scholarly journals Wearable brain imaging with multimodal physiological monitoring

2018 ◽  
Vol 124 (3) ◽  
pp. 564-572 ◽  
Author(s):  
Gary E. Strangman ◽  
Vladimir Ivkovic ◽  
Quan Zhang
Keyword(s):  
Human Performance ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Tissue Imaging ◽  
Central Component ◽  
Physiological Monitoring ◽  
Self Monitoring ◽  
Brain Physiology ◽  
And Performance ◽  
Clinical Conditions

The brain is a central component of cognitive and physical human performance. Measures, including functional brain activation, cerebral perfusion, cerebral oxygenation, evoked electrical responses, and resting hemodynamic and electrical activity are all related to, or can predict, health status or performance decrements. However, measuring brain physiology typically requires large, stationary machines that are not suitable for mobile or self-monitoring. Moreover, when individuals are ambulatory, systemic physiological fluctuations—e.g., in heart rate, blood pressure, skin perfusion, and more—can interfere with noninvasive brain measurements. In efforts to address the physiological monitoring and performance assessment needs for astronauts during spaceflight, we have developed easy-to-use, wearable prototypes, such as NINscan, for near-infrared scanning, which can collect synchronized multimodal physiology data, including hemodynamic deep-tissue imaging (including brain and muscles), electroencephalography, electrocardiography, electromyography, electrooculography, accelerometry, gyroscopy, pressure, respiration, and temperature measurements. Given their self-contained and portable nature, these devices can be deployed in a much broader range of settings—including austere environments—thereby, enabling a wider range of novel medical and research physiology applications. We review these, including high-altitude assessments, self-deployable multimodal e.g., (polysomnographic) recordings in remote or low-resource environments, fluid shifts in variable-gravity, or spaceflight analog environments, intracranial brain motion during high-impact sports, and long-duration monitoring for clinical symptom-capture in various clinical conditions. In addition to further enhancing sensitivity and miniaturization, advanced computational algorithms could help support real-time feedback and alerts regarding performance and health.

Effects of Acceleration-Induced Reductions in Retinal and Cerebral Oxygenation on Human Performance

2021 ◽  
Vol 92 (2) ◽  
pp. 75-82
Author(s):  
Rodney J. Croft ◽  
Roger Kölegård ◽  
Arne Tribukait ◽  
Nigel A. S. Taylor ◽  
Ola Eiken
Keyword(s):  
Working Memory ◽  
Reaction Time ◽  
Visual Perception ◽  
Visual Working Memory ◽  
Human Performance ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Memory Performance ◽  
Memory Task ◽  
Blood Oxygenation

BACKGROUND: Ischemic hypoxia induced by suprathreshold G-force loading can adversely affect vision, cognition, and lead to loss of consciousness (LOC). The purpose of this study was to determine whether reductions in cerebral oxygenation, caused by subthreshold G-forces (up to 4 Gz and of limited durations that do not lead to LOC), would affect visual perception and working memory performance.METHODS: Sixteen subjects performed visual perception and working memory tasks both before and during Gz exposures (1, 2.2, 3, 4 with leg pressurization, 4 with leg and abdomen pressurization) within a human-use centrifuge.RESULTS: As measured using near-infrared spectroscopy, blood oxygenation over medial prefrontal cortex was similar in the 1 and 2.2 Gz conditions, but was reduced to a similar extent in the 3 and 4 Gz conditions. In parallel, visual perception accuracy was reduced in the 3 and 4 Gz conditions, with no difference between the 3 and 4 Gz conditions. No change in reaction time was seen. Conversely, neither accuracy nor reaction time changes were observed for the visual working memory task.DISCUSSION: These results indicate that although visual working memory is not affected, the ability to visually discriminate between stimuli is reduced at G-forces as low as 3 and 4 Gz. This may have important ramifications for pilots who are routinely subjected to such forces.Croft RJ, Klegrd R, Tribukait A, Taylor NAS, Eiken O. Effects of acceleration-induced reductions in retinal and cerebral oxygenation on human performance. Aerosp Med Hum Perform. 2021; 92(2):7582.

