Vztahy mezi oscilacemi a jejich využití u adaptivní hluboké mozkové stimulace

Hluboká mozková stimulace (DBS) patří vedle dopaminergní léčby k nejvýznamnějším terapeutickým přístupům u Parkinsonovy nemoci (PN). Snaha potlačit některé limitace této terapie vede ke zvýšenému zájmu o přístupy jako je adaptivní DBS (aDBS). Stimulace s uzavřenou smyčkou řízená fluktuacemi výkonu v beta pásmu však nemusí být optimální pro všechny pacienty s PN. S cílem nalézt více senzitivní ukazatel než samotnou beta aktivitu byly analyzovány vztahy mezi jednotlivými oscilacemi v kontextu optimální stimulace subthalamického jádra (STN). Vztah fáze beta rytmu a amplitudy vysokofrekvenčních oscilací se jeví jako vhodný parametr pro cílení stimulace

Intraoperative electrophysiological monitoring determines the final electrode position for pallidal stimulation in dystonia patients

BackgroundBilateral deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an effective treatment for refractory dystonia. Neuroradiological target and stimulation electrode trajectory planning with intraoperative microelectrode recordings (MER) and stimulation are used. With improving neuroradiological techniques, the need for MER is in dispute mainly because of the suspected risk of hemorrhage and the impact on clinical post DBS outcome.ObjectiveThe aim of the study is to compare the preplanned GPi electrode trajectories with final trajectories selected for electrode implantation after electrophysiological monitoring and to discuss the factors potentially responsible for differences between preplanned and final trajectories. Finally, the potential association between the final trajectory selected for electrode implantation and clinical outcome will be analyzed.MethodsForty patients underwent bilateral GPi DBS (right-sided implants first) for refractory dystonia. The relationship between preplanned and final trajectories (MicroDrive system) was correlated with patient (gender, age, dystonia type and duration) and surgery characteristics (anesthesia type, postoperative pneumocephalus) and clinical outcome measured using CGI (Clinical Global Impression parameter). The correlation between the preplanned and final trajectories together with CGI was compared between patients 1–20 and 21–40 for the learning curve effect.ResultsThe trajectory selected for definitive electrode implantation matched the preplanned trajectory in 72.5% and 70% on the right and left side respectively; 55% had bilateral definitive electrodes implanted along the preplanned trajectories. Statistical analysis did not confirm any of the studied factors as predictor of the difference between the preplanned and final trajectories. Also no association between CGI and final trajectory selected for electrode implantation in the right/left hemisphere has been proven. The percentages of final electrodes implanted along the preplanned trajectory (the correlation between anatomical planning and intraoperative electrophysiology results) did not differ between patients 1–20 and 21–40. Similarly, there were no statistically significant differences in CGI (clinical outcome) between patients 1–20 and 21–40.ConclusionThe final trajectory selected after electrophysiological study differed from the preplanned trajectory in a significant percentage of patients. No predictor of this difference was identified. The anatomo-electrophysiological difference was not predictive of the clinical outcome (as measured using CGI parameter)

A Unique Mechanochemical Redox Reaction Yielding Nanostructured Double Perovskite Sr2_{2}FeMoO6_{6} With an Extraordinarily High Degree of Anti-Site Disorder

