scholarly journals Mapping oxygen concentration in the awake mouse brain

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Declan G Lyons ◽  
Alexandre Parpaleix ◽  
Morgane Roche ◽  
Serge Charpak
Keyword(s):  
Oxygen Concentration ◽  
Brain Function ◽  
Brain Metabolism ◽  
Tissue Oxygenation ◽  
Physiological Conditions ◽  
Non Invasive ◽  
Isoflurane Anesthesia ◽  
Glomerular Layer ◽  
Physiological Values ◽  
Individual Erythrocytes

Although critical for brain function, the physiological values of cerebral oxygen concentration have remained elusive because high-resolution measurements have only been performed during anesthesia, which affects two major parameters modulating tissue oxygenation: neuronal activity and blood flow. Using measurements of capillary erythrocyte-associated transients, fluctuations of oxygen partial pressure (Po2) associated with individual erythrocytes, to infer Po2 in the nearby neuropil, we report the first non-invasive micron-scale mapping of cerebral Po2 in awake, resting mice. Interstitial Po2 has similar values in the olfactory bulb glomerular layer and the somatosensory cortex, whereas there are large capillary hematocrit and erythrocyte flux differences. Awake tissue Po2 is about half that under isoflurane anesthesia, and within the cortex, vascular and interstitial Po2 values display layer-specific differences which dramatically contrast with those recorded under anesthesia. Our findings emphasize the importance of measuring energy parameters non-invasively in physiological conditions to precisely quantify and model brain metabolism.

scholarly journals Auditory localization should be considered as a sign of minimally conscious state based on multimodal findings

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Manon Carrière ◽  
Helena Cassol ◽  
Charlène Aubinet ◽  
Rajanikant Panda ◽  
Aurore Thibaut ◽  
...  
Keyword(s):  
Brain Function ◽  
Brain Metabolism ◽  
Survival Rates ◽  
Minimally Conscious State ◽  
Conscious State ◽  
Auditory Localization ◽  
Positron Emission ◽  
Level Of Consciousness ◽  
Minimally Conscious

Abstract Auditory localization (i.e. turning the head and/or the eyes towards an auditory stimulus) is often part of the clinical evaluation of patients recovering from coma. The objective of this study is to determine whether auditory localization could be considered as a new sign of minimally conscious state, using a multimodal approach. The presence of auditory localization and the clinical outcome at 2 years of follow-up were evaluated in 186 patients with severe brain injury, including 64 with unresponsive wakefulness syndrome, 28 in minimally conscious state minus, 71 in minimally conscious state plus and 23 who emerged from the minimally conscious state. Brain metabolism, functional connectivity and graph theory measures were investigated by means of 18F-fluorodeoxyglucose positron emission tomography, functional MRI and high-density electroencephalography in two subgroups of unresponsive patients, with and without auditory localization. These two subgroups were also compared to a subgroup of patients in minimally conscious state minus. Auditory localization was observed in 13% of unresponsive patients, 46% of patients in minimally conscious state minus, 62% of patients in minimally conscious state plus and 78% of patients who emerged from the minimally conscious state. The probability to observe an auditory localization increased along with the level of consciousness, and the presence of auditory localization could predict the level of consciousness. Patients with auditory localization had higher survival rates (at 2-year follow-up) than those without localization. Differences in brain function were found between unresponsive patients with and without auditory localization. Higher connectivity in unresponsive patients with auditory localization was measured between the fronto-parietal network and secondary visual areas, and in the alpha band electroencephalography network. Moreover, patients in minimally conscious state minus significantly differed from unresponsive patients without auditory localization in terms of brain metabolism and alpha network centrality, whereas no difference was found with unresponsive patients who presented auditory localization. Our multimodal findings suggest differences in brain function between unresponsive patients with and without auditory localization, which support our hypothesis that auditory localization should be considered as a new sign of minimally conscious state. Unresponsive patients showing auditory localization should therefore no longer be considered unresponsive but minimally conscious. This would have crucial consequences on these patients’ lives as it would directly impact the therapeutic orientation or end-of-life decisions usually taken based on the diagnosis.

scholarly journals The brain timewise: how timing shapes and supports brain function

