Sleep manifests itself by the spontaneous emergence of characteristic oscillatory rhythms, which often time-lock and are implicated in memory formation. Here, we analyze a neural mass model of the thalamocortical loop in which the cortical node can generate slow oscillations (approximately 1 Hz) while its thalamic component can generate fast sleep spindles of σ-band activity (12-15 Hz). We study the dynamics for different coupling strengths between the thalamic and cortical nodes, for different conductance values of the thalamic node's potassium leak and hyperpolarization-activated cation-nonselective currents, and for different parameter regimes of the cortical node. The latter are listed as follows: (1) a low activity (DOWN) state with noise-induced, transient excursions into a high activity (UP) state, (2) an adaptation induced slow oscillation limit cycle with alternating UP and DOWN states, and (3) a high activity (UP) state with noise-induced, transient excursions into the low activity (DOWN) state. During UP states, thalamic spindling is abolished or reduced. During DOWN states, the thalamic node generates sleep spindles, which in turn can cause DOWN to UP transitions in the cortical node. Consequently, this leads to spindle-induced UP state transitions in parameter regime (1), thalamic spindles induced in some but not all DOWN states in regime (2), and thalamic spindles following UP to DOWN transitions in regime (3). The spindle-induced σ-band activity in the cortical node, however, is typically the strongest during the UP state, which follows a DOWN state "window of opportunity" for spindling. When the cortical node is parametrized in regime (3), the model well explains the interactions between slow oscillations and sleep spindles observed experimentally during Non-Rapid Eye Movement sleep. The model is computationally efficient and can be integrated into large-scale modeling frameworks to study spatial aspects like sleep wave propagation.

• Publikační typ
• časopisecké články MeSH

Slow-wave synchronous acoustic stimulation is a promising research and therapeutic tool. It is essential to clearly understand the principles of the synchronization methods, to know their performances and limitations, and, most importantly, to have a clear picture of the effect of stimulation on slow-wave activity (SWA). This paper covers the mentioned and currently missing parts of knowledge that are essential for the appropriate development of the method itself and future applications. Artificially streamed real sleep EEG data were used to quantitatively compare the two currently used real-time methods: the phase-locking loop (PLL) and the fixed-step stimulus in our own implementation. The fixed-step stimulation method was concluded to be more reliable and practically applicable compared to the PLL method. The sleep experiment with chronic insomnia patients in our sleep laboratory was analyzed in order to precisely characterize the effect of sound stimulation during deep sleep. We found that there is a significant phase synchronization of delta waves, which were shown to be the most sensitive metric of the effect of acoustic stimulation compared to commonly used averaged signal and power analyses. This finding may change the understanding of the effect and function of the SWA stimulation described in the literature.

• MeSH
• akustická stimulace MeSH
• elektroencefalografie MeSH
• fyzioterapie (techniky) MeSH
• lidé MeSH
• spánek pomalých vln * MeSH
• spánek MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

The dialogue between cortex and hippocampus is known to be crucial for sleep-dependent memory consolidation. During slow wave sleep, memory replay depends on slow oscillation (SO) and spindles in the (neo)cortex and sharp wave-ripples (SWRs) in the hippocampus. The mechanisms underlying interaction of these rhythms are poorly understood. We examined the interaction between cortical SO and hippocampal SWRs in a model of the hippocampo-cortico-thalamic network and compared the results with human intracranial recordings during sleep. We observed that ripple occurrence peaked following the onset of an Up-state of SO and that cortical input to hippocampus was crucial to maintain this relationship. A small fraction of ripples occurred during the Down-state and controlled initiation of the next Up-state. We observed that the effect of ripple depends on its precise timing, which supports the idea that ripples occurring at different phases of SO might serve different functions, particularly in the context of encoding the new and reactivation of the old memories during memory consolidation. The study revealed complex bidirectional interaction of SWRs and SO in which early hippocampal ripples influence transitions to Up-state, while cortical Up-states control occurrence of the later ripples, which in turn influence transition to Down-state.

