Connectivity in Autism

Abstract

Autism Spectrum Disorder (ASD) affects 1 in 50 children between the ages of 6–17 years as per a 2012 CDC survey of parents. The etiology of ASD is not precisely known. ASD is an umbrella term, which includes low (IQ<70) to high functioning (IQ>70) individuals. A better understanding of the disorder, and how it manifests in an individual subject can lead to more effective intervention plans to fulfill the individual’s treatment needs. Magnetic resonance imaging (MRI) is a non-invasive investigational tool that can help study the ways in which the brain develops and/or deviates from the typical developmental trajectory. MRI offers insights into the structure, function, and metabolism of the brain. In this article, we review published studies on brain connectivity changes in ASD using either resting state functional MRI or diffusion tensor imaging. The general findings of decreases in white matter integrity and long-range neural coherence are prevalent in ASD literature. However, there is somewhat less of a consensus in the detailed localization of these findings. There are even fewer studies linking these connectivity alterations with the behavioral phenotype of the disorder. Nevertheless, with the help of data sharing and large-scale analytic efforts, the field is advancing towards several convergent themes. These include reduced functional coherence of long-range intra-hemispheric cortico-cortical default mode circuitry, impaired inter-hemispheric regulation, and an associated, perhaps compensatory, increase in local and short-range cortico-subcortical coherence.

Wavelet coherence-based classifier: A resting-state functional MRI study on neurodynamics in adolescents with high-functioning autism

“…For further analysis, we focused on the seven fronto-parietal and temporal networks, typically involved in the executive and socio-cognitive functions, since they are proven to be relevant large-scale functional networks impaired in ASD [2,3,5,9] The seven networks, depicted in Fig. 1 , encompass the ventral stream (VENT) network, the central-executive network (EXE), the fronto-parietal left and right (respectively FPL, FPR), the auditory system (AUDI), the visual cortex (VISU) and the default-mode network (DMN).…”

“…Over the past decade, ASD has been studied using fMRI, in setups where participants had to perform a specific task or during resting-state fMRI, in order to find a biomarker for autism. Unfortunately, current literature provides mixed and inconsistent results regarding strength and location of functional disparities [2][3][4][5] . Yet, several attempts to classify autism, based on functional connectivity measurements have been made [6,7] .…”

Electrophysiological signatures of atypical intrinsic brain connectivity networks in autism

“…Disrupted functional connectivity has been reported in autism spectrum disorder (ASD) (Vissers et al, 2012; Wass, 2011) in functional magnetic resonance imaging (fMRI) (Muller et al, 2011; Rane et al, 2015), electroencephalography (EEG) (Boutros et al, 2015; Wang et al, 2013), and magnetoencephalography (MEG) data (Lajiness-O’ Neill et al, 2014). However, the nature of these disruptions, e.g., increased or decreased connectivity and their specificity in functional domains, remains elusive.…”

Facilitating Neurofeedback in Children with Autism and Intellectual Impairments Using TAGteach

“…Converging findings from brain imaging research have given rise to theories on the neuroetiology of ASD. Studies on functional communication across brain networks have been reporting patterns of hypo-coherence in long-range default mode networks, inter-and intra-hemispheric hypo-connectivity, and hyperconnectivity in local and long-distance networks (Kahn et al 2015;Mohammad-Rezazadeh et al 2016;Müller et al 2011;Rane et al 2015), although the methodologies applied and results reported have been inconsistent. Moreover, the manner in which dysfunctional connectivity specifically impacts core ASD symptoms or the degree of severity has not been clearly delineated thus far.…”