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The behavioral differentiation of positive emotions has recently been studied in terms of their discrete adaptive functions or appraising profiles. Some preliminary neurophysiological evidences have been found with electroencephalography or autonomic nervous system measurements such as heart rate, skin conductance, etc. However, the brain’s hemodynamic responses to different positive emotions remain largely unknown. In the present study, the functional near-infrared spectroscopy (fNIRS) technique was employed. With this tool, we for the first time reported recognizable discrete positive emotions using fNIRS signals. Thirteen participants watched 30 emotional video clips to elicit 10 typical kinds of positive emotions (joy, gratitude, serenity, interest, hope, pride, amusement, inspiration, awe, and love), and their frontal neural activities were simultaneously recorded with a 24-channel fNIRS system. The multidimensional scaling analysis of participants’ subjective ratings on these 10 positive emotions revealed three distinct clusters, which could be interpreted as “playfulness” for amusement, joy, interest, “encouragement” for awe, gratitude, hope, inspiration, pride, and “harmony” for love, serenity. Hemodynamic responses to these three positive emotion clusters showed distinct patterns, and HbO-based individual-level binary classifications between them achieved an averaged accuracy of 73.79 ± 11.49% (77.56 ± 7.39% for encouragement vs. harmony, 73.29 ± 11.87% for playfulness vs. harmony, 70.51 ± 13.96% for encouragement vs. harmony). Benefited from fNIRS’s high portability, low running cost and the relative robustness against motion and electrical artifacts, our findings provided support for implementing a more fine-grained emotion recognition system with subdivided positive emotion categories.

The behavioral differentiation of positive emotions has recently been studied in terms of their discrete adaptive functions or appraising profiles. Some preliminary neurophysiological evidences have been found with electroencephalography or autonomic nervous system measurements such as heart rate, skin conductance, etc. However, the brain's hemodynamic responses to different positive emotions remain largely unknown. In the present study, the functional near-infrared spectroscopy (fNIRS) technique was employed. With this tool, we for the first time reported recognizable discrete positive emotions using fNIRS signals. Thirteen participants watched 30 emotional video clips to elicit 10 typical kinds of positive emotions (joy, gratitude, serenity, interest, hope, pride, amusement, inspiration, awe, and love), and their frontal neural activities were simultaneously recorded with a 24-channel fNIRS system. The multidimensional scaling analysis of participants' subjective ratings on these 10 positive emotions revealed three distinct clusters, which could be interpreted as "playfulness" for amusement, joy, interest, "encouragement" for awe, gratitude, hope, inspiration, pride, and "harmony" for love, serenity. Hemodynamic responses to these three positive emotion clusters showed distinct patterns, and HbO-based individual-level binary classifications between them achieved an averaged accuracy of 73.79 ± 11.49% (77.56 ± 7.39% for encouragement vs. harmony, 73.29 ± 11.87% for playfulness vs. harmony, 70.51 ± 13.96% for encouragement vs. harmony). Benefited from fNIRS's high portability, low running cost and the relative robustness against motion and electrical artifacts, our findings provided support for implementing a more fine-grained emotion recognition system with subdivided positive emotion categories. [ABSTRACT FROM AUTHOR]

Abstract: High field (≥7 T) MRI studies based on signal phase have been used to improve visualization of the fine structure of the brain, most notably the major white matter fiber bundles, the gray–white matter subdivision, and the laminar cortical architecture. The observed contrast has been attributed in part to local variations in magnetic susceptibility arising from iron in storage proteins and tissue lipid. Another contribution could come from the paramagnetic blood constituent deoxy-hemoglobin, the tissue concentration of which may vary through local variations in vascular density. To investigate this possibility, we examined phase contrast between gray and white matter in rats after intravenous administration of a superparamagnetic contrast agent at various dosages. At the maximum dosage (3 mg Fe/kg), which resulted in an estimated paramagnetic susceptibility shift 4–8 times larger than deoxy-hemoglobin, we observed a negligible increase in phase contrast between gray and white matter. This result suggests that endogenous deoxy-hemoglobin has no significant contribution to phase contrast between gray and white matter. [Copyright &y& Elsevier]

