A discovery made by a research team from McGill University sheds new light on the mechanisms of memory retention, which operate despite constant variations in brain activity.
"It's a question we've been asking for a long time: if the brain's memory structures are constantly changing, how can our memories remain so stable? Our results provide an explanation," says Adrien Peyrache, associate professor and research director.
For several months, the team tracked these neurons in mice using miniature microscopes fixed to the animals' heads. They discovered that the structure of the directional system remained intact, even when the hippocampus was reorganizing.
They also discovered that when exploring a new place, what is called the "brain's compass" would quickly establish a directional reference point—essentially, it would determine an orientation—and retain this sense of direction when returning to the same place several weeks later.
"These results highlight a surprising contrast," says Adrien Peyrache. "The hippocampus can reorganize its activity over time, but the directional system provides a very stable foundation for interpreting spatial information."
These observations are relevant for Alzheimer's disease research, he adds, because getting lost or feeling disoriented is often one of the first warning signs of the disease; in fact, it sometimes manifests before any clear memory loss is noticeable.
"If we understand the mechanisms that maintain spatial stability, we may be better able to identify the cause of their deterioration and improve early detection and therapeutic strategies," concludes Adrien Peyrache.