Changes in p300 following two yoga-based relaxation techniques.

Cyclic meditation (CM) is a technique that combines "stimulating" and "calming" practices, based on a statement in ancient yoga texts suggesting that such a combination may be especially helpful to reach a state of mental equilibrium. The changes in the peak latency and peak amplitude of P300 auditory event-related potentials were studied before and after the practice of cyclic meditation compared to an equal duration of supine rest in 42 volunteers (group mean age +/- SD, 27 +/- 6.3 years), from Fz, Cz, and Pz electrode sites referenced to linked earlobes. The sessions were one day apart and the order was alternated. There was reduction in the peak latencies of P300 after cyclic meditation at Fz, Cz, and Pz compared to the "pre" values. A similar trend of reduction in P300 peak latencies at Fz, Cz, and Pz was also observed after supine rest, compared to the respective "pre" values, although the magnitude of change in each case was less after supine rest compared to after cyclic meditation. The P300 peak amplitudes after CM were higher at Fz, Cz, and Pz sites compared to the "pre" values. In contrast, no significant changes were observed in the P300 peak amplitudes at Fz, Cz, and Pz after supine rest compared to the respective "pre" state. The present results support the idea that "cyclic" meditation enhances cognitive processes underlying the generation of the P300.