scholarly journals All-optical electrophysiology reveals brain-state dependent changes in hippocampal subthreshold dynamics and excitability

2018 ◽  
Author(s):  
Yoav Adam ◽  
Jeong J. Kim ◽  
Shan Lou ◽  
Yongxin Zhao ◽  
Daan Brinks ◽  
...  
Keyword(s):  
High Speed ◽  
Near Infrared ◽  
Neuronal Excitability ◽  
Signal To Noise Ratio ◽  
Brain State ◽  
Promising Tool ◽  
State Dependent ◽  
Subthreshold Voltage ◽  
Targeted Gene Expression

AbstractA technology to record membrane potential from multiple neurons, simultaneously, in behaving animals will have a transformative impact on neuroscience research1. Parallel recordings could reveal the subthreshold potentials and intercellular correlations that underlie network behavior2. Paired stimulation and recording can further reveal the input-output properties of individual cells or networks in the context of different brain states3. Genetically encoded voltage indicators are a promising tool for these purposes, but were so far limited to single-cell recordings with marginal signal to noise ratio (SNR) in vivo4-6. We developed improved near infrared voltage indicators, high speed microscopes and targeted gene expression schemes which enabled recordings of supra- and subthreshold voltage dynamics from multiple neurons simultaneously in mouse hippocampus, in vivo. The reporters revealed sub-cellular details of back-propagating action potentials, correlations in sub-threshold voltage between multiple cells, and changes in dynamics associated with transitions from resting to locomotion. In combination with optogenetic stimulation, the reporters revealed brain state-dependent changes in neuronal excitability, reflecting the interplay of excitatory and inhibitory synaptic inputs. These tools open the possibility for detailed explorations of network dynamics in the context of behavior.

scholarly journals High-speed high-resolution laser diode-based photoacoustic microscopy for in vivo microvasculature imaging

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xiufeng Li ◽  
Victor T C Tsang ◽  
Lei Kang ◽  
Yan Zhang ◽  
Terence T W Wong
Keyword(s):  
High Resolution ◽  
High Speed ◽  
High Performance ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Cost Effective ◽  
High Signal ◽  
Photoacoustic Microscopy ◽  
Mouse Ear

AbstractLaser diodes (LDs) have been considered as cost-effective and compact excitation sources to overcome the requirement of costly and bulky pulsed laser sources that are commonly used in photoacoustic microscopy (PAM). However, the spatial resolution and/or imaging speed of previously reported LD-based PAM systems have not been optimized simultaneously. In this paper, we developed a high-speed and high-resolution LD-based PAM system using a continuous wave LD, operating at a pulsed mode, with a repetition rate of 30 kHz, as an excitation source. A hybrid scanning mechanism that synchronizes a one-dimensional galvanometer mirror and a two-dimensional motorized stage is applied to achieve a fast imaging capability without signal averaging due to the high signal-to-noise ratio. By optimizing the optical system, a high lateral resolution of 4.8 μm has been achieved. In vivo microvasculature imaging of a mouse ear has been demonstrated to show the high performance of our LD-based PAM system.

scholarly journals Induction of an Isoelectric Brain State to Investigate the Impact of Endogenous Synaptic Activity on Neuronal Excitability In Vivo

10.3791/53576 ◽  
2016 ◽  
Author(s):  
Tristan Altwegg-Boussac ◽  
Séverine Mahon ◽  
Mario Chavez ◽  
Stéphane Charpier ◽  
Adrien E. Schramm
Keyword(s):  
Neuronal Excitability ◽  
Synaptic Activity ◽  
Brain State ◽  
The Impact

scholarly journals Upconversion Nanoparticles Decorated with Polysialic Acid for Solid Tumors Visualization In Vivo

2021 ◽  
Author(s):  
P. A. Demina ◽  
N. V. Sholina ◽  
R. A. Akasov ◽  
D. A. Khochenkov ◽  
A. V. Nechaev ◽  
...  
Keyword(s):  
Solid Tumors ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Polysialic Acid ◽  
Lymphatic Drainage ◽  
Circulation Time ◽  
High Signal ◽  
Upconversion Nanoparticles ◽  
Nonspecific Protein Adsorption

Abstract Upconversion nanoparticles (UCNPs) are a promising nanoplatform for bioreagent formation for in vivo imaging, which emit UV and blue light under the action of near-infrared radiation, providing deep tissue penetration and maintaining a high signal-to-noise ratio. In the case of solid tumor visualization, the UCNP surface functionalization is required to ensure a long circulation time, biocompatibility, and non-toxicity. The effective UCNP accumulation in the solid tumors is determined by the disturbed architecture of the vascular network and lymphatic drainage. This work demonstrates an approach to the UCNP biofunctionalization with endogenous polysialic acid for in vivo bioreagent formation. Bioreagents possess a low level of nonspecific protein adsorption and macrophage uptake, which allow the prolongation of the circulation time in the bloodstream up to 3 h. This leads to an intense photoluminescent signal in the tumor.

scholarly journals The short wave near-infrared fluorescence properties of two p-azaquinodimethane (p-AQM)-based conjugated polymers

2020 ◽  
Vol 13 (05) ◽  
pp. 2041003 ◽  
Author(s):  
Yaowei Zhu ◽  
Yawei Miao ◽  
Tingting Xue ◽  
Youchang Liu ◽  
Chunying Zheng ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Biological Tissues ◽  
Infrared Region ◽  
Short Wave ◽  
Quinone Structure ◽  
Living Tissues ◽  
Quinoid Structure

