Brainwave Entrainment and Beyond: Toward Holistic Approach

Brainwave Entrainment and Beyond: Toward Holistic

Approach

Prof. Emil JovanovProf. Emil Jovanov

Electrical and Computer Engineering DepartmentElectrical and Computer Engineering DepartmentThe University of Alabama in HuntsvilleThe University of Alabama in Huntsville

Huntsville, AlabamaHuntsville, Alabama

http://www.ece.uah.edu/~jovanovhttp://www.ece.uah.edu/[email protected]@ece.uah.edu

Brainwave Entrainment Symposium, Stanford, May 2006

Brainwave Entrainment

Goal?Goal? Subject in a loopSubject in a loop

Open loop vs. Closed loop Open loop vs. Closed loop Driving vs. Biofeedback Driving vs. Biofeedback Exact frequency, current state of the userExact frequency, current state of the user

Range of EEG frequencies below audible Range of EEG frequencies below audible frequency rangefrequency range Rhythmic stimulationRhythmic stimulation Binaural beat stimulationBinaural beat stimulation

Multimodal stimulation and biofeedbackMultimodal stimulation and biofeedback AuditoryAuditory Photic drivingPhotic driving VibrationVibration


Functional brain

EElectrical activity recording techniqueslectrical activity recording techniques EEGEEG ( (EElectrolectroEEncephaloncephaloGGraphy)raphy) ERPERP ( (EEvent vent RRelated elated PPotentials)otentials) ECoGECoG ( (EElectrolectroCCorticoorticoGGraphy)raphy) MEG MEG ((MMagnetoagnetoEEncephaloncephaloGGraphy)raphy)

fMRIfMRI ((ffunctional unctional MMagnetic agnetic RResonanceesonance PET, PET, SPECT SPECT ((PPositron or ositron or SSingle ingle PPhoton hoton

EEmission mission TTomography)omography) IIRR ImagingImaging MRIMRI Spectroscopy Spectroscopy


Spectral analysis

absolute powerabsolute power (the amount of energy within (the amount of energy within a particular frequency band)a particular frequency band)

relative powerrelative power (proportional contribution of (proportional contribution of certain frequency band in the total power certain frequency band in the total power spectrum) spectrum)

mean/peak frequencymean/peak frequency inter/intrahemispheric differencesinter/intrahemispheric differences coherencecoherence (measure of synchronicity between (measure of synchronicity between

two electrode sites)two electrode sites)


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 < 1Hz -

Hypothetical representation

Individual neurons

Specialized regions

Physical consciousness

Mental consciousness

Higher level of consciousness

Collective consciousness

EEG Correlates of Conscious States

BehavioralContinuum

EEGCharacteristics

State ofAwareness

Efficiency

Strong, exci-ted emotion;fear, rage,anxiety

Desynchronized: lowto moderateamplitude; fastmixed frequencies

Restricted awareness;divided attention;diffuse, hazy;"confusion"

Poor: lack ofcontrol, freezingup, disorganized

Alertattentiveness

Partially synchro-nized: mainly fastlow-amplitude waves

Selective attention,but may vary or shift;"concentration"anticipation; "set"

Good: efficient,selective, quickreactions; orga-nized for serialresponses

Relaxedwakefulness

Synchronized:optimal alpha rhythm

Attention wanders –not forced; favors freeassociation

Good: routinereactions andcreative thought

EEG Correlates of Conscious States (II)

BehavioralContinuum

EEGCharacteristics

State ofAwareness

Efficiency

Drowsiness Reduced alpha andoccasionallow-amplitudeslow waves

Borderline partialawareness; imageryand reverie; dreamlikestates

Poor:uncoordinated,sporadic, lackingsequential timing

Light sleep Spindle bursts andslow waves (larger);loss of alphas

Markedly reducedconsciousness (loss ofconsciousness); dreamstate

Absent

Deep sleep Large and very slowwaves (synchronybut on slow timebases); randomirregular patterns

Complete loss ofawareness (nomemory of stimulationor dreams)

Absent

Coma Isoelectric toirregular large slowwaves

Complete loss ofconsciousness; little orno response tostimulation; amnesia

Absent


Correlates of Altered States of Consciousness

Establishing Establishing alpha activityalpha activity during epochs with during epochs with opened eyes (Hirai60)opened eyes (Hirai60)

Increased Increased amplitude of alpha activityamplitude of alpha activity (Hirai60, (Hirai60, Banquet72, Wallace72)Banquet72, Wallace72)

