the presence vs. absence of cocaine.
The noninvasive imaging procedure of Positron Emission Tomography (PET) is used to study changes in dopamine and serotonin receptors and transporters as a consequence of cocaine exposure and abstinence. In addition, studies are underway to adapt MRI-based imaging procedures, including diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS), for use in monkeys.
in vivo microdialysis
To better understand the roles of monoamines (particularly dopamine and serotonin) in the behavioral effects of cocaine, we use microdialysis, a technique that involves sampling the extracellular fluid in discrete brain regions and determining the content of neurotransmitters and their metabolites.
Socially housed monkeys
Studies in this laboratory investigate the effects of chronic social stress and enrichment on dopamine function and on the behavioral effects of cocaine in group-housed monkeys.