ABSTRACTS fMRI of Schizophrenics During Verbal Recall: Sex Differences A.A. Baird, J.W. Lin, S.A. Gruber, C.D. English, P.F. Renshaw, and D.A. Yurgelun-Todd Brain Imaging Center, McLean Hospital, Belmont; Harvard Medical School, Boston, USA INTRODUCTION: Abnormal language functions, including difficulty with word association tasks, and verbal fluency, have been repeatedly demonstrated in schizophrenic patients. In a previous investigation (1) differences in activation of the superior temporal gyms were detected between normal controls and schizophrenic patients with functional MRI during word production tasks. Recent hypotheses regarding the neurobiological correlates of schizophrenia have suggested that schizophrenic males may be characterized by extreme forms of sexual dimorphism (2). In this study, we have applied fMRI during verbal recall in order to examine temporal lobe activation in schizophrenic patients and normal controls during a subspan word task. METHODS: We studied 24 right-handed subjects; six non-psychiatric control females, six non-psychiatric control males, six DSM-4 schizophrenic females, and six DSM-4 schizophrenic males. The mean ages of each group were not significantly different, Subjects were given nine separate lists of five words each at two second intervals. At the end of each list, the subjects were cued to repeat the words. To visualize signal changes, we used a task-activation paradigm which alternated between resting, listening to word lists, and immediate word recall. Details of image methodology have been published previously (3). Cortical activation was measured in a neuroanatomically defined region of interest, the left superior temporal gyms (Brodmann's area 22). Selection was based on both conventional MR and fMRI images. Activation levels were compared with baseline states. 1.1. 1.0~. _~ 1.06. -~ l.o, I .oJ. 1 ,~ 0,91 2~ 0.96 0.94 0,91 09 Time vs. Signal Intensity During Subspan Task in the Temporal Region Time {~aa~) Figure 1. 9 Controls-Females j. Controls-Males 9 Schizophrenlcs.FemM 9 $cMzophrenlcs-MMes RESULTS AND DISCUSSION: Changes in activation relative to the baseline activation were observed during the task conditions in both normal controls and schizophrenic subjects. Signal-time plots were created for subjects split by both diagnosis and sex (Fig. 1). In the temporal region, normal controls demonstrated higher activation than schizophrenic subjects during task intervals. While the difference in signal between diagnostic groups during the task was significant (p<0.05), a more dramatic divergence appeared when the groups were split by sex. Schizophrenic males demonstrated a highly significant (p< 0.01) decrease in signal intensity in the temporal region during the subspan task. The reduction in temporal lobe activation in male schizophrenics is consistent with MRI studies which report left temporal lobe abnormalities in these patients. Furthermore, these findings suggests robust sexual differentiation in activation which may provide us with important information about the neurodevelopmental nature of this disorder (4). REFERENCES 1. Yurgelun-Todd, DA, et al., Am. J. of Psych., tn Press 2. Lewinc, RR et al., Schizophrenia Res. 16:2; 195-203, 1990 3. Yurgelun-Todd, DA, et al., SMR abstracts #686, 1994 4. Lewis, S, Brit J of Psych, 161; 445-450, 1992 $474