Michael Merzenich – Exploring the re-wiring of the brain part1


This machine that we all have residing in our skulls reminds me of an aphorism of a common Woody Allen that asked about whats the very best thing to have within your skull. And its this machine. And its constructed for change. Its all about change. It confirm on us stability to do things tomorrow that we cannt do today. Things today that we couldn’t do yesterday. And of course its born stubid.

The last time we are in the presence of a baby, this happens to be my granddaughter Metra; isn’t she fabulous. Non the less, when she poped out. Despite the fact that her brain had actually been progressing in its development for several months before – on the basis of the experience in the wome. She had very little abilities, as does every infant at the point of normal natural full term birth. Her perceptual abilities where to be crude. There is no indication that there is any thinking going on, in fact there is little evidence that there is any cognitive ability in a very young infant. Infant dont respond to much. There is not really much of an indication in fact that there is a person on board. Infants can only in a very primitive and limited way controll her movements.

It will be several months before that infant can do something as simple as reshaping grasp under co-voluntary object can retrieve it. Usually to the mouth. And there will be some month before-ward when we see a long study progression of the evolution from the first wiggles to rolling over sitting up and crawling, standing, and walking. Before we get to that magical point in which we can rotate in the world. And yet if we look forward in the brain we see pretty remarkable advance. By this age the brain can actually store, can fastly retrieve the meanings of thousands, tens of thousands of objects, actions and their relationships in the world. And those relationships can in fact be constructed in hundreds of thousands potentially millions of ways. At this age, the brain controls very refined perceptual abilities. It actually has a growing repertoire of cognitive skills. This brain is very much a thinking machine. And at this stage there is absolutely no question that this brain has a person on board.

And in fact at this age it is substantially controlling its own self-development. And by this age we see a remarkable evolution in his capacity to control movement. Now movement is advanced to the point where it can actually control a set of movement simultaneously. In a complex sequence in complex ways as would be required of playing in a complicated game like soccer. This boy can dance a soccer ball on his head. He comes from São Paulo Brazil, about forty per cent of boys have this ability. You can go out in this community and you have difficulty finding a boy that has this ability. And if he did, he probably be from Sau Paulo. And that is another way of saying that our individual skills and abilities are very much shaped by our environments.

And as an environment extends into our contemporary culture – the thing our brains is challenged with – because what we have done in our personal evolutions is build up a large repertoire of specific skills and abilities. They are specific to our own individual histories and in fact they result in a wonderful differentiation in human kind. In a way that in fact, no two of us are quiet alike. Every one of us has a different set of acquired skills and abilities. And all drive out of the plasticity, the adaptability of this really remarkable adaptive machine.

In an adult brain of course we build up a large repertoire of master skills and abilities that we can perform more or less automatically from memory. And that define us as acting moving, thinking creatures. And we study this as the nerdy, laboratory university scientist we are. Engaging the brains of animals like rats, or monkeys or this peculiar creatures – one of the more bizarre forms of life on earth – to engage them in learning new skills and abilities. And we try to track the changes that occure as a new skill or ability is aquired. And in fact we do this in individuals of any age in this different species, that is to say from infancy and adulthood to old age.

And so we might engage a rat f.e. to aquire a new skill or ability that might involve the rat using its claw to master a particular manual taks behaviour. Just like we might examine a child in its ability to aquire the sub-skills or the general overall skill of accomplishing something like mastering the ability to read. We might look in an older individual who has mastered a complex set of abilities that might relate to read musical notation or performing the mechanical act of performance that apply to musical performance. From these studies, we define two great epos of the plastic history of the brain.

The first commonly called the “critical periode”; And thats the period in which the brain is setting up in its initial form its basic processing machinery. This is actually a periode of dramatic change, in which it doesn’t take learning per se to drive the initial differentiation of the machinery of the brain. All it takes for example in the sound domain is exposure to sound. And the brain actually is at the mercy of the sound environment in which it is reared. So. f.e. I can hear an animal in an environment in which there is meaningless dump sound. A repertoire of sound that I make up. But I make just by exposure artificially important to the animal and its young brain. And what I see is that the animal brain sets up its initial processing of that sound in a formless idealized, within the limits of its processing achievements, to represent it in an organized and orderly way.

The sound does not have to be valuable to the animal. I can raise the animal in something that could be hypothetical valuable, like the sounds that simulates the sounds of a native language of the child, and I see the brain actualy develop a processor that is specialized for the complex array or repertoire of sounds. It actually exaggerates their separateness of representation in multi dimensional neurological representational terms. Or I can expose the animal to a completely meaningless and destructive sound. I can raise the animal under conditions that would be equivalent to raising a baby under a moderately loud sealing fan in the presents of continous noise. And when I do that, actually specialize the brain to be a master processor for that meaningless sound. And I frustrate its ability to represent any meaningful sound as a consequence.

Such things in the early history of babies occure in real babies. And they account for the beautiful evolution of a language specific processor in every normally developing baby. And so do they also account for development of defective processing in a substantial population of children. They are more limited, as a consequence, in their language ability for an older age.

