Ventral striatal and medial prefrontal BOLD activation is correlated with reward-related electrocortical activity: A combined ERP and fMRI study

Future Research Directions in the Positive Valence Systems: Measurement, Development, and Implications for Youth Unipolar Depression

The Positive Valence Systems (PVS) have been introduced by the National Institute of Mental Health as a domain to help organize multiple constructs focusing on reward-seeking behaviors. However, the initial working model for this domain is strongly influenced by adult constructs and measures. Thus, the present review focuses on extending the PVS into a developmental context. Specifically, the review provides some hypotheses about the structure of the PVS, how PVS components may change throughout development, how family history of depression may influence PVS development, and potential means of intervening on PVS function to reduce onsets of depression. Future research needs in each of these areas are highlighted.

The Feedback-related Negativity Codes Components of Abstract Inference during Reward-based Decision-making

Behavioral control is influenced not only by learning from the choices made and the rewards obtained but also by “what might have happened,” that is, inference about unchosen options and their fictive outcomes. Substantial progress has been made in understanding the neural signatures of direct learning from choices that are actually made and their associated rewards via reward prediction errors (RPEs). However, electrophysiological correlates of abstract inference in decision-making are less clear. One seminal theory suggests that the so-called feedback-related negativity (FRN), an ERP peaking 200–300 msec after a feedback stimulus at frontocentral sites of the scalp, codes RPEs. Hitherto, the FRN has been predominantly related to a so-called “model-free” RPE: The difference between the observed outcome and what had been expected. Here, by means of computational modeling of choice behavior, we show that individuals employ abstract, “double-update” inference on the task structure by concurrently tracking values of chosen stimuli (associated with observed outcomes) and unchosen stimuli (linked to fictive outcomes). In a parametric analysis, model-free RPEs as well as their modification because of abstract inference were regressed against single-trial FRN amplitudes. We demonstrate that components related to abstract inference uniquely explain variance in the FRN beyond model-free RPEs. These findings advance our understanding of the FRN and its role in behavioral adaptation. This might further the investigation of disturbed abstract inference, as proposed, for example, for psychiatric disorders, and its underlying neural correlates.

Individual differences in the time course of reward processing: Stage-specific links with depression and impulsivity

Reward dysfunction has been implicated in a wide range of psychological disorders, including internalizing and externalizing psychopathology. Basic neuroscience research has shown that reward is a multistage process, yet it is unclear how specific stages relate to individual differences in reward sensitivity. The current study utilized event-related potentials elicited during a monetary incentive task to parse sub-stages within anticipatory and consummatory reward processing. Effects of depressive symptoms and trait impulsivity were examined at each sub-stage (N=92). Reward anticipation modulated neural activity across three sub-stages: cue detection (cue-P3), approach behavior (contingent negative variation, CNV), and outcome anticipation (stimulus preceding negativity). Reward delivery modulated activity across two sub-stages: initial evaluation (reward positivity, RewP), and allocation of attention (feedback-P3). Sensation seeking predicted faster reaction times, as well as cue-P3 and RewP amplitudes. Depression and lack of premeditation interacted to predict CNV and RewP amplitudes. Results demonstrate that individual differences in reward functioning are stage-specific.

Objective and specific tracking of anhedonia via event-related potentials in individuals with cocaine use disorders

BACKGROUND

Hyposensitivity to non-drug reward, behaviorally manifested as anhedonia, is a hallmark of chronic substance use. Anhedonia is a transdiagnostic symptom underpinned by neurobiochemical disturbances in the reward circuit, yet an objective measure to assess anhedonia severity still eludes the field. We hypothesized that the Reward Positivity (RewP) component of the event-related potentials (ERPs) will specifically track anhedonia as the RewP is attributed to the same brain regions that are also implicated in anhedonia.

METHODS

Forty-six individuals with cocaine use disorders (iCUD) performed a gambling task predicting whether they would win or lose money on each trial, while ERP data was acquired. RewP in response to predicted win trials was extracted from the ERPs using the principal component analysis. State anhedonia and depression severity were assessed using the Cocaine Selective Severity Assessment (CSSA).

RESULTS

Although RewP amplitude correlated with both anhedonia and depression, only the RewP-anhedonia correlation survived a correction for depression severity. Further, a hierarchical multiple regression analysis revealed that anhedonia explained a significant amount of variance in the RewP amplitude, and this variance was significantly greater than that explained by demographics, severity and recency of drug use and even depression.

CONCLUSIONS

These results show that RewP amplitude in response to rewarded trials tracks state anhedonia severity in iCUD. We argue that this association is perhaps driven by the activity in the dopaminergic mesocorticolimbic reward pathway that may underlie anhedonia symptomology as well as modulate RewP amplitude.

