Fiber Photometry-An Ultimate User Guide and Overview

What is fiber photometry? How to set up a fiber photometry operation? How to choose the most efficient fiber photometry accessories? Our complete guide on the fiber photometry system can give you all the answers.

This guide consists of 4 chapters that are arranged according to different phases of the fiber photometry journey.

Chapter 1 introduces the basic knowledge of the fiber photometry system.

Chapter 2 explains the working principle, advantages, and shows the steps of setting up the relevant experiment.

Chapter 3 elaborates the functions of different fiber photometry models and provides successful case studies to show the range of applications.

Chapter 4 gives recommendations on choosing the most efficient fiber photometry accessories to improve the experiment in practice.

In case you know little about fiber photometry…

Fiber photometry system is an optical imaging method that enables researchers to detect the activity of large neuronal populations in freely-moving animals for a long period of time, which helps to explore the correlation between neuronal activity and animal behaviors.

Chapter 1: Fiber Photometry Learning Guide for Beginners

Brief Introduction:

Fiber photometry is an optical method that is based on the principle of measuring the light emitted from fluorescent molecules via time-correlated single-photon counting (TCSPC)- based fiber optics. From this principle, we know that the realization of this experiment requires probe tools that can express fluorescence in the tissue, as well as a set of equipment that can transmit fluorescence and detect it.

Then we look at the fluorescence tools first. Currently the most commonly used fluorescence tools are divided into calcium indicators, neurotransmitter indicators, voltage indicators and so on. Because there are many kinds of animal models for experimental applications, and also we need to study specific brain regions or even specific kinds of cells, gene editing techniques have been widely used for probe development.

Common genetically encoded calcium indicators (GECIs) are fluorescent proteins derived from green fluorescent protein (GFP, etc.) and its variants (e.g., circularly arranged GFP, YFP, CFP, RFP, etc.) fused to calmodulin (CaM) and the M13 domain of myosin light chain kinase. When Ca2+ is present, it binds to CaM, leading to interaction between the M13 and CaM structural domains, triggering a structural rearrangement of cpEGFP, which enhances the green/red fluorescence signal.

The more widely used GECIs are: GCaMP, Pericams, Cameleons, TN-XXL and Twitch, among which GCaMP6, GCaMP7 are now widely used in in vivo calcium imaging studies due to its superior sensitivity. The following is a summary of the types of the common GECIs.

Chapter 2: More About Fiber Photometry: Working Principle and Process

For instance, advantages of Fiber photometry.

The study of the nervous system of awake and freely moving animals is a crucial issue in contemporary neuroscience research. By detecting calcium signals associated with neuronal activity, we are able to better understand complex neural circuits. In recent years, technological developments including two-photon microscopy, single-photon microscopy, and fiber photometry have allowed us to perform real-time detection of changes in calcium signals in animals. The application of these techniques requires engineered fluorescent proteins.