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Differential neural activation for updating rule versus stimulus information in working memory

NEURON 2008年第1期59卷 173-182页

作者： Montojo, Caroline A. Courtney, Susan M. Johns Hopkins Univ Dept Psychol & Brain Sci Baltimore MD 21218 USA Johns Hopkins Univ Dept Neurosci Baltimore MD 21218 USA Kennedy Krieger Inst FM Kirby Res Ctr Funct Brain Imaging Baltimore MD 21218 USA

Establishing what information is actively maintained in working memory (WM) and how it is represented and controlled is essential to understanding how such information guides future behavior. WM has traditionally been investigated in terms of the maintenance of stimulus-specific information, such as locations or words. More recently, investigators have emphasized the importance of rules that establish relationships between those stimuli and the pending response. The current study used a mental arithmetic task with fMRI to test whether updating of numbers (i.e., stimuli) and updating of mathematical operations (i.e., rules) in WM relies on the same neural system. Results indicate that, while a common network is activated by both types of updating, rule updating preferentially activates prefrontal cortex while number updating preferentially activates parietal cortex. The results suggest that both numbers and rules are maintained in WM but that they are different types of information that are controlled independently.

关键词： Adult Analysis of Variance Brain/blood supply Brain/physiology Brain Mapping Brain Mapping Female Humans image processing, computer-assisted/methods Magnetic Resonance Imaging Male Mathematics Memory, Short-Term/physiology Mental Processes/physiology Oxygen/blood Photic Stimulation/methods Reaction Time/physiology

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Optical analysis of computed tomography images of the liver predicts fibrosis stage and distribution in chronic hepatitis C

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HEPATOLOGY 2008年第3期47卷 810-816页

作者： Romero-Gomez, Manuel Gomez-Gonzalez, Emilio Madrazo, Ana Vera-Valencia, Marina Rodrigo, Luis Perez-Alvarez, Ramon Perez-Lopez, Rosa Castellano-Megias, Victor M. Nevado-Santos, Manuel Alcon, Juan C. Sola, Ricard Perez-Moreno, Jose M. Navarro, Jose M. Andrade, Raul J. Salmeron, Javier Fernandez-Lopez, Manuel Aznar, Rafael Diago, Moises Hosp Univ Valme Unit Clin Management Digest Dis Seville 41014 Spain Hosp Univ Valme CIBEREHD Seville 41014 Spain Univ Seville Dept Appl Phys 3 ESI Interdisciplinary Phys Grp Seville Spain Univ Oviedo Hosp Cent Asturias Digest Serv E-33080 Oviedo Spain Hosp Fuenlabrada Pathol Unit Madrid Spain Fdn Hosp Alcorcon Pathol Unit Madrid Spain Hosp Univ Valme Radiol Unit Seville 41014 Spain Hosp del Mar Hepatol Sect Barcelona Spain Hosp Univ Puerto Real Digest Unit Cadiz Spain Hosp Costa Sol Digest Unit Malaga Spain Hosp Virgen Victoria Hepatol Unit Malaga Spain Hosp Univ San Cecilio Digest Unit Granada Spain Univ Valencia Gen Hosp Hepatol Sect Valencia Spain

This study was undertaken to evaluate an image processing method for assessing liver fibrosis in conventional computed tomography (CT) scans in patients with chronic hepatitis C. Two cohorts (designated "estimation," n = 34;and "validation," n = 107) of chronic hepatitis C patients were assessed using digitized conventional helical CT. Weighted CT mean fibrosis (Fibro-CT) was calculated as a nonlinear weighted mean F-score for each sample. Fibrosis was defined according to Scheuer on the F0 to F4 scale by 2 pathologists blinded regarding the Fibro-CT data. Fibrosis according to Fibro-CT correlated with histology-determined fibrosis (r = 0.69;P < 0.001) and with increasing F-stage: FO = 0.23 +/- 0.39;F1 = 0.90 +/- 0.99;F2 = 1.41 +/- 0.94;F3 = 2.79 +/- 0.55;F4 = 3.15 +/- 0.35 [analysis of variance: P < 0.0001). The receiver operating characteristics curve to diagnose significant fibrosis (>= F2) was 0.83;95% confidence interval (95%CI), 0.75 to 0.91;and, to diagnose advanced fibrosis (>= F3), was 0.86, 95%CI: 0.80 to 0.93. The correlation between Fibro-CT and fibrosis was higher in patients with homogeneous distribution of fibrosis than in patients with heterogeneous distribution (r = 0.77 versus r = 0.43;P < 0.05). Conclusion: Optical digital analysis of CT images of the liver is effective in determining the stage and distribution of liver fibrosis in chronic hepatitis C. In patients with homogeneous fibrosis distribution, the correlation between Fibro-CT and histology was better than in patients with heterogeneous distribution. Fibro-CT is a simple to use, readily available, and useful method for the diagnosis of fibrosis in patients with chronic hepatitis C.

