Functional magnetic resonance imaging of hippocampal activation during silent mantra meditation.

Moderately experienced meditators with less than two years of practice show significant activation in the hippocampus and parahippocampal formations during silent mantra meditation, as measured by functional magnetic resonance imaging. Activation also occurred in the middle cingulate cortex and precentral cortex, but not in the anterior cingulate cortex, and only small clusters appeared in the prefrontal cortex. The findings suggest that hippocampal activation occurs early in meditation practice and across different meditation styles, including relaxation. The authors propose further research to clarify whether this hippocampal activity relates to memory consolidation.

Study at a glance

Abstract

The objective of the present study was to investigate whether moderately experienced meditators activate hippocampus and the prefrontal cortex during silent mantra meditation, as has been observed in earlier studies on subjects with several years of practice. Subjects with less than 2 years of meditation practice according to the Kundalini yoga or Acem tradition were examined by functional magnetic resonance imaging during silent mantra meditation, using an on-off block design. Whole-brain as well as region-of-interest analyses were performed. The most significant activation was found in the bilateral hippocampus/parahippocampal formations. Other areas with significant activation were the bilateral middle cingulate cortex and the bilateral precentral cortex. No activation in the anterior cingulate cortex was found, and only small activation clusters were observed in the prefrontal cortex. In conclusion, the main finding in this study was the significant activation in the hippocampi, which also has been correlated with meditation in several previous studies on very experienced meditators. We propose that the hippocampus is activated already after moderate meditation practice and also during different modes of meditation, including relaxation. The role of hippocampal activity during meditation should be further clarified in future studies, especially by investigating whether the meditation-correlated hippocampal activity is related to memory consolidation.