Not everyone's heart contracts to reward: Insensitivity to varying levels of reward in dysphoria

Reward insensitivity in depression and dysphoria has been demonstrated by self-report, behavioral, and neuroscience data. These findings show less anticipated and experienced pleasure to rewarding stimuli, no behavioral adaptation in anticipation of rewards, and altered functioning in reward-related brain areas. The present study expands previous research by using cardiovascular reactivity to three levels of reward as an indicator of effort mobilization. Undergraduates with low versus high depression scores worked on a cognitive task in anticipation of no, versus a small, versus a significant amount of money for successful task performance. Results of pre-ejection period and heart rate reactivity confirmed the expected linear increase as a function of reward value in nondysphoric participants and the expected blunted response across all reward levels in dysphoric participants. The present findings thus show that dysphoric individuals have a motivational deficit in terms of reduced effort-related cardiac reactivity when anticipating a monetary reward.     

Schizophrenic subtypes and differential responsiveness to reward and punishment

Variations in responsivity to primary, secondary asocial and interpersonal rewards and punishments between major schizophrenic subgroups were investigated in a probability learning study. The subgroups compared were process and reactive, paranoid and nonparanoid, long- and short-hospitalization, and long- and short-length of illness schizophrenics. No evidence of differential responsivity to these reward-punishment/modality combinations appeared between high and low scorers on any of the four schizophrenic subgrouping dimensions. The groups then were matched closely so that the effects of each individual difference measure could be evaluated independently of the other three. Again, no significant differences in responsiveness to the reinforcement/modality combinations appeared. The results do not support the view that any of the four dimensions relate to differential responsiveness to primary, secondary asocial or verbal reward or punishment-at least on relatively simple tasks.     

Reduced tolerance and cardiovascular response to ischemic pain in minor depression

BACKGROUND: A paradoxical association between a higher prevalence of clinical pain and a reduced sensitivity to brief experimental pain seems to exist during depression. METHODS: We assessed the responses to sustained ischemic pain produced by a maximal effort tourniquet procedure in 32 controls and 11 individuals with minor depression (Zung autoscale > or =50). Stethoscopic blood pressures and heart rates were monitored throughout the procedure. RESULTS: Measures of pain threshold, and measures of pain intensity and pain unpleasantness during the ischemic procedure were similar in depressed and control subjects. Yet, the overall numerical ratings of ischemic pain during the procedure was 28% higher and pain tolerance was 44% lower in depressed compared to control subjects. Clinical pain complaints were reported by 91% of depressed but only by 41% of control subjects (P = 0.01). Sustained ischemic pain induced significant elevations of systolic and mean arterial blood pressures in controls but not in depressed subjects. LIMITATIONS: The main limitation of the present study was the preponderance of females in the depressed group. Yet, we did not find significant gender differences in the sensory-affective and autonomic responses to ischemic pain in our sample. CONCLUSIONS: These findings suggest alterations in the sensory and autonomic nervous systems during minor depression.     

Sensitivity to punishment and reward omission: evidence from error-related ERP components

In a recent experiment [Boksem, M.A.S., Tops, M., Wester, A.E., Meijman, T.F., Lorist, M.M., 2006. Error-related ERP components and individual differences in punishment and reward sensitivity. Brain Research 1101, 92-101], we showed that error-related ERP components were related to punishment and reward sensitivity. The present study was conducted to further evaluate the relationship between punishment/reward sensitivity and these ERP components. Therefore, we scored our subjects on the BIS/BAS measures of punishment and reward sensitivity. Then, subjects performed one of two versions of a Flanker task: in one, they were financially punished for committing errors; in the other, they were financially rewarded for correct performance. Analyses of ERN/Ne amplitudes indicated significant interactions between personality measures of punishment (BIS) and reward (BAS) and actual punishment and reward, while analyses of Pe amplitudes showed significant interactions between personality measures of reward sensitivity and actual reward. We suggest that ERN/Ne amplitude is related to concerns over mistakes and depends on the level of aversion experienced by individual subjects for making these mistakes. Subjects that are highly sensitive to punishment are strongly motivated or engaged in avoiding punishment, while subjects sensitive to rewards are motivated to obtain rewards and therefore show high task engagement when rewards may be earned. The error-related ERP components appear to track this level of engagement in task performance.     

Tracking the hemodynamic responses to reward and punishment in the striatum

Research suggests that the basal ganglia complex is a major component of the neural circuitry that mediates reward-related processing. However, human studies have not yet characterized the response of the basal ganglia to an isolated reward, as has been done in animals. We developed an event-related functional magnetic resonance imaging paradigm to identify brain areas that are activated after presentation of a reward. Subjects guessed whether the value of a card was higher or lower than the number 5, with monetary rewards as an incentive for correct guesses. They received reward, punishment, or neutral feedback on different trials. Regions in the dorsal and ventral striatum were activated by the paradigm, showing differential responses to reward and punishment. Activation was sustained following a reward feedback, but decreased below baseline following a punishment feedback.     

