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

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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.

Artificial theta stimulation impairs encoding of contextual fear memory.

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Arto Lipponen

Full Text Available Several experiments have demonstrated an intimate relationship between hippocampal theta rhythm (4-12 Hz and memory. Lesioning the medial septum or fimbria-fornix, a fiber track connecting the hippocampus and the medial septum, abolishes the theta rhythm and results in a severe impairment in declarative memory. To assess whether there is a causal relationship between hippocampal theta and memory formation we investigated whether restoration of hippocampal theta by electrical stimulation during the encoding phase also restores fimbria-fornix lesion induced memory deficit in rats in the fear conditioning paradigm. Male Wistar rats underwent sham or fimbria-fornix lesion operation. Stimulation electrodes were implanted in the ventral hippocampal commissure and recording electrodes in the septal hippocampus. Artificial theta stimulation of 8 Hz was delivered during 3-min free exploration of the test cage in half of the rats before aversive conditioning with three foot shocks during 2 min. Memory was assessed by total freezing time in the same environment 24 h and 28 h after fear conditioning, and in an intervening test session in a different context. As expected, fimbria-fornix lesion impaired fear memory and dramatically attenuated hippocampal theta power. Artificial theta stimulation produced continuous theta oscillations that were almost similar to endogenous theta rhythm in amplitude and frequency. However, contrary to our predictions, artificial theta stimulation impaired conditioned fear response in both sham and fimbria-fornix lesioned animals. These data suggest that restoration of theta oscillation per se is not sufficient to support memory encoding after fimbria-fornix lesion and that universal theta oscillation in the hippocampus with a fixed frequency may actually impair memory.

Efficient alpha particle detection by CR-39 applying 50 Hz-HV electrochemical etching method

International Nuclear Information System (INIS)

Sohrabi, M.; Soltani, Z.

2016-01-01

Alpha particles can be detected by CR-39 by applying either chemical etching (CE), electrochemical etching (ECE), or combined pre-etching and ECE usually through a multi-step HF-HV ECE process at temperatures much higher than room temperature. By applying pre-etching, characteristics responses of fast-neutron-induced recoil tracks in CR-39 by HF-HV ECE versus KOH normality (N) have shown two high-sensitivity peaks around 5–6 and 15–16 N and a large-diameter peak with a minimum sensitivity around 10–11 N at 25°C. On the other hand, 50 Hz-HV ECE method recently advanced in our laboratory detects alpha particles with high efficiency and broad registration energy range with small ECE tracks in polycarbonate (PC) detectors. By taking advantage of the CR-39 sensitivity to alpha particles, efficacy of 50 Hz-HV ECE method and CR-39 exotic responses under different KOH normalities, detection characteristics of 0.8 MeV alpha particle tracks were studied in 500 μm CR-39 for different fluences, ECE duration and KOH normality. Alpha registration efficiency increased as ECE duration increased to 90 ± 2% after 6–8 h beyond which plateaus are reached. Alpha track density versus fluence is linear up to 10 6  tracks cm −2 . The efficiency and mean track diameter versus alpha fluence up to 10 6  alphas cm −2 decrease as the fluence increases. Background track density and minimum detection limit are linear functions of ECE duration and increase as normality increases. The CR-39 processed for the first time in this study by 50 Hz-HV ECE method proved to provide a simple, efficient and practical alpha detection method at room temperature. - Highlights: • Alpha particles of 0.8 MeV were detected in CR-39 by 50 Hz-HV ECE method. • Efficiency/track diameter was studied vs fluence and time for 3 KOH normality. • Background track density and minimum detection limit vs duration were studied. • A new simple, efficient and low-cost alpha detection method

No-carrier-added (NCA) synthesis of 6-[{sup 18}F]fluoro-L-DOPA using 3,5,6,7,8,8a-hexahydro-7,7,8a-trimethyl-[6S-(6{alpha}, 8{alpha}, 8{alpha}{beta})]-6,8-methano-2H-1,4-benzoxazin-2-one

Energy Technology Data Exchange (ETDEWEB)

Horti, A. [Yale Univ., New Haven, CT (United States). School of Medicine]|[Yale Univ., West Haven, CT (United States). PET Center; Redmond, D.E. Jr. [Yale Univ., New Haven, CT (United States). School of Medicine; Soufer, R. [Yale Univ., West Haven, CT (United States). PET Center

1995-12-31

3,5,6,7,8,8a-Hexahydro-7,7,8a-trimethyl-[6S-(6{alpha},8{alpha} , 8{alpha}{beta})]-6,8-methano-2H-1,4-benzoxazino-2-one (2) was investigated as chiral auxiliary for asymmetric NCA nucleophilic synthesis of 6-[{sup 18}F]Fluoro-L-DOPA. Direct condensation of 3,4-dimethoxy-2-[{sup 18}F]fluorobenzaldehyde (1a) or 6-[{sup 18}F]fluoro-piperonal (1b) in the presence of NaH with 2 gave the corresponding [{sup 18}F]-3-[(2-fluorophenyl)methylene]-3,5,6,7,8,8a-hexahydro-7,7,8 a-trimethyl-[6S-(3Z,3{alpha},6{alpha},8{alpha},8{alpha}{beta})]-6, 8-methano-2H-1,4-benzoxazin-2-one derivative 3a or 3b as a single stereoisomer. L-Selectride promoted hydrogenation of the olefinic double bond of these derivatives, in presence of tertbutyl alcohol, afforded the corresponding [{sup 18}F]-3-[(2-fluorophenyl) methyl]-3,5,6,7,8,8a-hexahydro-7,7,8a-trimethyl-[3S-(3{alpha}, 6{alpha}, 8{alpha}8{alpha}{beta})]-6,8-methano-2H-1,4-benzoxazin-2-one derivatives (4a,b) without affecting the orientation of diasterofacial discrimination. Deprotection of the derivatives 4a,b yielded 6-[{sup 18}F]fluoro-L-DOPA (e.e. >90%, 3% radiochemical yield (EOB), total synthesis time 125 min, specific activity >2000 mCi/{mu}mol). Direct deprotection/reduction of the compounds 3a,b provides the enantiomeric mixture of 6-[{sup 18}F]fluoro-D,L-DOPA (10-12% radiochemical yield) and, after chiral separation, 6-[{sup 18}F]fluoro-L-DOPA (e.e. 98%, 4-5% radiochemical yield). (author).

Predictability of depression severity based on posterior alpha oscillations.

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Jiang, H; Popov, T; Jylänki, P; Bi, K; Yao, Z; Lu, Q; Jensen, O; van Gerven, M A J

2016-04-01

We aimed to integrate neural data and an advanced machine learning technique to predict individual major depressive disorder (MDD) patient severity. MEG data was acquired from 22 MDD patients and 22 healthy controls (HC) resting awake with eyes closed. Individual power spectra were calculated by a Fourier transform. Sources were reconstructed via beamforming technique. Bayesian linear regression was applied to predict depression severity based on the spatial distribution of oscillatory power. In MDD patients, decreased theta (4-8 Hz) and alpha (8-14 Hz) power was observed in fronto-central and posterior areas respectively, whereas increased beta (14-30 Hz) power was observed in fronto-central regions. In particular, posterior alpha power was negatively related to depression severity. The Bayesian linear regression model showed significant depression severity prediction performance based on the spatial distribution of both alpha (r=0.68, p=0.0005) and beta power (r=0.56, p=0.007) respectively. Our findings point to a specific alteration of oscillatory brain activity in MDD patients during rest as characterized from MEG data in terms of spectral and spatial distribution. The proposed model yielded a quantitative and objective estimation for the depression severity, which in turn has a potential for diagnosis and monitoring of the recovery process. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

A theory of alpha/theta neurofeedback, creative performance enhancement, long distance functional connectivity and psychological integration.

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Gruzelier, John

2009-02-01

Professionally significant enhancement of music and dance performance and mood has followed training with an EEG-neurofeedback protocol which increases the ratio of theta to alpha waves using auditory feedback with eyes closed. While originally the protocol was designed to induce hypnogogia, a state historically associated with creativity, the outcome was psychological integration, while subsequent applications focusing on raising the theta-alpha ratio, reduced depression and anxiety in alcoholism and resolved post traumatic stress syndrome (PTSD). In optimal performance studies we confirmed associations with creativity in musical performance, but effects also included technique and communication. We extended efficacy to dance and social anxiety. Diversity of outcome has a counterpart in wide ranging associations between theta oscillations and behaviour in cognitive and affective neuroscience: in animals with sensory-motor activity in exploration, effort, working memory, learning, retention and REM sleep; in man with meditative concentration, reduced anxiety and sympathetic autonomic activation, as well as task demands in virtual spatial navigation, focussed and sustained attention, working and recognition memory, and having implications for synaptic plasticity and long term potentiation. Neuroanatomical circuitry involves the ascending mescencephalic-cortical arousal system, and limbic circuits subserving cognitive as well as affective/motivational functions. Working memory and meditative bliss, representing cognitive and affective domains, respectively, involve coupling between frontal and posterior cortices, exemplify a role for theta and alpha waves in mediating the interaction between distal and widely distributed connections. It is posited that this mediation in part underpins the integrational attributes of alpha-theta training in optimal performance and psychotherapy, creative associations in hypnogogia, and enhancement of technical, communication and

Dynamical stability of the alpha and theta phases of alumina

DEFF Research Database (Denmark)

Lodziana, Zbigniew; Parlinski, K.

2003-01-01

Using density functional calculations the phonon dispersion relations, phonon density of states, and free energy of theta and alpha phases of alumina are investigated. The temperature dependence of the free energy indicates that entropy contributes to the destabilization of the alpha phase...... cations in alumina, and suggest that some other than entropic mechanism exists, which stabilizes transition aluminas up to 1400 K. The present calculations go beyond the ground state energy calculations [C. Wolverton and K.C. Hass, Phys. Rev. B 63, 24102 (2001)], and give an additional understanding...... of the stability of transition alumina at finite temperatures....

A Randomized Trial of Comparing the Efficacy of Two Neurofeedback Protocols for Treatment of Clinical and Cognitive Symptoms of ADHD: Theta Suppression/Beta Enhancement and Theta Suppression/Alpha Enhancement

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Arash Mohagheghi

2017-01-01

Full Text Available Introduction. Neurofeedback (NF is an adjuvant or alternative therapy for children with Attention Deficit Hyperactivity Disorder (ADHD. This study intended to compare the efficacy of two different NF protocols on clinical and cognitive symptoms of ADHD. Materials and Methods. In this clinical trial, sixty children with ADHD aged 7 to 10 years old were randomly grouped to receive two different NF treatments (theta suppression/beta enhancement protocol and theta suppression/alpha enhancement protocol. Clinical and cognitive assessments were conducted prior to and following the treatment and also after an eight-week follow-up. Results. Both protocols alleviated the symptoms of ADHD in general (p<0.001, hyperactivity (p<0.001, inattention (p<0.001, and omission errors (p<0.001; however, they did not affect the oppositional and impulsive scales nor commission errors. These effects were maintained after an eight-week intervention-free period. The only significant difference between the two NF protocols was that high-frequency alpha enhancement protocol performed better in suppressing omission errors (p<0.001. Conclusion. The two NF protocols with theta suppression/beta enhancement and theta suppression/alpha enhancement have considerable and comparable effect on clinical symptoms of ADHD. Alpha enhancement protocol was more effective in suppressing omission errors.

Association of single nucleotide polymorphisms in a glutamate receptor gene (GRM8) with theta power of event-related oscillations and alcohol dependence.

Science.gov (United States)

Chen, Andrew C H; Tang, Yongqiang; Rangaswamy, Madhavi; Wang, Jen C; Almasy, Laura; Foroud, Tatiana; Edenberg, Howard J; Hesselbrock, Victor; Nurnberger, John; Kuperman, Samuel; O'Connor, Sean J; Schuckit, Marc A; Bauer, Lance O; Tischfield, Jay; Rice, John P; Bierut, Laura; Goate, Alison; Porjesz, Bernice

2009-04-05

Evidence suggests the P3 amplitude of the event-related potential and its underlying superimposed event-related oscillations (EROs), primarily in the theta (4-5 Hz) and delta (1-3 Hz) frequencies, as endophenotypes for the risk of alcoholism and other disinhibitory disorders. Major neurochemical substrates contributing to theta and delta rhythms and P3 involve strong GABAergic, cholinergic and glutamatergic system interactions. The aim of this study was to test the potential associations between single nucleotide polymorphisms (SNPs) in glutamate receptor genes and ERO quantitative traits. GRM8 was selected because it maps at chromosome 7q31.3-q32.1 under the peak region where we previously identified significant linkage (peak LOD = 3.5) using a genome-wide linkage scan of the same phenotype (event-related theta band for the target visual stimuli). Neural activities recorded from scalp electrodes during a visual oddball task in which rare target elicited P3s were analyzed in a subset of the Collaborative Study on the Genetics of Alcoholism (COGA) sample comprising 1,049 Caucasian subjects from 209 families (with 472 DSM-IV alcohol dependent individuals). The family-based association test (FBAT) detected significant association (P power to target visual stimuli, and also with alcohol dependence, even after correction for multiple comparisons by false discovery rate (FDR). Our results suggest that variation in GRM8 may be involved in modulating event-related theta oscillations during information processing and also in vulnerability to alcoholism. These findings underscore the utility of electrophysiology and the endophenotype approach in the genetic study of psychiatric disorders. (c) 2008 Wiley-Liss, Inc.

Theta power is reduced in healthy cognitive aging.

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Cummins, Tarrant D R; Finnigan, Simon

2007-10-01

The effects of healthy cognitive aging on electroencephalographic (EEG) theta (4.9-6.8 Hz) power were examined during performance of a modified Sternberg, S., 1966. High-speed scanning in human memory. Science 153, 652-654.) word recognition task. In a sample of fourteen young (mean age 21.9 years, range=18-27) and fourteen older (mean age 68.4 years, range=60-80) participants, theta power was found to be significantly lower in older adults during both the retention and recognition intervals. This theta power difference was greatest at the fronto-central midline electrode and occurred in parallel with a small, non-significant decrease in recognition accuracy in the older sample. A significant decrease in older adults' mean theta power was also observed in resting EEG, however, it was of substantially smaller magnitude than the task-related theta difference. It is proposed that a neurophysiological measure(s), such as task-specific frontal midline theta (fmtheta) power, may be a more sensitive marker of cognitive aging than task performance measures. Furthermore, as recent research indicates that fmtheta is generated primarily in the anterior cingulate cortex, the current findings support evidence that the function of brain networks incorporating this structure may be affected in cognitive aging.

Distinct slow and fast cortical theta dynamics in episodic memory retrieval.

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Pastötter, Bernhard; Bäuml, Karl-Heinz T

2014-07-01

Brain oscillations in the theta frequency band (3-8 Hz) have been shown to be critically involved in human episodic memory retrieval. In prior work, both positive and negative relationships between cortical theta power and retrieval success have been reported. This study examined the hypothesis that slow and fast cortical theta oscillations at the edges of the traditional theta frequency band are differentially related to retrieval success. Scalp EEG was recorded in healthy human participants as they performed a cued-recall episodic memory task. Slow (~3 Hz) and fast (~7 Hz) theta oscillations at retrieval were examined as a function of whether an item was recalled or not and as a function of the items' output position at test. Recall success typically declines with output position, due to increases in interference level. The results showed that slow theta power was positively related but fast theta power was negatively related to retrieval success. Concurrent positive and negative episodic memory effects for slow and fast theta oscillations were dissociable in time and space, showing different time courses and different spatial locations on the scalp. Moreover, fast theta power increased from early to late output positions, whereas slow theta power was unaffected by items' output position. Together with prior work, the results suggest that slow and fast theta oscillations have distinct functional roles in episodic memory retrieval, with slow theta oscillations being related to processes of recollection and conscious awareness, and fast theta oscillations being linked to processes of interference and interference resolution. Copyright © 2014 Elsevier Inc. All rights reserved.

Using theta and alpha band power to assess cognitive workload in multitasking environments.

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Puma, Sébastien; Matton, Nadine; Paubel, Pierre-V; Raufaste, Éric; El-Yagoubi, Radouane

2018-01-01

Cognitive workload is of central importance in the fields of human factors and ergonomics. A reliable measurement of cognitive workload could allow for improvements in human machine interface designs and increase safety in several domains. At present, numerous studies have used electroencephalography (EEG) to assess cognitive workload, reporting the rise in cognitive workload to be associated with increases in theta band power and decreases in alpha band power. However, results have been inconsistent with some failing to reach the required level of significance. We hypothesized that the lack of consistency could be related to individual differences in task performance and/or to the small sample sizes in most EEG studies. In the present study we used EEG to assess the increase in cognitive workload occurring in a multitasking environment while taking into account differences in performance. Twenty participants completed a task commonly used in airline pilot recruitment, which included an increasing number of concurrent sub-tasks to be processed from one to four. Subjective ratings, performances scores, pupil size and EEG signals were recorded. Results showed that increases in EEG alpha and theta band power reflected increases in the involvement of cognitive resources for the completion of one to three subtasks in a multitasking environment. These values reached a ceiling when performances dropped. Consistent differences in levels of alpha and theta band power were associated to levels of task performance: highest performance was related to lowest band power. Copyright © 2017 Elsevier B.V. All rights reserved.

Individual Alpha Peak Frequency Predicts 10 Hz Flicker Effects on Selective Attention.

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Gulbinaite, Rasa; van Viegen, Tara; Wieling, Martijn; Cohen, Michael X; VanRullen, Rufin

2017-10-18

Rhythmic visual stimulation ("flicker") is primarily used to "tag" processing of low-level visual and high-level cognitive phenomena. However, preliminary evidence suggests that flicker may also entrain endogenous brain oscillations, thereby modulating cognitive processes supported by those brain rhythms. Here we tested the interaction between 10 Hz flicker and endogenous alpha-band (∼10 Hz) oscillations during a selective visuospatial attention task. We recorded EEG from human participants (both genders) while they performed a modified Eriksen flanker task in which distractors and targets flickered within (10 Hz) or outside (7.5 or 15 Hz) the alpha band. By using a combination of EEG source separation, time-frequency, and single-trial linear mixed-effects modeling, we demonstrate that 10 Hz flicker interfered with stimulus processing more on incongruent than congruent trials (high vs low selective attention demands). Crucially, the effect of 10 Hz flicker on task performance was predicted by the distance between 10 Hz and individual alpha peak frequency (estimated during the task). Finally, the flicker effect on task performance was more strongly predicted by EEG flicker responses during stimulus processing than during preparation for the upcoming stimulus, suggesting that 10 Hz flicker interfered more with reactive than proactive selective attention. These findings are consistent with our hypothesis that visual flicker entrained endogenous alpha-band networks, which in turn impaired task performance. Our findings also provide novel evidence for frequency-dependent exogenous modulation of cognition that is determined by the correspondence between the exogenous flicker frequency and the endogenous brain rhythms. SIGNIFICANCE STATEMENT Here we provide novel evidence that the interaction between exogenous rhythmic visual stimulation and endogenous brain rhythms can have frequency-specific behavioral effects. We show that alpha-band (10 Hz) flicker impairs stimulus

Theta coupling between V4 and prefrontal cortex predicts visual short-term memory performance.

Science.gov (United States)

Liebe, Stefanie; Hoerzer, Gregor M; Logothetis, Nikos K; Rainer, Gregor

2012-01-29

Short-term memory requires communication between multiple brain regions that collectively mediate the encoding and maintenance of sensory information. It has been suggested that oscillatory synchronization underlies intercortical communication. Yet, whether and how distant cortical areas cooperate during visual memory remains elusive. We examined neural interactions between visual area V4 and the lateral prefrontal cortex using simultaneous local field potential (LFP) recordings and single-unit activity (SUA) in monkeys performing a visual short-term memory task. During the memory period, we observed enhanced between-area phase synchronization in theta frequencies (3-9 Hz) of LFPs together with elevated phase locking of SUA to theta oscillations across regions. In addition, we found that the strength of intercortical locking was predictive of the animals' behavioral performance. This suggests that theta-band synchronization coordinates action potential communication between V4 and prefrontal cortex that may contribute to the maintenance of visual short-term memories.

Pre-stimulus thalamic theta power predicts human memory formation.

Science.gov (United States)

Sweeney-Reed, Catherine M; Zaehle, Tino; Voges, Jürgen; Schmitt, Friedhelm C; Buentjen, Lars; Kopitzki, Klaus; Richardson-Klavehn, Alan; Hinrichs, Hermann; Heinze, Hans-Jochen; Knight, Robert T; Rugg, Michael D

2016-09-01

Pre-stimulus theta (4-8Hz) power in the hippocampus and neocortex predicts whether a memory for a subsequent event will be formed. Anatomical studies reveal thalamus-hippocampal connectivity, and lesion, neuroimaging, and electrophysiological studies show that memory processing involves the dorsomedial (DMTN) and anterior thalamic nuclei (ATN). The small size and deep location of these nuclei have limited real-time study of their activity, however, and it is unknown whether pre-stimulus theta power predictive of successful memory formation is also found in these subcortical structures. We recorded human electrophysiological data from the DMTN and ATN of 7 patients receiving deep brain stimulation for refractory epilepsy. We found that greater pre-stimulus theta power in the right DMTN was associated with successful memory encoding, predicting both behavioral outcome and post-stimulus correlates of successful memory formation. In particular, significant correlations were observed between right DMTN theta power and both frontal theta and right ATN gamma (32-50Hz) phase alignment, and frontal-ATN theta-gamma cross-frequency coupling. We draw the following primary conclusions. Our results provide direct electrophysiological evidence in humans of a role for the DMTN as well as the ATN in memory formation. Furthermore, prediction of subsequent memory performance by pre-stimulus thalamic oscillations provides evidence that post-stimulus differences in thalamic activity that index successful and unsuccessful encoding reflect brain processes specifically underpinning memory formation. Finally, the findings broaden the understanding of brain states that facilitate memory encoding to include subcortical as well as cortical structures. Copyright © 2016 Elsevier Inc. All rights reserved.

Corticostriatal field potentials are modulated at delta and theta frequencies during interval-timing task in rodents

Directory of Open Access Journals (Sweden)

Eric B Emmons

2016-04-01

Full Text Available Organizing movements in time is a critical and highly conserved feature of mammalian behavior. Temporal control of action requires corticostriatal networks. We investigate these networks in rodents using a two-interval timing task while recording local field potentials in medial frontal cortex or dorsomedial striatum. Consistent with prior work, we found cue-triggered delta (1-4 Hz and theta activity (4-8 Hz primarily in rodent medial frontal cortex. We observed delta activity across temporal intervals in medial frontal cortex and dorsomedial striatum. Rewarded responses were associated with increased delta activity in medial frontal cortex. Activity in theta bands in medial frontal cortex and delta bands in the striatum was linked with the timing of responses. These data suggest both delta and theta activity in frontostriatal networks are modulated during interval timing and that activity in these bands may be involved in the temporal control of action.

Fronto-parietal and fronto-temporal theta phase synchronization for visual and auditory-verbal working memory

OpenAIRE

Masahiro eKawasaki; Masahiro eKawasaki; Masahiro eKawasaki; Keiichi eKitajo; Keiichi eKitajo; Yoko eYamaguchi

2014-01-01

In humans, theta phase (4–8 Hz) synchronization observed on electroencephalography (EEG) plays an important role in the manipulation of mental representations during working memory (WM) tasks; fronto-temporal synchronization is involved in auditory-verbal WM tasks and fronto-parietal synchronization is involved in visual WM tasks. However, whether or not theta phase synchronization is able to select the to-be-manipulated modalities is uncertain. To address the issue, we recorded EEG data from...

Classification of single normal and Alzheimer’s disease individuals from cortical sources of resting state EEG rhythms

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Claudio eBabiloni

2016-02-01

Full Text Available Previous studies have shown abnormal power and functional connectivity of resting state electroencephalographic (EEG rhythms in groups of Alzheimer’s disease (AD compared to healthy elderly (Nold subjects. Here we tested the best classification rate of 120 AD patients and 100 matched Nold subjects using EEG markers based on cortical sources of power and functional connectivity of these rhythms. EEG data were recorded during resting state eyes-closed condition. Exact low-resolution brain electromagnetic tomography (eLORETA estimated the power and functional connectivity of cortical sources in frontal, central, parietal, occipital, temporal, and limbic regions. Delta (2-4 Hz, theta (4-8 Hz, alpha 1 (8-10.5 Hz, alpha 2 (10.5-13 Hz, beta 1 (13-20 Hz, beta 2 (20-30 Hz, and gamma (30-40 Hz were the frequency bands of interest. The classification rates of interest were those with an area under the receiver operating characteristic curve (AUROC higher than 0.7 as a threshold for a moderate classification rate (i.e. 70%. Results showed that the following EEG markers overcame this threshold: (i central, parietal, occipital, temporal, and limbic delta/alpha 1 current density; (ii central, parietal, occipital temporal, and limbic delta/alpha 2 current density; (iii frontal theta/alpha 1 current density; (iv occipital delta/alpha 1 inter-hemispherical connectivity; (v occipital-temporal theta/alpha 1 right and left intra-hemispherical connectivity; and (vi parietal-limbic alpha 1 right intra-hemispherical connectivity. Occipital delta/alpha 1 current density showed the best classification rate (sensitivity of 73.3%, specificity of 78%, accuracy of 75.5%, and AUROC of 82%. These results suggest that EEG source markers can classify Nold and AD individuals with a moderate classification rate higher than 80%.

Impaired theta-gamma coupling during working memory performance in schizophrenia.

Science.gov (United States)

Barr, Mera S; Rajji, Tarek K; Zomorrodi, Reza; Radhu, Natasha; George, Tony P; Blumberger, Daniel M; Daskalakis, Zafiris J

2017-11-01

Working memory deficits represent a core feature of schizophrenia. These deficits have been associated with dysfunctional dorsolateral prefrontal cortex (DLPFC) cortical oscillations. Theta-gamma coupling describes the modulation of gamma oscillations by theta phasic activity that has been directly associated with the ordering of information during working memory performance. Evaluating theta-gamma coupling may provide greater insight into the neural mechanisms mediating working memory deficits in this disorder. Thirty-eight patients diagnosed with schizophrenia or schizoaffective disorder and 38 healthy controls performed the verbal N-Back task administered at 4 levels, while EEG was recorded. Theta (4-7Hz)-gamma (30-50Hz) coupling was calculated for target and non-target correct trials for each working memory load. The relationship between theta-gamma coupling and accuracy was determined. Theta-gamma coupling was significantly and selectively impaired during correct responses to target letters among schizophrenia patients compared to healthy controls. A significant and positive relationship was found between theta-gamma coupling and 3-Back accuracy in controls, while this relationship was not observed in patients. These findings suggest that impaired theta-gamma coupling contribute to working memory dysfunction in schizophrenia. Future work is needed to evaluate the predictive utility of theta-gamma coupling as a neurophysiological marker for functional outcomes in this disorder. Copyright © 2017. Published by Elsevier B.V.

Correlation between quantitative EEG and cerebral blood flow and oxygen metabolism in patients with dementia of Alzheimer type

International Nuclear Information System (INIS)

Kudoh, Masako; Takahashi, Satoshi; Yonezawa, Hisashi

1997-01-01

Quantitative scalp EEG and cerebral blood flow (CBF) and oxygen metabolism (CMRO 2 ) measured by the steady-state 15 O technique and positron emission tomography were studied in 19 patients with mild to moderate dementia of Alzheimer type (DAT) and age-matched controls (EEG=19, PET=6). Scalp electrodes were placed according to the international 10-20 method except for Cz, T3, and T4. To evaluate the relative changes in power for each frequency band between the two groups, the percentage power fraction (percentage power for each frequency band at a site compared to the total power at that site; %delta for 2.0-3.8 Hz, %theta for 4.0-7.8 Hz, %alpha for 8.0-12.8 Hz, %beta for 13.0-25.4 Hz) was calculated. Compared with controls, DAT patients showed a significant decrease in %alpha, while significant increases in %theta at all electrodes, and significant increases in %delta at the temporal, parietal and occipital electrodes were observed. The patient group displayed a significant decrease in rCBF and rCMRO 2 in the parietal, temporal and frontal cortices, but the reduction in rCMRO 2 was less remarkable than that of rCBF. %Theta at P3, O1 and O2 showed a significant negative correlation with rCBF, and %theta at P3, O1showed a significant negative correlation with rCMRO 2 . %Delta at P3, P4 and T5 was significantly negatively correlated with rCBF in the corresponding regions, and %alpha at almost all the electrodes (except O1, F3, P3) was significantly positively correlated with rCBF in the corresponding regions. %Delta and %alpha did not show any significant correlation with rCMRO 2 . (author)

Higher theta and alpha1 coherence when listening to Vedic recitation compared to coherence during Transcendental Meditation practice.

Science.gov (United States)

Travis, Frederick; Parim, Niyazi; Shrivastava, Amrita

2017-03-01

This study compared subjective experiences and EEG patterns in 37 subjects when listening to live Vedic recitation and when practicing Transcendental Meditation (TM). Content analysis of experiences when listening to Vedic recitation yielded three higher-order code. Experiences during Vedic recitation were: (1) deeper than during TM practice; (2) experienced as an inner process; and (3) characterized by lively silence. EEG patterns support these higher-order codes. Theta2 and alpha1 frontal, parietal, and frontal-parietal coherence were significantly higher when listening to Vedic recitation, than during TM practice. Theta2 coherence is seen when attending to internal mental processes. Higher theta2 coherence supports subjects' descriptions that the Vedic recitations were "not external sounds but internal vibrations." Alpha1 coherence is reported during pure consciousness experiences during TM practice. Higher alpha1 coherence supports subjects' descriptions that they "experienced a depth of experience, rarely experienced even during deep TM practice." These data support the utility of listening to Vedic recitation to culture deep inner experiences. Copyright © 2017 Elsevier Inc. All rights reserved.

Human brain networks in physiological aging: a graph theoretical analysis of cortical connectivity from EEG data.

Science.gov (United States)

Vecchio, Fabrizio; Miraglia, Francesca; Bramanti, Placido; Rossini, Paolo Maria

2014-01-01

Modern analysis of electroencephalographic (EEG) rhythms provides information on dynamic brain connectivity. To test the hypothesis that aging processes modulate the brain connectivity network, EEG recording was conducted on 113 healthy volunteers. They were divided into three groups in accordance with their ages: 36 Young (15-45 years), 46 Adult (50-70 years), and 31 Elderly (>70 years). To evaluate the stability of the investigated parameters, a subgroup of 10 subjects underwent a second EEG recording two weeks later. Graph theory functions were applied to the undirected and weighted networks obtained by the lagged linear coherence evaluated by eLORETA on cortical sources. EEG frequency bands of interest were: delta (2-4 Hz), theta (4-8 Hz), alpha1 (8-10.5 Hz), alpha2 (10.5-13 Hz), beta1 (13-20 Hz), beta2 (20-30 Hz), and gamma (30-40 Hz). The spectral connectivity analysis of cortical sources showed that the normalized Characteristic Path Length (λ) presented the pattern Young > Adult>Elderly in the higher alpha band. Elderly also showed a greater increase in delta and theta bands than Young. The correlation between age and λ showed that higher ages corresponded to higher λ in delta and theta and lower in the alpha2 band; this pattern reflects the age-related modulation of higher (alpha) and decreased (delta) connectivity. The Normalized Clustering coefficient (γ) and small-world network modeling (σ) showed non-significant age-modulation. Evidence from the present study suggests that graph theory can aid in the analysis of connectivity patterns estimated from EEG and can facilitate the study of the physiological and pathological brain aging features of functional connectivity networks.

Theta Phase Synchronization Is the Glue that Binds Human Associative Memory.

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Clouter, Andrew; Shapiro, Kimron L; Hanslmayr, Simon

2017-10-23

Episodic memories are information-rich, often multisensory events that rely on binding different elements [1]. The elements that will constitute a memory episode are processed in specialized but distinct brain modules. The binding of these elements is most likely mediated by fast-acting long-term potentiation (LTP), which relies on the precise timing of neural activity [2]. Theta oscillations in the hippocampus orchestrate such timing as demonstrated by animal studies in vitro [3, 4] and in vivo [5, 6], suggesting a causal role of theta activity for the formation of complex memory episodes, but direct evidence from humans is missing. Here, we show that human episodic memory formation depends on phase synchrony between different sensory cortices at the theta frequency. By modulating the luminance of visual stimuli and the amplitude of auditory stimuli, we directly manipulated the degree of phase synchrony between visual and auditory cortices. Memory for sound-movie associations was significantly better when the stimuli were presented in phase compared to out of phase. This effect was specific to theta (4 Hz) and did not occur in slower (1.7 Hz) or faster (10.5 Hz) frequencies. These findings provide the first direct evidence that episodic memory formation in humans relies on a theta-specific synchronization mechanism. Copyright © 2017 Elsevier Ltd. All rights reserved.

alpha(4)beta(7) independent pathway for CD8(+) T cell-mediated intestinal immunity to rotavirus.

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Kuklin, N A; Rott, L; Darling, J; Campbell, J J; Franco, M; Feng, N; Müller, W; Wagner, N; Altman, J; Butcher, E C; Greenberg, H B

2000-12-01

Rotavirus (RV), which replicates exclusively in cells of the small intestine, is the most important cause of severe diarrhea in young children worldwide. Using a mouse model, we show that expression of the intestinal homing integrin alpha(4)ss(7) is not essential for CD8(+) T cells to migrate to the intestine or provide immunity to RV. Mice deficient in ss7 expression (ss7(-/-)) and unable to express alpha(4)ss(7) integrin were found to clear RV as quickly as wild-type (wt) animals. Depletion of CD8(+) T cells in ss7(-/-) animals prolonged viral shedding, and transfer of immune ss7(-/-) CD8(+) T cells into chronically infected Rag-2-deficient mice resolved RV infection as efficiently as wt CD8(+) T cells. Paradoxically, alpha(4)ss(7)(hi) memory CD8(+) T cells purified from wt mice that had been orally immunized cleared RV more efficiently than alpha(4)ss(7)(low) CD8(+) T cells. We explained this apparent contradiction by demonstrating that expression of alpha(4)ss(7) on effector CD8(+) T cells depends upon the site of initial antigen exposure: oral immunization generates RV-specific CD8(+) T cells primarily of an alpha(4)ss(7)(hi) phenotype, but subcutaneous immunization yields both alpha(4)ss(7)(hi) and alpha(4)ss(7)(low) immune CD8(+) T cells with anti-RV effector capabilities. Thus, alpha(4)ss(7) facilitates normal intestinal immune trafficking to the gut, but it is not required for effective CD8(+) T cell immunity.

Index of Theta/Alpha Ratio of the Quantitative Electroencephalogram in Alzheimer's Disease: A Case-Control Study.

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Fahimi, Golshan; Tabatabaei, Seyed Mahmoud; Fahimi, Elnaz; Rajebi, Hamid

2017-08-01

Alzheimer's disease (AD) is a devastating neurodegenerative disorder in human beings associated with cognitive, behavioral and motor impairments. The main symptom of AD is dementia, which causes difficulties in carrying out daily practices. Brain waves are altered in people with AD. Relative indices of brain waves can be beneficial in the diagnosis of AD. In this case-control study, 50 patients with AD and 50 matched healthy individuals were enrolled in case and control groups respectively. With recording and analyzing of brain waves with the utilization of quantitative electroencephalogram (QEEG), index of theta/alpha ratio was assessed in both groups. The index of theta/alpha ratio was significantly higher in patients with AD in comparison to healthy individuals (Pratio obtained by QEEG provides a non-invasive diagnostic marker of AD, which may be helpful in identification of non-advanced disease in susceptible individuals.

Expected reward modulates encoding-related theta activity before an event.

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Gruber, Matthias J; Watrous, Andrew J; Ekstrom, Arne D; Ranganath, Charan; Otten, Leun J

2013-01-01

Oscillatory brain activity in the theta frequency range (4-8 Hz) before the onset of an event has been shown to affect the likelihood of successfully encoding the event into memory. Recent work has also indicated that frontal theta activity might be modulated by reward, but it is not clear how reward expectancy, anticipatory theta activity, and memory formation might be related. Here, we used scalp electroencephalography (EEG) to assess the relationship between these factors. EEG was recorded from healthy adults while they memorized a series of words. Each word was preceded by a cue that indicated whether a high or low monetary reward would be earned if the word was successfully remembered in a later recognition test. Frontal theta power between the presentation of the reward cue and the onset of a word was predictive of later memory for the word, but only in the high reward condition. No theta differences were observed before word onset following low reward cues. The magnitude of prestimulus encoding-related theta activity in the high reward condition was correlated with the number of high reward words that were later confidently recognized. These findings provide strong evidence for a link between reward expectancy, theta activity, and memory encoding. Theta activity before event onset seems to be especially important for the encoding of motivationally significant stimuli. One possibility is that dopaminergic activity during reward anticipation mediates frontal theta activity related to memory. Copyright © 2012 Elsevier Inc. All rights reserved.

Gender difference in the theta/alpha ratio during the induction of peaceful audiovisual modalities.

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Yang, Chia-Yen; Lin, Ching-Po

2015-09-01

Gender differences in emotional perception have been found in numerous psychological and psychophysiological studies. The conducting modalities in diverse characteristics of different sensory systems make it interesting to determine how cooperation and competition contribute to emotional experiences. We have previously estimated the bias from the match attributes of auditory and visual modalities and revealed specific brain activity frequency patterns related to a peaceful mood. In that multimodality experiment, we focused on how inner-quiet information is processed in the human brain, and found evidence of auditory domination from the theta-band activity. However, a simple quantitative description of these three frequency bands is lacking, and no studies have assessed the effects of peacefulness on the emotional state. Therefore, the aim of this study was to use magnetoencephalography to determine if gender differences exist (and when and where) in the frequency interactions underpinning the perception of peacefulness. This study provides evidence of auditory and visual domination in perceptual bias during multimodality processing of peaceful consciousness. The results of power ratio analyses suggest that the values of the theta/alpha ratio are associated with a modality as well as hemispheric asymmetries in the anterior-to-posterior direction, which shift from right to left with the auditory to visual stimulations in a peaceful mood. This means that the theta/alpha ratio might be useful for evaluating emotion. Moreover, the difference was found to be most pronounced for auditory domination and visual sensitivity in the female group.

Regional Patterns of Elevated Alpha and High-Frequency Electroencephalographic Activity during Nonrapid Eye Movement Sleep in Chronic Insomnia: A Pilot Study.

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Riedner, Brady A; Goldstein, Michael R; Plante, David T; Rumble, Meredith E; Ferrarelli, Fabio; Tononi, Giulio; Benca, Ruth M

2016-04-01

To examine nonrapid eye movement (NREM) sleep in insomnia using high-density electroencephalography (EEG). All-night sleep recordings with 256 channel high-density EEG were analyzed for 8 insomnia subjects (5 females) and 8 sex and age-matched controls without sleep complaints. Spectral analyses were conducted using unpaired t-tests and topographical differences between groups were assessed using statistical non-parametric mapping. Five minute segments of deep NREM sleep were further analyzed using sLORETA cortical source imaging. The initial topographic analysis of all-night NREM sleep EEG revealed that insomnia subjects had more high-frequency EEG activity (> 16 Hz) compared to good sleeping controls and that the difference between groups was widespread across the scalp. In addition, the analysis also showed that there was a more circumscribed difference in theta (4-8 Hz) and alpha (8-12 Hz) power bands between groups. When deep NREM sleep (N3) was examined separately, the high-frequency difference between groups diminished, whereas the higher regional alpha activity in insomnia subjects persisted. Source imaging analysis demonstrated that sensory and sensorimotor cortical areas consistently exhibited elevated levels of alpha activity during deep NREM sleep in insomnia subjects relative to good sleeping controls. These results suggest that even during the deepest stage of sleep, sensory and sensorimotor areas in insomnia subjects may still be relatively active compared to control subjects and to the rest of the sleeping brain. © 2016 Associated Professional Sleep Societies, LLC.

Eating breakfast enhances the efficiency of neural networks engaged during mental arithmetic in school-aged children.

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Pivik, R T; Tennal, Kevin B; Chapman, Stephen D; Gu, Yuyuan

2012-06-25

To determine the influence of a morning meal on complex mental functions in children (8-11 y), time-frequency analyses were applied to electroencephalographic (EEG) activity recorded while children solved simple addition problems after an overnight fast and again after having either eaten or skipped breakfast. Power of low frequency EEG activity [2 Hertz (Hz) bands in the 2-12 Hz range] was determined from recordings over frontal and parietal brain regions associated with mathematical thinking during mental calculation of correctly answered problems. Analyses were adjusted for background variables known to influence or reflect the development of mathematical skills, i.e., age and measures of math competence and math fluency. Relative to fed children, those who continued to fast showed greater power increases in upper theta (6-8 Hz) and both alpha bands (8-10 Hz; 10-12 Hz) across sites. Increased theta suggests greater demands on working memory. Increased alpha may facilitate task-essential activity by suppressing non-task-essential activity. Fasting children also had greater delta (2-4 Hz) and greater lower-theta (4-6 Hz) power in left frontal recordings-indicating a region-specific emphasis on both working memory for mental calculation (theta) and activation of processes that suppress interfering activity (delta). Fed children also showed a significant increase in correct responses while children who continued to fast did not. Taken together the findings suggest that neural network activity involved in processing numerical information is functionally enhanced and performance is improved in children who have eaten breakfast, whereas greater mental effort is required for this mathematical thinking in children who skip breakfast. Copyright © 2012 Elsevier Inc. All rights reserved.

Transient reduction in theta power caused by interictal spikes in human temporal lobe epilepsy.

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Manling Ge; Jundan Guo; Yangyang Xing; Zhiguo Feng; Weide Lu; Xinxin Ma; Yuehua Geng; Xin Zhang

2017-07-01

The inhibitory impacts of spikes on LFP theta rhythms(4-8Hz) are investigated around sporadic spikes(SSs) based on intracerebral EEG of 4 REM sleep patients with temporal lobe epilepsy(TLE) under the pre-surgical monitoring. Sequential interictal spikes in both genesis area and extended propagation pathway are collected, that, SSs genesis only in anterior hippocampus(aH)(possible propagation pathway in Entorhinal cortex(EC)), only in EC(possible propagation pathway in aH), and in both aH and EC synchronously. Instantaneous theta power was estimated by using Gabor wavelet transform, and theta power level was estimated by averaged over time and frequency before SSs(350ms pre-spike) and after SSs(350ms post-spike). The inhibitory effect around spikes was evaluated by the ratio of theta power level difference between pre-spike and post-spike to pre-spike theta power level. The findings were that theta power level was reduced across SSs, and the effects were more sever in the case of SSs in both aH and EC synchronously than either SSs only in EC or SSs only in aH. It is concluded that interictal spikes impair LFP theta rhythms transiently and directly. The work suggests that the reduction of theta power after the interictal spike might be an evaluation indicator of damage of epilepsy to human cognitive rhythms.

Distributed Attention Is Implemented through Theta-Rhythmic Gamma Modulation.

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Landau, Ayelet Nina; Schreyer, Helene Marianne; van Pelt, Stan; Fries, Pascal

2015-08-31

When subjects monitor a single location, visual target detection depends on the pre-target phase of an ∼8 Hz brain rhythm. When multiple locations are monitored, performance decrements suggest a division of the 8 Hz rhythm over the number of locations, indicating that different locations are sequentially sampled. Indeed, when subjects monitor two locations, performance benefits alternate at a 4 Hz rhythm. These performance alternations were revealed after a reset of attention to one location. Although resets are common and important events for attention, it is unknown whether, in the absence of resets, ongoing attention samples stimuli in alternation. Here, we examined whether spatially specific attentional sampling can be revealed by ongoing pre-target brain rhythms. Visually induced gamma-band activity plays a role in spatial attention. Therefore, we hypothesized that performance on two simultaneously monitored stimuli can be predicted by a 4 Hz modulation of gamma-band activity. Brain rhythms were assessed with magnetoencephalography (MEG) while subjects monitored bilateral grating stimuli for a unilateral target event. The corresponding contralateral gamma-band responses were subtracted from each other to isolate spatially selective, target-related fluctuations. The resulting lateralized gamma-band activity (LGA) showed opposite pre-target 4 Hz phases for detected versus missed targets. The 4 Hz phase of pre-target LGA accounted for a 14.5% modulation in performance. These findings suggest that spatial attention is a theta-rhythmic sampling process that is continuously ongoing, with each sampling cycle being implemented through gamma-band synchrony. Copyright © 2015 Elsevier Ltd. All rights reserved.

EEG source reconstruction reveals frontal-parietal dynamics of spatial conflict processing.

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Cohen, Michael X; Ridderinkhof, K Richard

2013-01-01

Cognitive control requires the suppression of distracting information in order to focus on task-relevant information. We applied EEG source reconstruction via time-frequency linear constrained minimum variance beamforming to help elucidate the neural mechanisms involved in spatial conflict processing. Human subjects performed a Simon task, in which conflict was induced by incongruence between spatial location and response hand. We found an early (∼200 ms post-stimulus) conflict modulation in stimulus-contralateral parietal gamma (30-50 Hz), followed by a later alpha-band (8-12 Hz) conflict modulation, suggesting an early detection of spatial conflict and inhibition of spatial location processing. Inter-regional connectivity analyses assessed via cross-frequency coupling of theta (4-8 Hz), alpha, and gamma power revealed conflict-induced shifts in cortical network interactions: Congruent trials (relative to incongruent trials) had stronger coupling between frontal theta and stimulus-contrahemifield parietal alpha/gamma power, whereas incongruent trials had increased theta coupling between medial frontal and lateral frontal regions. These findings shed new light into the large-scale network dynamics of spatial conflict processing, and how those networks are shaped by oscillatory interactions.

EEG source reconstruction reveals frontal-parietal dynamics of spatial conflict processing.

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Michael X Cohen

Full Text Available Cognitive control requires the suppression of distracting information in order to focus on task-relevant information. We applied EEG source reconstruction via time-frequency linear constrained minimum variance beamforming to help elucidate the neural mechanisms involved in spatial conflict processing. Human subjects performed a Simon task, in which conflict was induced by incongruence between spatial location and response hand. We found an early (∼200 ms post-stimulus conflict modulation in stimulus-contralateral parietal gamma (30-50 Hz, followed by a later alpha-band (8-12 Hz conflict modulation, suggesting an early detection of spatial conflict and inhibition of spatial location processing. Inter-regional connectivity analyses assessed via cross-frequency coupling of theta (4-8 Hz, alpha, and gamma power revealed conflict-induced shifts in cortical network interactions: Congruent trials (relative to incongruent trials had stronger coupling between frontal theta and stimulus-contrahemifield parietal alpha/gamma power, whereas incongruent trials had increased theta coupling between medial frontal and lateral frontal regions. These findings shed new light into the large-scale network dynamics of spatial conflict processing, and how those networks are shaped by oscillatory interactions.

EEG Source Reconstruction Reveals Frontal-Parietal Dynamics of Spatial Conflict Processing

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Cohen, Michael X; Ridderinkhof, K. Richard

2013-01-01

Cognitive control requires the suppression of distracting information in order to focus on task-relevant information. We applied EEG source reconstruction via time-frequency linear constrained minimum variance beamforming to help elucidate the neural mechanisms involved in spatial conflict processing. Human subjects performed a Simon task, in which conflict was induced by incongruence between spatial location and response hand. We found an early (∼200 ms post-stimulus) conflict modulation in stimulus-contralateral parietal gamma (30–50 Hz), followed by a later alpha-band (8–12 Hz) conflict modulation, suggesting an early detection of spatial conflict and inhibition of spatial location processing. Inter-regional connectivity analyses assessed via cross-frequency coupling of theta (4–8 Hz), alpha, and gamma power revealed conflict-induced shifts in cortical network interactions: Congruent trials (relative to incongruent trials) had stronger coupling between frontal theta and stimulus-contrahemifield parietal alpha/gamma power, whereas incongruent trials had increased theta coupling between medial frontal and lateral frontal regions. These findings shed new light into the large-scale network dynamics of spatial conflict processing, and how those networks are shaped by oscillatory interactions. PMID:23451201

Cortical theta wanes for language.

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Hermes, Dora; Miller, Kai J; Vansteensel, Mariska J; Edwards, Erik; Ferrier, Cyrille H; Bleichner, Martin G; van Rijen, Peter C; Aarnoutse, Erik J; Ramsey, Nick F

2014-01-15

The role of low frequency oscillations in language areas is not yet understood. Using ECoG in six human subjects, we studied whether different language regions show prominent power changes in a specific rhythm, in similar manner as the alpha rhythm shows the most prominent power changes in visual areas. Broca's area and temporal language areas were localized in individual subjects using fMRI. In these areas, the theta rhythm showed the most pronounced power changes and theta power decreased significantly during verb generation. To better understand the role of this language-related theta decrease, we then studied the interaction between low frequencies and local neuronal activity reflected in high frequencies. Amplitude-amplitude correlations showed that theta power correlated negatively with high frequency activity, specifically across verb generation trials. Phase-amplitude coupling showed that during control trials, high frequency power was coupled to theta phase, but this coupling decreased significantly during verb generation trials. These results suggest a dynamic interaction between the neuronal mechanisms underlying the theta rhythm and local neuronal activity in language areas. As visual areas show a pronounced alpha rhythm that may reflect pulsed inhibition, language regions show a pronounced theta rhythm with highly similar features. © 2013.

Functional localization and effective connectivity of cortical theta and alpha oscillatory activity during an attention task

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Yuichi Kitaura

Full Text Available Objectives: The aim of this paper is to investigate cortical electric neuronal activity as an indicator of brain function, in a mental arithmetic task that requires sustained attention, as compared to the resting state condition. The two questions of interest are the cortical localization of different oscillatory activities, and the directional effective flow of oscillatory activity between regions of interest, in the task condition compared to resting state. In particular, theta and alpha activity are of interest here, due to their important role in attention processing. Methods: We adapted mental arithmetic as an attention ask in this study. Eyes closed 61-channel EEG was recorded in 14 participants during resting and in a mental arithmetic task (“serial sevens subtraction”. Functional localization and connectivity analyses were based on cortical signals of electric neuronal activity estimated with sLORETA (standardized low resolution electromagnetic tomography. Functional localization was based on the comparison of the cortical distributions of the generators of oscillatory activity between task and resting conditions. Assessment of effective connectivity was based on the iCoh (isolated effective coherence method, which provides an appropriate frequency decomposition of the directional flow of oscillatory activity between brain regions. Nine regions of interest comprising nodes from the dorsal and ventral attention networks were selected for the connectivity analysis. Results: Cortical spectral density distribution comparing task minus rest showed significant activity increase in medial prefrontal areas and decreased activity in left parietal lobe for the theta band, and decreased activity in parietal-occipital regions for the alpha1 band. At a global level, connections among right hemispheric nodes were predominantly decreased during the task condition, while connections among left hemispheric nodes were predominantly increased. At more

Regional Patterns of Elevated Alpha and High-Frequency Electroencephalographic Activity during Nonrapid Eye Movement Sleep in Chronic Insomnia: A Pilot Study

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Riedner, Brady A.; Goldstein, Michael R.; Plante, David T.; Rumble, Meredith E.; Ferrarelli, Fabio; Tononi, Giulio; Benca, Ruth M.

2016-01-01

Study Objectives: To examine nonrapid eye movement (NREM) sleep in insomnia using high-density electroencephalography (EEG). Methods: All-night sleep recordings with 256 channel high-density EEG were analyzed for 8 insomnia subjects (5 females) and 8 sex and age-matched controls without sleep complaints. Spectral analyses were conducted using unpaired t-tests and topographical differences between groups were assessed using statistical non-parametric mapping. Five minute segments of deep NREM sleep were further analyzed using sLORETA cortical source imaging. Results: The initial topographic analysis of all-night NREM sleep EEG revealed that insomnia subjects had more high-frequency EEG activity (> 16 Hz) compared to good sleeping controls and that the difference between groups was widespread across the scalp. In addition, the analysis also showed that there was a more circumscribed difference in theta (4–8 Hz) and alpha (8–12 Hz) power bands between groups. When deep NREM sleep (N3) was examined separately, the high-frequency difference between groups diminished, whereas the higher regional alpha activity in insomnia subjects persisted. Source imaging analysis demonstrated that sensory and sensorimotor cortical areas consistently exhibited elevated levels of alpha activity during deep NREM sleep in insomnia subjects relative to good sleeping controls. Conclusions: These results suggest that even during the deepest stage of sleep, sensory and sensorimotor areas in insomnia subjects may still be relatively active compared to control subjects and to the rest of the sleeping brain. Citation: Riedner BA, Goldstein MR, Plante DT, Rumble ME, Ferrarelli F, Tononi G, Benca RM. Regional patterns of elevated alpha and high-frequency electroencephalographic activity during nonrapid eye movement sleep in chronic insomnia: a pilot study. SLEEP 2016;39(4):801–812. PMID:26943465

Increased frontal electroencephalogram theta amplitude in patients with anorexia nervosa compared to healthy controls

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Hestad KA

2016-09-01

Full Text Available Knut A Hestad,1–3 Siri Weider,3,4 Kristian Bernhard Nilsen,5–7 Marit Sæbø Indredavik,8,9 Trond Sand7,10 1Department of Research, Innlandet Hospital Trust, Brumunddal, Norway; 2Department of Public Health, Hedmark University of Applied Sciences, Elverum, Norway; 3Department of Psychology, Faculty of Social Sciences and Technology Management, Norwegian University of Science and Technology (NTNU, Trondheim, Norway; 4Department of Psychiatry, Specialised Unit for Eating Disorder Patients, Levanger Hospital, Health Trust Nord-Trøndelag, Levanger, Norway; 5Department of Neuroscience, Norwegian University of Science and Technology (NTNU, Trondheim, Norway; 6Department of Work Psychology and Physiology, National Institute of Occupational Health, Oslo, Norway; 7Department of Neurology, Section for Clinical Neurophysiology, Oslo University Hospital, Ullevål, Oslo, Norway; 8Regional Centre for Child and Youth Mental Health and Child Welfare, Faculty of Medicine, Norwegian University of Science and Technology (NTNU, Trondheim, Norway; 9Department of Child and Adolescent Psychiatry, St Olavs Hospital, Trondheim University Hospital, Trondheim, Norway; 10Department of Neurology and Clinical Neurophysiology, St Olavs Hospital, Trondheim University Hospital, Trondheim, Norway Objective: To conduct a blind study of quantitative electroencephalogram-band amplitudes in patients with anorexia nervosa (AN and healthy controls.Methods: Twenty-one patients with AN and 24 controls were examined with eyes-closed 16-channel electroencephalogram. Main variables were absolute alpha, theta, and delta amplitudes in frontal, temporal, and posterior regions.Results: There were no significant differences between the AN patients and controls regarding absolute regional band amplitudes in µV. Borderline significance was found for anterior theta (P=0.051. Significantly increased left and right frontal electrode theta amplitude was found in AN patients (F3, P=0.014; F4, P

Intermittent 20-HZ-photic stimulation leads to a uniform reduction of alpha-global field power in healthy volunteers.

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Rau, R; Raschka, C; Koch, H J

2001-01-01

19-channel-EEGs were recorded from scalp surface of 30 healthy subjects (16m, 14f, mean age: 34 ys, SD: 11.7 ys) at rest and under IPS (Intermittent Photic Stimulation) at rates of 5, 10 and 20 Hertz (Hz). Digitalized data underwent spectral analysis with fast fourier transfomation (FFT) yielding the basis for the computation of global field power (GFP). For quantification GFP values in the frequency ranges of 5, 10 and 20 Hz at rest were divided by the corresponding data gained under IPS. While ratios from PDE data showed no stable parameter due to high interindividual variability, ratios of alpha-power turned out to be uniform in all subjects: IPS at 20 Hz always led to a suppression of alpha-power. Dividing alpha-GFP at rest by alpha-GFP under 20-Hz IPS thus resulted in a ratio paradigma.

Quantum thetas on noncommutative T4 from embeddings into lattice

International Nuclear Information System (INIS)

Chang-Young, Ee; Kim, Hoil

2007-01-01

In this paper, we investigate the theta vector and quantum theta function over noncommutative T 4 from the embedding of RxZ 2 . Manin has constructed the quantum theta functions from the lattice embedding into vector space (x finite group). We extend Manin's construction of the quantum theta function to the embedding of vector space x lattice case. We find that the holomorphic theta vector exists only over the vector space part of the embedding, and over the lattice part we can only impose the condition for the Schwartz function. The quantum theta function built on this partial theta vector satisfies the requirement of the quantum theta function. However, two subsequent quantum translations from the embedding into the lattice part are nonadditive, contrary to the additivity of those from the vector space part

Bursts of occipital theta and alpha amplitude preceding alternation and repetition trials in a task-switching experiment

NARCIS (Netherlands)

Gladwin, T.E.; De Jong, Ritske

The instantaneous amplitude of the theta and alpha bands of the electroencephalogram (EEG) was studied during preparation periods in a task-switching experiment. Subjects had to switch between tasks in which they were to respond to either the visual or the auditory component of the stimulus. 11-13

The utility of quantitative electroencephalography and Integrated Visual and Auditory Continuous Performance Test as auxiliary tools for the Attention Deficit Hyperactivity Disorder diagnosis.

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Kim, JunWon; Lee, YoungSik; Han, DougHyun; Min, KyungJoon; Kim, DoHyun; Lee, ChangWon

2015-03-01

This study investigated the clinical utility of quantitative electroencephalography (QEEG) and the Integrated Visual and Auditory Continuous Performance Test (IVA+CPT) as auxiliary tools for assessing Attention Deficit Hyperactivity Disorder (ADHD). All of 157 subjects were assessed using the Korean version of the Diagnostic Interview Schedule for Children Version IV (DISC-IV). We measured EGG absolute power in 21 channels and conducted IVA+CPT. We analyzed QEEG according to the Hz range: delta (1-4Hz), theta (4-8Hz), slow alpha (8-10Hz), fast alpha (10-13.5Hz), and beta (13.5-30Hz). To remove artifacts, independent component analysis was conducted (ICA), and the tester confirmed the results again. All of the IVA+CPT quotients showed significant differences between the ADHD and control groups. The ADHD group showed significantly increased delta and theta activity compared with the control group. The z-scores of theta were negatively correlated with the scores of IVA+CPT in ADHD combined type, and those of beta were positively correlated. IVA+CPT and QEEG significantly discriminated between ADHD and control groups. The commission error of IVA+CPT showed an accuracy of 82.1%, and the omission error of IVA+CPT showed an accuracy of 78.6%. The IVA+CPT and QEEG are expected to be valuable tools for aiding ADHD diagnosis accurately. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Changes in Alpha Frequency and Power of the Electroencephalogram during Volatile-Based General Anesthesia

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Darren Hight

2017-05-01

Full Text Available Oscillations in the electroencephalogram (EEG at the alpha frequency (8–12 Hz are thought to be ubiquitous during surgical anesthesia, but the details of how this oscillation responds to ongoing changes in volatile anesthetic concentration have not been well characterized. It is not known how often alpha oscillations are absent in the clinical context, how sensitively alpha frequency and power respond to changes in anesthetic concentration, and what effect increased age has on alpha frequency. Bipolar EEG was recorded frontally from 305 patients undergoing surgery with sevoflurane or desflurane providing general anesthesia. A new method of detecting the presence of alpha oscillations based on the stability of the rate of change of the peak frequency in the alpha range was developed. Linear concentration-response curves were fitted to assess the sensitivity of alpha power and frequency measures to changing levels of anesthesia. Alpha oscillations were seen to be inexplicably absent in around 4% of patients. Maximal alpha power increased with increasing volatile anesthetic concentrations in half of the patients, and decreased in the remaining patients. Alpha frequency decreased with increasing anesthetic concentrations in near to 90% of patients. Increasing age was associated with decreased sensitivity to volatile anesthesia concentrations, and with decreased alpha frequency, which sometimes transitioned into the theta range (5–7 Hz. While peak alpha frequency shows a consistent slowing to increasing volatile concentrations, the peak power of the oscillation does not, suggesting that frequency might be more informative of depth of anesthesia than traditional power based measures during volatile-based anesthesia. The alpha oscillation becomes slower with increasing age, even when the decreased anesthetic needs of older patients were taken into account.

