Marginally perceptible outcome feedback, motor learning and implicit processes.

PubMed

Masters, Rich S W; Maxwell, Jon P; Eves, Frank F

2009-09-01

Participants struck 500 golf balls to a concealed target. Outcome feedback was presented at the subjective or objective threshold of awareness of each participant or at a supraliminal threshold. Participants who received fully perceptible (supraliminal) feedback learned to strike the ball onto the target, as did participants who received feedback that was only marginally perceptible (subjective threshold). Participants who received feedback that was not perceptible (objective threshold) showed no learning. Upon transfer to a condition in which the target was unconcealed, performance increased in both the subjective and the objective threshold condition, but decreased in the supraliminal condition. In all three conditions, participants reported minimal declarative knowledge of their movements, suggesting that deliberate hypothesis testing about how best to move in order to perform the motor task successfully was disrupted by the impoverished disposition of the visual outcome feedback. It was concluded that sub-optimally perceptible visual feedback evokes implicit processes.

Current Perception Threshold for Assessment of the Neurological Components of Hand-Arm Vibration Syndrome: A Review

PubMed Central

Kurozawa, Youichi; Hosoda, Takenobu; Nasu, Yoshiro

2010-01-01

Current perception threshold (CPT) has been proposed as a quantitative method for assessment of peripheral sensory nerve function. The aim of this review of selected reports is to provide an overview of CPT measurement for the assessment of the neurological component of hand-arm vibration syndrome (HAVS). The CPT values at 2000 Hz significantly increased for patients with HAVS. This result supports the previous histological findings that demyelination is found predominantly in the peripheral nerves in the hands of men exposed to hand-arm vibration. Diagnostic sensitivity and specificity were high for severe cases of Stockholm sensorineural (SSN) stage 3 compared with non-exposed controls, but not high for mild cases of SSN stage 1 or 2 and for carpal tunnel syndrome associated with HAVS. However, there are only a few studies on the diagnostic validity of the CPT test for the neurological components of HAVS. Further research is needed and should include diagnostic validity and standardizing of measurement conditions such as skin temperature. PMID:24031119

Human responses to electricity: A literature review

NASA Technical Reports Server (NTRS)

Turner, H. S.

1972-01-01

An extensive review of literature on research concerning biomedical sensors is presented for establishing standards for current limiting devices. The physiological and pathological responses of the human, when exposed to electricity are reported including the thresholds: for perception of electricity, pain by electric current, induction of muscular contraction by electric shock, and ventricular fibrillation. The passive electrical properties of cells and tissues are also reported.

Musical duplex perception: perception of figurally good chords with subliminal distinguishing tones.

PubMed

Hall, M D; Pastore, R E

1992-08-01

In a variant of duplex perception with speech, phoneme perception is maintained when distinguishing components are presented below intensities required for separate detection, forming the basis for the claim that a phonetic module takes precedence over nonspeech processing. This finding is replicated with music chords (C major and minor) created by mixing a piano fifth with a sinusoidal distinguishing tone (E or E flat). Individual threshold intensities for detecting E or E flat in the context of the fixed piano tones are established. Chord discrimination thresholds defined by distinguishing tone intensity were determined. Experiment 2 verified masked detection thresholds and subliminal chord identification for experienced musicians. Accurate chord perception was maintained at distinguishing tone intensities nearly 20 dB below the threshold for separate detection. Speech and music findings are argued to demonstrate general perceptual principles.

Threshold Evolution as an Analysis of the Different Pulse Frequencies in Rechargeable Systems for Spinal Cord Stimulation.

PubMed

Abejón, David; Rueda, Pablo; Vallejo, Ricardo

2016-04-01

Pulse frequency (Fc) is one of the most important parameters in neurostimulation, with Pulse Amplitude (Pw) and Amplitude (I). Up to certain Fc, increasing the number of pulses will generate action potentials in neighboring neural structures and may facilitate deeper penetration of the electromagnetic fields. In addition, changes in frequency modify the patient's sensation with stimulation. Fifty patients previously implanted with rechargeable current control spinal cord stimulation. With pulse width fixed at 300 μsec, we stimulated at 26 different Fc values between 40 and 1200 Hz and determine the influence of these changes on different stimulation thresholds: perception threshold (Tp ), therapeutic perception (Tt), and discomfort threshold (Td). Simultaneously, paresthesia coverage of the painful area and patient's sensation and satisfaction related to the quality of stimulation were recorded. Pulse Fc is inversely proportional to stimulation thresholds and this influence is statistically significant (p < 0.05). As Pulse Fc increased from 40 to 1200 Hz, the mean threshold decreases from 7.25 to 1.38 mA (Tp ), 8.17 to 1.63 (Tt ), and 9.20 to 1.85 (Td). Significant differences for Tp and Tt began at 750 Hz (Tp , Tt ) and at 650 Hz for Td. No significant influence was found regarding paresthesia coverage. As expected, Fc affects significantly patient's sensation and satisfaction. Changes in Fc affect the quality of paresthesias. Within the evaluated parameters higher frequencies are inversely proportional to stimulation thresholds and Tt. It seems that Fc is a vital parameter to achieve therapeutic success. Changes in Fc is a useful parameter to modulate the patient's sensory perception. Fc can be successfully used to adjust the quality of the paresthesias and to modify patient's subjective sensation. We showed that as the frequency increases, the patient's satisfaction with the perceived sensation decreases, suggesting that higher Fc may need to be set up at subthreshold amplitude to achieve positive response. © 2016 International Neuromodulation Society.

Using threshold messages to promote physical activity: implications for public perceptions of health effects.

PubMed

Knox, Emily C L; Webb, Oliver J; Esliger, Dale W; Biddle, Stuart J H; Sherar, Lauren B

2014-04-01

The promotion of physical activity (PA) guidelines to the general public is an important issue that lacks empirical investigation. PA campaigns often feature participation thresholds that cite PA guidelines verbatim [e.g., 150 min/week moderate-to-vigorous physical activity (MVPA)]. Some campaigns instead prefer to use generic PA messages (e.g., do as much MVPA as possible). 'Thresholds' may disrupt understanding of the health benefits of modest PA participation. This study examined the perception of health benefits of PA after exposure to PA messages that did and did not contain a duration threshold. Brief structured interviews were conducted with a convenience sample of adults (n = 1100). Participants received a threshold message (150 min/week MVPA), a message that presented the threshold as a minimum; a generic message or no message. Participants rated perceived health effects of seven PA durations. One-way analyses of variance with post hoc tests for group differences were used to assess raw perception ratings for each duration of PA. Recipients of all three messages held more positive perceptions of >150 min/week of MVPA relative to those not receiving any message. For MVPA durations <150 min/week, the generic PA message group perceived the greatest health benefits. Those receiving the threshold message tended to have the least positive perceptions of durations <150 min/week. Threshold messages were associated with lower perceived health benefits for modest PA durations. Campaigns based on threshold messages may be limited when promoting small PA increases at a population level.

Attentional Routes to Conscious Perception

PubMed Central

Chica, Ana B.; Bartolomeo, Paolo

2012-01-01

The relationships between spatial attention and conscious perception are currently the object of intense debate. Recent evidence of double dissociations between attention and consciousness cast doubt on the time-honored concept of attention as a gateway to consciousness. Here we review evidence from behavioral, neurophysiologic, neuropsychological, and neuroimaging experiments, showing that distinct sorts of spatial attention can have different effects on visual conscious perception. While endogenous, or top-down attention, has weak influence on subsequent conscious perception of near-threshold stimuli, exogenous, or bottom-up forms of spatial attention appear instead to be a necessary, although not sufficient, step in the development of reportable visual experiences. Fronto-parietal networks important for spatial attention, with peculiar inter-hemispheric differences, constitute plausible neural substrates for the interactions between exogenous spatial attention and conscious perception. PMID:22279440

Effect of intrathecal baclofen on evoked pain perception: an evoked potentials and quantitative thermal testing study.

PubMed

Kumru, H; Kofler, M; Flores, M C; Portell, E; Robles, V; Leon, N; Vidal, J

2013-08-01

Somatic antinociceptive effects of baclofen have been demonstrated in animal models. We hypothesized that if enhanced thermal or pain sensitivity is produced by loss of gamma-aminobutyric acid (GABA)-ergic tone in the central nervous system, spinal administration of GABA agonists might be predicted to be effective in thermal and/or pain perception changes and pain-related evoked potentials in candidates for intrathecal baclofen (ITB) treatment. Eleven patients with severe spinal cord injury (SCI) who suffered from severe spasticity were evaluated during a 50-μg ITB bolus test. Warm and heat pain thresholds, evoked heat pain perception, and contact heat-evoked potentials (CHEPs) were determined above SCI level from the right and left sides. Nine age- and gender-matched healthy volunteers undergoing repeat testing without any placebo injection served as control group. In patients, heat pain perception threshold increased, and evoked pain perception and amplitude of CHEPs decreased significantly after ITB bolus application in comparison with baseline (p < 0.005), with no change in warm perception threshold. In controls, no significant changes were observed in repeat testing over time. Our findings indicate that ITB modulates heat pain perception threshold, evoked heat pain perception and heat pain-related evoked potentials without inducing warm perception threshold changes in SCI patients. This phenomenon should be taken into account in the clinical evaluation and management of pain in patients receiving baclofen. © 2012 European Federation of International Association for the Study of Pain Chapters.

Tolerability to prolonged lifting tasks. A validation of the recommended limits.

PubMed

Capodaglio, P; Bazzini, G

1997-01-01

Prolonged physical exertion is subjectively regulated by the perception of effort. This preliminary study was conducted to validate the use of subjective perceptions of effort in assessing objectively tolerable workloads for prolonged lifting tasks. Ten healthy male subjects tested their maximal lifting capacity (MLC) on a lift dynamometer (LidoLift, Loredan Biomed., West Sacramento, CA) and underwent incremental and 30-minute endurance lifting tests. Cardiorespiratory parameters were monitored with an oxygen uptake analyzer, mechanical parameters were calculated using a computerized dynamometer. Ratings of perceived exertion were given on Borg's 10-point scale. Physiological responses to repetitive lifting were matched with subjective perceptions. A single-variable statistical regression for power functions was performed to obtain the individual "iso-perception" curves as functions of the mechanical work exerted. We found that the "iso-perception" curve corresponding to a "moderate" perception of effort may represent the individual "tolerance threshold" for prolonged lifting tasks, since physiological responses at this level of intensity did not change significantly and the respiratory exchange ratio was less than one. The individually tolerable weight for lifting tasks lasting 30 min has been expressed as a percentage of the isoinertial MLC value and compared with the currently recommended limits for prolonged lifting tasks (Italian legislation D.L. 626/94). On the basis of our preliminary results a "tolerance threshold" of 20% MLC has been proposed for prolonged lifting tasks.

Human perception of electric fields and ion currents associated with high-voltage DC transmission lines.

PubMed

Blondin, J P; Nguyen, D H; Sbeghen, J; Goulet, D; Cardinal, C; Maruvada, P S; Plante, M; Bailey, W H

1996-01-01

The objective of this study was to assess the ability of humans to detect the presence of DC electric field and ion currents. An exposure chamber simulating conditions present in the vicinity of high-voltage DC (HVDC) lines was designed and built for this purpose. In these experiments, the facility was used to expose observers to DC electric fields up to 50 kV/m and ion current densities up to 120 nA/m2. Forty-eight volunteers (25 women and 23 men) between the ages of 18 and 57 years served as observers. Perception of DC fields was examined by using two psychophysical methods: an adaptive staircase procedure and a rating method derived from signal-detection theory. Subjects completed three different series of observations by using each of these methods; one was conducted without ion currents, and the other two involved various combinations of electric fields and ion currents. Overall, subjects were significantly more likely to detect DC fields as the intensity increased. Observers were able to detect the presence of DC fields alone, but only at high intensities; the average threshold was 45 kV/m. Except in the most sensitive individuals, ion current densities up to 60 nA/m2 did not significantly facilitate the detection of DC fields. However, higher ion current densities were associated with a substantial lowering of sensory thresholds in a large majority of observers. Data analysis also revealed large variations in perceptual thresholds among observers. Normative data indicating DC field and ion current intensities that can be detected by 50% of all observers are provided. In addition, for the most sensitive observers, several other detection proportions were derived from the distribution of individual detection capabilities. These data can form the basis for environmental guidelines relating to the design of HVDC lines.

Color difference threshold determination for acrylic denture base resins.

PubMed

Ren, Jiabao; Lin, Hong; Huang, Qingmei; Liang, Qifan; Zheng, Gang

2015-01-01

This study aimed to set evaluation indicators, i.e., perceptibility and acceptability color difference thresholds, of color stability for acrylic denture base resins for a spectrophotometric assessing method, which offered an alternative to the visual method described in ISO 20795-1:2013. A total of 291 disk specimens 50±1 mm in diameter and 0.5±0.1 mm thick were prepared (ISO 20795-1:2013) and processed through radiation tests in an accelerated aging chamber (ISO 7491:2000) for increasing times of 0 to 42 hours. Color alterations were measured with a spectrophotometer and evaluated using the CIE L*a*b* colorimetric system. Color differences were calculated through the CIEDE2000 color difference formula. Thirty-two dental professionals without color vision deficiencies completed perceptibility and acceptability assessments under controlled conditions in vitro. An S-curve fitting procedure was used to analyze the 50:50% perceptibility and acceptability thresholds. Furthermore, perceptibility and acceptability against the differences of the three color attributes, lightness, chroma, and hue, were also investigated. According to the S-curve fitting procedure, the 50:50% perceptibility threshold was 1.71ΔE00 (r(2)=0.88) and the 50:50% acceptability threshold was 4.00 ΔE00 (r(2)=0.89). Within the limitations of this study, 1.71/4.00 ΔE00 could be used as perceptibility/acceptability thresholds for acrylic denture base resins.

Global Motion Perception in 2-Year-Old Children: A Method for Psychophysical Assessment and Relationships With Clinical Measures of Visual Function

PubMed Central

Yu, Tzu-Ying; Jacobs, Robert J.; Anstice, Nicola S.; Paudel, Nabin; Harding, Jane E.; Thompson, Benjamin

2013-01-01

Purpose. We developed and validated a technique for measuring global motion perception in 2-year-old children, and assessed the relationship between global motion perception and other measures of visual function. Methods. Random dot kinematogram (RDK) stimuli were used to measure motion coherence thresholds in 366 children at risk of neurodevelopmental problems at 24 ± 1 months of age. RDKs of variable coherence were presented and eye movements were analyzed offline to grade the direction of the optokinetic reflex (OKR) for each trial. Motion coherence thresholds were calculated by fitting psychometric functions to the resulting datasets. Test–retest reliability was assessed in 15 children, and motion coherence thresholds were measured in a group of 10 adults using OKR and behavioral responses. Standard age-appropriate optometric tests also were performed. Results. Motion coherence thresholds were measured successfully in 336 (91.8%) children using the OKR technique, but only 31 (8.5%) using behavioral responses. The mean threshold was 41.7 ± 13.5% for 2-year-old children and 3.3 ± 1.2% for adults. Within-assessor reliability and test–retest reliability were high in children. Children's motion coherence thresholds were significantly correlated with stereoacuity (LANG I & II test, ρ = 0.29, P < 0.001; Frisby, ρ = 0.17, P = 0.022), but not with binocular visual acuity (ρ = 0.11, P = 0.07). In adults OKR and behavioral motion coherence thresholds were highly correlated (intraclass correlation = 0.81, P = 0.001). Conclusions. Global motion perception can be measured in 2-year-old children using the OKR. This technique is reliable and data from adults suggest that motion coherence thresholds based on the OKR are related to motion perception. Global motion perception was related to stereoacuity in children. PMID:24282224

Phosphene Perception Relates to Visual Cortex Glutamate Levels and Covaries with Atypical Visuospatial Awareness.

PubMed

Terhune, Devin B; Murray, Elizabeth; Near, Jamie; Stagg, Charlotte J; Cowey, Alan; Cohen Kadosh, Roi

2015-11-01

Phosphenes are illusory visual percepts produced by the application of transcranial magnetic stimulation to occipital cortex. Phosphene thresholds, the minimum stimulation intensity required to reliably produce phosphenes, are widely used as an index of cortical excitability. However, the neural basis of phosphene thresholds and their relationship to individual differences in visual cognition are poorly understood. Here, we investigated the neurochemical basis of phosphene perception by measuring basal GABA and glutamate levels in primary visual cortex using magnetic resonance spectroscopy. We further examined whether phosphene thresholds would relate to the visuospatial phenomenology of grapheme-color synesthesia, a condition characterized by atypical binding and involuntary color photisms. Phosphene thresholds negatively correlated with glutamate concentrations in visual cortex, with lower thresholds associated with elevated glutamate. This relationship was robust, present in both controls and synesthetes, and exhibited neurochemical, topographic, and threshold specificity. Projector synesthetes, who experience color photisms as spatially colocalized with inducing graphemes, displayed lower phosphene thresholds than associator synesthetes, who experience photisms as internal images, with both exhibiting lower thresholds than controls. These results suggest that phosphene perception is driven by interindividual variation in glutamatergic activity in primary visual cortex and relates to cortical processes underlying individual differences in visuospatial awareness. © The Author 2015. Published by Oxford University Press.

Quantitative sensory test for primary restless legs syndrome/Willis-Ekbom disease using the current perception threshold test.

PubMed

Cho, Yong Won; Kang, Min-Sung; Kim, Keun Tae; Do, So Young; Lim, Jung-Geun; Lee, So Young; Motamedi, Gholam K

2017-02-01

Restless legs syndrome/Willis-Ekbom disease (RLS/WED) is a sensorimotor neurological disorder, and it is especially aggravated at night. The purpose of this study was to investigate the diurnal sensory dysfunction in primary RLS/WED using the current perception threshold (CPT) test, compared to healthy controls. Thirty primary RLS/WED subjects and 30 healthy controls were enrolled. The severity of RLS/WED and sleep problems were evaluated in all subjects. Peripheral polyneuropathy was excluded through neurological examination and nerve conduction study. We used the Neurometer ® system for the CPT test and applied three different parameters (2000 Hz, 250 Hz, and 5 Hz), to stimulate both big toes. The CPT test was performed twice, once during the asymptomatic daytime period and again in the evening, when the patients were symptomatic. The mean ages of the RLS/WED group and controls were 50.5 ± 11.7 (22; 73.3% female), and 46.3 ± 11.4 (24; 80.0% female), respectively. The mean international RLS/WED study group severity scale score was 28.6 ± 4.25. There was no significant difference in the current perception thresholds between the RLS/WED patients and controls in daytime. However, the RLS/WED patients had lower mean CPT measurements for all three stimulation protocols in the evening (2000 Hz: 393.2 ± 93.7 vs 430.8 ± 79.6, 250 Hz: 172.0 ± 48.4 vs 198.5 ± 38.2, and 5 Hz: 98.0 ± 34.1 vs 124.6 ± 31.3), while the healthy controls showed no difference. RLS patients showed a lower CPT in the evening. The diurnal variation of hyperalgesia in RLS/WED patients indicates a central (circadian) sensory processing disturbance rather than a peripheral disturbance. Copyright © 2016 Elsevier B.V. All rights reserved.

Identifying cochlear implant channels with poor electrode-neuron interface: partial tripolar, single-channel thresholds and psychophysical tuning curves.

PubMed

Bierer, Julie Arenberg; Faulkner, Kathleen F

2010-04-01

The goal of this study was to evaluate the ability of a threshold measure, made with a restricted electrode configuration, to identify channels exhibiting relatively poor spatial selectivity. With a restricted electrode configuration, channel-to-channel variability in threshold may reflect variations in the interface between the electrodes and auditory neurons (i.e., nerve survival, electrode placement, and tissue impedance). These variations in the electrode-neuron interface should also be reflected in psychophysical tuning curve (PTC) measurements. Specifically, it is hypothesized that high single-channel thresholds obtained with the spatially focused partial tripolar (pTP) electrode configuration are predictive of wide or tip-shifted PTCs. Data were collected from five cochlear implant listeners implanted with the HiRes90k cochlear implant (Advanced Bionics Corp., Sylmar, CA). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the pTP configuration for which a fraction of current (sigma) from a center-active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. Forward-masked PTCs were obtained for channels with the highest, lowest, and median tripolar (sigma = 1 or 0.9) thresholds. The probe channel and level were fixed and presented with either the monopolar (sigma = 0) or a more focused pTP (sigma > or = 0.55) configuration. The masker channel and level were varied, whereas the configuration was fixed to sigma = 0.5. A standard, three-interval, two-alternative forced choice procedure was used for thresholds and masked levels. Single-channel threshold and variability in threshold across channels systematically increased as the compensating current, sigma, increased and the presumed electrical field became more focused. Across subjects, channels with the highest single-channel thresholds, when measured with a narrow, pTP stimulus, had significantly broader PTCs than the lowest threshold channels. In two subjects, the tips of the tuning curves were shifted away from the probe channel. Tuning curves were also wider for the monopolar probes than with pTP probes for both the highest and lowest threshold channels. These results suggest that single-channel thresholds measured with a restricted stimulus can be used to identify cochlear implant channels with poor spatial selectivity. Channels having wide or tip-shifted tuning characteristics would likely not deliver the appropriate spectral information to the intended auditory neurons, leading to suboptimal perception. As a clinical tool, quick identification of impaired channels could lead to patient-specific mapping strategies and result in improved speech and music perception.

The role of alpha oscillations for illusory perception

PubMed Central

Lange, Joachim; Keil, Julian; Schnitzler, Alfons; van Dijk, Hanneke; Weisz, Nathan

2014-01-01

Alpha oscillations are a prominent electrophysiological signal measured across a wide range of species and cortical and subcortical sites. Alpha oscillations have been viewed for a long time as an “idling” rhythm, purely reflecting inactive sites. Despite earlier evidence from neurophysiology, awareness that alpha oscillations can substantially influence perception and behavior has grown only recently in cognitive neuroscience. Evidence for an active role of alpha for perception comes mainly from several visual, near-threshold experiments. In the current review, we extend this view by summarizing studies showing how alpha-defined brain states relate to illusory perception, i.e. cases of perceptual reports that are not “objectively” verifiable by distinct stimuli or stimulus features. These studies demonstrate that ongoing or prestimulus alpha oscillations substantially influence the perception of auditory, visual or multisensory illusions. PMID:24931795

Standardised method of determining vibratory perception thresholds for diagnosis and screening in neurological investigation.

PubMed Central

Goldberg, J M; Lindblom, U

1979-01-01

Vibration threshold determinations were made by means of an electromagnetic vibrator at three sites (carpal, tibial, and tarsal), which were primarily selected for examining patients with polyneuropathy. Because of the vast variation demonstrated for both vibrator output and tissue damping, the thresholds were expressed in terms of amplitude of stimulator movement measured by means of an accelerometer, instead of applied voltage which is commonly used. Statistical analysis revealed a higher power of discimination for amplitude measurements at all three stimulus sites. Digital read-out gave the best statistical result and was also most practical. Reference values obtained from 110 healthy males, 10 to 74 years of age, were highly correlated with age for both upper and lower extremities. The variance of the vibration perception threshold was less than that of the disappearance threshold, and determination of the perception threshold alone may be sufficient in most cases. PMID:501379

The Early College High School and Student Self-Perceptions of College Readiness

ERIC Educational Resources Information Center

Farrell, Tina L.

2009-01-01

High schools in the United States represent the stepping-off point to adulthood, the threshold for students to enter formal training in college, trade school, or the workforce. As our society faces increased demands for creative solutions, innovation, and a more technological workforce, the current high school model is simply antiquated. The Early…

Development of Motion Processing in Children with Autism

ERIC Educational Resources Information Center

Annaz, Dagmara; Remington, Anna; Milne, Elizabeth; Coleman, Mike; Campbell, Ruth; Thomas, Michael S. C.; Swettenham, John

2010-01-01

Recent findings suggest that children with autism may be impaired in the perception of biological motion from moving point-light displays. Some children with autism also have abnormally high motion coherence thresholds. In the current study we tested a group of children with autism and a group of typically developing children aged 5 to 12 years of…

Neurosensory findings among electricians with self-reported remaining symptoms after an electrical injury: A case series.

