Researchers observed a 3-D compass in bats' brains that is similar to the mechanism that gives humans their natural sense of direction.
The research team found the brains of bats contain neurons that can sense which way their heads are pointing, potentially allowing them to navigate 3-D space, Weizmann Institute of Science reported. This is the first time a 3-D compass has been seen in a mammalian brain.
To make their findings the researchers developed a tracking apparatus that allowed them to take videos of every angle of the bats' head rotation during flight. They also looked at the bats' neuronal activity using implanted microelectrodes. The observations showed neurons in a sub-region of hippocampal formation are in tune with a specific 3-D angle of the head; these neurons would be activated if the mammal tilted its head a certain way.
The study also revealed for the first time how the brain processes vertical directional information and integrates it with horizontal stimuli. These directions were found to be calculated separately in the brain and cells in different regions of the hippocampal formation depending on which direction was sensed.
By looking at upside-down bats the team determined how the head-direction signals are computed in the brain. They found the lying mammals employ a complex system of mathematical coordinates to orient themselves in space and determine whether they are pointing their heads up or down.
The findings back up the idea head-direction cells in the hippocampal formation act as a 3-D compass that allows people and animals to sense which direction they are going in. Even though the phenomenon has only been tested in bats, researchers believe it exists in a number of non-flying mammals such as squirrels and monkeys.
"Now this blueprint can be applied to other species that experience 3-D in a more limited sense," said Professor May-Britt Moser, one of the 2014 Nobel laureate.
The findings were published in a recent edition of the journal Nature.
