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Two-photon (TP) calcium imaging is an important imaging modality in neuroscience, allowing for large-scale recording of neural activity in awake, behaving animals at behavior-relevant timescales. Interpretation of TP data requires the accurate extraction of temporal neural activity traces, which can be accomplished via manual or automated methods. In this work we seek to improve the accuracy of both...
The reconstruction of the neural network is essential in computational neuroscience. Here, we present an automatic algorithm to trace single neuron projections based on two core algorithmic ideas: a global step segmenting all neuron bodies and their projections and a local growing phase that accommodates to the nonuniform illumination and to the noise of the sample. We tested our algorithm on two...
Two-photon time-resolved photoluminescence has been recently applied to various semiconductor devices to determine carrier lifetime and surface recombination velocities. So far the theoretical modeling activity has been mainly limited to the commonly used one-photon counterpart of the technique. Here we provide the analytical solution to a 3D diffusion equation that describes two-photon microscopy...
The development of technologies that allow for live optical imaging of exocytosis from β-cells has greatly improved our understanding of insulin secretion. Two-photon imaging, in particular, has enabled researchers to visualize the exocytosis of large dense-core vesicles (LDCVs) containing insulin from β-cells in intact islets of Langerhans. These studies have revealed that high glucose levels induce...
Model-based decision making requires prediction of future states by action-dependent state transition models. To investigate their neural implementation, mice were trained to do an auditory virtual navigation task and neuronal activity was recorded in the posterior parietal cortex (PPC) and the posteromedial cortex (PM), with the genetically encoded calcium indicator GCaMP6f after gene transfer by...
Over the past decade, novel live-imaging techniques have considerably changed our vision of cell biology, in particular in the field of neuroscience. Acquisitions of 3D image sequences over long periods of time, in particular, have enabled neurobiologists to follow complex processes such as the development of neuronal populations or degenerative events occurring in pathological contexts, improving...
Animal models were developed for chronic observation with using two-photon microscopy. To demonstrate potency of the models, T-cell and macrophage migration in inguinal lymph node, spleen, abdominal cavity and kidney were observed for two weeks on single mice. The image quality was maintained high enough during an observation period to count and trace cell population and migration.
Vocal fold scarring is one of the major cause of voice disorders yet there is no reliable treatment. We hypothesized to solve this problem by creating sub-epithelial voids to localize biomaterials to restore the pliability of scarred vocal folds. In order to guide this precise surgery, there is a need for performing deep tissue imaging. Here, we present an ex-vivo study to investigate maximum imaging...
We developed an animal model for chronic observation with using two-photon microscopy. To demonstrate potency of the model, T-cell migration and proliferation in inguinal lymph node were observed for two weeks on single mice. The image quality was maintained enough high during a observation period to count and trace cell population and migration.
The use of two-photon microscopy allows for imaging of deep neural tissue in vivo. This paper examines frequency-based analysis to two-photon calcium fluorescence images with the goal of deriving smooth tuning curves. We present a multifrequency analysis approach for improved extraction of calcium responses in episodic stimulation experiments, that is, when the stimulus is applied for a number of...
Affinity maturation, the fundamental basis for adaptive immunity, is accomplished through somatic hypermutation of B-cell receptors followed by the expansion of rare mutants with higher affinity for the immunizing antigen. This process occurs over a period of weeks in unique microanatomic sites known as germinal centers. Two-photon microscopy has recently made it possible to track individual B cells...
The effect of dispersion of the excitation pulse in two-photon microscopy is examined with a photon-counting microscope in both stationary and scanning modalities, and it is demonstrated that transform-limited pulses provide the best signal yield despite increased bleaching rates.
We propose a novel method for axonal bouton modeling and automated detection in populations of labeled neurons, as well as bouton distribution analysis for the study of neural circuit organization and plasticity. Since axonal boutons are the presynaptic specializations of neural synapses, their locations can be used to determine the organization of neural circuitry, and in time-lapse studies, neural...
Two-photon microscopy has grown up to be an important technique in biology research, particularly in exploring the neuronal functions of the neurons. With large penetration depth and three-dimensional selectivity, this technique has been able to address the neuro-computing in brain slice or even in live animals. However, its imaging rate is limited by the mechanic scanning mechanism and cannot satisfy...
The paper reports on the investigation of the nonlinear optical properties of nanosized grains of Fe(IO3)3, recently synthesized with a simple and inexpensive process. The measurements have been carried out using a Ti:sapphire femtosecond oscillator coupled to an inverse microscope modified to detect the polarization dependence of the signal. It is shown that Fe(IO3)3 crystals (20-70 nm) can be efficiently...
We report on a one-shot approach for measuring two-photon action cross section without tuning the excitation wavelength. The results obtained by this method show good agreement with that obtained by conventional methods using tunable lasers.
By implementing two-photon optical-beam-induced-current microscopy using a solid-immersion lens, imaging inside a silicon flip chip is reported with 166 nm lateral resolution and an axial resolution capable of resolving features only 100 nm deep.
Using two-photon microscopy, we quantify changes in blood flow after photothrombotic occlusion of individual blood vessels in rat neocortex, and find that flow reverses direction at the first branch that lies downstream from localized clots.
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