MS. DIANE REHMThanks for joining us. I'm Diane Rehm. Advances in neuroscience point to an ever more complex system, and a system that operates almost completely beneath our consciousness. But in a new book, neuroscientist Michael Gazzaniga argues that not all of our thoughts and actions stem from cell to cell events. He explains why he believes social interaction plays a critical role. His new book is titled "Who's In Charge: Free Will and the Science of the Brain." Michael Gazzaniga joins me in the studio. We do invite your calls, 800-433-8850. Send us your email to drshow@wamu.org. Join us on Facebook or Twitter. Good morning to you, sir. It's good to have you here.

DR. MICHAEL GAZZANIGAGood morning.

REHMI think, for me, the idea I take away from this book is that we do not operate at least within our brains totally independently, that our societal surroundings, the decisions that society makes influence how our brain works. Is that a fair statement?

GAZZANIGAIt's complicated. The point of the book is to, on the one hand, reveal to the reader all we know about the brain, and the view that comes out is the brain works amazingly in automatic ways. It's like your car. We understand how it works.

REHMI don't, but perhaps you do.

GAZZANIGAWe -- some of us do. And so that -- generally people take that and think, well, oh, none of us are responsible for our behavior because it's all done automatically and we're kind of along for the ride, and I say to that, that's not it. You're not getting -- getting it. When you think of the idea of personal responsibility, you look to the social group. You make a deal with the other people that you live in, that you're going to follow a set of rules, and you are capable of following those rules.

GAZZANIGAAnd if you don't have that sort of accountability in a social network, the social network doesn't work, the Internet network doesn't work, no network works without accountability. So to put a -- just a cap on that, think of it this way. If you were the only person on earth, right, there would be no concept of personal responsibility. It comes when there's more than one. It comes as, okay, how are we gonna live together, and there's a set of rules that are externalized, and they're in the ether between you and the next person in the room.

GAZZANIGASo that's where you look for responsibility. You don't look for it as a certain circuit in the brain that if lesion makes you not responsible, that -- that this -- that's not the way to view the matter.

REHMHow much more are we learning about exactly how the brain works?

GAZZANIGAIt's an astounding amount. Last week here in Washington, there were 38,000 neuroscientists coming to sell their wares and show people their latest advancements and everything, and that's a fraction of the number of neuroscientists in the world working on the problem. So there's lots of people, and the advances made every year are -- are large and deep. But my position is that no matter how much we learn, and we gain every year in the details of the mechanism of how the brain works to produce mind, not matter how much we learn, it's never gonna hit that issue, namely that, yeah, but when you think of responsibility that comes out of the social interaction, and that's not something you're gonna unfold or uncover by studying brain to the nth degree.

REHMSo does that separate the notion of the brain from the notion of the mind?

GAZZANIGAWell, in a -- it does, and this is where it gets complicated and we have this seeming conundrum. Most neuroscientists would say that the brain enables the mind. In other words, it's the neuron of the brain that produce the mind. I mean, everybody from Hippocrates forward has pretty much maintained that's the case. And yet the mind, the layer that it produces above it, the mind, can somehow in some way constrain the brain.

GAZZANIGASo what that means is that as you generate beliefs from new experiences that you're having from further education, from your machine, meaning you, just keep going and gathering information, you are generating beliefs about the nature of the world. Those beliefs have status within your brain, which are represented by the very tissues that are ultimately constrained. That layering of the brain cells and the mind -- and the mental life is the toughest question in science to figure out how that works, but that there's this layering, and there -- and interacting in a way I think is the exciting problem to solve in the next hundred years.

REHMNow, to do that do you go back to the brain of an infant for example...

GAZZANIGAMm-hmm.

REHM...to learn how that brain takes in information, reacts to that information, whether it's the sight of the mother, or the sight of a mural on the wall, or a mobile. How does that brain take in and absorb that information and grow from it?

GAZZANIGARight. So the first thing that happened in the last 60 years is that people -- 60 years ago mind you, thought that the brain was a big piece of putty, nothing was written on it, and it was only developed through contingencies of interacting with the environment. So reward and punishment action -- being punished action, being rewarded, and slowly through that process everything was built up, relationships were discovered, concepts came out of this experience, et cetera, et cetera.

