Functional neurotoxicity evaluation of noribogaine using video-EEG in cynomolgus monkeys.

PubMed

Authier, Simon; Accardi, Michael V; Paquette, Dominique; Pouliot, Mylène; Arezzo, Joseph; Stubbs, R John; Gerson, Ronald J; Friedhoff, Lawrence T; Weis, Holger

2016-01-01

Continuous video-electroencephalographic (EEG) monitoring remains the gold standard for seizure liability assessments in preclinical drug safety assessments. EEG monitored by telemetry was used to assess the behavioral and EEG effects of noribogaine hydrochloride (noribogaine) in cynomolgus monkeys. Noribogaine is an iboga alkaloid being studied for the treatment of opioid dependence. Six cynomolgus monkeys (3 per gender) were instrumented with EEG telemetry transmitters. Noribogaine was administered to each monkey at both doses (i.e., 160 and 320mg/kg, PO) with an interval between dosing of at least 6days, and the resulting behavioral and EEG effects were evaluated. IV pentylenetetrazol (PTZ), served as a positive control for induced seizures. The administration of noribogaine at either of the doses evaluated was not associated with EEG evidence of seizure or with EEG signals known to be premonitory signs of increased seizure risk (e.g., sharp waves, unusual synchrony, shifts to high-frequency patterns). Noribogaine was associated with a mild reduction in activity levels, increased scratching, licking and chewing, and some degree of poor coordination and related clinical signs. A single monkey exhibited brief myoclonic movements that increased in frequency at the high dose, but which did not appear to generalize, cluster or to be linked with EEG abnormalities. Noribogaine was also associated with emesis and partial anorexia. In contrast, PTZ was associated with substantial pre-ictal EEG patterns including large amplitude, repetitive sharp waves leading to generalized seizures and to typical post-ictal EEG frequency attenuation. EEG patterns were within normal limits following administration of noribogaine at doses up to 320mg/kg with concurrent clinical signs that correlated with plasma exposures and resolved by the end of the monitoring period. PTZ was invariably associated with EEG paroxysmal activity leading to ictal EEG. In the current study, a noribogaine dose of 320mg/kg was considered to be the EEG no observed adverse effect level (NOAEL) in conscious freely moving cynomolgus monkeys. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Study on bayes discriminant analysis of EEG data.

PubMed

Shi, Yuan; He, DanDan; Qin, Fang

2014-01-01

In this paper, we have done Bayes Discriminant analysis to EEG data of experiment objects which are recorded impersonally come up with a relatively accurate method used in feature extraction and classification decisions. In accordance with the strength of α wave, the head electrodes are divided into four species. In use of part of 21 electrodes EEG data of 63 people, we have done Bayes Discriminant analysis to EEG data of six objects. Results In use of part of EEG data of 63 people, we have done Bayes Discriminant analysis, the electrode classification accuracy rates is 64.4%. Bayes Discriminant has higher prediction accuracy, EEG features (mainly αwave) extract more accurate. Bayes Discriminant would be better applied to the feature extraction and classification decisions of EEG data.

Changes of amplitude and topographical characteristics of event-related potentials during the hypnagogic period.

PubMed

Michida, N; Ebata, A; Tanaka, H; Hayashi, M; Hori, T

1999-04-01

In the previous study, during the vertex sharp wave period (hypnagogic EEG stage 4), negative components (N300, N550) were dominant at Fz and Cz in contrast to the positive component (P400) being prominent at the other areas, Pz, Oz, T5 and T6. There is no agreement regarding P400 properties during the hypnagogic period. In this study, using topographic mapping, we found that two negative components (N300, N550) and P400 independently increased their amplitude at the different areas of the scalp as arousal level lowered. The anterior negative components may reflect the information processing related to the K-complex. The P400 may reflect other activities different from the K-complex mechanism or P300 attention mechanisms.

The convulsive and electroencephalographic changes produced by nonpeptidic delta-opioid agonists in rats: comparison with pentylenetetrazol.

PubMed

Jutkiewicz, Emily M; Baladi, Michelle G; Folk, John E; Rice, Kenner C; Woods, James H

2006-06-01

delta-Opioid agonists produce convulsions and antidepressant-like effects in rats. It has been suggested that the antidepressant-like effects are produced through a convulsant mechanism of action either through overt convulsions or nonconvulsive seizures. This study evaluated the convulsive and seizurogenic effects of nonpeptidic delta-opioid agonists at doses that previously were reported to produce antidepressant-like effects. In addition, delta-opioid agonist-induced electroencephalographic (EEG) and behavioral changes were compared with those produced by the chemical convulsant pentylenetetrazol (PTZ). For these studies, EEG changes were recorded using a telemetry system before and after injections of the delta-opioid agonists [(+)-4-[(alphaR)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-methoxyphenyl)methyl]-N,N-diethylbenz (SNC80) and [(+)-4-[alpha(R)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-hydroxyphenyl)methyl]-N,N-diethylbenzamide [(+)-BW373U86]. Acute administration of nonpeptidic delta-opioid agonists produced bilateral ictal and paroxysmal spike and/or sharp wave discharges. delta-Opioid agonists produced brief changes in EEG recordings, and tolerance rapidly developed to these effects; however, PTZ produced longer-lasting EEG changes that were exacerbated after repeated administration. Studies with antiepileptic drugs demonstrated that compounds used to treat absence epilepsy blocked the convulsive effects of nonpeptidic delta-opioid agonists. Overall, these data suggest that delta-opioid agonist-induced EEG changes are not required for the antidepressant-like effects of these compounds and that neural circuitry involved in absence epilepsy may be related to delta-opioid agonist-induced convulsions. In terms of therapeutic development, these data suggest that it may be possible to develop delta-opioid agonists devoid of convulsive properties.

Surface-Wave Pulse Routing around Sharp Right Angles

NASA Astrophysics Data System (ADS)

Gao, Z.; Xu, H.; Gao, F.; Zhang, Y.; Luo, Y.; Zhang, B.

2018-04-01

Surface-plasmon polaritons (SPPs), or localized electromagnetic surface waves propagating on a metal-dielectric interface, are deemed promising information carriers for future subwavelength terahertz and optical photonic circuitry. However, surface waves fundamentally suffer from scattering loss when encountering sharp corners in routing and interconnection of photonic signals. Previous approaches enabling scattering-free surface-wave guidance around sharp corners are limited to either volumetric waveguide environments or extremely narrow bandwidth, being unable to guide a surface-wave pulse (SPP wave packet) on an on-chip platform. Here, in a surface-wave band-gap crystal implemented on a single metal surface, we demonstrate in time-domain routing a surface-wave pulse around multiple sharp right angles without perceptible scattering. Our work not only offers a solution to on-chip surface-wave pulse routing along an arbitrary path, but it also provides spatiotemporal information on the interplay between surface-wave pulses and sharp corners, both of which are desirable in developing high-performance large-scale integrated photonic circuits.

EEG Brain Wave Activity at Rest and during Evoked Attention in Children with Attention-Deficit/Hyperactivity Disorder and Effects of Methylphenidate.

PubMed

Thomas, Bianca Lee; Viljoen, Margaretha

2016-01-01

The aim of this study was to assess baseline EEG brain wave activity in children with attention-deficit/hyperactivity disorder (ADHD) and to examine the effects of evoked attention and methylphenidate on this activity. Children with ADHD (n = 19) were tested while they were stimulant free and during a period in which they were on stimulant (methylphenidate) medication. Control subjects (n = 18) were tested once. EEG brain wave activity was tested both at baseline and during focussed attention. Attention was evoked and EEG brain wave activity was determined by means of the BioGraph Infiniti biofeedback apparatus. The main finding of this study was that control subjects and stimulant-free children with ADHD exhibited the expected reactivity in high alpha-wave activity (11-12 Hz) from baseline to focussed attention; however, methylphenidate appeared to abolish this reactivity. Methylphenidate attenuates the normal cortical response to a cognitive challenge. © 2016 S. Karger AG, Basel.

EEG - A Valuable Biomarker of Brain Injury in Preterm Infants.

PubMed

Pavlidis, Elena; Lloyd, Rhodri O; Boylan, Geraldine B

2017-01-01

This review focuses on the role of electroencephalography (EEG) in monitoring abnormalities of preterm brain function. EEG features of the most common developmental brain injuries in preterm infants, including intraventricular haemorrhage, periventricular leukomalacia, and perinatal asphyxia, are described. We outline the most common EEG biomarkers associated with these injuries, namely seizures, positive rolandic sharp waves, EEG suppression/increased interburst intervals, mechanical delta brush activity, and other deformed EEG waveforms, asymmetries, and asynchronies. The increasing survival rate of preterm infants, in particular those that are very and extremely preterm, has led to a growing demand for a specific and shared characterization of the patterns related to adverse outcome in this unique population. This review includes abundant high-quality images of the EEG patterns seen in premature infants and will provide a valuable resource for everyone working in developmental neuroscience. © 2017 S. Karger AG, Basel.

Bradycardia from flash stimulation.

PubMed

Einspenner, Michael; Brunet, Donald G; Boissé Lomax, Lysa; Spiller, Allison E

2015-12-01

This case study documents a patient who experienced bradycardia brought on by flash stimulation during a routine outpatient EEG recording. The patient had known photosensitive seizures in the past. During this routine EEG, the patient's heart rate dropped to about 12 beats per minute with the EEG displaying slow-delta-frequency waves with no epileptiform spikes or sharp waves. During immediate follow-up, in our emergency department, the patient had a brief asystolic event, followed by bradycardia. Cardiology examinations were normal. We propose that this response was a photic-triggered reflex vasovagal reaction.

Sharp-front wave of strong magnetic field diffusion in solid metal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Bo; Gu, Zhuo-wei; Kan, Ming-xian

When a strong magnetic field diffuses into a solid metal, if the metal's resistance possesses an abrupt rise at some critical temperature and the magnetic field strength is above some critical value, the magnetic field will diffuse into the metal in the form of a sharp-front wave. Formulas for the critical conditions under which a sharp-front magnetic diffusion wave emerges and a formula for the wave-front velocity are derived in this work.

Recurrent seizures during acute acquired toxoplasmosis in an immunocompetent traveller returning from Africa.

PubMed

Beltrame, Anna; Venturini, Sergio; Crichiutti, Giovanni; Meroni, Valeria; Buonfrate, Dora; Bassetti, Matteo

2016-04-01

We report an unusual case of acute acquired toxoplasmosis (AAT) presenting as lymphadenopathy and recurrent seizures in an immunocompetent 15-year-old boy. The patient reported an 18-day vacation to Africa (Ethiopia), 39 days prior to the first seizure. Electroencephalogram (EEG) showed sporadic single-spike or sharp-wave paroxysms and the magnetic resonance imaging (RMI) of the brain was negative. The serology for T. gondii was compatible with an acute infection defined as positive for both toxoplasma-specific IgG and IgM and a low avidity (6 %), confirmed by a reference laboratory. The patient reported other two episodes of seizures, occurring 7 days apart. He was treated with pyrimethamine plus sulfadiazine and leucovorin for 4 weeks, with an improvement of lymphadenitis and normalization of EEG. After 5 months, new seizures were reported and a diagnosis of epilepsy was done. Toxoplasma polymerase chain reaction (PCR) of cerebrospinal fluid (CSF) and blood were negative. A treatment with valproic acid was started, obtaining control of the neurological disease. Awareness of this neurologic manifestation by clinicians is required, also in immunocompetent patients. The relationship between toxoplasmosis and recurrent seizure needs to be investigated by new studies.

Analysis of slow-wave activity and slow-wave oscillations prior to somnambulism.

PubMed

Jaar, Olivier; Pilon, Mathieu; Carrier, Julie; Montplaisir, Jacques; Zadra, Antonio

2010-11-01

STUDY OBJECTIVIES: several studies have investigated slow wave sleep EEG parameters, including slow-wave activity (SWA) in relation to somnambulism, but results have been both inconsistent and contradictory. The first goal of the present study was to conduct a quantitative analysis of sleepwalkers' sleep EEG by studying fluctuations in spectral power for delta (1-4 Hz) and slow delta (0.5-1 Hz) before the onset of somnambulistic episodes. A secondary aim was to detect slow-wave oscillations to examine changes in their amplitude and density prior to behavioral episodes. twenty-two adult sleepwalkers were investigated polysomnographically following 25 h of sleep deprivation. analysis of patients' sleep EEG over the 200 sec prior to the episodes' onset revealed that the episodes were not preceded by a gradual increase in spectral power for either delta or slow delta over frontal, central, or parietal leads. However, time course comparisons revealed significant changes in the density of slow-wave oscillations as well as in very slow oscillations with significant increases occurring during the final 20 sec immediately preceding episode onset. the specificity of these sleep EEG parameters for the occurrence and diagnosis of NREM parasomnias remains to be determined.

High-Definition transcranial direct current stimulation in early onset epileptic encephalopathy: a case study.

PubMed

Meiron, Oded; Gale, Rena; Namestnic, Julia; Bennet-Back, Odeya; David, Jonathan; Gebodh, Nigel; Adair, Devin; Esmaeilpour, Zeinab; Bikson, Marom

2018-01-01

Early onset epileptic encephalopathy is characterized by high daily seizure-frequency, multifocal epileptic discharges, severe psychomotor retardation, and death at infancy. Currently, there are no effective treatments to alleviate seizure frequency and high-voltage epileptic discharges in these catastrophic epilepsy cases. The current study examined the safety and feasibility of High-Definition transcranial direct current stimulation (HD-tDCS) in reducing epileptiform activity in a 30-month-old child suffering from early onset epileptic encephalopathy. HD-tDCS was administered over 10 intervention days spanning two weeks including pre- and post-intervention video-EEG monitoring. There were no serious adverse events or side effects related to the HD-tDCS intervention. Frequency of clinical seizures was not significantly reduced. However, interictal sharp wave amplitudes were significantly lower during the post-intervention period versus baseline. Vital signs and blood biochemistry remained stable throughout the entire study. These exploratory findings support the safety and feasibility of 4 × 1 HD-tDCS in early onset epileptic encephalopathy and provide the first evidence of HD-tDCS effects on paroxysmal EEG features in electroclinical cases under the age of 36 months. Extending HD-tDCS treatment may enhance electrographic findings and clinical effects.

Exploring resting-state EEG brain oscillatory activity in relation to cognitive functioning in multiple sclerosis.

PubMed

Keune, Philipp M; Hansen, Sascha; Weber, Emily; Zapf, Franziska; Habich, Juliane; Muenssinger, Jana; Wolf, Sebastian; Schönenberg, Michael; Oschmann, Patrick

2017-09-01

Neurophysiologic monitoring parameters related to cognition in Multiple Sclerosis (MS) are sparse. Previous work reported an association between magnetoencephalographic (MEG) alpha-1 activity and information processing speed. While this remains to be replicated by more available electroencephalographic (EEG) methods, also other established EEG markers, e.g. the slow-wave/fast-wave ratio (theta/beta ratio), remain to be explored in this context. Performance on standard tests addressing information processing speed and attention (Symbol-Digit Modalities Test, SDMT; Test of Attention Performance, TAP) was examined in relation to resting-state EEG alpha-1 and alpha-2 activity and the theta/beta ratio in 25MS patients. Increased global alpha-1 and alpha-2 activity and an increased frontal theta/beta ratio (pronounced slow-wave relative to fast-wave activity) were associated with lower SDMT processing speed. In an exploratory analysis, clinically impaired attention was associated with a significantly increased frontal theta/beta ratio whereas alpha power did not show sensitivity to clinical impairment. EEG global alpha power and the frontal theta/beta ratio were both associated with attention. The theta/beta ratio involved potential clinical sensitivity. Resting-state EEG recordings can be obtained during the routine clinical process. The examined resting-state measures may represent feasible monitoring parameters in MS. This notion should be explored in future intervention studies. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Analysis of Slow-Wave Activity and Slow-Wave Oscillations Prior to Somnambulism

PubMed Central

Jaar, Olivier; Pilon, Mathieu; Carrier, Julie; Montplaisir, Jacques; Zadra, Antonio

2010-01-01

Study Objectivies: Several studies have investigated slow wave sleep EEG parameters, including slow-wave activity (SWA) in relation to somnambulism, but results have been both inconsistent and contradictory. The first goal of the present study was to conduct a quantitative analysis of sleepwalkers' sleep EEG by studying fluctuations in spectral power for delta (1-4 Hz) and slow delta (0.5-1 Hz) before the onset of somnambulistic episodes. A secondary aim was to detect slow-wave oscillations to examine changes in their amplitude and density prior to behavioral episodes. Participants: Twenty-two adult sleepwalkers were investigated polysomnographically following 25 h of sleep deprivation. Results: Analysis of patients' sleep EEG over the 200 sec prior to the episodes' onset revealed that the episodes were not preceded by a gradual increase in spectral power for either delta or slow delta over frontal, central, or parietal leads. However, time course comparisons revealed significant changes in the density of slow-wave oscillations as well as in very slow oscillations with significant increases occurring during the final 20 sec immediately preceding episode onset. Conclusions: The specificity of these sleep EEG parameters for the occurrence and diagnosis of NREM parasomnias remains to be determined. Citation: Jaar O; Pilon M; Carrier J; Montplaisir J; Zadra A. Analysis of slow-wave activity and slow-wave oscillations prior to somnambulism. SLEEP 2010;33(11):1511-1516. PMID:21102993

Positive temporal sharp waves in preterm infants with and without brain ultrasound lesions.

PubMed

Castro Conde, José Ramón; Martínez, Eduardo Doménech; Campo, Candelaria González; Pérez, Arturo Méndez; McLean, Michael Lee

2004-11-01

Clinical significance of neonatal positive temporal sharp waves (PTS) is controversial. The aim of this work is to study (1) PTS incidence in preterm infants with or without major ultrasound lesion (MUL) per gestational age (GA), and (2) the relationship between PTS in both sleep states and other electroencephalographic (EEG) findings with poor prognoses. 97 preterm infants of <27-36 weeks GA, and 12 full-term healthy infants were presented. Prospective study included (1) neurodevelopmental assessment at 40-42 weeks conceptional age (CA), (2) serial neurosonography, and (3) EEG recording at postnatal week 1, 2, 4 and at 40-42 weeks CA. In 50 neonates without MUL, peak PTS was at 31-32 weeks GA. In 47 neonates with MUL, PTS increased significantly from week 2 after birth, descending at the 4th. Neonates of <33 weeks GA with MUL showed significantly increased PTS at term. A significant relationship was found between PTS and other EEG abnormalities with poor neurologic prognoses. PTS incidence varied with sleep states, being predominant in indeterminate sleep in neonates with MUL. PTS increased significantly in infants with MUL, mainly at week 2 of postnatal life, persisting high until term CA, and correlated with other abnormal EEG findings. PTS are highly sensitive to MUL.

Video-EEG recordings in full-term neonates of diabetic mothers: observational study.

PubMed

Castro Conde, José Ramón; González González, Nieves Luisa; González Barrios, Desiré; González Campo, Candelaria; Suárez Hernández, Yaiza; Sosa Comino, Elena

2013-11-01

To determine whether full-term newborn infants of diabetic mothers (IDM) present immature/disorganised EEG patterns in the immediate neonatal period, and whether there was any relationship with maternal glycaemic control. Cohort study with an incidental sample performed in a tertiary hospital neonatal unit. 23 IDM and 22 healthy newborns born between 2010 and 2013. All underwent video-EEG recording lasting >90 min at 48-72 h of life. We analysed the percentage of indeterminate sleep, transient sharp waves per hour and mature-for-gestational age EEG patterns (discontinuity, maximum duration of interburst interval (IBI), asynchrony, asymmetry, δ brushes, encoches frontales and α/θ rolandic activity). The group of IDM was divided into two subgroups according to maternal HbA1c: (1) HbA1c≥6% and (2) HbA1c<6%. Compared with healthy newborns, IDM presented significantly higher percentage of indeterminate sleep (57% vs 25%; p<0.001), discontinuity (2.5% vs 0%; p=0.044) and δ brushes in the bursts (6% vs 3%; p=0.024); higher duration of IBI (0.3 s vs 0 s; p=0.017); fewer encoches frontales (7/h vs 35/h; p<0.001), reduced θ/α rolandic activity (3/h vs 9/h; p<0.001); and more transient sharp waves (25/h vs 5/h; p<0.001). IDM with maternal HbA1c≥6% showed greater percentage of δ brushes in the burst (14% vs 4%; p=0.007). Full-term IDM newborns showed video-EEG features of abnormal development of brain function. Maternal HbA1c levels<6% during pregnancy could minimise the risk of cerebral dysmaturity.

Electroencephalography in the Diagnosis of Genetic Generalized Epilepsy Syndromes

PubMed Central

Seneviratne, Udaya; Cook, Mark J.; D’Souza, Wendyl Jude

2017-01-01

Genetic generalized epilepsy (GGE) consists of several syndromes diagnosed and classified on the basis of clinical features and electroencephalographic (EEG) abnormalities. The main EEG feature of GGE is bilateral, synchronous, symmetric, and generalized spike-wave complex. Other classic EEG abnormalities are polyspikes, epileptiform K-complexes and sleep spindles, polyspike-wave discharges, occipital intermittent rhythmic delta activity, eye-closure sensitivity, fixation-off sensitivity, and photoparoxysmal response. However, admixed with typical changes, atypical epileptiform discharges are also commonly seen in GGE. There are circadian variations of generalized epileptiform discharges. Sleep, sleep deprivation, hyperventilation, intermittent photic stimulation, eye closure, and fixation-off are often used as activation techniques to increase the diagnostic yield of EEG recordings. Reflex seizure-related EEG abnormalities can be elicited by the use of triggers such as cognitive tasks and pattern stimulation during the EEG recording in selected patients. Distinct electrographic abnormalities to help classification can be identified among different electroclinical syndromes. PMID:28993753

Comparison between psycho-acoustics and physio-acoustic measurement to determine optimum reverberation time of pentatonic angklung music concert hall

NASA Astrophysics Data System (ADS)

Sudarsono, Anugrah S.; Merthayasa, I. G. N.; Suprijanto

2015-09-01

This research tried to compare psycho-acoustics and Physio-acoustic measurement to find the optimum reverberation time of soundfield from angklung music. Psycho-acoustic measurement was conducted using a paired comparison method and Physio-acoustic measurement was conducted with EEG Measurement on T3, T4, FP1, and FP2 measurement points. EEG measurement was conducted with 5 persons. Pentatonic angklung music was used as a stimulus with reverberation time variation. The variation was between 0.8 s - 1.6 s with 0.2 s step. EEG signal was analysed using a Power Spectral Density method on Alpha Wave, High Alpha Wave, and Theta Wave. Psycho-acoustic measurement on 50 persons showed that reverberation time preference of pentatonic angklung music was 1.2 second. The result was similar to Theta Wave measurement on FP2 measurement point. High Alpha wave on T4 measurement gave different results, but had similar patterns with psycho-acoustic measurement

Sleep spindles in humans: insights from intracranial EEG and unit recordings

PubMed Central

Andrillon, Thomas; Nir, Yuval; Staba, Richard J.; Ferrarelli, Fabio; Cirelli, Chiara; Tononi, Giulio; Fried, Itzhak

2012-01-01

Sleep spindles are an electroencephalographic (EEG) hallmark of non-rapid eye movement (NREM) sleep and are believed to mediate many sleep-related functions, from memory consolidation to cortical development. Spindles differ in location, frequency, and association with slow waves, but whether this heterogeneity may reflect different physiological processes and potentially serve different functional roles remains unclear. Here we utilized a unique opportunity to record intracranial depth EEG and single-unit activity in multiple brain regions of neurosurgical patients to better characterize spindle activity in human sleep. We find that spindles occur across multiple neocortical regions, and less frequently also in the parahippocampal gyrus and hippocampus. Most spindles are spatially restricted to specific brain regions. In addition, spindle frequency is topographically organized with a sharp transition around the supplementary motor area between fast (13-15Hz) centroparietal spindles often occurring with slow wave up-states, and slow (9-12Hz) frontal spindles occurring 200ms later on average. Spindle variability across regions may reflect the underlying thalamocortical projections. We also find that during individual spindles, frequency decreases within and between regions. In addition, deeper sleep is associated with a reduction in spindle occurrence and spindle frequency. Frequency changes between regions, during individual spindles, and across sleep may reflect the same phenomenon, the underlying level of thalamocortical hyperpolarization. Finally, during spindles neuronal firing rates are not consistently modulated, although some neurons exhibit phase-locked discharges. Overall, anatomical considerations can account well for regional spindle characteristics, while variable hyperpolarization levels can explain differences in spindle frequency. PMID:22159098

Analysis of EEG Related Saccadic Eye Movement

NASA Astrophysics Data System (ADS)

Funase, Arao; Kuno, Yoshiaki; Okuma, Shigeru; Yagi, Tohru

Our final goal is to establish the model for saccadic eye movement that connects the saccade and the electroencephalogram(EEG). As the first step toward this goal, we recorded and analyzed the saccade-related EEG. In the study recorded in this paper, we tried detecting a certain EEG that is peculiar to the eye movement. In these experiments, each subject was instructed to point their eyes toward visual targets (LEDs) or the direction of the sound sources (buzzers). In the control cases, the EEG was recorded in the case of no eye movemens. As results, in the visual experiments, we found that the potential of EEG changed sharply on the occipital lobe just before eye movement. Furthermore, in the case of the auditory experiments, similar results were observed. In the case of the visual experiments and auditory experiments without eye movement, we could not observed the EEG changed sharply. Moreover, when the subject moved his/her eyes toward a right-side target, a change in EEG potential was found on the right occipital lobe. On the contrary, when the subject moved his/her eyes toward a left-side target, a sharp change in EEG potential was found on the left occipital lobe.

Adolescent Changes in Homeostatic Regulation of EEG Activity in the Delta and Theta Frequency Bands during NREM Sleep

PubMed Central

Campbell, Ian G.; Darchia, Nato; Higgins, Lisa M.; Dykan, Igor V.; Davis, Nicole M.; de Bie, Evan; Feinberg, Irwin

2011-01-01

Study Objectives: Slow wave EEG activity in NREM sleep decreases by more than 60% between ages 10 and 20 years. Slow wave EEG activity also declines across NREM periods (NREMPs) within a night, and this decline is thought to represent the dynamics of sleep homeostasis. We used longitudinal data to determine whether these homeostatic dynamics change across adolescence. Design: All-night sleep EEG was recorded semiannually for 6 years. Setting: EEG was recorded with ambulatory recorders in the subjects' homes. Participants: Sixty-seven subjects in 2 cohorts, one starting at age 9 and one starting at age 12 years. Measurements and Results: For NREM delta (1-4 Hz) and theta (4-8 Hz) EEG, we tested whether the proportion of spectral energy contained in the first NREMP changes with age. We also tested for age changes in the parameters of the process S exponential decline. For both delta and theta, the proportion of energy in the first NREMP declined significantly across ages 9 to 18 years. Process S parameters SWA0 and TWA0, respectively, represent slow wave (delta) activity and theta wave activity at the beginning of the night. SWA0 and TWA0 declined significantly (P < 0.0001) across ages 9 to 18. Conclusions: These declines indicate that the intensity of the homeostatic or restorative processes at the beginning of sleep diminished across adolescence. We propose that this change in sleep regulation is caused by the synaptic pruning that occurs during adolescent brain maturation. Citation: Campbell IG; Darchia N; Higgins LM; Dykan IV; Davis NM; de Bie E; Feinberg I. Adolescent changes in homeostatic regulation of EEG activity in the delta and theta frequency bands during NREM sleep. SLEEP 2011;34(1):83-91. PMID:21203377

Quantitative EEG and its Correlation with Cardiovascular, Cognition and mood State: an Integrated Study in Simulated Microgravity

NASA Astrophysics Data System (ADS)

Zhang, Jianyuan; Hu, Bin; Chen, Wenjuan; Moore, Philip; Xu, Tingting; Dong, Qunxi; Liu, Zhenyu; Luo, Yuejia; Chen, Shanguang

2014-12-01

The focus of the study is the estimation of the effects of microgravity on the central nervous activity and its underlying influencing mechanisms. To validate the microgravity-induced physiological and psychological effects on EEG, quantitative EEG features, cardiovascular indicators, mood state, and cognitive performances data collection was achieved during a 45 day period using a -6°head-down bed rest (HDBR) integrated approach. The results demonstrated significant differences in EEG data, as an increased Theta wave, a decreased Beta wave and a reduced complexity of brain, accompanied with an increased heart rate and pulse rate, decreased positive emotion, and degraded emotion conflict monitoring performance. The canonical correlation analysis (CCA) based cardiovascular and cognitive related EEG model showed the cardiovascular effect on EEG mainly affected bilateral temporal region and the cognitive effect impacted parietal-occipital and frontal regions. The results obtained in the study support the use of an approach which combines a multi-factor influential mechanism hypothesis. The changes in the EEG data may be influenced by both cardiovascular and cognitive effects.

Functional Imaging of Sleep Vertex Sharp Transients

PubMed Central

Stern, John M.; Caporro, Matteo; Haneef, Zulfi; Yeh, Hsiang J.; Buttinelli, Carla; Lenartowicz, Agatha; Mumford, Jeanette A.; Parvizi, Josef; Poldrack, Russell A.

2011-01-01

Objective The vertex sharp transient (VST) is an electroencephalographic (EEG) discharge that is an early marker of non-REM sleep. It has been recognized since the beginning of sleep physiology research, but its source and function remain mostly unexplained. We investigated VST generation using functional MRI (fMRI). Methods Simultaneous EEG and fMRI were recorded from 7 individuals in drowsiness and light sleep. VST occurrences on EEG were modeled with fMRI using an impulse function convolved with a hemodynamic response function to identify cerebral regions correlating to the VSTs. A resulting statistical image was thresholded at Z>2.3. Results Two hundred VSTs were identified. Significantly increased signal was present bilaterally in medial central, lateral precentral, posterior superior temporal, and medial occipital cortex. No regions of decreased signal were present. Conclusion The regions are consistent with electrophysiologic evidence from animal models and functional imaging of human sleep, but the results are specific to VSTs. The regions principally encompass the primary sensorimotor cortical regions for vision, hearing, and touch. Significance The results depict a network comprising the presumed VST generator and its associated regions. The associated regions functional similarity for primary sensation suggests a role for VSTs in sensory experience during sleep. PMID:21310653

Source localization of small sharp spikes: low resolution electromagnetic tomography (LORETA) reveals two distinct cortical sources.

PubMed

Zumsteg, Dominik; Andrade, Danielle M; Wennberg, Richard A

2006-06-01

We have investigated the cortical sources and electroencephalographic (EEG) characteristics of small sharp spikes (SSS) by using statistical non-parametric mapping (SNPM) of low resolution electromagnetic tomography (LORETA). We analyzed 7 SSS patterns (501 individual SSS) in 6 patients who underwent sleep EEG studies with 29 or 23 scalp electrodes. The scalp signals were averaged time-locked to the SSS peak activity and subjected to SNPM of LORETA values. All 7 SSS patterns (mean 72 individual SSS, range 11-200) revealed a very similar and highly characteristic transhemispheric oblique scalp voltage distribution comprising a first negative field maximum over ipsilateral lateral temporal areas, followed by a second negative field maximum over the contralateral subtemporal region approximately 30 ms later. SNPM-LORETA consistently localized the first component into the ipsilateral posterior insular region, and the second component into ipsilateral posterior mesial temporo-occipital structures. SSS comprise an amalgam of two sequential, distinct cortical components, showing a very uniform and peculiar EEG pattern and cortical source solutions. As such, they must be clearly distinguished from interictal epileptiform discharges in patients with epilepsy. The awareness of these peculiar EEG characteristics may increase our ability to differentiate SSS from interictal epileptiform activity. The finding of a posterior insular source might serve as an inspiration for new physiological considerations regarding these enigmatic waveforms.

Temporal lobe deficits in murderers: EEG findings undetected by PET.

PubMed

Gatzke-Kopp, L M; Raine, A; Buchsbaum, M; LaCasse, L

2001-01-01

This study evaluates electroencephalography (EEG) and positron emission tomography (PET) in the same subjects. Fourteen murderers were assessed by using both PET (while they were performing the continuous performance task) and EEG during a resting state. EEG revealed significant increases in slow-wave activity in the temporal, but not frontal, lobe in murderers, in contrast to prior PET findings that showed reduced prefrontal, but not temporal, glucose metabolism. Results suggest that resting EEG shows empirical utility distinct from PET activation findings.

Kohlbergian Cosmic Perspective Responses, EEG Coherence and the TM and TM-Sidhi Programme.

ERIC Educational Resources Information Center

Nidich, Sanford I.; And Others

1983-01-01

This study compared the brain wave activity (EEG) of people who responded to the question "Why be moral?" with answers indicating a belief in the wholeness of man and nature with respondents who did not show a cosmic orientation. Results showed differences in EEG scores between groups. (Author/IS)

Lacosamide and Levetiracetam Have No Effect on Sharp-Wave Ripple Rate.

PubMed

Kudlacek, Jan; Chvojka, Jan; Posusta, Antonin; Kovacova, Lubica; Hong, Seung Bong; Weiss, Shennan; Volna, Kamila; Marusic, Petr; Otahal, Jakub; Jiruska, Premysl

2017-01-01

Pathological high-frequency oscillations are a novel marker used to improve the delineation of epileptogenic tissue and, hence, the outcome of epilepsy surgery. Their practical clinical utilization is curtailed by the inability to discriminate them from physiological oscillations due to frequency overlap. Although it is well documented that pathological HFOs are suppressed by antiepileptic drugs (AEDs), the effect of AEDs on normal HFOs is not well known. In this experimental study, we have explored whether physiological HFOs (sharp-wave ripples) of hippocampal origin respond to AED treatment. The results show that application of a single dose of levetiracetam or lacosamide does not reduce the rate of sharp-wave ripples. In addition, it seems that these new generation drugs do not negatively affect the cellular and network mechanisms involved in sharp-wave ripple generation, which may provide a plausible explanation for the absence of significant negative effects on cognitive functions of these drugs, particularly on memory.

Pulse Wave Amplitude Drops during Sleep are Reliable Surrogate Markers of Changes in Cortical Activity

PubMed Central

Delessert, Alexandre; Espa, Fabrice; Rossetti, Andrea; Lavigne, Gilles; Tafti, Mehdi; Heinzer, Raphael

2010-01-01

Background: During sleep, sudden drops in pulse wave amplitude (PWA) measured by pulse oximetry are commonly associated with simultaneous arousals and are thought to result from autonomic vasoconstriction. In the present study, we determine whether PWA drops were associated with changes in cortical activity as determined by EEG spectral analysis. Methods: A 20% decrease in PWA was chosen as a minimum for a drop. A total of 1085 PWA drops from 10 consecutive sleep recordings were analyzed. EEG spectral analysis was performed over 5 consecutive epochs of 5 seconds: 2 before, 1 during, and 2 after the PWA drop. EEG spectral analysis was performed over delta, theta, alpha, sigma, and beta frequency bands. Within each frequency band, power density was compared across the five 5-sec epochs. Presence or absence of visually scored EEG arousals were adjudicated by an investigator blinded to the PWA signal and considered associated with PWA drop if concomitant. Results: A significant increase in EEG power density in all EEG frequency bands was found during PWA drops (P < 0.001) compared to before and after drop. Even in the absence of visually scored arousals, PWA drops were associated with a significant increase in EEG power density (P < 0.001) in most frequency bands. Conclusions: Drops in PWA are associated with a significant increase in EEG power density, suggesting that these events can be used as a surrogate for changes in cortical activity during sleep. This approach may prove of value in scoring respiratory events on limited-channel (type III) portable monitors. Citation: Delessert A; Espa F; Rossetti A; Lavigne G; Tafti M; Heinzer R. Pulse wave amplitude drops during sleep are reliable surrogate markers of changes in cortical activity. SLEEP 2010;33(12):1687-1692. PMID:21120131

Hippocampal ripples down-regulate synapses.

PubMed

Norimoto, Hiroaki; Makino, Kenichi; Gao, Mengxuan; Shikano, Yu; Okamoto, Kazuki; Ishikawa, Tomoe; Sasaki, Takuya; Hioki, Hiroyuki; Fujisawa, Shigeyoshi; Ikegaya, Yuji

2018-03-30

The specific effects of sleep on synaptic plasticity remain unclear. We report that mouse hippocampal sharp-wave ripple oscillations serve as intrinsic events that trigger long-lasting synaptic depression. Silencing of sharp-wave ripples during slow-wave states prevented the spontaneous down-regulation of net synaptic weights and impaired the learning of new memories. The synaptic down-regulation was dependent on the N -methyl-d-aspartate receptor and selective for a specific input pathway. Thus, our findings are consistent with the role of slow-wave states in refining memory engrams by reducing recent memory-irrelevant neuronal activity and suggest a previously unrecognized function for sharp-wave ripples. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Nonlinear dynamical systems effects of homeopathic remedies on multiscale entropy and correlation dimension of slow wave sleep EEG in young adults with histories of coffee-induced insomnia.

PubMed

Bell, Iris R; Howerter, Amy; Jackson, Nicholas; Aickin, Mikel; Bootzin, Richard R; Brooks, Audrey J

2012-07-01

Investigators of homeopathy have proposed that nonlinear dynamical systems (NDS) and complex systems science offer conceptual and analytic tools for evaluating homeopathic remedy effects. Previous animal studies demonstrate that homeopathic medicines alter delta electroencephalographic (EEG) slow wave sleep. The present study extended findings of remedy-related sleep stage alterations in human subjects by testing the feasibility of using two different NDS analytic approaches to assess remedy effects on human slow wave sleep EEG. Subjects (N=54) were young adult male and female college students with a history of coffee-related insomnia who participated in a larger 4-week study of the polysomnographic effects of homeopathic medicines on home-based all-night sleep recordings. Subjects took one bedtime dose of a homeopathic remedy (Coffea cruda or Nux vomica 30c). We computed multiscale entropy (MSE) and the correlation dimension (Mekler-D2) for stages 3 and 4 slow wave sleep EEG sampled in artifact-free 2-min segments during the first two rapid-eye-movement (REM) cycles for remedy and post-remedy nights, controlling for placebo and post-placebo night effects. MSE results indicate significant, remedy-specific directional effects, especially later in the night (REM cycle 2) (CC: remedy night increases and post-remedy night decreases in MSE at multiple sites for both stages 3 and 4 in both REM cycles; NV: remedy night decreases and post-remedy night increases, mainly in stage 3 REM cycle 2 MSE). D2 analyses yielded more sporadic and inconsistent findings. Homeopathic medicines Coffea cruda and Nux vomica in 30c potencies alter short-term nonlinear dynamic parameters of slow wave sleep EEG in healthy young adults. MSE may provide a more sensitive NDS analytic method than D2 for evaluating homeopathic remedy effects on human sleep EEG patterns. Copyright © 2012 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

Nonlinear Dynamical Systems Effects of Homeopathic Remedies on Multiscale Entropy and Correlation Dimension of Slow Wave Sleep EEG in Young Adults with Histories of Coffee-Induced Insomnia

PubMed Central

Bell, Iris R.; Howerter, Amy; Jackson, Nicholas; Aickin, Mikel; Bootzin, Richard R.; Brooks, Audrey J.

2012-01-01

Background Investigators of homeopathy have proposed that nonlinear dynamical systems (NDS) and complex systems science offer conceptual and analytic tools for evaluating homeopathic remedy effects. Previous animal studies demonstrate that homeopathic medicines alter delta electroencephalographic (EEG) slow wave sleep. The present study extended findings of remedy-related sleep stage alterations in human subjects by testing the feasibility of using two different NDS analytic approaches to assess remedy effects on human slow wave sleep EEG. Methods Subjects (N=54) were young adult male and female college students with a history of coffee-related insomnia who participated in a larger 4-week study of the polysomnographic effects of homeopathic medicines on home-based all-night sleep recordings. Subjects took one bedtime dose of a homeopathic remedy (Coffea cruda or Nux vomica 30c). We computed multiscale entropy (MSE) and the correlation dimension (Mekler-D2) for stage 3 and 4 slow wave sleep EEG sampled in artifact-free 2-minute segments during the first two rapid-eye-movement (REM) cycles for remedy and post-remedy nights, controlling for placebo and post-placebo night effects. Results MSE results indicate significant, remedy-specific directional effects, especially later in the night (REM cycle 2) (CC: remedy night increases and post-remedy night decreases in MSE at multiple sites for both stages 3 and 4 in both REM cycles; NV: remedy night decreases and post-remedy night increases, mainly in stage 3 REM cycle 2 MSE). D2 analyses yielded more sporadic and inconsistent findings. Conclusions Homeopathic medicines Coffea cruda and Nux vomica in 30c potencies alter short-term nonlinear dynamic parameters of slow wave sleep EEG in healthy young adults. MSE may provide a more sensitive NDS analytic method than D2 for evaluating homeopathic remedy effects on human sleep EEG patterns. PMID:22818237

EEG slow waves in traumatic brain injury: Convergent findings in mouse and man.

PubMed

Modarres, Mo; Kuzma, Nicholas N; Kretzmer, Tracy; Pack, Allan I; Lim, Miranda M

2016-07-01

Evidence from previous studies suggests that greater sleep pressure, in the form of EEG-based slow waves, accumulates in specific brain regions that are more active during prior waking experience. We sought to quantify the number and coherence of EEG slow waves in subjects with mild traumatic brain injury (mTBI). We developed a method to automatically detect individual slow waves in each EEG channel, and validated this method using simulated EEG data. We then used this method to quantify EEG-based slow waves during sleep and wake states in both mouse and human subjects with mTBI. A modified coherence index that accounts for information from multiple channels was calculated as a measure of slow wave synchrony. Brain-injured mice showed significantly higher theta:alpha amplitude ratios and significantly more slow waves during spontaneous wakefulness and during prolonged sleep deprivation, compared to sham-injured control mice. Human subjects with mTBI showed significantly higher theta:beta amplitude ratios and significantly more EEG slow waves while awake compared to age-matched control subjects. We then quantified the global coherence index of slow waves across several EEG channels in human subjects. Individuals with mTBI showed significantly less EEG global coherence compared to control subjects while awake, but not during sleep. EEG global coherence was significantly correlated with severity of post-concussive symptoms (as assessed by the Neurobehavioral Symptom Inventory scale). Taken together, our data from both mouse and human studies suggest that EEG slow wave quantity and the global coherence index of slow waves may represent a sensitive marker for the diagnosis and prognosis of mTBI and post-concussive symptoms.

Aspects of Complexity in Sleep Analysis

NASA Astrophysics Data System (ADS)

Leitão, José M. N.; Da Rosa, Agostinho C.

The paper presents a selection of sleep analysis problems where some aspects and concepts of complexity come about. Emphasis is given to the electroencephalogram (EEG) as the most important sleep related variable. The conception of the EEG as a message to be deciphered stresses the importance of the communication and information theories in this field. An optimal detector of K complexes and vertex sharp waves based on a stochastic model of sleep EEG is considered. Besides detecting, the algorithm is also able to follow the evolution of the basic ongoing activity. It is shown that both the ostructure and microstructure of sleep can be described in terms of symbols and interpreted as sentences of a language. Syntactic models and Markov chain representations play in this context an important role.

Low Activity Microstates During Sleep.

PubMed

Miyawaki, Hiroyuki; Billeh, Yazan N; Diba, Kamran

2017-06-01

To better understand the distinct activity patterns of the brain during sleep, we observed and investigated periods of diminished oscillatory and population spiking activity lasting for seconds during non-rapid eye movement (non-REM) sleep, which we call "LOW" activity sleep. We analyzed spiking and local field potential (LFP) activity of hippocampal CA1 region alongside neocortical electroencephalogram (EEG) and electromyogram (EMG) in 19 sessions from four male Long-Evans rats (260-360 g) during natural wake/sleep across the 24-hr cycle as well as data from other brain regions obtained from http://crcns.org.1,2. LOW states lasted longer than OFF/DOWN states and were distinguished by a subset of "LOW-active" cells. LOW activity sleep was preceded and followed by increased sharp-wave ripple activity. We also observed decreased slow-wave activity and sleep spindles in the hippocampal LFP and neocortical EEG upon LOW onset, with a partial rebound immediately after LOW. LOW states demonstrated activity patterns consistent with sleep but frequently transitioned into microarousals and showed EMG and LFP differences from small-amplitude irregular activity during quiet waking. Their likelihood decreased within individual non-REM epochs yet increased over the course of sleep. By analyzing data from the entorhinal cortex of rats,1 as well as the hippocampus, the medial prefrontal cortex, the postsubiculum, and the anterior thalamus of mice,2 obtained from http://crcns.org, we confirmed that LOW states corresponded to markedly diminished activity simultaneously in all of these regions. We propose that LOW states are an important microstate within non-REM sleep that provide respite from high-activity sleep and may serve a restorative function. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

Global Intracellular Slow-Wave Dynamics of the Thalamocortical System

PubMed Central

Sheroziya, Maxim

2014-01-01

It is widely accepted that corticothalamic neurons recruit the thalamus in slow oscillation, but global slow-wave thalamocortical dynamics have never been experimentally shown. We analyzed intracellular activities of neurons either from different cortical areas or from a variety of specific and nonspecific thalamic nuclei in relation to the phase of global EEG signal in ketamine-xylazine anesthetized mice. We found that, on average, slow-wave active states started off within frontal cortical areas as well as higher-order and intralaminar thalamus (posterior and parafascicular nuclei) simultaneously. Then, the leading edge of active states propagated in the anteroposterior/lateral direction over the cortex at ∼40 mm/s. The latest structure we recorded within the slow-wave cycle was the anterior thalamus, which followed active states of the retrosplenial cortex. Active states from different cortical areas tended to terminate simultaneously. Sensory thalamic ventral posterior medial and lateral geniculate nuclei followed cortical active states with major inhibitory and weak tonic-like “modulator” EPSPs. In these nuclei, sharp-rising, large-amplitude EPSPs (“drivers”) were not modulated by cortical slow waves, suggesting their origin in ascending pathways. The thalamic active states in other investigated nuclei were composed of depolarization: some revealing “driver”- and “modulator”-like EPSPs, others showing “modulator”-like EPSPs only. We conclude that sensory thalamic nuclei follow the propagating cortical waves, whereas neurons from higher-order thalamic nuclei display “hub dynamics” and thus may contribute to the generation of cortical slow waves. PMID:24966387

Wavelet analysis of epileptic spikes

NASA Astrophysics Data System (ADS)

Latka, Miroslaw; Was, Ziemowit; Kozik, Andrzej; West, Bruce J.

2003-05-01

Interictal spikes and sharp waves in human EEG are characteristic signatures of epilepsy. These potentials originate as a result of synchronous pathological discharge of many neurons. The reliable detection of such potentials has been the long standing problem in EEG analysis, especially after long-term monitoring became common in investigation of epileptic patients. The traditional definition of a spike is based on its amplitude, duration, sharpness, and emergence from its background. However, spike detection systems built solely around this definition are not reliable due to the presence of numerous transients and artifacts. We use wavelet transform to analyze the properties of EEG manifestations of epilepsy. We demonstrate that the behavior of wavelet transform of epileptic spikes across scales can constitute the foundation of a relatively simple yet effective detection algorithm.

[Predictors of epilepsy in children after ischemic stroke].

PubMed

Lvova, O A; Shalkevich, L V; Dron, A N; Lukaschuk, M Y; Orlova, E A; Gusev, V V; Suleymanova, E V; Sulimov, A V; Kudlatch, A I

To determine clinical/instrumental predictors of symptomatic epilepsy after ischemic stroke in children. One hundred and thirty-six patients, aged 0-15 years, with the diagnosis of ischemic stroke (ICD-10 I63.0-I63.9) were examined. The duration of the study was 18 months - 12 years. Patients were stratified into post-stroke (n=22) and control (n=114) groups, the latter included patients without epilepsy regardless of the presence of convulsive seizures in the acute stage of stroke. Predictors were determined based on EEG and characteristics of convulsive syndrome in the acute stage of stroke. The following prognostic criteria were found: generalized type of seizures, focal type of seizures with secondary generalization, epileptiform (peak and/or peak-wave) activity, focal character of epileptiform activity, generalized type of seizures in the combination with slow wave background activity on EEG, generalized type of seizures in the combination with slow wave activity and disorganized activity on EEG.

Comparison of a single-channel EEG sleep study to polysomnography

PubMed Central

Lucey, Brendan P.; McLeland, Jennifer S.; Toedebusch, Cristina D.; Boyd, Jill; Morris, John C.; Landsness, Eric C.; Yamada, Kelvin; Holtzman, David M.

2016-01-01

Summary An accurate home sleep study to assess electroencephalography (EEG)-based sleep stages and EEG power would be advantageous for both clinical and research purposes, such as for longitudinal studies measuring changes in sleep stages over time. The purpose of this study was to compare sleep scoring of a single-channel EEG recorded simultaneously on the forehead against attended polysomnography. Participants were recruited from both a clinical sleep center and a longitudinal research study investigating cognitively-normal aging and Alzheimer's disease. Analysis for overall epoch-by-epoch agreement found strong and substantial agreement between the single-channel EEG compared to polysomnography (kappa=0.67). Slow wave activity in the frontal regions was also similar when comparing the single-channel EEG device to polysomnography. As expected, stage N1 showed poor agreement (sensitivity 0.2) due to lack of occipital electrodes. Other sleep parameters such as sleep latency and REM onset latency had decreased agreement. Participants with disrupted sleep consolidation, such as from obstructive sleep apnea, also had poor agreement. We suspect that disagreement in sleep parameters between the single-channel EEG and polysomnography is partially due to altered waveform morphology and/or poorer signal quality in the single-channel derivation. Our results show that single-channel EEG provides comparable results to polysomnography in assessing REM, combined stages N2 and N3 sleep, and several other parameters including frontal slow wave activity. The data establish that single-channel EEG can be a useful research tool. PMID:27252090

Mechanisms for Selective Single-Cell Reactivation during Offline Sharp-Wave Ripples and Their Distortion by Fast Ripples.

PubMed

Valero, Manuel; Averkin, Robert G; Fernandez-Lamo, Ivan; Aguilar, Juan; Lopez-Pigozzi, Diego; Brotons-Mas, Jorge R; Cid, Elena; Tamas, Gabor; Menendez de la Prida, Liset

2017-06-21

Memory traces are reactivated selectively during sharp-wave ripples. The mechanisms of selective reactivation, and how degraded reactivation affects memory, are poorly understood. We evaluated hippocampal single-cell activity during physiological and pathological sharp-wave ripples using juxtacellular and intracellular recordings in normal and epileptic rats with different memory abilities. CA1 pyramidal cells participate selectively during physiological events but fired together during epileptic fast ripples. We found that firing selectivity was dominated by an event- and cell-specific synaptic drive, modulated in single cells by changes in the excitatory/inhibitory ratio measured intracellularly. This mechanism collapses during pathological fast ripples to exacerbate and randomize neuronal firing. Acute administration of a use- and cell-type-dependent sodium channel blocker reduced neuronal collapse and randomness and improved recall in epileptic rats. We propose that cell-specific synaptic inputs govern firing selectivity of CA1 pyramidal cells during sharp-wave ripples. Copyright © 2017 Elsevier Inc. All rights reserved.

Resting EEG deficits in accused murderers with schizophrenia.

PubMed

Schug, Robert A; Yang, Yaling; Raine, Adrian; Han, Chenbo; Liu, Jianghong; Li, Liejia

2011-10-31

Empirical evidence continues to suggest a biologically distinct violent subtype of schizophrenia. The present study examined whether murderers with schizophrenia would demonstrate resting EEG deficits distinguishing them from both non-violent schizophrenia patients and murderers without schizophrenia. Resting EEG data were collected from five diagnostic groups (normal controls, non-murderers with schizophrenia, murderers with schizophrenia, murderers without schizophrenia, and murderers with psychiatric conditions other than schizophrenia) at a brain hospital in Nanjing, China. Murderers with schizophrenia were characterized by increased left-hemispheric fast-wave EEG activity relative to non-violent schizophrenia patients, while non-violent schizophrenia patients instead demonstrated increased diffuse slow-wave activity compared to all other groups. Results are discussed within the framework of a proposed left-hemispheric over-processing hypothesis specific to violent individuals with schizophrenia, involving left hemispheric hyperarousal deficits, which may lead to a homicidally violent schizophrenia outcome. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats☆

PubMed Central

Mohammed, Haitham S.; Fahmy, Heba M.; Radwan, Nasr M.; Elsayed, Anwar A.

2012-01-01

In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested. PMID:25685416

Evaluation of an automated spike-and-wave complex detection algorithm in the EEG from a rat model of absence epilepsy.

PubMed

Bauquier, Sebastien H; Lai, Alan; Jiang, Jonathan L; Sui, Yi; Cook, Mark J

2015-10-01

The aim of this prospective blinded study was to evaluate an automated algorithm for spike-and-wave discharge (SWD) detection applied to EEGs from genetic absence epilepsy rats from Strasbourg (GAERS). Five GAERS underwent four sessions of 20-min EEG recording. Each EEG was manually analyzed for SWDs longer than one second by two investigators and automatically using an algorithm developed in MATLAB®. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the manual (reference) versus the automatic (test) methods. The results showed that the algorithm had specificity, sensitivity, PPV and NPV >94%, comparable to published methods that are based on analyzing EEG changes in the frequency domain. This provides a good alternative as a method designed to mimic human manual marking in the time domain.

Functional imaging of sleep vertex sharp transients.

PubMed

Stern, John M; Caporro, Matteo; Haneef, Zulfi; Yeh, Hsiang J; Buttinelli, Carla; Lenartowicz, Agatha; Mumford, Jeanette A; Parvizi, Josef; Poldrack, Russell A

2011-07-01

The vertex sharp transient (VST) is an electroencephalographic (EEG) discharge that is an early marker of non-REM sleep. It has been recognized since the beginning of sleep physiology research, but its source and function remain mostly unexplained. We investigated VST generation using functional MRI (fMRI). Simultaneous EEG and fMRI were recorded from seven individuals in drowsiness and light sleep. VST occurrences on EEG were modeled with fMRI using an impulse function convolved with a hemodynamic response function to identify cerebral regions correlating to the VSTs. A resulting statistical image was thresholded at Z>2.3. Two hundred VSTs were identified. Significantly increased signal was present bilaterally in medial central, lateral precentral, posterior superior temporal, and medial occipital cortex. No regions of decreased signal were present. The regions are consistent with electrophysiologic evidence from animal models and functional imaging of human sleep, but the results are specific to VSTs. The regions principally encompass the primary sensorimotor cortical regions for vision, hearing, and touch. The results depict a network comprising the presumed VST generator and its associated regions. The associated regions functional similarity for primary sensation suggests a role for VSTs in sensory experience during sleep. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

EEG Functional Connectivity Prior to Sleepwalking: Evidence of Interplay Between Sleep and Wakefulness

PubMed Central

Desjardins, Marie-Ève; Carrier, Julie; Lina, Jean-Marc; Fortin, Maxime; Gosselin, Nadia; Montplaisir, Jacques

2017-01-01

Abstract Study Objectives: Although sleepwalking (somnambulism) affects up to 4% of adults, its pathophysiology remains poorly understood. Sleepwalking can be preceded by fluctuations in slow-wave sleep EEG signals, but the significance of these pre-episode changes remains unknown and methods based on EEG functional connectivity have yet to be used to better comprehend the disorder. Methods: We investigated the sleep EEG of 27 adult sleepwalkers (mean age: 29 ± 7.6 years) who experienced a somnambulistic episode during slow-wave sleep. The 20-second segment of sleep EEG immediately preceding each patient’s episode was compared with the 20-second segment occurring 2 minutes prior to episode onset. Results: Results from spectral analyses revealed increased delta and theta spectral power in the 20 seconds preceding the episodes’ onset as compared to the 20 seconds occurring 2 minutes before the episodes. The imaginary part of the coherence immediately prior to episode onset revealed (1) decreased delta EEG functional connectivity in parietal and occipital regions, (2) increased alpha connectivity over a fronto-parietal network, and (3) increased beta connectivity involving symmetric inter-hemispheric networks implicating frontotemporal, parietal and occipital areas. Conclusions: Taken together, these modifications in EEG functional connectivity suggest that somnambulistic episodes are preceded by brain processes characterized by the co-existence of arousal and deep sleep. PMID:28204773

Modulation of electroencephalograph activity by manual acupuncture stimulation in healthy subjects: An autoregressive spectral analysis

NASA Astrophysics Data System (ADS)

Yi, Guo-Sheng; Wang, Jiang; Deng, Bin; Wei, Xi-Le; Han, Chun-Xiao

2013-02-01

To investigate whether and how manual acupuncture (MA) modulates brain activities, we design an experiment where acupuncture at acupoint ST36 of the right leg is used to obtain electroencephalograph (EEG) signals in healthy subjects. We adopt the autoregressive (AR) Burg method to estimate the power spectrum of EEG signals and analyze the relative powers in delta (0 Hz-4 Hz), theta (4 Hz-8 Hz), alpha (8 Hz-13 Hz), and beta (13 Hz-30 Hz) bands. Our results show that MA at ST36 can significantly increase the EEG slow wave relative power (delta band) and reduce the fast wave relative powers (alpha and beta bands), while there are no statistical differences in theta band relative power between different acupuncture states. In order to quantify the ratio of slow to fast wave EEG activity, we compute the power ratio index. It is found that the MA can significantly increase the power ratio index, especially in frontal and central lobes. All the results highlight the modulation of brain activities with MA and may provide potential help for the clinical use of acupuncture. The proposed quantitative method of acupuncture signals may be further used to make MA more standardized.

Phase-Locked Loop for Precisely Timed Acoustic Stimulation during Sleep

PubMed Central

Santostasi, Giovanni; Malkani, Roneil; Riedner, Brady; Bellesi, Michele; Tononi, Giulio; Paller, Ken A.; Zee, Phyllis C.

2016-01-01

Background A Brain-Computer Interface could potentially enhance the various benefits of sleep. New Method We describe a strategy for enhancing slow-wave sleep (SWS) by stimulating the sleeping brain with periodic acoustic stimuli that produce resonance in the form of enhanced slow-wave activity in the electroencephalogram (EEG). The system delivers each acoustic stimulus at a particular phase of an electrophysiological rhythm using a Phase-Locked Loop (PLL). Results The PLL is computationally economical and well suited to follow and predict the temporal behavior of the EEG during slow-wave sleep. Comparison with Existing Methods Acoustic stimulation methods may be able to enhance SWS without the risks inherent in electrical stimulation or pharmacological methods. The PLL method differs from other acoustic stimulation methods that are based on detecting a single slow wave rather than modeling slow-wave activity over an extended period of time. Conclusions By providing real-time estimates of the phase of ongoing EEG oscillations, the PLL can rapidly adjust to physiological changes, thus opening up new possibilities to study brain dynamics during sleep. Future application of these methods hold promise for enhancing sleep quality and associated daytime behavior and improving physiologic function. PMID:26617321

EEG slow waves in traumatic brain injury: Convergent findings in mouse and man

PubMed Central

Modarres, Mo; Kuzma, Nicholas N.; Kretzmer, Tracy; Pack, Allan I.; Lim, Miranda M.

2016-01-01

Objective Evidence from previous studies suggests that greater sleep pressure, in the form of EEG-based slow waves, accumulates in specific brain regions that are more active during prior waking experience. We sought to quantify the number and coherence of EEG slow waves in subjects with mild traumatic brain injury (mTBI). Methods We developed a method to automatically detect individual slow waves in each EEG channel, and validated this method using simulated EEG data. We then used this method to quantify EEG-based slow waves during sleep and wake states in both mouse and human subjects with mTBI. A modified coherence index that accounts for information from multiple channels was calculated as a measure of slow wave synchrony. Results Brain-injured mice showed significantly higher theta:alpha amplitude ratios and significantly more slow waves during spontaneous wakefulness and during prolonged sleep deprivation, compared to sham-injured control mice. Human subjects with mTBI showed significantly higher theta:beta amplitude ratios and significantly more EEG slow waves while awake compared to age-matched control subjects. We then quantified the global coherence index of slow waves across several EEG channels in human subjects. Individuals with mTBI showed significantly less EEG global coherence compared to control subjects while awake, but not during sleep. EEG global coherence was significantly correlated with severity of post-concussive symptoms (as assessed by the Neurobehavioral Symptom Inventory scale). Conclusion and implications Taken together, our data from both mouse and human studies suggest that EEG slow wave quantity and the global coherence index of slow waves may represent a sensitive marker for the diagnosis and prognosis of mTBI and post-concussive symptoms. PMID:28018987

Different Effects of Sleep Deprivation and Torpor on EEG Slow-Wave Characteristics in Djungarian Hamsters

PubMed Central

Palchykova, S.; Achermann, P.; Tobler, I.; Deboer, T.

2017-01-01

Abstract It has been shown previously in Djungarian hamsters that the initial electroencephalography (EEG) slow-wave activity (power in the 0.5–4.0 Hz band; SWA) in non-rapid eye movement (NREM) sleep following an episode of daily torpor is consistently enhanced, similar to the SWA increase after sleep deprivation (SD). However, it is unknown whether the network mechanisms underlying the SWA increase after torpor and SD are similar. EEG slow waves recorded in the neocortex during sleep reflect synchronized transitions between periods of activity and silence among large neuronal populations. We therefore set out to investigate characteristics of individual cortical EEG slow waves recorded during NREM sleep after 4 h SD and during sleep after emergence from an episode of daily torpor in adult male Djungarian hamsters. We found that during the first hour after both SD and torpor, the SWA increase was associated with an increase in slow-wave incidence and amplitude. However, the slopes of single slow waves during NREM sleep were steeper in the first hour after SD but not after torpor, and, in contrast to sleep after SD, the magnitude of change in slopes after torpor was unrelated to the changes in SWA. Furthermore, slow-wave slopes decreased progressively within the first 2 h after SD, while a progressive increase in slow-wave slopes was apparent during the first 2 h after torpor. The data suggest that prolonged waking and torpor have different effects on cortical network activity underlying slow-wave characteristics, while resulting in a similar homeostatic sleep response of SWA. We suggest that sleep plays an important role in network homeostasis after both waking and torpor, consistent with a recovery function for both states. PMID:28168294

Preoperative EEG predicts memory and selective cognitive functions after temporal lobe surgery.

PubMed Central

Tuunainen, A; Nousiainen, U; Hurskainen, H; Leinonen, E; Pilke, A; Mervaala, E; Vapalahti, M; Partanen, J; Riekkinen, P

1995-01-01

Preoperative and postoperative cognitive and memory functions, psychiatric outcome, and EEGs were evaluated in 32 epileptic patients who underwent temporal lobe surgery. The presence and location of preoperative slow wave focus in routine EEG predicted memory functions of the non-resected side after surgery. Neuropsychological tests of the function of the frontal lobes also showed improvement. Moreover, psychiatric ratings showed that seizure free patients had significantly less affective symptoms postoperatively than those who were still exhibiting seizures. After temporal lobectomies, successful outcome in postoperative memory functions can be achieved in patients with unilateral slow wave activity in preoperative EEGs. This study suggests a new role for routine EEG in preoperative evaluation of patients with temporal lobe epilepsy. PMID:7608663

Interhemispheric differences of the correlation dimension in a human sleep electroencephalogram.

PubMed

Kobayashi, Toshio; Madokoro, Shigeki; Misaki, Kiwamu; Murayama, Jyunichi; Nakagawa, Hiroki; Wada, Yuji

2002-06-01

The interhemispheric differences of the correlation dimension (D2) in the sleep electroencephalogram (EEG) of eight healthy right-handed students was investigated. During slow wave sleep (SWS) the D2 of the central EEG and the temporal left hemisphere (LH) EEG were significantly higher than those in the right hemisphere (RH) EEG; but during rapid eye movement (REM) sleep, the D2 of the central EEG and the occipital RH EEG were significantly higher. The D2 of EEG in the left temporal site during REM sleep were significantly higher than in the right during the first and third sleep cycles, but these were significantly lower during the fourth and fifth sleep cycles. During REM sleep, temporal brain activity may shift from the LH to the RH as morning approaches.

Mimickers of generalized spike and wave discharges.

PubMed

Azzam, Raed; Bhatt, Amar B

2014-06-01

Overinterpretation of benign EEG variants is a common problem that can lead to the misdiagnosis of epilepsy. We review four normal patterns that mimic generalized spike and wave discharges: phantom spike-and-wave, hyperventilation hypersynchrony, hypnagogic/ hypnopompic hypersynchrony, and mitten patterns.

Electroencephalographic profiles for differentiation of disorders of consciousness

PubMed Central

2013-01-01

Background Electroencephalography (EEG) is best suited for long-term monitoring of brain functions in patients with disorders of consciousness (DOC). Mathematical tools are needed to facilitate efficient interpretation of long-duration sleep-wake EEG recordings. Methods Starting with matching pursuit (MP) decomposition, we automatically detect and parametrize sleep spindles, slow wave activity, K-complexes and alpha, beta and theta waves present in EEG recordings, and automatically construct profiles of their time evolution, relevant to the assessment of residual brain function in patients with DOC. Results Above proposed EEG profiles were computed for 32 patients diagnosed as minimally conscious state (MCS, 20 patients), vegetative state/unresponsive wakefulness syndrome (VS/UWS, 11 patients) and Locked-in Syndrome (LiS, 1 patient). Their interpretation revealed significant correlations between patients’ behavioral diagnosis and: (a) occurrence of sleep EEG patterns including sleep spindles, slow wave activity and light/deep sleep cycles, (b) appearance and variability across time of alpha, beta, and theta rhythms. Discrimination between MCS and VS/UWS based upon prominent features of these profiles classified correctly 87% of cases. Conclusions Proposed EEG profiles offer user-independent, repeatable, comprehensive and continuous representation of relevant EEG characteristics, intended as an aid in differentiation between VS/UWS and MCS states and diagnostic prognosis. To enable further development of this methodology into clinically usable tests, we share user-friendly software for MP decomposition of EEG (http://braintech.pl/svarog) and scripts used for creation of the presented profiles (attached to this article). PMID:24143892

Event-related wave activity in the EEG provides new marker of ADHD.

PubMed

Alexander, David M; Hermens, Daniel F; Keage, Hannah A D; Clark, C Richard; Williams, Leanne M; Kohn, Michael R; Clarke, Simon D; Lamb, Chris; Gordon, Evian

2008-01-01

This study examines the utility of new measures of event-related spatio-temporal waves in the EEG as a marker of ADHD, previously shown to be closely related to the P3 ERP in an adult sample. Wave activity in the EEG was assessed during both an auditory Oddball and a visual continuous performance task (CPT) for an ADHD group ranging in age from 6 to 18 years and comprising mostly Combined and Inattentive subtypes, and for an age and gender matched control group. The ADHD subjects had less wave activity at low frequencies ( approximately 1 Hz) during both tasks. For auditory Oddball targets, this effect was shown to be related to smaller P3 ERP amplitudes. During CPT, the approximately 1 Hz wave activity in the ADHD subjects was inversely related to clinical and behavioral measures of hyperactivity and impulsivity. CPT wave activity at approximately 1 Hz was seen to "normalise" following treatment with stimulant medication. The results identify a deficit in low frequency wave activity as a new marker for ADHD associated with levels of hyperactivity and impulsivity. The marker is evident across a range of tasks and may be specific to ADHD. While lower approximately 1 Hz activity partly accounts for reduced P3 ERPs in ADHD, the effect also arises for tasks that do not elicit a P3. Deficits in behavioral inhibition are hypothesized to arise from underlying dysregulation of cortical inhibition.

Postictal psychosis and its electrophysiological correlates in invasive EEG: a case report study and literature review.

PubMed

Kuba, Robert; Brázdil, Milan; Rektor, Ivan

2012-04-01

We identified two patients with medically refractory temporal lobe epilepsy, from whom intracranial EEG recordings were obtained at the time of postictal psychosis. Both patients had mesial temporal epilepsy associated with hippocampal sclerosis. In both patients, the postictal psychosis was associated with a continual "epileptiform" EEG pattern that differed from their interictal and ictal EEG findings (rhythmical slow wave and "abortive" spike-slow wave complex activity in the right hippocampus and lateral temporal cortex in case 1 and a periodic pattern of triphasic waves in the contacts recording activity from the left anterior cingulate gyrus). Some cases of postictal psychosis might be caused by the transient impairment of several limbic system structures due to the "continual epileptiform discharge" in some brain regions. Case 2 is the first report of a patient with TLE in whom psychotic symptoms were associated with the epileptiform impairment of the anterior cingulate gyrus. Copyright © 2012 Elsevier Inc. All rights reserved.

Electroencephalograph (EEG) study on self-contemplating image formation

NASA Astrophysics Data System (ADS)

Meng, Qinglei; Hong, Elliot; Choa, Fow-Sen

2016-05-01

Electroencephalography (EEG) is one of the most widely used electrophysiological monitoring methods and plays a significant role in studies of human brain electrical activities. Default mode network (DMN), is a functional connection of brain regions that are activated while subjects are not in task positive state or not focused on the outside world. In this study, EEG was used for human brain signals recording while all subjects were asked to sit down quietly on a chair with eyes closed and thinking about some parts of their own body, such as left and right hands, left and right ears, lips, nose, and the images of faces that they were familiar with as well as doing some simple mathematical calculation. The time is marker when the image is formed in the subject's mind. By analyzing brain activity maps 300ms right before the time marked instant for each of the 4 wave bands, Delta, Theta, Alpha and Beta waves. We found that for most EEG datasets during this 300ms, Delta wave activity would mostly locate at the frontal lobe or the visual cortex, and the change and movement of activities are slow. Theta wave activity tended to rotate along the edge of cortex either clockwise or counterclockwise. Beta wave behaved like inquiry types of oscillations between any two regions spread over the cortex. Alpha wave activity looks like a mix of the Theta and Beta activities but more close to Theta activity. From the observation we feel that Beta and high Alpha are playing utility role for information inquiry. Theta and low Alpha are likely playing the role of binding and imagination formation in DMN operations.

Quantum neural network-based EEG filtering for a brain-computer interface.

PubMed

Gandhi, Vaibhav; Prasad, Girijesh; Coyle, Damien; Behera, Laxmidhar; McGinnity, Thomas Martin

2014-02-01

A novel neural information processing architecture inspired by quantum mechanics and incorporating the well-known Schrodinger wave equation is proposed in this paper. The proposed architecture referred to as recurrent quantum neural network (RQNN) can characterize a nonstationary stochastic signal as time-varying wave packets. A robust unsupervised learning algorithm enables the RQNN to effectively capture the statistical behavior of the input signal and facilitates the estimation of signal embedded in noise with unknown characteristics. The results from a number of benchmark tests show that simple signals such as dc, staircase dc, and sinusoidal signals embedded within high noise can be accurately filtered and particle swarm optimization can be employed to select model parameters. The RQNN filtering procedure is applied in a two-class motor imagery-based brain-computer interface where the objective was to filter electroencephalogram (EEG) signals before feature extraction and classification to increase signal separability. A two-step inner-outer fivefold cross-validation approach is utilized to select the algorithm parameters subject-specifically for nine subjects. It is shown that the subject-specific RQNN EEG filtering significantly improves brain-computer interface performance compared to using only the raw EEG or Savitzky-Golay filtered EEG across multiple sessions.

Developmental trajectories of EEG sleep slow wave activity as a marker for motor skill development during adolescence: a pilot study.

PubMed

Lustenberger, Caroline; Mouthon, Anne-Laure; Tesler, Noemi; Kurth, Salome; Ringli, Maya; Buchmann, Andreas; Jenni, Oskar G; Huber, Reto

2017-01-01

Reliable markers for brain maturation are important to identify neural deviations that eventually predict the development of mental illnesses. Recent studies have proposed topographical EEG-derived slow wave activity (SWA) during NREM sleep as a mirror of cortical development. However, studies about the longitudinal stability as well as the relationship with behavioral skills are needed before SWA topography may be considered such a reliable marker. We examined six subjects longitudinally (over 5.1 years) using high-density EEG and a visuomotor learning task. All subjects showed a steady increase of SWA at a frontal electrode and a decrease in central electrodes. Despite these large changes in EEG power, SWA topography was relatively stable within each subject during development indicating individual trait-like characteristics. Moreover, the SWA changes in the central cluster were related to the development of specific visuomotor skills. Taken together with the previous work in this domain, our results suggest that EEG sleep SWA represents a marker for motor skill development and further supports the idea that SWA mirrors cortical development during childhood and adolescence. © 2016 Wiley Periodicals, Inc.

Hilbert-Huang Transformation Based Analyses of FP1, FP2, and Fz Electroencephalogram Signals in Alcoholism.

PubMed

Lin, Chin-Feng; Su, Jiun-Yi; Wang, Hao-Min

2015-09-01

Chronic alcoholism may damage the central nervous system, causing imbalance in the excitation-inhibition homeostasis in the cortex, which may lead to hyper-arousal of the central nervous system, and impairments in cognitive function. In this paper, we use the Hilbert-Huang transformation (HHT) method to analyze the electroencephalogram (EEG) signals from control and alcoholic observers who watched two different pictures. We examined the intrinsic mode function (IMF) based energy distribution features of FP1, FP2, and Fz EEG signals in the time and frequency domains for alcoholics. The HHT-based characteristics of the IMFs, the instantaneous frequencies, and the time-frequency-energy distributions of the IMFs of the clinical FP1, FP2, and Fz EEG signals recorded from normal and alcoholic observers who watched two different pictures were analyzed. We observed that the number of peak amplitudes of the alcoholic subjects is larger than that of the control. In addition, the Pearson correlation coefficients of the IMFs, and the energy-IMF distributions of the clinical FP1, FP2, and Fz EEG signals recorded from normal and alcoholic observers were analyzed. The analysis results show that the energy ratios of IMF4, IMF5, and IMF7 waves of the normal observers to the refereed total energy were larger than 10 %, respectively. In addition, the energy ratios of IMF3, IMF4, and IMF5 waves of the alcoholic observers to the refereed total energy were larger than 10 %. The FP1 and FP2 waves of the normal observers, the FP1 and FP2 waves of the alcoholic observers, and the FP1 and Fz waves of the alcoholic observers demonstrated extremely high correlations. On the other hand, the FP1 waves of the normal and alcoholic observers, the FP1 wave of the normal observer and the FP2 wave of the alcoholic observer, the FP1 wave of the normal observer and the Fz wave of the alcoholic observer, the FP2 waves of the normal and alcoholic FP2 observers, and the FP2 wave of the normal observer and the Fz wave of the alcoholic observer demonstrated extremely low correlations. The IMF4 of the FP1 and FP2 signals of the normal observer, and the IMF5 of the FP1 and FP2 signals of the alcoholic observer were correlated. The IMF4 of the FP1 signal of the normal observer and that of the FP2 signal of the alcoholic observer as well as the IMF5 of the FP1 signal of the normal observer and that of the FP2 signal of the alcoholic observer exhibited extremely low correlations. In this manner, our experiment leads to a better understanding of the HHT-based IMFs features of FP1, FP2, and Fz EEG signals in alcoholism. The analysis results show that the energy ratios of the wave of an alcoholic observer to its refereed total energy for IMF4, and IMF5 in the δ band for FP1, FP2, and Fz channels were larger than those of the respective waves of the normal observer. The alcoholic EEG signals constitute more than 1 % of the total energy in the δ wave, and the reaction times were 0_4, 4_8, 8_12, and 12_16 s. For normal EEG signals, more than 1 % of the total energy is distributed in the δ wave, with a reaction time 0 to 4 s. We observed that the alcoholic subject reaction times were slower than those of the normal subjects, and the alcoholic subjects could have experienced a cognitive error. This phenomenon is due to the intoxicated central nervous systems of the alcoholic subjects.

