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Results for “Brain waves”

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At least 217 records · Page 12Linked to original sources

PubMed1995

The origin of the human auditory brain-stem response wave II.

Auditory brain-stem responses (ABRs) were recorded from human subjects undergoing neurosurgical procedures which exposed the auditory nerve. Scalp recordings indicated that the latency of the negativity between waves I and II (In) and the latency of positive peak II (IIp) were shorter when the nerve was suspended in air than when the nerve was submerged in cerebrospinal fluid or saline, while earlier and later waves remained unaffected. These results could not be attributed to changes in stimulus or recording parameters or conduction velocity. Computational and somatosensory experimental evidence of stationary potentials generated by physical properties of the volume conductor, including changes in conductivity or geometry, are presented to develop a model of wave IIp generation. The results of this study suggest that wave IIp (and probably In) are manifestations of current flux asymmetries across conductivity boundaries created by the temporal bone-cerebrospinal fluid intradural space-brain-stem interfaces. The current flux asymmetries are generated as the propagating auditory nerve action potential crosses the conductivity boundaries. These results also indicate that the physical characteristics of the volume conductor and neural pathways must be considered when interpreting surface recorded evoked potentials.

Action Potentials↗

PubMed1992

Interaction of click intensity and cochlear hearing loss on auditory brain stem response wave V latency.

Auditory brain stem responses (ABRs) to 95, 80, 60, 40, and 30 dB nHL clicks were retrospectively studied from 103 patients (194 ears) with various degrees of cochlear impairment. Hearing loss and sample size were balanced across gender. Results indicate that the slope of the wave V latency versus 4000 Hz hearing loss function doubles as click intensity is decreased from 80 (0.01 msec/dB HL) to 60 nHL (0.02 msec/dB HL). Overall results indicate a slope increase of 0.0004 msec for each decibel decrease in click intensity from 95 to 30 dB nHL. Intersubject variability increased with increased hearing loss and/or decreased stimulus intensity. The effects of hearing loss on wave V latency are minimal, and intersubject variability is less if high-intensity clicks (greater than or equal to 95 dB nHL) are used. No differences in the effects of hearing loss on wave V latency were seen between males and females. Latency corrections for cochlear hearing loss should, therefore, consider stimulus intensity.

Acoustic Stimulation↗

PubMed1978

Low power radio-frequency and microwave effects on human electroencephalogram and behavior.

In a pilot study of ten human subjects, temporary changes in brain waves and behavior were seen on exposure to power densities lower than 10(-12) W/cm2, which is substantially below typical urban levels. Frequencies included .1 to 960 MHz continuous and 8.5 to 9.6 GHz pulse-modulated waves. Since the relaxation frequency of protein-bound water is considered to fall between 100 and 1,000 MHz, absorptions and quantum effects may be the mechanistic basis for the electroencephalogram changes observed in most of the subjects produced by 10(-15) W/cm2 cw radio-frequency energy of between 130 and 960 MHz. Constructive and destructive interference patterns from standing waves within the skull possibly interact with the bioelectric generators in the brain, since electroencephalogram wave amplitudes and frequencies increased or decreased respectively at different radio wavelengths.

Adolescent↗

PubMed2005

The physical basis of alpha waves in the electroencephalogram and the origin of the "Berger effect".

Synchronised activity, differing in phase in different populations of neurons, plays an important role in existing theories on the function of brain oscillations (e.g., temporal correlation hypothesis). A prerequisite for this synchronisation is that stimuli are capable of affecting (resetting) the phase of brain oscillations. Such a change in the phase of brain waves is also assumed to underlie the "Berger effect": when observers open their eyes, the amplitude of EEG oscillations in the alpha band (8-13 Hz) decreases significantly. This finding is usually thought to involve a desynchronisation of activity in different neurons. For functional interpretations of brain oscillations in the visual system, it therefore seems to be crucial to find out whether or not the phase of brain oscillations can be affected by visual stimuli. To answer this question, we investigated whether alpha waves are generated by a linear or a nonlinear mechanism. If the mechanism is linear - in contrast to nonlinear ones - phases cannot be reset by a stimulus. It is shown that alpha-wave activity in the EEG comprises both linear and nonlinear components. The generation of alpha waves basically is a linear process and flash-evoked potentials are superimposed on ongoing alpha waves without resetting their phase. One nonlinear component is due to light adaptation, which contributes to the Berger effect. The results call into question theories about brain-wave function based on temporal correlation or event-related desynchronisation.

