Synaptic interaction between the giant interneuron and the giant motorneuron in the hermit crab, Pagurus pollicarus

Abstract

1. 1. An anatomical and physiological investigation was made of several components in the withdrawal escape response of the hermit crab, Pagurus pollicarus. 2. 2. In the fused last thoracic-first abdominal ganglion, the giant axon (GA) synapses with the giant motor (GM) neuron which innervates the abdominal flexor muscles. 3. 3. The synapse is unidirectional, conducting impulses only from the GA to the GM. 4. 4. The synaptic delay time is less than 0.4 msec. 5. 5. Concentrations of MgCl 2 and MnCl 2 which normally block chemical synapses were ineffective in interfering with GA-GM transmission. 6. 6. The GA-GM synapse was reversibly blocked by 0.5 mM DNP. 7. 7. It is concluded that GA-GM connection is a rectifying electrical synapse.