[Modulation of evoked potentials following electrical tooth stimulation by pre-auditory stimulus]

Modulation of evoked potentials following electrical tooth stimulation (Dental EPs) and visual analogue scale (VAS) were studied in 11 healthy adult volunteers to investigate the possibility of controlling reaction of pain sensation by using pre-auditory stimulus. They were recorded by these two paradigms. 1) Only electrical tooth stimulation delivered in random interval. 2) A preceding tone beep, to enable subjects to anticipate the coming tooth stimulus. Preceding time, inter stimulation intervals (ISI) were 0.5, 1.0, 3.0, 5.0, and 7.0sec. The results were as follows: 1) The Dental EPs were recorded in every volunteer, and the N2-P2 amplitude was the largest at vertex areas (Cz). 2) The P2 latency and N2-P2 amplitude were modulated by the preceding tone beep, reduced in ISI = 0.5 and 1.0sec, and increased in ISI = 5.0 and 7.0sec., and a linear correlation was found between their variations. 3) There were no significant differences in the VAS score between each paradigm. These findings suggested that: 1) The late component of Dental EPs reflects not only the physiological process of the pain sensation but also psychological process of expectation and anxiety. 2) Pre-auditory stimulus and time lag between pre-auditory stimulus and electrical tooth stimulation influence the psychological process and modulate the Dental EP result.