Tool In Neuroscience Research Research Articles

Inhibition of Na+/H+ exchanger modulates microglial activation and scar formation following microelectrode implantation

Objective. Intracortical microelectrodes are an important tool for neuroscience research and have great potential for clinical use. However, the use of microelectrode arrays to treat neurological disorders and control prosthetics is limited by biological challenges such as glial scarring, which can impair chronic recording performance. Microglia activation is an early and prominent contributor to glial scarring. After insertion of an intracortical microelectrode, nearby microglia transition into a state of activation, migrate, and encapsulate the device. Na+/H+ exchanger isoform-1 (NHE-1) is involved in various microglial functions, including their polarity and motility, and has been implicated in pro-inflammatory responses to tissue injury. HOE-642 (cariporide) is an inhibitor of NHE-1 and has been shown to depress microglial activation and inflammatory response in brain injury models. Approach. In this study, the effects of HOE-642 treatment on microglial interactions to intracortical microelectrodes was evaluated using two-photon microscopy in vivo. Main results. The rate at which microglia processes and soma migrate in response to electrode implantation was unaffected by HOE-642 administration. However, HOE-642 administration effectively reduced the radius of microglia activation at 72 h post-implantation from 222.2 µm to 177.9 µm. Furthermore, treatment with HOE-642 significantly reduced microglial encapsulation of implanted devices at 5 h post-insertion from 50.7 ± 6.0% to 8.9 ± 6.1%, which suggests an NHE-1-specific mechanism mediating microglia reactivity and gliosis during implantation injury. Significance. This study implicates NHE-1 as a potential target of interest in microglial reactivity and HOE-642 as a potential treatment to attenuate the glial response and scar formation around implanted intracortical microelectrodes.

Hematology and Culture Assessment of Cranially Implanted Rhesus Macaques (Macaca mulatta).

The use of percutaneous cranial implants in rhesus macaques (Macaca mulatta) has long been a valuable tool for neuroscience research. However, when treating and assessing these animals, veterinarians are required to make assumptions about diagnostic results due to a lack of research into how these implants affect physiology. Microbial cultures of cranial implant sites show an abundance of colonizing bacteria, but whether these microbes affect animal health and wellbeing is poorly understood. In addition, microbial antibiotic resistance can present significant health concerns for both the animals and the researchers. To help elucidate the relationship between percutaneous cranial implants and blood parameters, complete blood cell counts and serum chemistry results were assessed on 57 nonhuman primates at our institution from September 2001 to March 2017. Generalized estimating equations were used to compare the results before and after an animal's first implant surgery. This modelling showed that cranial implants were a significant predictor of alterations in the number of neutrophils, lymphocytes, and red blood cells, and in the concentration of hemoglobin, alkaline phosphatase, creatinine, calcium, phos- phorus, total protein, albumin, and globulin. Anaerobic and aerobic bacterial cultures were performed to identify bacteria associated with cranial implants. Staphylococcus spp., Streptococcus spp., and Corynebacterium spp. comprised the majority of the aerobic bacterial isolates, while Fusobacterium spp., Peptostreptococcus spp. and Bacterioides fragilis comprised the majority of anaerobic bacterial isolates. Using a Pearson r correlation for statistical analysis, we assessed whether any of these bacterial isolates developed antibiotic resistances over time. Cefazolin, the most frequently used antibiotic in monkeys in this study, was the only antimicrobial out of 41 agents tested to which bacteria developed resistance over time. These results indicate that percutaneous implants are associated with a generalized inflammatory state, multiple bacterial species are present at the implant site, and these bacteria may contribute to the inflammatory response.

Multimodal Functional Analysis Platform: 1. Ultrathin Fluorescence Endoscope Imaging System Enables Flexible Functional Brain Imaging.

To elucidate the expression mechanisms of brain functions, we have developed an ultrathin fluorescence endoscope imaging system (U-FEIS) that can image cells in the brain at any depth while minimizing the invasion. The endoscope part of U-FEIS consists of a GRIN lens and a 10,000-pixel image fiber with a diameter of 450μm. The specialized microscope of U-FEIS is within 30cm square and includes lenses and optical filters optimized for the endoscope. Using U-FEIS, we successfully visualized neurons expressing GFP with single-cell resolution and recorded the multineuronal activities in vitro and in vivo. U-FEIS can also perform imaging and optical stimulation simultaneously. Therefore, U-FEIS should be a powerful optical tool in neuroscience research.

