Where did you grow up?
I grew up in Eunice, Louisiana, deep in the heart of Cajun country, and ground zero for Cajun music.
At what age did you become aware of the uniqueness of Cajun music?
The uniqueness, I didn't know. That was just what was there. No matter where I went, we had some Cajun music playing. It was part of the culture, so much that I didn't even notice it.
Were you listening to the radio?
Yeah, whatever was on. In a small town like that, you'd have a radio station that's catering to a lot of different groups. After school, they'd play Elvis Presley, Buddy Holly, or something of interest to teens. In the evening, it turned more towards soul and rhythm and blues. I loved pop music. I could pick up WLS in Chicago and other long-distance stations, including some in Mexico.
Did you have an interest in science as a child?
Absolutely not. Science wasn't on my radar. I was taught by nuns in Catholic school, and they were putting me into the priest boot camp trajectory. Kind of an anti-science environment! [laughter] In high school, we got folk guitars, because that's what was happening in the early '60s. We were playing Simon & Garfunkel and Peter, Paul and Mary. It was a good way to hang out with girls. Then, by February of '64, The Beatles had arrived. Everybody threw those acoustic guitars away and ordered Sears, Roebuck & Co. [electric] guitars. I still have my Silvertone and my Fender Deluxe amp. And I was in bands, and I was a disc jockey in high school.
Music is in your soul and your body.
It is. It's what I cared about most as a kid. Then it was time for me to go to college. The year that I graduated, a junior college opened up in Eunice. I got a degree in business administration, and I got interested in consumer protection. This was during the time of Ralph Nader, and I was into consumer psychology. Later, I started a master's in marketing back at LSU [Louisiana State University] in Baton Rouge. I got more and more interested in psychology, and I was taking a lot of psychology courses.
You studied psychology through marketing?
Exactly. Near the end of my master's work, I took a class on learning and motivation. It was all about the brain mechanisms of learning in rats. That's what the professor researched. I didn't even know you could study the brain. I asked if I could work in his lab and he said, "Sure." We published a paper or two together, and I applied to PhD programs in psychology and the brain. I had no credentials, but I applied to a dozen places. [State University of New York at] Stony Brook, out on Long Island, accepted me. I got in there and met my mentor, Michael Gazzaniga, who was studying split-brain patients, which I had not even heard of at that time.
What is split-brain?
There are some people who have epilepsy that is so bad that it can't be controlled by medications. Back in the '60s and '70s, when all of this was being done, the medications were not very good. Kids that had epilepsy from an early age could have seizures so bad that their parents had to hold them on mattresses. It was awful. A last-ditch effort, not something that they would ordinarily do, was a dissection of the connections between the two sides of the brain. It prevented the seizures from bouncing around from side to side and being more harmful than they would otherwise be. What was interesting in these people were the psychological implications. In most people, language is on the left side of the brain, so that side of the brain in a split-brain patient can talk and respond and knows who they are. There's a conscious human person there. On the right side is a different story. The left hand, connected to the right hemisphere, can reach into a bag or point to a picture and non-verbally indicate what it saw, but it can't talk to you. It's not clear who's living over there, if anybody.
It's more reflexive?
I wouldn't call it reflexive. It's more that the right hemisphere knows what things are and can respond to them non-verbally. I did my dissertation on a patient who was unique. Like most of us, this guy had the normal language skills in his left hemisphere, but we discovered that his right hemisphere could read, even though it couldn't talk. That was the opportunity to ask interesting questions by putting words into his right hemisphere. If you're staring at a dot on a screen in front of you, and a stimulus appears on the left side of that dot, that stimulus goes to your right hemisphere. Similarly, a stimulus to the right of the dot goes to your left hemisphere. In most people, the two processes merge. What the right side sees goes to the left, and what the left side sees goes to the right – that's what those connections between the two sides are for. Normally, we don't have a left and a right world; it's just one world. It's like an illusion that's been put together by the brain. In the split-brain patient, who doesn't have the ability for the info to cross from one side to the other, the info stays there. So, if we put a word like "apple" into the right hemisphere he could select what he saw by selecting an apple from pictures of several objects. This showed that the right hemisphere of this patient could read words and turn those into actions. On the basis of that, we put in the question, "Who are you?" on the left side of screen – to the right hemisphere. The left hand reached into a pile of Scrabble letters and arranged them to spell his name, "Paul." I still get chills thinking about it. That was the first time anyone communicated in a human way with the right hemisphere of a split-brain patient.
That's unbelievable.
