scholarly journals Microscopic Quantification of Oxygen Consumption across Cortical Layers

2021 ◽  
Author(s):  
Philipp Mächler ◽  
Natalie Fomin-Thunemann ◽  
Martin Thunemann ◽  
Marte Julie Sætra ◽  
Michèle Desjardins ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Cytochrome Oxidase ◽  
Blood Oxygen Level Dependent ◽  
Cortical Layer ◽  
Cortical Layers ◽  
Inner Mitochondrial Membrane ◽  
Blood Oxygen Level ◽  
Phosphorescence Lifetime ◽  
Cellular Density ◽  
Cortical Laminar

The cerebral cortex is organized in cortical layers that differ in their cellular density, composition, and wiring. Cortical laminar architecture is also readily revealed by staining for cytochrome oxidase – the last enzyme in the respiratory electron transport chain located in the inner mitochondrial membrane. It has been hypothesized that a high-density band of cytochrome oxidase in cortical layer IV reflects higher oxygen consumption under baseline (unstimulated) conditions. Here, we tested the above hypothesis using direct measurements of the partial pressure of O 2 (pO 2 ) in cortical tissue by means of 2-photon phosphorescence lifetime microscopy (2PLM). We revisited our previously developed method for extraction of the cerebral metabolic rate of O 2 (CMRO 2 ) based on 2-photon pO 2 measurements around diving arterioles and applied this method to estimate baseline CMRO 2 in awake mice across cortical layers. To our surprise, our results revealed a decrease in baseline CMRO 2 from layer I to layer IV . This decrease of CMRO 2 with cortical depth was paralleled by an increase in tissue oxygenation. Higher baseline oxygenation and cytochrome density in layer IV may serve as an O 2 reserve during surges of neuronal activity or certain metabolically active brain states rather than baseline energy needs. Our study provides the first quantification of microscopically resolved CMRO 2 across cortical layers as a step towards informed interpretation and modeling of cortical-layer-specific Blood Oxygen Level Dependent (BOLD) fMRI signals.

scholarly journals The many layers of BOLD. On the contribution of different vascular compartments to laminar fMRI.

2021 ◽  
Author(s):  
Wouter Schellekens ◽  
Alex A Bhogal ◽  
Emiel C.A. Roefs ◽  
Mario G Baez-Yanez ◽  
Jeroen C.W. Siero ◽  
...  
Keyword(s):  
Spin Echo ◽  
Blood Oxygen Level Dependent ◽  
Relative Difference ◽  
Cerebrovascular Reactivity ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Cortical Layers ◽  
Blood Oxygen Level ◽  
Ultra High Field ◽  
The Many

Ultra-high field functional Magnetic Resonance Imaging (fMRI) offers the spatial resolution to measure neural activity at the scale of cortical layers. Most fMRI studies make use of the Blood-Oxygen-Level Dependent (BOLD) signal, arising from a complex interaction of changes in cerebral blood flow (CBF) and volume (CBV), and venous oxygenation. However, along with cyto- and myeloarchitectural changes across cortical depth, laminar fMRI is confronted with additional confounds related to vascularization differences that exist across cortical depth. In the current study, we quantify how the non-uniform distribution of macro- and micro-vascular compartments, as measured with Gradient-Echo (GE) and Spin-Echo (SE) scan sequences, respectively, affect laminar BOLD fMRI responses following evoked hypercapnic and hyperoxic breathing conditions. We find that both macro- and micro-vascular compartments are capable of comparable theoretical maximum signal intensities, as represented by the M-scaling parameter. However, the capacity for vessel dilation, as reflected by the cerebrovascular reactivity (CVR), is approximately three times larger for the macro- compared to the micro-vasculature at superficial layers. Finally, there is roughly a 35% difference in CBV estimates between the macro- and micro-vascular compartments, although this relative difference is approximately uniform across cortical depth.

scholarly journals Pathway-Specific Variations in Neurovascular and Neurometabolic Coupling in Rat Primary Somatosensory Cortex

2009 ◽  
Vol 29 (5) ◽  
pp. 976-986 ◽  
Author(s):  
Pia Enager ◽  
Henning Piilgaard ◽  
Nikolas Offenhauser ◽  
Ara Kocharyan ◽  
Priscilla Fernandes ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Cortical Area ◽  
Functional Neuroimaging ◽  
Brain Area ◽  
Pyramidal Cells ◽  
Blood Oxygen Level Dependent ◽  
Synaptic Activity ◽  
Inhibitory Interneurons ◽  
Blood Oxygen Level ◽  
Evoked Activity

