Altered cingulo-striatal function underlies reward drive deficits in schizophrenia

Reward Learning as a Potential Mechanism for Improvement in Schizophrenia Spectrum Disorders Following Cognitive Remediation: Protocol for a Clinical, Nonrandomized, Pre-Post Pilot Study

BACKGROUND

Cognitive impairment is common with schizophrenia spectrum disorders. Cognitive remediation (CR) is effective in improving global cognition, but not all individuals benefit from this type of intervention. A better understanding of the potential mechanism of action of CR is needed. One proposed mechanism is reward learning (RL), the cognitive processes responsible for adapting behavior following positive or negative feedback. It is proposed that the structure of CR enhances RL and motivation to engage in increasingly challenging tasks, and this is a potential mechanism by which CR improves cognitive functioning in schizophrenia.

OBJECTIVE

Our primary objective is to examine reward processing in individuals with schizophrenia before and after completing CR and to compare this with a group of matched clinical controls. We will assess whether RL mediates the relationship between CR and improved cognitive function and reduced negative symptoms. Potential differences in social RL and nonsocial RL in individuals with schizophrenia will also be investigated and compared with a healthy matched control group.

METHODS

We propose a clinical, nonrandomized, pre-post pilot study comparing the impact of CR on RL and neurocognitive outcomes. The study will use a combination of objective and subjective measures to assess neurocognitive, psychiatric symptoms, and neurophysiological domains. A total of 40 individuals with schizophrenia spectrum disorders (aged 18-35 years) will receive 12 weeks of CR therapy (n=20) or treatment as usual (n=20). Reward processing will be evaluated using a reinforcement learning task with 2 conditions (social reward vs nonsocial reward) at baseline and the 12-week follow-up. Functional magnetic resonance imaging responses will be measured during this task. To validate the reinforcement learning task, RL will also be assessed in 20 healthy controls, matched for age, sex, and premorbid functioning. Mixed-factorial ANOVAs will be conducted to evaluate treatment group differences. For the functional magnetic resonance imaging analysis, computational modeling will allow the estimation of learning parameters at each point in time, during each task condition, for each participant. We will use a variational Bayesian framework to measure how learning occurred during the experimental task and the subprocesses that underlie this learning. Second-level group analyses will examine how learning in patients differs from that observed in control participants and how CR alters learning efficiency and the underlying neural activity.

RESULTS

As of September 2023, this study has enrolled 15 participants in the CR group, 1 participant in the treatment-as-usual group, and 11 participants in the healthy control group. Recruitment is expected to be completed by September 2024. Data analysis is expected to be completed and published in early 2025.

CONCLUSIONS

The results of this study will contribute to the knowledge of CR and RL processes in severe mental illness and the understanding of the systems that impact negative symptoms and cognitive impairments within this population.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/52505.

Revisiting reward impairments in schizophrenia spectrum disorders: a systematic review and meta-analysis for neuroimaging findings

BACKGROUND

Abnormal reward functioning is central to anhedonia and amotivation symptoms of schizophrenia (SCZ). Reward processing encompasses a series of psychological components. This systematic review and meta-analysis examined the brain dysfunction related to reward processing of individuals with SCZ spectrum disorders and risks, covering multiple reward components.

METHODS

After a systematic literature search, 37 neuroimaging studies were identified and divided into four groups based on their target psychology components (i.e. reward anticipation, reward consumption, reward learning, effort computation). Whole-brain Seed-based d Mapping (SDM) meta-analyses were conducted for all included studies and each component.

RESULTS

The meta-analysis for all reward-related studies revealed reduced functional activation across the SCZ spectrum in the striatum, orbital frontal cortex, cingulate cortex, and cerebellar areas. Meanwhile, distinct abnormal patterns were found for reward anticipation (decreased activation of the cingulate cortex and striatum), reward consumption (decreased activation of cerebellum IV/V areas, insula and inferior frontal gyri), and reward learning processing (decreased activation of the striatum, thalamus, cerebellar Crus I, cingulate cortex, orbitofrontal cortex, and parietal and occipital areas). Lastly, our qualitative review suggested that decreased activation of the ventral striatum and anterior cingulate cortex was also involved in effort computation.

CONCLUSIONS

These results provide deep insights on the component-based neuro-psychopathological mechanisms for anhedonia and amotivation symptoms of the SCZ spectrum.

A transdiagnostic meta-analysis of physical and social Anhedonia in major depressive disorder and schizophrenia spectrum disorders

INTRODUCTION

Anhedonia is a transdiagnostic construct conceptualized as physical or social, however, the extent to which these subtypes differ across psychotic and mood pathology remains poorly understood. We aimed to quantify the severity of physical and social anhedonia across Major Depressive Disorder (MDD) and Schizophrenia Spectrum Disorder (SSDs).

