INCREASED PREFRONTAL CORTEX ACTIVATION IN SCHIZOPHRENIA FOLLOWING COGNITIVE TRAINING USING THE AX-CPT. Natalie Badowski1, Deanna Barch2, Biology Department, Washington University, St. Louis, MO1, Psychology Department, Washington University, St. Louis, MO2.
Schizophrenia is a form of psychopathology characterized by deficits in the goal-directed regulation of thoughts and actions, functions that are widely believed to be dependent on the intercommunication of the prefrontal cortex (PFC), the anterior cingulate cortex (ACC), and on the midbrain dopamine (DA) projections. The Dual Mechanisms of Control (DMC) model suggests that these neural systems provide two modes of cognitive control: a proactive one that enables the maintenance of contextual information to prepare for a future response and shows sustained activity in the lateral PFC; and a reactive mode that provides a last-minute interference resolution for context retrieval, resulting in transient activity in the lateral PFC, the ACC, and in other brain systems. Using the AX version of the Continuous Performance Test (AX-CPT) and fMRI neuroimaging to selectively measure the behavioral and neural correlates of both proactive and reactive control, previous studies with healthy older adults have suggested that proactive control could be enhanced with focused training that promotes the tendency to use contextual cues to predict subsequent stimuli. Here, the task and training was extended to schizophrenia patients with the hypothesis that focus training would enhance proactive control, behaviorally and biologically, creating increased sustained activation of the right lateral PFC and decreased transient activation of the PFC, ACC, and other brain areas.
An initial analysis of the behavioral data suggests that a number of individuals with schizophrenia are able to use cognitive training to improve their performance on the AX-CPT. These subjects show a reduction in BX errors (caused by context processing failures indicating a reactive response) and an increase in AY errors (errors induced by good context processing and proactive planning). However, compared to older adults, the ability to benefit from this training is not as robust across subjects and is not as large in magnitude. Analyses of the fMRI data will focus on regions of the dorsolateral prefrontal cortex and the inferior frontal junction. In previous studies, these areas have displayed changes in the dynamics of brain activity as a function of training in older adults, and have been known to be particularly critical for context processing.