I've been reading about Transcranial Magnetic Stimulation (TMS) which can activate neurons using a magnetic field, which got me thinking... what if we can pick and choose exactly which neurons to activate? Then we'd be able to create true non-invasive in-brain virtual reality.
For that to be possible, we'd need to be able to make a magnetic field of any shape, probably by combining the magnetic fields of hundreds of different electromagnets and having them "sum" to the final desired vector field...
Also, we would have to be able to pick and choose the "dead zones" so we don't stimulate every single neuron within range. Are there even dead zones in magnetic fields? Is this possible?