José C. Perales

Neuropsychological profiling of impulsivity and compulsivity in cocaine dependent individuals

RationaleResearch on the relative impact of trait impulsivity vs. drug exposure on neuropsychological probes of response inhibition vs. response perseveration has been posited as a valid pathway to explore the transition between impulsivity and compulsivity on psychostimulant dependence.ObjectivesThe objectives of this study are to examine performance differences between cocaine-dependent individuals (CDI) and healthy comparison individuals (HCI) on neuropsychological probes of inhibition and perseveration and to examine the predictive impact of trait impulsivity—a proxy of premorbid vulnerability, and severity of cocaine use—a proxy of drug exposure, on CDI’s performance.MethodsForty-two CDI and 65 HCI were assessed using the UPPS-P Scale (trait impulsivity), the Stroop and go/no-go (inhibition) and revised-strategy application and probabilistic reversal tests (perseveration).ResultsCDI, compared to HCI, have elevated scores on trait impulsivity and perform significantly poorer on inhibition and perseveration, with specific detrimental effects of duration of cocaine use on perseveration.ConclusionsCDI have both inhibition and perseveration deficits; both patterns were broadly indicative of orbitofrontal dysfunction in the context of reinforcement learning. Impulsive personality and cocaine exposure jointly contribute to deficits in response perseveration or compulsivity.

Models of covariation-based causal judgment: A review and synthesis

Causal judgment is assumed to play a central role in prediction, control, and explanation. Here, we consider the function or functions that map contingency information concerning the relationship between a single cue and a single outcome onto causal judgments. We evaluate normative accounts of causal induction and report the findings of an extensive meta-analysis in which we used a cross-validation model-fitting method and carried out a qualitative analysis of experimental trends in order to compare a number of alternative models. The best model to emerge from this competition is one in which judgments are based on the difference between the amount of confirming and disconfirming evidence. A rational justification for the use of this model is proposed.

Impulsivity and executive functions in polysubstance-using rave attenders

ObjectivesRave parties are characterized by high levels of drug use and polysubstance-using patterns that may be especially harmful for psychological and neuropsychological functioning. The aim of this study was to conduct a comprehensive assessment of different aspects of impulsivity and executive functions in a sample of polysubstance-using rave attenders.MethodsWe collected data from two groups: rave attenders (RvA, n = 25) and drug-free healthy comparison individuals (HCI, n = 27). RvA were regular users of cannabis, cocaine, methampethamine, hallucinogens, and alcohol. The assessment protocol included a drug-taking interview, the UPPS-P Impulsive Behavior Scale, the delay-discounting questionnaire and a set of neuropsychological tests taxing different aspects of executive functions: response speed, working memory, reasoning, response inhibition and switching, self-regulation, decision making, and emotion perception.ResultsFor impulsivity measures, RvA had significantly elevated scores on lack of perseverance and positive and negative urgency, but did not differ from controls on lack of premeditation or sensation seeking. For neuropsychological functioning, RvA had significantly poorer performance on indices of analogical reasoning, processing speed, working memory, inhibition/switching errors, and decision making, but performed similar to controls on indices of self-regulation, reversal learning, and emotion processing. Peak and binge alcohol and drug use were positively correlated with positive urgency, and negatively correlated with performance on executive indices.ConclusionRave attenders have selective alterations of impulsive personality and executive functions. These findings can contribute to delineate the neuropsychological profiles that distinguish recreational polysubstance use from substance dependence.

Bright and dark sides of impulsivity: Performance of women with high and low trait impulsivity on neuropsychological tasks

We administered a multidimensional measure of trait impulsivity (the UPPS-P impulsivity scale; Cyders et al., 2007) to a nonclinical sample of 155 individuals and selected 32 participants at the two ends of the trait impulsivity continuum: high (HI, n = 15) and low (LI, n = 17) impulsive women. We further tested these extreme groups on neuropsychological measures of motor impulsivity (go/no-go, d2), delay discounting (Now or Later Questionnaire), reflection impulsivity (Matching Familiar Figures Test), self-regulation (Revised-Strategy Application Test), and decision making (Iowa Gambling Task). High-trait-impulsivity women were found to commit more commission errors in the initial stage of the go/no-go task but also to make fewer omission errors in the d2 test than did low-trait-impulsivity women. Both effects can be accounted for by a lower response criterion in impulsive women. On the other hand, measures of delay discounting, reflection impulsivity, self-regulation, and decision making did not yield significant differences between the two groups. This pattern of results supports the idea that trait impulsivity in healthy women is linked to neurocognitive mechanisms involved in response monitoring and inhibition, but not to mechanisms involved in self-regulation or decision making. These findings temper the assumption that impulsivity is the core cause of dysfunctional risky and/or impulsive behavior in psychopathological or neuropsychological profiles.

Normative and descriptive accounts of the influence of power and contingency on causal judgement

Abstract The power PC theory (Cheng, 1997) is a normative account of causal inference, which predicts that causal judgements are based on the power p of a potential cause, where p is the cause-effect contingency normalized by the base rate of the effect. In three experiments we demonstrate that both cause-effect contingency and effect base-rate independently affect estimates in causal learning tasks. In Experiment 1, causal strength judgements were directly related to power p in a task in which the effect base-rate was manipulated across two positive and two negative contingency conditions. In Experiments 2 and 3 contingency manipulations affected causal estimates in several situations in which power p was held constant, contrary to the power PC theorys predic- tions. This latter effect cannot be explained by participants’ conflation of reliability and causal strength, as Experiment 3 demonstrated independence of causal judgements and confidence. From a descriptive point of view, the data are compatible with Pearces (1987) model, as well as with several other judgement rules, but not with the Rescorla-Wagner (Rescorla & Wagner, 1972) or power PC models.

