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Neurovascular coupling

Anusha Mishra, James P Reynolds, Yang Chen, Alexander V Gourine, Dmitri A Rusakov, David Attwell
Active neurons increase their energy supply by dilating nearby arterioles and capillaries. This neurovascular coupling underlies blood oxygen level-dependent functional imaging signals, but its mechanism is controversial. Canonically, neurons release glutamate to activate metabotropic glutamate receptor 5 (mGluR5) on astrocytes, evoking Ca(2+) release from internal stores, activating phospholipase A2 and generating vasodilatory arachidonic acid derivatives. However, adult astrocytes lack mGluR5, and knockout of the inositol 1,4,5-trisphosphate receptors that release Ca(2+) from stores does not affect neurovascular coupling...
October 24, 2016: Nature Neuroscience
Julien Pichette, Audrey Laurence, Leticia Angulo, Frederic Lesage, Alain Bouthillier, Dang Khoa Nguyen, Frederic Leblond
Using light, we are able to visualize the hemodynamic behavior of the brain to better understand neurovascular coupling and cerebral metabolism. In vivo optical imaging of tissue using endogenous chromophores necessitates spectroscopic detection to ensure molecular specificity as well as sufficiently high imaging speed and signal-to-noise ratio, to allow dynamic physiological changes to be captured, isolated, and used as surrogate of pathophysiological processes. An optical imaging system is introduced using a 16-bands on-chip hyperspectral camera...
October 2016: Neurophotonics
Iliya Sigal, Margaret M Koletar, Dene Ringuette, Raanan Gad, Melanie Jeffrey, Peter L Carlen, Bojana Stefanovic, Ofer Levi
We report on a miniature label-free imaging system for monitoring brain blood flow and blood oxygenation changes in awake, freely behaving rats. The device, weighing 15 grams, enables imaging in a ∼ 2 × 2 mm field of view with 4.4 μm lateral resolution and 1 - 8 Hz temporal sampling rate. The imaging is performed through a chronically-implanted cranial window that remains optically clear between 2 to > 6 weeks after the craniotomy. This imaging method is well suited for longitudinal studies of chronic models of brain diseases and disorders...
September 1, 2016: Biomedical Optics Express
Brad A Sutherland, Jonas C Fordsmann, Chris Martin, Ain A Neuhaus, Brent M Witgen, Henning Piilgaard, Micael Lønstrup, Yvonne Couch, Nicola R Sibson, Martin Lauritzen, Alastair M Buchan
Hyperacute changes in cerebral blood flow during cerebral ischaemia and reperfusion are important determinants of injury. Cerebral blood flow is regulated by neurovascular coupling, and disruption of neurovascular coupling contributes to brain plasticity and repair problems. However, it is unknown how neurovascular coupling is affected hyperacutely during cerebral ischaemia and reperfusion. We have developed a remote middle cerebral artery occlusion model in the rat, which enables multi-modal assessment of neurovascular coupling immediately prior to, during and immediately following reperfusion...
September 14, 2016: Journal of Cerebral Blood Flow and Metabolism
Pierluigi Iacono, Maurizio Battaglia Parodi, Carlo La Spina, Giampaolo Zerbini, Francesco Bandello
PURPOSE: To evaluate in vivo the vascular anatomy and functionality of early manifestation retinitis pigmentosa (RP) by means of a dynamic and static vessel analyzer. METHODS: Fourteen patients with early RP and 14 normal subjects were consecutively enrolled in this observational, prospective study. Each patient underwent a complete ophthalmologic examination, including dynamic and static retinal vessel analysis using the Dynamic Vessel Analyzer. RESULTS: The patients with RP and the control group were well matched in age and sex...
September 13, 2016: Retina
Anusha Mishra
Astrocytes are the most common glial cells in the brain with fine processes and endfeet that intimately contact both neuronal synapses and the cerebral vasculature. They play an important role in mediating neurovascular coupling (NVC) via several astrocytic Ca(2+) -dependent signalling pathways such as K(+) release through BK channels, and the production and release of arachidonic acid metabolites. They are also involved in maintaining the resting tone of the cerebral vessels by releasing ATP and COX-1 derivatives...
September 13, 2016: Journal of Physiology
George H Denfield, Paul G Fahey, Jacob Reimer, Andreas S Tolias
O'Herron et al. (2016) perform two-photon imaging of vascular and neural responses in cat and rodent primary visual cortex to investigate the limits of neurovascular coupling. Their results suggest important constraints on making inferences about neuronal responses from hemodynamic activity.
