Amygdala subnuclei development in adolescents with autism spectrum disorder: Association with social communication and repetitive behaviors

Transcriptome analysis identifies an ASD-Like phenotype in oligodendrocytes and microglia from C58/J amygdala that is dependent on sex and sociability

BACKGROUND

Autism Spectrum Disorder (ASD) is a group of neurodevelopmental disorders with higher incidence in males and is characterized by atypical verbal/nonverbal communication, restricted interests that can be accompanied by repetitive behavior, and disturbances in social behavior. This study investigated brain mechanisms that contribute to sociability deficits and sex differences in an ASD animal model.

METHODS

Sociability was measured in C58/J and C57BL/6J mice using the 3-chamber social choice test. Bulk RNA-Seq and snRNA-Seq identified transcriptional changes in C58/J and C57BL/6J amygdala within which DMRseq was used to measure differentially methylated regions in amygdala.

RESULTS

C58/J mice displayed divergent social strata in the 3-chamber test. Transcriptional and pathway signatures revealed immune-related biological processes differ between C58/J and C57BL/6J amygdala. Hypermethylated and hypomethylated genes were identified in C58/J versus C57BL/6J amygdala. snRNA-Seq data in C58/J amygdala identified differential transcriptional signatures within oligodendrocytes and microglia characterized by increased ASD risk gene expression and predicted impaired myelination that was dependent on sex and sociability. RNA velocity, gene regulatory network, and cell communication analysis showed diminished oligodendrocyte/microglia differentiation. Findings were verified using Bulk RNA-Seq and demonstrated oxytocin's beneficial effects on myelin gene expression.

LIMITATIONS

Our findings are significant. However, limitations can be noted. The cellular mechanisms linking reduced oligodendrocyte differentiation and reduced myelination to an ASD phenotype in C58/J mice need further investigation. Additional snRNA-Seq and spatial studies would determine if effects in oligodendrocytes/microglia are unique to amygdala or if this occurs in other brain regions. Oxytocin's effects need further examination to understand its' potential as an ASD therapeutic.

CONCLUSIONS

Our work demonstrates the C58/J mouse model's utility in evaluating the influence of sex and sociability on the transcriptome in concomitant brain regions involved in ASD. Our single-nucleus transcriptome analysis elucidates potential pathological roles of oligodendrocytes and microglia in ASD. This investigation provides details regarding regulatory features disrupted in these cell types, including transcriptional gene dysregulation, aberrant cell differentiation, altered gene regulatory networks, and changes to key pathways that promote microglia/oligodendrocyte differentiation. Our studies provide insight into interactions between genetic risk and epigenetic processes associated with divergent affiliative behavior and lack of positive sociability.

Amygdala volumes and associations with socio-emotional competencies in preterm youth: cross-sectional and longitudinal data

BACKGROUND

Socio-emotional difficulties often result from very preterm (VPT) birth. The amygdala's developmental trajectory, including its nuclei, has been recognized as a significant factor in observed difficulties. This study aims to assess the relationship between amygdala volume and socio-emotional competencies in VPT children and adolescents.

METHODS

Socio-emotional competencies were assessed, and amygdala volumes, including subnuclei, were extracted automatically from structural scans in a cross-sectional cohort of VPT (n = 75) and full-term (FT, n = 41) aged 6-14 years. Group differences in amygdala volumes were assessed using ANCOVA, and associations with socio-emotional competencies were studied using partial least squares correlation (PLSC). In a VPT subgroup, additional longitudinal data with amygdala volumes at term-equivalent age (TEA) were manually extracted, growth rates calculated, and associations with school-age socio-emotional competencies investigated using PLSC.

RESULTS

Using cross-sectional data at school-age, amygdala volumes displayed comparable developmental patterns between the VPT and the FT groups. Greater volumes were associated with more emotional regulation difficulties in VPT and lower affect recognition competencies in FT. In the longitudinal VPT subgroup, no significant associations were found between amygdala volume trajectory and socio-emotional competencies.

