EEG Changes After Bhramari Pranayama Rajkishore Prasad1, Fumitoshi Matsuno1, Hovagim Bakardjian 2, Francois Vialatte2 and Andrzej Cichocki2 1
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TH-F3-4 SCIS&ISIS2006 @ Tokyo, Japan (September 20-24, 2006) EEG Changes After Bhramari Pranayama Rajkishore Prasad1, Fumitoshi Matsuno1, Hovagim Bakardjian 2, Francois Vialatte2 and Andrzej Cichocki2 1. Man Machine Interface Lab., University of Electro Communication, Japan 2. Brain Science Institute, RIKEN, Japan E-mails :1.{ kishore,matsuno}@hi.mce.uec.ac.jp, 2. {hova, fvialatte, cichocki}@brain.riken.jp Abstract—This paper presents changes in the EEG pattern observed after Bhramari Pranayama (BP) or bee like breathing exercise. BP has been found effective in healing many mental problems such as tension, stress, hypertension, etc and it brings relaxation in the practitioners of it. It has also been said that BP is very quick in producing results. The analysis of EEG data recorded before and after BP shows similar and positive changes in different brainwave patterns, related to relaxed state, both for an experienced and a new subjects. Index Terms—yoga, EEG, relaxation vibro-acoustic, Bhramari pranayama. Fig.1 One of the easiest body posture for doing Bhramari Pranayama. Subject plugs ear by finger and makes humming sound with exhalation through nasal airways. I. INTRODUCTION hramari Pranayama (BP) is one of the important types of eye brows, middle fingers are used to press root of the nose B yoga related with breath control. Today yoga is well near the corners of the eyes and other fingers are placed along introduced and is well accepted health caring practice in nose such that little fingers lie below. Different variants of BP everyday's life. Regular practice of Yoga is preventive, curative differ mainly in body posture. In on of its difficult form and recuperative. It helps healing process to accelerate process humming sound is made both during exhaling and inhaling. of recovery [1],[2]. The most ancient use of the word yoga can While doing BP concentration is kept at the third eye point be found in the oldest ritual books, known as VEDA, of Indian located between eyebrows as shown in Fig.1. The volume of civilization, however, it has been assumed that Yoga was humming should be loud enough for vibrations in the brain. originated in India nearly 6000 years ago as a part of Indian The humming sound should be steady and not wavering like a traditional treatment system known as Aryuveda. All the motorcycle starting up. It should be effortless and mellow. ancient records available on the effects and benefits of yoga Healing effects of BP are numerous, however, it has been have been results of subjective observations of different sages, mainly recommended for reducing mental problems such as rishis (ancient Indian researchers) and yoga masters, for tension, cerebral tension, hypertension, anxiety and controlling thousands of years. However, in the modern age, studies have blood pressure [6],[7],[8]. It has also been said that it brings been started on different yogic acts using modern scientific bliss and improves psychic sensitivity and awareness for subtle methods and many validatory results have been reported too sound vibration. However, very few scientific studies on [3],[4],[5]. effects of this pranayama have been done. In [7], authors made Pranayama is also a type of yoga popularly known as Hath studies on effects and benefits of BP on the pregnant women yoga. Practice of Hath yoga in some sense is common with and have concluded with great usability of it for the preparation Raja Yoga or Power Yoga. According to Hath Yoga Pradipika, for labor. In one of our very recent studies [9], first two authors an ancient Indian text on Hath yoga, Hath yoga leads to Raja have shown that humming sound produced during BP and that Yoga [6]. The Sanskrit word Pranayama contains two of bumble bee bears similarity in spectral contents and have meaningful segments namely Prana (this means vital force) proposed that humming sound plays key role in the healing and Yama (this means control). So pranayama literally means a process of the BP. In the present study we provide some of our yogic act performed for controlling flow of the vital energy that observations on changes in EEG brainwaves after performing governs all the physiological process of our body. There are BP. To best of our knowledge no EEG study has been made on many types of pranayama among which BP is an important BP in past, however, many EEG studies have been made on item [6]. The term Bhramari is also a Sanskrit word which in different types of pranayama. For example, in [10],[11] EEG this context means like a bumble bee. Thus in BP subject has to studies on alternate nostrils breathing