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Perceptual learning is a multifaceted process, encompassing general learning, between-session forgetting or consolidation, and within-session fast relearning and deterioration. The learning curve constructed from threshold estimates in blocks or sessions, based on tens or hundreds of trials, may obscure component processes; high temporal resolution is necessary. We developed two nonparametric inference procedures: a Bayesian inference procedure (BIP) to estimate the posterior distribution of contrast threshold in each learning block for each learner independently and a hierarchical Bayesian model (HBM) that computes the joint posterior distribution of contrast threshold across all learning blocks at the population, subject, and test levels via the covariance of contrast thresholds across blocks. We applied the procedures to the data from two studies that investigated the interaction between feedback and training accuracy in Gabor orientation identification over 1920 trials across six sessions and estimated learning curve with block sizes L = 10, 20, 40, 80, 160, and 320 trials. The HBM generated significantly better fits to the data, smaller standard deviations, and more precise estimates, compared to the BIP across all block sizes. In addition, the HBM generated unbiased estimates, whereas the BIP only generated unbiased estimates with large block sizes but exhibited increased bias with small block sizes. With L = 10, 20, and 40, we were able to consistently identify general learning, between-session forgetting, and rapid relearning and adaptation within sessions. The nonparametric HBM provides a general framework for fine-grained assessment of the learning curve and enables identification of component processes in perceptual learning.

Objective Explore the therapeutic effect of Yangpafang on behavior and pain in subacute Parkinson's disease (PD) model mice and its possible mechanism. Methods Total 42 specific pathogen⁃free (SPF) C57BL/6J mice were randomly divided into control group, model group, Yangpafang low⁃ dose group [13.50 g/(kg·d)], medium ⁃dose group [40.50 g/(kg·d)] and high⁃dose group [121.50 g/(kg·d)], levodopa and benserazide group (7 mice in each group). The behavioral changes of mice were evaluated by Pole Climbing Test, Suspension Test and Field Test. The thermal nociceptive threshold and mechanical nociceptive threshold were measured by thermal pain response latency measuring instrument and electronic pressure pain measuring instrument. Immunohistochemical staining was used to detect the positive expression of tyrosine hydroxylase (TH) in substantia nigra and amygdala. Results There were significant differences in pole climbing time (F = 14.625, P = 0.000), suspension score (F = 24.493, P = 0.000), resting time of Field Test (F = 24.506, P = 0.000), thermal nociceptive threshold (F = 24.726, P = 0.000) and mechanical nociceptive threshold (F = 21.052, P = 0.000), TH positive expression in substantia nigra (F = 19.663, P = 0.000) and amygdala (F = 36.513, P = 0.000) among different treatment groups. Compared with the control group, the pole climbing time (P = 0.000) and resting time (P = 0.000) of the model group were prolonged, and the suspension score (P = 0.000), thermal nociceptive threshold (P = 0.000) and mechanical nociceptive threshold (P = 0.000), substantia nigra (P = 0.000) and amygdala (P = 0.000) TH positive expression decreased. Compared with the model group, the pole climbing time (P = 0.020, 0.000, 0.000, 0.000) and resting time (P = 0.000, 0.000, 0.000, 0.000) of Yangpafang low⁃dose group, medium⁃dose group, high ⁃ dose group and levodopa and benserazide group were shortened, but still longer than those of the control group (P < 0.05, for all). The suspension score (P = 0.000, 0.000, 0.000, 0.000, 0.000), thermal nociceptive threshold (P = 0.008, 0.000, 0.000, 0.000) and mechanical nociceptive threshold (P = 0.003, 0.000, 0.000, 0.000), TH positive expression in substantia nigra (P = 0.031, 0.001, 0.000, 0.000) and amygdala (P = 0.007, 0.000, 0.000, 0.000) increased. The thermal nociceptive threshold in other 3 groups was still lower than that in the control group (P < 0.05, for all), except that the levodopa and benserazide group returned to the level of the control group (P = 0.063). Compared with the Yangpafang low⁃dose group, the pole climbing time (P = 0.009, 0.009, 0.006) and resting time (P = 0.024, 0.018, 0.001) in the Yangpafang medium ⁃ dose group, high ⁃ dose group and the levodopa and benserazide group were also shortened, but still longer than those in the control group (P < 0.05, for all). Suspension score (P = 0.015, 0.011, 0.002), thermal nociceptive threshold (P = 0.001, 0.001, 0.000) and mechanical nociceptive threshold (P = 0.035, 0.001, 0.001) also increased, TH positive expression was also increased in the substantia nigra (P = 0.043, 0.023, 0.001) and amygdala (P = 0.007, 0.005, 0.000). Except that the TH positive expression in the amygdala of the levodopa and benserazide group was higher than that of the Yangpafang medium⁃dose group (P = 0.009) and the high⁃dose group (P = 0.012), there was no significant difference in each index between the latter 3 groups (P > 0.05, for all). Conclusions Yangpafang can improve the behavior and pain of subacute PD model mice, which is related to the protection of amygdala and substantia nigra dopaminergic neurons.

Background: Acute low back pain has a high prevalence, and when persisting into chronicity, it results in enormous socio-economic consequences. Sensory preferences may be key factors in predicting central sensitization as the main mechanism of nociplastic pain and chronicity. Objectives: Build a model to predict central sensitization symptoms using sensory profiles based on the PROGRESS framework. Methods: A Prognostic Model Research study was carried out to predict central sensitization symptoms at 12 weeks, using baseline sensory profiles, based on 114 patients with acute low back pain. Independent variables were sensory profiles, state and trait anxiety, age, duration, pain severity, depressive symptoms, and pain catastrophizing. Results: This model, based on continuous data, significantly predicts central sensitization symptoms at 12 weeks. It contains two significantly contributing variables: sensory profile Sensory Sensitive (unstandardized B-value = 0.42; p = 0.01) and trait anxiety (unstandardized B-value = 0.53; p ≤ 0.001). The model has a predictive value of R2 = 0.38. Conclusions: This model significantly predicts central sensitization symptoms based on sensory profile Sensory Sensitive and trait anxiety. This model may be a useful tool to intervene in a bottom–up and top–down approaches to prevent chronicity in clinical practice, including individual sensory preferences and behavioral responses to sensory stimulation in rehabilitation strategies. [ABSTRACT FROM AUTHOR]

Patients with persistent postural-perceptual dizziness (PPPD) perceive postural instability larger than the observed sway. It is unknown whether the concept of postural misperception prevails during vestibular stimulation and whether it may account for the unsteadiness patients complain during body movements. We tested the hypothesis of an abnormal sensory-perceptual scaling mechanism in PPPD by recording objective, perceived, and the reproduced postural sway under various standing conditions, modulating visual and proprioceptive input, by binaural galvanic vestibular stimulation (GVS). We related postural sway speed to individual vestibular motion perceptional thresholds and disease-related PPPD questionnaires in 32 patients and 28 age-matched healthy control subjects (HC). All participants showed normal vestibular function tests on quantitative testing at the time of enrollment. The perception threshold of GVS was lower in patients. Compared to HC, patients showed and perceived larger sway on the firm platform. With GVS, posturo-perceptual ratios did not show group differences. The ratio of reproduced to real postural sway showed no group differences indicating normal postural sway perception during vestibular stimulation. Noticeably, only in patients, reproduced postural instability became larger with lower individual thresholds of vestibular motion detection. We conclude that posturo-perceptual (metacognitive) scaling of postural control seems to be largely preserved in PPPD during GVS. Vestibular stimulation does not destabilize patients more than HC, even in challenging postural conditions. Low individual thresholds of vestibular motion perception seem to facilitate instability and postural misperception on solid grounds. This conclusion is important for an effective physical therapy with vestibular exercises in PPPD. [ABSTRACT FROM AUTHOR]