PubMed

Rådman, Lisa; Gunnarsson, Lars-Gunnar; Nilsagård, Ylva; Nilsson, Tohr

2016-12-01

Symptoms described in previous studies indicate that electrical injury can cause longstanding injuries to the neurosensory nerves. The aim of the present case series was to objectively assess the profile of neurosensory dysfunction in electricians in relation to high voltage or low voltage electrical injury and the "no-let-go phenomenon". Twenty-three Swedish male electricians exposed to electrical injury were studied by using a battery of clinical instruments, including quantitative sensory testing (QST). The clinical test followed a predetermined order of assessments: thermal perceptions thresholds, vibration perception thresholds, tactile gnosis (the Shape and Texture Identification test), manual dexterity (Purdue Pegboard Test), and grip strength. In addition, pain was studied by means of a questionnaire, and a colour chart was used for estimation of white fingers. The main findings in the present case series were reduced thermal perceptions thresholds, where half of the group showed abnormal values for warm thermal perception and/or cold thermal perception. Also, the tactile gnosis and manual dexterity were reduced. High voltage injury was associated with more reduced sensibility compared to those with low voltage. Neurosensory injury can be objectively assessed after an electrical injury by using QST with thermal perception thresholds. The findings are consistent with injuries to small nerve fibres. In the clinical setting thermal perception threshold is therefore recommended, in addition to tests of tactile gnosis and manual dexterity (Purdue Pegboard). Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.

An investigation into the magnitude of the current window and perception of transcutaneous electrical nerve stimulation (TENS) sensation at various frequencies and body sites in healthy human participants.

PubMed

Hughes, Nicola; Bennett, Michael I; Johnson, Mark I

2013-02-01

Strong nonpainful transcutaneous electrical nerve stimulation (TENS) is prerequisite to a successful analgesic outcome although the ease with which this sensation is achieved is likely to depend on the magnitude of current amplitude (mA) between sensory detection threshold (SDT) and pain threshold, that is, the current window. To measure the current window and participant's perception of the comfort of the TENS sensation at different body sites. A repeated measure cross-over study was conducted using 30 healthy adult volunteers. Current amplitudes (mA) of TENS [2 pulses per second (pps); 30 pps; 80 pps] at SDT, pain threshold, and strong nonpainful intensities were measured at the tibia (bone), knee joint (connective tissue), lower back [paraspinal (skeletal) muscle], volar surface of forearm (nerve) and waist (fat). The amplitude to achieve a strong nonpainful intensity was represented as a percentage of the current window. Data were analyzed using repeated measures analysis of variance. Effects were detected for body site and frequency for SDT (P<0.001, P=0.018, respectively), current window (P<0.001, P<0.001, respectively), and strong nonpainful TENS as a percentage of the current window (P=0.002, P<0.001, respectively). The current window was larger for the knee joint compared with tibia (difference [95% confidence interval]=12.76 mA [4.25, 21.28]; P=0.001) and forearm (10.33 mA [2.62, 18.40]; P=0.006), and for the lower back compared with tibia (12.10 mA [1.65, 22.52]; P=0.015) and forearm (9.65 mA [1.06, 18.24]; P=0.019). The current window was larger for 2 pps compared with 30 pps (P<0.001) and 80 pps (P<0.001). Participants rated strong nonpainful TENS as most comfortable at the lower back (P<0.001) and least comfortable at the tibia and forearm (P<0.001). TENS is most comfortable and easiest to titrate to a strong nonpainful intensity when applied over areas of muscle and soft tissue.

Thresholds for the perception of whole-body linear sinusoidal motion in the horizontal plane

NASA Technical Reports Server (NTRS)

Mah, Robert W.; Young, Laurence R.; Steele, Charles R.; Schubert, Earl D.

1989-01-01

An improved linear sled has been developed to provide precise motion stimuli without generating perceptible extraneous motion cues (a noiseless environment). A modified adaptive forced-choice method was employed to determine perceptual thresholds to whole-body linear sinusoidal motion in 25 subjects. Thresholds for the detection of movement in the horizontal plane were found to be lower than those reported previously. At frequencies of 0.2 to 0.5 Hz, thresholds were shown to be independent of frequency, while at frequencies of 1.0 to 3.0 Hz, thresholds showed a decreasing sensitivity with increasing frequency, indicating that the perceptual process is not sensitive to the rate change of acceleration of the motion stimulus. The results suggest that the perception of motion behaves as an integrating accelerometer with a bandwidth of at least 3 Hz.

Do ethnicity and gender have an impact on pain thresholds in minor dermatologic procedures? A study on thermal pain perception thresholds in Asian ethinic groups.

PubMed

Yosipovitch, Gil; Meredith, Gregory; Chan, Yiong Huak; Goh, Chee Leok

2004-02-01

The perception of pain is a personal experience influenced by many factors, including genetic, ethnic and cultural issues. Understanding these perceptions is especially important in dermatologic patients undergoing minor surgical operations and who often differ in their pain response to surgical treatments. Little is known about how these differences affect the perception of experimental pain. The purpose of this study was to determine experimental pain perception differences in three distinct East Asian ethnic populations. Pain thresholds were examined with a psychophysical computerized quantitative thermal sensory testing device (TSA 2001) in healthy volunteers recruited from three different Asian ethnic groups. Using the methods of limits, experimental pain perception threshold was measured on the forehead and volar aspect of the forearm in 49 healthy subjects. The measurements were then repeated after skin barrier perturbation with adhesive tape stripping of the stratum corneum. All three ethnic groups were analyzed separately with respect to age, gender educational level and skin type. A total of 20 Chinese, 14 Malay and 15 Indian subjects completed the study. Thermal pain thresholds were similar in all three ethnic groups before and after tape strippings. No significant differences were noted between genders. Using quantitative sensory thermal testing, we demonstrated that no significant differences in pain occur between different races and genders.

Evaluation of participants' perception and taste thresholds with a zirconia palatal plate.

PubMed

Wada, Takeshi; Takano, Tomofumi; Tasaka, Akinori; Ueda, Takayuki; Sakurai, Kaoru

2016-10-01

Zirconia and cobalt-chromium can withstand a similar degree of loading. Therefore, using a zirconia base for removable dentures could allow the thickness of the palatal area to be reduced similarly to metal base dentures. We hypothesized that zirconia palatal plate for removable dentures provides a high level of participants' perception without influencing taste thresholds. The purpose of this study was to evaluate the participants' perception and taste thresholds of zirconia palatal plate. Palatal plates fabricated using acrylic resin, zirconia, and cobalt-chromium alloy were inserted into healthy individuals. Taste thresholds were investigated using the whole-mouth gustatory test, and participants' perception was evaluated using the 100-mm visual analog scale to assess the ease of pronunciation, ease of swallowing, sensation of temperature, metallic taste, sensation of foreign body, subjective sensory about weight, adhesiveness of chewing gum, and general satisfaction. For the taste thresholds, no significant differences were noted in sweet, salty, sour, bitter, or umami tastes among participants wearing no plate, or the resin, zirconia, and metal plates. Speech was easier and foreign body sensation was lower with the zirconia plate than with the resin plate. Evaluation of the adhesiveness of chewing gum showed that chewing gum does not readily adhere to the zirconia plate in comparison with the metal plate. The comprehensive participants' perception of the zirconia plate was evaluated as being superior to the resin plate. A zirconia palatal plate provides a high level of participants' perception without influencing taste thresholds. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Gravity matters: Motion perceptions modified by direction and body position.

PubMed

Claassen, Jens; Bardins, Stanislavs; Spiegel, Rainer; Strupp, Michael; Kalla, Roger

2016-07-01

Motion coherence thresholds are consistently higher at lower velocities. In this study we analysed the influence of the position and direction of moving objects on their perception and thereby the influence of gravity. This paradigm allows a differentiation to be made between coherent and randomly moving objects in an upright and a reclining position with a horizontal or vertical axis of motion. 18 young healthy participants were examined in this coherent threshold paradigm. Motion coherence thresholds were significantly lower when position and motion were congruent with gravity independent of motion velocity (p=0.024). In the other conditions higher motion coherence thresholds (MCT) were found at lower velocities and vice versa (p<0.001). This result confirms previous studies with higher MCT at lower velocity but is in contrast to studies concerning perception of virtual turns and optokinetic nystagmus, in which differences of perception were due to different directions irrespective of body position, i.e. perception took place in an egocentric reference frame. Since the observed differences occurred in an upright position only, perception of coherent motion in this study is defined by an earth-centered reference frame rather than by an ego-centric frame. Copyright © 2016 Elsevier Inc. All rights reserved.

Mechanism of biological effects observed in honey bees (Apis mellifera, L. ) hived under extra-high-voltage transmission lines: implications derived from bee exposure to simulated intense electric fields and shocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bindokas, V.P.; Gauger, J.R.; Greenberg, B.

This work explores mechanisms for disturbance of honey bee colonies under a 765 kV, 60-Hz transmission line (electric (E) field = 7 kV/m) observed in previous studies. Proposed mechanisms fell into two categories: direct bee perception of enhanced in-hive E fields and perception of shock from induced currents. The adverse biological effects could be reproduced in simulations where only the worker bees were exposed to shock or to E field in elongated hive entranceways (= tunnels). We now report the results of full-scale experiments using the tunnel exposure scheme, which assesses the contribution of shock and intense E field tomore » colony disturbance. Exposure of worker bees (1400 h) to 60-Hz E fields including 100 kV/m under moisture-free conditions within a nonconductive tunnel causes no deleterious affect on colony behavior. Exposure of bees in conductive (e.g., wet) tunnels produces bee disturbance, increased mortality, abnormal propolization, and possible impairment of colony growth. We propose that this substrate dependence of bee disturbance is the result of perception of shock from coupled body currents and enhanced current densities postulated to exist in the legs and thorax of bees on conductors. Similarly, disturbance occurs when bees are exposed to step-potential-induced currents. At 275-350 nA single bees are disturbed; at 600 nA bees begin abnormal propolization behavior; and stinging occurs at 900 nA. We conclude that biological effects seen in bee colonies under a transmission line are primarily the result of electric shock from induced hive currents. This evaluation is based on the limited effects of E-field exposure in tunnels, the observed disturbance thresholds caused by shocks in tunnels, and the ability of hives exposed under a transmission line to source currents 100-1,000 times the shock thresholds.« less

Cochlear implant characteristics and speech perception skills of adolescents with long-term device use.

PubMed

Davidson, Lisa S; Geers, Ann E; Brenner, Christine

2010-10-01

Updated cochlear implant technology and optimized fitting can have a substantial impact on speech perception. The effects of upgrades in processor technology and aided thresholds on word recognition at soft input levels and sentence recognition in noise were examined. We hypothesized that updated speech processors and lower aided thresholds would allow improved recognition of soft speech without compromising performance in noise. 109 teenagers who had used a Nucleus 22-cochlear implant since preschool were tested with their current speech processor(s) (101 unilateral and 8 bilateral): 13 used the Spectra, 22 the ESPrit 22, 61 the ESPrit 3G, and 13 the Freedom. The Lexical Neighborhood Test (LNT) was administered at 70 and 50 dB SPL and the Bamford Kowal Bench sentences were administered in quiet and in noise. Aided thresholds were obtained for frequency-modulated tones from 250 to 4,000 Hz. Results were analyzed using repeated measures analysis of variance. Aided thresholds for the Freedom/3G group were significantly lower (better) than the Spectra/Sprint group. LNT scores at 50 dB were significantly higher for the Freedom/3G group. No significant differences between the 2 groups were found for the LNT at 70 or sentences in quiet or noise. Adolescents using updated processors that allowed for aided detection thresholds of 30 dB HL or better performed the best at soft levels. The BKB in noise results suggest that greater access to soft speech does not compromise listening in noise.

Effects of Acupuncture on Sensory Perception: A Systematic Review and Meta-Analysis

PubMed Central

Baeumler, Petra I.; Fleckenstein, Johannes; Takayama, Shin; Simang, Michael; Seki, Takashi; Irnich, Dominik

2014-01-01

Background The effect of acupuncture on sensory perception has never been systematically reviewed; although, studies on acupuncture mechanisms are frequently based on the idea that changes in sensory thresholds reflect its effect on the nervous system. Methods Pubmed, EMBASE and Scopus were screened for studies investigating the effect of acupuncture on thermal or mechanical detection or pain thresholds in humans published in English or German. A meta-analysis of high quality studies was performed. Results Out of 3007 identified articles 85 were included. Sixty five studies showed that acupuncture affects at least one sensory threshold. Most studies assessed the pressure pain threshold of which 80% reported an increase after acupuncture. Significant short- and long-term effects on the pressure pain threshold in pain patients were revealed by two meta-analyses including four and two high quality studies, respectively. In over 60% of studies, acupuncture reduced sensitivity to noxious thermal stimuli, but measuring methods might influence results. Few but consistent data indicate that acupuncture reduces pin-prick like pain but not mechanical detection. Results on thermal detection are heterogeneous. Sensory threshold changes were equally frequent reported after manual acupuncture as after electroacupuncture. Among 48 sham-controlled studies, 25 showed stronger effects on sensory thresholds through verum than through sham acupuncture, but in 9 studies significant threshold changes were also observed after sham acupuncture. Overall, there is a lack of high quality acupuncture studies applying comprehensive assessments of sensory perception. Conclusions Our findings indicate that acupuncture affects sensory perception. Results are most compelling for the pressure pain threshold, especially in pain conditions associated with tenderness. Sham acupuncture can also cause such effects. Future studies should incorporate comprehensive, standardized assessments of sensory profiles in order to fully characterize its effect on sensory perception and to explore the predictive value of sensory profiles for the effectiveness of acupuncture. PMID:25502787

Effects of acupuncture on sensory perception: a systematic review and meta-analysis.

PubMed

Baeumler, Petra I; Fleckenstein, Johannes; Takayama, Shin; Simang, Michael; Seki, Takashi; Irnich, Dominik

2014-01-01

The effect of acupuncture on sensory perception has never been systematically reviewed; although, studies on acupuncture mechanisms are frequently based on the idea that changes in sensory thresholds reflect its effect on the nervous system. Pubmed, EMBASE and Scopus were screened for studies investigating the effect of acupuncture on thermal or mechanical detection or pain thresholds in humans published in English or German. A meta-analysis of high quality studies was performed. Out of 3007 identified articles 85 were included. Sixty five studies showed that acupuncture affects at least one sensory threshold. Most studies assessed the pressure pain threshold of which 80% reported an increase after acupuncture. Significant short- and long-term effects on the pressure pain threshold in pain patients were revealed by two meta-analyses including four and two high quality studies, respectively. In over 60% of studies, acupuncture reduced sensitivity to noxious thermal stimuli, but measuring methods might influence results. Few but consistent data indicate that acupuncture reduces pin-prick like pain but not mechanical detection. Results on thermal detection are heterogeneous. Sensory threshold changes were equally frequent reported after manual acupuncture as after electroacupuncture. Among 48 sham-controlled studies, 25 showed stronger effects on sensory thresholds through verum than through sham acupuncture, but in 9 studies significant threshold changes were also observed after sham acupuncture. Overall, there is a lack of high quality acupuncture studies applying comprehensive assessments of sensory perception. Our findings indicate that acupuncture affects sensory perception. Results are most compelling for the pressure pain threshold, especially in pain conditions associated with tenderness. Sham acupuncture can also cause such effects. Future studies should incorporate comprehensive, standardized assessments of sensory profiles in order to fully characterize its effect on sensory perception and to explore the predictive value of sensory profiles for the effectiveness of acupuncture.

Acoustic pressure waves induced in human heads by RF pulses from high-field MRI scanners.

PubMed

Lin, James C; Wang, Zhangwei

2010-04-01

The current evolution toward greater image resolution from magnetic resonance image (MRI) scanners has prompted the exploration of higher strength magnetic fields and use of higher levels of radio frequencies (RFs). Auditory perception of RF pulses by humans has been reported during MRI with head coils. It has shown that the mechanism of interaction for the auditory effect is caused by an RF pulse-induced thermoelastic pressure wave inside the head. We report a computational study of the intensity and frequency of thermoelastic pressure waves generated by RF pulses in the human head inside high-field MRI and clinical scanners. The U.S. Food and Drug Administration (U.S. FDA) guides limit the local specific absorption rate (SAR) in the body-including the head-to 8 W kg(-1). We present results as functions of SAR and show that for a given SAR the peak acoustic pressures generated in the anatomic head model were essentially the same at 64, 300, and 400 MHz (1.5, 7.0, and 9.4 T). Pressures generated in the anatomic head are comparable to the threshold pressure of 20 mPa for sound perception by humans at the cochlea for 4 W kg(-1). Moreover, results indicate that the peak acoustic pressure in the brain is only 2 to 3 times the auditory threshold at the U.S. FDA guideline of 8 W kg(-1). Even at a high SAR of 20 W kg(-1), where the acoustic pressure in the brain could be more than 7 times the auditory threshold, the sound pressure levels would not be more than 17 db above threshold of perception at the cochlea.

Identifying cochlear implant channels with poor electrode-neuron interface: partial tripolar, single-channel thresholds and psychophysical tuning curves

PubMed Central

Bierer, Julie Arenberg; Faulkner, Kathleen F.

2010-01-01

Objectives The goal of this study was to evaluate the ability of a threshold measure, made with a restricted electrode configuration, to identify channels exhibiting relatively poor spatial selectivity. With a restricted electrode configuration, channel-to-channel variability in threshold may reflect variations in the interface between the electrodes and auditory neurons (i.e., nerve survival, electrode placement, tissue impedance). These variations in the electrode-neuron interface should also be reflected in psychophysical tuning curve measurements. Specifically, it is hypothesized that high single-channel thresholds obtained with the spatially focused partial tripolar electrode configuration are predictive of wide or tip-shifted psychophysical tuning curves. Design Data were collected from five cochlear implant listeners implanted with the HiRes 90k cochlear implant (Advanced Bionics). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the partial tripolar configuration, for which a fraction of current (σ) from a center active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. Forward-masked psychophysical tuning curves were obtained for channels with the highest, lowest, and median tripolar (σ=1 or 0.9) thresholds. The probe channel and level were fixed and presented with either the monopolar (σ=0) or a more focused partial tripolar (σ ≥ 0.55) configuration. The masker channel and level were varied while the configuration was fixed to σ = 0.5. A standard, three-interval, two-alternative forced choice procedure was used for thresholds and masked levels. Results Single-channel threshold and variability in threshold across channels systematically increased as the compensating current, σ, increased and the presumed electrical field became more focused. Across subjects, channels with the highest single-channel thresholds, when measured with a narrow, partial tripolar stimulus, had significantly broader psychophysical tuning curves than the lowest threshold channels. In two subjects, the tips of the tuning curves were shifted away from the probe channel. Tuning curves were also wider for the monopolar probes than with partial tripolar probes, for both the highest and lowest threshold channels. Conclusions These results suggest that single-channel thresholds measured with a restricted stimulus can be used to identify cochlear implant channels with poor spatial selectivity. Channels having wide or tip-shifted tuning characteristics would likely not deliver the appropriate spectral information to the intended auditory neurons, leading to suboptimal perception. As a clinical tool, quick identification of impaired channels could lead to patient-specific mapping strategies and result in improved speech and music perception. PMID:20090533

[Value of cumulative electrodermal responses in subliminal auditory perception. A preliminary study].

PubMed

Borgeat, F; Pannetier, M F

1982-01-01

This exploratory study examined the usefulness of averaging electrodermal potential responses for research on subliminal auditory perception. Eighteen female subjects were exposed to three kinds (emotional, neutral and 1000 Hz tone) of auditory stimulation which were repeated six times at three intensities (detection threshold, 10 dB under this threshold and 10 dB above identification threshold). Analysis of electrodermal potential responses showed that the number of responses was related to the emotionality of subliminal stimuli presented at detection threshold but not at 10 dB under it. The data interpretation proposed refers to perceptual defence theory. This study indicates that electrodermal response count constitutes a useful measure for subliminal auditory perception research, but averaging those responses was not shown to bring additional information.

Time perception deficit in children with ADHD.

PubMed

Yang, Binrang; Chan, Raymond C K; Zou, Xiaobing; Jing, Jin; Mai, Jianning; Li, Jing

2007-09-19

Time perception deficit has been demonstrated in children with attention deficit hyperactivity disorder (ADHD) by using time production and time reproduction tasks. The impact of motor demand, however, has not yet been fully examined. The current study, which is reported herein, aimed to investigate the pure time perception of Chinese children with ADHD by using a duration discrimination task. A battery of tests that were specifically designed to measure time perception and other related abilities, such as inhibition, attention, and working memory, was administered to 40 children with ADHD and to 40 demographically matched healthy children. A repeated measure MANOVA indicated that children with ADHD showed significantly higher discrimination thresholds than did healthy controls, and there was an interaction effect between group and duration. Pairwise comparison indicated that children with ADHD were less accurate in discriminating duration at either target duration. Working memory (Corsi blocks task) was related to the discrimination threshold at a duration of 800 ms after controlling for full-scale IQ (FIQ) in the ADHD group, but this did not survive the Bonferroni correction. The results indicated that children with ADHD may have perceptual deficits in time discrimination. They needed a greater difference between the comparison and target intervals to discriminate the short, median, and long durations reliably. This study provides further support for the existence of a generic time perception deficit, which is probably due to the involvement of a dysfunctional fronto-striato-cerebellar network in this capacity, especially the presence of deficits in basic internal timing mechanisms.

Vibrotactile perception and effects of short-term exposure to hand-arm vibration.

PubMed

Burström, Lage; Lundström, Ronnie; Hagberg, Mats; Nilsson, Tohr

2009-07-01

This study clarifies whether the established frequency weighting procedure for evaluating exposure to hand-transmitted vibration can effectively evaluate the temporary changes in vibrotactile perception thresholds due to pre-exposure to vibration. In addition, this study investigates the relationship between changes of the vibrotactile perception thresholds and the normalized energy-equivalent frequency-weighted acceleration. The fingers of 10 healthy subjects, five male and five female, were exposed to vibration under 16 conditions with a combination of different frequencies, intensities, and exposure times. The vibration frequencies were 31.5 and 125 Hz and exposure lasted between 2 and 16 min. According to International Organization for Standardization (ISO) 5349-1, the energy-equivalent frequency-weighted acceleration for the experimental time of 16 min is 2.5 or 5.0 m s(-2) root-mean-square, corresponding to a 8-h equivalent acceleration, A(8), of approximately 0.5 and 0.9 m s(-2), respectively. A measure of the vibrotactile perception thresholds was conducted before the different exposures to vibration. Immediately after the vibration exposure, the acute effect was measured continuously on the exposed index finger for the first 75 s, followed by 30 s of measures every minute for a maximum of 10 min. If the subject's thresholds had not recovered, the measures continued for a maximum of 30 min with measurements taken every 5 min. Pre-exposure to vibration significantly influenced vibrotactile thresholds. This study concludes that the influence on the thresholds depends on the frequency of the vibration stimuli. Increased equivalent frequency-weighted acceleration resulted in a significant change in threshold, but the thresholds were unaffected when changes in the vibration magnitude were expressed as the frequency-weighted acceleration or the unweighted acceleration. Moreover, the frequency of the pre-vibration exposure significantly influenced (up to 25 min after exposure) recovery time of the vibrotactile thresholds. This study shows that the frequency weighting procedure in ISO 5349-1 is unable to predict the produced acute changes in the vibrotactile perception. Moreover, the results imply that the calculation of the 'energy-equivalent' frequency-weighted acceleration does not reflect the acute changes of the vibration perception thresholds due to pre-exposure to vibration. Furthermore, when testing for the vibrotactile thresholds, exposure to vibration on the day of a test might influence the results. Until further knowledge is obtained, the previous practice of 3 h avoidance of vibration exposure before assessment is recommended.

Cold perception and cutaneous microvascular response to local cooling at different cooling temperatures.

PubMed

Music, Mark; Finderle, Zarko; Cankar, Ksenija

2011-05-01

The aim of the present study was to investigate the effect of quantitatively measured cold perception (CP) thresholds on microcirculatory response to local cooling as measured by direct and indirect response of laser-Doppler (LD) flux during local cooling at different temperatures. The CP thresholds were measured in 18 healthy males using the Marstock method (thermode placed on the thenar). The direct (at the cooling site) and indirect (on contralateral hand) LD flux responses were recorded during immersion of the hand in a water bath at 20°C, 15°C, and 10°C. The cold perception threshold correlated (linear regression analysis, Pearson correlation) with the indirect LD flux response at cooling temperatures 20°C (r=0.782, p<0.01) and 15°C (r=0.605, p<0.01). In contrast, there was no correlation between the CP threshold and the indirect LD flux response during cooling in water at 10°C. The results demonstrate that during local cooling, depending on the cooling temperature used, cold perception threshold influences indirect LD flux response. Copyright © 2011 Elsevier Inc. All rights reserved.

Auditory-motor integration of subliminal phase shifts in tapping: better than auditory discrimination would predict.

