SLEEPING WHILE AWAKE: A NEUROPHYSIOLOGICAL INVESTIGATION ON SLEEP DURING WAKEFULNESS.

Il sonno e la veglia vengono comunemente considerati come due stati distinti. L\u2019alternanza tra essi, la cui presenza \ue8 stata dimostrata in ogni specie animale studiata fino ad oggi, sembra essere una delle caratteristiche che definisce la nostra vita. Allo stesso tempo, per\uf2, le scoperte portate alla luce negli ultimi decenni hanno offuscato i confini tra questi due stati. I meccanismi del sonno hanno sempre affascinato i neurofisiologi, che infatti, nell\u2019ultimo secolo, li hanno caratterizzati in dettaglio: ora sappiamo che all\u2019attivit\ue0 del sonno sottost\ue0 una specifica attivit\ue0 neuronale chiamata slow oscillation. La slow oscillation, che \ue8 costituita da (ancora una volta) un\u2019alternanza tra periodi di attivit\ue0 e periodi di iperpolarizzazione e silenzio neuronale (OFF-periods), \ue8 la modalit\ue0 base di attivazione del cervello dormiente. Questa alternanza \ue8 dovuta alla tendenza dei neuroni surante lo stato di sonno, di passare ad un periodo silente dopo un\u2019attivazione iniziale, una tendenza a cui viene dato il nome di bistabilit\ue0 neuronale. Molti studi hanno dimostrato come la bistabilit\ue0 neuronale tipica del sonno ed i relativi OFF-periods, possano accadere anche durante la veglia in particolari condizioni patologiche, nelle transizioni del sonno e durante le deprivazioni di sonno. Per questo motivo, se accettassimo che la bistabilit\ue0 neuronale e gli OFF-periods rappresentino una caratteristica fondamentale del sonno, allora dovremmo ammettere che stiamo assistendo ad un cambio di paradigma: da una prospettiva neurofisiologica il sonno pu\uf2 intrudere nella veglia. In questa tesi ho analizzato i nuovi -fluidi- confini tra sonno e veglia e le possibili implicazioni di questi nel problema della persistenza personale attraverso il tempo. Inoltre, ho studiato le implicazioni cliniche dell\u2019intrusione di sonno nella veglia in pazienti con lesioni cerebrali focali di natura ischemica. In particolare, i miei obiettivi sono stati: 1) Dimostrare come la bistabilit\ue0 neuronale possa essere responsabile della perdita di funzione nei pazienti affetti da ischemia cerebrale e come questo potrebbe avere implicazioni nello studio della patofisiologia dell\u2019ischemia cerebrale e nella sua terapia; 2) Stabilire le basi per un modello di sonno locale presente nella vita di tutti i giorni: la sensazione di sonnolenza. Infatti, essa potrebbe riflettere la presenza di porzioni di corteccia in stato di sonno, ma durante lo stato di veglia; 3) Difendere il criterio biologico di identit\ue0, che troverebbe nell\u2019attivit\ue0 cerebrale la continuit\ue0 necessaria al mantenimento della nostra identit\ue0 nel tempo.Sleep and wakefulness are considered two mutually exclusive states. The alternation between those two states seems to be a defining characteristic of our life, a ubiquitous phenomenon demonstrated in every animal species investigated so far. However, during the last decade, advances in neurophysiology have blurred the boundaries between those states. The mechanisms of sleep have always intrigued neurophysiologists and great advances have been made over the last century in understanding them: we now know that the defining characteristic underlying sleep activity is a specific pattern of neuronal activity, namely the slow oscillation. The slow oscillation, which is characterized by the periodic alternation between periods of activity (ON-periods) and periods of hyperpolarization and neuronal silence (OFF-periods) is the default mode of activity of the sleeping cortex. This alternation is due to the tendency of neurons to fall into a silent period after an initial activation; such tendency is known as \u201cbistability\u201d. There is accumulating evidence that sleep-like bistability, and the ensuing OFF-periods, may occur locally in the awake human brain in some pathological conditions, in sleep transition, as well as after sleep deprivation. Therefore, to the extent that bistability and OFF periods represents the basic neuronal features of sleep, a paradigm shift is in place: from a neurophysiological perspective sleep can intrude into wakefulness. In this thesis, I explore the fluid boundaries between sleep and wakefulness and investigate their possible implications on the problem of personal persistence over time. Moreover, I study the clinical implications of the intrusion of sleep into wakefulness in patients with focal brain injury due to stroke. Specifically, I aim to: 1) show how the sleep-like bistability can be responsible for the loss of function in stroke patients. This may have implications for understanding the pathophysiology of stroke and helping to foster recovery; 2) establish the basis for a model of local sleep that might be present in the everyday life, id est the sensation of sleepiness. Indeed, sleepiness could reflect islands of sleep during wakefulness; 3) advocate the biological criterion of identity, in which the continuity necessary for maintaining ourselves over time could be represented by never resting activity in the brain