Adult↗

PubMed1979

Cerebral hemodynamic changes during plateau waves in brain-tumor patients.

The plateau wave, one of the wave forms observed in patients with increased intracranial pressure, has previously been extensively investigated, but its pathophysiological aspect is as yet unclear. The authors undertook a study of cerebral hemodynamic changes while the plateau waves were observed in five brain-tumor patients. Although the number of cases studied was small, a remarkable decrease in cerebrovascular resistance was seen in all patients during the plateau waves. It is suggested that the plateau waves are caused by a marked cerebral vasodilatation. The present results support the thesis that cerebral blood volume is increased during the plateau waves. The plateau waves are closely related to the intrinsic vasomotor control of cerebral circulation, and can occur as long as cerebral vasodilating ability is maintained, irrespective of the existence of cerebral autoregulation.

Adult↗

PubMed1963

Variations in alpha voltage of the electroencephalogram and time perception.

Human subjects were instructed to respond regularly at 3-second intervals while their brain waves were recorded and analyzed. When subjects were alert the time between two successive responses did not vary greatly; however, as subjects became increasingly drowsy these times lengthened and the mean voltage of the peak alpha frequency decreased.

Brain Waves↗

PubMed1963

Electroencephalographic responses to ionizing radiation.

Electroencephalographic recordings made from chronically implanted cortical electrodes indicate that ionizing radiation has an immediate effect upon brain wave patterns. X-rays delivered at the rate of 0.2 roentgen per second produce an arousal effect resembling that which occurs as a result of stimulation through peripheral receptor systems.

Arousal↗

PubMed1989

Persistent hypersynchronization of neocortical neurons in the mocha mutant of mouse.

A recessive mutation in the mouse at the mocha locus (mh, chromosome 10) modulates the synchronous synaptic activation of neocortical neurons, resulting in a constant 6-7 Hz (theta) wave pattern in the electrocorticogram. The gene-linked brain rhythm is unaffected by motor behavior and cannot be desynchronized by sensory stimuli. This exemplary neurological mutation affecting cortical excitability is the first to reveal clearly that the predominance of a specific pattern of spontaneous brain wave activity can be inherited as a recessive trait.

Animals↗

PubMed2005

Assessment of brain activities in immersive environments.

The primary goal of this study was to establish an objective baseline for subjects who participated in a study in an immersed environment created for the virtual reality therapy (VRT) situation. Since the effects of VRT on the subjects treated for neurosis have traditionally been measured by subjective measurements, there is a need to include objective measures. This will improve and validate the effectiveness of VRT. Fifteen college students participated in this study. Specifically, the researchers measured the activity of the subjects' brainwaves in response to the VRT using EEG technology. The preliminary data indicated that, in most cases, subjects had a decline in brain wave activity between what is deemed a normal / baseline brain activity and the brainwave activity recorded when they were when they were connected to the virtual reality equipment and under influence of an immersive scene. In rare instances, there were some subjects that showed extreme increases in brain activities. In addition, the data indicated that, in most cases, subjects are more relaxed while under the immersive influence with respect to brain activities than those that are not.

Brain↗

PubMed2006

Napoleon Cybulski--Polish pioneer in developing of the device for measuring blood flow velocity.