PubMed

Kagerer, Florian A; Viswanathan, Priya; Contreras-Vidal, Jose L; Whitall, Jill

2014-04-01

Unilateral tapping studies have shown that adults adjust to both perceptible and subliminal changes in phase or frequency. This study focuses on the phase responses to abrupt/perceptible and gradual/subliminal changes in auditory-motor relations during alternating bilateral tapping. We investigated these responses in participants with and without good perceptual acuity as determined by an auditory threshold test. Non-musician adults (nine per group) alternately tapped their index fingers in synchrony with auditory cues set at a frequency of 1.4 Hz. Both groups modulated their responses (with no after-effects) to perceptible and to subliminal changes as low as a 5° change in phase. The high-threshold participants were more variable than the adults with low threshold in their responses in the gradual condition set. Both groups demonstrated a synchronization asymmetry between dominant and non-dominant hands associated with the abrupt condition and the later blocks of the gradual condition. Our findings extend previous work in unilateral tapping and suggest (1) no relationship between a discrimination threshold and perceptible auditory-motor integration and (2) a noisier sub-cortical circuitry in those with higher thresholds.

Auditory-motor integration of subliminal phase shifts in tapping: Better than auditory discrimination would predict

PubMed Central

Kagerer, Florian A.; Viswanathan, Priya; Contreras-Vidal, Jose L.; Whitall, Jill

2014-01-01

Unilateral tapping studies have shown that adults adjust to both perceptible and subliminal changes in phase or frequency. This study focuses on the phase responses to abrupt/perceptible and gradual/subliminal changes in auditory-motor relations during alternating bilateral tapping. We investigated these responses in participants with and without good perceptual acuity as determined by an auditory threshold test. Non-musician adults (9 per group) alternately tapped their index fingers in synchrony with auditory cues set at a frequency of 1.4 Hz. Both groups modulated their responses (with no after-effects) to perceptible and to subliminal changes as low as a 5° change in phase. The high threshold participants were more variable than the adults with low threshold in their responses in the gradual condition set (p=0.05). Both groups demonstrated a synchronization asymmetry between dominant and non-dominant hands associated with the abrupt condition and the later blocks of the gradual condition. Our findings extend previous work in unilateral tapping and suggest (1) no relationship between a discrimination threshold and perceptible auditory-motor integration and (2) a noisier subcortical circuitry in those with higher thresholds. PMID:24449013

Result on speech perception after conversion from Spectra® to Freedom®.

PubMed

Magalhães, Ana Tereza de Matos; Goffi-Gomez, Maria Valéria Schmidt; Hoshino, Ana Cristina; Tsuji, Robinson Koji; Bento, Ricardo Ferreira; Brito, Rubens

2012-04-01

New technology in the Freedom® speech processor for cochlear implants was developed to improve how incoming acoustic sound is processed; this applies not only for new users, but also for previous generations of cochlear implants. To identify the contribution of this technology-- the Nucleus 22®--on speech perception tests in silence and in noise, and on audiometric thresholds. A cross-sectional cohort study was undertaken. Seventeen patients were selected. The last map based on the Spectra® was revised and optimized before starting the tests. Troubleshooting was used to identify malfunction. To identify the contribution of the Freedom® technology for the Nucleus22®, auditory thresholds and speech perception tests were performed in free field in sound-proof booths. Recorded monosyllables and sentences in silence and in noise (SNR = 0dB) were presented at 60 dBSPL. The nonparametric Wilcoxon test for paired data was used to compare groups. Freedom® applied for the Nucleus22® showed a statistically significant difference in all speech perception tests and audiometric thresholds. The Freedom® technology improved the performance of speech perception and audiometric thresholds of patients with Nucleus 22®.

Reproducibility of current perception threshold with the Neurometer(®) vs the Stimpod NMS450 peripheral nerve stimulator in healthy volunteers: an observational study.

PubMed

Tsui, Ban C H; Shakespeare, Timothy J; Leung, Danika H; Tsui, Jeremy H; Corry, Gareth N

2013-08-01

Current methods of assessing nerve blocks, such as loss of perception to cold sensation, are subjective at best. Transcutaneous nerve stimulation is an alternative method that has previously been used to measure the current perception threshold (CPT) in individuals with neuropathic conditions, and various devices to measure CPT are commercially available. Nevertheless, the device must provide reproducible results to be used as an objective tool for assessing nerve blocks. We recruited ten healthy volunteers to examine CPT reproducibility using the Neurometer(®) and the Stimpod NMS450 peripheral nerve stimulator. Each subject's CPT was determined for the median (second digit) and ulnar (fifth digit) nerve sensory distributions on both hands - with the Neurometer at 5 Hz, 250 Hz, and 2000 Hz and with the Stimpod at pulse widths of 0.1 msec, 0.3 msec, 0.5 msec, and 1.0 msec, both at 5 Hz and 2 Hz. Intraclass correlation coefficients (ICC) were also calculated to assess reproducibility; acceptable ICCs were defined as ≥ 0.4. The ICC values for the Stimpod ranged from 0.425-0.79, depending on pulse width, digit, and stimulation; ICCs for the Neurometer were 0.615 and 0.735 at 250 and 2,000 Hz, respectively. These values were considered acceptable; however, the Neurometer performed less efficiently at 5 Hz (ICCs for the second and fifth digits were 0.292 and 0.318, respectively). Overall, the Stimpod device displayed good to excellent reproducibility in measuring CPT in healthy volunteers. The Neurometer displayed poor reproducibility at low frequency (5 Hz). These results suggest that peripheral nerve stimulators may be potential devices for measuring CPT to assess nerve blocks.

Intensity coding in electric hearing: effects of electrode configurations and stimulation waveforms.

PubMed

Chua, Tiffany Elise H; Bachman, Mark; Zeng, Fan-Gang

2011-01-01

Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem. The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were five Clarion cochlear implant users. For each subject, data from apical, middle, and basal electrode positions were collected when possible. Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels. The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen.

Whole body vibration training improves vibration perception threshold in healthy young adults: A randomized clinical trial pilot study.

PubMed

Hernandez-Mocholi, M A; Dominguez-Muñoz, F J; Corzo, H; Silva, S Cs; Adsuar, J C; Gusi, N

2016-03-01

Loss of foot sensitivity is a relevant parameter to assess and prevent in several diseases. It is crucial to determine the vibro-tactile sensitivity threshold response to acute conditions to explore innovative monitor tools and interventions to prevent and treat this challenge. The aims were: 1) to analyze the acute effects of a single whole body vibration session (4min-18Hz-4mm) on vibro-tactile perception threshold in healthy young adults. 2) to analyze the 48 hours effects of 3 whole body vibration sessions on vibro-tactile perception threshold in healthy young adults. A randomized controlled clinical trial over 3 sessions of whole body vibration intervention or 3 sessions of placebo intervention. Twenty-eight healthy young adults were included: 11 experimental group and 12 placebo group. The experimental group performed 3 sessions of WBV while the placebo group performed 3 sessions of placebo intervention. The vibro-tactile threshold increased right after a single WBV session in comparison with placebo. Nevertheless, after 3 whole body vibration sessions and 48 hours, the threshold decreased to values lower than the initial. The acute response of the vibro-tactile threshold to one whole body vibration session increased, but the 48 hours short-term response of this threshold decreased in healthy young adults.

Translucency thresholds for dental materials.

PubMed

Salas, Marianne; Lucena, Cristina; Herrera, Luis Javier; Yebra, Ana; Della Bona, Alvaro; Pérez, María M

2018-05-12

To determine the translucency acceptability and perceptibility thresholds for dental resin composites using CIEDE2000 and CIELAB color difference formulas. A 30-observer panel performed perceptibility and acceptability judgments on 50 pairs of resin composites discs (diameter: 10mm; thickness: 1mm). Disc pair differences for the Translucency Parameter (ΔTP) were calculated using both color difference formulas (ΔTP 00 ranged from 0.11 to 7.98, and ΔTP ab ranged from 0.01 to 12.79). A Takagi-Sugeno-Kang (TSK) Fuzzy Approximation was used as fitting procedure. From the resultant fitting curves, the 95% confidence intervals were estimated and the 50:50% translucency perceptibility and acceptability thresholds (TPT and TAT) were calculated. Differences between thresholds were statistically analyzed using Student t tests (α=0.05). CIEDE2000 50:50% TPT was 0.62 and TAT was 2.62. Corresponding CIELAB values were 1.33 and 4.43, respectively. Translucency perceptibility and acceptability thresholds were significantly different using both color difference formulas (p=0.01 for TPT and p=0.005 for TAT). CIEDE2000 color difference formula provided a better data fit than CIELAB formula. The visual translucency difference thresholds determined with CIEDE2000 color difference formula can serve as reference values in the selection of resin composites and evaluation of its clinical performance. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Reading Behind the Lines: The Factors Affecting the Text Reception Threshold in Hearing Aid Users.

PubMed

Zekveld, Adriana A; Pronk, Marieke; Danielsson, Henrik; Rönnberg, Jerker

2018-03-15

The visual Text Reception Threshold (TRT) test (Zekveld et al., 2007) has been designed to assess modality-general factors relevant for speech perception in noise. In the last decade, the test has been adopted in audiology labs worldwide. The 1st aim of this study was to examine which factors best predict interindividual differences in the TRT. Second, we aimed to assess the relationships between the TRT and the speech reception thresholds (SRTs) estimated in various conditions. First, we reviewed studies reporting relationships between the TRT and the auditory and/or cognitive factors and formulated specific hypotheses regarding the TRT predictors. These hypotheses were tested using a prediction model applied to a rich data set of 180 hearing aid users. In separate association models, we tested the relationships between the TRT and the various SRTs and subjective hearing difficulties, while taking into account potential confounding variables. The results of the prediction model indicate that the TRT is predicted by the ability to fill in missing words in incomplete sentences, by lexical access speed, and by working memory capacity. Furthermore, in line with previous studies, a moderate association between higher age, poorer pure-tone hearing acuity, and poorer TRTs was observed. Better TRTs were associated with better SRTs for the correct perception of 50% of Hagerman matrix sentences in a 4-talker babble, as well as with better subjective ratings of speech perception. Age and pure-tone hearing thresholds significantly confounded these associations. The associations of the TRT with SRTs estimated in other conditions and with subjective qualities of hearing were not statistically significant when adjusting for age and pure-tone average. We conclude that the abilities tapped into by the TRT test include processes relevant for speeded lexical decision making when completing partly masked sentences and that these processes require working memory capacity. Furthermore, the TRT is associated with the SRT of hearing aid users as estimated in a challenging condition that includes informational masking and with experienced difficulties with speech perception in daily-life conditions. The current results underline the value of using the TRT test in studies involving speech perception and aid in the interpretation of findings acquired using the test.

Simulated microgravity [bed rest] has little influence on taste, odor or trigeminal sensitivity

NASA Technical Reports Server (NTRS)

Vickers, Z. M.; Rice, B. L.; Rose, M. S.; Lane, H. W.

2001-01-01

Anecdotal evidence suggests that astronauts' perceptions of foods in space flight may differ from their perceptions of the same foods on Earth. Fluid shifts toward the head experienced in space may alter the astronauts' sensitivity to odors and tastes, producing altered perceptions. Our objective was to determine whether head-down bed rest, which produces similar fluid shifts, would produce changes in sensitivity to taste, odor or trigeminal sensations. Six subjects were rested three times prior to bed rest, three times during bed rest and two times after bed rest to determine their threshold sensitivity to the odors isoamylbutyrate and menthone, the tastants sucrose, sodium chloride, citric acid, quinine and monosodium glutamate, and to capsaicin. Thresholds were measured using a modified staircase procedure. Self-reported congestion was also recorded at each test time. Thresholds for monosodium glutamate where slightly higher during bed rest. None of the other thresholds were altered by bed rest.

Within-subjects comparison of the HiRes and Fidelity120 speech processing strategies: speech perception and its relation to place-pitch sensitivity.

PubMed

Donaldson, Gail S; Dawson, Patricia K; Borden, Lamar Z

2011-01-01

Previous studies have confirmed that current steering can increase the number of discriminable pitches available to many cochlear implant (CI) users; however, the ability to perceive additional pitches has not been linked to improved speech perception. The primary goals of this study were to determine (1) whether adult CI users can achieve higher levels of spectral cue transmission with a speech processing strategy that implements current steering (Fidelity120) than with a predecessor strategy (HiRes) and, if so, (2) whether the magnitude of improvement can be predicted from individual differences in place-pitch sensitivity. A secondary goal was to determine whether Fidelity120 supports higher levels of speech recognition in noise than HiRes. A within-subjects repeated measures design evaluated speech perception performance with Fidelity120 relative to HiRes in 10 adult CI users. Subjects used the novel strategy (either HiRes or Fidelity120) for 8 wks during the main study; a subset of five subjects used Fidelity120 for three additional months after the main study. Speech perception was assessed for the spectral cues related to vowel F1 frequency, vowel F2 frequency, and consonant place of articulation; overall transmitted information for vowels and consonants; and sentence recognition in noise. Place-pitch sensitivity was measured for electrode pairs in the apical, middle, and basal regions of the implanted array using a psychophysical pitch-ranking task. With one exception, there was no effect of strategy (HiRes versus Fidelity120) on the speech measures tested, either during the main study (N = 10) or after extended use of Fidelity120 (N = 5). The exception was a small but significant advantage for HiRes over Fidelity120 for consonant perception during the main study. Examination of individual subjects' data revealed that 3 of 10 subjects demonstrated improved perception of one or more spectral cues with Fidelity120 relative to HiRes after 8 wks or longer experience with Fidelity120. Another three subjects exhibited initial decrements in spectral cue perception with Fidelity120 at the 8-wk time point; however, evidence from one subject suggested that such decrements may resolve with additional experience. Place-pitch thresholds were inversely related to improvements in vowel F2 frequency perception with Fidelity120 relative to HiRes. However, no relationship was observed between place-pitch thresholds and the other spectral measures (vowel F1 frequency or consonant place of articulation). Findings suggest that Fidelity120 supports small improvements in the perception of spectral speech cues in some Advanced Bionics CI users; however, many users show no clear benefit. Benefits are more likely to occur for vowel spectral cues (related to F1 and F2 frequency) than for consonant spectral cues (related to place of articulation). There was an inconsistent relationship between place-pitch sensitivity and improvements in spectral cue perception with Fidelity120 relative to HiRes. This may partly reflect the small number of sites at which place-pitch thresholds were measured. Contrary to some previous reports, there was no clear evidence that Fidelity120 supports improved sentence recognition in noise.

Pitch perception and production in congenital amusia: Evidence from Cantonese speakers.

PubMed

Liu, Fang; Chan, Alice H D; Ciocca, Valter; Roquet, Catherine; Peretz, Isabelle; Wong, Patrick C M

2016-07-01

This study investigated pitch perception and production in speech and music in individuals with congenital amusia (a disorder of musical pitch processing) who are native speakers of Cantonese, a tone language with a highly complex tonal system. Sixteen Cantonese-speaking congenital amusics and 16 controls performed a set of lexical tone perception, production, singing, and psychophysical pitch threshold tasks. Their tone production accuracy and singing proficiency were subsequently judged by independent listeners, and subjected to acoustic analyses. Relative to controls, amusics showed impaired discrimination of lexical tones in both speech and non-speech conditions. They also received lower ratings for singing proficiency, producing larger pitch interval deviations and making more pitch interval errors compared to controls. Demonstrating higher pitch direction identification thresholds than controls for both speech syllables and piano tones, amusics nevertheless produced native lexical tones with comparable pitch trajectories and intelligibility as controls. Significant correlations were found between pitch threshold and lexical tone perception, music perception and production, but not between lexical tone perception and production for amusics. These findings provide further evidence that congenital amusia is a domain-general language-independent pitch-processing deficit that is associated with severely impaired music perception and production, mildly impaired speech perception, and largely intact speech production.

Pitch perception and production in congenital amusia: Evidence from Cantonese speakers

PubMed Central

Liu, Fang; Chan, Alice H. D.; Ciocca, Valter; Roquet, Catherine; Peretz, Isabelle; Wong, Patrick C. M.

2016-01-01

This study investigated pitch perception and production in speech and music in individuals with congenital amusia (a disorder of musical pitch processing) who are native speakers of Cantonese, a tone language with a highly complex tonal system. Sixteen Cantonese-speaking congenital amusics and 16 controls performed a set of lexical tone perception, production, singing, and psychophysical pitch threshold tasks. Their tone production accuracy and singing proficiency were subsequently judged by independent listeners, and subjected to acoustic analyses. Relative to controls, amusics showed impaired discrimination of lexical tones in both speech and non-speech conditions. They also received lower ratings for singing proficiency, producing larger pitch interval deviations and making more pitch interval errors compared to controls. Demonstrating higher pitch direction identification thresholds than controls for both speech syllables and piano tones, amusics nevertheless produced native lexical tones with comparable pitch trajectories and intelligibility as controls. Significant correlations were found between pitch threshold and lexical tone perception, music perception and production, but not between lexical tone perception and production for amusics. These findings provide further evidence that congenital amusia is a domain-general language-independent pitch-processing deficit that is associated with severely impaired music perception and production, mildly impaired speech perception, and largely intact speech production. PMID:27475178

Differences in Taste Perception and Spicy Preference: A Thai-Japanese Cross-cultural Study.

PubMed

Trachootham, Dunyaporn; Satoh-Kuriwada, Shizuko; Lam-Ubol, Aroonwan; Promkam, Chadamas; Chotechuang, Nattida; Sasano, Takashi; Shoji, Noriaki

2017-12-25

Taste perception is influenced by several factors. However, the relation between taste perception and food culture is unclear. This study compared taste thresholds between populations with different food culture, i.e. Thai and Japanese. A matched case-control study was conducted in 168 adults (84 for each; aged between 50 and 90 years). The age, sex, systemic disease, medication, smoking, xerostomia, and oral hygiene of both groups were not different. Recognition thresholds (RTs) of sweet, salty, sour, bitter, and umami were measured using filter paper disc (FPD). Detection taste thresholds were measured using electrogustometry. Spicy preference was measured by calibrated questionnaires. Higher RTs of all tastes and higher detection taste thresholds were found in Thai as compared to those of Japanese (P < 0.0001). Separate analyses of healthy and unhealthy persons confirmed the significant differences between 2 countries. The average thresholds for sweet, salty, sour, and bitter in Thai and Japanese were 4 and 2, respectively. The average threshold for umami in Thai and Japanese was 5 and 3, respectively. Moreover, Thai population had stronger preference for spicy food (P < 0.0001) with 70% mild- or moderate and 10% strong lovers, compared to over 90% non- or mild-spicy lovers in Japanese. In addition, 70% of Thai consumed spicy food weekly, whilst 80% of Japanese consumed it monthly. Our findings suggested that population with stronger spicy preference such as Thai had much poorer taste sensitivity and perception than that with milder preference like Japanese. Extensive international survey is needed to conclude the influence of food culture on taste perception. © The Author(s) 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Effect of acute stress on taste perception: in relation with baseline anxiety level and body weight.

PubMed

Ileri-Gurel, Esin; Pehlivanoglu, Bilge; Dogan, Murat

2013-01-01

We aimed to determine the effect of acute stress on taste perception and its modulation in relation to body weight and baseline anxiety in this study. The anxiety of the participants, randomly allocated to stress (n = 35) or control (n = 16) groups, was assessed by State Trait Anxiety Inventory. Stroop color-word interference and cold pressor tests were applied as stress protocol. Glucose and salt taste detection thresholds were evaluated before and after the stress protocol in the stress group and corresponding times in the control group. Stress protocol increased heart rate and blood pressure as an indicator of stress system activation. Following stress glucose and salt thresholds decreased in the stress group, unchanged in the control group. Prestress salt thresholds were positively and decrements in salt thresholds were negatively correlated with trait anxiety scores of participants. The state anxiety levels of stress group positively correlated with the decrease in glucose thresholds. Waist-to-hip ratio was negatively correlated with prestress salt thresholds of the subjects. Our results revealed that thresholds for sweet and salty tastes are modulated during stressful conditions. Our data also demonstrated a relationship between taste perception and baseline anxiety levels of healthy individuals, which may be important to understand the appetite alterations in individuals under stressful conditions.

Whole body vibration training improves vibration perception threshold in healthy young adults: A randomized clinical trial pilot study

PubMed Central

Hernandez-Mocholi, M.A.; Dominguez-Muñoz, F.J.; Corzo, H.; Silva, S.C.S.; Adsuar, J.C.; Gusi, N.

2016-01-01

Objectives: Loss of foot sensitivity is a relevant parameter to assess and prevent in several diseases. It is crucial to determine the vibro-tactile sensitivity threshold response to acute conditions to explore innovative monitor tools and interventions to prevent and treat this challenge. The aims were: 1) to analyze the acute effects of a single whole body vibration session (4min-18Hz-4mm) on vibro-tactile perception threshold in healthy young adults. 2) to analyze the 48 hours effects of 3 whole body vibration sessions on vibro-tactile perception threshold in healthy young adults. Methods: A randomized controlled clinical trial over 3 sessions of whole body vibration intervention or 3 sessions of placebo intervention. Twenty-eight healthy young adults were included: 11 experimental group and 12 placebo group. The experimental group performed 3 sessions of WBV while the placebo group performed 3 sessions of placebo intervention. Results: The vibro-tactile threshold increased right after a single WBV session in comparison with placebo. Nevertheless, after 3 whole body vibration sessions and 48 hours, the threshold decreased to values lower than the initial. Conclusions: The acute response of the vibro-tactile threshold to one whole body vibration session increased, but the 48 hours short-term response of this threshold decreased in healthy young adults. PMID:26944818

Structural Health Monitoring: Leveraging Pain in the Human Body

NASA Astrophysics Data System (ADS)

Nayak, Subhadarshi

2012-07-01

Tissue damage, or the perception thereof, is managed through pain experience. The neurobiological process of pain triggers most effective defense mechanisms for our safety. Structural health monitoring (SHM) is also a very similar function, albeit in engineering systems. SHM technology can leverage many aspects of pain mechanisms to progress in several critical areas. Discrimination between features from the undamaged and damaged structures can follow the threshold gate mechanism of the pain perception. Furthermore, the sensing mechanisms can be adaptive to changes by adjusting the threshold as does the pain perception. A distributed sensor network, often advanced by SHM, can be made fault-tolerant and robust by following the perception way of self-organization and redundancy. Data handling in real life is a huge challenge for large-scale SHM. As sensory data of pain is first cleaned, the threshold is then processed through experiential information gathering and use.

Agreeable Smellers and Sensitive Neurotics – Correlations among Personality Traits and Sensory Thresholds

PubMed Central

Croy, Ilona; Springborn, Maria; Lötsch, Jörn; Johnston, Amy N. B.; Hummel, Thomas

2011-01-01

Correlations between personality traits and a wide range of sensory thresholds were examined. Participants (N = 124) completed a personality inventory (NEO-FFI) and underwent assessment of olfactory, trigeminal, tactile and gustatory detection thresholds, as well as examination of trigeminal and tactile pain thresholds. Significantly enhanced odor sensitivity in socially agreeable people, significantly enhanced trigeminal sensitivity in neurotic subjects, and a tendency for enhanced pain tolerance in highly conscientious participants was revealed. It is postulated that varied sensory processing may influence an individual's perception of the environment; particularly their perception of socially relevant or potentially dangerous stimuli and thus, varied with personality. PMID:21556139

Agreeable smellers and sensitive neurotics--correlations among personality traits and sensory thresholds.

PubMed

Croy, Ilona; Springborn, Maria; Lötsch, Jörn; Johnston, Amy N B; Hummel, Thomas

2011-04-27

Correlations between personality traits and a wide range of sensory thresholds were examined. Participants (N = 124) completed a personality inventory (NEO-FFI) and underwent assessment of olfactory, trigeminal, tactile and gustatory detection thresholds, as well as examination of trigeminal and tactile pain thresholds. Significantly enhanced odor sensitivity in socially agreeable people, significantly enhanced trigeminal sensitivity in neurotic subjects, and a tendency for enhanced pain tolerance in highly conscientious participants was revealed. It is postulated that varied sensory processing may influence an individual's perception of the environment; particularly their perception of socially relevant or potentially dangerous stimuli and thus, varied with personality.

Relationship between pastoralists' evaluation of rangeland state and vegetation threshold changes in Mongolian rangelands.

PubMed

Kakinuma, Kaoru; Sasaki, Takehiro; Jamsran, Undarmaa; Okuro, Toshiya; Takeuchi, Kazuhiko

2014-10-01

Applying the threshold concept to rangeland management is an important challenge in semi-arid and arid regions. Threshold recognition and prediction is necessary to enable local pastoralists to prevent the occurrence of an undesirable state that would result from unsustainable grazing pressure, but this requires a better understanding of the pastoralists' perception of vegetation threshold changes. We estimated plant species cover in survey plots along grazing gradients in steppe and desert-steppe areas of Mongolia. We also conducted interviews with local pastoralists and asked them to evaluate whether the plots were suitable for grazing. Floristic composition changed nonlinearly along the grazing gradient in both the desert-steppe and steppe areas. Pastoralists observed the floristic composition changes along the grazing gradients, but their evaluations of grazing suitability did not always decrease along the grazing gradients, both of which included areas in a post-threshold state. These results indicated that local pastoralists and scientists may have different perceptions of vegetation states, even though both of groups used plant species and coverage as indicators in their evaluations. Therefore, in future studies of rangeland management, researchers and pastoralists should exchange their knowledge and perceptions to successfully apply the threshold concept to rangeland management.

Oxygenated-Blood Colour Change Thresholds for Perceived Facial Redness, Health, and Attractiveness

PubMed Central

Re, Daniel E.; Whitehead, Ross D.; Xiao, Dengke; Perrett, David I.

2011-01-01

Blood oxygenation level is associated with cardiovascular fitness, and raising oxygenated blood colouration in human faces increases perceived health. The current study used a two-alternative forced choice (2AFC) psychophysics design to quantify the oxygenated blood colour (redness) change threshold required to affect perception of facial colour, health and attractiveness. Detection thresholds for colour judgments were lower than those for health and attractiveness, which did not differ. The results suggest redness preferences do not reflect a sensory bias, rather preferences may be based on accurate indications of health status. Furthermore, results suggest perceived health and attractiveness may be perceptually equivalent when they are assessed based on facial redness. Appearance-based motivation for lifestyle change can be effective; thus future studies could assess the degree to which cardiovascular fitness increases face redness and could quantify changes in aerobic exercise needed to increase facial attractiveness. PMID:21448270

Oxygenated-blood colour change thresholds for perceived facial redness, health, and attractiveness.

PubMed

Re, Daniel E; Whitehead, Ross D; Xiao, Dengke; Perrett, David I

2011-03-23

Blood oxygenation level is associated with cardiovascular fitness, and raising oxygenated blood colouration in human faces increases perceived health. The current study used a two-alternative forced choice (2AFC) psychophysics design to quantify the oxygenated blood colour (redness) change threshold required to affect perception of facial colour, health and attractiveness. Detection thresholds for colour judgments were lower than those for health and attractiveness, which did not differ. The results suggest redness preferences do not reflect a sensory bias, rather preferences may be based on accurate indications of health status. Furthermore, results suggest perceived health and attractiveness may be perceptually equivalent when they are assessed based on facial redness. Appearance-based motivation for lifestyle change can be effective; thus future studies could assess the degree to which cardiovascular fitness increases face redness and could quantify changes in aerobic exercise needed to increase facial attractiveness.

Improving Speech Perception in Noise with Current Focusing in Cochlear Implant Users

PubMed Central

Srinivasan, Arthi G.; Padilla, Monica; Shannon, Robert V.; Landsberger, David M.

2013-01-01

Cochlear implant (CI) users typically have excellent speech recognition in quiet but struggle with understanding speech in noise. It is thought that broad current spread from stimulating electrodes causes adjacent electrodes to activate overlapping populations of neurons which results in interactions across adjacent channels. Current focusing has been studied as a way to reduce spread of excitation, and therefore, reduce channel interactions. In particular, partial tripolar stimulation has been shown to reduce spread of excitation relative to monopolar stimulation. However, the crucial question is whether this benefit translates to improvements in speech perception. In this study, we compared speech perception in noise with experimental monopolar and partial tripolar speech processing strategies. The two strategies were matched in terms of number of active electrodes, microphone, filterbanks, stimulation rate and loudness (although both strategies used a lower stimulation rate than typical clinical strategies). The results of this study showed a significant improvement in speech perception in noise with partial tripolar stimulation. All subjects benefited from the current focused speech processing strategy. There was a mean improvement in speech recognition threshold of 2.7 dB in a digits in noise task and a mean improvement of 3 dB in a sentences in noise task with partial tripolar stimulation relative to monopolar stimulation. Although the experimental monopolar strategy was worse than the clinical, presumably due to different microphones, frequency allocations and stimulation rates, the experimental partial-tripolar strategy, which had the same changes, showed no acute deficit relative to the clinical. PMID:23467170

Effect of Pulse Polarity on Thresholds and on Non-monotonic Loudness Growth in Cochlear Implant Users.

PubMed

Macherey, Olivier; Carlyon, Robert P; Chatron, Jacques; Roman, Stéphane

2017-06-01

Most cochlear implants (CIs) activate their electrodes non-simultaneously in order to eliminate electrical field interactions. However, the membrane of auditory nerve fibers needs time to return to its resting state, causing the probability of firing to a pulse to be affected by previous pulses. Here, we provide new evidence on the effect of pulse polarity and current level on these interactions. In experiment 1, detection thresholds and most comfortable levels (MCLs) were measured in CI users for 100-Hz pulse trains consisting of two consecutive biphasic pulses of the same or of opposite polarity. All combinations of polarities were studied: anodic-cathodic-anodic-cathodic (ACAC), CACA, ACCA, and CAAC. Thresholds were lower when the adjacent phases of the two pulses had the same polarity (ACCA and CAAC) than when they were different (ACAC and CACA). Some subjects showed a lower threshold for ACCA than for CAAC while others showed the opposite trend demonstrating that polarity sensitivity at threshold is genuine and subject- or electrode-dependent. In contrast, anodic (CAAC) pulses always showed a lower MCL than cathodic (ACCA) pulses, confirming previous reports. In experiments 2 and 3, the subjects compared the loudness of several pulse trains differing in current level separately for ACCA and CAAC. For 40 % of the electrodes tested, loudness grew non-monotonically as a function of current level for ACCA but never for CAAC. This finding may relate to a conduction block of the action potentials along the fibers induced by a strong hyperpolarization of their central processes. Further analysis showed that the electrodes showing a lower threshold for ACCA than for CAAC were more likely to yield a non-monotonic loudness growth. It is proposed that polarity sensitivity at threshold reflects the local neural health and that anodic asymmetric pulses should preferably be used to convey sound information while avoiding abnormal loudness percepts.

Threshold Capability Development in Intensive Mode Business Units

ERIC Educational Resources Information Center

Crispin, Stuart; Hancock, Phil; Male, Sally Amanda; Baillie, Caroline; MacNish, Cara; Leggoe, Jeremy; Ranmuthugala, Dev; Alam, Firoz

2016-01-01

Purpose: The purpose of this paper is to explore: student perceptions of threshold concepts and capabilities in postgraduate business education, and the potential impacts of intensive modes of teaching on student understanding of threshold concepts and development of threshold capabilities. Design/Methodology/Approach: The student experience of…

Thermal sensation and climate: a comparison of UTCI and PET thresholds in different climates

NASA Astrophysics Data System (ADS)

Pantavou, Katerina; Lykoudis, Spyridon; Nikolopoulou, Marialena; Tsiros, Ioannis X.

2018-06-01

The influence of physiological acclimatization and psychological adaptation on thermal perception is well documented and has revealed the importance of thermal experience and expectation in the evaluation of environmental stimuli. Seasonal patterns of thermal perception have been studied, and calibrated thermal indices' scales have been proposed to obtain meaningful interpretations of thermal sensation indices in different climate regions. The current work attempts to quantify the contribution of climate to the long-term thermal adaptation by examining the relationship between climate normal annual air temperature (1971-2000) and such climate-calibrated thermal indices' assessment scales. The thermal sensation ranges of two thermal indices, the Universal Thermal Climate Index (UTCI) and the Physiological Equivalent Temperature Index (PET), were calibrated for three warm temperate climate contexts (Cfa, Cfb, Csa), against the subjective evaluation of the thermal environment indicated by interviewees during field surveys conducted at seven European cities: Athens (GR), Thessaloniki (GR), Milan (IT), Fribourg (CH), Kassel (DE), Cambridge (UK), and Sheffield (UK), under the same research protocol. Then, calibrated scales for other climate contexts were added from the literature, and the relationship between the respective scales' thresholds and climate normal annual air temperature was examined. To maintain the maximum possible comparability, three methods were applied for the calibration, namely linear, ordinal, and probit regression. The results indicated that the calibrated UTCI and PET thresholds increase with the climate normal annual air temperature of the survey city. To investigate further climates, we also included in the analysis results of previous studies presenting only thresholds for neutral thermal sensation. The average increase of the respective thresholds in the case of neutral thermal sensation was about 0.6 °C for each 1 °C increase of the normal annual air temperature for both indices, statistically significant only for PET though.

Spatial and temporal characteristics of V1 microstimulation during chronic implantation of a microelectrode array in a behaving macaque

NASA Astrophysics Data System (ADS)

Davis, T. S.; Parker, R. A.; House, P. A.; Bagley, E.; Wendelken, S.; Normann, R. A.; Greger, B.

2012-12-01

Objective. It has been hypothesized that a vision prosthesis capable of evoking useful visual percepts can be based upon electrically stimulating the primary visual cortex (V1) of a blind human subject via penetrating microelectrode arrays. As a continuation of earlier work, we examined several spatial and temporal characteristics of V1 microstimulation. Approach. An array of 100 penetrating microelectrodes was chronically implanted in V1 of a behaving macaque monkey. Microstimulation thresholds were measured using a two-alternative forced choice detection task. Relative locations of electrically-evoked percepts were measured using a memory saccade-to-target task. Main results. The principal finding was that two years after implantation we were able to evoke behavioural responses to electric stimulation across the spatial extent of the array using groups of contiguous electrodes. Consistent responses to stimulation were evoked at an average threshold current per electrode of 204 ± 49 µA (mean ± std) for groups of four electrodes and 91 ± 25 µA for groups of nine electrodes. Saccades to electrically-evoked percepts using groups of nine electrodes showed that the animal could discriminate spatially distinct percepts with groups having an average separation of 1.6 ± 0.3 mm (mean ± std) in cortex and 1.0° ± 0.2° in visual space. Significance. These results demonstrate chronic perceptual functionality and provide evidence for the feasibility of a cortically-based vision prosthesis for the blind using penetrating microelectrodes.

Intensity coding in electric hearing: Effects of electrode configurations and stimulation waveforms

PubMed Central

Chua, Tiffany Elise H.; Bachman, Mark; Zeng, Fan-Gang

2011-01-01

Objectives Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception, but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem. Design The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were 5 Clarion cochlear implant users. For each subject, data from apical, middle and basal electrode positions were collected when possible. Results Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels. Conclusions The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings, nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen. PMID:21610498

Children's perceptions of smile esthetics and their influence on social judgment.

PubMed

Rossini, Gabriele; Parrini, Simone; Castroflorio, Tommaso; Fortini, Arturo; Deregibus, Andrea; Debernardi, Cesare L

2016-11-01

To define a threshold of acceptance of smile esthetics for children and adolescents. A systematic search in the medical literature (PubMed, PubMed Central, National Library of Medicine's Medline, Embase, Cochrane Central Register of Controlled Clinical Trials, Web of Knowledge, Scopus, Google Scholar, and LILACs) was performed to identify all peer-reviewed papers reporting data regarding the evaluation of children's and adolescents' perceptions of dental esthetic factors. The search was conducted using a research strategy based on keywords such as "children," "adolescents," "smile aesthetics perception," "smile aesthetics evaluation." Studies analyzing smile esthetics involving at least 10 observers younger than 18 years of age were selected. Among the 1667 analyzed articles, five studies were selected for the final review process. No study included in the review analyzed perception of smile anomalies in a quantitative or qualitative way, thus no threshold was identified for smile features. Among the analyzed samples, unaltered smiles were always significantly associated with better evaluation scores when compared with altered smiles. Smile esthetics influence social perception during childhood and adolescence. However, thresholds of smile esthetic acceptance in children and adolescents are still not available.

Multiple Fingers - One Gestalt.

PubMed

Lezkan, Alexandra; Manuel, Steven G; Colgate, J Edward; Klatzky, Roberta L; Peshkin, Michael A; Drewing, Knut

2016-01-01

The Gestalt theory of perception offered principles by which distributed visual sensations are combined into a structured experience ("Gestalt"). We demonstrate conditions whereby haptic sensations at two fingertips are integrated in the perception of a single object. When virtual bumps were presented simultaneously to the right hand's thumb and index finger during lateral arm movements, participants reported perceiving a single bump. A discrimination task measured the bump's perceived location and perceptual reliability (assessed by differential thresholds) for four finger configurations, which varied in their adherence to the Gestalt principles of proximity (small versus large finger separation) and synchrony (virtual spring to link movements of the two fingers versus no spring). According to models of integration, reliability should increase with the degree to which multi-finger cues integrate into a unified percept. Differential thresholds were smaller in the virtual-spring condition (synchrony) than when fingers were unlinked. Additionally, in the condition with reduced synchrony, greater proximity led to lower differential thresholds. Thus, with greater adherence to Gestalt principles, thresholds approached values predicted for optimal integration. We conclude that the Gestalt principles of synchrony and proximity apply to haptic perception of surface properties and that these principles can interact to promote multi-finger integration.

Is the introduction of another variable to the strength-duration curve necessary in neurostimulation?

PubMed

Abejón, David; Rueda, Pablo; del Saz, Javier; Arango, Sara; Monzón, Eva; Gilsanz, Fernando

2015-04-01

Neurostimulation is the process and technology derived from the application of electricity with different parameters to activate or inhibit nerve pathways. Pulse width (Pw) is the duration of each electrical impulse and, along with amplitude (I), determines the total energy charge of the stimulation. The aim of the study was to test Pw values to find the most adequate pulse widths in rechargeable systems to obtain the largest coverage of the painful area, the most comfortable paresthesia, and the greatest patient satisfaction. A study of the parameters was performed, varying Pw while maintaining a fixed frequency at 50 Hz. Data on perception threshold (Tp ), discomfort threshold (Td ), and therapeutic threshold (Tt ) were recorded, applying 14 increasing Pw values ranging from 50 µsec to 1000 µsec. Lastly, the behavior of the therapeutic range (TR), the coverage of the painful area, the subjective patient perception of paresthesia, and the degree of patient satisfaction were assessed. The findings after analyzing the different thresholds were as follows: When varying the Pw, the differences obtained at each threshold (Tp , Tt , and Td ) were statistically significant (p < 0.05). The differences among the resulting Tp values and among the resulting Tt values were statistically significant when varying Pw from 50 up to 600 µsec (p < 0.05). For Pw levels 600 µsec and up, no differences were observed in these thresholds. In the case of Td , significant differences existed as Pw increased from 50 to 700 µsec (p ≤ 0.05). The coverage increased in a statistically significant way (p < 0.05) from Pw values of 50 µsec to 300 µsec. Good or very good subjective perception was shown at about Pw 300 µsec. The patient paresthesia coverage was introduced as an extra variable in the chronaxie-rheobase curve, allowing the adjustment of Pw values for optimal programming. The coverage of the patient against the current chronaxie-rheobase formula will be represented on three axes; an extra axis (z) will appear, multiplying each combination of Pw value and amplitude by the percentage of coverage corresponding to those values. Using this new comparison of chronaxie-rheobase curve vs. coverage, maximum Pw values will be obtained different from those obtained by classic methods. © 2014 International Neuromodulation Society.

Endogenous modulation of human visual cortex activity improves perception at twilight.

PubMed

Cordani, Lorenzo; Tagliazucchi, Enzo; Vetter, Céline; Hassemer, Christian; Roenneberg, Till; Stehle, Jörg H; Kell, Christian A

2018-04-10

Perception, particularly in the visual domain, is drastically influenced by rhythmic changes in ambient lighting conditions. Anticipation of daylight changes by the circadian system is critical for survival. However, the neural bases of time-of-day-dependent modulation in human perception are not yet understood. We used fMRI to study brain dynamics during resting-state and close-to-threshold visual perception repeatedly at six times of the day. Here we report that resting-state signal variance drops endogenously at times coinciding with dawn and dusk, notably in sensory cortices only. In parallel, perception-related signal variance in visual cortices decreases and correlates negatively with detection performance, identifying an anticipatory mechanism that compensates for the deteriorated visual signal quality at dawn and dusk. Generally, our findings imply that decreases in spontaneous neural activity improve close-to-threshold perception.

Evidence for an All-Or-None Perceptual Response: Single-Trial Analyses of Magnetoencephalography Signals Indicate an Abrupt Transition Between Visual Perception and Its Absence

PubMed Central

Sekar, Krithiga; Findley, William M.; Llinás, Rodolfo R.

2014-01-01

Whether consciousness is an all-or-none or graded phenomenon is an area of inquiry that has received considerable interest in neuroscience and is as of yet, still debated. In this magnetoencephalography (MEG) study we used a single stimulus paradigm with sub-threshold, threshold and supra-threshold duration inputs to assess whether stimulus perception is continuous with or abruptly differentiated from unconscious stimulus processing in the brain. By grouping epochs according to stimulus identification accuracy and exposure duration, we were able to investigate whether a high-amplitude perception-related cortical event was (1) only evoked for conditions where perception was most probable (2) had invariant amplitude once evoked and (3) was largely absent for conditions where perception was least probable (criteria satisfying an all-on-none hypothesis). We found that averaged evoked responses showed a gradual increase in amplitude with increasing perceptual strength. However, single trial analyses demonstrated that stimulus perception was correlated with an all-or-none response, the temporal precision of which increased systematically as perception transitioned from ambiguous to robust states. Due to poor signal-to-noise resolution of single trial data, whether perception-related responses, whenever present, were invariant in amplitude could not be unambiguously demonstrated. However, our findings strongly suggest that visual perception of simple stimuli is associated with an all-or-none cortical evoked response the temporal precision of which varies as a function of perceptual strength. PMID:22020091

Age effects on pain thresholds, temporal summation and spatial summation of heat and pressure pain.

PubMed

Lautenbacher, Stefan; Kunz, Miriam; Strate, Peter; Nielsen, Jesper; Arendt-Nielsen, Lars

2005-06-01

Experimental data on age-related changes in pain perception have so far been contradictory. It has appeared that the type of pain induction method is critical in this context, with sensitivity to heat pain being decreased whereas sensitivity to pressure pain may be even enhanced in the elderly. Furthermore, it has been shown that temporal summation of heat pain is more pronounced in the elderly but it has remained unclear whether age differences in temporal summation are also evident when using other pain induction methods. No studies on age-related changes in spatial summation of pain have so far been conducted. The aim of the present study was to provide a comprehensive survey on age-related changes in pain perception, i.e. in somatosensory thresholds (warmth, cold, vibration), pain thresholds (heat, pressure) and spatial and temporal summation of heat and pressure pain. We investigated 20 young (mean age 27.1 years) and 20 elderly (mean age 71.6 years) subjects. Our results confirmed and extended previous findings by showing that somatosensory thresholds for non-noxious stimuli increase with age whereas pressure pain thresholds decrease and heat pain thresholds show no age-related changes. Apart from an enhanced temporal summation of heat pain, pain summation was not found to be critically affected by age. The results of the present study provide evidence for stimulus-specific changes in pain perception in the elderly, with deep tissue (muscle) nociception being affected differently by age than superficial tissue (skin) nociception. Summation mechanisms contribute only moderately to age changes in pain perception.

Neural correlates of coherent and biological motion perception in autism.

PubMed

Koldewyn, Kami; Whitney, David; Rivera, Susan M

2011-09-01

Recent evidence suggests those with autism may be generally impaired in visual motion perception. To examine this, we investigated both coherent and biological motion processing in adolescents with autism employing both psychophysical and fMRI methods. Those with autism performed as well as matched controls during coherent motion perception but had significantly higher thresholds for biological motion perception. The autism group showed reduced posterior Superior Temporal Sulcus (pSTS), parietal and frontal activity during a biological motion task while showing similar levels of activity in MT+/V5 during both coherent and biological motion trials. Activity in MT+/V5 was predictive of individual coherent motion thresholds in both groups. Activity in dorsolateral prefrontal cortex (DLPFC) and pSTS was predictive of biological motion thresholds in control participants but not in those with autism. Notably, however, activity in DLPFC was negatively related to autism symptom severity. These results suggest that impairments in higher-order social or attentional networks may underlie visual motion deficits observed in autism. © 2011 Blackwell Publishing Ltd.

Neural correlates of coherent and biological motion perception in autism

PubMed Central

Koldewyn, Kami; Whitney, David; Rivera, Susan M.

2011-01-01

Recent evidence suggests those with autism may be generally impaired in visual motion perception. To examine this, we investigated both coherent and biological motion processing in adolescents with autism employing both psychophysical and fMRI methods. Those with autism performed as well as matched controls during coherent motion perception but had significantly higher thresholds for biological motion perception. The autism group showed reduced posterior Superior Temporal Sulcus (pSTS), parietal and frontal activity during a biological motion task while showing similar levels of activity in MT+/V5 during both coherent and biological motion trials. Activity in MT+/V5 was predictive of individual coherent motion thresholds in both groups. Activity in dorsolateral prefrontal cortex (DLPFC) and pSTS was predictive of biological motion thresholds in control participants but not in those with autism. Notably, however, activity in DLPFC was negatively related to autism symptom severity. These results suggest that impairments in higher-order social or attentional networks may underlie visual motion deficits observed in autism. PMID:21884323

Long-Lasting Enhancement of Visual Perception with Repetitive Noninvasive Transcranial Direct Current Stimulation

PubMed Central

Behrens, Janina R.; Kraft, Antje; Irlbacher, Kerstin; Gerhardt, Holger; Olma, Manuel C.; Brandt, Stephan A.

2017-01-01

Understanding processes performed by an intact visual cortex as the basis for developing methods that enhance or restore visual perception is of great interest to both researchers and medical practitioners. Here, we explore whether contrast sensitivity, a main function of the primary visual cortex (V1), can be improved in healthy subjects by repetitive, noninvasive anodal transcranial direct current stimulation (tDCS). Contrast perception was measured via threshold perimetry directly before and after intervention (tDCS or sham stimulation) on each day over 5 consecutive days (24 subjects, double-blind study). tDCS improved contrast sensitivity from the second day onwards, with significant effects lasting 24 h. After the last stimulation on day 5, the anodal group showed a significantly greater improvement in contrast perception than the sham group (23 vs. 5%). We found significant long-term effects in only the central 2–4° of the visual field 4 weeks after the last stimulation. We suspect a combination of two factors contributes to these lasting effects. First, the V1 area that represents the central retina was located closer to the polarization electrode, resulting in higher current density. Second, the central visual field is represented by a larger cortical area relative to the peripheral visual field (cortical magnification). This is the first study showing that tDCS over V1 enhances contrast perception in healthy subjects for several weeks. This study contributes to the investigation of the causal relationship between the external modulation of neuronal membrane potential and behavior (in our case, visual perception). Because the vast majority of human studies only show temporary effects after single tDCS sessions targeting the visual system, our study underpins the potential for lasting effects of repetitive tDCS-induced modulation of neuronal excitability. PMID:28860969

Objective Assessment of Spectral Ripple Discrimination in Cochlear Implant Listeners Using Cortical Evoked Responses to an Oddball Paradigm

PubMed Central

Lopez Valdes, Alejandro; Mc Laughlin, Myles; Viani, Laura; Walshe, Peter; Smith, Jaclyn; Zeng, Fan-Gang; Reilly, Richard B.

2014-01-01

Cochlear implants (CIs) can partially restore functional hearing in deaf individuals. However, multiple factors affect CI listener's speech perception, resulting in large performance differences. Non-speech based tests, such as spectral ripple discrimination, measure acoustic processing capabilities that are highly correlated with speech perception. Currently spectral ripple discrimination is measured using standard psychoacoustic methods, which require attentive listening and active response that can be difficult or even impossible in special patient populations. Here, a completely objective cortical evoked potential based method is developed and validated to assess spectral ripple discrimination in CI listeners. In 19 CI listeners, using an oddball paradigm, cortical evoked potential responses to standard and inverted spectrally rippled stimuli were measured. In the same subjects, psychoacoustic spectral ripple discrimination thresholds were also measured. A neural discrimination threshold was determined by systematically increasing the number of ripples per octave and determining the point at which there was no longer a significant difference between the evoked potential response to the standard and inverted stimuli. A correlation was found between the neural and the psychoacoustic discrimination thresholds (R2 = 0.60, p<0.01). This method can objectively assess CI spectral resolution performance, providing a potential tool for the evaluation and follow-up of CI listeners who have difficulty performing psychoacoustic tests, such as pediatric or new users. PMID:24599314

Revealing and quantifying the impaired phonological analysis underpinning impaired comprehension in Wernicke's aphasia.