Abstract: With the aim of evaluating the relative performance of hemodynamic contrasts for mapping brain activity, the spatio-temporal response of oxy-, deoxy-, and total-hemoglobin concentrations were imaged with diffuse optical tomography during electrical stimulation of the rat somatosensory cortex. For both 6-s and 30-s stimulus durations, total hemoglobin images provided smaller activation areas than oxy- or deoxy-hemoglobin images. In addition, analysis of regions of interest near the sagittal sinus vein show significantly greater contrast in both oxy- and deoxy-relative to total hemoglobin, suggesting that oximetric contrasts have larger draining vein contributions compared to total hemoglobin contrasts under the given stimulus conditions. These results indicate that total hemoglobin and cerebral blood volume may have advantages as hemodynamic mapping contrasts, particularly for large amplitude, longer duration stimulus paradigms. [Copyright &y& Elsevier]

Objective Near-infrared spectroscopy (NIRS) is a non-invasive method for investigating activation of the human cortex. The applicability of NIRS to the olfactory cortex was investigated. Material and Methods The relative oxy- and deoxy-hemoglobin levels of the orbito-frontal cortex during olfactory stimulation in healthy subjects were measured using NIRS. Results When perfumed strips containing the odorants β-phenyl ethyl alcohol, iso-valeric acid and γ-undecalactone were presented, the oxy-hemoglobin level increased but the deoxy-hemoglobin level did not change. The increase in the oxy-hemoglobin level was observed bilaterally. A placebo perfumed strip did not elicit a change in the hemoglobin level. It was also observed that the odorant intensity affected the oxy-hemoglobin level. Although the orbito-frontal cortices seemed to be activated bilaterally during olfaction, the right cortex was activated to a greater extent than the left. Conclusion NIRS appears to be an adequate method for investigating the human olfactory cortex. [ABSTRACT FROM AUTHOR]

A new four-wavelength optical imager has been developed for the evaluation of various vascular diseases. Four-wavelength optical intensity images are transformed to an oxygenation mapping, which further provide maps of rapid changes in hemoglobin distribution in human skin related with peripheral blood flow. This paper presents the configuration of the system and lest measurements for tool disease. Forty-nine volunteers look part in our measurements with an occlusion lest of their legs. Sonic differences were observed in oxygenation change between healthy volunteers and patients, and arteriosclerosis obliterate (ASO) patients and healthy volunteers were clearly distinguishable. [ABSTRACT FROM AUTHOR]

A multi-spectral imaging system is evaluated for mapping melanin density, total-hemoglobin density, and oxygen saturation in human skin. In this system, the distribution of pigments in human skin is estimated and displayed from digital video signals using three pre-computed "look-Lip" tables for color conversions. The accuracy of the system is analyzed based on computer simulation by changing the number of bands, quantization levels of the camera system and dimensions of approximation for spectral reflectance. The optimal system is examined based on the results of computer simulation. [ABSTRACT FROM AUTHOR]

Telemedicine (TM) can revolutionize the impact of diabetic wound care management, along with tools for remote patient monitoring (RPM). There are no low-cost mobile RPM devices for TM technology to provide comprehensive (visual and physiological) clinical assessments. Here, a novel low-cost smartphone-based optical imaging device has been developed to provide physiological measurements of tissues in terms of hemoglobin concentration maps. The device (SmartPhone Oxygenation Tool—SPOT) constitutes an add-on optical module, a smartphone, and a custom app to automate data acquisition while syncing a multi-wavelength near-infrared light-emitting diode (LED) light source (690, 810, 830 nm). The optimal imaging conditions of the SPOT device were determined from signal-to-noise maps. A standard vascular occlusion test was performed in three control subjects to observe changes in hemoglobin concentration maps between rest, occlusion, and release time points on the dorsal of the hand. Hemoglobin concentration maps were compared with and without applying an image de-noising algorithm, single value decomposition. Statistical analysis demonstrated that the hemoglobin concentrations changed significantly across the three-time stamps. Ongoing efforts are in imaging diabetic foot ulcers using the SPOT device to assess its potential as a smart health device for physiological monitoring of wounds remotely. [ABSTRACT FROM AUTHOR]

