Brain Electrical Activity Mapping Research Articles

Adequacy of the International 10–20 Electrode System for Computed Neurophysiologic Topography

The adequacy of the International 10-20 System is reviewed in light of demands imposed on the accuracy of lead placement by improvements in spatiotemporal brain electrical activity mapping technology. Computed tomography (CT) and magnetic resonance imaging (MRI) studies reveal that the most frequent sources of inaccuracy of electrode locations are difficulties in defining the inion, variance in the anatomy of the occipital bone, inconspicuous sagittal deformities, variance of sulcal pattern, and brain width asymmetries. Owing to these factors, electrodes placed bilaterally and equidistant from the nasion-inion line may not be homotopically located. Therefore, the authors suggest that practitioners who employ the 10-20 System in order to gain precise and more individualized laterality information do so with extreme caution until the range of placement and interpretative errors is more precisely determined using CT/MRI-assisted EEG.

Electrophysiologic Comparisons Between Two Groups of Patients With Alzheimer's Disease

Two groups of patients with Alzheimer's disease were compared using brain electrical activity mapping. The patients were selected on the basis of their cognitive history. The initial symptom of disease of the patients in group 1 was a significant and profound memory deficit, whereas the patients in group 2 initially presented with a gradually progressive spatial impairment. Fourteen topographic features distinguished the groups. Eleven of the 14 features pertained to electrical activity differences in parietal regions, and 9 were bilateral. These features were highly correlated with cognitive measures that are also useful in distinguishing the groups.

Behavioral and Electrophysiological Evidence for Gestational Age Effects in Healthy Preterm and Fullterm Infants Studied Two Weeks after Expected Due Date

We investigated the effects of gestational age at birth on behavioral and electrophysiological measures of 135 medically healthy infants, studied at 42 weeks postconception, and stratified into 3 groups--early-born preterms, 26-32 weeks (n = 55); middle-group preterms, 33-37 weeks (n = 43); and fullterms, 38-41 weeks (n = 37). Subjects were studied behaviorally with the Assessment of Preterm Infants' Behavior (APIB) and electrophysiologically with brain electrical activity mapping (BEAM). Fullterms showed significantly better behavioral function than both preterm groups. Less difference was found between the preterm groups. EEG spectral and photic evoked response were of significantly less amplitude for the preterms than the fullterms. Path analysis showed gestational age effects on behavioral (3 of 6) and electrophysiological (13 of 17) variables due to postnatal complications. We conclude that some differences attributable to gestational age at birth are explained by the cumulative effect of minor but unavoidable complications associated with premature birth. We speculate that remaining effects may result from developmentally inappropriate sensorimotor stimulation consequent to the premature experience of an extrauterine environment.

Characterization of cortical dopaminergic stimulation using three-dimensional brain electrical activity mapping in healthy volunteers : R. Luthringer, R. Minot, M. Toussaint and J.P. Macher Centre Hospitalier Spécialisé, 68250 Rouffach, France

Characterization of cortical dopaminergic stimulation using three-dimensional brain electrical activity mapping in healthy volunteers : R. Luthringer, R. Minot, M. Toussaint and J.P. Macher Centre Hospitalier Spécialisé, 68250 Rouffach, France

Topographical EEG differences between schizophrenic patients and controls during neuropsychological functional activation

Ten DSM III schizophrenic patients belonging to an Active syndrome were compared with 10 age- and sex-matched normal controls on neuropsychological tests with concurrent monitoring of topographical EEG using a brain imager with a 28-electrode array. In line with predictions, abnormalities in patients were found in tests involving right hemispheric functions. Deficits were found in recognition memory for faces as distinct from a verbal recognition memory task. Right temporo-parietal involvement in the faces task was confirmed by an absence of beta II amplitude reduction in patients compared with controls in the right temporo-parietal region. A similar anomaly occured in patients in a left- but not right-hand finger-thumb apposition test in left anterior and right posterior regions, and also in a passive visual fixation task where it was located bilaterally in the occipito-parietal region. Functional activation with neuropsychological tests holds promise as one approach to the validation of topographical mapping of brain electrical activity.

