scholarly journals An Autonomous Molecular Bioluminescent Reporter (AMBER) for voltage imaging in freely moving animals

2019 ◽  
Author(s):  
Prasanna Srinivasan ◽  
Nicole M Griffin ◽  
Pradeep Joshi ◽  
Dhananjay Thakur ◽  
Alex Nguyen-Le ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Social Behavior ◽  
Neural Activity ◽  
Fold Increase ◽  
High Signal ◽  
Metabolic Demand ◽  
Differential Signal ◽  
Exogenous Substrate ◽  
Freely Moving

1.AbstractGenetically encoded reporters have greatly increased our understanding of biology, especially in neuroscience. While fluorescent reporters have been widely used, photostability and phototoxicity have hindered their use in long-term experiments. Bioluminescence overcomes some of these challenges but requires the addition of an exogenous luciferin limiting its use. Using a modular approach we have engineered Autonomous Molecular BioluminEscent Reporter (AMBER), an indicator of membrane potential. Unlike other luciferase-luciferin bioluminescent systems, AMBER encodes the genes to express both the luciferase and luciferin. AMBER is a voltage-gated luciferase coupling the functionalities of the Ciona voltage-sensing domain (VSD) and bacterial luciferase, luxAB. When AMBER is co-expressed with the luciferin producing genes it reversibly switches the bioluminescent intensity as a function of membrane potential. Using biophysical and biochemical methods we show that AMBER modulates its enzymatic activity as a function of the membrane potential. AMBER shows several-fold increase in the luminescent (ΔL/L) signal upon switching from the off to on state when the cell is depolarized. In vivo expression of AMBER in C. elegans allowed detecting pharyngeal pumping action and mechanosensory neural activity from multiple worms simultaneously. AMBER reports neural activity of multiple animals at the same time and can be used in social behavior assays to elucidate the role of membrane potential underlying behavior.2.Significance StatementThere have been many exciting advances in the development of genetically encoded voltage indicators to monitor intracelluar voltage changes. Most sensors employ fluorescence, which requires external light, potentially causing photobleaching or overheating. Consequently, there has been interest in developing luminescence reporters. However, they require addition of an exogenous substrate to produce light intracellularly. Here, we engineered a genetically encoded bioluminescent voltage indicator, AMBER, which unlike other bioluminescent activity indicators, does not require addition of an exogenous substrate. AMBER allows a large differential signal, a high signal-to-noise ratio, and causes minimal metabolic demand on cells. We used AMBER to record voltage activity in freely-moving C. elegans, demonstrating that AMBER is a important new tool for monitoring neuronal activity during social behavior.

scholarly journals Self-Reset Image Sensor With a Signal-to-Noise Ratio Over 70 dB and Its Application to Brain Surface Imaging

2021 ◽  
Vol 15 ◽  
Author(s):  
Thanet Pakpuwadon ◽  
Kiyotaka Sasagawa ◽  
Mark Christian Guinto ◽  
Yasumi Ohta ◽  
Makito Haruta ◽  
...  
Keyword(s):  
Neural Activity ◽  
Signal To Noise Ratio ◽  
Image Sensor ◽  
Oxide Semiconductor ◽  
High Signal ◽  
Unstable State ◽  
Signal To Noise ◽  
Compact Size ◽  
Noise Ratio

In this study, we propose a complementary-metal-oxide-semiconductor (CMOS) image sensor with a self-resetting system demonstrating a high signal-to-noise ratio (SNR) to detect small intrinsic signals such as a hemodynamic reaction or neural activity in a mouse brain. The photodiode structure was modified from N-well/P-sub to P+/N-well/P-sub to increase the photodiode capacitance to reduce the number of self-resets required to decrease the unstable stage. Moreover, our new relay board was used for the first time. As a result, an effective SNR of over 70 dB was achieved within the same pixel size and fill factor. The unstable state was drastically reduced. Thus, we will be able to detect neural activity. With its compact size, this device has significant potential to become an intrinsic signal detector in freely moving animals. We also demonstrated in vivo imaging with image processing by removing additional noise from the self-reset operation.