GAZZANIGAAnd only in the last 60 years has that been shown to be just the wrong way to look at it. And now there's a group of -- so first of all, two different levels. First of all, the brain guys abandoned that idea, and part was due to my mentor, Roger Sperry, who showed that neurons grow in particular ways to get to particular parts of the brain. In other words, the brain comes structured. It comes with a structure, and then the question becomes, well, what's in that structure?

GAZZANIGAWhat are some of the stuff that's in it from the factory as it were, right? And very clever developmental psychologists are nailing that down and showing all the stuff that comes with this structured brain that grows. And to give you just a quick example, the developmental psychologists are so clever that they drive me crazy because they do their science with such cheap instruments like little baby toys hitting each other in front of another baby, you know, oh, they're outrageously clever people.

GAZZANIGABut anyway, so you have a baby sitting there and you then have two little puppets and one takes a cookie from the other, right? Just A takes a cookie from B. And then a few seconds later, B takes the cookie back, right? Now, there's -- now, does the baby notice this? The baby is totally bored by that because it's just natural that if A steals from B, B's gonna steal back. So reciprocity, retribution, it's all right there at the beginning.

GAZZANIGAAnd if you then do another little trick, my favorite is -- and these are the studies of Renee Baillargeon at the University of Illinois and David Premack. If you do another where A goes over and helps B -- or hinders B, let me -- it's easier to describe it. A goes over and gets in B's way, and B actually was sitting here with C. B had a buddy, C. Now, so A goes and hinders B and then goes back home. The next act is C comes over and actually helps A, right?

REHMHuh. Huh.

GAZZANIGAWell, the baby is shocked at this, because the groups have already formed and A is, you know, has got nothing -- should have nothing to do with B or C because they're in this out group here. So anyway, this is all going on at 13 months. The babies have this all sorted out. So, you realize that with these primitives -- and these are social decisions making, and with these primitives and with all the mental primitives that have been shown using these very simple tricks, we come with a lot of stuff, complex -- complexities built in.

GAZZANIGAIt's already there, and then we build on it through our lives experience and expand on it to -- in the ways that we do, of course.

REHMMichael Gazzaniga, he's author of the new book titled "Who's in Charge: Free Will and the Science of the Brain." He's director of the Sage Center for the Study of the Human Mind at the University of California, Santa Barbara. I'm interested that a lot of your work began with the separation of left hemisphere, right hemisphere. How did that happen?

GAZZANIGAWell, again, going back 50, 60 years ago, there were not too many ways to help patients who suffered epilepsy, and the idea behind that surgery was if you isolated the seizure to one hemisphere, and you do that by disconnecting the two halves of the brain, and the idea is that if the seizures started in one hemisphere it wouldn't spread to the other side and the patient could maintain consciousness and kind of live through the seizure.

REHMAnd I want you to tell us the rest of the story, but first, we have to take a short break. I know about the fascinating stuff that happened between those two hemispheres once separated, but we'll be back after a short break.

REHMAnd we're back with Dr. Michael Gazzaniga. He's the author of a brand new book titled "Who's in Charge: Free Will and the Science of the Brain." Here's a Tweet from Jack that goes right to the heart of your book. He says, "What part of the brain is involved in free will and how do we make certain decisions?" Well, that goes back to what you were talking about before the break, that is the separation of the two hemispheres of the brain. Why don't you complete those thoughts?

GAZZANIGASure. Well, so these patients had their brains divided to control their epilepsy. And then it was our task to figure out of if there were differences between the two hemispheres. Did the left hemisphere specialize in different kind of functions and the right so forth. And the left hemisphere turns out, of course, is the left speaking hemisphere. It understands language, gives speech. And the right has specializations and some kinds of visual domain.

GAZZANIGAAnd what goes on in one hemisphere does not -- is not known by the other hemisphere. So pretty quickly the view was supported that there's actually what was called -- are called modules. There are a whole bunch of modules distributed throughout our brain. And the surgery has a way of disconnecting them one from the other.

GAZZANIGABut what you get a feeling for when you work for this for 50 years is that there is this complex brain with a gazillion different decision systems going on all the time, most of them outside of your realm of conscious awareness. And somehow that pours together into a coherent sense of psychological unity. Yeah, we're all sitting here thinking we're unified in some way. What's the trick? How does that happen? How can these things that are working on different time scales all over the brain, how does that pull together?

