The RWD R820 Tricolor Multichannel Fiber Photometry System is a powerful new fiber photometry system with an integrated lightweight body and richer software features. It can record red & green fluorescence signals, such as GCaMP, RCaMP, dLight, and jrGECO1a, while a unique 410nm LED is used to acquire control signals and exclude noise.
Fiber photometry calcium imaging is becoming increasingly popular in neuroscience research and, based on its advantages, is now an indispensable tool for the real-time detection of neural signals.
R810 Dual Color Multichannel Fiber Photometry System has two excitation light sources (410nm and 470nm). The 410 nm can be used to reflect the background noise signal, thus ensuring the acquisition of true fluorescence data.
The R820 Tri-Color Multichannel Fiber Photometry System has three excitation light sources (410nm, 470nm and 560nm). The system can record signal of green fluorescence indicator like GCaMP and dLight or neurotransmitter probe and red fluorescence indicator like RCaMP, jrGECO1a or neurotransmitter probe.
Main Applications:
- Ca2 + and neurotransmitter signal detection
- Study the function of neural circuits
- Explore the mechanisms of neurological diseases
- Develop new fluorescent sensor probe
- Experiment of optical principle
Principle:
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.
Fiber photometry calcium imaging has been in development for nearly a decade and has been highly rated by many laboratories. It can be used to explore the regulatory mechanisms behind animal behavior.
In fiber photometry, data are collected by analyzing the fluorescence change (ΔF) relative to the initial baseline fluorescence (F) and observing the signal change corresponding to the calcium transient (ΔF/F). These metrics are usually based on fluorophores such as GFP, RFP, tdTomato, mCherry, etc., of which GCaMP is the most common example.
In neurons, calcium ions regulate several important processes, including neurotransmitter release and membrane excitability. Fiber photometry calcium imaging can provide critical insight into calcium dynamics, as GCaMP fluoresces only when bound to calcium ions. Based on similar principles, fiber photometry systems can also detect changes in the concentration of neurotransmitters.
(Neurotransmitter probes – cpEGFP is embedded in a specific neurotransmitter receptor, and the binding of the receptor to the neurotransmitter triggers a conformational change in the receptor to convert to a fluorescent signal, and this genetically encodable probe is expressed in cells or mouse brain by viral injection, transfection, and other technical means.)
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Advantages:
Integrates data acquisition, analysis & plotting: Bonsai software and MATLAB programming are not required. Data analysis includes data clipping, bleaching correction, smoothing, movement correction, event heat map, peak statistics, and area under curve and heat map of behavior trajectory.
Multiple Behavioral Events Synchronize & Mark: The software can synchronize and mark multiple special behavioral events or external input signals during the experiment.
More Accurate Signal, Avoid Interference: Dual highly sensitive detectors enabling independent and sequential detection to avoid interference of fluorescence excitation and detection, acquiring more accurate signal. The 410nm light source can be used to reflect the background noise signal, thus ensuring the acquisition of true fluorescence data.
Easy Connection to Other Equipment: 4-input and 4-output interface for easy connection with other equipment such as optogenetics and electrophysiology for the closed-loop study of stimulation and recording.
9 Channels Support: Support up to 9 channels, suitable for simultaneous experiment of multiple animals or multiple brain locations
Advantages of Multi-Fiber Photometry System
The fiber photometry system uses a low-cost implanted cannula that does not require a miniscope overhead. Simple animal surgery, lightweight implants, and smaller data files all contribute to the long-term experiments on freely-behaving animals. With high signal-to-noise ratio, and the ability to combine with a variety of behavioral paradigms, the fiber photometry system is used with GCamP, which is one of the genetically-encoded calcium indicators (GECIs), to record neuronal activities.
Despite the fact that electrophysiology generates the highest level of temporal accuracy, its performance falls short in detecting cell-type specific population neuronal activities of the deep brain structures in behaving animals. As an alternative, fiber photometry provides the most sensitive and easiest way to achieve this function while employing one or more multimode optical fibers implanted in the brain.
In regard to the study of behavioral neuroscience, the correlation of neuronal responses with animal behavior is the core paradigm of functional dissection of neural circuits in systems. In most cases, the multi-channel fiber photometry system provides valuable insight into the functional studies of neural circuits. The fiber photometry identifies activities in more than one brain area that need to be simultaneously recorded as neurons in different brain areas respond in coordination during specific task execution. That is why fiber photometry is utilized for investigating how behaviors are produced from the integration of signals in joined brain regions. On top of that, it is efficient and even necessary for studying the neural correlates of social interaction, especially sociosexual behaviors by recording the interaction between different animals.
RWD multi-channel fiber photometry system mainly has four advantages including:
1) High sensitivity-Dual detector +TDM design.
2) Convenient and Efficient: Supports simultaneous recording of 9 channels.
3) Data Visualization: Data acquisition and analysis functions.
4) Feature-Rich Extensions: Multiple interfaces and various event marking.
How the Fiber Photometry System Works
To understand how the fiber photometry system works, the calcium indicators are a good place to start. From a microscopic perspective, several important processes, including neurotransmitter release and membrane excitability, are regulated by calcium ions in neurons.
GECIs change their ability to fluoresce based on whether or not they are bound to calcium. Since the internal concentration of calcium in neurons is very tightly regulated and voltage-gated calcium channels open when a neuron fires an action potential, transient increases in internal calcium concentration, which result in a transient rise in the ability of a GECI to fluorescence, can be a good proxy for neuronal firing.
A two-wavelength GCaMP fiber photometry system（405nm+470nm） is utilized for GCaMP recording. Given that GCaMP fluoresces only when bound to calcium ions, 405 nm LED source is used to photoexcite isosbestic points of the fluorophore. The GCaMP fiber photometry system can provide critical insight into calcium dynamics by recording the calcium-independent GCaMP fluorescence.