Torsten N. Wiesel


Interview, December 2001

Interview with Dr. Torsten Wiesel by Joanna Rose, science writer, 8 December 2001.

Dr. Wiesel talks about his studies of the visual process in the brain; challenges in neurophysiology (8:21); colour vision and the perception of the world (11:01); and his present work in helping to train students from the developing countries (14:49).

Interview transcript

Welcome to this Nobel interview, Professor Torsten Wiesel. You have devoted your long career in science to studies of the visual processing in the brain and now we can say, and we know, that this is not a simple thing, a simple process, rather a result of a long process that begins in the eyes but definitely does not stop here.

Torsten Wiesel: Correct. Of course it’s a very complex thing you’re asking the brain to do, because we can see details, colour, depth, moving objects, etc. Your camera cannot move without getting a slur in the image that is unclear, whereas your eye can move from one part of the room to another and still everything is clear. So this is a very complex machine that can carry out all these various functions, and we are, I think, still at a relatively primitive stage of a complete understanding of the neuro basis of perception. So it’s a long way still to go even if progress has been made.

So this is not just a mechanical process? It is a question of interpretation?

I used to say to students it’s not like a fax machine, that you send an image up to the brain …

Torsten Wiesel: Right. The brain has to decompose an image that falls on your retina and there are hundreds of millions of receptors in your eye, photo receptors that are sensitive to light and then there’s only one million fibres going from the eye into the brain. So already in the eye there’s some processing, complex processing of the image and then that’s sent into the brain and then it’s further composed together so that you can see all the things in detail. I used to say to students it’s not like a fax machine, that you send an image up to the brain and there are little people looking up in the brain at that picture, because you actually have to decompose the picture, send it like a message up and then rebuild it so you can perceive it and we know some of the code that is used by the brain to carry this out but we are still at an early stage of understanding that process.

In spite of nearly 50 years of studies, I wonder what do you consider as the major step in our understanding of how the visual system works during these years.

Torsten Wiesel: During these last 50 years?

During your career, I would say.

Torsten Wiesel: During my career … You know, I came into a laboratory at Johns Hopkins University at the time. My mentor there was a man by the name of Stephen Kuffler and he had studied cells in the eye that leave the eye going to the brain and learnt about the way that these cells decode the visual image. Also the Swedish scientist by the name of Ragnar Granit was also very important in vision research and he received the Nobel Prize in 1967, I believe, for his work on the eye. My colleague David Hubel and I, we were fortunate when we started, in 1958 we started to work together, and try to understand how images sent in from the eye are handled by the brain and so that was some advances made during our collaboration. We worked together for 20 years in trying to understand how the first and second stage in the brain handle visual information and particularly in the visual cortexes, a primary visual cortex, it’s called.

But even after the Nobel Prize you continued your research?

Torsten Wiesel: Yes. But you ask for the last 50 years with advances. So the reason why we got the Nobel Prize was because we made some advances obviously, and that was part of what I said, the decode, the fact that cells in visual cortex respond to contours of given orientations. So that then a phase, for example, is decomposed and then rebuilt perhaps cells responding to different orientation of your facial contours will feed and assemble cells responding in a particular way and the advances since that time scientists have recorded from higher visual areas, because first the signal from the eye goes to the primary cortex, then the second, the tertiary higher structures and we don’t have to go into the details, but at some stage, maybe three steps away, there are cells that actually respond to a face.

Not your face necessarily, but any face that is contoured like a face with eyes and nose and a mouth; those basic characteristics. So that is a major advance in the sense that cells can be so specific that they can respond to a particular object. There are probably other cells responding to a face or a form or shape. Of course these cells you’re not born with necessarily, because there’s a certain plasticity in the brain so that you can not only learn to recognise a new face but also objects which you never knew existed, like in modern art, for example, sometimes you see very abstract things which are invented by humans and you still can see them, recognise them and sort of store them as a visual memory like you store a face.

But still I am not born with the cells that are focussed on modern art?

Torsten Wiesel: You’re born with the machinery to learn how to build an image. So these cells are sensitive to contours.

Very flexible machine.

… some part of our brains remain flexible all through life so you can learn new things …

Torsten Wiesel: You’re born with those cells. The newborn child can disseminate colour, it can see things, objects and so on. There’s a certain basic thing we are born with, but then of course you learn a lot of things. You recognise chairs and all kinds of things. So some part of our brains remain flexible all through life so you can learn new things, not only in vision but in language and movement etc.

The field of brain studies has developed tremendously since you entered it in the ’50s. What do you find is the most interesting challenges in neurophysiology today?

Torsten Wiesel: Neuroscience is advanced to a large extent because new ways have developed to study subjects.

New instruments or new ways of thinking?

Torsten Wiesel: New instrumentation. Both new instrumentation and new conceptual questions perhaps asked. Sometimes you ask questions now that you didn’t ask earlier because there were no way of getting an answer.

What are these questions?

Torsten Wiesel: For example to ask the question that I said before that we want to understand the neuro basis of perception. That question wasn’t asked 50 years ago as a realistic scientific issue, but today it is realistic to try to actually have an experimental programme that tries to address that question so that’s the difference. And I think, you know, there are some people who feel that now it’s the right time also to understand not only neuro base of perception but also the higher issue of consciousness in general because in order to have perception you have to be conscious otherwise you don’t perceive. So those two are obviously linked very much.

