Versatile Surface Electrodes for Combined Electrophysiology and Two-Photon Imaging of the Mouse Central Nervous System

Understanding and modulating CNS function in physiological as well as pathophysiological contexts remains a significant ambition in research and clinical applications. The investigation of the multifaceted CNS cell types including their interactions and contributions to neural function requires a combination of the state-of-the-art in vivo electrophysiology and imaging techniques. We developed a novel type of liquid crystal polymer (LCP) surface micro-electrode manufactured in three customized designs with up to 16 channels for recording and stimulation of brain activity. All designs include spare central spaces for simultaneous 2P-imaging. Nanoporous platinum-plated contact sites ensure a low impedance and high current transfer. The epidural implantation of the LCP micro-electrodes could be combined with standard cranial window surgery. The epidurally positioned electrodes did not only display long-term biocompatibility, but we also observed an additional stabilization of the underlying CNS tissue. We demonstrate the electrode’s versatility in combination with in vivo 2P-imaging by monitoring anesthesia-awake cycles of transgenic mice with GCaMP3 expression in neurons or astrocytes. Cortical stimulation and simultaneous 2P Ca2+ imaging in neurons or astrocytes highlighted the astrocytes’ integrative character in neuronal activity processing. Furthermore, we confirmed that spontaneous astroglial Ca2+ signals are dampened under anesthesia, while evoked signals in neurons and astrocytes showed stronger dependency on stimulation intensity rather than on various levels of anesthesia. Finally, we show that the electrodes provide recordings of the electrocorticogram (ECoG) with a high signal-to noise ratio and spatial signal differences which help to decipher brain activity states during experimental procedures. Summarizing, the novel LCP surface micro-electrode is a versatile, convenient, and reliable tool to investigate brain function in vivo.

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P2X-GCaMPs as versatile tools for imaging extracellular ATP signaling

10.1101/2020.04.23.057513 ◽

2020 ◽

Author(s):

Matthias Ollivier ◽

Juline Beudez ◽

Nathalie Linck ◽

Thomas Grutter ◽

Vincent Compan ◽

...

Keyword(s):

Signal To Noise Ratio ◽

Atp Release ◽

Cell Types ◽

Extracellular Atp ◽

P2x Receptor ◽

High Signal ◽

Calcium Sensors ◽

Extracellular Signaling

AbstractAdenosine 5’ triphosphate (ATP) is an extracellular signaling molecule involved in numerous physiological and pathological processes. Yet, in situ characterization of the spatiotemporal dynamic of extracellular ATP is still challenging due to the lack of sensor with appropriate specificity, sensitivity and kinetics. Here we report the development of biosensors based on the fusion of cation permeable ATP receptors (P2X) to genetically encoded calcium sensors (GECI). By combining the features of P2X receptors with the high signal to noise ratio of GECIs, we generated ultrasensitive green and red fluorescent sniffers that detect nanomolar ATP concentrations in situ and also enable the tracking of P2X receptor activity. We provide the proof of concept that these sensors can dynamically track ATP release evoked by neuronal depolarization or by extracellular hypotonicity. Targeting these P2X-based biosensors to diverse cell types should advance our knowledge of extracellular ATP dynamics in vivo.

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Three dimensional microelectrodes enable high signal and spatial resolution for neural seizure recordings in brain slices and freely behaving animals

Scientific Reports ◽

10.1038/s41598-021-01528-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

P. Wijdenes ◽

K. Haider ◽

C. Gavrilovici ◽

B. Gunning ◽

M. D. Wolff ◽

...

Keyword(s):

Spatial Resolution ◽

Signal To Noise Ratio ◽

Brain Activity ◽

Three Dimensional ◽

Brain Slices ◽

High Signal ◽

Diagnostic Potential ◽

Freely Behaving

AbstractNeural recordings made to date through various approaches—both in-vitro or in-vivo—lack high spatial resolution and a high signal-to-noise ratio (SNR) required for detailed understanding of brain function, synaptic plasticity, and dysfunction. These shortcomings in turn deter the ability to further design diagnostic, therapeutic strategies and the fabrication of neuro-modulatory devices with various feedback loop systems. We report here on the simulation and fabrication of fully configurable neural micro-electrodes that can be used for both in vitro and in vivo applications, with three-dimensional semi-insulated structures patterned onto custom, fine-pitch, high density arrays. These microelectrodes were interfaced with isolated brain slices as well as implanted in brains of freely behaving rats to demonstrate their ability to maintain a high SNR. Moreover, the electrodes enabled the detection of epileptiform events and high frequency oscillations in an epilepsy model thus offering a diagnostic potential for neurological disorders such as epilepsy. These microelectrodes provide unique opportunities to study brain activity under normal and various pathological conditions, both in-vivo and in in-vitro, thus furthering the ability to develop drug screening and neuromodulation systems that could accurately record and map the activity of large neural networks over an extended time period.