scholarly journals All-optical imaging and patterned stimulation with a one-photon endoscope

2021 ◽  
Author(s):  
Jinyong Zhang ◽  
Ryan N Hughes ◽  
Namsoo Kim ◽  
Isabella P Fallon ◽  
Konstantin I bakhurin ◽  
...  
Keyword(s):  
Neural Activity ◽  
Calcium Imaging ◽  
Neural Circuit ◽  
Integrated System ◽  
Striatal Neurons ◽  
Indirect Pathway ◽  
Cellular Resolution ◽  
All Optical ◽  
Freely Moving

While in vivo calcium imaging makes it possible to record activity in defined neuronal populations with cellular resolution, optogenetics allows selective manipulation of neural activity. Recently, these two tools have been combined to stimulate and record neural activity at the same time, but current approaches often rely on two-photon microscopes that are difficult to use in freely moving animals. To address these limitations, we have developed a new integrated system combining a one-photon endoscope and a digital micromirror device for simultaneous calcium imaging and precise optogenetic photo-stimulation with near cellular resolution (Miniscope with All-optical Patterned Stimulation and Imaging, MAPSI). Using this highly portable system in freely moving mice, we were able to image striatal neurons from either the direct pathway or the indirect pathway while simultaneously activating any neuron of choice in the field of view, or to synthesize arbitrary spatiotemporal patterns of photo-stimulation. We could also select neurons based on their relationship with behavior and recreate the behavior by mimicking the natural neural activity with photo-stimulation. MAPSI thus provides a powerful tool for interrogation of neural circuit function in freely moving animals.

scholarly journals Chronically-implanted Neuropixels probes enable high yield recordings in freely moving mice

2018 ◽  
Author(s):  
A.L. Juavinett ◽  
G. Bekheet ◽  
A.K. Churchland
Keyword(s):  
Neural Activity ◽  
Neural Circuitry ◽  
High Yield ◽  
High Signal ◽  
Signal To Noise ◽  
Approaches To Studying ◽  
Freely Moving

AbstractThe advent of high-yield electrophysiology using Neuropixels probes is now enabling researchers to simultaneously record hundreds of neurons with remarkably high signal to noise. However, these probes have not been comprehensively tested in freely moving mice. It is critical to study neural activity in unrestricted animals, and the field would benefit from the inclusion of ethological approaches to studying the neural circuitry of behavior. We therefore adapted Neuropixels probes for chronically-implanted experiments in freely moving mice. We demonstrate the ease and utility of this approach in recording hundreds of neurons across weeks, and provide the methodological details for other researchers to do the same. Importantly, our approach enables researchers to explant and reuse these valuable probes.

scholarly journals Multifunctional optrode for opsin delivery, optical stimulation, and electrophysiological recordings in freely moving rats

2021 ◽  
Author(s):  
Kirti Sharma ◽  
Zoe Jaeckel ◽  
Artur Schneider ◽  
Oliver Paul ◽  
Ilka Diester ◽  
...  
Keyword(s):  
Neural Activity ◽  
Tissue Damage ◽  
Viral Vector ◽  
Microfluidic Channel ◽  
Neural Population ◽  
Total System ◽  
Electrophysiological Response ◽  
Optical Stimulation ◽  
Freely Moving

