Mapping the Mind with Rita Carter (cont.)

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.



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