Teasing apart the anticipatory and consummatory processing of monetary incentives: An event-related potential study of reward dynamics

Depression Remission Over Six Months Characterized by Elevated Target-Locked P300 ERP Component: Prospective Evidence Employing an Affective Visual Oddball Task

Depression is a mental health disorder characterized by dysfunction in cognitive and motivational neural systems. Event-related potential (ERP) research has explored these issues and has found that depression is associated with a reduced P300 ERP component, which likely reflects deficits in processes related to attentional allocation, decision-making, and context updating. However, most of the extant research has employed cross-sectional designs, limiting insight into the temporal precedence between the P300 and depression. Prospective investigations of the P300 and depression association are scarce and would provide further insight into the etiopathology of depression. The present study sought to examine the relationship between baseline P300 amplitude, elicited from an affective visual oddball paradigm, and depression remission after 6 months in a sample of adults (n = 48) suffering from current depressive disorders. Findings indicated that a larger P300 amplitude to target stimuli at baseline was associated with depression remission at the six-month follow-up visit, while no differences were observed for P300 components elicited by the distractor or standard stimuli. The present findings suggest that a reduced P300 amplitude to imperative stimuli may indicate a trait-like neural vulnerability of cognitive and motivational deficits contributing to a greater risk of relapse and a more chronic course of depression. Trial Registration: NCT01941862.

Social reward responsiveness as a moderator of the association between perceived bonding with infants and depressive symptoms in postpartum women

There is a need to identify neurobiological and psychosocial risk processes for postpartum depression (PPD). Previous research links low reward responsiveness with lower reported affiliation or bond to one's infant and PPD symptoms, but the potential moderating role of reward processing in the relationship between bonding with infants and PPD has yet to be examined. The current study (n = 117) used a personally salient social reward task to examine whether neural reward responsiveness moderates the association between bonding difficulties and PPD symptoms. Postpartum women (n = 93) completed the Postpartum Bonding Questionnaire biweekly following childbirth until 8 weeks postpartum, with responses averaged across timepoints. At 8 weeks postpartum, participants completed an electroencephalogram (EEG) Social Incentive Delay task, which included social reward feedback indicating participants would see a personally salient social reward (i.e., cute photo of their infant) and neutral feedback indicating participants would see a neutral image while electroencephalogram data were collected. Participants also self-reported depressive symptoms. A larger social RewP was associated with greater perceived bonding difficulties, and social RewP and self-reported bonding interacted to predict PPD symptoms. The association between bonding difficulties and greater PPD symptoms was statistically significant only for women low in social reward responsiveness. RewP to personally salient infant social reward may be a relevant measure of brain function in the context of maternal perceived bonding and PPD risk.

Hyposensitivity to losses under risk but hypersensitivity to gains under ambiguity during feedback evaluation

Uncertainty is ubiquitous in human life and can be fractioned into risk (known probability distribution) and ambiguity (unknown probability distribution), each with distinct functional correlates. This event-related potential study examined how contextual valence influences the dissociation between risk and ambiguity during feedback evaluation through the lens of neural dynamics. We manipulated contextual valence as a gain versus a loss context. In the gain context, decisions resulted in either gains or nongains, while in the loss context, decisions led to losses or nonlosses. We recorded EEG from 40 participants while they completed a wheel-of-fortune task under conditions of risk and ambiguity in both contexts. We observed a stronger valence effect on the P3a in the loss context under risk, but a stronger valence effect on the P3b in the gain context under ambiguity. Further comparisons revealed that feedback evaluation was primarily driven by a smaller P3a in response to losses under risk, but by a larger P3a and P3b in response to gains under ambiguity. Parametric analyses found that both the reward positivity and P3a for gains and nongains were modulated by winning probability under risk, while the P3a for gains was influenced by ambiguity level under ambiguity. Our findings demonstrate the dissociable influences of contextual valence on feedback-related neural dynamics based on uncertainty type, supporting a critical role of valence-asymmetry in distinguishing risk from ambiguity.

Opening the Pandora box: Neural processing of self-relevant negative social information

Curiosity is a powerful motivator of information-seeking behavior. People seek not only positive, but also aversive social information about others. However, whether people also seek unfavorable social information about themselves, as well as the neural mechanisms that may drive such seemingly counterintuitive behavior remain unclear. To address this gap, we developed a novel electroencephalography-compatible Social Incentive Delay (SID) task, which was implemented in 30 healthy young adults as they responded as fast as possible to a target to receive positive or avoid negative comments about their own or about others' Instagram photos. Reaction times were slower for negative vs positive comments' conditions, but only for participants' own photos, revealing less motivation to avoid negative rather than seek positive self-relevant social feedback. Coherently, receiving negative feedback, as opposed to avoiding it, evoked larger amplitudes in the Reward Positivity (RewP) and FB-P3 time-range, especially for participants' own photos, indicating that receiving a negative comment was more rewarding and more salient than not receiving any comment at all. Our findings challenge prior evidence suggesting that humans instinctively avoid aversive stimuli, and they shed light on the neurophysiological mechanisms that may underlie this counterintuitive behavior.

Therapeutic Efficacy of Reward Circuit‐Targeted Transcranial Magnetic Stimulation (TMS) on Suicidal Ideation in Depressed Patients: A Sham‐Controlled Trial of Two TMS Protocols

Background: Suicide is one of the leading causes of premature death, and dysfunctional reward processing may serve as a potential mechanism. However, effective treatment targeting reward circuits is rarely reported.

Objective: The present study investigated the therapeutic efficacy of two individualized protocols, repetitive transcranial magnetic stimulation (rTMS) and intermittent theta burst stimulation (iTBS), targeting the left dorsolateral prefrontal cortex (lDLPFC)–nucleus accumbens (NAcc) circuit on suicidal ideation among patients with major depressive disorder (MDD).

Methods: Here, 40 healthy controls (HCs) and 70 MDD patients (MDDs) were recruited for this double‐blinded, sham‐controlled clinical trial. The reward learning process during the Iowa gambling task (IGT) was initially measured at the baseline. Further, 62 MDDs were assigned to receive 15 daily sessions of individualized rTMS (n = 25), iTBS (n = 15), or sham treatment (n = 22) to the site of strongest lDLPFC–NAcc connectivity.

Results: We found MDDs demonstrated abnormalities in both IGT performance and reward‐associated event‐related potential (ERP) components compared to HCs. MDDs in the rTMS and iTBS groups showed significant improvements in suicidal ideation and anhedonia symptoms compared to the sham group. The rTMS group also exhibited a more negative‐going N170 and feedback‐related negativity (FRN) after treatment, and the increase in N170 absolute amplitude posttreatment showed a trend of correlation with improved Temporal Experience Pleasure Scales (TEPSs) and TEPS‐anticipatory (TEPS‐ant) scores.

Conclusion: The current study indicates that reward circuit‐based rTMS and iTBS showed comparable antisuicidal effects in depressive patients, suggesting that the lDLPFC–NAcc pathway may serve as a potential treatment target.

