“Cognitive Function in an Animal Model of Drug Addiction: Instrumental Learning in Rats Behavioral Sensitized to Methamphetamine”

Anne Marie Brady, Ph.D., St. Mary’s College of Maryland, St. Mary’s City, MD 20686

Chronic psychostimulant use in humans is detrimental to neurobiological and cognitive functioning. We will use an animal model of addictive behavior, behavioral sensitization, to investigate cognitive and motivational functions after repeated exposure to methamphetamine. Methamphetamine-treated and saline-treated rats will be tested on two instrumental learning tasks for food reinforcement. Acquisition of lever-pressing is mediated by dopamine and glutamate afferents to the nucleus accumbens, and synaptic interactions between these inputs are disrupted in sensitized animals. Thus, we predict that learning will be impaired in sensitized rats. Progressive ratio performance measures motivation and reward value, and human drug users are less sensitive to non-drug reinforcement. Thus, we predict that sensitized rats will not work as hard to obtain food. These experiments will begin to characterize potential learning and motivational impairments in sensitized animals, and will provide a conceptual framework within which to investigate neurobiological adaptations that underlie drug-induced impairments in human cognition.

Anne Marie Brady, Ph.D.
Assistant Professor of Psychology
St. Mary’s College of Maryland
18952 E. Fisher Road
St. Mary’s City, MD 20686

Phone: 240-895-4258
Fax: 240-895-4436

ambrady@smcm.edu