• MeSH
• elektroencefalografie metody   MeSH
• hipokampus fyziologie   MeSH
• konsolidace paměti fyziologie   MeSH
• lidé MeSH
• neokortex fyziologie   MeSH
• spánek pomalých vln fyziologie   MeSH
• spánek fyziologie   MeSH
• thalamus fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Insomnia is a prevalent and disabling condition whose treatment is not always effective. This pilot study explores the feasibility and effects of closed-loop auditory stimulation (CLAS) as a potential non-invasive intervention to improve sleep, its subjective quality, and memory consolidation in patients with insomnia. A total of 27 patients with chronic insomnia underwent a crossover, sham-controlled study with 2 nights of either CLAS or sham stimulation. Polysomnography was used to record sleep parameters, while questionnaires and a word-pair memory task were administered to assess subjective sleep quality and memory consolidation. The initial analyses included 17 patients who completed the study, met the inclusion criteria, and received CLAS. From those, 10 (58%) received only a small number of stimuli. In the remaining seven (41%) patients with sufficient CLAS, we evaluated the acute and whole-night effect on sleep. CLAS led to a significant immediate increase in slow oscillation (0.5-1 Hz) amplitude and activity, and reduced delta (1-4 Hz) and sigma/sleep spindle (12-15 Hz) activity during slow-wave sleep across the whole night. All these fundamental sleep rhythms are implicated in sleep-dependent memory consolidation. Yet, CLAS did not change sleep-dependent memory consolidation or sleep macrostructure characteristics, number of arousals, or subjective perception of sleep quality. Results showed CLAS to be feasible in patients with insomnia. However, a high variance in the efficacy of our automated stimulation approach suggests that further research is needed to optimise stimulation protocols to better unlock potential CLAS benefits for sleep structure and subjective sleep quality in such clinical settings.

• MeSH
• akustická stimulace * metody   MeSH
• dospělí MeSH
• elektroencefalografie MeSH
• klinické křížové studie * MeSH
• konsolidace paměti fyziologie   MeSH
• kvalita spánku MeSH
• lidé středního věku MeSH
• lidé MeSH
• pilotní projekty MeSH
• polysomnografie * MeSH
• poruchy iniciace a udržování spánku * terapie   patofyziologie   MeSH
• průzkumy a dotazníky MeSH
• spánek pomalých vln * fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

The mechanisms underlying the emergence of seizures are one of the most important unresolved issues in epilepsy research. In this paper, we study how perturbations, exogenous or endogenous, may promote or delay seizure emergence. To this aim, due to the increasingly adopted view of epileptic dynamics in terms of slow-fast systems, we perform a theoretical analysis of the phase response of a generic relaxation oscillator. As relaxation oscillators are effectively bistable systems at the fast time scale, it is intuitive that perturbations of the non-seizing state with a suitable direction and amplitude may cause an immediate transition to seizure. By contrast, and perhaps less intuitively, smaller amplitude perturbations have been found to delay the spontaneous seizure initiation. By studying the isochrons of relaxation oscillators, we show that this is a generic phenomenon, with the size of such delay depending on the slow flow component. Therefore, depending on perturbation amplitudes, frequency and timing, a train of perturbations causes an occurrence increase, decrease or complete suppression of seizures. This dependence lends itself to analysis and mechanistic understanding through methods outlined in this paper. We illustrate this methodology by computing the isochrons, phase response curves and the response to perturbations in several epileptic models possessing different slow vector fields. While our theoretical results are applicable to any planar relaxation oscillator, in the motivating context of epilepsy they elucidate mechanisms of triggering and abating seizures, thus suggesting stimulation strategies with effects ranging from mere delaying to full suppression of seizures.

