Autonomic and EEG patterns during eyes-closed rest and transcendental meditation (TM) practice: The basis for a neural model of TM practice

In this single-blind within-subject study, autonomic and EEG variables were compared during 10-min, order-balanced eyes-closed rest and Transcendental Meditation (TM) sessions. TM sessions were distinguished by (1) lower brea th rates, (2) lower skin conductance levels, (3) higher respiratory sinus a rrhythmia levels, and (4) higher alpha anterior-posterior and frontal EEG c oherence. Alpha power was not significantly different between conditions. T hese results were seen in the first minute and were maintained throughout t he 10-min sessions. TM practice appears to (1) lead to a state fundamentall y different than eyes-closed rest; (2) result in a cascade of events in the central and autonomic nervous systems, leading to a rapid change in state (within a minute) that was maintained throughout the TM session; and (3) be best distinguished from other conditions through autonomic and EEG alpha c oherence patterns rather than alpha power. Two neural networks that may med iate these effects are suggested. The rapid shift in physiological function ing within the first minute might be mediated by a "neural switch" in prefr ontal areas inhibiting activity in specific and nonspecific thalamocortical circuits. The resulting "restfully alert" state might be sustained by a ba sal ganglia-corticothalamic threshold regulation mechanism automatically ma intaining lower levels of cortical excitability. (C) 1999 Academic Press.