Suprathreshold Measures Research Articles

Associations between Sweet Taste Sensitivity and Polymorphisms (SNPs) in the TAS1R2 and TAS1R3 Genes, Gender, PROP Taster Status, and Density of Fungiform Papillae in a Genetically Homogeneous Sardinian Cohort.

Individual differences in sweet taste sensitivity can affect dietary preferences as well as nutritional status. Despite the lack of consensus, it is believed that sweet taste is impacted by genetic and environmental variables. Here we determined the effect of well-established factors influencing the general taste variability, such as gender and fungiform papillae density, specific genetic variants (SNPs of TAS1R2 and TAS1R3 receptors genes), and non-specific genetic factors (PROP phenotype and genotype), on the threshold and suprathreshold sweet taste sensitivity. Suprathreshold measurements showed that the sweet taste response increased in a dose-dependent manner, and this was related to PROP phenotype, gender, rs35874116 SNP in the TAS1R2 gene, and rs307355 SNP in the TAS1R3 gene. The threshold values and density of fungiform papillae exhibited a strong correlation, and both varied according to PROP phenotype. Our data confirm the role of PROP taste status in the sweet perception related to fungiform papilla density, show a higher sweet sensitivity in females who had lower BMI than males, and demonstrate for the first time the involvement of the rs35874116 SNP of TAS1R2 in the sweet taste sensitivity of normal weight subjects with body mass index (BMI) ranging from 20.2 to 24.8 kg/m2. These results may have an important impact on nutrition and health mostly in subjects with low taste ability for sweets and thus with high vulnerability to developing obesity or metabolic disease.

Suprathreshold Auditory Measures for Detecting Early-Stage Noise-Induced Hearing Loss in Young Adults.

Over 1 billion young adults are at risk for developing noise-induced hearing loss (NIHL) due to their habit of listening to music at loud levels. The gold standard for detecting NIHL is the audiometric notch around 3,000 to 6,000 Hz observed in pure tone audiogram. However, recent studies suggested that suprathreshold auditory measures might be more sensitive to detect early-stage NIHL in young adults. The present study compared suprathreshold measures in individuals with high and low noise exposure backgrounds (NEBs). We hypothesized that individuals with high NEB would exhibit reduced performance on suprathreshold measures than those with low NEB. An initial sample of 100 English-speaking healthy adults (18-35 years; females = 70) was obtained from five university classes. We identified 15 participants with the lowest NEB scores (10 females) and 15 participants with the highest NEB scores (10 females). We selected a sample of healthy young adults with no history of middle ear infection, and those in the low NEB group were selected with no history of impulse noise exposure. The study included conventional audiometry, extended high-frequency audiometry, middle ear muscle reflex (MEMR) thresholds, distortion-product otoacoustic emissions (DPOAEs), QuickSIN, and suprathreshold auditory brainstem response (ABR) measures. We used independent sample t-tests, correlation coefficients, and linear mixed model analysis to compare the audiometric measures between the NEB groups. The prevalence of audiometric notch was low in the study sample, even for individuals with high NEB. We found that: (1) individuals with high NEB revealed significantly reduced QuickSIN performance than those with low NEB; (2) music exposure via earphone revealed a significant association with QuickSIN; (3) individuals with high NEB revealed significantly reduced DPOAEs and ABR wave I amplitude compared with individuals with low NEB; (4) MEMR and ABR latency measures showed a modest association with NEB; and (5) audiometric thresholds across the frequency range did not show statistically significant association with NEB. Our results suggest that young adults with high NEB might exhibit impaired peripheral neural coding deficits leading to reduced speech-in-noise (SIN) performance despite clinically normal hearing thresholds. SIN measures might be more sensitive than audiometric notch for detecting early-stage NIHL in young adults.