GAZZANIGAWell, as it turns out there's a special module in the left brain of most of us that we've dubbed the interpreter. And what it does is try to make sense out of all the behaviors, all the mood modulations you and I experience on a moment-by-moment basis.

REHMAnd you can find that in the left hemisphere.

GAZZANIGAYou can find that in the brain. So the reason we think we're free and acting of our own free will is this thing says, well who else is doing this. I must be doing it. And you build up your personal narrative. And this thing is very strongly present in all of us, which is why we find it so hard and difficult to think that all of our actions are really being organized by a rather automatic brain process. That's why a friend of mine likes to say, you know, that's just where we are. And like the world isn't flat, get over it, this is just the way we're built. Get over it.

REHMHere's another email from Grady who says, "If responsibility comes solely out of social interaction how does one explain the responsibility some people feel toward objects like the planet or a tree or toward oneself with regard to personal health and hygiene?"

GAZZANIGAYeah, those are beliefs generated out of knowledge. And those belief systems are very important in determining how you want to act in behavior. But it all works in a way that makes sense. You're gathering information, you're being informed about the world, you gather beliefs about it. And those beliefs make sense to you and you choose to make decisions based on this acquired information through experience.

GAZZANIGAWhy, in that, would you want any greater freedom than the machine gives you? And some people say, you can have all the freedom you want but actually if I go to all that work I want my machine to work. I don't want some spurious event coming in there and derailing the hard thought that went in to why I shouldn't throw plastic Coke bottles into the ocean, why I shouldn't use big cars. Why should -- you know, I have that belief, I've learned it. It's a belief in my system. I want my machine to work so that it carries out decisions based on that information.

REHMBut suppose nobody else believed that and you were the first environmentalist. What would your social interaction tell you?

GAZZANIGAWell, you would -- as very -- as all of us who come up with an idea prior to its time know, you keep hammering away at it until you try to persuade people into the wisdom of the ways. I don't think that there's any great mystery there in how that works.

REHMTell me about your own beginnings as a neuroscientist.

GAZZANIGAYou know, I'm not comfortable trying to figure out my origins because I can't -- you can't predict forward and my guess is it's -- we're all bad historians. But I do remember ever since I began to think in any serious way of always kind of wanting to know more about, you know, what's this all about kind of thing. What are we doing here? What is this? How do we think? What is...

REHMDid you ask your parents?

GAZZANIGAMy father was a rectal colon surgeon. He wanted me to go to medical school as he said to me one day, Mike, why be a PhD when you can hire one? So he had a very medical bent to him. And -- but then I decided to go to graduate school and he supported me 100 percent so...

REHMAnd you knew you wanted to focus on the workings of the brain?

GAZZANIGAI actually started out wanting to understand more deeply how the nervous system developed or how these neurons got to their specific points. It's a fascinating problem and is one today that still captures so much of neuroscience. But when I went to the lab that was doing it -- Roger Sperry's lab at Cal Tech, they were starting on the split brain story. And they had worked it out in animal models. And it just happened that I was there. I had the first opportunity to study a human. And so I never looked back. That was just a wonderful moment.

REHMAnd still wondrous in the sense of what you continue to learn and discover?

GAZZANIGAOh, oh, you know, the biggest, dirtiest secret in the world is the life and science as the greatest life there is. Because there are points in it where you make a discovery and you know something about nature that no one else knows for a few months, years, moments, whatever it is. And you're just -- you're awed by the fact that some rational approach cracked open a problem and there's new knowledge about it. And that's the foundational sense that I think young scientists and old scientists get. There's nothing like doing an experiment and showing a relationship.

REHMWhy do you think it is that so few young people are going into math and science?

GAZZANIGAI don't know. I don't know if it's because there's -- in math you have to sit down and work. And it needs to be well taught. And whether the teaching of math is as flashy as the teaching of biology where you dissect your first frog, there's something you can do. And math is an abstraction and whether that has a difficulty. But as a great friend of mine once said, you know, once you get rid of math phobia and realize, you know, all those things on one side of the equation equal all the things on the other side of the equation you kind of demystify it a little bit and you can go to work at learning it.

