Population imaging of neural activity in awake behaving mice.

A longstanding goal in neuroscience has been to image membrane voltage across a population of individual neurons in an awake, behaving mammal. Here we describe a genetically encoded fluorescent voltage indicator, SomArchon, which exhibits millisecond response times and is compatible with optogenetic control, and which increases the sensitivity, signal-to-noise ratio, and number of neurons observable several-fold over previously published fully genetically encoded reagents1-8. Under conventional one-photon microscopy, SomArchon enables the routine population analysis of around 13 neurons at once, in multiple brain regions (cortex, hippocampus, and striatum) of head-fixed, awake, behaving mice. Using SomArchon, we detected both positive and negative responses of striatal neurons during movement, as previously reported by electrophysiology but not easily detected using modern calcium imaging techniques9-11, highlighting the power of voltage imaging to reveal bidirectional modulation. We also examined how spikes relate to the subthreshold theta oscillations of individual hippocampal neurons, with SomArchon showing that the spikes of individual neurons are more phase-locked to their own subthreshold theta oscillations than to local field potential theta oscillations. Thus, SomArchon reports both spikes and subthreshold voltage dynamics in awake, behaving mice.

Publisher Correction: A robotic multidimensional directed evolution approach applied to fluorescent voltage reporters.

In the version of this article originally published, the bottom of Figure 4f,g was partially truncated in the PDF. The error has been corrected in the PDF version of this article.

A robotic multidimensional directed evolution approach applied to fluorescent voltage reporters.

We developed a new way to engineer complex proteins toward multidimensional specifications using a simple, yet scalable, directed evolution strategy. By robotically picking mammalian cells that were identified, under a microscope, as expressing proteins that simultaneously exhibit several specific properties, we can screen hundreds of thousands of proteins in a library in just a few hours, evaluating each along multiple performance axes. To demonstrate the power of this approach, we created a genetically encoded fluorescent voltage indicator, simultaneously optimizing its brightness and membrane localization using our microscopy-guided cell-picking strategy. We produced the high-performance opsin-based fluorescent voltage reporter Archon1 and demonstrated its utility by imaging spiking and millivolt-scale subthreshold and synaptic activity in acute mouse brain slices and in larval zebrafish in vivo. We also measured postsynaptic responses downstream of optogenetically controlled neurons in C. elegans.

An E3-ligase-based method for ablating inhibitory synapses.

Although neuronal activity can be modulated using a variety of techniques, there are currently few methods for controlling neuronal connectivity. We introduce a tool (GFE3) that mediates the fast, specific and reversible elimination of inhibitory synaptic inputs onto genetically determined neurons. GFE3 is a fusion between an E3 ligase, which mediates the ubiquitination and rapid degradation of proteins, and a recombinant, antibody-like protein (FingR) that binds to gephyrin. Expression of GFE3 leads to a strong and specific reduction of gephyrin in culture or in vivo and to a substantial decrease in phasic inhibition onto cells that express GFE3. By temporarily expressing GFE3 we showed that inhibitory synapses regrow following ablation. Thus, we have created a simple, reversible method for modulating inhibitory synaptic input onto genetically determined cells.

All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins.

All-optical electrophysiology-spatially resolved simultaneous optical perturbation and measurement of membrane voltage-would open new vistas in neuroscience research. We evolved two archaerhodopsin-based voltage indicators, QuasAr1 and QuasAr2, which show improved brightness and voltage sensitivity, have microsecond response times and produce no photocurrent. We engineered a channelrhodopsin actuator, CheRiff, which shows high light sensitivity and rapid kinetics and is spectrally orthogonal to the QuasArs. A coexpression vector, Optopatch, enabled cross-talk-free genetically targeted all-optical electrophysiology. In cultured rat neurons, we combined Optopatch with patterned optical excitation to probe back-propagating action potentials (APs) in dendritic spines, synaptic transmission, subcellular microsecond-timescale details of AP propagation, and simultaneous firing of many neurons in a network. Optopatch measurements revealed homeostatic tuning of intrinsic excitability in human stem cell-derived neurons. In rat brain slices, Optopatch induced and reported APs and subthreshold events with high signal-to-noise ratios. The Optopatch platform enables high-throughput, spatially resolved electrophysiology without the use of conventional electrodes.

Multiphasic modulation of cholinergic interneurons by nigrostriatal afferents.

