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Neurovascular coupling

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https://www.readbyqxmd.com/read/28334149/higher-striatal-iron-concentration-is-linked-to-frontostriatal-underactivation-and-poorer-memory-in-normal-aging
#1
Grégoria Kalpouzos, Benjamín Garzón, Rouslan Sitnikov, Carmel Heiland, Alireza Salami, Jonas Persson, Lars Bäckman
In the brain, intracellular iron is essential for cellular metabolism. However, an overload of free iron is toxic, inducing oxidative stress and cell death. Although an increase of striatal iron has been related to atrophy and impaired cognitive performance, the link between elevated iron and altered brain activity in aging remains unexplored. In a sample of 37 younger and older adults, we examined whether higher striatal iron concentration could underlie age-related differences in frontostriatal activity induced by mental imagery of motor and non-motor scenes, and poorer recall of the scenes...
February 23, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28298143/p450-eicosanoids-and-ros-interplay-in-brain-injury-and-neuroprotection
#2
Xuehong Liu, Catherine M Davis, Nabil J Alkayed
<b>Significance</b>. Eicosanoids are endogenous lipid mediators that play important roles in brain function and disease. Acute brain injury such as that occurs in stroke and traumatic brain injury (TBI) increases the formation of eicosanoids, which in return exacerbate or diminish injury. In chronic neurodegenerative diseases such as Alzheimer's disease (AD) and vascular dementia (VD), eicosanoid synthetic and metabolizing enzymes are altered, disrupting the balance between neuroprotective and neurotoxic eicosanoids...
March 16, 2017: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/28269110/assessment-of-mental-workload-by-eeg-fnirs
#3
Haleh Aghajani, Ahmet Omurtag
We investigated the use of a multimodal functional neuroimaging system in quantifying mental workload of healthy human volunteers. We recorded behavioral performance measures as well as electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) simultaneously from subjects performing n-back tasks. The EEG and fNIRS signals were used in feature generation and classification offline using support vector machines. We examined the classification accuracy of three distinct systems: EEG based; fNIRS based; and Hybrid, which contained features from the first two systems as based on their interactions...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28253268/multiband-multi-echo-imaging-of-simultaneous-oxygenation-and-flow-timeseries-for-resting-state-connectivity
#4
Alexander D Cohen, Andrew S Nencka, R Marc Lebel, Yang Wang
A novel sequence has been introduced that combines multiband imaging with a multi-echo acquisition for simultaneous high spatial resolution pseudo-continuous arterial spin labeling (ASL) and blood-oxygenation-level dependent (BOLD) echo-planar imaging (MBME ASL/BOLD). Resting-state connectivity in healthy adult subjects was assessed using this sequence. Four echoes were acquired with a multiband acceleration of four, in order to increase spatial resolution, shorten repetition time, and reduce slice-timing effects on the ASL signal...
2017: PloS One
https://www.readbyqxmd.com/read/28245297/effect-of-diffuse-luminance-flicker-light-stimulation-on-total-retinal-blood-flow-assessed-with-dual-beam-bidirectional-doppler-oct
#5
Gerold C Aschinger, Leopold Schmetterer, Klemens Fondi, Valentin Aranha Dos Santos, Gerald Seidel, Gerhard Garhöfer, René M Werkmeister
Purpose: We assess the increase in total retinal blood flow (TRBF) induced by flicker stimulation of the human retina in vivo and investigate the flicker induced hyperemia by means of a vascular flow model of the retinal circulation to study neurovascular coupling (NC). Methods: In six healthy subjects, TRBF was measured before and during stimulation with diffuse luminance flicker. Blood flow velocities in retinal vessels were measured via dual-beam bidirectional Doppler Fourier-domain optical coherence tomography (FD-OCT), retinal vessel diameters were assessed based on FD-OCT phase data...
