We're still working on understad how animals detect magnetic fields, but what's going on in their brains to make sense of it all? Researchers have discovered the part of pigeon's brain that can process magnetic signals they detect, and it's enough to direct them travelling across the globe.
How do you find out what's going on in a pigeon's brain, anyhow? Researchers at Baylor College of Medicine created a dark room with a three-dimensional coil system, that allowed them to cancel the Earth's natural magnetic field, and create their own customized one on demand. By recording neuronal activity in the birds while changing the magnetic field, the researchers discovered how the brain decodes magnetic fields.
What they found is some 53 vestibular brainstem neurons that react to the magnetic field, and encode the direction, intensity, and polarity of a magnetic field. These neurons were the most responsive within the intensity range of the Earth's magnetic field, and from all this information, the birds could navigate. In the paper, the researchers conclude:
We suggest that MR cells encode a geomagnetic vector that could be used by the neural population to computationally derive the bird's position and directional heading. The geomagnetic vector elevation component could provide the bird's latitude, the vector azimuth component could be used as a magnetic compass to provide heading direction, and the vector magnitude could provide spatial position cues through local variations in intensity relative to a learned internal model of geomagnetic space.
While there's still much to be done with deciphering the specifics of how magnetoreception works, this shows how the underlying part of the brain handles it.
Photo by Phineas Jones.