High voltage with little current as an unconditional stimulus for taste avoidance conditioning in Lymnaea stagnalis

Abstract

A new and better taste avoidance conditioning paradigm for Lymnaea has been developed that replaces the previously used tactile unconditional stimulus (US) with an brief electrical stimulus (1000V, 80μA), while continuing to use a sucrose application to the lips as the conditional stimulus (CS). With 15 paired CS-US presentations on a single day, we were able to elicit both short-term memory (STM) and long-term memory (LTM). The LTM persisted for at least one week. While STM was elicited with 5, 8, or 10 paired presentations of the CS-US on a single day, LTM was not. The new US used here was more consistent than the previously used US, and this stimulus consistency may explain why 15 paired CS-US presentations now result in LTM formation.

Keywords: ANOVA; CGC; CS; High-voltage stimulus; IPSP; ITM; LTM; Long-term memory; Lymnaea stagnalis; N1M; N3t; STM; Short-term memory; TAC; Taste avoidance conditioning; US; analysis of variance; cerebral giant cell; conditional stimulus; inhibitory post-synaptic potential; intermediate-term memory; long-term memory; neuron 1 medial cell; neuron 3 transient cell; short-term memory; taste avoidance conditioning; unconditional stimulus.