Electroencephalographic, Cognitive and Autonomic Correlates of States of Concentrative Meditation

Author: Dylan DeLosAngeles

DeLosAngeles, Dylan, 2010 Electroencephalographic, Cognitive and Autonomic Correlates of States of Concentrative Meditation, Flinders University, School of Medicine

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Abstract

Meditation is generally characterised as "a family of complex emotional and attentional regulatory strategies developed for various ends, including the cultivation of well-being and emotional balance" (Lutz et al. 2008). Although specific methods vary, most meditative techniques strive for and report states of mental alertness and focus, as well as simultaneous states of physical and emotional relaxation. This project investigated distinct states or absorptions of Buddhist concentrative meditation as transliterated from traditional texts into clear and comprehensible descriptions and explanations which are amenable to science. The way meditative states and traits are classified and characterised in the scientific literature is appraised, including a discussion on the definitions and technical terms associated with meditation. In addition, an explication of the concentrative meditation technique investigated in this project discusses the cognitive and psychological processes in meditation, descriptions of meditative states and how meditators enter and maintain each state. The history and philosophy of Buddhism is also briefly discussed. After relevant background information is supplied with regard to electroencephalography (EEG), the evidence for the effects of meditation is reviewed. This project involved four experiments which were run in a counterbalanced order during a single day, however each subject came in on a different day. Thirteen meditators and thirteen non-meditator controls were recruited, however due to subject and equipment complications, the number of subjects used in analysis varies between experiments. These details are given in each chapter. Experiment 1: To assess whether concentrative meditation influences early sensory processing and attentional resource allocation, event-related potentials (ERPs) and behavioural responses were recorded from ten meditators and ten pair-matched non-meditator controls during an audiovisual continuous performance task, performed before and after a meditation condition. This task required subjects to respond to audio and/or visual target stimuli interspersed among distractor and non-target stimuli by pressing a button. An improvement in response speed and accuracy in both groups after meditation was interpreted as the ability of both groups to enter a light state of meditation between attention tasks. Consistently larger P2 mean amplitudes were found in meditators, compared to controls, suggesting that extended practice of meditation can influence the long-term capacity to selectively attend. In addition, larger P3 mean amplitudes in occipital electrodes were found in meditators. This result is likely to represent a long-term enhancement of target detection, precipitated by the practice of meditation. Experiment 2: Additionally, five different meditative states were examined using measures of EEG and autonomic activity in twelve meditators and twelve pair-matched non-meditator controls. During the experiment, meditators were found to demonstrate significant changes in theta and gamma EEG activity which intimate enhanced focus and mental quiescence during meditative states. In addition, changes in autonomic activity were indicative of decreased sympathetic tone, in other words physical, mental and emotional relaxation. Experiments 3: The perception of external stimuli during meditation was examined in twelve meditators and twelve pair-matched non-meditator controls. Subjects responded with a button-press when they became aware of an auditory, visual or tactile stimulus. No changes in any group or condition were found that could be interpreted as a significant effect from meditation. Experiment 4: Cortical steady-state responses were recorded from eight meditators and eight pair-matched non-meditator controls during meditation. No changes in any group or condition were found that could be interpreted as a significant effect from meditation. In summary, contributions have been made to the scientific understanding of meditation by providing evidence for the efficacy of meditation to induce states of physical relaxation, mental and emotional calm, enhanced concentration and diminished thought activity.

Keywords: meditation,attention,perception,sensory processing,electroencephalography,EEG,theta,gamma,EMG,event-related potential,ERP,evoked potential,EP,steady-state response,SSR,autonomic function,electrodermal activity,respiration,temperature,blood oxygen saturation,relaxation,state,trait,buddhist,concentration,meditator
Subject: Medicine thesis

Thesis type: Doctor of Philosophy
Completed: 2010
School: School of Medicine
Supervisor: Professor John Willoughby, Dr Graham Williams, Mr John Burston, Dr Kenneth Pope and Professor C. Richard Clark