Saturday, May 01, 2010

Getting to Know Joseph LeDoux, Neuroscientist & Author

A while back, I bought a copy of Joseph LeDoux's The Synaptic Self: How Our Brains Become Who we Are, or more precisely, I messed up and bought three copies (long story). The Emotional Brain: The Mysterious Underpinnings of Emotional Life is now on my reading list.

Anyway, I finally got around to reading it, so I decided to see what other info I could find on him.

So there's this segment on NPR's Science Friday:
Science Friday > Archives > 2002 > March > March 29, 2002:
Hour Two: Joseph LeDoux - 'Synaptic Self'

In animals, fear is a behavior that's both innate and learned. A rat will freeze at the sight of its very first cat -- but it can also be taught to freeze when there's no cat in sight. What controls these responses? Is it the same as what controls similar responses in humans? In this hour of Science Friday, Ira talks with scientist Joseph LeDoux about his new book "The Synaptic Self: How Our Brains Become Who We Are."

There's this podcast from The Beautiful Brain - seems LeDoux is also a rocker.
By Noah Hutton
Filed under Podcasts February 5th, 2010 no comments


This month we are proud to present an interview with Joseph LeDoux, the acclaimed neuroscientist and bestselling author of The Emotional Brain and The Synaptic Self. LeDoux’s research into emotion in the brain has led to groundbreaking findings in the realms of fear and memory. His primary area of concern is the amygdala, the center of fear processing in the brain, and most recently his work in animal models has uncovered just how flexible and dynamic memory can be… kind of like Joe himself, who also is the frontman for the rock band The Amygdaloids, whose brain-themed songs will be released in an album featuring Rosanne Cash later this year. Science, rock music, and the news, all on this edition of The Beautiful Brain Podcast. Total runtime: 33:42

Listen to the Full Episode:

Download Podcast MP3 (24 MB)

Download and Subscribe to Podcast on iTunes:

EDGE has a lengthy conversation with LeDoux on emotions, memories, and brain function.

Parallel Memories: Putting Emotions Back Into The Brain

A Talk With Joseph LeDoux

JB: Emotions and the brain? Isn't this something new for scientists?

LEDOUX: Twenty years ago no one cared about emotions and the brain, but it seems in the last couple of years there's been a flurry of activity. One reason for this may be that the topic was ignored for so long, and the vacuum is being filled. Another, though, is that there have been some successes in approaching the problem, and these have changed peoples' minds about the feasibility of studying emotions in the brain.

The most successful efforts have come from the study of fear. Fear is a relatively tractable emotion, unlike love or hope which are difficult to pin down. It's always easier to study brain functions that involve clearly defined stimuli and responses than those that don't. For fear, you can easily create experimental situations where the onset of a simple stimulus that warns of impending danger elicits a set of stereotyped responses in an animal, like a rat, that are very similar to the kinds of responses that occur in a human facing danger. By following the flow of the stimulus through the brain from the stimulus processing pathways to the response control networks, it's possible to identify the basic neural circuits involved. We've done this for fear.

JB: How did you get into this?

LEDOUX: I got interested in emotions while I was studying something completely different. I was doing split-brain research as a graduate student with Mike Gazzaniga. Mike and I were studying how information is transferred between the hemispheres of these patients. One of the questions we asked was what happens when we put information in the right hemisphere. Remember, it's the left hemisphere that usually does the talking, so information in the right hemisphere can't ordinarily be talked about in these patients. We put emotional information in the right hemisphere, and the left hemisphere couldn't tell us what it saw, but it could tell us how it felt about it. That led us to the idea that emotional information and information about the content of what a stimulus is, are processed by different pathways in the brain. That seemed very interesting, and I decided I wanted to pursue it.

