Oxygenation of the cat primary visual cortex

Padnick, Lissa B.; Linsenmeier, Robert A.; Goldstick, Thomas K.

doi:10.1152/jappl.1999.86.5.1490

Cited by 19 publications

(17 citation statements)

References 27 publications

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“…The average pO 2 (measured in three animals; excluding pial arterioles) decreased by ~10 mmHg moving from the pial veins down to a depth of ~240 µm. This observation supported previous findings6, 27 showing a relatively rapid initial decrease of tissue pO 2 with cortical depth. Interestingly, we also observed an average pO 2 increase of ~7 mmHg towards the cortical surface in the three ascending venules (Fig.…”

Section: Resultssupporting

confidence: 93%

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue

et al. 2010

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The ability to measure oxygen partial pressure (pO2) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO2 measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here, we report the first practical in vivo two-photon high-resolution pO2 measurements in small rodents’ cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 µm, sub-second temporal resolution and requires low probe concentration. Most importantly, the properties of the probe allowed for the first direct high-resolution measurement of cortical extravascular (tissue) pO2, opening numerous possibilities for functional metabolic brain studies.

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Section: Resultssupporting

confidence: 93%

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue

et al. 2010

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“…The resulting spectrum had a dominant peak at about 5 cpm and gradually falling power at higher frequencies. While this is the only demonstration of this in the retina, we and others have observed similar fluctuations at similar frequencies in the brain of anesthetized animals (Hudetz et al, 1998; Manil et al, 1984; Padnick et al, 1999) and awake rabbits (Linsenmeier et al, 2016a). Generally these fluctuations are believed to reflect ongoing local fluctuations of vascular resistance, termed vasomotion (Aalkjaer et al, 2011), but there is no direct proof of this in the retina.…”

Section: Fundamentals Of O2 Supply To the Retinasupporting

confidence: 78%

Retinal oxygen: from animals to humans

Linsenmeier

Zhang

2017

Progress in Retinal and Eye Research

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176

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This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O2 in the retina: measurements of PO2 with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O2 concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO2 in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory.

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“…This corroborates with the argument that tissue pO 2 change is linearly correlated with the BOLD response. However, if the baseline tissue pO 2 is 12.8 mmHg (Padnick et al, 1999), a change in pO 2 will be amplified more than the linear change in S v O 2 in the supra-linear regime of the oxygen dissociation curve. When the S v O 2 change is determined from 1.3 mmHg (10% of baseline pO 2 ) and 0.77 mmHg (6% of baseline tissue pO 2 ), for 2 and 30 Hz stimulations, then the relative change in S v O 2 between the low frequency and high frequency responses is about 96% of the relative tissue pO 2 change.…”

Section: Discussionmentioning

confidence: 99%

BOLD responses to different temporal frequency stimuli in the lateral geniculate nucleus and visual cortex: Insights into the neural basis of fMRI

2011

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The neural basis of the blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) remains largely unknown after decades of research. To investigate this issue, the unique property of the temporal frequency tuning that could separate neural input and output in the primary visual cortex was used as a model. During moving grating stimuli of 1, 2, 10 and 20 Hz temporal frequencies, we measured 9.4-T BOLD fMRI responses simultaneously in the primary visual cortex of area 17 (A17) and area 18 (A18), and the lateral geniculate nucleus (LGN) of isoflurane-anesthetized cat. Our results showed preferred temporal frequencies of the BOLD responses for A17, A18 and LGN were 3.1 Hz, 4.5 Hz and 6.0 Hz, respectively, which were comparable to the previously reported electrophysiological data. Additionally, the difference of BOLD response onset time between LGN and A17 was 0.5 s, which is 18 times larger than the difference of neural activity onset time between these areas. We then compared the frequency-dependent BOLD fMRI response of A17 with tissue partial pressure of oxygen (pO2) and electrophysiological data of the same animal model reported by Viswanathan and Freeman (Nature Neuroscience, 2007). The BOLD tuning curve resembled the low frequency band (<12 Hz) of local field potential (LFP) tuning curve rather than spiking activity, gamma band (25–90 Hz) of LFP, and tissue pO2 tuning curves, suggesting that the BOLD fMRI signal relates closer to low frequency LFP.

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Oxygenation of the cat primary visual cortex

Cited by 19 publications

References 27 publications

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue

Retinal oxygen: from animals to humans

BOLD responses to different temporal frequency stimuli in the lateral geniculate nucleus and visual cortex: Insights into the neural basis of fMRI

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