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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 2  |  Issue : 1  |  Page : 13-18

Fast fourier transform transformed, electroencephalography correlates of introduction to meditation and transcendence shift in novices


1 Department of Physiology, AIIMS, Rishikesh, Uttarakhand, India
2 Department of Physiology, AIIMS, New Delhi, India

Date of Submission09-May-2020
Date of Decision23-Jul-2020
Date of Acceptance09-Feb-2021
Date of Web Publication25-Apr-2021

Correspondence Address:
Dr. Ratna Sharma
Department of Physiology, AIIMS, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JME.JME_18_20

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  Abstract 

Objectives: The objectives of the study were to explore the fast Fourier transformation (FFT)-transformed individual alpha frequency (IAF)-based electroencephalographic (EEG) correlates of introduction to a special type of meditation, and transcendence shift in meditation novices.Methods: The study was conducted on 34 healthy male student volunteers. The participants were introduced to 15 min of a special type of meditation under the supervision of an expert. EEG was recorded from 19 scalp locations according to the 10–20 international system of electrode placement. To overcome the problems of the fixed band system, IAF-based band method was adopted. The outcome measures were FFT-transformed absolute powers (APs) in the six bands at 19 electrode positions. These outcome measures were analysed for early, middle and late phases (5 min each) of the meditation and compared with the relaxed eyes-closed mental state as the control in the same participants. Results: The special type of meditation showed a trend of decrease in AP over increasing electrodes' positions in theta, lower 1 alpha and lower 2 alpha with progression. However, power in the beta band was consistently decreased, while upper alpha (except in C3) and gamma-band power remained unchanged throughout the meditation. Conclusions: Introduction to a special type of meditation has distinct EEG correlates and resembles a deeper relaxed focus of attention and partial transcendence as compared to the simple relaxation with eyes-closed-state in the novice's participants.

Keywords: EEG, fast Fourier transformation, meditation, transcendence


How to cite this article:
Singh Y, Sharma R. Fast fourier transform transformed, electroencephalography correlates of introduction to meditation and transcendence shift in novices. J Med Evid 2021;2:13-8

How to cite this URL:
Singh Y, Sharma R. Fast fourier transform transformed, electroencephalography correlates of introduction to meditation and transcendence shift in novices. J Med Evid [serial online] 2021 [cited 2022 Aug 12];2:13-8. Available from: http://www.journaljme.org/text.asp?2021/2/1/13/314620