Running activity, preparation and participation in marathon runs by amateurs between the age of 42-51 – a case study

Aim. In the research, we looked for the relationship between the level of training activity and aerobic capacity as well as the result in the marathon run by an amateur aged 42-51. Materials and Methods. A progressive test was used to determine the threshold speed and load of the training activity. A 10- year period was analysed among amateur runners between the age of 42 and 51. The annual and DSP (Direct Start Preparation) training activity loads were determined. The strength of the relationship between the applied load of training activity and the result in the marathon was assessed, as well as the effectiveness of forecasting the result in the marathon. Results. An average annual volume over 2,500 km (194 hours) was found. During the DSP period, there was definitely an increase in workload. On average, in the DSP, the sub-threshold, threshold and supra-threshold measures constituted 65.7%- 19.4%-14.9%, respectively. A strong correlation was found between the result in the marathon and the annual volume, as well as the supra-threshold measures. Conclusions. The examined person presented a high level of activity, which allowed to maintain a high and stable level in the marathon and a high level of efficiency expressed by the VO2max indicator. The high assessment of the progressive test in estimating the result in the marathon was confirmed.

Ion-channel degeneracy: Multiple ion channels heterogeneously regulate intrinsic physiology of rat hippocampal granule cells.

Degeneracy, the ability of multiple structural components to elicit the same characteristic functional properties, constitutes an elegant mechanism for achieving biological robustness. In this study, we sought electrophysiological signatures for the expression of ion‐channel degeneracy in the emergence of intrinsic properties of rat hippocampal granule cells. We measured the impact of four different ion‐channel subtypes—hyperpolarization‐activated cyclic‐nucleotide‐gated (HCN), barium‐sensitive inward rectifier potassium (Kir), tertiapin‐Q‐sensitive inward rectifier potassium, and persistent sodium (NaP) channels—on 21 functional measurements employing pharmacological agents, and report electrophysiological data on two characteristic signatures for the expression of ion‐channel degeneracy in granule cells. First, the blockade of a specific ion‐channel subtype altered several, but not all, functional measurements. Furthermore, any given functional measurement was altered by the blockade of many, but not all, ion‐channel subtypes. Second, the impact of blocking each ion‐channel subtype manifested neuron‐to‐neuron variability in the quantum of changes in the electrophysiological measurements. Specifically, we found that blocking HCN or Ba‐sensitive Kir channels enhanced action potential firing rate, but blockade of NaP channels reduced firing rate of granule cells. Subthreshold measures of granule cell intrinsic excitability (input resistance, temporal summation, and impedance amplitude) were enhanced by blockade of HCN or Ba‐sensitive Kir channels, but were not significantly altered by NaP channel blockade. We confirmed that the HCN and Ba‐sensitive Kir channels independently altered sub‐ and suprathreshold properties of granule cells through sequential application of pharmacological agents that blocked these channels. Finally, we found that none of the sub‐ or suprathreshold measurements of granule cells were significantly altered upon treatment with tertiapin‐Q. Together, the heterogeneous many‐to‐many mapping between ion channels and single‐neuron intrinsic properties emphasizes the need to account for ion‐channel degeneracy in cellular‐ and network‐scale physiology.

Speech comprehension across multiple CI processor generations: Scene dependent signal processing.

ObjectivesIn clinical practice, characterization of speech comprehension for cochlear implant (CI) patients is typically administered by a set of suprathreshold measurements in quiet and in noise. This study investigates speech comprehension of the three most recent cochlear implant sound processors; CP810, CP910, and CP1000 (Cochlear Limited). To compare sound processor performance across generations and input dynamic range changes, the state‐of‐the art signal processing technologies available in each sound processor were enabled. Outcomes will be assessed across a range of stimulation intensities, and finally analyzed with respect to normal hearing listeners.MethodsIn a prospective study, 20 experienced postlingually deafened CI patients who received a Nucleus CI in the ENT department of the University Hospital of SH in Kiel were recruited. Speech comprehension was measured in quiet at 40, 50, and 65 dBSPL with monosyllabic words as well as by speech reception threshold for two‐digit numbers. In noise, speech reception thresholds were measured with the adaptive German matrix test with speech and noise in front.ResultsWe found that high levels of open‐set speech comprehension are achieved at suprathreshold presentation levels in quiet. However, results at lower test levels have remained mostly unchanged for tested sound processors with default dynamic range. Expanding the lower limit of the acoustic input dynamic range yields better speech comprehension at lower presentation levels. In noise the application of ForwardFocus improves the speech reception. Overall, a continuous improvement for speech perception across three generations of CI sound processors was found.ConclusionsFindings motivate further development of signal pre‐processing, an additional focus of clinical work on lower stimulation levels, and automation of ForwardFocus.Level of evidence2.

