Intracellular studies on the nervous system of an echinoderm

Intracellular techniques have been used to study the chemical synapse across the basement membrane that separates the ectoneural nervous system from the hyponeural. Lucifer Yellow dye fills have shown that all the neurones break up into a fine plexus of neurites where they make synaptic contact. The hyponeural motor cells show inhibitory and excitatory junction potentials concomitant with activity in the ectoneural system. These junction potentials summate to produce spike potentials in the axon hillock region of the motor axons. The motor nerves are inhibited on one side and excited on the other during rapid arm flexures.