Napoleon Cybulski (1854-1919) was the most prominent Polish physiologist who chaired the Department of Physiology at the Faculty of Medicine of Jagiellonian University between 1885 and 1919. One of his greatest achievements was the construction of a device for precise measurements of blood movement in the vessels - the photohemotachometer, which provided a better insight into the physiology and pathophysiology of the circulatory system. In the field of endocrinology Cybulski together with Szymonowicz, found out that adrenal extracts contain biologically active substances that elevate blood pressure. He was also a constructor of an extremely clever microcalorimeter to measure the quantity of heat produced during isolated muscle contraction. He applied, for the first time, condensator discharges to stimulate nerves and analyzed changes in the excitability of the muscles. Cybulski proved that the cause of the electrical excitability of tissue depends on the electrical energy and the time of its duration. Together with Beck, he performed the experiments on the sensory centers in the central nervous system by means of the observations of the electrical evoked potentials. They discovered the continuous electrical oscillations in the brain - the brain waves and recorded the negative electrical potentials in certain brain areas induced by sensory impulses coming from the periphery. Using this technique Beck and Cybulski localized various centers in the brain of dogs and Macaccus rhesus monkeys. The names of Beck and Cybulski were quoted in many publications on neurophysiology and electroencephalography. The present paper describes Napoleon Cybulski as a constructor of an original instrument for studying the movement of blood under various experimental conditions an emphasizes the contribution of this invention to the development of physiology.

Blood Circulation↗

PubMed2001

Brain potentials in human patients with extremely severe diffuse brain damage.

To test higher cortical functions of neurological patients, oddball tasks are often used in which a frequent and a rare stimulus are randomly presented and a P3 brain wave is recorded to the rare stimulus. We examined 33 patients with extremely severe brain injury. Three oddball conditions were used: with two sine tones (ST), with two complex tones (CT) and with vowels 'o' and 'i'. Across all patients, CT elicited P3 more often than ST, and the occurrence of the P3 after vowels was intermediate. However, among patients who showed a distinct P3 wave, its amplitude in the subgroup with traumatic brain injury was larger to vowels than to CT. In patients with non-traumatic etiology, CT and vowels elicited a P3 of a nearly equal amplitude. Stimuli of sufficient complexity should be used when the P3 technique is applied for assessment of cortical functions in severely impaired patients.

Adolescent↗

PubMed1980

Immunologic studies in schizophrenic and control subjects.

Heath and coworkers proposed that schizophrenia may be an autoimmune disorder in which antibodies are built up against specific substances in certain brain cells. Heath reports that schizophrenic patients exhibit abnormal brain waves in recordings from the caudate nucleus and septal area. These abnormal waves can also be recorded from similar sites in monkey brains after injections into the lateral ventricle cerebrospinal fluid of gamma-G-immunoglobulins (IgG) isolated from the blood of acutely ill schizophrenic patients. We prepared IgG fractions from control subjects and acutely ill schizophrenic patients and tested them in rhesus monkeys under double-blind conditions. Of 107 sera tested from 24 schizophrenic patients, 29 produced positive electroencephalographic recordings in the monkeys. From 30 control subjects we tested 80 samples and found 6 to be positive according to Heath's criteria. This amounts to more than 1 positive reaction for every 4 schizophrenic patients' fractions tested and approximately 1 positive in 13 from control subjects' serum fractions. The difference between control and patient groups is highly significant (p less than 0.001). Although our results confirm the experimental findings of the Heath group concerning abnormal EEG activity associated with an IgG fraction from schizophrenic patients, they differ from Heath's results for fractions from control persons. We found positive effects from a small number of control fractions whereas Heath claims never to have observed positive biological activity in control fractions. The autoimmune hypothesis has numerous drawbacks, the greatest of which is the inability to demonstrate the presence of circulating antibody in schizophrenic patients with the use of standard immunologic techniques.

Acute Disease↗

PubMed2025

Personalized Repetitive Transcranial Magnetic Stimulation (PrTMS®) Coupled with Transcranial Photobiomodulation (tPBM) For Co-Occurring Traumatic Brain Injury (TBI) and Post-Traumatic Stress Disorder (PTSD).