Strontium ferromolybdate, Sr(2)FeMoO(6), is an important member of the family of double perovskites with the possible technological applications in the field of spintronics and solid oxide fuel cells. Its preparation via a multi-step ceramic route or various wet chemistry-based routes is notoriously difficult. The present work demonstrates that Sr(2)FeMoO(6) can be mechanosynthesized at ambient temperature in air directly from its precursors (SrO, α-Fe, MoO(3)) in the form of nanostructured powders, without the need for solvents and/or calcination under controlled oxygen fugacity. The mechanically induced evolution of the Sr(2)FeMoO(6) phase and the far-from-equilibrium structural state of the reaction product are systematically monitored with XRD and a variety of spectroscopic techniques including Raman spectroscopy, (57)Fe Mössbauer spectroscopy, and X-ray photoelectron spectroscopy. The unique extensive oxidation of iron species (Fe(0) → Fe(3+)) with simultaneous reduction of Mo cations (Mo(6+) → Mo(5+)), occuring during the mechanosynthesis of Sr(2)FeMoO(6), is attributed to the mechanically triggered formation of tiny metallic iron nanoparticles in superparamagnetic state with a large reaction surface and a high oxidation affinity, whose steady presence in the reaction mixture of the milled educts initiates/promotes the swift redox reaction. High-resolution transmission electron microscopy observations reveal that the mechanosynthesized Sr(2)FeMoO(6), even after its moderate thermal treatment at 923 K for 30 min in air, exhibits the nanostructured nature with the average particle size of 21(4) nm. At the short-range scale, the nanostructure of the as-prepared Sr(2)FeMoO(6) is characterized by both, the strongly distorted geometry of the constituent FeO(6) octahedra and the extraordinarily high degree of anti-site disorder. The degree of anti-site disorder ASD = 0.5, derived independently from the present experimental XRD, Mössbauer, and SQUID magnetization data, corresponds to the completely random distribution of Fe(3+) and Mo(5+) cations over the sites of octahedral coordination provided by the double perovskite structure. Moreover, the fully anti-site disordered Sr(2)FeMoO(6) nanoparticles exhibit superparamagnetism with the blocking temperature T (B) = 240 K and the deteriorated effective magnetic moment μ = 0.055 μ (B) per formula unit

The effect of deep brain stimulation in Parkinson’s disease reflected in EEG microstates

Abstract Mechanisms of deep brain stimulation (DBS) on cortical networks were explored mainly by fMRI. Advanced analysis of high-density EEG is a source of additional information and may provide clinically useful biomarkers. The presented study evaluates EEG microstates in Parkinson’s disease and the effect of DBS of the subthalamic nucleus (STN). The association between revealed spatiotemporal dynamics of brain networks and changes in oscillatory activity and clinical examination were assessed. Thirty-seven patients with Parkinson’s disease treated by STN-DBS underwent two sessions (OFF and ON stimulation conditions) of resting-state EEG. EEG microstates were analyzed in patient recordings and in a matched healthy control dataset. Microstate parameters were then compared across groups and were correlated with clinical and neuropsychological scores. Of the five revealed microstates, two differed between Parkinson’s disease patients and healthy controls. Another microstate differed between ON and OFF stimulation conditions in the patient group and restored parameters in the ON stimulation state toward to healthy values. The mean beta power of that microstate was the highest in patients during the OFF stimulation condition and the lowest in healthy controls; sources were localized mainly in the supplementary motor area. Changes in microstate parameters correlated with UPDRS and neuropsychological scores. Disease specific alterations in the spatiotemporal dynamics of large-scale brain networks can be described by EEG microstates. The approach can reveal changes reflecting the effect of DBS on PD motor symptoms as well as changes probably related to non-motor symptoms not influenced by DBS

Vztahy mezi oscilacemi a jejich využití u adaptivní hluboké mozkové stimulace

Hluboká mozková stimulace (DBS) patří vedle dopaminergní léčby k nejvýznamnějším terapeutickým přístupům u Parkinsonovy nemoci (PN). Snaha potlačit některé limitace této terapie vede ke zvýšenému zájmu o přístupy jako je adaptivní DBS (aDBS). Stimulace s uzavřenou smyčkou řízená fluktuacemi výkonu v beta pásmu však nemusí být optimální pro všechny pacienty s PN. S cílem nalézt více senzitivní ukazatel než samotnou beta aktivitu byly analyzovány vztahy mezi jednotlivými oscilacemi v kontextu optimální stimulace subthalamického jádra (STN). Vztah fáze beta rytmu a amplitudy vysokofrekvenčních oscilací se jeví jako vhodný parametr pro cílení stimulace