Background: Psychosocial function of Chinese temporomandibular disorders (TMD) pain patients and the correlation with somatosensory function has not been sufficiently studied. Objective: The study aims at assessing the psychosocial function of Chinese TMD pain patients by visualisation method and evaluating the correlations with somatosensory function quantitatively. Methods: The Symptom Checklist 90 (SCL‐90) questionnaire and standardised quantitative sensory testing (QST) were administered to 70 Chinese TMD pain patients and age‐ and gender‐matched healthy controls (HCs). Of these, 40 TMD arthralgia patients received QST before and after medication. Psychosocial and somatosensory parameters were transformed into standardised scores. Differences within groups were assessed through t tests. Correlations between psychosocial and somatosensory profiles were explored through correlation analyses with Bonferroni correction for multiple comparisons. Results: 100% of the Chinese TMD pain patients exhibited psychosocial distress in contrast to HCs. Anger and hostility showed negative correlation with the thermal nonnociceptive parameter (thermal sensory limen, p =.002) and nociceptive parameters (cold pain threshold and pain pressure threshold, p<.001). Correlation analysis indicated that cold detection threshold was negatively correlated with somatization and mechanical pain sensitivity had a negative correlation with anger and hostility through medical treatment (p <.001). Conclusions: Visual psychosocial profiles provided an easy overview of psychosocial function in Chinese TMD pain patients. Anger and hostility was associated with increased thermal nonnociceptive and nociceptive sensitivity to stimuli. Psychosocial distress might be negatively associated with TMD treatment response which indicated a possible need for psychological intervention during treatment. [ABSTRACT FROM AUTHOR]

Legislation on the quality of water intended for human consumption requires routine taste and odour controls. So far, no procedures or technical documents exist which can be used as a reference in the training of sensory assessors for tap water. This work presents the procedure for the development of a trained panel and it describes all the steps carried out: the recruitment, pre-selection, selection and training phase considering the different odours and flavours that tap water may contain. In order to analyse the performance of the assessors in the training phase, 6 parameters and 15 criteria are proposed. The assessors who fulfilled the criteria, will integrate a qualified panel to carry out tap water sensory controls. This process has shown to be suitable and strict enough to train assessors on tap water evaluation, and can therefore function as a reference for other laboratories on which to base their training and qualification of assessor panels on tap water quality control.

That binocular viewing confers an advantage over monocular viewing for detecting isolated low luminance or low contrast objects, has been known for well over a century; however, the processes involved in combining the images from the two eyes are still not fully understood. Importantly, in natural vision, objects are rarely isolated but appear in context. It is well known that nearby contours can either facilitate or suppress detection, depending on their distance from the target and the global configuration. Here we report that at close distances collinear (but not orthogonal) flanking contours suppress detection more under binocular compared to monocular viewing, thus completely abolishing the binocular advantage, both at threshold and suprathreshold levels. In contrast, more distant flankers facilitate both monocular and binocular detection, preserving a binocular advantage up to about four times the detection threshold. Our results for monocular and binocular viewing, for threshold contrast discrimination without nearby flankers, can be explained by a gain control model with uncertainty and internal multiplicative noise adding additional constraints on detection. However, in context with nearby flankers, both contrast detection threshold and suprathreshold contrast appearance matching require the addition of both target-to-target and flank-to-target interactions occurring before the site of binocular combination. To test an alternative model, in which the interactions occur after the site of binocular combination, we performed a dichoptic contrast matching experiment, with the target presented to one eye, and the flanks to the other eye. The two models make very different predictions for abutting flanks under dichoptic conditions. Interactions after the combination site predict that the perceived contrast of the flanked target will be strongly suppressed, while interactions before the site predict the perceived contrast will be more or less veridical. The data are consistent with the latter model, strongly suggesting that the interactions take place before the site of binocular combination.

Background: Age-, gender- and body site-specific values of thermal Quantitative Sensory Testing (QST) measures have not yet been reported using the novel and cheap device 'Q-sense'. Here, we aimed to assess normative values of Q-sense-derived parameters in a representative Italian population. Methods: QST parameters were measured in 84 healthy participants (42 males; aged 20–76 years) equally distributed into three age groups (18–39, 40–59 and 60–80 years). We explored the Warm and the Cold Detection Thresholds (WDT and CDT, respectively) with the method of limits (MLI) and the method of levels (MLE), and the Heat Pain Threshold (HPT) with the MLI. We tested the trigeminal supraorbital region, the hand thenar, and the foot dorsum on the right body side. Results: We calculated non-parametric reference limits (2.5–97.5th) according to age, gender and tested site. All QST measures were affected by age, gender and tested site. In the extra-trigeminal body sites, females showed lower WDT and higher CDT, while males had higher HPT. Worse sensory discriminative abilities and increased HPT values were found in people aged over 40 on the foot. Age-related differences were more evident with the reaction time–dependent MLI vs. MLE paradigm. Conclusions: Demographic characteristics must be considered when QST is used in the clinical setting. The definition of reference limits for sensory testing with the Q-sense herein provided can pave the way towards a more widespread use of thermal QST for diagnosing small fiber neuropathy and for identifying patients' profiles in different chronic pain syndromes. [ABSTRACT FROM AUTHOR]

Human adults with normal vision are capable of improving performance on visual tasks through repeated practice. Previous work has shown that enhancing synaptic levels of acetylcholine (ACh) in healthy human adults with donepezil (trade name: Aricept) can increase the magnitude and specificity of perceptual learning (PL) for motion direction discrimination in the perifovea. In the current study, we ask whether increasing the synaptic levels of ACh in healthy human adults with donepezil boosts learning of low-contrast isolated letter identification and high-contrast flanked letter identification in normal peripheral vision. Two groups of observers performed sequential training over multiple days while ingesting donepezil. One group trained on isolated low-contrast letters in Phase 1 and crowded high-contrast letters in Phase 2, and the other group performed the reverse sequence, thereby enabling us to differentiate possible effects of drug and training order on PL of letter identification. All testing and training were performed monocularly in peripheral vision, at an eccentricity of 10 degrees along the lower vertical meridian. Our experimental design allowed us to evaluate the effects of sequential training and to ask whether increasing cholinergic signaling boosted learning and/or transfer of low-contrast isolated letter identification and high-contrast flanked letter identification in normal peripheral vision. We found that both groups improved on each of the two tasks. However, our results revealed an effect of training task order on flanked letter identification: Observers who trained on isolated targets first showed rapid early improvement in flanked letter identification but little to no additional improvement after 30 training blocks, while observers who first trained with flanked letters improved gradually on flanked letter identification over the entire 100-block course of training. In addition, we found no effect of donepezil on PL of either isolated or flanked letter identification. In other words, donepezil neither boosted nor blocked learning to identify isolated low-contrast letters or learning to uncrowd in normal peripheral vision.

Hyper-reactivity to sensory input is a common and debilitating symptom in individuals with autism spectrum disorders (ASD), but the neural basis underlying sensory abnormality is not completely understood. Here we examined the neural representations of sensory perception in the neocortex of a Shank3B-/- mouse model of ASD. Male and female Shank3B-/- mice were more sensitive to relatively weak tactile stimulation in a vibrissa motion detection task. In vivo population calcium imaging in vibrissa primary somatosensory cortex (vS1) revealed increased spontaneous and stimulus-evoked firing in pyramidal neurons but reduced activity in interneurons. Preferential deletion of Shank3 in vS1 inhibitory interneurons led to pyramidal neuron hyperactivity and increased stimulus sensitivity in the vibrissa motion detection task. These findings provide evidence that cortical GABAergic interneuron dysfunction plays a key role in sensory hyper-reactivity in a Shank3 mouse model of ASD and identify a potential cellular target for exploring therapeutic interventions.

