Effects of Image Presentation Using a Head-Mounted Display on Muscle and Brain Activity during Swallowing

Abstract

Introduction: It is well known that humans have an increased sense of taste and consume more food when eating with others. This effect is called social facilitation of eating. We previously reported that self-images also have the effect of social facilitation of eating. In the present study, we investigated the effect of a head-mounted display (HMD) as a means of presenting self-images. Methods: Fourteen healthy adults (7 females and 7 males) were included in the study. The mean age of the participants was 20.4 years. The experimental conditions were as follows: the presentation conditions include the SG condition, in which an image was projected on the smart glasses, and the MT condition, in which an image was projected on the monitor. The stimulation conditions include the self-image condition (Self condition), in which the participant’s own image was projected, and the background image condition (Background condition), in which the background image was projected. Participants were asked to consume green tea jelly three times under the four conditions, which consisted of combinations of the presentation and stimulation conditions. Electromyography (EMG) and electroencephalography (EEG) were used to measure the muscle activity of the suprahyoid muscle group and brain activity, respectively. Results: The EMG of the “SG-Self” condition was significantly higher than that of “SG-Background” and “MT-Background” conditions. The EMG of the “MT-Self” condition was significantly higher than that of the “MT-Background” condition. In the EEG before the start of swallowing, “SG-Self” was significantly lower in the alpha band and higher in the beta band than “MT-Background”. The beta-alpha ratio was significantly higher for “SG-Self” than for “SG-Background” and “MT-Background” and higher for “MT-Self” than for “MT-Background”. Conclusion: These results suggest that self-images influence muscle and brain activities during swallowing, regardless of the presentation conditions, such as HMD or monitor.