Abstract
Brain reward processing mechanisms that underlie complex decision-making are compromised in psychosis. The goal of this research was to advance our understanding of the underlying (1) neural mechanisms and (2) discrete neuro-economic/motivational processes that may be altered in complex decision-making in euthymic patients on the psychosis spectrum (PPS). Utilizing a functional magnetic resonance neuroimaging (fmri) paradigm of a well-validated laboratory measure of complex decision-making (Iowa Gambling Task-IGT), the brain activation patterns of a target group of PPS were compared to a demographically matched healthy comparison group (HMC). These two groups were also evaluated on real-life decision outcomes on day of scan. PPS primarily activate the Dorsal Attentional Network (DAN) in real-life decision outcomes and in achieving similar levels of performance on the IGT as the HMC, in-spite of dysregulated dopamine-based brain-reward circuit and salience network fmri activation patterns. However, PPS report more significant negative outcomes of their decision-making in real-life, compared to HMC. The differential engagement of brain networks by PPS on the IGT appear to be moderated by antipsychotic, dopamine antagonist, medication lifetime/daily dose levels. These findings may also be mediated by extent of dysregulation in brain reward circuitry and salience network associated with psychosis severity in the target PPS group. This is also evident in case studies of unmedicated PPS. We conclude by suggesting that the brain may adapt to this dysregulation by co-opting the DAN network, which is implicated in the related function of problem-solving, towards complex decision-making. The extent of utilization of the DAN network in complex decision-making may be moderated by psychosis severity.
Highlights
Psychosis and dopamine brain reward circuitry mechanisms in the brain [1] and there is fair consensus in the literature identifying the components of reward processing in health and disease [2, 3], in complex decision-making(CDM) [4,5,6]
The dopamine hypotheses of psychosis posit that dysregulation in dopamine-based reward circuit mechanisms lead to psychotic symptoms involving (1) subcortical hyperdopaminergia (2) prefrontal hypodopaminergia compromising top-down cognitive control networks; and (3) aberrant salience attribution (“the third dopamine hypothesis”) [12] involving dysregulation of the salience network as well [13]
While the above results track brain reward circuit function in vivo through fmri, we examined how this may be translated in real-life behavior
Summary
Psychosis and dopamine brain reward circuitry mechanisms in the brain [1] and there is fair consensus in the literature identifying the components of reward processing in health and disease [2, 3], in complex decision-making(CDM) [4,5,6]. These include reward valuation/prediction and expectancy that drives selection or subjective choice; and initial or extended responsiveness to reward attainment (Win); generation of a reward prediction error signal in outcome processing of Lose; and updating mechanisms for adaptive reward learning. The dopamine hypotheses of psychosis posit that dysregulation in dopamine-based reward circuit mechanisms lead to psychotic symptoms involving (1) subcortical hyperdopaminergia (dopamine overdrive) (2) prefrontal hypodopaminergia (hypo-frontality) compromising top-down cognitive control networks; and (3) aberrant salience attribution (“the third dopamine hypothesis”) [12] involving dysregulation of the salience network as well [13]
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