ABSTRACT
This chapter describes the functional characteristics of the primary sensory neurons innervating the cornea of the eye, a simple tissue that is exclusively supplied by nociceptive neurons. The experimental use of this model is providing answers to some of the unsolved questions regarding the functional roles of primary nociceptive neurons and their interactions with target cells. Based on extensive electrophysiological studies analyzing the responsiveness of corneal sensory axons to controlled mechanical, thermal and chemical stimulation of the cornea, corneal neurons were classified functionally as mechanosensory, polymodal and cold sensitive neurons. A separate functional type of corneal sensory neurons is the cold-sensitive neuron. Transduction of the various forms of energy by peripheral nerve endings of nociceptive neurons occurs presumably through separate membrane mechanisms. A more precise idea of the ionic mechanisms involved in the generation of nerve impulses by peripheral axon terminals of primary nociceptive neurons may be obtained from the electrical changes evoked in single nerve terminals by noxious stimuli.