Psychometric Characteristics of Spanish Monosyllabic, Bisyllabic, and Trisyllabic Words for Use in Word-Recognition Protocols

English materials for speech audiometry are well established. In Spanish, speech-recognition materials are not standardized with monosyllables, bisyllables, and trisyllables used in word-recognition protocols. This study aimed to establish the psychometric characteristics of common Spanish monosyllabic, bisyllabic, and trisyllabic words for potential use in word-recognition procedures. Prospective descriptive study. Eighteen adult Puerto Ricans (M = 25.6 years) with normal hearing [M = 7.8-dB hearing level (HL) pure-tone average] were recruited for two experiments. A digital recording of 575 Spanish words was created (139 monosyllables, 359 bisyllables, and 77 trisyllables), incorporating materials from a variety of Spanish word-recognition lists. Experiment 1 (n = 6) used 25 randomly selected words from each of the three syllabic categories to estimate the presentation level ranges needed to obtain recognition performances over the 10 to 90% range. In Experiment 2 (n = 12) the 575 words were presented over five 1-hour sessions using presentation levels from 0- to 30-dB HL in 5-dB steps (monosyllables), 0- to 25-dB HL in 5-dB steps (bisyllables), and -3- to 17-dB HL in 4-dB steps (trisyllables). The presentation order of both the words and the presentation levels were randomized for each listener. The functions for each listener and each word were fit with polynomial equations from which the 50% points and slopes at the 50% point were calculated. The mean 50% points and slopes at 50% were 8.9-dB HL, 4.0%/dB (monosyllables), 6.9-dB HL, 5.1%/dB (bisyllables), and 1.4-dB HL, 6.3%/dB (trisyllables). The Kruskal-Wallis test with Mann-Whitney U post-hoc analysis indicated that the mean 50% points and slopes at the 50% points of the individual word functions were significantly different among the syllabic categories. Although significant differences were observed among the syllabic categories, substantial overlap was noted in the individual word functions, indicating that the psychometric characteristics of the words were not dictated exclusively by the syllabic number. Influences associated with word difficulty, word familiarity, singular and plural form words, phonetic stress patterns, and gender word patterns also were evaluated. The main finding was the direct relation between the number of syllables in a word and word-recognition performance. In general, words with more syllables were more easily recognized; there were, however, exceptions. The current data from young adults with normal hearing established the psychometric characteristics of the 575 Spanish words on which the formulation of word lists for both threshold and suprathreshold measures of word-recognition abilities in quiet and in noise and other word-recognition protocols can be based.

Olfaction and quality of life in patients with nasal septal deviation treated with septoplasty.

Patients with septal deviation-induced nasal obstruction may experience olfactory impairment. This study aimed to evaluate septoplasty-related changes in olfactory function and their effect on patients' quality of life (QoL). Prospective study of sixty patients with nasal obstruction and septal deviation and 25 healthy controls. Objective measurements were performed for the evaluation of nasal patency and "Sniffin' sticks" tests were used for quantitative assessment of lateralized and bilateral olfactory performance. All participants self-assessed their smell using a visual analog scale and completed validated questionnaires for nasal obstruction (Nasal Obstruction Symptom Evaluation: NOSE), for nasal symptoms QoL (SinoNasal Outcome Test-22: SNOT-22), for olfaction-associated QoL (Questionnaire of Olfactory Deficits: QOD) preoperatively and six months after septoplasty and reported personal benefit after surgery (Glasgow Benefit Inventory: GBI), six months postoperatively. Smell was significantly compromised due to septal deviation especially in the more obstructed nasal cavity side. Smell improved significantly after septoplasty (subjective report and olfactory measurements), along with increased nasal patency. Increased nasal cavity volume was significantly correlated with olfactory thresholds but not with suprathreshold measurements. Subjective hyposmia and lateralized olfaction were significantly reduced postoperatively. Postoperatively, normosmic patients reported higher personal benefit from surgery than patients with olfactory disorders. The patients' QoL improved significantly, but it remained lower than the controls' group. Olfaction-associated QoL was not significantly different between patients and controls before and after septoplasty. Septoplasty leads to improvement in smell perception, and patients with improved smell report greater personal benefit from septoplasty than patients with remaining olfactory deficits.

