Kolb – brain plasticity

Brain plasticity is a word that was begun to be used in the 80s and has become a lot of things to a lot of different people. Basically it’s the idea that you can mold the brain, that you can do this at various levels. So one level is behavioral. So if I learn something there’s some plasticity. But what’s the mechanism? Well I can look at it in terms of how the brain’s organized and I can do that at lots of levels. I can measure electrical activity; I can measure genetic activity and so on. So brain plasticity refers to the idea that the brain is changeable but refers to it in a whole bunch of levels and we have to be careful when we talk about it, what level we’re implying.  

So during development the brain undergoes a sequence of developmental events. So you make cells, the cells migrate to the location that they need to be; the cells begin to differentiate; turn into a visual neuron or a motor neuron or whatever kind of neuron it is. The cells then form connections with other cells. In order to expedite this process so that it works smoothly, all sorts of growth factors are present in the milieu, the extracellular milieu. In development there’s a lot of them there. And they’re needed because you’re making kazillions of synapses. Later in life, you’re making modifications to the existing blueprint, if you like, that you made during development and then discarded a lot of. And so those growth factors aren’t there any longer. Only certain ones are there.  

And so what happens is it’s more difficult to add the synapses later on. And that’s a good thing because you don’t want to go changing the brain all around and forget your mom’s name. You want to keep these things in there. So the brain has to be less plastic, if you like, as it develops so that it keeps all the stuff that’s in there that presumably is important. One way to enhance the plasticity later in life is to put in some of those factors that were in there early. So if, for example, you have a case of dementia or a case of somebody with a brain injury or something, you want to enhance that plasticity and bring back some of those factors. But remember that there’s a risk here of erasing stuff that was put down earlier. So you have to be really careful about it. But that’s why there’s a difference between early and late plasticity.