Introduction
The holidays are often associated with family, friends, cheer, joy, and festivity.
Ever wondered why this was?
The answer lies in your brain.
A team of researchers at the Universty of Copenhagen in Denmark found which parts of your brain cause these holiday-related emotions.
Their equipment of choice? A functional magnetic resonance imaging (fMRI), for its ability to detect changes in blood flow, ultimately detecting areas of activity in the brain. In other words, the fMRI can show which parts of the brain are causing the “holiday spirit.”
The subjects

The study scanned, twenty different subjects, ten of which celebrated Christmas and ten who did not.
My only criticism of this study is the sample size. Twenty participants is a very small number and does not accurately represent the global population. In addition, the subjects all lived in Denmark. Finding a diverse range of ethnicities to limits scientific error.
All of the participants were healthy adults who did not consume any sugary foods before the scans. This would increase dopamine levels and skew the results. That means no eggnog or gingerbread for them! :(.
Testing Methodology
84-holiday-related images were displayed to the participants while their brain was scanned. Images were shown for 2 seconds each in the following pattern: six-holiday images and then 6 non-holiday images.

Results
Differences in the brain activation maps (produced by fMRI) identified the Holiday specific brain activation.
The Holiday group had higher activation levels in the left primary motor and premotor cortex, right inferior and superior parietal lobule, and bilateral primary somatosensory cortex. These areas are associated with spirituality, the six senses, and recognition of emotions in others.
The left and right parietal lobules play a significant role in how the likelihood of believing in spirituality, the exact concept the holidays are centered around.

Conclusion
The authors of the study, believe their needs to be further research on this topic. They explain how the study only examines Christmas neglecting other important holidays such as Chanukah and Kwanzaa.
“Although merry and intriguing, these findings should be interpreted with caution,” they explain. “Something as magical and complex as the Christmas spirit cannot be fully explained by, or limited to, the mapped brain activity alone.”
Sources
[1] http://bmjcom.c.presscdn.com/company/wp-content/uploads/2014/07/christmas-spirit.pdf
[2] http://www.bmj.com/content/351/bmj.h6266
[3] https://www.huffingtonpost.com/entry/holiday-season-brain_us_5672f4e9e4b0dfd4bcc0e9ec