A preliminary study of orbitofrontal activation and hypersociability in Williams Syndrome

The social phenotype associated with Wiedemann-Steiner syndrome: Autistic traits juxtaposed with high social drive and prosociality

The aim of this study was to provide a descriptive overview of the social characteristics associated with Wiedemann-Steiner syndrome (WSS). A total of 24 parents of children/adults with WSS (11F, mean age = 12.94 years, SD = 8.00) completed the Social Responsiveness Scale 2nd Edition (SRS-2); Colorado Learning Difficulties Questionnaire (CLDQ) and Strengths and Difficulties Questionnaire (SDQ). Almost half our sample reported a diagnosis of autism spectrum disorder (ASD) and 70% had intellectual disability. On the SDQ, over 90% of participants were rated in borderline/clinical ranges in Peer Problems, yet the majority fell within normal limits in Prosocial Behaviors. Most fell in the moderate/severe difficulties ranges across SRS-2 Social Cognition, Communication, and Restricted/Repetitive Behaviors scales (all >70%); whereas substantially less participants met these ranges for deficits in Social Awareness (50%) and Social Motivation (33.33%). A pattern of relatively strong prosocial skills and social drive in the context of difficulties with inflexible behaviors, social cognition, and communication was observed, regardless of gender, ASD or intellectual disability diagnosis. The social phenotype associated with WSS is characterized by some autistic features paired with unusually high social motivation and prosocial tendencies.

Adolescent Parvalbumin Expression in the Left Orbitofrontal Cortex Shapes Sociability in Female Mice

The adolescent social experience is essential for the maturation of the prefrontal cortex in mammalian species. However, it still needs to be determined which cortical circuits mature with such experience and how it shapes adult social behaviors in a sex-specific manner. Here, we examined social-approaching behaviors in male and female mice after postweaning social isolation (PWSI), which deprives social experience during adolescence. We found that the PWSI, particularly isolation during late adolescence, caused an abnormal increase in social approaches (hypersociability) only in female mice. We further found that the PWSI female mice showed reduced parvalbumin (PV) expression in the left orbitofrontal cortex (OFCL). When we measured neural activity in the female OFCL, a substantial number of neurons showed higher activity when mice sniffed other mice (social sniffing) than when they sniffed an object (object sniffing). Interestingly, the PWSI significantly reduced both the number of activated neurons and the activity level during social sniffing in female mice. Similarly, the CRISPR/Cas9-mediated knockdown of PV in the OFCL during late adolescence enhanced sociability and reduced the social sniffing-induced activity in adult female mice via decreased excitability of PV+ neurons and reduced synaptic inhibition in the OFCL Moreover, optogenetic activation of excitatory neurons or optogenetic inhibition of PV+ neurons in the OFCL enhanced sociability in female mice. Our data demonstrate that the adolescent social experience is critical for the maturation of PV+ inhibitory circuits in the OFCL; this maturation shapes female social behavior via enhancing social representation in the OFCL SIGNIFICANCE STATEMENT Adolescent social isolation often changes adult social behaviors in mammals. Yet, we do not fully understand the sex-specific effects of social isolation and the brain areas and circuits that mediate such changes. Here, we found that adolescent social isolation causes three abnormal phenotypes in female but not male mice: hypersociability, decreased PV+ neurons in the left orbitofrontal cortex (OFCL), and decreased socially evoked activity in the OFCL Moreover, parvalbumin (PV) deletion in the OFCL in vivo caused the same phenotypes in female mice by increasing excitation compared with inhibition within the OFCL Our data suggest that adolescent social experience is required for PV maturation in the OFCL, which is critical for evoking OFCL activity that shapes social behaviors in female mice.