So if you want to address a question of consciousness, then perhaps you have to do it in a context of a specific issue, like vision where you have a perception. You can when we know more perhaps about the sensory part of the brain in vision than in the other part of the brain because there has been a lot of interest, a lot of people have studied the various stages of the vision system both in psychophysics and in the laboratories, anatomy, physiology, chemistry etc. So there’s a lot of knowledge here, so I think the next decades in the future you are going to see more and a better understanding of the perception and consciousness related to that.

Yes, there is this question, for example, when I see this flower and I see the red colour here, I recognise the colour here, I call it red. How can I be sure that the red colour that you see is the same that the one that I see? Do you think that neurophysiology can answer such questions?

Torsten Wiesel: Yes, of course it’s been known for a long time that colour vision varies between individuals because it depends very much on the visual pigment you have in your eye.

So maybe your red is my green, for example?

Torsten Wiesel: Most people have, not so much, but we have the cones; we have red, we have blue and we have green cones and they have their own spectre of sensitivity. Most people have very similar spectres and sensitivity of their cones but there are variations. So some in the red cone and maybe a slight difference in the peak sensitivity of the red cone, somebody else may have it in blue. So there may be slight variation, but then there are mutations. There are people who actually have no red cones or blue cones or green cones, so they have specific colour defects and it can be dangerous if you’re in the traffic and you know the red light and you don’t see red light and you have to know that the red is on top and the green is below.

So I think one has to assume that in most cases our perception of colour in this bouquet of flowers is probably similar, even if maybe somebody else would have a clear difference. I have a painter friend actually who had a deficit in his colour, his vision and his paintings reflected that. His colour scheme was kind of strange and some people found it very interesting but, you know, that was based on the fact that he saw the colours different from you and me perhaps.

Yes, perhaps. But there still is this problem of consciousness of the subjective perception of the world. It’s sometimes called explanatory gap, how can our emotions and our perceptions translate into the hardware of the brain. Do you think that neurophysiology can jump over this gap or fill it in?

You have a knowledge here, up to this point and then you need to know more …

Torsten Wiesel: Knowledge advances in science at least, usually step by step, and depending on your background and the literature you read you may feel that there is a gap but some of us may feel there is no gap. It’s just a feel of ignorance. You have a knowledge here, up to this point and then you need to know more. You’re ignorant, you don’t understand something else and to have a complete basis for perception let’s say, because that’s what we’re talking about. So you can see that as a gap and it certainly is a gap in our knowledge but it’s not the conceptual gap.

I have one last question about something else. You have left the research now and you have recently focussed your interest on other issues than doing research I would say. What engaged you most by now?

Torsten Wiesel: You know I was a professor at Rockefeller for a number of years.

Rockefeller University in New York, yes?

Torsten Wiesel: Rockefeller University in New York and I had been in Harvard. David Hubel and I worked together most of our time at Harvard, started out at Hopkins but then as a professor there was a need at a university so I was asked by the Board of Trustees to become president of that institution. It was in December ’91 and so I accepted to do that. So I did it for seven years. During that period it was very difficult for me to do experiments and I was 67 years old at the time. So after seven years I was close to 75 and the question was what … I was still full of interest and energy so instead of going to the laboratory I continued expanding, I should say, my interest in trying to help young scientists to have the same opportunities I had as a young scientist and to try to help to train students from developing countries.

You mean to move from one country to another to come to good laboratories?

Torsten Wiesel: Yes, I’ve been running a programme for Latin American students, supported by the Pew Charitable Trust for ten years, bringing ten students a year from Latin America to come to the United States for training. Another interest I have … I’m now Secretary General for the Human Frontier Science Program which has headquarters in Strasbourg and we gave about 140 fellowships a year to students from all over the world, from 60 different countries.

As stipends for studies?

Professor Torsten Wiesel Stipend for studies. It’s now a three year programme and most of the students come to United States for studies and many of them stay in the United States because opportunities to do science there are usually better, particularly in the developing countries and I’m very interested to try to change that pattern so that we can help to provide opportunities for good training but also provide opportunity for young people coming back to their home country to carry out similar type of research as they did doing the training.So this is a major challenge I think that one should make serious effort.

… it’s difficult for young scientists to be independent, to get funds to do their own research …

It’s also provided opportunities, even in developed countries, it’s difficult for young scientists to be independent, to get funds to do their own research because Europe and also in Japan the professor is still taken very seriously whereas in United States a professor is not taken so seriously and the custom there is that as a young professor, assistant professor, you get your own lab, your own money and you’re doing your own research whereas in Europe and many part of the world it’s still not the case, you are still an assistant to the professor rather than independent scientists. This is an issue that I find very important for Europe and other parts of the world to develop really good science. It turns out the reason I think for the American success has been money but also the way science is organised.

So you want to spread the idea of organising science because you yourself were born in Sweden but you have had your career in the States.

Torsten Wiesel: My scientific career in the States, yes, in part because of circumstances I had very good collaborator with David Hubel, we worked very well together. So that was one temptation. In science America became my homeland whereas when I come here I feel very much at home but it’s not as a scientists, it’s more as a person, a private person.

I understand. I wish we had more time to discuss these issues but thank you very much for the interview.

Torsten Wiesel: My pleasure, thank you.

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