The CNS is responsible for processing the information it receives from the cutaneous nerves that detect a given stimulus, and then identifying the kind of sensory inputs which project to a specific region of the primary somatosensory cortex.
The first one, Meissner's corpuscles are encapsulated nerve endings attached to the epidermis in the dermal papilli that detect changes in texture and vibrations.
Merkel's discs are arborizations of nonmyelinated axons that end in terminals on specialized tactile cells and which detect sustained touch and pressure.
[2] The size of the receptive fields in turn explains why almost any given stimulus to the human skin can potentially activate a very large number of nerve terminals.
The sensory modality that is detected by the afferent fibers is an important factor to consider because it determines the pathway that the dorsal root ganglion neurons will take within the central nervous system.
The sensory neurons coming from the body synapse in the dorsal horn of the spinal cord, bringing in information about touch sensations (epicritic), or modalities of pain (protopathic).
[4] When both sensory pathways reach the integrating center that is the thalamus, they make their final ascent to the somatosensory areas in the postcentral gyrus of the cerebral cortex.