The EEG was monitored in 56 patients during implantation of an internal cardioverter defibrillator. The purpose of this study was to determine the main EEG frequency ranges that represent ischemic changes during short periods of circulatory arrest. The EEG was recorded with a 16-channel common reference montage (Cz). After onset ...

OBJECTIVES: Breaking the skin when applying scalp electroencephalographic (EEG) electrodes creates the risk of infection from blood-born pathogens such as HIV, Hepatitis-C, and Creutzfeldt-Jacob Disease. Modern engineering principles suggest that excellent EEG signals can be collected with high scalp impedance ( approximately 40 kOmega) without scalp abrasion. The present study ...

The human brain spontaneously generates neural oscillations with a large variability in frequency, amplitude, duration, and recurrence. Little, however, is known about the long-term spatiotemporal structure of the complex patterns of ongoing activity. A central unresolved issue is whether fluctuations in oscillatory activity reflect a memory of the dynamics of ...

During different behavioral states different population activities are present in the hippocampal formation. These activities are not independent: sharp waves often occur together with high-frequency ripples, and gamma-frequency activity is usually superimposed on theta oscillations. There is both experimental and theoretical evidence supporting the notion that gamma oscillation is generated ...

Ten patients with Parkinson's disease were seen following bilateral or unilateral implantation of macroelectrodes into the subthalamic nucleus. Local field potentials (LFPs) were recorded from adjacent subthalamic nucleus macroelectrode (STNME) contacts simultaneously with EEG activity over the supplementary motor (Cz-FCz) and sensorimotor (C3/4-FC3/4) areas and EMG activity from the contralateral ...

OBJECTIVE: Phase coupling between EEG channel pairs in various frequency bands was evaluated during propofol anesthetic induction and recovery periods. METHODS: Twenty-three patients participated in the study. Phase synchronization indices based on the Hilbert transform were investigated on frequency bands 0.05-1 Hz, 1-4 Hz, 4-8 Hz, 8-12 Hz and 12-16 ...

A recent neurophysical model of propagation of electrical waves in the cortex is extended to include a physiologically motivated subcortical feedback loop via the thalamus. The electroencephalographic spectrum when the system is driven by white noise is then calculated analytically in terms of physiological parameters, including the effects of filtering ...

OBJECTIVES: To investigate the physiologic mechanism of human electroencephalogram-electromyogram (EEG-EMG) coherence, the directed transfer function (DTF) based on a multivariate autoregressive (MVAR) model was computed. METHODS: Fifty-six channel EEG and EMG of the right abductor pollicis brevis muscle during a weak tonic contraction were recorded in 6 normal volunteers. The ...

In this paper multivariate spontaneous EEG signals from three broad groups of human subjects--control, seizure, and mania--were studied with the aim of investigating the possible effect of these pathologies on the degree of phase synchronization between cortical areas. The degree of phase synchrony was measured by two recently developed measures ...

This study was designed to locate the neuronal mechanisms of rhythmic activity in the human brain in the alpha-rhythm range using an equivalent dipole model. The experiments approach used here is based on using the "imposed rhythm" phenomenon, whereby a light stimulus flashing with a frequency close to the frequency ...

Recent research has shown that high-frequency, gamma-band electroencephalographic (EEG) oscillations (40-60 Hz) may be an important marker of the conscious state. We compared the ability of the bispectral index (BIS) to distinguish the awake and anaesthetized states during the induction of general anaesthesia with: (i) components of the BIS (BetaRatio, ...

Nonlinear temporal and spatial dynamic changes of human EEG signals during voluntary finger movements were investigated with tracking Kolmogorov entropy (K2). Segments with higher values of K2 defined dynamic transients, distinguishing consecutive phases of the movement organization. The maximum of K2, determined immediately before the movement onset, was specific only ...

BACKGROUND AND OBJECTIVE: Lasers have been used as stimulators for creating pain response without stimulating mechanoreceptive fibers. Various laser systems are still under investigation on the quest for best laser system. Our objective was to test the feasibility of the 980-nm diode laser for LEP (laser evoked potentials) studies. STUDY ...

The study is an attempt to reveal the EEG frequency dynamic changes over sites covering areas reflecting the cognitive processes during movement imagery. Subjects were instructed to imagine a self-paced movement after listening to randomized sentences differing in lack of object or instrument of action. EEG was recorded over frontal, ...

The majority of studies devoted to reveal electrophysiological correlates of words and sentences comprehension, imageability and remembering are based on the event-related potentials and frequency synchronization in different narrow frequency bands. These linear methods reveal some patterns of EEG activity in time and frequency domain. Having in mind that the ...

The development of an electroencephalograph (EEG)-based brain-computer interface (BCI) requires rapid and reliable discrimination of EEG patterns, e.g., associated with imaginary movement. One-sided hand movement imagination results in EEG changes located at contra- and ipsilateral central areas. We demonstrate that spatial filters for multichannel EEG effectively extract discriminatory information from ...