关键词： Adult Aged Cohort Studies Female Hepatitis C, Chronic/complications Hepatitis C, Chronic/pathology Humans image processing, computer-assisted/methods Liver Cirrhosis/pathology Liver Cirrhosis/radiography Liver Cirrhosis/virology Male Middle Aged Prognosis Tomography, X-Ray Computed/methods

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Laser scanning cytometry for automation of the micronucleus assay

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MUTAGENESIS 2011年第1期26卷 153-161页

作者： Darzynkiewicz, Zbigniew Smolewski, Piotr Holden, Elena Luther, Ed Henriksen, Mel Francois, Maxime Leifert, Wayne Fenech, Michael New York Med Coll Dept Pathol Valhalla NY 10595 USA Med Univ Lodz Copernicus Mem Hosp Dept Expt Hematol PL-95510 Lodz Poland CompuCyte Corp Westwood MA 02090 USA CSIRO Nutr Genom & DNA Damage Diagnost Res Grp Adelaide SA 5000 Australia Edith Cowan Univ Ctr Excellence Alzheimers Dis Joondalup WA 6027 Australia

Laser scanning cytometry (LSC) provides a novel approach for automated scoring of micronuclei (MN) in different types of mammalian cells, serving as a biomarker of genotoxicity and mutagenicity. In this review, we discuss the advances to date in measuring MN in cell lines, buccal cells and erythrocytes, describe the advantages and outline potential challenges of this distinctive approach of analysis of nuclear anomalies. The use of multiple laser wavelengths in LSC and the high dynamic range of fluorescence and absorption detection allow simultaneous measurement of multiple cellular and nuclear features such as cytoplasmic area, nuclear area, DNA content and density of nuclei and MN, protein content and density of cytoplasm as well as other features using molecular probes. This high-content analysis approach allows the cells of interest to be identified (e.g. binucleated cells in cytokinesis-blocked cultures) and MN scored specifically in them. MN assays in cell lines (e.g. the CHO cell MN assay) using LSC are increasingly used in routine toxicology screening. More high-content MN assays and the expansion of MN analysis by LSC to other models (i.e. exfoliated cells, dermal cell models, etc.) hold great promise for robust and exciting developments in MN assay automation as a high-content high-throughput analysis procedure.

关键词： Animals CHO Cells Cricetinae Cricetulus DNA/analysis Erythrocytes/ultrastructure Flow Cytometry/methods Flow Cytometry/methods Humans image processing, computer-assisted/methods Laser Scanning Cytometry/methods Laser Scanning Cytometry/methods Micronucleus Tests Mouth Mucosa/ultrastructure

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Pattern-information analysis: From stimulus decoding to computational-model testing

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NEUROimage 2011年第2期56卷 411-421页