PubMed

Robson, Holly; Keidel, James L; Ralph, Matthew A Lambon; Sage, Karen

2012-01-01

Wernicke's aphasia is a condition which results in severely disrupted language comprehension following a lesion to the left temporo-parietal region. A phonological analysis deficit has traditionally been held to be at the root of the comprehension impairment in Wernicke's aphasia, a view consistent with current functional neuroimaging which finds areas in the superior temporal cortex responsive to phonological stimuli. However behavioural evidence to support the link between a phonological analysis deficit and auditory comprehension has not been yet shown. This study extends seminal work by Blumstein, Baker, and Goodglass (1977) to investigate the relationship between acoustic-phonological perception, measured through phonological discrimination, and auditory comprehension in a case series of Wernicke's aphasia participants. A novel adaptive phonological discrimination task was used to obtain reliable thresholds of the phonological perceptual distance required between nonwords before they could be discriminated. Wernicke's aphasia participants showed significantly elevated thresholds compared to age and hearing matched control participants. Acoustic-phonological thresholds correlated strongly with auditory comprehension abilities in Wernicke's aphasia. In contrast, nonverbal semantic skills showed no relationship with auditory comprehension. The results are evaluated in the context of recent neurobiological models of language and suggest that impaired acoustic-phonological perception underlies the comprehension impairment in Wernicke's aphasia and favour models of language which propose a leftward asymmetry in phonological analysis. Copyright © 2011 Elsevier Ltd. All rights reserved.

Objective assessment of spectral ripple discrimination in cochlear implant listeners using cortical evoked responses to an oddball paradigm.

PubMed

Lopez Valdes, Alejandro; Mc Laughlin, Myles; Viani, Laura; Walshe, Peter; Smith, Jaclyn; Zeng, Fan-Gang; Reilly, Richard B

2014-01-01

Cochlear implants (CIs) can partially restore functional hearing in deaf individuals. However, multiple factors affect CI listener's speech perception, resulting in large performance differences. Non-speech based tests, such as spectral ripple discrimination, measure acoustic processing capabilities that are highly correlated with speech perception. Currently spectral ripple discrimination is measured using standard psychoacoustic methods, which require attentive listening and active response that can be difficult or even impossible in special patient populations. Here, a completely objective cortical evoked potential based method is developed and validated to assess spectral ripple discrimination in CI listeners. In 19 CI listeners, using an oddball paradigm, cortical evoked potential responses to standard and inverted spectrally rippled stimuli were measured. In the same subjects, psychoacoustic spectral ripple discrimination thresholds were also measured. A neural discrimination threshold was determined by systematically increasing the number of ripples per octave and determining the point at which there was no longer a significant difference between the evoked potential response to the standard and inverted stimuli. A correlation was found between the neural and the psychoacoustic discrimination thresholds (R2=0.60, p<0.01). This method can objectively assess CI spectral resolution performance, providing a potential tool for the evaluation and follow-up of CI listeners who have difficulty performing psychoacoustic tests, such as pediatric or new users.

The Effects of Compensatory Auditory Stimulation and High-Definition Transcranial Direct Current Stimulation (HD-tDCS) on Tinnitus Perception - A Randomized Pilot Study.

PubMed

Henin, Simon; Fein, Dovid; Smouha, Eric; Parra, Lucas C

2016-01-01

Tinnitus correlates with elevated hearing thresholds and reduced cochlear compression. We hypothesized that reduced peripheral input leads to elevated neuronal gain resulting in the perception of a phantom sound. The purpose of this pilot study was to test whether compensating for this peripheral deficit could reduce the tinnitus percept acutely using customized auditory stimulation. To further enhance the effects of auditory stimulation, this intervention was paired with high-definition transcranial direct current stimulation (HD-tDCS). A randomized sham-controlled, single blind study was conducted in a clinical setting on adult participants with chronic tinnitus (n = 14). Compensatory auditory stimulation (CAS) and HD-tDCS were administered either individually or in combination in order to access the effects of both interventions on tinnitus perception. CAS consisted of sound exposure typical to daily living (20-minute sound-track of a TV show), which was adapted with compressive gain to compensate for deficits in each subject's individual audiograms. Minimum masking levels and the visual analog scale were used to assess the strength of the tinnitus percept immediately before and after the treatment intervention. CAS reduced minimum masking levels, and visual analog scale trended towards improvement. Effects of HD-tDCS could not be resolved with the current sample size. The results of this pilot study suggest that providing tailored auditory stimulation with frequency-specific gain and compression may alleviate tinnitus in a clinical population. Further experimentation with longer interventions is warranted in order to optimize effect sizes.

The phase of prestimulus alpha oscillations affects tactile perception.

PubMed

Ai, Lei; Ro, Tony

2014-03-01

Previous studies have shown that neural oscillations in the 8- to 12-Hz range influence sensory perception. In the current study, we examined whether both the power and phase of these mu/alpha oscillations predict successful conscious tactile perception. Near-threshold tactile stimuli were applied to the left hand while electroencephalographic (EEG) activity was recorded over the contralateral right somatosensory cortex. We found a significant inverted U-shaped relationship between prestimulus mu/alpha power and detection rate, suggesting that there is an intermediate level of alpha power that is optimal for tactile perception. We also found a significant difference in phase angle concentration at stimulus onset that predicted whether the upcoming tactile stimulus was perceived or missed. As has been shown in the visual system, these findings suggest that these mu/alpha oscillations measured over somatosensory areas exert a strong inhibitory control on tactile perception and that pulsed inhibition by these oscillations shapes the state of brain activity necessary for conscious perception. They further suggest that these common phasic processing mechanisms across different sensory modalities and brain regions may reflect a common underlying encoding principle in perceptual processing that leads to momentary windows of perceptual awareness.

Nociception at the diabetic foot, an uncharted territory

PubMed Central

Chantelau, Ernst A

2015-01-01

The diabetic foot is characterised by painless foot ulceration and/or arthropathy; it is a typical complication of painless diabetic neuropathy. Neuropathy depletes the foot skin of intraepidermal nerve fibre endings of the afferent A-delta and C-fibres, which are mostly nociceptors and excitable by noxious stimuli only. However, some of them are cold or warm receptors whose functions in diabetic neuropathy have frequently been reported. Hence, it is well established by quantitative sensory testing that thermal detection thresholds at the foot skin increase during the course of painless diabetic neuropathy. Pain perception (nociception), by contrast, has rarely been studied. Recent pilot studies of pinprick pain at plantar digital skinfolds showed that the perception threshold was always above the upper limit of measurement of 512 mN (equivalent to 51.2 g) at the diabetic foot. However, deep pressure pain perception threshold at musculus abductor hallucis was beyond 1400 kPa (equivalent to 14 kg; limit of measurement) only in every fifth case. These discrepancies of pain perception between forefoot and hindfoot, and between skin and muscle, demand further study. Measuring nociception at the feet in diabetes opens promising clinical perspectives. A critical nociception threshold may be quantified (probably corresponding to a critical number of intraepidermal nerve fibre endings), beyond which the individual risk of a diabetic foot rises appreciably. Staging of diabetic neuropathy according to nociception thresholds at the feet is highly desirable as guidance to an individualised injury prevention strategy. PMID:25897350

Effects of transcranial direct current stimulation of primary somatosensory cortex on vibrotactile detection and discrimination

PubMed Central

Labbé, Sara; Meftah, El-Mehdi

2016-01-01

Anodal transcranial direct current stimulation (a-tDCS) of primary somatosensory cortex (S1) has been shown to enhance tactile spatial acuity, but there is little information as to the underlying neuronal mechanisms. We examined vibrotactile perception on the distal phalanx of the middle finger before, during, and after contralateral S1 tDCS [a-, cathodal (c)-, and sham (s)-tDCS]. The experiments tested our shift-gain hypothesis, which predicted that a-tDCS would decrease vibrotactile detection and discrimination thresholds (leftward shift of the stimulus-response function with increased gain/slope) relative to s-tDCS, whereas c-tDCS would have the opposite effects (relative to s-tDCS). The results showed that weak a-tDCS (1 mA, 20 min) led to a reduction in both vibrotactile detection and discrimination thresholds to 73–76% of baseline during the application of the stimulation in subjects categorized as responders. These effects persisted after the end of a-tDCS but were absent 30 min later. Most, but not all, subjects showed a decrease in threshold (8/12 for detection; 9/12 for discrimination). Intersubject variability was explained by a ceiling effect in the discrimination task. c-tDCS had no significant effect on either detection or discrimination threshold. Taken together, our results supported our shift-gain hypothesis for a-tDCS but not c-tDCS. PMID:26864757

Improving speech perception in noise with current focusing in cochlear implant users.

PubMed

Srinivasan, Arthi G; Padilla, Monica; Shannon, Robert V; Landsberger, David M

2013-05-01

Cochlear implant (CI) users typically have excellent speech recognition in quiet but struggle with understanding speech in noise. It is thought that broad current spread from stimulating electrodes causes adjacent electrodes to activate overlapping populations of neurons which results in interactions across adjacent channels. Current focusing has been studied as a way to reduce spread of excitation, and therefore, reduce channel interactions. In particular, partial tripolar stimulation has been shown to reduce spread of excitation relative to monopolar stimulation. However, the crucial question is whether this benefit translates to improvements in speech perception. In this study, we compared speech perception in noise with experimental monopolar and partial tripolar speech processing strategies. The two strategies were matched in terms of number of active electrodes, microphone, filterbanks, stimulation rate and loudness (although both strategies used a lower stimulation rate than typical clinical strategies). The results of this study showed a significant improvement in speech perception in noise with partial tripolar stimulation. All subjects benefited from the current focused speech processing strategy. There was a mean improvement in speech recognition threshold of 2.7 dB in a digits in noise task and a mean improvement of 3 dB in a sentences in noise task with partial tripolar stimulation relative to monopolar stimulation. Although the experimental monopolar strategy was worse than the clinical, presumably due to different microphones, frequency allocations and stimulation rates, the experimental partial-tripolar strategy, which had the same changes, showed no acute deficit relative to the clinical. Copyright © 2013 Elsevier B.V. All rights reserved.

Visual Perception and Reading: New Clues to Patterns of Dysfunction Across Multiple Visual Channels in Developmental Dyslexia.

PubMed

Pina Rodrigues, Ana; Rebola, José; Jorge, Helena; Ribeiro, Maria José; Pereira, Marcelino; van Asselen, Marieke; Castelo-Branco, Miguel

2017-01-01

The specificity of visual channel impairment in dyslexia has been the subject of much controversy. The purpose of this study was to determine if a differential pattern of impairment can be verified between visual channels in children with developmental dyslexia, and in particular, if the pattern of deficits is more conspicuous in tasks where the magnocellular-dorsal system recruitment prevails. Additionally, we also aimed at investigating the association between visual perception thresholds and reading. In the present case-control study, we compared perception thresholds of 33 children diagnosed with developmental dyslexia and 34 controls in a speed discrimination task, an achromatic contrast sensitivity task, and a chromatic contrast sensitivity task. Moreover, we addressed the correlation between the different perception thresholds and reading performance, as assessed by means of a standardized reading test (accuracy and fluency). Group comparisons were performed by the Mann-Whitney U test, and Spearman's rho was used as a measure of correlation. Results showed that, when compared to controls, children with dyslexia were more impaired in the speed discrimination task, followed by the achromatic contrast sensitivity task, with no impairment in the chromatic contrast sensitivity task. These results are also consistent with the magnocellular theory since the impairment profile of children with dyslexia in the visual threshold tasks reflected the amount of magnocellular-dorsal stream involvement. Moreover, both speed and achromatic thresholds were significantly correlated with reading performance, in terms of accuracy and fluency. Notably, chromatic contrast sensitivity thresholds did not correlate with any of the reading measures. Our evidence stands in favor of a differential visual channel deficit in children with developmental dyslexia and contributes to the debate on the pathophysiology of reading impairments.

Age-associated variation in sensory perception of iron in drinking water and the potential for overexposure in the human population.

PubMed

Mirlohi, Susan; Dietrich, Andrea M; Duncan, Susan E

2011-08-01

Humans interact with their environment through the five senses, but little is known about population variability in the ability to assess contaminants. Sensory thresholds and biochemical indicators of metallic flavor perception in humans were evaluated for ferrous (Fe(2+)) iron in drinking water; subjects aged 19-84 years participated. Metallic flavor thresholds for individuals and subpopulations based on age were determined. Oral lipid oxidation and oral pH were measured in saliva as potential biochemical indicators. Individual thresholds were 0.007-14.14 mg/L Fe(2+) and the overall population threshold was 0.17 mg/L Fe(2+) in reagent water. Average thresholds for individuals younger and older than 50 years of age (grouped by the daily recommended nutritional guidelines for iron intake) were significantly different (p = 0.013); the population thresholds for each group were 0.045 mg/L Fe(2+) and 0.498 mg/L Fe(2+), respectively. Many subjects >50 and a few subjects <50 years were insensitive to metallic flavor. There was no correlation between age, oral lipid oxidation, and oral pH. Standardized olfactory assessment found poor sensitivity for Fe(2+) corresponded with conditions of mild, moderate, and total anosmia. The findings demonstrate an age-dependent sensitivity to iron indicating as people age they are less sensitive to metallic perception.

Retinal ganglion cell responses to voltage and current stimulation in wild-type and rd1 mouse retinas

NASA Astrophysics Data System (ADS)

Goo, Yong Sook; Ye, Jang Hee; Lee, Seokyoung; Nam, Yoonkey; Ryu, Sang Baek; Kim, Kyung Hwan

2011-06-01

Retinal prostheses are being developed to restore vision for those with retinal diseases such as retinitis pigmentosa or age-related macular degeneration. Since neural prostheses depend upon electrical stimulation to control neural activity, optimal stimulation parameters for successful encoding of visual information are one of the most important requirements to enable visual perception. In this paper, we focused on retinal ganglion cell (RGC) responses to different stimulation parameters and compared threshold charge densities in wild-type and rd1 mice. For this purpose, we used in vitro retinal preparations of wild-type and rd1 mice. When the neural network was stimulated with voltage- and current-controlled pulses, RGCs from both wild-type and rd1 mice responded; however the temporal pattern of RGC response is very different. In wild-type RGCs, a single peak within 100 ms appears, while multiple peaks (approximately four peaks) with ~10 Hz rhythm within 400 ms appear in RGCs in the degenerated retina of rd1 mice. We find that an anodic phase-first biphasic voltage-controlled pulse is more efficient for stimulation than a biphasic current-controlled pulse based on lower threshold charge density. The threshold charge densities for activation of RGCs both with voltage- and current-controlled pulses are overall more elevated for the rd1 mouse than the wild-type mouse. Here, we propose the stimulus range for wild-type and rd1 retinas when the optimal modulation of a RGC response is possible.

Within-subjects comparison of the HiRes and Fidelity120 speech processing strategies: Speech perception and its relation to place-pitch sensitivity

PubMed Central

Donaldson, Gail S.; Dawson, Patricia K.; Borden, Lamar Z.

2010-01-01

Objectives Previous studies have confirmed that current steering can increase the number of discriminable pitches available to many CI users; however, the ability to perceive additional pitches has not been linked to improved speech perception. The primary goals of this study were to determine (1) whether adult CI users can achieve higher levels of spectral-cue transmission with a speech processing strategy that implements current steering (Fidelity120) than with a predecessor strategy (HiRes) and, if so, (2) whether the magnitude of improvement can be predicted from individual differences in place-pitch sensitivity. A secondary goal was to determine whether Fidelity120 supports higher levels of speech recognition in noise than HiRes. Design A within-subjects repeated measures design evaluated speech perception performance with Fidelity120 relative to HiRes in 10 adult CI users. Subjects used the novel strategy (either HiRes or Fidelity120) for 8 weeks during the main study; a subset of five subjects used Fidelity120 for 3 additional months following the main study. Speech perception was assessed for the spectral cues related to vowel F1 frequency (Vow F1), vowel F2 frequency (Vow F2) and consonant place of articulation (Con PLC); overall transmitted information for vowels (Vow STIM) and consonants (Con STIM); and sentence recognition in noise. Place-pitch sensitivity was measured for electrode pairs in the apical, middle and basal regions of the implanted array using a psychophysical pitch-ranking task. Results With one exception, there was no effect of strategy (HiRes vs. Fidelity120) on the speech measures tested, either during the main study (n=10) or after extended use of Fidelity120 (n=5). The exception was a small but significant advantage for HiRes over Fidelity120 for the Con STIM measure during the main study. Examination of individual subjects' data revealed that 3 of 10 subjects demonstrated improved perception of one or more spectral cues with Fidelity120 relative to HiRes after 8 weeks or longer experience with Fidelity120. Another 3 subjects exhibited initial decrements in spectral cue perception with Fidelity120 at the 8 week time point; however, evidence from one subject suggested that such decrements may resolve with additional experience. Place-pitch thresholds were inversely related to improvements in Vow F2 perception with Fidelity120 relative to HiRes. However, no relationship was observed between place-pitch thresholds and the other spectral measures (Vow F1 or Con PLC). Conclusions Findings suggest that Fidelity120 supports small improvements in the perception of spectral speech cues in some Advanced Bionics CI users; however, many users show no clear benefit. Benefits are more likely to occur for vowel spectral cues (related to F1 and F2 frequency) than for consonant spectral cues (related to place of articulation). There was an inconsistent relationship between place-pitch sensitivity and improvements in spectral cue perception with Fidelity120 relative to HiRes. This may partly reflect the small number of sites at which place-pitch thresholds were measured. Contrary to some previous reports, there was no clear evidence that Fidelity120 supports improved sentence recognition in noise. PMID:21084987

The threshold signal:noise ratio in the perception of fragmented figures.

PubMed

Merkul'ev, A V; Pronin, S V; Semenov, L A; Foreman, N; Chikhman, V N; Shelepin, Yu E

2006-01-01

Perception thresholds were measured for fragmented outline figures (the Gollin test). A new approach to the question of the perception of incomplete images was developed. In this approach, figure fragmentation consisted of masking with multiplicative texture-like noise--this interference was termed "invisible" masking. The first series of studies established that the "similarity" between the amplitude-frequency spectra of test figures and "invisible" masks, expressed as a linear correlation coefficient, had significant effects on the recognition thresholds of these figures. The second series of experiments showed that progressing formation of the figures was accompanied by increases in the correlation between their spatial-frequency characteristics and the corresponding characteristics of the incomplete figure, while the correlation with the "invisible" mask decreased. It is suggested that the ratio of the correlation coefficients, characterizing the "similarity" of the fragmented figure with the intact figure and the "invisible" mask, corresponds to the signal:noise ratio. The psychophysical recognition threshold for figures for naive subjects not familiar with the test image alphabet was reached after the particular level of fragmentation at which this ratio was unity.

Lane change warning threshold based on driver perception characteristics.

PubMed

Wang, Chang; Sun, Qinyu; Fu, Rui; Li, Zhen; Zhang, Qiong

2018-08-01

Lane Change Warning system (LCW) is exploited to alleviate driver workload and improve the safety performance of lane changes. Depending on the secure threshold, the lane change warning system could transmit caution to drivers. Although the system possesses substantial benefits, it may perturb the conventional operating of the driver and affect driver judgment if the warning threshold does not conform to the driver perception of safety. Therefore, it is essential to establish an appropriate warning threshold to enhance the accuracy rate and acceptability of the lane change warning system. This research aims to identify the threshold that conforms to the driver perception of the ability to safely change lanes with a rear vehicle fast approaching. We propose a theoretical warning model of lane change based on a safe minimum distance and deceleration of the rear vehicle. For the purpose of acquiring the different safety levels of lane changes, 30 licensed drivers are recruited and we obtain the extreme moments represented by driver perception characteristics from a Front Extremity Test and a Rear Extremity Test implemented on the freeway. The required deceleration of the rear vehicle corresponding to the extreme time is calculated according to the proposed model. In light of discrepancies in the deceleration in these extremity experiments, we determine two levels of a hierarchical warning system. The purpose of the primary warning is to remind drivers of the existence of potentially dangerous vehicles and the second warning is used to warn the driver to stop changing lanes immediately. We use the signal detection theory to analyze the data. Ultimately, we confirm that the first deceleration threshold is 1.5 m/s 2 and the second deceleration threshold is 2.7 m/s 2 . The findings provide the basis for the algorithm design of LCW and enhance the acceptability of the intelligent system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Identifying cochlear implant channels with poor electrode-neuron interfaces: electrically evoked auditory brain stem responses measured with the partial tripolar configuration.

PubMed

Bierer, Julie Arenberg; Faulkner, Kathleen F; Tremblay, Kelly L

2011-01-01

The goal of this study was to compare cochlear implant behavioral measures and electrically evoked auditory brain stem responses (EABRs) obtained with a spatially focused electrode configuration. It has been shown previously that channels with high thresholds, when measured with the tripolar configuration, exhibit relatively broad psychophysical tuning curves. The elevated threshold and degraded spatial/spectral selectivity of such channels are consistent with a poor electrode-neuron interface, defined as suboptimal electrode placement or reduced nerve survival. However, the psychophysical methods required to obtain these data are time intensive and may not be practical during a clinical mapping session, especially for young children. Here, we have extended the previous investigation to determine whether a physiological approach could provide a similar assessment of channel functionality. We hypothesized that, in accordance with the perceptual measures, higher EABR thresholds would correlate with steeper EABR amplitude growth functions, reflecting a degraded electrode-neuron interface. Data were collected from six cochlear implant listeners implanted with the HiRes 90k cochlear implant (Advanced Bionics). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the partial tripolar configuration, for which a fraction of current (σ) from a center active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. EABRs were obtained in each subject for the two channels having the highest and lowest tripolar (σ = 1 or 0.9) behavioral threshold. Evoked potentials were measured with both the monopolar (σ = 0) and a more focused partial tripolar (σ ≥ 0.50) configuration. Consistent with previous studies, EABR thresholds were highly and positively correlated with behavioral thresholds obtained with both the monopolar and partial tripolar configurations. The Wave V amplitude growth functions with increasing stimulus level showed the predicted effect of shallower growth for the partial tripolar than for the monopolar configuration, but this was observed only for the low-threshold channels. In contrast, high-threshold channels showed the opposite effect; steeper growth functions were seen for the partial tripolar configuration. These results suggest that behavioral thresholds or EABRs measured with a restricted stimulus can be used to identify potentially impaired cochlear implant channels. Channels having high thresholds and steep growth functions would likely not activate the appropriate spatially restricted region of the cochlea, leading to suboptimal perception. As a clinical tool, quick identification of impaired channels could lead to patient-specific mapping strategies and result in improved speech and music perception.

Influence of intrinsic noise generated by a thermotesting device on thermal sensory detection and thermal pain detection thresholds.

PubMed

Pavlaković, G; Züchner, K; Zapf, A; Bachmann, C G; Graf, B M; Crozier, T A; Pavlaković, H

2009-08-01

Various factors can influence thermal perception threshold measurements and contribute significantly to unwanted variability of the tests. To minimize this variability, testing should be performed under strictly controlled conditions. Identifying the factors that increase the variability and eliminating their influence should increase reliability and reproducibility. Currently available thermotesting devices use a water-cooling system that generates a continuous noise of approximately 60 dB. In order to analyze whether this noise could influence the thermal threshold measurements we compared the thresholds obtained with a silent thermotesting device to those obtained with a commercially available device. The subjects were tested with one randomly chosen device on 1 day and with the other device 7 days later. At each session, heat, heat pain, cold, and cold pain thresholds were determined with three measurements. Bland-Altman analysis was used to assess agreement in measurements obtained with different devices and it was shown that the intersubject variability of the thresholds obtained with the two devices was comparable for all four thresholds tested. In contrast, the intrasubject variability of the thresholds for heat, heat pain, and cold pain detection was significantly lower with the silent device. Our results show that thermal sensory thresholds measured with the two devices are comparable. However, our data suggest that, for studies with repeated measurements on the same subjects, a silent thermotesting device may allow detection of smaller differences in the treatment effects and/or may permit the use of a smaller number of tested subjects. Muscle Nerve 40: 257-263, 2009.

Assessing the Electrode-Neuron Interface with the Electrically Evoked Compound Action Potential, Electrode Position, and Behavioral Thresholds.

PubMed

DeVries, Lindsay; Scheperle, Rachel; Bierer, Julie Arenberg

2016-06-01

Variability in speech perception scores among cochlear implant listeners may largely reflect the variable efficacy of implant electrodes to convey stimulus information to the auditory nerve. In the present study, three metrics were applied to assess the quality of the electrode-neuron interface of individual cochlear implant channels: the electrically evoked compound action potential (ECAP), the estimation of electrode position using computerized tomography (CT), and behavioral thresholds using focused stimulation. The primary motivation of this approach is to evaluate the ECAP as a site-specific measure of the electrode-neuron interface in the context of two peripheral factors that likely contribute to degraded perception: large electrode-to-modiolus distance and reduced neural density. Ten unilaterally implanted adults with Advanced Bionics HiRes90k devices participated. ECAPs were elicited with monopolar stimulation within a forward-masking paradigm to construct channel interaction functions (CIF), behavioral thresholds were obtained with quadrupolar (sQP) stimulation, and data from imaging provided estimates of electrode-to-modiolus distance and scalar location (scala tympani (ST), intermediate, or scala vestibuli (SV)) for each electrode. The width of the ECAP CIF was positively correlated with electrode-to-modiolus distance; both of these measures were also influenced by scalar position. The ECAP peak amplitude was negatively correlated with behavioral thresholds. Moreover, subjects with low behavioral thresholds and large ECAP amplitudes, averaged across electrodes, tended to have higher speech perception scores. These results suggest a potential clinical role for the ECAP in the objective assessment of individual cochlear implant channels, with the potential to improve speech perception outcomes.