Analiza pozornosti i stupnja budnosti kao glavnih sastavnih dijelova svjesnosti u odabranim bolestima mozga

Consciousness is a state in which we are able to interact with our external environment. Each person has their own way of interpreting and processing their surrounding environment and will have their own unique responses. The two major components that make up our conscious mind are awareness and vigilance. When one of these is compromised it generally leads to decreased cognitive processing of the external environment which in turn leads to the different disorders of consciousness. The inner workings of consciousness still remain a mystery. However, research is still ongoing into understanding the different correlates, behavioral and neural, that may be involved. In addition, further sleep studies may help bridge the gap between wakefulness and non-wakefulness and thus shed light on altering levels of consciousness. Furthermore, classifying the different types of disorders without any doubt still remains problematic due to the fact that the gold standard for diagnosis is still at bedside. Approximately 40% of patients are misdiagnosed due to the lack of proper imaging techniques. Research into more advanced imaging can open the window to better patient prognosis. It is imperative that these patients are diagnosed correctly as early as possible in order to receive the appropriate care.Svjesnost je stanje u kojem smo u mogućnosti komunicirati sa svojom vanjskom okolinom. Svaka osoba ima svoj način interpretacije i procesiranja svoje okoline te će imati svoje jedinstvene odgovore. Dva sastavna dijela koja tvore naš svjestan um su svjesnost i budnost. Kada je jedan od njih ugrožen, to obično dovodi do smanjenja kognitivne obrade vanjskog okruženja što rezultira različitim poremećajima svijesti. Unutarnji rad svijesti još uvijek ostaje misterij. Međutim, istraživanje je još u tijeku kako bismo razumijeli različite korelacije, ponašanje i neuronske veze, koje mogu biti uključene. Također, daljnje studije spavanja mogu pomoći premostiti razmak između budnosti i ne-budnosti i tako rasvijetliti različite stupnjeve svijesti. Štoviše,razvrstavanje različitih vrsta poremećaja bez ikakve sumnje još uvijek je problematično zbog činjenice da je zlatni standard za dijagnozu još uvijek klinička procjena. Oko 40% pacijenata je pogrešno dijagnosticirano zbog nedostatka odgovarajućih tehnika snimanja. Istraživanje naprednijih tehnika snimanja može otvoriti prozor boljoj prognozi za pacijenta. Imperativ je rana točna dijagnoza pacijenata kako bi u najkraćem mogućem roku dobili odgovarajuću njegu

Analiza pozornosti i stupnja budnosti kao glavnih sastavnih dijelova svjesnosti u odabranim bolestima mozga

Consciousness is a state in which we are able to interact with our external environment. Each person has their own way of interpreting and processing their surrounding environment and will have their own unique responses. The two major components that make up our conscious mind are awareness and vigilance. When one of these is compromised it generally leads to decreased cognitive processing of the external environment which in turn leads to the different disorders of consciousness. The inner workings of consciousness still remain a mystery. However, research is still ongoing into understanding the different correlates, behavioral and neural, that may be involved. In addition, further sleep studies may help bridge the gap between wakefulness and non-wakefulness and thus shed light on altering levels of consciousness. Furthermore, classifying the different types of disorders without any doubt still remains problematic due to the fact that the gold standard for diagnosis is still at bedside. Approximately 40% of patients are misdiagnosed due to the lack of proper imaging techniques. Research into more advanced imaging can open the window to better patient prognosis. It is imperative that these patients are diagnosed correctly as early as possible in order to receive the appropriate care.Svjesnost je stanje u kojem smo u mogućnosti komunicirati sa svojom vanjskom okolinom. Svaka osoba ima svoj način interpretacije i procesiranja svoje okoline te će imati svoje jedinstvene odgovore. Dva sastavna dijela koja tvore naš svjestan um su svjesnost i budnost. Kada je jedan od njih ugrožen, to obično dovodi do smanjenja kognitivne obrade vanjskog okruženja što rezultira različitim poremećajima svijesti. Unutarnji rad svijesti još uvijek ostaje misterij. Međutim, istraživanje je još u tijeku kako bismo razumijeli različite korelacije, ponašanje i neuronske veze, koje mogu biti uključene. Također, daljnje studije spavanja mogu pomoći premostiti razmak između budnosti i ne-budnosti i tako rasvijetliti različite stupnjeve svijesti. Štoviše,razvrstavanje različitih vrsta poremećaja bez ikakve sumnje još uvijek je problematično zbog činjenice da je zlatni standard za dijagnozu još uvijek klinička procjena. Oko 40% pacijenata je pogrešno dijagnosticirano zbog nedostatka odgovarajućih tehnika snimanja. Istraživanje naprednijih tehnika snimanja može otvoriti prozor boljoj prognozi za pacijenta. Imperativ je rana točna dijagnoza pacijenata kako bi u najkraćem mogućem roku dobili odgovarajuću njegu