Auditory brainstem stimulation with a conformable microfabricated array elicits responses with tonotopically organized components

Auditory brainstem implants (ABIs) restore hearing to deaf individuals not eligible for cochlear implants. Speech comprehension in ABI users is generally poor compared to that of cochlear implant users, and side effects are common. The poor performance may result from activating broad areas and multiple neuronal populations of the cochlear nucleus, however detailed studies of the responses to surface stimulation of the cochlear nucleus are lacking. A conformable electrode array was microfabricated to fit on the rat's dorsal cochlear nucleus (DCN). It hosts 20 small electrodes (each 100 μm diam.). The array was tested by recording evoked potentials and neural activity along the tonotopic axis of the inferior colliculus (IC). Almost all bipolar electrode pairs elicited responses, in some cases with an even, or relatively constant, pattern of thresholds and supra-threshold measures along the long axis of the array. This pattern suggests that conformable arrays can provide relatively constant excitation along the surface of the DCN and thus might decrease the ABI side effects caused by spread of high current to adjacent structures. We also examined tonotopic patterns of the IC responses. Compared to sound-evoked responses, electrically-evoked response mappings had less tonotopic organization and were broader in width. They became more tonotopic when the evoked activity common to all electrodes and the late phase of response were subtracted out, perhaps because the remaining activity is from tonotopically organized principal cells of the DCN. Responses became less tonotopic when inter-electrode distance was increased from 400 μm to 800 μm but were relatively unaffected by changing to monopolar stimulation. The results illustrate the challenges of using a surface array to present tonotopic cues and improve speech comprehension in humans who use the ABI.

Reliability of Measures Intended to Assess Threshold-Independent Hearing Disorders.

Recent animal studies have shown that noise exposure can cause cochlear synaptopathy without permanent threshold shift. Because the noise exposure preferentially damaged auditory nerve fibers that processed suprathreshold sounds (low-spontaneous rate fibers), it has been suggested that synaptopathy may underlie suprathreshold hearing deficits in humans. Recently, several researchers have suggested measures to identify the pathology or pathologies underlying suprathreshold hearing deficits in humans based on results from animal studies; however, the reliability of some of these measures have not been assessed. The purpose of this study was to assess the test-retest reliability of measures that may have the potential to relate suprathreshold hearing deficits to site(s)-of-lesion along the peripheral auditory system in humans. Adults with audiometric normal hearing were tested on a battery of behavioral and physiologic measures that included (1) thresholds in quiet (TIQ), (2) thresholds in noise (TIN), (3) frequency-modulation detection threshold (FMDT), (4) word recognition in four listening conditions, (5) distortion-product otoacoustic emissions (DPOAE), (6) middle ear muscle reflex (MEMR), (7) tone burst-elicited auditory brainstem response (tbABR), and (8) speech-evoked ABR (sABR). Data collection for each measure was repeated over two visits separated by at least one week. The residuals of the correlation between the suprathreshold measures and TIQ serve as functional and quantitative proxies for threshold-independent hearing disorders because they represent the portion of the raw measures that is not dependent on TIQ. Reliability of the residual measures was assessed using intraclass correlation (ICC). Reliability for the residual measures was good (ICC ≥ 0.75) for FMDT, DPOAEs, and MEMR. Residual measures showing moderate reliability (0.5 ≤ ICC < 0.75) were tbABR wave I amplitude, TIN, and word recognition in quiet, noise, and time-compressed speech with reverberation. Wave V of the tbABR, waves of the sABR, and recognition of time-compressed words had poor test-retest reliability (ICC < 0.5). Reliability of residual measures was mixed, suggesting that care should be taken when selecting measures for diagnostic tests of threshold-independent hearing disorders. Quantifying hidden hearing loss as the variance in suprathreshold measures of auditory function that is not due to TIQ may provide a reliable estimate of threshold-independent hearing disorders in humans.

Relationship Between Subjective Reports of Temporary Threshold Shift and the Prevalence of Hearing Problems in Military Personnel.

