Increased impulsivity and alterations in reward sensitivity co-occur in many psychiatric disorders. Moreover, individuals reporting more impulsive traits are less efficient in learning stimulus-reward associations. This suggests that impulsivity and reward sensitivity may be linked, consistent with evidence that the orbital frontal cortex (OFC) is implicated in both processes. This study examined the relationship between impulsive traits, assessed by the Barratt Impulsiveness Scale (BIS) and the Eysenck (EIQ), and performance on three behavioral tasks that measure impulsivity and reward sensitivity. The tasks included a Conditioned Pattern Preference (CPP) task, which measures the preference for abstract visual cues as an index of implicit emotional learning, a Probabilistic Reversal Learning (PRL) task that assessed the ability to alter behaviour when reward contingencies change and an Emotional Stroop task which assessed attentional control in response to emotionally salient stimuli. This study provided novel information on the relationship between processes that mediate impulsivity and reward sensitivity. In brief, subjects that were considered to have some explicit knowledge of experimental conditions showed a higher preference formation for the pattern paired with the reward on 90% of the conditioning trials. Although there was no overall effect of impulsivity, the medium impulsive group displayed the strongest preference formation (highest score for the 90% pattern and lowest score for the 10% pattern) compared to the low and high groups. Furthermore, there was an overall effect of Word Category in that participants made more errors for the emotional words (positive and negative) than the neutral words. There was no overall effect of Impulsivity on Stroop performance in this sample. Finally, for the PRL task more participants in the high impulsive group did not meet criterion for the Acquisition stage while more low impulsive subjects did not meet reversal criterion. Furthermore, high impulsive subjects made more overall errors in the Acquisition stage but not Reversal stage. In brief, low and high impulsive subjects performed sub-optimally on the CPP and PRL tasks but not on the Stroop task. This pattern reflects an inverted-U shaped relationship of the effects of impulsivity on associative learning. / Thesis (Master, Psychology) -- Queen's University, 2010-02-05 13:33:27.076

Nonsuicidal self-injury (NSSI), the deliberate self-destruction of one’s own body tissue engaged in without associated suicidal intent, is a prevalent behavior among adolescents and young adults. The current study examined whether one aspect of cognitive control, inhibitory control in response to negative emotional stimuli, is associated with repetitive engagement in NSSI. It further sought to examine whether sleep deficiency/irregularity, stress, and reward sensitivity moderate this relationship. A multi-method approach (self-report, behavioral measures, actigraphy) was employed to sensitively probe these relationships among 114 late adolescents with and without a history of repetitive NSSI. Findings suggested no relationship between inhibitory control in response to negative emotional stimuli and NSSI, as measured by a behavioral measure, but a significant positive relationship as measured by self-report. Stress and sleep irregularity, but not sleep deficiency or reward sensitivity, were associated with NSSI group status. Interaction analyses suggested that sleep irregularity and stress moderated the relationship between inhibitory control in response to negative emotional stimuli and NSSI. Results are discussed in terms of conceptual and clinical implications. Findings highlight the necessity of examining the temporal dynamics between the study’s constructs and NSSI by employing an ecologically valid approach. / Psychology

Social anxiety disorder (SAD) is a debilitating disorder marked by persistent fear of one or more social or performance situations that is associated with poor daily functioning in various areas of life. Most empirically-supported interventions for SAD are based on cognitive behavioral models that focus largely on reducing negative emotions. However, these approaches produce only modest rates of remission, suggesting that core components of SAD may not be sufficiently targeted by current treatments. Recent theoretical models have suggested that diminished sensitivity to reward may be a specific factor related to low positive affect (PA) and by extension social anxiety, yet no research has systematically examined this relationship. Additionally, working memory has been found to activate dopamine synthesis related to reward, however this relation has not been demonstrated in social anxiety. Accordingly, research proposed here sought to characterize PA and working memory, and determine whether reward sensitivity is altered in a self-reported socially anxious sample of 59 young adults. We hypothesized that social anxiety symptomatology would be inversely correlated with the magnitude of reward sensitivity as measured using the Reward Bias Task (RBT). Results within the full sample did not support our hypothesis; however, an unexpected relationship between PA and working memory emerged. Once using conservative data quality procedures, results indicated that the online version of the reward bias task demonstrated promising relationships with depression and working memory. Additionally, after controlling for depression, the restricted sample demonstrated a relationship between reward bias mean and working memory, and SPIN and diminished PA. / M.S. / Social anxiety disorder is related to poor daily functioning in various areas of life, such as school, work, and social functioning, and also increases the risk for depression and substance abuse. Over half of patients with the disorder remain symptomatic after treatment. Low levels of positive emotionality, or positive affect (PA), has been associated with social anxiety. Additionally, individuals with social anxiety are thought to have less reward seeking behaviors, which may be related to their working memory abilities. Our study looked at PA, reward and working memory in a sample of 59 socially anxious young adults. Within our full sample, we found that PA and working memory were related, such that participants with higher levels of PA also had better working memory abilities. Within our restricted sample of 17 socially anxious adults we found that reward seeking behaviors were related to depression and working memory. Additionally, after accounting for depression, reward seeking and working memory were related, and social anxiety symptoms and PA were related.

Feedback-based learning is a process in which decisions are made based on the previous feedback. This learning process is influenced by acute stress. However, different laboratory stressors elicit different physiological response patterns, which may influence feedback processing differently. Moreover, individual differences in stress reactivity may be associated with reward sensitivity. Therefore, the present study investigated the effects of psychosocial and physical stress on feedback-based learning. The relationship between stress reactivity and reward sensitivity was also examined. Ninety-two college-aged subjects were assigned into the mental arithmetic (MA) task or the cold pressor task (CPT) group. All subjects performed a feedback-based learning task prior to and after the stressor. Cardiovascular reactions, stress experiences, and learning outcomes were recorded during tasks. Trait differences in behavioral inhibition and activation (BIS/BAS) were also measured. Results indicated different patterns of cardiovascular reactions to the MA and CPT. Learning outcomes were differentially influenced by the MA and CPT. Moreover, subjective stress scores were negatively correlated with the learning rate in the pre-stress learning task. Additionally, BAS Drive subscale score was related to the processing of positive feedback. The results suggested that physical and psychosocial stress influence learning through distinct neural mechanisms and psychological processes. Motivational processes underlie the relationship between stress reactivity and reward sensitivity. This study extended research on stress and learning, and the findings have applied implications in various areas. / Ph. D. / People learn to make decisions based on their previous experiences. These processes are influenced by a wide range of non-learning factors, such as stress. Different types of stress may influence learning and decision-making differently. The present study examined the effects of physical and psychosocial stress on a feedback-based learning task. A cold pressor task and a mental arithmetic task were used to induce physical and psychosocial stress, respectively. The parameters that reflect learning processes and outcomes were calculated by using the standard action-value learning algorithm. Physiological measures, including electrocardiograph, respiration, and blood pressure, were recorded. Individual differences in motivation were measured by self-report questionnaires. The results showed that 1) physical and psychosocial stress induced different patterns of stress response; 2) the effects of the two types of stress on learning parameters and performance were different; 3) blood pressure was related to the effect of stress on learning; 4) individual differences in motivation was also related to feedback-based learning. Overall, the present results demonstrated the differences between the effects of the two types of stress, and contribute to the literature of learning and stress. These findings will guide future studies in this area and have applied implications in various areas.

Chronic nicotine use has been linked to increased sensitivity to nondrug rewards as well as improvement in mood among individuals with depression, and these effects have been hypothesized to be mediated through alternations in striatal dopamine activity. Similarly, chronic nicotine use is hypothesized to influence the mechanisms by which healthy and depressed individuals learn about rewards in their environment. However, the specific behavioral and neural mechanisms by which nicotine influences the learning process is poorly understood. Here, we use a probabilistic learning task, functional magnetic resonance imaging and neurocomputational analyses, to show that chronic smoking is associated with higher reward sensitivity, along with lower learning rate and striatal prediction error signal. Further, we show that these effects do not differ between individuals with and without major depressive disorder (MDD). In addition, a negative correlation between reward sensitivity and striatal prediction error signal was found among smokers, consistent with the suggestion that enhanced tonic dopamine associated with increased reward sensitivity leads to an attenuation of phasic dopamine activity necessary for updating of reward value during learning. / Master of Science / Nicotine use has been associated with increased sensitivity to nondrug rewards and improvement in mood among individuals with depression, and these effects maybe attributed to neural activity in the striatum, a brain region related to reward perception and learning. Chronic nicotine may also influence reward learning in healthy and depressed individuals but this influence is poorly understood. Therefore, we use a computerized learning task to measure participants’ behavioral performance, functional magnetic resonance imaging to collect their brain activity data and neurocomputational analyses to examine their learning process. We showthat, compared to nonsmokers, chronic smokers perceive rewards as more rewarding (higher reward sensitivity), they learn the value of a reward slower (lower learningrate) and the neural activity in their striatum is weaker in the learning process. Moreover, we show that these effects do not differ between individuals with and without depression.

