Unveiling the Role of Side Chain for Improving Nonvolatile Characteristics of Conjugated Polymers-Based Artificial Synapse

Interest has grown in services that consume a significant amount of energy, such as large language models (LLMs), and research is being conducted worldwide on synaptic devices for neuromorphic hardware. However, various complex processes are problematic for the implementation of synaptic properties. Here, synaptic characteristics are implemented through a novel method, namely side chain control of conjugated polymers. The developed devices exhibit the characteristics of the biological brain, especially spike-timing-dependent plasticity (STDP), high-pass filtering, and long-term potentiation/depression (LTP/D). Moreover, the fabricated synaptic devices show enhanced nonvolatile characteristics, such as long retention time (≈102 s), high ratio of Gmax/Gmin, high linearity, and reliable cyclic endurance (≈103 pulses). This study presents a new pathway for next-generation neuromorphic computing by modulating conjugated polymers with side chain control, thereby achieving high-performance synaptic properties.

Proton-selective coating enables fast-kinetics high-mass-loading cathodes for sustainable zinc batteries

The pressing demand for sustainable energy storage solutions has spurred the burgeoning development of aqueous zinc batteries. However, kinetics-sluggish Zn2+ as the dominant charge carriers in cathodes leads to suboptimal charge-storage capacity and durability of aqueous zinc batteries. Here, we discover that an ultrathin two-dimensional polyimine membrane, featured by dual ion-transport nanochannels and rich proton-conduction groups, facilitates rapid and selective proton passing. Subsequently, a distinctive electrochemistry transition shifting from sluggish Zn2+-dominated to fast-kinetics H+-dominated Faradic reactions is achieved for high-mass-loading cathodes by using the polyimine membrane as an interfacial coating. Notably, the NaV3O8·1.5H2O cathode (10 mg cm-2) with this interfacial coating exhibits an ultrahigh areal capacity of 4.5 mAh cm-2 and a state-of-the-art energy density of 33.8 Wh m-2, along with apparently enhanced cycling stability. Additionally, we showcase the applicability of the interfacial proton-selective coating to different cathodes and aqueous electrolytes, validating its universality for developing reliable aqueous batteries.

Magnetic droplet soliton pairs

We demonstrate magnetic droplet soliton pairs in all-perpendicular spin-torque nano-oscillators (STNOs), where one droplet resides in the STNO free layer (FL) and the other in the reference layer (RL). Typically, theoretical, numerical, and experimental droplet studies have focused on the FL, with any additional dynamics in the RL entirely ignored. Here we show that there is not only significant magnetodynamics in the RL, but the RL itself can host a droplet driven by, and coexisting with, the FL droplet. Both single droplets and pairs are observed experimentally as stepwise changes and sharp peaks in the dc and differential resistance, respectively. While the single FL droplet is highly stable, the coexistence state exhibits high-power broadband microwave noise. Furthermore, micromagnetic simulations reveal that the pair dynamics display periodic, quasi-periodic, and chaotic signatures controlled by applied field and current. The strongly interacting and closely spaced droplet pair offers a unique platform for fundamental studies of highly non-linear soliton pair dynamics.

Rational molecular and device design enables organic solar cells approaching 20% efficiency

For organic solar cells to be competitive, the light-absorbing molecules should simultaneously satisfy multiple key requirements, including weak-absorption charge transfer state, high dielectric constant, suitable surface energy, proper crystallinity, etc. However, the systematic design rule in molecules to achieve the abovementioned goals is rarely studied. In this work, guided by theoretical calculation, we present a rational design of non-fullerene acceptor o-BTP-eC9, with distinct photoelectric properties compared to benchmark BTP-eC9. o-BTP-eC9 based device has uplifted charge transfer state, therefore significantly reducing the energy loss by 41 meV and showing excellent power conversion efficiency of 18.7%. Moreover, the new guest acceptor o-BTP-eC9 has excellent miscibility, crystallinity, and energy level compatibility with BTP-eC9, which enables an efficiency of 19.9% (19.5% certified) in PM6:BTP-C9:o-BTP-eC9 based ternary system with enhanced operational stability.

On-water surface synthesis of electronically coupled 2D polyimide-MoS2 van der Waals heterostructure

The water surface provides a highly effective platform for the synthesis of two-dimensional polymers (2DP). In this study, we present an efficient on-water surface synthesis of crystalline monolayer 2D polyimide (2DPI) through the imidization reaction between tetra (4-aminophenyl) porphyrin (M1) and perylenetracarboxylic dianhydride (M2), resulting in excellent stability and coverage over a large area (tens of cm2). We further fabricate innovative organic-inorganic hybrid van der Waals heterostructures (vdWHs) by combining with exfoliated few-layer molybdenum sulfide (MoS2). High-resolution transmission electron microscopy (HRTEM) reveals face-to-face stacking between MoS2 and 2DPI within the vdWH. This stacking configuration facilitates remarkable charge transfer and noticeable n-type doping effects from monolayer 2DPI to MoS2, as corroborated by Raman spectroscopy, photoluminescence measurements, and field-effect transistor (FET) characterizations. Notably, the 2DPI-MoS2 vdWH exhibits an impressive electron mobility of 50 cm2/V·s, signifying a substantial improvement over pristine MoS2 (8 cm2/V·s). This study unveils the immense potential of integrating 2D polymers to enhance semiconductor device functionality through tailored vdWHs, thereby opening up exciting new avenues for exploring unique interfacial physical phenomena.

Hexaazatriphenylene-Based Two-Dimensional Conductive Covalent Organic Framework with Anisotropic Charge Transfer

The development of covalent organic frameworks (COFs) with efficient charge transport is of immense interest for applications in optoelectronic devices. To enhance COF charge transport properties, electroactive building blocks and dopants can be used to induce extended conduction channels. However, understanding their intricate interplay remains challenging. We designed and synthesized a tailor-made COF structure with electroactive hexaazatriphenylene (HAT) core units and planar dioxin (D) linkages, denoted as HD-COF. With the support of theoretical calculations, we found that the HAT units in the HD-COF induce strong, eclipsed π-π stacking. The unique stacking of HAT units and the weak in-plane conjugation of dioxin linkages leads to efficient anisotropic charge transport. We fabricated HD-COF films to minimize the grain boundary effect of bulk COFs, which resulted in enhanced conductivity. As a result, the HD-COF films showed an electrical conductivity as high as 1.25 S cm-1 after doping with tris(4-bromophenyl)ammoniumyl hexachloroantimonate.

