Neural correlates of perceptual similarity masking in primate V1.

Visual detection is a fundamental natural task. Detection becomes more challenging as the similarity between the target and the background in which it is embedded increases, a phenomenon termed 'similarity masking'. To test the hypothesis that V1 contributes to similarity masking, we used voltage sensitive dye imaging (VSDI) to measure V1 population responses while macaque monkeys performed a detection task under varying levels of target-background similarity. Paradoxically, we find that during an initial transient phase, V1 responses to the target are enhanced, rather than suppressed, by target-background similarity. This effect reverses in the second phase of the response, so that in this phase V1 signals are positively correlated with the behavioral effect of similarity. Finally, we show that a simple model with delayed divisive normalization can qualitatively account for our findings. Overall, our results support the hypothesis that a nonlinear gain control mechanism in V1 contributes to perceptual similarity masking.

Functional Dissection of Ipsilateral and Contralateral Neural Activity Propagation Using Voltage-Sensitive Dye Imaging in Mouse Prefrontal Cortex.

Prefrontal cortex (PFC) intrahemispheric activity and the interhemispheric connection have a significant impact on neuropsychiatric disorder pathology. This study aimed to generate a functional map of FC intrahemispheric and interhemispheric connections. Functional dissection of mouse PFCs was performed using the voltage-sensitive dye (VSD) imaging method with high speed (1 ms/frame), high resolution (256 × 256 pixels), and a large field of view (∼10 mm). Acute serial 350 µm slices were prepared from the bregma covering the PFC and numbered 1-5 based on their distance from the bregma (i.e., 1.70, 1.34, 0.98, 0.62, and 0.26 mm) with reference to the Mouse Brain Atlas (Paxinos and Franklin, 2008). The neural response to electrical stimulation was measured at nine sites and then averaged, and a functional map of the propagation patterns was created. Intracortical propagation was observed in slices 3-5, encompassing the anterior cingulate cortex (ACC) and corpus callosum (CC). The activity reached area 33 of the ACC. Direct white matter stimulation activated area 33 in both hemispheres. Similar findings were obtained via DiI staining of the CC. Imaging analysis revealed directional biases in neural signals traveling within the ACC, whereby the signal transmission speed and probability varied based on the signal direction. Specifically, the spread of neural signals from cg2 to cg1 was stronger than that from cingulate cortex area 1(cg1) to cingulate cortex area 2(cg2), which has implications for interhemispheric functional connections. These findings highlight the importance of understanding the PFC functional anatomy in evaluating neuromodulators like serotonin and dopamine, as well as other factors related to neuropsychiatric diseases.

Functional development of olfactory nerve-related neural circuits in the embryonic chick forebrain revealed by voltage-sensitive dye imaging.

Multiple-site optical recordings with NK2761, a voltage-sensitive absorption dye, were applied to the embryonic chick olfactory system, and the functional development of olfactory nerve (N.I)-related neural circuits was examined in the forebrain. The stimulation of the N. I elicited neural responses in N.I-olfactory bulb (OB)-forebrain preparations at the embryonic 8-12 day (E8-E12) stages. At the E11 stage, we functionally identified two circuits projecting from the OB to the forebrain. The first circuit passed through the ventral side of the forebrain and spread in the dorso-caudal direction, whereas the second circuit passed through the dorsal side to the first circuit. Pharmacological experiments showed that N-methyl-D -aspartate (NMDA) receptor function was more significant for the transfer of sensory information in these circuits. The functional development of N.I-related circuits was investigated, and the results obtained revealed that the ventral circuit was generated earlier than the dorsal circuit. Neural responses in the ventral circuit were detected from the E9 stage in normal physiological solution and the E8 stage in Mg2+ -free solution, which activated NMDA receptor function. At the E10 stage, neural responses in the dorsal circuit were clearly recognised in addition to ventral responses. We attempted to identify possible candidates for relay nuclei in the forebrain by comparing contour line maps of the optical signal amplitude with previously reported neuroanatomical data. The results suggest that N.I-related neural circuits from the periphery to the subpallium functionally mature earlier than those to the pallium during ontogenesis.

