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Neurovascular coupling

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https://www.readbyqxmd.com/read/28437349/a-new-navigational-tool-for-pedicle-screw-placement-in-patients-with-severe-scoliosis-a-pilot-study-to-prove-feasibility-accuracy-and-identify-operative-challenges
#1
Michael Putzier, Patrick Strube, Riccardo Cecchinato, Claudio Lamartina, Eike K Hoff
STUDY DESIGN: Pilot study. OBJECTIVE: To develop and validate the feasibility and accuracy of a newly designed navigational spinal instrument guiding tool for patient-matched thoracic and lumbar pedicle screw placement in patients with severe scoliosis, and to identify intraoperative challenges that may be relevant. SUMMARY OF BACKGROUND DATA: Pedicle screw placement is challenging in severely rotated scoliotic spine with small diameters and asymmetrical shape of the pedicles and vertebrae...
May 2017: Clinical Spine Surgery
https://www.readbyqxmd.com/read/28435052/neurovascular-neuroenergetic-coupling-axis-in-the-brain-master-regulation-by-nitric-oxide-and-consequences-in-aging-and-neurodegeneration
#2
REVIEW
Cátia F Lourenço, Ana Ledo, Rui M Barbosa, João Laranjinha
The strict energetic demands of the brain require that nutrient supply and usage be fine-tuned in accordance with the specific temporal and spatial patterns of ever-changing levels of neuronal activity. This is achieved by adjusting local cerebral blood flow (CBF) as a function of activity level - neurovascular coupling - and by changing how energy substrates are metabolized and shuttled amongst astrocytes and neurons - neuroenergetic coupling. Both activity-dependent increase of CBF and O2 and glucose utilization by active neural cells are inextricably linked, establishing a functional metabolic axis in the brain, the neurovascular-neuroenergetic coupling axis...
April 20, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28419680/bold-neurovascular-coupling-does-not-change-significantly-with-normal-aging
#3
Jack Grinband, Jason Steffener, Qolamreza R Razlighi, Yaakov Stern
Studies of cognitive function that compare the blood oxygenation level dependent (BOLD) signal across age groups often require the assumption that neurovascular coupling does not change with age. Tests of this assumption have produced mixed results regarding the strength of the coupling and its relative time course. Using deconvolution, we found that age does not have a significant effect on the time course of the hemodynamic impulse response function or on the slope of the BOLD versus stimulus duration relationship...
April 17, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28416148/alterations-in-autonomic-cerebrovascular-control-after-spinal-cord-injury
#4
Dong-Il Kim, Can Ozan Tan
Among chronic cardiovascular and metabolic sequelae of spinal cord injury (SCI) is an up-to four-fold increase in the risk of ischemic and hemorrhagic stroke, suggesting that individuals with SCI cannot maintain stable cerebral perfusion. In able-bodied individuals, the cerebral vasculature is able to regulate cerebral perfusion in response to swings in arterial pressure (cerebral autoregulation), blood gases (cerebral vasoreactivity), and neural metabolic demand (neurovascular coupling). This ability depends, at least partly, on intact autonomic function, but high thoracic and cervical spinal cord injuries result in disruption of sympathetic and parasympathetic cerebrovascular control...
April 4, 2017: Autonomic Neuroscience: Basic & Clinical
https://www.readbyqxmd.com/read/28406906/water-diffusion-closely-reveals-neural-activity-status-in-rat-brain-loci-affected-by-anesthesia
#5
Yoshifumi Abe, Tomokazu Tsurugizawa, Denis Le Bihan
Diffusion functional MRI (DfMRI) reveals neuronal activation even when neurovascular coupling is abolished, contrary to blood oxygenation level-dependent (BOLD) functional MRI (fMRI). Here, we show that the water apparent diffusion coefficient (ADC) derived from DfMRI increased in specific rat brain regions under anesthetic conditions, reflecting the decreased neuronal activity observed with local field potentials (LFPs), especially in regions involved in wakefulness. In contrast, BOLD signals showed nonspecific changes, reflecting systemic effects of the anesthesia on overall brain hemodynamics status...
April 2017: PLoS Biology
https://www.readbyqxmd.com/read/28403673/mechanisms-mediating-functional-hyperemia-in-the-brain
#6
Amy R Nippert, Kyle R Biesecker, Eric A Newman
Neuronal activity within the brain evokes local increases in blood flow, a response termed functional hyperemia. This response ensures that active neurons receive sufficient oxygen and nutrients to maintain tissue function and health. In this review, we discuss the functions of functional hyperemia, the types of vessels that generate the response, and the signaling mechanisms that mediate neurovascular coupling, the communication between neurons and blood vessels. Neurovascular coupling signaling is mediated primarily by the vasoactive metabolites of arachidonic acid (AA), by nitric oxide, and by K(+)...
