Assessing Visual Crowding in Participants With Preperimetric Glaucoma Using Eye Movement and Manual Response Paradigms.

Purpose: Crowding is the inability to distinguish objects in the periphery in the presence of clutter. Previous studies showed that crowding is elevated in patients with glaucoma. This could serve as an indicator of the functional visual performance of patients with glaucoma but at present appears too time-consuming and attentionally demanding. We examined visual crowding in individuals with preperimetric glaucoma to compare the potential effectiveness of eye movement-based and manual response paradigms. Methods: We assessed crowding magnitude in 10 participants with preperimetric glaucoma and 10 age-matched controls. Crowding magnitudes were assessed using four different paradigms: a conventional two-alternative forced choice (2AFC) manual, a 2AFC and a six-alternative forced choice (6AFC) eye movement, and a serial search paradigm. All paradigms measured crowding magnitude by comparing participants' orientation discrimination thresholds in isolated and flanked stimulus conditions. Moreover, assessment times and participant preferences were compared across paradigms. Results: Patients with preperimetric glaucoma exhibited elevated crowding, which was most evident in the manual-response paradigm. The serial search paradigm emerged as the fastest method for assessing thresholds, yet it could not effectively distinguish between glaucoma and control groups. The 6AFC paradigm proved challenging for both groups. Conclusions: We conclude that patients with preperimetric glaucoma demonstrate heightened binocular visual crowding. This is most effectively demonstrated via the 2AFC manual response paradigm. The additional attentional demand in eye movement paradigms rendered them less effective in the elderly population of the present study. Translational Relevance: Our findings underscore both the value and the complexity of efficiently evaluating crowding in elderly participants, including those with preperimetric glaucoma.

[Adaptation for use In Russia of the extended odor identification Sniffin' Sticks test]. / Kul'tural'naya adaptatsiya testa na identifikatsiyu zapakhov Sniffin' Sticks dlya ispol'zovaniya v Rossii.

The psychophysical Sniffin' Sticks test, which includes an odor identification test, is the gold standard for assessing the sense of smell in clinical and scientific practice. A necessary requirement for the odor identification test is a close familiarity with the odors used by the inhabitants of the region in which it is used. We studied 77 healthy volunteers and 51 patients with olfactory dysfunction and we found that Russians are not familiar with the three smells from the test (licorice, turpentine and anise) and are completely unfamiliar with the one proposed alternative answer (chives). Moreover, four odors demonstrated very low recognition (less than 75%). The test has been adapted for the use In Russia. In the booklet, licorice is replaced by cough syrup, turpentine by paint thinner, and chives by bay leaf. For odors with low recognition (lemon, apple, pineapple), the alternative fruity odors in the booklet were replaced with more contrasting ones. Based on the data obtained, we are going to develop a domestic version of the odor identification test.

[Development and validation of Russian olfactory test]. / Otechestvennyi obonyatel'nyi test: razrabotka i validizatsiya.

