Differentiating stages of reward responsiveness: Neurophysiological measures and associations with facets of the behavioral activation system

Psychometric Properties of the Neural Response to Rewards and Errors Across Mid- to Late-Adolescence

Event-related potential (ERP) measures of reward- and error-related brain activity have been used to elucidate neural mechanisms contributing to the development of psychopathology. Adolescence is a critical developmental period that is associated with changes in ERP reward- and error-related brain activity. However, there is a paucity of within-subject research examining whether the reliability of ERP measures is the same or changes across adolescence. Moreover, it is unclear whether the time-frequency representation of reward- and error-related brain activity demonstrates similar psychometric properties. The present study examined the psychometric properties of reward- and error-related brain activity in five hundred and fifty 13.5- to 15.5-year-old (M = 14.4, SD = 0.63) girls. Participants completed the doors and flanker tasks while electroencephalography (EEG) was recorded at two assessments: baseline and 3 years later. Reward- and error-related brain activity were quantified using the time-domain reward positivity (RewP) and error-related negativity (ERN), respectively, as well as time-frequency delta and theta activity. Results indicated that all measures demonstrated adequate split-half reliability at each assessment and 3-year test-retest reliability across assessments. The present study indicates that the psychometric properties of time-domain and time-frequency reward- and error-related brain activity are largely consistent across adolescence, supporting their potential use as individual differences measures of risk for psychopathology.

Theta-Gamma Decoupling - A neurophysiological marker of impaired reward processing in Parkinson's disease

Individuals with Parkinson's disease (PD) exhibit altered reward processing, reflected by a decreased amplitude of an event-related potential (ERP) marker called reward positivity (RewP). Most studies have used RewP to investigate reward behavior due to the high temporal resolution of EEG and its high sensitivity. However, traditional single-electrode ERP analyses often overlook the intricate dynamics of non-phase-locked oscillatory activity and the complex interactions within these neural oscillatory patterns. Studying oscillatory activity is crucial as it provides mechanistic insights into the functional, spatial, and temporal aspects of neuronal processing. To address this gap, we employed a data-driven approach to identify EEG-based markers associated with PD reward processing deficits. Using an openly available 64-channel EEG dataset of 28 age- and sex-matched PD and control participants during a reinforcement learning task, we conducted a comprehensive secondary analysis. First, we employed a cluster-based permutation method to extract ERP markers, finding a consistent decrease in reward positivity in PD, regardless of medication status. Additionally, through region of interest (ROI) analysis on time-frequency data, we identified specific oscillatory patterns during reward processing. PD patients exhibited attenuated theta power and increased gamma power compared to healthy controls (HC). Notably, within the PD group, those off medication showed anterior localization of high gamma power, while those on medication displayed higher posterior gamma power. Building upon these findings, we explored phase-amplitude coupling between theta phase and gamma amplitude measured by the modulation index. We observed a trend of decreased theta-gamma coupling in PD patients, with statistically significant differences between on and off medication conditions. These results highlight the potential role of theta-gamma coupling as a neuromodulatory target for improving goal-oriented behavior in PD. Our correlation analyses suggest that high gamma power is linked to longer disease duration, while reduced reward positivity and low theta-gamma coupling may serve as markers of the dopaminergic impact on reward processing. Thus, our study unveils the intricate time-frequency dynamics underlying reward processing deficits in PD, emphasizing the utility of a data-driven approach to elucidate neural mechanisms and to identify potential therapeutic targets.

Altered Social Processing as a Potential Mechanism of BPD Risk in Girls with ADHD: A Call for Multi-Method Developmental Research

Childhood attention-deficit/hyperactivity disorder (ADHD) symptoms prospectively predict the development of borderline personality disorder (BPD) symptoms in adolescence and adulthood; adult women with BPD, in particular, often retrospectively report childhood ADHD symptoms. However, little is known about specific developmental pathways and mechanisms that contribute to this sequential comorbidity. Herein we outline a call for multi-method developmental research examining altered social processing as a potential mechanism underlying risk for BPD in girls with ADHD. We review relevant developmental psychopathology theory, describe recent empirical work, and outline steps for future work with the goal of promoting continued research focused on reducing the personal and societal burden associated with ADHD and BPD.

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.

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.

Beyond single paradigms, pipelines, and outcomes: Embracing multiverse analyses in psychophysiology

Psychophysiological research is an inherently complex undertaking due to the nature of the data, and its analysis is characterized by many decision points that shape the final dataset and a study's findings. These decisions create a "multiverse" of possible outcomes, and each decision from study conceptualization to statistical analysis can lead to different results and interpretations. This review describes the concept of multiverse analyses, a methodological approach designed to understand the impact of different decisions on the robustness of a study's findings and interpretation. The emphasis is on transparently showcasing different reasonable approaches for constructing a final dataset and on highlighting the influence of various decision points, from experimental design to data processing and outcome selection. For example, the choice of an experimental task can significantly impact event-related brain potential (ERP) scores or skin conductance responses (SCRs), and different tasks might elicit unique variances in each measure. This review underscores the importance of transparently embracing the flexibility inherent in psychophysiological research and the potential consequences of not understanding the fragility or robustness of experimental findings. By navigating the intricate terrain of the psychophysiological multiverse, this review serves as an introduction, helping researchers to make informed decisions, improve the collective understanding of psychophysiological findings, and push the boundaries of the field.

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.

