Two common issues in synchronized multimodal recordings with EEG: Jitter and latency.

Multimodal recording using electroencephalogram (EEG) and other biological signals (e.g., muscle activities, eye movement, pupil diameters, or body kinematics data) is ubiquitous in human neuroscience research. However, the precise time alignment of multiple data from heterogeneous sources (i.e., devices) is often arduous due to variable recording parameters of commercially available research devices and complex experimental setups. In this review, we introduced the versatility of a Lab Streaming Layer (LSL)-based application that can overcome two common issues in measuring multimodal data: jitter and latency. We discussed the issues of jitter and latency in multimodal recordings and the benefits of time-synchronization when recording with multiple devices. In addition, a computer simulation was performed to highlight how the millisecond-order jitter readily affects the signal-to-noise ratio of the electrophysiological outcome. Together, we argue that the LSL-based system can be used for research requiring precise time-alignment of datasets. Studies that detect stimulus-induced transient neural responses or test hypotheses regarding temporal relationships of different functional aspects with multimodal data would benefit most from LSL-based systems.

Between-Tactor Display Using Dynamic Tactile Stimuli for Directional Cueing in Vibrating Environments.

Torso-worn vibrotactile devices have been used in many studies on directional cueing and navigation in environments where visual feedback is limited. These devices aim to indicate directions with high resolution while using the smallest possible number of vibration motors (tactors). Resolution can be increased using between-tactor displays, but their performance in vibrating environments (e.g., a helicopter) are unknown. This study proposes a between-tactor display using dynamic stimuli and verifies its effectiveness when the user sits in a vibrating chair. We developed a waist belt device that displays 12 directions using 6 tactors. Static stimuli display virtual (between-tactor) locations by constantly vibrating two adjacent tactors equally, whereas dynamic stimuli move the virtual vibration position back and forth between tactors. We performed two studies in which participants felt tactile stimuli and used a joystick to move a cursor on a screen to a target in the perceived direction. Direction recognition accuracy and task completion time were measured under combined conditions of two belt orientations (tactor alignments), with and without chair vibration, and with and without audio white noise to mask tactor sound. In all conditions, dynamic stimuli increased recognition accuracy while maintaining task completion time compared to static stimuli.

Compensatory gait mechanics in person with multiple toe amputation: A single case report.

This case highlights the biomechanical influence of toe amputation on contralateral limb force elevation, possibly through reduced ipsilateral plantar flexor torque production. These findings provide insight into toe amputation-related compensatory gait mechanics with greater inter-limb asymmetry, which may increase the risk of musculoskeletal comorbidities, including osteoarthritis in contralateral limb.

Antagonistic interactions between odorants alter human odor perception.

The olfactory system uses hundreds of odorant receptors (ORs), the largest group of the G-protein-coupled receptor (GPCR) superfamily, to detect a vast array of odorants. Each OR is activated by specific odorous ligands, and like other GPCRs, antagonism can block activation of ORs. Recent studies suggest that odorant antagonisms in mixtures influence olfactory neuron activities, but it is unclear how this affects perception of odor mixtures. In this study, we identified a set of human ORs activated by methanethiol and hydrogen sulfide, two potent volatile sulfur malodors, through large-scale heterologous expression. Screening odorants that block OR activation in heterologous cells identified a set of antagonists, including ß-ionone. Sensory evaluation in humans revealed that ß-ionone reduced the odor intensity and unpleasantness of methanethiol. Additionally, suppression was not observed when methanethiol and ß-ionone were introduced simultaneously to different nostrils. Our study supports the hypothesis that odor sensation is altered through antagonistic interactions at the OR level.

Hemoglobin in the blood acts as a chemosensory signal via the mouse vomeronasal system.

The vomeronasal system plays an essential role in sensing various environmental chemical cues. Here we show that mice exposed to blood and, consequently, hemoglobin results in the activation of vomeronasal sensory neurons expressing a specific vomeronasal G protein-coupled receptor, Vmn2r88, which is mediated by the interaction site, Gly17, on hemoglobin. The hemoglobin signal reaches the medial amygdala (MeA) in both male and female mice. However, it activates the dorsal part of ventromedial hypothalamus (VMHd) only in lactating female mice. As a result, in lactating mothers, hemoglobin enhances digging and rearing behavior. Manipulation of steroidogenic factor 1 (SF1)-expressing neurons in the VMHd is sufficient to induce the hemoglobin-mediated behaviors. Our results suggest that the oxygen-carrier hemoglobin plays a role as a chemosensory signal, eliciting behavioral responses in mice in a state-dependent fashion.

