Modified mRNA Vaccines Protect against Zika Virus Infection.

The emergence of ZIKV infection has prompted a global effort to develop safe and effective vaccines. We engineered a lipid nanoparticle (LNP) encapsulated modified mRNA vaccine encoding wild-type or variant ZIKV structural genes and tested immunogenicity and protection in mice. Two doses of modified mRNA LNPs encoding prM-E genes that produced virus-like particles resulted in high neutralizing antibody titers (∼1/100,000) that protected against ZIKV infection and conferred sterilizing immunity. To offset a theoretical concern of ZIKV vaccines inducing antibodies that cross-react with the related dengue virus (DENV), we designed modified prM-E RNA encoding mutations destroying the conserved fusion-loop epitope in the E protein. This variant protected against ZIKV and diminished production of antibodies enhancing DENV infection in cells or mice. A modified mRNA vaccine can prevent ZIKV disease and be adapted to reduce the risk of sensitizing individuals to subsequent exposure to DENV, should this become a clinically relevant concern.

MicroRNA-155 Plays Selective Cell-Intrinsic Roles in Brain-Infiltrating Immune Cell Populations during Neuroinflammation.

The proinflammatory microRNA-155 (miR-155) is highly expressed in the serum and CNS lesions of patients with multiple sclerosis (MS). Global knockout (KO) of miR-155 in mice confers resistance to a mouse model of MS, experimental autoimmune encephalomyelitis (EAE), by reducing the encephalogenic potential of CNS-infiltrating Th17 T cells. However, cell-intrinsic roles for miR-155 during EAE have not been formally determined. In this study, we use single-cell RNA sequencing and cell-specific conditional miR-155 KOs to determine the importance of miR-155 expression in distinct immune cell populations. Time-course single-cell sequencing revealed reductions in T cells, macrophages, and dendritic cells (DCs) in global miR-155 KO mice compared with wild-type controls at day 21 after EAE induction. Deletion of miR-155 in T cells, driven by CD4 Cre, significantly reduced disease severity similar to global miR-155 KOs. CD11c Cre-mediated deletion of miR-155 in DCs also resulted in a modest yet significant reduction in the development of EAE, with both T cell- and DC-specific KOs showing a reduction in Th17 T cell infiltration into the CNS. Although miR-155 is highly expressed in infiltrating macrophages during EAE, deletion of miR-155 using LysM Cre did not impact disease severity. Taken together, these data show that although miR-155 is highly expressed in most infiltrating immune cells, miR-155 has distinct roles and requirements depending on the cell type, and we have demonstrated this using the gold standard conditional KO approach. This provides insights into which functionally relevant cell types should be targeted by the next generation of miRNA therapeutics.

Predicting disruptive instabilities in controlled fusion plasmas through deep learning.

Nuclear fusion power delivered by magnetic-confinement tokamak reactors holds the promise of sustainable and clean energy1. The avoidance of large-scale plasma instabilities called disruptions within these reactors2,3 is one of the most pressing challenges4,5, because disruptions can halt power production and damage key components. Disruptions are particularly harmful for large burning-plasma systems such as the multibillion-dollar International Thermonuclear Experimental Reactor (ITER) project6 currently under construction, which aims to be the first reactor that produces more power from fusion than is injected to heat the plasma. Here we present a method based on deep learning for forecasting disruptions. Our method extends considerably the capabilities of previous strategies such as first-principles-based5 and classical machine-learning7-11 approaches. In particular, it delivers reliable predictions for machines other than the one on which it was trained-a crucial requirement for future large reactors that cannot afford training disruptions. Our approach takes advantage of high-dimensional training data to boost predictive performance while also engaging supercomputing resources at the largest scale to improve accuracy and speed. Trained on experimental data from the largest tokamaks in the United States (DIII-D12) and the world (Joint European Torus, JET13), our method can also be applied to specific tasks such as prediction with long warning times: this opens up the possibility of moving from passive disruption prediction to active reactor control and optimization. These initial results illustrate the potential for deep learning to accelerate progress in fusion-energy science and, more generally, in the understanding and prediction of complex physical systems.