Trial Registration: ClinicalTrials.gov identifier: NCT03991572

Blunted neural response to real-life social reward anticipation in internet gaming disorder: An event-related potential study

Recent research indicates that individuals with Internet gaming disorder (IGD) exhibit impaired social reward processing, evidenced by reduced neural sensitivity to real-life social reward. The aim of the present study is to further investigate the impaired processing of social reward anticipation and reward consumption in individuals with IGD, and explore the relationship between these two components. Using a social incentive delay task with game-related and real-life versions, combined with event-related potential (ERP) technology, we examined 25 individuals with IGD and 25 matched healthy game players. The results showed that, at the behavioral level, individuals with IGD showed significantly slower reaction times to real-life target stimuli compared with game-related target stimuli, which is not observed in healthy controls. At the neural level, the Cue-P3 elicited by real-life incentive cues in individuals with IGD was significantly smaller than that elicited by game-related incentive cues. However, these effects were no longer significant after adding depression and anxiety scores as covariates. There was no significant difference in reward positivity (RewP) elicited between the two types of reward consumption. Furthermore, individuals with IGD showed a positive correlation between Cue-P3 elicited by game-related social incentive cue and RewP elicited by game-related social reward. However, this effect was not observed in the healthy controls. In conclusion, the present study suggests that the blunted allocation of motivated neural attention resources to real-life social incentive cues in individuals with IGD may be the key mechanism underlying their impaired social reward processing. This impairment may be influenced by the higher levels of depression and anxiety symptoms commonly observed in individuals with IGD.

Cross-species translational paradigms for assessing positive valence system as defined by the RDoC matrix

Functions associated with processing reward-related information are fundamental drivers of motivation, learning, and goal-directed behavior. Such functions have been classified as the positive valence system under the Research Domain and Criteria (RDoC) criteria and are negatively impacted across a range of psychiatric disorders and mental illnesses. The positive valence system is composed of three comprehensive categories containing related but dissociable functions that are organized into either Reward Responsiveness, Reward Learning, or Reward Valuation. The presence of overlapping behavioral dysfunction across diagnostic mental disorders is in-part what motivated the RDoC initiative, which emphasized that the study of mental illness focus on investigating relevant behavior and cognitive functions and their underlying mechanisms, rather than separating efforts on diagnostic categories (i.e., transdiagnostic). Moreover, the RDoC approach is well-suited for preclinical neuroscience research, as the rise in genetic toolboxes and associated neurotechnologies enables researchers to probe specific cellular targets with high specificity. Thus, there is an opportunity to dissect whether behaviors and cognitive functions are supported by shared or distinct neural mechanisms. For preclinical research to effectively inform our understandings of human behavior however, the cognitive and behavioral paradigms should have predictive, neurobiological, and pharmacological predictive validity to the human test. Touchscreen-based testing systems provide a further advantage for this endeavor enabling tasks to be presented to animals using the same media and task design as in humans. Here, we outline the primary categories of the positive valence system and review the work that has been done cross-species to investigate the neurobiology and neurochemistry underlying reward-related functioning. Additionally, we provide clinical tasks outlined by RDoC, along with validity and/or need for further validation for analogous rodent paradigms with a focus on implementing the touchscreen-based cognitive testing systems.

The effect of performance contingent reward prospects flexibly adapts to more versus less specific task goals

In some situations, for example, when we expect to gain a reward in case of good performance, goal-driven top-down attention is particularly strong. Little is known about the task specificity of such increases of top-down attention due to environmental factors. To understand to what extent performance-contingent reward prospects can result in specific and unspecific changes in cognitive processing, we here investigate reward effects under different levels of task specification. Thirty-two participants performed a visual or an auditory discrimination task cued by two consecutive visual stimuli: First, a reward cue indicated if good performance was rewarded. Second, a task cue announced either which of the two tasks would follow (precise cue) or that both tasks would follow equally likely (imprecise cue). Reward and task cue preciseness both significantly improved performance. Moreover, the response time difference between precisely and imprecisely cued trials was significantly stronger in rewarded than in unrewarded trials. These effects were reflected in event-related potential (ERP) slow wave amplitudes: Reward and preciseness both significantly enhanced the contingent negative variation (CNV) prior to the task stimulus. In an early CNV time interval, both factors also showed an interaction. A negative slow wave prior to the task cue was also significantly enhanced for rewarded trials. This effect correlated with the reward difference in response times. These results indicate that reward prospects trigger task-specific changes in preparatory top-down attention which can flexibly adapt over time and across different task requirements. This highlights that a reward-induced increase of cognitive control can occur on different specificity levels.

Muscarinic receptors mediate motivation via preparatory neural activity in humans

Motivation depends on dopamine, but might be modulated by acetylcholine which influences dopamine release in the striatum, and amplifies motivation in animal studies. A corresponding effect in humans would be important clinically, since anticholinergic drugs are frequently used in Parkinson's disease, a condition that can also disrupt motivation. Reward and dopamine make us more ready to respond, as indexed by reaction times (RT), and move faster, sometimes termed vigour. These effects may be controlled by preparatory processes that can be tracked using electroencephalography (EEG). We measured vigour in a placebo-controlled, double-blinded study of trihexyphenidyl (THP), a muscarinic antagonist, with an incentivised eye movement task and EEG. Participants responded faster and with greater vigour when incentives were high, but THP blunted these motivational effects, suggesting that muscarinic receptors facilitate invigoration by reward. Preparatory EEG build-up (contingent negative variation [CNV]) was strengthened by high incentives and by muscarinic blockade, although THP reduced the incentive effect. The amplitude of preparatory activity predicted both vigour and RT, although over distinct scalp regions; frontal activity predicted vigour, whereas a larger, earlier, central component predicted RT. The incentivisation of RT was partly mediated by the CNV, though vigour was not. Moreover, the CNV mediated the drug's effect on dampening incentives, suggesting that muscarinic receptors underlie the motivational influence on this preparatory activity. Taken together, these findings show that a muscarinic blocker impairs motivated action in healthy people, and that medial frontal preparatory neural activity mediates this for RT.

Neurophysiological characteristics of reward processing in individuals at different levels of gaming

Altered reward processing has been repeatedly reported in Internet gaming disorder (IGD). However, it remains unclear whether these changes are linked to the severity of addictive symptoms or the extent of gaming experience. This study examined the neurophysiological responses regarding reward anticipation and consummation in individuals at different levels of gaming (including 22 casual gamers, 31 regular gamers, and 27 individuals with IGD) through a monetary incentive delay task. Three event-related potential components during reward anticipation-cue-related P300 (Cue-P3), contingent negative variation, and stimulus-preceding negativity (SPN)-and two during reward consummation-feedback-related negativity and feedback-related P300 (FB-P3)-were measured. We found that IGD individuals exhibited greater Cue-P3 but lower SPN amplitude compared to casual gamers, while regular gamers fell between the two without significant differences. Regressions indicated that more extensive gaming experience, rather than the severity of the symptoms, primarily contributed to the increased Cue-P3 in IGD. No group differences were found during reward consummation. Our results highlight disrupted reward anticipation processing in IGD, characterized by increased attention bias toward reward cues (Cue-P3) but diminished cognitive resources for reward anticipation (SPN) and emphasize the role of gaming experience in increased attention bias in IGD.

The ERP Components of Reward Processing Modulated by Status-Related Social Comparison

Background

Although social status is closely related to income distribution, few studies have focused on social comparisons caused by income distribution based on social status.

Purpose

The neural indices of status-related social comparisons were investigated by modifying the classical social comparison task with the incorporation of event-related potentials (ERPs).

Methods

The study employed a total of 29 subjects (15 females), the status scores of whom were initially obtained through the utilization of classical measurements of objective (7 items) and subjective (2 items) socioeconomic status. Subsequently, the subjects were required to complete a dot-estimation task. To induce status-related and response-related (upward, equal, and downward) social comparisons, subjects were informed that rewards were distributed based on whether their status score or their response was superior to that of a selected competitor.

Results

The behavioral results demonstrated that status-related social comparisons were perceived as more unfair than response-related social comparisons. The ERP results indicated that the cue-P3 amplitude was lower under status-related cues than response-related cues. Additionally, the amplitude of feedback-related negativity was larger under status-related equal comparisons than response-related equal comparisons. Furthermore, the P3 amplitude was larger under status-related upward comparisons relative to response-related upward comparisons.