METHODS

We conducted meta-analyses of the Chapman Physical and Social Anhedonia Scales (PAS;SAS). We reviewed data from participants with MDD, and SSDs separately.

RESULTS

Our first meta-analysis (n = 8 studies, 409 participants) with MDD revealed elevated SAS and PAS in MDD compared to controls. Within-group differences were not significant. Depressive symptom severity moderated the between-group effect of PAS. Our second meta-analysis (n = 44 studies, 3352 participants) revealed elevated SAS and PAS in SSDs compared to controls. We detected a moderate difference between the SAS and PAS within the SSD group. Age moderated within-group differences of SAS and PAS.

DISCUSSION

People with SSD or MDD experience elevated SAS and PAS compared to controls. People with SSDs endorse greater challenges experiencing social rewards relative to physical rewards. People with MDD experience social and physical rewards similarly. The moderating role of depressive symptoms in MDD suggests that physical anhedonia is more state-like than social anhedonia.

The Transdiagnostic Nature of Social Anhedonia: Historical and Current Perspectives

In this chapter, we trace the historical roots of the social anhedonia (SoA) construct to current conceptualizations. We first describe the aspects of SoA that distinguish it from anhedonia in general. We summarize evidence that SoA is a transdiagnostic symptom and risk factor. Although several forms of psychopathology are associated with elevated rates of self-reported SoA, one unresolved issue is whether the processes and mechanisms underlying SoA in one disorder are the same as the processes and mechanisms underlying SoA seen in another disorder. We assert that there may be different causal factors underlying SoA across disorders. Considering both the principles of equifinality and multifinality, we offer an integrative model for social reward processing. This conceptualization considers roles for the following: attention; social cognition, including, but not limited to, social skills; reward learning and valuation; working memory; anticipation, prediction, and remembering; and motivation and effort. We conclude that SoA may be caused by multiple underlying impairments, all of which may serve as targets for intervention. This conceptualization is provided as an impetus for further research in the area.

Brain activity and connectivity differences in reward value discrimination during effort computation in schizophrenia

Negative symptoms in the motivational domain are strongly correlated with deficits in social and occupational functioning in schizophrenia. However, the neural substrates underlying these symptoms remain largely unknown. Twenty-eight adults with schizophrenia and twenty healthy volunteers underwent functional magnetic resonance while completing a lottery game designed to capture reward-related cognitive processes. Each trial demanded an initial investment of effort in form of key presses to increase the odds of winning. Brain activity in response to different reward cues (1 euro versus 1 cent) was compared between groups. Whereas controls invested more effort in improving their chances to win 1 euro compared to 1 cent in the lottery game, patients invested similarly high amounts of effort in both reward conditions. The neuroimaging analysis revealed lower neural activity in the bilateral caudate and cingulo-opercular circuits and decreased effective connectivity between reward-associated areas and neural nodes in the frontoparietal and salience network in response to high- versus low-reward conditions in schizophrenia patients compared to controls. Effective connectivity differences across conditions were associated with amotivation symptoms in patients. Overall, our data provide the evidence of alterations in neural activity in the caudate and cingulo-opercular "task maintenance" circuits and frontoparietal effective connectivity with reward-associated nodes as possible underlying mechanisms of reward value discrimination deficits affecting effort computation in schizophrenia.

Revisiting anticipatory hedonic processing in patients with schizophrenia: An examination between representation activation and maintenance

BACKGROUND

Anticipatory anhedonia is one of the key deficits found in patients with schizophrenia (SCZ). However, the underlying mechanism of this deficit remains unclear. The present study examined whether representation activation and maintenance capacity influenced anticipatory experiences in SCZ patients.

METHODS

We recruited 46 SCZ patients (26 males) and 45 matched healthy controls (24 males). The Reward Representation Activation and Maintenance (RRAM) Task was administrated to assess anticipatory experience and representation activation and maintenance capacity.

RESULTS

SCZ patients exhibited lower subjective arousal than controls in anticipation of rewards with high probability when representation activation and maintenance were difficult to accomplish. SCZ patients also tended to reduce their button presses more than HC when they were required to maintain reward representation.

CONCLUSIONS

Our findings suggest that representation activation and maintenance may partially account for anticipatory anhedonia observed in SCZ patients.

