50 research outputs found

    Accurate skull modeling for EEG source imaging

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    Proceedings of the Third International Workshop on Mathematical Foundations of Computational Anatomy - Geometrical and Statistical Methods for Modelling Biological Shape Variability

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    International audienceComputational anatomy is an emerging discipline at the interface of geometry, statistics and image analysis which aims at modeling and analyzing the biological shape of tissues and organs. The goal is to estimate representative organ anatomies across diseases, populations, species or ages, to model the organ development across time (growth or aging), to establish their variability, and to correlate this variability information with other functional, genetic or structural information. The Mathematical Foundations of Computational Anatomy (MFCA) workshop aims at fostering the interactions between the mathematical community around shapes and the MICCAI community in view of computational anatomy applications. It targets more particularly researchers investigating the combination of statistical and geometrical aspects in the modeling of the variability of biological shapes. The workshop is a forum for the exchange of the theoretical ideas and aims at being a source of inspiration for new methodological developments in computational anatomy. A special emphasis is put on theoretical developments, applications and results being welcomed as illustrations. Following the successful rst edition of this workshop in 20061 and second edition in New-York in 20082, the third edition was held in Toronto on September 22 20113. Contributions were solicited in Riemannian and group theoretical methods, geometric measurements of the anatomy, advanced statistics on deformations and shapes, metrics for computational anatomy, statistics of surfaces, modeling of growth and longitudinal shape changes. 22 submissions were reviewed by three members of the program committee. To guaranty a high level program, 11 papers only were selected for oral presentation in 4 sessions. Two of these sessions regroups classical themes of the workshop: statistics on manifolds and diff eomorphisms for surface or longitudinal registration. One session gathers papers exploring new mathematical structures beyond Riemannian geometry while the last oral session deals with the emerging theme of statistics on graphs and trees. Finally, a poster session of 5 papers addresses more application oriented works on computational anatomy

    Experience Dependent Plasticity over short and long timescales

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    The brain is constantly changing. Genetically specified developmental pathways interact with extrinsic factors including illness, injury and learning to shape the brain. This thesis presents two projects on experience dependent plasticity over different timescales. Exerting its effect across years, deafness provides a model of long term crossmodal plasticity. In the first part of this thesis I ask how deafness affects the thalamus. Diffusion weighted imaging was used to segment the thalamus and with probabilistic tractography, thalamo-cortical connections were traced. Microstructural properties of visual and frontal thalamic segmentations, thalamo-cortical tracts throughout the brain, apart from the temporal thalamo-cortical tract were altered. The neuroanatomical sequelae of deafness are evident throughout the brain. Deaf people have enhanced peripheral vision, facilitating a protective orienting mechanism when hearing cannot be relied upon. Widefield population receptive field (pRF) modeling with fMRI was completed to examine the functional and structural properties of primary visual cortex. Deaf participants had enlarged pRF profiles and thinner cortex in peripheral visual regions, again emphasizing plasticity across many years. In the second part I examine plasticity over the course of days. Visuomotor transformations translate visual input to motor actions, and its neural instantiation might change with training. We used a pattern component model on fMRI data to reveal a gradient of visual to motor information from occipital to parietal to motor cortex. Strikingly, we observed motor coding in visual cortex and visual coding in motor cortex. More tentatively, our results suggest that during sensorimotor skill learning there is decreased dependence on visual cortex as motor cortex learns the novel visuomotor mapping. In summary, I show crossmodal processing and plasticity in regions previously considered not to exhibit these properties, both in long- and short-term plasticity. This work emphasizes the contribution that computational neuroimaging can provide to the field of experience dependent plasticity

    NASA thesaurus. Volume 1: Hierarchical Listing

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    There are over 17,000 postable terms and nearly 4,000 nonpostable terms approved for use in the NASA scientific and technical information system in the Hierarchical Listing of the NASA Thesaurus. The generic structure is presented for many terms. The broader term and narrower term relationships are shown in an indented fashion that illustrates the generic structure better than the more widely used BT and NT listings. Related terms are generously applied, thus enhancing the usefulness of the Hierarchical Listing. Greater access to the Hierarchical Listing may be achieved with the collateral use of Volume 2 - Access Vocabulary and Volume 3 - Definitions

    NASA Thesaurus. Volume 1: Hierarchical listing

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    There are 16,713 postable terms and 3,716 nonpostable terms approved for use in the NASA scientific and technical information system in the Hierarchical Listing of the NASA Thesaurus. The generic structure is presented for many terms. The broader term and narrower term relationships are shown in an indented fashion that illustrates the generic structure better than the more widely used BT and NT listings. Related terms are generously applied, thus enhancing the usefulness of the Hierarchical Listing. Greater access to the Hierarchical Listing may be achieved with the collateral use of Volume 2 - Access Vocabulary
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