Cross-sectional and longitudinal study of effects of transcendental meditation practice on interhemispheric frontal asymmetry and frontal coherence.

Two studies investigated frontal alpha lateral asymmetry and frontal interhemispheric coherence during eyes-closed rest, Transcendental Meditation (TM) practice, and computerized reaction-time tasks. In the first study, frontal coherence and lateralized asymmetry were higher in 13 TM subjects than in 12 controls. In the second study (N = 14), a one-year longitudinal study, lateral asymmetry did not change in any condition. In contrast, frontal coherence increased linearly during computer tasks and eyes-closed rest, and as a step-function during TM practice--rising to a high level after 2-months TM practice. Coherence was more sensitive than lateral asymmetry to effects of TM practice on brain functioning.