Sensitivity to reward and punishment and the prefrontal cortex in major depression

BACKGROUND: Patients with major depressive disorder (MDD) show neuropsychological impairments, including deficient executive functions and altered sensitivity to reward and punishment. METHODS: Executive functions (Wisconsin Card Sorting Test, WCST) and contingency learning based on the cumulative effect of reward and punishment (Iowa Gambling Test, IGT) were assessed in 30 medicated patients with unipolar MDD and in 20 healthy control volunteers. In the classic ABCD version of the IGT, advantageous decks are characterized by immediate small reward but even smaller future punishment. In the modified EFGH version, advantageous decks are characterized by immediate large punishment but even larger future reward. RESULTS: Patients with MDD were impaired in the WCST and in the ABCD version of the IGT but showed normal performances on the EFGH task. Depression, but not executive dysfunctions, significantly predicted performances on the EFGH task: less severe depressive symptoms were associated with better performances on the EFGH task. LIMITATIONS: The sample size was small and only few neuropsychological tests were used. Unmedicated patients were not assessed. Individual personality style, response strategies, and behavioral impulsivity were not investigated. CONCLUSIONS: Medicated patients with MDD show altered sensitivity to reward and punishment: immediate large reward enhanced related response patterns even when the strategy was disadvantageous and immediate large punishment did not prohibit related response patterns. Impairments in emotional decision-making were not a pure consequence of executive dysfunctions.     

Abstract reward and punishment representations in the human orbitofrontal cortex

The orbitofrontal cortex (OFC) is implicated in emotion and emotion-related learning. Using event-related functional magnetic resonance imaging (fMRI), we measured brain activation in human subjects doing an emotion-related visual reversal-learning task in which choice of the correct stimulus led to a probabilistically determined 'monetary' reward and choice of the incorrect stimulus led to a monetary loss. Distinct areas of the OFC were activated by monetary rewards and punishments. Moreover, in these areas, we found a correlation between the magnitude of the brain activation and the magnitude of the rewards and punishments received. These findings indicate that one emotional involvement of the human orbitofrontal cortex is its representation of the magnitudes of abstract rewards and punishments, such as receiving or losing money.     

Effects of monetary reward and punishment on stimulus-preceding negativity

This study examined the effects of emotional valence on stimulus-preceding negativity (SPN) using reward and fine. A time estimation task under reward, punishment, combined, and control conditions was performed. Participants were rewarded for accurate responses in the reward condition, and were fined for incorrect estimations in the punishment condition. in the combined condition, correct responses were rewarded and incorrect responses were fined. In the control condition, neither a reward nor fine was used. Results showed a significant interaction of condition x hemisphere. The SPN at the left hemisphere was increased in the reward condition. For the punishment effect, although it evoked right hemisphere dominance, no conditional difference was apparent at the right hemisphere. These results suggest that the SPN is affected by positive emotion: The left hemisphere activation might represent a pleasant emotion accompanying monetary gain.     

It's about effort: Impact of implicit affect on cardiovascular response is context dependent

Based on the Implicit‐Affect‐Primes‐Effort model, we tested whether the effect of implicitly processed affect primes on cardiovascular responses is limited to settings that call for effort and in which implicit affect can inform about subjective task demand. Participants were presented with letter series and briefly flashed sadness versus happiness primes. Half of the participants were asked to memorize all occurring vowels (achievement context), while the other half merely watched the series (watching context). Responses of cardiac pre‐ejection period, heart rate, and systolic and diastolic blood pressure supported the predictions. As expected, in the challenging achievement‐context condition, happiness primes led to stronger cardiovascular reactivity than sadness primes. By contrast, reactivity was modest in both affect prime conditions when the participants merely watched the stimuli. That is, the impact of affect primes on cardiovascular responses was limited to a setting that directly called for effort mobilization.     

Agitated dysphoria after late-onset loss of response to antidepressants: a case report

BACKGROUND: Antidepressants can sometimes cause agitation, particularly in patients with bipolar disorder, but concern about such effects is generally limited to the first weeks and months of treatment. METHOD: Demonstration of the occurrence of agitated dysphoria after loss of response to an antidepressant following continuous administration through 7 years of euthymia; with a worsening on dose increase; and recurrence of agitation on re-exposure 1 year later; in a patient whose previous dysthymia and recurrent depressions had no recognizable manic or hypomanic features. RESULTS: Only when the antidepressant was removed, twice, was treatment an atypical antipsychotic and lithium effective. CONCLUSION: An antidepressant which has been effective for as long as 7 years may still carry risk of inducing agitated dysphoria, even in apparently unipolar depression. In some patients, clinical vigilance for antidepressant-induced dysphoria may be warranted for extended periods of time.     

