Brenda Milner, a neuropsychologist at the Montreal Neurological Institute (MNI), is widely recognized for her studies on memory with the patient known as H.M. [see story, “Tracing Permanent Memories”] Milner, 91, won the International Balzan Prize in cognitive neurosciences last year and is an active member of the research community at the Institute. She is currently overseeing the planning stages of a research project tracing the connectivity between the two hemispheres of the brain.
Milner: It was just luck, really. Psychology as a career subject was non-existent in pre-war England. I went to Cambridge to do mathematics. I thought mathematics was just pure reasoning and I could reason as well as anyone else, but in higher mathematics you have to have special skills, perceptual skills. When I got to Cambridge I realized that mathematics wasn’t going to work out for me.
I had a chance to change fields at the end of the first year, and I thought, ‘I’ll do philosophy!’ And then people from my college said, ‘Brenda, don’t you have to earn a living?’ (I was as poor as a church mouse then, I was on scholarships.) They said, ‘No one ever learned a living doing philosophy, so forget that!’ And now comes the real bit of luck. In England, in Cambridge pre-World War II, experimental psychology was grouped with philosophy and ethics, under the “moral sciences.” Since I had mentioned philosophy, they suggested psychology because [as a psychologist] you could always get a job as a factory inspector.
Then I discovered I was good at it. I was a good observer and I enjoyed working with people in the lab. But it was luck, you see. I didn’t even know what psychology was!
I wasn’t particularly interested in working on memory when I first came to the MNI, in June 1950, I was interested in problem solving and perception. I was working with Dr. Penfield’s temporal-lobe patients—patients who had had unilateral removals from the temporal lobe in the left hemisphere or the right hemisphere—and it was my job to try and find out something about them. I was looking for visual effects from temporal lobe lesions.
My work was being guided by what I could learn from experiments in animals and I knew about the effect of bilateral temporal removals in the monkey. But then the patients with lesions on the left came to me and complained about their memories. Remember, these patients were young, their average age was in the twenties, so they should have had reasonably good memories. They complained that they couldn’t remember things, and it was always things that were verbal—things that they read or things that they heard. They weren’t forgetting their lives or people’s faces or anything nonverbal. Then I found the corresponding thing for the right hemisphere, that is, inverse problems with memory, problems with remembering faces, places, and tunes etc. So I thought, I am going to have to study memory.
I gave him standard intelligence tests and memory tests, the sorts of things I had done with Dr. Penfield’s patients, and I would talk to him, distract him and give him numbers to remember and so on. H.M. (Henry Molaison) could pay attention and had no problem with immediate memory, but as soon as he was distracted, he would forget what had happened before. So you could make this general prediction [about H.M.] that he’s going to forget everything, but no psychologist is happy with this sort of statement—you can’t test a null hypothesis. The challenge was: with practice, with repetition, could he learn something?
I went to the McGill psychology department and borrowed learning tasks to give him. I took down a maze task, which I was sure he wouldn’t learn, and he didn’t. It was a nice control test, because he showed absolutely no progress over three days. Then I gave him the mirror drawing task. H.M. did 30 trials over three days and at the end of the last trial, his performance was absolutely perfect. I can still remember him looking at what he had drawn, saying: “This is strange. I thought this would be difficult, but it looks as though I’ve done it rather well.” I was very excited because it showed that he could have this excellent performance without any awareness that the reason he was doing so well was that he had had the chance to practice the task over three days.
When I saw that H.M. had this beautiful learning of something he had no memory of having acquired, I then speculated that this task, which involved motor learning, depended on a different system in the brain. His surgeon had damaged his medial temporal system, but this was a kind of learning that was unaffected by this operation, so therefore it must involve other structures.
I didn’t find it awkward to work with him; he was always very pleasant and cooperative. H.M. knew he had had the surgery, because he could remember discussions leading up to it, and he had always had this wish to be helpful to medicine. He wanted to help.