Conclusion

The findings indicated that status-related comparisons may contribute to the development of unfair consideration (enhanced FRN) and a reduction in task motivations (lowered cue-P3). Additionally, the status-related upward comparison may serve as a significant factor in the onset of relative deprivation (enhanced P3). It would therefore be beneficial to gain further insight into the neural basis of social comparisons.

A U-shaped relationship between chronic academic stress and the dynamics of reward processing

Despite the potential link between stress-induced reward dysfunctions and the development of mental problems, limited human research has investigated the specific impacts of chronic stress on the dynamics of reward processing. Here we aimed to investigate the relationship between chronic academic stress and the dynamics of reward processing (i.e., reward anticipation and reward consumption) using event-related potential (ERP) technology. Ninety healthy undergraduates who were preparing for the National Postgraduate Entrance Examination (NPEE) participated in the study and completed a two-door reward task, their chronic stress levels were assessed via the Perceived Stress Scale (PSS). The results showed that a lower magnitude of reward elicited more negative amplitudes of cue-N2 during the anticipatory phase, and reward omission elicited more negative amplitudes of FRN compared to reward delivery especially in high reward conditions during the consummatory phase. More importantly, the PSS score exhibited a U-shaped relationship with cue-N2 amplitudes regardless of reward magnitude during the anticipatory phase; and FRN amplitudes toward reward omission in high reward condition during the consummatory phase. These findings suggest that individuals exposed to either low or high levels of chronic stress, as opposed to moderate stress levels, exhibited a heightened reward anticipation, and an augmented violation of expectations or affective response when faced with relatively more negative outcomes.

Aberrant social reward dynamics in individuals with melancholic major depressive disorder: An ERP study

BACKGROUND

Compared to monetary rewards, depressive symptoms are specifically associated with abnormal social reward processing. In addition, individuals with melancholic depression may exhibit more significant reward-related impairments. However, there is still limited understanding of the specific alterations in social reward processing in individuals with melancholic depression.

METHODS

Forty patients with melancholic major depressive disorder (MDD), forty patients with non-melancholic MDD, and fifty healthy controls participated in the social incentive delay (SID) tasks with event-related potential (ERP) recording. We measured one anticipatory ERP(cue-N2) and two consummatory ERPs (FRN, fb-P3). Furthermore, we examined correlation between FRN and consummatory anhedonia.

RESULTS

Melancholic MDD patients showed less anticipation of social rewards (cue-N2). Concurrently, melancholic individuals demonstrated diminished reception of social rewards, as evidenced by reduced amplitudes of FRN. Notably, the group x condition interaction effect on FRN was significant (F (2, 127) = 4.15, p = 0.018, η2ρ = 0.061). Melancholic MDD patients had similar neural responses to both gain and neutral feedback (blunted reward positivity), whereas non-melancholic MDD patients (t (39) = 3.09, p = 0.004) and healthy participants (t (49) = 5.25, p < 0.001) had smaller FRN amplitudes when receiving gain feedback relative to neutral feedback. In addition, there was a significant correlation between FRN and consummatory anhedonia in MDD patients.

CONCLUSIONS

Our findings indicated that individuals with melancholic MDD exhibit attenuated neural responses to both anticipated and consumed social rewards. This suggests that aberrant processing of social rewards could serve as a potential biomarker for melancholic MDD.

Performing a Motor Action Enhances Social Reward Processing and Modulates the Neural Processing of Predictive Cues

Associative learning affects many areas of human behavior. Recently, we showed that the neural response to monetary reward is enhanced by performing an action, suggesting interactions between neural systems controlling motor behavior and reward processing. Given that many psychiatric disorders are associated with social anhedonia, a key open question is whether such effects generalize to social rewards, and in how far they affect associative learning. We developed a novel task in which participants (n = 66) received social reward feedback and social punishment either by pressing a button or waiting. Predictive cues were linked to feedback valence with 80% accuracy. Using EEG, we measured the neural response to both predictive cues and social feedback. We found enhanced reward positivity for social reward preceded by an action, and an enhanced N2 for cues predicting negative feedback. Cue-locked P3 amplitude was reduced for cues associated with negative feedback in passive trials only, showing a modulation of outcome anticipation by performing a motor action. This was supported by connectivity analyses showing stronger directed theta synchronization, in line with increased top-down modulation of attention, in active compared with passive trials. These findings suggest that actively obtaining social feedback enhances reward sensitivity and modulates outcome anticipation.

Electrophysiological correlates of (mis)judging social information

Social information can be used to optimize decision-making. However, the simultaneous presentation of multiple sources of advice can lead to a distinction bias in judging the validity of the information. While the involvement of event-related potential (ERP) components in social information processing has been studied, how they are modulated by (mis)judging an advisor's information validity remains unknown. In two experiments participants performed a decision-making task with highly accurate or inaccurate cues. Each experiment consisted of an initial, learning, and test phase. During the learning phase, three advice cues were simultaneously presented and the validity of them had to be assessed. The effect of different cue constellations on ERPs was investigated. In the subsequent test phase, the willingness to follow or oppose an advice cue was tested. Results demonstrated the distinction bias with participants over or underestimating the accuracy of the most uncertain cues. The P2 amplitude was significantly increased during cue presentation when advisors were in disagreement as compared to when all were in agreement, regardless of cue validity. Further, a larger P3 amplitude during outcome presentation was found when advisors were in disagreement and increased with more informative cues. As such, the most uncertain cues were related to the smallest P3 amplitude. The findings hint at the possible role of P3 in judging and learning the predictability of social cues. This study provides novel insights into the role of P2 and P3 components during the judgment of social information validity.

Accelerometer-based and self-reported physical activity and sedentary time and their relationships with the P300 in a Go/No-Go task in older adults

Older adults who experience cognitive decline are more likely to have a reduced quality of life. Identifying lifestyle factors that may influence cognitive processing and in turn improve quality of life during older adulthood is an important area of interest. Cognitive function, as measured by the P300 event-related potential (ERP), has been noted to be modified by physical activity; however, no study to date has examined relationships between this neurophysiological measure and physical activity and sedentary time in older adults. Furthermore, there is a gap in understanding as to whether physical activity and sedentary time assessed using self-reported and accelerometer-based methods similarly relate to the P300. This study aimed to assess the P300 during a Go/No-Go task in relation to self-reported and accelerometer-based physical activity and sedentary time in a community sample of 75 older adults. Results indicated that participants engaging in more moderate-to-vigorous physical activity had larger P300 amplitudes across self-reported and accelerometer-based measurements; however, no relationships between sedentary time and P300 amplitude were observed. Notably, accelerometer-based moderate-to-vigorous physical activity explained P300 amplitudes over and above self-reported moderate-to-vigorous physical activity-an effect that remained significant even after accounting for age. Although these results highlight the importance of moderate-to-vigorous physical activity in relation to cognitive function, as measured via the P300 in older adults, a secondary analysis indicated that engaging in lifestyle activity may have similar effects on the P300 as moderate-to-vigorous physical activity. In sum, the present study highlights the role of habitual engagement in physical activity as a possible means for supporting cognitive function during the aging process.

Anticipatory and consummatory neural correlates of monetary and music rewarding stimuli

Most of the literature on the neural bases of human reward and punishment processing has used monetary gains and losses, but less is known about the neurophysiological mechanisms underlying the anticipation and consumption of other types of rewarding stimuli. In the present study, EEG was recorded from 19 participants who completed a modified version of the Monetary Incentive Delay (MID) task. During the task, cues providing information about potential future outcomes were presented to the participants. Then, they had to respond rapidly to a target stimulus to win money or listening to pleasant music, or to avoid losing money or listening to unpleasant music. Results revealed similar responses for monetary and music cues, with increased activity for cues indicating potential gains compared to losses. However, differences emerged in the outcome phase between money and music. Monetary outcomes showed an interaction between the type of the cue and the outcome in the Feedback Related Negativity and Fb-P3 ERPs and increased theta activity increased for negative feedbacks. In contrast, music outcomes showed significant interactions in the Fb-P3 and theta activities. These findings suggest similar neurophysiological mechanisms in processing cues for potential positive or negative outcomes in these two types of stimuli.

Electrophysiological Correlates of Reward Anticipation in Subjects with Schizophrenia: An ERP Microstate Study

The current study aimed to investigate alterations of event-related potentials (ERPs) microstate during reward anticipation in subjects with schizophrenia (SCZ), and their association with hedonic experience and negative symptoms. EEG data were recorded in thirty SCZ and twenty-three healthy controls (HC) during the monetary incentive delay task in which reward, loss and neutral cues were presented. Microstate analysis and standardized low-resolution electromagnetic tomography (sLORETA) were applied to EEG data. Furthermore, analyses correlating a topographic index (the ERPs score), calculated to quantify brain activation in relationship to the microstate maps, and scales assessing hedonic experience and negative symptoms were performed. Alterations in the first (125.0-187.5 ms) and second (261.7-414.1 ms) anticipatory cue-related microstate classes were observed. In SCZ, reward cues were associated to shorter duration and earlier offset of the first microstate class as compared to the neutral condition. In the second microstate class, the area under the curve was smaller for both reward and loss anticipation cues in SCZ as compared to HC. Furthermore, significant correlations between ERPs scores and the anticipation of pleasure scores were detected, while no significant association was found with negative symptoms. sLORETA analysis showed that hypo-activation of the cingulate cortex, insula, orbitofrontal and parietal cortex was detected in SCZ as compared to HC. Abnormalities in ERPs could be traced already during the early stages of reward processing and were associated with the anticipation of pleasure, suggesting that these dysfunctions might impair effective evaluation of incoming pleasant experiences. Negative symptoms and anhedonia are partially independent results.

Reduced reward responsiveness and depression vulnerability: Consideration of social contexts and implications for intervention

Depression is a prevalent, heterogeneous, and debilitating disorder that often emerges in adolescence, and there is a need to better understand vulnerability processes to inform more targeted intervention efforts. Psychophysiological methods, like event-related potentials (ERPs), can offer unique insights into the cognitive and emotional processes underlying depression vulnerability. I review my and others' research examining ERP measures of reward responsiveness in youth depression and present a conceptual model of the development of low reward responsiveness, its role in depression vulnerability, and potential windows for targeted intervention. There is evidence that a blunted reward positivity (RewP) is observable in children at risk for depression, appears to be shaped in part by early social experiences, and predicts later depressive symptoms in combination with other risk factors like stress exposure. Further, a component consistent with RewP is reliably elicited in response to social acceptance feedback in computerized peer interaction tasks and demonstrates unique associations with social contextual factors and depressive symptoms, supporting the utility of developing psychophysiological tasks that may better capture youths' real-world experiences and social risk processes. In addition, I address the translational implications of clinical psychophysiological research and describe a series of studies showing that a reduced RewP predicts greater reductions in depressive symptoms with treatment but is not modifiable by current treatments like cognitive behavioral therapy. Finally, I describe our preliminary efforts to develop a positive emotion-focused intervention for the offspring of depressed mothers, informed by the RewP literature, and describe future directions for translating psychophysiological research to intervention and prevention.

Social power modulates individuals' neural responses to monetary and social rewards

Although previous research has shown that social power modulates individuals' sensitivity to rewards, it is currently unclear whether social power increases or decreases individuals' sensitivity to rewards. This study employed event-related potentials (ERPs) to investigate the effects of social power on individuals' neural responses to monetary and social rewards. Specifically, participants underwent an episodic priming task to manipulate social power (high-power vs. low-power) and then completed monetary and social delayed incentive tasks while their behavioral responses and electroencephalograms (EEG) were recorded. According to ERP analysis, during the anticipatory stage, low-power individuals exhibited a greater cue-P3 amplitude than high-power individuals in both monetary and social tasks. In the consummatory stage, though no impact of social power on the reward positivity (RewP) was found, low-power individuals showed a higher feedback-P3 (FB-P3) amplitude than high-power individuals, regardless of task types (the MID and SID tasks). In conclusion, these results provide evidence that social power might decrease one's sensitivity to monetary and social rewards in both the anticipatory and consummatory stages.

Specific mechanisms underlying executive and emotional apathy: A phenotyping study

Apathy is a behavioral symptom prevalent both in neuropsychiatric pathologies and in the healthy population. However, the knowledge of the cognitive and neural mechanisms underlying apathy is still very limited, even if clinical and fMRI data support the existence of three forms of apathy (executive, emotional, initiative). These forms could be explained by the alteration of specific mechanisms. This present study's aim is to specify the cognitive and neuronal mechanisms of executive and emotional apathy. We used an EEG study conducted on 68 subjects comprising two groups of young people with specific executive or emotional phenotypes of apathy and one group with no apathy. Despite having symptom of apathy, participants were free of any neurological, metabolic, or psychiatric diagnoses and with high education. Two tasks were used: the DPX for cognitive control and the MID for motivation. Our results showed that distinct mechanisms underlie these two forms of apathy, and, for the first time, we specified these mechanisms. A deficit of the proactive control mode, reflected by a reduced probe-N2 amplitude in AY trials, underlies the executive form of apathy (p < .03), whereas liking motivational blunting, highlighted by a reduced LPP amplitude for financial loss, characterizes the emotional form (p < .04). The main limit of the results is that generalizability to the general population may be reduced since the apathetic samples were chosen for having a specific form of apathy. To conclude, better knowledge of these mechanisms informs new, more targeted treatments, both pharmacological and non-pharmacological, necessary for reducing the debilitating consequences of apathy.

Processing abnormalities in monetary outcome evaluations among male individuals with opioid use disorder: evidence from feedback-related negativity

Background: Numerous studies have highlighted the pivotal role of alterations in the monetary reward system in the development and maintenance of substance use disorder (SUD). Although these alterations have been well documented in various forms of SUD, the electrophysiological mechanisms specific to opioid use disorder (OUD) remain underexplored. Understanding these mechanisms is critical for developing targeted interventions and advancing theories of addiction specific to opioid use.Objectives: To explore abnormalities in monetary reward outcome processing in males with OUD. We hypothesized that control individuals would show higher feedback-related negativity (FRN) to losses, unlike those in the OUD group, where FRN to losses and gains would not differ significantly.Methods: Fifty-seven participants (29 male individuals with OUD [heroin] and 28 male controls) were evaluated. A combination of the monetary incentive delay task (MIDT) and event-related potential (ERP) technology was used to investigate electrophysiological differences in monetary reward feedback processing between the OUD and healthy control groups.Results: We observed a significant interaction between group (control vs. OUD) and monetary outcome (loss vs. gain), indicated by p < .05 and η2p = 0.116. Specifically, control participants showed stronger negative FRN to losses than gains (p < .05), unlike the OUD group (p > .05).Conclusion: This study's FRN data indicate that males with OUD show altered processing of monetary rewards, marked by reduced sensitivity to loss. These findings offer electrophysiological insights into why males with OUD may pursue drugs despite potential economic downsides.

Transcranial Direct Current Stimulation Decreases P3 Amplitude and Inherent Delta Activity during a Waiting Impulsivity Paradigm: Crossover Study

The inability to wait for a target before initiating an action (i.e., waiting impulsivity) is one of the main features of addictive behaviors. Current interventions for addiction, such as transcranial Direct Current Stimulation (tDCS), have been suggested to improve this inability. Nonetheless, the effects of tDCS on waiting impulsivity and underlying electrophysiological (EEG) markers are still not clear. Therefore, this study aimed to evaluate the effects of neuromodulation over the right inferior frontal gyrus (rIFG) on the behavior and EEG markers of reward anticipation (i.e., cue and target-P3 and underlying delta/theta power) during a premature responding task. For that, forty healthy subjects participated in two experimental sessions, where they received active and sham tDCS over the rIFG combined with EEG recording during the task. To evaluate transfer effects, participants also performed two control tasks to assess delay discounting and motor inhibition. The active tDCS decreased the cue-P3 and target-P3 amplitudes, as well as delta power during target-P3. While no tDCS effects were found for motor inhibition, active tDCS increased the discounting of future rewards when compared to sham. These findings suggest a tDCS-induced modulation of the P3 component and underlying oscillatory activity during waiting impulsivity and the discounting of future rewards.

Effort discounts reward-based control allocation: A neurodynamic perspective

The amount of cognitive and neural resources allocated to a task is largely determined by the reward we can expect. However, it remains under-appreciated how this reward-expectation-based control allocation is modulated by effort expenditure. The present event-related potential study investigated this issue through the lens of neural dynamics. Thirty-four participants completed an effort-based monetary incentive delay task while their EEG was recorded. Effort demand was manipulated by adding no (low effort) or much (high effort) noise to the target. Behaviorally, participants exhibited reward-related speeding regardless of effort expenditure, as revealed by faster RTs for reward than neutral trials. Our ERP results demonstrated a widespread facilitatory influence of reward expectation on neural dynamics extending from cue evaluation as indexed by the cue-P3, to control preparation as indexed by the contingent negative variation (CNV), and finally to control engagement as indexed by the target-P3. Critically, the neural facilitation was discounted by effort expenditure during both the control-preparation and control-engagement stages instead of the cue-evaluation stage. Overall, this study provides neurodynamic evidence that control allocation is determined by reward and effort via a cost-benefit analysis.

Neurocognitive reward processes measured via event-related potentials are associated with binge-eating disorder diagnosis and ecologically-assessed behavior

Altered reward processing has been implicated in the onset and maintenance of binge-eating disorder (BED). However, it is unclear which precise neurocognitive reward processes may contribute to BED. In the present study, 40 individuals with BED and 40 age-, sex-, and BMI-matched controls completed a reward (incentive delay) task while their neural activity was recorded using electroencephalography (EEG). Individuals with BED also completed a 10-day ecological momentary assessment (EMA) protocol assessing binge-eating behavior in the natural environment. Event-related potential (ERP) analysis of the EEG indicated that individuals with BED had stronger anticipatory (CNV) and outcome-related (RewP) neural reward activity to food and monetary rewards, compared to controls. However, within the BED group, greater frequency of binge eating during the EMA protocol was associated with stronger anticipatory (CNV) but weaker outcome-related (RewP) neural reward activity. These associations within the BED group were unique to food, and not monetary, rewards. Although preliminary, these results suggest that both anticipatory ("wanting") and outcome ("liking") reward processes may be generally amplified in BED. However, they also suggest that among individuals with BED, disorder severity may be associated with increased anticipatory reward processes ("wanting"), but relatively decreased reward-outcome processing ("liking"), of food rewards specifically.

Feedback negativity and feedback-related P3 in individuals at risk for depression: Comparing surface potentials and current source densities

Blunted responses to reward feedback have been linked to major depressive disorder (MDD) and depression risk. Using a monetary incentive delay task (win, loss, break-even), we investigated the impact of family risk for depression and lifetime history of MDD and anxiety disorder with 72-channel electroencephalograms (EEG) recorded from 29 high-risk and 32 low-risk individuals (15-58 years, 30 male). Linked-mastoid surface potentials (ERPs) and their corresponding reference-free current source densities (CSDs) were quantified by temporal principal components analysis (PCA). Each PCA solution revealed a midfrontal feedback negativity (FN; peak around 310 ms) and a posterior feedback-P3 (fb-P3; 380 ms) as two distinct reward processing stages. Unbiased permutation tests and multilevel modeling of component scores revealed greater FN to loss than win and neutral for all stratification groups, confirming FN sensitivity to valence. Likewise, all groups had greater fb-P3 to win and loss than neutral, confirming that fb-P3 indexes motivational salience and allocation of attention. By contrast, group effects were subtle, dependent on data transformation (ERP, CSD), and did not confirm reduced FN or fb-P3 for at-risk individuals. Instead, CSD-based fb-P3 was overall reduced in individuals with than without MDD history, whereas ERP-based fb-P3 was greater for high-risk individuals than for low-risk individuals for monetary, but not neutral outcomes. While the present findings do not support blunted reward processing in depression and depression risk, our side-by-side comparison underscores how the EEG reference choice affects the characterization of subtle group differences, strongly advocating the use of reference-free techniques.

Lack of effect of methamphetamine on reward-related brain activity in healthy adults

INTRODUCTION

Stimulant drugs are thought to alter processing of rewarding stimuli. However, the mechanisms by which they do this are not fully understood.

METHOD

In this study we used EEG to assess effects of single doses of methamphetamine (MA) on neural responses during anticipation and receipt of reward in healthy volunteers. Healthy young men and women (N = 28) completed three sessions in which they received placebo, a low MA dose (10 mg) or a higher MA dose (20 mg) under double blind conditions. Subjective and cardiovascular measures were obtained, and EEG was used to assess brain activity during an electrophysiological version of the Monetary Incentive Delay (eMID) task.

RESULTS

EEG measures showed expected patterns during anticipation and receipt of reward, and MA produced its expected effects on mood and cardiovascular function. However, MA did not affect EEG responses during either anticipation or receipt of rewards.

CONCLUSIONS

These findings suggest that the effects of MA on EEG signals of reward processing are subtle, and not related to the drug's effects on subjective feelings of well-being. The findings contribute to our understanding of the neural effects of MA during behaviors related to reward.

Comparing monetary gain and loss in the monetary incentive delay task: EEG evidence

What is more effective to guide behavior: The desire to gain or the fear to lose? Electroencephalography (EEG) studies have yielded inconsistent answers. In a systematic exploration of the valence and magnitude parameters in monetary gain and loss processing, we used time-domain and time-frequency-domain analyses to uncover the underlying neural processes. A group of 24 participants performed a monetary incentive delay (MID) task in which cue-induced anticipation of a high or low magnitude of gain or loss was manipulated trial-wise. Behaviorally, the anticipation of both gain and loss expedited responses, with gain anticipation producing greater facilitation than loss anticipation. Analyses of cue-locked P2 and P3 components revealed the significant valence main effect and valence × magnitude interaction: amplitude differences between high and low incentive magnitudes were larger with gain vs. loss cues. However, the contingent negative variation component was sensitive to incentive magnitude but did not vary with incentive valence. In the feedback phase, the RewP component exhibited reversed patterns for gain and loss trials. Time-frequency analyses revealed a large increase in delta/theta-ERS oscillatory activity in high- vs. low-magnitude conditions and a large decrease of alpha-ERD oscillatory activity in gain vs. loss conditions in the anticipation stage. In the consumption stage, delta/theta-ERS turned out stronger for negative than positive feedback, especially in the gain condition. Overall, our study provides new evidence for the neural oscillatory features of monetary gain and loss processing in the MID task, suggesting that participants invested more attention under gain and high-magnitude conditions vs. loss and low-magnitude conditions.

