The Influence of Taste Stimuli and Illumination on Electrogastrogram Measurements

Abstract

An electrogastrogram (EGG) is considered to be an index to the autonomic nervous system of the digestive organs. In the present study, we attempted to clarify whether or not an EGG can be used to evaluate the influence of illumination, and what kinds of effect taste stimuli and illumination have on the autonomic nervous system. In this study, we used the ratio of the normal wave component of the EGG (EGG-NR: 2-4.5 cpm power/1-10 cpm power) and the amplitude of a normal wave (EGG-NI: integrated EGG of 2-4.5 cpm). Thirteen healthy males participated in 16 experimental conditions (4 lighting conditionsϫ4 taste stimuli). The four lighting conditions were set by combinations of illuminance levels of 200 and 1500 lx and color temperatures of 3000 and 7500 K. The four taste stimuli were sweet (glucose), salty (salt), sour (acetic acid), and bitter (quinine). The changes in EGG-NR and EGG-NI were compared for different taste conditions. The results showed that EGG-NI was not significantly affected by the different taste conditions. However, the main effect of taste on EGG-NR was significant: sweet and salty tastes were significantly higher than the bitter taste. EGG-NR and EGG-NI in different lighting conditions were also compared. The main effect of different color temperatures was also significant, but the illuminance level did not affect EGG-NR. EGG-NR increased significantly at the lower color temperature. On the other hand, EGG-NI significantly increased at the lower illuminance. These results suggest that parasympathetic nervous activity has a predominant effect on gastric activity in different lighting environments. Therefore, EGG measurements may be useful indicators for illumination environment studies.

The Effect of Season and Light Intensity on the Core Interthreshold Zone

“…Intensity of lighting was set at 500 and 1,000 lx in the present study, substantially lower than 2,000 lx to 5,000 lx set at by Foret et al (1993). However, Jin et al (2007) demonstrated the effect of lighting on EEG when their subjects were exposed to 200 lx and 1,500 lx for 20 min on each trial. So the lighting conditions set in the Kakitsuba et al, 2007Kakitsuba et al, , 2009 present study seem to be appropriate for evaluating change in autonomic control of core temperature.…”

“…Dijk et al (1991) also reported that arousal level increased and hypothermia was alleviated in high illuminance conditions. On the other hand, some studies (Kim and Tokura, 2000;Tokura, 2005;Jin et al, 2007) reported that parasympathetic nervous activity increased with inhibition of sympathetic nervous activity in high illuminance conditions. Thus, the effect of exposure to light on autonomic functions has not been clearly evaluated.…”

“…The secretion of melatonin is strongly associated with the circadian rhythm of core temperature. Concerning the nonvisual pathway, the literature has demonstrated the effect of light exposure on the autonomic nervous system (e.g., Jacobs and Hustmyer, 1974;Kobayashi and Sato, 1992;Jin et al, 2007), as well as the thermal regulation system (e.g., Scheer et al, 2005), showing the interaction of environmental light and the SCN in body temperature regulation. Since the pineal body is located near the hypothalamus, which regulates core temperature, reciprocal or one-sided afferent information may be incorporated into the body temperature regulation system, and the results suggest that afferent information via the nonvisual pathway on light exposure may play a significant role of reducing the autonomic control of core temperature.…”

Effects of Monochromatic Light on Time Sense for Short Intervals

“…The color temperature of the rising and setting sun is about 2000 K, while that of sunlight at midday reaches around 7500 K. Human beings have developed under this natural light environment and have adapted to it, as have other organisms. It is generally accepted that sympathetic and central nervous activities are more stimulated under the higher color temperatures (Noguchi and Sakaguchi, 1999;Yasukouchi and Ishibashi, 2005;Jin et al, 2005;. Likewise, it is accepted that short wavelength light inhibits melatonin secretion at night (Morita and Tokura, 1998;Brainard et al, 2001;Lockley et al, 2003Lockley et al, , 2006Cajochen et al, 2005;Hanifin et al, 2006).…”

Physiological Measurements for Evaluation of Human-Environment System

“…Recently, we evaluated the relationship between taste sense and illumination by using the taste threshold, amount of saliva (Katsuura et al, 2005) and EGG (Jin et al, 2005).…”