• Publikační typ
• komentáře MeSH
• úvodníky MeSH

Sleep is crucial for maintaining brain homeostasis and individuals with insufficient sleep are prone to more pronounced brain atrophy as compared to sufficiently sleeping peers. Moreover, sleep quality deteriorates with ageing and ageing is also associated with cerebral structural and functional changes, pointing to their mutual bidirectional interrelationship. This study aimed at determining whether sleep quality and age, separately, affect brain integrity and subsequently, whether sleep significantly modulates the effect of age on brain structural and functional integrity. 113 healthy volunteers underwent a multi-modal MRI imaging to extract information about the microstructure and function of major nodes of the ascending reticular activating system. Sleep quality was assessed by self-administered Pittsburgh's sleep quality index (PSQI) questionnaire. Subject were divided into good (global PSQI score <5) and poor (global PSQI score ≥5) sleep quality group. Whereas only borderline correlations were found between sleep quality and MRI metrics, age exhibited widespread correlations with both functional and microstructural MRI metrics. The latter effect was significantly modulated by sleep quality in ascending reticular activating system, hypothalamus, thalamus and also hippocampus in MRI metrics associated with iron load, cellularity and connectivity, mainly in the subgroup with poor sleep quality. Ergo, our results indicate sleep quality as a substantial contributor to both microstructural and functional brain changes in ageing and call for further research in this emerging topic.

• Klíčová slova
• Brain ageing, Diffusion weighted imaging, Multimodal MRI, Relaxometry, Sleep quality,
• Publikační typ
• časopisecké články MeSH

Sleep serves vital physiological functions, yet how sleep in wild animals is influenced by environmental conditions is poorly understood. Here we use high-resolution biologgers to investigate sleep in wild animals over ecologically relevant time scales and quantify variability between individuals under changing conditions. We developed a robust classification for accelerometer data and measured multiple dimensions of sleep in the wild boar (Sus scrofa) over an annual cycle. In support of the hypothesis that environmental conditions determine thermoregulatory challenges, which regulate sleep, we show that sleep quantity, efficiency and quality are reduced on warmer days, sleep is less fragmented in longer and more humid days, while greater snow cover and rainfall promote sleep quality. Importantly, this longest and most detailed analysis of sleep in wild animals to date reveals large inter- and intra-individual variation. Specifically, short-sleepers sleep up to 46% less than long-sleepers but do not compensate for their short sleep through greater plasticity or quality, suggesting they may pay higher costs of sleep deprivation. Given the major role of sleep in health, our results suggest that global warming and the associated increase in extreme climatic events are likely to negatively impact sleep, and consequently health, in wildlife, particularly in nocturnal animals.

• Klíčová slova
• biologging, double-hierarchical generalized mixed-effects models, pace-of-life syndrome, sleep ecology, wild boar,
• MeSH
• roční období MeSH
• spánek * fyziologie   MeSH
• Sus scrofa * fyziologie   MeSH
• životní prostředí MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Objective.This study aims to characterize the time course of impedance, a crucial electrophysiological property of brain tissue, in the human thalamus (THL), amygdala-hippocampus, and posterior hippocampus over an extended period.Approach.Impedance was periodically sampled every 5-15 min over several months in five subjects with drug-resistant epilepsy using an investigational neuromodulation device. Initially, we employed descriptive piecewise and continuous mathematical models to characterize the impedance response for approximately three weeks post-electrode implantation. We then explored the temporal dynamics of impedance during periods when electrical stimulation was temporarily halted, observing a monotonic increase (rebound) in impedance before it stabilized at a higher value. Lastly, we assessed the stability of amplitude and phase over the 24 h impedance cycle throughout the multi-month recording.Main results.Immediately post-implantation, the impedance decreased, reaching a minimum value in all brain regions within approximately two days, and then increased monotonically over about 14 d to a stable value. The models accounted for the variance in short-term impedance changes. Notably, the minimum impedance of the THL in the most epileptogenic hemisphere was significantly lower than in other regions. During the gaps in electrical stimulation, the impedance rebound decreased over time and stabilized around 200 days post-implant, likely indicative of the foreign body response and fibrous tissue encapsulation around the electrodes. The amplitude and phase of the 24 h impedance oscillation remained stable throughout the multi-month recording, with circadian variation in impedance dominating the long-term measures.Significance.Our findings illustrate the complex temporal dynamics of impedance in implanted electrodes and the impact of electrical stimulation. We discuss these dynamics in the context of the known biological foreign body response of the brain to implanted electrodes. The data suggest that the temporal dynamics of impedance are dependent on the anatomical location and tissue epileptogenicity. These insights may offer additional guidance for the delivery of therapeutic stimulation at various time points post-implantation for neuromodulation therapy.

