The ability to sense the Earth's magnetic field-a trait known as magnetoreception-is well-endowed among many animals, but researchers have struggled to show that humans are so capable of the feat. Until now.
eNeuro suggests the human brain is capable of responding to the earth's magnetic field, albeit at an unconscious level. It's not clear if our apparent ability to sense the magnetic field is any useful, as it's likely to be a vestigial on the left of our more primitive past. Giving the new finding, however, researchers should investigate whether or not there is magnetoreception.
Magnetoreception is found between both invertebrates and vertebrates, and it's probably a capacity that's been around for a very long time. Some bacteria and protozoans exhibit magnetoreception, as well as some migratory birds and sea turtles. Dogs are therefore sensitive to the Earth's magnetic field, orienting their bodies along the north-south axis when they poop.
"There is no such thing as 'extra-sensory perception'.
Around 30 years ago, scientists tried to determine if they have a similar capacity, but to no avail. These pioneering efforts have either been inconclusive or unreproducible, so scientists are largely given up, figuring magnetoreception is something outside the human realm. Caltech geophysicist Joseph Kirschvink and neuroscientist Shin Shimojo to revisit the issue.
Kirschvink told Gizmodo "Our approach is to focus on brainwave activity alone". "If the brain is not responding to the magnetic field, then there is no way The brain is first perceive something in order to act on it-there is no such thing as 'extra-sensory perception.' 19659005] Kirschvink and Shimojo set up a rather elaborate experiment in order to filter out any extraneous interference that might influence the results.
The isolated chamber, which had its brainwaves monitored by the electroencephalogram (EEG), was housed inside a Faraday cage, which was shielded from external electromagnetic fields. Three orthogonal sets of square coils, called Merritt coils, allowed the researchers to control the ambient magnetic fields around a participant's head. Acoustic panels on the wall reduced external noise from the building, while a wooden chair and isolated floor avoids any unwanted interference with the magnetic coils. A battery-powered EEG was placed next to the participant, which was connected to an optical fiber cable.
during carefully controlled experiments, participants sat upright in the chair with their heads positioned near the center of the magnetic field, while EEG data was collected from 64 electrodes. The hour-long tests, in which the direction of the magnetic fields were repeated, were performed in total darkness. The experiment involved 34 adult volunteers, who are collectively involved in hundreds of trials; all tests were done in a double blind manner and control groups were included.
After the experiments, none of the participants said they could tell when or any change to the magnetic field had occurred. But for four of the 34 participants, the EEG data told a different story.
As noted in the new study, the researchers recorded "a strong, specific human brain response" to simulate "rotations of Earth-strength magnetic fields." Specifically, the Magnetic stimulation caused a drop in the amplitude of EEG alpha waves between 8 and 13 Hertz-a response shown to be repeatable among those four participants, even months afterward
The alpha rhythm is the dominant brain wave produced by neurons when individuals are not processing any specific sensory information or performing a specific task The drop in alpha waves was observed during the experiments with the brain ields as some kind of stimulus-the neurological purpose or result of which is unclear.
The researchers do not know the human brain is capable of sense magnetic fields, but Kirschvink has a favorite theory. There may be "specialized sensory cells that contain tiny magnetite crystals," he said, which is currently "the only theory that explains all the results, and for which there is direct physiological data in animals." Back in 1992, Kirschvink and his colleagues isolated crystals of biogenic magnetite from human brains, so he may be on something; other researchers should now dive into this possibility to flesh this idea out.
"Kirschvink told Gizmodo." "Magnetoreception is a normal sensory system in animals, just like vision, hearing, touch, taste, smell, gravity, temperature, and many others". "The photon, sound wave, or whatever, and send signals from them to the brain, as well as video camera connected to a computer. But without the software in the computer.
Looking ahead, Kirschvink would like to better understand the biophysics of this capacity, including measuring threshold sensitive. Shimojo believes it could possibly bring magnetoreception into conscious awareness. Imagine, for example, if future humans had a built-in compass, allowing them to sense magnetic north.
Michael Winklhofer of the Institute of Biology and Environmental Sciences, Carl von Ossietzky, University of Oldenburg, liked the new study, saying the authors' did everything to rule out artifacts [noise] changing magnetic field. "Also, the description of the setup and methods so detailed that the study can be easily replicated, he said.
"For the first time in humans, clear responses to magnetic field changes were observed. Even though the magnetic field is not consciously perceived in the test persons [other scientists] to follow the magnetic field elicits neuronal activity, "Winklhofer told Gizmodo.
Biologist Kenneth J. Lohmann from the University of North Carolina at Chapel Hill said it was a "fascinating and provocative study." Given that "a number of other animals can sense Earth's magnetic field, it is certainly within the realm of possibility that humans can as well, "he told Gizmodo.
"It's one thing to find a subtle change in brain activity in response to a weak magnetic field, and another thing to show that people really detect and Use magnetic field information in a meaningful way, "said Lohmann.
Indeed, for now we have the observation that human brains can detect magnetic waves, and leave it at that. Researchers now want to figure out why human magnetoreception exists, and if this capacity somehow extends to our behavior. Regardless, we can look forward to some exciting new science in the future.