Mapping the Mind with Rita Carter

Last Editorial Review: 10/23/2003

WebMD Live Events Transcript

Medical journalist Rita Carter will discuss how our personalities reflect the biological mechanisms underlying thought and emotion.

The opinions expressed herein are the guests' alone and have not been reviewed by a WebMD physician. If you have questions about your health, you should consult your personal physician. This event is meant for informational purposes only.

Moderator: Welcome to WebMD Live. Today we are discussing "Mapping the Mind," with Rita Carter.

Rita Carter, a distinguished English medical journalist, is the co-author of Mapping the Mind. For the past ten years she has been a medical and science writer. She has contributed to a wide range of newspapers and magazines, including the Independent, New Scientist, Daily Mail and Telegraph. She was twice awarded the Medical journalists' Association prize for outstanding contribution to medical journalism.

If you would like to ask Rita a question, please type /ask followed by your question (e.g. "/ask how are you?")

Rita, welcome to WebMD Live.

Al_Pavy_WebMD: What motivated you to write Mapping the Mind?

Carter: I became fascinated in the new science of the brain about ten years ago when you first started to see those little PET and fMRI scans which started to appear in the newspapers occasionally. They are little pictures of the brain's activity when people are doing particular things, like thinking a sad thought or doing a particular mental task like adding up figures. It seemeD to me that these brain scans were a revolutionary thing because for the first time, it was possible to actually look inside a working, living brain and see what it was doing and how it worked instead of having to guess what was happening in the brain by way people behaved. That was all we had to go on before that. As these pictures started to come out of the brain laboratories, they were putting out little snippets of information but I could find no one who was putting them together like a jigsaw to make a big picture. I started to collect these bits of information and realized a picture was starting to emerge, a new type of view of the brain. Nobody else had written the book. I thought I would write it myself.

Moderator: Do you have a medical background?

Carter: No. Everyone asks me this and assumes that I have some sort of scientific or medical background. In fact, I'm a journalist, a medical and scientific journalist and I think it is an advantage because what happens when you get onto technical subjects like the brain is that people who are highly qualified scientists get so used to technical jargon that they forget that most people don't know what the terms mean. Because my background as a journalist is explaining technical things to people without the background, it helps not to be over-qualified myself because I automatically have to find out what these terms mean and translate them for myself before I write about them. There is no danger that my stuff becomes jargon heavy.

Al_Pavy_WebMD: What is the difference between men's and women's brains?

Carter: This is very controversial. It is at the moment, rather politically incorrect to talk about these things, it seems. We have a strange situation in which scientists seem to be very reluctant to carry out the work that would answer that question because I think they are frightened of what they might find. They did not want to be accused of sexism. At the moment, they can legitimately say that there is very little data on this subject. Of course, the reason there is so little data is because they do not want to go out and get it. However, there have been a number of studies that have demonstrated distinct differences in male and female brains. One of them is in simple anatomy. The brain, like the rest of the body, is molded largely before birth by the action of hormones in the uterus. Male fetuses get exposed to much more testosterone and brain tissue is very sensitive to testosterone. The hormone actually molds the brain of a male to make it anatomically different in small but important ways from that of a female. One way is that it kills off some of the connections between various bits of the brain. This means that the male brain is less integrated. There are fewer neuro connections between the two hemispheres. This means that less information flows between the two sides of the brain. These differences are small but in a large population sample, they become significant. The result of this particular difference is that it makes men and women treat problems in a rather different way. Because men's brains are more localized, if they are asked to do a problem, they will bring to bear on that problem very precise and localized brain skills. For example, if they are asked to do a complicated problem involving mathematics, they will just use that bit of the brain which has evolved to do mathematics. Women might use the visual part of their brain to visualize the problem or will pull on memories to help them solve the problem. They have a more creative or lateral way of thinking whereas men tend to be more incisive and logical. These are very small differences. You can only discover them when you start to do experiments using large numbers of people. The differences between the sexes are much smaller than the differences between two individuals but they are real. There is no doubt about that. There also seem to be differences between the emotional brain functions of men and women. Again, because women's brains seem to have more lateral connections, if a memory arises in a woman's brain, it is more likely to produce an emotional reaction because the connections will go into the emotional areas of the brain whereas a man might not make those connections. These differences are amplified, I think, by the culture that we live in. It is probably not true to say that the observed differences between men and women, that is the conventional, stereotypical things about the sexes, are entirely due to biological reasons. I do believe that they are at the root of them.

blaine1_WebMD: so what should men know that will help them to better understand women?

Carter: It might help to recognize that women are thinking in a broader way about things which you might think are very specific but a woman might be pulling on all sorts of peripheral implications. For example, if you say "do you remember when we went for a moonlight swim and the fish we saw," you should remember that she might not just concentrate on which kind of fish you saw, she might also be thinking about the romantic situation that occurred there or the argument you had before or all sorts of other things which are associated with that. That might bring about a curious reaction which you might not understand given that you were interested in the fish. You should also understand that women, in general, are very bad at reading maps. This is because the bit of the brain which is concerned with map reading is not very well developed in women compared to men. However, women are very good at asking directions because the bit of their brain which is concerned with communication with other people is very well developed. Perhaps if couples recognized this, there would be fewer arguments when people are in cars together.