2015 ◽  
Vol 370 (1668) ◽  
pp. 20140170 ◽  
Author(s):  
Riitta Hari ◽  
Lauri Parkkonen
Keyword(s):  
Human Brain ◽  
Brain Imaging ◽  
Brain Function ◽  
Temporal Dynamics ◽  
Generative Models ◽  
Network Activity ◽  
Brain Diseases ◽  
Specific Information ◽  
Non Invasive ◽  
The Brain

We discuss the importance of timing in brain function: how temporal dynamics of the world has left its traces in the brain during evolution and how we can monitor the dynamics of the human brain with non-invasive measurements. Accurate timing is important for the interplay of neurons, neuronal circuitries, brain areas and human individuals. In the human brain, multiple temporal integration windows are hierarchically organized, with temporal scales ranging from microseconds to tens and hundreds of milliseconds for perceptual, motor and cognitive functions, and up to minutes, hours and even months for hormonal and mood changes. Accurate timing is impaired in several brain diseases. From the current repertoire of non-invasive brain imaging methods, only magnetoencephalography (MEG) and scalp electroencephalography (EEG) provide millisecond time-resolution; our focus in this paper is on MEG. Since the introduction of high-density whole-scalp MEG/EEG coverage in the 1990s, the instrumentation has not changed drastically; yet, novel data analyses are advancing the field rapidly by shifting the focus from the mere pinpointing of activity hotspots to seeking stimulus- or task-specific information and to characterizing functional networks. During the next decades, we can expect increased spatial resolution and accuracy of the time-resolved brain imaging and better understanding of brain function, especially its temporal constraints, with the development of novel instrumentation and finer-grained, physiologically inspired generative models of local and network activity. Merging both spatial and temporal information with increasing accuracy and carrying out recordings in naturalistic conditions, including social interaction, will bring much new information about human brain function.

Measurement of Peripheral Venous Oxygen Saturation in the Leg Using Near-Infrared Spectroscopy

1997 ◽  
Vol 12 (3) ◽  
pp. 96-99 ◽  
Author(s):  
D. Wertheim ◽  
R. Salaman ◽  
J. Melhuish ◽  
R. Williams ◽  
I. Lane ◽  
...  
Keyword(s):  
Near Infrared ◽  
Tissue Oxygenation ◽  
Venous Occlusion ◽  
Lower Leg ◽  
Non Invasive ◽  
Short Period ◽  
Venous Oxygen Saturation ◽  
Invasive Method ◽  
Healing Of Wounds ◽  
Total Haemoglobin

Background: It has been suggested that poor healing of wounds may be associated with reduced tissue oxygenation. A non-invasive method of assessing peripheral venous oxygenation has been investigated. Method: Changes in oxyhaemoglobin (O2Hb), deoxyhaemoglobin (HHb), oxidized cytochrome aa3 (cyt aa3) and total haemoglobin (tHb) were monitored in the left lower leg of seven healthy volunteers. A short period of venous occlusion was achieved by rapidly inflating a sphygmomanometer cuff placed around the leg to 60 mmHg. The changes in O2Hb and tHb, with respect to the baseline readings, were evaluated. PSvO2 was calculated from (ΔO2Hb/ΔtHb) × 100%. Results: From 17 sets of readings on the seven volunteers the median PSvO2 calculated was 64% (range 50–86%). Conclusion: This method appears to be a simple means of evaluating PSvO2. A change in cyt aa3 was often seen associated with the venous occlusion.

scholarly journals Brain–Computer Interfacing Using Functional Near-Infrared Spectroscopy (fNIRS)

Biosensors ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 389
Author(s):  
Kogulan Paulmurugan ◽  
Vimalan Vijayaragavan ◽  
Sayantan Ghosh ◽  
Parasuraman Padmanabhan ◽  
Balázs Gulyás
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Brain Function ◽  
Near Infrared ◽  
Functional Near Infrared Spectroscopy ◽  
Non Invasive ◽  
Neuron Function ◽  
Brain Computer Interfacing ◽  
The Brain ◽  
Computer Interfacing

Functional Near-Infrared Spectroscopy (fNIRS) is a wearable optical spectroscopy system originally developed for continuous and non-invasive monitoring of brain function by measuring blood oxygen concentration. Recent advancements in brain–computer interfacing allow us to control the neuron function of the brain by combining it with fNIRS to regulate cognitive function. In this review manuscript, we provide information regarding current advancement in fNIRS and how it provides advantages in developing brain–computer interfacing to enable neuron function. We also briefly discuss about how we can use this technology for further applications.

