Ottawa University scientists have found that narrowing the effect of astrocyte (a type of brain cell) can help prevent cannbis memory effects.
They said it might be possible to block it in medicines based on cannabis, the BBC reported.
Cannabis floods the brain with a host of chemicals which mimic one of its own subtle signalling systems, leading to pronounced changes in mood and memory.
Scientists are trying to harness the power of these chemicals, called cannabinoids, in pharmaceuticals aimed at conditions such as multiple sclerosis and chronic pain.
The doses of cannabinoid are carefully controlled to avoid the "high" feeling.
The work by the Ottawa University researchers may shed light on how one of the best known cannabinoids, THC, acts on the brain.
Their work suggests that, when it comes to affecting memory, THC is acting not, as might be expected, on the brain's neurons, but on a brain cell called an astrocyte.
They bred mice whose astrocytes could not be affected by THC, and found that their spatial memory was unaffected by the dose.
This discovery could help drug companies reduce the risk of unwanted side effects when using THC in their products, they suggested.
However, possibly more importantly, it could shed light on the brain's own chemical pathways, the "endocannabinoid" system.
"Just about any physiological function you can think of in the body, it's likely at some point endocannabinoids are involved," said Dr Xia Zhang, one of the researchers.
Understanding how this system works could lead to ways to make it work better, he suggested.
"We may find a way to deal with working memory problems in Alzheimer's," he said.
The scientists report their finding in the journal Cell.