Greater prefrontal activation during sitting toe tapping predicts severer freezing of gait in Parkinson's disease: an fNIRS study.

OBJECTIVE: Previous studies have revealed that, compared with Parkinson's disease (PD) patients without freezing of gait (FoG), the ones with FoG showed greater prefrontal activation while doing lower-limb movements involving standing, walking and turning, which require both locomotor and balance control. However, the relation between FoG and pure locomotor control as well as its underlying mechanism remain unclear. METHODS: A total of 56 PD subjects were recruited and allocated to PD-FoG and PD-noFoG subgroups, and 34 age-matched heathy adults were included as heathy control (HC). Functional near-infrared spectroscopy was used to measure their prefrontal activation in a sitting lower-limb movement task, wherein subjects were asked to sit and tap their right toes as big and as fast as possible. RESULTS: Result of one-way ANOVA (Group: PD-FoG vs. PD-noFoG vs. HC) revealed greater activation in the right prefrontal cortex in the PD-FoG group than in the other 2 groups. Linear mixed-effects model showed consistent result. Furthermore, the right prefrontal activation positively correlated with the severity of FoG symptoms in PD-FoG patients. CONCLUSION: These findings suggested that PD patients with FoG require additional cognitive resources to compensate their damaged automaticity in locomotor control, which is more pronounced in severe FoG patients than milder ones.

Standard Balloon Angioplasty Versus Serranator Serration Balloon Angioplasty for the Treatment of Below-the-Knee Artery Occlusive Disease: A Single-Center Subanalysis From the PRELUDE-BTK Prospective Study.

BACKGROUND: Endovascular interventions in infrapopliteal occlusive artery disease are becoming more complex, and this frequently tests the standard method of treatment, plain old balloon angioplasty (POBA). The potential that serration angioplasty could produce a more acceptable tibial artery lumen was assessed in this study. AIM: The aim of this single-center subgroup analysis was to compare acute angiographic results after endovascular treatment using the Serranator serration balloon catheter in patients participating in the PRELUDE-BTK trial with POBA of the infrapopliteal arteries. A secondary objective was to assess post-treatment hemodynamic improvements. METHODS: Our center enrolled 15 subjects and treated 17 lesions within the multicenter prospective core laboratory-adjudicated PRELUDE-BTK study. A 25 lesions analyzed separately were treated with POBA and then compared with the Serranator subset. In both cohorts, lesions were treated with either plain angioplasty or Serranator as a stand-alone therapy; subsequent methods, such as drug elution technologies, were not used. Acute angiographic results were analyzed by the SynvaCor angiographic core laboratory. To assess volumetric flow rates, data were analyzed with a fluid flow simulation software and compared against Poiseuille's Law. RESULTS: Final residual stenosis was 17.2%±8.2% in the Serranator group versus 33.7%±15.7% in the POBA group. The mean lumen diameter (MLD) gain for the Serranator group and the POBA group was 1.64±0.41 mm and 1.33±0.63 mm, respectively. The average atmospheric balloon inflation pressure was 5 ATM in the Serranator group versus 9 ATM in the POBA group. Neither group required a bailout stent; however, it was notable that there were significantly more chronic total occlusions (CTOs) treated in the Serranator group at 41.2% versus 12% in the POBA group. Regarding the effectiveness in improving hemodynamic blood flow for non-CTO lesions, the calculated average ratio of post-treatment to pre-treatment flow rates in the Serranator group was 238% than that for the POBA group. For CTO cases where pre-treatment flow rate was zero, final residual stenosis was used as the parameter for comparison. The Serranator group showed a 62% improvement in final residual stenosis over POBA. CONCLUSION: Endovascular treatment of the infrapopliteal arteries by use of the Serranator serration balloon provides a novel and promising method of action compared with standard balloon angioplasty and, thus, may have a leading role in complex below-the-knee arterial lesions. CLINICAL IMPACT: The Serranator device might help to adequately address issues with conventional routine techniques for the treatment of complex lesions in infrapopliteal arteries in patients with advanced stages of PAD and critical limb ischemia. Integrating modern technologies such as the Serranator balloon catheter into clinical routine is mandatory in order to gain a more favorable outcome in these severely diseased patients and, particularly, to reduce mortality and morbidity.

