Meeting Abstract

45.5  Tuesday, Jan. 5  The shadow response of RPeD11, in Lymnaea SUNADA, Hiroshi; SAKAKIBARA, Manabu*; Tokai University manabu@tokai.ac.jp

Stress, especially that elicited by ecologically relevant stressors (e.g. Predator detection) enhances long-term memory (LTM) formation in the pond snail, Lymnaea stagnalis. In addition, predator detection elicits a suite of so-called vigilance behaviors one of which is a heightened response to a shadow (i.e. Often the complete withdrawal of the snail into its shell). The shadow withdrawal response is mediated by so-called dermal photoreceptors located primarily on the foot, mantle cavity, and skin around the pneumostome area. Here we asked whether we could obtain a neural correlate of the heightened withdrawal response elicited by a shadow following predator detection. We measured the electrophysiological properties of ‘Right Pedal Dorsal 11 (RPeD11)’, an interneuron that plays a major role in withdrawal behavior of the animal. In naive semi-intact preparations (i.e. snails not exposed to predator scent) the shadow stimulus elicits a small depolarization in RPeD11 which is mediated by dermal photoreceptors making a mono-synaptic connection to RPeD11. In stressed snails (i.e. exposed to predator scent) there are a number of significant changes in the intrinsic membrane properties of RPeD11 compared to naive preparations. RPeD11 is significantly more depolarized (~8mV) and the input resistance is significantly greater. Moreover in these ‘stressed’ preparations the response to the shadow stimulus is of a significantly longer duration leading to an increased RPeD11 response.