Operant conditioning in Lymnaea: Evidence for intermediate- and long-term memory

Aerial respiration of the pond snail, Lymnaea stagnalis, can be operantly c onditioned; however, the parameters necessary to produce long-term (LTM) or intermediate term memory (ITM) have not previously been investigated. We c onducted training using procedures that varied in the duration of the train ing session, the number of training sessions per day or the amount of time between subsequent training sessions (Sn. We found that by varying the dura tion and frequency of the training session learning could be differentially produced. Furthermore, the ability to form LTM was dependent not only on t he duration of the training session was also the interval between training sessions, the SI. Thus it was possible to produce ITM. which persists for u p to 3 hr, and not form LTM, which persists at least 18 hr. Learning, ITM, and LTM can be differentially produced by altering the SI, the duration of the training session, or the number of training sessions per day. These fin dings may allow us to begin to elucidate the underlying neural mechanisms o f learning, ITM, and LTM.