Neuroanatomical correlates of social approach in Williams Syndrome and down syndrome

Individuals with Williams Syndrome (WS) or Downs Syndrome (DS) are often described as hypersociable, friendly and overly trusting of others. This hypersociability is a major concern for parents/caregivers due to the associated increased risk of exploitation and victimisation. Two brain regions - the amygdala and the orbitofrontal cortex (OFC) - have been implicated in driving this hypersociability in WS, and in the general population and have associations with emotional evaluation, threat detection and social motivation. However, there has been little neuroimaging research on this topic, especially in DS, to date. The aim of the present study was to investigate the potential neuroanatomical and neuropsychological correlates of hypersociability in WS and DS. Twelve individuals with WS (M = 22 years of age) and eleven individuals with DS (M = 26 years of age) completed a neuropsychological battery of executive functioning and social measures, including informant ratings on an ecologically measure of social approach. Clinical groups and twelve typically developing controls (M = 23 years) underwent a magnetic resonance imaging scan to investigate volumetric differences in the OFC and the amygdala. As expected, WS individuals displayed the highest overall social approach, especially in relation to need to approach strangers and drive to interact with strangers, as well as inappropriate/overfriendly behaviours. Both groups rated similarly in terms of social trust and unconditional positive regard. Emotion recognition abilities were similar across groups, with the DS group displaying some difficulties with negative emotions (especially anger). Inhibition and flexibility were similarly impaired across WS and DS. Compared to neurotypical controls, the DS group showed increased amygdala volumes bilaterally, while the WS group showed an enlarged right medial OFC. Approach ratings were significantly correlated with left amygdala and medial and left lateral OFC volumes in WS, and with these same regions bilaterally in DS. Results provide potential biological explanations for the hypersociability seen in WS and DS. Future research should focus on other potential neural correlates, as well as potential genetic and hormonal contributions to approach.

Emotional modulation of episodic memory in children and adolescents with Williams-Beuren syndrome

Children and adolescents with Williams-Beuren syndrome (WBS) have been described as having specific memory abilities and emotional reactivity. Although it is well established in the literature that emotion can enhance memory, no such studies have been undertaken in individuals with WBS. In three experiments, the present study tested whether the negative or positive emotional valence of stimuli can influence verbal, visual and visuo-spatial memory by specifically evaluating two memory components: item and associative memory. Sixteen 8- to 18-year-old individuals with WBS performed the first two experiments and, among them, twelve participated in the third. They were compared to equivalent groups of typically developing control children. Participants completed intentional-encoding tasks followed by immediate item recognition, associative recall or item recall tasks. Event-related potential measures during encoding and recognition of pictures were also added in the third experiment. Results demonstrated, for the first time, effects of emotions on visual item memory and visuo-spatial associative memory in individuals with WBS, that were similar to those observed in typically developing children. By combining behavioral and neural measures, our study provides new knowledge of the interaction between emotion and memory in WBS individuals, which seems to be unaffected by their atypical development.

Autism and Williams syndrome: truly mirror conditions in the socio-cognitive domain?

Autism Spectrum Disorders (ASD) and Williams Syndrome (WS) are frequently characterized as mirror conditions in the socio-cognitive domain, with ASD entailing restrictive social interests and with WS exhibiting hypersociability. In this review paper, we examine in detail the strong points and deficits of people with ASD or WS in the socio-cognitive domain and show that both conditions also share some common features. Moreover, we explore the neurobiological basis of the social profile of ASD and WS and found a similar mixture of common affected areas and condition-specific impaired regions. We discuss these findings under the hypothesis of a continuum of the socio-cognitive abilities in humans.

Extending the positive bias in Williams syndrome: The influence of biographical information on attention allocation

There is evidence that individuals with Williams syndrome (WS) show an attention bias toward positive social-perceptual (happy) faces. Research has not yet considered whether this attention bias extends beyond social-perceptual stimuli to perceptually neutral stimuli that are paired with positive (trustworthy) biographical information. Fourteen participants with WS (mean age = 21 years, 1 month) learned to associate perceptually neutral faces with trustworthy (positive), neutral, or untrustworthy (negative) biographical information, before completing a dot-probe task where the same biographical faces were presented. The performance of the WS group was compared to two typically developing control groups, individually matched to the WS individuals on chronological age and mental age, respectively. No between-group bias toward untrustworthy characters was observed. The WS group displayed a selective attention bias toward trustworthy characters compared to both control groups (who did not show such a bias). Results support previous findings that indicate WS individuals show a preference for positive social-perceptual stimuli (happy faces) at the neurological, physiological, and attentional levels. The current findings extend this work to include a "top-down" positive bias. The implications of a positive bias that extends beyond social-perceptual stimuli (or "bottom-up" processes) in this syndrome are discussed.

