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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@ece.uah.edu. Brainwave Entrainment. Goal? Subject in a loop
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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@ece.uah.edu
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 Brainwave Entrainment Symposium, Stanford, May 2006
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) • IRImaging • MRI Spectroscopy Brainwave Entrainment Symposium, Stanford, May 2006
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) Brainwave Entrainment Symposium, Stanford, May 2006
Brainwave Frequencies Brainwave Entrainment Symposium, Stanford, May 2006
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) Brainwave Entrainment Symposium, Stanford, May 2006
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) Brainwave Entrainment Symposium, Stanford, May 2006
Fundamental problems • Subjective time-frame (reference) • Signal processing requirements Brainwave Entrainment Symposium, Stanford, May 2006
Subjective time-frame (transcendence?) t Mind t’ = F(t) t’ F - non linear function Measurement equipment
Signal Processing Requirements • Most processing algorithms require large number of samples • FFT of 1024 points @ 256 Hz 4 seconds • Time-frequency tradeoff • Wavelet analysis • Short events are lost Brainwave Entrainment Symposium, Stanford, May 2006
EEG visualization methods Brainwave Entrainment Symposium, Stanford, May 2006
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 Brainwave Entrainment Symposium, Stanford, May 2006
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 Brainwave Entrainment Symposium, Stanford, May 2006
Sonification - approaches • Rhythm • Pitchsubjective perception of frequency • Timbrecharacteristic of instrument generating sounds • Loudness (volume) • Location of sound source • balance of stereo sound Brainwave Entrainment Symposium, Stanford, May 2006
Rhythm • Very powerful method • Natural use of very low frequencies • Delta and Theta frequencies • Complex patterns is sub-Delta band Brainwave Entrainment Symposium, Stanford, May 2006
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: 1007-1000=7Hz • Fine control of the entrained frequency Brainwave Entrainment Symposium, Stanford, May 2006
Holistic Approach • Mental processes (EEG) • Breathing • Heart rate • Cardiovascular system • Glands & Hormons • Body functions Brainwave Entrainment Symposium, Stanford, May 2006
After Before LF/HF=146 During Example #1: Yogic breathing (1 b/min) Brainwave Entrainment Symposium, Stanford, May 2006
Example #2: Chanting Brainwave Entrainment Symposium, Stanford, May 2006
R L R L Frequency The Awakened Mind (C. Maxwell Cade) • The importance of different frequency bands • Holistic approach Brainwave Entrainment Symposium, Stanford, May 2006
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 Brainwave Entrainment Symposium, Stanford, May 2006