The invention relates to a method for obtaining brain wave data using a microelectrode array, comprising a plurality of electrodes for electrically measuring brain waves and an integrated optical stimulation unit for stimulating brain regions by means of optical signals, wherein the stimulation unit has one or more electrical light sources, and wherein the method includes stimulating neurons of the brain via optical signals produced by the light sources, recording a response of the neurons to the stimulation via the electrodes, unambiguously assigning the recorded response to individual optical stimulation signals provided by the light source, and determining an unambiguous correlation between the optical stimulation signals and resulting brain waves measured by the electrodes.