PSYCHOPHYSICAL FUNCTIONS OF THE SENSATION EVOKED BY ELECTRICAL-STIMULATION OF THE POSTERIOR URETHRA

Following electrical stimulation of the posterior urethra, visceral afferent nerves are excited that transmit sensory information perceived as an imminent desire to void. In the present study, some basic psychophysical relations involved in the sensations evoked this way were investigated. The results included the following. First, in the temporal integration relation, the relation between the sensory threshold (sT) and the duration of the stimulus (D) followed a power function: sT*DK = m, in which K and m are constants. Second, in 20 healthy subjects, the sensory threshold determined with increasing strength (sTi) and determined with decreasing strength (sTd) were linearly correlated (P≤0.001). The slope of the relations between sTi and sTd decreased with the duration of stimulus. Third, the sTi and sTd were inversely related to the frequency of the stimulus. Fourth, the relation between the mean reaction time (RT) and the stimulus strength (I) followed a significant power function fit after stimulation in the posterior urethra (R = 0.93, P≤0.001): RT = ∂ * I−n, in which ∂ and n are constants. Finally, stimulation of the penile skin either electrically, with vibration or with a cold stimulus, caused a significant increase in the sensory thresholds determined in the posterior urethra. The conclusion of the study was that sensations evoked by electrical stimulation of visceral afferent pathways in the posterior urethra follow psychophysical power functions similar to those of exteroceptive sensory modalities. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company