LONG-TERM HABITUATION IS PRODUCED BY DISTRIBUTED TRAINING AT LONG ISIS AND NOT BY MASSED TRAINING OR SHORT ISIS IN CAENORHABDITIS-ELEGANS

To begin an investigation of the cellular processes that underlie long -term memory in the nematode Caenorhabditis elegans, it is first neces sary to determine that C. elegans is capable of retention over 24 h, a nd to investigate the factors that may influence the expression of lon g-term memory. In the present study, the effects of stimuli number, in terstimulus interval (ISI), and training procedure on longterm retenti on of habituation were tested in C. elegans. At a long (60-sec) ISI, d istributed training sessions produced long-term habituation retained f or 24 h, whereas massed training sessions or training with few stimuli did not. When training was performed at a short (10-sec) ISI, long-te rm habituation was not detectable with testing at either a 10- or a 60 -sec ISI. The long-term habituation observed after distributed trainin g sessions at a 60-sec ISI was consistently expressed when the trainin g procedures were varied. Thus it is clear that C. elegans can reliabl y express long-term retention for distributed training sessions at a 6 0-sec ISI, making the system a candidate for further investigations in to the cellular processes supporting memory.