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[Poopadoop]

I saw people (local skeptics society fb group) discussing the article and claiming that if true, it'd fundamentally change our understanding of how brains work. Apparently something like the neuron signals can't be detected by an outside electromagnetic field measurement, and conversely an outside electromagnetic field cannot affect the signaling. They seem to think this is a big deal.

It might be a big deal for some measures of brain activity that rely on electical-magnetic signals, such as electroencephalography (though that's not a very influential method tbf). And, some means of disrupting brain activity to measure its function rely on introducing localized magnetic fields that disrupt brain activity (e.g., transcranial magnetic stimulation). If this is true, then these methods would not work on myelinated axons, but only on non-myelinated axons, limiting their robustness.

To explain the biology of the cited article a bit, the neurons' main way of communicating with one another involves chemical-electrical signalling. If a neuron's cell body reaches a certain level of electrical polarisation, it causes a chain reaction of chemical-electrical effects in the axon, which flows as a wave of changes in the electrical polarity between the inside vs. outside of the axon, ultimately leading to the release of neurotransmitters that then influence the neuron(s) that cell connects to, and so on.

Myelin is a fatty sheath that coats the axons of some cells, acting as an electrical insulator. When an axon is myelinated, the signal can travel much faster.

https://en.wikipedia.org/wiki/Myelin

A lot of axons have myelin sheaths. In fact, multiple sclerosis is a disease where these sheaths get attacked by the immune system, and the brain eventually stops working because of it. So, they're pretty important.

The cited article seems to suggest (can't really follow the physics) that conventional electrical signalling theory can't explain the speed of transmission through myelinated axons. This, if true, implies as I said that certain conventional magnetic-electrical methods for measuring and/or manipulating brain states are unreliable, or at least are only measuring/manipulating the activity of unmyelinated axons.

Incidentally, fMRI would not be impacted by this because it measures blood flow, not brain activity directly.