Respuesta defensiva es algo distinto a la experiencia subjetiva de miedo. Transcript: Speaker 1 The first organisms that ever lived had to be able to detect and respond to danger in order to get through the day. And it’s not only detecting and responding to danger, bacteria cells have to do several things that are very common to us. One is they detect and respond to danger. They have to incorporate nutrients and balance fluids and ions, thermo-regulate and reproduce for their species to survive. Now, those things are things that you would think of in terms of animal behavior, but they’re also very characteristic of single-cell microbes. So the question is then, does our behavior, when we do those things, have anything to do with all of that stuff that happened way back there four billion years ago? And I think it does. I mean, obviously we do things very differently than bacteria, but the task of staying alive for us and ourselves, I mean, basically we’re just a bunch of cells, that task is not that Different from what other organisms that exist that are very different from us have to do to get through the day. The point is that these things in an organism are not there to make when we eat or drink or have sex or run away from danger, we have certain subjective experiences. But those subjective experiences are not essential to those behaviors. Those behaviors exist four billion years ago, and the point of them is not to give you feelings, but to keep you alive. (Time 0:07:09)
cerebro comportamiento emociones evolución experiencia
cerebro comportamiento emociones evolución experiencia
The Complicated Question of Consciousness and Attribution of Mental States to Other Organisms Transcript: Speaker 1 You know, obviously it’s a complicated question, and I don’t think we have any hard answers to how consciousness works, although there are lots of, I think, really exciting theories Around these days. But the question is, we see behavior in other organisms, other people, and we attribute states underlying those behaviors to those organisms and people. Now in the case of other people, we’re on pretty safe ground when we see someone doing something, having some sense of what’s going on in their minds when they do it because they have brains That are more or less like ours. Every human has a human brain, every dog has a dog brain, every rat has a rat brain, every bee has a bee brain. But those brains are very different, and so it would make sense that it’s not necessarily exactly the same thing that’s going on in all of those organisms when they have a common behavior. For example, when detecting and responding to danger, a bee, if it has an experience, is probably not having an experience quite like what we have. So the issue then is where do our experiences come from? And can we rely on our ability to observe behavior, to tell us about what’s going on inside another person or another animal’s brain? I think it’s a very complicated situation. So let’s just take humans, for example. When we detect and respond to danger, we almost always feel fear. And so we assume that fear has something to do with the reason that we are responding the way we do when we’re in danger. These things are so entwined in the brain that they seem inextricable, that fear is the reason that we run from the bears. William James said, that may not be right though. (Time 0:09:52)
Hemispheric Brain Functions and Reading Transcript: Speaker 1 So when you put a stimulus into the left hemisphere by presenting it to the right visual feel, the left hemisphere can talk about it because in most people languages on the left side of The brain. So you put a picture of an apple in the right visual field and the left hemisphere says, oh that’s an apple. If you put the same picture into the left visual feel and going to the right hemisphere, you say what did you see? The patient says nothing. That’s his left hemisphere talking. The left hemisphere didn’t see anything. But the right hemisphere did see something because the left hand connected to the right hemisphere can reach in a bag and palpate the optics there and pull out an apple as opposed to whatever Else is in the bag. So the right hemisphere is able to detect that stimulus. Now we had a patient who had an unusual situation because of early brain damage due to the epilepsy. This patient developed the ability to read in his right hemisphere, which was relatively unusual. So we could put words into the right hemisphere and have him do things like we’d flash to the left visual feel, stand up. So he would stand up and say, why did you do that? When you do that kind of situation, you’re talking to the left hemisphere. He said, oh I had to stretch. Or the word was laugh and he kind of chuckled. Ha ha ha. So why did you do that? (Time 0:13:13)
Why the Amygdala is Not the Fear Center of the Brain Transcript: Speaker 1 In this new book, I tried to be very explicit about why we should not be talking about the amygdala as a fear center. Fear is a subjective state word like love and other kinds of words like this. They refer to the experiences that humans have in social and other kinds of situations. I think it’s a problem when we use subjective state terms to describe behavior, to words to describe non-subjective control systems in the brain. The amygdala is a good example of what the problem is. When you lesion the amygdala on a rat, the rat no longer detects and responds to danger. A tone that’s been paired with shock will no longer elicit freezing. The assumption is that the rat is no longer feeling afraid and therefore that’s why it’s not responding. There have been human cases with amygdala damage that still report the experience of fear. This is important because it suggests then that the amygdala is not responsible for the feeling of fear but instead for the behavioral and physiological responses. These things are so entwined in our brains every time we’re freezing to danger, we’re usually afraid. It seems like they go hand in hand. In fact, there are lots of examples besides simply the one or two patients that still feel fear despite having a hole in their amygdala from various kinds of pathology. There are other examples. We can present a stimulus to an intact brain. A person doesn’t have any known pathology in their brain. Present that stimulus in such a way that the person doesn’t know the stimulus is there. This is called subliminal stimulation subliminal perception. (Time 0:21:23)
Activation of the brain in response to masked and unmasked stimuli Transcript: Speaker 1 The person doesn’t know the stimulus is there and doesn’t report feeling fear. If you have the person in an imaging experiment, let’s say an FMRI study, and you record what’s going on in the brain when the person is able to report what the stimulus is or is unable to Report because it’s been masked, what you see is something very interesting. When the stimulus is the threat and it’s masked, you get activation of the visual cortex of the amygdala, and that’s it. When the stimulus is not masked, you get activation of the visual cortex, the amygdala, and the prefrontal cortex as well. The prefrontal cortex is emerging as an important area for the consolidation of our conscious experiences into what they are. (Time 0:24:05)