Emotional and non-emotional pathways to impulsive behavior and addiction

Impulsivity is tightly linked to addiction. However, there are several pathways by means of which impulsive individuals are more prone to become addicts, or to suffer an addiction more intensely and for a longer period. One of those pathways involves an inadequate appraisal or regulation of positive and negative emotions, leading to lack of control over hazardous behaviors, and inappropriate decisions. In the present work, we assessed cocaine-dependent individuals (CDI; n = 20), pathological gamblers (PG; n = 21), and healthy controls (HC; n = 23) in trait impulsivity measures (UPPS-P models dimensions), and decision-making tasks (Go/No-go; delay-discounting task). During the Go/No-go task, electroencephalographic (EEG) activity was recorded, and Go/No-go stimuli-evoked potentials (ERP) were extracted. Theory-driven ERP analyses focused on the No-go > Go difference in the N2 ERP. Our results show that negative urgency is one of the several psychological features that distinguish addicts from HC. Nevertheless, among the dimensions of trait impulsivity, negative urgency is unique at independently covarying with gambling over-pathologization in the PG sample. Cocaine-dependent individuals performed more poorly than gamblers in the Go/No-go task, and showed abnormal Go/No-go stimuli-evoked potentials. The difference between the No-go stimulus-evoked N2, and the Go one was attenuated by severity and intensity of chronic cocaine use. Emotional dimensions of impulsivity, however, did not influence Go/No-go performance.

Inferring Non-Observed Correlations from Causal Scenarios: The Role of Causal Knowledge.

Abstract This work aimed at demonstrating, first, that naive reasoners are able to infer the existence of a relationship between two events that have never been presented together and, second, the sensitivity of such inference to the causal structure of the task. In all experiments, naive participants judged the strength of the causal link between a cue A and an outcome O in a first phase and between a second cue B and the same outcome O in a second phase. In the final test, participants estimated the degree of correlation between the two cues, A and B. Participants perceived the two cues as significantly more highly correlated when they were effects of a common potential cause (Experiment 1a and 2) than when they were potential causes of a common effect (Experiment 1b and 2). This effect of causal directionality on inferred correlation points out the influence of mental models on human causal detection and learning, as proposed by recent theoretical models.

The Brain Network of Expectancy and Uncertainty Processing

Background The Stimulus Preceding Negativity (SPN) is a non-motor slow cortical potential elicited by temporally predictable stimuli, customarily interpreted as a physiological index of expectancy. Its origin would be the brain activity responsible for generating the anticipatory mental representation of an expected upcoming event. The SPN manifests itself as a slow cortical potential with negative slope, growing in amplitude as the stimulus approximates. The uncertainty hypothesis we present here postulates that the SPN is linked to control-related areas in the prefrontal cortex that become more active before the occurrence of an upcoming outcome perceived as uncertain. Methods/Findings We tested the uncertainty hypothesis by using a repeated measures design in a Human Contingency Learning task with two levels of uncertainty. In the high uncertainty condition, the outcome is unpredictable. In the mid uncertainty condition, the outcome can be learnt to be predicted in 75% of the trials. Our experiment shows that the Stimulus Preceding Negativity is larger for probabilistically unpredictable (uncertain) outcomes than for probabilistically predictable ones. sLoreta estimations of the brain activity preceding the outcome suggest that prefrontal and parietal areas can be involved in its generation. Prefrontal sites activation (Anterior Cingulate and Dorsolateral Prefrontal Cortex) seems to be related to the degree of uncertainty. Activation in posterior parietal areas, however, does not correlates with uncertainty. Conclusions/Significance We suggest that the Stimulus Preceding Negativity reflects the attempt to predict the outcome, when posterior brain areas fail to generate a stable expectancy. Uncertainty is thus conceptualized, not just as the absence of learned expectancy, but as a state with psychological and physiological entity.

Heart rate variability and cognitive processing: The autonomic response to task demands

This study investigated variations in heart rate variability (HRV) as a function of cognitive demands. Participants completed an execution condition including the psychomotor vigilance task, a working memory task and a duration discrimination task. The control condition consisted of oddball versions (participants had to detect the rare event) of the tasks from the execution condition, designed to control for the effect of the task parameters (stimulus duration and stimulus rate) on HRV. The NASA-TLX questionnaire was used as a subjective measure of cognitive workload across tasks and conditions. Three major findings emerged from this study. First, HRV varied as a function of task demands (with the lowest values in the working memory task). Second, and crucially, we found similar HRV values when comparing each of the tasks with its oddball control equivalent, and a significant decrement in HRV as a function of time-on-task. Finally, the NASA-TLX results showed larger cognitive workload in the execution condition than in the oddball control condition, and scores variations as a function of task. Taken together, our results suggest that HRV is highly sensitive to overall demands of sustained attention over and above the influence of other cognitive processes suggested by previous literature. In addition, our study highlights a potential dissociation between objective and subjective measures of mental workload, with important implications in applied settings.

Validation of a short Spanish version of the UPPS¿P impulsive behaviour scale

Aim Impulsivity is a multifaceted construct that has a prominent role in psychiatry and especially in addiction. The objective of the current study is to develop and validate a Spanish version of the short UPPS-P impulsive behavior scale1, which assesses five distinct impulsivity traits (positive urgency, negative urgency, lack of premeditation, lack of perseverance, and sensation seeking). Material and methods One hundred and eighty-nine participants were included in the study. Confirmatory factor analyses supported the five-factor model of the original scale. Results The results indicated good internal reliability. External validity was supported by specific relationships with a scale assessing emotion regulation strategies. Conclusion Accordingly, the short Spanish version of the UPPS-P scale presents good psychometric properties and may be considered a promising instrument for both research and clinical practice.