Objectives: Anorectal sensation is an essential component for maintaining normal defecation and continence. This study aimed to investigate changes in anorectal sensation with age and sex using the anorectal sensory threshold to electrical stimulation in a large population with a broad age spectrum. Methods: This study enrolled consecutive adult patients (20-89 years old) who underwent anorectal physiology tests to screen for functional or organic anorectal disease. Anorectal sensitivity was measured using an endoanal electrode with a 45-mm long bipolar needle. A constant electrical current was delivered to the lower end of the rectum and the anal canal. The minimum current in milliamperes at which the initial sensation was felt was defined as the sensory threshold. Results: Overall, 888 patients were included in this study. The most frequent comorbidities were constipation and hemorrhoids. The median sensory threshold for all patients was 0.5 (interquartile range, 0.2-1.5) mA, and the overall sensory threshold was significantly higher in men than in women. The 95% confidence interval of the sensory threshold for men and women were 0.1-6.8 and 0.1-5.1 mA, respectively. The sensory threshold increased significantly with age in both sexes (men, r = 0.384; women, r = 0.410). There was no sex difference in the sensory threshold between ages 20 and 40 years; however, between ages 50 and 70 years, men had a higher sensory threshold than women. Conclusions: The anorectal sensory threshold to electrical stimulation increased with age, and the influence of aging was more significant in men than in women.

PurposeTo review central structure-function (SF) relationships in glaucoma; to compare contributions of within-session and between-session variability to total variability of macular optical coherence tomography (OCT) thickness measurements; and to test the hypothesis that longitudinal within-eye variability of central SF relationships is smaller than between-individual variability.MethodsWe reviewed the pertinent literature on central SF relationships in glaucoma. Thirty-eight eyes (20 normal or glaucoma subjects) had ×3 macular images per session over 3 sessions, and superpixels thickness measurements for ganglion cell layer (GCL), ganglion cell/inner plexiform layer (GCIPL), ganglion cell complex (GCC), and full macular thickness (FMT) were exported. Linear mixed models were used for estimating contributions of between- and within-session variability to total thickness variability. One hundred twenty eyes with ≥3 10° visual fields (VFs)/OCT images were enrolled for the longitudinal study. We investigated within-eye longitudinal SF relationships (GCIPL thickness vs VF total deviations) with a change-point regression model and compared within-eye to between-individual variabilities with components-of-variance models.ResultsIn the cross-sectional study, the between-session component contributed 8%, 11%, 11%, and 36% of total variability for GCL, GCIPL, GCC, and FMT, respectively. In the longitudinal study, between-individual variability explained 78%, 77%, and 67% of total SF variability at 3.4°, 5.6°, and 6.8° eccentricities, respectively (P < .05). SF relationships remained stable over time within individual eyes.ConclusionsWithin-session variability accounts for most of macular thickness variability over time. Longitudinal within-eye SF variability is smaller than between-individual variability. Study of within-eye SF relationships could help clinicians better understand SF linking in glaucoma and help refine progression algorithms. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

The staircase method has been widely used in measuring perceptual learning. Recently, Zhao, Lesmes, and Lu (2017, 2019) developed the quick Change Detection (qCD) method and applied it to measure the trial-by-trial time course of dark adaptation. In the current study, we conducted two simulations to evaluate the performance of the 3-down/1-up staircase and qCD methods in measuring perceptual learning in a two-alternative forced-choice task. In Study 1, three observers with different time constants (40, 80, and 160 trials) of an exponential learning curve were simulated. Each simulated observer completed staircases with six step sizes (1%, 5%, 10%, 20%, 30%, and 60%) and a qCD procedure, each starting at five levels (+50%, +25%, 0, -25%, and -50% different from the true threshold in the first trial). We found the following results: Staircases with 1% and 5% step sizes failed to generate more than five reversals half of the time; and the bias and standard deviations of thresholds estimated from the post hoc segment-by-segment qCD analysis were much smaller than those from the staircase method with the other four step sizes. In Study 2, we simulated thresholds in the transfer phases with the same time constants and 50% transfer for each observer in Study 1. We found that the estimated transfer indexes from qCD showed smaller biases and standard deviations than those from the staircase method. In addition, rescoring the simulated data from the staircase method using the Bayesian estimation component of the qCD method resulted in much-improved estimates. We conclude that the qCD method characterizes the time course of perceptual learning and transfer more accurately, precisely, and efficiently than the staircase method, even with the optimal 10% step size.

Accurate knowledge of species colour discrimination is fundamental to explain colour based behaviours and the evolution of colour patterns. We tested how the receptor noise limited model, widely used in behavioural ecology, matched actual colour discrimination thresholds obtained using behavioural tests. Guppies (Poecilia reticulata) were first trained to push a target coloured disk placed among eight grey disks of various luminances on a grey plate. Guppies were then tested to find target disks, which varied in colour contrast from the plate. The target disks followed a gradient going from high contrast to inconspicuous against the grey background. We plotted the percentage of correct choices of each colour in the gradient against the model prediction and determined the discrimination thresholds using the inflection point of the fitted sigmoid curve. We performed the experiment on six colour gradients: red, orange, yellow, green, blue and purple. Four colour gradients: red, orange, green and blue, showed a discrimination threshold that matched the model predictions. However, deviations of the model for the yellow and purple gradients suggest that ecological relevance of some colours could affect decision-making in behavioural tests and that we can no longer assume that the rules for colour discrimination are independent of colours.

Colour vision mediates ecologically relevant tasks for many animals, such as mate choice, foraging and predator avoidance. However, our understanding of animal colour perception is largely derived from human psychophysics, and behavioural tests of non-human animals are required to understand how colour signals are perceived. Here, we introduce a novel test of colour vision in animals inspired by the Ishihara colour charts, which are widely used to identify human colour deficiencies. In our method, distractor dots have a fixed chromaticity (hue and saturation) but vary in luminance. Animals can be trained to find single target dots that differ from distractor dots in chromaticity. We provide MATLAB code for creating these stimuli, which can be modified for use with different animals. We demonstrate the success of this method with triggerfish, Rhinecanthus aculeatus, which quickly learnt to select target dots that differed from distractor dots, and highlight behavioural parameters that can be measured, including success of finding the target dot, time to detection and error rate. We calculated discrimination thresholds by testing whether target colours that were of increasing colour distances (ΔS) from distractor dots could be detected, and calculated discrimination thresholds in different directions of colour space. At least for some colours, thresholds indicated better discrimination than expected from the receptor noise limited (RNL) model assuming 5% Weber fraction for the long-wavelength cone. This methodology could be used with other animals to address questions such as luminance thresholds, sensory bias, effects of sensory noise, colour categorization and saliency.

ObjectivesNumbness associated with neuropathic pain suggests the loss of function in myelinated, large diameter sensory neurons. The purpose of this study was to examine the relationships between pain severity and subjective (ie, severity of numbness) and objective (ie, loss of light touch sensations, vibration thresholds) measures of loss of large fiber function in adult survivors with chemotherapy-induced peripheral neuropathy (CIPN, n=426) and breast cancer patients with persistent postsurgical pain (n=80).Material and methodsFor both samples, average pain and numbness were evaluated using a 0 to 10 numeric rating scale. Loss of light touch sensations in the hands and feet of patients with CIPN and in the upper arm of patients at 5 and 6 months following breast cancer surgery were assessed using Semmes Weinstein monofilaments. Loss of vibration in the hands and feet of patients with CIPN was assessed using a biothesiometer. Pearson Product Moment correlation coefficients were calculated between average pain and the number or percentage of sites with loss of light touch sensations, mean vibration thresholds, and the severity of numbness.ResultsFor both pain conditions, average pain scores were significantly correlated with objective measures of large fiber function (r=0.12 to 0.34; all P

PurposeTo compare the performance of the pattern standard deviation (PSD) values derived from the central 12 locations of the 24-2 visual field test (C24-2) to the entire 10-2 test for detecting central visual field abnormalities in eyes with, suspected of having, or at risk of having glaucoma.DesignCross-sectional case-control study.MethodsEyes with, suspected of having, or at risk of having glaucoma, based on masked grading of optic disc stereophotographs and/or ocular hypertension (intraocular pressure ≥ 22 mm Hg) were included as cases (n = 523). Eyes from healthy participants were included as controls (n = 107) to allow the 2 tests to be compared at matched specificities. The sensitivity to detect cases at 95% specificity using PSD values derived from the entire 10-2 test and C24-2 were compared.ResultsThe sensitivity of the 10-2 and C24-2 PSD values was not significantly different between the 10-2 and C24-2 at matched specificities (35.9% and 35.4% respectively; P = .900). There was also a substantial agreement between the cases detected by both methods (kappa = 0.80 ± 0.04), and a very strong association between the PSD values from the 2 methods (R2 = 0.91).Conclusions10-2 and 24-2 tests identified a similar number of eyes with, suspected of having, or at risk of having glaucoma as having central visual field abnormalities using PSD values. These findings do not mean that 10-2 tests are not useful, but highlight the need for further studies to determine the potential advantages of 10-2 tests through equivalent comparisons against 24-2 tests to ensure appropriate recommendations are made about its incorporation into the glaucoma standard of care.

