Reward: From Basic Reinforcers to Anticipation of Social Cues

Impaired social reward processing in individuals with Internet gaming disorder and its relationship with early face perception

Previous research has found that individuals with Internet gaming disorder (IGD) show different patterns of social function impairments in game-related and real-life social contexts. Impaired social reward processing may be the underlying mechanism according to the Social Motivation Theory. Thus, in this study, event-related potentials were recorded from 24 individuals with IGD and 24 healthy gamers during a social judgement task. We focused on reward positivity (RewP) elicited by game-related and real-life social rewards, and N170 elicited by game avatar faces and real faces. These indicators were used to explore the neurocognitive mechanism of impaired social reward processing in individuals with IGD and its relationship with early face perception. Results showed that (1) the RewP elicited by real-life social reward was considerably reduced in individuals with IGD relative to healthy gamers. (2) The N170 elicited by game avatar faces in individuals with IGD was larger than that elicited by real faces. However, the N170 was not associated with RewP in either group. (3) The score for IGD severity was correlated with the RewP elicited by real-life social reward and the N170 elicited by game avatar face. In conclusion, the present study suggests that the impaired social reward processing in individuals with IGD is mainly manifested in a decreased neural sensitivity to real-life social reward. Meanwhile, the reduced RewP elicited by real-life social reward and the enhanced N170 elicited by game avatar face might serve as potential biomarkers for IGD.

Balance Between Projecting Neuronal Populations of the Nucleus Accumbens Controls Social Behavior in Mice

BACKGROUND

Deficient social interactions are a hallmark of major neuropsychiatric disorders, and accumulating evidence points to altered social reward and motivation as key underlying mechanisms of these pathologies. In the present study, we further explored the role of the balance of activity between D1 and D2 receptor-expressing striatal projection neurons (D1R- and D2R-SPNs) in the control of social behavior, challenging the hypothesis that excessive D2R-SPN activity, rather than deficient D1R-SPN activity, compromises social behavior.

METHODS

We selectively ablated D1R- and D2R-SPNs using an inducible diphtheria toxin receptor-mediated cell targeting strategy and assessed social behavior as well as repetitive/perseverative behavior, motor function, and anxiety levels. We tested the effects of optogenetic stimulation of D2R-SPNs in the nucleus accumbens (NAc) and pharmacological compounds repressing D2R-SPN.

RESULTS

Targeted deletion of D1R-SPNs in the NAc blunted social behavior in mice, facilitated motor skill learning, and increased anxiety levels. These behaviors were normalized by pharmacological inhibition of D2R-SPN, which also repressed transcription in the efferent nucleus, the ventral pallidum. Ablation of D1R-SPNs in the dorsal striatum had no impact on social behavior but impaired motor skill learning and decreased anxiety levels. Deletion of D2R-SPNs in the NAc produced motor stereotypies but facilitated social behavior and impaired motor skill learning. We mimicked excessive D2R-SPN activity by optically stimulating D2R-SPNs in the NAc and observed a severe deficit in social interaction that was prevented by D2R-SPN pharmacological inhibition.

CONCLUSIONS

Repressing D2R-SPN activity may represent a promising therapeutic strategy to relieve social deficits in neuropsychiatric disorders.

Nucleus accumbens core single cell ensembles bidirectionally respond to experienced versus observed aversive events

Fear learning is a critical feature of survival skills among mammals. In rodents, fear learning manifests itself through direct experience of the aversive event or social transmission of aversive stimuli such as observing and acting on conspecifics' distress. The neuronal network underlying the social transmission of information largely overlaps with the brain regions that mediate behavioral responses to aversive and rewarding stimuli. In this study, we recorded single cell activity patterns of nucleus accumbens (NAc) core neurons using in vivo optical imaging of calcium transients via miniature scopes. This cutting-edge imaging methodology not only allows us to record activity patterns of individual neurons but also lets us longitudinally follow these individual neurons across time and different behavioral states. Using this approach, we identified NAc core single cell ensembles that respond to experienced and/or observed aversive stimuli. Our results showed that experienced and observed aversive stimuli evoke NAc core ensemble activity that is largely positive, with a smaller subset of negative responses. The size of the NAc single cell ensemble response was greater for experienced aversive stimuli compared to observed aversive events. Our results also revealed sex differences in the NAc core single cell ensembles responses to experience aversive stimuli, where females showed a greater accumbal response. Importantly, we found a subpopulation within the NAc core single cell ensembles that show a bidirectional response to experienced aversive stimuli versus observed aversive stimuli (i.e., negative response to experienced and positive response to observed). Our results suggest that the NAc plays a role in differentiating somatosensory experience from social observation of aversion at a single cell level. These results have important implications for psychopathologies where social information processing is maladaptive, such as autism spectrum disorders.

Computational mechanisms underlying motivation to earn symbolic reinforcers

Reinforcement learning (RL) is a theoretical framework that describes how agents learn to select options that maximize rewards and minimize punishments over time. We often make choices, however, to obtain symbolic reinforcers (e.g. money, points) that can later be exchanged for primary reinforcers (e.g. food, drink). Although symbolic reinforcers are motivating, little is understood about the neural or computational mechanisms underlying the motivation to earn them. In the present study, we examined how monkeys learn to make choices that maximize fluid rewards through reinforcement with tokens. The question addressed here is how the value of a state, which is a function of multiple task features (e.g. current number of accumulated tokens, choice options, task epoch, trials since last delivery of primary reinforcer, etc.), drives value and affects motivation. We constructed a Markov decision process model that computes the value of task states given task features to capture the motivational state of the animal. Fixation times, choice reaction times, and abort frequency were all significantly related to values of task states during the tokens task (n=5 monkeys). Furthermore, the model makes predictions for how neural responses could change on a moment-by-moment basis relative to changes in state value. Together, this task and model allow us to capture learning and behavior related to symbolic reinforcement.

