TMI Journal 2009-1&2 (Winter/Spring)

Journal TMI Vol. I Winter/Spring 2009 Nos. 1 & 2 A Research and Educational Publication of The Monroe Institute Editors: Shirley Bliley, Ann Vaughan Layout & Design: Grafton Blankinship The TMI JOURNAL, a publication of The Monroe BINAURAL BEATS AND THE Institute®, an educational and research organization REGULATION OF AROUSAL LEVELS dedicated to exploring and developing the uses and understanding of human consciousness, offers current reporting on research and application of by F. Holmes Atwater, BA binaural-beat technology in a variety of professional fields. Abstract The TMI JOURNAL is published by The Monroe Institute, 365 Roberts Mountain Road, Faber, VA This paper describes two studies. A first study 22938-2317. Telephone: (434) 361-1252. Membership measured the neural accommodation (changes in ongoing rates from $50 to $100 per year. or overall brain-wave activity) associated with complex © 2009 The Monroe Institute. All rights reserved. No binaural-beat stimuli. A second study, based on the same part may be reproduced without permission. protocol, measured changes in ongoing brain-wave activity associated with placebo stimuli. A weak EEG frequency-following response to binaural beating and other rhythmic stimuli manifests using either inhibits or excites areas of the cortex by neutralizing time-domain averaging brainwave analysis techniques. or enhancing the effects of noradrenaline and serotonin Theoretically, this frequency-following response emerges coming to the cortex via “fountains” from the locus as a low-amplitude linked series of evoked-potential coeruleus and the raphe nuclei. responses. It is important to note that these studies examined ongoing brainwave activity (in this case, central Key Words: ERTAS, reticular, frequency-following delta and occipital alpha) and not the frequency-following response, sound, binaural beats, brainwaves response. Background Results of the two studies showed that during the binaural-beat stimuli, reductions in the percentages A look at the auditory phenomenon known as binaural of occipital alpha (bipolar O1–O2) were significant beating provides a unique opportunity to understand the (individually, p < .05, and together, p < .001) during five power of rhythmic sound and music to influence arousal. of six free-running EEG recording periods compared to The sensation of “hearing” binaural beats occurs when baselines. During these same recording periods, reductions two coherent sounds of nearly similar frequencies are in the percentages of central delta (bipolar C3–C4) were introduced by stereo presentation one to each ear. Phase similarly significant during four of six periods compared differences between these sounds engender a perceived to baselines. Alpha- and delta-brainwave changes were vibrato or wavering at the frequency of the difference nonsignificant during the placebo stimuli. between the two (stereo left and right) auditory inputs The extended reticular-thalamic activating system called the binaural beat. (ERTAS) may be the neural mechanism behind the Binaural beating originates in the brain stem’s two observed brainwave changes. The reticular formation of superior olivary nuclei (Oster 1973). Beating-frequency the brain stimulating the thalamus and cortex (referred information neurologically passes to the reticular formation to as the ERTAS) governs cortical brainwave patterns. (Swann et al. 1982). This information is said to be Acetylcholine, provided via cortico-thalamic projections, simultaneously “volume conducted” to the cortex and Next Page TMI JOURNAL Winter/Spring 2009 objectively measured by EEG as a frequency-following be externally initiated using auditory drubbing found in response (Oster 1973; Smith et al. 1975; Marsh et al. rhythmic music, drumming, or the unique phenomenon 1975; Smith et al. 1978; Hink et al. 1980). This cortical known as binaural beating. Perceived binaural beating measurement was termed the “frequency-following indicates the presence of a coherent oscillation within the response” because its period (frequency in cycles per brain stem’s two superior olivary nuclei as evidenced by the second) corresponds to the frequency of the beat stimulus cortically measured frequency-following response (Oster and the oscillation present in the olivary nuclei and 1973; Hink et al. 1980). As with other rhythmic sound subsequently the reticular formation (Smith et al. 1975). patterns, the low-level coherent oscillation (within the The EEG frequency-following response, an objective, superior olivary nuclei) that accompanies binaural beating instrumented observation, strongly suggests that the appears to regulate arousal states by providing frequency perceived binaural beating is, in fact, the result of a low- information to the extended reticular-thalamic activating level coherent oscillation within the central nervous system system (ERTAS) and thereby inducing fluxes in cholinergic and the brain stem in particular. neurons or the “gatelets” of the nucleus reticularis. Binaural beats can easily be heard at the low First Study frequencies that are characteristic of the brain-wave The first study examined the degree to which complex spectrum (Oster 1973; Hink et al. 1980; Atwater 1997). binaural beats influenced ongoing brainwave activity (in The existence of an externally initiated, internally present this case, central delta and occipital alpha). Ongoing or low-level coherent oscillation (perceived as binaural dominant brainwave activity can be referred to as cortical beating) within the central nervous system, and specifically levels of arousal. the reticular formation, suggests a condition that may facilitate alterations of levels of cortical arousal. Hypothesis There have been numerous anecdotal reports and a Listening to binaural beats for several minutes growing number of research efforts reporting changes will modify ongoing brainwave