Gait analysis of patients with distal radius fracture by using a novel laser Timed Up-and-Go system.

BACKGROUND: Postmenopausal women are at risk of fall and fracture with the physical decline. Distal radius fracture (DRF) is considered as the primary fragility fracture, and women with this fracture showed poor results in the usual Timed Up-and-Go (TUG) test, indicating a decline in balance and physical ability. The detailed physical characteristics of female DRF patients have not been extensively examined. RESEARCH QUESTION: Is the novel laser TUG system able to detect and analyze the detailed gait characteristics in patients with DRF whose physical ability has tended to decline? METHODS: In this cross-sectional case control study, the gait characteristics of 32 female patients　with DRF who had undergone surgery were evaluated at 2 weeks postoperatively with a　laser TUG system to analyze the detailed leg motion during normal TUG test.　Forty-three age- and sex-matched non-fractured women were evaluated by the laser TUG system as controls. Lifestyle and present illness were corrected at the time of TUG measurement. Detailed data during laser TUG in both groups were compared statistically, and odds ratio and thread shod of the fracture was elucidated through a　logistic regression analysis. RESULTS: DRF patients showed slower speed and had to do more steps to complete the TUG test. Furthermore, asymmetric trajectory and significantly further distance from the marker were observed. Thirteen steps to complete the TUG test was the thread shod of DRF. SIGNIFICANCE: Detailed gait characteristics of patients with DRF were detected by the laser TUG system. The gait decline and abnormality could be one of the reasons of consecutive fragility fracture. To prevent secondary fragility fractures, this system can be useful for screening.

Transcutaneous Electrical Nerve Stimulation Improves Stair Climbing Capacity in People with Knee Osteoarthritis.

This study aimed to examine the effect of transcutaneous electrical nerve stimulation (TENS) on stair climbing capacity in individuals with pre-radiographic to mild knee osteoarthritis (OA). This is a secondary analysis of data from a single, participant-blinded, randomized controlled trial with a pre-post design. Participants with pre-radiographic to mild knee OA (mean age, 59.1 years; 72.9% women) were randomly assigned into two groups, a TENS (n = 30) and a sham-TENS groups (n = 29). TENS or sham-TENS treatments were applied to all participants by using the prototype TENS device with pre-specified parameters. The primary outcome measures included valid and reliable functional measures for stair climbing (stair-climb test [SCT]), visual analog scale for knee pain during the SCT, and quadriceps muscle strength. TENS improved SCT time by 0.41 s (95% confidence interval [CI]: 0.07, 0.75). The time reduction in the transition phase explains the TENS therapeutic effect. Post-hoc correlation analyses revealed a non-significant but positive relationship between the pain relief effect and improved 11-step SCT time in the TENS group but not in the sham-TENS group. These results indicate that the TENS intervention may be an option for reducing the burden of early-stage knee OA.

Hip abductor muscle weakness and slowed turning motion in people with knee osteoarthritis.

Laser range sensor-based timed up and go (laser-TUG) test can evaluate performance in TUG subtasks (sit-to-walk [STW], walking a short distance, and turning). This study aimed to test the hypothesis that weaker hip abductor muscle strength is more significantly associated with slowed turning speed than with the other TUG subtasks (STW and straight walking) after controlling for quadriceps muscle strength in patients with knee osteoarthritis (OA). Community-dwelling participants with knee OA (Kellgren and Lawrence [K&L] grade ≥ 1; mean age, 68.6 years; 70.3% women) underwent laser-TUG. Spatiotemporal gait parameters in TUG and the TUG subtasks were evaluated as outcome measures. The isometric muscle strength of the hip abductor and quadriceps was measured using a hand-held dynamometer. Multiple linear regression analysis was performed to examine the relationship between muscle strength as an independent variable and spatiotemporal parameters as dependent variables. The relative importance of hip abductor muscle strength was determined using the percentages of unique variance. Participants with weaker hip abductor muscle strength demonstrated 0.094 m/s slower turning speed after adjustment for covariates including quadriceps muscle strength. The unique variance explained by hip abductor muscle strength in turning speed was 2.1%. However, no significant relationships were confirmed between weak hip abductor muscle strength and the time to perform TUG and the straight walking (forward and return) phase. These findings indicate that turning motion may be more sensitive to aggravated hip abductor muscle weakness and may show better response to hip muscle strengthening exercises. Longitudinal studies are warranted to elucidate this issue.