scholarly journals New trends in neuromonitoring patients with aneurysmal subarachnoid haemorrhage

2008 ◽  
Vol 55 (2) ◽  
pp. 69-74 ◽  
Author(s):  
M.M. Dostanic ◽  
M.M. Stosic ◽  
B.D. Milakovic ◽  
B.V. Baljozovic ◽  
I.B. Jovanovic ◽  
...  
Keyword(s):  
Subarachnoid Haemorrhage ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Aneurysmal Subarachnoid Haemorrhage ◽  
Subarachnoidal Hemorrhage ◽  
Secondary Insults ◽  
Brain Physiology ◽  
Complex Process ◽  
Venous Oxygen Saturation ◽  
Nervous System Function

Neurointensive care of patients with subarachnoid haemorrhage is based on the theory that clinical outcome is the consequence of the primary haemorrhage and a number of secondary insults in the acute post haemorrhage period. Several neuromonitoring techniques have been introduced or accomplished into clinical practice in the last decade with the purpose of monitoring different but related aspects of brain physiology, such as cerebral blood flow (CBF), pressure within the cranial cavity, metabolism, and oxygenation. The aim of these techniques is to obtain information that can improve knowledge on brain pathophysiology, and especially to detect secondary insults which may cause permanent neurological damage if undetected and untreated in "real time", at the time when they can still be managed. These techniques include intracranial pressure (ICP) measurements, jugular venous oxygen saturation, near-infrared spectroscopy, brain tissue monitoring, and transcranial Doppler. The available devices are limited because they measure a part of complex process indirectly. Expense, technical difficulties, invasiveness, limited spatial or temporal resolution and the lack of sensitivity add to the limitation of any individual monitor. These problems have been partially addressed by the combination of several monitors known as multimodality monitoring. In this review, we describe the most common neuromonitoring methods in patients with subarachnoidal hemorrhage that can assess nervous system function, cerebral haemodynamics and cerebral oxygenation.

Two-Dimensional Near-Infrared and Shortwave Infrared Molecular Aggregates: Taking Kasha’s Model to the Next Dimension

2019 ◽  
Author(s):  
Arundhati Deshmukh ◽  
Danielle Koppel ◽  
Chern Chuang ◽  
Danielle Cadena ◽  
Jianshu Cao ◽  
...  
Keyword(s):  
Near Infrared ◽  
Photophysical Properties ◽  
Satellite Telemetry ◽  
Transition Dipole Moment ◽  
Short Wave ◽  
Tissue Imaging ◽  
Transition Dipole ◽  
Deep Tissue Imaging ◽  
Excitonic States ◽  
Shortwave Infrared

Technologies which utilize near-infrared (700 – 1000 nm) and short-wave infrared (1000 – 2000 nm) electromagnetic radiation have applications in deep-tissue imaging, telecommunications and satellite telemetry due to low scattering and decreased background signal in this spectral region. However, there are few molecular species, which absorb efficiently beyond 1000 nm. Transition dipole moment coupling (e.g. J-aggregation) allows for redshifted excitonic states and provides a pathway to highly absorptive electronic states in the infrared. We present aggregates of two cyanine dyes whose absorption peaks redshift dramatically upon aggregation in water from ~ 800 nm to 1000 nm and 1050 nm with sheet-like morphologies and high molar absorptivities (e ~ 10<sup>5 </sup>M<sup>-1</sup>cm<sup>-1</sup>). To describe this phenomenology, we extend Kasha’s model for J- and H-aggregation to describe the excitonic states of <i> 2-dimensional aggregates</i> whose slip is controlled by steric hindrance in the assembled structure. A consequence of the increased dimensionality is the phenomenon of an <i>intermediate </i>“I-aggregate”, one which redshifts yet displays spectral signatures of band-edge dark states akin to an H-aggregate. We distinguish between H-, I- and J-aggregates by showing the relative position of the bright (absorptive) state within the density of states using temperature dependent spectroscopy. Our results can be used to better design chromophores with predictable and tunable aggregation with new photophysical properties.

scholarly journals Real-time observation of tetrapyrrole binding to an engineered bacterial phytochrome