April 1, 2017: Neuroscientist: a Review Journal Bringing Neurobiology, Neurology and Psychiatry
https://www.readbyqxmd.com/read/28401931/early-neurovascular-dysfunction-in-a-transgenic-rat-model-of-alzheimer-s-disease
#7
Illsung L Joo, Aaron Y Lai, Paolo Bazzigaluppi, Margaret M Koletar, Adrienne Dorr, Mary E Brown, Lynsie A M Thomason, John G Sled, JoAnne McLaurin, Bojana Stefanovic
Alzheimer's disease (AD), pathologically characterized by amyloid-β peptide (Aβ) accumulation, neurofibrillary tangle formation, and neurodegeneration, is thought to involve early-onset neurovascular abnormalities. Hitherto studies on AD-associated neurovascular injury have used animal models that exhibit only a subset of AD-like pathologies and demonstrated some Aβ-dependent vascular dysfunction and destabilization of neuronal network. The present work focuses on the early stage of disease progression and uses TgF344-AD rats that recapitulate a broader repertoire of AD-like pathologies to investigate the cerebrovascular and neuronal network functioning using in situ two-photon fluorescence microscopy and laminar array recordings of local field potentials, followed by pathological analyses of vascular wall morphology, tau hyperphosphorylation, and amyloid plaques...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28396293/the-impact-of-ultra-high-field-mri-on-cognitive-and-computational-neuroimaging
#8
Federico De Martino, Essa Yacoub, Valentin Kemper, Michelle Moerel, Kamil Uludag, Peter De Weerd, Kamil Ugurbil, Rainer Goebel, Elia Formisano
The ability to measure functional brain responses non-invasively with ultra high field MRI (7 T and above) represents a unique opportunity in advancing our understanding of the human brain. Compared to lower fields (3 T and below), ultra high field MRI has an increased sensitivity, which can be used to acquire functional images with greater spatial resolution, and greater specificity of the blood oxygen level dependent (BOLD) signal to the underlying neuronal responses. Together, increased resolution and specificity enable investigating brain functions at a submillimeter scale, which so far could only be done with invasive techniques...
April 7, 2017: NeuroImage
https://www.readbyqxmd.com/read/28393884/novel-wavelet-real-time-analysis-of-neurovascular-coupling-in-neonatal-encephalopathy
#9
Lina F Chalak, Fenghua Tian, Beverley Adams-Huet, Diana Vasil, Abbot Laptook, Takashi Tarumi, Rong Zhang
Birth asphyxia constitutes a major global public health burden for millions of infants, despite hypothermia therapy. There is a critical need for real time surrogate markers of therapeutic success, to aid in patient selection and/or modification of interventions in neonatal encephalopathy (NE). This is a proof of concept study aiming to quantify neurovascular coupling (NVC) using wavelet analysis of the dynamic coherence between amplitude-integrated electroencephalography (aEEG) and near-infrared spectroscopy in NE...
April 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28387139/intracortical-electrophysiological-correlates-of-blood-flow-after-severe-sah-a-multimodality-monitoring-study
#10
Brandon Foreman, David Albers, J Michael Schmidt, Cristina Maria Falo, Angela Velasquez, E Sander Connolly, Jan Claassen
Subarachnoid hemorrhage (SAH) is a devastating form of stroke. Approximately one in four patients develop progressive neurological deterioration and silent infarction referred to as delayed cerebral ischemia (DCI). DCI is a complex, multifactorial secondary brain injury pattern and its pathogenesis is not fully understood. We aimed to study the relationship between cerebral blood flow (CBF) and neuronal activity at both the cortex and in scalp using electroencephalography (EEG) in poor-grade SAH patients undergoing multimodality intracranial neuromonitoring...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28369176/glial-calcium-waves-are-triggered-by-seizure-activity-and-not-essential-for-initiating-ictal-onset-or-neurovascular-coupling
#11
Eliza Baird-Daniel, Andy G S Daniel, Michael Wenzel, Dan Li, Jyun-You Liou, Philippe Laffont, Mingrui Zhao, Rafael Yuste, Hongtao Ma, Theodore H Schwartz
It has been postulated that glia play a critical role in modifying neuronal activity, mediating neurovascular coupling, and in seizure initiation. We investigated the role of glia in ictogenesis and neurovascular coupling through wide-field multicell and 2-photon single cell imaging of calcium and intrinsic signal imaging of cerebral blood volume in an in vivo rat model of focal neocortical seizures. Ictal events triggered a slowly propagating glial calcium wave that was markedly delayed after both neuronal and hemodynamic onset...
March 21, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28355608/new-wavelet-neurovascular-bundle-for-bedside-evaluation-of-cerebral-autoregulation-and-neurovascular-coupling-in-newborns-with-hypoxic-ischemic-encephalopathy
#12
Lina F Chalak, Rong Zhang
Neonatal encephalopathy (NE) resulting from birth asphyxia constitutes a major global public health burden for millions of infants every year, and despite therapeutic hypothermia, half of these neonates have poor neurological outcomes. As new neuroprotective interventions are being studied in clinical trials, there is a critical need to establish physiological surrogate markers of therapeutic efficacy, to guide patient selection and/or to modify the therapeutic intervention. The challenge in the field of neonatal brain injury has been the difficulty of clinically discerning NE severity within the short therapeutic window after birth or of analyzing the dynamic aspects of the cerebral circulation in sick NE newborns...
March 30, 2017: Developmental Neuroscience
https://www.readbyqxmd.com/read/28334149/higher-striatal-iron-concentration-is-linked-to-frontostriatal-underactivation-and-poorer-memory-in-normal-aging
#13
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-reactive-oxygen-species-interplay-in-brain-injury-and-neuroprotection
#14
Xuehong Liu, Catherine M Davis, Nabil J Alkayed
SIGNIFICANCE: Eicosanoids are endogenous lipid mediators that play important roles in brain function and disease. Acute brain injury such as that which occurs in stroke and traumatic brain injury increases the formation of eicosanoids, which, in turn, exacerbate or diminish injury. In chronic neurodegenerative diseases such as Alzheimer's disease and vascular dementia (VD), eicosanoid synthetic and metabolizing enzymes are altered, disrupting the balance between neuroprotective and neurotoxic eicosanoids...
April 20, 2017: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/28269110/assessment-of-mental-workload-by-eeg-fnirs
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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