Bit-mapped color imaging of human evoked potentials with reference to the N20, P22, P27 and N30 somatosensory responsesComment réaliser l'imagerie digitale des potentiels évoqués chez l'homme☆

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Abstract

Bit-mapped color imaging of scalp potential fields evoked by sensory stimulation in humans disclosed significant features not indentified by mere inspection of multichannel traces. Methodological problems are considered in detail for early cortical SEPs which include several components with sharp rise times occurring at spatially distinct scalp locations. A manageable yet efficient imaging system requires recording electrodes in adequate number and scalp locations, bandpass fidelity to resolve slow and fast components, consistency of bioelectric input data, optimal interpolation and mapping algorithms, and consistent color scaling. Critical steps in these procedures were investigated in conjunction with new evidence on the scalp topography and neural generators of the N20, P20, P22, P27 and N30 SEP components. It is concluded that N20-P20 reflect a tangential equivalent dipole in parietal area 3b while P22 reflects a radial equivalent dipole in motor area 4.

Résumé

L'imagerie digitale des champs de potentiels cérébraux évoqués par stimulation sensorielle chez l'homme met en évidence des faits qui ne sont pas évidents lors de l'observation des tracés multicanaux. On considère en détail les problèmes de méthodes pour les potentiels somesthésiques qui comportent beaucoup de composantes rapides à localisations distinctes.

Un système d'imagerie efficace nécessite un nombre suffisant d'électrodes en des endroits critiques du cuir chevelu, une bande passante résolvant les composantes rapides, des logiciels et des échelles de couleurs appropriés. Les points critiques de ces méthodes ont été analysés et discutiés.

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    ☆

    This research was supported by the Fonds de la Recherche Scientifique Médicale, Belgium.

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