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Benchmarking miniaturized microscopy against two-photon calcium imaging using single-cell orientation tuning in mouse visual cortex

10.1101/494641 ◽

2018 ◽

Cited By ~ 1

Author(s):

Annet Glas ◽

Mark Huebener ◽

Tobias Bonhoeffer ◽

Pieter M Goltstein

Keyword(s):

Visual Cortex ◽

Calcium Imaging ◽

Visual Stimulation ◽

Signal To Noise Ratio ◽

Imaging Techniques ◽

Orientation Tuning ◽

Cell Orientation ◽

Two Photon ◽

Highly Correlated

Miniaturized microscopes are lightweight imaging devices that allow optical recordings from neurons in freely moving animals over the course of weeks. Despite their ubiquitous use, individual neuronal responses measured with these microscopes have not been directly compared to those obtained with established in vivo imaging techniques such as bench-top two-photon microscopes. To achieve this, we performed calcium imaging in mouse primary visual cortex while presenting animals with drifting gratings. We identified the same neurons in image stacks acquired with both microscopy methods and quantified orientation tuning of individual neurons. The response amplitude and signal-to-noise ratio of calcium transients recorded upon visual stimulation were highly correlated between both microscopy methods, although influenced by neuropil contamination in miniaturized microscopy. Tuning properties, calculated for individual orientation tuned neurons, were strongly correlated between imaging techniques. Thus, neuronal tuning features measured with a miniaturized microscope are quantitatively similar to those obtained with a two-photon microscope.

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

Visual Computing for Industry Biomedicine and Art ◽

10.1186/s42492-020-00067-5 ◽

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.

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Methods for Voltage-Sensitive Dye Imaging of Rat Cortical Activity With High Signal-to-Noise Ratio

Journal of Neurophysiology ◽

10.1152/jn.01169.2006 ◽

2007 ◽

Vol 98 (1) ◽

pp. 502-512 ◽

Cited By ~ 81

Author(s):

Michael T. Lippert ◽

Kentaroh Takagaki ◽

Weifeng Xu ◽

Xiaoying Huang ◽

Jian-Young Wu

Keyword(s):

Dynamic Range ◽

Signal To Noise Ratio ◽

Field Potential ◽

High Sensitivity ◽

High Dynamic Range ◽

High Signal ◽

Blue Dye ◽

Voltage Sensitive Dye ◽

Imaging Device

We describe methods to achieve high sensitivity in voltage-sensitive dye (VSD) imaging from rat barrel and visual cortices in vivo with the use of a blue dye RH1691 and a high dynamic range imaging device (photodiode array). With an improved staining protocol and an off-line procedure to remove pulsation artifact, the sensitivity of VSD recording is comparable with that of local field potential recording from the same location. With this sensitivity, one can record from ∼500 individual detectors, each covering an area of cortical tissue 160 μm in diameter (total imaging field ∼4 mm in diameter) and a temporal resolution of 1,600 frames/s, without multiple-trial averaging. We can record 80–100 trials of intermittent 10-s trials from each imaging field before the VSD signal reduces to one half of its initial amplitude because of bleaching and wash-out. Taken together, the methods described in this report provide a useful tool for visualizing evoked and spontaneous waves from rodent cortex.

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Rationally Designing Simple Rod-Like Amphiphilic NIR-Emissive AIE Probes for Precise In-Vivo Detection of Aβ Fibrils/Plaques at A Super-Early Stage

10.26434/chemrxiv.13699222.v1 ◽

2021 ◽

Author(s):

Yipu Wang ◽

Dong Mei ◽

Xinyi Zhang ◽

Da-Hui Qu ◽

Ju Mei ◽

...

Keyword(s):

