Brainwave synchronization

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Brainwave synchronization, commonly referred to as "brainwave entrainment," is the practice of entraining one's brainwaves to a desired frequency, by means of a periodic stimulus with corresponding frequency. The stimulus can be aural as in the case of binaural beats, monaural beats, and isochronic tones, visual, as with a dreamachine, a combination of the two with a mind machine, or even electromagnetic radiation.

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[edit] Overview

Brainwave entrainment, also known as "brainwave synchronization", is concerned with frequency following response, a naturally occurring phenomenon where the human brain has a tendency to change its dominant EEG frequency towards the frequency of the dominant external stimuli applied to it.

Lower level brain frequency, associated with deep sleep and meditation are not audible to humans, so an acoustic tone is generated using a technique called binaural beats. Another method is to produce tones that pulse at the desired frequencies. This is known by musicians as tremolo.

Brainwave entrainment has many historical, and often social, manifestations. Drum circles, chanting, and staring at a fire were all ways that our ancestors partook in the phenomenon.

Brainwave synchronization with binaural beats is said to help 'synchronize the two hemispheres of the brain', hence the Hemi-Sync (by Monroe Institute) example product. There is, as with most quasi-scientific theories,[Neutrality disputed — See talk page] some dispute over the actual truth in these claims.

It is also a private case of functional brain connectivity concept, whereas functional connectivity is defined as the temporal correlation between spatially-remote neurophysiological events, expressed as deviation from statistical independence (temporal correlation) across these events in distributed neuronal groups and areas, which produce the brainwaves.[1]

[edit] Binaural beats

Main article: Binaural beats

Binaural beats deserve special mention because of the intriguing manner in which the desired frequencies are obtained. Brainwave synchronization (entrainment) may be achieved when audio signals are introduced to the brain causing a response directly related to the frequency of the signal introduced, called binaural beats. Two tones close in frequency generate a beat frequency at the difference of the frequencies, which is generally subsonic. For example, a 500 Hz tone and 510 Hz tone will produce a subsonic 10 Hz tone, roughly in the middle of the alpha range. The resulting subsonic tone may affect the state of mind of the subject. The "carrier frequency" (e.g., the 500 Hz in the example above), is also said by some to affect the quality of the transformative experience.[citation needed] Note that this effect is achieved without either ear hearing the pulse when headphones are used. Instead, the brain produces the pulse by combining the two tones. Each ear hears only a steady tone. Although some have claimed that these frequencies do provide help in treating certain medical conditions,[2] there is not a wide acceptance by the medical community to adopt the practice of brainwave synchronization for emotional/mental disorders. The fixed, constant frequency of the synchronization is less helpful than techniques such as classical neurofeedback or learning meditation, also which naturally generate brain wave frequencies that differ from person to person and may vary from minute to minute.[citation needed]

[edit] See Also

[edit] Notes

  1. ^ for the recent review see Fingelkurts An.A., Fingelkurts Al.A., Kähkönen S. Functional connectivity in the brain – is it an elusive concept? Neuroscience & Biobehavioral Reviews. 2005, 28(8):827-836). As the authors have stated, "the functional brain connectivity has become one of the most influential concepts in modern cognitive neuroscience, especially given the current shift in emphasis from studies of functional segregation to studies of functional integration."
  2. ^ The Clinical Guide to Light and Sound, Thomas Budzynski, Ph.D.

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