CORTICAL CONTROL OF SACCADE IN NORMAL AND SCHIZOPHRENIC SUBJECTS - A PET STUDY USING A TASK-EVOKED RCBF PARADIGM

In this study, positron emission tomography (PET) was used to evaluate cortical control of saccades. Regional cerebral blood flow (rCBF) pat terns demonstrated by O-15 water PET during saccadic task performance were tested in 13 normal volunteers and 20 ICD-9 schizo phrenics (10 u nmedicated and 10 medicated). The following 3 saccadic tasks, which we re controlled for sensory input and oculomotor output, were applied: ( 1) reflexive saccade=visually guided saccade, (2) volitional saccade=v isually guided saccade with distracting stimuli, and (3) memory guided saccade. Schizophrenics lacked the frontal eye field (FEF) activation during every saccadic task. The left dorsolateral prefrontal cortex ( DLPFC) was activated during volitional saccade only in normal controls . The rCBF of posterior parietal cortex increased in pararell with tha t in the DLPFC. These findings suggest functional hypofrontality in sc hizophrenia and the left DLPFC-PPC's crucial role in saccade against d istracting stimuli and its dysfunction in the disease.