scholarly journals Improved Spatial Resolution of Electroencephalogram Using Tripolar Concentric Ring Electrode Sensors

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Xiang Liu ◽  
Oleksandr Makeyev ◽  
Walter Besio
Keyword(s):  
Spatial Resolution ◽  
Signal To Noise Ratio ◽  
Human Subjects ◽  
Region Of Interest ◽  
Ring Electrode ◽  
Brain Diseases ◽  
Concentric Ring ◽  
Healthy Human ◽  
Good Spatial Resolution ◽  
Visual Evoked

The electroencephalogram (EEG) is broadly used for research of brain activities and diagnosis of brain diseases and disorders. Although EEG provides good temporal resolution of millisecond or less, it does not provide good spatial resolution. There are two main reasons for the poor spatial resolution: the blurring effects of the head volume conductor and poor signal-to-noise ratio. We have developed a tripolar concentric ring electrode (TCRE) Laplacian sensor and now report on computer simulations comparing spatial resolution between conventional EEG disc electrode sensors and TCRE Laplacian sensors. We also performed visual evoked stimulus experiments and acquired visual evoked potentials (VEPs) from healthy human subjects. From the simulations, we found that TCRE Laplacian sensors can provide approximately a tenfold improvement in spatial resolution and pass signals from specific volumes. Placing TCRE sensors near the brain region of interest will allow passage of the wanted signals and rejection of distant interference signals. We were also able to detect VEPs on the scalp surface and show that TCREs separated VEP sources better than conventional disc electrodes.

scholarly journals tACS facilitates flickering driving by boosting steady-state visual evoked potentials

2021 ◽  
Vol 18 (6) ◽  
pp. 066042
Author(s):  
Bingchuan Liu ◽  
Xinyi Yan ◽  
Xiaogang Chen ◽  
Yijun Wang ◽  
Xiaorong Gao
Keyword(s):  
Steady State ◽  
Visual Stimulation ◽  
Signal To Noise Ratio ◽  
Human Subjects ◽  
Brain State ◽  
Healthy Human ◽  
Rhythmic Stimulation ◽  
Before And After ◽  
Transcranial Alternating Current Stimulation ◽  
Visual Evoked

Abstract Objective. There has become of increasing interest in transcranial alternating current stimulation (tACS) since its inception nearly a decade ago. tACS in modulating brain state is an active area of research and has been demonstrated effective in various neuropsychological and clinical domains. In the visual domain, much effort has been dedicated to brain rhythms and rhythmic stimulation, i.e. tACS. However, less is known about the interplay between the rhythmic stimulation and visual stimulation. Approach. Here, we used steady-state visual evoked potential (SSVEP), induced by flickering driving as a widely used technique for frequency-tagging, to investigate the aftereffect of tACS in healthy human subjects. Seven blocks of 64-channel electroencephalogram were recorded before and after the administration of 20min 10Hz tACS, while subjects performed several blocks of SSVEP tasks. We characterized the physiological properties of tACS aftereffect by comparing and validating the temporal, spatial, spatiotemporal and signal-to-noise ratio (SNR) patterns between and within blocks in real tACS and sham tACS. Main results. Our result revealed that tACS boosted the 10Hz SSVEP significantly. Besides, the aftereffect on SSVEP was mitigated with time and lasted up to 5 min. Significance. Our results demonstrate the feasibility of facilitating the flickering driving by external rhythmic stimulation and open a new possibility to alter the brain state in a direction by noninvasive transcranial brain stimulation.

“Clock-scan” protocol for image analysis

2006 ◽  
Vol 291 (5) ◽  
pp. C869-C879 ◽  
Author(s):  
Maxim Dobretsov ◽  
Dmitry Romanovsky
Keyword(s):  
Image Analysis ◽  
Spatial Resolution ◽  
Neuronal Cell ◽  
Region Of Interest ◽  
Dorsal Root Ganglion Neurons ◽  
Protein Markers ◽  
Pixel Intensity ◽  
Good Spatial Resolution ◽  
Ganglion Neurons ◽  
Scan Protocol

