Does anyone know, how does the strength of these fields compare to the strength of the field in the brain from a wifi router at a reasonable distance? Why doesn’t all the comms gear mess with our thought processes?
as this study shows, as well as others, electric fields do "mess up" with individual synaptic transmission. nature has evolved action potentials as a reliable way to propagate signals in the presence of the myriad sources of electromagnetic radiation on earth. They can be disrupted by appropriately high stimulation such as with TMS . Most likely, the radiation sources that we use every day, phones computers etc do have some effect in neurotransmission but those random failures are probably too few (and too random) to matter significantly or systematically.
Neuroscience PhD student here. The skull acts as a low-pass filter. EEG recordings are typically low pass filtered at 70Hz or lower for example. This is why you can’t decode eg speech from a EEG: the neural encoding is at a higher frequency band than can be recorded. Even though the signal is much stronger, digital comms equipment is orders of magnitude higher in frequency and does not penetrate the skull well.
fMRIs use a crazy strong magnetic field—typically >= 3 Tesla. The signal that is measured is not electrical but rather the blood oxygen level. Effectively, this is a correlate of the metabolic expenditure of nearby neurons. Wass it is also like a low-pass filter except here it’s more like 0.5 Hz or slower. On the plus, you get much improved spatial resolution
MRIs use two magnetic fields, a static one and a dynamic one. And they use a radio signal according to the larmor frequency to excite the spin of the atoms. I was wondering about that radio signal component.
This has very little relevance to the topic at hand as these refer to electroencephalogram measurements taken through a skin (scalp) patch and conductive gel.
Empirically, we'd want data on how corresponding electromagnetic pulses would affect brain activity -- there should be resonance effects, once the amplitude is high enough.