Psychophysical inferences about the neural mechanisms supporting spatial vision can be undermined by uncertainties introduced by optical aberrations and fixational eye movements, particularly in fovea where the neuronal grain of the visual system is fine. We examined the effect of these preneural factors on photopic spatial summation in the human fovea using a custom adaptive optics scanning light ophthalmoscope that provided control over optical aberrations and retinal stimulus motion. Consistent with previous results, Ricco's area of complete summation encompassed multiple photoreceptors when measured with ordinary amounts of ocular aberrations and retinal stimulus motion. When both factors were minimized experimentally, summation areas were essentially unchanged, suggesting that foveal spatial summation is limited by postreceptoral neural pooling. We compared our behavioral data to predictions generated with a physiologically-inspired front-end model of the visual system, and were able to capture the shape of the summation curves obtained with and without pre-retinal factors using a single postreceptoral summing filter of fixed spatial extent. Given our data and modeling, neurons in the magnocellular visual pathway, such as parasol ganglion cells, provide a candidate neural correlate of Ricco's area in the central fovea.

Background: Deep brain stimulation (DBS) has become a well‑established treatment for the management of Parkinson’s disease (PD). The most common method of lead targeting utilizes microelectrode recording (MER) and intraoperative macrostimulation to confirm accurate placement of the lead. This has been significantly aided by the use of dexmedetomidine (DEX) sedation during the procedure. Despite the frequent use of DEX, it has been theorized that DEX may have some effects on the MER during intraoperative testing. The effect on the perception of sensory thresholds during macrostimulation in the form of paresthesia is still unreported. Objectives: To investigate the effect of the sedative DEX on sensory perception thresholds observed in the intraoperative versus postoperative settings for patients undergoing subthalamic nucleus (STN) DBS surgery for PD. Materials and Methods: Adult patients (n = 8) with a diagnosis of PD underwent placement of DBS leads (n = 14) in the STN. Patients were subjected to intraoperative macrostimulation for capsular and sensory thresholds prior to placement of each DBS lead. These were compared to sensory thresholds observed in the postoperative setting during outpatient programming at three depths on each lead (n = 42). Results: In most contacts (22/42) (P = 0.19), sensory thresholds for paresthesia perception were either perceived at a higher voltage or absent during intraoperative testing in comparison to those observed in the postoperative setting. Conclusions: DEX appears to have measurable (though not statistically significant) effect on the perception of paresthesia observed during intraoperative testing. [ABSTRACT FROM AUTHOR]

Purpose: After groin hernia repair (globally more than 20 million/year) 2– 4% will develop persistent severe pain (PSPG). Pain management is challenging and may require multimodal interventions, including re-surgery. Quantitative somatosensory testing (QST) is an investigational psychophysiological tool with the potential to uncover the pathophysiological mechanisms behind the pain, ie, revealing neuropathic or inflammatory components. The primary objective was to examine and describe the underlying pathophysiological changes in the groin areas by QST before and after re-surgery with mesh removal and selective neurectomy. Patients and Methods: Sixty patients with PSPG scheduled for re-surgery and with an inflammatory "component" indicated by blunt pressure algometry were examined in median (95% CI) 7.9 (5.8– 11.5) months before and 4.0 (3.5– 4.6) months after re-surgery. The QST-analyses included standardized assessments of cutaneous mechanical/thermal detection and pain thresholds. Suprathreshold heat stimuli were applied. Deep tissue sensitivity was tested by pressure algometry. Testing sites were the groin areas and the lower arm. Before/after QST data were z-transformed. Results: Re-surgery resulted in median changes in rest, average, and maximal pain intensity scores of − 2.0, − 2.5, and − 2.0 NRS (0/10) units, respectively (P = 0.0001), and proportional increases in various standardized functional scores (P = 0.0001). Compared with the control sites, the cutaneous somatosensory detection thresholds of the painful groin were increased before re-surgery and increased further after re-surgery (median difference: 1.28 z-values; P = 0.001), indicating a successive post-surgical loss of nerve fiber function ("deafferentation"). Pressure algometry thresholds increased after re-surgery (median difference: 0.30 z-values; P = 0.001). Conclusion: In this subset of patients with PSPG who underwent re-surgery, the procedure was associated with improved pain and functional outcomes. While the increase in somatosensory detection thresholds mirrors the surgery-induced cutaneous deafferentation, the increase in pressure algometry thresholds mirrors the removal of the deep "pain generator". The QST-analyses are useful adjuncts in mechanism-based somatosensory research. [ABSTRACT FROM AUTHOR]

In this study, the aroma profiles of high- and low-alcohol Jiangxiangxing Baijiu were compared through sensory analysis, revealing significant differences in acidic, floral, fruity, smoky and oxidized oil notes. To further clarify the underlying causes of aroma differences, we examined the concentrations of 106 important compounds, revealing that the concentrations differences between the two were generally 1 to 2 times. Furthermore, the determination results of the olfactory thresholds (OTs) indicated that the OT 40% vol of 87 aroma compounds was less than the OT 50% vol , with 68 compounds exhibiting OT changes ranging from 2 to 17 times. Finally, in terms of odor activity values (OAVs), it was established that changes in OTs of aroma compounds might be the primary reason behind the differences in aroma profiles. Overall, focusing on the impact of ethanol concentration on the OTs of aroma compounds is a key point of flavor modulation in low-alcohol Jiangxiangxing Baijiu., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Context: Understanding long-term outcomes and patient satisfaction with feminizing genitoplasty (FG) in patients with differences of sexual development (DSD) is crucial for optimizing treatment protocols., Objective: To evaluate long-term morphological and functional results and patients' satisfaction in a cohort of DSD patients submitted to FG., Design: Cross-sectional and retrospective cohort study conducted from 1965 to 2016 with follow-up assessments., Setting: Tertiary care center., Patients or Other Participants: Sixty DSD female patients, including 36 with congenital adrenal hyperplasia (CAH) and 24 with non-CAH DSD etiology, who underwent FG., Interventions: FG procedures were performed, and results were analyzed based on age at surgery and surgical techniques used., Main Outcome Measures: Surgical results, genital sensitivity, sexual function, and patient satisfaction., Results: Ninety-one percent of patients had normal clitoral size, and 85% had separated perineal orifices. Three patients with persistent urogenital sinus did not report symptoms. Genital sensitivity to mechanical and vibratory stimuli was similar to control groups. No CAH patients experienced overall sexual dysfunction, while 3 non-CAH patients and 4 control women reported reduced sexual desire and arousal. Eighty-nine percent of patients preferred surgery during childhood, and 97% were satisfied with their surgical outcomes., Conclusion: FG outcomes in this cohort were satisfactory, with no significant impact on genital sensitivity or sexual function. Most patients preferred early surgery and reported high satisfaction with the results. Further studies are needed to confirm these findings in broader populations., (© The Author(s) 2025. Published by Oxford University Press on behalf of the Endocrine Society.)

