An objective diagnosis of gout and calcium pyrophosphate deposition disease with machine learning of Raman spectra acquired in a point-of-care setting.

OBJECTIVE: Raman spectroscopy is proposed as a next-generation method for the identification of monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals in synovial fluid. As the interpretation of Raman spectra requires specific expertise, the method is not directly applicable for clinicians. We developed an approach to demonstrate that the identification process can be automated with the use of machine learning techniques. The developed system is tested in a point-of-care-setting at our outpatient rheumatology department. METHODS: We collected synovial fluid samples from 446 patients with various rheumatic diseases from three centra. We analyzed all samples with our Raman spectroscope and used 246 samples for training and 200 samples for validation. Trained observers classified every Raman spectrum as MSU, CPP or else. We designed two one-against-all classifiers, one for MSU and one for CPP. These classifiers consisted of a principal component analysis model followed by a support vector machine. RESULTS: The accuracy for classification of CPP using the 2023 ACR/EULAR CPPD classification criteria was 96.0% (95% CI 92.3-98.3), while the accuracy for classification of MSU with using the 2015 ACR/EULAR gout classification criteria was 92.5% (95% CI 87.9-95.7). Overall, the accuracy for classification of pathological crystals was 88.0% (95% CI 82.7-92.2). The model was able to discriminate between pathologic crystals, artifacts, and other particles such as microplastics. CONCLUSION: We here demonstrate that potentially complex Raman spectra from clinical patient samples can be successfully classified by a machine learning approach, resulting in an objective diagnosis independent of the opinion of the medical examiner.

Depletion rates of O2-naphthenic acids from oil sands process-affected water in wetland microcosms.

Treatment wetland microcosms were constructed to evaluate the fate of O2-naphthenic acids in microcosm reactors containing OSPW only (i.e., natural attenuation), OSPW with peat soil (sorption and microbial degradation), and cattail microcosm reactors (plant-mediated uptake and biotransformation). Depletion in OSPW occurs by mechanisms of natural attenuation, sorption and microbial degradation, and plant-mediated uptake and biotransformation. The average rate of depletion for O2-naphthenic acids was 0.005 (SD 0.010) per day in OSPW only, 0.029 (SD 0.013) per day in OSPW with peat soil, and 0.043 (SD 0.013) per day in cattail microcosm reactors. Slow rates of depletion from OSPW by natural attenuation highlight the need to develop effective remediation strategies for OSPW, and the increase in rates of depletion for cattail microcosm reactors highlights the importance of wetland vegetation in supporting naphthenic acid removal from OSPW. Reactors containing OSPW with peat soil showed the greatest increase in rates of O2-naphthenic acid depletion for lower molecular weight congeners compared to reactors with OSPW only. Cattail microcosm reactors showed the greatest increase in the rates of O2-naphthenic acid depletion for higher molecular weight congeners compared to reactors with OSPW and peat soil.

Fetoscopic laser photocoagulation: a medically reasonable treatment option in the management of types II and III vasa previa.

Vasa previa is a condition where unprotected fetal vessels cross the cervix within the membranes, posing a considerable risk of fetal death or severe morbidity if the membranes rupture before or during delivery. There has not been a definitive in utero treatment for this condition. Patients are typically closely monitored and hospitalized in the early third trimester and scheduled for cesarean delivery before term. This approach poses considerable physical, social, psychological, and financial challenges for pregnant patients and their families. Furthermore, fetal vessel rupture may lead to severe hypoxic-ischemic injury and consequent neurodevelopmental impairment. Finally, babies delivered early due to vasa previa may face both the short- and long-term consequences of prematurity. Recently, fetoscopic laser photocoagulation using a single-port fetoscope has emerged as a potential therapeutic option for patients with types II and III vasa previa. This innovative approach aims to reduce hospital stays, increases the chance of successful vaginal delivery, and potentially allows pregnancies to reach full term, providing lifelong benefits for the infant. Preliminary clinical studies on human subjects have demonstrated promising results concerning the feasibility, safety, and efficacy of this intervention for a subset of patients with types II and III vasa previa. After reviewing the current state of the art, we argued that offering fetoscopic laser photocoagulation in specialized centers under IRB supervision meets the ethical obligations of beneficence and non-maleficence for both pregnant and fetal patients, as well as the autonomy-based obligations for pregnant patients.

Dysglycemia and liver lipid content determine the relationship of insulin resistance with hepatic OXPHOS capacity in obesity.

