Publications by authors named "Simon N Vandekar"

Background: The insula is a heterogeneous cortical region with three cytoarchitectural subregions-agranular, dysgranular, and granular-that have distinct functional roles. Previous cross-sectional studies have shown smaller volume of all insula subregions in individuals with psychotic disorders. However, longitudinal trajectories of insula subregions in early psychosis, and the relationship between subregional volumes and relevant clinical phenomena, such as perceptual aberrations, have not been previously examined.

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Spatially resolved molecular assays provide high dimensional genetic, transcriptomic, proteomic, and epigenetic information in situ and at various resolutions. Pairing these data across modalities with histological features enables powerful studies of tissue pathology in the context of an intact microenvironment and tissue structure. Increasing dimensions across molecular analytes and samples require new data science approaches to functionally annotate spatially resolved molecular data.

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Article Synopsis
  • The article discusses how the relationship between brain structure and function changes as individuals develop, potentially influencing the risk of neuropsychiatric disorders.
  • It highlights the need for better methods to examine individual differences in this structure-function relationship and introduces a new method called CIDeR aimed at reducing false positives in data analysis.
  • The authors demonstrate CIDeR's effectiveness through comparisons with existing methods and provide applications to brain development research using actual data from the Philadelphia Neurodevelopmental Cohort.
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Functional networks often guide our interpretation of spatial maps of brain-phenotype associations. However, methods for assessing enrichment of associations within networks of interest have varied in terms of both scientific rigor and underlying assumptions. While some approaches have relied on subjective interpretations, others have made unrealistic assumptions about spatial properties of imaging data, leading to inflated false positive rates.

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Hippocampal volume is smaller in schizophrenia, but it is unclear when in the illness the changes appear and whether specific regions (anterior, posterior) and subfields (CA1, CA2/3, dentate gyrus, subiculum) are affected. Here, we used a high-resolution T2-weighted sequence specialized for imaging hippocampal subfields to test the hypothesis that anterior CA1 volume is lower in early psychosis. We measured subfield volumes across hippocampal regions in a group of 90 individuals in the early stage of a non-affective psychotic disorder and 70 demographically similar healthy individuals.

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Many recent studies have demonstrated the inflated type 1 error rate of the original Gaussian random field (GRF) methods for inference of neuroimages and identified resampling (permutation and bootstrapping) methods that have better performance. There has been no evaluation of resampling procedures when using robust (sandwich) statistical images with different topological features (TF) used for neuroimaging inference. Here, we consider estimation of distributions TFs of a statistical image and evaluate resampling procedures that can be used when exchangeability is violated.

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Functional networks often guide our interpretation of spatial maps of brain-phenotype associations. However, methods for assessing enrichment of associations within networks of interest have varied in terms of both scientific rigor and underlying assumptions. While some approaches have relied on subjective interpretations, others have made unrealistic assumptions about the spatial structure of imaging data, leading to inflated false positive rates.

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Background: Hippocampal abnormalities are among the most consistent findings in schizophrenia. Numerous studies have reported deficits in hippocampal volume, function, and connectivity in the chronic stage of illness. While hippocampal volume and function deficits are also present in the early stage of illness, there is mixed evidence of both higher and lower functional connectivity.

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Background: Catatonia, a form of acute brain dysfunction typically linked with severe affective and psychotic disorders, occurs in critical illness with delirium and coma. Delirium and coma are associated with mortality, though catatonia's relationship with mortality is unclear. We aim to describe whether catatonia, delirium, and coma are associated with mortality.

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Study Purpose: Lower urinary tract symptoms (LUTS) can occur in chronic pain populations at high rates and drastically affect quality of life. Hypnosis is a nonpharmacological treatment used in chronic pain known to have beneficial implications to health outside of pain reduction. This study evaluated the potential for hypnosis to reduce LUTS in a sample of individuals with chronic pain, if baseline LUTS severity affected outcomes, and specific LUTS that may respond to hypnosis.

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With the increasing availability of neuroimaging data from multiple modalities-each providing a different lens through which to study brain structure or function-new techniques for comparing, integrating, and interpreting information within and across modalities have emerged. Recent developments include hypothesis tests of associations between neuroimaging modalities, which can be used to determine the statistical significance of intermodal associations either throughout the entire brain or within anatomical subregions or functional networks. While these methods provide a crucial foundation for inference on intermodal relationships, they cannot be used to answer questions about where in the brain these associations are most pronounced.

