Links Between Thalamocortical and Cerebrocerebellar Functional Connectivity in Autism Spectrum Disorder PDF Download
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Category : Electronic books
Languages : en
Pages : 52
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Book Description
Autism spectrum disorder (ASD) is a set of developmental disorders characterized by impacted social and communicative abilities, restricted interests, and repetitive behaviors. Recent ASD research has shown that network-level communication within the brain may play a large role in the manifestation of these symptoms. Specifically, recent studies have suggested domain-specific patterns of increased connectivity for sensorimotor connections and decreased connectivity for supramodal or associative connections for both thalamocortical and cerebrocerebellar circuits in ASD. The current study aimed to test whether functional connectivity between cerebellar lobules and the neocortex was related to functional connectivity between thalamic nuclei and the neocortex. We further sought to determine how these deep brain functional connectivity patterns correlated with ASD symptom severity as measured by clinical assessments. Archival resting state fMRI data from 49 ASD and 49 typically developing (TD) participants (aged 7 to 17 years) were used for this study. ASD and TD participants were matched at the group level on age, nonverbal IQ, and in-scanner head motion. A standard fMRI preprocessing pipeline was utilized, including motion, slice-time, and field map correction, spatial smoothing and bandpass filtering, and removal of nuisance regressors (i.e., 6 rigid-body motion parameters, and signal from white matter and ventricles). Regions of interest (ROIs) for cerebral cortex, thalamic regions, and cerebellar lobules were obtained from the Jülich histological and Harvard-Oxford atlases. Total correlation analyses between the mean time series of each cortical ROI and deep brain parcel showed widespread overconnectivity in the ASD group compared to the TD group. This was the case for both thalamocortical and cerebrocerebellar iFC circuits, stemming from both sensorimotor and supramodal cortical seeds. These circuits also showed far less specificity in ASD, with generally higher correlations between the iFC pairings themselves. Finally, it was shown that for participants with ASD, as iFC patterns deviated from those of the TD group, symptom severity based on clinical assessments also worsened across several domains. These findings suggest that thalamocortical and cerebrocerebellar iFC may be guided by similar neural dynamics, which may have many implications for developmental hypotheses of ASD that focus on network formation.
Author:
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ISBN:
Category : Electronic books
Languages : en
Pages : 52
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Book Description
Autism spectrum disorder (ASD) is a set of developmental disorders characterized by impacted social and communicative abilities, restricted interests, and repetitive behaviors. Recent ASD research has shown that network-level communication within the brain may play a large role in the manifestation of these symptoms. Specifically, recent studies have suggested domain-specific patterns of increased connectivity for sensorimotor connections and decreased connectivity for supramodal or associative connections for both thalamocortical and cerebrocerebellar circuits in ASD. The current study aimed to test whether functional connectivity between cerebellar lobules and the neocortex was related to functional connectivity between thalamic nuclei and the neocortex. We further sought to determine how these deep brain functional connectivity patterns correlated with ASD symptom severity as measured by clinical assessments. Archival resting state fMRI data from 49 ASD and 49 typically developing (TD) participants (aged 7 to 17 years) were used for this study. ASD and TD participants were matched at the group level on age, nonverbal IQ, and in-scanner head motion. A standard fMRI preprocessing pipeline was utilized, including motion, slice-time, and field map correction, spatial smoothing and bandpass filtering, and removal of nuisance regressors (i.e., 6 rigid-body motion parameters, and signal from white matter and ventricles). Regions of interest (ROIs) for cerebral cortex, thalamic regions, and cerebellar lobules were obtained from the Jülich histological and Harvard-Oxford atlases. Total correlation analyses between the mean time series of each cortical ROI and deep brain parcel showed widespread overconnectivity in the ASD group compared to the TD group. This was the case for both thalamocortical and cerebrocerebellar iFC circuits, stemming from both sensorimotor and supramodal cortical seeds. These circuits also showed far less specificity in ASD, with generally higher correlations between the iFC pairings themselves. Finally, it was shown that for participants with ASD, as iFC patterns deviated from those of the TD group, symptom severity based on clinical assessments also worsened across several domains. These findings suggest that thalamocortical and cerebrocerebellar iFC may be guided by similar neural dynamics, which may have many implications for developmental hypotheses of ASD that focus on network formation.