Discovery of novel peptide neurotoxins from sea anemone species.

As primitive metazoa, sea anemones are rich in various bioactive peptide neurotoxins. These peptides have been applied to neuroscience research tools or directly developed as marine drugs. To date, more than 1100 species of sea anemones have been reported, but only 5% of the species have been used to isolate and identify sea anemone peptide neurotoxins. There is an urgent need for more systematic discovery and study of peptide neurotoxins in sea anemones. In this review, we have gathered the currently available methods from crude venom purification and gene cloning to venom multiomics, employing these techniques for discovering novel sea anemone peptide neurotoxins. In addition, the three-dimensional structures and targets of sea anemone peptide neurotoxins are summarized. Therefore, the purpose of this review is to provide a reference for the discovery, development, and utilization of sea anemone peptide neurotoxins.

Incorporating Neuroscience Data into Agent-Based Simulation Models of Buyer Behavior

Purpose: The article aims to analyze the possibility of using various cognitive neuroscience techniques when building the agent model of buyer behavior and propose an experimental procedure for obtaining qualitative data based on the triangulation of methods. Design/Methodology/Approach: The proposed approach combines agent-based simulation with cognitive neuroscience techniques at the stage of designing the characteristics and behavior rules of agents-consumers. Findings: The consumer’s purchasing behavior is determined by the compilation of the influence of environmental factors and marketing stimuli as well as by his personality traits. Due to the necessity to consider all these elements when mapping the consumer-agent characteristics and decision rules, traditional methods of data collection may not be sufficient. In such a situation, cognitive neuroscience techniques can become a source of additional information, allowing to take into account the influence of emotions or cognitive abilities on one’s decisions. To make it possible, it is necessary to conduct experiments with the use of neuroscience research tools (e.g., EEG, GSR, HR etc.) aimed at detecting emotional and cognitive states during exposure to an advertisement of a specific product. The neurophysiological data collected during the experiments allow for a more accurate estimation of the qualitative parameters describing consumer behavior rules. Practical Implications: The proposed concept allows for a more accurate representation of agents-consumers’ features and decision rules. Consequently, the agent-based model more reliably reflects reality, and thus the results obtained during model simulation are more valuable and can be the basis for formulating marketing plans. Originality/Value: The proposed approach enriches the methodology of data collection and estimation of qualitative parameters in building agent models of buyer behavior.

Decoding visual information from high-density diffuse optical tomography neuroimaging data

BackgroundNeural decoding could be useful in many ways, from serving as a neuroscience research tool to providing a means of augmented communication for patients with neurological conditions. However, applications of decoding are currently constrained by the limitations of traditional neuroimaging modalities. Electrocorticography requires invasive neurosurgery, magnetic resonance imaging (MRI) is too cumbersome for uses like daily communication, and alternatives like functional near-infrared spectroscopy (fNIRS) offer poor image quality. High-density diffuse optical tomography (HD-DOT) is an emerging modality that uses denser optode arrays than fNIRS to combine logistical advantages of optical neuroimaging with enhanced image quality. Despite the resulting promise of HD-DOT for facilitating field applications of neuroimaging, decoding of brain activity as measured by HD-DOT has yet to be evaluated. ObjectiveTo assess the feasibility and performance of decoding with HD-DOT in visual cortex. Methods and ResultsTo establish the feasibility of decoding at the single-trial level with HD-DOT, a template matching strategy was used to decode visual stimulus position. A receiver operating characteristic (ROC) analysis was used to quantify the sensitivity, specificity, and reproducibility of binary visual decoding. Mean areas under the curve (AUCs) greater than 0.97 across 10 imaging sessions in a highly sampled participant were observed. ROC analyses of decoding across 5 participants established both reproducibility in multiple individuals and the feasibility of inter-individual decoding (mean AUCs > 0.7), although decoding performance varied between individuals. Phase-encoded checkerboard stimuli were used to assess more complex, non-binary decoding with HD-DOT. Across 3 highly sampled participants, the phase of a 60° wide checkerboard wedge rotating 10° per second through 360° was decoded with a within-participant error of 25.8±24.7°. Decoding between participants was also feasible based on permutation-based significance testing. ConclusionsVisual stimulus information can be decoded accurately, reproducibly, and across a range of detail (for both binary and non-binary outcomes) at the single-trial level (without needing to block-average test data) using HD-DOT data. These results lay the foundation for future studies of more complex decoding with HD-DOT and applications in clinical populations.

