Implications on hypnotherapy: Neuroplasticity, epigenetics and pain.

We provide a brief review about the significance of hypnosis with respect to applications and physiological processes in hypnotherapy. Our review concludes that hypnosis is a promising method to manage acute and chronic pain. In addition, we discuss indications pointing toward the view that hypnosis can induce changes in neuroplasticity possibly involving epigenetic mechanisms.

Influence of study design on effects of mask wearing on fMRI BOLD contrast and systemic physiology - A comment on Law et al. (2021).

In a study by Law and colleagues recently published in Neuroimage, the authors reported that wearing a surgical mask during an fMRI scan leads to a statistically significant subject-specific change (30%) in the baseline BOLD level in gray matter, although the response to a sensory-motor task was unaffected. An average increase in end-tidal CO2 of 7.4% was found when wearing a mask, despite little support in the literature for major effects of mask wearing on blood gas levels. We comment on these findings, point out a several relevant limitations of the study design and provide alternative interpretations of these data.

Fluctuations in measured radioactive decay rates inside a modified Faraday cage: Correlations with space weather.

For several years, reports have been published about fluctuations in measured radioactive decay time-series and in some instances linked to astrophysical as well as classical environmental influences. Anomalous behaviors of radioactive decay measurement and measurement of capacitance inside and outside a modified Faraday cage were documented by our group in previous work. In the present report, we present an in-depth analysis of our measurement with regard to possible correlations with space weather, i.e. the geomagnetic activity (GMA) and cosmic-ray activity (CRA). Our analysis revealed that the decay and capacitance time-series are statistically significantly correlated with GMA and CRA when specific conditions are met. The conditions are explained in detail and an outlook is given on how to further investigate this important finding. Our discovery is relevant for all researchers investigating radioactive decay measurements since they point out that the space weather condition during the measurement is relevant for partially explaining the observed variability.

Impact of Skull Thickness on Cerebral NIRS Oximetry in Neonates: An in silico Study.

Monitoring of cerebral tissue oxygen saturation (StO2) by near-infrared spectroscopy (NIRS oximetry) has great potential to reduce the incidence of hypoxic and hyperoxic events and thus prevent long-term disabilities in preterm neonates. Since the light has to penetrate superficial layers (bone, skin and cerebrospinal fluid) before it reaches the brain, the question arises whether these layers influence cerebral StO2 measurement. We assessed this influence on the accuracy of cerebral StO2 values. For that purpose, we simulated light propagation with 'N-layered medium' software. It was found that with a superficial layer thickness of ≤6 mm, typical for term and preterm neonates, StO2 accurately reflects cerebral tissue oxygenation.

Reducing False Alarm Rates in Neonatal Intensive Care: A New Machine Learning Approach.

In neonatal intensive care units (NICUs), 87.5% of alarms by the monitoring system are false alarms, often caused by the movements of the neonates. Such false alarms are not only stressful for the neonates as well as for their parents and caregivers, but may also lead to longer response times in real critical situations. The aim of this project was to reduce the rates of false alarms by employing machine learning algorithms (MLA), which intelligently analyze data stemming from standard physiological monitoring in combination with cerebral oximetry data (in-house built, OxyPrem). MATERIALS & METHODS: Four popular MLAs were selected to categorize the alarms as false or real: (i) decision tree (DT), (ii) 5-nearest neighbors (5-NN), (iii) naïve Bayes (NB) and (iv) support vector machine (SVM). We acquired and processed monitoring data (median duration (SD): 54.6 (± 6.9) min) of 14 preterm infants (gestational age: 26 6/7 (± 2 5/7) weeks). A hybrid method of filter and wrapper feature selection generated the candidate subset for training these four MLAs. RESULTS: A high specificity of >99% was achieved by all four approaches. DT showed the highest sensitivity (87%). The cerebral oximetry data improved the classification accuracy. DISCUSSION & CONCLUSION: Despite a (as yet) low amount of data for training, the four MLAs achieved an excellent specificity and a promising sensitivity. Presently, the current sensitivity is insufficient since, in the NICU, it is crucial that no real alarms are missed. This will most likely be improved by including more subjects and data in the training of the MLAs, which makes pursuing this approach worthwhile.

