Spatial localization of EEG electrodes.
OBJECTIVE
An important goal for EEG-based functional brain studies is to estimate the location of brain sources that produce the scalp-recorded signals. Such source localization requires locating precisely the position of the EEG sensors. This review describes and compares different methods that are used for localizing EEG sensors.


RESULTS
Five different methods have been described in literature. Manual methods consist in manual measurements to calculate the 3D coordinates of the sensors. Electromagnetic and ultrasound digitization permit localization by using trade devices. The photogrammetry system consists in taking pictures of the patient's head with the sensors. The last method consists in directly localizing the EEG sensors in the MRI volume.


CONCLUSIONS
The spatial localization of EEG sensors is an important step in performing source localization. This method should be accurate, fast, reproducible, and cheap. Currently, electromagnetic digitization is the most currently used method but MRI localization could be an interesting way because no additional method or device needs to be used to locate the EEG sensors.
Koessler
L
L
Inserm ERI13, University Henri Poincaré, 54000 Nancy, France.
Maillard
L
L
Benhadid
A
A
Vignal
J-P
JP
Braun
M
M
Vespignani
H
H
D000465:Algorithms; D004566:Electrodes; D004569:Electroencephalography / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D012535:Scalp / Q000033:anatomy & histology; D017585:Ultrasonography, Doppler, Transcranial