High-throughput functional analysis of autism genes in zebrafish identifies convergence in dopaminergic and neuroimmune pathways.

Advancing from gene discovery in autism spectrum disorders (ASDs) to the identification of biologically relevant mechanisms remains a central challenge. Here, we perform parallel in vivo functional analysis of 10 ASD genes at the behavioral, structural, and circuit levels in zebrafish mutants, revealing both unique and overlapping effects of gene loss of function. Whole-brain mapping identifies the forebrain and cerebellum as the most significant contributors to brain size differences, while regions involved in sensory-motor control, particularly dopaminergic regions, are associated with altered baseline brain activity. Finally, we show a global increase in microglia resulting from ASD gene loss of function in select mutants, implicating neuroimmune dysfunction as a key pathway relevant to ASD biology.

Reduced Amygdala-Prefrontal Functional Connectivity in Children With Autism Spectrum Disorder and Co-occurring Disruptive Behavior.

BACKGROUND: Disruptive behaviors are prevalent in children with autism spectrum disorder (ASD) and often cause substantial impairments. However, the underlying neural mechanisms of disruptive behaviors remain poorly understood in ASD. In children without ASD, disruptive behavior is associated with amygdala hyperactivity and reduced connectivity with the ventrolateral prefrontal cortex (vlPFC). This study examined amygdala reactivity and connectivity in children with ASD with and without co-occurring disruptive behavior disorders. We also investigated differential contributions of externalizing behaviors and callous-unemotional traits to variance in amygdala connectivity and reactivity. METHODS: This cross-sectional study involved behavioral assessments and neuroimaging in three groups of children 8 to 16 years of age: 18 children had ASD and disruptive behavior, 20 children had ASD without disruptive behavior, and 19 children were typically developing control participants matched for age, gender, and IQ. During functional magnetic resonance imaging, participants completed an emotion perception task of fearful versus calm faces. Task-specific changes in amygdala reactivity and connectivity were examined using whole-brain, psychophysiological interaction, and multiple regression analyses. RESULTS: Children with ASD and disruptive behavior showed reduced amygdala-vlPFC connectivity compared with children with ASD without disruptive behavior. Externalizing behaviors and callous-unemotional traits were associated with amygdala reactivity to fearful faces in children with ASD after controlling for suppressor effects. CONCLUSIONS: Reduced amygdala-vlPFC connectivity during fear processing may differentiate children with ASD and disruptive behavior from children with ASD without disruptive behavior. The presence of callous-unemotional traits may have implications for identifying differential patterns of amygdala activity associated with increased risk of aggression in ASD. These findings suggest a neural mechanism of emotion dysregulation associated with disruptive behavior in children with ASD.

Neural Mechanisms of Cognitive-Behavioral Therapy for Aggression in Children and Adolescents: Design of a Randomized Controlled Trial Within the National Institute for Mental Health Research Domain Criteria Construct of Frustrative Non-Reward.

OBJECTIVE: We present the rationale and design of a randomized controlled trial of cognitive-behavioral therapy (CBT) for aggression in children and adolescents, which is conducted in response to the National Institute of Mental Health (NIMH) Research Domain Criteria (RDoC) approach initiative. Specifically, the study is focused on the brain-behavior associations within the RDoC construct of frustrative non-reward. On the behavioral level, this construct is defined by reactions elicited in response to withdrawal or prevention of reward, most notably reactive aggression. This study is designed to test the functional magnetic resonance (fMRI) and electrophysiological (EEG) correlates of aggression and its reduction after CBT. METHODS: Eighty children and adolescents with high levels of aggression across multiple traditional diagnostic categories, ages 8-16, will be randomly assigned to receive 12 sessions of CBT or 12 sessions of supportive psychotherapy. Clinical outcomes will be measured by the ratings of aggressive behavior collected at baseline, midpoint, and endpoint evaluations, and by the Improvement Score of the Clinical Global Impressions Scale assigned by an independent evaluator (blinded rater). Subjects will also perform a frustration-induction Go-NoGo task and a task of emotional face perception during fMRI scanning and EEG recording at baseline and endpoint. RESULTS: Consistent with the NIMH strategic research priorities, if functional neuroimaging and EEG variables can identify subjects who respond to CBT for aggression, this can provide a neuroscience-based classification scheme that will improve treatment outcomes for children and adolescents with aggressive behavior. CONCLUSIONS: Demonstrating that a change in the key nodes of the emotion regulation circuitry is associated with a reduction of reactive aggression will provide evidence to support the validity of the frustrative non-reward construct.

Oxytocin enhances brain function in children with autism.

Following intranasal administration of oxytocin (OT), we measured, via functional MRI, changes in brain activity during judgments of socially (Eyes) and nonsocially (Vehicles) meaningful pictures in 17 children with high-functioning autism spectrum disorder (ASD). OT increased activity in the striatum, the middle frontal gyrus, the medial prefrontal cortex, the right orbitofrontal cortex, and the left superior temporal sulcus. In the striatum, nucleus accumbens, left posterior superior temporal sulcus, and left premotor cortex, OT increased activity during social judgments and decreased activity during nonsocial judgments. Changes in salivary OT concentrations from baseline to 30 min postadministration were positively associated with increased activity in the right amygdala and orbitofrontal cortex during social vs. nonsocial judgments. OT may thus selectively have an impact on salience and hedonic evaluations of socially meaningful stimuli in children with ASD, and thereby facilitate social attunement. These findings further the development of a neurophysiological systems-level understanding of mechanisms by which OT may enhance social functioning in children with ASD.

Social, reward, and attention brain networks are involved when online bids for joint attention are met with congruent versus incongruent responses.

Joint attention (JA) is a cornerstone of adaptive human social functioning. Little functional magnetic resonance imaging (fMRI) research has examined, in interactive paradigms, neural activation underlying bids for JA, met with a congruent or an incongruent social response. We developed a highly naturalistic fMRI paradigm utilizing eye-tracking to create real-time, contingent social responses to participant-initiated JA. During congruent responses to JA bids, we observed increased activation in the right amygdala, the right fusiform gyrus, anterior and dorsal anterior cingulate cortices, striatum, ventral tegmental area, and posterior parietal cortices. Incongruent responses to JA bids elicited increased activity localized to the right temporoparietal junction (TPJ) and bilateral cerebellum. No differences in eye-gaze patterns were observed during congruent or incongruent trials. Our results highlight the importance of utilizing interactive fMRI paradigms in social neuroscience and the impact of congruency in recruiting integrated social, reward, and attention circuits for processing JA.