BACKGROUND & AIMS: Hepatic mitochondrial respiration is higher in steatosis, but lower in overt type 2 diabetes. We hypothesized that hepatic OXPHOS capacity increases with a greater degree of insulin resistance in obesity, independent of other metabolic diseases. METHODS: We analysed 65 humans without diabetes (BMI 50±7 kg/m2, HbA1c 5.5±0.4%) undergoing bariatric surgery. MASLD stages were assessed by histology, whole-body insulin sensitivity (PREDIcted-M index) by oral glucose tolerance tests, and maximal ADP-stimulated mitochondrial OXPHOS capacity by high-resolution respirometry of liver samples. RESULTS: Prediabetes was present in 30 participants, and MASLD in 46 participants. Thereof, 25 had metabolic dysfunction-associated steatohepatitis (MASH), and seven had F2-F3 fibrosis. While simple regression did not detect an association of insulin sensitivity with hepatic OXPHOS capacity, interaction analyses revealed that the regression coefficient of OXPHOS capacity depended on fasting plasma glucose (FPG) and liver lipid content. Interestingly, the respective slopes were negative for FPG ≤100 mg/dl, but positive for FPG >100 mg/dl. Liver lipid content displayed similar behavior, with a threshold value of 24%. Post-challenge glycemia affected the association between insulin sensitivity and OXPHOS capacity normalized for citrate synthase activity. Presence of prediabetes affected hepatic insulin signaling, mitochondrial dynamics and fibrosis prevalence, while the presence of MASLD related to higher biomarkers of hepatic inflammation, cell damage and lipid peroxidation in people with normal glucose tolerance. CONCLUSIONS: Rising liver lipid contents and plasma glucose concentrations, even in the non-diabetic range, are associated with a progressive decline of hepatic mitochondrial adaptation in people with obesity and insulin resistance. CLINTRIALS. GOV IDENTIFIER: NCT01477957.

Protein tyrosine phosphatase 1B in metabolic and cardiovascular diseases: from mechanisms to therapeutics.

Protein Tyrosine Phosphatase 1B (PTP1B) has emerged as a significant regulator of metabolic and cardiovascular disease. It is a non-transmembrane protein tyrosine phosphatase that negatively regulates multiple signaling pathways integral to the regulation of growth, survival, and differentiation of cells, including leptin and insulin signaling, which are critical for development of obesity, insulin resistance, type 2 diabetes, and cardiovascular disease. Given PTP1B's central role in glucose homeostasis, energy balance, and vascular function, targeted inhibition of PTP1B represents a promising strategy for treating these diseases. However, challenges, such as off-target effects, necessitate a focus on tissue-specific approaches, to maximize therapeutic benefits while minimizing adverse outcomes. In this review, we discuss molecular mechanisms by which PTP1B influences metabolic and cardiovascular functions, summarize the latest research on tissue-specific roles of PTP1B, and discuss the potential for PTP1B inhibitors as future therapeutic agents.

Associations of Rest-Activity Rhythm Disturbances With Stroke Risk and Poststroke Adverse Outcomes.

BACKGROUND: Many disease processes are influenced by circadian clocks and display ~24-hour rhythms. Whether disruptions to these rhythms increase stroke risk is unclear. We evaluated the association between 24-hour rest-activity rhythms, stroke risk, and major poststroke adverse outcomes. METHODS AND RESULTS: We examined ~100 000 participants from the UK Biobank (aged 44-79 years; ~57% women) assessed with actigraphy (6-7 days) and 5-year median follow-up. We derived (1) most active 10-hour activity counts across the 24-hour cycle and the timing of its midpoint timing; (2) the least active 5-hour count and its midpoint; (3) relative amplitude; (4) interdaily stability; and (5) intradaily variability, for stability and fragmentation of the rhythm. Cox proportional hazard models were constructed for time to (1) incident stroke (n=1652) and (2) poststroke adverse outcomes (dementia, depression, disability, or death). Suppressed relative amplitude (lowest quartile [quartile 1] versus the top quartile [quartile 4]) was associated with stroke risk (hazard ratio [HR], 1.61 [95% CI, 1.35-1.92]; P<0.001) after adjusting for demographics. Later most active 10-hour activity count midpoint timing (14:00-15:26; HR, 1.26 [95% CI, 1.07-1.49]; P=0.007) also had higher stroke risk than earlier (12:17-13:10) participants. A fragmented rhythm (intradaily variability) was also associated with higher stroke risk (quartile 4 versus quartile 1; HR, 1.26 [95% CI, 1.06-1.49]; P=0.008). Suppressed relative amplitude was associated with risk for poststroke adverse outcomes (quartile 1 versus quartile 4; HR, 2.02 [95% CI, 1.46-2.48]; P<0.001). All associations were independent of age, sex, race, obesity, sleep disorders, cardiovascular diseases or risks, and other comorbidity burdens. CONCLUSIONS: Suppressed 24-hour rest-activity rhythm may be a risk factor for stroke and an early indicator of major poststroke adverse outcomes.