In fields using functional near-infrared spectroscopy (fNIRS), there is a need for an easy-to-understand method that allows visual presentation and rapid analysis of data and test results. This preliminary study examined whether deep learning (DL) could be applied to the analysis of fNIRS-derived brain activity data. To create a visual presentation of the data, an imaging program was developed for the analysis of hemoglobin (Hb) data from the prefrontal cortex in healthy volunteers, obtained by fNIRS before and after tooth clenching. Three types of imaging data were prepared: oxygenated hemoglobin (oxy-Hb) data, deoxygenated hemoglobin (deoxy-Hb) data, and mixed data (using both oxy-Hb and deoxy-Hb data). To differentiate between rest and tooth clenching, a cross-validation test using the image data for DL and a convolutional neural network was performed. The network identification rate using Hb imaging data was relatively high (80‒90%). These results demonstrated that a method using DL for the assessment of fNIRS imaging data may provide a useful analysis system. [ABSTRACT FROM AUTHOR]

Background: Cerebral perfusion pressure (CPP) calculated by mean arterial pressure (MAP) minus intracranial pressure (ICP) is related to blood flow into the brain and reflects cerebral ischemia and oxygenation indirectly. Near-infrared spectroscopy (NIRS) can assess cerebral ischemia and hypoxia non-invasively and has been widely used in neuroscience. However, the correlation between CPP and NIRS, and its potential application in traumatic brain injury, has seldom been investigated., Methods: We used a novel wireless NIRS system and commercial ICP and MAP devices to assess the trauma to rat brains using different impact intensity. The relationship between CPP and NIRS parameters with increasing impact strength were investigated., Results: The results showed that changes in CPP (∆CPP), oxy-hemoglobin {∆[HbO 2 ]}, total-hemoglobin {∆[HbT]}, and deoxy-hemoglobin were inversely proportional to the increase in impact intensity, and the correlations between ∆CPP, NIRS parameters {∆[HbO 2 ], and ∆[HbT]} were significant., Conclusions: The NIRS system can assess cerebral ischemia and oxygenation non-invasively and changes of HbO 2 and HbT may be used as reference parameters to assess the level of CPP in an animal model of traumatic brain injury., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/qims-20-777). The authors have no conflicts of interest to declare., (2021 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

Assessing neuronal activity by non-invasive functional brain imaging techniques which are based on the hemodynamic response depends totally on the physiological cascade of metabolism and blood flow. At present, functional brain imaging with near infrared spectroscopy (NIRS) or BOLD-fMRI is widely used in cognitive neuroscience in healthy subjects where neurovascular coupling and cerebrovascular reactivity can be assumed to be intact. Local activation studies as well as studies investigating functional connectivity between brain regions of the resting brain provide a rapidly increasing body of knowledge on brain function in humans and animals. Furthermore, functional NIRS and MRI techniques are increasingly being used in patients with severe brain diseases and this use might gain more and more importance for establishing their use in the clinical routine. However, more and more experimental evidence shows that changes in baseline physiological parameters, pharmacological interventions, or disease-related vascular changes may significantly alter the normal response of blood flow and blood oxygenation and thus may lead to misinterpretation of neuronal activity. In this article we present examples of recent experimental findings on pathophysiological changes of neurovascular coupling parameters in animals and discuss their potential implications for functional imaging based on hemodynamic signals such as fNIRS or BOLD-fMRI. To enable correct interpretation of neuronal activity by vascular signals, future research needs to deepen our understanding of the basic mechanisms of neurovascular coupling and the specific characteristics of disturbed neurovascular coupling in the diseased brain.