Coherent oscillatory networks supporting short-term memory retention.

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Payne, Lisa; Kounios, John

2009-01-09

Accumulating evidence suggests that top-down processes, reflected by frontal-midline theta-band (4-8 Hz) electroencephalogram (EEG) oscillations, strengthen the activation of a memory set during short-term memory (STM) retention. In addition, the amplitude of posterior alpha-band (8-13 Hz) oscillations during STM retention is thought to reflect a mechanism that protects fragile STM activations from interference by gating bottom-up sensory inputs. The present study addressed two important questions about these phenomena. First, why have previous studies not consistently found memory set-size effects on frontal-midline theta? Second, how does posterior alpha participate in STM retention? To answer these questions, large-scale network connectivity during STM retention was examined by computing EEG wavelet coherence during the retention period of a modified Sternberg task using visually-presented letters as stimuli. The results showed (a) increasing theta-band coherence between frontal-midline and left temporal-parietal sites with increasing memory load, and (b) increasing alpha-band coherence between midline parietal and left temporal/parietal sites with increasing memory load. These findings support the view that theta-band coherence, rather than amplitude, is the key factor in selective top-down strengthening of the memory set and demonstrate that posterior alpha-band oscillations associated with sensory gating are involved in STM retention by participating in the STM network.

Hippocampal Theta-Gamma Coupling Reflects State-Dependent Information Processing in Decision Making.

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Amemiya, Seiichiro; Redish, A David

2018-03-20

During decision making, hippocampal activity encodes information sometimes about present and sometimes about potential future plans. The mechanisms underlying this transition remain unknown. Building on the evidence that gamma oscillations at different frequencies (low gamma [LG], 30-55 Hz; high gamma [HG], 60-90 Hz; and epsilon, 100-140 Hz) reflect inputs from different circuits, we identified how changes in those frequencies reflect different information-processing states. Using a unique noradrenergic manipulation by clonidine, which shifted both neural representations and gamma states, we found that future representations depended on gamma components. These changes were identifiable on each cycle of theta as asymmetries in the theta cycle, which arose from changes within the ratio of LG and HG power and the underlying phases of those gamma rhythms within the theta cycle. These changes in asymmetry of the theta cycle reflected changes in representations of present and future on each theta cycle. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Visual working memory load-related changes in neural activity and functional connectivity.

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Ling Li

Full Text Available BACKGROUND: Visual working memory (VWM helps us store visual information to prepare for subsequent behavior. The neuronal mechanisms for sustaining coherent visual information and the mechanisms for limited VWM capacity have remained uncharacterized. Although numerous studies have utilized behavioral accuracy, neural activity, and connectivity to explore the mechanism of VWM retention, little is known about the load-related changes in functional connectivity for hemi-field VWM retention. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we recorded electroencephalography (EEG from 14 normal young adults while they performed a bilateral visual field memory task. Subjects had more rapid and accurate responses to the left visual field (LVF memory condition. The difference in mean amplitude between the ipsilateral and contralateral event-related potential (ERP at parietal-occipital electrodes in retention interval period was obtained with six different memory loads. Functional connectivity between 128 scalp regions was measured by EEG phase synchronization in the theta- (4-8 Hz, alpha- (8-12 Hz, beta- (12-32 Hz, and gamma- (32-40 Hz frequency bands. The resulting matrices were converted to graphs, and mean degree, clustering coefficient and shortest path length was computed as a function of memory load. The results showed that brain networks of theta-, alpha-, beta-, and gamma- frequency bands were load-dependent and visual-field dependent. The networks of theta- and alpha- bands phase synchrony were most predominant in retention period for right visual field (RVF WM than for LVF WM. Furthermore, only for RVF memory condition, brain network density of theta-band during the retention interval were linked to the delay of behavior reaction time, and the topological property of alpha-band network was negative correlation with behavior accuracy. CONCLUSIONS/SIGNIFICANCE: We suggest that the differences in theta- and alpha- bands between LVF and RVF

Visual Working Memory Load-Related Changes in Neural Activity and Functional Connectivity

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Li, Ling; Zhang, Jin-Xiang; Jiang, Tao

2011-01-01

Background Visual working memory (VWM) helps us store visual information to prepare for subsequent behavior. The neuronal mechanisms for sustaining coherent visual information and the mechanisms for limited VWM capacity have remained uncharacterized. Although numerous studies have utilized behavioral accuracy, neural activity, and connectivity to explore the mechanism of VWM retention, little is known about the load-related changes in functional connectivity for hemi-field VWM retention. Methodology/Principal Findings In this study, we recorded electroencephalography (EEG) from 14 normal young adults while they performed a bilateral visual field memory task. Subjects had more rapid and accurate responses to the left visual field (LVF) memory condition. The difference in mean amplitude between the ipsilateral and contralateral event-related potential (ERP) at parietal-occipital electrodes in retention interval period was obtained with six different memory loads. Functional connectivity between 128 scalp regions was measured by EEG phase synchronization in the theta- (4–8 Hz), alpha- (8–12 Hz), beta- (12–32 Hz), and gamma- (32–40 Hz) frequency bands. The resulting matrices were converted to graphs, and mean degree, clustering coefficient and shortest path length was computed as a function of memory load. The results showed that brain networks of theta-, alpha-, beta-, and gamma- frequency bands were load-dependent and visual-field dependent. The networks of theta- and alpha- bands phase synchrony were most predominant in retention period for right visual field (RVF) WM than for LVF WM. Furthermore, only for RVF memory condition, brain network density of theta-band during the retention interval were linked to the delay of behavior reaction time, and the topological property of alpha-band network was negative correlation with behavior accuracy. Conclusions/Significance We suggest that the differences in theta- and alpha- bands between LVF and RVF conditions in

Differential effects of 10-Hz and 40-Hz transcranial alternating current stimulation (tACS) on endogenous versus exogenous attention.

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Hopfinger, Joseph B; Parsons, Jonathan; Fröhlich, Flavio

2017-04-01

Previous electrophysiological studies implicate both alpha (8-12 Hz) and gamma (>30 Hz) neural oscillations in the mechanisms of selective attention. Here, participants preformed two separate visual attention tasks, one endogenous and one exogenous, while transcranial alternating current stimulation (tACS), at 10 Hz, 40 Hz, or sham, was applied to the right parietal lobe. Our results provide new evidence for the roles of gamma and alpha oscillations in voluntary versus involuntary shifts of attention. Gamma (40 Hz) stimulation resulted in improved disengagement from invalidly cued targets in the endogenous attention task, whereas alpha stimulation (10 Hz) had no effect on endogenous attention, but increased the exogenous cuing effect. These findings agree with previous studies suggesting that right inferior parietal regions may be especially important for the disengagement of attention, and go further to provide details about the specific type of oscillatory neural activity within that brain region that is differentially involved in endogenous versus exogenous attention. Our results also have potential implications for the plasticity and training of attention systems.

Investigation of attention deficit hyperactivity disorder (ADHD) sub-types in children via EEG frequency domain analysis.

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Aldemir, Ramazan; Demirci, Esra; Per, Huseyin; Canpolat, Mehmet; Özmen, Sevgi; Tokmakçı, Mahmut

2018-04-01

To investigate the frequency domain effects and changes in electroencephalography (EEG) signals in children diagnosed with attention deficit hyperactivity disorder (ADHD). The study contains 40 children. All children were between the ages of 7 and 12 years. Participants were classified into four groups which were ADHD (n=20), ADHD-I (ADHD-Inattentive type) (n=10), ADHD-C (ADHD-Combined type) (n=10), and control (n=20) groups. In this study, the frequency domain of EEG signals for ADHD, subtypes and control groups were analyzed and compared using Matlab software. The mean age of the ADHD children's group was 8.7 years and the control group 9.1 years. Spectral analysis of mean power (μV 2 ) and relative-mean power (%) was carried out for four different frequency bands: delta (0--4 Hz), theta (4--8 Hz), alpha (8--13 Hz) and beta (13--32 Hz). The ADHD and subtypes of ADHD-I, and ADHD-C groups had higher average power value of delta and theta band than that of control group. However, this is not the case for alpha and beta bands. Increases in delta/beta ratio and statistical significance were found only between ADHD-I and control group, and in delta/beta, theta/delta ratio statistical significance values were found to exist between ADHD-C and control group. EEG analyzes can be used as an alternative method when ADHD subgroups are identified.

Auditory conflict resolution correlates with medial-lateral frontal theta/alpha phase synchrony.

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Huang, Samantha; Rossi, Stephanie; Hämäläinen, Matti; Ahveninen, Jyrki

2014-01-01

When multiple persons speak simultaneously, it may be difficult for the listener to direct attention to correct sound objects among conflicting ones. This could occur, for example, in an emergency situation in which one hears conflicting instructions and the loudest, instead of the wisest, voice prevails. Here, we used cortically-constrained oscillatory MEG/EEG estimates to examine how different brain regions, including caudal anterior cingulate (cACC) and dorsolateral prefrontal cortices (DLPFC), work together to resolve these kinds of auditory conflicts. During an auditory flanker interference task, subjects were presented with sound patterns consisting of three different voices, from three different directions (45° left, straight ahead, 45° right), sounding out either the letters "A" or "O". They were asked to discriminate which sound was presented centrally and ignore the flanking distracters that were phonetically either congruent (50%) or incongruent (50%) with the target. Our cortical MEG/EEG oscillatory estimates demonstrated a direct relationship between performance and brain activity, showing that efficient conflict resolution, as measured with reduced conflict-induced RT lags, is predicted by theta/alpha phase coupling between cACC and right lateral frontal cortex regions intersecting the right frontal eye fields (FEF) and DLPFC, as well as by increased pre-stimulus gamma (60-110 Hz) power in the left inferior fontal cortex. Notably, cACC connectivity patterns that correlated with behavioral conflict-resolution measures were found during both the pre-stimulus and the pre-response periods. Our data provide evidence that, instead of being only transiently activated upon conflict detection, cACC is involved in sustained engagement of attentional resources required for effective sound object selection performance.

Auditory Conflict Resolution Correlates with Medial–Lateral Frontal Theta/Alpha Phase Synchrony

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Huang, Samantha; Rossi, Stephanie; Hämäläinen, Matti; Ahveninen, Jyrki

2014-01-01

When multiple persons speak simultaneously, it may be difficult for the listener to direct attention to correct sound objects among conflicting ones. This could occur, for example, in an emergency situation in which one hears conflicting instructions and the loudest, instead of the wisest, voice prevails. Here, we used cortically-constrained oscillatory MEG/EEG estimates to examine how different brain regions, including caudal anterior cingulate (cACC) and dorsolateral prefrontal cortices (DLPFC), work together to resolve these kinds of auditory conflicts. During an auditory flanker interference task, subjects were presented with sound patterns consisting of three different voices, from three different directions (45° left, straight ahead, 45° right), sounding out either the letters “A” or “O”. They were asked to discriminate which sound was presented centrally and ignore the flanking distracters that were phonetically either congruent (50%) or incongruent (50%) with the target. Our cortical MEG/EEG oscillatory estimates demonstrated a direct relationship between performance and brain activity, showing that efficient conflict resolution, as measured with reduced conflict-induced RT lags, is predicted by theta/alpha phase coupling between cACC and right lateral frontal cortex regions intersecting the right frontal eye fields (FEF) and DLPFC, as well as by increased pre-stimulus gamma (60–110 Hz) power in the left inferior fontal cortex. Notably, cACC connectivity patterns that correlated with behavioral conflict-resolution measures were found during both the pre-stimulus and the pre-response periods. Our data provide evidence that, instead of being only transiently activated upon conflict detection, cACC is involved in sustained engagement of attentional resources required for effective sound object selection performance. PMID:25343503

Auditory conflict resolution correlates with medial-lateral frontal theta/alpha phase synchrony.

Directory of Open Access Journals (Sweden)

Samantha Huang

Full Text Available When multiple persons speak simultaneously, it may be difficult for the listener to direct attention to correct sound objects among conflicting ones. This could occur, for example, in an emergency situation in which one hears conflicting instructions and the loudest, instead of the wisest, voice prevails. Here, we used cortically-constrained oscillatory MEG/EEG estimates to examine how different brain regions, including caudal anterior cingulate (cACC and dorsolateral prefrontal cortices (DLPFC, work together to resolve these kinds of auditory conflicts. During an auditory flanker interference task, subjects were presented with sound patterns consisting of three different voices, from three different directions (45° left, straight ahead, 45° right, sounding out either the letters "A" or "O". They were asked to discriminate which sound was presented centrally and ignore the flanking distracters that were phonetically either congruent (50% or incongruent (50% with the target. Our cortical MEG/EEG oscillatory estimates demonstrated a direct relationship between performance and brain activity, showing that efficient conflict resolution, as measured with reduced conflict-induced RT lags, is predicted by theta/alpha phase coupling between cACC and right lateral frontal cortex regions intersecting the right frontal eye fields (FEF and DLPFC, as well as by increased pre-stimulus gamma (60-110 Hz power in the left inferior fontal cortex. Notably, cACC connectivity patterns that correlated with behavioral conflict-resolution measures were found during both the pre-stimulus and the pre-response periods. Our data provide evidence that, instead of being only transiently activated upon conflict detection, cACC is involved in sustained engagement of attentional resources required for effective sound object selection performance.

Theta oscillations locked to intended actions rhythmically modulate perception.

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Tomassini, Alice; Ambrogioni, Luca; Medendorp, W Pieter; Maris, Eric

2017-07-07

Ongoing brain oscillations are known to influence perception, and to be reset by exogenous stimulations. Voluntary action is also accompanied by prominent rhythmic activity, and recent behavioral evidence suggests that this might be coupled with perception. Here, we reveal the neurophysiological underpinnings of this sensorimotor coupling in humans. We link the trial-by-trial dynamics of EEG oscillatory activity during movement preparation to the corresponding dynamics in perception, for two unrelated visual and motor tasks. The phase of theta oscillations (~4 Hz) predicts perceptual performance, even >1 s before movement. Moreover, theta oscillations are phase-locked to the onset of the movement. Remarkably, the alignment of theta phase and its perceptual relevance unfold with similar non-monotonic profiles, suggesting their relatedness. The present work shows that perception and movement initiation are automatically synchronized since the early stages of motor planning through neuronal oscillatory activity in the theta range.

Learning curves of theta/beta neurofeedback in children with ADHD.

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Janssen, Tieme W P; Bink, Marleen; Weeda, Wouter D; Geladé, Katleen; van Mourik, Rosa; Maras, Athanasios; Oosterlaan, Jaap

2017-05-01

Neurofeedback is widely applied as non-pharmacological intervention aimed at reducing symptoms of ADHD, even though efficacy has not been unequivocally established. Neuronal changes during the neurofeedback intervention that resemble learning can provide crucial evidence for the feasibility and specificity of this intervention. A total of 38 children (aged between 7 and 13 years) with a DSM-IV-TR diagnosis of ADHD, completed on average 29 sessions of theta (4-8 Hz)/beta (13-20 Hz) neurofeedback training. Dependent variables included training-related measures as well as theta and beta power during baseline and training runs for each session. Learning effects were analyzed both within and between sessions. To further specify findings, individual learning curves were explored and correlated with behavioral changes in ADHD symptoms. Over the course of the training, there was a linear increase in participants' mean training level, highest obtained training level and the number of earned credits (range b = 0.059, -0.750, p neurofeedback, although a lack of behavioral correlates may indicate insufficient transfer to daily functioning, or to confounding reinforcement of electromyographic activity. This trial is registered at the US National Institutes of Health (ClinicalTrials.gov, ref. no: NCT01363544); https://clinicaltrials.gov/show/NCT01363544 .

Harnessing the power of theta: natural manipulations of cognitive performance during hippocampal theta-contingent eyeblink conditioning

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Hoffmann, Loren C.; Cicchese, Joseph J.; Berry, Stephen D.

2015-01-01

Neurobiological oscillations are regarded as essential to normal information processing, including coordination and timing of cells and assemblies within structures as well as in long feedback loops of distributed neural systems. The hippocampal theta rhythm is a 3–12 Hz oscillatory potential observed during cognitive processes ranging from spatial navigation to associative learning. The lower range, 3–7 Hz, can occur during immobility and depends upon the integrity of cholinergic forebrain systems. Several studies have shown that the amount of pre-training theta in the rabbit strongly predicts the acquisition rate of classical eyeblink conditioning and that impairment of this system substantially slows the rate of learning. Our lab has used a brain-computer interface (BCI) that delivers eyeblink conditioning trials contingent upon the explicit presence or absence of hippocampal theta. A behavioral benefit of theta-contingent training has been demonstrated in both delay and trace forms of the paradigm with a two- to four-fold increase in learning speed. This behavioral effect is accompanied by enhanced amplitude and synchrony of hippocampal local field potential (LFP)s, multi-unit excitation, and single-unit response patterns that depend on theta state. Additionally, training in the presence of hippocampal theta has led to increases in the salience of tone-induced unit firing patterns in the medial prefrontal cortex, followed by persistent multi-unit activity during the trace interval. In cerebellum, rhythmicity and precise synchrony of stimulus time-locked LFPs with those of hippocampus occur preferentially under the theta condition. Here we review these findings, integrate them into current models of hippocampal-dependent learning and suggest how improvement in our understanding of neurobiological oscillations is critical for theories of medial temporal lobe processes underlying intact and pathological learning. PMID:25918501

Harnessing the power of theta: natural manipulations of cognitive performance during hippocampal theta-contingent eyeblink conditioning.

Science.gov (United States)

Hoffmann, Loren C; Cicchese, Joseph J; Berry, Stephen D

2015-01-01

Neurobiological oscillations are regarded as essential to normal information processing, including coordination and timing of cells and assemblies within structures as well as in long feedback loops of distributed neural systems. The hippocampal theta rhythm is a 3-12 Hz oscillatory potential observed during cognitive processes ranging from spatial navigation to associative learning. The lower range, 3-7 Hz, can occur during immobility and depends upon the integrity of cholinergic forebrain systems. Several studies have shown that the amount of pre-training theta in the rabbit strongly predicts the acquisition rate of classical eyeblink conditioning and that impairment of this system substantially slows the rate of learning. Our lab has used a brain-computer interface (BCI) that delivers eyeblink conditioning trials contingent upon the explicit presence or absence of hippocampal theta. A behavioral benefit of theta-contingent training has been demonstrated in both delay and trace forms of the paradigm with a two- to four-fold increase in learning speed. This behavioral effect is accompanied by enhanced amplitude and synchrony of hippocampal local field potential (LFP)s, multi-unit excitation, and single-unit response patterns that depend on theta state. Additionally, training in the presence of hippocampal theta has led to increases in the salience of tone-induced unit firing patterns in the medial prefrontal cortex, followed by persistent multi-unit activity during the trace interval. In cerebellum, rhythmicity and precise synchrony of stimulus time-locked LFPs with those of hippocampus occur preferentially under the theta condition. Here we review these findings, integrate them into current models of hippocampal-dependent learning and suggest how improvement in our understanding of neurobiological oscillations is critical for theories of medial temporal lobe processes underlying intact and pathological learning.

Binaural beats increase interhemispheric alpha-band coherence between auditory cortices.

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Solcà, Marco; Mottaz, Anaïs; Guggisberg, Adrian G

2016-02-01

Binaural beats (BBs) are an auditory illusion occurring when two tones of slightly different frequency are presented separately to each ear. BBs have been suggested to alter physiological and cognitive processes through synchronization of the brain hemispheres. To test this, we recorded electroencephalograms (EEG) at rest and while participants listened to BBs or a monaural control condition during which both tones were presented to both ears. We calculated for each condition the interhemispheric coherence, which expressed the synchrony between neural oscillations of both hemispheres. Compared to monaural beats and resting state, BBs enhanced interhemispheric coherence between the auditory cortices. Beat frequencies in the alpha (10 Hz) and theta (4 Hz) frequency range both increased interhemispheric coherence selectively at alpha frequencies. In a second experiment, we evaluated whether this coherence increase has a behavioral aftereffect on binaural listening. No effects were observed in a dichotic digit task performed immediately after BBs presentation. Our results suggest that BBs enhance alpha-band oscillation synchrony between the auditory cortices during auditory stimulation. This effect seems to reflect binaural integration rather than entrainment. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrophysiological correlates of higher states of consciousness during sleep in long-term practitioners of the Transcendental Meditation program.

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Mason, L I; Alexander, C N; Travis, F T; Marsh, G; Orme-Johnson, D W; Gackenbach, J; Mason, D C; Rainforth, M; Walton, K G

1997-02-01

Standard ambulatory night sleep electroencephalograph (EEG) of 11 long-term practitioners of the Transcendental Meditation (TM) program reporting "higher states of consciousness" during sleep (the experimental group) was compared to that of nine short-term practitioners and 11 non-practitioners. EEG tracings during stages 3 and 4 sleep showed the experimental group to have: 1) theta-alpha activity simultaneously with delta activity and 2) decreased chin electromyograph (EMG) during deep sleep (p = 0.002) compared to short-term practitioners. Spectral analysis fast Fourier transform (FFT) data of the first three cycles showed that: 3) the experimental subjects had significantly greater theta 2 (6-8 Hz)-alpha 1 (8-10 Hz) relative power during stages 3 and 4 than the combined control groups [t(30) = 5.5, p = 0.0000008] with no difference in time in delta; 4) there was a graded difference across groups during stages 3 and 4 in theta 2-alpha 1 power, with experimentals having greater power than short-term practitioners, who in turn had greater power than non-practitioners [t(30) = 5.08, p = 0.00002]; and 5) experimentals also had increased rapid eye movement (REM) density during REM periods compared to short-term practitioners (p = 0.04). Previous studies have found increased theta-alpha EEG activity during reported periods of "transcendental consciousness" during the TM technique. In the Vedic tradition, as described by Maharishi Mahesh Yogi, transcendental consciousness is the first of a sequence of higher states. The maintenance of transcendental consciousness along with deep sleep is said to be a distinctive criterion of further, stabilized higher states of consciousness. The findings of this study are interpreted as physiological support for this model.

Changes in hippocampal theta rhythm and their correlations with speed during different phases of voluntary wheel running in rats.

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Li, J-Y; Kuo, T B J; Hsieh, I-T; Yang, C C H

2012-06-28

Hippocampal theta rhythm (4-12 Hz) can be observed during locomotor behavior, but findings on the relationship between locomotion speed and theta frequency are inconsistent if not contradictory. The inconsistency may be because of the difficulties that previous analyses and protocols have had excluding the effects of behavior training. We recorded the first or second voluntary wheel running each day, and assumed that theta frequency and activity are correlated with speed in different running phases. By simultaneously recording electroencephalography, physical activity, and wheel running speed, this experiment explored the theta oscillations during spontaneous running of the 12-h dark period. The recording was completely wireless and allowed the animal to run freely while being recorded in the wheel. Theta frequency and theta power of middle frequency were elevated before running and theta frequency, theta power of middle frequency, physical activity, and running speed maintained persistently high levels during running. The slopes of the theta frequency and theta activity (4-9.5 Hz) during the initial running were different compared to the same values during subsequent running. During the initial running, the running speed was positively correlated with theta frequency and with theta power of middle frequency. Over the 12-h dark period, the running speed did not positively correlate with theta frequency but was significantly correlated with theta power of middle frequency. Thus, theta frequency was associated with running speed only at the initiation of running. Furthermore, theta power of middle frequency was associated with speed and with physical activity during running when chronological order was not taken into consideration. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Responses to tonic heat pain in the ongoing EEG under conditions of controlled attention.

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Giehl, Janet; Meyer-Brandis, Gesa; Kunz, Miriam; Lautenbacher, Stefan

2014-03-01

To confirm the existence of an ongoing electroencephalogram (EEG) pattern that is truly suggestive of pain, tonic heat pain was induced by small heat pulses at 1 °C above the pain threshold and compared to slightly less intense tonic non-painful heat pulses at 1 °C below the pain threshold. Twenty healthy subjects rated the sensation intensity during thermal stimulation. Possible confounding effects of attention were thoroughly controlled for by testing in four conditions: (1) focus of attention directed ipsilateral or (2) contralateral to the side of the stimulation, (3) control without a side preference, and (4) no control of attention at all. EEG was recorded via eight leads according to the 10/20 convention. Absolute power was computed for the frequency bands delta (0.5-4 Hz), theta (4-8 Hz), alpha1 (8-11 Hz), alpha2 (11-14 Hz), beta1 (14-25 Hz), and beta2 (25-35 Hz). Ratings were clearly distinct between the heat and pain conditions and suggestive for heat and pain sensations. Manipulation of attention proved to be successful by producing effects on the ratings and on the EEG activity (with lower ratings and lower EEG activity (theta, beta1, 2) over central areas for side-focused attention). During pain stimulation, lower central alpha1 and alpha2 activity and higher right-parietal and right-occipital delta power were observed compared to heat stimulation. This EEG pattern was not influenced by the manipulation of attention. Since the two types of stimuli (pain, heat) were subjectively felt differently although stimulation intensities were nearby, we conclude that this EEG pattern is clearly suggestive of pain.

Ih tunes theta/gamma oscillations and cross-frequency coupling in an in silico CA3 model.

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Samuel A Neymotin

Full Text Available Ih channels are uniquely positioned to act as neuromodulatory control points for tuning hippocampal theta (4-12 Hz and gamma (25 Hz oscillations, oscillations which are thought to have importance for organization of information flow. contributes to neuronal membrane resonance and resting membrane potential, and is modulated by second messengers. We investigated oscillatory control using a multiscale computer model of hippocampal CA3, where each cell class (pyramidal, basket, and oriens-lacunosum moleculare cells, contained type-appropriate isoforms of . Our model demonstrated that modulation of pyramidal and basket allows tuning theta and gamma oscillation frequency and amplitude. Pyramidal also controlled cross-frequency coupling (CFC and allowed shifting gamma generation towards particular phases of the theta cycle, effected via 's ability to set pyramidal excitability. Our model predicts that in vivo neuromodulatory control of allows flexibly controlling CFC and the timing of gamma discharges at particular theta phases.

Theta-rhythmic drive between medial septum and hippocampus in slow-wave sleep and microarousal: a Granger causality analysis.

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Kang, D; Ding, M; Topchiy, I; Shifflett, L; Kocsis, B

2015-11-01

Medial septum (MS) plays a critical role in controlling the electrical activity of the hippocampus (HIPP). In particular, theta-rhythmic burst firing of MS neurons is thought to drive lasting HIPP theta oscillations in rats during waking motor activity and REM sleep. Less is known about MS-HIPP interactions in nontheta states such as non-REM sleep, in which HIPP theta oscillations are absent but theta-rhythmic burst firing in subsets of MS neurons is preserved. The present study used Granger causality (GC) to examine the interaction patterns between MS and HIPP in slow-wave sleep (SWS, a nontheta state) and during its short interruptions called microarousals (a transient theta state). We found that during SWS, while GC revealed a unidirectional MS→HIPP influence over a wide frequency band (2-12 Hz, maximum: ∼8 Hz), there was no theta peak in the hippocampal power spectra, indicating a lack of theta activity in HIPP. In contrast, during microarousals, theta peaks were seen in both MS and HIPP power spectra and were accompanied by bidirectional GC with MS→HIPP and HIPP→MS theta drives being of equal magnitude. Thus GC in a nontheta state (SWS) vs. a theta state (microarousal) primarily differed in the level of HIPP→MS. The present findings suggest a modification of our understanding of the role of MS as the theta generator in two regards. First, a MS→HIPP theta drive does not necessarily induce theta field oscillations in the hippocampus, as found in SWS. Second, HIPP theta oscillations entail bidirectional theta-rhythmic interactions between MS and HIPP. Copyright © 2015 the American Physiological Society.

An Exploration of Physiological Responses to the Native American Flute

OpenAIRE

Miller, Eric B.; Goss, Clinton F.

2014-01-01

This pilot study explored physiological responses to playing and listening to the Native American flute. Autonomic, electroencephalographic (EEG), and heart rate variability (HRV) metrics were recorded while participants (N = 15) played flutes and listened to several styles of music. Flute playing was accompanied by an 84% increase in HRV (p < .001). EEG theta (4-8 Hz) activity increased while playing flutes (p = .007) and alpha (8-12 Hz) increased while playing lower-pitched flutes (p = .009...

The effects of individualized theta burst stimulation on the excitability of the human motor system.

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Brownjohn, Philip W; Reynolds, John N J; Matheson, Natalie; Fox, Jonathan; Shemmell, Jonathan B H

2014-01-01

Theta burst stimulation (TBS) is a pattern of repetitive transcranial magnetic stimulation that has been demonstrated to facilitate or suppress human corticospinal excitability when applied intermittently (iTBS) or continuously (cTBS), respectively. While the fundamental pattern of TBS, consisting of bursts of 50 Hz stimulation repeated at a 5 Hz theta frequency, induces synaptic plasticity in animals and in vitro preparations, the relationship between TBS and underlying cortical firing patterns in the human cortex has not been elucidated. To compare the effects of 5 Hz iTBS and cTBS with individualized TBS paradigms on corticospinal excitability and intracortical inhibitory circuits. Participants received standard and individualized iTBS (iTBS 5; iTBS I) and cTBS (cTBS 5; cTBS I), and sham TBS, in a randomised design. For individualized paradigms, the 5 Hz theta component of the TBS pattern was replaced by the dominant cortical frequency (4-16 Hz; upper frequency restricted by technical limitations) for each individual. We report that iTBS 5 and iTBS I both significantly facilitated motor evoked potential (MEP) amplitude to a similar extent. Unexpectedly, cTBS 5 and cTBS I failed to suppress MEP amplitude. None of the active TBS protocols had any significant effects on intracortical circuits when compared with sham TBS. In summary, iTBS facilitated MEP amplitude, an effect that was not improved by individualizing the theta component of the TBS pattern, while cTBS, a reportedly inhibitory paradigm, produced no change, or facilitation of MEP amplitude in our hands. Copyright © 2014 Elsevier Inc. All rights reserved.

Estimation of localization and dipole moment of alpha- and theta-rhythm sources by cluster analysis in healthy subjects and schizophrenics

NARCIS (Netherlands)

Verkhlyutov, VM; Shchuchkin, YV; Ushakov, VL; Strelets, VB; Pirogov, YA

2006-01-01

In 12 healthy subjects and 9 schizophrenic patients in the background conditions (with eyes closed) EEG was recorded from 16 standard derivations (10-20 system) during 3 min. The record underwent the spectral analysis detecting alpha- and theta-frequency bands. After the preliminary narrow band

Fast entrainment of human electroencephalogram to a theta-band photic flicker during successful memory encoding

Directory of Open Access Journals (Sweden)

Naoyuki eSato

2013-05-01

Full Text Available Theta band power (4-8Hz in the scalp electroencephalogram (EEG is thought to be stronger during memory encoding for subsequently remembered items than for forgotten items. According to simultaneous EEG-functional magnetic resonance imaging (fMRI measurements, the memory-dependent EEG theta is associated with multiple regions of the brain. This suggests that the multiple regions cooperate with EEG theta synchronization during successful memory encoding. However, a question still remains: What kind of neural dynamic organizes such a memory-dependent global network? In this study, the modulation of the EEG theta entrainment property during successful encoding was hypothesized to lead to EEG theta synchronization among a distributed network. Then, a transient response of EEG theta to a theta-band photic flicker with a short duration was evaluated during memory encoding. In the results, flicker-induced EEG power increased and decreased with a time constant of several hundred milliseconds following the onset and the offset of the flicker, respectively. Importantly, the offset response of EEG power was found to be significantly decreased during successful encoding. Moreover, the offset response of the phase locking index was also found to associate with memory performance. According to computational simulations, the results are interpreted as a smaller time constant (i.e., faster response of a driven harmonic oscillator rather than a change in the spontaneous oscillatory input. This suggests that the fast response of EEG theta forms a global EEG theta network among memory-related regions during successful encoding, and it contributes to a flexible formation of the network along the time course.

Fast entrainment of human electroencephalogram to a theta-band photic flicker during successful memory encoding.

Science.gov (United States)

Sato, Naoyuki

2013-01-01

Theta band power (4-8 Hz) in the scalp electroencephalogram (EEG) is thought to be stronger during memory encoding for subsequently remembered items than for forgotten items. According to simultaneous EEG-functional magnetic resonance imaging (fMRI) measurements, the memory-dependent EEG theta is associated with multiple regions of the brain. This suggests that the multiple regions cooperate with EEG theta synchronization during successful memory encoding. However, a question still remains: What kind of neural dynamic organizes such a memory-dependent global network? In this study, the modulation of the EEG theta entrainment property during successful encoding was hypothesized to lead to EEG theta synchronization among a distributed network. Then, a transient response of EEG theta to a theta-band photic flicker with a short duration was evaluated during memory encoding. In the results, flicker-induced EEG power increased and decreased with a time constant of several hundred milliseconds following the onset and the offset of the flicker, respectively. Importantly, the offset response of EEG power was found to be significantly decreased during successful encoding. Moreover, the offset response of the phase locking index was also found to associate with memory performance. According to computational simulations, the results are interpreted as a smaller time constant (i.e., faster response) of a driven harmonic oscillator rather than a change in the spontaneous oscillatory input. This suggests that the fast response of EEG theta forms a global EEG theta network among memory-related regions during successful encoding, and it contributes to a flexible formation of the network along the time course.

(No) Time for control: Frontal theta dynamics reveal the cost of temporally guided conflict anticipation

NARCIS (Netherlands)

van Driel, J.; Swart, J.C.; Egner, T.; Ridderinkhof, K.R.; Cohen, M.

2015-01-01

During situations of response conflict, cognitive control is characterized by prefrontal theta-band (3- to 8-Hz) activity. It has been shown that cognitive control can be triggered proactively by contextual cues that predict conflict. Here, we investigated whether a pretrial preparation interval

(No) time for control: frontal theta dynamics reveal the cost of temporally guided conflict anticipation

NARCIS (Netherlands)

van Driel, J.; Swart, J.C.; Egner, T.; Ridderinkhof, K.R.; Cohen, M.X.

2015-01-01

During situations of response conflict, cognitive control is characterized by prefrontal theta-band (3- to 8-Hz) activity. It has been shown that cognitive control can be triggered proactively by contextual cues that predict conflict. Here, we investigated whether a pretrial preparation interval

Efficiency at rest: magnetoencephalographic resting-state connectivity and individual differences in verbal working memory.

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del Río, David; Cuesta, Pablo; Bajo, Ricardo; García-Pacios, Javier; López-Higes, Ramón; del-Pozo, Francisco; Maestú, Fernando

2012-11-01

Inter-individual differences in cognitive performance are based on an efficient use of task-related brain resources. However, little is known yet on how these differences might be reflected on resting-state brain networks. Here we used Magnetoencephalography resting-state recordings to assess the relationship between a behavioral measurement of verbal working memory and functional connectivity as measured through Mutual Information. We studied theta (4-8 Hz), low alpha (8-10 Hz), high alpha (10-13 Hz), low beta (13-18 Hz) and high beta (18-30 Hz) frequency bands. A higher verbal working memory capacity was associated with a lower mutual information in the low alpha band, prominently among right-anterior and left-lateral sensors. The results suggest that an efficient brain organization in the domain of verbal working memory might be related to a lower resting-state functional connectivity across large-scale brain networks possibly involving right prefrontal and left perisylvian areas. Copyright © 2012 Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

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

2013-01-01

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. (interdisciplinary physics and related areas of science and technology)

alpha-decay spectroscopy of light odd-odd Bi isotopes - II sup 1 sup 8 sup 6 Bi and the new nuclide sup 1 sup 8 sup 4 Bi

CERN Document Server

Andreyev, A N; Ackermann, D; Münzenberg, G; Hessberger, F P; Hofmann, S; Kojouharov, I; Kindler, B; Lommel, B; Huyse, M; Vel, K V D; Duppen, P V; Heyde, Kris L G

2003-01-01

Alpha-decay of the new nuclide sup 1 sup 8 sup 4 Bi has been studied in the complete-fusion reaction sup 9 sup 3 Nb( sup 9 sup 4 Mo, 3n) sup 1 sup 8 sup 4 Bi at the velocity filter SHIP. The evaporation residues were separated in-flight and subsequently identified on the basis of recoil-alpha, recoil-alpha-gamma analysis and excitation functions measurements. Two alpha-decaying isomeric states in sup 1 sup 8 sup 4 Bi with half-life values of 13(2) ms and 6.6(1.5) ms were identified. The alpha-branching ratio of sup 1 sup 8 sup 0 Tl was deduced for the first time as b subalpha = (2-12)%. Improved data on the fine-structure alpha-decay of sup 1 sup 8 sup 6 Bi were obtained in the sup 9 sup 3 Nb( sup 9 sup 5 Mo, 2n) sup 1 sup 8 sup 6 Bi reaction. A similarity of the decay energies and half-life values of sup 1 sup 8 sup 4 sup , sup 1 sup 8 sup 6 Bi is pointed out and a possible explanation for this effect is suggested.

Temporal Courses in EEG Theta and Alpha Activity in the Dynamic Health Qigong Techniques Wu Qin Xi and Liu Zi Jue

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Diana Henz

2018-01-01

Full Text Available Health Qigong is a common technique of Traditional Chinese Medicine applied to strengthen mental and physical health. Several studies report increases in EEG theta and alpha activity after meditative Qigong techniques indicating a relaxed state of mind. To date, little is known on the effects of dynamic Health Qigong techniques that comprise bodily movements on brain activity. In the current study, we compared effects of two dynamic Health Qigong techniques on EEG brain activity. Subjects performed the techniques Wu Qin Xi (five animals play and Liu Zi Jue (six healing sounds in a within-subjects design. Eyes-open and eyes-closed resting EEG was recorded before and immediately after each 15-min practice block. Additionally, the Profile of Mood States (POMS questionnaire was administered at pretest, and after each 15-min practice block. Results show a decrease in alpha activity after 15 min, followed by an increase after 30 min in the Health Qigong technique Liu Zi Jue. Theta activity was decreased after 15 min, followed by an increase after 30 min in the technique Wu Qin Xi. Results of the POMS indicated an increased vigor-activity level with decreased fatigue and tension-anxiety levels in both techniques after 30 min of practice. Our results demonstrate different temporal dynamics in EEG theta and alpha activity for the Health Qigong techniques Wu Qin Xi and Liu Zi Jue. We hypothesize that the found brain activation patterns result from different attentional focusing styles and breathing techniques performed during the investigated Health Qigong techniques.

Bilateral 5 Hz transcranial alternating current stimulation on fronto-temporal areas modulates resting-state EEG.

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D'Atri, Aurora; Romano, Claudia; Gorgoni, Maurizio; Scarpelli, Serena; Alfonsi, Valentina; Ferrara, Michele; Ferlazzo, Fabio; Rossini, Paolo Maria; De Gennaro, Luigi

2017-11-15

Rhythmic non-invasive brain stimulations are promising tools to modulate brain activity by entraining neural oscillations in specific cortical networks. The aim of the study was to assess the possibility to influence the neural circuits of the wake-sleep transition in awake subjects via a bilateral transcranial alternating current stimulation at 5 Hz (θ-tACS) on fronto-temporal areas. 25 healthy volunteers participated in two within-subject sessions (θ-tACS and sham), one week apart and in counterbalanced order. We assessed the stimulation effects on cortical EEG activity (28 derivations) and self-reported sleepiness (Karolinska Sleepiness Scale). θ-tACS induced significant increases of the theta activity in temporo-parieto-occipital areas and centro-frontal increases in the alpha activity compared to sham but failed to induce any online effect on sleepiness. Since the total energy delivered in the sham condition was much less than in the active θ-tACS, the current data are unable to isolate the specific effect of entrained theta oscillatory activity per se on sleepiness scores. On this basis, we concluded that θ-tACS modulated theta and alpha EEG activity with a topography consistent with high sleep pressure conditions. However, no causal relation can be traced on the basis of the current results between these rhythms and changes on sleepiness.

Why don't you like me? Midfrontal theta power in response to unexpected peer rejection feedback.

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van der Molen, M J W; Dekkers, L M S; Westenberg, P M; van der Veen, F M; van der Molen, M W

2017-02-01

Social connectedness theory posits that the brain processes social rejection as a threat to survival. Recent electrophysiological evidence suggests that midfrontal theta (4-8Hz) oscillations in the EEG provide a window on the processing of social rejection. Here we examined midfrontal theta dynamics (power and inter-trial phase synchrony) during the processing of social evaluative feedback. We employed the Social Judgment paradigm in which 56 undergraduate women (mean age=19.67 years) were asked to communicate their expectancies about being liked vs. disliked by unknown peers. Expectancies were followed by feedback indicating social acceptance vs. rejection. Results revealed a significant increase in EEG theta power to unexpected social rejection feedback. This EEG theta response could be source-localized to brain regions typically reported during activation of the saliency network (i.e., dorsal anterior cingulate cortex, insula, inferior frontal gyrus, frontal pole, and the supplementary motor area). Theta phase dynamics mimicked the behavior of the time-domain averaged feedback-related negativity (FRN) by showing stronger phase synchrony for feedback that was unexpected vs. expected. Theta phase, however, differed from the FRN by also displaying stronger phase synchrony in response to rejection vs. acceptance feedback. Together, this study highlights distinct roles for midfrontal theta power and phase synchrony in response to social evaluative feedback. Our findings contribute to the literature by showing that midfrontal theta oscillatory power is sensitive to social rejection but only when peer rejection is unexpected, and this theta response is governed by a widely distributed neural network implicated in saliency detection and conflict monitoring. Copyright © 2016 Elsevier Inc. All rights reserved.

Local Optogenetic Induction of Fast (20-40 Hz Pyramidal-Interneuron Network Oscillations in the In Vitro and In Vivo CA1 Hippocampus: Modulation by CRF and Enforcement of Perirhinal Theta Activity

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Julien eDine

2016-04-01

Full Text Available The neurophysiological processes that can cause theta-to-gamma frequency range (4-80 Hz network oscillations in the rhinal cortical-hippocampal system and the potential connectivity-based interactions of such forebrain rhythms are a topic of intensive investigation. Here, using selective Channelrhodopsin-2 (ChR2 expression in mouse forebrain glutamatergic cells, we were able to locally, temporally precisely, and reliably induce fast (20-40 Hz field potential oscillations in hippocampal area CA1 in vitro (at 25°C and in vivo (i.e., slightly anaesthetized NEX-Cre-ChR2 mice. As revealed by pharmacological analyses and patch-clamp recordings from pyramidal cells and GABAergic interneurons in vitro, these light-triggered oscillations can exclusively arise from sustained suprathreshold depolarization (~200 ms or longer and feedback inhibition of CA1 pyramidal neurons, as being mandatory for prototypic pyramidal-interneuron network (P-I oscillations. Consistently, the oscillations comprised rhythmically occurring population spikes (generated by pyramidal cells and their frequency increased with increasing spectral power. We further demonstrate that the optogenetically driven CA1 oscillations, which remain stable over repeated evocations, are impaired by the stress hormone corticotropin-releasing factor (CRF, 125 nM in vitro and, even more remarkably, found that they are accompanied by concurrent states of enforced theta activity in the memory-associated perirhinal cortex (PrC in vivo. The latter phenomenon most likely derives from neurotransmission via a known, but poorly studied excitatory CA1PrC pathway. Collectively, our data provide evidence for the existence of a prototypic (CRF-sensitive P-I gamma rhythm generator in area CA1 and suggest that CA1 P-I oscillations can rapidly up-regulate theta activity strength in hippocampus-innervated rhinal networks, at least in the PrC.

Local Optogenetic Induction of Fast (20-40 Hz) Pyramidal-Interneuron Network Oscillations in the In Vitro and In Vivo CA1 Hippocampus: Modulation by CRF and Enforcement of Perirhinal Theta Activity.

Science.gov (United States)

Dine, Julien; Genewsky, Andreas; Hladky, Florian; Wotjak, Carsten T; Deussing, Jan M; Zieglgänsberger, Walter; Chen, Alon; Eder, Matthias

2016-01-01

The neurophysiological processes that can cause theta-to-gamma frequency range (4-80 Hz) network oscillations in the rhinal cortical-hippocampal system and the potential connectivity-based interactions of such forebrain rhythms are a topic of intensive investigation. Here, using selective Channelrhodopsin-2 (ChR2) expression in mouse forebrain glutamatergic cells, we were able to locally, temporally precisely, and reliably induce fast (20-40 Hz) field potential oscillations in hippocampal area CA1 in vitro (at 25°C) and in vivo (i.e., slightly anesthetized NEX-Cre-ChR2 mice). As revealed by pharmacological analyses and patch-clamp recordings from pyramidal cells and GABAergic interneurons in vitro, these light-triggered oscillations can exclusively arise from sustained suprathreshold depolarization (~200 ms or longer) and feedback inhibition of CA1 pyramidal neurons, as being mandatory for prototypic pyramidal-interneuron network (P-I) oscillations. Consistently, the oscillations comprised rhythmically occurring population spikes (generated by pyramidal cells) and their frequency increased with increasing spectral power. We further demonstrate that the optogenetically driven CA1 oscillations, which remain stable over repeated evocations, are impaired by the stress hormone corticotropin-releasing factor (CRF, 125 nM) in vitro and, even more remarkably, found that they are accompanied by concurrent states of enforced theta activity in the memory-associated perirhinal cortex (PrC) in vivo. The latter phenomenon most likely derives from neurotransmission via a known, but poorly studied excitatory CA1→PrC pathway. Collectively, our data provide evidence for the existence of a prototypic (CRF-sensitive) P-I gamma rhythm generator in area CA1 and suggest that CA1 P-I oscillations can rapidly up-regulate theta activity strength in hippocampus-innervated rhinal networks, at least in the PrC.

Binding of benzo(a)pyrene and (+/-)-7 beta,8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9, 10-tetrahydrobenzo(a)pyrene to histones

International Nuclear Information System (INIS)

Sculley, T.B.; Zytkovicz, T.H.

1983-01-01

AKR-2B mouse embryo cells were incubated for 24 hr with [3H]benzo(a)pyrene, and the histones were isolated and analyzed using one- and two-dimensional gel electrophoresis and autoradiography. The results revealed that (a) histones H1, H2A, and H3 incorporated significant amounts of label whereas little or no label was associated with histones H2B and H4 and (b) electrophoresis of the histones in the Triton: acid: urea gel system caused labeled histones to have a slower migration than did the corresponding unlabeled histones. Additional studies such as incubation of (+/-)-7 beta,8 alpha-[3H]dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene with nuclei resulted in radioactive labeling of histones H1, H2A, H2B, and H3 and of high-mobility-group proteins HMG1 and HMG2. The low levels of label associated with histone H4 in the whole-cell and nuclear studies were further investigated by incubating isolated histones with (+/-)-7 beta,8 alpha-[3H]dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene. Under these conditions, negligible amounts of radioactivity were associated with H4, while significant labeling of H1, H2A, H2B, and H3 and other nuclear proteins was observed. The results suggest that factors other than the presence of suitable nucleophilic acceptor sites on the histones may be necessary for carcinogen binding

Functional roles of 10 Hz alpha-band power modulating engagement and disengagement of cortical networks in a complex visual motion task.

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Kunjan D Rana

Full Text Available Alpha band power, particularly at the 10 Hz frequency, is significantly involved in sensory inhibition, attention modulation, and working memory. However, the interactions between cortical areas and their relationship to the different functional roles of the alpha band oscillations are still poorly understood. Here we examined alpha band power and the cortico-cortical interregional phase synchrony in a psychophysical task involving the detection of an object moving in depth by an observer in forward self-motion. Wavelet filtering at the 10 Hz frequency revealed differences in the profile of cortical activation in the visual processing regions (occipital and parietal lobes and in the frontoparietal regions. The alpha rhythm driving the visual processing areas was found to be asynchronous with the frontoparietal regions. These findings suggest a decoupling of the 10 Hz frequency into separate functional roles: sensory inhibition in the visual processing regions and spatial attention in the frontoparietal regions.

Coupling between Theta Oscillations and Cognitive Control Network during Cross-Modal Visual and Auditory Attention: Supramodal vs Modality-Specific Mechanisms.

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Wang, Wuyi; Viswanathan, Shivakumar; Lee, Taraz; Grafton, Scott T

2016-01-01

Cortical theta band oscillations (4-8 Hz) in EEG signals have been shown to be important for a variety of different cognitive control operations in visual attention paradigms. However the synchronization source of these signals as defined by fMRI BOLD activity and the extent to which theta oscillations play a role in multimodal attention remains unknown. Here we investigated the extent to which cross-modal visual and auditory attention impacts theta oscillations. Using a simultaneous EEG-fMRI paradigm, healthy human participants performed an attentional vigilance task with six cross-modal conditions using naturalistic stimuli. To assess supramodal mechanisms, modulation of theta oscillation amplitude for attention to either visual or auditory stimuli was correlated with BOLD activity by conjunction analysis. Negative correlation was localized to cortical regions associated with the default mode network and positively with ventral premotor areas. Modality-associated attention to visual stimuli was marked by a positive correlation of theta and BOLD activity in fronto-parietal area that was not observed in the auditory condition. A positive correlation of theta and BOLD activity was observed in auditory cortex, while a negative correlation of theta and BOLD activity was observed in visual cortex during auditory attention. The data support a supramodal interaction of theta activity with of DMN function, and modality-associated processes within fronto-parietal networks related to top-down theta related cognitive control in cross-modal visual attention. On the other hand, in sensory cortices there are opposing effects of theta activity during cross-modal auditory attention.

Fronto-parietal and fronto-temporal theta phase synchronization for visual and auditory-verbal working memory.

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Kawasaki, Masahiro; Kitajo, Keiichi; Yamaguchi, Yoko

2014-01-01

In humans, theta phase (4-8 Hz) synchronization observed on electroencephalography (EEG) plays an important role in the manipulation of mental representations during working memory (WM) tasks; fronto-temporal synchronization is involved in auditory-verbal WM tasks and fronto-parietal synchronization is involved in visual WM tasks. However, whether or not theta phase synchronization is able to select the to-be-manipulated modalities is uncertain. To address the issue, we recorded EEG data from subjects who were performing auditory-verbal and visual WM tasks; we compared the theta synchronizations when subjects performed either auditory-verbal or visual manipulations in separate WM tasks, or performed both two manipulations in the same WM task. The auditory-verbal WM task required subjects to calculate numbers presented by an auditory-verbal stimulus, whereas the visual WM task required subjects to move a spatial location in a mental representation in response to a visual stimulus. The dual WM task required subjects to manipulate auditory-verbal, visual, or both auditory-verbal and visual representations while maintaining auditory-verbal and visual representations. Our time-frequency EEG analyses revealed significant fronto-temporal theta phase synchronization during auditory-verbal manipulation in both auditory-verbal and auditory-verbal/visual WM tasks, but not during visual manipulation tasks. Similarly, we observed significant fronto-parietal theta phase synchronization during visual manipulation tasks, but not during auditory-verbal manipulation tasks. Moreover, we observed significant synchronization in both the fronto-temporal and fronto-parietal theta signals during simultaneous auditory-verbal/visual manipulations. These findings suggest that theta synchronization seems to flexibly connect the brain areas that manipulate WM.

Fronto-parietal and fronto-temporal theta phase synchronization for visual and auditory-verbal working memory

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Masahiro eKawasaki

2014-03-01

Full Text Available In humans, theta phase (4–8 Hz synchronization observed on electroencephalography (EEG plays an important role in the manipulation of mental representations during working memory (WM tasks; fronto-temporal synchronization is involved in auditory-verbal WM tasks and fronto-parietal synchronization is involved in visual WM tasks. However, whether or not theta phase synchronization is able to select the to-be-manipulated modalities is uncertain. To address the issue, we recorded EEG data from subjects who were performing auditory-verbal and visual WM tasks; we compared the theta synchronizations when subjects performed either auditory-verbal or visual manipulations in separate WM tasks, or performed both two manipulations in the same WM task. The auditory-verbal WM task required subjects to calculate numbers presented by an auditory-verbal stimulus, whereas the visual WM task required subjects to move a spatial location in a mental representation in response to a visual stimulus. The dual WM task required subjects to manipulate auditory-verbal, visual, or both auditory-verbal and visual representations while maintaining auditory-verbal and visual representations. Our time-frequency EEG analyses revealed significant fronto-temporal theta phase synchronization during auditory-verbal manipulation in both auditory-verbal and auditory-verbal/visual WM tasks, but not during visual manipulation tasks. Similarly, we observed significant fronto-parietal theta phase synchronization during visual manipulation tasks, but not during auditory-verbal manipulation tasks. Moreover, we observed significant synchronization in both the fronto-temporal and fronto-parietal theta signals during simultaneous auditory-verbal/visual manipulations. These findings suggest that theta synchronization seems to flexibly connect the brain areas that manipulate WM.

Experimental study of CF4 conical theta pinch plasma expanding into vacuum

International Nuclear Information System (INIS)

Pedrow, P.D.; Nasiruddin, A.M.

1989-01-01

Langmuir probe, photodiode, and optical multichannel analyzer (OMA) measurements have been made on a pulsed CF 4 conical theta pinch plasma. A cloud of CF 4 gas was puffed into a conical theta pinch coil, converted to plasma, and propelled into the vacuum region ahead of the expanding gas cloud. At a position 67 cm away from the conical theta pinch coil, the plasma arrived in separate packets that were about 20 μs in duration. The average drift velocity of these packets corresponded to an energy of about 3 eV. The OMA measurements showed that the second packet contained neutral atomic fluorine as well as charged particles

rTMS of the dorsomedial prefrontal cortex for major depression: safety, tolerability, effectiveness, and outcome predictors for 10 Hz versus intermittent theta-burst stimulation.

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Bakker, Nathan; Shahab, Saba; Giacobbe, Peter; Blumberger, Daniel M; Daskalakis, Zafiris J; Kennedy, Sidney H; Downar, Jonathan

2015-01-01

Conventional rTMS protocols for major depression commonly employ stimulation sessions lasting >30 min. However, recent studies have sought to improve costs, capacities, and outcomes by employing briefer protocols such as theta burst stimulation (iTBS). To compare safety, effectiveness, and outcome predictors for DMPFC-rTMS with 10 Hz (30 min) versus iTBS (6 min) protocols, in a large, naturalistic, retrospective case series. A chart review identified 185 patients with a medication-resistant major depressive episode who underwent 20-30 sessions of DMPFC-rTMS (10 Hz, n = 98; iTBS, n = 87) at a single Canadian clinic from 2011 to 2014. Clinical characteristics of 10 Hz and iTBS patients did not differ prior to treatment, aside from significantly higher age in iTBS patients. A total 7912 runs of DMPFC-rTMS (10 Hz, 4274; iTBS, 3638) were administered, without any seizures or other serious adverse events, and no significant differences in rates of premature discontinuation between groups. Dichotomous outcomes did not differ significantly between groups (Response/remission rates: Beck Depression Inventory-II: 10 Hz, 40.6%/29.2%; iTBS, 43.0%/31.0%. 17-item Hamilton Rating Scale for Depression: 10 Hz, 50.6%/38.5%; iTBS, 48.5%/27.9%). On continuous outcomes, there was no significant difference between groups in pre-treatment or post-treatment scores, or percent improvement on either measure. Mixed-effects modeling revealed no significant group-by-time interaction on either measure. Both 10 Hz and iTBS DMPFC-rTMS appear safe and tolerable at 120% resting motor threshold. The effectiveness of 6 min iTBS and 30 min 10 Hz protocols appears comparable. Randomized trials comparing 10 Hz to iTBS may be warranted. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

The brain matures with stronger functional connectivity and decreased randomness of its network.

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Dirk J A Smit

Full Text Available We investigated the development of the brain's functional connectivity throughout the life span (ages 5 through 71 years by measuring EEG activity in a large population-based sample. Connectivity was established with Synchronization Likelihood. Relative randomness of the connectivity patterns was established with Watts and Strogatz' (1998 graph parameters C (local clustering and L (global path length for alpha (~10 Hz, beta (~20 Hz, and theta (~4 Hz oscillation networks. From childhood to adolescence large increases in connectivity in alpha, theta and beta frequency bands were found that continued at a slower pace into adulthood (peaking at ~50 yrs. Connectivity changes were accompanied by increases in L and C reflecting decreases in network randomness or increased order (peak levels reached at ~18 yrs. Older age (55+ was associated with weakened connectivity. Semi-automatically segmented T1 weighted MRI images of 104 young adults revealed that connectivity was significantly correlated to cerebral white matter volume (alpha oscillations: r = 33, p<01; theta: r = 22, p<05, while path length was related to both white matter (alpha: max. r = 38, p<001 and gray matter (alpha: max. r = 36, p<001; theta: max. r = 36, p<001 volumes. In conclusion, EEG connectivity and graph theoretical network analysis may be used to trace structural and functional development of the brain.

Abnormal-induced theta activity supports early directed-attention network deficits in progressive MCI.

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Deiber, Marie-Pierre; Ibañez, Vicente; Missonnier, Pascal; Herrmann, François; Fazio-Costa, Lara; Gold, Gabriel; Giannakopoulos, Panteleimon

2009-09-01

The electroencephalography (EEG) theta frequency band reacts to memory and selective attention paradigms. Global theta oscillatory activity includes a posterior phase-locked component related to stimulus processing and a frontal-induced component modulated by directed attention. To investigate the presence of early deficits in the directed attention-related network in elderly individuals with mild cognitive impairment (MCI), time-frequency analysis at baseline was used to assess global and induced theta oscillatory activity (4-6Hz) during n-back working memory tasks in 29 individuals with MCI and 24 elderly controls (EC). At 1-year follow-up, 13 MCI patients were still stable and 16 had progressed. Baseline task performance was similar in stable and progressive MCI cases. Induced theta activity at baseline was significantly reduced in progressive MCI as compared to EC and stable MCI in all n-back tasks, which were similar in terms of directed attention requirements. While performance is maintained, the decrease of induced theta activity suggests early deficits in the directed-attention network in progressive MCI, whereas this network is functionally preserved in stable MCI.

Histamine Enhances Theta-Coupled Spiking and Gamma Oscillations in the Medial Entorhinal Cortex Consistent With Successful Spatial Recognition.

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Chen, Quanhui; Luo, Fenlan; Yue, Faguo; Xia, Jianxia; Xiao, Qin; Liao, Xiang; Jiang, Jun; Zhang, Jun; Hu, Bo; Gao, Dong; He, Chao; Hu, Zhian

2017-06-07

Encoding of spatial information in the superficial layers of the medial entorhinal cortex (sMEC) involves theta-modulated spiking and gamma oscillations, as well as spatially tuned grid cells and border cells. Little is known about the role of the arousal-promoting histaminergic system in the modification of information encoded in the sMEC in vivo, and how such histamine-regulated information correlates with behavioral functions. Here, we show that histamine upregulates the neural excitability of a significant proportion of neurons (16.32%, 39.18%, and 52.94% at 30 μM, 300 μM, and 3 mM, respectively) and increases local theta (4-12 Hz) and gamma power (low: 25-48 Hz; high: 60-120 Hz) in the sMEC, through activation of histamine receptor types 1 and 3. During spatial exploration, the strength of theta-modulated firing of putative principal neurons and high gamma oscillations is enhanced about 2-fold by histamine. The histamine-mediated increase of theta phase-locking of spikes and high gamma power is consistent with successful spatial recognition. These results, for the first time, reveal possible mechanisms involving the arousal-promoting histaminergic system in the modulation of spatial cognition. Published by Oxford University Press 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

EEG Spectral Analysis in Serious Gaming: An Ad Hoc Experimental Application

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Minchev Z.