Moderator: So are these differences in memory or perception socially based, or biological?

Carter: I think like everything else about these differences, what happens is there is a small biological difference which is innate. The culture amplifies these small differences and feeds back. It is like an interactive system so what might begin as a minute biological difference can be made into something huge because it is reinforced by society. Therefore a society which very deliberately does not amplify such differences stands a better chance of allowing its citizens to develop their natural, biological, selves rather than being forced into stereotypical roles.

Moderator: If a society doesn't "impose" roles on people, would a person's brain effectively develop differently, in a physical sense?

Carter: Yes. The brain is exquisitely sensitive to everything. That includes all social and environmental factors. If you live in a society which constantly emphasizes one part of your sexual role, for example, if you were a man living in a society which was very aggressive and encouraged men to be aggressive, that part of them which is potentially aggressive will be encouraged to develop and just like a muscle in your body will develop if it is exercised, so a bit of your brain will also develop, quite literally physically. If, for example, you use the part of your brain which processes music, it has been shown that you can develop up to 25% more brain tissue in that area just by practice. Similar studies have not been done on the influence of aggression in humans but in rat studies, it has been demonstrated that rats which are in a social context in which they are encouraged to act aggressively actually do have anatomical changes in their brains as a result of that.

Moderator: Have any physical studies been done on the biological differences in brain develop across cultural lines?

Carter: No. I think the practical problems of getting people from some obscure Brazilian tribe to come and do strange exercises in an MRI scanner, that is too difficult at the moment though I'm sure it will be done. As for looking at the brains of primitive peoples thousands of years ago, the brain does not leave any fossils and it's very difficult. Some interesting work has been done on looking at shape of skull and relating that to what must have been the shape of the brain. Because we now know which bits of the brain do what, it's possible to look at these fossil skulls of ancient people and deduce from the shape which bits of the brain were least developed. The frontal lobes of the brain were a recent development and we now know that it's in the frontal lobes that we carry the capacity for all those functions that we think of as being most essentially human. The ability to form concepts, to experience subtle emotions, to plan ahead and to juggle concepts in a way that allows us to be creative. From that, we can deduce quite a bit about what those people must have been like.

Moderator: How do we know that only humans have these "human" abilities? How do we know chimpanzees can't conceptualize?

Carter: What makes the human brain capable of its extraordinary feats of conceptualizing and creativity seems to be dependent on its ability to create language, not just the ability to use words as gestures or to sign concrete ideas. The ability to use language to form concepts in a way language is a vehicle for concepts. Language has a very specific bit of the brain associated with it. It is not a whole brain activity. It is very localized. In most people, it is a bit of the brain on the left side which holds this capacity. And there is very little evidence that this bit of brain has yet evolved in anything but a few of the higher primates. It is noteworthy that those primates which are showing this very slight development in this bit of their brain are the same ones which have been shown to have the highest conceptual abilities including the crucial ability to have a notion that other people have a different point of view from them. It is that distinction between self and other, and the ability to put yourself in another person's shoes which is the springboard for all conceptualization. I don't think it is simply being ethnocentric. On the other hand, it does not follow that because human beings are in these ways so much more advanced than animals that we are any better because the ability to put yourself in other people's shoes also gives us the ability to be deceitful.

Billy_de_WebMD: What are the particular parts of the brain (anger, taste, etc.)?

Carter: To take those three examples, anger is generated by a tiny nugget of tissue which is buried quite deep in what is called the limbic system. This area is not in itself conscious but it is the seat of our emotions. This seems a strange idea because we are used to thinking of emotions as being conscious feelings but, in fact, the consciousness of an emotion like anger is only a secondary effect. Emotion itself is primarily a bodily reaction to an outside stimulus. If something comes into the vicinity which is threatening, the bit of tissue which generates anger is called the amygdala and every stimulus that comes in through our sensory organs passes through the amygdala. If it is dangerous or threatening or in any other way signficant, the amygdala will be activated. It will start to light up like an alarm. When this happens, it sends signals to the hypothalamus which is very close to it. That part of the brain sets in motion a huge bodily reaction which results in all the familiar feelings of anger or fear -- butterflies in the stomach, weak knees, heart beat thumping, and so on. In human beings, however, it has a second effect. The amygdala is also very closely connected by neuro pathways to the frontal lobes of the brain and when it becomes active, it sends messages up these pathways to the frontal cortex which is what makes them into a conscious feeling. That is what produces what we talk about as anger. In people who do not have these neuro pathways, for example, some types of psychopath, the get the physical reactions but they do not necessarily get the conscious feeling of anger. Something like taste is a more sophisticated brain function. The more sophisticated that is, the later evolved in us. The more likely it is that they are situated in the cortex, that is the outside gray tissue which is where consciousness arises. Taste is an amalgam of a very primitive function which is smell and a much more complicated development which allows us to distinguish very finely between different types of food, good things and bad things. It is the one of the most complicated of brain functions and it is distributed in at least three different bits of the brain. One of them is right next to the bit of the brain which registers disgust. This makes sense if you think about it because disgust is essentially the reaction that we have to something which we want to reject and it evolved from the reflex of spitting out something that was consumed which was bad for you. That is why if you ask somebody to think about something disgusting when they are having brain scan, that part that lights up is right next to the bit of brain that lights up when they are asked to taste something.