Introduction: Exposure to adverse childhood experiences (ACEs) is associated with a range of poor long-term health outcomes, including multimorbidity and chronic pain. Epidemiological evidence underpins much of this relationship; however, psychophysical testing methods, such as quantitative sensory testing (QST), may provide valuable insights into potential mechanisms. Previous studies have shown inconsistent links between ACEs and QST, but the QST profiles of people with multimorbidity have not been reported. We hypothesise that exposure to ACEs is associated with lowered QST thresholds (ie, experience of pain with milder stimuli) and that this association is stronger in adults with multimorbidity and/or chronic pain. The ACE-MAP study is a cross-sectional feasibility study with the primary aim of assessing the feasibility and acceptability of the proposed study procedures. The secondary aim is to generate preliminary data to understand the impact of ACEs on QST thresholds., Methods and Analysis: We plan to recruit 40 participants, with 10 in each of the following groups: (1) chronic pain with multimorbidity; (2) chronic pain without multimorbidity; (3) multimorbidity without chronic pain; and (4) controls. Participants will complete a series of questionnaires (including on ACEs, chronic pain and long-term conditions) and will then take part in QST assessments. The primary study outcomes will include measures of feasibility and acceptability of the proposed study design. The secondary study outcomes will include exploratory analysis on the relationship between ACEs and QST thresholds., Ethics and Dissemination: The study was approved by the Scotland B Research Ethics Committee (reference: 24/SS/0031). Results from the study will be presented at scientific conferences, published in a peer-reviewed journal and shared with patients and members of the public through other media streams., Trial Registration Number: ISRCTN10049430., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY. Published by BMJ Group.)

The texture of foods plays an important role in the liking of foods. Especially for picky eaters, texture can be a reason to reject foods. Previous studies showed that picky eaters in general dislike tactile stimulation more, which can include the feel of sand in their hands and specific food textures in their mouth. It has been suggested that this dislike stems from lower thresholds to detect touch, causing textures to feel over-stimulating and therefore more aversive. Alternatively, picky eaters might have the same objective tactile thresholds, but different subjective evaluations. The aim of the present study is to test the relations between tactile thresholds, liking of textures, food liking and picky eating. In a sample of 86 adult participants, picky eating was measured with the Adult Picky Eating Questionnaire (APEQ) and food liking with the Food Liking Questionnaire (FLQ). Tactile thresholds were tested with Semmes-Weinstein monofilaments (both on the tongue and fingertip) and liking of different textures was measured by feeling several textures with the hands. Results showed that both tongue and fingertip tactile thresholds were not related to the liking of textures. Thresholds of the fingertip, but not the tongue, were weakly related to food liking, but not directly to the APEQ. Liking of textures was related to both food liking and the APEQ. The results indicate that picky eaters indeed have a general subjective dislike of textures, but this cannot be explained by lower tactile thresholds. Future research might focus on how differential liking of textures develops., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare., (Copyright © 2024. Published by Elsevier Ltd.)

Introduction. Pain perception varies due to many factors. Quantitative sensory testing is a panel of diagnostic tests used to assess somatosensory function. The aim of the study was to determine how psychophysical variables are related to the perceived pain intensity in patients with chronic pain. Material and Methods. The cross-sectional study included 88 subjects (average age 51.3 ± 9.4 years, 76 (86.4%) women) diagnosed with chronic pain syndrome and fibromyalgia or chronic neuropathic pain associated with lumbosacral radiculopathy. Current and average pain intensities in the past 4 weeks were rated on a numerical rating scale. Quantitative sensory testing included pressure pain thresholds, heat pain thresholds, and cold pain thresholds. Patients filled out the Fear Avoidance Component Scale, a questionnaire that examines the fear avoidance phenomenon. Results. The highest correlations were found between the Fear Avoidance Component Scale scores and current and average pain intensity (r = 0.438 and r = 0.253, respectively); between pain duration and current and average pain intensity in the past 4 weeks (r = 0.340 and r = 0.308, respectively). Moderate and negative correlations were found between pressure pain thresholds and current and average pain intensity (r = - 0.233 and r = -0.300, respectively). Conclusion. Low to moderate, significant positive correlations were found between fear-avoidance and pain intensity. Significant but low negative correlations were found between pressure pain threshold and current pain intensity, as well as between pressure pain threshold and average pain intensity [ABSTRACT FROM AUTHOR]

Palatal sensation is important for articulation, feeding, and swallowing. However, palatal sensation in patients with cleft palate (CP) after palatoplasty has been investigated only inadequately because of the complexity and high costs of objective evaluation. This study compared the somatosensory evoked magnetic fields (SEFs) induced by electrical stimulation of the palates of patients with CP after palatoplasty and the palatal sensory thresholds (PSTs) of the stimulation with those of healthy (control) subjects. The CP group comprised 12 patients with unilateral cleft lip and palate (UCLP). The control group comprised 31 control subjects. No significant difference in intensity was found between them. Nevertheless, the PSTs in the UCLP group were significantly higher than those in the control group at all sites (p < 0.05). We infer that the electrical signals transmitted from palatal sensory receptors of patients with CP might be amplified by a compensation mechanism in the central nervous system. SEFs provide an effective method for objective evaluation of palatal sensation in patients with CP after palatoplasty. Evaluation of SEFs during palatal sensory stimulation in patients with CP after palatoplasty might lead to better corrective surgical methods that also preserve palatal sensation. • SEF latency in the palate is longer in UCLP patients than in healthy subjects. • SEF intensity shows no difference between UCLP patients and healthy subjects. • PSTs are higher in UCLP patients than in healthy subjects at all palate sites. • SEF measurement is an effective objective method for evaluating palatal sensation. [ABSTRACT FROM AUTHOR]

Introduction: Autonomic nervous system functioning is theorised to underpin individual differences in sensory processing, with a small amount of supporting evidence. Despite recognition of the need to measure the balance between sympathetic and parasympathetic activity, most studies have measured only one of these systems. This study investigated whether sensory processing patterns are related to autonomic balance for young adults at rest and in response to a sensory-based stressor. Method: In this cross-sectional laboratory study, 100 young adults completed the adolescent/adult sensory profile. Heart rate variability and pre-ejection period were recorded before, during and after a coldpressor task. Results: Relationships between sensory processing patterns and autonomic balance varied by gender. In males, low sensory thresholds were generally related to a state of reciprocal sympathetic activation. In females, low thresholds were associated with greater autonomic reactivity in response to the coldpressor. Conclusion: This study showed, for the first time in young adults, that sensory processing patterns may be linked to patterns of autonomic balance. Therapists should be aware that young men with low sensory thresholds may be more likely than others to exhibit a resting state of sympathetic hyperarousal and further research should investigate whether this impacts their daily functioning and wellbeing. [ABSTRACT FROM AUTHOR]

The transition from a healthy to a persistent severe pain state following otherwise successful elective surgery is a feared complication. Groin hernia repair, previously considered minor surgery, is a standard surgical procedure annually performed on 2,000 individuals per one million residents. A trajectory into persistent severe pain is, unfortunately, seen in 2-4%, severely impeding physical and psychosocial daily functions. [ABSTRACT FROM AUTHOR]

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Subretinal prostheses are designed to restore sight in patients blinded by retinal degeneration using electrical stimulation of the inner retinal neurons. To relate retinal output to perception, we studied behavioral thresholds in blind rats with photovoltaic subretinal prostheses stimulated by full-field pulsed illumination at 20 Hz, and measured retinal ganglion cell (RGC) responses to similar stimuli ex-vivo. Behaviorally, rats exhibited startling response to changes in brightness, with an average contrast threshold of 12%, which could not be explained by changes in the average RGC spiking rate. However, RGCs exhibited millisecond-scale variations in spike timing, even when the average rate did not change significantly. At 12% temporal contrast, changes in firing patterns of prosthetic response were as significant as with 2.3% contrast steps in visible light stimulation of healthy retinas. This suggests that millisecond-scale changes in spiking patterns define perceptual thresholds of prosthetic vision. Response to the last pulse in the stimulation burst lasted longer than the steady-state response during the burst. This may be interpreted as an excitatory OFF response to prosthetic stimulation, and can explain behavioral response to decrease in illumination. Contrast enhancement of images prior to delivery to subretinal prosthesis can partially compensate for reduced contrast sensitivity of prosthetic vision.