Estimation of Vertical Ground Reaction Force Using Low-Cost Insole With Force Plate-Free Learning From Single Leg Stance and Walking.

For the evaluation of pathological gait, a machine learning-based estimation of the vertical ground reaction force (vGRF) using a low-cost insole is proposed as an alternative to costly force plates. However, learning a model for estimation still relies on the use of force plates, which is not accessible in small clinics and individuals. Therefore, this paper presents a force plate-free learning from a single leg stance (SLS) and natural walking measured only by the insoles. This method used a linear least squares regression that fits insole measurements during SLS to body weight in order to learn a model to estimate vGRF during walking. Constraints were added to the regression so that vGRF estimates during walking were of proper magnitude, and the constraint bounds were newly defined as a linear function of stance duration. Moreover, a lower bound for the estimated vGRF in mid-stance was added to the constraints to enhance estimation accuracy. The vGRF estimated by the proposed method was compared with force platforms for 4 healthy young adults and 13 elderly adults including patients with mild osteoarthritis, knee pain, and valgus hallux. Through the experiments, the proposed learning method had a normalized root mean squared error under 10% for healthy young and elderly adults with stance durations within a certain range (600-800 ms). From these results, the validity of the proposed learning method was verified for various users requiring assessment in the field of medicine and healthcare.

Stair climbing ability in patients with early knee osteoarthritis: Defining the clinical hallmarks of early disease.

BACKGROUND: A growing clinical interest has been shown towards identifying knee osteoarthritis (OA) patients at earlier stages. The early detection of knee OA may allow for more effective interventions. RESEARCH QUESTION: The aim of this study was to determine the discriminative ability of a stair-climb test (SCT) in identifying patients with early knee OA, and to determine if descending stair time during the SCT is better than ascending stair time for the identification of these patients. METHODS: This study was a secondary, cross-sectional analysis of baseline data from a randomized controlled trial. Adults with moderate to severe knee pain were enrolled (n = 57; mean age 58.9 years; 71.9% women). Each participant performed an 11-step SCT (11-SCT) while wearing shoes with a pressure sensor insole. A receiver operating characteristic analysis was used to examine the discriminative power of 11-SCT for identifying early knee OA (Kellgren and Lawrence grade 1). The discriminative power was also compared between the ascending and descending 11-SCT time as evaluated by the pressure sensor. RESULTS: The 11-SCT time in patients with early knee OA was 0.55 s longer than that in those with symptomatic non-radiographic OA. A one-second increase in the 11-SCT time was significantly associated with 1.9-fold increased odds of early knee OA being present. The 11-SCT value with the best balance of sensitivity and specificity for identifying early knee OA was 8.33 s (area under the curve: 0.711). The descending time was not significantly better than the ascending time for identifying early knee OA. SIGNIFICANCE: This study determined the time values of an 11-SCT that may be useful for identifying early knee OA patients. These preliminary findings may serve as the foundation for future studies investigating the clinical hallmarks associated with early knee OA.

Insole-Based Estimation of Vertical Ground Reaction Force Using One-Step Learning With Probabilistic Regression and Data Augmentation.

An insole-based estimation of the vertical ground reaction force (vGRF) is proposed as an alternative to costly force plates for the evaluation of pathological gait. However, machine learning techniques for estimation still rely on the use of force plates. Moreover, measuring plural walking steps in order to prevent overfitting induces fall risks and physically taxes the patients. Therefore, this paper presents an accessible and efficient learning scheme for the insole-based estimation of vGRF. In this system, we employ a low-cost scale as an alternative to force plates. Then, we use Gaussian process regression (GPR) to learn a model in order to estimate vGRF without overfitting of small-sized data sets corrupted by measurement errors and noise of the devices. In addition, we propose a "one-step learning" scheme based on a probabilistic data augmentation. This approach augments actual measurements of a minimum (just one) walking step to a virtual data set for plural steps by considering their typical variability between steps. In experiments, the GPR models learned from two walking steps estimated vGRF with mean errors of 8% or under for entire/local magnitudes. Moreover, the learning from one step with probabilistic augmentation enhanced the estimation accuracy.