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yusaku Hontani ◽  
Mikhail Baloban ◽  
Francisco Velazquez Escobar ◽  
Swetta A. Jansen ◽  
Daria M. Shcherbakova ◽  
...  
Keyword(s):  
Real Time ◽  
Rational Design ◽  
Near Infrared ◽  
Fluorescent Proteins ◽  
Covalent Bond ◽  
Binding Pocket ◽  
Tissue Imaging ◽  
Covalent Attachment ◽  
Time Resolved

AbstractNear-infrared fluorescent proteins (NIR FPs) engineered from bacterial phytochromes are widely used for structural and functional deep-tissue imaging in vivo. To fluoresce, NIR FPs covalently bind a chromophore, such as biliverdin IXa tetrapyrrole. The efficiency of biliverdin binding directly affects the fluorescence properties, rendering understanding of its molecular mechanism of major importance. miRFP proteins constitute a family of bright monomeric NIR FPs that comprise a Per-ARNT-Sim (PAS) and cGMP-specific phosphodiesterases - Adenylyl cyclases - FhlA (GAF) domain. Here, we structurally analyze biliverdin binding to miRFPs in real time using time-resolved stimulated Raman spectroscopy and quantum mechanics/molecular mechanics (QM/MM) calculations. Biliverdin undergoes isomerization, localization to its binding pocket, and pyrrolenine nitrogen protonation in <1 min, followed by hydrogen bond rearrangement in ~2 min. The covalent attachment to a cysteine in the GAF domain was detected in 4.3 min and 19 min in miRFP670 and its C20A mutant, respectively. In miRFP670, a second C–S covalent bond formation to a cysteine in the PAS domain occurred in 14 min, providing a rigid tetrapyrrole structure with high brightness. Our findings provide insights for the rational design of NIR FPs and a novel method to assess cofactor binding to light-sensitive proteins.

Responsive optical probes for deep-tissue imaging: Photoacoustics and second near-infrared fluorescence

2021 ◽  
Vol 173 ◽  
pp. 141-163
Author(s):  
Fei Ding ◽  
Jing Feng ◽  
Xueli Zhang ◽  
Jielin Sun ◽  
Chunhai Fan ◽  
...  
Keyword(s):  
Near Infrared ◽  
Tissue Imaging ◽  
Deep Tissue ◽  
Optical Probes ◽  
Near Infrared Fluorescence ◽  
Deep Tissue Imaging

The Importance of Oversight and Agency Capacity in Enhancing Performance in Public Service Delivery

2020 ◽  
Author(s):  
Cody A Drolc ◽  
Lael R Keiser
Keyword(s):  
Service Delivery ◽  
Performance Management ◽  
Fixed Effects ◽  
Poor Performance ◽  
Central Component ◽  
State Agencies ◽  
Public Programs ◽  
And Performance ◽  
Fixed Effects Regression ◽  
Social Security Disability

Abstract Government agencies often encounter problems in service delivery when implementing public programs. This undermines effectiveness and raise questions about accountability. A central component of responsiveness and performance management is that agencies correct course when problems are identified. However, public agencies have an uneven record in responding to problems. In this paper we investigate whether, and to what extent, capacity both within the agency and within institutions performing oversight, improves agency responsiveness to poor performance indicators. Using panel data on eligibility determinations in the Social Security Disability program from U.S. state agencies from 1991-2015 and fixed effects regression, we find that indicators of agency and oversight capacity moderate the relationship between poor performance and improvement. Our results suggest that investments in building capacity not only within agencies, but also within elected institutions, are important for successful policy implementation. However, we find evidence that while agency capacity alone can improve responsiveness to poor performance, the effect of oversight capacity on improving performance requires high agency capacity.

Continuous Measurement of Cerebral Oxygenation by Near Infrared Spectroscopy During Induction of Anesthesia

1999 ◽  
Vol 88 (3) ◽  
pp. 554-558 ◽  
Author(s):  
A. Timothy Lovell ◽  
Huw Owen-Reece ◽  
Clare E. Elwell ◽  
Martin Smith ◽  
John C. Goldstone
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Continuous Measurement ◽  
Cerebral Oxygenation
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