The absorption, scattering, and autofluorescence of biological tissues in short-wave infrared region (SWIR, 900–1700[Formula: see text]nm) are relatively low, so SWIR fluorescence usually has deeper penetration into living tissues, and can show a higher signal-to-noise ratio when used for imaging in vivo. However, there are few types of organic SWIR fluorescent materials currently. In this work, [Formula: see text]-azaquinodimethane ([Formula: see text]-AQM) with a quinoid structure is used as the acceptor unit, and carbazole or fluorene with sp3 hybridization are used as the donor units, two conjugated polymers were synthesized. The quinone structure is conducive to the redshift of absorption and fluorescence spectra, and the sp3 hybridization structure is conducive to weakening the aggregation quenching of polymer fluorescence. PF and PCz exhibited absorption peaks of 492[Formula: see text]nm and 508[Formula: see text]nm, respectively. The emission peaks of the two polymers are 920[Formula: see text]nm and 950[Formula: see text]nm, respectively, both in the short-wave near infrared region. The quantum yield (QY) of PF and PCz is 0.4% and 0.3%, respectively.

scholarly journals Near-infrared turn-on fluorescent probe for discriminative detection of Cys and application in in vivo imaging

RSC Advances ◽  
2019 ◽  
Vol 9 (71) ◽  
pp. 41431-41437 ◽  
Author(s):  
Shaolong Qi ◽  
Lubao Zhu ◽  
Xinyu Wang ◽  
Jianshi Du ◽  
Qingbiao Yang ◽  
...  
Keyword(s):  
Fluorescent Probes ◽  
Biological Samples ◽  
In Vivo Imaging ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Biological Detection ◽  
Signal To Noise ◽  
Turn On

Near-infrared (NIR) fluorescent probes are widely employed in biological detection because of their lower damage to biological samples, low background interference, and high signal-to-noise ratio.

NIR Spectroscopic Detection of Breast Cancer

2005 ◽  
Vol 4 (5) ◽  
pp. 497-512 ◽  
Author(s):  
S. Nioka ◽  
B. Chance
Keyword(s):  
Breast Cancer ◽  
Blood Volume ◽  
Near Infrared ◽  
Tumor Tissue ◽  
Signal To Noise Ratio ◽  
Mirror Image ◽  
Physiological Data ◽  
Cancer Therapies ◽  
Image Position

Near infrared spectroscopy (NIRS) utilizes intrinsic optical absorption signals of blood, water, and lipid concentration available in the NIR window (600–1000 nm) as well as a developing array of extrinsic organic compounds to detect and localize cancer. This paper reviews optical cancer detection made possible through high tumor-tissue signal-to-noise ratio (SNR) and providing biochemical and physiological data in addition to those obtained via other methods. NIRS detects cancers in vivo through a combination of blood volume and oxygenation from measurements of oxy- and deoxy-hemoglobin giving signals of tumor angiogenesis and hypermetabolism. The Chance lab tends towards CW breast cancer systems using manually scannable detectors with calibrated low pressure tissue contact. These systems calculate angiogenesis and hypermetabolism by using a pair of wavelengths and referencing the mirror image position of the contralateral breast to achieve high ROC/AUC. Time domain and frequency domain spectroscopy were also used to study similar intrinsic breast tumor characteristics such as high blood volume. Other NIRS metrics are water-fat ratio and the optical scattering coefficient. An extrinsic FDA approved dye, ICG, has been used to measure blood pooling with extravasation, similar to Gadolinium in MRI. A key future development in NIRS will be new Molecular Beacons targeting cancers and fluorescing in the NIR window to enhance in vivo tumor-tissue ratios and to afford biochemical specificity with the potential for effective photodynamic anti-cancer therapies.

scholarly journals In Vivo Optogenetic Stimulation of Neocortical Excitatory Neurons Drives Brain-State-Dependent Inhibition

2011 ◽  
Vol 21 (19) ◽  
pp. 1593-1602 ◽  
Author(s):  
Celine Mateo ◽  
Michael Avermann ◽  
Luc J. Gentet ◽  
Feng Zhang ◽  
Karl Deisseroth ◽  
...  
Keyword(s):  
Brain State ◽  
Optogenetic Stimulation ◽  
State Dependent ◽  
Excitatory Neurons ◽  
Dependent Inhibition ◽  
Stimulation Of

scholarly journals Photon counting, censor corrections, and lifetime imaging for improved detection in two-photon microscopy

2011 ◽  
Vol 105 (6) ◽  
pp. 3106-3113 ◽  
Author(s):  
Jonathan D. Driscoll ◽  
Andy Y. Shih ◽  
Satish Iyengar ◽  
Jeffrey J. Field ◽  
G. Allen White ◽  
...  
Keyword(s):  
High Speed ◽  
Signal To Noise Ratio ◽  
Photon Counting ◽  
In Vivo Model ◽  
Fluorescence Lifetime Imaging ◽  
Photon Counter ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
Lifetime Imaging

We present a high-speed photon counter for use with two-photon microscopy. Counting pulses of photocurrent, as opposed to analog integration, maximizes the signal-to-noise ratio so long as the uncertainty in the count does not exceed the gain-noise of the photodetector. Our system extends this improvement through an estimate of the count that corrects for the censored period after detection of an emission event. The same system can be rapidly reconfigured in software for fluorescence lifetime imaging, which we illustrate by distinguishing between two spectrally similar fluorophores in an in vivo model of microstroke.

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