Low-Temperature Alignment of Conjugated Polymers by Plasticizer-Aided Physical Rubbing

Rubbing-induced alignment of conjugated polymers is systematically investigated in terms of intra- and inter-molecular interaction. Various polymer films with a broad range of polymer chain rigidity are rubbed, and the degree of polymer chain alignment is quantitatively characterized. The rubbing technique effectively aligns crystalline domains in conjugated polymer films when the temperature approaches the critical rubbing temperature (T r c $T_{\mathrm{r}}^{\mathrm{c}}$ ), at which the rearrangement and the slip of polymer chains are possible. A polymer with significant intra-/inter-molecular interactions exhibits higherT r c $T_{\mathrm{r}}^{\mathrm{c}}$ , though quantitative analysis reveals an intermediately aligned state at temperature Tr ' lower thanT r c $T_{\mathrm{r}}^{\mathrm{c}}$ . This state originates from polymer chain aggregation in an amorphous domain. The intermediately aligned state can be controlled by plasticizer, which enables low-temperature alignment of high-mobility polymer film by reducing Tr ' to near 100 °C, increases the crystallinity, and improves the alignment effect at this state comparable to that of the completely aligned state obtained at extremely high temperatures.

Triggering the Donor-Acceptor Phase Segregation with Solid Additives Enables 16.5% Efficiency in All-Polymer Solar Cells

All-polymer solar cells have attracted considerable research interest due to their superior morphological stabilities, stretchability, and mechanical durability. However, the morphology optimization of the all-polymer bulk heterojunctions remains challenging due to the two long conjugated polymer chains, limiting its power conversion efficiency. Herein, we focus on the donor-acceptor phase segregation of an all-polymer active layer composed of PM6/PY-IT, a state-of-the-art all-polymer combination, by the introduction of volatile solid additives. Especially with 1,3-dibromo-5-chlorobenzene (DBCl) as the processing additive, we could effectively tune the miscibility between PM6 and PY-IT and thus optimize the phase segregation of the polymer donor and acceptor. Due to the synergetic effects on the favorable phase segregation and desired donor-acceptor distribution, the DBCl-treated devices feature the evident improvement of charge transport and collection, accompanied by the suppressed trap-assisted charge recombination. We consequently achieved a champion device efficiency of 16.5% (16.4% averaged), which is a 13% improvement compared with the control device without DBCl (14.6%). Our results highlight the importance of altering the miscibility of the polymer donor-acceptor pairs for practical applications of high-performance all-polymer solar cells.

Vertical Phase Regulation with 1,3,5-Tribromobenzene Leads to 18.5% Efficiency Binary Organic Solar Cells

The sequential deposition method assists the vertical phase distribution in the photoactive layer of organic solar cells, enhancing power conversion efficiencies. With this film coating approach, the morphology of both layers can be fine-tuned with high boiling solvent additives, as frequently applied in one-step casting films. However, introducing liquid additives can compromise the morphological stability of the devices due to the solvent residuals. Herein, 1,3,5-tribromobenzene (TBB) with high volatility and low cost, is used as a solid additive in the acceptor solution and combined thermal annealing to regulate the vertical phase in organic solar cells composed of D18-Cl/L8-BO. Compared to the control cells, the devices treated with TBB and those that underwent additional thermal processing exhibit increased exciton generation rate, charge carrier mobility, charge carrier lifetime, and reduced bimolecular charge recombination. As a result, the TBB-treated organic solar cells achieve a champion power conversion efficiency of 18.5% (18.1% averaged), one of the highest efficiencies in binary organic solar cells with open circuit voltage exceeding 900 mV. This study ascribes the advanced device performance to the gradient-distributed donor-acceptor concentrations in the vertical direction. The findings provide guidelines for optimizing the morphology of the sequentially deposited top layer to achieve high-performance organic solar cells.

Achieving ideal transistor characteristics in conjugated polymer semiconductors

Organic thin-film transistors (OTFTs) with ideal behavior are highly desired, because nonideal devices may overestimate the intrinsic property and yield inferior performance in applications. In reality, most polymer OTFTs reported in the literature do not exhibit ideal characteristics. Supported by a structure-property relationship study of several low-disorder conjugated polymers, here, we present an empirical selection rule for polymer candidates for textbook-like OTFTs with high reliability factors (100% for ideal transistors). The successful candidates should have low energetic disorder along their backbones and form thin films with spatially uniform energetic landscapes. We demonstrate that these requirements are satisfied in the semicrystalline polymer PffBT4T-2DT, which exhibits a reliability factor (~100%) that is exceptionally high for polymer devices, rendering it an ideal candidate for OTFT applications. Our findings broaden the selection of polymer semiconductors with textbook-like OTFT characteristics and would shed light upon the molecular design criteria for next-generation polymer semiconductors.

Balancing the Efficiency and Synthetic Accessibility of Organic Solar Cells with Isomeric Acceptor Engineering

With the continuous development of organic semiconductor materials and on-going improvement of device technology, the power conversion efficiencies (PCEs) of organic solar cells (OSCs) have surpassed the threshold of 19%. Now, the low production cost of organic photovoltaic materials and devices have become an imperative demand for its practical application and future commercialization. Herein, the feasibility of simplified synthesis for cost-effective small-molecule acceptors via end-cap isomeric engineering is demonstrated, and two constitutional isomers, BTP-m-4Cl and BTP-o-4Cl, are synthesized and compared in parallel. These two non-fullerene acceptors (NFAs) have very similar optoelectronic properties but nonuniform morphological and crystallographic characteristics. Consequently, the OSCs composed of PM6:BTP-m-4Cl realize PCE of 17.2%, higher than that of the OSCs with PM6:BTP-o-4Cl (≈16%). When ternary OSCs are fabricated with PM6:BTP-m-4Cl:BTP-o-4Cl, the averaged PCE value reaches 17.95%, presenting outstanding photovoltaic performance. Most excitingly, the figure of merit (FOM) values of PM6:BTP-m-4Cl, PM6:BTP-o-4Cl, and PM6:BTP-m-4Cl:BTP-o-4Cl based devices are 0.190, 0.178, and 0.202 respectively. The FOM values of these systems are all among the top ones of the current high-efficiency OSC systems, revealing high cost-effectiveness of the two NFAs. This work provides a general but accessible strategy to minimize the efficiency-cost gap and promises the economic prospects of OSCs.

