Current Burst Research Articles

Community Integration of Disability: A Bibliometric and Knowledge-Map Analysis.

Community integration (CI) is the ultimate goal of rehabilitation for individuals with disabilities. It plays a significant role in restoring their social functioning and facilitating their reintegration into community and family life. However, no studies have utilized bibliometric methods to explore community integration. To conduct a review about community integration of disabilities and to clarify the knowledge, hotspots, and trends through the bibliometric method. Studies on community integration from 1990 to 2023 were retrieved from the Web of Science Core Collection (WOSCC). CiteSpace 6.2.R4 and Microsoft Office Excel 2019 were applied. The CiteSpace node types involved in this study include keyword, reference, cited author, cited Journal, and the dual-map overlay of journals. CiteSpace presented the keyword cluster map, keywords timeline view map, keywords bursts map, and overlay map of journals. Microsoft Office Excel 2019 was used to present the trend of annual publications and draw up related tables and figures. A total of 2239hits were included. The number of publications related to community integration is increasing gradually. The three most frequent keywords is Brain Injury (571, 13%), Individuals (488, 11%), Quality of Life (434, 10%). Keyword cluster map and timeline map with eight clusters were obtained, and the current strongest citation burst keywords are social participation, substance use, experiences, interventions, and Afghanistan. Willer is the author with the most citations. McColl has the largest centrality in the first ten cited authors. The most cited reference is published by the World Health Organization (WHO). Archives of Physical Medicine and Rehabilitation is the journal with the highest co-citation frequency. The overlay map of journals presented four distinct paths: the journals in "psychology education, health" and "neurology, sports, ophthalmology" often cite journals in "health, nursing, medicine" and "psychology, education, social". Community integration for individuals with disabilities is gradually becoming a hot topic. Research on community integration related to traumatic brain injury (TBI), stroke, children, and spinal cord injuries is current focus of community integration. Future research should explore the experiences and feelings of different groups of disabilities regarding community integration and develop more effective interventions for their community integration. Community integration is complex, and future research on community integration for individuals with disabilities needs to be explored more specifically.

Turbulent features of nearshore wave–current flow

Abstract. Waves and currents influence nearly all nearshore physical processes. Their complex interaction gives birth to complex turbulence features that are far from being completely understood. In this regard, previous studies mainly focused on mean flow or inferred turbulent features from averaged velocities, seldom examining turbulent fluctuations. Moreover, the dynamics of wave–current flow have mostly been replicated in experimental channel setups, i.e., overlooking the natural occurrence of waves and longshore currents intersecting at a near-orthogonal angle. In the present work, the hydrodynamics of near-orthogonal wave–current interaction are investigated through a physical model study. Experiments were carried out in a laboratory basin in the presence of fixed sand and gravel beds, where current-only, wave-only, and combined flow tests were performed. Flow velocities were measured by means of acoustic Doppler velocimeters, through which time-averaged, phase-averaged, and turbulent velocities were obtained. Results revealed two main features of the wave–current flow. First, we observed that the superposition of waves does not necessarily induce an increase in the current bed shear stresses. Indeed, depending on bed roughness, current freestream velocity and wave orbital velocity, enhancements or reductions of the current bed shear were observed. Moreover, application of quadrant analysis revealed a periodic evolution of the current turbulent bursts. Specifically, the number of current turbulent ejections and sweeps is reduced or increased as the wave phase progresses from antinodes to nodes and from nodes to antinodes, respectively.

Latent characterization of the complete BATSE gamma-ray bursts catalogue using Gaussian mixture of factor analysers and model-estimated overlap-based syncytial clustering

