Meditation reduces stress in the brain

by Svend Davanger, MD PhD

People have been meditating for thousands of years. During the last decade, researchers have obtained a better understanding of what goes on in the brain during meditation.

The impact of meditation on the meditator’s heart rhythm, blood pressure and hormone level has been known for many years. Recent technological developments are beginning to provide answers about what goes on in the brain during meditation.

For the last 15 years or so, new ways of applying MRI have made it possible to register and observe activity in the brain while it is consciously used for various tasks, including meditation.
These recent developments in neurological research indicate that meditation may actually change parts of the brain’s reactivity to stress.

Ego functions and the prefrontal cortex

Scientists have particularly studied an area in the front of the brain called the prefrontal cortex, which is associated with personal traits. Characteristic types of behaviour are based on functional patterns in the prefrontal cortex. Research has shown that this is one of the areas of the brain that is typically activated during meditation.

Damage to the prefrontal cortex may change what psychologists call our ego functions, i.e., our ability to make decisions, regulate emotions, and to understand and control our attention, reactions and impulses. The prefrontal cortex does not directly determine what we do, but collects information, processes it, puts it together, and analyses it in order to facilitate decision-making. Meditation activates this area.

Alpha waves and theta waves

One way of measuring activity in the brain is by observing electrical brain waves. We distinguish between delta, theta, alpha, beta and gamma frequencies. None of the frequencies is peculiar to meditation, but we know that alpha frequency increases in the posterior parts of the brain during meditation, indicating that we use our senses less while we meditate. Furthermore, increased theta activity in frontal brain regions during meditation may be due to relaxation in areas associated with stress and emotions.

Theta waves seem to be strongest in the prefrontal cortex during meditation. So far we do not know much about what this actually means, but the finding is still significant. Since the brain governs our capacity for awareness and attention, meditation cannot be described as a passive, trance-like state. The brain remains active during meditation.

How the brain produces relaxation

We know that when we use our brain during meditation, blood pressure and heart rate decrease. An interesting question is which neural mechanisms allow our thoughts to influence heart rate. How can a cognitive activity like meditation make us more relaxed?

The answer may be found near the frontal midline of the brain, in the anterior cingulated cortex, a neural area associated with attention and emotions. This area influences the autonomous functions of our body, e.g., heart, lung and intestine activity. Japanese researchers have measured the brain’s frequency (EEG) and the heart’s frequency (EKG) during meditation. They have found that whenever meditation strengthens theta waves in the anterior cingulated cortex, changes occur in the heart rate that are typical of relaxation. It seems that by increasing theta waves in the anterior cingulated cortex meditation produces a relaxation in our heart function.

The brain wave patterns of meditation are different from those observed in sleep, where we switch between delta activity (in deep sleep phases) and theta activity. Meditation takes place while we are awake. This means we are able to exercise conscious control over our mental actions, which is not the case when we are asleep.

Training the brain

One important question is how meditation governs the brain. It is likely that within a few years research will have documented how the brain changes over time with regular meditation.
Early findings in this field were presented at a major recent brain conference in Washington, DC. According to this research, meditation seems to strengthen the cerebral cortex in areas involved in emotional control. This is in line with meditators’ frequent reports of an increased capacity to cope calmly with emotional strain.

Several American researchers describe meditation as a complex training of the brain. Personally, however, I believe that meditation is most effective when practitioners do not experience it as difficult. Some research findings indicate that techniques performed without effort produce the best results and the deepest relaxation. If meditation is demanding, its greatest potential benefits may be lost. Practising meditation may be an important training activity for the brain, but it should be less arduous than physical exercise and training for competitive performance.

Svend Davanger, MD PhD, is Associate Professor at the University of Oslo and has been an Acem instructor since 1981. He is one of the editors of the book Fighting Stress: Reviews of Meditation Research (Oslo: Acem Publishing 2008) and has published popular articles on brain activity during stress and meditation. His main research publications are within neuroscience.

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