EEG Functional Connectivity Prior to Sleepwalking: Evidence of Interplay Between Sleep and Wakefulness.

PubMed

Desjardins, Marie-Ève; Carrier, Julie; Lina, Jean-Marc; Fortin, Maxime; Gosselin, Nadia; Montplaisir, Jacques; Zadra, Antonio

2017-04-01

Although sleepwalking (somnambulism) affects up to 4% of adults, its pathophysiology remains poorly understood. Sleepwalking can be preceded by fluctuations in slow-wave sleep EEG signals, but the significance of these pre-episode changes remains unknown and methods based on EEG functional connectivity have yet to be used to better comprehend the disorder. We investigated the sleep EEG of 27 adult sleepwalkers (mean age: 29 ± 7.6 years) who experienced a somnambulistic episode during slow-wave sleep. The 20-second segment of sleep EEG immediately preceding each patient's episode was compared with the 20-second segment occurring 2 minutes prior to episode onset. Results from spectral analyses revealed increased delta and theta spectral power in the 20 seconds preceding the episodes' onset as compared to the 20 seconds occurring 2 minutes before the episodes. The imaginary part of the coherence immediately prior to episode onset revealed (1) decreased delta EEG functional connectivity in parietal and occipital regions, (2) increased alpha connectivity over a fronto-parietal network, and (3) increased beta connectivity involving symmetric inter-hemispheric networks implicating frontotemporal, parietal and occipital areas. Taken together, these modifications in EEG functional connectivity suggest that somnambulistic episodes are preceded by brain processes characterized by the co-existence of arousal and deep sleep. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

[Attention deficit hyperactivity disorder treated with scalp acupuncture and EEG biofeedback therapy in children: a randomized controlled trial].

PubMed

He, Cai-Di; Lang, Bo-Xu; Jin, Ling-Qing; Li, Bing

2014-12-01

To compare the difference in clinical efficacy on children attention deficit hyperactivity disorder (ADHD) between the combined therapy of scalp acupuncture and EGG biofeedback and the simple EEG biofeedback therapy so as to search the better therapeutic method for ADHD. One hundred patients were randomized into an observation group and a control group, 50 cases in each one. In the control group, the simple EEG biofeedback therapy was adopted. In the observation group, on the basis of biofeedback therapy, scalp acupuncture was added and applied to Dingzhongxian (MS 5), Dingpangyixian (MS 8), Baihui (GV 20), Sishencong (EX-HN 1), etc. The ten treatments made one session. After four sessions of treatment, FIQ value in Wechsler intelligence scale, CIH score in Conners children behavior questionnaire, the ratio of 0 wave and p wave in EEG, FRCQ and FAQ in the integrated visual and auditory continuous performance test (IVA-CPT) and clinical comprehensive efficacy were observed before and after treatment in the two groups separately. Three cases were dropped out in the observation group and 2 cases were out in the control group. In the two groups, FIQ, FRCQ and FAQ were all increased after treatment (P < 0.01, P < 0.05); the increases in the observation group were much more significant than those in the control group after treatment (all P < 0.05). In the two groups, CIH score and the ratio of 0 wave and p wave were all reduced after treatment (P < 0.01, P < 0.05); the reduction in the observation group were much more apparent as compared with those in the control group (both P< 0.05). The total effective rate was 91.5% (43/47) in the observation group and better than 83. 3% (40/48, P < 0.01) in the control group. The combined therapy of scalp acupuncture and EEG biofeedback achieves the superior efficacy on children ADHD as compared with the simple biofeedback therapy. This combined therapy rapidly relieves the essential symptoms of ADHD and improves EEG waveform in children patients. Importantly, this therapy obtains and consolidates the significant efficacy.

Chess-playing epilepsy: a case report with video-EEG and back averaging.

PubMed

Mann, M W; Gueguen, B; Guillou, S; Debrand, E; Soufflet, C

2004-12-01

A patient suffering from juvenile myoclonic epilepsy experienced myoclonic jerks, fairly regularly, while playing chess. The myoclonus appeared particularly when he had to plan his strategy, to choose between two solutions or while raising the arm to move a chess figure. Video-EEG-polygraphy was performed, with back averaging of the myoclonus registered during a chess match and during neuropsychological testing with Kohs cubes. The EEG spike wave complexes were localised in the fronto-central region. [Published with video sequences].

Scale-Free Brain-Wave Music from Simultaneously EEG and fMRI Recordings

PubMed Central

Lu, Jing; Wu, Dan; Yang, Hua; Luo, Cheng; Li, Chaoyi; Yao, Dezhong

2012-01-01

In the past years, a few methods have been developed to translate human EEG to music. In 2009, PloS One 4 e5915, we developed a method to generate scale-free brainwave music where the amplitude of EEG was translated to music pitch according to the power law followed by both of them, the period of an EEG waveform is translated directly to the duration of a note, and the logarithm of the average power change of EEG is translated to music intensity according to the Fechner's law. In this work, we proposed to adopt simultaneously-recorded fMRI signal to control the intensity of the EEG music, thus an EEG-fMRI music is generated by combining two different and simultaneous brain signals. And most importantly, this approach further realized power law for music intensity as fMRI signal follows it. Thus the EEG-fMRI music makes a step ahead in reflecting the physiological process of the scale-free brain. PMID:23166768

A Study on Analysis of EEG Caused by Grating Stimulation Imaging

NASA Astrophysics Data System (ADS)

Urakawa, Hiroshi; Nishimura, Toshihiro; Tsubai, Masayoshi; Itoh, Kenji

Recently, many researchers have studied a visual perception. Focus is attended to studies of the visual perception phenomenon by using the grating stimulation images. The previous researches have suggested that a subset of retinal ganglion cells responds to motion in the receptive field center, but only if the wider surround moves with a different trajectory. We discuss the function of human retina, and measure and analysis EEG(electroencephalography) of a normal subject who looks on grating stimulation images. We confirmed the visual perception of human by EEG signal analysis. We also have obtained that a sinusoidal grating stimulation was given, asymmetry was observed the α wave element in EEG of the symmetric part in a left hemisphere and a right hemisphere of the brain. Therefore, it is presumed that projected image is even when the still picture is seen and the image projected onto retinas of right and left eyes is not even for the dynamic scene. It evaluated it by taking the envelope curve for the detected α wave, and using the average and standard deviation.

Uppermost synchronized generators of spike-wave activity are localized in limbic cortical areas in late-onset absence status epilepticus.

PubMed

Piros, Palma; Puskas, Szilvia; Emri, Miklos; Opposits, Gabor; Spisak, Tamas; Fekete, Istvan; Clemens, Bela

2014-03-01

Absence status (AS) epilepticus with generalized spike-wave pattern is frequently found in severely ill patients in whom several disease states co-exist. The cortical generators of the ictal EEG pattern and EEG functional connectivity (EEGfC) of this condition are unknown. The present study investigated the localization of the uppermost synchronized generators of spike-wave activity in AS. Seven patients with late-onset AS were investigated by EEG spectral analysis, LORETA (Low Resolution Electromagnetic Tomography) source imaging, and LSC (LORETA Source Correlation) analysis, which estimates cortico-cortical EEGfC among 23 ROIs (regions of interest) in each hemisphere. All the patients showed generalized ictal EEG activity. Maximum Z-scored spectral power was found in the 1-6 Hz and 12-14 Hz frequency bands. LORETA showed that the uppermost synchronized generators of 1-6 Hz band activity were localized in frontal and temporal cortical areas that are parts of the limbic system. For the 12-14 Hz band, abnormally synchronized generators were found in the antero-medial frontal cortex. Unlike the rather stereotyped spectral and LORETA findings, the individual EEGfC patterns were very dissimilar. The findings are discussed in the context of nonconvulsive seizure types and the role of the underlying cortical areas in late-onset AS. The diversity of the EEGfC patterns remains an enigma. Localizing the cortical generators of the EEG patterns contributes to understanding the neurophysiology of the condition. Copyright © 2013 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Focusing optical waves with a rotationally symmetric sharp-edge aperture

NASA Astrophysics Data System (ADS)

Hu, Yanwen; Fu, Shenhe; Li, Zhen; Yin, Hao; Zhou, Jianying; Chen, Zhenqiang

2018-04-01

While there has been various kinds of patterned structures proposed for wave focusing, these patterned structures usually involve complicated lithographic techniques since the element size of the patterned structures should be precisely controlled in microscale or even nanoscale. Here we propose a new and straightforward method for focusing an optical plane wave in free space with a rotationally symmetric sharp-edge aperture. The focusing phenomenon of wave is realized by superposition of a portion of the higher-order symmetric plane waves generated from the sharp edges of the apertures, in contrast to previously focusing techniques which usually depend on a curved phase. We demonstrate both experimentally and theoretically the focusing effect with a series of apertures having different rotational symmetry, and find that the intensity of the hotspots could be controlled by the symmetric strength of the sharp-edge apertures. The presented results would advance the conventional wisdom that light would diffract in all directions and become expanding when it propagates through an aperture. The proposed method is easy to be processed, and might open potential applications in interferometry, image, and superresolution.

Sleep EEG Changes during Adolescence: An Index of a Fundamental Brain Reorganization

ERIC Educational Resources Information Center

Feinberg, Irwin; Campbell, Ian G.

2010-01-01

Delta (1-4 Hz) EEG power in non-rapid eye movement (NREM) sleep declines massively during adolescence. This observation stimulated the hypothesis that during adolescence the human brain undergoes an extensive reorganization driven by synaptic elimination. The parallel declines in synaptic density, delta wave amplitude and cortical metabolic rate…

EEG patterns in theta and gamma frequency range and their probable relation to human voluntary movement organization.

PubMed

Popivanov, D; Mineva, A; Krekule, I

1999-05-21

In experiments with EEG accompanying continuous slow goal-directed voluntary movements we found abrupt short-term transients (STs) of the coefficients of EEG time-varying autoregressive (TVAR) model. The onset of STs indicated (i) a positive EEG wave related to an increase of 3-7 Hz oscillations in time period before the movement start, (ii) synchronization of 35-40 Hz prior to movement start and during the movement when the target is nearly reached. Both these phenomena are expressed predominantly over supplementary motor area, premotor and parietal cortices. These patterns were detected after averaging of EEG segments synchronized to the abrupt changes of the TVAR coefficients computed in the time course of EEG single records. The results are discussed regarding the cognitive aspect of organization of goal-directed movements.

Patient prognosis based on feature extraction, selection and classification of EEG periodic activity.

PubMed

Sánchez-González, Alain; García-Zapirain, Begoña; Maestro Saiz, Iratxe; Yurrebaso Santamaría, Izaskun

2015-01-01

Periodic activity in electroencephalography (PA-EEG) is shown as comprising a series of repetitive wave patterns that may appear in different cerebral regions and are due to many different pathologies. The diagnosis based on PA-EEG is an arduous task for experts in Clinical Neurophysiology, being mainly based on other clinical features of patients. Considering this difficulty in the diagnosis it is also very complicated to establish the prognosis of patients who present PA-EEG. The goal of this paper is to propose a method capable of determining patient prognosis based on characteristics of the PA-EEG activity. The approach, based on a parallel classification architecture and a majority vote system has proven successful by obtaining a success rate of 81.94% in the classification of patient prognosis of our database.

Assessing a novel polymer-wick based electrode for EEG neurophysiological research.

PubMed

Pasion, Rita; Paiva, Tiago O; Pedrosa, Paulo; Gaspar, Hugo; Vasconcelos, Beatriz; Martins, Ana C; Amaral, Maria H; Nóbrega, João M; Páscoa, Ricardo; Fonseca, Carlos; Barbosa, Fernando

2016-07-15

The EEG technique has decades of valid applications in clinical and experimental neurophysiology. EEG equipment and data analysis methods have been characterized by remarkable developments, but the skin-to-electrode signal transfer remains a challenge for EEG recording. A novel quasi-dry system - the polymer wick-based electrode - was developed to overcome the limitations of conventional dry and wet silver/silver-chloride (Ag/AgCl) electrodes for EEG recording. Nine participants completed an auditory oddball protocol with simultaneous EEG acquisition using both the conventional Ag/AgCl and the wick electrodes. Wick system successfully recorded the expected P300 modulation. Standard ERP analysis, residual random noise analysis, and single-trial analysis of the P300 wave were performed in order to compare signal acquired by both electrodes. It was found that the novel wick electrode performed similarly to the conventional Ag/AgCl electrodes. The developed wick electrode appears to be a reliable alternative for EEG research, representing a promising halfway alternative between wet and dry electrodes. Copyright © 2016 Elsevier B.V. All rights reserved.

EEG slow-wave coherence changes in propofol-induced general anesthesia: experiment and theory

PubMed Central

Wang, Kaier; Steyn-Ross, Moira L.; Steyn-Ross, D. A.; Wilson, Marcus T.; Sleigh, Jamie W.

2014-01-01

The electroencephalogram (EEG) patterns recorded during general anesthetic-induced coma are closely similar to those seen during slow-wave sleep, the deepest stage of natural sleep; both states show patterns dominated by large amplitude slow waves. Slow oscillations are believed to be important for memory consolidation during natural sleep. Tracking the emergence of slow-wave oscillations during transition to unconsciousness may help us to identify drug-induced alterations of the underlying brain state, and provide insight into the mechanisms of general anesthesia. Although cellular-based mechanisms have been proposed, the origin of the slow oscillation has not yet been unambiguously established. A recent theoretical study by Steyn-Ross et al. (2013) proposes that the slow oscillation is a network, rather than cellular phenomenon. Modeling anesthesia as a moderate reduction in gap-junction interneuronal coupling, they predict an unconscious state signposted by emergent low-frequency oscillations with chaotic dynamics in space and time. They suggest that anesthetic slow-waves arise from a competitive interaction between symmetry-breaking instabilities in space (Turing) and time (Hopf), modulated by gap-junction coupling strength. A significant prediction of their model is that EEG phase coherence will decrease as the cortex transits from Turing–Hopf balance (wake) to Hopf-dominated chaotic slow-waves (unconsciousness). Here, we investigate changes in phase coherence during induction of general anesthesia. After examining 128-channel EEG traces recorded from five volunteers undergoing propofol anesthesia, we report a significant drop in sub-delta band (0.05–1.5 Hz) slow-wave coherence between frontal, occipital, and frontal–occipital electrode pairs, with the most pronounced wake-vs.-unconscious coherence changes occurring at the frontal cortex. PMID:25400558

Maternal care affects EEG properties of spike-wave seizures (including pre- and post ictal periods) in adult WAG/Rij rats with genetic predisposition to absence epilepsy.

PubMed

Sitnikova, Evgenia; Rutskova, Elizaveta M; Raevsky, Vladimir V

2016-10-01

WAG/Rij rats have a genetic predisposition to absence epilepsy and develop spontaneous spike-wave discharges in EEG during late ontogenesis (SWD, EEG manifestation of absence epilepsy). Changes in an environment during early postnatal ontogenesis can influence the genetically predetermined absence epilepsy. Here we examined the effect of maternal environment during weaning period on the EEG manifestation of absence epilepsy in adulthood. Experiments were performed in the offspring of WAG/Rij and Wistar rats. The newborn pups were fostered to dams of the same (in-fostering) or another strain (cross-fostering). Age-matched control WAG/Rij and Wistar rats were reared by their biological mothers. Absence seizures were uncommon in Wistar and were not aggravated in both in- and cross-fostered groups. In WAG/Rij rats, fewer SWD were found in the cross-fostered as compared to the in-fostered group. The cross-fostered WAG/Rij rats showed higher percentage of short-lasting SWD with duration <2s. The mean frequency of EEG at the beginning of SWD in the cross-fostered WAG/Rij rats was lower than in control (8.82 vs 9.25Hz), but it was higher in a period of 1.5s before and after SWD. It was concluded that a healthier maternal environment is able to alleviate genetically predetermined absence seizures in adulthood through changes in EEG rhythmic activity. Copyright © 2016 Elsevier Inc. All rights reserved.

Juvenile myoclonic epilepsy locus in chromosome 6p21.2-p11: Linkage to convulsions and electroencephalography trait

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, A.W.; Delgado-Escueta, A.V.; Serratosa, J.M.

1995-08-01

Despite affecting 4 million Americans and 100-200 million persons worldwide, the precise molecular mechanisms of human epilepsies remain unknown. Juvenile myoclonic epilepsy (JME) is the most frequent and, hence, most important form of hereditary grand mal epilepsy. In this epilepsy, electroencephalographic (EEG) 15-30 Hz multispikes produce myoclonic and tonic-clonic convulsions beginning at 8-20 years of age. Moreover, EEG 3.5-6 Hz multispike wave complexes appear in clinically asymptomatic family members. We first studied 38 members of a four-generation LA-Belize family with classical JME but with no pyknoleptic absences. Five living members had JME; four clinically asymptomatic members had EEG multispike wavemore » complexes. Pairwise analysis tightly linked microsatellites centromeric to HLA, namely D6S272 (peak lod score [Z{sub max}]=3.564-3.560 at male-female recombination [{theta}{sub m=f}]=0-0.001) and D6S257 (Z{sub max}=3.672-3.6667 at {theta}{sub m=f}=0-0.001), spanning 7 cM, to convulsive seizures and EEG multispike wave complexes. A recombination between D6S276 and D6S273 in one affected member placed the JME locus within or below HLA. Pairwise, multipoint, and recombination analyses in this large family independently proved that a JME gene is located in chromsome 6p, centromeric to HLA. We next screened, with the same chromosome 6p21.2-p11 short tandem-repeat polymorphic markers, seven multiplex pedigrees with classic JME. When lod scores for small multiplex families are added to lod scores of the LA-Belize pedigree, Z{sub max} values for D6S294 and D6S257 are >7 ({theta}{sub m=f}=0.000). Our results prove that in chromosome 6p21.2-p11 an epilepsy locus exists whose phenotype consists of classic JME with convulsions and/or EEG rapid multispike wave complexes. 31 refs., 6 figs., 4 tabs.« less

The additional lateralizing and localizing value of the postictal EEG in frontal lobe epilepsy.

PubMed

Whitehead, Kimberley; Gollwitzer, Stephanie; Millward, Helen; Wehner, Tim; Scott, Catherine; Diehl, Beate

2016-03-01

The aim of this study was to describe the additional lateralizing and localizing value of the postictal EEG in frontal lobe epilepsy (FLE). The ictal EEG in FLE is frequently challenging to localize. We identified patients investigated for epilepsy surgery with unilateral FLE based on consistent semiology, a clear lesion and/or with frontal onset on intracranial EEG. A one hour section of postictal EEG was analyzed by two raters for new or activated EEG features and it was assessed whether these features offered additional information when compared to the ictal EEG. Postictal features assessed included asymmetrical return of the posterior dominant rhythm and potentiated lateralized or regional frontal slowing, spikes or sharp waves. Thirty-eight patients were included who had a combined total of ninety-six seizures. 47/96 (49%) postictal periods contained correctly lateralizing or localizing information. The sensitivity for asymmetrical return of the posterior dominant rhythm was 24%. The sensitivity for regional frontal slow and frontal spikes was 23% and 20% respectively. Further analysis showed that in 14/38 (39%) patients, at least one seizure with an unhelpful ictal EEG was followed by postictal EEG features that added new localizing or lateralizing information. A subgroup of 11 patients who were ⩾1 year seizure-free (ILAE class 1) and thus classified as having a 'gold-standard' FLE diagnosis were analyzed separately and it was found that 14/30 of their seizures (47%) had extra postictal information. The new postictal information was always concordant with the ultimate diagnosis, except for asymmetric postictal return of background activity ipsilateral to the epileptogenic zone in three patients. This study shows that a close examination of the postictal EEG can offer additional information which can contribute to the identification of a potentially resectable epileptogenic zone. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Interrater agreement in the interpretation of neonatal electroencephalography in hypoxic-ischemic encephalopathy.

PubMed

Wusthoff, Courtney J; Sullivan, Joseph; Glass, Hannah C; Shellhaas, Renée A; Abend, Nicholas S; Chang, Taeun; Tsuchida, Tammy N

2017-03-01

Research using neonatal electroencephalography (EEG) has been limited by a lack of a standardized classification system and interpretation terminology. In 2013, the American Clinical Neurophysiology Society (ACNS) published a guideline for standardized terminology and categorization in the description of continuous EEG in neonates. We sought to assess interrater agreement for this neonatal EEG categorization system as applied by a group of pediatric neurophysiologists. A total of 60 neonatal EEG studies were collected from three institutions. All EEG segments were from term neonates with hypoxic-ischemic encephalopathy. Three pediatric neurophysiologists independently reviewed each record using the ACNS standardized scoring system. Unweighted kappa values were calculated for interrater agreement of categorical data across multiple observers. Interrater agreement was very good for identification of seizures (κ = 0.93, p < 0.001), with perfect agreement in 95% of records (57 of 60). Interrater agreement was moderate for classifying records as normal or having any abnormality (κ = 0.49, p < 0.001), with perfect agreement in 78% of records (47 of 60). Interrater agreement was good in classifying EEG backgrounds on a 5-category scale (normal, excessively discontinuous, burst suppression, status epilepticus, or electrocerebral inactivity) (κ = 0.70, p < 0.001), with perfect agreement in 72% of records (43 of 60). Other specific background features had lower agreement, including voltage (κ = 0.41, p < 0.001), variability (κ = 0.35, p < 0.001), symmetry (κ = 0.18, p = 0.01), presence of abnormal sharp waves (κ < 0.20, p < 0.05), and presence of brief rhythmic discharges (κ < 0.20, p < 0.05). We found good or very good interrater agreement applying the ACNS system for identification of seizures and classification of EEG background. Other specific EEG features showed limited interrater agreement. Of importance to both clinicians and researchers, our findings support using the ACNS system in identifying seizures and classifying backgrounds of neonatal EEG recordings, but also suggest limited reproducibility for certain other EEG features. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

Human Brain Activity Patterns beyond the Isoelectric Line of Extreme Deep Coma

PubMed Central

Kroeger, Daniel; Florea, Bogdan; Amzica, Florin

2013-01-01

The electroencephalogram (EEG) reflects brain electrical activity. A flat (isoelectric) EEG, which is usually recorded during very deep coma, is considered to be a turning point between a living brain and a deceased brain. Therefore the isoelectric EEG constitutes, together with evidence of irreversible structural brain damage, one of the criteria for the assessment of brain death. In this study we use EEG recordings for humans on the one hand, and on the other hand double simultaneous intracellular recordings in the cortex and hippocampus, combined with EEG, in cats. They serve to demonstrate that a novel brain phenomenon is observable in both humans and animals during coma that is deeper than the one reflected by the isoelectric EEG, and that this state is characterized by brain activity generated within the hippocampal formation. This new state was induced either by medication applied to postanoxic coma (in human) or by application of high doses of anesthesia (isoflurane in animals) leading to an EEG activity of quasi-rhythmic sharp waves which henceforth we propose to call ν-complexes (Nu-complexes). Using simultaneous intracellular recordings in vivo in the cortex and hippocampus (especially in the CA3 region) we demonstrate that ν-complexes arise in the hippocampus and are subsequently transmitted to the cortex. The genesis of a hippocampal ν-complex depends upon another hippocampal activity, known as ripple activity, which is not overtly detectable at the cortical level. Based on our observations, we propose a scenario of how self-oscillations in hippocampal neurons can lead to a whole brain phenomenon during coma. PMID:24058669

Catastrophe optics of sharp-edge diffraction.

PubMed

Borghi, Riccardo

2016-07-01

A classical problem of diffraction theory, namely plane wave diffraction by sharp-edge apertures, is here reformulated from the viewpoint of the fairly new subject of catastrophe optics. On using purely geometrical arguments, properly embedded into a wave optics context, uniform analytical estimates of the diffracted wavefield at points close to fold caustics are obtained, within paraxial approximation, in terms of the Airy function and its first derivative. Diffraction from parabolic apertures is proposed to test reliability and accuracy of our theoretical predictions.

Electrical activity of the cingulate cortex. II. Cholinergic modulation.

PubMed

Borst, J G; Leung, L W; MacFabe, D F

1987-03-24

The role of the cholinergic innervation in the modulation of cingulate electrical activity was studied by means of pharmacological manipulations and brain lesions. In the normal rat, an irregular slow activity (ISA) accompanied with EEG-spikes was recorded in the cingulate cortex during immobility as compared to walking. Atropine sulfate, but not atropine methyl nitrate, increased ISA and the frequency of cingulate EEG-spikes. Pilocarpine suppressed ISA and EEG-spikes during immobility, and induced a slow (4-7 Hz) theta rhythm. Unilateral or bilateral lesions of the substantia innominata and ventral globus pallidus area using kainic acid did not significantly change the cingulate EEG or its relation to behavior. Large electrolytic lesions of the medial septal nuclei and vertical limbs of the diagonal band generally decreased or abolished all theta activity in the cingulate cortex and the hippocampus. However, in 5 rats the cingulate theta rhythm increased while the hippocampal theta disappeared after a medial septal lesion. The large, postlesion cingulate theta, accompanied by sharp EEG-spikes during its negative phase, is an unequivocal demonstration of the existence of a theta rhythm in the cingulate cortex, independent of the hippocampal rhythm. Cholinergic afferents from the medial septum and diagonal band nuclei are inferred to be responsible for the behavioral suppression of cingulate EEG-spikes and ISA, and partially for the generation of a local cingulate theta rhythm. However, an atropine-resistant pathway and a theta-suppressing pathway, possibly coming from the medial septum or the hippocampus, may also be important in cingulate theta generation.

Dynamic timecourse of typical childhood absence seizures: EEG, behavior and fMRI

PubMed Central

Bai, X; Vestal, M; Berman, R; Negishi, M; Spann, M; Vega, C; Desalvo, M; Novotny, EJ; Constable, RT; Blumenfeld, H

2010-01-01

Absence seizures are 5–10 second episodes of impaired consciousness accompanied by 3–4Hz generalized spike-and-wave discharge on electroencephalography (EEG). The timecourse of functional magnetic resonance imaging (fMRI) changes in absence seizures in relation to EEG and behavior is not known. We acquired simultaneous EEG-fMRI in 88 typical childhood absence seizures from 9 pediatric patients. We investigated behavior concurrently using a continuous performance task (CPT) or simpler repetitive tapping task (RTT). EEG time-frequency analysis revealed abrupt onset and end of 3–4 Hz spike-wave discharges with a mean duration of 6.6 s. Behavioral analysis also showed rapid onset and end of deficits associated with electrographic seizure start and end. In contrast, we observed small early fMRI increases in the orbital/medial frontal and medial/lateral parietal cortex >5s before seizure onset, followed by profound fMRI decreases continuing >20s after seizure end. This timecourse differed markedly from the hemodynamic response function (HRF) model used in conventional fMRI analysis, consisting of large increases beginning after electrical event onset, followed by small fMRI decreases. Other regions, such as the lateral frontal cortex, showed more balanced fMRI increases followed by approximately equal decreases. The thalamus showed delayed increases after seizure onset followed by small decreases, most closely resembling the HRF model. These findings reveal a complex and long lasting sequence of fMRI changes in absence seizures, which are not detectible by conventional HRF modeling in many regions. These results may be important mechanistically for seizure initiation and termination and may also contribute to changes in EEG and behavior. PMID:20427649

Epileptic encephalopathy with continuous spike-waves during sleep: the need for transition from childhood to adulthood medical care appears to be related to etiology.

PubMed

de Saint-Martin, Anne; Rudolf, Gabrielle; Seegmuller, Caroline; Valenti-Hirsch, Maria Paola; Hirsch, Edouard

2014-08-01

Epileptic encephalopathy with continuous diffuse spike-waves during slow-wave sleep (ECSWS) presents clinically with infrequent nocturnal focal seizures, atypical absences related to secondary bilateral synchrony, negative myoclonia, and atonic and rare generalized tonic-clonic seizures. The unique electroencephalography (EEG) pattern found in ECSWS consists of continuous, diffuse, bilateral spike-waves during slow-wave sleep. Despite the eventual disappearance of clinical seizures and EEG abnormalities by adolescence, the prognosis is guarded in most cases because of neuropsychological and behavioral deficits. ECSWS has a heterogeneous etiology (genetic, structural, and unknown). Because epilepsy and electroencephalography (EEG) abnormalities in epileptic encephalopathy with continuous diffuse spike-waves during slow-wave sleep (ECSWS) are self-limited and age related, the need for ongoing medical care and transition to adult care might be questioned. For adolescents in whom etiology remains unknown (possibly genetic) and who experience the disappearance of seizures and EEG abnormalities, there is rarely need for long-term neurologic follow-up, because often a relatively normal cognitive and social evolution follows. However, the majority of patients with structural and possibly "genetic syndromic" etiologies will have persistent cognitive deficits and will need suitable socioeducative care. Therefore, the transition process in ECSWS will depend mainly on etiology and its related features (epileptic active phase duration, and cognitive and behavioral evolution) and revolve around neuropsychological and social support rather than medical and pharmacologic follow-up. Wiley Periodicals, Inc. © 2014 International League Against Epilepsy.

Mu Wave Suppression during the Perception of Meaningless Syllables: EEG Evidence of Motor Recruitment

ERIC Educational Resources Information Center

Crawcour, Stephen; Bowers, Andrew; Harkrider, Ashley; Saltuklaroglu, Tim

2009-01-01

Motor involvement in speech perception has been recently studied using a variety of techniques. In the current study, EEG measurements from Cz, C3 and C4 electrodes were used to examine the relative power of the mu rhythm (i.e., 8-13 Hz) in response to various audio-visual speech and non-speech stimuli, as suppression of these rhythms is…

Heart rate calculation from ensemble brain wave using wavelet and Teager-Kaiser energy operator.

PubMed

Srinivasan, Jayaraman; Adithya, V

2015-01-01

Electroencephalogram (EEG) signal artifacts are caused by various factors, such as, Electro-oculogram (EOG), Electromyogram (EMG), Electrocardiogram (ECG), movement artifact and line interference. The relatively high electrical energy cardiac activity causes EEG artifacts. In EEG signal processing the general approach is to remove the ECG signal. In this paper, we introduce an automated method to extract the ECG signal from EEG using wavelet and Teager-Kaiser energy operator for R-peak enhancement and detection. From the detected R-peaks the heart rate (HR) is calculated for clinical diagnosis. To check the efficiency of our method, we compare the HR calculated from ECG signal recorded in synchronous with EEG. The proposed method yields a mean error of 1.4% for the heart rate and 1.7% for mean R-R interval. The result illustrates that, proposed method can be used for ECG extraction from single channel EEG and used in clinical diagnosis like estimation for stress analysis, fatigue, and sleep stages classification studies as a multi-model system. In addition, this method eliminates the dependence of additional synchronous ECG in extraction of ECG from EEG signal process.

Wave disc engine apparatus

DOEpatents

Muller, Norbert; Piechna, Janusz; Sun, Guangwei; Parraga, Pablo-Francisco

2018-01-02

A wave disc engine apparatus is provided. A further aspect employs a constricted nozzle in a wave rotor channel. A further aspect provides a sharp bend between an inlet and an outlet in a fluid pathway of a wave rotor, with the bend being spaced away from a peripheral edge of the wave rotor. A radial wave rotor for generating electricity in an automotive vehicle is disclosed in yet another aspect.

Effect of bright light on EEG activities and subjective sleepiness to mental task during nocturnal sleep deprivation.

PubMed

Yokoi, Mari; Aoki, Ken; Shimomura, Yoshihiro; Iwanaga, Koichi; Katsuura, Tetsuo; Shiomura, Yoshihiro

2003-11-01

The purpose of this study was to investigate the effect of the exposure to bright light on EEG activity and subjective sleepiness at rest and at the mental task during nocturnal sleep deprivation. Eight male subjects lay awake in semi-supine in a reclining seat from 21:00 to 04:30 under the bright (BL; >2500 lux) or the dim (DL; <150 lux) light conditions. During the sleep deprivation, the mental task (Stroop color-word conflict test: CWT) was performed each 15 min in one hour. EEG, subjective sleepiness, rectal and mean skin temperatures and urinary melatonin concentrations were measured. The subjective sleepiness increased with time of sleep deprivation during both rest and CWT under the DL condition. The exposure to bright light delayed for 2 hours the increase in subjective sleepiness at rest and suppressed the increase in that during CWT. The bright light exposure also delayed the increase in the theta and alpha wave activities in EEG at rest. In contrast, the effect of the bright light exposure on the theta and alpha wave activities disappeared by CWT. Additionally, under the BL condition, the entire theta activity during CWT throughout nocturnal sleep deprivation increased significantly from that in a rest condition. Our results suggest that the exposure to bright light throughout nocturnal sleep deprivation influences the subjective sleepiness during the mental task and the EEG activity, as well as the subjective sleepiness at rest. However, the effect of the bright light exposure on the EEG activity at the mental task diminishes throughout nocturnal sleep deprivation.

Non-convulsive seizures and electroencephalography findings as predictors of clinical outcomes at a tertiary intensive care unit in Saudi Arabia.

PubMed

Al-Said, Youssef A; Baeesa, Saleh S; Shivji, Zaitoon; Kayyali, Husam; Alqadi, Khalid; Kadi, Ghada; Cupler, Edward J; Abuzinadah, Ahmad R

2018-06-05

Electroencephalography (EEG) in the intensive care unit (ICU) is often done to detect non-convulsive seizures (NCS). The outcome of ICU patients with NCS strongly depends on the underlying etiology. The implication of NCS and other EEG findings on clinical outcome independent from their etiology is not well understood and our aim to investigate it. We retrospectively identified all adult patients in the ICU who underwent EEG monitoring between January 2008 and December 2011. The main goals were to define the rate of NCS or non-convulsive status epilepticus (NCSE) occurrence in our center among patients who underwent EEG monitoring and to examine if NCS/NCSE are associated with poor outcome [defined as death or dependence] with and without adjustment for underlying etiology. The rate of poor outcome among different EEG categories were also investigated. During the study period, 177 patients underwent EEG monitoring in our ICU. The overall outcome was poor in 62.7% of those undergoing EEG. The rate of occurrence of NCS/NCSE was 8.5% and was associated with poor outcome in 86.7% with an odds ratio (OR) of 5.1 (95% confidence interval [CI] 1.09-23.8). This association was maintained after adjusting for underlying etiologies with OR 5.6 (95% CI 1.05-29.6). The rate of poor outcome was high in the presence of periodic discharges and sharp and slow waves of 75% and 61.5%, respectively. Our cohort of ICU patients undergoing EEGs had a poor outcome. Those who developed NCS/NCSE experienced an even worse outcome regardless of the underlying etiology. Copyright © 2018 Elsevier B.V. All rights reserved.

3D near-surface soil response from H/V ambient-noise ratios

USGS Publications Warehouse

Wollery, E.W.; Street, R.

2002-01-01

The applicability of the horizontal-to-vertical (H/V) ambient-noise spectral ratio for characterizing earthquake site effects caused by nearsurface topography and velocity structures was evaluated at sites underlain by thick (i.e. >100 m) sediment deposits near the southern-end of the New Madrid seismic zone in the central United States. Three-component ambient-noise and velocity models derived from seismic (shearwave) refraction/reflection surveys showed that a relatively horizontal, sharp shear-wave velocity interface in the soil column resulted in an H/V spectral ratio with a single well-defined peak. Observations at sites with more than one sharp shear-wave velocity contrast and horizontally arranged soil layers resulted in at least two well-defined H/V spectral ratio peaks. Furthermore, at sites where there were sharp shear-wave velocity contrasts in nonhorizontal, near-surface soil layers, the H/V spectra exhibited a broad-bandwidth, relatively low amplitude signal instead of a single well-defined peak. ?? 2002 Elsevier Science Ltd. All rights reserved.

Proepileptic patterns in EEG of WAG/Rij rats

NASA Astrophysics Data System (ADS)

Grubov, Vadim V.; Sitnikova, Evgenia Yu.; Nedaivozov, Vladimir O.; Koronovskii, Alexey A.

2018-04-01

In this paper we study specific oscillatory patterns on EEG signals of WAG/Rij rats. These patterns are known as proepileptic because they occur in time period during the development of absence-epilepsy before fully-formed epileptic seizures. In the paper we analyze EEG signals of WAG/Rij rats with continuous wavelet transform and empirical mode decomposition in order to find particular features of epileptic spike-wave discharges and nonepileptic sleep spindles. Then we introduce proepileptic activity as patterns that combine features of epileptic and non-epileptic activity. We analyze proepileptic activity in order to specify its features and time-frequency structure.

Electroencephalographic and electromyographic changes during the use of detomidine and detomidine-butorphanol combination in standing horses.

PubMed

Kruluc, P; Nemec, Alenka

2006-03-01

Clinically, the use of detomidine and butorphanol is suitable for sedation and deepening of analgosedation. The aim of our study was to establish the influence of detomidine used alone and a butorphanol-detomidine combination on brain activity and to evaluate and compare brain responses (using electroencephalography, EEG) by recording SEF90 (spectral edge frequency 90%), individual brain wave fractions (beta, alpha, theta and delta) and electromyographic (EMG) changes in the left temporal muscle in standing horses. Ten clinically healthy cold-blooded horses were divided into two groups of five animals each. Group I received detomidine and Group II received detomidine followed by butorphanol 10 min later. SEF90, individual brain wave fractions and EMG were recorded with a pEEG (processed EEG) monitor using computerised processed electroencephalography and electromyography. The present study found that detomidine alone and the detomidine-butorphanol combination significantly reduced SEF90 and EMG, and they caused changes in individual brain wave fractions during sedation and particularly during analgosedation. The EMG results showed that the detomidine-butorphanol combination provided greater and longer muscle relaxation. Our EEG and EMG results confirmed that the detomidine-butorphanol combination is safer and more appropriate for painless and non-painless procedures on standing horses compared to detomidine alone.

Long-Range Correlation in alpha-Wave Predominant EEG in Human

NASA Astrophysics Data System (ADS)

Sharif, Asif; Chyan Lin, Der; Kwan, Hon; Borette, D. S.

2004-03-01

The background noise in the alpha-predominant EEG taken from eyes-open and eyes-closed neurophysiological states is studied. Scale-free characteristic is found in both cases using the wavelet approach developed by Simonsen and Nes [1]. The numerical results further show the scaling exponent during eyes-closed is consistently lower than eyes-open. We conjecture the origin of this difference is related to the temporal reconfiguration of the neural network in the brain. To further investigate the scaling structure of the EEG background noise, we extended the second order statistics to higher order moments using the EEG increment process. We found that the background fluctuation in the alpha-predominant EEG is predominantly monofractal. Preliminary results are given to support this finding and its implication in brain functioning is discussed. [1] A.H. Simonsen and O.M. Nes, Physical Review E, 58, 2779¡V2748 (1998).

Urodynamic function during sleep-like brain states in urethane anesthetized rats.

PubMed

Crook, J; Lovick, T

2016-01-28

The aim was to investigate urodynamic parameters and functional excitability of the periaqueductal gray matter (PAG) during changes in sleep-like brain states in urethane anesthetized rats. Simultaneous recordings of detrusor pressure, external urethral sphincter (EUS) electromyogram (EMG), cortical electroencephalogram (EEG), and single-unit activity in the PAG were made during repeated voiding induced by continuous infusion of saline into the bladder. The EEG cycled between synchronized, high-amplitude slow wave activity (SWA) and desynchronized low-amplitude fast activity similar to slow wave and 'activated' sleep-like brain states. During (SWA, 0.5-1.5 Hz synchronized oscillation of the EEG waveform) voiding became more irregular than in the 'activated' brain state (2-5 Hz low-amplitude desynchronized EEG waveform) and detrusor void pressure threshold, void volume threshold and the duration of bursting activity in the external urethral sphincter EMG were raised. The spontaneous firing rate of 23/52 neurons recorded within the caudal PAG and adjacent tegmentum was linked to the EEG state, with the majority of responsive cells (92%) firing more slowly during SWA. Almost a quarter of the cells recorded (12/52) showed phasic changes in firing rate that were linked to the occurrence of voids. Inhibition (n=6), excitation (n=4) or excitation/inhibition (n=2) was seen. The spontaneous firing rate of 83% of the micturition-responsive cells was sensitive to changes in EEG state. In nine of the 12 responsive cells (75%) the responses were reduced during SWA. We propose that during different sleep-like brain states changes in urodynamic properties occur which may be linked to changing excitability of the micturition circuitry in the periaqueductal gray. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Sharp wave/ripple network oscillations and learning-associated hippocampal maps.

PubMed

Csicsvari, Jozsef; Dupret, David

2014-02-05

Sharp wave/ripple (SWR, 150-250 Hz) hippocampal events have long been postulated to be involved in memory consolidation. However, more recent work has investigated SWRs that occur during active waking behaviour: findings that suggest that SWRs may also play a role in cell assembly strengthening or spatial working memory. Do such theories of SWR function apply to animal learning? This review discusses how general theories linking SWRs to memory-related function may explain circuit mechanisms related to rodent spatial learning and to the associated stabilization of new cognitive maps.

Rhythmic artifact of physiotherapy in intensive care unit EEG recordings.

PubMed

Young, Bryan; Raihan, Syed; Ladak, H; Kelly, Martin

2007-06-01

Intensive care unit EEG recordings are often contaminated by artifacts that are unseen elsewhere and are usually not documented. One is the rhythmic artifact of physiotherapy (RAP), which can follow the frequency of chest percussion or vibration with either fundamental or harmonic sinusoidal wave forms, affecting single or multiple channels. The occipital electrodes are the most commonly affected, but others can be involved separately or in combination. RAP can easily be mistaken for cerebrally originating rhythms, including seizures. RAP is most easily detected by examining the ECG channel, which usually captures the artifact, but video EEG provides another means, at least for chest percussion.

Alpha brain-wave neurofeedback training reduces psychopathology in a cohort of male and female Canadian aboriginals.

PubMed

Hardt, James V

2012-01-01

The study was conducted to determine if alpha brain-wave neurofeedback training can have positive psychological results by reducing anxiety and other psychopathology. The cohort participated in alpha brain-wave neurofeedback training for 76 minutes (day 1) to 120 or more minutes (days 5-7) daily for 7 days. Electroencephalogram (EEG) electrodes were attached to the head with conductive gel according to the 10-20 International Electrode Placement System. During training, participants were seated in a comfortable armchair within a soundproof and lightproof room. Brain-wave signals were amplified for processing by analog-to-digital converters and polygraphs, then filtered to the pure delta, theta, alpha, beta, and gamma bands as well as subbands of these bands of the EEG. For 2-minute epochs, trainees sat with their eyes closed in the dark listening to their feedback tones as the filtered alpha brain-wave EEG signals controlled the loudness of the tones. Then a "ding" sounded and the tones stopped. For 8 seconds, a monitor lit up with dimly illuminated, static numbers, indicating the strength of their alpha brain waves, after which the feedback tones resumed and the process was repeated. 40 adult volunteers were recruited from the aboriginal population (First Nations, Métis, and Inuit) of Canada. The cohort ranged in age from 25 to 60 years and included males and females. The study was conducted at Biocybernaut Institute of Canada in Victoria, British Columbia. Data was obtained to determine the effectiveness of this training by giving four psychological tests (Minnesota Multi-Phasic Personality Inventory, and the trait forms of the Multiple Affect Adjective Check List, Clyde Mood Scale, and Profile of Mood States) on the first day prior to commencing training and on the seventh day upon completion of the training. EEG data was also compiled throughout the training and analyzed as a factor of the training process. Postintervention data showed positive results with reduction of psychopathology when compared to the data from testing prior to the training. Analysis of this data showed improvement in several areas of psychopathology. Alpha brain-wave neurofeedback training daily for 7 days does have positive psychological results in adult male and female Canadian aboriginals as measured by data from four psychological tests on the participants.

Frequent sleep-related bitemporal focal seizures in transient epileptic amnesia syndrome: Evidence from ictal video-EEG.

PubMed

Burkholder, David B; Jones, Amy L; Jones, David T; Fabris, Rachel R; Britton, Jeffrey W; Lagerlund, Terrence D; So, Elson L; Cascino, Gregory D; Worrell, Gregory A; Shin, Cheolsu; St Louis, Erik K

2017-06-01

Two patients who shared similar presenting clinical features of anterograde and retrograde autobiographical amnesia typical of transient epileptic amnesia (TEA) underwent prolonged video electroencephalogram (VEEG) monitoring and were found to have sleep-activated epileptiform activity and frequent subclinical bitemporal seizures predominantly during sleep. Case 1 is a 59-year-old woman whose presenting complaint was memory impairment. Over 18 months, she had three distinct 8-h-long episodes of confusion and disorientation with persistent anterograde and retrograde autobiographical amnesia. VEEG recorded frequent interictal bitemporal sharp waves confined to sleep, and 14 subclinical seizures, also mostly during sleep. Case 2 is a 50-year-old woman with known focal epilepsy also presented with memory complaints. Over the course of 1 year, she had two discrete 2-h-long episodes of amnesia, with ongoing anterograde and retrograde autobiographical amnesia. VEEG recorded independent bitemporal sharp waves, and 14 subclinical seizures during sleep and drowsiness. Memory impairment improved in both patients with successful treatment of their seizures. Although the etiology of accelerated long-term forgetting (ALF) and remote memory impairment (RMI) in transient epileptic amnesia (TEA) is unknown, these cases suggest frequent sleep-related seizures may contribute, and they highlight the importance of video-EEG monitoring.

A Unified Dynamic Model for Learning, Replay, and Sharp-Wave/Ripples.

PubMed

Jahnke, Sven; Timme, Marc; Memmesheimer, Raoul-Martin

2015-12-09

Hippocampal activity is fundamental for episodic memory formation and consolidation. During phases of rest and sleep, it exhibits sharp-wave/ripple (SPW/R) complexes, which are short episodes of increased activity with superimposed high-frequency oscillations. Simultaneously, spike sequences reflecting previous behavior, such as traversed trajectories in space, are replayed. Whereas these phenomena are thought to be crucial for the formation and consolidation of episodic memory, their neurophysiological mechanisms are not well understood. Here we present a unified model showing how experience may be stored and thereafter replayed in association with SPW/Rs. We propose that replay and SPW/Rs are tightly interconnected as they mutually generate and support each other. The underlying mechanism is based on the nonlinear dendritic computation attributable to dendritic sodium spikes that have been prominently found in the hippocampal regions CA1 and CA3, where SPW/Rs and replay are also generated. Besides assigning SPW/Rs a crucial role for replay and thus memory processing, the proposed mechanism also explains their characteristic features, such as the oscillation frequency and the overall wave form. The results shed a new light on the dynamical aspects of hippocampal circuit learning. During phases of rest and sleep, the hippocampus, the "memory center" of the brain, generates intermittent patterns of strongly increased overall activity with high-frequency oscillations, the so-called sharp-wave/ripples. We investigate their role in learning and memory processing. They occur together with replay of activity sequences reflecting previous behavior. Developing a unifying computational model, we propose that both phenomena are tightly linked, by mutually generating and supporting each other. The underlying mechanism depends on nonlinear amplification of synchronous inputs that has been prominently found in the hippocampus. Besides assigning sharp-wave/ripples a crucial role for replay generation and thus memory processing, the proposed mechanism also explains their characteristic features, such as the oscillation frequency and the overall wave form. Copyright © 2015 the authors 0270-6474/15/3516236-23$15.00/0.

Analysis of bioelectric records and fabrication of phototype sleep analysis equipment

NASA Technical Reports Server (NTRS)

Kellaway, P.

1972-01-01

A computer-analysis technique was used to evaluate the changes in the waking EEGs of 5 normal subjects which occurred during the oral administration of flurazepam hydrochloride (Dalmane). While the subjects were receiving the drug, there was an increase in the amount of beta (14-38 c/sec) activity in fronto-central EEG leads in all 5 subjects. This increase in beta activity was characterized by a highly consistent increase in the number of waves that occurred during an EEG recording interval of fixed duration and by a less consistent increase in average wave amplitude. There was no detectable change in mean EEG wavelength (frequency) within the beta frequency range. The EEG patterns reverted to their baseline condition during 2-3 weeks after withdrawal of the drug. Analysis of the alpha, theta and delta components of the EEG indicated no changes during or following administration of the drug. This study clearly illustrates the usefulness of specific computer-analysis techniques in the characterization and quantification of sleep-promoting drugs upon the EEG of the normal young adults in the waking state. Two preamplifiers and 150 EEG monitoring caps with electrodes were delivered to MSC.

CDKL5 gene-related epileptic encephalopathy: electroclinical findings in the first year of life.

PubMed

Melani, Federico; Mei, Davide; Pisano, Tiziana; Savasta, Salvatore; Franzoni, Emilio; Ferrari, Anna Rita; Marini, Carla; Guerrini, Renzo

2011-04-01

Cyclin-dependent kinase-like 5 (CDKL5) gene abnormalities cause an early-onset epileptic encephalopathy. We performed video-electroencephalography (video-EEG) monitoring early in the course of CDKL5-related epileptic encephalopathy in order to examine the early electroclinical characteristics of the condition. We used video-EEG to monitor six infants (five females, one male) with CDKL5-related epileptic encephalopathy (five mutations; one deletion), at ages 45 days to 12 months and followed them up to the ages of 14 months to 5 years (mean age 23 mo). We focused our analysis on the first year of life. The results were evaluated against those of a comparison group of nine infants (aged below 1y) with epileptic encephalography who had tested negative for CDKL5 mutations and deletions. One infant exhibited normal background activity, three exhibited moderate slowing, and two exhibited a suppression burst pattern. Two participants had epileptic spasms and four had a stereotyped complex seizure pattern, which we defined as a 'prolonged' generalized tonic-clonic event consisting of a tonic-tonic/vibratory contraction, followed by a clonic phase with series of spasms, gradually translating into repetitive distal myoclonic jerks. Seizure duration ranged from 2 to 4 minutes. The EEG correlate of each clinical phase included an initial electrodecremental event (tonic vibratory phase), irregular series of sharp waves and spike slow waves (clonic phase with series of spasms), and bilateral rhythmic sharp waves (time locked with myoclonus). Infants with CDKL5-related early epileptic encephalopathy can present in the first year of life with an unusual electroclinical pattern of 'prolonged' generalized tonic-clonic seizures. © The Authors. Journal compilation © Mac Keith Press 2011.

High Resolution Topography of Age-Related Changes in Non-Rapid Eye Movement Sleep Electroencephalography

PubMed Central

Sprecher, Kate E.; Riedner, Brady A.; Smith, Richard F.; Tononi, Giulio; Davidson, Richard J.; Benca, Ruth M.

2016-01-01

Sleeping brain activity reflects brain anatomy and physiology. The aim of this study was to use high density (256 channel) electroencephalography (EEG) during sleep to characterize topographic changes in sleep EEG power across normal aging, with high spatial resolution. Sleep was evaluated in 92 healthy adults aged 18–65 years old using full polysomnography and high density EEG. After artifact removal, spectral power density was calculated for standard frequency bands for all channels, averaged across the NREM periods of the first 3 sleep cycles. To quantify topographic changes with age, maps were generated of the Pearson’s coefficient of the correlation between power and age at each electrode. Significant correlations were determined by statistical non-parametric mapping. Absolute slow wave power declined significantly with increasing age across the entire scalp, whereas declines in theta and sigma power were significant only in frontal regions. Power in fast spindle frequencies declined significantly with increasing age frontally, whereas absolute power of slow spindle frequencies showed no significant change with age. When EEG power was normalized across the scalp, a left centro-parietal region showed significantly less age-related decline in power than the rest of the scalp. This partial preservation was particularly significant in the slow wave and sigma bands. The effect of age on sleep EEG varies substantially by region and frequency band. This non-uniformity should inform the design of future investigations of aging and sleep. This study provides normative data on the effect of age on sleep EEG topography, and provides a basis from which to explore the mechanisms of normal aging as well as neurodegenerative disorders for which age is a risk factor. PMID:26901503

Slow oscillations orchestrating fast oscillations and memory consolidation.

PubMed

Mölle, Matthias; Born, Jan

2011-01-01

Slow-wave sleep (SWS) facilitates the consolidation of hippocampus-dependent declarative memory. Based on the standard two-stage memory model, we propose that memory consolidation during SWS represents a process of system consolidation which is orchestrated by the neocortical <1Hz electroencephalogram (EEG) slow oscillation and involves the reactivation of newly encoded representations and their subsequent redistribution from temporary hippocampal to neocortical long-term storage sites. Indeed, experimental induction of slow oscillations during non-rapid eye movement (non-REM) sleep by slowly alternating transcranial current stimulation distinctly improves consolidation of declarative memory. The slow oscillations temporally group neuronal activity into up-states of strongly enhanced neuronal activity and down-states of neuronal silence. In a feed-forward efferent action, this grouping is induced not only in the neocortex but also in other structures relevant to consolidation, namely the thalamus generating 10-15Hz spindles, and the hippocampus generating sharp wave-ripples, with the latter well known to accompany a replay of newly encoded memories taking place in hippocampal circuitries. The feed-forward synchronizing effect of the slow oscillation enables the formation of spindle-ripple events where ripples and accompanying reactivated hippocampal memory information become nested into the single troughs of spindles. Spindle-ripple events thus enable reactivated memory-related hippocampal information to be fed back to neocortical networks in the excitable slow oscillation up-state where they can induce enduring plastic synaptic changes underlying the effective formation of long-term memories. Copyright © 2011 Elsevier B.V. All rights reserved.

[Time-organization of EEG patterns' structure in anxiety and phobic disorders].

PubMed

Sviatogor, I A; Mokhovikova, I A

2005-01-01

Thirty-five patients, aged 19-48 years (mean age 38 years) with anxiety and phobic disorders were examined. According to ICD-10 criteria--social phobia (F40.1), panic disorder (F41.0), somatoform autonomic dysfunction (F45.3) were diagnosed. Using electroencephalography data, qualitative and quantitative characteristics of the time- and spatial-organization of brain EEG activity in anxiety and phobic disorders of different severity were established. It were determined 4 types of wave interactions between EEG components, which reflected a different extent of the regulatory mechanisms lesions: 2 structures with one core component (alpha or beta), a structure with two core components and a non-organized structure.

Going local: insights from EEG and stereo-EEG studies of the human sleep-wake cycle.

PubMed

Ferrara, Michele; De Gennaro, Luigi

2011-01-01

In the present paper, we reviewed a large body of evidence, mainly from quantitative EEG studies of our laboratory, supporting the notion that sleep is a local and use-dependent process. Quantitative analyses of sleep EEG recorded from multiple cortical derivations clearly indicate that every sleep phenomenon, from sleep onset to the awakening, is strictly local in nature. Sleep onset first occurs in frontal areas, and a frontal predominance of low-frequency power persists in the first part of the night, when the homeostatic processes mainly occur, and then it vanishes. Upon awakening, we showed an asynchronous EEG activation of different cortical areas, the more anterior ones being the first to wake up. During extended periods of wakefulness, the increase of sleepiness-related low-EEG frequencies is again evident over the frontal derivations. Similarly, experimental manipulations of sleep length by total sleep deprivation, partial sleep curtailment or even selective slow-wave sleep deprivation lead to a slow-wave activity rebound localized especially on the anterior derivations. Thus, frontal areas are crucially involved in sleep homeostasis. According to the local use-dependent theory, this would derive from a higher sleep need of the frontal cortex, which in turn is due to its higher levels of activity during wakefulness. The fact that different brain regions can simultaneously exhibit different sleep intensities indicates that sleep is not a spatially global and uniform state, as hypothesized in the theory. We have also reviewed recent evidence of localized effects of learning and plasticity on EEG sleep measures. These studies provide crucial support to a key concept in the theory, the one claiming that local sleep characteristics should be use-dependent. Finally, we have reported data corroborating the notion that sleep is not necessarily present simultaneously in the entire brain. Our stereo-EEG recordings clearly indicate that sleep and wakefulness can co-exist in different areas, suggesting that vigilance states are not necessarily temporally discrete states. We conclude that understanding local variations in sleep propensity and depth, especially as a result of brain plasticity, may provide in the near future insightful hints into the fundamental functions of sleep.

Formation of large-scale structures with sharp density gradient through Rayleigh-Taylor growth in a two-dimensional slab under the two-fluid and finite Larmor radius effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goto, R.; Hatori, T.; Miura, H., E-mail: miura.hideaki@nifs.ac.jp

Two-fluid and the finite Larmor effects on linear and nonlinear growth of the Rayleigh-Taylor instability in a two-dimensional slab are studied numerically with special attention to high-wave-number dynamics and nonlinear structure formation at a low β-value. The two effects stabilize the unstable high wave number modes for a certain range of the β-value. In nonlinear simulations, the absence of the high wave number modes in the linear stage leads to the formation of the density field structure much larger than that in the single-fluid magnetohydrodynamic simulation, together with a sharp density gradient as well as a large velocity difference. Themore » formation of the sharp velocity difference leads to a subsequent Kelvin-Helmholtz-type instability only when both the two-fluid and finite Larmor radius terms are incorporated, whereas it is not observed otherwise. It is shown that the emergence of the secondary instability can modify the outline of the turbulent structures associated with the primary Rayleigh-Taylor instability.« less

Myoclonic Jerks and Schizophreniform Syndrome: Case Report and Literature Review.

PubMed

Endres, Dominique; Altenmüller, Dirk-M; Feige, Bernd; Maier, Simon J; Nickel, Kathrin; Hellwig, Sabine; Rausch, Jördis; Ziegler, Christiane; Domschke, Katharina; Doerr, John P; Egger, Karl; Tebartz van Elst, Ludger

2018-01-01

Background: Schizophreniform syndromes can be divided into primary idiopathic forms as well as different secondary organic subgroups (e.g., paraepileptic, epileptic, immunological, or degenerative). Secondary epileptic explanatory approaches have often been discussed in the past, due to the high rates of electroencephalography (EEG) alterations in patients with schizophrenia. In particular, temporal lobe epilepsy is known to be associated with schizophreniform symptoms in well-described constellations. In the literature, juvenile myoclonic epilepsy has been linked to emotionally unstable personality traits, depression, anxiety, and executive dysfunction; however, the association with schizophrenia is largely unclear. Case presentation: We present the case of a 28-year-old male student suffering from mild myoclonic jerks, mainly of the upper limbs, as well as a predominant paranoid-hallucinatory syndrome with attention deficits, problems with working memory, depressive-flat mood, reduced energy, fast stimulus satiation, delusional and audible thoughts, tactile hallucinations, thought inspirations, and severe sleep disturbances. Cerebral magnetic resonance imaging and cerebrospinal fluid analyses revealed no relevant abnormalities. The routine EEG and the first EEG after sleep deprivation (under treatment with oxazepam) also returned normal findings. Video telemetry over one night, which included a partial sleep-deprivation EEG, displayed short generalized spike-wave complexes and polyspikes, associated with myoclonic jerks, after waking in the morning. Video-EEG monitoring over 5 days showed over 100 myoclonic jerks of the upper limbs, frequently with generalized spike-wave complexes with left or right accentuation. Therefore, we diagnosed juvenile myoclonic epilepsy. Discussion: This case report illustrates the importance of extended EEG diagnostics in patients with schizophreniform syndromes and myoclonic jerks. The schizophreniform symptoms in the framework of epileptiform EEG activity can be interpreted as a (para)epileptic mechanism due to local area network inhibition (LANI). Following the LANI hypothesis, paranoid hallucinatory symptoms are not due to primary excitatory activity (as myoclonic jerks are) but rather to the secondary process of hyperinhibition triggered by epileptic activity. Identifying subgroups of schizophreniform patients with comorbid epilepsy is important because of the potential benefits of optimized pharmacological treatment.

Spatio-temporal specialization of GABAergic septo-hippocampal neurons for rhythmic network activity.

PubMed

Unal, Gunes; Crump, Michael G; Viney, Tim J; Éltes, Tímea; Katona, Linda; Klausberger, Thomas; Somogyi, Peter

2018-03-03

Medial septal GABAergic neurons of the basal forebrain innervate the hippocampus and related cortical areas, contributing to the coordination of network activity, such as theta oscillations and sharp wave-ripple events, via a preferential innervation of GABAergic interneurons. Individual medial septal neurons display diverse activity patterns, which may be related to their termination in different cortical areas and/or to the different types of innervated interneurons. To test these hypotheses, we extracellularly recorded and juxtacellularly labeled single medial septal neurons in anesthetized rats in vivo during hippocampal theta and ripple oscillations, traced their axons to distant cortical target areas, and analyzed their postsynaptic interneurons. Medial septal GABAergic neurons exhibiting different hippocampal theta phase preferences and/or sharp wave-ripple related activity terminated in restricted hippocampal regions, and selectively targeted a limited number of interneuron types, as established on the basis of molecular markers. We demonstrate the preferential innervation of bistratified cells in CA1 and of basket cells in CA3 by individual axons. One group of septal neurons was suppressed during sharp wave-ripples, maintained their firing rate across theta and non-theta network states and mainly fired along the descending phase of CA1 theta oscillations. In contrast, neurons that were active during sharp wave-ripples increased their firing significantly during "theta" compared to "non-theta" states, with most firing during the ascending phase of theta oscillations. These results demonstrate that specialized septal GABAergic neurons contribute to the coordination of network activity through parallel, target area- and cell type-selective projections to the hippocampus.

Frontal predominance of a relative increase in sleep delta and theta EEG activity after sleep loss in humans

NASA Technical Reports Server (NTRS)

Cajochen, C.; Foy, R.; Dijk, D. J.; Czeisler, C. A. (Principal Investigator)

1999-01-01

The effect of sleep deprivation (40 h) on topographic and temporal aspects of electroencephalographic (EEG) activity during sleep was investigated by all night spectral analysis in six young volunteers. The sleep-deprivation-induced increase of EEG power density in the delta and theta frequencies (1-7 Hz) during nonREM sleep, assessed along the antero-posterior axis (midline: Fz, Cz, Pz, Oz), was significantly larger in the more frontal derivations (Fz, Cz) than in the more parietal derivations (Pz, Oz). This frequency-specific frontal predominance was already present in the first 30 min of recovery sleep, and dissipated in the course of the 8-h sleep episode. The data demonstrate that the enhancement of slow wave EEG activity during sleep following extended wakefulness is most pronounced in frontal cortical areas.

Understanding the pathophysiology of reflex epilepsy using simultaneous EEG-fMRI.

PubMed

Sandhya, Manglore; Bharath, Rose Dawn; Panda, Rajanikant; Chandra, S R; Kumar, Naveen; George, Lija; Thamodharan, A; Gupta, Arun Kumar; Satishchandra, P

2014-03-01

Measuring neuro-haemodynamic correlates in the brain of epilepsy patients using EEG-fMRI has opened new avenues in clinical neuroscience, as these are two complementary methods for understanding brain function. In this study, we investigated three patients with drug-resistant reflex epilepsy using EEG-fMRI. Different types of reflex epilepsy such as eating, startle myoclonus, and hot water epilepsy were included in the study. The analysis of EEG-fMRI data was based on the visual identification of interictal epileptiform discharges on scalp EEG. The convolution of onset time and duration of these epilepsy spikes was estimated, and using these condition-specific effects in a general linear model approach, we evaluated activation of fMRI. Patients with startle myoclonus epilepsy experienced epilepsy in response to sudden sound or touch, in association with increased delta and theta activity with a spike-and-slow-wave pattern of interictal epileptiform discharges on EEG and fronto-parietal network activation pattern on SPECT and EEG-fMRI. Eating epilepsy was triggered by sight or smell of food and fronto-temporal discharges were noted on video-EEG (VEEG). Similarly, fronto-temporo-parietal involvement was noted on SPECT and EEG-fMRI. Hot water epilepsy was triggered by contact with hot water either in the bath or by hand immersion, and VEEG showed fronto-parietal involvement. SPECT and EEG fMRI revealed a similar fronto-parietal-occipital involvement. From these results, we conclude that continuous EEG recording can improve the modelling of BOLD changes related to interictal epileptic activity and this can thus be used to understand the neuro-haemodynamic substrates involved in reflex epilepsy.

Wireless brain-machine interface using EEG and EOG: brain wave classification and robot control

NASA Astrophysics Data System (ADS)

Oh, Sechang; Kumar, Prashanth S.; Kwon, Hyeokjun; Varadan, Vijay K.

2012-04-01

A brain-machine interface (BMI) links a user's brain activity directly to an external device. It enables a person to control devices using only thought. Hence, it has gained significant interest in the design of assistive devices and systems for people with disabilities. In addition, BMI has also been proposed to replace humans with robots in the performance of dangerous tasks like explosives handling/diffusing, hazardous materials handling, fire fighting etc. There are mainly two types of BMI based on the measurement method of brain activity; invasive and non-invasive. Invasive BMI can provide pristine signals but it is expensive and surgery may lead to undesirable side effects. Recent advances in non-invasive BMI have opened the possibility of generating robust control signals from noisy brain activity signals like EEG and EOG. A practical implementation of a non-invasive BMI such as robot control requires: acquisition of brain signals with a robust wearable unit, noise filtering and signal processing, identification and extraction of relevant brain wave features and finally, an algorithm to determine control signals based on the wave features. In this work, we developed a wireless brain-machine interface with a small platform and established a BMI that can be used to control the movement of a robot by using the extracted features of the EEG and EOG signals. The system records and classifies EEG as alpha, beta, delta, and theta waves. The classified brain waves are then used to define the level of attention. The acceleration and deceleration or stopping of the robot is controlled based on the attention level of the wearer. In addition, the left and right movements of eye ball control the direction of the robot.

Video Game Adapts To Brain Waves

NASA Technical Reports Server (NTRS)

Pope, Alan T.; Bogart, Edward H.

1994-01-01

Electronic training system based on video game developed to help children afflicted with attention-deficit disorder (ADD) learn to prolong their attention spans. Uses combination of electroencephalography (EEG) and adaptive control to encourage attentiveness. Monitors trainee's brain-wave activity: if EEG signal indicates attention is waning, system increases difficulty of game, forcing trainee to devote more attention to it. Game designed to make trainees want to win and, in so doing, learn to pay attention for longer times.

Recognizing of stereotypic patterns in epileptic EEG using empirical modes and wavelets

NASA Astrophysics Data System (ADS)

Grubov, V. V.; Sitnikova, E.; Pavlov, A. N.; Koronovskii, A. A.; Hramov, A. E.

2017-11-01

Epileptic activity in the form of spike-wave discharges (SWD) appears in the electroencephalogram (EEG) during absence seizures. This paper evaluates two approaches for detecting stereotypic rhythmic activities in EEG, i.e., the continuous wavelet transform (CWT) and the empirical mode decomposition (EMD). The CWT is a well-known method of time-frequency analysis of EEG, whereas EMD is a relatively novel approach for extracting signal's waveforms. A new method for pattern recognition based on combination of CWT and EMD is proposed. It was found that this combined approach resulted to the sensitivity of 86.5% and specificity of 92.9% for sleep spindles and 97.6% and 93.2% for SWD, correspondingly. Considering strong within- and between-subjects variability of sleep spindles, the obtained efficiency in their detection was high in comparison with other methods based on CWT. It is concluded that the combination of a wavelet-based approach and empirical modes increases the quality of automatic detection of stereotypic patterns in rat's EEG.

Effects of green and black tea consumption on brain wave activities in healthy volunteers as measured by a simplified Electroencephalogram (EEG): A feasibility study.

PubMed

Okello, Edward J; Abadi, Awatf M; Abadi, Saad A

2016-06-01

Tea has been associated with many mental benefits, such as attention enhancement, clarity of mind, and relaxation. These psychosomatic states can be measured in terms of brain activity using an electroencephalogram (EEG). Brain activity can be assessed either during a state of passive activity or when performing attention tasks and it can provide useful information about the brain's state. This study investigated the effects of green and black consumption on brain activity as measured by a simplified EEG, during passive activity. Eight healthy volunteers participated in the study. The EEG measurements were performed using a two channel EEG brain mapping instrument - HeadCoach™. Fast Fourier transform algorithm and EEGLAB toolbox using the Matlab software were used for data processing and analysis. Alpha, theta, and beta wave activities were all found to increase after 1 hour of green and black tea consumption, albeit, with very considerable inter-individual variations. Our findings provide further evidence for the putative beneficial effects of tea. The highly significant increase in theta waves (P < 0.004) between 30 minutes and 1 hour post-consumption of green tea may be an indication of its putative role in cognitive function, specifically alertness and attention. There were considerable inter-individual variations in response to the two teas which may be due genetic polymorphisms in metabolism and/or influence of variety/blend, dose and content of the selected products whose chemistry and therefore efficacy will have been influenced by 'from field to shelf practices'.

Acute effect of carbamazepine on corticothalamic 5-9-Hz and thalamocortical spindle (10-16-Hz) oscillations in the rat.

PubMed

Zheng, Thomas W; O'Brien, Terence J; Kulikova, Sofya P; Reid, Christopher A; Morris, Margaret J; Pinault, Didier

2014-03-01

A major side effect of carbamazepine (CBZ), a drug used to treat neurological and neuropsychiatric disorders, is drowsiness, a state characterized by increased slow-wave oscillations with the emergence of sleep spindles in the electroencephalogram (EEG). We conducted cortical EEG and thalamic cellular recordings in freely moving or lightly anesthetized rats to explore the impact of CBZ within the intact corticothalamic (CT)-thalamocortical (TC) network, more specifically on CT 5-9-Hz and TC spindle (10-16-Hz) oscillations. Two to three successive 5-9-Hz waves were followed by a spindle in the cortical EEG. A single systemic injection of CBZ (20 mg/kg) induced a significant increase in the power of EEG 5-9-Hz oscillations and spindles. Intracellular recordings of glutamatergic TC neurons revealed 5-9-Hz depolarizing wave-hyperpolarizing wave sequences prolonged by robust, rhythmic spindle-frequency hyperpolarizing waves. This hybrid sequence occurred during a slow hyperpolarizing trough, and was at least 10 times more frequent under the CBZ condition than under the control condition. The hyperpolarizing waves reversed at approximately -70 mV, and became depolarizing when recorded with KCl-filled intracellular micropipettes, indicating that they were GABAA receptor-mediated potentials. In neurons of the GABAergic thalamic reticular nucleus, the principal source of TC GABAergic inputs, CBZ augmented both the number and the duration of sequences of rhythmic spindle-frequency bursts of action potentials. This indicates that these GABAergic neurons are responsible for the generation of at least the spindle-frequency hyperpolarizing waves in TC neurons. In conclusion, CBZ potentiates GABAA receptor-mediated TC spindle oscillations. Furthermore, we propose that CT 5-9-Hz waves can trigger TC spindles. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Acute CT perfusion changes in seizure patients presenting to the emergency department with stroke-like symptoms: correlation with clinical and electroencephalography findings.

PubMed

Payabvash, S; Oswood, M C; Truwit, C L; McKinney, A M

2015-10-01

To determine acute computed tomography perfusion (CTP) changes in seizure patients presenting with stroke-like symptoms and to correlate those changes with clinical presentation and electroencephalography (EEG). The medical records of all patients who presented to the emergency department with acute stroke-like symptoms and underwent CTP (n=1085) over a 5.5-year period were reviewed. Patients were included who had primary seizure as the final diagnosis, and underwent CTP within 3 hours of symptom onset. A subset of patients had a follow-up EEG within 7 days. The perfusion changes and EEG findings were compared between different clinical presentations. Eighteen of 1085 patients (1.7%) who underwent CTP following an acute stroke-like presentation were included. The abnormality on CTP was usually focal, unilateral hyperperfusion - increased relative cerebral blood flow (rCBF) and volume (rCBV) (n=14/18), which most often affected the temporal lobe. Those patients who presented with a motor or speech deficit (n=12) had a higher temporal lobe rCBV, and rCBF, and lower relative mean transit time (rMTT) compared to those with non-focal neurological deficit at presentation. Early EEG was available in 13 patients; a sharp-spike epileptiform EEG discharge pattern (n=5) was associated with higher temporal lobe ipsilateral rCBF and rCBV, and lower rMTT on admission CTP examination. Seizure patients who present with a unilateral motor or speech deficit most commonly have contralateral hyperperfusion in the corresponding eloquent brain regions on the acute-stage CTP examination. In such patients, epileptiform discharges on the early follow-up EEG are associated with ipsilateral hyperperfusion on the admission CTP. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Head-on collision of normal shock waves with rigid porous materials

NASA Astrophysics Data System (ADS)

Levy, A.; Ben-Dor, G.; Skews, B. W.; Sorek, S.

1993-08-01

The head-on collision of a planar shock wave with a rigid porous material has been investigated experimentally in a 75 mm × 75 mm shock tube. The experimental study indicated that unlike the reflection from a flexible porous material (e.g., polyurethane foam) where the transmitted compression waves do not converge to a sharp shock wave, in the case of a rigid porous material (e.g., alumina) the transmitted compression waves do converge to a sharp shock wave, which decays as it propagates along the porous material. In addition to this major difference, many other differences were observed. They are outlined in the following sections. Based on these observations a suggestion modifying the phenomenology of the reflection/interaction process in the case a porous material with large permeability is proposed.

Characteristic changes in the physiological components of cybersickness.

PubMed

Kim, Young Youn; Kim, Hyun Ju; Kim, Eun Nam; Ko, Hee Dong; Kim, Hyun Taek

2005-09-01

We investigated the characteristic changes in the physiology of cybersickness when subjects were exposed to virtual reality. Sixty-one participants experienced a virtual navigation for a total of 9.5 min, and were required to detect specific virtual objects. Three questionnaires for sickness susceptibility and immersive tendency were obtained before the navigation. Sixteen electrophysiological signals were recorded before, during, and after the navigation. The severity of cybersickness experienced by participants was reported from a simulator sickness questionnaire after the navigation. The total severity of cybersickness had a significant positive correlation with gastric tachyarrhythmia, eyeblink rate, heart period, and EEG delta wave and a negative correlation with EEG beta wave. These results suggest that cybersickness accompanies the pattern changes in the activities of the central and the autonomic nervous systems.

Method and apparatus for extraction of low-frequency artifacts from brain waves for alertness detection

DOEpatents

Clapp, Ned E.; Hively, Lee M.

1997-01-01

Methods and apparatus automatically detect alertness in humans by monitoring and analyzing brain wave signals. Steps include: acquiring the brain wave (EEG or MEG) data from the subject, digitizing the data, separating artifact data from raw data, and comparing trends in f-data to alertness indicators, providing notification of inadequate alertness.

EEG Mu Rhythm and Imitation Impairments in Individuals with Autism Spectrum Disorder

PubMed Central

Bernier, R.; Dawson, G.; Webb, S.; Murias, M.