Olfactory disorders is one of the first symptoms of diseases from various departments of medicine (otorhinolaryngology, psychology, neurology, etc.). Based on international clinical recommendations, olfactory tests are the gold standard for the diagnosis of olfactory disorders. There are many different psychophysical tests: UPSIT (USA, Pennsylvania), Sniffin' Sticks test (Germany), BAST-24 (Spain), etc. Currently, there is an acute shortage of olfactory tests available for clinical practice In Russia. This problem is related to the fact that there are no olfactory tests registered as medical devices on the territory of the Russian Federation. Also, a significant limitation is the unrecognizability of odors by the population of our country, which include foreign analogues (licorice, anise, turpentine, etc.). OBJECTIVE: To develop and validate the national olfactory test on healthy volunteers. MATERIAL AND METHODS: The development and validation of the olfactory test included several stages. First, the development of an olfactory test was carried out, the selection of aromas to assess the threshold and identification ability of olfaction. 25 dilutions of n-butanol were used for the assessment of the threshold olfactory ability. For the stage of assessing the identification ability of the sense of smell, in our previous study, an assessment of the recognition of odor names in the territory of the Russian Federation was carried out. A total of 3.000 people from 8 federal districts of the Russian Federation were interviewed. During the development of the test, 20 names of flavors with the highest rating were used. By the 8th, the selection of monocomponent substances was carried out. Commercially available certified food and perfume flavorings have been used for fragrances whose equivalent in the test cannot be a monocomponent substance. A group of 25 healthy volunteers selected a flavor or a monocomponent for each of the 20 positions. To carry out the identification stage of testing, a booklet was developed with answer options for each fragrance, including 80 images associated with the smell. A methodology for conducting diagnostics has been created. Next, the validation of the developed olfactory test was carried out on 150 healthy volunteers. The study included an assessment of the threshold and identification ability of the sense of smell using the developed test and conducting a comparative analysis with a set of flavors and descriptors corresponding to the Sniffin' Sticks test. RESULTS: The developed test includes: 2 panels - panel 1 to assess the threshold ability of smell, panel 2 to assess the identification ability of smell, a booklet with 80 images and captions to them. The norms of threshold and identification olfactory abilities were also determined in the developed test. The domestic test was validated against the relative foreign Sniffin' Sticks test. Spearman's correlation between the accuracy values of the domestic test (17-20; 85.00-100.00%) and the values of the foreign test (11-16; 68.75-100.00%) did not reveal statistically significant differences (rs=0.065, p=0.432), which confirms the equally effective assessment of olfactory ability by the domestic olfactory test in comparison with its foreign counterpart. CONCLUSION: In this work, a methodology for the use of Russian olfactory test was developed and validated on healthy volunteers. The features of the developed test are an assessment of the threshold and identification ability of smell, an adapted set of odors for the Russian population, the use of paper blotters when applying flavor and visual images of descriptors. Despite the wide variety of psychophysical tests, this problem requires further study and comparative analysis of olfactory tests available In Russia and foreign analogues in order to obtain a universal and effective diagnostic method for the populations of our country.This work was supported by the Russian Foundation for Basic Research (Project No. 24-25-00415).

Hot topic: Mapping of the human intranasal mucosal thermal sensitivity: A clinical study on thermal threshold and trigeminal receptors.

INTRODUCTION: The olfactory and trigeminal system are closely interlinked. Existing literature has primarily focused on characterizing trigeminal stimulation through mechanical and chemical stimulation, neglecting thermal stimulation thus far. The present study aimed to characterize the intranasal sensitivity to heat and the expression of trigeminal receptors (transient receptor potential channels, TRP). METHODS: A total of 20 healthy participants (aged 21-27 years, 11 women) were screened for olfactory function and trigeminal sensitivity using several tests. Under endoscopic control, a thermal stimulator was placed in 7 intranasal locations: anterior septum, lateral vestibulum, interior nose tip, lower turbinate, middle septum, middle turbinate, and olfactory cleft to determine the thermal threshold. Nasal swabs were obtained in 3 different locations (anterior septum, middle turbinate, olfactory cleft) to analyze the expression of trigeminal receptors TRP: TRPV1, TRPV3, TRPA1, TRPM8. RESULTS: The thermal threshold differed between locations (p = 0.018), with a trend for a higher threshold at the anterior septum (p = 0.092). There were no differences in quantitative receptor expression (p = 0.46) at the different sites. The highest overall receptor RNA expression was detected for TRPV1 over all sites (p<0.001). The expression of TRPV3 was highest at the anterior septum compared to the middle turbinate or the olfactory cleft. The thermal sensitivity correlated with olfactory sensitivity and results from tests were related to trigeminal function like intensity ratings of ammonium, a questionnaire regarding trigeminal function, nasal patency, and CO2 thresholds. However, no correlation was found between receptor expression and psychophysical measures of trigeminal function. DISCUSSION: This study provided the first insights about intranasal thermal sensitivity and suggested the presence of topographical differences in thermal thresholds. There was no correlation between thermal sensitivity and trigeminal mRNA receptor expression. However, thermal sensitivity was found to be associated with psychophysical measures of trigeminal and olfactory function.

Perceptibility and acceptability thresholds for color differences of light and dark maxillofacial skin replications.