Nucleus accumbens core single cell ensembles bidirectionally respond to experienced versus observed aversive events

Empathy is the ability to adopt others' sensory and emotional states and is an evolutionarily conserved trait among mammals. In rodents, empathy manifests itself as social modulation of aversive stimuli such as acknowledging and acting on conspecifics' distress. The neuronal network underlying social transmission of information is known to overlap with the brain regions that mediate behavioral responses to aversive and rewarding stimuli. In this study, we recorded single cell activity patterns of nucleus accumbens (NAc) core neurons using in vivo optical imaging of calcium transients via miniature scopes. This cutting-edge imaging methodology not only allows us to record activity patterns of individual neurons but also lets us longitudinally follow these individual neurons across time and different behavioral states. Using this approach, we identified NAc core single cell ensembles that respond to experienced and/or observed aversive stimuli. Our results showed that experienced and observed aversive stimuli evoke NAc core ensemble activity that is largely positive, with a smaller subset of negative responses. The size of the NAc single cell ensemble response was greater for experienced aversive stimuli compared to observed aversive events. Our results also revealed a subpopulation within the NAc core single cell ensembles that show a bidirectional response to experienced aversive stimuli versus observed aversive stimuli (i.e., negative response to experienced and positive response to observed). These results suggest that the NAc plays a role in differentiating somatosensory experience from social observation of aversion at a single cell level. This has important implications for psychopathologies where social information processing is maladaptive, such as autism spectrum disorders.

All the Pringle ladies: Neural and behavioral responses to high-calorie food rewards in young adult women

Reward processing is vital for learning and survival, and can be indexed using the Reward Positivity (RewP), an event-related potential (ERP) component that is larger for rewards than losses. Prior work suggests that heightened motivation to obtain reward, as well as greater reward value, is associated with an enhanced RewP. However, the extent to which internal and external factors modulate neural responses to rewards, and whether such neural responses motivate reward-seeking behavior, remains unclear. The present study investigated whether the degree to which a reward is salient to an individual's current motivational state modulates the RewP, and whether the RewP predicts motivated behaviors, in a sample of 133 women. To elicit the RewP, participants completed a forced-choice food reward guessing task. Data were also collected on food-related behaviors (i.e., type of food chosen, consumption of the food reward) and motivational salience factors (i.e., self-reported hunger, time since last meal, and subjective "liking" of food reward). Results showed that hungrier participants displayed an enhanced RewP compared to less hungry individuals. Further, self-reported snack liking interacted with RewP magnitude to predict behavior, such that when participants reported low levels of snack liking, those with a smaller RewP were more likely to consume their snacks than those with a larger RewP. Our data suggest that food-related motivational state may increase neural sensitivity to food reward in young women, and that neural markers of reward sensitivity might interact with subjective reward liking to predict real-world eating behavior.

Reward enhances resilience to chronic social defeat stress in mice: Neural ECs and mGluR5 mechanism via neuroprotection in VTA and DRN

INTRODUCTION

Stress often leads to emotional disorders such as depression. The reward might render this effect through the enhancement of stress resilience. However, the effect of reward on stress resilience under different intensities of stress needs more evidence, and its potential neural mechanism has been poorly revealed. It has been reported that the endogenous cannabinoid system (ECs) and downstream metabolic glutamate receptor 5 (mGluR5) are closely related to stress and reward, which might be the potential cerebral mechanism between reward and stress resilience, but there is a lack of direct evidence. This study aims to observe the effect of reward on stress resilience under different intensities of stress and further explore potential cerebral mechanisms underlying this effect.

METHODS

Using the chronic social defeat stress model, we applied reward (accompanied by a female mouse) under different intensities of stress in mice during the modeling process. The impact of reward on stress resilience and the potential cerebral mechanism were observed after modeling through behavioral tests and biomolecules.

RESULTS

The results showed that stronger stress led to higher degrees of depression-like behavior. Reward reduced depression-like behavior and enhanced stress resilience (all p-value <0.05) (more social interaction in the social test, less immobility time in the forced swimming test, etc.), with a stronger effect under the large stress. Furthermore, the mRNA expression levels of CB1 and mGluR5, the protein expression level of mGluR5, and the expression level of 2-AG (2-arachidonoylglycerol) in both ventral tegmental area (VTA) and dorsal raphe nucleus (DRN) were significantly upregulated by reward after modeling (all p-value <0.05). However, the protein expression of CB1 in VTA and DRN and the expression of AEA (anandamide) in VTA did not differ significantly between groups. Intraperitoneal injection of a CB1 agonist (URB-597) during social defeat stress significantly reduced depression-like behavior compared with a CB1 inhibitor (AM251) (all p-value <0.05). Interestingly, in DRN, the expression of AEA in the stress group was lower than that of the control group, with or without reward (all p-value <0.05).