Disordered Phase-Assisted Growth of Organic Semiconductor Crystals on Self-Assembled Monolayer Templates

Achieving high mobility and bias stability is a challenging obstacle in the advancement of organic thin-film transistors (OTFTs). To this end, the fabrication of high-quality organic semiconductor (OSC) thin films is critical for OTFTs. Self-assembled monolayers (SAMs) have been used as growth templates for high-crystalline OSC thin films. Despite significant research progress in the growth of OSC on SAMs, a detailed understanding of the growth mechanism of the OSC thin films on a SAM template is lacking, which has limited its use. In this study, the effects of the structure (thickness and molecular packing) of SAM on the nucleation and growth behavior of the OSC thin films were investigated. We found that disordered SAM molecules assisted in the surface diffusion of the OSC molecules and resulted in a small nucleation density and large grain size of the OSC thin films. Moreover, a thick SAM with disordered SAM molecules on the top was found to be beneficial for the high mobility and bias stability of the OTFTs.

Surface Passivation by Sulfur-Based 2D (TEA)2PbI4 for Stable and Efficient Perovskite Solar Cells

Perovskite solar cells (PSCs) with superior performance have been recognized as a potential candidate in photovoltaic technologies. However, defects in the active perovskite layer induce nonradiative recombination which restricts the performance and stability of PSCs. The construction of a thiophene-based 2D structure is one of the significant approaches for surface passivation of hybrid PSCs that may combine the benefits of the stability of 2D perovskite with the high performance of three-dimensional (3D) perovskite. Here, a sulfur-rich spacer cation 2-thiopheneethylamine iodide (TEAI) is synthesized as a passivation agent for the construction of a three-dimensional/two-dimensional (3D/2D) perovskite bilayer structure. TEAI-treated PSCs possess a much higher efficiency (20.06%) compared to the 3D perovskite (MA_0.9FA_0.1PbI₃) devices (17.42%). Time-resolved photoluminescence and femtosecond transient absorption spectroscopy are employed to investigate the effect of surface passivation on the charge carrier dynamics of the 3D perovskite. Additionally, the stability test of TEAI-treated perovskite devices reveals significant improvement in humid (RH ∼ 46%) and thermal stability as the sulfur-based 2D (TEA)₂PbI₄ material self-assembles on the 3D surface, making the perovskite surface hydrophobic. Our findings provide a reliable approach to improve device stability and performance successively, paving the way for industrialization of PSCs.

Willingness to vaccinate children against COVID-19 declined during the pandemic

OBJECTIVES

To document the level of vaccine hesitancy in caregivers' of children younger than 12 years of age over the course of the pandemic in Pediatric Emergency Departments (ED). Study design Ongoing multicenter, cross-sectional survey of caregivers presenting to 19 pediatric EDs in the USA, Canada, Israel, and Switzerland during first months of the pandemic (phase1), when vaccines were approved for adults (phase2) and most recently when vaccines were approved for children (phase3).

RESULTS

Willingness to vaccinate rate declined over the study period (59.7%, 56.1% and 52.1% in the three phases). Caregivers who are fully vaccinated, who have higher education, and those worried their child had COVID-19 upon arrival to the ED, were more likely to plan to vaccinate in all three phases. Mothers were less likely to vaccinate early in the pandemic, but this hesitancy attenuated in later phases. Older caregivers were more willing to vaccinate, and caregivers of older children were less likely to vaccinate their children in phase 3. During the last phase, willingness to vaccinate was lowest in those who had a primary care provider but did not rely on their advice for medical decisions (34%). Those with no primary care provider and those who do and rely on their medical advice, had similar rates of willingness to vaccinate (55.1% and 52.1%, respectively).

CONCLUSIONS

COVID-19 vaccine hesitancy is widespread and growing over time, and public health measures should further try to leverage identified factors associated with hesitancy in order to enhance vaccination rates among children.

Extremely Suppressed Energetic Disorder in a Chemically Doped Conjugated Polymer

Chemical doping can be used to tune the optoelectronic properties of conjugated polymers (CPs), extending their applications as conducting materials. Unfortunately, chemically doped CP films containing excess dopants exhibit an increase in energetic disorder upon structural alteration, and Coulomb interactions between charge carriers and dopants also affect such disorder. The increase in energetic disorder leads to a broadening of the density of states, which consequently impedes efficient charge transport in chemically doped CPs. However, the molecular origins that are inherently resistant to such incidental increase of energetic disorder in chemically doped CPs have not been sufficiently explored. Here, it is discovered that energetic disorder in chemically doped CPs can be suppressed to a level close to the theoretical limit. Indacenodithiophene-co-benzothiadiazole (IDTBT) doped with triethyloxonium hexachloroantimonate (OA) exhibits disorder-free charge-transport characteristics and band-like transport behavior with astonishing carrier mobility as a result of reinforced 1D intramolecular transport. Molecular structure of IDTBT provides a capability to lower the energetic disorder that generally arises from the inclusion of heterogeneous dopants. The results suggest the possibilities of implementing disorder-free CPs that exhibit excellent charge transport characteristics in the chemically doped state and satisfy a prerequisite for their availability in the industry.

