What happens in the brain of meditators when perception changes but not the stimulus?

Jürgen Kornmeier,Stefan Schmidt,Lukas Hecker,Marc Wittmann,Evelyn. Friedel,Guido Hesselmann

doi:10.1371/journal.pone.0223843

Abstract

During the observation of an ambiguous figure our perception alternates between mutually exclusive interpretations, although the stimulus itself remains unchanged. The rate of these endogenous reversals has been discussed as reflecting basic aspects of endogenous brain dynamics. Recent evidence indicates that extensive meditation practice evokes long-term functional and anatomic changes in the brain, also affecting the endogenous brain dynamics. As one of several consequences the rate of perceptual reversals during ambiguous figure perception decreases. In the present study we compared EEG-correlates of endogenous reversals of ambiguous figures between meditators and non-meditating controls in order to better understand timing and brain locations of this altered endogenous brain dynamics. A well-established EEG paradigm was used to measure the neural processes underlying endogenous perceptual reversals of ambiguous figures with high temporal precision. We compared reversal-related ERPs between experienced meditators and non-meditating controls. For both groups we found highly similar chains of reversal-related ERPs, starting early in visual areas, therewith replicating previous findings from the literature. Meditators, however, showed an additional frontal ERP signature already 160 ms after stimulus onset (Frontal Negativity). We interpret the additional, meditation-specific ERP results as evidence that extensive meditation practice provides control of frontal brain areas over early sensory processing steps. This may allow meditators to overcome phylogenetically evolved perceptual and attentional processing automatisms.

Highlights

During observation of an ambiguous figure, like the famous Necker cube [1], our perception becomes unstable and reverses spontaneously between mutually exclusive interpretations (Fig 1)
The third regions of interest (ROIs) was related to the Parietal and Frontopolar Positivities and was restricted to the electrodes Pz, Cz and Fpz and to a time window from 250 ms to 700 ms after stimulus onset. Within this ROI we identified amplitude and latency of the maximal positive deflection from the difference ERPs (dERPs) relative to the baseline
In an additional exploratory analysis we looked for further deflections in the grand mean dERP traces outside the spatio-temporal ROIs with significant deviations from zero with a pvalue below a pre-defined alpha value of 0.01 for at least 10 data points (i.e. 20 ms) in at least two neighboring electrodes

Summary

Introduction

During observation of an ambiguous figure, like the famous Necker cube [1], our perception becomes unstable and reverses spontaneously between mutually exclusive interpretations (Fig 1). We can volitionally control this perceptual dynamics to some degree but we cannot prevent. What happens in the brain of meditators during perceptual reversals. Freiburg in the funding programme Open Access Publishing. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Discussion

Conclusion