GAZZANIGAIt's a puzzle. A lot of people are trying to solve that problem because it's just -- it's a barrier to entry. And people realize, you know, that's not such a big deal, I think there would be more people involved in scientific interfaces.

REHMSo going back to this question of the infant and the nature nurture argument, what is science saying today about that brain and how it develops?

GAZZANIGASo the most current formulation is that there's an interaction between the developing brain and the environment in which the brain is developing. So that there's -- the simple fact that if you had a -- just to make the simplest model that if you take monozygotic twins and one turns out to be schizophrenic and the other one doesn't, about a 40, 50 percent concordance rate, well what's that? So there obviously were other influences during the development that tilted the outcome in a different way.

GAZZANIGAAnd so the -- there's a huge affect of the environment in tilting the genetic trajectory that is given us and -- is given each of us and understanding those epigenetic interactions, as they're called, and the genetic imperative is what a lot of research is about, trying to figure that out.

REHMAnd trying to understand whether you can somehow influence one brain to go in one way and another brain to go in yet another.

GAZZANIGAYes. That is the perfect mom view of the world. Am I doing something here that is going to make Billy a young Chopin or not? And that's a tougher one. To shape it in a particular way using particular techniques there are lots of ideas about that but which ones will ultimately pay off I think is -- I don't think we have a fine understanding of that.

REHMHere is a question from Joan in Dayton, Ohio. She asks, "Could you please talk about ADD in adults and what part of the brain is affected?"

GAZZANIGAYeah, so ADD is a serious issue that is affected in adults and it is -- there are medications for it. And there are brain systems that are involved in it. And it is a rich act of literature with the latest details of which circuits are involved and are affected by which best medication. I don't have it at my fingertips right now but it is a something to know and you can find out about it in best practices in good medical centers.

REHMBut you're saying if you had a diagram of an adult brain you could pinpoint precisely where that ADD is within the brain?

GAZZANIGAYou could point to circuits that are being modulated in certain ways that seem to be involved. I mean, so that's kind of a soft answer. There's not, oh, you go over here and this thing and if we just put -- if we could put 20 more cells in there everything would be fine. That's not the kind of answer you're gonna get. It's a circuitry that's involved that is not being properly modulated by the -- lots of forces. And somehow these drugs help modulate it better so people's performance change. And that circuit is complex. It's not a -- a one place that has many, many aspects to it.

REHMMichael Gazzaniga. His new book is titled "Who's in Charge: Free Will and the Science of the Brain." And you're listening to "The Diane Rehm Show." I've always thought of the brain, at least in my adult life, as cells and electrical circuits that communicate with each other, impulses that drive these circuits. Explain what you see in looking at a human brain while it's thinking.

GAZZANIGAThe -- if you look at a -- you can, we can do this. You can image a brain at rest. And presumably at rest there are -- well, there are a gazillion cells going on and responding at different level. And a lot of the coherency in that brain at rest, which you're tapping into and measuring, can be recognized as specific circuits. And those specific circuits are something called a default mode network. And it's basically what you're -- what is active when you're daydreaming.

GAZZANIGANow you get up to the question, well, now what parts of the brain are active when I'm thinking about my phone number? We're not there yet. If I show you a pattern of activity that looks like this, can you say I'm thinking about that? No, we can't do that yet. So it's...

REHMBut if I'm listening to music can you -- is a certain part of the brain stimulated?

GAZZANIGASure, sure, sure it is. And they're well worked out circuits there. There's a predominance of activity in the right hemisphere of the brain. If you're a super musician it switches over to the left because the theory is that because when you hear something in B flat, instead of just enjoying it in B flat you call it B flat. And calling it B flat in your mind activates the language center which then flips over your processing to the dominant hemisphere. This was discovered many years ago.

GAZZANIGASo if you're looking at certain visual aspects of the world there's going to be different parts of your brain that are decoding the information coming in that we know exists. But when -- so when you're in the perceptual sphere, auditory, vision, touch you can get pretty good at identifying which parts of the brain are processing the information. It's when you get into things like the nature of thought and the place of where you are having beliefs about the other person -- there're actually advances on those topics but it's far more difficult and they're far more network-based. They're not just a place in the brain like there seems to be a place for certain kinds of visual processes.