ABSTRACT Characterizing and distinguishing gamma-ray bursts (GRBs) has interested astronomers for many decades. While some authors have found two or three groups of GRBs by analysing only a few parameters, recent work identified five ellipsoidally shaped groups upon considering nine parameters $T_{50}, T_{90}, F_1, F_2, F_3, F_4, P_{64}, P_{256}, P_{1024}$. Yet others suggest subclasses within the two or three groups found earlier. Using a mixture model of Gaussian factor analysers, we analysed 1150 GRBs, that had nine parameters observed, from the current Burst and Transient Source Experiment (BATSE) catalogue, and again established five ellipsoidal-shaped groups to describe the GRBs. These five groups are characterized in terms of their average duration, fluence, and spectrum as shorter-faint-hard, long-intermediate-soft, long-intermediate-intermediate, long-bright-intermediate, and short-faint-hard. The use of factor analysers in describing individual group densities allows for a more thorough group-wise characterization of the parameters in terms of a few latent features. However, given the discrepancy with many other existing studies that advocated for two or three groups, we also performed model-estimated overlap-based syncytial clustering that successively merges poorer separated groups. The five ellipsoidal groups merge into three and then into two groups, one with GRBs of low durations and the other having longer duration GRBs. These groups are also characterized in terms of a few latent factors made up of the nine parameters. Our analysis provides context for all three sets of results, and in doing so, details a multilayered characterization of the BATSE GRBs, while also explaining the structure in their variability.

Study protocol for identifying resting brain functional connectivity markers of response to continuous Theta Burst Stimulation and cathodal transcranial Direct Current Stimulation in patients with schizophrenia with persistent auditory hallucinations

Background Schizophrenia is one of the most burdensome psychiatric disorders. Novel neuromodulatory techniques including cathodal transcranial direct current stimulation (c-tDCS) and continuous theta burst stimulation (cTBS) using repetitive transcranial magnetic stimulation (rTMS) are increasingly being used in alleviating the auditory verbal hallucinations that are persisting despite adequate antipsychotic treatment. Brain connectivity modulation by stimulating the left temporoparietal junction is thought to mediate these effects. The differential neurobiological mechanisms and efficacy of these two neuromodulation techniques are not known. We are unaware of any systematic studies that can guide clinicians in choosing between the two techniques. This protocol describes a parallel-arm, double-blind, randomized cross-over study to identify resting brain functional connectivity markers of response to cTBS and c-tDCS persistent auditory hallucinations to improve the efficacy of interventions. Methods Two hundred and ten consenting patients with schizophrenia with persistent auditory hallucinations will be randomly assigned to receive 15 days (30 sessions) of c-tDCS+sham-TBS or sham-tDCS+cTBS over the left temporoparietal region at three study centres. After a gap of 2-4 weeks, non-responders to the intervention will cross-over to the other arm. Clinical assessments, neurocognitive assessments, and multimodal investigations (magnetic resonance imaging, electroencephalography, heart rate variability, investigative transcranial magnetic stimulation-transcranial direct current stimulation, gene polymorphisms) will be conducted at baseline and repeated after the end of both phases of the trial. A differential pre-treatment resting brain functional connectivity signal will identify responders to cTBS or c-tDCS. Registration Clinical Trial Registry of India (CTRI/2021/05/033783) registered on 25/05/2021.

First-in-human demonstration of floating EMG sensors and stimulators wirelessly powered and operated by volume conduction

BackgroundRecently we reported the design and evaluation of floating semi-implantable devices that receive power from and bidirectionally communicate with an external system using coupling by volume conduction. The approach, of which the semi-implantable devices are proof-of-concept prototypes, may overcome some limitations presented by existing neuroprostheses, especially those related to implant size and deployment, as the implants avoid bulky components and can be developed as threadlike devices. Here, it is reported the first-in-human acute demonstration of these devices for electromyography (EMG) sensing and electrical stimulation.MethodsA proof-of-concept device, consisting of implantable thin-film electrodes and a nonimplantable miniature electronic circuit connected to them, was deployed in the upper or lower limb of six healthy participants. Two external electrodes were strapped around the limb and were connected to the external system which delivered high frequency current bursts. Within these bursts, 13 commands were modulated to communicate with the implant.ResultsFour devices were deployed in the biceps brachii and the gastrocnemius medialis muscles, and the external system was able to power and communicate with them. Limitations regarding insertion and communication speed are reported. Sensing and stimulation parameters were configured from the external system. In one participant, electrical stimulation and EMG acquisition assays were performed, demonstrating the feasibility of the approach to power and communicate with the floating device.ConclusionsThis is the first-in-human demonstration of EMG sensors and electrical stimulators powered and operated by volume conduction. These proof-of-concept devices can be miniaturized using current microelectronic technologies, enabling fully implantable networked neuroprosthetics.

Transcriptional bursting dynamics in gene expression.

