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!

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7 thoughts on “Plasticity and the Brain: Merzenich and Taub

  1. Pingback: The Magic of Your Brain: 3 Principles of Transformational Neuroplasticity. - Julian Walker Yoga

  2. Pingback: New Year and Brain Fitness « Neurons Firing

  3. synapsesensations Post author

    Hi Wendy,

    Here is a follow-up to your comment and my reply. I am reading John Medina’s “Brain Rules”, and on page 134, in the chapter on long-term memory, he describes LTP.

    Norman Doidge, on page 117 of “The Brain that Changes Itself”, writes:

    Different chemistries are involved in learning than in unlearning. When we learn something new, neurons fire together and wire together, and a chemical process occurs at the neuronal level called “long-term potentiation,” or LTP, which strengthens the connections between the neurons. When the brain unlearns associations and disconnects neurons, another chemical process occurs, called “long-term depression,” or LTD (which has nothing to do with a depressed mood state). Unlearning and weakening connections between neurons is just as plastic a process, and just as important, as learning and strengthening them.

    That’s a long quote (at least as it fits in this comment!) but I think it supports LTP and LTD as actual physical processes, as opposed to models. Again, if you have further information to clarify your comment, please share it and keep the conversation going.

    Cheers,
    Laurie

  4. synapsesensations Post author

    Hi Wendy,

    Thank you for your comment. My understanding is that LTP is something that actually happens in the brain, as opposed to being only a model. If you have information that can further clarify your point, please send it along.

    Thanks!

    Regards,
    Laurie

  5. wendy comeau

    I worry when a neuroscientist uses the terms LTP and LTD as if they are known mechanisms of plasticity in vivo. Rather, these two terms refer to an extensively studied MODEL of plasticity. There is an important distinction here that needs to be clarified so as not to mislead the public.

  6. synapsesensations Post author

    Quick Note: Docartemis initially posted another comment but the links did not take. We emailed back and forth, and here is a revised comment, which I am posting on her behalf. (I deleted the initial comment.)

    Thanks again for mentioning the Brain Science Podcast at http://brainsciencepodcast.com.

    The main link I was trying to post was for Steven Novella’s interview on Books and Ideas (my other podcast).

    http://booksandideas.wordpress.com/2008/01/18/books-and-ideas-16-interview-with-dr-stephen-novella-from-the-s/

    Novella is a neurologist at Yale, but he is probably better known for his popular podcast, the Skeptics’ Guide to the Universe.

    There is lots of brain-oriented content in the interview, so I thought you would enjoy it.

    Thanks again for your support.

  7. Matt

    This is a great information and linking. What this company, Posit Science, is doing is fantastic. Its amazing actually. Seems like they are really helping a lot of people.

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