Author: Aarti Nair
Publisher:
ISBN: 9781321928600
Category : Autism spectrum disorders in children
Languages : en
Pages : 74
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Rationale : The present dissertation project specifically sought to understand brain networks connecting with the thalamus, an important subcortical relay structure through which almost all sensory information is routed. In view of the known fundamental importance of thalamocortical connectivity for the development of regional functional specialization in cerebral cortex, it is surprising how little firm knowledge is available about the thalamus and its connections with cortex in Autism Spectrum Disorders (ASD). Therefore, it is crucial to examine the role of the thalamus in regulating these functions for an improved understanding of neurodevelopmental mechanisms associated with ASD. Design : The first study of this project examined functional and anatomical connectivity between five broad cortical regions of interests (ROIs; e.g., temporal lobes) and the thalamus for a sample of children and adolescents with ASD (N=26) compared to TD controls (N=27). This first study allowed us to broadly characterize the connectivity between ipsilateral thalamus and the different lobes. In the second study, we delved deeper into the specificity of connections between more narrowly specialized regions (e.g., fusiform gyrus or anterior temporal pole) and the thalamus for a larger sample of children and adolescents with ASD (N=37) compared to TD controls (N=38). Results : In the first study, we found evidence of both anatomical and functional underconnectivity between the prefrontal, parietal-occipital, motor, and somatosensory cortices with ipsilateral thalamus. The only exception was functional connectivity with the temporal lobe, which was increased in the ASD group, especially in the right hemisphere. Delving deeper into the specificity of these connections in the second study, we found that functional connectivity was atypically reduced in the ASD group for supramodal association cortices involved in higher-order cognition (e.g., language, face processing), but was increased for sensorimotor and limbic regions (e.g., auditory cortex). Discussions : Our findings provide evidence of regionally specific aberrations of thalamic connectivity in frontal and temporal lobes, with additional involvement of some parieto-occipital ROIs. These findings could be related to early maturation of limbic and sensorimotor regions in the context of early overgrowth in ASD, at the expense of thalamocortical connectivity with later maturing cortical regions.
Author: Rajesh K. Kana
Publisher: Frontiers E-books
ISBN: 2889192822
Category : Autism
Languages : en
Pages : 265
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The brain's ability to process information crucially relies on connectivity. Understanding how the brain processes complex information and how such abilities are disrupted in individuals with neuropsychological disorders will require an improved understanding of brain connectivity. Autism is an intriguingly complex neurodevelopmental disorder with multidimensional symptoms and cognitive characteristics. A biological origin for autism spectrum disorders (ASD) had been proposed even in the earliest published accounts (Kanner, 1943; Asperger, 1944). Despite decades of research, a focal neurobiological marker for autism has been elusive. Nevertheless, disruptions in interregional and functional and anatomical connectivity have been a hallmark of neural functioning in ASD. Theoretical accounts of connectivity perceive ASD as a cognitive and neurobiological disorder associated with altered functioning of integrative circuitry. Neuroimaging studies have reported disruptions in functional connectivity (synchronization of activated brain areas) during cognitive tasks and during task-free resting states. While these insights are valuable, they do not address the time-lagged causality and directionality of such correlations. Despite the general promise of the connectivity account of ASD, inconsistencies and methodological differences among studies call for more thorough investigations. A comprehensive neurological account of ASD should incorporate functional, effective, and anatomical connectivity measures and test the diagnostic utility of such measures. In addition, questions pertaining to how cognitive and behavioral intervention can target connection abnormalities in ASD should be addressed. This research topic of the Frontiers in Human Neuroscience addresses “Brain Connectivity in Autism” primarily from cognitive neuroscience and neuroimaging perspectives.
