With mindmapping, most of it can be done from the Table of Contents. An alternative method to having a "pretty" mindmap is to just write whatever words and draw whatever pictures come to mind without using the book as reference. Then, draw lines when you're done writing.

Mostly, the mind-map isn't an activation technique so much as a retention technique. By getting other areas of the brain involved, you make the information more available to you after-the-fact.