Executive deficits may play an important role in late-life suicide. Yet, current evidence in this area is inconclusive and does not indicate whether these deficits are broadly associated with suicidal ideation or specific to suicidal behavior. This study examined global cognition and specifically executive function impairments as correlates of suicidal ideation and suicidal behavior in depressed older adults, with the goal of extending an earlier preliminary study.
University-affiliated psychiatric hospital.
All were aged 60+: 83 depressed suicide attempters, 43 depressed individuals having suicidal ideation with a specific plan, 54 non-suicidal depressed participants, and 48 older adults with no history of psychiatric disorders.
Global cognitive function - Dementia Rating Scale (DRS), Executive function - Executive Interview (EXIT).
Both suicide attempters and suicide ideators performed worse than the two comparison groups on the EXIT, with no difference between suicide attempters and suicide ideators. On the DRS total score, as well as on Memory and Attention subscales, suicide attempters and ideators and non-suicidal depressed subjects performed similarly and were impaired relative to with non-psychiatric control subjects. Controlling for education, substance use disorders, and medication exposure did not affect group differences in performance on either the EXIT or DRS.
Executive deficits, captured with a brief instrument, are associated broadly with suicidal ideation in older depressed adults but do not appear to directly facilitate suicidal behavior. Our data are consistent with the idea that different vulnerabilities may operate at different stages in the suicidal process.
suicide; cognitive; executive function; depression; aged
Current treatment outcomes of Major Depressive Disorder (MDD) in adolescents remain suboptimal. Discriminating between state and trait markers of MDD in adolescents would help identify markers that may guide choice of appropriate interventions and help improve longer-term outcome for individuals with the illness.
We compared neurocognitive performance in executive function, sustained attention and short-term memory in 20 adolescents with MDD in acute episode (MDDa), 20 previously depressed adolescents in remission (MDDr) and 17 healthy control participants (HC).
There was a group difference that emerged for executive function with increasing task difficulty (p = 0.033). MDDa showed impaired executive function, as measured by using more moves to solve 4-move problems on a forward planning task, relative to MDDr and HC (p = 0.01, d = 0.94 and p = 0.015, d = 0.77 respectively). MDDa showed more impulsivity as measured by lower response bias (B″) on a sustained attention task than both MDDr and HC (p = 0.01, d = 0.85 and p = 0.008, d = 0.49 respectively). Higher impulsivity was associated with more severe depression (r = −0.365, p = 0.022) and earlier age of onset of depression (r = 0.402, p = 0.012) and there was a trend for a correlation between more executive dysfunction and more severe depression (r = 0.301 p = 0.059) in MDDa and MDDr combined. The three groups did not differ significantly on short-term memory or target detection on the sustained attention task.
These results need to be replicated in the future with a larger sample size.
Executive dysfunction and impulsivity appear to be state-specific markers of MDD in adolescents that are related to depression severity and not present in remission.
Depression; Adolescent; Neurocognition; Executive function; Impulsivity
Frontostriatal circuitry is implicated in the cognitive distortions associated with gambling behaviour. ‘Near-miss’ events, where unsuccessful outcomes are proximal to a jackpot win, recruit overlapping neural circuitry with actual monetary wins. Personal control over a gamble (e.g., via choice) is also known to increase confidence in one's chances of winning (the ‘illusion of control’).
Using psychophysiological interaction (PPI) analyses, we examined changes in functional connectivity as regular gamblers and non-gambling participants played a slot-machine game that delivered wins, near-misses and full-misses, and manipulated personal control. We focussed on connectivity with striatal seed regions, and associations with gambling severity, using voxel-wise regression.
For the interaction term of near-misses (versus full-misses) by personal choice (participant-chosen versus computer-chosen), ventral striatal connectivity with the insula, bilaterally, was positively correlated with gambling severity. In addition, some effects for the contrast of wins compared to all non-wins were observed at an uncorrected (p < .001) threshold: there was an overall increase in connectivity between the striatal seeds and left orbitofrontal cortex and posterior insula, and a negative correlation for gambling severity with the connectivity between the right ventral striatal seed and left anterior cingulate cortex.
These findings corroborate the ‘non-categorical’ nature of reward processing in gambling: near-misses and full-misses are objectively identical outcomes that are processed differentially. Ventral striatal connectivity with the insula correlated positively with gambling severity in the illusion of control contrast, which could be a risk factor for the cognitive distortions and loss-chasing that are characteristic of problem gambling.