AbstractObjectiveOptogenetics involves delivery of light-sensitive opsins to the target brain region, as well as introduction of optical and electrical devices to manipulate and record neural activity, respectively, from the targeted neural population. Combining these functionalities in a single implantable device is of great importance for a precise investigation of neural networks while minimizing tissue damage.ApproachWe report on the development, characterization, and in vivo validation of a multifunctional optrode that combines a silicon-based neural probe with an integrated microfluidic channel, and an optical glass fiber in a compact assembly. The silicon probe comprises an 11-μm-wide fluidic channel and 32 recording electrodes (diameter 30 μm) on a tapered probe shank with a length, thickness, and maximum width of 7.5 mm, 50 μm, and 150 μm, respectively. The size and position of fluidic channels, electrodes, and optical fiber can be precisely tuned according to the in vivo application.Main resultsWith a total system weight of 0.97 g, our multifunctional optrode is suitable for chronic in vivo experiments requiring simultaneous drug delivery, optical stimulation, and neural recording. We demonstrate the utility of our device in optogenetics by injecting a viral vector carrying a ChR2-construct in the prefrontal cortex and subsequent photostimulation of the transfected neurons while recording neural activity from both the target and adjacent regions in a freely moving rat. Additionally, we demonstrate a pharmacological application of our device by injecting GABA antagonist bicuculline in an anesthetized rat brain and simultaneously recording the electrophysiological response.SignificanceOur triple-modality device enables a single-step optogenetic surgery. In comparison to conventional multi-step surgeries, our approach achieves higher spatial specificity while minimizing tissue damage.Graphical abstract

scholarly journals Chronically implanted Neuropixels probes enable high-yield recordings in freely moving mice

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Ashley L Juavinett ◽  
George Bekheet ◽  
Anne K Churchland
Keyword(s):  
Neural Activity ◽  
Neural Circuits ◽  
High Yield ◽  
High Signal ◽  
Signal To Noise ◽  
Novel Device ◽  
Approaches To Study ◽  
Freely Moving

The advent of high-yield electrophysiology using Neuropixels probes is now enabling researchers to simultaneously record hundreds of neurons with remarkably high signal to noise. However, these probes have not been well-suited to use in freely moving mice. It is critical to study neural activity in unrestricted animals for many reasons, such as leveraging ethological approaches to study neural circuits. We designed and implemented a novel device that allows Neuropixels probes to be customized for chronically implanted experiments in freely moving mice. We demonstrate the ease and utility of this approach in recording hundreds of neurons during an ethological behavior across weeks of experiments. We provide the technical drawings and procedures for other researchers to do the same. Importantly, our approach enables researchers to explant and reuse these valuable probes, a transformative step which has not been established for recordings with any type of chronically-implanted probe.

Plasminogen Activation In Vivo upon Intravenous Infusion of DDAVP

1992 ◽  
Vol 67 (01) ◽  
pp. 111-116 ◽  
Author(s):  
Marcel Levi ◽  
Jan Paul de Boer ◽  
Dorina Roem ◽  
Jan Wouter ten Cate ◽  
C Erik Hack
Keyword(s):  
Monoclonal Antibodies ◽  
Plasminogen Activator ◽  
Plasma Levels ◽  
Fold Increase ◽  
Fibrinolytic System ◽  
Plasminogen Activation ◽  
Plasminogen Activator Activity ◽  
Insight Into

SummaryInfusion of desamino-d-arginine vasopressin (DDAVP) results in an increase in plasma plasminogen activator activity. Whether this increase results in the generation of plasmin in vivo has never been established.A novel sensitive radioimmunoassay (RIA) for the measurement of the complex between plasmin and its main inhibitor α2 antiplasmin (PAP complex) was developed using monoclonal antibodies preferentially reacting with complexed and inactivated α2-antiplasmin and monoclonal antibodies against plasmin. The assay was validated in healthy volunteers and in patients with an activated fibrinolytic system.Infusion of DDAVP in a randomized placebo controlled crossover study resulted in all volunteers in a 6.6-fold increase in PAP complex, which was maximal between 15 and 30 min after the start of the infusion. Hereafter, plasma levels of PAP complex decreased with an apparent half-life of disappearance of about 120 min. Infusion of DDAVP did not induce generation of thrombin, as measured by plasma levels of prothrombin fragment F1+2 and thrombin-antithrombin III (TAT) complex.We conclude that the increase in plasminogen activator activity upon the infusion of DDAVP results in the in vivo generation of plasmin, in the absence of coagulation activation. Studying the DDAVP induced increase in PAP complex of patients with thromboembolic disease and a defective plasminogen activator response upon DDAVP may provide more insight into the role of the fibrinolytic system in the pathogenesis of thrombosis.

