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| OPEN MIND | |
 October 30, 1998 
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PHIL PONCE: For years, conventional wisdom held that after birth, once brain cells died off, they could never be replaced. But now a new study shows just the opposite, that the body can, in fact, produce new brain cells. Joining us to talk about findings is Fred Gage, a professor at the Salk Institute for Biological Studies in La Jolla, California. Professor Gauge was a lead author of the study, which is published in the November issue of the journal "Nature Medicine." Welcome, Professor. First of all, what did your study find? FRED GAGE, Salk Institute: We found that, in fact, new cells can be born in the adult neurosystem, in particular, regions of the brain.
FRED GAGE: I think there was a dogma that had developed over time that grew out of some assumptions that have not been experimentally tested. And what we did was to determine or experimentally test whether or not this phenomena really was true or not. PHIL PONCE: And, Professor, what kind of cells are you talking about? FRED GAGE: Well, we're talking about an area of the brain called the hippocampus, which is a structure that's involved in learning a memory, which has a specific layer of cells called the granule cells. They are the primary relay station for information coming in from the cortex, and these cells, along with the other cells in the hippocampus, are involved in organizing information as it comes into the brain before it's sent out back to the cortex, where it's stored. PHIL PONCE: And, Professor, give us an example of the kinds of things that this part of the brain - what kind of a function - an example of the kinds of functions that this part of the brain performs.
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Cell Markers. |
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PHIL PONCE: Professor, you talk about the cells - you just mentioned the term "circuitry," for example. These nerve cells - I read one article that referred to them as helping to form what is considered the circuitry of the brain. Is that a fair characterization of the kind of cells you're talking about?
PHIL PONCE: Professor, I understand that you discovered that this was happening - and I wrote this down just so I could get it straight - you established this through autopsy specimens, people who had been given a drug that leaves a marker on new cells, and you found these markers in the brain. What was your reaction when you realized what you had found? FRED GAGE: We went into the study with the plan of using this methodology, which was being used both experimentally in experimental animals to find out whether or not and to study how these cells were being born in experimental animals. At the same time this rug was also being used in patients to mark cells that were undergoing cell division. So what we decided to do with our colleagues in Sweden - P.D. Ericson and his colleagues - was to attach our study to an existing study that was already trying to mark the rate at which tumor cells were dividing in these patients, received permission from the patients to obtain autopsy material so that we could assess whether or not the cells that were born at the time of the injection would subsequently have developed into neurons. This required - PHIL PONCE: By neurons you mean nerve cells? FRED GAGE: I mean nerve cells exactly. PHIL PONCE: And given the conventional wisdom that existed before this, a bit of a surprise, I take it? FRED GAGE: Yes. I would say that we were - we were not confident that we would absolutely find these cells, and that's why did the study - was to determine whether or not we would.
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The repair process. |
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PHIL PONCE: So, Professor, the medical implications one hears about possible ramifications for people with Alzheimer's or Parkinson's or brain damage due to trauma, how do you assess the possibility of that? FRED GAGE: Well, for us, the major task ahead is to find out how the brain actually allows for these cells to persist. And they're persisting in a very immature state until they differentiate into neurons. And we need to learn how they survive, how they go through the process of differentiating into neurons. If we can learn the cellular and the molecular controls that allow this process to occur, we might be able to apply that information then to situations of nerve degenerative diseases or trauma. But it will be predicated on really understanding the underlying mechanisms involved in this process.
FRED GAGE: I think you're absolutely right. Over the last 10 years there has been a striking amount of information that has been gained about the brain, and it has resulted in our changing views of the brain and its ability to adapt, to changes in the environment. We use a term "plasticity" as a description of the adaptability of the brain to its - to its environment. And this growing knowledge allows us to actually discover the mechanisms within the brain that are changing as a function of our interaction with the environment. PHIL PONCE: What do you say to people who perhaps have Parkinson's or have had brain damage, who look at these studies and think, great, something is on the horizon? FRED GAGE: Well, I think that people can take heart in the fact that there are many investigators now that are taking very seriously the idea that the adult brain retains a lot more ability to attempt to repair itself. And as we gain more knowledge about these changes in the brain, we hopefully will be able to aid in this repair process ourselves. PHIL PONCE: Professor Gauge, thank you very much. FRED GAGE: You're welcome.
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PHIL
PONCE: And this was something that simply had not been believed before,
that the brain was capable of generating new cells? 
FRED
GAGE: Well, the brain is a - the hippocampus, as I said, is the structure
that's involved in learning and memory, and it involves processing new
information, as opposed to storing information. And I think this is
where some of the confusion may have arisen in the past, was the idea
that the brain couldn't add new cells because it may disrupt existing
circuits and perhaps disrupt existing memories. The hippocampus is a
unique structure and not involved necessarily in the storage of information
but more in the processing of new information.
FRED
GAGE: Nerve cells are a unique cell population in that they connect
with not just the cells that are next to them, but they have processes
that elaborate and result in communication with cells quite a far distance
away. So when we talk about circuitry, we talk about the processes -
we mean the processes that extend from the cell and connect one cell
with many other cells within the brain. 
PHIL
PONCE: Professor, we reported earlier in the show that another report
of Harvard scientists - who've developed a new way to grow human brain
cells for use in transplants - and by the way we incorrectly - we gave
the incorrect source for that. It's actually the publication "Nature
Biotechnology." But, does this reflect perhaps a view that there is
a change in the way the brain is being perceived, as perhaps more malleable,
more subject to manipulation?