Understanding Executive Function and Dysfunction in Schizophrenia through Cortical Oscillatory Dynamics

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Cognitive performance is viewed as essential to daily psychosocial function in schizophrenia, with executive function (EF) considered one of the most critical areas of deficit. Understanding the nature of EF deficits and their role in manifest psychopathology is still considered as limited, handicapped by problems of concept and method. Hemodynamic and electromagnetic imaging results in healthy individuals and schizophrenia patients have suggested brain regions and activity patterns as involved in EF, but the mechanism of translation of neuronal network communication into EF remains unclear. Understanding mechanisms seem critical to understanding dysfunctional EF in schizophrenia. The proposed project seeks to identify and model mechanisms supporting EF by mapping neuronal network communication via oscillatory dynamics in healthy individuals and schizophrenia patients. Magneto- and electroencephalographic activity will be monitored in tasks selected to activate EF, and advanced methods are combined for mapping oscillatory dynamics. Hypotheses include (1) oscillatory dynamics are key in communication between (global) and within (local) function-specific neuronal circuits spanning prefrontal and posterior regions subserving EF, (2) neuronal synchrony between defined regions reflects an active sampling mechanism thought to be fundamental in coordinated processes, (3) task-related dynamics vary with baseline state such that patterns of task-related brain function and behavioral performance can be predicted, (4) the relationship between ongoing and task-related oscillatory dynamics is disrupted in schizophrenia, contributing to deficient active sampling capacity and deficient EF. Task selection is based on EF taxonomies and published recommendations for distinguishing relevant facets of EF, on evidence connecting MEG and EEG measures to the working memory maintenance and interference control facets of EF on which we focus here, and on evidence from our work supporting the hypothesis of oscillatory dynamics as a manifestation of the respective functions. We expect this work to support conceptual modeling of the nature and organization of EF, to clarify the role of oscillatory activity in both normal and abnormal cognition, and to improve understanding of disruption in neuronal network communication in schizophrenia associated with dysfunctional cognition. This will in turn support modeling of the critical oscillatory dynamics potentially fundamental to the development of schizophrenia psychopathology. Such findings would have both diagnostic and therapeutic applications.