ORCID Profile
0000-0002-4894-4823
Current Organisations
University College Cork and HSE Healthcare Leadership Academy
,
Trinity College Dublin
,
HSE
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Publisher: Wiley
Date: 04-08-2012
DOI: 10.1002/AUR.1245
Abstract: Atypical visuospatial processing is commonly described in autism spectrum disorders (ASDs) however the specific neurobiological underpinnings of this phenomenon are poorly understood. Given the extensive evidence suggesting ASDs are characterized by abnormal neural connectivity, this study aimed to investigate network connectivity during visuospatial processing in ASD. Twenty-two males with ASD without intellectual disability and 22 in idually matched controls performed a mental rotation task during functional magnetic resonance imaging (MRI) in which two rotated stimuli were judged to be same ("Same Trials") or mirror-imaged ("Mirror Trials"). Behavioral results revealed a relative advantage of mental rotation in the ASD group-controls were slower responding to the more difficult Mirror Trials than Same Trials whereas the ASD group completed Mirror Trials and Same-trials at similar speeds. In the ASD group, brain activity was reduced in frontal, temporal, occipital, striatal, and cerebellar regions and, consistent with previous literature, functional connectivity between a number of brain regions was reduced. However, some connections appeared to be conserved and were recruited in a qualitatively different way by the two groups. As task difficulty increased (on Mirror Trials), controls tended to increase connections between certain brain regions, whereas the ASD group appeared to suppress connections between these regions. There was an interesting exception to this pattern in the visual cortex, a finding that may suggest an advantage in early visual perceptual processing in ASD. Overall, this study has identified a relative advantage in mental rotation in ASD that is associated with aberrant neural connectivity and that may stem from enhanced visual perceptual processing.
Publisher: Cold Spring Harbor Laboratory
Date: 18-06-2019
DOI: 10.1101/673012
Abstract: Attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and obsessive-compulsive disorder (OCD) are common neurodevelopmental disorders that frequently co-occur. We aimed to directly compare all three disorders. The ENIGMA consortium is ideally positioned to investigate structural brain alterations across these disorders. Structural T1-weighted whole-brain MRI of controls ( n =5,827) and patients with ADHD (n=2,271), ASD (n=1,777), and OCD (n=2,323) from 151 cohorts worldwide were analyzed using standardized processing protocols. We examined subcortical volume, cortical thickness and surface area differences within a mega-analytical framework, pooling measures extracted from each cohort. Analyses were performed separately for children, adolescents, and adults using linear mixed-effects models adjusting for age, sex and site (and ICV for subcortical and surface area measures). We found no shared alterations among all three disorders, while shared alterations between any two disorders did not survive multiple comparisons correction. Children with ADHD compared to those with OCD had smaller hippoc al volumes, possibly influenced by IQ. Children and adolescents with ADHD also had smaller ICV than controls and those with OCD or ASD. Adults with ASD showed thicker frontal cortices compared to adult controls and other clinical groups. No OCD-specific alterations across different age-groups and surface area alterations among all disorders in childhood and adulthood were observed. Our findings suggest robust but subtle alterations across different age-groups among ADHD, ASD, and OCD. ADHD-specific ICV and hippoc al alterations in children and adolescents, and ASD-specific cortical thickness alterations in the frontal cortex in adults support previous work emphasizing neurodevelopmental alterations in these disorders.
Publisher: Wiley
Date: 18-05-2020
DOI: 10.1002/HBM.25029
Abstract: Neuroimaging has been extensively used to study brain structure and function in in iduals with attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) over the past decades. Two of the main shortcomings of the neuroimaging literature of these disorders are the small s le sizes employed and the heterogeneity of methods used. In 2013 and 2014, the ENIGMA‐ADHD and ENIGMA‐ASD working groups were respectively, founded with a common goal to address these limitations. Here, we provide a narrative review of the thus far completed and still ongoing projects of these working groups. Due to an implicitly hierarchical psychiatric diagnostic classification system, the fields of ADHD and ASD have developed largely in isolation, despite the considerable overlap in the occurrence of the disorders. The collaboration between the ENIGMA‐ADHD and ‐ASD working groups seeks to bring the neuroimaging efforts of the two disorders closer together. The outcomes of case–control studies of subcortical and cortical structures showed that subcortical volumes are similarly affected in ASD and ADHD, albeit with small effect sizes. Cortical analyses identified unique differences in each disorder, but also considerable overlap between the two, specifically in cortical thickness. Ongoing work is examining alternative research questions, such as brain laterality, prediction of case–control status, and anatomical heterogeneity. In brief, great strides have been made toward fulfilling the aims of the ENIGMA collaborations, while new ideas and follow‐up analyses continue that include more imaging modalities (diffusion MRI and resting‐state functional MRI), collaborations with other large databases, and s les with dual diagnoses.
