Authors: Kieran C.R. Fox, Savannah Nijeboer, Matthew L. Dixon, James L. Floman,
Melissa Ellamil, Samuel P. Rumak, Peter Sedlmeier, Kalina Christoff
Title: Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuroimaging in meditation practitioners
Summary: Like almost every contemplative scientist will point out, our understanding of what meditation can do for us in its infancy. However, this investigation sets out the progress made in understanding meditation related to structural changes in the brain. The researcher identified 21 studies that imaged the brains of meditators, looking for structural changes. Although most of the research was cross-sectional in nature some ‘before and after’ examples are included.
This project reviewed research that used any of the six leading measures of structural changes in the brain (volumetry, concentration, thickness, fractional anisotropy (FA), diffusivity (axial and radial) and gyrification). The selected papers were qualitatively reviewed and also subject to an anatomical likelihood estimation (ALE) meta-analysis. Qualitative results highlighted nine brain areas that might have undergone structural alteration as a result of meditation practice. Seven areas of grey matter: anterior/mid-cingulate cortex, fusiform gyrus, hippocampus, inferior temporal gyrus, insular cortex, rostrolateral prefrontal cortex, somatomotor cortices and two white matter pathways: corpus callosum, superior longitudinal fasciculus.
Although Lazer et al. made efforts to link the results of morphometric neuroimaging to a range of functional studies there are a number of problems in this approach. There is little structure in how meditators and meditation methods are grouped together, both in creating the meta-analysis and explanations for alterations in brain structures. This in part reflects the limitations of the 21 neuroimaging studies used, it is also linked to the widely documented problems in the theoretical frameworks used by contemplative science. For example, common features are looked for in diverse experiments using different forms of meditation, both secular and spiritual. Although the participants from the experimental groups cited in the studies had all meditated, they often differ significantly in the methods they use, frequency and duration of practice and time spent in intensive meditation retreat.
Despite the limitations, which are in large part symptomatic of meditation research in general, this remains an influential study fo0r both cognitive psychology and neuroscience.