CONCLUSION

Although our findings suggest typical amygdala development after VPT birth, further research is necessary to elucidate the developmental trajectory of amygdala and the role of resilience factors.

IMPACT

In our cohort, amygdala volumes, including subnuclei, displayed comparable developmental trajectories between the very preterm and the full-term groups. Higher amygdala volumes at school-age were associated with higher emotional regulation difficulties in the very-preterm born group, and with lower affect recognition abilities in full-term born children and adolescents. In a subgroup of very-preterm children and adolescents followed from birth to school-age, no significant associations were found between amygdala volumes at term-equivalent age and socio-emotional competencies at school-age.

Strategic social decision making undergoes significant changes in typically developing and autistic early adolescents

Information sampling about others' trustworthiness prior to cooperation allows humans to minimize the risk of exploitation. Here, we examined whether early adolescence or preadolescence, a stage defined as in between childhood and adolescence, is a significant developmental period for strategic social decisions. We also sought to characterize differences between autistic children and their typically developing (TD) peers. TD (N = 48) and autistic (N = 56) 8- to 12-year-olds played an online information sampling trust game. While both groups adapted their information sampling and cooperation to the various trustworthiness levels of the trustees, groups differed in how age and social skills modulated task behavior. In the TD group social skills were a stronger overall predictor of task behavior. In the autistic group, age was a stronger predictor and interacted with social skills. Computational modeling revealed that both groups used the same heuristic information sampling strategy-albeit older TD children were more efficient as reflected by decreasing decision noise with age. Autistic children had lower prior beliefs about the trustee's trustworthiness compared to TD children. These lower priors indicate that children believed the trustees to be less trustworthy. Lower priors scaled with lower social skills across groups. Notably, groups did not differ in prior uncertainty, meaning that the priors of TD and autistic children were equally strong. Taken together, we found significant development in information sampling and cooperation in early adolescence and nuanced differences between TD and autistic children. Our study highlights the importance of deep phenotyping of children including clinical measures, behavioral experiments and computational modeling. RESEARCH HIGHLIGHTS: We specified how early adolescents with and without an autism diagnosis sampled information about their interaction partners and made cooperation decisions in a strategic game. Early adolescence is a significant developmental period for strategic decision making, marked by significant changes in information sampling efficiency and adaptivity to the partner's behavior. Autistic and non-autistic groups differed in how age and social skills modulated task behavior; in non-autistic children behavior was more indicative of overall social skills. Computational modeling revealed differences between autistic and non-autistic groups in their initial beliefs about cooperation partners; autistic children expected their partners to be less trustworthy.

Inhibitory dysfunction and social processing difficulties in autism: A comprehensive narrative review

The primary inhibitory neurotransmitter γ-aminobutyric acid (GABA) has a prominent role in regulating neural development and function, with disruption to GABAergic signalling linked to behavioural phenotypes associated with neurodevelopmental disorders, particularly autism. Such neurochemical disruption, likely resulting from diverse genetic and molecular mechanisms, particularly during early development, can subsequently affect the cellular balance of excitation and inhibition in neuronal circuits, which may account for the social processing difficulties observed in autism and related conditions. This comprehensive narrative review integrates diverse streams of research from several disciplines, including molecular neurobiology, genetics, epigenetics, and systems neuroscience. In so doing it aims to elucidate the relevance of inhibitory dysfunction to autism, with specific focus on social processing difficulties that represent a core feature of this disorder. Many of the social processing difficulties experienced in autism have been linked to higher levels of the excitatory neurotransmitter glutamate and/or lower levels of inhibitory GABA. While current therapeutic options for social difficulties in autism are largely limited to behavioural interventions, this review highlights the psychopharmacological studies that explore the utility of GABA modulation in alleviating such difficulties.

