Altered Cortical Thickness and Tract Integrity of the Mirror Neuron System and Associated Social Communication in Autism Spectrum Disorder

Neuropsychological profile of children with Autism Spectrum Disorder and children with Developmental Language Disorder and its relationship with social communication

OBJECTIVE

The objective of this study was to probe neuropsychological mechanisms of social communication in children with Autism Spectrum Disorders (ASD) and children with Developmental Language Disorders (DLD). Due to overlap of symptoms that include social dysfunction, diagnostic boundaries between these two developmental disorders remain unclear. This study hypothesizes that these two groups of children differ in the characteristics and in the underlying mechanisms of their social issues.

METHOD

This study examines a wide range of neuropsychological domains in search of a relationship with social communication. A total of 75 children with ASD and 26 children with DLD are included. A cross-battery assessment of neuropsychological functions is conducted, and social communication is evaluated using the Social Responsiveness Scale (SRS).

RESULTS

The neuropsychological profile for the ASD group differs from the DLD group, with the former demonstrating higher scores on Visual Processing and Comprehension, whereas the DLD group scores higher on Fluid Reasoning, Visual Processing and Processing Speed. Correlation analysis reveals that the association between neuropsychological domains and social communication differs between the groups.

DISCUSSION

Children with ASD and DLD clearly have distinctive neuropsychological profiles-their strengths and weaknesses are not equivalent. Such results motivate broad assessment of neuropsychological functions, as this assists in differentiating ASD from DLD for theragnostic purposes.

Microstructural abnormalities of the right hemisphere in preschool autism spectrum disorders

BACKGROUND

This study aims to investigate microstructural abnormalities within and between hemispheres in preschool children with autism spectrum disorders (ASD) using diffusion basis spectrum imaging (DBSI).

METHODS

A total of 35 ASD patients and 32 healthy controls (HC), matched for sex and age, underwent DBSI at 3T. We analyzed DBSI-derived indices of brain white matter using tract-based spatial statistics (TBSS) to compare ASD and HC groups. Support vector machine (SVM) classification was employed to evaluate the potential of positive DBSI parameters in distinguishing ASD patients. Additionally, correlation analyses were conducted to explore relationships between positive DBSI parameters and clinical scales.

RESULTS

Patients in the ASD group exhibited significantly higher fiber ratios in the right brainstem tracts, increased radial diffusivity in the left superior longitudinal fasciculus, and reduced fractional anisotropy (FA) in various fiber tracts, including projection, commissural, and association fibers, compared to HC. Notably, the FA of the right cingulum correlated positively with the Gesell scale (r = 0.439, p = 0.008) and achieved a specificity of 90% in identifying ASD.

CONCLUSION

The DBSI findings suggest asynchronous myelination in the right hemisphere and cerebellum in preschool ASD, with the FA value of the right cingulate gyrus appearing to be a reliable marker for ASD and may serve as a potential diagnostic parameter for preschool ASD.

Continuing to look in the mirror: A review of neuroscientific evidence for the broken mirror hypothesis, EP-M model and STORM model of autism spectrum conditions

The mirror neuron system has been argued to be a key brain system responsible for action understanding and imitation. Subsequently, mirror neuron system dysfunction has therefore been proposed to explain the social deficits manifested within autism spectrum condition, an approach referred to as the broken mirror hypothesis. Despite excitement surrounding this hypothesis, extensive research has produced insufficient evidence to support the broken mirror hypothesis in its pure form, and instead two alternative models have been formulated: EP-M model and the social top-down response modulation (STORM) model. All models suggest some dysfunction regarding the mirror neuron system in autism spectrum condition, be that within the mirror neuron system itself or systems that regulate the mirror neuron system. This literature review compares these three models in regard to recent neuroscientific investigations. This review concludes that there is insufficient support for the broken mirror hypothesis, but converging evidence supports an integrated EP-M and STORM model.