At the time, I felt that the only way to go about studies of the pathways of emotional processing was to turn to an animal model, where you can do experimental lesions, cell recordings, pathway tracing and so on. The reason you want to do these kinds of studies is not to satisfy some reductionistic urge, but because they can help you see how emotion is put together in the brain, and this can tell you about how the function itself works. Today, there are more sophisticated ways of studying the human brain, such as functional imaging. These can give you a picture of the brain in some emotional state, but you can't then ask the next question. You want to know how the activated region fits into a larger system. You really can't get to those kinds of questions in humans and have to turn to the animal models for answers. The animal work, in other words, gives the framework for interpreting the snapshots we get from human imaging studies. Without the animal studies, though, many of the human studies probably never have been done, and if they had, they wouldn't be so readily interpretable.

So I left the world of human neuropsychology and went into animal research after finishing my PhD and a short post doc. Mike and I had moved to Cornell Medical School and after a year or so I hooked up with Don Reis in the Neurobiology Lab there. The lab's mission was to study the brain's control over the autonomic nervous system, and basically I was told that I could do whatever I wanted as long as I recorded blood pressure. So I developed a blood pressure model of conditioned fear.

I used conditioned fear because it seemed like a relatively straightforward technique: you give a meaningless tone followed by a mild shock a few times, and pretty soon the tone starts eliciting a blood pressure response. It was a good way to create an emotional reaction to the tone on the spot in an animal that wasn't afraid of the tone and didn't have any emotional reaction to it to begin with. Since the tone gets to the brain by way of the auditory system and the response comes out of the brain through the autonomic nervous system, the trick was to figure out how the auditory system is linked up with the autonomic system. By using a combination of brain lesions, neural recordings, and pathway tracing techniques, we were able to figure this out. The answer, in short, is that the amygdala turned out to be a necessary and sufficient link between the auditory system and the autonomic nervous system. However, in a more general sense, the amygdala is the link between all sensory systems and all fear responses systems. It's the part of the brain involved independent of how the stimulus gets into the brain and how the response comes out.

JB: I find it interesting that the first emotion you studied was fear.

LEDOUX: When I first began this work in the early 1980s, I was using fear conditioning techniques because they were convenient. As I said, you can take the stimulus, pair it with the shock one or two times and, as a result, create an emotional reaction that's relatively profound in the animal. I thought at the time that this was going to be a way of identifying a universal emotional system in the brain, something akin to the limbic system. I no longer feel that way. I think that the study of the limbic system, or more generally the idea that there is an emotion system in the brain, is misguided. I came to this conclusion empirically. Once we had outlined a neural circuit for fear responses, it was obvious that the limbic system had little to do with it. The only so-called limbic area involved was the amygdala. And the hippocampus, the centerpiece of the limbic system, had been implicated in non-emotional processes like memory and spatial behavior. It seemed clear that the limbic system, if it existed at all, was not systematically involved in any clear way. I decided I didn't need the limbic system concept to think about how fear works in the brain. But that still doesn't wholly justify the focus on fear to the exclusion of other emotions.

I've come to think that emotions are products of different systems, each of which evolved to take care of problems of survival, like defending against danger, finding mates and food, and so forth. These systems solve behavioral problems of survival. Detecting and responding to danger requires different kinds of sensory and cognitive processes, and different kinds of motor outputs, different kinds of feedback networks, and so on, than finding a mate or finding food. Because of these unique requirements, I think different systems of the brain are going to be involved in the different kinds of emotions.

A related point is that emotion systems, like the fear system, didn't come about to create feelings (like the feeling of being afraid when in danger). I think feelings came much later in evolution. All animals have to be able to detect and respond to danger, regardless of the kind of cognitive architecture they have. This is as true of bees and worms and snails, as it is of fish, frogs, birds, rats, and people. Fear conditioning, by the way, occurs in all animals. And in all those that have an amygdala, the amygdala appears to be the key. The list at this point includes reptiles, birds, and a host of mammals, including humans. I think it's safe to say fear behavior preceded fear feelings in evolution. If so, feelings are probably the wrong thing to focus on when we study emotions. In this sense, animals were unconscious, unfeeling, and non-linguistic before they were conscious, feeling, and linguistic. It's too bad that we define the more basic processes as the negation processes that typify the human brain. It's possible that once consciousness and feelings came along that new kinds of emotions specifically tied to these evolved. But I'm trying to understand the things about emotions that are similar in humans and other animals so that I can work on emotions through the brain.

