Adolescents' risky decision-making activates neural networks related to social cognition and cognitive control processes

Neuroimaging studies of resting-state functional magnetic resonance imaging in eating disorders

Eating disorders (EDs), including anorexia nervosa (AN), bulimia nervosa (BN), binge-eating disorder (BED), and pica, are psychobehavioral conditions characterized by abnormal eating behaviors and an excessive preoccupation with weight and body shape. This review examines changes in brain regions and functional connectivity in ED patients over the past decade (2013-2023) using resting-state functional magnetic resonance imaging (rs-fMRI). Key findings highlight alterations in brain networks such as the default mode network (DMN), central executive network (CEN), and emotion regulation network (ERN). In individuals with AN, there is reduced functional connectivity in areas associated with facial information processing and social cognition, alongside increased connectivity in regions linked to sensory stimulation, aesthetic judgment, and social anxiety. Conversely, BED patients show diminished connectivity in the dorsal anterior cingulate cortex within the salience network and increased connectivity in the posterior cingulate cortex and medial prefrontal cortex within the DMN. These findings suggest that rs-fMRI could serve as a valuable biomarker for assessing brain function and predicting treatment outcomes in EDs, paving the way for personalized therapeutic strategies.

Preexposure to one social threat alters responses to another social threat: Behavioral and electrophysiological evidence

A recent Cyberball study has indicated that the experience of loss of control can affect how people process subsequent social exclusion. This "preexposure effect" supports the idea of a common cognitive system involved in the processing of different types of social threats. To test the validity of this assumption in the current study, we reversed the sequence of the preexposure setup. We measured the effects of social exclusion on the subsequent processing of loss of control utilizing event-related brain potentials (ERPs) and self-reports. In the control group (CG, n = 26), the transition to loss of control elicited significant increases in both the P3 amplitude and the self-reported negative mood. Replicating the results of the previous preexposure study, these effects were significantly reduced by the preexposure to an independent social threat (here: social exclusion). In contrast to previous findings, these effects were not modulated by the discontinuation (EG1disc, n = 25) or continuation (EG2cont, n = 24) of the preexposure threat. Given that the P3 effect is related to the violation of subjective expectations, these results support the notion that preexposure to a specific social threat has widespread effects on the individuals' expectancy of upcoming social participation and control.

Impaired social concept processing in persons with autistic-like traits

Situated models suggest that social concepts are grounded in interpersonal experience. However, few studies have tested this notion experimentally, and none has targeted individuals with reduced social interaction. Here, we assessed comprehension of text-level social and non-social concepts in persons with and without autistic-like traits. Participants read a social and a non-social text and answered questionnaires targeting social and non-social concepts, respectively. We compared behavioral outcomes, gauged their contribution to subject-level classification, and examined their association with validated measures of autism. Persons with autistic-like traits showed selective deficits in grasping text-level social concepts, even adjusting for intelligence, memory, and vocabulary. Also, social concept comprehension was the only variable that significantly classified between groups. Finally, social concept outcomes correlated negatively with measures of autism, including social interaction. Our results suggest that reduced interpersonal experience selectively compromises text-level social concept processing, offering empirical constraints for situated models of social semantics.

Social concepts and the cerebellum: behavioural and functional connectivity signatures in cerebellar ataxic patients

Neurocognitive research on social concepts underscores their reliance on fronto-temporo-limbic regions mediating broad socio-cognitive skills. Yet, the field has neglected another structure increasingly implicated in social cognition: the cerebellum. The present exploratory study examines this link combining a novel naturalistic text paradigm, a relevant atrophy model and functional magnetic resonance imaging. Fifteen cerebellar ataxia (CA) patients with focal cerebellar atrophy and 29 matched controls listened to a social text (highlighting interpersonal events) as well as a non-social text (focused on a single person's actions), and answered comprehension questionnaires. We compared behavioural outcomes between groups and examined their association with cerebellar connectivity. CA patients showed deficits in social text comprehension and normal scores in the non-social text. Also, social text outcomes in controls selectively correlated with connectivity between the cerebellum and key regions subserving multi-modal semantics and social cognition, including the superior and medial temporal gyri, the temporal pole and the insula. Conversely, brain-behaviour associations involving the cerebellum were abolished in the patients. Thus, cerebellar structures and connections seem involved in processing social concepts evoked by naturalistic discourse. Such findings invite new theoretical and translational developments integrating social neuroscience with embodied semantics. This article is part of the theme issue 'Concepts in interaction: social engagement and inner experiences'.