Near-Infrared Spectroscopy Reveals Brain Hypoxia and Cerebrovascular Dysregulation in Primary Biliary Cholangitis.

BACKGROUND AND AIMS: Primary biliary cholangitis (PBC) is an autoimmune cholestatic liver disease linked to symptoms including fatigue and altered mood/cognition, indicating that chronic liver inflammation associated with PBC can impact brain function. We employed near-infrared spectroscopy (NIRS), a noninvasive neuroimaging technique, to determine whether patients with PBC exhibit reduced cerebral oxygen saturation (StO2 ) and altered patterns of microvascular cerebral blood perfusion and whether these alterations were associated with clinical phenotype. This observational case-control study was conducted at a tertiary hospital clinic (University of Calgary Liver Unit). APPROACH AND RESULTS: Thirteen female patients with noncirrhotic PBC, seven female patients with cirrhotic PBC, and 11 healthy female controls were recruited by physician referral and word of mouth, respectively. NIRS was used to measure cerebral hemoglobin and oxygen saturation. A wavelet phase coherence method was used to estimate the coherent frequency coupling of temporal changes in cerebral hemodynamics. The PBC group demonstrated significantly reduced cerebral StO2 (P = 0.01, d = 0.84), indicating cerebral hypoxia, significantly increased cerebral deoxygenated hemoglobin concentration (P < 0.01, d = 0.86), and significantly reduced hemodynamic coherence in the low-frequency band (0.08-0.15 Hz) for oxygenated hemoglobin concentration (P = 0.02, d = 0.99) and total hemoglobin (tHb) concentration (P = 0.02, d = 0.50), indicating alterations in cerebrovascular activity. Complete biochemical response to ursodeoxycholic acid (UDCA) therapy in early patients with PBC was associated with increased cerebral tHb concentration and decreased hemodynamic coherence. CONCLUSIONS: Using NIRS, patients with PBC were found to have hypoxia, increased cerebral hemoglobin concentration, and altered cerebrovascular activity, which were reversed in part in UDCA responders. In addition, symptoms and quality-of-life measures did not correlate with brain hypoxia or cerebrovascular dysregulation in patients with PBC.

The Resting-State Pulse-Respiration Quotient of Humans: Lognormally Distributed and Centered Around a Value of Four.

The pulse-respiration quotient (heart rate divided by the respiration rate, PRQ = HR/RR) is a parameter capturing the complex state of cardiorespiratory interactions. We analysed 482 single PRQ values obtained from measurement on 134 healthy adult subjects (49 men, 85 women, age: 24.7 ± 3.4, range: 20-46 years) during rest. We found that the distribution of PRQ values (i) has a global maximum at around a value of 4 (median: 4.19) and (ii) follows a lognormal distribution function. A multimodality of the distribution, associated with several PRQ attractor states was not detected by our group-level based analysis. In summary, our analysis shows that in healthy humans the resting-state PRQ is around 4 and lognormally distributed. This finding supports claims about the special role of the 4 to 1 cardiorespiratory coupling in particular and the PRQ in general for physiological and medical views and applications. To the best of our knowledge, our study is the largest conducted so far in healthy adult humans about reference values of the PRQ during a resting-state at day.

Comparison of tissue oximeters on a liquid phantom with adjustable optical properties: an extension.

Cerebral near-infrared spectroscopy (NIRS) oximetry may help clinicians to improve patient treatment. However, the application of NIRS oximeters is increasingly causing confusion to the users due to the inconsistency of tissue oxygen haemoglobin saturation (StO2) readings provided by different oximeters. To establish a comparability of oximeters, in our study we performed simultaneous measurements on the liquid phantom mimicking properties of neonatal heads and compared the tested device to a reference NIRS oximeter (OxiplexTS). We evaluated the NIRS oximeters FORE-SIGHT, NIRO and SenSmart, and reproduced previous results with the INVOS and OxyPrem v1.3 oximeters. In general, linear relationships of the StO2 values with respect to the reference were obtained. Device specific hypoxic and hyperoxic thresholds (as used in the SafeBoosC study, www.safeboosc.eu) and a table allowing for conversion of StO2 values are provided.

Continuous coloured light altered human brain haemodynamics and oxygenation assessed by systemic physiology augmented functional near-infrared spectroscopy.