DISCUSSION

These findings demonstrate that combined social and sexual reward has a positive effect on stress resilience during chronic social defeat stress, potentially by influencing the ECs and mGluR5 in VTA and DRN.

Why help others? Insights from rodent to human early childhood research

Helping behavior are actions aiming at assisting another individual in need or to relieve their distress. The occurrence of this behavior not only depends on automated physiological mechanisms, such as imitation or emotional contagion, that is, the individual's emotion and physiological state matching with others, but also needs motivation to sustain. From a comparative and developmental perspective, we discover that the motivation for helping behavior has a deep foundation both phylogenetically and ontogenetically. For example, empathic concern for others, relieving personal distress and the desire for social contact are universal motivations across rodents, non-human primates and human early childhoods. Therefore, a circle-layered model integrating evidences for motivation for helping behavior from rodent to human early childhood research is proposed: the inner circle contains the emotional-behavioral system and the outer circle contains the affective-cognitive system. The application of this model has significance for both behavioral neuroscience research and cultivating prosocial behavior in human society.

Altered hormonal patterns in borderline personality disorder mother-child interactions

BACKGROUND

Oxytocin, cortisol, and testosterone are involved in the processing of reward and stress and greatly influence mother-child interactions. Altered hormonal systems have been associated with borderline personality disorder (BPD), a disorder characterized by interpersonal deficits. Mothers with BPD tend to perceive interactions with the child as less rewarding and more stressful and interactions are often less reciprocal and have more negative states (i.e. constricted, tense, uncoordinated behaviors). Their children are at elevated risk for psychopathologies. Here, we studied underlying hormonal mechanisms of disrupted mother-child interaction in BPD.

METHODS

Twenty-five mothers with BPD and 29 healthy mothers with their 18- to 36-month-old toddlers participated in a free-play mother-child interaction, which was evaluated with the Coding Interactive Behavior (CIB) Manual. Maternal blood samples were analyzed at baseline for oxytocin, cortisol, and testosterone, and after interaction for oxytocin and cortisol.

RESULTS

Oxytocin decreased and cortisol remained unchanged in mothers with BPD while healthy mothers showed stable oxytocin and decreased cortisol after interaction. Testosterone basal levels were significantly higher in mothers with BPD. Cortisol reactivity and testosterone levels mediated the association between maternal BPD and dyadic negative states during interaction.

CONCLUSIONS

These findings suggest that alterations in oxytocin, cortisol, and testosterone contribute to disruptions in mother-child interaction in BPD. Interacting with their child might not result in reward and relief of stress in mothers with BPD in the same way as in healthy mothers. Further research is needed to understand more about dyadic bio-behavioral processes in order to provide targeted parenting support. This could break the cycle of transgenerational transmission and improve maternal and child well-being.

Cannabidiol for the treatment of autism spectrum disorder: hope or hype?

RATIONALE

Autism spectrum disorder (ASD) is defined as a group of neurodevelopmental disorders whose symptoms include impaired communication and social interaction, restricted and repetitive patterns of behavior, and varying levels of intellectual disability. ASD is observed in early childhood and is one of the most severe chronic childhood disorders in prevalence, morbidity, and impact on society. It is usually accompanied by attention deficit hyperactivity disorder, anxiety, depression, sleep disorders, and epilepsy. The treatment of ASD has low efficacy, possibly because it has a heterogeneous nature, and its neurobiological basis is not clearly understood. Drugs such as risperidone and aripiprazole are the only two drugs available that are recognized by the Food and Drug Administration, primarily for treating the behavioral symptoms of this disorder. These drugs have limited efficacy and a high potential for inducing undesirable effects, compromising treatment adherence. Therefore, there is great interest in exploring the endocannabinoid system, which modulates the activity of other neurotransmitters, has actions in social behavior and seems to be altered in patients with ASD. Thus, cannabidiol (CBD) emerges as a possible strategy for treating ASD symptoms since it has relevant pharmacological actions on the endocannabinoid system and shows promising results in studies related to disorders in the central nervous system.

OBJECTIVES

Review the preclinical and clinical data supporting CBD's potential as a treatment for the symptoms and comorbidities associated with ASD, as well as discuss and provide information with the purpose of not trivializing the use of this drug.

Deficiency of the ywhaz gene, involved in neurodevelopmental disorders, alters brain activity and behaviour in zebrafish

Genetic variants in YWHAZ contribute to psychiatric disorders such as autism spectrum disorder and schizophrenia, and have been related to an impaired neurodevelopment in humans and mice. Here, we have used zebrafish to investigate the mechanisms by which YWHAZ contributes to neurodevelopmental disorders. We observed that ywhaz expression was pan-neuronal during developmental stages and restricted to Purkinje cells in the adult cerebellum, cells that are described to be reduced in number and size in autistic patients. We then performed whole-brain imaging in wild-type and ywhaz CRISPR/Cas9 knockout (KO) larvae and found altered neuronal activity and connectivity in the hindbrain. Adult ywhaz KO fish display decreased levels of monoamines in the hindbrain and freeze when exposed to novel stimuli, a phenotype that can be reversed with drugs that target monoamine neurotransmission. These findings suggest an important role for ywhaz in establishing neuronal connectivity during development and modulating both neurotransmission and behaviour in adults.