Voltage imaging in the olfactory bulb using transgenic mouse lines expressing the genetically encoded voltage indicator ArcLight.

Genetically encoded voltage indicators (GEVIs) allow optical recordings of membrane potential changes in defined cell populations. Transgenic reporter animals that facilitate precise and repeatable targeting with high expression levels would further the use of GEVIs in the in vivo mammalian brain. However, the literature on developing and applying transgenic mouse lines as vehicles for GEVI expression is limited. Here we report the first in vivo experiments using a transgenic reporter mouse for the GEVI ArcLight, which utilizes a Cre/tTA dependent expression system (TIGRE 1.0). We developed two mouse lines with ArcLight expression restricted to either olfactory receptor neurons, or a subpopulation of interneurons located in the granule and glomerular layers in the olfactory bulb. The ArcLight expression in these lines was sufficient for in vivo imaging of odorant responses in single trials using epifluorescence and 2-photon imaging. The voltage responses were odor-specific and concentration-dependent, which supported earlier studies about perceptual transformations carried out by the bulb that used calcium sensors of neural activity. This study demonstrates that the ArcLight transgenic line is a flexible genetic tool that can be used to record the neuronal electrical activity of different cell types with a signal-to-noise ratio that is comparable to previous reports using viral transduction.

Spatiotemporal structure of sensory-evoked and spontaneous activity revealed by mesoscale imaging in anesthetized and awake mice.

Stimuli-evoked and spontaneous brain activity propagates across the cortex in diverse spatiotemporal patterns. Despite extensive studies, the relationship between spontaneous and evoked activity is poorly understood. We investigate this relationship by comparing the amplitude, speed, direction, and complexity of propagation trajectories of spontaneous and evoked activity elicited with visual, auditory, and tactile stimuli using mesoscale wide-field imaging in mice. For both spontaneous and evoked activity, the speed and direction of propagation is modulated by the amplitude. However, spontaneous activity has a higher complexity of the propagation trajectories. For low stimulus strengths, evoked activity amplitude and speed is similar to that of spontaneous activity but becomes dissimilar at higher stimulus strengths. These findings are consistent with observations that primary sensory areas receive widespread inputs from other cortical regions, and during rest, the cortex tends to reactivate traces of complex multisensory experiences that might have occurred in exhibition of different behaviors.

Stop the beat to see the rhythm: excitation-contraction uncoupling in cardiac research.

Optical mapping is an imaging technique that is extensively used in cardiovascular research, wherein parameter-sensitive fluorescent indicators are used to study the electrophysiology and excitation-contraction coupling of cardiac tissues. Despite many benefits of optical mapping, eliminating motion artifacts within the optical signals is a major challenge, as myocardial contraction interferes with the faithful acquisition of action potentials and intracellular calcium transients. As such, excitation-contraction uncoupling agents are frequently used to reduce signal distortion by suppressing contraction. When compared with other uncoupling agents, blebbistatin is the most frequently used, as it offers increased potency with minimal direct effects on cardiac electrophysiology. Nevertheless, blebbistatin may exert secondary effects on electrical activity, metabolism, and coronary flow, and the incorrect administration of blebbistatin to cardiac tissue can prove detrimental, resulting in erroneous interpretation of optical mapping results. In this "Getting It Right" perspective, we briefly review the literature regarding the use of blebbistatin in cardiac optical mapping experiments, highlight potential secondary effects of blebbistatin on cardiac electrical activity and metabolic demand, and conclude with the consensus of the authors on best practices for effectively using blebbistatin in optical mapping studies of cardiac tissue.

Neurovascular dynamics of repeated cortical spreading depolarizations after acute brain injury.