I tend to agree with theorists who say there are basic emotions that are hard-wired into the brain's architecture, and that one of the advantages of having an extra big cortex is that we can blend different hard-wired emotions together to create softer emotions, where cognitions come into play in a major way. For example, while detection and responding to danger may be built into the brain, the capacity to be afraid of falling in love is something that requires the cognitive integration of the system for finding mates and the system for defending against predators. While I'm sympathetic towards the basic emotions view, I don't really ascribe to it. It requires that you state what the different emotions are. That just leads to arguments. I'd rather spend my time worrying about one well accepted emotion and its organization in the brain than fighting over whether this or that mental process is an emotion or not.

There is much more - read the rest of the interview.

And speaking of emotions, here is a review of The Emotional Brain by none other than Antonio Damasio, maybe the leading neuroscientist in the field of emotions and the self.

Antonio R. Damasio's review of Joseph LeDoux's book The Emotional Brain.

[From: A.R. Damasio, Thinking and Feeling, Scientific American, June 1997.]


Review by Antonio R. Damasio of THE EMOTIONAL BRAIN: THE MYSTERIOUS UNDERPINNINGS OF EMOTIONAL LIFE, by Joseph LeDoux, Simon & Schuster, New York, 1996 ($25)
"We may never understand exactly why emotion was given the cold shoulder of science for almost 100 years. By the last quarter of the 19th century, Charles Darwin, William James and Sigmund Freud had thought and written brilliantly about the nature of emotion, about the possible biological mechanisms behind it and about the ways in which it could be disturbed. The British neurologist John Hughlings Jackson had even made a first stab at discerning the anatomy of human emotion by planting it in the right cerebral hemisphere. There would have been every reason to expect that the budding brain sciences would concern themselves with emotion in much the same way they had been taking on language or visual perception.

"Curiously, it never came to pass. Emotion was consistently left out of the mainstream of what became neuroscience and cognitive science. A handful of psychologists, such as Stanley Schachter of Columbia University, carried on important studies on emotion; psychiatrists and pharmacologists concerned with mood disorders developed and applied drugs that gave indirect information on the mechanisms of emotion. By and large, however, neuroscience and cognitive science neglected emotion until quite recently. In what may have been the last gasp of post-Cartesian and post-Kantian intellectual dryness, emotion was not trusted, in real life or in the laboratory. Too subjective, it was said, too elusive, let's face it, too irrational for the likes of modern science.

"Some of us have long thought this attitude was wasteful, not to say silly, and proceeded as if a field called "neurobiology of emotion" already existed. That missing field was created in the process, and Joseph LeDoux, author of The Emotional Brain, stands out among the creators. At his laboratory at New York University, LeDoux has made a rich contribution to the understanding of one of the star emotions, fear. Working in animals and concentrating on a pivotal brain region known as the amygdala, LeDoux has performed a number of ingenious experiments that throw light onto some of the neural mechanisms of the fear response. Much of what he has discovered is applicable to other emotions and to human beings. It also provides a valuable blueprint for further animal studies.

"The Emotional Brain draws its strengths heavily from the author's own work. There is no substitute for the firsthand knowledge of how the process of discovery unfolds--sometimes exciting, sometimes painful. LeDoux incorporates his experience to produce an account that is informative (for those who may wish to learn about one approach to systems neuroscience), useful (for specialists) and pleasant (for all). The writing is direct, without subterfuge or pretension, and the author even acknowledges colleagues--a duty so rarely observed in science trade books that it should certainly be regarded as a virtue.