Activation of Direct and Indirect Pathway Medium Spiny Neurons Drives Distinct Brain-wide Responses

A central theory of basal ganglia function is that striatal neurons expressing the D1 and D2 dopamine receptors exert opposing brain-wide influences. However, the causal influence of each population has never been measured at the whole-brain scale. Here, we selectively stimulated D1 or D2 receptor-expressing neurons while visualizing whole-brain activity with fMRI. Excitation of either inhibitory population evoked robust positive BOLD signals within striatum, while downstream regions exhibited significantly different and generally opposing responses consistent with-though not easily predicted from-contemporary models of basal ganglia function. Importantly, positive and negative signals within the striatum, thalamus, GPi, and STN were all associated with increases and decreases in single-unit activity, respectively. These findings provide direct evidence for the opposing influence of D1 and D2 receptor-expressing striatal neurons on brain-wide circuitry and extend the interpretability of fMRI studies by defining cell-type-specific contributions to the BOLD signal.

The mere presence of an outgroup member disrupts the brain's feedback-monitoring system

Much of human learning happens in the social world. A person's social identity-the groups to which they belong, the people with whom they identify-is a powerful cue that can affect our goal-directed behaviors, often implicitly. In the present experiment, we explored the underlying neural mechanisms driving these processes, testing hypotheses derived from social identity theory. In a within-subjects design, participants underwent a minimal group manipulation where they were randomly assigned to an arbitrary ingroup. In two blocks of the experiment, participants were asked to complete a task for money while being observed by an ingroup member and outgroup member separately. Results revealed that being observed by an ingroup or outgroup member led to divergent patterns of neural activity associated with feedback monitoring, namely the feedback-related negativity (FRN). Receiving feedback in the presence of an ingroup member produced a typical FRN signal, but the FRN was dampened while receiving feedback in the presence of an outgroup member. Further, this differentiated neural pattern was exaggerated in people who reported greater intergroup bias. Together, the mere presence of a person can alter how the brain adaptively monitors feedback, impairing the reinforcement learning signal when the person observing is an outgroup member.

How do we trust strangers? The neural correlates of decision making and outcome evaluation of generalized trust

This study investigates the brain correlates of decision making and outcome evaluation of generalized trust (i.e. trust in unfamiliar social agents)-a core component of social capital which facilitates civic cooperation and economic exchange. We measured 18 (9 male) Chinese participants' event-related potentials while they played the role of the trustor in a one-shot trust game with unspecified social agents (trustees) allegedly selected from a large representative sample. At the decision-making phase, greater N2 amplitudes were found for trustors' distrusting decisions compared to trusting decisions, which may reflect greater cognitive control exerted to distrust. Source localization identified the precentral gyrus as one possible neuronal generator of this N2 component. At the outcome evaluation phase, principal components analysis revealed that the so called feedback-related negativity was in fact driven by a reward positivity, which was greater in response to gain feedback compared to loss feedback. This reduced reward positivity following loss feedback may indicate that the absence of reward for trusting decisions was unexpected by the trustor. In addition, we found preliminary evidence suggesting that the decision-making processes may differ between high trustors and low trustors.

The stability of the feedback negativity and its relationship with depression during childhood and adolescence

Feedback negativity (FN) is an event-related potential elicited by monetary reward and loss; it is thought to relate to reward-related neural activity and has been linked to depression in children and adults. In the current study, we examined the stability of FN, and its relationship with depression in adolescents, over 2 years in 45 8- to 13-year-old children. From Time 1 to Time 2, FN in response to monetary loss and in response to monetary gain showed moderate to strong reliability (rs = .64 and .67, respectively); these relationships remained significant even when accounting for related variables. FN also demonstrated high within-session reliability. Moreover, the relationship between a blunted FN and greater depression observed at Time 1 was reproduced at Time 2, and the magnitude of FN at Time 1 predicted depressive symptomatology at Time 2. These findings are consistent with the hypothesis that FN and its relationship with depression remain consistent over the course of development, and that FN may prospectively predict later depressive symptomatology. The current results suggest that FN may be suitable as a biomarker of depressive symptoms during adolescence.

Blunted reward processing in remitted melancholic depression

Blunted reward response appears to be a trait-like marker of vulnerability for Major Depressive Disorder (MDD). As such, it should be present in remitted individuals; however, depression is a heterogeneous syndrome. Reward-related impairments may be more pronounced in individuals with melancholic depression. The present study examined neural responses to rewards in remitted melancholic depression (rMD; N = 29), remitted non-melancholic depression (rNMD; N = 56), and healthy controls (HC; N = 81). Event-related potentials to monetary gain and loss were recorded during a simple gambling paradigm. rMD was characterized by a blunted response to rewards relative to both the HC and the rNMD groups, who did not differ from one another. Moreover, the rMD and rNMD groups did not differ in course or severity of their past illnesses, or current depressive symptoms or functioning. Results suggest that blunted response to rewards may be a viable vulnerability marker for melancholic depression.

