December 5, 2005 | David F. Coppedge

How You Tune In

Studies on rats have shown there are certain neurons that respond to changes in the background sound (see LiveScience story on MSNBC News).  We humans probably have these, too.  Rather than firing continuously, they search for changes in the auditory landscape that might be of interest: changes in pitch, loudness or duration in single sounds or patterns of sounds.  The work was done by Ellen Covey and a team at the University of Washington and published in the European Journal of Neuroscience.  “The novelty detector neurons seem to act as gatekeepers, Covey and her colleagues conclude, preventing information about unimportant sounds from reaching the brain’s cortex, where higher processing occurs.”  This is how we can ignore unimportant information, even though it may be loud.  It also may play a part in our sense of humor: “Whatever we have just heard allows us to anticipate what will come next, and violations of our predictions are often surprising or humorous.”

One of the great mysteries of neuropsychology and of philosophy is the mind-body problem.  We continue to learn about the intricate machinery, the physical and chemical properties of our neurons, but how do these mechanical activities translate into our sensations of the external world?  How does a chain of processes leading to the brain connect us to what is really out there?  How can we be sure that the end of the chain, what is actually closest to us, corresponds to the source of the signal in the external world?  How can our minds choose to focus in on certain sensations around us?
    Even the act of raising an arm is a complete mystery.  You can command your arm “Up!” and make it go up, or you can even make it disobey your command or stay still.  Such simple things are really baffling when you think about them.  It is clear that a fantastic array of biological instrumentation is involved, but it also appears hopelessly inadequate to reduce our mental operations to the motions of molecules.  Stories like this can be cause for thoughtful reflection.

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Categories: Human Body, Mammals

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