Symmetry-Induced Ordered Assembly of a Naphthobisthiadiazole-Based Nonfused-Ring Electron Acceptor Enables Efficient Organic Solar Cells

Nonfused-ring electron acceptors (NFREAs) have received increasing attention for use in organic solar cells (OSCs) because of their synthetic simplicity and tunable optical spectra. However, their fundamental molecular interactions and the mechanism by which they govern the property-function relations of OSCs remain elusive. Here, to investigate the effects of the structural symmetry of NFREAs, two acceptor-donor-acceptor'-donor-acceptor (A-D-A'-D-A)-type NFREAs, 2,2'-(((naphtho[1,2-c:5,6-c']bis[1,2,5]thiadiazole-5,10-diylbis(4,4-bis(2-butyloctyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene-6,2-diyl))bis(methaneylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (NTz-4F) and 2,2'-(((benzo[c][1,2,5]thiadiazole-4,7-diylbis(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene-6,2-diyl))bis(methaneylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (BT-4F), are designed and synthesized. They have different A' cores: NTz-4F has a modified centrosymmetric NTz core, whereas BT-4F has a modified axisymmetric BT core. In pristine films, the NTz-4F, which has a centrosymmetric core, shows substantially enhanced intermolecular interaction and microstructural crystalline ordering compared with BT-4F, which has an axisymmetric core. Even in blends with poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8,-dione))] (PBDB-T), NTz-4F retains its highly crystalline structure, whereas BT-4F loses crystalline packing. These changes in NTz-4F result in increased electron transport and suppressed nonradiative voltage loss, resulting in a power conversion efficiency of 9.14% for PBDB-T:NTz-4F vs 7.18% for PBDB-T:BT-4F. This work demonstrates that centrosymmetric-structured cores are promising building blocks for high-performance NFREA-based OSCs.

An Electret-Powered Skin-Attachable Auditory Sensor that Functions in Harsh Acoustic Environments

Auditory sensors have shortcomings with respect to not only personalization with wearability and portability but also detecting a human voice clearly in a noisy environment or when a mask covers the mouth. In this work, an electret-powered and hole-patterned polymer diaphragm is exploited into a skin-attachable auditory sensor. The optimized charged electret diaphragm induces a voltage bias of >400 V against the counter electrode, which reduces the necessity of a bulky power source and enables the capacitive sensor to show high sensitivity (2.2 V Pa^-1 ) with incorporation of an elastomer nanodroplet seismic mass. The sophisticated capacitive structure with low mechanical damping enables a flat frequency response (80-3000 Hz) and good linearity (50-80 dB_SPL ). The hole-patterned electret diaphragms help the skin-attachable sensor detect only neck-skin vibration rather than dynamic air pressure, enabling a person's voice to be detected in a harsh acoustic environment. The sensor operates reliably even in the presence of surrounding noise and when the user is wearing a gas mask. Therefore, the sensor shows strong potential of a communication tool for disaster response and quarantine activities, and of diagnosis tool for vocal healthcare applications such as cough monitoring and voice dosimetry.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

POS1422 USE OF DISEASE MODIFYING ANTI-RHEUMATIC DRUGS AND RISK OF MULTIPLE MYELOMA IN PERSONS WITH RHEUMATOID ARTHRITIS

Background

Biologic therapies used in the management of rheumatoid arthritis (RA) target several cytokines that have been implicated in the pathogenesis of multiple myeloma (MM). Yet little is known about the association between use of biologic or targeted synthetic disease modifying anti-rheumatic drugs (b or tsDMARDs) in RA and the incidence of MM.

Objectives

Our objective was to estimate the association between b/tsDMARD use and the risk of MM among persons with RA using Veterans Health Administration (VHA) data. We hypothesized that b-/tsDMARD use is associated with a lower incidence of MM compared with conventional synthetic DMARDs (csDMARDs).

Methods

In this retrospective cohort study, we identified patients >18 years of age diagnosed with RA in any United States VHA facility from 1/1/2002 and 12/31/2018. All patients met the following inclusion criteria: 1) two or more International Classification of Diseases Version 9 or 10 (ICD9 or ICD10) codes for RA at least 7 days apart but no more than 365 days apart 2) a prescription for a csDMARD within 90 days of the first RA diagnosis 3) one inpatient or outpatient visit 30 days to 2 years preceding first RA diagnosis (indicating a regular user of VHA). Medication data was derived from the outpatient prescription fills, bar coded medication administration (BCMA), and intravenous (IV) data domains. The csDMARDs included in these analyses were: methotrexate, sulfasalazine, leflunomide, and hydroxychloroquine. The bDMARDs included were tumor necrosis factor inhibitors (TNFi) and non-TNFi biologics such as tocilizumab, rituximab, abatacept, and biosimilars; tsDMARD was tofacitinib. Patients with MM before the diagnosis of RA were excluded. Incident MM was determined by 1 or more ICD9/10 code or ICD-oncology codes. Multivariable Cox proportional hazards model were performed to estimate the hazard ratio for developing MM among those during and following the use of a b-/tsDMARD relative to b-/tsDMARD-naïve persons adjusting for age, gender, race, and ethnicity.

Results

27,540 veterans with RA met study eligibility criteria, of whom 8,322 (30%) had taken a b-/tsDMARD. Over the study period there were 77 incident MM over a total of 192,000 person years. There were 55 events in users of csDMARDs, an incidence rate (IR) of 0.40 (95% CI 0.30-0.52) per 1000 person-years and 22 in persons currently or formerly using b-/tsDMARDs (IR 0.41, 0.25-0.61 per 1000 person years). The unadjusted hazard ratio for MM following bDMARD use relative to csDMARD only use was 1.04 (0.63, 1.73), which increased to 1.28 (0.76, 2.16) after adjusting for demographic characteristics (Table 1).

Table 1.

Multivariable Cox proportional hazards model for association between use of disease modifying anti-rheumatic drugs and incident multiple myeloma.

Clinical characteristicHazards ratio (95% CI)csDMARDReferenceb-/tsDMARD use1.28 (0.76-2.16)Age*1.04 (1.02-1.07)Female0.58 (0.20-1.62)RaceReferenceWhite2.11 (1.15-3.86)Black0.70 (0.10-5.08)OtherHispanic Ethnicity0.71 (0.17-2.92)

Abbreviations: b-/tsDMARD- biologic or targeted synthetic disease modifying anti-rheumatic drug; CI: confidence interval

*Hazards ratio reflects risk per every 1-year increase in age

Model adjusted for age, gender, race, and ethnicity

Conclusion

In this nationwide VA study, we did not observe an association between bDMARD use and the incidence of MM. Of note, the median interval from initiation of a bDMARD to the end of follow-up was approximately 5.8 years, which does not allow for an examination of a possible longer term influence.