2022 - The Third Annual Fall Symposium of Student Scholars

The full program book from the Fall 2022 Symposium of Student Scholars, held on November 17, 2022. Includes abstracts from the presentations and posters.https://digitalcommons.kennesaw.edu/sssprograms/1026/thumbnail.jp

Intelligent Biosignal Processing in Wearable and Implantable Sensors

This reprint provides a collection of papers illustrating the state-of-the-art of smart processing of data coming from wearable, implantable or portable sensors. Each paper presents the design, databases used, methodological background, obtained results, and their interpretation for biomedical applications. Revealing examples are brain–machine interfaces for medical rehabilitation, the evaluation of sympathetic nerve activity, a novel automated diagnostic tool based on ECG data to diagnose COVID-19, machine learning-based hypertension risk assessment by means of photoplethysmography and electrocardiography signals, Parkinsonian gait assessment using machine learning tools, thorough analysis of compressive sensing of ECG signals, development of a nanotechnology application for decoding vagus-nerve activity, detection of liver dysfunction using a wearable electronic nose system, prosthetic hand control using surface electromyography, epileptic seizure detection using a CNN, and premature ventricular contraction detection using deep metric learning. Thus, this reprint presents significant clinical applications as well as valuable new research issues, providing current illustrations of this new field of research by addressing the promises, challenges, and hurdles associated with the synergy of biosignal processing and AI through 16 different pertinent studies. Covering a wide range of research and application areas, this book is an excellent resource for researchers, physicians, academics, and PhD or master students working on (bio)signal and image processing, AI, biomaterials, biomechanics, and biotechnology with applications in medicine

Design and Validation of a Wearable, Continuous, and Non-Invasive Hydration Monitor that uses Ultrasonic Pulses to Detect Changes in Tissue Hydration Status

Chronic dehydration is an endemic problem for many population groups. Current methods of monitoring hydration status are invasive, time consuming, cannot be performed while exercising, and require lab resources. A proposed solution is a wearable, continuous, and non-invasive device that uses harm-free ultrasonic pulses to detect changes in tissue hydration status over time. Customer and engineering requirements were defined and used to guide the design process. Literature reviews were performed to identify essential information on dehydration, assess current methods, discover state of the art devices, and describe ultrasonic theory. Market research was performed to identify athletes as the target population group. An adjustable elastic nylon bicep band prototype was manufactured and the integration of more advanced components was proposed. The theoretical signal processing method used to detect hydration status was validated through initial tests with a prototype electrical system composed of a Teensy 3.1 board, two 18 kHz piezoceramic disc elements, and an Arduino/LabVIEW interface. Tests with aluminum, rubber, and sponge materials were performed to compare the signal response to propagation through materials with different acoustic properties and water contents. Finally, tests performed with dehydrated bovine muscle tissue revealed a statistically significant difference between hydrated and dehydrated tissue, a promising indication for future device refinement

Serotonergic psychedelics LSD & psilocybin increase the fractal dimension of cortical brain activity in spatial and temporal domains.

Psychedelic drugs, such as psilocybin and LSD, represent unique tools for researchers investigating the neural origins of consciousness. Currently, the most compelling theories of how psychedelics exert their effects is by increasing the complexity of brain activity and moving the system towards a critical point between order and disorder, creating more dynamic and complex patterns of neural activity. While the concept of criticality is of central importance to this theory, few of the published studies on psychedelics investigate it directly, testing instead related measures such as algorithmic complexity or Shannon entropy. We propose using the fractal dimension of functional activity in the brain as a measure of complexity since findings from physics suggest that as a system organizes towards criticality, it tends to take on a fractal structure. We tested two different measures of fractal dimension, one spatial and one temporal, using fMRI data from volunteers under the influence of both LSD and psilocybin. The first was the fractal dimension of cortical functional connectivity networks and the second was the fractal dimension of BOLD time-series. In addition to the fractal measures, we used a well-established, non-fractal measure of signal complexity and show that they behave similarly. We were able to show that both psychedelic drugs significantly increased the fractal dimension of functional connectivity networks, and that LSD significantly increased the fractal dimension of BOLD signals, with psilocybin showing a non-significant trend in the same direction. With both LSD and psilocybin, we were able to localize changes in the fractal dimension of BOLD signals to brain areas assigned to the dorsal-attenion network. These results show that psychedelic drugs increase the fractal dimension of activity in the brain and we see this as an indicator that the changes in consciousness triggered by psychedelics are associated with evolution towards a critical zone.NIHR Wellcome NSF-NRT MRC Beckley Foundation Alex Mosley Charitable Trust Ad Astria Chandaria Foundation. Neuro-psychoanalysis Foundation Multidisplinary Association for Psychedelic Studies The Heffter Research Institut

