What the Worm Remembers

Environment plays an important role in memory retrieval, say U of T researchers. In fact, we may remember information more easily in the setting where we first learned it.

In a study of olfactory learning, PhD candidate Eric Law and his supervisor, Prof. Derek van der Kooy, used C. elegans (worms with completely sequenced genomes) to demonstrate that animals absorb information about their environment and modulate their behaviour accordingly.

The researchers placed worms in a salt medium, exposed them to the smell of benzaldehyde and trained them to associate the smell with starvation. When the worms were returned to this environment, they showed a dislike for the odour. But when placed in a different salt medium, they did not display an aversion. “During training, the worms learn about whether smell predicts starvation, and it becomes apparent that environmental cues can exert control over whether the animals will respond to the odour as a cue for starvation,” says Law, who studies medical genetics and microbiology. “This is an important bridge between psychology and neurobiology – environmental signals are stored in the nervous system separately from a particular memory, so that they can facilitate or inhibit your ability to recall the memory.”

The next step is to find the gene involved in processing environmental cues, says Law.