Biomedical subjects

Jason Lerch

Publications and source records attributed to Jason Lerch.

7 recordsLinked to original sources

PubMed2006

Longitudinal mapping of cortical thickness and clinical outcome in children and adolescents with attention-deficit/hyperactivity disorder.

CONTEXT: Data from a previous prospective study of lobar volumes in children with attention-deficit/hyperactivity disorder (ADHD) are reexamined using a measure of cortical thickness. OBJECTIVE: To determine whether regional differences in cortical thickness or cortical changes across time characterize ADHD and predict or reflect its clinical outcome. DESIGN, SETTING, AND PARTICIPANTS: Longitudinal study of 163 children with ADHD (mean age at entry, 8.9 years) and 166 controls recruited mainly from a local community in Maryland. Participants were assessed with magnetic resonance imaging. Ninety-seven patients with ADHD (60%) had 2 or more images and baseline and follow-up clinical evaluations (mean follow-up, 5.7 years). MAIN OUTCOME MEASURES: Cortical thickness across the cerebrum. Patients with ADHD were divided into better and worse outcome groups on the basis of a mean split in scores on the Children's Global Assessment Scale and persistence/remission of DSM-IV-defined ADHD. RESULTS: Children with ADHD had global thinning of the cortex (mean reduction, -0.09 mm; P=.02), most prominently in the medial and superior prefrontal and precentral regions. Children with worse clinical outcome had a thinner left medial prefrontal cortex at baseline than the better outcome group (-0.38 mm; P=.003) and controls (-0.25 mm; P=.002). Cortical thickness developmental trajectories did not differ significantly between the ADHD and control groups throughout except in the right parietal cortex, where trajectories converged. This normalization of cortical thickness occurred only in the better outcome group. CONCLUSIONS: Children with ADHD show relative cortical thinning in regions important for attentional control. Children with a worse outcome have "fixed" thinning of the left medial prefrontal cortex, which may compromise the anterior attentional network and encumber clinical improvement. Right parietal cortex thickness normalization in patients with a better outcome may represent compensatory cortical change.

Adolescent↗

PubMed2006

Childhood onset schizophrenia: cortical brain abnormalities as young adults.

BACKGROUND: Childhood onset schizophrenia (COS) is a rare but severe form of the adult onset disorder. While structural brain imaging studies show robust, widespread, and progressive gray matter loss in COS during adolescence, there have been no longitudinal studies of sufficient duration to examine comparability with the more common adult onset illness. METHODS: Neuro-anatomic magnetic resonance scans were obtained prospectively from ages 7 through 26 in 70 children diagnosed with COS and age and sex matched healthy controls. Cortical thickness was measured at 40,962 points across the cerebral hemispheres using a novel, fully automated, validated method. Patterns of patient-control differences in cortical development were compared over a 19-year period. RESULTS: Throughout the age range, the COS group had significantly smaller mean cortical thickness compared to controls. However, the COS brain developmental trajectory appeared to normalize in posterior (parietal) regions, and remained divergent in the anterior regions (frontal and temporal) regions, and the pattern of loss became more like that seen in adults. CONCLUSIONS: Cortical thickness loss in COS appears to localize with age to prefrontal and temporal regions that are seen for both medication naïve and medicated adult onset patients.

Adolescent↗

PubMed2005

Automated 3-D extraction and evaluation of the inner and outer cortical surfaces using a Laplacian map and partial volume effect classification.

Accurate reconstruction of the inner and outer cortical surfaces of the human cerebrum is a critical objective for a wide variety of neuroimaging analysis purposes, including visualization, morphometry, and brain mapping. The Anatomic Segmentation using Proximity (ASP) algorithm, previously developed by our group, provides a topology-preserving cortical surface deformation method that has been extensively used for the aforementioned purposes. However, constraints in the algorithm to ensure topology preservation occasionally produce incorrect thickness measurements due to a restriction in the range of allowable distances between the gray and white matter surfaces. This problem is particularly prominent in pediatric brain images with tightly folded gyri. This paper presents a novel method for improving the conventional ASP algorithm by making use of partial volume information through probabilistic classification in order to allow for topology preservation across a less restricted range of cortical thickness values. The new algorithm also corrects the classification of the insular cortex by masking out subcortical tissues. For 70 pediatric brains, validation experiments for the modified algorithm, Constrained Laplacian ASP (CLASP), were performed by three methods: (i) volume matching between surface-masked gray matter (GM) and conventional tissue-classified GM, (ii) surface matching between simulated and CLASP-extracted surfaces, and (iii) repeatability of the surface reconstruction among 16 MRI scans of the same subject. In the volume-based evaluation, the volume enclosed by the CLASP WM and GM surfaces matched the classified GM volume 13% more accurately than using conventional ASP. In the surface-based evaluation, using synthesized thick cortex, the average difference between simulated and extracted surfaces was 4.6 +/- 1.4 mm for conventional ASP and 0.5 +/- 0.4 mm for CLASP. In a repeatability study, CLASP produced a 30% lower RMS error for the GM surface and a 8% lower RMS error for the WM surface compared with ASP.

Algorithms↗

PubMed2005

Comparing functional connectivity via thresholding correlations and singular value decomposition.

We compare two common methods for detecting functional connectivity: thresholding correlations and singular value decomposition (SVD). We find that thresholding correlations are better at detecting focal regions of correlated voxels, whereas SVD is better at detecting extensive regions of correlated voxels. We apply these results to resting state networks in an fMRI dataset to look for connectivity in cortical thickness.

Brain↗

PubMed2005

Changes in white matter in long-term survivors of severe non-missile traumatic brain injury: a computational analysis of magnetic resonance images.

The aim of this study was to investigate long-term consequences of severe non-missile traumatic brain injury (nmTBI) in patients without macroscopic focal brain lesions (>1.6 cm(3)) on regional white-matter density (WMd), and possible correlations with days of coma and memory performances. T1-weighted magnetic-resonance images (MRI) were acquired in 19 nmTBI patients, 3-113 months following the injury, and in 19 control subjects matched for age and gender. In addition, nmTBI patients underwent a battery of standardised memory tests. The MRIs were processed in a fully automatic system using voxel-by-voxel methods. Corpus callosum, fornix, anterior limb of the internal capsule, superior frontal gyrus, para-hippocampal gyrus, optic radiation and chiasma showed significant WMd reduction in nmTBI when compared to control subjects. None of the correlations between days of coma and memory performance scores with nmTBI voxels value that showed WMd reduction reached significance, with the exception of a significant negative correlation between WMd in the mid body of corpus callosum and short-story delayed recall. We detected reductions in WM density in several brain locations similar to those described in previous post mortem investigations. In addition, we observed WMd reduction in the optic chiasma and in the optic radiations; this finding may reflect transneural degeneration along the visual pathway. The weak correlations between specific anatomical sites of the reduced WMd and behavior may reflect the diffuse nature of the brain damage and/or the different time of onset between behavioral manifestations and neuropathological modifications occurring in nmTBI.

Adolescent↗

PubMed2004

Voxel-based morphometry of human brain with age and cerebrovascular risk factors.

The objectives of this study were to evaluate the correlations of the volumes of the gray matter and white matter with age, and the correlations of the tissue probabilities of the gray matter and white matter with age and several cerebrovascular risk factors. We obtained magnetic resonance (MR) images of the brain and clinical information from 769 normal Japanese subjects. We processed the MR images automatically by correcting for inter-individual differences in brain size and shape, and by segmenting the MR images into the gray matter and white matter. Volumetry of the brain revealed a significant negative correlation between the gray matter volume and age, which was not observed between white matter volume and age. Voxel-based morphometry showed that age, systolic blood pressure, and alcohol drinking correlated with the regional tissue probabilities of the gray matter and white matter.

Adolescent↗

PubMed2004

Unified univariate and multivariate random field theory.

We report new random field theory P values for peaks of canonical correlation SPMs for detecting multiple contrasts in a linear model for multivariate image data. This completes results for all types of univariate and multivariate image data analysis. All other known univariate and multivariate random field theory results are now special cases, so these new results present a true unification of all currently known results. As an illustration, we use these results in a deformation-based morphometry (DBM) analysis to look for regions of the brain where vector deformations of nonmissile trauma patients are related to several verbal memory scores, to detect regions of changes in anatomical effective connectivity between the trauma patients and a group of age- and sex-matched controls, and to look for anatomical connectivity in cortical thickness.

Adult↗