1953- 1959, has been a postdoctoral fellow in biochemistry at Cambridge University, University of London, Maryland National Institute of Medicine and National Institute of Health.
1959 to 1967 director of biochemistry department, reggaki research laboratory, Addis, new york, USA 19 1 to 1970 visiting associate professor and professor of pharmacology, Einstein College of Medicine, new york, USA.
1960- 1964 worked as a resident intern in the School of Psychiatry at Harvard Medical School in Boston.
1965- 1974, Associate Professor, Department of Physiology and Psychiatry, new york University.
1968 to 1983, Professor of Pharmacology and Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA, 1974 to 1983, Director of the Center for Neurobiology and Behavioral Research, Professor of Physiology and Psychiatry.
65438-0983 has been a professor in the Department of Biochemistry and Molecular Biophysics of Columbia University and a senior researcher at Harvard Huey Medical College of Columbia University.