Aug. 2, 2004 The environment plays an important role in memory retrieval, says a new University of Toronto study.
In a study of olfactory learning published in the July 27 issue of Current Biology, U of T's Eric Law, a PhD candidate, and his supervisor, Professor Derek van der Kooy of the Department of Medical Genetics and Microbiology, used C. elegans, a worm whose genome has been completely sequenced, to demonstrate that animals absorb information about their environment and modulate their behaviour accordingly.
The researchers first placed worms on agar plates treated with a salt medium, exposed them to the smell of benzaldehyde and trained them to associate the smell with starvation. If a worm was returned to the salt medium where it had been trained, it showed a distaste for the benzaldehyde odour, but it did not demonstrate this memory in a different salt medium.
Law likened the results to remembering something more easily if you were in the same environment where you had first learned it.
"During training, the worms learn about whether smell predicts starvation, and it becomes apparent that environmental cues can also trigger the memory of odour as a cue for starvation," said Law.
"This is something people intuitively said was important. This is an important bridge between psychology and neurobiology. Affecting an environment affects your ability to learn."
The researchers have also identified a mutation that affects the environment's role in memory recall. When you test and train the worms with this mutation in a different environment, they get confused and don't associate the environment with what they've learned.
The next step is to find the specific gene involved in processing environmental cues, says Law. Once it is identified, researchers will be able to search for similar genes in humans in order to shed light on the workings of human memory.
This study was supported by the National Sciences and Engineering Research Council of Canada. U of T post-doctoral fellow William Nuttley also contributed to the research.
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