REHMOkay. Let's get back to the notion of free will. Say I'm a teenager and I’m buying myself and I'm in a drugstore and I see something I want and think I need but I don't have the money to pay for it. Am I more likely to exercise my free will to steal that if I am alone than I am if others are around me saying, don't do that?

GAZZANIGAWell, there are -- there's social facilitation phenomenon all the time and it depends. If you go in with your gang of friends and they're kind of putting a dare out there, it could be just the opposite that you're more likely to steal it with your friends there than alone because...

REHMBut what's your brain doing?

GAZZANIGAWell, it's computing. It's computing all of these things and -- knowledge from past experience and the potential violation that's going to occur to you personally 'cause you're going to be breaking a rule which you fully understand. So the consequences are there. They're clear and you override them all the time for whatever reasons. I mean, this brain is making decisions on a moment-by-moment basis being influenced by all these factors, one scenario which you just set up.

REHMMichael Gazzaniga. The book is "Who's in Charge: Free Will and the Science of the Brain." Short break and when we come back we'll open the phones.

REHMAnd my guest, Michael Gazzaniga has written a new book, all about the science of the brain and free will. It's titled "Who's In Charge." We're going to open the phone now, 800-433-8850. First to Raleigh, N.C. Good morning, Stephanie.

STEPHANIEHi, Diane. I had a question. My granddaughter was born with multiple brain malformations and the doctors didn't think she would live, but she's two years old and she's actually very engaging and social. And I was wondering if they could tell, perhaps, more with using research with children who have special needs about the social impact and responsibilities and normal brains?

MR. MICHAEL GAZZANIGAWell, that's a superb question and the answer is, we learn from everything. So it's a question of finding the right medical center that might be looking for that kind of problem. But children born with different brains do amazing things and they -- when they adapt to their injury. For example, we were talking earlier about the split brain patients where you in and surgically cut, as adults, the connection between the hemispheres. Well, there's also children born without that structure.

MR. MICHAEL GAZZANIGASo the question is, are they like the adult where you get these dramatic breakdowns of information from the left brain or the right brain? The answer is, if you're born without the thing it seems to have virtually no effect. That the brain has figured out other pathways to get the information communicated because the injury came earlier on and that was adaptations to that different (word?) .

MR. MICHAEL GAZZANIGASo there would be definite -- I guess, the first question would be to examine the, sort of, social level and skills that your child has and then ask the question, well, okay, they're actually normal on these scales or maybe a little impaired on these scales. But then go after, well, how did the brain adapt to allow that to happen? So you one -- could see a whole research program.

REHMIs every human being's brain pretty much the same?

GAZZANIGANo. No, we're all -- gloriously have differences. There's a general plan that's the same. There's parts of the brain are organized in a -- under a general scheme of the back parts vision, the front parts frontal lobes in thinking and motor control and so forth and so on. The large layout is identical, but the individual wires are completely changed. And people think, very confidently, that ultimately the differences between you and your personality and me and my personality will be discovered in those -- knowledge of those minute connections.

GAZZANIGAThere's a book coming out called "The Connectome" and it's very argument is that it's in the fine wiring differences that ultimately we'll understand the differences between people, the individual variation that we see all over the place.

REHMSo do you believe that those differences would be apparent at birth or would they only become apparent in terms of behavior...

GAZZANIGARight.

REHM...within the social norm?

GAZZANIGAYeah. Again, it's not a full story at birth or a full story from the environment. It's a mix. There are going to be some things that are just absolutely built in there. And there's some things that it can be modified through experience. And the ultimate combination of those will make up your connectome and therefore the representations of you will be in that picture which combines both the hard wired and the things that have been modified through experience.

REHMI've never heard that word, connectome...

GAZZANIGAIt's...

REHM...before.

GAZZANIGA...it's coming.

REHMIt's coming.

GAZZANIGAIt's coming, there's a -- the NIH is just a awarded a huge grant to a consortium of people studying the human connectome. And there's...

REHMGive me a definition of connectome.

GAZZANIGAWell, it's like the connection map of all the neurons that are involved in an organism producing behavior. And so people look at the connectomes of flies, of crickets, of -- you name it, sea slugs and now the challenge is, well, let's figure out the connectome to the human. I mean, it's a vast, vast undertaking. But people definitely believe in it as a way of to understand human variation.

