Development Of Cognitive Activation Tasks For Functional

National Institute Of Mental Health

Investigators

Linked publications, trials & patents

Abstract

We have developed a variety of tasks to activate regions of interest in functional neuroimaging studies. 1. To examine the distinction between recall and familiarity in episodic memory function we have developed a task using visual scenes that reliably induces familiarity based errors in controls. 2. We assessed the role of Catecol-O-methyltransferase(COMT) genotype in a functional Magnetic Resonance Imaging (fMRI) event related study which gauged the effects of cognitive control on various conditions involving interference in the so called flanker task. 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 (Positron Emission Tomography Cerebral Blood Flow) methods. We found an area in inferior prefrontal cortex (PFC) that was more activated in semantic fluency and correlated with a classic symptom of schizophrenia -- thought disorder. 4. We are using a novel updating task which allows the amount of "updating" to be varied parametrically by demanding operations on single or multiple frames within each trial. This technique will allow us to examine whether there is an interaction between load and delay in the dorsolateral prefrontal cortex and how and whether such interactions may engage different subdivisions within the prefrontal cortex. 5. We are exploring the effects of the functional COMT val158met polymorphism on anterior cingulate while engaged in a novel attentional control task. The task will allow us to compare the allelic effect, val/val, val/met, and met/met on signal-to-noise ratio and dopaminergic tone in the frontal cortex. It is presumed that the met load enhances the dopaminergic effect which may in turn improve the efficiency of the local circuit processing within the cingulate cortex and its function during attentional control. 6. We performed a study aimed at investigating the role of the inferior prefrontal cortex (IPFC) by using a semantic triadic decision-making task during fMRI. The IPFC is critical for processing competing semantic information when making a decision about the meaning of a stimulus. The specific role of the IPFC in this process is unclear, whether it is maintaining or creating a semantic organizational structure. 7. We conducted an event-related functional magnetic resonance imaging (fMRI) study using a task preferentially involving interference monitoring and suppression or response inhibition. Our findings compared the two conditions which indicated greater activation bilaterally in the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex and parietal cortex during response inhibition and greater activation in the dorsal cingulate during interference monitoring and suppression extending previous findings by suggesting regional functional specialization within a cortical network supporting cognitive control.