INTERNEURONES MEDIATING THE ESCAPE REACTION OF THE MARINE MOLLUSC CLIONE LIMACINA

Neural mechanisms underlying the escape reaction have been extensively studied for over 20 years in many species of animals belonging to several different phyla (for a review, see Eaton, 1984). Among molluscs, the escape reaction has been most thoroughly studied in Tritonia. In this animal a strong mechanical or chemical stimulus applied to the posterior part of the body evokes swimming (for a review, see Getting, 1983; Getting and Dekin, 1985). Electrophysiological experiments on the isolated nervous system revealed that neurones constituting the central pattern generator (CPG) for swimming were strongly depolarized in response to sensory stimulation and that this depolarization caused rhythmic activity in the CPG. However, attempts to identify command neurones mediating the escape reaction in Tritonia have failed (Getting, 1983).