Pigeon Brain's Global Positioning System

'GPS maps' found in pigeons' brains | TG Daily

Researchers at Baylor College of Medicine say they've discovered how certain brain cells encode the direction and intensity of the Earth’s magnetic field.

Pigeon brain's global positioning system located - life - 27 April 2012 - New Scientist

Pigeons could tell when the magnetic field was flipped, so they avoid flying in the wrong direction (Image: Carl de Souza/AFP/Getty Images)

David Dickman and Le-Qing Wu of Baylor College in Houston, Texas, collected seven homing pigeons (Columba livia) and inserted electrodes into their brains to record the activity of individual neurons.
They then placed the birds inside an artificial magnetic field, which masked the Earth's usual magnetism. The room was completely dark to prevent the birds using visual signals to orient themselves. As the researchers adjusted the intensity and angle of the magnets, they monitored how the pigeons' brain activity changed.

Built-in GPS in birds in tune with Earth's magnetic field - Baylor College of Medicine

Neurons play role

"We know birds and many other animals can sense the magnetic force; behavioral studies show that birds fly along magnetic routes during seasonal changes," said Dickman, who conducted much of the research at Washington University in St. Louis. "It is still unknown what exactly acts as a receptor within the bird; however, in our current study we are able to show how neurons in the pigeon’s brain encode magnetic field direction and intensity. This is how we believe birds know their position on the surface of the Earth."

Dickman said certain areas of the brain are activated when a particular area of the inner ear, known as the lagena, is exposed to a magnetic field. Without it, several of these corresponding areas in the brain show no activity.

Dickman and Wu used electrodes in one brain area, known as the vestibular nuclei, to record activity when the bird was exposed to a changing magnetic field.

"The cells responded to the angle and intensity of the magnetic field. Some cells were more sensitive depending on what direction we aimed the magnetic field around the bird’s head," Dickman said.

Global Pigeoning System - ScienceNOW

In the new study, published online today in Science, Dickman and BCM biologist Le-Qing Wu placed seven homing pigeons (Columba livia) in a dark room in the center of a cube-shaped set of magnetic coils. As the cube was rotated, the intensity of the magnetic field felt by the pigeon in the center varied. The scientists turned it in every direction, testing out the effect of various magnetic fields found on Earth. As they did this, Dickman followed the activity of 329 neurons in one of the areas of the brain he'd previously implicated. Fifty-three of the brain cells showed significant changes in activity as the coils rotated, reacting to field strength and polarity. The properties of the neurons allow them to have a unique activity pattern for every different spot on Earth, the scientists realized. Not only can the neurons allow the pigeons to pinpoint their longitude and latitude, says Dickman, but they can differentiate the Northern Hemisphere from the Southern Hemisphere and tell the pigeons which direction they're facing.