February 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28227336/assessment-of-mental-workload-by-eeg-fnirs
#6
Haleh Aghajani, Ahmet Omurtag, Haleh Aghajani, Ahmet Omurtag, Ahmet Omurtag, Haleh Aghajani
We investigated the use of a multimodal functional neuroimaging system in quantifying mental workload of healthy human volunteers. We recorded behavioral performance measures as well as electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) simultaneously from subjects performing n-back tasks. The EEG and fNIRS signals were used in feature generation and classification offline using support vector machines. We examined the classification accuracy of three distinct systems: EEG based; fNIRS based; and Hybrid, which contained features from the first two systems as based on their interactions...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28219774/dynamic-causal-modelling-revisited
#7
K J Friston, Katrin H Preller, Chris Mathys, Hayriye Cagnan, Jakob Heinzle, Adeel Razi, Peter Zeidman
This paper revisits the dynamic causal modelling of fMRI timeseries by replacing the usual (Taylor) approximation to neuronal dynamics with a neural mass model of the canonical microcircuit. This provides a generative or dynamic causal model of laminar specific responses that can generate haemodynamic and electrophysiological measurements. In principle, this allows the fusion of haemodynamic and (event related or induced) electrophysiological responses. Furthermore, it enables Bayesian model comparison of competing hypotheses about physiologically plausible synaptic effects; for example, does attentional modulation act on superficial or deep pyramidal cells - or both? In this technical note, we describe the resulting dynamic causal model and provide an illustrative application to the attention to visual motion dataset used in previous papers...
February 17, 2017: NeuroImage
https://www.readbyqxmd.com/read/28199396/influence-of-cerebral-blood-vessel-movements-on-the-position-of-perivascular-synapses
#8
Miguel Urrecha, Ignacio Romero, Javier DeFelipe, Angel Merchán-Pérez
Synaptic activity is regulated and limited by blood flow, which is controlled by blood vessel dilation and contraction. Traditionally, the study of neurovascular coupling has mainly focused on energy consumption and oxygen delivery. However, the mechanical changes that blood vessel movements induce in the surrounding tissue have not been considered. We have modeled the mechanical changes that movements of blood vessels cause in neighboring synapses. Our simulations indicate that synaptic densities increase or decrease during vascular dilation and contraction, respectively, near the blood vessel walls...
2017: PloS One
https://www.readbyqxmd.com/read/28196095/depth-dependent-flow-and-pressure-characteristics-in-cortical-microvascular-networks
#9
Franca Schmid, Philbert S Tsai, David Kleinfeld, Patrick Jenny, Bruno Weber
A better knowledge of the flow and pressure distribution in realistic microvascular networks is needed for improving our understanding of neurovascular coupling mechanisms and the related measurement techniques. Here, numerical simulations with discrete tracking of red blood cells (RBCs) are performed in three realistic microvascular networks from the mouse cerebral cortex. Our analysis is based on trajectories of individual RBCs and focuses on layer-specific flow phenomena until a cortical depth of 1 mm. The individual RBC trajectories reveal that in the capillary bed RBCs preferentially move in plane...
February 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28176881/functional-coupling-of-human-microphysiology-systems-intestine-liver-kidney-proximal-tubule-blood-brain-barrier-and-skeletal-muscle
#10
Lawrence Vernetti, Albert Gough, Nicholas Baetz, Sarah Blutt, James R Broughman, Jacquelyn A Brown, Jennifer Foulke-Abel, Nesrin Hasan, Julie In, Edward Kelly, Olga Kovbasnjuk, Jonathan Repper, Nina Senutovitch, Janet Stabb, Catherine Yeung, Nick C Zachos, Mark Donowitz, Mary Estes, Jonathan Himmelfarb, George Truskey, John P Wikswo, D Lansing Taylor
Organ interactions resulting from drug, metabolite or xenobiotic transport between organs are key components of human metabolism that impact therapeutic action and toxic side effects. Preclinical animal testing often fails to predict adverse outcomes arising from sequential, multi-organ metabolism of drugs and xenobiotics. Human microphysiological systems (MPS) can model these interactions and are predicted to dramatically improve the efficiency of the drug development process. In this study, five human MPS models were evaluated for functional coupling, defined as the determination of organ interactions via an in vivo-like sequential, organ-to-organ transfer of media...