The neural correlates of mental fatigue and reward processing: A task-based fMRI study

Increasing time spent on the task (i.e., the time-on-task (ToT) effect) often results in mental fatigue. Typical effects of ToT are decreasing levels of task-related motivation and the deterioration of cognitive performance. However, a massive body of research indicates that the detrimental effects can be reversed by extrinsic motivators, for example, providing rewards to fatigued participants. Although several attempts have been made to identify brain areas involved in mental fatigue and related reward processing, the neural correlates are still less understood. In this study, we used the psychomotor vigilance task to induce mental fatigue and blood oxygen-level-dependent functional magnetic resonance imaging to investigate the neural correlates of the ToT effect and the reward effect (i.e., providing extra monetary reward after fatigue induction) in a healthy young sample. Our results were interpreted in a recently proposed neurocognitive framework. The activation of the right middle frontal gyrus, right insula and right anterior cingulate gyrus decreased as fatigue emerged and the cognitive performance dropped. However, after providing an extra reward, the cognitive performance, as well as activation of these areas, increased. Moreover, the activation levels of all of the mentioned areas were negatively associated with reaction times. Our results confirm that the middle frontal gyrus, insula and anterior cingulate cortex play crucial roles in cost-benefit evaluations, a potential background mechanism underlying fatigue, as suggested by the neurocognitive framework.

Body into Narrative: Behavioral and Neurophysiological Signatures of Action Text Processing After Ecological Motor Training

Embodied cognition research indicates that sensorimotor training can influence action concept processing. Yet, most studies employ isolated (pseudo)randomized stimuli and require repetitive single-effector responses, thus lacking ecological validity. Moreover, the neural signatures of these effects remain poorly understood. Here, we examined whether immersive bodily training can modulate behavioral and functional connectivity correlates of action-verb processing in naturalistic narratives. The study involved three phases. First, in the Pre-training phase, 32 healthy persons listened to an action text (rich in movement descriptions) and a non-action text (focused on its characters' perceptual and mental processes), completed comprehension questionnaires, and underwent resting-state electroencephalogram (EEG) recordings. Second, in the four-day Training phase, half the participants completed an exergaming intervention (eliciting full-body movements for 60 min a day) while the remaining half played static videogames (requiring no bodily engagement other than button presses). Finally, in the Post-training phase, all participants repeated the Pre-training protocol with different action and non-action texts and a new EEG session. We found that exergaming selectively reduced action-verb outcomes and fronto-posterior functional connectivity in the motor-sensitive ∼ 10-20 Hz range, both patterns being positively correlated. Conversely, static videogame playing yielded no specific effect on any linguistic category and did not modulate functional connectivity. Together, these findings suggest that action-verb processing and key neural correlates can be focally influenced by full-body motor training in a highly ecological setting. Our study illuminates the role of situated experience and sensorimotor circuits in action-concept processing, addressing calls for naturalistic insights on language embodiment.

Abnormal negative feedback processing in individuals with autistic traits in the Iowa gambling task: Evidence from behavior and event-related potentials

Value-based decision making plays an important role in social interaction. Previous studies have reported that individuals with autism spectrum disorder (ASD) exhibit deficits in terms of decision making. However, it is still unknown clearly whether individuals with high autistic traits within nonclinical populations employ abnormal neural substrates in value-based decision-making. To explore this issue, we investigated value-based decision making and its neural substrates in individuals with high and low autistic traits within a typically developing population who completed the revised Iowa gambling task (IGT) based on measurements of event-related potentials (ERPs). The IGT net scores were significantly lower in the group with high autistic traits than the group with low autistic traits in the fifth and sixth blocks. The ERP results showed that the feedback-related negativity (FRN) amplitude in individuals with high autistic traits allowed slight discrimination between positive and negative feedback in the low-risk option. The event-related spectral perturbations (ERSPs) and inter-trial coherence (ITC) of the theta-band frequency were also lower in the group with high autistic traits than the group with low autistic traits in the loss low-risk option. The results obtained in this study indicate that individuals with high autistic traits exhibit an unusual negative feedback process and relevant neural substrate. The FRN amplitude and theta-band oscillation may comprise a neural index of abnormal decision-making processes in individuals with high autistic traits. This study of a small sample may be considered an important step toward a more comprehensive understanding of the autism "spectrum" within a nonclinical population based on cognitive neuroscience.

