The development of the ventral prefrontal cortex and social flexibility

A conserved pattern of differential expansion of cortical areas in simian primates

The layout of areas in the cerebral cortex of different primates is quite similar, despite significant variations in brain size. However, it is clear that larger brains are not simply scaled up versions of smaller brains: some regions of the cortex are disproportionately large in larger species. It is currently debated whether these expanded areas arise through natural selection pressures for increased cognitive capacity or as a result of the application of a common developmental sequence on different scales. Here, we used computational methods to map and quantify the expansion of the cortex in simian primates of different sizes to investigate whether there is any common pattern of cortical expansion. Surface models of the marmoset, capuchin, and macaque monkey cortex were registered using the software package CARET and the spherical landmark vector difference algorithm. The registration was constrained by the location of identified homologous cortical areas. When comparing marmosets with both capuchins and macaques, we found a high degree of expansion in the temporal parietal junction, the ventrolateral prefrontal cortex, and the dorsal anterior cingulate cortex, all of which are high-level association areas typically involved in complex cognitive and behavioral functions. These expanded maps correlated well with previously published macaque to human registrations, suggesting that there is a general pattern of primate cortical scaling.

The brain on stress: vulnerability and plasticity of the prefrontal cortex over the life course

The prefrontal cortex (PFC) is involved in working memory and self-regulatory and goal-directed behaviors and displays remarkable structural and functional plasticity over the life course. Neural circuitry, molecular profiles, and neurochemistry can be changed by experiences, which influence behavior as well as neuroendocrine and autonomic function. Such effects have a particular impact during infancy and in adolescence. Behavioral stress affects both the structure and function of PFC, though such effects are not necessarily permanent, as young animals show remarkable neuronal resilience if the stress is discontinued. During aging, neurons within the PFC become less resilient to stress. There are also sex differences in the PFC response to stressors. While such stress and sex hormone-related alterations occur in regions mediating the highest levels of cognitive function and self-regulatory control, the fact that they are not necessarily permanent has implications for future behavior-based therapies that harness neural plasticity for recovery.

Neuroimaging studies of pediatric social anxiety: paradigms, pitfalls and a new direction for investigating the neural mechanisms

Social Anxiety Disorder (SAD) is a common and debilitating condition that typically manifests in adolescence. Here we describe cognitive factors engaged by brain-imaging tasks, which model the peer-based social interactions that evoke symptoms of SAD. We then present preliminary results from the Virtual School paradigm, a novel peer-based social interaction task. This paradigm is designed to investigate the neural mechanisms mediating individual differences in social response flexibility and in participants' responses to uncertainty in social contexts. We discuss the utility of this new paradigm for research on brain function and developmental psychopathology.

Working memory deficits in high-functioning adolescents with autism spectrum disorders: neuropsychological and neuroimaging correlates

Working memory is a temporary storage system under attentional control. It is believed to play a central role in online processing of complex cognitive information and may also play a role in social cognition and interpersonal interactions. Adolescents with a disorder on the autism spectrum display problems in precisely these domains. Social impairments, communication difficulties, and repetitive interests and activities are core domains of autism spectrum disorders (ASD), and executive function problems are often seen throughout the spectrum. As the main cognitive theories of ASD, including the theory of mind deficit hypotheses, weak central coherence account, and the executive dysfunction theory, still fail to explain the broad spectrum of symptoms, a new perspective on the etiology of ASD is needed. Deficits in working memory are central to many theories of psychopathology, and are generally linked to frontal-lobe dysfunction. This article will review neuropsychological and (functional) brain imaging studies on working memory in adolescents with ASD. Although still disputed, it is concluded that within the working memory system specific problems of spatial working memory are often seen in adolescents with ASD. These problems increase when information is more complex and greater demands on working memory are made. Neuroimaging studies indicate a more global working memory processing or connectivity deficiency, rather than a focused deficit in the prefrontal cortex. More research is needed to relate these working memory difficulties and neuroimaging results in ASD to the behavioral difficulties as seen in individuals with a disorder on the autism spectrum.

Steroid hormone signaling is involved in the age-dependent behavioral response to sex pheromone in the adult male moth Agrotis ipsilon

In most animals, including insects, male reproduction depends on the detection and processing of female-produced sex pheromones. In the male moth, Agrotis ipsilon, both behavioral response and neuronal sensitivity in the primary olfactory center, the antennal lobe (AL), to female sex pheromone are age- and hormone-dependent. In many animal species, steroids are known to act at the brain level to modulate the responsiveness to sexually relevant chemical cues. We aimed to address the hypothesis that the steroidal system and in particular 20-hydroxyecdysone (20E), the main insect steroid hormone, might also be involved in this olfactory plasticity. Therefore, we first cloned the nuclear ecdysteroid receptor EcR (AipsEcR) and its partner Ultraspiracle (AipsUSP) of A. ipsilon, the expression of which increased concomitantly with age in ALs. Injection of 20E into young sexually immature males led to an increase in both responsiveness to sex pheromone and amount of AipsEcR and AipsUSP in their ALs. Conversely, the behavioral response decreased in older, sexually mature males after injection of cucurbitacin B (CurB), an antagonist of the 20E/EcR/USP complex. Also, the amount of AipsEcR and AipsUSP significantly declined after treatment with CurB. These results suggest that 20E is involved in the expression of sexual behavior via the EcR/USP signaling pathway, probably acting on central pheromone processing in A. ipsilon.

