BRAIN ACTIVATION DURING AN AUDITORY ODDBALL TASK IN SCHIZOPHRENIA MEASURED BY SINGLE-PHOTON EMISSION TOMOGRAPHY

Background. The study examines the effect of an auditory discriminatio n task on regional brain perfusion in schizophrenic patients. Methods. Twenty patients were examined with single photon emission tomography (SPET), both resting and performing an auditory two-tone 'oddball' dis crimination task. Statistical parametric mapping (SPM'95) was used to identify local activation effects and correlations between event relat ed potential measures and regional perfusion. Results. Compared with r est, patients activated left superior temporal gyrus during the task, together with right caudate. There was a (negative) correlation betwee n P300-amplitude and perfusion during the activation procedure in both caudate nuclei and in the left lingual gyrus. No correlations were ob served with P300-latency. Compared with healthy volunteers examined in earlier studies, our patients showed no frontal activation. This migh t be due to slightly different task demands in this study, but more li kely to activation-hypofrontality in schizophrenic patients compared w ith controls. Conclusion. Auditory discrimination tasks can be used in schizophrenic patients to control their 'mental set' during brain per fusion studies with SPET. This approach can yield information about sp ecific brain mechanisms associated with such tasks, and may make compa rison with healthy volunteers easier.