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At least 19 recordsLinked to original sources
PubMed1998

Noise sustained waves in subexcitable media: From chemical waves to brain waves.

We discuss a novel type of spatiotemporal pattern that can be observed in subexcitable media when coupled to a thermal environment. These patterns have been recently observed in several different types of systems: a subexcitable photosensitive Belousov-Zhabotinsky reaction, hippocampal slices of rat brains, and astrocyte syncytium. In this paper, we introduce the basic concepts of subexcitable media, describe recent experimental observations in chemistry and neurophysiology, and put these observation into context with computer simulations. (c) 1998 American Institute of Physics.

Journal Article↗
PubMed1999

Brain waves and brain wiring: the role of endogenous and sensory-driven neural activity in development.

Neural activity is critical for sculpting the intricate circuits of the nervous system from initially imprecise neuronal connections. Disrupting the formation of these precise circuits may underlie many common neurodevelopmental disorders, ranging from subtle learning disorders to pervasive developmental delay. The necessity for sensory-driven activity has been widely recognized as crucial for infant brain development. Recent experiments in neurobiology now point to a similar requirement for endogenous neural activity generated by the nervous system itself before sensory input is available. Here we use the formation of precise neural circuits in the visual system to illustrate the principles of activity-dependent development. Competition between the projections from lateral geniculate nucleus neurons that receive sensory input from the two eyes shapes eye-specific connections from an initially diffuse projection into ocular dominance columns. When the competition is altered during a critical period for these changes, by depriving one eye of vision, the normal ocular dominance column pattern is disrupted. Before ocular dominance column formation, the highly ordered projection from retina to lateral geniculate nucleus develops. These connections form before the retina can respond to light, but at a time when retinal ganglion cells spontaneously generate highly correlated bursts of action potentials. Blockade of this endogenous activity, or biasing the competition in favor of one eye, results in a severe disruption of the pattern of retinogeniculate connections. Similar spontaneous, correlated activity has been identified in many locations in the developing central nervous system and is likely to be used during the formation of precise connections in many other neural systems. Understanding the processes of activity-dependent development could revolutionize our ability to identify, prevent, and treat developmental disorders resulting from disruptions of neural activity that interfere with the formation of precise neural circuits.

Aging↗
PubMed1978

The relationship of head size to alpha frequency with implications to a brain wave model.

Analogies between brain waves and waves in physical systems suggest that EEG frequency may be partly determined by cortical surface area. Since a number of other physiological and anatomical parameters probably influence EEG frequency, only a weak correlation is to be expected. A study was made of 159 subjects, some of whom had either very large or very small heads. A single number representing head size was determined as the cube root of three linear measurements. Several characteristic EEG frequencies were determined for each subject by means of Fourier analysis. The data indicate that alpha frequency is significantly correlated with head size: larger heads tend to produce slower alpha rhythms. It was also shown that alpha frequency tends to be lower in all subjects above roughly age 60. Subjects above produced significantly less alpha rhythm than the younger group. It is suggested that analogies between brain waves and physical waves may explain a number of phenomena which are typical of EEG.

Adolescent↗
PubMed1998

Brain-wave recognition of sentences.

Electrical and magnetic brain waves of two subjects were recorded for the purpose of recognizing which one of 12 sentences or seven words auditorily presented was processed. The analysis consisted of averaging over trials to create prototypes and test samples, to each of which a Fourier transform was applied, followed by filtering and an inverse transformation to the time domain. The filters used were optimal predictive filters, selected for each subject. A still further improvement was obtained by taking differences between recordings of two electrodes to obtain bipolar pairs that then were used for the same analysis. Recognition rates, based on a least-squares criterion, varied, but the best were above 90%. The first words of prototypes of sentences also were cut and pasted to test, at least partially, the invariance of a word's brain wave in different sentence contexts. The best result was above 80% correct recognition. Test samples made up only of individual trials also were analyzed. The best result was 134 correct of 288 (47%), which is promising, given that the expected recognition number by chance is just 24 (or 8.3%). The work reported in this paper extends our earlier work on brain-wave recognition of words only. The recognition rates reported here further strengthen the case that recordings of electric brain waves of words or sentences, together with extensive mathematical and statistical analysis, can be the basis of new developments in our understanding of brain processing of language.

Adult↗
PubMed1999

Invariance between subjects of brain wave representations of language.