Now, in this early periode of plasticity, the brain actually changes outside of a learning context. I don’t have to pay attention to what I hear. The input does not have to be meaningful. I dont have to be in a behavioral context. And this is required so that the brain sets up its processing, so that it can act differentially, so that it can act selectively so that the creature that wears it, that carries it, can begin to operate on it in a selective way.

In the next epoch of live which applies for most of life, the brain is actually refining its machinery as it masters a wide repertoire of skills and abilities. And in this epoch, which extends from late in the first year of life to death, its doing this under behavioral control. And another way of saying that the brain has strategies to define the significance of the input to the brain. And its focusing on skill after skill or ability after ability under a specific attentional control. And its a function weather the goal or behaviour is achieved or wether the brain or this individual is rewarded by the behaviour. This is actually very powerful expressed in that its the basis of a real differentation of one individual from another.

You can look down in a brain of an animal that is engaged a specific skill and you can wittness and document this change on a variety of levels. So here is a very simple experiments that was actually conducted 5 years ago. The simple experiment where a monkey had been trained in a task manipulating a tool that is equivalent in difficulty to a child learning to manipulate or handle a spoon. And the monkey actually masters the test in 700 trials. In the beginning the monkey could not perform this task at all and had a success rate of about one in eight trials. And those trials where elaborate, each attempt substantially different from another, and the monkey gradually developed a strategy. And 700 or so trials later the monkeys’ performing it flawlessly. Never fails, his successful and its retrieval of food with this tool every time.

At this point the taks has been performed in a beautiful stereotyped way, very beautifully regulated and highly repeated trial to trial. We can look down on the brain of the monkey and we see that its distorted. We can track this changes and have tracked this changes in behaviors across time. And here we see the distortion reflected in the map of the skin surfaces of the hand of the monkey. This is a map down in the surface of the brain in which the very elaborated experiment we reconstructed shows the responses -location by location- in an highly detailed response mapping other responses of its neurons. And we see here a reconstruction of how the hand is represented in the brain. We actually distorted the map by the exercise and that is indicated in the pink. There are couple of fingertips surfaces that are larger and these are surfaces the monkey is using to manipulate the tool.

We look at the selectivity of responses in the cortex of the monkey we see that the monkey has actually changed the filter characteristics which represents inputs form the skin of the fingertips that are engaged. In other words, there is still a single simple representation of the fingertips in this most organized of critical areas of the surface of the skin of the body. And yet knowledge represented in substantially finer grain. The Monkeys getting more detailed information from the surfaces.

Actually we have looked in several different critical areas in the monkeys learning’s task. Each changes in ways that are specific to the skill or ability. So f.e we can look to the critical area that represents input thats controlling the posture of the monkey, we look in critical areas that control specific movements and the sequences of movements in the behaviour and so for. There are all remodeled. They all become specialized for the task of the hand. There are fifteen or twenty critical areas that are change specifically when you learn a simple skill like this.

And that represents in your brain really a massive change. It represents the change in a reliable way of the responses of tens of millions possible hundreds of millions of neurons in your brain. It represents changes in hundreds of millions possibly billions synaptic connections in your brain. This is constructed by physical change, and the level of the construction that occure is massive. Think of the changes that occure in the brain of a child in the course of acquiring the movement behaviour abilities in general or acquiring the native language abilities. The changes are massive.

What its all about is the selective representation of things that are important to the brain. Because in most of the life of the brain this is under control of behavioral context. Its what you pay attention too. Its what you worthing to you, its what your brain regards itself as positive and important to you. Its all about critical processing and full brain specialization and that underlies your specialization. That is why you, and your many skills and abilities, are unique specialist. A specialist that is vastly different in your physical brain in detail from the brain of an individual a hundred years ago. Enormously different in the details from the brain of the average individual a thousand years ago.

Now, one of the characteristics of this change process is that information is always related to other imputs or information thats occuring in immediate time and context. And thats because the brain is constructing representation of things that are correlated in little moments of time. And they relate to one another in little moments of successive time. The brain is recording all information and driving all change in temporal context.

Overwhelmingly the most powerful context thats occured in your brain is you. Millions of event have occured in your history that are related in time to yourself as the reciever or yourself as the actor, yourself as the thinker, yourself as the mover. Millions of times little pieces of sensations come in from the surface of your body that are always associated with you as the reciever and that result in the embodiment of you. You are constructed, your self is constructed from this billions of events, thats constructed, thats created in your brain by physical change. This is the marvelously constructed brain that results in an individual form. Because each one of us has vastly different histories and vastly different experiences that driving us, this marvelous differentiation of self, of personhood.

We used this research to try to understand not just how a normal person develops and elaborates his skills and abilities, but also try to understand the origins of impairment and the origins of differentness or variations that might limit the capacities of a child or an adult. And then I talk about using this strategies to actually design brain clusters based approach to drive correction in the machinery of the child that increases the competence of the child as a language reciever and user and thereafter as a reader.

And I rather talk about experiments that involve actually using this brain science first of all to understand how it contributes to the loose of function as we age. And by using that in a targeted approach, where we try to differentiate the machinery to recover function in old age.

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