Subjective Threshold Research Articles

Oxygen consumption and heart rate obtained in a ramp protocol are equivalent during exercise session of rectangular loading at ventilatory thresholds for athletes

Abstract Training near or at ventilatory threshold (VT) is an adequate stimulus to improve the thresholds for sedentary subjects, but a higher intensity is necessary for conditioned subjects. The choice of cardiopulmonary exercise testing (CPx) protocol has an influence on VTs identification and can reduce their reliability for exercise prescription. This study tested if VO2 and heart rate (HR) corresponding to first (VT1) and second ventilatory threshold (VT2) determined during a ramp protocol were equivalent to those observed in rectangular load exercises at the same intensity in runners elite athletes (EA) and non-athletes (NA). Eighteen health subjects were divided into two groups: EA (n = 9, VO2max 68.6 mL·kg-1·min-1) and NA (n = 9, VO2max 47.2 mL·kg-1·min-1). They performed CPx and 48h and 96h later, a continuous running lasting 1 h for VT1 and until exhaustion for VT2. The results showed that EA at VT1 session, presented delta differences for VO2 (+9.1%, p = 0.125) vs. NA (+20.5%, p = 0.012). The Bland-Altman plots for VT1 presented biases of (4.4 ± 6.9) and (5.5 ± 5.6 mLO2·kg-1·min-1) for AE and NA, respectively. In VT2, the VO2 and HR of the NA showed biases of (0.4 ± 2.9 mLO2·kg-1·min-1) and (4.9 ± 4.2 bpm). The ramp protocol used in this study was inappropriate for NA because it underestimates the values of VO2 and HR at VT1 found in the rectangular load exercise. The HR showed good agreement at VT2 with CPx and may be a good parameter for controlling exercise intensity.

Comparison of frequency-Specific hearing thresholds between pure-tone audiometry and auditory steady-state response

Introduction: Hearing assessment in difficult to assess persons gives inconsistent response in free field hearing and pure-tone audiometry (PTA). We have been performing brainstem evoked response audiometry (BERA) as an objective assessment in such cases. BERA has limitations that it is not frequency specific, measures thresholds in higher frequencies only, signal intensity levels cannot be higher than 90 dB and presents the data in waveform which needs to be interpreted by experienced audiologist to deduce correct information. All these limitations can be negated with use of auditory steady-state response (ASSR) which can present intensity levels till 120 dB, is frequency specific, even for lower frequencies and has automated response and deduction analysis. The aim of our study was to compare pure-tone thresholds with ASSR thresholds in normal hearing and hearing loss subjects with an objective to validate the ASSR as a tool for objective hearing assessment. Materials and Methods: In this prospective cross-sectional study of 70 adults (n = 140 ears) of both genders, with and without hearing complaints, Group 1 consisted of 24 individuals of normal hearing, Group 2 consisted of 25 individuals of sensorineural hearing loss, and 21 individuals with conductive hearing loss in Group 3. The patients were evaluated with PTA and ASSR test. The mean pure tone and ASSR thresholds for each frequency were calculated and analyzed using the SPSS IBM software. Results: The mean difference of ASSR with PTA was noted at 9.92 dB in the right ear and 10 dB in the left ear. A high significant correlation was noted between ASSR and PTA with P(0.0005) across all the three groups. The relationship between the PTA and ASSR measurement for measuring average hearing threshold levels is described by the equation: PTA = ASSR mean × 0.99–9.92. Conclusion: ASSR is an excellent tool to predict accurate level of frequency-specific hearing threshold. It has constant relationship with pure tone thresholds. ASSR can predict true hearing thresholds in “difficult to assess” patients such as children and malingerers. This can also be used in the prediction of disability assessment objectively.

An innovative methodology to define the bus comfort level

Abstract On-board comfort is one of the factors influencing bus users’ perceptions. Investigating on comfort levels can support transit agencies in monitoring service performance and implementing strategies to improve the service. The specific objective of this paper is to develop an innovative methodology that provides a measure of the quality level of a bus ride in terms of comfort on board, considering instantaneous values of lateral and longitudinal vehicle acceleration. This methodology is based on the matching of subjective and objective measures of comfort. More specifically, authors identify subjective thresholds from the perception of comfort on board and objective thresholds from kinematic parameters recorded along bus routes. The proposed methodology allows to identify a comfort domain and to recognise where passengers experiment comfort/discomfort conditions associated with the driving style of bus drivers.

An Alternative to the Carnegie Classifications: Identifying Similar Doctoral Institutions With Structural Equation Models and Clustering

The Carnegie Classification of Institutions of Higher Education is a commonly used framework for institutional classification that classifies doctoral-granting schools into three groups based on research productivity. Despite its wide use, the Carnegie methodology involves several shortcomings, including a lack of thorough documentation, subjectively placed thresholds between institutions, and a methodology that is not completely reproducible. We describe the methodology of the 2015 and 2018 updates to the classification and propose an alternative method of classification using the same data that relies on structural equation modeling (SEM) of latent factors rather than principal component-based indices of productivity. In contrast to the Carnegie methodology, we use SEM to obtain a single factor score for each school based on latent metrics of research productivity. Classifications are then made using a univariate model-based clustering algorithm as opposed to subjective thresholding, as is done in the Carnegie methodology. Finally, we present a Shiny web application that demonstrates sensitivity of both the Carnegie Classification and SEM-based classification of a selected university and generates a table of peer institutions in line with the stated goals of the Carnegie Classification.

Decreasing Pain Ratings in Chronic Arm Pain Through Changing a Virtual Body: Different Strategies for Different Pain Types

Modifying the visual aspect of a virtual arm that is felt as one's own using immersive virtual reality (VR) modifies pain threshold in healthy subjects, but does it modify pain ratings in chronic pain patients? Our aim was to investigate whether varying properties of a virtual arm co-located with the real arm modulated pain ratings in patients with chronic arm/hand pain because of complex regional pain syndrome (CRPS) type I (without nerve injury) or peripheral nerve injury (PNI). CRPS (n = 9) and PNI (n = 10) patients were immersed in VR and the virtual arm was shown at 4 transparency levels (transparency test) and 3 sizes (size test). We evaluated pain ratings throughout the conditions and assessed the virtual experience, finding that patients with chronic pain can achieve levels of ownership and agency over a virtual arm similar to healthy participants. All 7 conditions globally decreased pain ratings by half. Increasing transparency decreased pain in CRPS but did the opposite in PNI, whereas increasing size slightly increased pain ratings only in CRPS. We conclude that embodiment in VR can decrease pain ratings in chronic arm pain, although the type of pain determines which strategy to decrease pain is most useful. We discuss this through the interactions between body image and pain perception. Perspective“Embodiment” in VR is useful to decrease pain ratings in chronic pain patients, but the best strategy needs to be tuned to the pain etiology. This approach could potentially help patients with chronic pain and clinicians who seek alternatives to pain management for patients.

Characteristics and Potential Biomarkers of Adult Sickle Cell Patients with Chronic Pain

