fMRI Study on the Common Abnormal Neural Circuitry in Schizophrenia and Epileptic Psychosis

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The abnormal voluntary eye movements are reported to be a genetic vulnerability marker for schizophrenia. We have studied brain activation patterns during performing various eye movement tasks to elucidate abnormal neural circuitry for schizophrenia using functional MRI. We have also investigated the patients with epileptic psychosis, whose symptoms are similar to those with schizophrenia, to clarify whether the same neural circuit is affected or not. This research obtained the approval from the ethical committee of Nihon University School of Medicine. Written informed consent was obtained from all the participants after the procedure of the experiments was fully explained. The subjects were 21 normal controls (11 males/ 10 females, mean age 39.2±10.2 yrs), 18 patients with schizophrenia (12/ 6, 34.8±8.5 yrs), and five patients with epileptic psychosis (5/ 0, 34.8±14.4 yrs). Using a 1.5 Tesla clinical MRI scanner, brain imaging data were acquired with gradient-recalled EPI to obtain BO … More LD contrast encompassing the entire brain (TR 4000ms, TE 62ms, pixel size 3.0×3.0 mm, number of slices 40, FOV 192 mm, matrix 64×64, flip angle 90 deg, slice thickness 3 mm). An eye tracking instrument was used for task display and eye movement monitoring. Each subject performed five series alternating between 40 sec of four eye movement task (saccade, anti-saccade, smooth pursuit eye movement, SPEM task with attention enhancement procedure) and 40 sec of baseline (fixation). Image analysis was performed using SPM99with random-effect analysis at a significant level of uncorrected p<0.001 and cluster level corrected p<0.05.Compared with normal controls, low capacity or inefficiency in frontal function during visually-guided saccade task and striate-thalamic hypo-activation during anti-saccade task was found both in schizophrenia and epileptic psychosis. Therefore, these findings may be attributable to psychotic state. On the other hand, right hemisphere hypo-activation during smooth pursuit eye movement task with attention enhanced procedure was found only in schizophrenia. The present results are in accordance with the evidence for abnormal hemispherical laterality in schizophrenia, that have been reported by recent fMRI studies using various language tasks. Less