0071 A Medullary Circuit Controlling REM Sleep

Abstract Introduction Rapid eye movement (REM) sleep is a distinct brain state known for its association with vivid dreaming in humans, though it is also crucial for other mental processes such as memory consolidation and emotion regulation. REM sleep is punctuated by phasic neurophysiological events known as pontine (P)-waves, which are thought to contribute to the cognitive functions of REM sleep. However, little is known about the neural circuits regulating these P-waves, or those responsible for initiating REM sleep itself. Here, we show that a yet unstudied population of medullary neurons expressing corticotropin-releasing-hormone (CRH) are important for controlling both the induction of REM sleep and its phasic events. Methods To measure the endogenous activity of CRH+ neurons in the dorsomedial medulla (dmM), we injected the calcium indicator GCaMP6 in the dmM of CRH-Cre mice. To optogenetically manipulate dmM CRH+ neuron activity, we delivered either an excitatory (ChR2) or inhibitory (iC++) opsin to the dmM of CRH-Cre mice. To record P-waves, we implanted microelectrodes to record local field potentials in the subcoeruleus region of the pons. Results Fiber photometry recordings showed that dmM CRH+ neurons are selectively active during REM sleep, and optogenetic stimulation and inhibition of this population is sufficient to promote and reduce REM sleep, respectively. Additionally, dmM CRH+ neuron activity is correlated with P-waves in the pons, and optogenetic activation of dmM CRH+ cells reliably triggers P-waves during REM sleep. Finally, histological examination of fluorescently labeled dmM CRH+ axons revealed strong projections to several pontine areas involved in P-wave generation as well as modulation of the theta rhythm during REM sleep. Conclusion Our results suggest that dmM CRH+ neurons are involved in controlling REM sleep initiation as well as phasic events within REM sleep. These neurons thus constitute an important component of the brainstem circuitry regulating REM sleep. Support National Institutes of Health (R01 HL149133)

Download Full-text

0074 Inhibitory Neurons in the Dorsomedial Medulla Promote REM Sleep

SLEEP ◽

10.1093/sleep/zsaa056.072 ◽

2020 ◽

Vol 43 (Supplement_1) ◽

pp. A30-A30

Author(s):

J Stucynski ◽

A Schott ◽

J Baik ◽

J Hong ◽

F Weber ◽

...

Keyword(s):

Rem Sleep ◽

Nrem Sleep ◽

Inhibitory Neurons ◽

Brain State ◽

Sleep Regulation ◽

Optogenetic Stimulation ◽

Electrophysiological Recordings ◽

Stimulation Of

Abstract Introduction The neural circuits controlling rapid eye movement (REM) sleep, and in particular the role of the medulla in regulating this brain state, remains an active area of study. Previous electrophysiological recordings in the dorsomedial medulla (DM) and electrical stimulation experiments suggested an important role of this area in the control of REM sleep. However the identity of the involved neurons and their precise role in REM sleep regulation are still unclear. Methods The properties of DM GAD2 neurons in mice were investigated through stereotaxic injection of CRE-dependent viruses in conjunction with implantation of electrodes for electroencephalogram (EEG) and electromyogram (EMG) recordings and optic fibers. Experiments included in vivo calcium imaging (fiber photometry) across sleep and wake states, optogenetic stimulation of cell bodies, chemogenetic excitation and suppression (DREADDs), and connectivity mapping using viral tracing and optogenetics. Results Imaging the calcium activity of DM GAD2 neurons in vivo indicates that these neurons are most active during REM sleep. Optogenetic stimulation of DM GAD2 neurons reliably triggered transitions into REM sleep from NREM sleep. Consistent with this, chemogenetic activation of DM GAD2 neurons increased the amount of REM sleep while inhibition suppressed its occurrence and enhanced NREM sleep. Anatomical tracing revealed that DM GAD2 neurons project to several areas involved in sleep / wake regulation including the wake-promoting locus coeruleus (LC) and the REM sleep-suppressing ventrolateral periaquaductal gray (vlPAG). Optogenetic activation of axonal projections from DM to LC, and DM to vlPAG was sufficient to induce REM sleep. Conclusion These experiments demonstrate that DM inhibitory neurons expressing GAD2 powerfully promote initiation of REM sleep in mice. These findings further characterize the dorsomedial medulla as a critical structure involved in REM sleep regulation and inform future investigations of the REM sleep circuitry. Support R01 HL149133

