European Federation of Neurological Societies

Transcription

(Indistinct audio) I'm sure everyone remembers this, when the pilot of that plane took off from LaGuardia airport in New York and within minutes recognised two things: First, that he no longer had engine power and second, he didn't have time to return to LaGuardia, there wasn't enough time to return to the airport, and so he crash landed in the Hudson river. If the pilot of this plane had instead been a computer, everyone would have died. The lives of the 155 people on board were saved because the pilot was a human being and because he had a human brain. Specifically, because he had a properly functioning part of the brain known as the frontal lobe. The brain works through a series of networks; when we have cognitive thought, almost all of it is activated but some areas are more critical than others, a fact I will reiterate often. If there's one part of the human brain that links us to our personality it's the frontal lobe. It's what makes us different from every other person here today... what distinguishes us from other species. If you get a lesion on the rear part of your brain, which is central to the way we perceive the world around us, undoubtedly, you'll lack a full ability to perceive the world, but you'll be the same person. If you damage your frontal lobe, you will never be the same as before, you'll start to be different, have a change in personality. The frontal lobe contains different neurons to other parts of the brain. For example, we have neurons for the olfactory system, our sense of smell. The network that controls this sense of smell contains neurons which essentially respond to olfactory stimuli. We have some that process our vision by responding to visual stimuli. In contrast, as you would expect for the most critical part of the human brain, the frontal lobe responds to many different things according to the given situation. For example, they can be stimulated by a dog or the sight of a cat, depending on the context. This part of the brain, which is critical to us all, is fully matured between the ages of 20 and 30. It plays a key role in various intellectual and cognitive functions, for example those relating to making plans and taking decisions, to memory, language, and social interaction. My brain is constantly changing because I'm here, and your brains are also changing as you listen to me; either you like what I'm saying or you don't. Social interaction changes our brains. Even in an elevator, when we see someone else, we just have to say something to them, we evaluate whether they like us or not... Our brain becomes activated and so does theirs. The human brain cannot be understood as an individual entity; we have to understand it through the interaction between two brains. If you were to put me on the spot and say, 'Facundo, how would you sum up the human brain?' I would say, 'Well, it's a social organ'. And part of the human brain's complexity, many researchers agree, can be explained by the social complexity that our species has attained. And if you don't believe in our social complexity, just look at everything we've created: the chairs, the microphone, the broken computer, my shirt, and everything that we produce today. We've learnt a lot about the frontal lobe through patients who, regrettably, developed neurological or psychiatric problems. But we've also learnt a lot through new technology, such as imaging. Today, we're able to study the brain with equipment that can see in real time the things that occur in our brains when we imagine, when we memorise. And human memory is not a unitary system: there are different types of memory. There's memory for where and when: I graduated on such a day at such a place. There's memory known as episodic memory, involving a key part of the hippocampus. There's another memory that I'm using now called 'online' memory: I'm saying words that I wasn't just a few seconds ago, for example. Or when I have a telephone number in my head, I dial it, speak to the person, and then forget the number, that's basically 'online' memory. This type of memory depends a great deal on the frontal lobe. But there are other types of memory which, from lesions and animal studies, we knew were largely independent from the frontal lobe or our semantic memory: knowing that Montevideo is the capital of Uruguay; we don't know when we learnt this, it's become a notion, like knowing what a shirt is. But now, through imaging technology, we know the frontal lobe is activated by all these human memory systems: with an autobiographical, semantic, 'online' or episodic memory, aside from the other parts of the brain we already knew about - in animals and in humans - we now know that, the frontal lobe plays an important role. And speaking of memory, I'd like to tell you that advances in neuroscience over the last few decades are owed to advances in genetics and imaging technology. And that now, more scientists than ever in the history of humanity have demonstrated that human memory is the most advanced there is. When you recall a memory, it becomes changeable and when you go back to storing that memory, it is stored, and if the information you store coincides with the event that took place, you'll remember it in that way. But when you recall a memory, if you start to add things and store the information with different emotional contexts, or with different situations, what you will remember next time won't be what actually happened but rather your last recollection. Basically - I'm repeating this because it's important - when a person recalls a memory, that memory becomes changeable and then, it is stored again like a Word document on a computer. Whatever