The invention is directed to an apparatus for finding a functional tissue area in a tissue region. The apparatus has a measurement illuminating device suitable for emitting measurement illumination to the tissue region and a camera which can capture light reflected by the tissue region. The camera has a green channel and/or a blue channel wherein there is a change in an optical property of the light reflected by the tissue region during the stimulation thereof which is undertaken at least intermittently. An evaluation unit captures the change in the optical property only by a signal of the green channel and/or of the blue channel of the camera. A display unit can display an output signal of the evaluation unit for the functional tissue area in the tissue region.
