Abstract
We have previously reported that wearing of mouth guard (MG) improves dynamic visual acuity (DVA) during head rotation. Some subjects, however, showed the opposite effect of the MG wearing on DVA. To test a hypothesis that unpleasant feeling caused by MG affects DVA, we monitored pupillary responses induced by flash stimulation and evaluated the autonomic nervous activity. The difference between the initial pupil diameter and that at 2.4 seconds after flash stimulation was used as sympathetic nervous activity, and the maximum velocity of pupil constriction was used as parasympathetic nervous activity (Yamaji et al., Syst Comput Jpn. 31:22-31, 2000). Seven healthy subjects (21-46 years) wore a comfortable (compact and thin) MG or an uncomfortable (large and thick) MG for 20 minutes and pupillary flash responses were monitored before, during and after MG wearing. We found that the autonomic nervous activities were clearly modulated by the uncomfortable MG. We will discuss the relationship between MG wearing and the autonomic nervous activity. [J Physiol Sci. 2007;57 Suppl:S241]