Cortical spreading depolarizations (CSDs) are increasingly suspected to play an exacerbating role in a range of acute brain injuries, including stroke, possibly through their interactions with cortical blood flow. We use simultaneous wide-field imaging of neural activity and hemodynamics in Thy1-GCaMP6f mice to explore the neurovascular dynamics of CSDs during and following Rose Bengal-mediated photothrombosis. CSDs are observed in all mice as slow-moving waves of GCaMP fluorescence extending far beyond the photothrombotic area. Initial CSDs are accompanied by profound vasoconstriction and leave residual oligemia and ischemia in their wake. Later, CSDs evoke variable responses, from constriction to biphasic to vasodilation. However, CSD-evoked vasoconstriction is found to be more likely during rapid, high-amplitude CSDs in regions with stronger oligemia and ischemia, which, in turn, worsens after each repeated CSD. This feedback loop may explain the variable but potentially devastating effects of CSDs in the context of acute brain injury.

Enabling comprehensive optogenetic studies of mouse hearts by simultaneous opto-electrical panoramic mapping and stimulation.

During the last decade, cardiac optogenetics has turned into an essential tool for investigating cardiac function in general and for assessing functional interactions between different myocardial cell types in particular. To advance exploitation of the unique research opportunities offered by this method, we develop a panoramic opto-electrical measurement and stimulation (POEMS) system for mouse hearts. The core of the experimental platform is composed of 294 optical fibers and 64 electrodes that form a cup which embraces the entire ventricular surface of mouse hearts and enables straightforward 'drop&go' experimentation. The flexible assignment of fibers and electrodes to recording or stimulation tasks permits a precise tailoring of experiments to the specific requirements of individual optogenetic constructs thereby avoiding spectral congestion. Validation experiments with hearts from transgenic animals expressing the optogenetic voltage reporters ASAP1 and ArcLight-Q239 demonstrate concordance of simultaneously recorded panoramic optical and electrical activation maps. The feasibility of single fiber optical stimulation is proven with hearts expressing the optogenetic voltage actuator ReaChR. Adaptation of the POEMS system to larger hearts and incorporation of additional sensors can be achieved by redesigning the system-core accordingly.

Ventricular arrhythmias in mouse models of diabetic kidney disease.

Chronic kidney disease (CKD) affects more than 20 million people in the US, and it is associated with a significantly increased risk of sudden cardiac death (SCD). Despite the significance, the mechanistic relationship between SCD and CKD is not clear and there are few effective therapies. Using optical mapping techniques, we tested the hypothesis that mouse models of progressive diabetic kidney disease (DKD) exhibit enhanced ventricular arrhythmia incidence and underlying arrhythmia substrates. Compared to wild-type mice, both Leprdb/db eNOS-/- (2KO) and high fat diet plus low dose streptozotocin (HFD + STZ) mouse models of DKD experienced sudden death and greater arrhythmia inducibility, which was more common with isoproterenol than programmed electrical stimulation. 2KO mice demonstrated slowed conduction velocity, prolonged action potential duration (APD), and myocardial fibrosis; both 2KO and HFD + STZ mice exhibited arrhythmias and calcium dysregulation with isoproterenol challenge. Finally, circulating concentrations of the uremic toxin asymmetric dimethylarginine (ADMA) were elevated in 2KO mice. Incubation of human cardiac myocytes with ADMA prolonged APD, as also observed in 2KO mice hearts ex vivo. The present study elucidates an arrhythmia-associated mechanism of sudden death associated with DKD, which may lead to more effective treatments in the vulnerable DKD patient population.

Bringing together the best of chemistry and biology: hybrid indicators for imaging neuronal membrane potential.

