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Solutions de photométrie à fibre

La photométrie par fibre est une technique de neuroimagerie puissante permettant de surveiller l'activité des populations neuronales chez les animaux en activité, notamment les rongeurs et les primates.

To observer neuronal activity, prior to the cannula implantation, the des campagnes marketing ciblées, brain area is injecté avec genetically-encoded fluorophore indicateurs including GCaMP, dLight, GRAB-Ach, RCaMP, jRGECO1, etc. entre autres. Those indicators posséder fluorescence properties, meaning they emit light at a longer wavelength after absorbing light at a shorter wavelength (excitation light). However, for this fluorescence to occur, the indicators must also bind to molécules (Par exemple, dopamine, acetylcholine, ions calcium), which increase during neuronal activity. Therefore, by measuring the fluorescent emission from brain tissue, researchers can indirectement measure the level of molécules as an indicative of neuronal population activité during complex behaviors.  

La fibre photometry method offers several advantages, including low invasiveness, low cost, simplicity compared to other methods, and the possibility to moniteur deep brain areas. Nonetheless, there are drawbacks to consider, par exemple : le spatial resolution of the photometry signal est limité à neuronal populationen contrary to our Miniature Microscopy Systems that resolve single cell imagerie.  

Fiber Photometry Systems Comparison

Doric Lenses Inc. est un leader reconnu dans le développement de produits de pointe pour la photométrie par fibre chez les animaux en comportement, stimulant l'innovation dans ce domaine en évolution rapide. The image below gives an overall summary of all photometry les systèmes so far designed in the company. Each system is meticulously designed to meet specific needs and challenges encountered by users.  

Three main categories of photometry systems divided based on their detector:  

  1. Système de base: photodetector with high sensitivity and high temporal resolution. 
  1. Bundle Systems: CMOS camera images multiple fibers simultaneously. 
  1. FluoPulses System: fast photodetector measures changes in fluorescence durée de vie. 

 

Basic Fiber Photométrie Système  

Systèmes de base de photométrie à fibre are designed to record fluorescence signals sampled with one optical fiber per cube. However, it is possible to combine multiple cubes to record from more than one souris or brain site. Doric Lenses offers three (3) different system configurations to accommodate experiments with freely moving animals.  The Fiber Photometry Mini-Cube (FMCs), Rotary Fiber Photometry Mini-Cube (RFMC)ainsi que, Wireless Photometry système.

The FMCs  vous be dessouscategorized into 3 types (FMC, iFMCet ilFMC) en fonction de lair niveau d'intégration (Voir l'image ci-dessous). The FMC has an all-optical fluorescence cube with external light sources and detector pour l'enregistrement photométrie signaux. This conception modulaire le fait très personnalisables for different applications. The iFMC bien que, only requires a separate light source as the photodétecteur is integrated within the cube purposefully to augmentere the signal-to-noise ratio. La ilFMC contient all detector et light sources within the cube. Therefore, not only the signal-to-noise ratio améliorers, but also the system is simpler and user-friendly.  Notamment unll FMC les systèmes can be used with our pigtailed rotary joints (FRJ_1x1_PT, FRJ_2x2_PT & AFRJ_2x2_PT) Pour either 1-site or 2-site long terme, se déplacer librement expériences. 

In Rotatif Fiber Photometry Mini-Cube (RFMC) le fluorescence cube, the excitation light and the detectors are embedded on the rotary joints itself. This unique setup minimizes movement artifacts in the signal, resulting in more reliable data collection. Pendant ce temps, the detector is also embedded inside the cube to increase the signal-to-noise ratio. Therefore, RFMC system boasts the highest quality signal recording among all options, albeit at a slightly higher cost. La rotation joint aussi contient a hollow channel for passing extra cables or tubes for optogenetic stimulation, fluid delivery, or electrophysiology recording, at a distinct site from the photometry sites.  

Lastly, considering that wired setups often lead to tanglproblèmes in freely moving animal, notamment pendant et les sciences sociales interagirion CMS of several mice in the same cage, at Doric Lenses, nous avons récemment développé a new solution, le Wirrésistible Photometry product. Two excitation light, one detector and all electronics and optics are integrated onto léger fonctionnant sur batterie headstage with wireless communication. This system is ideal to study neural population underpinning social behaviors but est limité à 1-color green emission detection (500-550 nm) with 2 excitations; isosbestic (405, 415 nm) and functional (470 nm). 

All basic systems utilisé lock-in or interleaved signal demodulation CMS algorithmes. La photodétecteurs of basic systems aussi capture data at a high sampling rate, which is then down sampled to 60 Hz. En outre, le FMC systems are compatible with red-shifted optogénétique plus de le photométrie site, tout en RFMC can only Support optogenetic stimulations in a different site.  

Système de photométrie à fibre groupée  

While the basic fiber photometry systems are typiquement designed to record from a single mice brain, still plusieurs cubes can be combined to record from several mice or several brain regions. However, this approach rapidly increases the complexity of the setup and poses challenges in synchronizing the recordings, especially for 3+ sites/animals 

À propos this issue, Doric Lenses has designed series of Bundle Photometry System, specified for simultané recording from multiple animals or divers brain regions of a single mice (1-19 target regions), all at a reasonable price. 

The Bundle Photometry System includes 3 subcategories including the Système de photométrie à fibre groupée (BFMC), Bundle Fiber Photometry with Targeted Optogenetic (BFTO) Et le Rotary Bundle Fiber Photometry (RBFMC) (see image below). 

