A team of American scientists has reported that regions of the brain involved in emotional regulation are larger in long-term meditators than in non-meditators. The group used high-resolution magnetic resonance imaging (MRI) to scan the brains of 22 participants, all of whom had extensively practiced meditation. They compared the scans with those of age-matched controls. Those who meditated had been doing so for between five and 46 years and practised a variety of styles, including zazen, samatha and vipassana. These styles have many practices in common, such as breath control, visualisation and attention to external and internal stimuli. Meditation time ranged from 10 to 90 minutes a session, with most meditators having daily sessions. MRI showed that regular practice of meditation is associated with increased thickness in a subset of cortical regions related to sensory, auditory, visual and internal perception. Meditators showed significantly larger volumes of the right hippocampus, right orbito-frontal cortex, right thalamus and left inferior temporal gyrus — all regions important in emotional regulation and response control. Most of the regions identified in the study were found in the right hemisphere, associated with sustaining attention, which is a central practice of meditation. The authors conclude that larger volumes in these regions might account for meditators' ability to cultivate positive emotions, retain emotional stability and engage in mindful behavior. (The underlying anatomical correlates of long-term meditation: Larger hippocampal and frontal volumes of gray matter. Neuroimage. 2009 Jan 13. [Epub ahead of print]).