Opposite effects of cannabis and cocaine on performance monitoring

L-DOPA and oxytocin influence the neural correlates of performance monitoring for self and others

RATIONALE

The ability to monitor the consequences of our actions for others is imperative for flexible and adaptive behavior, and allows us to act in a (pro)social manner. Yet, little is known about the neurochemical mechanisms underlying alterations in (pro)social performance monitoring.

OBJECTIVE

The aim of this functional magnetic resonance imaging (fMRI) study was to improve our understanding of the role of dopamine and oxytocin and their potential overlap in the neural mechanisms underlying performance monitoring for own versus others' outcomes.

METHOD

Using a double-blind placebo-controlled cross-over design, 30 healthy male volunteers were administered oxytocin (24 international units), the dopamine precursor L-DOPA (100 mg + 25 mg carbidopa), or placebo in three sessions. Participants performed a computerized cannon shooting game in two recipient conditions where mistakes resulted in negative monetary consequences for (1) oneself or (2) an anonymous other participant.

RESULTS

Results indicated reduced error-correct differentiation in the ventral striatum after L-DOPA compared to placebo, independent of recipient. Hence, pharmacological manipulation of dopamine via L-DOPA modulated performance-monitoring activity in a brain region associated with reward prediction and processing in a domain-general manner. In contrast, oxytocin modulated the BOLD response in a recipient-specific manner, such that it specifically enhanced activity for errors that affected the other in the pregenual anterior cingulate cortex (pgACC), a region previously implicated in the processing of social rewards and prediction errors. Behaviorally, we also found reduced target sizes-indicative of better performance-after oxytocin, regardless of recipient. Moreover, after oxytocin lower target sizes specifically predicted higher pgACC activity when performing for others.

CONCLUSIONS

These different behavioral and neural patterns after oxytocin compared to L-DOPA administration highlight a divergent role of each neurochemical in modulating the neural mechanisms underlying social performance monitoring.

Dopaminergic and norepinephrinergic modulation of endogenous event-related potentials: A systematic review and meta-analysis

Event-related potentials (ERPs) represent the cortical processing of sensory, motor or cognitive functions invoked by particular events or stimuli. A current theory posits that the catecholaminergic neurotransmitters dopamine (DA) and norepinephrine (NE) modulate a number of endogenous ERPs during various cognitive processes. This manuscript aims to evaluate a leading neurotransmitter hypothesis with a systematic overview and meta-analysis of pharmacologic DA and NE manipulation of specific ERPs in healthy subjects during executive function. Specifically, the frontally-distributed P3a, N2, and Ne/ERN (or error-related negativity) are supposedly modulated primarily by DA, whereas the parietally-distributed P3b is thought to be modulated by NE. Based on preceding research, we refer to this distinction between frontally-distributed DA-sensitive and parietally-distributed NE-sensitive ERP components as the Extended Neurobiological Polich (ENP) hypothesis. Our systematic review and meta-analysis indicate that this distinction is too simplistic and many factors interact with DA and NE to influence these specific ERPs. These may include genetic factors, the specific cognitive processes engaged, or elements of study design, i.e. session or sequence effects or data-analysis strategies.

l-DOPA and oxytocin influence the neurocomputational mechanisms of self-benefitting and prosocial reinforcement learning

Humans learn through reinforcement, particularly when outcomes are unexpected. Recent research suggests similar mechanisms drive how we learn to benefit other people, that is, how we learn to be prosocial. Yet the neurochemical mechanisms underlying such prosocial computations remain poorly understood. Here, we investigated whether pharmacological manipulation of oxytocin and dopamine influence the neurocomputational mechanisms underlying self-benefitting and prosocial reinforcement learning. Using a double-blind placebo-controlled cross-over design, we administered intranasal oxytocin (24 IU), dopamine precursor l-DOPA (100 mg + 25 mg carbidopa), or placebo over three sessions. Participants performed a probabilistic reinforcement learning task with potential rewards for themselves, another participant, or no one, during functional magnetic resonance imaging. Computational models of reinforcement learning were used to calculate prediction errors (PEs) and learning rates. Participants behavior was best explained by a model with different learning rates for each recipient, but these were unaffected by either drug. On the neural level, however, both drugs blunted PE signaling in the ventral striatum and led to negative signaling of PEs in the anterior mid-cingulate cortex, dorsolateral prefrontal cortex, inferior parietal gyrus, and precentral gyrus, compared to placebo, and regardless of recipient. Oxytocin (versus placebo) administration was additionally associated with opposing tracking of self-benefitting versus prosocial PEs in dorsal anterior cingulate cortex, insula and superior temporal gyrus. These findings suggest that both l-DOPA and oxytocin induce a context-independent shift from positive towards negative tracking of PEs during learning. Moreover, oxytocin may have opposing effects on PE signaling when learning to benefit oneself versus another.

