EFFECTS OF CHANGING INTERSTIMULUS-INTERVAL DURING HABITUATION IN CAENORHABDITIS-ELEGANS

The role of the interstimulus interval (ISI) in habituation in Caenorh abditis elegans was explored by examining the effect of changing the I SI on habituation and on spontaneous recovery from habituation. When h abituation stimuli were delivered at variable ISIs with an average of 10 s, recovery was slower than when habituation stimuli were delivered at fixed 10-s intervals. There were no differences in recovery follow ing either fixed or variable stimulation at a 60-s ISI. The effect of shifting to a different ISI during habituation training was also explo red. A 60-s ISI affected habituation at a 10-s ISI, but a 10-s ISI did not influence habituation at a 60-s ISI. Therefore, habituation must be viewed as an ongoing equilibrium of a number of cellular processes- some decrementing, some facilitating-that are differentially activated at different ISIs.