Benefits of gamification in medical education

Medical education is changing at a fast pace. Students attend medical school with a high degree of technological literacy and a desire for a diverse educational experience. As a result, a growing number of medical schools are incorporating technology-enhanced active learning and multimedia education tools into their curriculum. Gamified training platforms include educational games, mobile medical apps, and virtual patient scenarios. We provide a systematic review of what is meant by gamification in this era. Specific educational games, mobile apps, and virtual simulations that may be used for preclinical and clinical training have been discovered and classified. The available data were presented in terms of the recognized platforms for medical education's possible benefits. Virtual patient simulations have been shown to enhance learning results in general. Gamification could improve learning, engagement, and cooperation by allowing for real-world application. They may also help with promoting risk-free healthcare decision-making, remote learning, learning analytics, and quick feedback. We account for Preclinical training which included 5 electronic games and 4 mobile apps, while clinical training included 5 electronic games, 10 mobile applications, and 12 virtual patient simulation tools. There were additionally nine more gamified virtual environment training products that were not commercially accessible. Many of these studies have shown that utilizing gamified media in medical education may confer advantages. This collection of hyperlinked resources may be utilized by medical students, practitioners, and instructors at all levels.

The causal role of the bilateral ventrolateral prefrontal cortices on emotion regulation of social feedback

The ventrolateral prefrontal cortices (VLPFC) are crucial regions involved in voluntary emotion regulation. However, the lateralization of the VLPFC in downregulating negative emotions remains unclear; and whether the causal role of the VLPFC is generalizable to upregulating positive emotions is unexplored. This study used transcranial magnetic stimulation (TMS) to examine the causal relationship between the left/right VLPFC and social emotion reappraisal. One hundred and twenty participants were randomly assigned to either active (left and right VLPFC groups, n = 40/40) or sham (vertex, n = 40) TMS groups. Participants were instructed to passively receive social feedback or use reappraisal strategies to positively regulate their emotions. While the subjective emotional rating showed that the bilateral VLPFC facilitated the reappraisal success, the electrophysiological measure of the late positive potential (LPP) demonstrated a more critical role of the right VLPFC on social pain relief (decreased LPP amplitudes) and social reward magnification (enhanced LPP amplitudes). In addition, the influence of emotion regulation on social evaluation was found to be mediated by the memory of social feedback, indicating the importance of memory in social behavioral shaping. These findings suggest clinical protocols for the rehabilitation of emotion-regulatory function in patients with affective and social disorders.

Who initiates punishment, who joins punishment? Disentangling types of third-party punishers by neural traits

The act of punishing unfair behavior by unaffected observers (i.e., third‐party punishment) is a crucial factor in the functioning of human societies. In everyday life, we see different types of individuals who punish. While some individuals initiate costly punishment against an unfair person independently of what other observers do (independent punishers), others condition their punishment engagement on the presence of another person who punishes (conditional punishers). Still others do not want to partake in any sort of punishment (nonpunishers). Although these distinct behavioral types have a divergent impact on human society, the sources of heterogeneity are poorly understood. We present novel laboratory evidence on the existence of these three types. We use anatomical brain characteristics in combination with stated motives to characterize these types. Findings revealed that independent punishers have larger gray matter volume in the right temporo‐parietal junction compared to conditional punishers and nonpunishers, an area involved in social cognition. Conditional punishers are characterized by larger gray matter volume in the right dorsolateral prefrontal cortex, a brain area known to be involved in behavioral control and strategic reasoning, compared to independent punishers and nonpunishers. Finally, both independent punishers and nonpunishers are characterized by larger gray matter volume in an area involved in the processing of social and monetary rewards, that is, the bilateral caudate. By using a neural trait approach, we were able to differentiate these three types clearly based on their neural signatures, allowing us to shed light on the underlying psychological mechanisms.

I, robot: depression plays different roles in human-human and human-robot interactions

Socially engaging robots have been increasingly applied to alleviate depressive symptoms and to improve the quality of social life among different populations. Seeing that depression negatively influences social reward processing in everyday interaction, we investigate this influence during simulated interactions with humans or robots. In this study, 35 participants with mild depression and 35 controls (all from nonclinical populations) finished the social incentive delay task with event-related potential recording, in which they received performance feedback from other persons or from a robot. Compared to the controls, the mild depressive symptom (MDS) group represented abnormalities of social reward processing in the human feedback condition: first, the MDS group showed a lower hit rate and a smaller contingent-negative variation (correlated with each other) during reward anticipation; second, depression level modulated both the early phase (indexed by the feedback-related negativity (FRN)) and the late phase (indexed by the P3) of reward consumption. In contrast, the effect of depression was evident only on FRN amplitude in the robot feedback condition. We suggest that compared to human-human interaction, the rewarding properties of human-robot interaction are less likely to be affected by depression. These findings have implications for the utilization of robot-assisted intervention in clinical practice.

The neurochemistry of social reward during development: What have we learned from rodent models?

