Decision making and social neurocognition during adolescence

Adolescents show a tendency to engage in risky activities, such as dangerous driving and unsafe sex. This has led to the suggestion that adolescents are poor decision-makers, and are risk-seeking in general. The first two chapters of this thesis describe studies investigating adolescent decision-making using probabilistic decision-making tasks. In Chapter 2, the tendency to seek risk, and the ability to integrate probability and reward information to make an optimal decision, is investigated in child, adolescent and adult participants. The emotional response to outcomes was also investigated. In Chapter 3, a computational approach is adopted to investigate the role of positive and negative performance feedback (wins and losses) in a probabilistic decision-making task in adolescents and in adults. The role of social-emotional factors in decision-making was also investigated. Adolescence is characterised by social and emotional development, as well as development in the functional brain correlates of social-emotional processing. Therefore, Chapters 4 to 6 focus on adolescent social-emotional processing using behavioural and functional neuroimaging methods. In Chapter 4, results are presented from a study of self-reported social and basic emotions across adolescence, where social emotions (e.g. embarrassment) are defined as emotions that require an awareness of others’ mental states (e.g. emotions, opinions, desires). In Chapter 5, the neural correlates of social and basic emotion processing are investigated in adolescents and in adults, using functional magnetic resonance imaging (fMRI). Finally, in Chapter 6, these fMRI data are reanalysed using a technique known as psycho-physiological interaction (PPI) analysis, to look at age-associated changes in effective connectivity. Results are discussed in the context of social cognition and neuroanatomical development

The Developmental Mismatch in Structural Brain Maturation during Adolescence

Regions of the human brain develop at different rates across the first two decades of life, with some maturing before others. It has been hypothesized that a mismatch in the timing of maturation between subcortical regions (involved in affect and reward processing) and prefrontal regions (involved in cognitive control) underlies the increase in risk-taking and sensation-seeking behaviors observed during adolescence. Most support for this 'dual systems' hypothesis relies on cross-sectional data, and it is not known whether this pattern is present at an individual level. The current study utilizes longitudinal structural magnetic resonance imaging (MRI) data to describe the developmental trajectories of regions associated with risk-taking and sensation-seeking behaviors, namely, the amygdala, nucleus accumbens (NAcc) and prefrontal cortex (PFC). Structural trajectories of gray matter volumes were analyzed using FreeSurfer in 33 participants aged 7-30 years, each of whom had at least three high-quality MRI scans spanning three developmental periods: late childhood, adolescence and early adulthood (total 152 scans). The majority of individuals in our sample showed relatively earlier maturation in the amygdala and/or NAcc compared to the PFC, providing evidence for a mismatch in the timing of structural maturation between these structures. We then related individual developmental trajectories to retrospectively assessed self-reported risk-taking and sensation-seeking behaviors during adolescence in a subsample of 24 participants. Analysis of this smaller sample failed to find a relationship between the presence of a mismatch in brain maturation and risk-taking and sensation-seeking behaviors during adolescence. Taken together, it appears that the developmental mismatch in structural brain maturation is present in neurotypically developing individuals. This pattern of development did not directly relate to self-reported behaviors at an individual level in our sample, highlighting the need for prospective studies combining anatomical and behavioral measures. © 2014 S. Karger AG, Basel

Interactions Between the Basolateral Amygdala and Ventral Striatum During Probabilistic Learning in Children and Associations with Individual Differences in Free Cortisol

Stress can drastically alter the behavioural and functional correlates of feedback learning; however, the functional correlates of these effects are poorly understood, particularly in children. In the present study, typically developing children between the ages of 9- and 11-years-old completed a probabilistic learning task with both appetitive and aversive outcomes in a magnetic resonance imaging scanner. Anticipatory stress to the experimental environment was measured via salivary cortisol at baseline and prior to completion of the task. Although baseline and pre-MRI cortisol values were not reliably different at the group level, subsequent analyses revealed that the basolateral amygdala was less responsive to positive feedback in children with higher pre-MRI cortisol levels. Furthermore, individual differences in feedback-related basolateral amygdala activity were positively associated with differences in striatal activity. Thus, the basolateral amygdala may be particularly sensitive to individual differences in active cortisol levels, and may also modulate striatal feedback sensitivity

What does the amygdala contribute to social cognition?

The amygdala has received intense recent attention from neuroscientists investigating its function at the molecular, cellular, systems, cognitive, and clinical level. It clearly contributes to processing emotionally and socially relevant information, yet a unifying description and computational account have been lacking. The difficulty of tying together the various studies stems in part from the sheer diversity of approaches and species studied, in part from the amygdala's inherent heterogeneity in terms of its component nuclei, and in part because different investigators have simply been interested in different topics. Yet, a synthesis now seems close at hand in combining new results from social neuroscience with data from neuroeconomics and reward learning. The amygdala processes a psychological stimulus dimension related to saliency or relevance; mechanisms have been identified to link it to processing unpredictability; and insights from reward learning have situated it within a network of structures that include the prefrontal cortex and the ventral striatum in processing the current value of stimuli. These aspects help to clarify the amygdala's contributions to recognizing emotion from faces, to social behavior toward conspecifics, and to reward learning and instrumental behavior

Incentive Processing and Inhibitory Control in Adolescents and Young Adults

Adolescents are known to demonstrate normative increases in risk-taking behaviors. Understanding the interaction between incentive (reward, punishment) processing and basic cognitive control abilities, both of which are still maturing into adolescence, may provide insight on the basic mechanisms contributing to this complex behavioral phenomenon. In this dissertation, we present a compilation of papers aimed at characterizing the influence of potential reward gain or loss on response inhibition performance and supporting brain circuitry in adolescents and adults. In study 1, we use fast, event-related functional magnetic resonance imaging (fMRI) to examine the neural circuitry supporting perfomance on an antisaccade task with reward or neutral contingencies added to each trial. Results indicate that components of the adolescent reward system exhibit an initially sluggish, then eventually overactive response to rewards, as well as limited recruitment in regions supporting the executive assessment of rewards. In study 2, the effects of different magnitudes of potential gains and losses on antisaccade task performance were examined. Results indicate that higher compared to lower magnitude reward contingencies differentially affect adolescent, but not adult, response suppression abilities. Furthemore, both age groups performed consistently well (low error rates) on punishment trials. In study 3, adolescents and adults underwent fast, event-related fMRI as they performed a rewarded antisaccade task with fixed-magnitude reward and punishment stimuli, previously determined to result in equivalent levels of behavioral performance across the age groups (study 2). Additionally, auditory, performance-based feedback was provided on each trial. fMRI results indicate that during detection of reward cues, adolescents do not show the same early recruitment of oculomotor control regions evident in adults. Furthermore, adolescents demonstrated temporally extended responses in several brain regions (e.g., orbitofrontal cortex, supplementary eye field) during the preparatory period of potential punishment trials, reflecting possible immaturities in mechanisms underlying potential loss or 'risk' anticipation. Finally, adults demonstrated enhanced activity in the ventral striatum and cortical eye fields during the response/feedback epoch, suggesting more mature consummatory processing. Collectively, the results of these studies demonstrate protracted development of higher-order executive aspects of reward processing and its interaction with response inhibition abilites into adolescence

A 4-Year Longitudinal Neuroimaging Study of Cognitive Control Using Latent Growth Modeling: Developmental Changes and Brain-Behavior Associations

Despite theoretical models suggesting developmental changes in neural substrates of cognitive control in adolescence, empirical research has rarely examined intraindividual changes in cognitive control-related brain activation using multi-wave multivariate longitudinal data. We used longitudinal repeated measures of brain activation and behavioral performance during the multi-source interference task (MSIT) from 167 adolescents (53% male) who were assessed annually over four years from ages 13 to 17 years. We applied latent growth modeling to delineate the pattern of brain activation changes over time and to examine longitudinal associations between brain activation and behavioral performance. We identified brain regions that showed differential change patterns: (1) the fronto-parietal regions that involved bilateral insula, bilateral middle frontal gyrus, left pre-supplementary motor area, left inferior parietal lobule, and right precuneus; and (2) the rostral anterior cingulate cortex (rACC) region. Longitudinal confirmatory factor analyses of the fronto-parietal regions revealed strong measurement invariance across time implying that multivariate functional magnetic resonance imaging data during cognitive control can be measured reliably over time. Latent basis growth models indicated that fronto-parietal activation decreased over time, whereas rACC activation increased over time. In addition, behavioral performance data, age-related improvement was indicated by a decreasing trajectory of intraindividual variability in response time across four years. Testing longitudinal brain-behavior associations using multivariate growth models revealed that better behavioral cognitive control was associated with lower fronto-parietal activation, but the change in behavioral performance was not related to the change in brain activation. The current findings suggest that reduced effects of cognitive interference indicated by fronto-parietal recruitment may be a marker of a maturing brain that underlies better cognitive control performance during adolescence

The cognitive neuroscience of visual working memory

Visual working memory allows us to temporarily maintain and manipulate visual information in order to solve a task. The study of the brain mechanisms underlying this function began more than half a century ago, with Scoville and Milner’s (1957) seminal discoveries with amnesic patients. This timely collection of papers brings together diverse perspectives on the cognitive neuroscience of visual working memory from multiple fields that have traditionally been fairly disjointed: human neuroimaging, electrophysiological, behavioural and animal lesion studies, investigating both the developing and the adult brain