A paradigm shift is occurring in our understanding of pain in patients with sickle cell disease (SCD). Vaso-occlusive episodes (VOEs) are crises of acute nociceptive pain, and have long been recognized as a hallmark of SCD (Brandow et al., 2017). While patients with SCD are traditionally considered to be at “steady state” and pain free between VOEs, recent studies have shown that a significant number of adults with SCD (~30%) experience daily chronic pain (>50% of the time in the past 6 months) (Smith et al., 2008). Although the precise mechanisms underlying this evolution from acute episodic to chronic pain are not well known, some contributing factors include age, chronic inflammation, organ damage, and opioid induced hyperalgesia (Stoicea et al., 2015; Rees et al., 2010). A recent study in a mouse model of SCD showed that mast cell activation was an important contributor to neurogenic inflammation and chronic pain (Vincent et al., 2013). We previously reported that SCD patients with chronic pain were older and had higher levels of mast cell activation markers, plasma tryptase and substance P, compared to those without chronic pain (Kuei et al., 2015). Recently, nerve growth factor (NGF) has been implicated in pathogenesis of some chronic pain syndromes (osteoarthritis), and clinical trials with anti-NGF monoclonal antibodies have been shown to result in superior pain control compared to placebo, opioids and NSAIDs. Here we report the results of our extended study of the evolution of chronic pain in SCD. A total of 72 subjects (age 15-66) were enrolled: 10 in the 15-19 age group, 19 in 20-29, 21 in 30-39, and 22 in ≥ 40. Patients transfused within the past 3 months and those who had an ED visit or hospitalization within the past 2 weeks were excluded. Information on the frequency of VOEs, presence or absence of chronic pain, HU therapy, opioid use (as mg morphine equivalents within the past 6 months), other medications and routine laboratory data (CBC, retics, chemistry panel, HbF) were collected. 4 mL of EDTA blood was collected at steady state and the plasma was separated by centrifugation and kept at -80 C. Plasma tryptase, substance P, and NGF levels were assayed by ELISA using kits from Biomatik inc (catalog# EKU07922), Enzo Life Sciences (catalog# ADI-900-018), and R&D Systems (catalog# DY256), respectively. Pressure pain threshold (PPTh) was measured using a hand-held digital algometer (AlgoMed, Medoc, Israel) four times at each of the following anatomic muscle groups on the left side of the body and then averaged for analysis: masseter, trapezius, and ulna in this consecutive order. Cutaneous mechanical pain was assessed using a Von Frey monofilament on the back of the subject's left hand. A baseline of one stimulus and then two separate series of 10 repeated stimuli each were conducted. The subject was asked to rate the pain on a scale of 0 to 10 (MFB, MF1 and MF2). Overall, 34 patients had chronic pain and 38 did not; there was an age dependent increase in the frequency of chronic pain, VOE frequency, opioid use and Von Frey MF values. Similarly, QST showed significantly lower pressure pain thresholds in subjects with chronic pain at ulna and trapezius (p=0.026 and 0.024 respectively). As expected, opioid use (daily morphine equivalents) was significantly higher in the chronic pain patients (52.8 mg vs 6.94 mg, p=0.009), suggesting a correlation between opioid use and hyperalgesia. Tryptase and substance P levels were higher in chronic pain patients, though the difference did not reach statistical significance. NGF levels were significantly higher in the chronic pain group (1126 pg/ml vs 473 pg/ml, p=0.051). Our results confirm previous observations that there is an age dependent increase in the proportion of patients with chronic pain (Table 1, Fig. 1-3). The trend towards higher levels of tryptase and substance P is in support of mast cell activation and neurogenic inflammation as a contributing factor to chronic pain (Vincent et al., 2013). To our knowledge, this is the first study of NGF as a possible contributing factor to chronic pain in SCD. If confirmed in larger multi-center studies, these observations could provide a rationale for novel interventions for chronic pain in SCD, via inhibition of mast cell activation/c-kit (tyrosine kinase inhibitors) or via repurposing of existing anti-NGF monoclonal antibodies as an alternative to opioids, whose inefficacy in chronic pain is well documented. DisclosuresKutlar:Novartis: Consultancy, Honoraria, Other: Personal fees, Research Funding; Bluebird Bio: Other: DSMB Member; Sancilio: Other: DSMB Chair.

The Relationship between Minimal Residual Disease and Patient Reported Outcomes in Relapsed/Refractory Multiple Myeloma

