Relationship of the magnetoencephalogram to the electroencephalogram. Normal wake and sleep activity

Hughes, John R.; Hendrix, D. E.; Cohen, Jerome; Duffy, Frank H.; Mayman, Chaim I.; Scholl, Mary Louise; Cuffin, B. Neil

doi:10.1016/0013-4694(76)90150-4

Cited by 54 publications

(11 citation statements)

References 12 publications

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“…Previous reports have shown that some spindles are recorded by MEG but not EEG, and vice versa [17], [20], [21], [22], and that intracranially recorded spindles often have no clear or consistent relationship to the spindles recorded simultaneously at the scalp [46], [47], [48], [52]. These observations would also be consistent with the view that MEG and EEG are recording from different brain systems during spindles.…”

Section: Discussionsupporting

confidence: 83%

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Divergent Cortical Generators of MEG and EEG during Human Sleep Spindles Suggested by Distributed Source Modeling

et al. 2010

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BackgroundSleep spindles are ∼1-second bursts of 10–15 Hz activity, occurring during normal stage 2 sleep. In animals, sleep spindles can be synchronous across multiple cortical and thalamic locations, suggesting a distributed stable phase-locked generating system. The high synchrony of spindles across scalp EEG sites suggests that this may also be true in humans. However, prior MEG studies suggest multiple and varying generators.Methodology/Principal FindingsWe recorded 306 channels of MEG simultaneously with 60 channels of EEG during naturally occurring spindles of stage 2 sleep in 7 healthy subjects. High-resolution structural MRI was obtained in each subject, to define the shells for a boundary element forward solution and to reconstruct the cortex providing the solution space for a noise-normalized minimum norm source estimation procedure. Integrated across the entire duration of all spindles, sources estimated from EEG and MEG are similar, diffuse and widespread, including all lobes from both hemispheres. However, the locations, phase and amplitude of sources simultaneously estimated from MEG versus EEG are highly distinct during the same spindles. Specifically, the sources estimated from EEG are highly synchronous across the cortex, whereas those from MEG rapidly shift in phase, hemisphere, and the location within the hemisphere.Conclusions/SignificanceThe heterogeneity of MEG sources implies that multiple generators are active during human sleep spindles. If the source modeling is correct, then EEG spindles are generated by a different, diffusely synchronous system. Animal studies have identified two thalamo-cortical systems, core and matrix, that produce focal or diffuse activation and thus could underlie MEG and EEG spindles, respectively. Alternatively, EEG spindles could reflect overlap at the sensors of the same sources as are seen from the MEG. Although our results generally match human intracranial recordings, additional improvements are possible and simultaneous intra- and extra-cranial measures are needed to test their accuracy.

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Section: Discussionsupporting

confidence: 83%

“…Further evidence against a monolithic distributed synchronous generator has been found in comparisons of simultaneous EEG and MEG (magnetoencephalogram) recordings during spindles. Spindles may appear only in the MEG, only EEG, or in both modalities [15], [17], [20], [21], [22] …”

Section: Introductionmentioning

confidence: 99%

Divergent Cortical Generators of MEG and EEG during Human Sleep Spindles Suggested by Distributed Source Modeling

et al. 2010

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“…In simultaneous EEG/MEG recordings, spindle activity was sometimes detected in one of the modalities only (Hughes et al, 1976; Manshanden et al , 2002; Nakasato et al , 1990; Yoshida et al , 1996, Dehghani et al ., 2010b). Recently, Dehghani et al .…”

Section: Discussionmentioning

confidence: 99%

Interactions between Core and Matrix Thalamocortical Projections in Human Sleep Spindle Synchronization

Bonjean

Baker²,

Bazhenov³

et al. 2012

J. Neurosci.

100

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Sleep spindles, which are bursts of 11–15 Hz that occur during non-REM sleep, are highly synchronous across the scalp when measured with EEG, but have low spatial coherence and exhibit low correlation with EEG signals when simultaneously measured with MEG spindles in humans. We developed a computational model to explore the hypothesis that the spatial coherence of the EEG spindle is a consequence of diffuse matrix projections of the thalamus to layer 1 compared to the focal projections of the core pathway to layer 4 recorded by the MEG. Increasing the fanout of thalamocortical connectivity in the matrix pathway while keeping the core pathway fixed led to increased synchrony of the spindle activity in the superficial cortical layers in the model. In agreement with cortical recordings, the latency for spindles to spread from the core to the matrix was independent of the thalamocortical fanout but highly dependent on the probability of connections between cortical areas.

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“…An early study noted that MEG spindles can be completely absent even when the EEG spindle is clear [Hughes et al, 1976]. A later single-sensor study found that MEG spindles were more common but occurred only at vertex [Nakasato et al, 1990].…”

Section: Introductionmentioning

confidence: 99%

Emergence of synchronous EEG spindles from asynchronous MEG spindles

Dehghani¹,

Cash²,

Halgren³

2011

Human Brain Mapping

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Sleep spindles are bursts of rhythmic 10–15 Hz activity, lasting ~0.5–2 s, that occur during Stage 2 sleep. They are coherent across multiple cortical and thalamic locations in animals, and across scalp EEG sites in humans, suggesting simultaneous generation across the cortical mantle. However, reports of MEG spindles occurring without EEG spindles, and vice versa, are inconsistent with synchronous distributed generation. We objectively determined the frequency of MEG-only, EEG-only, and combined MEG-EEG spindles in high density recordings of natural sleep in humans. About 50% of MEG spindles occur without EEG spindles, but the converse is rare (~15%). Compared to spindles that occur in MEG only, those that occur in both MEG and EEG have ~1% more MEG coherence and ~15% more MEG power, insufficient to account for the ~55% increase in EEG power. However, these combined spindles involve ~66% more MEG channels, especially over frontocentral cortex. Furthermore, when both MEG and EEG are involved in a given spindle, the MEG spindle begins ~150 ms before the EEG spindle and ends ~250 ms after. Our findings suggest that spindles begin in focal cortical locations which are better recorded with MEG gradiometers than referential EEG due to the biophysics of their propagation. For some spindles, only these regions remain active. For other spindles, these locations may recruit other areas over the next 200 ms, until a critical mass is achieved, including especially frontal cortex, resulting in activation of a diffuse and/or multifocal generator that is best recorded by referential EEG derivations due to their larger leadfields.

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Relationship of the magnetoencephalogram to the electroencephalogram. Normal wake and sleep activity

Cited by 54 publications

References 12 publications

Divergent Cortical Generators of MEG and EEG during Human Sleep Spindles Suggested by Distributed Source Modeling

Divergent Cortical Generators of MEG and EEG during Human Sleep Spindles Suggested by Distributed Source Modeling

Interactions between Core and Matrix Thalamocortical Projections in Human Sleep Spindle Synchronization

Emergence of synchronous EEG spindles from asynchronous MEG spindles

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