The aim of this study was to assess the perceptibility and acceptability thresholds of maxillofacial silicones for light and dark skin colors and to evaluate the effect of gender and professional experience on these thresholds. Two different sets of specimens (as light and dark) each, consisting of 14 (25 × 25 × 6-mm3) silicone skin replications, were produced. Four specimens of each set were produced from the same silicon mixture of the relevant set and polymerized simultaneously to provide standardized fabrication conditions. These 4 light/dark specimens were assigned as "baseline color specimens (BCs)" in each set, while the other 10 specimens were produced with a color difference level that increased gradually from BC. These stepped levels were obtained by controlled increasing of the pigment concentration in the relevant baseline silicon mixture. Color difference levels of specimens were calculated by using the CIELAB and CIEDE2000 formulas. Observers comprised of 3 different professional experiences as first-year dental students, interns, and dentists (n = 30/group, gender-balanced) were included. Combinations consisting of 5 specimens with 4 BCs and 1 different color were shown to the observers to assess whether the color difference was perceptible or acceptable. Perceptibility and acceptability percentages were regressed with color difference levels to estimate the best fit curve and confidence intervals were calculated (α = 0.05). The highest estimation of the coefficient of determination (R2) was found in the cubic curve for all parameters. A significant difference was found between the light and dark colors. The perceptibility thresholds (ΔE*ab/ΔE00) were 0.8/0.59 and 2.63/1.75 for light and dark colors, respectively. The acceptability thresholds (ΔE*ab/ΔE00) were 3.35/2.25, 10.07/7.04 for light and dark colors, respectively. No significant differences were found between gender and among experience groups concerning visual thresholds. Regardless of gender and experience, observers could perceive color differences more easily in light skin colors.

Psychophysics of neon color spreading: Chromatic and temporal factors are not limiting.

Neon color spreading (NCS) is an illusory color phenomenon that provides a dramatic example of surface completion and filling-in. Numerous studies have varied both spatial and temporal aspects of the neon-generating stimulus to explore variations in the strength of the effect. Here, we take a novel, parametric, low-level psychophysical approach to studying NCS in two experiments. In Experiment 1, we test the ability of both cone-isolating and equiluminant stimuli to generate neon color spreading for both increments and decrements in cone modulations. As expected, sensitivity was low to S(hort-wavelength) cone stimuli due to their poor spatial resolution, but sensitivity was similar for the other color directions. We show that when these differences in detection sensitivity are accounted for, the particular cone type, and the polarity (increment or decrement), make little difference in generating neon color spreading, with NCS visible at about twice detection threshold level in all cases. In Experiment 2, we use L-cone flicker modulations (reddish and greenish excursions around grey) to study sensitivity to NCS as a function of temporal frequency from 0.5 to 8 Hz. After accounting for detectability, the temporal contrast sensitivity functions for NCS are approximately constant or even increase over the studied frequency range. Therefore there is no evidence in this study that the processes underlying NCS are slower than the low-level processes of simple flicker detection. These results point to relatively fast mechanisms, not slow diffusion processes, as the substrate for NCS.

Age related changes in skin sensitivity assessed with smartphone vibration testing.

The capacity to perceive tactile input at the fingertips, referred to as tactile sensitivity, is known to diminish with age due to regressive changes to mechanoreceptor density and morphology. Sensitivity is measured as perceptual responses to stimuli of varying intensity. Contrary to traditional sensitivity monitoring instruments, smartphones are uniquely suited for remote assessment and have shown to deliver highly calibrated stimuli along a broad spectrum of intensity, which may improve test reliability. The aim of this study was to evaluate a vibration-emitting smartphone application, the Vibratus App, as a mode of estimating tactile sensory thresholds in the aging adult. The peripheral nerve function of 40 neurologically healthy volunteers (ages 18-71) was measured using monofilaments, a 128-Hz tuning fork, the Vibratus App, and nerve conduction studies (NCS). Between group differences were analyzed to determine each measurement's sensitivity to age. Spearman correlation coefficients depicted the associative strength between hand-held measurements and sensory nerve action potential (SNAP) amplitude. Inter-rater reliability of traditional instruments and the software-operated smartphone were assessed by intraclass correlation coefficient (ICC2,k). Measurements taken with Vibratus App were significantly different between age groups (p < 0.001). The inter-rater reliability of monofilament, smartphone vibration, and tuning fork testing was moderate to good (ICC2,k = 0.65, 0.69, and 0.79, respectively). The findings of this study support further investigation of smartphones as sensitivity monitoring devices for at home monitoring of skin sensitivity.

Children and adolescents with primary headaches exhibit altered sensory profiles - a multi-modal investigation.