Reward, Control & Decision-Making in Cannabis Use Disorder: Insights from Functional MRI

The recreational consumption of cannabis has increased significantly across the world with an estimated 180 million people currently using. In the United States, 4.1 million are currently diagnosed with cannabis use disorder. Cannabis dependence and abuse was combined into a single entity as a behavioral disorder with a problematic pattern of cannabis use and termed cannabis use disorder by the Diagnostic and Statistical Manual of Mental Disorders. Chronic use of cannabis has been linked with region-specific effects across the brain mediating reward processing, cognitive control and decision-making that are central to understanding addictive behaviors. This review presents a snapshot of the current literature assessing the effects of chronic cannabis use on human brain function via functional MRI. Studies employing various paradigms and contrasting cognitive activation amongst cannabis users and non-users were incorporated. The effects of trans-del-ta-9-tetrahydrocannabinol (Δ9-THC) in marijuana and other preparations of cannabis are mediated by the endocannabinoid system, which is also briefly introduced.Much variation exists in the current literature regarding the functional changes associated with chronic cannabis use. One possible explanation for this variation is the heterogeneity in study designs, with little implementation of standardized diagnostic criteria when selecting chronic users, distinct time points of participant assessment, differing cognitive paradigms and imaging protocols. As such, there is an urgent requirement for future investigations that further characterize functional changes associated with chronic cannabis use.

Intrinsic mesocorticolimbic connectivity is negatively associated with social amotivation in people with schizophrenia

BACKGROUND

Social amotivation is a core element of the negative symptoms of schizophrenia. However, it is still largely unknown which neural substrates underpin social amotivation in people with schizophrenia, though deficiencies in the mesocorticolimbic dopamine system have been proposed.

METHODS

We examined the association between social amotivation and substantia nigra/ventral tegmental area-seeded intrinsic connectivity in 84 people with schizophrenia using resting state functional magnetic resonance imaging.

RESULTS

Spontaneous fluctuations of midbrain dopaminergic regions were positively associated with striatal and prefrontal fluctuations in people with schizophrenia. Most importantly, social amotivation was negatively associated with functional connectivity between the midbrain's substantia nigra/ventral tegmental area and medial- and lateral prefrontal cortex, the temporoparietal junction, and dorsal and ventral striatum. These associations were observed independently of depressive and positive symptoms.

CONCLUSIONS

Our findings suggest that social amotivation in people with schizophrenia is associated with altered intrinsic connectivity of mesocorticolimbic pathways linked to cognitive control and reward processing. Dysconnectivity of dopaminergic neuronal ensembles that are fundamental to approach behavior and motivation may help explain the lack of initiative social behavior in people with social amotivation.

Disrupted salience processing involved in motivational deficits for real-life activities in patients with schizophrenia

Motivational deficits in patients with schizophrenia adversely affect various domains of daily living. This symptom in everyday life situations manifests in a complex behavioral pattern whose root cannot be simplified to an impaired reward-motivation scheme. This study aimed to identify impairment of the salience network that underlies motivational deficits seen in patients with schizophrenia in real-life situations. During the functional magnetic resonance imaging scan, 20 patients with schizophrenia and 20 normal controls performed a task mimicking real-life situations, in which an avatar proposed participation in a daily activity with either an intrinsic or extrinsic reward. Group and type-of-reward effects were evaluated with respect to brain activity. Further, psychophysiological interactions were analyzed for the dorsal anterior cingulate cortex (dACC) and insula, which are the key nodes of the salience network. The acceptance of the proposal was significantly higher for intrinsic than for extrinsic rewards in controls, whereas patients showed no difference. The imaging results showed a group effect in the dACC, right insula, thalamus, and lingual gyrus. The dACC showed negative contrast interaction with regions of the left dorsolateral prefrontal cortex, and the right insula showed positive contrast interaction with the occipital gyrus and precentral gyrus. These results suggest that patients exhibit no different participation behavior between activities with intrinsic and extrinsic rewards, which can be explained by the floor effect. Disrupted salience processing in schizophrenia including aberrant salience network and a disconnection of the salience and reward networks may account for the lack of motivation for daily activities.