The motor and learning functions of the striatum are critically dependent on synaptic transmission from midbrain dopamine neurons and striatal cholinergic interneurons (CINs). Both neural populations alter their discharge in vivo in response to salient sensory stimuli, albeit in opposite directions. Whereas midbrain dopamine neurons respond to salient stimuli with a brief burst of activity, CINs exhibit a distinct pause in firing that is often followed by a period of increased excitability. Although this "pause-rebound" sensory response requires dopaminergic signaling, the precise mechanisms underlying the modulation of CIN firing by dopaminergic afferents remain unclear. Here, we show that phasic activation of nigrostriatal afferents in a mouse striatal slice preparation is sufficient to evoke a pause-rebound response in CINs. Using a combination of optogenetic, electrophysiological, and pharmacological approaches, we demonstrate that synaptically released dopamine inhibits CINs through type 2 dopamine receptors, while another unidentified transmitter mediates the delayed excitation. These findings imply that, in addition to their direct effects on striatal projection neurons, midbrain dopamine neurons indirectly modulate striatal output by dynamically controlling cholinergic tone. In addition, our data suggest that phasic dopaminergic activity may directly participate in the characteristic pause-rebound sensory response that CINs exhibit in vivo in response to salient and conditioned stimuli.

Neto2 modulation of kainate receptors with different subunit compositions.

Kainate receptors are less well understood than other glutamate receptors, and synaptic kainate receptors display properties that differ from recombinant receptors. In particular, the slow decay of kainate receptor synaptic currents contrasts with the rapid deactivation and desensitization of receptors expressed in heterologous cells. We recently identified Neuropilin and Tolloid like-2 (Neto2) as a novel accessory subunit of kainate receptors and showed that Neto2 modulates the gating kinetics of GluK2 receptors. However, the kainate receptor family consists of five different subunits (GluK1-5) that can form homomeric and heteromeric receptors with different functional properties. Here, we tested whether Neto2 modulation varies with subunit composition. Rapid application techniques were used to apply glutamate to outside-out patches that contained GluK1, GluK1/5, or GluK2/5 kainate receptors. Coexpression of Neto2 slowed desensitization to varying degrees. Responses to 1 ms pulses of glutamate were also slowed by Neto2, especially for receptors containing GluK5, as were postsynaptic currents in neurons expressing recombinant kainate receptors. In addition, Neto2 markedly increased the rate at which some receptors recovered from desensitization. These results suggest that Neto2 modulates the function of most kainate receptors.

[Loss of information in cross-sectoral treatment: causes and solutions]. / Informationsverluste bei sektorübergreifender Behandlung: Ursachen und Lösungen.

Missing information on patients and their medication is a leading cause of medication errors and preventable harm. The TOP Projects uses pharmacy claim data and electronic decision support to improve quality and safety of care on hospital admission. In a survey 100 % of responding hospitals in Germany consider this approach helpful and important to improve availability of necessary information and medication safety and to reduce workload.

A brain-specific SGK1 splice isoform regulates expression of ASIC1 in neurons.

Neurodegenerative diseases and noxious stimuli to the brain enhance transcription of serum- and glucocorticoid-induced kinase-1 (SGK1). Here, we report that the SGK1 gene encodes a brain-specific additional isoform, SGK1.1, which exhibits distinct regulation, properties, and functional effects. SGK1.1 decreases expression of the acid-sensing ion channel-1 (ASIC1); thereby, SGK1.1 may limit neuronal injury associated to activation of ASIC1 in ischemia. Given that neurons express at least two splice isoforms, SGK1 and SGK1.1, driven by distinct promoters, any changes in SGK1 transcript level must be examined to define the isoform induced by each stimulus or neurological disorder.

Large-scale voltage imaging in behaving mice using targeted illumination.

Recent improvements in genetically encoded voltage indicators enabled optical imaging of action potentials and subthreshold transmembrane voltage in vivo. To perform high-speed voltage imaging of many neurons simultaneously over a large anatomical area, widefield microscopy remains an essential tool. However, the lack of optical sectioning makes widefield microscopy prone to background cross-contamination. We implemented a digital-micromirror-device-based targeted illumination strategy to restrict illumination to the cells of interest and quantified the resulting improvement both theoretically and experimentally with SomArchon expressing neurons. We found that targeted illumination increased SomArchon signal contrast, decreased photobleaching, and reduced background cross-contamination. With the use of a high-speed, large-area sCMOS camera, we routinely imaged tens of spiking neurons simultaneously over minutes in behaving mice. Thus, the targeted illumination strategy described here offers a simple solution for widefield voltage imaging of many neurons over a large field of view in behaving animals.

