The effect of nerve stump length upon mammalian taste responses.

A decline in the magnitude of the summated responses evoked by taste solutions began about 1 h following IXth nerve transection. In 41 IXth nerves transected at different lengths we found a linear relationship between the length of the IXth nerve stump remaining attached to the tongue and the time for the taste response amplitude to fall to 50% of its control magnitude. The existence of a nerve stump length dependency suggests that IXth nerve taste responses in the gerbil are maintained by the axonal transport of trophic substances to the tongue.