Tag Archives: hearing

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!

Hearing does not equal Listening

In the July 8, 2007 New York Times Book Review, Haruki Murakami writes in his essay, Jazz Messenger,

Practically everything I know about writing, then, I learned from music. … Even now, almost 30 years later, I continue to learn a great deal about writing from good music.

Murakami goes on to quote Thelonious Monk who, when discussing how he gets special sounds out of the piano, said

When you look at the keyboard, all the notes are there already. But if you mean a note enough, it will sound different. You got to pick the notes you really mean!

The essay fueled my thinking about how we listen and how we process what we hear. Listening is not always a simple activity. To be sure, if your hearing functions properly, it is easier to hear than to listen, for listening requires attentiveness, and attentiveness usually requires a level of interest or need. Hearing is a physical act; listening is a cognitive one.

Turns out there is even an International Listening Association created “to promote the study, development, and teaching of effective listening in all settings.” And it may come as no surprise that in some schools students are taught how to listen. The University of Minnesota Duluth has a page on Listening Skills, and Study Guides and Strategies provides an interactive guide to Active Listening.

My favorite site about sound, though, is Listen: Making Sense of Sound, part of the Exploratorium online. If you aren’t familiar with it, the Exploratorium is “the museum of science, art and human perception” located in San Francisco, California. Their online exhibit contains a slew of well-prepared, informative yet entertaining interactive activities designed to get you thinking about the act of listening – not just to other people but also to your environment, which contains wondrous sounds of its own.

Listen with your Eyes

Listen with your eyes closed, because what you see influences what you hear.

Thus exhorted Wouter Snoei, a composer from The 192 loudspeaker experience, a concert we attended in Amsterdam with our friends.

speakers.png

Peter Elsea, for the University of California at Santa Cruz electronic music studios, wrote an essay on Hearing and Perception. Although he posted the essay in 1996 (so there may be more current research available), I found it an interesting accompaniment to the 192 loudspeaker concert.

Returning to Wouter’s exhortation, I wear glasses, and wearing glasses impacts my ability to hear. In loud environments particularly, I need to see the speaker’s face and lips to influence the odds of properly hearing what is being said. More on this idea is available in The University of Kent’s peer-reviewed electronic academic journal article posited by Michael A. Forrester, Auditory Perception and Sound As Event: Theorising Sound Imagery in Psychology. If you don’t feel like reading the entire article, skip ahead to section 5.

I suspect if we had kept our eyes open during the loudspeaker experience, we would surely have processed the sounds as coming from the 192 speakers. By listening with my eyes closed, I heard the sounds but conjured up images of the places or people from where the sounds may have emanated. (And yes, I did keep them closed during each of the four pieces!) This is not unlike listening to a radio, as discussed in Forrester’s article. In many instances, listening while seeing combine to enhance the ability to process the sound.

At the HyperPhysics site, hosted by the Georgia State University Department of Physics and Astronomy, you can learn more about the physics of the ear and hearing. And you can get an earful of information at Neuroscience for Kids, including experiments to test your hearing.