9.27.2005They are free nerve endings.
C-fibers are unmyeliniated and as a result, have a slower conduction velocity; lower than 2 m/s. These fibers are associated with chronic or dull pain. C-fibers are associated with sensations of cold, as well as mechanical and chemical stimuli. The density for cold receptors in the skin is greater than the density of warm-receptors (by a factor of 5). It is thought that most or all C fibers are nocireceptors (responding only to noxious stimuli).
Aδ fibres are thin, myelinated fibers with a large conduction velocity (2 to 30 m/s) and are associated with acute pain. In a real life situation, this is the sharp pain that triggers reflexes which result in the "pulling away" from the stimuli (ie: yanking hand away from hot stove). A certain proportion of Aδ fibers are also associated with sensations of heat and pressure.
1) Should philosophers switch to Aδ fibers firing as physical correlates for pain?
2) Do you think Kripke was a masochist based on his use of C rather than Aδ fibers?