Semi-automated reproducible target transfer for cardiac radioablation - A multi-center cross-validation study within the RAVENTA trial.

BACKGROUND: Stereotactic arrhythmia radioablation (STAR) is a therapeutic option for ventricular tachycardia (VT) where catheter-based ablation is not feasible or has previously failed. Target definition and its transfer from electro-anatomic maps (EAM) to radiotherapy treatment planning systems (TPS) is challenging and operator-dependent. Software solutions have been developed to register EAM with cardiac CT and semi-automatically transfer 2D target surface data into 3D CT volume coordinates. Results of a cross-validation study of two conceptually different open-source software solutions using data from the RAVENTA trial (NCT03867747) are reported. METHODS: Clinical Target Volumes (CTVs) were created from target regions delineated on EAM using two conceptually different approaches by separate investigators on data of 10 patients, blinded to each other's results. Targets were transferred using 3D-3D registration and 2D-3D registration, respectively. The resulting CTVs were compared in a core-lab using two complementary analysis software packages for structure similarity and geometric characteristics. RESULTS: Volumes and surface areas of the CTVs created by both methods were comparable: 14.88 ±â€¯11.72 ml versus 15.15 ±â€¯11.35 ml and 44.29 ±â€¯33.63 cm2 versus 46.43 ±â€¯35.13 cm2. The Dice-coefficient was 0.84 ±â€¯0.04; median surface-distance and Hausdorff-distance were 0.53 ±â€¯0.37 mm and 6.91 ±â€¯2.26 mm, respectively. The 3D-center-of-mass difference was 3.62 ±â€¯0.99 mm. Geometrical volume similarity was 0.94 ±â€¯0.05 %. CONCLUSION: The STAR targets transferred from EAM to TPS using both software solutions resulted in nearly identical 3D structures. Both solutions can be used for QA (quality assurance) and EAM-to-TPS transfer of STAR-targets. Semi-automated methods could potentially help to avoid mistargeting in STAR and offer standardized workflows for methodically harmonized treatments.

Economically optimized forage utilization choices in drylands for adapting to economic, ecological, and climate stress.

Improving the economic performance of range forage in drylands internationally faces challenges from economic, ecological, and climate stress. Stakeholders in these drylands wish to protect range forage ecosystems while assuring economic viability of ranching. Despite several recent research achievements, little work to date has integrated relationships among precipitation, grazing pressure, animal performance, and forage production to protect ranching incomes faced with economic, ecological, and climate stress in dryland areas. This work addresses that gap by developing an empirical mathematical programming model for optimizing economic performance of livestock grazing on range forage ecosystems that adapt to several stressors. Its unique contribution is to formulate and apply a ranch income optimization model calibrated using positive mathematical programming. The model replicates observed economic, forage, and climate conditions while accounting for interacting relations among stocking rates, forage conditions, grazing pressure, animal performance, and ranch economic productivity. Results show ranch incomes ranging from about $5 to $88 per acre and marginal values of forage ranging from $0.01 to $0.12 per pound of forage, depending on economic, ecological, and climate conditions. Results reveal how all these stressors affect economically optimized choices of grazing levels, ranch income, and economic values of forage for a range of six biomes seen in the US west. Results help livestock ranchers to adjust stocking and forage choices as well as farm policymakers who seek flexible government programs to adapt to changes in economic, ecological, and climate conditions. The work's importance comes from applicability to forage management problems in dry regions internationally.

A polyphosphazene elastomer containing 2,2,2-trifluoroethoxy groups as a dielectric in electrically responsive soft actuators.