Electrifying discourse: Anodal tDCS of the primary motor cortex selectively reduces action appraisal in naturalistic narratives

Non-invasive stimulation of the primary motor cortex (M1) modulates processing of decontextualized action words and sentences (i.e., verbal units denoting bodily motion). This suggests that language comprehension hinges on brain circuits mediating the bodily experiences evoked by verbal material. Yet, despite its relevance to constrain mechanistic language models, such a finding fails to reveal whether and how relevant circuits operate in the face of full-blown, everyday texts. Using a novel naturalistic discourse paradigm, we examined whether direct modulation of M1 excitability influences the grasping of narrated actions. Following random group assignment, participants received anodal transcranial direct current stimulation over the left M1, or sham stimulation of the same area, or anodal stimulation of the left ventrolateral prefrontal cortex. Immediately afterwards, they listened to action-laden and neutral stories and answered questions on information realized by verbs (denoting action and non-action processes) and circumstances (conveying locative or temporal details). Anodal stimulation of the left M1 selectively decreased outcomes on action-relative to non-action information -a pattern that discriminated between stimulated and sham participants with 74% accuracy. This result was particular to M1 and held irrespective of the subjects' working memory and vocabulary skills, further attesting to its specificity. Our findings suggest that offline modulation of motor-network excitability might lead to transient unavailability of putative resources needed to evoke actions in naturalistic texts, opening promising avenues for the language embodiment framework.

Money for me and money for friend: An ERP study of social reward processing in adolescents and adults

Peer relations during adolescence contribute significantly to the development of socio-cognitive skills and pro-sociality. The current study probed the characteristics of adolescent socio-cognitive processing through a card game where they earn money for self and friend. We investigated the choice preference and temporal dynamics of information processing by measuring ERP responses to wins or losses (valence) directed toward self and friend (recipient). Choice data showed that despite adults and adolescents earning equivalent amounts across recipients combined, adults won significantly more for self than a friend; no such difference was found in adolescents. The ERPs in response to choice outcomes showed that the valence information was processed earlier (at P2) in adults, while it was processed later (at P3) in adolescents. Furthermore, a strong effect of recipient was present in adults later in the time course (at P3), while such an effect was weak in adolescents; if any, adolescents showed sensitivity to recipient information earlier at P2. These ERP data suggest a relatively equal allocation of the P3-mediated attentional process to both self and friend's outcomes in adolescents, which parallels the choice behavior. Collectively our results characterize adolescent pro-sociality toward friends, reflecting the importance of peer relationship during this unique developmental period.

Incorporating the social context into neurocognitive models of adolescent decision-making: A neuroimaging meta-analysis

Neurobiological models of adolescent decision-making emphasize developmental changes in brain regions involved in affect (e.g., ventral striatum) and cognitive control (e.g., lateral prefrontal cortex). Although social context plays an important role in adolescent decision-making, current models do not discuss brain regions implicated in processing social information (e.g., dorsomedial prefrontal cortex). We conducted a coordinate-based meta-analysis using the Multilevel peak Kernel Density Analysis (MKDA) method to test the hypothesis that brain regions involved in affect, cognitive control, and social information processing support adolescent decision-making in social contexts (N = 21 functional neuroimaging studies; N = 1292 participants). Results indicated that dorsomedial prefrontal cortex, inferior frontal gyrus/insula and ventral striatum are consistently associated with adolescent decision-making in social contexts. Activity within these regions was modulated by the type of social context and social actors involved. Findings suggest including brain regions involved in social information processing into models of adolescent decision-making. We propose a 'constructionist' model, which describes psychological processes and corresponding neural networks related to affect, cognitive control, and social information processing.

