Cerebral location of international 10-20 system electrode placement.

We employed CT scanning to correlate scalp markers placed according to the international 10-20 system with underlying cerebral structures. Subjects were 12 normal volunteers. Measurements included assessment for cranial asymmetry to determine the effect of skull asymmetry on cortical location of electrodes. Results were correlated with the cortical histological map of Brodmann. Primary cortical locations agree well with previously published data and provide cortical localization in greater detail than previous studies. Variability of cortical electrode location was substantial in some cases and not related to cranial asymmetry. The results indicate that CT scanning or other neuroimaging techniques which reveal detailed cerebral anatomy would be potentially highly useful in defining the generators of electrocerebral potentials recorded from the scalp.