Non-invasive optical spectroscopy and imaging of human brain function

Trends in Neurosciences, Год журнала: 1997, Номер 20(10), С. 435 - 442

Опубликована: Окт. 1, 1997

Brain activity is associated with changes in optical properties of brain tissue. Optical measurements during activation can assess haemoglobin oxygenation, cytochrome-c-oxidase redox state, and two types light scattering reflecting either membrane potential (fast signal) or cell swelling (slow signal), respectively. In previous studies exposed tissue, imaging has been achieved at high temporal microscopical spatial resolution. Now, using near-infrared that penetrate biological tissue reasonably well, it become possible to human subjects through the intact skull non-invasively. After early employing single-site spectroscopy, first devices are being applied successfully for low-resolution functional imaging. Advantages methods include biochemical specificity, a resolution millisecond range, measuring intracellular intravascular events simultaneously portability enabling bedside examinations.

Язык: Английский

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Dynamic Imaging of Cerebral Blood Flow Using Laser Speckle

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 2001, Номер 21(3), С. 195 - 201

Опубликована: Март 1, 2001

A method for dynamic, high-resolution cerebral blood flow (CBF) imaging is presented in this article. By illuminating the cortex with laser light and resulting speckle pattern, relative CBF images tens of microns spatial millisecond temporal resolution are obtained. The regional changes measured technique validated through direct comparison conventional laser-Doppler measurements. Using method, dynamic during focal ischemia cortical spreading depression were obtained along electrophysiologic recordings. Upon middle artery (MCA) occlusion, yielded residual gradient encompassing ischemic core, penumbra, oligemic, normally perfused tissues over a 6 × 4 mm area. Successive demonstrated further decrease indicating an expansion zone finely delineated borders. Dynamic revealed 2 to 3 area increased (160% 250%) that propagated velocity mm/min. This easy implement can be used monitor evolution high studies pathophysiology.

Язык: Английский

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Tissue plasminogen activator (tPA) increase neuronal damage after focal cerebral ischemia in wild-type and tPA-deficient mice

Nature Medicine, Год журнала: 1998, Номер 4(2), С. 228 - 231

Опубликована: Фев. 1, 1998

Язык: Английский

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Cerebral protection in homozygous null ICAM-1 mice after middle cerebral artery occlusion. Role of neutrophil adhesion in the pathogenesis of stroke.

Journal of Clinical Investigation, Год журнала: 1996, Номер 97(1), С. 209 - 216

Опубликована: Янв. 1, 1996

Acute neutrophil (PMN) recruitment to postischemic cardiac or pulmonary tissue has deleterious effects in the early reperfusion period, but mechanisms and of influx pathogenesis evolving stroke remain controversial. To investigate whether PMNs contribute adverse neurologic sequelae mortality after stroke, study potential role leukocyte adhesion molecule intercellular molecule-1 (ICAM-1) we used a murine model transient focal cerebral ischemia consisting intraluminal middle artery occlusion for 45 min followed by 22 h reperfusion. PMN accumulation, monitored deposition 111In-labeled tissue, was increased 2.5-fold ipsilateral (infarcted) hemisphere compared with contralateral (noninfarcted) (P < 0.01). Mice immunodepleted neutrophils before surgery demonstrated 3.0-fold reduction infarct volumes 0.001), based on triphenyltetrazolium chloride staining serial sections, improved cortical blood flow (measured laser Doppler), reduced neurological deficit controls. In wild-type mice subjected reperfusion, ICAM-1 mRNA hemisphere, immunohistochemistry localizing expression microvascular endothelium. The investigated homozygous null (ICAM-1 -/-) comparison controls +/+). -/- 3.7-fold volume 0.005), 35% increase survival 0.05), +/+ Cerebral infarcted 3.1-fold greater 0.01), suggesting an important genesis no-reflow. Because PMN-depleted ICAM-1-deficient are relatively resistant ischemia-reperfusion injury, these studies suggest ICAM-1-mediated pathophysiology stroke.

Язык: Английский

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Vascular imprints of neuronal activity: Relationships between the dynamics of cortical blood flow, oxygenation, and volume changes following sensory stimulation

Proceedings of the National Academy of Sciences, Год журнала: 1997, Номер 94(26), С. 14826 - 14831

Опубликована: Дек. 23, 1997

Modern functional neuroimaging methods, such as positron-emission tomography (PET), optical imaging of intrinsic signals, and MRI (fMRI) utilize activity-dependent hemodynamic changes to obtain indirect maps the evoked electrical activity in brain. Whereas PET flow-sensitive map cerebral blood flow (CBF) changes, oxygenation level-dependent areas with concentration deoxygenated hemoglobin (HbR). However, relationship between CBF HbR during activation has never been tested experimentally. Therefore, we investigated this by using spectroscopy laser-Doppler flowmetry techniques, simultaneously, visual cortex anesthetized cats sensory stimulation. We found that earliest microcirculatory change was indeed an increase HbR, whereas lagged more than a second after HbR. The increased accompanied simultaneous total (Hbt), presumably reflecting early volume increase. Hbt 1 2 sec throughout response. These results support notion active neurovascular regulation capillary bed existence delayed, passive process filling.