2009-01-01

Imitation ability has consistently been shown to be impaired in individuals with autism. A dysfunctional execution/observation matching system has been proposed to account for this impairment. The EEG mu rhythm is believed to reflect an underlying execution/observation matching system. This study investigated evidence of differential mu rhythm attenuation during the observation, execution, and imitation of movements and examined its relation to behaviorally assessed imitation abilities. Fourteen high-functioning adults with autism spectrum disorder (ASD) and 15 IQ- and age-matched typical adults participated. On the behavioral imitation task, adults with ASD demonstrated significantly poorer performance compared to typical adults in all domains of imitation ability. On the EEG task, both groups demonstrated significant attenuation of the mu rhythm when executing an action. However, when observing movement, the individuals with ASD showed significantly reduced attenuation of the mu wave. Behaviorally assessed imitation skills were correlated with degree of mu wave attenuation during observation of movement. These findings suggest that there is execution/observation matching system dysfunction in individuals with autism and that this matching system is related to degree of impairment in imitation abilities. PMID:17451856

Potential for unreliable interpretation of EEG recorded with microelectrodes.

PubMed

Stacey, William C; Kellis, Spencer; Greger, Bradley; Butson, Christopher R; Patel, Paras R; Assaf, Trevor; Mihaylova, Temenuzhka; Glynn, Simon

2013-08-01

Recent studies in epilepsy, cognition, and brain machine interfaces have shown the utility of recording intracranial electroencephalography (iEEG) with greater spatial resolution. Many of these studies utilize microelectrodes connected to specialized amplifiers that are optimized for such recordings. We recently measured the impedances of several commercial microelectrodes and demonstrated that they will distort iEEG signals if connected to clinical EEG amplifiers commonly used in most centers. In this study we demonstrate the clinical implications of this effect and identify some of the potential difficulties in using microelectrodes. Human iEEG data were digitally filtered to simulate the signal recorded by a hybrid grid (two macroelectrodes and eight microelectrodes) connected to a standard EEG amplifier. The filtered iEEG data were read by three trained epileptologists, and high frequency oscillations (HFOs) were detected with a well-known algorithm. The filtering method was verified experimentally by recording an injected EEG signal in a saline bath with the same physical acquisition system used to generate the model. Several electrodes underwent scanning electron microscopy (SEM). Macroelectrode recordings were unaltered compared to the source iEEG signal, but microelectrodes attenuated low frequencies. The attenuated signals were difficult to interpret: all three clinicians changed their clinical scoring of slowing and seizures when presented with the same data recorded on different sized electrodes. The HFO detection algorithm was oversensitive with microelectrodes, classifying many more HFOs than when the same data were recorded with macroelectrodes. In addition, during experimental recordings the microelectrodes produced much greater noise as well as large baseline fluctuations, creating sharply contoured transients, and superimposed "false" HFOs. SEM of these microelectrodes demonstrated marked variability in exposed electrode surface area, lead fractures, and sharp edges. Microelectrodes should not be used with low impedance (<1 GΩ) amplifiers due to severe signal attenuation and variability that changes clinical interpretations. The current method of preparing microelectrodes can leave sharp edges and nonuniform amounts of exposed wire. Even when recorded with higher impedance amplifiers, microelectrode data are highly prone to artifacts that are difficult to interpret. Great care must be taken when analyzing iEEG from high impedance microelectrodes. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.

Method and apparatus for extraction of low-frequency artifacts from brain waves for alertness detection

DOEpatents

Clapp, N.E.; Hively, L.M.

1997-05-06

Methods and apparatus automatically detect alertness in humans by monitoring and analyzing brain wave signals. Steps include: acquiring the brain wave (EEG or MEG) data from the subject, digitizing the data, separating artifact data from raw data, and comparing trends in f-data to alertness indicators, providing notification of inadequate alertness. 4 figs.

Landau-Kleffner Syndrome, Electrical Status Epilepticus in Slow Wave Sleep, and Language Regression in Children

ERIC Educational Resources Information Center

McVicar, Kathryn A.; Shinnar, Shlomo

2004-01-01

The Landau-Kleffner syndrome (LKS) and electrical status epilepticus in slow wave sleep (ESES) are rare childhood-onset epileptic encephalopathies in which loss of language skills occurs in the context of an epileptiform EEG activated in sleep. Although in LKS the loss of function is limited to language, in ESES there is a wider spectrum of…

[The noncoherent components of evoked brain activity].

PubMed

Kovalev, V P; Novototskiĭ-Vlasov, V Iu

1998-01-01

Poststimulus spectral EEG changes and their correlation with evoked potential (EP) were analyzed. The non-stationary components of the brain evoked activity were revealed in 32 volunteers during simple motor reaction and choice reaction to visual stimuli. This nonstationary activity was manifested in poststimulus changes in the mean wave half-period duration (MWHPD) and mean wave half-period power of the delta- and beta-frequency oscillations computed in the EEG realizations after the EP subtraction. The latencies of high-frequency EP components fell into the intervals of the MWHPD decrease and increase in the power of beta-oscillations, and the latencies of low-frequency EP components coincided with the intervals of the MWHPD increase and decrease in the power of delta and beta-oscillations, which pointed to correlation of these changes with the EP.

Wireless system for long-term EEG monitoring of absence epilepsy

NASA Astrophysics Data System (ADS)

Whitchurch, Ashwin K.; Ashok, B. H.; Kumaar, R. V.; Saurkesi, K.; Varadan, Vijay K.

2002-11-01

Absence epilepsy is a form of epilepsy common mostly in children. The most common manifestations of Absence epilepsy are staring and transient loss of responsiveness. Also, subtle motor activities may occur. Due to the subtle nature of these symptoms, episodes of absence epilepsy may often go unrecognized for long periods of time or be mistakenly attributed to attention deficit disorder or daydreaming. Spells of absence epilepsy may last about 10 seconds and occur hundreds of times each day. Patients have no recollections of the events that occurred during those seizures and will resume normal activity without any postictal symptoms. The EEG during such episodes of Absence epilepsy shows intermittent activity of 3 Hz generalized spike and wave complexes. As EEG is the only way of detecting such symptoms, it is required to monitor the EEG of the patient for a long time and thus remain only in bed. So, effectively the EEG is being monitored only when the patient is stationary. The wireless monitoring sys tem described in this paper aims at eliminating this constraint and enables the physicial to monitor the EEG when the patient resumes his normal activities. This approach could even help the doctor identify possible triggers of absence epilepsy.

Temporal coordination of olfactory cortex sharp-wave activity with up- and downstates in the orbitofrontal cortex during slow-wave sleep.

PubMed

Onisawa, Naomi; Manabe, Hiroyuki; Mori, Kensaku

2017-01-01

During slow-wave sleep, interareal communications via coordinated, slow oscillatory activities occur in the large-scale networks of the mammalian neocortex. Because olfactory cortex (OC) areas, which belong to paleocortex, show characteristic sharp-wave (SPW) activity during slow-wave sleep, we examined whether OC SPWs in freely behaving rats occur in temporal coordination with up- and downstates of the orbitofrontal cortex (OFC) slow oscillation. Simultaneous recordings of local field potentials and spike activities in the OC and OFC showed that during the downstate in the OFC, the OC also exhibited downstate with greatly reduced neuronal activity and suppression of SPW generation. OC SPWs occurred during two distinct phases of the upstate of the OFC: early-phase SPWs occurred at the start of upstate shortly after the down-to-up transition in the OFC, whereas late-phase SPWs were generated at the end of upstate shortly before the up-to-down transition. Such temporal coordination between neocortical up- and downstates and olfactory system SPWs was observed between the prefrontal cortex areas (OFC and medial prefrontal cortex) and the OC areas (anterior piriform cortex and posterior piriform cortex). These results suggest that during slow-wave sleep, OC and OFC areas communicate preferentially in specific time windows shortly after the down-to-up transition and shortly before the up-to-down transition. Simultaneous recordings of local field potentials and spike activities in the anterior piriform cortex (APC) and orbitofrontal cortex (OFC) during slow-wave sleep showed that APC sharp waves tended to occur during two distinct phases of OFC upstate: early phase, shortly after the down-to-up transition, and late phase, shortly before the up-to-down transition, suggesting that during slow-wave sleep, olfactory cortex and OFC areas communicate preferentially in the specific time windows. Copyright © 2017 the American Physiological Society.

The Antiepileptic Drug Levetiracetam Suppresses Non-Convulsive Seizure Activity and Reduces Ischemic Brain Damage in Rats Subjected to Permanent Middle Cerebral Artery Occlusion

PubMed Central

Cuomo, Ornella; Rispoli, Vincenzo; Leo, Antonio; Politi, Giovanni Bosco; Vinciguerra, Antonio; di Renzo, Gianfranco; Cataldi, Mauro

2013-01-01

The antiepileptic drug Levetiracetam (Lev) has neuroprotective properties in experimental stroke, cerebral hemorrhage and neurotrauma. In these conditions, non-convulsive seizures (NCSs) propagate from the core of the focal lesion into perilesional tissue, enlarging the damaged area and promoting epileptogenesis. Here, we explore whether Lev neuroprotective effect is accompanied by changes in NCS generation or propagation. In particular, we performed continuous EEG recordings before and after the permanent occlusion of the middle cerebral artery (pMCAO) in rats that received Lev (100 mg/kg) or its vehicle immediately before surgery. Both in Lev-treated and in control rats, EEG activity was suppressed after pMCAO. In control but not in Lev-treated rats, EEG activity reappeared approximately 30-45 min after pMCAO. It initially consisted in single spikes and, then, evolved into spike-and-wave and polyspike-and-wave discharges. In Lev-treated rats, only rare spike events were observed and the EEG power was significantly smaller than in controls. Approximately 24 hours after pMCAO, EEG activity increased in Lev-treated rats because of the appearance of polyspike events whose power was, however, significantly smaller than in controls. In rats sacrificed 24 hours after pMCAO, the ischemic lesion was approximately 50% smaller in Lev-treated than in control rats. A similar neuroprotection was observed in rats sacrificed 72 hours after pMCAO. In conclusion, in rats subjected to pMCAO, a single Lev injection suppresses NCS occurrence for at least 24 hours. This electrophysiological effect could explain the long lasting reduction of ischemic brain damage caused by this drug. PMID:24236205

Temporal coordination of olfactory cortex sharp-wave activity with up- and downstates in the orbitofrontal cortex during slow-wave sleep

PubMed Central

Onisawa, Naomi; Mori, Kensaku

2016-01-01

During slow-wave sleep, interareal communications via coordinated, slow oscillatory activities occur in the large-scale networks of the mammalian neocortex. Because olfactory cortex (OC) areas, which belong to paleocortex, show characteristic sharp-wave (SPW) activity during slow-wave sleep, we examined whether OC SPWs in freely behaving rats occur in temporal coordination with up- and downstates of the orbitofrontal cortex (OFC) slow oscillation. Simultaneous recordings of local field potentials and spike activities in the OC and OFC showed that during the downstate in the OFC, the OC also exhibited downstate with greatly reduced neuronal activity and suppression of SPW generation. OC SPWs occurred during two distinct phases of the upstate of the OFC: early-phase SPWs occurred at the start of upstate shortly after the down-to-up transition in the OFC, whereas late-phase SPWs were generated at the end of upstate shortly before the up-to-down transition. Such temporal coordination between neocortical up- and downstates and olfactory system SPWs was observed between the prefrontal cortex areas (OFC and medial prefrontal cortex) and the OC areas (anterior piriform cortex and posterior piriform cortex). These results suggest that during slow-wave sleep, OC and OFC areas communicate preferentially in specific time windows shortly after the down-to-up transition and shortly before the up-to-down transition. NEW & NOTEWORTHY Simultaneous recordings of local field potentials and spike activities in the anterior piriform cortex (APC) and orbitofrontal cortex (OFC) during slow-wave sleep showed that APC sharp waves tended to occur during two distinct phases of OFC upstate: early phase, shortly after the down-to-up transition, and late phase, shortly before the up-to-down transition, suggesting that during slow-wave sleep, olfactory cortex and OFC areas communicate preferentially in the specific time windows. PMID:27733591

Neural network classification of clinical neurophysiological data for acute care monitoring

NASA Technical Reports Server (NTRS)

Sgro, Joseph

1994-01-01

The purpose of neurophysiological monitoring of the 'acute care' patient is to allow the accurate recognition of changing or deteriorating neurological function as close to the moment of occurrence as possible, thus permitting immediate intervention. Results confirm that: (1) neural networks are able to accurately identify electroencephalogram (EEG) patterns and evoked potential (EP) wave components, and measuring EP waveform latencies and amplitudes; (2) neural networks are able to accurately detect EP and EEG recordings that have been contaminated by noise; (3) the best performance was obtained consistently with the back propagation network for EP and the HONN for EEG's; (4) neural network performed consistently better than other methods evaluated; and (5) neural network EEG and EP analyses are readily performed on multichannel data.

Change in the electroencephalogram delta wave in the frontal cranial region of rats with the hyperventilation.

PubMed

Kim, Young Sik; An, Sun Joung; Lee, Hu Jang; Choi, Hyun Ju

2012-04-30

Hyperventilation is one way to cause activation on the electroencephalogram (EEG) to diagnose brain disorders. The hyperventilation is also known to affect on the delta power in EEG. This study divided the total delta wave into low, middle, and high bands corresponding to the wave frequency. The power in these three delta wave bands was examined in the frontal cranial region of adult male Sprague-Dawley rats hyperventilated with ventilation (VE) of 360, 540, and 720 ml/min for 5 min. The control group was ventilated normally with a volume of 160 ml/min. The results show that the relative power of the low delta band in the rats hyperventilated at 360 ml/min VE was significantly increased compared with powers of pre-hyperventilation (p<0.05). The relative power of the middle delta band was not significantly affected by hyperventilation at any VE, and in the high delta band, all of the relative powers were decreased significantly in all hyperventilated rats compared with powers of pre-hyperventilation (p<0.05). We concluded that hyperventilation affects the frontal cranial region, by increasing the low delta band and decreasing the high delta band. Copyright © 2012 Elsevier B.V. All rights reserved.

Far-Field Noise Induced by Bubble near Free Surface

NASA Astrophysics Data System (ADS)

Ye, Xi; Li, Jiang-tao; Liu, Jian-hua; Chen, Hai-long

2018-03-01

The motion of a bubble near the free surface is solved by the boundary element method based on the linear wave equation, and the influence of fluid compressibility on bubble dynamics is analyzed. Based on the solution of the bubble motion, the far-field radiation noise induced by the bubble is calculated using Kirchhoff moving boundary integral equation, and the influence of free surface on far-field noise is researched. As the results, the oscillation amplitude of the bubble is weakened in compressible fluid compared with that in incompressible fluid, and the free surface amplifies the effect of fluid compressibility. When the distance between the bubble and an observer is much larger than that between the bubble and free surface, the sharp wave trough of the sound pressure at the observer occurs. With the increment of the distance between the bubble and free surface, the time of the wave trough appearing is delayed and the value of the wave trough increase. When the distance between the observer and the bubble is reduced, the sharp wave trough at the observer disappears.

Ballistocardiogram Artifact Removal with a Reference Layer and Standard EEG Cap

PubMed Central

Luo, Qingfei; Huang, Xiaoshan; Glover, Gary H.

2014-01-01

Background In simultaneous EEG-fMRI, the EEG recordings are severely contaminated by ballistocardiogram (BCG) artifacts, which are caused by cardiac pulsations. To reconstruct and remove the BCG artifacts, one promising method is to measure the artifacts in the absence of EEG signal by placing a group of electrodes (BCG electrodes) on a conductive layer (reference layer) insulated from the scalp. However, current BCG reference layer (BRL) methods either use a customized EEG cap composed of electrode pairs, or need to construct the custom reference layer through additional model-building experiments for each EEG-fMRI experiment. These requirements have limited the versatility and efficiency of BRL. The aim of this study is to propose a more practical and efficient BRL method and compare its performance with the most popular BCG removal method, the optimal basis sets (OBS) algorithm. New Method By designing the reference layer as a permanent and reusable cap, the new BRL method is able to be used with a standard EEG cap, and no extra experiments and preparations are needed to use the BRL in an EEG-fMRI experiment. Results The BRL method effectively removed the BCG artifacts from both oscillatory and evoked potential scalp recordings and recovered the EEG signal. Comparison with Existing Method Compared to the OBS, this new BRL method improved the contrast-to-noise ratios of the alpha-wave, visual, and auditory evoked potential signals by 101%, 76%, and 75% respectively, employing 160 BCG electrodes. Using only 20 BCG electrodes, the BRL improved the EEG signal by 74%/26%/41% respectively. Conclusion The proposed method can substantially improve the EEG signal quality compared with traditional methods. PMID:24960423

Restricting Time in Bed in Early Adolescence Reduces Both NREM and REM Sleep but Does Not Increase Slow Wave EEG

PubMed Central

Campbell, Ian G.; Kraus, Amanda M.; Burright, Christopher S.; Feinberg, Irwin

2016-01-01

Study Objectives: School night total sleep time decreases across adolescence (9–18 years) by 10 min/year. This decline is comprised entirely of a selective decrease in NREM sleep; REM sleep actually increases slightly. Decreasing sleep duration across adolescence is often attributed to insufficient time in bed. Here we tested whether sleep restriction in early adolescence produces the same sleep stage changes observed on school nights across adolescence. Methods: All-night sleep EEG was recorded in 76 children ranging in age from 9.9 to 14.0 years. Each participant kept 3 different sleep schedules that consisted of 3 nights of 8.5 h in bed followed by 4 nights of either 7, 8.5, or 10 h in bed. Sleep stage durations and NREM delta EEG activity were compared across the 3 time in bed conditions. Results: Shortening time in bed from 10 to 7 hours reduced sleep duration by approximately 2 hours, roughly equal to the decrease in sleep duration we recorded longitudinally across adolescence. However, sleep restriction significantly reduced both NREM (by 83 min) and REM (by 47 min) sleep. Sleep restriction did not affect NREM delta EEG activity. Conclusions: Our findings suggest that the selective NREM reduction and the small increase in REM we observed longitudinally across 9–18 years are not produced by sleep restriction. We hypothesize that the selective NREM decline reflects adolescent brain maturation (synaptic elimination) that reduces the need for the restorative processes of NREM sleep. Citation: Campbell IG, Kraus AM, Burright CS, Feinberg I. Restricting time in bed in early adolescence reduces both NREM and REM sleep but does not increase slow wave EEG. SLEEP 2016;39(9):1663–1670. PMID:27397569

Epileptic seizure prediction by non-linear methods

DOEpatents

Hively, Lee M.; Clapp, Ned E.; Daw, C. Stuart; Lawkins, William F.

1999-01-01

Methods and apparatus for automatically predicting epileptic seizures monitor and analyze brain wave (EEG or MEG) signals. Steps include: acquiring the brain wave data from the patient; digitizing the data; obtaining nonlinear measures of the data via chaotic time series analysis tools; obtaining time serial trends in the nonlinear measures; comparison of the trend to known seizure predictors; and providing notification that a seizure is forthcoming.

Design of an online EEG based neurofeedback game for enhancing attention and memory.

PubMed

Thomas, Kavitha P; Vinod, A P; Guan, Cuntai

2013-01-01

Brain-Computer Interface (BCI) is an alternative communication and control channel between brain and computer which finds applications in neuroprosthetics, brain wave controlled computer games etc. This paper proposes an Electroencephalogram (EEG) based neurofeedback computer game that allows the player to control the game with the help of attention based brain signals. The proposed game protocol requires the player to memorize a set of numbers in a matrix, and to correctly fill the matrix using his attention. The attention level of the player is quantified using sample entropy features of EEG. The statistically significant performance improvement of five healthy subjects after playing a number of game sessions demonstrates the effectiveness of the proposed game in enhancing their concentration and memory skills.

Observations of plan-view sand ripple behavior and spectral wave climate on the inner shelf of San Pedro Bay, California

USGS Publications Warehouse

Xu, J. P.

2005-01-01

Concurrent video images of sand ripples and current meter measurements of directional wave spectra are analyzed to study the relations between waves and wave-generated sand ripples. The data were collected on the inner shelf off Huntington Beach, California, at 15 m water depth, where the sea floor is comprised of well-sorted very fine sands (D50=92 ??m), during the winter of 2002. The wave climate, which was controlled by southerly swells (12-18 s period) and westerly wind waves (5-10 s period), included three wave types: (A) uni-modal, swells only; (B) bi-modal, swells dominant; and (C) bi-modal, wind-wave dominant. Each wave type has distinct relations with the plan-view shapes of ripples that are classified into five types: (1) sharp-crested, two-dimensional (2-D) ripples; (2) sharp-crested, brick-pattern, 3-D ripples; (3) bifurcated, 3-D ripples; (4) round-crested, shallow, 3-D ripples; and (5) flat bed. The ripple spacing is very small and varies between 4.5 and 7.5 cm. These ripples are anorbital as ripples in many field studies. Ripple orientation is only correlated with wave directions during strong storms (wave type C). In a poly-modal, multi-directional spectral wave environment, the use of the peak parameters (frequency, direction), a common practice when spectral wave measurements are unavailable, may lead to significant errors in boundary layer and sediment transport calculations. ?? 2004 Elsevier Ltd. All rights reserved.

Deciphering the role of CA1 inhibitory circuits in sharp wave-ripple complexes.

PubMed

Cutsuridis, Vassilis; Taxidis, Jiannis

2013-01-01

Sharp wave-ripples (SWRs) are population oscillatory patterns in hippocampal LFPs during deep sleep and immobility, involved in the replay of memories acquired during wakefulness. SWRs have been extensively studied, but their exact generation mechanism is still unknown. A computational model has suggested that fast perisomatic inhibition may generate the high frequency ripples (~200 Hz). Another model showed how replay of memories can be controlled by various classes of inhibitory interneurons targeting specific parts of pyramidal cells (PC) and firing at particular SWR phases. Optogenetic studies revealed new roles for interneuronal classes and rich dynamic interplays between them, shedding new light in their potential role in SWRs. Here, we integrate these findings in a conceptual model of how dendritic and somatic inhibition may collectively contribute to the SWR generation. We suggest that sharp wave excitation and basket cell (BC) recurrent inhibition synchronises BC spiking in ripple frequencies. This rhythm is imposed on bistratified cells which prevent pyramidal bursting. Axo-axonic and stratum lacunosum/moleculare interneurons are silenced by inhibitory inputs originating in the medial septum. PCs receiving rippling inhibition in both dendritic and perisomatic areas and excitation in their apical dendrites, exhibit sparse ripple phase-locked spiking.

Saccadic spike potentials in gamma-band EEG: characterization, detection and suppression.

PubMed

Keren, Alon S; Yuval-Greenberg, Shlomit; Deouell, Leon Y

2010-02-01

Analysis of high-frequency (gamma-band) neural activity by means of non-invasive EEG is gaining increasing interest. However, we have recently shown that a saccade-related spike potential (SP) seriously confounds the analysis of EEG induced gamma-band responses (iGBR), as the SP eludes traditional EEG artifact rejection methods. Here we provide a comprehensive profile of the SP and evaluate methods for its detection and suppression, aiming to unveil true cerebral gamma-band activity. The SP appears consistently as a sharp biphasic deflection of about 22 ms starting at the saccade onset, with a frequency band of approximately 20-90 Hz. On the average, larger saccades elicit higher SP amplitudes. The SP amplitude gradually changes from the extra-ocular channels towards posterior sites with the steepest gradients around the eyes, indicating its ocular source. Although the amplitude and the sign of the SP depend on the choice of reference channel, the potential gradients remain the same and non-zero for all references. The scalp topography is modulated almost exclusively by the direction of saccades, with steeper gradients ipsilateral to the saccade target. We discuss how the above characteristics impede attempts to remove these SPs from the EEG by common temporal filtering, choice of different references, or rejection of contaminated trials. We examine the extent to which SPs can be reliably detected without an eye tracker, assess the degree to which scalp current density derivation attenuates the effect of the SP, and propose a tailored ICA procedure for minimizing the effect of the SP. Copyright (c) 2009 Elsevier Inc. All rights reserved.

Electroencephalographic characteristics of Iranian schizophrenia patients.

PubMed

Chaychi, Irman; Foroughipour, Mohsen; Haghir, Hossein; Talaei, Ali; Chaichi, Ashkan

2015-12-01

Schizophrenia is a prevalent psychiatric disease with heterogeneous causes that is diagnosed based on history and mental status examination. Applied electrophysiology is a non-invasive method to investigate the function of the involved brain areas. In a previously understudied population, we examined acute phase electroencephalography (EEG) records along with pertinent Positive and Negative Syndrome Scale (PANSS) and Mini Mental State Examination (MMSE) scores for each patient. Sixty-four hospitalized patients diagnosed to have schizophrenia in Ebn-e-Sina Hospital were included in this study. PANSS and MMSE were completed and EEG tracings for every patient were recorded. Also, EEG tracings were recorded for 64 matched individuals of the control group. Although the predominant wave pattern in both patients and controls was alpha, theta waves were almost exclusively found in eight (12.5 %) patients with schizophrenia. Pathological waves in schizophrenia patients were exclusively found in the frontal brain region, while identified pathological waves in controls were limited to the temporal region. No specific EEG finding supported laterality in schizophrenia patients. PANSS and MMSE scores were significantly correlated with specific EEG parameters (all P values <0.04). Patients with schizophrenia demonstrate specific EEG patterns and show a clear correlation between EEG parameters and PANSS and MMSE scores. These characteristics are not observed in all patients, which imply that despite an acceptable specificity, they are not applicable for the majority of schizophrenia patients. Any deduction drawn based on EEG and scoring systems is in need of larger studies incorporating more patients and using better functional imaging techniques for the brain.

Computational Electromagnetic Analysis in a Human Head Model with EEG Electrodes and Leads Exposed to RF-Field Sources at 915 MHz and 1748 MHz

PubMed Central

Angelone, Leonardo M.; Bit-Babik, Giorgi; Chou, Chung-Kwang

2010-01-01

An electromagnetic analysis of a human head with EEG electrodes and leads exposed to RF-field sources was performed by means of Finite-Difference Time-Domain simulations on a 1-mm3 MRI-based human head model. RF-field source models included a half-wave dipole, a patch antenna, and a realistic CAD-based mobile phone at 915 MHz and 1748 MHz. EEG electrodes/leads models included two configurations of EEG leads, both a standard 10–20 montage with 19 electrodes and a 32-electrode cap, and metallic and high resistive leads. Whole-head and peak 10-g average SAR showed less than 20% changes with and without leads. Peak 1-g and 10-g average SARs were below the ICNIRP and IEEE guideline limits. Conversely, a comprehensive volumetric assessment of changes in the RF field with and without metallic EEG leads showed an increase of two orders of magnitude in single-voxel power absorption in the epidermis and a 40-fold increase in the brain during exposure to the 915 MHz mobile phone. Results varied with the geometry and conductivity of EEG electrodes/leads. This enhancement confirms the validity of the question whether any observed effects in studies involving EEG recordings during RF-field exposure are directly related to the RF fields generated by the source or indirectly to the RF-field-induced currents due to the presence of conductive EEG leads. PMID:20681803

EEG phase reset due to auditory attention: an inverse time-scale approach.

PubMed

Low, Yin Fen; Strauss, Daniel J

2009-08-01

We propose a novel tool to evaluate the electroencephalograph (EEG) phase reset due to auditory attention by utilizing an inverse analysis of the instantaneous phase for the first time. EEGs were acquired through auditory attention experiments with a maximum entropy stimulation paradigm. We examined single sweeps of auditory late response (ALR) with the complex continuous wavelet transform. The phase in the frequency band that is associated with auditory attention (6-10 Hz, termed as theta-alpha border) was reset to the mean phase of the averaged EEGs. The inverse transform was applied to reconstruct the phase-modified signal. We found significant enhancement of the N100 wave in the reconstructed signal. Analysis of the phase noise shows the effects of phase jittering on the generation of the N100 wave implying that a preferred phase is necessary to generate the event-related potential (ERP). Power spectrum analysis shows a remarkable increase of evoked power but little change of total power after stabilizing the phase of EEGs. Furthermore, by resetting the phase only at the theta border of no attention data to the mean phase of attention data yields a result that resembles attention data. These results show strong connections between EEGs and ERP, in particular, we suggest that the presentation of an auditory stimulus triggers the phase reset process at the theta-alpha border which leads to the emergence of the N100 wave. It is concluded that our study reinforces other studies on the importance of the EEG in ERP genesis.

[Electroencephalographic characteristics of the deja vu phenomenon].

PubMed

Vlasov, P N; Cherviakov, A V; Gnezdinsiĭ, V V

2013-01-01

Déjà vu (DV, from French "already seen") is an aberration of psychic activity associated with transitory erroneous perception of novel circumstances, objects, or people as already known. An aim of the study was to investigate EEG characteristics of DV in patients with epilepsy. We studied 166 people (63.2% women, mean age 25.17±9.19 years). The DV phenomenon was studied in patients (27 people) and in a control group (139 healthy people). Patients were interviewed for DV characteristics and underwent a long (12-16 h) ambulatory EEG-monitoring study. In EEG, DV episodes in patients began with polyspike activity in the right temporal lobe and, in some cases, ended with the slow-wave theta-delta activity in the right hemisphere.

Different quantitative EEG alterations induced by TBI among patients with different APOE genotypes.

PubMed

Jiang, Li; Yin, Xiaohong; Yin, Cheng; Zhou, Shuai; Dan, Wei; Sun, Xiaochuan

2011-11-14

Although several studies have revealed the EEG alterations in AD and TBI patients, the influence of APOE (apolipoprotein E) genotype in EEG at the early stage of TBI has not been reported yet. We have previously studied EEG alterations caused by TBI among different APOE genotype carriers. In this study, we firstly investigated the relationship between APOE polymorphisms and quantitative EEG (QEEG) changes after TBI. A total of 118 consecutive TBI patients with a Glasgow Coma Scale (GCS) of 9 or higher were recruited, and 40 normal adults were also included as a control group. APOE genotype was determined by PCR-RFLP for each subject, and QEEG recordings were performed in rest, relaxed, awake and with eyes closed in normal subjects and TBI patients during 1-3 days after TBI. In the normal control group, both APOEɛ4 carriers and non-carriers had normal EEG, and no significant difference of QEEG data was found between APOEɛ4 carriers and non-carriers. But in the TBI group, APOEɛ4 carriers had more focal or global irregular slow wave activities than APOEɛ4 non-carriers. APOE gene did not influence brain electrical activity under normal conditions, but TBI can induce different alterations among different APOE gene carriers, and APOEɛ4 allele enhances the EEG abnormalities at the early stage of TBI. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Bispectral index monitoring during electroconvulsive therapy under propofol anaesthesia.

PubMed

Gunawardane, P O; Murphy, P A; Sleigh, J W

2002-02-01

The accuracy of the bispectral index (BIS) as a monitor of consciousness has not been well studied in patients who have abnormal electroencephalograms (EEG). We studied the changes in BIS, its subparameters, and spectral entropy of the EEG during 18 electroconvulsive treatments under propofol and succinylcholine anaesthesia. A single bifrontal EEG, and second subocular channel (for eye movement estimation) was recorded. The median (interquartile range) BIS value at re-awakening was only 57 (47-78)--thus more than a quarter of the patients woke at BIS values of less than 50. The changes in spectral entropy values were similar: 0.84 (0.68-0.99) at the start, 0.65 (0.42-0.88) at the point of loss-of-consciousness, 0.63 (0.47-0.79) during the seizures, and 0.58 (0.31-0.85) at awakening. Post-ictal slow-wave activity in the EEG (acting via the SynchFastSlow subparameter) may cause low BIS values that do not correspond to the patient's clinical level of consciousness. This may be important in the interpretation of the BIS in other groups of patients who have increased delta-band power in their EEG.

Material and physical model for evaluation of deep brain activity contribution to EEG recordings

NASA Astrophysics Data System (ADS)

Ye, Yan; Li, Xiaoping; Wu, Tiecheng; Li, Zhe; Xie, Wenwen

2015-12-01

Deep brain activity is conventionally recorded with surgical implantation of electrodes. During the neurosurgery, brain tissue damage and the consequent side effects to patients are inevitably incurred. In order to eliminate undesired risks, we propose that deep brain activity should be measured using the noninvasive scalp electroencephalography (EEG) technique. However, the deeper the neuronal activity is located, the noisier the corresponding scalp EEG signals are. Thus, the present study aims to evaluate whether deep brain activity could be observed from EEG recordings. In the experiment, a three-layer cylindrical head model was constructed to mimic a human head. A single dipole source (sine wave, 10 Hz, altering amplitudes) was embedded inside the model to simulate neuronal activity. When the dipole source was activated, surface potential was measured via electrodes attached on the top surface of the model and raw data were recorded for signal analysis. Results show that the dipole source activity positioned at 66 mm depth in the model, equivalent to the depth of deep brain structures, is clearly observed from surface potential recordings. Therefore, it is highly possible that deep brain activity could be observed from EEG recordings and deep brain activity could be measured using the noninvasive scalp EEG technique.

A method for the topographical identification and quantification of high frequency oscillations in intracranial electroencephalography recordings

PubMed Central

Waldman, Zachary J.; Shimamoto, Shoichi; Song, Inkyung; Orosz, Iren; Bragin, Anatol; Fried, Itzhak; Engel, Jerome; Staba, Richard; Sperling, Michael R.; Weiss, Shennan A.

2018-01-01

Objective To develop a reliable software method using a topographic analysis of time-frequency plots to distinguish ripple (80–200 Hz) oscillations that are often associated with EEG sharp waves or spikes (RonS) from sinusoid-like waveforms that appear as ripples but correspond with digital filtering of sharp transients contained in the wide bandwidth EEG. Methods A custom algorithm distinguished true from false ripples in one second intracranial EEG (iEEG) recordings using wavelet convolution, identifying contours of isopower, and categorizing these contours into sets of open or closed loop groups. The spectral and temporal features of candidate groups were used to classify the ripple, and determine its duration, frequency, and power. Verification of detector accuracy was performed on the basis of simulations, and visual inspection of the original and band-pass filtered signals. Results The detector could distinguish simulated true from false ripple on spikes (RonS). Among 2934 visually verified trials of iEEG recordings and spectrograms exhibiting RonS the accuracy of the detector was 88.5% with a sensitivity of 81.8% and a specificity of 95.2%. The precision was 94.5% and the negative predictive value was 84.0% (N = 12). Among, 1,370 trials of iEEG recording exhibiting RonS that were reviewed blindly without spectrograms the accuracy of the detector was 68.0%, with kappa equal to 0.01 ± 0.03. The detector successfully distinguished ripple from high spectral frequency ‘fast ripple’ oscillations (200–600 Hz), and characterize ripple duration and spectral frequency and power. The detector was confounded by brief bursts of gamma (30–80 Hz) activity in 7.31 ± 6.09% of trials, and in 30.2 ± 14.4% of the true RonS detections ripple duration was underestimated. Conclusions Characterizing the topographic features of a time-frequency plot generated by wavelet convolution is useful for distinguishing true oscillations from false oscillations generated by filter ringing. Significance Categorizing ripple oscillations and characterizing their properties can improve the clinical utility of the biomarker. PMID:29122445

An experimental study of three-dimensional shock wave/boundary layer interactions generated by sharp fins

NASA Technical Reports Server (NTRS)

Lu, F. K.; Settles, G. S.; Bogdonoff, S. M.

1983-01-01

The interaction between a turbulent boundary layer and a shock wave generated by a sharp fin with leading edge sweepback was investigated. The incoming flow was at Mach 2.96 and at a unit Reynolds number of 63 x 10 to the 6th power 0.1 m. The approximate incoming boundary layer thickness was either 4 mm or 17 mm. The fins used were at 5 deg, 9 deg and 15 deg incidence and had leading edge sweepback from 0 deg to 65 deg. The tests consisted of surface kerosene lampblack streak visualization, surface pressure measurements, shock wave shape determination by shadowgraphs, and localized vapor screen visualization. The upstream influence lengths of the fin interactions were correlated using viscous and inviscid flow parameters. The parameters affecting the surface features close to the fin and way from the fin were also identified. Essentially, the surface features in the farfield were found to be conical.

Magnetocardiography and magnetoencephalography measurements at room temperature using tunnel magneto-resistance sensors

NASA Astrophysics Data System (ADS)

Fujiwara, Kosuke; Oogane, Mikihiko; Kanno, Akitake; Imada, Masahiro; Jono, Junichi; Terauchi, Takashi; Okuno, Tetsuo; Aritomi, Yuuji; Morikawa, Masahiro; Tsuchida, Masaaki; Nakasato, Nobukazu; Ando, Yasuo

2018-02-01

Magnetocardiography (MCG) and magnetoencephalography (MEG) signals were detected at room temperature using tunnel magneto-resistance (TMR) sensors. TMR sensors developed with low-noise amplifier circuits detected the MCG R wave without averaging, and the QRS complex was clearly observed with averaging at a high signal-to-noise ratio. Spatial mapping of the MCG was also achieved. Averaging of MEG signals triggered by electroencephalography (EEG) clearly observed the phase inversion of the alpha rhythm with a correlation coefficient as high as 0.7 between EEG and MEG.

Acquired auditory agnosia in childhood and normal sleep electroencephalography subsequently diagnosed as Landau-Kleffner syndrome: a report of three cases.

PubMed

van Bogaert, Patrick; King, Mary D; Paquier, Philippe; Wetzburger, Catherine; Labasse, Catherine; Dubru, Jean-Marie; Deonna, Thierry

2013-06-01

  We report three cases of Landau-Kleffner syndrome (LKS) in children (two females, one male) in whom diagnosis was delayed because the sleep electroencephalography (EEG) was initially normal.   Case histories including EEG, positron emission tomography findings, and long-term outcome were reviewed.   Auditory agnosia occurred between the age of 2 years and 3 years 6 months, after a period of normal language development. Initial awake and sleep EEG, recorded weeks to months after the onset of language regression, during a nap period in two cases and during a full night of sleep in the third case, was normal. Repeat EEG between 2 months and 2 years later showed epileptiform discharges during wakefulness and strongly activated by sleep, with a pattern of continuous spike-waves during slow-wave sleep in two patients. Patients were diagnosed with LKS and treated with various antiepileptic regimens, including corticosteroids. One patient in whom EEG became normal on hydrocortisone is making significant recovery. The other two patients did not exhibit a sustained response to treatment and remained severely impaired.   Sleep EEG may be normal in the early phase of acquired auditory agnosia. EEG should be repeated frequently in individuals in whom a firm clinical diagnosis is made to facilitate early treatment. © The Authors. Developmental Medicine & Child Neurology © 2012 Mac Keith Press.

Electron attachment in F2 - Conclusive demonstration of nonresonant, s-wave coupling in the limit of zero electron energy

NASA Technical Reports Server (NTRS)

Chutjian, A.; Alajajian, S. H.

1987-01-01

Dissociative electron attachment to F2 has been observed in the energy range 0-140 meV, at a resolution of 6 meV (full width at half maximum). Results show conclusively a sharp, resolution-limited threshold behavior consistent with an s-wave cross section varying as sq rt of epsilon. Two accurate theoretical calculations predict only p-wave behavior varying as the sq rt of epsilon. Several nonadiabatic coupling effects leading to s-wave behavior are outlined.

Integrating EEG and fMRI in epilepsy.

PubMed

Formaggio, Emanuela; Storti, Silvia Francesca; Bertoldo, Alessandra; Manganotti, Paolo; Fiaschi, Antonio; Toffolo, Gianna Maria

2011-02-14

Integrating electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) studies enables to non-invasively investigate human brain function and to find the direct correlation of these two important measures of brain activity. Presurgical evaluation of patients with epilepsy is one of the areas where EEG and fMRI integration has considerable clinical relevance for localizing the brain regions generating interictal epileptiform activity. The conventional analysis of EEG-fMRI data is based on the visual identification of the interictal epileptiform discharges (IEDs) on scalp EEG. The convolution of these EEG events, represented as stick functions, with a model of the fMRI response, i.e. the hemodynamic response function, provides the regressor for general linear model (GLM) analysis of fMRI data. However, the conventional analysis is not automatic and suffers of some subjectivity in IEDs classification. Here, we present an easy-to-use and automatic approach for combined EEG-fMRI analysis able to improve IEDs identification based on Independent Component Analysis and wavelet analysis. EEG signal due to IED is reconstructed and its wavelet power is used as a regressor in GLM. The method was validated on simulated data and then applied on real data set consisting of 2 normal subjects and 5 patients with partial epilepsy. In all continuous EEG-fMRI recording sessions a good quality EEG was obtained allowing the detection of spontaneous IEDs and the analysis of the related BOLD activation. The main clinical finding in EEG-fMRI studies of patients with partial epilepsy is that focal interictal slow-wave activity was invariably associated with increased focal BOLD responses in a spatially related brain area. Our study extends current knowledge on epileptic foci localization and confirms previous reports suggesting that BOLD activation associated with slow activity might have a role in localizing the epileptogenic region even in the absence of clear interictal spikes. Copyright © 2010 Elsevier Inc. All rights reserved.

[The mechanism and function of hippocampal neural oscillation].

PubMed

Lu, Ning; Xing, Dan-Qin; Sheng, Tao; Lu, Wei

2017-10-25

Neural oscillation is rhythmic or repetitive neural activity in the central nervous system that is usually generated by oscillatory activity of neuronal ensembles, reflecting regular and synchronized activities within these cell populations. According to several oscillatory bands covering frequencies from approximately 0.5 Hz to >100 Hz, neural oscillations are usually classified as delta oscillation (0.5-3 Hz), theta oscillation (4-12 Hz), beta oscillation (12-30 Hz), gamma oscillation (30-100 Hz) and sharp-wave ripples (>100 Hz ripples superimposed on 0.01-3 Hz sharp waves). Neural oscillation in different frequencies can be detected in different brain regions of human and animal during perception, motion and sleep, and plays an essential role in cognition, learning and memory process. In this review, we summarize recent findings on neural oscillations in hippocampus, as well as the mechanism and function of hippocampal theta oscillation, gamma oscillation and sharp-wave ripples. This review may yield new insights into the functions of neural oscillation in general.

Study of hydrodynamic characteristics of a Sharp Eagle wave energy converter

NASA Astrophysics Data System (ADS)

Zhang, Ya-qun; Sheng, Song-wei; You, Ya-ge; Huang, Zhen-xin; Wang, Wen-sheng

2017-06-01

According to Newton's Second Law and the microwave theory, mechanical analysis of multiple buoys which form Sharp Eagle wave energy converter (WEC) is carried out. The movements of every buoy in three modes couple each other when they are affected with incident waves. Based on the above, mechanical models of the WEC are established, which are concerned with fluid forces, damping forces, hinge forces, and so on. Hydrodynamic parameters of one buoy are obtained by taking the other moving buoy as boundary conditions. Then, by taking those hydrodynamic parameters into the mechanical models, the optimum external damping and optimal capture width ratio are calculated out. Under the condition of the optimum external damping, a plenty of data are obtained, such as the displacements amplitude of each buoy in three modes (sway, heave, pitch), damping forces, hinge forces, and speed of the hydraulic cylinder. Research results provide theoretical references and basis for Sharp Eagle WECs in the design and manufacture.

Universal potential-barrier penetration by initially confined wave packets

NASA Astrophysics Data System (ADS)

Granot, Er'El; Marchewka, Avi

2007-07-01

The dynamics of an initially sharp-boundary wave packet in the presence of an arbitrary potential barrier is investigated. It is shown that the penetration through the barrier is universal in the sense that it depends only on the values of the wave function and its derivatives at the boundary. The dependence on the derivatives vanishes at long distances from the barrier, where the dynamics is governed solely by the initial value of the wave function at the boundary.

EEG Negativity in Fixations Used for Gaze-Based Control: Toward Converting Intentions into Actions with an Eye-Brain-Computer Interface

PubMed Central

Shishkin, Sergei L.; Nuzhdin, Yuri O.; Svirin, Evgeny P.; Trofimov, Alexander G.; Fedorova, Anastasia A.; Kozyrskiy, Bogdan L.; Velichkovsky, Boris M.

2016-01-01

We usually look at an object when we are going to manipulate it. Thus, eye tracking can be used to communicate intended actions. An effective human-machine interface, however, should be able to differentiate intentional and spontaneous eye movements. We report an electroencephalogram (EEG) marker that differentiates gaze fixations used for control from spontaneous fixations involved in visual exploration. Eight healthy participants played a game with their eye movements only. Their gaze-synchronized EEG data (fixation-related potentials, FRPs) were collected during game's control-on and control-off conditions. A slow negative wave with a maximum in the parietooccipital region was present in each participant's averaged FRPs in the control-on conditions and was absent or had much lower amplitude in the control-off condition. This wave was similar but not identical to stimulus-preceding negativity, a slow negative wave that can be observed during feedback expectation. Classification of intentional vs. spontaneous fixations was based on amplitude features from 13 EEG channels using 300 ms length segments free from electrooculogram contamination (200–500 ms relative to the fixation onset). For the first fixations in the fixation triplets required to make moves in the game, classified against control-off data, a committee of greedy classifiers provided 0.90 ± 0.07 specificity and 0.38 ± 0.14 sensitivity. Similar (slightly lower) results were obtained for the shrinkage Linear Discriminate Analysis (LDA) classifier. The second and third fixations in the triplets were classified at lower rate. We expect that, with improved feature sets and classifiers, a hybrid dwell-based Eye-Brain-Computer Interface (EBCI) can be built using the FRP difference between the intended and spontaneous fixations. If this direction of BCI development will be successful, such a multimodal interface may improve the fluency of interaction and can possibly become the basis for a new input device for paralyzed and healthy users, the EBCI “Wish Mouse.” PMID:27917105

Epileptic seizure prediction by non-linear methods

DOEpatents

Hively, L.M.; Clapp, N.E.; Day, C.S.; Lawkins, W.F.

1999-01-12

This research discloses methods and apparatus for automatically predicting epileptic seizures monitor and analyze brain wave (EEG or MEG) signals. Steps include: acquiring the brain wave data from the patient; digitizing the data; obtaining nonlinear measures of the data via chaotic time series analysis tools; obtaining time serial trends in the nonlinear measures; comparison of the trend to known seizure predictors; and providing notification that a seizure is forthcoming. 76 figs.

Axonal properties determine somatic firing in a model of in vitro CA1 hippocampal sharp wave/ripples and persistent gamma oscillations

PubMed Central

Traub, Roger D.; Schmitz, Dietmar; Maier, Nikolaus; Whittington, Miles A.; Draguhn, Andreas

2012-01-01

Evidence has been presented that CA1 pyramidal cells, during spontaneous in vitro sharp wave/ripple (SPW-R) complexes, generate somatic action potentials that originate in axons. ‘Participating’ (somatically firing) pyramidal cells fire (almost always) at most once during a particular SPW-R whereas non-participating cells virtually never fire during an SPW-R. Somatic spikelets were small or absent, while ripple-frequency EPSCs and IPSCs occurred during the SPW-R in pyramidal neurons. These experimental findings could be replicated with a network model in which electrical coupling was present between small pyramidal cell axonal branches. Here, we explore this model in more depth. Factors that influence somatic participation include: (i) the diameter of axonal branches that contain coupling sites to other axons, because firing in larger branches injects more current into the main axon, increasing antidromic firing probability; (ii) axonal K+ currents; and (iii) somatic hyperpolarization and shunting. We predict that portions of axons fire at high frequency during SPW-R, while somata fire much less. In the model, somatic firing can occur by occasional generation of full action potentials in proximal axonal branches, which are excited by high-frequency spikelets. When the network contains phasic synaptic inhibition, at the axonal gap junction site, gamma oscillations result, again with more frequent axonal firing than somatic firing. Combining the models, so as to generate gamma followed by sharp waves, leads to strong overlap between the population of cells firing during gamma the population of cells firing during a subsequent sharp wave, as observed in vivo. PMID:22697272

Coordinated Interaction between Hippocampal Sharp-Wave Ripples and Anterior Cingulate Unit Activity

PubMed Central

2016-01-01

Hippocampal–cortical interaction during sleep promotes transformation of memory for long-term storage in the cortex. In particular, hippocampal sharp-wave ripple-associated neural activation is important for this transformation during slow-wave sleep. The anterior cingulate cortex (ACC) has been shown to be crucial for expression and likely storage of long-term memory. However, little is known about how ACC activity is influenced by hippocampal ripple activity during sleep. We report here about coordinated interactions between hippocampal ripple activity and ACC neural firings. By recording from the ACC and hippocampal CA1 simultaneously in mice, we found that almost all ACC neurons showed increased activity before hippocampal ripple activity; moreover, a subpopulation (17%) displayed a further activation immediately after ripple activity. This postripple activation of ACC neurons correlated positively with ripple amplitude, and the same neurons were excited upon electrical stimulation of the CA1. Interestingly, the preripple activation of ACC neurons was present during the sleep state, but not during the awake state. These results suggest intimate interactions between hippocampal sharp-wave ripples and ACC neurons in a state-dependent manner. Importantly, sharp-wave ripples and associated activation appear to regulate activity of a small population of ACC neurons, a process that may play a critical role in memory consolidation. SIGNIFICANCE STATEMENT The hippocampus communicates with the cortex for memory transformation. Memories of previous experiences become less dependent on the hippocampus and increasingly dependent on cortical areas, such as the anterior cingulate cortex (ACC). However, little evidence is available to directly support this hippocampus-to-cortex information transduction hypothesis of memory consolidation. Here we show that a subpopulation of ACC neurons becomes active just after hippocampal ripple activity, and that electrical stimulation of the hippocampus excites the same ACC neurons. In addition, the majority of ACC neurons are activated just before ripple activity during the sleep state, but not during the awake state. These results provide evidence supporting the hypothesis of hippocampus-to-cortex information flow for memory consolidation as well as reciprocal interaction between the hippocampus and the cortex. PMID:27733616

The contribution of posterior circulation to memory function during the intracarotid amobarbital procedure.

PubMed

Zijlmans, M; Huibers, C J A; Huiskamp, G J; de Kort, G A P; Alpherts, W C J; Leijten, F S S; Hendrikse, J

2012-08-01

The purpose of this study was to evaluate the contribution of posterior circulation to memory function by comparing memory scores between patients with and without a foetal-type posterior cerebral artery (FTP) during the intracarotid amobarbital procedure (IAP) in epilepsy patients. Patients undergoing bilateral IAP between January 2004 and January 2010 were retrospectively included. Pre-test angiograms were assessed for the presence of a FTP. Memory function scores (% correct) after right and left injections were obtained. Functional significance of FTP was affirmed by relative occipital versus parietal EEG slow-wave increase during IAP. Memory and EEG scores were compared between patients with and without FTP (Mann-Whitney U test). A total of 106 patients were included, 73 with posterior cerebral arteries (PCA) without FTP ('non-FTP'), 28 patients with unilateral FTP and 5 with a bilateral FTP. Memory scores were lower when amytal was injected to the hemisphere contralateral to the presumed seizure focus (on the right decreasing from 98.3 to 59.1, and on the left decreasing from 89.1 to 72.4; p < 0.001). When IAP was performed on the side of FTP memory scores were significantly lower (70.8) compared to non-FTP (82.0; p = 0.02). Relative occipital EEG changes were 0.44 for FTP cases and 0.36 for non-FTP patients (p = 0.01). A relationship between vasculature and brain function was demonstrated by lower memory scores and more slow-wave activity on occipital EEG during IAP in patients with foetal-type PCA compared to patients with non-FTP. This suggests an important contribution of brain areas supplied by the PCA to memory function.

Identifying stereotypic evolving micro-scale seizures (SEMS) in the hypoxic-ischemic EEG of the pre-term fetal sheep with a wavelet type-II fuzzy classifier.

PubMed

Abbasi, Hamid; Bennet, Laura; Gunn, Alistair J; Unsworth, Charles P

2016-08-01

Perinatal hypoxic-ischemic encephalopathy (HIE) around the time of birth due to lack of oxygen can lead to debilitating neurological conditions such as epilepsy and cerebral palsy. Experimental data have shown that brain injury evolves over time, but during the first 6-8 hours after HIE the brain has recovered oxidative metabolism in a latent phase, and brain injury is reversible. Treatments such as therapeutic cerebral hypothermia (brain cooling) are effective when started during the latent phase, and continued for several days. Effectiveness of hypothermia is lost if started after the latent phase. Post occlusion monitoring of particular micro-scale transients in the hypoxic-ischemic (HI) Electroencephalogram (EEG), from an asphyxiated fetal sheep model in utero, could provide precursory evidence to identify potential biomarkers of injury when brain damage is still treatable. In our studies, we have reported how it is possible to automatically detect HI EEG transients in the form of spikes and sharp waves during the latent phase of the HI EEG of the preterm fetal sheep. This paper describes how to identify stereotypic evolving micro-scale seizures (SEMS) which have a relatively abrupt onset and termination in a frequency range of 1.8-3Hz (Delta waves) superimposed on a suppressed EEG amplitude background post occlusion. This research demonstrates how a Wavelet Type-II Fuzzy Logic System (WT-Type-II-FLS) can be used to automatically identify subtle abnormal SEMS that occur during the latent phase with a preliminary average validation overall performance of 78.71%±6.63 over the 390 minutes of the latent phase, post insult, using in utero pre-term hypoxic fetal sheep models.

Continuous EEG-fMRI in Pre-Surgical Evaluation of a Patient with Symptomatic Seizures: Bold Activation Linked to Interictal Epileptic Discharges Caused by Cavernoma.

PubMed

Avesani, M; Formaggio, E; Milanese, F; Baraldo, A; Gasparini, A; Cerini, R; Bongiovanni, L G; Pozzi Mucelli, R; Fiaschi, A; Manganotti, P

2008-04-07

We used continuous electroencephalography-functional magnetic resonance imaging (EEG-fMRI) to identify the linkage between the "epileptogenic" and the "irritative" area in a patient with symptomatic epilepsy (cavernoma, previously diagnosed and surgically treated), i.e. a patient with a well known "epileptogenic area", and to increase the possibility of a non invasive pre-surgical evaluation of drug-resistant epilepsies. A compatible MRI system was used (EEG with 29 scalp electrodes and two electrodes for ECG and EMG) and signals were recorded with a 1.5 Tesla MRI scanner. After the recording session and MRI artifact removal, EEG data were analyzed offline and used as paradigms in fMRI study. Activation (EEG sequences with interictal slow-spiked-wave activity) and rest (sequences of normal EEG) conditions were compared to identify the potential resulting focal increase in BOLD signal and to consider if this is spatially linked to the interictal focus used as a paradigm and to the lesion. We noted an increase in the BOLD signal in the left neocortical temporal region, laterally and posteriorly to the poro-encephalic cavity (residual of cavernoma previously removed), that is around the "epileptogenic area". In our study "epileptogenic" and "irritative" areas were connected with each other. Combined EEG-fMRI may become routine in clinical practice for a better identification of an irritative and lesional focus in patients with symptomatic drug-resistant epilepsy.

Apparatus and method for epileptic seizure detection using non-linear techniques

DOEpatents

Hively, Lee M.; Clapp, Ned E.; Daw, C. Stuart; Lawkins, William F.

1998-01-01

Methods and apparatus for automatically detecting epileptic seizures by monitoring and analyzing brain wave (EEG or MEG) signals. Steps include: acquiring the brain wave data from the patient; digitizing the data; obtaining nonlinear measures of the data via chaotic time series analysis; obtaining time serial trends in the nonlinear measures; determining that one or more trends in the nonlinear measures indicate a seizure, and providing notification of seizure occurrence.

Voluntary Sleep Loss in Rats.

PubMed

Oonk, Marcella; Krueger, James M; Davis, Christopher J

2016-07-01

Animal sleep deprivation (SDEP), in contrast to human SDEP, is involuntary and involves repeated exposure to aversive stimuli including the inability of the animal to control the waking stimulus. Therefore, we explored intracranial self-stimulation (ICSS), an operant behavior, as a method for voluntary SDEP in rodents. Male Sprague-Dawley rats were implanted with electroencephalography/electromyography (EEG/EMG) recording electrodes and a unilateral bipolar electrode into the lateral hypothalamus. Rats were allowed to self-stimulate, or underwent gentle handling-induced SDEP (GH-SDEP), during the first 6 h of the light phase, after which they were allowed to sleep. Other rats performed the 6 h ICSS and 1 w later were subjected to 6 h of noncontingent stimulation (NCS). During NCS the individual stimulation patterns recorded during ICSS were replayed. After GH-SDEP, ICSS, or NCS, time in nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep increased. Further, in the 24 h after SDEP, rats recovered all of the REM sleep lost during SDEP, but only 75% to 80% of the NREM sleep lost, regardless of the SDEP method. The magnitude of EEG slow wave responses occurring during NREM sleep also increased after SDEP treatments. However, NREM sleep EEG slow wave activity (SWA) responses were attenuated following ICSS, compared to GH-SDEP and NCS. We conclude that ICSS and NCS can be used to sleep deprive rats. Changes in rebound NREM sleep EEG SWA occurring after ICSS, NCS, and GH-SDEP suggest that nonspecific effects of the SDEP procedure differentially affect recovery sleep phenotypes. © 2016 Associated Professional Sleep Societies, LLC.

Prediction of rhythmic and periodic EEG patterns and seizures on continuous EEG with early epileptiform discharges.

PubMed

Koren, J; Herta, J; Draschtak, S; Pötzl, G; Pirker, S; Fürbass, F; Hartmann, M; Kluge, T; Baumgartner, C

2015-08-01

Continuous EEG (cEEG) is necessary to document nonconvulsive seizures (NCS), nonconvulsive status epilepticus (NCSE), as well as rhythmic and periodic EEG patterns of 'ictal-interictal uncertainty' (RPPIIU) including periodic discharges, rhythmic delta activity, and spike-and-wave complexes in neurological intensive care patients. However, cEEG is associated with significant recording and analysis efforts. Therefore, predictors from short-term routine EEG with a reasonably high yield are urgently needed in order to select patients for evaluation with cEEG. The aim of this study was to assess the prognostic significance of early epileptiform discharges (i.e., within the first 30 min of EEG recording) on the following: (1) incidence of ictal EEG patterns and RPPIIU on subsequent cEEG, (2) occurrence of acute convulsive seizures during the ICU stay, and (3) functional outcome after 6 months of follow-up. We conducted a separate analysis of the first 30 min and the remaining segments of prospective cEEG recordings according to the ACNS Standardized Critical Care EEG Terminology as well as NCS criteria and review of clinical data of 32 neurological critical care patients. In 17 patients with epileptiform discharges within the first 30 min of EEG (group 1), electrographic seizures were observed in 23.5% (n = 4), rhythmic or periodic EEG patterns of 'ictal-interictal uncertainty' in 64.7% (n = 11), and neither electrographic seizures nor RPPIIU in 11.8% (n = 2). In 15 patients with no epileptiform discharges in the first 30 min of EEG (group 2), no electrographic seizures were recorded on subsequent cEEG, RPPIIU were seen in 26.7% (n = 4), and neither electrographic seizures nor RPPIIU in 73.3% (n = 11). The incidence of EEG patterns on cEEG was significantly different between the two groups (p = 0.008). Patients with early epileptiform discharges developed acute seizures more frequently than patients without early epileptiform discharges (p = 0.009). Finally, functional outcome six months after discharge was significantly worse in patients with early epileptiform discharges (p=0.01). Epileptiform discharges within the first 30 min of EEG recording are predictive for the occurrence of ictal EEG patterns and for RPPIIU on subsequent cEEG, for acute convulsive seizures during the ICU stay, and for a worse functional outcome after 6 months of follow-up. This article is part of a Special Issue entitled Status Epilepticus. Copyright © 2015 Elsevier Inc. All rights reserved.

Central nervous system hyperexcitability associated with glutamate dehydrogenase gain of function mutations.

PubMed

Raizen, David M; Brooks-Kayal, Amy; Steinkrauss, Linda; Tennekoon, Gihan I; Stanley, Charles A; Kelly, Andrea

2005-03-01

To describe seizure phenotypes associated with the hyperinsulinism/hyperammonemia syndrome (HI/HA), which is caused by gain of function mutations in the enzyme glutamate dehydrogenase (GDH). A retrospective review of records of 14 patients with HI/HA. Nine patients had seizures as the first symptom of HI/HA, and six had seizures in the absence of hypoglycemia. No electroencephalogram (EEG) background abnormalities were identified. In four patients, EEG recordings during seizures in the setting of normal blood glucose contained generalized epileptiform discharges. EEGs of three of these patients showed 0.5- to 2-second generalized irregular spike-and-wave discharge at 3 to 6 Hz corresponding to eye blinks, eye rolling, or staring. The EEG of the fourth patient consisted of 20 seconds of generalized regular spike-and-wave discharge at 3 Hz in the clinical context of staring and unresponsiveness. In two patients, seizure control worsened with carbamezapine or oxcarbezapine treatment. In patients with HI/HA, generalized seizures are common and can occur in the absence of hypoglycemia. The drugs carbamazepine and oxcarbazepine should be used with caution for treatment. Pathogenesis of epilepsy in these patients may be related to effects of GDH mutations in the brain, perhaps in combination with effects of recurrent hypoglycemia and chronic hyperammonemia.

An automated sleep-state classification algorithm for quantifying sleep timing and sleep-dependent dynamics of electroencephalographic and cerebral metabolic parameters

PubMed Central

Rempe, Michael J; Clegern, William C; Wisor, Jonathan P

2015-01-01

Introduction Rodent sleep research uses electroencephalography (EEG) and electromyography (EMG) to determine the sleep state of an animal at any given time. EEG and EMG signals, typically sampled at >100 Hz, are segmented arbitrarily into epochs of equal duration (usually 2–10 seconds), and each epoch is scored as wake, slow-wave sleep (SWS), or rapid-eye-movement sleep (REMS), on the basis of visual inspection. Automated state scoring can minimize the burden associated with state and thereby facilitate the use of shorter epoch durations. Methods We developed a semiautomated state-scoring procedure that uses a combination of principal component analysis and naïve Bayes classification, with the EEG and EMG as inputs. We validated this algorithm against human-scored sleep-state scoring of data from C57BL/6J and BALB/CJ mice. We then applied a general homeostatic model to characterize the state-dependent dynamics of sleep slow-wave activity and cerebral glycolytic flux, measured as lactate concentration. Results More than 89% of epochs scored as wake or SWS by the human were scored as the same state by the machine, whether scoring in 2-second or 10-second epochs. The majority of epochs scored as REMS by the human were also scored as REMS by the machine. However, of epochs scored as REMS by the human, more than 10% were scored as SWS by the machine and 18 (10-second epochs) to 28% (2-second epochs) were scored as wake. These biases were not strain-specific, as strain differences in sleep-state timing relative to the light/dark cycle, EEG power spectral profiles, and the homeostatic dynamics of both slow waves and lactate were detected equally effectively with the automated method or the manual scoring method. Error associated with mathematical modeling of temporal dynamics of both EEG slow-wave activity and cerebral lactate either did not differ significantly when state scoring was done with automated versus visual scoring, or was reduced with automated state scoring relative to manual classification. Conclusions Machine scoring is as effective as human scoring in detecting experimental effects in rodent sleep studies. Automated scoring is an efficient alternative to visual inspection in studies of strain differences in sleep and the temporal dynamics of sleep-related physiological parameters. PMID:26366107

Real time algorithms for sharp wave ripple detection.

PubMed

Sethi, Ankit; Kemere, Caleb

2014-01-01

Neural activity during sharp wave ripples (SWR), short bursts of co-ordinated oscillatory activity in the CA1 region of the rodent hippocampus, is implicated in a variety of memory functions from consolidation to recall. Detection of these events in an algorithmic framework, has thus far relied on simple thresholding techniques with heuristically derived parameters. This study is an investigation into testing and improving the current methods for detection of SWR events in neural recordings. We propose and profile methods to reduce latency in ripple detection. Proposed algorithms are tested on simulated ripple data. The findings show that simple realtime algorithms can improve upon existing power thresholding methods and can detect ripple activity with latencies in the range of 10-20 ms.

Symposium on Turbulent Shear Flows (3rd), University of California, Davis, California, 9-11 September 1981.

DTIC Science & Technology

1981-09-01

1970, p. 417. 16 Wieghardt, K., Tillmann, W., "On the Turbulent Friction Layer for Rising Pressure", NACA, TM 1374, 1957. 17 Andersen, P.S., Kays, W.M...thickness is 5000. derived from the "Strong Reynolds Analogy" (S.R.A.) A 12 eeg . deflection of the wall around a sharp edge may be us d o ep es nt p~-- o Tu...which yields (3) / / 02 /S - t 02 S = Se-t boundayI y,0in flame I with so as the initial shear layer thickness. zonemod 2S 10 / tms 2. Initial

Changes in sleep quality of athletes under normobaric hypoxia equivalent to 2,000-m altitude: a polysomnographic study.

PubMed

Hoshikawa, Masako; Uchida, Sunao; Sugo, Takayuki; Kumai, Yasuko; Hanai, Yoshiteru; Kawahara, Takashi

2007-12-01

This study evaluated the sleep quality of athletes in normobaric hypoxia at a simulated altitude of 2,000 m. Eight male athletes slept in normoxic condition (NC) and hypoxic conditions equivalent to those at 2,000-m altitude (HC). Polysomnographic recordings of sleep included the electroencephalogram (EEG), electrooculogram, chin surface electromyogram, and electrocardiogram. Thoracic and abdominal motion, nasal and oral airflow, and arterial blood oxygen saturation (Sa(O(2))) were also recorded. Standard visual sleep stage scoring and fast Fourier transformation analyses of the EEG were performed on 30-s epochs. Subjective sleepiness and urinary catecholamines were also monitored. Mean Sa(O(2)) decreased and respiratory disturbances increased with HC. The increase in respiratory disturbances was significant, but the increase was small and subclinical. The duration of slow-wave sleep (stage 3 and 4) and total delta power (<3 Hz) of the all-night non-rapid eye movement sleep EEG decreased for HC compared with NC. Subjective sleepiness and amounts of urinary catecholamines did not differ between the conditions. These results indicate that acute exposure to normobaric hypoxia equivalent to that at 2,000-m altitude decreased slow-wave sleep in athletes, but it did not change subjective sleepiness or amounts of urinary catecholamines.

Apparatus and method for epileptic seizure detection using non-linear techniques

DOEpatents

Hively, L.M.; Clapp, N.E.; Daw, C.S.; Lawkins, W.F.

1998-04-28

Methods and apparatus are disclosed for automatically detecting epileptic seizures by monitoring and analyzing brain wave (EEG or MEG) signals. Steps include: acquiring the brain wave data from the patient; digitizing the data; obtaining nonlinear measures of the data via chaotic time series analysis; obtaining time serial trends in the nonlinear measures; determining that one or more trends in the nonlinear measures indicate a seizure, and providing notification of seizure occurrence. 76 figs.

Scale-Free Music of the Brain

PubMed Central

Wu, Dan; Li, Chao-Yi; Yao, De-Zhong

2009-01-01

Background There is growing interest in the relation between the brain and music. The appealing similarity between brainwaves and the rhythms of music has motivated many scientists to seek a connection between them. A variety of transferring rules has been utilized to convert the brainwaves into music; and most of them are mainly based on spectra feature of EEG. Methodology/Principal Findings In this study, audibly recognizable scale-free music was deduced from individual Electroencephalogram (EEG) waveforms. The translation rules include the direct mapping from the period of an EEG waveform to the duration of a note, the logarithmic mapping of the change of average power of EEG to music intensity according to the Fechner's law, and a scale-free based mapping from the amplitude of EEG to music pitch according to the power law. To show the actual effect, we applied the deduced sonification rules to EEG segments recorded during rapid-eye movement sleep (REM) and slow-wave sleep (SWS). The resulting music is vivid and different between the two mental states; the melody during REM sleep sounds fast and lively, whereas that in SWS sleep is slow and tranquil. 60 volunteers evaluated 25 music pieces, 10 from REM, 10 from SWS and 5 from white noise (WN), 74.3% experienced a happy emotion from REM and felt boring and drowsy when listening to SWS, and the average accuracy for all the music pieces identification is 86.8%(κ = 0.800, P<0.001). We also applied the method to the EEG data from eyes closed, eyes open and epileptic EEG, and the results showed these mental states can be identified by listeners. Conclusions/Significance The sonification rules may identify the mental states of the brain, which provide a real-time strategy for monitoring brain activities and are potentially useful to neurofeedback therapy. PMID:19526057

Automatic reference selection for quantitative EEG interpretation: identification of diffuse/localised activity and the active earlobe reference, iterative detection of the distribution of EEG rhythms.

PubMed

Wang, Bei; Wang, Xingyu; Ikeda, Akio; Nagamine, Takashi; Shibasaki, Hiroshi; Nakamura, Masatoshi

2014-01-01

EEG (Electroencephalograph) interpretation is important for the diagnosis of neurological disorders. The proper adjustment of the montage can highlight the EEG rhythm of interest and avoid false interpretation. The aim of this study was to develop an automatic reference selection method to identify a suitable reference. The results may contribute to the accurate inspection of the distribution of EEG rhythms for quantitative EEG interpretation. The method includes two pre-judgements and one iterative detection module. The diffuse case is initially identified by pre-judgement 1 when intermittent rhythmic waveforms occur over large areas along the scalp. The earlobe reference or averaged reference is adopted for the diffuse case due to the effect of the earlobe reference depending on pre-judgement 2. An iterative detection algorithm is developed for the localised case when the signal is distributed in a small area of the brain. The suitable averaged reference is finally determined based on the detected focal and distributed electrodes. The presented technique was applied to the pathological EEG recordings of nine patients. One example of the diffuse case is introduced by illustrating the results of the pre-judgements. The diffusely intermittent rhythmic slow wave is identified. The effect of active earlobe reference is analysed. Two examples of the localised case are presented, indicating the results of the iterative detection module. The focal and distributed electrodes are detected automatically during the repeating algorithm. The identification of diffuse and localised activity was satisfactory compared with the visual inspection. The EEG rhythm of interest can be highlighted using a suitable selected reference. The implementation of an automatic reference selection method is helpful to detect the distribution of an EEG rhythm, which can improve the accuracy of EEG interpretation during both visual inspection and automatic interpretation. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Surface wave scattering from sharp lateral discontinuities

NASA Astrophysics Data System (ADS)

Pollitz, Fred F.

1994-11-01

The problem of surface wave scattering is re-explored, with quasi-degenerate normal mode coupling as the starting point. For coupling among specified spheroidal and toroidal mode dispersion branches, a set of coupled wave equations is derived in the frequency domain for first-arriving Rayleigh and Love waves. The solutions to these coupled wave equations using linear perturbation theory are surface integrals over the unit sphere covering the lateral distribution of perturbations in Earth structure. For isotropic structural perturbations and surface topographic perturbations, these solutions agree with the Born scattering theory previously obtained by Snieder and Romanowicz. By transforming these surface integrals into line integrals along the boundaries of the heterogeneous regions in the case of sharp discontinuities, and by using uniformly valid Green's functions, it is possible to extend the solution to the case of multiple scattering interactions. The proposed method allows the relatively rapid calculation of exact second order scattered wavefield potentials for scattering by sharp discontinuities, and it has many advantages not realized in earlier treatments. It employs a spherical Earth geometry, uses no far field approximation, and implicitly contains backward as well as forward scattering. Comparisons of asymptotic scattering and an exact solution with single scattering and multiple scattering integral formulations show that the phase perturbation predicted by geometrical optics breaks down for scatterers less than about six wavelengths in diameter, and second-order scattering predicts well both the amplitude and phase pattern of the exact wavefield for sufficiently small scatterers, less than about three wavelengths in diameter for anomalies of a few percent.

Retinoic Acid Signaling Affects Cortical Synchrony During Sleep

NASA Astrophysics Data System (ADS)

Maret, Stéphanie; Franken, Paul; Dauvilliers, Yves; Ghyselinck, Norbert B.; Chambon, Pierre; Tafti, Mehdi

2005-10-01

Delta oscillations, characteristic of the electroencephalogram (EEG) of slow wave sleep, estimate sleep depth and need and are thought to be closely linked to the recovery function of sleep. The cellular mechanisms underlying the generation of delta waves at the cortical and thalamic levels are well documented, but the molecular regulatory mechanisms remain elusive. Here we demonstrate in the mouse that the gene encoding the retinoic acid receptor beta determines the contribution of delta oscillations to the sleep EEG. Thus, retinoic acid signaling, which is involved in the patterning of the brain and dopaminergic pathways, regulates cortical synchrony in the adult.

Early and Later Life Stress Alter Brain Activity and Sleep in Rats

PubMed Central

Mrdalj, Jelena; Pallesen, Ståle; Milde, Anne Marita; Jellestad, Finn Konow; Murison, Robert; Ursin, Reidun; Bjorvatn, Bjørn; Grønli, Janne

2013-01-01

Exposure to early life stress may profoundly influence the developing brain in lasting ways. Neuropsychiatric disorders associated with early life adversity may involve neural changes reflected in EEG power as a measure of brain activity and disturbed sleep. The main aim of the present study was for the first time to characterize possible changes in adult EEG power after postnatal maternal separation in rats. Furthermore, in the same animals, we investigated how EEG power and sleep architecture were affected after exposure to a chronic mild stress protocol. During postnatal day 2–14 male rats were exposed to either long maternal separation (180 min) or brief maternal separation (10 min). Long maternally separated offspring showed a sleep-wake nonspecific reduction in adult EEG power at the frontal EEG derivation compared to the brief maternally separated group. The quality of slow wave sleep differed as the long maternally separated group showed lower delta power in the frontal-frontal EEG and a slower reduction of the sleep pressure. Exposure to chronic mild stress led to a lower EEG power in both groups. Chronic exposure to mild stressors affected sleep differently in the two groups of maternal separation. Long maternally separated offspring showed more total sleep time, more episodes of rapid eye movement sleep and higher percentage of non-rapid eye movement episodes ending in rapid eye movement sleep compared to brief maternal separation. Chronic stress affected similarly other sleep parameters and flattened the sleep homeostasis curves in all offspring. The results confirm that early environmental conditions modulate the brain functioning in a long-lasting way. PMID:23922857

Effects of Marijuana on Ictal and Interictal EEG Activities in Idiopathic Generalized Epilepsy.

PubMed

Sivakumar, Sanjeev; Zutshi, Deepti; Seraji-Bozorgzad, Navid; Shah, Aashit K

2017-01-01

Marijuana-based treatment for refractory epilepsy shows promise in surveys, case series, and clinical trials. However, literature on their EEG effects is sparse. Our objective is to analyze the effect of marijuana on EEG in a 24-year-old patient with idiopathic generalized epilepsy treated with cannabis. We blindly reviewed 3 long-term EEGs-a 24-hour study while only on antiepileptic drugs, a 72-hour EEG with Cannabis indica smoked on days 1 and 3 in addition to antiepileptic drugs, and a 48-hour EEG with combination C indica/sativa smoked on day 1 plus antiepileptic drugs. Generalized spike-wave discharges and diffuse paroxysmal fast activity were categorized as interictal and ictal, based on duration of less than 10 seconds or greater, respectively. Data from three studies concatenated into contiguous time series, with usage of marijuana modeled as time-dependent discrete variable while interictal and ictal events constituted dependent variables. Analysis of variance as initial test for significance followed by time series analysis using Generalized Autoregressive Conditional Heteroscedasticity model was performed. Statistical significance for lower interictal events (analysis of variance P = 0.001) was seen during C indica use, but not for C indica/sativa mixture (P = 0.629) or ictal events (P = 0.087). However, time series analysis revealed a significant inverse correlation between marijuana use, with interictal (P < 0.0004) and ictal (P = 0.002) event rates. Using a novel approach to EEG data, we demonstrate a decrease in interictal and ictal electrographic events during marijuana use. Larger samples of patients and EEG, with standardized cannabinoid formulation and dosing, are needed to validate our findings.

