There are many kinds of meditation and one can go seriously astray by assuming that they are interchangeable. Even within a given meditation tradition there may be differences in the specific instructions for meditating. One of the distinctions that has proven useful in the literature is between focused awareness (FA) and open monitoring (OM) forms of meditation. This roughly corresponds to a distinction between meditation on a single object or invariant set of stimuli (e.g., the breath, a mantra, the name of a revered figure) and open monitoring meditation that is open to any object that shows up (e.g, thoughts, memories, sights and sounds, bodily sensations). Within the Theravada Buddhist tradition, this corresponds to the distinction between concentration meditation (samatha) and insight or mindfulness meditation (vispassana). For the purposes of my review, the focus will be on mindfulness meditation (OM). In addition to the distinctions between FA and OM, the literature differentiates between meditation and sleep and relaxation.
In the literature there is a distinction between state and trait effects. This relates to different but related aims for meditation. The first aim is to induce an altered state during practice. The second aim is to produce long-lasting positive effects on the brain that are present even when the meditator is not actively engaged in meditation. Theoretically it is possible to induce altered states that are similar to or the same as those present while meditating through entrainment technologies, for instance. However, the trait effects likely only develop through practice and represent acquired skills. My primary focus is on developing meditation traits and skills rather than just inducing altered states.
There is great diversity in the technologies used to measure and study the meditating brain. EEG is the oldest. More recently MRI and fMRI have been used extensively. For the purpose of this review, my primary focus will be on EEG studies, the primary reason being that my own experience has been with EEG exclusively. EEG is also a relative inexpensive technology and the least invasive. Furthermore, the emerging neuroshaping technologies that are accessible to the general public use EEG.
The novice/expert model has been employed extensively in this literature nd is relevant to the focus here on meditation skills. Some studies compare inexperienced controls to individuals with modest experience with meditation consisting of days to months, while others compare novices to experts with thousands of hours of experience meditating. There are a host of problems making conclusions about the impact of meditating on the brain from these studies due to all the confounds that arise using individuals at such varying degrees of proficiency in meditation. I will share a study that I did of a Buddhist monk with 30 years of experience with meditation and indicate some of the difficulties that arose in looking at his brain.
Finally, the greatest challenge is looking at the role of neuroshaping technologies in meditation. There is clear support in the literature for meditation itself being a neuroshaping "technology." But the role in developing meditation skills of the newer neuroshaping technologies of neurofeedback and the wearable, "thought controlled computing" devices, has hitherto received little attention.
Please feel free to comment or, if you wish, direct questions and comments to me directly at drampsych at gmail.com.