Match and Mismatch of Taste, Odor, and Color is Reflected by Electrical Activity in the Human Brain

Abstract

We aimed at elucidating the relationship between odor, taste, color, and food stimuli where subjects were studied either with questionnaires or in electrophysiological experiments. First, a total of 144 word pairs were rated by 660 subjects who determined whether the first stimulus (odor or taste word) matched the second one (color or food word). In an electrophysiological experiment, EEG was recorded from 30 electrodes in 24 healthy adults while clearly matching, or nonmatching, word pairs were presented on a monitor. Evoked potentials were computed for different stimulus classes (matching or nonmatching combinations of odor or taste and color or food words). Six components were identified and compared between conditions. For most components, field strength (GFP) was lower for nonmatching than for matching word pairs. In addition to late effects, electrical brain activity was influenced by experimental conditions as early as at 100 ms latency. Most effects observed were in the time range between 100 and 250 ms. Our data show how color and food words are differently affected when paired with odor or taste words. Complex interactions between stimulus modality (taste/odor) and different target words (color/food) occurred depending on whether the pairs were seen by the subjects as appropriate or inappropriate. Topographical effects indicated that different neural populations were activated in different conditions. Most interestingly, there were many cognitive effects occurring quite early (on the order of 100 ms) after stimulus presentation, and our results suggest rapid cognitive processing of information on odor, taste, color, and food items. This is an important prerequisite for the preconscious and fast choice of food items in everyday behavior, and the data confirm earlier findings on rapid and preconscious semantic processing in the visual cortex.