Getting serious with retinopathy: approaching an integrated hypothesis for central serous chorioretinopathy

Development of the prefrontal cortex is believed to play an important role in the maturation of higher cognitive functions such as decision making, cognition and control of part of the neural element of the stress response. The prefrontal cortex undergoes considerable maturation during childhood, including a reduction of synaptic and neural density, a growth of dendrites, and an increase in white matter volume, thereby forming distributed neural networks appropriate for complex cognitive processing, but maturation is not complete until approximately 25 years of age. Serotonin and its receptors (HTRs) play critical roles in brain development and in the regulation of cognition, mood, and anxiety. HTRs are highly expressed in the human prefrontal cortex and exert control over prefrontal excitability. Studies of post-mortem prefrontal brain tissue found distinct developmental patterns of expression of these receptors occurring in early postnatal development and also into adulthood. The general pattern of improved cognitive control and emotion regulation with maturation of the prefrontal cortex, suggests a linear increase in development from childhood to adulthood. Animal studies have shown that dopamine is crucial for communication between the accumbens, amygdala, and prefrontal cortex. Dopamine projections to the prefrontal cortex continue to develop into early adulthood. Central Serous Chorioretinopathy (CSC) is an eye disease affecting people of working age, commonly resulting in repeated unpredictable visually disabling serous retinal detachments and occasionally leading to irreversible reduction in central vision. The disease has been closely linked to the stress response. Despite a concerted effort to understand aetiopathogenesis, disease mechanisms are still largely unclear. This paper, supported by evidence in the literature, proposes a systemic approach to CSC and explains how interactions of the eye with the cerebral cortex could lead to disease. We propose that the lack of development of the neural element of the stress response and in particular the prefrontal cortex is the reason for the absence of CSC in childhood and adolescence. Additionally, we attempt to explain why excess stress hormones do not always result in CSC and why acute attacks occur only once in over half of cases. Finally, we summarise the implications that an integrated systemic hypothesis has for future CSC research and the requirement of a holistic management practice for the identification and treatment of patients with CSC.

Special issue on the teenage brain: Sensitivity to social evaluation

Relative to childhood, peer relationships take on a heightened importance during adolescence. Might adolescents be highly attuned to information that concerns when and how they are being evaluated, and what their peers think of them? This review evaluates how continuing brain development - which influences brain function - partially explains or reflects adolescents' attunement to social evaluation. Though preliminary, evidence is mounting to suggest that while processing information relevant to social evaluation and the internal states of other people, adolescents respond with greater emotional intensity and corresponding nonlinear recruitment of socioaffective brain circuitry. This review highlights research findings that relate trajectories of brain development and social behavior, and discusses promising avenues of future research that will inform how brain development might lead adolescents sensitized to social evaluation.

Understanding adolescence as a period of social-affective engagement and goal flexibility

Research has demonstrated that extensive structural and functional brain development continues throughout adolescence. A popular notion emerging from this work states that a relative immaturity in frontal cortical neural systems could explain adolescents' high rates of risk-taking, substance use and other dangerous behaviours. However, developmental neuroimaging studies do not support a simple model of frontal cortical immaturity. Rather, growing evidence points to the importance of changes in social and affective processing, which begin around the onset of puberty, as crucial to understanding these adolescent vulnerabilities. These changes in social-affective processing also may confer some adaptive advantages, such as greater flexibility in adjusting one's intrinsic motivations and goal priorities amidst changing social contexts in adolescence.

Socio-cultural effects on children's initiation of joint attention

Exchanging gazes with a social partner in response to an event in the environment is considered an effective means to direct attention, share affective experiences, and highlight a target in the environment. This behavior appears during infancy and plays an important role in children's learning and in shaping their socio-emotional development. It has been suggested that cultural values of the community affect socio-emotional development through attentional dynamics of social reference (Rogoff et al., 1993). Maturational processes of brain-circuits have been found to mediate socio-cultural learning and the behavioral manifestation of cultural norms starting at preschool age (Nelson and Guyer, 2011). The aim of the current study was to investigate the relations between cultural ecology levels and children's joint attention (JA). Initiation of JA bids was studied empirically as a function of the level of social load of the target toy (3 levels), the community level of adherence to traditional values (3 levels), parental education (2 levels), and gender. Sixty-two kindergarten aged children were enrolled in a structured toy-exploration task, during which they were presented with toys of various social loads, with social agents (i.e., mother and experimenter) present nearby, and non-social distracters presented intermittently. Measurements included the child's number of JA bids and the extent of positive affect. Analysis of variance indicated that the child's initiation of JA toward the social partner was affected by all levels of cultural ecology (i.e., toy's social load, adherence to tradition values, parental education, gender), thus supporting the study's hypotheses. The effects were such that overall, children, particularly girls' JA initiation was augmented in social toys and moderated by the socio-cultural variables. These results suggest that cultural ecology is related to children's JA, thereby scaffolding initiation of social sharing cues between children and adults. JA plays a role in adjusting children's internal representations of their respective ecological environment.