Reward-related neural dysfunction across depression and impulsivity: A dimensional approach

Recent theoretical models underline reward sensitivity as a potential endophenotype for major depressive disorder. Neural and behavioral evidence reveals depression is associated with reduced reward sensitivity. However, reward dysfunction is not unique to depression, as it is also common across disorders of poor impulse control. We examined the interrelationships of depression (Depression, Anxiety, and Stress Scale [DASS-21]) and impulsivity (UPPS-P Impulsive Behavior Scale) with reward sensitivity among a large, representative sample (N = 260). ERPs were recorded to isolate two neural indicators of consummatory reward processing: initial evaluation of rewards in the 250-350 ms time window postonset of feedback (reward positivity [RewP]), and salience to monetary outcomes (P3). Significant interactions were observed between depression and impulsivity facets across these two stages of reward processing: depression and positive urgency predicted RewP amplitude to reward outcomes (win vs. loss); depression and one other impulsivity trait, (lack of) premeditation, predicted P3 amplitude to monetary outcomes. Conversely, high symptoms of depression were related to three biobehavioral profiles: (1) blunted RewP in conjunction with high positive urgency, (2) combination of blunted RewP and low (lack of) premeditation, and (3) blunted P3 to monetary wins/losses, in conjunction with low (lack of) premeditation. Findings illustrate that reward-related dysfunctions may be optimally conceptualized when examining the interactions between dimensions of internalizing and externalizing psychopathology.

The temporal dynamics of reversal learning: P3 amplitude predicts valence-specific behavioral adjustment

Adapting behavior to dynamic stimulus-reward contingences is a core feature of reversal learning and a capacity thought to be critical to socio-emotional behavior. Impairment in reversal learning has been linked to multiple psychiatric outcomes, including depression, Parkinson's disorder, and substance abuse. A recent influential study introduced an innovative laboratory reversal-learning paradigm capable of disentangling the roles of feedback valence and expectancy. Here, we sought to use this paradigm in order to examine the time-course of reward and punishment learning using event-related potentials among a large, representative sample (N=101). Three distinct phases of processing were examined: initial feedback evaluation (reward positivity, or RewP), allocation of attention (P3), and sustained processing (late positive potential, or LPP). Results indicate a differential pattern of valence and expectancy across these processing stages: the RewP was uniquely related to valence (i.e., positive vs. negative feedback), the P3 was uniquely associated with expectancy (i.e., unexpected vs. expected feedback), and the LPP was sensitive to both valence and expectancy (i.e., main effects of each, but no interaction). The link between ERP amplitudes and behavioral performance was strongest for the P3, and this association was valence-specific. Overall, these findings highlight the potential utility of the P3 as a neural marker for feedback processing in reversal-based learning and establish a foundation for future research in clinical populations.

NEURAL REACTIVITY TO REWARD AS A PREDICTOR OF COGNITIVE BEHAVIORAL THERAPY RESPONSE IN ANXIETY AND DEPRESSION

BACKGROUND

Cognitive behavioral therapy (CBT) is a well-established treatment for anxiety and depression; however, response to CBT is heterogeneous across patients and many remain symptomatic after therapy, raising the need to identify prospective predictors for treatment planning. Altered neural processing of reward has been implicated in both depression and anxiety, and improving hedonic capacity is a goal of CBT. However, little is known about how neural response to reward relates to CBT outcomes in depression and anxiety. The current study used the reward positivity (RewP) event-related potential (ERP) component to examine whether neural reactivity to reward would predict CBT response in a sample of patients with anxiety without depression (n = 30) and comorbid anxiety and depression (CAD, n = 22).

METHODS

Participants completed a guessing reward ERP paradigm before completing 12 weeks of standard CBT.

RESULTS

The majority of the sample (68%; 35 out of 52 patients) responded to treatment, and those with a reduced RewP at baseline were more likely to respond to treatment. A reduced RewP was also associated with a greater pre-to-post CBT reduction in depressive symptoms among individuals with CAD, but not among individuals with pure anxiety.

CONCLUSIONS

CBT may be most beneficial in reducing depressive symptoms for individuals who demonstrate decreased reward reactivity prior to treatment. CBT may target reward brain function, leading to greater improvement in symptoms. These effects may be strongest, and therefore most meaningful, for individuals with reward-processing deficits prior to treatment.

Longitudinal Associations Between Preschool Disruptive Mood Dysregulation Disorder Symptoms and Neural Reactivity to Monetary Reward During Preadolescence

OBJECTIVE

Reward-processing abnormalities are thought to be a key feature of various psychiatric disorders and may also play a role in disruptive mood dysregulation disorder (DMDD), a new diagnosis in DSM-5. In the current study, we used event-related potentials (ERP) sensitive to monetary gains (i.e., the reward positivity [RewP]) and losses (i.e., the N200) to examine associations between symptoms of DMDD during early childhood and later reward processing during preadolescence.