• MeSH
• biologické modely MeSH
• elektroencefalografie metody   MeSH
• lidé MeSH
• záchvaty patofyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Preictal, ictal, and postictal oscillations in the basal ganglia were analyzed. Five persons with temporal lobe epilepsy who were candidates for surgery had diagonal depth electrodes implanted in the basal ganglia: four of them in the putamen, and one in the pallidum and caudate. Time-frequency and power spectral analyses were used to analyze the EEG. Significant frequency components of 2-10 Hz were consistently observed in the basal ganglia. The frequency of this component slowed during seizures. There was a significant ictal increase in power spectral density in all frequency ranges. The changes in the basal ganglia were consistent while seizure activity spread over the cortex, and partially persisted after the clinical seizure ended. They were inconsistent in the period after seizure onset. Seizures originating in the mesiotemporal structures can affect physiological rhythms in the basal ganglia. The basal ganglia did not generate epileptiform EEG activity. An inhibitory role for the basal ganglia during temporal lobe seizures is suggested.

• MeSH
• analýza hlavních komponent MeSH
• audiovizuální záznam metody   MeSH
• bazální ganglia patofyziologie   MeSH
• biologické hodiny fyziologie   MeSH
• dospělí MeSH
• elektroencefalografie metody   MeSH
• epilepsie temporálního laloku patologie   MeSH
• lidé MeSH
• mapování mozku MeSH
• mladý dospělý MeSH
• mozkové vlny fyziologie   MeSH
• spektrální analýza MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Individual neurons in the medial septum and diagonal band fire in phase with, and appear to act as a 'pacemaker' of, the hippocampal theta rhythm. We investigated the relationships of periodic EEG both among various parts of the septum and with dorsal hippocampal theta recorded concurrently in freely moving rats. Most septal sites showed theta rhythm concurrent with hippocampal theta during locomotion. However, periods with theta at hippocampal but not septal sites were more frequent than the reverse. Theta waves in different parts of the septum were synchronized with each other but medial septal sites showed less frequent theta than other sites. The phase delays between medial and lateral septal sites were < 10 ms, suggesting that the hippocampus does not act as a simple relay between the two. Spectral analysis revealed periods (> 5 s) of theta at hippocampal sites co-occurring with rhythms at multiple septal sites that were slower than theta. Even slower were the 'slow septal waves' (mean 2.7 Hz), which were present in the absence of locomotion and did not 'drive' the hippocampus. Our data suggest that the pacemaker of hippocampal theta may best be thought of as a set of functionally differentiated components rather than as a single homogenous unit.

• MeSH
• akční potenciály MeSH
• biologické hodiny fyziologie   MeSH
• hipokampus fyziologie   MeSH
• krysa rodu rattus MeSH
• mozkové septum fyziologie   MeSH
• potkani Sprague-Dawley MeSH
• theta rytmus EEG MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH

Cirkadiánní rytmy jsou geneticky zakódované rytmicky se střídající změny v organismu působící na mnoha úrovních. Jsou vázány na střídání světla a tmy a řídí individuální cyklus spánku a bdění, příjmu potravy a mnoho dalších procesů. Na jejich narušení se do velké míry podílí dlouhodobé změny v délce spánku, vystavení se umělému světlu po západu slunce, práce ve směnném provozu a mj. stravovací návyky. Narušení cirkadiánních rytmů je považováno za rizikové pro zvýšení chuti k jídlu, hmotnosti a krevního tlaku a pro snížení glukózové tolerance či obranyschopnosti. Jejich důsledkem je vznik metabolických chorob, jež následně napomáhají rozvoji kardiovaskulárních onemocnění či imunitních poruch. Z hlediska patogeneze metabolických chorob se ukazuje vědecky zajímavé a užitečné studium odlišností v nastavení cirkadiánních rytmů, které u lidí nazýváme chronotypy. Tato práce zaměří pozornost na vztah cirkadiánních rytmů, chronotypu a metabolických poruch, jako je obezita, diabetes mellitus 2. typu či metabolický syndrom. Pro evidentní účast množství exogenních vlivů a vysokou komorbiditu zmíněných zdravotních komplikací existuje rozsáhlý prostor pro zefektivnění léčby a prevenci jejich vzniku.