Disclosure of Interests

None declared

Investigating Brain White Matter in Football Players with and without Concussion Using a Biophysical Model from Multishell Diffusion MRI

BACKGROUND AND PURPOSE

There have been growing concerns around potential risks related to sports-related concussion and contact sport exposure to repetitive head impacts in young athletes. Here we investigate WM microstructural differences between collegiate football players with and without sports-related concussion.

MATERIALS AND METHODS

The study included 78 collegiate athletes (24 football players with sports-related concussion, 26 football players with repetitive head impacts, and 28 non-contact-sport control athletes), available through the Federal Interagency Traumatic Brain Injury Research registry. Diffusion metrics of diffusion tensor/kurtosis imaging and WM tract integrity were calculated. Tract-Based Spatial Statistics and post hoc ROI analyses were performed to test group differences.

RESULTS

Significantly increased axial kurtosis in those with sports-related concussion compared with controls was observed diffusely across the whole-brain WM, and some focal areas demonstrated significantly higher mean kurtosis and extra-axonal axial diffusivity in sports-related concussion. The extent of significantly different WM regions decreased across time points and remained present primarily in the corpus callosum. Similar differences in axial kurtosis were found between the repetitive head impact and control groups. Other significant differences were seen at unrestricted return-to-play with lower radial kurtosis and intra-axonal diffusivity in those with sports-related concussion compared with the controls, mainly restricted to the posterior callosum.

CONCLUSIONS

This study highlights the fact that there are differences in diffusion microstructure measures that are present not only between football players with sports-related injuries and controls, but that there are also measurable differences between football players with repetitive head impacts and controls. This work reinforces previous work showing that the corpus callosum is specifically implicated in sports-related concussion and also suggests this to be true for repetitive head impacts.

Effect of Electron-Withdrawing Chlorine Substituent on Morphological and Photovoltaic Properties of All Chlorinated D-A-Type Quinoxaline-Based Polymers

The choice of the chlorine (Cl) atom as an electron-withdrawing substituent in conjugated polymers leads to a higher potential in the commercialization of polymer solar cells than its fluorine counterpart because of the versatility and cost-effectiveness of the chlorination process. In addition, the population and location of Cl substituents can significantly influence the photovoltaic characteristics of polymers. In this study, three chlorinated quinoxaline-based polymers were invented to examine the numerical and positioning effects of the Cl atom on their photovoltaic characteristics. The number of Cl substituents in the reference polymer, PBCl-Qx, was adjusted to three: two Cl atoms in the benzodithiophene-type D unit and one Cl atom in the quinoxaline-type A unit. Subsequently, two more Cl atoms were selectively introduced at the 4- and 5-positions of the alkylated thiophene moieties at the 2,3-positions of the quinoxaline moiety in PBCl-Qx to obtain the additional polymers PBCl-Qx4Cl and PBCl-Qx5Cl, respectively. The conventional PBCl-Qx4Cl device exhibited a better power conversion efficiency (PCE) of 12.95% as compared to those of PBCl-Qx (12.44%) and PBCl-Qx5Cl (11.82%) devices. The highest PCE of the device with PBCl-Qx4Cl was ascribed to an enhancement in the open-circuit voltage and fill factor induced by the deeper energy level of the highest occupied molecular orbital and the favorable morphological features in its blended film with Y6.

A High-Fidelity Skin-Attachable Acoustic Sensor for Realizing Auditory Electronic Skin

Wearable auditory sensors are critical in user-friendly sound-recognition systems for smart human-machine interaction and the Internet of Things. However, previously reported wearable sensors have limited sound-sensing quality as a consequence of a poor frequency response and a narrow acoustic-pressure range. Here, a skin-attachable acoustic sensor is presented that has higher sensing accuracy in wider auditory field than human ears, with flat frequency response (15-10 000 Hz) and a good range of linearity (29-134 dB_SPL ) as well as high conformality to flexible surfaces and human skin. This high sound-sensing quality is achieved by exploiting the low residual stress and high processability of polymer materials in a diaphragm structure designed using acousto-mechano-electric modeling. Thus, this acoustic sensor shows high acoustic fidelity by sensing human-audible sounds, even loud sounds and low-frequency sounds that human ears cannot detect without distorting them. The polymer-based ultrasmall (<9 mm² ) and thin sensor maintains sound-detection quality on flexible substrates and in a wide temperature range (25 to 90 °C). The acoustic sensor shows a significant potential of auditory electronic skin, by recognizing voice successfully when the sensor attached on human skin is connected to a commercial mobile device running the latest artificial intelligence assistant.

Solution-Processable Semiconducting Conjugated Planar Network

After the emergence of graphene in the material science field, top-down and bottom-up studies to develop semiconducting organic materials with layered structures became highly active. However, most of them have suffered from poor processability, which hampers device fabrication and frustrates practical applications. Here, we suggest an unconventional approach to fabricating semiconducting devices, which avoids the processability issue. We designed a soluble amorphous network using a solution process to form a thin film on a substrate. We then employed heat treatment to develop a flattened organic structure in the thin film, as an active layer for organic thin-film transistors (TFTs). The fabricated TFTs showed good performance in both horizontal and vertical charge transport, suggesting a versatile and useful approach for the development of organic semiconductors.

Correction: Structure–property relationships of diketopyrrolopyrrole- and thienoacene-based A–D–A type hole transport materials for efficient perovskite solar cells

Correction for ‘Structure–property relationships of diketopyrrolopyrrole- and thienoacene-based A–D–A type hole transport materials for efficient perovskite solar cells’ by Gururaj P. Kini et al., New J. Chem., 2022, DOI: https://doi.org/10.1039/d2nj00294a.

Structure–property relationships of diketopyrrolopyrrole- and thienoacene-based A–D–A type hole transport materials for efficient perovskite solar cells

Two DPP-based hole-transporting materials with different aromatic π-bridges have been synthesized and tested for perovskite solar cells. Improved power conversion efficiency and stability were achieved by employing DPP-TT.