A negativity bias for ambiguous facial-expression valence during childhood: converging evidence from behavior and facial corrugator muscle responses

Interpretations of facial expressions with ambiguous valence, such as surprised (which can be perceived as having positive or negative valence), reveal individual differences in positivity-negativity biases. Negative interpretations are first and fast, but this initial negativity default can be overridden by regulatory control processes that result in positive interpretations. We tested the initial negativity hypothesis by examining positivity-negativity biases during development. We hypothesized that during childhood, the default negativity mode would be more evident than in adulthood and, as a group, children would show a negativity bias when processing ambiguous facial expressions. We examined ratings of two ambiguous expressions, surprised and neutral expressions, from childhood through adolescence and recorded facial corrugator muscle activity, a physiological index of negative appraisals. Surprised faces were rated as conveying clear negative affect by younger participants as indexed by fast RTs and negative ratings, and corrugator data showed a corresponding increase in activity to surprised faces. By adolescence, positive ratings of surprised faces became more frequent and RTs slowed, suggesting that surprised faces were perceived as having more ambiguous meaning. Accordingly, corrugator activity also decreased during adolescence. Neutral faces also produced negative ratings by children, but were also rated as conveying negative affect by older participants. Accordingly, neutral faces also elicited high corrugator activity that was similar to that elicited by negative expressions. These data show that early in life, ambiguous facial expressions are perceived as conveying negative meaning, adding support for an initial-negativity hypothesis.

Withholding response in the face of a smile: age-related differences in prefrontal sensitivity to Nogo cues following happy and angry faces

The modulation of control processes by stimulus salience, as well as associated neural activation, changes over development. We investigated age-related differences in the influence of facial emotion on brain activation when an action had to be withheld, focusing on a developmental period characterized by rapid social-emotional and cognitive change. Groups of kindergarten and young school-aged children and a group of young adults performed a modified Go/Nogo task. Response cues were preceded by happy or angry faces. After controlling for task performance, left orbitofrontal regions discriminated trials with happy vs. angry faces in children but not in adults when a response was withheld, and this effect decreased parametrically with age group. Age-related changes in prefrontal responsiveness to facial expression were not observed when an action was required, nor did this region show age-related activation changes with the demand to withhold a response in general. Such results reveal age-related differences in prefrontal activation that are specific to stimulus valence and depend on the action required.

The timing of educational investment: a neuroscientific perspective

Economic models of investment in human capital sometimes refer to neuroscience as a means to support their underlying assumptions regarding human development. These assumptions have a crucial influence on the policy implications the models generate. We review the extent to which the neuroscience of development can be used to support a "learning begets learning" principle of human capital accumulation. We conclude that, although early neural development can be considered as foundational, it cannot be considered as a unitary phenomenon that proceeds in continuous fashion. Furthermore, the concept of the sensitive period, which is often used associated with the principle, suggests benefits of investment depend upon an individual's circumstances and developmental history, and particularly whether this can be classified as normal. A more recent model of investment has involved two different types of abilities, with outcomes demonstrating the value of including more sophisticated assumptions about human development. We conclude that, while current discussions of policy would benefit from a more careful interpretation of existing models, the potential for future work combining modern neuroscientific understanding with economic theory is considerable.

Neural circuitry underlying affective response to peer feedback in adolescence

Peer feedback affects adolescents' behaviors, cognitions and emotions. We examined neural circuitry underlying adolescents' emotional response to peer feedback using a functional neuroimaging paradigm whereby, 36 adolescents (aged 9-17 years) believed they would interact with unknown peers postscan. Neural activity was expected to vary based on adolescents' perceptions of peers and feedback type. Ventrolateral prefrontal cortex (vlPFC) activity was found when adolescents indicated how they felt following feedback (acceptance or rejection) from peers of low vs high interest. Greater activation in both cortical (e.g. superior temporal gyrus, insula, anterior cingulate) and subcortical (e.g. striatum, thalamus) regions emerged in response to acceptance vs rejection feedback. Response to acceptance also varied by age and gender in similar regions (e.g. superior temporal gyrus, fusiform, insula), with greater age-related increases in activation to acceptance vs rejection for females than males. Affective response to rejection vs acceptance did not yield significantly greater neural activity in any region. vlPFC response suggests cognitive flexibility in reappraising initial perceptions of peers following feedback. Striatal response suggests that acceptance is a potent social reward for adolescents, an interpretation supported by more positive self-reported affective response to acceptance than rejection from high- but not low-interest peers.