Analyze the dynamic features of rat EEG using wavelet entropy.

PubMed

Feng, Zhouyan; Chen, Hang

2005-01-01

Wavelet entropy (WE), a new method of complexity measure for non-stationary signals, was used to investigate the dynamic features of rat EEGs under three vigilance states. The EEGs of the freely moving rats were recorded with implanted electrodes and were decomposed into four components of delta, theta, alpha and beta by using multi-resolution wavelet transform. Then, the wavelet entropy curves were calculated as a function of time. The results showed that there were significant differences among the average WEs of EEGs recorded under the vigilance states of waking, slow wave sleep (SWS) and rapid eye movement (REM) sleep. The changes of WE had different relationships with the four power components under different states. Moreover, there was evident rhythm in EEG WEs of SWS sleep for most experimental rats, which indicated a reciprocal relationship between slow waves and sleep spindles in the micro-states of SWS sleep. Therefore, WE can be used not only to distinguish the long-term changes in EEG complexity, but also to reveal the short-term changes in EEG micro-state.

Phase transition of traveling waves in bacterial colony pattern

NASA Astrophysics Data System (ADS)

Wakano, Joe Yuichiro; Komoto, Atsushi; Yamaguchi, Yukio

2004-05-01

Depending on the growth condition, bacterial colonies can exhibit different morphologies. Many previous studies have used reaction diffusion equations to reproduce spatial patterns. They have revealed that nonlinear reaction term can produce diverse patterns as well as nonlinear diffusion coefficient. Typical reaction term consists of nutrient consumption, bacterial reproduction, and sporulation. Among them, the functional form of sporulation rate has not been biologically investigated. Here we report experimentally measured sporulation rate. Then, based on the result, a reaction diffusion model is proposed. One-dimensional simulation showed the existence of traveling wave solution. We study the wave form as a function of the initial nutrient concentration and find two distinct types of solution. Moreover, transition between them is very sharp, which is analogous to phase transition. The velocity of traveling wave also shows sharp transition in nonlinear diffusion model, which is consistent with the previous experimental result. The phenomenon can be explained by separatrix in reaction term dynamics. Results of two-dimensional simulation are also shown and discussed.

Seizure-onset patterns in focal cortical dysplasia and neurodevelopmental tumors: Relationship with surgical prognosis and neuropathologic subtypes.

PubMed

Lagarde, Stanislas; Bonini, Francesca; McGonigal, Aileen; Chauvel, Patrick; Gavaret, Martine; Scavarda, Didier; Carron, Romain; Régis, Jean; Aubert, Sandrine; Villeneuve, Nathalie; Giusiano, Bernard; Figarella-Branger, Dominique; Trebuchon, Agnès; Bartolomei, Fabrice

2016-09-01

The study of intracerebral electroencephalography (EEG) seizure-onset patterns is crucial to accurately define the epileptogenic zone and guide successful surgical resection. It also raises important pathophysiologic issues concerning mechanisms of seizure generation. Until now, several seizure-onset patterns have been described using distinct recording methods (subdural, depth electrode), mostly in temporal lobe epilepsies or with heterogeneous neocortical lesions. We analyzed data from a cohort of 53 consecutive patients explored by stereoelectroencephalography (SEEG) and with pathologically confirmed malformation of cortical development (MCD; including focal cortical dysplasia [FCD] and neurodevelopmental tumors [NDTs]). We identified six seizure-onset patterns using visual and time-frequency analysis: low-voltage fast activity (LVFA); preictal spiking followed by LVFA; burst of polyspikes followed by LVFA; slow wave/DC shift followed by LVFA; theta/alpha sharp waves; and rhythmic spikes/spike-waves. We found a high prevalence of patterns that included LVFA (83%), indicating nevertheless that LVFA is not a constant characteristic of seizure onset. An association between seizure-onset patterns and histologic types was found (p = 001). The more prevalent patterns were as follows: (1) in FCD type I LVFA (23.1%) and slow wave/baseline shift followed by LVFA (15.4%); (2) in FCD type II burst of polyspikes followed by LVFA (31%), LVFA (27.6%), and preictal spiking followed by LVFA (27.6%); (3) in NDT, LVFA (54.5%). We found that a seizure-onset pattern that included LVFA was associated with favorable postsurgical outcome, but the completeness of the EZ resection was the sole independent predictive variable. Six different seizure-onset patterns can be described in FCD and NDT. Better postsurgical outcome is associated with patterns that incorporate LVFA. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

Analyzing large data sets acquired through telemetry from rats exposed to organophosphorous compounds: an EEG study.

PubMed

de Araujo Furtado, Marcio; Zheng, Andy; Sedigh-Sarvestani, Madineh; Lumley, Lucille; Lichtenstein, Spencer; Yourick, Debra

2009-10-30

The organophosphorous compound soman is an acetylcholinesterase inhibitor that causes damage to the brain. Exposure to soman causes neuropathology as a result of prolonged and recurrent seizures. In the present study, long-term recordings of cortical EEG were used to develop an unbiased means to quantify measures of seizure activity in a large data set while excluding other signal types. Rats were implanted with telemetry transmitters and exposed to soman followed by treatment with therapeutics similar to those administered in the field after nerve agent exposure. EEG, activity and temperature were recorded continuously for a minimum of 2 days pre-exposure and 15 days post-exposure. A set of automatic MATLAB algorithms have been developed to remove artifacts and measure the characteristics of long-term EEG recordings. The algorithms use short-time Fourier transforms to compute the power spectrum of the signal for 2-s intervals. The spectrum is then divided into the delta, theta, alpha, and beta frequency bands. A linear fit to the power spectrum is used to distinguish normal EEG activity from artifacts and high amplitude spike wave activity. Changes in time spent in seizure over a prolonged period are a powerful indicator of the effects of novel therapeutics against seizures. A graphical user interface has been created that simultaneously plots the raw EEG in the time domain, the power spectrum, and the wavelet transform. Motor activity and temperature are associated with EEG changes. The accuracy of this algorithm is also verified against visual inspection of video recordings up to 3 days after exposure.

Adenosine deaminase polymorphism affects sleep EEG spectral power in a large epidemiological sample.

PubMed

Mazzotti, Diego Robles; Guindalini, Camila; de Souza, Altay Alves Lino; Sato, João Ricardo; Santos-Silva, Rogério; Bittencourt, Lia Rita Azeredo; Tufik, Sergio

2012-01-01

Slow wave oscillations in the electroencephalogram (EEG) during sleep may reflect both sleep need and intensity, which are implied in homeostatic regulation. Adenosine is strongly implicated in sleep homeostasis, and a single nucleotide polymorphism in the adenosine deaminase gene (ADA G22A) has been associated with deeper and more efficient sleep. The present study verified the association between the ADA G22A polymorphism and changes in sleep EEG spectral power (from C3-A2, C4-A1, O1-A2, and O2-A1 derivations) in the Epidemiologic Sleep Study (EPISONO) sample from São Paulo, Brazil. Eight-hundred individuals were subjected to full-night polysomnography and ADA G22A genotyping. Spectral analysis of the EEG was carried out in all individuals using fast Fourier transformation of the signals from each EEG electrode. The genotype groups were compared in the whole sample and in a subsample of 120 individuals matched according to ADA genotype for age, gender, body mass index, caffeine intake status, presence of sleep disturbance, and sleep-disturbing medication. When compared with homozygous GG genotype carriers, A allele carriers showed higher delta spectral power in Stage 1 and Stages 3+4 of sleep, and increased theta spectral power in Stages 1, 2 and REM sleep. These changes were seen both in the whole sample and in the matched subset. The higher EEG spectral power indicates that the sleep of individuals carrying the A allele may be more intense. Therefore, this polymorphism may be an important source of variation in sleep homeostasis in humans, through modulation of specific components of the sleep EEG.

Déjà vu phenomenon-related EEG pattern. Case report.

PubMed

Vlasov, P N; Chervyakov, A V; Gnezditskii, V V

2013-01-01

Déjà vu (DV, from French déjà vu - "already seen") is an aberration of psychic activity associated with transitory erroneous perception of novel circumstances, objects, or people as already known. This study aimed to record the EEG pattern of déjà vu. The subjects participated in a survey concerning déjà vu characteristics and underwent ambulatory EEG monitoring (12-16 h). In patients with epilepsy, DV episodes began with polyspike activity in the right temporal lobe region and, in some cases, ended with slow-wave theta-delta activity over the right hemisphere. There were no epileptic discharges in healthy respondents during DV. Two types of déjà vu are suggested to exist: "pathological-epileptic" déjà vu, characteristic of patients with epilepsy and equivalent to an epileptic seizure, and "nonpathological-nonepileptic" déjà vu, which is characteristic of healthy people and psychological phenomenon.

A Removal of Eye Movement and Blink Artifacts from EEG Data Using Morphological Component Analysis

PubMed Central

Wagatsuma, Hiroaki

2017-01-01

EEG signals contain a large amount of ocular artifacts with different time-frequency properties mixing together in EEGs of interest. The artifact removal has been substantially dealt with by existing decomposition methods known as PCA and ICA based on the orthogonality of signal vectors or statistical independence of signal components. We focused on the signal morphology and proposed a systematic decomposition method to identify the type of signal components on the basis of sparsity in the time-frequency domain based on Morphological Component Analysis (MCA), which provides a way of reconstruction that guarantees accuracy in reconstruction by using multiple bases in accordance with the concept of “dictionary.” MCA was applied to decompose the real EEG signal and clarified the best combination of dictionaries for this purpose. In our proposed semirealistic biological signal analysis with iEEGs recorded from the brain intracranially, those signals were successfully decomposed into original types by a linear expansion of waveforms, such as redundant transforms: UDWT, DCT, LDCT, DST, and DIRAC. Our result demonstrated that the most suitable combination for EEG data analysis was UDWT, DST, and DIRAC to represent the baseline envelope, multifrequency wave-forms, and spiking activities individually as representative types of EEG morphologies. PMID:28194221

Transient Effect of the Noise of Passing Trucks on Sleep Eeg

NASA Astrophysics Data System (ADS)

Suzuki, S.; Kawada, T.; Kiryu, Y.; Sasazawa, Y.; Tamura, Y.

1997-08-01

Twelve subjects were exposed to the noise of passing trucks at peak levels of 45, 50, 55 and 60 dB(A) for 15 min intervals throughout the night each for seven to 12 nights. Effects of the noise were observed by sleep electroencephalography (EEG). Three EEG parameters were affected by the noise event during stage 2. The number of spindles per epoch was depressed on average from 1·78 to 1·02 spindles per epoch or to 57% by the noise event of 60 dB(A), which lasted for only one minute. The threshold level for inducing the decrease was 32 dB(A), as assessed by a regression equation. Time % delta wave was depressed for six minutes, with a threshold level of 41 dB(A). The integral EMG increased in response to the noise event for one minute, and the threshold level for the integral EMG was 34 dB(A).

Unifying decoherence and the Heisenberg Principle

NASA Astrophysics Data System (ADS)

Janssens, Bas

2017-08-01

We exhibit three inequalities involving quantum measurement, all of which are sharp and state independent. The first inequality bounds the performance of joint measurement. The second quantifies the trade-off between the measurement quality and the disturbance caused on the measured system. Finally, the third inequality provides a sharp lower bound on the amount of decoherence in terms of the measurement quality. This gives a unified description of both the Heisenberg uncertainty principle and the collapse of the wave function.

Detection of Drug Effects on Brain Activity using EEG-P300 with Similar Stimuli

NASA Astrophysics Data System (ADS)

Turnip, Arjon; Dwi Esti, K.; Faizal Amri, M.; Simbolon, Artha I.; Agung Suhendra, M.; IsKandar, Shelly; Wirakusumah, Firman F.

2017-07-01

Drug addiction poses a serious problem to our species. The worry that our significant family might be involved in drug use and are concerned to know how to detect drug use. Examinations of thirty taped EEG recordings were performed. The subjects consist of three group: addictive, methadone treatment (rehabilitation), and control (normal) which 10 subjects for each group. Statistical analysis was performed for the relative frequency of wave bands. The higher average amplitude is obtained from the addiction subjects. In the comparison with the signals source, channels P3 provide slightly higher average amplitude than other channels for all of subjects.

Wide band cryogenic ultra-high vacuum microwave absorber

DOEpatents

Campisi, Isidoro E.

1992-01-01

An absorber wave guide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the wave guide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the wave guide.

The energy balance of wind waves and the remote sensing problem

NASA Technical Reports Server (NTRS)

Hasselmann, K.

1972-01-01

Measurements of wave growth indicate an energy balance of the wave spectrum governed primarily by input from the atmosphere, nonlinear transfer to shorter and longer waves, and advection. The pronounced spectral peak and sharp low frequency cut-off characteristic of fetch-limited spectra are explained as a self-stabilizing feature of the nonlinear wave-wave interactions. The momentum transferred from the atmosphere to the wind waves accounts for a large part of the wind drag. These findings are relevant for remote microwave sensing of the sea surface by backscatter and passive radiometry methods.

Microsensors and wireless system for monitoring epilepsy

NASA Astrophysics Data System (ADS)

Whitchurch, Ashwin K.; Ashok, B. H.; Kumaar, Raman V.; Sarukesi, K.; Jose, K. A.; Varadan, Vijay K.

2003-07-01

Epilepsy is a form of brain disorder caused by abnormal discharges of neurons. The most common manifestations of epilepsy are seizures which could affect visual, aural and motor abilities of a person. Absence epilepsy is a form of epilepsy common mostly in children. The most common manifestations of absence epilepsy are staring and transient loss of responsiveness. Also, subtle motor activities may occur. Due to the subtle nature of these symptoms, episodes of absence epilepsy may often go unrecognized for long periods of time or be mistakenly attributed to attention deficit disorder or daydreaming. Spells of absence epilepsy may last about 10 seconds and occur hundreds of times each day. Patients have no recollections of the events occurred during those seizures and will resume normal activity without any postictal symptoms. The EEG during such episodes of Absence epilepsy shows intermittent activity of 3 Hz generalized spike and wave complexes. As EEG is the only way of detecting such symptoms, it is required to monitor the EEG of the patient for a long time, usually the whole day. This requires that the patient be connected to the EEG recorder all the time and thus remain only in the bed. So, effectively the EEG is being monitored only when the patient is stationary. The wireless monitoring system described in this paper aims at eliminating this constraint and enables the physician to monitor the EEG when the patient resumes his normal activities. This approach could even help the doctor identify possible triggers of absence epilepsy.

Guiding, bending, and splitting of coupled defect surface modes in a surface-wave photonic crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Zhen; Gao, Fei; Zhang, Baile, E-mail: blzhang@ntu.edu.sg

2016-01-25

We experimentally demonstrate a type of waveguiding mechanism for coupled surface-wave defect modes in a surface-wave photonic crystal. Unlike conventional spoof surface plasmon waveguides, waveguiding of coupled surface-wave defect modes is achieved through weak coupling between tightly localized defect cavities in an otherwise gapped surface-wave photonic crystal, as a classical wave analogue of tight-binding electronic wavefunctions in solid state lattices. Wave patterns associated with the high transmission of coupled defect surface modes are directly mapped with a near-field microwave scanning probe for various structures including a straight waveguide, a sharp corner, and a T-shaped splitter. These results may find usemore » in the design of integrated surface-wave devices with suppressed crosstalk.« less

Electroencephalographic Variation during End Maintenance and Emergence from Surgical Anesthesia

PubMed Central

MacColl, Jono N.; Illing, Sam; Sleigh, Jamie W.

2014-01-01

The re-establishment of conscious awareness after discontinuing general anesthesia has often been assumed to be the inverse of loss of consciousness. This is despite the obvious asymmetry in the initiation and termination of natural sleep. In order to characterize the restoration of consciousness after surgery, we recorded frontal electroencephalograph (EEG) from 100 patients in the operating room during maintenance and emergence from general anesthesia. We have defined, for the first time, 4 steady-state patterns of anesthetic maintenance based on the relative EEG power in the slow-wave (<14 Hz) frequency bands that dominate sleep and anesthesia. Unlike single-drug experiments performed in healthy volunteers, we found that surgical patients exhibited greater electroencephalographic heterogeneity while re-establishing conscious awareness after drug discontinuation. Moreover, these emergence patterns could be broadly grouped according to the duration and rapidity of transitions amongst these slow-wave dominated brain states that precede awakening. Most patients progressed gradually from a pattern characterized by strong peaks of delta (0.5–4 Hz) and alpha/spindle (8–14 Hz) power (‘Slow-Wave Anesthesia’) to a state marked by low delta-spindle power (‘Non Slow-Wave Anesthesia’) before awakening. However, 31% of patients transitioned abruptly from Slow-Wave Anesthesia to waking; they were also more likely to express pain in the post-operative period. Our results, based on sleep-staging classification, provide the first systematized nomenclature for tracking brain states under general anesthesia from maintenance to emergence, and suggest that these transitions may correlate with post-operative outcomes such as pain. PMID:25264892

Effects of GF-015535-00, a novel α1 GABA A receptor ligand, on the sleep-wake cycle in mice, with reference to zolpidem.

PubMed

Anaclet, Christelle; Zhang, Mei; Zhao, Chunmei; Buda, Colette; Seugnet, Laurent; Lin, Jian-Sheng

2012-01-01

Novel, safe, and efficient hypnotic compounds capable of enhancing physiological sleep are still in great demand in the therapy of insomnia. This study compares the sleep-wake effects of a new α1 GABA(A) receptor subunit ligand, GF-015535-00, with those of zolpidem, the widely utilized hypnotic compound. Nine C57Bl6/J male mice were chronically implanted with electrodes for EEG and sleep-wake monitoring. Each mouse received 3 doses of GF-015535-00 and zolpidem. Time spent in sleep-wake states and cortical EEG power spectra were analyzed. Both zolpidem and GF-015535-00 prominently enhanced slow wave sleep and paradoxical sleep in the mouse. However, as compared with zolpidem, GF-015535-00 showed several important differences: (1) a comparable sleep-enhancing effect was obtained with a 10 fold smaller dose; (2) the induced sleep was less fragmented; (3) the risk of subsequent wake rebound was less prominent; and (4) the cortical EEG power ratio between slow wave sleep and wake was similar to that of natural sleep and thus compatible with physiological sleep. The characteristics of the sleep-wake effects of GF-015535-00 in mice could be potentially beneficial for its use as a therapeutic compound in the treatment of insomnia. Further investigations are required to assess whether the same characteristics are conserved in other animal models and humans.

EEG spectral power density profiles during NREM sleep for gaboxadol and zolpidem in patients with primary insomnia.

PubMed

Lundahl, Jonas; Deacon, Steve; Maurice, Damien; Staner, Luc

2012-08-01

There is significant interest in the functional significance and the therapeutic value of slow-wave sleep (SWS)-enhancing drugs. A prerequisite for studies of the functional differences is characterization of the electroencephalography (EEG) spectra following treatment in relevant patients. We evaluate for the first time gaboxadol and zolpidem treatments in insomniac patients using power spectra analysis. We carried out two randomized, double-blind, crossover studies. Study 1, 38 patients received gaboxadol 10 mg and 20 mg and zolpidem 10 mg; study 2, 23 patients received gaboxadol 5 mg and 15 mg. Treatments were administered during two nights and compared with placebo. Gaboxadol 10, 15 and 20 mg enhanced slow-wave activity (SWA) and theta power. In 1 Hz bins gaboxadol 10 and 20 mg enhanced power up to 9 Hz. In study 2, 15 mg gaboxadol showed a similar effect pattern. Zolpidem suppressed theta and alpha power, and increased sigma power, with no effect on SWA. In the 1 Hz bins zolpidem suppressed power between 5-10 Hz. Gaboxadol dose-dependently increased SWA and theta power in insomniac patients. In contrast, zolpidem did not affect SWA, reduced theta and alpha activity and enhanced sigma power. EEG spectral power differences may be consequences of the different mechanisms of action for zolpidem and the SWS-enhancing agent, gaboxadol.

[Extraction of evoked related potentials by using the combination of independent component analysis and wavelet analysis].

PubMed

Zou, Ling; Chen, Shuyue; Sun, Yuqiang; Ma, Zhenghua

2010-08-01

In this paper we present a new method of combining Independent Component Analysis (ICA) and Wavelet de-noising algorithm to extract Evoked Related Potentials (ERPs). First, the extended Infomax-ICA algorithm is used to analyze EEG signals and obtain the independent components (Ics); Then, the Wave Shrink (WS) method is applied to the demixed Ics as an intermediate step; the EEG data were rebuilt by using the inverse ICA based on the new Ics; the ERPs were extracted by using de-noised EEG data after being averaged several trials. The experimental results showed that the combined method and ICA method could remove eye artifacts and muscle artifacts mixed in the ERPs, while the combined method could retain the brain neural activity mixed in the noise Ics and could extract the weak ERPs efficiently from strong background artifacts.

An Experimental Study into the Scaling of an Unswept-Sharp-Fin-Generated Shock/Turbulent Boundary Layer Interaction.

DTIC Science & Technology

1983-01-01

Influence Scaling of 2D and 3D Shock/Turbulent ioundary Layer Interactions at Compression Corners." AIM Paper 81-334, January 1981. 5. Kubota, H...generating 3D shock wave/boundary layer interactions 2 Unswept sharp fin interaction and coordinate system 3 Cobra probe measurements of Peake (4) at Mach 4...were made by two Druck 50 PSI transducers, each in- stalled in a computer-controlled 48-port Model 48J4 Scani- valve and referenced to vacuum. A 250

Voluntary Sleep Loss in Rats

PubMed Central

Oonk, Marcella; Krueger, James M.; Davis, Christopher J.

2016-01-01

Study Objectives: Animal sleep deprivation (SDEP), in contrast to human SDEP, is involuntary and involves repeated exposure to aversive stimuli including the inability of the animal to control the waking stimulus. Therefore, we explored intracranial self-stimulation (ICSS), an operant behavior, as a method for voluntary SDEP in rodents. Methods: Male Sprague-Dawley rats were implanted with electroencephalography/electromyography (EEG/EMG) recording electrodes and a unilateral bipolar electrode into the lateral hypothalamus. Rats were allowed to self-stimulate, or underwent gentle handling-induced SDEP (GH-SDEP), during the first 6 h of the light phase, after which they were allowed to sleep. Other rats performed the 6 h ICSS and 1 w later were subjected to 6 h of noncontingent stimulation (NCS). During NCS the individual stimulation patterns recorded during ICSS were replayed. Results: After GH-SDEP, ICSS, or NCS, time in nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep increased. Further, in the 24 h after SDEP, rats recovered all of the REM sleep lost during SDEP, but only 75% to 80% of the NREM sleep lost, regardless of the SDEP method. The magnitude of EEG slow wave responses occurring during NREM sleep also increased after SDEP treatments. However, NREM sleep EEG slow wave activity (SWA) responses were attenuated following ICSS, compared to GH-SDEP and NCS. Conclusions: We conclude that ICSS and NCS can be used to sleep deprive rats. Changes in rebound NREM sleep EEG SWA occurring after ICSS, NCS, and GH-SDEP suggest that nonspecific effects of the SDEP procedure differentially affect recovery sleep phenotypes. Citation: Oonk M, Krueger JM, Davis CJ. Voluntary sleep loss in rats. SLEEP 2016;39(7):1467–1479. PMID:27166236

Age Is Associated with Reduced Sharp-Wave Ripple Frequency and Altered Patterns of Neuronal Variability.

PubMed

Wiegand, Jean-Paul L; Gray, Daniel T; Schimanski, Lesley A; Lipa, Peter; Barnes, C A; Cowen, Stephen L

2016-05-18

Spatial and episodic memory performance declines with age, and the neural basis for this decline is not well understood. Sharp-wave ripples are brief (∼70 ms) high-frequency oscillatory events generated in the hippocampus and are associated with the consolidation of spatial memories. Given the connection between ripple oscillations and memory consolidation, we investigated whether the structure of ripple oscillations and ripple-triggered patterns of single-unit activity are altered in aged rats. Local field and single-unit activity surrounding sharp-wave ripple events were examined in the CA1 region of the hippocampus of old (n = 5) and young (n = 6) F344 rats during periods of rest preceding and following performance on a place-dependent eyeblink-conditioning task. Neural responses in aged rats differed from responses in young rats in several ways. First, compared with young rats, the rate of ripple occurrence (ripple density) is reduced in aged rats during postbehavior rest. Second, mean ripple frequency during prebehavior and postbehavior rest is lower in aged animals (aged: 132 Hz; young: 146 Hz). Third, single neurons in aged animals responded more consistently from ripple to ripple. Fourth, variability in interspike intervals was greater in aged rats. Finally, neurons were tuned to a narrower range of phases of the ripple oscillation relative to young animals. Together, these results suggest that the CA1 network in aged animals has a reduced "vocabulary" of available representational states. The hippocampus is a structure that is critical for the formation of episodic memories. Sharp-wave ripple events generated in the hippocampus have been implicated in memory consolidation processes critical to memory stabilization. We examine here whether these ripple oscillations are altered over the course of the life span, which could contribute to hippocampus-dependent memory deficits that occur during aging. This experiment used young and aged memory-impaired rats to examine age-related changes in ripple architecture, ripple-triggered spike variance, and spike-phase coherence. We found that there are, indeed, significant changes in characteristics of ripples in older animals that could impact consolidation processes and memory stabilization in the aged brain. Copyright © 2016 the authors 0270-6474/16/365650-11$15.00/0.

Age Is Associated with Reduced Sharp-Wave Ripple Frequency and Altered Patterns of Neuronal Variability

PubMed Central

Wiegand, Jean-Paul L.; Gray, Daniel T.; Schimanski, Lesley A.; Lipa, Peter; Barnes, C. A.

2016-01-01

Spatial and episodic memory performance declines with age, and the neural basis for this decline is not well understood. Sharp-wave ripples are brief (∼70 ms) high-frequency oscillatory events generated in the hippocampus and are associated with the consolidation of spatial memories. Given the connection between ripple oscillations and memory consolidation, we investigated whether the structure of ripple oscillations and ripple-triggered patterns of single-unit activity are altered in aged rats. Local field and single-unit activity surrounding sharp-wave ripple events were examined in the CA1 region of the hippocampus of old (n = 5) and young (n = 6) F344 rats during periods of rest preceding and following performance on a place-dependent eyeblink-conditioning task. Neural responses in aged rats differed from responses in young rats in several ways. First, compared with young rats, the rate of ripple occurrence (ripple density) is reduced in aged rats during postbehavior rest. Second, mean ripple frequency during prebehavior and postbehavior rest is lower in aged animals (aged: 132 Hz; young: 146 Hz). Third, single neurons in aged animals responded more consistently from ripple to ripple. Fourth, variability in interspike intervals was greater in aged rats. Finally, neurons were tuned to a narrower range of phases of the ripple oscillation relative to young animals. Together, these results suggest that the CA1 network in aged animals has a reduced “vocabulary” of available representational states. SIGNIFICANCE STATEMENT The hippocampus is a structure that is critical for the formation of episodic memories. Sharp-wave ripple events generated in the hippocampus have been implicated in memory consolidation processes critical to memory stabilization. We examine here whether these ripple oscillations are altered over the course of the life span, which could contribute to hippocampus-dependent memory deficits that occur during aging. This experiment used young and aged memory-impaired rats to examine age-related changes in ripple architecture, ripple-triggered spike variance, and spike-phase coherence. We found that there are, indeed, significant changes in characteristics of ripples in older animals that could impact consolidation processes and memory stabilization in the aged brain. PMID:27194342

Clinical and genetic features of human prion diseases in Catalonia: 1993-2002.

PubMed

Sanchez-Valle, R; Nos, C; Yagüe, J; Graus, F; Domínguez, A; Saiz, A

2004-10-01

We describe the clinical and genetic characteristics of the 85 definite or probable human prion diseases cases died between January 1993 and December 2002 in Catalonia (an autonomous community of Spain, 6 million population). Seventy-three (86%) cases were sporadic Creutzfeld-Jakob diseases (sCJD) (49 definite, 24 probable), with a median age at onset of 66 years. The clinical presentation was dementia in 29 cases, ataxia in 14 and visual symptoms in five. The median survival was 3 months. The 14-3-3 assay was positive in 93% cases, 62% presented periodic sharp wave complexes (PSWC) in EEG but only 18% the typical signs on MRI. Forty-eight sCJD were studied for codon 129 PRNP polymorphism: 69% were methionine/methionine (M/M), 14.5% valine/valine (V/V) and 16.5% M/V. Six out of seven V/V cases did not present PSWC and in two survival was longer than 20 months. Eleven cases (13%) were genetic: five familial fatal insomnia and six familial CJD (fCJD). Up to four (67%) fCJD lacked family history of disease, two presented seizures early at onset and one neurosensorial deafness. The only iatrogenic case was related to a dura mater graft. No case of variant CJD was registered. The study confirms in our population the consistent pattern reported worldwide on human prion diseases. Atypical features were seen more frequently in sporadic 129 V/V CJD and fCJD cases.

Atypical clinical course subacute sclerosing panencephalitis presenting as acute Encephalitis

PubMed Central

Komur, Mustafa; Arslankoylu, Ali E; Okuyaz, Cetin; Kuyucu, Necdet

2012-01-01

We report a 14-year-old boy who presented with loss of consciousness and gait instability. The electroencephalogram (EEG) showed generalized slowing with irregular activity and cerebral magnetic imaging revealed asymmetrical nonspecific signals on basal ganglia. His second electroencephalogram revealed periodical generalized high-voltage slow wave complexes which did not disappear with diazepam induction. Subacute sclerosing panencephalitis (SSPE) was considered and the diagnosis was confirmed with the identification of measles antibodies in cerebrospinal fluid. Our findings show that SSPE should be in mind in the differential diagnosis of meningoencephalitis and acute disseminated encephalomyelitis and highlight the significance of EEG in the diagnosis of unidentified cases. PMID:23248691

A Comparative Study of Standardized Infinity Reference and Average Reference for EEG of Three Typical Brain States

PubMed Central

Zheng, Gaoxing; Qi, Xiaoying; Li, Yuzhu; Zhang, Wei; Yu, Yuguo

2018-01-01

The choice of different reference electrodes plays an important role in deciphering the functional meaning of electroencephalography (EEG) signals. In recent years, the infinity zero reference using the reference electrode standard technique (REST) has been increasingly applied, while the average reference (AR) was generally advocated as the best available reference option in previous classical EEG studies. Here, we designed EEG experiments and performed a direct comparison between the influences of REST and AR on EEG-revealed brain activity features for three typical brain behavior states (eyes-closed, eyes-open and music-listening). The analysis results revealed the following observations: (1) there is no significant difference in the alpha-wave-blocking effect during the eyes-open state compared with the eyes-closed state for both REST and AR references; (2) there was clear frontal EEG asymmetry during the resting state, and the degree of lateralization under REST was higher than that under AR; (3) the global brain functional connectivity density (FCD) and local FCD have higher values for REST than for AR under different behavior states; and (4) the value of the small-world network characteristic in the eyes-closed state is significantly (in full, alpha, beta and gamma frequency bands) higher than that in the eyes-open state, and the small-world effect under the REST reference is higher than that under AR. In addition, the music-listening state has a higher small-world network effect than the eyes-closed state. The above results suggest that typical EEG features might be more clearly presented by applying the REST reference than by applying AR when using a 64-channel recording. PMID:29593490

Neurocognitive and neurobehavioral disabilities in Epilepsy with Electrical Status Epilepticus in slow sleep (ESES) and related syndromes.

PubMed

Raha, Sarbani; Shah, Urvashi; Udani, Vrajesh

2012-11-01

The aims of this study were to assess the cognitive and behavioral problems of patients with Epilepsy with Electrical Status Epilepticus in slow sleep (ESES) and related syndromes and to review their EEG (electroencephalography) findings and treatment options. Fourteen patients with ESES were evaluated and treated in 2010. Nine children had continuous spike and wave during slow-wave sleep (CSWS)/ESES syndrome, 3 had Atypical BECTS (benign epilepsy with centrotemporal spikes), 1 had Opercular syndrome, and 1 had Landau-Kleffner syndrome. The duration of ESES ranged from 6 to 52 months. Eleven (91%) children had behavioral issues, most prominent being hyperactivity. Seven of the 13 children (53%) showed evidence of borderline to moderate cognitive impairment. A total of 28 EEG findings of ESES were analyzed for SWI (spike-wave index). Antiepileptic drugs received by the patients included valproate, clobazam, levetiracetam, and others. Eleven patients had been treated with oral steroids and it was found to be efficacious in seven (63%). Disabilities caused by ESES affect multiple domains. Patients with an SWI>50% should be followed up frequently with neuropsychological assessments. Steroids appear to be effective, although there is a need to standardize the dose and duration of treatment. Copyright © 2012 Elsevier Inc. All rights reserved.

Generic short-time propagation of sharp-boundaries wave packets

NASA Astrophysics Data System (ADS)

Granot, E.; Marchewka, A.

2005-11-01

A general solution to the "shutter" problem is presented. The propagation of an arbitrary initially bounded wave function is investigated, and the general solution for any such function is formulated. It is shown that the exact solution can be written as an expression that depends only on the values of the function (and its derivatives) at the boundaries. In particular, it is shown that at short times (t << 2mx2/hbar, where x is the distance to the boundaries) the wave function propagation depends only on the wave function's values (or its derivatives) at the boundaries of the region. Finally, we generalize these findings to a non-singular wave function (i.e., for wave packets with finite-width boundaries) and suggest an experimental verification.

Electroencephalographic Recordings During Withdrawal of Life-Sustaining Therapy Until 30 Minutes After Declaration of Death.

PubMed

Norton, Loretta; Gibson, Raechelle M; Gofton, Teneille; Benson, Carolyn; Dhanani, Sonny; Shemie, Sam D; Hornby, Laura; Ward, Roxanne; Young, G Bryan

2017-03-01

The timing of the circulatory determination of death for organ donation presents a medical and ethical challenge. Concerns have been raised about the timing of electrocerebral inactivity in relation to the cessation of circulatory function in organ donation after cardio-circulatory death. Nonprocessed electroencephalographic (EEG) measures have not been characterized and may provide insight into neurological function during this process. We assessed electrocortical data in relation to cardiac function after withdrawal of life-sustaining therapy and in the postmortem period after cardiac arrest for four patients in a Canadian intensive care unit. Subhairline EEG and cardio-circulatory monitoring including electrocardiogram, arterial blood pressure (ABP), and oxygen saturation were captured. Electrocerebral inactivity preceded the cessation of the cardiac rhythm and ABP in three patients. In one patient, single delta wave bursts persisted following the cessation of both the cardiac rhythm and ABP. There was a significant difference in EEG amplitude between the 30-minute period before and the 5-minute period following ABP cessation for the group, but we did not observe any well-defined EEG states following the early cardiac arrest period. In a case series of four patients, EEG inactivity preceded electrocardiogram and ABP inactivity during the dying process in three patients. Further study of the electroencephalogram during the withdrawal of life sustaining therapies will add clarity to medical, ethical, and legal concerns for donation after circulatory determined death.

A neural network method for detection of obstructive sleep apnea and narcolepsy based on pupil size and EEG.

PubMed

Liu, D; Pang, Z; Lloyd, S R

2008-02-01

Electroencephalogram (EEG) is able to indicate states of mental activity ranging from concentrated cognitive efforts to sleepiness. Such mental activity can be reflected by EEG energy. In particular, intrusion of EEG theta wave activity into the beta activity of active wakefulness has been interpreted as ensuing sleepiness. Pupil behavior can also provide information regarding alertness. This paper develops an innovative signal classification method that is capable of differentiating subjects with sleep disorders which cause excessive daytime sleepiness (EDS) from normal control subjects who do not have a sleep disorder based on EEG and pupil size. Subjects with sleep disorders include persons with untreated obstructive sleep apnea (OSA) and narcolepsy. The Yoss pupil staging rule is used to scale levels of wakefulness and at the same time theta energy ratios are calculated from the same 2-s sliding windows by Fourier or wavelet transforms. Then, an artificial neural network (NN) of modified adaptive resonance theory (ART2) is utilized to identify the two groups within a combined group of subjects including those with OSA and healthy controls. This grouping from the NN is then compared with the actual diagnostic classification of subjects as OSA or controls and is found to be 91% accurate in differentiating between the two groups. The same algorithm results in 90% correct differentiation between narcoleptic and control subjects.

An experimental/computational study of sharp fin induced shock wave/turbulent boundary layer interactions at Mach 5 - Experimental results

NASA Technical Reports Server (NTRS)

Rodi, Patrick E.; Dolling, David S.

1992-01-01

A combined experimental/computational study has been performed of sharp fin induced shock wave/turbulent boundary layer interactions at Mach 5. The current paper focuses on the experiments and analysis of the results. The experimental data include mean surface heat transfer, mean surface pressure distributions and surface flow visualization for fin angles of attack of 6, 8, 10, 12, 14 and 16-degrees at Mach 5 under a moderately cooled wall condition. Comparisons between the results and correlations developed earlier show that Scuderi's correlation for the upstream influence angle (recast in a conical form) is superior to other such correlations in predicting the current results, that normal Mach number based correlations for peak pressure heat transfer are adequate and that the initial heat transfer peak can be predicted using pressure-interaction theory.

Boundary Layer Instabilities Generated by Freestream Laser Perturbations

NASA Technical Reports Server (NTRS)

Chou, Amanda; Schneider, Steven P.

2015-01-01

A controlled, laser-generated, freestream perturbation was created in the freestream of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT). The freestream perturbation convected downstream in the Mach-6 wind tunnel to interact with a flared cone model. The geometry of the flared cone is a body of revolution bounded by a circular arc with a 3-meter radius. Fourteen PCB 132A31 pressure transducers were used to measure a wave packet generated in the cone boundary layer by the freestream perturbation. This wave packet grew large and became nonlinear before experiencing natural transition in quiet flow. Breakdown of this wave packet occurred when the amplitude of the pressure fluctuations was approximately 10% of the surface pressure for a nominally sharp nosetip. The initial amplitude of the second mode instability on the blunt flared cone is estimated to be on the order of 10 -6 times the freestream static pressure. The freestream laser-generated perturbation was positioned upstream of the model in three different configurations: on the centerline, offset from the centerline by 1.5 mm, and offset from the centerline by 3.0 mm. When the perturbation was offset from the centerline of a blunt flared cone, a larger wave packet was generated on the side toward which the perturbation was offset. The offset perturbation did not show as much of an effect on the wave packet on a sharp flared cone as it did on a blunt flared cone.

Automatic sleep stage classification based on EEG signals by using neural networks and wavelet packet coefficients.

PubMed

Ebrahimi, Farideh; Mikaeili, Mohammad; Estrada, Edson; Nazeran, Homer

2008-01-01

Currently in the world there is an alarming number of people who suffer from sleep disorders. A number of biomedical signals, such as EEG, EMG, ECG and EOG are used in sleep labs among others for diagnosis and treatment of sleep related disorders. The usual method for sleep stage classification is visual inspection by a sleep specialist. This is a very time consuming and laborious exercise. Automatic sleep stage classification can facilitate this process. The definition of sleep stages and the sleep literature show that EEG signals are similar in Stage 1 of non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Therefore, in this work an attempt was made to classify four sleep stages consisting of Awake, Stage 1 + REM, Stage 2 and Slow Wave Stage based on the EEG signal alone. Wavelet packet coefficients and artificial neural networks were deployed for this purpose. Seven all night recordings from Physionet database were used in the study. The results demonstrated that these four sleep stages could be automatically discriminated from each other with a specificity of 94.4 +/- 4.5%, a of sensitivity 84.2+3.9% and an accuracy of 93.0 +/- 4.0%.

Design of a 32-Channel EEG System for Brain Control Interface Applications

PubMed Central

Wang, Ching-Sung

2012-01-01

This study integrates the hardware circuit design and the development support of the software interface to achieve a 32-channel EEG system for BCI applications. Since the EEG signals of human bodies are generally very weak, in addition to preventing noise interference, it also requires avoiding the waveform distortion as well as waveform offset and so on; therefore, the design of a preamplifier with high common-mode rejection ratio and high signal-to-noise ratio is very important. Moreover, the friction between the electrode pads and the skin as well as the design of dual power supply will generate DC bias which affects the measurement signals. For this reason, this study specially designs an improved single-power AC-coupled circuit, which effectively reduces the DC bias and improves the error caused by the effects of part errors. At the same time, the digital way is applied to design the adjustable amplification and filter function, which can design for different EEG frequency bands. For the analog circuit, a frequency band will be taken out through the filtering circuit and then the digital filtering design will be used to adjust the extracted frequency band for the target frequency band, combining with MATLAB to design man-machine interface for displaying brain wave. Finally the measured signals are compared to the traditional 32-channel EEG signals. In addition to meeting the IFCN standards, the system design also conducted measurement verification in the standard EEG isolation room in order to demonstrate the accuracy and reliability of this system design. PMID:22778545

[Electrophysiological correlates of efficacy of nootropic drugs in the treatment of consequences of traumatic brain injury in adolescents].

PubMed

Iznak, E V; Iznak, A F; Pankratova, E A; Zavadenko, N N; Guzilova, L S; Guzilova, Iu I

2010-01-01

To assess objectively a dynamics of brain functional state, EEG spectral power and peak latency of the P300 component of cognitive auditory evoked potentials have been analyzed in adolescents during the course of nootropic therapy of residual asthenic consequences of traumatic brain injury (ICD-10 F07.2). The study included 76 adolescents, aged 12-18 years, who have undergone severe closed head trauma with brain commotion 1/2--5 years ago. Patients have been divided into 3 groups treated during one month with cerebrolysin, piracetam or magne-B6, respectively. After the end of the nootropic therapy, 77% of patients treated with cerebrolysin as well as 50% of patients treated with piracetam and magne-B6 have demonstrated the positive dynamics of their brain functional state that manifested itself in the appearance of occipital EEG alpha rhythm or in the increase of its spectral power; in the normalization of alpha rhythm frequency; in the decrease in the spectral power of slow wave (theta and delta) EEG activity, in the amount (up to the disappearance) of paroxysmal EEG activity, in the EEG response to hyperventilation and in the shortening of the P300 peak latency. Such positive changes of neurophysiological parameters have been associated with the improvement of clinical conditions of patients and correlated significantly with the dynamics of psychometric scores of attention and memory.

Imaging Strong Lateral Heterogeneities with USArray using Body-to-Surface Wave Scattering

NASA Astrophysics Data System (ADS)

Yu, C.; Zhan, Z.; Hauksson, E.; Cochran, E. S.

2017-12-01

Seismic scattering is commonly observed and results from wave propagation in heterogeneous medium. Yet, deterministic characterization of scatterers remains challenging. In this study, we analyze broadband waveforms recorded by the USArray across the entire conterminous US. With array analysis, we observe strong scattered surface waves following the arrival of teleseismic body waves over several hundreds of kilometers. We use back-projection to locate the body-to-surface scattering sources, and detect strong scatterers both around and within the conterminous US. For the former, strong scattering is associated with pronounced bathymetric relief, such as the Patton Escarpment in the Southern California Continental Borderland. For the latter, scatterers are consistent with sharp lateral heterogeneities, such as near the Yellowstone hotspot and Southern California fault zones. We further model the body-to-surface wave scattering using finite-difference simulations. As an example, in the Southern California Continental Borderland a simplified 2-D bathymetric and crustal model are able to predict the arrival times and amplitudes of major scatterers. The modeling also suggests a relatively low shear wave velocity in the Continental Borderland. These observation of strong body-to-surface wave scattering and waveform modeling not only helps us image sharp heterogeneities but also are useful for assessing seismic hazard, including the calibration and refinement of seismic velocity models used to locate earthquakes and simulate strong ground motions.

Disrupting neural activity related to awake-state sharp wave-ripple complexes prevents hippocampal learning.

PubMed

Nokia, Miriam S; Mikkonen, Jarno E; Penttonen, Markku; Wikgren, Jan

2012-01-01

Oscillations in hippocampal local-field potentials (LFPs) reflect the crucial involvement of the hippocampus in memory trace formation: theta (4-8 Hz) oscillations and ripples (~200 Hz) occurring during sharp waves are thought to mediate encoding and consolidation, respectively. During sharp wave-ripple complexes (SPW-Rs), hippocampal cell firing closely follows the pattern that took place during the initial experience, most likely reflecting replay of that event. Disrupting hippocampal ripples using electrical stimulation either during training in awake animals or during sleep after training retards spatial learning. Here, adult rabbits were trained in trace eyeblink conditioning, a hippocampus-dependent associative learning task. A bright light was presented to the animals during the inter-trial interval (ITI), when awake, either during SPW-Rs or irrespective of their neural state. Learning was particularly poor when the light was presented following SPW-Rs. While the light did not disrupt the ripple itself, it elicited a theta-band oscillation, a state that does not usually coincide with SPW-Rs. Thus, it seems that consolidation depends on neuronal activity within and beyond the hippocampus taking place immediately after, but by no means limited to, hippocampal SPW-Rs.

EEG changes as heat stress reactions in rats irradiated by high intensity 35 GHz millimeter waves.

PubMed

Xie, Taorong; Pei, Jian; Cui, Yibin; Zhang, Jie; Qi, Hongxing; Chen, Shude; Qiao, Dengjiang

2011-06-01

As the application of millimeter waves for civilian and military use increases, the possibility of overexposure to millimeter waves will also increase. This paper attempts to evaluate stress reactions evoked by 35 GHz millimeter waves. The stress reactions in Sprague-Dawley (SD) rats were quantitatively studied by analyzing electroencephalogram (EEG) changes induced by overexposure to 35 GHz millimeter waves. The relative changes in average energy of the EEG and its wavelet decompositions were used for extracting the stress reaction indicators. Incident average power densities (IAPDs) of 35 GHz millimeter waves from 0.5 W cm(-2) to 7.5 W cm(-2) were employed to investigate the relation between irradiation dose and the stress reactions in the rats. Different stress reaction periods evoked by irradiation were quantitatively evaluated by EEG results. The results illustrate that stress reactions are more intense during the first part of the irradiation than during the later part. The skin temperature increase produced by millimeter wave irradiation is the principle reason for stress reactions and skin injuries. As expected, at the higher levels of irradiation, the reaction time decreases and the reaction intensity increases.

EEG Alpha and Beta Activity in Normal and Deaf Subjects.

ERIC Educational Resources Information Center

Waldron, Manjula; And Others

Electroencephalogram and task performance data were collected from three groups of young adult males: profoundly deaf Ss who signed from an early age, profoundly deaf Ss who only used oral (speech and speedreading) methods of communication, and normal hearing Ss. Alpha and Beta brain wave patterns over the Wernicke's area were compared across…

Neural Correlates of User-initiated Motor Success and Failure - A Brain-Computer Interface Perspective.

PubMed

Yazmir, Boris; Reiner, Miriam

2018-05-15

Any motor action is, by nature, potentially accompanied by human errors. In order to facilitate development of error-tailored Brain-Computer Interface (BCI) correction systems, we focused on internal, human-initiated errors, and investigated EEG correlates of user outcome successes and errors during a continuous 3D virtual tennis game against a computer player. We used a multisensory, 3D, highly immersive environment. Missing and repelling the tennis ball were considered, as 'error' (miss) and 'success' (repel). Unlike most previous studies, where the environment "encouraged" the participant to perform a mistake, here errors happened naturally, resulting from motor-perceptual-cognitive processes of incorrect estimation of the ball kinematics, and can be regarded as user internal, self-initiated errors. Results show distinct and well-defined Event-Related Potentials (ERPs), embedded in the ongoing EEG, that differ across conditions by waveforms, scalp signal distribution maps, source estimation results (sLORETA) and time-frequency patterns, establishing a series of typical features that allow valid discrimination between user internal outcome success and error. The significant delay in latency between positive peaks of error- and success-related ERPs, suggests a cross-talk between top-down and bottom-up processing, represented by an outcome recognition process, in the context of the game world. Success-related ERPs had a central scalp distribution, while error-related ERPs were centro-parietal. The unique characteristics and sharp differences between EEG correlates of error/success provide the crucial components for an improved BCI system. The features of the EEG waveform can be used to detect user action outcome, to be fed into the BCI correction system. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Generalized onset seizures with focal evolution (GOFE) - A unique seizure type in the setting of generalized epilepsy.

PubMed

Linane, Avriel; Lagrange, Andre H; Fu, Cary; Abou-Khalil, Bassel

2016-01-01

We report clinical and electrographic features of generalized onset seizures with focal evolution (GOFE) and present arguments for the inclusion of this seizure type in the seizure classification. The adult and pediatric Epilepsy Monitoring Unit databases at Vanderbilt Medical Center and Children's Hospital were screened to identify generalized onset seizures with focal evolution. We reviewed medical records for epilepsy characteristics, epilepsy risk factors, MRI abnormalities, neurologic examination, antiepileptic medications before and after diagnosis, and response to medications. We also reviewed ictal and interictal EEG tracings, as well as video-recorded semiology. Ten patients were identified, 7 males and 3 females. All of the patients developed generalized epilepsy in childhood or adolescence (ages 3-15years). Generalized onset seizures with focal evolution developed years after onset in 9 patients, with a semiology concerning for focal seizures or nonepileptic events. Ictal discharges had a generalized onset on EEG, described as either generalized spike-and-wave and/or polyspike-and-wave discharges, or generalized fast activity. This electrographic activity then evolved to focal rhythmic activity most commonly localized to one temporal or frontal region; five patients had multiple seizures evolving to focal activity in different regions of both hemispheres. The predominant interictal epileptiform activity included generalized spike-and-wave and/or polyspike-and-wave discharges in all patients. Taking into consideration all clinical and EEG data, six patients were classified with genetic (idiopathic) generalized epilepsy, and four were classified with structural/metabolic (symptomatic) generalized epilepsy. All of the patients had modifications to their medications following discharge, with three becoming seizure-free and five responding with >50% reduction in seizure frequency. Generalized onset seizures may occasionally have focal evolution with semiology suggestive of focal seizures, leading to a misdiagnosis of focal onset. This unique seizure type may occur with genetic as well as structural/metabolic forms of epilepsy. The identification of this seizure type may help clinicians choose appropriate medications, avoiding narrow spectrum agents known to aggravate generalized onset seizures. Copyright © 2015 Elsevier Inc. All rights reserved.

Olfactory Hallucinations without Clinical Motor Activity: A Comparison of Unirhinal with Birhinal Phantosmia

PubMed Central

Henkin, Robert I.; Potolicchio, Samuel J.; Levy, Lucien M.

2013-01-01

Olfactory hallucinations without subsequent myoclonic activity have not been well characterized or understood. Herein we describe, in a retrospective study, two major forms of olfactory hallucinations labeled phantosmias: one, unirhinal, the other, birhinal. To describe these disorders we performed several procedures to elucidate similarities and differences between these processes. From 1272, patients evaluated for taste and smell dysfunction at The Taste and Smell Clinic, Washington, DC with clinical history, neurological and otolaryngological examinations, evaluations of taste and smell function, EEG and neuroradiological studies 40 exhibited cyclic unirhinal phantosmia (CUP) usually without hyposmia whereas 88 exhibited non-cyclic birhinal phantosmia with associated symptomology (BPAS) with hyposmia. Patients with CUP developed phantosmia spontaneously or after laughing, coughing or shouting initially with spontaneous inhibition and subsequently with Valsalva maneuvers, sleep or nasal water inhalation; they had frequent EEG changes usually ipsilateral sharp waves. Patients with BPAS developed phantosmia secondary to several clinical events usually after hyposmia onset with few EEG changes; their phantosmia could not be initiated or inhibited by any physiological maneuver. CUP is uncommonly encountered and represents a newly defined clinical syndrome. BPAS is commonly encountered, has been observed previously but has not been clearly defined. Mechanisms responsible for phantosmia in each group were related to decreased gamma-aminobutyric acid (GABA) activity in specific brain regions. Treatment which activated brain GABA inhibited phantosmia in both groups. PMID:24961619

Design of a 32-channel EEG system for brain control interface applications.

PubMed

Wang, Ching-Sung

2012-01-01

This study integrates the hardware circuit design and the development support of the software interface to achieve a 32-channel EEG system for BCI applications. Since the EEG signals of human bodies are generally very weak, in addition to preventing noise interference, it also requires avoiding the waveform distortion as well as waveform offset and so on; therefore, the design of a preamplifier with high common-mode rejection ratio and high signal-to-noise ratio is very important. Moreover, the friction between the electrode pads and the skin as well as the design of dual power supply will generate DC bias which affects the measurement signals. For this reason, this study specially designs an improved single-power AC-coupled circuit, which effectively reduces the DC bias and improves the error caused by the effects of part errors. At the same time, the digital way is applied to design the adjustable amplification and filter function, which can design for different EEG frequency bands. For the analog circuit, a frequency band will be taken out through the filtering circuit and then the digital filtering design will be used to adjust the extracted frequency band for the target frequency band, combining with MATLAB to design man-machine interface for displaying brain wave. Finally the measured signals are compared to the traditional 32-channel EEG signals. In addition to meeting the IFCN standards, the system design also conducted measurement verification in the standard EEG isolation room in order to demonstrate the accuracy and reliability of this system design.

Sleep EEG Provides Evidence that Cortical Changes Persist into Late Adolescence

PubMed Central

Tarokh, Leila; Van Reen, Eliza; LeBourgeois, Monique; Seifer, Ronald; Carskadon, Mary A.

2011-01-01

Study Objectives: To examine developmental changes in the human sleep electroencephalogram (EEG) during late adolescence. Setting: A 4-bed sleep laboratory. Participants: Fourteen adolescents (5 boys) were studied at ages 15 or 16 (initial) and again at ages 17 to 19 (follow-up). Interventions: N/A Measurements and Results: All-night polysomnography was recorded at each assessment and scored according to the criteria of Rechtschaffen and Kales. A 27% decline in duration of slow wave sleep, and a 22% increase of stage 2 sleep was observed from the initial to the follow-up session. All-night spectral analysis of 2 central and 2 occipital leads revealed a significant decline of NREM and REM sleep EEG power with increasing age across frequencies in both states. Time-frequency analysis revealed that the decline in power was consistent across the night for all bands except the delta band. The decreases in power were most pronounced over the left central (C3/A2) and right occipital (O2/A1) derivations. Conclusions: Using longitudinal data, we show that the developmental changes to the sleeping EEG that begin in early adolescence continue into late adolescence. As with early adolescents, we observed hemispheric asymmetry in the decline of sleep EEG power. This decline was state and frequency nonspecific, suggesting that it may be due to the pruning of synapses known to occur during adolescence. Citation: Tarokh L; Van Reen E; LeBourgeois M; Seifer R; Carskadon MA. Sleep EEG provides evidence that cortical changes persist into late adolescence. SLEEP 2011;34(10):1385–1393. PMID:21966070

The Development of Drift Wave Turbulence in Magnetic Reconnection

NASA Astrophysics Data System (ADS)

McMurtrie, L.; Drake, J. F.; Swisdak, M. M.

2013-12-01

An important feature in collisionless magnetic reconnection is the development of sharp discontinuities along the separatrices bounding the Alfvenic outflow. The typical scale length of these features is ρs (the Larmor radius based on the sound speed) for guide field reconnection. Temperature gradients in the inflowing plasma (as might be found in the magnetopause) can lead to instabilities at these separatrices, specifically drift wave turbulence. We present standalone 2D and 3D PIC simulations of drift wave turbulence to investigate scaling properties and growth rates. Further investigations of the relative importance of drift wave turbulence in the development of reconnection will also be considered.

Rectal diazepam in the treatment of absence status: a pharmacodynamic study

PubMed Central

Milligan, Norman; Dhillon, Soraya; Richens, Alan; Oxley, Jolyon

1981-01-01

Rectal administration of diazepam is highly effective in terminating absence status as judged by reduction of spike-wave activity in the EEG. Pharmacokinetic studies indicate that diazepam can have antiepileptic properties at serum levels well below those previously reported as being necessary to achieve a therapeutic effect. PMID:7310409

A method for classification of transient events in EEG recordings: application to epilepsy diagnosis.

PubMed

Tzallas, A T; Karvelis, P S; Katsis, C D; Fotiadis, D I; Giannopoulos, S; Konitsiotis, S

2006-01-01

The aim of the paper is to analyze transient events in inter-ictal EEG recordings, and classify epileptic activity into focal or generalized epilepsy using an automated method. A two-stage approach is proposed. In the first stage the observed transient events of a single channel are classified into four categories: epileptic spike (ES), muscle activity (EMG), eye blinking activity (EOG), and sharp alpha activity (SAA). The process is based on an artificial neural network. Different artificial neural network architectures have been tried and the network having the lowest error has been selected using the hold out approach. In the second stage a knowledge-based system is used to produce diagnosis for focal or generalized epileptic activity. The classification of transient events reported high overall accuracy (84.48%), while the knowledge-based system for epilepsy diagnosis correctly classified nine out of ten cases. The proposed method is advantageous since it effectively detects and classifies the undesirable activity into appropriate categories and produces a final outcome related to the existence of epilepsy.

Spike-like solitary waves in incompressible boundary layers driven by a travelling wave.

PubMed

Feng, Peihua; Zhang, Jiazhong; Wang, Wei

2016-06-01

Nonlinear waves produced in an incompressible boundary layer driven by a travelling wave are investigated, with damping considered as well. As one of the typical nonlinear waves, the spike-like wave is governed by the driven-damped Benjamin-Ono equation. The wave field enters a completely irregular state beyond a critical time, increasing the amplitude of the driving wave continuously. On the other hand, the number of spikes of solitary waves increases through multiplication of the wave pattern. The wave energy grows in a sequence of sharp steps, and hysteresis loops are found in the system. The wave energy jumps to different levels with multiplication of the wave, which is described by winding number bifurcation of phase trajectories. Also, the phenomenon of multiplication and hysteresis steps is found when varying the speed of driving wave as well. Moreover, the nature of the change of wave pattern and its energy is the stability loss of the wave caused by saddle-node bifurcation.

Comparison of simultaneously recorded [H2(15)O]-PET and LORETA during cognitive and pharmacological activation.

PubMed

Gamma, Alex; Lehmann, Dietrich; Frei, Edi; Iwata, Kazuki; Pascual-Marqui, Roberto D; Vollenweider, Franz X

2004-06-01

The complementary strengths and weaknesses of established functional brain imaging methods (high spatial, low temporal resolution) and EEG-based techniques (low spatial, high temporal resolution) make their combined use a promising avenue for studying brain processes at a more fine-grained level. However, this strategy requires a better understanding of the relationship between hemodynamic/metabolic and neuroelectric measures of brain activity. We investigated possible correspondences between cerebral blood flow (CBF) as measured by [H2O]-PET and intracerebral electric activity computed by Low Resolution Brain Electromagnetic Tomography (LORETA) from scalp-recorded multichannel EEG in healthy human subjects during cognitive and pharmacological stimulation. The two imaging modalities were compared by descriptive, correlational, and variance analyses, the latter carried out using statistical parametric mapping (SPM99). Descriptive visual comparison showed a partial overlap between the sets of active brain regions detected by the two modalities. A number of exclusively positive correlations of neuroelectric activity with regional CBF were found across the whole EEG frequency range, including slow wave activity, the latter finding being in contrast to most previous studies conducted in patients. Analysis of variance revealed an extensive lack of statistically significant correspondences between brain activity changes as measured by PET vs. EEG-LORETA. In general, correspondences, to the extent they were found, were dependent on experimental condition, brain region, and EEG frequency. Copyright 2004 Wiley-Liss, Inc.

Electroencephalographic features of benign adult familial myoclonic epilepsy.

PubMed

Toyota, Tomoko; Akamatsu, Naoki; Tanaka, Akihiro; Tsuji, Sadatoshi; Uozumi, Takenori

2014-02-01

To investigate electroencephalographic (EEG) features of benign adult familial myoclonic epilepsy (BAFME). We reviewed interictal EEG features in patients with BAFME treated between April 2005 and November 2012 at a tertiary referral center. The diagnostic criteria for BAFME were the presence of infrequent generalized tonic-clonic seizures, myoclonus or myoclonic seizures, and autosomal dominant inheritance. Interictal EEG findings of epilepsy with generalized tonic-clonic seizure only (EGTCS) were reviewed for comparison. We randomly selected 10 generalized spike/polyspike and wave complexes (GSW) for each BAFME patient and measured the duration of them. Photic stimulation and hyperventilation were performed in all. Nineteen (eight men, 11 women) patients with BAFME were included in this study. The mean frequency of GSW was 4.3±1.0Hz (mean±SD, n=14) in BAFME and 3.2±0.8Hz (n=10) in EGTCS. There was a statistically significant difference (p=0.008) between the two. Photoparoxysmal responses (PPR) were noted in 18 (95%) patients with BAFME but 1 (10%) with EGTCS. Faster frequency of GSW, compared with that in EGTCS, accompanied by PPR may be characteristic EEG features of BAFME. These findings may lead the diagnosis of BAFME. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Hippocampal coupling with cortical and subcortical structures in the context of memory consolidation.

PubMed

Skelin, Ivan; Kilianski, Scott; McNaughton, Bruce L

2018-04-13

Memory consolidation is a gradual process through which episodic memories become incorporated into long-term 'semantic' representations. It likely involves reactivation of neural activity encoding the recent experience during non-REM sleep. A critical prerequisite for memory consolidation is precise coordination of reactivation events between the hippocampus and cortical/subcortical structures, facilitated by the coupling of local field potential (LFP) oscillations (slow oscillations, sleep spindles and sharp wave/ripples) between these structures. We review the rapidly expanding literature on the qualitative and quantitative aspects of hippocampal oscillatory and neuronal coupling with cortical/subcortical structures in the context of memory reactivation. Reactivation in the hippocampus and cortical/subcortical structures is tightly coupled with sharp wave/ripples. Hippocampal-cortical/subcortical coupling is rich in dimensionality and this dimensionality is likely underestimated due to the limitations of the current methodology. Copyright © 2018 Elsevier Inc. All rights reserved.

Brain-computer interface design using alpha wave

NASA Astrophysics Data System (ADS)

Zhao, Hai-bin; Wang, Hong; Liu, Chong; Li, Chun-sheng

2010-01-01

A brain-computer interface (BCI) is a novel communication system that translates brain activity into commands for a computer or other electronic devices. BCI system based on non-invasive scalp electroencephalogram (EEG) has become a hot research area in recent years. BCI technology can help improve the quality of life and restore function for people with severe motor disabilities. In this study, we design a real-time asynchronous BCI system using Alpha wave. The basic theory of this BCI system is alpha wave-block phenomenon. Alpha wave is the most prominent wave in the whole realm of brain activity. This system includes data acquisition, feature selection and classification. The subject can use this system easily and freely choose anyone of four commands with only short-time training. The results of the experiment show that this BCI system has high classification accuracy, and has potential application for clinical engineering and is valuable for further research.

Designing EEG Neurofeedback Procedures to Enhance Open-Ended versus Closed-Ended Creative Potentials

ERIC Educational Resources Information Center

Lin, Wei-Lun; Shih, Yi-Ling

2016-01-01

Recent empirical evidence demonstrated that open-ended creativity (which refers to creativity measures that require various and numerous responses, such as divergent thinking) correlated with alpha brain wave activation, whereas closed-ended creativity (which refers to creativity measures that ask for one final correct answer, such as insight…

Neurologic abnormalities in murderers.

PubMed

Blake, P Y; Pincus, J H; Buckner, C

1995-09-01

Thirty-one individuals awaiting trial or sentencing for murder or undergoing an appeal process requested a neurologic examination through legal counsel. We attempted in each instance to obtain EEG, MRI or CT, and neuropsychological testing. Neurologic examination revealed evidence of "frontal" dysfunction in 20 (64.5%). There were symptoms or some other evidence of temporal lobe abnormality in nine (29%). We made a specific neurologic diagnosis in 20 individuals (64.5%), including borderline or full mental retardation (9) and cerebral palsy (2), among others. Neuropsychological testing revealed abnormalities in all subjects tested. There were EEG abnormalities in eight of the 20 subjects tested, consisting mainly of bilateral sharp waves with slowing. There were MRI or CT abnormalities in nine of the 19 subjects tested, consisting primarily of atrophy and white matter changes. Psychiatric diagnoses included paranoid schizophrenia (8), dissociative disorder (4), and depression (9). Virtually all subjects had paranoid ideas and misunderstood social situations. There was a documented history of profound, protracted physical abuse in 26 (83.8%) and of sexual abuse in 10 (32.3%). It is likely that prolonged, severe physical abuse, paranoia, and neurologic brain dysfunction interact to form the matrix of violent behavior.

EEG in children with spelling disabilities.

PubMed

Byring, R F; Salmi, T K; Sainio, K O; Orn, H P

1991-10-01

A total of 23 13-year-old boys with spelling disabilities and 21 matched controls were studied. EEG was recorded for visual and quantitative analysis, including FFT band powers and normalized slope descriptors (NSD). Visual analysis showed general excess of slow activity, as well as an excess of temporal slow wave activity in the index group. Quantitative analysis showed low alpha and beta powers, and low "activity" and high "complexity" (NSD) in parieto-occipital derivations in the index group. Quantitative EEG (qEEG) parameter ratios between temporal and parieto-occipital derivations were increased in the index group, implying a lack of spatial differentiation in these EEGs. In covariance analysis the qEEG parameter differences between the index group and controls were partly explained by the neurotic traits made evident in psychological tests. This implies that psychopathological artifacts should be considered in qEEG examinations of children with cognitive handicaps. Differences in anterior/posterior qEEG ratios were, however, little affected by any confounding factors. Thus these qEEG ratios seem potentially useful in clinical assessments of children with learning disabilities.

Predictable internal brain dynamics in EEG and its relation to conscious states

PubMed Central

Yoo, Jaewook; Kwon, Jaerock; Choe, Yoonsuck

2014-01-01

Consciousness is a complex and multi-faceted phenomenon defying scientific explanation. Part of the reason why this is the case is due to its subjective nature. In our previous computational experiments, to avoid such a subjective trap, we took a strategy to investigate objective necessary conditions of consciousness. Our basic hypothesis was that predictive internal dynamics serves as such a condition. This is in line with theories of consciousness that treat retention (memory), protention (anticipation), and primary impression as the tripartite temporal structure of consciousness. To test our hypothesis, we analyzed publicly available sleep and awake electroencephalogram (EEG) data. Our results show that EEG signals from awake or rapid eye movement (REM) sleep states have more predictable dynamics compared to those from slow-wave sleep (SWS). Since awakeness and REM sleep are associated with conscious states and SWS with unconscious or less consciousness states, these results support our hypothesis. The results suggest an intricate relationship among prediction, consciousness, and time, with potential applications to time perception and neurorobotics. PMID:24917813

Confused or not Confused?: Disentangling Brain Activity from EEG Data Using Bidirectional LSTM Recurrent Neural Networks.

PubMed

Ni, Zhaoheng; Yuksel, Ahmet Cem; Ni, Xiuyan; Mandel, Michael I; Xie, Lei

2017-08-01

Brain fog, also known as confusion, is one of the main reasons for low performance in the learning process or any kind of daily task that involves and requires thinking. Detecting confusion in a human's mind in real time is a challenging and important task that can be applied to online education, driver fatigue detection and so on. In this paper, we apply Bidirectional LSTM Recurrent Neural Networks to classify students' confusion in watching online course videos from EEG data. The results show that Bidirectional LSTM model achieves the state-of-the-art performance compared with other machine learning approaches, and shows strong robustness as evaluated by cross-validation. We can predict whether or not a student is confused in the accuracy of 73.3%. Furthermore, we find the most important feature to detecting the brain confusion is the gamma 1 wave of EEG signal. Our results suggest that machine learning is a potentially powerful tool to model and understand brain activity.

Effects of the Kelvin-Helmholtz surface instability on supersonic jets

NASA Technical Reports Server (NTRS)

Hardee, P. E.

1982-01-01

An exact numerical calculation is provided for of linear growth and phase velocity of Kelvin-Helmholtz unstable wave modes on a supersonic jet of cylindrical cross section. An expression for the maximally unstable wavenumber of each wave mode is found. Provided a sharp velocity discontinuity exists all wave modes are unstable. A combination of rapid jet expansion and velocity shear across a jet can effectively stabilize all wave modes. The more likely case of slow jet expansion and of velocity shear at the jet surface allows wave modes with maximally unstable wavelength longer than or on the order of the jet radius to grow. The relative energy in different wave modes and effect on the jet is investigated. Energy input into a jet resulting from surface instability is discussed.

Coordinated Excitation and Inhibition of Prefrontal Ensembles During Awake Hippocampal Sharp-Wave Ripple Events

PubMed Central

Jadhav, Shantanu P.; Rothschild, Gideon; Roumis, Demetris K.; Frank, Loren M.

2016-01-01

SUMMARY Interactions between the hippocampus and prefrontal cortex (PFC) are critical for learning and memory. Hippocampal activity during awake sharp wave ripple (SWR) events is important for spatial learning, and hippocampal SWR activity often represents past or potential future experiences. Whether or how this reactivation engages the PFC, and how reactivation might interact with ongoing patterns of PFC activity remains unclear. We recorded hippocampal CA1 and PFC activity in animals learning spatial tasks and found that many PFC cells showed spiking modulation during SWRs. Unlike in CA1, SWR-related activity in PFC comprised both excitation and inhibition of distinct populations. Within individual SWRs, excitation activated PFC cells with representations related to the concurrently reactivated hippocampal representation, while inhibition suppressed PFC cells with unrelated representations. Thus, awake SWRs mark times of strong coordination between hippocampus and PFC that reflects structured reactivation of representations related to ongoing experience. PMID:26971950

Involvement of Mossy Cells in Sharp Wave-Ripple Activity In Vitro.

PubMed

Swaminathan, Aarti; Wichert, Ines; Schmitz, Dietmar; Maier, Nikolaus

2018-05-29

The role of mossy cells (MCs) of the hippocampal dentate area has long remained mysterious. Recent research has begun to unveil their significance in spatial computation of the hippocampus. Here, we used an in vitro model of sharp wave-ripple complexes (SWRs), which contribute to hippocampal memory formation, to investigate MC involvement in this fundamental population activity. We find that a significant fraction of MCs (∼47%) is recruited into the active neuronal network during SWRs in the CA3 area. Moreover, MCs receive pronounced, ripple-coherent, excitatory and inhibitory synaptic input. Finally, we find evidence for SWR-related synaptic activity in granule cells that is mediated by MCs. Given the widespread connectivity of MCs within and between hippocampi, our data suggest a role for MCs as a hub functionally coupling the CA3 and the DG during ripple-associated computations. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Sharp acoustic vortex focusing by Fresnel-spiral zone plates

NASA Astrophysics Data System (ADS)

Jiménez, Noé; Romero-García, Vicent; García-Raffi, Luis M.; Camarena, Francisco; Staliunas, Kestutis

2018-05-01

We report the optimal focusing of acoustic vortex beams by using flat lenses based on a Fresnel-spiral diffraction grating. The flat lenses are designed by spiral-shaped Fresnel zone plates composed of one or several arms. The constructive and destructive interferences of the diffracted waves by the spiral grating result in sharp acoustic vortex beams, following the focal laws obtained in analogy with the Fresnel zone plate lenses. In addition, we show that the number of arms determines the topological charge of the vortex, allowing the precise manipulation of the acoustic wave field by flat lenses. The experimental results in the ultrasonic regime show excellent agreement with the theory and full-wave numerical simulations. A comparison with beam focusing by Archimedean spirals also showing vortex focusing is given. The results of this work may have potential applications for particle trapping, ultrasound therapy, imaging, or underwater acoustic transmitters.

How do children fall asleep? A high-density EEG study of slow waves in the transition from wake to sleep.

PubMed

Spiess, Mathilde; Bernardi, Giulio; Kurth, Salome; Ringli, Maya; Wehrle, Flavia M; Jenni, Oskar G; Huber, Reto; Siclari, Francesca

2018-05-17

Slow waves, the hallmarks of non-rapid eye-movement (NREM) sleep, are thought to reflect maturational changes that occur in the cerebral cortex throughout childhood and adolescence. Recent work in adults has revealed evidence for two distinct synchronization processes involved in the generation of slow waves, which sequentially come into play in the transition to sleep. In order to understand how these two processes are affected by developmental changes, we compared slow waves between children and young adults in the falling asleep period. The sleep onset period (starting 30s before end of alpha activity and ending at the first slow wave sequence) was extracted from 72 sleep onset high-density EEG recordings (128 electrodes) of 49 healthy subjects (age 8-25). Using an automatic slow wave detection algorithm, the number, amplitude and slope of slow waves were analyzed and compared between children (age 8-11) and young adults (age 20-25). Slow wave number and amplitude increased linearly in the falling asleep period in children, while in young adults, isolated high-amplitude slow waves (type I) dominated initially and numerous smaller slow waves (type II) with progressively increasing amplitude occurred later. Compared to young adults, children displayed faster increases in slow wave amplitude and number across the falling asleep period in central and posterior brain regions, respectively, and also showed larger slow waves during wakefulness immediately prior to sleep. Children do not display the two temporally dissociated slow wave synchronization processes in the falling asleep period observed in adults, suggesting that maturational factors underlie the temporal segregation of these two processes. Our findings provide novel perspectives for studying how sleep-related behaviors and dreaming differ between children and adults. Copyright © 2018 Elsevier Inc. All rights reserved.

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens.

PubMed

Martin, Jessica E; Christensen, Karen; Vizzier-Thaxton, Yvonne; Mitchell, Malcolm A; McKeegan, Dorothy E F

2016-09-01

A novel approach to pre-slaughter stunning of chickens has been developed in which birds are rendered unconscious by progressive hypobaric hypoxia. Termed Low Atmospheric Pressure Stunning (LAPS), this approach involves application of gradual decompression lasting 280s according to a prescribed curve. We examined responses to LAPS by recording behaviour, electroencephalogram (EEG) and electrocardiogram (ECG) in individual male chickens, and interpreted these with regard to the welfare impact of the process. We also examined the effect of two temperature adjusted pressure curves on these responses. Broiler chickens were exposed to LAPS in 30 triplets (16 and 14 triplets assigned to each pressure curve). In each triplet, one bird was instrumented for recording of EEG and ECG while the behaviour of all three birds was observed. Birds showed a consistent sequence of behaviours during LAPS (ataxia, loss of posture, clonic convulsions and motionless) which were observed in all birds. Leg paddling, tonic convulsions, slow wing flapping, mandibulation, head shaking, open bill breathing, deep inhalation, jumping and vocalisation were observed in a proportion of birds. Spectral analysis of EEG responses at 2s intervals throughout LAPS revealed progressive decreases in median frequency at the same time as corresponding progressive increases in total power, followed later by decreases in total power as all birds exhibited isoelectric EEG and died. There was a very pronounced increase in total power at 50-60s into the LAPS cycle, which corresponded to dominance of the signal by high amplitude slow waves, indicating loss of consciousness. Slow wave EEG was seen early in the LAPS process, before behavioural evidence of loss of consciousness such as ataxia and loss of posture, almost certainly due to the fact that it was completely dark in the LAPS chamber. ECG recordings showed a pronounced bradycardia (starting on average 49.6s into LAPS), often associated with arrhythmia, until around 60s into LAPS when heart rate levelled off. There was a good correlation between behavioural, EEG and cardiac measures in relation to loss of consciousness which collectively provide a loss of consciousness estimate of around 60s. There were some effects of temperature adjusted pressure curves on behavioural latencies and ECG responses, but in general responses were consistent and very similar to those reported in previous research on controlled atmosphere stunning with inert gases. The results suggest that the process is humane (slaughter without avoidable fear, anxiety, pain, suffering and distress). In particular, the maintenance of slow wave EEG patterns in the early part of LAPS (while birds are still conscious) is strongly suggestive that LAPS is non-aversive, since we would expect this to be interrupted by pain or discomfort. Copyright © 2016 Elsevier Inc. All rights reserved.

