ABSTRACT
It is clear that at least two neural systems underlie the detection of vibrotactile stimuli-the highly tuned P system, with its U-shaped frequency characteristic and its capacity for spatial and temporal summation, and the NP system, with its flat frequency characteristic and absence of spatial and temporal summation. But what are the specific physiological mechanisms underlying these systems? To answer this question, the first thing that must be considered is the properties of the tactile mechanoreceptors and their associated nerve fibers in the glabrous skin of the hand, where there are not just two but at least four known types of mechanoreceptors and associated nerve fibers that mediate the sense of touch.
