- A new meta-analysis examined evidence of how meditation alters brain activity and connectivity.
- The authors found that meditation reorganizes the brain's spatial topography.
- Perhaps this explains why advanced meditators claim to experience “non-dual awareness” — that is, a dissolution of the boundaries between the self and the environment, resulting in a state of unity with the world.
According to the teachings of the Buddha, most of us spend so much time feeling angry or sad about events in the past, or worrying about the future, that we rarely pay enough attention to the present moment.
The aim of meditation is to change this. The term refers to a wide range of practices, all of which have the common purpose of focusing attention on some aspect of the present moment in order to increase awareness of one’s mental state and environment and to decrease stress. Advanced meditators also say that they experience “non-dual awareness” — that is, a dissolution of the boundaries between the self and the environment, resulting in a state of unity with the world.
Numerous brain scanning studies have examined the effects of meditation on brain function. A meta-analysis of these studies interprets their findings with regard to the experience of the self, leading its authors to a new unifying model of how meditation alters brain activity and connectivity.
The new model is based on the assumption that there are three distinct “layers” of self-processing in the brain, which link the body, environment, and mental state: (1) the interoceptive level, which processes signals from the internal organs; (2) the exteroceptive level, which processes sensory stimuli from the outside world; and (3) the mental level of personality and memories.
The so-called topographic reorganization model of meditation emphasizes the roles of the default mode network (which is associated with processing of the mental self and is strongly activated during “mind wandering”) and the central executive network (which plays an important role in attentional mechanisms).
Brain scanning studies show that advanced meditators exhibit decreased activity in the default mode network, as well as increased activity in regions of the central executive network, particularly the dorsolateral prefrontal cortex (dlPFC). At the same time, functional connectivity between the central executive network and default mode network increases.
Reorganizing the brain’s spatial topography
According to the new model, these changes amount to a reorganization of the brain’s spatial topography. A reduction in default mode network activity is indicative of reduced mental self-processing, whereas increased dlPFC activity is associated with the ability to focus attention.
Thus, advanced meditators seem able to shift their attention away from the self and to “synchronize” the three self-processing layers. Normally, mental self-processing takes precedence over exteroceptive and interoceptive signals; that is, awareness is split between the inner and outer worlds.
Meditators can invert the relationship between the layers of self-processing. By focusing more attention on exteroceptive and interoceptive signals, and less on the mental self, they achieve non-dual awareness, and become fully present in the moment. In this state, rather than being separate, the inner and outer world exist in an undivided continuum, and the self, body, and environment are strongly aligned.