ObjectiveWith the introduction of novel treatments for multiple myeloma, patients are now achieving deeper and sustainable clinical responses. Recent studies have demonstrated that achieving Minimal Residual Disease (MRD) negativity leads to better progression-free survival and overall survival outcomes (Lahuerta JJ, et al. J Clin Oncol 2017. 35[25]:2900-10; Munshi NC, et al. JAMA Oncol 2016. 3[1]:28-35; Landgren O, et al. Bone Marrow Transplant 2016. 51[12]:1565-1568). However, the relationship between MRD status and patient reported outcomes (PRO) has not been reported. The objective of this analysis is to evaluate whether PRO endpoints change by MRD status using data from two randomized clinical trials of daratumumab containing treatment regimens, POLLUX (Dimopoulos MA, et al. N Engl J Med 2016. 375[14]:1319-1331) and CASTOR (Palumbo A, et al. N Engl J Med 2016. 375[8]:754-766), for patients with relapsed or refractory multiple myeloma.MethodsMRD status was assessed in POLLUX at the time of suspected CR, and at 3 and 6 months post-suspected CR for responders. Similarly, in CASTOR, MRD status was assessed for patients at the time of suspected CR and at 6 months and 12 months after first dose. MRD was assessed via next generation sequencing using the clonoSEQ® assay V2.0 (Adaptive Biotechnologies, Seattle, WA) at sensitivities of 0.001%. The PRO instruments (EORTC-QLQ-C30 and EQ-5D-5L) were collected in both POLLUX and CASTOR study prior to treatment, during the treatment phase, and post-progression. EQ-5D-5L assessed general health status and included an index value and visual analog scale (VAS) score. EORTC QLQ C30 assessed health related quality of life and included five functional scales (physical, role, emotional, social and cognitive), three symptom scales (fatigue, nausea & vomiting and pain) and a global health status (GHS) scale as well as six single items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). Summary statistics (mean, standard deviation, median, min and max) by MRD status (baseline, prior to MRD negativity, MRD negativity prior to progression) were reported and for subjects who did not achieve MRD negativity (baseline, post baseline prior to progression) on a pooled sample of subjects from the two clinical trials. To interpret a meaningful change, a 5-point threshold was defined based on the EORTC guidelines for assessing quality of life in clinical trials.ResultsOverall 137 subjects in both CASTOR and POLLUX achieved MRD negativity and had PRO data available for analysis. At baseline, GHS, EQ-5D-5L VAS and index value were 62.1, 66.7, and 0.72 respectively (GHS and VAS scores closer to 100, and index value closer to 1.0 represent better health state). Mean values increased to 67.2, 70.9, and 0.75 after achieving MRD negativity. Pain scale (symptom scores closer to 0 represent less symptoms) reduced from 30.4 to 23.5 and fatigue was similar (33.8 at baseline to 31.2) when patients achieved MRD negativity. However, when we compared the five functional scales prior to and post MRD negativity, no evident differences were identified. The mean change from baseline to post-MRD-negativity in the EORTC QLQ-C30 GHS and Pain scores exceeded a 5-point threshold, reflecting a meaningful change in subject's health-related quality of life.A total of 893 subjects in the pooled data set did not achieve MRD negativity and had PRO data available for analysis (EQ-5D-5L data were not available for 3 subjects). Baseline values for these MRD positive subjects were 60.0, 65.3, and 0.71 and the mean post-baseline (pre-progression) values remained similar at 61.1, 66.0, and 0.71 for GHS, VAS, and the index value, respectively. Pain reduced from mean 33.3 to 29.4 and fatigue was similar, changing from 36.2 to 37.6.ConclusionTo our knowledge, this is the first analysis exploring the relationship between MRD status and PRO endpoints. Results from this analysis demonstrate that patients who achieve MRD negativity status show a trend in better health-related quality of life, with meaningful improvement in EORTC QLQ-C30 GHS and pain scores. These preliminary findings indicate that overall health-related quality of life and symptom domains of EORTC-QLQ-C30 and EQ-5D-5L might be sensitive to changes in MRD status, with changes in GHS and Pain exceeding meaningful threshold for subjects. DisclosuresAvet-Loiseau:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees. He:Janssen global services: Employment. Gries:Janssen Research & Development, LLC: Employment. Pei:Janssen Research & Development, LLC: Employment. Saha:Janssen Research & Development, LLC: Employment. Chiu:Janssen Research & Development, LLC: Employment. Cote:Janssen Research & Development, LLC: Employment. Lam:Janssen Global Services, LLC: Employment.

Automated instrument designed to determine visual photosensitivity thresholds.