Membrane potential is an indispensable biophysical signal in neurobiology. Imaging neuronal electrical signals with fluorescent indicators allows for non-invasive recording at high spatial resolution. Over the past decades, both genetically encoded voltage indicators (GEVIs) and organic voltage sensing dyes (OVSDs) have been developed to achieve imaging membrane potential dynamics in cultured neurons and in vivo. More recently, hybrid voltage indicators have gained increasing attention due to their superior fluorescent quantum yield and photostability as compared to conventional GEVIs. In this mini-review, we summarize the design, characterization and biological applications of hybrid voltage indicators, and discuss future improvements.

A novel system for mapping regional electrical properties and characterizing arrhythmia in isolated intact rat atria.

Detailed global maps of atrial electrical activity are needed to understand mechanisms of atrial rhythm disturbance in small animal models of heart disease. To date, optical mapping systems have not provided enough spatial resolution across sufficiently extensive regions of intact atrial preparations to achieve this goal. The aim of this study was to develop an integrated platform for quantifying regional electrical properties and analyzing reentrant arrhythmia in a biatrial preparation. Intact atria from 6/7-mo-old female spontaneously hypertensive rats (SHRs; n = 6) were isolated and secured in a constant flow superfusion chamber at 37°C. Optical mapping was performed with the membrane-voltage dye di-4-ANEPPS using LED excitation and a scientific complementary metal-oxide semiconductor (sCMOS) camera. Programmed stimulus trains were applied from right atrial (RA) and left atrial (LA) sites to assess rate-dependent electrical behavior and to induce atrial arrhythmia. Signal-to-noise ratio was improved by sequential processing steps that included spatial smoothing, temporal filtering, and, in stable rhythms, ensemble-averaging. Activation time, repolarization time, and action potential duration (APD) maps were constructed at high spatial resolution for a wide range of coupling intervals. These data were highly consistent within and between experiments. They confirmed preferential atrial conduction pathways and demonstrated distinct medial-to-lateral APD gradients. We also showed that reentrant arrhythmias induced in this preparation were explained by the spatial variation of these electrical properties. Our new methodology provides a robust means of 1) quantifying regional electrical properties in the intact rat atria at higher spatiotemporal resolution than previously reported, and 2) characterizing reentrant arrhythmia and analyzing mechanisms that give rise to it.NEW & NOTEWORTHY Despite wide-ranging optical mapping studies, detailed information on regional atrial electrical properties in small animal models of heart disease and how these contribute to reentrant arrhythmia remains limited. We have developed a novel experimental platform that enables both to be achieved in a geometrically intact isolated rat bi-atrial preparation.

Prenatal ethanol exposure impairs the conduction delay at the atrioventricular junction in the looping heart.

The etiology of ethanol-related congenital heart defects has been the focus of much study, but most research has concentrated on cellular and molecular mechanisms. We have shown with optical coherence tomography (OCT) that ethanol exposure led to increased retrograde flow and smaller atrioventricular (AV) cushions compared with controls. Since AV cushions play a role in patterning the conduction delay at the atrioventricular junction (AVJ), this study aims to investigate whether ethanol exposure alters the AVJ conduction in early looping hearts and whether this alteration is related to the decreased cushion size. Quail embryos were exposed to a single dose of ethanol at gastrulation, and Hamburger-Hamilton stage 19-20 hearts were dissected for imaging. Cardiac conduction was measured using an optical mapping microscope and we imaged the endocardial cushions using OCT. Our results showed that, compared with controls, ethanol-exposed embryos exhibited abnormally fast AVJ conduction and reduced cushion size. However, this increased conduction velocity (CV) did not strictly correlate with decreased cushion volume and thickness. By matching the CV map to the cushion-size map along the inflow heart tube, we found that the slowest conduction location was consistently at the atrial side of the AVJ, which had the thinner cushions, not at the thickest cushion location at the ventricular side as expected. Our findings reveal regional differences in the AVJ myocardium even at this early stage in heart development. These findings reveal the early steps leading to the heterogeneity and complexity of conduction at the mature AVJ, a site where arrhythmias can be initiated.NEW & NOTEWORTHY To the best of our knowledge, this is the first study investigating the impact of ethanol exposure on the early cardiac conduction system. Our results showed that ethanol-exposed embryos exhibited abnormally fast atrioventricular conduction. In addition, our findings, in CV measurements and endocardial cushion thickness, reveal regional differences in the AVJ myocardium even at this early stage in heart development, suggesting that the differentiation and maturation at this site are complex and warrant further studies.