BACKGROUND: Pediatric headache is an increasing medical problem that has adverse effects on children's quality of life, academic performance, and social functioning. Children with primary headaches exhibit enhanced sensory sensitivity compared to their healthy peers. However, comprehensive investigations including multimodal sensory sensitivity assessment are lacking. This study aimed to compare sensory sensitivity of children with primary headaches with their healthy peers across multiple sensory domains. METHODS: The study included 172 participants aged 6 to 17 years (M = 13.09, SD = 3.02 years; 120 girls). Of these 80 participants were patients with migraine, 23 were patients with tension-type headache, and 69 were healthy controls. The following sensory measures were obtained: Mechanical Detection Threshold (MDT), Mechanical Pain Threshold (MPT), Mechanical Pain Sensitivity (MPS), detection and pain threshold for Transcutaneous Electrical Nerve Stimulation (TENS), olfactory and intranasal trigeminal detection threshold, and odor identification ability. Sensory sensitivity was compared between groups with a series of Kruskal-Wallis tests. Binomial regression models were used to compare the relative utility of sensory sensitivity measures in classifying participants into patients and healthy controls, as well as into patients with migraine and tension-type headache. RESULTS: Patients with migraine had lower MPT measured at the forearm than patients with tension-type headaches and healthy controls. MPS was higher in patients with migraine than in healthy controls. All patients with headaches had lower detection threshold of TENS and higher olfactory sensitivity. Healthy controls showed increased intranasal trigeminal sensitivity. Scores in MPS, TENS, and olfactory and trigeminal thresholds were significantly predicting presence of primary headaches. Additionally, scores in MPT, olfactory and trigeminal threshold were positive predictors of type of headache. CONCLUSIONS: Children with primary headaches exhibit different sensory profiles than healthy controls. The obtained results suggest presence of increased overall, multimodal sensitivity in children with primary headaches, what may negatively impact daily functioning and contribute to further pain chronification. TRIAL REGISTRATION: The study was registered in the German Registry of Clinical Trials (DRKS) DRKS00021062.

Two-Point Discrimination for Upper Extremity and Face in Healthy Young Adults: A Cross-Sectional Study.

BACKGROUND AND AIM: The threshold values of two-point discrimination (TPD) provide a numerical measure of tactile acuity. Normal reference values are needed to decide whether sensory variability is within normal sensorial limits. The study aimed to determine the upper extremity and face threshold values in healthy young adults. MATERIALS AND METHODS: Static TPD thresholds of 67 healthy young adults aged 18-35 years were assessed. Eight skin areas in the face and upper extremity on the dominant side were assessed using a "method of limits" approach with an aesthesiometer. Differences between genders were examined with the Mann-Whitney U test. The Spearman correlation analysis investigated the relationship between age and TPD measurements. RESULTS: TPD values ranged between 4.66 and 19.16 mm and 1.33-68.66 mm in the face and upper extremity, respectively, in the participants with a mean age of 23.83 ± 4.66 years. Fingertips and the area over the lateral mandibula showed the greatest sensitivity. The threshold values of TPD showed both interindividual and intraindividual variability. There was no statistical difference in the TPD values according to gender in any of the measured areas, and there was no relationship between age and TPD test values. CONCLUSIONS: The threshold values of TPD have clinical applicability in various diseases affecting the sensation of the upper extremity and/or face. These data may help the detection of early sensory loss.

A review of assessment methods for measuring individual differences in oral somatosensory perception.

While taste and smell perception have been thoroughly investigated, our understanding of oral somatosensory perception remains limited. Further, assessing and measuring individual differences in oral somatosensory perception pose notable challenges. This review aimed to evaluate the existing methods to assess oral somatosensory perception by examining and comparing the strengths and limitations of each method. The review highlighted the lack of standardized assessment methods and the various procedures within each method. Tactile sensitivity can be assessed using several methods, but each method measures different tactile dimensions. Further investigations are needed to confirm its correlation with texture sensitivity. In addition, measuring a single textural attribute may not provide an overall representation of texture sensitivity. Thermal sensitivity can be evaluated using thermal-change detection or temperature discrimination tests. The chemesthetic sensitivity tests involve either localized or whole-mouth stimulation tests. The choice of an appropriate method for assessing oral somatosensory sensitivity depends on several factors, including the specific research objectives and the target population. Each method has its unique intended purpose, strengths, and limitations, so no universally superior approach exists. To overcome some of the limitations associated with certain methods, the review offers alternative or complementary approaches that could be considered. Researchers can enhance the comprehensive assessment of oral somatosensory sensitivity by carefully selecting and potentially combining methods. In addition, a standardized protocol remains necessary for each method.

TORONTO: A trial-oriented multidimensional psychometric testing algorithm.