• Klíčová slova
• biological impedance, circadian cycle, epilepsy, implant effect, intracranial monitoring, neuromodulation,
• MeSH
• cizí tělesa * MeSH
• elektrická impedance MeSH
• hluboká mozková stimulace * metody   MeSH
• implantované elektrody MeSH
• lidé MeSH
• mozek fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH

Glymphatic system is an emerging pathway of removing metabolic waste products and toxic solutes from the brain tissue. It is made of a network of perivascular spaces, filled in cerebrospinal and interstitial fluid, encompassing penetrating and pial vessels and communicating with the subarachnoid space. It is separated from vessels by the blood brain barrier and from brain tissue by the endfeet of the astrocytes rich in aquaporin 4, a membrane protein which controls the water flow along the perivascular space. Animal models and magnetic resonance (MR) studies allowed to characterize the glymphatic system function and determine how its impairment could lead to numerous neurological disorders (e.g. Alzheimer's disease, stroke, sleep disturbances, migraine, idiopathic normal pressure hydrocephalus). This review aims to summarize the role of the glymphatic system in the pathophysiology of migraine in order to provide new ways of approaching to this disease and to its therapy.

• Klíčová slova
• CGRP, Cerebrospinal fluid, Cortical spreading depression, DTI-ALPS, Glymphatic system, Headache, Migraine, Neurological disorders, Perivascular space,
• MeSH
• bolesti hlavy metabolismus   MeSH
• glymfatický systém * diagnostické zobrazování   metabolismus   MeSH
• hematoencefalická bariéra metabolismus   MeSH
• migréna * diagnostické zobrazování   metabolismus   MeSH
• mozek diagnostické zobrazování   metabolismus   MeSH
• nemoci nervového systému * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

OBJECTIVE: This study aims to characterize the time course of impedance, a crucial electrophysiological property of brain tissue, in the human thalamus (THL), amygdala-hippocampus (AMG-HPC), and posterior hippocampus (post-HPC) over an extended period. APPROACH: Impedance was periodically sampled every 5-15 minutes over several months in five subjects with drug-resistant epilepsy using an experimental neuromodulation device. Initially, we employed descriptive piecewise and continuous mathematical models to characterize the impedance response for approximately three weeks post-electrode implantation. We then explored the temporal dynamics of impedance during periods when electrical stimulation was temporarily halted, observing a monotonic increase (rebound) in impedance before it stabilized at a higher value. Lastly, we assessed the stability of amplitude and phase over the 24-hour impedance cycle throughout the multi-month recording. MAIN RESULTS: Immediately post-implantation, the impedance decreased, reaching a minimum value in all brain regions within approximately two days, and then increased monotonically over about 14 days to a stable value. The models accounted for the variance in short-term impedance changes. Notably, the minimum impedance of the THL in the most epileptogenic hemisphere was significantly lower than in other regions. During the gaps in electrical stimulation, the impedance rebound decreased over time and stabilized around 200 days post-implant, likely indicative of the foreign body response and fibrous tissue encapsulation around the electrodes. The amplitude and phase of the 24-hour impedance oscillation remained stable throughout the multi-month recording, with circadian variation in impedance dominating the long-term measures. SIGNIFICANCE: Our findings illustrate the complex temporal dynamics of impedance in implanted electrodes and the impact of electrical stimulation. We discuss these dynamics in the context of the known biological foreign body response of the brain to implanted electrodes. The data suggest that the temporal dynamics of impedance are dependent on the anatomical location and tissue epileptogenicity. These insights may offer additional guidance for the delivery of therapeutic stimulation at various time points post-implantation for neuromodulation therapy.

• Klíčová slova
• Biological impedance, Circadian cycle, Epilepsy, Implant effect, Intracranial monitoring, Neuromodulation,
• Publikační typ
• časopisecké články MeSH
• preprinty MeSH

The impedance is a fundamental electrical property of brain tissue, playing a crucial role in shaping the characteristics of local field potentials, the extent of ephaptic coupling, and the volume of tissue activated by externally applied electrical brain stimulation. We tracked brain impedance, sleep-wake behavioral state, and epileptiform activity in five people with epilepsy living in their natural environment using an investigational device. The study identified impedance oscillations that span hours to weeks in the amygdala, hippocampus, and anterior nucleus thalamus. The impedance in these limbic brain regions exhibit multiscale cycles with ultradian (∼1.5-1.7 h), circadian (∼21.6-26.4 h), and infradian (∼20-33 d) periods. The ultradian and circadian period cycles are driven by sleep-wake state transitions between wakefulness, nonrapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep. Limbic brain tissue impedance reaches a minimum value in NREM sleep, intermediate values in REM sleep, and rises through the day during wakefulness, reaching a maximum in the early evening before sleep onset. Infradian (∼20-33 d) impedance cycles were not associated with a distinct behavioral correlate. Brain tissue impedance is known to strongly depend on the extracellular space (ECS) volume, and the findings reported here are consistent with sleep-wake-dependent ECS volume changes recently observed in the rodent cortex related to the brain glymphatic system. We hypothesize that human limbic brain ECS changes during sleep-wake state transitions underlie the observed multiscale impedance cycles. Impedance is a simple electrophysiological biomarker that could prove useful for tracking ECS dynamics in human health, disease, and therapy.SIGNIFICANCE STATEMENT The electrical impedance in limbic brain structures (amygdala, hippocampus, anterior nucleus thalamus) is shown to exhibit oscillations over multiple timescales. We observe that impedance oscillations with ultradian and circadian periodicities are associated with transitions between wakefulness, NREM, and REM sleep states. There are also impedance oscillations spanning multiple weeks that do not have a clear behavioral correlate and whose origin remains unclear. These multiscale impedance oscillations will have an impact on extracellular ionic currents that give rise to local field potentials, ephaptic coupling, and the tissue activated by electrical brain stimulation. The approach for measuring tissue impedance using perturbational electrical currents is an established engineering technique that may be useful for tracking ECS volume.

