Viewing the personality traits through a cerebellar lens. A focus on the constructs of novelty seeking, harm avoidance, and alexithymia

The variance in the range of personality trait expression appears to be linked to structural variance in specific brain regions. In evidencing associations between personality factors and neurobiological measures, it seems evident that the cerebellum has not been up to now thought as having a key role in personality. This paper will review the most recent structural and functional neuroimaging literature that engages the cerebellum in personality traits, as novelty seeking and harm avoidance, and it will discuss the findings in the context of contemporary theories of affective and cognitive cerebellar function. By using region of interest (ROI)- and voxel-based approaches, we recently evidenced that the cerebellar volumes correlate positively with novelty seeking scores and negatively with harm avoidance scores. Subjects who search for new situations as a novelty seeker does (and a harm avoiding does not do) show a different engagement of their cerebellar circuitries in order to rapidly adapt to changing environments. The emerging model of cerebellar functionality may explain how the cerebellar abilities in planning, controlling, and putting into action the behavior are associated to normal or abnormal personality constructs. In this framework, it is worth reporting that increased cerebellar volumes are even associated with high scores in alexithymia, construct of personality characterized by impairment in cognitive, emotional, and affective processing. On such a basis, it seems necessary to go over the traditional cortico-centric view of personality constructs and to address the function of the cerebellar system in sustaining aspects of motivational network that characterizes the different temperamental trait

Assessment of sensation seeking personality type using behavioral and functional neuroimaging measures

2020 Fall.Includes bibliographical references.Sensation seeking personality type, in which an individual has the propensity to engage in risky behaviors while searching for an optimal level of stimulation, is associated with a variety of negative health outcomes, such as higher rates of substance misuse, gambling, and self-harm. It is important to develop methods to identify those at higher risk of engaging in such health risk behaviors. Historically, sensation seeking has been primarily measured using self-report surveys. Providing additional measures of sensation seeking, such as through behavioral assessment or biomarkers, would aid our measurement of the sensation seeking personality type. The present work sought to create a new behavioral measure of sensation seeking personality type, the Sensation Seeking Dot Probe Task (SSDP), that measures an individual's attentional bias towards sensation seeking imagery. Further, the SSDP task was combined with functional Near Infrared Spectroscopy, which utilizes the spectral differences of hemoglobin in the brain to measure neural activity, to identify neural correlates of attention to sensation seeking imagery and relate them to the Sensation Seeking Personality Type scale. I hypothesized that the SSDP would be as effective in identifying sensation seeking as the self-report scale, and that attention to sensation seeking images would correlate with changes in neural activity in the prefrontal cortex and orbitofrontal cortex (regions associated with executive control and decision making) that would be greater in high sensation seeking individuals. While the SSDP did not find significant differences in accuracy or reaction time, the typical measures used in attentional bias dot-probe tasks, there was a significant difference in selection of sensation seeking imagery when paired with neutral control imagery. There were also significantly different changes in activity during sensation seeking congruent tasks in areas of the lateral prefrontal cortex for high sensation seeking individuals. These results suggest functional and behavioral differences measurable in high sensation seekers, and future tasks can use these findings to lead to a greater understanding of the personality type

Conflict between Threat Sensitivity and Sensation Seeking in the Adolescent Brain : Role of the Hippocampus, and Neurobehavioural Plasticity Induced by Pleasurable Early Enriched Experience

Adolescence is characterized both by the exacerbation of the experience of anxiety, fear or threat, on one hand, and by increased reward seeking (reward sensitivity) and risk taking on the other hand. The rise of these apparently opposite processes, i.e., threat-related anxiety and reward-related sensation seeking, seems to stem from a relatively decreased top-down inhibition of amygdala and striatal circuits by regulatory systems (e.g., prefrontal cortex, hippocampus) that mature later. The present commentary article aims to discuss recent related literature and focusses on two main issues: (i) the septo-hippocampal system (in particular the ventral hippocampus) might be a crucial region for the regulation of approach-avoidance conflict and also for the selection of the most appropriate responses during adolescence, and (ii) developmental studies involving early-life pleasurable-enriched experience (as opposed to early-life adversity) might be a useful study paradigm in order to decipher whether neuroplasticity induced by such experiences (for example, in the hippocampus and associated circuitry) may lead to better top-down inhibition and more "balanced" adolescent responses to environmental demands

DEVELOPMENTAL AND INDIVIDUAL DIFFERENCES IN REWARD PROCESSING ACROSS CHILDHOOD AND ADOLESCENCE

Adolescence is a developmental period characterized by maturation across multiple domains. This maturation is not without difficulties, however, as adolescents also display increased negative mood, conflict with parents, and risk-taking behaviors. Increased risk-taking is thought to be the byproduct of changes in reward circuits in the brain, and while a solid foundation of research has provided evidence for changes in reward processing during adolescence compared to adulthood, little is known about the changes that occur from childhood into adolescence. The current study addresses this gap in the literature with an investigation of changes in behavioral performance on a reward-processing task using a cross-sectional sample of children and adolescents. Three primary findings emerged from this study. First, adolescents displayed faster reaction times than 8-year-olds. Second, subjects responded faster and more accurately on trials with greater potential rewards. Finally, individual differences were related to reward sensitivity, reaction times, and response accuracies

Judgment and decision making in adolescence

In this article, we review the most important findings to have emerged during the past 10 years in the study of judgment and decision making (JDM) in adolescence and look ahead to possible new directions in this burgeoning area of research. Three inter-related shifts in research emphasis are of particular importance and serve to organize this review. First, research grounded in normative models of JDM has moved beyond the study of age differences in risk perception and toward a dynamic account of the factors predicting adolescent decisions. Second, the field has seen widespread adoption of dual-process models of cognitive development that describe 2 relatively independent modes of information processing, typically contrasting an analytic (cold) system with an experiential (hot) one. Finally, there has been an increase in attention to the social, emotional, and self-regulatory factors that influence JDM. This shift in focus reflects the growing influence of findings from developmental neuroscience, which describe a pattern of structural and functional maturation that may set the stage for a heightened propensity to make risky decisions in adolescence

Social risk in adolescence

Adolescence, defined as 10-24 years, is a time of heightened sensitivity to the negative effects of social rejection. Avoiding social risks – decisions or actions that could lead to social rejection - may therefore be important for adolescents, for whom social status and acceptance predicts future mental and physical health. In this thesis, I describe a series of studies that investigated the relationship between social risk and adolescence. In my first study, I developed a novel self-report measure of concern for health and social risk behaviours. I assessed age-related differences in concern for health and social risk between adolescence and adulthood, and whether these were related to rejection sensitivity and depressive symptomatology. In my second study, I explored the degree to which adolescents’ engagement in health risks and illegal behaviours was related to whether or not they perceived these behaviours to increase their likability. I also investigated how this relationship is impacted by adolescents’ experience of victimisation. In my third study, I used network analysis to explore the link between sexual minority status, depression, interpersonal relationships and health risk behaviours in a large cohort study of adolescents. In my fourth study, I designed an experiment to measure the extent to which adolescents versus adults show a preference for social versus non-social stimuli within an academic diligence task. I discuss how my findings suggest adolescence to be a period of heightened sensitivity to social risk, and how this impacts decisions to engage in risk taking behaviour. I consider how my findings relate to legal and policy issues around the minimum age of criminal responsibility, joint enterprise convictions and the use of peer-led approaches for behaviour change

Age and Impulsive Behavior in Drug Addiction: A Review of Past Research and Future

Impulsive behavior is implicated in the initiation, maintenance, and relapse of drug-seeking behaviors involved in drug addiction. Research shows that changes in impulsive behavior across the lifespan contribute to drug use and addiction. The goal of this review is to examine existing research on the relationship between impulsive behavior and drug use across the lifespan and to recommend directions for future research. Three domains of impulsive behavior are explored in this review: impulsive behavior-related personality traits, delay discounting, and prepotent response inhibition. First, we present previous research on these three domains of impulsive behavior and drug use across developmental stages. Then, we discuss how changes in impulsive behavior across the lifespan are implicated in the progression of drug use and addiction. Finally, we discuss the relatively limited attention given to middle-to-older adults in the current literature, consider the validity of the measures used to assess impulsive behavior in middle-to-older adulthood, and suggest recommendations for future research

Beyond Stereotypes of Adolescent Risk Taking: Placing the Adolescent Brain in Developmental Context

Recent neuroscience models of adolescent brain development attribute the morbidity and mortality of this period to structural and functional imbalances between more fully developed limbic regions that subserve reward and emotion as opposed to those that enable cognitive control. We challenge this interpretation of adolescent development by distinguishing risk-taking that peaks during adolescence (sensation seeking and impulsive action) from risk taking that declines monotonically from childhood to adulthood (impulsive choice and other decisions under known risk). Sensation seeking is primarily motivated by exploration of the environment under ambiguous risk contexts, while impulsive action, which is likely to be maladaptive, is more characteristic of a subset of youth with weak control over limbic motivation. Risk taking that declines monotonically from childhood to adulthood occurs primarily under conditions of known risks and reflects increases in executive function as well as aversion to risk based on increases in gist-based reasoning. We propose an alternative Lifespan Wisdom Model that highlights the importance of experience gained through exploration during adolescence. We propose, therefore, that brain models that recognize the adaptive roles that cognition and experience play during adolescence provide a more complete and helpful picture of this period of development