The adaptive structure and excellent actuation of dielectric elastomer actuators (DEAs) make them promising candidates for soft robotics, haptic interfaces and artificial muscles. A wide variety of elastomers have been synthesised and investigated as dielectrics. Inorganic polymers such as polysiloxanes and polyphosphazenes have a low glass transition temperature. While polydimethylsiloxane (PDMS) has made its way into DEAs, the latter has received little attention in this field. Here, we present a dielectric elastomer based on polyphosphazene modified with 2,2,2,-trifluoroethoxy groups as the dielectric, which exhibits a dielectric permittivity two times higher than polydimethylsiloxanes (PDMS), excellent elasticity and a high dielectric breakdown field. These properties enable fast, reliable actuation and higher electrostatic forces than conventional PDMS. The actuators can withstand repeated actuation cycles and are suitable for long-term reliability applications.

Impact of the Novel MRI Contrast Agent Gadopiclenol on Radiotherapy Decision Making in Patients With Brain Metastases.

PURPOSE: The aim of this study was to assess the effect of gadopiclenol versus gadobenate dimeglumine contrast-enhanced magnetic resonance imaging (MRI) on decision-making between whole-brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS) for treatment of brain metastases (BMs). METHODS: Patients with BMs underwent 2 separate MRI examinations in a double-blind crossover phase IIb comparative study between the MRI contrast agents gadopiclenol and gadobenate dimeglumine, both administered at 0.1 mmol/kg. The imaging data of a single site using identical MRI scanners and protocols were included in this post hoc analysis. Patients with 1 or more BMs in any of both MRIs were subjected to target volume delineation for treatment planning. Two radiation oncologists contoured all visible lesions and decided upon SRS or WBRT, according to the number of metastases. For each patient, SRS or WBRT treatment plans were calculated for both MRIs, considering the gross target volume (GTV) as the contrast-enhancing aspects of the tumor. Mean GTVs and volume of healthy brain exposed to 12 Gy (V12), as well as Dice similarity coefficient scores, were obtained. The Spearman rank (ρ) correlation was additionally calculated for assessing linear differences. Three different expert radiation oncologists blindly rated the contrast enhancement for contouring purposes. RESULTS: Thirteen adult patients were included. Gadopiclenol depicted additional BM as compared with gadobenate dimeglumine in 7 patients (54%). Of a total of 63 identified metastatic lesions in both MRI sets, 3 subgroups could be defined: A, 48 (24 pairs) detected equal GTVs visible in both modalities; B, 13 GTVs only visible in the gadopiclenol set (mean ± SD, 0.16 ± 0.37 cm3); and C, 2 GTVs only visible in the gadobenate dimeglumine set (mean ± SD, 0.01 ± 0.01). Treatment indication was changed for 2 (15%) patients, 1 from no treatment to SRS and for 1 from SRS to WBRT. The mean GTVs and brain V12 were comparable between both agents (P = 0.694, P = 0.974). The mean Dice similarity coefficient was 0.70 ± 0.14 (ρ = 0.82). According to the readers, target volume definition was improved in 63.9% of cases (23 of 36 evaluations) with gadopiclenol and 22.2% with gadobenate dimeglumine (8 of 36), whereas equivalence was obtained in 13.9% (5 of 36). CONCLUSIONS: Gadopiclenol-enhanced MRI improved BM detection and characterization, with a direct impact on radiotherapy treatment decision between WBRT and SRS. Additionally, a more exact target delineation and planning could be performed with gadopiclenol. A prospective evaluation in a larger cohort of patients is required to confirm these findings.

Penetration Thresholds of Porcine Limbs for Low Sectional Density Projectiles in High-Rate Impact.

INTRODUCTION: With similar prevalence to injuries from fires, stings, and natural disasters, soft tissue injuries may occur from fireworks, industrial accidents, or other explosives. Surgeons are less familiar with treating high-velocity penetration from small debris, which may increase the chance of infection and subsequent fatality. Penetration risk curves have been developed to predict V50, the velocity with 50% probability of penetration, for various sized projectiles. However, there has been limited research using nonmetallic materials to achieve lower density projectiles less than 1 g cm-2, such as sand or rocks. MATERIAL AND METHODS: To emulate the size and density of these energized particles, 14 ball bearings of stainless steel, silicon nitride, or Delrin acetal plastic ranging from 1.59 mm (1/16") to 9.53 mm (3/8") with sectional densities between 0.3 g cm-2 and 5 g cm-2 were launched toward porcine legs at a range of velocities to determine the penetration thresholds. High-speed videography was captured laterally at 40 kHz and impact velocity was captured using a physics-based tracking software. A generalized linear model with repeated measures and a logit link function was used to predict probability of penetration for each projectile. A total of 600 impacts were conducted to achieve at least 15 penetrating impacts for each projectile over a range of velocities. RESULTS: Higher impact velocities were required to penetrate the skin as sectional density of the projectile decreased, and the relationship between velocity and sectional density exhibited an exponential relationship (V50, $ = 184.6*S{D^{ - 0.385}}$, R2 = 0.95) with substantial change for nonlinearity in sectional densities ranging from 0.3 g cm-2 to 1 g cm-2. Compared to previous studies, the empirical relationship was consistent in the linear region (2-5 g cm-2), and novel experimentation filled in the gaps for sectional densities less than 1 g cm-2, which expressed more nonlinearity than previously estimated. For low-density projectiles with diameters of 1.59 (1/16") or 3.18 (1/8"), 32 impacts were lodged into the epidermis but did not penetrate through the dermis; however, penetration was defined as displacement into or through the dermis. CONCLUSIONS: These experimental results may be used to develop and validate finite element simulations of low-density projectile impacts to address complex, multivariate loading conditions for the development of protective clothing to reduce wounding and subsequent infection rates.