High Performance ◽

Ex Vivo ◽

Early Stage ◽

Signal To Noise Ratio ◽

High Signal ◽

In Vivo Detection ◽

Different Strains ◽

Aβ Fibrils

With increase of social aging, Alzheimer's disease (AD) has been one of the serious diseases threatening human health. The occurrence of Aβ fibrils or plaques is recognized as the hallmark of AD. Currently, optical imaging has stood out to be a promising technique for the imaging of Aβ fibrils/plaques and the diagnosis of AD. However, restricted by their poor blood-brain barrier (BBB) penetrability, short-wavelength excitation and emission, and aggregation-caused quenching (ACQ) effect, the clinically used gold-standard optical probes such as <a>thioflavin</a> T (ThT) and thioflavin S (ThS), are not effective enough in the early diagnosis of AD in vivo. Herein, we put forward an “all-in-one” design principle and demonstrate its feasibility in developing high-performance fluorescent probes which are specific to Aβ fibrils/plaques and promising for super-early in-vivo diagnosis of AD. As a proof of concept, a simple rod-like amphiphilic NIR fluorescent AIEgen, i.e., AIE-CNPy-AD, is developed by taking the specificity, BBB penetration ability, deep-tissue penetration capacity, high signal-to-noise ratio (SNR) into consideration. AIE-CNPy-AD is constituted by connecting the electron-donating and accepting moieties through single bonds and tagging with a propanesulfonate tail, giving rise to the NIR fluorescence, aggregation-induced emission (AIE) effect, amphiphilicity, and rod-like structure, which in turn result in high binding-affinity and excellent specificity to Aβ fibrils/plaques, satisfactory ability to penetrate BBB and deep tissues, ultrahigh SNR and sensitivity, and high-fidelity imaging capability. In-vitro, ex-vivo, and in-vivo <a>identifying of Aβ fibrils/plaques</a> in different strains of mice indicate that AIE-CNPy-AD holds the universality to the detection of Aβ fibrils/plaques. It is noteworthy that AIE-CNPy-AD is even able to trace the small and sparsely distributed Aβ fibrils/plaques in very young AD model mice such as 4-month-old APP/PS1 mice which are reported to be the youngest mice to have Aβ deposits in brains, suggesting its great potential in diagnosis and intervention of AD at a super-early stage.

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Renal cell markers: lighthouses for managing renal diseases

AJP Renal Physiology ◽

10.1152/ajprenal.00182.2021 ◽

2021 ◽

Author(s):

Shivangi Agarwal ◽

Yashwanth R Sudhini ◽

Onur K Polat ◽

Jochen Reiser ◽

Mehmet Mete Altintas

Keyword(s):

High Efficiency ◽

Imaging Techniques ◽

Unmet Need ◽

Cell Types ◽

Whole Body ◽

Renal Diseases ◽

Cell Type ◽

Cell Markers ◽

Urine Production

Kidneys, one of the vital organs in our body, are responsible for maintaining whole-body homeostasis. The complexity of renal function (e.g., filtration, reabsorption, fluid and electrolyte regulation, urine production) demands diversity not only at the level of cell types but also in their overall distribution and structural framework within the kidney. To gain an in-depth molecular-level understanding of the renal system, it is imperative to discern the components of kidney and the types of cells residing in each of the sub-regions. Recent developments in labeling, tracing, and imaging techniques enabled us to mark, monitor and identify these cells in vivo with high efficiency in a minimally invasive manner. In this review, we have summarized different cell types, specific markers that are uniquely associated with those cell types, and their distribution in kidney, which altogether make kidneys so special and different. Cellular sorting based on the presence of certain proteins on the cell surface allowed for assignment of multiple markers for each cell type. However, different studies using different techniques have found contradictions in the cell-type specific markers. Thus, the term "cell marker" might be imprecise and sub-optimal, leading to uncertainty when interpreting the data. Therefore, we strongly believe that there is an unmet need to define the best cell markers for a cell type. Although, the compendium of renal-selective marker proteins presented in this review is a resource that may be useful to the researchers, we acknowledge that the list may not be necessarily exhaustive.

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Sequential average segmented microscopy for high signal-to-noise ratio motion-artifact-free in vivo heart imaging

Biomedical Optics Express ◽

10.1364/boe.4.002095 ◽

2013 ◽

Vol 4 (10) ◽

pp. 2095 ◽

Cited By ~ 12

Author(s):

Claudio Vinegoni ◽

Sungon Lee ◽

Paolo Fumene Feruglio ◽

Pasquina Marzola ◽

Matthias Nahrendorf ◽

...

Keyword(s):

Signal To Noise Ratio ◽

Motion Artifact ◽

High Signal ◽

Signal To Noise ◽

Heart Imaging ◽

Noise Ratio

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Targeted two-photon chemical apoptotic ablation of defined cell types in vivo

Nature Communications ◽

10.1038/ncomms15837 ◽

2017 ◽

Vol 8 (1) ◽

Cited By ~ 18

Author(s):

Robert A. Hill ◽

Eyiyemisi C. Damisah ◽

Fuyi Chen ◽

Alex C. Kwan ◽

Jaime Grutzendler

Keyword(s):

Cell Types ◽

Two Photon

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

Doklady Biochemistry and Biophysics ◽

10.1134/s1607672921020034 ◽

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.

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