The Directionality of Fronto-Posterior Brain Connectivity Is Associated with the Degree of Individual Autistic Traits

Abstract

Altered patterns of brain connectivity have been found in autism spectrum disorder (ASD) and associated with specific symptoms and behavioral features. Growing evidence suggests that the autistic peculiarities are not confined to the clinical population but extend along a continuum between healthy and maladaptive conditions. The aim of this study was to investigate whether a differentiated connectivity pattern could also be tracked along the continuum of autistic traits in a non-clinical population. A Granger causality analysis conducted on a resting-state EEG recording showed that connectivity along the posterior-frontal gradient is sensitive to the magnitude of individual autistic traits and mostly conveyed through fast oscillatory activity. Specifically, participants with higher autistic traits were characterized by a prevalence of ascending connections starting from posterior regions ramping the cortical hierarchy. These findings point to the presence of a tendency within the neural mapping of individuals with higher autistic features in conveying proportionally more bottom-up information. This pattern of findings mimics those found in clinical forms of autism, supporting the idea of a neurobiological continuum between autistic traits and ASD.

Bottom-up vs. top-down connectivity imbalance in individuals with high-autistic traits: An electroencephalographic study

“…For this study, we focused on centrality indices that take into account the direction of connections, specifically authority, hubness, in degree, and out degree centralities. These indices, which will be detailed in the following, were specifically selected for their focus on the ROIs' inputs and outputs, which we hypothesized could offer confirmatory evidence of connectivity patterns previously observed in individuals with low and high autistic traits (Tarasi et al, 2021).…”

“…Following these ideas, in a recent paper (Tarasi et al, 2021), we investigated whether the patterns of brain connectivity, estimated with Granger causality from EEG source reconstruction, exhibit differences in two nonclinical groups classified as low or high on autistic traits. Preliminary results suggested that connectivity along the fronto-posterior axis is sensitive to the magnitude of the autistic features and that a prevalence of ascending connections characterized participants with higher autistic traits.…”

Neural Networks and Connectivity among Brain Regions

“…On the other hand, the use of EEG data is receiving increasing attention in the current literature due to the simplicity of the experimental setup and its capacity to detect rapid temporal changes in neural activity. Three papers in this Special Issue infer connectivity from EEG ( [8][9][10]). The first two papers use Granger connectivity (bivariate in Tarasi et al [9] and multivariate in Formaggio et al [8]).…”

“…Three papers in this Special Issue infer connectivity from EEG ( [8][9][10]). The first two papers use Granger connectivity (bivariate in Tarasi et al [9] and multivariate in Formaggio et al [8]). In contrast, the last paper (Taberna et al [10]) uses a different approach based on band-limited power envelope correlations.…”

“…The method employs three stages, in which neural networks are trained on the correlation-based connectivity matrix, and finally a subset of features is extracted, which is able to discriminate between the autistic patients and healthy controls. Conversely, the paper by Tarasi et al [9] uses both temporal and spectral Granger connectivity networks, based on source electrical activity reconstructed from resting-state EEG data, to infer differences in connectivity between two classes of non-clinical subjects with lower or higher autistic traits. The fundamental result is that the brain network in individuals with higher autistic traits is more based on bottom-up information.…”