The scalp as an electroencephalographic averager

DeLucchi, M. R.; Garoutte, Bill; Aird, Robert B.

doi:10.1016/0013-4694(62)90028-7

Cited by 98 publications

(36 citation statements)

References 9 publications

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“…Recordable surface potentials (cortex or scalp) require sufficient modulation depth of synaptic action, which can be measured as relatively large potential differences between deep and superficial cortex, e.g., several hundred microvolts [Lopes da Silva and Storm van Leeuwen, 1978;Petsche et al, 1984]. Recordable scalp potentials also require substantial source activity at low spatial frequencies, i.e., the sources must be "synchronously active" at scales of at least several centimeters [Cooper et al, 1965;Delucchi et al, 1975;Nunez, 1981;Ebersole, 1997]. Amplitude spectra based on 5 min of resting EEG (0.2 Hz resolution) with eyes closed, referenced to the (symmetric) digitally averaged potential of the ears.…”

Section: Synaptic Action Is Imperfectly Related To Measured Potentialsmentioning

confidence: 99%

Spatial‐temporal structures of human alpha rhythms: Theory, microcurrent sources, multiscale measurements, and global binding of local networks

Nunez¹,

Wingeier²,

Silberstein³

2001

Human Brain Mapping

470

356

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A theoretical framework supporting experimental measures of dynamic properties of human EEG is proposed with emphasis on distinct alpha rhythms. Robust relationships between measured dynamics and cognitive or behavioral conditions are reviewed, and proposed physiological bases for EEG at cellular levels are considered. Classical EEG data are interpreted in the context of a conceptual framework that distinguishes between locally and globally dominated dynamic processes, as estimated with coherence or other measures of phase synchronization. Macroscopic (scalp) potentials generated by cortical current sources are described at three spatial scales, taking advantage of the columnar structure of neocortex. New EEG data demonstrate that both globally coherent and locally dominated behavior can occur within the alpha band, depending on narrow band frequency, spatial measurement scale, and brain state. Quasi-stable alpha phase structures consistent with global standing waves are observed. At the same time, alpha and theta phase locking between cortical regions during mental calculations is demonstrated, consistent with neural network formation. The brain-binding problem is considered in the context of EEG dynamic behavior that generally exhibits both of these local and global aspects. But specific experimental designs and data analysis methods may severely bias physiological interpretations in either local or global directions.

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Section: Synaptic Action Is Imperfectly Related To Measured Potentialsmentioning

confidence: 99%

Spatial‐temporal structures of human alpha rhythms: Theory, microcurrent sources, multiscale measurements, and global binding of local networks

Nunez¹,

Wingeier²,

Silberstein³

2001

Human Brain Mapping

470

356

View full text Add to dashboard Cite

show abstract

“…In addition, the sensitivity pattern of MEG decreases more rapidly with source depth than that of EEG (Cuffin and Cohen, 1979). Finally, the high resistivity of the skull in combination with the more conductive scalp smears and attenuates the electrical potential distribution (Cooper et al, 1965;Delucchi et al, 1962;Geisler and Gerstein, 1961), whereas it does not affect the magnetic fields (Grynszpan and Geselowitz, 1973); this confers a localization advantage for MEG, for those sources that it is able to detect (Cuffin and Cohen, 1979).…”

Section: Introductionmentioning

confidence: 99%

The advantage of combining MEG and EEG: Comparison to fMRI in focally stimulated visual cortex

et al. 2007

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To exploit the high (millisecond) temporal resolution of magnetoencephalography (MEG) and electroencephalography (EEG) for measuring neuronal dynamics within well-defined brain regions, it is important to quantitatively assess their localizing ability. Previous modeling studies and empirical data suggest that a combination of MEG and EEG signals should yield the most accurate localization, due to their complementary sensitivities. However, these two modalities have rarely been explicitly combined for source estimation in studies of recorded brain activity, and a quantitative empirical assessment of their abilities, combined and separate, is currently lacking. Here we studied early visual responses to focal Gabor patches flashed during subject fixation. MEG and EEG data were collected simultaneously, and compared with the functional MRI (fMRI) localization produced by identical stimuli, in the same subjects. This allowed direct evaluation of the localization accuracy of separate and combined MEG/EEG inverse solutions. We found that the localization accuracy of the combined MEG+EEG solution was consistently better than that of either modality alone, using three different source estimation approaches. Further analysis suggests that this improved localization is due to the different properties of the two imaging modalities, rather than simply due to increased total channel number. Thus, combining MEG and EEG data is important for highresolution spatiotemporal studies of the human brain.

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“…Alpha recorded in the EEG is not functionally equivalent to postsynaptic potentials of the same period, for example. Since there are fundamental signal sources for alpha in the cortex at the synaptic level and there are phase, frequency, and amplitude differences between "cortical columns" not larger than .5 mm in diam (Andersen & Andersson, 1968), thousands of different alphas with different frequencies, amplitudes, and phase relations occur simultaneously beneath a single surface electrode and are averaged through the scalp as the EEG, a highly processed signal formed through the process of entrainment and averaging (Delucchi, Garoute, & Aird, 1962;Dewan, 1969;Perez-Borja, 1962). Andersen and Andersson (I968) proposed that these signal generators are entrained by individual cell groups within the thalamus which as a whole acts as a master pacemaker among all the facultative pacemakers.…”

Section: Discussionmentioning

confidence: 99%

EEG alpha entrainment reaction within the biofeedback setting and some possible effects on epilepsy

1975

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Twenty-four human volunteers were given one 30-min EEG alpha biofeedback training session within an active placebo setting. Ten dependent measures computed from serial 3-min period distributions showed no difference between contingent and yoke conditions or between 9-11 and 8-13 Hz feedback. Most subjects showed entrainment of the alpha rhythm toward a stable frequency over trials. Five additional subjects given five daily 30-min sessions of 9 .5-10.5 Hz feedback showed a repetition of this same effect. Over a period of 4 months, one grand mal epileptic gradually entrained a bimodal period distribution toward a unimodal one centered at 10 Hz. This effect was paralleled by a significant drop in seizure rate. These results were interpreted in terms of electro physiological homeostasis.Several experiments have reported that human subjects have used information provided by an EEG alpha/no·alpha biofeedback loop (Mulholland & Runnals, 1961) to manipulate the occurrence of alpha waves (8-13 Hz) vs little or no alpha

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The scalp as an electroencephalographic averager

Cited by 98 publications

References 9 publications

Spatial‐temporal structures of human alpha rhythms: Theory, microcurrent sources, multiscale measurements, and global binding of local networks

Spatial‐temporal structures of human alpha rhythms: Theory, microcurrent sources, multiscale measurements, and global binding of local networks

The advantage of combining MEG and EEG: Comparison to fMRI in focally stimulated visual cortex

EEG alpha entrainment reaction within the biofeedback setting and some possible effects on epilepsy

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