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 Synaptophysin gene expression in schizophrenia

2000 ◽  
Vol 176 (3) ◽  
pp. 236-242 ◽  
Author(s):  
Sharon L. Eastwood ◽  
Nigel J. Cairns ◽  
Paul J. Harrison
Keyword(s):  
Gene Expression ◽  
Cerebral Cortex ◽  
Prefrontal Cortex ◽  
Messenger Rna ◽  
Regional Distribution ◽  
Anterior Cingulate ◽  
Cortical Areas ◽  
Dorsolateral Prefrontal ◽  
Synaptic Pathology

BackgroundDecreased expression of proteins such as synaptophysin in the hippocampus and prefrontal cortex in schizophrenia is suggestive of synaptic pathology. However, the overall profile of changes is unclear.AimsTo investigate synaptophysin gene expression in the cerebral cortex in schizophrenia.MethodThe dorsolateral prefrontal (Brodmann area [BA] 9/46), anterior cingulate (BA 24), superior temporal (BA 22) and occipital (BA 17) cortex were studied in two series of brains, totalling 19 cases and 19 controls. Synaptophysin was measured by immunoautoradiography and immunoblotting. Synaptophysin messenger RNA (m RNA) was measured using in situ hybridisation.ResultsSynaptophysin was unchanged in schizophrenia, except for a reduction in BA 17 of one brain series. Synaptophysin mRNA was decreased in BA 17, and in BA 22 in the women with schizophrenia. No alterations were seen in BA 9/46.ConclusionsSynaptophysin expression is decreased in some cortical areas in schizophrenia. The alterations affect the mRNA more than the protein, and have an unexpected regional distribution. The characteristics of the implied synaptic pathology remain to be determined.

scholarly journals Patterning and Plasticity of the Cerebral Cortex

Science ◽  
2005 ◽  
Vol 310 (5749) ◽  
pp. 805-810 ◽  
Author(s):  
Mriganka Sur ◽  
John L. R. Rubenstein
Keyword(s):  
Cerebral Cortex ◽  
Human Brain ◽  
Brain Regions ◽  
Cortical Areas ◽  
Processing Networks

The cerebral cortex of the human brain is a sheet of about 10 billion neurons divided into discrete subdivisions or areas that process particular aspects of sensation, movement, and cognition. Recent evidence has begun to transform our understanding of how cortical areas form, make specific connections with other brain regions, develop unique processing networks, and adapt to changes in inputs.

Synaptosomal T3 binding sites in rat brain: their localization on synaptic membrane and regional distribution

1983 ◽  
Vol 104 (2) ◽  
pp. 134-138 ◽  
Author(s):  
Yasuo Mashio ◽  
Mitsuo Inada ◽  
Kiyoshi Tanaka ◽  
Hitoshi Ishii ◽  
Koichi Naito ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Rat Brain ◽  
Binding Sites ◽  
Binding Capacity ◽  
Regional Distribution ◽  
Brain Regions ◽  
Synaptic Membranes ◽  
Synaptic Membrane ◽  
Scatchard Analysis ◽  
Affinity Binding

Abstract. Previous studies have shown the existence of specific high affinity T3 binding sites in rat cerebrocortical synaptosomes. In this study, to define the localization of the binding sites, T3 binding to disrupted synaptic membrane fractions was compared with the binding to intact synaptosomes obtained from the rat cerebral cortex. Scatchard analysis revealed two orders of T3 binding sites with almost identical apparent dissociation constant (Kd) in synaptosomes and synaptic membrane fractions. However, the maximal binding capacity (MBC) of the higher affinity binding sites for synaptic membrane fractions was significantly greater than that for intact synaptosomes (4.2 ± 0.2 vs 3.0 ± 0.3 pg T3/mg protein). Regional distribution of the synaptosomal T3 binding sites in various areas of the rat brain was also studied. The Kd values were not significantly different in discrete brain regions. On the other hand, the MBCs of the higher affinity binding sites were greater in the cerebral cortex and hypothalamus (72.8 ± 1.4 and 64.8 ± 9.5 pg T3/g tissue) than in the cerebellum (22.1 ± 1.6 pg T3/g tissue). Similar difference was also observed in the lower affinity sites. These results indicate that the specific T3 binding sites in brain synaptosomes are localized mainly on synaptic membranes and that the MBC is different in discrete brain regions.

