Brainwave Entrainment and Beyond: Toward Holistic Approach

1. 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

2. 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

3. 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

4. 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

5. Brainwave Frequencies Brainwave Entrainment Symposium, Stanford, May 2006

6. EEG Correlates of Conscious States

7. EEG Correlates of Conscious States (II)

8. 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

9. 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

10. Fundamental problems • Subjective time-frame (reference) • Signal processing requirements Brainwave Entrainment Symposium, Stanford, May 2006

11. Subjective time-frame (transcendence?) t Mind t’ = F(t) t’ F - non linear function Measurement equipment

12. 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

13. EEG visualization methods Brainwave Entrainment Symposium, Stanford, May 2006

14. 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

15. 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

16. 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

17. 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

18. 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

19. Holistic Approach • Mental processes (EEG) • Breathing • Heart rate • Cardiovascular system • Glands & Hormons • Body functions Brainwave Entrainment Symposium, Stanford, May 2006

20. After Before LF/HF=146 During Example #1: Yogic breathing (1 b/min) Brainwave Entrainment Symposium, Stanford, May 2006

21. Example #2: Chanting Brainwave Entrainment Symposium, Stanford, May 2006

22. 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

23. 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