In silico voltage-sensitive dye imaging reveals the emergent dynamics of cortical populations.

Voltage-sensitive dye imaging (VSDI) is a powerful technique for interrogating membrane potential dynamics in assemblies of cortical neurons, but with effective resolution limits that confound interpretation. To address this limitation, we developed an in silico model of VSDI in a biologically faithful digital reconstruction of rodent neocortical microcircuitry. Using this model, we extend previous experimental observations regarding the cellular origins of VSDI, finding that the signal is driven primarily by neurons in layers 2/3 and 5, and that VSDI measurements do not capture individual spikes. Furthermore, we test the capacity of VSD image sequences to discriminate between afferent thalamic inputs at various spatial locations to estimate a lower bound on the functional resolution of VSDI. Our approach underscores the power of a bottom-up computational approach for relating scales of cortical processing.

Similar masking effects of natural backgrounds on detection performances in humans, macaques, and macaque-V1 population responses.

Visual systems evolve to process the stimuli that arise in the organism's natural environment, and hence, to fully understand the neural computations in the visual system, it is important to measure behavioral and neural responses to natural visual stimuli. Here, we measured psychometric and neurometric functions in the macaque monkey for detection of a windowed sine-wave target in uniform backgrounds and in natural backgrounds of various contrasts. The neurometric functions were obtained by near-optimal decoding of voltage-sensitive-dye-imaging (VSDI) responses at the retinotopic scale in primary visual cortex (V1). The results were compared with previous human psychophysical measurements made under the same conditions. We found that human and macaque behavioral thresholds followed the generalized Weber's law as function of contrast, and that both the slopes and the intercepts of the threshold as a function of background contrast match each other up to a single scale factor. We also found that the neurometric thresholds followed the generalized Weber's law with slopes and intercepts matching the behavioral slopes and intercepts up to a single scale factor. We conclude that human and macaque ability to detect targets in natural backgrounds are affected in the same way by background contrast, that these effects are consistent with population decoding at the retinotopic scale by down-stream circuits, and that the macaque monkey is an appropriate animal model for gaining an understanding of the neural mechanisms in humans for detecting targets in natural backgrounds. Finally, we discuss limitations of the current study and potential next steps.NEW & NOTEWORTHY We measured macaque detection performance in natural images and compared their performance to the detection sensitivity of neurophysiological responses recorded in the primary visual cortex (V1), and to the performance of human subjects. We found that 1) human and macaque behavioral performances are in quantitative agreement and 2) are consistent with near-optimal decoding of V1 population responses.

Population imaging discrepancies between a genetically-encoded calcium indicator (GECI) versus a genetically-encoded voltage indicator (GEVI).

Genetically-encoded calcium indicators (GECIs) are essential for studying brain function, while voltage indicators (GEVIs) are slowly permeating neuroscience. Fundamentally, GECI and GEVI measure different things, but both are advertised as reporters of "neuronal activity". We quantified the similarities and differences between calcium and voltage imaging modalities, in the context of population activity (without single-cell resolution) in brain slices. GECI optical signals showed 8-20 times better SNR than GEVI signals, but GECI signals attenuated more with distance from the stimulation site. We show the exact temporal discrepancy between calcium and voltage imaging modalities, and discuss the misleading aspects of GECI imaging. For example, population voltage signals already repolarized to the baseline (~ disappeared), while the GECI signals were still near maximum. The region-to-region propagation latencies, easily captured by GEVI imaging, are blurred in GECI imaging. Temporal summation of GECI signals is highly exaggerated, causing uniform voltage events produced by neuronal populations to appear with highly variable amplitudes in GECI population traces. Relative signal amplitudes in GECI recordings are thus misleading. In simultaneous recordings from multiple sites, the compound EPSP signals in cortical neuropil (population signals) are less distorted by GEVIs than by GECIs.

