Repeatability of the intensity dependence of cortical auditory evoked potentials in the assessment of cortical information processing

Data on repeatability and optimal settings are needed when studying the inf luence of drugs on the intensity dependence of auditory evoked cortical pot entials (IDAP). IDAP was recorded at intervals of 1, 2, and 24 h at two cen ters in 22 healthy volunteers. Settings were modified to compare fixed vers us randomly varied stimulus repetition rate, as well as 30 Hz and 100 Hz lo w pass filters. Repeatability was assessed for different intervals and diff erent settings. Group means did not differ between centers, the 2-h or 24-h retest, or when using different settings. We observed an order effect for the 1 h retest. Fixed repetition rate and the 30 Hz filter improved repeata bility with still high intraindividual variability. IDAP group means can be compared between centers for retest intervals of 2 h and 24 h and differen t settings. Variability is too large to compare individuals.