Grant Report on Social Reward Learning in Schizophrenia

Abstract

We report on the ongoing R21 project "Social Reward Learning in Schizophrenia". Impairments in social cognition are a hallmark of schizophrenia. However, little work has been done on social reward learning deficits in schizophrenia. The overall goal of the project is to assess social reward learning in schizophrenia. A probabilistic reward learning (PRL) task is being used in the MRI scanner to evaluate reward learning to negative and positive social feedback. Monetary reward learning is used as a comparison to assess specificity. Behavioral outcomes and brain areas, included those involved in reward, are assessed in patients with schizophrenia or schizoaffective disorder and controls. It is also critical to determine whether decreased expected value (EV) of social stimuli and/or reward prediction error (RPE) learning underlie social reward learning deficits to inform potential treatment pathways. Our central hypothesis is that the pattern of social learning deficits is an extension of a more general reward learning impairment in schizophrenia and that social reward learning deficits critically contribute to deficits in social motivation and pleasure. We hypothesize that people with schizophrenia will show impaired behavioral social reward learning compared to controls, as well as decreased ventromedial prefrontal cortex (vmPFC) EV signaling at time of choice and decreased striatal RPE signaling at time of outcome, with potentially greater impairment to positive than negative feedback. The grant is in its second year. It is hoped that this innovative approach may lead to novel and more targeted

Reduced motivation for social contact in Disrupted-in-schizophrenia transgenic rats

“…It is plausible to assume that this was the result of altered DA signalling in the brain, in particular in the Developmentally, previous results (Djouma et al, 2006) on the modification (increase in binding) of D2 receptor density by the change in the social environment (social isolation), the role of DAT levels in the regulation of social behaviors (by DAT knockout of mice), (Morgan et al, 2002), and the highlighted interplay of regular social contact and striatal function (Fone and Porkess, 2008), all suggest that striatal DA signaling is critical for proper social interactions. Behaviorally, the tgDISC1s rats' reduced motivation to seek out juvenile conspecifics interaction opportunities aligns with previous studies with neuropsychiatric patients who revealed similar dissocations between social and non-social reward processing (Gotts et al, 2012;Lee et al, 2019;Butler et al, 2020). For example, patients with schizophrenia may experience impairment and disconnection between several components of social motivation required for interactions with positive social outcomes.…”

“…previous studies with neuropsychiatric patients who revealed similar dissocations between social and non-social reward processing (Gotts et al, 2012;Lee et al, 2019;Butler et al, 2020). For example, patients with schizophrenia may experience impairment and disconnection between several components of social motivation required for interactions with positive social outcomes.…”

Differential deficits in social versus monetary reinforcement learning in schizophrenia: Associations with facial emotion recognition.

“…Lee et al, 2019). Part of this divergence of results could be because, as outlined in Butler et al (2020), the current study optimized the PRL paradigm from the original version so that: (a) participants could perform behaviorally at above-chance levels and (b) HCs would perform equally well on the social and monetary task conditions. Thus, it is possible that participants using the original version of the paradigm as in the aforementioned studies may have been unable to perform much above chance levels on the PRL which may have mitigated the ability to find behavioral differences between groups.…”

“…Another possible limitation of the current work is that the social feedback came in the form of static pictures of happy, angry, or neutral faces. Although these faces and expressions had been piloted prior to running the task (Butler et al, 2020), it is possible that they may not reflect the more dynamic and complex social cues in the real world which may be associated with additional behavioral consequences in participants' daily lives.…”