Effects of interaction between varus thrust and ambulatory physical activity on knee pain in individuals with knee osteoarthritis: an exploratory study with 12-month follow-up.

INTRODUCTION: This study aimed to examine the interaction effect between ambulatory physical activity (PA) and varus thrust on knee pain in individuals with knee osteoarthritis (OA). METHOD: Subjects (n = 207; mean age: 73.1 years, 71.5% women) in orthopedic clinics with diagnosed knee OA (Kellgren/Lawrence grade ≥ 1) were enrolled in this 12-month observational cohort study. Participants underwent gait observation for varus thrust assessment and pedometer-based ambulatory PA measurements at baseline and 12-month follow-up. Knee pain intensity was assessed using the Japanese Knee Osteoarthritis Measure pain subscale as a primary outcome measure. Multiple linear regression analyses were performed to evaluate ambulatory PA-thrust interaction on knee pain intensity. RESULTS: Ninety-two subjects (mean age, 73.4 years; 68.5% women) completed the 12-month follow-up assessment. Baseline ambulatory PA-thrust interaction was significant (P = 0.017) in the cross-sectional analysis, adjusting for covariates, which yielded R2 = 0.310. Subgroup analysis showed that varus thrust was significantly associated with worse knee pain in subjects walking ≥ 5000 steps/day adjusting for covariates (beta: 7.94; 95% CI: 3.82, 12.1; P < 0.001) with a higher predictive ability (R2 = 0.664). In contrast, ambulatory PA-thrust interaction in the longitudinal analysis showed no significant association with knee pain changes. CONCLUSIONS: Ambulatory PA interacted with varus thrust in the association with knee pain, as coexisting high ambulatory PA and varus thrust had the strongest association with higher knee pain. Maximal pain relief effects might be achieved when both ambulatory PA and varus thrust are treated simultaneously, rather than treating each separately.

Concurrent validity and measurement error of stair climb test in people with pre-radiographic to mild knee osteoarthritis.

BACKGROUND: Stair climbing is the task first affected in patients with knee osteoarthritis (OA); therefore, the precise measurement of time required to climb stairs is important to identify mobility limitations, particularly in the early phase of knee OA. RESEARCH QUESTION: This study aimed to examine the test-retest reliability, measurement error, and concurrent validity of the stopwatch-based stair-climb test (SCT) in adults with pre-radiographic to mild knee OA. METHODS: Fifty-nine participants (mean age, 59.1 [range, 50-69] years; 72.9% female) with Kellgren and Lawrence grade ≤2 disease underwent an 11-step SCT (11-SCT) in accordance with the Osteoarthritis Research Society International recommended method while wearing pressure sensor-mounted standard shoes that is used as a gold standard procedure. Test-retest reliability, measurement errors, and the concurrent validity of the stopwatch-based 11-SCT were evaluated. RESULTS: The test-retest reliability of the stopwatch-based 11-SCT was excellent (intra-class correlation coefficient1,1 [ICC1,1], 0.952; 95% confidence interval [CI], 0.560 to 0.985; p < 0.001) and the minimal detectable change95 was 0.102 s. Concurrent validity was excellent (ICC2,1: 0.957; 95% CI: 0.661 to 0.986; p < 0.001). SIGNIFICANCE: The stopwatch-based 11-SCT had high test-retest reliability and high concurrent validity, which justify its clinical use for identifying mobility limitations in individuals with pre-radiographic to mild knee OA. A difference of 0.2 s in the stopwatch-based 11-SCT time would be considered a true difference beyond a 95% measurement error.

Sexual rejection via a vomeronasal receptor-triggered limbic circuit.

Mating drive is balanced by a need to safeguard resources for offspring, yet the neural basis for negative regulation of mating remains poorly understood. In rodents, pheromones critically regulate sexual behavior. Here, we observe suppression of adult female sexual behavior in mice by exocrine gland-secreting peptide 22 (ESP22), a lacrimal protein from juvenile mice. ESP22 activates a dedicated vomeronasal receptor, V2Rp4, and V2Rp4 knockout eliminates ESP22 effects on sexual behavior. Genetic tracing of ESP22-responsive neural circuits reveals a critical limbic system connection that inhibits reproductive behavior. Furthermore, V2Rp4 counteracts a highly related vomeronasal receptor, V2Rp5, that detects the male sex pheromone ESP1. Interestingly, V2Rp4 and V2Rp5 are encoded by adjacent genes, yet couple to distinct circuits and mediate opposing effects on female sexual behavior. Collectively, our study reveals molecular and neural mechanisms underlying pheromone-mediated sexual rejection, and more generally, how inputs are routed through olfactory circuits to evoke specific behaviors.