METHODS

To assess early emerging DMDD symptoms in a large longitudinal community sample (n=373) of 3-year old children, we administered a diagnostic interview, Preschool Age Psychiatric Assessment (PAPA) with parents. At a later assessment, ∼6 years later, children completed a monetary reward task while an electroencephalogram (EEG) was recorded. Children's lifetime history of psychopathology was also assessed at that time using Kiddie-Schedule of Affective Disorders and Schizophrenia (K-SADS) with the child and parent.

RESULTS

Multiple regression analyses revealed that age 3 DMDD symptoms predicted an enhanced RewP to monetary rewards in preadolescence. This association is independent of demographics and lifetime history of symptoms of depression, any anxiety disorder, attention-deficit disorder, oppositional defiant disorder, or conduct disorder Conclusions: Early manifestations of DMDD in children as young as 3 years old predicted enhanced reward processing later in development. These findings add to the growing corpus of literature on the pathophysiology of DMDD, and underscore the predictive validity of preschool DMDD on a neural level.

Attentional Bias Predicts Increased Reward Salience and Risk Taking in Bipolar Disorder

BACKGROUND

There is amassing evidence that risky decision-making in bipolar disorder is related to reward-based differences in frontostriatal regions. However, the roles of early attentional and later cognitive processes remain unclear, limiting theoretical understanding and development of targeted interventions.

METHODS

Twenty euthymic bipolar disorder and 19 matched control participants played a Roulette task in which they won and lost money. Event-related potentials and source analysis were used to quantify predominantly sensory-attentional (N1), motivational salience (feedback-related negativities [FRN]), and cognitive appraisal (P300) stages of processing. We predicted that the bipolar disorder group would show increased N1, consistent with increased attentional orienting, and reduced FRN, consistent with a bias to perceive outcomes more favorably.

RESULTS

As predicted, the bipolar disorder group showed increased N1 and reduced FRN but no differences in P300. N1 amplitude was additionally associated with real-life risk taking, and N1 source activity was reduced in visual cortex but increased activity in precuneus, frontopolar, and premotor cortex, compared to those of controls.

CONCLUSIONS

These findings demonstrate an early attentional bias to reward that potentially drives risk taking by priming approach behavior and elevating reward salience in the frontostriatal pathway. Although later cognitive appraisals of these inputs may be relatively intact in remission, interventions targeting attention orienting may also be effective in long-term reduction of relapse.

Executive control- and reward-related neural processes associated with the opportunity to engage in voluntary dishonest moral decision making

Research has begun to examine the neurocognitive processes underlying voluntary moral decision making, which involves engaging in honest or dishonest behavior in a setting in which the individual is free to make his or her own moral decisions. Employing event-related potentials, we measured executive control-related and reward-related neural processes during an incentivized coin-guessing task in which participants had the opportunity to voluntarily engage in dishonest behavior, by overreporting their wins to maximize earnings. We report four primary findings: First, the opportunity to deceive recruited executive control processes involving conflict monitoring and conflict resolution, as evidenced by a higher N2 and a smaller P3. Second, processing the outcome of the coin flips engaged reward-related processes, as evidenced by a larger medial feedback negativity (MFN) for incorrect (loss) than for correct (win) guesses, reflecting a reward prediction error signal. Third, elevated executive control-related neural activity reflecting conflict resolution (i.e., an attenuated executive control P3) predicted a greater likelihood of engaging in overall deceptive behavior. Finally, whereas elevated reward-related neural activity (the reward P3) was associated with a greater likelihood of engaging in overall deceptive behavior, an elevated reward prediction error signal (MFN difference score) predicted increased trial-by-trial moral behavioral adjustment (i.e., a greater likelihood to overreport wins following a previous honest loss than following a previous honest win trial). Collectively, these findings suggest that both executive control- and reward-related neural processes are implicated in moral decision making.

