International Review of Neurobiology : Neurobiology of Autism
L’International Review of Neurobiology consacre son dernier numéro de 2013 à la neurobiologie de l’autisme.
1. Becker EBE, Stoodley CJ. Chapter One – Autism Spectrum Disorder and the Cerebellum. International Review of Neurobiology ;2013 ;Volume 113:1-34.
The cerebellum has been long known for its importance in motor learning and coordination. Recently, anatomical, clinical, and neuroimaging studies strongly suggest that the cerebellum supports cognitive functions, including language and executive functions, as well as affective regulation. Furthermore, the cerebellum has emerged as one of the key brain regions affected in autism. Here, we discuss our current understanding of the role of the cerebellum in autism, including evidence from genetic, molecular, clinical, behavioral, and neuroimaging studies. Cerebellar findings in autism suggest developmental differences at multiple levels of neural structure and function, indicating that the cerebellum is an important player in the complex neural underpinnings of autism spectrum disorder, with behavioral implications beyond the motor domain.
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2. Wilkinson B, Campbell DB. Chapter Two – Contribution of Long Noncoding RNAs to Autism Spectrum Disorder Risk. International Review of Neurobiology ;2013 ;Volume 113:35-59.
Accumulating evidence indicates that long noncoding RNAs (lncRNAs) contribute to autism spectrum disorder (ASD) risk. Although a few lncRNAs have long been recognized to have important functions, the vast majority of this class of molecules remains uncharacterized. Because lncRNAs are more abundant in human brain than protein-coding RNAs, it is likely that they contribute to brain disorders, including ASD. We review here the known functions of lncRNAs and the potential contributions of lncRNAs to ASD.
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3. Maloney SE, Rieger MA, Dougherty JD. Chapter Three – Identifying Essential Cell Types and Circuits in Autism Spectrum Disorders. International Review of Neurobiology ;2013 ;Volume 113:61-96.
Autism spectrum disorder (ASD) is highly genetic in its etiology, with potentially hundreds of genes contributing to risk. Despite this heterogeneity, these disparate genetic lesions may result in the disruption of a limited number of key cell types or circuits—information which could be leveraged for the design of therapeutic interventions. While hypotheses for cellular disruptions can be identified by postmortem anatomical analysis and expression studies of ASD risk genes, testing these hypotheses requires the use of animal models. In this review, we explore the existing evidence supporting the contribution of different cell types to ASD, specifically focusing on rodent studies disrupting serotonergic, GABAergic, cerebellar, and striatal cell types, with particular attention to studies of the sufficiency of specific cellular disruptions to generate ASD-related behavioral abnormalities. This evidence suggests multiple cellular routes can create features of the disorder, though it is currently unclear if these cell types converge on a final common circuit. We hope that in the future, systematic studies of cellular sufficiency and genetic interaction will help to classify patients into groups by type of cellular disruptions which suggest tractable therapeutic targets.
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4. Lepp S, Anderson A, Konopka G. Chapter Four – Connecting Signaling Pathways Underlying Communication to ASD Vulnerability. International Review of Neurobiology ;2013 ;Volume 113:97-133.
Language is a human-specific trait that likely facilitated the rapid increase in higher cognitive function in our species. A consequence of the selective pressures that have permitted language and cognition to flourish in humans is the unique vulnerability of humans to developing cognitive disorders such as autism. Therefore, progress in understanding the genetic and molecular mechanisms of language evolution should provide insight into such disorders. Here, we discuss the few genes that have been identified in both autism-related pathways and language. We also detail the use of animal models to uncover the function of these genes at a mechanistic and circuit level. Finally, we present the use of comparative genomics to identify novel genes and gene networks involved in autism. Together, all of these approaches will allow for a broader and deeper view of the molecular brain mechanisms involved in the evolution of language and the gene disruptions associated with autism.
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5. Peng Y, Huentelman M, Smith C, Qiu S. Chapter Five – MET Receptor Tyrosine Kinase as an Autism Genetic Risk Factor. International Review of Neurobiology ;2013 ;Volume 113:135-165.
In this chapter, we will briefly discuss recent literature on the role of MET receptor tyrosine kinase (RTK) in brain development and how perturbation of MET signaling may alter normal neurodevelopmental outcomes. Recent human genetic studies have established MET as a risk factor for autism, and the molecular and cellular underpinnings of this genetic risk are only beginning to emerge from obscurity. Unlike many autism risk genes that encode synaptic proteins, the spatial and temporal expression pattern of MET RTK indicates this signaling system is ideally situated to regulate neuronal growth, functional maturation, and establishment of functional brain circuits, particularly in those brain structures involved in higher levels of cognition, social skills, and executive functions.
