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Results for “Brain waves”

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At least 307 records · Page 17Linked to original sources

PubMed2006

[Relaxation induced by photic stimulation in tinnitus patients].

The therapeutic effect of applying photic stimulation was evaluated in a sample of 17 patients with chronic tinnitus. The employed optical stimulation technique triggers the activity of brain waves and induces deep relaxation characterized by increased EEG activity in the theta and delta spectrum. The expected therapeutic effect beyond relaxation was a decrease in subjective tinnitus distress and further improvements in well-being. All patients received ten applications of photic stimulation, each lasting 30 min. Every application markedly increased the peripheral blood circulation, thus indicating a relaxation effect. The emotional and cognitive impairments as well as the subjective tinnitus distress significantly decreased during treatment while sleep disturbances showed a tendency towards improvement. Overall, tinnitus distress markedly decreased and general well-being improved. The photic stimulation technique is proposed as a relief for tinnitus patients who do not respond to conventional relaxation techniques.

Adult↗

PubMed2006

Hippocampal glutamate concentration predicts cerebral theta oscillations during cognitive processing.

RATIONALE: Brain waves reflect collective behavior of neurons and provide insight into distributed network processing. Frontal and hippocampal theta oscillations (4-7 Hz) were linked to cognitive tasks and animal studies have suggested an involvement of glutamatergic neurotransmission in integrative frontal-hippocampal processing. Human evidence for such relationships is lacking. METHODS: Here, we studied the associations between glutamate concentrations in the hippocampal region, measured by a 3-T proton magnetic resonance spectroscopy (1H-MRS), and EEG theta activity during an auditory target detection paradigm. RESULTS: A robust relationship between hippocampal glutamate and frontal theta activity during stimulus processing was found. Moreover, frontal theta oscillations were related to response speed. CONCLUSION: The results suggest a functional coupling between the frontal cortex and hippocampal region during stimulus processing and support the idea of the hippocampus as a neural rhythm generator driven by glutamatergic neurotransmission. These preliminary data show, for the first time, a relationship between in vivo measured glutamate and basic cerebral information processing in humans.

Adult↗

PubMed1980

Electrocardiographic changes in cerebrovascular hemorrhage.

The electrocardiographic abnormalities found in localized cerebrovascular hemorrhage which have been documented by computerized tomography (CT) scans are described. Frontal lobe hemorrhages are associated especially with the electrocardiographic abnormalities of QT prolongation and neurogenic T waves. Brain stem hemorrhage seems to be associated with noncardiogenic pulmonary edema, and sudden development of atrial fibrillation. It is proposed that the cause of ECG abnormalities in association with lesions in the vicinity of area 13 on the orbital surface of the frontal lobe, or around the circle of Willis, results from alterations in sympathetic and parasympathetic tone mediated by fibers from the orbito-frontal area to the heart via the stellate ganglia.

Adolescent↗

PubMed1993

P300 component of the event-related potentials (ERP) during an attention task: effects of age, stimulus modality and event probability.

The effects of age, stimulus modality and event probability on event-related potentials (ERP) were studied in 12 young and 12 elderly healthy subjects. The ERP were recorded from 15 electrodes referred to linked ears. Results showed that both amplitude and latency of the P300 component are affected by aging. Study of the latency of the earlier ERP components in the two age groups revealed that the P300 delay was not imputable to a delay of the earlier components. P300 amplitude and latency were also affected by event probability and stimulus modality: infrequent stimulus involved higher and later P300, but this effect was more pronounced in the young than in the old group; higher and later P300 were also recorded during the visual task compared to the auditory. Topographical repartition of the brain wave revealed a predominance of the central sites (Fz, Cz, Pz). The findings are discussed in relation to the sensitivity of the ERP assessment procedures in age related modifications of information processing.

Acoustic Stimulation↗

PubMed1979

Successful and unsuccessful university students: quantitative hemispheric EEG differences.

Quantitative measurements of EEG amplitudes were obtained on academically successful and unsuccessful university students during a 5 min, eyes closed, relaxed state. Integrations measured continuously the fully rectified amplitudes of brain waves cumulated over successive epochs of 5 s, regardless of the correlation of a wave to a particular frequency band. The poor academic students, as a group, displayed a significantly higher right/left variance ratio of the cumulated amplitudes at both the temporal and occipital sites than the academically successful group. Upon examining the histograms for these cumulated amplitudes, it was found that the unsuccessful students displayed a greater number of polymodal (non-Gaussian) distributions, particularly in the right hemisphere. These data, which resemble patterns often found in depression, suggest a relative disorganization of right hemispheric activity in the unsuccessful students, and within limits, seems related to the cognitive and/or emotional stability of these students.