pranayama has been produce sound like bumble bee while exhaling strictly through made and it has been shown that it improves balances between nasal airways, keeping oral cavity closed at the lips, ears closed right and left hemispheres of the brain. In other studies on the by fingers and eyelids are also shut down. There are many yogic breathing it has been reported that pranayamas are variants of BP. One of the easiest body posture during BP is effective in improving cognitive performance, bringing shown in Fig.1.In another variants ear is closed by thumb by relaxation, improving spatial memory performances [12]. In pressing ear flaps and putting index finger on forehead along [13], EEG study on Sudarshan Kriya, a type of pranayama, has been done. Based on such studies we also decided to make EEG - 390 - studies on the BP as it has been found useful in reducing mental Separation (BSS) algorithm which estimates independent problems and most importantly it has been said that it is very components of the signal and arrange them in the decreasing quick in bringing effects. order of their variance and linear predictability. The EEG Rest of the paper is organized as follows. In the Section II study components corresponding to artifacts will have lower values methods have been dealt. In Section III EEG data analysis of variance and linear predictability which can be eliminated methods and results have been presented. Section IV presents and rest components can be used to reconstruct the sensor conclusions and future research work which are followed by signals known as deflated signals [15]. Similar approaches references. have been used here too. Fig.3 shows raw EEG data at 21 sensors and Fig.4 shows EEG data obtained after AMUSE II. EEG RECORDING AND METHODS filtering where it can be seen how components have been In this preliminary study two subjects were chosen one with 4 arranged in order of increasing complexities. months regular experience of BP and other with no prior It is an established fact that level of consciousness is related to experience of BP, however, second subject was trained for how different brainwaves signals known as delta (δ ) wave with to do BP before the EEG recording. Subjects were chosen from different cultural and ethnic groups. Subjects with such contrast were chosen to see if the BP produces quick effect or not and if it can works in similar ways on different people. In this study our aims have been to objectify effect of BP, so experiment was designed to record EEG before BP and after BP. The BP was done for 15-20 rounds by each subject. EEG was recorded with 128 channel BIOSEMI system at RIKEN, Japan. The sensor layout used in the EEG recording is shown in Fig. 2. For the purpose of analysis, we selected the sensor positions located in the part of temporal lobe, parietal lobe and frontal lobe from both the left and right sides of the head. The reason for this is based on the fact that in BP concentration is kept at the third eye point which has biological connection with the pineal gland. Also, the humming sound is produced in BP and its interaction will be related with the temporal lobe of the brain. In this way total 21 sensor signals were chosen covering all these regions. The selected EEG signals were filtered using AMUSE algorithm [14] . AMUSE algorithm is a Blind Signal Fig.3 Raw EEG signals at for 21 sensors (x-axis time in sec, scale is arbitrary). Fig.2 Sensor layout of 128 Channel biosemi system. Radial Fig.4 AMUSE filtered EEG signals arranged in order of positions of the sensor locations were a little modified to forbid increasing complexities (x-axis time in sec, scale is partial overlaps in figure. arbitrary). - 391 - frequency range 0.2 Hz to 4 Hz, theta (θ ) wave with frequency state. This is related with waking dream and responsible for range 4Hz to 8 Hz, alpha (α ) wave with frequency range 8Hz flashing vivid imageries before the minds eye. It has been to 14 Hz, beta ( β ) wave with frequency range 14 Hz to 30 Hz identified as gateway of learning. Its dominance increases and Gamma ( γ ) wave with frequency range 30 Hz to 80 Hz. creativity, learning, reduces stress, awakens institution and other extraordinary perception skills. There have been The EEG signal obtained from AMUSE algorithm were passed consistent reporting in many previous research papers that through zero phase shift band pass filters with pass bands during relax state theta activity increases [16],[17],[18]. As it corresponding to that of δ ,θ,α, β,and γ brainwaves to filter can be imbued from Fig.5, Fig 6, Fig.7 and Fig.8 that there are out these signals. The temporal variation of Relative Spectral considerable changes in RSP of theta activity of the both Power (RSP) defined as the ratio of Band Spectral Power (BSP) subjects.