scholarly journals Neuron density fundamentally relates to architecture and connectivity of the primate cerebral cortex

2017 ◽  
Author(s):  
Sarah F. Beul ◽  
Claus C. Hilgetag
Keyword(s):  
Cerebral Cortex ◽  
Brain Connectivity ◽  
Dendritic Tree ◽  
Cortical Connectivity ◽  
Cortical Organization ◽  
Cortical Areas ◽  
Neuron Density ◽  
Soma Size ◽  
And Function ◽  
Primate Cerebral Cortex

AbstractStudies of structural brain connectivity have revealed many intriguing features of complex cortical networks. To advance integrative theories of cortical organization, an understanding is required of how connectivity interrelates with other aspects of brain structure. Recent studies have suggested that interareal connectivity may be related to a variety of macroscopic as well as microscopic architectonic features of cortical areas. However, it is unclear how these features are inter-dependent and which of them most strongly and fundamentally relate to structural corticocortical connectivity. Here, we systematically investigated the relation of a range of microscopic and macroscopic architectonic features of cortical organization, namely layer III pyramidal cell soma size, dendritic synapse count, dendritic synapse density and dendritic tree size as well as area neuron density, to multiple properties of cortical connectivity, using a comprehensive, up-to-date structural connectome of the primate brain. Importantly, relationships were investigated by multi-variate analyses to account for the interrelations of features. Of all considered factors, the classical architectonic parameter of neuron density most strongly and consistently related to essential features of cortical connectivity (existence and laminar patterns of projections, area degree), and in conjoint analyses largely abolished effects of cellular morphological features. These results reveal neuron density as a central architectonic indicator of the primate cerebral cortex that is closely related to essential aspects of brain connectivity and is also highly indicative of further features of the architectonic organization of cortical areas such as the considered cellular morphological measures. Our findings integrate several aspects of cortical micro-and macroscopic organization, with implications for cortical development and function.

Connectivity and cortical architecture

e-Neuroforum ◽  
2016 ◽  
Vol 22 (3) ◽  
Author(s):  
Claus C. Hilgetag ◽  
Katrin Amunts
Keyword(s):  
Cerebral Cortex ◽  
Regional Distribution ◽  
Brain Regions ◽  
Cortical Connectivity ◽  
Cortical Areas ◽  
Histological Data ◽  
Classic Approach ◽  
Differential Density ◽  
Analytical Approaches ◽  
Cortical Architecture

AbstractBrain regions of the cerebral cortex differ in their cytoarchitecture as well as in the intrinsic connectivity within an area and the organization of macroscopic connections between different cortical areas. Nonetheless, it is not clear which rules underlie the relationship of cellular and fiber architecture, and how the characteristic cortical microand macro-connectivity are related to each other. In order to identify principles of cortical connectivity, we systematically investigate various parameters of cortical architecture and their relation to the organization of anatomical connections among cortical areas. Characteristic parameters of cortical architecture include the differential density and distribution of neurons and neuron types across the layers of cortical areas, as well as the regional distribution of different receptors of neurotransmitter systems. The cytoarchitectonic characterization of the brain is a classic approach of neuroanatomy, which recently has been supplemented by new techniques for labeling specific neural components as well as novel optical and analytical approaches. However, the systematic quantitative acquisition of architectonic and morphological parameters of the human brain has only just begun. It is a fundamental challenge to gather and quantify the extremely extensive and detailed histological data (“big data”) by novel image processing techniques. This challenge is taken up in the BigBrain project. Extensive anatomical data already exist for a number of animal models, for example, the brains of nonhuman primates, the cat or the mouse. However, for each single parameter it has to be demonstrated how far these data can be generalized across species. Previous analyses support the notion that the regionally specific cytoarchitecture of the cerebral cortex is closely linked to the existence and the laminar projection patterns of corticocortical connections. These results imply systematic relationships between the patterns of macroscopic connections among cortical areas and the regionally specific intrinsic circuitry within cortical areas. Such relations are the basis of generic models of multiscale cortical connectivity, which reflect essential anatomical and functional properties of mammalian cortical organization.

scholarly journals Cortical and thalamic connectivity of occipital visual cortical areas 17, 18, 19 and 21 of the domestic ferret (Mustela putorius furo).

