Quantifying brain activity using EEG

What are the different ways to measure/quantify changes in brain activity before and after some form of therapy? I am currently looking at desynchronization, power spectral analysis, and correlation between regions (for connectivity).

I was going to focus on the beta band range of 13-30Hz.

hmm, there must be dozens of ways. Power and synchronization are certainty two sets of features that people often analyze. Perhaps it will be useful to look through the literature and see what kinds of analyses other people have applied to the kind of therapy you’re looking at.