I found out about it in this book The Body Keeps the Score[1]. Its a massive book, so I would just focus on the Neurofeedback section. But it doesn't have the first hand experience so mileage may vary.
By co-incidence the researcher that pioneered this breakthrough treatment was located in the same city as me. You can see some of the videos[2], but it will be difficult to understand and appreciate unless you spend a lot of time reading papers and learning about the brain. I will say its worth it to learn, especially if you want your ability to focus to go from below average to far above average. Feel free to email me if you want details, I had to become well versed at it out of necessity more than anything.