Gambling; Connectivity; fMRI; Reward; Near-miss; Addiction
Gambling is pertinent to neuroscience research for at least two reasons. First, gambling is a naturalistic and pervasive example of risky decision making, and thus gambling games can provide a paradigm for the investigation of human choice behavior and “irrationality.” Second, excessive gambling involvement (i.e., pathological gambling) is currently conceptualized as a behavioral addiction, and research on this condition may provide insights into addictive mechanisms in the absence of exogenous drug effects. This article is a summary of topics covered in a Society for Neuroscience minisymposium, focusing on recent advances in understanding the neural basis of gambling behavior, including translational findings in rodents and nonhuman primates, which have begun to delineate neural circuitry and neurochemistry involved.
Suicide can be viewed as an escape from unendurable punishment at the cost of any future rewards. Could faulty estimation of these outcomes predispose to suicidal behavior? In behavioral studies, many of those who have attempted suicide misestimate expected rewards on gambling and probabilistic learning tasks.
To describe the neural circuit abnormalities that underlie disadvantageous choices in people at risk for suicide and to relate these abnormalities to impulsivity, which is one of the components of vulnerability to suicide.
Case-control functional magnetic resonance imaging study of reward learning using a reinforcement learning model.
University hospital and outpatient clinic.
Fifty-three participants 60 years or older, including 15 depressed patients who had attempted suicide, 18 depressed patients who had never attempted suicide (depressed control subjects), and 20 psychiatrically healthy controls.
MAIN OUTCOMES AND MEASURES
Components of the cortical blood oxygenation level–dependent response tracking expected and unpredicted rewards.
Depressed elderly participants displayed 2 distinct disruptions of control over reward-guided behavior. First, impulsivity and a history of suicide attempts (particularly poorly planned ones) were associated with a weakened expected reward signal in the paralimbic cortex, which in turn predicted the behavioral insensitivity to contingency change. Second, depression was associated with disrupted corticostriatothalamic encoding of unpredicted rewards, which in turn predicted the behavioral oversensitivity to punishment. These results were robust to the effects of possible brain damage from suicide attempts, depressive severity, co-occurring substance use and anxiety disorders, antidepressant and anticholinergic exposure, lifetime exposure to electroconvulsive therapy, vascular illness, and incipient dementia.
CONCLUSIONS AND RELEVANCE
Altered paralimbic reward signals and impulsivity and/or carelessness may facilitate unplanned suicidal acts. This pattern, also seen in gambling and cocaine use, may reflect a primary deficit in the paralimbic cortex or in its mesolimbic input. The overreactivity to punishment in depression may be caused in part by a disruption of appetitive learning in the corticostriatothalamic circuits.
Successful choice under risk requires the integration of information about outcome probabilities and values and implicates a brain network including the ventromedial prefrontal cortex (vmPFC) and posterior parietal cortex (pPAR). Damage to the vmPFC is linked to poor decision-making and increased risk-taking. Electrophysiological and neuroimaging data implicate the pPAR in the processing of reward probability during choice, but the causal contribution of this area has not been established. We compared patients with lesions to the pPAR (n = 13), vmPFC (n = 13), and healthy volunteers (n = 22) on the Roulette Betting Task, a measure of risk-sensitive decision-making. Both lesion groups were impaired in adjusting their bets to the probability of winning. This impairment was correlated with the extent of pPAR, but not vmPFC, damage. In addition, the vmPFC group chose higher bets than healthy controls overall, an effect that correlated with lesion volume in the medial orbitofrontal cortex. Both lesion groups earned fewer points than healthy controls. The groups did not differ on 2 tasks assessing probabilistic reasoning outside of a risk-reward context. Our results demonstrate the causal involvement of both the pPAR and vmPFC in risk-sensitive choice and indicate distinguishable roles of these areas in probability processing and risk appetite.
