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Source estimation of surface laplacian transformed EEG potentials on a talairach-based source space
NemoImage
13, Number
6, 2001, Part 2 of 2 Parts 1 D E a[@
METHODS
- ANALYSIS
Source estimation of surface Laplacian transformed EEG potentials on a Talairach-based source space. Febo Cincotti*t, Filippo Carducci*$, Claudio Babiloni*& Paolo Maria RossiniS, Fabio Babiloni* *Dip. Fisiologia Umana e Farmacologia,
Universid
“IA Sapienza”, Rome, Italy
TIRCCS Fondazione Santa Lucia, Rome, Italy $IRCCS Ospedale “S. Giovanni di Dio” - Fatebenefratelli, Brescia, Italy $CRCCS Ospedale “S. Giovanni Calabita ” - Fatebenefratelli, Isola Tiberina, Rome, Italy We propose a high resolution electroencephalographic (EEG) procedure including high spatial sampling (128 channels), magnetic resonance-constructed head model, multi-dipole cortical source model, and regularized Weighted Minimum-Norm linear inverse source estimation (WMN). EEG potentials are preliminarily Laplacian-Transformed (LT) to remove brain electrical activity generated by subcortical sources. (i.e. not represented into the source model). LT-WMN estimates are mathematically evaluated by figures of merit (WMN estimates as a reference). Structures of interest of head volume conductor were segmented and tessellated; about 1000 triangles for each structure were used for scalp, skull and dura mater, while the distributed source space was obtained by tessellating the cortical space with about 6000 triangles, and placing an equivalent current dipole at the vertex of each triangle (3-4000 dipoles). The procedure is tested on short latency Somatosensory Evoked Potentials Besides the highly-dimensional solutions obtained considering each dipole separately, WMN and LT-WMN solutions were also collapsed within regions of the cortical model corresponding to regions of interest (ROIs), thus providing time evolution of activity at those regions. Such ROIs were segmented at cortical areas (prefrontal, premotor, primary sensorimotor, posterior-parietal). which are known to be involved in motor and cognitive tasks. The ROIs were drawn based on landmarks of cortical mantle and Talairach coordinates information. Results show an increased spatial information content in LT-WMN than WMN estimates, as revealed by higher Dipole Identifiability, lower Dipole Localization Error, and lower Spatial Dispersion in LT-WMN than WMN estimates, The availability of results referred to Talairach’s space helps to compare results from different subjects. In conclusion, the proposed technique benefits from the enhancement of the EEG source linear inverse estimators and is helpful when performing comparative or group studies.
s97
13, Number
6, 2001, Part 2 of 2 Parts 1 D E a[@
METHODS
- ANALYSIS
Source estimation of surface Laplacian transformed EEG potentials on a Talairach-based source space. Febo Cincotti*t, Filippo Carducci*$, Claudio Babiloni*& Paolo Maria RossiniS, Fabio Babiloni* *Dip. Fisiologia Umana e Farmacologia,
Universid
“IA Sapienza”, Rome, Italy
TIRCCS Fondazione Santa Lucia, Rome, Italy $IRCCS Ospedale “S. Giovanni di Dio” - Fatebenefratelli, Brescia, Italy $CRCCS Ospedale “S. Giovanni Calabita ” - Fatebenefratelli, Isola Tiberina, Rome, Italy We propose a high resolution electroencephalographic (EEG) procedure including high spatial sampling (128 channels), magnetic resonance-constructed head model, multi-dipole cortical source model, and regularized Weighted Minimum-Norm linear inverse source estimation (WMN). EEG potentials are preliminarily Laplacian-Transformed (LT) to remove brain electrical activity generated by subcortical sources. (i.e. not represented into the source model). LT-WMN estimates are mathematically evaluated by figures of merit (WMN estimates as a reference). Structures of interest of head volume conductor were segmented and tessellated; about 1000 triangles for each structure were used for scalp, skull and dura mater, while the distributed source space was obtained by tessellating the cortical space with about 6000 triangles, and placing an equivalent current dipole at the vertex of each triangle (3-4000 dipoles). The procedure is tested on short latency Somatosensory Evoked Potentials Besides the highly-dimensional solutions obtained considering each dipole separately, WMN and LT-WMN solutions were also collapsed within regions of the cortical model corresponding to regions of interest (ROIs), thus providing time evolution of activity at those regions. Such ROIs were segmented at cortical areas (prefrontal, premotor, primary sensorimotor, posterior-parietal). which are known to be involved in motor and cognitive tasks. The ROIs were drawn based on landmarks of cortical mantle and Talairach coordinates information. Results show an increased spatial information content in LT-WMN than WMN estimates, as revealed by higher Dipole Identifiability, lower Dipole Localization Error, and lower Spatial Dispersion in LT-WMN than WMN estimates, The availability of results referred to Talairach’s space helps to compare results from different subjects. In conclusion, the proposed technique benefits from the enhancement of the EEG source linear inverse estimators and is helpful when performing comparative or group studies.
s97