作者： Kriegeskorte, Nikolaus MRC Cognit & Brain Sci Unit Cambridge CB2 7EF England

Pattern-information analysis has become an important new paradigm in functional imaging. Here I review and compare existing approaches with a focus on the question of what we can learn from them in terms of brain theory. The most popular and widespread method is stimulus decoding by response-pattern classification. This approach addresses the question whether activity patterns in a given region carry information about the stimulus category. Pattern classification uses generic models of the stimulus-response relationship that do not mimic brain information processing and treats the stimulus space as categorical a simplification that is often helpful, but also limiting in terms of the questions that can be addressed. We can address the question whether representations are consistent across different stimulus sets or tasks by cross-decoding, where the classifier is trained with one set of stimuli (or task) and tested with another. Beyond pattern classification, a major new direction is the integration of computational models of brain information processing into pattern-information analysis. This approach enables us to address the question to what extent competing computational models are consistent with the stimulus representations in a brain region. Two methods that test computational models are voxel receptive-field modeling and representational similarity analysis. These methods sample the stimulus (or mental-state) space more richly, estimate a separate response pattern for each stimulus, and can generalize from the stimulus sample to a stimulus population. Computational models that mimic brain information processing predict responses from stimuli. The reverse transform can be modeled to reconstruct stimuli from responses. Stimulus reconstruction is a challenging feat of engineering, but the implications of the results for brain theory are not always clear. Exploratory pattern analyses complement the confirmatory approaches mentioned so far and can reveal strong, u

关键词： Animals Brain/physiology computer Simulation Humans image processing, computer-assisted/methods Magnetic Resonance Imaging Pattern Recognition, Automated/methods

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Detection and automatic repair of nucleotide base-pair mutations by coherent light

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JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 2005年第41期127卷 14434-14438页

作者： Thanopulos, I Shapiro, M Univ British Columbia Dept Chem Vancouver BC V6T 1Z1 Canada Weizmann Inst Sci Dept Chem Phys IL-76100 Rehovot Israel

We show that phase-coherent optical techniques allow for the detection and automatic repair of mutations in nucleotide pairs. We demonstrate computationally that there is a laser pulse sequence that can detect the occurrence of a mutation caused by a double proton transfer between hydrogen-bonded nucleotide pairs and automatically repair it by converting the mutated nucleoticle pair to the nonmutated one. The specific system chosen for this demonstration is the hydrogen-bonded 2-pyridone-2-hydroxypyridine dimer at typical internucleotide distances, a well-established model for tautomeric acid base pairs.

关键词： Base Pairing/radiation effects computer Simulation DNA/chemistry DNA/radiation effects DNA Repair Hydrogen Bonding image processing, computer-assisted/methods Light Light Models, Chemical Mutation/radiation effects Nucleotides/chemistry Nucleotides/radiation effects Optics and Photonics Protons

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Quantifying the distribution of probes between subcellular locations using unsupervised pattern unmixing

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BIOINFORMATICS 2010年第12期26卷 i7-i12页

作者： Coelho, Luis Pedro Peng, Tao Murphy, Robert F. Carnegie Mellon Univ Lane Ctr Computat Biol Pittsburgh PA 15213 USA Carnegie Mellon Univ Ctr Bioimage informat Pittsburgh PA 15213 USA Carnegie Mellon Univ Joint Carnegie Mellon Univ Univ Pittsburgh Ph D Program Computat Biol Pittsburgh PA 15213 USA Carnegie Mellon Univ Dept Biomed Engn Pittsburgh PA 15213 USA Carnegie Mellon Univ Dept Biol Sci Pittsburgh PA 15213 USA Carnegie Mellon Univ Dept Machine Learning Pittsburgh PA 15213 USA Univ Freiburg Freiburg Inst Adv Studies D-79104 Freiburg Germany

Motivation: Proteins exhibit complex subcellular distributions, which may include localizing in more than one organelle and varying in location depending on the cell physiology. Estimating the amount of protein distributed in each subcellular location is essential for quantitative understanding and modeling of protein dynamics and how they affect cell behaviors. We have previously described automated methods using fluorescent microscope images to determine the fractions of protein fluorescence in various subcellular locations when the basic locations in which a protein can be present are known. As this set of basic locations may be unknown (especially for studies on a proteome-wide scale), we here describe unsupervised methods to identify the fundamental patterns from images of mixed patterns and estimate the fractional composition of them. methods: We developed two approaches to the problem, both based on identifying types of objects present in images and representing patterns by frequencies of those object types. One is a basis pursuit method (which is based on a linear mixture model), and the other is based on latent Dirichlet allocation (LDA). For testing both approaches, we used images previously acquired for testing supervised unmixing methods. These images were of cells labeled with various combinations of two organelle-specific probes that had the same fluorescent properties to simulate mixed patterns of subcellular location. Results: We achieved 0.80 and 0.91 correlation between estimated and underlying fractions of the two probes (fundamental patterns) with basis pursuit and LDA approaches, respectively, indicating that our methods can unmix the complex subcellular distribution with reasonably high accuracy.