The study’s objective was to assess whether resting-state regional functional connectivity and current source density (CSD) measured during smoking abstinence predict smoking progression across 18 months, depressive traits, and nicotine-enhanced reward sensitivity (NERS) in young light-nicotine (NIC) smokers using low-resolution brain electromagnetic tomography analysis (LORETA). A secondary goal was to assess whether depressive traits moderate the ability of connectivity and regional CSD to predict NERS. Brain regions of interest (ROIs) hypothesized to predict smoking progression, NERS, and depressive traits include structures with high-density nicotinic acetylcholine receptors (nAChRs) and reward-related areas. A total of N=108, 14-hour NIC-deprived young (age 18-24) light (5-35 NIC uses/week) smokers underwent electroencephalogram (EEG) recording while at rest (i.e., viewed a white crosshair on a black background) for 8 minutes then completed the PRT, an assessment of reward sensitivity, after smoking a placebo (0.05 mg NIC) and NIC (0.8 mg NIC) cigarette using a within-subjects design allowing for the assessment of NIC-induced changes in reward sensitivity. All EEG power and LORETA activity bands underwent regression analysis to discover if EEG-assessed brain activity can predict smoking progression, depressive traits, NERS, and their potential interaction. Localized brain regions include 1) reward-related structures, 2) depressive trait-related structures, and 3) large-scale neural (e.g., salience network (SN), default mode network (DMN), executive control network (ECN)) and substance use disorder networks (e.g., orbital frontal cortex (OFC), insula, dorsal lateral prefrontal cortex (dlPFC) anterior cingulate cortex (ACC)). Weaker resting-state connectivity (rsC) between the insula and ACC (i.e., SN) predicted greater smoking progression at 18 months (theta1 and theta2) and greater depressive traits (delta and theta1), while greater rsC within the SN predicted greater NERS (alpha2 and beta 2/3[23.19 – 25.14 Hz]). Greater NERS was also predicted by greater alpha2 connectivity between the 1) ACC and posterior cingulate cortex (PCC) and 2) ACC and left dlPFC. Greater depressive traits were also predicted by 1) weaker delta and theta2 connectivity between the bilateral insula, 2) weaker delta, theta1, and theta2 between the insula and dlPFC, 3) weaker delta and theta1 between the insula and subgenual cortex, 4) greater theta2 in the right vs. left default mode, and 5) greater delta (2.44 – 3.41 Hz) in the left vs. right default mode network. Both greater depressive traits and greater NERS were predicted by weaker 1) theta2/alpha1 (6.59 – 9.52 Hz) between the insula and dlPFC and 2) alpha1 (7.5 – 9.5 Hz) between the left orbital frontal cortex and right dlPFC. These findings provide the first evidence that differences in EEG-assessed brain connectivity in young light smokers are associated with nicotine-enhanced reward sensitivity, depressive traits, and smoking progression. Notably, weaker low-frequency rsC within the salience network predicted depressive traits and smoking progression, while greater high-frequency rsC predicted greater nicotine-enhanced reward sensitivity. These findings suggest that salience network rsC and drug-enhanced reward sensitivity may be useful tools and potential endophenotypes for reward sensitivity and drug-dependence research.

Literature Review: Anhedonia, the loss of interest or pleasure in usually pleasurable activities, is a core symptom of depression and is associated with a reduction in positive affect (PA). Repetitive negative thought (RNT) is implicated in the development and maintenance of psychiatric disorders. It has been hypothesised that RNT causally contributes to anhedonia. The aim of this review was to explore this relationship to answer two questions: Is there a relationship between RNT and anhedonia? Does RNT causally contribute to anhedonia? Review inclusion criteria were: studies using standardised measures to report a relationship between RNT and anhedonia or reduced PA. Results suggest that cross-sectional and longitudinal studies identify a relationship between RNT and anhedonia. Preliminary evidence from experimental studies shows that RNT causally contributes to anhedonia. Limitations within the field are that anhedonia is rarely measured directly or behaviourally. Future research is warranted to explore the relationship between RNT and anhedonia with a particular focus on direct and behavioural measures of anhedonia. Empirical Paper: It is hypothesised that repetitive negative thought (RNT) causally contributes to anhedonia. There is cross-sectional and longitudinal evidence of this relationship, but it has not previously been investigated directly using experimental methods. In the present study, student participants were randomly assigned to an unresolved goal (RNT) manipulation (n = 43) or resolved goal (control) manipulation (n =41) prior to completing a reward sensitivity task. This task has been reliably found to train a response bias towards the stimuli that is differentially positively reinforced, with both depression and self-reported anhedonia associated with a reduced response bias. The unresolved goal versus resolved goal manipulation was effective, with the unresolved condition producing significantly higher levels of RNT during the reward sensitivity task relative to the resolved condition. Inconsistent with study predictions, there was no significant difference between the conditions on response bias, although there were trend findings, which tentatively suggest that RNT may influence anhedonia. Potential accounts for the null findings and future research are discussed.

