Atlas-based reconstruction of brain activation

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 151-161).Diffuse Optical Tomography (DOT) is a relatively new method used to image blood volume and oxygen saturation in vivo. Because of its relatively poor spatial resolution (typically no better than 1-2 cm), DOT is increasingly combined with other imaging techniques, such as MRI, fMRI and CT, which provide high-resolution structural information to guide the characterization of the unique physiological information offered by DOT. This work aims at improving DOT by offering new strategies for a more accurate, efficient, and faster image processor. Specifically, after investigating the influence of Cerebral Spinal Fluid (CSF) properties on the optical measurements, we propose using a realistic segmented head model that includes a novel CSF segmentation approach for a more accurate solution of the DOT forward problem. Moreover, we outline the benefits and applicability of a Diffusion Approximation-based faster forward model solver. We also describe a new registration algorithm based on superficial landmarks which is an essential tool for the purely optical tomographic image process proposed here. A purely optical tomography of the brain during neural activity will greatly enhance DOT applicability and provide many advantages, in the sense that DOT low cost, portability and non-invasiveness would be fully exploited without the compromises due to the MRI role in the DOT forward image process. We achieve a purely optical tomography by using a generalized head model (or atlas) in place of the subject specific anatomical MRI. We validate the proposed imaging protocol by comparing measurements derived from the DOT forward problem solution obtained using the subject specific anatomical model versus these acquired using the atlas registered to the subject, using a database of 31 healthy human. subjects, and focusing on a set of 12 functional regions of interest.(cont.) We conclude our study presenting data obtained from 3 experimental subjects having undergone median nerve stimuli. We apply our purely optical tomography protocol to the 3 subjects and analyze the observations derived from both the DOT forward and inverse solutions. The experimental results demonstrate that it is possible to guide the DOT forward problem with a general anatomical model in place of the subject's specific head geometry to localize the macro anatomical structures of neural activity.by Anna Custo.Sc.D

SnapShot: Cortical Development

Stem Cell and Regenerative Biolog

Molecular logic of neocortical projection neuron specification, development and diversity

The sophisticated circuitry of the neocortex is assembled from a diverse repertoire of neuronal subtypes generated during development under precise molecular regulation. In recent years, several key controls over the specification and differentiation of neocortical projection neurons have been identified. This work provides substantial insight into the 'molecular logic' underlying cortical development and increasingly supports a model in which individual progenitor-stage and postmitotic regulators are embedded within highly interconnected networks that gate sequential developmental decisions. Here, we provide an integrative account of the molecular controls that direct the progressive development and delineation of subtype and area identity of neocortical projection neurons.Stem Cell and Regenerative Biolog

Anatomical atlas-guided diffuse optical tomography of brain activation

We describe a neuroimaging protocol that utilizes an anatomical atlas of the human head to guide diffuse optical tomography of human brain activation. The protocol is demonstrated by imaging the hemodynamic response to median-nerve stimulation in three healthy subjects, and comparing the images obtained using a head atlas with the images obtained using the subject-specific head anatomy. The results indicate that using the head atlas anatomy it is possible to reconstruct the location of the brain activation to the expected gyrus of the brain, in agreement with the results obtained with the subject-specific head anatomy. The benefits of this novel method derive from eliminating the need for subject-specific head anatomy and thus obviating the need for a subject-specific MRI to improve the anatomical interpretation of diffuse optical tomography images of brain activation.National Institutes of Health (U.S.) (U54-EB-005149)National Institutes of Health (U.S.) (P41-RR14075)National Institutes of Health (U.S.) (P41-RR13218

Brenner tumour : the rare malignant variant

Brenner tumours were first described by MacNoughton Jones in 1898 in his paper ‘Uterine fibroid with anomalous ovarian tumour.’ In 1907, Fritz Brenner published his article ‘Des oophorona folliculare’ because of the resemblance of the epithelioid nests that Brenner found in his tumour, to Graafian follicles. The semblance to Graafian follicles underpinned Fritz Brenner’s classification of Brenner tumours as a variant of granulosa cell tumour. In 1932, Meyer, revisited the topic of Brenner tumours and clarified that they are different from granulosa cell tumours. However, Brenner became aware of such a publication, 24 years later and did not publish any other articles on this subject.peer-reviewe

Validating a new methodology for optical probe design and image registration in fNIRS studies

