Researchers at Caltech seated volunteers in a dark, electrically shielded chamber wrapped in coils that could reproduce Earth-strength magnetic fields and rotate them in controlled directions, then recorded brain activity with EEG while the field direction changed around each person.
When the magnetic field was rotated in certain directions, a specific brain wave pattern called alpha-band activity dropped sharply and consistently, a response known as alpha event-related desynchronization that typically shows up when the brain processes an incoming sensory signal. The drop appeared reliably across repeated trials in some participants.
The effect only appeared for certain rotation directions relative to the field's vertical component matching conditions found in the Northern Hemisphere, suggesting a biological response tuned to local geomagnetic conditions rather than a generic effect of any magnetic field. Responses varied considerably between individual participants, and the biological mechanism, whether built on magnetic particles in cells or some other process, is still unidentified years after the result was first reported.
Read the original study
Wang et al., eNeuro, 2019 · doi.org/10.1523/ENEURO.0483-18.2019
A compass needle, hidden somewhere in the human brain.
Source
- Wang, C. X., Hilburn, I. A., Wu, D.-A., Mizuhara, Y., Cousté, C. P., Abrahams, J. N. H., Bernstein, S. E., Matani, A., Shimojo, S., & Kirschvink, J. L. (2019). Transduction of the Geomagnetic Field as Evidenced from alpha-Band Activity in the Human Brain. eNeuro, 6(2). https://doi.org/10.1523/ENEURO.0483-18.2019