Déjà vu phenomenon-related EEG pattern. Case report☆

PubMed Central

Vlasov, P.N.; Chervyakov, A.V.; Gnezditskii, V.V.

2013-01-01

Background Déjà vu (DV, from French déjà vu — “already seen”) is an aberration of psychic activity associated with transitory erroneous perception of novel circumstances, objects, or people as already known. Objective This study aimed to record the EEG pattern of déjà vu. Methods The subjects participated in a survey concerning déjà vu characteristics and underwent ambulatory EEG monitoring (12–16 h). Results In patients with epilepsy, DV episodes began with polyspike activity in the right temporal lobe region and, in some cases, ended with slow-wave theta–delta activity over the right hemisphere. There were no epileptic discharges in healthy respondents during DV. Conclusion Two types of déjà vu are suggested to exist: “pathological-epileptic” déjà vu, characteristic of patients with epilepsy and equivalent to an epileptic seizure, and “nonpathological-nonepileptic” déjà vu, which is characteristic of healthy people and psychological phenomenon. PMID:25667847

Enhanced Transmissions Through Three-dimensional Cascade Sharp Waveguide Bends Using C-slit Diaphragms.

PubMed

Yang, Rui; Hu, Bowei; Zhang, Aofang; Gao, Dongxing; Wang, Hui; Shi, Ayuan; Lei, Zhenya; Yang, Pei

2017-03-21

Transmission properties through sharp rectangular waveguide bends are investigated to determine the cut-off bending angles of the wave propagation. We show that a simple metallic diaphragm at the bending corner with properly devised sub-wavelength defect apertures of C-slits would be readily to turn on the transmissions with scarce reflections of the propagating modes, while preserving the integrity of the transmitting fields soon after the bends. In particularly, our design also demonstrates the capability of eliminating all the unwanted cavity resonant transmissions that exist in the three-dimensional cascade sharp waveguide bends, and solely let the desired signals travel along the whole passage of the waveguide. The present approach, using C-slit diaphragms to support the sharp bending behaviors of the guided waves with greatly enhanced transmissions, would be especially effective in constructing novel waveguides and pave the way for the development of more compact and miniaturized electromagnetic systems that exploit these waveguide bends.

myBrain: a novel EEG embedded system for epilepsy monitoring.

PubMed

Pinho, Francisco; Cerqueira, João; Correia, José; Sousa, Nuno; Dias, Nuno

2017-10-01

The World Health Organisation has pointed that a successful health care delivery, requires effective medical devices as tools for prevention, diagnosis, treatment and rehabilitation. Several studies have concluded that longer monitoring periods and outpatient settings might increase diagnosis accuracy and success rate of treatment selection. The long-term monitoring of epileptic patients through electroencephalography (EEG) has been considered a powerful tool to improve the diagnosis, disease classification, and treatment of patients with such condition. This work presents the development of a wireless and wearable EEG acquisition platform suitable for both long-term and short-term monitoring in inpatient and outpatient settings. The developed platform features 32 passive dry electrodes, analogue-to-digital signal conversion with 24-bit resolution and a variable sampling frequency from 250 Hz to 1000 Hz per channel, embedded in a stand-alone module. A computer-on-module embedded system runs a Linux ® operating system that rules the interface between two software frameworks, which interact to satisfy the real-time constraints of signal acquisition as well as parallel recording, processing and wireless data transmission. A textile structure was developed to accommodate all components. Platform performance was evaluated in terms of hardware, software and signal quality. The electrodes were characterised through electrochemical impedance spectroscopy and the operating system performance running an epileptic discrimination algorithm was evaluated. Signal quality was thoroughly assessed in two different approaches: playback of EEG reference signals and benchmarking with a clinical-grade EEG system in alpha-wave replacement and steady-state visual evoked potential paradigms. The proposed platform seems to efficiently monitor epileptic patients in both inpatient and outpatient settings and paves the way to new ambulatory clinical regimens as well as non-clinical EEG applications.

Physiological responses to low atmospheric pressure stunning and the implications for welfare.

PubMed

McKeegan, D E F; Sandercock, D A; Gerritzen, M A

2013-04-01

In low atmospheric pressure stunning (LAPS), poultry are rendered unconscious before slaughter by gradually reducing oxygen tension in the atmosphere to achieve a progressive anoxia. The effects of LAPS are not instantaneous, so there are legitimate welfare concerns around the experience of birds before loss of consciousness. Using self-contained telemetry logging units, high-quality continuous electroencephalogram (EEG) and electrocardiogram (EKG) recordings were obtained from 28 broiler chickens during exposure to LAPS in a commercial poultry processing plant. Application of LAPS was associated with changes in the EEG pattern in the form of increases in total power, decreases in mean frequency, and in particular, increases in slow-wave (delta) activity, indicating a gradual loss of consciousness. Increased delta wave activity was seen within 10 s of LAPS onset and consistently thereafter, peaking at 30 s into LAPS at which point the EEG signal shared characteristics with that of birds in a surgical plane of anesthesia. During LAPS, heart rate consistently decreased, with more pronounced bradycardia and arrhythmia observed after 30 s. No heart rate increases were observed in the period when the birds were potentially conscious. After an initial quiescent period, brief body movements (presumed to be ataxia/loss of posture) were seen on average at 39 s into the LAPS process. Later (after 120 s on average), artifacts related to clonic (wing flapping) and tonic (muscle spasms) convulsions were observed in the EKG recordings. Based on EEG analysis and body movement responses, a conservative estimate of time to loss of consciousness is approximately 40 s. The lack of behavioral responses indicating aversion or escape and absence of heart rate elevation in the conscious period strongly suggest that birds do not find LAPS induction distressing. Collectively, the results suggest that LAPS is a humane approach that has the potential to improve the welfare of poultry at slaughter by gradually inducing unconsciousness without distress, eliminating live shackling and ensuring every bird is adequately stunned before exansguination.

Impact of dronabinol on quantitative electroencephalogram (qEEG) measures of sleep in obstructive sleep apnea syndrome.

PubMed

Farabi, Sarah S; Prasad, Bharati; Quinn, Lauretta; Carley, David W

2014-01-15

To determine the effects of dronabinol on quantitative electroencephalogram (EEG) markers of the sleep process, including power distribution and ultradian cycling in 15 patients with obstructive sleep apnea (OSA). EEG (C4-A1) relative power (% total) in the delta, theta, alpha, and sigma bands was quantified by fast Fourier transformation (FFT) over 28-second intervals. An activation ratio (AR = [alpha + sigma] / [delta + theta]) also was computed for each interval. To assess ultradian rhythms, the best-fitting cosine wave was determined for AR and each frequency band in each polysomnogram (PSG). Fifteen subjects were included in the analysis. Dronabinol was associated with significantly increased theta power (p = 0.002). During the first half of the night, dronabinol decreased sigma power (p = 0.03) and AR (p = 0.03), and increased theta power (p = 0.0006). At increasing dronabinol doses, ultradian rhythms accounted for a greater fraction of EEG power variance in the delta band (p = 0.04) and AR (p = 0.03). Females had higher amplitude ultradian rhythms than males (theta: p = 0.01; sigma: p = 0.01). Decreasing AHI was associated with increasing ultradian rhythm amplitudes (sigma: p < 0.001; AR: p = 0.02). At the end of treatment, lower relative power in the theta band (p = 0.02) and lower AHI (p = 0.05) correlated with a greater decrease in sleepiness from baseline. This exploratory study demonstrates that in individuals with OSA, dronabinol treatment may yield a shift in EEG power toward delta and theta frequencies and a strengthening of ultradian rhythms in the sleep EEG.

[Clinical and neurophysiological data of neurofeedback therapy in children with ADHD].

PubMed

Kubik, Alicja; Kubik, Paweł; Stanios, Martyna; Kraj, Bogusława

2016-01-01

ADHD occurs in 3% of school-age children (and in 70% of them in adulthood) and represents an important medical and social problem. It is characterized by attention deficits, hyperactivity and impulsiveness. Neurofeedback therapy (EEG biofeedback, NF) is carried out based on the analysis of EEG. To investigate the effect of NF therapy on clinical status and parameters of the EEG in ADHD. In the years 2007-2014, 287 children (191 boys), aged 6-17 years were included into the study. Some children with ADHD had other coexisting disorders like: tics, dyslexia, emotional or behavior disorders. Visual analysis of EEG was made and 7 selected parameters of bioelectrical activity were assessed. EEG tracing before and after NF therapy were compared. NF therapy lasted from 9 months to 3 years (mean 1.5 years). 60-240 NF training sessions were performed with the use of NF device, video-games and 16-channel Elmiko devices. Statistical analysis of the results was made. Children with ADHD additionally presented low self-esteem, anxiety and sleep disorders. The baseline theta/beta ratio in children with ADHD and ADHD with cooccurring dyslexia was >4.0 and in children with ADHD and coexisting tics 3.0-3.8, with coexisting behavioral disorders 3.7-4.0 and emotional disorders 3.3-3.7. After therapy, this ratio decreased significantly in all groups, but most significantly in ADHD and ADHD with dyslexia group. In the group with dyslexia theta and alpha activity in the left fronto-temporo-parietal region (the speech centers) has been increased. In children with ADHD and behavior disorders right-sided paroxysmal changes in the form of slow and sharp waves in the temporo-centro-parietal regions were found. In emotionally disturbed children increased fast beta activity in the right hemisphere (anxiety, fear) was observed. Initially NF therapy reduced hyperactivity and impulsivity of children, subsequently improvement of attention was observed and eventually reduction of emotional and behavior disturbances was noticed. Noticeable improvement in the self-esteem was observed as well. The therapy had a positive impact on the spatial organization of EEG in each group. It proved to be particularly useful in children with ADHD and dyslexia. Neurofeedback therapy is a valuable tool with beneficial impact on children with ADHD and accompanying disorders. Characteristics of brain bioelectric activity provides a reliable basis to establish individual EEG bio-feedback protocols of therapy in children and monitor the effectiveness of treatment. In the last 4 years the number of children with ADHD and cooccurring tics who applied for neurofeedback therapy has increased significantly.

Clinical and electrographic features of sunflower syndrome.

PubMed

Baumer, Fiona M; Porter, Brenda E

2018-05-01

Sunflower Syndrome describes reflex seizures - typically eyelid myoclonia with or without absence seizures - triggered when patients wave their hands in front of the sun. While valproate has been recognized as the best treatment for photosensitive epilepsy, many clinicians now initially treat with newer medications; the efficacy of these medications in Sunflower Syndrome has not been investigated. We reviewed all cases of Sunflower Syndrome seen at our institution over 15 years to describe the clinical course, electroencephalogram (EEG), and treatment response in these patients. Search of the electronic medical record and EEG database, as well as survey of epilepsy providers at our institution, yielded 13 cases of Sunflower Syndrome between 2002 and 2017. We reviewed the records and EEG tracings. Patients were mostly young females, with an average age of onset of 5.5 years. Seven had intellectual, attentional or academic problems. Self-induced seizures were predominantly eyelid myoclonia ± absences and 6 subjects also had spontaneous seizures. EEG demonstrated a normal background with 3-4 Hz spike waves ± polyspike waves as well as a photoparoxysmal response. Based on both clinical and EEG response, valproate was the most effective treatment for reducing or eliminating seizures and improving the EEG; 9 patients tried valproate and 66% had significant improvement or resolution of seizures. None of the nine patients on levetiracetam or seven patients on lamotrigine monotherapy achieved seizure control, though three patients had improvement with polypharmacy. Valproate monotherapy continues to be the most effective treatment for Sunflower Syndrome and should be considered early. For patients who cannot tolerate valproate, higher doses of lamotrigine or polypharmacy should be considered. Levetiracetam monotherapy, even at high doses, is unlikely to be effective. Copyright © 2018 Elsevier B.V. All rights reserved.

Differential Effects of Sodium Oxybate and Baclofen on EEG, Sleep, Neurobehavioral Performance, and Memory

PubMed Central

Vienne, Julie; Lecciso, Gianpaolo; Constantinescu, Irina; Schwartz, Sophie; Franken, Paul; Heinzer, Raphaël; Tafti, Mehdi

2012-01-01

Study Objectives: Sodium oxybate (SO) is a GABAB agonist used to treat the sleep disorder narcolepsy. SO was shown to increase slow wave sleep (SWS) and EEG delta power (0.75-4.5 Hz), both indexes of NREM sleep (NREMS) intensity and depth, suggesting that SO enhances recuperative function of NREM. We investigated whether SO induces physiological deep sleep. Design: SO was administered before an afternoon nap or before the subsequent experimental night in 13 healthy volunteers. The effects of SO were compared to baclofen (BAC), another GABAB receptor agonist, to assess the role of GABAB receptors in the SO response. Measurements and Results: As expected, a nap significantly decreased sleep need and intensity the subsequent night. Both drugs reversed this nap effect on the subsequent night by decreasing sleep latency and increasing total sleep time, SWS during the first NREMS episode, and EEG delta and theta (0.75-7.25 Hz) power during NREMS. The SO-induced increase in EEG delta and theta power was, however, not specific to NREMS and was also observed during REM sleep (REMS) and wakefulness. Moreover, the high levels of delta power during a nap following SO administration did not affect delta power the following night. SO and BAC taken before the nap did not improve subsequent psychomotor performance and subjective alertness, or memory consolidation. Finally, SO and BAC strongly promoted the appearance of sleep onset REM periods. Conclusions: The SO-induced EEG slow waves seem not to be functionally similar to physiological slow waves. Our findings also suggest a role for GABAB receptors in REMS generation. Citation: Vienne J; Lecciso G; Constantinescu I; Schwartz S; Franken P; Heinzer R; Tafti M. Differential effects of sodium oxybate and baclofen on EEG, sleep, neurobehavioral performance, and memory. SLEEP 2012;35(8):1071–1084. PMID:22851803

Electroencephalographic field influence on calcium momentum waves.

PubMed

Ingber, Lester; Pappalepore, Marco; Stesiak, Ronald R

2014-02-21

Macroscopic electroencephalographic (EEG) fields can be an explicit top-down neocortical mechanism that directly drives bottom-up processes that describe memory, attention, and other neuronal processes. The top-down mechanism considered is macrocolumnar EEG firings in neocortex, as described by a statistical mechanics of neocortical interactions (SMNI), developed as a magnetic vector potential A. The bottom-up process considered is Ca(2+) waves prominent in synaptic and extracellular processes that are considered to greatly influence neuronal firings. Here, the complimentary effects are considered, i.e., the influence of A on Ca(2+) momentum, p. The canonical momentum of a charged particle in an electromagnetic field, Π=p+qA (SI units), is calculated, where the charge of Ca(2+) is q=-2e, e is the magnitude of the charge of an electron. Calculations demonstrate that macroscopic EEG A can be quite influential on the momentum p of Ca(2+) ions, in both classical and quantum mechanics. Molecular scales of Ca(2+) wave dynamics are coupled with A fields developed at macroscopic regional scales measured by coherent neuronal firing activity measured by scalp EEG. The project has three main aspects: fitting A models to EEG data as reported here, building tripartite models to develop A models, and studying long coherence times of Ca(2+) waves in the presence of A due to coherent neuronal firings measured by scalp EEG. The SMNI model supports a mechanism wherein the p+qA interaction at tripartite synapses, via a dynamic centering mechanism (DCM) to control background synaptic activity, acts to maintain short-term memory (STM) during states of selective attention. © 2013 Published by Elsevier Ltd. All rights reserved.

Scalp and Source Power Topography in Sleepwalking and Sleep Terrors: A High-Density EEG Study

PubMed Central

Castelnovo, Anna; Riedner, Brady A.; Smith, Richard F.; Tononi, Giulio; Boly, Melanie; Benca, Ruth M.

2016-01-01

Study Objectives: To examine scalp and source power topography in sleep arousals disorders (SADs) using high-density EEG (hdEEG). Methods: Fifteen adult subjects with sleep arousal disorders (SADs) and 15 age- and gender-matched good sleeping healthy controls were recorded in a sleep laboratory setting using a 256 channel EEG system. Results: Scalp EEG analysis of all night NREM sleep revealed a localized decrease in slow wave activity (SWA) power (1–4 Hz) over centro-parietal regions relative to the rest of the brain in SADs compared to good sleeping healthy controls. Source modelling analysis of 5-minute segments taken from N3 during the first half of the night revealed that the local decrease in SWA power was prominent at the level of the cingulate, motor, and sensori-motor associative cortices. Similar patterns were also evident during REM sleep and wake. These differences in local sleep were present in the absence of any detectable clinical or electrophysiological sign of arousal. Conclusions: Overall, results suggest the presence of local sleep differences in the brain of SADs patients during nights without clinical episodes. The persistence of similar topographical changes in local EEG power during REM sleep and wakefulness points to trait-like functional changes that cross the boundaries of NREM sleep. The regions identified by source imaging are consistent with the current neurophysiological understanding of SADs as a disorder caused by local arousals in motor and cingulate cortices. Persistent localized changes in neuronal excitability may predispose affected subjects to clinical episodes. Citation: Castelnovo A, Riedner BA, Smith RF, Tononi G, Boly M, Benca RM. Scalp and source power topography in sleepwalking and sleep terrors: a high-density EEG study. SLEEP 2016;39(10):1815–1825. PMID:27568805

Super-refractory nonconvulsive status epilepticus secondary to fat embolism: A clinical, electrophysiological, and pathological study.

PubMed

Fernández-Torre, José L; Burgueño, Paula; Ballesteros, María A; Hernández-Hernández, Miguel A; Villagrá-Terán, Nuria; de Lucas, Enrique Marco

2015-08-01

Fat embolism syndrome (FES) is a rare complication of long-bone fractures and joint reconstruction surgery. To the best of our knowledge, we describe the clinical, electrophysiological, neuroimaging, and neuropathological features of the first case of super-refractory nonconvulsive status epilepticus (sr-NCSE) secondary to fat embolism. An 82-year-old woman was transferred to our intensive care unit because of a sudden decrease of consciousness level, right hemiparesis, and acute respiratory failure in the early postoperative period of knee prosthesis surgery. Brain computed tomography (TC) including angio-CT and CT perfusion was normal. An urgent video-electroencephalography (v-EEG) evaluation showed continuous sharp-and slow-wave at 2.0-2.5 Hz in keeping with the diagnosis of generalized NCSE. Epileptiform discharges ceased after the administration of 5mg of intravenous diazepam, and background activity constituted by diffuse theta waves was observed without clinical improvement. Treatment with levetiracetam (1000 mg/day) and sedation with propofol and midazolam were initiated. Moreover, continuous v-EEG monitoring was also started. Despite antiepileptic therapy, epileptiform activity recurred after the interruption of profound sedation, and valproate and lacosamide were added during the ensuing days. Magnetic resonance imaging (MRI) disclosed small scattered foci of acute ischemic infarcts and diffuse petechiae involving the basal ganglia and pons and centrum semiovale in keeping with fat embolism. Super-refractory nonconvulsive status epilepticus remained without control for 2 weeks. Finally, the patient died. The clinical autopsy revealed a bilateral lung fat embolism associated with a hemorrhagic infarction in the left lower lobe. Fatty lesions were also seen in the intestine and pancreas. Scattered microscopic cerebral infarcts associated with fat emboli in the capillaries were noticed, affecting both supra- and infratentorial structures. In addition, occasional focal areas of ischemic injury showing filiform neurons with reactive astrocytic gliosis background consistent with acute lesions were observed in CA3. Fat embolism should be considered a potential cause of sr-NCSE. This article is part of a Special Issue entitled "Status Epilepticus". Copyright © 2015 Elsevier Inc. All rights reserved.

Hippocampal Sharp Wave Bursts Coincide with Neocortical "Up-State" Transitions

ERIC Educational Resources Information Center

Battaglia, Francesco P.; Sutherland, Gary R.; McNaughton, Bruce L.

2004-01-01

The sleeping neocortex shows nested oscillatory activity in different frequency ranges, characterized by fluctuations between "up-states" and "down-states." High-density neuronal ensemble recordings in rats now reveal the interaction between synchronized activity in the hippocampus and neocortex: Electroencephalographic sharp…

Lamina-specific contribution of glutamatergic and GABAergic potentials to hippocampal sharp wave-ripple complexes.

PubMed

Schönberger, Jan; Draguhn, Andreas; Both, Martin

2014-01-01

The mammalian hippocampus expresses highly organized patterns of neuronal activity which form a neuronal correlate of spatial memories. These memory-encoding neuronal ensembles form on top of different network oscillations which entrain neurons in a state- and experience-dependent manner. The mechanisms underlying activation, timing and selection of participating neurons are incompletely understood. Here we studied the synaptic mechanisms underlying one prominent network pattern called sharp wave-ripple complexes (SPW-R) which are involved in memory consolidation during sleep. We recorded SPW-R with extracellular electrodes along the different layers of area CA1 in mouse hippocampal slices. Contribution of glutamatergic excitation and GABAergic inhibition, respectively, was probed by local application of receptor antagonists into s. radiatum, pyramidale and oriens. Laminar profiles of field potentials show that GABAergic potentials contribute substantially to sharp waves and superimposed ripple oscillations in s. pyramidale. Inhibitory inputs to s. pyramidale and s. oriens are crucial for action potential timing by ripple oscillations, as revealed by multiunit-recordings in the pyramidal cell layer. Glutamatergic afferents, on the other hand, contribute to sharp waves in s. radiatum where they also evoke a fast oscillation at ~200 Hz. Surprisingly, field ripples in s. radiatum are slightly slower than ripples in s. pyramidale, resulting in a systematic shift between dendritic and somatic oscillations. This complex interplay between dendritic excitation and perisomatic inhibition may be responsible for the precise timing of discharge probability during the time course of SPW-R. Together, our data illustrate a complementary role of spatially confined excitatory and inhibitory transmission during highly ordered network patterns in the hippocampus.

Neurofeedback training aimed to improve focused attention and alertness in children with ADHD: a study of relative power of EEG rhythms using custom-made software application.

PubMed

Hillard, Brent; El-Baz, Ayman S; Sears, Lonnie; Tasman, Allan; Sokhadze, Estate M

2013-07-01

Neurofeedback is a nonpharmacological treatment for attention-deficit hyperactivity disorder (ADHD). We propose that operant conditioning of electroencephalogram (EEG) in neurofeedback training aimed to mitigate inattention and low arousal in ADHD, will be accompanied by changes in EEG bands' relative power. Patients were 18 children diagnosed with ADHD. The neurofeedback protocol ("Focus/Alertness" by Peak Achievement Trainer) has a focused attention and alertness training mode. The neurofeedback protocol provides one for Focus and one for Alertness. This does not allow for collecting information regarding changes in specific EEG bands (delta, theta, alpha, low and high beta, and gamma) power within the 2 to 45 Hz range. Quantitative EEG analysis was completed on each of twelve 25-minute-long sessions using a custom-made MatLab application to determine the relative power of each of the aforementioned EEG bands throughout each session, and from the first session to the last session. Additional statistical analysis determined significant changes in relative power within sessions (from minute 1 to minute 25) and between sessions (from session 1 to session 12). Analysis was of relative power of theta, alpha, low and high beta, theta/alpha, theta/beta, and theta/low beta and theta/high beta ratios. Additional secondary measures of patients' post-neurofeedback outcomes were assessed, using an audiovisual selective attention test (IVA + Plus) and behavioral evaluation scores from the Aberrant Behavior Checklist. Analysis of data computed in the MatLab application, determined that theta/low beta and theta/alpha ratios decreased significantly from session 1 to session 12, and from minute 1 to minute 25 within sessions. The findings regarding EEG changes resulting from brain wave self-regulation training, along with behavioral evaluations, will help elucidate neural mechanisms of neurofeedback aimed to improve focused attention and alertness in ADHD.

Opioid system of the brain and ethanol.

PubMed

Gogichadze, M; Mgaloblishvili-Nemsadze, M; Oniani, N; Emukhvary, N; Basishvili, T

2009-04-01

Influence of blocking of opioid receptors with concomitant intraperitoneal injections of Naloxone (20 mg/kg) (non-selective antagonist of opioid system) on the outcomes of anesthetic dose of ethanol (4,25 ml /kg 25% solution) was investigated in the rats. The sleep-wakefulness cycle (SWC) was used as a model for identification of the effects. Alterations of the SWC structure adequately reflect the neuro-chemical changes, which may develop during pharmacological and non-pharmacological impact. Administration of anesthetic dose of ethanol evoked considerable modification of spontaneous EEG activity of the neocortex. The EEG activity was depressed and full inhibition of spinal reflexes and somatic muscular relaxation did occur. During EEG depression regular SWC did not develop. All phases of SWC were reduced. The disturbances of SWC, such as decrease of slow wave sleep and paradoxical sleep duration and increase of wakefulness, remained for several days. At concomitant administration of Naloxone and ethanol, duration of EEG depression decreased significantly. Generation of normal SWC was observed on the same experimental day. However, it should be noted that complete abolishment of ethanol effects by Naloxone was not observed. The results obtained suggest that Naloxone partially blocks ethanol depressogenic effects and duration of this effect is mediated by GABA-ergic system of the brain.

Cortical activity during cued picture naming predicts individual differences in stuttering frequency

PubMed Central

Mock, Jeffrey R.; Foundas, Anne L.; Golob, Edward J.

2016-01-01

Objective Developmental stuttering is characterized by fluent speech punctuated by stuttering events, the frequency of which varies among individuals and contexts. Most stuttering events occur at the beginning of an utterance, suggesting neural dynamics associated with stuttering may be evident during speech preparation. Methods This study used EEG to measure cortical activity during speech preparation in men who stutter, and compared the EEG measures to individual differences in stuttering rate as well as to a fluent control group. Each trial contained a cue followed by an acoustic probe at one of two onset times (early or late), and then a picture. There were two conditions: a speech condition where cues induced speech preparation of the picture’s name and a control condition that minimized speech preparation. Results Across conditions stuttering frequency correlated to cue-related EEG beta power and auditory ERP slow waves from early onset acoustic probes. Conclusions The findings reveal two new cortical markers of stuttering frequency that were present in both conditions, manifest at different times, are elicited by different stimuli (visual cue, auditory probe), and have different EEG responses (beta power, ERP slow wave). Significance The cue-target paradigm evoked brain responses that correlated to pre-experimental stuttering rate. PMID:27472545

Long term impairment of cognitive functions and alterations of NMDAR subunits after continuous microwave exposure.

PubMed

Wang, Hui; Tan, Shengzhi; Xu, Xinping; Zhao, Li; Zhang, Jing; Yao, Binwei; Gao, Yabing; Zhou, Hongmei; Peng, Ruiyun

2017-11-01

The long term effects of continuous microwave exposure cannot be ignored for the simulation of the real environment and increasing concerns about the negative cognitive effects of microwave exposure. In this study, 220 male Wistar rats were exposed by a 2.856GHz radiation source with the average power density of 0, 2.5, 5 and 10mW/cm 2 for 6min/day, 5days/week and up to 6weeks. The MWM task, the EEG analysis, the hippocampus structure observation and the western blot were applied until the 12months after microwave exposure to detect the spatial learning and memory abilities, the cortical electrical activity, changes of hippocampal structure and the NMDAR subunits expressions. Results found that the rats in the 10mW/cm 2 group showed the decline of spatial learning and memory abilities and EEG disorders (the decrease of EEG frequencies, and increase of EEG amplitudes and delta wave powers). Moreover, changes of basic structure and ultrastructure of hippocampus also found in the 10 and 5mW/cm 2 groups. The decrease of NR 2A, 2B and p-NR2B might contribute to the impairment of cognitive functions. Our findings suggested that the continuous microwave exposure could cause the dose-dependent long term impairment of spatial learning and memory, the abnormalities of EEG and the hippocampal structure injuries. The decrease of NMDAR key subunits and phosphorylation of NR 2B might contribute to the cognitive impairment. Copyright © 2017 Elsevier Inc. All rights reserved.

Increased Alpha (8-12 Hz) Activity during Slow Wave Sleep as a Marker for the Transition from Implicit Knowledge to Explicit Insight

ERIC Educational Resources Information Center

Yordanova, Juliana; Kolev, Vasil; Wagner, Ullrich; Born, Jan; Verleger, Rolf

2012-01-01

The number reduction task (NRT) allows us to study the transition from implicit knowledge of hidden task regularities to explicit insight into these regularities. To identify sleep-associated neurophysiological indicators of this restructuring of knowledge representations, we measured frequency-specific power of EEG while participants slept during…

Cortical activity during cued picture naming predicts individual differences in stuttering frequency.

PubMed

Mock, Jeffrey R; Foundas, Anne L; Golob, Edward J

2016-09-01

Developmental stuttering is characterized by fluent speech punctuated by stuttering events, the frequency of which varies among individuals and contexts. Most stuttering events occur at the beginning of an utterance, suggesting neural dynamics associated with stuttering may be evident during speech preparation. This study used EEG to measure cortical activity during speech preparation in men who stutter, and compared the EEG measures to individual differences in stuttering rate as well as to a fluent control group. Each trial contained a cue followed by an acoustic probe at one of two onset times (early or late), and then a picture. There were two conditions: a speech condition where cues induced speech preparation of the picture's name and a control condition that minimized speech preparation. Across conditions stuttering frequency correlated to cue-related EEG beta power and auditory ERP slow waves from early onset acoustic probes. The findings reveal two new cortical markers of stuttering frequency that were present in both conditions, manifest at different times, are elicited by different stimuli (visual cue, auditory probe), and have different EEG responses (beta power, ERP slow wave). The cue-target paradigm evoked brain responses that correlated to pre-experimental stuttering rate. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Substance P and the neurokinin-1 receptor regulate electroencephalogram non-rapid eye movement sleep slow-wave activity locally

PubMed Central

Zielinski, Mark R.; Karpova, Svetlana A.; Yang, Xiaomei; Gerashchenko, Dmitry

2014-01-01

The neuropeptide substance P is an excitatory neurotransmitter produced by various cells including neurons and microglia that is involved in regulating inflammation and cerebral blood flow—functions that affect sleep and slow-wave activity (SWA). Substance P is the major ligand for the neurokinin-1 receptor (NK-1R), which is found throughout the brain including the cortex. The NK-1R is found on sleep-active cortical neurons expressing neuronal nitric oxide synthase whose activity is associated with SWA. We determined the effects of local cortical administration of a NK-1R agonist (substance P-fragment 1, 7) and a NK-1R antagonist (CP96345) on sleep and SWA in mice. The NK-1R agonist significantly enhanced SWA for several hours when applied locally to the cortex of the ipsilateral hemisphere as the electroencephalogram (EEG) electrode but not after application to the contralateral hemisphere when compared to saline vehicle control injections. In addition, a significant compensatory reduction in SWA was found after the NK-1R agonist-induced enhancements in SWA. Conversely, injections of the NK-1R antagonist into the cortex of the ipsilateral hemisphere of the EEG electrode attenuated SWA compared to vehicle injections but this effect was not found after injections of the NK-1R antagonist into contralateral hemisphere as the EEG electrode. Non-rapid eye movement sleep and rapid eye movement sleep duration responses after NK-1R agonist and antagonist injections were not significantly different from the responses to the vehicle. Our findings indicate that the substance P and the NK-1R are involved in regulating SWA locally. PMID:25301750

Choline-mediated modulation of hippocampal sharp wave-ripple complexes in vitro.

PubMed

Fischer, Viktoria; Both, Martin; Draguhn, Andreas; Egorov, Alexei V

2014-06-01

The cholinergic system is critically involved in the modulation of cognitive functions, including learning and memory. Acetylcholine acts through muscarinic (mAChRs) and nicotinic receptors (nAChRs), which are both abundantly expressed in the hippocampus. Previous evidence indicates that choline, the precursor and degradation product of Acetylcholine, can itself activate nAChRs and thereby affects intrinsic and synaptic neuronal functions. Here, we asked whether the cellular actions of choline directly affect hippocampal network activity. Using mouse hippocampal slices we found that choline efficiently suppresses spontaneously occurring sharp wave-ripple complexes (SPW-R) and can induce gamma oscillations. In addition, choline reduces synaptic transmission between hippocampal subfields CA3 and CA1. Surprisingly, these effects are mediated by activation of both mAChRs and α7-containing nAChRs. Most nicotinic effects became only apparent after local, fast application of choline, indicating rapid desensitization kinetics of nAChRs. Effects were still present following block of choline uptake and are, therefore, likely because of direct actions of choline at the respective receptors. Together, choline turns out to be a potent regulator of patterned network activity within the hippocampus. These actions may be of importance for understanding state transitions in normal and pathologically altered neuronal networks. In this study we asked whether choline, the precursor and degradation product of acetylcholine, directly affects hippocampal network activity. Using mouse hippocampal slices we found that choline efficiently suppresses spontaneously occurring sharp wave-ripple complexes (SPW-R). In addition, choline reduces synaptic transmission between hippocampal subfields. These effects are mediated by direct activation of muscarinic as well as nicotinic cholinergic pathways. Together, choline turns out to be a potent regulator of patterned activity within hippocampal networks. © 2014 International Society for Neurochemistry.

Gravity Wave Interactions with Fine Structures in the Mesosphere and Lower Thermosphere

NASA Astrophysics Data System (ADS)

Mixa, Tyler; Fritts, David; Bossert, Katrina; Laughman, Brian; Wang, Ling; Lund, Thomas; Kantha, Lakshmi

2017-04-01

An anelastic numerical model is used to probe the influences of fine layering structures on gravity wave propagation in the Mesosphere and Lower Thermosphere (MLT). Recent lidar observations confirm the presence of persistent layered structures in the MLT that have sharp stratification and vertical scales below 1km. Gravity waves propagating through finely layered environments can excite and modulate the evolution of small scale instabilities that redefine the layering structure in these regions. Such layers in turn filter the outgoing wave spectra, promote ducting or reflection, hasten the onset of self-acceleration dynamics, and encourage wave/mean-flow interactions via energy and momentum transport. Using high resolution simulations of a localized gravity wave packet in a deep atmosphere, we identify the relative impacts of various wave and mean flow parameters to improve our understanding of these dynamics and complement recent state-of-the-art observations.

Electron plasma oscillations in the Venus foreshock

NASA Technical Reports Server (NTRS)

Crawford, G. K.; Strangeway, R. J.; Russell, C. T.

1990-01-01

Plasma waves are observed in the solar wind upstream of the Venus bow shock by the Pioneer Venus Orbiter. These wave signatures occur during periods when the interplanetary magnetic field through the spacecraft position intersects the bow shock, thereby placing the spacecraft in the foreshock region. The electron foreshock boundary is clearly evident in the data as a sharp onset in wave activity and a peak in intensity. Wave intensity is seen to drop rapidly with increasing penetration into the foreshock. The peak wave electric field strength at the electron foreshock boundary is found to be similar to terrestrial observations. A normalized wave spectrum was constructed using measurements of the electron plasma frequency and the spectrum was found to be centered about this value. These results, along with polarization studies showing the wave electric field to be field aligned, are consistent with the interpretation of the waves as electron plasma oscillations.

Time course of EEG slow-wave activity in pre-school children with sleep disordered breathing: a possible mechanism for daytime deficits?

PubMed

Biggs, Sarah N; Walter, Lisa M; Nisbet, Lauren C; Jackman, Angela R; Anderson, Vicki; Nixon, Gillian M; Davey, Margot J; Trinder, John; Hoffmann, Robert; Armitage, Roseanne; Horne, Rosemary S C

2012-09-01

Daytime deficits in children with sleep disordered breathing (SDB) are theorized to result from hypoxic insult to the developing brain or fragmented sleep. Yet, these do not explain why deficits occur in primary snorers (PS). The time course of slow wave EEG activity (SWA), a proxy of homeostatic regulation and cortical maturation, may provide insight. Clinical and control subjects (N=175: mean age 4.3±0.9 y: 61% male) participated in overnight polysomnography (PSG). Standard sleep scoring and power spectral analyses were conducted on EEG (C4/A1; 0.5-<3.9Hz). Univariate ANOVA's evaluated group differences in sleep stages and respiratory parameters. Repeated-measures ANCOVA evaluated group differences in the time course of SWA. Four groups were classified: controls (OAHI ≤ 1 event/h; no clinical history); PS (OAHI ≤ 1 event/h; clinical history); mild OSA (OAHI=1-5 events/h); and moderate to severe OSA (MS OSA: OAHI>5 events/h). Group differences were found in the percentage of time spent in NREM Stages 1 and 4 (p<0.001) and in the time course of SWA. PS and Mild OSA children had higher SWA in the first NREM period than controls (p<0.05). All SDB groups had higher SWA in the fourth NREM period (p<0.01). These results suggest enhanced sleep pressure but impaired restorative sleep function in pre-school children with SDB, providing new insights into the possible mechanism for daytime deficits observed in all severities of SDB. Copyright © 2012 Elsevier B.V. All rights reserved.

Sharp wave ripples during learning stabilize hippocampal spatial map

PubMed Central

Roux, Lisa; Hu, Bo; Eichler, Ronny; Stark, Eran; Buzsáki, György

2017-01-01

Cognitive representation of the environment requires a stable hippocampal map but the mechanisms maintaining map representation are unknown. Because sharp wave-ripples (SPW-R) orchestrate both retrospective and prospective spatial information, we hypothesized that disrupting neuronal activity during SPW-Rs affects spatial representation. Mice learned daily a new set of three goal locations on a multi-well maze. We used closed-loop SPW-R detection at goal locations to trigger optogenetic silencing of a subset of CA1 pyramidal neurons. Control place cells (non-silenced or silenced outside SPW-Rs) largely maintained the location of their place fields after learning and showed increased spatial information content. In contrast, the place fields of SPW-R-silenced place cells remapped, and their spatial information remained unaltered. SPW-R silencing did not impact the firing rates or the proportions of place cells. These results suggest that interference with SPW-R-associated activity during learning prevents the stabilization and refinement of the hippocampal map. PMID:28394323

The Nature and Process of Development in Averaged Visually Evoked Potentials: Discussion on Pattern Structure.

ERIC Educational Resources Information Center

Izawa, Shuji; Mizutani, Tohru

This paper examines the development of visually evoked EEG patterns in retarded and normal subjects. The paper focuses on the averaged visually evoked potentials (AVEP) in the central and occipital regions of the brain in eyes closed and eyes open conditions. Wave pattern, amplitude, and latency are examined. The first section of the paper reviews…

Can the Brain Be Trained? Comparing the Literature on the Use of EEG Biofeedback/Neurofeedback as an Alternative or Complementary Therapy for Attention Deficit Hyperactivity Disorder (ADHD)

ERIC Educational Resources Information Center

Stankus, Tony

2008-01-01

Psychologists, social workers, and school counselors are increasingly adding neurofeedback (NFT), a controversial alternative or complementary therapy to their treatment plans for patients with Attention Deficit Hyperactivity Disorder. NFT involves training the patient in self-regulation of brain wave patterns, employing a standard diagnostic…

Diversity of sharp-wave-ripple LFP signatures reveals differentiated brain-wide dynamical events.

PubMed

Ramirez-Villegas, Juan F; Logothetis, Nikos K; Besserve, Michel

2015-11-17

Sharp-wave-ripple (SPW-R) complexes are believed to mediate memory reactivation, transfer, and consolidation. However, their underlying neuronal dynamics at multiple scales remains poorly understood. Using concurrent hippocampal local field potential (LFP) recordings and functional MRI (fMRI), we study local changes in neuronal activity during SPW-R episodes and their brain-wide correlates. Analysis of the temporal alignment between SPW and ripple components reveals well-differentiated SPW-R subtypes in the CA1 LFP. SPW-R-triggered fMRI maps show that ripples aligned to the positive peak of their SPWs have enhanced neocortical metabolic up-regulation. In contrast, ripples occurring at the trough of their SPWs relate to weaker neocortical up-regulation and absent subcortical down-regulation, indicating differentiated involvement of neuromodulatory pathways in the ripple phenomenon mediated by long-range interactions. To our knowledge, this study provides the first evidence for the existence of SPW-R subtypes with differentiated CA1 activity and metabolic correlates in related brain areas, possibly serving different memory functions.

Scalp and Source Power Topography in Sleepwalking and Sleep Terrors: A High-Density EEG Study.

PubMed

Castelnovo, Anna; Riedner, Brady A; Smith, Richard F; Tononi, Giulio; Boly, Melanie; Benca, Ruth M

2016-10-01

To examine scalp and source power topography in sleep arousals disorders (SADs) using high-density EEG (hdEEG). Fifteen adult subjects with sleep arousal disorders (SADs) and 15 age- and gender-matched good sleeping healthy controls were recorded in a sleep laboratory setting using a 256 channel EEG system. Scalp EEG analysis of all night NREM sleep revealed a localized decrease in slow wave activity (SWA) power (1-4 Hz) over centro-parietal regions relative to the rest of the brain in SADs compared to good sleeping healthy controls. Source modelling analysis of 5-minute segments taken from N3 during the first half of the night revealed that the local decrease in SWA power was prominent at the level of the cingulate, motor, and sensori-motor associative cortices. Similar patterns were also evident during REM sleep and wake. These differences in local sleep were present in the absence of any detectable clinical or electrophysiological sign of arousal. Overall, results suggest the presence of local sleep differences in the brain of SADs patients during nights without clinical episodes. The persistence of similar topographical changes in local EEG power during REM sleep and wakefulness points to trait-like functional changes that cross the boundaries of NREM sleep. The regions identified by source imaging are consistent with the current neurophysiological understanding of SADs as a disorder caused by local arousals in motor and cingulate cortices. Persistent localized changes in neuronal excitability may predispose affected subjects to clinical episodes. © 2016 Associated Professional Sleep Societies, LLC.

Differential effects of sodium oxybate and baclofen on EEG, sleep, neurobehavioral performance, and memory.

PubMed

Vienne, Julie; Lecciso, Gianpaolo; Constantinescu, Irina; Schwartz, Sophie; Franken, Paul; Heinzer, Raphaël; Tafti, Mehdi

2012-08-01

Sodium oxybate (SO) is a GABAβ agonist used to treat the sleep disorder narcolepsy. SO was shown to increase slow wave sleep (SWS) and EEG delta power (0.75-4.5 Hz), both indexes of NREM sleep (NREMS) intensity and depth, suggesting that SO enhances recuperative function of NREM. We investigated whether SO induces physiological deep sleep. SO was administered before an afternoon nap or before the subsequent experimental night in 13 healthy volunteers. The effects of SO were compared to baclofen (BAC), another GABAβ receptor agonist, to assess the role of GABAβ receptors in the SO response. As expected, a nap significantly decreased sleep need and intensity the subsequent night. Both drugs reversed this nap effect on the subsequent night by decreasing sleep latency and increasing total sleep time, SWS during the first NREMS episode, and EEG delta and theta (0.75-7.25 Hz) power during NREMS. The SO-induced increase in EEG delta and theta power was, however, not specific to NREMS and was also observed during REM sleep (REMS) and wakefulness. Moreover, the high levels of delta power during a nap following SO administration did not affect delta power the following night. SO and BAC taken before the nap did not improve subsequent psychomotor performance and subjective alertness, or memory consolidation. Finally, SO and BAC strongly promoted the appearance of sleep onset REM periods. The SO-induced EEG slow waves seem not to be functionally similar to physiological slow waves. Our findings also suggest a role for GABAβ receptors in REMS generation.

Interobserver variability in recognizing arousal in respiratory sleep disorders.

PubMed

Drinnan, M J; Murray, A; Griffiths, C J; Gibson, G J

1998-08-01

Daytime sleepiness is a common consequence of repeated arousal in obstructive sleep apnea (OSA). Arousal indices are sometimes used to make decisions on treatment, but there is no evidence that arousals are detected similarly even by experienced observers. Using the American Sleep Disorders Association (ASDA) definition of arousal in terms of the accompanying electroencephalogram (EEG) changes, we have quantified interobserver agreement for arousal scoring and identified factors affecting it. Ten patients with suspected OSA were studied; three representative EEG events during each of light, slow-wave, and rapid-eye-movement (REM) sleep were extracted from each record (90 events total) and evaluated by experts in 14 sleep laboratories. Observers differed (ANOVA, p < 0.001) in the number of events scored as arousal (totals ranged from 23 to 53 of the 90 events). Overall agreement was moderate (kappa = 0.47), but it was best for events during slow-wave sleep, moderate for REM, and poor for light sleep (kappa = 0.60, 0.52, and 0.28, respectively). Agreement was unrelated to arousal duration. We conclude that the ASDA definition of arousal is only moderately repeatable. Account should be taken of this variability when results from different centers are compared.

Dentate network activity is necessary for spatial working memory by supporting CA3 sharp-wave ripple generation and prospective firing of CA3 neurons.

PubMed

Sasaki, Takuya; Piatti, Verónica C; Hwaun, Ernie; Ahmadi, Siavash; Lisman, John E; Leutgeb, Stefan; Leutgeb, Jill K

2018-02-01

Complex spatial working memory tasks have been shown to require both hippocampal sharp-wave ripple (SWR) activity and dentate gyrus (DG) neuronal activity. We therefore asked whether DG inputs to CA3 contribute to spatial working memory by promoting SWR generation. Recordings from DG and CA3 while rats performed a dentate-dependent working memory task on an eight-arm radial maze revealed that the activity of dentate neurons and the incidence rate of SWRs both increased during reward consumption. We then found reduced reward-related CA3 SWR generation without direct input from dentate granule neurons. Furthermore, CA3 cells with place fields in not-yet-visited arms preferentially fired during SWRs at reward locations, and these prospective CA3 firing patterns were more pronounced for correct trials and were dentate-dependent. These results indicate that coordination of CA3 neuronal activity patterns by DG is necessary for the generation of neuronal firing patterns that support goal-directed behavior and memory.

Interplay between Hippocampal Sharp-Wave-Ripple Events and Vicarious Trial and Error Behaviors in Decision Making.

PubMed

Papale, Andrew E; Zielinski, Mark C; Frank, Loren M; Jadhav, Shantanu P; Redish, A David

2016-12-07

Current theories posit that memories encoded during experiences are subsequently consolidated into longer-term storage. Hippocampal sharp-wave-ripple (SWR) events have been linked to this consolidation process during sleep, but SWRs also occur during awake immobility, where their role remains unclear. We report that awake SWR rates at the reward site are inversely related to the prevalence of vicarious trial and error (VTE) behaviors, thought to be involved in deliberation processes. SWR rates were diminished immediately after VTE behaviors and an increase in the rate of SWR events at the reward site predicted a decrease in subsequent VTE behaviors at the choice point. Furthermore, SWR disruptions increased VTE behaviors. These results suggest an inverse relationship between SWRs and VTE behaviors and suggest that awake SWRs and associated planning and memory consolidation mechanisms are engaged specifically in the context of higher levels of behavioral certainty. Copyright © 2016 Elsevier Inc. All rights reserved.

The EEG Split Alpha Peak: Phenomenological Origins and Methodological Aspects of Detection and Evaluation.

PubMed

Olejarczyk, Elzbieta; Bogucki, Piotr; Sobieszek, Aleksander

2017-01-01

Electroencephalographic (EEG) patterns were analyzed in a group of ambulatory patients who ranged in age and sex using spectral analysis as well as Directed Transfer Function, a method used to evaluate functional brain connectivity. We tested the impact of window size and choice of reference electrode on the identification of two or more peaks with close frequencies in the spectral power distribution, so called "split alpha." Together with the connectivity analysis, examination of spatiotemporal maps showing the distribution of amplitudes of EEG patterns allowed for better explanation of the mechanisms underlying the generation of split alpha peaks. It was demonstrated that the split alpha spectrum can be generated by two or more independent and interconnected alpha wave generators located in different regions of the cerebral cortex, but not necessarily in the occipital cortex. We also demonstrated the importance of appropriate reference electrode choice during signal recording. In addition, results obtained using the original data were compared with results obtained using re-referenced data, using average reference electrode and reference electrode standardization techniques.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenau, Philip

A wide variety of propagating disturbances in physical systems are described by equations whose solutions lack a sharp propagating front. We demonstrate that presence of particular nonlinearities may induce such fronts. To exemplify this idea, we study both dissipative u{sub t}+{partial_derivative}{sub x}f(u)=u{sub xx} and dispersive u{sub t}+{partial_derivative}{sub x}f(u)+u{sub xxx}=0 patterns, and show that a weakly singular convection f(u)=-u{sup {alpha}}+u{sup m}, 0<{alpha}<1

Ultradian rhythms in pituitary and adrenal hormones: their relations to sleep.

PubMed

Gronfier, C; Brandenberger, G

1998-02-01

Sleep and circadian rhythmicity both influence the 24-h profiles of the main pituitary and adrenal hormones. From studies using experimental strategies including complete and partial sleep deprivation, acute and chronic shifts in the sleep period, or complete sleep-wake reversal as occurs with transmeridian travel or shift-work, it appears that prolactin (PRL) and growth hormone (GH) profiles are mainly sleep related, while cortisol profile is mainly controlled by the circadian clock with a weak influence of sleep processes. Thyrotropin (TSH) profile is under the dual influence of sleep and circadian rhythmicity. Recent studies, in which we used spectral analysis of sleep electroencephalogram (EEG) rather than visual scoring of sleep stages, have evaluated the temporal associations between pulsatile hormonal release and the variations in sleep EEG activity. Pulses in PRL and in GH are positively linked to increases in delta wave activity, whereas TSH and cortisol pulses are related to decreases in delta wave activity. It is yet not clear whether sleep influences endocrine secretion, or conversely, whether hormone secretion affects sleep structure. These well-defined relationships raise the question of their physiological significance and of their clinical implications.

Development of wireless, chipless neural stimulator by using one-port surface acoustic wave delay line and diode-capacitor interface

NASA Astrophysics Data System (ADS)

Kim, Jisung; Kim, Saehan; Lee, Keekeun

2017-06-01

For the first time, a wireless and chipless neuron stimulator was developed by utilizing a surface acoustic wave (SAW) delay line, a diode-capacitor interface, a sharp metal tip, and antennas for the stimulation of neurons in the brain. The SAW delay line supersedes presently existing complex wireless transmission systems composed of a few thousands of transistors, enabling the fabrication of wireless and chipless transceiver systems. The diode-capacitor interface was used to convert AC signals to DC signals and induce stimulus pulses at a sharp metal probe. A 400 MHz RF energy was wirelessly radiated from antennas and then stimulation pulses were observed at a sharp gold probe. A ˜5 m reading distance was obtained using a 1 mW power from a network analyzer. The cycles of electromagnetic (EM) radiation from an antenna were controlled by shielding the antenna with an EM absorber. Stimulation pulses with different amplitudes and durations were successfully observed at the probe. The obtained pulses were ˜0.08 mV in amplitude and 3-10 Hz in frequency. Coupling-of-mode (COM) and SPICE modeling simulations were also used to determine the optimal structural parameters for SAW delay line and the values of passive elements. On the basis of the extracted parameters, the entire system was experimentally implemented and characterized.

Sustained increase in hippocampal sharp-wave ripple activity during slow-wave sleep after learning

PubMed Central

Eschenko, Oxana; Ramadan, Wiâm; Mölle, Matthias; Born, Jan; Sara, Susan J.

2008-01-01

High-frequency oscillations, known as sharp-wave/ripple (SPW-R) complexes occurring in hippocampus during slow-wave sleep (SWS), have been proposed to promote synaptic plasticity necessary for memory consolidation. We recorded sleep for 3 h after rats were trained on an odor-reward association task. Learning resulted in an increased number SPW-Rs during the first hour of post-learning SWS. The magnitude of ripple events and their duration were also elevated for up to 2 h after the newly formed memory. Rats that did not learn the discrimination during the training session did not show any change in SPW-Rs. Successful retrieval from remote memory was likewise accompanied by an increase in SPW-R density and magnitude, relative to the previously recorded baseline, but the effects were much shorter lasting and did not include increases in ripple duration and amplitude. A short-lasting increase of ripple activity was also observed when rats were rewarded for performing a motor component of the task only. There were no increases in ripple activity after habituation to the experimental environment. These experiments show that the characteristics of hippocampal high-frequency oscillations during SWS are affected by prior behavioral experience. Associative learning induces robust and sustained (up to 2 h) changes in several SPW-R characteristics, while after retrieval from remote memory or performance of a well-trained procedural aspect of the task, only transient changes in ripple density were induced. PMID:18385477

Insights into sleep's role for insight: Studies with the number reduction task

PubMed Central

Verleger, Rolf; Rose, Michael; Wagner, Ullrich; Yordanova, Juliana; Kolev, Vasil

2013-01-01

In recent years, vibrant research has developed on “consolidation” during sleep: To what extent are newly experienced impressions reprocessed or even restructured during sleep? We used the number reduction task (NRT) to study if and how sleep does not only reiterate new experiences but may even lead to new insights. In the NRT, covert regularities may speed responses. This implicit acquisition of regularities may become explicitly conscious at some point, leading to a qualitative change in behavior which reflects this insight. By applying the NRT at two consecutive sessions separated by an interval, we investigated the role of sleep in this interval for attaining insight at the second session. In the first study, a night of sleep was shown to triple the number of participants attaining insight above the base rate of about 20%. In the second study, this hard core of 20% discoverers differed from other participants in their task-related EEG potentials from the very beginning already. In the third study, the additional role of sleep was specified as an effect of the deep-sleep phase of slow-wave sleep on participants who had implicitly acquired the covert regularity before sleep. It was in these participants that a specific increase of EEG during slow-wave sleep in the 10-12 Hz band was obtained. These results support the view that neuronal memory reprocessing during slow-wave sleep restructures task-related representations in the brain, and that such restructuring promotes the gain of explicit knowledge. PMID:24605175

INDUCED EEG GAMMA OSCILLATION ALIGNMENT IMPROVES DIFFERENTIATION BETWEEN AUTISM AND ADHD GROUP RESPONSES IN A FACIAL CATEGORIZATION TASK

PubMed Central

Gross, Eric; El-Baz, Ayman S.; Sokhadze, Guela E.; Sears, Lonnie; Casanova, Manuel F.; Sokhadze, Estate M.

2012-01-01

Introduction Children diagnosed with an autism spectrum disorder (ASD) often lack the ability to recognize and properly respond to emotional stimuli. Emotional deficits also characterize children with attention deficit/hyperactivity disorder (ADHD), in addition to exhibiting limited attention span. These abnormalities may effect a difference in the induced EEG gamma wave burst (35–45 Hz) peaked approximately 300–400 milliseconds following an emotional stimulus. Because induced gamma oscillations are not fixed at a definite point in time post-stimulus, analysis of averaged EEG data with traditional methods may result in an attenuated gamma burst power. Methods We used a data alignment technique to improve the averaged data, making it a better representation of the individual induced EEG gamma oscillations. A study was designed to test the response of a subject to emotional stimuli, presented in the form of emotional facial expression images. In a four part experiment, the subjects were instructed to identify gender in the first two blocks of the test, followed by differentiating between basic emotions in the final two blocks (i.e. anger vs. disgust). EEG data was collected from ASD (n=10), ADHD (n=9), and control (n=11) subjects via a 128 channel EGI system, and processed through a continuous wavelet transform and bandpass filter to isolate the gamma frequencies. A custom MATLAB code was used to align the data from individual trials between 200–600 ms post-stimulus, EEG site, and condition by maximizing the Pearson product-moment correlation coefficient between trials. The gamma power for the 400 ms window of maximum induced gamma burst was then calculated and compared between subject groups. Results and Conclusion Condition (anger/disgust recognition, gender recognition) × Alignment × Group (ADHD, ASD, Controls) interaction was significant at most of parietal topographies (e.g., P3–P4, P7–P8). These interactions were better manifested in the aligned data set. Our results show that alignment of the induced gamma oscillations improves sensitivity of this measure in differentiation of EEG responses to emotional facial stimuli in ADHD and ASD. PMID:22754277

EEG Subspace Analysis and Classification Using Principal Angles for Brain-Computer Interfaces

NASA Astrophysics Data System (ADS)

Ashari, Rehab Bahaaddin

Brain-Computer Interfaces (BCIs) help paralyzed people who have lost some or all of their ability to communicate and control the outside environment from loss of voluntary muscle control. Most BCIs are based on the classification of multichannel electroencephalography (EEG) signals recorded from users as they respond to external stimuli or perform various mental activities. The classification process is fraught with difficulties caused by electrical noise, signal artifacts, and nonstationarity. One approach to reducing the effects of similar difficulties in other domains is the use of principal angles between subspaces, which has been applied mostly to video sequences. This dissertation studies and examines different ideas using principal angles and subspaces concepts. It introduces a novel mathematical approach for comparing sets of EEG signals for use in new BCI technology. The success of the presented results show that principal angles are also a useful approach to the classification of EEG signals that are recorded during a BCI typing application. In this application, the appearance of a subject's desired letter is detected by identifying a P300-wave within a one-second window of EEG following the flash of a letter. Smoothing the signals before using them is the only preprocessing step that was implemented in this study. The smoothing process based on minimizing the second derivative in time is implemented to increase the classification accuracy instead of using the bandpass filter that relies on assumptions on the frequency content of EEG. This study examines four different ways of removing outliers that are based on the principal angles and shows that the outlier removal methods did not help in the presented situations. One of the concepts that this dissertation focused on is the effect of the number of trials on the classification accuracies. The achievement of the good classification results by using a small number of trials starting from two trials only, should make this approach more appropriate for online BCI applications. In order to understand and test how EEG signals are different from one subject to another, different users are tested in this dissertation, some with motor impairments. Furthermore, the concept of transferring information between subjects is examined by training the approach on one subject and testing it on the other subject using the training subject's EEG subspaces to classify the testing subject's trials.

Evaluation of a Low-cost and Low-noise Active Dry Electrode for Long-term Biopotential Recording

PubMed Central

Pourahmad, Ali; Mahnam, Amin

2016-01-01

Wet Ag/AgCl electrodes, although very popular in clinical diagnosis, are not appropriate for expanding applications of wearable biopotential recording systems which are used repetitively and for a long time. Here, the development of a low-cost and low-noise active dry electrode is presented. The performance of the new electrodes was assessed for recording electrocardiogram (ECG) and electroencephalogram (EEG) in comparison with that of typical gel-based electrodes in a series of long-term recording experiments. The ECG signal recorded by these electrodes was well comparable with usual Ag/AgCl electrodes with a correlation up to 99.5% and mean power line noise below 6.0 μVRMS. The active electrodes were also used to measure alpha wave and steady state visual evoked potential by recording EEG. The recorded signals were comparable in quality with signals recorded by standard gel electrodes, suggesting that the designed electrodes can be employed in EEG-based rehabilitation systems and brain-computer interface applications. The mean power line noise in EEG signals recorded by the active electrodes (1.3 μVRMS) was statistically lower than when conventional gold cup electrodes were used (2.0 μVRMS) with a significant level of 0.05, and the new electrodes appeared to be more resistant to the electromagnetic interferences. These results suggest that the developed low-cost electrodes can be used to develop wearable monitoring systems for long-term biopotential recording. PMID:28028495

Processing of emotional words measured simultaneously with steady-state visually evoked potentials and near-infrared diffusing-wave spectroscopy.

PubMed

Koban, Leonie; Ninck, Markus; Li, Jun; Gisler, Thomas; Kissler, Johanna

2010-07-27

Emotional stimuli are preferentially processed compared to neutral ones. Measuring the magnetic resonance blood-oxygen level dependent (BOLD) response or EEG event-related potentials, this has also been demonstrated for emotional versus neutral words. However, it is currently unclear whether emotion effects in word processing can also be detected with other measures such as EEG steady-state visual evoked potentials (SSVEPs) or optical brain imaging techniques. In the present study, we simultaneously performed SSVEP measurements and near-infrared diffusing-wave spectroscopy (DWS), a new optical technique for the non-invasive measurement of brain function, to measure brain responses to neutral, pleasant, and unpleasant nouns flickering at a frequency of 7.5 Hz. The power of the SSVEP signal was significantly modulated by the words' emotional content at occipital electrodes, showing reduced SSVEP power during stimulation with pleasant compared to neutral nouns. By contrast, the DWS signal measured over the visual cortex showed significant differences between stimulation with flickering words and baseline periods, but no modulation in response to the words' emotional significance. This study is the first investigation of brain responses to emotional words using simultaneous measurements of SSVEPs and DWS. Emotional modulation of word processing was detected with EEG SSVEPs, but not by DWS. SSVEP power for emotional, specifically pleasant, compared to neutral words was reduced, which contrasts with previous results obtained when presenting emotional pictures. This appears to reflect processing differences between symbolic and pictorial emotional stimuli. While pictures prompt sustained perceptual processing, decoding the significance of emotional words requires more internal associative processing. Reasons for an absence of emotion effects in the DWS signal are discussed.

Physiological signal analysis for fatigue level of experienced and inexperienced drivers.

PubMed

Li, Rui; Su, Wencheng; Lu, Zhangping

2017-02-17

We studied the changes in driving fatigue levels of experienced and inexperienced drivers at 3 periods of the day: 9:00 a.m.-12:00 p.m., 12:00 p.m.-2:00 p.m., and 4:00 p.m.-6:00 p.m. Thirty drivers were involved in 120-min real-car driving, and sleepiness ratings (Stanford Sleepiness Scale, SSS; Hoddes et al. 1973 ), electroencephalogram (EEG) signals, and heart rates (HRs) were recorded. Together with principal component analysis, the relationship between EEG signals and HR was explored and used to determine a comprehensive indicator of driving fatigue. Then the comprehensive indicator was assessed via paired t test. Experienced and inexperienced drivers behaved significantly differently in terms of subjective fatigue during preliminary trials. At the beginning of trials and after termination, subjective fatigue level was aggravated with prolonged continuous driving. Moreover, we discussed the changing rules of EEG signals and HR and found that with prolonged time, the ratios of δ and β waves significantly declined, whereas that of the θ wave significantly rose. The ratio of (α + θ)/β significantly rose both before trials and after termination, but HR dropped significantly. However, one-factor analysis of variance shows that driving experience significantly affects the θ wave, (α + θ)/β ratio, and HR. We found that in a monotonous road environment, fatigue symptoms occurred in inexperienced drivers and experienced drivers after about 60 and 80 min of continuous driving, respectively. Therefore, as for drivers with different experiences, restriction on continuous driving time would avoid fatigued driving and thereby eliminate traffic accidents. We find that the comprehensive indicator changes significantly with fatigue level. The integration of different indicators improves the recognition accuracy of different driving fatigue levels.

Sustained Sleep Fragmentation Induces Sleep Homeostasis in Mice

PubMed Central

Baud, Maxime O.; Magistretti, Pierre J.; Petit, Jean-Marie

2015-01-01

Study Objectives: Sleep fragmentation (SF) is an integral feature of sleep apnea and other prevalent sleep disorders. Although the effect of repetitive arousals on cognitive performance is well documented, the effects of long-term SF on electroencephalography (EEG) and molecular markers of sleep homeostasis remain poorly investigated. To address this question, we developed a mouse model of chronic SF and characterized its effect on EEG spectral frequencies and the expression of genes previously linked to sleep homeostasis including clock genes, heat shock proteins, and plasticity-related genes. Design: N/A. Setting: Animal sleep research laboratory. Participants : Sixty-six C57BL6/J adult mice. Interventions: Instrumental sleep disruption at a rate of 60/h during 14 days Measurements and Results: Locomotor activity and EEG were recorded during 14 days of SF followed by recovery for 2 days. Despite a dramatic number of arousals and decreased sleep bout duration, SF minimally reduced total quantity of sleep and did not significantly alter its circadian distribution. Spectral analysis during SF revealed a homeostatic drive for slow wave activity (SWA; 1–4 Hz) and other frequencies as well (4–40 Hz). Recordings during recovery revealed slow wave sleep consolidation and a transient rebound in SWA, and paradoxical sleep duration. The expression of selected genes was not induced following chronic SF. Conclusions: Chronic sleep fragmentation (SF) increased sleep pressure confirming that altered quality with preserved quantity triggers core sleep homeostasis mechanisms. However, it did not induce the expression of genes induced by sleep loss, suggesting that these molecular pathways are not sustainably activated in chronic diseases involving SF. Citation: Baud MO, Magistretti PJ, Petit JM. Sustained sleep fragmentation induces sleep homeostasis in mice. SLEEP 2015;38(4):567–579. PMID:25325477

Deep sleep after social stress: NREM sleep slow-wave activity is enhanced in both winners and losers of a conflict.

PubMed

Kamphuis, Jeanine; Lancel, Marike; Koolhaas, Jaap M; Meerlo, Peter

2015-07-01

Sleep is considered to be a recovery process of prior wakefulness. Not only duration of the waking period affects sleep architecture and sleep EEG, the quality of wakefulness is also highly important. Studies in rats have shown that social defeat stress, in which experimental animals are attacked and defeated by a dominant conspecific, is followed by an acute increase in NREM sleep EEG slow wave activity (SWA). However, it is not known whether this effect is specific for the stress of social defeat or a result of the conflict per se. In the present experiment, we examined how sleep is affected in both the winners and losers of a social conflict. Sleep-wake patterns and sleep EEG were recorded in male wild-type Groningen rats that were subjected to 1h of social conflict in the middle of the light phase. All animals were confronted with a conspecific of similar aggression level and the conflict took place in a neutral arena where both individuals had an equal chance to either win or lose the conflict. NREM sleep SWA was significantly increased after the social conflict compared to baseline values and a gentle stimulation control condition. REM sleep was significantly suppressed in the first hours after the conflict. Winners and losers did not differ significantly in NREM sleep time, NREM sleep SWA and REM sleep time immediately after the conflict. Losers tended to have slightly more NREM sleep later in the recovery period. This study shows that in rats a social conflict with an unpredictable outcome has quantitatively and qualitatively largely similar acute effects on subsequent sleep in winners and losers. Copyright © 2015 Elsevier Inc. All rights reserved.

Visualization of Whole-Night Sleep EEG From 2-Channel Mobile Recording Device Reveals Distinct Deep Sleep Stages with Differential Electrodermal Activity.

PubMed

Onton, Julie A; Kang, Dae Y; Coleman, Todd P

2016-01-01

Brain activity during sleep is a powerful marker of overall health, but sleep lab testing is prohibitively expensive and only indicated for major sleep disorders. This report demonstrates that mobile 2-channel in-home electroencephalogram (EEG) recording devices provided sufficient information to detect and visualize sleep EEG. Displaying whole-night sleep EEG in a spectral display allowed for quick assessment of general sleep stability, cycle lengths, stage lengths, dominant frequencies and other indices of sleep quality. By visualizing spectral data down to 0.1 Hz, a differentiation emerged between slow-wave sleep with dominant frequency between 0.1-1 Hz or 1-3 Hz, but rarely both. Thus, we present here the new designations, Hi and Lo Deep sleep, according to the frequency range with dominant power. Simultaneously recorded electrodermal activity (EDA) was primarily associated with Lo Deep and very rarely with Hi Deep or any other stage. Therefore, Hi and Lo Deep sleep appear to be physiologically distinct states that may serve unique functions during sleep. We developed an algorithm to classify five stages (Awake, Light, Hi Deep, Lo Deep and rapid eye movement (REM)) using a Hidden Markov Model (HMM), model fitting with the expectation-maximization (EM) algorithm, and estimation of the most likely sleep state sequence by the Viterbi algorithm. The resulting automatically generated sleep hypnogram can help clinicians interpret the spectral display and help researchers computationally quantify sleep stages across participants. In conclusion, this study demonstrates the feasibility of in-home sleep EEG collection, a rapid and informative sleep report format, and novel deep sleep designations accounting for spectral and physiological differences.

Sleep Homeostatic and Waking Behavioral Phenotypes in Egr3-Deficient Mice Associated with Serotonin Receptor 5-HT2 Deficits.

PubMed

Grønli, Janne; Clegern, William C; Schmidt, Michelle A; Nemri, Rahmi S; Rempe, Michael J; Gallitano, Amelia L; Wisor, Jonathan P

2016-12-01

The expression of the immediate early gene early growth response 3 ( Egr3 ) is a functional marker of brain activity including responses to novelty, sustained wakefulness, and sleep. We examined the role of this gene in regulating wakefulness and sleep. Electroencephalogram/electromyogram (EEG/EMG) were recorded in Egr3 -/- and wild-type (WT) mice during 24 h baseline, 6 h sleep disruption and 6 h recovery. Serotonergic signaling was assessed with 6 h EEG/EMG recordings after injections of nonselective 5-HT2 antagonist (clozapine), selective 5-HT2 antagonists (5-HT2A; MDL100907 and 5-HT2BC; SB206553) and a cocktail of both selective antagonists, administered in a randomized order to each animal. Egr3 -/- mice did not exhibit abnormalities in the timing of wakefulness and slow wave sleep (SWS); however, EEG dynamics in SWS (suppressed 1-3 Hz power) and in quiet wakefulness (elevated 3-8 Hz and 15-35 Hz power) differed in comparison to WT-mice. Egr3 -/- mice showed an exaggerated response to sleep disruption as measured by active wakefulness, but with a blunted increase in homeostatic sleep drive (elevated 1-4 Hz power) relative to WT-mice. Egr3 -/-mice exhibit greatly reduced sedative effects of clozapine at the electroencephalographic level. In addition, clozapine induced a previously undescribed dissociated state (low amplitude, low frequency EEG and a stable, low muscle tone) lasting up to 2 h in WT-mice. Egr3 -/- mice did not exhibit this phenomenon. Selective 5-HT2A antagonist, alone or in combination with selective 5-HT2BC antagonist, caused EEG slowing coincident with behavioral quiescence in WT-mice but not in Egr3 -/- mice. Egr3 has an essential role in regulating cortical arousal, wakefulness, and sleep, presumably by its regulation of 5-HT2 receptors. © 2016 Associated Professional Sleep Societies, LLC.

Intra- and interregional cortical interactions related to sharp-wave ripples and dentate spikes.

PubMed

Headley, Drew B; Kanta, Vasiliki; Paré, Denis

2017-02-01

The hippocampus generates population events termed sharp-wave ripples (SWRs) and dentate spikes (DSs). While little is known about DSs, SWR-related hippocampal discharges during sleep are thought to replay prior waking activity, reactivating the cortical networks that encoded the initial experience. During slow-wave sleep, such reactivations likely occur during up-states, when most cortical neurons are depolarized. However, most studies have examined the relationship between SWRs and up-states measured in single neocortical regions. As a result, it is currently unclear whether SWRs are associated with particular patterns of widely distributed cortical activity. Additionally, no such investigation has been carried out for DSs. The present study addressed these questions by recording SWRs and DSs from the dorsal hippocampus simultaneously with prefrontal, sensory (visual and auditory), perirhinal, and entorhinal cortices in naturally sleeping rats. We found that SWRs and DSs were associated with up-states in all cortical regions. Up-states coinciding with DSs and SWRs exhibited increased unit activity, power in the gamma band, and intraregional gamma coherence. Unexpectedly, interregional gamma coherence rose much more strongly in relation to DSs than to SWRs. Whereas the increase in gamma coherence was time locked to DSs, that seen in relation to SWRs was not. These observations suggest that SWRs are related to the strength of up-state activation within individual regions throughout the neocortex but not so much to gamma coherence between different regions. Perhaps more importantly, DSs coincided with stronger periods of interregional gamma coherence, suggesting that they play a more important role than previously assumed. Off-line cortico-hippocampal interactions are thought to support memory consolidation. We surveyed the relationship between hippocampal sharp-wave ripples (SWRs) and dentate spikes (DSs) with up-states across multiple cortical regions. SWRs and DSs were associated with increased cortical gamma oscillations. Interregional gamma coherence rose much more strongly in relation to DSs than to SWRs. Moreover, it was time locked to DSs but not SWRs. These results have important implications for current theories of systems memory consolidation during sleep. Copyright © 2017 the American Physiological Society.

Effects of UGTs on the ionosphere

NASA Astrophysics Data System (ADS)

Argo, P. E.; Fitzgerald, T. J.

The processes that propagate local effects of underground nuclear tests from the ground into the upper atmosphere, and produce a detectable signal in the ionosphere are described. Initially, the blast wave from a underground test (UGT) radially expands, until it reaches the surface of the earth. The wave is both reflected and transmitted at this sharp discontinuity in propagation media. Tne reflected wave combines with the incident wave to form an 'Airy surface,' at which very strong ripping forces tear the earth apart. This broken region is called the 'spat zone,' and is launched into ballistic motion. The resultant ground motion launches an acoustical wave into the atmosphere. This acoustic wave, with overpressures of a few tenths of one percent, propagates upwards at the speed of sound. Assuming purely linear propagation, the path of the acoustic energy can be tracked using raytracing models. Most of the wave energy, which is radiated nearly vertically, tends to propagate into the upper atmosphere, while wave energy radiated at angles greater than about 30 degrees to the vertical will be reflected back to earth and is probably what is seen by most infrasonde measurements.

[Nootropics and antioxidants in the complex therapy of symptomatic posttraumatic epilepsy].

PubMed

Savenkov, A A; Badalian, O L; Avakian, G N

2013-01-01

To study the possibility of application of nootropics and antioxidants in the complex antiepileptic therapy, we examined 75 patients with symptomatic focal posttraumatic epilepsy. A statistically significant reduction in the number of epileptic seizures, improvement of cognitive function and quality of life of the patients as well as a decrease in the severity of depression and epileptic changes in the EEG were identified. The potentiation of antiepileptic activity of basic drugs, normalization of brain's electrical activity and reduction in EEG epileptiform activity, in particular coherent indicators of slow-wave activity, were noted after treatment with the antioxidant mexidol. A trend towards the improvement of neuropsychological performance and quality of life was observed. There was a lack of seizure aggravation typical of many nootropic drugs. Thus, phenotropil and mexidol can be recommended for complex treatment of symptomatic posttraumatic epilepsy.

INDUCED EEG GAMMA OSCILLATION ALIGNMENT IMPROVES DIFFERENTIATION BETWEEN AUTISM AND ADHD GROUP RESPONSES IN A FACIAL CATEGORIZATION TASK.