Fabrication and modeling of recessed traces for silicon-based neural microelectrodes

Objective. Chronically-implanted neural microelectrodes are powerful tools for neuroscience research and emerging clinical applications, but their usefulness is limited by their tendency to fail after months in vivo. One failure mode is the degradation of insulation materials that protect the conductive traces from the saline environment. Approach. Studies have shown that material degradation is accelerated by mechanical stresses, which tend to concentrate on raised topographies such as conducting traces. Therefore, to avoid raised topographies, we developed a fabrication technique that recesses (buries) the traces in dry-etched, self-aligned trenches. Main results. The fabrication technique produced flatness within approximately 15 nm. Finite element modeling showed that the recessed geometry would be expected to reduce intrinsic stress concentrations in the insulation layers. Finally, in vitro electrochemical tests confirmed that recessed traces had robust recording and stimulation capabilities that were comparable to an established non-recessed device design. Significance. Our recessed trace fabrication technique requires no extra masks, is easy to integrate with existing processes, and is likely to improve the long-term performance of implantable neural devices.

Curses or Cures: A Review of the Numerous Benefits Versus the Biosecurity Concerns of Conotoxin Research.

Conotoxins form a diverse group of peptide toxins found in the venom of predatory marine cone snails. Decades of conotoxin research have provided numerous measurable scientific and societal benefits. These include their use as a drug, diagnostic agent, drug leads, and research tools in neuroscience, pharmacology, biochemistry, structural biology, and molecular evolution. Human envenomations by cone snails are rare but can be fatal. Death by envenomation is likely caused by a small set of toxins that induce muscle paralysis of the diaphragm, resulting in respiratory arrest. The potency of these toxins led to concerns regarding the potential development and use of conotoxins as biological weapons. To address this, various regulatory measures have been introduced that limit the use and access of conotoxins within the research community. Some of these regulations apply to all of the ≈200,000 conotoxins predicted to exist in nature of which less than 0.05% are estimated to have any significant toxicity in humans. In this review we provide an overview of the many benefits of conotoxin research, and contrast these to the perceived biosecurity concerns of conotoxins and research thereof.

Cortical Hemodynamic Response to Multi-afferent Stimulation: an optical imaging study.

Multisensory stimulation plays an important role in the recovery of ischemic stroke. However, little is known about the interactions between neuronal activities with multi-afferent stimulations and their effects on hemodynamic responses. Optogenetics has been a useful tool in neuroscience research to unravel the mechanisms of neurovascular coupling at cell-specific level. In this study, we applied laser speckle contrast imaging (LSCI) to map the cortical hemodynamic response with high spatiotemporal resolution. The results showed that optogenetic inhibition of pyramidal neurons in sensorimotor cortex induced both local and distant increases of cerebral blood flow (CBF) with dual peaks, and the full width at half maximum (FWHM) was significantly larger than that of the CBF response to optogenetic excitation. Furthermore, optogenetic excitation of pyramidal neurons could significantly increase the local CBF response to sensory stimulation, whereas optogenetic inhibition of pyramidal neurons decreased the local CBF response at the early stage after sensory stimulation and increased the distant CBF response during the recovery period. Our work provided useful insights into the mechanisms of brain stimulation, which might help in clinical neurological applications.

3D-Printed Soft Lithography for Complex Compartmentalized Microfluidic Neural Devices.