Techniques of Neutralization: A Brain Network Perspective

Sykes and Matza introduced neutralization theory in 1957 to explain how juvenile delinquents retain a positive self-image when engaging in delinquent acts. Since then, aspects of neutralization theory have been incorporated into sociological and criminological theories to explain socially deviant behavior. Functional brain mapping research utilizing advanced magnetic resonance imaging techniques has identified complex, intrinsically organized, large-scale brain networks. Higher order operations commonly attributed to three brain networks (default mode network [DMN], central executive network [CEN], salience network [SN]) align closely with neutralization theory. This article briefly discusses brain networks in general and the DMN, CEN, and SN specifically. It also discusses how these networks are involved when engaging in the use of techniques of neutralization and offers implications for future research.

Adolescents, neurosciences et prise de décisions médicales : devrions-nous revoir certaines dispositions du Code civil du Québec?

Au Québec, le mineur de 14 ans et plus peut consentir seul aux soins médicaux requis par son état de santé, sauf exception. Or, les données provenant des neurosciences indiquent que : 1) l’acquisition de la « maturité cérébrale » est un processus continu, pouvant durer jusqu’à la mi-vingtaine, et que 2) certaines habiletés décisionnelles de l’adolescent, comme l’évaluation des risques et bénéfices à court et à long terme, seraient différentes de celles des adultes, surtout dans les situations émotivement chargées. Nous soumettons que, dans une perspective de protection de l’intérêt supérieur de l’enfant, la réalité neurophysiologique de l’adolescent devrait être prise en compte en contexte de soins de santé. Ainsi, nous questionnons le caractère adéquat de la présomption de capacité d’exercer un jugement de façon autonome dès l’âge de 14 ans et soulignons l’aspect paradoxal de la possibilité d’une intervention judiciaire en cas de refus de traitement. Nous questionnons également la pertinence de considérations d’âge dans le cadre de la relation entre le médecin et son patient, dès lors que la détermination de la capacité décisionnelle est une composante essentielle de l’obtention d’un consentement libre et éclairé. Enfin, nous questionnons l’exclusion des parents du processus décisionnel, à la fois en regard de leur responsabilité parentale et des bénéfices que peuvent représenter leurs conseils pour l’adolescent. Par conséquent, nous soumettons qu’une évaluation du bien-fondé de l’octroi d’un pouvoir décisionnel à l’adolescent de 14 ans et plus serait souhaitable et qu’un régime uniformisé tout au long de la minorité, avec de possibles exceptions, reflèterait mieux les connaissances scientifiques actuelles.

Neural Substrates of Counterfactual Emotions After Risky Decisions in Late Adolescents and Young Adults

Adolescents' neural substrates of emotional reactions to the consequences of risky decisions are poorly understood. In this functional magnetic resonance imaging study, 30 late adolescents and 30 young adults made risky and neutral decisions in social scenarios and received valenced outcomes. Negative outcomes in risky decisions eliciting regret, as compared with negative outcomes in neutral decisions eliciting disappointment, activated executive control (orbitofrontal cortex) and self-relevance regions (middle temporal gyrus [MTG], posterior cingulate cortex, and precuneus) for both age groups. Young adults showed more activation than adolescents in regret and disappointment as compared with relief and elation conditions in the avoidance (insula), action monitoring (inferior frontal gyrus, pre-SMA, and caudate), and social-cognition regions (superior temporal sulcus and MTG). These late socio-emotional developments may pave the way for more adaptive decision-making behavior in social contexts.

Altered Neural Activity during Irony Comprehension in Unaffected First-Degree Relatives of Schizophrenia Patients-An fMRI Study

