JB: Where do you expect your research will take you?
LEDOUX: Right now my work is headed deeper and deeper into cellular-molecular events underlying how emotions are learned and stored. We are trying to understand as much as we can about how these memories are formed at the cellular level which has taken us into studies of synaptic plasticity, how changes happen at the level of individual synapses when this kind of learning takes place. We are asking questions about what neurotransmitters are involved and what sort of molecular changes take place to stabilize these memories over the long run. These studies are just beginning and they will take us well through into the next century. At the same time it's important not to lose sight of the fact that we're dealing with a psychological problem with important behavioral consequences. We need to study the behavior as well as the molecules. We try to work at all these levels; at the level of the behavioral system as well as the cellular and molecular systems.
JB: What has your work made explicit?
LEDOUX: There are ways that the brain can produce emotional responses in us that have very little to do with what we think we're dealing with or talking about or thinking about at the time. In other words, emotional reactions can be elicited independent of our conscious thought processes. For example, we've found pathways that take information into the amygdala without first going through the neocortex, which is where you need to process it in order to figure out exactly what it is and be conscious of it. So, emotions can be and, in fact, probably are mostly processed at an unconscious level. We become conscious and aware of all this after the fact. Conscious feelings of fear are thus not a necessary step in the link between a dangerous stimulus and emotional responses. We're probably not as in control of our emotions as we sometimes think we are, or wish to be.
Emotional reactions that occur in this quick and dirty way are really reactions that are important in survival situations. The advantage is that by allowing evolution to do the thinking for you at first, you basically buy the time that you need to think about the situation and do the most reasonable thing. For example, freezing is often the first thing people and other animals do when sudden danger appears. Predators respond to movement, so freezing is overall probably the best single thing to do first, at least it was for our distant ancestors. If they had to think about what to do first, they'd have been so caught up in the thought process they'd probably fidget around and then get eaten.
The Atlanta Olympic Bombing is a nice illustration of this. The bomb goes off and everyone hunches over in the freezing posture for a couple of seconds, and then they take off running. You can almost see the cognitive gears turning while they're freezing. Although we're not in direct control of these rapid fire unconscious emotional responses, I don't think that they are necessarily going to be things that someone can use as a legal defense, for example, for having carried out a very detailed crime, a murder or a rape or something of that nature. These quick and dirty systems produce relatively simple rapid responses (like freezing) in life-threatening situations. They're more likely to be used by the victim than by the perpetrator.
JB: What about therapy?
LEDOUX: The connectivity of the amygdala with the neo-cortex is not symmetrical. The amygdala projects back to the neo-cortex in a much stronger sense than the neo-cortex projects to the amygdala. David Amaral has made this point from studies of primate brains. The implication is that the ability of the amygdala to control the cortex is greater than the ability of the cortex to control the amygdala. And this may explain why it's so hard for us to will away anxiety; emotions, once they're set into play, are very difficult to turn off. Hormones and other long-acting substances are released in the body during emotions. These return to the brain and tend to lock you into the state you're in at the time. Once you're in that state it's very difficult for the cortex to find a way of working its way down to the amygdala and shutting it off.
This is why therapy is probably such a long and difficult process, because the neocortex is using imperfect channels of communication to try and grab hold of the amygdala and control it. It's like trying to find your way from New York to Boston by way of country roads rather than superhighways. The amygdala can control the neocortex very easily, because all it has to do is arouse lots of areas in a very non specific way. But for the cortex to then turn all of that off is a very difficult job. The evolution of the brain is at a point where we don't have the connectivity that would be necessary for cognitive systems to more efficiently control our emotions. But it's not clear to me that would necessarily be a good thing, because Mr. Spock is not necessarily an ideal kind of human that we'd like to become.
Designer drugs could be really practical, and I'm surprised that the drug companies are not knocking at my door to find out how to make drugs that could do more specific things than the drugs that are available. We know the circuit through which fear is elicited, and we know the specific points in that circuit that are involved. As we begin to identify the neurotransmitters that are involved in the elicitation of fear, it seems that we could probably come up with a chemical profile of fear in the amygdala. A particular drug could be developed that attacks that profile. For example, if you take Valium, it might make you sleepy and reduce your sex drive in addition to making you less anxious because it affects GABA transmission throughout your entire brain. But if you could develop a Valium that only acted in the amygdala, then you would have a drug that works at the particular sites involved in fear. That's pie in the sky at this point, but it's something they should be thinking about.
JB: How is your work being received today?
LEDOUX: I've been amazed that almost all areas of psychology have not only been sympathetic, but are reaching out and trying to find out as much about my work and the work of people like me. It's really surprising that this extends into psychoanalysis as well. I have received a number of invitations to speak to psychoanalytic groups and to attend meetings to try and understand how concepts about the emotional brain could help them understand that psychoanalysis and might take them into the 21st century. Psychoanalysis is in relatively bad shape right now. Young psychiatrists are not going into the field, so the elders are trying to figure out a way to make the field more appealing. I think they see neuroscience as a possible bridge.
JB: Who else?
LEDOUX: Developmental psychologists and social psychologists have been very open to the work on the emotional brain. The developmental psychologists are interested because of the early development of the amygdala before conscious memories kick into play. Social psychologists are interested because the amygdala seems to do its work unconsciously. There's a whole industry of social psychology dealing with unconscious emotional perception, how you use subtle cues that are given off even when you don't know you're giving them off, and how these are picked up by your unconscious mind, so your unconscious mind and my unconscious mind are talking back and forth to each other without our conscious minds knowing anything about it. They're interested in all this work on the amygdala and the possibility that it's an unconscious emotional processor.
Cognitive scientists previously banned emotion from their field, but are beginning to realize that they don't really have a science of mind as such, but instead a science of a part of the mind. They now want to bring emotion and cognition back together, and that's a good thing. Lots of AI modeling of emotion, and some connectionist modeling, is also going on.