-
Nature Neuroscience Sep 2022Fiber photometry enables recording of population neuronal calcium dynamics in awake mice. While the popularity of fiber photometry has grown in recent years, it remains...
Fiber photometry enables recording of population neuronal calcium dynamics in awake mice. While the popularity of fiber photometry has grown in recent years, it remains unclear whether photometry reflects changes in action potential firing (that is, 'spiking') or other changes in neuronal calcium. In microscope-based calcium imaging, optical and analytical approaches can help differentiate somatic from neuropil calcium. However, these approaches cannot be readily applied to fiber photometry. As such, it remains unclear whether the fiber photometry signal reflects changes in somatic calcium, changes in nonsomatic calcium or a combination of the two. Here, using simultaneous in vivo extracellular electrophysiology and fiber photometry, along with in vivo endoscopic one-photon and two-photon calcium imaging, we determined that the striatal fiber photometry does not reflect spiking-related changes in calcium and instead primarily reflects nonsomatic changes in calcium.
Topics: Action Potentials; Animals; Calcium; Corpus Striatum; Mice; Neurons; Photometry
PubMed: 36042311
DOI: 10.1038/s41593-022-01152-z -
Pharmacology, Biochemistry, and Behavior Feb 2021The combined development of new technologies for neuronal recordings and the development of novel sensors for recording both cellular activity and neurotransmitter...
The combined development of new technologies for neuronal recordings and the development of novel sensors for recording both cellular activity and neurotransmitter binding has ushered in a new era for the field of neuroscience. Among these new technologies is fiber photometry, a technique wherein an implanted fiber optic is used to record signals from genetically encoded fluorescent sensors in bulk tissue. Fiber photometry has been widely adapted due to its cost-effectiveness, ability to examine the activity of neurons with specific anatomical or genetic identities, and the ability to use these highly modular systems to record from one or more sensors or brain sites in both superficial and deep-brain structures. Despite these many benefits, one major hurdle for laboratories adopting this technique is the steep learning curve associated with the analysis of fiber photometry data. This has been further complicated by a lack of standardization in analysis pipelines. In the present communication, we present pMAT, a 'photometry modular analysis tool' that allows users to accomplish common analysis routines through the use of a graphical user interface. This tool can be deployed in MATLAB and edited by more advanced users, but is also available as an independently deployable, open-source application.
Topics: Data Analysis; Fiber Optic Technology; Neurons; Optical Fibers; Photometry; Synaptic Transmission; User-Computer Interface
PubMed: 33385438
DOI: 10.1016/j.pbb.2020.173093 -
Nature Methods Oct 2021The quantification of membrane-associated biomolecular interactions is crucial to our understanding of various cellular processes. State-of-the-art single-molecule...
The quantification of membrane-associated biomolecular interactions is crucial to our understanding of various cellular processes. State-of-the-art single-molecule approaches rely largely on the addition of fluorescent labels, which complicates the quantification of the involved stoichiometries and dynamics because of low temporal resolution and the inherent limitations associated with labeling efficiency, photoblinking and photobleaching. Here, we demonstrate dynamic mass photometry, a method for label-free imaging, tracking and mass measurement of individual membrane-associated proteins diffusing on supported lipid bilayers. Application of this method to the membrane remodeling GTPase, dynamin-1, reveals heterogeneous mixtures of dimer-based oligomers, oligomer-dependent mobilities, membrane affinities and (dis)association of individual complexes. These capabilities, together with assay-based advances for studying integral membrane proteins, will enable the elucidation of biomolecular mechanisms in and on lipid bilayers.
Topics: Dynamins; Lipid Bilayers; Photometry; Proteins
PubMed: 34608319
DOI: 10.1038/s41592-021-01261-w -
Current Opinion in Chemical Biology Jun 2022We review recent advances in our ability to characterise biomolecular structure, interactions and associated dynamics by mass photometry (MP), the label-free detection... (Review)
Review
We review recent advances in our ability to characterise biomolecular structure, interactions and associated dynamics by mass photometry (MP), the label-free detection and mass measurement of individual biomolecules in solution. Molecular counting and identification provides direct access to relative abundance, and thereby affinities, while associated dynamics yield on- and off-rates. The molecular resolution afforded by MP enables these measurements as a function of stoichiometry and assembly at equilibrium, as opposed to the majority of existing solution-based methods. Together with future improvements in terms of assays and technological performance, MP is likely to provide mechanistic details of complex biomolecular processes.
Topics: Molecular Dynamics Simulation; Photometry
PubMed: 35405425
DOI: 10.1016/j.cbpa.2022.102132 -
Cell Reports Methods Mar 2023Here, we present simultaneous fiber photometry recordings and optogenetic stimulation based on a multimode fused fiber coupler for both light delivery and collection...
Here, we present simultaneous fiber photometry recordings and optogenetic stimulation based on a multimode fused fiber coupler for both light delivery and collection without the need for dichroic beam splitters. In combination with a multi-color light source and appropriate optical filters, our approach offers remarkable flexibility in experimental design and facilitates the exploration of new molecular tools at minimal cost. We demonstrate straightforward re-configuration of the setup to operate with green, red, and near-infrared calcium indicators with or without simultaneous optogenetic stimulation and further explore the multi-color photometry capabilities of the system. The ease of assembly, operation, characterization, and customization of this platform holds the potential to foster the development of experimental strategies for multi-color fused fiber photometry combined with optogenetics far beyond its current state.