Tantalum Oxide Nanoparticles as Versatile Contrast Agents for X-ray Computed Tomography

2020 ◽  
Author(s):  
Shatadru Chakravarty ◽  
Jeremy Hix ◽  
Kaitlyn Wieweora ◽  
Maximilian Volk ◽  
Elizabeth Kenyon ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Contrast Agents ◽  
Mesoporous Silica Nanoparticles ◽  
Sol Gel ◽  
Tantalum Oxide ◽  
High Signal ◽  
Drug Delivery Vehicles ◽  
X Ray Computed

Here we describe the synthesis, characterization and in vitro and in vivo performance of a series of tantalum oxide (TaOx) based nanoparticles (NPs) for computed tomography (CT). Five distinct versions of 9-12 nm diameter silane coated TaOx nanocrystals (NCs) were fabricated by a sol-gel method with varying degrees of hydrophilicity and with or without fluorescence, with the highest reported Ta content to date (78%). Highly hydrophilic NCs were left bare and were evaluated in vivo in mice for micro-CT of full body vasculature, where following intravenous injection, TaOx NCs demonstrate high CT contrast, circulation in blood for ~ 3 h, and eventual accumulation in RES organs; and following injection locally in the mammary gland, where the full ductal tree structure can be clearly delineated. Partially hydrophilic NCs were encapsulated within mesoporous silica nanoparticles (MSNPs; TaOx@MSNPs) and hydrophobic NCs were encapsulated within poly(lactic-co-glycolic acid) (PLGA; TaOx@PLGA) NPs, serving as potential CT-imagable drug delivery vehicles. Bolus intramuscular injections of TaOx@PLGA NPs and TaOx@MSNPs to mimic the accumulation of NPs at a tumor site produce high signal enhancement in mice. In vitro studies on bare NCs and formuated NPs demonstrate high cytocompatibility and low dissolution of TaOx. This work solidifies that TaOx-based NPs are versatile contrast agents for CT.

Smartphone sensing of social interactions in people with and without schizophrenia

2020 ◽  
Author(s):  
Daniel Fulford ◽  
Jasmine Mote ◽  
Rachel Gonzalez ◽  
Samuel Abplanalp ◽  
Yuting Zhang ◽  
...  
Keyword(s):  
Social Behavior ◽  
Social Functioning ◽  
Social Activity ◽  
Network Size ◽  
Social Impairment ◽  
Schizophrenia Spectrum Disorders ◽  
Social Network Size ◽  
Digital Phenotyping ◽  
Ecological Momentary

Social impairment is a cardinal feature of schizophrenia spectrum disorders (SZ). Smaller social network size, diminished social skills, and loneliness are highly prevalent. Existing, gold-standard assessments of social impairment in SZ often rely on self-reported information that depends on retrospective recall and detailed accounts of complex social behaviors. This is particularly problematic in people with SZ given characteristic cognitive impairments and reduced insight. Ecological Momentary Assessment (EMA; repeated self-reports completed in the context of daily life) allows for the measurement of social behavior as it occurs in vivo, yet still relies on participant input. Momentary characterization of behavior using smartphone sensors (e.g., GPS, microphone) may also provide ecologically valid indicators of social functioning. In the current study we tested associations between both active (e.g., EMA-reported number of interactions) and passive (GPS-based mobility, conversations captured by microphone) smartphone-based measures of social activity and measures of social functioning and loneliness to examine the promise of such measures for understanding social impairment in SZ. Our results indicate that passive markers of mobility were more consistently associated with EMA measures of social behavior in controls than in people with SZ. Furthermore, dispositional loneliness showed associations with mobility metrics in both groups, while general social functioning was less related to these metrics. Finally, interactions detected in the ambient audio were more tied to social functioning in SZ than in controls. Findings speak to the promise of smartphone-based digital phenotyping as an approach to understanding objective markers of social activity in people with and without schizophrenia.

