The Neural Networks of Meditation, Mind Wandering, and Attention

What is mind wandering?

It is a psychological state that appears spontaneously when there is no specific task to perform. For example: when we look at the landscape or the sky through the window, and we daydream. Mind-wandering therefore occurs when the mind wanders from thoughts focused on a given and present goal to imaginary thoughts about the past or the future. Scientists have created an acronym for this state: REST (Rest) for “Random Episodic Silent Thinking”. This "activity" not perceptible by an outside observer occupies a significant part of our mental life, estimated between a third and a half of our waking time.

Is it positive or negative?

Le mental wandering has positive and negative aspects. This is positive, because it is during these moments of inner journey that the mind imagines, creates, associates ideas or develops projects, and that it revisits the past to improve the future. There are also negative aspects. On the cognitive level, for example, mental wandering reduces our ability to perform a task due to the reduced attention required. It is also a brake and a hindrance to learning. Emotionally, it has been shown that a wandering mind is not a happy mind. In only a third of cases do happy memories return; the rest of the time, neutral or stressful thoughts invade the mind. When this bias predominates, people tend to wander to the same sad memories and use the same brain circuits. This mental rumination, made up of obsessive ideas linked to dark memories of the past, is often charged with negative emotions. It is found in particular in chronic depression and promotes relapses. Another case, post-traumatic stress: the memory of the psychological trauma returns as soon as the mind begins to wander, causing a change in mood.

What happens in our brain depending on whether we are mentally wandering or paying attention?

Mind wandering is the activity of a neural network called the Default Mode Network (DMN). This system was discovered by accident in 2001 by an American neuroscientist, Michael Raichle, and his team. By measuring the activity of a brain that seemed to be at rest, they highlighted the existence of hyperactive zones that consume as much oxygen and energy as when the individual is busy performing a sensory, motor or precise intellectual. They also demonstrated that this network was the support of another function called self-referential processing, or more simply “self-awareness”, “self-reflection” or “self-concern”. Either what the Anglo-Saxons call "Theory of Mind", which expresses the ability to imagine oneself in the place of others.

Mindfulness thus makes it possible to generate positive emotions such as serenity, peace, joy, while reducing, or even erasing, the "self-concern" that is part of mental wandering.

Attention is another important function of the brain. It is linked to the activity of another neural network, the “Positive Task Network” (TPN). In the waking state, the brain is solicited by a large quantity of information and receives many external and internal stimuli. It is the attention which, at a given moment, chooses one of the information received according to one of these three “salient” criteria: threat, pleasure and novelty. The functions of attention include directing attention, maintaining attention, and shifting attention.

What is the relationship between mind wandering and attention?

There is an antagonism between these two mental states. When one appears, the other disappears and vice versa. When a person performs a specific task and their mind wanders, their attention drops and they become less efficient in the current task. Just a second of inattention, loss of concentration, and it's the loss of a match, a failed show or a more or less serious accident... Conversely, directing and maintaining attention on a specific task eliminates mental wandering. On the neurological level, this antagonism has been demonstrated by the inverse activity relationships of these two neuronal networks, the DMN and the TPN, measured by functional MRI.

What is the mechanism of action of meditation on these two mental states?

The key to meditation, we now know, lies in one word: attention. “Awareness” or “mindfulness” is part of the Eightfold Path taught by the Buddha. The definition of Mindfulness by Jon Kabat-Zinn, the father of MBSR (Mindfulness-Based Stress Reduction), is a “state of consciousness that results from paying attention, intentionally, to the present moment, without judging the experience that is unfolding moment after moment”. Thanks to neuroscience, we now understand the mechanism of action of Mindfulness. Attention, for example, to breathing, to noises or to what is happening in the mind, activates the Positive Task Network (TPN), and deactivates the Default Mode Network (DMN), thus mental wandering . Mindfulness therefore acts by playing on the antagonism between attention and mental wandering. This has been demonstrated by medical imaging in meditators, regardless of the type of meditation used in the experiment conducted. Mindfulness thus makes it possible to generate positive emotions such as serenity, peace, joy, while reducing, or even erasing, the “self-concern” which is part of mental wandering.