Abstract: An averaging method for elimination of periodic stray signals, such as stray signals originating ain an environment (2) comprising a main signal source, which method is employed in a system for measuring evoked responses during an averaging procedure run in an averaging computer (7) which processes a set of signals picked up from an examined subject (10), e.g. a human scalp, by means of electrodes (11) which set of signals is fed through an instrumentat ion amplifier (9) to an averaging computer (7). A counting circuit in the system for measuring evoked responses comprises a sensing circuit (1), a circuit (3) detecting signal half-periods, a counting circuit (5) and a triggering circuit (6), and introduces permanent desynchronization between the frequency 1/T of external stimuli signals, e.g.

Abstract: An electrophysiological photostimulator, particularly to study evoked visual potentials, comprises a luminescent matrix source, its surface having unit sources arranged in order under a control unit. The control photostimulator in the control unit has function, shape and form programmers, which control the stimulation source that is the luminescence matrix through an adder with a steady luminance level unit and a system for switching over the y and y lines and lighting up systems. The shape and form programmers solve the problem of dynamic stimuli understood as successive alternations of shape during one stimulus T. The described photostimulator facilitates the examinations in the field of electroencephalography, electroretinography, electronstagmography and electroocculography.