Researchers find evidence that 'humans can sense the Earth's magnetic field'
Geomagnetism is the magnetic field generated by the core inside the earth, and the south pole side is the north pole and the north pole side is the south pole. Some animals have been known to sense and use geomagnetism, but so far it has not been clear whether humans can sense magnetic fields. California Institute of Technology is a biology and biological engineering department professor of Shimojo, Shinsuke research team of Mr. et al., Conducted an experiment to change the magnetic field while observing the human brain waves, finding evidence that 'human beings can sense the magnetic field.' Announced it was
Transduction of the Geomagnetic Field as Evidence from Alpha-band Activity in the Human Brain | eNeuro
New evidence for a human magnetic sense that lets your brain detect the Earth's magnetic field
Scientists Find Evidence That Your Brain Can Sense Earth's Magnetic Field
The north pole of the compass points north because of the function of the earth's magnetism, but the earth's magnetism is quite weak on the surface of the earth, and it has only about one-hundredth of the magnetic force of a magnet stuck to a refrigerator. However, there are animals on earth that feel the magnetic field and use them for navigation. For example, animals such as migratory birds and sea turtles use the earth's magnetic field to determine direction and location.
The loggerhead chooses a beach with a 'magnetic field' similar to the beach on which it was born as a spawning site-GIGAZINE
On the other hand, the question of whether humans can sense magnetic fields has not been answered for many years. Some of the positive results and negative results of the theory that human beings can sense magnetic fields, and for decades have not seen consensus.
The research team believes that for a long time no human opinion on the magnetic field sensing ability has come to a firm opinion, because much of the past research has relied on 'the everyday human sense'. Almost every human being is not aware of the magnetic field in daily life, and even if the magnetic field affects everyday life, it remains unconscious or very faint. So the research team of Shimogamo et al., Which included biologists and cognitive neurologists, took another approach and tried to discover neuroscientific evidence.
The research team had 34 adult subjects sit in a special Faraday cage surrounded by conductors, closed their eyes, and observed their brain waves. The Faraday cage was constructed to generate a controlled magnetic field by passing a current through the wire, and the research team was able to manipulate the magnetic field in the cage freely. When no special magnetic field was generated in the Faraday cage, a magnetic field equivalent to the position of 60 degrees north where the experiment was conducted was said to be in the cage.
Normally, the direction of the magnetic field changes relative to the brain when people turn their head or turn around in their daily lives. First, when the research team instructed the subjects in the cage in the dark to turn their head slowly, there was no change in the EEG, despite the change in the direction of the relative magnetic field.
Next, with the subject sitting still in the cage, only the magnetic field was changed. A similar change in magnetic field can be obtained by turning the chair in which the subject sits or rotating while riding on a vehicle, but in this case the subject feels 'I am not turning now' to the subject himself there is. In this experiment, without planting such physical sensations, I changed only the magnetic field while sitting in the dark.
As a result, all 34 subjects felt nothing particularly when the magnetic field changed. However, when we observed alpha waves in the brain, it was found that four subjects showed a large decrease in alpha waves when the magnetic field changed. It is known that alpha waves that are often observed when people awake and rest are reduced when they receive strong sensory stimulation, and the reduction of alpha waves observed this time is also strong external It seems to match the pattern when I was stimulated.
The participants showed a reduction in alpha waves only when the vertical magnetic field matched the natural magnetic field at 60 degrees north of the experimental site. In other words, it was confirmed that the alpha wave decreased only in the same magnetic field change as people turned sideways on the spot and replaced the front and back of the body. The alpha wave did not respond to the unnatural direction of the magnetic field change, indicating that the human magnetic field sensing system is shaped and adapted to the natural environment.
In other animals, it is known that 'unnatural magnetic field change' is filtered and not reflected in navigation. Elements such as lightning and other natural phenomena and abnormal magnetic field generation due to geographical conditions are harmful in navigation in the direction, and it is reasonable to exclude such unnatural magnetic field changes. Robin for research in, and magnetic field sensing is increased by more than 25% than usual, Robin is so has been found to stop the use in the navigation of the direction of the magnetic field.
The research team has predicted that it was suggested that only 4 out of 34 people would have magnetic field sensing capabilities. Just as not all people are good at art or mathematics, it is not strange that there is individual difference in magnetic field sensing ability. Connie Wang of the California Institute of Technology, who worked on research, said that the ability of humans to sense magnetic fields is a legacy of those that have evolved in the past.
in Science, Posted by log1h_ik