Reframing schizophrenia and autism as bodily self-consciousness disorders leading to a deficit of theory of mind and empathy with social communication impairments

Prior observations and studies suggest self-consciousness disorders in schizophrenia and Autism Spectrum Disorder (ASD), two neurodevelopmental disorders sharing social communication impairments. First, the relationships between schizophrenia and autism are explored regarding social communication impairments. Then, self-consciousness disorders in schizophrenia and autism are described and discussed in relation with impairments of body self leading to impairments of self-other differentiation, a deficit of theory of mind and empathy, and their consequences on social communication. Also, neurological dysfunction involved possibly in self-consciousness disorders in schizophrenia and autism is presented. In conclusion, a new model is proposed integrating results of studies presented here and stating the existence of bodily self-consciousness disorders in schizophrenia and autism associated with altered/absent intermodal sensory integration (especially visual-kinesthetic-tactile integration). This would result in problems of self-other differentiation, leading in turn to a deficit of theory of mind and empathy as well as social communication impairments. This model opens new perspectives to understand better self-consciousness disorders and social communication impairments in schizophrenia and ASD and to develop therapeutic strategies.

A Review of Functional and Structural Neurobiology of the Action Observation Network in Autism Spectrum Disorder and Developmental Coordination Disorder

Recent research has reported motor impairment similarities between children with developmental coordination disorder (DCD) and a subgroup of individuals with autism spectrum disorder (ASD). However, there is a debate as to whether DCD is a co-occurring diagnosis in individuals with ASD and motor impairments (ASDd), or if motor impairments in ASD are distinct from DCD. However, the etiology of motor impairments is not well understood in either disorder. Clarifying comorbidities in ASD is important to determine different etiopathological phenotyping clusters in ASD and to understand the variety of genetic and environmental factors that contribute to the disorder. Furthermore, this distinction has important therapeutic relevance. Here we explore the current neuroimaging findings in ASD and DCD and discusses possible neural mechanisms that underlie similarities and differences between the disorders.

Hyper memory, synaesthesia, savants Luria and Borges revisited

In this paper, we investigated two subjects with superior memory, or hyper memory: Solomon Shereshevsky, who was followed clinically for years by A. R. Luria, and Funes the Memorious, a fictional character created by J. L. Borges. The subjects possessed hyper memory, synaesthesia and symptoms of what we now call autistic spectrum disorder (ASD). We will discuss interactions of these characteristics and their possible role in hyper memory. Our study suggests that the hyper memory in our synaesthetes may have been due to their ASD-savant syndrome characteristics. However, this talent was markedly diminished by their severe deficit in categorization, abstraction and metaphorical functions. As investigated by previous studies, we suggest that there is altered connectivity between the medial temporal lobe and its connections to the prefrontal cingulate and amygdala, either due to lack of specific neurons or to a more general neuronal dysfunction.

Social communication disorder: a narrative review on current insights

Social communication disorder (SCD) is a novel diagnosis listed under the rubric of communication disorders within the Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5) and it is reported to be characterized by impairment in use of verbal and nonverbal communication for social aims. This review attempts to summarize the current understanding of the SCD concept along with its evolution and presents data from previous studies conducted. Suggestions for further research are also delineated. As listed in DSM-5, the criteria for this novel diagnosis are vague, display elevated comorbidity with other neurodevelopmental disorders and other childhood psychopathologies, and show partial overlap with autistic spectrum disorders both in terms of genetics and family histories. Data on cross-cultural presentations and temporal stability are also limited. The social communication model proposed by Catani and Bambini may help integrate the neurobiological findings pertaining to SCD. Valid and reliable assessment methods need to be developed for SCD. This may involve either development of novel instruments capturing the DSM-5 criteria or application of statistical methods such as item response theory to existing instruments. The relationships between broad autism phenotype, pragmatic language impairment, nonverbal learning disorder, learning disorders, autistic spectrum disorders, and SCD should be evaluated with further studies.

White Matter Microstructure of the Human Mirror Neuron System is Related to Symptom Severity in Adults with Autism

Mirror neuron system (MNS) dysfunctions might underlie deficits in autism spectrum disorders (ASD). Diffusion tensor imaging based probabilistic tractography was conducted in 15 adult ASD patients and 13 matched, healthy controls. Fractional anisotropy (FA) was quantified to assess group differences in tract-related white matter microstructure of both the classical MNS route (mediating "emulation") and the alternative temporo-frontal route (mediating "mimicry"). Multiple linear regression was used to investigate structure-function relationships between MNS connections and ASD symptom severity. There were no significant group differences in tract-related FA indicating an intact classical MNS in ASD. Direct temporo-frontal connections could not be reconstructed challengeing the concept of multiple routes for imitation. Tract-related FA of right-hemispheric parieto-frontal connections was negatively related to autism symptom severity.