During a nine-month meditation program called ReSource, researchers had 300 participants practice three different kinds of meditation. Each had a particular focus like improving attention, compassion or cognitive skills. The subjects were examined through a number of approaches like MRI, with the scientists finding significant brain alterations during each three-month block.  

Veronika Engert, a neuroscience researcher who authored one of the two papers published on the subject by the Max Planck, reflected on the changes: 

"We were surprised [by] how much can actually happen in three months, because three months isn't that long," said Engert.

Mindfulness-based meditation was one part of the study. The subjects were asked to practice it 30 minutes each day six days a week. The meditation involved focusing on the breath, while keeping eyes closed. After the three months, the participants exhibited thickening in the prefrontal cortex of the brain, according to Engert’s interview with Live Science. That is the area responsible for complex thinking, attention and personality. 

Another focus of study was a three-month session based on "socio-effective competency," involving meditation geared towards compassion, gratitude and dealing with difficult emotions. This also produced unique brain alterations. 

"If people train [in the skill of] perspective-taking, we see changes in brain regions that are important for these cognitive processes," explained Engert.

In the third part of the study, the participants had to respond to a stressful situation like a job interview or school exam. All the people who practiced meditation were less stressed out than those who were not. Interestingly, those who were using the compassion-based meditation that encouraged them to understand the perspective of another person showed lower levels of cortisol, a stress hormone. 

"After this type of a stress test we usually see that cortisol rises after about 20 minutes," said Engert. "This rise in cortisol was lower by 51 percent in those subjects who had the social training."

Professor Tania Singer, the principal investigator of the ReSource Project, highlighted the importance of their findings to understanding brain plasticity. 

"Even though brain plasticity in general has long been studied in neuroscience, until now little was known about the plasticity of the social brain," said Singer. "Our results provide impressive evidence for brain plasticity in adults through brief and concentrated daily mental practice, leading to an increase in social intelligence."

She pointed out that empathy and compassion are crucial for the welfare of our society, leading to cooperation and conflict resolution. Perhaps, meditation practices can play a role in spreading these important skills.

You can read the papers published by the Institute on the subject here in Science Advances.