Polarographic Electrode Measures of Cerebral Tissue Oxygenation: Implications for Functional Brain Imaging

Bartlett, Kate; Saka, Mohamad; Jones, Myles

doi:10.3390/s8127649

Cited by 9 publications

(6 citation statements)

References 88 publications

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“…Regional metabolic activity in the brain, which is the primary mechanism that satisfies the energetic demands of the brain, 7,8 generates heat and increases local brain temperature concurrent with cerebral blood flow changes. 9 Temperature changes may be more closely related to actual neural activity than cerebral blood flow changes.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous infrared thermal imaging and laser speckle imaging of brain temperature and cerebral blood flow in rats

2018

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Infrared thermal imaging of brain temperature changes is useful for evaluating cortical activity and disease states, such as stroke. However, the changes depend on a balance between changes in heat generation from metabolism and in heat convection related to blood flow. To discriminate between these effects and gain a clearer understanding of neurovascular metabolic coupling, brain temperature imaging must be improved to measure temperature and blood flow simultaneously. We develop an imaging technique that shows a twodimensional (2-D) distribution of absolute brain temperature and relative cerebral blood flow changes in anesthetized rats by combining infrared thermal imaging with laser speckle imaging. The changes in brain metabolism and cerebral blood flow are achieved using two different anesthetics (isoflurane and α-chloralose) to evaluate our system. Isoflurane increased cerebral blood flow but decreased metabolism, whereas α-chloralose decreased both parameters. This technique enables simultaneous visualization of brain surface changes in temperature and cerebral blood flow in the same regions. This imaging system will permit further study of neurovascular metabolic coupling in normal and diseased brains.

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Section: Introductionmentioning

confidence: 99%

Simultaneous infrared thermal imaging and laser speckle imaging of brain temperature and cerebral blood flow in rats

2018

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“…Recent in-vivo studies using microelectrodes to measure cerebral tissue O 2 in real-time during sensory stimulation have begun to address these issues (Ances et al, 2001;Masamoto et al, 2003Masamoto et al, , 2008Offenhauser et al, 2005). Results from such experiments can be compared with both optical and fMRI imaging data in order to understand the important relationship between metabolic and haemodynamic changes associated with increases in neuronal activity (Bartlett et al, 2008). While such comparisons have yielded useful insights into these processes a significant limitation is that data are being compared across different experiments.…”

Section: Introductionmentioning

confidence: 99%

Real-time electrochemical monitoring of brain tissue oxygen: A surrogate for functional magnetic resonance imaging in rodents

et al. 2010

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Long-term in-vivo electrochemistry (LIVE) enables real-time monitoring and measurement of brain metabolites. In this study we have simultaneously obtained blood oxygenation level dependent (BOLD) fMRI and amperometric tissue O 2 data from rat cerebral cortex, during both increases and decreases in inspired O 2 content. BOLD and tissue O 2 measurements demonstrated close correlation (r = 0.7898) during complete (0%) O 2 removal, with marked negative responses occurring ca. 30 s after the onset of O 2 removal. Conversely, when the inspired O 2 was increased (50, 70 and 100% O 2 for 1 min) similar positive rapid changes (ca. 15 s) in both the BOLD and tissue O 2 signals were observed. These findings demonstrate, for the first time, the practical feasibility of obtaining real-time metabolite information during fMRI acquisition, and that tissue O 2 concentration monitored using an O 2 sensor can serve as an index of changes in the magnitude of the BOLD response. As LIVE O 2 sensors can be used in awake animals performing specific behavioural tasks the technique provides a viable animal surrogate of human fMRI experimentation.

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“…Although it has long been presumed that oxidative metabolism is the primary mechanism to satisfy the brain's energetic demands, the influence and dynamics of oxygen supply remain ambiguous (Bartlett et al, 2008;Riera et al, 2008). During both resting and activated conditions, the blood's supply of oxygen exceeds the brain's energetic demand.…”

Section: Introductionmentioning

confidence: 99%

Microvascular Oxygen Tension and Flow Measurements in Rodent Cerebral Cortex during Baseline Conditions and Functional Activation

Yaseen

Srinivasan

Sakadžić

et al. 2010

J Cereb Blood Flow Metab

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Measuring cerebral oxygen delivery and metabolism microscopically is important for interpreting macroscopic functional magnetic resonance imaging (fMRI) data and identifying pathological changes associated with stroke, Alzheimer's disease, and brain injury. Here, we present simultaneous, microscopic measurements of cerebral blood flow (CBF) and oxygen partial pressure (pO 2 ) in cortical microvessels of anesthetized rats under baseline conditions and during somatosensory stimulation. Using a custom-built imaging system, we measured CBF with Fourier-domain optical coherence tomography (OCT), and vascular pO 2 with confocal phosphorescence lifetime microscopy. Cerebral blood flow and pO 2 measurements displayed heterogeneity over distances irresolvable with fMRI and positron emission tomography. Baseline measurements indicate O 2 extraction from pial arterioles and homogeneity of ascending venule pO 2 despite large variation in microvessel flows. Oxygen extraction is linearly related to flow in ascending venules, suggesting that flow in ascending venules closely matches oxygen demand of the drained territory. Oxygen partial pressure and relative CBF transients during somatosensory stimulation further indicate arteriolar O 2 extraction and suggest that arterioles contribute to the fMRI blood oxygen level dependent response. Understanding O 2 supply on a microscopic level will yield better insight into brain function and the underlying mechanisms of various neuropathologies. Keywords: cerebral blood flow; fMRI; microscopy; optical imaging; oxygen IntroductionBrain tissue relies heavily upon a constant and dependable supply of metabolites such as oxygen and glucose. Under normal resting conditions, neural activity and cerebral blood flow (CBF) are tightly coupled, providing steady and sufficient amounts of these metabolites while removing carbon dioxide, heat, and other byproducts (Sokoloff, 1992).Although it has long been presumed that oxidative metabolism is the primary mechanism to satisfy the brain's energetic demands, the influence and dynamics of oxygen supply remain ambiguous (Bartlett et al, 2008;Riera et al, 2008). During both resting and activated conditions, the blood's supply of oxygen exceeds the brain's energetic demand. Numerous studies have demonstrated that the brain's hemodynamic response to evoked functional stimulation, which consists of increases in CBF, cerebral blood volume (CBV), and cerebral metabolic rate of oxygen (CMRO 2 ), involves the dynamic uncoupling of CBF and oxygen consumption, with disproportionately larger increases in CBF compared with CMRO 2 . Using techniques such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and near infrared spectroscopy (NIRS), these investigations have demonstrated that evoked functional stimulation yields increases in CBF between 1.5 and 6 times larger than CMRO 2 increases (Boas et al, 2003;Leontiev et al, 2007;Vafaee and Gjedde, 2004 The role of the hemodynamic response, in particular, the role of increased vascula...

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Polarographic Electrode Measures of Cerebral Tissue Oxygenation: Implications for Functional Brain Imaging

Cited by 9 publications

References 88 publications

Simultaneous infrared thermal imaging and laser speckle imaging of brain temperature and cerebral blood flow in rats

Simultaneous infrared thermal imaging and laser speckle imaging of brain temperature and cerebral blood flow in rats

Real-time electrochemical monitoring of brain tissue oxygen: A surrogate for functional magnetic resonance imaging in rodents

Microvascular Oxygen Tension and Flow Measurements in Rodent Cerebral Cortex during Baseline Conditions and Functional Activation

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