If they can do this in RF frequencies to which our bodies are opaque, how long before they can do this in RF frequencies to which our bodies are transparent?
If a frequency has to go right through you without loosing energy, then none of the energy can be put in to modifying neurons. Of course, you could do like they do with radiation therapy and have lots of low-absorption beams converge on a single spot.
They can't. An RF antenna for useful wavelengths is much bigger than the size of the proteins you can genetically engineer. We CAN engineer proteins sensitive to light (eg: use the ones that are already present in your retina, and connect them to an ion channel typically found in a neuron). What you're proposing is not simple (though WOULD be immensely helpful for neuroscience research...)
