Shamanic rituals that involve entering a trance state have been a part of the human experience for thousands of years. But we still know very little about the scientific basis of trances.
A team of investigators that included researchers from the Martinos Center for Biomedical Imaging at Mass General recently conducted MRI scans of 15 shamanic practitioners while they were in a trance state.
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The results showed increased connectivity in parts of the brain involved in internally directed thought and cognitive control, as well as decreased connectivity in the auditory pathways in the brain.
This suggests that the repetitive drum sounds that are often used to induce trance states may help to focus the brain inward by creating a predictable rhythmic sound that is easy for practitioners to tune out. Michael Hove, PhD, of the Martinos Center, is both first and corresponding author of the study.