Acute stress selectively blunts reward anticipation but not consumption: An ERP study

Stress-induced dysfunction of reward processing is documented to be a critical factor associated with mental illness. Although many studies have attempted to clarify the relationship between stress and reward, few studies have investigated the effect of acute stress on the temporal dynamics of reward processing. The present study applied event-related potentials (ERP) to examine how acute stress differently influences reward anticipation and consumption. In this study, seventy-eight undergraduates completed a two-door reward task following a Trier Social Stress Task (TSST) or a placebo task. The TSST group showed higher cortisol levels, perceived stress, anxiety, and negative affect than the control group. For the control group, a higher magnitude of reward elicited a reduced cue-N2 but increased stimulus-preceding negativity (SPN), suggesting that controls were sensitive to reward magnitude. In contrast, these effects were absent in the stress group, suggesting that acute stress reduces sensitivity to reward magnitude during the anticipatory phase. However, the reward positivity (RewP) and P3 of both groups showed similar patterns, which suggests that acute stress has no impact on reward responsiveness during the consummatory phase. These findings suggest that acute stress selectively blunts sensitivity to reward magnitude during the anticipatory rather than the consummatory phase.

Relationship between reward-related brain activity and opportunities to sit

The present study tested whether energy-minimizing behaviors evoke reward-related brain activity that promotes the repetition of these behaviors via reinforcement learning processes. Fifty-eight healthy young adults in a standing position performed a task where they could earn a reward either by sitting down or squatting while undergoing electroencephalographic (EEG) recording. Reward-prediction errors were quantified as the amplitude of the EEG-derived reward positivity. Results showed that reward positivity was larger on reward versus no reward trials, confirming the validity of our paradigm to measure evoked reward-related brain activity. However, results showed no evidence that sitting (versus standing and squatting) trials led to larger reward positivity. Moreover, we found no evidence suggesting that this effect was moderated by typical physical activity, physical activity on the day of the study, or energy expenditure during the experiment. However, at the behavioral level, results showed that the probability of choosing the stimulus more likely to lead to sitting than standing increased as the number of trials increased. In addition, results revealed that the probability of changing the selected stimulus was higher when the previous trial was a stand trial relative to a sit trial. In sum, neural results showed no evidence supporting the theory that opportunities to minimize energy expenditure are rewarding. However, behavioral findings suggested participants tend to choose the less effortful behavioral alternative and were therefore consistent with the theory of effort minimization (TEMPA).

Aberrant reward dynamics in depression with anticipatory anhedonia

OBJECTIVE

Previous studies have shown that anticipatory anhedonia is linked to abnormal reward processing. The present study aimed to explore the underlying neural mechanism of the influence of anticipatory anhedonia symptoms on reward processing.

METHODS

Electrophysiological activities in the anticipatory and consummatory phase were recorded during the Monetary Incentive Delay (MID) task in 24 depressed high anticipatory anhedonia (HAA) patients, 25 depressed low anticipatory anhedonia (LAA) patients, and 29 healthy controls (HC).

RESULTS

We suggested a significant condition × group interaction effect on feedback-related negativity (FRN) amplitudes during the consummatory phase, a smaller FRN in reward cue trails compared with neutral cue trail was revealed in the HC and LAA group, but such reward-related effect was not found in the HAA group. In addition, we found significant correlations between FRN, fb-P3 and cue-N1, cue-N2 in the HC group, besides, significant correlations between FRN, fb-P3 and cue-P2 was also revealed in the HC and LAA group. However, no significant correlation was found in HAA patients.

CONCLUSIONS

Our results suggest that the link between the anticipatory and consummatory phase was interrupted in depressed HAA patients, which may be driven by the aberrant consummatory reward processing.

SIGNIFICANCE

The current study is the first one to demonstrate the influence of anticipatory anhedonia symptom on the association between anticipatory and consummatory phase of reward process.

Motivation moderates gender differences in navigation performance

Gender differences in navigation performance are a recurrent and controversial topic. Previous research suggests that men outperform women in navigation tasks and that men and women exhibit different navigation strategies. Here, we investigate whether motivation to complete the task moderates the relationship between navigation performance and gender. Participants learned the locations of landmarks in a novel virtual city. During learning, participants could trigger a top-down map that depicted their current position and the locations of the landmarks. During testing, participants were divided into control and treatment groups and were not allowed to consult the map. All participants were given 16 minutes to navigate to the landmarks, but those in the treatment group were monetarily penalized for every second they spent completing the task. Results revealed a negative relationship between physiological arousal and the time required to locate the landmarks. In addition, gender differences in strategy were found during learning, with women spending more time with the map and taking 40% longer than men to locate the landmarks. Interestingly, an interaction between gender and treatment group revealed that women in the control group required more time than men and women in the treatment group to retrieve the landmarks. During testing, women in the control group also took more circuitous routes compared to men in the control group and women in the treatment group. These results suggest that a concurrent and relevant stressor can motivate women to perform similarly to men, helping to diminish pervasive gender differences found in the navigation literature.

Medial prefrontal transcranial alternating current stimulation for apathy in Huntington's disease

We investigated the effects of transcranial alternating current stimulation (tACS) targeted to the bilateral medial prefrontal cortex (mPFC) and administered at either delta or alpha frequencies, on brain activity and apathy in people with Huntington's disease (HD) (n = 17). Given the novelty of the protocol, neurotypical controls (n = 20) were also recruited. All participants underwent three 20-min sessions of tACS; one session at alpha frequency (Individualised Alpha Frequency (IAF), or 10 Hz when an IAF was not detected); one session at delta frequency (2 Hz); and a session of sham tACS. Participants completed the Monetary Incentive Delay (MID) task with simultaneous recording of EEG immediately before and after each tACS condition. The MID task presents participants with cues signalling potential monetary gains or losses that increase activity in key regions of the cortico-basal ganglia-thalamocortical networks, with dysfunction of the latter network being implicated in the pathophysiology of apathy. We used the P300 and Contingent Negative Variation (CNV) event-related potentials elicited during the MID task as markers of mPFC engagement. HD participants' CNV amplitude significantly increased in response to alpha-tACS, but not delta-tACS or sham. Neurotypical controls' P300 and CNV were not modulated by any of the tACS conditions, but they did demonstrate a significant decrease in post-target response times following alpha-tACS. We present this as preliminary evidence of the ability of alpha-tACS to modulate brain activity associated with apathy in HD.

Be Careful When Using Peer-Influence on Nudging Solicitation: Evidence of Potential Negative Effect from a Sample of Chinese University Students

PURPOSE

Peer information is now commonly used in solicitation. However, scholars have long focused on testing its effectiveness on increasing the donation amount without paying attention to its potential negative effects on donors. Thus, the current study employs high vs low peer donation amount (HPDA vs LPDA) information to explore its effect on "how-much-to-donate" decisions and the corresponding neural and psychological reactions at the same time.

PARTICIPANTS AND METHODS

Student samples from a Chinese university and behavioral experiments with the event-related potential (ERP) method were used in this study.

RESULTS

The behavioral results are consistent with previous research in which HPDA was positively associated with higher donation levels. ERP results show the mechanisms behind decision-making can be summarized into a cognitive approach represented by cost-benefit analysis and an affective approach represented by reward perception. More surprisingly, in contrast to the behavioral results, LPDA elicits higher level of reward perception than HPDA.

CONCLUSION

The results indicate that although HPDA leads to higher levels of donation, donors do not show higher levels of reward anticipation at the neurological level, indicating the increment of donation may come at the cost of donors. Theoretical and practical implications are also discussed.

Reward processing in adolescents with social phobia and depression

OBJECTIVE

Impaired reward processing has been found in individuals with anxiety, but also major depressive disorder (MDD). Here, we studied neural correlates of reward anticipation and processing in a sample of youth with severe social phobia and comorbid depression (SP/MDD) and investigated the specific contribution of SP and MDD symptoms.

