Molecular and Cellular Mechanisms Controlling the Development of Telencephalic Structures
Oscar Marin, Ph.D., University Miguel Hernández

Dr. Oscar Marin described examples of three basic mechanisms that influence the development of brain reward circuitry: patterning, cell migration, and axon guidance. As illustrated by experiments involving genetic manipulation of the transcription factors implicated in their development, differential patterning of the basal telencephalon is likely to generate functional divergence between the shell and core subdivisions of the nucleus accumbens. Alternately, interneuron migration is responsible for increasing the cellular complexity of brain reward circuitry. Finally, axon guidance in the mesolimbic dopamine system is required to effectively wire the brain reward circuitry. Insights into these mechanisms should contribute to understanding normal and abnormal functioning of the brain’s reward system.

Development of Dopaminergic and Serotonergic Neurons Involved in Reward-associated Behavior in Zebrafish
Su Guo, Ph.D., University of California School of Pharmacy

Reward-associated behavior results when exposure to a substance elicits preferential behavior in favor of obtaining the drug. Dr. Su Guo discussed a series of experiments on drug preference behavior in zebrafish, as well as her team’s use of a zebrafish with mutations that influence the development of dopaminergic and serotonergic neurons in the basal forebrain. From these experiments, her team concluded that zebrafish are an attractive genetic model organism to use in studying the development of specific neuronal types, in this case dopaminergic and serotonergic neurons, as well as the developmental alteration that leads to abnormal reward-associated behavior. This could ultimately allow researchers to link research on genes to neurons, then to circuitries, and ultimately to behavior.