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B R A I N S C I E N C E P O D C A S T
with Gi n g e r Campbell , MD
Episode #54:
Michael Merzenich on Neuroplasticity
Aired February 13, 2009
"If there's an aspect of this that's important, I think it is the lesson that most changes that are occurring in brains when brains are losing functionality are reversible. Or, from a child perspective, most of the limitations that are recorded in the brain of a child in fact are improvable."
-Dr. Michael Merzenich
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"Whatever you struggle with in a sense as it stems from your neurology, the inherent plasticity of brain gives you a basis for improvement. This is a way underutilized and under-appreciated resource that we all have."
-Dr. Michael Merzenich
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The following in an excerpt of the interview with Dr. Merzenich.
click here for the full podcast. Click here for the full transcript.
Ginger Campbell:This is episode 54 of the Brain Science Podcast. Today I am talking with Dr. Michael Merzenich, who was one of the pioneers in the field of neuroplasticity. He will share some of the highlights of his long career with us and give us some practical advice about how we can continue to tap our brain's plasticity, whatever our age.
Ginger Campbell: I want to welcome my guest today to the Brain Science Podcast- it's Dr. Michael Merzenich. Well I've talked about your work a lot on my podcast so it's a great privilege to have you on the show today.
Michael Merzenich: Well it's nice to talk to you Ginger.
Ginger Campbell: The discovery of neuroplasticity is one of the most exciting recent developments in neuroscience, and since you are one of the pioneers in this area, I was hoping that maybe we could start by looking back at the early part of your career and working our way forward.
Michael Merzenich: Sure.
Ginger Campbell: In your career you've had more opportunities, I guess, than the average to make a big impact on patients' lives. I was thinking in particular, also, about your work with dyslexia. I guess that came out of your experience with working with hearing to begin with?
Michael Merzenich: It did, and actually the initial inspiration for that came from studies that were conducted in monkeys. And we were studying aspects of hearing and plasticity in monkeys and we began to realize that hearing processes in monkeys were highly plastic and that we could evaluate the performance of a monkey- these are little New World monkeys from South America. And we'd look at the ability of the monkey to make distinctions about complex stimuli, you could say like speech-like stimuli, and the monkey could be very poor at it initially, and we began to realize that we could dramatically improve the monkey's ability to operate as an accurate receiver of sound by training them appropriately intensely. And we also began to understand that the processes that we were observing were reversible and we could drive the ability of that monkey basically in a way that degraded its capacities to understand what it was hearing or interpret what it was hearing.
In other words, we began to understand that we could probably take you and train you appropriately over a period of a month or two and degrade your ability to understand what I'm saying, or we could turn around that training and probably substantially refine your ability to interpret with high accuracy, especially under difficult conditions, what it is that I'm saying, and understanding that your ability to operate in a domain-like language was fundamentally plastic. That it was subject to substantial refinement if you were less than perfect at it immediately opened up the possibility that we could probably train a child that wasn't very good at it to be better. And we know that a lot of children aren't very good at it, and among those are children, many children, that struggle to learn to read.
Ginger Campbell: I remember when I was in medical school, I got taught a very simple idea of what dyslexia was that didn't involve the auditory component at all.
Michael Merzenich: Right.
Ginger Campbell: Is that pretty well accepted now, that it's as much about hearing as it is about the visual?
Michael Merzenich: Right. The fundamental problem... if you could say there's a core problem that limits reading performance- and all dyslexics aren't identical, but the most common problem is a problem in phonemic reception accuracy. The phonemes are the sound parts of words that bear meaning in words, and the problem stems from the fact that the brain has not created the normal representation of the sound parts of words. So now we're going to try to make a translation of the sound parts of words in terms of their letter forms, and that only makes sense if the brain has done this sorting in the normal way, which basically allows the child to appropriately assign a letter, which is a form of representation of the sound, to it. In the abnormal form of brain operations that apply in the dyslexic, that translation makes no sense. They do not have normal processing of those sound parts of words, and they are not sorted in the same way in the brain. So that translation makes no sense so it's fraught with error and the child struggles to make those relationships- to draw those relationships. We also know that these children commonly have a problem in how they process information serially in fast time. That also is strongly related to their having created this defective representation of sound inputs in their earlier language listening history. So we now know that it's a very large body of evidence which demonstrates that in most children, the core problem is a problem that really stems from language listening, which frustrates this assignment of the letter representational forms to sound.
Ginger Campbell: So you have to learn to listen right before you can learn how to read.
Michael Merzenich: It's only when you're sorting information appropriately does this translation of- I mean after all, reading is simply based upon the translation of what you hear in a written form. And if what you hear is not represented in the brain in the normal way, it's a very bad representational system. It really doesn't represent what you hear. So unless you correct that- unless you correct the listening, you cannot really generate a reader. I mean you can do it only by using alternative strategies for reading, but you can't use a phonological approach to reading. You have to use a whole-word or other approach- then you can be successful. But you can't use the classical efficient approaches to learn to read. So you have to correct the listening to correct the reading.
Ginger Campbell: And that's how Fast ForWord™ works?
Michael Merzenich: That's exactly what it's designed to do- is to correct the listening.
Ginger Campbell: Do you want to talk about that just briefly?
Michael Merzenich: Well, it focuses on these fundamental core resources just like we would approach the training of a monkey to approach the facility with which it resolves the details of what it hears in order to make it a more efficient and more accurate processor of complex things arriving in hearing in high speed. So too can we train any child to be better in the accuracy and in the speed at which it receives and interprets information in his brain through listening. You can improve any normal child, but you can also improve children that are substantially impaired in those abilities and drive most of them to a normal performance level without too many hours of intensive exercise. And you can demonstrate that through such progressive training they can achieve relatively normal or more normal phonological processing that enables reading. So you see big impacts with relatively short amount of time spent in training, both in language accuracy, language reception, and language usage and in reading.
