Development Of Cognitive Activation Tasks For Functional

National Institute Of Mental Health

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Abstract

We have developed a variety of tasks to activate regions of interest in functional neuroimaging studies. 1. To examine the levels of processing account of episodic memory we devised a series or recognition memory tasks. We also paid special attention to the development of a control task that would not involve active processing so as to better observe hippocampal activation. Preliminary results indicate marked prefrontal cortical activations during higher level encoding and hippocampal activations during encoding and retrieva. 2. We developed a Continuous Performance Test of attention and encoding to be used in event related fMRI. While behavioral deficits have been widely reported in schizophrenic patients, the neural substrate of this task has yet to be elucidated. Toward this end we degraded stimuli and used only the letters x and y so each individual trial in an event related paradigm was informative. 3. We developed a carefully matched set of verbal fluency tasks to examine the relation between semantic processing, thought disorder, and neurophysiology in schizophrenia using PET CBF methods. We are also using a semantic processing task in fMRI to determine the physiologic concomitants of repetition priming versus conceptual priming in order to ascertain whether semantic access is automatic and if the two tasks involve similar functional neuroanatomies.