In three experiments, electric brain waves of 19 subjects were recorded under several different experimental conditions for two purposes. One was to test how well we could recognize which sentence, from a set of 24 or 48 sentences, was being processed in the cortex. The other was to study the invariance of brain waves between subjects. As in our earlier work, the analysis consisted of averaging over trials to create prototypes and test samples, to both of which Fourier transforms were applied, followed by filtering and an inverse transformation to the time domain. A least-squares criterion of fit between prototypes and test samples was used for classification. In all three experiments, averaging over subjects improved the recognition rates. The most significant finding was the following. When brain waves were averaged separately for two nonoverlapping groups of subjects, one for prototypes and the other for test samples, we were able to recognize correctly 90% of the brain waves generated by 48 different sentences about European geography.

Brain↗
PubMed1999

Invariance of brain-wave representations of simple visual images and their names.

In two experiments, electric brain waves of 14 subjects were recorded under several different conditions to study the invariance of brain-wave representations of simple patches of colors and simple visual shapes and their names, the words blue, circle, etc. As in our earlier work, the analysis consisted of averaging over trials to create prototypes and test samples, to both of which Fourier transforms were applied, followed by filtering and an inverse transformation to the time domain. A least-squares criterion of fit between prototypes and test samples was used for classification. The most significant results were these. By averaging over different subjects, as well as trials, we created prototypes from brain waves evoked by simple visual images and test samples from brain waves evoked by auditory or visual words naming the visual images. We correctly recognized from 60% to 75% of the test-sample brain waves. The general conclusion is that simple shapes such as circles and single-color displays generate brain waves surprisingly similar to those generated by their verbal names. These results, taken together with extensive psychological studies of auditory and visual memory, strongly support the solution proposed for visual shapes, by Bishop Berkeley and David Hume in the 18th century, to the long-standing problem of how the mind represents simple abstract ideas.

Adult↗
PubMed2004

Levels of brain wave activity (8-13 Hz) in persons with spinal cord injury.

STUDY DESIGN: Brain wave activity in people with spinal cord injury (SCI) was compared to brain wave activity in able-bodied controls. OBJECTIVES: To investigate whether a spinal injury results in changes in levels of brain wave activity in the 8-13 Hz spectrum of the electroencephalography (EEG). SETTING: Sydney, Australia. METHODS: Monopolar, multichannel EEG assessment was completed for 20 persons with SCI and 20 able-bodied, sex- and age-matched controls. A total of 14 channels of EEG were measured across the entire scalp for all participants. Comparisons between the able-bodied and SCI participants were made across the frontal, central, parietal, occipital and temporal regions. Comparisons were also made for impairment level, that is, between participants with tetraplegia and paraplegia. RESULTS: Compared to the able-bodied controls, consistently reduced brain wave activity (measured by magnitude and peak amplitude) in the 8-13 Hz component of the EEG occurred in persons with SCI across all regions and sites, and differences were larger in the central, parietal and occipital sites. The SCI group also had consistently lower frequencies than the able-bodied controls. Furthermore, the subgroup of SCI participants with tetraplegia generally had significantly reduced brain activity (magnitude and peak amplitude) compared with the paraplegic subgroup and able-bodied controls. CONCLUSIONS: The findings of this research enhance our understanding of changes in brain wave activity that could be associated with deafferentation that occurs following SCI, as well as provide essential data on the potential of SCI persons to use a 'hands free' environmental control system that is based upon 8-13 Hz brain activity.

Action Potentials↗
PubMed1998

New methods for three dimensional mapping of brain waves.

The representation of spatiotemporal pattern of brain electrical activity is an important issue in the research of neural assemblies. This paper describes methods of parametric 3D head or brain modeling and its corresponding interpolation for functional imaging based on brain waves. The 3D interpolation method is an extension of cortical imaging technique. It can be used with features of either transformed domains or higher order statistics of brain waves on realistic head or brain models. The simulating result suggests that it is a better method in comparison with the global nearest neighbor technique. With those techniques, an example of brainwave imaging was given using partial coherence of event-related potentials estimated by multivariate autoregressive model.

Brain Mapping↗
PubMed1994

Brain wave synchronizers: Part 1--Review of the literature and the first dental anxiety study.

Using specific frequencies, photostimulation was developed into units known as brain wave synchronizers. Medical literature has shown the results of brain wave synchronizer use in obstetrics during labor and delivery, as an aid in anesthesiology, and for hypertension control. Dental studies have been conducted using brain wave synchronizers to relax patients during anxiety-inducing endodontic treatment. The first part of this article will review the medical and dental literature on brain wave synchronizers and the first brain wave synchronizer study on dental patients.

Cortical Synchronization↗
PubMed1997

Brain wave recognition of words.