decision-making; lesion study; posterior parietal cortex; risk; ventromedial prefrontal cortex
Humans can resist temptations by exerting willpower, the effortful inhibition of impulses. But willpower can be disrupted by emotions and depleted over time. Luckily, humans can deploy alternative self-control strategies like precommitment, the voluntary restriction of access to temptations. Here, we examined the neural mechanisms of willpower and precommitment using fMRI. Behaviorally, precommitment facilitated choices for large delayed rewards, relative to willpower, especially in more impulsive individuals. While willpower was associated with activation in dorsolateral prefrontal cortex (DLPFC), posterior parietal cortex (PPC), and inferior frontal gyrus, precommitment engaged lateral frontopolar cortex (LFPC). During precommitment, LFPC showed increased functional connectivity with DLPFC and PPC, especially in more impulsive individuals, and the relationship between impulsivity and LFPC connectivity was mediated by value-related activation in ventromedial PFC. Our findings support a hierarchical model of self-control in which LFPC orchestrates precommitment by controlling action plans in more caudal prefrontal regions as a function of expected value.
•Precommitment is the voluntary restriction of access to temptations•Precommitment is a more effective self-control strategy than willpower•Precommitment engages LFPC; willpower engages DLPFC and PPC•During precommitment, LFPC increases connectivity with DLPFC and PPC
Crocket et al. show that during precommitment, which involves voluntarily restricting access to temptations, lateral frontopolar cortex is activated and increases functional connectivity with dorsolateral prefrontal and posterior parietal cortex—the same regions associated with actively resisting temptations.
Converging evidence implicates basal ganglia alterations in impulsivity and suicidal behavior. For example, D2/D3 agonists and subthalamic nucleus stimulation in Parkinson’s disease trigger impulse control disorders and possibly suicidal behavior. Further, suicidal behavior has been associated with structural basal ganglia abnormalities. Finally, low-lethality, unplanned suicide attempts are associated with increased discounting of delayed rewards, a behavior dependent upon the striatum. Thus, we tested whether, in late-life depression, changes in the basal ganglia were associated with suicide attempts and with increased delay discounting.
Fifty-two persons aged ≥60 underwent extensive clinical and cognitive characterization: 33 with major depression (13 suicide attempters [SA], 20 non-suicidal depressed elderly), and 19 non-depressed controls. Participants had high-resolution T1-weighted MPRAGE MRI scans. Basal ganglia gray matter voxel counts were estimated using atlas-based segmentation, with a highly-deformable automated algorithm. Discounting of delayed rewards was assessed using the Monetary Choice Questionnaire, and delay aversion with the Cambridge Gamble Task.
SA had lower putamen but not caudate or pallidum gray matter voxel counts, compared to the control groups. This difference persisted after accounting for substance use disorders and possible brain injury from suicide attempts. SA with lower putamen gray matter voxel counts displayed higher delay discounting on the MCQ, but not delay aversion on the CGT. Secondary analyses revealed that SA had lower voxel counts in associative and possibly ventral, but not sensorimotor striatum.
Our findings, while limited by small sample size and case-control design, suggest that striatal lesions could contribute to suicidal behavior by increasing impulsivity.
suicide; basal ganglia; corpus striatum; globus pallidus; putamen; decision making; reward
Alterations in appetitive processing are central to the major psychological theories of addiction, with differential predictions made by the reward deficiency, incentive salience, and impulsivity hypotheses. Functional MRI has become the chief means of testing these predictions, with experiments reliably highlighting disturbances at the level of the striatum, medial prefrontal cortex, and affiliated regions. However, demonstrations of hypo-reactivity and hyper-reactivity of this circuitry in drug addicted groups are reported in approximately equal measure. Similar findings are echoed in the emergent neuroimaging literature on pathological gambling, which has recently witnessed a coming of age. The first aim of this article is to consider some of the methodological aspects of these experiments that could influence the observed direction of group-level effects, including the baseline condition, trial structure and timing, and the nature of the appetitive cues (drug-related, monetary, or primary rewards). The second aim is to highlight the conceptual traction that is offered by pathological gambling, as a model of a ‘toxicity free’ addiction and an illness where tasks of monetary reinforcement afford a more direct mapping to the abused commodity. Our conclusion is that relatively subtle decisions in task design appear capable of driving group differences in fronto-striatal circuitry in entirely opposing directions, even with tasks and task variants that look ostensibly similar. Differentiation between the psychological theories of addiction will require a greater breadth of experimental designs, with more research needed on processing of primary appetitive cues, aversive processing, and in vulnerable/at-risk groups.
