THE SPATIAL LOCATION OF EEG ELECTRODES - LOCATING THE BEST-FITTING SPHERE RELATIVE TO CORTICAL ANATOMY


TOWLE V., BOLANOS J., SUAREZ D., TAN K., GRZESZCZUK R., LEVIN D., ...More

ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY, no.1, pp.1-6, 1993 (SCI-Expanded) identifier identifier identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 1993
  • Doi Number: 10.1016/0013-4694(93)90061-y
  • Journal Name: ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED)
  • Page Numbers: pp.1-6
  • Keywords: EVOKED POTENTIALS (EP), EEG DIPOLE LOCALIZATION METHODS (DLM), 10-20 SYSTEM, BRAIN FUNCTION, BRAIN, SYSTEM, IMAGES, PET, LOCALIZATION, PLACEMENT, CORTEX, CT, MR
  • Dokuz Eylül University Affiliated: Yes

Abstract

The location of the international 10-20 system electrode positions and 14 fiducial landmarks are described in cartesian coordinates (+/- 1.4 mm average accuracy). Six replications were obtained on 3 separate days from 4 normal subjects, who were compared to each other with a best-fit sphere algorithm. Test-retest reliability depended on the electrode position: the parasagittal electrodes were associated with greater measurement errors (maximum 7 mm) than midline locations. Location variability due to head shape was greatest in the temporal region, averaging 5 mm from the mean. For each subject's electrode locations a best-fitting sphere was determined (79-87 mm radius, 6% average error). A surface-fitting algorithm was used to transfer the electrode locations and best-fitting sphere to MR images of the brain and scalp. The center of the best-fitting sphere coincided with the floor of the third ventricle 5 mm anterior to the posterior commissure. The melding of EEG electrode location information with brain anatomy provides an empirical basis for associating hypothetical equivalent dipole locations with their anatomical substrates.