Internet of Things: Development Intelligent Programmable IoT Controller for Emerging Industry Applications.

The Internet of Things (IoT) has become critical to the implementation of Industry 4.0. The successful operation of smart manufacturing depends on the ability to connect everything together. In this research, we applied the TOC (Theory of Constraints) to develop a wireless Wi-Fi intelligent programmable IoT controller that can be connected to and easily control PLCs. By applying the TOC-focused thinking steps to break through their original limitations, the development process guides the user to use the powerful and simple flow language process control syntax to efficiently connect to PLCs and realize the full range of IoT applications. Finally, this research uses oil-water mixer equipment as the target of continuous improvement and verification. The verification results meet the requirements of the default function. The IoT controller developed in this research uses a marine boiler to illustrate the application. The successful development of flow control language by TOC in this research will enable academic research on PLC-derivative applications. The results of this research will help more SMEs to move into smart manufacturing and the new realm of Industry 4.0.

CD4+ T cells promote humoral immunity and viral control during Zika virus infection.

Several Zika virus (ZIKV) vaccines designed to elicit protective antibody (Ab) responses are currently under rapid development, but the underlying mechanisms that control the magnitude and quality of the Ab response remain unclear. Here, we investigated the CD4+ T cell response to primary intravenous and intravaginal infection with ZIKV. Using the LysMCre+Ifnar1fl/fl (myeloid type I IFN receptor-deficient) C57BL/6 mouse models, we identified six I-Ab-restricted ZIKV epitopes that stimulated CD4+ T cells with a predominantly cytotoxic Th1 phenotype in mice primed with ZIKV. Intravenous and intravaginal infection with ZIKV effectively induced follicular helper and regulatory CD4+ T cells. Treatment of mice with a CD4+ T cell-depleting Ab reduced the plasma cell, germinal center B cell, and IgG responses to ZIKV without affecting the CD8+ T cell response. CD4+ T cells were required to protect mice from a lethal dose of ZIKV after infection intravaginally, but not intravenously. However, adoptive transfer and peptide immunization experiments showed a role for memory CD4+ T cells in ZIKV clearance in mice challenged intravenously. These results demonstrate that CD4+ T cells are required mainly for the generation of a ZIKV-specific humoral response but not for an efficient CD8+ T cell response. Thus, CD4+ T cells could be important mediators of protection against ZIKV, depending on the infection or vaccination context.

Correction: CD4+ T cells promote humoral immunity and viral control during Zika virus infection.

[This corrects the article DOI: 10.1371/journal.ppat.1007474.].

Cross-Presentation of Soluble and Cell-Associated Antigen by Murine Hepatocytes Is Enhanced by Collectrin Expression.

Cross-presentation is a modular series of intracellular events dictating the internalization and subsequent MHC class I (MHC I) display of extracellular Ags. This process has been defined in dendritic cells and plays a fundamental role in the induction of CD8+ T cell immunity during viral, intracellular bacterial, and antitumor responses. Herein, acute viral infection of murine liver with adenovirus, a model for intrahepatic cross-presentation, confirms hepatocytes directly contribute to cross-presentation of Ags and priming the pool of naive CD8+ T cells within the liver microenvironment. Processing of soluble and cell-associated Ags into peptide displayed by MHC I is however defective in hepatocytes lacking collectrin, an intracellular chaperone protein that localizes within the endoplasmic reticulum-Golgi intermediate compartment. Loss of hepatic collectrin expression leads to the diminished cross-priming and expansion of cytolytic antiviral CD8+ T cells. This study demonstrates that collectrin positively regulates processing of engulfed Ags into MHC I:peptide complexes within hepatocytes. Collectrin-mediated cross-presentation supports intrahepatic adaptive antiviral immune responses and may lead to insights into the nature of how the liver acts as a primary site of CD8+ T cell activation.