  Introduction Top
Meditation is increasingly becoming popular across the world and is a widely utilised intervention for stress management and positive health. In western culture, mediation is considered as a set of techniques, which strive to train attention and its focus. One of the most ancient theoretical constructs of psychology is the faculty of attention and meditation is best described as regulation and training of attentional network or cycle of volitional and spontaneous cognitive processes.[1],[2] Meditation is broadly classified into directive and non-directive types based on how and which type of attention is utilised. In directive meditations, the attention is actively directed with the effort to the object of meditation, while in non-directive meditations, a relaxed focus of attention is established effortlessly.[3],[4],[5] Further, the directive meditation is of two types depending on whether the attention is either directed towards the object of the meditation or the spontaneous flow of the experiences and is classified as focused attention (FA) and open monitoring type of meditation, respectively.[6] The third category of mediation as proposed by Travis and Shearc'Automatic self-transcending' is described as a set of unique practices (Vedic and Chinese practices) or it may not be a true sacrosanct category as it may be the emergent outcome of previous two categories.[7] The automatic self-transcending is distinct as it has the absence of individual control or effort and focus of attention. However, these three meditation categories may not be mutually exclusive within a single session or throughout long-term meditation practices. In the meditation practices, various cognitive processes are utilised (attention, feeling, reasoning and visualisation), which get further compounded by the objects of meditation (thoughts, images, emotions and breath) and the way these processes are used temporally and spatially from minimal to highly controlled cognitive processing resulting in the emergence of dynamic unique brain patterns'.[8] These 'unique brain patterns' could provide an 'objective language' for the procedures and experiences resulting from different types of meditation practices. Electrophysiology of these 'unique brain patterns' of meditation can be studied by the electroencephalography (EEG). The different EEG wave patterns reflect the quantitative measurement of spatial and temporal brain electrical activity. From a neurophysiological point of view, these different forms of EEG wave patterns are mainly determined by the different cognitive processes, different ranges of attention and different subject–object content of experience generated during different types of meditation.[7] Scientific literature is flooded with electrophysiological studies of long-term meditation correlates with absolute powers (APs) in classical EEG bands. However, evidence from literature reports suggests that the 'unique brain patterns' vary significantly with the level of meditation practice, and the beginner level meditation practitioners have distinct EEG correlates when compared to the advanced level.[9] There are few studies in the literature on electroencephalographic (EEG) correlates of introduction to meditation in novices. In the present study, we have designed a special type of 15-min mediation (with the help of experts) which begins with non-directive meditation but gradually and smoothly shifts to automatic self-transcending type with progression. We want to hypothesise and test that the transition from a non-directive mediation state to an automatic self-transcending state is an effortless and spontaneous process. In the present study, we would like to explore the FFT-transformed EEG correlates of introduction to a special type of meditation and transcendence shift in meditation novices.
  Materials and Methods Top
The study was conducted on 34 male volunteers. Participants with a history of practicing meditation, relaxation techniques, indulging in substance abuse, smokers, alcoholics or those known to be having any medical disease or undergoing treatment for any medical condition were excluded. Moreover, all the experiments were done in the forenoon to minimise the diurnal variation. Ethical clearance for the study was obtained from the institutional ethical committee. Participants were briefed about the study with the help of the information sheet and informed written consent for participating in the study was obtained. Study setting and population The study population included students, healthcare workers and staff of tertiary care hospital. Meditation Participants were introduced and taught a special type of 15-min mediation by an expert instructor which begins with non-directive meditation but gradually and smoothly shifts to automatic self-transcending type. Throughout the meditation session, participants were sitting with closed eyes. In this meditation for the first few minutes, participants in a relaxed state gently observed on their breathing. Subsequently, it was followed by a stage, when with each breath, participants were guided to experience peace, stillness and thoughtlessness. As soon as the mind reached the thoughtless, peaceful stage or transcendence stage, participants had to just remain and maintain the status quo state of the transcendence stage. The participants were also instructed for the option of repeating the autosuggestion if it was conducive for shifting in the stage of transcendence from mind wandering. EEG signal acquisition and analysis Before recording, participants were instructed to clean their hair with shampoo without any conditioner and oil. The scalp was cleaned first with an alcohol swab followed by rubbing with 'SKINPURE' skin preparation gel (supplied by Nihon Kohden) to decrease impedance between electrodes and scalp. Electrodes were placed on the scalp according to the 10–20 international electrode placement system with the help of 'Elefix' paste for EEG (supplied by Nihon Kohden), following which dry cotton was placed on the electrodes to prevent motion artifacts. Impedance was checked and was kept below 5 k. Silver–silver chloride (Ag-AgCl) disc-type electrodes of 5–7 mm diameter with long flexible lead were used. EEG signal was acquired on RMS EEG-19 Superspec system at a sampling frequency of 256 Hz using high pass (1 Hz), low pass (70 Hz) and notch (50 Hz) filter with a sensitivity of 7.5 µV/mm and sweep speed of 30 mm/s. Signal analysis To overcome the problems of the fixed band system, the individual alpha frequency (IAF)-based frequency band division method was used.[10] To determine IAF, fast Fourier transformation (FFT) was applied to baseline epochs at the PZ electrode position. The peak power frequency among 8–12 Hz was designated as IAF. Frequency bands were determined individually for each subject by using IAF as the cutoff point between the lower and upper alpha bands. Six EEG frequency bands were analysed: (1) theta band: IAF −4 Hz to IAF −6 Hz, (2) lower 1 alpha band: IAF −2 Hz to IAF −4 Hz, (3) lower 2 alpha band: IAF to IAF −2 Hz, (4) upper alpha band: IAF to IAF + 2 Hz, (5) beta band: IAF +2 Hz to 30 Hz and (6) gamma band: 30 Hz to 70 Hz. An average of 10 epochs of different conditions was analysed for the AP, i.e., root mean of area under the power spectrum of a given band, expressed in microvolts squared. Statistical analysis The statistical analysis and box plotting were done using R Software version 3.1. (Free and open-source software developed by R Core Team, Auckland, New Zealand). The meditation phase was divided into early (M1), middle (M2) and late phase (M3) of 5-min duration each. The controls for the meditation phase were relaxed eye-closed phases in the same participants. The external controls in the meditation studies have their limitations; therefore, we opted for this type of study design. The relaxed eyes-closed phase preceded the mediation phase to avoid the spillover of the meditation session. The distribution of the data was found to be non-Gaussian type; therefore, non-parametric test (Wilcoxon Signed-rank test) was applied. P < 0.05 was considered significant.
  Results Top
The average age of the participants was 24.4 years (age range: 18–30 years; mean + standard deviation, 24.4 ± 3.2 years). All the participants had a graduate or higher education level. State effect of meditation on EEG The state effect of meditation on EEG was divided into three phases, early, mid and late phases of 5-min duration each. Analysis of EEG is expressed for AP. The results of EEG during meditation were compared with basal eye close recording [Box Plot 1], [Box Plots 2], [Box Plots 3].

