Complexity of Prefrontal Cortical Dysfunction in Schizophrenia: More Than Up or Down

Numerous neuroimaging studies have examined the function of the dorsolateral prefrontal cortex in schizophrenia; although abnormalities usually are identified, it is unclear why some studies find too little activation and others too much. The authors' goal was to explore this phenomenon. METHOD: They used the N-back working memory task and functional magnetic resonance imaging at 3 T to examine a group of 14 patients with schizophrenia and a matched comparison group of 14 healthy subjects.

Patients' performance was significantly worse on the two-back working memory task than that of healthy subjects. However, there were areas within the dorsolateral prefrontal cortex of the patients that were more active and areas that were less active than those of the healthy subjects. When the groups were subdivided on the basis of performance on the working memory task into healthy subjects and patients with high or low performance, locales of greater prefrontal activation and locales of less activation were found in the high-performing patients but only locales of underactivation were found in the low-performing patients.