activity. Increasing the in consciousness associated with binaural beats. The amplitude of delta-frequency binaural-beat stimuli while audio phenomenon known as binaural beating has been decreasing the amplitude of alpha-frequency binaural- associated with changes in arousal leading to sensory beat stimuli will result in comparable changes in arousal as integration (Morris 1990), alpha biofeedback (Foster measured by free-running EEG. 1990), relaxation, meditation, stress reduction, pain Method management, improved sleep (Wilson 1990; Rhodes During this study 20 volunteer subjects remained supine 1993), health care (Carter 1993), enriched learning in a darkened, sound-attenuating chamber. Subjects reported environments (Akenhead 1993), enhanced memory normal hearing with the exception of one subject who had (Kennerly 1994), creativity (Hiew 1995), treatment of a bilateral hearing loss and for whom the volume of the children with developmental disabilities (Morris 1996), stimuli was raised to a comfortable level to compensate for the facilitation of attention (Guilfoyle and Carbone 1996), said hearing loss. None of the subjects reported a history of peak and other exceptional experiences (Masluk 1998, mental, emotional, or nervous-system disorders. 1999), enhancement of hypnotizability (Brady and Stevens The experimental binaural-beat stimuli consisted 2000), treatment of alcoholic depression (Waldkoetter and of mixed sinusoidal tones producing complex frequency Sanders 1997), and promotion of vigilance performance patterns (waveforms) changing over a period of 45 minutes. and mood (Lane et al. 1998). The stimuli were presented with stereo earphones at 40 Theoretically, sound waves exhibiting a frequency- dB above subjective threshold. The volunteer subjects first following response may be effective in the regulation of experienced a no-stimulus baseline condition during which arousal levels by way of inducing fluxes in cholinergic a 90-second EEG recording was taken. Next, each subject neurons or the “gatelets” of the nucleus reticularis. listened to the same 45-minute sequence of changing The concept here is that the binding of acetylcholine binaural beats (see Figure 1) during which six 90-second to cholinergic neurons (Scheibel 1980; Macchi and EEG recordings were taken at regular intervals. To reduce Bentivoglio 1986; Groenewengen and Berendse 1994 [all the influence of expectation, subjects were blind as to cited in Newman 1997a]) or the “gatelets” of the nucleus the character of the tones presented during the stimulus reticularis is affected by these sounds when the rhythmic condition. Finally, during a no-stimulus post-baseline patterns become neural oscillations within the brain stem. condition, a 90-second EEG recording was made (see These changes within the cholinergic neurons can Figure 2). Next Page ii TMI JOURNAL Winter/Spring 2009 Figure 1. Changing delta and alpha binaural-beat stimuli Figure 2. EEG recording periods Next Page iii TMI JOURNAL Winter/Spring 2009 Subjects were connected to a 24-channel digitizing EEG computer (NRS-24, Lexicor Medical Technology Inc., Boulder, Colorado) using V151 software and the entire standard 10/20 International System montage of electrodes. The 19 active EEG channels and reference electrode placements were tested to ensure the lowest possible contact resistance and balanced impedance level. A sampling rate of 256 samples per second was used, which provided for an EEG frequency response of 1-64 Hz (less 60 Hz, due to a notch filter), a frequency resolution of 1 Hz, and a temporal resolution of one second. The audio patterns cross-faded smoothly from one complex stimulus waveform to another during the 45-minute binaural-beat protocol. Detailed below are the audio stimuli experienced by the subjects during the designated EEG recording periods: Left-Ear Right-Ear Volume EEG Recording Periods 50 Hz 50.75 Hz 40% First @ 3 Minutes 100 Hz 101.5 Hz 32% 200 Hz 207 Hz 28% 50 Hz 50.75 Hz 40% Second @ 8 Minutes 100 Hz 101.5 Hz 32% 200 Hz 205 Hz 28% 50 Hz 50.5 Hz 29% Third @ 14 Minutes 75 Hz 75.75 Hz 26% 100 Hz 101.5 Hz 24% 200 Hz 204 Hz 21% 50 Hz 50.75 Hz 20% Fourth @ 22 Minutes 100 Hz 101.5 Hz 18% 125 Hz 126.25 Hz 25% 200 Hz 204 Hz 15% 200 Hz 202 Hz 22% 50 Hz 50.75 Hz 24% Fifth @ 30 Minutes 100 Hz 101.5 Hz 23% 200 Hz 204 Hz 35% 325 Hz 328.5 Hz 12% 525 Hz 530.25 Hz 6% 50 Hz 50.75 Hz 29% Sixth @ 38 Minutes 100 Hz 101.5 Hz 28% 200 Hz 204 Hz 36% 850 Hz 858.5 Hz 4% 1,375 Hz 1,397.25 Hz 3% Results The data on two subjects were rejected due to movement artifact. WINKS Professional Edition statistical software (TexaSoft, Cedar Hill, Texas) was used to provide a multiple comparison procedure following a one-way ANOVA (Dunnett’s test) comparing the combined baselines as a control mean with the binaural-beat stimulus periods for the remaining 18 subjects. This analysis showed that the reductions in the percentages of occipital alpha (bipolar O1–O2) during stimuli conditions were significant (individually, p < .05) during five of six stimulus periods compared to baselines (see below). Next Page iv TMI JOURNAL Winter/Spring 2009 Analysis Summary for Occipital Alpha - Stimulus Condition Means and standard deviations for percent occipital alpha: Baselines: mean = 30.469 s. d. = 6.6197 n = 18 Period 1: mean = 27.186 s. d. = 5.8456 n = 18 Period 2: mean = 25.2613 s. d. = 5.2129 n = 18 Period 3: mean = 23.9439 s. d. = 6.5893 n = 18 Period 4: mean = 24.4362 s. d. = 6.8506 n = 18 Period 5: mean = 23.2225 s. d. = 5.4852 n = 18 Period 6: mean = 21.6931 s. d. = 4.5623 n = 18 Analysis of Variance Table Source -S.S.- -DF- -MS- -F- Approx. p --------------------------------------------------------------------------------------------- Total 5090.45 125 Treatment 901.35 6 150.23 4.27 < .001 Error 4189.1 119 35.2 --------------------------------------------------------------------------------------------- Error term used for comparisons = 35.2 with 119 d. f.