Buyer’s guide
How to choose a fiber photometry system
Check the colors, channels, light power, sampling rate, sync and software against your experiment, then price every part you need to record.
Match the light colors to your sensors
Each sensor fluoresces brightest under one color of light. Green sensors such as GCaMP and dLight need blue light near 470 nm, and red sensors such as jRGECO1a need light near 560 nm.
A third light, near 405 to 410 nm, is the isosbestic control. Under it, a green sensor such as GCaMP glows the same whatever the cells are doing. Changes in this control signal come mostly from movement or bleaching, and you can subtract them.
Ask the seller
- Which colors does it have, and at what wavelengths?
- Does it have a control light near 405 to 410 nm for green sensors?
- Can it record a green and a red sensor through the same fiber?
- Can I choose which colors run in each session?
Count the fibers you will record at once
Sellers count channels in different ways, so start from fibers. Each fiber is one brain site in one animal, and two sites in each of four mice make eight fibers.
Count the fibers in your largest session, then leave room for the next study.
Ask the seller
- How many fibers can it record at the same time?
- Does its channel count mean fibers, or fibers times colors?
- Can the fibers go to different animals in one session?
- What patch cord does each fiber need, and what does it cost?
- Can I add fibers later?
Check how finely you can set the light power
Too little light gives a weak, noisy signal, and too much bleaches the sensor faster. Look for fine steps at low power, and measure the power at the fiber tip before each session, because cords and implants lose some light.
Ask the seller
- What power range does it reach, and is that measured at the fiber tip?
- In what steps can I set the power?
- Can I set the power for each color and each fiber?
- How do I check the power at the fiber tip?
Find the sampling rate for each color
Many camera-based systems light one color per frame, in turn. The rate for each color is then the total frame rate divided by the number of colors. A system running 60 frames a second across three colors gives each color 20 samples a second.
Check the rate for each color against how fast your sensor responds.
Ask the seller
- What is the top sampling rate, and is it per color or shared?
- Can I record for hours without dropped frames?
- Can I change the rate for each experiment?
Plan how it will sync with behavior and other equipment
To read a trace, you line it up with events such as a lever press or a tone. Digital inputs, often called TTL inputs, mark those events in the recording. Digital outputs let the system start a camera, a pump or a stimulation laser.
Ask the seller
- How many TTL inputs and outputs does it have?
- Can it record video of the animal in step with the signal?
- Can it trigger an optogenetics laser, and record at the same site?
- Can my behavior box start a recording, or a recording start the box?
Look at the analysis software before you buy
Most raw traces go through the same steps. First correct for bleaching and movement. Then express the change from baseline as ΔF/F or a z-score, and line the trace up with your events.
Software that runs these steps saves writing your own code, and files you can export let you check each step later.
Ask the seller
- Does it show ΔF/F live while I record?
- Does it use the control signal to correct for movement and bleaching?
- Can it plot the signal around each event, as peri-event plots and heat maps?
- Can I export the raw traces and event times as CSV?
- Can a new student run it without writing code?
List every part you need to record
A system may arrive ready to record or need several more parts. Before you compare prices, list the patch cords, fiber optic cannulas, mating sleeves, a rotary joint if the animal moves freely, a behavior camera and a computer.
Ask the seller
- Which patch cords and sleeves come with it?
- Are the patch cords made for low autofluorescence?
- Do the core size and numerical aperture of the cords match my cannulas?
- Which ferrule size does it use, 1.25 mm or 2.5 mm?
- Is a computer included, with the software installed?
- Does it come with a camera to record behavior?
Add up the full price of the setup
Add the parts you listed in check 7 to the price of the system. A low base price can leave out the cords, implants and support you need.
Ask the seller
- What does the full setup cost, with every cord and implant?
- What does the warranty cover, and for how long?
- Is installation or training included?
- What does support cost after the first year?
- Can I get a written quote for my purchasing office?
Common questions
- What is fiber photometry?
- Fiber photometry records the activity of a group of cells through an optical fiber implanted in the brain. Light sent down the fiber makes a sensor in the cells glow, and the same fiber carries the glow back to a detector.
- What is the isosbestic control?
- It is a light near 405 to 410 nm, at which a green sensor such as GCaMP gives the same glow at rest and when active. Changes in this control signal come mostly from movement, bleaching or the fiber, and you remove them from the sensor signal.
- How many channels do I need?
- You need one for each fiber you record at once, so one site in each of six animals needs six. Ask whether a seller counts channels as fibers or as fibers times colors.
- Can I record a green and a red sensor at the same time?
- Yes, with a system that has a light for each, near 470 nm for green and 560 nm for red. Ask whether both record through the same fiber, and whether one color bleeds into the other.
- Can I combine fiber photometry with optogenetics?
- Yes. Choose a stimulation color away from the colors your sensor uses. The laser then barely excites the sensor, and the photometry light is less likely to drive the opsin. Some systems can record and stimulate through the same fiber.
- Do I need a rotary joint?
- You need one when a freely moving animal turns during long sessions, so the patch cord does not twist. Short sessions in a small arena may not need one.
How our Tricolor system fits these checks
The Tricolor Multichannel Fiber Photometry System records green and red sensors, with a 410 nm control light. Its specifications answer most of the checks. For the rest, such as the rate per color and the power per fiber, ask us.
Colors and control
It has three lights, at 410 nm for the isosbestic control, 470 nm for green sensors such as GCaMP and dLight, and 560 nm for red sensors such as RCaMP and jRGECO1a.
Channels
It records from up to 9 fibers at once, at several brain sites or in several animals.
Light power
You set the power in 0.1 µW steps, up to a maximum of at least 100 µW.
Sampling rate
It records up to 250 frames a second.
Sync with behavior
It has 4 digital inputs and 4 digital outputs. A separate optogenetics output sends pulses at 0 to 500 Hz, and the system can record and stimulate at the same site. Its behavior camera records at 1920 by 1080 pixels and 30 frames a second, or 1280 by 720 and 60.
Software
Its software shows ΔF/F live and needs no programming. It corrects for bleaching and movement, and makes event heat maps, peak statistics and the area under the curve.
What is included
It comes with the main unit, a computer with the software installed, a behavior camera on a stand and a device to photobleach the patch cord. It includes one low-autofluorescence patch cord, 2 m long with a 200 µm core and 0.37 NA, and a ceramic sleeve. You choose the cord and sleeve for 1.25 mm or 2.5 mm ferrules.
Price
The system costs $29,900 with the parts above. Fiber optic cannulas, more patch cords and a rotary joint are sold separately.
Cannulas and patch cords
See the Tricolor system
Read its full specifications, or tell us about your setup.
