Regeneration of central and peripheral synaptic connections in the locomotor system of the pteropod mollusc Clione limacina

• Published in: Invertebrate neuroscience 1997-06, Vol.3 (1), p.27-40
• Main Authors: Panchin, Y V, Zelenin, P V, Popova, L B
• Format: Article
• Language: English
• Subjects: Clione limacina; Marine
• ISSN: 1354-2516
• DOI: 10.1007/BF02481712

The neural network underlying rhythmic wing movements in the mollusc Clione limacina is well-studied. Two different groups of motoneurons innervate two distinct groups of wing muscles. The locomotor rhythm generated in the left and right pedal ganglia is synchronized by interneurons. When the axons of the locomotor motoneurons are crushed, numerous fine neurites sprout towards the denervated muscles and reach them in 8-15 days. At this stage motoneurons project to and synapse on not only correct but equally incorrect muscle targets. After 2 weeks of regeneration the number of incorrect neurites and synaptic connections begins to decrease and following 1.5-2 months all incorrect connections are eliminated, incorrect axons are withdrawn and the behavioral deficit is compensated. In this study the regeneration of interneurons and the growth profiles of inter- and motoneurons were also studied in vitro. Two individually isolated pedal ganglia were co-cultured in three different configurations: a) the wing nerve stump from one ganglion was fixed against the commissural stump from another ganglion; b) the wing nerve stumps were fixed against each other; c) the commissural stumps were fixed against each other. Under the above experimental conditions we found that the interneurons were able to cross only the contact between two commissural stumps, and in this case found their original targets, restored correct connections and synchronized the rhythm in two pedal ganglia. In contrast, motoneurons were able to cross all types of contacts.