Olfactory imprinting enhances associative learning and memory in C. elegans

Learning and memory are fundamental processes for an organism's normal physiological function. Learning can occur at any stage of the organism's physiological development. Imprinted memories formed during the early developmental stage, unlike learning and memory, can last a lifetime. It is not clear whether these two types of memories are interlinked. In this study, we investigated whether imprinted memory influences adult learning and memory in a C. elegans model system. We trained the worms for short-term (STAM) and long-term associated memory (LTAM) towards butanone (BT) after conditioning them for imprinted memory towards isoamyl alcohol (IAA). We observed that these worms had improved learning abilities. However, functional imaging revealed that the worms had a long-term depression in the firing pattern in the AIY interneuron, indicating that there were significant changes in neuronal excitation pattern after imprinting, which could explain the enhanced behavioural alterations in animals after imprinting.