title: An fMRI investigation of delay discounting in patients with schizophrenia.
abstract: Schizophrenia (SZ) is associated with a reduced ability to set meaningful goals to reach desired outcomes. The delay-discounting (DD) task, in which one chooses between sooner smaller and later larger rewards, has proven useful in revealing executive function and reward deficits in various clinical groups. We used fMRI in patients with SZ and healthy controls (HC) to compare brain activation during performance of a DD task. Prior to the neuroimaging session, we obtained each participant's rate of DD, k, on a DD task and used it to select a version of the DD task for each participant's fMRI session. Because of the importance of comparing fMRI results from groups matched on performance, we used a criterion value of R (2) > 0.60 for response consistency on the DD task to analyze fMRI activation to DD task versus control trials from consistent SZ (n = 14) and consistent HC (n = 14). We also compared activation between the groups on contrasts related to trial difficulty. Finally, we contrasted the inconsistent SZ (n = 9) with the consistent HC and consistent SZ; these results should be interpreted with caution because of inconsistent SZ's aberrant performance on the task. Compared with consistent HC, consistent SZ showed reduced activation to DD task versus control trials in executive function and reward areas. In contrast, consistent SZ showed more activation in the precuneus and posterior cingulate, regions of the default mode network (DMN) that are typically deactivated during tasks, and in the insula, a region linked to emotional processing. Furthermore, consistent SZ had abnormal activation of lateral and medial frontal regions in relation to trial difficulty. These results point to disruption of several neural networks during decision making, including the executive, reward, default mode, and emotional networks, and suggest processes that are impaired during decision making in schizophrenia.
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-0017 ; Department of Psychology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-1170.
authors.forename: Kathy Burton
authors.initials: KB
authors.lastname: Avsar
authors.affiliation: Department of Psychology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-1170.
authors.forename: Rosalyn Eve
authors.initials: RE
authors.lastname: Weller
authors.affiliation: Department of Psychology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-1170.
authors.forename: James Edward
authors.initials: JE
authors.lastname: Cox
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-0017 ; Department of Biomedical Engineering, The University of Alabama at Birmingham Birmingham, Alabama, 35294-2182.
authors.forename: Meredith Amanda
authors.initials: MA
authors.lastname: Reid
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-0017.
authors.forename: David Matthew
authors.initials: DM
authors.lastname: White
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-0017.
authors.forename: Adrienne Carol
authors.initials: AC
authors.lastname: Lahti
keywords: Delay discounting; executive function; intertemporal; reward; schizophrenia; subjective value