ITR: High-Resolution Cortical Imaging of Brain Electrical Activity

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0218736HeThe past decade, dubbed the "Decade of the Brain", has witnessed explosive growth in the ability to observe and measure brain activity in human subjects. The technique of functional magnetic resonance imaging (fMRI) has enabled precise anatomical localization of brain structures that are activated during certain psychological processes. Though fMRI has high spatial resolution, temporal resolution is on the order of a second. In contrast, electrophysiological (EEG type) recordings, which can be obtained from the scalp and measure the electrical activity of ensembles of neurons activated synchronously (event-related potentials (ERP) provide millisecond level temporal resolution but limited spatial resolution. Tremendous efforts have been made to localize electrical source generators within the brain that underlie ERP components evoked by specific sensory, motor, or cognitive events. The approach, called electrophysiological neuroimaing, attempts to image the neural source distribution within the brain from electophysiological recordings obtained over the scalp by deconvolving the volume conduction process. The focus of this proposal is to achieve high spatial and temporal resolution in brain imaging by mathematically combining MRI and EEG data. The method involves placing constraints derived from one imaging modality on possible inverse solutions of the other modality. Once the algorithms are developed, the method will be applied to obtaining finer localization of brain structures involved in detecting and responding to an error in a cognitive task. The multimodal brain imaging technique will be assessed for applicability and performance in studying executive control systems in healthy subjects and disturbance of executive functions in selected groups of patients with schizophrenia.