Fiber photometry is a technology to detecting the activity of neurons in the brain nucleus of freely moving animals. It sums up the overall fluorescence of neurons expressing a genetically encoded calcium indicator(GECI) or neurotransmitter probes.

The fiber photometry system records changes in the fluorescence intensity of neurons in a specific brain area to reflect neuronal population activity. In the study of neural circuits, the fiber photometry system can perform long-term stable monitoring of the neurons of freely moving animals, and explore the correlation between neural activity and animal behavior.