Moderator: Does this "disgust" extend to the sense of moral disgust at someone's behavior or action?

Carter: Yes. It seems that all our ideas of revulsion all stem from this very physical type of rejection of things which are bad for us. If you put somebody in a brain scan and told them about the behavior of someone who had done something morally disgusting, you might well find that the bit of brain which is normally associated with disgusting food or smell will light up. These things are very similar. It's just that human beings have extended them into much more complex areas.

the_ref_WebMD: What sort of thing dictates what makes one person angry (or happy or sad) and does not have the same effect on another person?

Carter: Although the crude map of the brain, that is the location of particular types of functions like taste, language, mathematical ability and so on, is more or less the same for everybody, every brain is also different just in the same way that all human faces have two eyes, a nose and a mouth in the same formation and yet no two faces are identical. The brain is more plastic than any other bit of the body and because it reacts constantly to outside stimuli, it is able to re-wire itself in an individual way according to its personal experience. On the whole, it will react in much the same way. That is why we all have a common culture where we agree that certain things are good, certain things are bad, certain foods are good, but within that broad spectrum, there is room for great individuality and that comes about by minute differences in neural connections which are formed by a person's individual experience. If your first experience of caviar is to feel that it is disgusting, it is only if you are encouraged to try it again and somebody else tells you that this is good that you start to get the idea that it might be good and will retrain your taste. If you are constantly told that something is bad, you will genuinely feel it is bad. Environmental factors can have a very large effect on what you end up feeling and thinking and experiencing. Nobody has yet managed to quantify that. It's the old nature/nurture argument. It's complicated when you come to the brain because it could be that certain brain functions are susceptible to environmental factors. Things like sexual orientation seem to be hard-wired by birth because sexualization of the brain happens before birth. You can break sexualization into number of areas and each has a physical bit of the brain associated with it. The hypothalamus has a particular group of modules, each of which is responsible for a different aspect of sexualization. One of them, for example, decides the degree of libido that a person is likely to have in later life. Another is responsible for the orientation, that is whether a person will be attracted to their own sex or the opposite sex and another will decide whether they fulfill stereotypical expected behaviors. You can have any of these combinations of sexual orientations according to the degree that these bits of the hypothalamus have been stimulated largely before birth by the action of hormones. If the bit of brain which is responsible for sexual orientation is highly stimulated before birth by testosterone, it effectively hard-wires that person to be heterosexual it seems. It is unlikely that any amount of environmental programming would alter that sexual orientation. Certain things are very hard-wired at an early stage. Things like your taste for fish, on the other hand, might be very much to do with your early experiences with eating fish. Some things are very flexible and very much to do with nurture. Other things are very much to do with nature.

Moderator: So this is a very controversial area of study?

Carter: This is a very controversial subject and rather like the experiments on brain differences between the sexes, the whole nature/nurture is something that many scientists try to steer clear of because it has such wide implications.

infaymous_WebMD: How do practices like meditation, yoga and chanting affect your brain and its chemistry?

Carter: There has not been very much work yet on the effect of meditation and related practices on the brain. People are now starting to do it. One of the things that meditation does is to close down the activity of the amygdala, that part of the brain which generates fear and anger and negative emotions. It is this that probably produces the calmness that is typically seen in people who meditate regularly. It probably also stimulates the release of certain neuro transmitters such as dopamine which is the chemical which gives us a feeling of pleasure and seretonin which tends to make us feel serene. Nearly all of these disciplines, yoga and so on and even prayer, seem to be directed at producing similar brain changes, physical brain changes. The other thing about them is that there is some evidence to suggest that it shifts the balance of activity towards the right hemisphere from the left. The left hemisphere tends to be very concerned with time, with planning, with verbalizing, with logical thinking whereas the right hemisphere produces more of a feeling of timelessness and serenity. That too might account for some of the results of practices like meditation.

Moderator: Rita, this is all so interesting...Have you any final thoughts for us?

Carter: A lot of people do not like this very physical, biological approach to brain sciences. They think it reduces people to robots, mere objects, but I think that by starting to get to understand the mechanics of the brain, it will ultimately allow us to understand the more interesting and ultimately more meaningful things about the human mind.

Moderator: Thank you for joining us today, Rita. WebMD Members, please join us every Friday at 1 pm EDT here in the Body Beautiful Auditorium for our live weekly event. Next week, we will be discussing Breakthroughs in Rhinoplasty for the New Millennium with Steven Herman, MD, F.A.C.S.

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