Download Full-text

Enhancement of Synchronization Between Hippocampal and Amygdala Theta Waves Associated With Pontine Wave Density

Journal of Neurophysiology ◽

10.1152/jn.00551.2009 ◽

2010 ◽

Vol 103 (5) ◽

pp. 2318-2325 ◽

Cited By ~ 16

Author(s):

Akihiro Karashima ◽

Norihiro Katayama ◽

Mitsuyuki Nakao

Keyword(s):

Rem Sleep ◽

Cross Correlation ◽

P Wave ◽

Retrieval Process ◽

P Waves ◽

Neuronal Communication ◽

Theta Wave ◽

Theta Waves ◽

Theta Frequency ◽

Hippocampal Theta

Theta waves in the amygdala are known to be synchronized with theta waves in the hippocampus. Synchronization between amygdala and hippocampal theta waves is considered important for neuronal communication between these regions during the memory-retrieval process. These theta waves are also observed during rapid eye movement (REM) sleep. However, few studies have examined the mechanisms and functions of theta waves during REM sleep. This study examined correlations between the dynamics of hippocampal and amygdala theta waves and pontine (P) waves in the subcoeruleus region, which activates many brain areas including the hippocampus and amygdala, during REM sleep in rats. We confirmed that the frequency of hippocampal theta waves increased in association with P wave density, as shown in our previous study. The frequency of amygdala theta waves also increased with in associated with P wave density. In addition, we confirmed synchronization between hippocampal and amygdala theta waves during REM sleep in terms of the cross-correlation function and found that this synchronization was enhanced in association with increased P wave density. We further studied theta wave synchronization associated with P wave density by lesioning the pontine subcoeruleus region. This lesion not only decreased hippocampal and amygdala theta frequency, but also degraded theta wave synchronization. These results indicate that P waves enhance synchronization between regional theta waves. Because hippocampal and amygdala theta waves and P waves are known to be involved in learning and memory processes, these results may help clarify these functions during REM sleep.

Download Full-text

Simulation of thermoelastic waves based on the Lord-Shulman theory

Geophysics ◽

10.1190/geo2020-0515.1 ◽

2021 ◽

Vol 86 (3) ◽

pp. T155-T164

Author(s):

Wanting Hou ◽

Li-Yun Fu ◽

José M. Carcione ◽

Zhiwei Wang ◽

Jia Wei

Keyword(s):

Thermal Conductivity ◽

Expansion Coefficient ◽

Velocity Dispersion ◽

Wave Attenuation ◽

Splitting Method ◽

Grazing Incidence ◽

P Wave ◽

Staggered Grid ◽

Thermal Mode ◽

P Waves

Thermoelasticity is important in seismic propagation due to the effects related to wave attenuation and velocity dispersion. We have applied a novel finite-difference (FD) solver of the Lord-Shulman thermoelasticity equations to compute synthetic seismograms that include the effects of the thermal properties (expansion coefficient, thermal conductivity, and specific heat) compared with the classic forward-modeling codes. We use a time splitting method because the presence of a slow quasistatic mode (the thermal mode) makes the differential equations stiff and unstable for explicit time-stepping methods. The spatial derivatives are computed with a rotated staggered-grid FD method, and an unsplit convolutional perfectly matched layer is used to absorb the waves at the boundaries, with an optimal performance at the grazing incidence. The stability condition of the modeling algorithm is examined. The numerical experiments illustrate the effects of the thermoelasticity properties on the attenuation of the fast P-wave (or E-wave) and the slow thermal P-wave (or T-wave). These propagation modes have characteristics similar to the fast and slow P-waves of poroelasticity, respectively. The thermal expansion coefficient has a significant effect on the velocity dispersion and attenuation of the elastic waves, and the thermal conductivity affects the relaxation time of the thermal diffusion process, with the T mode becoming wave-like at high thermal conductivities and high frequencies.