The effects of stress on reward responsiveness: a systematic review and preliminary meta-analysis of the event-related potential literature

Exposure to stressful events is associated with a range of negative physical and mental health outcomes, including depression. It is critical to understand the mechanisms through which stress impacts mental health to identify promising targets for prevention and intervention efforts. Low-reward responsiveness is thought to be a mechanism of effects of stress on negative health outcomes and can be reliably measured at the neurophysiological level by using event-related potentials (ERPs), such as the reward positivity (RewP) component. The goal of this systematic review and preliminary meta-analysis was to examine evidence of associations between stress and alterations in reward responsiveness measured using ERPs. Through a systematic review of the literature, 23 studies examining the effects of laboratory-induced stressors and naturalistic stressors or perceived stress on reward responsiveness met study criteria, 13 of which were included in the meta-analysis. Most studies were conducted in undergraduate and community samples, with three selected for specific conditions, and primarily in adults. The systematic review supported evidence of associations between laboratory-induced stressors and blunted reward responsiveness as measured by the RewP but there were more mixed results when considering direct associations between naturalistic stressors/perceived stress and reward-related ERPs. Given that all studies examined the RewP, the meta-analysis focused on this component and indicated that there was a weak, nonsignificant negative association between stress and RewP. Results emphasize the complex nature of relations between stress and reward-related ERPs and the need to consider alternative models in future research. We also provide reporting recommendations for ERP researchers to facilitate future meta-analyses.

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.

Positive valence system function and anhedonia in middle-aged and older adults at high suicide risk

Positive valence systems are disrupted in late-life depression and in individuals at risk for suicide. The reward positivity (RewP) is an event-related potential measure of positive valence system function that relates to depression and anhedonia in children and young adults. However, it is unclear whether a reliable RewP signal can be elicited in middle-aged and older adults at high risk for suicide and, if so, whether this signal is similarly associated with clinical symptoms. In the current study, a RewP was elicited with a standard gambling task in middle-aged and older adults (N = 31) at discharge from a hospitalization for suicidal thought or behaviors. The resulting electrocortical response differed significantly for monetary wins compared to losses. Internal reliability of the RewP and the feedback negativity (FN) to monetary loss was good to excellent. Internal reliability of difference measures was lower but still largely acceptable, with residualized differences scores demonstrating stronger reliability than subtraction-based scores. A smaller residualized RewP, after accounting for the influence of the FN, was associated with greater severity of lassitude, an index of appetitive anhedonia. These findings set the groundwork for future studies of positive valence system function and depression in middle-aged and older adults at high risk for suicide.

Blunted reward responsiveness prospectively predicts emotional distress when exposed to a naturalistic stressor

Both stress and blunted reward responsiveness have been identified as core risk factors of depression. Whether blunted reward responsiveness increases psychological vulnerability to real-life stress from a dynamic perspective (from stress reactivity to recovery) has not been investigated. By utilizing a real-world stressful event (i.e. the final examination), this study aimed to explore the role of reward responsiveness in the stress-emotional distress relationship during stress reactivity and recovery phases. We followed 57 undergraduates with three assessments, from six weeks before examination weeks (T1, baseline), one day before the examinations (T2) to two weeks after the examinations (T3), therefore, covering stress reactivity (T1 to T2) and recovery (T2 to T3) phases. At baseline, reward responsiveness was measured as the Reward Positivity (RewP) in the doors task. Stress and emotional distress (anxiety and depression) were reported at T1, T2 and T3 to capture their dynamic changes. Results showed that self-report stress levels significantly increased from T1 to T2 (stress reactivity phase) and decreased from T2 to T3 (stress recovery phase). Furthermore, blunted reward responsiveness at baseline prospectively predicted emotional distress during the stress reactivity phase but not the recovery phase. Specifically, during the stress reactivity phase, higher perceived stress was associated with greater anxiety and depression only in participants with relatively smaller residual RewP amplitudes but not in participants with relatively larger residual RewP amplitudes. Our study demonstrated that a blunted reward responsiveness is a vulnerable factor of depression, especially when exposed to stress. Our findings provide insights into prevention and intervention for stress-related disturbance.

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.

Amphetamine alters an EEG marker of reward processing in humans and mice

The bench-to-bedside development of pro-cognitive therapeutics for psychiatric disorders has been mired by translational failures. This is, in part, due to the absence of pharmacologically sensitive cognitive biomarkers common to humans and rodents. Here, we describe a cross-species translational marker of reward processing that is sensitive to the aminergic agonist, d-amphetamine. Motivated by human electroencephalographic (EEG) findings, we recently reported that frontal midline delta-band power is an electrophysiological biomarker of reward surprise in humans and in mice. In the current series of experiments, we determined the impact of parametric doses of d-amphetamine on this reward-related EEG response from humans (n = 23) and mice (n = 28) performing a probabilistic learning task. In humans, d-amphetamine (placebo, 10 mg, 20 mg) boosted the Reward Positivity event-related potential (ERP) component as well as the spectral delta-band representations of this signal. In mice, d-amphetamine (placebo, 0.1 mg/kg, 0.3 mg/kg, 1.0 mg/kg) boosted both reward and punishment ERP features, yet there was no modulation of spectral activities. In sum, the present results confirm the role of dopamine in the generation of the Reward Positivity in humans, and pave the way toward a pharmacologically valid biomarker of reward sensitivity across species.