McMaster University

McMaster University

Faculty of
Health Sciences

Stress contributes to establishment of preferred places by mice exploring new environments

Published: January 26, 2010

Why do we like to return to places we’ve been before, whether it is home or a favourite coffee shop or even the same chair in that coffee shop? Could it be that when stress levels are high, we tend to establish and feel attracted to these preferred places?

Canadian and Israeli researchers have found that what appears to be random travelling of mice is actually a pattern. During exploration of a new environment, mice establish preferred places, visited sporadically and marked by the performance of twists and turns.

The study by researchers at McMaster University in Canada and Tel Aviv University in Israel provides evidence that the formation of these places is increased by stress, and suggests that the tortuous movements improve the interpretation of the visual scene, enhance the memory of the place and provide the mouse with multiple views that turn the established places into navigational landmarks.

Details are published in the latest issue of the open-access journal PLoS Computational Biology.

"Our findings have implications for research related to exploration of novel environment, navigation and locational memory," said Anna Dvorkin, lead author of the study and a postdoctoral fellow in McMaster’s Department of Biochemistry and Biomedical Sciences.

"The establishment of preferred places is related to stress — the more stress experienced by the animal, the more likely it is to form these landmarks, which help in the navigation of a new environment."

Using advanced computational tools, the authors show how a particular type of place (called a knot) is formed and then used by mice. The knots, and other preferred places discovered earlier, contribute to the understanding of how the animals map the environment, and what they try to accomplish.

In an empty arena devoid of proximal cues, the rich perceptual inputs generated by the twisting and turning could improve the mouse's view of the environment and more generally enhance or even embody for the mouse the memory and significance of this place by tagging it with a place-specific perceptual signature, according the authors.

Exploration is a central component of human and animal behavior that has been studied in rodents for almost a century. It is presently one of the main models for studying the interface between behavior, genetics, drugs, and the brain. Until recently, rodents' exploration of an open space has been considered to be largely random. Lately, this behavior is being gradually deciphered, revealing reference places established and used by the animals for navigation.

Portrayal of how behavior is structured within and around knots in normal animals can later be used to study how this behavior is affected by pharmacological and genetic manipulations.

The study was supported by grants from the Natural Sciences and Engineering Research Council of Canada and the Israel Science Foundation.

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