Valproate-induced murine autism spectrum disorder is associated with dysfunction of amygdala parvalbumin interneurons and downregulation of AMPK/SIRT1/PGC1α signaling

Autism spectrum disorder (ASD) is a neurodevelopmental condition that is characterized by difficulty in social behavior and restricted behaviors. Also, in ASD, several accompanying disorders such as anxiety are observed. Considering the important role of amygdala in the pathophysiology of ASD, the present study focused on the neuronal changes and it possible signaling pathway in amygdala. After prenatal exposure to valproate (VPA; 600 mg/kg, i.p, on embryonic day 12.5), amount of ROS, MMP, caspase-3 activity, AMPK, SIRT1 and PGC1α proteins, and parvalbumin interneurons in the amygdala were assessed following evaluation of ASD and anxiety-like behaviors. Amygdala analysis revealed ROS accumulation and decreased MMP in autistic rats. In addition, caspase-3 activation elevated and immunoreactivity for parvalbumin interneurons decreased. These were accompanied by anxiety and autistic-like behaviors in open field test, elevated zero maze and U-Shaped 2 Choice Field maze. Also, our data showed that in the valproate group, protein levels of AMPK, SIRT1 and PGC1α reduced. Collectively, our results indicate that prenatal exposure to valproate leads to anxiety and autistic-like behaviors, partly through its targeting amygdala parvalbumin interneurons dysfunction and this might be affected by disturbed AMPK/SIRT1/PGC1α signaling pathway.

Exploring the relationship between amygdala subnuclei volumes and cognitive performance in left-lateralized temporal lobe epilepsy with and without hippocampal sclerosis

Cognitive disruption is a debilitating comorbidity in Temporal Lobe Epilepsy (TLE). Despite recent advances, the amygdala is often neglected in studies that explore cognition in TLE. Amygdala subnuclei are differently engaged in TLE with hippocampal sclerosis (TLE-HS) compared to non-lesional TLE (TLE-MRIneg), with predominant atrophy in the first and increased volume in the latter. Herein, we aim to explore the relationship between the volumes of the amygdala and its substructures with respect to cognitive performances in a population of left-lateralized TLE with and without HS. Twenty-nine TLEs were recruited (14 TLE-HS; 15 TLE-MRIneg). After investigating the differences in the subcortical amygdalae and hippocampal volumes compared to a matched healthy control population, we explored the associations between the subnuclei of the amygdala and the hippocampal subfields with the cognitive scores in TLE patients, according to their etiology. In TLE-HS, a reduced volume of the basolateral and cortical amygdala complexes joined with whole hippocampal atrophy, was related to poorer scores in verbal memory tasks, while in TLE-MRIneg, poorer performances in attention and processing speed tasks were associated with a generalized amygdala enlargement, particularly of the basolateral and central complexes. The present findings extend our knowledge of amygdala involvement in cognition and suggest structural amygdala abnormalities as useful disease biomarkers in TLE.

Automatic Segmentation of Teeth, Crown-Bridge Restorations, Dental Implants, Restorative Fillings, Dental Caries, Residual Roots, and Root Canal Fillings on Orthopantomographs: Convenience and Pitfalls

BACKGROUND

The aim of our study is to provide successful automatic segmentation of various objects on orthopantomographs (OPGs).

METHODS

8138 OPGs obtained from the archives of the Department of Dentomaxillofacial Radiology were included. OPGs were converted into PNGs and transferred to the segmentation tool's database. All teeth, crown-bridge restorations, dental implants, composite-amalgam fillings, dental caries, residual roots, and root canal fillings were manually segmented by two experts with the manual drawing semantic segmentation technique.

RESULTS

The intra-class correlation coefficient (ICC) for both inter- and intra-observers for manual segmentation was excellent (ICC > 0.75). The intra-observer ICC was found to be 0.994, while the inter-observer reliability was 0.989. No significant difference was detected amongst observers (p = 0.947). The calculated DSC and accuracy values across all OPGs were 0.85 and 0.95 for the tooth segmentation, 0.88 and 0.99 for dental caries, 0.87 and 0.99 for dental restorations, 0.93 and 0.99 for crown-bridge restorations, 0.94 and 0.99 for dental implants, 0.78 and 0.99 for root canal fillings, and 0.78 and 0.99 for residual roots, respectively.