Author: Lisa Elena Mash
Publisher:
ISBN:
Category :
Languages : en
Pages : 143
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Autism spectrum disorder (ASD) is a behaviorally diagnosed neurodevelopmental condition that is associated with atypical functional connectivity (FC). However, no consistent biomarkers have been identified. Most studies to date have focused on static FC, and relatively little is known about time-varying properties of FC. This three-paper dissertation aimed to better characterize brain networks in ASD by evaluating: 1) transient connectivity states, 2) BOLD lag structure, and 3) associations between hemodynamic and electrophysiological measures of brain function. Study 1 (Mash et al., 2019) used sliding window analysis to examine FC variability and describe transient connectivity in children and adolescents (ages 6-18) with ASD (n=62) and their typically developing (TD) peers (n=57). Across all regions, the ASD group showed FC overconnectivity and hypervariability, on average. Distinct patterns of FC group differences were found in two transient states, but not in static FC analyses. Study 2 (Mash, et al., under review) explored resting-state and task-related BOLD lag structure in adolescents and young adults (ages 12-21) with ASD (n=28) and typical development (n=22). Lag patterns did not significantly differ between groups, with common 'early' and 'late' regions emerging in both groups. However, lag structure was associated with both task condition and vascular supply, suggesting a combination of neural and vascular contributions to BOLD latency. Study 3 (Mash et al., 2020) characterized relationships between separately acquired resting-state fMRI and EEG activity in a sample of children and adolescents (ages 6-18) with ASD and typical development (EEG-only: n=36 per group; fMRI-only: n=66 ASD, 57 TD; EEG-fMRI: n=17 per group). Reduced EEG alpha power, increased BOLD activity in right temporal regions, and widespread thalamocortical BOLD overconnectivity were observed in the ASD group. Multilevel modeling (with brain regions nested within individuals) revealed mostly positive relationships between EEG alpha power and regional BOLD activity in typical development, which were not observed in ASD. Overall, findings suggest that in comparison to conventional static FC studies, dynamic and multimodal analyses reveal more complex FC and activity patterns that may distinguish ASD from typical development.
Author:
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ISBN:
Category : Canals
Languages : en
Pages :
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Author:
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Category : Electronic books
Languages : en
Pages : 42
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Evidence indicates that Autism Spectrum Disorders (ASDs) involve atypical neural connectivity of multiple networks. Recent studies indicate atypical connectivity (structural and functional) between cortex and subcortex, including thalamo-cortical and cerebello-cortical connections. Those findings showed increased connectivity for somatomotor and limbic circuitry, but decreased connectivity for multimodal circuitry, possibly from overdevelopment of earlier maturing somatomotor and limbic cortico-subcortical circuits. We investigated structural connections between the cerebral cortex and striatum for a similar pattern of atypical structural connectivity, since the striatum has distinct inputs from the limbic, somatomotor, and multimodal domains. The striatum is crucial to motor function, reward systems, and higher order cognition, and is known to be affected in ASDs. We utilized archival MRI and behavioral data acquired as part of an ongoing study examining 49 children with ASDs and 49 typically developing (TD) children (7–17 years) matched on age, gender, non-verbal IQ, and in-scanner head motion. We examined structural connectivity between striatum and cortex using probabilistic diffusion tractography to estimate projections from the frontal lobe (limbic, somatomotor, and multimodal target regions) and posterior lobes to the striatum. Connectivity-based seed classification was performed to determine distribution of streamlines connecting with each of the cortical regions, creating a histogram map of the striatum. Hard segmentation was performed on the maps to classify each voxel based on the cortical region that had the highest number of streamlines in the participant’s maps, creating one image per subject where all targets were represented categorically. Probabilistic tractography revealed group differences in frontal limbic-striatal (mean diffusivity; ASD>TD) and temporo-striatal tracts (radial diffusivity; ASD>TD), as well as brain-behavior correlations in the ASD group (limbic-striatal tract with ADI social sub-scale, temporo-striatal tract with BRIEF II sub-scales). Seed classification analyses revealed group differences in the striatal distribution of somatomotor-striatal and temporo-striatal connections. Hard segmentation revealed a group difference (ASD>TD) in multimodal-striatal parcel volume, and correlation between the parieto-striatal parcel volume and the SRS awareness sub-scale in the ASD group. Overall, our results suggest that domain-specific patterns of structural connectivity of the striatum in ASDs may be distinct from patterns seen in the functional connectivity of the thalamus and cerebellum.