Differential effects of reward and punishment on conscious and unconscious eye movements

Very little is known about how human movements are influenced by abstract rewards and punishments relevant for human behaviour. The purpose of this study was to expand our knowledge of the behavioural effects of monetary reward and punishment. We introduced a high and low reward and punishment scheme into an antisaccade task where trials were either rewarded for a correct response (+1 or +25p) or punished for an incorrect response (-1 or -25p). The monetary value of the trial was indicated by the go signal, so subjects had to both program the location of the movement and determine the valence in the short interval before the eye movement was executed. We analysed both correct antisaccade responses and prosaccade errors. Importantly, the errors in this task can be either conscious (recognised) or unconscious (unrecognised). Saccades in both high-reward and high-punishment trials were slowed compared to saccades in low-reward and low-punishment trials, respectively. Therefore, unlike moderate rewards only (Blaukopf and DiGirolamo in Exp Brain Res 167:654-659, 2005), combining rewards and punishments and increasing motivation levels leads to a delay in movement execution during high valence trials where all actions are slowed, even errors. However, unconscious errors were differentially affected as they were speeded when punishment was high. We conclude that reward and punishment similarly influence the programming of conscious movements, but the strong saliency for punishment affords unconscious errors immunity from this delay.     

Drift diffusion model of reward and punishment learning in rare alpha-synuclein gene carriers

To understand the cognitive effects of alpha-synuclein polymorphism, we employed a drift diffusion model (DDM) to analyze reward- and punishment-guided probabilistic learning task data of participants with the rare alpha-synuclein gene duplication and age- and education-matched controls. Overall, the DDM analysis showed that, relative to controls, asymptomatic alpha-synuclein gene duplication carriers had significantly increased learning from negative feedback, while they tended to show impaired learning from positive feedback. No significant differences were found in response caution, response bias, or motor/encoding time. We here discuss the implications of these computational findings to the understanding of the neural mechanism of alpha-synuclein gene duplication.     

Context dependence of the event-related brain potential associated with reward and punishment

The error-related negativity (ERN) is an event-related brain potential elicited by error commission and by presentation of feedback stimuli indicating incorrect performance. In this study, the authors report two experiments in which participants tried to learn to select between response options by trial and error, using feedback stimuli indicating monetary gains and losses. The results demonstrate that the amplitude of the ERN is determined by the value of the eliciting outcome relative to the range of outcomes possible, rather than by the objective value of the outcome. This result is discussed in terms of a recent theory that holds that the ERN reflects a reward prediction error signal associated with a neural system for reinforcement learning.     

Electrophysiological measures of conflict and reward processing are associated with decisions to engage in physical effort

Anterior cingulate cortex (ACC), a key brain region involved in cognitive control and decision making, is suggested to mediate effort- and value-based decision making, but the specific role of ACC in this process remains debated. Here we used frontal midline theta (FMT) and the reward positivity (RewP) to examine ACC function in a value-based decision making task requiring physical effort. We investigated whether (1) FMT power is sensitive to the difficulty of the decision or to selecting effortful actions, and (2) RewP is sensitive to the subjective value of reward outcomes as a function of effort investment. On each trial, participants chose to execute a low-effort or a high-effort behavior (that required squeezing a hand-dynamometer) to obtain smaller or larger rewards, respectively, while their brainwaves were recorded. We replicated prior findings that tonic FMT increased over the course of the hour-long task, which suggests increased application of control in the face of growing fatigue. RewP amplitude also increased following execution of high-effort compared to low-effort behavior, consistent with increased valuation of reward outcomes by ACC. Although neither phasic nor tonic FMT were associated with decision difficulty or effort selection per se, an exploratory analysis revealed that the interaction of phasic FMT and expected value of choice predicted effort choice. This interaction suggests that phasic FMT increases specifically under situations of decision difficulty when participants ultimately select a high-effort choice. These results point to a unique role for ACC in motivating and persisting at effortful behavior when decision conflict is high.     