2018 ◽  
Author(s):  
Leigh-Anne Dell ◽  
Giorgio M Innocenti ◽  
Claus C Hilgetag ◽  
Paul R Manger
Keyword(s):  
Brain Connectivity ◽  
Dorsal Stream ◽  
Mustela Putorius ◽  
Cortical Connectivity ◽  
Ipsilateral Hemisphere ◽  
Dorsal Thalamus ◽  
Visual Thalamus ◽  
Cortical Areas ◽  
Visual Areas ◽  
Visual Cortical

The present study describes the ipsilateral and contralateral cortico-cortical and cortico-thalamic connectivity of the occipital visual areas 17,18, 19 and 21 in the ferret using standard anatomical tract-tracing methods. In line with previous studies of mammalian visual cortex connectivity, substantially more anterograde and retrograde label was present in the hemisphere ipsilateral to the injection site compared to the contralateral hemisphere. Ipsilateral reciprocal connectivity was the strongest within the occipital visual areas, while weaker connectivity strength was observed in the temporal, suprasylvian and parietal visual areas. Callosal connectivity tended to be strongest in the homotopic cortical areas, and revealed a similar areal distribution to that observed in the ipsilateral hemisphere, although often less widespread across cortical areas. Ipsilateral reciprocal connectivity was observed throughout the visual nuclei of the dorsal thalamus, with no contralateral connections to the visual thalamus being observed. The current study, along with previous studies of connectivity in the cat, identified the posteromedial lateral suprasylvian visual area (PMLS) as a distinct network hub external to the occipital visual areas in carnivores, implicating PMLS as a potential gateway to the parietal cortex for dorsal stream processing. These data will also contribute to the Ferretome (www.ferretome.org), a macro connectome database of the ferret brain, providing essential data for connectomics analyses and cross-species analyses of connectomes and brain connectivity matrices, as well as providing data relevant to additional studies of cortical connectivity across mammals and the evolution of cortical connectivity variation.

scholarly journals The Cortical Spectrum: a robust structural continuum in primate cerebral cortex revealed by histological staining and magnetic resonance imaging

2021 ◽  
Author(s):  
Yohan J. John ◽  
Basilis Zikopoulos ◽  
Miguel Ángel García-Cabezas ◽  
Helen Barbas
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cerebral Cortex ◽  
Magnetic Resonance ◽  
Coarse Grained ◽  
Specific Method ◽  
Resonance Imaging ◽  
Cortical Function ◽  
Cortical Areas ◽  
Primate Cerebral Cortex ◽  
Histological Staining

AbstractHigh-level characterizations of the primate cerebral cortex sit between two extremes: on one end the cortical mantle is seen as a mosaic of structurally and functionally unique areas, and on the other it is seen as a uniform six-layered structure in which functional differences are defined solely by extrinsic connections. Neither of these extremes captures the crucial neuroanatomical finding: that the cortex exhibits systematic gradations in architectonic structure. These gradations have been shown to predict cortico-cortical connectivity, which in turn suggests powerful ways to ground connectomics in anatomical structure, and by extension cortical function. A challenge to more widespread use of this concept is the labor-intensive and invasive nature of histological staining, which is the primary means of recognizing anatomical gradations. Here we show that a novel computational analysis technique can be used to derive a coarse-grained picture of cortical variation. For each of 78 cortical areas spanning the entire cortical mantle of the rhesus macaque, we created a high dimensional set of anatomical features derived from captured images of cortical tissue stained for myelin and SMI-32. The method involved semi-automated de-noising of images, and enabled comparison of brain areas without hand-labeling of features such as layer boundaries. We applied nonmetric multidimensional scaling (NMDS) to the dataset to visualize similarity among cortical areas. This analysis shows a systematic variation between weakly laminated (limbic) cortices and sharply laminated (eulaminate) cortices. We call this smooth continuum the ‘cortical spectrum’. We also show that this spectrum is visible within subsystems of the cortex: the occipital, parietal, temporal, motor, prefrontal, and insular cortices. We compared the NMDS-derived spectrum with a spectrum produced using T1- and T2-weighted magnetic resonance imaging (MRI) data derived from macaque, and found close agreement of the two coarse-graining methods. This evidence suggests that T1/T2 data, routinely obtained in human MRI studies, can be used as an effective proxy for data derived from high-resolution histological methods. More generally, this approach shows that the cortical spectrum is robust to the specific method used to compare cortical areas, and is therefore a powerful tool to understand the principles of organization of the primate cortex.

Neocortical Microcircuits

2017 ◽  
pp. 3-22
Author(s):  
Javier DeFelipe ◽  
Bernardo Rudy
Keyword(s):  
Cerebral Cortex ◽  
Cortical Circuits ◽  
Input Output ◽  
Cortical Organization ◽  
Cortical Areas ◽  
History Of ◽  
Detailed Circuit ◽  
General Aspects ◽  
Cellular Components

Throughout the history of neuroscience, scientists have been trying to generate simplified diagrams of the cerebral cortex that represent the main cellular components and their possible connections. New methods of studying the physiology and connectivity of cortical circuits have been combined with computational neuroscience and computer simulations in order to make it possible to learn more about the role of each element in the input-output circuit. The ultimate goal is to try to understand the functional implications of cortical organization using more detailed circuit diagrams than previously possible. This is a particularly difficult task when dealing with the neocortex, not only because of its complexity, but also because of the variations observed between different cortical areas and across species. This chapter will deal with general aspects of the main neuronal components of the neocortex and the way in which these components are interconnected in a general, basic microcircuit.

