Abstract: An arrangement is disclosed for carrying out electrode measurements on the surface of the skin of a patient's head for recording the electrical activity of the brain, the arrangement including a matrix electrode configuration, which includes a body part of non-conductive material conforming to the contours of the surface of the skin. The arrangement includes electrodes for producing the measurement data connected to the body part, means for transmitting the measurement data connected to the body part, and a measurement data unit for receiving the measurement data transmitted by the means for further processing of the measurement data. The body part can include an electrode placement configuration for maintaining the mutual placements of the electrodes with respect to one another and an active attachment surface located between the electrodes and the surface of the skin to produce measurement data.