Exposure to artificial coloured light is unavoidable in our modern life, but we are only just beginning to understand the impact of coloured light on human physiology. The aim of the present study was to determine effects of coloured light exposure on human systemic and brain physiology using systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS). We measured changes in haemoglobin concentrations and tissue oxygen saturation in the left and right prefrontal cortices (L-PFC, R-PFC) by fNIRS, and also recorded skin conductance (SC), partial pressure of end-tidal CO2 (PETCO2), and heart-rate variability variables. 17 healthy adults (median age: 29 years, range: 25-65 years, 6 women) were exposed to blue, red, green, or yellow light for 10 minutes. Pre-light and post-light conditions were in darkness. In the L-PFC the yellow evoked a brain activation. SC and PETCO2 did not change during any of the coloured light exposures, but SC increased and PETCO2 decreased for all colours (except green) in the post-light period. Changes in L-PFC haemoglobin concentration were also observed during the post-light period but have to be interpreted with care, because heart rate and SC increased while PETCO2 decreased. The detected effects are potentially of high relevance for choosing room lighting and may possibly be applied therapeutically.

Physiological Effects of Continuous Colored Light Exposure on Mayer Wave Activity in Cerebral Hemodynamics: A Functional Near-Infrared Spectroscopy (fNIRS) Study.

We are increasingly exposed to colored light, but its impact on human physiology is not yet extensively investigated. In the present study we aimed to determine the effects of colored light on human cerebral Mayer wave activity (MWA). We measured oxy- ([O2Hb]), deoxy- ([HHb]), total hemoglobin ([tHb]) concentrations and tissue oxygen saturation (StO2) by functional near-infrared spectroscopy (fNIRS) in the left and right pre-frontal cortex (L-PFC, R-PFC) of 17 subjects (median age: 29 years, 6 women). In a randomized crossover design subjects were exposed to blue, red, green, and yellow LED light for 10 min. Pre-light (8 min, baseline) and post-light (15 min, recovery) conditions were darkness. MWA was calculated from band-pass filtered fNIRS signals (~0.08-0.12 Hz). The medians from the last 3 min of each period (baseline, light exposure, recovery) were statistically analyzed. MWA was increased during red and green light vs. baseline and after blue light exposure in recovery in the L-PFC. MWA differed depending on the chosen frequency range, filter design, and type of signals to analyze (raw intensity, hemoglobin signal from multi-distance method or modified Beer-Lambert law, or within hemoglobin signals).

Prefrontal hemodynamic after-effects caused by rebreathing may predict affective states - A multimodal functional near-infrared spectroscopy study.

Brain activity has been shown to be influenced by respiratory behavior. Here, we evaluated whether respiration-induced hypo- or hypercapnia may support differentiation between physiological versus pathological respiratory behavior. In particular, we investigated whether systemic physiological measures could predict the brain's time-frequency hemodynamics after three respiratory challenges (i.e., breath-holding, rebreathing, and hyperventilation) compared to resting-state. Prefrontal hemodynamics were assessed in healthy subjects (N = 27) using functional near-infrared spectroscopy (fNIRS). Systemic physiological measures were assessed in form of heart rate, partial end-tidal carbon dioxide, respiration rate, and saturation of peripheral oxygen. Time-frequency dynamics were quantified using the wavelet transform coherence (i.e., defined here as cortical-systemic coherence). We found that the three respiratory challenges modulated cortical-systemic coherence differently: (1) After rebreathing, cortical-systemic coherence could be predicted from the amplitude of the heart rate (strong negative correlation). (2) After breath-holding, the same observation was made (moderate negative correlation). (3) After hyperventilation, no significant effect was observed. (4) These effects were found only in the frequency range of very low-frequency oscillations. The presented findings highlight a distinct role of rebreathing in predicting cortical-systemic coupling based on heart rate changes, which may represents a measure of affective states in the brain. The applied multimodal assessment of hemodynamic and systemic physiological measures during respiratory challenges may therefore have potential applications in the differentiation between physiological and pathological respiratory behavior.

Simulation of Preterm Neonatal Brain Metabolism During Functional Neuronal Activation Using a Computational Model.