Anterior cingulate neurons in the rat map anticipated effort and reward to their associated action sequences

Goal-directed behaviors require the consideration and expenditure of physical effort. The anterior cingulate cortex (ACC) appears to play an important role in evaluating effort and reward and in organizing goal-directed actions. Despite agreement regarding the involvement of the ACC in these processes, the way in which effort-, reward-, and motor-related information is registered by networks of ACC neurons is poorly understood. To contrast ACC responses to effort, reward, and motor behaviors, we trained rats on a reversal task in which the selected paths on a track determined the level of effort or reward. Effort was presented in the form of an obstacle that was climbed to obtain reward. We used single-unit recordings to identify neural correlates of effort- and reward-guided behaviors. During periods of outcome anticipation, 52% of recorded ACC neurons responded to the specific route taken to the reward while 21% responded prospectively to effort and 12% responded prospectively to reward. In addition, effort- and reward-selective neurons typically responded to the route, suggesting that these cells integrated motor-related activity with expectations of future outcomes. Furthermore, the activity of ACC neurons did not discriminate between choice and forced trials or respond to a more generalized measure of outcome value. Nearly all neural responses to effort and reward occurred after path selection and were restricted to discrete temporal/spatial stages of the task. Together, these findings support a role for the ACC in integrating route-specific actions, effort, and reward in the service of sustaining discrete movements through an effortful series of goal-directed actions.     

Psychophysiological response of ADHD children to reward and extinction

In this study, we examined heart rate and skin conductance levels of 18 children with attention-deficit hyperactivity disorder (ADHD) and 18 normal children as they performed a repetitive motor task during reward and extinction conditions. Fowles (1980, Psychophysiology, 17, 87–104; 1988, Psychophysiology, 25, 373–391) suggested that psychophysiological responsivity reflects activity in two of Gray's (1982, The neuropsychology of anxiety, Oxford University Press; 1987, The psychology of fear and stress, Cambridge University Press) motivational systems; heart rate reactivity during reward reflects activity in the behavioral activation system, and skin conductance reactivity during extinction reflects activity in the behavioral inhibition system. As predicted, control children showed increased heart rate when reward was present and increased skin conductance when reward was removed. Compared with controls, ADHD children failed to show increased skin conductance levels during extinction, suggesting a weak behavioral inhibition system. ADHD children also displayed faster heart rate habituation to reward.     

Neural response to reward and depressive symptoms in late childhood to early adolescence

Depression is a major public health concern, and the period from late childhood through early adolescence is a critical time in the development of depressive symptoms. In adults, depression and depressive symptoms are associated with a reduction in the feedback negativity (FN), an ERP component elicited by feedback indicating rewards versus losses. The current study sought to extend these findings to a sample of 64 children aged 8-13, and to examine developmental differences in the FN. Consistent with previous work in adults, higher depressive symptom scores were associated with a blunted FN across the sample. When responses to losses and gains were examined separately, only reduction in the response to monetary gain was associated with increased depressive symptoms. In the current study, the vast majority of children were pre-pubertal, and the FN was unrelated to both age and pubertal development. The FN may be an ideal biomarker for studying changes in reward sensitivity and depression that emerge as children transition through puberty.     

Prenatal protein malnutrition alters response to reward in adult rats

Developing rats were either malnourished or adequately nourished during the prenatal period by feeding their dams diets of 6% (low) or 25% (adequate) casein content 5 weeks prior to mating and throughout pregnancy. All pups received adequate nutrition from the day of birth onwards. In Experiment 1, male offspring aged 125 days were tested in a food-rewarded variable interval 2-min (VI 2') operant paradigm under three levels of body weight reduction (90%, 85% and 80% of their ad lib feeding weight). Previously malnourished rats showed significantly higher response rates than well-nourished controls at the 90% and 85% levels but not at the 80% level. In Experiment 2, behaviorally native male littermates aged 225 days were tested in a saccharin-solution-rewarded VI 2' operant task. The rate of receipt of reward within each daily session was found to differ in the two nutritional groups. Previously malnourished rats maintained a stable rate of reward throughout the session while the controls showed a rapid decline over the first 15-20 min. The higher rate of reward late in the session in Experiment 2 and the elevated response rate in the first two phases of Experiment 1 suggests that prenatal protein malnutrition increases subsequent responsiveness to reward.     

Mortality salience,effort, and cardiovascular response to a bar-press challenge: Remarkably nuanced effects of a death prime on heart performance

We presented participants with a bar-pressing challenge relevant to their identity after having exposed them to a prime that made their mortality more or less salient. For some participants, difficulty was low; for others, it was high; for the rest, it was unfixed. As expected, heart pre-ejection period responses—reflecting heart contraction force—were (a) stronger under high-salience conditions when difficulty was high and unfixed, but (b) low regardless of salience when difficulty was low. Findings bear out conceptually and extend results from a previous experiment. In doing so, they add substantively to a new line of support for terror management theory and document the predictive utility of a proposed blended analysis of associated effort processes. The blended analysis speaks to the way in which motives to manage existential terror should convert into active goal striving and to the impact that existential threat might have on aspects of autonomic arousal.