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Scientists find 3D compass in the brain

Staff writer |
Scientists have recently demonstrated the existence of 3D compass in the brains of mammals for the first time.

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Pilots are trained to guard against vertigo: a sudden loss of the sense of vertical direction that renders them unable to tell “up” from “down” and sometimes even leads to crashes.

Coming up out of a subway station can produce similar confusion: For a few moments, you are unsure which way to go, until regaining your sense of direction. In both cases, the disorientation is thought to be caused by a temporary malfunction of a brain circuit that operates as a three-dimensional (3D) compass.

Weizmann Institute scientists have shown that the brains of bats contain neurons that sense which way the bat's head is pointed and could therefore support the animal's navigation in 3D space.

The study also revealed for the first time how the brain computes a sense of the vertical direction, integrating it with the horizontal. It turns out that in the neural compass, these directions are computed separately, at different levels of complexity.

The scientists found that head-direction cells in one region of the hippocampal formation became activated in response to the bat's orientation relative to the horizontal surface, which is, facilitating the animal's orientation in two dimensions, whereas cells responding to the vertical component of the bat's movement, that is, a 3D orientation, were located in another region.

The researchers believe that the 2D head-direction cells could serve for locomotion along surfaces, as happens in humans when driving a car, whereas the 3D cells could be important for complex maneuvers in space, such as climbing tree branches or, in the case of humans, moving through multi-story buildings or piloting an aircraft.

This research supports the idea that head-direction cells in the hippocampal formation serve as a 3D neural compass. Though the study was conducted in bats, the scientists believe their findings should also apply to non-flying mammals, including squirrels and monkeys that jump between tree branches, as well as humans.

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