Comparative analysis of extra- and intracellular distributions of protein markers in immunohistochemical and immunofluorescent studies relies on techniques of image analysis. Line or region of interest pixel intensity scans are methods routinely used. However, although having good spatial resolution, linear pixel intensity scans fail to produce integral image of the cellular distribution of the label. On the other hand, the regions of interest scans have good integrative capacity but low spatial resolution. In this work, we describe a “clock-scan” protocol that, when applied to convex objects (such as neuronal cell bodies and the majority of cells in culture), combines advantages and circumnavigates limitations of the above-mentioned techniques. The protocol 1) collects multiple radial pixel intensity profiles scanned from the cell center to the periphery, 2) scales these profiles according to the cell radius measured in the direction of the scan, and finally, 3) averages these individual profiles into one integral radial pixel intensity profile. Because of scaling, the mean pixel intensity profiles produced by the clock-scan protocol depend on neither the cell size nor, within reasonable limits, the cell shape. This allows direct comparison or, if required, averaging or subtraction of profiles of different cells. We have successfully tested the clock-scan protocol in experiments with immunostained dorsal root ganglion neurons. In addition, the protocol seems to be equally applicable for studies in a variety of other preparations.

Effects of Two Anticholinergic Drugs on Electroretinograms and Visual Evoked Potentials in Healthy Human Subjects

1990 ◽  
Vol 24 (4) ◽  
pp. 205-209 ◽  
Author(s):  
Peter Bartel ◽  
Marie Blom ◽  
Elna Robinson ◽  
C. van der Meyden ◽  
Klerk Sommers ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Human Subjects ◽  
Anticholinergic Drugs ◽  
Healthy Human ◽  
Healthy Human Subjects ◽  
Visual Evoked

scholarly journals Brain potentials evoked by intraepidermal electrical stimuli reflect the central sensitization of nociceptive pathways

2016 ◽  
Vol 116 (2) ◽  
pp. 286-295 ◽  
Author(s):  
M. Liang ◽  
M. C. Lee ◽  
J. O'Neill ◽  
A. H. Dickenson ◽  
G. D. Iannetti
Keyword(s):  
Central Sensitization ◽  
Signal To Noise Ratio ◽  
Human Subjects ◽  
Secondary Hyperalgesia ◽  
Healthy Human ◽  
Brain Potentials ◽  
Characteristics Analysis ◽  
Increased Sensitivity ◽  
Nociceptive Input ◽  
Clinical Conditions

Central sensitization (CS), the increased sensitivity of the central nervous system to somatosensory inputs, accounts for secondary hyperalgesia, a typical sign of several painful clinical conditions. Brain potentials elicited by mechanical punctate stimulation using flat-tip probes can provide neural correlates of CS, but their signal-to-noise ratio is limited by poor synchronization of the afferent nociceptive input. Additionally, mechanical punctate stimulation does not activate nociceptors exclusively. In contrast, low-intensity intraepidermal electrical stimulation (IES) allows selective activation of type II Aδ-mechano-heat nociceptors (II-AMHs) and elicits reproducible brain potentials. However, it is unclear whether hyperalgesia from IES occurs and coexists with secondary mechanical punctate hyperalgesia, and whether the magnitude of the electroencephalographic (EEG) responses evoked by IES within the hyperalgesic area is increased. To address these questions, we explored the modulation of the psychophysical and EEG responses to IES by intraepidermal injection of capsaicin in healthy human subjects. We obtained three main results. First, the intensity of the sensation elicited by IES was significantly increased in participants who developed robust mechanical punctate hyperalgesia after capsaicin injection (i.e., responders), indicating that hyperalgesia from IES coexists with punctate mechanical hyperalgesia. Second, the N2 peak magnitude of the EEG responses elicited by IES was significantly increased after the intraepidermal injection of capsaicin in responders only. Third, a receiver-operator characteristics analysis showed that the N2 peak amplitude is clearly predictive of the presence of CS. These findings suggest that the EEG responses elicited by IES reflect secondary hyperalgesia and therefore represent an objective correlate of CS.

Quality Assessment of Mobile Cone-beam Computerized Tomography Scanner Made in Thailand: A Phantom Study

2021 ◽  
Vol 104 (12) ◽  
pp. 1937-1946
Keyword(s):  
Computed Tomography ◽  
Spatial Resolution ◽  
Technology Development ◽  
Human Subjects ◽  
Cone Beam ◽  
Geometric Accuracy ◽  
Ct Scanner ◽  
Ct Number ◽  
Good Spatial Resolution ◽  
Noise Production