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.

Engaging regularly with fiction influences connectivity in cortical areas for language and mentalizing

2017 ◽  
Author(s):  
Roel M. Willems ◽  
Franziska Hartung
Keyword(s):  
Functional Connectivity ◽  
Time Course ◽  
Language Skills ◽  
Brain Regions ◽  
Brain Areas ◽  
Daily Lives ◽  
Cortical Areas ◽  
Social Abilities ◽  
Behavioral Evidence ◽  
Amount Of Reading

Behavioral evidence suggests that engaging with fiction is positively correlated with social abilities. The rationale behind this link is that engaging with fictional narratives offers a ‘training modus’ for mentalizing and empathizing. We investigated the influence of the amount of reading that participants report doing in their daily lives, on connections between brain areas while they listened to literary narratives. Participants (N=57) listened to two literary narratives while brain activation was measured with fMRI. We computed time-course correlations between brain regions, and compared the correlation values from listening to narratives to listening to reversed speech. The between-region correlations were then related to the amount of fiction that participants read in their daily lives. Our results show that amount of fiction reading is related to functional connectivity in areas known to be involved in language and mentalizing. This suggests that reading fiction influences social cognition as well as language skills.

scholarly journals Cortical neurons exhibit diverse myelination patterns that scale between mouse brain regions and regenerate after demyelination

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cody L. Call ◽  
Dwight E. Bergles
Keyword(s):  
Cortical Neurons ◽  
Regional Differences ◽  
Brain Regions ◽  
Axon Diameter ◽  
Neuronal Identity ◽  
Cortical Areas ◽  
Myelin Sheaths ◽  
Parvalbumin Interneurons ◽  
Selection Of

ABSTRACTAxons in the cerebral cortex show a broad range of myelin coverage. Oligodendrocytes establish this pattern by selecting a cohort of axons for myelination; however, the distribution of myelin on distinct neurons and extent of internode replacement after demyelination remain to be defined. Here we show that myelination patterns of seven distinct neuron subtypes in somatosensory cortex are influenced by both axon diameter and neuronal identity. Preference for myelination of parvalbumin interneurons was preserved between cortical areas with varying myelin density, suggesting that regional differences in myelin abundance arises through local control of oligodendrogenesis. By imaging loss and regeneration of myelin sheaths in vivo we show that myelin distribution on individual axons was altered but overall myelin content on distinct neuron subtypes was restored. Our findings suggest that local changes in myelination are tolerated, allowing regenerated oligodendrocytes to restore myelin content on distinct neurons through opportunistic selection of axons.

scholarly journals Diversity of neurovascular coupling dynamics along vascular arbors in layer II/III somatosensory cortex

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ravi L. Rungta ◽  
Marc Zuend ◽  
Ali-Kemal Aydin ◽  
Éric Martineau ◽  
Davide Boido ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Somatosensory Cortex ◽  
Cerebral Blood Volume ◽  
Transfer Functions ◽  
Neurovascular Coupling ◽  
Sensory Stimulation ◽  
Brain Regions ◽  
Blood Velocity ◽  
Functional Brain Imaging ◽  
Vascular Events

AbstractThe spatial-temporal sequence of cerebral blood flow (CBF), cerebral blood volume (CBV) and blood velocity changes triggered by neuronal activation is critical for understanding functional brain imaging. This sequence follows a stereotypic pattern of changes across different zones of the vasculature in the olfactory bulb, the first relay of olfaction. However, in the cerebral cortex, where most human brain mapping studies are performed, the timing of activity evoked vascular events remains controversial. Here we utilized a single whisker stimulation model to map out functional hyperemia along vascular arbours from layer II/III to the surface of primary somatosensory cortex, in anesthetized and awake Thy1-GCaMP6 mice. We demonstrate that sensory stimulation triggers an increase in blood velocity within the mid-capillary bed and a dilation of upstream large capillaries, and the penetrating and pial arterioles. We report that under physiological stimulation, response onset times are highly variable across compartments of different vascular arbours. Furthermore, generating transfer functions (TFs) between neuronal Ca2+ and vascular dynamics across different brain states demonstrates that anesthesia decelerates neurovascular coupling (NVC). This spatial-temporal pattern of vascular events demonstrates functional diversity not only between different brain regions but also at the level of different vascular arbours within supragranular layers of the cerebral cortex.

