Brain-Inspired Computing

This open access book constitutes revised selected papers from the 4th International Workshop on Brain-Inspired Computing, BrainComp 2019, held in Cetraro, Italy, in July 2019. The 11 papers presented in this volume were carefully reviewed and selected for inclusion in this book. They deal with research on brain atlasing, multi-scale models and simulation, HPC and data infra-structures for neuroscience as well as artificial and natural neural architectures

Unraveling the multiscale structural organization and connectivity of the human brain: the role of diffusion MRI

The structural architecture and the anatomical connectivity of the human brain show different organizational principles at distinct spatial scales. Histological staining and light microscopy techniques have been widely used in classical neuroanatomical studies to unravel brain organization. Using such techniques is a laborious task performed on 2-dimensional histological sections by skilled anatomists possibly aided by semi-automated algorithms. With the recent advent of modern magnetic resonance imaging (MRI) contrast mechanisms, cortical layers and columns can now be reliably identified and their structural properties quantified post-mortem. These developments are allowing the investigation of neuroanatomical features of the brain at a spatial resolution that could be interfaced with that of histology. Diffusion MRI and tractography techniques, in particular, have been used to probe the architecture of both white and gray matter in three dimensions. Combined with mathematical network analysis, these techniques are increasingly influential in the investigation of the macro-, meso-, and microscopic organization of brain connectivity and anatomy, both in vivo and ex vivo. Diffusion MRI-based techniques in combination with histology approaches can therefore support the endeavor of creating multimodal atlases that take into account the different spatial scales or levels on which the brain is organized. The aim of this review is to illustrate and discuss the structural architecture and the anatomical connectivity of the human brain at different spatial scales and how recently developed diffusion MRI techniques can help investigate these

Whole-brain cortical parcellation: A hierarchical method based on dMRI tractography

In den modernen Neurowissenschaften ist allgemein anerkannt, dass die Gehirnfunktionen auf dem Zusammenwirken von verschiedenen Regionen in Netzwerken beruhen und die strukturelle Konnektivität daher großer Bedeutung ist. Daher kann die Abgrenzung funktioneller Hirnbereiche auf der Grundlage der Diffusions-Magnet-Resonanz-Tomographie (dMRT) und der Traktografie zu wertvollen Hirnkarten führen.Existierende Verfahren versuchen eine fest vorgegebene Anzahl von Regionen zu finden und/oder sind auf kleine Bereiche der grauen Substanz beschränkt. Im Allgemeinen ist es jedoch unwahrscheinlich, dass eine einzelne Parzellierung des Kortex, eine ausreichende Darstellung der funktio- anatomischen Organisation des Gehirns erlaubt. In dieser Arbeit schlagen wir eine hierarchische Clusteranalyse vor um diese Einschränkungen zu überwinden und das gesamte Gehirn zu parzellieren. Wir zeigen, dass dieses Verfahren die Eigenschaften der zugrundeliegenden Struktur auf allen Granularitätstufen des hierarchischen Baums (Dendrogramm) kodieren kann. Weiterhin entwickeln wir eine optimale Verarbeitungspipeline zur Erstellung dieses Baums, die dessen Komplexität mit minimalem Informationsverlust reduziert. Wir zeigen wie diese Datenstrukturen verwendet werden können um die Ähnlichkeitstruktur von verschiedenen Probanden oder Messungen zu vergleichen und wie man daraus verschiedene Parzellierungen des Gehirns erhalten kann.Unser neuer Ansatz liefert eine ausführlichere Analyse der anatomischen Strukturen und bietet eine Methode zur Parzellierung des ganzen Gehirns.In modern neuroscience there is general agreement that brain function relies on networks and that connectivity is therefore of paramount importance for brain function. Accordingly, the delineation of functional brain areas on the basis of diffusion magnetic resonance imaging (dMRI) and tractography may lead to highly relevant brain maps.Existing methods typically aim to find a predefined number of areas and/or are limited to small regions of grey matter. However, it is in general not likely that a single parcellation dividing the brain into a finite number of areas is an adequate representation of the function-anatomical organization of the brain. In this work, we propose hierarchical clustering as a solution to overcome these limitations and achieve whole-brain parcellation. We demonstrate that this method encodes the information of the underlying structure at all granularity levels in a hierarchical tree or dendrogram. We develop an optimal tree building and processing pipeline that reduces the complexity of the tree with minimal information loss. We show how these trees can be used to compare the similarity structure of different subjects or recordings and how to extract parcellations from them.Our novel approach yields a more exhaustive representation of the real underlying structure and successfully tackles the challenge of whole-brain parcellation

Principles of organisation within the pathways in the brainstem and thalamus

There are few detailed studies on the pathways through the human brainstem and even fewer on those through the pons. This thesis aims to address this lack of fine detail, and used ultra-high-field magnetic resonance imaging (MRI) of human and macaque brains to identify and characterise fibre tracts connecting cortical and spinal areas as they traverse through brainstem and thalamic structures. The material in this thesis is based on a unique dataset of ultra-high-field (7 Tesla – Duke and 11, 7 Tesla – Johns Hopkins) MRI scans on postmortem specimens, on which deterministic tractography has been applied based on high-angular-resolution diffusion imaging (HARDI) and subsequently higher order tensor glyph models. The first results section of the thesis (Chapter 3) maps the descending fibre bundles associated with movement. From the motor cortical areas, the fibres of the internal capsule are traced through the crus cerebri, basilar pons and pyramids in three dimensions to reveal their organisation into functional and topographic subdivisions. While human cortico-pontine, -bulbar and -spinal tracts were traditionally considered to be dispersed, or a “melange”, I show here a much more discrete and defined organisation of these descending fibre bundles. Nine descending fibre bundles are identified and their anatomical location and terminations are described. A hitherto unknown pathway at the midline of the pons has been discovered and named herein as the Stria Pontis which connects the neocortex to the pontine tegmentum. Ten transverse fibre bundles connecting the pontine nuclei to the cerebellum are also identified. The second results section (Chapter 4) analyses the sensory pathways; the dorsal column - medial lemniscus pathway, the spinothalamic tract, the spinal trigeminal tract and the trigeminothalamic tracts. The third results section (Chapter 5) analyses the dentato-rubro-thalamic tract. The mapping identifies the superior cerebellar peduncle, the patterning of the fibres within the superior cerebellar decussation, the patterning of the fibres within the red nucleus and finally the projection of the dentato-rubro-thalamic tract from the red nucleus to the ventral lateral nucleus of the thalamus. Finally, I characterised 117 already known anatomical parts, areas and structures of the brainstem and thalamus in 3D

