This is Your Brain on Meditation

They tell you not to have any goal in mind when you choose to meditate. But that is not quite right. We humans have reasons for everything we do, and meditation is no different. In the case of modern westerners, most of us meditate to make our brains younger and more supple, and to reduce the effects of stress and worry on our brains and bodies.

Below, I link to two brief summaries of scientific studies on how meditation affects the brain. The first excerpt is from 2015, and the second is from 2020. Finally, I reproduce a table from this 2020 review article which summarizes several MRI studies that looked at the differences in brain cortical thicknesses and specific brain center volumes between meditators of various schools and those who did not meditate.

Excerpt 1 from 2015:

Increased Grey Matter/Cortical Thickness in the following key areas:

• Anterior Cingulate Cortex: Increased grey matter changes were noted in the anterior cingulate cortex (ACC), which is a structure located behind the brain’s frontal lobe. It has been associated with such functions as self-regulatory processes, including the ability to monitor attention conflicts, and allow for more cognitive flexibility.

• Prefrontal Cortex: Increased grey matter density was also found in areas of the prefrontal lobe, which are primarily responsible for executive functioning such as planning, problem solving, and emotion regulation.

• Hippocampus: Increased cortical thickness in the hippocampus has also been noted. The hippocampus is the part of the limbic system that governs learning and memory, and is extraordinarily susceptible to stress and stress-related disorders like depression or PTSD.

Decreased Amygdala Size:

Studies have shown that the amygdala, known as our brain’s “fight or flight” center and the seat of our fearful and anxious emotions, decreases in brain cell volume after mindfulness practice.

The summary of scientific findings in the above excerpt suggests that meditators develop better skills of discrimination, decision-making, and emotional control — or better executive functions generally.

Source

The second excerpt is from a 2020 article:

Research has shown that there are several ways that meditation can change the brain’s structure and function:

  • Enlarges the prefrontal cortex. This area of the brain is responsible for rational decision-making. Studies have shown that meditation increases grey matter (brain cells) in this region.1
  • Shrinks the amygdala. The amygdala is a key brain structure known as the emotional or fear center of the brain. Smaller amygdalae found in more mindful people are associated with greater emotional control.2
  • Thickens the hippocampus. This hippocampus is key for learning and memory. Just a few weeks of mindfulness meditation practice increased the size of this brain region.3
  • Increases overall grey matter. Grey matter, brain cell bodies important for processing power and linked to intelligence, seem to increase with meditation training.4
  • Enhances high-amplitude gamma brainwave activity. High-frequency gamma waves correlate with states of heightened awareness and bliss. Long-term meditators have been shown to have more gamma wave activity both before and during meditation.5

It’s important to note that it can take many years to produce these more permanent changes in brain structure. Yet some of the studies mentioned above showed changes starting to occur after just a few weeks of meditation practice.

The summary of scientific findings in the second excerpt above substantiates the claims of the first excerpt, and adds that overall brain grey matter is increased along with enhanced gamma wave activity — which generally correlate with higher levels of conscious activity.

The table below is excerpted from a 2020 article in Frontiers in Bioscience:

Image Source

Table 1. Main MRI studies

MeditationMRI analysisMain results(meditation x control)Reference
insight meditation (vipassana)cortical thicknessGreater cortical thickness in the right anterior insula and in the right middle and superior frontal sulci.Lazar et al., 2005 (21)
Vipassanavoxel-based morphometryGreater gray matter volumes in the left inferior temporal gyrus, the right anterior insula and the right hippocampus.Hölzel et al., 2008 (24)
Dzogchenvoxel-basedmorphometryAltered gray matter densities in the medulla oblongata, left superior frontal gyrus, the left inferior frontal gyrus, the left mid-ventrolateral prefrontal cortex, bilaterally the anterior lobe of the cerebellum and the left fusiform gyrus.Vestergaard-Poulsen et al., 2009 (28)
Zen mediationCortical thicknessThicker cortices in the dorsal anterior cingulate cortex and bilaterally in the secondary somatosensory cortex.Grant et al., 2010 (31)
integrative body mind trainingfractional anisotropyIncreased fractional anisotropy values in the left anterior corona radiata, body and genu of the corpus callosum, superior corona radiata and superior longitudinal fasciculus.Tang et al., 2010 (33)
Shamatha, Vipassana, andZazenDiffusion Tensor ImagingLarger fractional anisotropy in fiber tracts such as the anterior thalamic radiation, cingulum-hippocampus, corticospinal tract, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, superior longitudinal fasciculus, temporal component of superior longitudinal fasciculus, uncinate fasciculus and forceps minor.Luders et al., 2011 (37)
Mindfulness-based stress reductionvoxel-based morphometryIncrease in gray matter concentration in a region of interest within the left hippocampus; increases of gray matter concentration. In whole brain analysis, increase in gray matter concentration in the posterior cingulate cortex, the left temporo-parietal junction and the cerebellum.Hölzel et al., 2011 (40)
several disciplinesDiffusion Tensor ImaginIncreased fractional anisotropy in several regions of the corpus callosum.Luders et al., 2012 (39)
Brain Wave Vibrationcortical thickness/Diffusion Tensor ImagingIncreased cortical thickness in the bilateral ventromedial prefrontal cortex, superior frontal cortex, temporal pole, middle and inferior temporal cortices, left fusiform cortex and medial prefrontal cortex on meditators. Meditators showed higher fractional values in the cuneus, precuneus and occipital regions and the ventromedial prefrontal cortex and lower fractional anisotropy values in the right medial prefrontal cortex, posterior cingulate cortex and right occipital regionsKang et al., 2013 (43)
Sahaja Yoga Meditationvoxel-basedmorphometryLarger gray matter volume overall and with regional enlargement in the right inferior temporal gyrus and bilaterally the anterior insula and left ventrolateral prefrontal cortex, the right ventromedial orbitofrontal cortex.Hernández et al., 2016 (19)
Loving-kindness meditationvoxel-based morphometryGreater gray matter volume in the right angular gyrus, right posterior parahippocampal gyrus, left inferior temporal gyrus and middle temporal gyrusLeung et al., 2013 (52)
several disciplinesvoxel-based morphometryLarger left hippocampal volume.Luders et al., 2013 (57)
several disciplinescortical gyrificationEnlargement in the pre and post central gyrus, central sulcus, left inferior/middle temporal gyrus, angular gyrus, parieto-occipital fissure, fusiform gyrus, parietal operculum and cuneus and the right anterior dorsal insula.Luders et al., 2012 (58)
soham meditationvoxel-based morphometryHigher gray matter volume in the left ventral pallidum, left supplementary motor area and brainstem.Kumar et al., 2014 (60)