you store will be what you remember next time. If two people in love go on a trip and one is more in love than the other and talks about it a hundred times, while the other only talks about it twice, undoubtedly, the second person will be more accurate because the one who told the story a hundred times will add emotion to the trip and the context which don't have anything to do with the reality. We have learnt that the frontal lobe is responsible for making plans, managing the temporal role in language, and for emotion and rational thought by testing on patients. One of those tests is the lobotomy. The lobotomy is a procedure which, thankfully, is no longer used, but which was very popular in Europe and the United States several decades ago until it ceased in the 1970s. Essentially, a thin metal instrument was forced up behind the eye socket and into the brain, allowing them to destroy the frontal lobe in patients with incurable depression; who had obsessions preventing them from leading an independent life; or who were in intense pain. And there was a very expressive photo showing a person to be extremely anxious before the surgery and completely liberated with a Cuban cigar after. They had cured his obsessions, but he stopped being the same person: he was completely uninhibited, unconcerned. And sadly, this led us to understand the effects of a frontal lobe lesion. We also learnt about the effects of a frontal lobe lesion following one of nature's experiments which took place in the town of Cavendish, Vermont. In Cavendish, a company was constructing a railway and the foreman, Phineas Gage, was very obsessive. He got to work early, was the last to leave, everybody trusted his word, the company bosses trusted him, the workers that he managed were very happy. He was a very trustworthy person, until the moment when a mine exploded and a rod of metal cut across his frontal lobe. The rod exited his body; it didn't become lodged. The front part of his brain had basically disappeared. He was taken to Boston, and the rod remains at the Harvard Medical School today. It's a very famous case. I'm not breaking any doctor-patient confidentiality; all the info I'm about to give was widespread in the international media, both scientific and not. First, Phineas Gage arrived conscious at the hospital in Boston. Second, he was speaking perfectly, he remembered everything that happened. He was discharged a week later, with a hole in the anterior part of his brain. Medical circles in Boston wondered, 'what does this part do?' Because Phineas Gage left hospital with the same level of intelligence. Science can't fully measure a person's intelligence - humour, irony, bravery can't be measured - but certain aspects of a person's analytical intelligence can be measured. And Gage's analytical intelligence was preserved. His language skills, memory, attention skills and spacial awareness were all preserved, he had no motor deficit. So the doctors in Boston asked, 'What does this part of the brain do?'... and then they realised. Phineas Gage had become completely uninhibited, he started to make financial decisions that were against his own interests, as he did with social, work and family decisions. I don't want to make any moral judgement about what is good or bad with such decisions, but if someone used to make advantageous decisions in life before having an accident, and afterwards started to make decisions that conflicted with their social, work and family interests, clearly there is a decision-making deficit. The interesting thing is that Phineas Gage's deficit couldn't be explained as if he had lost the ability to reason; because his intellect, memory, attention, intelligence, language were all intact. So what had happened? The metal rod had cut across his frontal lobe, which has another function, a function I didn't mention earlier: it controls our emotions and rationality. The frontal lobe is the part of our brain that takes on the role of adapting the innate impulses that we all have to suit society. We all want to throw a punch back at the person who sucker punched us, we all do. But some people don't. We are all drawn to sexual stimulation, all of us. And we all want to tell a person who's annoying, who's cynical or who lies that they are a liar, or a cynic. And that is what people who have damaged their frontal lobe do. So, Phineas Gage's deficit was an emotional one, which guided his 'rational' decision making. And as human beings, we're constantly making decisions. Life doesn't just lead us to make decisions when we choose a career path, when we choose a job, or which dish to eat in a restaurant, or when I consciously chose this shirt, looking to see if I had a similar one or not. Obviously, these decisions are conscious ones, and we make lots of conscious decisions, but we live our lives making decisions. What's your name? Mercedes. Right now, Mercedes is making decisions: whether to look at me, at the screen, or at that man; whether to think about what I'm saying or what she's going to eat later. We live our lives making decisions. And the brain, through evolution, has developed a decision-making mechanism which doesn't always evaluate the pros and cons because we wouldn't have time to make the decisions we do. Because decisions aren't just about choosing a meal, or a shirt, or a career path. Having to make decisions is constant, and through evolution, the human brain has developed an automatic mechanism, which is often subconscious, that looks at the change in circumstances, just like now with this talk: Before this talk I thought I had a frontal deficit, but I'm managing ok. The context changed and I'm able to adapt to it. The same goes for the