Bulletproof Radio welcomes scientist Dr. Stephen Porges back to the show. He's known for his deep and profound understanding of the human nervous system and its application to real-life clinical settings.Dr. Porges created the Polyvagal Theory, which explains the workings of the vagal nerve and links the evolution of the mammalian autonomic nervous system to social behavior. He has authored and co-authored several books on the subject. For 25 years, his Polyvagal Theory has been leading to innovative treatments based on insights into the mechanisms mediating symptoms observed in behavioral, psychiatric, and physical disorders.One of my favorite episodes of Bulletproof Radio was #264 when he and I talked about this theory. I encourage you to listen to that episode and check out the two Bulletproof Blog articles. I was so impressed with his research that I included it in my new book Game Changers, specifically Law #44, which is “Gratitude is Stronger than Fear.”Dr. Porges also is the creator of a music-based intervention, the Safe and Sound Protocol™, which currently is used by more than 1200 therapists to improve spontaneous social engagement, to reduce hearing sensitivities, and to improve language processing, state regulation, and spontaneous social engagement.In this new episode, we explore how sound, safety, environment and gratitude are all intimately connected to our nervous system circuitry.“Your body, in safe environments, will start to spontaneously optimize those circuits,” explains Dr. Porges. “We need to structure narratives that have a degree of positivity, so that our nervous system doesn't feel too scared to evaluate it.”We’ll be making links between Dr. Stephen’s work and fascinating brain-body interactions, often deeply rooted in our ancient biology. We introduce “neuroception,” find out how to structure environments for those who struggle with sensory processing issues, better understand how hearing frequencies affect adults and kids differently, and learn how to control our own heart rate variability.