مقایسه انسجام، دامنه و الگوهای eLORETA در طول مدیتیشن متعالیه و عمل TM-Sidhi
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|31819||2011||5 صفحه PDF||سفارش دهید||3907 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : International Journal of Psychophysiology, Volume 81, Issue 3, September 2011, Pages 198–202
This random-assignment study compared coherence, amplitude, and eLORETA patterns during practice of the Transcendental Meditation (TM) and the TM-Sidhi programs. The TM technique involves systematic transcending of contents of experience to a state of pure consciousness. The TM-Sidhi program involves sanyama—the simultaneous experience of dhārānā (fixity), dhyāna (transcending) and samādhi (pure consciousness). Thirty-two channel EEG was recorded from experienced TM subjects randomly assigned to two consecutive 10-min TM sessions or to a 10-min TM session followed by 10-min TM-Sidhi practice. Compared to TM practice, TM-Sidhi practice was characterized by higher frontal alpha1 and beta1 amplitudes, and eLORETA-identified sources of alpha1 EEG in right-hemisphere object recognition areas including the right parahippocampus gyrus, right fusiform gyrus, lingual gyrus, and inferior and medial temporal cortices. These cortical areas are involved in specific/holistic representation of words. The observed brain patterns support the descriptions of sanyama as including both specificity (sutras or verses), as suggested by higher frontal beta1 EEG amplitude and by eLORETA sources in right-hemisphere object-recognition areas, and holistic experience (pure consciousness) as suggested by higher frontal alpha1 EEG amplitude. These EEG patterns fit the complex description of sanyama.
Research has described two features of consciousness: the level of consciousness (graded levels of being awake or asleep), and the contents of consciousness (inner thoughts, feelings, and perception of outer objects) ( Koch and Tsuchiya, 2007 and Tsuchiya and Adolphs, 2007). These two features of consciousness are intertwined during ordinary waking experiences. Consequently, most scientists beginning with William James concluded that consciousness cannot be experienced without an object ( James, 1890/1951 and Natsoulas, 1997). However, these two features of consciousness can be separated during meditation practices, allowing exploration of conscious contents and levels of consciousness. Three meditation categories have been described that are distinguished by cognitive processes and EEG patterns (Travis and Shear, 2010). The first two categories, Focused Attention and Open Monitoring, include both contents of consciousness and levels of consciousness. In Focused Attention meditations, the level of consciousness is intertwined with contents—the object of sustained focus completely fills awareness. In Open Monitoring meditations, the level of consciousness begins to be separated (mindful) from changing contents, objects of experience such as body states, thoughts, feelings or breath. The third category, Automatic Self-Transcending, includes meditations designed to transcend the procedures of the meditation. These techniques minimize the contents of consciousness and so allow exploration of levels of consciousness devoid of content. The Transcendental Meditation™ (TM™) technique is in the third category of meditations. TM practice is a process of transcending, which involves appreciating a mantra at “finer” levels in which the mantra becomes increasingly secondary in experience and ultimately disappears, while self-awareness becomes more primary (Maharishi Mahesh Yogi, 1969 and Travis and Pearson, 2000). This state is described as “pure consciousness” in which consciousness is open to itself (Maharishi Mahesh Yogi, 1994). TM practice has been characterized by 1) EEG patterns—higher frontal and central alpha power (Banquet, 1973, Dillbeck and Bronson, 1981, Hebert et al., 2005 and Travis and Wallace, 1999), and higher frontal alpha coherence (Dillbeck and Bronson, 1981, Gaylord et al., 1989, Levine, 1976 and Travis and Arenander, 2006; Travis et al.; Travis et al., 2000); 2) physiological patterns—lower breath rate, lower skin conductance and lower plasma lactate (Dillbeck and Orme-Johnson, 1987); 3) MEG patterns—source localization of MEG activity in medial prefrontal and anterior cingulate cortices (Yamamoto et al., 2006); 4) eLORETA source localization—sources of alpha1 activity in midline frontal and parietal cortices that are part of the default mode network (Travis et al., 2010); and 5) patterns of cerebral metabolic rate in a pilot PET study—higher frontal and parietal activity and lower thalamic activity, compared to eyes-closed rest (Newberg et al., 2006). While TM practice has been extensively investigated, no studies have compared brain patterns during TM with those during the advanced TM program, the TM-Sidhi program. The TM technique involves transcending; in contrast, the TM-Sidhi program involves sanyama—the simultaneous processes of dhārānā (fixity), dhyāna (transcending) and samādhi (pure consciousness) ( Maharishi Mahesh Yogi, 1978). (The TM-Sidhi program is described in more detail below in the procedure.) Since TM-Sidhi practice involves both changing objects of attention (dhārānā), transcending (dhyāna), and the experience of pure consciousness (samādhi) then, compared to TM practice, one might expect heightened alpha1 activity characteristic of Automatic Self-Transcending and heightened beta1 activity characteristic of active processing, during TM-Sidhi practice. This random-assignment study compared EEG amplitude and coherence during Transcendental Meditation and TM-Sidhi practice in theta2 through gamma frequency bands. It also investigated eLORETA patterns during these two practices. eLORETA was developed at the KEY Institute for Brain-Mind Research at the University of Zurich (Pascual-Marqui et al., 1994) to compute the 3-D intracerebral distribution of sources of scalp-recorded electrical potentials (Pascual-Marqui, 2002). Two refinements of this method have been released: first, sLORETA (standardized Low Resolution Electromagnetic Tomography), which uses standardized current density to calculate intracerebral generators, and recently eLORETA (exact Low Resolution Electromagnetic Tomography), which does not require standardization for correct localization (Pascual-Marqui, 2002 and Pascual-Marqui, 2007). Both sLORETA and eLORETA are argued to have low resolution but zero localization error even in the presence of measurement and biological noise (Pascual-Marqui, 2007). The current implementations of sLORETA and eLORETA use a realistic head model calculated by Fuchs et al. (2002), and electrode coordinates provided by Jurcak et al. (2007). The hypothesis tested in this study was that compared to TM practice, TM-Sidhi practice would be characterized by higher levels of alpha1 and beta1 amplitude and coherence. No predictions were made about eLORETA sources, since only one paper has reported results from eLORETA during TM practice.