A Direct Comparison of Theta Power and Frequency to Speed and Acceleration.

Decades of hippocampal neurophysiology research have linked the hippocampal theta rhythm to voluntary movement. A consistent observation has been a robust correlation between the amplitude (or power) and frequency of hippocampal theta and running speed. Recently, however, it has been suggested that acceleration, not running speed, is the dominating influence on theta frequency. There is an inherent interdependence among these two variables, as acceleration is the rate of change in velocity. Therefore, we investigated theta frequency and amplitude of the local-field potential recorded from the stratum pyramidale, stratum radiatum, and stratum lacunosum moleculare of the CA1 subregion, considering both speed and acceleration in tandem as animals traversed a circular task or performed continuous alternation. In male and female rats volitionally controlling their own running characteristics, we found that running speed carries nearly all of the variability in theta frequency and power, with a minute contribution from acceleration. These results contradicted a recent publication using a speed-clamping task, where acceleration and movement are compelled through the use of a bottomless car (Kropff et al., 2021a). Therefore, we reanalyzed the speed-clamping data replicating a transient increase in theta frequency during acceleration. Compared with track running rats, the speed-clamped animals exhibited lower velocities and acceleration values but still showed a stronger influence of speed on theta frequency relative to acceleration. As navigation is the integration of many sensory inputs that are not necessarily linearly related, we offer caution in making absolute claims regarding hippocampal physiology from correlates garnered from a single behavioral repertoire.SIGNIFICANCE STATEMENT A long-standing, replicable observation has been the increase of hippocampal theta power and frequency with increasing running speed. Recently, however, an experimental approach that clamps the running speed of an animal has suggested that acceleration is the dominant influence. Therefore, we analyzed data from freely behaving rats as well as data from the speed-clamping experiment. In unrestrained behavior, speed remains the dominant behavioral correlate to theta amplitude and frequency. Positive acceleration in the speed-clamp experiment induced a transient increase in theta frequency and power. However, speed retained the dominant influence over theta frequency, changing with velocity in both acceleration and deceleration conditions.

Theta-gamma cascades and running speed.

Oscillations in the hippocampal local field potential at theta and gamma frequencies are prominent during awake behavior and have demonstrated several behavioral correlates. Both oscillations have been observed to increase in amplitude and frequency as a function of running speed. Previous investigations, however, have examined the relationship between speed and each of these oscillation bands separately. Based on energy cascade models where "…perturbations of slow frequencies cause a cascade of energy dissipation at all frequency scales" (Buzsaki G. Rhythms of the Brain, 2006), we hypothesized that cross-frequency interactions between theta and gamma should increase as a function of speed. We examined these relationships across multiple layers of the CA1 subregion, which correspond to synaptic zones receiving different afferents. Across layers, we found a reliable correlation between the power of theta and the power of gamma, indicative of an amplitude-amplitude relationship. Moreover, there was an increase in the coherence between the power of gamma and the phase of theta, demonstrating increased phase-amplitude coupling with speed. Finally, at higher velocities, phase entrainment between theta and gamma increases. These results have important implications and provide new insights regarding how theta and gamma are integrated for neuronal circuit dynamics, with coupling strength determined by the excitatory drive within the hippocampus. Specifically, rather than arguing that different frequencies can be attributed to different psychological processes, we contend that cognitive processes occur across multiple frequency bands simultaneously with organization occurring as a function of the amount of energy iteratively propagated through the brain. NEW & NOTEWORTHY Often, the theta and gamma oscillations in the hippocampus have been believed to be a consequence of two marginally overlapping phenomena. This perspective, however, runs counter to an alternative hypothesis in which a slow-frequency, high-amplitude oscillation provides energy that cascades into higher frequency, lower amplitude oscillations. We found that as running speed increases, all measures of cross-frequency theta-gamma coupling intensify, providing evidence in favor of the energy cascade hypothesis.

Design for a Nanoscale Single-Photon Spin Splitter for Modes with Orbital Angular Momentum.

We propose using the effective spin-orbit coupling of light in Bragg-modulated cylindrical waveguides for the efficient separation of spin-up and spin-down photons emitted by a single photon emitter. Because of the spin and directional dependence of photonic stop bands in the waveguides, spin-up (-down) photon propagation in the negative (positive) direction along the waveguide axis is blocked while the same photon freely propagates in the opposite direction. Frequency shifts of photonic band structures induced by the spin-orbit coupling are verified by finite-difference time-domain numerical simulations.