Reduced global motion sensitivity, relative to global static form sensitivity, has been found in children with many neurodevelopmental disorders, leading to the "dorsal stream vulnerability" hypothesis (Braddick et al., 2003). Individual differences in typically developing children's global motion thresholds have been shown to be associated with variations in specific parietal cortical areas (Braddick et al., 2016). Here, in 125 children aged 5-12years, we relate individual differences in global motion and form coherence thresholds to fractional anisotropy (FA) in the superior longitudinal fasciculus (SLF), a major fibre tract communicating between parietal lobe and anterior cortical areas. We find a positive correlation between FA of the right SLF and individual children's sensitivity to global motion coherence, while FA of the left SLF shows a negative correlation. Further analysis of parietal cortical area data shows that this is also asymmetrical, showing a stronger association with global motion sensitivity in the left hemisphere. None of these associations hold for an analogous measure of global form sensitivity. We conclude that a complex pattern of structural asymmetry, including the parietal lobe and the superior longitudinal fasciculus, is specifically linked to the development of sensitivity to global visual motion. This pattern suggests that individual differences in motion sensitivity are primarily linked to parietal brain areas interacting with frontal systems in making decisions on integrated motion signals, rather than in the extra-striate visual areas that perform the initial integration. The basis of motion processing deficits in neurodevelopmental disorders may depend on these same structures.

A remarkable feature of human vision is that the retina and brain have evolved circuitry to extract useful spatial and spectral information from signals originating in a photoreceptor mosaic with trichromatic constituents that vary widely in their relative numbers and local spatial configurations. A critical early transformation applied to cone signals is horizontal-cell-mediated lateral inhibition, which imparts a spatially antagonistic surround to individual cone receptive fields, a signature inherited by downstream neurons and implicated in color signaling. In the peripheral retina, the functional connectivity of cone inputs to the circuitry that mediates lateral inhibition is not cone-type specific, but whether these wiring schemes are maintained closer to the fovea remains unsettled, in part because central retinal anatomy is not easily amenable to direct physiological assessment. Here, we demonstrate how the precise topography of the long (L)-, middle (M)-, and short (S)-wavelength-sensitive cones in the human parafovea (1.5° eccentricity) shapes perceptual sensitivity. We used adaptive optics microstimulation to measure psychophysical detection thresholds from individual cones with spectral types that had been classified independently by absorptance imaging. Measured against chromatic adapting backgrounds, the sensitivities of L and M cones were, on average, receptor-type specific, but individual cone thresholds varied systematically with the number of preferentially activated cones in the immediate neighborhood. The spatial and spectral patterns of these interactions suggest that interneurons mediating lateral inhibition in the central retina, likely horizontal cells, establish functional connections with L and M cones indiscriminately, implying that the cone-selective circuitry supporting red-green color vision emerges after the first retinal synapse.SIGNIFICANCE STATEMENT We present evidence for spatially antagonistic interactions between individual, spectrally typed cones in the central retina of human observers using adaptive optics. Using chromatic adapting fields to modulate the relative steady-state activity of long (L)- and middle (M)-wavelength-sensitive cones, we found that single-cone detection thresholds varied predictably with the spectral demographics of the surrounding cones. The spatial scale and spectral pattern of these photoreceptor interactions were consistent with lateral inhibition mediated by retinal horizontal cells that receive nonselective input from L and M cones. These results demonstrate a clear link between the neural architecture of the visual system inputs-cone photoreceptors-and visual perception and have implications for the neural locus of the cone-specific circuitry supporting color vision.

Human vision is exquisitely sensitive-a dark-adapted observer is capable of reliably detecting the absorption of a few quanta of light. Such sensitivity requires that the sensory receptors of the retina, rod photoreceptors, generate a reliable signal when single photons are absorbed. In addition, the retina must be able to extract this information and relay it to higher visual centres under conditions where very few rods signal single-photon responses while the majority generate only noise. Critical to signal transmission are mechanistic optimizations within rods and their dedicated retinal circuits that enhance the discriminability of single-photon responses by mitigating photoreceptor and synaptic noise. We describe behavioural experiments over the past century that have led to the appreciation of high sensitivity near absolute visual threshold. We further consider mechanisms within rod photoreceptors and dedicated rod circuits that act to extract single-photon responses from cellular noise. We highlight how these studies have shaped our understanding of brain function and point out several unresolved questions in the processing of light near the visual threshold.This article is part of the themed issue 'Vision in dim light'.

Chronic pain associated with temporomandibular disorders (TMDs) may reflect muscle mechanoreceptor afferent barrage and dysregulated sensory processing. This observational study tested for associations between Characteristic Pain Intensity (CPI), physical symptoms (Patient Health Questionnaire–15 [PHQ-15]), and cumulative jaw muscle motor load (mV*s). In accordance with institutional review board oversight and Strengthening the Reporting of Observational Studies in Epidemiology guidelines, adult subjects gave informed consent and were identified via Diagnostic Criteria for TMD (DC-TMD) examination and research protocols. Subjects were assigned to ±Pain groups using DC-TMD criteria for myalgia. CPI scores characterized pain intensity. PHQ-15 scores were surrogate measures of dysregulated sensory processing. Laboratory tests were performed to quantify masseter and temporalis muscle activities (mV) per bite force (N) for each subject. In their natural environments, subjects recorded day- and nighttime electromyography from which cumulative jaw muscle motor loads (mV*s) were determined for activities consistent with bite forces of >1 to ≤2 and >2 to ≤5 N. Data were assessed using univariate analysis of variance, simple effects tests, K-means cluster classification, and 3-dimensional regression analyses. Of 242 individuals screened, 144 enrolled, and 125 with complete data from study protocols, there were 35 females and 15 males for +Pain and 35 females and 40 males for −Pain. Subjects produced 324 daytime and 341 nighttime recordings of average duration 6.9 ± 1.7 and 7.6 ± 1.7 h, respectively. Overall, +Pain compared to −Pain subjects had significantly higher (all P ≤ 0.002) CPI and PHQ-15 scores. Cumulative jaw muscle motor loads showed significant between-subject effects for time, diagnostic group, and sex (all P < 0.003), where motor loads tended to be higher for daytime versus nighttime, +Pain versus −Pain groups, and males versus females. Two clusters were identified, and regression relations showed associations of low-magnitude daytime masseter motor load, PHQ-15, and CPI scores for cluster 1 (n = 105, R 2 = 0.44) and cluster 2 (n = 18, R 2 = 0.80). Furthermore, these regression relations showed thresholds of motor load and PHQ-15 scores, above which there were nonlinear increases in reported pain. [ABSTRACT FROM AUTHOR]

Introduction: Scalds account for 40 % of burn injuries in developed countries, with a subset occurring during caregiving activities, particularly when gloves are worn. Gloves, a standard precaution against infection and body fluid exposure, may impair sensory feedback critical for detecting temperature changes, potentially increasing the risk of burns during personal care tasks., Methods: This study investigated the impact of glove use on heat perception. Twelve healthy participants (6 male, 6 female) immersed their index fingers in water baths set at 40°C, 45°C, 50°C, 55°C, and 60°C. Heat perception thresholds were assessed under three conditions: no gloves, single gloves, and double gloves. Participants withdrew their fingers upon feeling discomfort, and the withdrawal temperatures were recorded., Results: Our trial showed that gloves significantly delayed heat discomfort detection, with the longest delays observed at 50°C and 55°C when double gloves were worn. Wearing a single glove raised the discomfort threshold by approximately 5°C, while double gloves increased it by 10°C. This logarithmic relationship between temperature and perception delay indicates a substantial sensory alteration, especially at higher temperatures., Conclusion: The findings underscore the heightened risk of scald injuries in vulnerable individuals due to delayed heat detection caused by gloves. Awareness of altered temperature thresholds during glove use is essential to prevent burns during caregiving tasks, particularly in activities requiring precise temperature assessment, such as bathing or showering. Enhanced education and preventive measures are crucial for ensuring safety in these contexts., Competing Interests: Conflict of Interest P. Dziewulski is a member of the editorial board of Burns. The Authors declare no other conflicts of interest in relation to this work., (Copyright © 2025 Elsevier Ltd and International Society of Burns Injuries. All rights reserved.)