Bayesian adaptive methods for sensory threshold determination were conceived originally to track a single threshold. When applied to the testing of vision, they do not exploit the spatial patterns that underlie thresholds at different locations in the visual field. Exploiting these patterns has been recognized as key to further improving visual field test efficiency. We present a new approach (TORONTO) that outperforms other existing methods in terms of speed and accuracy. TORONTO generalizes the QUEST/ZEST algorithm to estimate simultaneously multiple thresholds. After each trial, without waiting for a fully determined threshold, the trial-oriented approach updates not only the location currently tested but also all other locations based on patterns in a reference data set. Since the availability of reference data can be limited, techniques are developed to overcome this limitation. TORONTO was evaluated using computer-simulated visual field tests: In the reliable condition (false positive [FP] = false negative [FN] = 3%), the median termination and root mean square error (RMSE) of TORONTO was 153 trials and 2.0 dB, twice as fast with equal accuracy as ZEST. In the FP = FN = 15% condition, TORONTO terminated in 151 trials and was 2.2 times faster than ZEST with better RMSE (2.6 vs. 3.7 dB). In the FP = FN = 30% condition, TORONTO achieved 4.2 dB RMSE in 148 trials, while all other techniques had > 6.5 dB RMSE and terminated much slower. In conclusion, TORONTO is a fast and accurate algorithm for determining multiple thresholds under a wide range of reliability and subject conditions.

Impact and visualization of scotomatic glare in central visual field perception.

Strong monochromatic point light sources such as Light Emitting Diodes (LED) or Lasers have been increasingly used in recent decades. This also raises the risk of misuse resulting in glare phenomena and associated visual impairment. The objective of this prospective and partially blinded study was the visualization and characterization of glare-induced scotomas in visual field by dazzling with monochromatic point light sources in terms of disability and discomfort glare. Automated threshold perimetry under dazzling by LED exposure at three different wavelengths (470, 530 and 625 nm) and four different intensities (25, 50, 75, and 100%) was performed in 31 healthy subjects resulting in 434 visual field examinations. Visual disability was measured by sensitivity loss in the central 30°as compared to unexposed controls and visualized by reconstruction of mean visual fields for each group via backward-calculation. Psychological glare was assessed by subsequent questionnaire and evaluated based on the de Boer rating scale of discomfort. Increasing glare intensities resulted in a significant decrease in mean sensitivity for all wavelengths tested, paralleled by an increase of discomfort glare. The loss of sensitivity was scattered over all quadrants with accentuation of the corresponding mean exposure area. Reconstructed visual fields confirmed visual impairment in all quadrants at an extent of at least 30°. We conclude that even off-axis light exposure may affect central visual field perception. Our results extend previous research on directed light interaction and contribute in explaining its incapacitating impact on human performance.

Standard models of spatial vision mispredict edge sensitivity at low spatial frequencies.

One well-established characteristic of early visual processing is the contrast sensitivity function (CSF) which describes how sensitivity varies with the spatial frequency (SF) content of the visual input. The CSF prompted the development of a now standard model of spatial vision. It represents the visual input by activity in orientation- and SF selective channels which are nonlinearly recombined to predict a perceptual decision. The standard spatial vision model has been extensively tested with sinusoidal gratings at low contrast because their narrow SF spectra isolate the underlying SF selective mechanisms. It is less studied how well these mechanisms account for sensitivity to more behaviourally relevant stimuli such as sharp edges at high contrast (i.e. object boundaries) which abound in the natural environment and have broader SF spectra. Here, we probe sensitivity to edges (2-AFC, edge localization) in the presence of broadband and narrowband noises. We use Cornsweet luminance profiles with peak frequencies at 0.5, 3 and 9 cpd as edge stimuli. To test how well mechanisms underlying sinusoidal contrast sensitivity can account for edge sensitivity, we implement a single- and a multi-scale model building upon standard spatial vision model components. Both models account for most of the data but also systematically deviate in their predictions, particularly in the presence of pink noise and for the lowest SF edge. These deviations might indicate a transition from contrast- to luminance-based detection at low SFs. Alternatively, they might point to a missing component in current spatial vision models.

A bias in transsaccadic perception of spatial frequency changes.