Gene transcription is a stochastic process that occurs in all organisms. Transcriptional bursting, a critical molecular dynamics mechanism, creates significant heterogeneity in mRNA and protein levels. This heterogeneity drives cellular phenotypic diversity. Currently, the lack of a comprehensive quantitative model limits the research on transcriptional bursting. This review examines various gene expression models and compares their strengths and weaknesses to guide researchers in selecting the most suitable model for their research context. We also provide a detailed summary of the key metrics related to transcriptional bursting. We compared the temporal dynamics of transcriptional bursting across species and the molecular mechanisms influencing these bursts, and highlighted the spatiotemporal patterns of gene expression differences by utilizing metrics such as burst size and burst frequency. We summarized the strategies for modeling gene expression from both biostatistical and biochemical reaction network perspectives. Single-cell sequencing data and integrated multiomics approaches drive our exploration of cutting-edge trends in transcriptional bursting mechanisms. Moreover, we examined classical methods for parameter estimation that help capture dynamic parameters in gene expression data, assessing their merits and limitations to facilitate optimal parameter estimation. Our comprehensive summary and review of the current transcriptional burst dynamics theories provide deeper insights for promoting research on the nature of cell processes, cell fate determination, and cancer diagnosis.

From inception to innovation: bibliometric analysis of the evolution, hotspots, and trends in implantable collamer lens surgery research.

As one of several refractive surgeries, Implant Collamer Lens (ICL) surgery offers stable biocompatibility and consistent, high-quality visual outcomes. ICL has become an effective complement to corneal refractive surgery, gradually becoming one of the mainstream methods for correcting refractive errors. This study employs bibliometric methods to analyze research on ICL surgery to understand the progress, hotspots, and potential future trends in this field. This study performed a bibliometric analysis of all ICL-related articles collected from the Web of Science Core Collection database between January 1st, 1996, and December 31st, 2023. The CiteSpace 6.2.R4 tool, Excel and the Web of Science website were used to analyze data by country, institution, keywords, and clusters of keywords. Additionally, an in-depth interpretation and analysis were conducted on the field's high-impact articles. Since the first clinical application report of ICL, there have been a total of 875 studies. The number of papers published annually has shown an overall increasing trend. Studies published from China are the most numerous, accounting for 29.14% (n = 255) of the total. Among the institutions, Fudan University and Kitasato University both have published more than 50 papers, with Kitasato University having the highest H-index of 26. The journals with the top 10 publication volumes are all specialized in ophthalmology. The burst keywords since the introduction of ICL surgery have been "intraocular lens," "refractive surgery," and "cataract surgery." The current burst keywords include "visual quality," "vector analysis," "axial length," etc. The results of keyword clustering included ICL, pIOL, high myopia, axial length, optical quality, refractive surgery, ICL implantation, and pupil size. In the High-impact Articles, it was found that the high-impact articles predominantly focus on the safety, efficacy, and predictability of ICL surgery. Research on ICL has grown since its clinical introduction, with the advent of the central hole ICL sparking a surge in recent hotspots, particularly in China. Current hotpots in the field of ICL surgery are "visual quality," "ICL implantation," "vector analysis," "axial length," "evo ICL," "ICL v4c," and "ICL." ICL surgery research trends have evolved from implantation techniques to biological parameters associated with ICL surgery and the benefits of new ICL designs.

Transcranial burst electrical stimulation contributes to neuromodulatory effects in the rat motor cortex.