Alterations in the dopaminergic system have been implicated in both animal and human obesity. However, to date, a comprehensive model on the nature and functional relevance of this relationship is missing. In particular, human data remain equivocal in that seemingly inconsistent reports exist of positive, negative or even no relationships between dopamine D2/D3 receptor availability in the striatum and measures of obesity. Further, data on receptor availability have been commonly interpreted as reflecting receptor density, despite the possibility of an alternative interpretation, namely alterations in the basal levels of endogenous dopaminergic tone. Here, we provide a unifying framework that is able to explain the seemingly contradictory findings and offer an alternative and novel perspective on existing data. In particular, we suggest (i) a quadratic relationship between alterations in the dopaminergic system and degree of obesity, and (ii) that the observed alterations are driven by shifts in the balance between general dopaminergic tone and phasic dopaminergic signalling. The proposed model consistently integrates human data on molecular and behavioural characteristics of overweight and obesity. Further, the model provides a mechanistic framework accounting not only for the consistent observation of altered (food) reward–responsivity but also for the differences in reinforcement learning, decision-making behaviour and cognitive performance associated with measures of obesity.

Based on existing theories of personality and socio-emotional functioning (e.g. Clark, 2005; Lynch, Hempel & Clark, in press) a new model is proposed and tested. The model hypothesises that (i) temperament (reward and threat sensitivity) and childhood invalidation predict problems with interpersonal functioning, (ii) this effect is mediated by self-regulatory capacity; where self-regulatory capacity comprises self-control (ranging from emotional over-control to emotional under-control) and flexible control and (iii) self-regulatory capacity itself has a quadratic relationship with interpersonal functioning. A UK community sample (n= 512) completed a self-report survey, measuring each of the aforementioned latent variables. Structural equation modelling (SEM) was used to determine the goodness-of-fit of this and variations of this model. SEM identified that a non-mediation model provided the best fit (χ²=49.403, p< 0.001; CFI=0.98; RMSEA=0.056). Good-fit was obtained for a model including flexible control as a partial mediator (χ²=269.06, p< 0.001; CFI=0.956; RMSEA=0.081) and adequate-fit for a model including over-control as a partial mediator (χ²= 91.744, p < 0.001, CFI=0.932; RMSEA= 0.096). Correlation analyses suggested that over-control and under-control correlated positively with interpersonal problems. Results from SEM provided promising initial evidence for the mediating role of self-regulatory capacity, particularly for the flexible control component. Correlation analyses provided support for the non-linear relationship between self-regulatory capacity and interpersonal functioning, whereby extreme over-control or extreme under-control is associated with interpersonal problems. Findings have implications for identifying mechanisms of change for therapeutic approaches to emotion dysregulation and for understanding the over-controlled population, which has previously been overlooked.

When making decisions, individuals evaluate several possible outcomes of their choice; however, some display heightened reward sensitivity, despite the potential for future negative consequences, which can lead one to make risky choices. Rewards are processed in the mesolimbic dopamine reward system, and this system is in part modulated by genetic polymorphisms that are associated with dopamine transmission. The current study tested if genetic polymorphisms that are associated with enhanced dopamine neurotransmission will be more neurally reward sensitive, score higher on self-reported impulsivity, and make riskier choices. In a sample of 85 participants, five genetic polymorphisms were genotyped and used to create a genetic risk score that represented dopamine transmission efficiency. Two groups (high and low efficiency) were created via median split and then compared on neural reward sensitivity (assessed by event-related potentials, specifically, the medial-frontal negativity [MFN] and the error-related negativity), impulsivity (assessed via self-report), and risky choice (measured using the Balloon Analogue Risk Task and self-report measures). Results indicated that individuals with higher levels of dopamine displayed a less negative MFN and more drinking behaviors than those with lower levels of dopamine. These results suggest that individuals with higher levels of dopamine are less sensitive to punishments, which could lead them to make riskier choices.