Telefipho Wireless Fiber Photometry

Telefipho Wireless Fiber Photometry

We would like to tell you about TeleFipho, Amuza’s new wireless fiber photometry system. It’s our newest way to track calcium and neurotransmitters, and it works in real-time in freely moving animals. It’s easy to use, easy to process your data, and it’s ready to go right out of the box.

Fiber photometry is one of the newest tools available to neuroscientists who wish to correlate behavior with neural activity. It’s a powerful, ultra-fast technique used to measure calcium, neurotransmitters and other molecules in vivo in real-time. But until now the technique has required a connection – a fiber optic cable connecting the research animal to the rest of the optical hardware outside of the cage. This cable limits animals’ freedom of movement and social interactions. It is also fragile and can make your data noisier. This, in turn, can limit the design of your experiments.

Fiber Photometry Schematic

Telefipho Schematic

With Telefipho all of the optical hardware – light source, optical filters, and photodetector – are combined in a small headstage. The rechargeable headstage communicates by radio with a base station. Your animals can move through tunnels and doorways and interact freely during experiments. Telefipho can also improve video tracking: tracking software often confuses a swaying cable with a mouse that is still moving. This can complicate the scoring of freezing behavior during fear conditioning.

The headstage mounts directly on an FC size fiber optic cannula without any intervening cables or interconnects. This maximizes light transmission and minimizes noise and artifacts. This headstage weighs just 3 grams and has been tested with both mice and rats.

To use the system, an optical fiber is implanted with the tip placed at the brain region of interest. Blue light from an LED in the headstage is sent through the fiber to excite the fluorescent sensors expressed in the target region. The sensor molecules fluoresce in proportion to the concentration of the analytes, and some of the fluorescent light travels back through the fiber to be measured by a photodetector. A fluorescence filter cube, combining bandpass filters for excitation, a bandpass filter for emission, and dichroic mirrors are used to remove extraneous wavelengths and separate the light paths. The headstage transmits the data to the base station and then to your computer.

Since only a single narrow fiber is implanted inside the skull, the technique is much less invasive than imaging, especially for targets deep inside the brain.
The fluorescent signal is recorded and allows tracking of changes in analyte levels on a subsecond time scale.

TeleFipho data is also easy to work with. Removing the cable means removing the motion artifacts caused by rotary joints and long flexible waveguides, so you won’t have to process your data to correct for them.

TeleFipho software provides a real-time view of the data, allowing you to quickly optimize light levels and detection sensitivity. You can manually add timestamps and notes to the data, or you can connect your behavioral equipments’ outputs to TeleFipho and automatically align behavioral events with the fluorescence data.

You can also send the signal to your own recording equipment and process the data using your own software.

With the ever-increasing number of genetically encoded fluorescent indicators for molecules beyond calcium, such as dopamine, glutamate, acetylcholine, norepinephrine, endocannabinoids, and even cyclic monophosphates, fiber photometry is certain to become a versatile tool in your lab. This is doubly true since the vectors used to express the sensors are becoming increasingly precise at targeting specific cell types and circuits so that results are increasingly specific with less interference from off-target cells and molecules.

If you would like to learn more about TeleFipho fiber photometry, please contact Amuza.

Questions?

Wireless Fiber Photometry: Measuring Neurochemicals In Vivo in Real Time

Wireless Fiber Photometry: Measuring Neurochemicals In Vivo in Real Time

Amuza and Teleopto launch the first commercial wireless fiber photometry system at Neuroscience 2019

Our wireless optogenetic users have frequently asked us if we could provide wireless photometry – we are happy to announce that now we can!

TeleFipho wireless headstages allow your freely behaving animals to move with true freedom, enabling novel experimental approaches with fiber photometry. The 3 gram headstages are optimized for GCaMP and other GFP based indicators.

TeleFipho includes all of the components required for fiber photometry – light source, filter cube, photodetector, and wireless transmission hardware – in a 3 gram headstage.

What is Fiber Photometry?

Fiber Photometry is a powerful technique for measuring rapid changes in neuromodulators in vivo via fluorescence. It is most commonly used  to measure fast (subsecond) changes in concentrations of calcium in freely behaving animals, but it is now also capable of being used to monitor neurotransmitters and other molecules.To use fiber photometry, genetically encoded fluorescent indicators are first expressed at the location of interest. When excited by light of the right wavelength, these proteins fluoresce – but only while they are bound to their target analyte. As local concentrations of the analyte rise and fall, the fluorescence intensity rises and falls in response. Genetically encoded calcium indicators (GECIs), such as GcAMP have been the mainstay of fiber photometry and also for calcium imaging, a closely related technique. Recently dopamine indicators (Dlight1, GRABDA) and norepinephrine indicators (GRABNE) have been introduced, and more neurochemical sensors are in development. 

To capture this signal  in vivo, an optical fiber is implanted at the target region in the animal. The other end of the fiber is attached to the photometry hardware. First an LED or laser light source passes light through the fiber to excite the indicator proteins in the target region. The resulting fluorescent light then travels back through the fiber to a photodetector, creating a record of the changing concentrations of the analyte. Careful filtering and splitting of the light traveling through the fiber optic is required to separate the light used for excitation from the fluorescence being sent to the photodetector. 

Why use Fiber Photometry?

The most frequent use is to measure changes in calcium levels at synapses as a proxy for changes in neural activity, helping researchers discern the links between behavior states and the firing patterns of neurons. But the same technique is also used to monitor the activity of GPCRs and ion channel drug targets. 

When used with freely moving animals, fiber optic tethers can be problematic. The cable can prevent animals from using exercise wheels or shelters or get tangled in complicated environments, limiting behavioral testing. Cables can also cause artifacts when used with video tracking software. For example, the cable often continues to sway after the animal has stopped moving, making it difficult to recognize freezing behavior during fear conditioning studies. Placing all of the necessary components for fiber photometry in a small lightweight headstage ends these problems.

TeleFipho has been tested with both mice and rats. The data above shows stress induced (tail pinch) changes in GCaMP signals from hypothalamic orexin neurons in mice. GCaMP is a genetically encoded calcium indicator often used to monitor calcium dynamics. Data is Courtesy of Dr. Daisuke Ono in the Akihiro Yamanaka Lab, Nagoya University.

Shrinking the components for fiber photometry has an added bonus: it also allows us to shrink the price. Telefipho starts at roughly half of the cost of other commercial fiber photometry systems.

Please stop by our booth during SfN 2019 to ask for a demonstration and visit our product page for more information.

Questions?