Cognitive, Behavioral, and Adaptive Profiles in Williams Syndrome With and Without Loss of GTF2IRD2

Williams syndrome (WS) is a neurodevelopmental disorder that results from a heterozygous microdeletion on chromosome 7q11.23. Most of the time, the affected region contains ~1.5 Mb of sequence encoding approximately 24 genes. Some 5-8% of patients with WS have a deletion exceeding 1.8 Mb, thereby affecting two additional genes, including GTF2IRD2. Currently, there is no consensus regarding the implications of GTF2IRD2 loss for the neuropsychological phenotype of WS patients.

OBJECTIVES

The present study aimed to identify the role of GTF2IRD2 in the cognitive, behavioral, and adaptive profile of WS patients.

METHODS

Twelve patients diagnosed with WS participated, four with GTF2IRD2 deletion (atypical WS group), and eight without this deletion (typical WS group). The age range of both groups was 7-18 years old. Each patient's 7q11.23 deletion scope was determined by chromosomal microarray analysis. Cognitive, behavioral, and adaptive abilities were assessed with a battery of neuropsychological tests.

RESULTS

Compared with the typical WS group, the atypical WS patients with GTF2IRD2 deletion had more impaired visuospatial abilities and more significant behavioral problems, mainly related to the construct of social cognition.

CONCLUSIONS

These findings provide new evidence regarding the influence of the GTF2IRD2 gene on the severity of behavioral symptoms of WS related to social cognition and certain visuospatial abilities. (JINS, 2018, 24, 896-904).

Understanding Strategic Information Use During Emotional Expression Judgments in Williams Syndrome

Detailed analysis of expression judgments in Williams syndrome reveals that successful emotion categorization need not reflect "classic" information processing strategies. These individuals draw upon a distinct set of featural details to identify happy and fearful faces that differ from those used by typically developing comparison groups: children and adults. The diagnostic visual information is also notably less interlinked in Williams syndrome, consistent with reports of diminished processing of configural information during face identity judgments. These results prompt reconsideration of typical models of face expertise by revealing that an age-appropriate profile of expression performance can be achieved via alternative routes.

Attention allocation to facial expressions of emotion among persons with Williams and Down syndromes

Individuals with Williams syndrome and those with Down syndrome are both characterized by heightened social interest, although the manifestation is not always similar. Using a dot-probe task, we examined one possible source of difference: allocation of attention to facial expressions of emotion. Thirteen individuals with Williams syndrome (mean age = 19.2 years, range = 10-28.6), 20 with Down syndrome (mean age = 18.8 years, range = 12.1-26.3), and 19 typically developing children participated. The groups were matched for mental age (mean = 5.8 years). None of the groups displayed a bias to angry faces. The participants with Williams syndrome showed a selective bias toward happy faces, whereas the participants with Down syndrome behaved similarly to the typically developing participants with no such bias. Homogeneity in the direction of bias was markedly highest in the Williams syndrome group whose bias appeared to result from enhanced attention capture. They appeared to rapidly and selectively allocate attention toward positive facial expressions. The complexity of social approach behavior and the need to explore other aspects of cognition that may be implicated in this behavior in both syndromes is discussed.

Processing of stimulus content but not of emotional valence is altered in persons with Williams syndrome

BACKGROUND

Individuals with Williams syndrome (WS) exhibit hypersociability and may respond atypically to emotional information in social and nonsocial stimuli. It is not yet clear whether these difficulties are specific to emotional content or stimulus type. This study examined the neural processes supporting social and emotional information processing in WS.

METHOD

Visual event-related potentials were recorded in 19 adults with WS and 10 typical peers during a picture-viewing task requiring detection of smiling faces among other social and nonsocial images with positive and negative emotional content.

RESULTS

The participant groups were not significantly different in affective processing of positive and negative stimuli and perceived faces as different from nonsocial images. Participants with WS showed subtle differences in face-specific perceptual processes (e.g. face inversion, N170 lateralisation), suggesting a more feature-based processing. They also demonstrated reduced attention and arousal modulation (P3, late positive potential) in response to faces vs. nonsocial images. These differences were independent of intelligence quotient.