February 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28176823/volumetric-spatial-correlations-of-neurovascular-coupling-studied-using-single-pulse-opto-fmri
#11
Isabel N Christie, Jack A Wells, Sergey Kasparov, Alexander V Gourine, Mark F Lythgoe
Neurovascular coupling describes the link between neuronal activity and cerebral blood flow. This relationship has been the subject of intense scrutiny, with most previous work seeking to understand temporal correlations that describe neurovascular coupling. However, to date, the study of spatial correlations has been limited to two-dimensional mapping of neuronal or vascular derived signals emanating from the brain's surface, using optical imaging techniques. Here, we investigate spatial correlations of neurovascular coupling in three dimensions, by applying a single 10 ms pulse of light to trigger optogenetic activation of cortical neurons transduced to express channelrhodopsin2, with concurrent fMRI...
February 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28176165/hemodynamic-changes-associated-with-interictal-spikes-induced-by-acute-models-of-focal-epilepsy-in-rats-a-simultaneous-electrocorticography-and-near-infrared-spectroscopy-study
#12
Viktoriya Osharina, Ardalan Aarabi, Mana Manoochehri, Mahdi Mahmoudzadeh, Fabrice Wallois
Interictal spikes can be generated by blocking GABAA receptor-mediated inhibition. The nature of the hemodynamic activities associated with interictal spikes in acute models of focal epilepsy based on GABA deactivation has not been determined. We analyzed systemic changes in hemodynamic signals associated with interictal spikes generated by acute models of focal epilepsy. Simultaneous ElectroCorticoGraphy (ECoG) and Near-InfraRed Spectroscopy (NIRS) recordings were obtained in vivo from adult Sprague-Dawley rat brain during semi-periodic focal interictal spikes induced by local cortical application of low doses of Penicillin G (PG) and Bicuculline Methiodide (BM) as GABA deactivation agents...
February 7, 2017: Brain Topography
https://www.readbyqxmd.com/read/28161255/neurovascular-uncoupling-in-the-triple-transgenic-model-of-alzheimer-s-disease-impaired-cerebral-blood-flow-response-to-neuronal-derived-nitric-oxide-signaling
#13
Cátia F Lourenço, Ana Ledo, Rui M Barbosa, João Laranjinha
Nitric oxide (NO)-dependent pathways and cerebrovascular dysfunction have been shown to contribute to the cognitive decline and neurodegeneration observed in Alzheimer's disease (AD) but whether they represent initial factors or later changes of the disease is still a matter of debate. In this work, we aimed at investigating whether and to what extent neuronal-derived NO signaling and related neurovascular coupling are impaired along aging in the hippocampus of the triple transgenic mouse model of Alzheimer's Disease (3xTg-AD)...
February 1, 2017: Experimental Neurology
https://www.readbyqxmd.com/read/28159806/oscillatory-lower-body-negative-pressure-impairs-working-memory-task-related-functional-hyperemia-in-healthy-volunteers
#14
Sana Merchant, Marvin S Medow, Paul Visintainer, Courtney Terilli, Julian M Stewart
Neurovascular coupling (NVC) describes the link between an increase in task related neural activity and increased cerebral blood flow denoted "functional hyperemia". We previously showed induced cerebral blood flow oscillations suppressed functional hyperemia; conversely functional hyperemia also suppressed cerebral blood flow oscillations. We used lower body negative pressure (OLBNP) oscillations to force oscillations in middle cerebral artery cerebral blood flow velocity (CBFv). Here, we used N-Back testing, an intellectual memory challenge as a neural activation task, to test the hypothesis that OLBNP-induced oscillatory cerebral blood flow (OCBF) can reduce functional hyperemia and NVC produced by a working memory task, and can interfere with working memory...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28139643/light-controls-cerebral-blood-flow-in-naive-animals
#15
Ravi L Rungta, Bruno-Félix Osmanski, Davide Boido, Mickael Tanter, Serge Charpak
Optogenetics is increasingly used to map brain activation using techniques that rely on functional hyperaemia, such as opto-fMRI. Here we test whether light stimulation protocols similar to those commonly used in opto-fMRI or to study neurovascular coupling modulate blood flow in mice that do not express light sensitive proteins. Combining two-photon laser scanning microscopy and ultrafast functional ultrasound imaging, we report that in the naive mouse brain, light per se causes a calcium decrease in arteriolar smooth muscle cells, leading to pronounced vasodilation, without excitation of neurons and astrocytes...