[The application of ultrasound for diagnostics of middle ear pathologies].

The objective of the present work was to summarize the results of the application of ultrasound tests for differential diagnostics of various diseases and lesions affecting the middle ear. Almost 7.000 threshold and suprathreshold studies were carried out in the patients presenting with various forms of sensorineural impairment of hearing. The ultrasound investigations were conducted with the use of the EKHOTEST-02 apparatus (Giperion, Moscow). The results of determination of threshold hearing sensitivity to ultrasound and lateralization of its threshold and suprathreshold values suggest their significance for the detection of even such a minimal disturbance in the cochlear function as the phenomenon of accelerated increase in loudness and the associated enhancement of the severity of the damage to the peripheral sensory system.

Reversible optical memory for twisted photons.

We report on an experiment in which orbital angular momentum (OAM) of light is mapped at the single-photon level into and out of a cold atomic ensemble. Based on the dynamic electromagnetically induced transparency protocol, the demonstrated optical memory enables the reversible mapping of Laguerre-Gaussian modes with preserved handedness of the helical phase structure. The demonstrated capability opens the possibility to the storage of qubits encoded as superpositions of OAM states and to multidimensional light matter interfacing.

[Diagnostics of endolymphatic hydrops].

The objective of the present work was to analyse the methods for diagnostics of endolymphatic hydrops associated with Miniere's disease most frequently employed in clinical practice using both the data from the world scientific literature and our own 25-30 year experience based on the observation of more than 500 patients. Camertonal studies of hearing acuity estimated from the results of air conduction measurements and relevant acoumetric curves were considered. The main methods of research are discussed including such as tonal threshold audiometry, ultrasound testing, loud sound lateralization, dehydration test, extratympanic electrocochleography, otoacoustic emission, and functional computed stabilometry. It is concluded that none of the above methods is as reliable as to yield the comprehensive information being sought. All the data obtained by the application of these techniques need to be supplemented by the medical history data, the patients' complaints, clinical signs and symptoms of the disease if the definitive diagnosis of endolymphatic hydrops is to be made.

A novel antivirulent compound fluorothiazinone inhibits Klebsiella pneumoniae biofilm in vitro and suppresses model pneumonia.

The problematic treatment of infections caused by multiple-resistant Klebsiella, especially in ICU, is the leading cause of prolonged hospitalization and high mortality rates. The use of antibiotics for the prevention of infections is considered unreasonable as it may contribute to the selection of resistant bacteria. In this regard, the development of drugs that will be effective in preventing infection during various invasive procedures is extremely necessary. We have shown that the developed innovative antibacterial compound fluorothiazinone (FT) that suppresses the formation of biofilms is effective in the prevention of a model pneumonia caused by a multi-resistant clinical K. pneumoniae isolate. Prophylactic use followed by treatment with FT in mice with acute pneumonia modulates the local innate immune response without suppressing protective properties in the early stages of infection, while contributing to a decrease in the bacterial load in the organs and preventing lethal pathological changes in the lungs at later stages of K. pneumoniae infection. Further development of such antivirulence drugs and their use will reduce morbidity and mortality in nosocomial infections, as well as reduce the number of antibiotics used.

[Vertical integration--an important component of rehabilitation of patients with stroke].

Today it is proved that the reduction of mortality from cardiovascular disease is achieved through the implementation of a coordinated set of measures, the most important of which is to increase public awareness of the risk factors for cardiovascular diseases and their prevention, implementation of effective prevention programs and improve the system of care for stroke.

[The retrospective clinical study of labyrinthine fistula associated with chronic suppurative otitis media and their treatment].

The objective of the present retrospective study was to estimate the efficacy of various surgical techniques employed to treat the patients presenting with chronic suppurative otitis media (CSOM) and concomitant cholesteatoma complicated by labyrinthine fistula. The authors present an overview of the literature concerning diagnostics and results of the surgical treatment of labyrinthine fistula (LF) in the patients with CSOM and concomitant cholesteatoma. The original studies included 157 patients with this condition complicated by labyrinthine fistula. The latter was diagnosed based on the data from medical histories, subjective complaints of the patients, results of otomicroscopy, the presence of fistula symptom verified by the pressure test, results of audiological and vestibulometric studies, and computed tomography (CT) of the temporal bones. Late outcomes of the surgical treatment in the patients presenting with CSOM and concomitant cholesteatoma complicated by LF. All the patients underwent sanitation surgery on the middle ear and revision of the mastoidal portion of the cavity. In 48 of them, cholesteatoma matrix on the fistula in situ was preserved (group 1), in 56 ones the removal of the matrix was followed by plastic correction of labyrinthine fistula using various autogenous tissues (group 2), in 53 patients the cholesteatoma matrix was either removed or preserved with the subsequent sealing of the semicircular canal and selective laser destruction of the labyrinth (LDL) (group 3). 79% of the patients in group 1 had no complaints of dizziness during the postoperative period. There were 78.5% and 96.5% of the patients without such complaints in groups 2 and 3 respectively. The elevation of the hearing threshold following the surgical treatment was documented in 10 (6.4%) patients; it resulted in the deafness in 5 (3%) patients.

