scholarly journals Hypercapnia increases brain viscoelasticity

2018 ◽  
Vol 39 (12) ◽  
pp. 2445-2455 ◽  
Author(s):  
Stefan Hetzer ◽  
Florian Dittmann ◽  
Karl Bormann ◽  
Sebastian Hirsch ◽  
Axel Lipp ◽  
...  
Keyword(s):  
Blood Flow ◽  
Blood Viscosity ◽  
Brain Function ◽  
Normal Values ◽  
Complex Shear Modulus ◽  
Whole Brain ◽  
Complex Shear ◽  
Cerebral Vasodilatation ◽  
Viscosity Changes

Brain function, the brain’s metabolic activity, cerebral blood flow (CBF), and intracranial pressure are intimately linked within the tightly autoregulated regime of intracranial physiology in which the role of tissue viscoelasticity remains elusive. We applied multifrequency magnetic resonance elastography (MRE) paired with CBF measurements in 14 healthy subjects exposed to 5-min carbon dioxide-enriched breathing air to induce cerebral vasodilatation by hypercapnia. Stiffness and viscosity as quantified by the magnitude and phase angle of the complex shear modulus, | G*| and ϕ, as well as CBF of the whole brain and 25 gray matter sub-regions were analyzed prior to, during, and after hypercapnia. In all subjects, whole-brain stiffness and viscosity increased due to hypercapnia by 3.3 ± 1.9% and 2.0 ± 1.1% which was accompanied by a CBF increase of 36 ± 15%. Post-hypercapnia, | G*| and ϕ reduced to normal values while CBF decreased by 13 ± 15% below baseline. Hypercapnia-induced viscosity changes correlated with CBF changes, whereas stiffness changes did not. The MRE-measured viscosity changes correlated with blood viscosity changes predicted by the Fåhræus–Lindqvist model and microvessel diameter changes from the literature. Our results suggest that brain viscoelastic properties are influenced by microvessel blood flow and blood viscosity: vasodilatation and increased blood viscosity due to hypercapnia result in an increase in MRE values related to viscosity.

SUPER-SYNERGY IN THE BRAIN: THE GRANDMOTHER PERCEPT IS MANIFESTED BY MULTIPLE OSCILLATIONS

2004 ◽  
Vol 14 (02) ◽  
pp. 453-491 ◽  
Author(s):  
EROL BAŞAR ◽  
MURAT ÖZGÖREN ◽  
SIREL KARAKAŞ ◽  
CANAN BAŞAR-EROĞLU
Keyword(s):  
Experimental Work ◽  
Brain Function ◽  
Present Report ◽  
Whole Brain ◽  
Animal Brain ◽  
Oscillatory Dynamics ◽  
New Research ◽  
The Brain ◽  
Face Support

The present report describes the dynamic foundations of long-standing experimental work in the field of oscillatory dynamics in the human and animal brain. It aims to show the role of multiple oscillations in the integrative brain function, memory, and complex perception by a recently introduced conceptional framework: the super-synergy in the whole brain. Results of recent experiments related to the percept of the grandmother-face support our concept of super-synergy in the whole brain in order to explain manifestation of Gestalts and Memory-Stages. This report may also provide new research avenues in macrodynamics of the brain.

scholarly journals Intrinsic connectome organization across temporal scales: New insights from cross-modal approaches

2020 ◽  
Vol 4 (1) ◽  
pp. 1-29 ◽  
Author(s):  
Sepideh Sadaghiani ◽  
Jonathan Wirsich
Keyword(s):  
Brain Function ◽  
Structural Connectivity ◽  
Brain Organization ◽  
Whole Brain ◽  
Intrinsic Connectivity ◽  
Frequency Coupling ◽  
Brain Functional Connectivity ◽  
Brain Behavior ◽  
Cross Frequency Coupling

The discovery of a stable, whole-brain functional connectivity organization that is largely independent of external events has drastically extended our view of human brain function. However, this discovery has been primarily based on functional magnetic resonance imaging (fMRI). The role of this whole-brain organization in fast oscillation-based connectivity as measured, for example, by electroencephalography (EEG) and magnetoencephalography (MEG) is only beginning to emerge. Here, we review studies of intrinsic connectivity and its whole-brain organization in EEG, MEG, and intracranial electrophysiology with a particular focus on direct comparisons to connectome studies in fMRI. Synthesizing this literature, we conclude that irrespective of temporal scale over four orders of magnitude, intrinsic neurophysiological connectivity shows spatial similarity to the connectivity organization commonly observed in fMRI. A shared structural connectivity basis and cross-frequency coupling are possible mechanisms contributing to this similarity. Acknowledging that a stable whole-brain organization governs long-range coupling across all timescales of neural processing motivates researchers to take “baseline” intrinsic connectivity into account when investigating brain-behavior associations, and further encourages more widespread exploration of functional connectomics approaches beyond fMRI by using EEG and MEG modalities.