Background: In 2011, the National Science and Technology Development Agency had successfully developed the first local-made mobile conebeam computed tomography (CBCT) scanner, called MobiiScan. Before a computed tomography (CT) scanner can be used in clinical practice, it must pass a quality assurance process. Objective: To assess the performance of MobiiScan before it can be further evaluated in human subjects. Materials and Methods: Images from scanning of an imaging phantom by MobiiScan were compared to a commercial 64-slice (GE Discovery CT750 HD) and a mobile (Neurologica CereTom) CT scanner, which were used as controls. Spatial resolution, uniformity, noise, accuracy of CT number, and geometric accuracy were examined by three investigators. Results: According to the bone scanning protocol, spatial resolution of the images produced by MobiiScan was comparable to the mobile scanner, but it was less than the 64-slice scanner. In addition, the signal uniformity of MobiiScan was poorer compared to the controls. MobiiScan produced more noise than the mobile and the 64-slice scanners at the 120-kVp mode, but less noise than the 64-slice scanner at the 80-kVp mode. Using the brain protocol, the spatial resolution from the MobiiScan was higher than the mobile scanner, but comparable to the 64-slice scanner. Although the signal uniformity of the MobiiScan was superior compared to the controls, the noise production was more than the controls. At all settings, the MobiiScan gave underrated distances and inaccurate CT numbers. However, it delivered very low radiation doses. Conclusion: MobiiScan had a good spatial resolution and delivered low radiation dose, which suggested that it could be used for bone examination as intended by the creator. However, its noise production and inaccurate CT numbers suggest that MobiiScan should not be used to diagnose soft tissue problems. It is recommended that the hardware and software should be adjusted to provide a better signal uniformity, lower noise level, accurate CT number, and geometric accuracy. Keywords: X-ray computed tomography; Cone-beam computed tomography; Craniofacial abnormalities; Radiologic phantom; MobiiScan

scholarly journals Data-driven analysis of facial thermal responses to an emotional movie reveals consistent stimulus-locked physiological changes

2020 ◽  
Author(s):  
Saurabh Sonkusare ◽  
Michael Breakspear ◽  
Tianji Pang ◽  
Vinh Thai Nguyen ◽  
Sascha Frydman ◽  
...  
Keyword(s):  
Thermal Imaging ◽  
Motion Correction ◽  
Emotional State ◽  
Human Subjects ◽  
Region Of Interest ◽  
Full Potential ◽  
Healthy Human ◽  
Physiological Profile ◽  
Psychophysiological Measures ◽  
Contact Free

AbstractFacial infra-red imaging (IRI) is a contact-free technique complimenting the traditional psychophysiological measures to characterize physiological profile. However, its full potential in affective research is arguably unmet due to the analytical challenges it poses. Here we acquired facial IRI data, facial expressions and traditional physiological recordings (heart rate and skin conductance) from healthy human subjects whilst they viewed a 20-minute-long unedited emotional movie. We present a novel application of motion correction and the results of spatial independent component analysis of the thermal data. Three distinct spatial components are recovered associated with the nose, the cheeks and a respiratory component. We first benchmark this methodology against a traditional region-of-interest based technique. We then show significant correlation of all the physiological responses across subjects, including the thermal signals, suggesting common dynamic shifts in emotional state induced by the movie. Finally, we show that thermal responses were significantly anti-correlated with the positive emotional content of the movie thus an index of emotionally-driven physiological response. In sum, this study introduces an innovative approach to analyse facial IRI data and highlights the potential of thermal imaging to robustly capture emotion-related changes in ecological contexts.

scholarly journals Noninvasive neuromagnetic single-trial analysis of human neocortical population spikes

2021 ◽  
Vol 118 (11) ◽  
pp. e2017401118
Author(s):  
Gunnar Waterstraat ◽  
Rainer Körber ◽  
Jan-Hendrik Storm ◽  
Gabriel Curio
Keyword(s):  
Signal To Noise Ratio ◽  
Human Subjects ◽  
Low Frequency ◽  
Single Trial ◽  
Significant Trial ◽  
Healthy Human ◽  
Response Latencies ◽  
Time Resolved ◽  
Population Spikes ◽  
Trial Analysis

Neuronal spiking is commonly recorded by invasive sharp microelectrodes, whereas standard noninvasive macroapproaches (e.g., electroencephalography [EEG] and magnetoencephalography [MEG]) predominantly represent mass postsynaptic potentials. A notable exception are low-amplitude high-frequency (∼600 Hz) somatosensory EEG/MEG responses that can represent population spikes when averaged over hundreds of trials to raise the signal-to-noise ratio. Here, a recent leap in MEG technology—featuring a factor 10 reduction in white noise level compared with standard systems—is leveraged to establish an effective single-trial portrayal of evoked cortical population spike bursts in healthy human subjects. This time-resolved approach proved instrumental in revealing a significant trial-to-trial variability of burst amplitudes as well as time-correlated (∼10 s) fluctuations of burst response latencies. Thus, ultralow-noise MEG enables noninvasive single-trial analyses of human cortical population spikes concurrent with low-frequency mass postsynaptic activity and thereby could comprehensively characterize cortical processing, potentially also in diseases not amenable to invasive microelectrode recordings.

