Functional connectivity in a monetary and social incentive delay task in medicated patients with schizophrenia

Abstract

Introduction: Numerous studies indicate impaired reward-related learning in individuals with schizophrenia, with various factors such as illness duration, medication, disease severity, and level of analysis (behavioral or neurophysiological data) potentially confounding the results. Patients with schizophrenia who are treated with second-generation antipsychotics have been found to have a less affected reward system. However, this finding does not explain the neural dysfunctions observed in previous studies. This study aimed to address the open question of whether the less impaired reward-related behavior is associated with unimpaired task-related functional connectivity or altered task-related functional connectivity.

Methods: The study included 23 participants diagnosed within the schizophrenia spectrum and 23 control participants matched in terms of age, sex, and education. Participants underwent an MRI while performing a monetary incentive delay task and a social incentive delay task. The collected data were analyzed in terms of behavior and functional connectivity.

Results: Both groups exhibited a main effect of reward type on behavioral performance, indicating faster reaction times in the social incentive delay task, but no main effect of reward level. Altered functional connectivity was observed in predictable brain regions within the patient group, depending on the chosen paradigm, but not when compared to healthy individuals.

Discussion: In addition to expected slower response times, patients with schizophrenia demonstrated similar response patterns to control participants at the behavioral level. The similarities in behavioral data may underlie different connectivity patterns. Our findings suggest that perturbations in reward processing do not necessarily imply disturbances in underlying connectivities. Consequently, we were able to demonstrate that patients with schizophrenia are indeed capable of exhibiting goal-directed, reward-responsive behavior, although there are differences depending on the type of reward.

Keywords: fMRI; functional connectivity; monetary incentive delay (MID) task; schizophrenia; social incentive delay (SID) task.

Figure 1

Experimental paradigm.

Figure 2

(A) Reaction times of patients diagnosed with schizophrenia (SZ) and community sample (CS) for monetary incentive delay tasks (MID) and social incentive delay tasks (SID). (B) Hit rates of patients diagnosed with schizophrenia (SZ) and the community sample (CS) for monetary incentive delay tasks (MID) and social incentive delay tasks (SID). Error bars indicate standard error (S.E.). Significant comparisons of means within the group and reward type are indicated by asterisks (pairwise t-test: *p < 0.05).

Figure 3

SZ MID > SID [functional network connectivity (FNC); seed analysis, ROI-to-ROI connections; connectome ring display]. Only ROIs with a positive or negative significant connection to one of the seeds (p-FDR < 0.05) are labeled. Seeds with significant connections: ACC [ACC—anterior cingulate cortex, FP—frontal pole, IC—insular cortex, pSMG—posterior supramarginal gyrus, pSTG–posterior supratemporal gyrus].

Figure 4

SZ > CS—MID [functional network connectivity (FNC); seed analysis, ROI-to-ROI connections; connectome ring display]. Only ROIs with a positive or negative significant connection to one of the seeds (p-FDR < 0.05) are labeled. Seeds with significant connections: SMA right, aSMG left, pallidum left, SMA left [CO—central opercular cortex, IC—insular cortex, SFG—superior frontal gyrus, SMA—supplementary motor areal, aSMG—anterior supramarginal gyrus].