Publications by authors named "Sheila Shanmugan"

Article Synopsis
  • * Using data from over 6,000 youths, researchers applied advanced analytical techniques to identify and classify sex differences in personalized functional networks.
  • * Findings reveal that significant differences exist in brain network topography related to sex, particularly in specific brain networks, and these differences correlate with the expression of certain genes, especially X-linked genes.
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Recent work has leveraged massive datasets and advanced harmonization methods to construct normative models of neuroanatomical features and benchmark individuals' morphology. However, current harmonization tools do not preserve the effects of biological covariates including sex and age on features' variances; this failure may induce error in normative scores, particularly when such factors are distributed unequally across sites. Here, we introduce a new extension of the popular ComBat harmonization method, ComBatLS, that preserves biological variance in features' locations and scales.

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Background: Symptoms of borderline personality disorder (BPD) often manifest during adolescence, but the underlying relationship between these debilitating symptoms and the development of functional brain networks is not well understood. Here, we aimed to investigate how multivariate patterns of functional connectivity are associated with borderline personality traits in large samples of young adults and adolescents.

Methods: We used functional magnetic resonance imaging data from young adults and adolescents from the HCP-YA (Human Connectome Project Young Adult) (n = 870, ages 22-37 years, 457 female) and the HCP-D (Human Connectome Project Development) (n = 223, ages 16-21 years, 121 female).

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Individual differences in cognition during childhood are associated with important social, physical, and mental health outcomes in adolescence and adulthood. Given that cortical surface arealization during development reflects the brain's functional prioritization, quantifying variation in the topography of functional brain networks across the developing cortex may provide insight regarding individual differences in cognition. We test this idea by defining personalized functional networks (PFNs) that account for interindividual heterogeneity in functional brain network topography in 9-10 year olds from the Adolescent Brain Cognitive Development℠ Study.

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Functional neuroimaging is an essential tool for neuroscience research. Pre-processing pipelines produce standardized, minimally pre-processed data to support a range of potential analyses. However, post-processing is not similarly standardized.

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Background |: Symptoms of borderline personality disorder (BPD) often manifest in adolescence, yet the underlying relationship between these debilitating symptoms and the development of functional brain networks is not well understood. Here we aimed to investigate how multivariate patterns of functional connectivity are associated with symptoms of BPD in a large sample of young adults and adolescents.

Methods |: We used high-quality functional Magnetic Resonance Imaging (fMRI) data from young adults from the Human Connectome Project: Young Adults (HCP-YA; = 870, ages 22-37 years, 457 female) and youth from the Human Connectome Project: Development (HCP-D; = 223, age range 16-21 years, 121 female).

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Prior work has shown that there is substantial interindividual variation in the spatial distribution of functional networks across the cerebral cortex, or functional topography. However, it remains unknown whether there are sex differences in the topography of individualized networks in youth. Here, we leveraged an advanced machine learning method (sparsity-regularized non-negative matrix factorization) to define individualized functional networks in 693 youth (ages 8 to 23 y) who underwent functional MRI as part of the Philadelphia Neurodevelopmental Cohort.

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Background: The spatial layout of large-scale functional brain networks differs between individuals and is particularly variable in the association cortex, implicated in a broad range of psychiatric disorders. However, it remains unknown whether this variation in functional topography is related to major dimensions of psychopathology in youth.

Methods: The authors studied 790 youths ages 8 to 23 years who had 27 minutes of high-quality functional magnetic resonance imaging data as part of the Philadelphia Neurodevelopmental Cohort.

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The brain is organized into networks at multiple resolutions, or scales, yet studies of functional network development typically focus on a single scale. Here, we derive personalized functional networks across 29 scales in a large sample of youths (n = 693, ages 8-23 years) to identify multi-scale patterns of network re-organization related to neurocognitive development. We found that developmental shifts in inter-network coupling reflect and strengthen a functional hierarchy of cortical organization.

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Many women with no history of cognitive difficulties experience executive dysfunction during menopause. Significant adversity during childhood negatively impacts executive function into adulthood and may be an indicator of women at risk of a mid-life cognitive decline. Previous studies have indicated that alterations in functional network connectivity underlie these negative effects of childhood adversity.

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Objective: Despite the fact that negative mood and executive dysfunction are common after risk-reducing salpingo-oophorectomy (RRSO), occurring in up to a third of women, little is known about risk factors predicting these negative outcomes. Adverse childhood experiences (ACE) predict poorer health in adulthood and may be a risk factor for negative outcomes after RRSO. Given the complex relationship between early life stress, affective disorders, and cognitive dysfunction, we hypothesized that ACE would be associated with poorer executive function and that mood symptoms would partially mediate this relationship.

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During the menopause transition, women are at increased risk of subjective symptoms of executive dysfunction. Evidence from animal and human participant studies suggests adverse childhood experiences (ACE) may be a risk factor for executive complaints during this hormonal transition. Preclinical literature indicates early life adversity effects on serotonin function may play a role in this increased susceptibility.

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Many healthy women with no history of cognitive dysfunction experience subjective executive difficulties during menopause. Preclinical literature suggests latent effects of early life adversity on serotonin function may play a role in this phenomenon. However, evidence in human participants regarding the mechanisms by which loss of estradiol contributes to this vulnerability is lacking.

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Many women with no history of executive dysfunction report difficulties in this domain during the menopause transition. Lisdexamfetamine (LDX) has been suggested to be a safe and effective treatment option for these women. However, the mechanism by which LDX improves executive functioning in these women is not known.

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Executive functions are involved in the development of academic skills and are critical for functioning in school settings. The relevance of executive functions to education begins early and continues throughout development, with clear impact on achievement. Diverse efforts increasingly suggest ways in which facilitating development of executive function may be used to improve academic performance.

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Objective: Disruption of executive function is present in many neuropsychiatric disorders. However, determining the specificity of executive dysfunction across these disorders is challenging given high comorbidity of conditions. Here the authors investigate executive system deficits in association with dimensions of psychiatric symptoms in youth using a working memory paradigm.

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Rationale: Reports of cognitive decline, particularly in the domains of executive functions (EFs), are common among menopausal women.

Objective: This study aims to determine the impact of the psychostimulant lisdexamfetamine (LDX) on subjective and objective cognitive function among menopausal women who report new-onset EF complaints.

Methods: Thirty-two healthy perimenopausal and early postmenopausal women experiencing mid-life-onset executive function difficulties as measured using the Brown Attention Deficit Disorder Scale (BADDS) were administered LDX 40-60 mg/day for 4 weeks in this double-blind, placebo-controlled, cross-over study.

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Midlife decline in cognition, specifically in areas of executive functioning, is a frequent concern for which menopausal women seek clinical intervention. The dependence of executive processes on prefrontal cortex function suggests estrogen effects on this brain region may be key in identifying the sources of this decline. Recent evidence from rodent, nonhuman primate, and human subject studies indicates the importance of considering interactions of estrogen with neurotransmitter systems, stress, genotype, and individual life events when determining the cognitive effects of menopause and estrogen therapy.

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