For measurement and display of auditory evoked potentials of the brain, pickup electrodes (A, Ref), an amplifier circuit (1 . . . 5) and an evaluation facility (7) are used to display the time trend of midlatency auditory evoked potentials (MLAEP) and simultaneously therewith, during measurement of the information signals, the time trend of early brain stem auditory evoked potentials (BAEP), which is displayed at a higher time resolution as compared to the information curve. For this purpose an amplifier circuit is used the isolation stage (8) of which is arranged in a way so that the total gain of the amplifier unit (1, 3) connected between electrode assembly (A, Ref) and isolation stage (8) amounts to between approximately 1000 and 4000. A further improvement is achieved by connecting the inputs of the amplifier circuits, which are connected to one pick up electrode (A, Ref) each and to a reference potential (ground) via an input terminating resistor, to a current generator included in an impedance measuring circuit for measuring electrode impedance.
Method and apparatus for measuring stimulus-evoked potentials of the brain