关键词： Algorithms Fluorescent Dyes/analysis image processing, computer-assisted/methods Proteins/analysis Proteins/chemistry Subcellular Fractions/metabolism Subcellular Fractions/ultrastructure

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An approach to MRI-based dosimetry for transcranial magnetic stimulation

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NEUROimage 2007年第4期36卷 1171-1178页

作者： Hernandez-Garcia, Luis Lee, Sangwoo Grissom, William Funct MRI Lab Ann Arbor MI 48109 USA

A new MRI-based measurement of the magnetic vector field distribution generated by a transcranial magnetic stimulation (TMS) probe is introduced in this study. Projections of the static magnetic field produced by a DC current in a TMS probe onto the axis of the scanner's main field (B-0) can be measured using a conventional B-0 field-mapping technique. The remaining Cartesian components can then be calculated from projections obtained at different orientations of the sample and probe. The measured static field can then be scaled to calculate the effects of a dynamic TMS pulse. This article includes a study demonstrating the feasibility of this approach on a phantom and a human subject. (C) 2007 Elsevier Inc. All rights reserved.

关键词： Artifacts Brain Mapping/methods Brain Mapping/methods Cerebral Cortex/physiology computer Simulation Electromagnetic Fields Electromagnetic Fields Humans image processing, computer-assisted/methods Magnetic Resonance Imaging/methods Phantoms, Imaging Software Transcranial Magnetic Stimulation/methods

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Evaluation of intraocular foreign bodies by spiral computed tomography and multiplanar reconstruction

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OPHTHALMOLOGY 1998年第2期105卷 307-312页

作者： Lakits, A Steiner, E Scholda, C Kontrus, M Univ Vienna Dept Ophthalmol A-1090 Vienna Austria Univ Vienna Dept Radiol A-1090 Vienna Austria

Objective: This study aimed to evaluate the ability of spiral computed tomography (CT) and multiplanar reconstruction: in the assessment of intraocular foreign bodies. Design: The study design was experimental. Material: Three foreign bodies (metal, glass, and plastic) implanted into the globe of a cadaveric head were studied, Intervention: Spiral CT in the axial plane was used. Beam collimation and table increment were both 3 mm, whereby overlapping axial slices were reconstructed at 1-mm intervals, The data were transferred to a workstation, and reconstructions in the coronal and sagittal plane were performed. Main Outcome Measures: The ability to detect and evaluate localization, shape, and size of the foreign bodies in all three imaging planes was assessed. Results: All foreign bodies were detected in the axial and in both reconstructed planes, The metal foreign body caused imaging artifacts in the axial plane. In the reconstructed planes, imaging artifacts were less severe, and evaluation of localization and shape was improved. Glass and plastic foreign bodies were well seen in all planes, and shape and localization were well demonstrated, Appropriate window settings improved determination of size of the different foreign bodies. Conclusions: Spiral CT of the orbit and multiplanar reconstruction offers a promising tool for evaluation of intraocular foreign bodies. Advantages of spiral CT compared to conventional CT are data acquisition in only one axial plane;shortened examination time;reduced radiation exposure;reduced imaging artifacts from metallic foreign bodies in the reconstructed planes;and demonstration of localization, shape, and size of the foreign body in three imaging planes.

关键词： Eye Foreign Bodies/radiography Eye Foreign Bodies/radiography Glass Humans image processing, computer-assisted/methods Metals Models, Anatomic Orbit/radiography Plastics Tomography, X-Ray Computed/methods

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Mapping cortical gray matter asymmetry patterns in adolescents with heavy prenatal alcohol exposure

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NEUROimage 2002年第4期17卷 1807-1819页