Injecting Gryllus bimaculatus Eggs.

Altering gene function in a developing organism is central to different kinds of experiments. While tremendously powerful genetic tools have been developed in traditional model systems, it is difficult to manipulate genes or messenger RNA (mRNA) in most other organisms. At the same time, evolutionary and comparative approaches rely on an exploration of gene function in many different species, necessitating the development and adaptation of techniques for manipulating expression outside currently genetically tractable species. This protocol describes a method for injecting reagents into cricket eggs to assay the effects of a given manipulation on embryonic or larval development. Instructions for how to collect and inject eggs with beveled needles are described. This relatively straightforward technique is flexible and potentially adaptable to other insects. One can gather and inject dozens of eggs in a single experiment, and survival rates for buffer-only injections improve with practice and can be as high as 80%. This technique will support several types of experimental approaches including injection of pharmacological agents, in vitro capped mRNA to express genes of interest, double-stranded RNA (dsRNA) to achieve RNA interference, use of clustered regularly interspaced short palindromic repeats (CRISPR) in concert with CRISPR-associated protein 9 (Cas9) reagents for genomic modification, and transposable elements to generate transient or stable transgenic lines.

Distinct Cortical-Thalamic-Striatal Circuits through the Parafascicular Nucleus.

The thalamic parafascicular nucleus (PF), an excitatory input to the basal ganglia, is targeted with deep-brain stimulation to alleviate a range of neuropsychiatric symptoms. Furthermore, PF lesions disrupt the execution of correct motor actions in uncertain environments. Nevertheless, the circuitry of the PF and its contribution to action selection are poorly understood. We find that, in mice, PF has the highest density of striatum-projecting neurons among all sub-cortical structures. This projection arises from transcriptionally and physiologically distinct classes of PF neurons that are also reciprocally connected with functionally distinct cortical regions, differentially innervate striatal neurons, and are not synaptically connected in PF. Thus, mouse PF contains heterogeneous neurons that are organized into parallel and independent associative, limbic, and somatosensory circuits. Furthermore, these subcircuits share motifs of cortical-PF-cortical and cortical-PF-striatum organization that allow each PF subregion, via its precise connectivity with cortex, to coordinate diverse inputs to striatum.

[Medical centers--from a Statutory Health Insurance Company's perspective]. / Medizinische Zentren--Anforderungen aus Sicht der GKV.

In the course of recent activities involving the bundling of healthcare institutions into so-called "Centers", many kinds of Healthcare Centers, Breast Centers, Comprehensive Cancer Centers etc. have been established. The term "Center" suggests expertise and superiority, and, without doubt, centers take medical care closer to higher quality and cost efficiency at the same time. However, there are preconditions which need to be fulfilled, such as the compliance with certain structural and process-oriented criteria in patient care. From the perspective of the compulsory health insurance funds, this raises questions regarding the type of centers that should be supported, the requirements that must be met, and the role that centers are assigned within the complex of our healthcare system. For health insurance purposes, Medical Centers provide innovative structural conditions for group-balanced concepts. Since the Statutory Health Insurance System Modernization Act (GKV-Modernisierungsgesetz and 140 a ff. SGB V) has provided individual contract options and inpatient oriented institutions have opened up to offer highly specialized ambulatory treatment (and 116b SGB V), centers have become attractive contractual partners for health insurance companies. The present article describes expectations and requirements in relation to the formation of Medical Centers from the perspective of a compulsory health insurance company, focusing on oncological centers.

[Disease management programs between aspiration and reality. Actually, everything was meant to become much better]. / DMP zwischen Anspruch und Wirklichkeit-- Eigentlich sollte alles besser werden.

By initiating disease management programmes (DMP) the German legislator aimed to optimize the provision of healthcare to chronically ill patients through increasing the competition between sickness funds and healthcare providers and to stimulate quality competition in the healthcare system by simultaneously connecting DMPs to compensatory (wraparound) payments within the risk-adjustment scheme. The intended quality measures have hardly been reflected in the DMP contracts. The present paper presents a preliminary analysis of the population registered for the "Type 2 Diabetes mellitius" DMP: As the sickness funds aim to recruit as many participants as possible, they did not only enrol the high-risk population but relatively young and healthy diabetics as well. Whether DMPs will actually lead to quality improvement and increasing cost-effectiveness cannot be assessed, since the evaluation criteria for DMPs no longer require that sound scientific cost-effectiveness analyses be performed.