REHMSo help me to understand your conclusion about free will.

GAZZANIGASo my point is that, again, that we are learning that we have a very -- we're going to have a very mechanistic understanding of how you and I work. And that fact should not make us feel that we are not responsible for our actions. And the reason is, because that problem has been kicked up to the social level in us, in our social groupings. We have made rules that we want to apply to the social groups within which we live.

GAZZANIGAAnd those rules can be followed. And the question then is -- so this is rather hard lie, you are responsible for your actions. Should you violate one of our social rules, should you carry out a bad deed, should you do an anti-social act, it's another thing to say, okay, what are we going to do about that? But we shouldn't get all confused on the fact that the responsibility was yours and you violated the rule of that culture.

REHMSo what about the use of brain scans in court rooms, for example?

GAZZANIGARight. So this is a -- this is something that -- the scans in the courts aren't ready for this yet. They will be -- it will occur in 10 years, 15 years. The -- and that's because there will be greater specificity to the brain scans. They'll be able to be more accurate in defining a particular persons brain and having it be of consequence to the -- whatever the case is at hand. But right now there are too many outs, there's too many confusions between the problem of taking group data, group averages and applying that problem to this particular defendant.

GAZZANIGAWe're not good at that yet. So that's why any adversarial process, two lawyers will quickly come to determine that this scan is of marginal use. Now, there are lawyers today, distinguished lawyers who say "Let it in the courtroom, now, sure." It's not perfect, but nothing's perfect in the courtroom. Eyewitness testimony is almost worthless.

GAZZANIGAAnd it's the gold standard of our whole judicial system. Let the jury figure out if the preponderance of evidence makes them think one way or the other. So there's arguments within the legal committee about it, but the -- by and large, the neuro-scientific and I think many leading judicial thinkers say it's just too early to have it in the courtroom.

REHMAnd yet people are...

GAZZANIGAYes, right...

REHM...having it in the courtroom.

GAZZANIGA...limited -- it's limited. It's a...

REHMAnd of what value does it serve, even in its limited capacity?

GAZZANIGAWell, this is the problem. I'm not sure it serves a big function right now. The prosecutors point out that, if you allow a scan in a courtroom which has a highly influential role in the case -- if you allow a picture of, say, somebody with left frontal lobe damage and they've gone off and done something terrible and say, see, they have left frontal lobe damage, therefore they have diminished responsibility therefore we can get them off. Prosecutors say, well, we can use that.

GAZZANIGAYou know, or some guy in the public can say, well, we can use that information and I can go around scot-free and hurt people because I got this left frontal lobe lesion because they got this built in excuse. And that can happen because, in fact, people with left frontal lobe lesions, the vast majority of them, don't do bad things.

REHMInteresting. To Ivan in Dallas, Texas. Good morning, you're on the air.

IVANGood morning, thanks for the show. I have three quick points. It sounds Dr. Gazzaniga, like, what your research is including is that cognitive behavioral therapy is valid. Would you say that's true?

GAZZANIGAI think there's a lot to it, yeah.

IVANIt sounds like, you know, if we can change the way we think and can change behavior, the second point real quickly, if you have a lesion and it prevents impulse control, isn't that a reason to consider in someone's guilt in a courtroom?

GAZZANIGAWell, this is a going to come back to the point where that lesion that you say it contributing to some one's impulse control. Frequently there will be a whole constellation of people with that same lesion and they don't have impulse control. So people will argue that you've really zeroed in on the really crucial explanatory system for why this person did something. Now, having said that, that's jurisdictional, too. There are, for instance, civil law systems in Italy, for example, would be very taken with that kind of data and in mitigation, it would play a big role. In our country, it would be argued about and it may or may not, depending on each individual case.

REHMAnd your third point, Ivan?

IVANJust quickly, how does your research connect with the latest thinking or the recent thinking on brain plasticity? Thanks.

GAZZANIGAWell, you know, we're all counting on brain plasticity. So...

REHMExplain brain plasticity.

GAZZANIGAWell, brain plasticity is a term used to cover the notion of learning. In other words, when you learn something, there must be something that changed in your brain because you've now stored the information. And this has been a central problem for neuro-science forever. And we're making headway on it.

REHMWhat headway are you making on serious brain disorders like Alzheimer's?