Antitumor immunity is defective in T cell-specific microRNA-155-deficient mice and is rescued by immune checkpoint blockade.

MicroRNA-155 (miR-155) regulates antitumor immune responses. However, its specific functions within distinct immune cell types have not been delineated in conditional KO mouse models. In this study, we investigated the role of miR-155 specifically within T cells during the immune response to syngeneic tumors. We found that miR-155 expression within T cells is required to limit syngeneic tumor growth and promote IFNγ production by T cells within the tumor microenvironment. Consequently, we found that miR-155 expression by T cells is necessary for proper tumor-associated macrophage expression of IFNγ-inducible genes. We also found that immune checkpoint-blocking (ICB) antibodies against programmed cell death protein 1/programmed death ligand 1 (PD-1/PD-L1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) restored antitumor immunity in miR-155 T cell-conditional KO mice. We noted that these ICB antibodies rescued the levels of IFNγ-expressing T cells, expression of multiple activation and effector genes expressed by tumor-infiltrating CD8+ and CD4+ T cells, and tumor-associated macrophage activation. Moreover, the ICB approach partially restored expression of several derepressed miR-155 targets in tumor-infiltrating, miR-155-deficient CD8+ T cells, suggesting that miR-155 and ICB regulate overlapping pathways to promote antitumor immunity. Taken together, our findings highlight the multifaceted role of miR-155 in T cells, in which it promotes antitumor immunity. These results suggest that the augmentation of miR-155 expression could be used to improve anticancer immunotherapies.

CD8+ T Cells Can Mediate Short-Term Protection against Heterotypic Dengue Virus Reinfection in Mice.

UNLABELLED: Dengue virus (DENV) is a major public health threat worldwide. Infection with one of the four serotypes of DENV results in a transient period of protection against reinfection with all serotypes (cross-protection), followed by lifelong immunity to the infecting serotype. While a protective role for neutralizing antibody responses is well established, the contribution of T cells to reinfection is less clear, especially during heterotypic reinfection. This study investigates the role of T cells during homotypic and heterotypic DENV reinfection. Mice were sequentially infected with homotypic or heterotypic DENV serotypes, and T cell subsets were depleted before the second infection to assess the role of DENV-primed T cells during reinfection. Mice primed nonlethally with DENV were protected against reinfection with either a homotypic or heterotypic serotype 2 weeks later. Homotypic priming induced a robust neutralizing antibody response, whereas heterotypic priming elicited binding, but nonneutralizing antibodies. CD8(+) T cells were required for protection against heterotypic, but not homotypic, reinfection. These results suggest that T cells can contribute crucially to protection against heterotypic reinfection in situations where humoral responses alone may not be protective. Our findings have important implications for vaccine design, as they suggest that inducing both humoral and cellular responses during vaccination may maximize protective efficacy across all DENV serotypes. IMPORTANCE: Dengue virus is present in more than 120 countries in tropical and subtropical regions. Infection with dengue virus can be asymptomatic, but it can also progress into the potentially lethal severe dengue disease. There are four closely related dengue virus serotypes. Infection with one serotype results in a transient period of resistance against all serotypes (cross-protection), followed by lifelong resistance to the infecting serotype, but not the other ones. The duration and mechanisms of the transient cross-protection period remain elusive. This study investigates the contribution of cellular immunity to cross-protection using mouse models of DENV infection. Our results demonstrate that cellular immunity is crucial to mediate cross-protection against reinfection with a different serotype, but not for protection against reinfection with the same serotype. A better understanding of the mediators responsible for the cross-protection period is important for vaccine design, as an ideal vaccine against dengue virus should efficiently protect against all serotypes.