Achievement↗

PubMed1991

Melatonin supplementation from early morning auto-urine drinking.

Drinking one's morning urine ('amaroli') is a traditional practice of the yogic religion still widely performed. The pineal hormone melatonin and its conjugated esters are present in morning urine in significant quantities. Drinking the first morning urine restores plasma night-time melatonin levels due to deconjugation of its esters to melatonin. Exogenous melatonin, by either regulation of the sleep-wake cycle or enhancement of the physiological prerequisites for mediation (decreased body awareness (i.e. analgesia) and claimed slowed brain wave activity and heightened visualization ability) may be the mechanism behind the alleged benefits of 'amaroli'.

Humans↗

PubMed2005

Psychophysiological evidence that the SNARC effect has its functional locus in a response selection stage.

When participants judge the parity of visually presented digits, left-hand responses are faster for numerically small numbers, whereas right-hand responses are faster for large numbers. The present study aimed to find more direct evidence for the functional locus of this effect by recording brain waves while participants performed speeded parity judgments giving manual responses. Our results show clear and robust SNARC effects in the response-locked event-related potentials (ERPs) compared to the stimulus-locked ERPs, confirming that the SNARC effect arises during response-related rather than stimulus-related processing stages. Further analyses of lateralized readiness potentials strongly suggest that the SNARC effect begins to emerge in a response-related stage prior to response preparation and execution, more specifically, in a response selection stage.

Adolescent↗

PubMed2005

Neural correlates of perceptual contributions to nondeclarative memory for faces.

Face priming is a nondeclarative memory phenomenon that can be observed when recognition is facilitated for a recently encountered face. This data-driven form of priming is distinct from conceptually driven priming. Moreover, it includes two dissociable components, the facilitated access to pre-existing representations and facilitation in perceptual processing of faces. In the present study, we measured neural correlates of perceptual contributions to face priming with event-related brain potentials. Faces appeared two times (separated by 7-17 s), while participants discriminated familiar from unfamiliar faces. Half of the initial face stimuli were inverted, thereby disrupting perceptual face processing and making possible an assessment of perceptual contributions to face priming. Whereas none of the brain waves previously linked to perceptual processing of faces showed indications of priming, such effects were observed between 200 and 600 ms at left occipito-parieto-temporal recording sites. This electrical activity was present for both unfamiliar and familiar faces. The scalp topography of this effect was consistent with sources within the temporal and occipital cortices of the left hemisphere (based on a LORETA source localization). These findings suggest that priming of perceptual face processing is subserved by prolonged neural activity from 200 to 600 ms primarily in the left hemisphere. We propose that this priming reflects facilitated selection based on second-order relations among facial features.

Adolescent↗

PubMed2003

Auditory sensory processing in autism: a magnetoencephalographic study.

BACKGROUND: Patients with autism show clinical features suggestive of abnormal processing of auditory and other sensory information. We hypothesized that low-functioning autistic subjects present abnormalities in discriminating simple auditory stimuli at sensory system preconscious stages of cortical processing. METHODS: To verify our hypothesis, we used magnetoencephalographic measurements of mismatch field (MMF), which reflects the detection of a change in the physical characteristics of a repetitive sound. Fourteen patients (aged 8-32 years) who met DSM-IV diagnostic criteria for autistic disorder participated in an auditory oddball experiment. Ten healthy participants matched for age and gender acted as control subjects. RESULTS: Significant differences in cerebral responses between patients and control subjects were recorded. Whereas control subjects showed a clearly identifiable MMF, with distinct generators in the M100 brain wave with regard to latency, position, and strength, no identifiable MMF was present in the autistic group. CONCLUSIONS: Our findings suggest that low-functioning autistic subjects present a dysfunction at preconscious stages of cortical auditory discrimination, playing a role in the abnormal processing of auditory sensory afferences. The attention independence of the MMF allows for exclusion of an effect related to impaired attention or task-related responses.

Acoustic Stimulation↗

PubMed1998

Effects of tobacco smoking and abstinence on middle latency auditory evoked potentials.

