Meditation, Slow Wave Sleep, and Ecstatic Seizures
SHORT DESCRIPTION (25 words):
A description and analysis of phosphene images suggests that the EEG patterns of advanced meditators and healers may be generated by slow wave sleep rhythms.
LONG DESCRIPTION (580 words):
Electroencephalographic studies of advanced meditators and healers report three types of cortical EEG patterns: (1) high-amplitude occipital alpha which, unlike normal waking alpha, is not blocked by sensory stimulation;
(2) theta-delta predominant in the frontal and central leads with occipital alpha occupying less than half of the epoch, as in stage 1 NREMS; and, (3) a sudden shift from the theta-delta patterns to lower delta frequencies, followed by a second shift to high-voltage beta and gamma surges at the vertex or over the temporal lobes. Little is known about the kinds of neural mechanisms that generate these unusual EEG patterns. This presentation proposes a new hypothesis about the neural mechanisms involved based on an analysis of phosphene images. The presenter will describe two sets of phosphene images, one he often observes at sleep onset or early in meditation, another he observed on one occasion when his attempt to meditate in the early morning hours while in a sleep-deprived condition had dramatic and memorable consequences. The phosphene images described here parallel descriptions of light visions described in the ancient Vedic scriptures and in yoga meditation texts in the Hindu and Tibetan Buddhist religious traditions. In modern contexts, these lights are often referred to as 'cakras' that manifest the progress of 'kundalini energy' moving through a subtle body. Based on an analysis of the spatiotemporal characteristics of the phosphene images, the presenter suggests that the phosphenes represent the activation of sleep rhythm oscillators in the thalamus: (1) the threshold images are annuli that appear at intervals similar to the synchronous spindle bursts fired by the thalamic reticular nucleus (RTN) and have shapes that reflect rebound bursts fired by thalamocortical (TC) cells in the visual relay of the thalamus, the lateral geniculate nucleus (LGN), after the release of spindle wave inhibition; and (2) images of expanding waves of amorphous, mist-like phosphene match what is known about the propagation patterns of the cortical slow (< 1 Hz) waves that interact with TC cells to generate delta activity in corticothalamic circuits.
The presentation describes how phosphene images associated with states of calm concentration evolve into a different set of images associated with paroxysmal experience. These paroxysmal phosphenes match descriptions in yoga meditation texts of the light images that signify the final stages of kundalini rising and then its culmination in blissful consciousness of union with the cosmic light. Based on analysis of the spatiotemporal characteristics of this second set of phosphenes, the presenter suggests that the paroxysmal symptoms are generated by the following mechanisms: (1) destabilization of the RTN spindle oscillators, manifested by a shift in timing from spike bursts fired at 0.2 Hz intervals to > 2.0 Hz intervals; (2) emergence of hypersynchronous (spike-and-wave) activity in corticothalamic circuits which does not generalize to the cortical mantle; (3) cortical driving of hypersynchronous activity in the hippocampus (H); (4) outbreak of paroxysmal discharges in the contralateral H, triggering the onset of a bilateral mesotemporal seizure. This experience can be classified as a simple partial seizure because consciousness was not significantly impaired and no amnesia occurred. Studies of EEG patterns associated with simple partial seizures show resemblances to the pattern reported in advanced meditators and healers where there is a shift to low delta, then a second shift to beta and gamma surges at the vertex or over the temporal lobes. If this analysis is correct, it suggests a need to reconsider the health implications of those kinds of meditation techniques that purport to be specifically designed to induce ecstatic visions.