Irony is a type of figurative language in which the literal meaning of the expression is the opposite of what the speaker intends to communicate. Even though schizophrenic patients are known as typically impaired in irony comprehension and in the underlying neural functions, to date no one has explored the neural correlates of figurative language comprehension in first-degree relatives of schizophrenic patients. In the present study, we examined the neural correlates of irony understanding in schizophrenic patients and in unaffected first-degree relatives of patients compared to healthy adults with functional MRI. Our aim was to investigate if possible alterations of the neural circuits supporting irony comprehension in first-degree relatives of patients with schizophrenia would fulfill the familiality criterion of an endophenotype. We examined 12 schizophrenic patients, 12 first-degree relatives of schizophrenia patients and 12 healthy controls with functional MRI while they were performing irony and control tasks. Different phases of irony processing were examined, such as context processing and ironic statement comprehension. Patients had significantly more difficulty understanding irony than controls or relatives. Patients also showed markedly different neural activation pattern compared to controls in both stages of irony processing. Although no significant differences were found in the performance of the irony tasks between the control group and the relative group, during the fMRI analysis, the relatives showed stronger brain activity in the left dorsolateral prefrontal cortex during the context processing phase of irony tasks than the control group. However, the controls demonstrated higher activations in the left dorsomedial prefrontal cortex and in the right inferior frontal gyrus during the ironic statement phase of the irony tasks than the relative group. Our results show that despite good task performance, first-degree relatives of schizophrenia patients had alterations in the neural circuits during irony processing. Thus, we suggest that neural alteration of irony comprehension could be a potential endophenotypic marker of schizophrenia.

Heightened activity in social reward networks is associated with adolescents' risky sexual behaviors

Adolescent sexual risk behavior can lead to serious health consequences, yet few investigations have addressed its neurodevelopmental mechanisms. Social neurocircuitry is postulated to underlie the development of risky sexual behavior, and response to social reward may be especially relevant. Typically developing adolescents (N=47; 18M, 29F; 16.3±1.4years; 42.5% sexual intercourse experience) completed a social reward fMRI task and reported their sexual risk behaviors (e.g., lifetime sexual partners) on the Youth Risk Behavior Survey (YRBS). Neural response and functional connectivity to social reward were compared for adolescents with higher- and lower-risk sexual behavior. Adolescents with higher-risk sexual behaviors demonstrated increased activation in the right precuneus and the right temporoparietal junction during receipt of social reward. Adolescents with higher-risk sexual behaviors also demonstrated greater functional connectivity between the precuneus and the temporoparietal junction bilaterally, dorsal medial prefrontal cortex, and left anterior insula/ventrolateral prefrontal cortex. The greater activation and functional connectivity in self-referential, social reward, and affective processing regions among higher sexual risk adolescents underscores the importance of social influence underlying sexual risk behaviors. Furthermore, results suggest an orientation towards and sensitivity to social rewards among youth engaging in higher-risk sexual behavior, perhaps as a consequence of or vulnerability to such behavior.

A neuroscience perspective on sexual risk behavior in adolescence and emerging adulthood

Late adolescence and emerging adulthood (specifically ages 15-24) represent a period of heightened sexual risk taking resulting in the greatest annual rates of sexually transmitted infections and unplanned pregnancies in the US population. Ongoing efforts to prevent such negative consequences are likely to benefit from a deepening of our understanding of biological mechanisms through which sexual risk taking emerges and biases decision making during this critical window. Here we present a neuroscience framework from which a mechanistic examination of sexual risk taking can be advanced. Specifically, we adapt the neurodevelopmental triadic model, which outlines how motivated behavior is governed by three systems: approach, avoidance, and regulation, to sexual decision making and subsequent risk behavior. We further propose a testable hypothesis of the triadic model, wherein relatively decreased threat-related amygdala reactivity and increased reward-related ventral striatum reactivity leads to sexual risk taking, which is particularly exaggerated during adolescence and young adulthood when there is an overexpression of dopaminergic neurons coupled with immature top-down prefrontal cortex regulation. We conclude by discussing how future research based on our adapted triadic model can inform ongoing efforts to improve intervention and prevention efforts.

Counterfactual Evaluation of Outcomes in Social Risk Decision-Making Situations: The Cognitive Developmental Paradox Revisited

We report a study that examined the existence of a cognitive developmental paradox in the counterfactual evaluation of decision-making outcomes. According to this paradox adolescents and young adults could be able to apply counterfactual reasoning and, yet, their counterfactual evaluation of outcomes could be biased in a salient socio-emotional context. To this aim, we analyzed the impact of health and social feedback on the counterfactual evaluation of outcomes in a laboratory decision-making task involving short narratives with the presence of peers. Forty risky (e.g., taking or refusing a drug), forty neutral decisions (e.g., eating a hamburger or a hotdog), and emotions felt following positive or negative outcomes were examined in 256 early, mid- and late adolescents, and young adults, evenly distributed. Results showed that emotional ratings to negative outcomes (regret and disappointment) but not to positive outcomes (relief and elation) were attenuated when feedback was provided. Evidence of development of cognitive decision-making capacities did also exist, as the capacity to perform faster emotional ratings and to differentially allocate more resources to the elaboration of emotional ratings when no feedback information was available increased with age. Overall, we interpret these findings as challenging the traditional cognitive developmental assumption that development necessarily proceeds from lesser to greater capacities, reflecting the impact of socio-emotional processes that could bias the counterfactual evaluation of social decision-making outcomes.