OBJECTIVE: To evaluate the effects of tobacco cigarette smoking and overnight abstinence on middle latency auditory evoked potentials among smokers and nonsmokers. METHODS: Groups of 9 to 10 adult male and female nonsmokers and smokers participated in the study. Each person volunteered for two laboratory sessions conducted in the early afternoon on 2 separate days. Smokers abstained from tobacco products 6 to 15 hours before the abstinent session and maintained their usual smoking behavior before the smoking session. The nonsmokers had a similar laboratory experience but sham smoked by means of inhaling air. Middle latency auditory evoked potentials were recorded from Cz to both ears as reference. RESULT: The latencies of the Na and Pa potentials during the smoking session were significantly (p < 0.01) shorter than those in abstinent smokers and nonsmokers. After smoking, peak-to-trough amplitudes for the V-Na, Na-Pa, and Pa-Nb potentials were larger than those after abstinence and significantly larger than those among nonsmokers. CONCLUSIONS: The shorter latencies of the middle latency brain wave components in the smoking session suggest faster processing of sensory information after cigarette smoking. Larger Pa amplitudes after cigarette smoking suggest a higher arousal level than that among partially abstinent smokers and nonsmokers.

Adult↗

PubMed1977

Neonatal seizures associated with narcotic withdrawal.

Among 302 neonates passively addicted to narcotics, 18 had seizures that were attributed to withdrawal. Of those 18 infants, 10 were among the 127 infants exposed to methadone (7.8%), whereas only one of them was among the 83 infants exposed to heroin (1.2%). Generalized motor seizures and myoclonic jerks were the predominant convulsive manifestations. Paregoric was more effective than was diazepam in controlling and preventing these seizures once they occurred. Electroencephalograms were obtained on 13 neonates in the interictal period; 12 of these ECGs were normal. Three infants, two with myoclonic jerks, had paroxysmal brain wave activity at the time of the seizures.

Diazepam↗

PubMed2001

A psychophysiological analysis of inhibitory motor control in the stop-signal paradigm.

We examined two potential inhibitory mechanisms for stopping a motor response. Participants performed a standard visual two-choice task in which visual stop signals and no-go signals were presented on a small proportion of the trials. Psychophysiological measures were taken during task performance to examine the time course of response activation and inhibition. The results were consistent with a horse race model previously proposed to account for data obtained using a stop-signal paradigm. The pattern of psychophysiological responses was similar on stop-signal and no-go trials suggesting that the same mechanism may initiate inhibitory control in both situations. We found a distinct frontal brain wave suggesting that inhibitory motor control is instigated from the frontal cortex. The results are best explained in terms of a single, centrally located inhibition mechanism. Results are discussed in terms of current neurophysiological knowledge.

Adult↗

PubMed2000

Effects of body-mind training and relaxation stretching on persons with chronic toxic encephalopathy.

The purpose of this project was to investigate the psychological and physical effects of training of body awareness and slow stretching on persons with chronic toxic encephalopathy (CTE). In the present study, a method of self-regulation, a body-mind training, is presented. The body-mind training used was a guided relaxation technique combined with meditative stretching. The techniques are introduced and the psychological and physiological effects of the training is presented. Eight subjects with CTE, 48.5 years, were trained for 8 weeks. Outcome measures were percentage alpha brain waves (alpha%), electromyography (EMG) on the frontalis muscle, state-trait anxiety (STAI), creativity (RAT), and mood measured as anxiousness, humour and mental fatigue. The mean alpha% increased 52% during the training period (P < 0.01), and the EMG decreased 31% (P < 0.001. State anxiety decreased 22% during the training period (P < 0.01), but no changes were observed in trait anxiety and in the creativity score. The level of anxiousness and fatigue before a training session decreased during the training period. In conclusion, the body-mind training resulted in an improved ability for physical and mental relaxation as indicated from the lower EMG, the higher alpha% and the decrease in state anxiety.

Alpha Rhythm↗

PubMed1997

Consciousness in a Self-Learning, Memory-Controlled, Compound Machine.

A memory-controlled, sensor/actuator machine senses conditions in its environment at given moments, and attempts to produce an action based upon its memory. However, a sensor/actuator machine will stop producing new behavior if its environment is removed. A sensor/sensor unit can be added to the sensor/actuator machine, forming a compound machine. The sensor/sensor unit produces a stream of internally created sensed conditions, which can replace the sensed conditions from the environment. This illusion of an environment is similar to consciousness. In addition, actuator/sensor and actuator/actuator units can be added to this compound machine to further enhance its ability to function without an environment. Predetermined and empirical memory cells can be distributed throughout the control units of this compound machine to provide instinctive and learned behavior. The internal and exterior behavior of this compound machine can be modified greatly by changing the cycle start and ramp signals that activate these different kinds of memory cells. These signals are similar in form to brain waves.