Early phase of meditation (M1) As compared to basal eye close power, during early mediation, AP decreased mainly in frontal electrodes of the beta band (FP1, FP2, F7, F3, F4 and F8), while increased power was seen in theta (C3 electrode) and upper alpha band (P3 electrode). There was no change in the AP of lower1 alpha, lower 2 alpha and gamma band. Mid phase of meditation (M2) During this phase, AP was decreased in most of the leads in the lower 2 alpha band, the beta band (FP1, FP2, F7, F3 and FZ) and in one position of lower 1 alpha band (T5). There was no change observed in the AP of theta, upper alpha and gamma band. The late phase of meditation (M3) During the late phase of meditation, decreased AP was seen mainly in the lower 2 alpha band but also beta band (FP1, FP2, F3, F4, T3, T5, CZ and P3), lower 1 alpha (PZ and P4) and theta band (F7, T4, T5, T6 and P4). However, upper alpha and gamma band AP did not change in this phase.
  • Box plot is an effective way to visualise the entire range of a large dataset, it is constructed using the median value, 25–75 quartile segment and full distribution range of EEG data
  • In the box plot, color codes for different EEG bands are in the following manner: green = theta blue = lower 1 alpha, yellow = lower 2 alpha, purple = upper alpha, orange = beta and black = gamma
  • In X axis, various electrodes, and band names are abbreviated using the following scheme:
For example, 'FP1T' represents theta band's AP comparison at the FP1 electrode position. First, we have written Electrodes' position followed by the band name. Different band name is abbreviated as follow: T = Theta, LA1 = Lower 1 Alpha, LA2 = Lower 2 Alpha, UA = Upper Alpha, BT = Beta and G = Gamma.
  Discussion Top
In the present study, participants underwent the intervention of 15 min of special mediation which started with non-directive meditation but gradually shifted to automatic self-transcending type. Out of the two objectives, the first objective was to explore the FFT-transformed EEG correlates of introduction to this special type of mediation in the novices. The meditation intervention was associated with significant AP differences in various alpha, beta and theta bands as compared to a relaxed eye-closed state. We found an interesting trend of a decrease in the AP in lower alpha 2 and theta bands with the progression of meditation. However, in the early phase of meditation, increased power in theta at the C3 electrode was found which reflects the index of monitoring of the inner mental process. The AP in the beta band was decreased in most of the position of the electrodes throughout the whole session, while upper alpha (except C3) and gamma-band power remain unchanged. Since the work of Hans Berger (1873-1941), alpha waves represent wakeful relaxation during eye-closed state predominantly originating from the occipital lobe of the brain.[11] However, studies involving IAF-based EEG analysis have a totally different and unique picture. The traditional alpha band ranges from 8 to 13 Hz, however, the modern IAF-based analysis has a distinct three alpha sub-band (lower 1 alpha, lower 2 alpha and upper alpha band) and these bands may have an overlapping zone with old theta band range. Literature finding from the studies of EEG and performance during the different types of cognitive tasks suggests that low- and high-frequency rhythms are associated with specific cognitive processes (namely attention, alertness semantic memory, task load, expectancy, binding, feeling, decision-making, reasoning, imagery and visualisation).[6],[10] Alpha 1 band is the index to alertness, expectancy, task demands, and attentional processes and alpha 2 appears to index, engagement of specific brain modules used in task performance.[12],[13],[14],[15] In our study, we have found decreased power in the lower 2 alpha band and no change in lower 1 alpha power (except few positions) and it is suggestive of classical cortical idling, i.e., participants had a relaxed focus of attention and were not involved in any specific task. Upper alpha desynchronisation is typically seen during the processing of sensory-semantic information acquisition and processing.[16],[17],[18],[19],[20] In our study, no change in upper alpha power reflects that participants were experiencing a relaxed mental state and they were not actively engaged in the specific task or semantic monitoring process of ongoing experience. This relaxed mental state is further supported by the decreased power in the theta band. The frequency rhythm in the theta band is reported in tasks requiring self-control and is a neural index of monitoring of inner processes of self and is supposed to originate in medial prefrontal and anterior cingulate cortices (structure related to self and self-control).[21] Therefore, decreased power in the theta band is suggestive of a relaxed mental state/self. The core psychological components of mental practices such as meditation are relaxed attention and mindfulness which has a lot of psychotherapeutic and clinical importance.[22] Several studies have demonstrated the beneficial effects of meditative practices on perception,[23] cognition.