The Ocular Photosensitivity Analyzer (OPA), a new automated instrument to quantify the visual photosensitivity thresholds (VPT) in healthy and light sensitive subjects, is described. The OPA generates light stimuli of varying intensities utilizing unequal ascending and descending steps to yield the VPT. The performance of the OPA was evaluated in healthy subjects, as well as light sensitive subjects with achromatopsia or traumatic brain injury (TBI). VPT in healthy, achromatopsia, and TBI subjects were 3.2 ± 0.6 log lux, 0.5 ± 0.5 log lux, and 0.4 ± 0.6 log lux, respectively. Light sensitive subjects manifested significantly lower VPT compared to healthy subjects. Longitudinal analysis revealed that the OPA reliably measured VPT in healthy subjects.

Everything is illuminated: Prismatic adaptation lowers visual detection threshold in normal subjects.

Prismatic adaptation (PA) results from repeated ballistic movements of the dominant arm toward visual targets while wearing prisms shifting the visual field laterally (visuomotor prismatic training [VPT]). Following PA, subjects' pointing movements are deviated contralaterally to prismatic shift (aftereffect). The question of whether spatial attention is also biased in the same direction remains controversial in the scientific literature. To investigate the effect of PA on spatial attention, we asked healthy participants to perform a visual detection threshold task before and after VPT with left- and right-deviating prisms and visuomotor training without prisms. Our results demonstrate that both left and right VPTs modulate visual detection threshold, significantly ameliorating detection accuracy and response times bilaterally. These data indicate that PA modulates visual attention bilaterally and that detection threshold paradigms are sensitive to its effects in the visual domain. We suggest that the described PA effects are mediated by the joint action of attentional and alerting mechanisms. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

THE IMMEDIATE EFFECTS OF FOOT MASSAGE WITH COCONUT SHELL ON PRESSURE PAIN THRESHOLD AND FOOT GRIP STRENGTH IN HEALTHY SUBJECTS: A PILOT STUDY

Feet are very important parts of the body because they carry almost all of the body weight and contribute to human locomotion. Daily works in prolonged standing position may cause foot pain and fatigue easily. Currently, foot massage with coconut shells has been practiced in some eastern countries to relieve foot pain and fatigue for a long time without sufficient scientific evidence. This study aimed to preliminarily determine the immediate effects of a foot massage with coconut shell on pressure pain threshold and foot grip strength in healthy subjects. Thirteen healthy volunteers, who worked in standing position mostly, participated in the study and received a 5-minute session of foot massage using coconut shells. Pressure pain threshold and foot grip strength were measured before and 2 minutes after the foot massage. The results showed that foot massage with coconut shells could increase pressure pain threshold and foot grip strength significantly (P<0.05). We suggested that foot massage with coconut shells may raise pressure pain threshold of the feet and provide better effort on foot muscles contraction. Further study with a randomized controlled trial was recommended to verify these effects.

A Bayesian approach to mapping the uncertainties of global urban lands

Global distribution of urban lands is one of the essential pieces of information necessary for urban planning. However, large disagreement exists among different products and the uncertainty remains difficult to quantify. We applied a Bayesian approach to map the uncertainties of global urban lands. We demonstrated the approach by producing a hybrid global urban land map that synthesized five different urban land maps in ca. 2000 at 1-km resolution. The resulting hybrid map is a posterior probability map with pixel values suggesting the probability of being urban land, which is validated by 30-m higher resolution references. We also quantified the minimum and maximum urban areas in 2000 for each country/continent based on subjective probability thresholds (i.e., 0.9 and 0.1) on our hybrid urban map. Globally, we estimated that the urban land area was between 377,000 and 533,000 km2 in 2000. The credible interval of minimum/maximum urban area can help guide future studies in estimating urban areas. In addition to providing uncertainty information, the hybrid map also achieves higher accuracy than individual maps when it is converted into a binary urban/non-urban map using a probability threshold of 0.5. This new method has the ability to further integrate discrete site/location-based data, local, regional, and global urban land maps. As more data is sequentially integrated, the accuracy is expected to improve. Therefore, our hybrid map should not be regarded as a final product, but a new prior product for future synthesis and integration toward a “big data” solution.