Traditional hearing conservation programs are based on the premise that noise dose, as measured by the time-weighted average noise level, is the primary risk factor associated with occupational hearing loss and that permanent threshold shifts are the most relevant outcome measures for determining when a noise-related hearing loss has occurred. However, recent studies in animal models have suggested that significant neurological damage to the hearing system can occur from noise exposures even when they are not severe enough to result in permanent threshold shifts. This has led to a number of studies attempting to relate subjective measures of noise exposure to subjective measures of hearing difficulty and suprathreshold measures of hearing performance (e.g., speech-in-noise tests). In this study, 3,330 U.S. service members volunteered to complete a survey on noise exposure, subjective hearing complaints, and tinnitus in conjunction with their annual hearing tests. Two questions were also included about the frequency and duration of temporary hearing losses that may have been experienced by the service member. The results show that subjective reports of temporary threshold shifts were substantially more predictive of tinnitus and other hearing complaints than more traditional questions based on the frequency of noise exposure.

Using Thresholds in Noise to Identify Hidden Hearing Loss in Humans.

Recent animal studies suggest that noise-induced synaptopathy may underlie a phenomenon that has been labeled hidden hearing loss (HHL). Noise exposure preferentially damages low spontaneous-rate auditory nerve fibers, which are involved in the processing of moderate- to high-level sounds and are more resistant to masking by background noise. Therefore, the effect of synaptopathy may be more evident in suprathreshold measures of auditory function, especially in the presence of background noise. The purpose of this study was to develop a statistical model for estimating HHL in humans using thresholds in noise as the outcome variable and measures that reflect the integrity of sites along the auditory pathway as explanatory variables. Our working hypothesis is that HHL is evident in the portion of the variance observed in thresholds in noise that is not dependent on thresholds in quiet, because this residual variance retains statistical dependence on other measures of suprathreshold function. Study participants included 13 adults with normal hearing (≤15 dB HL) and 20 adults with normal hearing at 1 kHz and sensorineural hearing loss at 4 kHz (>15 dB HL). Thresholds in noise were measured, and the residual of the correlation between thresholds in noise and thresholds in quiet, which we refer to as thresholds-in-noise residual, was used as the outcome measure for the model. Explanatory measures were as follows: (1) auditory brainstem response (ABR) waves I and V amplitudes; (2) electrocochleographic action potential and summating potential amplitudes; (3) distortion product otoacoustic emissions level; and (4) categorical loudness scaling. All measurements were made at two frequencies (1 and 4 kHz). ABR and electrocochleographic measurements were made at 80 and 100 dB peak equivalent sound pressure level, while wider ranges of levels were tested during distortion product otoacoustic emission and categorical loudness scaling measurements. A model relating the thresholds-in-noise residual and the explanatory measures was created using multiple linear regression analysis. Predictions of thresholds-in-noise residual using the model accounted for 61% (p < 0.01) and 48% (p < 0.01) of the variance in the measured thresholds-in-noise residual at 1 and 4 kHz, respectively. Measures of thresholds in noise, the summating potential to action potential ratio, and ABR waves I and V amplitudes may be useful for the prediction of HHL in humans. With further development, our approach of quantifying HHL by the variance that remains in suprathreshold measures of auditory function after removing the variance due to thresholds in quiet, together with our statistical modeling, may provide a quantifiable and verifiable estimate of HHL in humans with normal hearing and with hearing loss. The current results are consistent with the view that inner hair cell and auditory nerve pathology may underlie suprathreshold auditory performance.

Segmental and Suprasegmental Perception in Children Using Hearing Aids.

