Role of mechanoreceptive afferents in two-point discrimination: A simulation based modeling study

摘要

Two-point discrimination test is used to measure the capacity of human for detecting two stimuli which are simultaneously applied on different skin sites close to each other. The results of this test depends on the innervation density of cutaneous mechanoreceptive afferents. In literature, it is suggested that two-point discrimination capacity depends on the functioning of slowly adapting mechanoreceptors. In this study, responses of mechanoreceptive afferents on the distal phalange of a monkey were simulated with one or two point stimulation on TouchSim simulation tool. Simulated responses were used to train a neural network to discriminate one and two point stimulation conditions. In order to assess the roles of different types of mechanoreceptive afferents, subpopulations including one or two types of afferents were isolated from the population and tested with the neural network. In contrary to literature, results suggest that the information delivered by rapidly-adapting type I (RA) afferents is superior to information delivered by slowly-adapting type I (SA1) and rapidly-adapting type II (PC) afferents in a two-point discrimination task. On the other hand, in order to successfully detect two-point stimulation, information from both RA and SA1 is necessary. Psychophysical experiments are suggested to test this results in human subjects.