Survival of functional synapses on crustacean neurons lacking cell bodies

Previous workers have demonstrated that some crustacean neurons remain capable of spike propagation and transmitter release and replenishment for months after removal of their perikarya. Here, it is shown that postsynaptic reactions to chemical synaptic input can also persist for months after removal of the soma of the postsynaptic neuron. Interneuron A of the crayfish abdominal cord receives chemically transmitting terminals of ipsilateral tactile afferents of the tail fan. The neuron's soma lies contralateral to its axon and dendrites at the caudal margin of the last abdominal ganglion. The region containing the soma was removed. Interneuron A unambiguously identified by receptive field, location, and size, survived and continued to respond sensitively to tactile input in better than 50% of the cases examined for more than 8 weeks. Cobalt filling of the active fiber in several 8-week-old preparations ruled out the possibility that the severed neurite had reconnected with a foreign soma.