•We outline the current psychological theories of addiction and their predictions.•We review recent fMRI literature of substance addictions and appetitive processing.•Reasons for opposing results (hyper- vs hypo-active reward regions) are discussed.•Recent fMRI findings of appetitive processing in pathological gambling are reviewed.•Pathological gambling is suggested as a prototypical addiction for imaging research.
Addiction; Pathological gambling; fMRI; Ventral striatum; Appetitive processing
Late-life suicide is an under-investigated public health problem. Among the putative vulnerabilities for this complex multifactorial behaviour are deficits in cognitive control, an ability to integrate and prioritize multiple cognitive processes in order to flexibly adapt behaviour and meet situational demands. We investigated cognitive control during rule learning in a complex and changing environment in older individuals with suicide attempts of varying lethality.
Ninety-three participants over the age of 60 (30 healthy controls, 29 depressed never suicidal, 20 low-lethality suicide attempters, 14 high-lethality suicide attempters) underwent structured clinical and cognitive assessments. Participants then completed the Wisconsin Card Sorting Test (WCST), a well-studied task of cognitive control during rule learning.
High-lethality attempters demonstrated a pattern of deficits involving poor conceptual reasoning, perseverative errors and total errors. Compared to low-lethality attempters and healthy controls, high-lethality attempters demonstrated poor conceptual reasoning, as well as increased rates of perseverative errors and total errors. Compared to non-suicidal depressed participants, high-lethality attempters also made more conceptual errors.
High-lethality suicide attempts among older people are associated with impaired cognitive control during rule learning as detected by the WCST. Our data suggest that impairment in cognitive control during rule learning may represent a vulnerability distinct from the impulsive diathesis, typically manifesting in young, low-lethality attempters. This vulnerability may contribute to the high incidence of serious or, often, fatal suicidal acts in old age.
Suicide; Cognitive control; Cognitive function; Learning; Geriatrics; Depression
Gambling is characterized by cognitive distortions in the processing of chance and skill that are exacerbated in pathological gambling. Opioid and dopamine dysregulation is implicated in pathological gambling, but it is unclear whether these neurotransmitters modulate gambling distortions. The objective of the current study was to assess the effects of the opioid receptor antagonist naltrexone and the dopamine D2 receptor antagonist haloperidol on gambling behavior. Male recreational gamblers (n = 62) were assigned to receive single oral doses of naltrexone 50 mg, haloperidol 2 mg or placebo, in a parallel-groups design. At 2.5 h post-dosing, participants completed a slot machine task to elicit monetary wins, “near-misses,” and a manipulation of personal choice, and a roulette game to elicit two biases in sequential processing, the gambler's fallacy and the hot hand belief. Psychophysiological responses (electrodermal activity and heart rate) were taken during the slot machine task, and plasma prolactin increase was assessed. The tasks successfully induced the gambling effects of interest. Some of these effects differed across treatment groups, although the direction of effect was not in line with our predictions. Differences were driven by the naltrexone group, which displayed a greater physiological response to wins, and marginally higher confidence ratings on winning streaks. Prolactin levels increased in the naltrexone group, but did not differ between haloperidol and placebo, implying that naltrexone but not haloperidol may have been functionally active at these doses. Our results support opioid modulation of cognition during gambling-like tasks, but did not support the more specific hypothesis that naltrexone may act to ameliorate cognitive distortions.
naltrexone; haloperidol; pathological gambling; addiction; reward; motivation; decision-making; psychophysiology
Pathological gambling (PG) is a behavioural addiction associated with elevated impulsivity and suspected dopamine dysregulation. Reduced striatal dopamine D2/D3 receptor availability has been reported in drug addiction, and may constitute a premorbid vulnerability marker for addictive disorders. The aim of the present study was to assess striatal dopamine D2/D3 receptor availability in PG, and its association with trait impulsivity. Males with PG (n = 9) and male healthy controls (n = 9) underwent [11C]-raclopride positron emission tomography imaging and completed the UPPS-P impulsivity scale. There was no significant difference between groups in striatal dopamine D2/D3 receptor availability, in contrast to previous reports in drug addiction. However, mood-related impulsivity (‘Urgency’) was negatively correlated with [11C]-raclopride binding potentials in the PG group. The absence of a group difference in striatal dopamine binding implies a distinction between behavioural addictions and drug addictions. Nevertheless, our data indicate heterogeneity in dopamine receptor availability in disordered gambling, such that individuals with high mood-related impulsivity may show differential benefits from dopamine-based medications.