Cactus-Spine-Inspired Sweat-Collecting Patch for Fast and Continuous Monitoring of Sweat

A sweat sensor is expected to be the most appropriate wearable device for noninvasive healthcare monitoring. However, the practical use of sweat sensors is impeded by irregular and low sweat secretion rates. Here, a sweat-collecting patch that can collect sweat efficiently for fast and continuous healthcare monitoring is demonstrated. The patch uses cactus-spine-inspired wedge-shaped wettability-patterned channels on a hierarchical microstructured/nanostructured surface. The channel shape, in combination with the superhydrophobic/superhydrophilic surface materials, induces a unidirectional Laplace pressure that transports the sweat to the sensing area spontaneously even when the patch is aligned vertically. The patch demonstrates superior sweat-collecting efficiency and reduces the time required to fill the sensing area by transporting sweat almost without leaving it inside the channel. Therefore, a sensor based on the patch responds quickly to biochemicals in sweat, and the patch enables the continuous monitoring of changes in sweat biochemicals according to their changes in the wearer's blood.

Womens health-related quality of life substantially improves with tailored cardiac rehabilitation: a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background

Women have poorer outcomes from coronary heart disease (CHD) compared to men and participation in exercise-based cardiac rehabilitation (EBCR) offers an opportunity for improvement. However, synthesised evidence for women-specific patient-reported outcomes are often lacking. We aimed to synthesise HRQL outcomes from EBCR in women with CHD.

Methods

Four electronic databases (PUBMED, CINAHL, SCOPUS and Cochrane) were searched for studies reporting HRQL using validated measures in women attending EBCR. Two reviewers independently screened papers and extracted data. Random effects model (RevMan v5.4) was used for analysis.

Results

Eleven studies (1292 women participants) were included: six observational, three randomised controlled trials, and two quasi-experimental design. Seven studies were included in the meta-analyses. EBCR participation was associated with HRQL benefits in several domains of the Short-Form (SF-12 or 36). Improvements were greatest in Role Physical (MD 19.09 95% CI 2.37, 35.81), Physical Functioning (MD 10.43, 95% CI 2.60, 18.27) and Vitality (MD 9.59, 95% CI 0.31, 18.86). When tailored components were added to traditional EBCR, gains in HRQL were also observed, specifically in Bodily Pain (MD 9.82, 95% CI 4.43, 15.21), Role Physical (MD 8.48, 95% CI 1.31, 9.97), Vitality (MD 8.17, 95% CI 3.79, 12.55), General Health (MD 5.64, 95% CI 1.31, 9.97), and Physical Function (MD 5.61, 95% CI 0.83, 10.40) domains.

Conclusion

Women attending EBCR achieve clinically meaningful improvements in multiple areas of HRQL, and additional benefits were seen when strategies tailored to their needs and preferences were included. Future research should focus on promoting EBCR uptake in women.

POS1422 CORRELATES OF TESTING POSITIVE FOR SARS-COV-2 IN PATIENTS WITH RHEUMATIC AD MUSCULOSKELETAL DISEASES

Background:

Many studies on COVID-19 outcomes in patients with RMD have either restricted to COVID positive RMD patients or compared them to the general clinic population as a comparator. Given heterogeneity in behaviors and risks, clinical characteristics associated with a positive diagnosis among patients with RMD seeking testing for Sars-CoV-2 remain less well studied.

Objectives:

Among patients with RMD receiving a Sars-CoV-2 PCR test, we aimed to identify RMD-related factors associated with a positive test result.

Methods:

Among patients seen at least once in the University of Washington (UW) rheumatology clinics between March 2018 to March 2020, we reviewed electronic medical records to identify patients undergoing Sars-CoV-2 PCR testing from March 1 through October 31, 2020. Patients with RMD were categorized into two groups: those who tested positive for Sars-CoV-2 and those who tested negative. We randomly selected patients from the negative group in a 2:1 ratio for further data abstraction. Student’s t-test and Chi-squared tests were used to compare continuous and categorical variables, respectively, between the groups. To determine the correlates of testing positive for Sars-CoV-2, specifically RMD medication use and disease activity, we constructed different multivariable logistic regression models adjusted for age, sex, race/ethnicity, presence of comorbidities, body mass index, and smoking.

Results:

A total of 2768 RMD patients underwent SARS-CoV-2 PCR testing within the UW system, of whom 43 (1.5%) were positive at least once. Three patients with incomplete information were excluded. Patients who tested positive had higher prevalence of end stage renal disease (ESRD)/chronic kidney disease (CKD) (24% versus 11%), had higher rates of active disease (24% versus 20%), were older (>55 years) (mean age 57.3 versus 54.8 years), male (63% versus 55%), non-white race/ethnicity (32% versus 26%), and higher prevalence of multiple comorbidities (42% versus 31%) (Table 1). In the multivariable models, neither RMD medication use (versus no use, Table 1) nor high disease activity (vs low disease activity/remission) were statistically significantly associated with COVID-19 positivity. Among the 41 COVID-19 positive patients, a majority recovered without specific treatments, although approximately one third of the positive patients were hospitalized and three deaths were observed.

Conclusion:

In this study, patients who tested positive did not differ in many ways from those who tested negative.

Table 1.

Baseline characteristics of the patients prior to COVID testing

VariablesAll(N=126)COVID Positive (N=41)COVID Negative(N=85)P valueAge in years – mean (SD)55.6 (15.3)57.3 (16.3)54.8 (14.9)0.40Sex0.39 Male73 (57.9)26 (63.4)47 (55.3) Female53 (42.1)15 (36.6)38 (44.7)Race0.39 White89 (71.2)26 (63.4)63 (74.1) Other race35 (28.2)13 (31.7)22 (25.9) Missing2 (1.6)2 (4.9)0 (0.0)Rheumatic disease0.64 OA/Crystal/Fibromyalgia37 (29.4)11 (26.8)26 (30.6) RA/SpA32 (25.4)9 (22.0)23 (27.1) All others57 (45.2)21 (51.2)36 (42.3)Rheumatic disease activity0.57 Active27 (21.4)10 (24.4)17 (20.0) Not active99 (78.6)31 (75.6)68 (80.0)Co-morbidities  Diabetes mellitus (%)25 (19.8)9 (22.0)16 (18.8)0.68  Hypertension48 (38.1)20 (48.8)28 (32.9)0.09  Cardiovascular disease23 (18.3)9 (22.0)14 (16.5)0.46  Lung disease25 (19.8)10 (24.4)15 (17.7)0.37  Cancer10 (7.9)3 (7.3)7 (8.2)0.86  ESRD/CKD19 (15.1)10 (24.4)9 (10.6)0.04*

BMI: Body mass index; SD: Standard deviation; OA: Osteoarthritis; Crystal: Crystalline diseases; RA: Rheumatoid arthritis; SpA: Spondyloarthritis

Acknowledgements:

The work in this study was supported by grant UL1 TR002319 to Dr Singh from the Institute of Translational Health Sciences of the University of Washington.

