scholarly journals Multi-Distance Frequency-Domain Optical Measurements of Coherent Cerebral Hemodynamics

Photonics ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 83 ◽  
Author(s):  
Giles Blaney ◽  
Angelo Sassaroli ◽  
Thao Pham ◽  
Nishanth Krishnamurthy ◽  
Sergio Fantini
Keyword(s):  
Frequency Domain ◽  
Phase Difference ◽  
Near Infrared ◽  
Amplitude Ratio ◽  
Human Subjects ◽  
Optical Measurements ◽  
Photon Density ◽  
Healthy Human ◽  
Non Invasive ◽  
Photon Density Waves

We report non-invasive, bilateral optical measurements on the forehead of five healthy human subjects, of 0.1 Hz oscillatory hemodynamics elicited either by cyclic inflation of pneumatic thigh cuffs, or by paced breathing. Optical intensity and the phase of photon-density waves were collected with frequency-domain near-infrared spectroscopy at seven source-detector distances (11–40 mm). Coherent hemodynamic oscillations are represented by phasors of oxyhemoglobin (O) and deoxyhemoglobin (D) concentrations, and by the vector D/O that represents the amplitude ratio and phase difference of D and O. We found that, on an average, the amplitude ratio (|D/O|) and the phase difference (∠(D/O)) obtained with single-distance intensity at 11–40 mm increase from 0.1° and −330° to 0.2° and −200°, respectively. Single-distance phase and the intensity slope featured a weaker dependence on source-detector separation, and yielded |D/O| and ∠(D/O) values of about 0.5 and −200°, respectively, at distances greater than 20 mm. The key findings are: (1) Single-distance phase and intensity slope are sensitive to deeper tissue compared to single-distance intensity; (2) deeper tissue hemodynamic oscillations, which more closely represent the brain, feature D and O phasors that are consistent with a greater relative flow-to-volume contributions in brain tissue compared to extracerebral, superficial tissue.

scholarly journals Non–invasive measurements of breast tissue optical properties using frequency–domain photon migration

1997 ◽  
Vol 352 (1354) ◽  
pp. 661-668 ◽  
Author(s):  
Bruce J. Tromberg ◽  
Olivier Coquoz ◽  
Joshua B. Fishkin ◽  
Tuan Pham ◽  
Eric R. Anderson ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Breast Tissue ◽  
Haemoglobin Concentration ◽  
Water Concentration ◽  
Wavelength Dependence ◽  
Avalanche Photodiode ◽  
Photon Density ◽  
Photon Migration ◽  
Non Invasive ◽  
Photon Density Waves

A multiwavelength, high bandwidth (1 GHz) frequency–domain photon migration (FDPM) instrument has been developed for quantitative, non–invasive measurements of tissue optical and physiological properties. The instrument produces 300 kHz to 1 GHz photon density waves (PDWs) in optically turbid media using a network analyser, an avalanche photodiode detector and four amplitude–modulated diode lasers (674 nm, 811 nm, 849 nm and 956 nm). The frequency–dependence of PDW phase and amplitude is measured and compared to analytically derived model functions in order to calculate absorption, μ a , and reduced scattering, μ ′ s , parameters. The wavelength–dependence of absorption is used to determine tissue haemoglobin concentration (total, oxy– and deoxy– forms), oxygen saturation and water concentration. We present preliminary results of non–invasive FDPM measurements obtained from normal and tumour–containing human breast tissue. Our data clearly demonstrate that physiological changes caused by the presence of small (about 1 cm diameter) palpable lesions can be detected using a handheld FDPM probe.

scholarly journals Facial Vibrotactile Stimulation Activates the Parasympathetic Nervous System: Study of Salivary Secretion, Heart Rate, Pupillary Reflex, and Functional Near-Infrared Spectroscopy Activity

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Hisao Hiraba ◽  
Motoharu Inoue ◽  
Kanako Gora ◽  
Takako Sato ◽  
Satoshi Nishimura ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Infrared Spectroscopy ◽  
Near Infrared ◽  
Human Subjects ◽  
Vibrotactile Stimulation ◽  
Functional Near Infrared Spectroscopy ◽  
Healthy Human ◽  
Healthy Human Subjects ◽  
Stimulation Of

We previously found that the greatest salivation response in healthy human subjects is produced by facial vibrotactile stimulation of 89 Hz frequency with 1.9 μm amplitude (89 Hz-S), as reported by Hiraba et al. (2012, 20011, and 2008). We assessed relationships between the blood flow to brain via functional near-infrared spectroscopy (fNIRS) in the frontal cortex and autonomic parameters. We used the heart rate (HRV: heart rate variability analysis in RR intervals), pupil reflex, and salivation as parameters, but the interrelation between each parameter and fNIRS measures remains unknown. We were to investigate the relationship in response to established paradigms using simultaneously each parameter-fNIRS recording in healthy human subjects. Analysis of fNIRS was examined by a comparison of various values between before and after various stimuli (89 Hz-S, 114 Hz-S, listen to classic music, and “Ahh” vocalization). We confirmed that vibrotactile stimulation (89 Hz) of the parotid glands led to the greatest salivation, greatest increase in heart rate variability, and the most constricted pupils. Furthermore, there were almost no detectable differences between fNIRS during 89 Hz-S and fNIRS during listening to classical music of fans. Thus, vibrotactile stimulation of 89 Hz seems to evoke parasympathetic activity.