METHODS

15 affected, unmedicated and 25 typically developing (TD) youth completed a monetary gambling task, which included a positive, negative and ambiguous reward condition. Event-related potentials representing cue processing (cue P300), reward anticipation (stimulus preceding negativity, SPN), reward sensitivity (feedback related negativity, FRN) and reward processing (reward P300) were analysed.

RESULTS

Reduced amplitudes of the right hemispheric (r)SPN and reward P300 were observed in SP/MDD compared to TD. Within the SP/MDD group SP symptoms correlated with larger rSPN, and FRN amplitudes. MDD symptoms correlated with smaller rSPN and smaller FRN positive-negative difference wave.

CONCLUSIONS

Reward anticipation and feedback processing are reduced in SP/MDD. Higher SP symptoms are associated with stronger neural activation during reward anticipation and reward sensitivity. Depressive symptoms are associated with decreased reward anticipation and sensitivity. Findings are in line with the theory of heightened vigilance in anxiety and blunted reward processing due to anhedonia in MDD.

SIGNIFICANCE

The study results can inform behavioural interventions for SP and MDD.

Distinct neural dynamics underlying risk and ambiguity during valued-based decision making

Uncertainty can be fractioned into risk and ambiguity psychologically and neurobiologically. However, whether and how risk and ambiguity are dissociated in terms of neural dynamics during value-based decision making remain elusive. The present event-related potential (ERP) study addressed these issues by asking participants to perform a wheel-of-fortune task either during a risky context (Experiment 1; N = 30) where outcome probability was known or during an ambiguous context (Experiment 2; N = 30) where outcome probability was unknown. Results revealed that the cue-P3 was more enhanced for risk versus ambiguity during the anticipatory phase, whereas the RewP was more increased for ambiguity than risk during the consummatory phase. Moreover, the SPN and the fb-P3 components were further modulated by the levels of risk and ambiguity, respectively. These findings demonstrate a neural dissociation between risk and ambiguity, which unfolds from the anticipatory phase to the consummatory phase.

Neural deficits in anticipatory and consummatory reward processing are uniquely associated with current depressive symptoms during adolescence

Deficits within the consummatory phase of reward processing are associated with increased depression symptoms and risk; however, few studies have also examined other aspects of reward processing in relation to depression. In the current study, a community sample of 121 adolescents (M_age  = 13.1, Min = 11.14; Max = 15.12; 54% male) completed self-report questionnaires to assess depressive symptoms and the monetary incentive delay (MID) task while EEG was recorded. Results indicated that a reduced cue-P300 as well as a reduced reward positivity (RewP) and feedback negativity (FN) to gain and loss feedback, respectively, were associated with increased depressive symptoms; on the other hand, SPN and feedback P300 were unrelated to depressive symptoms. An exploratory multiple regression analysis revealed that a reduced money cue-P300, a reduced RewP, and a reduced (i.e., less negative) FN, all explained unique variance in depressive symptoms. The current study demonstrates that reduced cue-P300, RewP, and FN amplitudes may reflect distinct deficits in reward processing among adolescents with increased depressive symptoms. Notably, this study is one of the first to leverage the MID task in adolescents in relation to depressive symptoms, allowing for a more in-depth view of the individual differences in reward processing among adolescents with increased depressive symptomatology.

Cognitive-affective processes and suicidality in response to repetitive transcranial magnetic stimulation for treatment resistant depression

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) can elicit 45-55 % response rates and may alleviate suicidality symptoms in treatment resistant depression (TRD). Blunted anticipatory reward sensitivity and negatively biased self-referential processing may predict trajectories of depressive and suicidality symptoms in rTMS for TRD and be modulated during treatment.

METHODS

Fifty-five individuals with TRD received four weeks of low-frequency rTMS applied to the right dorsolateral prefrontal cortex (LFR-rTMS) and were followed until 17 weeks post-baseline. Participants completed behavioral measures of anticipatory reward sensitivity and self-referential processing at baseline and five weeks post-baseline (approximately one-week post-treatment). We examined whether baseline anticipatory reward sensitivity and self-referential processing predicted trajectories of depressive and suicidality symptoms from baseline to follow-up and whether these cognitive-affective variables showed change from baseline to week five.

RESULTS

Anticipatory reward sensitivity and negative self-referential encoding at baseline were associated with higher overall depressive symptoms and suicidality from baseline to 17 weeks post-baseline. At week five, participants self-attributed a higher number of positive traits and a lower number of negative traits and had a lesser tendency to remember negative relative to positive traits they had self-attributed, compared to baseline.

LIMITATIONS

The specificity of these results to LFR-rTMS is unknown in the absence of a comparison group, and our relatively small sample size precluded the interpretation of null results.

CONCLUSIONS

Baseline blunted anticipatory reward sensitivity and negative biases in self-referential processing may be risk factors for higher depressive symptoms and suicidality during and after LFR-rTMS, and LFR-rTMS may modulate self-referential processing.

Low doses of lysergic acid diethylamide (LSD) increase reward-related brain activity

Renewed interest in classic psychedelics as treatments for psychiatric disorders warrants a deeper understanding of their neural mechanisms. Single, high doses of psychedelic drugs have shown promise in treating depressive disorders, perhaps by reversing deficits in reward processing in the brain. In addition, there are anecdotal reports that repeated ingestion of low doses of LSD, or "microdosing", improve mood, cognition, and feelings of wellbeing. However, the effects of low doses of classic psychedelics on reward processing have not been studied. The current study examined the effects of two single, low doses of LSD compared to placebo on measures of reward processing. Eighteen healthy adults completed three sessions in which they received placebo (LSD-0), 13 μg LSD (LSD-13) and 26 μg LSD (LSD-26) in a within-subject, double-blind design. Neural activity was recorded while participants completed the electrophysiological monetary incentive delay task. Event-related potentials were measured during feedback processing (Reward-Positivity: RewP, Feedback-P3: FB-P3, and Late-Positive Potential: LPP). Compared to placebo, LSD-13 increased RewP and LPP amplitudes for reward (vs. neutral) feedback, and LSD-13 and LSD-26 increased FB-P3 amplitudes for positive (vs. negative) feedback. These effects were unassociated with most subjective measures of drug effects. Thus, single, low doses of LSD (vs. placebo) increased three reward-related ERP components reflecting increased hedonic (RewP), motivational (FB-P3), and affective processing of feedback (LPP). These results constitute the first evidence that low doses of LSD increase reward-related brain activity in humans. These findings may have important implications for the treatment of depressive disorders.

Motivationally salient cue processing measured using the monetary incentive delay (MID) task with electroencephalography (EEG): A potential marker of apathy in Huntington's disease

We explored the utility of the Monetary Incentive Delay (MID) task with concurrent encephalography (EEG) as a marker of apathy in people with Huntington's disease (HD) as well as neurotypical controls. Specifically, we assessed between and within-group differences in the amplitude of the P300 and Contingent Negative Variation (CNV) event-related potentials as a function of motivational salience. In contrast to neurotypical controls, HD participants' ERP amplitudes were not differentially modulated by motivationally salient cues (i.e., signalling potential 'gain' or 'loss') compared to 'neutral' cues. Difference waves isolating amplitude specific to the motivationally salient cues were calculated for the P300 and CNV. Only the difference waves for ERPs elicited by 'gain' cues differentiated the groups. The CNV difference wave was also significantly correlated with clinical measures of apathy and processing speed in the HD group. These findings provide initial support for the use of the MID with EEG as a marker of apathy in HD, and its potential as a sensitive outcome measure for novel treatment development.

Δ9-THC reduces reward-related brain activity in healthy adults

RATIONALE

Greater availability of cannabis in the USA has raised concerns about adverse effects of the drug, including possible amotivational states. Lack of motivation may be assessed by examining acute effects of cannabinoids on reward processing.