Analyse et reconstruction de faisceaux de la matière blanche

L'imagerie par résonance magnétique de diffusion (IRMd) est une modalité d'acquisition permettant de sonder les tissus biologiques et d'en extraire une variété d'informations sur le mouvement microscopique des molécules d'eau. Plus spécifiquement à l'imagerie médicale, l'IRMd permet l'investigation des structures fibreuses de nombreux organes et facilite la compréhension des processus cognitifs ou au diagnostic. Dans le domaine des neurosciences, l'IRMd est cruciale à l'exploration de la connectivité structurelle de la matière blanche. Cette thèse s'intéresse plus particulièrement à la reconstruction de faisceaux de la matière blanche ainsi qu'à leur analyse. Toute la complexité du traitement des données commençant au scanneur jusqu'à la création d'un tractogramme est extrêmement importante. Par contre, l'application spécifique de reconstruction des faisceaux anatomiques plausibles est ultimement le véritable défi de l'IRMd. L'optimisation des paramètres de la tractographie, le processus de segmentation manuelle ou automatique ainsi que l'interprétation des résultats liée à ces faisceaux sont toutes des étapes du processus avec leurs lots de difficultés

Tracing of Nerve Fibers Through Brain Regions of Fiber Crossings in Reconstructed 3D-PLI Volumes

Three-dimensional (3D) polarized light imaging (PLI) is able to reveal nerve fibers in the human brain at microscopic resolution. While most nerve fiber structures can be accurately visualized with 3D-PLI, the currently used physical model (based on Jones Calculus) is not well suited to distinguish steep fibers from specific fiber crossings. Hence, streamline tractography algorithms tracing fiber pathways get easily misdirected in such brain regions. For the presented study, we implemented and applied two methods to bridge areas of fiber crossings: (i) extrapolation of fiber points with cubic splines and (ii) following the most frequently occurring orientations in a defined neighborhood based on orientation distribution functions gained from 3D-PLI measurements (pliODFs). Applied to fiber crossings within a human hemisphere, reconstructed from 3D-PLI measurements at 64 microns in-pane resolution, both methods were demonstrated to sustain their initial tract direction throughout the crossing region. In comparison, the ODF-method offered a more reliable bridging of the crossings with less gaps

Activation of the pro-resolving receptor Fpr2 attenuates inflammatory microglial activation

Poster number: P-T099 Theme: Neurodegenerative disorders & ageing Activation of the pro-resolving receptor Fpr2 reverses inflammatory microglial activation Authors: Edward S Wickstead - Life Science & Technology University of Westminster/Queen Mary University of London Inflammation is a major contributor to many neurodegenerative disease (Heneka et al. 2015). Microglia, as the resident immune cells of the brain and spinal cord, provide the first line of immunological defence, but can become deleterious when chronically activated, triggering extensive neuronal damage (Cunningham, 2013). Dampening or even reversing this activation may provide neuronal protection against chronic inflammatory damage. The aim of this study was to determine whether lipopolysaccharide (LPS)-induced inflammation could be abrogated through activation of the receptor Fpr2, known to play an important role in peripheral inflammatory resolution. Immortalised murine microglia (BV2 cell line) were stimulated with LPS (50ng/ml) for 1 hour prior to the treatment with one of two Fpr2 ligands, either Cpd43 or Quin-C1 (both 100nM), and production of nitric oxide (NO), tumour necrosis factor alpha (TNFα) and interleukin-10 (IL-10) were monitored after 24h and 48h. Treatment with either Fpr2 ligand significantly suppressed LPS-induced production of NO or TNFα after both 24h and 48h exposure, moreover Fpr2 ligand treatment significantly enhanced production of IL-10 48h post-LPS treatment. As we have previously shown Fpr2 to be coupled to a number of intracellular signaling pathways (Cooray et al. 2013), we investigated potential signaling responses. Western blot analysis revealed no activation of ERK1/2, but identified a rapid and potent activation of p38 MAP kinase in BV2 microglia following stimulation with Fpr2 ligands. Together, these data indicate the possibility of exploiting immunomodulatory strategies for the treatment of neurological diseases, and highlight in particular the important potential of resolution mechanisms as novel therapeutic targets in neuroinflammation. References Cooray SN et al. (2013). Proc Natl Acad Sci U S A 110: 18232-7. Cunningham C (2013). Glia 61: 71-90. Heneka MT et al. (2015). Lancet Neurol 14: 388-40

Annual Report of the Board of Regents of the Smithsonian Institution, showing the operations, expenditures, and condition of the institution for the year 1868.

Annual Report of the Smithsonian Institution. 13 Feb. HED 83, 40-3, v12, 473p. [1380] Research and publications related to the American Indian; systems of relationship among Indians; etc