2009-12-01

Full Text Available The application of serious gaming technology in different areas of human knowledge for learning is raising the question of quantitative measurement of the training process quality. In the present paper a pilot study of 10 healthy volunteers' EEG spectra is performed for ad hoc selected game events ('win' and 'lose' via continuous wavelet transform (real and complex on the basis of the Morlet mother wavelet function and S-transformation. The results have shown a general decrease of the alpha rhythms power spectra frequencies for the 'lose' events and increase for the 'win' events. This fact corresponds to an opposite behaviour of the theta rhythm of the players for the same 'win' and 'lose' events. Additionally, the frequency changes in the alpha1 (8-10.5 Hz, alpha2 (10.5-13 Hz and theta2 rhythms (6-8 Hz were supposed to be a phenomena related to positive and negative emotions appearance in the EEG activity of the players regarding the selected 'win' and 'lose' states.

Electroencephalographic precursors of spike-wave discharges in a genetic rat model of absence epilepsy: Power spectrum and coherence EEG analyses.

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Sitnikova, Evgenia; van Luijtelaar, Gilles

2009-04-01

Periods in the electroencephalogram (EEG) that immediately precede the onset of spontaneous spike-wave discharges (SWD) were examined in WAG/Rij rat model of absence epilepsy. Precursors of SWD (preSWD) were classified based on the distribution of EEG power in delta-theta-alpha frequency bands as measured in the frontal cortex. In 95% of preSWD, an elevation of EEG power was detected in delta band (1-4Hz). 73% of preSWD showed high power in theta frequencies (4.5-8Hz); these preSWD might correspond to 5-9Hz oscillations that were found in GAERS before SWD onset [Pinault, D., Vergnes, M., Marescaux, C., 2001. Medium-voltage 5-9Hz oscillations give rise to spike-and-wave discharges in a genetic model of absence epilepsy: in vivo dual extracellular recording of thalamic relay and reticular neurons. Neuroscience 105, 181-201], however, theta component of preSWD in our WAG/Rij rats was not shaped into a single rhythm. It is concluded that a coalescence of delta and theta in the cortex is favorable for the occurrence of SWD. The onset of SWD was associated with strengthening of intracortical and thalamo-cortical coherence in 9.5-14Hz and in double beta frequencies. No features of EEG coherence can be considered as unique for any of preSWD subtype. Reticular and ventroposteromedial thalamic nuclei were strongly coupled even before the onset of SWD. All this suggests that SWD derive from an intermixed delta-theta EEG background; seizure onset associates with reinforcement of intracortical and cortico-thalamic associations.

Molecular characterization of the alpha subunit of complement component C8 (GcC8alpha) in the nurse shark (Ginglymostoma cirratum).

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Aybar, Lydia; Shin, Dong-Ho; Smith, Sylvia L

2009-09-01

Target cell lysis by complement is achieved by the assembly and insertion of the membrane attack complex (MAC) composed of glycoproteins C5b through C9. The lytic activity of shark complement involves functional analogues of mammalian C8 and C9. Mammalian C8 is composed of alpha, beta, and gamma subunits. The subunit structure of shark C8 is not known. This report describes a 2341 nucleotide sequence that translates into a polypeptide of 589 amino acid residues, orthologue to mammalian C8alpha and has the same modular architecture with conserved cysteines forming the peptide bond backbone. The C8gamma-binding cysteine is conserved in the perforin-like domain. Hydrophobicity profile indicates the presence of hydrophobic residues essential for membrane insertion. It shares 41.1% and 47.4% identity with human and Xenopus C8alpha respectively. Southern blot analysis showed GcC8alpha exists as a single copy gene expressed in most tissues except the spleen with the liver being the main site of synthesis. Phylogenetic analysis places it in a clade with C8alpha orthologs and as a sister taxa to the Xenopus. 2009 Elsevier Ltd.

Short-term Beneficial Effects of 12 Sessions of Neurofeedback on Avoidant Personality Accentuation in the Treatment of Alcohol Use Disorder.

Science.gov (United States)

Dalkner, Nina; Unterrainer, Human F; Wood, Guilherme; Skliris, Dimitris; Holasek, Sandra J; Gruzelier, John H; Neuper, Christa

2017-01-01

This study evaluated the effects of alpha/theta neurofeedback on Clinical Personality Accentuations in individuals with alcohol use disorder. Twenty-five males were investigated using a pre-test/post-test design with a waiting-list control group. Participants were randomly assigned either to an experimental group ( n = 13) receiving 12 sessions of neurofeedback twice a week as a treatment adjunct over a period of 6 weeks, or to a control group ( n = 12) receiving treatment as usual. The Inventory of Clinical Personality Accentuations and the NEO-Five-Factor Inventory were applied at pre- and post-test. The neurofeedback protocol focused on enhancement of the EEG alpha (8-12 Hz) and theta (4-7 Hz) and used a visual feedback paradigm. Analyses of covariance showed improvements in Avoidant Personality Accentuation within the experimental group. Our data suggest that 12 sessions of this neurofeedback intervention might be effective in reducing avoidant and stress-related personality traits in patients with alcohol use disorder.

Short-term Beneficial Effects of 12 Sessions of Neurofeedback on Avoidant Personality Accentuation in the Treatment of Alcohol Use Disorder

Directory of Open Access Journals (Sweden)

Nina Dalkner

2017-09-01

Full Text Available This study evaluated the effects of alpha/theta neurofeedback on Clinical Personality Accentuations in individuals with alcohol use disorder. Twenty-five males were investigated using a pre-test/post-test design with a waiting-list control group. Participants were randomly assigned either to an experimental group (n = 13 receiving 12 sessions of neurofeedback twice a week as a treatment adjunct over a period of 6 weeks, or to a control group (n = 12 receiving treatment as usual. The Inventory of Clinical Personality Accentuations and the NEO-Five-Factor Inventory were applied at pre- and post-test. The neurofeedback protocol focused on enhancement of the EEG alpha (8–12 Hz and theta (4–7 Hz and used a visual feedback paradigm. Analyses of covariance showed improvements in Avoidant Personality Accentuation within the experimental group. Our data suggest that 12 sessions of this neurofeedback intervention might be effective in reducing avoidant and stress-related personality traits in patients with alcohol use disorder.

Lateralized theta wave connectivity and language performance in 2- to 5-year-old children.

Science.gov (United States)

Kikuchi, Mitsuru; Shitamichi, Kiyomi; Yoshimura, Yuko; Ueno, Sanae; Remijn, Gerard B; Hirosawa, Tetsu; Munesue, Toshio; Tsubokawa, Tsunehisa; Haruta, Yasuhiro; Oi, Manabu; Higashida, Haruhiro; Minabe, Yoshio

2011-10-19

Recent neuroimaging studies support the view that a left-lateralized brain network is crucial for language development in children. However, no previous studies have demonstrated a clear link between lateralized brain functional network and language performance in preschool children. Magnetoencephalography (MEG) is a noninvasive brain imaging technique and is a practical neuroimaging method for use in young children. MEG produces a reference-free signal, and is therefore an ideal tool to compute coherence between two distant cortical rhythms. In the present study, using a custom child-sized MEG system, we investigated brain networks while 78 right-handed preschool human children (32-64 months; 96% were 3-4 years old) listened to stories with moving images. The results indicated that left dominance of parietotemporal coherence in theta band activity (6-8 Hz) was specifically correlated with higher performance of language-related tasks, whereas this laterality was not correlated with nonverbal cognitive performance, chronological age, or head circumference. Power analyses did not reveal any specific frequencies that contributed to higher language performance. Our results suggest that it is not the left dominance in theta oscillation per se, but the left-dominant phase-locked connectivity via theta oscillation that contributes to the development of language ability in young children.

Sterol synthesis. A novel reductive rearrangement of an alpha,beta-unsaturated steroidal epoxide; a new chemical synthesis of 5alpha-cholest-8(14)-en-3beta, 15alpha-diol.

Science.gov (United States)

Parish, E J; Schroepfer, G J

1977-04-01

Reduction of 3beta-benzoyloxy-14alpha,15alpha-epoxy-5alpha-cholest-7-ene with either lithium triethylboro-hydride or lithium aluminum hydride (4 molar excess) gave 5-alpha-cholest-8(14)-en-3beta,15alpha-diol in high yield. Reduction of the epoxy ester with lithium triethylborodeuteride or lithium aluminum deuteride (4 molar excess) gave [7alpha-2-H]-5alpha-cholest-8(14)-en-3beta,15alpha-diol. Reduction of 2beta-benzoyloxy-14alpha,15alpha-epoxy-5alpha-cholest-7-ene with a large excess (24 molar excess) of lithium aluminum hydride gave, in addition to the expected 5alpha-cholest-8(14)-en-3beta,15alpha-diol, a significant yield (33%) of 5alpha-cholest-8(14)-en-3beta-o1. Reduction of the epoxy ester with a large excess (24 molar excess) of lithium aluminum deuteride gave [7alpha-2H]-5alpha-cholest-8(14)-en-3beta,15alpha-diol and 5alpha-cholest-8(14)-en-3beta-o1 which contained two atoms of stably bound deuterium.

Research on the reactions {sup 9}Be ({sup 3}He, 3 {alpha}) and {sup 10}B (d, 3 {alpha}); Contribution a l'etude experimentale des reactions {sup 9}Be ({sup 3}He, 3 {alpha}) et {sup 10}B (d, 3 {alpha})

Energy Technology Data Exchange (ETDEWEB)

Thouvenin, P [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1967-06-15

For studying these reactions, the detection of the final particles emitted in coincidence in the directions {theta}{sub 1} and {theta}{sub 2}, together with the bi-parametric analysis of the corresponding pulses are used. This method enables us to obtain the orthogonal Dalitz diagrams (E{sub 1}, E{sub 2}). An examination of the spectra obtained shows that the sequential mechanism appears to predominate. The contribution of the purely statistical process is less than 15 per cent of the total spectrum. In the case of {sup 10}B (d, 3 {alpha}), for E{sub d} = 1.5 MeV, 2,66 MeV and 3 MeV, the width of the peak of the first particles emitted, with respect to {sup 8}Be excitations close to 11 MeV, is found to be equal to 2.6 {+-} 0.6 MeV, much less than the width of the 2. excited state observed by {alpha} - {alpha} scattering. The coincidence spectra and the free spectra give an excitation energy of E{sub x} = 2.68 {+-} 0.07 MeV for the first excited state of {sup 8}Be. Some remarks are made concerning the anomalies observed for E{sub d} = 5 MeV and 9 MeV. The excited levels of {sup 8}Be at 13.91 MeV and 7.56 MeV which have been described in the past are not observed. (author) [French] La detection de deux des particules finales emises en cofncidence dans les directions {theta}{sub 1} et {theta}{sub 2}, et l'analyse biparametrique des impulsions correspondantes sont utilisees pour etudier ces reactions. Cette methode nous permet d'obtenir des diagrammes de Dalitz orthogonaux (E{sub 1}, E{sub 2}). L'examen des spectres obtenus montre que le mecanisme sequentiel semble predominant. La contribution du processus purement statistique est inferieure a 15 pour cent du spectre total. Dans le cas de {sup 10}B (d, 3 {alpha}), pour E{sub d} = 1,5 MeV, 2,66 MeV et 3 MeV, la largeur du pic des premieres particules emises relatives a des excitations de {sup 8}Be voisines de 11 MeV, est trouvee egale a 2,6 {+-} 0,6 MeV, tres inferieure a la largeur du 2. etat excite observee a l

NASA Rat Acoustic Tolerance Test 1994-1995: 8 kHz, 16 kHz, 32 kHz Experiments

Science.gov (United States)

Mele, Gary D.; Holley, Daniel C.; Naidu, Sujata

1996-01-01

Adult male Sprague-Dawley rats were exposed to chronic applied sound (74 to 79 dB, SPL) with octave band center frequencies of either 8, 16 or 32 kHz for up to 60 days. Control cages had ambient sound levels of about 62 dB (SPL). Groups of rats (test vs. control; N=9 per group) were euthanized after 0. 5. 14, 30, and 60 days. On each euthanasia day, objective evaluation of their physiology and behavior was performed using a Stress Assessment Battery (SAB) of measures. In addition, rat hearing was assessed using the brain stem auditory evoked potential (BAER) method after 60 days of exposure. No statistically significant differences in mean daily food use could be attributed to the presence of the applied test sound. Test rats used 5% more water than control rats. In the 8 kHz and 32 kHz tests this amount was statistically significant(P less than .05). This is a minor difference of questionable physiological significance. However, it may be an indication of a small reaction to the constant applied sound. Across all test frequencies, day 5 test rats had 6% larger spleens than control rats. No other body or organ weight differences were found to be statistically significant with respect to the application of sound. This spleen effect may be a transient adaptive process related to adaptation to the constant applied noise. No significant test effect on differential white blood cell counts could be demonstrated. One group demonstrated a low eosinophil count (16 kHz experiment, day 14 test group). However this was highly suspect. Across all test frequencies studied, day 5 test rats had 17% fewer total leukocytes than day 5 control rats. Sound exposed test rats exhibited 44% lower plasma corticosterone concentrations than did control rats. Note that the plasma corticosterone concentration was lower in the sound exposed test animals than the control animals in every instance (frequency exposure and number of days exposed).

Role of Frontal Alpha Oscillations in Creativity

Science.gov (United States)

Lustenberger, Caroline; Boyle, Michael R.; Foulser, A. Alban; Mellin, Juliann M.; Fröhlich, Flavio

2015-01-01

Creativity, the ability to produce innovative ideas, is a key higher-order cognitive function that is poorly understood. At the level of macroscopic cortical network dynamics, recent EEG data suggests that cortical oscillations in the alpha frequency band (8 – 12 Hz) are correlated with creative thinking. However, whether alpha oscillations play a fundamental role in creativity has remained unknown. Here we show that creativity is increased by enhancing alpha power using 10 Hz transcranial alternating current stimulation (10Hz-tACS) of the frontal cortex. In a study of 20 healthy participants with a randomized, balanced cross-over design, we found a significant improvement of 7.4% in the Creativity Index measured by the Torrance Test of Creative Thinking, a comprehensive and most frequently used assay of creative potential and strengths. In a second similar study with 20 subjects, 40Hz-tACS was used in instead of 10Hz-tACS to rule out a general “electrical stimulation” effect. No significant change in the Creativity Index was found for such frontal gamma stimulation. Our results suggest that alpha activity in frontal brain areas is selectively involved in creativity; this enhancement represents the first demonstration of specific neuronal dynamics that drive creativity and can be modulated by non-invasive brain stimulation. Our findings agree with the model that alpha recruitment increases with internal processing demands and is involved in inhibitory top-down control, which is an important requirement for creative ideation. PMID:25913062

Correlations between the alpha particles and ejectiles in the 208 MeV 14N on 93Nb reaction at three different ejectile angles

International Nuclear Information System (INIS)

Fukuda, T.; Ishihara, M.; Tanaka, M.; Ogata, H.; Miura, I.; Inoue, M.; Shimoda, T.; Katori, K.; Nakayama, S.

1983-01-01

The in plane correlations between alpha particles and various ejectiles were investigated in the reaction of 208 MeV 14 N on 93 Nb at theta/sub HI/ = +22 0 , +50 0 , and +80 0 . There were three sources of coincident alpha particles: (i) the sequential alpha decay of the excited ejectiles, (ii) the equilibrium alpha emission from the targetlike fragments, and (iii) the nonequilibrium process. Process (i) contributed mainly to the cross sections with the angular range of theta/sub α/ close to theta/sub HI/. Process (ii) contributed to the lowest part of the alpha energy spectra irrespectively of theta/sub HI/ and theta/sub α/. The remaining part was ascribed to process (iii). For this process the differential coincidence cross section of the lower energy part of the alpha particles was approximately factorized as d 4 sigma/dΩ/sub HI/dΩ/sub α/dE/sub HI/dE/sub α/ = K (d 2 sigma/dΩ/sub HI/dE/sub HI/)/sub singles/ (d 2 sigma/dΩ/sub α/dE/sub α/)/sub singles/ with Kapprox.0.4/b, whereas the higher energy part of the alpha particles emitted at the forward angles had a tendency to coincide weakly with the ejectiles emitted at the backward angles (theta/sub HI/ = +50 0 and +80 0 ) as compared to the lower energy part of the alpha particles

Frequency specific patterns of resting-state networks development from childhood to adolescence: A magnetoencephalography study.

Science.gov (United States)

Meng, Lu; Xiang, Jing

2016-11-01

The present study investigated frequency dependent developmental patterns of the brain resting-state networks from childhood to adolescence. Magnetoencephalography (MEG) data were recorded from 20 healthy subjects at resting-state with eyes-open. The resting-state networks (RSNs) was analyzed at source-level. Brain network organization was characterized by mean clustering coefficient and average path length. The correlations between brain network measures and subjects' age during development from childhood to adolescence were statistically analyzed in delta (1-4Hz), theta (4-8Hz), alpha (8-12Hz), and beta (12-30Hz) frequency bands. A significant positive correlation between functional connectivity with age was found in alpha and beta frequency bands. A significant negative correlation between average path lengths with age was found in beta frequency band. The results suggest that there are significant developmental changes of resting-state networks from childhood to adolescence, which matures from a lattice network to a small-world network. Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Concentration and mindfulness meditations: unique forms of consciousness?

Science.gov (United States)

Dunn, B R; Hartigan, J A; Mikulas, W L

1999-09-01

Electroencephalographic (EEG) recordings from 19 scalp recording sites were used to differentiate among two posited unique forms of mediation, concentration and mindfulness, and a normal relaxation control condition. Analyzes of all traditional frequency bandwidth data (i.e., delta 1-3 Hz; theta, 4-7 Hz; alpha, 8-12 Hz; beta 1, 13-25 Hz; beta 2, 26-32 Hz) showed strong mean amplitude frequency differences between the two meditation conditions and relaxation over numerous cortical sites. Furthermore, significant differences were obtained between concentration and mindfulness states at all bandwidths. Taken together, our results suggest that concentration and mindfulness "meditations" may be unique forms of consciousness and are not merely degrees of a state of relaxation.

Effect of 30 Hz Theta Burst Transcranial Magnetic Stimulation on the Primary Motor Cortex in Children and Adolescents

Directory of Open Access Journals (Sweden)

Ernest ePedapati

2015-02-01

Full Text Available Fourteen healthy children (13.8±2.2 years, range 10 to 16; M:F=5:9 received 30 Hz intermittent theta burst transcranial magnetic stimulation (iTBS with a stimulation intensity of 70% of resting motor threshold (RMT with a total of 300 (iTBS300 pulses. All volunteers were free of neurologic, psychiatric and serious medical illnesses, not taking any neuropsychiatric medications, and did not have any contraindications to Transcranial Magnetic Stimulation. Changes in the mean amplitudes of motor-evoked potentials from baseline following iTBS were expressed as a ratio and assessed from 1 to 10 minutes (BLOCK1 and 1 to 30 minutes (BLOCK2 using repeated-measures analysis of variance. All 14 subjects completed iTBS300 over the dominant primary motor cortex (M1 without any clinically reported adverse events. ITBS300 produced significant M1 facilitation (F5,65=3.165, p=0.01 at BLOCK1 and trend level M1 facilitation at BLOCK2 (F10,129=1.69, p=0.089. Although iTBS300 (stimulation duration of 92 seconds at 70% RMT delivered over M1 in typically developed children was well-tolerated and produced on average significant facilitatory changes in cortical excitability, the post-iTBS300 neurophysiologic response was variable in our small sample. ITBS300-induced changes may represent a potential neuroplastic biomarker in healthy children and those with neuro-genetic or neuro-psychiatric disorders. However, a larger sample size is needed to address safety and concerns of response variability.

Effect of 30 Hz theta burst transcranial magnetic stimulation on the primary motor cortex in children and adolescents

Science.gov (United States)

Pedapati, Ernest V.; Gilbert, Donald L.; Horn, Paul S.; Huddleston, David A.; Laue, Cameron S.; Shahana, Nasrin; Wu, Steve W.

2015-01-01

Fourteen healthy children (13.8 ± 2.2 years, range 10–16; M:F = 5:9) received 30 Hz intermittent theta burst transcranial magnetic stimulation (iTBS) with a stimulation intensity of 70% of resting motor threshold (RMT) with a total of 300 (iTBS300) pulses. All volunteers were free of neurologic, psychiatric and serious medical illnesses, not taking any neuropsychiatric medications, and did not have any contraindications to transcranial magnetic stimulation. Changes in the mean amplitudes of motor-evoked potentials from baseline following iTBS were expressed as a ratio and assessed from 1 to 10 min (BLOCK1) and 1–30 min (BLOCK2) using repeated-measures analysis of variance. All 14 subjects completed iTBS300 over the dominant primary motor cortex (M1) without any clinically reported adverse events. ITBS300 produced significant M1 facilitation [F(5, 65) = 3.165, p = 0.01] at BLOCK1 and trend level M1 facilitation at BLOCK2 [F(10, 129) = 1.69, p = 0.089]. Although iTBS300 (stimulation duration of 92 s at 70% RMT) delivered over M1 in typically developed children was well-tolerated and produced on average significant facilitatory changes in cortical excitability, the post-iTBS300 neurophysiologic response was variable in our small sample. ITBS300-induced changes may represent a potential neuroplastic biomarker in healthy children and those with neuro-genetic or neuro-psychiatric disorders. However, a larger sample size is needed to address safety and concerns of response variability. PMID:25762919

Research on the reactions {sup 9}Be ({sup 3}He, 3 {alpha}) and {sup 10}B (d, 3 {alpha}); Contribution a l'etude experimentale des reactions {sup 9}Be ({sup 3}He, 3 {alpha}) et {sup 10}B (d, 3 {alpha})

Energy Technology Data Exchange (ETDEWEB)

Thouvenin, P. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1967-06-15

For studying these reactions, the detection of the final particles emitted in coincidence in the directions {theta}{sub 1} and {theta}{sub 2}, together with the bi-parametric analysis of the corresponding pulses are used. This method enables us to obtain the orthogonal Dalitz diagrams (E{sub 1}, E{sub 2}). An examination of the spectra obtained shows that the sequential mechanism appears to predominate. The contribution of the purely statistical process is less than 15 per cent of the total spectrum. In the case of {sup 10}B (d, 3 {alpha}), for E{sub d} = 1.5 MeV, 2,66 MeV and 3 MeV, the width of the peak of the first particles emitted, with respect to {sup 8}Be excitations close to 11 MeV, is found to be equal to 2.6 {+-} 0.6 MeV, much less than the width of the 2. excited state observed by {alpha} - {alpha} scattering. The coincidence spectra and the free spectra give an excitation energy of E{sub x} = 2.68 {+-} 0.07 MeV for the first excited state of {sup 8}Be. Some remarks are made concerning the anomalies observed for E{sub d} = 5 MeV and 9 MeV. The excited levels of {sup 8}Be at 13.91 MeV and 7.56 MeV which have been described in the past are not observed. (author) [French] La detection de deux des particules finales emises en cofncidence dans les directions {theta}{sub 1} et {theta}{sub 2}, et l'analyse biparametrique des impulsions correspondantes sont utilisees pour etudier ces reactions. Cette methode nous permet d'obtenir des diagrammes de Dalitz orthogonaux (E{sub 1}, E{sub 2}). L'examen des spectres obtenus montre que le mecanisme sequentiel semble predominant. La contribution du processus purement statistique est inferieure a 15 pour cent du spectre total. Dans le cas de {sup 10}B (d, 3 {alpha}), pour E{sub d} = 1,5 MeV, 2,66 MeV et 3 MeV, la largeur du pic des premieres particules emises relatives a des excitations de {sup 8}Be voisines de 11 MeV, est trouvee egale a 2,6 {+-} 0,6 MeV, tres inferieure a la largeur du 2. etat excite

EEG theta and gamma responses to semantic violations in online sentence processing

NARCIS (Netherlands)

Hald, L.A.; Bastiaansen, M.C.M.; Hagoort, P.

2006-01-01

We explore the nature of the oscillatory dynamics in the EEG of subjects reading sentences that contain a semantic violation. More specifically, we examine whether increases in theta (≈3–7 Hz) and gamma (around 40 Hz) band power occur in response to sentences that were either semantically correct or

Fluctuating inhibitory inputs promote reliable spiking at theta frequencies in hippocampal interneurons

Directory of Open Access Journals (Sweden)

Duluxan eSritharan

2012-05-01

Full Text Available Theta frequency (4-12 Hz rhythms in the hippocampus play important roles in learning and memory. CA1 interneurons located at the stratum lacunosum-moleculare and radiatum junction (LM/RAD are thought to contribute to hippocampal theta population activities by rhythmically pacing pyramidal cells with inhibitory postsynaptic potentials. This implies that LM/RAD cells need to fire reliably at theta frequencies in vivo. To determine whether this could occur, we use biophysically-based LM/RAD model cells and apply different cholinergic and synaptic inputs to simulate in vivo-like network environments. We assess spike reliabilities and spiking frequencies, identifying biophysical properties and network conditions that best promote reliable theta spiking. We find that synaptic background activities that feature large inhibitory, but not excitatory, fluctuations are essential. This suggests that strong inhibitory input to these cells is vital for them to be able to contribute to population theta activities. Furthermore, we find that Type I-like oscillator models produced by augmented persistent sodium currents (INap or diminished A type potassium currents (IA enhance reliable spiking at lower theta frequencies. These Type I-like models are also the most responsive to large inhibitory fluctuations and can fire more reliably under such conditions. In previous work, we showed that INap and IA are largely responsible for establishing LM/RAD cells’ subthreshold activities. Taken together with this study, we see that while both these currents are important for subthreshold theta fluctuations and reliable theta spiking, they contribute in different ways – INap to reliable theta spiking and subthreshold activity generation, and IA to subthreshold activities at theta frequencies. This suggests that linking subthreshold and suprathreshold activities should be done with consideration of both in vivo contexts and biophysical specifics.

Different types of theta rhythmicity are induced by social and fearful stimuli in a network associated with social memory.

Science.gov (United States)

Tendler, Alex; Wagner, Shlomo

2015-02-16

Rhythmic activity in the theta range is thought to promote neuronal communication between brain regions. In this study, we performed chronic telemetric recordings in socially behaving rats to monitor electrophysiological activity in limbic brain regions linked to social behavior. Social encounters were associated with increased rhythmicity in the high theta range (7-10 Hz) that was proportional to the stimulus degree of novelty. This modulation of theta rhythmicity, which was specific for social stimuli, appeared to reflect a brain-state of social arousal. In contrast, the same network responded to a fearful stimulus by enhancement of rhythmicity in the low theta range (3-7 Hz). Moreover, theta rhythmicity showed different pattern of coherence between the distinct brain regions in response to social and fearful stimuli. We suggest that the two types of stimuli induce distinct arousal states that elicit different patterns of theta rhythmicity, which cause the same brain areas to communicate in different modes.

Functional role of frontal alpha oscillations in creativity.

Science.gov (United States)

Lustenberger, Caroline; Boyle, Michael R; Foulser, A Alban; Mellin, Juliann M; Fröhlich, Flavio

2015-06-01

Creativity, the ability to produce innovative ideas, is a key higher-order cognitive function that is poorly understood. At the level of macroscopic cortical network dynamics, recent electroencephalography (EEG) data suggests that cortical oscillations in the alpha frequency band (8-12 Hz) are correlated with creative thinking. However, whether alpha oscillations play a functional role in creativity has remained unknown. Here we show that creativity is increased by enhancing alpha power using 10 Hz transcranial alternating current stimulation (10 Hz-tACS) of the frontal cortex. In a study of 20 healthy participants with a randomized, balanced cross-over design, we found a significant improvement of 7.4% in the Creativity Index measured by the Torrance Test of Creative Thinking (TTCT), a comprehensive and most frequently used assay of creative potential and strengths. In a second similar study with 20 subjects, 40 Hz-tACS was used instead of 10 Hz-tACS to rule out a general "electrical stimulation" effect. No significant change in the Creativity Index was found for such frontal 40 Hz stimulation. Our results suggest that alpha activity in frontal brain areas is selectively involved in creativity; this enhancement represents the first demonstration of specific neuronal dynamics that drive creativity and can be modulated by non-invasive brain stimulation. Our findings agree with the model that alpha recruitment increases with internal processing demands and is involved in inhibitory top-down control, which is an important requirement for creative ideation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Resting-State Alpha in Autism Spectrum Disorder and Alpha Associations with Thalamic Volume

Science.gov (United States)

Edgar, J. Christopher; Heiken, Kory; Chen, Yu-Han; Herrington, John D.; Chow, Vivian; Liu, Song; Bloy, Luke; Huang, Mingxiong; Pandey, Juhi; Cannon, Katelyn M.; Qasmieh, Saba; Levy, Susan E.; Schultz, Robert T.; Roberts, Timothy P. L.

2015-01-01

Alpha circuits (8-12 Hz), necessary for basic and complex brain processes, are abnormal in autism spectrum disorder (ASD). The present study obtained estimates of resting-state (RS) alpha activity in children with ASD and examined associations between alpha activity, age, and clinical symptoms. Given that the thalamus modulates cortical RS alpha…

Theta vectors and quantum theta functions

International Nuclear Information System (INIS)

Chang-Young, Ee; Kim, Hoil

2005-01-01

In this paper, we clarify the relation between Manin's quantum theta function and Schwarz's theta vector. We do this in comparison with the relation between the kq representation, which is equivalent to the classical theta function, and the corresponding coordinate space wavefunction. We first explain the equivalence relation between the classical theta function and the kq representation in which the translation operators of the phase space are commuting. When the translation operators of the phase space are not commuting, then the kq representation is no longer meaningful. We explain why Manin's quantum theta function, obtained via algebra (quantum torus) valued inner product of the theta vector, is a natural choice for the quantum version of the classical theta function. We then show that this approach holds for a more general theta vector containing an extra linear term in the exponent obtained from a holomorphic connection of constant curvature than the simple Gaussian one used in Manin's construction

Age-related changes of frontal-midline theta is predictive of efficient memory maintenance.

Science.gov (United States)

Kardos, Z; Tóth, B; Boha, R; File, B; Molnár, M

2014-07-25

Frontal areas are thought to be the coordinators of working memory processes by controlling other brain areas reflected by oscillatory activities like frontal-midline theta (4-7 Hz). With aging substantial changes can be observed in the frontal brain areas, presumably leading to age-associated changes in cortical correlates of cognitive functioning. The present study aimed to test whether altered frontal-midline theta dynamics during working memory maintenance may underlie the capacity deficits observed in older adults. 33-channel EEG was recorded in young (18-26 years, N=20) and old (60-71 years, N=16) adults during the retention period of a visual delayed match-to-sample task, in which they had to maintain arrays of 3 or 5 colored squares. An additional visual odd-ball task was used to be able to measure the electrophysiological indices of sustained attentional processes. Old participants showed reduced frontal theta activity during both tasks compared to the young group. In the young memory maintenance-related frontal-midline theta activity was shown to be sensitive both to the increased memory demands and to efficient subsequent memory performance, whereas the old adults showed no such task-related difference in the frontal theta activity. The decrease of frontal-midline theta activity in the old group indicates that cerebral aging may alter the cortical circuitries of theta dynamics, thereby leading to age-associated decline of working memory maintenance function. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

Immediate effects of Alpha/theta and Sensory-Motor Rhythm feedback on music performance.

Science.gov (United States)

Gruzelier, J H; Hirst, L; Holmes, P; Leach, J

2014-07-01

This is one of a series of investigations comparing two EEG-neurofeedback protocols - Alpha/theta (A/T) and Sensory-Motor Rhythm (SMR) - for performance enhancement in the Arts, here with the focus on music. The original report (Egner and Gruzelier, 2003) established a beneficial outcome for elite conservatoire musicians following A/T training in two investigations. Subsequently this A/T advantage was replicated for both advanced instrumental and novice singing abilities, including improvisation, while SMR training benefited novice performance only (Gruzelier, Holmes et al., 2014). Here we report a replication of the latter study in university instrumentalists who as before were novice singers with one design change - post-training performances were conducted within the tenth final session instead of on a subsequent occasion. As before expert judges rated the domains of Creativity/Musicality, Communication/Presentation and Technique. The proximity to training of the music performances within the last session likely compromised gains from A/T learning, but perhaps reinforced the impact of SMR training efficacy. In support of validation there was evidence of strong within- and across-session A/T learning and positive linear trends for across-session SMR/theta and SMR/beta-2 ratio learning. In support of mediation learning correlated with music performance. The A/T outcome was markedly discrepant from previous studies and should dispel any impression that the hypnogogic state itself is transferred to the performance context. The effects of SMR ratio training are consistent with an impact on lower-order abilities required in novice performance such as sustained attention and memory, and benefiting all three domains of music assessment. Copyright © 2014 Elsevier B.V. All rights reserved.

EEG-neurofeedback training of beta band (12-22Hz) affects alpha and beta frequencies - A controlled study of a healthy population.

Science.gov (United States)

Jurewicz, Katarzyna; Paluch, Katarzyna; Kublik, Ewa; Rogala, Jacek; Mikicin, Mirosław; Wróbel, Andrzej

2018-01-08

The frequency-function relation of various EEG bands has inspired EEG-neurofeedback procedures intending to improve cognitive abilities in numerous clinical groups. In this study, we administered EEG-neurofeedback (EEG-NFB) to a healthy population to determine the efficacy of this procedure. We evaluated feedback manipulation in the beta band (12-22Hz), known to be involved in visual attention processing. Two groups of healthy adults were trained to either up- or down-regulate beta band activity, thus providing mutual control. Up-regulation training induced increases in beta and alpha band (8-12Hz) amplitudes during the first three sessions. Group-independent increases in the activity of both bands were observed in the later phase of training. EEG changes were not matched by measured behavioural indices of attention. Parallel changes in the two bands challenge the idea of frequency-specific EEG-NFB protocols and suggest their interdependence. Our study exposes the possibility (i) that the alpha band is more prone to manipulation, and (ii) that changes in the bands' amplitudes are independent from specified training. We therefore encourage a more comprehensive approach to EEG-neurofeedback training embracing physiological and/or operational relations among various EEG bands. Copyright © 2017 Elsevier Ltd. All rights reserved.

Theta dynamics in rat: speed and acceleration across the Septotemporal axis.

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Lauren L Long

Full Text Available Theta (6-12 Hz rhythmicity in the local field potential (LFP reflects a clocking mechanism that brings physically isolated neurons together in time, allowing for the integration and segregation of distributed cell assemblies. Variation in the theta signal has been linked to locomotor speed, sensorimotor integration as well as cognitive processing. Previously, we have characterized the relationship between locomotor speed and theta power and how that relationship varies across the septotemporal (long axis of the hippocampus (HPC. The current study investigated the relationship between whole body acceleration, deceleration and theta indices at CA1 and dentate gyrus (DG sites along the septotemporal axis of the HPC in rats. Results indicate that whole body acceleration and deceleration predicts a significant amount of variability in the theta signal beyond variation in locomotor speed. Furthermore, deceleration was more predictive of variation in theta amplitude as compared to acceleration as rats traversed a linear track. Such findings highlight key variables that systematically predict the variability in the theta signal across the long axis of the HPC. A better understanding of the relative contribution of these quantifiable variables and their variation as a function of experience and environmental conditions should facilitate our understanding of the relationship between theta and sensorimotor/cognitive functions.

Compact 4-kHz XeF-laser with multisectional discharge gap

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Andramanov, A. V.; Kabaev, S. A.; Lazhintsev, Boris V.; Nor-Arevyan, Vladimir A.; Selemir, V. D.

2005-03-01

An electric-discharge XeF-laser with a pulse repetition rate up to 4 kHz was developed. The laser electrode unit was made on the basis of plate-like electrodes with inductive-capacity discharge stabilization. The narrow discharge width laser energy was 3 mJ by using He/Xe/NF3 and Ne/Xe/NF3 mixtures at the total pressure of 0.8 atm and 1.2 atm, respectively. The maximum laser efficiency was ~ 0.73% The gas flow was formed with the help of a diametrical fan rotated by the direct-current motor with 80 W power. The gas velocity of 20 m/s in the interelectrode gap was achieved. The laser pulse energy for a pulse repetition rate up to 3.5...4 kHz was virtually equal to the laser pulse energy in the infrequently-repeating-pulse regime. The average output power of 12 W at the pulse repetition rate of 4 kHz was achieved. The relative root-mean-square pulse-to-pulse variation of the output energy σ = 2.5% was reached.

Recombinant human growth-regulated oncogene-alpha induces T lymphocyte chemotaxis. A process regulated via IL-8 receptors by IFN-gamma, TNF-alpha, IL-4, IL-10, and IL-13

DEFF Research Database (Denmark)

Jinquan, T; Frydenberg, Jane; Mukaida, N

1995-01-01

receptors on the cells. This process can be augmented by IFN-gamma and TNF-alpha, and inhibited by IL-4, IL-10, and IL-13. In addition, we also document that on T lymphocytes there exist IL-8 receptors that can be up-regulated by IFN-gamma, TNF-alpha, and IL-2. Our results demonstrate that rhGRO-alpha gene...

Alpha/Theta Neurofeedback Increases Mentalization and Default Mode Network Connectivity in a Non-Clinical Sample.

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Imperatori, Claudio; Della Marca, Giacomo; Amoroso, Noemi; Maestoso, Giulia; Valenti, Enrico Maria; Massullo, Chiara; Carbone, Giuseppe Alessio; Contardi, Anna; Farina, Benedetto

2017-11-01

Several studies showed the effectiveness of alpha/theta (A/T) neurofeedback training in treating some psychiatric conditions. Despite the evidence of A/T effectiveness, the psychological and neurobiological bases of its effects is still unclear. The aim of the present study was to explore the usefulness of the A/T training in increasing mentalization in a non-clinical sample. The modifications of electroencephalographic (EEG) functional connectivity in Default Mode Network (DMN) associated with A/T training were also investigated. Forty-four subjects were enrolled in the study and randomly assigned to receive ten sessions of A/T training [neurofeedback group (NFG) = 22], or to act as controls [waiting list group (WLG) = 22]. All participants were administered the mentalization questionnaire (MZQ) and the Symptom Checklist-90-Revised (SCL-90-R). In the post training assessment, compared to WLG, NFG showed a significant increase of MZQ total scores (3.94 ± 0.73 vs. 3.53 ± 0.77; F 1;43 = 8.19; p = 0.007; d = 0.863). Furthermore, A/T training was also associated with a significant increase of EEG functional connectivity in several DMN brain areas (e.g. Posterior Cingulate Cortex). Taken together our results support the usefulness of the A/T training in enhancing mentalization and DMN connectivity.

Synchronized brain activity during rehearsal and short-term memory disruption by irrelevant speech is affected by recall mode.

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Kopp, Franziska; Schröger, Erich; Lipka, Sigrid

2006-08-01

EEG coherence as a measure of synchronization of brain activity was used to investigate effects of irrelevant speech. In a delayed serial recall paradigm 21 healthy participants retained verbal items over a 10-s delay with and without interfering irrelevant speech. Recall after the delay was varied in two modes (spoken vs. written). Behavioral data showed the classic irrelevant speech effect and a superiority of written over spoken recall mode. Coherence, however, was more sensitive to processing characteristics and showed interactions between the irrelevant speech effect and recall mode during the rehearsal delay in theta (4-7.5 Hz), alpha (8-12 Hz), beta (13-20 Hz), and gamma (35-47 Hz) frequency bands. For gamma, a rehearsal-related decrease of the duration of high coherence due to presentation of irrelevant speech was found in a left-lateralized fronto-central and centro-temporal network only in spoken but not in written recall. In theta, coherence at predominantly fronto-parietal electrode combinations was indicative for memory demands and varied with individual working memory capacity assessed by digit span. Alpha coherence revealed similar results and patterns as theta coherence. In beta, a left-hemispheric network showed longer high synchronizations due to irrelevant speech only in written recall mode. EEG results suggest that mode of recall is critical for processing already during the retention period of a delayed serial recall task. Moreover, the finding that different networks are engaged with different recall modes shows that the disrupting effect of irrelevant speech is not a unitary mechanism.

Cognitive control during audiovisual working memory engages frontotemporal theta-band interactions.

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Daume, Jonathan; Graetz, Sebastian; Gruber, Thomas; Engel, Andreas K; Friese, Uwe

2017-10-03

Working memory (WM) maintenance of sensory information has been associated with enhanced cross-frequency coupling between the phase of low frequencies and the amplitude of high frequencies, particularly in medial temporal lobe (MTL) regions. It has been suggested that these WM maintenance processes are controlled by areas of the prefrontal cortex (PFC) via frontotemporal phase synchronisation in low frequency bands. Here, we investigated whether enhanced cognitive control during audiovisual WM as compared to visual WM alone is associated with increased low-frequency phase synchronisation between sensory areas maintaining WM content and areas from PFC. Using magnetoencephalography, we recorded neural oscillatory activity from healthy human participants engaged in an audiovisual delayed-match-to-sample task. We observed that regions from MTL, which showed enhanced theta-beta phase-amplitude coupling (PAC) during the WM delay window, exhibited stronger phase synchronisation within the theta-band (4-7 Hz) to areas from lateral PFC during audiovisual WM as compared to visual WM alone. Moreover, MTL areas also showed enhanced phase synchronisation to temporooccipital areas in the beta-band (20-32 Hz). Our results provide further evidence that a combination of long-range phase synchronisation and local PAC might constitute a mechanism for neuronal communication between distant brain regions and across frequencies during WM maintenance.

Frontal theta and beta synchronizations for monetary reward increase visual working memory capacity.

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Kawasaki, Masahiro; Yamaguchi, Yoko

2013-06-01

Visual working memory (VWM) capacity is affected by motivational influences; however, little is known about how reward-related brain activities facilitate the VWM systems. To investigate the dynamic relationship between VWM- and reward-related brain activities, we conducted time-frequency analyses using electroencephalograph (EEG) data obtained during a monetary-incentive delayed-response task that required participants to memorize the position of colored disks. In case of a correct answer, participants received a monetary reward (0, 10 or 50 Japanese yen) announced at the beginning of each trial. Behavioral results showed that VWM capacity under high-reward condition significantly increased compared with that under low- or no-reward condition. EEG results showed that frontal theta (6 Hz) amplitudes enhanced during delay periods and positively correlated with VWM capacity, indicating involvement of theta local synchronizations in VWM. Moreover, frontal beta activities (24 Hz) were identified as reward-related activities, because delay-period amplitudes correlated with increases in VWM capacity between high-reward and no-reward conditions. Interestingly, cross-frequency couplings between frontal theta and beta phases were observed only under high-reward conditions. These findings suggest that the functional dynamic linking between VWM-related theta and reward-related beta activities on the frontal regions plays an integral role in facilitating increases in VWM capacity.

Distinguishing stimulus and response codes in theta oscillations in prefrontal areas during inhibitory control of automated responses.

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Mückschel, Moritz; Dippel, Gabriel; Beste, Christian

2017-11-01

Response inhibition mechanisms are mediated via cortical and subcortical networks. At the cortical level, the superior frontal gyrus, including the supplementary motor area (SMA) and inferior frontal areas, is important. There is an ongoing debate about the functional roles of these structures during response inhibition as it is unclear whether these structures process different codes or contents of information during response inhibition. In the current study, we examined this question with a focus on theta frequency oscillations during response inhibition processes. We used a standard Go/Nogo task in a sample of human participants and combined different EEG signal decomposition methods with EEG beamforming approaches. The results suggest that stimulus coding during inhibitory control is attained by oscillations in the upper theta frequency band (∼7 Hz). In contrast, response selection codes during inhibitory control appear to be attained by the lower theta frequency band (∼4 Hz). Importantly, these different codes seem to be processed in distinct functional neuroanatomical structures. Although the SMA may process stimulus codes and response selection codes, the inferior frontal cortex may selectively process response selection codes during inhibitory control. Taken together, the results suggest that different entities within the functional neuroanatomical network associated with response inhibition mechanisms process different kinds of codes during inhibitory control. These codes seem to be reflected by different oscillations within the theta frequency band. Hum Brain Mapp 38:5681-5690, 2017. © 2017 Wiley-Liss, Inc. © 2017 Wiley Periodicals, Inc.

Neurofeedback training of EEG alpha rhythm enhances episodic and working memory.

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Hsueh, Jen-Jui; Chen, Tzu-Shan; Chen, Jia-Jin; Shaw, Fu-Zen

2016-07-01

Neurofeedback training (NFT) of the alpha rhythm has been used for several decades but is still controversial in regards to its trainability and effects on working memory. Alpha rhythm of the frontoparietal region are associated with either the intelligence or memory of healthy subjects and are also related to pathological states. In this study, alpha NFT effects on memory performances were explored. Fifty healthy participants were recruited and randomly assigned into a group receiving a 8-12-Hz amplitude (Alpha) or a group receiving a random 4-Hz amplitude from the range of 7 to 20 Hz (Ctrl). Three NFT sessions per week were conducted for 4 weeks. Working memory was assessed by both a backward digit span task and an operation span task, and episodic memory was assessed using a word pair task. Four questionnaires were used to assess anxiety, depression, insomnia, and cognitive function. The Ctrl group had no change in alpha amplitude and duration. In contrast, the Alpha group showed a progressive significant increase in the alpha amplitude and total alpha duration of the frontoparietal region. Accuracies of both working and episodic memories were significantly improved in a large proportion of participants of the Alpha group, particularly for those with remarkable alpha-amplitude increases. Scores of four questionnaires fell in a normal range before and after NFT. The current study provided supporting evidence for alpha trainability within a small session number compared with that of therapy. The findings suggested the enhancement of working and episodic memory through alpha NFT. Hum Brain Mapp 37:2662-2675, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Computational study of hippocampal-septal theta rhythm changes due to β-amyloid-altered ionic channels.

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Xin Zou

Full Text Available Electroencephagraphy (EEG of many dementia patients has been characterized by an increase in low frequency field potential oscillations. One of the characteristics of early stage Alzheimer's disease (AD is an increase in theta band power (4-7 Hz. However, the mechanism(s underlying the changes in theta oscillations are still unclear. To address this issue, we investigate the theta band power changes associated with β-Amyloid (Aβ peptide (one of the main markers of AD using a computational model, and by mediating the toxicity of hippocampal pyramidal neurons. We use an established biophysical hippocampal CA1-medial septum network model to evaluate four ionic channels in pyramidal neurons, which were demonstrated to be affected by Aβ. They are the L-type Ca²⁺ channel, delayed rectifying K⁺ channel, A-type fast-inactivating K⁺ channel and large-conductance Ca²⁺-activated K⁺ channel. Our simulation results demonstrate that only the Aβ inhibited A-type fast-inactivating K⁺ channel can induce an increase in hippocampo-septal theta band power, while the other channels do not affect theta rhythm. We further deduce that this increased theta band power is due to enhanced synchrony of the pyramidal neurons. Our research may elucidate potential biomarkers and therapeutics for AD. Further investigation will be helpful for better understanding of AD-induced theta rhythm abnormalities and associated cognitive deficits.

Frontal eye fields control attentional modulation of alpha and gamma oscillations in contralateral occipitoparietal cortex.

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Marshall, Tom R; O'Shea, Jacinta; Jensen, Ole; Bergmann, Til O

2015-01-28

Covertly directing visuospatial attention produces a frequency-specific modulation of neuronal oscillations in occipital and parietal cortices: anticipatory alpha (8-12 Hz) power decreases contralateral and increases ipsilateral to attention, whereas stimulus-induced gamma (>40 Hz) power is boosted contralaterally and attenuated ipsilaterally. These modulations must be under top-down control; however, the control mechanisms are not yet fully understood. Here we investigated the causal contribution of the human frontal eye field (FEF) by combining repetitive transcranial magnetic stimulation (TMS) with subsequent magnetoencephalography. Following inhibitory theta burst stimulation to the left FEF, right FEF, or vertex, participants performed a visual discrimination task requiring covert attention to either visual hemifield. Both left and right FEF TMS caused marked attenuation of alpha modulation in the occipitoparietal cortex. Notably, alpha modulation was consistently reduced in the hemisphere contralateral to stimulation, leaving the ipsilateral hemisphere relatively unaffected. Additionally, right FEF TMS enhanced gamma modulation in left visual cortex. Behaviorally, TMS caused a relative slowing of response times to targets contralateral to stimulation during the early task period. Our results suggest that left and right FEF are causally involved in the attentional top-down control of anticipatory alpha power in the contralateral visual system, whereas a right-hemispheric dominance seems to exist for control of stimulus-induced gamma power. These findings contrast the assumption of primarily intrahemispheric connectivity between FEF and parietal cortex, emphasizing the relevance of interhemispheric interactions. The contralaterality of effects may result from a transient functional reorganization of the dorsal attention network after inhibition of either FEF. Copyright © 2015 the authors 0270-6474/15/351638-10$15.00/0.

Neural rhythmic symphony of human walking observation: Upside-down and Uncoordinated condition on cortical theta, alpha, beta and gamma oscillations.

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David eZarka

2014-09-01

Full Text Available Biological motion observation has been recognized to produce dynamic change in sensorimotor activation according to the observed kinematics. Physical plausibility of the spatial-kinematic relationship of human movement may play a major role in the top-down processing of human motion recognition. Here, we investigated the time course of scalp activation during observation of human gait in order to extract and use it on future integrated brain-computer interface using virtual reality (VR. We analyzed event related potentials (ERP, the event related spectral perturbation (ERSP and the inter-trial coherence (ITC from high-density EEG recording during video display onset (-200 to 600 ms and the steady state visual evoked potentials (SSVEP inside the video of human walking 3D-animation in three conditions: Normal; Upside-down (inverted images; and Uncoordinated (pseudo-randomly mixed images. We found that early visual evoked response P120 was decreased in Upside-down condition. The N170 and P300b amplitudes were decreased in Uncoordinated condition. In Upside-down and Uncoordinated conditions, we found decreased alpha power and theta phase-locking. As regards gamma oscillation, power was increased during the Upside-down animation and decreased during the Uncoordinated animation. An SSVEP-like response oscillating at about 10 Hz was also described showing that the oscillating pattern is enhanced 300 ms after the heel strike event only in the Normal but not in the Upside-down condition. Our results are consistent with most of previous point-light display studies, further supporting possible use of virtual reality for neurofeedback applications.

Distinguishing rhythmic from non-rhythmic brain activity during rest in healthy neurocognitive aging.

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Caplan, Jeremy B; Bottomley, Monica; Kang, Pardeep; Dixon, Roger A

2015-05-15

Rhythmic brain activity at low frequencies (healthy neurocognitive aging are mixed. Here we address two reasons conventional spectral analyses may have led to inconsistent results. First, spectral-power measures are compared to a baseline condition; when resting activity is the signal of interest, it is unclear what the baseline should be. Second, conventional methods do not clearly differentiate power due to rhythmic versus non-rhythmic activity. The Better OSCillation detection method (BOSC; Caplan et al., 2001; Whitten et al., 2011) avoids these problems by using the signal's own spectral characteristics as a reference to detect elevations in power lasting a few cycles. We recorded electroencephalographic (EEG) signal during rest, alternating eyes open and closed, in healthy younger (18-25 years) and older (60-74 years) participants. Topographic plots suggested the conventional and BOSC analyses measured different sources of activity, particularly at frequencies, like delta (1-4Hz), at which rhythms are sporadic; topographies were more similar in the 8-12Hz alpha band. There was little theta-band activity meeting the BOSC method's criteria, suggesting prior findings of theta power in healthy aging may reflect non-rhythmic signal. In contrast, delta oscillations were present at higher levels than theta in both age groups. In summary, applying strict and standardized criteria for rhythmicity, slow rhythms appear present in the resting brain at delta and alpha, but not theta frequencies, and appear unchanged in healthy aging. Copyright © 2015 Elsevier Inc. All rights reserved.

Visual cortex responses reflect temporal structure of continuous quasi-rhythmic sensory stimulation.

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Keitel, Christian; Thut, Gregor; Gross, Joachim

2017-02-01

Neural processing of dynamic continuous visual input, and cognitive influences thereon, are frequently studied in paradigms employing strictly rhythmic stimulation. However, the temporal structure of natural stimuli is hardly ever fully rhythmic but possesses certain spectral bandwidths (e.g. lip movements in speech, gestures). Examining periodic brain responses elicited by strictly rhythmic stimulation might thus represent ideal, yet isolated cases. Here, we tested how the visual system reflects quasi-rhythmic stimulation with frequencies continuously varying within ranges of classical theta (4-7Hz), alpha (8-13Hz) and beta bands (14-20Hz) using EEG. Our findings substantiate a systematic and sustained neural phase-locking to stimulation in all three frequency ranges. Further, we found that allocation of spatial attention enhances EEG-stimulus locking to theta- and alpha-band stimulation. Our results bridge recent findings regarding phase locking ("entrainment") to quasi-rhythmic visual input and "frequency-tagging" experiments employing strictly rhythmic stimulation. We propose that sustained EEG-stimulus locking can be considered as a continuous neural signature of processing dynamic sensory input in early visual cortices. Accordingly, EEG-stimulus locking serves to trace the temporal evolution of rhythmic as well as quasi-rhythmic visual input and is subject to attentional bias. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Dataset of quantitative spectral EEG of different stages of kindling acquisition in rats.

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Jalilifar, Mostafa; Yadollahpour, Ali

2018-02-01

The data represented here are in relation with the manuscript "Quantitative assessments of extracellular EEG to classify specific features of main phases of seizure acquisition based on kindling model in Rat" (Jalilifar et al., 2017) [1] which quantitatively classified different main stages of the kindling process based on their electrophysiological characteristics using EEG signal processing. The data in the graphical form reported the contribution of different sub bands of EEG in different stages of kindling- induced epileptogenesis. Only EEG signals related to stages 1-2 (initial seizure stages (ISSs)), 3 (localized seizure stage (LSS)), and 4-5 (generalized seizure stages (GSSs) were transferred into frequency function by Fast Fourier Transform (FFT) and their power spectrum and power of each sub bands including delta (1-4 Hz), Theta (4-8 Hz), alpha (8-12 Hz), beta (12-28 Hz), gamma (28-40 Hz) were calculated with MATLAB 2013b. Accordingly, all results were obtained quantitatively which can contribute to reduce the errors in the behavioral assessments.

Pain and the alpha-sleep anomaly: a mechanism of sleep disruption in facioscapulohumeral muscular dystrophy.

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Della Marca, Giacomo; Frusciante, Roberto; Vollono, Catello; Iannaccone, Elisabetta; Dittoni, Serena; Losurdo, Anna; Testani, Elisa; Gnoni, Valentina; Colicchio, Salvatore; Di Blasi, Chiara; Erra, Carmen; Mazza, Salvatore; Ricci, Enzo

2013-04-01

To measure the presence of the alpha-sleep anomaly in facioscapulohumeral muscular dystrophy (FSHD) and to evaluate the association between the sleep electroencephalogram (EEG) pattern and the presence of musculoskeletal pain. Cross-sectional study. Sleep laboratory. Fifty-five consecutive adult FSHD patients, 26 women and 29 men, age 49.6 ± 15.1 years (range 18-76). Questionnaires and polysomnography. Patients were asked to indicate if in the 3 months before the sleep study they presented persisting or recurring musculoskeletal pain. Patients who reported pain were asked to fill in the Italian version of the Brief Pain Inventory and the McGill Pain questionnaire, and a 101-point visual analog scale (VAS) for pain intensity. Polysomnographic recordings were performed. EEG was analyzed by means of Fast Fourier Transform. Four power spectra bands (δ 0-4 Hz, θ 4-8 Hz, α 8-14 Hz, β 14-32 Hz) were computed. Sleep macrostructure parameters and alpha/delta EEG power ratio during non rapid eye movement (NREM) sleep were compared between patients with and without pain. Forty-two patients in our sample reported chronic pain. VAS mean score was 55.2 ± 23.8 (range 10-100), pain rating index score was 13.8 ± 10.2, and present pain intensity was 2.5 ± 0.8. The statistical analysis documented an increased occurrence of the alpha and beta rhythms during NREM sleep in FSHD patients with pain. Significant correlations were observed between the alpha/delta power ratio during NREM sleep and pain measures. Chronic musculoskeletal pain is frequent in FSHD patients, and it represents a major mechanism of sleep disruption. Wiley Periodicals, Inc.

EEG spectral analysis of attention in ADHD: implications for neurofeedback training?

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Hartmut eHeinrich

2014-08-01

Full Text Available Objective: In children with attention-deficit/hyperactivity disorder (ADHD, an increased theta/beta ratio in the resting EEG typically serves as a rationale to conduct theta/beta neurofeedback training. However, this finding is increasingly challenged. As neurofeedback may rather target an active than a passive state, we studied the EEG in a condition that requires attention.Methods: In children with ADHD of the DSM-IV combined type (ADHD-C; N=15 and of the predominantly inattentive type (ADHD-I; N=9 and in typically developing children (N=19, EEG spectral analysis was conducted for segments during the attention network test without processing of stimuli and overt behavior. Frontal (F3, Fz, F4, central (C3, Cz, C4 and parietal (P3, Pz, P4 electrodes were included in the statistical analysis. To investigate if EEG spectral parameters are related to performance measures, correlation coefficients were calculated.Results: Particularly in the ADHD-C group, higher theta and alpha activity was found with the most prominent effect in the upper-theta/lower-alpha (5.5-10.5 Hz range. In the ADHD-I group, a significantly higher theta/beta ratio was observed at single electrodes (F3, Fz and a tendency for a higher theta/beta ratio when considering all electrodes (large effect size. Higher 5.5-10.5 Hz activity was associated with higher reaction time variability with the effect most prominent in the ADHD-C group. A higher theta/beta ratio was associated with higher reaction times, particularly in the ADHD-I group.Conclusions: 1. In an attention demanding period, children with ADHD are characterized by an underactivated state in the EEG with subtype-specific differences. 2. The functional relevance of related EEG parameters is indicated by associations with performance (reaction time measures. 3. Findings provide a rationale for applying NF protocols targeting theta (and alpha activity and the theta/beta ratio in subgroups of children with ADHD.

Differential effects of ongoing EEG beta and theta power on memory formation.

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Scholz, Sebastian; Schneider, Signe Luisa; Rose, Michael

2017-01-01

Recently, elevated ongoing pre-stimulus beta power (13-17 Hz) at encoding has been associated with subsequent memory formation for visual stimulus material. It is unclear whether this activity is merely specific to visual processing or whether it reflects a state facilitating general memory formation, independent of stimulus modality. To answer that question, the present study investigated the relationship between neural pre-stimulus oscillations and verbal memory formation in different sensory modalities. For that purpose, a within-subject design was employed to explore differences between successful and failed memory formation in the visual and auditory modality. Furthermore, associative memory was addressed by presenting the stimuli in combination with background images. Results revealed that similar EEG activity in the low beta frequency range (13-17 Hz) is associated with subsequent memory success, independent of stimulus modality. Elevated power prior to stimulus onset differentiated successful from failed memory formation. In contrast, differential effects between modalities were found in the theta band (3-7 Hz), with an increased oscillatory activity before the onset of later remembered visually presented words. In addition, pre-stimulus theta power dissociated between successful and failed encoding of associated context, independent of the stimulus modality of the item itself. We therefore suggest that increased ongoing low beta activity reflects a memory promoting state, which is likely to be moderated by modality-independent attentional or inhibitory processes, whereas high ongoing theta power is suggested as an indicator of the enhanced binding of incoming interlinked information.