Glutamatergic regulation of cognition and functional brain connectivity: insights from pharmacological, genetic and translational schizophrenia research

The pharmacological modulation of glutamatergic neurotransmission to improve cognitive function has been a focus of intensive research, particularly in relation to the cognitive deficits seen in schizophrenia. Despite this effort, there has been little success in the clinical use of glutamatergic compounds as procognitive drugs. Here, we review a selection of the drugs used to modulate glutamatergic signalling and how they impact on cognitive function in rodents and humans. We highlight how glutamatergic dysfunction, and NMDA receptor hypofunction in particular, is a key mechanism contributing to the cognitive deficits observed in schizophrenia and outline some of the glutamatergic targets that have been tested as putative procognitive targets for this disorder. Using translational research in this area as a leading exemplar, namely, models of NMDA receptor hypofunction, we discuss how the study of functional brain network connectivity can provide new insight into how the glutamatergic system impacts on cognitive function. Future studies characterizing functional brain network connectivity will increase our understanding of how glutamatergic compounds regulate cognition and could contribute to the future success of glutamatergic drug validation. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.

Neural basis of self-initiative in relation to apathy in a student sample

Human behaviour can be externally driven, e.g. catching a falling glass, or self-initiated and goal-directed, e.g. drinking a cup of coffee when one deems it is time for a break. Apathy refers to a reduction of self-initiated goal-directed or motivated behaviour, frequently present in neurological and psychiatric disorders. The amount of undertaken goal-directed behaviour varies considerably in clinical as well as healthy populations. In the present study, we investigated behavioural and neural correlates of self-initiated action in a student sample (N = 39) with minimal to high levels of apathy. We replicated activation of fronto-parieto-striatal regions during self-initiation. The neural correlates of self-initiated action did not explain varying levels of apathy in our sample, neither when mass-univariate analysis was used, nor when multivariate patterns of brain activation were considered. Other hypotheses, e.g. regarding a putative role of deficits in reward anticipation, effort expenditure or executive difficulties, deserve investigation in future studies.

Effort-Based Reinforcement Processing and Functional Connectivity Underlying Amotivation in Medicated Patients with Depression and Schizophrenia

Amotivation is a common phenotype of major depressive disorder and schizophrenia, which are clinically distinct disorders. Effective treatment targets and strategies can be discovered by examining the dopaminergic reward network function underlying amotivation between these disorders. We conducted an fMRI study in healthy human participants and medicated patients with depression and schizophrenia using an effort-based reinforcement task. We examined regional activations related to reward type (positive and negative reinforcement), effort level, and their composite value, as well as resting-state functional connectivities within the meso-striatal-prefrontal pathway. We found that integrated reward and effort values of low effort-positive reinforcement and high effort-negative reinforcement were behaviorally anticipated and represented in the putamen and medial orbitofrontal cortex activities. Patients with schizophrenia and depression did not show anticipation-related and work-related reaction time reductions, respectively. Greater amotivation severity correlated with smaller work-related putamen activity changes according to reward type in schizophrenia and effort level in depression. Patients with schizophrenia showed feedback-related putamen hyperactivity of low effort compared with healthy controls and depressed patients. The strength of medial orbitofrontal-striatal functional connectivity predicted work-related reaction time reduction of high effort negative reinforcement in healthy controls and amotivation severity in both patients with schizophrenia and those with depression. Patients with depression showed deficient medial orbitofrontal-striatal functional connectivity compared with healthy controls and patients with schizophrenia. These results indicate that amotivation in depression and schizophrenia involves different pathophysiology in the prefrontal-striatal circuitry.SIGNIFICANCE STATEMENT Amotivation is present in both depression and schizophrenia. However, treatment involves the use of drugs that enhance serotonin activity in depression and inhibit serotonin and dopamine activity in schizophrenia. Understanding how motivation processed in the mesocorticolimbic and nigostriatal pathways is affected in depression and schizophrenia is important in discovering treatment targets and strategies for amotivation. To our knowledge, this is the first study to compare patients with depression and schizophrenia in a common functional construct. By using an effort-based reinforcement task and examining resting-state functional connectivity in the dopaminergic network, we propose that difference in striato-orbitofrontal dysfunction in effort-based reinforcement between depression and schizophrenia may be related to differences in the extent of functional dysconnectivity in the dopaminergic pathway.

Neural Basis of Anhedonia and Amotivation in Patients with Schizophrenia: The Role of Reward System

Anhedonia, the inability to feel pleasure, and amotivation, the lack of motivation, are two prominent negative symptoms of schizophrenia, which contribute to the poor social and occupational behaviors in the patients. Recently growing evidence shows that anhedonia and amotivation are tied together, but have distinct neural correlates. It is important to note that both of these symptoms may derive from deficient functioning of the reward network. A further analysis into the neuroimaging findings of schizophrenia shows that the neural correlates overlap in the reward network including the ventral striatum, anterior cingulate cortex and orbitofrontal cortex. Other neuroimaging studies have demonstrated the involvement of the default mode network in anhedonia. The identification of a specific deficit in hedonic and motivational capacity may help to elucidate the mechanisms behind social functioning deficits in schizophrenia, and may also lead to more targeted treatment of negative symptoms.