CONCLUSIONS

There was no evidence of greater than typical perceptual, attentional or affective processing of social information in WS. The results support the idea that altered face perception processes and not the increased salience of social stimuli or difficulties with emotion discrimination may contribute to the hypersocial phenotype in WS.

Facial emotion processing in patients with social anxiety disorder and Williams-Beuren syndrome: an fMRI study

BACKGROUND

Social anxiety disorder (SAD) and Williams-Beuren syndrome (WBS) are 2 conditions with major differences in terms of genetics, development and cognitive profiles. Both conditions are associated with compromised abilities in overlapping areas, including social approach, processing of social emotional cues and gaze behaviour, and to some extent they are associated with opposite behaviours in these domains. We examined common and distinct patterns of brain activation during a facial emotion processing paradigm in patients with SAD and WBS.

METHODS

We examined patients with SAD and WBS and healthy controls matched by age and laterality using functional MRI during the processing of happy, fearful and angry faces.

RESULTS

We included 20 patients with SAD and 20 with WBS as well as 20 matched controls in our study. Patients with SAD and WBS did not differ in the pattern of limbic activation. We observed differences in early visual areas of the face processing network in patients with WBS and differences in the cortical prefrontal regions involved in the top-down regulation of anxiety and in the fusiform gyrus for patients with SAD. Compared with those in the SAD and control groups, participants in the WBS group did not activate the right lateral inferior occipital cortex. In addition, compared with controls, patients with WBS hypoactivated the posterior primary visual cortex and showed significantly less deactivation in the right temporal operculum. Participants in the SAD group showed decreased prefrontal activation compared with those in the WBS and control groups. In addition, compared with controls, participants with SAD showed decreased fusiform activation. Participants with SAD and WBS also differed in the pattern of activation in the superior temporal gyrus, a region that has been linked to gaze processing.

LIMITATIONS

The results observed in the WBS group are limited by the IQ of the WBS sample; however, the specificity of findings suggests that the pattern of brain activation observed for WBS is more likely to reflect a neurobiological substrate rather than intellectual impairment per se.

CONCLUSION

Patients with SAD and WBS showed common and specific patterns of brain activation. Our results highlight the role of cortical regions during facial emotion processing in individuals with SAD and WBS.

Neurobiology of social behavior abnormalities in autism and Williams syndrome

Social behavior is a basic behavior mediated by multiple brain regions and neural circuits, and is crucial for the survival and development of animals and humans. Two neuropsychiatric disorders that have prominent social behavior abnormalities are autism spectrum disorders (ASD), which is characterized mainly by hyposociability, and Williams syndrome (WS), whose subjects exhibit hypersociability. Here we review the unique properties of social behavior in ASD and WS, and discuss the major theories in social behavior in the context of these disorders. We conclude with a discussion of the research questions needing further exploration to enhance our understanding of social behavior abnormalities.

Promoting social plasticity in developmental disorders with non-invasive brain stimulation techniques

Being socially connected directly impacts our basic needs and survival. People with deficits in social cognition might exhibit abnormal behaviors and face many challenges in our highly social-dependent world. These challenges and limitations are associated with a substantial economical and subjective impact. As many conditions where social cognition is affected are highly prevalent, more treatments have to be developed. Based on recent research, we review studies where non-invasive neuromodulatory techniques have been used to promote Social Plasticity in developmental disorders. We focused on three populations where non-invasive brain stimulation seems to be a promising approach in inducing social plasticity: Schizophrenia, Autism Spectrum Disorder (ASD) and Williams Syndrome (WS). There are still very few studies directly evaluating the effects of transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS) in the social cognition of these populations. However, when considering the promising preliminary evidences presented in this review and the limited amount of clinical interventions available for treating social cognition deficits in these populations today, it is clear that the social neuroscientist arsenal may profit from non-invasive brain stimulation techniques for rehabilitation and promotion of social plasticity.