We went further. The question was, "What job do you want?" The right hemisphere spelled out "race car driver" with Scrabble letters. The left hemisphere had already told us he wanted to be a draftsman, an architect. The two sides had different ambitions. Same self-identity, Paul, but different ambitions for Paul. But the kicker was a study where each hemisphere saw a different stimulus. The two hands pointed to the appropriate matching picture. When asked, "Why did you pick those?" the left hemisphere, of course, didn't know why the left hand choice was made. But it made up a story, without batting an eye, that made the two pictures go together.
What was the result of those experiments?
The big idea that we had was that a lot of behavior is controlled non-consciously. The conscious brain has to tell itself a story in order to make these unconsciously generated behaviors make sense. This is necessary, because the conscious mind has its own rules, actions, and understanding of the world that doesn't necessarily match with all the unconscious knowledge in the brain. Such stories or narratives are what I have spent much of my career subsequently trying to come to terms with, scientifically.
What came next for you?
After graduate school, I turned to studies of rats to understand systems in the brain that might control behaviors that, in the human brain, might need this justification or rationalization. I decided to study emotional behaviors in rats by giving them a tone, paired with a mild shock, and then the rat would freeze every time it heard the tone. Because the circuits in the human brain that cause us to freeze are the same as those in the rat brain (because of evolution), we can use the rat brain and its control of behavior to understand the control of those systems in the human brain. We can't understand human emotion or human consciousness from rat brains, but we can understand the non-conscious behaviors that go with it. I spent most of my early career mapping out those pathways. What I tried to do in rats was to follow the flow of that auditory-conditioned stimulus, that tone paired with the shock. The tone goes into the ear, then generates a sequence of activity from area to area, and ultimately neural signals come out of the brain, go to the spinal cord, and voila, the rat freezes. This was possible to do because the input (the ear) and the output (the muscles) define the beginning and end of the pathway. And, because the auditory system is well understood, and we know how the motor responses come out of the spinal cord to the muscles, the task was simply one of connecting the neural dots in the brain between the stimulus and the response. That's what I did. In less than a decade, I – and couple of other researchers who were on the same track – were able to map that whole pathway. It didn't hurt that there were brand new techniques that had come out for studying how brain areas connect with one another.
When you say tones, do the various types of tones make a difference? Does this in any way relate to music and the brain?
Well, it does, in the sense that it's a tone. When I chose this particular behavior, I did it for two reasons: One, the stimulus could be very simple. That was important since the goal was not to understand auditory processing per se, but to understand what happens after the auditory system processes it. The second thing was that the response is so reliable. Freezing is an innate response and occurs the same in every rat, and even in every human. Through conditioning, we can couple that innate response to a new stimulus. That's what Pavlovian conditioning is all about. People think it's simple and it doesn't apply to humans, but a lot of what we are is maintained by a history of Pavlovian conditioning. Certainly not everything, but the simple should not be ignored just because there is more complicated stuff going on. It's also important to note that, while rats and people respond similarly, we don't know what's going on mentally in rats. But in the human brain, interpretations and narratives are going on all the time – as the basis of our conscious experiences. I laid the basic findings and ideas out in my book, The Emotional Brain.
That's a famous book.
It's still in print, since 1996. In that book, I describe all of what we've been talking about; all the automatic, reflexive kinds of stuff I was studying through conditioning in rats. But, at the very end, I had a chapter called "Once More With Feelings," which is about how the actual experience comes about, and emphasizing the split-brain idea that Mike and I came up. When we see ourselves behaving in a particular way, we generate that narrative to explain it. Fear, or any emotion, is simply a narrative. It's not an innate response. My work on the amygdala has often been interpreted to mean that the amygdala is the brain's fear center. That's wrong. What the amygdala does is detect and respond to danger. Your prefrontal cortex, the most advanced part of your brain, is spinning those narratives and telling those tales. That's what the emotion is: The telling of a tale to yourself about what is happening to you. This is based on what's called the schema, a body of knowledge.
That one has acquired?
That they've acquired about situations. These schema are unconscious or non-conscious templates out of which the narrative flows, given all the other things going on at that moment. The narrative itself is unconscious, but it's what you become conscious of. Ultimately, that's what all my books have been about. I never got back to your question about the stimulus tone. I wanted a simple stimulus. The pathway ended up going through this part of the brain called the amygdala that I had worked on for so long, but I didn't know that's where it was going to go. The amygdala had been implicated in fear much earlier, but it was just kind of like a piece of meat in the brain that did something. It wasn't like we knew the inputs and the outputs and how it all worked. That's what I was able to help contribute to – the inputs and outputs, as well as the cells and synapses and molecules that make it do what it does. I didn't want anything that would slow the stimulus down in the auditory system and interfere with it getting to the right part of the brain, which turned out to be the amygdala, but I didn't know that at first.