CD8+ T cells prevent antigen-induced antibody-dependent enhancement of dengue disease in mice.

Dengue virus (DENV) causes pathologies ranging from the febrile illness dengue fever to the potentially lethal severe dengue disease. A major risk factor for developing severe dengue disease is the presence of subprotective DENV-reactive Abs from a previous infection (or from an immune mother), which can induce Ab-dependent enhancement of infection (ADE). However, infection in the presence of subprotective anti-DENV Abs does not always result in severe disease, suggesting that other factors influence disease severity. In this study we investigated how CD8(+) T cell responses influence the outcome of Ab-mediated severe dengue disease. Mice were primed with aluminum hydroxide-adjuvanted UV-inactivated DENV prior to challenge with DENV. Priming failed to induce robust CD8(+) T cell responses, and it induced nonneutralizing Ab responses that increased disease severity upon infection. Transfer of exogenous DENV-activated CD8(+) T cells into primed mice prior to infection prevented Ab-dependent enhancement and dramatically reduced viral load. Our results suggest that in the presence of subprotective anti-DENV Abs, efficient CD8(+) T cell responses reduce the risk of Ab-mediated severe dengue disease.

The Listeria monocytogenes hibernation-promoting factor is required for the formation of 100S ribosomes, optimal fitness, and pathogenesis.

During exposure to certain stresses, bacteria dimerize pairs of 70S ribosomes into translationally silent 100S particles in a process called ribosome hibernation. Although the biological roles of ribosome hibernation are not completely understood, this process appears to represent a conserved and adaptive response that contributes to optimal survival during stress and post-exponential-phase growth. Hibernating ribosomes are formed by the activity of one or more highly conserved proteins; gammaproteobacteria produce two relevant proteins, ribosome modulation factor (RMF) and hibernation promoting factor (HPF), while most Gram-positive bacteria produce a single, longer HPF protein. Here, we report the formation of 100S ribosomes by an HPF homolog in Listeria monocytogenes. L. monocytogenes 100S ribosomes were observed by sucrose density gradient centrifugation of bacterial extracts during mid-logarithmic phase, peaked at the transition to stationary phase, and persisted at lower levels during post-exponential-phase growth. 100S ribosomes were undetectable in bacteria carrying an hpf::Himar1 transposon insertion, indicating that HPF is required for ribosome hibernation in L. monocytogenes. Additionally, epitope-tagged HPF cosedimented with 100S ribosomes, supporting its previously described direct role in 100S formation. We examined hpf mRNA by quantitative PCR (qPCR) and identified several conditions that upregulated its expression, including carbon starvation, heat shock, and exposure to high concentrations of salt or ethanol. Survival of HPF-deficient bacteria was impaired under certain conditions both in vitro and during animal infection, providing evidence for the biological relevance of 100S ribosome formation.

Clinicopathological effects of pepper (oleoresin capsicum) spray.