Functional neuroimaging signals are generated, in part, by increases in cerebral blood flow (CBF) evoked by mediators, such as nitric oxide and arachidonic acid derivatives that are released in response to increased neurotransmission. However, it is unknown whether the vascular and metabolic responses within a given brain area differ when local neuronal activity is evoked by an activity in the distinct neuronal networks. In this study we assessed, for the first time, the differences in neuronal responses and changes in CBF and oxygen consumption that are evoked after the activation of two different inputs to a single cortical area. We show that, for a given level of glutamatergic synaptic activity, corticocortical and thalamocortical inputs evoked activity in pyramidal cells and different classes of interneurons, and produced different changes in oxygen consumption and CBF. Furthermore, increases in stimulation intensities either turned off or activated additional classes of inhibitory interneurons immunoreactive for different vasoactive molecules, which may contribute to increases in CBF. Our data imply that for a given cortical area, the amplitude of vascular signals will depend critically on the type of input, and that a positive blood oxygen level-dependent (BOLD) signal may be a consequence of the activation of both pyramidal cells and inhibitory interneurons.

Optical measurement of microvascular oxygenation and blood flow responses in awake mouse cortex during functional activation

2020 ◽  
pp. 0271678X2092801 ◽  
Author(s):  
İkbal Şencan ◽  
Tatiana Esipova ◽  
Kıvılcım Kılıç ◽  
Baoqiang Li ◽  
Michèle Desjardins ◽  
...  
Keyword(s):  
Optical Measurement ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Blood Oxygen Level ◽  
Phosphorescence Lifetime ◽  
Two Photon ◽  
Mouse Cortex ◽  
Health And Disease ◽  
Initial Dip ◽  
Induced Changes

The cerebral cortex has a number of conserved morphological and functional characteristics across brain regions and species. Among them, the laminar differences in microvascular density and mitochondrial cytochrome c oxidase staining suggest potential laminar variability in the baseline O2 metabolism and/or laminar variability in both O2 demand and hemodynamic response. Here, we investigate the laminar profile of stimulus-induced intravascular partial pressure of O2 (pO2) transients to stimulus-induced neuronal activation in fully awake mice using two-photon phosphorescence lifetime microscopy. Our results demonstrate that stimulus-induced changes in intravascular pO2 are conserved across cortical layers I–IV, suggesting a tightly controlled neurovascular response to provide adequate O2 supply across cortical depth. In addition, we observed a larger change in venular O2 saturation (ΔsO2) compared to arterioles, a gradual increase in venular ΔsO2 response towards the cortical surface, and absence of the intravascular “initial dip” previously reported under anesthesia. This study paves the way for quantification of layer-specific cerebral O2 metabolic responses, facilitating investigation of brain energetics in health and disease and informed interpretation of laminar blood oxygen level dependent functional magnetic resonance imaging signals.

scholarly journals Evaluation of Renal Tissue Oxygenation Using Blood Oxygen Level-Dependent Magnetic Resonance Imaging in Chronic Kidney Disease

2021 ◽  
pp. 1-11
Author(s):  
Fen Chen ◽  
Han Yan ◽  
Fan Yang ◽  
Li Cheng ◽  
Siwei Zhang ◽  
...  
Keyword(s):  
Renal Function ◽  
Tissue Oxygenation ◽  
Blood Oxygen Level Dependent ◽  
Renal Tissue ◽  
Selection Method ◽  
Resonance Imaging ◽  
Blood Oxygen Level ◽  
Bold Mri ◽  
Function Group ◽  
Renal Function Group

<b><i>Background:</i></b> Blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) has been widely used to assess renal oxygenation changes in different kidney diseases in recent years. This study was designed to evaluate and compare renal tissue oxygenation using 2 BOLD-MRI analysis methods, namely, the regional and whole-kidney region of interest (ROI) selection methods. <b><i>Methods:</i></b> The study ended up with 10 healthy controls and 40 chronic kidney disease (CKD) patients without dialysis. Their renal BOLD-MRI data were analyzed using whole-kidney ROI selection method and compared with regional ROI selection method. <b><i>Results:</i></b> We found the cortical, medullary, and whole-kidney R2* values were significantly higher in CKD patients than those in controls. Compared with the regional ROI selection method, the whole-kidney ROI selection method yielded higher cortical R2* values in both controls and CKD patients. The whole-kidney R2* values of deteriorating renal function group were significantly higher than those in stable renal function group. <b><i>Conclusions:</i></b> Cortical and medullary oxygenation was decreased significantly in CKD patients compared with the healthy controls, particularly in the medulla. The whole-kidney R2* values were positively correlated with kidney function and inversely correlated with the estimated glomerular filtration rate and effective renal plasma flow. Whole-Kidney R2* value might effectively predict the progression of renal function in patients with CKD.