Electrical and magnetic brain waves of seven subjects under three experimental conditions were recorded for the purpose of recognizing which one of seven words was processed. The analysis consisted of averaging over trials to create prototypes and test samples, to both of which Fourier transforms were applied, followed by filtering and an inverse transformation to the time domain. The filters used were optimal predictive filters, selected for each subject and condition. Recognition rates, based on a least-squares criterion, varied widely, but all but one of 24 were significantly different from chance. The two best were above 90%. These results show that brain waves carry substantial information about the word being processed under experimental conditions of conscious awareness.

Brain↗
PubMedDate not supplied

Mapping of somato-sensory evoked potentials (SEP): new findings suggesting the role of brain waves as a "temporal analyzer of the stimulus".

For a number of years we have been reporting a relationship between the mid components of the somato-sensory evoked potentials and basic brain waves. Recently we suggested that when the primary spike occurs it elicits a train consisting of beta, alpha, theta and delta single waves, originating at the same point in time and overlapping one with the other. The half periods of each of these waves are equal to the latencies of mid and late SEP components. Thus the latter are in fact the classical brain waves. They are present bilaterally but are of higher amplitude on the parietal region contralateral to the side of the stimulus applied to the median nerve. Presumably at that side the brain wave amplitude is increased by the delayed potentials due to the conduction of some components of the signal travelling in the thin myelinated fibers. Indeed this study revealed the presence of recurrent delayed positive and negative foci in the parietal region contralateral to the side of the stimulus in addition to the late vertex components. Thus brain waves contribute to the temporal analysis of the stimulus.

Adolescent↗
PubMed1999

Hypothesized neural dynamics of working memory: several chunks might be marked simultaneously by harmonic frequencies within an octave band of brain waves.

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 hypothesis, now being widely investigated, holds that the attributes of a single cognitive element cohere because electroencephalogram (EEG) synchrony temporarily unifies their substrates, which are distributed among different brain regions. However, thought requires keeping active more than one cognitive element, or WM "chunk," at a time. If there is indeed a brain wave frequency code for cognitive item-representations that are copresent within the same volume of neural tissue, the simple mathematical relationships of harmonies could provide a basis for maintaining distinctness and for orderly changes. Thus, a basic aspect of music may provide a model for an essential characteristic of WM. Music is a communicative phenomenon of "intermediate complexity," more highly organized than the firing patterns of individual neurons but simpler than language. If there is a distinct level of neural processing within which the microscopic physiological activity of neurons self-organizes into the macroscopic psychology of the organism, it might require such moderate complexity. Some of the obvious properties of music--orderly mixing and transitions among limited numbers of signal lines-are suggestive of properties that a dynamic neural process might need in order to organize and reorganize WM markers, but there are a number of additional, nonobvious advantageous properties of summating sinusoids in music-like relationships. In particular, harmonies register a stable periodic signal in the briefest possible time. Thus, the regularity of summating sinusoids whose frequencies bear harmony ratios suggests a particular kind of tradeoff between parallel and serial processing. When there are few copresent waves, at EEG frequencies, this sort of parallel coding retains behaviorally meaningful brief periods. A necessary companion hypothesis is that the brain wave frequencies underlying WM are confined to a single octave; that is, the upper and lower bounds of the band are in the ratio of 2:1. This hypothesized restriction, suggested by an empirical property of EEG bands that has been widely reported but rarely commented upon, has the important property of precluding spurious difference rhythms. A restriction to an octave, of "harmonious" frequency-markers for WM items, also seems consistent with a great deal of behavioral data suggesting that WM comprises a rapidly fading trace process in which only up to three or four item-representations are strongly activated simultaneously. There is also an additional, sequential renewal-or-revision process, within which up to another three or four items are being actively refreshed by rehearsal or replaced. Such serial processing may involve a less stringent octave band crowding problem.

Animals↗
PubMed1994

Brain wave synchronizers: Part 2--A pilot EEG study and a clinical observational study.

In the first brain wave synchronizer study by our group at Temple University (the readers are referred to part 1, which appeared in the January 1994 issue of The Compendium), patients undergoing endodontic therapy were divided into three groups: the Relaxodont unit, the Relaxodont unit with a relaxation tape, and a control group. The anxiety levels of the groups were compared using galvanic skin resistance, pulse rate, subjective response, and physical reactions. The results showed that the two Relaxodont groups did significantly better than the control group. In part 2, a pilot brain wave synchronizer electroencephalogram study is presented. The results of a clinical observational study on endodontic patients by our group at Temple University using simple chairside means to assess anxiety is also presented.

Adult↗
PubMed1960

Simultaneous study of behavior and brain waves.

A technique for the simultaneous audiovisual recording of behavior and brain waves is described. The absence of muscle movement artifact, despite unlimited activity of the patient, suggests that telemetering may be adaptable for routine electroencephalography.

Artifacts↗