Compartmentalized microfluidic platforms are an invaluable tool in neuroscience research. However, harnessing the full potential of this technology remains hindered by the lack of a simple fabrication approach for the creation of intricate device architectures with high‐aspect ratio features. Here, a hybrid additive manufacturing approach is presented for the fabrication of open‐well compartmentalized neural devices that provides larger freedom of device design, removes the need for manual postprocessing, and allows an increase in the biocompatibility of the system. Suitability of the method for multimaterial integration allows to tailor the device architecture for the long‐term maintenance of healthy human stem‐cell derived neurons and astrocytes, spanning at least 40 days. Leveraging fast‐prototyping capabilities at both micro and macroscale, a proof‐of‐principle human in vitro model of the nigrostriatal pathway is created. By presenting a route for novel materials and unique architectures in microfluidic systems, the method provides new possibilities in biological research beyond neuroscience applications.

A Highly Sensitive Amperometric Glutamate Oxidase Microbiosensor Based on a Reduced Graphene Oxide/Prussian Blue Nanocube/Gold Nanoparticle Composite Film-Modified Pt Electrode.

A simple method that relies only on an electrochemical workstation has been investigated to fabricate a highly sensitive glutamate microbiosensor for potential neuroscience applications. In this study, in order to develop the highly sensitive glutamate electrode, a 100 µm platinum wire was modified by the electrochemical deposition of gold nanoparticles, Prussian blue nanocubes, and reduced graphene oxide sheets, which increased the electroactive surface area; and the chitosan layer, which provided a suitable environment to bond the glutamate oxidase. The optimization of the fabrication procedure and analytical conditions is described. The modified electrode was characterized using field emission scanning electron microscopy, impedance spectroscopy, and cyclic voltammetry. The results exhibited its excellent sensitivity for glutamate detection (LOD = 41.33 nM), adequate linearity (50 nM–40 µM), ascendant reproducibility (RSD = 4.44%), and prolonged stability (more than 30 repetitive potential sweeps, two-week lifespan). Because of the important role of glutamate in neurotransmission and brain function, this small-dimension, high-sensitivity glutamate electrode is a promising tool in neuroscience research.

Divergent Findings in Brain Reorganization After Spinal Cord Injury: A Review.

Spinal cord injury (SCI) leads to a general lack of sensory and motor functions below the level of injury and may promote deafferentation-induced brain reorganization. Functional magnetic resonance imaging (fMRI) has been established as an essential tool in neuroscience research and can precisely map the spatiotemporal distribution of brain activity. Task-based fMRI experiments associated with the tongue, upper limbs, or lower limbs have been used as the primary paradigms to study brain reorganization following SCI. A review of the current literature on the subject shows one common trait: while most articles agree that brain networks are usually preserved after SCI, and that is not the case as some articles describe possible alterations in brain activation after the lesion. There is no consensus if those alterations indeed occur. In articles that show alterations, there is no agreement if they are transient or permanent. Besides, there is no consensus on which areas are most prone to activation changes, or on the intensity and direction (increase vs. decrease) of those possible changes. In this article, we present a critical review of the literature and trace possible reasons for those contradictory findings on brain reorganization following SCI. fMRI studies based on the ankle dorsiflexion, upper-limb, and tongue paradigms are used as case studies for the analyses.

MEDUSA: A Low-Cost, 16-Channel Neuromodulation Platform with Arbitrary Waveform Generation

Neural stimulation systems are used to modulate electrically excitable tissue to interrogate neural circuit function or provide therapeutic benefit. Conventional stimulation systems are expensive and limited in functionality to standard stimulation waveforms, and they are bad for high frequency stimulation. We present MEDUSA, a system that enables new research applications that can leverage multi-channel, arbitrary stimulation waveforms. MEDUSA is low cost and uses commercially available components for widespread adoption. MEDUSA is comprised of a PC interface, an FPGA for precise timing control, and eight bipolar current sources that can each address up to 16 electrodes. The current sources have a resolution of 15.3 nA and can provide ±5 mA with ±5 V compliance. We demonstrate charge-balancing techniques in vitro using a custom microelectrode. An in vivo strength-duration curve for earthworm nerve activation is also constructed using MEDUSA. MEDUSA is a multi-functional neuroscience research tool for electroplating microelectrodes, performing electrical impedance spectroscopy, and examining novel neural stimulation protocols.