Suprasegmental perception (perception of stress, intonation, "how something is said" and "who says it") and segmental speech perception (perception of individual phonemes or perception of "what is said") are perceptual abilities that provide the foundation for the development of spoken language and effective communication. While there are numerous studies examining segmental perception in children with hearing aids (HAs), there are far fewer studies examining suprasegmental perception, especially for children with greater degrees of residual hearing. Examining the relation between acoustic hearing thresholds, and both segmental and suprasegmental perception for children with HAs, may ultimately enable better device recommendations (bilateral HAs, bimodal devices [one CI and one HA in opposite ears], bilateral CIs) for a particular degree of residual hearing. Examining both types of speech perception is important because segmental and suprasegmental cues are affected differentially by the type of hearing device(s) used (i.e., cochlear implant [CI] and/or HA). Additionally, suprathreshold measures, such as frequency resolution ability, may partially predict benefit from amplification and may assist audiologists in making hearing device recommendations. The purpose of this study is to explore the relationship between audibility (via hearing thresholds and speech intelligibility indices), and segmental and suprasegmental speech perception for children with HAs. A secondary goal is to explore the relationships among frequency resolution ability (via spectral modulation detection [SMD] measures), segmental and suprasegmental speech perception, and receptive language in these same children. A prospective cross-sectional design. Twenty-three children, ages 4 yr 11 mo to 11 yr 11 mo, participated in the study. Participants were recruited from pediatric clinic populations, oral schools for the deaf, and mainstream schools. Audiological history and hearing device information were collected from participants and their families. Segmental and suprasegmental speech perception, SMD, and receptive vocabulary skills were assessed. Correlations were calculated to examine the significance (p < 0.05) of relations between audibility and outcome measures. Measures of audibility and segmental speech perception are not significantly correlated, while low-frequency pure-tone average (unaided) is significantly correlated with suprasegmental speech perception. SMD is significantly correlated with all measures (measures of audibility, segmental and suprasegmental perception and vocabulary). Lastly, although age is not significantly correlated with measures of audibility, it is significantly correlated with all other outcome measures. The absence of a significant correlation between audibility and segmental speech perception might be attributed to overall audibility being maximized through well-fit HAs. The significant correlation between low-frequency unaided audibility and suprasegmental measures is likely due to the strong, predominantly low-frequency nature of suprasegmental acoustic properties. Frequency resolution ability, via SMD performance, is significantly correlated with all outcomes and requires further investigation; its significant correlation with vocabulary suggests that linguistic ability may be partially related to frequency resolution ability. Last, all of the outcome measures are significantly correlated with age, suggestive of developmental effects.

Noise History and Auditory Function in Young Adults With and Without Type 1 Diabetes Mellitus

The purpose of this study was to examine the relationship between noise exposure history, type 1 diabetes mellitus (DM), and suprathreshold measures of auditory function. A cross-sectional study was conducted; 20 normal-hearing participants without type 1 DM were matched on age and sex to 20 normal-hearing participants with type 1 DM (n=40). Participants, all having normal audiometric thresholds, completed noise history questionnaires and a battery of auditory physiological tests including transient evoked otoacoustic emissions, distortion product otoacoustic emissions, and auditory brainstem responses (ABR) at 80 dB nHL and at 2 different stimulus rates in both ears. Amplitude and latency for waves I and V are presented. Statistical analysis included analysis of variance and multivariate linear regression. No statistically significant difference for noise exposure history, otoacoustic emissions (OAE), or ABR findings were found between type 1 DM and matched controls. Males and females showed statistically significant differences for OAE amplitudes and ABR amplitude and latencies. However, no statistically significant relationship was found between noise outcomes and OAE or ABR findings. No statistically significant relationship between noise history and our suprathreshold ABR or OAE findings was indicated for individuals with type 1 DM or matched controls. The lack of evidence of noise related neuropathology might be due to inadequate noise exposure or lack of comorbidities in our DM group. Implications of these findings are discussed.

Effects of Recreational Noise on Threshold and Suprathreshold Measures of Auditory Function.

Noise exposure that causes a temporary threshold shift but no permanent threshold shift can cause degeneration of synaptic ribbons and afferent nerve fibers, with a corresponding reduction in wave I amplitude of the auditory brainstem response (ABR) in animals. This form of underlying damage, hypothesized to also occur in humans, has been termed synaptopathy , and it has been hypothesized that there will be a hidden hearing loss consisting of functional deficits at suprathreshold stimulus levels. This study assessed whether recreational noise exposure history was associated with smaller ABR wave I amplitude and poorer performance on suprathreshold auditory test measures. Noise exposure histories were collected from 26 men and 34 women with hearing thresholds ≤ 25 dB hearing loss (HL; 250 Hz to 8 kHz), and a variety of functional suprathreshold hearing tests were performed. Wave I amplitudes of click-evoked ABR were obtained at 70, 80, 90, and 99 dB (nHL) and tone-burst evoked ABR were obtained at 90 dB nHL. Speech recognition performance was measured in quiet and in competing noise, using the Words in Noise test, and the NU-6 word list in broadband noise (BBN). In addition, temporal summation to tonal stimuli was assessed in quiet and in competing BBN. To control for the effects of subclinical conventional hearing loss, distortion product otoacoustic emission amplitude, an indirect measure of outer hair cell integrity, was measured. There was no statistically significant relationship between noise exposure history scores and ABR wave I amplitude in either men or women for any of the ABR conditions. ABR wave I amplitude and noise exposure history were not reliably correlated with suprathreshold functional hearing tests. Taken together, this study found no evidence of noise-induced decreases in ABR wave I amplitude or signal processing in noise in a cohort of subjects with a history of recreational noise exposure.