scholarly journals Development of Bio-Functionalized, Raman Responsive, and Potentially Excretable Gold Nanoclusters

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2181
Author(s):  
Ryan D. Mellor ◽  
Andreas G. Schätzlein ◽  
Ijeoma F. Uchegbu
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Ethylene Glycol ◽  
Gold Nanoclusters ◽  
Physiological Conditions ◽  
Non Invasive ◽  
In Vivo Detection ◽  
Raman Response ◽  
Octadecyl Amine

Gold nanoparticles (AuNPs) are used experimentally for non-invasive in vivo Raman monitoring because they show a strong absorbance in the phototherapeutic window (650–850 nm), a feature that is accompanied by a particle size in excess of 100 nm. However, these AuNPs cannot be used clinically because they are likely to persist in mammalian systems and resist excretion. In this work, clustered ultrasmall (sub-5 nm) AuNP constructs for in vivo Raman diagnostic monitoring, which are also suitable for mammalian excretion, were synthesized and characterized. Sub-5 nm octadecyl amine (ODA)-coated AuNPs were clustered using a labile dithiol linker: ethylene glycol bis-mercaptoacetate (EGBMA). Upon clustering via a controlled reaction and finally coating with a polymeric amphiphile, a strong absorbance in the phototherapeutic window was demonstrated, thus showing the potential suitability of the construct for non-invasive in vivo detection and monitoring. The clusters, when labelled with a biphenyl-4-thiol (BPT) Raman tag, were shown to elicit a specific Raman response in plasma and to disaggregate back to sub-5 nm particles under physiological conditions (37 °C, 0.8 mM glutathione, pH 7.4). These data demonstrate the potential of these new AuNP clusters (Raman NanoTheranostics—RaNT) for in vivo applications while being in the excretable size window.

MEG/EEG in the Study of Brain Function

2017 ◽  
pp. 304-310
Author(s):  
Riitta Hari ◽  
Aina Puce
Keyword(s):  
Human Brain ◽  
Brain Function ◽  
Social Neuroscience ◽  
Future Research ◽  
Noninvasive Methods ◽  
Advantages And Disadvantages ◽  
Non Invasive ◽  
Combined Use ◽  
Eeg Recordings ◽  
Two Sides

This chapter summarizes some relative advantages and disadvantages of MEG and EEG, most of which have been previously elaborated. MEG and EEG are the two sides of the same coin and provide complementary information about the human brain’s neurodynamics. The combined use of MEG or EEG together and with other noninvasive methods used to study human brain function is advocated to be important for future research in systems and cognitive/social neuroscience. This chapter also examines combined use and interpretation of MEG/EEG with MRI/fMRI, and performing EEG recordings during non-invasive brain stimulation.

scholarly journals Neuromodulation Special IssueNon-invasive stimulation of the social brain: the methodological challenges

2020 ◽  
Author(s):  
Tegan Penton ◽  
Caroline Catmur ◽  
Michael J Banissy ◽  
Geoffrey Bird ◽  
Vincent Walsh
Keyword(s):  
Brain Stimulation ◽  
Brain Function ◽  
Social Brain ◽  
Non Invasive ◽  
Social Processing ◽  
The Social ◽  
Social Difficulties ◽  
Lesion Studies ◽  
Reliable Interpretation ◽  
Stimulation Of

Abstract Use of non-invasive brain stimulation methods (NIBS) has become a common approach to study social processing in addition to behavioural, imaging and lesion studies. However, research using NIBS to investigate social processing faces challenges. Overcoming these is important to allow valid and reliable interpretation of findings in neurotypical cohorts, but also to allow us to tailor NIBS protocols to atypical groups with social difficulties. In this review, we consider the utility of brain stimulation as a technique to study and modulate social processing. We also discuss challenges that face researchers using NIBS to study social processing in neurotypical adults with a view to highlighting potential solutions. Finally, we discuss additional challenges that face researchers using NIBS to study and modulate social processing in atypical groups. These are important to consider given that NIBS protocols are rarely tailored to atypical groups before use. Instead, many rely on protocols designed for neurotypical adults despite differences in brain function that are likely to impact response to NIBS.

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