"LeDoux frames his account with a well-articulated reflection on the past and future of emotion research. With remarkable courage, he takes on the long-standing controversy over the role of the body in the processing of emotions. This controversy is probably the central issue in the neurobiology of emotion. William James proposed that when the brain triggered emotions they were enacted in the body and that the changes resulting from such an enactment were subsequently represented in the brain and apprehended consciously. A number of critics countered that the essential components of the mechanism occurred within the brain and that body responses were not essential for the feeling of an emotion. Although its arguments were muddled and uninformed, the anti-James camp was the winner, perhaps because the incompleteness of James's framework (inevitable given the limited knowledge of the time) rendered it vulnerable.

"That this state of affairs prevailed until recently can only be explained by subsequent researchers' reluctance to examine the problem in any depth. LeDoux is not shy in his assessment: "It's hard to believe that after all these years we actually still don't have a clear and definitive understanding of the role of body states in emotions. However, I'm placing my bets in favor of feedback playing a role. Emotional systems evolved as ways of matching bodily responses with the demands being made by the environment, and I can't see many ways that a full-blooded emotional feeling could exist without a body attached to the brain that is trying to have the feeling."

"He also replies eloquently to the oft-asked question of the emotional status of tetraplegics who have lesions in the cervical spinal cord (and who therefore have little feeling or motor control below the level of the neck). The continuing ability of tetraplegics to feel some emotion seems to speak against the role of body feedback in emotion. But few, if any, injuries ever destroy the cord completely and thus some body sensory input still goes through. Moreover, a considerable amount of visceral input bypasses the cord altogether and enters the central nervous system at the brain stem level via cranial nerves. Patients with spinal cord lesions do display some changes in emotional processing, a clear witness to the value of on-line body signaling since even partial damage can have an effect.

"LeDoux's argument is completed by my own proposal for an "as-if-body-loop," as presented in my book Descartes' Error. I have suggested, and LeDoux agrees, that some emotional responses can change somatosensory representations in the brain directly, "as if" the latter were receiving signals from the body, although in effect the body is bypassed. People probably have both body-loop and as-if-body-loop mechanisms to suit diverse processing conditions. The critical point, however, is that both mechanisms are body-related.

"I also enjoyed LeDoux's perspective on the closely related argument that the body would not provide enough variety of signals to signify the different emotions we experience. I have pointed out the weaknesses in this argument, and I am pleased LeDoux endorses the idea that body signals can easily provide the diversity of emotional patterns. He writes, "When all the interactions between the various systems are taken together, the possibilities for the generation of emotion-specific patterns of feedback are staggering. This is especially true when considered from the point of view of what would be necessary to scientifically document the existence of these patterns, or, even more difficult, to prove that feedback is not important."

"I do not wish to disappoint readers bored by so much agreement between reviewer and author, so I will say I do not endorse LeDoux's general attitude toward feelings (though I understand well why he holds it). In essence, LeDoux believes the investigative effort in our field should focus on the biological responses that constitute an emotion because these responses can be identified and manipulated in animal experiments, whereas feelings, which are the perception of the emotional responses, can be studied only with the cooperation of the self that experiences them. His fear of feelings is really twofold. On the one hand, animals may have feelings, but we cannot study them effectively. On the other, the "soft" study of feelings was associated in the past with some of the confusion that arose from poorly conceived studies of emotion.

"I disagree, because times and technologies have changed. The modern techniques of cognitive neuroscience allow us to study emotion in animals and both emotion and feeling in humans. The combination of animal and human studies will eventually reveal, in seamless fashion, the continuity of processes that begin with a triggering mind stimulus, proceed to emotional responses and to their sensory representation, and conclude with the conscious readout known as feelings.

"In the meantime, The Emotional Brain is an excellent introduction to the strange history of the neurobiology of emotion and a preview of what lies ahead."

ANTONIO R. DAMASIO is the author of Descartes' Error: Emotion, Reason and the Human Brain (G.P. Putnam's Sons, 1994). He is Van Allen Professor and head of neurology at the University of Iowa College of Medicine.
Here is a brief lecture from Mind & Reality: A Multidisciplinary Symposium on Consciousness.

No comments: