A monitoring assembly comprises probes (1, 4) for inserting into a body, the first probe (1) being coupled to at least one light source (8) or acoustic source in order to generate a stimulation signal and the second probe (4) being arranged in order to detect a response signal of a target organ. The stimulation signal is suitable for differentiating between neuronal tissue and non-neuronal tissue, whereas the response signal is detected as an EMG signal or pressure signal. The two probes are connected to a monitoring computer (15) via control- (9, 13) and evaluation devices (10, 14).