GAZZANIGAThe hope is that there will be, at the molecular pharmacologic level, interventions that can occur -- that will occur, that helps the impaired neural networks involved to function again.

REHMBut that's the after-the-fact.

GAZZANIGAYeah.

REHMWhat do we know...

GAZZANIGATo ward it off.

REHM...about what brings it on?

GAZZANIGAYeah. Well, there -- you know, there's the quick phrase, use it or lose it, that if you don't maintain and active mental life, you're going to -- these things are going to slip away and without use they will -- your mental life will deteriorate at a rapid rate.

REHMCan you see that mental life deteriorating in...

GAZZANIGAYeah.

REHM...images of the brain?

GAZZANIGAOh, you can certainly track the unwiring of the brain as a...

REHMYou can?

GAZZANIGAOh, yeah. Oh, yeah. Yeah, so you can just -- it's a wonderful story actually that you see the wiring of the brain develop through age, teenage years and into the early 20s. And then we go along, we're paring along and then you start seeing the unwiring of the brain.

REHMWhat's it look like?

GAZZANIGAYou see neurons that are detected by a certain imaging technique called Diffusion Tensor Imaging. And what happens is, you can just see these neurons retreat in their normal projection pattern.

REHMOnce they begin to retreat...

GAZZANIGAYeah.

REHM...is there any way to reenergize them?

GAZZANIGAI think what happens - I don't know the answer to that. I don’t know that it is known. I think what happens at a -- with a little inside into the behavior is that what we do is externalize and begin to use other devices to maintain our mental continuity, the notes taking, the ways of using imagery to remember what we're doing and so forth. So I think we adapt quickly or try to adapt quickly to maintain the flow and the memories that anybody over the age of 45 can begin to detect, they're losing their word finding difficulties.

GAZZANIGAThere's paraphasia where you dance around the thing because you can't remember the damn word. And so as you get into that, I mean, a common experience as those call upon us to lecture in science is that we go to Power Point, right? Well, you get to a talk and they say, oh, well, we don't have a Power Point projector here.

REHMYou're in trouble.

GAZZANIGAYou're in deep trouble.

REHMYeah.

GAZZANIGABecause you have let that be part of your memory system.

REHMDr. Michael Gazzaniga, his new book is title "Who's In Charge." Let's go to Ann Arbor, Mi. Good morning, Kent.

KENTGood morning. So he'd answered my question a little bit after I called in, but I was wondering, so I'm a physicist and a computer scientist and I look at the brain as, you know, this collection of particles and circuits and things. And, you know, as he had mentioned, the brain is being increasingly viewed as being sort of mechanistic. The brain also has a very high noise to signal ratio compared to a lot of computers that we use nowadays. And so in one situation I might make a decision one way and in exactly the same situation I might make it another way, just depending on if a single neuron fires one way or the other which can be pure random chance.

KENTAnd so, I was wondering, that if the brain is basically, you know, a computer and all actions are kind of deterministic like this or all processes in the brain are deterministic, I was wondering if you could, then, sort of define for me what he means with the concept of free will and responsibility if there's no -- if there's not necessarily any agency involved behind this choice making, in terms of just the pure particles interacting?

GAZZANIGARight. Well, thanks for the question because I'd like to clarify that. I'm taking the position that the brain is going to be, someday, completely understood in a mechanistic way. And that therefore this concept of free will is -- should be abandoned. It's just simply isn't relevant to the discussion.

GAZZANIGABut I do not give up the concept of responsibility because I think what we've humans have done is kick that up to the social level and we're accountable to the social group within which we live. And so it's -- we can go ahead and continue on our ways in determining the nature of the brain and that it is not going to put us in a downward spiral about this essential human value which we love, which is to be responsible to our social group.

REHMBut you know if we all know the rules, how come we don't all follow them?

GAZZANIGAWell, there's a million explanations, I suppose, for why we eat the chocolate cake and -- even though we know we shouldn't and things change and you're overwhelmed by a particular reward at a moment and all that stuff. But we don't, as a rule, wax and wane on shooting somebody or not.

REHMI really want to talk to you again in 10 years when you've learned even more. Michael Gazzaniga, his new book "Who's In Charge: Free Will and the Science of the Brain." Thanks for listening all, I'm Diane Rehm.

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