Research On The Functional And Structural Gradients Of The Insula In Autism Spectrum Disorder

The functional organization of the brain can be represented as a low-dimensional space reflecting its macroscopic hierarchy.The dimension of this space is described as a connection gradient,capturing the similarity of regional connections along a continuous space.The insula is a complex and heterogeneous structure located in the lateral sulci of the cerebral hemisphere.The insula plays a crucial role in large neural networks due to its multiple structural connections.At present,the macroscopic functional and structural hierarchy of the human insular cortex are still unclear.But the abnormalities of the insu-lar structure and function have been reported in a diversity of neuropsychiatric disorders,of which Autism spectrum disorder（ASD）is a pervasive neurodevelopmental disorder characterized by repetitive stereotyped behaviors,social communication disorders,and speech communication disorders.Pioneering studies of neuroimaging have shown signif-icant abnormalities in the function and structure of the insula in autism.However,while the functional and structural gradient patterns of the insula in in autism are still unclear.The following studies were conducted around the functional and structural gradients of the insula in healthy subjects and autism:This thesis assessed the functional and structural gradients of the insular cortex in a dataset of healthy subjects using a novel diffusion embedding analysis method to delineate insular functional and insular structural gradients.This thesis identified two principle axes of functional connectivity and structural covariant patterns and examined relationships with insula intrinsic geometry and specific cognitive functions.This thesis found that the insular functional principle gradient is an anterior/posterior axis and captures associa-tions with insula microstructure and is strongly correlated with spatial distance,indicating the importance of intrinsic geometry in functional hierarchies,providing insight into be-havioural representation of a systemic shift in cognitive function.The second gradient is a dorsal/ventral axis.There is a corresponding similarity between functional and structual gradients,reflecting the coordination of insula structural and functional interactions.This study delineates the distribution pattern of functional and structural gradients in the insula,and the macroscopic gradient shows the coordination of the interaction of structure and function.The biological relevance is supported by investigating how pathologies known to act on functional connectivity affect connectivity gradients.Recent studies have used gradient analysis to explore the abnormal brain macroscopic functions in autism,but the previ-ous studies on insula abnormalities in autism still focused on changes in connectivity and structure.In follow-up studies,we will focus on abnormalities in the insular functional and structural gradients patterns in autism.This thesis obtained the insular functional gradients and cortical thickness-based insular structural gradient in autism using gradient analysis.This thesis found that autisms and the healthy subjects had similar insular functional gra-dient directions,but there were regions of significant differences in gradient scores.This thesis found the relationship between the social response symptoms of autism and abnor-mal insular functional gradients’ parttens.This thesis also found that the distribution of the left insular structural principle gradient and the secondary gradient in autism and healthy subjects are significantly different.This thesis found abnormalities in the functional gra-dient and structural gradient pattern of the insula in autism.These results proposed a new framework to describe the connection changes of the insula in autism,which pointed out a feasible follow-up research direction for the study of the insular gradients in autism.