The dependent variable was the average gamma activity (25-42 Hz) in each ROI. To estimate the gamma activity, adjusted for the very high frequencies, we performed a covariance analysis for each region of interest (ROI) for each subject. Thus, the variation through time of the average spectral power in the 80-120 Hz frequency band provided a way to quantify the variations of the muscle contribution to the EEG gamma activity through time. The muscle EEG signature is characterized by a broad-band spectrum profile (8-150 Hz) peaking at 70-80 Hz ( 16). Here we assume that the spectral emission between 80 and 120 Hz provided an adequate measure of the muscle activity ( 14, 15). During the neutral states, all of the subjects were asked to be in a nonmeditative, relaxed state.ĭespite careful visual examination, the electroencephalographic spectral analysis was hampered by the possible contamination of brain signals by muscle activity. During the EEG data collection period, both controls and long-term practitioners tried to generate this nonreferential state of loving-kindness and compassion. After some training, the subjects were asked to generate such feeling toward all sentient beings without thinking specifically about anyone in particular. During the training session, the control subjects were asked to think of someone they care about, such as their parents or beloved, and to let their mind be invaded by a feeling of love or compassion (by imagining a sad situation and wishing freedom from suffering and well being for those involved) toward these persons. The quality of their training was verbally assessed before EEG collection. A week before the collection of the data, meditative instructions were given to the control subjects, who were asked to practice daily for 1 h.

Because “benevolence and compassion pervades the mind as a way of being,” this state is called “pure compassion” or “nonreferential compassion” ( dmigs med snying rje in Tibetan). The state of unconditional loving-kindness and compassion is described as an “unrestricted readiness and availability to help living beings.” This practice does not require concentration on particular objects, memories, or images, although in other meditations that are also part of their long-term training, practitioners focus on particular persons or groups of beings. These data suggest that mental training involves temporal integrative mechanisms and may induce short-term and long-term neural changes. This difference increases sharply during meditation over most of the scalp electrodes and remains higher than the initial baseline in the postmeditation baseline. In addition, the ratio of gamma-band activity (25-42 Hz) to slow oscillatory activity (4-13 Hz) is initially higher in the resting baseline before meditation for the practitioners than the controls over medial frontoparietal electrodes. These electroencephalogram patterns differ from those of controls, in particular over lateral frontoparietal electrodes. Here we find that long-term Buddhist practitioners self-induce sustained electroencephalographic high-amplitude gamma-band oscillations and phase-synchrony during meditation. Little is known about this process and its impact on the brain. Practitioners understand “meditation,” or mental training, to be a process of familiarization with one's own mental life leading to long-lasting changes in cognition and emotion.

Research site gamma control