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6. Kwan KY. Chapter Six – Transcriptional Dysregulation of Neocortical Circuit Assembly in ASD. International Review of Neurobiology ;2013 ;Volume 113:167-205.
Autism spectrum disorders (ASDs) impair social cognition and communication, key higher-order functions centered in the human neocortex. The assembly of neocortical circuitry is a precisely regulated developmental process susceptible to genetic alterations that can ultimately affect cognitive abilities. Because ASD is an early onset neurodevelopmental disorder that disrupts functions executed by the neocortex, miswiring of neocortical circuits has been hypothesized to be an underlying mechanism of ASD. This possibility is supported by emerging genetic findings and data from imaging studies. Recent research on neocortical development has identified transcription factors as key determinants of neocortical circuit assembly, mediating diverse processes including neuronal specification, migration, and wiring. Many of these TFs (TBR1, SOX5, FEZF2, and SATB2) have been implicated in ASD. Here, I will discuss the functional roles of these transcriptional programs in neocortical circuit development and their neurobiological implications for the emerging etiology of ASD.
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7. Chukoskie L, Townsend J, Westerfield M. Chapter Seven – Motor Skill in Autism Spectrum Disorders : A Subcortical View. International Review of Neurobiology ;2013 ;Volume 113:207-249.
The earliest observable symptoms of autism spectrum disorders (ASDs) involve motor behavior. There is a growing awareness of the developmental importance of impaired motor function in ASD and its association with social skill. Compromised motor function requires increased attention, leaving fewer resources available for processing environmental stimuli and learning. This knowledge suggests that the motor system—which we know to be trainable—may be a gateway to improving outcomes of individuals living with ASD. In this review, we suggest a framework borrowed from machine learning to examine where, why, and how motor skills are different in individuals with ASD.
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8. Bill BR, Lowe JK, DyBuncio CT, Fogel BL. Chapter Eight – Orchestration of Neurodevelopmental Programs by RBFOX1 : Implications for Autism Spectrum Disorder. International Review of Neurobiology ;2013 ;Volume 113:251-267.
Neurodevelopmental and neuropsychiatric disorders result from complex interactions between critical genetic factors and as-yet-unknown environmental components. To gain clinical insight, it is critical to develop a comprehensive understanding of these genetic components. RBFOX1, an RNA splicing factor, regulates expression of large genetic networks during early neuronal development, and haploinsufficiency causes severe neurodevelopmental phenotypes including autism spectrum disorder (ASD), intellectual disability, and epilepsy. Genomic testing in individuals and large patient cohorts has identified phenotypically similar cases possessing copy number variations in RBFOX1, implicating the gene as an important cause of neurodevelopmental disease. However, a significant proportion of the observed structural variation is inherited from phenotypically normal individuals, raising questions regarding overall pathogenicity of variation at the RBFOX1 locus. In this chapter, we discuss the molecular, cellular, and clinical evidence supporting the role of RBFOX1 in neurodevelopment and present a comprehensive model for the contribution of structural variation in RBFOX1 to ASD.
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9. Hsiao EY. Chapter Nine – Immune Dysregulation in Autism Spectrum Disorder. International Review of Neurobiology ;2013 ;Volume 113:269-302.
Autism spectrum disorder (ASD) is a highly heterogeneous disorder diagnosed based on the presence and severity of core abnormalities in social communication and repetitive behavior, yet several studies converge on immune dysregulation as a feature of ASD. Widespread alterations in immune molecules and responses are seen in the brains and periphery of ASD individuals, and early life immune disruptions are associated with ASD. This chapter discusses immune-related environmental and genetic risk factors for ASD, emphasizing population-wide studies and animal research that reveal potential mechanistic pathways involved in the development of ASD-related symptoms. It further reviews immunologic pathologies seen in ASD individuals and how such abnormalities can impact neurodevelopment and behavior. Finally, it evaluates emerging evidence for an immune contribution to the pathogenesis of ASD and a potential role for immunomodulatory effects in current treatments for ASD.
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10. Miyauchi S, Voineagu I. Chapter Ten – Autism Susceptibility Genes and the Transcriptional Landscape of the Human Brain. International Review of Neurobiology ;2013 ;Volume 113:303-318.
Autism is the most severe end of a spectrum of neurodevelopmental conditions, autism spectrum disorders (ASD). ASD are genetically heterogeneous, and hundreds of genes have been implicated in the etiology of the disease. Here, we discuss the contribution of brain transcriptome studies in advancing our understanding of the genetic mechanisms of ASD and review recent work characterizing the spatial and temporal variation of the human brain transcriptome, with a focus on the relevance of these data to autism susceptibility genes.
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11. Konopka G. Preface : The Neurobiology of Autism : Integrating Genetics, Brain Development, Behavior, and the Environment. International Review of Neurobiology ;2013 ;Volume 113:xi-xii.