PubMed

Gross, Eric; El-Baz, Ayman S; Sokhadze, Guela E; Sears, Lonnie; Casanova, Manuel F; Sokhadze, Estate M

2012-01-01

INTRODUCTION: Children diagnosed with an autism spectrum disorder (ASD) often lack the ability to recognize and properly respond to emotional stimuli. Emotional deficits also characterize children with attention deficit/hyperactivity disorder (ADHD), in addition to exhibiting limited attention span. These abnormalities may effect a difference in the induced EEG gamma wave burst (35-45 Hz) peaked approximately 300-400 milliseconds following an emotional stimulus. Because induced gamma oscillations are not fixed at a definite point in time post-stimulus, analysis of averaged EEG data with traditional methods may result in an attenuated gamma burst power. METHODS: We used a data alignment technique to improve the averaged data, making it a better representation of the individual induced EEG gamma oscillations. A study was designed to test the response of a subject to emotional stimuli, presented in the form of emotional facial expression images. In a four part experiment, the subjects were instructed to identify gender in the first two blocks of the test, followed by differentiating between basic emotions in the final two blocks (i.e. anger vs. disgust). EEG data was collected from ASD (n=10), ADHD (n=9), and control (n=11) subjects via a 128 channel EGI system, and processed through a continuous wavelet transform and bandpass filter to isolate the gamma frequencies. A custom MATLAB code was used to align the data from individual trials between 200-600 ms post-stimulus, EEG site, and condition by maximizing the Pearson product-moment correlation coefficient between trials. The gamma power for the 400 ms window of maximum induced gamma burst was then calculated and compared between subject groups. RESULTS AND CONCLUSION: Condition (anger/disgust recognition, gender recognition) × Alignment × Group (ADHD, ASD, Controls) interaction was significant at most of parietal topographies (e.g., P3-P4, P7-P8). These interactions were better manifested in the aligned data set. Our results show that alignment of the induced gamma oscillations improves sensitivity of this measure in differentiation of EEG responses to emotional facial stimuli in ADHD and ASD.

The Brain and Learning: Examining the Connection between Brain Activity, Spatial Intelligence, and Learning Outcomes in Online Visual Instruction

ERIC Educational Resources Information Center

Lee, Hyangsook

2013-01-01

The purpose of the study was to compare 2D and 3D visual presentation styles, both still frame and animation, on subjects' brain activity measured by the amplitude of EEG alpha wave and on their recall to see if alpha power and recall differ significantly by depth and movement of visual presentation style and by spatial intelligence. In addition,…

Relationships between menopausal and mood symptoms and EEG sleep measures in a multi-ethnic sample of middle-aged women: the SWAN sleep study.

PubMed

Kravitz, Howard M; Avery, Elizabeth; Sowers, Maryfran; Bromberger, Joyce T; Owens, Jane F; Matthews, Karen A; Hall, Martica; Zheng, Huiyong; Gold, Ellen B; Buysse, Daniel J

2011-09-01

Examine associations of vasomotor and mood symptoms with visually scored and computer-generated measures of EEG sleep. Cross-sectional analysis. Community-based in-home polysomnography (PSG). 343 African American, Caucasian, and Chinese women; ages 48-58 years; pre-, peri- or post-menopausal; participating in the Study of Women's Health Across the Nation Sleep Study (SWAN Sleep Study). None. Measures included PSG-assessed sleep duration, continuity, and architecture, delta sleep ratio (DSR) computed from automated counts of delta wave activity, daily diary-assessed vasomotor symptoms (VMS), questionnaires to collect mood (depression, anxiety) symptoms, medication, and lifestyle information, and menopausal status using bleeding criteria. Sleep outcomes were modeled using linear regression. Nocturnal VMS were associated with longer sleep time. Higher anxiety symptom scores were associated with longer sleep latency and lower sleep efficiency, but only in women reporting nocturnal VMS. Contrary to expectations, VMS and mood symptoms were unrelated to either DSR or REM latency. Vasomotor symptoms moderated associations of anxiety with EEG sleep measures of sleep latency and sleep efficiency and was associated with longer sleep duration in this multi-ethnic sample of midlife women.

Dura mater graft-associated Creutzfeldt-Jakob disease with 30-year incubation period.

PubMed

Shijo, Masahiro; Honda, Hiroyuki; Koyama, Sachiko; Ishitsuka, Koji; Maeda, Koichiro; Kuroda, Junya; Tanii, Mitsugu; Kitazono, Takanari; Iwaki, Toru

2017-06-01

Over 60% of all patients with dura mater graft-associated Creutzfeldt-Jakob disease (dCJD) have been diagnosed in Japan. The incubation period has ranged from 1 to 30 years and the age at onset from 15 to 80 years. Here, we report a 77-year-old male Japanese autopsied dCJD case with the longest incubation period so far in Japan. He received a cadaveric dural graft at the right cranial convexity following a craniotomy for meningioma at the age of 46. At 30 years post-dural graft placement, disorientation was observed as an initial symptom of dCJD. He rapidly began to present with inconsistent speech, cognitive impairment and tremor of the left upper extremity. Occasional myoclonic jerks were predominantly observed on the left side. Brain MRI presented hyperintense signals on diffusion-weighted and T2-weighted images, at the right cerebral cortex. The most hyperintense lesion was located at the right parietal lobe, where the dura mater graft had been transplanted. Single-photon emission CT scan showed markedly decreased cerebral blood flow at the right parietal lobe. EEG revealed diffuse and slow activities with periodic sharp-wave complex discharges seen in the right parietal, temporal and occipital lobes. He died of pneumonia 9 months after onset. Brain pathology revealed non-plaque-type dCJD. Laterality of neuropathological changes, including spongiform change, neuronal loss, gliosis or PrP deposits, was not evident. Western blot analysis showed type 1 PrP CJD . Alzheimer-type pathology and PSP-like pathology were also observed. © 2016 Japanese Society of Neuropathology.

β oscillation during slow wave sleep and rapid eye movement sleep in the electroencephalogram of a transgenic mouse model of Huntington's disease.

PubMed

Jeantet, Yannick; Cayzac, Sebastien; Cho, Yoon H

2013-01-01

To search for early abnormalities in electroencephalogram (EEG) during sleep which may precede motor symptoms in a transgenic mouse model of hereditary neurodegenerative Huntington's disease (HD). In the R6/1 transgenic mouse model of HD, rhythmic brain activity in EEG recordings was monitored longitudinally and across vigilance states through the onset and progression of disease. Mice with chronic electrode implants were recorded monthly over wake-sleep cycles (4 hours), beginning at 9-11 weeks (presymptomatic period) through 6-7 months (symptomatic period). Recording data revealed a unique β rhythm (20-35 Hz), present only in R6/1 transgenic mice, which evolves in close parallel with the disease. In addition, there was an unusual relationship between this β oscillation and vigilance states: while nearly absent during the active waking state, the β oscillation appeared with drowsiness and during slow wave sleep (SWS) and, interestingly, strengthened rather than dissipating when the brain returned to an activated state during rapid eye movement (REM) sleep. In addition to providing a new in vivo biomarker and insight into Huntington's disease pathophysiology, this serendipitous observation opens a window onto the rarely explored neurophysiology of the cortico-basal ganglia circuit during SWS and REM sleep.

β Oscillation during Slow Wave Sleep and Rapid Eye Movement Sleep in the Electroencephalogram of a Transgenic Mouse Model of Huntington’s Disease

PubMed Central

Jeantet, Yannick; Cayzac, Sebastien; Cho, Yoon H.

2013-01-01

Study objectives To search for early abnormalities in electroencephalogram (EEG) during sleep which may precede motor symptoms in a transgenic mouse model of hereditary neurodegenerative Huntington’s disease (HD). Design In the R6/1 transgenic mouse model of HD, rhythmic brain activity in EEG recordings was monitored longitudinally and across vigilance states through the onset and progression of disease. Measurements and results Mice with chronic electrode implants were recorded monthly over wake-sleep cycles (4 hours), beginning at 9–11 weeks (presymptomatic period) through 6–7 months (symptomatic period). Recording data revealed a unique β rhythm (20–35 Hz), present only in R6/1 transgenic mice, which evolves in close parallel with the disease. In addition, there was an unusual relationship between this β oscillation and vigilance states: while nearly absent during the active waking state, the β oscillation appeared with drowsiness and during slow wave sleep (SWS) and, interestingly, strengthened rather than dissipating when the brain returned to an activated state during rapid eye movement (REM) sleep. Conclusions In addition to providing a new in vivo biomarker and insight into Huntington's disease pathophysiology, this serendipitous observation opens a window onto the rarely explored neurophysiology of the cortico-basal ganglia circuit during SWS and REM sleep. PMID:24244517

The impact of blackcurrant juice on attention, mood and brain wave spectral activity in young healthy volunteers.

PubMed

Watson, A W; Okello, E J; Brooker, H J; Lester, S; McDougall, G J; Wesnes, K A

2018-01-17

There is a growing body of evidence from randomized controlled trials which indicates that consumption of berries has a positive effect upon the cognitive function of healthy adults. It has been recommended that studies combining cognitive and physiological measures be undertaken in order to strengthen the evidence base for the putative effects of flavonoid consumption on cognitive outcomes. This pilot study utilized a randomized, double-blind and placebo controlled crossover design to assess the influence of the acute administration of anthocyanin-rich blackcurrant juice, standardized at 500 mg of polyphenols, on mood and attention. Additionally, this trial used electroencephalography (EEG) to assess if any changes in cognitive performance are associated with changes in localized prefrontal cortex neuronal activity in nine healthy young adults. Outcomes from the pilot EEG data highlight an anxiolytic effect of the consumption of a single serve blackcurrant juice, as indexed by a suppression of α spectral power, and an increase in the slow wave δ and θ spectral powers. There was also an indication of greater alertness and lower fatigue, as indexed by an increase in β power and suppression of α spectral power. Outcomes from the CogTrack™ system indicated a small acute increase in reaction times during the digit vigilance task.

Impact of Dronabinol on Quantitative Electroencephalogram (qEEG) Measures of Sleep in Obstructive Sleep Apnea Syndrome

PubMed Central

Farabi, Sarah S.; Prasad, Bharati; Quinn, Lauretta; Carley, David W.

2014-01-01

Study Objectives: To determine the effects of dronabinol on quantitative electroencephalogram (EEG) markers of the sleep process, including power distribution and ultradian cycling in 15 patients with obstructive sleep apnea (OSA). Methods: EEG (C4-A1) relative power (% total) in the delta, theta, alpha, and sigma bands was quantified by fast Fourier transformation (FFT) over 28-second intervals. An activation ratio (AR = [alpha + sigma] / [delta + theta]) also was computed for each interval. To assess ultradian rhythms, the best-fitting cosine wave was determined for AR and each frequency band in each polysomnogram (PSG). Results: Fifteen subjects were included in the analysis. Dronabinol was associated with significantly increased theta power (p = 0.002). During the first half of the night, dronabinol decreased sigma power (p = 0.03) and AR (p = 0.03), and increased theta power (p = 0.0006). At increasing dronabinol doses, ultradian rhythms accounted for a greater fraction of EEG power variance in the delta band (p = 0.04) and AR (p = 0.03). Females had higher amplitude ultradian rhythms than males (theta: p = 0.01; sigma: p = 0.01). Decreasing AHI was associated with increasing ultradian rhythm amplitudes (sigma: p < 0.001; AR: p = 0.02). At the end of treatment, lower relative power in the theta band (p = 0.02) and lower AHI (p = 0.05) correlated with a greater decrease in sleepiness from baseline. Conclusions: This exploratory study demonstrates that in individuals with OSA, dronabinol treatment may yield a shift in EEG power toward delta and theta frequencies and a strengthening of ultradian rhythms in the sleep EEG. Citation: Farabi SS; Prasad B; Quinn L; Carley DW. Impact of dronabinol on quantitative electroencephalogram (qEEG) measures of sleep in obstructive sleep apnea syndrome. J Clin Sleep Med 2014;10(1):49-56. PMID:24426820

[Expressive language disorder and focal paroxysmal activity].

PubMed

Valdizán, José R; Rodríguez-Mena, Diego; Díaz-Sardi, Mauricio

2011-03-01

In cases of expressive language disorder (ELD), the child is unable to put his or her thoughts into words. Comorbidity is present with difficulties in repeating, imitating or naming. There are no problems with pronunciation, as occurs in phonological disorder, it may present before the age of three years and is crucial between four and seven years of age. Electroencephalogram (EEG) studies have been carried out not only in ELD, but also in clinical pictures where the language disorder was the main symptom or was associated to another neurodevelopmental pathology. We conducted a retrospective study involving a review of 100 patient records, with patients (25 girls and 75 boys) aged between two and six years old who had been diagnosed with ELD (according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revised) and were free of seizures and not receiving treatment. They were submitted to an EEG and received treatment with valproic acid if EEG findings were positive. Only six patients (males) presented localised spike-wave paroxysmal EEG activity in the frontotemporal region. This 6% is a percentage that is higher than the one found in the normal children's population (2%), but lower than the value indicated in the literature for language disorders, which ranges between 20% and 50%. These patients responded positively to the treatment and both expressive language and EEG findings improved. It is possible that in ELD without paroxysms there may be a dysfunction in the circuit made up of the motor cortex-neostriatum prior to grammatical learning, whereas if there are paroxysms then this would point to neuronal hyperactivity, perhaps associated to this dysfunction or not, in cortical areas. In our cases valproic acid, together with speech therapy, helped the children to recover their language abilities.

Seizure threshold increases can be predicted by EEG quality in right unilateral ultrabrief ECT.

PubMed

Gálvez, Verònica; Hadzi-Pavlovic, Dusan; Waite, Susan; Loo, Colleen K

2017-12-01

Increases in seizure threshold (ST) over a course of brief pulse ECT can be predicted by decreases in EEG quality, informing ECT dose adjustment to maintain adequate supra-threshold dosing. ST increases also occur over a course of right unilateral ultrabrief (RUL UB) ECT, but no data exist on the relationship between ST increases and EEG indices. This study (n = 35) investigated if increases in ST over RUL UB ECT treatments could be predicted by a decline in seizure quality. ST titration was performed at ECT session one and seven, with treatment dosing maintained stable (at 6-8 times ST) in intervening sessions. Seizure quality indices (slow-wave onset, mid-ictal amplitude, regularity, stereotypy, and post-ictal suppression) were manually rated at the first supra-threshold treatment, and last supra-threshold treatment before re-titration, using a structured rating scale, by a single trained rater blinded to the ECT session being rated. Twenty-one subjects (60%) had a ST increase. The association between ST changes and EEG quality indices was analysed by logistic regression, yielding a significant model (p < 0.001). Initial ST (p < 0.05) and percentage change in mid-ictal amplitude (p < 0.05) were significant predictors of change in ST. Percentage change in post-ictal suppression reached trend level significance (p = 0.065). Increases in ST over a RUL UB ECT course may be predicted by decreases in seizure quality, specifically decline in mid-ictal amplitude and potentially in post-ictal suppression. Such EEG indices may be able to inform when dose adjustments are necessary to maintain adequate supra-threshold dosing in RUL UB ECT.

Restricting Time in Bed in Early Adolescence Reduces Both NREM and REM Sleep but Does Not Increase Slow Wave EEG.

PubMed

Campbell, Ian G; Kraus, Amanda M; Burright, Christopher S; Feinberg, Irwin

2016-09-01

School night total sleep time decreases across adolescence (9-18 years) by 10 min/year. This decline is comprised entirely of a selective decrease in NREM sleep; REM sleep actually increases slightly. Decreasing sleep duration across adolescence is often attributed to insufficient time in bed. Here we tested whether sleep restriction in early adolescence produces the same sleep stage changes observed on school nights across adolescence. All-night sleep EEG was recorded in 76 children ranging in age from 9.9 to 14.0 years. Each participant kept 3 different sleep schedules that consisted of 3 nights of 8.5 h in bed followed by 4 nights of either 7, 8.5, or 10 h in bed. Sleep stage durations and NREM delta EEG activity were compared across the 3 time in bed conditions. Shortening time in bed from 10 to 7 hours reduced sleep duration by approximately 2 hours, roughly equal to the decrease in sleep duration we recorded longitudinally across adolescence. However, sleep restriction significantly reduced both NREM (by 83 min) and REM (by 47 min) sleep. Sleep restriction did not affect NREM delta EEG activity. Our findings suggest that the selective NREM reduction and the small increase in REM we observed longitudinally across 9-18 years are not produced by sleep restriction. We hypothesize that the selective NREM decline reflects adolescent brain maturation (synaptic elimination) that reduces the need for the restorative processes of NREM sleep. © 2016 Associated Professional Sleep Societies, LLC.

Studying frequency processing of the brain to enhance long-term memory and develop a human brain protocol.

PubMed

Friedrich, Wernher; Du, Shengzhi; Balt, Karlien

2015-01-01

The temporal lobe in conjunction with the hippocampus is responsible for memory processing. The gamma wave is involved with this process. To develop a human brain protocol, a better understanding of the relationship between gamma and long-term memory is vital. A more comprehensive understanding of the human brain and specific analogue waves it uses will support the development of a human brain protocol. Fifty-eight participants aged between 6 and 60 years participated in long-term memory experiments. It is envisaged that the brain could be stimulated through binaural beats (sound frequency) at 40 Hz (gamma) to enhance long-term memory capacity. EEG recordings have been transformed to sound and then to an information standard, namely ASCII. Statistical analysis showed a proportional relationship between long-term memory and gamma activity. Results from EEG recordings indicate a pattern. The pattern was obtained through the de-codification of an EEG recording to sound and then to ASCII. Stimulation of gamma should enhance long term memory capacity. More research is required to unlock the human brains' protocol key. This key will enable the processing of information directly to and from human memory via gamma, the hippocampus and the temporal lobe.

Infantile spasms.

PubMed

Hrachovy, Richard A; Frost, James D

2013-01-01

Infantile spasms are a unique disorder of infancy and early childhood. The average age at onset of infantile spasms is 6 months and the average incidence of the disorder is approximately 0.31 per 1000 live births. Approximately one-quarter of patients will spontaneously stop having spasms within 1 year of onset. There are three main types of epileptic spasms: flexor, extensor, and mixed flexor-extensor. Spasms frequently occur in clusters and commonly occur upon arousal from sleep. The motor spasms are frequently confused with other normal and abnormal infant behaviors. Typically, the interictal EEG reveals hypsarrhythmia or one of its variants. A variety of ictal EEG patterns may be seen, the most common of which is a generalized slow-wave transient followed by an attenuation of the background activity in all regions. The primary treatment objective is to improve the EEG and stop the spasms as soon as possible and to avoid prolonged treatment durations with any form of therapy. Currently, there is no conclusive evidence that medical or surgical treatment of infantile spasms significantly alters long-term outcome. Although the pathophysiological mechanism underlying infantile spasms is unknown, several animal models of infantile spasms have been developed in recent years. Copyright © 2013 Elsevier B.V. All rights reserved.

Person authentication using brainwaves (EEG) and maximum a posteriori model adaptation.

PubMed

Marcel, Sébastien; Millán, José Del R

2007-04-01

In this paper, we investigate the use of brain activity for person authentication. It has been shown in previous studies that the brain-wave pattern of every individual is unique and that the electroencephalogram (EEG) can be used for biometric identification. EEG-based biometry is an emerging research topic and we believe that it may open new research directions and applications in the future. However, very little work has been done in this area and was focusing mainly on person identification but not on person authentication. Person authentication aims to accept or to reject a person claiming an identity, i.e., comparing a biometric data to one template, while the goal of person identification is to match the biometric data against all the records in a database. We propose the use of a statistical framework based on Gaussian Mixture Models and Maximum A Posteriori model adaptation, successfully applied to speaker and face authentication, which can deal with only one training session. We perform intensive experimental simulations using several strict train/test protocols to show the potential of our method. We also show that there are some mental tasks that are more appropriate for person authentication than others.

Nonlinear analysis of EEG for epileptic seizures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hively, L.M.; Clapp, N.E.; Daw, C.S.

1995-04-01

We apply chaotic time series analysis (CTSA) to human electroencephalogram (EEG) data. Three epoches were examined: epileptic seizure, non-seizure, and transition from non-seizure to seizure. The CTSA tools were applied to four forms of these data: raw EEG data (e-data), artifact data (f-data) via application of a quadratic zero-phase filter of the raw data, artifact-filtered data (g- data) and that was the residual after subtracting f-data from e-data, and a low-pass-filtered version (h-data) of g-data. Two different seizures were analyzed for the same patient. Several nonlinear measures uniquely indicate an epileptic seizure in both cases, including an abrupt decrease inmore » the time per wave cycle in f-data, an abrupt increase in the Kolmogorov entropy and in the correlation dimension for e-h data, and an abrupt increase in the correlation dimension for e-h data. The transition from normal to seizure state also is characterized by distinctly different trends in the nonlinear measures for each seizure and may be potential seizure predictors for this patient. Surrogate analysis of e-data shows that statistically significant nonlinear structure is present during the non-seizure, transition , and seizure epoches.« less

Sharp low-energy feature in single-particle spectra due to forward scattering in d-wave cuprate superconductors.

PubMed

Hong, Seung Hwan; Bok, Jin Mo; Zhang, Wentao; He, Junfeng; Zhou, X J; Varma, C M; Choi, Han-Yong

2014-08-01

There is an enormous interest in the renormalization of the quasiparticle (qp) dispersion relation of cuprate superconductors both below and above the critical temperature T_{c} because it enables the determination of the fluctuation spectrum to which the qp's are coupled. A remarkable discovery by angle-resolved photoemission spectroscopy (ARPES) is a sharp low-energy feature (LEF) in qp spectra well below the superconducting energy gap but with its energy increasing in proportion to T_{c} and its intensity increasing sharply below T_{c}. This unexpected feature needs to be reconciled with d-wave superconductivity. Here, we present a quantitative analysis of ARPES data from Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} (Bi2212) using Eliashberg equations to show that the qp scattering rate due to the forward scattering impurities far from the Cu-O planes is modified by the energy gap below T_{c} and shows up as the LEF. This is also a necessary step to analyze ARPES data to reveal the spectrum of fluctuations promoting superconductivity.

Probing the ionization wave packet and recollision dynamics with an elliptically polarized strong laser field in the nondipole regime

NASA Astrophysics Data System (ADS)

Maurer, J.; Willenberg, B.; Daněk, J.; Mayer, B. W.; Phillips, C. R.; Gallmann, L.; Klaiber, M.; Hatsagortsyan, K. Z.; Keitel, C. H.; Keller, U.

2018-01-01

We explore ionization and rescattering in strong mid-infrared laser fields in the nondipole regime over the full range of polarization ellipticity. In three-dimensional photoelectron momentum distributions (3D PMDs) measured with velocity map imaging spectroscopy, we observe the appearance of a sharp ridge structure along the major polarization axis. Within a certain range of ellipticity, the electrons in this ridge are clearly separated from the two lobes that commonly appear in the PMD with elliptically polarized laser fields. In contrast to the well-known lobes of direct electrons, the sharp ridge is created by Coulomb focusing of the softly recolliding electrons. These ridge electrons are directly related to a counterintuitive shift of the PMD peak opposite to the laser beam propagation direction when the dipole approximation breaks down. The ellipticity-dependent 3D PMDs give access to different ionization and recollision dynamics with appropriate filters in the momentum space. For example, we can extract information about the spread of the initial wave packet and the Coulomb momentum transfer of the rescattering electrons.

Reconstruction of gastric slow wave from finger photoplethysmographic signal using radial basis function neural network.

PubMed

Mohamed Yacin, S; Srinivasa Chakravarthy, V; Manivannan, M

2011-11-01

Extraction of extra-cardiac information from photoplethysmography (PPG) signal is a challenging research problem with significant clinical applications. In this study, radial basis function neural network (RBFNN) is used to reconstruct the gastric myoelectric activity (GMA) slow wave from finger PPG signal. Finger PPG and GMA (measured using Electrogastrogram, EGG) signals were acquired simultaneously at the sampling rate of 100 Hz from ten healthy subjects. Discrete wavelet transform (DWT) was used to extract slow wave (0-0.1953 Hz) component from the finger PPG signal; this slow wave PPG was used to reconstruct EGG. A RBFNN is trained on signals obtained from six subjects in both fasting and postprandial conditions. The trained network is tested on data obtained from the remaining four subjects. In the earlier study, we have shown the presence of GMA information in finger PPG signal using DWT and cross-correlation method. In this study, we explicitly reconstruct gastric slow wave from finger PPG signal by the proposed RBFNN-based method. It was found that the network-reconstructed slow wave provided significantly higher (P < 0.0001) correlation (≥ 0.9) with the subject's EGG slow wave than the correlation obtained (≈0.7) between the PPG slow wave from DWT and the EEG slow wave. Our results showed that a simple finger PPG signal can be used to reconstruct gastric slow wave using RBFNN method.

Optogenetic activation of septal cholinergic neurons suppresses sharp wave ripples and enhances theta oscillations in the hippocampus.

PubMed

Vandecasteele, Marie; Varga, Viktor; Berényi, Antal; Papp, Edit; Barthó, Péter; Venance, Laurent; Freund, Tamás F; Buzsáki, György

2014-09-16

Theta oscillations in the limbic system depend on the integrity of the medial septum. The different populations of medial septal neurons (cholinergic and GABAergic) are assumed to affect different aspects of theta oscillations. Using optogenetic stimulation of cholinergic neurons in ChAT-Cre mice, we investigated their effects on hippocampal local field potentials in both anesthetized and behaving mice. Cholinergic stimulation completely blocked sharp wave ripples and strongly suppressed the power of both slow oscillations (0.5-2 Hz in anesthetized, 0.5-4 Hz in behaving animals) and supratheta (6-10 Hz in anesthetized, 10-25 Hz in behaving animals) bands. The same stimulation robustly increased both the power and coherence of theta oscillations (2-6 Hz) in urethane-anesthetized mice. In behaving mice, cholinergic stimulation was less effective in the theta (4-10 Hz) band yet it also increased the ratio of theta/slow oscillation and theta coherence. The effects on gamma oscillations largely mirrored those of theta. These findings show that medial septal cholinergic activation can both enhance theta rhythm and suppress peri-theta frequency bands, allowing theta oscillations to dominate.

Effects of joint attention on long-term memory in 9-month-old infants: an event-related potentials study.

PubMed

Kopp, Franziska; Lindenberger, Ulman

2011-07-01

Joint attention develops during the first year of life but little is known about its effects on long-term memory. We investigated whether joint attention modulates long-term memory in 9-month-old infants. Infants were familiarized with visually presented objects in either of two conditions that differed in the degree of joint attention (high versus low). EEG indicators in response to old and novel objects were probed directly after the familiarization phase (immediate recognition), and following a 1-week delay (delayed recognition). In immediate recognition, the amplitude of positive slow-wave activity was modulated by joint attention. In the delayed recognition, the amplitude of the Pb component differentiated between high and low joint attention. In addition, the positive slow-wave amplitude during immediate and delayed recognition correlated with the frequency of infants' looks to the experimenter during familiarization. Under both high- and low-joint-attention conditions, the processing of unfamiliar objects was associated with an enhanced Nc component. Our results show that the degree of joint attention modulates EEG during immediate and delayed recognition. We conclude that joint attention affects long-term memory processing in 9-month-old infants by enhancing the relevance of attended items. © 2010 Blackwell Publishing Ltd.

Electroencephalogram spindle activity during dexmedetomidine sedation and physiological sleep.

PubMed

Huupponen, E; Maksimow, A; Lapinlampi, P; Särkelä, M; Saastamoinen, A; Snapir, A; Scheinin, H; Scheinin, M; Meriläinen, P; Himanen, S-L; Jääskeläinen, S

2008-02-01

Dexmedetomidine, a selective alpha(2)-adrenoceptor agonist, induces a unique, sleep-like state of sedation. The objective of the present work was to study human electroencephalogram (EEG) sleep spindles during dexmedetomidine sedation and compare them with spindles during normal physiological sleep, to test the hypothesis that dexmedetomidine exerts its effects via normal sleep-promoting pathways. EEG was continuously recorded from a bipolar frontopolar-laterofrontal derivation with Entropy Module (GE Healthcare) during light and deep dexmedetomidine sedation (target-controlled infusions set at 0.5 and 3.2 ng/ml) in 11 healthy subjects, and during physiological sleep in 10 healthy control subjects. Sleep spindles were visually scored and quantitatively analyzed for density, duration, amplitude (band-pass filtering) and frequency content (matching pursuit approach), and compared between the two groups. In visual analysis, EEG activity during dexmedetomidine sedation was similar to physiological stage 2 (S2) sleep with slight to moderate amount of slow-wave activity and abundant sleep spindle activity. In quantitative EEG analyses, sleep spindles were similar during dexmedetomidine sedation and normal sleep. No statistically significant differences were found in spindle density, amplitude or frequency content, but the spindles during dexmedetomidine sedation had longer duration (mean 1.11 s, SD 0.14 s) than spindles in normal sleep (mean 0.88 s, SD 0.14 s; P=0.0014). Analysis of sleep spindles shows that dexmedetomidine produces a state closely resembling physiological S2 sleep in humans, which gives further support to earlier experimental evidence for activation of normal non-rapid eye movement sleep-promoting pathways by this sedative agent.

Sleep homeostasis in the female rat during the estrous cycle.

PubMed

Schwierin, B; Borbély, A A; Tobler, I

1998-11-16

To investigate whether sleep homeostasis in the female rat is modulated by the estrous cycle, the vigilance states, EEG power spectra and cortical temperature (TCRT) were assessed on the basis of 4-day continuous recordings. A regulatory response was elicited by 6-h sleep deprivation (SD) during the proestrous (PRO) and the estrous (EST) day and compared to the baseline recordings. The vigilance states varied across the estrous cycle. In the PRO dark period the amount of sleep was reduced. The decrease in rapid-eye-movement (REM) sleep was already evident towards the end of the preceding light period, and an increased fragmentation of sleep was present throughout PRO. Compared to the other days of the estrous cycle, slow-wave activity (SWA; EEG power density 0.75-4.75 Hz) in nonREM (NREM) sleep was lower in PRO at the end of the light period and in the beginning of the dark period. High-frequency activity (HFA; EEG power density 10.25-25.0 Hz) was increased in the dark period of PRO. The SD performed during the first 6 h of the light period of PRO and EST enhanced SWA in NREM sleep and reduced sleep fragmentation during the subsequent 6 h. The extent and time course of the response to SD did not differ between the two phases of the estrous cycle. It is concluded that despite the marked baseline variations of the vigilance states and the EEG, homeostatic regulation is little affected by the estrous cycle. Copyright 1998 Elsevier Science B.V.

Determining the degree of synchronism for intermittent phase synchronization in human electroencephalography data

NASA Astrophysics Data System (ADS)

Koloskova, A. D.; Moskalenko, O. I.

2017-05-01

The phenomenon of intermittent phase synchronization during development of epileptic activity in human beings has been discovered based on EEG data. The presence of synchronous behavior phases has been detected both during spike-wave discharges and in the regions of background activity of the brain. The degree of synchronism in the intermittent phase-synchronization regime in both cases has been determined, and it has been established that spike-wave discharges are characterized by a higher degree of synchronism than exists in the regions of background activity of the brain. To determine the degree of synchronism, a modified method of evaluating zero conditional Lyapunov exponents from time series is proposed.

Old Brains Come Uncoupled in Sleep: Slow Wave-Spindle Synchrony, Brain Atrophy, and Forgetting.

PubMed

Helfrich, Randolph F; Mander, Bryce A; Jagust, William J; Knight, Robert T; Walker, Matthew P

2018-01-03

The coupled interaction between slow-wave oscillations and sleep spindles during non-rapid-eye-movement (NREM) sleep has been proposed to support memory consolidation. However, little evidence in humans supports this theory. Moreover, whether such dynamic coupling is impaired as a consequence of brain aging in later life, contributing to cognitive and memory decline, is unknown. Combining electroencephalography (EEG), structural MRI, and sleep-dependent memory assessment, we addressed these questions in cognitively normal young and older adults. Directional cross-frequency coupling analyses demonstrated that the slow wave governs a precise temporal coordination of sleep spindles, the quality of which predicts overnight memory retention. Moreover, selective atrophy within the medial frontal cortex in older adults predicted a temporal dispersion of this slow wave-spindle coupling, impairing overnight memory consolidation and leading to forgetting. Prefrontal-dependent deficits in the spatiotemporal coordination of NREM sleep oscillations therefore represent one pathway explaining age-related memory decline. Copyright © 2017 Elsevier Inc. All rights reserved.

Terahertz-wave near-field imaging with subwavelength resolution using surface-wave-assisted bow-tie aperture

NASA Astrophysics Data System (ADS)

Ishihara, Kunihiko; Ohashi, Keishi; Ikari, Tomofumi; Minamide, Hiroaki; Yokoyama, Hiroyuki; Shikata, Jun-ichi; Ito, Hiromasa

2006-11-01

We demonstrate the terahertz-wave near-field imaging with subwavelength resolution using a bow-tie shaped aperture surrounded by concentric periodic structures in a metal film. A subwavelength aperture with concentric periodic grooves, which are known as a bull's eye structure, shows extremely large enhanced transmission beyond the diffraction limit caused by the resonant excitation of surface waves. Additionally, a bow-tie aperture exhibits extraordinary field enhancement at the sharp tips of the metal, which enhances the transmission and the subwavelength spatial resolution. We introduced a bow-tie aperture to the bull's eye structure and achieved high spatial resolution (˜λ/17) in the near-field region. The terahertz-wave near-field image of the subwavelength metal pattern (pattern width=20μm) was obtained for the wavelength of 207μm.

Application of the wavenumber jump condition to the normal and oblique interaction of a plane acoustic wave and a plane shock

NASA Technical Reports Server (NTRS)

Kleinstein, G. G.; Gunzburger, M. D.

1977-01-01

The kinematics of normal and oblique interactions between a plane acoustic wave and a plane shock wave are investigated separately using an approach whereby the shock is considered as a sharp discontinuity surface separating two half-spaces, so that the dispersion relation on either side of the shock and the wavenumber jump condition across a discontinuity surface completely specify the kinematics of the problem in the whole space independently of the acoustic-field dynamics. The normal interaction is analyzed for a stationary shock, and the spectral change of the incident wave is investigated. The normal interaction is then examined for the case of a shock wave traveling into an ambient region where an acoustic disturbance is propagating in the opposite direction. Detailed attention is given to the consequences of the existence of a critical shock speed above which the frequency of the transmitted wave becomes negative. Finally, the oblique interaction with a fixed shock is considered, and the existence and nature of the transmitted wave is investigated, particularly as a function of the angle of incidence.

A frequency domain linearized Navier-Stokes equations approach to acoustic propagation in flow ducts with sharp edges.

PubMed

Kierkegaard, Axel; Boij, Susann; Efraimsson, Gunilla

2010-02-01

Acoustic wave propagation in flow ducts is commonly modeled with time-domain non-linear Navier-Stokes equation methodologies. To reduce computational effort, investigations of a linearized approach in frequency domain are carried out. Calculations of sound wave propagation in a straight duct are presented with an orifice plate and a mean flow present. Results of transmission and reflections at the orifice are presented on a two-port scattering matrix form and are compared to measurements with good agreement. The wave propagation is modeled with a frequency domain linearized Navier-Stokes equation methodology. This methodology is found to be efficient for cases where the acoustic field does not alter the mean flow field, i.e., when whistling does not occur.

Pretreatment with β-adrenergic receptor agonists facilitates induction of LTP and sharp wave ripple complexes in rodent hippocampus.

PubMed

Ul Haq, Rizwan; Anderson, Marlene; Liotta, Agustin; Shafiq, Maria; Sherkheli, Muhammad Azhar; Heinemann, Uwe

2016-12-01

Norepinephrine, is involved in the enhancement of learning and memory formation by regulating synaptic mechanisms through its ability to activate pre- and post-synaptic adrenergic receptors. Here we show that β-agonists of norepinephrine facilitate the induction of both associational LTP and sharp wave ripples (SPW-Rs) in acute slices of rat hippocampus in area CA3. Surprisingly, this facilitating effect persists when slices are only pretreated with β-receptor agonists followed by wash out and application of the unspecific β-adrenoreceptor (βAR) antagonist propranolol. During application of βAR agonists repeated stimulation resulted in facilitated induction of SPW-Rs. Since SPW-Rs are thought to be involved in memory replay we studied the effects of βAR-agonists on spontaneous SPW-Rs in murine hippocampus and found that amplitude and incidence of SPW-Rs increased. These effects involve cyclic-AMP and the activation of protein kinase A and suggest a supportive role in memory consolidation. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Unsteady separation in sharp fin-induced shock wave/turbulent boundary layer interaction at Mach 5

NASA Technical Reports Server (NTRS)

Schmisseur, J. D.; Dolling, D. S.

1992-01-01

Fluctuating wall-pressure measurements are made in shock-wave/turbulent-boundary-layer interactions generated by sharp/unswept fins at angles of attack of 16, 18, 20, 22, 24, 26, and 28 degrees at Mach 5. The experiment was conducted under approximately adiabatic wall temperature conditions. The mean and rms pressure distributions can be collapsed in conical coordinates. The wall-pressure signal near separation is intermittent for all angles of attack (16-28 deg) and is qualitatively similar to that measured in unswept flows. However, the shock frequencies are higher - about 5 kHz compared to 0.5-1 kHz. Over the range of sweepbacks examined, from 25-55 deg, the spectral content of the fluctuating pressures does not change. Thus, the increase in separation-shock frequency from 1 to 5 kHz occurs at lower interaction sweepback and is not a continuous process with increasing sweepback. Power spectra at the position of maximum rms in the intermittent region for interactions in different incoming boundary layers have the same center frequency. The maximum rms in the intermittent region correlates with interaction sweepback, not with overall inviscid pressure rise.

The effects of age and gender on sleep EEG power spectral density in the middle years of life (ages 20-60 years old)

NASA Technical Reports Server (NTRS)

Carrier, J.; Land, S.; Buysse, D. J.; Kupfer, D. J.; Monk, T. H.

2001-01-01

The effects of age and gender on sleep EEG power spectral density were assessed in a group of 100 subjects aged 20 to 60 years. We propose a new statistical strategy (mixed-model using fixed-knot regression splines) to analyze quantitative EEG measures. The effect of gender varied according to frequency, but no interactions emerged between age and gender, suggesting that the aging process does not differentially influence men and women. Women had higher power density than men in delta, theta, low alpha, and high spindle frequency range. The effect of age varied according to frequency and across the night. The decrease in power with age was not restricted to slow-wave activity, but also included theta and sigma activity. With increasing age, the attenuation over the night in power density between 1.25 and 8.00 Hz diminished, and the rise in power between 12.25 and 14.00 Hz across the night decreased. Increasing age was associated with higher power in the beta range. These results suggest that increasing age may be related to an attenuation of homeostatic sleep pressure and to an increase in cortical activation during sleep.

Nonlinear structures and anomalous transport in partially magnetized E×B plasmas

DOE PAGES

Janhunen, Salomon; Smolyakov, Andrei; Chapurin, Oleksandr; ...

2017-12-29

Nonlinear dynamics of the electron-cyclotron instability driven by the electron E x B current in a crossed electric and magnetic field is studied. In the nonlinear regime, the instability proceeds by developing a large amplitude coherent wave driven by the energy input from the fundamental cyclotron resonance. Further evolution shows the formation of the long wavelength envelope akin to the modulational instability. Simultaneously, the ion density shows the development of a high-k content responsible for wave focusing and sharp peaks on the periodic cnoidal wave structure. Here, it is shown that the anomalous electron transport (along the direction of themore » applied electric field) is dominated by the long wavelength part of the turbulent spectrum.« less

Cannabis Essential Oil: A Preliminary Study for the Evaluation of the Brain Effects.

PubMed

Gulluni, Nadia; Re, Tania; Loiacono, Idalba; Lanzo, Giovanni; Gori, Luigi; Macchi, Claudio; Epifani, Francesco; Bragazzi, Nicola; Firenzuoli, Fabio

2018-01-01

We examined the effects of essential oil from legal (THC <0.2% w/v) hemp variety on the nervous system in 5 healthy volunteers. GC/EIMS and GC/FID analysis of the EO showed that the main components were myrcene and β -caryophyllene. The experiment consisted of measuring autonomic nervous system (ANS) parameters; evaluations of the mood state; and electroencephalography (EEG) recording before treatment, during treatment, and after hemp inhalation periods as compared with control conditions. The results revealed decreased diastolic blood pressure, increased heart rate, and significant increased skin temperature. The subjects described themselves as more energetic, relaxed, and calm. The analysis EEG showed a significant increase in the mean frequency of alpha (8-13 Hz) and significant decreased mean frequency and relative power of beta 2 (18,5-30 Hz) waves. Moreover, an increased power, relative power, and amplitude of theta (4-8 Hz) and alpha brain waves activities and an increment in the delta wave (0,5-4 Hz) power and relative power was recorded in the posterior region of the brain. These results suggest that the brain wave activity and ANS are affected by the inhalation of the EO of Cannabis sativa suggesting a neuromodular activity in cases of stress, depression, and anxiety.

Cannabis Essential Oil: A Preliminary Study for the Evaluation of the Brain Effects

PubMed Central

Loiacono, Idalba; Lanzo, Giovanni; Gori, Luigi; Macchi, Claudio; Epifani, Francesco

2018-01-01

We examined the effects of essential oil from legal (THC <0.2% w/v) hemp variety on the nervous system in 5 healthy volunteers. GC/EIMS and GC/FID analysis of the EO showed that the main components were myrcene and β-caryophyllene. The experiment consisted of measuring autonomic nervous system (ANS) parameters; evaluations of the mood state; and electroencephalography (EEG) recording before treatment, during treatment, and after hemp inhalation periods as compared with control conditions. The results revealed decreased diastolic blood pressure, increased heart rate, and significant increased skin temperature. The subjects described themselves as more energetic, relaxed, and calm. The analysis EEG showed a significant increase in the mean frequency of alpha (8–13 Hz) and significant decreased mean frequency and relative power of beta 2 (18,5–30 Hz) waves. Moreover, an increased power, relative power, and amplitude of theta (4–8 Hz) and alpha brain waves activities and an increment in the delta wave (0,5–4 Hz) power and relative power was recorded in the posterior region of the brain. These results suggest that the brain wave activity and ANS are affected by the inhalation of the EO of Cannabis sativa suggesting a neuromodular activity in cases of stress, depression, and anxiety. PMID:29576792

Quadratic dissipation effect on the moonpool resonance

NASA Astrophysics Data System (ADS)

Liu, Heng-xu; Chen, Hai-long; Zhang, Liang; Zhang, Wan-chao; Liu, Ming

2017-12-01

This paper adopted a semi-analytical method based on eigenfunction matching to solve the problem of sharp resonance of cylindrical structures with a moonpool that has a restricted entrance. To eliminate the sharp resonance and to measure the viscous effect, a quadratic dissipation is introduced by assuming an additional dissipative disk at the moonpool entrance. The fluid domain is divided into five cylindrical subdomains, and the velocity potential in each subdomain is obtained by meeting the Laplace equation as well as the boundary conditions. The free-surface elevation at the center of the moonpool, along with the pressure and velocity at the restricted entrance for first-order wave are evaluated. By choosing appropriate dissipation coefficients, the free-surface elevation calculated at the center of the moonpool is in coincidence with the measurements in model tests both at the peak period and amplitude at resonance. It is shown that the sharp resonance in the potential flow theory can be eliminated and the viscous effect can be estimated with a simple method in some provided hydrodynamic models.

Evaluation of Wireless Vital Signs Monitor in Trauma Patients

DTIC Science & Technology

2014-06-01

p=NS These data show that the R wave detection and pulse oximeter in the MWVSM finger probe are more accurate and follow changes better than those... oximeter signal failed to register with the thready pulse characteristic of hemorrhagic shock. This observation suggests that using a forehead and...would be more useful to measure from the forehead (e.g. near infrared spectroscopy (NIRS) or Bispectral EEG (BIS)) or extremity? 2) Does pulse

Bradycardia and asystole during generalised interictal EEG discharges.

PubMed

Sforza, Emilia; Pichot, Vincent; Gschwind, Markus; Roche, Frédéric; Maeder-Ingvar, Malin

2014-12-01

Few studies have investigated the effects of interictal epileptic discharges on the cardiac autonomic system. This study reports the case of a 37-year-old man with refractory generalised epilepsy, who recently reported an increase in frequency of nocturnal tonic-clonic seizures, not responding to treatment. During the nocturnal video study, in non-rapid eye movements sleep, we recorded 106 generalised sharp- and polyspike-waves lasting for 3 to 7 seconds, associated with bradycardia and asystole, without behavioural changes and without increase in deltoid muscle activity. The asystole had a duration of between 3 and 8 seconds. In one case, a 7 second asystole was associated with a tonic-clonic generalised seizure. A 24-hour electrocardiographic study revealed a bradycardia and a Wenckebach atrioventricular block. Heart rate analysis at the time of the interictal epileptic discharges revealed an abrupt increase in the RR interval, occurring simultaneously with the onset of interictal epileptic discharges and followed by a return to values below baseline value. A cardiac pacemaker was installed with a reduction of asystole length during the interictal epileptic discharges. Our findings indicate, for the first time, the role of interictal generalised discharges in EEG-related asystole and bradycardia. These data support the hypothesis that some patients with epilepsy may be predisposed to disturbances of the autonomic cardiac system.

An experimental study of a three-dimensional shock wave/turbulent boundary-layer interaction at a hypersonic Mach number

NASA Technical Reports Server (NTRS)

Kussoy, M. I.; Horstman, K. C.; Kim, K.-S.

1991-01-01

Experimental data for a series of three-dimensional shock-wave/turbulent-boundary-layer interaction flows at Mach 8.2 are presented. The test bodies, composed of sharp fins fastened to a flat-plate test surface, were designed to generate flows with varying degrees of pressure gradient, boundary-layer separation, and turning angle. The data include surface-pressure, heat-transfer, and skin-friction distributions, as well as limited mean flowfield surveys both in the undisturbed and interaction regimes. The data were obtained for the purpose of validating computational models of these hypersonic interactions.

Sharp threshold of blow-up and scattering for the fractional Hartree equation

NASA Astrophysics Data System (ADS)

Guo, Qing; Zhu, Shihui

2018-02-01

We consider the fractional Hartree equation in the L2-supercritical case, and find a sharp threshold of the scattering versus blow-up dichotomy for radial data: If M[u0 ]s -sc/sc E [u0 ] < M[ Q ]s -sc/sc E [ Q ] and M[u0 ]s -sc/sc ‖u0‖ H˙s 2 < M[ Q ]s -sc/sc ‖Q‖ H˙s 2 , then the solution u (t) is globally well-posed and scatters; if M[u0 ]s -sc/sc E [u0 ] < M[ Q ]s -sc/sc E [ Q ] and M[u0 ]s -sc/sc ‖u0‖ H˙s 2 > M[ Q ]s -sc/sc ‖Q‖ H˙s 2 , the solution u (t) blows up in finite time. This condition is sharp in the sense that the solitary wave solution eit Q (x) is global but not scattering, which satisfies the equality in the above conditions. Here, Q is the ground-state solution for the fractional Hartree equation.

Epilepsy surgery for epileptic encephalopathy as a sequela of herpes simplex encephalitis: case report.

PubMed

Taskin, Birce Dilge; Tanji, Kurenai; Feldstein, Neil A; McSwiggan-Hardin, Maureen; Akman, Cigdem I

2017-07-01

Herpes simplex virus (HSV) encephalitis can manifest with different clinical presentations, including acute monophasic illness and biphasic chronic granulomatous HSV encephalitis. Chronic encephalitis is much less common, and very rare late relapses are associated with intractable epilepsy and progressive neurological deficits with or without evidence of HSV in the cerebrospinal fluid. The authors report on an 8-year-old girl with a history of treated HSV-1 encephalitis when she was 13 months of age and focal epilepsy when she was 2 years old. Although free of clinical seizures, when she was 5, she experienced behavioral and academic dysfunction, which was later attributed to electrographic focal seizures and worsening electroencephalography (EEG) findings with electrical status epilepticus during slow-wave sleep (ESES). Following a right temporal lobectomy, chronic granulomatous encephalitis was diagnosed. The patient's clinical course improved with the resolution of seizures and EEG abnormalities.

Relationship between delta power and the electrocardiogram-derived cardiopulmonary spectrogram: possible implications for assessing the effectiveness of sleep.

PubMed

Thomas, Robert Joseph; Mietus, Joseph E; Peng, Chung-Kang; Guo, Dan; Gozal, David; Montgomery-Downs, Hawley; Gottlieb, Daniel J; Wang, Cheng-Yen; Goldberger, Ary L

2014-01-01

The physiologic relationship between slow-wave activity (SWA) (0-4 Hz) on the electroencephalogram (EEG) and high-frequency (0.1-0.4 Hz) cardiopulmonary coupling (CPC) derived from electrocardiogram (ECG) sleep spectrograms is not known. Because high-frequency CPC appears to be a biomarker of stable sleep, we tested the hypothesis that that slow-wave EEG power would show a relatively fixed-time relationship to periods of high-frequency CPC. Furthermore, we speculated that this correlation would be independent of conventional nonrapid eye movement (NREM) sleep stages. We analyzed selected datasets from an archived polysomnography (PSG) database, the Sleep Heart Health Study I (SHHS-I). We employed the cross-correlation technique to measure the degree of which 2 signals are correlated as a function of a time lag between them. Correlation analyses between high-frequency CPC and delta power (computed both as absolute and normalized values) from 3150 subjects with an apnea-hypopnea index (AHI) of ≤5 events per hour of sleep were performed. The overall correlation (r) between delta power and high-frequency coupling (HFC) power was 0.40±0.18 (P=.001). Normalized delta power provided improved correlation relative to absolute delta power. Correlations were somewhat reduced in the second half relative to the first half of the night (r=0.45±0.20 vs r=0.34±0.23). Correlations were only affected by age in the eighth decade. There were no sex differences and only small racial or ethnic differences were noted. These results support a tight temporal relationship between slow wave power, both within and outside conventional slow wave sleep periods, and high frequency cardiopulmonary coupling, an ECG-derived biomarker of "stable" sleep. These findings raise mechanistic questions regarding the cross-system integration of neural and cardiopulmonary control during sleep. Copyright © 2013 Elsevier B.V. All rights reserved.

Real-Time Optical Diagnosis of the Rat Brain Exposed to a Laser-Induced Shock Wave: Observation of Spreading Depolarization, Vasoconstriction and Hypoxemia-Oligemia

PubMed Central

Sato, Shunichi; Kawauchi, Satoko; Okuda, Wataru; Nishidate, Izumi; Nawashiro, Hiroshi; Tsumatori, Gentaro

2014-01-01

Despite many efforts, the pathophysiology and mechanism of blast-induced traumatic brain injury (bTBI) have not yet been elucidated, partially due to the difficulty of real-time diagnosis and extremely complex factors determining the outcome. In this study, we topically applied a laser-induced shock wave (LISW) to the rat brain through the skull, for which real-time measurements of optical diffuse reflectance and electroencephalogram (EEG) were performed. Even under conditions showing no clear changes in systemic physiological parameters, the brain showed a drastic light scattering change accompanied by EEG suppression, which indicated the occurrence of spreading depression, long-lasting hypoxemia and signal change indicating mitochondrial energy impairment. Under the standard LISW conditions examined, hemorrhage and contusion were not apparent in the cortex. To investigate events associated with spreading depression, measurement of direct current (DC) potential, light scattering imaging and stereomicroscopic observation of blood vessels were also conducted for the brain. After LISW application, we observed a distinct negative shift in the DC potential, which temporally coincided with the transit of a light scattering wave, showing the occurrence of spreading depolarization and concomitant change in light scattering. Blood vessels in the brain surface initially showed vasodilatation for 3–4 min, which was followed by long-lasting vasoconstriction, corresponding to hypoxemia. Computer simulation based on the inverse Monte Carlo method showed that hemoglobin oxygen saturation declined to as low as ∼35% in the long-term hypoxemic phase. Overall, we found that topical application of a shock wave to the brain caused spreading depolarization/depression and prolonged severe hypoxemia-oligemia, which might lead to pathological conditions in the brain. Although further study is needed, our findings suggest that spreading depolarization/depression is one of the key events determining the outcome in bTBI. Furthermore, a rat exposed to an LISW(s) can be a reliable laboratory animal model for blast injury research. PMID:24416150

Wave activity in the neighborhood of the bowshock of Mars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sagdeev, R.Z.; Shapiro, V.D.; Shevchenko, V.I.

Plasma wave activity in the neighborhood of the Martial bow shock were measured for the first time by the Soviet spacecraft Phobos-2 in a wide frequency range from dc to 150 kHz. The wave activity varied in character as the spacecraft moved across different plasma regions: in the neighborhood of the Martian bow shock, inside the magnetosheath and in the tail region. In this paper the authors provide suggestions for the processes responsible for these plasma waves. The most interesting peculiarities of the wave activity around Mars is the sharp increase of wave intensity in the magnetosheath region. This increasemore » is attributed to two different physical mechanisms. High frequency waves are excited at the shock front due to currents flowing along the front; these ion acoustic waves are convected inside by the solar wind. The low frequency waves ({approximately}100 Hz) close to the inside boundary were, they believe, generated by heavy Martian ions diffusing through the planetopause into the magnetosheath.« less

Cocaine action on peripheral, non-monoamine neural substrates as a trigger of EEG desynchronization and EMG activation following intravenous administration in freely moving rats

PubMed Central

Smirnov, Michael S.; Kiyatkin, Eugene A.

2009-01-01

Many important physiological, behavioral and subjective effects of intravenous (iv) cocaine (COC) are exceptionally rapid and transient, suggesting a possible involvement of peripheral neural substrates in their triggering. In the present study, we used high-speed EEG and EMG recordings (4-s resolution) in freely moving rats to characterize the central electrophysiological effects of iv COC at low doses within a self-administration range (0.25-1.0 mg/kg). We found that COC induces rapid, strong, and prolonged desynchronization of cortical EEG (decrease in alpha and increase in beta and gamma activity) and activation of the neck EMG that begin within 2-6 s following the start of a 10-s injection; immediate components of both effects were dose-independent. The rapid effects of COC were mimicked by iv COC methiodide, a derivative that cannot cross the blood-brain barrier. At equimolar doses (0.33-1.33 mg/kg), COC methiodide had equally fast and strong effects on EEG and EMG total powers, decreasing alpha and increasing beta and gamma activities. Rapid EEG desynchronization and EMG activation was also induced by iv procaine, a structurally similar, short-acting local anesthetic with virtually no effects on monoamine uptake; at equipotential doses (1.25-5.0 mg/kg), these effects were weaker and shorter in duration than those of COC. Surprisingly, iv saline injection delivered during slow-wave sleep (but not during quiet wakefulness) also induced a transient EEG desynchronization but without changes in EMG and motor activity; these effects were significantly weaker and much shorter than those induced by all tested drugs. These data suggest that in awake animals, iv COC induces rapid cortical activation and a subsequent motor response via its action on peripheral non-monoamine neural elements, involving neural transmission via visceral sensory pathways. By providing a rapid neural signal and triggering neural activation, such an action might play a crucial role in the sensory effects of COC, thus contributing to the learning and development of drug-taking behavior. PMID:19861149

Blood-Brain Barrier Breakdown Following Traumatic Brain Injury: A Possible Role in Posttraumatic Epilepsy

PubMed Central

Tomkins, Oren; Feintuch, Akiva; Benifla, Moni; Cohen, Avi; Friedman, Alon; Shelef, Ilan

2011-01-01

Recent animal experiments indicate a critical role for opening of the blood-brain barrier (BBB) in the pathogenesis of post-traumatic epilepsy (PTE). This study aimed to investigate the frequency, extent, and functional correlates of BBB disruption in epileptic patients following mild traumatic brain injury (TBI). Thirty-seven TBI patients were included in this study, 19 of whom suffered from PTE. All underwent electroencephalographic (EEG) recordings and brain magnetic resonance imaging (bMRI). bMRIs were evaluated for BBB disruption using novel quantitative techniques. Cortical dysfunction was localized using standardized low-resolution brain electromagnetic tomography (sLORETA). TBI patients displayed significant EEG slowing compared to controls with no significant differences between PTE and nonepileptic patients. BBB disruption was found in 82.4% of PTE compared to 25% of non-epileptic patients (P = .001) and could be observed even years following the trauma. The volume of cerebral cortex with BBB disruption was significantly larger in PTE patients (P = .001). Slow wave EEG activity was localized to the same region of BBB disruption in 70% of patients and correlated to the volume of BBB disrupted cortex. We finally present a patient suffering from early cortical dysfunction and BBB breakdown with a gradual and parallel resolution of both pathologies. Our findings demonstrate that BBB pathology is frequently found following mild TBI. Lasting BBB breakdown is found with increased frequency and extent in PTE patients. Based on recent animal studies and the colocalization found between the region of disrupted BBB and abnormal EEG activity, we suggest a role for a vascular lesion in the pathogenesis of PTE. PMID:21436875

Longitudinal sleep EEG trajectories indicate complex patterns of adolescent brain maturation.

PubMed

Feinberg, Irwin; Campbell, Ian G

2013-02-15

New longitudinal sleep data spanning ages 6-10 yr are presented and combined with previous data to analyze maturational trajectories of delta and theta EEG across ages 6-18 yr in non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. NREM delta power (DP) increased from age 6 to age 8 yr and then declined. Its highest rate of decline occurred between ages 12 and 16.5 yr. We attribute the delta EEG trajectories to changes in synaptic density. Whatever their neuronal underpinnings, these age curves can guide research into the molecular-genetic mechanisms that underlie adolescent brain development. The DP trajectories in NREM and REM sleep differed strikingly. DP in REM did not initially increase but declined steadily from age 6 to age 16 yr. We hypothesize that the DP decline in REM reflects maturation of the same brain arousal systems that eliminate delta waves in waking EEG. Whereas the DP age curves differed in NREM and REM sleep, theta age curves were similar in both, roughly paralleling the age trajectory of REM DP. The different maturational curves for NREM delta and theta indicate that they serve different brain functions despite having similar within-sleep dynamics and responses to sleep loss. Period-amplitude analysis of NREM and REM delta waveforms revealed that the age trends in DP were driven more by changes in wave amplitude rather than incidence. These data further document the powerful and complex link between sleep and brain maturation. Understanding this relationship would shed light on both brain development and the function of sleep.

Sporadic occurrence of completely lateralized vertex sharp transients of sleep is a normal phenomenon: a retrospective, blinded, case-control study.

PubMed

Brenton, J Nicholas; Mytinger, John R

2015-04-01

Vertex sharp transients (VSTs) of sleep often lateralize to the left or right frontocentral regions and can be mistaken as epileptiform. The aim of this study was to determine the prevalence of completely lateralized VSTs in pediatric-aged individuals and to assess their significance by comparing cohorts with and without epilepsy. The authors hypothesized that completely lateralized VSTs are normal and occur with similar frequencies in patients with and without epilepsy. The authors conducted a retrospective, blinded, case-control study comparing completely lateralized VSTs within a 5-minute EEG sleep epoch between cohorts of 100 patients with epilepsy and 100 age- and gender-matched controls. The number of patients with completely lateralized VSTs was not significantly different between cases (62%) and controls (65%) (P = 0.66). The median number of completely lateralized VSTs was small but not significantly different between cases (median 3) and controls (median 4) (P = 0.11). The presence of completely lateralized VSTs in cases (generalized vs. focal epilepsy) was not significantly different (P > 0.95). This is the first systematic study of the prevalence and significance of completely lateralized VSTs of sleep. This study provides class III evidence that completely lateralized VSTs, occurring in a sporadic fashion, are a normal phenomenon and should not be confused with epileptiform discharges.

Generation of Caustics and Rogue Waves from Nonlinear Instability.

PubMed

Safari, Akbar; Fickler, Robert; Padgett, Miles J; Boyd, Robert W

2017-11-17

Caustics are phenomena in which nature concentrates the energy of waves and may exhibit rogue-type behavior. Although they are known mostly in optics, caustics are intrinsic to all wave phenomena. As we demonstrate in this Letter, the formation of caustics and consequently rogue events in linear systems requires strong phase fluctuations. We show that nonlinear phase shifts can generate sharp caustics from even small fluctuations. Moreover, in that the wave amplitude increases dramatically in caustics, nonlinearity is usually inevitable. We perform an experiment in an optical system with Kerr nonlinearity, simulate the results based on the nonlinear Schrödinger equation, and achieve perfect agreement. As the same theoretical framework is used to describe other wave systems such as large-scale water waves, our results may also aid the understanding of ocean phenomena.

Shared Genetic Control of Brain Activity During Sleep and Insulin Secretion: A Laboratory-Based Family Study.

PubMed

Morselli, Lisa L; Gamazon, Eric R; Tasali, Esra; Cox, Nancy J; Van Cauter, Eve; Davis, Lea K

2018-01-01

Over the past 20 years, a large body of experimental and epidemiologic evidence has linked sleep duration and quality to glucose homeostasis, although the mechanistic pathways remain unclear. The aim of the current study was to determine whether genetic variation influencing both sleep and glucose regulation could underlie their functional relationship. We hypothesized that the genetic regulation of electroencephalographic (EEG) activity during non-rapid eye movement sleep, a highly heritable trait with fingerprint reproducibility, is correlated with the genetic control of metabolic traits including insulin sensitivity and β-cell function. We tested our hypotheses through univariate and bivariate heritability analyses in a three-generation pedigree with in-depth phenotyping of both sleep EEG and metabolic traits in 48 family members. Our analyses accounted for age, sex, adiposity, and the use of psychoactive medications. In univariate analyses, we found significant heritability for measures of fasting insulin sensitivity and β-cell function, for time spent in slow-wave sleep, and for EEG spectral power in the delta, theta, and sigma ranges. Bivariate heritability analyses provided the first evidence for a shared genetic control of brain activity during deep sleep and fasting insulin secretion rate. © 2017 by the American Diabetes Association.

Quantitative modeling of multiscale neural activity

NASA Astrophysics Data System (ADS)

Robinson, Peter A.; Rennie, Christopher J.

2007-01-01

The electrical activity of the brain has been observed for over a century and is widely used to probe brain function and disorders, chiefly through the electroencephalogram (EEG) recorded by electrodes on the scalp. However, the connections between physiology and EEGs have been chiefly qualitative until recently, and most uses of the EEG have been based on phenomenological correlations. A quantitative mean-field model of brain electrical activity is described that spans the range of physiological and anatomical scales from microscopic synapses to the whole brain. Its parameters measure quantities such as synaptic strengths, signal delays, cellular time constants, and neural ranges, and are all constrained by independent physiological measurements. Application of standard techniques from wave physics allows successful predictions to be made of a wide range of EEG phenomena, including time series and spectra, evoked responses to stimuli, dependence on arousal state, seizure dynamics, and relationships to functional magnetic resonance imaging (fMRI). Fitting to experimental data also enables physiological parameters to be infered, giving a new noninvasive window into brain function, especially when referenced to a standardized database of subjects. Modifications of the core model to treat mm-scale patchy interconnections in the visual cortex are also described, and it is shown that resulting waves obey the Schroedinger equation. This opens the possibility of classical cortical analogs of quantum phenomena.

Respiratory cycle-related electroencephalographic changes during sleep in healthy children and in children with sleep disordered breathing.

PubMed

Immanuel, Sarah A; Pamula, Yvonne; Kohler, Mark; Martin, James; Kennedy, Declan; Saint, David A; Baumert, Mathias

2014-08-01

To investigate respiratory cycle-related electroencephalographic changes (RCREC) in healthy children and in children with sleep disordered breathing (SDB) during scored event-free (SEF) breathing periods of sleep. Interventional case-control repeated measurements design. Paediatric sleep laboratory in a hospital setting. Forty children with SDB and 40 healthy, age- and sex-matched children. Adenotonsillectomy in children with SDB and no intervention in controls. Overnight polysomnography; electroencephalography (EEG) power variations within SEF respiratory cycles in the overall and frequency band-specific EEG within stage 2 nonrapid eye movement (NREM) sleep, slow wave sleep (SWS), and rapid eye movement (REM) sleep. Within both groups there was a decrease in EEG power during inspiration compared to expiration across all sleep stages. Compared to controls, RCREC in children with SDB in the overall EEG were significantly higher during REM and frequency band specific RCRECs were higher in the theta band of stage 2 and REM sleep, alpha band of SWS and REM sleep, and sigma band of REM sleep. This between-group difference was not significant postadenotonsillectomy. The presence of nonrandom respiratory cycle-related electroencephalographic changes (RCREC) in both healthy children and in children with sleep disordered breathing (SDB) during NREM and REM sleep has been demonstrated. The RCREC values were higher in children with SDB, predominantly in REM sleep and this difference reduced after adenotonsillectomy. Immanuel SA, Pamula Y, Kohler M, Martin J, Kennedy D, Saint DA, Baumert M. Respiratory cycle-related electroencephalographic changes during sleep in healthy children and in children with sleep disordered breathing.

Automatic characterization of sleep need dissipation dynamics using a single EEG signal.

PubMed

Garcia-Molina, Gary; Bellesi, Michele; Riedner, Brady; Pastoor, Sander; Pfundtner, Stefan; Tononi, Giulio

2015-01-01

In the two-process model of sleep regulation, slow-wave activity (SWA, i.e. the EEG power in the 0.5-4 Hz frequency band) is considered a direct indicator of sleep need. SWA builds up during non-rapid eye movement (NREM) sleep, declines before the onset of rapid-eye-movement (REM) sleep, remains low during REM and the level of increase in successive NREM episodes gets progressively lower. Sleep need dissipates with a speed that is proportional to SWA and can be characterized in terms of the initial sleep need, and the decay rate. The goal in this paper is to automatically characterize sleep need from a single EEG signal acquired at a frontal location. To achieve this, a highly specific and reasonably sensitive NREM detection algorithm is proposed that leverages the concept of a single-class Kernel-based classifier. Using automatic NREM detection, we propose a method to estimate the decay rate and the initial sleep need. This method was tested on experimental data from 8 subjects who recorded EEG during three nights at home. We found that on average the estimates of the decay rate and the initial sleep need have higher values when automatic NREM detection was used as compared to manual NREM annotation. However, the average variability of these estimates across multiple nights of the same subject was lower when the automatic NREM detection classifier was used. While this method slightly over estimates the sleep need parameters, the reduced variability across subjects makes it more effective for within subject statistical comparisons of a given sleep intervention.

Plastic changes following imitation-based speech and language therapy for aphasia: a high-density sleep EEG study.

PubMed

Sarasso, Simone; Määttä, Sara; Ferrarelli, Fabio; Poryazova, Rositsa; Tononi, Giulio; Small, Steven L

2014-02-01

BACKGROUND OBJECTIVE: measurement of plastic brain changes induced by a novel rehabilitative approach is a key requirement for validating its biological rationale linking the potential therapeutic gains to the changes in brain physiology. Based on an emerging notion linking cortical plastic changes to EEG sleep slow-wave activity (SWA) regulation, we aimed to assess the acute plastic changes induced by an imitation-based speech therapy in individuals with aphasia by comparing sleep SWA changes before and after therapy. A total of 13 left-hemispheric stroke patients underwent language assessment with the Western Aphasia Battery (WAB) before and after 2 consecutive high-density (hd) EEG sleep recordings interleaved by a daytime session of imitation-based speech therapy (Intensive Mouth Imitation and Talking for Aphasia Therapeutic Effects [IMITATE]). This protocol is thought to stimulate bilateral connections between the inferior parietal lobule and the ventral premotor areas. A single exposure to IMITATE resulted in increases in local EEG SWA during subsequent sleep over the same regions predicted by the therapeutic rationale, particularly over the right hemisphere (unaffected by the lesion). Furthermore, changes in SWA over the left-precentral areas predicted changes in WAB repetition scores in our group, supporting the role of perilesional areas in predicting positive functional responses. Our results suggest that SWA changes occurring in brain areas activated during imitation-based aphasia therapy may reflect the acute plastic changes induced by this intervention. Further testing will be needed to evaluate SWA as a non-invasive assessment of changes induced by the therapy and as a predictor of positive long-term clinical outcome.

Blindfolding during wakefulness causes decrease in sleep slow wave activity.

PubMed

Korf, Eva Magdalena; Mölle, Matthias; Born, Jan; Ngo, Hong-Viet V

2017-04-01

Slow wave activity (SWA, 0.5-4 Hz) represents the predominant EEG oscillatory activity during slow wave sleep (SWS). Its amplitude is considered in part a reflection of synaptic potentiation in cortical networks due to encoding of information during prior waking, with higher amplitude indicating stronger potentiation. Previous studies showed that increasing and diminishing specific motor behaviors produced corresponding changes in SWA in the respective motor cortical areas during subsequent SWS Here, we tested whether this relationship can be generalized to the visual system, that is, whether diminishing encoding of visual information likewise leads to a localized decrease in SWA over the visual cortex. Experiments were performed in healthy men whose eyes on two different days were or were not covered for 10.5 h before bedtime. The subject's EEG was recorded during sleep and, after sleep, visual evoked potentials (VEPs) were recorded. SWA during nonrapid eye movement sleep (NonREM sleep) was lower after blindfolding than after eyes open ( P  < 0.01). The decrease in SWA that was most consistent during the first 20 min of NonREM sleep, did not remain restricted to visual cortex regions, with changes over frontal and parietal cortical regions being even more pronounced. In the morning after sleep, the N75-P100 peak-to-peak-amplitude of the VEP was significantly diminished in the blindfolded condition. Our findings confirm a link between reduced wake encoding and diminished SWA during ensuing NonREM sleep, although this link appears not to be restricted to sensory cortical areas. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Generation of Caustics and Rogue Waves from Nonlinear Instability

NASA Astrophysics Data System (ADS)

Safari, Akbar; Fickler, Robert; Padgett, Miles J.; Boyd, Robert W.

2017-11-01

Caustics are phenomena in which nature concentrates the energy of waves and may exhibit rogue-type behavior. Although they are known mostly in optics, caustics are intrinsic to all wave phenomena. As we demonstrate in this Letter, the formation of caustics and consequently rogue events in linear systems requires strong phase fluctuations. We show that nonlinear phase shifts can generate sharp caustics from even small fluctuations. Moreover, in that the wave amplitude increases dramatically in caustics, nonlinearity is usually inevitable. We perform an experiment in an optical system with Kerr nonlinearity, simulate the results based on the nonlinear Schrödinger equation, and achieve perfect agreement. As the same theoretical framework is used to describe other wave systems such as large-scale water waves, our results may also aid the understanding of ocean phenomena.

Midline thalamic neurons are differentially engaged during hippocampus network oscillations.

PubMed

Lara-Vásquez, Ariel; Espinosa, Nelson; Durán, Ernesto; Stockle, Marcelo; Fuentealba, Pablo

2016-07-14

The midline thalamus is reciprocally connected with the medial temporal lobe, where neural circuitry essential for spatial navigation and memory formation resides. Yet, little information is available on the dynamic relationship between activity patterns in the midline thalamus and medial temporal lobe. Here, we report on the functional heterogeneity of anatomically-identified thalamic neurons and the differential modulation of their activity with respect to dorsal hippocampal rhythms in the anesthetized mouse. Midline thalamic neurons expressing the calcium-binding protein calretinin, irrespective of their selective co-expression of calbindin, discharged at overall low levels, did not increase their activity during hippocampal theta oscillations, and their firing rates were inhibited during hippocampal sharp wave-ripples. Conversely, thalamic neurons lacking calretinin discharged at higher rates, increased their activity during hippocampal theta waves, but remained unaffected during sharp wave-ripples. Our results indicate that the midline thalamic system comprises at least two different classes of thalamic projection neuron, which can be partly defined by their differential engagement by hippocampal pathways during specific network oscillations that accompany distinct behavioral contexts. Thus, different midline thalamic neuronal populations might be selectively recruited to support distinct stages of memory processing, consistent with the thalamus being pivotal in the dialogue of cortical circuits.

[EFFECTS OF ELECTRICAL STIMULATION OF NUCLEUS RETICULARIS PONTIS ORALIS ON THE SLEEP-WAKING STATES IN KRUSHINSKII-MOLODKINA STRAIN RATS].

PubMed

Vataev, S I; Malgina, N A; Oganesyan, G A

2015-07-01

The effects of electrical stimulation of nucleus reticularis pontis oralis on the behavior and brain electrical activity during all phases of the sleep-waking cycle was studied in Krushinskii-Molodkina strain rats, which have an inherited predisposition to audiogenic seizures. Electrical stimulation with 7 Hz frequency in the deep stage of slow-wave sleep cause appearance the fast-wave sleep. Similar stimulation during fast-wave sleep periods did not effects on the electrographic patterns and EEG spectral characteristics of hippocampus, visual, auditory and somatocnen nrnrenc nf the cnrtey ThPe sfimul1stinns did nnt break a fast-wave sleenhut increased almost twice due the duration of these sleep episodes. After electrical stimulation by same frequency during the wakeftlness and superficial slow-wave sleep states, the patterns and spectral characteristics of brain electrical activity in rats showed no significant changes as compared with controls. The results of this study indicate that the state of the animals sleep-waking cycle at the time of stimulation is a critical variable that influences the responses which are induced by electrical stimulation of the nucleus reticularis pontis oralis.

Computational and experimental investigation of two-dimensional scramjet inlets and hypersonic flow over a sharp flat plate

NASA Astrophysics Data System (ADS)

Messitt, Donald G.

1999-11-01

The WIND code was employed to compute the hypersonic flow in the shock wave boundary layer merged region near the leading edge of a sharp flat plate. Solutions were obtained at Mach numbers from 9.86 to 15.0 and free stream Reynolds numbers of 3,467 to 346,700 in-1 (1.365 · 105 to 1.365 · 107 m-1) for perfect gas conditions. The numerical results indicated a merged shock wave and viscous layer near the leading edge. The merged region grew in size with increasing free stream Mach number, proportional to Minfinity 2/Reinfinity. Profiles of the static pressure in the merged region indicated a strong normal pressure gradient (∂p/∂y). The normal pressure gradient has been neglected in previous analyses which used the boundary layer equations. The shock wave near the leading edge was thick, as has been experimentally observed. Computed shock wave locations and surface pressures agreed well within experimental error for values of the rarefaction parameter, chi/M infinity2 < 0.3. A preliminary analysis using kinetic theory indicated that rarefied flow effects became important above this value. In particular, the WIND solution agreed well in the transition region between the merged flow, which was predicted well by the theory of Li and Nagamatsu, and the downstream region where the strong interaction theory applied. Additional computations with the NPARC code, WIND's predecessor, demonstrated the ability of the code to compute hypersonic inlet flows at free stream Mach numbers up to 20. Good qualitative agreement with measured pressure data indicated that the code captured the important physical features of the shock wave - boundary layer interactions. The computed surface and pitot pressures fell within the combined experimental and numerical error bounds for most points. The calculations demonstrated the need for extremely fine grids when computing hypersonic interaction flows.

Optogenetically Blocking Sharp Wave Ripple Events in Sleep Does Not Interfere with the Formation of Stable Spatial Representation in the CA1 Area of the Hippocampus

PubMed Central

Kovács, Krisztián A.; O’Neill, Joseph; Schoenenberger, Philipp; Penttonen, Markku; Ranguel Guerrero, Damaris K.; Csicsvari, Jozsef

2016-01-01

During hippocampal sharp wave/ripple (SWR) events, previously occurring, sensory input-driven neuronal firing patterns are replayed. Such replay is thought to be important for plasticity-related processes and consolidation of memory traces. It has previously been shown that the electrical stimulation-induced disruption of SWR events interferes with learning in rodents in different experimental paradigms. On the other hand, the cognitive map theory posits that the plastic changes of the firing of hippocampal place cells constitute the electrophysiological counterpart of the spatial learning, observable at the behavioral level. Therefore, we tested whether intact SWR events occurring during the sleep/rest session after the first exploration of a novel environment are needed for the stabilization of the CA1 code, which process requires plasticity. We found that the newly-formed representation in the CA1 has the same level of stability with optogenetic SWR blockade as with a control manipulation that delivered the same amount of light into the brain. Therefore our results suggest that at least in the case of passive exploratory behavior, SWR-related plasticity is dispensable for the stability of CA1 ensembles. PMID:27760158

Hydro morphodynamic modelling in Mediterranean storms: errors and uncertainties under sharp gradients

NASA Astrophysics Data System (ADS)

Sánchez-Arcilla, A.; Gracia, V.; García, M.