Mechanical sensitivity is commonly affected in chronic pain and other neurological disorders. To discover mechanisms of individual differences in punctate mechanosensation, we performed quantitative trait locus (QTL) mapping of the response to von Frey monofilament stimulation in BXD recombinant inbred (BXD) mice. Significant loci were detected on mouse chromosome (Chr) 5 and 15, indicating the location of underlying polymorphisms that cause heritable variation in von Frey response. Convergent evidence from public gene expression data implicates candidate genes within the loci: von Frey thresholds were strongly correlated with baseline expression of Cacna2d1, Ift27 and Csnk1e in multiple brain regions of BXD strains. Systemic gabapentin and PF-670462, which target the protein products of Cacna2d1 and Csnk1e, respectively, significantly increased von Frey thresholds in a genotype-dependent manner in progenitors and BXD strains. Real-time polymerase chain reaction confirmed differential expression of Cacna2d1 and Csnk1e in multiple brain regions in progenitors and showed differential expression of Cacna2d1 and Csnk1e in the dorsal root ganglia of the progenitors and BXD strains grouped by QTL genotype. Thus, linkage mapping, transcript covariance and pharmacological testing suggest that genetic variation affecting Cacna2d1 and Csnk1e may contribute to individual differences in von Frey filament response. This study implicates Cacna2d1 and Ift27 in basal mechanosensation in line with their previously suspected role in mechanical hypersensitivity. Csnk1e is implicated for von Frey response for the first time. Further investigation is warranted to identify the specific polymorphisms involved and assess the relevance of these findings to clinical conditions of disturbed mechanosensation.

The spatial extent of interference from nearby object or contours (the critical spacing of "crowding") has been thoroughly characterized across the visual field, typically using high contrast achromatic stimuli. However, attempts to link this measure with known properties of physiological pathways have been inconclusive. The S-cone pathway, with its ease of psychophysical isolation and known anatomical characteristics, offers a unique tool to gain additional insights into crowding. In this study, we measured the spatial extent of crowding in the S-cone pathway at several retinal locations using a chromatic adaptation paradigm. S-cone crowding was evident and extensive, but its spatial extent changed less markedly as a function of retinal eccentricity than the extent found using traditional achromatic stimuli. However, the spatial extent agreed with that of low contrast achromatic stimuli matched for isolated resolvability. This suggests that common cortical mechanisms mediate the crowding effect in the S-cone and achromatic pathway, but contrast is an important factor. The low contrast of S-cone stimuli makes S-cone vision more acuity-limited than crowding-limited.

Nearby collinear flankers increase the false alarm rate (reports of the target being present when it is not) in a Yes-No experiment. This effect has been attributed to "filling-in" of the target location due to increased activity induced by the flankers. According to signal detection theory, false alarms are attributed to noise in the visual nervous system. Here we investigated the effect of external noise on the filling-in effect by adding white noise to a low contrast Gabor target presented between two collinear Gabor flankers at a range of target-flanker separations. External noise modulates the filling-in effect, reducing visual sensitivity (d') and increasing the filling-in effect (False Alarm rate). We estimated the amount of external noise at which the false alarm rate increases by the √2 (which we refer to as NFA). Across flank distances, both the false alarm rate and d' (with no external noise) are correlated with NFA. These results are consistent with the notion that nearby collinear flankers add both signal and noise to the target location. The increased signal results in higher d' values; the increased noise to higher false alarm rates (the filling effect).

This study offers insights into the complex relationship between chemical species constituting air pollution and chemosensory function. We examined the relationship between chemical species known to contribute to air pollution and assault human health and chemosensory sensitivity. Chemosensory sensitivity data was retrieved from a large-scale study involving 711 urban-dwelling participants inhabiting 10 different regions of the globe. Their olfactory threshold towards phenyl ethyl alcohol (PEA) and olfactory/trigeminal threshold towards Eucalyptol was measured in a multicentre study. We matched the individual chemosensory data with the levels of PM2.5, PM10, O3, NO2, SO2, CO at the location of testing sites, on the exact date of the test, using EMAC (ECHAM5/MESSy for Atmospheric Chemistry) model. Our findings indicate that air pollution negatively affects olfactory function and has cumulative negative effects with aging. The reported patterns are seasonal and increase during Autumn and Winter, and interact with medical conditions related to poorer olfactory function. We extend the current knowledge by demonstrating that olfactory/trigeminal perception is also disrupted by toxic air, albeit in a slightly different manner. The analyzed models promote a more complex perspective on the relationship between air composition and chemosensory sensitivity, but delineate problems related to the interdependence of the levels of chemical species constituting air pollution and using them together to predict chemosensory sensitivity. Conclusions point to the need to investigate the problem of air pollution and chemosensory health from a global perspective, as air quality partly accounts for the differences in chemosensory perception in different regions of the world., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Aims: Diabetic patients are at elevated risk of neuropathy; early detection is desirable to minimise the risk of complications. The Medipin pin-prick device was appraised as a screening tool for diabetic neuropathy., Methods: Prospective cross-sectional comparative screening study in primary care setting, involving 389 participants with type 2 diabetes mellitus. The Medipin pin-prick method, involving dorsal application on the hallux of both feet, was compared to 10 g monofilament testing., Results: The ternary and semi-quantitative approach for scoring Medipin pin-prick sensation give very similar results (Spearman rho 0.67, P < 0.001). A total of 59 % patients had no signs of neuropathy (sharp sensation), 38 % reported impaired sensation (dull sensation), and an absence of sensation occurred in 3 % of patients. For the monofilament dorsal method, the figures were 79 % no neuropathy, 14 % elevated risk, and 7 % neuropathy respectively, and with the monofilament plantar method 87 % of patients had no neuropathy and 13 % did. Correlation analyses showed that taller patients and those with existing neuropathic pain are at very modest increased risk of neuropathy., Conclusions: The Medipin pin-prick device can identify diabetic neuropathy and detects (first signs of) neuropathy in relatively more patients than 10 g monofilament testing. The differential targeting of nerve types, namely predominant small (Medipin) versus large (monofilament) fibre, likely underpins the difference in outcomes., Competing Interests: Declaration of Competing Interest None to declare., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The low-prevalence effect (LPE) is the finding that target detection rates decline as targets become less frequent in a visual search task. A major source of this effect is thought to be that fewer targets result in lower quitting thresholds, i.e., observers respond target-absent after looking at fewer items compared to searches with a higher prevalence of targets. However, a lower quitting threshold does not directly account for an LPE in searches where observers continuously monitor a dynamic display for targets. In these tasks there are no discrete "trials" to which a quitting threshold could be applied. This study examines whether the LPE persists in this type of dynamic search context. Experiment 1 was a 2 (dynamic/static) x 2 (10%/40% prevalence targets) design. Although overall performance was worse in the dynamic task, both tasks showed a similar magnitude LPE. In Experiment 2, we replicated this effect using a task where subjects searched for either of two targets (Ts and Ls). One target appeared infrequently (10%) and the other moderately (40%). Given this method of manipulating prevalence rate, the quitting threshold explanation does not account for the LPE even for static displays. However, replicating Experiment 1, we found an LPE of similar magnitude for both search scenarios, and lower target detection rates with the dynamic displays, demonstrating the LPE is a potential concern for both static and dynamic searches. These findings suggest an activation threshold explanation of the LPE may better account for our observations than the traditional quitting threshold model., Competing Interests: Declarations: The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, nor the US Government. Conflict of interest: All authors declare that they have no conflicts of interest. Ethics approval: The study protocol was approved by the Michigan State University in compliance with all applicable Federal regulations governing the protection of human subjects. Consent to participate: Informed consent was obtained from all individual participants included in the study. Consent for publication: Dr. Bolkhovsky is an employee of the US Government. This work was prepared as part of his official duties. Title 17 U.S.C. §105 provides that ‘Copyright protection under this title is not available for any work of the United States Government.’ Title 17 U.S.C. §101 defines a US Government work as a work prepared by a military Service member or employee of the US Government as part of that person’s official duties., (© 2024. The Author(s).)