Tasting rewards. Effects of orosensory sweet signals on human error processing

Human research has shown interactions between rewards and cognitive control. In animal models of affective neuroscience, reward administration typically involves administering orosensory sugar signals (OSS) during caloric-deprived states. We adopted this procedure to investigate neurophysiological mechanisms of reward-cognitive control interactions in humans. We predicted that OSS would affect neurophysiological and behavioral indices of error processing oppositely, depending on the relative weight of the OSS-induced 'wanting' and 'liking' components of reward. We, therefore, conducted a double-blind, non-nutritive sweetener-controlled study with a within-subject design. Fasted (16 hr) participants (N = 61) performed a modified Flanker task to assess neurophysiological (error-related negativity [N_e/ERN]) and behavioral (post-error adaptations) measures of error processing. Non-contingent to task performance, we repeatedly administered either a sugar (glucose) or non-nutritive sweetener (aspartame) solution, which had to be expulsed after short oral stimulation to prevent post-oral effects. Consistent with our hypothesis on how 'liking' would affect N_e/ERN amplitude, we found the latter to be decreased for sugar compared to aspartame. Unexpectedly, we found post-error accuracy, instead of post-error slowing, to be reduced by sugar relative to aspartame. Our findings suggest that OSS may interact with error processing through the 'liking' component of rewards. Adopting our reward-induction procedure (i.e. administering OSS in a state of high reward sensitivity [i.e. fasting], non-contingent to task performance) might help future research investigating the neural underpinnings of reward-cognitive control interactions in humans.

To What Extent Does Illicit Drug Use Predispose to Facial Injury? An Institutional Investigation for an Emergent Problem

Study Design

There are potential substantive linkages between illicit drug use and the occurrence of injury.

Objective

The purpose of our study was to determine the prevalence, class of illicit drugs abused, and demographics in relation to a cohort of patients who sustained facial injury.

Methods

The authors undertook a retrospective observational study of a prospectively accessioned cohort of patients who had sustained a facial injury and presented to the John Hunter Hospital (Newcastle, NSW, Australia). The primary predictor variable was the presentation of a facial injury and the secondary outcome variables included illicit drug use, alcohol use, and socioeconomic factors. The study was carried out over a 12-month period. A descriptive analysis was undertaken on the assembled data.

Results

Of the 465 patient medical records that were accessed for the study, 348 were male and 117 were female. Their average age was 42.6 years: 5.8% (n = 27) were under the influence of illicit drugs at the time of their presentation and 13.1% (n = 61) admitted to an intercurrent illicit drug habit. Those who were under the combined influence of alcohol and drugs comprised of 2.8% (n = 13).

Conclusions

Our study found that illicit drug use plays a small, but nonetheless, demonstrable role in the presentation of maxillofacial trauma patients to an urban level I trauma center. Illicit drug users are an emergent sociodemographic group of patients who can sustain facial trauma and their presentation needs to be appropriately considered, assessed, and managed collectively.

Enhanced error-related brain activations for mistakes that harm others: ERP evidence from a novel social performance-monitoring paradigm

Our mistakes often have negative consequences for ourselves, but may also harm the people around us. Continuous monitoring of our performance is therefore crucial for both our own and others' well-being. Here, we investigated how modulations in responsibility for other's harm affects electrophysiological correlates of performance-monitoring, viz. the error-related negativity (ERN) and error positivity (Pe). Healthy participants (N = 27) performed a novel social performance-monitoring paradigm in two responsibility contexts. Mistakes made in the harmful context resulted in a negative consequence for a co-actor, i.e., hearing a loud aversive sound, while errors in the non-harmful context were followed by a soft non-aversive sound. Although participants themselves did not receive auditory feedback in either context, they did experience harmful mistakes as more distressing and reported higher effort to perform well in the harmful context. ERN amplitudes were enhanced for harmful compared to non-harmful mistakes. Pe amplitudes were unaffected. The present study shows that performing in a potentially harmful social context amplifies early automatic performance-monitoring processes and increases the impact of the resulting harmful mistakes. These outcomes not only further our theoretical knowledge of social performance monitoring, but also demonstrate a novel and useful paradigm to investigate aberrant responsibility attitudes in various clinical populations.

Intoxicated aggression: Do alcohol and stimulants cause dose-related aggression? A review

RATIONALE

Violence and drug use are significant public health challenges that are strongly linked. It is known that alcohol plays a major role in the causation of unnatural deaths and that stimulants like cocaine and amphetamine are often implicated in aggressive acts or violence. However, a clear causal relationship between these substances and aggression, and more specifically a blood concentration threshold at which intoxicated aggression emerges is lacking. In case of a crime and subsequent law enforcement, knowledge about dose-response relationships could be of pivotal importance when evaluating the role of alcohol and drugs in aggressive offences.