High-resolution T2-FLAIR and non-contrast CT brain atlas of the elderly

Normative brain atlases are a standard tool for neuroscience research and are, for example, used for spatial normalization of image datasets prior to voxel-based analyses of brain morphology and function. Although many different atlases are publicly available, they are usually biased with respect to an imaging modality and the age distribution. Both effects are well known to negatively impact the accuracy and reliability of the spatial normalization process using non-linear image registration methods. An important and very active neuroscience area that lacks appropriate atlases is lesion-related research in elderly populations (e.g. stroke, multiple sclerosis) for which FLAIR MRI and non-contrast CT are often the clinical imaging modalities of choice. To overcome the lack of atlases for these tasks and modalities, this paper presents high-resolution, age-specific FLAIR and non-contrast CT atlases of the elderly generated using clinical images.

Rational Design of a Near-infrared Fluorescence Probe for Ca2+ Based on Phosphorus-substituted Rhodamines Utilizing Photoinduced Electron Transfer.

Fluorescence imaging in the near-infrared (NIR) region (650-900 nm) is useful for bioimaging because background autofluorescence is low and tissue penetration is high in this range. In addition, NIR fluorescence is useful as a complementary color window to green and red for multicolor imaging. Here, we compared the photoinduced electron transfer (PeT)-mediated fluorescence quenching of silicon- and phosphorus-substituted rhodamines (SiRs and PRs) in order to guide the development of improved far-red to NIR fluorescent dyes. The results of density functional theory calculations and photophysical evaluation of a series of newly synthesized PRs confirmed that the fluorescence of PRs was more susceptible than that of SiRs to quenching via PeT. Based on this, we designed and synthesized a NIR fluorescence probe for Ca2+ , CaPR-1, and its membrane-permeable acetoxymethyl derivative, CaPR-1 AM, which is distributed to the cytosol, in marked contrast to our previously reported Ca2+ far-red to NIR fluorescence probe based on the SiR scaffold, CaSiR-1 AM, which is mainly localized in lysosomes as well as cytosol in living cells. CaPR-1 showed longer-wavelength absorption and emission (up to 712 nm) than CaSiR-1. The new probe was able to image Ca2+ at dendrites and spines in brain slices, and should be a useful tool in neuroscience research.

Of Man and Mice: Translational Research in Neurotechnology

Emerging technological developments in nano- and microsystems engineering have delivered powerful tools for neuroscience research over the last 50 years. However, only a few neural implants have been transferred into clinical practice. Challenges and opportunities for translational research are discussed herein.

Real-time cortical simulation on neuromorphic hardware.

Real-time simulation of a large-scale biologically representative spiking neural network is presented, through the use of a heterogeneous parallelization scheme and SpiNNaker neuromorphic hardware. A published cortical microcircuit model is used as a benchmark test case, representing ≈1 mm2 of early sensory cortex, containing 77 k neurons and 0.3 billion synapses. This is the first hard real-time simulation of this model, with 10 s of biological simulation time executed in 10 s wall-clock time. This surpasses best-published efforts on HPC neural simulators (3 × slowdown) and GPUs running optimized spiking neural network (SNN) libraries (2 × slowdown). Furthermore, the presented approach indicates that real-time processing can be maintained with increasing SNN size, breaking the communication barrier incurred by traditional computing machinery. Model results are compared to an established HPC simulator baseline to verify simulation correctness, comparing well across a range of statistical measures. Energy to solution and energy per synaptic event are also reported, demonstrating that the relatively low-tech SpiNNaker processors achieve a 10 × reduction in energy relative to modern HPC systems, and comparable energy consumption to modern GPUs. Finally, system robustness is demonstrated through multiple 12 h simulations of the cortical microcircuit, each simulating 12 h of biological time, and demonstrating the potential of neuromorphic hardware as a neuroscience research tool for studying complex spiking neural networks over extended time periods.This article is part of the theme issue ‘Harmonizing energy-autonomous computing and intelligence’.

Electrochemical Evaluation of Layer-by-Layer Drug Delivery Coating for Neural Interfaces.