Circadian rhythms are rhythmically repeating and genetically encoded changes in organisms working on many different levels. They are bound to changes in light/dark cycle and control individual sleep-wake cycle, food intake and other processes. Their disruption is mainly caused by long-term changes in the duration of sleep, exposition to artificial light after sunset, shift-work schedule and eating habits. Disruption of circadian rythms is considered as a risk factors for increased appetite, weight, blood pressure and decreased glucose tolerance or immune response, resulting in development of cardiovascular or immunological disorders. From the perspective of pathogenesis of metabolic disorders, individual differences in circadian settings – called chronotypes are a scientifically interesting area for further research. The aim of this work is to study the relationship between circadian rhythms, chronotypes and metabolic disorders, e.g. obesity, diabetes or metabolic syndrome. Due to the obvious influence of exogenous factors and a high comorbidity of the aforementioned health complications, there is a large potential for the improvement of their treatment as well as prevention.

• Klíčová slova
• cirkadiánní oscilace, cirkadiánní preference,
• MeSH
• biologické hodiny fyziologie   MeSH
• chronotyp MeSH
• cirkadiánní rytmus * fyziologie   MeSH
• diabetes mellitus 2. typu etiologie   MeSH
• energetický metabolismus fyziologie   MeSH
• energetický příjem fyziologie   MeSH
• lidé MeSH
• metabolický syndrom * etiologie   MeSH
• nucleus suprachiasmaticus fyziologie   MeSH
• obezita * etiologie   MeSH
• periodicita MeSH
• poruchy cirkadiánního rytmu (spánek) komplikace   MeSH
• přijímání potravy fyziologie   MeSH
• spánková deprivace MeSH
• vliv směnného provozu na zdraví fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH

V kazuistike prezentujeme dlhodobé zlepšenie kompenzácie diabetes mellitus 2. typu po úprave biologických rytmov u pacienta, ktorý pred diagnózou ochorenia tvorivo pracoval prevažne v noci. Pacient mal doposiaľ najvyšší vstupný glykovaný hemoglobín (HbA1c) vyšetrený metódou vyšetrenia podľa Medzinárodnej federácie klinickej chémie a laboratórnej medicíny (IFCC) 19,1 %, resp. Diabetes Control and Complications Trial (DCCT) 19,6 % v našej diabetologickej ambulancii.

In the case report, we present a long-term improvement in type 2 diabetes mellitus compensation after adjusting the biological rhythms in a patient who worked creatively predominantly at night before diagnosis of the disease. The patient had by now the highest input glycated hemoglobin (HbA1c) by the investigated method of examination according to the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) 19,1%, respectively Diabetes Control and Complications Trial (DCCT) 19,6% at our diabetology outpatient department.

• MeSH
• biologické hodiny * genetika   imunologie   účinky léků   MeSH
• diabetes mellitus 2. typu * farmakoterapie   komplikace   prevence a kontrola   MeSH
• glykovaný hemoglobin izolace a purifikace   metabolismus   účinky léků   MeSH
• hyperglykemie * diagnóza   metabolismus   prevence a kontrola   MeSH
• hypoglykemie farmakoterapie   komplikace   prevence a kontrola   MeSH
• krevní glukóza fyziologie   izolace a purifikace   účinky léků   MeSH
• lidé středního věku MeSH
• lidé MeSH
• melatonin izolace a purifikace   metabolismus   MeSH
• pohybová aktivita fyziologie   genetika   účinky léků   MeSH
• poruchy cirkadiánního rytmu (spánek) farmakoterapie   komplikace   prevence a kontrola   MeSH
• statistika jako téma MeSH
• stravovací zvyklosti fyziologie   psychologie   účinky léků   MeSH
• vzdělávání pacientů jako téma MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH