Researchers found people who were happier had larger gray matter volume in the precuneus region of the brain.
Study leader Dr. Wataru Sato, of Kyoto University in Japan, and colleagues publish their findings in the journal Scientific Reports.
The definition of happiness has been debated for centuries. In recent years, psychologists have suggested that happiness is a combination of life satisfaction and the experience of more positive than negative emotions - collectively deemed "subjective well-being."
But according to Dr. Sato and his colleagues, the neurological mechanisms behind a person's happiness were unclear.
"To date, no structural magnetic resonance imaging (MRI) investigation of the construct has been conducted," they note.
"Identification of the neural substrates underlying subjective happiness may provide a complementary objective measure for this subjective construct and insight into its information-processing mechanism."
Meditation may boost happiness by targeting precuneus brain region
To address this research gap, the team used MRI to scan the brains of 51 study participants.
After the scans, subjects were asked to complete three short questionnaires that asked them how satisfied they are with their lives, how happy they are and how intensely they feel positive and negative emotions.
The researchers found that individuals who had higher happiness scores had larger gray matter volume in the precuneus of the brain - a region in the medial parietal lobe that plays a role in self-reflection and certain aspects of consciousness - than their unhappy counterparts.
What is more, the researchers found that one's happiness may be driven by a combination of greater life satisfaction and intensity of positive emotion - supporting the theory of subjective well-being.
"These results indicate that the widely accepted psychological model postulating emotional and cognitive components of subjective happiness may be applicable at the level of neural structure," they add.
These findings, the researchers say, indicate that individuals may be able to boost their happiness through practices that target the precuneus, such as meditation:
"Previous structural neuroimaging studies have shown that training in psychological activities, such as meditation, changed the structure of the precuneus gray matter.
Together with these findings, our results suggest that psychological training that effectively increases gray matter volume in the precuneus may enhance subjective happiness."
Dr. Sato adds that, while further research is required, these current findings may be useful for developing psychological programs that boost a person's happiness.
Medical News Today recently reported on a study suggesting that more money and more sex does not necessarily make a person happier.