作者： Sowell, ER Thompson, PM Peterson, BS Mattson, SN Welcome, SE Henkenius, AL Riley, EP Jernigan, TL Toga, AW Univ Calif Los Angeles Dept Neurol Lab Neuro Imaging Los Angeles CA 90095 USA Columbia Univ Coll Phys & Surg Dept Psychiat New York NY 10032 USA New York State Psychiat Inst & Hosp New York NY 10032 USA San Diego State Univ Ctr Behav Teratol San Diego CA 92120 USA Univ Calif San Diego Sch Med Dept Radiol La Jolla CA 92093 USA Univ Calif San Diego Sch Med Dept Psychiat La Jolla CA 92093 USA Univ Calif San Diego Sch Med Dept Vet Affairs Med Ctr La Jolla CA 92093 USA

Here we report on detailed three-dimensional quantitative maps of brain surface and gray matter density asymmetry patterns during normal adolescent development and show how these anatomical features of the brain are disrupted as a result of prenatal exposure to large quantities of alcohol. We studied two independent samples of normally developing children, adolescents, and young adults, totaling 83 subjects from two different research groups, and compared them to 21 individuals with heavy prenatal alcohol exposure. Surface-based image analysis techniques allowed us to match cortical anatomy across subjects and between hemispheres based on manually delineated sulcal landmarks. Quantitative maps of brain surface asymmetry reveal prominent peri-Sylvian hemispheric differences in which the superior temporal and inferior parietal cortices are shifted backward in the left relative to the right hemisphere in both normal and alcohol-exposed subjects. Cortical surface gray matter asymmetry, mapped here in adolescent populations, is most prominent in the posterior inferior temporal lobes (light greater than left), and this effect does not differ between groups of normally developing children, adolescents, or young adults. Alcohol-exposed individuals show a significant reduction in this asymmetry, whether studied with surface-based or more traditional volumetric region of interest analyses. This region of cortex, near the junction of Brodmann's areas 21, 22, and 37, primarily subserves language functions that are known to be impaired on average in the alcohol-exposed subjects. Our findings elucidate regional patterns of brain surface and gray matter asymmetry during normal development and may contribute to a more comprehensive understanding of the neural substrates of cognitive dysfunction after heavy prenatal alcohol exposure. (C) 2002 Elsevier Science (USA).

关键词： Adolescent Adult Brain Mapping/methods Brain Mapping/methods Cerebral Cortex/pathology Cerebral Cortex/physiopathology Child Dominance, Cerebral/physiology Female Fetal Alcohol Syndrome/diagnosis Fetal Alcohol Syndrome/pathology Fetal Alcohol Syndrome/physiopathology Humans image processing, computer-assisted/methods Imaging, Three-Dimensional/methods Magnetic Resonance Imaging/methods Male Pregnancy Reference Values

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Longitudinal and cross-sectional analysis of atrophy in Alzheimer's disease: Cross-validation of BSI, SIENA and SIENAX

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NEUROimage 2007年第4期36卷 1200-1206页

作者： Smith, Stephen M. Rao, Anil De Stefano, Nicola Jenkinson, Mark Schott, Jonathan M. Matthews, Paul M. Fox, Nick C. Univ Oxford Ctr Funct MRI Brain Oxford England GlaxoSmithKline Clin Imaging Ctr Hammersmith England Univ Siena Dept Neurol & Behav Sci I-53100 Siena Italy UCL Inst Neurol Dementia Res Ctr London WC1E 6BT England

Brain volume loss (atrophy) is widely used as a marker of disease progression. Atrophy has been measured with a variety of methods, some estimating atrophy rate from two temporally separated scans, and others estimating atrophy state from a single scan. Three popular tools for measuring brain atrophy are BSI and SIENA (rate) and SIENAX (state). Previous papers have shown BSI and SIENA to have similar accuracy, but no work has carefully compared both methods using the same data set. Here we compare these methods, using data from patients with Alzheimer's disease and age-matched controls. We also compare the SIENA longitudinal measure with atrophy state estimated by SIENAX using just the earliest scan taken from each subject. We show strong correspondence and similar sensitivity to atrophy between all 3 measures. (C) 2007 Elsevier Inc. All rights reserved.

关键词： Aged Alzheimer Disease/diagnosis Artifacts Artificial Intelligence Atrophy Brain/pathology Cerebral Ventricles/pathology Cross-Sectional Studies Female Humans image processing, computer-assisted/methods Longitudinal Studies Magnetic Resonance Imaging/methods Male Reference Values Sensitivity and Specificity Software

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