1. Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland.
2. Department of Anatomy and Neurobiology, Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico.
3. Department of Psychological Sciences, University of Connecticut, Storrs, Connecticut.
4. Department of Pharmacology, Federal University of Santa Catarina, Florianópolis, Brazil.