► Assessed 11C-raclopride binding in pathological gambling, a putative behavioral addiction. ► No group difference in striatal dopamine binding from healthy controls. ► Dopamine binding negatively correlated with mood-related impulsivity (‘Urgency’).
Gambling; Impulsivity; Dopamine; Neuroimaging; Addiction; Striatum
Updated theoretical accounts of the role of serotonin (5-HT) in motivation propose that 5-HT operates at the intersection of aversion and inhibition, promoting withdrawal in the face of aversive predictions. However, the specific cognitive mechanisms through which 5-HT modulates withdrawal behavior remain poorly understood. Behavioral inhibition in response to punishments reflects at least two concurrent processes: instrumental aversive predictions linking stimuli, responses, and punishments, and Pavlovian aversive predictions linking stimuli and punishments irrespective of response. In the current study, we examined to what extent 5-HT modulates the impact of instrumental vs Pavlovian aversive predictions on behavioral inhibition. We used acute tryptophan depletion to lower central 5-HT levels in healthy volunteers, and observed behavior in a novel task designed to measure the influence of Pavlovian and instrumental aversive predictions on choice (response bias) and response vigor (response latencies). After placebo treatment, participants were biased against responding on the button that led to punishment, and they were slower to respond in a punished context, relative to a non-punished context. Specifically, participants slowed their responses in the presence of stimuli predictive of punishments. Tryptophan depletion removed the bias against responding on the punished button, and abolished slowing in the presence of punished stimuli, irrespective of response. We suggest that this set of results can be explained by a role for 5-HT in Pavlovian aversive predictions. These findings suggest additional specificity for the influence of 5-HT on aversively motivated behavioral inhibition and extend recent models of the role of 5-HT in aversive predictions.
serotonin; aversion; inhibition; tryptophan; Pavlovian; instrumental; Serotonin; Cognition; Psychopharmacology; Behavioral Science; aversion; inhibition; tryptophan; Pavlovian; instrumental
The decision to commit suicide may be impulsive, but lethal suicidal acts often involve planning and forethought. People who attempt suicide make disadvantageous decisions in other contexts, but nothing is known about the way they decide about the future. Can the willingness to postpone future gratification differentiate between individuals prone to serious, premeditated and less serious, unplanned suicidal acts?
Four groups of depressed participants aged 60+ made choices between smaller immediate and larger delayed monetary rewards: 15 who made high-lethality suicide attempts, 14 who made low-lethality suicide attempts, 12 who seriously contemplated suicide, and 42 people with depression but no history of suicidal thoughts. The reference group was 31 psychiatrically healthy elders.
Individuals who had made low-lethality attempts displayed an exaggerated preference for immediate rewards compared to non-suicidal depressed and healthy controls. Those who had carried out high-lethality suicide attempts were more willing to delay future rewards, compared to low-lethality attempters. Better planned suicide attempts were also associated with willingness to wait for larger rewards. These effects were unchanged after accounting for education, global cognitive function, substance use disorders, psychotropic medications, and possible brain injury from attempts. Discount rates were correlated with having debt but were not significantly associated with income, hopelessness, depressive severity, premorbid IQ, age at first attempt, or choice of violent means.
While clinicians often focus on impulsivity in patients at risk for suicide, these data suggest that identifying biological characteristics and treatments for non-impulsive suicidal older people may be even more important.
suicide; cognition; decision making; reward; depressive disorder; aged; time perception; executive function; choice behavior
It has been robustly demonstrated using the ultimatum game (UG) that individuals frequently reject unfair financial offers even if this results in a personal cost. One influential hypothesis for these rejections is that they reflect an emotional reaction to unfairness that overrides purely economic decision processes. In the present study, we examined whether the interplay between bodily responses, bodily regulation, and bodily perception (“interoception”) contributes to emotionally driven rejection behavior on the UG. Offering support for bodily feedback theories, interoceptive accuracy moderated the relationship between changes in electrodermal activity to proposals and the behavioral rejection of such offers. Larger electrodermal responses to rejected relative to accepted offers predicted greater rejection in those with accurate interoception but were unrelated to rejection in those with poor interoception. Although cardiovascular responses during the offer period were unrelated to rejection rates, greater resting heart rate variability (linked to trait emotion regulation capacity) predicted reduced rejection rates of offers. These findings help clarify individual differences in reactions to perceived unfairness, support previous emotion regulation deficit accounts of rejection behavior, and suggest that the perception and regulation of bodily based emotional biasing signals (“gut feelings”) partly shape financial decision making on the UG.