In 13 volunteers, surface EEGs from F(z), C(z), C(3), C(4), and P(z) electrodes and EMG from the flexor digitorum communis were recorded during an experimental task in which the performance of wrist flexion was linked with the selection of a clock sound. In the epoch from 4 to 1 s ...

OBJECTIVES: Spectral power of 40 all-night sleep EEGs (Cz-Pz bipolar lead) recorded in 20 healthy young subjects was calculated after normalization on 30-s consecutive epochs by means of an autocorrelation method based on a 15-order autoregressive model. METHODS: The spectral parameters were calculated for the 7 main EEG bands: slow ...

OBJECTIVES: The spatial aspects of brain electrical activity can be assessed by equivalent EEG frequency band generators. We aimed to describe alterations of these EEG generators in Alzheimer's disease (AD) and healthy aging and whether they could serve as predictive markers of AD in subjects at risk. METHODS: The amplitude ...

To study the functional role of synchronized neuronal activity in the human motor system, we simultaneously recorded cortical activity by high-resolution electroencephalography (EEG) and electromyographic (EMG) activity of the activated muscle during a phasic voluntary movement in seven healthy subjects. Here, we present evidence for dynamic beta-range (16-28 Hz) synchronization ...

Human electroencephalogram (EEG) has been divided in bands established by visual inspection that frequently do not correspond with EEG generators nor with functional meaning of EEG rhythms. Power spectra from wakefulness, stage 2, stage 4 and paradoxical sleep of 8 young adults were submitted to Principal Component Analyses to investigate ...

Arrays of 64 electrodes (8 x 8, 7 x 7 mm) were implanted epidurally on the surface of the visual, auditory or somatosensory cortex of rabbits trained to discriminate conditioned stimuli in the corresponding modality. The 64 electroencephalographic (EEG) traces at all times displayed a high degree of spatial coherence ...

The time dynamics of the quadratic phase coupling within burst patterns during electroencephalic burst-suppression has been quantified. It can be shown that a transient quadratic phase coupling (QPC) exists between the frequency ranges 0 to 2.5 and 3 to 7.5 Hz and between the frequency ranges 0 to 2.5 and ...

OBJECTIVES: The high alpha/low beta range of the spontaneous EEG appears to be particularly sensitive to the effects of nicotine. The present study examined the acute effects of nicotine on the topography of the 13 Hz steady-state visually evoked potential (SSVEP). METHODS: Thirteen moderate smokers participated in a repeated-measures design. ...

OBJECTIVES: The non-linear properties of EEG and filtered rhythms obtained from healthy subjects and epileptic patients with complex partial seizures were analyzed to investigate whether EEG in different neurological states can be generated by the mechanism that integrates several non-linear dynamic systems. METHODS: The control EEG (from 26 healthy subjects), ...

Six participants varying in degree of hypnotizability (2 lows, 2 mediums, and 2 highs) were exposed to 3 20-minute sessions of a binaural-beat sound stimulation protocol designed to enhance theta brainwave activity. The Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C) was used for pre- and post-stimulus measures of hypnotic susceptibility. ...

Investigations using hippocampal slices maintained in vitro have demonstrated that bursts of oscillatory field potentials in the gamma frequency range (30-80 Hz) are followed by a slower oscillation in the beta 1 range (12-20 Hz). In this study, we demonstrate that a comparable gamma-to-beta transition is seen in the human ...

BACKGROUND: Principal component analysis is a multivariate statistical technique to facilitate the evaluation of complex data dimensions. In this study, principle component analysis was used to reduce the large number of variables from multichannel electroencephalographic recordings to a few components describing changes of spatial brain electric activity after intravenous clonidine. ...

The reactivity of different narrow electroencephalographic (EEG) frequencies (4-6, 6-8, 8-10 and 10-12 Hz) to three types of emotionally laden film clips (aggressive, sad, neutral) were examined. We observed that different EEG frequency bands responded differently to the three types of film content. In the 4-6 Hz frequency band, the ...

Cognitive processing involves gamma-activation over broad cortical regions. Phase coupling of these activities has rarely been reported for areas far apart. Other forms of coupling are generally not detected by conventional measures. Here, we use amplitude envelope correlation (AEC), which can detect signal coupling without phase coherence, even among different ...

Repetitive high intensity (110 dB) sound stimulation induces a forebrain-kindling phenomenon in animals predisposed to sound induced seizures. Wistar audiogenic rats (WARs) have been reported to develop a mixed brainstem-limbic seizure pattern, after more than five to ten stimuli. Besides the original brainstem wild running and tonic-clonic seizures, new behavioral ...

The Bispectral Index or "BIS" is a single number, composed from different EEG features, using multivariate statistical methods. It was designed for monitoring the depth of hypnosis during anaesthesia and sedation. Empirically derived from the EEGs of more than 5,000 anaesthetised patients, the BIS reflects the effect of anaesthetics on ...

We show that the supernovae results, which imply that there is evidence for an accelerating universe, may be closely related to the recent discovery of redshift dependence in the fine-structure constant alpha. The link is a class of varying speed-of-light (VSL) theories that contain cosmological solutions that are similar to ...

