Some aspects of electroencephalographic studies in Yogis

Abstract Four Yogis who practised samadhi were investigated electroencephalographically. It was observed that their resting records showed persistent alpha activity with increased amplitude modulation during samadhi. The alpha activity could not be blocked by various sensory stimuli during meditation. Two Yogis, who could keep their hand immersed in ice cold water for 45–55 min, also showed persistent alpha activity both before and during this practice. The possible mechanism of these observation has been discussed.