Schizophrenia Subjects Show Intact Success-Related Neural Activation but Impaired Uncertainty Processing during Decision-Making

Abstract

Decision-making is a complex process that is important for everyday life. This study examined the effect of the degree of success, and outcome uncertainty, on decision-making and associated neural substrate activation in schizophrenia subjects (SZS) and normal comparison subjects (NCS). A total of 15 subjects with a diagnosis of schizophrenia and 15 age-and education-matched NCS participated in this study. These subjects completed the two-choice prediction task during functional magnetic resonance imaging. Decision-making characteristics and activation of neural substrates were obtained at 20, 50, or 80% error rate. Success and uncertainty influenced the behavioral characteristics on the two-choice prediction task, and the task-related activation in SZS and NCS. Neither success nor uncertainty differentially affected the behavioral characteristics of SZS relative to NCS during the two-choice prediction task. Nonetheless, there was a significant interaction between group and error rate in bilateral parietal cortex. The activation in NCS was the highest when the outcome was most uncertain. In contrast, task-related activation in SZS was not modulated by the degree of uncertainty. Thus, SZS failed to utilize the parietal cortex to process decision-making situations with highly uncertain outcomes.

Practice, learning, and the likelihood of making an error: how task experience shapes physiological response in patients with schizophrenia

“…The cingulate is modulated by dopaminergic input and midbrain dopamine neurons are thought to be crucial in conditioned, reward-predictive learning (Schultz 2002). It is reasonable to investigate changes in midbrain and cingulate systems during conflictual tasks, those in which error and/or reward are unpredictable (Botvinick et al 1999;Gehring and Fencsik 2001;Alain et al 2002;Ruchsow et al 2002;Holroyd and Coles 2002;Schultz 2002;Paulus et al 2003). Midbrain dopamine projections also extend throughout the frontal lobe.…”

“…Alain et al (2002) and Mathalon et al (2002) describe abnormalities in the schizophrenic subjects' generation of error-related negative potentials during the Stroop and a picture-word matching task, respectively. Paulus et al (2003) describes a marked difference in the parietal cortex response to uncertainty in schizophrenic vs healthy control subjects (controls show high parietal activity during uncertain decisions whereas schizophrenic volunteers do not). Each study emphasizes the role of uncertainty or error, and each study provides strong evidence for an inability of the schizophrenic subject to engage appropriate neural systems when an error is either committed or likely to be committed.…”

“…The electrophysiological studies indicate the error detection failure is most likely associated with anterior cingulate dysfunction. Paulus et al (2003) explains that controls making a visual two-choice prediction generate maximal activity in the parietal cortex when the choice is uncertain. Schizophrenic subjects do not engage this structure any more during uncertain trials than during those in which no choice is needed.…”

“…This, in turn, is consistent with Holcomb et al (2000) who demonstrated a failure in this structure's activity when schizophrenics switched from a low to a high cognitive demand task. The study by Paulus et al (2003) also serves to emphasize that multiple cortical structures are operant in cognitive behavior associated with error and uncertainty. It also provides evidence from a different temporal scale than seen with evoked potentials since fMRI reveals phenomena over seconds and electrophysiological data capture data on the millisecond level.…”

Impaired Activation in Cognitive Control Regions Predicts Reversal Learning in Schizophrenia

“…20 Dorsal parietal cortex regions (DPC) have been implicated in value representation and switching. 21 Importantly, SZ patients have structural (dlPFC 22,23 , ACC 24 , DPC 25 ), and functional deficits (dlPFC [26][27][28] , ACC 29,30 , PC 31,32 ) in these regions. However, the relationship of the CCN to value representations in SZ has not been tested.…”