OBJECTIVES: Pepper (oleoresin capsicum) spray is one of the most common riot-control measures used today. Although not lethal, exposure of pepper spray can cause injury to different organ systems. This review aimed to summarise the major clinicopathological effects of pepper spray in humans. DATA SOURCES: MEDLINE, EMBASE database, and Cochrane Database of Systematic Reviews were used to search for terms associated with the clinicopathological effects of pepper spray in humans and those describing the pathophysiology of capsaicin. A phone interview with two individuals recently exposed to pepper spray was also conducted to establish clinical symptoms. STUDY SELECTION: Major key words used for the MEDLINE search were "pepper spray", "OC spray", "oleoresin capsicum"; and other key words as "riot control agents", "capsaicin", and "capsaicinoid". We then combined the key words "capsaicin" and "capsaicinoid" with the major key words to narrow down the number of articles. A search with other databases including EMBASE and Cochrane Database of Systematic Reviews was also conducted with the above phrases to identify any additional related articles. DATA EXTRACTION: All article searches were confined to human study. The bibliography of articles was screened for additional relevant studies including non-indexed reports, and information from these was also recorded. Non-English articles were included in the search. DATA SYNTHESIS: Fifteen articles were considered relevant. Oleoresin capsicum causes almost instantaneous irritative symptoms to the skin, eyes, and respiratory system. Dermatological effects include a burning sensation, erythema, and hyperalgesia. Ophthalmic effects involve blepharospasm, conjunctivitis, peri-orbital oedema, and corneal pathology. Following inhalation, a stinging or burning sensation can be felt in the nose with sore throat, chest tightness, or dyspnoea. The major pathophysiology is neurogenic inflammation caused by capsaicinoid in the pepper spray. There is no antidote for oleoresin capsicum. Treatment consists of thorough decontamination, symptom-directed supportive measures, and early detection and treatment of systemic toxicity. Decontamination should be carefully carried out to avoid contamination of the surrounding skin and clothing. CONCLUSION: Pepper (oleoresin capsicum) spray is an effective riot-control agent and does not cause life-threatening clinical effects in the majority of exposed individuals. Early decontamination minimises the irritant effects.

Revision of the New World cycad weevils of the subtribe Allocorynina, with description of two new genera and three new subgenera (Coleoptera: Belidae: Oxycoryninae).

The taxonomy of the weevils inhabiting male cycad cones in the New World is reviewed. All species belong in a single subtribe, Allocorynina, of the family Belidae, subfamily Oxycoryninae and tribe Oxycorynini and are known to develop only in cones of the cycad genera Dioon and Zamia. Most species of Rhopalotria Chevrolat develop in male cones of Zamia ranging from Mexico, Belize, the Caribbean (Cuba, Isle of Youth, Cayman Islands, Jamaica and the Bahamas) to southern Florida, and one species in those of Dioon spinulosum in Mexico. Rhopalotria consists of three previously described species, two previously described genus-group names (treated herein as subgenera) and four new species described herein: subgenus Allocorynus Sharp with R. calonjei n. sp., R. furfuracea n. sp., R. mollis (Sharp) and R. vovidesi n. sp., and the nominate subgenus Rhopalotria with R. dimidiata Chevrolat, R. meerowi n. sp. and R. slossoni (Schaeffer). The species of Parallocorynus Voss develop only in cones of Dioon in Mexico, and the genus consists of one previously described species, the nominate subgenus and three new subgenera and 11 new species described herein: subgenus Dysicorynus n. subg. with P. andrewsi n. sp. and P. sonorensis n. sp., subgenus Eocorynus n. subg. with P. chemnicki n. sp. and P. schiblii n. sp., subgenus Neocorynus n. subg. with P. iglesiasi n. sp. and P. inexpectatus n. sp., and the nominate subgenus Parallocorynus with P. bicolor (Voss), P. gregoryi n. sp., P. jonesi n. sp., P. norstogi n. sp., P. perezfarrerai n. sp. and P. salasae n. sp. Two new genera are described, Protocorynus with one new species in Honduras, P. bontai, and Notorhopalotria with four new species ranging from Costa Rica to Colombia, N. montgomeryensis, N. panamensis, N. platysoma and N. taylori. Keys to genera, subgenera and species are provided. All of these weevils are believed to be involved in pollination of their host cycads.

Spindle oscillations in communicating axons within a reconstituted hippocampal formation are strongest in CA3 without thalamus.

Spindle-shaped waves of oscillations emerge in EEG scalp recordings during human and rodent non-REM sleep. The association of these 10-16 Hz oscillations with events during prior wakefulness suggests a role in memory consolidation. Human and rodent depth electrodes in the brain record strong spindles throughout the cortex and hippocampus, with possible origins in the thalamus. However, the source and targets of the spindle oscillations from the hippocampus are unclear. Here, we employed an in vitro reconstruction of four subregions of the hippocampal formation with separate microfluidic tunnels for single axon communication between subregions assembled on top of a microelectrode array. We recorded spontaneous 400-1000 ms long spindle waves at 10-16 Hz in single axons passing between subregions as well as from individual neurons in those subregions. Spindles were nested within slow waves. The highest amplitudes and most frequent occurrence suggest origins in CA3 neurons that send feed-forward axons into CA1 and feedback axons into DG. Spindles had 50-70% slower conduction velocities than spikes and were not phase-locked to spikes suggesting that spindle mechanisms are independent of action potentials. Therefore, consolidation of declarative-cognitive memories in the hippocampus may be separate from the more easily accessible consolidation of memories related to thalamic motor function.

