Changes in the extracellular potentials produced by unmyelinated nerve fibre resulting from alterations in the propagation velocity or the duration of the action potential.
D000200:Action Potentials; D000818:Animals; D005110:Extracellular Space / Q000502:physiology*; D006801:Humans; D008959:Models, Neurological; D009412:Nerve Fibers / Q000502:physiology*; D011930:Reaction Time