Identification of an Intra- and Inter-specific Tear Protein Signal in Rodents.

Rodents use the vomeronasal olfactory system to acquire both inter- and intra-specific information from the external environment and take appropriate actions. For example, urinary proteins from predator species elicit avoidance in mice, while those from male mice attract female mice. In addition to urinary proteins, recent studies have highlighted the importance of lacrimal proteins for intra-specific communications in mice. However, whether the tear fluid of other species also mediates social signals remains unknown. Here, we show that a lacrimal protein in rats (predators of mice), called cystatin-related protein 1 (ratCRP1), activates the vomeronasal system of mice. This protein is specifically produced by adult male rats in a steroid hormone-dependent manner, activates the vomeronasal system of female rats, and enhances stopping behavior. When detected by mice, ratCRP1 activates the medial hypothalamic defensive circuit, resulting in decreased locomotion coupled with lowered body temperature and heart rate. Notably, ratCRP1 is recognized by multiple murine type 2 vomeronasal receptors, including Vmn2r28. CRISPR/Cas9-mediated deletion of vmn2r28 impaired both ratCRP1-induced neural activation of the hypothalamic center and decrease of locomotor activity in mice. Taken together, these data reveal the neural and molecular basis by which a tear fluid compound in rats affects the behavior of mice. Furthermore, our study reveals a case in which a single compound that mediates an intra-specific signal in a predator species also functions as an inter-specific signal in the prey species.

Proton conduction in alkali metal ion-exchanged porous ionic crystals.

Proton conduction in alkali metal ion-exchanged porous ionic crystals A2[Cr3O(OOCH)6(etpy)3]2[α-SiW12O40]·nH2O [I-A+] (A = Li, Na, K, Cs, etpy = 4-ethylpyridine) is investigated. Single crystal and powder X-ray diffraction measurements show that I-A+ possesses analogous one-dimensional channels where alkali metal ions (A+) and water of crystallization exist. Impedance spectroscopy and water diffusion measurements of I-A+ show that proton conductivities are low (10-7-10-6 S cm-1) under low relative humidity (RH), and protons mostly migrate as H3O+ with H2O as vehicles (vehicle mechanism). The proton conductivity of I-A+ increases with the increase in RH and is largely dependent on the types of alkali metal ions. I-Li+ shows a high proton conductivity of 1.9 × 10-3 S cm-1 (323 K) and a low activation energy of 0.23 eV under RH 95%. Under high RH, alkali metal ions with high ionic potentials (e.g., Li+) form a dense and extensive hydrogen-bonding network of water molecules with mobile protons at the periphery, which leads to high proton conductivities and low activation energies via rearrangement of the hydrogen-bonding network (Grotthuss mechanism).

[Factors influencing intraocular pressure elevation on the first postoperative day following small-incision cataract surgery--the effect of apraclonidine].

PURPOSE: To investigate the effects of apraclonidine on intraocular pressure elevation after cataract surgery and the factors associated with elevated intraocular pressure. METHODS: A group of patients (apraclonidine group) was administered a drop of apraclonidine before and one drop after surgery, and the difference between the intraocular pressure in the apraclonidine group and the non-use group was investigated postoperatively. On the first postoperative day, multivariate analysis was performed using intraocular pressure as the objective value and other variable factors involved in the surgery as the explanatory variables. RESULTS: On the first postoperative day, the intraocular pressure in the apraclonidine group (520 eyes: 15.5 +/- 4.9 mmHg) was significantly lower than that in the non-use group (577 eyes: 18.7 +/- 7.2 mmHg) (p < 0.001). The significant variables included preoperative intraocular pressure, apraclonidine use, sex (men > women), poor mydriasis, acetylcholine use, pseudoexfoliation, and diabetes mellitus. CONCLUSIONS: Apraclonidine is useful in suppressing postoperative elevation of intraocular pressure.