Structural integrity of the limbic-prefrontal connection: Neuropathological correlates of anxiety in Williams syndrome

Williams syndrome (WS) is a genetic condition characterized by a hypersocial personality and desire to form close relationships, juxtaposed with significant anxieties of nonsocial events. The neural underpinnings of anxiety in individuals with WS are currently unknown. Aberrations in the anatomical and microstructural integrity of the uncinate fasciculus (UF) have been recently implicated in social and generalized anxiety disorders. Based on these findings, we tested the hypothesis that the reported anxieties in individuals with WS share similar neuropathological correlates. Toward this end, diffusion tensor imaging (DTI) methods were employed to examine the microstructural integrity (fractional anisotropy, mean diffusivity, longitudinal diffusivity) of the UF in 18 WS and 15 typically developing adults (TD). Anxiety and sociability questionnaires were administered to determine associations with DTI indices of UF across groups. Results revealed comparable white matter integrity of the UF across groups, yet elevated subjective experience of anxiety in those with WS. Additionally, sociability and UF microstructural properties were dissociated across both groups. Whereas no relationships were found between DTI indices and anxiety in TD participants, strong negative associations were observed between these constructs in individuals with WS. Findings indicated that increased anxiety manifested by individuals with WS was associated with DTI measures of the UF and may signal structural or possibly physiological aberration involving this tract within the prefrontal-temporal network.

Cortical thickness and prosocial behavior in school-age children: A population-based MRI study

Prosocial behavior plays an important role in establishing and maintaining relationships with others and thus may have important developmental implications. This study examines the association between cortical thickness and prosocial behavior in a population-based sample of 6- to 9-year-old children. The present study was embedded within the Generation R Study. Magnetic resonance scans were acquired from 464 children whose parents had completed the prosocial scale of the Strengths and Difficulties Questionnaire. To study the association between cortical thickness and prosocial behavior, we performed whole-brain surface-based analyses. Prosocial behavior was related to a thicker cortex in a cluster that covers part of the left superior frontal and rostral middle frontal cortex (p < .001). Gender moderated the association between prosocial behavior and cortical thickness in a cluster including the right rostral middle frontal and superior frontal cortex (p < .001) as well as in a cluster covering the right superior parietal cortex, cuneus, and precuneus (p < .001). Our results suggest that prosocial behavior is associated with cortical thickness in regions related to theory of mind (superior frontal cortex, rostral middle frontal cortex cuneus, and precuneus) and inhibitory control (superior frontal and rostral middle frontal cortex).

Frontal asymmetry index in Williams syndrome: Evidence for altered emotional brain circuitry?

Asymmetrical frontal electroencephalography (EEG) activity is associated with motivational neural systems of approach/withdrawal behaviors. Greater left frontal EEG has been linked to increased appetitive tendencies whereas increased right frontal activity is related to the activation of avoidance mechanisms. Williams syndrome (WS) is a genetic condition characterized by a highly sociable personality manifested by a propensity to approach strangers and decreased social fear. Consequently, the current study was designed to investigate the frontal cortical activity during resting state, indexed by relative alpha power, in adults with WS as compared to typically developing (TD) controls, and a subgroup of TD extraverts. Results indicated that participants with WS produced attenuated left frontal activity relative to TD peers, or TD extraverts in particular; yet, no groups differed in their degree of right frontal activity. Finally, while both TD group and the extravert subset showed trends of greater left over right frontal activity, the WS participants demonstrated opposing effect of increased right over left frontal EEG. Importantly, individuals with WS produced deviating frontal activity patterns compared to TD extraverts despite exhibiting common social-affiliative tendencies, underscoring that neural mechanisms that give rise to extraversion in WS may not function similarly to those subserving this personality trait expressed in TD.

Altered microstructure within social-cognitive brain networks during childhood in Williams syndrome

Williams syndrome (WS) is a neurodevelopmental condition caused by a hemizygous deletion of ∼26-28 genes on chromosome 7q11.23. WS is associated with a distinctive pattern of social cognition. Accordingly, neuroimaging studies show that WS is associated with structural alterations of key brain regions involved in social cognition during adulthood. However, very little is currently known regarding the neuroanatomical structure of social cognitive brain networks during childhood in WS. This study used diffusion tensor imaging to investigate the structural integrity of a specific set of white matter pathways (inferior fronto-occipital fasciculus [IFOF] and uncinate fasciculus [UF]) and associated brain regions [fusiform gyrus (FG), amygdala, hippocampus, medial orbitofrontal gyrus (MOG)] known to be involved in social cognition in children with WS and a typically developing (TD) control group. Children with WS exhibited higher fractional anisotropy (FA) and axial diffusivity values and lower radial diffusivity and apparent diffusion coefficient (ADC) values within the IFOF and UF, higher FA values within the FG, amygdala, and hippocampus and lower ADC values within the FG and MOG compared to controls. These findings provide evidence that the WS genetic deletion affects the development of key white matter pathways and brain regions important for social cognition.