Coupling between beta band and high frequency oscillations as a clinically useful biomarker for DBS

Abstract Beta hypersynchrony was recently introduced into clinical practice in Parkinson’s disease (PD) to identify the best stimulation contacts and for adaptive deep brain stimulation (aDBS) sensing. However, many other oscillopathies accompany the disease, and beta power sensing may not be optimal for all patients. The aim of this work was to study the potential clinical usefulness of beta power phase-amplitude coupling (PAC) with high frequency oscillations (HFOs). Subthalamic nucleus (STN) local field potentials (LFPs) from externalized DBS electrodes were recorded and analyzed in PD patients (n = 19). Beta power and HFOs were evaluated in a resting-state condition; PAC was then studied and compared with the electrode contact positions, structural connectivity, and medication state. Beta-HFO PAC (mainly in the 200–500 Hz range) was observed in all subjects. PAC was detectable more specifically in the motor part of the STN compared to beta power and HFOs. Moreover, the presence of PAC better corresponds to the stimulation setup based on the clinical effect. PAC is also sensitive to the laterality of symptoms and dopaminergic therapy, where the greater PAC cluster reflects the more affected side and medication “off” state. Coupling between beta power and HFOs is known to be a correlate of the PD “off” state. Beta-HFO PAC seems to be more sensitive than beta power itself and could be more helpful in the selection of the best clinical stimulation contact and probably also as a potential future input signal for aDBS

Dynamic Formation of Asexual Diploid and Polyploid Lineages: Multilocus Analysis of <em>Cobitis</em> Reveals the Mechanisms Maintaining the Diversity of Clones

<div><p>Given the hybrid genomic constitutions and increased ploidy of many asexual animals, the identification of processes governing the origin and maintenance of clonal diversity provides useful information about the evolutionary consequences of interspecific hybridization, asexuality and polyploidy. In order to understand the processes driving observed diversity of biotypes and clones in the <em>Cobitis taenia</em> hybrid complex, we performed fine-scale genetic analysis of Central European hybrid zone between two sexual species using microsatellite genotyping and mtDNA sequencing. We found that the hybrid zone is populated by an assemblage of clonally (gynogenetically) reproducing di-, tri- and tetraploid hybrid lineages and that successful clones, which are able of spatial expansion, recruit from two ploidy levels, i.e. diploid and triploid. We further compared the distribution of observed estimates of clonal ages to theoretical distributions simulated under various assumptions and showed that new clones are most likely continuously recruited from ancestral populations. This suggests that the clonal diversity is maintained by dynamic equilibrium between origination and extinction of clonal lineages. On the other hand, an interclonal selection is implied by nonrandom spatial distribution of individual clones with respect to the coexisting sexual species. Importantly, there was no evidence for sexually reproducing hybrids or clonally reproducing non-hybrid forms. Together with previous successful laboratory synthesis of clonal <em>Cobitis</em> hybrids, our data thus provide the most compelling evidence that 1) the origin of asexuality is causally linked to interspecific hybridization; 2) successful establishment of clones is not restricted to one specific ploidy level and 3) the initiation of clonality and polyploidy may be dynamic and continuous in asexual complexes.</p> </div

Unrooted statistical parsimony networks of haplotypes belonging to <i>C. taenia</i>-like (T) (upper panel) and <i>C. elongatoides</i>-like (E) (lower panel) clades (sensu [<b>13</b>]).

<p>White circles denote haplotypes found in sexual individuals only, dark grey circles denote those found in hybrids only, and light grey circles denote haplotypes shared by both hybrid and sexual individuals. The sizes of haplotypes are proportional to their frequency. Small blank circles represent missing (unobserved) haplotypes. Newly sequenced haplotypes are in bold. Rectangles delimit the hybrid clades I and II.</p