A Sensitive Thresholding Method for Confocal Laser Scanning Microscope Image Stacks of Microbial Biofilms.

Biofilms are surface-attached microbial communities whose architecture can be captured with confocal microscopy. Manual or automatic thresholding of acquired images is often needed to help distinguish biofilm biomass from background noise. However, manual thresholding is subjective and current automatic thresholding methods can lead to loss of meaningful data. Here, we describe an automatic thresholding method designed for confocal fluorescent signal, termed the biovolume elasticity method (BEM). We evaluated BEM using confocal image stacks of oral biofilms grown in pooled human saliva. Image stacks were thresholded manually and automatically with three different methods; Otsu, iterative selection (IS), and BEM. Effects on biovolume, surface area, and number of objects detected indicated that the BEM was the least aggressive at removing signal, and provided the greatest visual and quantitative acuity of single cells. Thus, thresholding with BEM offers a sensitive, automatic, and tunable method to maintain biofilm architectural properties for subsequent analysis.

Sensory-specific impairment among older people. An investigation using both sensory thresholds and subjective measures across the five senses.

Age-related sensory impairment is a slow and gradual progress, which affects multiple modalities. Two contradictory hypotheses exist about the age-related decline of sensory thresholds. The common factor theory assumes one underlying factor—which accounts for the loss of several sensory modalities simultaneously—and the specific factor theory predicts that the sensory decline is uncorrelated between different modalities. In this study, we aimed to explore whether (i) there is a common factor of sensory thresholds in older people, (ii) older people assume that sensory decline in one modality also affects other modalities, (iii) there is a relation between sensory threshold and the subjective assessment of sensory function. This was accomplished by collecting both threshold measures and self-reported ratings for smell, hearing, taste, vision, and touch function in a group of 104 older people (mean age: 67.2 years; SD: 9.85; range: 50–100 years). Results indicated that there was no common factor of sensory thresholds, hence an impairment in one modality did not necessarily imply a shortfall in other modalities. In contrast, our results suggested one or two common factor(s) for the participants’ ratings. Participants who reported a diminished function in one sense tended to generalize this rating to the other senses as well. The correspondence between subjective ratings and sensory thresholds was relatively good for vision and audition, although no correlations were observed for the other domains. These findings have implications for clinicians, suggesting that subjective measures should be combined with sensory threshold measurements when evaluating sensory dysfunction. Also, these data convey a positive message for older people and their physicians by showing that loss in one sensory modality does not necessarily generalize to losses across all sensory modalities.

RETRACTED ARTICLE: Gray relational clustering model for intelligent guided monitoring horizontal wells

When drilling CBM horizontal wells, in order to improve the drilling rate of coal seams, real-time monitoring the lithology encountered underground must be performed. There are a large number of real-time logging data and historical data during the drilling process. Through data mining methods, the relationship between the changes of the underground lithology and the logging data can be found. Therefore, an improved gray clustering algorithm combined with the principle of mechanical specific energy is proposed to form a set of gray clustering model that can realize intelligent guided monitoring horizontal wells. By introducing correlation degree analysis method, this model optimizes the original gray fixed weight clustering monitoring model, establishing a horizontal well-oriented gray-related clustering model. In addition, the concept of decision rough set is used to replace the subjective given clustering threshold for the cluster threshold problem to achieve rapidly monitoring the CBM horizontal well drilling process. Through field data optimization analysis, the results show that the improved gray correlation clustering model can quickly and accurately identify lithology through real-time logging data.

