Spectral mapping of brain functional connectivity from diffusion imaging.

Understanding the relationship between the dynamics of neural processes and the anatomical substrate of the brain is a central question in neuroscience. On the one hand, modern neuroimaging technologies, such as diffusion tensor imaging, can be used to construct structural graphs representing the architecture of white matter streamlines linking cortical and subcortical structures. On the other hand, temporal patterns of neural activity can be used to construct functional graphs representing temporal correlations between brain regions. Although some studies provide evidence that whole-brain functional connectivity is shaped by the underlying anatomy, the observed relationship between function and structure is weak, and the rules by which anatomy constrains brain dynamics remain elusive. In this article, we introduce a methodology to map the functional connectivity of a subject at rest from his or her structural graph. Using our methodology, we are able to systematically account for the role of structural walks in the formation of functional correlations. Furthermore, in our empirical evaluations, we observe that the eigenmodes of the mapped functional connectivity are associated with activity patterns associated with different cognitive systems

The left superior temporal gyrus is a shared substrate for auditory short-term memory and speech comprehension: evidence from 210 patients with stroke

Competing theories of short-term memory function make specific predictions about the functional anatomy of auditory short-term memory and its role in language comprehension. We analysed high-resolution structural magnetic resonance images from 210 stroke patients and employed a novel voxel based analysis to test the relationship between auditory short-term memory and speech comprehension. Using digit span as an index of auditory short-term memory capacity we found that the structural integrity of a posterior region of the superior temporal gyrus and sulcus predicted auditory short-term memory capacity, even when performance on a range of other measures was factored out. We show that the integrity of this region also predicts the ability to comprehend spoken sentences. Our results therefore support cognitive models that posit a shared substrate between auditory short-term memory capacity and speech comprehension ability. The method applied here will be particularly useful for modelling structure–function relationships within other complex cognitive domains

Editorial: Organization of the White Matter Anatomy in the Human Brain

International audienceEditorial on the Research Topic Organization of the White Matter Anatomy in the Human Brain Between nineteenth and twentieth centuries, neurosciences experienced the first sharing of experiences and competences between the world of brain anatomy and clinics. The improvements in the knowledge of human white matter (WM) anatomy provided the natural background to the structural definition of a wide spectrum of clinical syndromes. This "disconnection" experience was the first field of strict integration between the WM anatomical and clinical skills, and constituted the hard core for the development of the modern neurosciences over the last century (Catani and ffytche, 2005). While the second half of twentieth century has seen the neurophysiology taking a front role in the definition of the physiological and physio-pathological processing of brain circuitries, the last decade has definitively brought neuroimaging into the world of neuroscience. The functional magnetic resonance imaging (fMRI) and diffusion-weighted MRI (DWI) tractography have successively opened a new era for a better understanding of functional and structural anatomy of the human brain (Le Bihan and Johansen-Berg, 2012; Smith et al., 2013). In particular, DWI-based tractography was the first tool allowing the exploration of human WM in vivo with an unprecedented level of details, and it shed a new light in the knowledge of the brain anatomy that became, finally, more accessible (Jeurissen et al., 2019). Beyond the technical aspects related to the continuous necessary improvement of this approach (Maier-Hein et al., 2017), tractography produced a conceptual revolution leading that the wiring diagram of brain connections regained a center scene of neuroscience research. Such a revolution was not only in research but also in the clinical and neurosurgical domains and opened the "connectome" era (Sporns, 2013). The fields of neuroanatomy, neuroimaging, neurophysiology and clinical researches are currently closer as never before. In fact, two decades of exploration of brain structure and functional processing with an unprecedented level of sensitivity opened new challenges. Among others, the research for a ground truth in structural anatomy is definitely the most impressive, especially considering the basic and conceptual consequences of that in assessing a reliable knowledge of brain processing, clinics and plasticity. This is what the vast majority of the articles in this Research Topic highlight by describing association WM pathways (Bao et al.; David et al.; Panesar et al.), cortico-striatal Cacciola et al. and cortico-thalamic (Maffei et al.; Roddy et al.; Sun et al.) projection pathways

SNARE proteins as molecular masters of interneuronal communication

In the beginning of the 20th century the groundbreaking work\ud of Ramon y Cajal firmly established the neuron doctrine, according to which neurons are the basic structural and functional units of the nervous system. Von Weldeyer coined the term “neuron” in 1891, but the huge leap forward in\ud neuroscience was due to Cajal’s meticulous microscopic observations of brain sections stained with an improved version of Golgi’s la reazione nera (black reaction). The latter improvement of Golgi’s technique made it possible to visualize the arborizations of single neurons that were “colored brownish black even to their finest branchlets, standing out with unsurpassable clarity upon a transparent yellow background. All was sharp as a sketch with Chinese ink”. The high quality of both the visualization of individual nerve cells and the work performed on studying the anatomy of the central nervous system lead Ramon y Cajal to the conclusion that axons output the nervous impulses to the dendrites or the soma of other target neurons

Functional Anatomy: A Taxonomic Proposal

It is argued that medical science requires a classificatory system that (a) puts functions in the taxonomic center and (b) does justice ontologically to the difference between the processes which are the realizations of functions and the objects which are their bearers. We propose formulae for constructing such a system and describe some of its benefits. The arguments are general enough to be of interest to all the life sciences

Imaging Informatics and the Human Brain Project: the Role of Structure, Review

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The Foundational Model of Anatomy Ontology

Anatomy is the structure of biological organisms. The term also denotes the scientific discipline devoted to the study of anatomical entities and the structural and developmental relations that obtain among these entities during the lifespan of an organism. Anatomical entities are the independent continuants of biomedical reality on which physiological and disease processes depend, and which, in response to etiological agents, can transform themselves into pathological entities. For these reasons, hard copy and in silico information resources in virtually all fields of biology and medicine, as a rule, make extensive reference to anatomical entities. Because of the lack of a generalizable, computable representation of anatomy, developers of computable terminologies and ontologies in clinical medicine and biomedical research represented anatomy from their own more or less divergent viewpoints. The resulting heterogeneity presents a formidable impediment to correlating human anatomy not only across computational resources but also with the anatomy of model organisms used in biomedical experimentation. The Foundational Model of Anatomy (FMA) is being developed to fill the need for a generalizable anatomy ontology, which can be used and adapted by any computer-based application that requires anatomical information. Moreover it is evolving into a standard reference for divergent views of anatomy and a template for representing the anatomy of animals. A distinction is made between the FMA ontology as a theory of anatomy and the implementation of this theory as the FMA artifact. In either sense of the term, the FMA is a spatial-structural ontology of the entities and relations which together form the phenotypic structure of the human organism at all biologically salient levels of granularity. Making use of explicit ontological principles and sound methods, it is designed to be understandable by human beings and navigable by computers. The FMA’s ontological structure provides for machine-based inference, enabling powerful computational tools of the future to reason with biomedical data

Function-based Intersubject Alignment of Human Cortical Anatomy

Making conclusions about the functional neuroanatomical organization of the human brain requires methods for relating the functional anatomy of an individual's brain to population variability. We have developed a method for aligning the functional neuroanatomy of individual brains based on the patterns of neural activity that are elicited by viewing a movie. Instead of basing alignment on functionally defined areas, whose location is defined as the center of mass or the local maximum response, the alignment is based on patterns of response as they are distributed spatially both within and across cortical areas. The method is implemented in the two-dimensional manifold of an inflated, spherical cortical surface. The method, although developed using movie data, generalizes successfully to data obtained with another cognitive activation paradigm—viewing static images of objects and faces—and improves group statistics in that experiment as measured by a standard general linear model (GLM) analysis