scholarly journals A novel device for non-invasive cerebral perfusion assessment

2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Mirko Tessari ◽  
Anna Maria Malagoni ◽  
Maria Elena Vannini ◽  
Paolo Zamboni
Keyword(s):  
Near Infrared ◽  
Single Photon ◽  
Human Subjects ◽  
Low Cost ◽  
Photon Emission ◽  
Diagnostic Technique ◽  
Brain Perfusion ◽  
Emission Computed Tomography ◽  
Wide Field ◽  
Non Invasive

Currently brain perfusion can be assessed by the means of radio-invasive methods, such as single-photon emission computed tomography and positron emission tomography, or by hightech methods such as magnetic resonance imaging. These methods are known to be very expensive, with long examination time, and finally, cannot be used for assessing brain oxygen distribution in relation to exercise and/or cognition-tests. The near infrared spectroscopy (NIRS) is a non-invasive diagnostic technique. In real time it is capable of measuring tissue oxygenation using portable instrumentation with a relative low cost. We and other groups previously adopted this instrument for investigation of the oxygen consumption in the muscles at rest and during exercise. NIRS can be now used to assess brain perfusion through the intact skull in human subjects by detecting changes in blood hemoglobin concentrations. Changes in perfusion can be related to both arterial and venous problems. This novel equipment features allow for a wide field of innovative applications where portability, wearability, and a small footprint are essential. The present review shows how to use it in relation to exercise protocols of the upper and lower extremities, measured in healthy people and in conditions of arterial and chronic cerebro-spinal venous insufficiency.

Real-time video of brain activation in human subjects using a non-invasive near-infrared technique

2000 ◽  
Author(s):  
Maria Angela Franceschini ◽  
Vlad Toronov ◽  
Mattia E. Filiaci ◽  
Martin P. Wolf ◽  
Antonios Michalos ◽  
...  
Keyword(s):  
Real Time ◽  
Near Infrared ◽  
Human Subjects ◽  
Brain Activation ◽  
Non Invasive

scholarly journals First report of rapid, non-invasive, and reagent-free detection of malaria through the skin of patients with a beam of infrared light

2022 ◽  
Author(s):  
Gabriela Garcia ◽  
Tharanga Kariyawasam ◽  
Anton Lord ◽  
Cristiano Costa ◽  
Lana Chaves ◽  
...  
Keyword(s):  
Machine Learning ◽  
Near Infrared ◽  
Predictive Accuracy ◽  
Human Subjects ◽  
Learning Algorithms ◽  
Machine Learning Algorithms ◽  
Supervised Machine Learning ◽  
Infrared Light ◽  
Non Invasive ◽  
Full Capacity

Abstract We describe the first application of the Near-infrared spectroscopy (NIRS) technique to detect Plasmodium falciparum and P. vivax malaria parasites through the skin of malaria positive and negative human subjects. NIRS is a rapid, non-invasive and reagent free technique which involves rapid interaction of a beam of light with a biological sample to produce diagnostic signatures in seconds. We used a handheld, miniaturized spectrometer to shine NIRS light on the ear, arm and finger of P. falciparum (n=7) and P. vivax (n=20) positive people and malaria negative individuals (n=33) in a malaria endemic setting in Brazil. Supervised machine learning algorithms for predicting the presence of malaria were applied to predict malaria infection status in independent individuals (n=12). Separate machine learning algorithms for differentiating P. falciparum from P. vivax infected subjects were developed using spectra from the arm and ear of P. falciparum and P. vivax (n=108) and the resultant model predicted infection in spectra of their fingers (n=54).NIRS non-invasively detected malaria positive and negative individuals that were excluded from the model with 100% sensitivity, 83% specificity and 92% accuracy (n=12) with spectra collected from the arm. Moreover, NIRS also correctly differentiated P. vivax from P. falciparum positive individuals with a predictive accuracy of 93% (n=54). These findings are promising but further work on a larger scale is needed to address several gaps in knowledge and establish the full capacity of NIRS as a non-invasive diagnostic tool for malaria. It is recommended that the tool is further evaluated in multiple epidemiological and demographic settings where other factors such as age, mixed infection and skin colour can be incorporated into predictive algorithms to produce more robust models for universal diagnosis of malaria.

scholarly journals Early and Contemporary Human Neuroimaging Studies of Serotonergic Psychedelics

2020 ◽  
Author(s):  
Enzo Tagliazucchi
Keyword(s):  
Human Subjects ◽  
Brain Activity ◽  
Neural Correlates ◽  
The Self ◽  
Conscious Awareness ◽  
Altered Consciousness ◽  
Healthy Human ◽  
Non Invasive ◽  
Healthy Human Subjects ◽  
Human Neuroimaging

Serotonergic psychedelics are known to elicit changes in conscious awareness, including perception of the environment and the self, as well as in mood, emotion and different aspects of cognition (Nichols, 2016). The effect of these compounds is complex and resists a straightforward classification that is useful for other drugs, such as “stimulants” or “sedatives”. While the effects of certain psychedelics do have a stimulant dimension, their defining characteristic is the capacity to temporarily induce a state of altered consciousness. Because of this, the study of psychedelics cannot be based only on animal models, since humans are alone in their capacity to explicitly report the contents of their conscious awareness. Psychedelic research with healthy human subjects necessitates techniques for the non-invasive recording of brain activity or its physiological and metabolic correlates. These techniques are referred to as “neuroimaging”, and here we review their application in the study of the neural correlates of altered consciousness induced by serotonergic psychedelics.

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