Monozygotic Twins with Obsessive-Compulsive Disorder

A mirror-image pair of monozygotic twins concordant for obsessional–compulsive disorder had remarkably similar clinical symptoms, and brain electrical activity mapping showed slower alpha and more theta activity than normal for their age.

Quantified Neurophysiology with mapping: Statistical inference, Exploratory and Confirmatory data analysis

Topographic mapping of brain electrical activity has become a commonly used method in the clinical as well as research laboratory. To enhance analytic power and accuracy, mapping applications often involve statistical paradigms for the detection of abnormality or difference. Because mapping studies involve many measurements and variables, the appearance of a large data dimensionality may be created. If abnormality is sought by statistical mapping procedures and if the many variables are uncorrelated, certain positive findings could be attributable to chance. To protect against this undesirable possibility we advocate the replication of initial findings on independent data sets. Statistical difference attributable to chance will not replicate, whereas real difference will reproduce. Clinical studies must, therefore, provide for repeat measurements and research studies must involve analysis of second populations. Furthermore, Principal Components Analysis can be employed to demonstrate that variables derived from mapping studies are highly intercorrelated and data dimensionality substantially less than the total number of variables initially created. This reduces the likelihood of capitalization on chance. The need to constrain alpha levels is not necessary when dimensionality is low and/or a second data set is available. When only one data set is available in research applications, techniques such as the Bonferroni correction, the "leave-one-out" method, and Descriptive Data Analysis (DDA) are available. These techniques are discussed, clinical and research examples are given, and differences between Exploratory (EDA) and Confirmatory Data Analysis (EDA) are reviewed.

Brain electrical activity mapping (BEAM) of Parkinsonian patients after thalamotomy

Brain electrical activity mapping (BEAM) of Parkinsonian patients after thalamotomy

New solutions to methodological problems in brain electrical activity mapping

New solutions to methodological problems in brain electrical activity mapping

Brain electrical activity mapping of monocular P100 reveals another type of uncrossed asymmetry.

Reference-independent analysis of monocular full-field P100 reveals another type of uncrossed asymmetry, not hitherto appreciated, and perhaps dependent on skull-impedance characteristics.

Brain electrical activity mapping: Clinical applications

The past 5 years have witnessed the growing use of topographic mapping and other quantified techniques in the clinical practice of neurophysiology

Brain electrical activity mapping in different stages of SDAT

We adopted the dynamic Brain Mapping System TM (HZI Research Institute) to study the localization and amount of the four conventional frequency bands, expressed as percentages; in five special programs, distinct accumulations of these frequencies in comparison to age-related healthy person can be seen. We carried out a double-blind study with phosphatidylserine (a drug which may influence membrane fluidity) in a group of 62 Parkinson patients wit SDAT and slowed EEG

Brain Imaging: Applications in Psychiatry

Andreasen's text represents a serious attempt to inform psychiatrists about brain imaging: its technical basis, research findings, and possible clinical applications. We live at a time in which noninvasive tomographic techniques are still in their infancy; however, just as the invention of the microscope revolutionized biology, these new brain mapping techniques will significantly change the face of psychiatry by invalidating certain theories and confirming others. Topics covered include computed tomography (CT); brain electrical activity mapping (BEAM); single-photon emission tomography (SPECT), including studies of regional cerebral blood flow (rCBF); magnetic resonance imaging (MRI); and positron emission tomography (PET). The technical information given about each methodology will be too detailed for some, not detailed enough for others, but is on the whole well written and helps significantly to clarify the advantages and disadvantages of each method. For example, CT and MRI use different principles (x-rays vs magnetic fields) to create anatomic maps

Topographical brain electrical activity mapping on an IBM-compatible personal computer

A new system for computing brain electrical activity maps on a standard IBM-compatible computer has been developed. The EEG is recorded using a CED1401 intelligent laboratory interface and stored in the computer; colour coded maps are generated using softwave developed in Turbo PASCAL and displayed on the EGA graphics screen. An acceptable computation time of 1.2 s for a 64 × 64 map displayed as a 128 × 128 pixel image has been achieved by incorporating assembly language routines and a maths coprocessor. The system may be readily upgraded as improved hardware becomes available and further software can be added. In addition to triggering auditory, visual and somatosensory stimulators, it provides the potential for the generation of complex stimuli for cognitive experiments by means of mass RAM and digital-to-analogue converters.

