Effort, avolition and motivational experience in schizophrenia: Analysis of behavioral and neuroimaging data with relationships to daily motivational experience
Recent research has suggested an association between motivational impairment in those with schizophrenia and reduced willingness to expend effort on experimental tasks. However, few studies have examined the neural correlates of effort-based decision-making in those with schizophrenia. In the current study, we aimed to examine willingness to expend effort, the associated neural circuitry of effort-based decision-making, and the impact of experimentally-defined effort-based decision-making on daily motivational experience in schizophrenia. We recruited 28 individuals with schizophrenia and 30 healthy controls to perform an effort-based decision-making task while undergoing fMRI scanning. In order to assess whether willingness to expend effort was associated with daily motivational experience, individuals with schizophrenia also completed short surveys over a weeklong period, outside the lab. Similar to previous reports, we found that individuals with schizophrenia were less willing than healthy controls to expend effort to obtain rewards. Further, we found participants with schizophrenia with the greatest negative symptom severity, as measured by clinician-interview, were the least willing to exert effort. When looking at daily assessment of motivation outside the lab, this negative symptom effect was trend-level significant. In neuroimaging, both individuals with schizophrenia and healthy controls displayed similarly robust increases in BOLD activation in frontal, cingulate, parietal, and insular regions during effort-based decision-making, and group differences were not observed. However, clinician-rated negative symptoms showed robust associations with reduced BOLD activation in bilateral ventral striatum during decision-making and greater discounting was associated with increased insula activity at a nominal significance level. These results provide replication of previously reported reductions of effort allocation in those with schizophrenia with severe negative symptoms, and provide preliminary evidence for the role of ventral striatum in such behavioral impairments