Decision-making; Embodied cognition; Emotion
Lack of feeling connected and poor social problem solving has been described in suicide attempters. However, cognitive substrates of this apparent social impairment in suicide attempters remain unknown. One possible deficit, the inability to recognize others' complex emotional states has been observed not only in disorders characterized by prominent social deficits (autism-spectrum disorders and frontotemporal dementia) but also in depression and normal aging. This study assessed the relationship between social emotion recognition, problem solving, social functioning, and attempted suicide in late-life depression.
Design, Participants, Measurements
There were 90 participants: 24 older depressed suicide attempters, 38 non-suicidal depressed elders, and 28 comparison subjects with no psychiatric history. We compared performance on the Reading the Mind in the Eyes test and measures of social networks, social support, social problem solving, and chronic interpersonal difficulties in these three groups.
Suicide attempters committed significantly more errors in social emotion recognition and showed poorer global cognitive performance than elders with no psychiatric history. Attempters had restricted social networks: they were less likely to talk to their children, had fewer close friends, and did not engage in volunteer activities, compared to non-suicidal depressed elders and those with no psychiatric history. They also reported a pattern of struggle against others and hostility in relationships, felt a lack of social support, perceived social problems as impossible to resolve, and displayed a careless/ impulsive approach to problems.
Suicide attempts in depressed elders were associated with poor social problem-solving, constricted social networks, and disruptive interpersonal relationships. Impaired social emotion recognition in the suicide attempter group was related to global cognitive decline, thus it is possible that cognitive decline is one of the risk factors for suicide attempt in late-life, interacting with social deficits and psychosocial factors.
Gambling is a widespread recreational activity and requires pitting the values of potential wins and losses against their probability of occurrence. Neuropsychological research showed that betting behavior on laboratory gambling tasks is highly sensitive to focal lesions to the ventromedial prefrontal cortex (vmPFC) and insula. In the current study, we assessed the neural basis of betting choices in healthy participants, using functional magnetic resonance imaging of the Roulette Betting Task. In half of the trials, participants actively chose their bets; in the other half, the computer dictated the bet size. Our results highlight the impact of volitional choice upon gambling-related brain activity: Neural activity in a distributed network – including key structures of the reward circuitry (midbrain, striatum) – was higher during active compared to computer-dictated bet selection. In line with neuropsychological data, the anterior insula and vmPFC were more activated during self-directed bet selection, and responses in these areas were differentially modulated by the odds of winning in the two choice conditions. In addition, responses in the vmPFC and ventral striatum were modulated by the bet size. Convergent with electrophysiological research in macaques, our results further implicate the inferior parietal cortex (IPC) in the processing of the likelihood of potential outcomes: Neural responses in the IPC bilaterally reflected the probability of winning during bet selection. Moreover, the IPC was particularly sensitive to the odds of winning in the active-choice condition, when the processing of this information was required to guide bet selection. Our results indicate an important role of the IPC in human decision-making under risk and help to integrate neuropsychological data of risk-taking following vmPFC and insula damage with models of choice derived from human neuroimaging and monkey electrophysiology.
betting; choice; fMRI; inferior parietal cortex; ventromedial prefrontal cortex; reward
Reduced levels of serotonin (5-HT) within prefrontal cortex (PFC)–amygdala circuits have long been implicated in impulsive aggression. However, whether lowering 5-HT alters the dynamic interplay between the PFC and the amygdala has not been directly tested in humans. It is known that manipulating 5-HT via acute tryptophan depletion (ATD) causes variable effects on brain responses to a variety of emotional stimuli, but it remains unclear whether ATD affects functional connectivity in neural networks involved in processing social signals of aggression (e.g., angry faces).
Thirty healthy individuals were enrolled in a randomized, double-blind, placebo-controlled ATD study. On each treatment, brain responses to angry, sad, and neutral faces were measured with functional magnetic resonance imaging. Two methods (psycho-physiological-interaction in a general linear model and dynamic causal modeling) were used to assess the impact of ATD on the functional connectivity between PFC and amygdala.