Attenuation of ultrasonic noise in the 10-16 kHz frequency range by earplugs

The aim of the study was to determine attenuation of earplugs for ultrasonic noise in the frequency range of 10-16 kHz. The attenuation of earplugs in 1/3-octave-bands with the centre frequencies of 10 kHz, 12.5 kHz, and 16 kHz using the REAT (real-ear attenuation at threshold) method based on the measurements of hearing threshold of subjects. The study was carried out for 29 models of earplugs commonly used in the industry designed by various manufacturers, including 13 models of foam earplugs, 10 models of flanged earplugs, 5 models of headband earplugs and one model of no-roll earplugs. The values of the measured attenuation of earplugs are in the range 12.9-33.2 dB for the 10 kHz frequency band, 22.8-35.2 dB for the 12.5 kHz frequency band and 29.5-37.2 dB for the 16 kHz frequency band. The attenuation of earplugs in the frequency range 10-16 kHz has higher values (statistically significant changes) for foam earplugs than flanged earplugs (p = 0.0003 vs. p = 0.0006) or headband earplugs (p = 0.0002 vs. p = 0.04). The tests indicated that there is no uniform relation between the sound attenuation in the frequencies range of 10-16 kH and the catalogue H parameter (high-frequency attenuation value) of earplugs. Therefore, it is not possible to easily predict the attenuation of ultrasonic noise in the frequency range of 10-16 kHz using the sound attenuation data for the normally considered frequency range (up to 8 kHz). Med Pr 2018;69(4):395-402.

Vestibular Deficits with Type 2 Diabetes Assayed by Motion Perception Thresholds

Postural control depends on the coordinated action of many physiologic systems, and sensory feedback about body motion plays a critical role. Individuals with diabetes have increased postural sway and risk of falling. Many studies have implicated somatosensory neuropathy, but a vestibular role has also been suggested. To further explore vestibular deficits, we measured vestibular perceptual thresholds in subjects with type 2 diabetes. These thresholds quantify the smallest motion that an individual can reliably sense. We selected this approach because thresholds are sensitive to pathology, age and balance test performance. We tested four human subjects (ages 52-69, one female) who received a diagnosis of type 2 diabetes between 12 and 17 years before testing. Subjects were not screened for neuropathy or blood sugar control (HbA1c: 6.8, 9.1, 13 and 7.6). Thresholds were tested with the subject sitting in a chair on a moving platform with the head held firmly by a helmet. The platform repeatedly exposed subjects to small motions and subjects reported their perception (“press the button in your left hand if you thought you moved to the left and the button in your right hand if you thought you moved to the right.”) Motion amplitudes were adaptively adjusted to find the stimulus amplitude at which subjects were about 80% correct. Five motion conditions were tested. Subjects with diabetes had higher thresholds than published normative data (repeated-measures ANOVA, p=0.0059): +36% for yaw rotation, +15% for lateral translation, +220% for vertical translation, +13% for roll tilt (1 s motions), +3% for roll tilt (5 s motions). These results emphasize the need for further studies on the effects of diabetes on the vestibular system. Disclosure S. King: None. D.J. Wexler: None. T. Leeder: None. F. Karmali: Employee; Spouse/Partner; Biogen.

Subjective decision threshold for accurate visual detection performance in rats

The dissociation between a subjective-criterion performance and forced performance in a sensory detection can provide critical insights into the neural correlates of sensory awareness. Here, we established a behavioral task for rats to test their spatial-visual cue detection ability, using a two alternative choice task with and without a third choice option where animals get rewards only in the objective absence of a visual cue. In the trials without the third option, spatial choice accuracy decreased from near perfect to near chance levels as the visual cue brightness decreased. In contrast, with the third option, the rats exhibited >90% spatial choice accuracy regardless of the cue brightness. The rats chose the third choice option less frequently when the cue was brighter, suggesting that rats have a generalized strategy to make spatial choices only when their internal detection criterion is met. Interestingly, even when the animals chose the third option, they could still significantly and correctly choose the direction of the visual stimuli if they were forced. Our data suggest that the rats’ variable detection performance with identical set of stimuli is derived from stochastic processing of visual signals with a certain internal detection threshold rather than general motivational threshold.

