The study — published Tuesday in Social Neuroscience — found that the reward center of the brain, known as the nucleus accumbens, lights up when Mormon missionaries "feel the spirit."
This is the same area of the brain that is activated by feelings of romantic love, gambling and drugs.
Researchers also found brain regions associated with focused attention as well as moral reasoning, introspection and empathy were activated.
"When we looked at the images, we were really surprised by how consistently we were able to see the same network of brain regions that were active when [participants] reported peak spiritual feelings," said Jeffrey Anderson, a U. neuroscientist who led the study.
Participants had to be 20- to 30-year-old returned Mormon missionaries who were active members of The Church of Jesus Christ of Latter-day Saints. While in the MRI machine, participants were shown clips of spiritually evocative, LDS Church-produced videos and were allowed time to read scriptures and pray.
They then were asked to inform researchers when they were "feeling the spirit," which was then compared to their scans.
Anderson said researchers weren't even sure participants would be able to have a religious experience in an MRI machine.
But most participants were in tears by the end of the hourlong experiment, he said.
The most moving part of the experience for Peterson, who completed her mission in Salt Lake City, was watching a video of Joseph Smith's "First Vision," in which the Mormon founder said God and Jesus appeared to him.
"Because I've seen that and read that several times, not only was I having memories, but I felt emotions, and I felt strongly about it," Peterson said. "It was epic."
Moving forward, Anderson hopes to complete the study with individuals from other religious groups.
"Do we see the same type of patterns in other faith traditions? How universal is this library of brain responses?" Anderson asked. "We'd love to know that."