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Neuro-hemodynamic effects of mantra recitation  "OM"

Authors: Bangalore G Kalyani, Ganesan Venkatasubramanian, Rashmi Arasappa, Naren P Rao, Sunil V Kalmady, Rishikesh V Behere, Hariprasad Rao, Mandapati K Vasudev, Bangalore N Gangadhar

Department of Psychiatry, Center for Advanced Yoga, National Institute of Mental Health and Neuroscience, Bangalore, Int J Yoga - 560 029, India

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Background : During the recitation (chanting) of the mantra “OM” a feeling of vibration affects the stimulation of the vagus nerve through its ear branch and thus realizes the impact on the brain. The neuro-hemodynamic effects of the mantra "OM" have not yet been studied.

Materials and Methods: Neuro-hemodynamic effects of mantra 'OM' were studied in nine healthy men and three right-handed women (n = 12) using functional magnetic resonance imaging (fMRI). The effects after chanting the mantra "OM" were compared to pronouncing the sound "ssss". The analysis was performed using Statistical Parametric Image 5 (SPI5).

Results : In this study, during the chanting of the mantra "OM", a significant deactivation (changes in brain activity compared to the resting state) was observed in different parts of the brain : orbito-frontal, cingulate cortex anterior, parahippocampal gyrus, hippocampus, and thalamus. 

The right cerebellar amygdala also showed a significant decrease in activity.  

During the chanting of the mantra "OM" no significant activation was observed. And when pronouncing the sound "ssss", on the contrary, neither activation nor deactivation occurred in these parts of the brain.

Conclusion : The neuro-hemodynamic effects of mantra chanting "OM" testify to limbic deactivation. Since similar observations have been reported under the action of the vagus nerve, which is used to treat depression and epilepsy, the study results suggest a potential role for chanting the 'OM' mantra in clinical practice.

Introduction

Vagus nerve stimulation is used in the treatment of depression, and epilepsy. Studies with positron emission tomography (PET) [3] have shown a reduction in blood flow in the limbic area of the brain during the line of electrical stimulation of the vagus nerve. Other studies using functional magnetic resonance imaging [4] have shown prominent limbic areas outside the brain during vagus nerve stimulation through the skin. In this procedure, an electrical impulse acts inside the left tragus - and thus the ear branch of the vagus nerve.

It is widely known to use the mantra "OM" in meditation practices [5]. Chanting the mantra "OM" creates a feeling of vibration around the ears. It is also considered that these sensations associated with the transmission of impulses through the intermediate branch of the ear to the vagus nerve. We hypothesized that chanting "OM" will cause similar neuro-hemodynamic effects off the limbic areas of the brain, amygdala, hippocampus, parahippocampal, thalamus, orbitofrontal and anterior cingulate cortex, as revealed it in the previous study [5].

Materials and methods

The study involved nine healthy, right-handed men and three women (n=12), who agreed to enter the MRI study as participants. Two qualified psychiatrists independently evaluated these volunteers to prevent: 1) psychiatric diagnoses, 2) family history of serious mental illness in the first generation, 3) pregnancy or postpartum condition 4) substance abuse or addiction , 5) severe neurological disorder, 6) any contraindication to MRI, 7) clumsiness. 

The absence of psychiatric illnesses was established thanks to a special MINI survey (Mini international neuro-psychiatric interview plus) [5]. The age range of the subjects was 22-39 years (mean ± SD = 28 ± 6 years). All participants had an education. Four of the study participants underwent formal yoga training, including meditation, for the rest this technique was new. The study protocol was verified by the ethics committee of the National Institute of Mental Health and Neurology. In addition to the consent for the current study, which has already been given by the subjects, they received the results of the current FMRT, and were taught to chant the mantra OM before proceeding with the new FMRT survey.

Participants were trained to chant the mantra "OM" with an experienced yoga teacher. An important condition is the absence of fatigue and breaks. The vowel "O" sang for 5 seconds, and for another 10 seconds - the consonant "M" . In the electro-physiological studies conducted earlier, the mental chanting of the mantra "OM" was used, in this study the chanting of the mantra was chosen aloud. This provided objective confirmation of task accomplishment during FFMT, as well as ensuring vibration sensitivity and vagus nerve stimulation through the ear canals. 

The state of control was the reproduction of the sound "  ssss  »  for the same duration (15 seconds). The sound "ssss" was chosen for comparison with the exhalation while chanting the mantra "OM", but without the sensation of vibration around the ears. Both practices were performed in the supine position. Similarly, all study participants were familiar with performing the task in the MRI tube.

At the end of the mission, one of the researchers established that the subjects felt the vibration only during the chanting of "OM", but not with the sound "  ssss  »  .

The FFMT procedure consisted of several blocks. The steps of the experiment: 1) first a high-resolution structural study of the brain 2) followed by a series of echoplane imaging (EPO), in which the level of oxygen in the blood was analyzed . Echoplane imaging was repeated every 3 seconds. Within 10 minutes, 200 EPO exams were performed. These 10 minutes were made up of "OM" and "sss" blocks of 15 seconds. These blocks were mixed with 15 second rest periods. In total there were 10 OM blocks, 10"  ssss  and 20 rest blocks [Figure 1].

Figure 1. 1 cycle: "Rest-"OM"-Rest-"sss", 10 cycles were performed by each subject during the FFRI test.