M. Talvik. Karolinska Hospital, Stockholm, Sweden

V. Kumari. Institute of Psychiatry, London, United Kingdom

R. Schloesser. University Of Jena, Jena, Germany

P. Delamillieure. CNRS, University of Caen et Pa, Caen, France

M. Kromkamp. University Medical Center of U, Utrecht, Netherlands

Dr Talvik's (Karolinska Hospital, Stockholm, Sweden) PET examinations of drug-naive patients with schizophrenia indicate a lower dopamine D2 receptor binding in the right thalamus as compared to control subjects. This preliminary result has recently been confirmed by two other PET groups. Taken together this new in vivo data adds to results from studies using different methods that all indicate an aberrant thalamic dopamine system in schizophrenia. Dr. Kumari's (Institute of Psychiatry, London, UK) presentation will focus on the role of thalamus as a 'sensory filter' and on schizophrenia as a 'disorder of deficient sensory gating' as assessed with prepulse inhibition of the startle response. Prepulse inhibition provides a crossspecies neuropsychological model of sensorimotor gating, serving to prevent the interruption of ongoing perceptual and early sensory analysis. There is reliable evidence for deficient prepulse inhibition in schizophrenia patients and recent neuroimaging evidence demonstrates that thalamic abnormalities play a critical role in this aspect of schizophrenia. Dr. Schloesser (University of Jena, FR Germany) will highlight the connectivity between thalamic and cortical areas during working memory performance in schizophrenic patients and healthy subjects using functional MRI and structural equation modeling. Dr. Delamillieurc (University of Caen and Paris V, France) will focus on the results of proton magnetic resonance spectroscopy of the thalamus in schizophrenia. The purpose of these studies is to show the utility of this technique in the understanding of the pathophysiology of schizophrenia. Dr. Kromkamp's (University of Utrecht, Netherlands) studies suggest a shared vulnerability to develop psychosis in thalamic circuits in schizophrenia and bipolar disorder. Homeobox genes involved in development and differentiation of the brain could play an important role in these disorders.