Using fMRI to study reward processing in humans: past, present, and future

Functional magnetic resonance imaging (fMRI) is a noninvasive tool used to probe cognitive and affective processes. Although fMRI provides indirect measures of neural activity, the advent of fMRI has allowed for1) the corroboration of significant animal findings in the human brain, and2) the expansion of models to include more common human attributes that inform behavior. In this review, we briefly consider the neural basis of the blood oxygenation level dependent signal to set up a discussion of how fMRI studies have applied it in examining cognitive models in humans and the promise of using fMRI to advance such models. Specifically, we illustrate the contribution that fMRI has made to the study of reward processing, focusing on the role of the striatum in encoding reward-related learning signals that drive anticipatory and consummatory behaviors. For instance, we discuss how fMRI can be used to link neural signals (e.g., striatal responses to rewards) to individual differences in behavior and traits. While this functional segregation approach has been constructive to our understanding of reward-related functions, many fMRI studies have also benefitted from a functional integration approach that takes into account how interconnected regions (e.g., corticostriatal circuits) contribute to reward processing. We contend that future work using fMRI will profit from using a multimodal approach, such as combining fMRI with noninvasive brain stimulation tools (e.g., transcranial electrical stimulation), that can identify causal mechanisms underlying reward processing. Consequently, advancements in implementing fMRI will promise new translational opportunities to inform our understanding of psychopathologies.

Blunted neural responses to reward in remitted major depression: A high-density event-related potential study

BACKGROUND

Major depressive disorder (MDD) is a highly recurrent condition, and improving our understanding of the abnormalities that persist in remitted MDD (rMDD) may provide insight into mechanisms that contribute to relapse. MDD has been characterized by reward learning deficits linked to dysfunction in frontostriatal regions. Although initial behavioral evidence of reward learning deficits in rMDD has recently emerged, it is unclear whether these reflect impairments in neural reward processing that persist into remission.

METHODS

We examined behavioral reward learning and 128-channel event-related potentials (ERP) during a well-validated probabilistic reward task in 26 rMDD individuals and 34 never-depressed controls. Temporo-spatial principal components analysis (PCA) was used to separate overlapping ERP components, and group differences in neural activity in a priori regions were examined using low-resolution electromagnetic tomography (LORETA).

RESULTS

Individuals with rMDD displayed reduced behavioral reward learning, as well as blunted ERP amplitude to reward feedback. Importantly, the reduction in ERP amplitude occurred at a PCA factor that peaked during the time at which phasic reward feedback-related signaling - hypothesized to originate in the striatum and project to the anterior cingulate cortex (ACC) - are thought to modulate scalp-recorded activity. Consistent with this, LORETA analyses revealed reduced activity in the ACC in the rMDD group, and this blunting correlated with poorer reward learning.

CONCLUSION

These findings suggest that the reward learning impairment observed in acute MDD persists into full remission and that these impairments may be attributable to abnormalities in the neural processes that support reward feedback monitoring, particularly within the ACC.

Left medial orbitofrontal cortex volume correlates with skydive-elicited euphoric experience

The medial orbitofrontal cortex has been linked to the experience of positive affect. Greater medial orbitofrontal cortex volume is associated with greater expression of positive affect and reduced medial orbital frontal cortex volume is associated with blunted positive affect. However, little is known about the experience of euphoria, or extreme joy, and how this state may relate to variability in medial orbitofrontal cortex structure. To test the hypothesis that variability in euphoric experience correlates with the volume of the medial orbitofrontal cortex, we measured individuals' (N = 31) level of self-reported euphoria in response to a highly anticipated first time skydive and measured orbitofrontal cortical volumes with structural magnetic resonance imaging. Skydiving elicited a large increase in self-reported euphoria. Participants' euphoric experience was predicted by the volume of their left medial orbitofrontal cortex such that, the greater the volume, the greater the euphoria. Further analyses indicated that the left medial orbitofrontal cortex and amygdalo-hippocampal complex independently explain variability in euphoric experience and that medial orbitofrontal cortex volume, in conjunction with other structures within the mOFC-centered corticolimbic circuit, can be used to predict individuals' euphoric experience.

Negative childhood experiences alter a prefrontal-insular-motor cortical network in healthy adults: A preliminary multimodal rsfMRI-fMRI-MRS-dMRI study

Research in humans and animals has shown that negative childhood experiences (NCE) can have long-term effects on the structure and function of the brain. Alterations have been noted in grey and white matter, in the brain's resting state, on the glutamatergic system, and on neural and behavioural responses to aversive stimuli. These effects can be linked to psychiatric disorder such as depression and anxiety disorders that are influenced by excessive exposure to early life stressors. The aim of the current study was to investigate the effect of NCEs on these systems. Resting state functional MRI (rsfMRI), aversion task fMRI, glutamate magnetic resonance spectroscopy (MRS), and diffusion magnetic resonance imaging (dMRI) were combined with the Childhood Trauma Questionnaire (CTQ) in healthy subjects to examine the impact of NCEs on the brain. Low CTQ scores, a measure of NCEs, were related to higher resting state glutamate levels and higher resting state entropy in the medial prefrontal cortex (mPFC). CTQ scores, mPFC glutamate and entropy, correlated with neural BOLD responses to the anticipation of aversive stimuli in regions throughout the aversion-related network, with strong correlations between all measures in the motor cortex and left insula. Structural connectivity strength, measured using mean fractional anisotropy, between the mPFC and left insula correlated to aversion-related signal changes in the motor cortex. These findings highlight the impact of NCEs on multiple inter-related brain systems. In particular, they highlight the role of a prefrontal-insular-motor cortical network in the processing and responsivity to aversive stimuli and its potential adaptability by NCEs.