The unfolded protein response sensor PERK mediates mechanical stress-induced maturation of focal adhesion complexes in glioblastoma cells.

Stiffening of the brain extracellular matrix (ECM) in glioblastoma promotes tumor progression. Previously, we discovered that protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) plays a role in glioblastoma stem cell (GSC) adaptation to matrix stiffness through PERK/FLNA-dependent F-actin remodeling. Here, we examined the involvement of PERK in detecting stiffness changes via focal adhesion complex (FAC) formation. Compared to control GSCs, PERK-deficient GSCs show decreased vinculin and tensin expression, while talin and integrin-ß1 remain constant. Furthermore, vimentin was also reduced while tubulin increased, and a stiffness-dependent increase of the differentiation marker GFAP expression was absent in PERK-deficient GSCs. In conclusion, our study reveals a novel role for PERK in FAC formation during matrix stiffening, which is likely linked to its regulation of F-actin remodeling.

A Protocol to Determine Circadian Phase by At-Home Salivary Dim Light Melatonin Onset Assessment.

Internal circadian phase assessment is increasingly acknowledged as a critical clinical tool for the diagnosis, monitoring, and treatment of circadian rhythm sleep-wake disorders and for investigating circadian timing in other medical disorders. The widespread use of in-laboratory circadian phase assessments in routine practice has been limited, most likely because circadian phase assessment is not required by formal diagnostic nosologies, and is not generally covered by insurance. At-home assessment of salivary dim light melatonin onset (DLMO, a validated circadian phase marker) is an increasingly accepted approach to assess circadian phase. This approach may help meet the increased demand for assessments and has the advantages of lower cost and greater patient convenience. We reviewed the literature describing at-home salivary DLMO assessment methods and identified factors deemed to be important to successful implementation. Here, we provide specific protocol recommendations for conducting at-home salivary DLMO assessments to facilitate a standardized approach for clinical and research purposes. Key factors include control of lighting, sampling rate, and timing, and measures of patient compliance. We include findings from implementation of an optimization algorithm to determine the most efficient number and timing of samples in patients with Delayed Sleep-Wake Phase Disorder. We also provide recommendations for assay methods and interpretation. Providing definitive criteria for each factor, along with detailed instructions for protocol implementation, will enable more widespread adoption of at-home circadian phase assessments as a standardized clinical diagnostic, monitoring, and treatment tool.

Autofluorescence-based tissue characterization enhances clinical prospects of light-sheet-microscopy.

Light sheet fluorescence microscopy (LSFM) is a transformative imaging method that enables the visualization of non-dissected specimen in real-time 3D. Optical clearing of tissues is essential for LSFM, typically employing toxic solvents. Here, we test the applicability of a non-hazardous alternative, ethyl cinnamate (ECi). We comprehensively characterized autofluorescence (AF) spectra in diverse murine tissues-ocular globe, knee, and liver-employing LSFM under various excitation wavelengths (405-785 nm) to test the feasibility of unstained samples for diagnostic purposes, in particular regarding percutaneous biopsies, as they constitute to most harvested type of tissue sample in clinical routine. Ocular globe structures were best discerned with 640 nm excitation. Knee tissue showed complex variation in AF spectra variation influenced by tissue depth and structure. Liver exhibited a unique AF pattern, likely linked to vasculature. Hepatic tissue samples were used to demonstrate the compatibility of our protocol for antibody staining. Furthermore, we employed machine learning to augment raw images and segment liver structures based on AF spectra. Radiologists rated representative samples transferred to the clinical assessment software. Learning-generated images scored highest in quality. Additionally, we investigated an actual murine biopsy. Our study pioneers the application of AF spectra for tissue characterization and diagnostic potential of optically cleared unstained percutaneous biopsies, contributing to the clinical translation of LSFM.