Ginger Campbell: Once the child has reached normal do they have to keep doing the exercises or is the effect...
Michael Merzenich: No there's a very high retention in ability and it's been measured in several scientific ways. Let me just say that the average gain in language abilities for a child that sits of the left side of the normal distribution below the 50th percentile- the average gain in control gain is about a standard deviation, so that would mean that if the child is at the 16th percentile, let's say, which would mean that they would be on the edge of eligibility for services as a kid that needs special help- special needs kid in most states- that kid on the average is driven to about the normal median.
Ginger Campbell: That's pretty impressive.
Michael Merzenich: And that occurs with about 20 to 25 hours of training.
Ginger Campbell: Over how much time would that usually be done in?
Michael Merzenich: Well usually it's done 50 minutes a day, so it would be about 25 to 30 days spent, an hour a day- 50 minutes a day. And then the second thing that's seen is that if the child is behind in reading, the gain that occurs with the signal listening program translates to an improvement of reading of about 1 1/2 to 2 years. In other words, if I train the child and now I make the child as an accurate listener- a more accurate listener- on the average what you'll see is close to a year's worth of gain in their reading abilities immediately after training. But then if you wait 3 or 4 months in which they're actually reading now with their recovered listening, you see most of a second year gain. So in other words if the kid is in the 5th grade and they're reading at the level of let's say a 3rd grader, most children approach that 5th grade reading level as a consequence of training. They gain those 2 years lost. So these are relatively substantial gains that are seen on the average in these controlled studies.
Ginger Campbell: Wow. So I've read that Fast ForWord™ also seems to help children in autism. How does that work?
Michael Merzenich: Well again, the most common or the most consistent deficit that applies in autism- it's on of the DSMIV criteria for identifying autism- is a language impairment. And in fact, commonly children that have problems that give them the inherited weakness that would result in autism are on a continuum with children that are merely language impaired. In other words, if I have a child that has let's say fragile X syndrome because of genetic impairment, in the child that's more severe they might be identified as autistic but they might have an identical twin that's a little less severe, and that twin will be merely language-impaired, you could say.
Ginger Campbell: Mm.
Michael Merzenich: So autism is on a continuum with language impairment and there's lots of studies that show that autism neurologically is related to language impairment. You could say that something more complicated happens in the brain that results in a whole series of other complex problems for the child that are beyond merely struggling to interpret language...
Ginger Campbell: Mm hm.
Michael Merzenich: and the things that come from that. I don't want to dismiss language impairment as being important, but I think you have to understand what I'm saying. In any event, if the child has a language age of about 4 or greater, Fast ForWord has demonstrated to be very useful for most children. If the child's language development is more primitive, then it has no measured benefit for language per se.
Ginger Campbell: Mm hm.
Michael Merzenich: I did a controlled study- not a controlled study- I did a study in which I just looked longitudinally. historically when Fast ForWord™ was first developed, at a series of I think 17 autistic children. Not completely sure of the number but it was of that order. About half the children were autistic, about half of them were pervasively developmentally disorder with language impairment- so-called PDDNOS (not otherwise specified). And to make a long story short, I saw language gains on a language battery that averaged about 1 1/2 standard deviations. So big effects. But those were selected children that all had some level of language ability when they started.
Ginger Campbell: Mm hm.
Michael Merzenich: They were probably also selected by the therapist that trained them as being likely to benefit, but I would say probably about 25,000 or 30,000 maybe 35,000 children have been trained who are autistic with Fast ForWord™ now. I have people come up to me all the time and tell me that it saved their autistic child's bacon. And whenever it's been looked at at all in a controlled way or in these longitudinal studies it's been demonstrated to be beneficial in most children- not all but in most children, but most beneficial in children that are above a certain language age.
Ginger Campbell: Did you redesign Fast ForWord™ to be more helpful to autistic children or do they still do the original version?
Michael Merzenich: Well the original version has gone through a series of iterations so it's better and better and better and easier and easier to get started and also Scientific Learning created programs that were designed to help the children to some extent before they initiated Fast ForWord™. But it hasn't been redesigned as much as it should be, and actually it's on my agenda as something that we have to do in the very near future. I'm just done working on an agreement with Scientific Learning to get permission from them to allow me to do that.
Ginger Campbell: Alright, because you're not directly part of that company.
Michael Merzenich: Well, I'm an advisor to them on their research programs, and I communicate with them regularly and try to help them regularly.
Ginger Campbell: Right. Well I really appreciate you taking the time to talk to me today, Dr. Merzenich. Is there anything else you'd like to share with my listeners before we close?
Michael Merzenich: Take your brain fitness seriously because it's all up to you, and remember that you have this great asset that you carry around within your skull- to be stronger, to be better. It's more or less up to you if you utilize it or if you allow yourself to deteriorate in ways that just aren't necessary or completely necessary. And keep up the good fight.
Ginger Campbell: Thank you.
Michael Merzenich: I enjoyed talking to you, Ginger.
Ginger Campbell: I did too. Thanks so much.
Michael Merzenich: You bet.
Ginger Campbell: Bye.
Michael Merzenich: Bye.
The Brain Science Podcast is copyright 2009, Virginia Campbell, MD. You can copy this podcast to share it with others, but for any other uses or derivatives, please contact me at pdocartemis@gmail.com.
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