Visual processing differs between the foveal and peripheral visual field. These differences can lead to different appearances of objects in the periphery and the fovea, posing a challenge to perception across saccades. Differences in the appearance of visual features between the peripheral and foveal visual field may bias change discrimination across saccades. Previously it has been reported that spatial frequency (SF) appears higher in the periphery compared to the fovea (Davis et al., 1987). In this study, we investigated the visual appearance of SF before and after a saccade and the discrimination of SF changes during saccades. In addition, we tested the contributions of pre- and postsaccadic information to change discrimination performance. In the first experiment, we found no differences in the appearance of SF before and after a saccade. However, participants showed a clear bias to report SF increases. Interestingly, a 200-ms postsaccadic blank improved the precision of the responses but did not affect the bias. In the second experiment, participants showed lower thresholds for SF increases than for decreases, suggesting that the bias in the first experiment was not just a response bias. Finally, we asked participants to discriminate the SF of stimuli presented before a saccade. Thresholds in the presaccadic discrimination task were lower than in the change discrimination task, suggesting that transsaccadic change discrimination is not merely limited by presaccadic discrimination in the periphery. The change direction bias might stem from more effective masking or overwriting of the presaccadic stimulus by the postsaccadic low SF stimulus.

Novel Vibrating Foot Orthoses for Improving Tactile Sensation in Type 2 Diabetes With Peripheral Neuropathy.

Improving tactile sensation by vibrating insoles was recommended to prevent foot ulcers in diabetic peripheral neuropathy (DPN). Lack of an insole design for diabetics was a challenge. Clinical trials on applying vibrating insoles with noise and stochastic resonance (SR) stimulating tactile were also required. In this study, vibrating foot orthoses (VFO) with a total contact design based on orthotics were proposed to provide proper insoles for diabetes. This study aimed to determine if VFO were beneficial at enhancing tactile in DPN. VFO were developed in combination with individual's custom-made foot orthoses and stimulation signals-integrating random 0-100 Hz square wave pulse signals with pseudorandom white noise by a SR approach. Sixty patients with mild-to-severe DPN were randomized to conduct crossover experiments: using and without VFO for 60 minutes stimulation at 90% of individuals' vibration perception threshold (VPT) level. VPT values when using VFO at the 1st and 5th metatarsophalangeal joints of the left foot decreased by 9.35% ( [Formula: see text].001); 9.04% ( [Formula: see text].001), and of the right foot decreased by 7.63% ( [Formula: see text].001); 7.24% ( [Formula: see text].001), respectively. Without VFO, there was no significant difference. Subgroups of mild and moderate DPN tended to benefit greatly from utilizing VFO. VFO can improve tactile in DPN. VFO may contribute to restoring/prolonging tactile and protective sensations, also decreasing peripheral nervous system deterioration. VFO might be useful for neurorehabilitation, and help prevent foot ulcers and disabilities.

Effect of physical activity on olfaction acuity: A systematic review.

Olfaction acuity, which includes detection thresholds, discrimination and identification, appears to decline with age, obesity, and various neurological disorders. Knowing that smell influences energy intake, there is a growing interest in protecting this sense. Physical activity could be a key intervention to counteract the loss of olfaction. This systematic review aims to explore the literature on the effect of physical activity on olfaction acuity. The search strategy consisted of using index terms and keywords in MEDLINE, EMBASE, EBM Reviews - Cochrane Central Register of Controlled Trials, CINAHL, SPORTDiscus, and Web of Science search engine. Data from 17 trials involving 10,861 participants showed that physical activity improved olfaction thresholds, discrimination, identification and perceived intensity. Regular practice of physical activity seemed to have better effects on olfaction components than acute exercise. Although this review has clarified the evidence on the effects of physical activity on olfaction, better methodological consistency is needed.

An effective textured Novel Object Recognition Test (tNORT) for repeated measure of whisker sensitivity of rodents.

Rodents use their whisker system to discriminate surface texture. Whisker-based texture discrimination tasks are often used to investigate the mechanisms encoding tactile sensation. One such task is the textured Novel Object Recognition Test (tNORT). It takes advantage of a tendency of rodents to explore novel objects more than familiar ones and assesses the sensitivity of whiskers in discriminating different textures of objects. It requires little training of the animals and the equipment involved is a simple arena with typically two objects placed inside. The success of the test relies on rodents spending sufficient time exploring these objects. Animals may lose interests in such tasks when performed repetitively within a limited time frame. However, such repeated tests may be crucial when establishing a sensitivity threshold of the whisker system. Here we present an adapted rodent tNORT protocol designed to maintain sustained interest in the objects even with repeated testing. We constructed complex objects from three simple-shaped objects. Different textures were provided by sandpapers of varying grit sizes. To minimise olfactory clues, we used the sandy and the laminar side of the same sandpaper as the familiar and novel textures assigned at random. We subsequently conducted repeated tNORTs on eight rats in order to identify a critical threshold of the sandpaper grit size below which rats would be unable to discriminate the sandy from the laminar side. With an inter-test-interval of seven days and after five tNORTs, the protocol enabled us to successfully identify the threshold. We suggest that the proposed tNORT is a useful tool for investigating the sensitivity threshold of the whisker system of rodent, and for testing the effectiveness of an intervention by comparing sensitivity threshold pre- and post-intervention.