Disclosure of Interests:

None declared

15.3% Efficiency All-Small-Molecule Organic Solar Cells Achieved by a Locally Asymmetric F, Cl Disubstitution Strategy

Single junction binary all-small-molecule (ASM) organic solar cells (OSCs) with power conversion efficiency (PCE) beyond 14% are achieved by using non-fullerene acceptor Y6 as the electron acceptor, but still lag behind that of polymer OSCs. Herein, an asymmetric Y6-like acceptor, BTP-FCl-FCl, is designed and synthesized to match the recently reported high performance small molecule donor BTR-Cl, and a record efficiency of 15.3% for single-junction binary ASM OSCs is achieved. BTP-FCl-FCl features a F,Cl disubstitution on the same end group affording locally asymmetric structures, and so has a lower total dipole moment, larger average electronic static potential, and lower distribution disorder than those of the globally asymmetric isomer BTP-2F-2Cl, resulting in improved charge generation and extraction. In addition, BTP-FCl-FCl based active layer presents more favorable domain size and finer phase separation contributing to the faster charge extraction, longer charge carrier lifetime, and much lower recombination rate. Therefore, compared with BTP-2F-2Cl, BTP-FCl-FCl based devices provide better performance with FF enhanced from 71.41% to 75.36% and J sc increased from 22.35 to 24.58 mA cm-2, leading to a higher PCE of 15.3%. The locally asymmetric F, Cl disubstitution on the same end group is a new strategy to achieve high performance ASM OSCs.

Aβ Accumulation in Vmo Contributes to Masticatory Dysfunction in 5XFAD Mice

Alzheimer's disease (AD) shows various symptoms that reflect cognitive impairment and loss of neural circuit integrity. Sensory dysfunctions such as olfactory and ocular pathology are also observed and used as indicators for early detection of AD. Although mastication is suggested to correlate with AD progression, changes in the masticatory system have yet to be established in transgenic animal models of AD. In the present study, we have assessed pathologic hallmarks of AD with the masticatory behavior of 5XFAD mice. We found that masticatory efficiency and maximum biting force were decreased in 5XFAD mice, with no significant change in general motor function. Immunohistochemical analysis revealed significant accumulation of Aβ (amyloid β), increased microglia number, and cell death in Vmo (trigeminal motor nucleus) as compared with other cranial motor nuclei that innervate the orofacial region. Masseter muscle weight and muscle fiber size were also decreased in 5XFAD mice. Taken together, our results demonstrate that Aβ accumulation in Vmo contributes to masticatory dysfunction in 5XFAD mice, suggesting a close association between masticatory dysfunction and dementia.

A new concept for temporal gating of synchrotron X-ray pulses

A new concept for temporal gating of synchrotron X-ray pulses based on laser-induced thermal transient gratings is presented. First experimental tests of the concept yield a diffraction efficiency of 0.18%; however, the calculations indicate a theoretical efficiency and contrast of >30% and 10-5, respectively. The full efficiency of the pulse picker has not been reached yet due to a long-range thermal deformation of the sample after absorption of the excitation laser. This method can be implemented in a broad spectral range (100 eV to 20 keV) and is only minimally invasive to an existing setup.

GW190521: A Binary Black Hole Merger with a Total Mass of 150 M_{⊙}

On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85_{-14}^{+21}  M_{⊙} and 66_{-18}^{+17}  M_{⊙} (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65  M_{⊙}. We calculate the mass of the remnant to be 142_{-16}^{+28}  M_{⊙}, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is 5.3_{-2.6}^{+2.4}  Gpc, corresponding to a redshift of 0.82_{-0.34}^{+0.28}. The inferred rate of mergers similar to GW190521 is 0.13_{-0.11}^{+0.30}  Gpc^{-3} yr^{-1}.

MR Susceptibility Imaging with a Short TE (MR-SISET): A Clinically Feasible Technique to Resolve Thalamic Nuclei

The thalamus consists of several functionally distinct nuclei, some of which serve as targets for functional neurosurgery. Visualization of such nuclei is a major challenge due to their low signal contrast on conventional imaging. We introduce MR susceptibility imaging with a short TE, leveraging susceptibility differences among thalamic nuclei, to automatically delineate 15 thalamic subregions. The technique has the potential to enable direct targeting of thalamic nuclei for functional neurosurgical guidance.

0076 The Role of Preoptic Area GABAergic Axonal Projections to Tuberomammillary Nucleus in Sleep Homeostasis

Introduction

Sleep deprivation has profound widespread physiological effects including cognitive impairment, compromised immune system function and increased risk of cardiovascular disease. The preoptic area (POA) of the hypothalamus contains sleep-active GABAergic neurons that respond to sleep homeostasis. We have shown that activation of POA GABAergic axons innervating the tuberomammillary nucleus (TMN, GABAergicPOA -&gt;TMN) are critical for sleep regulation but it is unknown if these projections modulate sleep homeostasis.

Methods

To monitor in vivo neural activity of GABAergicPOA -&gt;TMN projection neurons during sleep deprivation and rebound, fiber photometry was used. GAD2-Cre mice (n=6) were injected with AAV-DIO-GCaMP6S into the POA and an optic fiber was implanted into the TMN. An electroencephalogram (EEG) and electromyography (EMG) implant was mounted upon the skull to identify brain states. Calcium activity was measured for six hours starting at ZT4. Each mouse was recorded for three days to establish baseline sleep calcium activity with at least two days between sessions. During sleep deprivation sessions, an experimenter sleep deprived each mouse starting at ZT0 for six hours by gently brushing the animal with a small paintbrush to maintain wakefulness and minimize the stress to the animal.