Discovery of decaHz flaring in SAX J1808.4-3658

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Bult P.

2014-01-01

Full Text Available We report on the discovery of strong decaHz flaring in the early decay of two out of five outbursts of the accreting millisecond X-ray pulsar SAX J1808.4-3658. The decaHz flaring switches on and, after ~3 days, off again, on a time scale of 1-2 hours. When the flaring is present, the total 0.05-10 Hz variability has a fractional rms amplitude of 20 to 30 percent, well in excess of the 8 to 12 percent rms broad-band noise usually seen in power spectra of SAX J1808 in this frequency range. Coherent 401 Hz pulsations are seen throughout the observations in which the decaHz flaring is detected. We find that the absolute amplitude of the pulsations varies with the flux modulation of the decaHz flaring, indicating that the flaring is caused by an accretion rate modulation already present in the accretion flow prior to matter entering the accretion funnel. We suggest that the decaHz flaring is the result of the Spruit-Taam instability [1]. This instability arises when the inner accretion disk approaches co-rotation. The rotation of the stellar magnetosphere then acts as a propeller, suppressing accretion onto the neutron star. A matter reservoir forms in the inner accretion disk, which episodically empties onto the neutron star, causing flares at a decaHz timescale. A similar explanation was proposed earlier for 1 Hz flaring occurring late in three of five outbursts, mutually exclusive with the decaHz flaring. The 1 Hz flaring was observed at luminosities a factor 5 to 10 below where we see the decaHz flaring. That a different branch of the Spruit-Taam instability could also act at the much higher luminosity levels of the decaHz flaring had recently been predicted by D’Angelo & Spruit [2, 3]. We discuss these findings in the context of the parameters of the Spruit-Taam-d’Angelo model of the instability. If confirmed, after millisecond pulsations, 1 Hz and decaHz flaring would be another diagnostic of the presence of a magnetosphere in accreting low

Impulse Control Disorders in Parkinson's Disease are Associated with Alterations in Reward-Related Cortical Oscillations.

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Carriere, Nicolas; Bourriez, Jean-Louis; Delval, Arnaud; Derambure, Philippe; Defebvre, Luc; Dujardin, Kathy

2016-06-28

Impulse control disorders (ICDs) in Parkinson's disease (PD) are related to treatment with dopamine agonists, which is thought to deregulate the dopaminergic mesolimbic pathway and impair reward evaluation. EEG studies in healthy controls (HCs) have suggested that the increase in theta power observed after negative outcome is a marker of reward processing. To compare outcome-locked, event-related spectral perturbation in a gambling task in PD patients with and without ICDs and in HCs. Twelve PD patients with ICDs, 12 PD patients without ICDs and 14 HCs underwent EEG while performing a gambling task. The groups were compared in terms of (i) the peak EEG power in the theta (4-7 Hz), alpha (8-14 Hz) and beta (15-30 Hz) frequency bands between 200 and 500 ms after the outcome, and (ii) time-frequency plots at Fz, FCz and Cz. Positive outcomes were associated with greater theta power than negative outcomes in patients without ICDs and in HCs, but not in patients with ICDs. Patients with ICDs and HCs displayed greater theta power following unexpectedly high outcomes. HCs displayed greater beta power following high amplitude than low amplitude outcomes, whereas patients with ICD showed the opposite pattern. In PD, ICDs are associated with (i) weaker modulation of frontocentral theta power by reward valence, (ii) greater frontocentral theta power following unexpected, high outcomes, and (iii) a reversal of the effect of risk on beta oscillations. These observations are consistent with an impairment in prediction error computation in the medial prefrontal cortex.

Verbal working memory-related neural network communication in schizophrenia.

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Kustermann, Thomas; Popov, Tzvetan; Miller, Gregory A; Rockstroh, Brigitte

2018-04-19

Impaired working memory (WM) in schizophrenia is associated with reduced hemodynamic and electromagnetic activity and altered network connectivity within and between memory-associated neural networks. The present study sought to determine whether schizophrenia involves disruption of a frontal-parietal network normally supporting WM and/or involvement of another brain network. Nineteen schizophrenia patients (SZ) and 19 healthy comparison subjects (HC) participated in a cued visual-verbal Sternberg task while dense-array EEG was recorded. A pair of item arrays each consisting of 2-4 consonants was presented bilaterally for 200 ms with a prior cue signaling the hemifield of the task-relevant WM set. A central probe letter 2,000 ms later prompted a choice reaction time decision about match/mismatch with the target WM set. Group and WM load effects on time domain and time-frequency domain 11-15 Hz alpha power were assessed for the cue-to-probe time window, and posterior 11-15 Hz alpha power and frontal 4-8 Hz theta power were assessed during the retention period. Directional connectivity was estimated via Granger causality, evaluating group differences in communication. SZ showed slower responding, lower accuracy, smaller overall time-domain alpha power increase, and less load-dependent alpha power increase. Midline frontal theta power increases did not vary by group or load. Network communication in SZ was characterized by temporal-to-posterior information flow, in contrast to bidirectional temporal-posterior communication in HC. Results indicate aberrant WM network activity supporting WM in SZ that might facilitate normal load-dependent and only marginally less accurate task performance, despite generally slower responding. © 2018 Society for Psychophysiological Research.

Analysis of EEG activity in response to binaural beats with different frequencies.

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Gao, Xiang; Cao, Hongbao; Ming, Dong; Qi, Hongzhi; Wang, Xuemin; Wang, Xiaolu; Chen, Runge; Zhou, Peng

2014-12-01

When two coherent sounds with nearly similar frequencies are presented to each ear respectively with stereo headphones, the brain integrates the two signals and produces a sensation of a third sound called binaural beat (BB). Although earlier studies showed that BB could influence behavior and cognition, common agreement on the mechanism of BB has not been reached yet. In this work, we employed Relative Power (RP), Phase Locking Value (PLV) and Cross-Mutual Information (CMI) to track EEG changes during BB stimulations. EEG signals were acquired from 13 healthy subjects. Five-minute BBs with four different frequencies were tested: delta band (1 Hz), theta band (5 Hz), alpha band (10 Hz) and beta band (20 Hz). We observed RP increase in theta and alpha bands and decrease in beta band during delta and alpha BB stimulations. RP decreased in beta band during theta BB, while RP decreased in theta band during beta BB. However, no clear brainwave entrainment effect was identified. Connectivity changes were detected following the variation of RP during BB stimulations. Our observation supports the hypothesis that BBs could affect functional brain connectivity, suggesting that the mechanism of BB-brain interaction is worth further study. Copyright © 2014. Published by Elsevier B.V.

Oscillatory neuronal dynamics associated with manual acupuncture: a magnetoencephalography study using beamforming analysis

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Aziz eAsghar

2012-11-01

Full Text Available Magnetoencephalography (MEG enables non-invasive recording of neuronal activity, with reconstruction methods providing estimates of underlying brain source locations and oscillatory dynamics from externally recorded neuromagnetic fields. The aim of our study was to use MEG to determine the effect of manual acupuncture on neuronal oscillatory dynamics. A major problem in MEG investigations of manual acupuncture is the absence of onset times for each needle manipulation. Given that beamforming (spatial filtering analysis is not dependent upon stimulus-driven responses being phase-locked to stimulus onset, we postulated that beamforming could reveal source locations and induced changes in neuronal activity during manual acupuncture. In a beamformer analysis, a two-minute period of manual acupuncture needle manipulation delivered to the ipsilateral right LI-4 (Hegu acupoint was contrasted with a two-minute baseline period. We considered oscillatory power changes in the theta (4-8Hz, alpha (8-13Hz, beta (13-30Hz and gamma (30-100Hz frequency bands. We found significant decreases in beta band power in the contralateral primary somatosensory cortex and superior frontal gyrus. In the ipsilateral cerebral hemisphere, we found significant power decreases in beta and gamma frequency bands in only the superior frontal gyrus. No significant power modulations were found in theta and alpha bands. Our results indicate that beamforming is a useful analytical tool to reconstruct underlying neuronal activity associated with manual acupuncture. Our main finding was of beta power decreases in primary somatosensory cortex and superior frontal gyrus, which opens up a line of future investigation regarding whether this contributes towards an underlying mechanism of acupuncture.

Slow oscillation electrical brain stimulation during waking promotes EEG theta activity and memory encoding

DEFF Research Database (Denmark)

Kirov, Roumen; Weiss, Carsten; Siebner, Hartwig R

2009-01-01

typically occurring during this state of sleep were also enhanced. Here, we show that the same tSOS applied in the waking brain also induced an increase in endogenous EEG slow oscillations (0.4-1.2 Hz), although in a topographically restricted fashion. Applied during wakefulness tSOS, additionally, resulted......The application of transcranial slow oscillation stimulation (tSOS; 0.75 Hz) was previously shown to enhance widespread endogenous EEG slow oscillatory activity when applied during a sleep period characterized by emerging endogenous slow oscillatory activity. Processes of memory consolidation...... induced by tSOS critically depend on brain state. In response to tSOS during wakefulness the brain transposes stimulation by responding preferentially with theta oscillations and facilitated encoding....

Effect of the theta-alpha-Al2O3 transformation on the oxidation behavior of beta-NiAl+Zr

Science.gov (United States)

Rybicki, George C.; Smialek, James L.

1989-01-01

Isothermal oxidation of NiAl+Zr has been performed over the temperature range of 800-1200 C and studied by TGA, XRD, and SEM. A discontinuous decrease in growth rate of two orders of magnitude was observed at 1000 C due to the formation of alpha-Al2O3 from theta-Al2O3. This transformation also resulted in a dramatic change in the surface morphology of the scales, as a whisker topography was changed into a weblike network of oxide ridges and radial transformation cracks. It is believed that the ridges are evidence for a short-circuit outward aluminum diffusion growth mechanism that has been documented in a number of O-18 tracer studies.

The Role of Oscillatory Phase in Determining the Temporal Organization of Perception: Evidence from Sensory Entrainment.

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Ronconi, Luca; Melcher, David

2017-11-01

Recent behavioral, neuroimaging, and neurophysiological studies have renewed the idea that the information processing within different temporal windows is linked to the phase and/or frequency of the ongoing oscillations, predominantly in the theta/alpha band (∼4-7 and 8-12 Hz, respectively). However, being correlational in nature, this evidence might reflect a nonfunctional byproduct rather than having a causal role. A more direct link can be shown with methods that manipulate oscillatory activity. Here, we used audiovisual entrainment at different frequencies in the prestimulus period of a temporal integration/segregation task. We hypothesized that entrainment would align ongoing oscillations and drive them toward the stimulation frequency. To reveal behavioral oscillations in temporal perception after the entrainment, we sampled the segregation/integration performance densely in time. In Experiment 1, two groups of human participants (both males and females) received stimulation either at the lower or the upper boundary of the alpha band (∼8.5 vs 11.5 Hz). For both entrainment frequencies, we found a phase alignment of the perceptual oscillation across subjects, but with two different power spectra that peaked near the entrainment frequency. These results were confirmed when perceptual oscillations were characterized in the time domain with sinusoidal fittings. In Experiment 2, we replicated the findings in a within-subject design, extending the results for frequencies in the theta (∼6.5 Hz), but not in the beta (∼15 Hz), range. Overall, these findings show that temporal segregation can be modified by sensory entrainment, providing evidence for a critical role of ongoing oscillations in the temporal organization of perception. SIGNIFICANCE STATEMENT The continuous flow of sensory input is not processed in an analog fashion, but rather is grouped by the perceptual system over time. Recent studies pinpointed the phase and/or frequency of the neural

Involvement of the subthalamic nucleus in impulse control disorders associated with Parkinson's disease.

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Rodriguez-Oroz, Maria C; López-Azcárate, Jon; Garcia-Garcia, David; Alegre, Manuel; Toledo, Jon; Valencia, Miguel; Guridi, Jorge; Artieda, Julio; Obeso, Jose A

2011-01-01

Behavioural abnormalities such as impulse control disorders may develop when patients with Parkinson's disease receive dopaminergic therapy, although they can be controlled by deep brain stimulation of the subthalamic nucleus. We have recorded local field potentials in the subthalamic nucleus of 28 patients with surgically implanted subthalamic electrodes. According to the predominant clinical features of each patient, their Parkinson's disease was associated with impulse control disorders (n = 10), dyskinesias (n = 9) or no dopaminergic mediated motor or behavioural complications (n = 9). Recordings were obtained during the OFF and ON dopaminergic states and the power spectrum of the subthalamic activity as well as the subthalamocortical coherence were analysed using Fourier transform-based techniques. The position of each electrode contact was determined in the postoperative magnetic resonance image to define the topography of the oscillatory activity recorded in each patient. In the OFF state, the three groups of patients had similar oscillatory activity. By contrast, in the ON state, the patients with impulse control disorders displayed theta-alpha (4-10 Hz) activity (mean peak: 6.71 Hz) that was generated 2-8 mm below the intercommissural line. Similarly, the patients with dyskinesia showed theta-alpha activity that peaked at a higher frequency (mean: 8.38 Hz) and was generated 0-2 mm below the intercommissural line. No such activity was detected in patients that displayed no dopaminergic side effects. Cortico-subthalamic coherence was more frequent in the impulsive patients in the 4-7.5 Hz range in scalp electrodes placed on the frontal regions anterior to the primary motor cortex, while in patients with dyskinesia it was in the 7.5-10 Hz range in the leads overlying the primary motor and supplementary motor area. Thus, dopaminergic side effects in Parkinson's disease are associated with oscillatory activity in the theta-alpha band, but at different

A Comparison of Frontal Theta Activity During Shooting among Biathletes and Cross-Country Skiers before and after Vigorous Exercise.

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Harri Luchsinger

Full Text Available Previous studies using electroencephalography (EEG to monitor brain activity have linked higher frontal theta activity to more focused attention and superior performance in goal-directed precision tasks. In biathlon, shooting performance requires focused attention after high-intensity cross-country skiing.To compare biathletes (serving as experts and cross-country skiers (novices and examine the effect of vigorous exercise on frontal theta activity during shooting.EEG frontal theta (4-7 Hz activity was compared between nine biathletes and eight cross-country skiers at comparable skiing performance levels who fired 100 shots on a 5-m indoor shooting range in quiescent condition followed by 20 shots after each of five 6-min high-intensity roller skiing sessions in the skating technique on a treadmill.Biathletes hit 80±14% and 81±10% before and after the roller skiing sessions, respectively. For the cross-country skiers these values were significantly lower than for the biathletes and amounted to 39±13% and 44±11% (p<0.01. Biathletes had on average 6% higher frontal theta activity during shooting as compared to cross-country skiers (F1,15 = 4.82, p = 0.044, but no significant effect of vigorous exercise on frontal theta activity in either of the two groups were found (F1,15 = 0.14, p = 0.72.Biathletes had significantly higher frontal theta activity than cross-country skiers during shooting, indicating higher focused attention in biathletes. Vigorous exercise did not decrease shooting performance or frontal theta activity during shooting in biathletes and cross-country skiers.

Differential effects of ongoing EEG beta and theta power on memory formation.

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Sebastian Scholz

Full Text Available Recently, elevated ongoing pre-stimulus beta power (13-17 Hz at encoding has been associated with subsequent memory formation for visual stimulus material. It is unclear whether this activity is merely specific to visual processing or whether it reflects a state facilitating general memory formation, independent of stimulus modality. To answer that question, the present study investigated the relationship between neural pre-stimulus oscillations and verbal memory formation in different sensory modalities. For that purpose, a within-subject design was employed to explore differences between successful and failed memory formation in the visual and auditory modality. Furthermore, associative memory was addressed by presenting the stimuli in combination with background images. Results revealed that similar EEG activity in the low beta frequency range (13-17 Hz is associated with subsequent memory success, independent of stimulus modality. Elevated power prior to stimulus onset differentiated successful from failed memory formation. In contrast, differential effects between modalities were found in the theta band (3-7 Hz, with an increased oscillatory activity before the onset of later remembered visually presented words. In addition, pre-stimulus theta power dissociated between successful and failed encoding of associated context, independent of the stimulus modality of the item itself. We therefore suggest that increased ongoing low beta activity reflects a memory promoting state, which is likely to be moderated by modality-independent attentional or inhibitory processes, whereas high ongoing theta power is suggested as an indicator of the enhanced binding of incoming interlinked information.

Portable wireless neurofeedback system of EEG alpha rhythm enhances memory.

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Wei, Ting-Ying; Chang, Da-Wei; Liu, You-De; Liu, Chen-Wei; Young, Chung-Ping; Liang, Sheng-Fu; Shaw, Fu-Zen

2017-11-13

Effect of neurofeedback training (NFT) on enhancement of cognitive function or amelioration of clinical symptoms is inconclusive. The trainability of brain rhythm using a neurofeedback system is uncertainty because various experimental designs are used in previous studies. The current study aimed to develop a portable wireless NFT system for alpha rhythm and to validate effect of the NFT system on memory with a sham-controlled group. The proposed system contained an EEG signal analysis device and a smartphone with wireless Bluetooth low-energy technology. Instantaneous 1-s EEG power and contiguous 5-min EEG power throughout the training were developed as feedback information. The training performance and its progression were kept to boost usability of our device. Participants were blinded and randomly assigned into either the control group receiving random 4-Hz power or Alpha group receiving 8-12-Hz power. Working memory and episodic memory were assessed by the backward digital span task and word-pair task, respectively. The portable neurofeedback system had advantages of a tiny size and long-term recording and demonstrated trainability of alpha rhythm in terms of significant increase of power and duration of 8-12 Hz. Moreover, accuracies of the backward digital span task and word-pair task showed significant enhancement in the Alpha group after training compared to the control group. Our tiny portable device demonstrated success trainability of alpha rhythm and enhanced two kinds of memories. The present study suggest that the portable neurofeedback system provides an alternative intervention for memory enhancement.

Photic driving in the electroencephalogram of children and adolescents: harmonic structure and relation to the resting state

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V.V. Lazarev

2001-12-01

Full Text Available In order to identify latent bioelectrical oscillators, 15 normal subjects (aged 9-17 years, 8 males, 7 females were subjected to intermittent photic stimulation. The EEG amplitude spectra corresponding to the 11 fixed frequencies of stimulation presented (3-24 Hz were combined to form "profiles" of the driving reaction in the right occipital area. The driving response varied with frequency, and was demonstrable in 70-100% of cases (using as criterion peak amplitudes 20% larger than those of the neighbors. The strongest responses were observed at the frequency closest to the alpha peak of the resting EEG. A secondary profile maximum was in the theta band. In 10 subjects, this maximum exceeded half the alpha peak (with an average of 72.4% of the alpha peak, while in the resting spectra, theta amplitudes were much lower than the alpha maxima. This responsiveness in theta activity seems to be characteristic of prepubertal and pubertal subjects. The profiles and resting EEG spectra showed a highly significant Pearson's correlation, with the peak in the theta band of the profiles being the main difference observed between them. The correlation coefficient was significantly correlated with the ratio of the maxima in the theta and alpha bands (R = -0.77, P<0.001. The correlation coefficient between profile and resting spectrum may be a useful indicator in screening methods used to reveal latent cerebral oscillators. Profiles for the second and third harmonics were correlated with those of the first harmonic (fundamental frequency, when considering the corresponding EEG frequencies. Peak frequencies in all three profiles were close to those of the individual's background alpha rhythm, and peak amplitudes in higher harmonics were not much lower than those of the fundamental frequency (mean values of 84 and 63%, for second and third harmonics, respectively.

Midfrontal Theta and Posterior Parietal Alpha Band Oscillations Support Conflict Resolution in a Masked Affective Priming Task.

Science.gov (United States)

Jiang, Jun; Bailey, Kira; Xiao, Xiao

2018-01-01

Past attempts to characterize the neural mechanisms of affective priming have conceptualized it in terms of classic cognitive conflict, but have not examined the neural oscillatory mechanisms of subliminal affective priming. Using behavioral and electroencephalogram (EEG) time frequency (TF) analysis, the current study examines the oscillatory dynamics of unconsciously triggered conflict in an emotional facial expressions version of the masked affective priming task. The results demonstrate that the power dynamics of conflict are characterized by increased midfrontal theta activity and suppressed parieto-occipital alpha activity. Across-subject and within-trial correlation analyses further confirmed this pattern. Phase synchrony and Granger causality analyses (GCAs) revealed that the fronto-parietal network was involved in unconscious conflict detection and resolution. Our findings support a response conflict account of affective priming, and reveal the role of the fronto-parietal network in unconscious conflict control.

Midfrontal Theta and Posterior Parietal Alpha Band Oscillations Support Conflict Resolution in a Masked Affective Priming Task

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Jun Jiang

2018-05-01

Full Text Available Past attempts to characterize the neural mechanisms of affective priming have conceptualized it in terms of classic cognitive conflict, but have not examined the neural oscillatory mechanisms of subliminal affective priming. Using behavioral and electroencephalogram (EEG time frequency (TF analysis, the current study examines the oscillatory dynamics of unconsciously triggered conflict in an emotional facial expressions version of the masked affective priming task. The results demonstrate that the power dynamics of conflict are characterized by increased midfrontal theta activity and suppressed parieto-occipital alpha activity. Across-subject and within-trial correlation analyses further confirmed this pattern. Phase synchrony and Granger causality analyses (GCAs revealed that the fronto-parietal network was involved in unconscious conflict detection and resolution. Our findings support a response conflict account of affective priming, and reveal the role of the fronto-parietal network in unconscious conflict control.

Study on EEG power and coherence in patients with mild cognitive impairment during working memory task

Institute of Scientific and Technical Information of China (English)

JIANG Zheng-yan

2005-01-01

To investigate the features of electroencephalography (EEG) power and coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). Thirty-five patients (17 males, 18 females; 52～71 years old) and 34 sex- and age-matched controls (17 males, 17 females; 51～63 years old) were recruited in the present study. Mini-Mental State Examination (MMSE) of 35 patients with MCI and 34 normal controls revealed that the scores of MCI patients did not differ significantly from those of normal controls (P＞0.05). Then, EEGs at rest and during working memory task with three levels of working memory load were recorded. The EEG power was computed over 10 channels: right and left frontal (F3, F4), central (C3,C4), parietal (P3, P4), temporal (TS, T6) and occipital (O1, O2); inter-hemispheric coherences were computed from five electrode pairs of F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 for delta (1.0～3.5 Hz), theta (4.0～7.5 Hz), alpha-1 (8.0～10.0 Hz), alpha-2 (10.5～13.0 Hz), beta-1 (13.5～18.0 Hz) and beta-2 (18.5～30.0 Hz) frequency bands. All values of the EEG power of MCI patients were found to be higher than those of normal controls at rest and during working memory tasks. Furthermore, the values of EEG power in the theta, alpha-1, alpha-2 and beta-1 bands of patients with MCI were significantly high (P＜0.05) in comparison with those of normal controls. Correlation analysis indicated a significant negative correlation between the EEG powers and MMSE scores. In addition, during working memory tasks, the EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P＜0.05). However, there was no significant difference in EEG coherences between two groups at rest. These findings comprise evidence that MCI patients have higher EEG power at rest, and higher EEG power and coherence during working conditions. It suggests that MCI may be associated with compensatory processes at

Spectral electroencephalogram in liver cirrhosis with minimal hepatic encephalopathy before and after lactulose therapy.

Science.gov (United States)

Singh, Jatinderpal; Sharma, Barjesh Chander; Maharshi, Sudhir; Puri, Vinod; Srivastava, Siddharth

2016-06-01

Minimal hepatic encephalopathy (MHE) represents the mildest form of hepatic encephalopathy. Spectral electroencephalogram (sEEG) analysis improves the recognition of MHE by decreasing inter-operator variability and providing quantitative parameters of brain dysfunction. We compared sEEG in patients with cirrhosis with and without MHE and the effects of lactulose on sEEG in patients with MHE. One hundred patients with cirrhosis (50 with and 50 without MHE) were enrolled. Diagnosis of MHE was based on psychometric hepatic encephalopathy score (PHES) of ≤ -5. Critical flicker frequency, model of end-stage liver disease score, and sEEG were performed at baseline in all patients. The spectral variables considered were the mean dominant frequency (MDF) and relative power in beta, alpha, theta, and delta bands. Patients with MHE were given 3 months of lactulose, and all parameters were repeated. Spectral electroencephalogram analysis showed lower MDF (7.8 ± 1.7 vs 8.7 ± 1.3 Hz, P < 0.05) and higher theta relative power (34.29 ± 4.8 vs 24 ± 6.7%, P = 001) while lower alpha relative power (28.6 ± 4.0 vs 33.5 ± 5.3%, P = .001) in patients with MHE than in patients without MHE. With theta relative power, sensitivity 96%, specificity 84%, and accuracy of 90% were obtained for diagnosis of MHE. After lactulose treatment, MHE improved in 21 patients, and significant changes were seen in MDF (7.8 ± 0.5 vs 8.5 ± 0.6), theta (34.2 ± 4.8 vs 23.3 ± 4.1%), alpha (28.6 ± 4.0 vs 35.5 ± 4.5%), and delta relative power (13.7 ± 3.5 vs 17.0 ± 3.3%) after treatment (P ≤ 0.05). Spectral EEG is a useful objective and quantitative tool for diagnosis and to assess the response to treatment in patients with cirrhosis with MHE. © 2015 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Angular correlation measurements for 4-{alpha} decaying states in {sup 16}O

Energy Technology Data Exchange (ETDEWEB)

Wuosmaa, A.H.; Back, B.B.; Betts, R.R. [and others

1995-08-01

Previous measurements of the {sup 12}C({sup 12}C,{sup 8}Be){sup 16}O{sup *}(4 {alpha}) reaction identified discrete levels in {sup 16}O which decay by breakup into 4 {alpha} particles through a number of different decay sequences, including {sup 16}O{sup *} {yields} {sup 8}Be + {sup 8}Be and {alpha} + {sup 12}C (O{sub 2}{sup +}). These states are observed in a range of excitation energies where resonances are observed in inelastic {alpha} + {sup 12}C scattering leading to the {sup 8}Be + {sup 8}Be and {alpha} + {sup 12}C final states. These resonances were associated with 4 {alpha}-particle chain configurations in {sup 16}O. Should the states populated in the {sup 12}C + {sup 12}C reaction possess this same extended structure, it would serve as an important piece of evidence supporting the idea that even more deformed structures are formed in the {sup 24}Mg compound system. In order to more firmly make this association, it is important to determine the spins of the states populated in the {sup 12}C + {sup 12}C reaction.

Genetic variability in the human cannabinoid receptor 1 is associated with resting state EEG theta power in humans.

Science.gov (United States)

Heitland, I; Kenemans, J L; Böcker, K B E; Baas, J M P

2014-11-01

It has long been postulated that exogenous cannabinoids have a profound effect on human cognitive functioning. These cannabinoid effects are thought to depend, at least in parts, on alterations of phase-locking of local field potential neuronal firing. The latter can be measured as activity in the theta frequency band (4-7Hz) by electroencephalogram. Theta oscillations are supposed to serve as a mechanism in neural representations of behaviorally relevant information. However, it remains unknown whether variability in endogenous cannabinoid activity is involved in theta rhythms and therefore, may serve as an individual differences index of human cognitive functioning. To clarify this issue, we recorded resting state EEG activity in 164 healthy human subjects and extracted EEG power across frequency bands (δ, θ, α, and β). To assess variability in the endocannabinoid system, two genetic polymorphisms (rs1049353, rs2180619) within the cannabinoid receptor 1 (CB1) were determined in all participants. As expected, we observed significant effects of rs1049353 on EEG power in the theta band at frontal, central and parietal electrode regions. Crucially, these effects were specific for the theta band, with no effects on activity in the other frequency bands. Rs2180619 showed no significant associations with theta power after Bonferroni correction. Taken together, we provide novel evidence in humans showing that genetic variability in the cannabinoid receptor 1 is associated with resting state EEG power in the theta frequency band. This extends prior findings of exogenous cannabinoid effects on theta power to the endogenous cannabinoid system. Copyright © 2014 Elsevier B.V. All rights reserved.

Modifications of EEG power spectra in mesial temporal lobe during n-back tasks of increasing difficulty. A sLORETA study.

Science.gov (United States)

Imperatori, Claudio; Farina, Benedetto; Brunetti, Riccardo; Gnoni, Valentina; Testani, Elisa; Quintiliani, Maria I; Del Gatto, Claudia; Indraccolo, Allegra; Contardi, Anna; Speranza, Anna M; Della Marca, Giacomo

2013-01-01

The n-back task is widely used to investigate the neural basis of Working Memory (WM) processes. The principal aim of this study was to explore and compare the EEG power spectra during two n-back tests with different levels of difficulty (1-back vs. 3-back). Fourteen healthy subjects were enrolled (seven men and seven women, mean age 31.21 ± 7.05 years, range: 23-48). EEG was recorded while performing the N-back test, by means of 19 surface electrodes referred to joint mastoids. EEG analysis were conducted by means of the standardized Low Resolution brain Electric Tomography (sLORETA) software. The statistical comparison between EEG power spectra in the two conditions was performed using paired t-statistics on the coherence values after Fisher's z transformation available in the LORETA program package. The frequency bands considered were: delta (0.5-4 Hz); theta (4.5-7.5 Hz); alpha (8-12.5 Hz); beta (13-30 Hz); gamma (30.5-100 Hz). Significant changes occurred in the delta band: in the 3-back condition an increased delta power was localized in a brain region corresponding to the Brodmann Area (BA) 28 in the left posterior entorhinal cortex (T = 3.112; p < 0.05) and in the BA 35 in the left perirhinal cortex in the parahippocampal gyrus (T = 2.876; p < 0.05). No significant differences were observed in the right hemisphere and in the alpha, theta, beta, and gamma frequency bands. Our results indicate that the most prominent modification induced by the increased complexity of the task occur in the mesial left temporal lobe structures.

Modifications of EEG Power Spectra in Mesial Temporal Lobe during n-back tasks of increasing difficulty. A sLORETA study.

Directory of Open Access Journals (Sweden)

Claudio eImperatori

2013-04-01

Full Text Available The n-back task is widely used to investigate the neural basis of Working Memory (WM processes. The principal aim of this study was to explore and compare the EEG power spectra during two n-back tests with different levels of difficulty (1-back vs 3-back.Fourteen healthy subjects were enrolled (7 men and 7 women, mean age 31.21±7.05 years, range: 23-48. EEG was recorded while performing the N-back test, by means of 19 surface electrodes referred to joint mastoids. EEG analysis were conducted by means of the standardized LOw Resolution brain Electric Tomography (sLORETA software. The statistical comparison between EEG power spectra in the two conditions was performed using paired t-statistics on the coherence values after Fisher’s z transformation available in the LORETA program package. The frequency bands considered were: delta (0.5-4 Hz; theta (4.5–7.5 Hz; alpha (8–12.5 Hz; beta (13–30 Hz; gamma (30.5–100 Hz. Significant changes occurred in the delta band: in the 3-back condition an increased delta power was localized in a brain region corresponding to the Brodmann Area (BA 28 in the left posterior entorhinal cortex (T = 3.112; p<0.05 and in the BA 35 in the left peririnhal cortex in the parahippocampal gyrus (T = 2.876; p<0.05. No significant differences were observed in the right hemisphere and in the alpha, theta, beta and gamma frequency bands. Our results indicate that the most prominent modification induced by the increased complexity of the task occur in the mesial left temporal lobe structures.

Supramodal Theta, Gamma, and Sustained Fields Predict Modality-specific Modulations of Alpha and Beta Oscillations during Visual and Tactile Working Memory.

Science.gov (United States)

van Ede, Freek; Jensen, Ole; Maris, Eric

2017-08-01

Flexible control over currently relevant sensory representations is an essential feature of primate cognition. We investigated the neurophysiological bases of such flexible control in humans during an intermodal working memory task in which participants retained visual or tactile sequences. Using magnetoencephalography, we first show that working memory retention engages early visual and somatosensory areas, as reflected in the sustained load-dependent suppression of alpha and beta oscillations. Next, we identify three components that are also load dependent but modality independent: medial prefrontal theta synchronization, frontoparietal gamma synchronization, and sustained parietal event-related fields. Critically, these domain-general components predict (across trials and within load conditions) the modality-specific suppression of alpha and beta oscillations, with largely unique contributions per component. Thus, working memory engages multiple complementary frontoparietal components that have discernible neuronal dynamics and that flexibly modulate retention-related activity in sensory areas in a manner that tracks the current contents of working memory.

The effect of task demand and incentive on neurophysiological and cardiovascular markers of effort.

Science.gov (United States)

Fairclough, Stephen H; Ewing, Kate

2017-09-01

According to motivational intensity theory, effort is proportional to the level of task demand provided that success is possible and successful performance is deemed worthwhile. The current study represents a simultaneous manipulation of demand (working memory load) and success importance (financial incentive) to investigate neurophysiological (EEG) and cardiovascular measures of effort. A 2×2 repeated-measures study was conducted where 18 participants performed a n-back task under three conditions of demand: easy (1-back), hard (4-back) and very hard (7-back). In addition, participants performed these tasks in the presence of performance-contingent financial incentive or in a no-incentive (pilot trial) condition. Three bands of EEG activity were quantified: theta (4-7Hz), lower-alpha (7.5-10Hz) and upper-alpha (10.5-13Hz). Fronto-medial activity in the theta band and activity in the upper-alpha band at frontal, central and parietal sites were sensitive to demand and indicated greatest effort when the task was challenging and success was possible. Mean systolic blood pressure and activity in the lower-alpha band at parietal sites were also sensitive to demand but also increased in the incentive condition across all levels of task demand. The results of the study largely support the predictions of motivational intensity using neurophysiological markers of effort. Copyright © 2017. Published by Elsevier B.V.

Neural dynamics during repetitive visual stimulation

Science.gov (United States)

Tsoneva, Tsvetomira; Garcia-Molina, Gary; Desain, Peter

2015-12-01

Objective. Steady-state visual evoked potentials (SSVEPs), the brain responses to repetitive visual stimulation (RVS), are widely utilized in neuroscience. Their high signal-to-noise ratio and ability to entrain oscillatory brain activity are beneficial for their applications in brain-computer interfaces, investigation of neural processes underlying brain rhythmic activity (steady-state topography) and probing the causal role of brain rhythms in cognition and emotion. This paper aims at analyzing the space and time EEG dynamics in response to RVS at the frequency of stimulation and ongoing rhythms in the delta, theta, alpha, beta, and gamma bands. Approach.We used electroencephalography (EEG) to study the oscillatory brain dynamics during RVS at 10 frequencies in the gamma band (40-60 Hz). We collected an extensive EEG data set from 32 participants and analyzed the RVS evoked and induced responses in the time-frequency domain. Main results. Stable SSVEP over parieto-occipital sites was observed at each of the fundamental frequencies and their harmonics and sub-harmonics. Both the strength and the spatial propagation of the SSVEP response seem sensitive to stimulus frequency. The SSVEP was more localized around the parieto-occipital sites for higher frequencies (>54 Hz) and spread to fronto-central locations for lower frequencies. We observed a strong negative correlation between stimulation frequency and relative power change at that frequency, the first harmonic and the sub-harmonic components over occipital sites. Interestingly, over parietal sites for sub-harmonics a positive correlation of relative power change and stimulation frequency was found. A number of distinct patterns in delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz) and beta (15-30 Hz) bands were also observed. The transient response, from 0 to about 300 ms after stimulation onset, was accompanied by increase in delta and theta power over fronto-central and occipital sites, which returned to baseline

Absorption and transport of deuterium-substituted 2R,4'R,8'R-alpha-tocopherol in human lipoproteins

International Nuclear Information System (INIS)

Traber, M.G.; Ingold, K.U.; Burton, G.W.; Kayden, H.J.

1988-01-01

Oral administration of a single dose of tri- or hexadeuterium substituted 2R,4'R,8'R-alpha-tocopheryl acetate (d3- or d6-alpha-T-Ac) to humans was used to follow the absorption and transport of vitamin E in plasma lipoproteins. Three hr after oral administration of d3-alpha-T-Ac (15 mg) to 2 subjects, plasma levels of d3-alpha-T were detectable; these increased up to 10 hr, reached a plateau at 24 hr, then decreased. Following administration of d6-alpha-T-Ac (15-16 mg) to 2 subjects, the percentage of deuterated tocopherol relative to the total tocopherol in chylomicrons increased more rapidly than the corresponding percentage in whole plasma. Chylomicrons and plasma lipoproteins were isolated from 2 additional subjects following administration of d3-alpha-T-Ac (140 or 60 mg). The percentage of deuterated tocopherol relative to the total tocopherol increased most rapidly in chylomicrons, then in very low density lipoproteins (VLDL), followed by essentially identical increases in low and high density lipoproteins (LDL and HDL, respectively) and lastly, in the red blood cells. This pattern of appearance of deuterated tocopherol is consistent with the concept that newly absorbed vitamin E is secreted by the intestine into chylomicrons; subsequently, chylomicron remnants are taken up by the liver from which the vitamin E is secreted in VLDL. The metabolism of VLDL in the circulation results in the simultaneous delivery of vitamin E into LDL and HDL

Increased frequency of CD4{sup -}8{sup -}T cells bearing T-cell receptor {alpha}{beta} chains in peripheral blood of atomic bomb survivors exposed to high doses

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Yoichiro Kusunoki; Seishi Kyoizumi; Yuko Hirai; Shoichiro Fujita; Mitoshi Akiyama [Radiation Effects Research Foundation, Hiroshima (Japan)

1994-07-01

A rare T-cell subpopulation, CD4{sup -z}8{sup -}{alpha}{beta} cells, may be differentiated through a pathway (or pathways) different from the pathway(s) of conventional CD4+ or CD8+ cells. In the present study, the frequencies of CD4{sup -}8{sup -} T cells in peripheral-blood {alpha}{beta} T cells in 409 atomic bomb survivors were determined to investigate late effects of radiation on the composition of human T-cell subpopulations. The frequency of CD4{sup -}8{sup -}{alpha}{beta} T-cell decreased significantly with the subject`s age and was higher in females than males. A significant increase in the frequency was found in the survivors exposed to more than 1.5Gy, suggesting that the previous radiation exposure altered differentiation and development of T cells. 25 refs., 4 figs., 3 tabs.

Unconsciousness, automatisms, and myoclonic jerks with diffuse rhythmic 9-Hz discharges.

Science.gov (United States)

Nadel, A; Waddell, G; Volow, M; Escueta, A V

1975-09-01

A 25-year-old man presented with seizures characterized by unconsciousness, automatic behavior, and myoclonic jerks lasting 0.5 to 8 sec. Videotape analysis of 300 simultaneously recorded electroencephalographic and clinical attacks revealed 8- to 9-Hz 150 to 200 muV sharp waves beginning in both medial temporal areas during eyelid flutters. When discharges spread diffusely on both sides and lasted 2 to 3 sec, 20 degrees forward flexion of the head, unconsciousness, pupil dilation, and staring became evident. Asymmetrical myoclonic jerks invariably appeared. When paroxysms were greater than 3 sec, automatisms and tonic posturing occurred. The electroencephalographic and clinical seizures appeared during the awake and relaxed states, i.e., with normal alpha rhythm. They were suppressed during physical and mental activities and during sleep, i.e., in the absence of alpha rhythm. Our studies suggest that these seizures associated with diffuse electroencephalographic alpha-like activities are subcortical in origin and should be tested in their responsivity to alpha suppressants and inducers.

Neurofeedback in Learning Disabled Children: Visual versus Auditory Reinforcement.

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Fernández, Thalía; Bosch-Bayard, Jorge; Harmony, Thalía; Caballero, María I; Díaz-Comas, Lourdes; Galán, Lídice; Ricardo-Garcell, Josefina; Aubert, Eduardo; Otero-Ojeda, Gloria

2016-03-01

Children with learning disabilities (LD) frequently have an EEG characterized by an excess of theta and a deficit of alpha activities. NFB using an auditory stimulus as reinforcer has proven to be a useful tool to treat LD children by positively reinforcing decreases of the theta/alpha ratio. The aim of the present study was to optimize the NFB procedure by comparing the efficacy of visual (with eyes open) versus auditory (with eyes closed) reinforcers. Twenty LD children with an abnormally high theta/alpha ratio were randomly assigned to the Auditory or the Visual group, where a 500 Hz tone or a visual stimulus (a white square), respectively, was used as a positive reinforcer when the value of the theta/alpha ratio was reduced. Both groups had signs consistent with EEG maturation, but only the Auditory Group showed behavioral/cognitive improvements. In conclusion, the auditory reinforcer was more efficacious in reducing the theta/alpha ratio, and it improved the cognitive abilities more than the visual reinforcer.

Theta and beta oscillatory dynamics in the dentate gyrus reveal a shift in network processing state during cue encounters

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Lara Maria Rangel

2015-07-01

Full Text Available The hippocampus is an important structure for learning and memory processes, and has strong rhythmic activity. Although a large amount of research has been dedicated towards understanding the rhythmic activity in the hippocampus during exploratory behaviors, specifically in the theta (5-10 Hz frequency range, few studies have examined the temporal interplay of theta and other frequencies during the presentation of meaningful cues. We obtained in vivo electrophysiological recordings of local field potentials (LFP in the dentate gyrus (DG of the hippocampus as rats performed three different associative learning tasks. In each task, cue presentations elicited pronounced decrements in theta amplitude in conjunction with increases in beta (15-30Hz amplitude. These changes were often transient but were sustained from the onset of cue encounters until the occurrence of a reward outcome. This oscillatory profile shifted in time to precede cue encounters over the course of the session, and was not present during similar behavior in the absence of task relevant stimuli. The observed decreases in theta amplitude and increases in beta amplitude in the dentate gyrus may thus reflect a shift in processing state that occurs when encountering meaningful cues.

Frequency modulation of neural oscillations according to visual task demands.

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Wutz, Andreas; Melcher, David; Samaha, Jason

2018-02-06

Temporal integration in visual perception is thought to occur within cycles of occipital alpha-band (8-12 Hz) oscillations. Successive stimuli may be integrated when they fall within the same alpha cycle and segregated for different alpha cycles. Consequently, the speed of alpha oscillations correlates with the temporal resolution of perception, such that lower alpha frequencies provide longer time windows for perceptual integration and higher alpha frequencies correspond to faster sampling and segregation. Can the brain's rhythmic activity be dynamically controlled to adjust its processing speed according to different visual task demands? We recorded magnetoencephalography (MEG) while participants switched between task instructions for temporal integration and segregation, holding stimuli and task difficulty constant. We found that the peak frequency of alpha oscillations decreased when visual task demands required temporal integration compared with segregation. Alpha frequency was strategically modulated immediately before and during stimulus processing, suggesting a preparatory top-down source of modulation. Its neural generators were located in occipital and inferotemporal cortex. The frequency modulation was specific to alpha oscillations and did not occur in the delta (1-3 Hz), theta (3-7 Hz), beta (15-30 Hz), or gamma (30-50 Hz) frequency range. These results show that alpha frequency is under top-down control to increase or decrease the temporal resolution of visual perception.

Transient Global Amnesia Deteriorates the Network Efficiency of the Theta Band.

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Young Ho Park

Full Text Available Acute perturbation of the hippocampus, one of the connector hubs in the brain, is a key step in the pathophysiological cascade of transient global amnesia (TGA. We tested the hypothesis that network efficiency, meaning the efficiency of information exchange over a network, is impaired during the acute stage of TGA. Graph theoretical analysis was applied to resting-state EEG data collected from 21 patients with TGA. The EEG data were obtained twice, once during the acute stage ( 2 months after symptom onset of TGA. Characteristic path lengths and clustering coefficients of functional networks constructed using phase-locking values were computed and normalized as a function of the degree in the delta, theta, alpha, beta 1, beta 2 and gamma frequency bands of the EEG. We investigated whether the normalized characteristic path length (nCPL and normalized clustering coefficients (nCC differed significantly between the acute and resolved stages of TGA at each frequency band using the Wilcoxon signed-rank test. For networks where the nCPL or nCC differed significantly between the two stages, we also evaluated changes in the connections of the brain networks. During the acute stage of TGA, the nCPL of the theta band networks with mean degrees of 8, 8.5, 9 and 9.5 significantly increased (P < 0.05. During the acute stage, the lost edges for these networks were mostly found between the anterior (frontal and anterior temporal and posterior (parieto-occipital and posterior temporal brain regions, whereas newly developed edges were primarily found between the left and right frontotemporal regions. The nCC of the theta band with a mean degree of 5.5 significantly decreased during the acute stage (P < 0.05. Our results indicate that TGA deteriorates the network efficiency of the theta frequency band. This effect might be related to the desynchronization between the anterior and posterior brain areas.

Areas V1 and V2 show microsaccade-related 3-4-Hz covariation in gamma power and frequency.

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Lowet, E; Roberts, M J; Bosman, C A; Fries, P; De Weerd, P

2016-05-01

Neuronal gamma-band synchronization (25-80 Hz) in visual cortex appears sustained and stable during prolonged visual stimulation when investigated with conventional averages across trials. However, recent studies in macaque visual cortex have used single-trial analyses to show that both power and frequency of gamma oscillations exhibit substantial moment-by-moment variation. This has raised the question of whether these apparently random variations might limit the functional role of gamma-band synchronization for neural processing. Here, we studied the moment-by-moment variation in gamma oscillation power and frequency, as well as inter-areal gamma synchronization, by simultaneously recording local field potentials in V1 and V2 of two macaque monkeys. We additionally analyzed electrocorticographic V1 data from a third monkey. Our analyses confirm that gamma-band synchronization is not stationary and sustained but undergoes moment-by-moment variations in power and frequency. However, those variations are neither random and nor a possible obstacle to neural communication. Instead, the gamma power and frequency variations are highly structured, shared between areas and shaped by a microsaccade-related 3-4-Hz theta rhythm. Our findings provide experimental support for the suggestion that cross-frequency coupling might structure and facilitate the information flow between brain regions. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Discovery of 1-5 Hz flaring at high luminosity in SAX J1808.4-3658

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Bult, Peter; Van der Klis, Michiel, E-mail: p.m.bult@uva.nl [Anton Pannekoek Institute, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands)

2014-07-10

We report the discovery of a 1-5 Hz X-ray flaring phenomenon observed at >30 mCrab near peak luminosity in the 2008 and 2011 outbursts of the accreting millisecond X-ray pulsar SAX J1808.4-3658 in observations with the Rossi X-ray Timing Explorer. In each of the two outbursts this high luminosity flaring is seen for ∼3 continuous days and switches on and off on a timescale of 1-2 hr. The flaring can be seen directly in the light curve, where it shows sharp spikes of emission at quasi-regular separation. In the power spectrum it produces a broad noise component, which peaks at 1-5 Hz. The total 0.05-10 Hz variability has a fractional rms amplitude of 20%-45%, well in excess of the 8%-12% rms broadband noise usually seen in power spectra of SAX J1808.4-3658. We perform a detailed timing analysis of the flaring and study its relation to the 401 Hz pulsations. We find that the pulse amplitude varies proportionally with source flux through all phases of the flaring, indicating that the flaring is likely due to mass density variations created at or outside the magnetospheric boundary. We suggest that this 1-5 Hz flaring is a high mass accretion rate version of the 0.5-2 Hz flaring which is known to occur at low luminosity (<13 mCrab), late in the tail of outbursts of SAX J1808.4-3658. We propose the dead-disk instability, previously suggested as the mechanism for the 0.5-2 Hz flaring, as a likely mechanism for the high luminosity flaring reported here.

Chemotherapy disrupts learning, neurogenesis and theta activity in the adult brain.

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Nokia, Miriam S; Anderson, Megan L; Shors, Tracey J

2012-12-01

Chemotherapy, especially if prolonged, disrupts attention, working memory and speed of processing in humans. Most cancer drugs that cross the blood-brain barrier also decrease adult neurogenesis. Because new neurons are generated in the hippocampus, this decrease may contribute to the deficits in working memory and related thought processes. The neurophysiological mechanisms that underlie these deficits are generally unknown. A possible mediator is hippocampal oscillatory activity within the theta range (3-12 Hz). Theta activity predicts and promotes efficient learning in healthy animals and humans. Here, we hypothesised that chemotherapy disrupts learning via decreases in hippocampal adult neurogenesis and theta activity. Temozolomide was administered to adult male Sprague-Dawley rats in a cyclic manner for several weeks. Treatment was followed by training with different types of eyeblink classical conditioning, a form of associative learning. Chemotherapy reduced both neurogenesis and endogenous theta activity, as well as disrupted learning and related theta-band responses to the conditioned stimulus. The detrimental effects of temozolomide only occurred after several weeks of treatment, and only on a task that requires the association of events across a temporal gap and not during training with temporally overlapping stimuli. Chemotherapy did not disrupt the memory for previously learned associations, a memory independent of (new neurons in) the hippocampus. In conclusion, prolonged systemic chemotherapy is associated with a decrease in hippocampal adult neurogenesis and theta activity that may explain the selective deficits in processes of learning that describe the 'chemobrain'. © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

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

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Nadia Gulluni

2018-01-01

Full Text Available 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.

Meditation is associated with increased brain network integration.

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van Lutterveld, Remko; van Dellen, Edwin; Pal, Prasanta; Yang, Hua; Stam, Cornelis Jan; Brewer, Judson

2017-09-01

This study aims to identify novel quantitative EEG measures associated with mindfulness meditation. As there is some evidence that meditation is associated with higher integration of brain networks, we focused on EEG measures of network integration. Sixteen novice meditators and sixteen experienced meditators participated in the study. Novice meditators performed a basic meditation practice that supported effortless awareness, which is an important quality of experience related to mindfulness practices, while their EEG was recorded. Experienced meditators performed a self-selected meditation practice that supported effortless awareness. Network integration was analyzed with maximum betweenness centrality and leaf fraction (which both correlate positively with network integration) as well as with diameter and average eccentricity (which both correlate negatively with network integration), based on a phase-lag index (PLI) and minimum spanning tree (MST) approach. Differences between groups were assessed using repeated-measures ANOVA for the theta (4-8 Hz), alpha (8-13 Hz) and lower beta (13-20 Hz) frequency bands. Maximum betweenness centrality was significantly higher in experienced meditators than in novices (P = 0.012) in the alpha band. In the same frequency band, leaf fraction showed a trend toward being significantly higher in experienced meditators than in novices (P = 0.056), while diameter and average eccentricity were significantly lower in experienced meditators than in novices (P = 0.016 and P = 0.028 respectively). No significant differences between groups were observed for the theta and beta frequency bands. These results show that alpha band functional network topology is better integrated in experienced meditators than in novice meditators during meditation. This novel finding provides the rationale to investigate the temporal relation between measures of functional connectivity network integration and meditation quality, for example using

The effects of analgesics on central processing of tonic pain

DEFF Research Database (Denmark)

Lelic, Dina; Hansen, Tine M; Mark, Esben Bolvig

2017-01-01

to tonic pain is modified by oxycodone (opioid) and venlafaxine (SNRI). Methods Twenty healthy males were included in this randomized, cross-over, double-blinded study. 61-channel electroencephalogram (EEG) was recorded before and after five days of treatment with placebo, oxycodone (10 mg extended release......Introduction Opioids and antidepressants that inhibit serotonin and norepinephrine reuptake (SNRI) are recognized as analgesics to treat moderate to severe pain, but the central mechanisms underlying their analgesia remain unclear. This study investigated how brain activity at rest and exposed...... b.i.d) or venlafaxine (37.5 mg extended release b.i.d) at rest and during tonic pain (hand immersed in 2 °C water for 80 s). Subjective pain and unpleasantness scores of tonic pain were recorded. Spectral analysis and sLORETA source localization were done in delta (1–4 Hz), theta (4–8 Hz), alpha (8...

Influence of Fragrances on Human Psychophysiological Activity: With Special Reference to Human Electroencephalographic Response

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Kandhasamy Sowndhararajan

2016-11-01

Full Text Available The influence of fragrances such as perfumes and room fresheners on the psychophysiological activities of humans has been known for a long time, and its significance is gradually increasing in the medicinal and cosmetic industries. A fragrance consists of volatile chemicals with a molecular weight of less than 300 Da that humans perceive through the olfactory system. In humans, about 300 active olfactory receptor genes are devoted to detecting thousands of different fragrance molecules through a large family of olfactory receptors of a diverse protein sequence. The sense of smell plays an important role in the physiological effects of mood, stress, and working capacity. Electrophysiological studies have revealed that various fragrances affected spontaneous brain activities and cognitive functions, which are measured by an electroencephalograph (EEG. The EEG is a good temporal measure of responses in the central nervous system and it provides information about the physiological state of the brain both in health and disease. The EEG power spectrum is classified into different frequency bands such as delta (0.5–4 Hz, theta (4–8 Hz, alpha (8–13 Hz, beta (13–30 Hz and gamma (30–50 Hz, and each band is correlated with different features of brain states. A quantitative EEG uses computer software to provide the topographic mapping of the brain activity in frontal, temporal, parietal and occipital brain regions. It is well known that decreases of alpha and beta activities and increases of delta and theta activities are associated with brain pathology and general cognitive decline. In the last few decades, many scientific studies were conducted to investigate the effect of inhalation of aroma on human brain functions. The studies have suggested a significant role for olfactory stimulation in the alteration of cognition, mood, and social behavior. This review aims to evaluate the available literature regarding the influence of fragrances on the

Influence of Fragrances on Human Psychophysiological Activity: With Special Reference to Human Electroencephalographic Response

Science.gov (United States)

Sowndhararajan, Kandhasamy; Kim, Songmun

2016-01-01

The influence of fragrances such as perfumes and room fresheners on the psychophysiological activities of humans has been known for a long time, and its significance is gradually increasing in the medicinal and cosmetic industries. A fragrance consists of volatile chemicals with a molecular weight of less than 300 Da that humans perceive through the olfactory system. In humans, about 300 active olfactory receptor genes are devoted to detecting thousands of different fragrance molecules through a large family of olfactory receptors of a diverse protein sequence. The sense of smell plays an important role in the physiological effects of mood, stress, and working capacity. Electrophysiological studies have revealed that various fragrances affected spontaneous brain activities and cognitive functions, which are measured by an electroencephalograph (EEG). The EEG is a good temporal measure of responses in the central nervous system and it provides information about the physiological state of the brain both in health and disease. The EEG power spectrum is classified into different frequency bands such as delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–13 Hz), beta (13–30 Hz) and gamma (30–50 Hz), and each band is correlated with different features of brain states. A quantitative EEG uses computer software to provide the topographic mapping of the brain activity in frontal, temporal, parietal and occipital brain regions. It is well known that decreases of alpha and beta activities and increases of delta and theta activities are associated with brain pathology and general cognitive decline. In the last few decades, many scientific studies were conducted to investigate the effect of inhalation of aroma on human brain functions. The studies have suggested a significant role for olfactory stimulation in the alteration of cognition, mood, and social behavior. This review aims to evaluate the available literature regarding the influence of fragrances on the

Patients with Rheumatoid Arthritis and Chronic Pain Display Enhanced Alpha Power Density at Rest.

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Meneses, Francisco M; Queirós, Fernanda C; Montoya, Pedro; Miranda, José G V; Dubois-Mendes, Selena M; Sá, Katia N; Luz-Santos, Cleber; Baptista, Abrahão F

2016-01-01

Patients with chronic pain due to neuropathy or musculoskeletal injury frequently exhibit reduced alpha and increased theta power densities. However, little is known about electrical brain activity and chronic pain in patients with rheumatoid arthritis (RA). For this purpose, we evaluated power densities of spontaneous electroencephalogram (EEG) band frequencies (delta, theta, alpha, and beta) in females with persistent pain due to RA. This was a cross-sectional study of 21 participants with RA and 21 healthy controls (mean age = 47.20; SD = 10.40). EEG was recorded at rest over 5 min with participant's eyes closed. Twenty electrodes were placed over five brain regions (frontal, central, parietal, temporal, and occipital). Significant differences were observed in depression and anxiety with higher scores in RA participants than healthy controls (p = 0.002). Participants with RA exhibited increased average absolute alpha power density in all brain regions when compared to controls [F (1.39) = 6.39, p = 0.016], as well as increased average relative alpha power density [F (1.39) = 5.82, p = 0.021] in all regions, except the frontal region, controlling for depression/anxiety. Absolute theta power density also increased in the frontal, central, and parietal regions for participants with RA when compared to controls [F (1, 39) = 4.51, p = 0.040], controlling for depression/anxiety. Differences were not exhibited on beta and delta absolute and relative power densities. The diffuse increased alpha may suggest a possible neurogenic mechanism for chronic pain in individuals with RA.

Classical Conditioning of Hippocampal Theta Patterns in the Rat.

Science.gov (United States)

1976-08-01

associated with changes in performance of learned tasks , 1,4,5, 8,9 there have been very few studies of neurona l plasticity of the hippocampus It self...rapid development of a conditioned hippocampal theta response to a visual sti mulus demonstrates tha t there is considerable neurona l plasticity in the

[Flexibility of cognitive activity depends on its context].

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Kostandov, É A

2010-01-01

The main purpose of this survey is to explain the importance of set-shifting for a flexible cognitive activity. Working memory overload may result in set-shifting slowdown, i.e., in a more rigid set and in a less flexible cognitive activity. This effect displays itself in an increase of erroneous perceptions of external stimuli. Set rigidity level also depends on the cognitive activity context (i.e., on the type of external stimuli the person has to deal with). We analyzed EEG-coherence function and induced synchronization/desynchronization responses in theta (4-7 Hz) and low alpha (8-10 Hz) bands. Basing on these data, we discuss the role of tonic and phasic forms of cortico-hippocampal and fronto-thalamic systems' activation in cognitive activity flexibility.

Power spectral analysis of the sleep electroencephalogram in heartburn patients with or without gastroesophageal reflux disease: a feasibility study.

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Budhiraja, Rohit; Quan, Stuart F; Punjabi, Naresh M; Drake, Christopher L; Dickman, Ram; Fass, Ronnie

2010-02-01

Determine the feasibility of using power spectrum of the sleep electroencephalogram (EEG) as a more sensitive tool than sleep architecture to evaluate the relationship between gastroesophageal reflux disease (GERD) and sleep. GERD has been shown to adversely affect subjective sleep reports but not necessarily objective sleep parameters. Data were prospectively collected from symptomatic patients with heartburn. All symptomatic patients underwent upper endoscopy. Patients without erosive esophagitis underwent pH testing. Sleep was polygraphically recorded in the laboratory. Spectral analysis was performed to determine the power spectrum in 4 bandwidths: delta (0.8 to 4.0 Hz), theta (4.1 to 8.0 Hz), alpha (8.1 to 13.0 Hz), and beta (13.1 to 20.0 Hz). Eleven heartburn patients were included in the GERD group (erosive esophagitis) and 6 heartburn patients in the functional heartburn group (negative endoscopy, pH test, response to proton pump inhibitors). The GERD patients had evidence of lower average delta-power than functional heartburn patients. Patients with GERD had greater overall alpha-power in the latter half of the night (3 hours after sleep onset) than functional heartburn patients. No significant differences were noted in conventional sleep stage summaries between the 2 groups. Among heartburn patients with GERD, EEG spectral power during sleep is shifted towards higher frequencies compared with heartburn patients without GERD despite similar sleep architecture. This feasibility study demonstrated that EEG spectral power during sleep might be the preferred tool to provide an objective analysis about the effect of GERD on sleep.

