J.P.C. de Weerd Evoked potentials are the electrical voltage fluctuations which can be recorded from parts of the nervous system in response to stimulation of sensory modalities. One may distinguish between evoked
potentials from the peripheral and the central nervous system. For the latter type a further subdivision can be made into spinal, brainstem, and cortical evoked potentials, according to the (assumed) structures from which the
responses derive. Another possible subdivision can be made with respect to the specific sensory ffiodality which is stimulated. Accordingly, one has auditory, somatosensory, visual, gustatory and olfactory evoked potentials.
At the present time, the former three types of evoked potentials are the ones that are commonly measured in diagnostic procedures. Yhe corresponding sensory systems are relatively easy to stimulate, for example by means of an
acoustic click, abrief electrical shock or a reversing light pattern. In contrast, stimulation of the olfactory and gustatory systems has proven to be technically and physiologically difficult and research in these areas is
still in an early stage.