Results

During baseline sleep recordings, GABAergicPOA -&gt;TMN projection neurons are most active during sleep (NREM and REM) which is maintained until wake onset. As sleep pressure increases, GABAergicPOA -&gt;TMN projection neurons display gradual increase in neural activity compared to time-matched points during baseline sleep recordings. Once mice were permitted to enter sleep rebound, GABAergicPOA -&gt;TMN projection neurons gradually displayed decreased activity as sleep pressure eased.

Conclusion

GABAergicPOA -&gt;TMN projection neurons show a strong increase in activity to drive homeostatic sleep need during periods of increased sleep pressure but subside once this pressure is reduced.

Support

This work is supported by NIH grant R01-NS-110865.

0154 Role of Noradrenergic Projection to the Preoptic Area in Regulation of Arousal

Introduction

Locus coeruleus (LC) is a noradrenergic nucleus in the brainstem involved in the regulation of attention, arousal, mood and sensory gating. LC projects to multiple brain regions and recent development of novel systems neuroscience tools allows the dissection of projection-specific LC function in more detail. One of the regions with noradrenergic projection is the preoptic area of the hypothalamus (POA). POA has been shown to contain neurons that are important for regulating sleep, and we have examined the function of the LC projection to the POA in sleep and arousal.

Methods

We used optogenetics, chemogenetics, fiber photometry and in vivo electrophysiology to study the function of LC noradrenergic projection to the POA.

Results

Norepinephrine release in the POA fluctuates with brain state changes indicating that the LC to POA projection may be involved in regulating sleep and arousal. Optogenetic stimulation of LC fibers in the POA promotes wakefulness. Furthermore, optogenetic stimulation of the LC fibers in the POA modulates the activity of sleep- and wake-active neurons.

Conclusion

We have identified the role of the LC noradrenergic projection to the POA in the regulation of brain states. Stimulation of the LC fibers in the POA promotes wakefulness and modulates the activity dynamics of sleep- and wake-active neurons in the POA. Our results provide more detailed information about the role of this specific projection, which has been known to exist for a long time, but with insufficient in vivo evidence of its precise function.

Support

Sigrid Juselius foundation, Alfred P. Sloan Research Fellowship in Neuroscience, The Whitehall foundation grant, McCabe Fund Award, NARSAD Young Investigator Award.

0074 Inhibitory Neurons in the Dorsomedial Medulla Promote REM Sleep

Introduction

The neural circuits controlling rapid eye movement (REM) sleep, and in particular the role of the medulla in regulating this brain state, remains an active area of study. Previous electrophysiological recordings in the dorsomedial medulla (DM) and electrical stimulation experiments suggested an important role of this area in the control of REM sleep. However the identity of the involved neurons and their precise role in REM sleep regulation are still unclear.

Methods

The properties of DM GAD2 neurons in mice were investigated through stereotaxic injection of CRE-dependent viruses in conjunction with implantation of electrodes for electroencephalogram (EEG) and electromyogram (EMG) recordings and optic fibers. Experiments included in vivo calcium imaging (fiber photometry) across sleep and wake states, optogenetic stimulation of cell bodies, chemogenetic excitation and suppression (DREADDs), and connectivity mapping using viral tracing and optogenetics.

Results

Imaging the calcium activity of DM GAD2 neurons in vivo indicates that these neurons are most active during REM sleep. Optogenetic stimulation of DM GAD2 neurons reliably triggered transitions into REM sleep from NREM sleep. Consistent with this, chemogenetic activation of DM GAD2 neurons increased the amount of REM sleep while inhibition suppressed its occurrence and enhanced NREM sleep. Anatomical tracing revealed that DM GAD2 neurons project to several areas involved in sleep / wake regulation including the wake-promoting locus coeruleus (LC) and the REM sleep-suppressing ventrolateral periaquaductal gray (vlPAG). Optogenetic activation of axonal projections from DM to LC, and DM to vlPAG was sufficient to induce REM sleep.

Conclusion

These experiments demonstrate that DM inhibitory neurons expressing GAD2 powerfully promote initiation of REM sleep in mice. These findings further characterize the dorsomedial medulla as a critical structure involved in REM sleep regulation and inform future investigations of the REM sleep circuitry.

Support

R01 HL149133

0071 A Medullary Circuit Controlling REM Sleep

Introduction

Rapid eye movement (REM) sleep is a distinct brain state known for its association with vivid dreaming in humans, though it is also crucial for other mental processes such as memory consolidation and emotion regulation. REM sleep is punctuated by phasic neurophysiological events known as pontine (P)-waves, which are thought to contribute to the cognitive functions of REM sleep. However, little is known about the neural circuits regulating these P-waves, or those responsible for initiating REM sleep itself. Here, we show that a yet unstudied population of medullary neurons expressing corticotropin-releasing-hormone (CRH) are important for controlling both the induction of REM sleep and its phasic events.

Methods

To measure the endogenous activity of CRH+ neurons in the dorsomedial medulla (dmM), we injected the calcium indicator GCaMP6 in the dmM of CRH-Cre mice. To optogenetically manipulate dmM CRH+ neuron activity, we delivered either an excitatory (ChR2) or inhibitory (iC++) opsin to the dmM of CRH-Cre mice. To record P-waves, we implanted microelectrodes to record local field potentials in the subcoeruleus region of the pons.

Results

Fiber photometry recordings showed that dmM CRH+ neurons are selectively active during REM sleep, and optogenetic stimulation and inhibition of this population is sufficient to promote and reduce REM sleep, respectively. Additionally, dmM CRH+ neuron activity is correlated with P-waves in the pons, and optogenetic activation of dmM CRH+ cells reliably triggers P-waves during REM sleep. Finally, histological examination of fluorescently labeled dmM CRH+ axons revealed strong projections to several pontine areas involved in P-wave generation as well as modulation of the theta rhythm during REM sleep.

Conclusion

Our results suggest that dmM CRH+ neurons are involved in controlling REM sleep initiation as well as phasic events within REM sleep. These neurons thus constitute an important component of the brainstem circuitry regulating REM sleep.

Support

National Institutes of Health (R01 HL149133)