OBJECTIVES

This study examined single doses of delta-9-tetrahydrocannabinol (∆9-THC; 7.5, 15 mg oral) in healthy adults using a version of the monetary incentive delay (MID) task adapted for electroencephalography (EEG; e-MID) in a within-subjects, double blind design.

METHODS

Two phases of reward processing were examined: anticipation, which occurs with presentation of cues that indicate upcoming reward, punishment, or neutral conditions, and outcome, which occurs with feedback indicating hits or misses. During anticipation, we measured two event-related potential (ERP) components: the P300, which measures attention and motivation, and the LPP, which measures affective processing. During outcome processing, we measured P300 and LPP, as well as the RewP, which measures outcome evaluation.

RESULTS

We found that ∆9-THC modulated outcome processing, but not reward anticipation. Specifically, both doses of ∆9-THC (7.5 and 15 mg) reduced RewP amplitudes after outcome feedback (hits and misses) relative to placebo. ∆9-THC (15 mg) also reduced P300 and LPP amplitudes following hits compared to misses, relative to both placebo and 7.5 mg ∆9-THC.

CONCLUSIONS

These findings suggest that ∆9-THC dampens responses to both reward and loss feedback, which may reflect an "amotivational" state. Future studies are needed to determine generalizability of this effect, such as its pharmacological specificity and its specificity to monetary vs other types of reward.

Expectations of immediate and delayed reward differentially affect cognitive task performance

The current study used a modified Monetary Incentive Delay task to examine the neural mechanisms underlying anticipating and receiving an immediate or delayed reward and examined the influence of pursuing these rewards on cognitive task performance. A pre-cue indicating the potential of gaining a monetary reward (immediate-, delayed-, vs. no-reward) was followed by a target stimulus requiring a fast and accurate response. Then, response-contingent feedback was presented indicating whether or not the participant would receive the corresponding reward. Linear mixed-effect models revealed the fastest behavioural responses and the strongest neural activity, as reflected in event-related-potentials and event-related-spectral-perturbation responses, for immediate reward, followed by delayed reward, with the slowest behavioural responses and the weakest neural activities observed in the no-reward condition. Expectations related to the cue-P3 component and the cue-delta activities predicted behavioural performance, especially in the immediate reward condition. Moreover, exploratory analyses revealed that depression moderated the relationship between target-locked neural activity and behavioural performance in the delayed reward condition, with lower neural activity being related to worse behavioural performance amongst participants scoring high on depression. These results indicate that differential value representations formed through delay discounting directly affect neural responses in reward processing and directly influence the effort invested in the current task, which is reflected by behavioural responses and is in agreement with the expected value of control theory.

An EEG study on the effect of being overweight on anticipatory and consummatory reward in response to pleasant taste stimuli

Two-thirds of adults in the United Kingdom currently suffer from overweight or obesity, making it one of the biggest contributors to health problems. Within the framework of the incentive sensitisation theory, it has been hypothesised that overweight people experience heightened reward anticipation when encountering cues that signal food, such as pictures and smells of food, but that they experience less reward from consuming food compared to normal-weight people. There is, however, little evidence for this prediction. Few studies test both anticipation and consumption in the same study, and even fewer with electroencephalography (EEG). This study sought to address this gap in the literature by measuring scalp activity when overweight and normal-weight people encountered cues signalling the imminent arrival of pleasant and neutral taste stimuli, and when they received these stimuli. The behavioural data showed that there was a smaller difference in valence ratings between the pleasant and neutral taste in the overweight than normal-weight group, in accordance with our hypothesis. However, contrary to our hypothesis, the groups did not differ in their electrophysiological response to taste stimuli. Instead, there was a reduction in N1 amplitude to both taste and picture cues in overweight relative to normal-weight participants. This suggests that reduced attention to cues may be a crucial factor in risk of overweight.

Reduced neural activity when anticipating social versus nonsocial rewards in schizophrenia: Preliminary evidence from an ERP study

Diminished social motivation is a core feature of schizophrenia that might reflect disturbances in social reward processing. It is not known whether these disturbances reflect anticipatory ("wanting") and/or consummatory ("liking") pleasure deficits. The primary aim of this study was to examine social versus nonsocial reward processing during these temporally distinct substages using event-related potential (ERP) components. Twenty-three schizophrenia participants and 20 healthy participants completed an incentive delay task with social (i.e., smiling expressions) and nonsocial (i.e., money) rewards. We measured two anticipatory ERPs (i.e., "wanting") (target anticipation: Contingent Negative Variation [CNV]; feedback anticipation: Stimulus Preceding Negativity [SPN]) and one consummatory ERP (i.e., "liking") (feedback receipt: P300). As a secondary aim, we examined correlations between the ERPs and interview-rated motivational negative symptoms and social functioning. Schizophrenia participants showed overall less target anticipation (blunted CNV) across all trials (social and nonsocial) than healthy participants. Importantly, schizophrenia participants exhibited less anticipation of social rewards relative to nonsocial rewards (SPN), whereas healthy participants showed similar anticipation for both reward types. Both groups showed similar responses to social and nonsocial reward receipt (P300). Furthermore, social reward anticipation during the incentive delay task was associated with more social approach behaviors in the real-world. Together, these findings provide preliminary evidence for intact social reward "liking" and impaired "wanting" in schizophrenia.

Differentiating the abnormalities of social and monetary reward processing associated with depressive symptoms

BACKGROUND

Reward dysfunction is a major dimension of depressive symptomatology, but it remains obscure if that dysfunction varies across different reward types. In this study, we focus on the abnormalities in anticipatory/consummatory processing of monetary and social reward associated with depressive symptoms.

METHODS

Forty participants with depressive symptoms and forty normal controls completed the monetary incentive delay (MID) and social incentive delay (SID) tasks with event-related potential (ERP) recording.

RESULTS

In the SID but not the MID task, both the behavioral hit rate and the ERP component contingent negative variation (CNV; indicating reward anticipation) were sensitive to the interaction between the grouping factor and reward magnitude; that is, the depressive group showed a lower hit rate and a smaller CNV to large-magnitude (but not small-magnitude) social reward cues compared to the control group. Further, these two indexes were correlated with each other. Meanwhile, the ERP components feedback-related negativity and P3 (indicating reward consumption) were sensitive to the main effect of depression across the MID and SID tasks, though this effect was more prominent in the SID task.

CONCLUSIONS

Overall, we suggest that depressive symptoms are associated with deficits in both the reward anticipation and reward consumption stages, particularly for social rewards. These findings have a potential to characterize the profile of functional impairment that comprises and maintains depression.

The Neural and Psychological Processes of Peer-Influenced Online Donation Decision: An Event-Related Potential Study

With the rapid development of information and communication technology (ICT), social media-based donation platforms emerged.¹ These platforms innovatively demonstrate peer information (e.g., number of donated peers) on the donation page, which inevitably brings the peer influence into donors’ donation decision process. However, how the peer influence will affect the psychological process of donation decisions are remained unknown. This study used the number of donated peers to examine the effects of peer influence on donors’ donation decisions and extracted event-related potential (ERP) from electroencephalographic data to explore the underlying psychological process. The behavioral results indicated that the number of donated peers positively influenced donors’ willingness to donate. The ERP results suggested that a larger number of donated peers might indicate a higher level of conformity and greater perceived emotional rewards, as a larger P2 amplitude was observed. Following the early processing of emotional stimuli, cognitive detection of decisional risk took place, and the donors reckoned a smaller number of donated peers as a high potential risk, which was reflected by a larger N2 amplitude. In the later stage, the larger number of donated peers, which represented a higher magnitude of prospective emotional rewards, led to a higher incentive to donate, and reflected in a larger amplitude of P3. Additionally, implications and future directions were discussed.