Author: Amanda Jewell Khan
Publisher:
ISBN:
Category :
Languages : en
Pages : 41
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The cerebellum is considered to play an important role in motor, somatosensory, and executive functioning. A number of studies have reported abnormalities in neuronal integrity, volume, metabolism, and activity in the cerebellum in autism spectrum disorders (ASD). A previous functional connectivity magnetic resonance imaging (fcMRI) study reported cerebro-cerebellar underconnectivity during motor performance in ASD. Resting-state (RS) fcMRI identifies spontaneous low-frequency blood oxygenation level dependent (BOLD) signal fluctuations allowing for the examination of intrinsic network connectivity. Impairments of motor, sociocommunicative, and executive functions have been reported in numerous studies of ASD. Such impairments may be associated with abnormal cerebellar connectivity with prefrontal, motor, somatosensory, auditory, and visual cortices. However, a systematic investigation of intrinsic cerebro-cerebellar connectivity for such networks in ASD is currently unavailable. In the present study, we investigated cerebro-cerebellar resting state functional connectivity in 50 adolescents aged 12-17 years. Using data acquired on a 3T GE Scanner, we performed partial and total correlations between each voxel in the contralateral cerebellar mask and the times series extracted from unilateral prefrontal (PFC), premotor/motor (PMC), somatosensory, superior temporal (STC), occipital, and inferior and middle temporal (IMT) regions of interest (ROI). ROIs were divided into two zones, supramodal (PFC, PPC, IMT) and sensorimotor (PMC, occipital, somatosensory, & STC). Additional correlational analyses were conducted for fcMRI effects with diagnostics, Social Responsiveness Scale (SRS), Visuo-Motor Integration (VMI), and Wechsler Abbreviated Scale of Intelligence (WASI) scores. We found a trend towards overconnectivity in sensorimotor ROIs accompanied by underconnectivity in supramodal ROIs in ASD compared to TD. There were significant positive and negative correlations with both supramodal and sensorimotor ROIs and ADOS, SRS, VMI, and WASI scores. The present study's cerebro-cerebellar findings suggest a possible expansion of sensorimotor-related cerebro-cerebellar connectivity at the expense of connectivity subserving supramodal functions, consistent with reports of executive impairments in ASD. Our study highlights the importance of examining cerebro-cerebellar resting state functional connectivity in ASD.
Author: John P. Hegarty (II)
Publisher:
ISBN:
Category :
Languages : en
Pages : 152
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The underlying neuropathology and effects on neuronal activity in individuals with ASD are still being elucidated as well as their impact on intervention and treatment outcomes. Frontal, temporal, parietal and cerebellar pathways exhibit disrupted structural and functional connectivity in individuals with ASD and we sought to investigate the potential clinical utility of altered network coherence. Beta-adrenergic antagonism improved information processing in a subset of individuals with ASD and improved performance was related to pharmacologically-mediated alterations in functional connectivity in the fronto-parietal control network. These findings support the potential utility of beta-adrenergic antagonists for some patients with ASD and the clinical significance of alterations in network coherence. There are also additional considerations for functional connectivity investigations in ASD. The cerebellum is interconnected via feedback loops to the neocortex and thus has some modulatory influences on cortical and subcortical neuronal circuits. The cerebellum is consistently implicated in the neuropathology of ASD but has been largely ignored in investigations of functional network coherence. Functional connectivity between the cerebellum and neocortex was anticorrelated in a subset of individuals with ASD. These individuals exhibited reduced glutamate levels in the cerebellum and diminished interpretive linguistic abilities, suggesting a potential mechanism underlying altered cerebrocerebellar connectivity in some individuals with ASD as well a cognitive outcome of alterations in cerebrocerebellar network coherence.
Author: Francesca Happé
Publisher: OUP Oxford
ISBN: 0199560145
Category : Art
Languages : en
Pages : 244
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"Originating from a theme issue first published in Philosophical transactions of the Royal Society. B, Biological sciences."
Author: Peter Mariën
Publisher: Academic Press
ISBN: 0128017856
Category : Medical
Languages : en
Pages : 446
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Book Description
The Linguistic Cerebellum provides a comprehensive analysis of this unique part of the brain that has the most number of neurons, each operating in distinct networks to perform diverse functions. This book outlines how those distinct networks operate in relation to non-motor language skills. Coverage includes cerebellar anatomy and function in relation to speech perception, speech planning, verbal fluency, grammar processing, and reading and writing, along with a discussion of language disorders. Discusses the neurobiology of cerebellar language functions, encompassing both normal language function and language disorders Includes speech perception, processing, and planning Contains cerebellar function in reading and writing Explores how language networks give insight to function elsewhere in the brain