AIMS

The present review aimed to determine whether there is a causal relation between intoxication with these psychoactive substances and aggression, and to define blood concentration thresholds above which these substances elicit aggression.

METHODS

Empirical articles published between 2013 and 2017 and review papers containing the predefined search strings were identified through searches in the PubMed and Embase databases and additional reference list searches. The complete search query yielded 1578 publications. Initially all articles were manually screened by title and abstract. Articles with irrelevant titles, given the selected search terms and review aims were discarded. Remaining articles were carefully studied and those that did not comply with the main objectives of this review were discarded. At the end of this process, 167 titles were found eligible for review.

FINDINGS AND CONCLUSION

While placebo-controlled experimental studies clearly showed a causal link between alcohol and aggression, it is evident that such a link has not yet been established for cocaine and amphetamines. In case of alcohol, it is clear that there are various individual and contextual factors that may contribute to the occurrence of an aggressive act during intoxication. A clear threshold blood alcohol concentration has not been defined yet for alcohol, but a statistically significant increase of aggression has been demonstrated at a dose of 0.75 g/kg and higher. Future studies into intoxicated aggression should include multiple doses of alcohol and stimulants and take into account individual and contextual factors.

Dopaminergic and noradrenergic manipulation of anticipatory reward and probability event-related potentials

Predicting what will happen in the future in terms of potential reward is essential in daily life. The aim of the current study was to investigate the neurotransmitter systems involved in the anticipation of reward value and probability. We hypothesized that dopaminergic and noradrenergic antagonism would affect anticipation of reward value and probability, respectively. Twenty-three healthy participants were included in a haloperidol (2 mg) × clonidine (0.150 mg) × placebo cross-over design and subjected to a Go/NoGo experimental task during which cues signaled the probability of subsequent target appearance. Reward value (amount of money that could be won for correct and fast responding to the target) as well as probability of target appearance was orthogonally manipulated across four task blocks. Cue-elicited EEG event-related potentials were recorded to assess anticipation of value and probability, respectively. The processing of reward value was affected by dopaminergic antagonism (haloperidol), as evidenced by reduction of the reward-related positivity and P300 to reward cues. This reduction was specifically significant for subjects with high baseline dopamine levels for the P300 and most pronounced for these subjects for the reward-related positivity. In contrast, the processing of reward probability was affected by noradrenergic antagonism (clonidine). In addition, both drugs reduced overall performance (omission rate, response speed variability). We conclude that at least anticipation of reward value and probability, respectively, is specifically affected by dopaminergic versus noradrenergic antagonism.

Processing of performance errors predicts memory formation: Enhanced feedback-related negativities for corrected versus repeated errors in an associative learning paradigm

Learning from errors or negative feedback is crucial for adaptive behavior. FMRI studies have demonstrated enhanced anterior cingulate cortex activity for errors that were later corrected versus repeated errors even when a substantial delay between the error and the opportunity to correct was introduced. We aimed at identifying the electrophysiological correlates of these processes by investigating the feedback‐related negativity (FRN) and stimulus‐locked P3. Participants had to learn and recall the location of 2‐digit targets over consecutive rounds. Feedback was provided in two steps, first a color change indicated a correct or incorrect response (feedback phase) followed by presentation of the correct digit information (re‐encoding phase). Behaviorally, participants improved performance from the first to the third round. FRN amplitudes time‐locked to feedback were enhanced for corrected compared to repeated errors. The P3 in response to re‐encoding did not differ between the two error types. The finding that FRN amplitudes positively predicted memory performance is consistent with the idea that the FRN reflects prediction errors and the need for enhanced cognitive control. Interestingly, this happens early during feedback processing and not at a later time point when re‐encoding of correct information takes place. The prediction error signal reflected in the FRN is usually elicited by performance errors, but may thus also play a role in preparing/optimizing the system for memory formation. This supports the existence of a close link between action control and memory processes even when there is a substantial delay between error feedback and the opportunity to correct the error.

Meta-analysis of aberrant post-error slowing in substance use disorder: implications for behavioral adaptation and self-control

Individual with substance use disorders have well-recognized impairments in cognitive control, including in behavioral adaptation after mistakes. One way in which this impairment manifests is via diminished post-error slowing, the increase in reaction time following a task-related error that is posited to reflect cautionary or corrective behavior. Yet, in the substance use disorder literature, findings with regard to post-error slowing have been inconsistent, and thus could benefit from quantitative integration. Here, we conducted a meta-analysis of case-control studies examining post-error slowing in addiction. Twelve studies with 15 unique comparisons were identified, comprising 567 substance users and 384 healthy controls across three broad types of inhibitory control paradigms (go-no/go, conflict resolution, and stop signal tasks, respectively). Results of the random-effects meta-analysis revealed a moderate group difference across all studies (Cohen's d = 0.31), such that the individuals with substance use disorder had diminished post-error slowing compared with controls. Despite this omnibus effect, there was also large variability in the magnitude of the effects, explained in part by differences between studies in task complexity. These findings suggest that post-error slowing may serve as a promising and easy-to-implement measure of cognitive control impairment in substance use disorder, with potential links to aberrant brain function in cognitive control areas such as the anterior cingulate cortex.

