Training emotional muscles of the brain - special issue of Emotion

The February issue of the journal Emotion is devoted to studying psychological, physiological, emotional correlates of mindfulness meditation. One interesting study from Grant et al. suggest we can train the 'emotional muscle' of our brain.  They turned up the heat on a metal cube applied to the legs of 17 male and female Zen meditation practitioners between the ages of 22 and 57, and 18 matched controls. On average, the meditators, who had between 2 and 30 years of daily practice, tolerated an extra 2°C before saying they were in moderate pain. The team then took MRI scans of the subjects and measured the thickness of several pain-processing cortical regions. The meditators had greater thickness in the region of the anterior cingulate cortex thought to mediate pain's unpleasantness. Here is their abstract:

Zen meditation has been associated with low sensitivity on both the affective and the sensory dimensions of pain. Given reports of gray matter differences in meditators as well as between chronic pain patients and controls, the present study investigated whether differences in brain morphometry are associated with the low pain sensitivity observed in Zen practitioners. Structural MRI scans were performed and the temperature required to produce moderate pain was assessed in 17 meditators and 18 controls. Meditators had significantly lower pain sensitivity than controls. Assessed across all subjects, lower pain sensitivity was associated with thicker cortex in affective, pain-related brain regions including the anterior cingulate cortex, bilateral parahippocampal gyrus and anterior insula. Comparing groups, meditators were found to have thicker cortex in the dorsal anterior cingulate and bilaterally in secondary somatosensory cortex. More years of meditation experience was associated with thicker gray matter in the anterior cingulate, and hours of experience predicted more gray matter bilaterally in the lower leg area of the primary somatosensory cortex as well as the hand area in the right hemisphere. Results generally suggest that pain sensitivity is related to cortical thickness in pain-related brain regions and that the lower sensitivity observed in meditators may be the product of alterations to brain morphometry from long-term practice.