Social rewards are fundamental to survival and overall health. Several studies suggest that adequate social stimuli during early life are critical for developing appropriate socioemotional and cognitive skills, whereas adverse social experiences negatively affect the proper development of brain and behavior, by increasing the susceptibility to develop neuropsychiatric conditions. Therefore, a better understanding of the neural mechanisms underlying social interactions, and their rewarding components in particular, is an important challenge of current neuroscience research. In this context, preclinical research has a crucial role: Animal models allow to investigate the neurobiological aspects of social reward in order to shed light on possible neurochemical alterations causing aberrant social reward processing in neuropsychiatric diseases, and they allow to test the validity and safety of innovative therapeutic strategies. Here, we discuss preclinical research that has investigated the rewarding properties of two forms of social interaction that occur in different phases of the lifespan of mammals, that is, mother-infant interaction and social interactions with peers, by focusing on the main neurotransmitter systems mediating their rewarding components. Together, the research performed so far helped to elucidate the mechanisms of social reward and its psychobiological components throughout development, thus increasing our understanding of the neurobiological substrates sustaining social functioning in health conditions and social dysfunction in major psychiatric disorders.

The Paraventricular Nucleus of the Thalamus as an Integrating and Relay Node in the Brain Anxiety Network

The brain anxiety network is composed of a number of interconnected cortical regions that detect threats and execute appropriate defensive responses via projections to the shell of the nucleus accumbens (NAcSh), dorsolateral region of the bed nucleus of the stria terminalis (BSTDL) and lateral region of the central nucleus of the amygdala (CeL). The paraventricular nucleus of the thalamus (PVT) is anatomically positioned to integrate threat- and arousal-related signals from cortex and hypothalamus and then relay these signals to neural circuits in the NAcSh, BSTDL, and CeL that mediate defensive responses. This review describes the anatomical connections of the PVT that support the view that the PVT may be a critical node in the brain anxiety network. Experimental findings are reviewed showing that the arousal peptides orexins (hypocretins) act at the PVT to promote avoidance of potential threats especially following exposure of rats to a single episode of footshocks. Recent anatomical and experimental findings are discussed which show that neurons in the PVT provide divergent projections to subcortical regions that mediate defensive behaviors and that the projection to the NAcSh is critical for the enhanced social avoidance displayed in rats exposed to footshocks. A theoretical model is proposed for how the PVT integrates cortical and hypothalamic signals to modulate the behavioral responses associated with anxiety and other challenging situations.

A projection from the paraventricular nucleus of the thalamus to the shell of the nucleus accumbens contributes to footshock stress-induced social avoidance

The paraventricular nucleus of the thalamus (PVT) is an area of the dorsal midline thalamus that contributes to footshock induced anxiety. The PVT sends a dense projection to the shell of the nucleus accumbens (NAcSh) and the present study explored if this projection is involved in the behavioral changes produced by a single exposure of rats to inescapable footshocks. The inhibitory Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) hM4Di was transduced in PVT neurons that project to the NAcSh. Rats were exposed to an episode of moderately intense footshock (1.5 mA × 2 s × 5) and assigned to either high-responder (HR) or low-responder groups (LR) according to their level of fear generalization 24 h later. The effect of chemogenetic inhibition of the PVT-NAcSh projection on anxiety- and fear-like behaviors was assessed at approximately 2 weeks post-footshock. HR showed a higher level of social avoidance compared to non-shocked animals and LR. The elevated level of social avoidance was attenuated in the HR treated with the hM4Di agonist clozapine (0.01 mg/kg, i.p.) or clozapine N-oxide (CNO) administrations in the NAcSh while avoidance of open spaces and contextual fear expression were not affected. Analysis of protein product of the early to immediate gene cfos indicated that these effects were mediated by dynorphin neurons in the NAcSh. This study provides evidence for a role of a projection from the PVT to the NAcSh in stress-induced social avoidance independent of anxiety to non-social stimuli and contextual fear mechanisms.

Potential role of primed microglia during obesity on the mesocorticolimbic circuit in autism spectrum disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental disease which involves functional and structural defects in selective central nervous system (CNS) regions that harm function and individual ability to process and respond to external stimuli. Individuals with ASD spend less time engaging in social interaction compared to non-affected subjects. Studies employing structural and functional magnetic resonance imaging reported morphological and functional abnormalities in the connectivity of the mesocorticolimbic reward pathway between the nucleus accumbens and the ventral tegmental area (VTA) in response to social stimuli, as well as diminished medial prefrontal cortex in response to visual cues, whereas stronger reward system responses for the non-social realm (e.g., video games) than social rewards (e.g., approval), associated with caudate nucleus responsiveness in ASD children. Defects in the mesocorticolimbic reward pathway have been modulated in transgenic murine models using D2 dopamine receptor heterozygous (D2+/-) or dopamine transporter knockout mice, which exhibit sociability deficits and repetitive behaviors observed in ASD phenotypes. Notably, the mesocorticolimbic reward pathway is modulated by systemic and central inflammation, such as primed microglia, which occurs during obesity or maternal overnutrition. Therefore, we propose that a positive energy balance during obesity/maternal overnutrition coordinates a systemic and central inflammatory crosstalk that modulates the dopaminergic neurotransmission in selective brain areas of the mesocorticolimbic reward pathway. Here, we will describe how obesity/maternal overnutrition may prime microglia, causing abnormalities in dopamine neurotransmission of the mesocorticolimbic reward pathway, postulating a possible immune role in the development of ASD.

Grant Report on Social Reward Learning in Schizophrenia †

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 treatment approaches for social cognitive impairments, using cognitive remediation and/or brain stimulation.