Validity of Computer-Controlled Skin Sensation Threshold Measurements and Relationship to Balance in Older People.

Falls are an important health issue for older people, as they lead to increased morbidity and mortality and reduced physical function, activities of daily living, and quality of life. Skin sensation is an indicator of the ability to maintain balance, which is a factor in fall risk. We investigated the validity of a computer-controlled plantar-foot sensation-testing instrument (PFS tester) that measures skin sensation. We examined the within-subject reproducibility of skin sensation thresholds and their relationship to balance in older participants. Within-subject skin sensation threshold reproducibility was examined using intraclass correlation coefficients. The skin sensation thresholds showed moderate within-subject reproducibility. The associations between skin sensation thresholds and balance were examined using multiple regression analysis. We found a significant relationship between skin sensation thresholds and balance. The results indicate that the PFS tester is clinically applicable and a reliable indicator of balance ability.

Lack of association of impaired upper airway sensation with the presence or absence of obstructive sleep apnoea or chronic rhinosinusitis in World Trade Center responders.

OBJECTIVE: Examine sensory function of the upper airway in four groups of subjects recruited from the World Trade Centre General Responder Cohort (WTCGRC), with/without obstructive sleep apnoea (OSA), and with/without chronic rhinosinusitis (CRS). METHODS: Upper airway sensory function was determined using 2-point discrimination (2-PD) and vibration threshold (VT) in 163 WTCGRC subjects with both OSA and CRS (cases), OSA or CRS alone and without OSA or CRS (controls). Presence of OSA was determined from clinical sleep studies or home sleep testing. Presence of CRS was determined by nasal symptom questionnaire. The relationship between the presence of OSA and CRS and upper airway sensory impairment was assessed using linear regression analysis with each of 2PD and VT sensory threshold values as the dependent variable; OSA, CRS and their interaction were the independent variables. Age, gender and body mass index were covariates in the statistical model. The primary analysis was comparison of OSA+CRS versus controls (no OSA and no CRS) evaluated by linear contrasts. RESULTS: There were no differences in 2-PD or VT in those with OSA+CRS, OSA and CRS alone or controls. However, both 2-PD and VT were significantly higher in the WTCGRC controls compared with values seen in historical controls using the same methodology (median 2-PD 13.0; CI (11.0 to 13.5) vs 10.5; CI (8 to 11); VT: mean±SEM (9.3±0.6 vs 2.2±0.1)). CONCLUSION: While no differences were found in upper airway sensation between cases of OSA and CRS versus controls in the WTGRC population, there was evidence of impaired upper airway sensation in the WTGRC overall.

A unified framework for perceived magnitude and discriminability of sensory stimuli.

The perception of sensory attributes is often quantified through measurements of sensitivity (the ability to detect small stimulus changes), as well as through direct judgments of appearance or intensity. Despite their ubiquity, the relationship between these two measurements remains controversial and unresolved. Here, we propose a framework in which they arise from different aspects of a common representation. Specifically, we assume that judgments of stimulus intensity (e.g., as measured through rating scales) reflect the mean value of an internal representation, and sensitivity reflects a combination of mean value and noise properties, as quantified by the statistical measure of Fisher information. Unique identification of these internal representation properties can be achieved by combining measurements of sensitivity and judgments of intensity. As a central example, we show that Weber's law of perceptual sensitivity can coexist with Stevens' power-law scaling of intensity ratings (for all exponents), when the noise amplitude increases in proportion to the representational mean. We then extend this result beyond the Weber's law range by incorporating a more general and physiology-inspired form of noise and show that the combination of noise properties and sensitivity measurements accurately predicts intensity ratings across a variety of sensory modalities and attributes. Our framework unifies two primary perceptual measurements-thresholds for sensitivity and rating scales for intensity-and provides a neural interpretation for the underlying representation.