Damping constant of Co/Pt multilayer thin-film media

Energy Technology Data Exchange (ETDEWEB)

Fujita, N. [Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510 (Japan); Inaba, N. [Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510 (Japan)], E-mail: inaba@yz.yamagata-u.ac.jp; Kirino, F. [National University of Fine Arts and Music, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8577 (Japan); Igarashi, S.; Koike, K.; Kato, H. [Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510 (Japan)

2008-11-15

Gilbert's damping constants, {alpha}, of Co(t{sub Co})/Pt (1.4 nm) multilayer thin films are investigated by Q-band FMR analysis. {alpha} is calculated from the resonance width of the FMR spectrum. With decreasing t{sub Co}, the {alpha} value decreases from 0.034 (t{sub Co}=8.7 nm) to 0.023 (t{sub Co}=1.8 nm), and then increases to 0.037 (t{sub Co}=1.0 nm). The decrease of {alpha} with t{sub Co}>1.8 nm is probably due to the eddy current loss effects. The increase of {alpha} with t{sub Co}<1.8 nm would be caused by the increase of the distortion between the Co and the Pt layers at the interface. When the magnetic field direction was changed from {theta}=90 deg. (parallel to the specimen) to {theta}=0 deg. (perpendicular to the specimen), the {alpha} of all the specimens increased, and a sharp step in {alpha} was observed around {theta}=40 deg., where the {alpha} has the maximum value.

Alpha-Band Rhythms in Visual Task Performance: Phase-Locking by Rhythmic Sensory Stimulation

Science.gov (United States)

de Graaf, Tom A.; Gross, Joachim; Paterson, Gavin; Rusch, Tessa; Sack, Alexander T.; Thut, Gregor

2013-01-01

Oscillations are an important aspect of neuronal activity. Interestingly, oscillatory patterns are also observed in behaviour, such as in visual performance measures after the presentation of a brief sensory event in the visual or another modality. These oscillations in visual performance cycle at the typical frequencies of brain rhythms, suggesting that perception may be closely linked to brain oscillations. We here investigated this link for a prominent rhythm of the visual system (the alpha-rhythm, 8–12 Hz) by applying rhythmic visual stimulation at alpha-frequency (10.6 Hz), known to lead to a resonance response in visual areas, and testing its effects on subsequent visual target discrimination. Our data show that rhythmic visual stimulation at 10.6 Hz: 1) has specific behavioral consequences, relative to stimulation at control frequencies (3.9 Hz, 7.1 Hz, 14.2 Hz), and 2) leads to alpha-band oscillations in visual performance measures, that 3) correlate in precise frequency across individuals with resting alpha-rhythms recorded over parieto-occipital areas. The most parsimonious explanation for these three findings is entrainment (phase-locking) of ongoing perceptually relevant alpha-band brain oscillations by rhythmic sensory events. These findings are in line with occipital alpha-oscillations underlying periodicity in visual performance, and suggest that rhythmic stimulation at frequencies of intrinsic brain-rhythms can be used to reveal influences of these rhythms on task performance to study their functional roles. PMID:23555873

Theta oscillations are sensitive to both early and late conflict processing stages: effects of alcohol intoxication.

Science.gov (United States)

Kovacevic, Sanja; Azma, Sheeva; Irimia, Andrei; Sherfey, Jason; Halgren, Eric; Marinkovic, Ksenija

2012-01-01

Prior neuroimaging evidence indicates that decision conflict activates medial and lateral prefrontal and parietal cortices. Theoretical accounts of cognitive control highlight anterior cingulate cortex (ACC) as a central node in this network. However, a better understanding of the relative primacy and functional contributions of these areas to decision conflict requires insight into the neural dynamics of successive processing stages including conflict detection, response selection and execution. Moderate alcohol intoxication impairs cognitive control as it interferes with the ability to inhibit dominant, prepotent responses when they are no longer correct. To examine the effects of moderate intoxication on successive processing stages during cognitive control, spatio-temporal changes in total event-related theta power were measured during Stroop-induced conflict. Healthy social drinkers served as their own controls by participating in both alcohol (0.6 g/kg ethanol for men, 0.55 g/kg women) and placebo conditions in a counterbalanced design. Anatomically-constrained magnetoencephalography (aMEG) approach was applied to complex power spectra for theta (4-7 Hz) frequencies. The principal generator of event-related theta power to conflict was estimated to ACC, with contributions from fronto-parietal areas. The ACC was uniquely sensitive to conflict during both early conflict detection, and later response selection and execution stages. Alcohol attenuated theta power to conflict across successive processing stages, suggesting that alcohol-induced deficits in cognitive control may result from theta suppression in the executive network. Slower RTs were associated with attenuated theta power estimated to ACC, indicating that alcohol impairs motor preparation and execution subserved by the ACC. In addition to their relevance for the currently prevailing accounts of cognitive control, our results suggest that alcohol-induced impairment of top-down strategic processing

EEG responses to low-level chemicals in normals and cacosmics.

Science.gov (United States)

Schwartz, G E; Bell, I R; Dikman, Z V; Fernandez, M; Kline, J P; Peterson, J M; Wright, K P

1994-01-01

Recent studies from the University of Arizona indicate that normal subjects, both college students and the elderly, can register the presence of low-intensity odors in the electroencephalogram (EEG) in the absence of conscious awareness of the odors. The experimental paradigm involves subjects sniffing pairs of bottles, one containing an odorant (e.g. isoamyl acetate) dissolved in an odorless solvent (water or liquid silicone), the other containing just the solvent, while 19 channels of EEG are continuously recorded. For the low-intensity odor conditions, concentrations are adjusted downward (decreased) until subjects correctly identify the odor bottle at chance (50%). The order of odorants, concentrations, and hand holding the control bottle, are counterbalanced within and across subjects. Three previous experiments found that alpha activity (8-12 hz) decreased in midline and posterior regions when subjects sniffed the low-intensity odors. The most recent study suggests that decreased theta activity (4-8 hz) may reflect sensory registration and decreased alpha activity may reflect perceptual registration. In a just completed experiment involving college students who were selected based on combinations of high and low scores on a scale measuring cacosmia (chemical odor intolerance) and high and low scores on a scale measuring depression, cacosmic subjects (independent of depression) showed greater decreases in low-frequency alpha (8-10 hz) and greater increases in low-frequency beta (12-16 hz) to the solvent propylene glycol compared to an empty bottle. Topographic EEG mapping to low-intensity odorants may provide a useful tool for investigating possible increased sensitivity to specific chemicals in chemically sensitive individuals.

Complementary theta resonance filtering by two spatially segregated mechanisms in CA1 hippocampal pyramidal neurons.

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Hu, Hua; Vervaeke, Koen; Graham, Lyle J; Storm, Johan F

2009-11-18

Synaptic input to a neuron may undergo various filtering steps, both locally and during transmission to the soma. Using simultaneous whole-cell recordings from soma and apical dendrites from rat CA1 hippocampal pyramidal cells, and biophysically detailed modeling, we found two complementary resonance (bandpass) filters of subthreshold voltage signals. Both filters favor signals in the theta (3-12 Hz) frequency range, but have opposite location, direction, and voltage dependencies: (1) dendritic H-resonance, caused by h/HCN-channels, filters signals propagating from soma to dendrite when the membrane potential is close to rest; and (2) somatic M-resonance, caused by M/Kv7/KCNQ and persistent Na(+) (NaP) channels, filters signals propagating from dendrite to soma when the membrane potential approaches spike threshold. Hippocampal pyramidal cells participate in theta network oscillations during behavior, and we suggest that that these dual, polarized theta resonance mechanisms may convey voltage-dependent tuning of theta-mediated neural coding in the entorhinal/hippocampal system during locomotion, spatial navigation, memory, and sleep.

Alcohol Hits You When It Is Hard: Intoxication, Task Difficulty, and Theta Brain Oscillations.

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Rosen, Burke Q; Padovan, Nevena; Marinkovic, Ksenija

2016-04-01

Alcohol intoxication is known to impair decision making in a variety of situations. Previous neuroimaging evidence suggests that the neurofunctional system subserving controlled processing is especially vulnerable to alcohol in conflict-evoking tasks. The present study investigated the effects of moderate alcohol intoxication on the spatiotemporal neural dynamics of event-related total theta (4 to 7 Hz) power as a function of task difficulty. Two variants of the Simon task manipulated incongruity via simple spatial stimulus-response mismatch and, in a more difficult version, by combining spatial and semantic interference. Healthy social drinkers participated in both alcohol (0.6 g/kg ethanol for men, 0.55 g/kg for women) and placebo conditions in a counterbalanced design. Whole-head magnetoencephalography (MEG) signals were acquired and event-related total theta power was calculated on each trial with Morlet wavelets. MEG sources were estimated using anatomically constrained, noise-normalized, spectral dynamic statistical parametric mapping. Longer reaction times and lower accuracy confirmed the difficulty manipulation. Response conflict (incongruity) increased and alcohol intoxication decreased event-related theta power overall during both tasks bilaterally in the medial and ventrolateral prefrontal cortices. However, alcohol-induced theta suppression was selective for conflict only in the more difficult task which engaged the dorsal anterior cingulate (dAC) and anterior inferolateral prefrontal cortices. Theta power correlated negatively with drinking levels and disinhibition, suggesting that cognitive control is susceptible in more impulsive individuals with higher alcohol intake. The spatiotemporal theta profile across the 2 tasks supports the concept of a rostrocaudal activity gradient in the medial prefrontal cortex that is modulated by task difficulty, with the dAC as the key node in the network subserving cognitive control. Conflict-related theta power was

Noninvasive focused ultrasound stimulation can modulate phase-amplitude coupling between neuronal oscillations in the rat hippocampus

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Yi Yuan

2016-07-01

Full Text Available Noninvasive focused ultrasound stimulation (FUS can be used to modulate neural activity with high spatial resolution. Phase-amplitude coupling (PAC between neuronal oscillations is tightly associated with cognitive processes, including learning, attention and memory. In this study, we investigated the effect of FUS on PAC between neuronal oscillations and established the relationship between the PAC index and ultrasonic intensity. The rat hippocampus was stimulated using focused ultrasound at different spatial-average pulse-average ultrasonic intensities (3.9 W/cm2, 9.6 W/cm2, and 19.2 W/cm2. The local field potentials (LFPs in the rat hippocampus were recorded before and after FUS. Then, we analyzed PAC between neuronal oscillations using a PAC calculation algorithm. Our results showed that FUS significantly modulated PAC between the theta (4-8 Hz and gamma (30-80 Hz bands and between the alpha (9-13 Hz and ripple (81-200 Hz bands in the rat hippocampus, and PAC increased with incremental increases in ultrasonic intensity.

[Effect of 50 Hz 1.8 mT sinusoidal electromagnetic fields on bone mineral density in growing rats].

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Gao, Yu-Hai; Zhou, Yan-Feng; Li, Shao-Feng; Li, Wen-Yuan; Xi, Hui-Rong; Yang, Fang-Fang; Chen, Ke-Ming

2017-12-25

To study effects of 50 Hz 1.8 mT sinusoidal electromagnetic fields (SEMFs) on bone mineral density (BMD) in SD rats. Thirty SD rats weighted(110±10) and aged 1 month were randomly divided into control group and electromagnetic field group, 15 in each group. Normal control group of 50 Hz 0 mT density and sinusoidal electromagnetic field group of 50 Hz 1.8 mT were performed respectively with 1.5 h/d and weighted weight once a week, and observed food-intake. Rats were anesthesia by intraperitoneal injection and dual energy X-ray absorptiometry were used to detect bone density of whole body, and detected bone density of femur and vertebral body. Osteocalcin and tartrate-resistant acid phosphatase 5b were detected by ELSA; weighted liver, kidney and uterus to calculate purtenance index, then detected pathologic results by HE. Compared with control group, there was no significant change in weight every week, food-intake every day; no obvious change of bone density of whole body at 2 and 4 weeks, however bone density of whole body, bone density of excised femur and vertebra were increased at 6 weeks. Expression of OC was increased, and TRACP 5b expression was decreased. No change of HE has been observed in liver, kidney and uterus and organic index. 50 Hz 1.8 mT sinusoidal electromagnetic fields could improve bone formation to decrease relevant factors of bone absorbs, to improve peak bone density of young rats, in further provide a basis for clinical research electromagnetic fields preventing osteoporosis foundation.

Evidence for a Resting State Network Abnormality in Adults Who Stutter

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Amir H. Ghaderi

2018-04-01

Full Text Available Neural network-based investigations of stuttering have begun to provide a possible integrative account for the large number of brain-based anomalies associated with stuttering. Here we used resting-state EEG to investigate functional brain networks in adults who stutter (AWS. Participants were 19 AWS and 52 age-, and gender-matched normally fluent speakers. EEGs were recorded and connectivity matrices were generated by LORETA in the theta (4–8 Hz, alpha (8–12 Hz, beta1 (12–20 Hz, and beta2 (20–30 Hz bands. Small-world propensity (SWP, shortest path, and clustering coefficients were computed for weighted graphs. Minimum spanning tree analysis was also performed and measures were compared by non-parametric permutation test. The results show that small-world topology was evident in the functional networks of all participants. Three graph indices (diameter, clustering coefficient, and shortest path exhibited significant differences between groups in the theta band and one [maximum betweenness centrality (BC] measure was significantly different between groups in the beta2 band. AWS show higher BC than control in right temporal and inferior frontal areas and lower BC in the right primary motor cortex. Abnormal functional networks during rest state suggest an anomaly of DMN activity in AWS. Furthermore, functional segregation/integration deficits in the theta network are evident in AWS. These deficits reinforce the hypothesis that there is a neural basis for abnormal executive function in AWS. Increased beta2 BC in the right speech–motor related areas confirms previous evidence that right audio–speech areas are over-activated in AWS. Decreased beta2 BC in the right primary motor cortex is discussed in relation to abnormal neural mechanisms associated with time perception in AWS.

Phenotypical and functional characterization of double-negative (CD4-CD8-) alpha beta T-cell receptor positive cells from an immunodeficient patient

DEFF Research Database (Denmark)

Illum, N; Ralfkiaer, E; Pallesen, G

1991-01-01

We have characterized CD4-CD8- double-negative (DN) alpha beta TCR+ T cells from a patient with immunodeficiency, lymphocytosis, lymphadenopathy, and hepatosplenomegaly. The majority of peripheral blood lymphocytes were DN alpha beta TCR+ T cells as evaluated by FACS and biochemical analysis...... (MoAbs) indicated a polyclonal T-cell expansion. Thymic biopsy showed normal histology, whereas lymph node biopsy samples showed altered histological and immunohistological patterns with markedly expanded paracortical areas containing the DN T cells of the same phenotype as found in peripheral blood T...

Frontal eye fields control attentional modulation of alpha and gamma oscillations in contralateral occipitoparietal cortex

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Marshall, T.R.; O'Shea, J.; Jensen, O.; Bergmann, T.O.

2015-01-01

Covertly directing visuospatial attention produces a frequency-specific modulation of neuronal oscillations in occipital and parietal cortices: anticipatory alpha (8-12 Hz) power decreases contralateral and increases ipsilateral to attention, whereas stimulus-induced gamma (>40 Hz) power is boosted

EEG Correlates of the Flow State: A Combination of Increased Frontal Theta and Moderate Frontocentral Alpha Rhythm in the Mental Arithmetic Task

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Kenji Katahira

2018-03-01

Full Text Available Flow experience is a subjective state experienced during holistic involvement in a certain activity, which has been reported to function as a factor promoting motivation, skill development, and better performance in the activity. To verify the positive effects of flow and develop a method to utilize it, the establishment of a reliable measurement of the flow state is essential. The present study utilized an electroencephalogram (EEG during an experimentally evoked flow state and examined the possibility of objective measurement of immediate flow. A total of 16 participants (10 males, 6 females participated in the experiment that employed a mental arithmetic task developed in a previous study. Post-trial self-report of the flow state and EEG during task execution were measured and compared among three conditions (Boredom, Flow, and Overload that had different levels of task difficulty. Furthermore, the correlations between subjective flow items and EEG activity were examined. As expected, the ratings on the subjective evaluation items representing the flow state were the highest in the Flow condition. Regarding the EEG data, theta activities in the frontal areas were higher in the Flow and the Overload conditions than in the Boredom condition, and alpha activity in the frontal areas and the right central area gradually increased depending on the task difficulty. These EEG activities correlated with self-reported flow experience, especially items related to the concentration on the task and task difficulty. From the results, the flow state was characterized by increased theta activities in the frontal areas and moderate alpha activities in the frontal and central areas. The former may be related to a high level of cognitive control and immersion in task, and the latter suggests that the load on the working memory was not excessive. The findings of this study suggest the possibility of distinguishing the flow state from other states using multiple

EEG Correlates of the Flow State: A Combination of Increased Frontal Theta and Moderate Frontocentral Alpha Rhythm in the Mental Arithmetic Task.

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Katahira, Kenji; Yamazaki, Yoichi; Yamaoka, Chiaki; Ozaki, Hiroaki; Nakagawa, Sayaka; Nagata, Noriko

2018-01-01

Flow experience is a subjective state experienced during holistic involvement in a certain activity, which has been reported to function as a factor promoting motivation, skill development, and better performance in the activity. To verify the positive effects of flow and develop a method to utilize it, the establishment of a reliable measurement of the flow state is essential. The present study utilized an electroencephalogram (EEG) during an experimentally evoked flow state and examined the possibility of objective measurement of immediate flow. A total of 16 participants (10 males, 6 females) participated in the experiment that employed a mental arithmetic task developed in a previous study. Post-trial self-report of the flow state and EEG during task execution were measured and compared among three conditions (Boredom, Flow, and Overload) that had different levels of task difficulty. Furthermore, the correlations between subjective flow items and EEG activity were examined. As expected, the ratings on the subjective evaluation items representing the flow state were the highest in the Flow condition. Regarding the EEG data, theta activities in the frontal areas were higher in the Flow and the Overload conditions than in the Boredom condition, and alpha activity in the frontal areas and the right central area gradually increased depending on the task difficulty. These EEG activities correlated with self-reported flow experience, especially items related to the concentration on the task and task difficulty. From the results, the flow state was characterized by increased theta activities in the frontal areas and moderate alpha activities in the frontal and central areas. The former may be related to a high level of cognitive control and immersion in task, and the latter suggests that the load on the working memory was not excessive. The findings of this study suggest the possibility of distinguishing the flow state from other states using multiple EEG activities

Insights on the neural basis of motor plasticity induced by theta burst stimulation from TMS-EEG

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VERNET, Marine; BASHIR, Shahid; YOO, Woo-Kyoung; PEREZ, Jennifer M.; NAJIB, Umer; PASCUAL-LEONE, Alvaro

2014-01-01

Transcranial magnetic stimulation (TMS) is a useful tool to induce and measure plasticity in the human brain. However, the cortical effects are generally indirectly evaluated with motor-evoked potentials (MEPs) reflective of modulation of cortico-spinal excitability. In this study, we aim to provide direct measures of cortical plasticity by combining TMS with electroencephalography (EEG). Continuous theta-burst stimulation (cTBS) was applied over the primary motor cortex (M1) of young healthy adults; and we measured modulation of (i) motor evoked-potentials (MEPs), (ii) TMS-induced EEG evoked potentials (TEPs), (iii) TMS-induced EEG synchronization and (iv) eyes-closed resting EEG. Our results show the expected cTBS-induced decrease in MEPs size, which we found to be paralleled by a modulation of a combination of TEPs. Furthermore, we found that cTBS increased the power in the theta band of eyes-closed resting EEG, whereas it decreased single-pulse TMS-induced power in the theta and alpha bands. In addition, cTBS decreased the power in the beta band of eyes-closed resting EEG, whereas it increased single-pulse TMS-induced power in the beta band. We suggest that cTBS acts by modulating the phase alignment between already active oscillators; it synchronizes low frequency (theta and/or alpha) oscillators and desynchronizes high frequency (beta) oscillators. These results provide novel insights into the cortical effects of cTBS and could be useful for exploring cTBS-induced plasticity outside of the motor cortex. PMID:23190020

Discovery of decaHz flaring in SAX J1808.4-3658

NARCIS (Netherlands)

Bult, P.

2014-01-01

We report on the discovery of strong decaHz flaring in the early decay of two out of five outbursts of the accreting millisecond X-ray pulsar SAX J1808.4-3658. The decaHz flaring switches on and, after ~3 days, off again, on a time scale of 1-2 hours. When the flaring is present, the total 0.05-10

The major surface glycoprotein of Pneumocystis carinii induces release and gene expression of interleukin-8 and tumor necrosis factor alpha in monocytes

DEFF Research Database (Denmark)

Benfield, T L; Lundgren, Bettina; Levine, S J

1997-01-01

Recent studies suggest that interleukin-8 (IL-8) and tumor necrosis factor alpha (TNF-alpha) may play a central role in host defense and pathogenesis during Pneumocystis carinii pneumonia. In order to investigate whether the major surface antigen (MSG) of human P. carinii is capable of eliciting...... the release of IL-8 and TNF-alpha, human monocytes were cultured in the presence of purified MSG. MSG-stimulated cells released significant amounts of IL-8 within 4 h, and at 20 h, cells stimulated with MSG released 45.5 +/- 9.3 ng of IL-8/ml versus 3.7 +/- 1.1 ng/ml for control cultures (P = 0.......01). In a similar fashion, MSG elicited release of TNF-alpha. Initial increases were also seen at 4 h, and at 20 h, TNF-alpha levels reached 6.4 +/- 1.1 ng/ml, compared to 0.08 +/- 0.01 ng/ml for control cultures (P alpha secretion was observed at 20 h...

Loss of balance during balance beam walking elicits a multifocal theta band electrocortical response.

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Sipp, Amy R; Gwin, Joseph T; Makeig, Scott; Ferris, Daniel P

2013-11-01

Determining the neural correlates of loss of balance during walking could lead to improved clinical assessment and treatment for individuals predisposed to falls. We used high-density electroencephalography (EEG) combined with independent component analysis (ICA) to study loss of balance during human walking. We examined 26 healthy young subjects performing heel-to-toe walking on a treadmill-mounted balance beam as well as walking on the treadmill belt (both at 0.22 m/s). ICA identified clusters of electrocortical EEG sources located in or near anterior cingulate, anterior parietal, superior dorsolateral-prefrontal, and medial sensorimotor cortex that exhibited significantly larger mean spectral power in the theta band (4-7 Hz) during walking on the balance beam compared with treadmill walking. Left and right sensorimotor cortex clusters produced significantly less power in the beta band (12-30 Hz) during walking on the balance beam compared with treadmill walking. For each source cluster, we also computed a normalized mean time/frequency spectrogram time locked to the gait cycle during loss of balance (i.e., when subjects stepped off the balance beam). All clusters except the medial sensorimotor cluster exhibited a transient increase in theta band power during loss of balance. Cluster spectrograms demonstrated that the first electrocortical indication of impending loss of balance occurred in the left sensorimotor cortex at the transition from single support to double support prior to stepping off the beam. These findings provide new insight into the neural correlates of walking balance control and could aid future studies on elderly individuals and others with balance impairments.

The Effects of 10 Hz Transcranial Alternating Current Stimulation on Audiovisual Task Switching

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Michael S. Clayton

2018-02-01

Full Text Available Neural oscillations in the alpha band (7–13 Hz are commonly associated with disengagement of visual attention. However, recent studies have also associated alpha with processes of attentional control and stability. We addressed this issue in previous experiments by delivering transcranial alternating current stimulation at 10 Hz over posterior cortex during visual tasks (alpha tACS. As this stimulation can induce reliable increases in EEG alpha power, and given that performance on each of our visual tasks was negatively associated with alpha power, we assumed that alpha tACS would reliably impair visual performance. However, alpha tACS was instead found to prevent both deteriorations and improvements in visual performance that otherwise occurred during sham & 50 Hz tACS. Alpha tACS therefore appeared to exert a stabilizing effect on visual attention. This hypothesis was tested in the current, pre-registered experiment by delivering alpha tACS during a task that required rapid switching of attention between motion, color, and auditory subtasks. We assumed that, if alpha tACS stabilizes visual attention, this stimulation should make it harder for people to switch between visual tasks, but should have little influence on transitions between auditory and visual subtasks. However, in contrast to this prediction, we observed no evidence of impairments in visuovisual vs. audiovisual switching during alpha vs. control tACS. Instead, we observed a trend-level reduction in visuoauditory switching accuracy during alpha tACS. Post-hoc analyses showed no effects of alpha tACS in response time variability, diffusion model parameters, or on performance of repeat trials. EEG analyses also showed no effects of alpha tACS on endogenous or stimulus-evoked alpha power. We discuss possible explanations for these results, as well as their broader implications for current efforts to study the roles of neural oscillations in cognition using tACS.

Music perception and imagery in EEG: Alpha band effects of task and stimulus

NARCIS (Netherlands)

Schaefer, R.S.; Vlek, R.J.; Desain, P.W.M.

2011-01-01

Previous work has shown that mental imagination of sound generally elicits an increase of alpha band activity (8-12Hz) in the electroencephalogram (EEG). In addition, alpha activity has been shown to be related to music processing. In the current study, EEG signatures were investigated for

Occipital Alpha and Gamma Oscillations Support Complementary Mechanisms for Processing Stimulus Value Associations

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Marshall, T.R.; Boer, Sebastiaan den; Cools, R.; Jensen, O.; Fallon, S.J.; Zumer, J.

2018-01-01

Selective attention is reflected neurally in changes in the power of posterior neural oscillations in the alpha (8–12 Hz) and gamma (40–100 Hz) bands. Although a neural mechanism that allows relevant information to be selectively processed has its advantages, it may lead to lucrative or dangerous

NNLOPS accurate associated HZ production with NLO decay ${\\rm{H}} \\to b\\bar{b}$ arXiv

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Astill, William; Re, Emanuele; Zanderighi, Giulia

We present a next-to-next-to-leading order (NNLO) accurate description of associated HZ production, followed by the Higgs boson decay into a pair of $b$-quarks treated at next-to-leading order (NLO), consistently matched to a parton shower (PS). The matching is achieved by performing reweighting of the $\\texttt{HZJ-MiNLO}$ events, using multi-dimensional distributions that are fully-differential in the HZ Born kinematics, to the NNLO results obtained by using the $\\texttt{MCFM-8.0}$ fixed-order calculation. Additionally we include the $gg\\to\\rm{HZ}$ contribution to the discussed process that appears at the $\\mathcal{O}(\\alpha_s^2)$. We present phenomenological results obtained for 13 TeV hadronic collisions.

Replication of elite music performance enhancement following alpha/theta neurofeedback and application to novice performance and improvisation with SMR benefits.

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Gruzelier, J H; Holmes, P; Hirst, L; Bulpin, K; Rahman, S; van Run, C; Leach, J

2014-01-01

Alpha/theta (A/T) and sensory-motor rhythm (SMR) neurofeedback were compared in university instrumentalists who were novice singers with regard to prepared and improvised instrumental and vocal performance in three music domains: creativity/musicality, technique and communication/presentation. Only A/T training enhanced advanced playing seen in all three domains by expert assessors and validated by correlations with learning indices, strongest with Creativity/Musicality as shown by Egner and Gruzelier (2003). Here A/T gains extended to novice performance - prepared vocal, improvised vocal and instrumental - and were recognised by a lay audience who judged the prepared folk songs. SMR learning correlated positively with Technical Competence and Communication in novice performance, in keeping with SMR neurofeedback's known impact on lower-order processes such as attention, working memory and psychomotor skills. The importance of validation through learning indices was emphasised in the interpretation of neurofeedback outcome. Copyright © 2013 Elsevier B.V. All rights reserved.

Hippocampal theta activity is selectively associated with contingency detection but not discrimination in rabbit discrimination-reversal eyeblink conditioning.

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Nokia, Miriam S; Wikgren, Jan

2010-04-01

The relative power of the hippocampal theta-band ( approximately 6 Hz) activity (theta ratio) is thought to reflect a distinct neural state and has been shown to affect learning rate in classical eyeblink conditioning in rabbits. We sought to determine if the theta ratio is mostly related to the detection of the contingency between the stimuli used in conditioning or also to the learning of more complex inhibitory associations when a highly demanding delay discrimination-reversal eyeblink conditioning paradigm is used. A high hippocampal theta ratio was not only associated with a fast increase in conditioned responding in general but also correlated with slow emergence of discriminative responding due to sustained responding to the conditioned stimulus not paired with an unconditioned stimulus. The results indicate that the neural state reflected by the hippocampal theta ratio is specifically linked to forming associations between stimuli rather than to the learning of inhibitory associations needed for successful discrimination. This is in line with the view that the hippocampus is responsible for contingency detection in the early phase of learning in eyeblink conditioning. (c) 2009 Wiley-Liss, Inc.

Posterior alpha oscillations reflect attentional problems in boys with Attention Deficit Hyperactivity Disorder

NARCIS (Netherlands)

Vollebregt, M.A.; Zumer, J.; Huurne, N.P. ter; Buitelaar, J.K.; Jensen, O.

2016-01-01

OBJECTIVE: This study aimed to characterize alpha modulations in children with ADHD in relation to their attentional performance. METHODS: The posterior alpha activity (8-12Hz) was measured in 30 typically developing children and 30 children with ADHD aged 7-10years, using EEG while they performed a

Intrahemispheric theta rhythm desynchronization impairs working memory.

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Alekseichuk, Ivan; Pabel, Stefanie Corinna; Antal, Andrea; Paulus, Walter

2017-01-01

There is a growing interest in large-scale connectivity as one of the crucial factors in working memory. Correlative evidence has revealed the anatomical and electrophysiological players in the working memory network, but understanding of the effective role of their connectivity remains elusive. In this double-blind, placebo-controlled study we aimed to identify the causal role of theta phase connectivity in visual-spatial working memory. The frontoparietal network was over- or de-synchronized in the anterior-posterior direction by multi-electrode, 6 Hz transcranial alternating current stimulation (tACS). A decrease in memory performance and increase in reaction time was caused by frontoparietal intrahemispheric desynchronization. According to the diffusion drift model, this originated in a lower signal-to-noise ratio, known as the drift rate index, in the memory system. The EEG analysis revealed a corresponding decrease in phase connectivity between prefrontal and parietal areas after tACS-driven desynchronization. The over-synchronization did not result in any changes in either the behavioral or electrophysiological levels in healthy participants. Taken together, we demonstrate the feasibility of manipulating multi-site large-scale networks in humans, and the disruptive effect of frontoparietal desynchronization on theta phase connectivity and visual-spatial working memory.

Continuous theta-burst stimulation combined with occupational therapy for upper limb hemiparesis after stroke: a preliminary study.

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Yamada, Naoki; Kakuda, Wataru; Kondo, Takahiro; Shimizu, Masato; Sageshima, Masashi; Mitani, Sugao; Abo, Masahiro

2014-12-01

The purpose of this study was to assess the safety, feasibility and efficacy of continuous theta-burst stimulation (cTBS) combined with intensive occupational therapy (OT) for upper limb hemiparesis after stroke. Ten patients with history of stroke and upper limb hemiparesis (age 62.0 ± 11.1 years, time since stroke 95.7 ± 70.2 months, mean ± SD) were studied. Each patient received 13 sessions, each comprising 160 s of cTBS applied to the skull on the area of the non-lesional hemisphere (using a 70-mm figure-8 coil, three pulse bursts at 50 Hz, repeated every 200 ms, i.e., 5 Hz, with total stimulation of 2,400 pulses), followed by intensive OT (comprising 120-min one-to-one training and 120-min self-training) during 15-day hospitalization. The motor function of the affected upper limb was evaluated by Fugl-Meyer Assessment (FMA) and Wolf Motor Function Test (WMFT) on the days of admission and discharge. All patients completed the 15-day protocol without any adverse effects. Treatment significantly increased the FMA score (from 46.6 ± 8.7 to 51.6 ± 8.2 points, p hemiparesis after stroke.

MILD COGNITIVE IMPAIRMENT: STRUCTURAL, METABOLICAL AND NEUROPHYSIOLOGICAL EVIDENCE OF A NOVEL EEG BIOMARKER

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Davide Vito Moretti

2015-07-01

Full Text Available Background: recent studies demonstrate that the alpha 3/alpha 2 power ratio correlates with cortical atrophy, regional hypoperfusion and memory impairment in subjects with mild cognitive impairment (MCI.Methods: evidences were reviewed in subjects with MCI who underwent EEG recording, Magnetic Resonance Imaging (MRI scans and memory evaluation. Alpha3/alpha2 power ratio (alpha2 8.9–10.9 Hz range; alpha3 10.9–12.9 Hz range, cortical thickness, linear EEG coherence and memory impairment have been evaluated in a large group of 74 patients. A subset of 27 subjects within the same group underwent also Single Photon Emission Computed Tomography (SPECT evaluation. Results: in MCI subjects with higher EEG upper/low alpha power ratio a greater temporo-parietal and hippocampal atrophy was found as well as a decrease in regional blood perfusion and memory impairment. In this group, an increase of theta oscillations is associated with a greater interhemispheric coupling between temporal areas. Conclusion: the increase of alpha3/alpha2 power ratio is a promising novel biomarker in identifying MCI subjects at risk for Alzheimer’s disease

Aberrant EEG functional connectivity and EEG power spectra in resting state post-traumatic stress disorder: a sLORETA study.

Science.gov (United States)

Imperatori, Claudio; Farina, Benedetto; Quintiliani, Maria Isabella; Onofri, Antonio; Castelli Gattinara, Paola; Lepore, Marta; Gnoni, Valentina; Mazzucchi, Edoardo; Contardi, Anna; Della Marca, Giacomo

2014-10-01

The aim of the present study was to explore the modifications of EEG power spectra and EEG connectivity of resting state (RS) condition in patients with post-traumatic stress disorder (PTSD). Seventeen patients and seventeen healthy subjects matched for age and gender were enrolled. EEG was recorded during 5min of RS. EEG analysis was conducted by means of the standardized Low Resolution Electric Tomography software (sLORETA). In power spectra analysis PTSD patients showed a widespread increase of theta activity (4.5-7.5Hz) in parietal lobes (Brodmann Area, BA 7, 4, 5, 40) and in frontal lobes (BA 6). In the connectivity analysis PTSD patients also showed increase of alpha connectivity (8-12.5Hz) between the cortical areas explored by Pz-P4 electrode. Our results could reflect the alteration of memory systems and emotional processing consistently altered in PTSD patients. Copyright © 2014 Elsevier B.V. All rights reserved.

Theta synchronization between medial prefrontal cortex and cerebellum is associated with adaptive performance of associative learning behavior

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Chen, Hao; Wang, Yi-jie; Yang, Li; Sui, Jian-feng; Hu, Zhi-an; Hu, Bo

2016-01-01

Associative learning is thought to require coordinated activities among distributed brain regions. For example, to direct behavior appropriately, the medial prefrontal cortex (mPFC) must encode and maintain sensory information and then interact with the cerebellum during trace eyeblink conditioning (TEBC), a commonly-used associative learning model. However, the mechanisms by which these two distant areas interact remain elusive. By simultaneously recording local field potential (LFP) signals from the mPFC and the cerebellum in guinea pigs undergoing TEBC, we found that theta-frequency (5.0–12.0 Hz) oscillations in the mPFC and the cerebellum became strongly synchronized following presentation of auditory conditioned stimulus. Intriguingly, the conditioned eyeblink response (CR) with adaptive timing occurred preferentially in the trials where mPFC-cerebellum theta coherence was stronger. Moreover, both the mPFC-cerebellum theta coherence and the adaptive CR performance were impaired after the disruption of endogenous orexins in the cerebellum. Finally, association of the mPFC -cerebellum theta coherence with adaptive CR performance was time-limited occurring in the early stage of associative learning. These findings suggest that the mPFC and the cerebellum may act together to contribute to the adaptive performance of associative learning behavior by means of theta synchronization. PMID:26879632

(No) time for control: Frontal theta dynamics reveal the cost of temporally guided conflict anticipation.

Science.gov (United States)

van Driel, Joram; Swart, Jennifer C; Egner, Tobias; Ridderinkhof, K Richard; Cohen, Michael X

2015-12-01

During situations of response conflict, cognitive control is characterized by prefrontal theta-band (3- to 8-Hz) activity. It has been shown that cognitive control can be triggered proactively by contextual cues that predict conflict. Here, we investigated whether a pretrial preparation interval could serve as such a cue. This would show that the temporal contingencies embedded in the task can be used to anticipate upcoming conflict. To this end, we recorded electroencephalography (EEG) from 30 human subjects while they performed a version of a Simon task in which the duration of a fixation cross between trials predicted whether the next trial would contain response conflict. Both their behavior and EEG activity showed a consistent but unexpected pattern of results: The conflict effect (increased reaction times and decreased accuracy on conflict as compared to nonconflict trials) was stronger when conflict was cued, and this was associated with stronger conflict-related midfrontal theta activity and functional connectivity. Interestingly, intervals that predicted conflict did show a pretarget increase in midfrontal theta power. These findings suggest that temporally guided expectations of conflict do heighten conflict anticipation, but also lead to less efficiently applied reactive control. We further explored this post-hoc interpretation by means of three behavioral follow-up experiments, in which we used nontemporal cues, semantically informative cues, and neutral cues. Together, this body of results suggests that the counterintuitive cost of conflict cueing may not be uniquely related to the temporal domain, but may instead be related to the implicitness and validity of the cue.

Neutron Diffraction Study On Gamma To Alpha Phase Transition In Ce0.9th0.1 Alloy

Energy Technology Data Exchange (ETDEWEB)

Lashley, Jason C1 [Los Alamos National Laboratory; Heffner, Robert H [Los Alamos National Laboratory; Llobet, A [Los Alamos National Laboratory; Darling, T W [U OF NEVADA; Jeong, I K [PUSAN NATL UNIV

2008-01-01

Comprehensive neutron diffraction measurements were performed to study the isostructural {gamma} {leftrightarrow} {alpha} phase transition in Ce{sub 0.9}Th{sub 0.1} alloy. Using Rietveld refinements, we obtained lattice and thermal parameters as a function of temperature. From the temperature slope of the thermal parameters, we determined Debye temperatures {Theta}{sup {gamma}}{sub D} = 133(1) K and {Theta}{sup {alpha}}{sub D} = 140(1) K for the {gamma} phase and the {alpha} phase, respectively. This result implies that the vibrational entropy change is not significant at the {gamma} {leftrightarrow} {alpha} transition, contrary to that from elemental Cerium [Phys. Rev. Lett. 92, 105702, 2004].

EEG Topographic Mapping of Visual and Kinesthetic Imagery in Swimmers.

Science.gov (United States)

Wilson, V E; Dikman, Z; Bird, E I; Williams, J M; Harmison, R; Shaw-Thornton, L; Schwartz, G E

2016-03-01

This study investigated differences in QEEG measures between kinesthetic and visual imagery of a 100-m swim in 36 elite competitive swimmers. Background information and post-trial checks controlled for the modality of imagery, swimming skill level, preferred imagery style, intensity of image and task equality. Measures of EEG relative magnitude in theta, low (7-9 Hz) and high alpha (8-10 Hz), and low and high beta were taken from 19 scalp sites during baseline, visual, and kinesthetic imagery. QEEG magnitudes in the low alpha band during the visual and kinesthetic conditions were attenuated from baseline in low band alpha but no changes were seen in any other bands. Swimmers produced more low alpha EEG magnitude during visual versus kinesthetic imagery. This was interpreted as the swimmers having a greater efficiency at producing visual imagery. Participants who reported a strong intensity versus a weaker feeling of the image (kinesthetic) had less low alpha magnitude, i.e., there was use of more cortical resources, but not for the visual condition. These data suggest that low band (7-9 Hz) alpha distinguishes imagery modalities from baseline, visual imagery requires less cortical resources than kinesthetic imagery, and that intense feelings of swimming requires more brain activity than less intense feelings.

Staged theta pinch experiments

International Nuclear Information System (INIS)

Linford, R.K.; Downing, J.N.; Gribble, R.F.; Jacobson, A.R.; Platts, D.A.; Thomas, K.S.

1976-01-01

Two implosion heating circuits are being experimentally tested. The principal experiment in the program is the 4.5-m-long Staged Theta Pinch (STP). It uses two relatively low energy (50kJ and 100 kJ), high voltage (125 kV) capacitor banks to produce the theta pinch plasma inside the 20 cm i.d. quartz discharge tube. A lower voltage (50 kV), higher energy (750 kJ) capacitor bank is used to contain the plasma and provide a variable amount of adiabatic compression. Because the experiment produces a higher ratio of implosion heating to compressional heating than conventional theta pinches, it should be capable of producing high temperature plasmas with a much larger ratio of plasma radius to discharge tube radius than has been possible in the past. The Resonant Heating Experiment (RHX) in its initial configuration is the same as a 0.9-m-long section of the high voltage part of the STP experiment and all the plasma results here were obtained with the experiment in that configuration. Part of the implosion bank will be removed and a low inductance crowbar added to convert it to the resonant heating configuration. (U.K.)

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation.

Science.gov (United States)

Hsu, Wan-Yu; Zanto, Theodore P; van Schouwenburg, Martine R; Gazzaley, Adam

2017-01-01

Multitasking is associated with the generation of stimulus-locked theta (4-7 Hz) oscillations arising from prefrontal cortex (PFC). Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that influences endogenous brain oscillations. Here, we investigate whether applying alternating current stimulation within the theta frequency band would affect multitasking performance, and explore tACS effects on neurophysiological measures. Brief runs of bilateral PFC theta-tACS were applied while participants were engaged in a multitasking paradigm accompanied by electroencephalography (EEG) data collection. Unlike an active control group, a tACS stimulation group showed enhancement of multitasking performance after a 90-minute session (F1,35 = 6.63, p = 0.01, ηp2 = 0.16; effect size = 0.96), coupled with significant modulation of posterior beta (13-30 Hz) activities (F1,32 = 7.66, p = 0.009, ηp2 = 0.19; effect size = 0.96). Across participant regression analyses indicated that those participants with greater increases in frontal theta, alpha and beta oscillations exhibited greater multitasking performance improvements. These results indicate frontal theta-tACS generates benefits on multitasking performance accompanied by widespread neuronal oscillatory changes, and suggests that future tACS studies with extended treatments are worth exploring as promising tools for cognitive enhancement.

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation.

Directory of Open Access Journals (Sweden)

Wan-Yu Hsu

Full Text Available Multitasking is associated with the generation of stimulus-locked theta (4-7 Hz oscillations arising from prefrontal cortex (PFC. Transcranial alternating current stimulation (tACS is a non-invasive brain stimulation technique that influences endogenous brain oscillations. Here, we investigate whether applying alternating current stimulation within the theta frequency band would affect multitasking performance, and explore tACS effects on neurophysiological measures. Brief runs of bilateral PFC theta-tACS were applied while participants were engaged in a multitasking paradigm accompanied by electroencephalography (EEG data collection. Unlike an active control group, a tACS stimulation group showed enhancement of multitasking performance after a 90-minute session (F1,35 = 6.63, p = 0.01, ηp2 = 0.16; effect size = 0.96, coupled with significant modulation of posterior beta (13-30 Hz activities (F1,32 = 7.66, p = 0.009, ηp2 = 0.19; effect size = 0.96. Across participant regression analyses indicated that those participants with greater increases in frontal theta, alpha and beta oscillations exhibited greater multitasking performance improvements. These results indicate frontal theta-tACS generates benefits on multitasking performance accompanied by widespread neuronal oscillatory changes, and suggests that future tACS studies with extended treatments are worth exploring as promising tools for cognitive enhancement.

Effectiveness of theta burst versus high-frequency repetitive transcranial magnetic stimulation in patients with depression (THREE-D): a randomised non-inferiority trial.

Science.gov (United States)

Blumberger, Daniel M; Vila-Rodriguez, Fidel; Thorpe, Kevin E; Feffer, Kfir; Noda, Yoshihiro; Giacobbe, Peter; Knyahnytska, Yuliya; Kennedy, Sidney H; Lam, Raymond W; Daskalakis, Zafiris J; Downar, Jonathan

2018-04-28

Treatment-resistant major depressive disorder is common; repetitive transcranial magnetic stimulation (rTMS) by use of high-frequency (10 Hz) left-side dorsolateral prefrontal cortex stimulation is an evidence-based treatment for this disorder. Intermittent theta burst stimulation (iTBS) is a newer form of rTMS that can be delivered in 3 min, versus 37·5 min for a standard 10 Hz treatment session. We aimed to establish the clinical effectiveness, safety, and tolerability of iTBS compared with standard 10 Hz rTMS in adults with treatment-resistant depression. In this randomised, multicentre, non-inferiority clinical trial, we recruited patients who were referred to specialty neurostimulation centres based at three Canadian university hospitals (Centre for Addiction and Mental Health and Toronto Western Hospital, Toronto, ON, and University of British Columbia Hospital, Vancouver, BC). Participants were aged 18-65 years, were diagnosed with a current treatment-resistant major depressive episode or could not tolerate at least two antidepressants in the current episode, were receiving stable antidepressant medication doses for at least 4 weeks before baseline, and had an HRSD-17 score of at least 18. Participants were randomly allocated (1:1) to treatment groups (10 Hz rTMS or iTBS) by use of a random permuted block method, with stratification by site and number of adequate trials in which the antidepressants were unsuccessful. Treatment was delivered open-label but investigators and outcome assessors were masked to treatment groups. Participants were treated with 10 Hz rTMS or iTBS to the left dorsolateral prefrontal cortex, administered on 5 days a week for 4-6 weeks. The primary outcome measure was change in 17-item Hamilton Rating Scale for Depression (HRSD-17) score, with a non-inferiority margin of 2·25 points. For the primary outcome measure, we did a per-protocol analysis of all participants who were randomly allocated to groups and who attained the primary

Just a minute meditation: Rapid voluntary conscious state shifts in long term meditators.

Science.gov (United States)

Nair, Ajay Kumar; Sasidharan, Arun; John, John P; Mehrotra, Seema; Kutty, Bindu M

2017-08-01

Meditation induces a modified state of consciousness that remains under voluntary control. Can meditators rapidly and reversibly bring about mental state changes on demand? To check, we carried out 128 channel EEG recordings on Brahma Kumaris Rajayoga meditators (36 long term: median 14240h meditation; 25 short term: 1095h) and controls (25) while they tried to switch every minute between rest and meditation states in different conditions (eyes open and closed; before and after an engaging task). Long term meditators robustly shifted states with enhanced theta power (4-8Hz) during meditation. Short term meditators had limited ability to shift between states and showed increased lower alpha power (8-10Hz) during eyes closed meditation only when pre and post task data were combined. Controls could not shift states. Thus trained beginners can reliably meditate but it takes long term practice to exercise more refined control over meditative states. Copyright © 2017 Elsevier Inc. All rights reserved.

Influence of transcranial direct current stimulation of the dorsolateral prefrontal cortex on pain related emotions: a study using electroencephalographic power spectrum analysis.

Science.gov (United States)

Maeoka, Hiroshi; Matsuo, Atsushi; Hiyamizu, Makoto; Morioka, Shu; Ando, Hiroshi

2012-03-14

Pain is a multidimensional experience with sensory-discriminative, cognitive-evaluative and affective-motivational components. Emotional factors such as unpleasantness or anxiety are known to have influence on pain in humans. The aim of this single-blinded, cross over study was to evaluate the effects of transcranial direct current stimulation (tDCS) on emotional aspects of pain in pain alleviation. Fifteen subjects (5 females, 10 males) volunteered to participate in this study. In an oddball paradigm, three categories of 20 pictures (unpleasant, neutral, and pleasant) served as rare target pictures from the International Affective Picture System (IAPS). The power of the delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-25 Hz), and gamma (30-40 Hz) frequency bands in the three categories were measured using electroencephalography during an oddball paradigm at pre- and post-anodal or sham tDCS above the left dorsolateral prefrontal cortex (DLPFC). Results showed that the beta band power was significantly increased, and the alpha band power was significantly decreased during unpleasant pictures after anodal tDCS compared with sham tDCS. Furthermore, regarding unpleasant pictures, subjective reports of Self Assessment Manikin (SAM) for emotional valence after anodal tDCS showed a significant decrease of unpleasantness. Therefore, emotional aspects of pain may be effectively alleviated by tDCS of the left DLPFC as was shown not only by subjective evaluation, but also by objective observation of cerebral neural activity. This processing may be mediated by facilitation of the descending pain inhibitory system through enhancing neural activity of the left DLPFC. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

NEBULAR ATTENUATION IN H{alpha}-SELECTED STAR-FORMING GALAXIES AT z = 0.8 FROM THE NewH{alpha} SURVEY

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Momcheva, Ivelina G. [Astronomy Department, Yale University, New Haven, CT 06511 (United States); Lee, Janice C.; Ouchi, Masami [Carnegie Observatories, Pasadena, CA 91101 (United States); Ly, Chun [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Salim, Samir [Astronomy Department, Indiana University, Bloomington, IN 47405 (United States); Dale, Daniel A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Finn, Rose [Physics Department, Siena College, Loudonville, NY 12211 (United States); Ono, Yoshiaki, E-mail: ivelina.momcheva@yale.edu [Department of Astronomy, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2013-02-01

We present measurements of the dust attenuation of H{alpha}-selected emission-line galaxies at z = 0.8 from the NewH{alpha} narrowband survey. The analysis is based on deep follow-up spectroscopy with Magellan/IMACS, which captures the strong rest-frame optical emission lines from [O II] {lambda}3727 to [O III] {lambda}5007. The spectroscopic sample used in this analysis consists of 341 confirmed H{alpha} emitters. We place constraints on the active galactic nucleus (AGN) fraction using diagnostics that can be applied at intermediate redshift. We find that at least 5% of the objects in our spectroscopic sample can be classified as AGNs and 2% are composite, i.e., powered by a combination of star formation and AGN activity. We measure the dust attenuation for individual objects from the ratios of the higher order Balmer lines. The H{beta} and H{gamma} pair of lines is detected with S/N > 5 in 55 individual objects and the H{beta} and H{delta} pair is detected in 50 individual objects. We also create stacked spectra to probe the attenuation in objects without individual detections. The median attenuation at H{alpha} based on the objects with individually detected lines is A(H{alpha}) = 0.9 {+-} 1.0 mag, in good agreement with the attenuation found in local samples of star-forming galaxies. We find that the z = 0.8 galaxies occupy a similar locus of attenuation as a function of magnitude, mass, and star formation rate (SFR) as a comparison sample drawn from the SDSS DR4. Both the results from the individual z = 0.8 galaxies and from the stacked spectra show consistency with the mass-attenuation and SFR-attenuation relations found in the local universe, indicating that these relations are also applicable at intermediate redshift.

The influence of methylphenidate on the power spectrum of ADHD children – an MEG study

Directory of Open Access Journals (Sweden)

Bauer Susanne

2005-07-01

Full Text Available Abstract Background The present study was dedicated to investigate the influence of Methylphenidate (MPH on cortical processing of children who were diagnosed with different subtypes of Attention Deficit Hyperactivity Disorder (ADHD. As all of the previous studies investigating power differences in different frequency bands have been using EEG, mostly with a relatively small number of electrodes our aim was to obtain new aspects using high density magnetoencephalography (MEG. Methods 35 children (6 female, 29 male participated in this study. Mean age was 11.7 years (± 1.92 years. 17 children were diagnosed of having an Attention-Deficit/Hyperactivity Disorder of the combined type (ADHDcom, DSM IV code 314.01; the other 18 were diagnosed for ADHD of the predominantly inattentive type (ADHDin, DSM IV code 314.0. We measured the MEG during a 5 minute resting period with a 148-channel magnetometer system (MAGNES™ 2500 WH, 4D Neuroimaging, San Diego, USA. Power values were averaged for 5 bands: Delta (D, 1.5–3.5 Hz, Theta (T, 3.5–7.5 Hz, Alpha (A, 7.5–12.5 Hz, Beta (B, 12.5–25 Hz and Global (GL, 1.5–25 Hz.. Additionally, attention was measured behaviourally using the D2 test of attention with and without medication. Results The global power of the frequency band from 1.5 to 25 Hz increased with MPH. Relative Theta was found to be higher in the left hemisphere after administration of MPH than before. A positive correlation was found between D2 test improvement and MPH-induced power changes in the Theta band over the left frontal region. A linear regression was computed and confirmed that the larger the improvement in D2 test performance, the larger the increase in Theta after MPH application. Conclusion Main effects induced by medication were found in frontal regions. Theta band activity increased over the left hemisphere after MPH application. This finding contradicts EEG results of several groups who found lower levels of Theta power

Network models provide insights into how oriens–lacunosum-moleculare and bistratified cell interactions influence the power of local hippocampal CA1 theta oscillations

Directory of Open Access Journals (Sweden)

Katie A Ferguson

2015-08-01

Full Text Available Hippocampal theta is a 4-12 Hz rhythm associated with episodic memory, and although it has been studied extensively, the cellular mechanisms underlying its generation are unclear. The complex interactions between different interneuron types, such as those between oriens--lacunosum-moleculare (OLM interneurons and bistratified cells (BiCs, make their contribution to network rhythms difficult to determine experimentally. We created network models that are tied to experimental work at both cellular and network levels to explore how these interneuron interactions affect the power of local oscillations. Our cellular models were constrained with properties from patch clamp recordings in the CA1 region of an intact hippocampus preparation in vitro. Our network models are composed of three different types of interneurons: parvalbumin-positive (PV+ basket and axo-axonic cells (BC/AACs, PV+ BiCs, and somatostatin-positive OLM cells. Also included is a spatially extended pyramidal cell model to allow for a simplified local field potential representation, as well as experimentally-constrained, theta frequency synaptic inputs to the interneurons. The network size, connectivity, and synaptic properties were constrained with experimental data. To determine how the interactions between OLM cells and BiCs could affect local theta power, we explored a number of OLM-BiC connections and connection strengths.We found that our models operate in regimes in which OLM cells minimally or strongly affected the power of network theta oscillations due to balances that, respectively, allow compensatory effects or not. Inactivation of OLM cells could result in no change or even an increase in theta power. We predict that the dis-inhibitory effect of OLM cells to BiCs to pyramidal cell interactions plays a critical role in the power of network theta oscillations. Our network models reveal a dynamic interplay between different classes of interneurons in influencing local theta

Kinesthetic motor imagery training modulates frontal midline theta during imagination of a dart throw.

Science.gov (United States)

Weber, E; Doppelmayr, M

2016-12-01

Motor imagery (MI) is a frequently used and effective method for motor learning in sports as well as in other domains. Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) studies indicated that experts within a certain sport exhibit a more pronounced brain activity during MI as compared to novices. Similar to the execution, during MI the motor sequence has to be planned. Thus, the frontal attentional system, in part represented by the frontal midline theta (4-7Hz), is closely related to these processes and presumably plays a major role in MI as well. In this study, a MI dart training and its impact on frontal midline theta activity (fmt) during MI are examined. 53 healthy subjects with no prior dart experience were randomly allocated to a kinesthetic training group (KinVis) or to a control group (Control). Both groups performed 15 training sessions. While in the KinVis group dart throwing was accompanied by MI, the Control group trained without MI. Dart performance and fmt activity during MI within the first and the 15th session were compared. As expected, the performance increase was more pronounced in the KinVis group. Furthermore, frontal theta amplitude was significantly increased in the KinVis group during MI in the 15th training session as compared to the baseline. These results confirm the effectivity of MI. The enhanced fmt activity in the KinVis group can be interpreted as a better allocation of the requested resources in the frontal attentional network after MI. Copyright © 2016 Elsevier B.V. All rights reserved.

Neural mechanisms of mismatch negativity dysfunction in schizophrenia.

Science.gov (United States)

Lee, M; Sehatpour, P; Hoptman, M J; Lakatos, P; Dias, E C; Kantrowitz, J T; Martinez, A M; Javitt, D C

2017-11-01

Schizophrenia is associated with cognitive deficits that reflect impaired cortical information processing. Mismatch negativity (MMN) indexes pre-attentive information processing dysfunction at the level of primary auditory cortex. This study investigates mechanisms underlying MMN impairments in schizophrenia using event-related potential, event-related spectral decomposition (ERSP) and resting state functional connectivity (rsfcMRI) approaches. For this study, MMN data to frequency, intensity and duration-deviants were analyzed from 69 schizophrenia patients and 38 healthy controls. rsfcMRI was obtained from a subsample of 38 patients and 23 controls. As expected, schizophrenia patients showed highly significant, large effect size (P=0.0004, d=1.0) deficits in MMN generation across deviant types. In ERSP analyses, responses to deviants occurred primarily the theta (4-7 Hz) frequency range consistent with distributed corticocortical processing, whereas responses to standards occurred primarily in alpha (8-12 Hz) range consistent with known frequencies of thalamocortical activation. Independent deficits in schizophrenia were observed in both the theta response to deviants (P=0.021) and the alpha-response to standards (P=0.003). At the single-trial level, differential patterns of response were observed for frequency vs duration/intensity deviants, along with At the network level, MMN deficits engaged canonical somatomotor, ventral attention and default networks, with a differential pattern of engagement across deviant types (Pschizophrenia. In addition, differences in ERSP and rsfcMRI profiles across deviant types suggest potential differential engagement of underlying generator mechanisms.

Alpha decay and nuclear deformation: the case for favoured alpha transitions of even-even emitters

Energy Technology Data Exchange (ETDEWEB)

Garcia, F. [Universidade Estadual de Santa Cruz, Ilheus, BA (Brazil). Dept. de Ciencias Exatas e Tecnologicas; Rodriguez, O.; Guzman, F. [Instituto Superior de Ciencias y Tecnologia Nucleares (ISCTN), La Habana (Cuba); Goncalves, M. [Instituto de Radioprotecao e Dosimetria IRD/CNEN, Rio de Janeiro, RJ (Brazil); Duarte, S.B.; Tavares, O.A.P. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). E-mail: sbd@cbpf.br

2000-02-01

Alpha-decay half-life for ground-state transitions of 174 even-even alpha emitters has been calculated from a simple, Gamow-like model in which the quadrupole deformation of the product nucleus (assumed to have an ellipsoidal shape) is taken into account. The assumption made is that before tunneling through a purely Coulomb potential barrier the two-body system oscillates isotropically, thus giving rise to an equivalent, average polar direction {theta} (referred to the symmetry axis of the ellipsoid) for alpha emission. It is shown that the experimental half-life data are much better reproduced by the present description than in the spherical-shaped approximation for the daughter nucleus. (author)

Symmetry hierarchies and radiative corrections in the grand unified model SU(8)/sub L/ x SU(8)/sub R/

International Nuclear Information System (INIS)

Pirogov, Y.F.