Transcranial Burst Electrical Stimulation (tBES) is an innovative non-invasive brain stimulation technique that combines direct current (DC) and theta burst stimulation (TBS) for brain neuromodulation. It has been suggested that the tBES protocol may efficiently induce neuroplasticity. However, few studies have systematically tested neuromodulatory effects and underlying neurophysiological mechanisms by manipulating the polarity of DC and TBS patterns. This study aimed to develop the platform and assess neuromodulatory effects and neuronal activity changes following tBES. Five groups of rats were exposed to anodal DC combined with intermittent TBS (tBES+), cathodal DC combined with continuous TBS (tBES-), anodal and cathodal transcranial direct current stimulation (tDCS+ and tDCS-), and sham groups. The neuromodulatory effects of each stimulation on motor cortical excitability were analyzed by motor-evoked potentials (MEPs) changes. We also investigated the effects of tBES on both excitatory and inhibitory neural biomarkers. We specifically examined c-Fos and glutamic acid decarboxylase (GAD-65) using immunohistochemistry staining techniques. Additionally, we evaluated the safety of tBES by analyzing glial fibrillary acidic protein (GFAP) expression. Our findings demonstrated significant impacts of tBES on motor cortical excitability up to 30 min post-stimulation. Specifically, MEPs significantly increased after tBES (+) compared to pre-stimulation (p = 0.026) and sham condition (p = 0.025). Conversely, tBES (-) led to a notable decrease in MEPs relative to baseline (p = 0.04) and sham condition (p = 0.048). Although tBES showed a more favorable neuromodulatory effect than tDCS, statistical analysis revealed no significant differences between these two groups (p > 0.05). Additionally, tBES (+) exhibited a significant activation of excitatory neurons, indicated by increased c-Fos expression (p < 0.05), and a reduction in GAD-65 density (p < 0.05). tBES (-) promoted GAD-65 expression (p < 0.05) while inhibiting c-Fos activation (p < 0.05), suggesting the involvement of cortical inhibition with tBES (-). The expression of GFAP showed no significant difference between tBES and sham conditions (p > 0.05), indicating that tBES did not induce neural injury in the stimulated regions. Our study indicates that tBES effectively modulates motor cortical excitability. This research significantly contributes to a better understanding of the neuromodulatory effects of tBES, and could provide valuable evidence for its potential clinical applications in treating neurological disorders.

A dynamic study of the postoperative management of thyroid cancer from 2003 to 2022: a bibliometric analysis.

Over the past 20 years, the global incidence of thyroid cancer has continued to increase. The volume of literature on the postoperative management of thyroid cancer comprises 1,040 articles, from 64 countries, with 1,400 journals publishing the relevant literature, and several guidelines on the treatment of thyroid cancer. This study used bibliometric methods to identify research hotspots and explore future directions in this field. We comprehensively searched the Science Citation Index Expanded (SCI-E) database of the Web of Science Core Collection (WOSCC) for articles published from 2003 to 2022 on the postoperative management of thyroid cancer. Using CiteSpace 6.1.R6 and Microsoft Office Excel 2010, we evaluated and visualized the search results. Using R Studio, we generated a network of spatial geographic distribution maps and cooperative network. A total of 1,040 publications were included in the study. The results revealed an overall upward trend in the number of publications and citations over the past 20 years. The United States of America (USA) had the largest number of publications and the highest centrality (n=282, centrality =0.28). Johns Hopkins University had highest centrality (centrality =0.15) and was the academic center of the field. Thyroid was the journal with the highest number of citations (n=826), and the American Journal of Surgical Pathology was the journal with the highest centrality (centrality =0.08). The top 10 citations in the literature were mainly guidelines and consensus statements on the management of thyroid cancer. A keyword-based clustering analysis revealed the prominence of clusters of keywords, such as follow-up, recurrent laryngeal nerve, and medullary thyroid carcinoma (MTC). A keyword burst detection analysis showed that the term papillary had the highest burst intensity (strength =8.02), while management guidelines, association guidelines, active surveillance (AS), microcarcinoma, and differentiated thyroid cancer were the current burst words. Over the past two decades, the number of relevant publications in the postoperative management of thyroid cancer field has continued to grow. Among the many research directions, follow-up, recurrent laryngeal nerve, and MTC are research hotspots. Future research is likely to revolve around guidelines and consensus statements on the management of thyroid cancer, AS, and microcarcinoma in differentiated thyroid cancer.

On molecular steps that activate a voltage sensitive ion channel at critical depolarization

At high transmembrane electric field, a voltage sensitive ion channel is an insulator; when the field is critically reduced, it becomes a conductor of selected ions. The Channel Activation by Electrostatic Repulsion (CAbER) hypothesis proposes that an ordered polarization field of induced dipoles at the high electric field magnitude of the excitable state is overcome by thermal disorder at a critical depolarization. Increased repulsions between positive charges in the S4 segments cause an allosteric transition in which these segments expand and separate in a chiral proteinquake. The increased space allows the P segments to refold and the ion-semiconducting S5 and S6 segments to relax and expand outward in a breathing mode. Stripped permeant ions enter widened hydrogen bonds in the core helices of these segments. Driven by concentration differences and the electric field, the ions hop along transient pathways across the channel, appearing as fractal, stochastic bursts of single-channel currents. To support order amid thermal fluctuations, an object must be of a minimum size. The critical role of an ion channel's size suggests that the evolution of Metazoa became possible only after its DNA had grown enough to code for proteins larger than the correlation length.

