Age-related features of the resting and P300 auditory evoked responses using the dipole localization method and cortical imaging technique.

Two mathematical techniques, the dipole localization method (DLM) and the cortical imaging technique (CIT), are used to analyze the resting and P300 auditory responses in young and old normal volunteers. These methods identify certain age-related features of these evoked responses that are not found by standard topographic methods. These features include the orientation of the P200 resting response, and the laterality of the N120 response, and the eccentricity of the P300 response in the P300 stimulus condition. Theoretical dipole sources and simulated cortical surface maps are also constructed for one normal subject and one psychiatric inpatient and compared. These mathematical methods appear to enhance the discriminating power of traditional electrophysiological measures.