Neurophysiologic Correlates to Sensory and Cognitive Processing in Altered States of Consciousness

Research is presented on the altered sensory and cognitive processing as assessed by event-related potential analysis of electroencephalographic data during states of meditation in long-term meditators and due to the effects of psilocybin, a naturally occurring serotonin receptor agonist with hallucinogenic properties. The literature on the neurophysiologic correlates to meditation are reviewed. In a passive auditory oddball paradigm rare tones and distracters are shown to evoke increased sensory processing as indexed by increases in the amplitudes of the N1 and P2 event-related potential components. The distracter stimuli are shown to evoke a later P3a component and increases in frontal theta power associated with attentional engagement. Meditation causes a significant reduction in the P3a amplitude and frontal theta power to distracting stimuli implying the disengagement of attentional networks from ongoing sensory processing.