pilot of the airplane. Human decision making isn't a logical or computational process, rather it's guided by emotion. Patients like Phineas Gage have what is known as 'myopia for the future'. Phineas Gage knew what was right and wrong, he knew that the decisions he took wouldn't allow him to work. Frontal lobe patients know what's right and what's wrong, it's not a problem of knowledge. However, they opt for risk in return for immediate reward. That's why neurobiology often says these patients have myopia for the future. They can't resist immediate temptation, even when that immediate temptation could be detrimental in the long term. And this biological theory for decision making allows us to understand certain aspects in a new light, not all aspects because they're complex phenomena with many factors. But take obesity, for example, there's a tub of ice cream in every supermarket, and some people can't resist eating it despite knowing that they're going to add 500 calories later that afternoon or the next morning, or immediately after eating it. The same goes for severe drug addiction or compulsive gambling. A compulsive gambler doesn't gamble occasionally in a casino, rather he can't live without gambling. There's a case of a patient of mine who spent months saving up for his honeymoon, and the day before the wedding he gambled it. Clearly, he wasn't thinking about the future: that his wife was going to kill him. Now we're going to listen to a bit of music, and I'm gong to tell you how it relates to the frontal lobe. (Music) This is Ravel's Bolero. Unfortunately, Ravel suffered from an illness that affected his frontal lobe. This is well evidenced by medical documents. And many researchers believe in the theory that part of his artistic work was influenced by his frontal illness. Because frontal patients also persist; they are often obsessive. They're unable to exercise the cognitive flexibility necessary to survive. In the whole of the Bolero, the same melody is repeated about 17 times and the scientific papers of some researchers hold the theory that it was affected by the illness. You can see that this persistence, this obsessiveness is good when you're a genius; the issue is when you persist and you're not a genius. It was thought that the frontal lobe is bigger in humans than in other species. Today, we know it's not. Today, we know that part of the frontal lobe's complexity may be due to the brain's connections and not so much the size of the lobe itself. This is a study that we did when I lived in Cambridge, England, so you see, there have been many cases like Phineas Gage in history. We studied a group of 30 patients like Phineas Gage. Neurobiology doesn't establish principles based on a single case; there are many laboratories in the world that have spent decades studying the phenomena that were first presented in Gage. Frontal lobe damage doesn't just result from injury, from an iron rod or a cerebrovascular accident. This is a degenerative illness, like Alzheimer's, but instead of affecting the hippocampus, which controls memory, it affects the degenerative frontal lobe. Here's a photo from the New York Times, showing an American senator for New Mexico who renounced his position due to frontal illness. It's interesting that most don't notice the illness because it doesn't act like Alzheimer's; it affects behaviour rather than memory or sense of direction, and the patients are sometimes more congenial. Here's the photo I wanted to show you about how obesity, compulsive gambling and also drug addiction are being researched as resulting from decision-making deficits; the inability to resist immediate reward despite it being detrimental in the long run. Modern man relies on every possible resource to solve many of the most pressing social problems, such as poverty. However, with social matters comes emotion. When we speak to a boss, there's emotion; when we speak to our partner, there's emotion; when we run into competition, there's emotion; when we approach a person, there's emotion. Social matters involve emotion because they implicitly contain power, submission, and personal gain. The focus on reason, on controlling human behaviour and anticipating behaviour has led to the mistaken concept that we are ruled by reason. Human history is in clear contradiction with the fact that we are completely rational beings. On a final note, I want to say that myopia for the future is not linked solely to neurology. And I'd like to close with a personal story, which I'm sure relates to many of you, and that is the story of Argentinian public school. Like many of you, I'm the product of our country's public school system. This is Arroyo Dulce, a small rural village in between Pergamino and Salto. I went there for primary and secondary school, then to the University of Buenos Aires. After, I left the country before returning to Argentina. Like many of you, this public school system has allowed me to fulfill my dreams and my goals. It wasn't the only thing, but it was an important basis that enabled me to fulfil my personal dreams and goals. And this public education project, which differs from those in other Latin American countries, and of which Argentinians are very proud, was conceived by a generation of Argentinians who clearly didn't have myopia for the future, who were able to imagine a system of education beyond their biological lifetimes. And for that reason I hope and wish, like I'm sure all of you hope and wish, that the next generations of Argentinians, including my sons, four-year-old Pedrito and six-year-old Manuela, who are both in the audience, will say the same about us: that we didn't have myopia for the future. Thank you. (Applause)