[Olfactory stimulation and contingent negative variation (CNV) (author's transl)].

In addition to olfactory evoked responses (Fig. 1a) the vertex-negative voltage shift was registered in 20 normal adults. Fig. 2 shows this potential for an olfactory indicative stimulus followed by a tone burst or flash sequence, which are stopped by the test person's manual reaction. In Fig. 3 two alternating odorous stimuli are presented, one of which is followed by the tone. The selective expectancy wave is followed by the tone. The selective expectancy wave is only built up by the marked olfactory stimulus. For the first time CNV can be used as a clinical investigation tool to confirm central perception of odorous stimuli and furthermore to objectivate impaired central odour discrimination (parosmia).