scholarly journals Hippocampal Interneurons are Required for Trace Eyeblink Conditioning in Mice

2021 ◽  
Author(s):  
Wei-Wei Zhang ◽  
Rong-Rong Li ◽  
Jie Zhang ◽  
Jie Yan ◽  
Qian-Hui Zhang ◽  
...  
Keyword(s):  
Eyeblink Conditioning ◽  
Pyramidal Cells ◽  
Conditioned Eyeblink ◽  
Cellular Mechanisms ◽  
Sustained Activity ◽  
Early Acquisition ◽  
Freely Moving ◽  
Trace Eyeblink Conditioning

AbstractWhile the hippocampus has been implicated in supporting the association among time-separated events, the underlying cellular mechanisms have not been fully clarified. Here, we combined in vivo multi-channel recording and optogenetics to investigate the activity of hippocampal interneurons in freely-moving mice performing a trace eyeblink conditioning (tEBC) task. We found that the hippocampal interneurons exhibited conditioned stimulus (CS)-evoked sustained activity, which predicted the performance of conditioned eyeblink responses (CRs) in the early acquisition of the tEBC. Consistent with this, greater proportions of hippocampal pyramidal cells showed CS-evoked decreased activity in the early acquisition of the tEBC. Moreover, optogenetic suppression of the sustained activity in hippocampal interneurons severely impaired acquisition of the tEBC. In contrast, suppression of the sustained activity of hippocampal interneurons had no effect on the performance of well-learned CRs. Our findings highlight the role of hippocampal interneurons in the tEBC, and point to a potential cellular mechanism subserving associative learning.

scholarly journals Hybrid Multisite Silicon Neural Probe with Integrated Flexible Connector for Interchangeable Packaging

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2605
Author(s):  
Ashley Novais ◽  
Carlos Calaza ◽  
José Fernandes ◽  
Helder Fonseca ◽  
Patricia Monteiro ◽  
...  
Keyword(s):  
Fabrication Process ◽  
High Signal ◽  
Wafer Level ◽  
Neural Probes ◽  
Insertion Force ◽  
Precise Integration ◽  
Flexible Cable ◽  
Flexible Polymer ◽  
Hybrid Silicon

Multisite neural probes are a fundamental tool to study brain function. Hybrid silicon/polymer neural probes combine rigid silicon and flexible polymer parts into one single device and allow, for example, the precise integration of complex probe geometries, such as multishank designs, with flexible biocompatible cabling. Despite these advantages and benefiting from highly reproducible fabrication methods on both silicon and polymer substrates, they have not been widely available. This paper presents the development, fabrication, characterization, and in vivo electrophysiological assessment of a hybrid multisite multishank silicon probe with a monolithically integrated polyimide flexible interconnect cable. The fabrication process was optimized at wafer level, and several neural probes with 64 gold electrode sites equally distributed along 8 shanks with an integrated 8 µm thick highly flexible polyimide interconnect cable were produced. The monolithic integration of the polyimide cable in the same fabrication process removed the necessity of the postfabrication bonding of the cable to the probe. This is the highest electrode site density and thinnest flexible cable ever reported for a hybrid silicon/polymer probe. Additionally, to avoid the time-consuming bonding of the probe to definitive packaging, the flexible cable was designed to terminate in a connector pad that can mate with commercial zero-insertion force (ZIF) connectors for electronics interfacing. This allows great experimental flexibility because interchangeable packaging can be used according to experimental demands. High-density distributed in vivo electrophysiological recordings were obtained from the hybrid neural probes with low intrinsic noise and high signal-to-noise ratio (SNR).

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