The effect of injury on the properties of afferent fibres in the lingual nerve.

The receptor properties of mechanosensitive afferent fibres in the lingual nerve have been studied using electrophysiological techniques in cats. In normal animals some fibres responded only to mechanical stimulation of filiform or fungiform papillae but others also responded when a cold stimulus was applied to the receptive field. Twelve weeks after crushing the lingual nerve, the regenerated fibres had slower conduction velocities but the receptor properties were not significantly different from normal. Twelve weeks after sectioning the lingual nerve, there was a greater reduction in conduction velocities and in addition the mechanoreceptive fields were smaller, force thresholds were higher, adaptation times longer and a smaller proportion of fibres responded to a cold stimulus. These results suggest that section injuries are more likely to result in persistent sensory abnormalities than crush injuries.