2014-02-01

This paper deals with the limits in hydrodynamic and morphodynamic predictions for semi-enclosed coastal domains subject to sharp gradients (in bathymetry, topography, sediment transport and coastal damages). It starts with an overview of wave prediction limits (based on satellite images) in a restricted domain such as is the Mediterranean basin, followed by an in-depth analysis of the Catalan coast, one of the land boundaries of such a domain. The morphodynamic modeling for such gradient regions is next illustrated with the simulation of the largest recorded storm in the Catalan coast, whose morphological impact is a key element of the storm impact. The driving wave and surge conditions produce a morphodynamic response that is validated against the pre and post storm beach state, recovered from two LIDAR images. The quality of the fit is discussed in terms of the physical processes and the suitability of the employed modeling equations. Some remarks about the role of the numerical discretization and boundary conditions are also included in the analysis. From here an assessment of errors and uncertainties is presented, with the aim of establishing the prediction limits for coastal engineering flooding and erosion analyses.

On increasing stability in the two dimensional inverse source scattering problem with many frequencies

NASA Astrophysics Data System (ADS)

Entekhabi, Mozhgan Nora; Isakov, Victor

2018-05-01

In this paper, we will study the increasing stability in the inverse source problem for the Helmholtz equation in the plane when the source term is assumed to be compactly supported in a bounded domain Ω with a sufficiently smooth boundary. Using the Fourier transform in the frequency domain, bounds for the Hankel functions and for scattering solutions in the complex plane, improving bounds for the analytic continuation, and the exact observability for the wave equation led us to our goals which are a sharp uniqueness and increasing stability estimate when the wave number interval is growing.

Enhanced Slow-Wave EEG Activity and Thermoregulatory Impairment following the Inhibition of the Lateral Hypothalamus in the Rat

PubMed Central

Cerri, Matteo; Vecchio, Flavia Del; Mastrotto, Marco; Luppi, Marco; Martelli, Davide; Perez, Emanuele; Tupone, Domenico; Zamboni, Giovanni; Amici, Roberto

2014-01-01

Neurons within the lateral hypothalamus (LH) are thought to be able to evoke behavioural responses that are coordinated with an adequate level of autonomic activity. Recently, the acute pharmacological inhibition of LH has been shown to depress wakefulness and promote NREM sleep, while suppressing REM sleep. These effects have been suggested to be the consequence of the inhibition of specific neuronal populations within the LH, i.e. the orexin and the MCH neurons, respectively. However, the interpretation of these results is limited by the lack of quantitative analysis of the electroencephalographic (EEG) activity that is critical for the assessment of NREM sleep quality and the presence of aborted NREM-to-REM sleep transitions. Furthermore, the lack of evaluation of the autonomic and thermoregulatory effects of the treatment does not exclude the possibility that the wake-sleep changes are merely the consequence of the autonomic, in particular thermoregulatory, changes that may follow the inhibition of LH neurons. In the present study, the EEG and autonomic/thermoregulatory effects of a prolonged LH inhibition provoked by the repeated local delivery of the GABAA agonist muscimol were studied in rats kept at thermoneutral (24°C) and at a low (10°C) ambient temperature (Ta), a condition which is known to depress sleep occurrence. Here we show that: 1) at both Tas, LH inhibition promoted a peculiar and sustained bout of NREM sleep characterized by an enhancement of slow-wave activity with no NREM-to-REM sleep transitions; 2) LH inhibition caused a marked transitory decrease in brain temperature at Ta 10°C, but not at Ta 24°C, suggesting that sleep changes induced by LH inhibition at thermoneutrality are not caused by a thermoregulatory impairment. These changes are far different from those observed after the short-term selective inhibition of either orexin or MCH neurons, suggesting that other LH neurons are involved in sleep-wake modulation. PMID:25398141

Insufficient non-REM sleep intensity in narcolepsy-cataplexy.

PubMed

Khatami, Ramin; Landolt, Hans-Peter; Achermann, Peter; Rétey, Julia V; Werth, Esther; Mathis, Johannes; Bassetti, Claudio L

2007-08-01

To compare electroencephalogram (EEG) dynamics during nocturnal sleep in patients with narcolepsy-cataplexy and healthy controls. Fragmented nocturnal sleep is a prominent feature and contributes to excessive daytime sleepiness in narcolepsy-cataplexy. Only 3 studies have addressed changes in homeostatic sleep regulation as a possible mechanism underlying nocturnal sleep fragmentation in narcolepsy-cataplexy. Baseline sleep of 11 drug-naive patients with narcolepsy-cataplexy (19-37 years) and 11 matched controls (18-41 years) was polysomnographically recorded. The EEG was subjected to spectral analysis. None, baseline condition. All patients with narcolepsy-cataplexy but no control subjects showed a sleep-onset rapid eye movement (REM) episode. Non-REM (NREM)-REM sleep cycles were longer in patients with narcolepsy-cataplexy than in controls (P = 0.04). Mean slow-wave activity declined in both groups across the first 3 NREM sleep episodes (P<0.001). The rate of decline, however, appeared to be steeper in patients with narcolepsy-cataplexy (time constant: narcolepsy-cataplexy 51.1 +/- 23.8 minutes [mean +/- SEM], 95% confidence interval [CI]: 33.4-108.8 minutes) than in controls (169.4 +/- 81.5 minutes, 95% CI: 110.9-357.6 minutes) as concluded from nonoverlapping 95% confidence interval of the time constants. The steeper decline of SWA in narcolepsy-cataplexy compared to controls was related to an impaired build-up of slow-wave activity in the second cycle. Sleep in the second cycle was interrupted in patients with narcolepsy-cataplexy, when compared with controls, by an increased number (P = 0.01) and longer duration (P = 0.01) of short wake episodes. Insufficient NREM sleep intensity is associated with nonconsolidated nocturnal sleep in narcolepsy-cataplexy. The inability to consolidate sleep manifests itself when NREM sleep intensity has decayed below a certain level and is reflected in an altered time course of slow-wave activity across NREM sleep episodes.

Source analysis of MEG activities during sleep (abstract)

NASA Astrophysics Data System (ADS)

Ueno, S.; Iramina, K.

1991-04-01

The present study focuses on magnetic fields of the brain activities during sleep, in particular on K-complexes, vertex waves, and sleep spindles in human subjects. We analyzed these waveforms based on both topographic EEG (electroencephalographic) maps and magnetic fields measurements, called MEGs (magnetoencephalograms). The components of magnetic fields perpendicular to the surface of the head were measured using a dc SQUID magnetometer with a second derivative gradiometer. In our computer simulation, the head is assumed to be a homogeneous spherical volume conductor, with electric sources of brain activity modeled as current dipoles. Comparison of computer simulations with the measured data, particularly the MEG, suggests that the source of K-complexes can be modeled by two current dipoles. A source for the vertex wave is modeled by a single current dipole which orients along the body axis out of the head. By again measuring the simultaneous MEG and EEG signals, it is possible to uniquely determine the orientation of this dipole, particularly when it is tilted slightly off-axis. In sleep stage 2, fast waves of magnetic fields consistently appeared, but EEG spindles appeared intermittently. The results suggest that there exist sources which are undetectable by electrical measurement but are detectable by magnetic-field measurement. Such source can be described by a pair of opposing dipoles of which directions are oppositely oriented.

[Features of seasonal reorganizations of the central mechanisms of regulation in children northerners with different level of social risk].

PubMed

Soroko, S I; Rozhkov, V P; Bekshaev, S S

2013-12-01

The paper presents a comparative analysis of frequency, spatial-temporal parameters and three-dimensional localization of EEG sources that characterize changes of cortical-subcortical interactions processes in autumn and spring periods at northern schoolchildren living in satisfactory and disadvantaged (risk group) conditions of the social (family) environment. Seasonal rearrangement of interaction between wave components of main EEG rhythms was revealed. School students present regressive changes in the EEG pattern temporal organization in spring compared to autumn, and this effect was more expressed at adolescents from group of risk. Data EEDS-tomography showed increased activity in the prefrontal, cingular and subcallosal areas of the cortex in the autumn period that could be related to the mechanisms of season depression caused by the significant reduction of the day length in the North. The increased activity of the limbic system structures which is persisted in the spring in adolescents from risk group narrows the range of regulation of adaptive reactions. Unfavorable conditions of the family environment are an additional stress factor to increased load on the regulatory mechanisms that have a negative impact on the emotional-motivation behavior of children and adolescents, thus increasing the risk of the school and of social disadaptation.

Conformal mapping for the Helmholtz equation: acoustic wave scattering by a two dimensional inclusion with irregular shape in an ideal fluid.

PubMed

Liu, Gang; Jayathilake, Pahala G; Khoo, Boo Cheong; Han, Feng; Liu, Dian Kui

2012-02-01

The complex variables method with mapping function was extended to solve the linear acoustic wave scattering by an inclusion with sharp/smooth corners in an infinite ideal fluid domain. The improved solutions of Helmholtz equation, shown as Bessel function with mapping function as the argument and fractional order Bessel function, were analytically obtained. Based on the mapping function, the initial geometry as well as the original physical vector can be transformed into the corresponding expressions inside the mapping plane. As all the physical vectors are calculated in the mapping plane (η,η), this method can lead to potential vast savings of computational resources and memory. In this work, the results are validated against several published works in the literature. The different geometries of the inclusion with sharp corners based on the proposed mapping functions for irregular polygons are studied and discussed. The findings show that the variation of angles and frequencies of the incident waves have significant influence on the bistatic scattering pattern and the far-field form factor for the pressure in the fluid. © 2012 Acoustical Society of America

Head direction cells in the postsubiculum do not show replay of prior waking sequences during sleep

PubMed Central

Brandon, Mark P.; Bogaard, Andrew; Andrews, Chris M.; Hasselmo, Michael E.

2011-01-01

During slow-wave sleep and REM sleep, hippocampal place cells in the rat show replay of sequences previously observed during waking. We tested the hypothesis from computational modelling that the temporal structure of REM sleep replay could arise from an interplay of place cells with head direction cells in the postsubiculum. Physiological single-unit recording was performed simultaneously from five or more head direction or place by head direction cells in the postsubiculum during running on a circular track allowing sampling of a full range of head directions, and during sleep periods before and after running on the circular track. Data analysis compared the spiking activity during individual REM periods with waking as in previous analysis procedures for REM sleep. We also used a new procedure comparing groups of similar runs during waking with REM sleep periods. There was no consistent evidence for a statistically significant correlation of the temporal structure of spiking during REM sleep with spiking during waking running periods. Thus, the spiking activity of head direction cells during REM sleep does not show replay of head direction cell activity occurring during a previous waking period of running on the task. In addition, we compared the spiking of postsubiculum neurons during hippocampal sharp wave ripple events. We show that head direction cells are not activated during sharp wave ripples, while neurons responsive to place in the postsubiculum show reliable spiking at ripple events. PMID:21509854

Development and Application of PIV in Supersonic flows

NASA Astrophysics Data System (ADS)

Rong, Z.; Liu, H.; Chen, F.

2011-09-01

This paper presents PIV measurements obtained in Mach 4.0 flowfields performed in the SJTU Hypersonic wind tunnel (HWT). In order to certificate this technique, PIV experiments were conducted to the empty test section to provide uniform flow data for comparison with analysis data. Dynamical properties of particle tracers were investigated to measure the particle response across an oblique shock wave. The flow over a sharp cone at Ma = 4.0 were tested in comparasion with the CFD and schlieren visualization. It is shown that shock wave angles measured with PIV are in good agreement with theory and schlieren visualization, in addition the overall flow is consistent with the CFD results.

Sleep Homeostatic and Waking Behavioral Phenotypes in Egr3-Deficient Mice Associated with Serotonin Receptor 5-HT2 Deficits

PubMed Central

Grønli, Janne; Clegern, William C.; Schmidt, Michelle A.; Nemri, Rahmi S.; Rempe, Michael J.; Gallitano, Amelia L.; Wisor, Jonathan P.

2016-01-01

Study Objective: The expression of the immediate early gene early growth response 3 (Egr3) is a functional marker of brain activity including responses to novelty, sustained wakefulness, and sleep. We examined the role of this gene in regulating wakefulness and sleep. Methods: Electroencephalogram/electromyogram (EEG/EMG) were recorded in Egr3-/- and wild-type (WT) mice during 24 h baseline, 6 h sleep disruption and 6 h recovery. Serotonergic signaling was assessed with 6 h EEG/EMG recordings after injections of nonselective 5-HT2 antagonist (clozapine), selective 5-HT2 antagonists (5-HT2A; MDL100907 and 5-HT2BC; SB206553) and a cocktail of both selective antagonists, administered in a randomized order to each animal. Results: Egr3-/- mice did not exhibit abnormalities in the timing of wakefulness and slow wave sleep (SWS); however, EEG dynamics in SWS (suppressed 1–3 Hz power) and in quiet wakefulness (elevated 3–8 Hz and 15–35 Hz power) differed in comparison to WT-mice. Egr3-/- mice showed an exaggerated response to sleep disruption as measured by active wakefulness, but with a blunted increase in homeostatic sleep drive (elevated 1–4 Hz power) relative to WT-mice. Egr3-/-mice exhibit greatly reduced sedative effects of clozapine at the electroencephalographic level. In addition, clozapine induced a previously undescribed dissociated state (low amplitude, low frequency EEG and a stable, low muscle tone) lasting up to 2 h in WT-mice. Egr3-/- mice did not exhibit this phenomenon. Selective 5-HT2A antagonist, alone or in combination with selective 5-HT2BC antagonist, caused EEG slowing coincident with behavioral quiescence in WT-mice but not in Egr3-/- mice. Conclusion: Egr3 has an essential role in regulating cortical arousal, wakefulness, and sleep, presumably by its regulation of 5-HT2 receptors. Citation: Grønli J, Clegern WC, Schmidt MA, Nemri RS, Rempe MJ, Gallitano AL, Wisor JP. Sleep homeostatic and waking behavioral phenotypes in Egr3-deficient mice associated with serotonin receptor 5-HT2 deficits. SLEEP 2016;39(12):2189–2199. PMID:28057087

Effects of light on responses to low atmospheric pressure stunning in broilers.

PubMed

Martin, J E; Christensen, K; Vizzier-Thaxton, Y; McKeegan, D E F

2016-10-01

Low atmospheric pressure stunning (LAPS) is a novel approach to poultry stunning involving the application of gradual decompression lasting 280 s according to a prescribed pressure curve. The aim of this study was to determine how behavioural, electroencephalogram (EEG) and electrocardiogram (ECG) responses to LAPS are influenced by illumination of the decompression chamber. A secondary aim was to examine responses to the decompression chamber without LAPS being applied, as such a "sham" control has been absent in previous studies. A two by two factorial design was employed, with LAPS/light, LAPS/dark, sham/light and sham/dark treatments (N = 20 per treatment). Broilers were exposed to each treatment in pairs, in each of which one bird was instrumented for recording EEG and ECG. Illumination was applied at 500 lx, and in sham treatments, birds were identically handled but remained undisturbed in the LAPS chamber without decompression for 280 s. Birds which underwent the sham treatment exhibited behaviours which were also observed in LAPS (e.g. sitting) while those exposed to LAPS exhibited hypoxia-related behaviours (e.g. ataxia, loss of posture). Behavioural latencies and durations were increased in the sham treatments, since the whole cycle time was available (in LAPS; birds were motionless by 186 s). Within the sham treatments, illumination increased active behaviour and darkness induced sleep, but slow-wave EEG was seen in both. The pattern of EEG response to LAPS (steep reduction in median frequency in the first 60 s and increased total power) was similar, irrespective of illumination, though birds in darkness had shorter latencies to loss of consciousness and isoelectric EEG. Cardiac responses to LAPS (pronounced bradycardia) closely matched those reported previously and were not affected by illumination. The effects of LAPS/sham treatment primarily reflected the presence/absence of hypoxia, while illumination affected activity/sleep levels in sham-treated birds and slowed time to unconsciousness in birds undergoing LAPS. Therefore, it is recommended that LAPS be conducted in darkness for poultry.

Theoretical Investigation of 3-D Shock Wave-Turbulent Boundary Layer Interactions. Part 7

DTIC Science & Technology

1988-11-15

Particle traces - y/= 1.0 (80 SFC) 1 18II I I l U0 Flow .>4 .16. on Ange 8deg -5.0 9.81 24.6 39.4 54,2 69.0 0.1 N....,..X (b) CaseFG n Angle =8 dog . (a...generated by a sharp fin geometry. Both porn - zyada tries chosmn are ’d-mensouess’ and the interactions in the rij is the stress tensor (laminar + turbulent

Electron Density Dropout Near Enceladus in the Context of Water-Vapor and Water-Ice

NASA Technical Reports Server (NTRS)

Farrell, W. M.; Kurth, W. S.; Gurnett, D. A.; Johnson, R. E.; Kaiser, M. L.; Wahlund, J.-E.; Waite, J. H., Jr.

2009-01-01

On 12 March 2008, the Cassini spacecraft made a close encounter with the Saturnian moon Enceladus, passing within 52 km of the moon. The spacecraft trajectory was intentionally-oriented in a southerly direction to create a close alignment with the intense water-dominated plumes emitted from the south polar region. During the passage, the Cassini Radio and Plasma Wave System (RPWS) detected two distinct radio signatures: 1) Impulses associated with small water-ice dust grain impacts and 2) an upper hybrid (UH) resonance emission that both intensified and displayed a sharp frequency decrease in the near-vicinity of the moon. The frequency decrease of the UH emission is associated with an unexpectedly sharp decrease in electron density from approximately 90 el/cubic cm to below 20 el/cubic cm that occurs on a time scale of a minute near the closest encounter with the moon. In this work, we consider a number of scenarios to explain this sharp electron dropout, but surmise that electron absorption by ice grains is the most likely process.

Super-focusing of center-covered engineered microsphere

PubMed Central

Wu, Mengxue; Chen, Rui; Soh, Jiahao; Shen, Yue; Jiao, Lishi; Wu, Jianfeng; Chen, Xudong; Ji, Rong; Hong, Minghui

2016-01-01

Engineered microsphere possesses the advantage of strong light manipulation at sub-wavelength scale and emerges as a promising candidate to shrink the focal spot size. Here we demonstrated a center-covered engineered microsphere which can adjust the transverse component of the incident beam and achieve a sharp photonic nanojet. Modification of the beam width and working distance of the photonic nanojet were achieved by tuning the cover ratio of the engineered microsphere, leading to a sharp spot size which exceeded the optical diffraction limit. At a wavelength of 633 nm, a focal spot of 245 nm (0.387 λ) was achieved experimentally under plane wave illumination. Strong localized field with Bessel-like distribution was demonstrated by employing the linearly polarized beam and a center-covered mask being engineered on the microsphere. PMID:27528093

Skin-electrode impedance measurement during ECG acquisition: method’s validation

NASA Astrophysics Data System (ADS)

Casal, Leonardo; La Mura, Guillermo

2016-04-01

Skm-electrode impedance measurement can provide valuable information prior. dunng and post electrocardiographic (ECG) or electroencephalographs (EEG) acquisitions. In this work we validate a method for skm-electrode impedance measurement using test circuits with known resistance and capacitor values, at different frequencies for injected excitation current. Finally the method is successfully used for impedance measurement during ECG acquisition on a subject usmg 125 Hz and 6 nA square wave excitation signal at instrumentation amplifier mput. The method can be used for many electrodes configuration.

Computational analysis of blunt, thin airfoil sections at supersonic and subsonic speeds

NASA Astrophysics Data System (ADS)

Goodsell, Aga Myung

The past decade has brought renewed interest in commercial supersonic aircraft design. Recent wing designs have included regions of low sweep resulting in supersonic leading edges at cruise. Thin biconvex sections are used in those regions to minimize wave drag and skin-friction drag. However, airfoil sections with sharp leading edges exhibit poor aerodynamic behavior at subsonic flight conditions. Blunt leading edges may improve performance by delaying the onset of separation at subsonic and transonic speeds. Their disadvantage is that they increase both wave drag, due to the formation of a detached bow wave, and skin-friction drag, from a loss of laminar flow. The effect of adding bluntness to a 4%-thick biconvex section was investigated using computational analysis tools. The aerodynamic performance of biconvex sections with circular leading edges was computed at supersonic, transonic, and takeoff conditions. At supersonic cruise, the increase in wave drag due to bluntness is a function of Mach number and leading-edge diameter. Some of the drag penalty is offset by the suction created downstream of the circular leading edge. The possibility of further drag reduction was explored with the development of a semi-analytical method to design blunt airfoil shapes which minimize wave drag. The effect on the transition location was evaluated using linear stability analyses of laminar boundary-layer profiles and the eN method. The analysis showed that laminar boundary layers on blunt airfoil sections are considerably less stable to Tollmien-Schlichting waves than that on a sharp biconvex. At transonic speeds, the results suggest a possible improvement in the lift-to-drag ratio over a limited range of angles of attack. At the takeoff condition, slight blunting of the leading edge does improve the lift-to-drag ratio at low angles of attack, but has little effect on maximum lift. It is concluded that the benefit of a blunt leading edge at off-design conditions is not sufficient to warrant the resulting drag penalty at supersonic cruise. Furthermore, if maintaining laminar flow is critical to the design and some bluntness is necessary for manufacturing purposes, then the leading-edge diameter should be minimized to prevent transition and to reduce wave drag.

Marked surface inversions and wind shear: A safety risk for departing aircraft

NASA Technical Reports Server (NTRS)

Korhonen, O.

1983-01-01

Marked surface inversions occur most frequently in dry continental climates, where low atmospheric humidity allows heat transfer by long wave thermal radiation. In the northern latitudes, surface inversions reach their maximum intensity during the winter, when the incoming Sun's radiation is negligible and radiative cooling is dominant during the long nights. During winter, air mass boundaries are sharp, which causes formation of marked surface inversions. The existence of these inversions and sharp boundaries increase the risk of wind shear. The information should refer to marked inversions exceeding a temperature difference of 10 deg C up to 1000 feet. The need to determine the temperature range over which he information is operationally needed and the magnitude of the inversion required before a notification to pilots prior to departure is warranted are outlined.

Super-focusing of center-covered engineered microsphere.

PubMed

Wu, Mengxue; Chen, Rui; Soh, Jiahao; Shen, Yue; Jiao, Lishi; Wu, Jianfeng; Chen, Xudong; Ji, Rong; Hong, Minghui

2016-08-16

Engineered microsphere possesses the advantage of strong light manipulation at sub-wavelength scale and emerges as a promising candidate to shrink the focal spot size. Here we demonstrated a center-covered engineered microsphere which can adjust the transverse component of the incident beam and achieve a sharp photonic nanojet. Modification of the beam width and working distance of the photonic nanojet were achieved by tuning the cover ratio of the engineered microsphere, leading to a sharp spot size which exceeded the optical diffraction limit. At a wavelength of 633 nm, a focal spot of 245 nm (0.387 λ) was achieved experimentally under plane wave illumination. Strong localized field with Bessel-like distribution was demonstrated by employing the linearly polarized beam and a center-covered mask being engineered on the microsphere.

Resting-state beta and gamma activity in Internet addiction.

PubMed

Choi, Jung-Seok; Park, Su Mi; Lee, Jaewon; Hwang, Jae Yeon; Jung, Hee Yeon; Choi, Sam-Wook; Kim, Dai Jin; Oh, Sohee; Lee, Jun-Young

2013-09-01

Internet addiction is the inability to control one's use of the Internet and is related to impulsivity. Although a few studies have examined neurophysiological activity as individuals with Internet addiction engage in cognitive processing, no information on spontaneous EEG activity in the eyes-closed resting-state is available. We investigated resting-state EEG activities in beta and gamma bands and examined their relationships with impulsivity among individuals with Internet addiction and healthy controls. Twenty-one drug-naïve patients with Internet addiction (age: 23.33 ± 3.50 years) and 20 age-, sex-, and IQ-matched healthy controls (age: 22.40 ± 2.33 years) were enrolled in this study. Severity of Internet addiction was identified by the total score on Young's Internet Addiction Test. Impulsivity was measured with the Barratt Impulsiveness Scale-11 and a stop-signal task. Resting-state EEG during eyes closed was recorded, and the absolute/relative power of beta and gamma bands was analyzed. The Internet addiction group showed high impulsivity and impaired inhibitory control. The generalized estimating equation showed that the Internet-addiction group showed lower absolute power on the beta band than did the control group (estimate = -3.370, p < 0.01). On the other hand, the Internet-addiction group showed higher absolute power on the gamma band than did the control group (estimate = 0.434, p < 0.01). These EEG activities were significantly associated with the severity of Internet addiction as well as with the extent of impulsivity. The present study suggests that resting-state fast-wave brain activity is related to the impulsivity characterizing Internet addiction. These differences may be neurobiological markers for the pathophysiology of Internet addiction. Copyright © 2013 Elsevier B.V. All rights reserved.

[Clinical and electrophysiologic studies on epileptic negative myoclonus in atypical benign partial epilepsy of childhood].

PubMed

Yang, Zhi-xian; Liu, Xiao-yan; Qin, Jiong; Zhang, Yue-hua; Bao, Xin-hua; Chang, Xing-zhi; Wu, Ye; Xiong, Hui

2008-12-01

To investigate the clinical, neurophysiologic characteristics and therapeutic considerations of epileptic negative myoclonus (ENM) in atypical benign partial epilepsy of childhood (ABPE). Video-EEG monitoring with outstretched arm tests were carried out in 17 patients, and 9 of them were examined with simultaneous electromyography (EMG). The ENM manifestations, electrophysiologic features and responses to antiepileptic drugs (AED) were analyzed. Seventeen patients were diagnosed as having benign childhood epilepsy with centrotemporal spikes (BECT) during the early course of the disease and were treated with AED. During the course of the disease, hand trembling, objects dropping, head nodding and instability during standing might be clues for ENM occurrence. ENM had been confirmed in our patients by outstretched arm tests during video-EEG recording. The ictal EEG showed that high-amplitude spikes followed by a slow wave over the contralateral motor areas. This was further confirmed by time-locked silent EMG in 9 patients. During ENM occurrence or recurrence, the habitual seizures and interictal discharges were exaggerated. Atypical absence seizures also occurred in 6 patients. The alteration of therapeutic options of AED relating to ENM appearance in some patients included the add-on therapy with carbamazepine (CBZ), oxcarbazepine, phenobarbital, or withdrawal of valproate (VPA). ENM was controlled in most cases by using VPA, clonazepam (CZP) and corticosteroid with different combination. ENM could occur during the course of ABPE. Outstretching arm tests during video-EEG monitoring in combination with EMG was essential to confirm ENM. The ENM occurrence was always associated with the frequency increasing of habitual seizures and the aggravation of interictal discharges. Some AED such as CBZ might induce ENM. VPA, benzodiazepines and corticosteroid with different combination were relatively effective in treatment of ENM.

Respiratory Cycle-Related Electroencephalographic Changes during Sleep in Healthy Children and in Children with Sleep Disordered Breathing

PubMed Central

Immanuel, Sarah A.; Pamula, Yvonne; Kohler, Mark; Martin, James; Kennedy, Declan; Saint, David A.; Baumert, Mathias

2014-01-01

Study Objective: To investigate respiratory cycle-related electroencephalographic changes (RCREC) in healthy children and in children with sleep disordered breathing (SDB) during scored event-free (SEF) breathing periods of sleep. Design: Interventional case-control repeated measurements design. Setting: Paediatric sleep laboratory in a hospital setting. Participants: Forty children with SDB and 40 healthy, age- and sex-matched children. Interventions: Adenotonsillectomy in children with SDB and no intervention in controls. Measurements and Results: Overnight polysomnography; electroencephalography (EEG) power variations within SEF respiratory cycles in the overall and frequency band-specific EEG within stage 2 nonrapid eye movement (NREM) sleep, slow wave sleep (SWS), and rapid eye movement (REM) sleep. Within both groups there was a decrease in EEG power during inspiration compared to expiration across all sleep stages. Compared to controls, RCREC in children with SDB in the overall EEG were significantly higher during REM and frequency band specific RCRECs were higher in the theta band of stage 2 and REM sleep, alpha band of SWS and REM sleep, and sigma band of REM sleep. This between-group difference was not significant postadenotonsillectomy. Conclusion: The presence of nonrandom respiratory cycle-related electroencephalographic changes (RCREC) in both healthy children and in children with sleep disordered breathing (SDB) during NREM and REM sleep has been demonstrated. The RCREC values were higher in children with SDB, predominantly in REM sleep and this difference reduced after adenotonsillectomy. Citation: Immanuel SA, Pamula Y, Kohler M, Martin J, Kennedy D, Saint DA, Baumert M. Respiratory cycle-related electroencephalographic changes during sleep in healthy children and in children with sleep disordered breathing. SLEEP 2014;37(8):1353-1361. PMID:25083016

Carrying the past to the future: Distinct brain networks underlie individual differences in human spatial working memory capacity.

PubMed

Liu, Siwei; Poh, Jia-Hou; Koh, Hui Li; Ng, Kwun Kei; Loke, Yng Miin; Lim, Joseph Kai Wei; Chong, Joanna Su Xian; Zhou, Juan

2018-08-01

Spatial working memory (SWM) relies on the interplay of anatomically separated and interconnected large-scale brain networks. EEG studies often observe load-associated sustained negative activity during SWM retention. Yet, whether and how such sustained negative activity in retention relates to network-specific functional activation/deactivation and relates to individual differences in SWM capacity remain to be elucidated. To cover these gaps, we recorded concurrent EEG-fMRI data in 70 healthy young adults during the Sternberg delayed-match-to-sample SWM task with three memory load levels. To a subset of participants (N = 28) that performed the task properly and had artefact-free fMRI and EEG data, we employed a novel temporo-spatial principal component analysis to derive load-dependent negative slow wave (NSW) from retention-related event-related potentials. The associations between NSW responses with SWM capacity were divergent in the higher (N = 14) and lower (N = 14) SWM capacity groups. Specifically, larger load-related increase in NSW amplitude was associated with greater SWM capacity for the higher capacity group but lower SWM capacity for the lower capacity group. Furthermore, for the higher capacity group, larger NSW amplitude was related to greater activation in bilateral parietal areas of the fronto-parietal network (FPN) and greater deactivation in medial frontal gyrus and posterior mid-cingulate cortex of the default mode network (DMN) during retention. In contrast, the lower capacity group did not show similar pattern. Instead, greater NSW was linked to higher deactivation in right posterior middle temporal gyrus. Our findings shed light on the possible differential EEG-informed neural network mechanism during memory maintenance underlying individual differences in SWM capacity. Copyright © 2018 Elsevier Inc. All rights reserved.

Neural activity based biofeedback therapy for Autism spectrum disorder through wearable wireless textile EEG monitoring system

NASA Astrophysics Data System (ADS)

Sahi, Ahna; Rai, Pratyush; Oh, Sechang; Ramasamy, Mouli; Harbaugh, Robert E.; Varadan, Vijay K.

2014-04-01

Mu waves, also known as mu rhythms, comb or wicket rhythms are synchronized patterns of electrical activity involving large numbers of neurons, in the part of the brain that controls voluntary functions. Controlling, manipulating, or gaining greater awareness of these functions can be done through the process of Biofeedback. Biofeedback is a process that enables an individual to learn how to change voluntary movements for purposes of improving health and performance through the means of instruments such as EEG which rapidly and accurately 'feedback' information to the user. Biofeedback is used for therapeutic purpose for Autism Spectrum Disorder (ASD) by focusing on Mu waves for detecting anomalies in brain wave patterns of mirror neurons. Conventional EEG measurement systems use gel based gold cup electrodes, attached to the scalp with adhesive. It is obtrusive and wires sticking out of the electrodes to signal acquisition system make them impractical for use in sensitive subjects like infants and children with ASD. To remedy this, sensors can be incorporated with skull cap and baseball cap that are commonly used for infants and children. Feasibility of Textile based Sensor system has been investigated here. Textile based multi-electrode EEG, EOG and EMG monitoring system with embedded electronics for data acquisition and wireless transmission has been seamlessly integrated into fabric of these items for continuous detection of Mu waves. Textile electrodes were placed on positions C3, CZ, C4 according to 10-20 international system and their capability to detect Mu waves was tested. The system is ergonomic and can potentially be used for early diagnosis in infants and planning therapy for ASD patients.

Shock wave refraction enhancing conditions on an extended interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Markhotok, A.; Popovic, S.

2013-04-15

We determined the law of shock wave refraction for a class of extended interfaces with continuously variable gradients. When the interface is extended or when the gas parameters vary fast enough, the interface cannot be considered as sharp or smooth and the existing calculation methods cannot be applied. The expressions we derived are general enough to cover all three types of the interface and are valid for any law of continuously varying parameters. We apply the equations to the case of exponentially increasing temperature on the boundary and compare the results for all three types of interfaces. We have demonstratedmore » that the type of interface can increase or inhibit the shock wave refraction. Our findings can be helpful in understanding the results obtained in energy deposition experiments as well as for controlling the shock-plasma interaction in other settings.« less

Survey of shock-wave structures of smooth-particle granular flows.

PubMed

Padgett, D A; Mazzoleni, A P; Faw, S D

2015-12-01

We show the effects of simulated supersonic granular flow made up of smooth particles passing over two prototypical bodies: a wedge and a disk. We describe a way of computationally identifying shock wave locations in granular flows and tabulate the shock wave locations for flow over wedges and disks. We quantify the shock structure in terms of oblique shock angle for wedge impediments and shock standoff distance for disk impediments. We vary granular flow parameters including upstream volume fraction, average upstream velocity, granular temperature, and the collision coefficient of restitution. Both wedges and disks have been used in the aerospace community as prototypical impediments to flowing air in order to investigate the fundamentally different shock structures emanating from sharp and blunt bodies, and we present these results in order to increase the understanding of the fundamental behavior of supersonic granular flow.

Subwavelength wave manipulation in a thin surface-wave bandgap crystal.

PubMed

Gao, Zhen; Wang, Zhuoyuan; Zhang, Baile

2018-01-01

It has been recently reported that the unit cell of wire media metamaterials can be tailored locally to shape the flow of electromagnetic waves at deep-subwavelength scales [Nat. Phys.9, 55 (2013)NPAHAX1745-247310.1038/nphys2480]. However, such bulk structures have a thickness of at least the order of wavelength, thus hindering their applications in the on-chip compact plasmonic integrated circuits. Here, based upon a Sievenpiper "mushroom" array [IEEE Trans. Microwave Theory Tech.47, 2059 (1999)IETMAB0018-948010.1109/22.798001], which is compatible with standard printed circuit board technology, we propose and experimentally demonstrate the subwavelength manipulation of surface waves on a thin surface-wave bandgap crystal with a thickness much smaller than the wavelength (1/30th of the operating wavelength). Functional devices including a T-shaped splitter and sharp bend are constructed with good performance.

Effects of evening bright light exposure on melatonin, body temperature and sleep.

PubMed

Bunnell; Treiber; Phillips; Berger

1992-03-01

Five male subjects were exposed to a single 2-h period of bright (2500 lux) or dim (<100 lux) light prior to sleep on two consecutive nights. The two conditions were repeated the following week in opposite order. Bright light significantly suppressed salivary melatonin and raised rectal temperature 0.3 degrees C (which remained elevated during the first 1.5 h of sleep), without affecting tympanic temperature. Bright light also increased REM latency, NREM period length, EEG spectral power in low frequency, 0.75-8 Hz and sigma, 12-14 Hz (sleep spindle) bandwidths during the first hour of sleep, and power of all frequency bands (0.5-32 Hz) within the first NREMP. Potentiation of EEG slow wave activity (0.5-4.0 Hz) by bright light persisted through the end of the second NREMP. The enhanced low-frequency power and delayed REM sleep after bright light exposure could represent a circadian phase-shift and/or the effect of an elevated rectal temperature, possibly mediated by the suppression of melatonin.

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Instability and Death of Spiral Wave in a Two-Dimensional Array of Hindmarsh-Rose Neurons

NASA Astrophysics Data System (ADS)

Wang, Chun-Ni; Ma, Jun; Tang, Jun; Li, Yan-Long

2010-02-01

Spiral wave could be observed in the excitable media, the neurons are often excitable within appropriate parameters. The appearance and formation of spiral wave in the cardiac tissue is linked to monomorphic ventricular tachycardia that can denervate into polymorphic tachycardia and ventricular fibrillation. The neuronal system often consists of a large number of neurons with complex connections. In this paper, we theoretically study the transition from spiral wave to spiral turbulence and homogeneous state (death of spiral wave) in two-dimensional array of the Hindmarsh-Rose neuron with completely nearest-neighbor connections. In our numerical studies, a stable rotating spiral wave is developed and selected as the initial state, then the bifurcation parameters are changed to different values to observe the transition from spiral wave to homogeneous state, breakup of spiral wave and weak change of spiral wave, respectively. A statistical factor of synchronization is defined with the mean field theory to analyze the transition from spiral wave to other spatial states, and the snapshots of the membrane potentials of all neurons and time series of mean membrane potentials of all neurons are also plotted to discuss the change of spiral wave. It is found that the sharp changing points in the curve for factor of synchronization vs. bifurcation parameter indicate sudden transition from spiral wave to other states. And the results are independent of the number of neurons we used.

Lennox-Gastaut syndrome of unknown cause: phenotypic characteristics of patients in the Epilepsy Phenome/Genome Project.

PubMed

Widdess-Walsh, Peter; Dlugos, Dennis; Fahlstrom, Robyn; Joshi, Sucheta; Shellhaas, Renée; Boro, Alex; Sullivan, Joseph; Geller, Eric

2013-11-01

Lennox-Gastaut syndrome (LGS) is a devastating childhood-onset epilepsy syndrome. The cause is unknown in 25% of cases. Little has been described about the specific clinical or electroencephalography (EEG) features of LGS of unknown or genetic cause (LGS(u)). The Epilepsy Phenome/Genome Project (EPGP) aims to characterize LGS(u) by phenotypic analysis of patients with LGS(u) and their parents. One hundred thirty-five patients with LGS with no known etiology and their parents were enrolled from 19 EPGP centers in the United States and Australia. Clinical data from medical records, standardized questionnaires, imaging, and EEG were collected with use of online informatics systems developed for EPGP. LGS(u) in the EPGP cohort had a broad range of onset of epilepsy from 1 to 13 years, was male predominant (p < 0.0002), and was associated with normal development prior to seizure onset in 59.2% of patients. Despite the diagnosis, almost half of the adult patients with LGS(u) completed secondary school. Parents were cognitively normal. All subjects had EEG recordings with generalized epileptiform abnormalities with a spike wave frequency range of 1-5 Hz (median 2 Hz), whereas 8.1% of subjects had EEG studies with a normal posterior dominant rhythm. Almost 12% of patients evolved from West syndrome. LGS(u) has distinctive characteristics including a broad age range of onset, male predominance, and often normal development prior to the onset of seizures. Cognitive achievements such as completion of secondary school were possible in half of adult patients. Our phenotypic description of LGS(u) coupled with future genetic studies will advance our understanding of this epilepsy syndrome. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.

EEG Changes Accompanying Successive Cycles of Sleep Restriction With and Without Naps in Adolescents.

PubMed

Ong, Ju Lynn; Lo, June C; Gooley, Joshua J; Chee, Michael W L

2017-04-01

To investigate the temporal evolution of sleep EEG changes in adolescents across two cycles of sleep restriction and recovery simulating an intense school week and to examine the effect of an afternoon nap on nocturnal sleep. A parallel-group design, quasi-laboratory study was conducted in a student hostel. Fifty-seven adolescents (31 males, age = 15-19 years) were randomly assigned to nap or no nap groups. Participants underwent a 15-day protocol comprising two sleep restriction (5-hour time-in-bed [TIB]) and recovery (9-hour TIB) cycles. The nap group was also provided with a 1-hour nap opportunity at 14:00 following each sleep restriction night. Polysomnography recordings were obtained on nine nights and five nap episodes. Naps reduced homeostatic sleep pressure on sleep restriction nights as evidenced by longer N2 latency and reduced total sleep time (TST), sleep efficiency (SE), and slow wave energy. Sleep debt accumulated in both groups, evidenced by increased TST, greater SE, and reduced wake after sleep onset on recovery compared to baseline nights. Changes were greater in the no nap group. Recovery sleep after the first cycle of sleep restriction did not restore sleep architecture to baseline in either group. SE, rapid eye movement (REM), and non-REM sleep increased, and N2 latency was reduced in the second sleep restriction period. Changes in sleep EEG induced by sleep restriction to 5-hour TIB for five nights were not eliminated after two nights of 9-hour recovery sleep. An afternoon nap helped but residual effects on the sleep EEG suggest that there is no substitute for adequate nocturnal sleep. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

Temporal Organization of the Sleep-Wake Cycle under Food Entrainment in the Rat

PubMed Central

Castro-Faúndez, Javiera; Díaz, Javier; Ocampo-Garcés, Adrián

2016-01-01

Study Objectives: To analyze the temporal organization of the sleep-wake cycle under food entrainment in the rat. Methods: Eighteen male Sprague-Dawley rats were chronically implanted for polysomnographic recording. During the baseline (BL) protocol, rats were recorded under a 12:12 light-dark (LD) schedule in individual isolation chambers with food and water ad libitum. Food entrainment was performed by means of a 4-h food restriction (FR) protocol starting at photic zeitgeber time 5. Eight animals underwent a 3-h phase advance of the FR protocol (A-FR). We compared the mean curves and acrophases of wakefulness, NREM sleep, and REM sleep under photic and food entrainment and after a phase advance in scheduled food delivery. We further evaluated the dynamics of REM sleep homeostasis and the NREM sleep EEG delta wave profile. Results: A prominent food-anticipatory arousal interval was observed after nine or more days of FR, characterized by increased wakefulness and suppression of REM sleep propensity and dampening of NREM sleep EEG delta activity. REM sleep exhibited a robust nocturnal phase preference under FR that was not explained by a nocturnal REM sleep rebound. The mean curve of sleep-wake states and NREM sleep EEG delta activity remained phase-locked to the timing of meals during the A-FR protocol. Conclusions: Our results support the hypothesis that under food entrainment, the sleep-wake cycle is coupled to a food-entrainable oscillator (FEO). Our findings suggest an unexpected interaction between FEO output and NREM sleep EEG delta activity generators. Citation: Castro-Faúndez J, Díaz J, Ocampo-Garcés A. Temporal organization of the sleep-wake cycle under food entrainment in the rat. SLEEP 2016;39(7):1451–1465. PMID:27091526

Interictal epileptic discharge correlates with global and frontal cognitive dysfunction in temporal lobe epilepsy.

PubMed

Dinkelacker, Vera; Xin, Xu; Baulac, Michel; Samson, Séverine; Dupont, Sophie

2016-09-01

Temporal lobe epilepsy (TLE) with hippocampal sclerosis has widespread effects on structural and functional connectivity and often entails cognitive dysfunction. EEG is mandatory to disentangle interactions in epileptic and physiological networks which underlie these cognitive comorbidities. Here, we examined how interictal epileptic discharges (IEDs) affect cognitive performance. Thirty-four patients (right TLE=17, left TLE=17) were examined with 24-hour video-EEG and a battery of neuropsychological tests to measure intelligence quotient and separate frontal and temporal lobe functions. Hippocampal segmentation of high-resolution T1-weighted imaging was performed with FreeSurfer. Partial correlations were used to compare the number and distribution of clinical interictal spikes and sharp waves with data from imagery and psychological tests. The number of IEDs was negatively correlated with executive functions, including verbal fluency and intelligence quotient (IQ). Interictal epileptic discharge affected cognitive function in patients with left and right TLE differentially, with verbal fluency strongly related to temporofrontal spiking. In contrast, IEDs had no clear effects on memory functions after corrections with partial correlations for age, age at disease onset, disease duration, and hippocampal volume. In patients with TLE of long duration, IED occurrence was strongly related to cognitive deficits, most pronounced for frontal lobe function. These data suggest that IEDs reflect dysfunctional brain circuitry and may serve as an independent biomarker for cognitive comorbidity. Copyright © 2016. Published by Elsevier Inc.

RESPIRATORY MODULATION OF LINGUAL MUSCLE ACTIVITY ACROSS SLEEP-WAKE STATES IN RATS

PubMed Central

Stettner, Georg M.; Rukhadze, Irma; Mann, Graziella L.; Lei, Yanlin; Kubin, Leszek

2013-01-01

In obstructive sleep apnea (OSA) patients, inspiratory activation (IA) of lingual muscles protects the upper airway from collapse. We aimed to determine when rats’ lingual muscles exhibit IA. In 5 Sprague-Dawley and 3 Wistar rats, we monitored cortical EEG and lingual, diaphragmatic and nuchal electromyograms (EMGs), and identified segments of records when lingual EMG exhibited IA. Individual segments lasted 2.4–269 s (median: 14.5 s), most (89%) occurred during slow-wave sleep (SWS), and they collectively occupied 0.3–6.1% of the total recording time. IA usually started to increase with a delay after SWS onset and ended with an arousal, or declined prior to rapid eye movement sleep. IA of lingual EMG was not accompanied by increased diaphragmatic activity or respiratory rate changes, but occurred when cortical EEG power was particularly low in a low beta-1 frequency range (12.5–16.4 Hz). A deep SWS-related activation of upper airway muscles may be an endogenous phenomenon designed to protect the upper airway against collapse. PMID:23732510

Concentrated energy addition for active drag reduction in hypersonic flow regime

NASA Astrophysics Data System (ADS)

Ashwin Ganesh, M.; John, Bibin

2018-01-01

Numerical optimization of hypersonic drag reduction technique based on concentrated energy addition is presented in this study. A reduction in wave drag is realized through concentrated energy addition in the hypersonic flowfield upstream of the blunt body. For the exhaustive optimization presented in this study, an in-house high precision inviscid flow solver has been developed. Studies focused on the identification of "optimum energy addition location" have revealed the existence of multiple minimum drag points. The wave drag coefficient is observed to drop from 0.85 to 0.45 when 50 Watts of energy is added to an energy bubble of 1 mm radius located at 74.7 mm upstream of the stagnation point. A direct proportionality has been identified between energy bubble size and wave drag coefficient. Dependence of drag coefficient on the upstream added energy magnitude is also revealed. Of the observed multiple minimum drag points, the energy deposition point (EDP) that offers minimum wave drag just after a sharp drop in drag is proposed as the most optimum energy addition location.

[Neurofeedback therapy in the treatment of tinnitus].

PubMed

Zhao, Z Q; Lei, G X; Li, Y L; Zhang, D; Shen, W D; Yang, S M; Qiao, Y H

2018-02-01

Neurofeedback therapy is a fast-growing field of tinnitus treatment, which is a new type of biofeedback therapy. In the past, the "muscle tone" and "blood flow" were used as feedback signals in biofeedback therapy to treat tinnitus, however there was no long-term follow-up report. Instead, neurofeedback therapy utilizes EEG (electroencephalogram) as the feedback signal, which is also called EEG biofeedback therapy. At present, most treatments of tinnitus only record subjective measures of patients as evaluation indicators, whereas neurofeedback therapy is more convincing for using comprehensive evaluation including changes of brain wave as objective indicators and subjective measures of patients. A significant number of tinnitus patients have varying degree of hearing loss. As neurofeedback therapy takes advantage of EEG as feedback signal that is delivered to the patients through visual information, it has unique advantages of being not affected by the degree of hearing loss compared to the sound masking or other sound treatment. Long-term follow-up results showed that the efficacy of neurofeedback therapy was stable after half a year of short-term treatment. This paper summarizes the progress of the various types of biofeedback therapy in the treatment of tinnitus, and focuses on the neurofeedback therapy for the mechanism, indication, process, efficacy evaluation, defect and prospect of neurofeedback therapy in tinnitus treatment in order to help promote the development of domestic clinical neurofeedback therapy in tinnitus.

Sustained attention performance during sleep deprivation associates with instability in behavior and physiologic measures at baseline.

PubMed

Chua, Eric Chern-Pin; Yeo, Sing-Chen; Lee, Ivan Tian-Guang; Tan, Luuan-Chin; Lau, Pauline; Cai, Shiwei; Zhang, Xiaodong; Puvanendran, Kathiravelu; Gooley, Joshua J

2014-01-01

To identify baseline behavioral and physiologic markers that associate with individual differences in sustained attention during sleep deprivation. In a retrospective study, ocular, electrocardiogram, and electroencephalogram (EEG) measures were compared in subjects who were characterized as resilient (n = 15) or vulnerable (n = 15) to the effects of total sleep deprivation on sustained attention. Chronobiology and Sleep Laboratory, Duke-NUS Graduate Medical School Singapore. Healthy volunteers aged 22-32 years from the general population. Subjects were kept awake for at least 26 hours under constant environmental conditions. Every 2 hours, sustained attention was assessed using a 10-minute psychomotor vigilance task (PVT). During baseline sleep and recovery sleep, EEG slow wave activity was similar in resilient versus vulnerable subjects, suggesting that individual differences in vulnerability to sleep loss were not related to differences in homeostatic sleep regulation. Rather, irrespective of time elapsed since wake, subjects who were vulnerable to sleep deprivation exhibited slower and more variable PVT response times, lower and more variable heart rate, and higher and more variable EEG spectral power in the theta frequency band (6.0-7.5 Hz). Performance decrements in sustained attention during sleep deprivation associate with instability in behavioral and physiologic measures at baseline. Small individual differences in sustained attention that are present at baseline are amplified during prolonged wakefulness, thus contributing to large between-subjects differences in performance and sleepiness.

Transformation of Waves Across the Surf Zone.

DTIC Science & Technology

1981-03-01

Kuo is more realis- tic but still results in a sharp cut-off of the distribution at the breaking heights. 5. Goda Distribution Goda (1975) derived a...J.I., "Probabilities of Breaking Wave Characteris- tics ," Proc. 12th Coastal Engineering Conf., pp. 399- 412, 1970. Chakrabarty, S.K. and R.P. Cooley...Spring, MD 20910 21. Director 2 Instituto Oceanografico de la Armada Guayaquil, Ecuador 22. Director de Educacion de la Armada Comandancia General de

Cosmic clustering

DOE PAGES

Anninos, Dionysios; Denef, Frederik

2016-06-30

We show that the late time Hartle-Hawking wave function for a free massless scalar in a fixed de Sitter background encodes a sharp ultrametric structure for the standard Euclidean distance on the space of field configurations. This implies a hierarchical, tree-like organization of the state space, reflecting its genesis as a branched diffusion process. In conclusion, an equivalent mathematical structure organizes the state space of the Sherrington-Kirkpatrick model of a spin glass.

Ultrasound shock wave generator with one-bit time reversal in a dispersive medium, application to lithotripsy

NASA Astrophysics Data System (ADS)

Montaldo, Gabriel; Roux, Philippe; Derode, Arnaud; Negreira, Carlos; Fink, Mathias

2002-02-01

The building of high-power ultrasonic sources from piezoelectric ceramics is limited by the maximum voltage that the ceramics can endure. We have conceived a device that uses a small number of piezoelectric transducers fastened to a cylindrical metallic waveguide. A one-bit time- reversal operation transforms the long-lasting low-level dispersed wave forms into a sharp pulse, thus taking advantage of dispersion to generate high-power ultrasound. The pressure amplitude that is generated at the focus is found to be 15 times greater than that achieved with comparable standard techniques. Applications to lithotripsy are discussed and the destructive efficiency of the system is demonstrated on pieces of chalk.

Study of Proximity Effect at D-Wave Superconductors in Quasiclassical Methods

NASA Astrophysics Data System (ADS)

Tanuma, Y.; Tanaka, Y.; Kashiwaya, S.

2005-08-01

Tunneling spectra via Andreev bound states between a normal metal (N) / dx2-y2-wave superconductor (S) (in the presence of a subdominant s-wave pair potential) junction are investigated. In the present work, in order to study the role of proximity effect, we employ quasiclassical Green's function methods. This merit is that we can determine the spatial variation of the pair potentials self-consistently, where the leaking of pair potentials into the N side is involved. In the N/S junction with orientational angle θ = π/4, we can regard as the isolated d-wave superconductor, where attractive interaction in the N side is negligible. On the other hand, in the case of a high transparent contact to the d-wave superconductor (θ = 0), the pair potential penetrates into the inside of the N due to the proximity effect, where the is-wave is not indued at all. Then, the tunneling spectra has a very sharp zero-energy peak (ZEP). This ZEP originates from the fact that quasiparticles feel different sign of the pair potentials between normal metals and d-wave superconductors through Andreev reflections. We show that the spatial dependence of pair potentials is significantly sensitive to the transparency of the junction.

EEG Changes Accompanying Successive Cycles of Sleep Restriction With and Without Naps in Adolescents

PubMed Central

Ong, Ju Lynn; Lo, June C.; Gooley, Joshua J.

2017-01-01

Abstract Study objectives: To investigate the temporal evolution of sleep EEG changes in adolescents across two cycles of sleep restriction and recovery simulating an intense school week and to examine the effect of an afternoon nap on nocturnal sleep. Methods: A parallel-group design, quasi-laboratory study was conducted in a student hostel. Fifty-seven adolescents (31 males, age = 15–19 years) were randomly assigned to nap or no nap groups. Participants underwent a 15-day protocol comprising two sleep restriction (5-hour time-in-bed [TIB]) and recovery (9-hour TIB) cycles. The nap group was also provided with a 1-hour nap opportunity at 14:00 following each sleep restriction night. Polysomnography recordings were obtained on nine nights and five nap episodes. Results: Naps reduced homeostatic sleep pressure on sleep restriction nights as evidenced by longer N2 latency and reduced total sleep time (TST), sleep efficiency (SE), and slow wave energy. Sleep debt accumulated in both groups, evidenced by increased TST, greater SE, and reduced wake after sleep onset on recovery compared to baseline nights. Changes were greater in the no nap group. Recovery sleep after the first cycle of sleep restriction did not restore sleep architecture to baseline in either group. SE, rapid eye movement (REM), and non-REM sleep increased, and N2 latency was reduced in the second sleep restriction period. Conclusions: Changes in sleep EEG induced by sleep restriction to 5-hour TIB for five nights were not eliminated after two nights of 9-hour recovery sleep. An afternoon nap helped but residual effects on the sleep EEG suggest that there is no substitute for adequate nocturnal sleep. PMID:28329386

Diurnal changes in glutamate + glutamine levels of healthy young adults assessed by proton magnetic resonance spectroscopy.

PubMed

Volk, Carina; Jaramillo, Valeria; Merki, Renato; O'Gorman Tuura, Ruth; Huber, Reto

2018-06-08

The glutamatergic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor is involved in synaptic plasticity processes, and animal studies have demonstrated altered expression across the sleep wake cycle. Accordingly, glutamate levels are reduced during non-rapid eye movement (NREM) sleep and the rate of this decrease is positively correlated with sleep EEG slow wave activity (SWA). Here, we combined proton magnetic resonance spectroscopy ( 1 H-MRS) and high-density sleep EEG to assess if 1 H-MRS is sensitive to diurnal changes of glutamate + glutamine (GLX) in healthy young adults and if potential overnight changes of GLX are correlated to SWA. 1 H-MRS was measured in the parietal lobe in the evening and in the subsequent morning. High-density sleep EEG was recorded overnight between the evening and morning scans. Our results revealed a significant overnight reduction in GLX, but no significant changes in other metabolites. The decrease in GLX positively correlated with the decrease of SWA. Our study demonstrates that quantification of diurnal changes in GLX is possible by means of 1 H-MRS and indicates that overnight changes in GLX are related to SWA, a marker that is closely linked to the restorative function of sleep. This relationship might be of particular interest in clinical populations in which sleep is disturbed. © 2018 Wiley Periodicals, Inc.

Detection of nonlinear interactions of EEG alpha waves in the brain by a new coherence measure and its application to epilepsy and anti-epileptic drug therapy.

PubMed

Sherman, David; Zhang, Ning; Garg, Shikha; Thakor, Nitish V; Mirski, Marek A; White, Mirinda Anderson; Hinich, Melvin J

2011-04-01

EEG and field potential rhythms established in the cortex and thalamus may accommodate the propagation of seizures. This article describes the interaction between thalamus and cortex during pentylenetetrazol (PTZ) seizures in rats with and without prior treatment with ethosuximide (ESM), a well-known antiepileptic drug (AED) that raises the threshold for seizures, was given before PTZ. The AED was given before PTZ convulsant administration. We track this thalamo-cortical association with a novel measure we have called the cross-bicoherence gain, or BISCOH. This quantity allows us to measure the spectral coherence in a purely higher order spectralmethodology. BISCOH is able to track the formation of nonlinearities at specific frequencies in the recorded EEG. BISCOH showed a strong increase in low alpha wave harmonic generationat 10 and 12.5 Hz after ESM treatment (p < 0.02 and p < 0.007, respectively). Conventional coherence failed to show distinctive and significant changes in thalamo-cortical coupling after ESM treatment at those frequencies and instead showed changes at 5 Hz. This rise in cortical rhythms is evidence of harmonic generation or new frequency formation in the thalamo-cortical system withAED therapy. BISCOH could become a powerful tool in unraveling changes in coherence due to neuroelectric modulation resulting from drug treatment or electrical stimulation.

The transcription factor DBP affects circadian sleep consolidation and rhythmic EEG activity.

PubMed

Franken, P; Lopez-Molina, L; Marcacci, L; Schibler, U; Tafti, M

2000-01-15

Albumin D-binding protein (DBP) is a PAR leucine zipper transcription factor that is expressed according to a robust circadian rhythm in the suprachiasmatic nuclei, harboring the circadian master clock, and in most peripheral tissues. Mice lacking DBP display a shorter circadian period in locomotor activity and are less active. Thus, although DBP is not essential for circadian rhythm generation, it does modulate important clock outputs. We studied the role of DBP in the circadian and homeostatic aspects of sleep regulation by comparing DBP deficient mice (dbp-/-) with their isogenic controls (dbp+/+) under light-dark (LD) and constant-dark (DD) baseline conditions, as well as after sleep loss. Whereas total sleep duration was similar in both genotypes, the amplitude of the circadian modulation of sleep time, as well as the consolidation of sleep episodes, was reduced in dbp-/- under both LD and DD conditions. Quantitative EEG analysis demonstrated a marked reduction in the amplitude of the sleep-wake-dependent changes in slow-wave sleep delta power and an increase in hippocampal theta peak frequency in dbp-/- mice. The sleep deprivation-induced compensatory rebound of EEG delta power was similar in both genotypes. In contrast, the rebound in paradoxical sleep was significant in dbp+/+ mice only. It is concluded that the transcriptional regulatory protein DBP modulates circadian and homeostatic aspects of sleep regulation.

Effects of neurofeedback therapy in healthy young subjects.

PubMed

Altan, Sümeyra; Berberoglu, Bercim; Canan, Sinan; Dane, Şenol

2016-12-01

Neurofeedback refers to a form of operant conditioning of electrical brain activity, in which desirable brain activity is rewarded and undesirable brain activity is inhibited. The research team aimed to examine the efficacy of neurofeedback therapy on electroencephalogram (EEG) for heart rate, electrocardiogram (ECG) and galvanic skin resistance (GSR) parameters in a healthy young male population. Forty healthy young male subjects aged between 18 to 30 years participated in this study. Neurofeedback application of one session was made with bipolar electrodes placed on T3 and T4 (temporal 3 and 4) regions and with reference electrode placed on PF1 (prefrontal 1). Electroencephalogram (EEG), electrocardiogram (ECG) and galvanic skin resistance (GSR) were assessed during Othmer neurofeedback application of one session to regulate slow wave activity for forty minutes thorough the session. Data assessed before neurofeedback application for 5 minutes and during neurofeedback application of 30 minutes and after neurofeedback application for 5 minutes throughout the session of 40 minutes. Means for each 5 minutes, that is to say, a total 8 data points for each subjects over 40 minutes, were assessed. Galvanic skin resistance increased and heart rate decreased after neurofeedback therapy. Beta activity in EEG increased and alfa activity decreased after neurofeedback therapy. These results suggest that neurofeedback can be used to restore sympathovagal imbalances. Also, it may be accepted as a preventive therapy for psychological and neurological problems.

BDNF mRNA abundance regulated by antidromic action potentials and AP-LTD in hippocampus.

PubMed

Bukalo, Olena; Lee, Philip R; Fields, R Douglas

2016-12-02

Action-potential-induced LTD (AP-LTD) is a form of synaptic plasticity that reduces synaptic strength in CA1 hippocampal neurons firing antidromically during sharp-wave ripples. This firing occurs during slow-wave sleep and quiet moments of wakefulness, which are periods of offline replay of neural sequences learned during encoding sensory information. Here we report that rapid and persistent down-regulation of different mRNA transcripts of the BDNF gene accompanies AP-LTD, and that AP-LTD is abolished in mice with the BDNF gene knocked out in CA1 hippocampal neurons. These findings increase understanding of the mechanism of AP-LTD and the cellular mechanisms of memory consolidation. Published by Elsevier Ireland Ltd.

Repeated sharp flux dropouts observed at 6.6 earth radii during a geomagnetic storm

NASA Technical Reports Server (NTRS)

Su, S.-Y.; Fritz, T. A.; Konradi, A.

1976-01-01

A number of repeated rapid flux dropouts have been observed at 6.6 earth radii by the low-energy proton detectors on board the ATS 6 satellite during the July 4-6, 1974, geomagnetic storm period. These rapid flux changes are caused by the fact that the outer boundary of the trapped radiation region moves back and forth past the satellite. Although a tilting field line configuration can cause the boundary to pass the satellite, as has frequently been reported in the literature, the boundary is shown to be distorted by a large surface wave traveling eastward around the earth. The maximum velocity of the wave was observed to be about 40 km/s.

Circadian Gene Variants Influence Sleep and the Sleep Electroencephalogram in Humans

PubMed Central

Chang, Anne-Marie; Bjonnes, Andrew; Aeschbach, Daniel; Buxton, Orfeu M.; Gooley, Joshua J.; Anderson, Clare; Van Reen, Eliza; Cain, Sean W.; Czeisler, Charles A.; Duffy, Jeanne F.; Lockley, Steven W.; Shea, Steven; Scheer, Frank A.J.L.; Saxena, Richa

2017-01-01

The sleep electroencephalogram is highly heritable in humans and yet little is known about the genetic basis of inter-individual differences in sleep architecture. The aim of this study was to identify associations between candidate circadian gene variants and the polysomnogram, recorded under highly controlled laboratory conditions during a baseline, overnight, 8-h sleep opportunity. A candidate gene approach was employed to analyze single nucleotide polymorphisms from five circadian-related genes in a two-phase analysis of 84 healthy young adults (28 F; 23.21 ± 2.97 years) of European ancestry. A common variant in Period2 (PER2) was associated with 20 minutes less slow wave sleep (SWS) in carriers of the minor allele than in non-carriers, representing a 22% difference in SWS duration. Moreover, spectral analysis in a subset of samples (n=37), showed the same PER2 polymorphism was associated with reduced EEG power density in the low delta range (0.25–1.0 Hz) during non-REM sleep and lower slow-wave activity (0.75–4.5 Hz) in the early part of the sleep episode. These results indicate the involvement of PER2 in the homeostatic process of sleep. Additionally, a rare variant in Melatonin Receptor 1B was associated with longer REM sleep latency, with minor allele carriers exhibiting an average of 65 minutes (87%) longer latency from sleep onset to REM sleep, compared to non-carriers. These findings suggest that circadian-related genes may modulate sleep architecture and the sleep EEG, including specific parameters previously implicated in the homeostatic regulation of sleep. PMID:27089043

Synchrony of two uncoupled neurons under half wave sine current stimulation

NASA Astrophysics Data System (ADS)

Peng, Yueping; Wang, Jue; Jian, Zhong

2009-04-01

Two uncoupled Hindmarsh-Rose neurons under different initial discharge patterns are stimulated by the half wave sine current; and the synchronization mechanism of the two neurons is discussed by analyzing their membrane potentials and their interspike interval (ISI) distribution. Under the half wave sine current stimulation, the two uncoupled neurons under different initial conditions, whose parameter r (the parameter r is related to the membrane penetration of calcium ion, and reflects the changing speed of the slow adaptation current) is different or the same, can realize discharge synchronization (phase synchronization) or the full synchronization (state synchronization). The synchronization characteristics are mainly related to the frequency and the amplitude of the half wave sine current, and are little related to the parameter r and the initial state of the two neurons. This investigation shows the mechanism of the current's amplitude and its frequency affecting the synchronization process of neurons, and the neurons' discharge patterns and synchronization process can be adjusted and controlled by the current's amplitude and its frequency. This result is of far reaching importance to study synchronization and encode of many neurons or neural network, and provides the theoretic basis for studying the mechanism of some nervous diseases such as epilepsy and Alzheimer's disease by the slow wave of EEG.

Adiabatic description of superfocusing of femtosecond plasmon polaritons

NASA Astrophysics Data System (ADS)

Golovinski, P. A.; Manuylovich, E. S.; Astapenko, V. A.

2018-05-01

A surface plasmon polariton is a collective oscillation of free electrons at a metal-dielectric interface. As wave phenomena, surface plasmon polaritons can be focused with the use of an appropriate excitation geometry of metal structures. In the adiabatic approximation, we demonstrate a possibility to control nanoscale short pulse superfocusing based on generation of a radially polarized surface plasmon polariton mode of a conical metal needle in view of wave reflection. The results of numerical simulations of femtosecond pulse propagation along a nanoneedle are discussed. The space-time evolution of a pulse for the near field strongly depends on a linear chirp of an initial laser pulse, which can partially compensate wave dispersion. The field distribution is calculated for different metals, chirp parameters, cone opening angles and propagation distances. The electric field near a sharp tip is described as a field of a fictitious time-dependent electric dipole located at the tip apex.

Effect of cooler electrons on a compressive ion acoustic solitary wave in a warm ion plasma — Forbidden regions, double layers, and supersolitons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, S. S., E-mail: sukti@iigs.iigm.res.in; Sekar Iyengar, A. N.

It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leadsmore » to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons.« less

Simultaneous Changes in Sleep, qEEG, Physiology, Behaviour and Neurochemistry in Rats Exposed to Repeated Social Defeat Stress.

PubMed

Ahnaou, A; Drinkenburg, W H I M

2016-01-01

Depression is a heterogeneous disorder characterized by alterations at psychological, behavioural, physiological, neurophysiological, and neurochemical levels. Social stress is a prevalent stress in man, and the repeated social defeat stress model in rats has been proposed as being the rodent equivalent to loss of control, which in subordinate animals produces alterations that resemble several of the cardinal symptoms found in depressed patients. Here, rats followed a resident-intruder protocol for 4 consecutive days during which behavioural, physiological, and electroencephalographic (EEG) parameters were simultaneously monitored in subordinate rats. On day 5, prefrontal dopamine (DA) and hippocampal serotonin (5-HT) as well as corticosterone were measured in submissive rats that had visual, acoustic, and olfactory (but no physical) contact with a dominant, resident conspecific rat. Socially defeated rats demonstrated increases in ultrasonic vocalizations (20-25 KHz), freezing, submissive defensive behaviour, inactivity, and haemodynamic response, while decreases were found in repetitive grooming behaviour and body weight. Additionally, alterations in the sleep-wake architecture were associated with reduced active waking, enhanced light sleep, and increased frequency of transitions from light sleep to quiet wakefulness, indicating sleep instability. Moreover, the attenuation of EEG power over the frequency range of 4.2-30 Hz, associated with a sharp transient increase in delta oscillations, appeared to reflect increased brain activity and metabolism in subordinate animals. These EEG changes were synchronous with a marked increase in body temperature and a decrease in locomotor activity. Furthermore, psychosocial stress consistently increased 5-HT, DA, and corticosterone levels. The increased levels of cortical DA and hippocampal 5-HT during social threat may reflect a coping mechanism to promote alertness and psychological adaptation to provocative and threatening stimuli. These neurophysiological changes are hypothesized to be the consequence of dynamics in monoamine systems, which could be useful markers for disease progression in the aetiology of depression. © 2016 S. Karger AG, Basel.

Sharp-Wave Ripples in Primates Are Enhanced near Remembered Visual Objects.

PubMed

Leonard, Timothy K; Hoffman, Kari L

2017-01-23

The hippocampus plays an important role in memory for events that are distinct in space and time. One of the strongest, most synchronous neural signals produced by the hippocampus is the sharp-wave ripple (SWR), observed in a variety of mammalian species during offline behaviors, such as slow-wave sleep [1-3] and quiescent waking and pauses in exploration [4-8], leading to long-standing and widespread theories of its contribution to plasticity and memory during these inactive or immobile states [9-14]. Indeed, during sleep and waking inactivity, hippocampal SWRs in rodents appear to support spatial long-term and working memory [4, 15-23], but so far, they have not been linked to memory in primates. More recently, SWRs have been observed during active, visual scene exploration in macaques [24], opening up the possibility that these active-state ripples in the primate hippocampus are linked to memory for objects embedded in scenes. By measuring hippocampal SWRs in macaques during search for scene-contextualized objects, we found that SWR rate increased with repeated presentations. Furthermore, gaze during SWRs was more likely to be near the target object on repeated than on novel presentations, even after accounting for overall differences in gaze location with scene repetition. This proximity bias with repetition occurred near the time of target object detection for remembered targets. The increase in ripple likelihood near remembered visual objects suggests a link between ripples and memory in primates; specifically, SWRs may reflect part of a mechanism supporting the guidance of search based on past experience. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thermal Transport in Nd-doped CeCoIn5

NASA Astrophysics Data System (ADS)

Kim, Duk Y.; Lin, Shi-Zeng; Weickert, Franziska; Rosa, P. F. S.; Bauer, Eric D.; Ronning, Filip; Thompson, J. D.; Movshovich, Roman

Heavy-fermion superconductor CeCoIn5 shows spin-density-wave (SDW) magnetic order in its superconducting state when a high magnetic field is applied. In this Q-phase, the antiferromagnetic order has a single ordering wave vector, and switches its orientation very sharply as magnetic field is rotated within the ab -plane around the [100] (anti-nodal) direction. This hypersensitivity induces a sharp jump of the thermal conductivity. Recently, the SDW with the same ordering wave vector was observed in Nd-doped CeCoIn5 in zero magnetic field. We have measured the thermal conductivity of 5% Nd-doped CeCoIn5 in the magnetic field rotating within the ab -plane. The anisotropy is significantly smaller in the doped material, and the switching transition is much broader. The superconducting transition near Hc 2 is first order, as for the pure CeCoIn5, which indicates the Pauli limited superconductivity. We gratefully acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.

Investigations on flexural wave propagation and attenuation in a modified one-dimensional acoustic black hole using a laser excitation technique

NASA Astrophysics Data System (ADS)

Ji, Hongli; Luo, Jing; Qiu, Jinhao; Cheng, Li

2018-05-01

Acoustic Black Holes (ABHs), as a new type of passive structure for vibration damping enhancement and noise attenuation, have been drawing increasing attentions of many researchers. Due to the difficulty in manufacturing the sharp edges required by the ABH structures, it is important to understand the wave propagation and attenuation process in the presence of damping layers in non-ideal ABHs with a truncated edge. In this paper, an analytical expression of the wave reflection coefficient in a modified one-dimensional ABH is derived and a time-domain experimental method based on a laser excitation technique is used to visualize the wave propagation. In the experimental studies, the flexural waves in the ABH were excited by a scanning pulse laser and measured by a Laser Doppler Vibrometer (LDV). The incident wave and reflected wave were separated from the measured original wave field and the decrease of the wave velocity in the ABH was exhibited. The reflection coefficient was calculated from the ratio of the amplitude of the reflected wave to that of the incident wave for different ABH parameters and different thicknesses of the damping layer. The measured reflection coefficients were used to identify the unknown coefficients in the theoretical formula. The results confirm that there exists an optimal thickness for the damping layer, which leads to the minimum wave reflection. Based on the laser-induced visualization technique and various signal processing and feature extraction methods, the entire process of the wave propagation in a non-ideal one-dimensional ABH structure can be visualized and scrutinized.

Non-invasive monitoring of spreading depression.

PubMed

Bastany, Zoya J R; Askari, Shahbaz; Dumont, Guy A; Speckmann, Erwin-Josef; Gorji, Ali

2016-10-01

Spreading depression (SD), a slow propagating depolarization wave, plays an important role in pathophysiology of different neurological disorders. Yet, research into SD-related disorders has been hampered by the lack of non-invasive recording techniques of SD. Here we compared the manifestations of SD in continuous non-invasive electroencephalogram (EEG) recordings to invasive electrocorticographic (ECoG) recordings in order to obtain further insights into generator structures and electrogenic mechanisms of surface recording of SD. SD was induced by KCl application and simultaneous SD recordings were performed by scalp EEG as well as ECoG electrodes of somatosensory neocortex of rats using a novel homemade EEG amplifier, AgCl recording electrodes, and high chloride conductive gel. Different methods were used to analyze the data; including the spectrogram, bi-spectrogram, pattern distribution, relative spectrum power, and multivariable Gaussian fit analysis. The negative direct current (DC) shifts recorded by scalp electrodes exhibited a high homogeneity to those recorded by ECoG electrodes. Furthermore, this novel method of recording and analysis was able to separate SD recorded by scalp electrodes from non-neuronal DC shifts induced by other potential generators, such as the skin, muscles, arteries, dura, etc. These data suggest a novel application for continuous non-invasive monitoring of DC potential changes, such as SD. Non-invasive monitoring of SD would allow early intervention and improve outcome in SD-related neurological disorders. Copyright © 2016 IBRO. All rights reserved.

Neural complexity in patients with poststroke depression: A resting EEG study.

PubMed

Zhang, Ying; Wang, Chunfang; Sun, Changcheng; Zhang, Xi; Wang, Yongjun; Qi, Hongzhi; He, Feng; Zhao, Xin; Wan, Baikun; Du, Jingang; Ming, Dong

2015-12-01

Poststroke depression (PSD) is one of the most common emotional disorders affecting post-stroke patients. However, the neurophysiological mechanism remains elusive. This study was aimed to study the relationship between complexity of neural electrical activity and PSD. Resting state eye-closed electroencephalogram (EEG) signals of 16 electrodes were recorded in 21 ischemic poststroke depression (PSD) patients, 22 ischemic poststroke non-depression (PSND) patients and 15 healthy controls (CONT). Lempel-Ziv Complexity (LZC) was used to evaluate changes in EEG complexity in PSD patients. Statistical analysis was performed to explore difference among different groups and electrodes. Correlation between the severity of depression (HDRS) and EEG complexity was determined with pearson correlation coefficients. Receiver operating characteristic (ROC) and binary logistic regression analysis were conducted to estimate the discriminating ability of LZC for PSD in specificity, sensitivity and accuracy. PSD patients showed lower neural complexity compared with PSND and CONT subjects in the whole brain regions. There was no significant difference among different brain regions, and no interactions between group and electrodes. None of the LZC significantly correlated with overall depression severity or differentiated symptom severity of 7 items in PSD patients, but in stroke patients, significant correlation was found between HDRS and LZC in the whole brain regions, especially in frontal and temporal. LZC parameters used for PSD recognition possessed more than 85% in specificity, sensitivity and accuracy, suggesting the feasibility of LZC to serve as screening indicators for PSD. Increased slow wave rhythms were found in PSD patients and clearly correlation was confirmed between neuronal complexity and spectral power of the four EEG rhythms. Lesion location of stroke patients in the study distributed in different brain regions, and most of the PSD patients were mild or moderate in depressive severity. Compared with conventional spectral analysis, complexity of neural activity using LZC was more sensitive and stationary in the measurement of abnormal brain activity in PSD patients and may offer a potential approach to facilitate clinical screening of this disease. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Cocaine action on peripheral, non-monoamine neural substrates as a trigger of electroencephalographic desynchronization and electromyographic activation following i.v. administration in freely moving rats.