You have to remember the reason why he had the surgery. He had had these terrible seizures. Not all epilepsy is dreadful by any means, but this was. He was on the maximum doses of whatever medication was available in those days and in spite of that he would have these major convulsions plus lots and lots of little attacks. It took him ages to finish high school because of this, and then the only job he got was in a factory. And he was having trouble keeping that because he would be falling so often. So this was a terrible life.
I used to say, when I lectured about H.M., that although the surgery controlled his seizures it was at an unacceptable cost. Sue Corkin, a fellow researcher and former student of mine who also studied H.M., challenged me on that a year or so ago. She said, have you thought about what would have happened to Henry if he hadn’t had that surgery? He would have been in a back ward in some psychiatric hospital, he would have deteriorated, and he probably would have died long ago. Instead he lived to be 82, and in his own way enjoyed what he was doing. And I think in this case that she’s right.
It makes for good scholarship—it’s important to have excellent neuropathology on a patient of interest, in terms of the case history, that’s perfect—but I don’t think it’s going to teach us anything new about memory. That’s my personal view.
The important thing was the first MRI that was done. It showed that Dr. Scoville had done exactly what he said he was going to do. It was a beautifully symmetric removal. It wasn’t more in one hemisphere than the other, and it took the entorhinal cortex, the anterior hippocampus, and the amygdala, but it spared the posterior hippocampal gyrus. The important thing was that it did not damage the neocortex, so we knew we were really studying the effects of a bilateral medial temporal-lobe lesion. [The Dana Foundation funded part of the project to create the H.M. brain scans.]
There is a great deal of interest in the different types of memory and how they relate to different systems in the brain. People are living much longer now than when I was a student in 1936. They are not succumbing to diseases that used to carry them off, and so they are getting Alzheimer’s or other sorts of dementia that are affecting their memories. And we all have memory problems not related to age. We are leading busy lives, trying to handle different mental activities. This is one of the things that make people anxious about their memory, but it’s just that they’ve got crowded minds. There is a lot of interference, and I think interference is a huge factor in whether we remember or forget. At the same time, neuroscience has made big advances in understanding memory. The fact that people can now genuinely look to neuroscientists for advice and help, well, it keeps a duet going between the public and the scientist in a profitable way.
It’s also spilled over into in popular culture, in the cinema and other art forms that get communicated to the public, so that helps to make it a hot topic. Once you start studying memory you are really studying so many different dimensions. We are our memories. Of course we aren’t only our memories, because you can have memory problems and still show the same personality to others that they’ve come to expect from you. Are you an extrovert or introvert? There are all these different personality variables that are not a consequence of your memory, that are genetic. But this is another dimension.
I wish I could take credit for it but it’s just my genes, I think. My mother worked until 88 and lived to be 95, and she was always very mentally and physically active. I have always walked everywhere myself, I never drove, never had a car. There are many things that can go wrong with our brains as we get older, but by keeping active we can help put that moment off.
A lot of it is technology. I don’t think the interest in the brain and behavior is new, but people had the sense not to ask questions that were impossible to answer. You don’t ask how to get to the moon without the technology. Now with these developing techniques, you can indulge your curiosity more and more. The curiosity was always there, of course.
The field is attractive to people and there are so many bright young scientists that I think there will be an explosion of knowledge soon. It would be very exciting to be young in this field today.
I was starting out in what was really a brand new field, though I didn’t know that was what I was doing. I would never have been brave enough if I had thought of it that way! But in a way I was one of a few pioneers, there were some in Western Europe and a few in North America, who started something.
That’s what makes it exciting to talk about the history—I’ve lived not just through the history of my own life, but also of the life of my field. Neuroscience has grown incredibly over the past 50 to 60 years. It’s a flourishing industry.
People who were guessing where things were going fifty years ago probably guessed wrong—it is difficult to guess. Some serendipitous discovery could potentiate a whole line of research that we can’t even imagine at this moment. What would interest me would be to get a better idea of the actual neural networks that correspond to some of these learning processes. In terms of understanding the networks of cells, we are nowhere near there. That would be nice, that would be really nice.
[This interview has been condensed and edited for clarity.]