Long-term meditators self-induce high-amplitude gamma synchrony during mental practice

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. Little is known about this process and its impact on the brain. Here we find that long-term Buddhist practitioners self-induce sustained electroencephalographic high-amplitude gamma-band oscillations and phase-synchrony during meditation. These electroencephalogram patterns differ from those of controls, in particular over lateral frontoparietal electrodes. 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. This difference increases sharply during meditation over most of the scalp electrodes and remains higher than the initial baseline in the postmeditation baseline. These data suggest that mental training involves temporal integrative mechanisms and may induce short-term and long-term neural changes. electroencephalogram synchrony | gamma activity | meditationLittle is known about the process of meditation and its impact on the brain (1, 2). Previous studies show the general role of neural synchrony, in particular in the gamma-band frequencies (25-70Hz), in mental processes such as attention, working-memory, learning, or conscious perception (3-7). Such synchronizations of oscillatory neural discharges are thought to play a crucial role in the constitution of transient networks that integrate distributed neural processes into highly ordered cognitive and affective functions (8, 9) and could induce synaptic changes (10, 11). Neural synchrony thus appears as a promising mechanism for the study of brain processes underlining mental training.