Was it a certain frequency?
It was 1000 hertz. I found out later, too late to reverse it, but rats don't hear 1000 hertz that well! They are high-frequency animals and can hear ultrasounds a 60 kHz or so, which is out of the range of their predators. It's like a secret code they can use to warn each other in danger. Later I used 10 kHz; sounds which are more in their range, but it didn't matter. A 1 kHz turned out to be good enough for what we were doing. Anyway, pure tones are not typically part of everyday life. We hear all kinds of much more complex sounds. But all of those are composed of those simple tones. One thing I should mention about all this is that one of my early discoveries was that when a tone comes into your ear, it was long believed that in order to have any meaningful psychological impact that it had to go to your auditory cortex. You have a visual cortex, an auditory cortex, and so on. Those are the receptive areas for sensory information, and they do all the meaningful processing, or so it was thought. To get to the amygdala, or wherever else it was going, it had to go through the auditory cortex. What I found in the rats was after I removed the auditory cortex, they could still be conditioned. How was that happening? It wasn't going through the auditory cortex since that was gone. With these new pathway-tracing techniques, I was able to show that the way station before the auditory cortex, the so-called auditory thalamus, not only projects to the auditory cortex but also projects to the amygdala. That's how the amygdala came into the picture. What is that thalamic input to the amygdala doing? It's carrying very simple kinds of quick and dirty signals. A pure tone was a perfect choice, because it could get to the amygdala in 12 milliseconds in the rat brain. That's fast!
Yes, very fast.
It takes about 20 milliseconds to get to the amygdala via the auditory cortex. So what? It's only a few milliseconds slower than from the thalamus to the amygdala. But the brain ticks in milliseconds and the mind ticks in seconds. So, a few milliseconds is a big deal in the brain. The pure tone gets to the amygdala, triggers the response, freezing the blood pressure or heart rate, whatever we're measuring at the time, and, more slowly, goes to the auditory cortex. From there, it sends the amygdala a more elaborate representation. I called these the low road and the high road. The way to think about it is you're walking through a field and, all of a sudden, you find yourself freezing to a stick on the ground because the stimulus went to your visual thalamus and directly to your amygdala. The amygdala detected the stick as a snake, and you froze. It also goes to your auditory cortex, from which it's also getting to the amygdala. This high has more detailed information, telling the amygdala, "That's a stick, not a snake." So, you keep on walking. But if it was a snake, you've frozen and not stepped on it, and your life was saved. It's evolution doing the thinking for you. It's better to treat a stick as a snake than to ignore it and treat the snake as a stick. But, of course, that's not the only way we respond. So much of our emotions are these prefrontal cortex interpretations based on memory, based on the situation, based on the schema, and all that. One thing that might be of interest in the two roads idea is that sounds are processed in multiple ways, and some simple sound changes, like note duration or intensity, might impact the listener a little faster than more complex sounds.
During your research of everything we've discussed so far, was your guitar handy?
It was locked away in the closet. We get involved in a career, right? I didn't have time for music. I was married and had children. Going to meetings and conferences and raising children takes time. By 2006, one of our kids had died from a heroin overdose. That flipped my perspective completely. I had to figure out what's meaningful in life. For his memorial service, I wrote a song about him and played it. I found that to be helpful to the healing. I started playing guitar with a colleague at NYU, Tyler Volk. We ended up forming a band, The Amygdaloids. It was then that I figured out I could write songs that fit my vocal range and write music that fit my level of dexterity. I'm happy with what I've been able to do.
During this time, you were a professor at NYU?
Yeah, I became a professor at NYU in 1989. Before that, I'd been at Cornell Medical College [now Weill Cornell Medicine] for a dozen years, doing research. Then I started writing books that appealed to the public. There weren't many scientists writing books for the lay public in the mid '90s, because it was kind of frowned upon to do those. But my mentor, Mike Gazzaniga, was doing it, and he encouraged me to do it. There were also a few other scientists doing it. By '96, I had written The Emotional Brain.
Your book, The Deep History of Ourselves [: The Four-Billion-Year Story of How We Got Conscious Brains], is on my desk right now. It's a lot.
Four billion years is too much to throw at anyone. [laughter]
But it's fascinating to me.
I like to communicate with the public. I try to come up with ideas that are about who we are and what's happening in our lives.
How did The Amygdaloids form?