Functional near-infrared spectroscopy (fNIRS) is an imaging technique that relies on the principle of shining near-infrared light through tissue to detect changes in hemodynamic activation. An important methodological issue encountered is the creation of optimized probe geometry for fNIRS recordings. Here, across three experiments, we describe and validate a processing pipeline designed to create an optimized, yet scalable probe geometry based on selected regions of interest (ROIs) from the functional magnetic resonance imaging (fMRI) literature. In experiment 1, we created a probe geometry optimized to record changes in activation from target ROIs important for visual working memory. Positions of the sources and detectors of the probe geometry on an adult head were digitized using a motion sensor and projected onto a generic adult atlas and a segmented head obtained from the subject's MRI scan. In experiment 2, the same probe geometry was scaled down to fit a child's head and later digitized and projected onto the generic adult atlas and a segmented volume obtained from the child's MRI scan. Using visualization tools and by quantifying the amount of intersection between target ROIs and channels, we show that out of 21 ROIs, 17 and 19 ROIs intersected with fNIRS channels from the adult and child probe geometries, respectively. Further, both the adult atlas and adult subject-specific MRI approaches yielded similar results and can be used interchangeably. However, results suggest that segmented heads obtained from MRI scans be used for registering children's data. Finally, in experiment 3, we further validated our processing pipeline by creating a different probe geometry designed to record from target ROIs involved in language and motor processing

Exploiting electron storage in TiO2 nanoparticles for dark reduction of As(v) by accumulated electrons

UV irradiation of an ethanolic sol of TiO2 nanoparticles produces a trapped Ti(III) centre and a noticeable Burstein shift. Direct evidence that the accumulated charges can drive the otherwise forbidden reduction of As(V) by conduction band electrons is presented.Fil: Levy, Ivana Karina. Comision Nacional de Energia Atomica. Gerencia Quimica. CAC; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires; ArgentinaFil: Brusa, Marta Adelina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; ArgentinaFil: Aguirre, Matías Ezequiel. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; ArgentinaFil: Custo, Graciela. Comision Nacional de Energia Atomica. Gerencia Quimica. CAC; ArgentinaFil: San Roman, Enrique Arnoldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de Los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires; ArgentinaFil: Litter, Marta Irene. Comision Nacional de Energia Atomica. Gerencia Quimica. CAC; ArgentinaFil: Grela, Maria Alejandra. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentin

Metal determination in the dairy chain by TXRF

Numerosos metales son necesarios en niveles bajos para el funcionamiento normal de los organismos vivos; sin embargo, algunos pueden ser muy tóxicos. Diversas fuentes pueden aportar contaminantes que afecten la calidad de la leche. El objetivo de este trabajo fue la determinación cuali- cuantitativa de metales en la cadena de producción de leche de tres tambos de la Provincia de Buenos Aires.Facultad de Ciencias Agrarias y Forestale

(Anais do) Seminário "O Protesto e sua Central de Serviços como Instrumentos de Redução do Custo de Crédito"

Divulgação dos SUMÁRIOS das obras recentemente incorporadas ao acervo da Biblioteca Ministro Oscar Saraiva do STJ. Em respeito à Lei de Direitos Autorais, não disponibilizamos a obra na íntegra.Localização na estante: 347.735(81)(061.3) S471

Visual processing deficits in 22q11.2 Deletion Syndrome.

Carriers of the rare 22q11.2 microdeletion present with a high percentage of positive and negative symptoms and a high genetic risk for schizophrenia. Visual processing impairments have been characterized in schizophrenia, but less so in 22q11.2 Deletion Syndrome (DS). Here, we focus on visual processing using high-density EEG and source imaging in 22q11.2DS participants (N = 25) and healthy controls (N = 26) with an illusory contour discrimination task. Significant differences between groups emerged at early and late stages of visual processing. In 22q11.2DS, we first observed reduced amplitudes over occipital channels and reduced source activations within dorsal and ventral visual stream areas during the P1 (100-125 ms) and within ventral visual cortex during the N1 (150-170 ms) visual evoked components. During a later window implicated in visual completion (240-285 ms), we observed an increase in global amplitudes in 22q11.2DS. The increased surface amplitudes for illusory contours at this window were inversely correlated with positive subscales of prodromal symptoms in 22q11.2DS. The reduced activity of ventral and dorsal visual areas during early stages points to an impairment in visual processing seen both in schizophrenia and 22q11.2DS. During intervals related to perceptual closure, the inverse correlation of high amplitudes with positive symptoms suggests that participants with 22q11.2DS who show an increased brain response to illusory contours during the relevant window for contour processing have less psychotic symptoms and might thus be at a reduced prodromal risk for schizophrenia