amígdala corteza prefrontal miedo
The prefrontal cortex and amygdala’s role in fear and conscious experiences Transcript: Speaker 1 The prefrontal cortex is emerging as an important area for the consolidation of our conscious experiences into what they are. When the stimulus makes it to the prefrontal cortex, we can tell other people about our experiences, but when it’s not making it to the prefrontal cortex, those experiences are not Even available to us in our own minds. This is another reason to say that the amygdala is important for the control of responses, but not for the experience of fear. Other reasons, if you look at, for example, people who have problems with fear and anxiety and look at their behavioral responses versus their physiological responses versus their Subjective awareness of events. These three things do not correlate. The behavior and physiology go together pretty well, but the subjective experiences don’t correlate so well with those other physiological and behavioral responses. There are many other examples I could give, but all of this adds up to the fact that the brain mechanisms that control our ability to detect and respond to danger are not the same as those That give rise to our conscious subjective experiences. (Time 0:24:48)
The Evolution of Fear and Emotion in Humans • The ability to detect and respond to danger is inherent in all forms of life. • The limbic system theory proposes conscious emotions arise from evolved circuits. • The speaker proposes cognition came first, not emotion, in the evolution of consciousness. Transcript: Speaker 1 We can follow that all the way up from bacteria to protozoa, from protozoa to sponge and jelly fish on into bilateral organisms, bugs and slugs and all of those things, on into vertebrates, On into fish, reptiles, birds, mammals, us. The ability to detect and respond to danger is as whole as life, but fear may be a much more recent addition. Now, in the deep history of ourselves, there are two, you might say, crazy or radical ideas that come out, and one of them is contrary to popular ideas, such as the limbic system theory That proposes that with the evolution of mammals, certain circuits, the so-called limbic circuits evolved to allow mammals to have these conscious emotions. In later mammals, especially primates and then finally humans, consciousness emerges. In the cognitive sense, we have this cognitive brain on top layered over this limbic brain underneath. Limbic brain is generating our emotions. The cognitive brain is doing language and consciousness and all that, but emotions are conscious in this limbic system theory. Now, what I propose is sort of the opposite, that what came first was cognition, not emotion. And the reason for that is if there are aspects of cognition, if by cognition (Time 0:26:19)
The Evolution of Brain Theory: From Edinger to Modern Times Transcript: Speaker 1 I’ve been on an anti-limbic system kick since the late 80s. I started writing about that. What got me on that was research that I did part time when I was in graduate school. I worked with a guy named Harvey Carton who taught me how to do this new axonal transport pathway tracing stuff in the brain. And he was an evolutionary neurobiologist. So his work was on how brains like bird brains and reptile brains came into being. And one of the things he showed was that in the bird brain and then others have shown in reptiles as well, there are traces of what we call now neocortex. So the limbic system theory was based on a model by a turn of the 20th century German neuroanatomist called Edinger, Ludwig Edinger. Now Edinger had this building block theory of brain evolution where the first you have this basic reptilian brain upon which was stacked a mammalian brain upon which was stacked a newer Mammalian brain. So these three levels were adopted by Paul McLean in the limbic system theory. But in the meantime, and by the meantime, it means since the limbic system theory came along. So like in the 1970s, research began to show that certain aspects of Edinger’s theory were not valid. And in particular, it was this idea that birds and reptiles had no neocortex, which was supposed to be the new part of the mammalian brain. Now if birds and reptiles have elements of neocortex, that kind of challenges the whole limbic system concept because the limbic system was supposed to be the home of emotions and not Cognition. (Time 0:43:04)
Birds and reptiles with elements of neocortex challenge the limbic system concept Transcript: Speaker 1 Now if birds and reptiles have elements of neocortex, that kind of challenges the whole limbic system concept because the limbic system was supposed to be the home of emotions and not Cognition. Whereas the neocortex was the home of cognition. But if those things are not so separated as we go back in evolution, in other words, even reptiles, the ancestors of both birds and mammals, have some primitive neocortex, then the neocortex Did not start with mammals. So pieces of information like that have called the Edinger and thus the limbic system theory into question. And that’s just one of a number of points that could be made. But in general, another thing that we could say is that in terms of the limbic system, the idea that it’s been hard to identify exactly what the limbic system is. The original criteria was connectivity with the hypothalamus, but now with modern techniques, we know the hypothalamus is connected with every part of the brain, including the spinal Cord all the way to the neocortex. So it kind of waters down what the limbic system might be. At the same time, the idea that emotions are part of the limbic system, whereas cognition and thoughts are part of the neocortex is no longer valid because we find that there are certain Aspects of emotion that the neocortex is particularly required for. (Time 0:44:46)
The Role of the Limbic System in Emotions and Cognition - A Podcast Discussion Transcript: Speaker 2 Yeah, I kind of now use reference to the limbic system as a quick screen when I get sent a book because I get sent lots of books. And as soon as the author refers to the limbic system, I stop. I know that’s probably not fair. The field is still talking about the limbic system. I know, but if they’re not going to then say something that shows that they’re up to date on its current status, I get worried. Speaker 1 So I talked about one crazy, radical idea that cognition came first before emotion. But the other idea that maybe even a little wilder than the first is that emotions are not initially a product of natural selection. Now that is going to be controversial and may be surprised you or whoever else is listening right now to say something like that. But what I think happened was that emotions are these cognitively assembled experiences. I know you’ve had Lisa Barrett on. And our views are moderately similar on this topic that emotions are conscious experiences that are constructed by these cognitive processes. (Time 0:46:48)