September 7, 2016: Neuron
Matthew Caldwell, Felix Scholkmann, Ursula Wolf, Martin Wolf, Clare Elwell, Ilias Tachtsidis
Haemodynamics-based neuroimaging is widely used to study brain function. Regional blood flow changes characteristic of neurovascular coupling provide an important marker of neuronal activation. However, changes in systemic physiological parameters such as blood pressure and concentration of CO2 can also affect regional blood flow and may confound haemodynamics-based neuroimaging. Measurements with functional near-infrared spectroscopy (fNIRS) may additionally be confounded by blood flow and oxygenation changes in extracerebral tissue layers...
August 31, 2016: NeuroImage
Dimitrios Baltzis, Jody R Dushay, Jordan Loader, Jim Wu, Robert L Greenman, Matthieu Roustit, Aristidis Veves
CONTEXT: The dipeptidyl peptidase-4 (DPP-4) inhibitor, linagliptin, possesses pleiotropic vasodilatory, antioxidant, and anti-inflammatory properties in animals, independent of its glucose-lowering properties. While large randomized clinical trials are being conducted to better evaluate the efficacy and safety of linagliptin on cardiovascular outcomes, little is known about its effects on vascular function in humans. OBJECTIVE: To evaluate the effect of linagliptin on surrogates of vascular and mitochondrial function...
September 1, 2016: Journal of Clinical Endocrinology and Metabolism
Julia K Brynildsen, Li-Ming Hsu, Thomas J Ross, Elliot A Stein, Yihong Yang, Hanbing Lu
Anesthetics are commonly used in preclinical functional MRI studies. It is well-appreciated that proper choice of anesthetics is of critical importance for maintaining a physiologically normal range of autonomic functioning. A recent study, using a low dose of dexmedetomidine (active isomer of medetomidine) in combination with a low dose of isoflurane, suggested stable measurements across repeated fMRI experiments in individual animals with each session lasting up to several hours. The rat default mode network has been successfully identified using this preparation, indicating that this protocol minimally disturbs brain network functions...
August 28, 2016: Magnetic Resonance Imaging
Wei Song, Qiang Xu, Yang Zhang, Yang Zhan, Wei Zheng, Liang Song
The ability to obtain comprehensive structural and functional information from intact biological tissue in vivo is highly desirable for many important biomedical applications, including cancer and brain studies. Here, we developed a fully integrated multimodal microscopy that can provide photoacoustic (optical absorption), two-photon (fluorescence), and second harmonic generation (SHG) information from tissue in vivo, with intrinsically co-registered images. Moreover, using a delicately designed optical-acoustic coupling configuration, a high-frequency miniature ultrasonic transducer was integrated into a water-immersion optical objective, thus allowing all three imaging modalities to provide a high lateral resolution of ~290 nm with reflection-mode imaging capability, which is essential for studying intricate anatomy, such as that of the brain...
2016: Scientific Reports
Ying Ma, Mohammed A Shaik, Sharon H Kim, Mariel G Kozberg, David N Thibodeaux, Hanzhi T Zhao, Hang Yu, Elizabeth M C Hillman
Although modern techniques such as two-photon microscopy can now provide cellular-level three-dimensional imaging of the intact living brain, the speed and fields of view of these techniques remain limited. Conversely, two-dimensional wide-field optical mapping (WFOM), a simpler technique that uses a camera to observe large areas of the exposed cortex under visible light, can detect changes in both neural activity and haemodynamics at very high speeds. Although WFOM may not provide single-neuron or capillary-level resolution, it is an attractive and accessible approach to imaging large areas of the brain in awake, behaving mammals at speeds fast enough to observe widespread neural firing events, as well as their dynamic coupling to haemodynamics...
October 5, 2016: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
C Lecrux, E Hamel
Brain imaging techniques that use vascular signals to map changes in neuronal activity, such as blood oxygenation level-dependent functional magnetic resonance imaging, rely on the spatial and temporal coupling between changes in neurophysiology and haemodynamics, known as 'neurovascular coupling (NVC)'. Accordingly, NVC responses, mapped by changes in brain haemodynamics, have been validated for different stimuli under physiological conditions. In the cerebral cortex, the networks of excitatory pyramidal cells and inhibitory interneurons generating the changes in neural activity and the key mediators that signal to the vascular unit have been identified for some incoming afferent pathways...