Individual variation in the attribution of incentive salience to social cues

Research on the attribution of incentive salience to drug cues has furthered our understanding of drug self-administration in animals and addiction in humans. The influence of social cues on drug-seeking behavior has garnered attention recently, but few studies have investigated how social cues gain incentive-motivational value. In the present study, a Pavlovian conditioned approach (PCA) procedure was used to identify rats that are more (sign-trackers; STs) or less (goal-trackers; GTs) prone to attribute incentive salience to food reward cues. In Experiment 1, a novel procedure employed social ‘peers’ to compare the tendency of STs and GTs to attribute incentive salience to social reward cues as well as form a social-conditioned place preference. In Experiment 2, social behavior of STs and GTs was compared using social interaction and choice tests. Finally, in Experiment 3, levels of plasma oxytocin were measured in STs and GTs seven days after the last PCA training session, because oxytocin is known to modulate the mesolimbic reward system and social behavior. Compared to GTs, STs attributed more incentive salience to social-related cues and exhibited prosocial behaviors (e.g., social-conditioned place preference, increased social interaction, and social novelty-seeking). No group differences were observed in plasma oxytocin levels. Taken together, these experiments demonstrate individual variation in the attribution of incentive salience to both food- and social-related cues, which has important implications for the pathophysiology of addiction.

Love is analogous to money in human brain: Coordinate-based and functional connectivity meta-analyses of social and monetary reward anticipation

Both social and material rewards play a crucial role in daily life and function as strong incentives for various goal-directed behaviors. However, it remains unclear whether the incentive effects of social and material reward are supported by common or distinct neural circuits. Here, we have addressed this issue by quantitatively synthesizing and comparing neural signatures underlying social (21 contrasts, 207 foci, 696 subjects) and monetary (94 contrasts, 1083 foci, 2060 subjects) reward anticipation. We demonstrated that social and monetary reward anticipation engaged a common neural circuit consisting of the ventral tegmental area, ventral striatum, anterior insula, and supplementary motor area, which are intensively connected during both task and resting states. Functional decoding findings indicate that this generic neural pathway mediates positive value, motivational relevance, and action preparation during reward anticipation, which together motivate individuals to prepare well for the response to the upcoming target. Our findings support the common neural currency hypothesis by providing the first meta-analytic evidence to quantitatively show the common involvement of brain regions in both social and material reward anticipation.

Estrogen and oxytocin involvement in social preference in male mice: a study using a novel long-term social preference paradigm with aromatase, estrogen receptor-α and estrogen receptor-β, oxytocin, and oxytocin receptor knockout male mice

Certain aspects of social behavior help animals make adaptive decisions during encounters with other animals. When mice choose to approach another conspecific, the motivation and preference behind the interaction is not well understood. Estrogen and oxytocin are known to influence a wide array of social behaviors, including social motivation and social preference. The present study investigated the effects of estrogen and oxytocin on social preference using aromatase (ArKO), estrogen receptor (ER) α (αERKO), ERβ (βERKO), oxytocin (OTKO), oxytocin receptor (OTRKO) knockout and their respective wild-type (WT) male mice. Mice were presented with gonadally-intact versus castrated male (IC), intact male versus ovariectomized female (IF), or intact male versus empty cage (IE) stimuli sets for 5 days. ArWT showed no preference for either stimuli in IC and IF and intact male preference in IE, but ArKO mice preferred a castrated male or an ovariectomized female, or had no preference for either stimulus in IC, IF and IE stimuli sets, respectively, suggesting reduced intact male preference. α and β WT mice preferred a castrated male, showed no preference, and preferred an intact male in IC, IF and IE, respectively. αERKO mice displayed similar modified social preference patterns as ArKO, whereas the social preference of βERKO mice remained similar to βWT. OTWT preferred a castrated male whereas OTKO, OTRWT and OTRKO mice failed to show any preference in IC and none showed preference for either stimuli in IF. Collectively, these findings suggest that estrogen regulates social preference in male mice and that impaired social preference in oxytocin-deficient mice may be due to severe deficits in social recognition.

Social motivation in schizophrenia: The impact of oxytocin on vigor in the context of social and nonsocial reinforcement

Experiential negative symptoms-including diminished motivation-have a profound impact on functional outcomes in schizophrenia. Animal research suggests that abnormalities in dopaminergic regulation can negatively impact effort exertion, a translational model that has been applied to individuals with schizophrenia. Paradigms that assess effort-based decision making, for example, suggest less likelihood of choosing high effort tasks that are high in probability of success, and this preference varies with negative symptoms and impaired functioning. Although asociality is another well-documented component of experiential negative symptoms, it is unclear whether diminished motivation for monetary reward extends to the social domain. To test this question, the authors designed the Social Vigor Task (SVT)-a measure of effort exertion in the context of live social encouragement. They further examined the effect of oxytocin, a neuropeptide implicated in social behavior, on vigor. Forty-two individuals with schizophrenia and 43 healthy controls completed the SVT twice: once after intranasal administration of saline placebo and again after oxytocin. Both groups showed similar increases in vigor in response to social encouragement, suggesting effort in the social context is spared in schizophrenia. Group differences in the effect of social encouragement on vigor varied by point-based reward rate and trial length. Oxytocin did not increase vigor during social encouragement in either group. Within the schizophrenia group, clinician-rated passive social withdrawal, but not active social avoidance, was negatively associated with vigor. Results suggest that people with schizophrenia show normative levels of effort in the context of social encouragement; low approach motivation, however, relates to lower effort. (PsycINFO Database Record

