All those who have since practiced meditation in a secular or religious way, this training of the mind, testify to its virtues, in particular to detach themselves from the suffering and the feeling of dissatisfaction, inherent in the human species. But how does meditation affect the brain? The question fascinates researchers whose most successful studies began only in the 2000s, with the appearance of brain imaging technologies. This work on "contemplative neuroscience" demonstrates that our brain can be trained and physically modified in a spectacular way, confirming the incredible intuition of Siddhartha. But, to what extent? A handful of scientists, including the pioneers, Francisco Varela and Richard Davidson, founders in Massachusetts (USA) of the Mind and Life Institute (Spirit and Life) in 1987, with the collaboration of the XNUMXth Dalai Lama, shed light on the matter. They identified three areas of brain activation in the meditator: those that control our attention, our emotions and our presence in the world and to others.
Attention skills sharpen
Almost half of our time (47%) our thoughts wander, increasing activity in an area of our brain called the default mode network. However, we declare ourselves less happy when we summon our memories or think about the future than when we are concentrated on a task. This is the finding of a survey conducted by Harvard psychologists, among 15 people, via a Track Your Hapiness application and cited in the book by science journalist James Kingsland, Buddha in the Age of Neuroscience (Dunod, 2016).
Like virtuoso musicians who, with practice, seem to play without difficulty, the best meditators need less effort to achieve great concentration.
Focused attention meditation invites us to break away from the flow of routine thoughts by focusing our mind on the present moment. What happens when meditators focus on their breathing, for example? Researchers from Emory University in the United States, observing on a scanner – via functional magnetic resonance imaging – the brains of volunteers, identified, during the concentration phase, an activation of neural networks in a region located in back of the forehead, the dorsolateral prefrontal cortex. The more experienced the meditator, the more intense the brain activity in this area of the brain related to attention. This was demonstrated by Richard Davidson and his teams in the University of Wisconsin laboratory, comparing novices to meditators with at least 10 hours of practice – the equivalent of a three-year Buddhist retreat. . Remarkably, the curve of intensity is reversed for the most seasoned of them, underlining that the best meditators need less effort to achieve great concentration. A bit like virtuoso musicians who, with practice, seem to play without difficulty.
More gray matter
Another experiment, conducted in the same laboratory by Heleen Slagter, this time showed the virtues on the attention of the second type of meditation, that of Mindfulness, where the mind is open to all sensations, remaining calm and relaxed. The subjects had to detect on a screen among a sequence of letters, two numbers appearing 300 milliseconds apart, which is almost impossible for a normal brain, limited by a phenomenon called attentional blinking. However, after three months of intensive retreat, the meditators perceived the two numbers more often than the control subjects. This improvement was reflected in them by a decrease in the intensity of a particular cerebral wave, the P3b wave. “By dint of practice, the very structure of the brain changes,” adds Antoine Lutz, research fellow at the Lyon Neuroscience Research Center. The brain tissue of the prefrontal cortex involved in the processing of attention thickens, to the point of compensating in the most assiduous meditators for the loss of gray matter due to aging.
Emotional regulation improves
For Buddhists, our mind creates “dukkha”, or suffering. And meditation is a way to let go. It would also have virtues on our relationship to pain. Teams of researchers including that of the Wake Forest University School of Medicine in North Carolina have used a device that intermittently causes brief pain on patients trained in Mindfulness and on novices, while a scanner records activation of brain areas. They observed in meditators a significant reduction in pain discomfort, but also in its intensity. These feelings were associated in their brain with distinct regions. Thus the reduction in discomfort was linked to an increase in the activity of the orbifrontal cortex, involved in the management of sensory data. For its part, the decrease in the intensity of the pain correlated with an increase in the activity of the insula, seat of our internal bodily sensations and of the anterior cingulate cortex (ACC), which plays an essential role in the perception of pain. "These brain changes," James Kingsland tells us, "correspond very precisely to the two components of mindfulness meditation: focused attention and open monitoring." The first makes it possible to free oneself from the anxiety linked to the uncertainty of the arrival of the electric shock; the second puts us in a totally neutral attitude of acceptance. In the most experienced meditators, there is even a shrinkage of the amygdala, a brain area involved in the processing of fear.
A more intense presence in the world
Still other studies have looked at the practice of compassion, the most advanced form of Buddhist meditation. Richard Davidson and his colleagues at the University of Wisconsin placed electrodes on the scalps of eight experienced Tibetan monks during such a compassionate meditation session. Electroencephalography revealed intense production of gamma rhythms in their brains. These high amplitude oscillations, never observed before in healthy individuals, are the sign of a significant synchronization of neuronal activity between different areas of the brain. If they have not yet revealed all their secrets, they could reflect a better awareness of oneself and of the environment. As if, approaching enlightenment, these monks lived a more intense experience of the world
Français
Français
English