Download Full-text

Estimates of velocity structure and source depth using multiple P waves from aftershocks of the 1987 Elmore Ranch and Superstition Hills, California, earthquakes

Bulletin of the Seismological Society of America ◽

10.1785/bssa0810020508 ◽

1991 ◽

Vol 81 (2) ◽

pp. 508-523

Author(s):

Jim Mori

Keyword(s):

Velocity Structure ◽

Velocity Model ◽

P Wave ◽

Sediment Layer ◽

Source Depth ◽

Imperial Valley ◽

P Waves ◽

Main Shocks ◽

Aftershock Sequences ◽

Event Record

Abstract Event record sections, which are constructed by plotting seismograms from many closely spaced earthquakes recorded on a few stations, show multiple free-surface reflections (PP, PPP, PPPP) of the P wave in the Imperial Valley, California. The relative timing of these arrivals is used to estimate the strength of the P-wave velocity gradient within the upper 5 km of the sediment layer. Consistent with previous studies, a velocity model with a value of 1.8 km/sec at the surface increasing linearly to 5.8 km/sec at a depth of 5.5 km fits the data well. The relative amplitudes of the P and PP arrivals are used to estimate the source depth for the aftershock distributions of the Elmore Ranch and Superstition Hills main shocks. Although the depth determination has large uncertainties, both the Elmore Ranch and Superstition Hills aftershock sequences appear to have similar depth distribution in the range of 4 to 10 km.

Download Full-text

Reflection moveout approximations for P-waves in a moderately anisotropic homogeneous tilted transverse isotropy layer

Geophysics ◽

10.1190/geo2016-0381.1 ◽

2017 ◽

Vol 82 (5) ◽

pp. C175-C185 ◽

Cited By ~ 6

Author(s):

Ivan Pšenčík ◽

Véronique Farra

Keyword(s):

Transverse Isotropy ◽

Transversely Isotropic ◽

P Wave ◽

Weak Anisotropy ◽

P Waves ◽

3D Space ◽

Axis Of Symmetry ◽

Relative Errors ◽

Symmetry Tests ◽

Ti Media

We have developed approximate nonhyperbolic P-wave moveout formulas applicable to weakly or moderately anisotropic media of arbitrary anisotropy symmetry and orientation. Instead of the commonly used Taylor expansion of the square of the reflection traveltime in terms of the square of the offset, we expand the square of the reflection traveltime in terms of weak-anisotropy (WA) parameters. No acoustic approximation is used. We specify the formulas designed for anisotropy of arbitrary symmetry for the transversely isotropic (TI) media with the axis of symmetry oriented arbitrarily in the 3D space. Resulting formulas depend on three P-wave WA parameters specifying the TI symmetry and two angles specifying the orientation of the axis of symmetry. Tests of the accuracy of the more accurate of the approximate formulas indicate that maximum relative errors do not exceed 0.3% or 2.5% for weak or moderate P-wave anisotropy, respectively.

Download Full-text

Physiological ECG Value for Polish Half-Bred Anglo-Arab Horses

Bulletin of the Veterinary Institute in Pulawy ◽

10.2478/v10213-012-0111-4 ◽

2012 ◽

Vol 56 (4) ◽

pp. 631-635 ◽

Cited By ~ 1

Keyword(s):

Heart Rate ◽

P Wave ◽

P Waves ◽

T Wave ◽

Duration Time ◽

Qt Intervals ◽

Electrocardiographic Examination ◽

Electrocardiographic Findings ◽

Almost All ◽

T Waves

Abstract The electrocardiographic examination was performed in 33 training horses (2-16 years of age, 11 males and 22 females). Einthoven and precordial leads (I, II, III, aVR, aVL, aVF, CV1, CV2, CV4) were used. The ECG was performed in resting horses and immediately after exercise (10 min walk, 15 min trot, 10 min canter) using a portable Schiller AT-1 3-channel electrocardiograph, with a paper speed of 25 mm sec-1 and a sensitivity of 10 mm.mV-1. The heart rate, wave amplitudes, and duration time were estimated manually. All horses presented a significant increase in heart rate after exercise (rest 43.83 ±10.33 vs. exercise 73.2 ±14.8). QT intervals were significantly shortened in most of the leads. In resting horses, all P waves in the lead I were positive and almost all II, III and CV4 leads were positive. Simple negative P wave dominated in aVR and only simple negative T wave was found in the leads I. The biphasic shape was observed. After exercise, the amplitude of P and T waves rose, however, clear changes were not observed in wave polarisation and form. In the absence of specific racial characteristics of the electrocardiogram in the Polish Anglo- Arabians, electrocardiographic findings can be interpreted according to ECG standards adopted for horses.

