Probing the Limits of Planarian Memory: Retention and Cocaine-Triggered Reinstatement of Operant Conditioned Behaviour

Planaria are a simple organism capable of basic forms of learning. While planaria can learn preferences and show familiarity with their environment, research into more complex forms of learning is sparse. Although some prior research shows planaria have the capacity to learn via reinforcement learning, the retention capability for complex behaviours like this remains uncertain. In this study, a Y-maze will be used to condition treatment subjects to select their least preferred side (a biased design). Cocaine will be used to reinforce treatment subjects, while water will be used for control subjects. Subjects will be assessed for learning at the end of training, and after a 14 day delay. Although planaria have been shown to undergo extinction and reinstatement, it is not yet known whether a reinstatement procedure can be used to restore memories forgotten due to the passing of time rather than after contingency breaking. This study will also investigate whether seemingly forgotten memories can be reinstated by exposing the subjects to cocaine prior to another round of testing.