Role of water in physics of blood and cerebrospinal fluid

Known physical mechanisms of temperature dependence anomalies of water properties were used to explain the regularities in temperature dependence (TDs) of dynamic, electrical and optical characteristics of biological systems. The dynamics of hydrogen bonds in bulk and hydrated water affected the activation energies TDs of ion currents of voltage-dependent channels that regulate signaling and trophic bonds in the neuropil of the cortical parenchyma. The physics of minimizing the TD of the isobaric heat capacity of water made it possible to explain the stabilization and functional optimization of the thermodynamics of eyeball fluids at 34.5 C and the human brain during sleep at 36.5 C. At these temperatures, the thermoreceptors of the cornea and the cells of the ganglionic layer of the retina, through connections with the suprachiasmatic nucleus and the pineal gland, switch the circadian rhythm from daytime to nighttime. The phylogenesis of the circadian rhythm was reflected in the dependence of the duration of the nighttime sleep of mammals on the diameter of the eyeball and the mass of the pineal gland. The activity of all the nerves of the eyeball led to the division of the nocturnal brain metabolism into NREM and REM phases. These phases correspond to two modes of the glymphatic system - electrochemical and dynamic. The first is responsible for the relaxation processes of synaptic plasticity and chemical neutralization of toxins with the participation of water and melatonin. Rapid eye movement and an increase in cerebral blood flow in the second mode increase water exchange in the parenchyma and flush out toxins into the venous system. Electrophysics of clearance and conductivity of ionic and water channels of membranes of blood vessels and astrocytes modulate oscillations of polarization potentials of water dipole domains in parietal plasma layers of arterioles and capillaries

Two sides of the same coin: adaptation of BCIs to internal states with user-centered design and electrophysiological features

The ideal brain–computer interface (BCI) adapts to the user’s state to enable optimal BCI performance. Two methods of BCI adaptation are commonly applied: User-centered design (UCD) responds to individual user needs and requirements. Passive BCIs can adapt via online analysis of electrophysiological signals. Despite similar goals, these methods are rarely discussed in combination. Hence, we organized a workshop for the 8th International BCI Meeting 2021 to discuss the combined application of both methods. Here we expand upon the workshop by discussing UCD in more detail regarding its utility for end-users as well as non-end-user-based early-stage BCI development. Furthermore, we explore electrophysiology-based online user state adaptation concerning consciousness and pain detection. The integration of the numerous BCI user state adaptation methods into a unified process remains challenging. Yet, further systematic accumulation of specific knowledge about assessment and integration of internal user states bears great potential for BCI optimization

Wearable and Nearable Biosensors and Systems for Healthcare

Biosensors and systems in the form of wearables and “nearables” (i.e., everyday sensorized objects with transmitting capabilities such as smartphones) are rapidly evolving for use in healthcare. Unlike conventional approaches, these technologies can enable seamless or on-demand physiological monitoring, anytime and anywhere. Such monitoring can help transform healthcare from the current reactive, one-size-fits-all, hospital-centered approach into a future proactive, personalized, decentralized structure. Wearable and nearable biosensors and systems have been made possible through integrated innovations in sensor design, electronics, data transmission, power management, and signal processing. Although much progress has been made in this field, many open challenges for the scientific community remain, especially for those applications requiring high accuracy. This book contains the 12 papers that constituted a recent Special Issue of Sensors sharing the same title. The aim of the initiative was to provide a collection of state-of-the-art investigations on wearables and nearables, in order to stimulate technological advances and the use of the technology to benefit healthcare. The topics covered by the book offer both depth and breadth pertaining to wearable and nearable technology. They include new biosensors and data transmission techniques, studies on accelerometers, signal processing, and cardiovascular monitoring, clinical applications, and validation of commercial devices