Searching for predictors of the risk decision-making process in social situations in the adolescence

This study examined how well self-reported sensation seeking, empathy and resistance to peer influence, and performance on the computer-based measure to evaluate risk-taking behavior (Balloon Analogue Risk Task, BART) predicted the risk decision-making process on the computer-based Social Context Decision Task (SCDT). Participants were 256 early, mid- and late adolescents and young adults, distributed by age and gender. Early adolescents scored lower on sensation seeking and empathy than late adolescents and young adults. Men scored higher on sensation seeking whereas women scored higher on empathy and resistance to peer influence. Regression models showed that riskiness on the BART was positively related to the percentage of risk elections and shorter decision times in the SCDT task, with the BART parameters accounting for variance in these measures beyond that accounted for by age, gender and Disinhibition. These results contributed to a more comprehensive multimethod assessment of the process of risk decision making in social situations.

Independent component analysis of functional networks for response inhibition: Inter-subject variation in stop signal reaction time

Cognitive control is a critical executive function. Many studies have combined general linear modeling and the stop signal task (SST) to delineate the component processes of cognitive control. For instance, by contrasting stop success (SS) and stop error (SE) trials in the SST, investigators examined regional responses to stop signal inhibition. In contrast to this parameterized approach, independent component analysis (ICA) elucidates brain networks subserving cognitive control. In our earlier work of 59 adults performing the SST during fMRI, we characterized six independent components (ICs). However, none of these ICs correlated with stop signal performance, raising questions about their behavioral validity. Here, in a larger sample (n = 100), we identified and explored 23 ICs for correlation with the stop signal reaction time (SSRT), a measure of the efficiency of response inhibition. At a corrected threshold (P < 0.0005), a paracentral lobule-midcingulate network and a left inferior parietal-supplementary motor-somatomotor network showed a positive correlation between SE beta weight and SSRT. In contrast, a midline cerebellum-thalamus-pallidum network showed a negative correlation between SE beta weight and SSRT. These findings suggest that motor preparation and execution prolongs the SSRT, likely via an interaction between the go and stop processes as suggested by the race model. Behaviorally, consistent with this hypothesis, the difference in G and SE reaction times is positively correlated with SSRT across subjects. These new results highlight the importance of cognitive motor regions in response inhibition and support the utility of ICA in uncovering functional networks for cognitive control in the SST.

Influence of dorsolateral prefrontal cortex and ventral striatum on risk avoidance in addiction: a mediation analysis

BACKGROUND

Alterations in frontal and striatal function are hypothesized to underlie risky decision making in drug users, but how these regions interact to affect behavior is incompletely understood. We used mediation analysis to investigate how prefrontal cortex and ventral striatum together influence risk avoidance in abstinent drug users.

METHOD

Thirty-seven abstinent substance-dependent individuals (SDI) and 43 controls underwent fMRI while performing a decision-making task involving risk and reward. Analyses of a priori regions-of-interest tested whether activity in dorsolateral prefrontal cortex (DLPFC) and ventral striatum (VST) explained group differences in risk avoidance. Whole-brain analysis was conducted to identify brain regions influencing the negative VST-risk avoidance relationship.

RESULTS

Right DLPFC (RDLPFC) positively mediated the group-risk avoidance relationship (p < 0.05); RDLPFC activity was higher in SDI and predicted higher risk avoidance across groups, controlling for SDI vs.

CONTROLS

Conversely, VST activity negatively influenced risk avoidance (p < 0.05); it was higher in SDI, and predicted lower risk avoidance. Whole-brain analysis revealed that, across group, RDLPFC and left temporal-parietal junction positively (p ≤ 0.001) while right thalamus and left middle frontal gyrus negatively (p < 0.005) mediated the VST activity-risk avoidance relationship.

CONCLUSION

RDLPFC activity mediated less risky decision making while VST mediated more risky decision making across drug users and controls. These results suggest a dual pathway underlying decision making, which, if imbalanced, may adversely influence choices involving risk. Modeling contributions of multiple brain systems to behavior through mediation analysis could lead to a better understanding of mechanisms of behavior and suggest neuromodulatory treatments for addiction.

Increased brain activity to unpleasant stimuli in individuals with the 7R allele of the DRD4 gene

The aim of the study was to examine functional brain activity in response to unpleasant images in individuals with the 7-repeat (7R) allele compared to individuals with the 4-repeat (4R) allele of the dopamine receptor D4 (DRD4) gene (VNTR in exon 3). Based on the response ready hypothesis, individuals with the DRD4-4R/7R genotype were expected to show greater functional brain activity in response to unpleasant compared to neutral stimuli in specific regions of the frontal, temporal, parietal and limbic lobes, which form the networks involved in attentional, emotional, and preparatory responses. Functional Magnetic Resonance Imaging activity was studied in 26 young adults (13 with the DRD4-4R/7R genotype and 13 with the DRD4-4R/4R genotype). Participants were asked to look at and subjectively rate unpleasant and neutral images. Results showed increased brain activity in response to unpleasant images compared to neutral images in the right temporal lobe in participants with the DRD4-4R/7R genotype versus participants with the DRD4-4R/4R genotype. The increase in right temporal lobe activity in individuals with DRD4-4R/7R suggests greater involvement in processing negative emotional stimuli. Intriguingly, no differences were found between the two genotypes in the subjective ratings of the images. The findings corroborate the response ready hypothesis, which suggests that individuals with the 7R allele are more responsive to negative emotional stimuli compared to individuals with the 4R allele of the DRD4 gene.

Theory of Mind in Bipolar Disorder, with Comparison to the Impairments Observed in Schizophrenia

Our ability to make sense of information on the potential intentions and dispositions of others is of paramount importance for understanding their communicative intent, and for judging what an appropriate reaction might be. Thus, anything that impinges on this ability has the potential to cause significant social impairment, and compromise an individual's level of functioning. Both bipolar disorder and schizophrenia are known to feature theory of mind impairment. We conducted a theoretical review to determine the extent and types of theory of mind impairment in bipolar disorder, and evaluate their relationship to medication and symptoms. We also considered possible mediatory mechanisms, and set out to discover what else could be learnt about the impairment in bipolar disorder by comparison to the profile of impairment in schizophrenia. The literature established that in bipolar disorder (i) some form of theory of mind impairment has been observed in all mood states, including euthymia, (ii) the form of theory of mind assessed and task used to make the assessment influence the impairment observed, and (iii) there might be some relationship to cognitive impairment, although a relationship to standard clinical variables was harder to establish. What also became clear in the literature on bipolar disorder itself was the possible relationship of theory of mind impairment to history of psychotic symptoms. Direct comparative studies, including patients with schizophrenia, were thus examined, and provided several important directions for future research on the bases of impairment in bipolar disorder. Particularly prominent was the issue of whether theory of mind impairment could be considered a candidate endophenotype for the psychoses, although current evidence suggests that this may be premature. The differences in impairment across schizophrenia and bipolar disorder may, however, have genuine differential effects on social functioning and the likely success of remediation.

A Two-Hit Model of Autism: Adolescence as the Second Hit

Adolescence brings dramatic changes in behavior and neural organization. Unfortunately, for some 30% of individuals with autism, there is marked decline in adaptive functioning during adolescence. We propose a two-hit model of autism. First, early perturbations in neural development function as a "first hit" that sets up a neural system that is "built to fail" in the face of a second hit. Second, the confluence of pubertal hormones, neural reorganization, and increasing social demands during adolescence provides the "second hit" that interferes with the ability to transition into adult social roles and levels of adaptive functioning. In support of this model, we review evidence about adolescent-specific neural and behavioral development in autism. We conclude with predictions and recommendations for empirical investigation about several domains in which developmental trajectories for individuals with autism may be uniquely deterred in adolescence.