But the real question was,"What was the mechanism?" And so my work, actually following grad school, was first to develop techniques to quantify physiology. Second, to see how physiology was related to behavior. Third, was it the individual difference? And then fourth was the real discovery or real journey, and what does it all mean? When you measure and you have these biomarkers, what does it really tell you? What are those measures related to in terms of their mechanisms? So, so much of modern psychology and psychiatry is all about biomarkers or correlates. I was interested in the mechanisms, and what I did was start to literally discover the unique neural mechanisms underlying the regulation of heart rate, and that became the Polyvagal Theory.
Eric: That's great, that's great. And I understand that the Polyvagal Theory has a lot of impact on social bonding theories, and if you could tell us a little bit about that?
Dr. Porges: Well, we actually have to go back and unpack what the Polyvagal Theory is all about. The Polyvagal Theory really was a response to a paradox that I observed when I was doing research. I was studying human newborn babies and actually human fetuses during delivery, and I was trying to develop a technique to monitor well-being. And I was measuring heart rate and heart rate variability, and I ran into this basic paradox, that healthy babies had a lot of heart rate variability, and I had assumed that the variability was being mediated through a cranial nerve called the vagus. So in a sense, more brain to heart communication gave you more heart rate variability, healthier babies.
However, when the major risk factors during delivery and also during the neonatal period is clinical bradycardia, that's when the heart rate slows up a lot. And within the medical community, that was also viewed as a vagal response, and that didn't make any sense to me. How could the vagus both be protector and literally destroyer? How could the vagus protect us from insults and problems, yet be the marker of the insult itself? And that led to a real personal journey of both research and literature review.
And that ended up with, as the Polyvagal Theory, which basically said, "Yeah, we have two vagal systems." One, we inherited from more primitive vertebrates, like what reptiles do. When they're under stress or scared, they immobilize, they become inanimate. And so, that's a vagal response of heart rate slowing up, because they reduce metabolic activity. They could go underwater for a couple hours, but mammals need lots of oxygen. They don't have the privilege that a reptile has, which is shutting down. And they have a newer vagus, and that vagus is linked.
Eric: That's great, that's great. And I understand that the Polyvagal Theory has a lot of impact on social bonding theories, and if you could tell us a little bit about that?
Dr. Porges: Well, we actually have to go back and unpack what the Polyvagal Theory is all about. The Polyvagal Theory really was a response to a paradox that I observed when I was doing research. I was studying human newborn babies and actually human fetuses during delivery, and I was trying to develop a technique to monitor well-being. And I was measuring heart rate and heart rate variability, and I ran into this basic paradox, that healthy babies had a lot of heart rate variability, and I had assumed that the variability was being mediated through a cranial nerve called the vagus. So in a sense, more brain to heart communication gave you more heart rate variability, healthier babies.
However, when the major risk factors during delivery and also during the neonatal period is clinical bradycardia, that's when the heart rate slows up a lot. And within the medical community, that was also viewed as a vagal response, and that didn't make any sense to me. How could the vagus both be protector and literally destroyer? How could the vagus protect us from insults and problems, yet be the marker of the insult itself? And that led to a real personal journey of both research and literature review.
And that ended up with, as the Polyvagal Theory, which basically said, "Yeah, we have two vagal systems." One, we inherited from more primitive vertebrates, like what reptiles do. When they're under stress or scared, they immobilize, they become inanimate. And so, that's a vagal response of heart rate slowing up, because they reduce metabolic activity. They could go underwater for a couple hours, but mammals need lots of oxygen. They don't have the privilege that a reptile has, which is shutting down. And they have a newer vagus, and that vagus is linked.
