The manipulation part is what fascinates me. They didn't just correlate alpha wave frequency with ownership perception. They used transcranial stimulation to artificially speed up or slow down the waves, and the subjective experience changed accordingly. That's a pretty direct causal link between a measurable brain state and something as fundamental as "where does my body end?"
It also makes the self feel uncomfortably fragile
An excellent example of research that maybe shouldn't have been pursued, although it's possible that there are a large number of potential recuperative applications as well that I'm not aware of.