People have actually used infrared to stimulate neurons directly. The mechanism is a little weird, and may be a combination of direct heating (e.g., causing chemical reactions to run faster) and activation of temperature-dependent ion channels.

https://www.sciencedirect.com/science/article/pii/S105381191...

Radio is probably much too fast--the time constant of a neuron is on the order of 10ms, so unless you're pumping a lot of instantaneous power into the neuron, the net effect is likely to be zero.