This is an R21 exploratory proposal. As the principal active constituents of marijuana, cannabinoids are the most widely abused class of illicit drug in the United States. A sharp increase in marijuana abuse by high school students over the last decade has been attributed to decreased perception of associated hazards. While cannabinoids lack lethality even at very high dosages, a property correlated with low CB 1 cannabinoid receptor expression in brainstem regions that control cardiorespiratory function, the potential of early cannabinoid exposure to alter brain development has not been extensively studied. In humans, early cannabis use is implicated in persistent impairment of the ability to focus attention. Accumulating evidence suggests that endogenous cannabinoid signaling plays an important role in brain development, raising the possibility that juvenile exposure may have permanent disorganizing effects. Better appreciation of the consequences of juvenile cannabinoid exposure is dependent upon identification of animal models that will allow effects to be measured over distinct developmental stages. Because zebra finches learn vocal behavior over sensitive stages of juvenile development, similar to the way in which human language is acquired, and because song behavior and its development are controlled by discrete, interconnected brain regions, we have developed this animal as a model to study cannabinoid pharmacology. We propose here to use the zebra finch model to investigate the effects of cannabinoid exposure during juvenile development at behavioral, anatomical and neurochemical levels. The results of this exploratory project will allow assessment of the suitability of the zebra finch for investigating pharmacological effects over juvenile development. Results will also expand knowledge of potential specific effects of cannabinoid exposure on development of a learned behavior.