Resting-state fMRI (rs-fMRI) holds promise as a clinical tool to characterize and monitor the phenotype of different neurological and psychiatric disorders. The most common analysis approach requires the definition of one or more regions-of-interest (ROIs). However this need for a priori ROI information makes rs-fMRI inadequate to survey functional connectivity differences associated with a range of neurological disorders where the ROI information may not be available. A second problem encountered in fMRI measures of connectivity is the need for an arbitrary correlation threshold to determine whether or not two areas are connected. This is problematic because in many cases the differences in tissue connectivity between disease groups and/or control subjects are threshold dependent. In this work we propose a novel voxel-based contrast mechanism for rs-fMRI, the Intrinsic Connectivity Distribution (ICD), that neither requires a priori information to define a ROI, nor an arbitrary threshold to define a connection. We show the sensitivity of previous methods to the choice of connection thresholds and evaluate ICD using a survey study comparing young adults born prematurely to healthy term control subjects. Functional connectivity differences were found in hypothesized language processing areas in the left temporal-parietal areas. In addition, significant clinically-relevant differences were found between preterm and term control subjects, highlighting the importance of whole brain surveys independent of a priori information.
Objective: Determine associations between left vocal cord paralysis (LVCP) and poor respiratory, feeding and/or developmental outcomes in extremely low birth weight (ELBW) infants following surgical closure of a patent ductus arteriosus (PDA).Study Design: ELBW infants who underwent PDA ligation between January 2004 and December 2006 were identified. We compared infants with and without LVCP following ligation to determine relationships between LVCP and respiratory morbidities, feeding and growth difficulties and neurodevelopmental impairment at 18 to 22-month follow-up. Student's t-test, Fisher's exact test and multivariable regression analyses were used to determine associations.Result: In all, 60 ELBW infants with a mean gestational age of 25 weeks and mean birth weight of 725 g had a PDA surgically closed. Twenty-two of 55 survivors (40%) were diagnosed with LVCP post-operatively. Infants with LVCP were significantly more likely to develop bronchopulmonary dysplasia (82 vs 39%, P ¼ 0.002), reactive airway disease (86 vs 33%, P<0.0001), or need for gastrostomy tube (63 vs 6%, P<0.0001).Conclusion: LVCP as a complication of surgical ductal ligation in ELBW infants is associated with persistent respiratory and feeding problems. Direct laryngoscopy should be considered for all infants who experience persistent respiratory and/or feeding difficulties following PDA ligation.
Background: Preclinical data demonstrate that gamma-aminobutyric acid (GABA) interneurons initiate connectivity in the developing brain. Objectives: The goal of this study was to compare GABA concentration and its relationship to functional connectivity in the brains of term and preterm infants at term-equivalent age. Methods: Infants received both magnetic resonance spectroscopy (MRS) and functional magnetic resonance imaging (fMRI) scans at term-equivalent age. Whole brain functional connectivity MRI data using intrinsic connectivity distribution maps were compared to identify areas with differences in resting-state functional connectivity between the preterm and term control groups. MRS measured concentrations of GABA, glutamate, N-acetyl-aspartate (NAA) and choline; NAA/choline was then calculated for comparison between the 2 groups. Results: Preterm infants had lower right frontal GABA and glutamate concentrations than term controls and showed a significantly different relationship between connectivity and GABA concentration in the right frontal lobe. Preterm infants had a positive correlation between GABA concentration and connectivity, while term controls demonstrated a negative correlation between these two developmentally regulated parameters. Conclusion: These results suggest that regional GABA concentrations are associated with normal and altered neonatal resting-state connectivity.
Preterm (PT) subjects are at risk for developmental delay, and task-based studies suggest that developmental disorders may be due to alterations in neural connectivity. Since emerging data imply the importance of right cerebellar function for language acquisition in typical development, we hypothesized that PT subjects would have alternate areas of cerebellar connectivity, and that these areas would be responsible for differences in cognitive outcomes between PT subjects and term controls at age 20 years. Nineteen PT and 19 term control young adults were prospectively studied using resting-state functional MRI (fMRI) to create voxel-based contrast maps reflecting the functional connectivity of each tissue element in the grey matter through analysis of the intrinsic connectivity contrast degree (ICC-d). Left cerebellar ICC-d differences between subjects identified a region of interest that was used for subsequent seed-based connectivity analyses. Subjects underwent standardized language testing, and correlations with cognitive outcomes were assessed. There were no differences in gender, hand preference, maternal education, age at study, or Peabody Picture Vocabulary Test (PPVT) scores. Functional connectivity (FcMRI) demonstrated increased tissue connectivity in the biventer, simple and quadrangular lobules of the L cerebellum (p<0.05) in PTs compared to term controls; seed-based analyses from these regions demonstrated alterations in connectivity from L cerebellum to both R and L inferior frontal gyri (IFG) in PTs compared to term controls. For PTs but not term controls, there were significant positive correlations between these connections and PPVT scores (R IFG: r=0.555, p=0.01; L IFG: r=0.454, p=0.05), as well as Verbal Comprehension Index (VCI) scores (R IFG: r=0.472, p=0.04). These data suggest the presence of a left cerebellar language circuit in PT subjects at young adulthood. These findings may represent either a delay in maturation or the engagement of alternative neural pathways for language in the developing PT brain.
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