Meditation and neuroplasticity
The Buddha’s teachings emphasized that the mind can be modified in a positive way via meditation practice, and current research has also described meditation as mental training. Such training might be expected to lead to long-term changes in brain structure and function. Indeed, researchers have suggested that neuroplasticity—structural and functional changes at different levels in the brain—is an outcome of meditative states and meditation practice (e.g., Lutz et al. 2007, 2008a).
One key research question is how much meditation practice it takes to observe changes in brain activities and structures. A number of neuroscience studies suggest that functional and structural changes in the brain linked to meditation can take place on several time-scales. Indeed, one study showed meditation-related changes in brain activity after just four days of meditation practice (with 20 minutes of practice per day) (Zeidan et al. 2011). Another study found that just five days of meditation practice (20 minutes per day) led to enhancements of atten- tional control and immune responses, and a reduction in stress responses (Tang et al. 2007). Other studies (e.g., Farb et al. 2007; Moore and Malinowski 2009; Segal 2002) show pronounced changes in cognitive and emotion regulation processes and related brain activity patterns after eight weeks of meditation training using mindfulness protocols (e.g., MBSR and MBCT). Another study also found that after eight weeks of meditation training there were structural changes in the meditators’ brains, as well as changes in brain activity patterns (Hoelzel et al. 2011). On a longer time-scale, Slagter et al. (2007) found pronounced changes in attentional and conscious access processes and related neural activities among a sample of meditators participating in a retreat lasting three months, with meditation practice for eight hours per day on average (Slagter et al. 2007).
There are also studies showing pronounced differences in brain activity patterns when meditation practitioners with an average of about 16,000 hours of meditation practice are compared with practitioners with an average of about 44,000 hours of meditation practice (Brefczynski-Lewis et al. 2007). Moreover, multiple studies highlight differences in cognitive processes (e.g., attentional networks) between people who undertook eight weeks of mindfulness-based training and people who were long-term insight (vipassana) Buddhist meditators (Jha et al. 2007; van den Hurk et al. 2010).
Studies such as that carried out by Lutz et al. (2004) have shown that brain activity patterns, such as brain rhythms in key areas of the cerebral cortex, appear to change as a function of both meditation expertise (traits) and specific meditation states. These studies confirm that meditation practice leads to stable changes in certain brain activities (e.g., brain rhythms) related to awareness and compassion, outside meditation practice (“off the cushion”) (e.g., Lutz et al. 2004). Such experimental findings suggest that beneficial changes related to meditation, such as calmness, awareness, acceptance, and compassion, are not limited to the periods of meditation practice (e.g., sitting meditation) but are extended into daily life. Reciprocally, in terms of the same neural processes, it is plausible to assume that positive mental states developed in daily life, through the process of developing (informal) awareness, wisdom, and compassion (loving kindness) practice, reverberate positively in formal meditation practice.
Meditation practice appears also to counteract brain ageing processes. For example, a study by Lazar et al. (2005) found a reduced loss of cortical thickness (which depends on the number of neurons and their harborizations in the cortical layers) with ageing in long-term vipassana (insight) meditators in several brain areas involved in cognitive control and emotion regulation, such as the anterior prefrontal cortex and the anterior insula. Such findings suggest that meditation alleviates the effects of cognitive and brain ageing by plausibly enhancing the functioning of cortical circuits and reducing the loss of neurons and synapses with ageing. Following such findings, it also appears important to assess to what extent meditation and mindfulness practices can be protective in respect to dementias in ageing.
Therefore, meditation training appears to influence several important aspects of mind, brain, and behavior, with differential effects depending on meditation expertise. The next section will characterize meditation states and traits in terms of two main categories suitable for psychological and neuroscientific research.