Several major theories of addiction revolve around the role of the neurotransmitter dopamine (DA). Three distinct theories will be chosen, and the class will continually evaluate them throughout the course, in light of whether they are supported by original research papers. Each theory will “belong” to a group of five or six students, and each student will be responsible for knowing the details of that particular theory assigned to his/her group. Each week throughout the semester, students will present original research papers in journal club format. The question we will ask is, How well does the research support each theory? We will critically evaluate the theories in light of whether they are supported or refuted. Objectives include: differentiate the theories in terms of where they overlap and where they differ; identify strengths and weaknesses of each theory; determine if one theory emerges as superior; identify key research questions that could resolve discrepancies. It will not be the student’s job to defend a theory, but rather to know it well and remember its details throughout the course in order to make these weekly evaluations. Each student will be our resident authority to whom we’ll turn for objective evaluations of the theory, pro or con. Evaluations of theories will depend on our evaluations of weekly research papers. Poorly conducted studies may or may not have much bearing on the theories. Each student will keep weekly notes regarding how well the theory for which that student is responsible accommodates results of research. S/he will use these notes to write a final paper (one paper per student) evaluating the theory.
We’ll work similar to a journal club, with one or two students presenting a research paper each class meeting, with everyone reading the paper before class and critiquing the paper in class. Presenting a paper will require work before class, e.g., to read the paper carefully and discuss it with colleagues, or come to the professor to discuss it.
MARK WEST received a B.S. in Biological Sciences from the University of California, Irvine, and PhD in Physiology from Wake Forest University School of Medicine. Dr. West records ultrasonic vocalizations and single neuron activity in the mesolimbic dopamine system of rats and mice during reward-relevant behaviors. He benefited from the exciting neuroscience research atmosphere in the Department of Psychobiology at UCI in the 1970s. The focus was to study hippocampal physiology during learning. Inspired by a talk by Walle Nauta in 1978 describing the newly recognized nucleus accumbens (NAc) as a crossroads between limbic and motor systems, he transitioned to study the NAc in relation to dopamine and reward. His laboratory was the first to combine intravenous drug self-administration with electrophysiological recordings and with ultrasonic vocalization recordings (USVs). Current interests include studying the relations among NAc firing, reward seeking, and USVs in rat models of opiate or cocaine addiction, and of binge eating. He and his students recently demonstrated that cocaine self-administration involves both positive and negative affective states. Rats exhibit a transient spike in 50 kHz USVs, indicating a positive affective state, during drug “load-up” at the start of a binge. Thus, initial relapse infusions appear to involve positive reinforcement. Surprisingly, the remainder of the 6-hour binge contained no further 50 kHz “good” calls. To the contrary, 22 kHz USVs indicating negative affect occurred each time the rat’s cocaine level began to fall; 22 kHz calls temporarily ceased with each additional self-infusion. That is, after the initial “rush”, the binge was dominated by negative reinforcement, rather than positive reinforcement. The negative affect during each episode of declining drug level represents the beginning of withdrawal, which the animal escaped by taking another infusion. Our findings indicate that relapse involves the lure of the rush, followed by effectively being trapped in a binge, requiring booster doses whenever drug level falls, to escape/prevent experiencing withdrawal. These insights may reveal targets for therapy among the corresponding NAc firing patterns we record.