Neurobiology of male sexual dysfunctions in psychiatric disorders: the cases of depression, anxiety, mania and schizophrenia

While the pathophysiology of several psychiatric disorders has become modestly elucidated in the last decade, comorbid sexual dysfunctions in such patients are frequently left apart from clinical and research interest. We aimed to address the malfunctioning neurocircuitry underlying sexual dysfunctions in depression, anxiety, schizophrenia and mania. We performed a comprehensive literature review, addressing any combination of the topics of "neurobiology"/"neural", "sexual"/"desire"/"arousal"/"orgasm"/"ejaculation" and "depression"/"anxiety"/"schizophrenia"/"mania"/"bipolar". Altered neurotransmitter levels or connectivity in patients are reported in sexual dysfunctions (either desire, arousal, orgasm and ejaculation) and main psychiatric disorders (depression, anxiety, mania and schizophrenia). Neuronal pathways responsible for the occurrence of sexual dysfunctions in psychiatric disorders can be  figured out by overlap  of their acknowledged pathophysiology. However, specific research in that group is scant, so future tailored studies are warranted to elucidate actual mechanisms.

Alterations of brain volumes in women with early life maltreatment and their associations with oxytocin

Early life maltreatment (ELM) is associated with different neurobiological alterations. Lower oxytocin and altered grey matter volumes (GMV) in brain regions associated with the central oxytocin system, such as the hypothalamus, amygdala, and nucleus accumbens, have been reported in women with ELM. However, the association between peripheral oxytocin and brain morphometry in women with ELM has not been studied yet. We therefore collected blood samples from 33 women with and 25 women without ELM, all without current mental disorders to measure and compare oxytocin levels between the two groups. Furthermore, T1-weighted high-resolution structural magnetic resonance brain images of a subsample of these women were collected, analyzed with voxel-based morphometry, compared between the two groups, and correlated with oxytocin levels. There were no differences in oxytocin levels between the groups. However, oxytocin levels were associated with different brain regions in women with ELM compared with control women without ELM: A positive association between GMV in the nucleus accumbens and oxytocin was specific for control women but not for women with ELM. For the hypothalamus, there was a positive association between GMV and oxytocin in control women. However, the same region was negatively associated with oxytocin in women with ELM and it showed larger GMV compared to control women without ELM. For the amygdala, a negative association between GMV and oxytocin was specific for women with ELM. Results are discussed with regard to previous research on endocrine and neurostructural alterations in individuals with ELM.

The indirect assessment of social anhedonia in Chinese adolescents: Preliminary findings

Nearly all self-report measures of anhedonia have been developed for use in adults. Recently we developed an age and developmentally appropriate measure of social/interpersonal pleasure for adolescents (ACIPS-A), whereby lower scores are indicative of social anhedonia. However the scale had not been administered to Eastern samples. The adolescent version of the Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS-A) was administered to a general, community-derived Chinese adolescent sample of 442 students, including 186 males (44%), who ranged in age from 12 to 18 years old. The 20-item Chinese Temporal Experience of Pleasure (TEPS) was also administered to the sample. Exploratory factor analysis revealed that three factors (Casual bonding, Close relationships, and Shared interests) accounted for nearly 69% of the variance. The total ACIPS-A showed excellent internal consistency, with ordinal alpha = 0.94. Scores on the adolescent version of the ACIPS were positively and significantly associated with total scores on the four Chinese TEPS subscales. The ACIPS-A is a sufficiently robust measure to be useful and valid in Chinese samples as well as in Western (i.e. European and U.S.) samples.

Development of Monetary and Social Reward Processes

The current study investigated monetary and social reward processing in children, adolescents and adults with adapted incentive-delay tasks and self-report questionnaires. Both tasks had three levels of reward magnitudes (no, low, and high). Qualified participants received 15 Chinese Yuan and an honor certificate as monetary and social rewards, respectively. The results indicated that both monetary and social rewards effectively speeded up responses for all three age groups as reward magnitude increased in the choice reaction time task. Among adolescents and adults, males exhibited faster responses in high reward than in low reward condition, while females responded equally fast in both conditions. Among children, girls responded faster to high reward than low reward condition. However, boys committed more errors than girls in low and high reward conditions, and they had exhibited more errors in high reward than that in no reward condition for social reward. Regarding the subjective ratings, both children and adolescents reported higher motivation for social reward than for monetary reward. These findings indicated that the males in the adolescent and adult groups were more sensitive to reward than were the females. Moreover, tangible and quantitative social reward had stronger incentive power than monetary reward among children and adolescents.

Inter-trial Coherence of Medial Frontal Theta Oscillations Linked to Differential Feedback Processing in Youth and Young Adults with Autism

BACKGROUND

Impairment in prediction and appreciation for choice outcomes could contribute to several core symptoms of ASD. We examined electroencephalography (EEG) oscillations in 27 youth and young adults diagnosed with autism spectrum disorder (ASD) and 22 IQ-matched neurotypical controls while they performed a chance-based reward prediction task.

METHOD

We re-analyzed our previously published ERP data (Larson et al., 2011) and examined theta band oscillations (4-8 Hz) at frontal midline sites, within a timing window that overlaps with the feedback-related negativity (FRN). We focused on event-related changes after presentation of feedback for reward (WIN) and punitive (LOSE) outcomes, both for spectral power and inter-trial phase coherence.

