THE AFFERENT FUNCTIONS OF NON-MYELINATED OR C FIBERS

Abstract

Non-myelinated fibers from the dorsal roots, stimulated in peripheral nerves after block of myelinated fibers by strong shocks, produce typical reflex effects. In animals under dial anaesthesia there is a differential depression of the reflex effects of stimulation of B fibers as compared to C (confirming Clark, Hughes and Gasser), and under ether a differential effect in the opposite direction, to such an extent that no C responses may be obtained at a degree of anaesthesia when B responses are vigorous. The authors'' previous conclusions that such fibers were not sensory followed from expts. under ether only. Under local anaesthesia only, minimal stimulation of B and C fiber groups separately indicates that B fibers are in general more effective than C in producing reflex effects, which corresponds to previous findings that the larger the myelinated fiber, the greater the reflex effect of its stimulation. Since "motor" or "antidromic" effects are produced by peripheral stimulation of non-myelinated dorsal root fibers, and only of these, the question is raised whether they normally in the animal body may be capable of transmitting messages in both directions.