[Cerebral potentials related to visual stimulation. Pattern inversion and flash]

Distinguishing between electroencephalogram (EEG) and event-related potentials (ERP) as indicators of brain electrical activity, methodological considerations pertaining to the recording of ERP to visual stimulation (evoked potentials, EP) are presented. Visual EP may be either steady-state or transient, depending upon stimulation used (repetitive versus transient) and method of analysis (frequency domain versus time domain). While both have diagnostic applications, this paper concentrates on transient visual EP. Based on the contention that intra and interindividual EP variability is the single most important issue in clinical practice, it presents data comparing two widely employed techniques (checkerboard reversal and flash stimulation) with respect to their stability in normal populations and their diagnostic sensitivity in demyelinating disease.