Néel vector switching and terahertz spin-wave excitation in Mn2Au due to femtosecond spin-transfer torques

Efficient and fast manipulation of antiferromagnets has to date remained a challenging task, hindering their application in spintronic devices. For ultrafast operation of such devices, it is highly desirable to be able to control the antiferromagnetic order within picoseconds - a timescale that is difficult to achieve with electrical circuits. Here, we demonstrate that bursts of spin-polarized hot-electron currents emerging due to laser-induced ultrafast demagnetization are able to efficiently excite spin dynamics in antiferromagnetic Mn$_2$Au by exerting a spin-transfer torque on femtosecond timescales. We combine quantitative superdiffusive transport and atomistic spin-model calculations to describe a spin-valve-type trilayer consisting of Fe$|$Cu$|$Mn$_2$Au. Our results demonstrate that femtosecond spin-transfer torques can switch the Mn$_2$Au layer within a few picoseconds. In addition, we find that spin waves with high frequencies up to several THz can be excited in Mn$_2$Au.

Depolarization-induced bursts of miniature synaptic currents in individual synapses of developing cerebellum.

In central synapses, spontaneous transmitter release observed in the absence of action potential firing is often considered as a random process lacking time or space specificity. However, when studying miniature glutamatergic currents at cerebellar synapses between parallel fibers and molecular layer interneurons, we found that these currents were sometimes organized in bursts of events occurring at high frequency (about 30 Hz). Bursts displayed homogeneous quantal size amplitudes. Furthermore, in the presence of the desensitization inhibitor cyclothiazide, successive events within a burst displayed quantal amplitude occlusion. Based on these findings, we conclude that bursts originate in individual synapses. Bursts were enhanced by increasing either the external potassium concentration or the external calcium concentration, and they were strongly inhibited when blocking voltage-gated calcium channels by cadmium. Bursts were prevalent in elevated potassium concentration during the formation of the molecular layer but were infrequent later in development. Since postsynaptic AMPA receptors are largely calcium permeant in developing parallel fiber-interneuron synapses, we propose that bursts involve presynaptic calcium transients implicating presynaptic voltage-gated calcium channels, together with postsynaptic calcium transients implicating postsynaptic AMPA receptors. These simultaneous pre- and postsynaptic calcium transients may contribute to the formation and/or stabilization of synaptic connections.

Quantum states in disordered media. I. Low-pass filter approach

The current burst in research activities on disordered semiconductors calls for the development of appropriate theoretical tools that reveal the features of electron states in random potentials while avoiding the time-consuming numerical solution of the Schr\"odinger equation. Among various approaches suggested so far, the low-pass filter approach of Halperin and Lax (HL) and the so-called localization landscape technique (LLT) have received most recognition in the community. We prove that the HL approach becomes equivalent to the LLT for the specific case of a Lorentzian filter when applied to the Schr\"odinger equation with a constant mass. Advantageously, the low-pass filter approach allows further optimization beyond the Lorentzian shape. We propose the global HL filter as optimal filter with only a single length scale, namely, the size of the localized wave packets. As an application, we design an optimized potential landscape for a (semi-)classical calculation of the number of strongly localized states that faithfully reproduce the exact solution for a random white-noise potential in one dimension.

State of charge and state of health estimation strategies for lithium-ion batteries

Abstract Due to the widespread use of renewable energy sources, lithium-ion batteries have developed rapidly because renewable energy sources, such as photovoltaics and wind, which are very much affected by the environment and their power output can be better leveled if lithium-ion batteries are used. Battery state of charge (SOC) characterizes the remaining battery power, while battery state of health (SOH) characterizes the battery life state, and they are key parameters to characterize the state of lithium-ion batteries. In terms of battery SOC estimation, this paper optimizes the extended Kalman filtering (EKF) algorithm weights to adjust the weights during high current bursts to obtain better SOC tracking performance and optimizes the back propagation (BP) neural network for SOH estimation to obtain better weights to further obtain more accurate battery SOH. The feasibility of the optimized algorithm is validated by the experimental platform.

Powering Electronic Implants by High Frequency Volume Conduction: In Human Validation.