Язык: Английский

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Cortical Blood Flow and Cerebral Perfusion Pressure in a New Noncraniotomy Model of Subarachnoid Hemorrhage in the Rat

Stroke, Год журнала: 1995, Номер 26(6), С. 1086 - 1092

Опубликована: Июнь 1, 1995

Acute cerebral ischemia after subarachnoid hemorrhage (SAH) is a major cause of morbidity whose precise etiology unclear. The purpose this study was to examine the relationships between perfusion pressure (CPP) and cortical blood flow during SAH using new experimental model in rat.CPP (mean arterial minus intracranial pressure), laser-Doppler flowmetry (LDF), electroencephalogram were continuously recorded 16 ventilated rats. produced by advancing an intraluminal suture from external carotid artery through internal perforate vessel near its bifurcation.Eight rats (50%) died within 24 hours SAH. In all rats, widely distributed throughout basal, convexity, interhemispheric spaces ventricular system. CPP decreased at initial rate 1.1 +/- 0.2 mm Hg/s, reaching nadir 59 9 seconds onset During same period, LDF fell 1.4 0.3%/s (P = NS vs CPP). After nadir, rose 0.4 0.01 but continued fall 0.03%/s < .05 CPP) 21.7 2.5% significantly later than (189.5 39 s SAH, P .05). No correlation found peak changes LDF. Electroencephalogram activity followed LDF, values 289 55 SAH.These findings demonstrate that although reduced causes decrease secondary reductions occurring has reached are caused other factors such as acute vasoconstriction. This noncraniotomy rat several advantages over existing models.

Язык: Английский

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Two-Photon Microscopy as a Tool to Study Blood Flow and Neurovascular Coupling in the Rodent Brain

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 2012, Номер 32(7), С. 1277 - 1309

Опубликована: Фев. 1, 2012

The cerebral vascular system services the constant demand for energy during neuronal activity in brain. Attempts to delineate logic of neurovascular coupling have been greatly aided by advent two-photon laser scanning microscopy image both blood flow and individual cells below surface Here we provide a technical guide imaging rodents. We describe detail surgical procedures required generate cranial windows optical access cortex rats mice use accurately measure cortical vessels concurrent with local cellular activity. further examples on how these techniques can be applied study regulation pathologies such as small-scale stroke.

Язык: Английский

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Cerebral blood flow and autoregulation: current measurement techniques and prospects for noninvasive optical methods

Neurophotonics, Год журнала: 2016, Номер 3(3), С. 031411 - 031411

Опубликована: Июнь 21, 2016

Cerebral blood flow (CBF) and cerebral autoregulation (CA) are critically important to maintain proper brain perfusion supply the with necessary oxygen energy substrates. Adequate is required support normal function, achieve successful aging, navigate acute chronic medical conditions. We review general principles of CBF measurements current techniques measure based on direct intravascular measurements, nuclear medicine, X-ray imaging, magnetic resonance ultrasound techniques, thermal diffusion, optical methods. also for arterial pressure as well theoretical experimental methods assessment CA, including recent approaches techniques. The in clinical practice presented. comprehensive description principles, methods, requirements CA highlights potentially role that noninvasive can play neurovascular health. In fact, have ability provide a noninvasive, quantitative, continuous monitor autoregulation.

Язык: Английский

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Anesthesia and the Quantitative Evaluation of Neurovascular Coupling

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 2012, Номер 32(7), С. 1233 - 1247

Опубликована: Апрель 18, 2012

Anesthesia has broad actions that include changing neuronal excitability, vascular reactivity, and other baseline physiologies eventually modifies the neurovascular coupling relationship. Here, we review effects of anesthesia on spatial propagation, temporal dynamics, quantitative relationship between neural responses to cortical stimulation. Previous studies have shown onset latency evoked cerebral blood flow (CBF) changes is relatively consistent across conditions compared with variations in time-to-peak. This finding indicates mechanism vasodilation less dependent interference, while dynamics are subject this interference. The largely influenced by type dosage anesthesia, including processing, vasoactive signal transmission, reactivity. gap response regions not fully understood require further attention elucidate control CBF supply underlying focal surrounding activity. in-depth understanding elements allows for better decision-making regarding anesthetics used specific models experiments may also help source issues hemodynamic-based neuroimaging techniques.

Язык: Английский

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The Significance of Brain Temperature in Focal Cerebral Ischemia: Histopathological Consequences of Middle Cerebral Artery Occlusion in the Rat

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 1992, Номер 12(3), С. 380 - 389

Опубликована: Май 1, 1992

The purpose of this study was to determine the effect selective modulation brain temperature in experimental settings permanent and reversible middle cerebral artery (MCA) occlusion Sprague–Dawley rats. Three models proximal MCA were used, which brain-temperature modulations could be studied. These included (a) with an initial 30-min period hypotension (30 or 36°C × 4 h), (b) alone (30, 36, 39°C 2 (c) h h). In transient series, intra- postischemic cortical blood flow assessed using a laser–Doppler flowmeter placed over dorsolateral cortex. After 3-day survival, all rats perfusion fixed for histopathological analysis determination infarct volume. animals plus hypotension, no significant difference volume demonstrated between 30 groups. without differences again not demonstrable, but interaction area class shown by repeated-measures analysis, indicating that hypothermia altered topographic pattern infarct. With occlusion, there statistically reduction 30°C group compared Although CBF significantly different among three groups, positively correlated CBF. CBF, turn, intraischemic negatively during ischemic period. findings demonstrate moderate manipulations have greater influence on resulting infarction setting focal ischemia than context vascular occlusion.

Язык: Английский

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