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"He sticks the anode - the positive pole of the battery - to my temple, and the cathode to my left arm" Does this even make sense physically? I mean, wouldn't
by Tichy 15y ago
"He sticks the anode - the positive pole of the battery - to my temple, and the cathode to my left arm"
Does this even make sense physically? I mean, wouldn't the skull work a bit like a Faraday cage, not allowing any currents into the brain?
I am highly sceptic of this new hype.
- jonnathanson 15y agoI have no idea about the placements on the temple and left arm, but left-temple / right-temple placements are basically how electroconvulsive ("electroshock") therapy works (in that case, the current is used to generate seizures). I'm not a doctor, but as far as I understand, the human body is highly conductive -- and there are a number of "wires" and conductive fluids running into and out of the brain. The entire nervous system is, in a very rough sense, electrochemical circuitry.
- adient 15y agoModern ECT would be performed on only the right side of your brain, with one electrode on the temple and one slightly offcenter at the top of your head.
- kghose 15y agoYou may be imagining dead bone, like that in displayed skeletons. Bone, in our bodies, is alive. It has blood vessels, it regenerates and can have innervation. Such bone has conduction channels. But it is true. I don't know what the current paths are - but to activate neurons very tiny current densities are needed, so probably even though the bulk of the current flows along the skin, the little that leaks into the brain is probably what is cause whatever effects are seen.
- blrgeek 15y agoFaraday's cage needs to be made of highly conductive material, like sheet metal, or metal wire. Bone is quite resistive, and would be quite transparent to electricity. Second, blood (salts/water) makes for a nice conductor.
- Tichy 15y agoYeah I thought that maybe the bone of the skull insulates, but it is covered in blood vessels that form the cage.
- MaysonL 15y agoGiven that EEGs record currents from the brain, I see no reason that similarly (even differently) place electrodes would cause current flow to the brain.
- demallien 15y agoI missed the party, but I thought you might find the following useful. A Faraday cage is impervious to electromagnetic waves. It is not impervious to an electrical current. Or rather, if you apply two electrodes with a voltage difference on the Faraday cage, you will get a current flowing between the two electrodes (for a perfect Faraday cage, with a resistance of zero, and a perfect voltage supply, the current would be infinite!). Someone inside the Faraday cage equipped with a multimeter would be able to see this current, which in a real-world Faraday cage will flow along the shortest path between the two electrodes. If you vary that current over time, you will induce electromagnetic waves on the inside of the Faraday cage - indeed you have just turned your Faraday cage into an antenna. This is pretty much what was being done in the New Scientist article...