Pulsed refers to the length of time the ultrasound was active. I believe in this experiment the pulse was the length of mere milliseconds, or less, but it should specify the length in the study. So the ultrasonic frequency has nothing to do with the pulse length. This is important since the focused vibrations generate heat, and consequently can damage tissue if it becomes exposed for too long (higher ultrasonic frequencies and higher amplitudes [power] are actually used to destroy tissues within the body).

I'm thinking the effects of neural excitation had lasted longer than the actual pulse length, but how long this latent effect lasted I'm not clear on.

And I do believe I read that they had, in fact, used pulsed ultrasound at a variety of pulse lengths.