scholarly journals Data-driven analysis of facial thermal responses and multimodal physiological consistency among subjects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saurabh Sonkusare ◽  
Michael Breakspear ◽  
Tianji Pang ◽  
Vinh Thai Nguyen ◽  
Sascha Frydman ◽  
...  
Keyword(s):  
Thermal Imaging ◽  
Motion Correction ◽  
Emotional State ◽  
Human Subjects ◽  
Region Of Interest ◽  
Full Potential ◽  
Healthy Human ◽  
Physiological Profile ◽  
Psychophysiological Measures ◽  
Contact Free

AbstractFacial infra-red imaging (IRI) is a contact-free technique complimenting the traditional psychophysiological measures to characterize physiological profile. However, its full potential in affective research is arguably unmet due to the analytical challenges it poses. Here we acquired facial IRI data, facial expressions and traditional physiological recordings (heart rate and skin conductance) from healthy human subjects whilst they viewed a 20-min-long unedited emotional movie. We present a novel application of motion correction and the results of spatial independent component analysis of the thermal data. Three distinct spatial components are recovered associated with the nose, the cheeks and respiration. We first benchmark this methodology against a traditional nose-tip region-of-interest based technique showing an expected similarity of signals extracted by these methods. We then show significant correlation of all the physiological responses across subjects, including the thermal signals, suggesting common dynamic shifts in emotional state induced by the movie. In sum, this study introduces an innovative approach to analyse facial IRI data and highlights the potential of thermal imaging to robustly capture emotion-related changes induced by ecological stimuli.

Minimizing Carry-Over Effects After Treatment Failure and Maximizing Therapeutic Outcome

2014 ◽  
Vol 222 (3) ◽  
pp. 171-178 ◽  
Author(s):  
Mareile Hofmann ◽  
Nathalie Wrobel ◽  
Simon Kessner ◽  
Ulrike Bingel
Keyword(s):  
Treatment Failure ◽  
Human Subjects ◽  
Subsequent Treatment ◽  
Clinical Samples ◽  
Administration Route ◽  
Healthy Human ◽  
Negative Experiences ◽  
Analgesic Treatment ◽  
Balanced Design ◽  
Carry Over

According to experimental and clinical evidence, the experiences of previous treatments are carried over to different therapeutic approaches and impair the outcome of subsequent treatments. In this behavioral pilot study we used a change in administration route to investigate whether the effect of prior treatment experience on a subsequent treatment depends on the similarity of both treatments. We experimentally induced positive or negative experiences with a topical analgesic treatment in two groups of healthy human subjects. Subsequently, we compared responses to a second, unrelated and systemic analgesic treatment between both the positive and negative group. We found that there was no difference in the analgesic response to the second treatment between the two groups. Our data indicate that a change in administration route might reduce the influence of treatment history and therefore be a way to reduce negative carry-over effects after treatment failure. Future studies will have to validate these findings in a fully balanced design including larger, clinical samples.

Detection of Soluble Fibrin Monomer Complexes in Blood by Means of Protamine Sulphate Test

1968 ◽  
Vol 20 (01/02) ◽  
pp. 044-049 ◽  
Author(s):  
B Lipiński ◽  
K Worowski
Keyword(s):  
Human Subjects ◽  
Coronary Thrombosis ◽  
Mean Value ◽  
Healthy Human ◽  
Protamine Sulphate ◽  
Soluble Fibrin ◽  
Fibrin Monomer ◽  
Dog Plasma ◽  
The Mean ◽  
Precipitable Protein

SummaryIn the present paper described is a simple test for detecting soluble fibrin monomer complexes (SFMC) in blood. The test consists in mixing 1% protamine sulphate with diluted oxalated plasma or serum and reading the optical density at 6190 Å. In experiments with dog plasma, enriched with soluble fibrin complexes, it was shown that OD read in PS test is proportional to the amount of fibrin recovered from the precipitate. It was found that SFMC level in plasma increases in rabbits infused intravenously with thrombin and decreases after injection of plasmin with streptokinase. In both cases PS precipitable protein in serum is elevated indicating enhanced fibrinolysis. In healthy human subjects the mean value of OD readings in plasma and sera were found to be 0.30 and 0.11, while in patients with coronary thrombosis they are 0.64 and 0.05 respectively. The origin of SFMC in circulation under physiological and pathological conditions is discussed.

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