La BFMC has two version depending on the integration level. The newer version of BFMC system has a fully integrated design (CMOS camera, LEDs, LED Driver & console), greatly simplifying the set up compared to the standard BFMC combustion propre. However, both BFMC systems are not compatible with optogenetics.   

La BFTO system is specifically designed to combine multi-fiber photometry and targeted optogenetics. Independent multi-site optogenetic control is ideal for close-loop optogenetics (both multi-animal and/or multi-site) experiments. This system provides the greatest flexibility for common neuroscience experiments. 

Unlike the BFMC and BFTO systems, the RBFMC has a rotating cube that helps eliminate movement artifacts, allowing for high-quality signals. However, this benefit comes at the cost of being limited to recording different brain regions from a single mouse. Additionally, the RBFMC includes optogenetic capabilities that can illuminate all sites simultaneously.  

All bundle systems use CMOS camera detector that images entire fiber bundle simultaneously. The power LEDs excite the entire fiber bundle, and the photometry signal is then sampled at 10-20 Hz depending on the configuration.  

FluoPulse™ 

FluoPulse™ is a novel photometry system from Doric Lenses which works by measuring fluorophores lifetime rather than fluorescence intensity level. It is designed to mesurer la fluorescence lifetimes ranging between 1-10 ns et peut résoudre differences in lifetime of 10-20 ps. The measured photometry lifetimes are then averaged at 10 Hz to obtain photometry signal.  

Thus, it is compatible with most biosensors designed for Fluorescence Lifetime Microscopy (FLIM) and Förster’s Resonance Energy Transfer (FRET), including FLIM-AKAR, GRAB-Ach3.0, etc.  

Par sampling fluorophores lifetime rather than intensity, FluoPulse™ offers several advantages, including highly stable fluorescence imaging which is robuste to sensor expression level, autofluorescence, photobleaching, excitation power, and movement artifacts and ambient light. This makes it ideal for long-term studies lasting weeks or months, as well as for comparing results across different animals, time points, and brain regions.  

Références externes (Système de photométrie à fibre optique de base)

1. Protocol for in vivo dual-color fiber photometry in the mouse thalamus. Star Protocol.10.1016 (2024). Lien 
2. Sharma S et al. La voie inhibitrice de la zone incerta médiane entraîne un comportement exploratoire en inhibant les neurones cunéiformes glutamatergiques. Nat. Commun. 15(1):1160 (2024). Lien 
3. Lee YH et al. Les neurones récepteurs de la leptine hypothalamique latérale stimulent la recherche de nourriture et les comportements de consommation liés à la faim chez les souris mâles. Nat. Commun. 14(1):1486 (2023). Lien
4. Khalil V et al. La voie sous-cortico-amygdale traite les menaces innées et apprises. elife. 12:e85459 (2023). Lien
5. Conde-Berriozabal S et al. Circuits du cortex M2 et altérations comportementales induites par les sens dans la maladie de Huntington : rôle du colliculus supérieur. J. Neurosci. 43(18):3379-3390 (2023). Lien
6. Linders LE et al. La potentialisation induite par le stress des synapses hypothalamiques latérales sur les neurones dopaminergiques de l'aire tegmentale ventrale entraîne une augmentation de la consommation d'aliments savoureux. Nat. Commun. 13(1):6898 (2022). Lien
7. Chen D et al. Déconstruction d'un axe sympathique astrocyte hypothalamique-adipocyte blanc qui régule la lipolyse chez la souris. Nat. Commun. 13(1):7536 (2022). Lien
8. Zessen RV et al. L'activité dopaminergique évoquée par les signaux et les récompenses est nécessaire au maintien des associations pavloviennes apprises. J. Neurosci. 41(23):5004-5014 (2021). Lien 
9. Tecuapetla F et al. L'activité équilibrée dans les voies de projection des noyaux gris centraux est essentielle pour les mouvements contraversifs. Nat. Commun. 5, 4315 (2014). Lien
10. Lerner TN et al. Les analyses du cerveau intact révèlent des informations distinctes véhiculées par les sous-circuits dopaminergiques SNc. Cellule 30, 635-47 (2015). Lien 
11. Kim CK, et al. Mesure rapide et simultanée de la dynamique des circuits à plusieurs endroits du cerveau des mammifères. Nat Methods 13, 325-8 (2016). Lien

 

Références externes (Système de photométrie à faisceau de fibres)

 1. Sayar-Atasoy N et al. Les neurones AgRP codent le temps d'alimentation circadien. Nat. Commun. 27(1):102-115 (2024). Lien
2. Zhuo Y et al. Capteurs GRAB verts et rouges améliorés pour la surveillance de l'activité dopaminergique in vivo. 21(4):680-691 (2024). Lien
3. Qian T et al. Un capteur génétiquement codé mesure la libération temporelle d'ocytocine à partir de différents compartiments neuronaux. Nat Biotechnol. 41(7):944-957 (2023). Lien
4. Guillaumin MCC et al. Démêler le rôle des cellules NAc D1 et D2 dans l'alimentation hédonique. Mol Psychiatry. 28(8):3531-3547 (2023). Lien
5. Toader AC et al. Le thalamus antéromédial régule la sélection et la stabilisation des souvenirs à long terme. Cellule. 186(7):1369-1381.e17 (2023). Lien
6. Sayar-Atasoy N et al. Modulation adrénergique de la voie de la mélanocortine par les signaux de la faim. Nat. Commun. 14(1):6602 (2023). Lien
7. Aklan I et al. Les neurones sérotoninergiques du raphé dorsal suppriment l'alimentation via des circuits redondants du prosencéphale. 69:101676 (2023). Lien