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alpha waves

Kevin Spencer kspencer at s.psych.uiuc.edu
Wed May 7 02:17:56 EST 1997


sblack at UBISHOPS.CA (Stephen Black) writes:

>Since I haven't gotten flamed yet, I guess my first attempt at 
>posting this didn't make it. Here it is again:

I was waiting for some juicy flames on this thread but nothing has
happened so far.  Darn.

>Well, I'm probably wasting my time speaking to the converted on this
>one, but the alpha wave stuff is a crock. Barry Beyerstein (references
>below) says "Alpha brain-waves are marketed as a way to produce
>relaxation, healing and meditative or occult states. In fact, they are
>related to activity in the visual system and have no proven curative or
>paranormal powers" (Beyerstein, 1985). 

Hmmm, while he's right that alpha waves have nothing to do with healing
or occult states, and have no special powers, I would disagree with that
statement on a couple of points.  First, alpha activity is typically
enhanced when a person is "resting", that is, not engaged in a mentally-
demanding task but is asleep.  So I would say that enhanced alpha activity
is associated with relaxation.  It's one of the easiest EEG phenomena to
observe.

Furthermore, there is a lot of "real" scientific literature in which
the reduction of alpha activity (called "desynchronization") is related
to "activation" of the cortex.  The idea is that alpha-band activity
reflects a "resting state" of the cortex, and when a piece of cortex
becomes engaged in information processing or activated, the EEG becomes
less synchronized.  Alpha activity decreases, and higher-frequency
activity increases.

(As an aside, alpha desynchronization has not been proven to really
measure cortical activation.  What is cortical activation anyway?  I
would like to see studies comparing EEG and PET/fMRI measures of
cortical activation to see whether they come up with the same results.
But whatever alpha desynchronization is related to, consistent effects
are found, so it's not a totally flaky idea.)

As for alpha waves being related to the visual system, well, visual
cortex does generate the most alpha activity, especially when the eyes
are closed (the "resting state" hypothesis).  However, alpha waves
are certainly observed over other areas of cortex.  Maybe the large
amount of alpha activity in visual cortex is related to the higher
density of cells there (or is it just area 17?).

Kevin
-----------------------------------------------------------
Kevin Spencer
Cognitive Psychophysiology Laboratory and Beckman Institute
University of Illinois at Urbana-Champaign
kspencer at s.psych.uiuc.edu
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