Wireless power transfer (WPT) is used as an alternative to batteries to accomplish miniaturization in electronic medical implants. However, established WPT methods require bulky parts within the implant or cumbersome external systems, hindering minimally invasive deployments and the development of networks of implants. As an alternative, we propose a WPT approach based on volume conduction of high frequency (HF) current bursts. These currents are applied through external electrodes and are collected by the implants through two electrodes at their opposite ends. This approach avoids bulky components, enabling the development of flexible threadlike implants. We study in humans if HF (6.78 MHz) current bursts complying with safety standards and applied through two textile electrodes strapped around a limb can provide substantial powers from pairs of implanted electrodes. Time averaged electric powers obtained from needle electrodes (diameter = 0.4 mm, length = 3 mm, separation = 30 mm) inserted into arms and lower legs of five healthy participants were 5.9 ± 0.7 mW and 2.4 ± 0.3 mW respectively. We also characterize the coupling between the external system and the implants using personalized two-port impedance models generated from medical images. The results demonstrate that innocuous and imperceptible HF current bursts that flow through the tissues by volume conduction can be used to wirelessly power threadlike implants. This is the first time that WPT based on volume conduction is demonstrated in humans. This method overcomes the limitations of existing WPT methods in terms of minimal invasiveness and usability.

The brain stimulation of DLPFC regulates choice preference in intertemporal choice self-other differences

Intertemporal choice requires to make decision by evaluating the value of two options consisting of different times and benefits. The dorsolateral prefrontal cortex (DLPFC) is a key brain region for modulating intertemporal choice. The aim of this study is to investigate the effect of non-invasive brain stimulation over DLPFC on intertemporal choice behavior for self and others. We used transcranial direct current stimulation (tDCS) and continuous theta burst stimulation (cTBS) to stimulate bilateral DLPFC in two experiments respectively. After stimulation, subjects made a choice between a Smaller-Sooner (SS) reward and a Larger-Later (LL) reward in intertemporal choice task. The results showed that cTBS stimulation on the left DLPFC reduced the choice preference for SS reward when individuals made choices for themselves. The cTBS stimulation caused preference difference between choosing for self and parents. But tDCS stimulation had no effect on regulating choice preference. In addition, subjects preferred SS reward for self than strangers. Time-types and monetary difference of rewards affected the choice preference. The presence of immediate time increased the choice preference of SS reward. As the monetary difference increased, the choice proportion of SS reward decreased. Our study demonstrates that brain stimulation on the left DLPFC can regulate choice preference behavior in intertemporal choice.

Revisit the periodicity of SGR J1935+2154 bursts with updated sample

ABSTRACT Since FRB 200428 has been found to be associated with an X-ray burst from the Galactic magnetar SGR J1935+2154, it is interesting to explore whether the magnetar bursts also follow the similar active periodic behaviour as some repeating FRBs. Previous studies show that there is possible period of about 230 days in SGR J1935+2154 bursts. Here, we collected an updated burst sample from SGR J1935+2154, including all bursts reported by Fermi/GBM and GECAM till 2022 January. We also developed a targeted search pipeline to reveal more bursts from SGR J1935+2154 in the Fermi/GBM data from 2008 August to 2014 December (i.e. before the first burst detected by Swift/BAT). With this burst sample, we re-analysed the possible periodicity of SGR J1935+2154 bursts using the Period Folding and Lomb–Scargle Periodogram methods. Our results show that the periodicity ∼238 days reported in literature is probably fake and the observation effects may introduce false periods (i.e. 55 days) according to simulation tests. We find that, for the current burst sample, the most probable period is 126.88 ± 2.05 days, which could be interpreted as the precession of the magnetar. However, we note that the whole burst history is very complicated and difficult to be perfectly accommodated with any period reported thus far, therefore more monitoring observations of SGR J1935+2154 are required to test any periodicity hypothesis.