The flow of axonal information among hippocampal sub-regions 2: patterned stimulation sharpens routing of information transmission.

The sub-regions of the hippocampal formation are essential for episodic learning and memory formation, yet the spike dynamics of each region contributing to this function are poorly understood, in part because of a lack of access to the inter-regional communicating axons. Here, we reconstructed hippocampal networks confined to four subcompartments in 2D cultures on a multi-electrode array that monitors individual communicating axons. In our novel device, somal, and axonal activity was measured simultaneously with the ability to ascertain the direction and speed of information transmission. Each sub-region and inter-regional axons had unique power-law spiking dynamics, indicating differences in computational functions, with abundant axonal feedback. After stimulation, spiking, and burst rates decreased in all sub-regions, spikes per burst generally decreased, intraburst spike rates increased, and burst duration decreased, which were specific for each sub-region. These changes in spiking dynamics post-stimulation were found to occupy a narrow range, consistent with the maintenance of the network at a critical state. Functional connections between the sub-region neurons and communicating axons in our device revealed homeostatic network routing strategies post-stimulation in which spontaneous feedback activity was selectively decreased and balanced by decreased feed-forward activity. Post-stimulation, the number of functional connections per array decreased, but the reliability of those connections increased. The networks maintained a balance in spiking and bursting dynamics in response to stimulation and sharpened network routing. These plastic characteristics of the network revealed the dynamic architecture of hippocampal computations in response to stimulation by selective routing on a spatiotemporal scale in single axons.

Hippocampal network axons respond to patterned theta burst stimulation with lower activity of initially higher spike train similarity from EC to DG and later similarity of axons from CA1 to EC.

Objective. Decoding memory functions for each hippocampal subregion involves extensive understanding of how each hippocampal subnetwork processes input stimuli. Theta burst stimulation (TBS) recapitulates natural brain stimuli which potentiates synapses in hippocampal circuits. TBS is typically applied to a bundle of axons to measure the immediate response in a downstream subregion like the cornu ammonis 1 (CA1). Yet little is known about network processing in response to stimulation, especially because individual axonal transmission between subregions is not accessible.Approach. To address these limitations, we reverse engineered the hippocampal network on a micro-electrode array partitioned by a MEMS four-chambered device with interconnecting microfluidic tunnels. The micro tunnels allowed monitoring single axon transmission which is inaccessible in slices orin vivo. The four chambers were plated separately with entorhinal cortex (EC), dentate gyrus (DG), CA1, and CA3 neurons. The patterned TBS was delivered to the EC hippocampal gateway. Evoked spike pattern similarity in each subregions was quantified with Jaccard distance metrics of spike timing.Main results. We found that the network subregion produced unique axonal responses to different stimulation patterns. Single site and multisite stimulations caused distinct information routing of axonal spikes in the network. The most spatially similar output at axons from CA3 to CA1 reflected the auto association within CA3 recurrent networks. Moreover, the spike pattern similarities shifted from high levels for axons to and from DG at 0.2 s repeat stimuli to greater similarity in axons to and from CA1 for repetitions at 10 s intervals. This time-dependent response suggested that CA3 encoded temporal information and axons transmitted the information to CA1.Significance. Our design and interrogation approach provide first insights into differences in information transmission between the four subregions of the structured hippocampal network and the dynamic pattern variations in response to stimulation at the subregional level to achieve probabilistic pattern separation and novelty detection.