New clues about animal navigation and how they know where they are at all times

In a new study, researchers have unlocked vital insights into the mysterious world of animal navigation, specifically focusing on how mice choose different strategies to navigate through their surroundings. 

The research, recently published in eLife, greatly improves our understanding of the complex neural processes that animals employ to orient themselves.

Focus of the study

The ability of animals to navigate their environment is a phenomenon that has remained largely enigmatic to the scientific community. 

While animal navigation is known to involve a range of strategies, exactly how animals decide which method to utilize has been unclear. 

This conundrum has led scientists to probe the nature and familiarity of an animal’s environment to decipher the underlying mechanism.

Barnes maze 

Traditionally, one popular method for exploring these navigational strategies in rodents has been the Barnes maze, where the creatures roam a circular arena until they locate an escape box hidden under several holes. 

However, the conventional Barnes maze’s efficacy has been questioned, mainly because it assumes that the mice maintain the same strategy throughout a trial.

“Typical Barnes mazes work under the assumption that the same strategy is maintained across a whole trial, so it is unclear whether they accurately capture the full range of navigational strategies used by mice,” said co-lead author Ju-Young Lee, a Ph.D. student at the Brain Science Institute, Korea Institute of Science and Technology (KIST).

How the research was conducted 

The team developed an automated variant of the Barnes Maze, enabling them to randomize the start and goal positions without compromising the integrity of the experiment. 

“Our maze is similar to the Barnes maze in that mice explore an open arena and navigate to a goal chosen among 24 doors evenly spaced along the edge of the arena. The difference with ours is that it features two luminous objects inside the arena as orienting cues, and the mice start at the edge, instead of the center,” explained co-lead author Dahee Jung.

During a meticulous 15-day examination period, the researchers closely monitored 20 mice (10 males and 10 females) undertaking the maze. What followed was an intensive acquisition phase and a reversal phase, including a probe test. 

What the researchers learned 

Interestingly, despite variations in the maze setup, they discovered that the learning rates and spatial strategies were comparable to those reported in the conventional Barnes maze. This crucial finding further validated their approach.

The researchers analyzed how the mice utilized visual cues and how their navigational patterns evolved during the trial. They noticed that the mice displayed a preference for vestibules near the goal location, supporting the theory that luminous markers guided their spatial awareness.

The team’s intricate examination led them to conclude that mice used a blend of three navigational strategies: random, spatial, and serial search. This multifaceted approach demanded the development of models combining all three strategies, which proved pivotal in replicating the experimental results.

Novel analytical tools 

“Our study provides a novel version of the Barnes maze and analytical tools that have allowed us to track the repertoire of navigation strategies in mice over time,” said study senior author Sébastien Royer. 

“These tools could be combined in the future with optogenetic and/or pharmacogenetic approaches to investigate the neural mechanisms underlying strategy selection in a given environment.”

The eLife editors emphasize the importance of further investigating how strategy development varies among individual mice. 

Implications of the study 

By analyzing changes in strategy over time for each mouse and comparing the population average, it may be possible to unlock deeper insights into these fascinating processes.

The results of the study provide a new perspective on the age-old question of animal navigation. 

The findings also equip scientists with cutting-edge tools to probe deeper into the neural pathways that guide these decisions. The applications of this research could extend into areas such as artificial intelligence, robotics, and even human cognition. 

More about animal navigation 

Animal navigation refers to the ability of animals to find their way across unfamiliar terrains. Many animals can accurately navigate over long distances. This capability is crucial for activities such as migration, foraging, and territory establishment. 

Mechanisms and cues used for animal navigation

Magnetic compass

Some animals, like certain birds and sea turtles, can sense the Earth’s magnetic field and use it as a compass. This is particularly useful during long-distance migrations.

Sun compass

Animals like bees and birds can use the position of the sun in the sky as a directional guide. They compensate for the movement of the sun across the sky using their internal biological clock.

Polarized light

Some insects, like ants and bees, can detect polarized light patterns in the sky, which they use for orientation.

Star navigation

Certain nocturnal animals, especially some birds, navigate by the stars. The North Star, for instance, offers a fixed point of reference in the Northern Hemisphere.

Landmarks

Familiar physical features in the environment (like mountains, rivers, or trees) can be used as reference points.

Olfactory cues

Some animals, such as salmon, use their sense of smell to return to their birthplace to reproduce. They can detect specific chemical signatures in the water.

Infrasound

Elephants and certain birds might use infrasound (low-frequency sound waves) to navigate, picking up cues from distant sources like the ocean.

Social learning

Some animals learn routes and landmarks by following older, more experienced individuals.

Geometric path integration

Certain insects, like desert ants, keep track of the direction and distance they have traveled from a starting point, allowing them to return directly to it.

Visual maps

Pigeons, for example, are believed to create visual maps based on their surroundings, which they use for navigation.

Each species may rely on one or a combination of these methods, depending on its specific needs, environment, and evolutionary history. 

The study of animal navigation provides insights not only into the amazing capabilities of animals but also into potential technologies and systems humans might develop for navigation.

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