Intestinal mucosal oxygenation influences absorptive hyperemia

1980 ◽  
Vol 239 (4) ◽  
pp. H489-H489 ◽  
Author(s):  
H. Glenn Bohlen
Keyword(s):  
Blood Flow ◽  
Oxygen Supply ◽  
Bowel Wall ◽  
Normal Values ◽  
Muscle Layer ◽  
Glucose Absorption ◽  
Mucosal Tissue ◽  
Intestinal Villus ◽  
Glucose Exposure

Intestinal villus oxygen tension (PO2) is decreased from normal values of 14-17 to 4-7 mmHg, and blood flow is nearly doubled during glucose absorption. The current study evaluated The role of oxygen supply to the mucosa in the absorptive hyperemia mechanism. With a constant PO2 (40-45 mmHg) over the intestinal muscle layer, the mucosal tissue PO2 increased only 4-5 mmHg, and intestinal blood flow decreased from about 125 to 65% of control (PO2 = 4045) as the mucosal solution PO2 increased from 5 to 75 mmHg. When glucose was present (100 mg/100 mL), mucosal tissue PO2 was s-7 mmHg at mucosal suffusion PO2 of s-75 mmHg. When glucose was present (100 mg/100 mL), mucosal tissue PO2 was s-7 mmHg at mucosal suffusion PO2 of s-75 mmHg. Blood flow in the presence of glucose was 210 and 110% of control at a solution PO2 of 5-10 and 70-75 mmHg. Tissue PO2 in the vicinity of the submucosal series arterioles was only slightly affected by all of the manipulations described. At rest or during glucose exposure, elevation of mucosal solution PO2 caused constriction, and lowering the mucosal solution PO2 caused dilation even though tissue PO2 in the various regions of the bowel wall remained nearly constant. The data indicate that the supply of oxygen available for the tissue rather than the actual tissue PO2 is best correlated to oxygen's role in control of arterioles throughout the intestine during absorptive hyperemia.

Natriuretic Peptides – Addressing the Dilemma of Heart Failure Management

2011 ◽  
Vol 7 (2) ◽  
pp. 104
Author(s):  
Kenneth McDonald ◽  
Ulf Dahlström ◽  
◽  
Keyword(s):  
Heart Failure ◽  
Physical Examination ◽  
Natriuretic Peptides ◽  
Normal Values ◽  
Outpatient Setting ◽  
Heart Failure Management ◽  
Effective Screening ◽  
Specific Symptoms ◽  
Objective Marker

Heart failure (HF) is characterised by non-specific symptoms and unremarkable physical examination; therefore, the need exists for an available objective marker of HF status. Natriuretic peptides (NPs) are a marker that can aid the dilemmas in present-day HF management. More effective screening for clinical deterioration would include changes in brain natriuretic peptide (BNP) levels. Normal values for BNP, <50–100 pg/ml, have excellent negative predictive value (NPV) in excluding HF as a diagnosis. BNP values that are significantly elevated, e.g. >500 pg/ml, make the diagnosis of HF more likely. There are now established and emerging uses for NPs in managing HF in the community. These include the role of NPs at the time of possible new presentation of HF, its role in prognostication and, finally, the increasing interest in using NPs to guide therapy in the outpatient setting.

Role of blood flow and impaired autoregulation in the pathogenesis of diabetic retinopathy

Diabetes ◽  
1995 ◽  
Vol 44 (6) ◽  
pp. 603-607 ◽  
Author(s):  
E. M. Kohner ◽  
V. Patel ◽  
S. M. Rassam
Keyword(s):  
Blood Flow ◽  
Diabetic Retinopathy

Exercise with blood flow restriction as a new tool for health improvement in hypertensive elderly women: the role of purinergic enzymes

2020 ◽  
Vol 60 (11) ◽  
Author(s):  
Aline Mânica ◽  
Clodoaldo A. De SÁ ◽  
Angélica Barili ◽  
Vanessa S. Corralo ◽  
Beatriz S. Bonadiman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Elderly Women ◽  
Blood Flow Restriction ◽  
Health Improvement ◽  
Flow Restriction

Microbiota-Immune System Interactions in Human Neurological Disorders

2020 ◽  
Vol 19 (7) ◽  
pp. 509-526
Author(s):  
Qin Huang ◽  
Fang Yu ◽  
Di Liao ◽  
Jian Xia
Keyword(s):  
Immune System ◽  
Gut Microbiota ◽  
Neurological Disorders ◽  
Brain Function ◽  
Neurological Diseases ◽  
Host Immune System ◽  
Gut Dysbiosis ◽  
Characteristic Features ◽  
Novel Therapeutic Strategies

: Recent studies implicate microbiota-brain communication as an essential factor for physiology and pathophysiology in brain function and neurodevelopment. One of the pivotal mechanisms about gut to brain communication is through the regulation and interaction of gut microbiota on the host immune system. In this review, we will discuss the role of microbiota-immune systeminteractions in human neurological disorders. The characteristic features in the development of neurological diseases include gut dysbiosis, the disturbed intestinal/Blood-Brain Barrier (BBB) permeability, the activated inflammatory response, and the changed microbial metabolites. Neurological disorders contribute to gut dysbiosis and some relevant metabolites in a top-down way. In turn, the activated immune system induced by the change of gut microbiota may deteriorate the development of neurological diseases through the disturbed gut/BBB barrier in a down-top way. Understanding the characterization and identification of microbiome-immune- brain signaling pathways will help us to yield novel therapeutic strategies by targeting the gut microbiome in neurological disease.

Role of Nitric Oxide on Papillary Blood Flow and Pressure Natriuresis

Hypertension ◽  
1995 ◽  
Vol 25 (3) ◽  
pp. 408-414 ◽  
Author(s):  
Francisco J. Fenoy ◽  
Paloma Ferrer ◽  
Luis Carbonell ◽  
Miguel García-Salom
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Pressure Natriuresis
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