統合脳科学Ⅲ

In order to clarify the effects of air-diluted Allyl Isothiocyanate (AITC) on human sleep, the odorless compound (control stimulus) and synthesized AITC was sprayed in the examination room while subjects slept at night. Sleep state and physical response to each stimulus was monitored with polysomnography. Behavioral response was evaluated on the latency between the time for the stimulus to arrive at the bedside and the time for each subject to press the button.

A total of 32 adults completed the study (17 hearing subjects and 15 deaf subjects). All but one subject with a blocked nose awoke within 152 sec and pressed the button within 245 sec. In sleep stage 2, the deaf subjects responded more quickly than the hearing subjects with corresponding latencies were 21.1 sec (range, 10-35) and 45.3 sec (range, 20-78), respectively. The density of AITC on awakening was less than 20 ppm.

The ion channel of TRP A1 in the somatosensory (in this case, trigeminal) nerve was revealed to respond to AITC. We presume that the congenital deaf is more sensitive to somatic sensation during sleep as a result of functional reorganization of the brain. Wasabi odor could be useful as a fire alarm to deaf people who failed to wake up with a conventional device.