This study provides further evidence demonstrating the beneficial effects of PrTMS® treatment in co-occurring disorders. Furthermore, this study illustrates the benefit of augmenting PrTMS® with tPBM for superior outcomes. The positive results of this novel case study can be attributed to brain wave neuromodulation and increased neuronal ATP production, resulting in synergistic enhanced neuroplasticity and brain optimization. Further, large-scale, randomized and blinded studies are recommended to validate our promising preliminary observations utilizing multifaceted interventions for co-occurring disorders.

Co-Occurring Disorders↗

PubMed1998

[The influence of sleep breathing disorder on growth hormone secretion in children with tonsil hypertrophy].

INTRODUCTION: Recently it has been revealed that Obstructive Sleep Apnea Syndrome has an influence on the endocrine system, especially to the secretion of growth hormone (GH). It was previously reported that secretion of GH has a circadian rhythm along with a correlation with slow wave sleep. Normally in a pediatric patient, after 90 min of sleep the brain wave shows patterns of deep sleep, and a matching peak in GH secretion is observed. We have studied the effect of GH secretion in sleep breathing disorder of pediatric patients by observing the pre- and post-operative difference in GH secretion in children with tonsillar hypertrophy who had tonsillectomies. MATERIAL AND METHODS: Ten pediatric patients who complained of sleep apnea or hypopnea, and were highly suspected of having sleep breathing disorders due to tonsil hypertrophy and underwent surgery were chosen. Pre and post-operative blood somatomedin C and urinary growth hormone levels were measured. In 6 of the 10 patients blood GH levels were measured after overnight collection of blood every 30 min through a catheter placed in the vein. METHOD OF ANALYSIS: Integral blood GH calculated from GH levels of the blood samples taken every 30 min was used to express the efficacy of GH secretion during sleep, and was compared with blood somatomedin C and urinary GH levels. Pre- and post-operative somatomedin C and urinary GH measurements were compared. RESULT: 1) In 6 of the 10 patients, there was a positive correlation with integral GH and urinary GH, and no correlation with integral GH or somatomedin C. 2) Post-operatively, 7 of the 10 patients had increased urinary GH levels, 1 showed no change and 2 had decreased levels. There was a significant increase in the mean urinary GH levels from 18.6 +/- 16.1 pg/ml pre-operatively to 35.8 +/- 19.6 pg/ml post-operatively (P < 0.05). 3) Eight of the 10 patients had a post-operative increase in somatomedin C levels, 1 showed no change and the other patient had a decreased level. There was a significant increase in mean somatomedin C levels from 175.9 +/- 124.8 ng/ml pre-operatively to 226.6 +/- 134.3 ng/ml post-operatively (P < 0.01). CASE: An 8-year-old-boy was diagnosed as having habitual tonsillitis and suspected sleep breathing disorder, and was admitted to our hospital for a tonsillectomy. Apnea and hypopnea were observed during sleep in the hospital. After receiving his parents' consent, GH secretion was evaluated before and after the tonsillectomy. Integrated GH measurements, somatomedin C and urinary GH increased significantly after the operation. CONCLUSION: In this study, the improvement of sleep breathing disorder by surgery was associated with a positive effect to the GH secretion. GH secretion is important for growth of a child. Wen the cause of sleep breathing disorder is evident in the upper airway system, active treatment and cure by surgery is advised. Measurement of urinary GH in the morning is useful and simple for evaluating the ability to secrete GH.

Biomarkers↗

PubMed2006

[Nonlinear dynamics characteristics in alpha rhythm of scalp electroencephalogram].

In regard to the controls and schizophrenia EEGs, we have got alpha rhythm from three points of view and verified the nonlinearity of the three kinds of rhythms. The results show that neither normal EEG alpha nor patients EEG alpha have the typical nonlinear characteristics. Therefore, we could not blindly use the theories of nonlinear dynamics to analyze the rhythm of brain wave.