Human speckle perception threshold for still images from a laser projection system.

PubMed

Roelandt, Stijn; Meuret, Youri; Jacobs, An; Willaert, Koen; Janssens, Peter; Thienpont, Hugo; Verschaffelt, Guy

2014-10-06

We study the perception of speckle by human observers in a laser projector based on a 40 persons survey. The speckle contrast is first objectively measured making use of a well-defined speckle measurement method. We statistically analyse the results of the user quality scores, revealing that the speckle perception is not only influenced by the speckle contrast settings of the projector, but it is also strongly influenced by the type of image shown. Based on the survey, we derive a speckle contrast threshold for which speckle can be seen, and separately we investigate a speckle disturbance limit that is tolerated by the majority of test persons.

Initial Assessment of the Acceptability of a Push-Pull Aedes aegypti Control Strategy in Iquitos, Peru and Kanchanaburi, Thailand

PubMed Central

Paz-Soldan, Valerie A.; Plasai, Valaikanya; Morrison, Amy C.; Rios-Lopez, Esther J.; Guedez-Gonzales, Shirly; Grieco, John P.; Mundal, Kirk; Chareonviriyaphap, Theeraphap; Achee, Nicole L.

2011-01-01

As part of a larger research program evaluating chemical threshold levels for a Push-Pull intervention to reduce man-vector (Aedes aegypti) contact, this qualitative study explored local perceptions and strategies associated with mosquito control within dengue-endemic communities in Peru and Thailand. Focus groups were used to provide preliminary information that would identify possible public acceptance issues to the Push-Pull strategy in each site. Nine focus group discussions (total of 102 individuals) conducted between September 2008 and March 2009 examined several themes: 1) current mosquito control practices; 2) perceptions of spatial repellency and contact irritancy versus killing mosquitoes; and 3) initial perceptions toward mosquito host-seeking traps. Results indicate participants use household-level strategies for insect control that reveal familiarity with the concept of spatial repellent and contact irritant actions of chemicals and that placing traps in the peridomestic environment to remove repelled mosquitoes was acceptable. Preliminary evidence suggests a Push-Pull strategy should be well accepted in these locations. These results will be beneficial for developing future large scale push-pull interventions and are currently being used to guide insecticide application strategies in (entomological) proof-of-concept studies using experimental huts. PMID:21292886

Effects of programming threshold and maplaw settings on acoustic thresholds and speech discrimination with the MED-EL COMBI 40+ cochlear implant.

PubMed

Boyd, Paul J

2006-12-01

The principal task in the programming of a cochlear implant (CI) speech processor is the setting of the electrical dynamic range (output) for each electrode, to ensure that a comfortable loudness percept is obtained for a range of input levels. This typically involves separate psychophysical measurement of electrical threshold ([theta] e) and upper tolerance levels using short current bursts generated by the fitting software. Anecdotal clinical experience and some experimental studies suggest that the measurement of [theta]e is relatively unimportant and that the setting of upper tolerance limits is more critical for processor programming. The present study aims to test this hypothesis and examines in detail how acoustic thresholds and speech recognition are affected by setting of the lower limit of the output ("Programming threshold" or "PT") to understand better the influence of this parameter and how it interacts with certain other programming parameters. Test programs (maps) were generated with PT set to artificially high and low values and tested on users of the MED-EL COMBI 40+ CI system. Acoustic thresholds and speech recognition scores (sentence tests) were measured for each of the test maps. Acoustic thresholds were also measured using maps with a range of output compression functions ("maplaws"). In addition, subjective reports were recorded regarding the presence of "background threshold stimulation" which is occasionally reported by CI users if PT is set to relatively high values when using the CIS strategy. Manipulation of PT was found to have very little effect. Setting PT to minimum produced a mean 5 dB (S.D. = 6.25) increase in acoustic thresholds, relative to thresholds with PT set normally, and had no statistically significant effect on speech recognition scores on a sentence test. On the other hand, maplaw setting was found to have a significant effect on acoustic thresholds (raised as maplaw is made more linear), which provides some theoretical explanation as to why PT has little effect when using the default maplaw of c = 500. Subjective reports of background threshold stimulation showed that most users could perceive a relatively loud auditory percept, in the absence of microphone input, when PT was set to double the behaviorally measured electrical thresholds ([theta]e), but that this produced little intrusion when microphone input was present. The results of these investigations have direct clinical relevance, showing that setting of PT is indeed relatively unimportant in terms of speech discrimination, but that it is worth ensuring that PT is not set excessively high, as this can produce distracting background stimulation. Indeed, it may even be set to minimum values without deleterious effect.

Association between the number of fungiform papillae on the tip of the tongue and sensory taste perception in children.

PubMed

Jilani, Hannah; Ahrens, Wohlfgang; Buchecker, Kirsten; Russo, Paola; Hebestreit, Antje

2017-01-01

Background : To measure sensory taste perception in children with an accurate and reproducible method is challenging and objective measurement methods are scarce. Objective : Aim was to characterize sensory taste perception, by measuring the number of fungiform papillae (FP) and to investigate whether the number of FP is associated with sensitivity for bitter taste and with taste preferences for sweet, salty, fatty or umami in children between 8 and 11 years of age. Design : Number of FP was measured with a digital camera in 83 children in a German subsample of the IDEFICS study. Among those 56 children performed a taste threshold test for bitter and taste preference tests for sweet, salty, fatty and umami. The association between the number of FP and sensory taste perception was analysed. Results : There is a tendency towards a lower number of FP in children with a higher fat preference (30 vs. 25 papillae, p=0.06). Results show no association between the number of FP and neither the bitter taste thresholds nor taste preferences for sweet, salty and umami. Conclusion : Bitter taste threshold might be independent of the number of FP, while the perception of fat was associated with the number of FP.

The Harvard Beat Assessment Test (H-BAT): a battery for assessing beat perception and production and their dissociation.

PubMed

Fujii, Shinya; Schlaug, Gottfried

2013-01-01

Humans have the abilities to perceive, produce, and synchronize with a musical beat, yet there are widespread individual differences. To investigate these abilities and to determine if a dissociation between beat perception and production exists, we developed the Harvard Beat Assessment Test (H-BAT), a new battery that assesses beat perception and production abilities. H-BAT consists of four subtests: (1) music tapping test (MTT), (2) beat saliency test (BST), (3) beat interval test (BIT), and (4) beat finding and interval test (BFIT). MTT measures the degree of tapping synchronization with the beat of music, whereas BST, BIT, and BFIT measure perception and production thresholds via psychophysical adaptive stair-case methods. We administered the H-BAT on thirty individuals and investigated the performance distribution across these individuals in each subtest. There was a wide distribution in individual abilities to tap in synchrony with the beat of music during the MTT. The degree of synchronization consistency was negatively correlated with thresholds in the BST, BIT, and BFIT: a lower degree of synchronization was associated with higher perception and production thresholds. H-BAT can be a useful tool in determining an individual's ability to perceive and produce a beat within a single session.

The Harvard Beat Assessment Test (H-BAT): a battery for assessing beat perception and production and their dissociation

PubMed Central

Fujii, Shinya; Schlaug, Gottfried

2013-01-01

Humans have the abilities to perceive, produce, and synchronize with a musical beat, yet there are widespread individual differences. To investigate these abilities and to determine if a dissociation between beat perception and production exists, we developed the Harvard Beat Assessment Test (H-BAT), a new battery that assesses beat perception and production abilities. H-BAT consists of four subtests: (1) music tapping test (MTT), (2) beat saliency test (BST), (3) beat interval test (BIT), and (4) beat finding and interval test (BFIT). MTT measures the degree of tapping synchronization with the beat of music, whereas BST, BIT, and BFIT measure perception and production thresholds via psychophysical adaptive stair-case methods. We administered the H-BAT on thirty individuals and investigated the performance distribution across these individuals in each subtest. There was a wide distribution in individual abilities to tap in synchrony with the beat of music during the MTT. The degree of synchronization consistency was negatively correlated with thresholds in the BST, BIT, and BFIT: a lower degree of synchronization was associated with higher perception and production thresholds. H-BAT can be a useful tool in determining an individual's ability to perceive and produce a beat within a single session. PMID:24324421

Thermal sensation and climate: a comparison of UTCI and PET thresholds in different climates.

PubMed

Pantavou, Katerina; Lykoudis, Spyridon; Nikolopoulou, Marialena; Tsiros, Ioannis X

2018-06-07

The influence of physiological acclimatization and psychological adaptation on thermal perception is well documented and has revealed the importance of thermal experience and expectation in the evaluation of environmental stimuli. Seasonal patterns of thermal perception have been studied, and calibrated thermal indices' scales have been proposed to obtain meaningful interpretations of thermal sensation indices in different climate regions. The current work attempts to quantify the contribution of climate to the long-term thermal adaptation by examining the relationship between climate normal annual air temperature (1971-2000) and such climate-calibrated thermal indices' assessment scales. The thermal sensation ranges of two thermal indices, the Universal Thermal Climate Index (UTCI) and the Physiological Equivalent Temperature Index (PET), were calibrated for three warm temperate climate contexts (Cfa, Cfb, Csa), against the subjective evaluation of the thermal environment indicated by interviewees during field surveys conducted at seven European cities: Athens (GR), Thessaloniki (GR), Milan (IT), Fribourg (CH), Kassel (DE), Cambridge (UK), and Sheffield (UK), under the same research protocol. Then, calibrated scales for other climate contexts were added from the literature, and the relationship between the respective scales' thresholds and climate normal annual air temperature was examined. To maintain the maximum possible comparability, three methods were applied for the calibration, namely linear, ordinal, and probit regression. The results indicated that the calibrated UTCI and PET thresholds increase with the climate normal annual air temperature of the survey city. To investigate further climates, we also included in the analysis results of previous studies presenting only thresholds for neutral thermal sensation. The average increase of the respective thresholds in the case of neutral thermal sensation was about 0.6 °C for each 1 °C increase of the normal annual air temperature for both indices, statistically significant only for PET though.

Exhibition of Stochastic Resonance in Vestibular Perception

NASA Technical Reports Server (NTRS)

Galvan-Garza, R. C.; Clark, T. K.; Merfeld, D. M.; Bloomberg, J. J.; Oman, C. M.; Mulavara, A. P.

2016-01-01

Astronauts experience sensorimotor changes during spaceflight, particularly during G-transitions. Post flight sensorimotor changes include spatial disorientation, along with postural and gait instability that may degrade operational capabilities of the astronauts and endanger the crew. A sensorimotor countermeasure that mitigates these effects would improve crewmember safety and decrease risk. The goal of this research is to investigate the potential use of stochastic vestibular stimulation (SVS) as a technology to improve sensorimotor function. We hypothesize that low levels of SVS will improve sensorimotor perception through the phenomenon of stochastic resonance (SR), when the response of a nonlinear system to a weak input signal is enhanced by the application of a particular nonzero level of noise. This study aims to advance the development of SVS as a potential countermeasure by 1) demonstrating the exhibition of stochastic resonance in vestibular perception, a vital component of sensorimotor function, 2) investigating the repeatability of SR exhibition, and 3) determining the relative contribution of the semicircular canals (SCC) and otolith (OTO) organs to vestibular perceptual SR. A constant current stimulator was used to deliver bilateral bipolar SVS via electrodes placed on each of the mastoid processes, as previously done. Vestibular perceptual motion recognition thresholds were measured using a 6-degree of freedom MOOG platform and a 150 trial 3-down/1-up staircase procedure. In the first test session, we measured vestibular perceptual thresholds in upright roll-tilt at 0.2 Hz (SCC+OTO) with SVS ranging from 0-700 µA. In a second test session a week later, we re-measured roll-tilt thresholds with 0, optimal (from test session 1), and 1500 µA SVS levels. A subset of these subjects, plus naive subjects, participated in two additional test sessions in which we measured thresholds in supine roll-rotation at 0.2 Hz (SCC) and upright y-translation at 1 Hz (OTO) with SVS up to 700 µA. A sinusoidal galvanic vestibular stimulation (GVS) perceptual threshold was also measured on each test day and used to normalize the SVS levels across subjects. In roll-tilt thresholds with SVS, the characteristic SR curve was qualitatively exhibited in 10 of 12 subjects, and the improvement in motion threshold was significant in 6 subjects, indicating that optimal SVS improved passive body motion perception in a way that is consistent with classical SR theory. A probabilistic comparison to numeric simulations further validated these experimental results. On the second test session, 4 out of the 10 SR exhibitors showed repeated improvement with SVS compared to the no SVS condition. Data collection is ongoing for the last two test sessions in which SCC and OTO only perceptual motion recognition thresholds are being measured with SVS. The final results of these test sessions will give insight into whether vestibular perceptual SR can occur when only one type of vestibular sensor is sensing motion or if it is more evident when sensory integration between the SCC and OTO is occurring during the motion. The overall purpose of this research is to further quantify the effects of SVS on various sensorimotor tasks and to gain a more fundamental understanding of how SVS causes SR in the vestibular system. In the context of human space flight, results from this research will help in understanding how SVS may be practically implemented in the future as a component of a comprehensive countermeasure plan for G-transition adaptation.

Teaching Evolution: The Blog as a Liminal Space

ERIC Educational Resources Information Center

Akkaraju, Shylaja; Wolf, Alexander

2016-01-01

A "threshold concept" is a challenging concept that acts as a doorway leading to deeper understanding and a dramatic shift in perception. A learner that is involved in grasping a threshold concept is said to be undergoing a threshold experience within a "liminal space" or learning environment. We used the blog as a liminal…

Cross-modal cueing effects of visuospatial attention on conscious somatosensory perception.

PubMed

Doruk, Deniz; Chanes, Lorena; Malavera, Alejandra; Merabet, Lotfi B; Valero-Cabré, Antoni; Fregni, Felipe

2018-04-01

The impact of visuospatial attention on perception with supraliminal stimuli and stimuli at the threshold of conscious perception has been previously investigated. In this study, we assess the cross-modal effects of visuospatial attention on conscious perception for near-threshold somatosensory stimuli applied to the face. Fifteen healthy participants completed two sessions of a near-threshold cross-modality cue-target discrimination/conscious detection paradigm. Each trial began with an endogenous visuospatial cue that predicted the location of a weak near-threshold electrical pulse delivered to the right or left cheek with high probability (∼75%). Participants then completed two tasks: first, a forced-choice somatosensory discrimination task (felt once or twice?) and then, a somatosensory conscious detection task (did you feel the stimulus and, if yes, where (left/right)?). Somatosensory discrimination was evaluated with the response reaction times of correctly detected targets, whereas the somatosensory conscious detection was quantified using perceptual sensitivity (d') and response bias (beta). A 2 × 2 repeated measures ANOVA was used for statistical analysis. In the somatosensory discrimination task (1 st task), participants were significantly faster in responding to correctly detected targets (p < 0.001). In the somatosensory conscious detection task (2 nd task), a significant effect of visuospatial attention on response bias (p = 0.008) was observed, suggesting that participants had a less strict criterion for stimuli preceded by spatially valid than invalid visuospatial cues. We showed that spatial attention has the potential to modulate the discrimination and the conscious detection of near-threshold somatosensory stimuli as measured, respectively, by a reduction of reaction times and a shift in response bias toward less conservative responses when the cue predicted stimulus location. A shift in response bias indicates possible effects of spatial attention on internal decision processes. The lack of significant results in perceptual sensitivity (d') could be due to weaker effects of endogenous attention on perception.

The Measurement of the Sensory Recovery Period in Zygoma and Blow-Out Fractures with Neurometer Current Perception Threshold.

PubMed

Oh, Daemyung; Yun, Taebin; Kim, Junhyung; Choi, Jaehoon; Jeong, Woonhyeok; Chu, Hojun; Lee, Soyoung

2016-09-01

Facial hypoesthesia is one of the most troublesome complaints in the management of facial bone fractures. However, there is a lack of literature on facial sensory recovery after facial trauma. The purpose of this study was to evaluate the facial sensory recovery period for facial bone fractures using Neurometer. Sixty-three patients who underwent open reduction of zygomatic and blowout fractures between December 2013 and July 2015 were included in the study. The facial sensory status of the patients was repeatedly examined preoperatively and postoperatively by Neurometer current perception threshold (CPT) until the results were normalized. Among the 63 subjects, 30 patients had normal Neurometer results preoperatively and postoperatively. According to fracture types, 17 patients with blowout fracture had a median recovery period of 0.25 months. Twelve patients with zygomatic fracture had a median recovery period of 1.00 month. Four patients with both fracture types had a median recovery period of 0.625 months. The median recovery period of all 33 patients was 0.25 months. There was no statistically significant difference in the sensory recovery period between types and subgroups of zygomatic and blowout fractures. In addition, there was no statistically significant difference in the sensory recovery period according to Neurometer results and the patients' own subjective reports. Neurometer CPT is effective for evaluating and comparing preoperative and postoperative facial sensory status and evaluating the sensory recovery period in facial bone fracture patients.

Decomposing fear perception: A combination of psychophysics and neurometric modeling of fear perception

PubMed Central

Forscher, Emily C.; Zheng, Yan; Ke, Zijun; Folstein, Jonathan; Li, Wen

2016-01-01

Emotion perception is known to involve multiple operations and waves of analysis, but specific nature of these processes remains poorly understood. Combining psychophysical testing and neurometric analysis of event-related potentials (ERPs) in a fear detection task with parametrically-varied fear intensities (N=45), we sought to elucidate key processes in fear perception. Building on psychophysics marking fear perception thresholds, our neurometric model fitting identified several putative operations and stages: four key processes arose in sequence following face presentation—fear-neutral categorization (P1 at 100 ms), fear detection (P300 at 320 ms), valuation (early subcomponent of the late positive potential/LPP at 400–500 ms) and conscious awareness (late subcomponent LPP at 500–600 ms). Furthermore, within-subject brain-behavior association suggests that initial emotion categorization was mandatory and detached from behavior whereas valuation and conscious awareness directly impacted behavioral outcome (explaining 17% and 31% of the total variance, respectively). The current study thus reveals the chronometry of fear perception, ascribing psychological meaning to distinct underlying processes. The combination of early categorization and late valuation of fear reconciles conflicting (categorical versus dimensional) emotion accounts, lending support to a hybrid model. Importantly, future research could specifically interrogate these psychological processes in various behaviors and psychopathologies (e.g., anxiety and depression). PMID:27546075

Effects of electrode size and spacing on sensory modalities in the phantom thumb perception area for the forearm amputees.

PubMed

Li, P; Chai, G H; Zhu, K H; Lan, N; Sui, X H

2015-01-01

Tactile sensory feedback plays a key role in accomplishing the dexterous manipulation of prosthetic hands for the amputees, and the non-invasive transcutaneous electrical nerve stimulation (TENS) of the phantom finger perception (PFP) area would be an effective way to realize sensory feedback clinically. In order to realize the high-spatial-resolution tactile sensory feedback in the PFP region, we investigated the effects of electrode size and spacing on the tactile sensations for potentially optimizing the surface electrode array configuration. Six forearm-amputated subjects were recruited in the psychophysical studies. With the diameter of the circular electrode increasing from 3 mm to 12 mm, the threshold current intensity was enhanced correspondingly under different sensory modalities. The smaller electrode could potentially lead to high sensation spatial resolution. Whereas, the smaller the electrode, the less the number of sensory modalities. For an Φ-3 mm electrode, it is even hard for the subject to perceive any perception modalities under normal stimulating current. In addition, the two-electrode discrimination distance (TEDD) in the phantom thumb perception area decreased with electrode size decreasing in two directions of parallel or perpendicular to the forearm. No significant difference of TEDD existed along the two directions. Studies in this paper would guide the configuration optimization of the TENS electrode array for potential high spatial-resolution sensory feedback.

Gain and phase of perceived virtual rotation evoked by electrical vestibular stimuli

PubMed Central

Peters, Ryan M.; Rasman, Brandon G.; Inglis, J. Timothy

2015-01-01

Galvanic vestibular stimulation (GVS) evokes a perception of rotation; however, very few quantitative data exist on the matter. We performed psychophysical experiments on virtual rotations experienced when binaural bipolar electrical stimulation is applied over the mastoids. We also performed analogous real whole body yaw rotation experiments, allowing us to compare the frequency response of vestibular perception with (real) and without (virtual) natural mechanical stimulation of the semicircular canals. To estimate the gain of vestibular perception, we measured direction discrimination thresholds for virtual and real rotations. Real direction discrimination thresholds decreased at higher frequencies, confirming multiple previous studies. Conversely, virtual direction discrimination thresholds increased at higher frequencies, implying low-pass filtering of the virtual perception process occurring potentially anywhere between afferent transduction and cortical responses. To estimate the phase of vestibular perception, participants manually tracked their perceived position during sinusoidal virtual and real kinetic stimulation. For real rotations, perceived velocity was approximately in phase with actual velocity across all frequencies. Perceived virtual velocity was in phase with the GVS waveform at low frequencies (0.05 and 0.1 Hz). As frequency was increased to 1 Hz, the phase of perceived velocity advanced relative to the GVS waveform. Therefore, at low frequencies GVS is interpreted as an angular velocity signal and at higher frequencies GVS becomes interpreted increasingly as an angular position signal. These estimated gain and phase spectra for vestibular perception are a first step toward generating well-controlled virtual vestibular percepts, an endeavor that may reveal the usefulness of GVS in the areas of clinical assessment, neuroprosthetics, and virtual reality. PMID:25925318

Gain and phase of perceived virtual rotation evoked by electrical vestibular stimuli.

PubMed

Peters, Ryan M; Rasman, Brandon G; Inglis, J Timothy; Blouin, Jean-Sébastien

2015-07-01

Galvanic vestibular stimulation (GVS) evokes a perception of rotation; however, very few quantitative data exist on the matter. We performed psychophysical experiments on virtual rotations experienced when binaural bipolar electrical stimulation is applied over the mastoids. We also performed analogous real whole body yaw rotation experiments, allowing us to compare the frequency response of vestibular perception with (real) and without (virtual) natural mechanical stimulation of the semicircular canals. To estimate the gain of vestibular perception, we measured direction discrimination thresholds for virtual and real rotations. Real direction discrimination thresholds decreased at higher frequencies, confirming multiple previous studies. Conversely, virtual direction discrimination thresholds increased at higher frequencies, implying low-pass filtering of the virtual perception process occurring potentially anywhere between afferent transduction and cortical responses. To estimate the phase of vestibular perception, participants manually tracked their perceived position during sinusoidal virtual and real kinetic stimulation. For real rotations, perceived velocity was approximately in phase with actual velocity across all frequencies. Perceived virtual velocity was in phase with the GVS waveform at low frequencies (0.05 and 0.1 Hz). As frequency was increased to 1 Hz, the phase of perceived velocity advanced relative to the GVS waveform. Therefore, at low frequencies GVS is interpreted as an angular velocity signal and at higher frequencies GVS becomes interpreted increasingly as an angular position signal. These estimated gain and phase spectra for vestibular perception are a first step toward generating well-controlled virtual vestibular percepts, an endeavor that may reveal the usefulness of GVS in the areas of clinical assessment, neuroprosthetics, and virtual reality. Copyright © 2015 the American Physiological Society.

[Correlation of perceptive temperature threshold of oral mucosa and sympathetic skin response].