Wireless networks of injectable microelectronic stimulators based on rectification of volume conducted high frequency currents

Objective. To develop and in vivo demonstrate threadlike wireless implantable neuromuscular microstimulators that are digitally addressable. Approach. These devices perform, through its two electrodes, electronic rectification of innocuous high frequency current bursts delivered by volume conduction via epidermal textile electrodes. By avoiding the need of large components to obtain electrical energy, this approach allows the development of thin devices that can be intramuscularly implanted by minimally invasive procedures such as injection. For compliance with electrical safety standards, this approach requires a minimum distance, in the order of millimeters or a very few centimeters, between the implant electrodes. Additionally, the devices must cause minimal mechanical damage to tissues, avoid dislocation and be adequate for long-term implantation. Considering these requirements, the implants were conceived as tubular and flexible devices with two electrodes at opposite ends and, at the middle section, a hermetic metallic capsule housing the electronics. Main results. The developed implants have a submillimetric diameter (0.97 mm diameter, 35 mm length) and consist of a microcircuit, which contains a single custom-developed integrated circuit, housed within a titanium capsule (0.7 mm diameter, 6.5 mm length), and two platinum–iridium coils that form two electrodes (3 mm length) located at opposite ends of a silicone body. These neuromuscular stimulators are addressable, allowing to establish a network of microstimulators that can be controlled independently. Their operation was demonstrated in an acute study by injecting a few of them in the hind limb of anesthetized rabbits and inducing controlled and independent contractions. Significance. These results show the feasibility of manufacturing threadlike wireless addressable neuromuscular stimulators by using fabrication techniques and materials well established for chronic electronic implants. Although long-term operation still must be demonstrated, the obtained results pave the way to the clinical development of advanced motor neuroprostheses formed by dense networks of such wireless devices.

Floating EMG sensors and stimulators wirelessly powered and operated by volume conduction for networked neuroprosthetics

BackgroundImplantable neuroprostheses consisting of a central electronic unit wired to electrodes benefit thousands of patients worldwide. However, they present limitations that restrict their use. Those limitations, which are more adverse in motor neuroprostheses, mostly arise from their bulkiness and the need to perform complex surgical implantation procedures. Alternatively, it has been proposed the development of distributed networks of intramuscular wireless microsensors and microstimulators that communicate with external systems for analyzing neuromuscular activity and performing stimulation or controlling external devices. This paradigm requires the development of miniaturized implants that can be wirelessly powered and operated by an external system. To accomplish this, we propose a wireless power transfer (WPT) and communications approach based on volume conduction of innocuous high frequency (HF) current bursts. The currents are applied through external textile electrodes and are collected by the wireless devices through two electrodes for powering and bidirectional digital communications. As these devices do not require bulky components for obtaining power, they may have a flexible threadlike conformation, facilitating deep implantation by injection.MethodsWe report the design and evaluation of advanced prototypes based on the above approach. The system consists of an external unit, floating semi-implantable devices for sensing and stimulation, and a bidirectional communications protocol. The devices are intended for their future use in acute human trials to demonstrate the distributed paradigm. The technology is assayed in vitro using an agar phantom, and in vivo in hindlimbs of anesthetized rabbits.ResultsThe semi-implantable devices were able to power and bidirectionally communicate with the external unit. Using 13 commands modulated in innocuous 3 MHz HF current bursts, the external unit configured the sensing and stimulation parameters, and controlled their execution. Raw EMG was successfully acquired by the wireless devices at 1 ksps.ConclusionsThe demonstrated approach overcomes key limitations of existing neuroprostheses, paving the way to the development of distributed flexible threadlike sensors and stimulators. To the best of our knowledge, these devices are the first based on WPT by volume conduction that can work as EMG sensors and as electrical stimulators in a network of wireless devices.

Gq neuromodulation of BLA parvalbumin interneurons induces burst firing and mediates fear-associated network and behavioral state transition in mice

Patterned coordination of network activity in the basolateral amygdala (BLA) is important for fear expression. Neuromodulatory systems play an essential role in regulating changes between behavioral states, however the mechanisms underlying this neuromodulatory control of transitions between brain and behavioral states remain largely unknown. We show that chemogenetic Gq activation and α1 adrenoreceptor activation in mouse BLA parvalbumin (PV) interneurons induces a previously undescribed, stereotyped phasic bursting in PV neurons and time-locked synchronized bursts of inhibitory postsynaptic currents and phasic firing in BLA principal neurons. This Gq-coupled receptor activation in PV neurons suppresses gamma oscillations in vivo and in an ex vivo slice model, and facilitates fear memory recall, which is consistent with BLA gamma suppression during conditioned fear expression. Thus, here we identify a neuromodulatory mechanism in PV inhibitory interneurons of the BLA which regulates BLA network oscillations and fear memory recall.