Tap withdrawal circuit interneurons require CREB for long-term habituation in Caenorhabditis elegans

We investigated the role of the Caenorhabditis elegans CREB (cAMP response element binding protein) homologue, crh-1, in response to tap (nonlocalized mechanosensory stimulation) and tap habituation. Worms with a loss-of-function mutation in crh-1 performed smaller reversals in response to tap than did wild-type worms and did not show long-term memory for spaced training 24-hr posttraining; however, they did show short-term habituation to tap stimuli when stimuli were presented at both 10-s and 60-s interstimulus intervals, and showed 12-hr intermediate memory for spaced habituation training (intermediate-term memory). Expressing CRH-1 broadly throughout the nervous system and in a subset of interneurons of the tap withdrawal circuit, but not in the mechanosensory neurons, rescued the long-term memory defects observed in crh-1 mutants. Here we show for the first time that CREB is required for long-term habituation and show that the interneurons of the tap withdrawal response circuit are the locus of plasticity for long-term mechanosensory habituation in C. elegans.