Suprathreshold measures of taste perception in children - Association with dietary quality and body weight

Childhood obesity is an increasing problem in the Western world, and is affected by a multitude of interacting factors. Recent evidence suggests that taste perception may differ between obese and normal weight children. Evidence also suggests that perception of sweet and bitter taste is linked to differential food liking of various foods. To date, most studies have focused on single food items or food groups, rather than an overall view of dietary quality, and mainly on bitterness. Thus it is unclear whether taste perception is associated with dietary quality in children. Our objective was to examine the link between taste perception, dietary quality and body weight in Irish school children, in conjunction with other known influences of body weight. Taste perception was measured using the gLMS for bitter, salty and sweet stimuli. Detailed dietary intake data were collected from 525 children aged 7–13 via a 3-day diet history. Energy misreporters were identified and excluded from the dietary analyses, leaving n = 483 children. Dietary quality was assessed using Healthy Eating Index. Salivary DNA was collected and analyzed for variations in the bitter receptor gene TAS2R38. Sex differences were observed whereby intensity perception of sweetness was lower in the overweight/obese males, while no association was observed for sweet taste in the females. Despite the differences in weight status, taste perception was not associated with differences in overall dietary quality, measured via HEI score, in this cohort. Prospective cohort studies in children are necessary to better understand the association between taste intensity, food intake and weight over time.

Demographic Predictors of Pain Sensitivity: Results From the OPPERA Study.

The influence of sex, age, and race/ethnicity on various aspects of pain sensitivity, encompassing threshold and suprathreshold measures and multiple stimulus modalities, allows for a more complete evaluation of the relevance of these demographic factors to acute pain perception.

Auditory function in normal-hearing, noise-exposed human ears.

To determine whether suprathreshold measures of auditory function, such as distortion-product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs), are correlated with noise exposure history in normal-hearing human ears. Recent data from animal studies have revealed significant deafferentation of auditory nerve fibers after full recovery from temporary noise-induced hearing loss. Furthermore, these data report smaller ABR wave I amplitudes in noise-exposed animal ears when compared with non-noise-exposed control animals or prenoise exposure amplitudes in the same animal. It is unknown whether a similar phenomenon exists in the normal-hearing, noise-exposed human ear. Thirty normal-hearing human subjects with a range of noise exposure backgrounds (NEBs) participated in this study. NEB was quantified by the use of a noise exposure questionnaire that extensively queried loud sound exposure during the previous 12 months. DPOAEs were collected at three f2s (1, 2, and 4 kHz) over a range of L2s. DPOAE stimulus level began at 80 dB forward-pressure level and decreased in 10 dB steps. Two-channel ABRs were collected in response to click stimuli and 4 kHz tone bursts; one channel used an ipsilateral mastoid electrode and the other an ipsilateral tympanic membrane electrode. ABR stimulus level began at 90 dB nHL and was decreased in 10 dB steps. Amplitudes of waves I and V of the ABR were analyzed. A statistically significant relationship between ABR wave I amplitude and NEB was found for clicked-evoked ABRs recorded at a stimulus level of 90 dB nHL using a mastoid recording electrode. For this condition, ABR wave I amplitudes decreased as a function of NEB. Similar systematic trends were present for ABRs collected in response to clicks and 4 kHz tone bursts at additional suprathreshold stimulation levels (≥70 dB nHL). The relationship weakened and disappeared with decreases in stimulation level (≤60 dB nHL). Similar patterns were present for ABRs collected using a tympanic membrane electrode. However, these relationships were not statistically significant and were weaker and more variable than those collected using a mastoid electrode. In contrast to the findings for ABR wave I, wave V amplitude was not significantly related to NEB. Furthermore, there was no evidence of a systematic relationship between suprathreshold DPOAEs and NEB. A systematic trend of smaller ABR wave I amplitudes was found in normal-hearing human ears with greater amounts of voluntary NEB in response to suprathreshold clicks and 4 kHz tone bursts. These findings are consistent with the data from previous work completed in animals, where the reduction in suprathreshold responses was a result of deafferentation of high-threshold/low-spontaneous rate auditory nerve fibers. These data suggest that a similar mechanism might be operating in human ears after exposure to high sound levels. However, evidence of this damage is only apparent when examining suprathreshold wave I amplitude of the ABR. In contrast, suprathreshold DPOAE level was not significantly related to NEB. This was expected, given noise-induced auditory damage findings in animal ears did not extend to the outer hair cells, the generator for the DPOAE response.

