Processing of mechano- and chemosensory information in the lip nerve and cerebral ganglia of the snail Helix pomatia L.

Neurophysiologists have long been seeking simple model systems in which to analyze the neuronal mechanisms underlying the organization of behavior. The feeding behavior of molluscs has proved to be one of the most useful simple systems for the analysis of cyclical motor patterns, the interactions of central pattern generating interneurons, and the role of sensory inputs in the initiation and maintenance of the behavior. Considerable progress has been made in one or both of the first two aspects of this research in Lymnaea, Helisoma, Limax, Planorbarius, Pleurobranchaea, and Tritonia (for reviews see [3, 7, 8, 15]), and more recently, in Aplysia [39] and Planorbis [1]. The role of mechano- and chemosensory inputs in the organization of the feeding behavior was studied in at least twenty molluscan species (for a review see [3]). However, in only less than half of them was the analysis extended to the effect of tactile and chemical inputs on identified neurons in the buccal and cerebral ganglia which contain the feeding circuitry (Aplysia: [12, 22, 36, 41]; Pleurobranchaea: [9, 16, 17]; Tritonia: [2]; Helisona: [21]; Limax: [11, 14, 35]: Helix: [6, 19, 24-26, 32, 38]). In the present work I would like to review our earlier findings on the processing of mechano and chemosensory information in the lip nerves and cerebral ganglia of Helix pomatia L. These findings were published in a series of papers between 1982 and 1987 [19, 20, 24-26]. The results reviewed here prepared the way for the development of new lines of research in our laboratory on the plasticity and serotonergic modulation of feeding in this widely used experimental animal [27, 40].