Target Cell Selection and Specific Synapse Formation By Identified Ly'Mnaea Neurons in Vitro

Abstract

Our research is aimed at determining both cellular and molecular mechanisms that underlie target cell selection and specific synapse formation in the nervous system. We have developed an in vitro experimental system which utilizes identified pre and postsynaptic neurons from the mollusc Lymnaea stagnalis. A giant presynaptic neuron, the right pedal dorsal 1 (RPeD1), re-establishes its specific synapses in culture with only postsynaptic target cells (such as visceral J, I), but not with non target cells (VF, RPB). In an attempt to begin to elucidate mechanisms that determine the specificity of synaptogenesis between Lymnaea neurons in vitro, we studied the behaviour of both target and non-target cell growth cones as they encountered RPeD1's growth cones for the first time. Utilizing time-lapse video imaging techniques, we demonstrate that RPeD1 growth cones attract and repel target and non-target cell growth cones respectively. We suggest that the specificity of synaptogenesis between RPeD 1 and both target and non-target cells is determined at the growth cone level and may involve release of a diffusible substance from the growth concs of RPeD 1.