Data from 19 subjects were available for the final analyses. A whole-brain psycho-physiological-interaction in a general linear model showed that ATD significantly modulated the connectivity between the amygdala and two PFC regions (ventral anterior cingulate cortex and ventrolateral PFC) when processing angry vs. neutral and angry vs. sad but not sad vs. neutral faces. Dynamic causal modeling corroborated and extended these findings by showing that 5-HT depletion reduced the influence of processing angry vs. neutral faces on circuits within PFC and on PFC–amygdala pathways.
We provide strong support for neurobiological accounts positing that 5-HT significantly influences PFC–amygdala circuits implicated in aggression and other affective behaviors.
5-HT; amygdala; anterior cingulate cortex; effective connectivity; fMRI; violence
Emotions and their psychophysiological correlates are thought to play an important role in decision-making under risk. We used a novel gambling task to measure psychophysiological responses during selection of explicitly presented risky options and feedback processing. Active-choice trials, in which the participant had to select the size of bet, were compared to fixed-bet, no-choice trials. We further tested how the chances of winning and bet size affected choice behavior and psychophysiological arousal. Individual differences in impulsive and risk-taking traits were assessed. The behavioral results showed sensitivity to the choice requirement and to the chances of winning: Participants were faster to make a response on no-choice trials and when the chances of winning were high. In active-choice trials, electrodermal activity (EDA) increased with bet size during both selection and processing of losses. Cardiac responses were sensitive to choice uncertainty: Stronger selection-related heart rate (HR) decelerations were observed in trials with lower chances of winning, particularly on active-choice trials. Finally, betting behavior and psychophysiological responsiveness were moderately correlated with self-reported impulsivity-related traits. In conclusion, we demonstrate that psychophysiological arousal covaries with risk-sensitive decision-making outside of a learning context. Our results further highlight the differential sensitivities of EDA and HR to psychological features of the decision scenario.
Decision-making; Risk; Psychophysiology; Emotion; Personality
Suicide rates are very high in old age, and the contribution of cognitive risk factors remains poorly understood. Suicide may be viewed as an outcome of an altered decision process. We hypothesized that impairment in a component of affective decision-making – reward/punishment-based learning – is associated with attempted suicide in late-life depression. We expected that suicide attempters would discount past reward/punishment history, focusing excessively on the most recent rewards and punishments. Further, we hypothesized that this impairment could be dissociated from executive abilities such as forward planning.
We assessed reward/punishment-based learning using the Probabilistic Reversal Learning task in 65 individuals aged 60 and older: suicide attempters, suicide ideators, non-suicidal depressed elderly, and non-depressed controls. We used a reinforcement learning computational model to decompose reward/punishment processing over time. The Stockings of Cambridge test served as a control measure of executive function.
Suicide attempters but not suicide ideators showed impaired probabilistic reversal learning compared to both non-suicidal depressed elderly and to non-depressed controls, after controlling for effects of education, global cognitive function, and substance use. Model-based analyses revealed that suicide attempters discounted previous history to a higher degree, compared to controls, basing their choice largely on reward/punishment received on the last trial. Groups did not differ in their performance on the Stockings of Cambridge.
Older suicide attempters display impaired reward/punishment-based learning. We propose a hypothesis that older suicide attempters make overly present-focused decisions, ignoring past experiences. Modification of this ‘myopia for the past’ may have therapeutic potential.
suicide; suicide; attempted; cognition; adaptation; psychological; frontal lobe; prefrontal cortex; depressive disorder; aged
Humans react strongly to unfairness, sometimes rejecting inequitable proposals even if this sacrifices personal financial gain. Here we explored whether emotional dispositions - trait tendencies to experience positive or negative feelings – shape the rejection of unfair financial offers. Participants played an Ultimatum Game, where the division of a sum of money is proposed and the player can accept or reject this offer. Individuals high in trait positivity and low in trait negativity rejected more unfair offers. These relationships could not be explained by existing accounts which argue that rejection behaviour results from a failure to regulate negative emotions, or serves to arbitrate social relationships and identity. Instead, the relationship between dispositional affect and rejection behaviour may be underpinned by perceived self worth, with those of a positive disposition believing that they are “worth more than that” and those of a negative disposition resigning themselves to “taking the crumbs from under the table”.
