Conductivity ratios of the scalp-skull-brain head model in estimating equivalent dipole sources in human brain

Homma, S.; Musha, Toshimitsu; Nakajima, Yoshio; Okamoto, Yoshiwo; Blom, S; Flink, Roland; Hagbarth, K.‐E.

doi:10.1016/0168-0102(95)00880-3

Cited by 60 publications

(46 citation statements)

References 13 publications

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“…We analyzed selected interictal spikes and calculated ECDs using a single dipole method and a realistic three-shell head model with inhomogeneous electrical conductivity (i.e. 1, 1/80 and 1 for scalp, bone and brain, respectively) [1,2]. To minimize the localization error, we set the threshold of dipolarity above 0.98 [1,2].…”

Section: Methodsmentioning

confidence: 99%

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Usefulness of the Dipole Tracing Method with a Scalp-Skull-Brain Head Model: Relationship between the Epileptic Focus and Equivalent Current Dipole Locations

Chitoku

Hoshida²,

Hirabayashi³

et al. 1999

Stereotact Funct Neurosurg

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Purpose: We examined whether the dipole tracing (DT) method with a realistic three-shell head model and inhomogeneous electric conductivity is useful to estimate the epileptic focus from interictal spikes. Method: This study included 17 temporal lobe epilepsy (TLE) cases, classified into three types as type A (unilateral), type B (intermediate) and type C (bilateral) and 5 extratemporal epilepsy (XTLE) cases. The epileptic areas were determined by noninvasive and/or invasive examinations. Selected interictal spikes were analyzed and the calculated equivalent current dipoles (ECDs) of dipolarity greater than 0.98 were superimposed over the realistic head model in each patient. We evaluated the ECD concentration within and around the epileptic area. Results: In TLE cases, types A showed better ECD concentration (87%) within the epileptic area than other types (type B: 68%; type C: 74%). XTLE exhibited variable ECD distribution within and around the epileptic area. Conclusion: The DT method with a realistic head model and inhomogeneous electric conductivity can be useful to estimate the epileptic area from interictal spikes, especially in unilateral TLE cases.

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Section: Methodsmentioning

confidence: 99%

“…1, 1/80 and 1 for scalp, bone and brain, respectively) [1,2]. To minimize the localization error, we set the threshold of dipolarity above 0.98 [1,2]. Invasive recording was performed in 15 cases to determine more precisely the epileptogenic area as well as normal cortical function.…”

Section: Methodsmentioning

confidence: 99%

Usefulness of the Dipole Tracing Method with a Scalp-Skull-Brain Head Model: Relationship between the Epileptic Focus and Equivalent Current Dipole Locations

Chitoku

Hoshida²,

Hirabayashi³

et al. 1999

Stereotact Funct Neurosurg

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“…The minimum (d) was calculated by changing the approximated location of the dipole. When the minimum was obtained, the location thus determined was regarded as a "real" location of the current dipole to produce the measured potentials [2,[5][6][7]. Even though the minimum was thus obtained, error from residue was still a possibility.…”

mentioning

confidence: 99%

“…In the first step, the SSB/DT method was used to approximate one dipole for the currently interested wave in the brain [2,[5][6][7]. Then the potentials produced for 21 electrodes on the scalp from the approximated dipole were calculated.…”

mentioning

confidence: 99%

Generator Sources of EEG Large Waves Elicited by Mental Stress of Memory Recall or Mental Calculation.

Matsunami¹,

Homma²,

Han³

et al. 2001

JJP

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“…To reduce these sources of error a realistic head-shape model can be constructed from computed tomography (CT) or MRI head scan images. The internal structures of the head are represented in different chambers and the model solutions are solved by using the boundary element method (BEM) [8], [9]. Another type of model utilizes the finite element method (FEM) [10], [11] which allows more complex internal geometry and tissue conductivity features to be included, and is more precise.…”

mentioning

confidence: 99%

The forward EEG solutions can be computed using artificial neural networks

Sun

Sclabassi

2000

IEEE Trans. Biomed. Eng.

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Abstract-Study of electroencenphalogarphy (EEG) is the one of the most utilized methods in both basic brain research and clinical diagnosis of neurological disorders. Recent technological advances in computer and electronic systems have allowed the EEG to be recorded from large electrode arrays. Modeling the brain waves using a head volume conductor model provides an effective method to localize functional generators within the brain. However, the forward solutions to this model, which represent theoretical potentials in response to current sources within the volume conductor, are difficult to compute because of time-consuming numerical procedures utilized in either the boundary element method (BEM) or the finite element method (FEM). This paper presents a novel computational approach using an artificial neural network (ANN) to map two vectors of forward solutions. These two vectors correspond to different head models but with respect to the same current source. The input vector to the ANN is based on the spherical head model, which can be computed efficiently but involves large errors. The output vector from the ANN is based on the spheroidal model, which is more precise, but difficult to compute directly using the traditional means. Our experiments indicate that this ANN approach provides a remarkable improvement over the BEM and FEM methods: 1) the mean-square error of computation was only approximately 0.3% compared to the exact solution; 2) the online computation was extremely efficient, requiring only 168 floating point operations per channel to compute the forward solution, and 10.2 K-bytes of storage to represent the entire ANN. Using this approach it is possible to perform real-time EEG modeling accurately on personal computers.

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Conductivity ratios of the scalp-skull-brain head model in estimating equivalent dipole sources in human brain

Cited by 60 publications

References 13 publications

Usefulness of the Dipole Tracing Method with a Scalp-Skull-Brain Head Model: Relationship between the Epileptic Focus and Equivalent Current Dipole Locations

Usefulness of the Dipole Tracing Method with a Scalp-Skull-Brain Head Model: Relationship between the Epileptic Focus and Equivalent Current Dipole Locations

Generator Sources of EEG Large Waves Elicited by Mental Stress of Memory Recall or Mental Calculation.

The forward EEG solutions can be computed using artificial neural networks

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