Download Full-text

Beat-to-Beat P-Wave Analysis Outperforms Conventional P-Wave Indices in Identifying Patients with a History of Paroxysmal Atrial Fibrillation during Sinus Rhythm

Diagnostics ◽

10.3390/diagnostics11091694 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1694

Author(s):

Dimitrios Tachmatzidis ◽

Dimitrios Filos ◽

Ioanna Chouvarda ◽

Anastasios Tsarouchas ◽

Dimitrios Mouselimis ◽

...

Keyword(s):

Atrial Fibrillation ◽

Sinus Rhythm ◽

Paroxysmal Atrial Fibrillation ◽

Univariate Analysis ◽

Multivariate Logistic Regression Analysis ◽

P Wave ◽

P Value ◽

Wave Analysis ◽

P Waves ◽

History Of

Early identification of patients at risk for paroxysmal atrial fibrillation (PAF) is essential to attain optimal treatment and a favorable prognosis. We compared the performance of a beat-to-beat (B2B) P-wave analysis with that of standard P-wave indices (SPWIs) in identifying patients prone to PAF. To this end, 12-lead ECG and 10 min vectorcardiogram (VCG) recordings were obtained from 33 consecutive, antiarrhythmic therapy naïve patients, with a short history of low burden PAF, and from 56 age- and sex-matched individuals with no AF history. For both groups, SPWIs were calculated, while the VCG recordings were analyzed on a B2B basis, and the P-waves were classified to a primary or secondary morphology. Wavelet transform was used to further analyze P-wave signals of main morphology. Univariate analysis revealed that none of the SPWIs performed acceptably in PAF detection, while five B2B features reached an AUC above 0.7. Moreover, multivariate logistic regression analysis was used to develop two classifiers—one based on B2B analysis derived features and one using only SPWIs. The B2B classifier was found to be superior to SPWIs classifier; B2B AUC: 0.849 (0.754–0.917) vs. SPWIs AUC: 0.721 (0.613–0.813), p value: 0.041. Therefore, in the studied population, the proposed B2B P-wave analysis outperforms SPWIs in detecting patients with PAF while in sinus rhythm. This can be used in further clinical trials regarding the prognosis of such patients.

Download Full-text

P- waves reflected from the "20" discontinuity" beneath the Mediterranean region

Annals of Geophysics ◽

10.4401/ag-4892 ◽

2010 ◽

Vol 28 (1) ◽

Author(s):

A BOTTARI ◽

B. FEDERICO

Keyword(s):

Mediterranean Area ◽

P Wave ◽

Travel Times ◽

P Waves ◽

First Order ◽

P Wave Velocity ◽

Different Depths ◽

The Mediterranean ◽

Regional Character ◽

Order Discontinuity

The observed travel-times of the P-waves for twenty shallow, intermediate, and deep earthquakes, with epicenters in the Mediterranean area, are used in order to analyze some characteristics of the upper mantle. A first- order discontinuity, identifiable as the "20° discontinuity", is found at a depth of 505 ± 16 km in the area underneath the Mediterranean basin. The velocity contrast is equal to 12% (above T'= 8.9 km/sec; below V= 9.97 km/sec). Assuming that this discontinuity gives rise to reflected P-waves (PdP), the travel times of these waves are calculated for various hypocentral depths. The observation of impulses identified as PdP on the seismograms of Messina supports this hypothesis. This result and its implications are discussed in the contest of the conclusions of various authors who locate a P-wave velocity-discontinuity at different depths between 400 and 580 km. Finally, particular emphasis is given to the regional character of the analyzed structures in question.