In Vitro Cell Selectivity of Reversible and Irreversible: Electroporation in Cardiac Tissue.

[Figure: see text].

Mirroring Action Potentials: Label-Free, Accurate, and Noninvasive Electrophysiological Recordings of Human-Derived Cardiomyocytes.

The electrophysiological recording of action potentials in human cells is a long-sought objective due to its pivotal importance in many disciplines. Among the developed techniques, invasiveness remains a common issue, causing cytotoxicity or altering unpredictably cell physiological response. In this work, a new approach for recording intracellular signals of outstanding quality and with noninvasiveness is introduced. By taking profit of the concept of mirror charge in classical electrodynamics, the new proposed device transduces cell ionic currents into mirror charges in a microfluidic chamber, thus realizing a virtual mirror cell. By monitoring mirror charge dynamics, it is possible to effectively record the action potentials fired by the cells. Since there is no need for accessing or interacting with the cells, the method is intrinsically noninvasive. In addition, being based on optical recording, it shows high spatial resolution and high parallelization. As shown through a set of experiments, the presented methodology is an ideal candidate for the next generation devices for the reliable assessment of cardiotoxicity on human-derived cardiomyocytes. More generally, it paves the way toward a new family of in vitro biodevices that will lay a new milestone in the field of electrophysiology.

Ventricular fibrillation mechanism and global fibrillatory organization are determined by gap junction coupling and fibrosis pattern.

AIMS: Conflicting data exist supporting differing mechanisms for sustaining ventricular fibrillation (VF), ranging from disorganized multiple-wavelet activation to organized rotational activities (RAs). Abnormal gap junction (GJ) coupling and fibrosis are important in initiation and maintenance of VF. We investigated whether differing ventricular fibrosis patterns and the degree of GJ coupling affected the underlying VF mechanism. METHODS AND RESULTS: Optical mapping of 65 Langendorff-perfused rat hearts was performed to study VF mechanisms in control hearts with acute GJ modulation, and separately in three differing chronic ventricular fibrosis models; compact fibrosis (CF), diffuse fibrosis (DiF), and patchy fibrosis (PF). VF dynamics were quantified with phase mapping and frequency dominance index (FDI) analysis, a power ratio of the highest amplitude dominant frequency in the cardiac frequency spectrum. Enhanced GJ coupling with rotigaptide (n = 10) progressively organized fibrillation in a concentration-dependent manner; increasing FDI (0 nM: 0.53 ± 0.04, 80 nM: 0.78 ± 0.03, P < 0.001), increasing RA-sustained VF time (0 nM: 44 ± 6%, 80 nM: 94 ± 2%, P < 0.001), and stabilized RAs (maximum rotations for an RA; 0 nM: 5.4 ± 0.5, 80 nM: 48.2 ± 12.3, P < 0.001). GJ uncoupling with carbenoxolone progressively disorganized VF; the FDI decreased (0 µM: 0.60 ± 0.05, 50 µM: 0.17 ± 0.03, P < 0.001) and RA-sustained VF time decreased (0 µM: 61 ± 9%, 50 µM: 3 ± 2%, P < 0.001). In CF, VF activity was disorganized and the RA-sustained VF time was the lowest (CF: 27 ± 7% vs. PF: 75 ± 5%, P < 0.001). Global fibrillatory organization measured by FDI was highest in PF (PF: 0.67 ± 0.05 vs. CF: 0.33 ± 0.03, P < 0.001). PF harboured the longest duration and most spatially stable RAs (patchy: 1411 ± 266 ms vs. compact: 354 ± 38 ms, P < 0.001). DiF (n = 11) exhibited an intermediately organized VF pattern, sustained by a combination of multiple-wavelets and short-lived RAs. CONCLUSION: The degree of GJ coupling and pattern of fibrosis influences the mechanism sustaining VF. There is a continuous spectrum of organization in VF, ranging between globally organized fibrillation sustained by stable RAs and disorganized, possibly multiple-wavelet driven fibrillation with no RAs.