PubMed

Wang, Z G; Dong, T Z; Li, J; Chen, G

2018-02-09

Objectives: To explore the critical values of temperature perception in various mucosa sites of oral cavity and to draw the perceptive temperature threshold maps in healthy volunteers. To observe the interrelationship between subjective cognitive perception and sympathetic skin response (SSR) under various levels of thermal stimuli. Methods: Forty-two healthy volunteers (recruited from the students of Tianjin Medical University, 16 females and 26 males) were enrolled in the present study. The whole oral mucosa of each subject was divided into multiple partitions according to the mucosa type as well as tooth position. Peltier patch (commodity name) semiconductor chip was placed in the central part of each subarea of the mucosa. The stimulus was increased or decreased at 1 ℃ each time from a baseline temperature of 37 ℃. Warm (WT) and cold (CT) perception thresholds were measured thereafter respectively. A topographic temperature map of the oral mucosa for each subject was drew. Furthermore, the SSR was elicited and recorded at three temperature levels of 50 ℃, 55 ℃, 60 ℃ respectively. Analog test with visual analogue scale (VAS) and McGill scales were also performed. Data were statistically analyzed with variance and generalized estimation equation. Results: The tip of the tongue was the most sensitive area with both WT [(38.8±2.1) ℃, P< 0.05] and CT [(23.5±4.2) ℃, P< 0.05]. The highest heat threshold of gingival mucosa was in the left lower posterior teeth area [(49.9±3.7) ℃, P< 0.05], and the highest cold threshold of gingival mucosa was in the left upper posterior teeth area [(15.9±5.5) ℃, P< 0.05]. The perceptive temperature threshold increased gradually from the midline to both left and right sides were observed symmetrically and bilaterally. There was no statistically significant differences in temperature perception threshold between males and females [WT, male (44.8±3.1) ℃, female (44.8±3.2) ℃, OR= 1.100, P= 0.930; CT, Male (18.4±4.9) ℃, female (20.8±4.8) ℃, OR= 0.157, P= 0.210]. The SSR amplitude at sites of the tongue tip and the lower lip were increased with the rise of temperature [tongue tip (4.58±4.04) mv, P< 0.05, lower lip (2.89±3.01) mv, P< 0.05]. However, SSR amplitude values had no significant differences between males and females [tongue tip, male (2.00±2.16) mv, female (1.89±1.20) mv, P= 0.890; lower lip, male (0.94±0.82) mv, female (0.85±0.68) mv, P= 0.887]. Nevertheless, the amplitude of SSR and the VAS score of subjects showed a similar trend. Conclusions: The temperature perception levels were different amongst sites of lip, buccal mucosa, tongue dorsal mucosa and gingival mucosa. SSR amplitude values could reflect the responses of the mouth to the thermal stimuli.

Perceiving nasal patency through mucosal cooling rather than air temperature or nasal resistance.

PubMed

Zhao, Kai; Blacker, Kara; Luo, Yuehao; Bryant, Bruce; Jiang, Jianbo

2011-01-01

Adequate perception of nasal airflow (i.e., nasal patency) is an important consideration for patients with nasal sinus diseases. The perception of a lack of nasal patency becomes the primary symptom that drives these patients to seek medical treatment. However, clinical assessment of nasal patency remains a challenge because we lack objective measurements that correlate well with what patients perceive. The current study examined factors that may influence perceived patency, including air temperature, humidity, mucosal cooling, nasal resistance, and trigeminal sensitivity. Forty-four healthy subjects rated nasal patency while sampling air from three facial exposure boxes that were ventilated with untreated room air, cold air, and dry air, respectively. In all conditions, air temperature and relative humidity inside each box were recorded with sensors connected to a computer. Nasal resistance and minimum airway cross-sectional area (MCA) were measured using rhinomanometry and acoustic rhinometry, respectively. General trigeminal sensitivity was assessed through lateralization thresholds to butanol. No significant correlation was found between perceived patency and nasal resistance or MCA. In contrast, air temperature, humidity, and butanol threshold combined significantly contributed to the ratings of patency, with mucosal cooling (heat loss) being the most heavily weighted predictor. Air humidity significantly influences perceived patency, suggesting that mucosal cooling rather than air temperature alone provides the trigeminal sensation that results in perception of patency. The dynamic cooling between the airstream and the mucosal wall may be quantified experimentally or computationally and could potentially lead to a new clinical evaluation tool.

Perceiving Nasal Patency through Mucosal Cooling Rather than Air Temperature or Nasal Resistance

PubMed Central

Zhao, Kai; Blacker, Kara; Luo, Yuehao; Bryant, Bruce; Jiang, Jianbo

2011-01-01

Adequate perception of nasal airflow (i.e., nasal patency) is an important consideration for patients with nasal sinus diseases. The perception of a lack of nasal patency becomes the primary symptom that drives these patients to seek medical treatment. However, clinical assessment of nasal patency remains a challenge because we lack objective measurements that correlate well with what patients perceive.The current study examined factors that may influence perceived patency, including air temperature, humidity, mucosal cooling, nasal resistance, and trigeminal sensitivity. Forty-four healthy subjects rated nasal patency while sampling air from three facial exposure boxes that were ventilated with untreated room air, cold air, and dry air, respectively. In all conditions, air temperature and relative humidity inside each box were recorded with sensors connected to a computer. Nasal resistance and minimum airway cross-sectional area (MCA) were measured using rhinomanometry and acoustic rhinometry, respectively. General trigeminal sensitivity was assessed through lateralization thresholds to butanol. No significant correlation was found between perceived patency and nasal resistance or MCA. In contrast, air temperature, humidity, and butanol threshold combined significantly contributed to the ratings of patency, with mucosal cooling (heat loss) being the most heavily weighted predictor. Air humidity significantly influences perceived patency, suggesting that mucosal cooling rather than air temperature alone provides the trigeminal sensation that results in perception of patency. The dynamic cooling between the airstream and the mucosal wall may be quantified experimentally or computationally and could potentially lead to a new clinical evaluation tool. PMID:22022361

Auditory Speech Perception Tests in Relation to the Coding Strategy in Cochlear Implant.

PubMed

Bazon, Aline Cristine; Mantello, Erika Barioni; Gonçales, Alina Sanches; Isaac, Myriam de Lima; Hyppolito, Miguel Angelo; Reis, Ana Cláudia Mirândola Barbosa

2016-07-01

The objective of the evaluation of auditory perception of cochlear implant users is to determine how the acoustic signal is processed, leading to the recognition and understanding of sound. To investigate the differences in the process of auditory speech perception in individuals with postlingual hearing loss wearing a cochlear implant, using two different speech coding strategies, and to analyze speech perception and handicap perception in relation to the strategy used. This study is prospective cross-sectional cohort study of a descriptive character. We selected ten cochlear implant users that were characterized by hearing threshold by the application of speech perception tests and of the Hearing Handicap Inventory for Adults. There was no significant difference when comparing the variables subject age, age at acquisition of hearing loss, etiology, time of hearing deprivation, time of cochlear implant use and mean hearing threshold with the cochlear implant with the shift in speech coding strategy. There was no relationship between lack of handicap perception and improvement in speech perception in both speech coding strategies used. There was no significant difference between the strategies evaluated and no relation was observed between them and the variables studied.

Exhibition of stochastic resonance in vestibular tilt motion perception.

PubMed

Galvan-Garza, R C; Clark, T K; Mulavara, A P; Oman, C M

2018-04-03

Stochastic Resonance (SR) is a phenomenon broadly described as "noise benefit". The application of subsensory electrical Stochastic Vestibular Stimulation (SVS) via electrodes behind each ear has been used to improve human balance and gait, but its effect on motion perception thresholds has not been examined. This study investigated the capability of subsensory SVS to reduce vestibular motion perception thresholds in a manner consistent with a characteristic bell-shaped SR curve. We measured upright, head-centered, roll tilt Direction Recognition (DR) thresholds in the dark in 12 human subjects with the application of wideband 0-30 Hz SVS ranging from ±0-700 μA. To conservatively assess if SR was exhibited, we compared the proportions of both subjective and statistical SR exhibition in our experimental data to proportions of SR exhibition in multiple simulation cases with varying underlying SR behavior. Analysis included individual and group statistics. As there is not an established mathematical definition, three humans subjectively judged that SR was exhibited in 78% of subjects. "Statistically significant SR exhibition", which additionally required that a subject's DR threshold with SVS be significantly lower than baseline (no SVS), was present in 50% of subjects. Both percentages were higher than simulations suggested could occur simply by chance. For SR exhibitors, defined by subjective or statistically significant criteria, the mean DR threshold improved by -30% and -39%, respectively. The largest individual improvement was -47%. At least half of the subjects were better able to perceive passive body motion with the application of subsensory SVS. This study presents the first conclusive demonstration of SR in vestibular motion perception. Copyright © 2018 Elsevier Inc. All rights reserved.

Audio-visual temporal perception in children with restored hearing.

PubMed

Gori, Monica; Chilosi, Anna; Forli, Francesca; Burr, David

2017-05-01

It is not clear how audio-visual temporal perception develops in children with restored hearing. In this study we measured temporal discrimination thresholds with an audio-visual temporal bisection task in 9 deaf children with restored audition, and 22 typically hearing children. In typically hearing children, audition was more precise than vision, with no gain in multisensory conditions (as previously reported in Gori et al. (2012b)). However, deaf children with restored audition showed similar thresholds for audio and visual thresholds and some evidence of gain in audio-visual temporal multisensory conditions. Interestingly, we found a strong correlation between auditory weighting of multisensory signals and quality of language: patients who gave more weight to audition had better language skills. Similarly, auditory thresholds for the temporal bisection task were also a good predictor of language skills. This result supports the idea that the temporal auditory processing is associated with language development. Copyright © 2017. Published by Elsevier Ltd.

"The World is No Longer Flat to Me": Student Perceptions of Threshold Concepts in World Regional Geography

ERIC Educational Resources Information Center

Fouberg, Erin H.

2013-01-01

Through qualitative analysis of 80 student essays, the author examines geographic concepts students describe as holding traits of threshold concepts. With a group of 11 Honors students, the author employs metacogntion, asking students to analyze their own learning to discover their threshold concepts. Recognizing the role of liminality, this study…

Gap detection measured with electrically evoked auditory event-related potentials and speech-perception abilities in children with auditory neuropathy spectrum disorder.

PubMed

He, Shuman; Grose, John H; Teagle, Holly F B; Woodard, Jennifer; Park, Lisa R; Hatch, Debora R; Buchman, Craig A

2013-01-01

This study aimed (1) to investigate the feasibility of recording the electrically evoked auditory event-related potential (eERP), including the onset P1-N1-P2 complex and the electrically evoked auditory change complex (EACC) in response to temporal gaps, in children with auditory neuropathy spectrum disorder (ANSD); and (2) to evaluate the relationship between these measures and speech-perception abilities in these subjects. Fifteen ANSD children who are Cochlear Nucleus device users participated in this study. For each subject, the speech-processor microphone was bypassed and the eERPs were elicited by direct stimulation of one mid-array electrode (electrode 12). The stimulus was a train of biphasic current pulses 800 msec in duration. Two basic stimulation conditions were used to elicit the eERP. In the no-gap condition, the entire pulse train was delivered uninterrupted to electrode 12, and the onset P1-N1-P2 complex was measured relative to the stimulus onset. In the gapped condition, the stimulus consisted of two pulse train bursts, each being 400 msec in duration, presented sequentially on the same electrode and separated by one of five gaps (i.e., 5, 10, 20, 50, and 100 msec). Open-set speech-perception ability of these subjects with ANSD was assessed using the phonetically balanced kindergarten (PBK) word lists presented at 60 dB SPL, using monitored live voice in a sound booth. The eERPs were recorded from all subjects with ANSD who participated in this study. There were no significant differences in test-retest reliability, root mean square amplitude or P1 latency for the onset P1-N1-P2 complex between subjects with good (>70% correct on PBK words) and poorer speech-perception performance. In general, the EACC showed less mature morphological characteristics than the onset P1-N1-P2 response recorded from the same subject. There was a robust correlation between the PBK word scores and the EACC thresholds for gap detection. Subjects with poorer speech-perception performance showed larger EACC thresholds in this study. These results demonstrate the feasibility of recording eERPs from implanted children with ANSD, using direct electrical stimulation. Temporal-processing deficits, as demonstrated by large EACC thresholds for gap detection, might account in part for the poor speech-perception performances observed in a subgroup of implanted subjects with ANSD. This finding suggests that the EACC elicited by changes in temporal continuity (i.e., gap) holds promise as a predictor of speech-perception ability among implanted children with ANSD.

Identifying cochlear implant channels with poor electrode-neuron interface: electrically-evoked auditory brainstem responses measured with the partial tripolar configuration

PubMed Central

Bierer, Julie Arenberg; Faulkner, Kathleen F.; Tremblay, Kelly L.

2011-01-01

Objectives The goal of this study was to compare cochlear implant behavioral measures and electrically-evoked auditory brainstem responses (EABRs) obtained with a spatially focused electrode configuration. It has been shown previously that channels with high thresholds, when measured with the tripolar configuration, exhibit relatively broad psychophysical tuning curves (Bierer and Faulkner, 2010). The elevated threshold and degraded spatial/spectral selectivity of such channels are consistent with a poor electrode-neuron interface, such as suboptimal electrode placement or reduced nerve survival. However, the psychophysical methods required to obtain these data are time intensive and may not be practical during a clinical mapping procedure, especially for young children. Here we have extended the previous investigation to determine if a physiological approach could provide a similar assessment of channel functionality. We hypothesized that, in accordance with the perceptual measures, higher EABR thresholds would correlate with steeper EABR amplitude growth functions, reflecting a degraded electrode-neuron interface. Design Data were collected from six cochlear implant listeners implanted with the HiRes 90k cochlear implant (Advanced Bionics). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the partial tripolar configuration, for which a fraction of current (σ) from a center active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. EABRs were obtained in each subject for the two channels having the highest and lowest tripolar (σ=1 or 0.9) behavioral threshold. Evoked potentials were measured with both the monopolar (σ=0) and a more focused partial tripolar (σ ≥ 0.50) configuration. Results Consistent with previous studies, EABR thresholds were highly and positively correlated with behavioral thresholds obtained with both the monopolar and partial tripolar configurations. The Wave V amplitude growth functions with increasing stimulus level showed the predicted effect of shallower growth for the partial tripolar than for the monopolar configuration, but this was observed only for the low threshold channel. In contrast, high-threshold channels showed the opposite effect; steeper growth functions were seen for the partial tripolar configuration. Conclusions These results suggest that behavioral thresholds or EABRs measured with a restricted stimulus can be used to identify potentially impaired cochlear implant channels. Channels having high thresholds and steep growth functions would likely not activate the appropriate spatially restricted region of the cochlea, leading to suboptimal perception. As a clinical tool, quick identification of impaired channels could lead to patient-specific mapping strategies and result in improved speech and music perception. PMID:21178633

The effect of phasic auditory alerting on visual perception.

PubMed

Petersen, Anders; Petersen, Annemarie Hilkjær; Bundesen, Claus; Vangkilde, Signe; Habekost, Thomas

2017-08-01

Phasic alertness refers to a short-lived change in the preparatory state of the cognitive system following an alerting signal. In the present study, we examined the effect of phasic auditory alerting on distinct perceptual processes, unconfounded by motor components. We combined an alerting/no-alerting design with a pure accuracy-based single-letter recognition task. Computational modeling based on Bundesen's Theory of Visual Attention was used to examine the effect of phasic alertness on visual processing speed and threshold of conscious perception. Results show that phasic auditory alertness affects visual perception by increasing the visual processing speed and lowering the threshold of conscious perception (Experiment 1). By manipulating the intensity of the alerting cue, we further observed a positive relationship between alerting intensity and processing speed, which was not seen for the threshold of conscious perception (Experiment 2). This was replicated in a third experiment, in which pupil size was measured as a physiological marker of alertness. Results revealed that the increase in processing speed was accompanied by an increase in pupil size, substantiating the link between alertness and processing speed (Experiment 3). The implications of these results are discussed in relation to a newly developed mathematical model of the relationship between levels of alertness and the speed with which humans process visual information. Copyright © 2017 Elsevier B.V. All rights reserved.

A comparison of signal detection theory to the objective threshold/strategic model of unconscious perception.

PubMed

Haase, Steven J; Fisk, Gary D

2011-08-01

A key problem in unconscious perception research is ruling out the possibility that weak conscious awareness of stimuli might explain the results. In the present study, signal detection theory was compared with the objective threshold/strategic model as explanations of results for detection and identification sensitivity in a commonly used unconscious perception task. In the task, 64 undergraduate participants detected and identified one of four briefly displayed, visually masked letters. Identification was significantly above baseline (i.e., proportion correct > .25) at the highest detection confidence rating. This result is most consistent with signal detection theory's continuum of sensory states and serves as a possible index of conscious perception. However, there was limited support for the other model in the form of a predicted "looker's inhibition" effect, which produced identification performance that was significantly below baseline. One additional result, an interaction between the target stimulus and type of mask, raised concerns for the generality of unconscious perception effects.

Southeast PAVE PAWS Radar System. Environmental Assessment.

DTIC Science & Technology

1983-03-01

reported, including fatigue, irritability, sleepiness, partial loss of memory, lower heart- beat rates, hypertension, hypotension, cardiac pain, and...Because such audiograms do not test hearing above 8 klz, binaural hearing thresholds were also determined for seven of the subjects for frequencies...perception and hearing ability above 8 kl:z as determined from the binaural thresholds. The average threshold pulse power density for 15-microsecond

Tactile learning and the individual evaluation of the reward in honey bees (Apis mellifera L.).

PubMed

Scheiner, R; Erber, J; Page, R E

1999-07-01

Using the proboscis extension response we conditioned pollen and nectar foragers of the honey bee (Apis mellifera L.) to tactile patterns under laboratory conditions. Pollen foragers demonstrated better acquisition, extinction, and reversal learning than nectar foragers. We tested whether the known differences in response thresholds to sucrose between pollen and nectar foragers could explain the observed differences in learning and found that nectar foragers with low response thresholds performed better during acquisition and extinction than ones with higher thresholds. Conditioning pollen and nectar foragers with similar response thresholds did not yield differences in their learning performance. These results suggest that differences in the learning performance of pollen and nectar foragers are a consequence of differences in their perception of sucrose. Furthermore, we analysed the effect which the perception of sucrose reward has on associative learning. Nectar foragers with uniform low response thresholds were conditioned using varying concentrations of sucrose. We found significant positive correlations between the concentrations of the sucrose rewards and the performance during acquisition and extinction. The results are summarised in a model which describes the relationships between learning performance, response threshold to sucrose, concentration of sucrose and the number of rewards.

Test-retest reliability of neurophysiological tests of hand-arm vibration syndrome in vibration exposed workers and unexposed referents.

PubMed

Gerhardsson, Lars; Gillström, Lennart; Hagberg, Mats

2014-01-01

Exposure to hand-held vibrating tools may cause the hand-arm vibration syndrome (HAVS). The aim was to study the test-retest reliability of hand and muscle strength tests, and tests for the determination of thermal and vibration perception thresholds, which are used when investigating signs of neuropathy in vibration exposed workers. In this study, 47 vibration exposed workers who had been investigated at the department of Occupational and Environmental Medicine in Gothenburg were compared with a randomized sample of 18 unexposed subjects from the general population of the city of Gothenburg. All participants passed a structured interview, answered several questionnaires and had a physical examination including hand and finger muscle strength tests, determination of vibrotactile (VPT) and thermal perception thresholds (TPT). Two weeks later, 23 workers and referents, selected in a randomized manner, were called back for the same test-procedures for the evaluation of test-retest reliability. The test-retest reliability after a two week interval expressed as limits of agreement (LOA; Bland-Altman), intra-class correlation coefficients (ICC) and Pearson correlation coefficients was excellent for tests with the Baseline hand grip, Pinch-grip and 3-Chuck grip among the exposed workers and referents (N = 23: percentage of differences within LOA 91 - 100%; ICC-values ≥0.93; Pearson r ≥0.93). The test-retest reliability was also excellent (percentage of differences within LOA 96-100 %) for the determination of vibration perception thresholds in digits 2 and 5 bilaterally as well as for temperature perception thresholds in digits 2 and 5, bilaterally (percentage of differences within LOA 91 - 96%). For ICC and Pearson r the results for vibration perception thresholds were good for digit 2, left hand and for digit 5, bilaterally (ICC ≥ 0.84; r ≥0.85), and lower (ICC = 0.59; r = 0.59) for digit 2, right hand. For the latter two indices the test-retest reliability for the determination of temperature thresholds was lower and showed more varying results. The strong test-retest reliability for hand and muscle strength tests as well as for the determination of VPTs makes these procedures useful for diagnostic purposes and follow-up studies in vibration exposed workers.

Cortical response tracking the conscious experience of threshold duration visual stimuli indicates visual perception is all or none

PubMed Central

Sekar, Krithiga; Findley, William M.; Poeppel, David; Llinás, Rodolfo R.

2013-01-01

At perceptual threshold, some stimuli are available for conscious access whereas others are not. Such threshold inputs are useful tools for investigating the events that separate conscious awareness from unconscious stimulus processing. Here, viewing unmasked, threshold-duration images was combined with recording magnetoencephalography to quantify differences among perceptual states, ranging from no awareness to ambiguity to robust perception. A four-choice scale was used to assess awareness: “didn’t see” (no awareness), “couldn’t identify” (awareness without identification), “unsure” (awareness with low certainty identification), and “sure” (awareness with high certainty identification). Stimulus-evoked neuromagnetic signals were grouped according to behavioral response choices. Three main cortical responses were elicited. The earliest response, peaking at ∼100 ms after stimulus presentation, showed no significant correlation with stimulus perception. A late response (∼290 ms) showed moderate correlation with stimulus awareness but could not adequately differentiate conscious access from its absence. By contrast, an intermediate response peaking at ∼240 ms was observed only for trials in which stimuli were consciously detected. That this signal was similar for all conditions in which awareness was reported is consistent with the hypothesis that conscious visual access is relatively sharply demarcated. PMID:23509248

Effects of ageing on orofacial fine force control and its relationship with parallel change in sensory perception.

PubMed

Etter, Nicole M; Mckeon, Patrick O; Dressler, Emily V; Andreatta, Richard D

2017-05-03

Current theoretical models suggest the importance of a bidirectional relationship between sensation and production in the vocal tract to maintain lifelong speech skills. The purpose of this study was to assess age-related changes in orofacial skilled force production and to begin defining the orofacial perception-action relationship in healthy adults. Low-level orofacial force control measures (reaction time, rise time, peak force, mean hold force (N) and force hold SD) were collected from 60 adults (19-84 years). Non-parametric Kruskal Wallis tests were performed to identify statistical differences between force and group demographics. Non-parametric Spearman's rank correlations were completed to compare force measures against previously published sensory data from the same cohort of participants. Significant group differences in force control were found for age, sex, speech usage and smoking status. Significant correlational relationships were identified between labial vibrotactile thresholds and several low-level force control measures collected during step and ramp-and-hold conditions. These findings demonstrate age-related alterations in orofacial force production. Furthermore, correlational analysis suggests as vibrotactile detection thresholds increase, the ability to maintain low-level force control accuracy decreases. Possible clinical applications and treatment consequences of these findings for speech disorders in the ageing population are provided.

The influence of informational masking on speech perception and pupil response in adults with hearing impairment.

PubMed

Koelewijn, Thomas; Zekveld, Adriana A; Festen, Joost M; Kramer, Sophia E

2014-03-01

A recent pupillometry study on adults with normal hearing indicates that the pupil response during speech perception (cognitive processing load) is strongly affected by the type of speech masker. The current study extends these results by recording the pupil response in 32 participants with hearing impairment (mean age 59 yr) while they were listening to sentences masked by fluctuating noise or a single-talker. Efforts were made to improve audibility of all sounds by means of spectral shaping. Additionally, participants performed tests measuring verbal working memory capacity, inhibition of interfering information in working memory, and linguistic closure. The results showed worse speech reception thresholds for speech masked by single-talker speech compared to fluctuating noise. In line with previous results for participants with normal hearing, the pupil response was larger when listening to speech masked by a single-talker compared to fluctuating noise. Regression analysis revealed that larger working memory capacity and better inhibition of interfering information related to better speech reception thresholds, but these variables did not account for inter-individual differences in the pupil response. In conclusion, people with hearing impairment show more cognitive load during speech processing when there is interfering speech compared to fluctuating noise.

Assessing spectral and temporal processing in children and adults using temporal modulation transfer function (TMTF), Iterated Ripple Noise (IRN) perception, and spectral ripple discrimination (SRD).

PubMed

Peter, Varghese; Wong, Kogo; Narne, Vijaya Kumar; Sharma, Mridula; Purdy, Suzanne C; McMahon, Catherine

2014-02-01

There are many clinically available tests for the assessment of auditory processing skills in children and adults. However, there is limited data available on the maturational effects on the performance on these tests. The current study investigated maturational effects on auditory processing abilities using three psychophysical measures: temporal modulation transfer function (TMTF), iterated ripple noise (IRN) perception, and spectral ripple discrimination (SRD). A cross-sectional study. Three groups of subjects were tested: 10 adults (18-30 yr), 10 older children (12-18 yr), and 10 young children (8-11 yr) Temporal envelope processing was measured by obtaining thresholds for amplitude modulation detection as a function of modulation frequency (TMTF; 4, 8, 16, 32, 64, and 128 Hz). Temporal fine structure processing was measured using IRN, and spectral processing was measured using SRD. The results showed that young children had significantly higher modulation thresholds at 4 Hz (TMTF) compared to the other two groups and poorer SRD scores compared to adults. The results on IRN did not differ across groups. The results suggest that different aspects of auditory processing mature at different age periods and these maturational effects need to be considered while assessing auditory processing in children. American Academy of Audiology.

