The structural differences in the insular cortex might relate to enhancements of body awareness in Vipassana (insight meditation) practitioners observed in behavioral, physiological, magnetoencephalographic, and functional neuroimaging research. Insula involvement in enhanced body awareness  may also be an explanation for the consistent findings of the changes in this region in meditation practitioners. Since problems with the perception of the body and the emotions engendered by introceptive symptoms are involved in depression and anxiety, a greater ability to accurately represent the body  may play a role in the emotional and clinical benefits that  apparently results from meditation.

Insular Cortex in meditation

Although the anterior precuneus is a relatively poorly understood region, it is suggested to have a role in higher-order body image, self-related processing, and attentional shifting. These roles are consistent with the emphasis on the present moment-centered, body-oriented awareness cultivated in many meditation traditions ( particularly Vipassana). The anterior precuneus shows strong functional connectivity with primary and secondary somatomotor cortices, insula, and superior parietal cortex. Therefore, structural differences in this region may be involved in the higher-order integration of heightened interoceptive and exteroceptive attention, potentially mediated by insula and somatomotor cortices, or other forms of self-processing and evaluation. Therefore, this integration may aid in achieving the greater present-centered awareness, and transformed view of the self that is advocated in many meditation traditions.

Anterior precuneus in meditation

Mindfulness meditation training can reduce the perceived unpleasantness of painful stimuli, which is related to an altered function or structure in somatosensory cortices. The ability of meditation practitioners to focus on the sensory qualities of painful and unpleasant stimuli, rather than the emotional and self-related cognition that might result from unpleasant stimuli, may be an underlying cause of morphometric changes in somatosensory cortices. Alteration of the somatomotor cortical structure by mental training alone is also consistent with research that shows that imagining or dreaming of somatomotor activities results in higher blood-oxygen-level-dependent (BOLD) signal in these regions, although there was not any muscle activity or explicit sensory input. Therefore, these studies suggest that attention is sufficient to significantly modulate activity in these brain areas. As a result, attention may also be enough to significantly modulate brain structure in these regions.

Somatomotor Cortices

Somatomotor cortices

Anterior precuneus

Insular cortex

University of Georgia

Eight regions of the brain are consistently altered in long and short-term  meditators. These regions include:

The frontopolar cortex ( also known as the Brodmann's area 10 or the rostrolateral prefrontal cortex)

The sensory cortices and insula

The hippocampus

The anterior cingulate cortex

The mid-cingulate cortex

The orbitofrontal cortex

The superior longitudinal fasciculus

The corpus callosum

Brain regions consistently altered in meditation practitioners

Wang, P. P., & Jernigan, T. L. (1994). Morphometric studies using neuroimaging. Neurologic clinics, 12(4), 789–802.

Morphometric studies using neuroimaging. 

The rostrolateral prefrontal cortex becomes more active at the start of the meditative practice. It also is more active during focused attention, open awareness, and Zen meditations.  The meditation practices of the individuals that had structural differences in the rostrolateral prefrontal cortex were Insight, Tibetan Buddist, and Brain Wave Vibration (BMV) meditation.

The rostrolateral prefrontal cortex in meditation

 The processes that the anterior cingulate cortex and mid-cingulate cortex, such as self-control, emotion regulation, and behavioral flexibility; are emphasized in meditation. Behavioral evidence shows improvements in pain regulation , emotional awareness, emotion regulation , and insightful problem solviging in meditation practitioners.  Meditation practice may lead to more conscious action selection, greater attention to thoughts and information in the decision-making process, and increased attention to the movement of the body during action execution, which are all processes that the anterior cingulate cortex and mid-cingulate cortex are focused on. Frequent recruitment of the anterior cingulate cortex and mid-cingulate cortex for conscious action control might relate to the consistently observed differences in the structure of these regions.

The anterior cingulate cortex and the 
mid-cingulate cortex in meditation

The orbitofrontal cortex in meditation

Sensory Cortices and Insula in meditation

Meditation training may enhance stress resilience via hippocampal structure alterations. This notion comes from the idea that hippocampal atrophy is associated with clinical disorders that involve stress, anxiety, and depression. These clinical disorders may also be associated with problems of concentration and memory. Thus, structural increase in the hippocampus relate to meditation's potential betterment of these clinical conditions.  There may also be structural differences in the hippocampus because of memory reconsolidation.  Many meditative practices place a strong emphasis on re-evaluating past behavioral patterns and default emotional reactions to events. 
The differences in the hippocampus may be due to the region playing a role in seeing past experiences in a new light and allowing for greater flexibility in present behavior.  Structural differences in the hippocampus may be related to the effort involved in re-contextualizing spontaneous thought processes, memories, and simulations during meditation practice.

Hippocampus in meditation

Morphometric differences observed in the corpus callosum are mostly localized to the anterior regions, which are thought to preferentially connect to the prefrontal brain regions.  These prefrontal brain regions include the frontopolar cortex, anterior insula, orbitofrontal cortex, and anterior and mid-cingulate cortices. Therefore, prefrontal structural increases may follow structural changes of particular corpus callosum areas that reciprocally connect bilateral prefrontal gray matter regions. 

Corpus Callosum in meditation

The posterior projection areas of the superior longitudinal fasciculus  are implicated in higher-order spatial processing, which includes the representation of the body in three-dimensional space and the directing of attentional focus in space Structual changes in the superior longitudinal fasciculus are consistent with findings in the anterior precuneus, insular and somatomotor cortices, the rostrolateral prefrontal coprtex and the anterior cingulate cortex. 

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