Meditation is a form of mental training that implies intentional, cognitive, and affective strategies to familiarize oneself to inner and outer experiences, to achieve stability and clarity of mind and to exert qualities such as compassion. The neuroscientific research on this topic gathers a wide range of different practices mostly belonging to or inherited from Asian religious, as well as contemplative, and spiritual traditions that have partly been adapted into secular standardized western practices.

Research on meditation regroups at least two distinct questions. The first attempts to understand the neuropsychological processes underlying the practice of meditation. It can be related to the cognitive and affective neuroscience domain, includes a large scale of meditation types usually studied in experienced subjects, and mostly but not exclusively questions the processes occurring when a subject meditates. The second question belongs more to the field of clinical research and relates to the potential effect of meditation on a variety of chronic diseases. These studies usually explore simpler and standardized practices in novices or naive subjects, and typically address long-term effects of the practice on clinical symptoms and associated comorbidities.

Research in cognitive neuroscience in healthy subjects has brought new knowledge about the impact of meditation practice on brain anatomy [1], [2] and function [3], [4], [5] using objective measures. Functional changes in brain connectivity have been reported using functional magnetic resonance imaging (fMRI) [4], [5]. These meta-analyses revealed activations in regions involved in the voluntary regulation of attention (prefrontal and premotor cortex, anterior cingulate gyrus), or in interoception and empathy (insula), while deactivation occurred in regions of the default mode network (DMN) [6] involved in thought wandering [7]. High mindfulness predisposition associated with low anxiety was linked to more flexibility between brain connectivity states in children exposed to stress and adversity [8].

Further to neuroimaging approaches, electroencephalography (EEG) or magnetoencephalography studies have also explored meditation-induced changes on rhythms and on their functional relationships. This paper will review the effects of meditative practice firstly on normal EEG brain activity and secondly in patients with epilepsy.