Publisher: Wiley
Date: 18-03-2013
DOI: 10.1002/AUR.1290
Abstract: Autism spectrum disorders (ASDs) are associated with a marked disturbance of neural functional connectivity, which may arise from disrupted organization of white matter. The aim of this study was to use constrained spherical deconvolution (CSD)-based tractography to isolate and characterize major intrahemispheric white matter tracts that are important in visuospatial processing. CSD-based tractography avoids a number of critical confounds that are associated with diffusion tensor tractography, and to our knowledge, this is the first time that this advanced diffusion tractography method has been used in autism research. Twenty-five participants with ASD and aged 25, intelligence quotient-matched controls completed a high angular resolution diffusion imaging scan. The inferior fronto-occipital fasciculus (IFOF) and arcuate fasciculus were isolated using CSD-based tractography. Quantitative diffusion measures of white matter microstructural organization were compared between groups and associated with visuospatial processing performance. Significant alteration of white matter organization was present in the right IFOF in in iduals with ASD. In addition, poorer visuospatial processing was associated in in iduals with ASD with disrupted white matter in the right IFOF. Using a novel, advanced tractography method to isolate major intrahemispheric white matter tracts in autism, this research has demonstrated that there are significant alterations in the microstructural organization of white matter in the right IFOF in ASD. This alteration was associated with poorer visuospatial processing performance in the ASD group. This study provides an insight into structural brain abnormalities that may influence atypical visuospatial processing in autism.
Publisher: Springer Science and Business Media LLC
Date: 08-02-2022
DOI: 10.1038/S41380-022-01452-7
Abstract: Small average differences in the left-right asymmetry of cerebral cortical thickness have been reported in in iduals with autism spectrum disorder (ASD) compared to typically developing controls, affecting widespread cortical regions. The possible impacts of these regional alterations in terms of structural network effects have not previously been characterized. Inter-regional morphological covariance analysis can capture network connectivity between different cortical areas at the macroscale level. Here, we used cortical thickness data from 1455 in iduals with ASD and 1560 controls, across 43 independent datasets of the ENIGMA consortium’s ASD Working Group, to assess hemispheric asymmetries of intra-in idual structural covariance networks, using graph theory-based topological metrics. Compared with typical features of small-world architecture in controls, the ASD s le showed significantly altered average asymmetry of networks involving the fusiform, rostral middle frontal, and medial orbitofrontal cortex, involving higher randomization of the corresponding right-hemispheric networks in ASD. A network involving the superior frontal cortex showed decreased right-hemisphere randomization. Based on comparisons with meta-analyzed functional neuroimaging data, the altered connectivity asymmetry particularly affected networks that subserve executive functions, language-related and sensorimotor processes. These findings provide a network-level characterization of altered left-right brain asymmetry in ASD, based on a large combined s le. Altered asymmetrical brain development in ASD may be partly propagated among spatially distant regions through structural connectivity.
Publisher: Frontiers Media SA
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 14-10-2011
Publisher: American Psychiatric Association Publishing
Date: 09-2020
Publisher: Springer Science and Business Media LLC
Date: 31-10-2019
DOI: 10.1038/S41467-019-13005-8
Abstract: Altered structural brain asymmetry in autism spectrum disorder (ASD) has been reported. However, findings have been inconsistent, likely due to limited s le sizes. Here we investigated 1,774 in iduals with ASD and 1,809 controls, from 54 independent data sets of the ENIGMA consortium. ASD was significantly associated with alterations of cortical thickness asymmetry in mostly medial frontal, orbitofrontal, cingulate and inferior temporal areas, and also with asymmetry of orbitofrontal surface area. These differences generally involved reduced asymmetry in in iduals with ASD compared to controls. Furthermore, putamen volume asymmetry was significantly increased in ASD. The largest case-control effect size was Cohen’s d = −0.13, for asymmetry of superior frontal cortical thickness. Most effects did not depend on age, sex, IQ, severity or medication use. Altered lateralized neurodevelopment may therefore be a feature of ASD, affecting widespread brain regions with erse functions. Large-scale analysis was necessary to quantify subtle alterations of brain structural asymmetry in ASD.
Publisher: Wiley
Date: 26-11-2014
DOI: 10.1002/AUR.1430
Abstract: Attention orienting is a cognitive process that facilitates the movement of attention focus from one location to another: this may be impaired in autism spectrum disorder (ASD). Dorsal and ventral attention networks (DAN and VAN) sub-serve the process of attention orienting. This study investigated the functional connectivity of attention orienting in these networks in ASD using the Posner Cueing Task. Twenty-one adolescents with ASD and 21 age and IQ matched controls underwent functional magnetic resonance imaging. A psychophysical interaction (PPI) analysis was implemented to investigate task-dependent functional connectivity, measuring synchronicity of brain regions during the task. Regions of interest (ROI) were selected to explore functional connectivity in the DAN during cue-only conditions and in the VAN during invalid and valid trials. Behaviourally, the ASD and control groups performed the task in a similar manner. Functional MRI results indicated that the ASD and control groups activated similar brain regions. During invalid trials (VAN), the ASD group showed significant positive functional connectivity to multiple brain regions, whilst the control group demonstrated negative connectivity. During valid trials (VAN), the two groups also showed contrasting patterns of connectivity. In the cue-only conditions (DAN), the ASD group showed weaker functional connectivity. The DAN analysis suggests that the ASD group has weaker coherence between brain areas involved in goal-driven, endogenous attention control. The strong positive functional connectivity exhibited by the ASD group in the VAN during the invalid trials suggests that in iduals with ASD may generate compensatory mechanisms to achieve neurotypical behaviour. These results support the theory of abnormal cortical connectivity in autism.
Location: Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jane McGrath.