Since the first observation of perceptual reversal by Necker, many theoretical approaches have been proposed. In a previous study, we showed that a positive wave appeared approximately 250 ms prior to the button press of the subjects, indicating perceptual reversal during the observation of the Necker cube figure. A basic ...

Alpha-band (8-14 Hz) oscillatory EEG activity was examined with high-density scalp electrical recording during the cue-stimulus interval of an endogenous spatial cueing paradigm. In different blocks, cued spatial locations (left or right) were in either the upper or lower visual field, and attended stimuli were either oriented Ts or moving ...

PURPOSE: We investigated neocortical seizure-onset patterns recorded by intracranial EEG with regard to anatomic location, pathologic substrate, and prognostic value for surgical outcome. METHODS: Seizure onset was analyzed in 53 neocortical resective epilepsy surgery patients. Anatomic location was divided into temporal and extratemporal. Pathologic substrate was classified as developmental, mature, ...

A patient with a right occipital arterio-venous malformation (AVM) and seizures heralded by "lights", and experiencing "ecstasy" underwent a right occipital lobectomy after the AVM was embolized. Thereafter, seizures began with motor arrest and lip smacking, but never again with "light and ecstasy". A right temporal lobectomy and electrocorticogram (E.Co.G) ...

People can learn to control the 8-12 Hz mu rhythm and/or the 18-25 Hz beta rhythm in the EEG recorded over sensorimotor cortex and use it to control a cursor on a video screen. Subjects often report using motor imagery to control cursor movement, particularly early in training. We compared ...

The focus of this study is to investigate the relations that exist between changes in the orientation of simple visual stimuli displayed to a subject and the induced changes in brain activity recorded as EEG signals. These signals are recorded using the Electric Source Imaging with 256 electrodes (ESI-256). The ...

OBJECTIVES: The present study was designed to investigate the attentional modulation of gamma band responses in a visual spatial attention task using a 128-channel-EEG-montage. METHODS: Colored rectangles were presented on a screen. After 500 ms an arrow indicated whether subjects had to shift their attention to the left or right ...

This EEG study was performed to clarify the time course of brain electrical events and possible vigilance changes associated with perceptual flips during multistable perception. 13 healthy subjects (28.5 3.8 years) were recorded with a 21-channel digital EEG during a stroboscopic alternative motion paradigm implying illusionary motion with ambiguous direction. ...

BACKGROUND: Activation of autonomic nervous system is common with seizures. No reliable biological markers of impending seizures have been found. Evaluation of autonomic changes might help elucidate the transition from interictal to ictal states. METHODS: We studied twelve patients (eight females, four males), from 19 to 62 years old with ...

BACKGROUND: Activation of autonomic nervous system is common with seizures. No reliable biological markers of impending seizures have been found. Evaluation of autonomic changes might help elucidate the transition from interictal to ictal states. METHODS: We studied twelve patients (eight females, four males), from 19 to 62 years old with ...

The capacity of working memory (WM) for up to about seven simple items holds true both for humans and other species, and may depend upon a common characteristic of mammalian brains. This paper develops the conjecture that each WM item is represented by a different brain wave frequency. The binding-by-synchrony ...

A replication of Wertheim's (1981) visual pursuit tracking study examined the reactivity of the posterior EEG alpha rhythm to two tracking tasks. Twelve subjects visually tracked a light spot moving in a predictable or an unpredictable path. The EEG was recorded from O1, O2, P3, P4, T5, and T6, referenced ...

OBJECTIVES: The objectives were to assess life-span alterations in intrasubject variability of EEG spectral amplitudes and in amplitude and mean frequency computed from spectral amplitude profiles. METHODS: EEG was recorded from the central and occipital scalp of 222 healthy males aged 4 to 90 years. Amplitude spectral profiles derived from ...

An automatic EEG pattern detection unit was developed and tested for the recognition of burst-suppression periods and for the separation of burst from suppression patterns. The median, standard deviation and the 95% edge frequency were computed from single channels of the EEG within a moving window and completed by the ...

OBJECTIVES: The goal of this study was to determine the relation between EEG, event-related potentials and information processing as measured by an acoustical choice reaction time task. In particular, we wanted to find out to what extent reaction-time performance is related to the pre-stimulus EEG activity (frequency domain) and the ...

PURPOSE: Conventional scalp and intracranial EEG is recorded within a limited band of frequencies (0.3-70 Hz) based on the premise that clinically relevant cerebral activity occurs within this frequency range. Ikeda et al. recently demonstrated focal very low frequency activity (VLFA), <0.3 Hz, at seizure onset for both intra- and ...

A 1-Hz rhythmic event-related potential was recorded at the scalp during performance of a 0.5-Hz tracking task. At cortical motor areas, negative peaks occurred 10-20 ms after peak tracking speeds. Analysis of single sweeps suggested that EEG phase was reset at initiation of the tracking motion and then maintained a ...