Analysis of autonomic nervous reactions accompanying nausea induced by visual stimulation *
In this study, the autonomic nervous reactions accompanying nausea induced by visual stimulation were analyzed quantitatively in humans. Nineteen healthy subjects who were sitting, and who were both physically rested and relaxed, were exposed to a six-minute oscillating movie as visual stimulation. Before, during and after watching the movie, gastric myoelectric activities (EGG), heart rate (ECG), respiration frequency, perspiration volume from the surface of the right palm and forehead, and peripheral blood flow in a forefinger were measured in each subject. These items were analyzed as an index of autonomic nervous activities. The examination period was divided into four phases, i.e., phase 1 : control, phase 2 : the first half of watching the movie, phase 3 : the latter half of watching the movie and phase 4 : the five minute period after watching the movie. The scores for 13 items of subjective symptoms, which the subjects were questioned about before and after watching the movie, showed that the visual stimulation sufficiently evoked nausea. Analysis of the EGGs showed that the amplitude of gastric myoelectric activities were augmented in phase 3 as compared to those in phase 1 (P<0. 05). However, distribution of amplitude of bradygastria, normalgastria and tachygastria did not change significantly among the phases. The heart rate decreased in phase 2 (P< 0. 05), but this decrease was temporary and soon returned to the control level. The respiration frequency increased during the phases 2 and 3 (P< 0. 05). The perspiration volume from the palm showed no change during the examination but that from the forehead increased during watching of the movie (P< 0. 05). Peripheral blood flow temporarily decreased in phase 2 (P<0. 05), but returned to the control level in the following phases. In 6 fasting subjects, augmentation of EGG amplitude in phase 2 was smaller than that in the other 13 postprandial subjects. The subjective nausea symptoms score in the fasting subjects was lower than that in the postprandial subjects (P< 0. 05). The expressions of these autonomic nervous reactions were presumed to be the preparations for vomiting, and the results of unconscious activities to prevent the transition to vomiting from nausea. In conclusion, nausea is attended by fast and temporary parasympathetic nervous activity and the mixture of sympathetic and parasympathetic nervous activities in the latter phases. (Accepted on September 10, 2002) Kawasaki Igakkaishi 28(4) : 229 -241, 2002