Gambling is a common recreational activity that becomes dysfunctional in a subset of individuals, with DSM ‘pathological gambling’ regarded as the most severe form. During gambling, players experience a range of cognitive distortions that promote an over-estimation of the chances of winning. Near-miss outcomes are thought to fuel these distortions. We observed previously that near-misses recruited overlapping circuitry to monetary wins in a study in healthy volunteers (Clark et al. 2009). The present study sought to extend these observations in regular gamblers and relate brain responses to an index of gambling severity. Twenty regular gamblers, who varied in their involvement from recreational players to probable pathological gamblers, were scanned whilst performing a simplified slot-machine task that delivered occasional monetary wins, as well as near-miss and full-miss non-win outcomes. In the overall group, near-miss outcomes were associated with a significant response in the ventral striatum, which was also recruited by monetary wins. Gambling severity, measured with the South Oaks Gambling Screen, predicted a greater response in the dopaminergic midbrain to near-miss outcomes. This effect survived controlling for clinical co-morbidities that were present in the regular gamblers. Gambling severity did not predict win-related responses in the midbrain or elsewhere. These results demonstrate that near-miss events during gambling recruit reward-related brain circuitry in regular players. An association with gambling severity in the midbrain suggests that near-miss outcomes may enhance dopamine transmission in disordered gambling, which extends neurobiological similarities between pathological gambling and drug addiction.
Gambling; Cognitive; Addiction; Dopamine; Striatum; Midbrain
The concept of ‘depressive realism’, that depression leads to more accurate perception of causal control, has been influential in the field of depression research, but remains controversial. Recent work testing contingency learning has suggested that contextual processing might determine realism-like effects. Serotonin (5-hydroxytryptamine, (5-HT)), which is implicated in the pathophysiology of depression, might also influence contextual processing. Using acute tryptophan depletion (ATD), we tested the hypothesis that dysfunctional serotoninergic neurotransmission influences contingency judgements in dysphoric subjects via an effect on contextual processing.
Materials and methods
We employed a novel contingency learning task to obtain separate measures (ratings) of the causal effect of partcipants’ responses and efficacy of the background context over an outcome. Participants, without a history of depression, completed this task on and off ATD in a double-blind, placebo-controlled, within-subjects design.
As with other work on contingency learning, the effects of ATD were related to baseline mood levels. Although no overall effects of ATD were observed, the subgroup of participants with low Beck depression inventory (BDI) scores showed reduced ratings of contextual control and improved accuracy of contingency judgements under positive contingencies following ATD, compared to placebo. High BDI participants demonstrated low accuracy in contingency judgements, regardless of serotoninergic status.
No effect of ATD on contingency judgements was observed in the group as a whole, but effects were observed in a subgroup of participants with low BDI scores. We discuss these data in light of the context processing hypothesis, and prior research on 5-HT and depressive realism.
Electronic supplementary material
The online version of this article (doi:10.1007/s00213-010-1934-4) contains supplementary material, which is available to authorized users.
Serotonin; Control; Learning; Depression
The neuromodulator serotonin has been implicated in a large number of affective and executive functions, but its precise contribution to motivation remains unclear. One influential hypothesis has implicated serotonin in aversive processing; another has proposed a more general role for serotonin in behavioral inhibition. Since behavioral inhibition is a pre-potent reaction to aversive outcomes, it has been a challenge to reconcile these two accounts. Here, we show that serotonin is critical for punishment-induced inhibition, but not overall motor response inhibition or reporting aversive outcomes. We used acute tryptophan depletion to temporarily lower brain serotonin in healthy human volunteers as they completed a novel task designed to obtain separate measures of motor response inhibition, punishment-induced inhibition, and sensitivity to aversive outcomes. Following a placebo treatment, participants were slower to respond under punishment conditions, compared to reward conditions. Tryptophan depletion abolished this punishment-induced inhibition, without affecting overall motor response inhibition or the ability to adjust response bias in line with punishment contingencies. The magnitude of reduction in punishment-induced inhibition depended on the degree to which tryptophan depletion reduced plasma tryptophan levels. These findings extend and clarify previous research on the role of serotonin in aversive processing and behavioral inhibition, and fit with current theorizing on serotonin's involvement in predicting aversive outcomes.
serotonin; inhibition; aversion; punishment; tryptophan; behavior