1982-01-01

In the SU(8)/sub L/ x SU(8)/sub R/ model of precocious chiral unification, radiative corrections for the effective parameters sin 2 theta/sub W/(μ) and α(μ) are calculated in the one-loop approximation, neglecting contributions of the Higgs fields, and the unification mass M 8 is determined in the presence of a hierarchy of intermediate symmetries. It is shown that a natural hierarchy exists which leads to a decrease in sin 2 theta/sub W/(M/sub W/L) down to the value sin 2 theta/sub W/ = (1/5)--(1/4) together with a decrease in M 8 down to M 8 = 10 6 --10 7 GeV in comparison with the values in the absence of a hierarchy

Search for $\\Theta^{++}$ Pentaquarks in the Exclusive Reaction $\\gamma p\\to K^+K^-p$

Energy Technology Data Exchange (ETDEWEB)

V. Kubarovsky; Marco Battaglieri; Raffaella De Vita; John Goett; Lei Guo; Gordon Mutchler; Paul Stoler; Dennis Weygand; Pawel Ambrozewicz; Marco Anghinolfi; Gegham Asryan; Harutyun AVAKIAN; Harutyun Avakian; H. Bagdasaryan; Nathan Baillie; Jacques Ball; Nathan Baltzell; V. Batourine; Ivan Bedlinski; Ivan Bedlinskiy; Matthew Bellis; Nawal Benmouna; Barry Berman; Angela Biselli; Sylvain Bouchigny; Sergey Boyarinov; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Shifeng Chen; Eric Clinton; Philip Cole; Patrick Collins; Philip Coltharp; Donald Crabb; Hall Crannell; Volker Crede; John Cummings; Rita De Masi; Daniel Dale; Enzo De Sanctis; Pavel Degtiarenko; Alexandre Deur; Kahanawita Dharmawardane; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Latifa Elouadrhiri; Paul Eugenio; Gleb Fedotov; Herbert Funsten; Marianna Gabrielyan; Liping Gan; Michel Garcon; Ashot Gasparian; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; Oleksandr Glamazdin; John Goetz; Evgueni Golovatch; Atilla Gonenc; Christopher Gordon; Ralf Gothe; Keith Griffioen; Michel Guidal; Nevzat Guler; Vardan Gyurjyan; Cynthia Hadjidakis; Kawtar Hafidi; Rafael Hakobyan; John Hardie; F. Hersman; Kenneth Hicks; Ishaq Hleiqawi; Maurik Holtrop; Charles Hyde-Wright; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Eugeny Isupov; Mark Ito; David Jenkins; Hyon-Suk Jo; Kyungseon Joo; Henry Juengst; James Kellie; Mahbubul Khandaker; Wooyoung Kim; Franz Klein; Friedrich Klein; Alexei Klimenko; Mikhail Kossov; Laird Kramer; Joachim Kuhn; Sebastian Kuhn; Sergey Kuleshov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; David Lawrence; Tsung-shung Lee; Ji Li; Kenneth Livingston; Hai-jiang Lu; Marion MacCormick; Nikolai Markov; Bryan McKinnon; Bernhard Mecking; Joseph Melone; Mac Mestayer; Curtis Meyer; Tsutomu Mibe; Konstantin Mikhaylov; Ralph Minehart; Marco Mirazita; Rory Miskimen; Vasiliy Mochalov; Viktor Mokeev; Ludyvine Morand; Steven Morrow; Maryam Moteabbed; Pawel Nadel-Turonski; Itaru Nakagawa; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Mikhail Osipenko; Alexander Ostrovidov; Kijun Park; Evgueni Pasyuk; Craig Paterson; Joshua Pierce; Nikolay Pivnyuk; Dinko Pocanic; Oleg Pogorelko; Sergey Pozdnyakov; John Price; Yelena Prok; Dan Protopopescu; Brian Raue; Gregory Riccardi; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; Franck Sabatie; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Youri Sharabian; Nikolay Shvedunov; Elton Smith; Lee Smith; Daniel Sober; Aleksey Stavinskiy; Samuel Stepanyan; Stepan Stepanyan; Burnham Stokes; Igor Strakovski; Steffen Strauch; Mauro Taiuti; David Tedeschi; Aram Teymurazyan; Ulrike Thoma; Avtandil Tkabladze; Svyatoslav Tkachenko; Luminita Todor; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Lawrence Weinstein; Michael Williams; Elliott Wolin; Michael Wood; Amrit Yegneswaran; Lorenzo Zana; Jixie Zhang; Bo Zhao

2006-04-28

The reaction {gamma}p {yields} K{sup +}K{sup -}p was studied at Jefferson Lab with photon energies from 1.8 to 3.8 GeV using a tagged photon beam. The goal was to search for a {Theta}{sup ++} pentaquark, a narrow doubly charged baryon state having strangeness S = +1 and isospin I = 1, in the pK{sup +} invariant mass spectrum. No statistically significant evidence of a {Theta}{sup ++} was found. Upper limits on the total and differential production cross section for the reaction {gamma}p {yields} K{sup -}{Theta}{sup ++} were obtained in the mass range from 1.5 to 2.0 GeV/c{sup 2}, with an upper limit of about 0.15 nb, 95% C.L. for a narrow resonance with a mass M{sub {Theta}{sup ++}} = 1.54 GeV/c{sup 2}. This result places a very stringent upper limit on the {Theta}{sup ++} width.

Correlation of EEG with neuropsychological status in children with epilepsy.

Science.gov (United States)

Hsu, David A; Rayer, Katherine; Jackson, Daren C; Stafstrom, Carl E; Hsu, Murielle; Ferrazzano, Peter A; Dabbs, Kevin; Worrell, Gregory A; Jones, Jana E; Hermann, Bruce P

2016-02-01

To determine correlations of the EEG frequency spectrum with neuropsychological status in children with idiopathic epilepsy. Forty-six children ages 8-18 years old with idiopathic epilepsy were retrospectively identified and analyzed for correlations between EEG spectra and neuropsychological status using multivariate linear regression. In addition, the theta/beta ratio, which has been suggested as a clinically useful EEG marker of attention-deficit hyperactivity disorder (ADHD), and an EEG spike count were calculated for each subject. Neuropsychological status was highly correlated with posterior alpha (8-15 Hz) EEG activity in a complex way, with both positive and negative correlations at lower and higher alpha frequency sub-bands for each cognitive task in a pattern that depends on the specific cognitive task. In addition, the theta/beta ratio was a specific but insensitive indicator of ADHD status in children with epilepsy; most children both with and without epilepsy have normal theta/beta ratios. The spike count showed no correlations with neuropsychological status. (1) The alpha rhythm may have at least two sub-bands which serve different purposes. (2) The theta/beta ratio is not a sensitive indicator of ADHD status in children with epilepsy. (3) The EEG frequency spectrum correlates more robustly with neuropsychological status than spike count analysis in children with idiopathic epilepsy. (1) The role of posterior alpha rhythms in cognition is complex and can be overlooked if EEG spectral resolution is too coarse or if neuropsychological status is assessed too narrowly. (2) ADHD in children with idiopathic epilepsy may involve different mechanisms from those in children without epilepsy. (3) Reliable correlations with neuropsychological status require longer EEG samples when using spike count analysis than when using frequency spectra. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights

Synthesis and antimicrobial evaluation of new 3-alkyl/aryl-2-[((alpha,alpha-diphenyl-alpha-hydroxy)acetyl)hydrazono]-5-methyl-4-thiazolidinones.

Science.gov (United States)

Güzeldemirci, Nuray Ulusoy; Ilhan, Eser; Küçükbasmaci, Omer; Satana, Dilek

2010-01-01

New 4-thiazolidinone derivatives of benzilic acid (alpha,alpha-diphenyl-alpha-hydroxyacetic acid) have been synthesized and evaluated for antibacterial and antifungal activities. The reaction of 1- (alpha,alpha-diphenyl-alpha-hydroxy)acetyl-4-alkyl/arylthiosemicarbazides with ethyl 2-bromopropionate gave 3-alkyl/aryl-2-[((alpha,alpha-diphenyl-alpha-hydroxy)acetyl)hydrazono]-5-methyl-4-thiazolidinone derivatives. Their antibacterial and antifungal activities were evaluated against S. aureus ATCC 29213, P. aeruginosa ATCC 27853, E. coli ATCC 25922, C. albicans ATCC 10231, C. parapsilosis ATCC 22019, C. krusei ATCC 6258, T. mentagrophytes var. erinacei NCPF 375, M. gypseum NCPF 580 and T. tonsurans NCPF 245. 3e, 3f, 3g and 3h showed the highest antibacterial activity. Particularly 3a and 3e showed the highest antifungal activities against C. parapsilosis ATCC 22019, T. tonsurans NCPF 245 and M. gypseum NCPF 580.

{theta}-Compactness in L-topological spaces

Energy Technology Data Exchange (ETDEWEB)

Hanafy, I.M. [Department of Mathematics, Faculty of Education, Suez Canal University, El-Arish (Egypt)], E-mail: ihanafy@hotmail.com

2009-12-15

Recently, El-Naschie has shown that the notion of fuzzy topology may be relevant to quantum particle physics in connection with string theory and e{sup {infinity}} theory. In 2005, Caldas and Jafari have introduced {theta}-compact fuzzy topological spaces. In this paper, the concepts of{theta}-compactness, countable{theta}-compactness and the{theta}-Lindeloef property are introduced and studied in L-topological spaces, where L is a complete de Morgan algebra. They are defined by means of{theta}-openL-sets and their inequalities. They does not rely on the structure of basis lattice L and no distributivity in L is required. They can also be characterized by{theta}-closedL-sets and their inequalities. When L is a completely de Morgan algebra, their many characterizations are presented.

Atmospheric, long baseline, and reactor neutrino data constraints on theta_{13}.

Science.gov (United States)

Roa, J E; Latimer, D C; Ernst, D J

2009-08-07

An atmospheric neutrino oscillation tool that uses full three-neutrino oscillation probabilities and a full three-neutrino treatment of the Mikheyev-Smirnov-Wolfenstein effect, together with an analysis of the K2K, MINOS, and CHOOZ data, is used to examine the bounds on theta_{13}. The recent, more finely binned, Super-K atmospheric data are employed. For L/E_{nu} greater, similar 10;{4} km/GeV, we previously found significant linear in theta_{13} terms. This analysis finds theta_{13} bounded from above by the atmospheric data while bounded from below by CHOOZ. The origin of this result arises from data in the previously mentioned very long baseline region; here, matter effects conspire with terms linear in theta_{13} to produce asymmetric bounds on theta_{13}. Assuming CP conservation, we find theta_{13} = -0.07_{-0.11};{+0.18} (90% C.L.).

Did You Listen to the Beat? Auditory Steady-State Responses in the Human Electroencephalogram at 4 and 7 Hz Modulation Rates Reflect Selective Attention.

Science.gov (United States)

Jaeger, Manuela; Bleichner, Martin G; Bauer, Anna-Katharina R; Mirkovic, Bojana; Debener, Stefan

2018-02-27

The acoustic envelope of human speech correlates with the syllabic rate (4-8 Hz) and carries important information for intelligibility, which is typically compromised in multi-talker, noisy environments. In order to better understand the dynamics of selective auditory attention to low frequency modulated sound sources, we conducted a two-stream auditory steady-state response (ASSR) selective attention electroencephalogram (EEG) study. The two streams consisted of 4 and 7 Hz amplitude and frequency modulated sounds presented from the left and right side. One of two streams had to be attended while the other had to be ignored. The attended stream always contained a target, allowing for the behavioral confirmation of the attention manipulation. EEG ASSR power analysis revealed a significant increase in 7 Hz power for the attend compared to the ignore conditions. There was no significant difference in 4 Hz power when the 4 Hz stream had to be attended compared to when it had to be ignored. This lack of 4 Hz attention modulation could be explained by a distracting effect of a third frequency at 3 Hz (beat frequency) perceivable when the 4 and 7 Hz streams are presented simultaneously. Taken together our results show that low frequency modulations at syllabic rate are modulated by selective spatial attention. Whether attention effects act as enhancement of the attended stream or suppression of to be ignored stream may depend on how well auditory streams can be segregated.

Natural Translating Locomotion Modulates Cortical Activity at Action Observation

Directory of Open Access Journals (Sweden)

Thierry Pozzo

2017-11-01

Full Text Available The present study verified if the translational component of locomotion modulated cortical activity recorded at action observation. Previous studies focusing on visual processing of biological motion mainly presented point light walker that were fixed on a spot, thus removing the net translation toward a goal that yet remains a critical feature of locomotor behavior. We hypothesized that if biological motion recognition relies on the transformation of seeing in doing and its expected sensory consequences, a significant effect of translation compared to centered displays on sensorimotor cortical activity is expected. To this aim, we explored whether EEG activity in the theta (4–8 Hz, alpha (8–12 Hz, beta 1 (14–20 Hz and beta 2 (20–32 Hz frequency bands exhibited selectivity as participants viewed four types of stimuli: a centered walker, a centered scrambled, a translating walker and a translating scrambled. We found higher theta synchronizations for observed stimulus with familiar shape. Higher power decreases in the beta 1 and beta 2 bands, indicating a stronger motor resonance was elicited by translating compared to centered stimuli. Finally, beta bands modulation in Superior Parietal areas showed that the translational component of locomotion induced greater motor resonance than human shape. Using a Multinomial Logistic Regression classifier we found that Dorsal-Parietal and Inferior-Frontal regions of interest (ROIs, constituting the core of action-observation system, were the only areas capable to discriminate all the four conditions, as reflected by beta activities. Our findings suggest that the embodiment elicited by an observed scenario is strongly mediated by horizontal body displacement.

Co-receptor choice by V alpha14i NKT cells is driven by Th-POK expression rather than avoidance of CD8-mediated negative selection.

Science.gov (United States)

Engel, Isaac; Hammond, Kirsten; Sullivan, Barbara A; He, Xi; Taniuchi, Ichiro; Kappes, Dietmar; Kronenberg, Mitchell

2010-05-10

Mouse natural killer T (NKT) cells with an invariant V alpha14-J alpha18 rearrangement (V alpha14 invariant [V alpha14i] NKT cells) are either CD4(+)CD8(-) or CD4(-)CD8(-). Because transgenic mice with forced CD8 expression in all T cells exhibited a profound NKT cell deficit, the absence of CD8 has been attributed to negative selection. We now present evidence that CD8 does not serve as a coreceptor for CD1d recognition and that the defect in development in CD8 transgene homozygous mice is the result of a reduction in secondary T cell receptor alpha rearrangements. Thymocytes from mice hemizygous for the CD8 transgene have a less severe rearrangement defect and have functional CD8(+) V alpha14i NKT cells. Furthermore, we demonstrate that the transcription factor Th, Poxviruses and Zinc finger, and Krüppel family (Th-POK) is expressed by V alpha14i NKT cells throughout their differentiation and is necessary both to silence CD8 expression and for the functional maturity of V alpha14i NKT cells. We therefore suggest that Th-POK expression is required for the normal development of V alpha14i NKT cells and that the absence of CD8 expression by these cells is a by-product of such expression, as opposed to the result of negative selection of CD8-expressing V alpha14i NKT cells.

Attention and Working Memory-Related EEG Markers of Subtle Cognitive Deterioration in Healthy Elderly Individuals.

Science.gov (United States)

Deiber, Marie-Pierre; Meziane, Hadj Boumediene; Hasler, Roland; Rodriguez, Cristelle; Toma, Simona; Ackermann, Marine; Herrmann, François; Giannakopoulos, Panteleimon

2015-01-01

Future treatments of Alzheimer's disease need the identification of cases at high risk at the preclinical stage of the disease before the development of irreversible structural damage. We investigated here whether subtle cognitive deterioration in a population of healthy elderly individuals could be predicted by EEG signals at baseline under cognitive activation. Continuous EEG was recorded in 97 elderly control subjects and 45 age-matched mild cognitive impairment (MCI) cases during a simple attentional and a 2-back working memory task. Upon 18-month neuropsychological follow-up, the final sample included 55 stable (sCON) and 42 deteriorated (dCON) controls. We examined the P1, N1, P3, and PNwm event-related components as well as the oscillatory activities in the theta (4-7 Hz), alpha (8-13 Hz), and beta (14-25 Hz) frequency ranges (ERD/ERS: event-related desynchronization/synchronization, and ITC: inter-trial coherence). Behavioral performance, P1, and N1 components were comparable in all groups. The P3, PNwm, and all oscillatory activity indices were altered in MCI cases compared to controls. Only three EEG indices distinguished the two control groups: alpha and beta ERD (dCON >  sCON) and beta ITC (dCON memory processes but mostly affects attention, resulting in an enhanced recruitment of attentional resources. In addition, cognitive decline alters neural firing synchronization at high frequencies (14-25 Hz) at early stages, and possibly affects lower frequencies (4-13 Hz) only at more severe stages.

Structure of the T cell receptor in a Ti alpha V beta 2, alpha V beta 8-positive T cell line

DEFF Research Database (Denmark)

Hou, X; Dietrich, J; Kuhlmann, J

1994-01-01

not known; however, it has been suggested that each TcR contains two Ti dimers. To gain insight into the structure of the TcR we constructed a Ti alpha V beta 2, alpha V beta 8-positive T cell line which expressed the endogenous human TiV beta 8 and the transfected mouse TiV beta 2 both in association......The T cell receptor (TcR) is composed of at least six different polypeptide chains consisting of the clonotypic Ti heterodimer (Ti alpha beta or Ti gamma delta) and the noncovalently associated CD3 chains (CD3 gamma delta epsilon zeta). The exact number of subunits constituting the TcR is still...... with the endogenous Ti alpha and CD3 chains at the cell surface. Preclearing experiments with radioiodinated cell lysate prepared with digitonin lysis buffer demonstrated that depleting the lysate of Ti alpha V beta 8 by immunoprecipitation with anti V beta 8 monoclonal antibody (mAb) did not reduce the amount of Ti...

Tracking EEG changes in response to alpha and beta binaural beats.

Science.gov (United States)

Vernon, D; Peryer, G; Louch, J; Shaw, M

2014-07-01

A binaural beat can be produced by presenting two tones of a differing frequency, one to each ear. Such auditory stimulation has been suggested to influence behaviour and cognition via the process of cortical entrainment. However, research so far has only shown the frequency following responses in the traditional EEG frequency ranges of delta, theta and gamma. Hence a primary aim of this research was to ascertain whether it would be possible to produce clear changes in the EEG in either the alpha or beta frequency ranges. Such changes, if possible, would have a number of important implications as well as potential applications. A secondary goal was to track any observable changes in the EEG throughout the entrainment epoch to gain some insight into the nature of the entrainment effects on any changes in an effort to identify more effective entrainment regimes. Twenty two healthy participants were recruited and randomly allocated to one of two groups, each of which was exposed to a distinct binaural beat frequency for ten 1-minute epochs. The first group listened to an alpha binaural beat of 10 Hz and the second to a beta binaural beat of 20 Hz. EEG was recorded from the left and right temporal regions during pre-exposure baselines, stimulus exposure epochs and post-exposure baselines. Analysis of changes in broad-band and narrow-band amplitudes, and frequency showed no effect of binaural beat frequency eliciting a frequency following effect in the EEG. Possible mediating factors are discussed and a number of recommendations are made regarding future studies, exploring entrainment effects from a binaural beat presentation. Copyright © 2012 Elsevier B.V. All rights reserved.

Active auditory experience in infancy promotes brain plasticity in Theta and Gamma oscillations

Directory of Open Access Journals (Sweden)

Gabriella Musacchia

2017-08-01

Full Text Available Language acquisition in infants is driven by on-going neural plasticity that is acutely sensitive to environmental acoustic cues. Recent studies showed that attention-based experience with non-linguistic, temporally-modulated auditory stimuli sharpens cortical responses. A previous ERP study from this laboratory showed that interactive auditory experience via behavior-based feedback (AEx, over a 6-week period from 4- to 7-months-of-age, confers a processing advantage, compared to passive auditory exposure (PEx or maturation alone (Naïve Control, NC. Here, we provide a follow-up investigation of the underlying neural oscillatory patterns in these three groups. In AEx infants, Standard stimuli with invariant frequency (STD elicited greater Theta-band (4–6 Hz activity in Right Auditory Cortex (RAC, as compared to NC infants, and Deviant stimuli with rapid frequency change (DEV elicited larger responses in Left Auditory Cortex (LAC. PEx and NC counterparts showed less-mature bilateral patterns. AEx infants also displayed stronger Gamma (33–37 Hz activity in the LAC during DEV discrimination, compared to NCs, while NC and PEx groups demonstrated bilateral activity in this band, if at all. This suggests that interactive acoustic experience with non-linguistic stimuli can promote a distinct, robust and precise cortical pattern during rapid auditory processing, perhaps reflecting mechanisms that support fine-tuning of early acoustic mapping.

Identification of 4,5-didemethyl-4-O-alpha-D-glucopyranosylsimmondsin and pinitol alpha-D-galactosides in jojoba seed meal (Simmondsia chinensis).

Science.gov (United States)

Van Boven, M; Leyssen, T; Busson, R; Holser, R; Cokelaere, M; Flo, G; Decuypere, E

2001-09-01

The isolation and identification of two pinitol alpha-D-galactosides from jojoba meal are described. The products were isolated by a combination of preparative HPLC on silica gel and TLC on amino silica gel and were identified by MS, NMR spectroscopy, and chemical derivatization as 5-O-(alpha-D-galactopyranosyl)-3-O-methyl-D-chiro-inositol or 5-alpha-D-galactopyranosyl-D-pinitol and 2-O-(alpha-D-galactopyranosyl)-3-O-methyl-D-chiro-inositol or 2-alpha-D-galactopyranosyl-D-pinitol. The same preparative HPLC method on silica gel allowed a new simmondsin derivative to be isolated and identified as 4,5-didemethyl-4-O-alpha-D-glucopyranosylsimmondsin mainly by NMR spectroscopy and high-resolution mass spectrometry.

Effects of 10 Hz and 20 Hz Transcranial Alternating Current Stimulation on Automatic Motor Control.

Science.gov (United States)

Cappon, Davide; D'Ostilio, Kevin; Garraux, Gaëtan; Rothwell, John; Bisiacchi, Patrizia

2016-01-01

In a masked prime choice reaction task, presentation of a compatible prime increases the reaction time to the following imperative stimulus if the interval between mask and prime is around 80-250 ms. This is thought to be due to automatic suppression of the motor plan evoked by the prime, which delays reaction to the imperative stimulus. Oscillatory activity in motor networks around the beta frequency range of 20 Hz is important in suppression of movement. Transcranial alternating current at 20 Hz may be able to drive oscillations in the beta range. To investigate whether transcranial alternating current stimulation (tACS) at 20 Hz would increase automatic inhibition in a masked prime task. As a control we used 10 Hz tACS. Stimulation was delivered at alpha (10 Hz) and beta (20 Hz) frequency over the supplementary motor area and the primary motor cortex (simultaneous tACS of SMA-M1), which are part of the BG-cortical motor loop, during the execution of the subliminal masked prime left/right choice reaction task. We measured the effects on reaction times. Corticospinal excitability was assessed by measuring the amplitude of motor evoked potentials (MEPs) evoked in the first dorsal interosseous muscle by transcranial magnetic stimulation (TMS) over M1. The 10 and 20-Hz tACS over SMA-M1 had different effects on automatic inhibition. The 20 Hz tACS increased the duration of automatic inhibition whereas it was decreased by 10 Hz tACS. Neurophysiologically, 20 Hz tACS reduced the amplitude of MEPs evoked from M1, whereas there was no change after 10 Hz tACS. Automatic mechanisms of motor inhibition can be modulated by tACS over motor areas of cortex. tACS may be a useful additional tool to investigate the causal links between endogenous brain oscillations and specific cognitive processes. Copyright © 2016 Elsevier Inc. All rights reserved.

Identification of NR4A2 as a transcriptional activator of IL-8 expression in human inflammatory arthritis.

LENUS (Irish Health Repository)

Aherne, Carol M

2009-10-01

Expression of the orphan nuclear receptor NR4A2 is controlled by pro-inflammatory mediators, suggesting that NR4A2 may contribute to pathological processes in the inflammatory lesion. This study identifies the chemoattractant protein, interleukin 8 (IL-8\\/CXCL8), as a molecular target of NR4A2 in human inflammatory arthritis and examines the mechanism through which NR4A2 modulates IL-8 expression. In TNF-alpha-activated human synoviocyte cells, enhanced expression of IL-8 mRNA and protein correspond to temporal changes in NR4A2 transcription and nuclear distribution. Ectopic expression of NR4A2 leads to robust changes in endogenous IL-8 mRNA levels and co-treatment with TNF-alpha results in significant (p<0.001) secretion of IL-8 protein. Transcriptional effects of NR4A2 on the human IL-8 promoter are enhanced in the presence of TNF-alpha, suggesting molecular crosstalk between TNF-alpha signalling and NR4A2. A dominant negative IkappaB kinase antagonizes the combined effects of NR4A2 and TNF-alpha on IL-8 promoter activity. Co-expression of NR4A2 and the p65 subunit of NF-kappaB enhances IL-8 transcription and functional studies indicate that transactivation occurs independently of NR4A2 binding to DNA or heterodimerization with additional nuclear receptors. The IL-8 minimal promoter region is sufficient to support NR4A2 and NF-kappaB\\/p65 co-operative activity and NR4A2 can interact with NF-kappaB\\/p65 on a 39bp sequence within this region. In patients treated with methotrexate for active inflammatory arthritis, a reduction in NR4A2 synovial tissue levels correlate significantly (n=10, r=0.73, p=0.002) with changes in IL-8 expression. Collectively, these data delineate an important role for NR4A2 in modulating IL-8 expression and reveal novel transcriptional responses to TNF-alpha in human inflammatory joint disease.

LTPF: a linear theta-pinch neutron source

International Nuclear Information System (INIS)

Ellis, W.R.

1975-07-01

The linear theta pinch is optimized with respect to maximum neutron current on a sample located between the discharge tube and the compression coil wall. Emphasis throughout is placed on physics and technology considerations which govern the choice of parameters. Technological demands are (hopefully) kept to a minimum. Two ''point designs'' are developed which are distinguished by their compressional magnetic field (i.e., coil current) wave-forms: one is sinusoidal and continuous, the other trapezoidal and pulsed intermittently. Both point designs give an average neutron current of approximately 5 x 10 13 n/cm 2 /s. Both devices are characterized by short lengths (approximately 1 m), rapid cycling (2 to 30 kHz), and magnetic mirrors (2 to 5:1) at the ends. A crucial item is the power supply, which is discussed in detail. (U.S.)

Modification of EEG power spectra and EEG connectivity in autobiographical memory: a sLORETA study.

Science.gov (United States)

Imperatori, Claudio; Brunetti, Riccardo; Farina, Benedetto; Speranza, Anna Maria; Losurdo, Anna; Testani, Elisa; Contardi, Anna; Della Marca, Giacomo

2014-08-01

The aim of the present study was to explore the modifications of scalp EEG power spectra and EEG connectivity during the autobiographical memory test (AM-T) and during the retrieval of an autobiographical event (the high school final examination, Task 2). Seventeen healthy volunteers were enrolled (9 women and 8 men, mean age 23.4 ± 2.8 years, range 19-30). EEG was recorded at baseline and while performing the autobiographical memory (AM) tasks, by means of 19 surface electrodes and a nasopharyngeal electrode. EEG analysis was conducted by means of the standardized LOw Resolution Electric Tomography (sLORETA) software. Power spectra and lagged EEG coherence were compared between EEG acquired during the memory tasks and baseline recording. The frequency bands considered were as follows: delta (0.5-4 Hz); theta (4.5-7.5 Hz); alpha (8-12.5 Hz); beta1 (13-17.5 Hz); beta2 (18-30 Hz); gamma (30.5-60 Hz). During AM-T, we observed a significant delta power increase in left frontal and midline cortices (T = 3.554; p < 0.05) and increased EEG connectivity in delta band in prefrontal, temporal, parietal, and occipital areas, and for gamma bands in the left temporo-parietal regions (T = 4.154; p < 0.05). In Task 2, we measured an increased power in the gamma band located in the left posterior midline areas (T = 3.960; p < 0.05) and a significant increase in delta band connectivity in the prefrontal, temporal, parietal, and occipital areas, and in the gamma band involving right temporo-parietal areas (T = 4.579; p < 0.05). These results indicate that AM retrieval engages in a complex network which is mediated by both low- (delta) and high-frequency (gamma) EEG bands.

Traveling Theta Waves in the Human Hippocampus

Science.gov (United States)

Zhang, Honghui

2015-01-01

The hippocampal theta oscillation is strongly correlated with behaviors such as memory and spatial navigation, but we do not understand its specific functional role. One hint of theta's function came from the discovery in rodents that theta oscillations are traveling waves that allow parts of the hippocampus to simultaneously exhibit separate oscillatory phases. Because hippocampal theta oscillations in humans have different properties compared with rodents, we examined these signals directly using multielectrode recordings from neurosurgical patients. Our findings confirm that human hippocampal theta oscillations are traveling waves, but also show that these oscillations appear at a broader range of frequencies compared with rodents. Human traveling waves showed a distinctive pattern of spatial propagation such that there is a consistent phase spread across the hippocampus regardless of the oscillations' frequency. This suggests that traveling theta oscillations are important functionally in humans because they coordinate phase coding throughout the hippocampus in a consistent manner. SIGNIFICANCE STATEMENT We show for the first time in humans that hippocampal theta oscillations are traveling waves, moving along the length of the hippocampus in a posterior–anterior direction. The existence of these traveling theta waves is important for understanding hippocampal neural coding because they cause neurons at separate positions in the hippocampus to experience different theta phases simultaneously. The theta phase that a neuron measures is a key factor in how that cell represents behavioral information. Therefore, the existence of traveling theta waves indicates that, to fully understand how a hippocampal neuron represents information, it is vital to also account for that cell's location in addition to conventional measures of neural activity. PMID:26354915

The electric dipole moment of the deuteron from the QCD {theta}-term

Energy Technology Data Exchange (ETDEWEB)

Bsaisou, J.; Liebig, S. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Center for Hadron Physics, Juelich (Germany); Hanhart, C.; Nogga, A.; Wirzba, A. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich (Germany); Forschungszentrum Juelich, JARA - Forces And Matter Experiments, Juelich (Germany); Meissner, U.G. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich (Germany); Forschungszentrum Juelich, JARA - Forces And Matter Experiments, Juelich (Germany); Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Universitaet Bonn, Bethe Center for Theoretical Physics, Bonn (Germany)

2013-03-15

The two-nucleon contributions to the electric dipole moment (EDM) of the deuteron, induced by the QCD {theta}-term, are calculated in the framework of effective field theory up-to-and-including next-to-next-to-leading order. In particular we find for the difference of the deuteron EDM and the sum of proton and neutron EDM induced by the QCD {theta}-term a value of (- 5.4 {+-}3.9) anti {theta} x 10{sup -} {sup 4} e fm. The by far dominant uncertainty comes from the CP- and isospin-violating {pi}NN coupling constant. (orig.)

Independent causal contributions of alpha- and beta-band oscillations during movement selection

NARCIS (Netherlands)

Brinkman, L.; Stolk, A.; Marshall, T.R.; Esterer, S.; Sharp, P.; Dijkerman, H.C.; Lange, F.P. de; Toni, I.

2016-01-01

To select a movement, specific neuronal populations controlling particular features of that movement need to be activated, whereas other populations are downregulated. The selective (dis)inhibition of cortical sensorimotor populations is governed by rhythmic neural activity in the alpha (8-12 Hz)

Asymmetry of the cross section for the reaction. gamma. d. -->. pn induced by linearly polarized. gamma. rays in the energy region E/sub. gamma. / = 0. 4--0. 8 GeV and theta/sup c. m. //sub p/ = 45/sup 0/--95/sup 0/

Energy Technology Data Exchange (ETDEWEB)

Adamyan, F.V.; Akopyan, G.G.; Vartapetyan, G.A.; Galumyan, P.I.; Grabskii, V.O.; Karapetyan, V.V.; Karapetyan, G.V.

1984-03-10

The asymmetry (..sigma..) of the cross section for the reaction ..gamma..d..-->..pn has been measured for the energy range E/sub ..gamma../ = 0.4--0.8 GeV and for the angular interval theta/sup c.m.//sub p/ = 45/sup 0/--95/sup 0/. The results are at odds with the calculations by Ogawa et al. and by Huneke, both based on phenomenological models, and also with the predictions of the partial-wave analysis by Ideda et al., which incorporates dibaryon resonances.

Human exposure to a 60 Hz, 1800 micro tesla magnetic field: a neuro behavioral study; Exposition humaine a un champ magnetique de 1 800 microtesla a 60 Hz: une etude neurocomportementale

Energy Technology Data Exchange (ETDEWEB)

Legros, A.; Corbacio, M.; Prato, F.S.; Thomas, A.W. [Lawson Health Research Institute and University of Western Ontario, St Joseph Health' s Care (Canada); Beuter, A. [Laboratoire IMS Institut de Polytechnique de Bordeaux, Universite de Bordeaux, 33 (France); Goulet, D. [Hydro-Quebec TransEnergie, Montreal (Canada); Lambrozo, J.; Souques, M. [Electricite de France, Service des Etudes Medicales, 75 - Paris (France); Plante, M. [Hydro-Quebec, Direction Sante et securite, Montreal (Canada)

2010-05-15

The effects of time-varying magnetic fields (MF) on humans have been actively investigated for the past three decades. One important unanswered question that scientists continue to investigate is the potential for MF exposure to have acute effects on human biology. Different strategies have been used to tackle this question using various physiological, neuro-physiological and behavioral indicators. For example, researchers investigating electro-encephalography (EEG) have reported that Extremely Low Frequency (ELF, < 300 Hz) MF can increase the resting occipital alpha rhythm (8-12 Hz) [1, 2]. Interestingly, other studies have demonstrated that human motor behavior can be modulated by ELF MF exposure, reporting that such an exposure can reduce anteroposterior standing balance oscillations [3, 4] or decrease physiological tremor intensity [5]. However, the main limitation in this domain is the difficulty of reproducing the results. A possible reason for this is the large variety of experimental approaches employed. Therefore, the aim of this project is to investigate the effects of a 60 Hz, 1800 muT MF exposure on physiological (i.e. heart rate and peripheral blood perfusion), neuro-physiological (brain electrical activity), and behavioral (postural oscillations, voluntary motor functions, and physiological tremor) aspects in humans using a single experimental procedure.Though the results from this study suggest a subtle reduction of human standing balance as well as a subtle increase of physiological tremor amplitude with MF exposure, no effect appeared on other investigated parameters, suggesting that one hour of 60 Hz, 1800 muT MF exposure may modulate human involuntary motor control without being detected in the electrical activity of the brain. (authors)

Kainate-induced network activity in the anterior cingulate cortex.

Science.gov (United States)

Shinozaki, R; Hojo, Y; Mukai, H; Hashizume, M; Murakoshi, T

2016-06-14

Anterior cingulate cortex (ACC) plays a pivotal role in higher order processing of cognition, attention and emotion. The network oscillation is considered an essential means for integration of these CNS functions. The oscillation power and coherence among related areas are often dis-regulated in several psychiatric and pathological conditions with a hemispheric asymmetric manner. Here we describe the network-based activity of field potentials recorded from the superficial layer of the mouse ACC in vitro using submerged type recordings. A short activation by kainic acid administration to the preparation induced populational activities ranging over several frequency bands including theta (3-8Hz), alpha (8-12Hz), beta (13-30Hz), low gamma (30-50Hz) and high gamma (50-80Hz). These responses were repeatable and totally abolished by tetrodotoxin, and greatly diminished by inhibitors of ionotropic and metabotropic glutamate receptors, GABAA receptor or gap-junctions. These observations suggest that the kainate-induced network activity can be a useful model of the network oscillation in the ACC circuit. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Increase of EEG spectral theta power indicates higher risk of the development of severe cognitive decline in Parkinson’s disease after 3 years

Directory of Open Access Journals (Sweden)

Vitalii V Cozac

2016-11-01

Full Text Available Objective: We investigated quantitative electroencephalography (qEEG and clinical parameters as potential risk factors of severe cognitive decline in Parkinson’s disease.Methods: We prospectively investigated 37 patients with Parkinson’s disease at baseline and follow-up (after 3 years. Patients had no severe cognitive impairment at baseline. We used a summary score of cognitive tests as the outcome at follow-up. At baseline we assessed motor, cognitive, and psychiatric factors; qEEG variables (global relative median power spectra were obtained by a fully automated processing of high-resolution EEG (256-channels. We used linear regression models with calculation of the explained variance to evaluate the relation of baseline parameters with cognitive deterioration.Results: The following baseline parameters significantly predicted severe cognitive decline: global relative median power theta (4-8 Hz, cognitive task performance in executive functions and working memory.Conclusions: Combination of neurocognitive tests and qEEG improves identification of patients with higher risk of cognitive decline in PD.

Tumour necrosis factor-alpha (TNF-alpha) transcription and translation in the CD4+ T cell-transplanted scid mouse model of colitis

DEFF Research Database (Denmark)

Williams, A M; Whiting, C V; Bonhagen, K

1999-01-01

The adoptive transfer of activated CD4+ alpha/beta T cell blasts from the spleens of immunocompetent C.B-17+/+ or BALB/cdm2 mice into C.B-17scid/scid (scid) mice induces a colitis in the scid recipient within 8 weeks, which progresses to severe disease within 16 weeks. T cells isolated from......-labelled riboprobes were used. The prominent myeloid cell infiltrate in diseased tissues comprised F4/80+, Mac-l+ macrophages, neutrophils, dendritic cells and activated macrophages. TNF-alpha transcription and translation were associated with activated macrophages in the lamina propria. Activated macrophages...

[Microsleep from the electro- and psychophysiological point of view].

Science.gov (United States)

Faber, J; Novák, M; Svoboda, P; Tatarinov, V; Tichý, T

2003-01-01

Impaired wakefulness in machine operators poses a danger not only to themselves but often also to the public at large. While on duty, such persons are expected to be continuously, i.e., without interruption, on the alert. For that purpose, we designed and carried out an experimental model of continuous vigilance monitoring using electroencephalography (EEG) and reaction time measured as the latency of the proband's reaction to sound. If constructed, the set together with other logical elements and an alarm can make for an automatic detection of vigilance and, possibly, also of arousal stimuli in cases of microsleep. We found the following new facts and confirmed the validity of some of the earlier ones: Vigilance is marked by alpha activity in the EEG record (oscillation of 8-13 Hz) and reaction time (RT) of 200-400 ms (milliseconds). Sleep is characterized by theta and delta activities (4-7 and 0.5-3.5 Hz respectively) with no reaction. Between wakefulness and sleep there are at least two stages: relaxation with prolonged RT of 400 to 800 ms and increased EEG alpha, sometimes also beta activities. Then there is the hypnagogic phase with disintegrating alpha and growing theta or even delta activities and an RT of 800 up to 1200 ms. Changes in the EEG and its spectrum and their actual localization on the cranial surface exhibit individual differences; hence, no straightforward categories for the above stages can be established. As for changes in vigilance in the relaxation and hypnagogic phases as well as in the processes of mentation, the most significant are the alpha and delta, less so the theta and beta bands. The most suitable sites for the detection of those changes on the skull surface are temporo-parieto-occipital (TPO) regions, i.e., those over the posterior parts of the skull with the least muscle and oculomotor artifacts and with the most energy for alpha and delta activities. In somnolence, the cortex does not behave as a whole, which means that

Three-dimensional ideal theta(1)/theta(2) angular transformer and its uses in fiber optics.

Science.gov (United States)

Ning, X

1988-10-01

A 3-D ideal theta(1)/theta(2) angular transformer in nonimaging optics is introduced. The axially symmetric transformer, combining a portion of a hyperbolic concentrator with two lenses, transforms an input limited Lambertian over an angle theta(1) to an output limited Lambertian over an angle theta(2) without losing throughput. This is the first known transformer with such ideal properties. Results of computer simulations of a transformer with planospherical lenses are presented. Because of its ideal angular transforming property, the transformer offers an excellent solution for power launching and fiber-fiber coupling in optical fiber systems. In principle, the theoretical maximum coupling efficiency based on radiance conservation can be achieved with this transformer. Several conceptual designs of source-fiber and fiber-fiber couplers using the transformer are given.

Brain dynamics that correlate with effects of learning on auditory distance perception

Directory of Open Access Journals (Sweden)

Matthew G. Wisniewski

2014-12-01

Full Text Available Accuracy in auditory distance perception can improve with practice and varies for sounds differing in familiarity. Here, listeners were trained to judge the distances of English, Bengali, and backwards speech sources pre-recorded at near (2-m and far (30-m distances. Listeners’ accuracy was tested before and after training. Improvements from pre-test to post-test were greater for forward speech, demonstrating a learning advantage for forward speech sounds. Independent component (IC processes identified in electroencephalographic (EEG data collected during pre- and post-testing revealed three clusters of ICs across subjects with stimulus-locked spectral perturbations related to learning and accuracy. One cluster exhibited a transient stimulus-locked increase in 4-8 Hz power (theta event-related synchronization; ERS that was smaller after training and largest for backwards speech. For a left temporal cluster, 8-12 Hz decreases in power (alpha event-related desynchronization; ERD were greatest for English speech and less prominent after training. In contrast, a cluster of IC processes centered at or near anterior portions of the medial frontal cortex showed learning-related enhancement of sustained increases in 10-16 Hz power (upper-alpha/low-beta ERS. The degree of this enhancement was positively correlated with the degree of behavioral improvements. Results suggest that neural dynamics in non-auditory cortical areas support distance judgments. Further, frontal cortical networks associated with attentional and/or working memory processes appear to play a role in perceptual learning for source distance.

Characterizing synchrony patterns across cognitive task stages of associative recognition memory.

Science.gov (United States)

Portoles, Oscar; Borst, Jelmer P; van Vugt, Marieke K

2017-12-28

Numerous studies seek to understand the role of oscillatory synchronization in cognition. This problem is particularly challenging in the context of complex cognitive behavior, which consists of a sequence of processing steps with uncertain duration. In this study, we analyzed oscillatory connectivity measures in time windows that previous computational models had associated with a specific sequence of processing steps in an associative memory recognition task (visual encoding, familiarity, memory retrieval, decision making, and motor response). The timing of these processing steps was estimated on a single-trial basis with a novel hidden semi-Markov model multivariate pattern analysis (HSMM-MVPA) method. We show that different processing stages are associated with specific patterns of oscillatory connectivity. Visual encoding is characterized by a dense network connecting frontal, posterior, and temporal areas as well as frontal and occipital phase locking in the 4-9 Hz theta band. Familiarity is associated with frontal phase locking in the 9-14 Hz alpha band. Decision making is associated with frontal and temporo-central interhemispheric connections in the alpha band. During decision making, a second network in the theta band that connects left-temporal, central, and occipital areas bears similarity to the neural signature for preparing a motor response. A similar theta band network is also present during the motor response, with additionally alpha band connectivity between right-temporal and posterior areas. This demonstrates that the processing stages discovered with the HSMM-MVPA method are indeed linked to distinct synchronization patterns, leading to a closer understanding of the functional role of oscillations in cognition. © 2017 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Measurement of the occipital alpha rhythm and temporal tau rhythm by using magnetoencephalography

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Kim, J. E.; Gohel, Bakul; Kim, K.; Kwon, H.; An, Kyung Min [Center for Biosignals, Korea Research Institute of Standards and Science(KRISS), Daejeon (Korea, Republic of)

2015-12-15

Developing Magnetoencephalography (MEG) based on Superconducting Quantum Interference Device (SQUID) facilitates to observe the human brain functions in non-invasively and high temporal and high spatial resolution. By using this MEG, we studied alpha rhythm (8-13 Hz) that is one of the most predominant spontaneous rhythm in human brain. The 8–13 Hz rhythm is observed in several sensory region in the brain. In visual related region of occipital, we call to alpha rhythm, and auditory related region of temporal call to tau rhythm, sensorimotor related region of parietal call to mu rhythm. These rhythms are decreased in task related region and increased in task irrelevant regions. This means that these rhythms play a pivotal role of inhibition in task irrelevant region. It may be helpful to attention to the task. In several literature about the alpha-band inhibition in multi-sensory modality experiment, they observed this effect in the occipital and somatosensory region. In this study, we hypothesized that we can also observe the alpha-band inhibition in the auditory cortex, mediated by the tau rhythm. Before that, we first investigated the existence of the alpha and tau rhythm in occipital and temporal region, respectively. To see these rhythms, we applied the visual and auditory stimulation, in turns, suppressed in task relevant regions, respectively.

Measurement of the occipital alpha rhythm and temporal tau rhythm by using magnetoencephalography

International Nuclear Information System (INIS)

Kim, J. E.; Gohel, Bakul; Kim, K.; Kwon, H.; An, Kyung Min

2015-01-01

Developing Magnetoencephalography (MEG) based on Superconducting Quantum Interference Device (SQUID) facilitates to observe the human brain functions in non-invasively and high temporal and high spatial resolution. By using this MEG, we studied alpha rhythm (8-13 Hz) that is one of the most predominant spontaneous rhythm in human brain. The 8–13 Hz rhythm is observed in several sensory region in the brain. In visual related region of occipital, we call to alpha rhythm, and auditory related region of temporal call to tau rhythm, sensorimotor related region of parietal call to mu rhythm. These rhythms are decreased in task related region and increased in task irrelevant regions. This means that these rhythms play a pivotal role of inhibition in task irrelevant region. It may be helpful to attention to the task. In several literature about the alpha-band inhibition in multi-sensory modality experiment, they observed this effect in the occipital and somatosensory region. In this study, we hypothesized that we can also observe the alpha-band inhibition in the auditory cortex, mediated by the tau rhythm. Before that, we first investigated the existence of the alpha and tau rhythm in occipital and temporal region, respectively. To see these rhythms, we applied the visual and auditory stimulation, in turns, suppressed in task relevant regions, respectively

Gamma power is phase-locked to posterior alpha activity.

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Daria Osipova

Full Text Available Neuronal oscillations in various frequency bands have been reported in numerous studies in both humans and animals. While it is obvious that these oscillations play an important role in cognitive processing, it remains unclear how oscillations in various frequency bands interact. In this study we have investigated phase to power locking in MEG activity of healthy human subjects at rest with their eyes closed. To examine cross-frequency coupling, we have computed coherence between the time course of the power in a given frequency band and the signal itself within every channel. The time-course of the power was calculated using a sliding tapered time window followed by a Fourier transform. Our findings show that high-frequency gamma power (30-70 Hz is phase-locked to alpha oscillations (8-13 Hz in the ongoing MEG signals. The topography of the coupling was similar to the topography of the alpha power and was strongest over occipital areas. Interestingly, gamma activity per se was not evident in the power spectra and only became detectable when studied in relation to the alpha phase. Intracranial data from an epileptic subject confirmed these findings albeit there was slowing in both the alpha and gamma band. A tentative explanation for this phenomenon is that the visual system is inhibited during most of the alpha cycle whereas a burst of gamma activity at a specific alpha phase (e.g. at troughs reflects a window of excitability.

A cognitive brain-computer interface for patients with amyotrophic lateral sclerosis.

Science.gov (United States)

Hohmann, M R; Fomina, T; Jayaram, V; Widmann, N; Förster, C; Just, J; Synofzik, M; Schölkopf, B; Schöls, L; Grosse-Wentrup, M

2016-01-01

Brain-computer interfaces (BCIs) are often based on the control of sensorimotor processes, yet sensorimotor processes are impaired in patients suffering from amyotrophic lateral sclerosis (ALS). We devised a new paradigm that targets higher-level cognitive processes to transmit information from the user to the BCI. We instructed five ALS patients and twelve healthy subjects to either activate self-referential memories or to focus on a process without mnemonic content while recording a high-density electroencephalogram (EEG). Both tasks are designed to modulate activity in the default mode network (DMN) without involving sensorimotor pathways. We find that the two tasks can be distinguished after only one experimental session from the average of the combined bandpower modulations in the theta- (4-7Hz) and alpha-range (8-13Hz), with an average accuracy of 62.5% and 60.8% for healthy subjects and ALS patients, respectively. The spatial weights of the decoding algorithm show a preference for the parietal area, consistent with modulation of neural activity in primary nodes of the DMN. © 2016 Elsevier B.V. All rights reserved.

Low and then high frequency oscillations of distinct right cortical networks are progressively enhanced by medium and long term Satyananda Yoga meditation practice

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John eThomas

2014-06-01

Full Text Available Meditation proficiency is related to trait-like (learned effects on brain function, developed over time. Previous studies show increases in EEG power in lower frequency bands (theta, alpha in experienced meditators in both meditation states and baseline conditions. Higher gamma band power has been found in advanced Buddhist meditators, yet it is not known if this occurs in Yoga meditation practices. This study used eLORETA to compare differences in cortical source activity underlying scalp EEG from intermediate (mean experience 4 years and advanced (mean experience 30 years Australian meditators from the Satyananda Yoga tradition during a body-steadiness meditation, mantra meditation and non-meditation mental calculation condition. Intermediate Yoga meditators showed greater source activity in low frequencies (particularly theta and alpha1 during mental calculation, body-steadiness and mantra meditation. A similar spatial pattern of significant differences was found in all conditions but the number of significant voxels was double during body-steadiness and mantra meditation than in the non-meditation (calculation condition. These differences were greatest in right (R superior frontal and R precentral gyri and extended back to include the R parietal and occipital lobes. Advanced Yoga meditators showed greater activity in high frequencies (beta and especially gamma in all conditions but greatly expanded during meditation practice. Across all conditions (meditation and non-meditation differences were greatest in the same regions; R insula, R inferior frontal gyrus and R anterior temporal lobe. Distinct R core networks were identified in alpha1 (8-10 Hz and gamma (25-42 Hz bands respectively. The voxels recruited to these networks greatly expanded during meditation practice to include homologous regions of the left hemisphere. Functional interpretation parallels traditionally described stages of development in Yoga proficiency.

Theta-Generalized closed sets in fuzzy topological spaces

International Nuclear Information System (INIS)

El-Shafei, M.E.; Zakari, A.

2006-01-01

In this paper we introduce the concepts of theta-generalized closed fuzzy sets and generalized fuzzy sets in topological spaces. Furthermore, generalized fuzzy sets are extended to theta-generalized fuzzy sets. Also, we introduce the concepts of fuzzy theta-generalized continuous and fuzzy theta-generalized irresolute mappings. (author)

Common and differential electrophysiological mechanisms underlying semantic object memory retrieval probed by features presented in different stimulus types.

Science.gov (United States)

Chiang, Hsueh-Sheng; Eroh, Justin; Spence, Jeffrey S; Motes, Michael A; Maguire, Mandy J; Krawczyk, Daniel C; Brier, Matthew R; Hart, John; Kraut, Michael A

2016-08-01

How the brain combines the neural representations of features that comprise an object in order to activate a coherent object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). We examined this question using three versions of a modified Semantic Object Retrieval Test, where object memory was probed by a feature presented as a written word, a spoken word, or a picture, followed by a second feature always presented as a visual word. Participants indicated whether each feature pair elicited retrieval of the memory of a particular object. Sixteen subjects completed one of the three versions (N=48 in total) while their EEG were recorded simultaneously. We analyzed EEG data in four separate frequency bands (delta: 1-4Hz, theta: 4-7Hz; alpha: 8-12Hz; beta: 13-19Hz) using a multivariate data-driven approach. We found that alpha power time-locked to response was modulated by both cross-modality (visual vs. auditory) and cross-domain (verbal vs. nonverbal) probing of semantic object memory. In addition, retrieval trials showed greater changes in all frequency bands compared to non-retrieval trials across all stimulus types in both response-locked and stimulus-locked analyses, suggesting dissociable neural subcomponents involved in binding object features to retrieve a memory. We conclude that these findings support both modality/domain-dependent and modality/domain-independent mechanisms during semantic object memory retrieval. Copyright © 2016 Elsevier B.V. All rights reserved.

Wind Turbine Power Generation Emulation Via Doubly Fed Induction Generator Control

Science.gov (United States)

2009-12-01

vde thetas vqs_pu vds_pu synchronous...to stationary 0 ide_ref 200 Vdc_ref I_ref I_meas vqe PI iq I_ref I_meas vde PI id v_ref v_meas iqs PI Vdc 4 theta_s 3 ide 2 iqe 1 Vdc 21 between...1-1 x(-1)- a b a + b+ Sy stem Generator Variac P/S 60V 60HzVariac P/S 60V 60Hz 70 Vabc_s THETA CALCULATION 5 vde 4 vqe 3 Vas 2 Vdc_out 1

Mapping of HNF4alpha target genes in intestinal epithelial cells

DEFF Research Database (Denmark)

Boyd, Mette; Bressendorff, Simon; Moller, Jette

2009-01-01

ABSTRACT: BACKGROUND: The role of HNF4alpha has been extensively studied in hepatocytes and pancreatic beta-cells, and HNF4alpha is also regarded as key regulator of intestinal epithelial cell differentiation as well. The aim of the present work is to identify novel HNF4alpha target genes....... The HNF4alpha ChIP-chip data was matched with gene expression and histone H3 acetylation status of the promoters in order to identify HNF4alpha binding to actively transcribed genes with an open chromatin structure. RESULTS: 1,541 genes were identified as potential HNF4alpha targets, many of which have...

Production of $\\Theta^{+}$ (1540) and $\\Xi$ pentaquark states in proton- proton interactions

CERN Document Server

Bleicher, M; Liu, F M; Pierog, T; Werner, K; 10.1016/j.physletb.2004.05.010

2004-01-01

The production of strange pentaquark states (e.g., Theta baryons and Xi /sup --/states) in hadronic interactions within a Gribov-Regge approach is explored. In this approach the Theta /sup +/(1540) and the Xi are produced by disintegration of remnants formed by the exchange of pomerons between the two protons. We predict the rapidity and transverse momentum distributions as well as the 4 pi multiplicity of the Theta /sup +/, Xi /sup --/ , Xi /sup -/, Xi /sup 0/ and Xi /sup +/ for square root s=17 GeV (SPS) and 200 GeV (RHIC). For both energies more than 10/sup -3/ Theta /sup +/ and more than 10 /sup -5/ Xi per pp event should be observed by the present experiments.

Electric giant resonances in sup 4 sup 0 Ca and sup 4 sup 8 Ca probed with electron and proton scattering coincidence experiments

CERN Document Server

Strauch, S

1999-01-01

Excitation and particle decay of electric giant resonances in sup 4 sup 0 Ca and sup 4 sup 8 Ca are studied with electron and proton beams. Recent results of a sup 4 sup 8 Ca(e,e'n) measurement performed at the S-DALINAC in Darmstadt with kinematics that selectively populate electric monopole, dipole and quadrupole excitations are presented. The extracted B(E1) strength distribution is in good agreement with photo nuclear data and the predictions of microscopic calculations. The summed B(E2+E0) strength distribution, however disagrees with the result of these calculations. The neutron emission of the giant dipole resonance in sup 4 sup 8 Ca shows a large fraction of direct decay to sup 4 sup 7 Ca hole states. In addition, isoscalar giant monopole resonance strength in sup 4 sup 0 Ca was extracted from (e,e'alpha sub 0) and (e,e'alpha sub 1) angular correlations. A study of the quadrupole strength in the alpha sub 0 decay channel of sup 4 sup 0 Ca with a (p,p'alpha) coincidence measurement reiterates the unsol...

Graph properties of synchronized cortical networks during visual working memory maintenance.

Science.gov (United States)

Palva, Satu; Monto, Simo; Palva, J Matias

2010-02-15

Oscillatory synchronization facilitates communication in neuronal networks and is intimately associated with human cognition. Neuronal activity in the human brain can be non-invasively imaged with magneto- (MEG) and electroencephalography (EEG), but the large-scale structure of synchronized cortical networks supporting cognitive processing has remained uncharacterized. We combined simultaneous MEG and EEG (MEEG) recordings with minimum-norm-estimate-based inverse modeling to investigate the structure of oscillatory phase synchronized networks that were active during visual working memory (VWM) maintenance. Inter-areal phase-synchrony was quantified as a function of time and frequency by single-trial phase-difference estimates of cortical patches covering the entire cortical surfaces. The resulting networks were characterized with a number of network metrics that were then compared between delta/theta- (3-6 Hz), alpha- (7-13 Hz), beta- (16-25 Hz), and gamma- (30-80 Hz) frequency bands. We found several salient differences between frequency bands. Alpha- and beta-band networks were more clustered and small-world like but had smaller global efficiency than the networks in the delta/theta and gamma bands. Alpha- and beta-band networks also had truncated-power-law degree distributions and high k-core numbers. The data converge on showing that during the VWM-retention period, human cortical alpha- and beta-band networks have a memory-load dependent, scale-free small-world structure with densely connected core-like structures. These data further show that synchronized dynamic networks underlying a specific cognitive state can exhibit distinct frequency-dependent network structures that could support distinct functional roles. Copyright 2009 Elsevier Inc. All rights reserved.

High-alpha band synchronization across frontal, parietal and visual cortex mediates behavioral and neuronal effects of visuospatial attention.

Science.gov (United States)

Lobier, Muriel; Palva, J Matias; Palva, Satu

2018-01-15

Visuospatial attention prioritizes processing of attended visual stimuli. It is characterized by lateralized alpha-band (8-14 Hz) amplitude suppression in visual cortex and increased neuronal activity in a network of frontal and parietal areas. It has remained unknown what mechanisms coordinate neuronal processing among frontoparietal network and visual cortices and implement the attention-related modulations of alpha-band amplitudes and behavior. We investigated whether large-scale network synchronization could be such a mechanism. We recorded human cortical activity with magnetoencephalography (MEG) during a visuospatial attention task. We then identified the frequencies and anatomical networks of inter-areal phase synchronization from source localized MEG data. We found that visuospatial attention is associated with robust and sustained long-range synchronization of cortical oscillations exclusively in the high-alpha (10-14 Hz) frequency band. This synchronization connected frontal, parietal and visual regions and was observed concurrently with amplitude suppression of low-alpha (6-9 Hz) band oscillations in visual cortex. Furthermore, stronger high-alpha phase synchronization was associated with decreased reaction times to attended stimuli and larger suppression of alpha-band amplitudes. These results thus show that high-alpha band phase synchronization is functionally significant and could coordinate the neuronal communication underlying the implementation of visuospatial attention. Copyright © 2017 Elsevier Inc. All rights reserved.

Estimating direction in brain-behavior interactions: Proactive and reactive brain states in driving.

Science.gov (United States)

Garcia, Javier O; Brooks, Justin; Kerick, Scott; Johnson, Tony; Mullen, Tim R; Vettel, Jean M

2017-04-15

Conventional neuroimaging analyses have ascribed function to particular brain regions, exploiting the power of the subtraction technique in fMRI and event-related potential analyses in EEG. Moving beyond this convention, many researchers have begun exploring network-based neurodynamics and coordination between brain regions as a function of behavioral parameters or environmental statistics; however, most approaches average evoked activity across the experimental session to study task-dependent networks. Here, we examined on-going oscillatory activity as measured with EEG and use a methodology to estimate directionality in brain-behavior interactions. After source reconstruction, activity within specific frequency bands (delta: 2-3Hz; theta: 4-7Hz; alpha: 8-12Hz; beta: 13-25Hz) in a priori regions of interest was linked to continuous behavioral measurements, and we used a predictive filtering scheme to estimate the asymmetry between brain-to-behavior and behavior-to-brain prediction using a variant of Granger causality. We applied this approach to a simulated driving task and examined directed relationships between brain activity and continuous driving performance (steering behavior or vehicle heading error). Our results indicated that two neuro-behavioral states may be explored with this methodology: a Proactive brain state that actively plans the response to the sensory information and is characterized by delta-beta activity, and a Reactive brain state that processes incoming information and reacts to environmental statistics primarily within the alpha band. Published by Elsevier Inc.

Uniform decrease of alpha-global field power induced by intermittent photic stimulation of healthy subjects

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Rau R.

