Henry Szechtman Profile Chronic exposure to psychostimulant drugs has two behavioral effects that are of particular interest. The first one is a progressive increase in the drug response with chronic treatment, a phenomenon termed behavioral sensitization. The phenomenon is puzzling from a mechanistic point of view because it is not known why chronic drug exposure would result in sensitization, rather than in the expected tolerance. Sensitization is also puzzling from a functional perspective because it may be linked to the emergence of psychosis, mania, post-traumatic stress disorder, panic disorder, and addiction. Behavioral analysis in my lab has characterized sensitization induced by the dopamine agonist quinpirole as a process of build-up and strengthening of performance, thus casting sensitization as a normal biological process of enhancing motor capacity. We are now investigating the hypothesis that increased motor vigour under the drug reflects enhanced activity of dopaminergic neurons controlling energy expenditure. The second interesting effect of chronic exposure to psychostimulant drugs is the resultant transformation in the organization of activity: under quinpirole, for instance, behavior is strikingly organized, despite a marked increase in hyperactivity. In a large open field, sensitized rats move repeatedly along paths that are rigid and restricted to only a portion of the environment. As they travel, they tend to stop in specific places along their route and display fixed motor acts. Their behavior appears as if it were a compulsive motor ritual. Together with Dr David Eilam of Tel-Aviv University, we are testing the hypothesis that this quinpirole-induced transformation represents an animal model of obsessive-compulsive disorder (OCD).

Henry Szechtman Professor, Psychiatry & Behavioural Neurosciences Associate Member, Psychology Associate Member, Biology Senior Research Fellow, Ontario Mental Health Foundation B.Sc., McGill University; Ph.D., University of Pittsburgh Tel: +1 (905) 525-9140 ext. 22201 Fax: +1 (905) 522-8804 email: szechtma@mcmaster.ca Office: HSC-4N82 http://www.fhs.mcmaster.ca/ psychiatryneuroscience/faculty/szechtman/   Graduate Programme in Health Sciences Online Faculty & Staff Directory In addition to research on psychostimulants and behavior, I am studying brain mechanisms of schizophrenia using Positron Emission Tomography (PET ). One current project focuses on identifying the neuronal circuits which can produce auditory hallucinations in human subjects.

• Szechtman, H. and Woody, E.Z. Obsessive-compulsive disorder as a disturbance of security motivation. Psychological Review, 2003, in press. Download preprint as a pdf file.
• Szechtman H, Eckert MJ, Tse WS, Boersma JT, Bonura CA, McClelland JZ, Culver KE, Eilam D. Compulsive checking behavior of quinpirole-sensitized rats as an animal model of Obsessive-Compulsive Disorder(OCD): form and control, BMC Neuroscience (2001) 2:4 (12 Apr 2001).
• Szechtman, H., Talangbayan, H., Canaran, G., Dai, H. and Eilam, D. Dynamics of behavioral sensitization induced by the dopamine agonist quinpirole and a proposed central energy control mechanism . Psychopharmacology (Berl), 1994, 115, 95-104.
• Szechtman, H., Sulis, W., and Eilam, D. Quinpirole induces compulsive checking behavior in rats: a potential animal model of obsessive-compulsive disorder (OCD). Behavioral Neuroscience, 1998, 112, 1475-1485.
• Culver, K.E. and Szechtman, H. Monoamine oxidase inhibitor sensitive site implicated in sensitization to quinpirole. European Journal of Pharmacology, 1997, 339, 109-111.
• Szumlinski, K.K., Allan, M., Talangbayan, H., Tracey, A. and Szechtman, H. Locomotor sensitization to quinpirole: environment-modulated increase in efficacy and context-dependent increase in potency . Psychopharmacology (Berl.) 1997, 134, 193-200.
• Einat, H., Einat, D., Allan, M., Talangbayan, H., Tsafnat, T., and Szechtman, H. Associational and nonassociational mechanisms in locomotor sensitization to the dopamine agonist quinpirole. Psychopharmacology, 1996, 127, 95-101.
• Eilam, D. and Szechtman, H. Biphasic effect of D-2 agonist quinpirole on locomotion and movements. European Journal of Pharmacology, 1989, 161, 151-157.
• Ziegler, M. and Szechtman, H. Differences in the behavioral profile of circling under amphetamine and apomorphine in rats with unilateral lesions of the substantia nigra. Behavioral Neuroscience, 1988, 102, 276-288.
• Szechtman, H., Eilam, D., Teitelbaum, P. and Golani, I. A different look at measurement and interpretation of drug-induced behavior. Psychobiology, 1988, 16, 164-173.
  Sullivan, R.M. and Szechtman, H. Asymmetrical influence of mesocortical dopamine depletion on stress ulcer development and subcortical dopamine systems in rats: implications for psychopathology. Neuroscience, 1995, 65, 757-766.
• Szechtman, H., Nahmias, C., Garnett, E.S., Firnau, G., Brown, G.M., Kaplan, R.D., and Cleghorn, J.M. Effect of neuroleptics on altered cerebral glucose metabolism in schizophrenia . Archives of General Psychiatry, 1988, 45, 523-532
• Szechtman, H., Kaplan, R.D., Nahmias, C., Firnau, G. and Garnett, E.S. Seeing auditory hallucinations. Masters in Psychiatry, (a publication of Cliggott Communications for The Upjohn Company and Solvay Pharmaceuticals), 1994.
• Szechtman, H., Woody, E., Bowers, K.S. and Nahmias, C. Where the imaginal appears real: a positron emission tomography study of auditory hallucinations. Proceedings of the National Academy of Sciences of the United States of America, 1998, 95, 1956-1960.
  

Click on the INABIS '98 icon to visit the 5th Internet World Congress for Biomedical Sciences where I served as Congress President.