Neural Basis of Intrinsic Motivation: Evidence from Event-Related Potentials

Human intrinsic motivation is of great importance in human behavior. However, although researchers have focused on this topic for decades, its neural basis was still unclear. The current study employed event-related potentials to investigate the neural disparity between an interesting stop-watch (SW) task and a boring watch-stop task (WS) to understand the neural mechanisms of intrinsic motivation. Our data showed that, in the cue priming stage, the cue of the SW task elicited smaller N2 amplitude than that of the WS task. Furthermore, in the outcome feedback stage, the outcome of the SW task induced smaller FRN amplitude and larger P300 amplitude than that of the WS task. These results suggested that human intrinsic motivation did exist and that it can be detected at the neural level. Furthermore, intrinsic motivation could be quantitatively indexed by the amplitude of ERP components, such as N2, FRN, and P300, in the cue priming stage or feedback stage. Quantitative measurements would also be convenient for intrinsic motivation to be added as a candidate social factor in the construction of a machine learning model.

Convergence of EEG and fMRI measures of reward anticipation

Deficits in reward anticipation are putative mechanisms for multiple psychopathologies. Research indicates that these deficits are characterized by reduced left (relative to right) frontal electroencephalogram (EEG) activity and blood oxygenation level-dependent (BOLD) signal abnormalities in mesolimbic and prefrontal neural regions during reward anticipation. Although it is often assumed that these two measures capture similar mechanisms, no study to our knowledge has directly examined the convergence between frontal EEG alpha asymmetry and functional magnetic resonance imaging (fMRI) during reward anticipation in the same sample. Therefore, the aim of the current study was to investigate if and where in the brain frontal EEG alpha asymmetry and fMRI measures were correlated in a sample of 40 adults. All participants completed two analogous reward anticipation tasks--once during EEG data collection and the other during fMRI data collection. Results indicated that the two measures do converge and that during reward anticipation, increased relative left frontal activity is associated with increased left anterior cingulate cortex (ACC)/medial prefrontal cortex (mPFC) and left orbitofrontal cortex (OFC) activation. This suggests that the two measures may similarly capture PFC functioning, which is noteworthy given the role of these regions in reward processing and the pathophysiology of disorders such as depression and schizophrenia.

Neural reactivity to rewards and losses in offspring of mothers and fathers with histories of depressive and anxiety disorders

Depression appears to be characterized by reduced neural reactivity to receipt of reward. Despite evidence of shared etiologies and high rates of comorbidity between depression and anxiety, this abnormality may be relatively specific to depression. However, it is unclear whether children at risk for depression also exhibit abnormal reward responding, and if so, whether risk for anxiety moderates this association. The feedback negativity (FN) is an event-related potential component sensitive to receipt of rewards versus losses that is reduced in depression. Using a large community sample (N = 407) of 9-year-old children who had never experienced a depressive episode, we examined whether histories of depression and anxiety in their parents were associated with the FN following monetary rewards and losses. Results indicated that maternal history of depression was associated with a blunted FN in offspring, but only when there was no maternal history of anxiety. In addition, greater severity of maternal depression was associated with greater blunting of the FN in children. No effects of paternal psychopathology were observed. Results suggest that blunted reactivity to rewards versus losses may be a vulnerability marker that is specific to pure depression, but is not evident when there is also familial risk for anxiety. In addition, these findings suggest that abnormal reward responding is evident as early as middle childhood, several years prior to the sharp increase in the prevalence of depression and rapid changes in neural reward circuitry in adolescence.

Individual differences in the habitual use of cognitive reappraisal predict the reward-related processing

Recent studies have shown that instructed cognitive reappraisal can regulate the neural processing of reward. However, it is still unclear whether the habitual use of cognitive reappraisal in everyday life is related to brain activity involved in reward processing. In the present study, participants' neural responses to reward were measured using electroencephalography (EEG) recorded during a gambling task and their tendency to use cognitive reappraisal was assessed using the Emotion Regulation Questionnaire (ERQ). Event-related potential (ERP) results indicated that losses on the gambling task elicited greater negative reward-related feedback negativity (FN) than gains. The differential FN between losses and gains was significantly correlated with cognitive reappraisal scores across participants such that individuals with a higher tendency to use cognitive reappraisal showed stronger reward processing (i.e., amplified FN difference between losses and gains). This correlation remained significant after controlling for expressive suppression scores. However, expressive suppression per se was not correlated with FN differences. Taken together, these results suggest that the habitual use of cognitive reappraisal is associated with increased neural processing of reward.