[24],[25] emotional processing[26],[27] and neuroplasticity.[28],[29],[30] Finding from the meta-analysis of neuroimaging studies on meditation practice has been associated with changes in the morphology of the prefrontal cortex and body awareness regions.[31] Such changes might have a potentially positive impact on brain functioning. The second objective of the study was to test the hypothesis that the meditation novice participants during their introduction to a special type of meditation (the type which is conducive for the transcending) can undergo the self-transcending spontaneously and effortlessly. Transcending is subjectively characterised by the absence of time, space and body sense.[32] Literature suggests that the classical frequency band of automatic self-transcending is chiefly higher frontal alpha 1 and lower beta 1 and gamma power.[33] The EEG results of our study during the meditation are suggestive of partial transcendence. A consistent progressive decrease in the beta band power with the progression of meditation suggests automatic self-transcending; however, there was no change in lower 1 alpha and gamma band power. Higher gamma-band activity is a classical finding in experienced meditators and positively correlates with the length of lifetime meditation practice.[34 ]As our participants were novices to the meditation, we expected no change in gamma-band power.[34] Beta 1 (13-20 Hz) activity has been associated with the binding of sensory inputs into a unified perception, such as integration of visual and auditory information and unified construction of the content of experience.[35],[36],[37] Furthermore, higher activity in the beta 2 and gamma bands is seen in those meditation practices that involve highly FA to a specific object.[38] Hence, a decrease in beta activity in our study may suggest that participants were not in the state of FA and there was an absence of any type of active semantic process, self-regulation and monitoring of sensory experience. Indirectly, it is suggestive of the beginning stage of transcendence. The mind has a natural capacity to transcend its activity and acquiring this faculty would have been a big survival advantage in the processing of information in a more meaningful manner, particularly in the present world scenario where the mind is overburdened, stressed, tensed and bombarded with loads of the conflicting information all the time. The acquisition of this natural capacity to transcend, i.e., automatic moving of attention to a mental relaxed state or ability to disengage and become free or content less may provide a big relief to shut the active processing of attention and get lighter and relaxed. However, this natural capacity to transcend may be useful only up to a limit. The natural tendency of the mind to transcend its activity has been identified and optimally developed through various techniques since ancient times in various spiritual and meditation traditions. In the Transcendental meditation technique, the automatic transcending is claimed to be present from the outset of meditation practice and no extensive practice is required.[26] The integration of the meditation experience with daily activity and phenomena of experience-related neuroplasticity can further foster the development of this natural brain state to transcendence its state.[39] Physiologically, the integration of transcendental experiences with waking, dreaming and sleeping can foster higher brain integration, greater emotional stability and decreased anxiety during challenging tasks.[40] Finally, the main limitation of our study is the small sample size, and one specific education class of participants and the results of the present study may be specific to the type of participants selected, their perception and interest in meditation. The rate and extent of transcendence may also vary, from person to person, and type of meditation, owing to differences in the mind and body when one sits for the meditation.
  Conclusions Top
Introduction to a special type of mixed meditation has distinct EEG correlates and resembles a deeper relaxed focus of attention as compared to the simple relaxation with eyes-closed state in the meditation novices. Some EEG wave patterns such as the progressive consistent decrease in the beta band are suggestive of partial transcendence. Recommendation Directive types and mixed types of meditation practices are capable of inducing a deeper relaxed mental state and can be practiced as a relaxation technique in healthy population and chronic stress disorders. Acknowledgements This work was supported by a financial grant from the All India Institute of Medical Sciences, New Delhi, India. We would like to acknowledge and thank Dr. Nilotpal Chowdhury, Additional Professor, Department of Pathology and Laboratory Medicine, All India Institute of Medical Sciences Rishikesh, for his valuable contribution in making of Box plots for the EEG analysis and representation. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

 
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