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Neuroimaging studies have revealed hippocampal hyperactivity in schizophrenia. In the early stage of the illness, hyperactivity is present in the anterior hippocampus and is thought to spread to other regions as the illness progresses. However, there is limited evidence for changes in basal hippocampal function following the onset of psychosis.

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Motivation: Multiplexed imaging is a nascent single-cell assay with a complex data structure susceptible to technical variability that disrupts inference. These in situ methods are valuable in understanding cell-cell interactions, but few standardized processing steps or normalization techniques of multiplexed imaging data are available.

Results: We implement and compare data transformations and normalization algorithms in multiplexed imaging data.

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Catatonia, characterized by motor, behavioral and affective abnormalities, frequently co-occurs with delirium during critical illness. Advanced age is a known risk factor for development of delirium. However, the association between age and catatonia has not been described.

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Many key findings in neuroimaging studies involve similarities between brain maps, but statistical methods used to measure these findings have varied. Current state-of-the-art methods involve comparing observed group-level brain maps (after averaging intensities at each image location across multiple subjects) against spatial null models of these group-level maps. However, these methods typically make strong and potentially unrealistic statistical assumptions, such as covariance stationarity.

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Background: Cross-sectional studies indicate that hippocampal function is abnormal across stages of psychosis. Neural theories of psychosis pathophysiology suggest that dysfunction worsens with illness stage. Here, we test the hypothesis that hippocampal function is impaired in the early stage of psychosis and declines further over the next 2 years.

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Objective: To examine the impact of educational materials for chronic overlapping pain conditions (COPCs), the feasibility of delivering materials online, and to explore its impact on self-reported self-management applications at 3-month follow-up.

Design: Prospective cohort study.

Setting: Online.

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The classical approach for testing statistical images using spatial extent inference (SEI) thresholds the statistical image based on the p-value. This approach has an unfortunate consequence on the replicability of neuroimaging findings because the targeted brain regions are affected by the sample size-larger studies have more power to detect smaller effects. Here, we use simulations based on the preprocessed Autism Brain Imaging Data Exchange (ABIDE) to show that thresholding statistical images by effect sizes has more consistent estimates of activated regions across studies than thresholding by p-values.

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Background: Individuals with autism spectrum disorder (ASD) often experience elevated stress during social interactions and may have difficulty forming and maintaining peer relationships. The autonomic nervous system (ANS) directs physiological changes in the body in response to a number of environmental stimuli, including social encounters. Evidence suggests the flexibility of the ANS response is an important driving factor in shaping social behavior.

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Relational memory, or the ability to form contextual associations among items encountered closely in time, is impaired in schizophrenia. The ability to bind items into a relational memory is dependent on the hippocampus, a region that is abnormal in schizophrenia. However, the hippocampus is also involved in exploratory behavior, leaving open the question whether relational memory deficits in schizophrenia are due to failure of relational binding or diminished visual exploration of individual items during encoding.

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Article Synopsis
  • Scientists are studying how the brain folds and if genetics affects this folding.
  • They found that local genetic influences, which are very small (less than 1 cm), play a big role in how thick parts of the brain are.
  • The way the brain folds is related to these local genetic factors, especially in areas important for movement and sensation, while it's less important in areas linked to thinking and decision-making.
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Brain iron is vital to multiple aspects of brain function, including oxidative metabolism, myelination, and neurotransmitter synthesis. Atypical iron concentration in the basal ganglia is associated with neurodegenerative disorders in aging and cognitive deficits. However, the normative development of brain iron concentration in adolescence and its relationship to cognition are less well understood.

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Objective: In schizophrenia, the anterior hippocampus is hyperactive and shows reduced task-related recruitment, but the relationship between these two findings is unclear. The authors tested the hypothesis that hyperactivity impairs recruitment of the anterior hippocampus during scene processing.

Methods: Functional MRI data from 45 early-psychosis patients and 35 demographically matched healthy control subjects were analyzed using a block-design 1-back scene-processing task.

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