The relationship between self-referential processing-related brain activity and anhedonia in patients with schizophrenia

Despite the possible relationship between impaired self-referential processing and anhedonia, it has not yet been investigated. This study investigated an abnormality in brain activation associated with self-referential processing and its relationship with anhedonia in schizophrenia, specifically in self-related brain regions of interest. Twenty patients with schizophrenia and 25 controls underwent functional magnetic resonance imaging while rating the degree of relevance between faces (self, familiar other, or unfamiliar other) and words (positive, negative, or neutral). Brain activation in self-related regions, including the ventral and dorsal medial prefrontal cortices, anterior cingulate cortex (ACC), posterior cingulate cortex, precuneus, and insula, were compared between groups and their correlations with anhedonia level were calculated. Compared to controls, patients were less likely to rate negative words as irrelevant for the self face. Patients showed significantly increased activation in the ACC and precuneus compared to controls, irrespective of conditions. ACC activity in the self-neutral word condition was positively correlated with anhedonia score in patients. These results suggest that patients with schizophrenia may have an abnormality in the self-related cortical midline structures and particularly, abnormal ACC activation may be involved in anhedonia. Disrupted self-referential processing may be a possible cause of anhedonia in schizophrenia.

MAM (E17) rodent developmental model of neuropsychiatric disease: disruptions in learning and dysregulation of nucleus accumbens dopamine release, but spared executive function

RATIONALE

Gestational day 17 methylazoxymethanol (MAM) treatment has been shown to reproduce, in rodents, some of the alterations in cortical and mesolimbic circuitries thought to contribute to schizophrenia.

OBJECTIVE

We characterized the behavior of MAM animals in tasks dependent on these circuitries to see what behavioral aspects of schizophrenia the model captures. We then characterized the integrity of mesolimbic dopamine neurotransmission in a subset of animals used in the behavioral experiments.

METHODS

MAM animals' capacity for working memory, attention, and resilience to distraction was tested with two different paradigms. Cue-reward learning and motivation were assayed with Pavlovian conditioned approach. Measurements of electrically stimulated phasic and tonic DA release in the nucleus accumbens with fast-scan cyclic voltammetry were obtained from the same animals used in the Pavlovian task.

RESULTS

MAM animals' basic attentional capacities were intact. MAM animals took longer to acquire the working memory task, but once learned, performed at the same level as shams. MAM animals were also slower to develop a Pavlovian conditioned response, but otherwise no different from controls. These same animals showed alterations in terminal DA release that were unmasked by an amphetamine challenge.

CONCLUSIONS

The predominant behavioral-cognitive feature of the MAM model is a learning impairment that is evident in acquisition of executive function tasks as well as basic Pavlovian associations. MAM animals also have dysregulated terminal DA release, and this may contribute to observed behavioral differences. The MAM model captures some functional impairments of schizophrenia, particularly those related to acquisition of goal-directed behavior.

Investigating the empirical support for therapeutic targets proposed by the temporal experience of pleasure model in schizophrenia: A systematic review

BACKGROUND

Anhedonia and amotivation are substantial predictors of poor functional outcomes in people with schizophrenia and often present a formidable barrier to returning to work or building relationships. The Temporal Experience of Pleasure Model proposes constructs which should be considered therapeutic targets for these symptoms in schizophrenia e.g. anticipatory pleasure, memory, executive functions, motivation and behaviours related to the activity. Recent reviews have highlighted the need for a clear evidence base to drive the development of targeted interventions.

OBJECTIVE

To review systematically the empirical evidence for each TEP model component and propose evidence-based therapeutic targets for anhedonia and amotivation in schizophrenia.

METHOD

Following PRISMA guidelines, PubMed and PsycInfo were searched using the terms "schizophrenia" and "anhedonia". Studies were included if they measured anhedonia and participants had a diagnosis of schizophrenia. The methodology, measures and main findings from each study were extracted and critically summarised for each TEP model construct.

RESULTS

80 independent studies were reviewed and executive functions, emotional memory and the translation of motivation into actions are highlighted as key deficits with a strong evidence base in people with schizophrenia. However, there are many relationships that are unclear because the empirical work is limited by over-general tasks and measures.

CONCLUSIONS

Promising methods for research which have more ecological validity include experience sampling and behavioural tasks assessing motivation. Specific adaptations to Cognitive Remediation Therapy, Cognitive Behavioural Therapy and the utilisation of mobile technology to enhance representations and emotional memory are recommended for future development.