Visual Cortex Alterations in Early and Late Blind Subjects During Tactile Perception

Perception ◽  
2021 ◽  
Vol 50 (3) ◽  
pp. 249-265
Author(s):  
A. Ankeeta ◽  
S. Senthil Kumaran ◽  
Rohit Saxena ◽  
Sada N. Dwivedi ◽  
Naranamangalam R. Jagannathan
Keyword(s):  
Visual Cortex ◽  
Children And Adolescents ◽  
Age Of Onset ◽  
Human Subjects ◽  
Functional Results ◽  
Blood Oxygen Level Dependent ◽  
Tactile Perception ◽  
Blood Oxygen Level ◽  
Sensory Motor ◽  
Post Hoc

Involvement of visual cortex varies during tactile perception tasks in early blind (EB) and late blind (LB) human subjects. This study explored differences in sensory motor networks associated with tactile task in EB and LB subjects and between children and adolescents. A total of 40 EB subjects, 40 LB subjects, and 30 sighted controls were recruited in two subgroups: children (6–12 years) and adolescents (13–19 years). Data were acquired using a 3T MR scanner. Analyses of blood oxygen level dependent (BOLD), functional connectivity (FC), correlation, and post hoc test for multiple comparisons were carried out. Difference in BOLD activity was observed in EB and LB groups in visual cortex during tactile perception, with increased FC of visual with dorsal attention and sensory motor networks in EB. EB adolescents exhibited increased connectivity with default mode and salience networks when compared with LB. Functional results correlated with duration of training, suggestive of better performance in EB. Alteration in sensory and visual networks in EB and LB correlated with duration of tactile training. Age of onset of blindness has an effect in cross-modal reorganization of visual cortex in EB and multimodal in LB in children and adolescents.

scholarly journals Brain reactivity using fMRI to insomnia stimuli in insomnia patients with discrepancy between subjective and objective sleep

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Young-Bo Kim ◽  
Nambeom Kim ◽  
Jae Jun Lee ◽  
Seo-Eun Cho ◽  
Kyoung-Sae Na ◽  
...  
Keyword(s):  
Brain Activity ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Cognitive Distortion ◽  
Sleep Diary ◽  
Bold Signal ◽  
Blood Oxygen Level ◽  
General Anxiety ◽  
Sleep Deficit ◽  
Perception Of Sleep

AbstractSubjective–objective discrepancy of sleep (SODS) might be related to the distorted perception of sleep deficit and hypersensitivity to insomnia-related stimuli. We investigated differences in brain activation to insomnia-related stimuli among insomnia patients with SODS (SODS group), insomnia patients without SODS (NOSODS group), and healthy controls (HC). Participants were evaluated for subjective and objective sleep using sleep diary and polysomnography. Functional magnetic resonance imaging was conducted during the presentation of insomnia-related (Ins), general anxiety-inducing (Gen), and neutral (Neu) stimuli. Brain reactivity to the contrast of Ins vs. Neu and Gen vs. Neu was compared among the SODS (n = 13), NOSODS (n = 15), and HC (n = 16) groups. In the SODS group compared to other groups, brain areas including the left fusiform, bilateral precuneus, right superior frontal gyrus, genu of corpus callosum, and bilateral anterior corona radiata showed significantly increased blood oxygen level dependent (BOLD) signal in the contrast of Ins vs. Neu. There was no brain region with significantly increased BOLD signal in the Gen vs. Neu contrast in the group comparisons. Increased brain activity to insomnia-related stimuli in several brain regions of the SODS group is likely due to these individuals being more sensitive to sleep-related threat and negative cognitive distortion toward insomnia.

Blood oxygen-level dependent functional assessment of cerebrovascular reactivity: Feasibility for intraoperative 3 Tesla MRI

2016 ◽  
Vol 77 (2) ◽  
pp. 806-813 ◽  
Author(s):  
Jorn Fierstra ◽  
Jan-Karl Burkhardt ◽  
Christiaan Hendrik Bas van Niftrik ◽  
Marco Piccirelli ◽  
Athina Pangalu ◽  
...  
Keyword(s):  
Functional Assessment ◽  
Blood Oxygen Level Dependent ◽  
Cerebrovascular Reactivity ◽  
3 Tesla ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
3 Tesla Mri
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