New research has showed that the individual neurons in the brains of common pigeons could relay crucial information about the Earth’s magnetic field, potentially providing these animals with an internal GPS.
The research in magnetoreception was published in the journal Science, and it shows that individual cells seem to encode information on a magnetic field’s direction, intensity, and polarity. The common pigeon of the family Columbidae in the order of Columbiformes has always been able to perform remarkable navigation feats, which were always thought to be down to the fact that the animals sensed magnetic fields, but scientists trying to prove this were frustrated for years.
The new work suggests that these signals are part of the inner ear, called the lagena, which complicates matters further for field researchers. It was previously thought that the birds used magnetic sensors located in their eyes and beak to navigate. However last year, it was reported by David Dickman and Le-Quing Wu that the birds’ magnetoreception was linked to the lagena.
Wu and Dickman used homing pigeons (Columba livia), placed them in a dark room, and generated a magnetic field to cancel out Earth’s field. Researchers monitored the birds’ brain activity, while rotating artificially created magnetic fields around the pigeons.
Vestibular neurons, linked to balance systems in the inner ear, fired differentially in response to the alterations in the field’s direction, intensity, and polarity. These cells were particularly sensitive to the bandwidth that is used by Earth’s geomagnetic field.
The birds combine this information and it could provide them with more than just a compass heading. It could be used for positional and directional information. This doesn’t mean that there aren’t any magnetoreceptors in the beak region. There is mounting evidence linking the ability to this region of the birds’ bodies.
Now, researchers will have to test their findings experimentally to confirm that the lagena is responsible for the birds’ magnetic sense.
Reference: “Neural Correlates of a Magnetic Sense” by Le-Qing Wu and J. David Dickman, 26 April 2012, Science.