Table 2. Main functional MRI studies

MeditationConditionMain resultsReference
Kundaliniduring meditationIncreased activity in putamen, midbrain, pregenual, anterior cingulate cortex, and hippocampal/parahippocampal formationLazar et al., 2000 (66)
ACEM meditationduring meditation taskMeditavion vs Waiting interval: increased activity in the left superior temporal gyrus Meditation vs control task: increased activity in the left inferior frontal gyrus Meditation vs word sequence generation task: increased activity in the left superior temporal gyrusDavanger et al., 2010 (68)
Tibetan Buddhist traditionmeditation vs resting stateIncreased activity in the frontal parietal regions, insula, lateral occipital, thalamic nuclei, basal ganglia and cerebellum in expert meditators and novice meditators during meditation x resting. Novice meditators and most expert meditators (skill acquired) showed less effort during meditation while least expert meditators showed greater activation of attention-related brain regions.Brefczynski-Lewis et al., 2007 (65)
focused attention-to-breathmeditation and passive viewing during cued aversive picturesDecreased amygdala activity and increased prefrontal integration of the amygdala.Doll et al., 2016 (69)
Soham meditationmeditation vs control task – classify geometric Figures between blue and yellow.During meditation: increased activity in the left mPFC, left inferior frontal gyrus, supplementary motor area and left precuneus control task: increased activity in the left middle and superior middle temporal, left inferior parietal and left post-central gyrus.Guleria et al., 2013 (70)
compassion meditation (CM)CM or reappraisal during film clips (negative or neutral stimuli)CM vs negative stimuli: increased activity in the left prefrontal cortex and frontal cortex, supplementary motor area, areas in parietal lobules, and temporal gyrus, anterior cingulate cortex, posterior cingulate cortex, thalamus, hypothalamus, ventral pallidum, globus pallidus, caudate, putamen, portions of the cerebellum and right amygdala. CM vs. reappraisal: meditation had increased activity in the ventromedial prefrontal cortex, medial orbitofrontal cortex, gyrus rectus, portions of anterior cingulate cortex, frontopolar cortex, supplementary motor area, mid-cingulate, precuneus, bilateral superior temporal gyrus and inferior frontal gyrus/operculum, right fusiform gyrus, bilateral amygdala, hypothalamus, caudate, globus pallidus, putamen, right hippocampus and portions of the thalamus. Reappraisal, increased activity in the middle temporal gyrus, posterior cingulate/precuneus and cerebellum, bilateral medial frontal gyrus and left inferior frontal gyrus, pre-supplementary motor area/medial superior frontal gyrus, left calcarine gyrus.Engen and Singer 2015 (71)
Mindful Attention Training (MAT), Cognitively-Based Compassion Training (CBCT)IAPS databaseCBCT vs. MAT and control: negative correlation to negative images and depression scores in amygdala activity. MAT vs. control: decreased activity in the right amygdala for all images of the IAPS. Also decreased activity in right amygdala throughout the 8 weeks of intervention in response to all images and positive valence images of the IAPS.Desbordes et al., 2012 (74)
Frontiers in Bioscience

MRI studies — especially fMRI studies — are always subject to criticism. As expected, the results from the fMRI studies are subject to wildly varied interpretation.

What we are looking for is consistency between studies, along with theoretical/neurological plausibility of proposed cause and effect relationships between observed differences in MRI and claimed behavioral effects.

Most westerners will need very good reasons before they will devote many months or years of their lives to the practice of a discipline that appears so far out of the mainstream of their everyday concerns.

The most common argument given in favor of meditation practice is that the discipline adds years or decades of awareness to a person’s life — even if they do not live any longer in absolute years.

Consider if you had only ten years of life left to you, but you had the choice to either continue to age and decline at your current rate — or you could live those ten years at the level of health and fitness you had when you were 20 years old. Then you would drop dead at the end of that time. What would you choose?

It seems that we are given a very similar choice when it comes to awareness/attention/mindfulness practice. We may not live longer, but if our level of brain functioning and engagement is significantly higher, the time we have will be time more worth living.

Think it over. We are entering into unprecedented times. Most of us will need all the equanimity and resiliency that we can muster, as corruption and incompetence at all levels is ratcheted ever tighter. We have to do better than just reacting.

Another interesting study from PNAS 2007

More

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