Entrainment of brainwaves

[G K GRAY]

In article <4l3g00$el4 at vixen.cso.uiuc.edu>, Kevin Spencer (kspencer at s.psych.uiuc.edu) writes:
>Emery Carr <ecarr at infohwy.com> writes:
>
>>I don't know if this is the right newsgroup... so steer me in the right 
>>direction if you can...
>
>>I'm searching for information about how to use binaural beats to entrain 
>>brainwave frequencies.
>
>Check out the literature on "steady-state evoked responses".  I think
>that's what you're looking for.
>
>>The only info. I have found so far is that 200hz and 210hz will cause a 
>>frequency following response of 4hz in the brain.
>
>Hmm, never heard of that one before.
>
>Kevin
>-----------------------------------------------------------
>Kevin Spencer
>Cognitive Psychophysiology Laboratory and Beckman Institute
>University of Illinois at Urbana-Champaign
>kspencer at p300.cpl.uiuc.edu / kspencer at psych.uiuc.edu
>-----------------------------------------------------------
>
>Reply to: gord at homostudy.win-uk.net

The problem here seems from this corner to be largely the result of
too narrow specialisation in the teaching (and learning!) of
neuroscience. In fact from a wider view it is quite simple when we
consider the "wiring" of auditory circuits - in this case the role
of discrepancy detectors in determining the *source* of a sound.

Note that superficially this might seem to have little or nothing
to do with Emery Carr's question, but it is the cause of the
observed EEG phenomenon.

Consider the wave-forms below:

A: single frequency.

    l____l____l____l____l____l____l____l____l____l____l  L AC

    _l____l____l____l____l____l____l____l____l____l___   R AC

    ll   ll   ll   ll   ll   ll   ll   ll   ll    Discrepancy 
   /  \
   L  R
   
B: two frequencies

    l____l____l____l____l____l____l____l____l____l____l  L AC

    l___l___l___l___l___l___l___l___l___l___l___l___l__  R AC

   nil  ll  l_l_l  ll  nil  ll  l_l_l  ll  nil  ll Discrepancy
   
   AC - Auditory Channel read by EEG

Note: The *beat* frequency appearing on the EEG is that which comes
from the discrepancy detectors

        In the language of computer engineers the discrepancy
detectors correspond to a NAND (Not AND) circuit, lateral inhibition
to NOR (Not OR).

Cheers  Gord