Brain studies may alter long-held concepts about likely causes of some voice disorders

TWO VOICE DISORDERS long considered to be psychological problems, stuttering and spasmodic dysphonia, have been shown in many persons to have a neurophysiological basis. Investigators at the 155th national meeting of the American Association for the Advancement of Science, in San Francisco, described their findings, which are based on new analytic techniques. The research is being done at the Dallas Center for Vocal Motor Control, Callier Center for Communication Disorders, University of Texas at Dallas Health Science Center. Stuttering affects approximately 1 in 100 persons in the United States, and spasmodic dysphonia, in which spasms of the larynx choke off words as they are uttered, is thought to affect about a tenth as many. The technology employed to learn what's wrong with the brains, rather than the psyches, of persons with certain speech disorders includes magnetic resonance imaging (MRI), brain electrical activity mapping (BEAM), and single photon emission computerized tomography

Brain Studies May Alter Long-Held Concepts About Likely Causes of Some Voice Disorders

TWO VOICE DISORDERS long considered to be psychological problems, stuttering and spasmodic dysphonia, have been shown in many persons to have a neurophysiological basis. Investigators at the 155th national meeting of the American Association for the Advancement of Science, in San Francisco, described their findings, which are based on new analytic techniques. The research is being done at the Dallas Center for Vocal Motor Control, Callier Center for Communication Disorders, University of Texas at Dallas Health Science Center. Stuttering affects approximately 1 in 100 persons in the United States, and spasmodic dysphonia, in which spasms of the larynx choke off words as they are uttered, is thought to affect about a tenth as many. The technology employed to learn what's wrong with the brains, rather than the psyches, of persons with certain speech disorders includes magnetic resonance imaging (MRI), brain electrical activity mapping (BEAM), and single photon emission computerized tomography

An Application of Autoregressive Model to Pattern Discrimination of Brain Electrical Activity Mapping

An Application of Autoregressive Model to Pattern Discrimination of Brain Electrical Activity Mapping

Waves earlier than P3 are more informative in putative subcortical dementias: a study with mapping and neuropsychological techniques.

Thirty subjects (normal controls, patients with putative subcortical dementia and non-demented patient controls) were studied using advanced neurophysiological (16 scalp-electrode positions, computer-assisted brain electrical activity mapping, auditory oddball paradigm) and neuropsychological techniques. Our study suggests that waves earlier than P3 (N1, P2 and N2) are all correlated with global measures of cognitive functions. They are, however, differentially correlated with specific measures of cognitive functions, N1 and P2 with mental speed and N2 with short-term memory. The abnormalities of these waves (earlier than P3) may be an electrophysiologic marker of dementia in patients with putative subcortical states.

Odours, emotion and psychophysiology

Synopsis The basis for the relationship between emotion and olfaction is reviewed and discussed from both the theoretical and experimental approach. Published studies include olfactory memory, human semiochemicals, and olfactory communication between humans. Evidence for the olfactory system being a special emotion sense has not been conclusive. One limitation has been the verbal paucity of subjects in describing smells. This has led to the development of psychophysiological techniques involving the use of subvert bioelectrical signals generated within the body. A number of techniques involving measurement of the electrical activity of the brain are discussed. These involve evoked olfactory potentials (OEP), contingent negative voltage (CNV) and brain electrical activity mapping (BEAM). These new techniques involving the electrical activity of the cortex are helping us to unravel the complexities of olfaction and emotion.

Topographic maps of brain electrical activity-pitfalls and precautions

Topographic mapping of brain electrical activity is a popular, powerful, and potentially misleading technique. The map lies at the end of a long chain of physiological, technical, electronic, and mathematical processes and is vulnerable to artifact, error, and distortion at many points. Close attention must be paid to data collection parameters, subject cooperation, minimization of artifact, limitations of resolutions, selection, and transformation of parameters for display, and map generation strategy to yield an accurate, physiologically interpretable map. Review of the data at each step of analysis, from the paper electroencephalogram (EEG) to sets of maps on video display, may be necessary for optimum understanding. Development of more sophisticated qualitative and quantitative concepts of “normal” physiology is needed. These improvements in electrophys-iological data analysis demand, rather than obviate, sophistication on the part of the user.