NEURONAL BASIS OF RHYTHMIC PUMPING IN BALANUS-HAMERI

Rhythmic activity, having a period similar to that of the pumping behavior of the intact barnacle, can be recorded from the isolated ventral ganglion of B. hameri. Evidence is presented for a rhythm generated presynaptically by PSP [post-synaptic potentials] which have an excitatory effect on 1 set of neurons and an inhibitory effect on an out of phase set of neurons. Electric shock results suggest that the rhythm arises through a relaxation oscillator mechanism, and lesion experiments suggest that the rhythm arises in the central region of the ganglion. Deafferentation indicates that the rhythm''s generation is entirely endogenous, although it can be affected by sensory input from the cirri.