Methodological Considerations on the Use of Different Spectral Decomposition Algorithms to Study Hippocampal Rhythms.

Local field potential (LFP) oscillations are primarily shaped by the superposition of postsynaptic currents. Hippocampal LFP oscillations in the 25- to 50-Hz range ("slow γ") are proposed to support memory retrieval independent of other frequencies. However, θ harmonics extend up to 48 Hz, necessitating a study to determine whether these oscillations are fundamentally the same. We compared the spectral analysis methods of wavelet, ensemble empirical-mode decomposition (EEMD), and Fourier transform. EEMD, as previously applied, failed to account for the θ harmonics. Depending on analytical parameters selected, wavelet may convolve over high-order θ harmonics due to the variable time-frequency atoms, creating the appearance of a broad 25- to 50-Hz rhythm. As an illustration of this issue, wavelet and EEMD depicted slow γ in a synthetic dataset that only contained θ and its harmonics. Oscillatory transience cannot explain the difference in approaches as Fourier decomposition identifies ripples triggered to epochs of high-power, 120- to 250-Hz events. When Fourier is applied to high power, 25- to 50-Hz events, only θ harmonics are resolved. This analysis challenges the identification of the slow γ rhythm as a unique fundamental hippocampal oscillation. While there may be instances in which slow γ is present in the rat hippocampus, the analysis presented here shows that unless care is exerted in the application of EEMD and wavelet techniques, the results may be misleading, in this case misrepresenting θ harmonics. Moreover, it is necessary to reconsider the characteristics that define a fundamental hippocampal oscillation as well as theories based on multiple independent γ bands.

[Changes in the tuberculosis epidemiological situation in the areas of the North-Western Federal District of the Russian Federation in 2001-2006].

In the early 21st century, the prevalence rate of tuberculosis infection in the North-West (North-Western Federal District, NWFD) of Russia remains less than the Russian one. There have been no specific changes in the epidemic situation in the past 6 years. It is early to speak about of stabilization as the epidemiological indices are very unsteady. Their nature is suggestive of the preserving tension of the tuberculosis epidemic situation in the NWFD of the Russian Federation.

[Treatment of patients with subjective noise in the ears].

Subjective noise in the ears arises in affection of different systems of a human body (cardiovascular, endocrine, CNS, etc.), but this noise may be also one of the earliest symptoms of different diseases of the ear accompanied, as a rule, with conductive or neurosensory hypoacusis. Phonometry is an indirect psychophysical method of measurement of subjective noise in the ear, and is one of the methods of differential diagnosis of this noise. Current methods of suppression of subjective noise in the ears in chronic neurosensory hypoacusis are sketched. A placebo effect was also achieved.

[Diagnosis of labyrinthine fistula in patients suffering from otitis media purulenta chronica with cholesteatoma: informative value of different methods].

Informative content of different methods of labyrinthine fistulas (LF) diagnosis was assessed in 118 patients suffering from otitis media purulenta chronica (OMPC) with cholesteatoma which ran for 20 years and longer in 82.2% patients, 83.9% had fistula symptom. Unilateral hypoacusis was diagnosed in 68 (57.6%), bilateral--in 50 (42.4%) patients. Severity of vestibular disorders correlated positively with LF size and duration of the disease. Advanced LF was detected in 65 (55.1%) patients, multiple--in 7 (5.9%). Computed tomography of the temporal bone detected LF in all 29 OMPC examinees including "silent" fistulas. Thus, the disease history, clinically manifest fistula symptom and CT of the temporal bone are most informative for diagnosis of LF in OMPC with cholesteatoma.

[A course of early Meniere's disease].

