Brainwave Entrainment and Beyond: Toward Holistic Approach

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Brainwave Entrainment and Beyond Toward Holistic
Approach

• Prof. Emil Jovanov
• Electrical and Computer Engineering Department
• The University of Alabama in Huntsville
• Huntsville, Alabama
• http//www.ece.uah.edu/jovanov
• jovanov_at_ece.uah.edu

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Brainwave Entrainment

• Goal?
• Subject in a loop
• Open loop vs. Closed loop
• Driving vs. Biofeedback
• Exact frequency, current state of the user
• Range of EEG frequencies below audible frequency
  range
• Rhythmic stimulation
• Binaural beat stimulation
• Multimodal stimulation and biofeedback
• Auditory
• Photic driving
• Vibration

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Functional brain

• Electrical activity recording techniques
• EEG (ElectroEncephaloGraphy)
• ERP (Event Related Potentials)
• ECoG (ElectroCorticoGraphy)
• MEG (MagnetoEncephaloGraphy)
• fMRI (functional Magnetic Resonance
• PET, SPECT (Positron or Single Photon Emission
  Tomography)
• IR Imaging
• MRI Spectroscopy

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Spectral analysis

• absolute power (the amount of energy within a
  particular frequency band)
• relative power (proportional contribution of
  certain frequency band in the total power
  spectrum)
• mean/peak frequency
• inter/intrahemispheric differences
• coherence (measure of synchronicity between two
  electrode sites)

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Brainwave Frequencies
Frequency band Frequency Physiological role
Gamma ( ? ) 40-60 Hz Individual Neurons
Beta ( ? ) 12-30 Hz Mental Activity
Alpha ( ? ) 8-12 Hz Awake state
Theta ( ? ) 4- 8 Hz REM sleep, meditation
Delta ( ? ) 1-4 Hz Deep sleep
sub - Delta lt 1Hz -
Hypothetical representation
Individual neurons
Specialized regions
Physical consciousness
Mental consciousness
Higher level of consciousness
Collective consciousness
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EEG Correlates of Conscious States
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EEG Correlates of Conscious States (II)
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Correlates of Altered States of Consciousness

• Establishing alpha activity during epochs with
  opened eyes (Hirai60)
• Increased amplitude of alpha activity (Hirai60,
  Banquet72, Wallace72)
• Slower frequency of alpha rhythm (Hirai60 ,
  Banquet72, Wallace72)
• Rhythmical theta waves (Hirai60, Banquet72,
  Wallace72)
• Increased synchronization (hypersynchronization
  Banquet72)
• Dissociation of perception from the external
  sense organs (Hirai60, Ray88)

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Correlates of Altered States of Consciousness (II)

• Occasional fast wave activity (Banquet73, Ray88)
• Synchronous Theta Bursts (Hebert77).
• Increased intrahemispheric coherence in the alpha
  and theta frequency bands (Farrow82).
• Autonomous nervous system changes
• Transcendent signal (Ray94)

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Fundamental problems

• Subjective time-frame (reference)
• Signal processing requirements

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Subjective time-frame (transcendence?)
t
Mind
t F(t)
t
F - non linear function
Measurement equipment
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Signal Processing Requirements

• Most processing algorithms require large number
  of samples
• FFT of 1024 points _at_ 256 Hz ? 4 seconds
• Time-frequency tradeoff
• Wavelet analysis
• Short events are lost

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EEG visualization methods
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Sonification - advantages

• Faster processing than visual presentation
• Easier to focus and localize attention in space
  (appropriate for sound alarms)
• Good temporal resolution
• Additional information channel
• Possibility to present multiple data streams

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Sonification - disadvantages

• Difficult perception of precise quantities and
  absolute values.
• Limited spatial distribution
• Some sound parameters are not independent (pitch
  depends on loudness)
• Interference with other sound sources
• Absence of persistence
• Dependent on individual user perception

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Sonification - approaches

• Rhythm
• Pitch subjective perception of frequency
• Timbre characteristic of instrument generating
  sounds
• Loudness (volume)
• Location of sound source
• balance of stereo sound

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Rhythm

• Very powerful method
• Natural use of very low frequencies
• Delta and Theta frequencies
• Complex patterns is sub-Delta band

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Binaural Entrainment

• Excellent solution for low frequencies
• Brainwave frequencies
• Superposition of two audio channels with small
  difference in basic frequency
• L 1000 Hz
• R 1007 Hz
• Generated 1007-10007Hz
• Fine control of the entrained frequency

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Holistic Approach

• Mental processes (EEG)
• Breathing
• Heart rate
• Cardiovascular system
• Glands Hormons
• Body functions

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Example 1 Yogic breathing (1 b/min)
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Example 2 Chanting
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The Awakened Mind (C. Maxwell Cade)

• The importance of different frequency bands
• Holistic approach

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Conclusions

• Subtle processes require sophisticated processing
  and presentation
• Flexible software support
• System customization
• Biofeedback
• Multimodal stimulation
• very effective
• Improves immersion
• Issue customization and maximizing perceptual
  distance
• Goal becoming ONE