Preliminary functional magnetic resonance imaging Stroop task results before and after a Zen meditation retreat

Abstract

FOR MANY CENTURIES, Asian philosophers have affirmed that there are different states of awareness to be developed through meditation.1 Meditation results in changes in cognition, sensory perception, affect, hormones, and autonomic activity. Until today, there have been very few imaging studies of the neural correlates of meditation. Most of them study the act of meditation by experienced meditators during image acquisition. Functional magnetic resonance imaging (fMRI) has the ability to collect anatomical and functional data and has better resolution compared to positron emission tomography and single photon emission computed tomography. The intense noise of the machine and the obligatory prone position are not the best environment for the study of meditation practice in the MR machine.2 Meditation involves sustained focused attention that can be developed by training.2–5 Instead of evaluating the meditation practice itself, our approach is to evaluate the neural correlates of performance modulation on an attention paradigm (the Stroop word–color task; SWCT) before and after a meditation retreat. The SWCT relies on the inhibition of reading colored words, a process that tends to dominate and occur earlier than the color recognition process. Color naming can be slowed by the concomitant presence of an incongruent word color. For example, naming ‘blue’ as the color of the word ‘red’ is slower than naming the word ‘blue’ displayed in blue color.6 In this study we examined the short-term effects of an 8-day long Zen Buddhist meditation retreat (‘Sesshin’) on the performance in the SWCT with fMRI6 as a feasibility study with a well-known neuropsychological paradigm using a 1.5-T magnet (Signa Twin; Excite V. 10, GE Medical Systems, Milwaukee and EUA, gradient 40 mT/m, and an eight channel head coil). Silicon earplugs and earphones were provided to attenuate acoustic noise. One Zen Buddhist nun and four other regular meditators with at least 6 months of meditation practice were scanned before and after ‘Sesshin’, twice in each session (test–retest design). The subjects gave their written consent, according to the Hospital Israelita Albert Einstein Ethics Committee. The fMRI results of subject C00040 (as a representative of the entire group) shows enhanced activation of the anterior cingulate, right dorsolateral prefrontal, insular, occipital and parietal cortices after meditation practice. According to the literature these areas represent functional activation related to attentional circuitry2–5 and reinforce the idea that meditation can further develop attentional abilities that have lasting effects. The small number of subjects does not allow for statistical validation of the results, but the change in each subject compared to the individual's baseline and the improved performance does encourage us to pursue this experiment design. This new model of investigation is based on studying the effects of meditation while subjects perform neuropsychological paradigms, instead of having them practice meditation within the MR magnet. The authors thank the Instituto Israelita de Ensino e Pesquisa (IIEP) – Hospital Israelita Albert Einstein (HIAE) for the financial support, Ricardo Vêncio for pre-analysis, Liana Guerra Sanchez and Claudia Santana for assistance in data collection, and Comunidade Zen Budista and Coen Sensei for the volunteers.