A possible age-related decrement in the conduction velocity of Aplysia neuron R2.

In late winter and in spring, the conduction velocity of the R2 axon of Aplysia californica is 0.48 m/sec or more in all specimens. However, in the summer, fall and early winter, some sexually mature animals exhibit markedly diminished R2 conduction rates (as low as 0.24 m/sec). It is possible that this reduced velocity is a reflection of the age of the specimen from which the axon is taken.