January 31, 2017: Nature Communications
https://www.readbyqxmd.com/read/28135240/pericyte-degeneration-leads-to-neurovascular-uncoupling-and-limits-oxygen-supply-to-brain
#16
Kassandra Kisler, Amy R Nelson, Sanket V Rege, Anita Ramanathan, Yaoming Wang, Ashim Ahuja, Divna Lazic, Philbert S Tsai, Zhen Zhao, Yi Zhou, David A Boas, Sava Sakadžić, Berislav V Zlokovic
Pericytes are perivascular mural cells of brain capillaries. They are positioned centrally in the neurovascular unit between endothelial cells, astrocytes and neurons. This position allows them to regulate key neurovascular functions of the brain. The role of pericytes in the regulation of cerebral blood flow (CBF) and neurovascular coupling remains, however, under debate. Using loss-of-function pericyte-deficient mice, here we show that pericyte degeneration diminishes global and individual capillary CBF responses to neuronal stimuli, resulting in neurovascular uncoupling, reduced oxygen supply to the brain and metabolic stress...
March 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28112024/inversion-of-neurovascular-coupling-after-subarachnoid-hemorrhage-in%C3%A2-vivo
#17
Matilde Balbi, Masayo Koide, George C Wellman, Nikolaus Plesnila
Subarachnoid hemorrhage (SAH) induces acute changes in the cerebral microcirculation. Recent findings ex vivo suggest neurovascular coupling (NVC), the process that increases cerebral blood flow upon neuronal activity, is also impaired after SAH. The aim of the current study was to investigate whether this occurs also in vivo. C57BL/6 mice were subjected to either sham surgery or SAH by filament perforation. Twenty-four hours later NVC was tested by forepaw stimulation and CO2 reactivity by inhalation of 10% CO2...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28111187/functional-and-oxygen-metabolic-photoacoustic-microscopy-of-the-awake-mouse-brain
#18
Rui Cao, Jun Li, Bo Ning, Naidi Sun, Tianxiong Wang, Zhiyi Zuo, Song Hu
A long-standing challenge in optical neuroimaging has been the assessment of hemodynamics and oxygen metabolism in the awake rodent brain at the microscopic level. Here, we report first-of-a-kind head-restrained photoacoustic microscopy (PAM), which enables simultaneous imaging of the cerebrovascular anatomy, total concentration and oxygen saturation of hemoglobin, and blood flow in awake mice. Combining these hemodynamic measurements allows us to derive two key metabolic parameters-oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO2)...
January 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28090802/functional-deficits-induced-by-cortical-microinfarcts
#19
Philipp M Summers, David A Hartmann, Edward S Hui, Xingju Nie, Rachael L Deardorff, Emilie T McKinnon, Joseph A Helpern, Jens H Jensen, Andy Y Shih
Clinical studies have revealed a strong link between increased burden of cerebral microinfarcts and risk for cognitive impairment. Since the sum of tissue damage incurred by microinfarcts is a miniscule percentage of total brain volume, we hypothesized that microinfarcts disrupt brain function beyond the injury site visible to histological or radiological examination. We tested this idea using a mouse model of microinfarcts, where single penetrating vessels that supply mouse cortex were occluded by targeted photothrombosis...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28089656/how-do-antidepressants-influence-the-bold-signal-in-the-developing-brain
#20
REVIEW
Julia J Harris, Clare Reynell
Depression is a highly prevalent life-threatening disorder, with its first onset commonly occurring during adolescence. Adolescent depression is increasingly being treated with antidepressants, such as fluoxetine. The use of medication during this sensitive period of physiological and cognitive brain development produces neurobiological changes, some of which may outlast the course of treatment. In this review, we look at how antidepressant treatment in adolescence is likely to alter neurovascular coupling and brain energy use and how these changes, in turn, affect our ability to identify neuronal activity changes between participant groups...
December 21, 2016: Developmental Cognitive Neuroscience
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