Slower frequencySlower frequency of alpha rhythm (Hirai60 , of alpha rhythm (Hirai60 , Banquet72, Wallace72)Banquet72, Wallace72)

Rhythmical theta wavesRhythmical theta waves (Hirai60, Banquet72, (Hirai60, Banquet72, Wallace72)Wallace72)

Increased synchronization Increased synchronization ((hypersynchronizationhypersynchronization Banquet72) Banquet72)

Dissociation of perceptionDissociation of perception from the external from the external sense organs (Hirai60, Ray88)sense organs (Hirai60, Ray88)


Correlates of Altered States of Consciousness (II)

Occasional Occasional fast wave activityfast wave activity (Banquet73, (Banquet73, Ray88)Ray88)

Synchronous Theta BurstsSynchronous Theta Bursts (Hebert77). (Hebert77). Increased Increased intrahemispheric coherenceintrahemispheric coherence in the in the

alpha and theta frequency bands (Farrow82).alpha and theta frequency bands (Farrow82). Autonomous nervous system changesAutonomous nervous system changes Transcendent signalTranscendent signal (Ray94) (Ray94)


Fundamental problems

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

Subjective time-frame (transcendence?)

t’ = (t)

t

t’

Mind

Measurementequipment

non linear function


Signal Processing Requirements

Most processing algorithms require Most processing algorithms require large number of sampleslarge number of samples FFT of 1024 points @ 256 Hz FFT of 1024 points @ 256 Hz 4 seconds 4 seconds Time-frequency tradeoffTime-frequency tradeoff

Wavelet analysisWavelet analysis

Short events are lost Short events are lost


EEG visualization methods


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


Sonification - disadvantages

Difficult perception of precise quantities Difficult perception of precise quantities and absolute values. and absolute values.

Limited spatial distributionLimited spatial distribution Some sound parameters are not Some sound parameters are not

independent (pitch depends on loudness) independent (pitch depends on loudness) Interference with other sound sourcesInterference with other sound sources Absence of persistenceAbsence of persistence Dependent on individual user perceptionDependent on individual user perception


Sonification - approaches

RhythmRhythm PitchPitch subjective perception of frequency subjective perception of frequency TimbreTimbre characteristic of instrument characteristic of instrument

generating sounds generating sounds Loudness Loudness (volume) (volume) Location Location of sound sourceof sound source

balancebalance of stereo sound of stereo sound


Rhythm

Very powerful methodVery powerful method Natural use of very low frequenciesNatural use of very low frequencies

Delta and Theta frequenciesDelta and Theta frequencies Complex patterns is sub-Delta bandComplex patterns is sub-Delta band


Binaural Entrainment

Excellent solution for Excellent solution for low frequencies low frequencies Brainwave frequenciesBrainwave frequencies

Superposition of two Superposition of two audio channels with audio channels with small difference in small difference in basic frequencybasic frequency L: 1000 HzL: 1000 Hz R: 1007 HzR: 1007 Hz Generated: Generated:

1007-1000=7Hz1007-1000=7Hz Fine control of the Fine control of the

entrained frequencyentrained frequency


Holistic Approach

Mental processes Mental processes (EEG)(EEG)

BreathingBreathing Heart rateHeart rate

Cardiovascular Cardiovascular systemsystem

Glands & HormonsGlands & Hormons Body functionsBody functions


Example #1: Yogic breathing (1 b/min)

250 300 350 400 450 500 550 600600

700

800

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1000

1100

1200

Before

400 500 600 700 800 900600

700

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1000

1100

1200

During

1000 1050 1100 1150 1200 1250 1300 1350600

700

800

900

1000

1100

1200

After

LF/HF=146


Example #2: Chanting

250 300 350 400 450 500 55050

55

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95

2700 2720 2740 2760 2780 2800 2820 2840 2860 2880 290050

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The Awakened Mind (C. Maxwell Cade) The importance of different frequency The importance of different frequency

bandsbands Holistic approachHolistic approach

L RL R

Frequency


Conclusions

Subtle processes require sophisticated Subtle processes require sophisticated processing and presentationprocessing and presentation Flexible software supportFlexible software support

System customizationSystem customization Biofeedback Biofeedback

Multimodal stimulation Multimodal stimulation very effective very effective Improves immersionImproves immersion Issue: customization and maximizing Issue: customization and maximizing

perceptual distance perceptual distance Goal: becoming ONEGoal: becoming ONE

Brainwave Entrainment and Beyond: Toward Holistic Approach

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