Normal ageing and the brain

1998 ◽  
Vol 15 (1) ◽  
pp. 26-28
Author(s):  
CS Breathnach
Keyword(s):  
Cerebral Cortex ◽  
Imaging Techniques ◽  
Structure And Function ◽  
Ageing Population ◽  
Cell Shrinkage ◽  
Ageing Processes ◽  
Normal Ageing ◽  
And Function ◽  
Ageing Brain ◽  
The Brain

AbstractInterest in the psychiatric aspects of old age predated the institution of geriatrics as a clinical discipline, but the systematic study of the ageing brain only began in the second half of this century when an ageing population presented a global numerical challenge to society. In the senescent cerebral cortex, though the number of neurons is not reduced, cell shrinkage results in synaptic impoverishment with consequent cognitive impairment. Recent advances in imaging techniques, combined with burgeoning knowledge of neurobiological structure and function, have increased our understanding of the ageing processes in the human brain and permit an optimistic approach in the application of the newer insights into neuropsychology and geriatric psychiatry.

scholarly journals The Expression and Distributions of ANP32A in the Developing Brain

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Shanshan Wang ◽  
Yunliang Wang ◽  
Qingshan Lu ◽  
Xinshan Liu ◽  
Fuyu Wang ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Fetal Brain ◽  
Tissue Expression ◽  
Developing Brain ◽  
Adult Brain ◽  
Mammalian Brain ◽  
Dependent Manner ◽  
Growing Up ◽  
Embryonic Mouse ◽  
And Function

Acidic (leucine-rich) nuclear phosphoprotein 32 family, member A (ANP32A), has multiple functions involved in neuritogenesis, transcriptional regulation, and apoptosis. However, whether ANP32A has an effect on the mammalian developing brain is still in question. In this study, it was shown that brain was the organ that expressed the most abundant ANP32A by human multiple tissue expression (MTE) array. The distribution of ANP32A in the different adult brain areas was diverse dramatically, with high expression in cerebellum, temporal lobe, and cerebral cortex and with low expression in pons, medulla oblongata, and spinal cord. The expression of ANP32A was higher in the adult brain than in the fetal brain of not only humans but also mice in a time-dependent manner. ANP32A signals were dispersed accordantly in embryonic mouse brain. However, ANP32A was abundant in the granular layer of the cerebellum and the cerebral cortex when the mice were growing up, as well as in the Purkinje cells of the cerebellum. The variation of expression levels and distribution of ANP32A in the developing brain would imply that ANP32A may play an important role in mammalian brain development, especially in the differentiation and function of neurons in the cerebellum and the cerebral cortex.

scholarly journals The lizard cerebral cortex as a model to study neuronal regeneration

2002 ◽  
Vol 74 (1) ◽  
pp. 85-104 ◽  
Author(s):  
CARLOS LOPEZ-GARCIA ◽  
ASUNCION MOLOWNY ◽  
JUAN NACHER ◽  
XAVIER PONSODA ◽  
FRANCISCO SANCHO-BIELSA ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Neuronal Death ◽  
Cell Layer ◽  
Neuronal Regeneration ◽  
Postnatal Neurogenesis ◽  
Continuous Growth ◽  
Cortical Areas ◽  
Medial Cortex ◽  
Chemical Lesion ◽  
Neuroblast Proliferation

The medial cerebral cortex of lizards, an area homologous to the hippocampal fascia dentata, shows delayed postnatal neurogenesis, i.e., cells in the medial cortex ependyma proliferate and give rise to immature neurons, which migrate to the cell layer. There, recruited neurons differentiate and give rise to zinc containing axons directed to the rest of cortical areas, thus resulting in a continuous growth of the medial cortex and its zinc-enriched axonal projection. This happens along the lizard life span, even in adult lizards, thus allowing one of their most important characteristics: neuronal regeneration. Experiments in our laboratory have shown that chemical lesion of the medial cortex (affecting up to 95% of its neurons) results in a cascade of events: first, massive neuronal death and axonal-dendritic retraction and, secondly, triggered ependymal-neuroblast proliferation and subsequent neo-histogenesis and regeneration of an almost new medial cortex, indistinguishable from a normal undamaged one. This is the only case to our knowledge of the regeneration of an amniote central nervous centre by new neuron production and neo-histogenesis. Thus the lizard cerebral cortex is a good model to study neuronal regeneration and the complex factors that regulate its neurogenetic, migratory and neo-synaptogenetic events.

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