Let's Open the Decision-Making Umbrella: A Framework for Conceptualizing and Assessing Features of Impaired Decision Making in Addiction

Decision-making impairments play a pivotal role in the emergence and maintenance of addictive disorders. However, a sound conceptualization of decision making as an umbrella construct, encompassing its cognitive, affective, motivational, and physiological subcomponents, is still lacking. This prevents an efficient evaluation of the heterogeneity of decision-making impairments and the development of tailored treatment. This paper thus unfolds the various processes involved in decision making by adopting a critical approach of prominent dual- or triadic-process models, which postulate that decision making is influenced by the interplay of impulsive-automatic, reflective-controlled, and interoceptive processes. Our approach also focuses on social cognition processes, which play a crucial role in decision making and addictive disorders but were largely ignored in previous dual- or triadic-process models. We propose here a theoretical framework in which a range of coordinated processes are first identified on the basis of their theoretical and clinical relevance. Each selected process is then defined before reviewing available results underlining its role in addictive disorders (i.e., substance use, gambling, and gaming disorders). Laboratory tasks for measuring each process are also proposed, initiating a preliminary process-based decision-making assessment battery. This original approach may offer an especially informative view of the constitutive features of decision-making impairments in addiction. As prior research has implicated these features as risk factors for the development and maintenance of addictive disorders, our processual approach sets the scene for novel and transdiagnostic experimental and applied research avenues.

Electrophysiological correlates of oxytocin-induced enhancement of social performance monitoring

Altered performance monitoring has been demonstrated after administration of different pharmacological compounds and in various clinical populations, such as excessive neurophysiological responses to mistakes in anxiety disorders. Here, a novel social pharmacological approach was applied to investigate whether oxytocin administration (24 IU) enhances performance monitoring for errors that have negative consequences for another individual, so-called social mistakes. Healthy male volunteers (N = 24) participated in a placebo-controlled crossover design. EEG measures were obtained while pairs of participants performed a speeded choice reaction-time task in an individual and social context. Following oxytocin administration, error-related negativity amplitudes were increased for social compared with individual mistakes. This increase was not found in the placebo condition. No effects of oxytocin were present in the individual context. The current study shows that oxytocin enhances performance monitoring specifically for social mistakes. This outcome is in line with a presumed role for oxytocin in salience attribution to social cues and underlines its context-dependency. Combining these processes may thus open up new research avenues and advance our understanding of individual differences in performance monitoring and oxytocin responses from a social neurocognitive, pharmacological and clinical perspective.

Event-related potentials reflect impaired temporal interval learning following haloperidol administration

BACKGROUND

Signals carried by the mesencephalic dopamine system and conveyed to anterior cingulate cortex are critically implicated in probabilistic reward learning and performance monitoring. A common evaluative mechanism purportedly subserves both functions, giving rise to homologous medial frontal negativities in feedback- and response-locked event-related brain potentials (the feedback-related negativity (FRN) and the error-related negativity (ERN), respectively), reflecting dopamine-dependent prediction error signals to unexpectedly negative events. Consistent with this model, the dopamine receptor antagonist, haloperidol, attenuates the ERN, but effects on FRN have not yet been evaluated.

METHODS

ERN and FRN were recorded during a temporal interval learning task (TILT) following randomized, double-blind administration of haloperidol (3 mg; n = 18), diphenhydramine (an active control for haloperidol; 25 mg; n = 20), or placebo (n = 21) to healthy controls. Centroparietal positivities, the Pe and feedback-locked P300, were also measured and correlations between ERP measures and behavioral indices of learning, overall accuracy, and post-error compensatory behavior were evaluated. We hypothesized that haloperidol would reduce ERN and FRN, but that ERN would uniquely track automatic, error-related performance adjustments, while FRN would be associated with learning and overall accuracy.

RESULTS

As predicted, ERN was reduced by haloperidol and in those exhibiting less adaptive post-error performance; however, these effects were limited to ERNs following fast timing errors. In contrast, the FRN was not affected by drug condition, although increased FRN amplitude was associated with improved accuracy. Significant drug effects on centroparietal positivities were also absent.

CONCLUSIONS

Our results support a functional and neurobiological dissociation between the ERN and FRN.