• Klíčová slova
• brain impedance, circadian rhythm, extracellular space, implantable neural stimulators, long-term data, sleep,
• MeSH
• bdění fyziologie   MeSH
• elektrická impedance MeSH
• hipokampus MeSH
• lidé MeSH
• mozek fyziologie   MeSH
• spánek REM * fyziologie   MeSH
• spánek * fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Human brain aging is characterized by the gradual deterioration of its function and structure, affected by the interplay of a multitude of causal factors. The sleep, a periodically repeating state of reversible unconsciousness characterized by distinct electrical brain activity, is crucial for maintaining brain homeostasis. Indeed, insufficient sleep was associated with accelerated brain atrophy and impaired brain functional connectivity. Concurrently, alteration of sleep-related transient electrical events in senescence was correlated with structural and functional deterioration of brain regions responsible for their generation, implying the interconnectedness of sleep and brain structure. This review discusses currently available data on the link between human brain aging and sleep derived from various neuroimaging and neurophysiological methods. We advocate the notion of a mutual relationship between the sleep structure and age-related alterations of functional and structural brain integrity, pointing out the position of high-quality sleep as a potent preventive factor of early brain aging and neurodegeneration. However, further studies are needed to reveal the causality of the relationship between sleep and brain aging.

• Klíčová slova
• brain aging, functional brain integrity, neuroimaging, sleep, structural brain integrity,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Sleep is essential component of life. Even though the research in this field develops constantly, there are still many aspects of this rather complex process that remains to be fully clarified. One of these aspects, reason why we actually sleep, is perhaps the most crucial. In this mini review we aim to address this question and discuss potential functions of sleep. Many recent scientific papers are currently available that covers similar topic. We tried to summarize these recent findings. There are certainly many ways how to approach this rather complex issue. Our article will specifically focus on role of sleep in neuronal development, synaptic plasticity, memory consolidation or mental health in general. Its role in immune system functioning will also be mentioned. Moreover, we will also consider more general functions of sleep, such as well-being of the organisms or securing survival of the individual. In conclusion, we will highlight possible main function of sleep.

• MeSH
• duševní zdraví * MeSH
• konsolidace paměti MeSH
• lidé MeSH
• mozek imunologie   fyziologie   MeSH
• neuroimunomodulace MeSH
• neuroplasticita MeSH
• spánek * MeSH
• zdravotní stav MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Fluid transport in the perivascular space by the glia-lymphatic (glymphatic) system is important for the removal of solutes from the brain parenchyma, including peptides such as amyloid-beta which are implicated in the pathogenesis of Alzheimer's disease. The glymphatic system is highly active in the sleep state and under the influence of certain of anaesthetics, while it is suppressed in the awake state and by other anaesthetics. Here we investigated whether light sheet fluorescence microscopy of whole optically cleared murine brains was capable of detecting glymphatic differences in sleep- and awake-mimicking anaesthesia, respectively. Using light-sheet imaging of whole brains, we found anaesthetic-dependent cerebrospinal fluid (CSF) influx differences, including reduced tracer influx along tertiary branches of the middle cerebral artery and reduced influx along dorsal and anterior penetrating arterioles, in the awake-mimicking anaesthesia. This study establishes that light sheet microscopy of optically cleared brains is feasible for quantitative analyses and can provide images of the entire glymphatic system in whole brains.

• Klíčová slova
• Glymphatic system, anaesthesia, cerebrospinal fluid, light sheet microscopy, optical tissue clearing,
• MeSH
• anestezie MeSH
• arteria cerebri media fyziologie   MeSH
• arterioly fyziologie   MeSH
• fluorescenční mikroskopie metody   MeSH
• glymfatický systém fyziologie   MeSH
• mozek ultrastruktura   MeSH
• mozkomíšní mok metabolismus   MeSH
• mozkový krevní oběh fyziologie   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• neurozobrazování metody   MeSH
• spánek fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH