Defining functional areas in individual human brains using resting functional connectivity MRI

The cerebral cortex is anatomically organized at many physical scales starting at the level of single neurons and extending up to functional systems. Current functional magnetic resonance imaging (fMRI) studies often focus at the level of areas, networks, and systems. Except in restricted domains, (e.g., topographically-organized sensory regions), it is difficult to determine area boundaries in the human brain using fMRI. The ability to delineate functional areas non-invasively would enhance the quality of many experimental analyses allowing more accurate across-subject comparisons of independently identified functional areas. Correlations in spontaneous BOLD activity, often referred to as resting state functional connectivity (rs-fcMRI), are especially promising as a way to accurately localize differences in patterns of activity across large expanses of cortex. In the current report, we applied a novel set of image analysis tools to explore the utility of rs-fcMRI for defining wide-ranging functional area boundaries. We find that rs-fcMRI patterns show sharp transitions in correlation patterns and that these putative areal boundaries can be reliably detected in individual subjects as well as in group data. Additionally, combining surface-based analysis techniques with image processing algorithms allows automated mapping of putative areal boundaries across large expanses of cortex without the need for prior information about a region's function or topography. Our approach reliably produces maps of bounded regions appropriate in size and number for putative functional areas. These findings will hopefully stimulate further methodological refinements and validations.     

Alzheimer's disease diagnosis in individual subjects using structural MR images: validation studies

OBJECTIVE: To develop and validate a tool for Alzheimer's disease (AD) diagnosis in individual subjects using support vector machine (SVM)-based classification of structural MR (sMR) images. BACKGROUND: Libraries of sMR scans of clinically well characterized subjects can be harnessed for the purpose of diagnosing new incoming subjects. METHODS: One hundred ninety patients with probable AD were age- and gender-matched with 190 cognitively normal (CN) subjects. Three different classification models were implemented: Model I uses tissue densities obtained from sMR scans to give STructural Abnormality iNDex (STAND)-score; and Models II and III use tissue densities as well as covariates (demographics and Apolipoprotein E genotype) to give adjusted-STAND (aSTAND)-score. Data from 140 AD and 140 CN were used for training. The SVM parameter optimization and training were done by four-fold cross validation (CV). The remaining independent sample of 50 AD and 50 CN was used to obtain a minimally biased estimate of the generalization error of the algorithm. RESULTS: The CV accuracy of Model II and Model III aSTAND-scores was 88.5% and 89.3%, respectively, and the developed models generalized well on the independent test data sets. Anatomic patterns best differentiating the groups were consistent with the known distribution of neurofibrillary AD pathology. CONCLUSIONS: This paper presents preliminary evidence that application of SVM-based classification of an individual sMR scan relative to a library of scans can provide useful information in individual subjects for diagnosis of AD. Including demographic and genetic information in the classification algorithm slightly improves diagnostic accuracy.     

Agreement of measures obtained radiographically and by the OSI CA-6000 Spine Motion Analyzer for cervical spinal motion

The purpose of this study was to determine the agreement between angular measures of cervical spinal motion obtained from radiographs and from measures recorded by the OSI CA 6000 Spine Motion Analyzer (OSI SMA) in asymptomatic subjects. Fourteen subjects performed each of the following motions two times while wearing the OSI SMA: cervical flexion, extension, side bending to the right and left. Each motion was performed once for the cervical radiograph. The difference between the values obtained by the two methods was plotted against the average of those values for each subject to illustrate the level of agreement of the two methods. The plotted points were widely scattered, with a large range between the limits of agreement. Range of motion values taken from the OSI SMA were not similar to those obtained from radiographs for the motions of the cervical spine.     

Sequential combination therapy leads to biochemical and histological improvement despite low ongoing intrahepatic hepatitis B virus replication

BACKGROUND: We previously reported that 48 weeks of combination therapy with pegylated interferon-alpha2b (PEG-IFN-alpha2b) and adefovir dipivoxil (ADV) in patients with chronic hepatitis B led to marked decreases of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) (-2.4 log10 copies/ml). Combination therapy was followed by 96 weeks of ADV monotherapy. METHODS: Here, we report on the final outcome after 144 weeks of sequential antiviral treatment. Twenty-four patients were analysed, triplet liver biopsies (taken at baseline, week 48 and week 144) were available from 16 patients. RESULTS: At week 144, 12/15 patients positive for hepatitis B virus e antigen (HBeAg) had lost HBeAg, alanine transaminase (ALT) levels were normal in 23 patients (96%), median serum HBV DNA had decreased by -4.9 log10 copies/ml and was undetectable (<100 copies/ml) in 11/24 individuals (46%). Median total intrahepatic HBV DNA had decreased by -2.2 log. Although no further significant cccDNA changes occurred between week 48 and week 144, two years of ADV monotherapy proved capable of controlling cccDNA levels in most patients. Analysis of intrahepatic HBV DNA species demonstrated that combination therapy with PEG-IFN-alpha2b and ADV inhibited viral productivity by 99% and subsequent ADV monotherapy by 76%, respectively. Virus suppression to undetectability within the first 12 weeks of treatment was strongly associated with long-term virological response and HBeAg and hepatitis B virus surface antigen HBsAg seroconversion. Histological improvement was determined in 11/16 patients at week 144. Two patients developed ADV resistance during the third year of treatment. CONCLUSIONS: Reduction of intrahepatic viral load achieved after 48 weeks of combination therapy with PEG-IFN-alpha2b and ADV was maintained in the following 96 weeks of ADV monotherapy and translated into long-term clinical benefit for most of the treated patients.     

Sumatriptan does not affect arteriovenous oxygen differences in jugular and cubital veins in normal human subjects

Arteriovenous anastomoses (AVAs) may open up during migraine attacks. In studies with anaesthetized and bilaterally vagosympatectomized pigs, triptans reduce AVA blood flow and increase the arteriovenous O2 difference (AVDO2). To investigate whether subcutaneous sumatriptan 6 mg could induce changes in the AVDO2, we measured the AVDO2 in the external jugular vein in healthy subjects. We also measured the AVDO2 in the internal jugular and cubital veins. There were no changes in AVDO2 after subcutaneous sumatriptan, probably because AVA blood flow is limited in humans with an intact sympathetic nervous system.     

Temporal lobar predominance of TDP-43 neuronal cytoplasmic inclusions in Alzheimer disease

TAR DNA binding protein-43 (TDP-43) immunoreactive neuronal inclusions are detected in 20-30% of Alzheimer disease (AD) brains, but the distribution of this pathology has not been rigorously studied. In this report, we describe region-specific distribution and density of TDP-43 positive neuronal cytoplasmic inclusions (NCIs) in clinically demented individuals with high probability AD pathology, all with Braak neurofibrillary tangle stages of V or VI. Sections of hippocampus, amygdala, as well as temporal, frontal, and parietal neocortex, were analyzed with TDP-43 immunohistochemistry, and the density of NCIs was assessed using a semiquantitative scoring method. Of the 29 cases, six had TDP-43 positive NCIs in the amygdala only and seven had TDP-43 inclusions restricted to amygdala and hippocampus. In 16 cases, TDP-43 immunoreactivity was more widespread, affecting temporal, frontal or parietal neocortex. These findings indicate that medial temporal lobe limbic structures are vulnerable to TDP-43 pathology in advanced AD, and that the amygdala appears to be the most susceptible region. The distribution of the lesions in this cross-sectional analysis may suggest a progression of TDP-43 pathology in AD, with limbic structures in the medial temporal lobe affected first, followed by higher order association cortices.