A method and device are for generating and displaying a map of a brain operating field, brain tissue areas associated with a stimulated brain function being marked in the map. In the method, during a measurement cycle a stimulation of a brain function is effected and a stimulation image of the brain operating field with the stimulated brain function is recorded, a reference image without the stimulated brain function is recorded, the stimulation image and the reference image are used to generate the map, and the map is displayed on a display. A plurality of cycles are performed. A new map is generated after each cycle following the first cycle. In order to generate the new map, the stimulation and reference images of one or more preceding cycles are used besides the images recorded in the cycle just carried out. At least the new map is displayed after each cycle.