We got another source-off!!!
Interesting but a little dated wouldn't you say? Anyway, I see no need to defend the opinions of the medical experts quoted in this book by Sinek and if you were to peruse it. You would clearly see that they have substantial credentials and credibility.
The left brain/right brain dynamic is not a new medical discussion. It's been around for quite awhile.
The fact that you're attempting to diminish the credibility of the author because of his vocation rather than his informed knowledge of the topic(from medical experts) is simply.. Left brained.. You're not looking at the Big Picture.
As any good attorney will tell you .If you do enough research on an opinion to support your intended position on behalf of your client, you can find it.
A good mental exercise to expand the plasticity of the brain. Learn.Unlearn.Relearn. Give it a try. Builds new neural pathways.