RESULTS

In our reward prediction task, for both groups, medial frontal theta power and phase coherence were greater following LOSE compared to WIN feedback. However, compared to controls, inter-trial coherence of medial frontal theta was significantly lower overall (across both feedback types) for individuals with ASD. Our results indicate that while individuals with ASD are sensitive to the valence of reward feedback, comparable to their neurotypical peers, they have reduced synchronization of medial frontal theta activity during feedback processing.

CONCLUSIONS

This finding are consistent with previous studies showing neural variability in ASD and suggest that the processes underlying decision-making and reinforcement learning may be atypical and less efficient in ASD.

The case for investigating social context in laboratory studies of smoking

BACKGROUND

With increasing frequency, addiction is conceived of as a brain disease, and such accounts seem especially pertinent with regard to the rapid delivery of nicotine to the brain via cigarette smoke. Moreover, drug administration trials (cigarette puffs) suggest that the behavior of smoking becomes automatized, with individuals developing prototypical approaches to smoking a cigarette. Compared with presumably more social activities, such as drinking alcohol, there may be little opportunity for social processes to influence smoking behavior. However, survey research examining smoking motivation often reveals a broadly defined 'social' factor and field research suggests that social context does influence smoking.

ARGUMENT

We posit that laboratory smoking research has largely ignored social contextual factors that may help to understand better the precise mechanisms underlying smoking behavior and smoking motivation.

METHOD

We reviewed laboratory studies examining the effect of social context (operationalized as modeling) on smoking behavior. Studies were identified by searching PsychInfo and Medline using the following keywords: smoking, nicotine, tobacco, cigarette, consumption, topography, puff, smoking behavior, cigarettes smoked, modeling, imitation, social context, social influence and peer pressure. The reference and citation lists of these studies were then searched to identify additional studies.

CONCLUSIONS

Few laboratory smoking studies target social context. Those few studies indicate that smoking behavior can be influenced by the presence of others. There is also some evidence that social context influences the effects of smoking as well as processes related to self-perception and self-regulation that reinforce smoking and hamper smoking cessation efforts.

The Roles of Dopamine D2 Receptor in the Social Hierarchy of Rodents and Primates

Dopamine (DA) plays significant roles in regulation of social behavior. In social groups of humans and other animals, social hierarchy exists, which is determined by several behavioral characteristics such as aggression and impulsivity as well as social affiliations. In this study, we investigated the effects of pharmacological blockade of DA D2 receptor on social hierarchy of Japanese macaque and mouse social groups. We found acute administration of the D2 antagonist, sulpiride, in socially housed Japanese macaques attenuated social dominance when the drug was given to high social class macaques. A similar attenuation of social dominance was observed in high social class mice with D2 antagonist administration. In contrast, D2 antagonist administration in low social class macaque resulted in more stable social hierarchy of the group, whereas such effect was not observed in mouse social group. These results suggest that D2 receptor signaling may play important roles in establishment and maintenance of social hierarchy in social groups of several species of animals.

Clinical trial of modulatory effects of oxytocin treatment on higher-order social cognition in autism spectrum disorder: a randomized, placebo-controlled, double-blind and crossover trial

BACKGROUND

Autism spectrum disorders are neurodevelopmental conditions with severe impairments in social communication and interaction. Pioneering research suggests that oxytocin can improve motivation, cognition and attention to social cues in patients with autism spectrum disorder. The aim of this clinical trial is to characterize basic mechanisms of action of acute oxytocin treatment on neural levels and to relate these to changes in different levels of socio-affective and -cognitive functioning.

METHODS

This clinical study is a randomized, double-blind, cross-over, placebo-controlled, multicenter functional magnetic resonance imaging study with two arms. A sample of 102 male autism spectrum disorder patients, diagnosed with Infantile Autistic Disorder (F84.0 according to ICD-10), Asperger Syndrome (F84.5 according to ICD-10), or Atypical Autism (F84.1 according to ICD-10) will be recruited and will receive oxytocin and placebo nasal spray on two different days. Autism spectrum disorder patients will be randomized to determine who receives oxytocin on the first and who on the second visit. Healthy control participants will be recruited and case-control matched to the autism spectrum disorder patients. The primary outcome will be neural network activity, measured with functional magnetic resonance imaging while participants perform socio-affective and -cognitive tasks. Behavioral markers such as theory of mind accuracy ratings and response times will be assessed as secondary outcomes in addition to physiological measures such as skin conductance. Trait measures for alexithymia, interpersonal reactivity, and social anxiety will also be evaluated. Additionally, we will analyze the effect of oxytocin receptor gene variants and how these potentially influence the primary and secondary outcome measures. Functional magnetic resonance imaging assessments will take place at two time points which will be scheduled at least two weeks apart to ensure a sufficient wash-out time after oxytocin treatment. The study has been approved by an ethical review board and the competent authority.

DISCUSSION

Revealing the mechanisms of acute oxytocin administration, especially on the socio-affective and -cognitive domains at hand, will be a further step towards novel therapeutic interventions regarding autism.

TRIAL REGISTRATION

German Clinical Trial Register DRKS00010053 . The trial was registered on the 8^th of April 2016.