Intracortical microelectrode arrays (MEAs) are valuable tools for neuroscience research, and their potential clinical use has been demonstrated. However, their inability to function reliably over chronic time points has limited their clinical translation. MEA failure is highly correlated with foreign body response (FBR), and therapeutics have been used to reduce FBR and improve device function, with drugs such as minocycline showing promising results in vivo. To avoid issues associated with systemic drug delivery, device coatings can be used to for therapeutic delivery. One method to locally deliver minocycline is a layer-by-layer (LBL) coating that consists of multiple trilayers of gelatin type A, minocycline, and dextran sulfate; however, the coating's impact on device function was previously unknown. This work characterized 10, 20, and 30 trilayer coatings and then evaluated their effect on device function. Cumulative minocycline release and coating thickness increased with the number of trilayers, agreeing with observations in previous studies. Atomic force microscopy images were used to calculate surface roughness of the coatings, which significantly increased from 10 to 20 trilayers and then remained relatively constant upon increasing to 30 trilayers. Scanning electron microscopy images confirmed that trilayers coated the MEAs. Electrochemical impedance spectroscopy (EIS) and charge carrying capacity (CCC) were used to evaluate the coating's effect on MEA electrochemical behavior over 3 weeks while the coated MEAs soaked in PBS. The 10 trilayer coatings slightly decreased CCC, while 20 and 30 trilayers initially increased CCC. CCC of all trilayers gradually increased as the MEAs soaked in PBS. All trilayers initially increased MEA impedance magnitude and reduced the phase angle at low frequencies. Impedance magnitude at 1 kHz and 15 kHz decreased toward their initial precoated values for all trilayers as the MEAs soaked in PBS. Overall, these results show that the LBL coatings did not significantly impact MEA function.

An optimized method for neuronal differentiation of embryonic stem cells in vitro

BackgroundNeural differentiation from embryonic stem cells (ESCs) is an excellent model for elucidating the key mechanisms involved in neurogenesis, and also provides an unlimited source of progenitors for cell-based nerve regeneration. However, the existing protocols such as small molecule substances, 3D matrix, co-culture technique and transgenic method, are complicated and difficult to operate, thus are limited by laboratory conditions. Looking for an easy-to-operate protocol with easily gained material and high induction efficiency has always been a hot issue in neuroscience research. New methodsThis paper established an optimized method for embryonic neurogenesis using a strategy of "combinatorial screening". In our study, the whole process of embryonic neurogenesis was divided into two phases, and the differentiation efficiency of seven experimental protocols in phase I and three protocols in phase II were systematically evaluated in A2lox and 129 ESCs. ResultsIn phase I differentiation, "2-day embryoid bodies formation + 6-day retinoic acid induction" (Phase I-protocol 3) could effectively induce the differentiation of ESCs into neural precursor cells (NPCs). Furthermore, in phase II, N2B27 medium II (Phase II-protocol 3) could better support the subsequent differentiation from NPCs into neurons. Comparison with existing method(s)Such a combinational method (phase I-protocol 3 and phase II-protocol 3) can realize embryonic neurogenesis with high efficiency, easy implementation and low-cost, and is suitable for promotion in most laboratories. ConclusionsThrough "combinatorial screening" strategy, we established an optimized method for embryonic neurogenesis in vitro, which is expected to be a powerful tool for neuroscience research.

Knock-In Rat Lines with Cre Recombinase at the Dopamine D1 and Adenosine 2a Receptor Loci.

Genetically modified mice have become standard tools in neuroscience research. Our understanding of the basal ganglia in particular has been greatly assisted by BAC mutants with selective transgene expression in striatal neurons forming the direct or indirect pathways. However, for more sophisticated behavioral tasks and larger intracranial implants, rat models are preferred. Furthermore, BAC lines can show variable expression patterns depending upon genomic insertion site. We therefore used CRISPR/Cas9 to generate two novel knock-in rat lines specifically encoding Cre recombinase immediately after the dopamine D1 receptor (Drd1a) or adenosine 2a receptor (Adora2a) loci. Here, we validate these lines using in situ hybridization and viral vector mediated transfection to demonstrate selective, functional Cre expression in the striatal direct and indirect pathways, respectively. We used whole-genome sequencing to confirm the lack of off-target effects and established that both rat lines have normal locomotor activity and learning in simple instrumental and Pavlovian tasks. We expect these new D1-Cre and A2a-Cre rat lines will be widely used to study both normal brain functions and neurological and psychiatric pathophysiology.