Abnormal Responses to Monetary Outcomes in Cortex, but not in the Basal Ganglia, in Schizophrenia

Abstract

Psychosis has been associated with aberrant brain activity concurrent with both the anticipation and integration of monetary outcomes. The extent to which abnormal reward-related neural signals can be observed in chronic, medicated patients with schizophrenia (SZ), however, is not clear. In an fMRI study involving 17 chronic outpatients with SZ and 17 matched controls, we used a monetary incentive delay (MID) task, in which different-colored shapes predicted gains, losses, or neutral outcomes. Subjects needed to respond to a target within a time window in order to receive the indicated gain, or avoid the indicated loss. Group differences in BOLD responses to cues and outcomes were assessed through voxel-wise whole-brain analyses and regions-of-interest analyses in the neostriatum and prefrontal cortex (PFC). Significant group by outcome valence interactions were observed in medial and lateral PFC, lateral temporal cortex, and the amygdalae, such that controls, but not patients, showed greater activation for gains, relative to losses. In the striatum, neural activity was modulated by outcome magnitude in both groups. Additionally, we found that ratings of negative symptoms in patients correlated with sensitivity to obtained losses in medial PFC, obtained gains in lateral PFC, and anticipated gains in left ventral striatum. Sensitivity to obtained gains in lateral PFC also correlated with positive symptom scores in patients. Our findings of systematic relationships between clinical symptoms and neural responses to stimuli associated with rewards and punishments offer promise that reward-related neural responses may provide sensitive probes of the effectiveness of treatments for negative symptoms.

Ventral Striatal Dysfunction and Symptom Expression in Individuals With Schizotypal Personality Traits and Early Psychosis

“…[19][20][21][22] In contrast, there is now meta-analytic support for reduced VS activation in patients with established schizophrenia, 24 but results on the individual study level are very inconsistent. 15,16,23,25,31,35,59,62,63 These mixed findings support the notion that striatal alterations in psychosis do not solely consist of hypo-activation but vary between different stages (early vs chronic) and different forms of psychosis (schizophrenia vs non-schizophrenia). In line with this notion, patients with FEP-SZ showed higher striatal activity compared to other individuals within the psychosis continuum.…”

“…52 At the neural level, the observed positive correlation of apathy and increased VS activity contrasts with previous studies, including our own, reporting a negative association in patients with schizophrenia. 25,26,35 However, the studies showing an association of striatal hypoactivation and apathy were typically based on samples with more primary negative symptoms in patients with chronic schizophrenia. 25,26 In contrast, the current study investigated a psychosis continuum from nonclinical participants to patients with early psychosis with a different psychopathological construct of apathy (partly secondary to positive and depressive symptoms).…”

“…Based on previous studies discussed above, 19,21,23,25,35 we expected symptom expression but not group membership to be associated with aberrant ventral striatal activity during reward anticipation.…”

Anorexia Nervosa and Obesity are Associated with Opposite Brain Reward Response

“…Some other studies investigated the dopamine model-related brain response in psychiatric disorders, such as depression (Kumar et al, 2008) or schizophrenia (Waltz et al, 2010), and tended to find reduced brain response in those disorders. Dopamine neuronal reward response can be captured in an algorithm that takes advantage of dopamine neurons responding to unexpected reward stimulus receipt or omission (Schultz, 2002).…”

An electrophysiological monetary incentive delay (e-MID) task: A way to decompose the different components of neural response to positive and negative monetary reinforcement

“…While in contrast, chronic cannabis users are found to exhibit exaggerated right ventral striatum activation during the anticipation of incentives (Nestor, et al, 2010). On the other hand, following informative feedback relevant to reinforcement outcome, activation of reward-related brain circuitry to monetary gain is found to be increased in patients with ADHD (Ströhle et al, 2008) and substance dependent patients (Bjork, et al, 2008); while activation of reward related brain areas in patients with schizophrenia (Waltz, et al, 2010), patients with autism spectrum disorder (Dichter, et al, 2012) and patients with major depressive disorder (Pizzagalli, et al, 2009) is found to be decreased. The differences between and within mental disorders in the activation of reward-related brain regions during anticipatory and reward receipt stages underscore the importance of using tasks like the fMRI MID to dissociate the neural response associated with each stage of reinforcement processing.…”