CONCLUSIONS

Thanks to faster and automated diagnoses on 2D as well as 3D dental images, dentists will have higher diagnosis rates in a shorter time even without excluding cases.

Human cortical amygdala dendrites and spines morphology under open‐source three‐dimensional reconstruction procedures

Visualizing nerve cells has been fundamental for the systematic description of brain structure and function in humans and other species. Different approaches aimed to unravel the morphological features of neuron types and diversity. The inherent complexity of the human nervous tissue and the need for proper histological processing have made studying human dendrites and spines challenging in postmortem samples. In this study, we used Golgi data and open-source software for 3D image reconstruction of human neurons from the cortical amygdaloid nucleus to show different dendrites and pleomorphic spines at different angles. Procedures required minimal equipment and generated high-quality images for differently shaped cells. We used the "single-section" Golgi method adapted for the human brain to engender 3D reconstructed images of the neuronal cell body and the dendritic ramification by adopting a neuronal tracing procedure. In addition, we elaborated 3D reconstructions to visualize heterogeneous dendritic spines using a supervised machine learning-based algorithm for image segmentation. These tools provided an additional upgrade and enhanced visual display of information related to the spatial orientation of dendritic branches and for dendritic spines of varied sizes and shapes in these human subcortical neurons. This same approach can be adapted for other techniques, areas of the central or peripheral nervous system, and comparative analysis between species.

Anxiety in children and youth with autism spectrum disorder and the association with amygdala subnuclei structure

Autism spectrum disorder (ASD) is clinically characterized by social and communication difficulties as well as repetitive behaviors. Many children with ASD also suffer from anxiety, which has been associated with alterations in amygdala structure. In this work, the association between amygdala subnuclei volumes and anxiety was assessed in a cohort of 234 participants (mean age = 11.0 years, SD = 3.9, 95 children with ASD, 139 children were non-autistic). Children underwent magnetic resonance imaging. Amygdala subnuclei volumes were extracted automatically. Anxiety was assessed using the Screen for Child Anxiety Related Disorders, the Child Behavior Checklist, and the Strength and Difficulties Questionnaire. Children with ASD had higher anxiety scores relative to non-autistic children on all anxiety measures (all, p < 0.05). Anxiety levels were significantly predicted in children with ASD by right basal (right: B = 0.235, p = 0.002) and paralaminar (PL) (B = −0.99, p = 0.009) volumes. Basal nuclei receive multisensory information from cortical and subcortical areas and have extensive projections within the limbic system while the PL nuclei are involved in emotional processing. Alterations in basal and PL nuclei in children with ASD and the association with anxiety may reflect morphological changes related to in the neurocircuitry of anxiety in ASD.

Lay abstract

Autism spectrum disorder (ASD) is clinically characterized by social communication difficulties as well as restricted and repetitive patterns of behavior. In addition, children with ASD are more likely to experience anxiety compared with their peers who do not have ASD. Recent studies suggest that atypical amygdala structure, a brain region involved in emotions, may be related to anxiety in children with ASD. However, the amygdala is a complex structure composed of heterogeneous subnuclei, and few studies to date have focused on how amygdala subnuclei relate to in anxiety in this population. The current sample consisted of 95 children with ASD and 139 non-autistic children, who underwent magnetic resonance imaging (MRI) and assessments for anxiety. The amygdala volumes were automatically segmented. Results indicated that children with ASD had elevated anxiety scores relative to peers without ASD. Larger basal volumes predicted greater anxiety in children with ASD, and this association was not seen in non-autistic children. Findings converge with previous literature suggesting ASD children suffer from higher levels of anxiety than non-autistic children, which may have important implications in treatment and interventions. Our results suggest that volumetric estimation of amygdala’s subregions in MRI may reveal specific anxiety-related associations in children with ASD.

