ABSTRACT
Yogis practising Raj Yoga claim that during samadhi they are oblivious to 'external' and 'internal' environmental stimuli although their higher nervous activity remains in a state of 'ecstasy'. In both the Yogis who were exposed to 'external' stimulation, all the stimuli blocked the alpha rhythm and changed it to a low voltage fast activity when the Yogis were not meditating. The electroencephalogram records of these two Yogis showed persistent- alpha activity, both before and during the period in which the hand was immersed in cold water. Yogis generally claim that during samadhi they are oblivious to their external and internal environments, and in the present experiments their alpha rhythm could not be blocked by external stimuli. 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.