scholarly journals Regional Distribution and Kinetics of Three Sites on the GABAA Receptor: Lack of Effect of Portacaval Shunting

1992 ◽  
Vol 12 (2) ◽  
pp. 334-346 ◽  
Author(s):  
Anke M. Mans ◽  
Kelli M. Kukulka ◽  
Keith J. McAvoy ◽  
Norman C. Rokosz
Keyword(s):  
Kinetic Parameters ◽  
Regional Distribution ◽  
Three Dimensional ◽  
Portacaval Shunt ◽  
Brain Regions ◽  
Significant Heterogeneity ◽  
Heterogeneous Distribution ◽  
Dimensional Reconstruction ◽  
Benzodiazepine Site ◽  
Gaba Neurotransmission

The regional distribution of binding sites on the GABAA receptor and their kinetic parameters were measured by quantitative autoradiography in brains from normal rats and rats with a portacaval shunt, a model of portal systemic encephalopathy in which GABA neurotransmission may be altered. The ligands used were [3H]flunitrazepam (a benzodiazepine-site agonist), [3H]-Ro 15-1788 (a benzodiazepine-site antagonist), [3H]muscimol (a GABA-site agonist), and [35S] t-butylbicyclo-phosphorothionate (35S-TBPS, a convulsant that binds to a site near the chloride channel). Some brains were analyzed by computerized image analysis and three-dimensional reconstruction. The regional distribution of binding of the benzodiazepines was very similar, but the patterns obtained with [3H]muscimol and [35S]TBPS were different in many areas, suggesting a heterogeneous distribution of several subtypes of the GABAA receptor. The kinetic parameters were determined in brain regions for [3H]flunitrazepam, [3H]Ro15-1788, and [3H]muscimol. For each ligand, the Kd showed a significant heterogeneity among brain regions (at least threefold), contrary to conclusions drawn from earlier studies. In portacaval shunted rats, binding of all four ligands was essentially unchanged from that in control rats, indicating that, if there was an abnormality in GABA neurotransmission during portal systemic shunting, it was not reflected by altered binding to the main sites on the GABAA receptor.

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.

Hedonic-Specific Activity in Piriform Cortex During Odor Imagery Mimics That During Odor Perception

2007 ◽  
Vol 98 (6) ◽  
pp. 3254-3262 ◽  
Author(s):  
Moustafa Bensafi ◽  
Noam Sobel ◽  
Rehan M. Khan
Keyword(s):  
Specific Activity ◽  
Piriform Cortex ◽  
Brain Regions ◽  
Specific Pattern ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Odor Perception ◽  
Cortical Areas ◽  
Visual Cortical ◽  
Left Insula

Although it is known that visual imagery is accompanied by activity in visual cortical areas, including primary visual cortex, whether olfactory imagery exists remains controversial. Here we asked whether cue-dependent olfactory imagery was similarly accompanied by activity in olfactory cortex, and in particular whether hedonic-specific patterns of activity evident in olfactory perception would also be present during olfactory imagery. We used functional magnetic resonance imaging to measure activity in subjects who alternated between smelling and imagining pleasant and unpleasant odors. Activity induced by imagining odors mimicked that induced by perceiving real odorants, not only in the particular brain regions activated, but also in its hedonic-specific pattern. For both real and imagined odors, unpleasant stimuli induced greater activity than pleasant stimuli in the left frontal portion of piriform cortex and left insula. These findings combine with findings from other modalities to suggest activation of primary sensory cortical structures during mental imagery of sensory events.

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