We present a computational model of metabolism in the preterm neonatal brain. The model has the capacity to mimic haemodynamic and metabolic changes during functional activation and simulate functional near-infrared spectroscopy (fNIRS) data. As an initial test of the model's efficacy, we simulate data obtained from published studies investigating functional activity in preterm neonates. In addition we simulated recently collected data from preterm neonates during visual activation. The model is well able to predict the haemodynamic and metabolic changes from these observations. In particular, we found that changes in cerebral blood flow and blood pressure may account for the observed variability of the magnitude and sign of stimulus-evoked haemodynamic changes reported in preterm infants.

Time-frequency dynamics of the sum of intra- and extracerebral hemodynamic functional connectivity during resting-state and respiratory challenges assessed by multimodal functional near-infrared spectroscopy.

Monitoring respiratory processes is important for evaluating neuroimaging data, given their influence on time-frequency dynamics of intra- and extracerebral hemodynamics. Here we investigated the time-frequency dynamics of the sum of intra- and extracerebral hemodynamic functional connectivity states during hypo- and hypercapnia by using three different respiratory challenge tasks (i.e., hyperventilation, breath-holding, and rebreathing) compared to resting-state. The sum of intra- and extracerebral hemodynamic responses were assessed using functional near-infrared spectroscopy (fNIRS) within two regions of interest (i.e., the dorsolateral and the medial prefrontal cortex). Time-frequency fNIRS analysis was performed based on wavelet transform coherence to quantify functional connectivity in terms of positive and negative phase-coupling within each region of interest. Physiological measures were assessed in the form of partial end-tidal carbon dioxide, heart rate, arterial tissue oxygen saturation, and respiration rate. We found that the three respiration challenges modulated time-frequency dynamics differently with respect to resting-state: 1) Hyperventilation and breath-holding exhibited inverse patterns of positive and negative phase-coupling. 2) In contrast, rebreathing had no significant effect. 3) Low-frequency oscillations contributed to a greater extent to time-frequency dynamics compared to high-frequency oscillations. The results highlight that there exist distinct differences in time-frequency dynamics of the sum of intra- and extracerebral functional connectivity not only between hypo- (hyperventilation) and hypercapnia but also between different states of hypercapnia (breath-holding versus rebreathing). This suggests that a multimodal assessment of intra-/extracerebral and systemic physiological changes during respiratory challenges compared to resting-state may have potential use in the differentiation between physiological and pathological respiratory behavior accompanied by the psycho-physiological state of a human.

A study of quantum mechanical probabilities in the classical Hodgkin-Huxley model.

The Hodgkin-Huxley (HH) model is a powerful model to explain different aspects of spike generation in excitable cells. However, the HH model was proposed in 1952 when the real structure of the ion channel was unknown. It is now common knowledge that in many ion-channel proteins the flow of ions through the pore is governed by a gate, comprising a so-called "selectivity filter" inside the ion channel, which can be controlled by electrical interactions. The selectivity filter (SF) is believed to be responsible for the selection and fast conduction of particular ions across the membrane of an excitable cell. Other (generally larger) parts of the molecule such as the pore-domain gate control the access of ions to the channel protein. In fact, two types of gates are considered here for ion channels: the "external gate", which is the voltage sensitive gate, and the "internal gate" which is the selectivity filter gate (SFG). Some quantum effects are expected in the SFG due to its small dimensions, which may play an important role in the operation of an ion channel. Here, we examine parameters in a generalized model of HH to see whether any parameter affects the spike generation. Our results indicate that the previously suggested semi-quantum-classical equation proposed by Bernroider and Summhammer (BS) agrees strongly with the HH equation under different conditions and may even provide a better explanation in some cases. We conclude that the BS model can refine the classical HH model substantially.

End-tidal CO2: an important parameter for a correct interpretation in functional brain studies using speech tasks.

