Context conditioning in habituation in the nematode Caenorhabditis elegans.

Habituation has traditionally been considered a nonassociative form of learning. However, recent research suggests that retention of this nonassociative form of learning may be aided by associations formed during training. An example of this is context conditioning, in which animals that are trained and tested in the presence of a contextual cue show greater retention than animals trained and tested in different environments. This article reports context conditioning in habituation in the nematode Caenorhabditis elegans. The results showed that retention of habituation to tap at both 10- and 60-s interstimulus intervals was significantly greater if training and testing occurred in the presence of the same chemosensory cue (NaCH3COO). This context conditioning showed both extinction and latent inhibition, demonstrating that these simple worms with only 302 neurons are capable of associative context conditioning.