Blunted neural response to rewards as a vulnerability factor for depression: Results from a family study

Depressive disorders are associated with significant economic and public health burdens as well as increased morbidity. Yet, perhaps due to the heterogeneous nature of the disease, prevention and intervention efforts are only moderately efficacious. A better understanding of core mechanisms of depressive disorders might aid in the development of more targeted intervention, and perhaps help identify individuals at risk. One mechanism that may be particularly important to depressive phenotypes is reward insensitivity. Examination of neurobiological correlates of reward-processing, which should relate more directly to the neuropathology of depression, may be helpful in identifying liability for the disorder. To that end, we used a family study design to examine whether a neural response to rewards is a familial risk factor for depression in a sample of probands with a wide range of internalizing psychopathology, as well as their biological siblings. Event-related potentials were recorded during a simple forced-choice gambling paradigm, in which participants could either win or lose small amounts of money. Lower levels of positive affect in probands predicted a reduced neural response to rewards in siblings, even over and above the sibling's own level of positive and negative affect. Additionally, the neural response to rewards was familial (i.e., correlated among siblings). Combined, these analyses suggest that a blunted neural response to rewards may be useful in identifying individuals vulnerable to depressive illnesses.

Anterior cingulate activity to monetary loss and basal ganglia activity to monetary gain uniquely contribute to the feedback negativity

OBJECTIVE

The feedback negativity (FN) is an event-related potential that differentiates unfavorable versus favorable outcomes. Although thought to reflect error-related activity within the anterior cingulate cortex, recent work indicates the FN may also reflect reward-related activity that has been linked to the basal ganglia. To date, it remains unclear how to reconcile these conflicting perspectives.

METHODS

We decomposed the FN by applying time-frequency analysis to isolate activity unique to monetary losses and gains. The FN was recorded from 84 individuals during a laboratory gambling task.

RESULTS

Two signals contributed to the FN elicited by unpredictable outcomes: theta activity (4-7Hz) was increased following monetary loss, and delta activity (<3Hz) was increased following monetary gain. Predictable outcomes elicited delta but not theta activity. Source analysis revealed distinct generators, with loss-related theta localized to the anterior cingulate cortex and gain-related delta to a possible source in the striatum. Symptoms of depression, anxiety, and stress reactivity were specifically associated with blunted gain-related delta.

CONCLUSIONS

The FN may be a composite of loss- and gain-related neural activity, reflecting distinct facets of reward processing.

SIGNIFICANCE

Gain-related delta activity may provide unique information about reward dysfunction in major depression and other internalizing psychopathology.

Neural reactivity to monetary rewards and losses differentiates social from generalized anxiety in children

BACKGROUND

The relationship between reward sensitivity and pediatric anxiety is poorly understood. Evidence suggests that alterations in reward processing are more characteristic of depressive than anxiety disorders. However, some studies have reported that anxiety disorders are also associated with perturbations in reward processing. Heterogeneity in the forms of anxiety studied may account for the differences between studies. We used the feedback-negativity, an event-related potential sensitive to monetary gains versus losses (ΔFN), to examine whether different forms of youth anxiety symptoms were uniquely associated with reward sensitivity as indexed by neural reactivity to the receipt of positive and negative monetary outcomes.

METHOD

Participants were 390, eight- to ten-year-old children (175 females) from a large community sample. The ΔFN was measured during a monetary reward task. Self-reports of child anxiety and depression symptoms and temperamental positive emotionality (PE) were obtained.

RESULTS

Multiple regression analysis revealed that social anxiety and generalized anxiety symptoms were unique predictors of reward sensitivity after accounting for concurrent depressive symptoms and PE. While social anxiety was associated with a greater ΔFN, generalized anxiety was associated with a reduced ΔFN.

CONCLUSIONS

Different symptom dimensions of child anxiety are differentially related to alterations in reward sensitivity. This may, in part, explain inconsistent findings in the literature regarding reward processing in anxiety.