Download Full-text

Numerical simulation of azimuthal acoustic logging in a borehole penetrating a rock formation boundary

Geophysics ◽

10.1190/geo2015-0265.1 ◽

2016 ◽

Vol 81 (3) ◽

pp. D283-D291 ◽

Cited By ~ 4

Author(s):

Peng Liu ◽

Wenxiao Qiao ◽

Xiaohua Che ◽

Xiaodong Ju ◽

Junqiang Lu ◽

...

Keyword(s):

Domain Model ◽

P Wave ◽

S Wave ◽

Angle Variation ◽

P Waves ◽

Acoustic Logging ◽

S Waves ◽

Rock Formation ◽

Logging Tool ◽

Difference Time

We have developed a new 3D acoustic logging tool (3DAC). To examine the azimuthal resolution of 3DAC, we have evaluated a 3D finite-difference time-domain model to simulate a case in which the borehole penetrated a rock formation boundary when the tool worked at the azimuthal-transmitting-azimuthal-receiving mode. The results indicated that there were two types of P-waves with different slowness in waveforms: the P-wave of the harder rock (P1) and the P-wave of the softer rock (P2). The P1-wave can be observed in each azimuthal receiver, but the P2-wave appears only in the azimuthal receivers toward the softer rock. When these two types of rock are both fast formations, two types of S-waves also exist, and they have better azimuthal sensitivity compared with P-waves. The S-wave of the harder rock (S1) appears only in receivers toward the harder rock, and the S-wave of the softer rock (S2) appears only in receivers toward the softer rock. A model was simulated in which the boundary between shale and sand penetrated the borehole but not the borehole axis. The P-wave of shale and the S-wave of sand are azimuthally sensitive to the azimuth angle variation of two formations. In addition, waveforms obtained from 3DAC working at the monopole-transmitting-azimuthal-receiving mode indicate that the corresponding P-waves and S-waves are azimuthally sensitive, too. Finally, we have developed a field example of 3DAC to support our simulation results: The azimuthal variation of the P-wave slowness was observed and can thus be used to reflect the azimuthal heterogeneity of formations.

Download Full-text

Analysis of six cancer patients with persistent left superior vena cava identified during central venous access device placement via an intracavitary electrocardiogram

The Journal of Vascular Access ◽

10.1177/11297298211045576 ◽

2021 ◽

pp. 112972982110455

Author(s):

Xinpeng Wang ◽

Yong Yang ◽

Jing Dong ◽

Xiaozheng Wang ◽

Yuanyuan Zheng ◽

...

Keyword(s):

Body Surface ◽

Superior Vena ◽

Central Venous Access ◽

Vena Cava ◽

Venous Access ◽

The Body ◽

P Wave ◽

P Waves ◽

Venous Access Device ◽

Surface Electrocardiogram

Persistent left superior vena cava (PLSVC) is a rare congenital anomaly. PLSVC can be associated with clinically significant atrial septal defect (ASD) or ventricular septal defect (VSD). It is usually asymptomatic and accidentally detected during invasive procedures or imaging examinations. However, whether central venous access device (CVAD) can be placed and used in patients with PLSVC is controversial. A total of six patients were diagnosed with PLSVC and confirmed by chest CT among 3391 cancer patients who underwent CVAD placement via intracavitary electrocardiogram (IC-EKG) at the Venous Access Center (VAC) from May 2019 to December 2020. The CVADs (peripherally inserted central catheter in four patients and Ports in two patients) of these six patients were left in PLSVC. We analyzed changes in the P-wave in the IC-EKG during CVAD placement and the characteristics of the body surface electrocardiogram in these patients and discussed the catheter tip position in PLSVC. All six patients showed negative P-waves in lead II via IC-EKG from the beginning of catheterization: four patients showed negative P-waves and two showed biphasic P-waves in the body surface electrocardiogram (lead III) before catheterization. CVAD function was normal and no obvious complications were observed during the treatment of these patients. The total retention time of CVADs was 1537 days. For patients with a negative P-wave in lead II via IC-EKG during catheterization, especially in those with a negative or biphasic P-wave in lead III of the body surface electrocardiogram, PLSVC should be considered. CVAD insertion in patients with type I PLSVC is safe under certain conditions, with the proper tip position in the middle to lower part of PLSVC.

Download Full-text