Plasticity and the Brain: Merzenich and Taub

Michael Merzenich blogs at On the Brain, where he never seems to mince words as he gets right down to the subject at hand. PositScience: The Science with Dr. Merzenich is a 9 minute video during which Merzenich talks about the development of the brain, brain change, and plasticity.

His current company, PositScience, is focused on how to maintain plasticity and encourage brain change and growth for aging adults, with the goal of improving memory. If you are interested, there are a number of YouTube videos about this, including interviews with neuroscientists and users of the PositScience program.

[October 11, 2008 update – in going through my files I found a May, 6, 2007 NY Times article about Merezenich and his company, entitled Muscular Metaphor, which provides background on the company.]

Merezenich is another one of the neuroscientists featured in Norman Doidge’s book, The Brain That Changes Itself, and may best be known for his work on developing the cochlear implant.

What interests me most, though, are the findings of his research.

‘You cannot have plasticity in isolation … it’s an absolute impossibility.’ His experiments have shown that if one brain system changes, those systems connected to it change as well. The same ‘plastic rules’ – use it or lose it, or neurons that fire together wire together – apply throughout. Different areas of the brain wouldn’t be able to function together if that weren’t the case.

Within the same chapter, Doidge explains the brain chemistry that takes place during learning and unlearning, both of which take place as a function of plasticity. As you learn something, the neurons involved in the learning fire together and thus wire together. This is facilitated in cells by LTP (long-term potentiation), which is the chemical process of strengthening the synaptic connections. When the brain is poised for unlearning, the opposite takes place due to LTD (long-term depression), where the synaptic connections are weakened and disconnected.

Another neuroscientist who brightens the pages of Doidge’s book is Edward Taub. His research and innovation in stroke treatment pioneered CI (constraint induced) therapy, which exploits the brain’s plasticity. You can listen to Taub explain his work in an interview on The Brain Science Podcast, where there are also a number of links and references posted.

Taub’s research supported Merzenich’s findings that “when a brain map is not used, the brain can reorganize itself so that another mental function takes over that processing space.” In addition, with specific application to stroke patients and anyone who had some form of brain damage, “Not only could the brain respond to damage by having single neurons grow new branches within their own small sectors, but, the experiment showed, reorganization could occur across very large sectors.”

Hazaah!