Alpha Rhythm↗

PubMed2000

The forward EEG solutions can be computed using artificial neural networks.

Study of electroencenphalography (EEG) is the one of the most utilized methods in both basic brain research and clinical diagnosis of neurological disorders. Recent technological advances in computer and electronic systems have allowed the EEG to be recorded from large electrode arrays. Modeling the brain waves using a head volume conductor model provides an effective method to localize functional generators within the brain. However, the forward solutions to this model, which represent theoretical potentials in response to current sources within the volume conductor, are difficult to compute because of time-consuming numerical procedures utilized in either the boundary element method (BEM) or the finite element method (FEM). This paper presents a novel computational approach using an artificial neural network (ANN) to map two vectors of forward solutions. These two vectors correspond to different head models but with respect to the same current source. The input vector to the ANN is based on the spherical head model, which can be computed efficiently but involves large errors. The output vector from the ANN is based on the spheroidal model, which is more precise, but difficult to compute directly using the traditional means. Our experiments indicate that this ANN approach provides a remarkable improvement over the BEM and FEM methods: 1) the mean-square error of computation was only approximately 0.3% compared to the exact solution; 2) the online computation was extremely efficient, requiring only 168 floating point operations per channel to compute the forward solution, and 10.2 K-bytes of storage to represent the entire ANN. Using this approach it is possible to perform real-time EEG modeling accurately on personal computers.

Biomedical Engineering↗

PubMedDate not supplied

In vivo optical reflectance imaging of spreading depression waves in rat brain with and without focal cerebral ischemia.

Spreading depression (SD) waves occur in focal cerebral ischemia of the brain. Optical reflectance imaging at 550 +/- 10-nm wavelength using a charge-coupled device (CCD) camera, called optical intrinsic signal imaging (OISI) in the neuroscience community, provides high resolution imaging of SD waves based on changes in blood perfusion. We present optical images of SD waves in normal rat brain induced by a pinprick, and the spontaneous SD waves that follow middle cerebral artery occlusion (MCAO). The images of change in reflectance are calculated as A = (I-I(o))I(o), where I is pixel intensity as some timepoint and I(o) is the initial intensity just prior to an SD wave. Difference images B = [I(i)-I(i-1)]I(o), where I(i) is the image at time i and I(i-1) is the previous image at time i-1 (a 6.4-s interval), significantly sharpen the boundaries between leading and trailing edges of the SD wave. Maximum rate-of-change images C = max(B) display the maximum pixel value of B within the duration of a single SD wave, and provide an image that visualizes the entire penumbra. The penumbra appear bright due to a rapid drop in perfusion, while the normal brain and infarct area appear dark.

Animals↗

PubMedDate not supplied

Visual slow brain potentials in children with attention deficit disorder.

Using a two-stimulus reaction time paradigm, with two separate reward conditions (contingent and noncontingent), we compared slow wave brain potentials (ERPs) in 144 children with attention deficit disorder (ADD) and 30 normal control children. This article reviews the findings during the 900 msec visual warning stimulus. As we had expected, based on ERP work of Forth and Hare (1989) and Raine, Venables and Williams (1990), and on previous work from our own laboratory, the group differences were found in the negative slow wave portions of the ERP complex during the contingent reward condition but not during the noncontingent condition. Aggressive hyperactive subjects with attention deficit disorder (ADDHA) were discriminated from nonaggressive subjects (including control subjects) during the contingent reward condition in the following ways: (1) greater fronto-central negativity (640-900 msec slow wave) and (2) greater right parietal than left parietal negativity (430-750 msec slow wave). All ADD subgroups, when compared to control (CONTR) subjects, showed greater slow wave negativity (700-900 msec) at the midline occipital electrode site during the contingent reward condition. This could be explained in part as an IQ effect on ERPs reflecting the IQ difference between the ADD subgroups and the controls. These slow wave findings seem to relate to attentional problems of these children. They are discussed in terms of a psychobiological model of inhibition/disinhibition and appetitive activation.

Aggression↗