Background: Amidst the rise of frailty among a globally aging population, olfactory decline has emerged as a harbinger of frailty and mortality in population-level studies. However, the relationships between frailty and the olfactory subdomains of identification (OI), discrimination (OD), and threshold (OT) remain unexplored. This study prospectively examined the association between olfactory subdomains and the physical frailty phenotype (PFP) to investigate olfactory evaluation as a means of frailty screening., Methods: A case‒control study of 45 frail and 45 non-frail individuals matched by age and sex. OT, OD, OI (range 0‒16), and composite sum (threshold, discrimination, and identification scores [TDI], range 0‒48) were measured with Sniffin' Sticks. PFP was defined by presence of three or more criteria: physical inactivity, self-reported exhaustion, muscle weakness, slow gait, and unintentional weight loss. Conditional logistic regression evaluated associations between olfactory subdomains and frailty., Results: Ninety individuals with mean age of 83.1 ± 4.9 years, 60% female (n = 54), and 87.8% white (n = 79) were included. Olfactory scores were significantly lower in the frail group for OI (9.2 vs. 12.1, p < 0.001), OD (8.1 vs. 11.6, p < 0.001), OT (4.4 vs. 8.5, p < 0.001), and TDI (21.7 vs. 32.2, p < 0.001) than in the non-frail group. A single-point decrease in olfactory score was associated with increased odds of frailty in OT (odds ratio [OR]: 2.21, 95% confidence interval: [1.22, 3.98]), OD (OR: 2.19, 95% CI: [1.32, 3.65]), OI (OR: 2.29, 95% CI: [1.19, 4.39]), and TDI (OR: 1.54, 95% CI: [1.14, 2.08])., Conclusion: The robust association between olfactory subdomain scores and frailty suggests that olfaction may be an accessible signifier of frailty. Future studies should investigate this relationship longitudinally to assess predictive relationships., (© 2024 ARS‐AAOA, LLC.)

The effects of signal and noise on contrast discrimination are difficult to separate because of a singularity in the signal-detection-theory model of two-alternative forced-choice contrast discrimination (Katkov, Tsodyks, & Sagi, 2006). In this article, we show that it is possible to eliminate the singularity by combining that model with a binocular combination model to fit monocular, dichoptic, and binocular contrast discrimination. We performed three experiments using identical stimuli to measure the perceived phase, perceived contrast, and contrast discrimination of a cyclopean sine wave. In the absence of a fixation point, we found a binocular advantage in contrast discrimination both at low contrasts (

Age-related changes in chromatic discrimination along dichromatic confusion lines were measured with the Cambridge Colour Test (CCT). One hundred and sixty-two individuals (16 to 88 years old) with normal Rayleigh matches were the major focus of this paper. An additional 32 anomalous trichromats classified by their Rayleigh matches were also tested. All subjects were screened to rule out abnormalities of the anterior and posterior segments. Thresholds on all three chromatic vectors measured with the CCT showed age-related increases. Protan and deutan vector thresholds increased linearly with age while the tritan vector threshold was described with a bilinear model. Analysis and modeling demonstrated that the nominal vectors of the CCT are shifted by senescent changes in ocular media density, and a method for correcting the CCT vectors is demonstrated. A correction for these shifts indicates that classification among individuals of different ages is unaffected. New vector thresholds for elderly observers and for all age groups are suggested based on calculated tolerance limits.

PurposeThe contrast sensitivity function (CSF) provides a detailed description of an individual's spatial-pattern detection capability. We tested the hypothesis that the CSFs of people with low vision differ from a "normal" CSF only in their horizontal and vertical positions along the spatial frequency (SF) and contrast sensitivity (CS) axes.MethodsContrast sensitivity for detecting horizontal sinewave gratings was measured with a two temporal-interval forced-choice staircase procedure, for a range of SFs spanning 5 to 6 octaves, for 20 low-vision observers and five adults with normal vision. An asymmetric parabolic function was used to fit the aggregate data of the normal-vision observers, yielding the "normal template." Each of the 20 low-vision CSFs was fit in two ways, by using a shape-invariant version of the normal template (with the width parameters fixed) that was shifted along the log-SF and log-CS axes, and by an unconstrained asymmetric parabolic function ("free-fit").ResultsThe two fitting methods yielded values of the peak CS, the SF corresponding to peak CS, and the high cut-off SF that were highly correlated and in good agreement with each other. In addition, the width parameters of the low-vision CSFs were comparable with those of the normal template, implying that low-vision CSFs are similar in shape to the normal CSF.ConclusionsThe excellent agreement of parameters estimated by the two fitting methods suggests that low-vision CSFs can be approximated by a normal CSF shifted along the log-SF and log-CS axes to account for the impaired acuity and contrast sensitivity.

BackgroundVisual acuity is measured by diminishing letter size till recognition threshold is reached, letters varying in legibility. In this experiment, size reduction was compared with other means of handicapping letter legibility.MethodsIn five normal observers, discrimination thresholds for 13 sans-serif capital letters in a 5 × 4 format were obtained by a staircase procedure for size reduction, as well as for 20 minutes of arc (logMAR = 0.6) letters subjected to four kinds of image degradation: reducing contrast, convolving with blurring spread, embedding in noise and perturbing contour smoothness.ResultsThreshold correlation and distribution of response errors show prominent differences and indicate the degree to which the visual processing of the various modes of image degradation is distinct.ConclusionsThe validation of four other ways of impairing the recognition of optotypes in addition to size diminution reveals their potential in the differential diagnosis of defects in pattern detection, in evaluating therapeutic regimens and in developing concepts of form perception.

Aims: To investigate how trait anxiety and stress jointly affect the sensory and jaw motor responses to a tonic orofacial nociceptive stimulus. Methods: Orthodontic separators were placed between the first molars in 45 adults with low (n = 14), intermediate (n = 17), and high (n = 14) trait anxiety. Tooth pain, occlusal discomfort, tooth clenching (as a jaw motor behavior), and situational stress were measured three times a day for 5 days using visual analog scales. Mixed-effects regression models were used to evaluate the sensory and motor outcome measures. Results: Pain, discomfort, and frequency of tooth-clenching trajectories were affected by trait anxiety (P = .007, P < .001, and P = .055, respectively) and stress (P < .001, P < .001, and P = .044, respectively). Individuals with high anxiety reported their highest pain (17.7 ± 2.9 mm) and discomfort (35.2 ± 4.1 mm) 24 hours earlier than those with low anxiety (pain: 15.9 ± 2.6 mm, discomfort: 28.8 ± 3.7 mm). Tooth clenching decreased progressively in response to the stimulus (P < .001). Conclusion: A tonic orofacial nociceptive stimulus triggers an avoidance jaw motor behavior. Both trait anxiety and situational stress heighten the sensory response to such a stimulus, but weakly affect the motor response to it. [ABSTRACT FROM AUTHOR]