AUDIOMETRIC THRESHOLD MEASUREMENT IN CHILDREN WITH INTELLECTUAL DISABILITY: PREFERRED RESPONSE MODE

Background The accuracy of pure tone audiometry is important for the success of auditory assessments and in monitoring rehabilitation programs for auditory disorders. Studies have reported that pushing a button as a response mode has a significant effect on pure tone thresholds in subjects with normal and impaired hearing. We therefore assumed that a push-button response mode may negatively impact pure tone threshold measurement in subjects with intellectual disability (ID) owing to their impaired cognition and poor motor coordination. The current study compares in persons with ID the number of presentations, number of false alarms, test duration, and participant preference across three response modes during audiometry. Material and Methods Air-conduction thresholds were measured for each response mode – push button, hand raise, and verbal – at octave intervals between 500 and 2000 Hz in the right ear of 14 children with intellectual disability. The order of the response mode was randomly assigned to three subgroups. Results The results indicated that among ID subjects a verbal response yielded a threshold in significantly less time. There was a significant preference for using the verbal response. Children who were assigned a push button or hand raise also responded with a verbal response. For push button participants, this occurred before the button was pushed and for the hand raising participants, a verbal response occurred before the button push. Conclusions The study finds verbal responses more beneficial in measuring auditory thresholds in children with ID.

Investigation of drivers’ thresholds of a subjectively accepted driving performance with a focus on automated driving

Lately, the development and implementation of automated driving moved to the center of interest in the automotive industry. In this context, one of the central issues – the configuration of adequate trajectories – is mainly tackled using a technical approach. However, it appears that a technically ideal driving performance does not necessarily coincide with the drivers’ subjective preferences. This study strives to determine thresholds of a subjectively accepted driving performance regarding lateral vehicle control. A second objective is to analyze the influence of selected personal and situational factors on these thresholds. An empirical online survey with 161 participants rating video sequences of driving performances was conducted. The video sequences differed not only with regard to the lateral offset of the ego-vehicle but also concerning the weather (sun/rain) and traffic conditions (existence/driving behavior of oncoming traffic). Additionally, the participants’ driving experience and sensation seeking were considered in the data evaluation. To analyze the data, binary logistic regression analyses were calculated. They revealed that the subjective evaluation of driving performances varies primarily depending on the lateral offset of both the ego-vehicle and the oncoming traffic. The results indicate that regarding the lateral offset certain thresholds of subjectively accepted driving performances do exist. Regarding the development of automated driving systems, two issues need to be considered in order to ultimately guarantee user acceptance. First, the subjective thresholds need to be integrated into the systems’ trajectory planning. Second, the oncoming traffic’s driving behavior has to be considered.

The Sensitivity of Thresholds by Ground Reaction Force and Postural Stability in Subjects With and Without Navicular Drop

Understanding plantar pressure changes is an important component of the functional evaluation of subjects with flat foot. However, the altered postural control determined by the threshold from the vertical ground reaction force (GRF) requires clarification. The purpose of our study was to investigate the various GRF thresholds in subjects with and without flat foot during 1-leg standing. We included 34 control subjects and 30 subjects with flat foot in the present study. They performed the 1-leg standing test for 30 seconds, with the contralateral hip and knee flexed approximately 90°. The sensitivity of the various GRF thresholds (3, 7, 15, 50, and 100 N) for the postural stability index was analyzed with and without visual input. The standing times for the control and flat foot groups were 23.76 ± 4.42 and 21.78 ± 6.59 seconds, respectively, with no significant differences (t = 1.23; p = .22). The 2 groups demonstrated a significant interaction between the visual condition and the threshold levels (F = 11.40; p = .001). The postural stability index was significantly different in the eyes-open condition (0.95 ± 0.08 for the control group versus 0.84 ± 0.23 for the flat foot group; t = 2.29; p = .02). However, no difference was found in the eyes-closed condition (0.94 ± 0.10 for the control group versus 0.81 ± 0.30 for the flat foot group; t = 1.45; p = .15). These results indicate that GRF thresholds less than the 15N setting are sensitive to detect postural stability between groups, especially in the eyes-open condition. The GRF threshold setting, in addition to the visual condition, could alter the outcomes of sensitive plantar pressure changes in subjects with flat foot.