Examining Associations Between Amygdala Volumes and Anxiety Symptoms in Autism Spectrum Disorder

BACKGROUND

Anxiety is one of the most common co-occurring conditions in people with autism spectrum disorder. The amygdala has been identified as being associated with anxiety in populations with and without autism, yet associations in autism were based on relatively small or developmentally constrained samples, leaving questions as to whether these results hold at different developmental ages and in a larger, more robust sample.

METHODS

Structural neuroimaging and parent report of anxiety symptoms of children ages 5-13 years with (n = 123) and without (n = 171) a diagnosis of autism were collected from the University of Maryland and three sites from the Autism Brain Imaging Data Exchange. Standardized residuals for bilateral amygdala volumes were computed adjusting for site, hemispheric volumes, and covariates (age, sex, Full Scale IQ).

RESULTS

Clinically significant anxiety symptoms did not differentiate amygdala volumes between groups (i.e., autism and anxiety, autism without anxiety, without autism or anxiety). No significant association between left or right amygdala volumes and anxiety scores was observed among the sample of individuals with autism. Meta-analytic and Bayes factor estimations provided additional support for the null hypothesis. Age, sex, and autism severity did not moderate associations between anxiety and amygdala volumes.

CONCLUSIONS

No relation between amygdala volumes and anxiety symptoms in children with autism was observed in the largest sample to investigate this question. We discuss directions for future research to determine whether additional factors including age or method of assessment may contribute to this lack of association.

The Changes of Amygdala Transcriptome in Autism Rat Model After Arginine Vasopressin Treatment

Background

Some studies have shown that arginine vasopressin (AVP) can significantly improve the social interaction disorder of autism, but the mechanism remains unclear.

Methods

Female Wistar rats were intraperitoneally injected with VPA or normal saline at embryonic day 12.5 to establish an autism model or normal control in their offspring. Male offspring prenatally exposed to VPA were randomly assigned to two groups: the VPA-induced autism model group and the AVP group. The rats in the AVP group were treated with intranasal AVP at postnatal day (PND) 21 and for 3 weeks. The VPA-induced autism model group was given the same dose of normal saline in the same way. Behavioral responses were evaluated in the open field and three-chambered social test apparatus; the expression levels of AVP in serum were detected by enzyme-linked immunosorbent assay kit, and the gene expression levels on the amygdala were measured by RNA-seq at PND42.

Results

Intranasal administration of AVP can significantly improve the social interaction disorder and elevate the levels of AVP in serum. Transcriptome sequencing results showed that 518 differently expressed genes (DEGs) were identified in the VPA-induced autism model group compared with the control in this study. Gene Ontology biological process enrichment analysis of DEGs showed that the VPA-induced autism model group had significant nervous system developmental impairments compared with the normal group, particularly in gliogenesis, glial cell differentiation, and oligodendrocyte differentiation. Gene Set Enrichment Analysis (GSEA) enrichment analysis also showed that biological process of oligodendrocyte differentiation, axoneme assembly, and axon ensheathment were inhibited in the VPA-induced autism model group. Pathway enrichment analysis of DEGs between the control and VPA-induced autism model group showed that the PI3K/AKT and Wnt pathways were significantly dysregulated in the VPA-induced autism model group. Few DEGs were found when compared with the transcriptome between the VPA-induced autism model group and the AVP treatment group. GSEA enrichment analysis showed deficits in oligodendrocyte development and function were significantly improved after AVP treatment; the pathways were mainly enriched in the NOTCH, mitogen-activated protein kinase, and focal adhesion signaling pathways, but not in the PI3K/AKT and Wnt pathways. The expression patterns analysis also showed the same results.

Conclusion

AVP can significantly improve the social interaction disorder of VPA-induced autism model, and AVP may target behavioral symptoms in autism by modulating the vasopressin pathways, rather than primary disease mechanisms.