October 5, 2016: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Erin L Mazerolle, Yuhan Ma, David Sinclair, G Bruce Pike
Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) studies of patients with cerebrovascular disease have largely ignored the confounds associated with abnormal cerebral blood flow, vascular reactivity and neurovascular coupling. We studied BOLD fMRI activation and cerebrovascular reactivity in moyamoya disease. To characterize the impact of remote vascular demands on BOLD fMRI measurements, we varied the vascular territories engaged by manipulating the experimental task performed by the participants...
August 30, 2016: Clinical Physiology and Functional Imaging
Taeyoon Son, Benquan Wang, Damber Thapa, Yiming Lu, Yanjun Chen, Dingcai Cao, Xincheng Yao
Blood flow changes are highly related to neural activities in the retina. It has been reported that neural activity increases when flickering light stimulation of the retina is used. It is known that blood flow changes with flickering light stimulation can be altered in patients with vascular disease and that measurement of flicker-induced vasodilatation is an easily applied tool for monitoring functional microvascular alterations. However, details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood due to the limitation of existing techniques...
August 1, 2016: Biomedical Optics Express
Natasha Bray, Fiona E Burrows, Myles Jones, Jason Berwick, Stuart M Allan, Ingo Schiessl
BACKGROUND: Neurovascular coupling describes the mechanism by which the energy and oxygen demand arising from neuronal activity is met by an increase in regional blood flow, known as the haemodynamic response. Interleukin 1 (IL-1) is a pro-inflammatory cytokine and an important mediator of neuronal injury, though mechanisms through which IL-1 exerts its effects in the brain are not fully understood. In this study, we set out to investigate if increased cerebral levels of IL-1 have a negative effect on the neurovascular coupling in the cortex in response to sensory stimulation...
2016: Journal of Neuroinflammation
Qian Li, Lin Li, Tianhao Yu, Qingliang Zhao, Chuanqing Zhou, Xinyu Chai
A vascular tree extraction algorithm is proposed to automatically extract independent and complete vascular trees from both background and other crossed vascular trees for photoacoustic microscopy (PAM) imaging. Extracted parameters include vascular tree centerline, diameters, boundaries and three-dimensional (3-D) direction along the tree. Based on the concept of blood vessel tracking, the proposed algorithm extracts complete vascular trees by utilizing a ray casting framework to realize functions which includes vessel direction estimation, vessel branching detection and vessel crossover point detection...
August 22, 2016: Journal of Biophotonics
Jungmi Moon, Yejin Ha, Misun Kim, Jeongeun Sim, Youngmi Lee, Minah Suh
In this work, we developed a dual amperometric/potentiometric microsensor for sensing nitric oxide (NO) and potassium ion (K(+)). The dual NO/K(+) sensor was prepared based on a dual recessed electrode possessing Pt (diameter, 50 μm) and Ag (diameter, 76.2 μm) microdisks. The Pt disk surface (WE1) was modified with electroplatinization and the following coating with fluorinated xerogel; and the Ag disk surface (WE2) was oxidized to AgCl on which K(+) ion selective membrane was loaded subsequent to the silanization...
September 20, 2016: Analytical Chemistry
Ulrike Hoffmann, Huaxin Sheng, Cenk Ayata, David S Warner
Anesthetics have enabled major advances in development of experimental models of human stroke. Yet, their profound pharmacologic effects on neural function can confound the interpretation of experimental stroke research. Anesthetics have species-, drug-, and dose-specific effects on cerebral blood flow and metabolism, neurovascular coupling, autoregulation, ischemic depolarizations, excitotoxicity, inflammation, neural networks, and numerous molecular pathways relevant for stroke outcome. Both preconditioning and postconditioning properties have been described...
October 2016: Translational Stroke Research
Kun-Wei Wu, Zeng-Wei Kou, Jia-Lin Mo, Xu-Xu Deng, Feng-Yan Sun
This study examined the effect of neuron-endothelial coupling on the survival of neurons after ischemia and the possible mechanism underlying that effect. Whole-cell patch-clamp experiments were performed on cortical neurons cultured alone or directly cocultured with brain microvascular endothelial cells (BMEC). Propidium iodide (PI) and NeuN staining were performed to examine neuronal death following oxygen and glucose deprivation (OGD). We found that the neuronal transient outward potassium currents (IA) decreased in the coculture system, whereas the outward delayed-rectifier potassium currents (IK) did not...
August 12, 2016: Neuroscience
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