Principles of Synaptic Organization of GABAergic Interneurons in the Striatum.

The striatum, the entry nucleus of the basal ganglia, lacks laminar or columnar organization of its principal cells; nevertheless, functional data suggest that it is spatially organized. Here we examine whether the connectivity and synaptic organization of striatal GABAergic interneurons contributes to such spatial organization. Focusing on the two main classes of striatal GABAergic interneurons (fast-spiking interneurons [FSIs] and low-threshold-spiking interneurons [LTSIs]), we apply a combination of optogenetics and viral tracing approaches to dissect striatal microcircuits in mice. Our results reveal fundamental differences between the synaptic organizations of both interneuron types. FSIs target exclusively striatal projection neurons (SPNs) within close proximity and form strong synapses on the proximal somatodendritic region. In contrast, LTSIs target both SPNs and cholinergic interneurons, and synaptic connections onto SPNs are made exclusively over long distances and onto distal dendrites. These results suggest fundamentally different functions of FSIs and LTSIs in shaping striatal output.

Distinct Subunit Domains Govern Synaptic Stability and Specificity of the Kainate Receptor.

Synaptic communication between neurons requires the precise localization of neurotransmitter receptors to the correct synapse type. Kainate-type glutamate receptors restrict synaptic localization that is determined by the afferent presynaptic connection. The mechanisms that govern this input-specific synaptic localization remain unclear. Here, we examine how subunit composition and specific subunit domains contribute to synaptic localization of kainate receptors. The cytoplasmic domain of the GluK2 low-affinity subunit stabilizes kainate receptors at synapses. In contrast, the extracellular domain of the GluK4/5 high-affinity subunit synergistically controls the synaptic specificity of kainate receptors through interaction with C1q-like proteins. Thus, the input-specific synaptic localization of the native kainate receptor complex involves two mechanisms that underlie specificity and stabilization of the receptor at synapses.

Modelling cost effectiveness and cost utility of sequential DMARD therapy including leflunomide in rheumatoid arthritis in Germany: I. Selected DMARDs and patient-related costs.

OBJECTIVE: To quantify direct costs of medication and cost of illness (according to functional capacity) for patients with rheumatoid arthritis (RA) in Germany, allowing further use in a health economic evaluation of sequential therapy with disease-modifying antirheumatic drugs (DMARDs) in specialised, i.e. rheumatological, care in Germany. DESIGN AND SETTING: The analysis was conducted from the societal perspective in Germany using a modelling approach, which was based on secondary analysis of existing data and on data from a sample of 583 patients from the German rheumatological database of 1998. Functional capacity was defined by the Hannover Functional Ability Questionnaire (HFAQ) scores. Costs were calculated from resources utilised and patients' work capacity. Direct costs consisted of outpatient medical services, inpatient treatment, long-term care and rehabilitation treatment. Indirect costs incurred by sick leave and premature retirement were quantified according to the human-capital approach. MAIN OUTCOME MEASURES AND RESULTS: Average total direct costs (year 1998-2001 values) per patient per year for continuous treatment with the selected DMARDs comprising costs for drugs, monitoring and treatment of adverse drug reactions (ADRs) were highest for intramuscular gold (sodium aurothiomalate) [euro 2106 (euro 1 approximately equal to $US 0.91; average of the period from 2000 through 2001)] followed by leflunomide (euro 2010), azathioprine (euro 1878), sulfasalazine (euro 1190), oral methotrexate (euro 708), and lowest for the antimalarials chloroquine/hydroxychloroquine (euro 684). There were additional yearly costs for RA-related non-DMARD medication of euro 554 per patient, including management of ADRs. Mean cost of illness (year 1998 values) excluding medication cost amounted to euro 17,868 per RA patient per year. Annual costs increased with increasing disability, i.e. decreasing functional capacity, of RA patients from euro 6029 per patient with more than 94% of functional capacity to euro 28,509 per patient with <20% of functional capacity. In general, there was a predominance of indirect costs in each of the categories of functional capacity, ranging between 74% and 87% of total (direct and indirect) annual costs per RA patient. Annual direct costs increased from euro 811 to euro 7438 per patient with increasing disability. Inpatient treatment was the predominant component of direct costs. Patients in the worst category (<20%) of function experienced hospital costs that were 6.5 times higher than those of patients in the best category (>94%). CONCLUSIONS: On the basis of the data presented it can be concluded that the results of this investigation are typical for patients in rheumatological care in Germany and can therefore be used in a health economic analysis of different DMARD sequences aimed at changing disease progression over time.