Contrast constancy revisited: the perceived contrast of sinusoidal gratings above threshold.

The contrast sensitivity function of the human visual system, measured with sinusoidal luminance gratings, has an inverted U shape with a peak around 2-4 c/deg. Above threshold, it is thought that luminance gratings of equal physical contrasts but of distinguishably different spatial frequencies are all perceived as having similar contrasts, a phenomenon that has been termed contrast constancy. However, when suprathreshold contrast matches were measured for pairs of luminance gratings whose spatial frequencies were indistinguishable, the matching curves were not flat and followed a similar inverted U shape form as the contrast sensitivity function at threshold. It was therefore suggested that contrast constancy may only be revealed when matching the contrasts of clearly distinguishable spatial frequencies. Here, observers matched the perceived contrasts of suprathreshold luminance gratings of similar but visibly different spatial frequencies between 0.25 and 16 c/deg. The results show that, much like the contrast sensitivity function at threshold, observers are more sensitive to intermediate spatial frequencies (1-6 c/deg) than they are to either higher or to lower spatial frequencies. This tuning is evident when matching reference contrasts of 30-80%, implying a significant role in everyday vision. To demonstrate that these results were not due to local adaptation, the experiment was repeated with shorter stimulus duration, producing the same results. The extent of departure from contrast constancy found in the present study is compared to previously reported suprathreshold measurements. The results are also discussed with consideration to limitations with display apparatus such as monitor blur.

Taste function in early stage treated and untreated Parkinson's disease.

Since brain stem regions associated with early Parkinson's disease (PD) pathology encroach upon those involved in taste function, the ability to taste may be compromised in PD. However, studies on this point have been contradictory. We administered well-validated whole-mouth and regional taste tests that incorporated multiple concentrations of sucrose, citric acid, caffeine, and sodium chloride to 29 early stage PD patients and 29 age-, sex-, and race-matched controls. Electrogustometry was also performed on the anterior tongue. The PD cohort was tested both on and off dopamine-related medications in counterbalanced test sessions. While whole-mouth taste identification test scores for all stimuli were, on average, nominally lower for the PD patients than for the controls, a trend in the opposite direction was noted for the intensity ratings at the lower stimulus concentrations for all stimuli except caffeine. Moreover, regional testing found that PD subjects tended to rate the stimuli, relative to the controls, as more intense on the anterior tongue and less intense on the posterior tongue. No significant associations were evident between taste test scores and UPDRS scores, L-DOPA medication equivalency values, or [(99m)Tc]TRODAT-1 SPECT imaging of dopamine transporter uptake within the striatum and associated regions. Our findings suggest that suprathreshold measures of taste function are influenced by PD and that this disease differentially influences taste function on anterior (CN VII) and posterior (CN IX) tongue regions. Conceivably PD-related damage to CN IX releases central inhibition on CN VII at the level of the brainstem, resulting in enhanced taste intensity on the anterior tongue.

Pregnancy and olfaction: a review.

Many women report a heightened sense of smell during pregnancy. Accounts of these anecdotes have existed for over 100 years, but scientific evidence has been sparse and inconclusive. In this review, I examine the literature on olfactory perception during pregnancy including measures of self-report, olfactory thresholds, odor identification, intensity and hedonic ratings, and disgust. Support for a general decrease in olfactory thresholds (increase in sensitivity) is generally lacking. There is limited evidence that some suprathreshold measures of olfactory perception, such as hedonic ratings of odors, are affected by pregnancy, but these effects are idiosyncratic. In this review, I explore the hypotheses that have been put forth to explain changes in olfactory perception during pregnancy and provide suggestions for further research.