Journal Article↗

PubMed1998

Mining multi-channel EEG for its information content: an ANN-based method for a brain-computer interface.

We have studied 56-channel electroencephalograms (EEG) from three subjects who planned and performed three kinds of movements, left and right index finger, and right foot movement. Using autoregressive modeling of EEG time series and artificial neural nets (ANN), we have developed a classifier that can tell which movement is performed from a segment of the EEG signal from a single trial. The classifier's rate of recognition of EEGs not seen before was 92-99% on the basis of a 1s segment per trial. The recognition rate provides a pragmatic measure of the information content of the EEG signal. This high recognition rate makes the classifier suitable for a so-called 'Brain-Computer Interface', a system that allows one to control a computer, or another device, with ones brain waves. Our classifier Laplace filters the EEG spatially, but makes use of its entire frequency range, and automatically locates regions of relevant activity on the skull.

Journal Article↗

PubMed1998

Behavioral and electrophysiological effects of task-irrelevant sound change: a new distraction paradigm.

A distraction paradigm was utilized that is suited to yield reliable auditory distraction on an individual level even with rather small frequency deviances (7%). Distraction to these tiny deviants was achieved by embedding task-relevant aspects and task-irrelevant, distracting aspects of stimulation into the same perceptual object. Event-related potential (ERP) and behavioral effects of this newly developed paradigm were determined. Subjects received tones that could be of short or long duration equiprobably. They were instructed to press a response button to long-duration tones (targets). In oddball blocks, tones could be of standard frequency or of low-probability (p=0.1), deviant frequency. The task-irrelevant frequency deviants elicited MMN, N2b, and P3a components, and caused impoverished behavioral performance to targets. The usage of tiny distractors permits an interpretation of auditory distraction in terms of attention switching due to a particular memory-related change-detection process. On the basis of the results from an additional condition in which tones were of 10 different frequencies (involving those frequencies which served as standard and deviant in oddball blocks), it is argued that one important prerequisite for linking the neural mechanisms reflected in change-related brain waves to behavioral distraction effects may be regarded as fulfilled. The robustness of the distraction effects to tiny deviations was confirmed in two control experiments.

Acoustic Stimulation↗

PubMed1998

Modulation of serum testosterone and autonomic function through stimulation of the male human vomeronasal organ (VNO) with pregna-4,20-diene-3,6-dione.

In mammals, external chemosensory signals from conspecifics of the opposite sex acting on vomeronasal organ receptors can modulate the release of gonadotropins. There is developmental, anatomical and functional evidence showing that the human vomeronasal organ (VNO) has the characteristics of a chemosensory organ. We have been using naturally occurring human pheromones to serve as models for designing novel synthetic compounds that we call vomeropherins. In previous publications we reported that vomeropherin pregna-4,20-diene-3,6-dione (PDD) delivered to the VNO of normal female and male human volunteers significantly affected male subjects only, decreasing respiration and cardiac frequency, augmenting alpha brain waves, and significantly decreasing serum luteinizing hormone (LH) and follicle stimulating hormone (FSH). Results of the present work confirm that PDD produces a local dose-dependent effect in the male human VNO. This is followed by a mild parasympathomimetic effect characterized by 10% increase of vagal tone, together with decreased frequency of electrodermal activity events. Furthermore, PDD locally delivered to the male human VNO significantly decreases serum LH and testosterone (p < 0.01). The present results contribute additional evidence supporting the functionality of the human VNO and its repercussions in autonomic and psychophysiological functions, as well as in neuroendocrine secretions.

Dose-Response Relationship, Drug↗

PubMed2002

The prefrontal cortex in sleep.

Experimental data indicate a role for the prefrontal cortex in mediating normal sleep physiology, dreaming and sleep-deprivation phenomena. During nonrandom-eye-movement (NREM) sleep, frontal cortical activity is characterized by the highest voltage and the slowest brain waves compared to other cortical regions. The differences between the self-awareness experienced in waking and its diminution in dreaming can be explained by deactivation of the dorsolateral prefrontal cortex during REM sleep. Here, we propose that this deactivation results from a direct inhibition of the dorsolateral prefrontal cortical neurons by acetylcholine, the release of which is enhanced during REM sleep. Sleep deprivation influences frontal executive functions in particular, which further emphasizes the sensitivity of the prefrontal cortex to sleep.

Journal Article↗