Modelling cost effectiveness and cost utility of sequential DMARD therapy including leflunomide for rheumatoid arthritis in Germany: II. The contribution of leflunomide to efficiency.

OBJECTIVE: To estimate the 3-year incremental cost effectiveness and cost utility of introducing leflunomide into sequential therapy, consisting of the most frequently used disease-modifying antirheumatic drugs (DMARDs), for patients with rheumatoid arthritis in specialised, i.e. rheumatological, care in Germany. DESIGN AND SETTING: The analysis was conducted from the societal perspective in Germany using an existing 3-year simulation model, which was adapted to the German healthcare system after secondary analysis of relevant publications and data. DMARD sequences including leflunomide were compared with those excluding leflunomide. Costs comprised direct costs incurred by treatment and indirect costs incurred by loss of productivity (sick leave and premature retirement) of rheumatoid arthritis patients. Effectiveness parameters were given by response years gained (RYGs) according to the American College of Rheumatology (ACR) criteria for 20%, 50% and 70% improvement (ACR20/50/70RYGs) and by QALYs gained (QALYGs). Costs, effects and QALYs were discounted by 5% per annum. In the base-case analysis, average values of costs, response years and QALYs were applied. Costs were in 1998-2001 values (euro 1 approximately equal to $US 0.91, average of the period from the year 2000 through 2001). MAIN OUTCOME MEASURES AND RESULTS: After 3 years, adding leflunomide was less costly and more effective than the strategy excluding leflunomide when total (direct and indirect) costs were considered. There were savings of euro 271,777 and 8.1, 4.3, 5.1 and 4.9 ACR20RYGs, ACR50RYGs, ACR70RYGs and QALYGs per 100 patients, respectively, obtained through adding leflunomide. Focusing on direct costs, adding leflunomide was more costly and more effective compared with excluding leflunomide, with an incremental cost effectiveness of euro 5004 per ACR20RYG, euro 9535 per ACR50RYG, euro 7996 per ACR70RYG, and an incremental cost utility of euro8301 per QALYG, after 3 years. The robustness of the results was shown in comprehensive sensitivity analyses. In the analysis of extremes, different combinations of the limits of cost, effectiveness and utility parameters were investigated. Adding leflunomide to sequential DMARD therapy remained dominant in 79% of the possible cases, i.e. was less costly and more effective than the strategy excluding leflunomide. Focusing on direct costs, adding leflunomide became dominant in 29% and remained more costly and more effective in 50% of possible cases. CONCLUSIONS: Our analysis suggests, with its underlying data and assumptions, that having leflunomide as an additional option in a DMARD treatment sequence extends the time patients benefit from DMARD therapy at reasonable additional direct costs. Adding leflunomide may even be cost saving when total (direct and indirect) costs are considered. As data on DMARD effectiveness were extracted from the results of clinical trials, real-world data from observational studies would be needed to corroborate the findings of the present analysis.

Metabolism. Lysosomal amino acid transporter SLC38A9 signals arginine sufficiency to mTORC1.

The mechanistic target of rapamycin complex 1 (mTORC1) protein kinase is a master growth regulator that responds to multiple environmental cues. Amino acids stimulate, in a Rag-, Ragulator-, and vacuolar adenosine triphosphatase-dependent fashion, the translocation of mTORC1 to the lysosomal surface, where it interacts with its activator Rheb. Here, we identify SLC38A9, an uncharacterized protein with sequence similarity to amino acid transporters, as a lysosomal transmembrane protein that interacts with the Rag guanosine triphosphatases (GTPases) and Ragulator in an amino acid-sensitive fashion. SLC38A9 transports arginine with a high Michaelis constant, and loss of SLC38A9 represses mTORC1 activation by amino acids, particularly arginine. Overexpression of SLC38A9 or just its Ragulator-binding domain makes mTORC1 signaling insensitive to amino acid starvation but not to Rag activity. Thus, SLC38A9 functions upstream of the Rag GTPases and is an excellent candidate for being an arginine sensor for the mTORC1 pathway.