Dados do Trabalho

Título

Volumetric explanatory analysis in ultra-high-resolution 7T MR brain images in long-term meditators

Descrição sucinta do(s) objetivo(s)

Long-term meditation has been shown to influence gray matter morphometry in several regions. We aim to characterize morphometric changes in experienced connection with spiritual essence meditators whose practice is based on visualization and mantra from the Indian tantric tradition, using for that ultra-high-resolution human brain imaging at 7T.

Material(is) e método(s)

A cross-sectional study was performed in 28 subjects (9 long-term experienced meditators and 19 age-matched healthy controls). T1-weighted images were acquired on a 7T scanner (Siemens Magnetom) and preprocessed using the recon-all pipeline of the FreeSurfer package for deep gray matter (GM) segmentation and cortical parcellation. Additional segmentation of the nuclei of the amygdala and hippocampal substructures was carried out using Freesurfer’s hippocampal subfield module.

Whole brain volume analysis was performed using Freesurfer’s graphical program Query, Design, Estimate, Contrast (QDEC). Mann-Whitney test was done to compare the average volume of the deep GM and white matter (WM) across groups. Finally, group differences in the average volume of 176 region of interest (ROIs) were investigated using the Analysis of Covariance (ANCOVA) test and included intracranial brain volume and age as covariables.

Resultados e discussão

Meditators evidenced significant higher volume in the right anterior aspect of the superior frontal gyrus, rostral middle frontal, pars opercularis of the inferior frontal gyrus, inferior pre-central gyrus, pre-cuneus and paracentral lobule. They also showed higher volumes in the left rostral middle frontal gyrus, insula, postcentral gyrus, supramarginal gyrus, medial superior frontal gyrus, posterior cingulate gyrus and precuneus for the left hemisphere.
Meditators also evidenced higher volume of the right cerebral WM and smaller volumes in the posterior corpus callosum and medial nucleus of the left amygdala, before normalizing by the intracranial volume. After normalization, the only area that evidenced significant volumetric differences across groups was the right CA3-body, higher in the meditators’ group.
Finally, the ANCOVA test showed significant lower volume in the meditators’ group in the left subiculum and medial nucleus of the left amygdala.

Conclusões

These results are in line with earlier studies indicating, when compared to matched controls, that long-term meditators have variations in the volume of the prefrontal cortex, sensory cortices, cingulate cortex, insula, hippocampus, and amygdala.

Palavras Chave

Brain MRI; Meditation; Volumetry

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