Although it was not possible to blind participants as to the arm in which they were enrolled, the vacation arm nevertheless affords the possibility of helping tease apart a vacation effect from a meditation effect.
We constructed classifiers to distinguish between the baseline and post-intervention states (Supplementary Methods) and achieved prediction accuracies of 96% for the vacation effect (area under the receiver operating characteristic curve, or AUROC, equal to 0.98) and 85% for the meditation effect (AUROC=0.93; Supplementary Figure S1), supporting the potential for blood-based wellness biomarkers.
To assess the predictive power of the GE changes between the groups, we employed machine-learning procedures to construct classifiers to predict group membership based on pre- versus post-intervention GE (vacation effect) and regular versus non-regular post-intervention GE data (meditation effect).
The absence of a comparison or control state or group is an obvious disadvantage, as the effect of time during a session can be expected to influence the evoked potential components and the meditation effect would not be separated from this.
Lutz, A., Brefczynski-Lewis, J., Johnstone, T. & Davidson, R. J. Regulation of the neural circuitry of emotion by compassion meditation: effects of meditative expertise.
Identifying network structures in a blood Bayesian network reflecting vacation and meditation effects.
Luders, E., Kurth, F., Toga, A. W., Narr, K. L. & Gaser, C. Meditation effects within the hippocampal complex revealed by voxel-based morphometry and cytoarchitectonic probabilistic mapping.
Lippelt, D. P., Hommel, B. & Colzato, L. S. Focused attention, open monitoring and loving kindness meditation: effects on attention, conflict monitoring, and creativity — a review.
To further characterize the structure of the molecular networks associated with the vacation and meditation effects, we projected the modules indicated in Figure 2 on a probabilistic causal network (Bayesian network)30, 31, 32, 33 constructed from a larger independent blood GE study in which hundreds of individuals were GE-profiled and genotyped (Supplementary Appendix).
Our results strongly support the existence of a dedicate brain network that supports the general aspects of meditation effects.
Evidence from a recent meta-analysis of ten neuroimaging studies [ 57] seems to suggest that the caudate body, entorhinal cortex, and medial prefrontal cortex have a central role in supporting the general aspects of meditation effects.