Addressing critical gaps in protected area coverage for bird habitats in China.

Currently, protected areas cover approximately 14% of the Earth's land surface, yet 12.2% of the world's bird species remain unprotected by any designated areas and face significant threats. This study investigates the current status of bird conservation in China, aiming to evaluate the effectiveness of existing protected areas, analyze why certain bird species are not adequately protected, and propose strategies for optimizing protected area configurations. Utilizing citizen science data and the zonation optimization algorithm, we comprehensively assessed the conservation value of birds in China. We then employed anthropogenic stressor data to evaluate the conservation of threatened bird habitats through a binary conflict intensity model. Finally, we conducted a spatial overlap analysis to determine the coverage and effectiveness of Chinese nature reserves in regions with high conservation value and high conflict risk. Our findings indicate that only 10.0% of the highest conservation value bird habitats are covered by protected areas, and just 7.3% of these protected areas effectively safeguard these critical habitats. Additionally, only 5.9% of bird habitats impacted by human activity conflicts are within protected areas, and merely 22.0% of the total protected areas can effectively conserve high conflict risk habitats. Overall, China's current protected area system has substantial shortcomings in safeguarding bird habitats and requires further optimization and expansion to maximize conservation benefits.

Upright versus inverted catching and crating end-of-lay hens: a trade-off between animal welfare, ergonomic and financial concerns.

This study explores upright versus inverted catching and crating of spent laying hens. Both catching methods were compared using a cost-benefit analysis that focused on animal welfare, ergonomic, and financial considerations. Data were collected on seven commercial farms (one floor system and six aviary systems) during depopulation of approximately 3,000 hens per method per flock. Parameters such as wing flapping frequency, catcher bird interaction, incidence of catching damage and hens dead on arrival (DOA) were measured and compared between catching methods. Ergonomic evaluations were performed via catcher surveys and expert assessment of video recordings. The wing flapping frequency was lower (3.1 ± 0.6 vs. 4.0 ± 0.5, P < 0.001) and handling was gentler (1.9 ± 0.5 vs. 4.4 ± 0.5, P < 0.001), both on a 7-point Likert scale, for upright versus inverted catching. However, more person-hours per 1000 hens were required for upright than inverted catching (8.2 ± 3.2 h vs. 4.8 ± 2.0 h, P = 0.011), with only wing bruises being significantly less common for upright than inverted catching (1.1 ± 0.6 % vs. 1.7 ± 0.7%, P = 0.04). Upright catching was 1.8 times more expensive than inverted catching; compensation for this cost would require a premium price of approximately €0.0005 extra per egg. Ergonomically, both catching methods were considered demanding, although catchers (n = 29) preferred inverted catching. In conclusion, this study showed animal welfare benefits of upright vs. inverted catching. Industry adoption of upright catching will depend on compensation of the additional labor costs, adjustments to labor conditions and shorter loading times.

The Benefit of Hearing Aids as Measured by Listening Accuracy, Subjective Listening Effort, and Functional Near Infrared Spectroscopy.

There is broad consensus that listening effort is an important outcome for measuring hearing performance. However, there remains debate on the best ways to measure listening effort. This study sought to measure neural correlates of listening effort using functional near-infrared spectroscopy (fNIRS) in experienced adult hearing aid users. The study evaluated impacts of amplification and signal-to-noise ratio (SNR) on cerebral blood oxygenation, with the expectation that easier listening conditions would be associated with less oxygenation in the prefrontal cortex. Thirty experienced adult hearing aid users repeated sentence-final words from low-context Revised Speech Perception in Noise Test sentences. Participants repeated words at a hard SNR (individual SNR-50) or easy SNR (individual SNR-50 + 10 dB), while wearing hearing aids fit to prescriptive targets or without wearing hearing aids. In addition to assessing listening accuracy and subjective listening effort, prefrontal blood oxygenation was measured using fNIRS. As expected, easier listening conditions (i.e., easy SNR, with hearing aids) led to better listening accuracy, lower subjective listening effort, and lower oxygenation across the entire prefrontal cortex compared to harder listening conditions. Listening accuracy and subjective listening effort were also significant predictors of oxygenation.