Clinical manifestations are described and examination data are provided for 120 patients with Meniere's disease (MD) running for one year and less (mean 5.2 months). The patients' age varied from 15 to 66 years (mean 39.8 years). Unilateral MD was diagnosed in 95% patients, cochlear MD - in 58.3%, classic one - in the rest patients. Minor or moderate hypoacusis was found in 85% examinees. Mean 18.6 dB bone-air interval at low frequency was detected in 75% patients. Vestibular reflex was reduced insignificantly in 52.5% patients, 45% patients had hypofunction of the third-fourth degree. Early MD was also characterized by ascending or horizontal audiometric curve, positive dehydration test in 85% cases, the acoustic reflex due to accelerated sound intensification in 95% cases, 100% speech intelligibility.

[Laser destruction of labyrinthine receptors as a treatment for benign paroxysmal postural vertigo and otolith symptoms].

Outcomes of surgical laser treatment are presented for 15 patients with resistant to conservative therapy benign paroxysmal postural vertigo (BPPV) and otolith-related disorders. Nine patients with Meniere's disease with BPPV (n=3) and otoliths (in all the patients) were exposed to laser impulses on the bony wall of the horizontal semicircular canal. The impulse was directed in the lumen of the canal in 6 patients with BPPV and otolith symptoms. In Meniere's patients vertigo stopped, hearing was at the preoperative level. Neither threy had BPPV nor otolith problems. The same results were obtained in 6 patients with the other diseases. Vestibular excitability of all surgically treated patients decreased to the fifth degree.

[Indices of the external respiratory function in patients suffering from hepatic cirrhosis with ascitic syndrome].

The changes of external respiration indices in the patients suffering hepatic cirrhosis, complicated by ascitis and portal hypertension, were studied. Application of method of the ascitic liquor extracorporeal ultrafiltration and sorption with its subsequent return into venous system was proposed. The morphological changes of pulmonary parenchyma, which coincided with lowering of the external respiration indices in the patients, were studied.

[Efficacy of conventional methods of treating otitis media purulenta chronica in patients with cholesteatoma and fistula of the labyrinth].

Efficacy of two routine surgical methods was compared in patients with otitis media purulenta chronica having cholesteatoma and fistula. Twenty five patients were operated on the middle ear with preservation of cholesteatoma matrix fragment on fistula of the labyrinth (FL). Forty five patients were operated with plastic reconstruction of the fistula with autotissues. The acoustic and vestibular functions were studied before and after the operation, 3 years later using roentgenography of the temporal bones and high performance computed tomography of the temporal bones. As the results of surgery in both groups of patients were similar, both techniques can be applied in detection of FL at operation. It is shown that in unaffected acoustic and vestibular functions in conditions of active inflammation in the middle ear, it is advisable while operating on the middle ear to preserve matrix of cholesteatoma on FL of any location.

[Tuberculosis in the North-Western Federal Okrug (2000-2004)].

Tuberculosis is an urgent problem in the North-Western Federal Okrug of the Russian Federation. In the past 5 years, the tuberculosis epidemic situation in the okrug has remained to be of strain despite the fact that the spread of tuberculous infection in the North-West is less than in whole Russia. The proper financing of tuberculosis-controlling measures, the solution of a staff-associated problem, and the improvement of the logistic base of a tuberculosis service facility are required to stabilize the tuberculosis situation.

[Albumin-mediated peritoneal dialysis as method of restorational therapy in hepatic insufficiency].

New method of extracorporeal detoxication of organism, which is applied for temporary restoration of hepatic detoxication function in patients with hepatic insufficiency, albumin-mediated peritoneal dialysis, was presented. The main principle of this technology is a transfer through highly permeable dialysis membrane of toxins, which are in affinity with albumin, from the blood to acceptor. The donor's human albumin, circulating in the closed contour, serves as acceptor. The watersoluble lowmolecular substances are excreted according to the concentration gradient. For rapid restoration of acceptoral ability of the donor's albumin solution it was subjected to hemodialysis and carboperfusion. The performance of the procedure guarantees excretion of toxins, combined with albumin, along with excretion of watersoluble toxins.

[Laser destruction of the labyrinth in Meniere's disease: rationale and results]. / Lazerodestruktsiia labirinta pri bolezni Men'era (obosnovanie i rezul'taty).

The authors suggest that Meniere's disease may arise as a psychovegetative syndrome with impairment of labyrinthine homeostasis. It is thought valid to distruct the cupular receptor of the horizontal bony semicircular canal by means of impulse neodymium laser radiation brought to the ampullare bone wall via quartz light guide. Short- and long-term effects of such laser treatment are available. This technique of laser destruction is symptomatic, aimed at relief of severe episodes of vertigo.