2002-01-01

Full Text Available Nineteen-channel EEGs were recorded from the scalp surface of 30 healthy subjects (16 males and 14 females, mean age: 34 years, SD: 11.7 years at rest and under trains of intermittent photic stimulation (IPS at rates of 5, 10 and 20 Hz. Digitalized data were submitted to spectral analysis with fast fourier transformation providing the basis for the computation of global field power (GFP. For quantification, GFP values in the frequency ranges of 5, 10 and 20 Hz at rest were divided by the corresponding data obtained under IPS. All subjects showed a photic driving effect at each rate of stimulation. GFP data were normally distributed, whereas ratios from photic driving effect data showed no uniform behavior due to high interindividual variability. Suppression of alpha-power after IPS with 10 Hz was observed in about 70% of the volunteers. In contrast, ratios of alpha-power were unequivocal in all subjects: IPS at 20 Hz always led to a suppression of alpha-power. Dividing alpha-GFP with 20-Hz IPS by alpha-GFP at rest (R = alpha-GFP IPS/alpha-GFPrest thus resulted in ratios lower than 1. We conclude that ratios from GFP data with 20-Hz IPS may provide a suitable paradigm for further investigations.

Ketamine increases the frequency of electroencephalographic bicoherence peak on the alpha spindle area induced with propofol.

Science.gov (United States)

Hayashi, K; Tsuda, N; Sawa, T; Hagihira, S

2007-09-01

The reticular and thalamocortical system is known to play a prominent role in spindle wave activity, and the spindle wave is related to the sedative effects of anaesthetics. Recently, bispectral analysis of the EEG has been developed as a better method to indicate nonlinear regulation including the thalamocortical system linking to the cortical area. In the present study, in order to explore the interference of ketamine with the nonlinear regulation of the sub-cortical system, we examined the effect of ketamine on spindle alpha waves through the bispectral analysis. The study included 21 patients. Anaesthesia was induced and maintained using a propofol-TCI system (target-controlled infusion, with target concentration 3.5 microg ml(-1)). An A-2000 BIS monitor was used and the raw EEG signals were collected via an RS232 interface on a personal computer. Bicoherence, the normalized bispectrum, and power spectrum were analysed before and after i.v. administration of 1 mg kg(-1) racemic ketamine. Propofol caused alpha peaks in both power and bicoherence spectra, with average frequencies of 10.6 (SD 0.9) Hz and 10.7 (1.0) Hz, respectively. The addition of ketamine significantly shifted each peak to frequencies of 14.4 (1.4) Hz and 13.6 (1.5) Hz, respectively [P < 0.05, mean (SD)]. Ketamine shifted the alpha peaks of bicoherence induced by propofol to higher frequencies. This suggests that ketamine changes the alpha spindle rhythms through the modulation of the nonlinear sub-cortical reverberating network.

Uniaxial strain effects on transport properties of a supramolecular organic conductor theta-(DIETS) sub 2 [Au(CN) sub 4

CERN Document Server

Tajima, N; Kato, R; Nishio, Y; Kajita, K

2003-01-01

Pressure-controlled switching between an insulating state and a superconducting state has been successfully realized on a supramolecular organic conductor theta-(DIETS) sub 2 [Au(CN) sub 4] [DIETS = diiodo(ethylenedithio)diselenadithiafulvalene]. Strong contact between iodine on the donor (DIETS) molecule and nitrogen on the anion [Au(CN) sub 4] genetates characteristic uniaxial strain effects on transport properties. Under the ambient pressure, the present system undergoes a semiconductor-insulator transition at 226 K. The effect of strains parallel to the conduction plane (ab-plane) is very small. Even under uniaxial strains up to 20 kbar along the a- and b-axis directions, the transition is not suppressed. Surprisingly, however, the c-axis strain induces a superconducting state with T sub c of 8.6 K at 10 kbar. Band parameter calculation and the conductivity anisotropy ratio suggest that an increase in the bandwidth W associated with a c-axis strain transforms the system to the metallic and superconducting...

Predicting tDCS treatment outcomes of patients with major depressive disorder using automated EEG classification.

Science.gov (United States)

Al-Kaysi, Alaa M; Al-Ani, Ahmed; Loo, Colleen K; Powell, Tamara Y; Martin, Donel M; Breakspear, Michael; Boonstra, Tjeerd W

2017-01-15

Transcranial direct current stimulation (tDCS) is a promising treatment for major depressive disorder (MDD). Standard tDCS treatment involves numerous sessions running over a few weeks. However, not all participants respond to this type of treatment. This study aims to investigate the feasibility of identifying MDD patients that respond to tDCS treatment based on resting-state electroencephalography (EEG) recorded prior to treatment commencing. We used machine learning to predict improvement in mood and cognition during tDCS treatment from baseline EEG power spectra. Ten participants with a current diagnosis of MDD were included. Power spectral density was assessed in five frequency bands: delta (0.5-4Hz), theta (4-8Hz), alpha (8-12Hz), beta (13-30Hz) and gamma (30-100Hz). Improvements in mood and cognition were assessed using the Montgomery-Åsberg Depression Rating Scale and Symbol Digit Modalities Test, respectively. We trained the classifiers using three algorithms (support vector machine, extreme learning machine and linear discriminant analysis) and a leave-one-out cross-validation approach. Mood labels were accurately predicted in 8 out of 10 participants using EEG channels FC4-AF8 (accuracy=76%, p=0.034). Cognition labels were accurately predicted in 10 out of 10 participants using channels pair CPz-CP2 (accuracy=92%, p=0.004). Due to the limited number of participants (n=10), the presented results mainly aim to serve as a proof of concept. These finding demonstrate the feasibility of using machine learning to identify patients that will respond to tDCS treatment. These promising results warrant a larger study to determine the clinical utility of this approach. Copyright © 2016 Elsevier B.V. All rights reserved.

Other characterizations of $\\beta$-$\\theta$-R0 topological spaces

OpenAIRE

Miguel Caldas Cueva

2013-01-01

In this paper we give other characterizations of $\\beta$-$\\theta$-$%R_0$ and also introduce a new separation axiom called$\\beta$-$\\theta$-$R_1$. It turns out that $\\beta$-$\\theta$-$R_1$ isstronger that $\\beta$-$\\theta$-$R_0$

A 7.8 kV nanosecond pulse generator with a 500 Hz repetition rate

Science.gov (United States)

Lin, M.; Liao, H.; Liu, M.; Zhu, G.; Yang, Z.; Shi, P.; Lu, Q.; Sun, X.

2018-04-01

Pseudospark switches are widely used in pulsed power applications. In this paper, we present the design and performance of a 500 Hz repetition rate high-voltage pulse generator to drive TDI-series pseudospark switches. A high-voltage pulse is produced by discharging an 8 μF capacitor through a primary windings of a setup isolation transformer using a single metal-oxide-semiconductor field-effect transistor (MOSFET) as a control switch. In addition, a self-break spark gap is used to steepen the pulse front. The pulse generator can deliver a high-voltage pulse with a peak trigger voltage of 7.8 kV, a peak trigger current of 63 A, a full width at half maximum (FWHM) of ~30 ns, and a rise time of 5 ns to the trigger pin of the pseudospark switch. During burst mode operation, the generator achieved up to a 500 Hz repetition rate. Meanwhile, we also provide an AC heater power circuit for heating a H2 reservoir. This pulse generator can be used in circuits with TDI-series pseudospark switches with either a grounded cathode or with a cathode electrically floating operation. The details of the circuits and their implementation are described in the paper.

Short-term effects of repeated olfactory administration of homeopathic sulphur or pulsatilla on electroencephalographic alpha power in healthy young adults.

Science.gov (United States)

Bell, Iris R; Brooks, Audrey J; Howerter, Amy; Jackson, Nicholas; Schwartz, Gary E

2011-10-01

Homeopathic pathogenetic trials usually rely on symptom self report measures. Adding objective biomarkers could enhance detection of subtle initial remedy effects. The present feasibility study examined electroencephalographic (EEG) effects of repeated olfactory administration of two polycrest remedies. College student volunteers (ages 18-30, both sexes) from an introductory psychology course were screened for good health and relatively elevated Sulphur or Pulsatilla symptom scores on the Homeopathic Constitutional Type Questionnaire (CTQ). Subjects underwent a series of 3 once-weekly double-blind sessions during which they repeatedly sniffed the remedy matched to their CTQ type and solvent controls. Each remedy was given in a 6c, 12c, and 30c potency, one potency per week, in randomly assigned order. Solvent controls included both plain distilled water and a water-ethanol (95%) solution. All sniff test solutions were further diluted just prior to laboratory sessions (0.5 ml test solution in 150 ml distilled water). Within a session, remedies and control solvents were administered via 2-s sniffs (8 sniffs of each of 4 different succussion levels for the potency in randomized order). Primary outcome variable was relative EEG power (alpha 1 8-10 Hz; alpha 2 10-12 Hz) averaged over 19 electrode sites, including all succussions for a given potency. Mixed-effect models revealed significant main effects for remedy type (Sulphur >Pulsatilla) in both alpha bands, controlling for gender, baseline resting EEG alpha, and solvent control responses. Additional analyses showed significant nonlinear interactions between dilution and time (weekly session) in alpha 2 for both remedies and alpha 1 for Sulphur. EEG alpha offers an objective biomarker of remedy effects for future studies and potential method for distinguishing time-dependent effects of specific remedies and remedy potencies from one another. Copyright © 2011 The Faculty of Homeopathy. Published by Elsevier Ltd

MEG-based detection and localization of perilesional dysfunction in chronic stroke

Directory of Open Access Journals (Sweden)

Ron K.O. Chu

2015-01-01

Full Text Available Post-stroke impairment is associated not only with structural lesions, but also with dysfunction in surviving perilesional tissue. Previous studies using equivalent current dipole source localization of MEG/EEG signals have demonstrated a preponderance of slow-wave activity localized to perilesional areas. Recent studies have also demonstrated the utility of nonlinear analyses such as multiscale entropy (MSE for quantifying neuronal dysfunction in a wide range of pathologies. The current study utilized beamformer-based reconstruction of signals in source space to compare spectral and nonlinear measures of electrical activity in perilesional and healthy cortices. Data were collected from chronic stroke patients and healthy controls, both young and elderly. We assessed relative power in the delta (1–4 Hz, theta (4–7 Hz, alpha (8–12 Hz and beta (15–30 Hz frequency bands, and also measured the nonlinear complexity of electrical activity using MSE. Perilesional tissue exhibited a general slowing of the power spectrum (increased delta/theta, decreased beta as well as a reduction in MSE. All measures tested were similarly sensitive to changes in the posterior perilesional regions, but anterior perilesional dysfunction was detected better by MSE and beta power. The findings also suggest that MSE is specifically sensitive to electrophysiological dysfunction in perilesional tissue, while spectral measures were additionally affected by an increase in rolandic beta power with advanced age. Furthermore, perilesional electrophysiological abnormalities in the left hemisphere were correlated with the degree of language task-induced activation in the right hemisphere. Finally, we demonstrate that single subject spectral and nonlinear analyses can identify dysfunctional perilesional regions within individual patients that may be ideal targets for interventions with noninvasive brain stimulation.

Polarized beam asymmetry for. gamma. d. -->. Peta in the energy range 0. 4-0. 8 GeV

Energy Technology Data Exchange (ETDEWEB)

Adamyan, F.V.; Arustamyan, G.V.; Galumyan, P.I.; Grabsky, V.H.; Hakopyan, H.H.; Karapetyan, V.V.; Vartapetyan, H.A.

1983-01-01

Measurements of the polarized beam asymmetry for deuteron photodisintegration ..gamma..d ..-->.. Peta have been carried out in the energy range E/sub ..gamma../ = 0.4-0.8 GeV and at angles theta/sub p//sup cm/ = 45/sup 0/-75/sup 0/. The results obtained are in disagreement with theoretical predictions which take into account the dibaryon resonance contribution. The data qualitative analysis indicates the weakness of isoscalar dibaryon amplitudes near E/sub ..gamma../ = 400 MeV. 8 references, 1 figure.

Fasting induces basolateral uptake transporters of the SLC family in the liver via HNF4alpha and PGC1alpha.

Science.gov (United States)

Dietrich, Christoph G; Martin, Ina V; Porn, Anne C; Voigt, Sebastian; Gartung, Carsten; Trautwein, Christian; Geier, Andreas

2007-09-01

Fasting induces numerous adaptive changes in metabolism by several central signaling pathways, the most important represented by the HNF4alpha/PGC-1alpha-pathway. Because HNF4alpha has been identified as central regulator of basolateral bile acid transporters and a previous study reports increased basolateral bile acid uptake into the liver during fasting, we hypothesized that HNF4alpha is involved in fasting-induced bile acid uptake via upregulation of basolateral bile acid transporters. In rats, mRNA of Ntcp, Oatp1, and Oatp2 were significantly increased after 48 h of fasting. Protein expression as determined by Western blot showed significant increases for all three transporters 72 h after the onset of fasting. Whereas binding activity of HNF1alpha in electrophoretic mobility shift assays remained unchanged, HNF4alpha binding activity to the Ntcp promoter was increased significantly. In line with this result, we found significantly increased mRNA expression of HNF4alpha and PGC-1alpha. Functional studies in HepG2 cells revealed an increased endogenous NTCP mRNA expression upon cotransfection with either HNF4alpha, PGC-1alpha, or a combination of both. We conclude that upregulation of the basolateral bile acid transporters Ntcp, Oatp1, and Oatp2 in fasted rats is mediated via the HNF4alpha/PGC-1alpha pathway.

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.

Science.gov (United States)

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.

The importance of ignoring: Alpha oscillations protect selectivity

OpenAIRE

Payne, Lisa; Sekuler, Robert

2014-01-01

Selective attention is often thought to entail an enhancement of some task-relevant stimulus or attribute. We discuss the perspective that ignoring irrelevant, distracting information plays a complementary role in information processing. Cortical oscillations within the alpha (8–14 Hz) frequency band have emerged as a marker of sensory suppression. This suppression is linked to selective attention for visual, auditory, somatic, and verbal stimuli. Inhibiting processing of irrelevant input mak...

Human exposure to a 60 Hz, 1800 micro tesla magnetic field: a neuro behavioral study

International Nuclear Information System (INIS)

Legros, A.; Corbacio, M.; Prato, F.S.; Thomas, A.W.; Beuter, A.; Goulet, D.; Lambrozo, J.; Souques, M.; Plante, M.

2010-01-01

The effects of time-varying magnetic fields (MF) on humans have been actively investigated for the past three decades. One important unanswered question that scientists continue to investigate is the potential for MF exposure to have acute effects on human biology. Different strategies have been used to tackle this question using various physiological, neuro-physiological and behavioral indicators. For example, researchers investigating electro-encephalography (EEG) have reported that Extremely Low Frequency (ELF, < 300 Hz) MF can increase the resting occipital alpha rhythm (8-12 Hz) [1, 2]. Interestingly, other studies have demonstrated that human motor behavior can be modulated by ELF MF exposure, reporting that such an exposure can reduce anteroposterior standing balance oscillations [3, 4] or decrease physiological tremor intensity [5]. However, the main limitation in this domain is the difficulty of reproducing the results. A possible reason for this is the large variety of experimental approaches employed. Therefore, the aim of this project is to investigate the effects of a 60 Hz, 1800 μT MF exposure on physiological (i.e. heart rate and peripheral blood perfusion), neuro-physiological (brain electrical activity), and behavioral (postural oscillations, voluntary motor functions, and physiological tremor) aspects in humans using a single experimental procedure.Though the results from this study suggest a subtle reduction of human standing balance as well as a subtle increase of physiological tremor amplitude with MF exposure, no effect appeared on other investigated parameters, suggesting that one hour of 60 Hz, 1800 μT MF exposure may modulate human involuntary motor control without being detected in the electrical activity of the brain. (authors)

Power of theta waves in the EEG of human subjects increases during recall of haptic information.

Science.gov (United States)

Grunwald, M; Weiss, T; Krause, W; Beyer, L; Rost, R; Gutberlet, I; Gertz, H J

1999-02-05

Several studies have reported a functional relationship between spectral power within the theta-band of the EEG (theta-power) and memory load while processing visual or semantic information. We investigated theta power during the processing of different complex haptic stimuli using a delayed recall design. The haptic explorations consisted of palpating the structure of twelve sunken reliefs with closed eyes. Subjects had to reproduce each relief by drawing it 10 s after the end of the exploration. The relationship between mean theta power and mean exploration time was analysed using a regression model. A linear relationship was found between the exploration time and theta power over fronto-central regions (Fp1, Fp2, F3, F7, F8, Fz, C3) directly before the recall of the relief. This result is interpreted in favour of the hypothesis that fronto-central theta power of the EEG correlates with the load of working memory independent of stimulus modality.

Modulation of EEG Theta Band Signal Complexity by Music Therapy

Science.gov (United States)

Bhattacharya, Joydeep; Lee, Eun-Jeong

The primary goal of this study was to investigate the impact of monochord (MC) sounds, a type of archaic sounds used in music therapy, on the neural complexity of EEG signals obtained from patients undergoing chemotherapy. The secondary goal was to compare the EEG signal complexity values for monochords with those for progressive muscle relaxation (PMR), an alternative therapy for relaxation. Forty cancer patients were randomly allocated to one of the two relaxation groups, MC and PMR, over a period of six months; continuous EEG signals were recorded during the first and last sessions. EEG signals were analyzed by applying signal mode complexity, a measure of complexity of neuronal oscillations. Across sessions, both groups showed a modulation of complexity of beta-2 band (20-29Hz) at midfrontal regions, but only MC group showed a modulation of complexity of theta band (3.5-7.5Hz) at posterior regions. Therefore, the neuronal complexity patterns showed different changes in EEG frequency band specific complexity resulting in two different types of interventions. Moreover, the different neural responses to listening to monochords and PMR were observed after regular relaxation interventions over a short time span.

Better than sleep: theta neurofeedback training accelerates memory consolidation.

Science.gov (United States)

Reiner, Miriam; Rozengurt, Roman; Barnea, Anat

2014-01-01

Consistent empirical results showed that both night and day sleep enhanced memory consolidation. In this study we explore processes of consolidation of memory during awake hours. Since theta oscillations have been shown to play a central role in exchange of information, we hypothesized that elevated theta during awake hours will enhance memory consolidation. We used a neurofeedback protocol, to enhance the relative power of theta or beta oscillations. Participants trained on a tapping task, were divided into three groups: neurofeedback theta; neurofeedback beta; control. We found a significant improvement in performance in the theta group, relative to the beta and control groups, immediately after neurofeedback. Performance was further improved after night sleep in all groups, with a significant advantage favoring the theta group. Theta power during training was correlated with the level of improvement, indicating a clear relationship between memory consolidation, and theta neurofeedback. Copyright © 2013 Elsevier B.V. All rights reserved.

Scattering of alpha particles from /sup 12/C and the /sup 12/C(. cap alpha. ,. gamma. )/sup 16/O stellar reaction rate

Energy Technology Data Exchange (ETDEWEB)

Plaga, R.; Becker, H.W.; Redder, A.; Rolfs, C.; Trautvetter, H.P.; Langanke, K.

1987-04-06

The elastic scattering of alpha particles from /sup 12/C has been investigated for 35 angles in the range theta/sub lab/ = 22/sup 0/ to 163/sup 0/ and for 51 energies at E/sub ..cap alpha../ = 1.0 to 6.6 MeV. The extracted phase shifts for l=0 to 6 partial waves have been parametrized in terms of the multilevel R-matrix formalism. Information on the deduced parameters of states in /sup 16/O is reported. The data reveal reduced ..cap alpha..-particle widths for the 6.92 and 7.12 MeV subthreshold states consistent with recent work. The implications for the stellar reaction rate of /sup 12/C(..cap alpha..,..gamma..)/sup 16/O are discussed.

Theta Burst Stimulation of the Cerebellum Modifies the TMS-Evoked N100 Potential, a Marker of GABA Inhibition.

Directory of Open Access Journals (Sweden)

Allanah Harrington

Full Text Available Theta burst stimulation (TBS of the cerebellum, a potential therapy for neurological disease, can modulate corticospinal excitability via the dentato-thalamo-cortical pathway, but it is uncertain whether its effects are mediated via inhibitory or facilitatory networks. The aim of this study was to investigate the effects of 30Hz cerebellar TBS on the N100 waveform of the TMS-evoked potential (TEP, a marker of intracortical GABAB-mediated inhibition. 16 healthy participants (aged 18-30 years; 13 right handed and 3 left handed received 30Hz intermittent TBS (iTBS, continuous TBS (cTBS or sham stimulation over the right cerebellum, in three separate sessions. The first 8 participants received TBS at a stimulus intensity of 80% of active motor threshold (AMT, while the remainder received 90% of AMT. Motor evoked potentials (MEP and TEP were recorded before and after each treatment, by stimulating the first dorsal interosseus area of the left motor cortex. Analysis of the 13 right handed participants showed that iTBS at 90% of AMT increased the N100 amplitude compared to sham and cTBS, without significantly altering MEP amplitude. cTBS at 80% of active motor threshold decreased the N100 amplitude and cTBS overall reduced resting MEP amplitude. The study demonstrates effects of 30Hz cerebellar TBS on inhibitory cortical networks that may be useful for treatment of neurological conditions associated with dysfunctional intracortical inhibition.

Reconstruction of spin-tensor of 4. 43 MeV state density matrix of the /sup 12/C nucleus in the /sup 12/C(. cap alpha. ,. cap alpha. sub(1). gamma. sub(4,43))/sup 12/C reaction at Esub(. cap alpha. )=25 MeV

Energy Technology Data Exchange (ETDEWEB)

Gurevich, G.S.; Lebedev, V.M.; Orlova, N.V.; Spasskij, A.V.; Teplov, I.B.; Shakhvorostova, G.V.; Belkina, M.R. (Moskovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Yadernoj Fiziki)

1984-01-01

The results of measuring double differential cross sections of the reaction of inelastic scattering 24.8 MeV ..cap alpha..-particles sup(12)C(..cap alpha.., ..cap alpha..sub(1)..gamma..sub(4.43))sup(12)C in different planes of ..gamma..-quantum escape relatively to the plane of the reaction phisub(..gamma..)=30, 60 and 90 deg are presented. Non-monochromaticity of the beam made up 1%. Functions of angular correlation of the reaction are measured for four angles THETAsub(..cap alpha..)=21, 39, 59 and 135 deg corresponding to maxima of differential cross section in angular distribution of inelastically scattered ..cap alpha..-particles and for THETAsub(..cap alpha..)=89 deg corresponding to the minimum of angular distribution. The results of measurements permit to reconstruct all the components of irreducible spin-tensors of the matrix of state density 4.43 MeV (2/sup +/) formed in this reaction. The values of populations of substates by the projection of the spin of this state are obtained. The analysis of the obtained results testify to the fact that mechanism of inelastic scattering is not reduced to impulse approximation and mechanisms associated with delay in interaction do not make noticeable contribution for the given angles of ..cap alpha..-particle escape.

Genetic evidence that HNF-1alpha-dependent transcriptional control of HNF-4alpha is essential for human pancreatic beta cell function

DEFF Research Database (Denmark)

Hansen, Sara K; Párrizas, Marcelina; Jensen, Maria L

2002-01-01

Mutations in the genes encoding hepatocyte nuclear factor 4alpha (HNF-4alpha) and HNF-1alpha impair insulin secretion and cause maturity onset diabetes of the young (MODY). HNF-4alpha is known to be an essential positive regulator of HNF-1alpha. More recent data demonstrates that HNF-4alpha...... in human islets and exocrine cells is primarily mediated by the P2 promoter. Furthermore, we describe a G --> A mutation in a conserved nucleotide position of the HNF-1alpha binding site of the P2 promoter, which cosegregates with MODY. The mutation results in decreased affinity for HNF-1alpha...

Comparison of Sensorimotor Rhythm (SMR) and Beta Training on Selective Attention and Symptoms in Children with Attention Deficit/Hyperactivity Disorder (ADHD): A Trend Report.

Science.gov (United States)

Mohammadi, Mohammad Reza; Malmir, Nastaran; Khaleghi, Ali; Aminiorani, Majd

2015-06-01

The aim of this study was to assess and compare the effect of two neurofeedback protocols (SMR/theta and beta/theta) on ADHD symptoms, selective attention and EEG (electroencephalogram) parameters in children with ADHD. The sample consisted of 16 children (9-15 year old: 13 boys; 3 girls) with ADHD-combined type (ADHD-C). All of children used methylphenidate (MPH) during the study. The neurofeedback training consisted of two phases of 15 sessions, each lasting 45 minutes. In the first phase, participants were trained to enhance sensorimotor rhythm (12-15 Hz) and reduce theta activity (4-8 Hz) at C4 and in the second phase; they had to increase beta (15-18 Hz) and reduce theta activity at C3. Assessments consisted of d2 attention endurance test, ADHD rating scale (parent form) at three time periods: before, middle and the end of the training. EEG signals were recorded just before and after the training. Based on parents' reports, inattention after beta/theta training, and hyperactivity/impulsivity were improved after the end of the training. All subscales of d2 test were improved except for the difference between maximum and minimum responses. However, EEG analysis showed no significant differences. Neurofeedback in conjunction with Methylphenidate may cause further improvement in ADHD symptoms reported by parents and selective attention without long-term impact on EEG patterns. However, determining the exact relationship between EEG parameters, neurofeedback protocols and ADHD symptoms remain unclear.

Sources of series resistance in the Harwell solid state alpha detector

International Nuclear Information System (INIS)

Rawlings, K.J.

1985-12-01

The metal-semiconductor contacts to the Harwell solid state alpha detector have been characterized and the effect of the contact geometry has been assessed. To a reasonable approximation the latter gives rise to an emitter series resistance with an expected range of 20 +- 8 ohms. The contacts behave like parallel RC networks which become noticeably frequency dependent above ca. 100 kHz. Up to this frequency the emitter contact is likely to add 6 +- 4 ohms to the series resistance and the contribution from the base contact varies inversely with the square of the diode's diameter, being 5 +- 3 ohms for a diode with a diameter of 30 mm. (author)

Affective attitudes to face images associated with intracerebral EEG source location before face viewing.

Science.gov (United States)

Pizzagalli, D; Koenig, T; Regard, M; Lehmann, D

1999-01-01

We investigated whether different, personality-related affective attitudes are associated with different brain electric field (EEG) sources before any emotional challenge (stimulus exposure). A 27-channel EEG was recorded in 15 subjects during eyes-closed resting. After recording, subjects rated 32 images of human faces for affective appeal. The subjects in the first (i.e., most negative) and fourth (i.e., most positive) quartile of general affective attitude were further analyzed. The EEG data (mean=25+/-4. 8 s/subject) were subjected to frequency-domain model dipole source analysis (FFT-Dipole-Approximation), resulting in 3-dimensional intracerebral source locations and strengths for the delta-theta, alpha, and beta EEG frequency band, and for the full range (1.5-30 Hz) band. Subjects with negative attitude (compared to those with positive attitude) showed the following source locations: more inferior for all frequency bands, more anterior for the delta-theta band, more posterior and more right for the alpha, beta and 1.5-30 Hz bands. One year later, the subjects were asked to rate the face images again. The rating scores for the same face images were highly correlated for all subjects, and original and retest affective mean attitude was highly correlated across subjects. The present results show that subjects with different affective attitudes to face images had different active, cerebral, neural populations in a task-free condition prior to viewing the images. We conclude that the brain functional state which implements affective attitude towards face images as a personality feature exists without elicitors, as a continuously present, dynamic feature of brain functioning. Copyright 1999 Elsevier Science B.V.

Combinatorics of tenth-order mock theta functions

Indian Academy of Sciences (India)

θ(q) there is some root of unity ζ for which f (q) − θ(q) is unbounded as q → ζ rapidly. In the long list of 17 mock theta functions given by Ramanujan, few have been interpreted combinatorially. For example, (q) defined by (1.1) below, has been interpreted by Fine. [8] as a generating function for partitions into odd parts without ...

Measurement of the angular distribution of the electron from W {r_arrow} e = {nu} decay, in p pbar at {radical}s = 1.8 TeV, as function of P{sub T}{sup W}

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-06-01

The goal of this work is to study the behavior of the angular distribution of the electron from the decay of the W boson in a specific rest frame of the W, the Collins-Soper frame. More specifically, the parameter {alpha}{sub 2} from the expression d{sigma}/d(P{sub T}{sup W}){sup 2} d cos {theta}* = k(1 + {alpha}{sub 2} cos {theta}* + {alpha}{sup 2}(cos {theta}*){sup 2}), corresponding to the distribution of cos {theta}* in the Collins-Soper frame, was measured. The experimental value of {alpha}P{sub 2} was compared with the predictions made by E. Mirkes [11] who included the radiative QCD perturbations in the weak-interaction B{sub boson} {r_arrow} lepton + lepton. This experimental value was extracted for the first time using knowledge about how the radiative QCD perturbations will modify the predictions given by the Electro-Weak process only.

Effects on atmospherics at 6 kHz and 9 kHz recorded at Tripura during the India-Pakistan Border earthquake

Directory of Open Access Journals (Sweden)

S. S. De

2010-04-01

Full Text Available The outcome of the results of some analyses of electromagnetic emissions recorded by VLF receivers at 6 kHz and 9 kHz over Agartala, Tripura, the North-Eastern state of India (Lat. 23° N, Long. 91.4° E during the large earthquake at Muzaffarabad (Lat. 34.53° N, Long. 73.58° E at Kashmir under Pakistan have been presented here. Spiky variations in integrated field intensity of atmospherics (IFIA at 6 and 9 kHz have been observed 10 days prior (from midnight of 28 September 2005 to the day of occurrence of the earthquake on 8 October 2005 and the effect continued, decayed gradually and eventually ceased on 16 October 2005. The spikes distinctly superimposed on the ambient level with mutual separation of 2–5 min. Occurrence number of spikes per hour and total duration of their occurrence have been found remarkably high on the day of occurrence of the earthquake. The spike heights are higher at 6 kHz than at 9 kHz. The results have been explained on the basis of generation of electromagnetic radiation associated with fracture of rocks, their subsequent penetration into the Earth's atmosphere and finally their propagation between Earth-ionosphere waveguide. The present observation shows that VLF anomaly is well-confined between 6 and 9 kHz.

Lower trait frontal theta activity in mindfulness meditators

Directory of Open Access Journals (Sweden)

Guaraci Ken Tanaka

2014-09-01

Full Text Available Acute and long-term effects of mindfulness meditation on theta-band activity are not clear. The aim of this study was to investigate frontal theta differences between long- and short-term mindfulness practitioners before, during, and after mindfulness meditation. Twenty participants were recruited, of which 10 were experienced Buddhist meditators. Despite an acute increase in the theta activity during meditation in both the groups, the meditators showed lower trait frontal theta activity. Therefore, we suggested that this finding is a neural correlate of the expert practitioners’ ability to limit the processing of unnecessary information (e.g., discursive thought and increase the awareness of the essential content of the present experience. In conclusion, acute changes in the theta band throughout meditation did not appear to be a specific correlate of mindfulness but were rather related to the concentration properties of the meditation. Notwithstanding, lower frontal theta activity appeared to be a trait of mindfulness practices.

Synthesis of nanocrystalline nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films by chemical bath deposition method

Energy Technology Data Exchange (ETDEWEB)

Pawar, D.K. [Department of Chemistry, Shivaji University, Kolhapur 416 004 (M.S.) (India); Pawar, S.M. [Department of Materials Science and Engineering, Chonnam National University, 500 757 (Korea, Republic of); Patil, P.S. [Department of Physics, Shivaji University, Kolhapur 416 004 (M.S.) (India); Kolekar, S.S., E-mail: kolekarss2003@yahoo.co.in [Department of Chemistry, Shivaji University, Kolhapur 416 004 (M.S.) (India)

2011-02-24

Graphical abstract: Display Omitted Research highlights: > We have successfully synthesized nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films on stainless steel substrates using a low temperature chemical bath deposition method. > The surface morphological study showed the compact flakes like morphology. > The as-deposited thin films are hydrophilic (10{sup o} < {theta} < 90{sup o}) whereas the annealed thin films are super hydrophilic ({theta} < 10{sup o}) in nature. > Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films could be used in supercapacitor. - Abstract: The nickel-zinc ferrite (Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}) thin films have been successfully deposited on stainless steel substrates using a chemical bath deposition method from alkaline bath. The films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), static water contact angle and cyclic voltammetry measurements. The X-ray diffraction pattern shows that deposited Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films were oriented along (3 1 1) plane. The FTIR spectra showed strong absorption peaks around 600 cm{sup -1} which are typical for cubic spinel crystal structure. SEM study revealed compact flakes like morphology having thickness {approx}1.8 {mu}m after air annealing. The annealed films were super hydrophilic in nature having a static water contact angle ({theta}) of 5{sup o}.The electrochemical supercapacitor study of Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} thin films has been carried out in 6 M KOH electrolyte. The values of interfacial and specific capacitances obtained were 0.0285 F cm{sup -2} and 19 F g{sup -1}, respectively.

Frontal EEG delta/alpha ratio and screening for post-stroke cognitive deficits: the power of four electrodes.

Science.gov (United States)

Schleiger, Emma; Sheikh, Nabeel; Rowland, Tennille; Wong, Andrew; Read, Stephen; Finnigan, Simon

2014-10-01

This study analysed correlations between post-stroke, quantitative electroencephalographic (QEEG) indices, and cognition-specific, functional outcome measures. Results were compared between QEEG indices calculated from the standard 19 versus 4 frontal (or 4 posterior) electrodes to assess the feasibility and efficacy of employing a reduced electrode montage. Resting-state EEG was recorded at the bedside within 62-101 h after onset of symptoms of middle cerebral artery, ischaemic stroke (confirmed radiologically). Relative power for delta, theta, alpha and beta, delta/alpha ratio (DAR) and pairwise-derived brain symmetry index (pdBSI) were averaged; over all electrodes (global), over F3, F4, F7, F8 (frontal) and P3, P4, T5, T6 (posterior). The functional independence measure and functional assessment measure (FIM-FAM) was administered at mean 105 days post-stroke. Total (30 items) and cognition-specific (5 items) FIM-FAM scores were correlated with QEEG indices using Spearman's coefficient, with a Bonferroni correction. Twenty-five patients were recruited, 4 died within 3 months and 1 was lost to follow-up. Hence 20 cases (10 female; 9 left hemisphere; mean age 68 years, range 38-84) were analysed. Two QEEG indices demonstrated highly-significant correlations with cognitive outcomes: frontal DAR (ρ = -0.664, p ≤ 0.001) and global, relative alpha power (ρ = 0.67, p ≤ 0.001). After correction there were no other significant correlations. Alpha activity - particularly frontally - may index post-stroke attentional capacity, which appears to be a key determinant of functional and cognitive outcomes. Likewise frontal delta pathophysiology influences such outcomes. Pending further studies, DAR from 4 frontal electrodes may inform early screening for post-MCA stroke cognitive deficits, and thereby, clinical decisions. Copyright © 2014 Elsevier B.V. All rights reserved.

Search for the exotic $\\Theta^+$ resonance in the NOMAD experiment

CERN Document Server

Samoylov, O; Autiero, D; Baldisseri, Alberto; Baldo-Ceolin, M; Banner, M; Bassompierre, G; Benslama, K; Besson, N; Bird, I; Blumenfeld, B; Bobisut, F; Bouchez, J; Boyd, S; Bueno, A; Bunyatov, S; Camilleri, L L; Cardini, A; Cattaneo, P W; Cavasinni, V; Cervera-Villanueva, A; Challis, R; Chukanov, A; Collazuol, G; Conforto, G; Conta, C; Contalbrigo, M; Cousins, R; Daniels, D; De Santo, A; Degaudenzi, H M; Del Prete, T; Di Lella, L; Dignan, T; Do Couto e Silva, E; Dumarchez, J; Ellis, M; Feldman, G J; Ferrari, R; Ferrère, D; Flaminio, V; Fraternali, M; Gaillard, J M; Gangler, E; Geiser, A; Geppert, D; Gibin, D; Gninenko, S; Godley, A; Gosset, J; Gouanère, M; Grant, A; Graziani, G; Guglielmi, A M; Gómez-Cadenas, J J; Gössling, C; Hagner, C; Hernando, J; Hubbard, D; Hurst, P; Hyett, N; Iacopini, E; Joseph, C; Juget, F; Kent, N; Kirsanov, M; Klimov, O; Kokkonen, J; Kovzelev, A; Krasnoperov, A V; La Rotonda, L; Lacaprara, S; Lachaud, C; Lakic, B; Lanza, A; Laveder, M; Letessier-Selvon, A A; Linssen, L; Ljubicic, A; Long, J; Lupi, A; Lyubushkin, V; Lévy, J M; Marchionni, A; Martelli, F; Mendiburu, J P; Meyer, J P; Mezzetto, M; Mishra, S R; Moorhead, G F; Méchain, X; Naumov, D; Nefedov, Yu; Nguyen-Mau, C; Nédélec, P; Orestano, D; Pastore, F; Peak, L S; Pennacchio, E; Pessard, H; Petti, R; Placci, A; Polesello, G; Pollmann, D; Polyarush, A Yu; Popov, B; Poulsen, C; Rebuffi, L; Rico, J; Riemann, P; Roda, C; Rubbia, André; Salvatore, F; Schahmaneche, K; Schmidt, B; Schmidt, T; Sconza, A; Sevior, M; Sillou, D; Soler, F J P; Sozzi, G; Steele, D; Stiegler, U; Stipcevic, M; Stolarczyk, T; Tareb-Reyes, M; Taylor, G N; Tereshchenko, V V; Toropin, A; Touchard, A M; Tovey, S N; Tran, M T; Tsesmelis, E; Ulrichs, J; Vacavant, L; Valdata-Nappi, M; Valuev, V; Vannucci, F; Varvell, K E; Veltri, M; Vercesi, V; Vidal-Sitjes, G; Vieira, J M; Vinogradova, T; Weber, F V; Weisse, T; Wilson, F F; Winton, L J; Yabsley, B D; Zaccone, Henri; Zuber, K; Zuccon, P

2007-01-01

A search for exotic Theta baryon via Theta -> proton +Ks decay mode in the NOMAD muon neutrino DIS data is reported. The special background generation procedure was developed. The proton identification criteria are tuned to maximize the sensitivity to the Theta signal as a function of xF which allows to study the Theta production mechanism. We do not observe any evidence for the Theta state in the NOMAD data. We provide an upper limit on Theta production rate at 90% CL as 2.13 per 1000 of neutrino interactions.

The analyzing power Asub(y)[(theta) for 12C(n,nsub(0,1))12C betwen 8.9 and] 14.9 MeV neutron energy

International Nuclear Information System (INIS)

Woye, E.; Tornow, W.; Mack, G.; Clegg, T.B.; Wylie, W.

1983-01-01

The analyzing power Asub(#betta#)(theta) for 12 C(n,n) 12 C elastic scattering and for inelastic scattering to the first excited state (Jsup(π) = 2 + , Q = -4.44 MeV) of 12 C was measured in the energy range from 8.9 to 14.9 MeV in 1 MeV steps. A pulsed polarized neutron beam was produced via the 2 H(d vector,n vector) 3 He polarization transfer reaction. Monte Carlo simulations were used to correct the data for finite geometry and multiple scattering effects. The Asub(#betta#) data, together with publsihed cross-section data, were analyzed in the framework of the spherical optical model and in the coupled-channels formalism. A good description of the data has been achieved. (orig.)

Spatially selective alpha oscillations reveal moment-by-moment trade-offs between working memory and attention

NARCIS (Netherlands)

van Moorselaar, Dirk; Foster, Joshua J.; Sutterer, David W.; Theeuwes, Jan; Olivers, Christian N.L.; Awh, Edward

Current theories assume a functional role for covert attention in the maintenance of spatial information in working memory. Consistent with this view, both the locus of attention and positions stored in working memory can be decoded based on the topography of oscillatory alpha-band (8-12 Hz)

Syndecan-4 associates with alpha-actinin

DEFF Research Database (Denmark)

Greene, Daniel K; Tumova, Sarka; Couchman, John R

2002-01-01

during the formation of focal adhesions. To date, a direct link between syndecan-4 and the cytoskeleton has remained elusive. We now demonstrate by Triton X-100 extraction immunoprecipitation and in vitro binding assays that the focal adhesion component alpha-actinin interacts with syndecan-4 in a beta...

Kinetic description of linear theta-pinch equilibria

International Nuclear Information System (INIS)

Batchelor, D.B.; Davidson, R.C.

1975-01-01

Equilibrium properties of linear theta-pinch plasmas are studied within the framework of the steady-state (o/x=0) Vlasov-Maxwell equations. The analysis is carried out for an infinitely long plasma column aligned parallel to an externally applied axial magnetic field Bsub(z)sup(ext)esub(z). Equilibrium properties are calculated for the class of rigid-rotor Vlasov equilibria, in which the th component distribution function (Hsub(perpendicular), Psub(theta), upsilonsub(z) depends on perpendicular energy H and canonical angular momentum Psub(theta), exclusively through the linear combination Hsub(perpendicular)-ωsub(j)Psub(theta), where ω;=const.=angular velocity of mean rotation. General equilibrium relations that pertain to the entire class of rigid-rotor Vlasov equilibria are discussed; and specific examples of sharp- and diffuse-boundary equilibrium configurations are considered. Rigid-rotor density and magnetic field profiles are compared with experimentally observed profiles. A general prescription is given for determining the functional dependence of the equilibrium distribution function on Hsub(perpendicular)-ωsub(j)Psub(theta) in circumstances, where the density profile or magnetic field profile is specified. (author)

A basic research of gadolinium hydrogen [alpha], [alpha]', [alpha]'', [alpha]'''-tetramethly- 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetate with high complex stability as a contrast agent for MRI

Energy Technology Data Exchange (ETDEWEB)

Seri, Shigemi; Hashiguchi, Yuji; Kubomura, Kan; Abe, Yukiko; Iguchi, Toshio; Iwai, Kumiko [Nihon Medi-Physics Co., Ltd., Sodegaura, Chiba (Japan); Watanabe, Tokuko

1993-05-01

Gadolinium hydrogen [alpha], [alpha]', [alpha]'', [alpha]'''-tetramethyl- 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetate (abbreviated Gd-DOTMA) was developed as a new contrast agent for magnetic resonance imaging. Our study focused on the evaluation of the pharmaceutical properties as in vivo agent. The new modified process by which Gd-DOTMA was synthesized resulted in high yields of this agent. A high stability constant of 10[sup 26] fro Gd-DOTMA was determined at physiological pH. It is more stable than Gd complex with tetraazacyclododecanetetraacetic acid (which is regarded as the most stable Gd complex). The strong T[sub 1] relaxivities of 4.0 and 3.7 (mM [center dot] s)[sup -1] at 0.5 tesla and 1.5 tesla were measured in the aqueous solution. The osmolarity of 0.5 M solution, dissolved with equal amounts of meglumine as a solubilizer is 1020 mOsmol/kg. This contrasting agent was studied in vivo by using rats as the experimental group. The agent showed strong enhancement of transplanted tumors within the rat population studied. This compound is rapidly excreted by the kidneys, and has a half-life of 26 min in blood. The median lethal dose (LD[sub 50] value) of the stable Gd-DOTMA has a favorable tolerance of over 12.3 mmol/kg. (author).

The theta-structure in string theories - 1: bosonic strings

International Nuclear Information System (INIS)

Li Miao.

1985-09-01

We explored the theta-structures in bosonic string theories which are similar to those in gauge field theories. The theta-structure of string is due to the multiply connected spatial compact subspace of space-time. The work of this paper shows that there is an energy band E(theta) in the string theory and one may move the tachyon out in theory by choosing some proper theta parameters. (author)

Increase in posterior alpha activity during rehearsal predicts successful long-term memory formation of word sequences.

NARCIS (Netherlands)

Meeuwissen, E.B.; Takashima, A.; Fernandez, G.S.E.; Jensen, O.

2011-01-01

It is becoming increasingly clear that demanding cognitive tasks rely on an extended network engaging task-relevant areas and, importantly, disengaging task-irrelevant areas. Given that alpha activity (8-12 Hz) has been shown to reflect the disengagement of task-irrelevant regions in attention and

Higher balance task demands are associated with an increase in individual alpha peak frequency

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Thorben eHülsdünker

2016-01-01

Full Text Available Balance control is fundamental for most daily motor activities, and its impairment is associated with an increased risk of falling. Growing evidence suggests the human cortex is essentially contributing to the control of standing balance. However, the exact mechanisms remain unclear and need further investigation. In a previous study we introduced a new protocol to identify electrocortical activity associated with performance of different continuous balance tasks with the eyes opened. The aim of this study was to extend our previous results by investigating the individual alpha peak frequency (iAPF, a neurophysiological marker of thalamo-cortical information transmission, which remained unconsidered so far in balance research. Thirty-seven subjects completed nine balance tasks varying in surface stability and base of support. Electroencephalography (EEG was recorded from 32 scalp locations throughout balancing with the eyes closed to ensure reliable identification of the iAPF. Balance performance was quantified as the sum of anterior-posterior and medio-lateral movements of the supporting platform. The iAPF, as well as power in the theta, lower alpha and upper alpha frequency bands were determined for each balance task after applying an ICA-based artifact rejection procedure. Higher demands on balance control were associated with a global increase in iAPF and a decrease in lower alpha power. These results may indicate increased thalamo-cortical information transfer and general cortical activation, respectively. In addition, a significant increase in upper alpha activity was observed in the fronto-central region whereas it decreased in the centro-parietal region. Furthermore, midline theta increased with higher task demands probably indicating activation of error detection/processing mechanisms. IAPF as well as theta and alpha power were correlated with platform movements. The results provide new insights into spectral and spatial characteristics

Quantum thetas on noncommutative Td with general embeddings

International Nuclear Information System (INIS)

Chang-Young, Ee; Kim, Hoil

2008-01-01

In this paper, we construct quantum theta functions over noncommutative T d with general embeddings. Manin has constructed quantum theta functions from the lattice embedding into vector space x finite group. We extend Manin's construction of quantum thetas to the case of general embedding of vector space x lattice x torus. It turns out that only for the vector space part of the embedding there exists the holomorphic theta vector, while for the lattice part there does not. Furthermore, the so-called quantum translations from embedding into the lattice part become non-additive, while those from the vector space part are additive

Anticonvulsant activity of a mGlu(4alpha) receptor selective agonist, (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid.

Science.gov (United States)

Chapman, A G; Talebi, A; Yip, P K; Meldrum, B S

2001-07-20

The metabotropic Group III agonist, (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid (ACPT-1), selective for the mGlu(4alpha) receptor, suppresses sound-induced seizures in DBA/2 mice following its intracerebroventricular (i.c.v.) administration (ED(50) 5.6 [2.9-10.7], nmol i.c.v., 15 min, clonic phase) and in genetically epilepsy-prone (GEP) rats following focal administration into the inferior colliculus (ED(50) 0.08 [0.01-0.50], nmol, 60 min, clonic phase). ACPT-1 also protects against clonic seizures induced in DBA/2 mice by the Group I agonist, (RS)-3,5-dihydroxyphenylglycine (3,5-DHPG) (ED(50) 0.60 [0.29-1.2], nmol i.c.v.) and by the Group III antagonist, (RS)-alpha-methylserine-O-phosphate (MSOP) (ED(50) 49.3 [37.9-64.1], nmol i.c.v.). Another Group III agonist, (RS)-4-phosphonophenyl-glycine (PPG), preferentially activating the mGlu(8) receptor, previously shown to protect against sound-induced seizures in DBA/2 mice and GEP rats, also protects against seizures induced in DBA/2 by 3,5-DHPG (ED(50) 3.7 [2.4-5.7], nmol i.c.v.) and by the Group III antagonist, MSOP (ED(50) 40.2 [21.0-77.0], nmol i.c.v.). At very high doses (500 nmol i.c.v. and above), Group III antagonists have pro-convulsant and convulsant activity. The anticonvulsant protection against sound-induced seizures in DBA/2 mice provided by a fully protective dose (20 nmol, i.c.v.) of the mGlu(4) receptor agonist ACPT-1, is partially reversed by the co-administration of the Group III antagonists, MSOP, (RS)-alpha-methyl-4-phosphonophenylglycine (MPPG) or (S)-2-amino-2-methyl-4-phosphonobutanoic acid (MAP4), in the 20-50 nmol dose range. At doses of 50-200 nmol, MPPG and MAP4 cause further reversal of the ACPT-1 anticonvulsant protection, while the MSOP effect on ACPT-1 protection is abolished at higher doses. In contrast, the anticonvulsant protection against sound-induced seizures in DBA/2 mice provided by a fully protective dose (20 nmol, i.c.v.) of the mGlu(8) receptor agonist PPG, is not

The Efficacy of Neurofeedback in Patients with Major Depressive Disorder: An Open Labeled Prospective Study.

Science.gov (United States)

Cheon, Eun-Jin; Koo, Bon-Hoon; Choi, Joong-Hyun

2016-03-01

The purpose of this study was to evaluate the effect of neurofeedback on depressive symptoms and electrophysiological disturbances in patients with major depressive disorder. We recruited participants suffering from depression to evaluate efficacy of left prefrontal beta with alpha/theta training. An 8-week, prospective, open-label study was undertaken. Twenty participants were recruited. The treatment protocol was twice or three times a week training of beta at F3 with alpha/theta at Pz for 8 weeks. When every visit, patients were received beta training for 30 min, and then alpha/theta training for 30 min. Baseline, 4 and 8 week scores of; the Hamilton rating scale for Depression (HAM-D), the Hamilton rating scale for Anxiety (HAM-A), the Beck Depression Inventory (BDI)-II, the Beck Anxiety Inventory (BAI), Clinical global impression-severity (CGI-S), and pre- and post-treatment resting state EEGs were compared. Interhemispheric alpha power asymmetry (A score) was computed for homologous sites F3-F4. Pre- and post-training clinical assessments revealed significant improvements in HAM-D, HAM-A, BDI, and CGI-S scores. Cumulative response rates by HAM-D were 35.0 and 75.0 % at 4 and 8 weeks, respectively, corresponding cumulative remission rates by HAM-D were 15.0 and 55.0 %, respectively. No significant differences were found between pre- and post-treatment A score. Neurofeedback treatment could improve depressive symptoms significantly. In addition, anxiety symptoms and clinical illness severity decreased significantly after neurofeedback treatment. Despite its several limitations, such as, small sample size and lack of a control group, this study suggested neurofeedback has significant effects in patients with major depressive disorder.

On the irrationality of Ramanujan's mock theta functions and other q-series at an infinite number of points

OpenAIRE

Mingarelli, Angelo B.

2007-01-01

We show that all of Ramanujan's mock theta functions of order 3, Watson's three additional mock theta functions of order 3, the Rogers-Ramanujan q-series, and 6 mock theta functions of order 5 take on irrational values at the points q=\\pm 1/2,\\pm 1/3,\\pm 1/4,...

Anterior Thalamic High Frequency Band Activity Is Coupled with Theta Oscillations at Rest

Directory of Open Access Journals (Sweden)

Catherine M. Sweeney-Reed

2017-07-01

Full Text Available Cross-frequency coupling (CFC between slow and fast brain rhythms, in the form of phase–amplitude coupling (PAC, is proposed to enable the coordination of neural oscillatory activity required for cognitive processing. PAC has been identified in the neocortex and mesial temporal regions, varying according to the cognitive task being performed and also at rest. PAC has also been observed in the anterior thalamic nucleus (ATN during memory processing. The thalamus is active during the resting state and has been proposed to be involved in switching between task-free cognitive states such as rest, in which attention is internally-focused, and externally-focused cognitive states, in which an individual engages with environmental stimuli. It is unknown whether PAC is an ongoing phenomenon during the resting state in the ATN, which is modulated during different cognitive states, or whether it only arises during the performance of specific tasks. We analyzed electrophysiological recordings of ATN activity during rest from seven patients who received thalamic electrodes implanted for treatment of pharmacoresistant focal epilepsy. PAC was identified between theta (4–6 Hz phase and high frequency band (80–150 Hz amplitude during rest in all seven patients, which diminished during engagement in tasks involving an external focus of attention. The findings are consistent with the proposal that theta–gamma coupling in the ATN is an ongoing phenomenon, which is modulated by task performance.

Long-term plasticity is proportional to theta-activity.

Directory of Open Access Journals (Sweden)

Marian Tsanov

Full Text Available BACKGROUND: Theta rhythm in the hippocampal formation is a main feature of exploratory behaviour and is believed to enable the encoding of new spatial information and the modification of synaptic weights. Cyclic changes of dentate gyrus excitability during theta rhythm are related to its function, but whether theta epochs per se are able to alter network properties of dentate gyrus for long time-periods is still poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: We used low-frequency stimulation protocols that amplify the power of endogenous theta oscillations, in order to estimate the plasticity effect of endogenous theta oscillations on a population level. We found that stimulation-induced augmentation of the theta rhythm is linked to a subsequent increase of neuronal excitability and decrease of the synaptic response. This EPSP-to-Spike uncoupling is related to an increased postsynaptic spiking on the positive phases of theta frequency oscillations. Parallel increase of the field EPSP slope and the population spike occurs only after concurrent pre- and postsynaptic activation. Furthermore, we observed that long-term potentiation (>24 h occurs in the dentate gyrus of freely behaving adult rats after phasic activity of entorhinal afferents in the theta-frequency range. This plasticity is proportional to the field bursting activity of granule cells during the stimulation, and may comprise a key step in spatial information transfer. Long-term potentiation of the synaptic component occurs only when the afferent stimulus precedes the evoked population burst, and is input-specific. CONCLUSIONS/SIGNIFICANCE: Our data confirm the role of the dentate gyrus in filtering information to the subsequent network during the activated state of the hippocampus.

Increase in posterior alpha activity during rehearsal predicts successful long-term memory formation of word sequences

NARCIS (Netherlands)

Meeuwissen, E.B.; Takashima, A.; Fernandez, G.S.E.; Jensen, O.

2011-01-01

It is becoming increasingly clear that demanding cognitive tasks rely on an extended network engaging task-relevant areas and, importantly, disengaging task-irrelevant areas. Given that alpha activity (8–12 Hz) has been shown to reflect the disengagement of task-irrelevant regions in attention and

Combinatorial identities for tenth order mock theta functions

Indian Academy of Sciences (India)

44

which lead us to one 4-way and one 3-way combinatorial identity. ... mock theta functions, partition identities and different combinatorial parameters, see for ... 3. Example 1.1. There are twelve (n + 1)–color partitions of 2: 21, 21 + 01, 11 + 11, ...

Ramanujan's theta functions

CERN Document Server

Cooper, Shaun

2017-01-01

Theta functions were studied extensively by Ramanujan. This book provides a systematic development of Ramanujan’s results and extends them to a general theory. The author’s treatment of the subject is comprehensive, providing a detailed study of theta functions and modular forms for levels up to 12. Aimed at advanced undergraduates, graduate students, and researchers, the organization, user-friendly presentation, and rich source of examples, lends this book to serve as a useful reference, a pedagogical tool, and a stimulus for further research. Topics, especially those discussed in the second half of the book, have been the subject of much recent research; many of which are appearing in book form for the first time. Further results are summarized in the numerous exercises at the end of each chapter.

Comparison of Sensorimotor Rhythm (SMR and Beta Training on Selective Attention and Symptoms in Children with Attention Deficit/Hyperactivity Disorder (ADHD: A Trend Report

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Mohammad Reza Mohammadi

2015-11-01

Full Text Available  Objective: The aim of this study was to assess and compare the effect of two neurofeedback protocols (SMR/theta and beta/theta on ADHD symptoms, selective attention and EEG (electroencephalogram parameters in children with ADHD.  Method:The sample consisted of 16 children (9-15 year old: 13 boys; 3 girls with ADHD-combined type (ADHD-C. All of children used methylphenidate (MPH during the study. The neurofeedback training consisted of two phases of 15 sessions, each lasting 45 minutes. In the first phase, participants were trained to enhance sensorimotor rhythm (12-15 Hz and reduce theta activity (4-8 Hz at C4 and in the second phase; they had to increase beta (15-18 Hz and reduce theta activity at C3. Assessments consisted of d2 attention endurance test, ADHD rating scale (parent form at three time periods: before, middle and the end of the training. EEG signals were recorded just before and after the training . Result:Based on parents’ reports, inattention after beta/theta training, and hyperactivity/impulsivity were improved after the end of the training. All subscales of d2 test were improved except for the difference between maximum and minimum responses. However, EEG analysis showed no significant differences . Conclusion:Neurofeedback in conjunction with Methylphenidate may cause further improvement in ADHD symptoms reported by parents and selective attention without long-term impact on EEG patterns. However, determining the exact relationship between EEG parameters, neurofeedback protocols and ADHD symptoms remain unclear.

Quantum Thetas on Noncommutative T^d with General Embeddings

OpenAIRE

Chang-Young, Ee; Kim, Hoil

2007-01-01

In this paper we construct quantum theta functions over noncommutative T^d with general embeddings. Manin has constructed quantum theta functions from the lattice embedding into vector space x finite group. We extend Manin's construction of quantum thetas to the case of general embedding of vector space x lattice x torus. It turns out that only for the vector space part of the embedding there exists the holomorphic theta vector, while for the lattice part there does not. Furthermore, the so-c...

Distributed attention Is implemented through theta-rhythmic gamma modulation

NARCIS (Netherlands)

Landau, A.N.; Schreyer, H.M.; Pelt, S. van; Fries, P.

2015-01-01

When subjects monitor a single location, visual target detection depends on the pre-target phase of an ∼8 Hz brain rhythm [1 and 2]. When multiple locations are monitored, performance decrements suggest a division of the 8 Hz rhythm over the number of locations [3], indicating that different

Neurophysiological correlates of artistic image creation by representatives of artistic professions

Directory of Open Access Journals (Sweden)

Dikaya L. A.

2016-12-01

Full Text Available The steadily increasing demand for artistic professions brings to the fore the task of studying the phenomenon of art by researching the unique capacity of the human brain to create works of art in different spheres of creative activity. So far, only a few studies have investigated creativity-related brain activity in representatives of the creative professions. The aim of the empirical research was to study the neurophysiological correlates of artistic image creation by representatives of the artistic professions. The participants were 60 right-handed females aged 23-27, divided into three groups— artists (23 people, actors (17 people, and specialists who do not work in an artistic field (20 people. The mono-typing technique was used to model the creative artistic process. EEG signals were recorded in a resting state, and during four stages of the creation of an artistic image (viewing of monotypes, frustration, image creation, and thinking over the details from 21 electrodes set on the scalp according to the International 10-20 System. We analyzed EEG coherence for each functional trial at theta (4.00–8.00 Hz, alpha1 (8.00–10.5 Hz, alpha2 (10.5–13.00 Hz, and beta (13.00– 35.00 Hz frequency bands. For statistical analysis, we used MANOVA and post hoc analysis. We found that the neurophysiological correlates of creating an artistic image are different at different stages of the creative process, and have different features for artists and actors. The actors primarily show dominance of right hemisphere activity, while close interaction of the hemispheres distinguishes the brains of the artists. The differences revealed in brain cortex functioning when artists or actors create an artistic image reflect different strategies of imaginative creative work by representatives of these professions.

Interval analysis of interictal EEG: pathology of the alpha rhythm in focal epilepsy

Science.gov (United States)

Pyrzowski, Jan; Siemiński, Mariusz; Sarnowska, Anna; Jedrzejczak, Joanna; Nyka, Walenty M.

