Whether it’s cats, trains or Christmas presents that float your boat, it’s pretty well established that different things make different people happy. Yet in spite of our individual tastes, it turns out there’s one that brings all of us joy: gray matter.

This is according to a team of scientists from Kyoto University, which devised an experiment to uncover the neural basis of happiness. Publishing their findings in the journal Scientific Reports, the researchers found that people with higher levels of subjective happiness tended to have a greater volume of a type of tissue called gray matter in the right precuneus – a region of the brain that is considered to play a central role in generating subjective consciousness, such as thoughts and feelings.

It is important to note that the researchers were not seeking to identify the parts of the brain that produce temporary happy feelings or moods, but those that are responsible for a person’s overall happiness as a stable neurological trait. This is based on previous studies which indicate that a person’s happiness can be reliably measured over long periods, suggesting that it may be caused by more than just fleeting moments of pleasure, but by permanent neural substrates.

In an attempt to identify these, the team recruited 51 volunteers who were then subjected to a series of psychiatric questionnaires that have previously been used to measure cognitive and emotional character traits. Among these were the Subjective Happiness Scale and the Purpose In Life Test, each of which had been adapted to relate specifically to Japanese participants.

Once an overall measure of subjective happiness had been obtained for each subject, the scientists took magnetic resonance imaging (MRI) scans of their brains in order to try and identify a correlation between these scores and neurological variations.

In particular, they focused on brain regions such as the anterior cingulate gyrus, the medial parietal cortex (where the precuneus is located) and the amygdala, since a number of previous studies have shown these areas to be highly involved in the generation of happy emotions. Results showed “a significant positive relationship between the subjective happiness score and gray matter volume in the right precuneus.”

As a consequence, the team concluded that by integrating both the emotional and cognitive components of happiness, the precuneus may help mediate subjective happiness. Furthermore, the team insists that the structure of a person’s precuneus gray matter is far from fixed, and can be manipulated through psychiatric training exercises. For instance, separate studies have shown that regular meditation produces alterations in the volume of gray matter in this region of the brain, thereby suggesting that such activities could help to increase happiness levels.

However, while the team believes that its findings are significant, it also concedes that happiness is a complex phenomenon that may be caused by a combination of neural pathways. The researchers therefore suggest that the volume of gray matter in the precuneus could well just represent one part of the puzzle, and recommend further research in order to establish the relationships between the neural subcomponents of happiness.