Topics: Brain; Optogenetics; Photometry
PubMed: 37056369
DOI: 10.1016/j.crmeth.2023.100418 -
European Biophysics Journal : EBJ May 2021Mass photometry (MP) is a relatively new experimental technique with a quickly expanding list of applications. Using optical detection, MP measures the mass of...
Mass photometry (MP) is a relatively new experimental technique with a quickly expanding list of applications. Using optical detection, MP measures the mass of individual molecules to obtain molecular mass distributions of proteins and other biomolecules in solution. The combination of speed, sensitivity, and very low sample consumption with label- and immobilization-free detection sets MP apart from other analytical methods. An increasing number of laboratories incorporates mass photometry as a routine sample analysis technique. However, MP measurements can sometimes be challenging, especially for users without previous experience with single-molecule techniques. Here, we present a protocol for the determination of protein molecular mass distributions by MP. It describes the sample and materials preparation as well as data collection and analysis. The advantages and limitations of this technique and the potential sources of artifacts are also given. This protocol can be used by new MP users and serve as a checklist for laboratories routinely performing MP experiments to guide consistent data collection and documentation.
Topics: Nanotechnology; Photometry; Proteins
PubMed: 33651123
DOI: 10.1007/s00249-021-01513-9 -
Cell Reports Methods Jul 2022Fiber photometry is an emerging technique for recording fluorescent sensor activity in the brain. However, significant hemoglobin absorption artifacts in fiber...
Fiber photometry is an emerging technique for recording fluorescent sensor activity in the brain. However, significant hemoglobin absorption artifacts in fiber photometry data may be misinterpreted as sensor activity changes. Because hemoglobin exists widely in the brain, and its concentration varies temporally, such artifacts could impede the accuracy of photometry recordings. Here we present use of spectral photometry and computational methods to quantify photon absorption effects by using activity-independent fluorescence signals, which can be used to derive oxy- and deoxy-hemoglobin concentration changes. Although these changes are often temporally delayed compared with the fast-responding fluorescence spikes, we found that erroneous interpretation may occur when examining pharmacology-induced sustained changes and that sometimes hemoglobin absorption could flip the GCaMP signal polarity. We provide hemoglobin-based correction methods to restore fluorescence signals and compare our results with other commonly used approaches. We also demonstrated the utility of spectral fiber photometry for delineating regional differences in hemodynamic response functions.
Topics: Neurons; Brain; Photometry; Artifacts
PubMed: 35880016
DOI: 10.1016/j.crmeth.2022.100243 -
Sheng Li Xue Bao : [Acta Physiologica... Apr 2021In recent years, fiber photometry has been widely used in the field of neuroscience as an important technique for recording the activity of neurons in the specific... (Review)
Review
In recent years, fiber photometry has been widely used in the field of neuroscience as an important technique for recording the activity of neurons in the specific nuclei of freely moving animal. This review summarized the application of single-channel, multi-channel, and multi-color fiber photometry techniques in the neuroscience research of cognition, behavior, psychology and neurological diseases. In addition, it briefly introduced the applications of fiber photometry combined with functional magnetic resonance imaging technology, and fiber photometry combined with probe technology in the neuroscience research.
Topics: Animals; Magnetic Resonance Imaging; Neurons; Photometry
PubMed: 33903892
DOI: No ID Found -
Nano Letters Jun 2012There is an increasing interest in using graphene (1, 2) for optoelectronic applications. (3-19) However, because graphene is an inherently weak optical absorber (only...
There is an increasing interest in using graphene (1, 2) for optoelectronic applications. (3-19) However, because graphene is an inherently weak optical absorber (only ≈2.3% absorption), novel concepts need to be developed to increase the absorption and take full advantage of its unique optical properties. We demonstrate that by monolithically integrating graphene with a Fabry-Pérot microcavity, the optical absorption is 26-fold enhanced, reaching values >60%. We present a graphene-based microcavity photodetector with responsivity of 21 mA/W. Our approach can be applied to a variety of other graphene devices, such as electro-absorption modulators, variable optical attenuators, or light emitters, and provides a new route to graphene photonics with the potential for applications in communications, security, sensing and spectroscopy.
Topics: Equipment Design; Equipment Failure Analysis; Graphite; Light; Nanoparticles; Photometry; Surface Plasmon Resonance
PubMed: 22563791
DOI: 10.1021/nl204512x -
ChemistryOpen May 2023Understanding biological mechanisms operating in cells is one of the major goals of biology. Since heterogeneity is the fundamental property of cellular systems, single... (Review)
Review
Understanding biological mechanisms operating in cells is one of the major goals of biology. Since heterogeneity is the fundamental property of cellular systems, single cell measurements can provide more accurate information about the composition, dynamics, and regulatory circuits of cells than population-averaged assays. Electrochemiluminescence (ECL), the light emission triggered by electrochemical reactions, is an emerging approach for single cell analysis. Numerous analytes, ranging from small biomolecules such as glucose and cholesterol, proteins and nucleic acids to subcellular structures, have been determined in single cells by ECL, which yields new insights into cellular functions. This review aims to provide an overview of research progress on ECL principles and systems for single cell analysis in recent years. The ECL reaction mechanisms are briefly introduced, and then the advances and representative works in ECL single cell analysis are summarized. Finally, outlooks and challenges in this field are addressed.
Topics: Single-Cell Analysis; Electrochemical Techniques; Luminescent Measurements; Photometry
PubMed: 35880657
DOI: 10.1002/open.202200113