2015-11-01

The contemporary use of interictal scalp electroencephalography (EEG) in the context of focal epilepsy workup relies on the visual identification of interictal epileptiform discharges. The high-specificity performance of this marker comes, however, at a cost of only moderate sensitivity. Zero-crossing interval analysis is an alternative to Fourier analysis for the assessment of the rhythmic component of EEG signals. We applied this method to standard EEG recordings of 78 patients divided into 4 subgroups: temporal lobe epilepsy (TLE), frontal lobe epilepsy (FLE), psychogenic nonepileptic seizures (PNES) and nonepileptic patients with headache. Interval-analysis based markers were capable of effectively discriminating patients with epilepsy from those in control subgroups (AUC~0.8) with diagnostic sensitivity potentially exceeding that of visual analysis. The identified putative epilepsy-specific markers were sensitive to the properties of the alpha rhythm and displayed weak or non-significant dependences on the number of antiepileptic drugs (AEDs) taken by the patients. Significant AED-related effects were concentrated in the theta interval range and an associated marker allowed for identification of patients on AED polytherapy (AUC~0.9). Interval analysis may thus, in perspective, increase the diagnostic yield of interictal scalp EEG. Our findings point to the possible existence of alpha rhythm abnormalities in patients with epilepsy.

The annihilation of ortho-positronium in the {alpha} and {beta} cavities of the 4A zeolite and those CoZ4A and MnZ4A; La aniquilacion del orto-positronio en las cavidades {alpha} y {beta} de la zeolita 4A y en las de CoZ4A y MnZ4A

Energy Technology Data Exchange (ETDEWEB)

Cabral P, A.; Garcia S, I.; Jimenez B, J.; Solache R, M.; Bonifacio M, J.; Rodriguez F, C.; Bulbulian, S. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

2002-07-01

The lifetime of the ortho-positronium in the zeolite 4A, partially dehydrated, changes to three characteristic modes. The first mode could be associated with the water elimination of the small {beta} cavity of this zeolite. At the end of this first dehydration process it is estimated a cavity radius, R = 33.8 nm. The other two types of variation of lifetime of ortho-positronium would be associated with the water elimination of the {alpha} great cavity and of the rest of the zeolite. From the zeolite 4A totally dehydrated and of the zeolite 4A exchanged with Co (II) and MN (II), also dehydrated radius are respectively determined for the {alpha} great cavity of R = 48.1, 54.5 and 56.5 nm. (Author)

Transcranial electrical currents to probe EEG brain rhythms and memory consolidation during sleep in humans.

Directory of Open Access Journals (Sweden)

Lisa Marshall

Full Text Available Previously the application of a weak electric anodal current oscillating with a frequency of the sleep slow oscillation (∼0.75 Hz during non-rapid eye movement sleep (NonREM sleep boosted endogenous slow oscillation activity and enhanced sleep-associated memory consolidation. The slow oscillations occurring during NonREM sleep and theta oscillations present during REM sleep have been considered of critical relevance for memory formation. Here transcranial direct current stimulation (tDCS oscillating at 5 Hz, i.e., within the theta frequency range (theta-tDCS is applied during NonREM and REM sleep. Theta-tDCS during NonREM sleep produced a global decrease in slow oscillatory activity conjoint with a local reduction of frontal slow EEG spindle power (8-12 Hz and a decrement in consolidation of declarative memory, underlining the relevance of these cortical oscillations for sleep-dependent memory consolidation. In contrast, during REM sleep theta-tDCS appears to increase global gamma (25-45 Hz activity, indicating a clear brain state-dependency of theta-tDCS. More generally, results demonstrate the suitability of oscillating-tDCS as a tool to analyze functions of endogenous EEG rhythms and underlying endogenous electric fields as well as the interactions between EEG rhythms of different frequencies.

The delta-opioid receptor agonist SNC80 [(+)-4-[alpha(R)-alpha-[(2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl]-(3-methoxybenzyl)-N,N-diethylbenzamide] synergistically enhances the locomotor-activating effects of some psychomotor stimulants, but not direct dopamine agonists, in rats.

Science.gov (United States)

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

2008-02-01

The nonpeptidic delta-opioid agonist SNC80 [(+)-4-[alpha(R)-alpha-[(2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl]-(3-methoxybenzyl)-N,N-diethylbenzamide] produces many stimulant-like behavioral effects in rodents and monkeys, such as locomotor stimulation, generalization to cocaine in discrimination procedures, and antiparkinsonian effects. Tolerance to the locomotor-stimulating effects of SNC80 develops after a single administration of SNC80 in rats; it is not known whether cross-tolerance develops to the effects of other stimulant compounds. In the initial studies to determine whether SNC80 produced cross-tolerance to other stimulant compounds, it was discovered that amphetamine-stimulated locomotor activity was greatly enhanced in SNC80-pretreated rats. This study evaluated acute cross-tolerance between delta-opioid agonists and other locomotor-stimulating drugs. Locomotor activity was measured in male Sprague-Dawley rats implanted with radiotransmitters, and activity levels were recorded in the home cage environment. Three-hour SNC80 pretreatment produced tolerance to further delta-opioid receptor stimulation but also augmented greatly amphetamine-stimulated locomotor activity in a dose-dependent manner. Pretreatments with other delta-opioid agonists, (+)BW373U86 [(+)-4-[alpha(R)-alpha-[(2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl]-3-hydroxybenzyl]-N,N-diethylbenzamide] and oxymorphindole (17-methyl-6,7-dehydro-4,5-epoxy-3,14-dihydroxy-6,7,2',3'-indolomorphinan), also modified amphetamine-induced activity levels. SNC80 pretreatment enhanced the stimulatory effects of the dopamine/norepinephrine transporter ligands cocaine and nomifensine (1,2,3,4-tetrahydro-2-methyl-4-phenyl-8-isoquinolinanmine maleate salt), but not the direct dopamine receptor agonists SKF81297 [R-(+)-6-chloro-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide] and quinpirole [trans-(-)-(4alphaR)-4,4a, 5,6,7,8,8a,9-octahydro-5-propyl-1H-pyrazolo[3,4-g] quinoline

Impairment of cognitive function and synaptic plasticity associated with alteration of information flow in theta and gamma oscillations in melamine-treated rats.

Directory of Open Access Journals (Sweden)

Xiaxia Xu

Full Text Available Changes of neural oscillations at a variety of physiological rhythms are effectively associated with cognitive performance. The present study investigated whether the directional indices of neural information flow (NIF could be used to symbolize the synaptic plasticity impairment in hippocampal CA3-CA1 network in a rat model of melamine. Male Wistar rats were employed while melamine was administered at a dose of 300 mg/kg/day for 4 weeks. Behavior was measured by the Morris water maze(MWMtest. Local field potentials (LFPs were recorded before long-term potentiation (LTP induction. Generalized partial directed coherence (gPDC and phase-amplitude coupling conditional mutual information (PAC_CMI were used to measure the unidirectional indices in both theta and low gamma oscillations (LG, ~ 30-50 Hz. Our results showed that melamine induced the cognition deficits consistent with the reduced LTP in CA1 area. Phase locking values (PLVs showed that the synchronization between CA3 and CA1 in both theta and LG rhythms was reduced by melamine. In both theta and LG rhythms, unidirectional indices were significantly decreased in melamine treated rats while a similar variation trend was observed in LTP reduction, implying that the effects of melamine on cognitive impairment were possibly mediated via profound alterations of NIF on CA3-CA1 pathway in hippocampus. The results suggested that LFPs activities at these rhythms were most likely involved in determining the alterations of information flow in the hippocampal CA3-CA1 network, which might be associated with the alteration of synaptic transmission to some extent.

The effect of alpha incident- and poloidal-angle distributions on blister-induced first-wall erosion

International Nuclear Information System (INIS)

Fenske, G.; Hively, L.; Miley, G.

1979-01-01

The incident velocity distribution of high-energy alpha particles bombarding the first wall of an axisymmetric tokamak is evaluated as a function of poloidal angle (theta). The resulting helium concentration profile as a function of the poloidal angle and the implant depth is calculated for a typical Experimental Power Reactor (EPR) design. The critical helium concentration for blistering is first exceeded at theta approx. 55 0 . Peak concentrations are reduced somewhat through continuous D-T sputtering which, dependent on theta, reduces the blister skin thicknesses. The blistering-induced impurity level is found to increase drastically (< approx. 50%), relative to sputtering-induced impurities, at periodic intervals corresponding to approx. 4000 hours operation when each generation of blister begins to exfoliate. (orig.)

Early Changes in Alpha Band Power and DMN BOLD Activity in Alzheimer’s Disease: A Simultaneous Resting State EEG-fMRI Study

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Katharina Brueggen

2017-10-01

Full Text Available Simultaneous resting state functional magnetic resonance imaging (rsfMRI–resting state electroencephalography (rsEEG studies in healthy adults showed robust positive associations of signal power in the alpha band with BOLD signal in the thalamus, and more heterogeneous associations in cortical default mode network (DMN regions. Negative associations were found in occipital regions. In Alzheimer’s disease (AD, rsfMRI studies revealed a disruption of the DMN, while rsEEG studies consistently reported a reduced power within the alpha band. The present study is the first to employ simultaneous rsfMRI-rsEEG in an AD sample, investigating the association of alpha band power and BOLD signal, compared to healthy controls (HC. We hypothesized to find reduced positive associations in DMN regions and reduced negative associations in occipital regions in the AD group. Simultaneous resting state fMRI–EEG was recorded in 14 patients with mild AD and 14 HC, matched for age and gender. Power within the EEG alpha band (8–12 Hz, 8–10 Hz, and 10–12 Hz was computed from occipital electrodes and served as regressor in voxel-wise linear regression analyses, to assess the association with the BOLD signal. Compared to HC, the AD group showed significantly decreased positive associations between BOLD signal and occipital alpha band power in clusters in the superior, middle and inferior frontal cortex, inferior temporal lobe and thalamus (p < 0.01, uncorr., cluster size ≥ 50 voxels. This group effect was more pronounced in the upper alpha sub-band, compared to the lower alpha sub-band. Notably, we observed a high inter-individual heterogeneity. Negative associations were only reduced in the lower alpha range in the hippocampus, putamen and cerebellum. The present study gives first insights into the relationship of resting-state EEG and fMRI characteristics in an AD sample. The results suggest that positive associations between alpha band power and BOLD

Theta-Gamma Coupling and Working Memory in Alzheimer’s Dementia and Mild Cognitive Impairment

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Michelle S. Goodman

2018-04-01

Full Text Available Working memory deficits are common among individuals with Alzheimer’s dementia (AD or mild cognitive impairment (MCI. Yet, little is known about the mechanisms underlying these deficits. Theta-gamma coupling—the modulation of high-frequency gamma oscillations by low-frequency theta oscillations—is a neurophysiologic process underlying working memory. We assessed the relationship between theta-gamma coupling and working memory deficits in AD and MCI. We hypothesized that: (1 individuals with AD would display the most significant working memory impairments followed by MCI and finally healthy control (HC participants; and (2 there would be a significant association between working memory performance and theta-gamma coupling across all participants. Ninety-eight participants completed the N-back working memory task during an electroencephalography (EEG recording: 33 with AD (mean ± SD age: 76.5 ± 6.2, 34 with MCI (mean ± SD age: 74.8 ± 5.9 and 31 HCs (mean ± SD age: 73.5 ± 5.2. AD participants performed significantly worse than control and MCI participants on the 1- and 2-back conditions. Regarding theta-gamma coupling, AD participants demonstrated the lowest level of coupling followed by the MCI and finally control participants on the 2-back condition. Finally, a linear regression analysis demonstrated that theta-gamma coupling (β = 0.69, p < 0.001 was the most significant predictor of 2-back performance. Our results provide evidence for a relationship between altered theta-gamma coupling and working memory deficits in individuals with AD and MCI. They also provide insight into a potential mechanism underlying working memory impairments in these individuals.

Dysregulated corticostriatal activity in open-field behavior and the head-twitch response induced by the hallucinogen 2,5-dimethoxy-4-iodoamphetamine.

Science.gov (United States)

Rangel-Barajas, Claudia; Estrada-Sánchez, Ana María; Barton, Scott J; Luedtke, Robert R; Rebec, George V

2017-02-01

The substituted amphetamine, 2,5-dimethoxy-4-iodoamphetamine (DOI), is a hallucinogen that has been used to model a variety of psychiatric conditions. Here, we studied the effect of DOI on neural activity recorded simultaneously in the primary motor cortex (M1) and dorsal striatum of freely behaving FvB/N mice. DOI significantly decreased the firing rate of individually isolated neurons in M1 and dorsal striatum relative to pre-drug baseline. It also induced a bursting pattern of activity by increasing both the number of spikes within a burst and burst duration. In addition, DOI increased coincident firing between simultaneously recorded neuron pairs within the striatum and between M1 and dorsal striatum. Local field potential (LFP) activity also increased in coherence between M1 and dorsal striatum after DOI in the low frequency gamma band (30-50 Hz), while corticostriatal coherence in delta, theta, alpha, and beta activity decreased. We also assessed corticostriatal LFP activity in relation to the DOI-induced head-twitch response (HTR), a readily identifiable behavior used to assess potential treatments for the conditions it models. The HTR was associated with increased delta and decreased theta power in both M1 and dorsal striatum. Together, our results suggest that DOI dysregulates corticostriatal communication and that the HTR is associated with this dysregulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evoked traveling alpha waves predict visual-semantic categorization-speed

Science.gov (United States)

Fellinger, Robert; Gruber, Walter; Zauner, Andrea; Freunberger, Roman; Klimesch, Wolfgang

2012-01-01

In the present study we have tested the hypothesis that evoked traveling alpha waves are behaviorally significant. The results of a visual-semantic categorization task show that three early ERP components including the P1–N1 complex had a dominant frequency characteristic in the alpha range and behaved like traveling waves do. They exhibited a traveling direction from midline occipital to right lateral parietal sites. Phase analyses revealed that this traveling behavior of ERP components could be explained by phase-delays in the alpha but not theta and beta frequency range. Most importantly, we found that the speed of the traveling alpha wave was significantly and negatively correlated with reaction time indicating that slow traveling speed was associated with fast picture-categorization. We conclude that evoked alpha oscillations are functionally associated with early access to visual-semantic information and generate – or at least modulate – the early waveforms of the visual ERP. PMID:22100769

4-(ALPHA, ALPHA-DIMETHYLBENZYL)PHENYL METHACRYLATE .3. SYNTHESIS, TACTICITY AND GLASS-TRANSITION TEMPERATURES OF ITS POLYMERS

NARCIS (Netherlands)

VANEKENSTEIN, GORA; TAN, YY

Depending on the kind of initiator, anionic Polymerization of 4-(alpha,alpha-dimethylbenzyl)phenyl methacrylate in toluene at -78-degrees-C led either to highly isotactic or predominantly syndiotactic polymers as determined by C-13 NMR spectro copy. The glass transition temperature difference

Leptogenesis, $\\mu - \\tau$ Symmetry and $\\theta_{13}$

CERN Document Server

Mohapatra, Rabindra N; Yu, H; Yu, Haibo

2005-01-01

We show that in theories where neutrino masses arise from type I seesaw formula with three right handed neutrinos and where large atmospheric mixing angle owes its origin to an approximate leptonic $\\mu-\\tau$ interchange symmetry, the primordial lepton asymmetry of the Universe, $\\epsilon_l$ can be expressed in a simple form in terms of low energy neutrino oscillation parameters as $\\epsilon_l = (a \\Delta m^2_\\odot+ b \\Delta m^2_A \\theta^2_{13})$, where $a$ and $b$ are parameters characterizing high scale physics and are each of order $\\leq 10^{-2} $ eV$^{-2}$. We also find that for the case of two right handed neutrinos, $\\epsilon_l \\propto \\theta^2_{13}$ as a result of which, the observed value of baryon to photon ratio implies a lower limit on $\\theta_{13}$. For specific choices of the CP phase $\\delta$ we find $\\theta_{13}$ is predicted to be between $0.10-0.15$.

First-order differential-delay equation for the baroreflex predicts the 0.4-Hz blood pressure rhythm in rats.

Science.gov (United States)

Burgess, D E; Hundley, J C; Li, S G; Randall, D C; Brown, D R

1997-12-01

We have described a 0.4-Hz rhythm in renal sympathetic nerve activity (SNA) that is tightly coupled to 0.4-Hz oscillations in blood pressure in the unanesthetized rat. In previous work, the relationship between SNA and fluctuations in mean arterial blood pressure (MAP) was described by a set of two first-order differential equations. We have now modified our earlier model to test the feasibility that the 0.4-Hz rhythm can be explained by the baroreflex without requiring a neural oscillator. In this baroreflex model, a linear feedback term replaces the sympathetic drive to the cardiovascular system. The time delay in the feedback loop is set equal to the time delay on the efferent side, approximately 0.5 s (as determined in the initial model), plus a time delay of 0.2 s on the afferent side for a total time delay of approximately 0.7 s. A stability analysis of this new model yields feedback resonant frequencies close to 0.4 Hz. Because of the time delay in the feedback loop, the proportional gain may not exceed a value on the order of 10 to maintain stability. The addition of a derivative feedback term increases the system's stability for a positive range of derivative gains. We conclude that the known physiological time delay for the sympathetic portion of the baroreflex can account for the observed 0.4-Hz rhythm in rat MAP and that the sensitivity of the baroreceptors to the rate of change in blood pressure, as well as average blood pressure, would enhance the natural stability of the baroreflex.

Electrical insulators for the theta-pinch fusion reactor

International Nuclear Information System (INIS)

Clinard, F.W. Jr.

1976-01-01

The five major applications for electrical insulators in the Reference Theta Pinch Reactor are as follows: (1) first-wall insulator, (2) blanket intersegment insulator, (3) graphite encapsulating insulator, (4) implosion coil insulator, and (5) compression coil insulator. Insulator design proposals and some preliminary test results are given for each application

Theta function identities associated with Ramanujan's modular ...

Indian Academy of Sciences (India)

In Chapter 20 of his second notebook [6], Ramanujan recorded several theta function identities associated with modular equations of composite degree 15. These identities have previously been proved by Berndt in [3]. But he proved most of these theta function identities using modular equations. These identities can also ...

Determination of uranium concentrations and "2"3"4U/"2"3"8U activity ratio in some granitic rock samples by alpha spectrometry: application of a radiochemical procedure

International Nuclear Information System (INIS)

Khattab, Mahmoud R.

2016-01-01

The present study is an application of a radiochemical procedure using alpha spectrometry technique for determination of uranium isotopes "2"3"8U, "2"3"4U and "2"3"5U on 13 granitic samples. These samples were collected from Gabal Gattar area, Northeastern Desert, Egypt. The collected samples were digested using microwave technique with aqua regia and spiked with "2"3"2U for chemical yield and activity calculation. Separation of uranium isotopes from the samples was done by Dowex 1 x 4 (50-100 mesh) resin followed by source preparation using microprecipitation technique. The concentrations of "2"3"8U were ranged between 28.9±0.9 and 134.8±1.8 Bq/g, and the "2"3"4U concentrations were between 24±0.6 and 147.7±2.2 Bq/g. For the "2"3"5U, the activity concentrations were between 1.3±0.2 and 6.7±1.2 Bq/g. The activity ratio of "2"3"4U/"2"3"8U was calculated and varied from 0.80 to 1.30. (author)

NICER Discovers mHz Oscillations and Marginally Stable Burning in GS 1826-24

Science.gov (United States)

Strohmayer, Tod E.; Gendreau, Keith C.; Keek, Laurens; Bult, Peter; Mahmoodifar, Simin; Chakrabarty, Deepto; Arzoumanian, Zaven; NICER Science Team

2018-01-01

To date, marginally stable thermonuclear burning, evidenced as mHz X-ray flux oscillations, has been observed in only five accreting neutron star binaries, 4U 1636-536, 4U 1608-52, Aql X-1, 4U 1323-619 and Terzan 5 X-2. Here we report the discovery with NASA's Neutron Star Interior Composition Explorer (NICER) of such oscillations from the well-known X-ray burster GS 1826-24. NICER observed GS 1826-24 on 9 September, 2017 for a total exposure of about 4 ksec. Timing analysis revealed highly significant oscillations at a frequency of 8.2 mHz in two successive pointings. The oscillations have a fractional modulation amplitude of approximately 3% for photon energies less than 6 keV. The observed frequency is consistent with the range observed in the other mHz QPO systems, and indeed is slightly higher than the frequency measured in 4U 1636-536 below which mHz oscillations ceased and unstable burning (X-ray bursts) resumed. We discuss the mass accretion rate dependence of the oscillations as well as the X-ray spectrum as a function of pulsation phase. We place the observations in the context of the current theory of marginally stable burning and briefly discuss the potential for constraining neutron star properties using mHz oscillations.

Synthesis and evaluation of phytotoxic activity of {alpha}-Santonin derivatives; Sintese e avaliacao da atividade fitotoxica de derivados da {alpha}-Santonina

Energy Technology Data Exchange (ETDEWEB)

Alvarenga, Elson S.; Barbosa, Luiz C.A.; Saliba, William A.; Arantes, Francisco F.P.; Demuner, Antonio J. [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Quimica]. E-mail: elson@ufv.br; Silva, Antonio A. [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Fitotecnia

2009-07-01

Mixtures of {alpha}-Santonin and various solvents were irradiated by either high or low pressure mercury lamps. The photochemical reactions afforded lumisantonin (11) (76% in acetonitrile), (3 S,3a S,9{beta}S)-3,6,6-trimethyl-3,3a,4,5-tetrahydronafto[1,2-b]furan-2,7({eta}6,9{beta}{eta}) dione (12) (100% in acetonitrile), 10{alpha}-acetoxy-3-oxo-1,7{alpha}H{eta},6,11{alpha}a{eta}-guaia-4-en-6,12-oli= de (8) (26% in acetic acid), 10{alpha}-hydroxy-3-oxo-1,7{alpha}a{eta},6,11{alpha}{eta}-guaia-4-en-6,12-olid= e (10) (32%) and (E)-3-((3 S,3a S,7{alpha}S)-3-methyl-2-oxo-6-(propan-2-ylidene)hexahydrobenzofuran- 7 - (7{alpha}{eta})-ylidene)propanoic acid (9) (44%) (in water/ acetic acid 1:1, v/v). Lactone 12 was also prepared by irradiation of lumisantonin in diethyl ether. Lactones 8 and 10 were converted, respectively, into the 10 {alpha}-acetoxy-3{alpha}-hydroxy-1,7{alpha}H,6,11{alpha}H-guaia-4-en-6,12-olid= e (13) (87%) and 3a,10a-dihydroxy-1,7{alpha}H,6,11{alpha}H-guaia-4-en-6,12-olide (14) (75%) by sodium borohydride reduction. The effects of the compounds on the development of radicle of Sorghum bicolor and Cucumis sativus were evaluated. (author)

Effects of somatosensory electrical stimulation on motor function and cortical oscillations.

Science.gov (United States)

Tu-Chan, Adelyn P; Natraj, Nikhilesh; Godlove, Jason; Abrams, Gary; Ganguly, Karunesh

2017-11-13

Few patients recover full hand dexterity after an acquired brain injury such as stroke. Repetitive somatosensory electrical stimulation (SES) is a promising method to promote recovery of hand function. However, studies using SES have largely focused on gross motor function; it remains unclear if it can modulate distal hand functions such as finger individuation. The specific goal of this study was to monitor the effects of SES on individuation as well as on cortical oscillations measured using EEG, with the additional goal of identifying neurophysiological biomarkers. Eight participants with a history of acquired brain injury and distal upper limb motor impairments received a single two-hour session of SES using transcutaneous electrical nerve stimulation. Pre- and post-intervention assessments consisted of the Action Research Arm Test (ARAT), finger fractionation, pinch force, and the modified Ashworth scale (MAS), along with resting-state EEG monitoring. SES was associated with significant improvements in ARAT, MAS and finger fractionation. Moreover, SES was associated with a decrease in low frequency (0.9-4 Hz delta) ipsilesional parietomotor EEG power. Interestingly, changes in ipsilesional motor theta (4.8-7.9 Hz) and alpha (8.8-11.7 Hz) power were significantly correlated with finger fractionation improvements when using a multivariate model. We show the positive effects of SES on finger individuation and identify cortical oscillations that may be important electrophysiological biomarkers of individual responsiveness to SES. These biomarkers can be potential targets when customizing SES parameters to individuals with hand dexterity deficits. NCT03176550; retrospectively registered.

Application of a TNF-alpha-inhibitor into the scala tympany after cochlear electrode insertion trauma in guinea pigs: preliminary audiologic results.

Science.gov (United States)

Ihler, Friedrich; Pelz, Sabrina; Coors, Melanie; Matthias, Christoph; Canis, Martin

2014-11-01

Cochlear implantation trauma causes both macroscopic and inflammatory trauma. The aim of the present study was to evaluate the effectiveness of the TNF-alpha inhibitor etanercept applied after cochlear implantation trauma on the preservation of acoustic hearing. Guinea pigs were randomly assigned to three groups receiving cochlear implantation trauma by cochleostomy. In one group, the site was sealed by bone cement with no further treatment. A second group was additionally implanted with an osmotic minipump delivering artificial perilymph into the scala tympani for seven days. In the third group, etanercept 1 mg/ml was added to artificial perilymph. Hearing was assessed by auditory brainstem responses at 2, 4, 6, and 8 kHz prior to and after surgery and on days 3, 5, 7, 14, 28. Fifteen healthy guinea pigs. The trauma led to threshold shifts from 50.3 dB ± 16.3 dB to 68.0 dB ± 19.3 dB. Hearing thresholds were significantly lower in etanercept-treated animals compared to controls on day 28 at 8 kHz and from day 3 onwards at 4 and 2 kHz (p < 0.01; two-way RM ANOVA / Bonferroni t-test). The application of etanercept led to preservation of acoustic hearing after cochlear implantation trauma.

Analyzing power Asub(y)((theta) for /sup 12/C(n,nsub(0,1))/sup 12/C betwen 8. 9 and) 14. 9 MeV neutron energy

Energy Technology Data Exchange (ETDEWEB)

Woye, E.; Tornow, W.; Mack, G. (Tuebingen Univ. (Germany, F.R.). Physikalisches Inst.); Floyd, C.E.; Guss, P.P.; Murphy, K.; Byrd, R.C.; Wender, S.A.; Walter, R.L. (Duke Univ., Durham, NC (USA). Dept. of Physics; Triangle Universities Nuclear Lab., Durham, NC (USA))

1983-02-01

The analyzing power Asub(..gamma..)(theta) for /sup 12/C(n,n)/sup 12/C elastic scattering and for inelastic scattering to the first excited state (Jsup(..pi..) = 2/sup +/, Q = -4.44 MeV) of /sup 12/C was measured in the energy range from 8.9 to 14.9 MeV in 1 MeV steps. A pulsed polarized neutron beam was produced via the /sup 2/H(d vector,n vector)/sup 3/He polarization transfer reaction. Monte Carlo simulations were used to correct the data for finite geometry and multiple scattering effects. The Asub(..gamma..) data, together with publsihed cross-section data, were analyzed in the framework of the spherical optical model and in the coupled-channels formalism. A good description of the data has been achieved.

Lee weight enumerators of self-dual codes and theta functions

NARCIS (Netherlands)

Asch, van A.G.; Martens, F.J.L.

2008-01-01

The theory of modular forms, in particular theta functions, and coding theory are in a remarkable way connected. The connection is established by defining a suitable lattice corresponding to the given code, and considering its theta function. First we define some special theta functions, and

Lack of Responsiveness during the Onset and Offset of Sevoflurane Anesthesia Is Associated with Decreased Awake-Alpha Oscillation Power

Directory of Open Access Journals (Sweden)

Kara J. Pavone

2017-05-01

Full Text Available Anesthetic drugs are typically administered to induce altered states of arousal that range from sedation to general anesthesia (GA. Systems neuroscience studies are currently being used to investigate the neural circuit mechanisms of anesthesia-induced altered arousal states. These studies suggest that by disrupting the oscillatory dynamics that are associated with arousal states, anesthesia-induced oscillations are a putative mechanism through which anesthetic drugs produce altered states of arousal. However, an empirical clinical observation is that even at relatively stable anesthetic doses, patients are sometimes intermittently responsive to verbal commands during states of light sedation. During these periods, prominent anesthesia-induced neural oscillations such as slow-delta (0.1–4 Hz oscillations are notably absent. Neural correlates of intermittent responsiveness during light sedation have been insufficiently investigated. A principled understanding of the neural correlates of intermittent responsiveness may fundamentally advance our understanding of neural dynamics that are essential for maintaining arousal states, and how they are disrupted by anesthetics. Therefore, we performed a high-density (128 channels electroencephalogram (EEG study (n = 8 of sevoflurane-induced altered arousal in healthy volunteers. We administered temporally precise behavioral stimuli every 5 s to assess responsiveness. Here, we show that decreased eyes-closed, awake-alpha (8–12 Hz oscillation power is associated with lack of responsiveness during sevoflurane effect-onset and -offset. We also show that anteriorization—the transition from occipitally dominant awake-alpha oscillations to frontally dominant anesthesia induced-alpha oscillations—is not a binary phenomenon. Rather, we suggest that periods, which were defined by lack of responsiveness, represent an intermediate brain state. We conclude that awake-alpha oscillation, previously thought to be

Suppressed Alpha Oscillations Predict Intelligibility of Speech and its Acoustic Details

Science.gov (United States)

Weisz, Nathan

2012-01-01

Modulations of human alpha oscillations (8–13 Hz) accompany many cognitive processes, but their functional role in auditory perception has proven elusive: Do oscillatory dynamics of alpha reflect acoustic details of the speech signal and are they indicative of comprehension success? Acoustically presented words were degraded in acoustic envelope and spectrum in an orthogonal design, and electroencephalogram responses in the frequency domain were analyzed in 24 participants, who rated word comprehensibility after each trial. First, the alpha power suppression during and after a degraded word depended monotonically on spectral and, to a lesser extent, envelope detail. The magnitude of this alpha suppression exhibited an additional and independent influence on later comprehension ratings. Second, source localization of alpha suppression yielded superior parietal, prefrontal, as well as anterior temporal brain areas. Third, multivariate classification of the time–frequency pattern across participants showed that patterns of late posterior alpha power allowed best for above-chance classification of word intelligibility. Results suggest that both magnitude and topography of late alpha suppression in response to single words can indicate a listener's sensitivity to acoustic features and the ability to comprehend speech under adverse listening conditions. PMID:22100354

Introduction of a 20 kHz Nd:YVO4 laser into a hybrid quadrupole time-of-flight mass spectrometer for MALDI-MS imaging.

Science.gov (United States)

Trim, Paul J; Djidja, Marie-Claude; Atkinson, Sally J; Oakes, Keith; Cole, Laura M; Anderson, David M G; Hart, Philippa J; Francese, Simona; Clench, Malcolm R

2010-08-01

A commercial hybrid quadrupole time-of-flight mass spectrometer has been modified for high-speed matrix-assisted laser desorption ionisation (MALDI) imaging using a short-pulse optical technology Nd:YVO(4) laser. The laser operating in frequency-tripled mode (lambda = 355 nm) is capable of delivering 1.5-ns pulses of energy at up to 8 microJ at 5-10 kHz and 3 microJ at 20 kHz. Experiments to improve beam homogeneity and reduce laser speckle by mechanical vibration of the fibre-optic laser delivery system are reported along with data from trial and tissue imaging experiments using the modified instrument. The laser appeared to yield best results for MALDI-MS imaging experiments when operating at repetition rates 5-10 kHz. Combining this with raster imaging allowed images of rat brain sections to be recorded in 37 min. Similarly, images of the distribution of peptides in "on-tissue" digest experiments from tumour tissues were recorded in 1 h and 30 min rather than the 8-h acquisition time previously used. A brief investigation of targeted protein analysis/imaging by multiple reaction monitoring experiments "on-tissue" is reported. A total of 26 transitions were recorded over a 3-s cycle time and images of abundant proteins were successfully recorded.

Posttranscriptional regulation of alpha-amylase II-4 expression by gibberellin in germinating rice seeds.

Science.gov (United States)

Nanjo, Yohei; Asatsuma, Satoru; Itoh, Kimiko; Hori, Hidetaka; Mitsui, Toshiaki; Fujisawa, Yukiko

2004-06-01

Hormonal regulation of expression of alpha-amylase II-4 that lacks the gibberellin-response cis-element (GARE) in the promoter region of the gene was studied in germinating rice (Oryza sativa L.) seeds. Temporal and spatial expression of alpha-amylase II-4 in the aleurone layer were essentially identical to those of alpha-amylase I-1 whose gene contains GARE, although these were distinguishable in the embryo tissues at the early stage of germination. The gibberellin-responsible expression of alpha-amylase II-4 was also similar to that of alpha-amylase I-1. However, the level of alpha-amylase II-4 mRNA was not increased by gibberellin, indicating that the transcriptional enhancement of alpha-amylase II-4 expression did not occur in the aleurone. Gibberellin stimulated the accumulation of 45Ca2+ into the intracellular secretory membrane system. In addition, several inhibitors for Ca2+ signaling, such as EGTA, neomycin, ruthenium red (RuR), and W-7 prevented the gibberellin-induced expression of alpha-amylase II-4 effectively. While the gibberellin-induced expression of alpha-amylase II-4 occurred normally in the aleurone layer of a rice dwarf mutant d1 which is defective in the alpha subunit of the heterotrimeric G protein. Based on these results, it was concluded that the posttranscriptional regulation of alpha-amylase II-4 expression by gibberellin operates in the aleurone layer of germinating rice seed, which is mediated by Ca2+ but not the G protein.

Topographic aspects of photic driving in the electroencephalogram of children and adolescents

Directory of Open Access Journals (Sweden)

Lazarev V.V.

2004-01-01

Full Text Available The electroencephalogram amplitude spectra at 11 fixed frequencies of intermittent photic stimulation of 3 to 24 Hz were combined into driving "profiles" for 14 scalp points in 8 male and 7 female normal subjects aged 9 to 17 years. The driving response varied over frequency and was detected in 70 to 100% of cases in the occipital areas (maximum and in 27 to 77% of cases in the frontal areas (minimum using as a criterion peak amplitude 20% higher than those of the neighbors. Each subject responded, on average, to 9.7 ± 1.15 intermittent photic stimulation frequencies in the right occipital area and to 6.8 ± 1.97 frequencies in the right frontal area. Most of the driving responses (in relation to the previous background were significant according to the spectral F-test (a = 0.05, which also detected changes in some cases of low amplitude responses not revealed by the peak criterion. The profiles had two maxima in the alpha and theta bands in all leads. The latter was not present in the background spectra in the posterior areas and was less pronounced in the anterior ones. The weight of the profile theta maximum increased towards the frontal areas where the two maxima were similar, while the profile amplitudes decreased. The profiles repeated the shape of the background spectra, except for the theta band. The interhemispheric correlation between profiles was high. The theta driving detected in all areas recorded suggests a generalized influence of the theta generators in prepubertal and pubertal subjects.

High-frequency (8 to 16 kHz) reference thresholds and intrasubject threshold variability relative to ototoxicity criteria using a Sennheiser HDA 200 earphone.

Science.gov (United States)

Frank, T

2001-04-01

The first purpose of this study was to determine high-frequency (8 to 16 kHz) thresholds for standardizing reference equivalent threshold sound pressure levels (RETSPLs) for a Sennheiser HDA 200 earphone. The second and perhaps more important purpose of this study was to determine whether repeated high-frequency thresholds using a Sennheiser HDA 200 earphone had a lower intrasubject threshold variability than the ASHA 1994 significant threshold shift criteria for ototoxicity. High-frequency thresholds (8 to 16 kHz) were obtained for 100 (50 male, 50 female) normally hearing (0.25 to 8 kHz) young adults (mean age of 21.2 yr) in four separate test sessions using a Sennheiser HDA 200 earphone. The mean and median high-frequency thresholds were similar for each test session and increased as frequency increased. At each frequency, the high-frequency thresholds were not significantly (p > 0.05) different for gender, test ear, or test session. The median thresholds at each frequency were similar to the 1998 interim ISO RETSPLs; however, large standard deviations and wide threshold distributions indicated very high intersubject threshold variability, especially at 14 and 16 kHz. Threshold repeatability was determined by finding the threshold differences between each possible test session comparison (N = 6). About 98% of all of the threshold differences were within a clinically acceptable range of +/-10 dB from 8 to 14 kHz. The threshold differences between each subject's second, third, and fourth minus their first test session were also found to determine whether intrasubject threshold variability was less than the ASHA 1994 criteria for determining a significant threshold shift due to ototoxicity. The results indicated a false-positive rate of 0% for a threshold shift > or = 20 dB at any frequency and a false-positive rate of 2% for a threshold shift >10 dB at two consecutive frequencies. This study verified that the output of high-frequency audiometers at 0 dB HL using

Modulation of the transient receptor potential vanilloid channel TRPV4 by 4alpha-phorbol esters: a structure-activity study

DEFF Research Database (Denmark)

Klausen, Thomas Kjaer; Pagani, Alberto; Minassi, Alberto

2009-01-01

The mechanism of activation of the transient receptor potential vanilloid 4 (TRPV4) channel by 4alpha-phorbol esters was investigated by combining information from chemical modification of 4alpha-phorbol-didecanoate (4alpha-PDD, 2a), site-directed mutagenesis, Ca(2+) imaging, and electrophysiology....... Binding of 4alpha-phorbol esters occurs in a loop in the TM3-TM4 domain of TRPV4 that is analogous to the capsaicin binding site of TRPV1, and the ester decoration of ring C and the A,B ring junction are critical for activity. The lipophilic ester groups on ring C serve mainly as a steering element...

Is theta burst stimulation applied to visual cortex able to modulate peripheral visual acuity?

Directory of Open Access Journals (Sweden)

Sabrina Brückner

Full Text Available Repetitive transcranial magnetic stimulation is usually applied to visual cortex to explore the effects on cortical excitability. Most researchers therefore concentrate on changes of phosphene threshold, rarely on consequences for visual performance. Thus, we investigated peripheral visual acuity in the four quadrants of the visual field using Landolt C optotypes before and after repetitive stimulation of the visual cortex. We applied continuous and intermittend theta burst stimulation with various stimulation intensities (60%, 80%, 100%, 120% of individual phosphene threshold as well as monophasic and biphasic 1 Hz stimulation, respectively. As an important result, no serious adverse effects were observed. In particular, no seizure was induced, even with theta burst stimulation applied with 120% of individual phosphene threshold. In only one case stimulation was ceased because the subject reported intolerable pain. Baseline visual acuity decreased over sessions, indicating a continuous training effect. Unexpectedly, none of the applied transcranial magnetic stimulation protocols had an effect on performance: no change in visual acuity was found in any of the four quadrants of the visual field. Binocular viewing as well as the use of peripheral instead of foveal presentation of the stimuli might have contributed to this result. Furthermore, intraindividual variability could have masked the TMS- induced effects on visual acuity.

EEG differences between the opioid and adrenergic psyhoneuroendocrine rat types

DEFF Research Database (Denmark)

Cristea, A; Moldovan, M; Munteanu, A M

2000-01-01

(BEA) of the "O" and "A" rat types during restrained wakefulness and anesthesia with Ether and chloral hydrate (CHL). The differentiation of the psyhoneuroendocrine rat types was made using the level of painful sensitivity. 13 hypersensitive "A" and 14 hyposensitive "O" rats were selected from a 91......% (SEF95) and the relative spectral power (RSP) within the Theta (4.5-7.5 Hz), Alpha (7.5-12 Hz) and Beta (12.5-30 Hz) bands. The quantification method used was able to detect statistically significant differences between the two psyhoneuroendocrine rat types during consciousness and light ether...... anesthesia but failed to show any differences during the deep CHL anesthesia. The particularities were shown to be topographically related with the fronto-parietal regions were "O" type showed a higher SEF95 during the awake restrained state. The pain sensitive "A" type showed a significant intrahemispheric...

The tumor necrosis factor-alpha-induced protein 8 family in immune homeostasis and inflammatory cancer diseases.

Science.gov (United States)

Luan, Y Y; Yao, Y M; Sheng, Z Y

2013-01-01

Within the immune system homeostasis is maintained by a myriad of mechanisms that include the regulation of immune cell activation and programmed cell death. The breakdown of immune homeostasis may lead to fatal inflammatory diseases. We set out to identify genes of tumor necrosis factor-alpha-induced protein 8 (TNFAIP8) family that has a functional role in the process of immune homeostasis. Tumor necrosis factor-alpha-induced protein 8 (TNFAIP8), which functions as an oncogenic molecule, is also associated with enhanced cell survival and inhibition of apoptosis. Tumor necrosis factor-alpha-induced protein 8-like 2 (TIPE2) governs immune homeostasis in both the innate and adaptive immune system and prevents hyper-responsiveness by negatively regulating signaling via T cell receptors and Toll-like receptors (TLRs). There also exist two highly homologous but uncharacterized proteins, TIPE1 and TIPE3. This review is an attempt to provide a summary of TNFAIP8 family associated with immune homeostasis and inflammatory cancer diseases.

15 beta-hydroxysteroids (Part IV). Steroids of the human perinatal period: the synthesis of 3 alpha,15 beta,17 alpha-trihydroxy-5 alpha-pregnan-20-one and its A/B-ring configurational isomers.

Science.gov (United States)

Reeder, A Y; Joannou, G E

1995-12-01

In recent years several 15 beta-hydroxysteroids have emerged pathognomonic of adrenal disorders in human neonates of which 3 alpha,15 beta,17 alpha-trihydroxy-5 beta-pregnan-20-one (2) was the first to be identified in the urine of newborn infants affected with congenital adrenal hyperplasia. In this investigation we report the synthesis of the three remaining 3 xi,5 xi-isomers, namely 3 alpha,15 beta,17 alpha-trihydroxy-5 alpha-pregnan-20-one (3), 3 beta,15 beta,17 alpha-trihydroxy-5 alpha-pregnan-20-one (7) and 3 beta,15 beta,17 alpha-trihydroxy-5 beta-pregnan-20-one (8) for their definitive identification in pathological conditions in human neonates. 3 beta,15 beta-Diacetoxy-17 alpha-hydroxy-5-pregnen-20-one (11), a product of chemical synthesis was converted to the isomeric 3 and 7, while conversion of 15 beta,17 alpha-dihydroxy-4-pregnen-3,20-dione (4), a product of microbiological transformation, resulted in the preparation of 8. In brief, selective acetate hydrolysis of 11 gave 15 beta-acetoxy-3 beta,17 alpha-dihydroxy-5-pregnen-20-one (12) which on catalytic hydrogenation gave 15 beta-acetoxy-3 beta,17 alpha-dihydroxy-5 alpha-pregnan-20-one (13) a common intermediate for the synthesis of the 3 beta(and alpha),5 alpha-isomers. Hydrolysis of the 15 beta-acetate gave 7, whereas oxidation with pyridinium chlorochromate gave 15 beta-acetoxy-17 alpha-hydroxy-5 alpha-pregnan-3,20-dione (14) which on reduction with L-Selectride and hydrolysis of the 15 beta-acetate gave 3. Finally, hydrogenation of 4 gave 15 beta, 17 alpha-dihydroxy-5 beta-pregnan-3,20-dione (10) which on reduction with L-Selectride gave 8.

Hippocampal theta activity in the acute cerveau isolé cat.

Science.gov (United States)

Gottesmann, C; Zernicki, B; Gandolfo, G

1981-01-01

In three cerveau isole cats, cortical and hippocampal EEG activity were recorded. In the cortical records, spindles alternated with low-voltage activity, whereas theta activity dominated in the hippocampus. The amount and frequency of theta were similar to those described previously for the pretrigeminal cat. In confirmation of previous results on rats, although cortical EEG activity differs in cerveau isole cat and pretrigeminal cat, both preparations show domination of theta activity in the hippocampus. It is concluded that the mesencephalic transection eliminates inhibitory effects from the lower brainstem on generators of the theta rhythm.

Heat capacity of solid parahydrogen

Energy Technology Data Exchange (ETDEWEB)

Bagatskij, M I; Minchina, I Ya; Manzhelij, V G [AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur

1984-10-01

A vacuum adiabatic calorimeter has been developed to investigate cryocrystals and their solutions in the range 0.4-300 K. Heat capacity of hydrogen with the orthomodification concentration 5 x 10/sup -3/ at.% between 0.5 and 8 K has been investigated. The limiting Debye temperature at T ..-->.. 0 has been obtained: (THETA/sub 0/=118.5 +- 0.5 K). It has been shown that heat capacity of solid parahydrogen, as that of other cryocrystals with the central interaction and closely packed lattices (/sup 4/He, Ne, Ar, Kr, Xe), low temperatures is given by the universal relation proposed by Barron and Morrison Csub(V) AT/sup 3/(1+..cap alpha../sub 1/(T/THETA/sub 0/)/sup 2/ + ..cap alpha../sub 2/(T/THETA/sub 0/)/sup 4/ ...). The effect of the sample time prehistory on the experimental heat capacity values of hydrogen with g.21 at.% orthomodification has been studied, and the times during which configurational equilibration in this solution is reached have been estimated.

Spontaneous local alpha oscillations predict motion-induced blindness.

Science.gov (United States)

Händel, Barbara F; Jensen, Ole

2014-11-01

Bistable visual illusions are well suited for exploring the neuronal states of the brain underlying changes in perception. In this study, we investigated oscillatory activity associated with 'motion-induced blindness' (MIB), which denotes the perceptual disappearance of salient target stimuli when a moving pattern is superimposed on them (Bonneh et al., ). We applied an MIB paradigm in which illusory target disappearances would occur independently in the left and right hemifields. Both illusory and real target disappearance were followed by an alpha lateralization with weaker contralateral than ipsilateral alpha activity (~10 Hz). However, only the illusion showed early alpha lateralization in the opposite direction, which preceded the alpha effect present for both conditions and coincided with the estimated onset of the illusion. The duration of the illusory disappearance was further predicted by the magnitude of this early lateralization when considered over subjects. In the gamma band (60-80 Hz), we found an increase in activity contralateral relative to ipsilateral only after a real disappearance. Whereas early alpha activity was predictive of onset and length of the illusory percept, gamma activity showed no modulation in relation to the illusion. Our study demonstrates that the spontaneous changes in visual alpha activity have perceptual consequences. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Human cortical EEG rhythms during long-term episodic memory task. A high-resolution EEG study of the HERA model.

Science.gov (United States)

Babiloni, Claudio; Babiloni, Fabio; Carducci, Filippo; Cappa, Stefano; Cincotti, Febo; Del Percio, Claudio; Miniussi, Carlo; Moretti, Davide Vito; Pasqualetti, Patrizio; Rossi, Simone; Sosta, Katiuscia; Rossini, Paolo Maria

2004-04-01

Many recent neuroimaging studies of episodic memory have indicated an asymmetry in prefrontal involvement, with the left prefrontal cortex more involved than the right in encoding, the right more than the left in retrieval (hemispheric encoding and retrieval asymmetry, or HERA model). In this electroencephalographic (EEG) high-resolution study, we studied brain rhythmicity during a visual episodic memory (recognition) task. The theta (4-6 Hz), alpha (6-12 Hz) and gamma (28-48 Hz) oscillations were investigated during a visuospatial long-term episodic memory task including an encoding (ENC) and retrieval (RET) phases. During the ENC phase, 25 figures representing interiors of buildings ("indoor") were randomly intermingled with 25 figures representing landscapes ("landscapes"). Subject's response was given at left ("indoor") or right ("landscapes") mouse button. During the RET phase (1 h later), 25 figures representing previously presented "indoor" pictures ("tests") were randomly intermingled with 25 figures representing novel "indoor" ("distractors"). Again, a mouse response was required. Theta and alpha EEG results showed no change of frontal rhythmicity. In contrast, the HERA prediction of asymmetry was fitted only by EEG gamma responses, but only in the posterior parietal areas. The ENC phase was associated with gamma EEG oscillations over left parietal cortex. Afterward, the RET phase was associated with gamma EEG oscillations predominantly over right parietal cortex. The predicted HERA asymmetry was thus observed in an unexpected location. This discrepancy may be due to the differential sensitivity of neuroimaging methods to selected components of cognitive processing. The strict relation between gamma response and perception suggests that retrieval processes of long-term memory deeply impinged upon sensory representation of the stored material.

Targeted Alpha Therapy: From Alpha to Omega

International Nuclear Information System (INIS)

Allen, Barry J; Clarke, Raymond; Huang Chenyu

2013-01-01

This review covers the broad spectrum of Targeted Alpha Therapy (TAT) research in Australia; from in vitro and in vivo studies to clinical trials. The principle of tumour anti-vascular alpha therapy (TAVAT) is discussed in terms of its validation by Monte Carlo calculations of vascular models and the potential role of biological dosimetry is examined. Summmary of this review is as follows: 1. The essence of TAT 2. Therapeutic objectives 3. TAVAT and Monte Carlo microdosimetry 4. Biological dosimetry 5. Preclinical studies 6. Clinical trials 7. What next? 8. Obstacles. (author)

A pedagogical introduction to theta functions

International Nuclear Information System (INIS)

Koh, I.G.; Shin, H.J.

1988-01-01

This paper reports on revolutions in physics that have been frequently accompanied by new developments in mathematics. In seventeenth century, Newton has initiated a program of describing celestial motion by classical mechanics. Integral and differential calculus was essential tool. Orbits of the moon and the earth are given by solving the differential equation of Newton's equation. Imagine a situation where one tries to solve such orbits without integral and differential calculus. Similar revolutions in understanding quantum gravity and in making deep connections between statistical and string physics are under progresses. One of indispensible tools are the theory of theta functions on Riemann surfaces. Since the literature of theta functions is mainly written by professional mathematician, physicists feel somewhat uneasy to begin to read a long chapters of lemmas and theorems, but it is now generally accepted that theta function is essential in understanding two-dimensional conformal field theory as the integral and differential calculus was indispensible in Newtonian mechanics

Antagonizing the alpha(4)beta(1) Integrin, but Not alpha(4)beta(7), Inhibits Leukocytic Infiltration of the Central Nervous System in Rhesus Monkey Experimental Autoimmune Encephalomyelitis

NARCIS (Netherlands)

Haanstra, Krista G.; Hofman, Sam O.; Estevao, Dave M. Lopes; Blezer, Erwin L. A.; Bauer, Jan; Yang, Li-Li; Wyant, Tim; Csizmadia, Vilmos; 't Hart, Bert A.; Fedyk, Eric R.

2013-01-01

The immune system is characterized by the preferential migration of lymphocytes through specific tissues (i.e., tissue tropism). Tissue tropism is mediated, in part, by the alpha(4) integrins expressed by T lymphocytes. The alpha(4)beta(1) integrin mediates migration of memory T lymphocytes into the

The alpha3 laminin subunit, alpha6beta4 and alpha3beta1 integrin coordinately regulate wound healing in cultured epithelial cells and in the skin

DEFF Research Database (Denmark)

Goldfinger, L E; Hopkinson, S B; deHart, G W

1999-01-01

Previously, we demonstrated that proteolytic processing within the globular domain of the alpha3 subunit of laminin-5 (LN5) converts LN5 from a cell motility-inducing factor to a protein complex that can trigger the formation of hemidesmosomes, certain cell-matrix attachment sites found in epithe......-inhibiting antibodies, we provide evidence that LN5 and its two integrin receptors (alpha6beta4 and alpha3beta1) appear necessary for wound healing to occur in MCF-10A cell culture wounds. We propose a model for healing of wounded epithelial tissues based on these results....... in epithelial cells. We have prepared a monoclonal antibody (12C4) whose epitope is located toward the carboxy terminus of the globular domain of the alpha3 laminin subunit. This epitope is lost from the alpha3 subunit as a consequence of proteolytic processing. Antibody 12C4 stains throughout the matrix...... the wound site. A similar phenomenon is observed in human skin wounds, since we also detect expression of the unprocessed alpha3 laminin subunit at the leading tip of the sheet of epidermal cells that epithelializes skin wounds in vivo. In addition, using alpha3 laminin subunit and integrin function...

The importance of ignoring: Alpha oscillations protect selectivity.

Science.gov (United States)

Payne, Lisa; Sekuler, Robert

2014-06-01

Selective attention is often thought to entail an enhancement of some task-relevant stimulus or attribute. We discuss the perspective that ignoring irrelevant, distracting information plays a complementary role in information processing. Cortical oscillations within the alpha (8-14 Hz) frequency band have emerged as a marker of sensory suppression. This suppression is linked to selective attention for visual, auditory, somatic, and verbal stimuli. Inhibiting processing of irrelevant input makes responses more accurate and timely. It also helps protect material held in short-term memory against disruption. Furthermore, this selective process keeps irrelevant information from distorting the fidelity of memories. Memory is only as good as the perceptual representations on which it is based, and on whose maintenance it depends. Modulation of alpha oscillations can be exploited as an active, purposeful mechanism to help people pay attention and remember the things that matter.

The tree-alpha Faddeev calculation on 12C bound states with a Pauli correct alpha-alpha potential

International Nuclear Information System (INIS)

Kamada, Hiroyuki; Oryu, Shinsho

1986-01-01

The three-alpha model of 12 C is investigated by the Faddeev formalism with the UIM alpha-alpha potential, in which the Pauli effect between two-alpha system was taken into account adequately. The potential can reproduce the on- and off-shell effects of the alpha-alpha interaction by the rank-4 separable type for the S-wave, the rank-3 one for the D-wave, and the rank-2 one for the G-wave, in which two of the ranks in the S-wave, and one in the D-wave are prepared to eliminate the Pauli forbidden states. We obtained three even states J π = 0 + , 2 + , 4 + , and two odd states 1 - , 3 - , below the alpha- 8 Be(0 + g.s) threshold energy. The even parity states gain larger binding energies than those which have been obtained by former Faddeev calculation with the rank-1 Kukulin and Neudatchin (KN) potential. On the other hand, for the odd parity states, we obtained smaller binding energies than the former one. It is found that our Faddeev calculation with the UIM potential does not miss any important low-lying levels of 12 C, in which any spurious states do not appear. (author)

[Electroencephalographic characteristic of cognitive-specific alerting attention in verbal learning--III: Localized characteristics of EEG spatial synchronization].

Science.gov (United States)

Dan'ko, S G; Kachalova, L M; Solov'eva, M L

2010-01-01

Electroencephalograms (EEG) were recorder in 19 standard derivations in 88 healthy subjects, while they were in the states: rest with eyes open; memorization (learning) of verbal bilingual semantic pairs (Latin and Russian languages); the retrieval of the rote information from memory (control). We compared estimates of EEG coherence in these states for the frequency bands theta (4-7 Hz), alpha-1 (7-10 Hz), alpha-2 (10-13 Hz), beta-1 (13-18 Hz), beta-2 (18-30 Hz), gamma (30-40 Hz). When compared with the rest most strongly expressed: for memorization a decrease of coherence in the pairs of derivations from frontal and central areas of the cortex in the EEG frequency bands; for retrieval an increase of coherence in interhemispheric derivation pairs of pariental-occipital region in majority of the frequency bands. For the retrieval also increases of coherence in the beta2 and gamma bands, along with coherence decreases at low frequencies take place in pairs formed by derivations from the parieto-occipital region with derivations from the frontal and the central ones. Dynamics of EEG coherence in comparisons of memorization and retrieval from the rest and each are expressed significantly more in the interhemispheric and crosshemispheric pairs of derivations than in the intrahemispheric pairs. Revealed topographic specificity of the dynamics of EEG coherence by changing the states is considered in terms of ideas about cognitive-specific forms of sustained goal-directed mental attention.

Movement-related theta rhythm in humans: coordinating self-directed hippocampal learning.

Directory of Open Access Journals (Sweden)

Raphael Kaplan

Full Text Available The hippocampus is crucial for episodic or declarative memory and the theta rhythm has been implicated in mnemonic processing, but the functional contribution of theta to memory remains the subject of intense speculation. Recent evidence suggests that the hippocampus might function as a network hub for volitional learning. In contrast to human experiments, electrophysiological recordings in the hippocampus of behaving rodents are dominated by theta oscillations reflecting volitional movement, which has been linked to spatial exploration and encoding. This literature makes the surprising cross-species prediction that the human hippocampal theta rhythm supports memory by coordinating exploratory movements in the service of self-directed learning. We examined the links between theta, spatial exploration, and memory encoding by designing an interactive human spatial navigation paradigm combined with multimodal neuroimaging. We used both non-invasive whole-head Magnetoencephalography (MEG to look at theta oscillations and Functional Magnetic Resonance Imaging (fMRI to look at brain regions associated with volitional movement and learning. We found that theta power increases during the self-initiation of virtual movement, additionally correlating with subsequent memory performance and environmental familiarity. Performance-related hippocampal theta increases were observed during a static pre-navigation retrieval phase, where planning for subsequent navigation occurred. Furthermore, periods of the task showing movement-related theta increases showed decreased fMRI activity in the parahippocampus and increased activity in the hippocampus and other brain regions that strikingly overlap with the previously observed volitional learning network (the reverse pattern was seen for stationary periods. These fMRI changes also correlated with participant's performance. Our findings suggest that the human hippocampal theta rhythm supports memory by coordinating

Enthalpies of combustion and formation of {alpha}-D-glucoheptono-1,4-lactone and {alpha},{beta}-glucooctanoic-1,4-lactone

Energy Technology Data Exchange (ETDEWEB)

Amador, Patricia [Facultad de Ciencias Qui' micas, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, Col. Manuel, C.P. 72570 Puebla Pue (Mexico)], E-mail: cs000721@siu.buap.mx; Mata, Marian Y.; Flores, Henoc [Facultad de Ciencias Qui' micas, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, Col. Manuel, C.P. 72570 Puebla Pue (Mexico)

2008-05-15

The standard molar energies of combustion, {delta}{sub c}U{sub m}{sup 0}(cr,298.15K), of {alpha}-D-glucoheptono-1,4-lactone (GH) and {alpha},{beta}-glucooctanoic-1,4-lactone (GO) were obtained by micro-combustion calorimetry. The obtained values are -(2924.6 {+-} 2.3) kJ . mol{sup -1} and -(3459.5 {+-} 2.5) kJ . mol{sup -1}, respectively. From combustion energies, the standard molar enthalpies of formation in crystalline phase, {delta}{sub f}H{sub m}{sup 0}(cr,298.15K), for GH and GO were determined as -(1546.2 {+-} 2.5) kJ . mol{sup -1} and -(1690.6 {+-} 2.7) kJ . mol{sup -1}, respectively. Also it was found that when the hydroxyl group number increases in the aldonolactones their standard molar enthalpies of formation increase too.

Effects of the India–Pakistan border earthquake on the atmospherics at 6 kHz and 9 kHz recorded at Tripura

Directory of Open Access Journals (Sweden)

Sudarsan Barui

2011-04-01

Full Text Available The unusual variations observed in the records of the integrated field intensity of the atmospherics (IFIA at 6 kHz and 9 kHz at Agartala, Tripura, in the north-eastern state of India (latitude, 23˚ N; longitude, 91.4˚ E during the large earthquake on October 8, 2005 at Muzaffarabad (latitude, 34.53˚ N; longitude, 73.58˚ E in Kashmir in Pakistan are here analyzed. Spiky variations in the IFIA at 6 kHz and 9 kHz were observed several days previous to the day of the earthquake (from midnight, September 28, 2005. The effects persisted for some days, decayed gradually, and eventually ceased on October 31, 2005. The spikes are distinctly superimposed on the ambient level

A GH57 4-alpha-glucanotransferase of hyperthermophilic origin with potential for alkyl glycoside production

NARCIS (Netherlands)

Paul, Catherine J.; Leemhuis, Hans; Dobruchowska, Justyna M.; Grey, Carl; Onnby, Linda; van Leeuwen, Sander S.; Dijkhuizen, Lubbert; Karlsson, Eva Nordberg

4-alpha-Glucanotransferase (GTase) enzymes (EC 2.4.1.25) modulate the size of alpha-glucans by cleaving and reforming alpha-1,4 glycosidic bonds in alpha-glucans, an essential process in starch and glycogen metabolism in plants and microorganisms. The glycoside hydrolase family 57 enzyme (GTase57)