Using novel control groups to dissect the amygdala's role in Williams syndrome

Williams syndrome is a neurodevelopmental disorder with an intriguing behavioral phenotype-hypersociability combined with significant non-social fears. Previous studies have demonstrated abnormalities in amygdala function in individuals with Williams syndrome compared to typically-developing controls. However, it remains unclear whether the findings are related to the atypical neurodevelopment of Williams syndrome, or are also associated with behavioral traits at the extreme end of a normal continuum. We used functional magnetic resonance imaging (fMRI) to compare amygdala blood-oxygenation-level-dependent (BOLD) responses to non-social and social images in individuals with Williams syndrome compared to either individuals with inhibited temperament (high non-social fear) or individuals with uninhibited temperament (high sociability). Individuals with Williams syndrome had larger amygdala BOLD responses when viewing the non-social fear images than the inhibited temperament control group. In contrast, when viewing both fear and neutral social images, individuals with Williams syndrome did not show smaller amygdala BOLD responses relative to the uninhibited temperament control group, but instead had amygdala responses proportionate to their sociability. These results suggest heightened amygdala response to non-social fear images is characteristic of WS, whereas, variability in amygdala response to social fear images is proportionate to, and might be explained by, levels of trait sociability.

The effect of intellectual ability on functional activation in a neurodevelopmental disorder: preliminary evidence from multiple fMRI studies in Williams syndrome

Background

Williams syndrome (WS) is a rare genetic disorder caused by the deletion of approximately 25 genes at 7q11.23 that involves mild to moderate intellectual disability (ID). When using functional magnetic resonance imaging (fMRI) to compare individuals with ID to typically developing individuals, there is a possibility that differences in IQ contribute to between-group differences in BOLD signal. If IQ is correlated with BOLD signal, then group-level analyses should adjust for IQ, or else IQ should be matched between groups. If, however, IQ is not correlated with BOLD signal, no such adjustment or criteria for matching (and exclusion) based on IQ is necessary.

Methods

In this study, we aimed to test this hypothesis systematically using four extant fMRI datasets in WS. Participants included 29 adult subjects with WS (17 men) demonstrating a wide range of standardized IQ scores (composite IQ mean = 67, SD = 17.2). We extracted average BOLD activation for both cognitive and task-specific anatomically defined regions of interest (ROIs) in each individual and correlated BOLD with composite IQ scores, verbal IQ scores and non-verbal IQ scores in Spearman rank correlation tests.

Results

Of the 312 correlations performed, only six correlations (2%) in four ROIs reached statistical significance at a P value < 0.01, but none survived correction for multiple testing. All six correlations were positive. Therefore, none supports the hypothesis that IQ is negatively correlated with BOLD response.

Conclusions

These data suggest that the inclusion of subjects with below normal IQ does not introduce a confounding factor, at least for some types of fMRI studies with low cognitive load. By including subjects who are representative of IQ range for the targeted disorder, findings are more likely to generalize to that population.

Conceptualizing neurodevelopmental disorders through a mechanistic understanding of fragile X syndrome and Williams syndrome

PURPOSE OF REVIEW

The overarching goal of this review is to compare and contrast the cognitive-behavioral features of fragile X syndrome (FraX) and Williams syndrome and to review the putative neural and molecular underpinnings of these features. Information is presented in a framework that provides guiding principles for conceptualizing gene-brain-behavior associations in neurodevelopmental disorders.

RECENT FINDINGS

Abnormalities, in particular cognitive-behavioral domains with similarities in underlying neurodevelopmental correlates, occur in both FraX and Williams syndrome including aberrant frontostriatal pathways leading to executive function deficits, and magnocellular/dorsal visual stream, superior parietal lobe, inferior parietal lobe, and postcentral gyrus abnormalities contributing to deficits in visuospatial function. Compelling cognitive-behavioral and neurodevelopmental contrasts also exist in these two disorders, for example, aberrant amygdala and fusiform cortex structure and function occurring in the context of contrasting social behavioral phenotypes, and temporal cortical and cerebellar abnormalities potentially underlying differences in language function. Abnormal dendritic development is a shared neurodevelopmental morphologic feature between FraX and Williams syndrome. Commonalities in molecular machinery and processes across FraX and Williams syndrome occur as well - microRNAs involved in translational regulation of major synaptic proteins; scaffolding proteins in excitatory synapses; and proteins involved in axonal development.

SUMMARY

Although the genetic variations leading to FraX and Williams syndrome are different, important similarities and contrasts in the phenotype, neurocircuitry, molecular machinery, and cellular processes in these two disorders allow for a unique approach to conceptualizing gene-brain-behavior links occurring in neurodevelopmental disorders.

Reward circuitry dysfunction in psychiatric and neurodevelopmental disorders and genetic syndromes: animal models and clinical findings

This review summarizes evidence of dysregulated reward circuitry function in a range of neurodevelopmental and psychiatric disorders and genetic syndromes. First, the contribution of identifying a core mechanistic process across disparate disorders to disease classification is discussed, followed by a review of the neurobiology of reward circuitry. We next consider preclinical animal models and clinical evidence of reward-pathway dysfunction in a range of disorders, including psychiatric disorders (i.e., substance-use disorders, affective disorders, eating disorders, and obsessive compulsive disorders), neurodevelopmental disorders (i.e., schizophrenia, attention-deficit/hyperactivity disorder, autism spectrum disorders, Tourette's syndrome, conduct disorder/oppositional defiant disorder), and genetic syndromes (i.e., Fragile X syndrome, Prader-Willi syndrome, Williams syndrome, Angelman syndrome, and Rett syndrome). We also provide brief overviews of effective psychopharmacologic agents that have an effect on the dopamine system in these disorders. This review concludes with methodological considerations for future research designed to more clearly probe reward-circuitry dysfunction, with the ultimate goal of improved intervention strategies.

Social brain development in williams syndrome: the current status and directions for future research

Williams syndrome (WS) is a neurodevelopmental condition that occurs as a result of a contiguous deletion of ∼26–28 genes on chromosome 7q11.23. WS is often associated with a distinctive social phenotype characterized by an increased affinity toward processing faces, reduced sensitivity to fear related social stimuli and a reduced ability to form concrete social relationships. Understanding the biological mechanisms that underlie the social phenotype in WS may elucidate genetic and neural factors influencing the typical development of the social brain. In this article, we review available studies investigating the social phenotype of WS throughout development and neuroimaging studies investigating brain structure and function as related to social and emotional functioning in this condition. This review makes an important contribution by highlighting several neuro-behavioral mechanisms that may be a cause or a consequence of atypical social development in WS. In particular, we discuss how distinctive social behaviors in WS may be associated with alterations or delays in the cortical representation of faces, connectivity within the ventral stream, structure and function of the amygdala and how long- and short-range connections develop within the brain. We integrate research on typical brain development and from existing behavioral and neuroimaging research on WS. We conclude with a discussion of how genetic and environmental factors might interact to influence social brain development in WS and how future neuroimaging and behavioral research can further elucidate social brain development in WS. Lastly, we describe how ongoing studies may translate to improved social developmental outcomes for individuals with WS.

Behavioral outcomes of late-onset or early-onset orbital frontal cortex (areas 11/13) lesions in rhesus monkeys

The orbital frontal cortex (OFC) has been implicated in a number of psychiatric disorders, including depression, anxiety, phobia, and obsessive-compulsive disorder. Thus, a better understanding of its functions will likely provide critical information to understand the specific behavioral and cognitive processes affected in these human disorders. In recent years, a growing number of studies have provided evidence for anatomical and functional differentiation within the OFC. Here we discuss the effects of selective OFC (areas 11/13) lesions on social behavior, emotional regulation, and behavioral adaptation. Damage to these specific OFC subfields in adult monkeys resulted in profound changes in the flexible modulation of responses guided by reward value that could explain the poor fear regulation and disturbed social interactions observed in the same animals. A similar pattern of results was found when the OFC lesions were done in infancy. Thus, in monkeys, self-regulation abilities mediated by OFC areas 11/13 emerge from midinfancy through adolescence.