Idebenone Protects against Atherosclerosis in Apolipoprotein E-Deficient Mice Via Activation of the SIRT3-SOD2-mtROS Pathway.

PURPOSE: Atherosclerosis, a chronic disease of the arteries, results from pathological processes including the accumulation and aggregation of oxidized low-density lipoprotein (oxLDL) in the vessel walls, development of neointima, formation of a fibrous cap, and migration of immune cells to damaged vascular endothelium. Recent studies have shown that mitochondrial dysfunction is closely associated with the development and progression of atherosclerosis. Idebenone, a short-chain benzoquinone similar in structure to coenzyme Q10, can effectively clear oxygen free radicals as an electron carrier and antioxidant. In the present study, we aim to investigate weather idebenone protects against atherosclerosis in apolipoprotein E-deficient (apoE-/-) mice. METHODS: apoE-/- mice receiving a high-fat diet (HFD) were treated with idebenone for 16 weeks. A total of 60 mice were randomized into the following four groups: (1) HFD, (2) HFD and low-dose idebenone (100 mg/kg/d), (3) HFD and medium-dose idebenone (200 mg/kg/d), and (4) HFD and high-dose (400 mg/kg/d). Proteomic analysis was performed between the HFD and idebenone-high-dose group. Plaque analysis was carried out by histological and immunohistochemical staining. Western blot, TUNEL staining, and MitoSOX assays were performed in human umbilical vein endothelial cells (HUVECs) to investigate the SIRT3-SOD2-mtROS pathway. RESULTS: Histological and morphological analysis demonstrated that idebenone significantly reduced plaque burden and plaque size. Idebenone treatment effectively stabilized the atherosclerotic plaques. In mice treated with idebenone, 351 up-regulated and 379 down-regulated proteins were found to be significantly altered in proteomic analysis. In particular, the expression of SIRT3, SOD2, and NLRP3 was significantly regulated in the idebenone treatment groups compared with the HFD group both in vivo and in vitro. We further confirmed that idebenone protected against endothelial cell damage and inhibited the production of mitochondrial reactive oxygen species (mtROS) in cholesterol-treated HUVECs. CONCLUSIONS: We demonstrated that idebenone acted as a mitochondrial protective agent by inhibiting the activation of NLPR3 via the SIRT3-SOD2-mtROS pathway. Idebenone may be a promising therapy for patients with atherosclerosis by improving mitochondrial dysfunction and inhibiting oxidative stress.

Cardiac optogenetics: a decade of enlightenment.

The electromechanical function of the heart involves complex, coordinated activity over time and space. Life-threatening cardiac arrhythmias arise from asynchrony in these space-time events; therefore, therapies for prevention and treatment require fundamental understanding and the ability to visualize, perturb and control cardiac activity. Optogenetics combines optical and molecular biology (genetic) approaches for light-enabled sensing and actuation of electrical activity with unprecedented spatiotemporal resolution and parallelism. The year 2020 marks a decade of developments in cardiac optogenetics since this technology was adopted from neuroscience and applied to the heart. In this Review, we appraise a decade of advances that define near-term (immediate) translation based on all-optical electrophysiology, including high-throughput screening, cardiotoxicity testing and personalized medicine assays, and long-term (aspirational) prospects for clinical translation of cardiac optogenetics, including new optical therapies for rhythm control. The main translational opportunities and challenges for optogenetics to be fully embraced in cardiology are also discussed.