PubMed

Smirnov, M S; Kiyatkin, E A

2010-01-20

Many important physiological, behavioral and subjective effects of i.v. cocaine (COC) are exceptionally rapid and transient, suggesting a possible involvement of peripheral neural substrates in their triggering. In the present study, we used high-speed electroencephalographic (EEG) and electromyographic (EMG) recordings (4-s resolution) in freely moving rats to characterize the central electrophysiological effects of i.v. COC at low doses within a self-administration range (0.25-1.0 mg/kg). We found that COC induces rapid, strong, and prolonged desynchronization of cortical EEG (decrease in alpha and increase in beta and gamma activity) and activation of the neck EMG that begin within 2-6 s following the start of a 10-s injection; immediate components of both effects were dose-independent. The rapid effects of COC were mimicked by i.v. COC methiodide (COC-MET), a derivative that cannot cross the blood-brain barrier. At equimolar doses (0.33-1.33 mg/kg), COC-MET had equally fast and strong effects on EEG and EMG total powers, decreasing alpha and increasing beta and gamma activities. Rapid EEG desynchronization and EMG activation was also induced by i.v. procaine, a structurally similar, short-acting local anesthetic with virtually no effects on monoamine uptake; at equipotential doses (1.25-5.0 mg/kg), these effects were weaker and shorter in duration than those of COC. Surprisingly, i.v. saline injection delivered during slow-wave sleep (but not during quiet wakefulness) also induced a transient EEG desynchronization but without changes in EMG and motor activity; these effects were significantly weaker and much shorter than those induced by all tested drugs. These data suggest that in awake animals, i.v. COC induces rapid cortical activation and a subsequent motor response via its action on peripheral non-monoamine neural elements, involving neural transmission via visceral sensory pathways. By providing a rapid neural signal and triggering neural activation, such an action might play a crucial role in the sensory effects of COC, thus contributing to the learning and development of drug-taking behavior.

Performance and brain electrical activity during prolonged confinement.

PubMed

Lorenz, B; Lorenz, J; Manzey, D

1996-01-01

A subset of the AGARD-STRES battery including memory search, unstable tracking, and a combination of both tasks (dual-task), was applied repeatedly to the four chamber crew members before, during, and after the 60-day isolation period of EXEMSI. Five ground control group members served as a control group. A subjective state questionnaire was also included. The results were subjected to a quantitative single-subject analysis. Electroencephalograms (EEG) were recorded to permit correlation of changes in task performance with changes in the physiological state. Evaluation of the EEG focused on spectral parameters of spontaneous EEG waves. No physiological data were collected from the control group. Significant decrements in tracking ability were observed in the chamber crew. The time course of these effects followed a triphasic pattern with initial deterioration, intermediate recovery to pre-isolation baseline scores after the first half of the isolation period, and a second deterioration towards the end. None of the control group subjects displayed such an effect. Memory search (speed and accuracy) was only occasionally impaired during isolation, but the control group displayed a similar pattern of changes. It is suggested that a state of decreased alertness causes tracking deterioration, which leads to a reduced efficiency of sustained cue utilization. The assumption of low alertness was further substantiated by higher fatigue ratings by the chamber crew compared to those of the control group. Analysis of the continuous EEG recordings revealed that only two subjects produced reliable alpha wave activity (8-12 Hz) over Pz and, to a much smaller extent, Fz-theta wave activity (5-7 Hz) during task performance. In both subjects Pz-alpha power decreased consistently under task conditions involving single-task and dual-task tracking. Fz-theta activity was increased more by single-task and dual-task memory search than by single-task tracking. The alpha attenuation appears to be associated with an increasing demand on perceptual cue utilization required by the tracking performance. In one subject marked attenuation of alpha power occurred during the first half of the confinement period, where he also scored the highest fatigue ratings. A striking increase in fronto-central theta activity was observed in the same subject after six weeks of isolation. The change was associated with an efficient rather than a degraded task performance, and a high rating of the item "concentrated" and a low rating of the item "fatigued." This finding supports the hypothesis that the activation state associated with increased fronto-central theta activity accompanies efficient performance of demanding mental tasks. The usefulness of standardized laboratory tasks as monitoring instruments is demonstrated by the direct comparability with results of studies obtained from other relevant research applications using the same tasks. The feasibility of a self-administered integrated psychophysiological assessment of the individual state was illustrated by the nearly complete collection of data. The large number of individual data collected over the entire period permitted application of quantitative single-subject analysis, allowing reliable determination of changes in the individual state in the course of time. It thus appears that this assessment technique can be adapted for in-flight monitoring of astronauts during prolonged spaceflights. Parallel EEG recording can provide relevant supplementary information for diagnosing the individual activation state associated with task performance. The existence of large individual differences in the generation of task-sensitive EEG rhythms forms an important issue for further studies.

Baclofen-induced encephalopathy in overdose - Modeling of the electroencephalographic effect/concentration relationships and contribution of tolerance in the rat.

PubMed

Chartier, Magali; Malissin, Isabelle; Tannous, Salma; Labat, Laurence; Risède, Patricia; Mégarbane, Bruno; Chevillard, Lucie

2018-05-18

Baclofen, a γ-amino-butyric acid type-B receptor agonist with exponentially increased use at high-dose to facilitate abstinence in chronic alcoholics, is responsible for increasing poisonings. Baclofen overdose may induce severe encephalopathy and electroencephalographic (EEG) abnormalities. Whether prior prolonged baclofen treatment may influence the severity of baclofen-induced encephalopathy in overdose has not been established. We designed a rat study to characterize baclofen-induced encephalopathy, correlate its severity with plasma concentrations and investigate the contribution of tolerance. Baclofen-induced encephalopathy was assessed using continuous EEG and scored based on a ten-grade scale. Following the administration by gavage of 116 mg/kg baclofen, EEG rapidly and steadily impaired resulting in the successive onset of deepening sleep followed by generalized periodic epileptiform discharges and burst-suppressions. Thereafter, encephalopathy progressively recovered following similar phases in reverse. Periodic triphasic sharp waves, non-convulsive status epilepticus and even isoelectric signals were observed at the most critical stages. Prior repeated baclofen administration resulted in reduced severity (peak: grade 7 versus 9; peak effect length: 382 ± 40 versus 123 ± 14 min, P = 0.008) and duration of encephalopathy (18 versus > 24 h, P = 0.0007), supporting the acquisition of tolerance. The relationship between encephalopathy severity and plasma baclofen concentrations fitted a sigmoidal E max model with an anticlockwise hysteresis loop suggesting a hypothetical biophase site of action. The baclofen concentration producing a response equivalent to 50% of E max was significantly reduced (8947 μg/L, ±11.3% versus 12,728 μg/L, ±24.0% [mean, coefficient of variation], P = 0.03) with prior prolonged baclofen administration. In conclusion, baclofen overdose induces early-onset and prolonged marked encephalopathy that is significantly attenuated by prior repeated baclofen treatment. Our findings suggest a possible role for the blood-brain barrier in the development of tolerance; however, its definitive involvement remains to be demonstrated. Copyright © 2017. Published by Elsevier Inc.

Fast effects of glucocorticoids on memory-related network oscillations in the mouse hippocampus.

PubMed

Weiss, E K; Krupka, N; Bähner, F; Both, M; Draguhn, A

2008-05-01

Transient or lasting increases in glucocorticoids accompany deficits in hippocampus-dependent memory formation. Recent data indicate that the formation and consolidation of declarative and spatial memory are mechanistically related to different patterns of hippocampal network oscillations. These include gamma oscillations during memory acquisition and the faster ripple oscillations (approximately 200 Hz) during subsequent memory consolidation. We therefore analysed the effects of acutely applied glucocorticoids on network activity in mouse hippocampal slices. Evoked field population spikes and paired-pulse responses were largely unaltered by corticosterone or cortisol, respectively, despite a slight increase in maximal population spike amplitude by 10 microm corticosterone. Several characteristics of sharp waves and superimposed ripple oscillations were affected by glucocorticoids, most prominently the frequency of spontaneously occurring sharp waves. At 0.1 microm, corticosterone increased this frequency, whereas maximal (10 microm) concentrations led to a reduction. In addition, gamma oscillations became slightly faster and less regular in the presence of high doses of corticosteroids. The present study describes acute effects of glucocorticoids on sharp wave-ripple complexes and gamma oscillations in mouse hippocampal slices, revealing a potential background for memory deficits in the presence of elevated levels of these hormones.

On the initial value problem for the wave equation in Friedmann-Robertson-Walker space-times.

PubMed

Abbasi, Bilal; Craig, Walter

2014-09-08

The propagator W ( t 0 , t 1 )( g , h ) for the wave equation in a given space-time takes initial data ( g ( x ), h ( x )) on a Cauchy surface {( t , x ) :  t = t 0 } and evaluates the solution ( u ( t 1 , x ),∂ t u ( t 1 , x )) at other times t 1 . The Friedmann-Robertson-Walker space-times are defined for t 0 , t 1 >0, whereas for t 0 →0, there is a metric singularity. There is a spherical means representation for the general solution of the wave equation with the Friedmann-Robertson-Walker background metric in the three spatial dimensional cases of curvature K =0 and K =-1 given by S. Klainerman and P. Sarnak. We derive from the expression of their representation three results about the wave propagator for the Cauchy problem in these space-times. First, we give an elementary proof of the sharp rate of time decay of solutions with compactly supported data. Second, we observe that the sharp Huygens principle is not satisfied by solutions, unlike in the case of three-dimensional Minkowski space-time (the usual Huygens principle of finite propagation speed is satisfied, of course). Third, we show that for 0< t 0 < t the limit, [Formula: see text] exists, it is independent of h ( x ), and for all reasonable initial data g ( x ), it gives rise to a well-defined solution for all t >0 emanating from the space-time singularity at t =0. Under reflection t →- t , the Friedmann-Robertson-Walker metric gives a space-time metric for t <0 with a singular future at t =0, and the same solution formulae hold. We thus have constructed solutions u ( t , x ) of the wave equation in Friedmann-Robertson-Walker space-times which exist for all [Formula: see text] and [Formula: see text], where in conformally regularized coordinates, these solutions are continuous through the singularity t =0 of space-time, taking on specified data u (0,⋅)= g (⋅) at the singular time.

WOOLLY CUSPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nauenberg, M.; Pais, A.

1962-04-01

A study is made of the elastic scattering 1 + 2 yields 1 + 2 in the energy region where the inelastic process 1 + 2 yields 3 + 4 sets in, for the case that particle 3 is unstable. By woolly cusp'' is meant the phenomenon that corresponds to the sharp cusp in the stable case. The procedure followed is to consider the inelastic channel to be of the three-body type, where the three- body states are parametrized by a Breit-Wigner formula around a mean mass m of particle 3. The connection between a woolly and a sharp cuspmore » is made evident. The problem is studied in terms of a twochannel S-wave K matrix. In the two- channel approximation the woolly cusp necessarily shows a decrease in the elastic cross section sigma above a characteristic energy. As a function of energy, sigma must either show a maximum or an inflection point. In either case, the energy at which this happens may lie above or below the inelastic threshold for the fictitious case that particle 3 has a sharp mass m. The sign and magnitude of the elastic scattering phase shift at this m point'' approximately determines which case is actually realized. (auth)« less

Unexpected Occurrence of Mesospheric Frontal Gravity Wave Events Over South Pole (90°S)

NASA Astrophysics Data System (ADS)

Pautet, P.-D.; Taylor, M. J.; Snively, J. B.; Solorio, C.

2018-01-01

Since 2010, Utah State University has operated an infrared Advanced Mesospheric Temperature Mapper at the Amundsen-Scott South Pole station to investigate the upper atmosphere dynamics and temperature deep within the vortex. A surprising number of "frontal" gravity wave events (86) were recorded in the mesospheric OH(3,1) band intensity and rotational temperature images (typical altitude of 87 km) during four austral winters (2012-2015). These events are gravity waves (GWs) characterized by a sharp leading wave front followed by a quasi-monochromatic wave train that grows with time. A particular subset of frontal gravity wave events has been identified in the past (Dewan & Picard, 1998) as "bores." These are usually associated with wave ducting within stable mesospheric inversion layers, which allow them to propagate over very large distances. They have been observed on numerous occasions from low-latitude and midlatitude sites, but to date, very few have been reported at high latitudes. This study provides new analyses of the characteristics of frontal events at high latitudes and shows that most of them are likely ducted. The occurrence of these frontal GW events over this isolated region strongly supports the existence of horizontally extensive mesospheric thermal inversion layers over Antarctica, leading to regions of enhanced stability necessary for GW trapping and ducting.

LGI1 microdeletion in autosomal dominant lateral temporal epilepsy

PubMed Central

Fanciulli, M.; Santulli, L.; Errichiello, L.; Barozzi, C.; Tomasi, L.; Rigon, L.; Cubeddu, T.; de Falco, A.; Rampazzo, A.; Michelucci, R.; Uzzau, S.; Striano, S.; de Falco, F.A.; Striano, P.

2012-01-01

Objectives: To characterize clinically and genetically a family with autosomal dominant lateral temporal epilepsy (ADLTE) negative to LGI1 exon sequencing test. Methods: All participants were personally interviewed and underwent neurologic examination. Most affected subjects underwent EEG and neuroradiologic examinations (CT/MRI). Available family members were genotyped with the HumanOmni1-Quad v1.0 single nucleotide polymorphism (SNP) array beadchip and copy number variations (CNVs) were analyzed in each subject. LGI1 gene dosage was performed by real-time quantitative PCR (qPCR). Results: The family had 8 affected members (2 deceased) over 3 generations. All of them showed GTC seizures, with focal onset in 6 and unknown onset in 2. Four patients had focal seizures with auditory features. EEG showed only minor sharp abnormalities in 3 patients and MRI was unremarkable in all the patients examined. Three family members presented major depression and anxiety symptoms. Routine LGI1 exon sequencing revealed no point mutation. High-density SNP array CNV analysis identified a genomic microdeletion about 81 kb in size encompassing the first 4 exons of LGI1 in all available affected members and in 2 nonaffected carriers, which was confirmed by qPCR analysis. Conclusions: This is the first microdeletion affecting LGI1 identified in ADLTE. Families with ADLTE in which no point mutations are revealed by direct exon sequencing should be screened for possible genomic deletion mutations by CNV analysis or other appropriate methods. Overall, CNV analysis of multiplex families may be useful for identifying microdeletions in novel disease genes. PMID:22496201

Investigation of standing wave formation in a human skull for a clinical prototype of a large-aperture, transcranial MR-guided Focused Ultrasound (MRgFUS) phased array: An experimental and simulation study

PubMed Central

Song, Junho; Pulkkinen, Aki; Huang, Yuexi; Hynynen, Kullervo

2014-01-01

Standing wave formation in an ex vivo human skull was investigated using a clinical prototype of a 30 cm diameter with 15 cm radius of curvature, low frequency (230 kHz), hemispherical transcranial Magnetic Resonance guided Focused Ultrasound (MRgFUS) phased-array. Experimental and simulation studies were conducted with changing aperture size and f-number configurations of the phased array, and qualitatively and quantitatively examined the acoustic pressure variation at the focus due to standing waves. The results demonstrated that the nodes and anti-nodes of standing wave produced by the small aperture array were clearly seen at approximately every 3 mm. The effect of the standing wave became more pronounced as the focus was moved closer to skull base. However, a sharp focus was seen for the full array, and there was no such standing wave pattern in the acoustic plane or near the skull base. This study showed that the fluctuation pressure amplitude would be greatly reduced by using a large-scale, hemispherical phased array with a low f-number. PMID:22049360

Laser beat wave excitation of terahertz radiation in a plasma slab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chauhan, Santosh; Parashar, Jetendra, E-mail: j.p.parashar@gmail.com

2014-10-15

Terahertz (THz) radiation generation by nonlinear mixing of lasers, obliquely incident on a plasma slab is investigated. Two cases are considered: (i) electron density profile is parabolic but density peak is below the critical density corresponding to the beat frequency, (ii) plasma boundaries are sharp and density is uniform. In both cases, nonlinearity arises through the ponderomotive force that gives rise to electron drift at the beat frequency. In the case of inhomogeneous plasma, non zero curl of the nonlinear current density gives rise to electromagnetic THz generation. In case of uniform plasma, the sharp density variation at the plasmamore » boundaries leads to radiation generation. In a slab width of less than a terahertz wavelength, plasma density one fourth of terahertz critical density, laser intensities ∼10{sup 17 }W/cm{sup 2} at 1 μm, one obtains the THz intensity ∼1 GW/cm{sup 2} at 3 THz radiation frequency.« less

Existence and Stability of Traveling Waves for Degenerate Reaction-Diffusion Equation with Time Delay

NASA Astrophysics Data System (ADS)

Huang, Rui; Jin, Chunhua; Mei, Ming; Yin, Jingxue

2018-01-01

This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction-diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of c≥c^* for the degenerate reaction-diffusion equation without delay, where c^*>0 is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay τ >0 . Furthermore, we prove the global existence and uniqueness of C^{α ,β } -solution to the time-delayed degenerate reaction-diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted L^1 -space. The exponential convergence rate is also derived.

Schottky's conjecture on multiplication of field enhancement factors

NASA Astrophysics Data System (ADS)

Miller, Ryan; Lau, Y. Y.; Booske, John H.

2009-11-01

Of great interest to high power microwave, millimeter wave to terahertz sources, x-ray tubes, electrons guns, etc., is the electric field enhancement obtained from sharp emitting structures fabricated by various microfabrication methods. In this paper, we use conformal mapping to investigate the field enhancement of several rectilinear geometries, including a single rectangular ridge, a trapezoidal ridge, and their superposition, i.e., one ridge on top of another. We show that the composite field enhancement factor of the double ridge with a microprotrusion on top of a macroprotrusion is dominated by the product of the individual protrusions' field enhancement factors over a very wide range of geometric aspect ratios, as conjectured by Schottky. Simplified scaling laws are proposed. Significant deviation from Schottky's product rule occurs almost exclusively when the half-width of the macroprotrusion is less than the height of the microprotrusion. Accurate expressions of the divergent electric field near the sharp edges are derived.

Electronic Transport and Possible Superconductivity at Van Hove Singularities in Carbon Nanotubes.

PubMed

Yang, Y; Fedorov, G; Shafranjuk, S E; Klapwijk, T M; Cooper, B K; Lewis, R M; Lobb, C J; Barbara, P

2015-12-09

Van Hove singularities (VHSs) are a hallmark of reduced dimensionality, leading to a divergent density of states in one and two dimensions and predictions of new electronic properties when the Fermi energy is close to these divergences. In carbon nanotubes, VHSs mark the onset of new subbands. They are elusive in standard electronic transport characterization measurements because they do not typically appear as notable features and therefore their effect on the nanotube conductance is largely unexplored. Here we report conductance measurements of carbon nanotubes where VHSs are clearly revealed by interference patterns of the electronic wave functions, showing both a sharp increase of quantum capacitance, and a sharp reduction of energy level spacing, consistent with an upsurge of density of states. At VHSs, we also measure an anomalous increase of conductance below a temperature of about 30 K. We argue that this transport feature is consistent with the formation of Cooper pairs in the nanotube.

Time-frequency dynamics during sleep spindles on the EEG in rodents with a genetic predisposition to absence epilepsy (WAG/Rij rats)

NASA Astrophysics Data System (ADS)

Hramov, Alexander E.; Sitnikova, Evgenija Y.; Pavlov, Alexey N.; Grubov, Vadim V.; Koronovskii, Alexey A.; Khramova, Marina V.

2015-03-01

Sleep spindles are known to appear spontaneously in the thalamocortical neuronal network of the brain during slow-wave sleep; pathological processes in the thalamocortical network may be the reason of the absence epilepsy. The aim of the present work is to study developed changes in the time-frequency structure of sleep spindles during the progressive development of the absence epilepsy in WAG/Rij rats. EEG recordings were made at age 7 and 9 months. Automatic recognition and subsequent analysis of sleep spindles on the EEG were performed using the continuous wavelet transform. The duration of epileptic discharges and the total duration of epileptic activity were found to increase with age, while the duration of sleep spindles, conversely, decreased. In terms of the mean frequency, sleep spindles could be divided into three classes: `slow' (mean frequency 9.3Hz), `medium' (11.4Hz), and `fast' (13.5Hz). Slow and medium (transitional) spindles in five-month-old animals showed increased frequency from the beginning to the end of the spindle. The more intense the epilepsy is, the shorter are the durations of spindles of all types. The mean frequencies of `medium' and `fast' spindles were higher in rats with more intense signs of epilepsy. Overall, high epileptic activity in WAG/Rij rats was linked with significant changes in spindles of the transitional type, with less marked changes in the two traditionally identified types of spindle, slow and fast.

Electrophysiological Responses to Alcohol Cues Are Not Associated with Pavlovian-to-Instrumental Transfer in Social Drinkers

PubMed Central

Martinovic, Jasna; Jones, Andrew; Christiansen, Paul; Rose, Abigail K.; Hogarth, Lee; Field, Matt

2014-01-01

Pavlovian to Instrumental Transfer (PIT) refers to the behavioral phenomenon of increased instrumental responding for a reinforcer when in the presence of Pavlovian conditioned stimuli that were separately paired with that reinforcer. PIT effects may play an important role in substance use disorders, but little is known about the brain mechanisms that underlie these effects in alcohol consumers. We report behavioral and electroencephalographic (EEG) data from a group of social drinkers (n = 31) who performed a PIT task in which they chose between two instrumental responses in pursuit of beer and chocolate reinforcers while their EEG reactivity to beer, chocolate and neutral pictorial cues was recorded. We examined two markers of the motivational salience of the pictures: the P300 and slow wave event-related potentials (ERPs). Results demonstrated a behavioral PIT effect: responding for beer was increased when a beer picture was presented. Analyses of ERP amplitudes demonstrated significantly larger slow potentials evoked by beer cues at various electrode clusters. Contrary to hypotheses, there were no significant correlations between behavioral PIT effects, electrophysiological reactivity to the cues, and individual differences in drinking behaviour. Our findings are the first to demonstrate a PIT effect for beer, accompanied by increased slow potentials in response to beer cues, in social drinkers. The lack of relationship between behavioral and EEG measures, and between these measures and individual differences in drinking behaviour may be attributed to methodological features of the PIT task and to characteristics of our sample. PMID:24732090

Pharmacokinetic and pharmacodynamic effects of clonazepam in children with epilepsy treated with valproate: a preliminary study.

PubMed

Wang, Li; Wang, Xiao-Dong

2002-08-01

The authors report the use of the quantitative pharmaco-EEG (QPEEG) technique to study the pharmacokinetics (PK) and pharmacodynamics (PD) of clonazepam (CZP) in four epileptic children who suffered uncontrolled seizures despite long-term valproate (VPA) therapy. After a single dose of CZP (0.05 mg/kg, PO), blood samples were collected at 0, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 8.0, 12.0, and 24.0 hours. CZP and VPA concentrations were measured by HPLC or GC assay, respectively. At each blood collection time point, EEG signals (60 s) were recorded for brain electrical activity mapping, and the power percentage average (PPA) of each frequency band was calculated. The relationship between drug concentrations and their corresponding PPA of each frequency band was analyzed. VPA steady-state drug concentrations (Css) were within the therapeutic range and not affected by CZP. The peak concentration (Cmax) of CZP and the time intervals from dosing to Cmax (Tmax) were 20.9 ng/mL to 113.8 ng/mL and 1 hour to 1.5 hours, respectively. There was no significant correlation between VPA concentrations and the PPA of any of the EEG frequency bands. CZP blood concentrations showed significant correlation with PPA in 3 of the 4 patients. Our results suggested CZP could affect fast wave activities in proportion to CZP blood concentrations. We propose that QPEEG is a promising technique to study the PK and PD of selected anti-epileptic drugs.

Existence and Stability of Traveling Waves for Degenerate Reaction-Diffusion Equation with Time Delay

NASA Astrophysics Data System (ADS)

Huang, Rui; Jin, Chunhua; Mei, Ming; Yin, Jingxue

2018-06-01

This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction-diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of c≥c^* for the degenerate reaction-diffusion equation without delay, where c^*>0 is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay τ >0. Furthermore, we prove the global existence and uniqueness of C^{α ,β }-solution to the time-delayed degenerate reaction-diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted L^1-space. The exponential convergence rate is also derived.

The quasi 2 day wave response in TIME-GCM nudged with NOGAPS-ALPHA

NASA Astrophysics Data System (ADS)

Wang, Jack C.; Chang, Loren C.; Yue, Jia; Wang, Wenbin; Siskind, D. E.

2017-05-01

The quasi 2 day wave (QTDW) is a traveling planetary wave that can be enhanced rapidly to large amplitudes in the mesosphere and lower thermosphere (MLT) region during the northern winter postsolstice period. In this study, we present five case studies of QTDW events during January and February 2005, 2006 and 2008-2010 by using the Thermosphere-Ionosphere-Mesosphere Electrodynamics-General Circulation Model (TIME-GCM) nudged with the Navy Operational Global Atmospheric Prediction System-Advanced Level Physics High Altitude (NOGAPS-ALPHA) Weather Forecast Model. With NOGAPS-ALPHA introducing more realistic lower atmospheric forcing in TIME-GCM, the QTDW events have successfully been reproduced in the TIME-GCM. The nudged TIME-GCM simulations show good agreement in zonal mean state with the NOGAPS-ALPHA 6 h reanalysis data and the horizontal wind model below the mesopause; however, it has large discrepancies in the tropics above the mesopause. The zonal mean zonal wind in the mesosphere has sharp vertical gradients in the nudged TIME-GCM. The results suggest that the parameterized gravity wave forcing may need to be retuned in the assimilative TIME-GCM.

Nonlinear dynamics of a two-dimensional Wigner solid on superfluid helium

NASA Astrophysics Data System (ADS)

Monarkha, Yu. P.

2018-04-01

Nonlinear dynamics and transport properties of a 2D Wigner solid (WS) on the free surface of superfluid helium are theoretically studied. The analysis is nonperturbative in the amplitude of the WS velocity. An anomalous nonlinear response of the liquid helium surface to the oscillating motion of the WS is shown to appear when the driving frequency is close to subharmonics of the frequency of a capillary wave (ripplon) whose wave vector coincides with a reciprocal-lattice vector. As a result, the effective mass of surface dimples formed under electrons and the kinetic friction acquire sharp anomalies in the low-frequency range, which affects the mobility and magnetoconductivity of the WS. The results obtained here explain a variety of experimental observations reported previously.

Manipulation of peripheral neural feedback loops alters human corticomuscular coherence

PubMed Central

Riddle, C Nicholas; Baker, Stuart N

2005-01-01

Sensorimotor EEG shows ∼20 Hz coherence with contralateral EMG. This could involve efferent and/or afferent components of the sensorimotor loop. We investigated the pathways responsible for coherence genesis by manipulating nervous conduction delays using cooling. Coherence between left sensorimotor EEG and right EMG from three hand and two forearm muscles was assessed in healthy subjects during the hold phase of a precision grip task. The right arm was then cooled to 10°C for ∼90 min, increasing peripheral motor conduction time (PMCT) by ∼35% (assessed by F-wave latency). EEG and EMG recordings were repeated, and coherence recalculated. Control recordings revealed a heterogeneous subject population. In 6/15 subjects (Group A), the corticomuscular coherence phase increased linearly with frequency, as expected if oscillations were propagated along efferent pathways from cortex to muscle. The mean corticomuscular conduction delay for intrinsic hand muscles calculated from the phase–frequency regression slope was 10.4 ms; this is smaller than the delay expected for conduction over fast corticospinal pathways. In 8/15 subjects (Group B), the phase showed no dependence with frequency. One subject showed both Group A and Group B patterns over different frequency ranges. Following cooling, averaged corticomuscular coherence was decreased in Group A subjects, but unchanged for Group B, even though both groups showed comparable slowing of nervous conduction. The delay calculated from the slope of the phase–frequency regression was increased following cooling. However, the size of this increase was around twice the rise in PMCT measured using the F-wave (regression slope 2.33, 95% confidence limits 1.30–3.36). Both afferent and efferent peripheral nerves will be slowed by similar amounts following cooling. The change in delay calculated from the coherence phase therefore better matches the rise in total sensorimotor feedback loop time caused by cooling, rather than just the change in the efferent limb. A model of corticomuscular coherence which assumes that only efferent pathways contribute cannot be reconciled to these results. The data rather suggest that afferent feedback pathways may also play a role in the genesis of corticomuscular coherence. PMID:15919711

Finite-surface method for the Maxwell equations with corner singularities

NASA Technical Reports Server (NTRS)

Vinokur, Marcel; Yarrow, Maurice

1994-01-01

The finite-surface method for the two-dimensional Maxwell equations in generalized coordinates is extended to treat perfect conductor boundaries with sharp corners. Known singular forms of the grid and the electromagnetic fields in the neighborhood of each corner are used to obtain accurate approximations to the surface and line integrals appearing in the method. Numerical results are presented for a harmonic plane wave incident on a finite flat plate. Comparisons with exact solutions show good agreement.

Electroencephalography as a Tool for Assessment of Brain Ischemic Alterations after Open Heart Operations

PubMed Central

Golukhova, Elena Z.; Polunina, Anna G.; Lefterova, Natalia P.; Begachev, Alexey V.

2011-01-01

Cardiac surgery is commonly associated with brain ischemia. Few studies addressed brain electric activity changes after on-pump operations. Eyes closed EEG was performed in 22 patients (mean age: 45.2 ± 11.2) before and two weeks after valve replacement. Spouses of patients were invited to participate as controls. Generalized increase of beta power most prominent in beta-1 band was an unambiguous pathological sign of postoperative cortex dysfunction, probably, manifesting due to gamma-activity slowing (“beta buzz” symptom). Generalized postoperative increase of delta-1 mean frequency along with increase of slow-wave activity in right posterior region may be hypothesized to be a consequence of intraoperative ischemia as well. At the same time, significant changes of alpha activity were observed in both patient and control groups, and, therefore, may be considered as physiological. Unexpectedly, controls showed prominent increase of electric activity in left temporal region whereas patients were deficient in left hemisphere activity in comparison with controls at postoperative followup. Further research is needed in order to determine the true neurological meaning of the EEG findings after on-pump operations. PMID:21776370

Disruption of perineuronal nets increases the frequency of sharp wave ripple events.

PubMed

Sun, Zhi Yong; Bozzelli, P Lorenzo; Caccavano, Adam; Allen, Megan; Balmuth, Jason; Vicini, Stefano; Wu, Jian-Young; Conant, Katherine

2018-01-01

Hippocampal sharp wave ripples (SWRs) represent irregularly occurring synchronous neuronal population events that are observed during phases of rest and slow wave sleep. SWR activity that follows learning involves sequential replay of training-associated neuronal assemblies and is critical for systems level memory consolidation. SWRs are initiated by CA2 or CA3 pyramidal cells (PCs) and require initial excitation of CA1 PCs as well as participation of parvalbumin (PV) expressing fast spiking (FS) inhibitory interneurons. These interneurons are relatively unique in that they represent the major neuronal cell type known to be surrounded by perineuronal nets (PNNs), lattice like structures composed of a hyaluronin backbone that surround the cell soma and proximal dendrites. Though the function of the PNN is not completely understood, previous studies suggest it may serve to localize glutamatergic input to synaptic contacts and thus influence the activity of ensheathed cells. Noting that FS PV interneurons impact the activity of PCs thought to initiate SWRs, and that their activity is critical to ripple expression, we examine the effects of PNN integrity on SWR activity in the hippocampus. Extracellular recordings from the stratum radiatum of horizontal murine hippocampal hemisections demonstrate SWRs that occur spontaneously in CA1. As compared with vehicle, pre-treatment (120 min) of paired hemislices with hyaluronidase, which cleaves the hyaluronin backbone of the PNN, decreases PNN integrity and increases SWR frequency. Pre-treatment with chondroitinase, which cleaves PNN side chains, also increases SWR frequency. Together, these data contribute to an emerging appreciation of extracellular matrix as a regulator of neuronal plasticity and suggest that one function of mature perineuronal nets could be to modulate the frequency of SWR events. © 2017 Wiley Periodicals, Inc.

Optimizing detection and analysis of slow waves in sleep EEG.

PubMed

Mensen, Armand; Riedner, Brady; Tononi, Giulio

2016-12-01

Analysis of individual slow waves in EEG recording during sleep provides both greater sensitivity and specificity compared to spectral power measures. However, parameters for detection and analysis have not been widely explored and validated. We present a new, open-source, Matlab based, toolbox for the automatic detection and analysis of slow waves; with adjustable parameter settings, as well as manual correction and exploration of the results using a multi-faceted visualization tool. We explore a large search space of parameter settings for slow wave detection and measure their effects on a selection of outcome parameters. Every choice of parameter setting had some effect on at least one outcome parameter. In general, the largest effect sizes were found when choosing the EEG reference, type of canonical waveform, and amplitude thresholding. Previously published methods accurately detect large, global waves but are conservative and miss the detection of smaller amplitude, local slow waves. The toolbox has additional benefits in terms of speed, user-interface, and visualization options to compare and contrast slow waves. The exploration of parameter settings in the toolbox highlights the importance of careful selection of detection METHODS: The sensitivity and specificity of the automated detection can be improved by manually adding or deleting entire waves and or specific channels using the toolbox visualization functions. The toolbox standardizes the detection procedure, sets the stage for reliable results and comparisons and is easy to use without previous programming experience. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrophysiological responses to alcohol cues are not associated with Pavlovian-to-instrumental transfer in social drinkers.

PubMed

Martinovic, Jasna; Jones, Andrew; Christiansen, Paul; Rose, Abigail K; Hogarth, Lee; Field, Matt

2014-01-01

Pavlovian to Instrumental Transfer (PIT) refers to the behavioral phenomenon of increased instrumental responding for a reinforcer when in the presence of Pavlovian conditioned stimuli that were separately paired with that reinforcer. PIT effects may play an important role in substance use disorders, but little is known about the brain mechanisms that underlie these effects in alcohol consumers. We report behavioral and electroencephalographic (EEG) data from a group of social drinkers (n = 31) who performed a PIT task in which they chose between two instrumental responses in pursuit of beer and chocolate reinforcers while their EEG reactivity to beer, chocolate and neutral pictorial cues was recorded. We examined two markers of the motivational salience of the pictures: the P300 and slow wave event-related potentials (ERPs). Results demonstrated a behavioral PIT effect: responding for beer was increased when a beer picture was presented. Analyses of ERP amplitudes demonstrated significantly larger slow potentials evoked by beer cues at various electrode clusters. Contrary to hypotheses, there were no significant correlations between behavioral PIT effects, electrophysiological reactivity to the cues, and individual differences in drinking behaviour. Our findings are the first to demonstrate a PIT effect for beer, accompanied by increased slow potentials in response to beer cues, in social drinkers. The lack of relationship between behavioral and EEG measures, and between these measures and individual differences in drinking behaviour may be attributed to methodological features of the PIT task and to characteristics of our sample.

Electric stimulation of the tuberomamillary nucleus affects epileptic activity and sleep-wake cycle in a genetic absence epilepsy model.

PubMed

Blik, Vitaliya

2015-01-01

Deep brain stimulation (DBS) is a promising approach for epilepsy treatment, but the optimal targets and parameters of stimulation are yet to be investigated. Tuberomamillary nucleus (TMN) is involved in EEG desynchronization-one of the proposed mechanisms for DBS action. We studied whether TMN stimulation could interfere with epileptic spike-wave discharges (SWDs) in WAG/Rij rats with inherited absence epilepsy and whether such stimulation would affect sleep-wake cycle. EEG and video registration were used to determine SWD occurrence and stages of sleep and wake during three-hours recording sessions. Stimulation (100Hz) was applied in two modes: closed-loop (with previously determined interruption threshold intensity) or open-loop mode (with 50% or 70% threshold intensity). Closed-loop stimulation successfully interrupted SWDs but elevated their number by 148 ± 54% compared to baseline. It was accompanied by increase in number of episodes but not total duration of both active and passive wakefulness. Open-loop stimulation with amplitude 50% threshold did not change measured parameters, though 70% threshold stimulation reduced SWDs number by 40 ± 9%, significantly raised the amount of active wakefulness and decreased the amount of both slow-wave and rapid eye movement sleep. These results suggest that the TMN is unfavorable as a target for DBS as its stimulation may cause alterations in sleep-wake cycle. A careful choosing of parameters and control of sleep-wake activity is necessary when applying DBS in epilepsy. Copyright © 2014 Elsevier B.V. All rights reserved.

Ketamine, sleep, and depression: current status and new questions.

PubMed

Duncan, Wallace C; Zarate, Carlos A

2013-09-01

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has well-described rapid antidepressant effects in clinical studies of individuals with treatment-resistant major depressive disorder (MDD). Preclinical studies investigating the effects of ketamine on brain-derived neurotrophic factor (BDNF) and on sleep slow wave activity (SWA) support its use as a prototype for investigating the neuroplastic mechanisms presumably involved in the mechanism of rapidly acting antidepressants. This review discusses human EEG slow wave sleep parameters and plasma BDNF as central and peripheral surrogate markers of plasticity, and their use in assessing ketamine's effects. Acutely, ketamine elevates BDNF levels, as well as early night SWA and high-amplitude slow waves; each of these measures correlates with change in mood in depressed patients who respond to ketamine. The slow wave effects are limited to the first night post-infusion, suggesting that their increase is part of an early cascade of events triggering improved mood. Increased total sleep and decreased waking occur during the first and second night post infusion, suggesting that these measures are associated with the enduring treatment response observed with ketamine.

Impaired consciousness in patients with absence seizures investigated by functional MRI, EEG, and behavioural measures: a cross-sectional study.

PubMed

Guo, Jennifer N; Kim, Robert; Chen, Yu; Negishi, Michiro; Jhun, Stephen; Weiss, Sarah; Ryu, Jun Hwan; Bai, Xiaoxiao; Xiao, Wendy; Feeney, Erin; Rodriguez-Fernandez, Jorge; Mistry, Hetal; Crunelli, Vincenzo; Crowley, Michael J; Mayes, Linda C; Constable, R Todd; Blumenfeld, Hal

2016-12-01

The neural underpinnings of impaired consciousness and of the variable severity of behavioural deficits from one absence seizure to the next are not well understood. We aimed to measure functional MRI (fMRI) and electroencephalography (EEG) changes in absence seizures with impaired task performance compared with seizures in which performance was spared. In this cross-sectional study done at the Yale School of Medicine, CT, USA, we recruited patients from 59 paediatric neurology practices in the USA. We did simultaneous EEG, fMRI, and behavioural testing in patients aged 6-19 years with childhood or juvenile absence epilepsy, and with an EEG with typical 3-4 Hz bilateral spike-wave discharges and normal background. The main outcomes were fMRI and EEG amplitudes in seizures with impaired versus spared behavioural responses analysed by t test. We also examined the timing of fMRI and EEG changes in seizures with impaired behavioural responses compared with seizures with spared responses. 93 patients were enrolled between Jan 1, 2005, and Sept 1, 2013; we recorded 1032 seizures in 39 patients. fMRI changes during seizures occurred sequentially in three functional brain networks. In the default mode network, fMRI amplitude was 0·57% (SD 0·26) for seizures with impaired and 0·40% (0·16) for seizures with spared behavioural responses (mean difference 0·17%, 95% CI 0·11-0·23; p<0·0001). In the task-positive network, fMRI amplitude was 0·53% (SD 0·29) for seizures with impaired and 0·39% (0·15) for seizures with spared behavioral responses (mean difference 0·14%, 95% CI 0·08-0·21; p<0·0001). In the sensorimotor-thalamic network, fMRI amplitude was 0·41% (0·25) for seizures with impaired and 0·34% (0·14) for seizures with spared behavioural responses (mean difference 0·07%, 95% CI 0·01-0·13; p=0·02). Mean fractional EEG power in the frontal leads was 50·4 (SD 15·2) for seizures with impaired and 24·8 (6·5) for seizures with spared behavioural responses (mean difference 25·6, 95% CI 21·0-30·3); middle leads 35·4 (6·5) for seizures with impaired, 13·3 (3·4) for seizures with spared behavioural responses (mean difference 22·1, 95% CI 20·0-24·1); posterior leads 41·6 (5·3) for seizures with impaired, 24·6 (8·6) for seizures with spared behavioural responses (mean difference 17·0, 95% CI 14·4-19·7); p<0·0001 for all comparisons. Mean seizure duration was longer for seizures with impaired behaviour at 7·9 s (SD 6·6), compared with 3·8 s (3·0) for seizures with spared behaviour (mean difference 4·1 s, 95% CI 3·0-5·3; p<0·0001). However, larger amplitude fMRI and EEG signals occurred at the outset or even preceding seizures with behavioural impairment. Impaired consciousness in absence seizures is related to the intensity of physiological changes in established networks affecting widespread regions of the brain. Increased EEG and fMRI amplitude occurs at the onset of seizures associated with behavioural impairment. These finding suggest that a vulnerable state might exist at the initiation of some absence seizures leading them to have more severe physiological changes and altered consciousness than other absence seizures. National Institutes of Health, National Institute of Neurological Disorders and Stroke, National Center for Advancing Translational Science, the Loughridge Williams Foundation, and the Betsy and Jonathan Blattmachr Family. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamic groundwater flows and geochemistry in a sandy nearshore aquifer over a wave event

NASA Astrophysics Data System (ADS)

Malott, Spencer; O'Carroll, Denis M.; Robinson, Clare E.

2016-07-01

Dynamic coastal forcing influences the transport of pollutants in nearshore aquifers and their ultimate flux to coastal waters. In this study, field data are presented that show, for the first time, the influence of a period of intensified wave conditions (wave event) on nearshore groundwater flows and geochemistry in a sandy beach. Field measurements at a freshwater beach allow wave effects to be quantified without other complex forcing that are present along marine shorelines (e.g., tides). Pressure transducer data obtained over an isolated wave event reveal the development of transient groundwater flow recirculations. The groundwater flows were simulated in FEFLOW using a phase-averaged wave setup approach to represent waves acting on the sediment-water interface. Comparison of measured and simulated data indicates that consideration of wave setup alone is able to adequately capture wave-induced perturbations in groundwater flows. While prior studies have shown sharp pH and redox spatial zonations in nearshore aquifers, this study reveals rapid temporal variations in conductivity, pH, and redox (ORP) in shallow sediments (up to 0.5 m depth) in response to varying wave conditions. Comparison of head gradients with calculated conductivity and pH mixing ratios indicates the controlling effect of the wave-induced water exchange and flows in driving the observed geochemical dynamics. While we are not able to conclusively determine the extent to which temporal variations are caused by conservative mixing versus reactive processes, the pH and ORP variations observed will have significant implications for the fate of reactive pollutants discharging through sandy nearshore aquifers.

Slow spontaneous hemodynamic oscillations during sleep measured with near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Virtanen, Jaakko; Näsi, Tiina; Noponen, Tommi; Toppila, Jussi; Salmi, Tapani; Ilmoniemi, Risto J.

2011-07-01

Spontaneous cerebral hemodynamic oscillations below 100 mHz reflect the level of cerebral activity, modulate hemodynamic responses to tasks and stimuli, and may aid in detecting various pathologies of the brain. Near-infrared spectroscopy (NIRS) is ideally suited for both measuring spontaneous hemodynamic oscillations and monitoring sleep, but little research has been performed to combine these two applications. We analyzed 30 all-night NIRS-electroencephalography (EEG) sleep recordings to investigate spontaneous hemodynamic activity relative to sleep stages determined by polysomnography. Signal power of hemodynamic oscillations in the low-frequency (LF, 40-150 mHz) and very-low-frequency (VLF, 3-40 mHz) bands decreased in slow-wave sleep (SWS) compared to light sleep (LS) and rapid-eye-movement (REM) sleep. No statistically significant (p < 0.05) differences in oscillation power between LS and REM were observed. However, the period of VLF oscillations around 8 mHz increased in REM sleep in line with earlier studies with other modalities. These results increase our knowledge of the physiology of sleep, complement EEG data, and demonstrate the applicability of NIRS to studying spontaneous hemodynamic fluctuations during sleep.

Evaluation of nonlinear properties of epileptic activity using largest Lyapunov exponent

NASA Astrophysics Data System (ADS)

Medvedeva, Tatiana M.; Lüttjohann, Annika; van Luijtelaar, Gilles; Sysoev, Ilya V.

2016-04-01

Absence seizures are known to be highly non-linear large amplitude oscillations with a well pronounced main time scale. Whilst the appearance of the main frequency is usually considered as a transition from noisy complex dynamics of baseline EEG to more regular absence activity, the dynamical properties of this type of epileptiformic activity in genetic absence models was not studied precisely. Here, the estimation of the largest Lyapunov exponent from intracranial EEGs of 10 WAG/Rij rats (genetic model of absence epilepsy) was performed. Fragments of 10 seizures and 10 episodes of on-going EEG each of 4 s length were used for each animal, 3 cortical and 2 thalamic channels were analysed. The method adapted for short noisy data was implemented. The positive values of the largest Lyapunov exponent were found as for baseline as for spike wave discharges (SWDs), with values for SWDs being significantly less than for on-going activity. Current findings may indicate that SWD is a chaotic process with a well pronounced main timescale rather than a periodic regime. Also, the absence activity was shown to be less chaotic than the baseline one.

Sleep in the domestic hen (Gallus domesticus).

PubMed

van Luijtelaar, E L; van der Grinten, C P; Blokhuis, H J; Coenen, A M

1987-01-01

Electrophysiological recordings were made of five closely observed hens, all permanently implanted with both EEG and EMG electrodes. Five behavioural postures were distinguished and percentages of wakefulness, sleep and presumably paradoxical sleep (PS) were determined during the third and sixth hour of the dark period. Substantial agreement was generally found between behaviour and sleep with the exception of sitting or standing motionless with at least one eye open. During two thirds of this behavioural posture, the EEG showed large amplitude slow waves undistinguishable from slow wave sleep. Characteristics of PS were determined: periods were short, whereas its percentage increased during the night. Furthermore, EMG atonia was never found. An all night recording was made, and delta activity (2-5 Hz) was filtered and plotted against time for three of the hens. A significant decrease in delta activity across the night was found. Differences and similarities between sleep in hens and in mammals are discussed. Although large similarities exist it is concluded that some properties of birds' sleep make it unique and are a challenge for further study.

Amplitude Integrated Electroencephalography Compared With Conventional Video EEG for Neonatal Seizure Detection: A Diagnostic Accuracy Study.

PubMed

Rakshasbhuvankar, Abhijeet; Rao, Shripada; Palumbo, Linda; Ghosh, Soumya; Nagarajan, Lakshmi

2017-08-01

This diagnostic accuracy study compared the accuracy of seizure detection by amplitude-integrated electroencephalography with the criterion standard conventional video EEG in term and near-term infants at risk of seizures. Simultaneous recording of amplitude-integrated EEG (2-channel amplitude-integrated EEG with raw trace) and video EEG was done for 24 hours for each infant. Amplitude-integrated EEG was interpreted by a neonatologist; video EEG was interpreted by a neurologist independently. Thirty-five infants were included in the analysis. In the 7 infants with seizures on video EEG, there were 169 seizure episodes on video EEG, of which only 57 were identified by amplitude-integrated EEG. Amplitude-integrated EEG had a sensitivity of 33.7% for individual seizure detection. Amplitude-integrated EEG had an 86% sensitivity for detection of babies with seizures; however, it was nonspecific, in that 50% of infants with seizures detected by amplitude-integrated EEG did not have true seizures by video EEG. In conclusion, our study suggests that amplitude-integrated EEG is a poor screening tool for neonatal seizures.

Local strong slow S-wave anomalies at western edge of Pacific LLSVP

NASA Astrophysics Data System (ADS)

Obayashi, M.; Niu, F.; Yoshimitsu, J.

2017-12-01

Seismic tomography studies have revealed two broad slow shear-wave speed anomalies regions beneath the Pacific and Africa called as LLSVPs (Large Low Seismic Velocity Provinces). There are geographic correlations between the LLSVPs and hotspots, and the LLSVPs could probably play an important role for convection throughout the mantle and thermal structure and evolution of the earth. The LLSVPs have been considered to be heterogeneous in composition since the boundaries between the normal mantle are sharp. To investigate the details of the sharp LLSVP edge we measure ScS-S and SKS-S differential traveltimes in the hypocentral distance of about 60°-90° using Japanese and Chinese seismic networks. We used 25events for the Chinese network and 16 events for Japanese network that occurred in Tonga-Kermadec region and obtained 3750 event-station pairs of ScS-S and 1500 pairs of SKS-S differential travel times. We found anomalously large (more than 5 sec) ScS-S travel times accompanying normal SKS-S travel times, suggesting local strong slow region in the vicinity of the ScS bounce points (red circles in Figure 1). Such ScS bounce points locate to the northeast of New Guinea Island extending over 20 degrees in NE-SW direction. However below New Guinea Island, both ScS-S and SKS-S travel times are normal (green circles in Figure 1), indicating abrupt end of the local strong slow anomalies. We inverted the ScS-S and SKS-S differential traveltimes for lowermost mantle S-wave speed structure, assuming isotropic mantle. The result shows very strong slow anomalies of more than 5% at western edge of Pacific LLSVP that extend vertically not more than 200 km from the core mantle boundary.

Reading from an iPad or from a book in bed: the impact on human sleep. A randomized controlled crossover trial.

PubMed

Grønli, Janne; Byrkjedal, Ida Kristiansen; Bjorvatn, Bjørn; Nødtvedt, Øystein; Hamre, Børge; Pallesen, Ståle

2016-05-01

To objectively and subjectively compare whether reading a story for 30 min from an iPad or from a book in bed prior to sleep will differentially affect sleep. Sixteen students (12 females, mean age 25.1 ± 2.9 years) underwent ambulatory (sleeping in their own beds at home) polysomnographic (PSG) recordings in a counterbalanced crossover design consisting of three PSG nights (one adaptation night, two test nights) and two different reading materials: read from an iPad or from a book. Illumination was measured during reading and Karolinska Sleepiness Scale was completed prior to turning the light off. Sleep diaries were kept to assess subjective sleep parameters from day to day. Illumination was higher in the iPad condition compared to the book condition (58.3 ± 6.9 vs 26.7 ± 8.0 lux, p <0.001). Reading a story from an iPad decreased subjective sleepiness, delayed the EEG dynamics of slow wave activity by approximately 30 min, and reduced slow wave activity after sleep onset compared to reading from a book. No parameters of sleep state timing and sleep onset latency differed between the two reading conditions. Although there was no direct effect on time spent in different sleep states and self-reported sleep onset latency, the use of an iPad which emits blue enriched light impinges acutely on sleepiness and EEG characteristics of sleep pressure. Hence, the use of commercially available tablets may have consequences in terms of alertness, circadian physiology, and sleep. Published by Elsevier B.V.

[Reflex epilepsy evoked by decision making: report of a case (author's transl)].

PubMed

Mutani, R; Ganga, A; Agnetti, V

1980-01-01

A 17-year-old girl with a story of Gran Mal attacks occurring during lessons of mathematics or solving mathematical problems, was investigated with prolonged EEG recordings. During the sessions, relax periods were alternated with arithmetical or mathematical testing, with card or checkers games and solution of puzzles and crossword problems, and with different neuropsychological tests. EGG recordings were characterized by the appearance, on a normal background, of bilaterally synchronous and symmetrical spike-and-wave and polispike-and-wave discharges, associated with loss of consciousness. During relax their mean frequency was one/54 min., it doubled during execution of tests involved with nonsequential decision making, and was eight times as high (one/7 min.) during tests involving sequential decision making. Some tension, challenge and complexity of the performance were also important as precipitating factors. Their lack deprived sequential tests of their efficacy, while on the contrary their presence sometimes gave nonsequential tests full efficacy.

Disrupted hippocampal sharp-wave ripple-associated spike dynamics in a transgenic mouse model of dementia.

PubMed

Witton, Jonathan; Staniaszek, Lydia E; Bartsch, Ullrich; Randall, Andrew D; Jones, Matthew W; Brown, Jonathan T

2016-08-15

High frequency (100-250 Hz) neuronal oscillations in the hippocampus, known as sharp-wave ripples (SWRs), synchronise the firing behaviour of groups of neurons and play a key role in memory consolidation. Learning and memory are severely compromised in dementias such as Alzheimer's disease; however, the effects of dementia-related pathology on SWRs are unknown. The frequency and temporal structure of SWRs was disrupted in a transgenic mouse model of tauopathy (one of the major hallmarks of several dementias). Excitatory pyramidal neurons were more likely to fire action potentials in a phase-locked manner during SWRs in the mouse model of tauopathy; conversely, inhibitory interneurons were less likely to fire phase-locked spikes during SWRs. These findings indicate there is reduced inhibitory control of hippocampal network events and point to a novel mechanism which may underlie the cognitive impairments in this model of dementia. Neurons within the CA1 region of the hippocampus are co-activated during high frequency (100-250 Hz) sharp-wave ripple (SWR) activity in a manner that probably drives synaptic plasticity and promotes memory consolidation. In this study we have used a transgenic mouse model of dementia (rTg4510 mice), which overexpresses a mutant form of tau protein, to examine the effects of tauopathy on hippocampal SWRs and associated neuronal firing. Tetrodes were used to record simultaneous extracellular action potentials and local field potentials from the dorsal CA1 pyramidal cell layer of 7- to 8-month-old wild-type and rTg4510 mice at rest in their home cage. At this age point these mice exhibit neurofibrillary tangles, neurodegeneration and cognitive deficits. Epochs of sleep or quiet restfulness were characterised by minimal locomotor activity and a low theta/delta ratio in the local field potential power spectrum. SWRs detected off-line were significantly lower in amplitude and had an altered temporal structure in rTg4510 mice. Nevertheless, the average frequency profile and duration of the SWRs were relatively unaltered. Putative interneurons displayed significantly less temporal and phase locking to SWRs in rTg4510 mice, whilst putative pyramidal neurons showed increased temporal and phase locking to SWRs. These findings indicate there is reduced inhibitory control of hippocampal network events and point to a novel mechanism which may contribute to impairments in memory consolidation in this model of dementia. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

Electroencephalograph (EEG) study of brain bistable illusion

NASA Astrophysics Data System (ADS)

Meng, Qinglei; Hong, Elliot; Choa, Fow-Sen

2015-05-01

Bistable illusion reflects two different kinds of interpretations for a single image, which is currently known as a competition between two groups of antagonism of neurons. Recent research indicates that these two groups of antagonism of neurons express different comprehension, while one group is emitting a pulse, the other group will be restrained. On the other hand, when this inhibition mechanism becomes weaker, the other antagonism neurons group will take over the interpretation. Since attention plays key roles controlling cognition, is highly interesting to find the location and frequency band used by brain (with either top-down or bottom-up control) to reach deterministic visual perceptions. In our study, we used a 16-channel EEG system to record brain signals from subjects while conducting bistable illusion testing. An extra channel of the EEG system was used for temporal marking. The moment when subjects reach a perception switch, they click the channel and mark the time. The recorded data were presented in form of brain electrical activity map (BEAM) with different frequency bands for analysis. It was found that the visual cortex in the on the right side between parietal and occipital areas was controlling the switching of perception. In the periods with stable perception, we can constantly observe all the delta, theta, alpha and beta waves. While the period perception is switching, almost all theta, alpha, and beta waves were suppressed by delta waves. This result suggests that delta wave may control the processing of perception switching.

[Electroencephalography and epileptology in the 20th century].

PubMed

Karbowski, K

1995-12-05

In 1875, Caton was already able to detect cerebral electric currents during experimental studies in animals. In 1914, Cybulski and Jeleńska-Macieszyna reported on the increase of current-intensity during a focal motor epileptic seizure. In 1929 in Jena, Berger revolutionized the study of epilepsy with his paper on the human electroencephalogram 'Uber das Elektrenkephalogramm des Menschen'. His discovery and further publications as well as later works of numerous researchers, especially F. and E. Gibbs, Lennox, Penfield and Jasper, made it possible to distinguish different forms of 'little' epileptic seizures and to separate them from nonepileptic paroxysmal disorders. New epileptic syndromes could be singled out, as e.g. the symptomatic epilepsy of childhood with variable clinical manifestations of seizures and slow spike-wave complexes in the EEG (Lennox-Gastaut syndrome) or the benign partial epilepsy of childhood with centrotemporal EEG spikes. In these fields, as well as for the epileptic seizures in newborns and babies and for the differentiation between epileptic and nonepileptic twilight states in later stages of life, the EEG remains an indispensable tool in the CT and MRI era. It also contributes largely to the diagnosis of nonepileptic cerebral illness such as herpes simplex encephalitis, subacute sclerosing panencephalitis van Bogaert and Creutzfeldt-Jakob disease. Since the introduction of phenobarbital by Hauptmann in 1912, the palet of effective drugs against epilepsy, such as phenytoin, carbamazepine, valproate and benzodiazepines used for status-epilepticus treatment, became essentially larger. The value of newer substances (vigabatrin, progabide, gabapentin, lamotrigin) can't be estimated actually.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison between Scalp EEG and Behind-the-Ear EEG for Development of a Wearable Seizure Detection System for Patients with Focal Epilepsy

PubMed Central

Gu, Ying; Cleeren, Evy; Dan, Jonathan; Claes, Kasper; Hunyadi, Borbála

2017-01-01

A wearable electroencephalogram (EEG) device for continuous monitoring of patients suffering from epilepsy would provide valuable information for the management of the disease. Currently no EEG setup is small and unobtrusive enough to be used in daily life. Recording behind the ear could prove to be a solution to a wearable EEG setup. This article examines the feasibility of recording epileptic EEG from behind the ear. It is achieved by comparison with scalp EEG recordings. Traditional scalp EEG and behind-the-ear EEG were simultaneously acquired from 12 patients with temporal, parietal, or occipital lobe epilepsy. Behind-the-ear EEG consisted of cross-head channels and unilateral channels. The analysis on Electrooculography (EOG) artifacts resulting from eye blinking showed that EOG artifacts were absent on cross-head channels and had significantly small amplitudes on unilateral channels. Temporal waveform and frequency content during seizures from behind-the-ear EEG visually resembled that from scalp EEG. Further, coherence analysis confirmed that behind-the-ear EEG acquired meaningful epileptic discharges similarly to scalp EEG. Moreover, automatic seizure detection based on support vector machine (SVM) showed that comparable seizure detection performance can be achieved using these two recordings. With scalp EEG, detection had a median sensitivity of 100% and a false detection rate of 1.14 per hour, while, with behind-the-ear EEG, it had a median sensitivity of 94.5% and a false detection rate of 0.52 per hour. These findings demonstrate the feasibility of detecting seizures from EEG recordings behind the ear for patients with focal epilepsy. PMID:29295522

Altered slow wave activity in major depressive disorder with hypersomnia: a high density EEG pilot study

PubMed Central

Plante, David T.; Landsness, Eric C.; Peterson, Michael J.; Goldstein, Michael R.; Wanger, Tim; Guokas, Jeff J.; Tononi, Giulio; Benca, Ruth M.

2012-01-01

Hypersomnolence in major depressive disorder (MDD) plays an important role in the natural history of the disorder, but the basis of hypersomnia in MDD is poorly understood. Slow wave activity (SWA) has been associated with sleep homeostasis, as well as sleep restoration and maintenance, and may be altered in MDD. Therefore, we conducted a post-hoc study that utilized high density electroencephalography (hdEEG) to test the hypothesis that MDD subjects with hypersomnia (HYS+) would have decreased SWA relative to age and sex-matched MDD subjects without hypersomnia (HYS−) and healthy controls (n=7 for each group). After correcting for multiple comparisons using statistical non-parametric mapping, HYS+ subjects demonstrated significantly reduced parieto-occipital all-night SWA relative to HYS− subjects. Our results suggest hypersomnolence may be associated with topographic reductions in SWA in MDD. Further research using adequately powered prospective design is indicated to confirm these findings. PMID:22512951

The separate and combined effects of monoamine oxidase A inhibition and nicotine on resting state EEG.

PubMed

Smith, Dylan M; Fisher, Derek; Blier, Pierre; Ilivitsky, Vadim; Knott, Verner

2016-01-01

While nicotine is often associated with the neuropsychological effects of tobacco smoke, the robust monoamine oxidase (MAO) inhibition observed in chronic smokers is also likely to play a role. Electroencephalographically-indexed alterations in baseline neural oscillations by nicotine have previously been reported in both smokers and non-smokers, however, little is known about the effects of MAO inhibition in combination with nicotine on resting state EEG. In a sample of 24 healthy non-smoking males, the effects of 6 mg nicotine gum, as well as MAO-A inhibition via 75 mg moclobemide, were investigated in separate and combined conditions over four separate test sessions. Drug effects were observed in the alpha2, beta2, and theta band frequencies. Nicotine increased alpha2 power, and moclobemide decreased beta2 power. Theta power was decreased most robustly by the combination of both drugs. Therefore, this study demonstrated that the nicotinic and MAO inhibiting properties of tobacco may differentially influence fast-wave oscillations (alpha2 and beta2), while acting in synergy to influence theta oscillations. © The Author(s) 2015.

Epileptic spasms and early-onset photosensitive epilepsy in Patau syndrome: An EEG study.

PubMed

Spagnoli, Carlotta; Kugathasan, Umaiyal; Brittain, Helen; Boyd, Stewart G

2015-08-01

Patau syndrome, trisomy 13, is the third commonest autosomal trisomy. It is associated with a 25-50% prevalence of epilepsy, but detailed electroclinical descriptions are rare. The occurrence of early-onset photosensitivity has recently been reported in single patients. We collected electroclinical data on 8 infants (age range from 2 months to 3 years and 9 months, median: 17 months) with Patau syndrome referred for an EEG in our Clinical Neurophysiology Department between 1991 and 2011. All EEGs, case-notes, cytogenetic diagnosis and neuroimaging when available were reviewed; data on the occurrence of seizures, epileptiform discharges, photoparoxysmal response and their characteristics in terms of positive frequencies, latencies, grade and duration were noted and analysed. Two patients had been previously diagnosed with epilepsy (one with tonic spasms and one with multiple seizure types). We found 3 patients with photosensitive myoclonic epilepsy (37.5%), and one with non-photosensitive myoclonic epilepsy. We also recorded non-epileptic myoclonic jerks in one patient known to suffer from epileptic spasms. Among photosensitive patients we found self-limited, Waltz's grade 2-4, spike-wave/polyspike-wave discharges in low, medium and high frequency ranges in two patients and in the high frequency range in the third patient, with latencies and duration from less than 1s to a maximum of 9s. In our cohort of Patau syndrome patients, we found a high prevalence of spasms and photic-induced myoclonic jerks. Photosensitivity shows an unusual early age of onset. Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Non-REM sleep EEG power distribution in fatigue and sleepiness.

PubMed

Neu, Daniel; Mairesse, Olivier; Verbanck, Paul; Linkowski, Paul; Le Bon, Olivier

2014-04-01

The aim of this study is to contribute to the sleep-related differentiation between daytime fatigue and sleepiness. 135 subjects presenting with sleep apnea-hypopnea syndrome (SAHS, n=58) or chronic fatigue syndrome (CFS, n=52) with respective sleepiness or fatigue complaints and a control group (n=25) underwent polysomnography and psychometric assessments for fatigue, sleepiness, affective symptoms and perceived sleep quality. Sleep EEG spectral analysis for ultra slow, delta, theta, alpha, sigma and beta power bands was performed on frontal, central and occipital derivations. Patient groups presented with impaired subjective sleep quality and higher affective symptom intensity. CFS patients presented with highest fatigue and SAHS patients with highest sleepiness levels. All groups showed similar total sleep time. Subject groups mainly differed in sleep efficiency, wake after sleep onset, duration of light sleep (N1, N2) and slow wave sleep, as well as in sleep fragmentation and respiratory disturbance. Relative non-REM sleep power spectra distributions suggest a pattern of power exchange in higher frequency bands at the expense of central ultra slow power in CFS patients during all non-REM stages. In SAHS patients, however, we found an opposite pattern at occipital sites during N1 and N2. Slow wave activity presents as a crossroad of fatigue and sleepiness with, however, different spectral power band distributions during non-REM sleep. The homeostatic function of sleep might be compromised in CFS patients and could explain why, in contrast to sleepiness, fatigue does not resolve with sleep in these patients. The present findings thus contribute to the differentiation of both phenomena. Copyright © 2014 Elsevier Inc. All rights reserved.

Consciousness and Complexity during Unresponsiveness Induced by Propofol, Xenon, and Ketamine.

PubMed

Sarasso, Simone; Boly, Melanie; Napolitani, Martino; Gosseries, Olivia; Charland-Verville, Vanessa; Casarotto, Silvia; Rosanova, Mario; Casali, Adenauer Girardi; Brichant, Jean-Francois; Boveroux, Pierre; Rex, Steffen; Tononi, Giulio; Laureys, Steven; Massimini, Marcello

2015-12-07

A common endpoint of general anesthetics is behavioral unresponsiveness, which is commonly associated with loss of consciousness. However, subjects can become disconnected from the environment while still having conscious experiences, as demonstrated by sleep states associated with dreaming. Among anesthetics, ketamine is remarkable in that it induces profound unresponsiveness, but subjects often report "ketamine dreams" upon emergence from anesthesia. Here, we aimed at assessing consciousness during anesthesia with propofol, xenon, and ketamine, independent of behavioral responsiveness. To do so, in 18 healthy volunteers, we measured the complexity of the cortical response to transcranial magnetic stimulation (TMS)--an approach that has proven helpful in assessing objectively the level of consciousness irrespective of sensory processing and motor responses. In addition, upon emergence from anesthesia, we collected reports about conscious experiences during unresponsiveness. Both frontal and parietal TMS elicited a low-amplitude electroencephalographic (EEG) slow wave corresponding to a local pattern of cortical activation with low complexity during propofol anesthesia, a high-amplitude EEG slow wave corresponding to a global, stereotypical pattern of cortical activation with low complexity during xenon anesthesia, and a wakefulness-like, complex spatiotemporal activation pattern during ketamine anesthesia. Crucially, participants reported no conscious experience after emergence from propofol and xenon anesthesia, whereas after ketamine they reported long, vivid dreams unrelated to the external environment. These results are relevant because they suggest that brain complexity may be sensitive to the presence of disconnected consciousness in subjects who are considered unconscious based on behavioral responses. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hippocampal sharp wave-ripple: A cognitive biomarker for episodic memory and planning.

PubMed

Buzsáki, György

2015-10-01

Sharp wave ripples (SPW-Rs) represent the most synchronous population pattern in the mammalian brain. Their excitatory output affects a wide area of the cortex and several subcortical nuclei. SPW-Rs occur during "off-line" states of the brain, associated with consummatory behaviors and non-REM sleep, and are influenced by numerous neurotransmitters and neuromodulators. They arise from the excitatory recurrent system of the CA3 region and the SPW-induced excitation brings about a fast network oscillation (ripple) in CA1. The spike content of SPW-Rs is temporally and spatially coordinated by a consortium of interneurons to replay fragments of waking neuronal sequences in a compressed format. SPW-Rs assist in transferring this compressed hippocampal representation to distributed circuits to support memory consolidation; selective disruption of SPW-Rs interferes with memory. Recently acquired and pre-existing information are combined during SPW-R replay to influence decisions, plan actions and, potentially, allow for creative thoughts. In addition to the widely studied contribution to memory, SPW-Rs may also affect endocrine function via activation of hypothalamic circuits. Alteration of the physiological mechanisms supporting SPW-Rs leads to their pathological conversion, "p-ripples," which are a marker of epileptogenic tissue and can be observed in rodent models of schizophrenia and Alzheimer's Disease. Mechanisms for SPW-R genesis and function are discussed in this review. © 2015 The Authors Hippocampus Published by Wiley Periodicals, Inc.

The Accuracy, Night-to-Night Variability, and Stability of Frontopolar Sleep Electroencephalography Biomarkers

PubMed Central

Levendowski, Daniel J.; Ferini-Strambi, Luigi; Gamaldo, Charlene; Cetel, Mindy; Rosenberg, Robert; Westbrook, Philip R.

2017-01-01

Study Objectives: To assess the validity of sleep architecture and sleep continuity biomarkers obtained from a portable, multichannel forehead electroencephalography (EEG) recorder. Methods: Forty-seven subjects simultaneously underwent polysomnography (PSG) while wearing a multichannel frontopolar EEG recording device (Sleep Profiler). The PSG recordings independently staged by 5 registered polysomnographic technologists were compared for agreement with the autoscored sleep EEG before and after expert review. To assess the night-to-night variability and first night bias, 2 nights of self-applied, in-home EEG recordings obtained from a clinical cohort of 63 patients were used (41% with a diagnosis of insomnia/depression, 35% with insomnia/obstructive sleep apnea, and 17.5% with all three). The between-night stability of abnormal sleep biomarkers was determined by comparing each night's data to normative reference values. Results: The mean overall interscorer agreements between the 5 technologists were 75.9%, and the mean kappa score was 0.70. After visual review, the mean kappa score between the autostaging and five raters was 0.67, and staging agreed with a majority of scorers in at least 80% of the epochs for all stages except stage N1. Sleep spindles, autonomic activation, and stage N3 exhibited the least between-night variability (P < .0001) and strongest between-night stability. Antihypertensive medications were found to have a significant effect on sleep quality biomarkers (P < .02). Conclusions: A strong agreement was observed between the automated sleep staging and human-scored PSG. One night's recording appeared sufficient to characterize abnormal slow wave sleep, sleep spindle activity, and heart rate variability in patients, but a 2-night average improved the assessment of all other sleep biomarkers. Commentary: Two commentaries on this article appear in this issue on pages 771 and 773. Citation: Levendowski DJ, Ferini-Strambi L, Gamaldo C, Cetel M, Rosenberg R, Westbrook PR. The accuracy, night-to-night variability, and stability of frontopolar sleep electroencephalography biomarkers. J Clin Sleep Med. 2017;13(6):791–803. PMID:28454598

Brain wave correlates of attentional states: Event related potentials and quantitative EEG analysis during performance of cognitive and perceptual tasks

NASA Technical Reports Server (NTRS)

Freeman, Frederick G.

1993-01-01

The increased use of automation in the cockpits of commercial planes has dramatically decreased the workload requirements of pilots, enabling them to function more efficiently and with a higher degree of safety. Unfortunately, advances in technology have led to an unexpected problem: the decreased demands on pilots have increased the probability of inducing 'hazardous states of awareness.' A hazardous state of awareness is defined as a decreased level of alertness or arousal which makes an individual less capable of reacting to unique or emergency types of situations. These states tend to be induced when an individual is not actively processing information. Under such conditions a person is likely to let his/her mind wander, either to internal states or to irrelevant external conditions. As a result, they are less capable of reacting quickly to emergency situations. Since emergencies are relatively rare, and since the high automated cockpit requires progressively decreasing levels of engagement, the probability of being seduced into a lowered state of awareness is increasing. This further decreases the readiness of the pilot to react to unique circumstances such as system failures. The HEM Lab at NASA-Langley Research Center has been studying how these states of awareness are induced and what the physiological correlates of these different states are. Specifically, they have been interested in studying electroencephalographic (EEG) measures of different states of alertness to determine if such states can be identified and, hopefully, avoided. The project worked on this summer involved analyzing the EEG and the event related potentials (ERP) data collected while subjects performed under two conditions. Each condition required subjects to perform a relatively boring vigilance task. The purpose of using these tasks was to induce a decreased state of awareness while still requiring the subject to process information. Each task involved identifying an infrequently presented target stimulus. In addition to the task requirements, irrelevant tones were presented in the background. Research has shown that even though these stimuli are not attended, ERP's to them can still be elicited. The amplitude of the ERP waves has been shown to change as a function of a person's level of alertness. ERP's were also collected and analyzed for the target stimuli for each task. Brain maps were produced based on the ERP voltages for the different stimuli. In addition to the ERP's, a quantitative EEG (QEEG) was performed on the data using a fast Fourier technique to produce a power spectral analysis of the EEG. This analysis was conducted on the continuous EEG while the subjects were performing the tasks. Finally, a QEEG was performed on periods during the task when subjects indicated that they were in an altered state of awareness. During the tasks, subjects were asked to indicate by pressing a button when they realized their level of task awareness had changed. EEG epochs were collected for times just before and just after subjects made this reponse. The purpose of this final analysis was to determine whether or not subjective indices of level of awareness could be correlated with different patterns of EEG.

New mechanism of surface polariton resonance at an isolated interface between transparent dielectric media (non-Tamm quasistationary surface polariton states)

NASA Astrophysics Data System (ADS)

Tarasenko, S. V.; Shavrov, V. G.

2017-07-01

A pseudochiral mechanism of the formation of non-Tamm quasistationary surface polariton states, as well as surface polariton waves inside the light cone, has been proposed for an isolated interface between spatially uniform transparent dielectric media. The resonance excitation of these states by a quasimonochromatic plane wave incident from vacuum results in a sharp change in the group delay time of the reflected pulse. The effect is enhanced in the presence of an electromagnetic metasurface.

Time-Frequency Analysis of Boundary-Layer Instabilites Generated by Freestream Laser Perturbations

NASA Technical Reports Server (NTRS)

Chou, Amanda; Schneider, Steven P.

2015-01-01

A controlled disturbance is generated in the freestream of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT) by focusing a high-powered Nd:YAG laser to create a laser-induced breakdown plasma. The plasma then cools, creating a freestream thermal disturbance that can be used to study receptivity. The freestream disturbance convects down-stream in the Mach-6 wind tunnel to interact with a flared cone model. The adverse pressure gradient created by the flare of the model is capable of generating second-mode instability waves that grow large and become nonlinear before experiencing natural transition in quiet flow. The freestream laser perturbation generates a wave packet in the boundary layer at the same frequency as the natural second mode, complicating time-independent analyses of the effect of the laser perturbation. The data show that the laser perturbation creates an instability wave packet that is larger than the natural waves on the sharp flared cone. The wave packet is still difficult to distinguish from the natural instabilities on the blunt flared cone.

Stability of standing wave for the fractional nonlinear Schrödinger equation

NASA Astrophysics Data System (ADS)

Peng, Congming; Shi, Qihong

2018-01-01

In this paper, we study the stability and instability of standing waves for the fractional nonlinear Schrödinger equation i∂tu = (-Δ)su - |u|2σu, where (t ,x ) ∈R × RN, 1/2