The aim was to investigate the effect of different speech tasks, i.e. recitation of prose (PR), alliteration (AR) and hexameter (HR) verses and a control task (mental arithmetic (MA) with voicing of the result on end-tidal CO2 (PETCO2), cerebral hemodynamics and oxygenation. CO2 levels in the blood are known to strongly affect cerebral blood flow. Speech changes breathing pattern and may affect CO2 levels. Measurements were performed on 24 healthy adult volunteers during the performance of the 4 tasks. Tissue oxygen saturation (StO2) and absolute concentrations of oxyhemoglobin ([O2Hb]), deoxyhemoglobin ([HHb]) and total hemoglobin ([tHb]) were measured by functional near-infrared spectroscopy (fNIRS) and PETCO2 by a gas analyzer. Statistical analysis was applied to the difference between baseline before the task, 2 recitation and 5 baseline periods after the task. The 2 brain hemispheres and 4 tasks were tested separately. A significant decrease in PETCO2 was found during all 4 tasks with the smallest decrease during the MA task. During the recitation tasks (PR, AR and HR) a statistically significant (p<0.05) decrease occurred for StO2 during PR and AR in the right prefrontal cortex (PFC) and during AR and HR in the left PFC. [O2Hb] decreased significantly during PR, AR and HR in both hemispheres. [HHb] increased significantly during the AR task in the right PFC. [tHb] decreased significantly during HR in the right PFC and during PR, AR and HR in the left PFC. During the MA task, StO2 increased and [HHb] decreased significantly during the MA task. We conclude that changes in breathing (hyperventilation) during the tasks led to lower CO2 pressure in the blood (hypocapnia), predominantly responsible for the measured changes in cerebral hemodynamics and oxygenation. In conclusion, our findings demonstrate that PETCO2 should be monitored during functional brain studies investigating speech using neuroimaging modalities, such as fNIRS, fMRI to ensure a correct interpretation of changes in hemodynamics and oxygenation.

Changes in hemodynamics and tissue oxygenation saturation in the brain and skeletal muscle induced by speech therapy - a near-infrared spectroscopy study.

Arts speech therapy (AST) is a therapeutic method within complementary medicine and has been practiced for decades for various medical conditions. It comprises listening and the recitation of different forms of speech exercises under the guidance of a licensed speech therapist. The aim of our study was to noninvasively investigate whether different types of recitation influence hemodynamics and oxygenation in the brain and skeletal leg muscle using near-infrared spectroscopy (NIRS). Seventeen healthy volunteers (eight men and nine women, mean age ± standard deviation 35.6 ± 12.7 years) were enrolled in the study. Each subject was measured three times on different days with the different types of recitation: hexameter, alliteration, and prose verse. Before, during, and after recitation, relative concentration changes of oxyhemoglobin (Δ[O2Hb]), deoxyhemoglobin (Δ[HHb]), total hemoglobin (Δ[tHb]), and tissue oxygenation saturation (StO2) were measured in the brain and skeletal leg muscle using a NIRS device. The study was performed with a randomized crossover design. Significant concentration changes were found during recitation of all verses, with mainly a decrease in Δ[O2Hb] and ΔStO2 in the brain, and an increase in Δ[O2Hb] and Δ[tHb] in the leg muscle during recitation. After the recitations, significant changes were mainly increases of Δ[HHb] and Δ[tHb] in the calf muscle. The Mayer wave spectral power (MWP) was also significantly affected, i.e., mainly the MWP of the Δ[O2Hb] and Δ[tHb] increased in the brain during recitation of hexameter and prose verse. The changes in MWP were also significantly different between hexameter and alliteration, and hexameter and prose. Possible physiological explanations for these changes are discussed. A probable reason is a different effect of recitations on the sympathetic nervous system. In conclusion, these changes show that AST has relevant effects on the hemodynamics and oxygenation of the brain and muscle.

How to detect and reduce movement artifacts in near-infrared imaging using moving standard deviation and spline interpolation.

Near-infrared imaging (NIRI) is a neuroimaging technique which enables us to non-invasively measure hemodynamic changes in the human brain. Since the technique is very sensitive, the movement of a subject can cause movement artifacts (MAs), which affect the signal quality and results to a high degree. No general method is yet available to reduce these MAs effectively. The aim was to develop a new MA reduction method. A method based on moving standard deviation and spline interpolation was developed. It enables the semi-automatic detection and reduction of MAs in the data. It was validated using simulated and real NIRI signals. The results show that a significant reduction of MAs and an increase in signal quality are achieved. The effectiveness and usability of the method is demonstrated by the improved detection of evoked hemodynamic responses. The present method can not only be used in the postprocessing of NIRI signals but also for other kinds of data containing artifacts, for example ECG or EEG signals.