Impaired neural response to negative prediction errors in cocaine addiction

Learning can be guided by unexpected success or failure, signaled via dopaminergic positive reward prediction error (+RPE) and negative reward-prediction error (-RPE) signals, respectively. Despite conflicting empirical evidence, RPE signaling is thought to be impaired in drug addiction. To resolve this outstanding question, we studied as a measure of RPE the feedback negativity (FN) that is sensitive to both reward and the violation of expectation. We examined FN in 25 healthy controls; 25 individuals with cocaine-use disorder (CUD) who tested positive for cocaine on the study day (CUD+), indicating cocaine use within the past 72 h; and in 25 individuals with CUD who tested negative for cocaine (CUD-). EEG was acquired while the participants performed a gambling task predicting whether they would win or lose money on each trial given three known win probabilities (25, 50, or 75%). FN was scored for the period in each trial when the actual outcome (win or loss) was revealed. A significant interaction between prediction, outcome, and group revealed that controls showed increased FN to unpredicted compared with predicted wins (i.e., intact +RPE) and decreased FN to unpredicted compared with predicted losses (i.e., intact -RPE). However, neither CUD subgroup showed FN modulation to loss (i.e., impaired -RPE), and unlike CUD+ individuals, CUD- individuals also did not show FN modulation to win (i.e., impaired +RPE). Thus, using FN, the current study directly documents -RPE deficits in CUD individuals. The mechanisms underlying -RPE signaling impairments in addiction may contribute to the disadvantageous nature of excessive drug use, which can persist despite repeated unfavorable life experiences (e.g., frequent incarcerations).

Apathy in Parkinson's disease: clinical features, neural substrates, diagnosis, and treatment

Normal maintenance of human motivation depends on the integrity of subcortical structures that link the prefrontal cortex with the limbic system. Structural and functional disruption of different networks within these circuits alters the maintenance of spontaneous mental activity and the capacity of affected individuals to associate emotions with complex stimuli. The clinical manifestations of these changes include a continuum of abnormalities in goal-oriented behaviours known as apathy. Apathy is highly prevalent in Parkinson's disease (and across many neurodegenerative disorders) and can severely affect the quality of life of both patients and caregivers. Differentiation of apathy from depression, and discrimination of its cognitive, emotional, and auto-activation components could guide an individualised approach to the treatment of symptoms. The opportunity to manipulate dopaminergic treatment in Parkinson's disease allows researchers to study a continuous range of motivational states, from apathy to impulse control disorders. Parkinson's disease can thus be viewed as a model that provides insight into the neural substrates of apathy.

Blunted neural responses to monetary risk in high sensation seekers

The sensation-seeking trait is a valid predictor of various risk-taking behaviors. However, the neural underpinnings of risk processing in sensation seeking are yet unclear. The present event-related potential (ERP) study examined electrophysiological correlates associated with different stages of risky reward processing in sensation seeking. Twenty-one high sensation seekers (HSS) and 22 low sensation seekers (LSS) performed a simple two-choice gambling task. Behaviorally, whereas LSS exhibited a risk-averse pattern, HSS showed a risk-neutral pattern. During the anticipation stage, an increased stimulus-preceding negativity was elicited by high-risk compared to low-risk choices in LSS but not in HSS. During the outcome-appraisal stage, the feedback-related negativity, when calculated as the difference between losses and gains, was enhanced in response to the high-risk versus low-risk outcomes, which appeared for LSS but not for HSS. Further, HSS as compared to LSS exhibited a diminished P300 to both gains and losses. These findings suggest that risk-taking behavior in sensation seeking is expressed as blunted neural responses to risk in the anticipation stage and in the outcome-appraisal stage, which represents a candidate target for drug prevention.

The reward positivity: from basic research on reward to a biomarker for depression

Feedback indicating monetary loss elicits an apparent negative deflection in the event-related potential (ERP) that has been referred to as the feedback error-related negativity, medial frontal negativity, feedback-related negativity, and feedback negativity-all conceptualizations that suggest a negative ERP component that is greater for loss than gain. In the current paper, I review a programmatic line of research indicating that this apparent negativity actually reflects a reward-related positivity (RewP) that is absent or suppressed following nonreward. I situate the RewP within a broader nomological network of reward processing and individual differences in sensitivity to rewards. Further, I review work linking reductions in the RewP to increased depressive symptoms and risk for depression. Finally, I discuss future directions for research on the RewP.

Impaired reward processing by anterior cingulate cortex in children with attention deficit hyperactivity disorder

Decades of research have examined the neurocognitive mechanisms of cognitive control, but the motivational factors underlying task selection and performance remain to be elucidated. We recently proposed that anterior cingulate cortex (ACC) utilizes reward prediction error signals carried by the midbrain dopamine system to learn the value of tasks according to the principles of hierarchical reinforcement learning. According to this position, disruption of the ACC-dopamine interface can disrupt the selection and execution of extended, task-related behaviors. To investigate this issue, we recorded the event-related brain potential (ERP) from children with attention deficit hyperactivity disorder (ADHD), which is strongly associated with ACC-dopamine dysfunction, and from typically developing children while they navigated a simple "virtual T-maze" to find rewards. Depending on the condition, the feedback stimuli on each trial indicated that the children earned or failed to earn either money or points. We found that the reward positivity, an ERP component proposed to index the impact of dopamine-related reward signals on ACC, was significantly larger with money feedback than with points feedback for the children with ADHD, but not for the typically developing children. These results suggest that disruption of the ACC-dopamine interface may underlie the impairments in motivational control observed in childhood ADHD.