Publications by Year: 2010

We performed cerebellum segmentation and parcellation on magnetic resonance images from right-handed boys, aged 6-13 years, including 22 boys with autism [16 with language impairment (ALI)], 9 boys with Specific Language Impairment (SLI), and 11 normal controls. Language-impaired groups had reversed asymmetry relative to unimpaired groups in posterior-lateral cerebellar lobule VIIIA (right side larger in unimpaired groups, left side larger in ALI and SLI), contralateral to previous findings in inferior frontal cortex language areas. Lobule VIIA Crus I was smaller in SLI than in ALI. Vermis volume, particularly anterior I-V, was decreased in language-impaired groups. Language performance test scores correlated with lobule VIIIA asymmetry and with anterior vermis volume. These findings suggest ALI and SLI subjects show abnormalities in neurodevelopment of fronto-corticocerebellar circuits that manage motor control and the processing of language, cognition, working memory, and attention.

We present an advanced software tool designed for visualization and quantitative analysis of Diffusion Tensor Imaging (DTI) called Saturn. The software is specially developed to help clinicians and researchers in neuroimaging, and includes a complete set of visualization capabilities to browse and analyze efficiently DTI data, making this application a powerful tool also for diagnosis purposes. The software includes a robust quantification method for DTI data, using an atlas-based method to automatically obtain equivalent anatomical fiber bundles and regions of interest among different DTI data sets. Consequently, a set of measurements is also implemented to perform robust group studies among subjects affected by neurological disorders and control groups in order to look for significant differences. Finally, a comparison study with five similar DTI applications is presented, showing the advantages offered by this tool.

In this work, we propose to use fiber tracking in order to analyze and quantify the state of the pyramidal tracts in patients affected by tumors. We introduce a framework that includes an automatic method to obtain the fibers involved in the pyramidal tract of any subject, in order to compare robustly fiber bundles affected by tumors with healthy fiber tracts from control subjects and also to quantify the relative state of degeneration between the fiber tracts in the two hemispheres of the same patient. The comparative analyses proposed in our methodology are based on a new set of measures on the pyramidal tract, which take into account intrinsic properties of the fibers involved in the bundle as well as the similarity with the pyramidal tract of a standard healthy subject, modeled as the average of a set of controls. In order to perform better comparison studies and to take into account more information of the whole bundle, a mapping technique is used to represent the fiber tracts in 2D. Here, we show a set of experiments using 5 tumor patients and 10 control subjects, including pre- and post-operative studies in patients that have been treated with partial or total tumor resection. The results obtained indicate the usefulness of the method showing good overall performance. A reproducibility study using several acquisitions of the same patient is also presented to validate the techniques employed.

OBJECTIVE: We sought to examine preliminary results of brain alterations in anterior cingulate cortex (ACC) in treatment-na ıve adults with ADHD. The ACC is a central brain node for the integration of cognitive control and allocation of attention, affect and drive. Thus its anatomical alteration may give rise to impulsivity, hyperactivity and inattention, which are cardinal behavioral manifestations of ADHD.

First-degree relatives of persons with bipolar disorders (BDs) carry elevated risk for the illness, and manifest deficits in attention and memory (possible "endophenotypes"). However, there is only one published functional magnetic resonance imaging (fMRI) study of candidate endophenotypes in BD. We used fMRI to examine brain function in BD and in first-degree relatives performing a 2-back working memory (WM) task, and correlated brain activity with mood measures taken at the scanning session. Subjects (age 32-46) were 19 persons with BD, 18 unmedicated, non-psychotic first-degree relatives (RELs) of persons with BD, and 19 matched controls, ascertained from a long-term follow-up of a prenatal cohort study in New England. fMRI signal during 2-back and 0-back WM tasks was measured on a Siemens 1.5T MR scanner. fMRI data were analyzed using SPM-2. Persons with BD and RELs failed to suppress activation in the left anterior insula (BA 13) during WM, whereas controls suppressed activation. Compared to controls, RELs also failed to suppress activation in the orbitofrontal cortex (OFC) and superior parietal cortex. Controls and RELs exhibited greater activation than BD individuals in the left frontopolar cortex (BA 10) during WM. Results remained significant after controlling for confounders except for mild attenuation of OFC findings. Significant correlations between brain activity, mood, and WM suggest that activity in WM circuits is affected by activity in emotion-regulatory circuits. Persons with BD and RELs exhibit altered activity in the frontopolar cortex and insula, which may represent biomarkers of genetic risk for BD.

Although attention-deficit/hyperactivity disorder (ADHD) is associated both with brain alterations in attention and executive function (EF) circuitry and with genetic variations within the dopamine system (including the dopamine transporter gene [SLC6A3]), few studies have directly investigated how genetic variations are linked to brain alterations. We sought to examine how a polymorphism in the 3’ untranslated region (UTR) of SLC6A3, associated with ADHD in meta-analysis, might contribute to variation in dorsal anterior cingulate cortex (dACC) function in subjects with ADHD. We collected fMRI scans of 42 individuals with ADHD, all of European descent and over the age of 17, while they performed the multi-source interference task (MSIT), a cognitive task shown to activate dACC. SLC6A3 3’ UTR variable number tandem repeat (VNTR) polymorphisms were genotyped and brain activity was compared for groups based on allele status. ADHD individuals homozygous for the 10R allele showed significant hypoactivation in the left dACC compared to 9R-carriers. Exploratory analysis also showed trends toward hypoactivation in the 10R homozygotes in left cerebellar vermis and right lateral prefrontal cortex. Further breakdown of genotype groups showed similar activation in individuals heterozygous and homozygous for the 9R allele. Alterations in activation of attention and EF networks found previously to be involved in ADHD are likely influenced by SLC6A3 genotype. This genotype may contribute to heterogeneity of brain alterations found within ADHD samples.