Washington: Certain neurons in pigeon brains encode the direction and intensity of Earth`s magnetic field, providing the common birds with an internal global positioning system (GPS), a new study has claimed.
According to the study, birds and other organisms, such as bees and turtles, likely possess similar systems, but humans are not likely to possess a magnetic sense of direction, although they can map out shorter distances in their heads.
“We have found cells in the (pigeon) brain that signal the direction, intensity and polarity of an applied magnetic field,” Discovery News quoted David Dickman, co-author of the study from Baylor College of Medicine neuroscientist, as saying.
“These three qualities can be used by the brain to compute heading information, like a compass, and latitude on the Earth surface (location between the magnetic North and South Poles).
“It is possible that magnetic intensity could also be used to give the bird longitude (East-West location) through learned associations of differing regional variations along the Earth surface.
“Together, these cells could form the basis of determining heading direction and position according to a brain representation of a magnetic Earth surface map,” he said.
For the study, Dickman and his colleague Le-Qing Wu placed 7 pigeons in a pitch-black room and used a 3D coil system to cancel out the planet`s natural geomagnetic field and generate a tunable, artificial magnetic field inside the room.
While they adjusted the elevation angles and magnitude of their artificial magnetic field, they simultaneously recorded the activity of neurons in the pigeons` brains that had already been identified as candidates for processing such magnetic signals.
They identified 53 specific brain stem neurons that exhibited significant responses to changes in their artificial magnetic field.
Prior research found that magnetic receptors in the retina, nose, inner ear and possibly the beak of birds receive and interpret magnetic field information, which then goes to the brain for processing.
In addition to the findings applying to other birds, they could also apply to bacteria, honeybees, fish, turtles and even a few mammals, such as the blind mole rat. All of these organisms are documented as being able to sense and use the Earth`s magnetic field.
In the case of pigeons, the ability allows them to travel hundreds of miles. Dickman reminded that “the ancient Romans used pigeons to carry messages home from their battles.”
Up to a certain point, the GPS is useful, but when honing in on a specific location, he believes pigeons rely more upon other orientation cues, such as vision and smell.
The study has been published in Science Express.