Decomposing fear perception: A combination of psychophysics and neurometric modeling of fear perception.

PubMed

Forscher, Emily C; Zheng, Yan; Ke, Zijun; Folstein, Jonathan; Li, Wen

2016-10-01

Emotion perception is known to involve multiple operations and waves of analysis, but specific nature of these processes remains poorly understood. Combining psychophysical testing and neurometric analysis of event-related potentials (ERPs) in a fear detection task with parametrically varied fear intensities (N=45), we sought to elucidate key processes in fear perception. Building on psychophysics marking fear perception thresholds, our neurometric model fitting identified several putative operations and stages: four key processes arose in sequence following face presentation - fear-neutral categorization (P1 at 100ms), fear detection (P300 at 320ms), valuation (early subcomponent of the late positive potential/LPP at 400-500ms) and conscious awareness (late subcomponent LPP at 500-600ms). Furthermore, within-subject brain-behavior association suggests that initial emotion categorization was mandatory and detached from behavior whereas valuation and conscious awareness directly impacted behavioral outcome (explaining 17% and 31% of the total variance, respectively). The current study thus reveals the chronometry of fear perception, ascribing psychological meaning to distinct underlying processes. The combination of early categorization and late valuation of fear reconciles conflicting (categorical versus dimensional) emotion accounts, lending support to a hybrid model. Importantly, future research could specifically interrogate these psychological processes in various behaviors and psychopathologies (e.g., anxiety and depression). Copyright © 2016 Elsevier Ltd. All rights reserved.

Sensing the intruder: a quantitative threshold for recognition cues perception in honeybees

NASA Astrophysics Data System (ADS)

Cappa, Federico; Bruschini, Claudia; Cipollini, Maria; Pieraccini, Giuseppe; Cervo, Rita

2014-02-01

The ability to discriminate among nestmates and non-nestmate is essential to defend social insect colonies from intruders. Over the years, nestmate recognition has been extensively studied in the honeybee Apis mellifera; nevertheless, the quantitative perceptual aspects at the basis of the recognition system represent an unexplored subject in this species. To test the existence of a cuticular hydrocarbons' quantitative perception threshold for nestmate recognition cues, we conducted behavioural assays by presenting different amounts of a foreign forager's chemical profile to honeybees at the entrance of their colonies. We found an increase in the explorative and aggressive responses as the amount of cues increased based on a threshold mechanism, highlighting the importance of the quantitative perceptual features for the recognition processes in A. mellifera.

Melodic interval perception by normal-hearing listeners and cochlear implant users

PubMed Central

Luo, Xin; Masterson, Megan E.; Wu, Ching-Chih

2014-01-01

The perception of melodic intervals (sequential pitch differences) is essential to music perception. This study tested melodic interval perception in normal-hearing (NH) listeners and cochlear implant (CI) users. Melodic interval ranking was tested using an adaptive procedure. CI users had slightly higher interval ranking thresholds than NH listeners. Both groups' interval ranking thresholds, although not affected by root note, significantly increased with standard interval size and were higher for descending intervals than for ascending intervals. The pitch direction effect may be due to a procedural artifact or a difference in central processing. In another test, familiar melodies were played with all the intervals scaled by a single factor. Subjects rated how in tune the melodies were and adjusted the scaling factor until the melodies sounded the most in tune. CI users had lower final interval ratings and less change in interval rating as a function of scaling factor than NH listeners. For CI users, the root-mean-square error of the final scaling factors and the width of the interval rating function were significantly correlated with the average ranking threshold for ascending rather than descending intervals, suggesting that CI users may have focused on ascending intervals when rating and adjusting the melodies. PMID:25324084

Vibrotactile Presentation of Musical Notes to the Glabrous Skin for Adults with Normal Hearing or a Hearing Impairment: Thresholds, Dynamic Range and High-Frequency Perception

PubMed Central

Maté-Cid, Saúl; Fulford, Robert; Seiffert, Gary; Ginsborg, Jane

2016-01-01

Presentation of music as vibration to the skin has the potential to facilitate interaction between musicians with hearing impairments and other musicians during group performance. Vibrotactile thresholds have been determined to assess the potential for vibrotactile presentation of music to the glabrous skin of the fingertip, forefoot and heel. No significant differences were found between the thresholds for sinusoids representing notes between C1 and C6 when presented to the fingertip of participants with normal hearing and with a severe or profound hearing loss. For participants with normal hearing, thresholds for notes between C1 and C6 showed the characteristic U-shape curve for the fingertip, but not for the forefoot and heel. Compared to the fingertip, the forefoot had lower thresholds between C1 and C3, and the heel had lower thresholds between C1 and G2; this is attributed to spatial summation from the Pacinian receptors over the larger contactor area used for the forefoot and heel. Participants with normal hearing assessed the perception of high-frequency vibration using 1s sinusoids presented to the fingertip and were found to be more aware of transient vibration at the beginning and/or end of notes between G4 and C6 when stimuli were presented 10dB above threshold, rather than at threshold. An average of 94% of these participants reported feeling continuous vibration between G4 and G5 with stimuli presented 10dB above threshold. Based on the experimental findings and consideration of health effects relating to vibration exposure, a suitable range of notes for vibrotactile presentation of music is identified as being from C1 to G5. This is more limited than for human hearing but the fundamental frequencies of the human voice, and the notes played by many instruments, lie within it. However, the dynamic range might require compression to avoid the negative effects of amplitude on pitch perception. PMID:27191400

Influence of Passive Joint Stiffness on Proprioceptive Acuity in Individuals With Functional Instability of the Ankle.

PubMed

Marinho, Hellen Veloso Rocha; Amaral, Giovanna Mendes; de Souza Moreira, Bruno; Araújo, Vanessa Lara; Souza, Thales Rezende; Ocarino, Juliana Melo; da Fonseca, Sérgio Teixeira

2017-12-01

Study Design Controlled laboratory study, cross-sectional. Background Deficits in ankle proprioceptive acuity have been reported in persons with functional instability of the ankle. Passive stiffness has been proposed as a possible mechanism underlying proprioceptive acuity. Objective To compare proprioceptive acuity and passive ankle stiffness in persons with and without functional ankle instability, and to assess the influence of passive joint stiffness on proprioceptive acuity in persons with functional ankle instability. Methods A sample of 18 subjects with and 18 without complaints of functional ankle instability following lateral ankle sprain participated. An isokinetic dynamometer was used to compare motion perception threshold, passive position sense, and passive ankle stiffness between groups. To evaluate the influence of passive stiffness on proprioceptive acuity, individuals in the lateral functional ankle instability group were divided into 2 subgroups: "high" and "low" passive ankle stiffness. Results The functional ankle instability group exhibited increased motion perception threshold when compared with the corresponding limb of the control group. Between-group differences were not found for passive position sense and passive ankle stiffness. Those in the functional ankle instability group with higher passive ankle stiffness had smaller motion perception thresholds than those with lower passive ankle stiffness. Conclusion Unlike motion perception threshold, passive position sense is not affected by the presence of functional ankle instability. Passive ankle stiffness appears to influence proprioceptive acuity in persons with functional ankle instability. J Orthop Sports Phys Ther 2017;47(12):899-905. Epub 7 Oct 2017. doi:10.2519/jospt.2017.7030.

A Brief Mindfulness Meditation Training Increases Pain Threshold and Accelerates Modulation of Response to Tonic Pain in an Experimental Study.

PubMed

Reiner, Keren; Granot, Michal; Soffer, Eliran; Lipsitz, Joshua Dan

2016-04-01

Research shows that mindfulness meditation (MM) affects pain perception; however, studies have yet to measure patterns of change over time. We examined effects of MM on perception of experimental heat pain using multiple psychophysical indices, including pattern of change in response to tonic painful stimuli. We also tested the potential moderating role of baseline mindfulness. Forty participants were randomly assigned to a brief MM training or control group. We assessed: a) heat pain threshold (HPT), b) temperature which induces pain at a fixed, target intensity level, and c) response pattern over time to tonic heat pain. Compared to control group, the MM group showed increased HPT and more rapid attenuation of pain intensity for tonic pain stimuli. Moderation analyses indicated that baseline mindfulness moderated effects of MM on HPT. A brief MM intervention appears to affect perception of experimental pain both by increasing pain threshold and accelerating modulation of response. Findings may help elucidate mechanisms of MM for chronic pain. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Colour perception with changes in levels of illumination

NASA Astrophysics Data System (ADS)

Baah, Kwame F.; Green, Phil; Pointer, Michael

2012-01-01

The perceived colour of a stimulus depends on the conditions under which it is viewed. For colours employed as an important cue or identifier, such as signage and brand colours, colour reproduction tolerances are critically important. Typically, such stimuli would be judged using a known level of illumination but, in the target environment, the level of illumination used to view the samples may be entirely different. The effect of changes in the viewing condition on the perceptibility and acceptability of small colour differences should be understood when such tolerances and associated viewing conditions, are specified. A series of psychophysical experiments was conducted to determine whether changes in illumination level significantly alter acceptability and perceptibility thresholds of uniform colour stimuli. It was found that perceived colour discrimination thresholds varied by up to 2.0 ΔE00. For the perceptual correlate of hue however, this value could be of significance if the accepted error of colour difference was at the threshold, thereby yielding the possibility of rejection with changes in illumination level. Lightness and chroma on the other hand, exhibited greater tolerance and were less likely to be rejected with illuminance changes.

Dissatisfaction with own body makes patients with eating disorders more sensitive to pain

PubMed Central

Yamamotova, Anna; Bulant, Josef; Bocek, Vaclav; Papezova, Hana

2017-01-01

Body image represents a multidimensional concept including body image evaluation and perception of body appearance. Disturbances of body image perception are considered to be one of the central aspects of anorexia nervosa and bulimia nervosa. There is growing evidence that body image distortion can be associated with changes in pain perception. The aim of our study was to examine the associations between body image perception, body dissatisfaction, and nociception in women with eating disorders and age-matched healthy control women. We measured body dissatisfaction and pain sensitivity in 61 patients with Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition diagnoses of eating disorders (31 anorexia nervosa and 30 bulimia nervosa) and in 30 healthy women. Thermal pain threshold latencies were evaluated using an analgesia meter and body image perception and body dissatisfaction were assessed using Anamorphic Micro software (digital pictures of their own body distorted into larger-body and thinner-body images). Patients with eating disorders overestimated their body size in comparison with healthy controls, but the two groups did not differ in body dissatisfaction. In anorexia and bulimia patient groups, body dissatisfaction (calculated in pixels as desired size/true image size) correlated with pain threshold latencies (r=0.55, p=0.001), while between body image perception (determined as estimation size/true image size) and pain threshold, no correlation was found. Thus, we demonstrated that in patients with eating disorders, pain perception is significantly associated with emotional contrary to sensory (visual) processing of one’s own body image. The more the patients desired to be thin, the more pain-sensitive they were. Our findings based on some shared mechanisms of body dissatisfaction and pain perception support the significance of negative emotions specific for eating disorders and contribute to better understanding of the psychosomatic characteristics of this spectrum of illnesses. PMID:28761371

Between-Frequency and Between-Ear Gap Detections and Their Relation to Perception of Stop Consonants.

PubMed

Mori, Shuji; Oyama, Kazuki; Kikuchi, Yousuke; Mitsudo, Takako; Hirose, Nobuyuki

2015-01-01

The objective of this study was to examine the hypothesis that between-channel gap detection, which includes between-frequency and between-ear gap detection, and perception of stop consonants, which is mediated by the length of voice-onset time (VOT), share common mechanisms, namely relative-timing operation in monitoring separate perceptual channels. The authors measured gap detection thresholds and identification functions of /ba/ and /pa/ along VOT in 49 native young adult Japanese listeners. There were three gap detection tasks. In the between-frequency task, the leading and trailing markers differed in terms of center frequency (Fc). The leading marker was a broadband noise of 10 to 20,000 Hz. The trailing marker was a 0.5-octave band-passed noise of 1000-, 2000-, 4000-, or 8000-Hz Fc. In the between-ear task, the two markers were spectrally identical but presented to separate ears. In the within-frequency task, the two spectrally identical markers were presented to the same ear. The /ba/-/pa/ identification functions were obtained in a task in which the listeners were presented synthesized speech stimuli of varying VOTs from 10 to 46 msec and asked to identify them as /ba/ or /pa/. The between-ear gap thresholds were significantly positively correlated with the between-frequency gap thresholds (except those obtained with the trailing marker of 4000-Hz Fc). The between-ear gap thresholds were not significantly correlated with the within-frequency gap thresholds, which were significantly correlated with all the between-frequency gap thresholds. The VOT boundaries and slopes of /ba/-/pa/ identification functions were not significantly correlated with any of these gap thresholds. There was a close relation between the between-ear and between-frequency gap detection, supporting the view that these two types of gap detection share common mechanisms of between-channel gap detection. However, there was no evidence for a relation between the perception of stop consonants and the between-frequency/ear gap detection in native Japanese speakers.

Effects of Hearing Preservation on Psychophysical Responses to Cochlear Implant Stimulation

PubMed Central

Kang, Stephen Y.; Colesa, Deborah J.; Swiderski, Donald L.; Su, Gina L.; Raphael, Yehoash

2009-01-01

Previous studies have shown that residual acoustic hearing supplements cochlear implant function to improve speech recognition in noise as well as perception of music. The current study had two primary objectives. First, we sought to determine how cochlear implantation and electrical stimulation over a time period of 14 to 21 months influence cochlear structures such as hair cells and spiral ganglion neurons. Second, we sought to investigate whether the structures that provide acoustic hearing also affect the perception of electrical stimulation. We compared psychophysical responses to cochlear implant stimulation in two groups of adult guinea pigs. Group I (11 animals) received a cochlear implant in a previously untreated ear, while group II (ten animals) received a cochlear implant in an ear that had been previously infused with neomycin to destroy hearing. Psychophysical thresholds were measured in response to pulse-train and sinusoidal stimuli. Histological analysis of all group I animals and a subset of group II animals was performed. Nine of the 11 group I animals showed survival of the organ of Corti and spiral ganglion neurons adjacent to the electrode array. All group I animals showed survival of these elements in regions apical to the electrode array. Group II animals that were examined histologically showed complete loss of the organ of Corti in regions adjacent and apical to the electrode array and severe spiral ganglion neuron loss, consistent with previous reports for neomycin-treated ears. Behaviorally, group II animals had significantly lower thresholds than group I animals in response to 100 Hz sinusoidal stimuli. However, group I animals had significantly lower thresholds than group II animals in response to pulse-train stimuli (0.02 ms/phase; 156 to 5,000 pps). Additionally, the two groups showed distinct threshold versus pulse rate functions. We hypothesize that the differences in detection thresholds between groups are caused by the electrical activation of the hair cells in group I animals and/or differences between groups in the condition of the spiral ganglion neurons. PMID:19902297

Results of clinical olfactometric studies.

PubMed

Kittel, G

1976-09-01

A modification of a flow olfactometer with a new application appartus, with which "quasi-free" nasal respiration allows the elimination of adaptation without a special testing room, subsequent results using this device to examine olfactory thresholds before and after septum operations, as well as reference to threshold increases in 57 post-operative cases of cheilognathopalatoschisis are reported. An esthesio-neuroblastoma as well as the deformity syndrome with cheilognathopalatoschisis and encephalodystrophy are used as examples for combined olfactory transmission and perception disorders. Studies of 55 smokers with primary neurosensory disorders demonstrated a threefold increase in the olfactory threshold and an up to 50% decrease "fatique-time". A mean acetone deviation factor of 1.93 was seen in 100 students from 20-27 years of age before and after eating. Correspondingly, after a substantial breakfast and lunch, the olfactory threshold attained its maximum daily value within 90 minutes, much more pronounced than after intake of 80 grams of glucose solution. In contrast to the literature, the olfactory threshold was seen to continuously increase, dependent on age. Studies of the perceptive and recognition threshold on 100 normal individuals and 28 patients with hyposmia exhibited with 3 sigma, a significant difference. In patients with hyposmia, the absolute values for the two threshold types vary greatly, however not their deviation factors. More importance should be attached to the sense of smell as the so-called lesser senses give us the greatest pleasures.

Directional asymmetries and age effects in human self-motion perception.

PubMed

Roditi, Rachel E; Crane, Benjamin T

2012-06-01

Directional asymmetries in vestibular reflexes have aided the diagnosis of vestibular lesions; however, potential asymmetries in vestibular perception have not been well defined. This investigation sought to measure potential asymmetries in human vestibular perception. Vestibular perception thresholds were measured in 24 healthy human subjects between the ages of 21 and 68 years. Stimuli consisted of a single cycle of sinusoidal acceleration in a single direction lasting 1 or 2 s (1 or 0.5 Hz), delivered in sway (left-right), surge (forward-backward), heave (up-down), or yaw rotation. Subject identified self-motion directions were analyzed using a forced choice technique, which permitted thresholds to be independently determined for each direction. Non-motion stimuli were presented to measure possible response bias. A significant directional asymmetry in the dynamic response occurred in 27% of conditions tested within subjects, and in at least one type of motion in 92% of subjects. Directional asymmetries were usually consistent when retested in the same subject but did not occur consistently in one direction across the population with the exception of heave at 0.5 Hz. Responses during null stimuli presentation suggested that asymmetries were not due to biased guessing. Multiple models were applied and compared to determine if sensitivities were direction specific. Using Akaike information criterion, it was found that the model with direction specific sensitivities better described the data in 86% of runs when compared with a model that used the same sensitivity for both directions. Mean thresholds for yaw were 1.3±0.9°/s at 0.5 Hz and 0.9±0.7°/s at 1 Hz and were independent of age. Thresholds for surge and sway were 1.7±0.8 cm/s at 0.5 Hz and 0.7±0.3 cm/s at 1.0 Hz for subjects <50 and were significantly higher in subjects >50 years old. Heave thresholds were higher and were independent of age.

Cross-matching: a modified cross-correlation underlying threshold energy model and match-based depth perception

PubMed Central

Doi, Takahiro; Fujita, Ichiro

2014-01-01

Three-dimensional visual perception requires correct matching of images projected to the left and right eyes. The matching process is faced with an ambiguity: part of one eye's image can be matched to multiple parts of the other eye's image. This stereo correspondence problem is complicated for random-dot stereograms (RDSs), because dots with an identical appearance produce numerous potential matches. Despite such complexity, human subjects can perceive a coherent depth structure. A coherent solution to the correspondence problem does not exist for anticorrelated RDSs (aRDSs), in which luminance contrast is reversed in one eye. Neurons in the visual cortex reduce disparity selectivity for aRDSs progressively along the visual processing hierarchy. A disparity-energy model followed by threshold nonlinearity (threshold energy model) can account for this reduction, providing a possible mechanism for the neural matching process. However, the essential computation underlying the threshold energy model is not clear. Here, we propose that a nonlinear modification of cross-correlation, which we term “cross-matching,” represents the essence of the threshold energy model. We placed half-wave rectification within the cross-correlation of the left-eye and right-eye images. The disparity tuning derived from cross-matching was attenuated for aRDSs. We simulated a psychometric curve as a function of graded anticorrelation (graded mixture of aRDS and normal RDS); this simulated curve reproduced the match-based psychometric function observed in human near/far discrimination. The dot density was 25% for both simulation and observation. We predicted that as the dot density increased, the performance for aRDSs should decrease below chance (i.e., reversed depth), and the level of anticorrelation that nullifies depth perception should also decrease. We suggest that cross-matching serves as a simple computation underlying the match-based disparity signals in stereoscopic depth perception. PMID:25360107

Age-related changes in perception of movement in driving scenes.

PubMed

Lacherez, Philippe; Turner, Laura; Lester, Robert; Burns, Zoe; Wood, Joanne M

2014-07-01

Age-related changes in motion sensitivity have been found to relate to reductions in various indices of driving performance and safety. The aim of this study was to investigate the basis of this relationship in terms of determining which aspects of motion perception are most relevant to driving. Participants included 61 regular drivers (age range 22-87 years). Visual performance was measured binocularly. Measures included visual acuity, contrast sensitivity and motion sensitivity assessed using four different approaches: (1) threshold minimum drift rate for a drifting Gabor patch, (2) Dmin from a random dot display, (3) threshold coherence from a random dot display, and (4) threshold drift rate for a second-order (contrast modulated) sinusoidal grating. Participants then completed the Hazard Perception Test (HPT) in which they were required to identify moving hazards in videos of real driving scenes, and also a Direction of Heading task (DOH) in which they identified deviations from normal lane keeping in brief videos of driving filmed from the interior of a vehicle. In bivariate correlation analyses, all motion sensitivity measures significantly declined with age. Motion coherence thresholds, and minimum drift rate threshold for the first-order stimulus (Gabor patch) both significantly predicted HPT performance even after controlling for age, visual acuity and contrast sensitivity. Bootstrap mediation analysis showed that individual differences in DOH accuracy partly explained these relationships, where those individuals with poorer motion sensitivity on the coherence and Gabor tests showed decreased ability to perceive deviations in motion in the driving videos, which related in turn to their ability to detect the moving hazards. The ability to detect subtle movements in the driving environment (as determined by the DOH task) may be an important contributor to effective hazard perception, and is associated with age, and an individuals' performance on tests of motion sensitivity. The locus of the processing deficits appears to lie in first-order, rather than second-order motion pathways. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

Auditory enhancement of visual perception at threshold depends on visual abilities.

PubMed

Caclin, Anne; Bouchet, Patrick; Djoulah, Farida; Pirat, Elodie; Pernier, Jacques; Giard, Marie-Hélène

2011-06-17

Whether or not multisensory interactions can improve detection thresholds, and thus widen the range of perceptible events is a long-standing debate. Here we revisit this question, by testing the influence of auditory stimuli on visual detection threshold, in subjects exhibiting a wide range of visual-only performance. Above the perceptual threshold, crossmodal interactions have indeed been reported to depend on the subject's performance when the modalities are presented in isolation. We thus tested normal-seeing subjects and short-sighted subjects wearing their usual glasses. We used a paradigm limiting potential shortcomings of previous studies: we chose a criterion-free threshold measurement procedure and precluded exogenous cueing effects by systematically presenting a visual cue whenever a visual target (a faint Gabor patch) might occur. Using this carefully controlled procedure, we found that concurrent sounds only improved visual detection thresholds in the sub-group of subjects exhibiting the poorest performance in the visual-only conditions. In these subjects, for oblique orientations of the visual stimuli (but not for vertical or horizontal targets), the auditory improvement was still present when visual detection was already helped with flanking visual stimuli generating a collinear facilitation effect. These findings highlight that crossmodal interactions are most efficient to improve perceptual performance when an isolated modality is deficient. Copyright © 2011 Elsevier B.V. All rights reserved.

Neural Activity Patterns in the Human Brain Reflect Tactile Stickiness Perception.

PubMed

Kim, Junsuk; Yeon, Jiwon; Ryu, Jaekyun; Park, Jang-Yeon; Chung, Soon-Cheol; Kim, Sung-Phil

2017-01-01

Our previous human fMRI study found brain activations correlated with tactile stickiness perception using the uni-variate general linear model (GLM) (Yeon et al., 2017). Here, we conducted an in-depth investigation on neural correlates of sticky sensations by employing a multivoxel pattern analysis (MVPA) on the same dataset. In particular, we statistically compared multi-variate neural activities in response to the three groups of sticky stimuli: A supra-threshold group including a set of sticky stimuli that evoked vivid sticky perception; an infra-threshold group including another set of sticky stimuli that barely evoked sticky perception; and a sham group including acrylic stimuli with no physically sticky property. Searchlight MVPAs were performed to search for local activity patterns carrying neural information of stickiness perception. Similar to the uni-variate GLM results, significant multi-variate neural activity patterns were identified in postcentral gyrus, subcortical (basal ganglia and thalamus), and insula areas (insula and adjacent areas). Moreover, MVPAs revealed that activity patterns in posterior parietal cortex discriminated the perceptual intensities of stickiness, which was not present in the uni-variate analysis. Next, we applied a principal component analysis (PCA) to the voxel response patterns within identified clusters so as to find low-dimensional neural representations of stickiness intensities. Follow-up clustering analyses clearly showed separate neural grouping configurations between the Supra- and Infra-threshold groups. Interestingly, this neural categorization was in line with the perceptual grouping pattern obtained from the psychophysical data. Our findings thus suggest that different stickiness intensities would elicit distinct neural activity patterns in the human brain and may provide a neural basis for the perception and categorization of tactile stickiness.

Neural Activity Patterns in the Human Brain Reflect Tactile Stickiness Perception

PubMed Central

Kim, Junsuk; Yeon, Jiwon; Ryu, Jaekyun; Park, Jang-Yeon; Chung, Soon-Cheol; Kim, Sung-Phil

2017-01-01

Our previous human fMRI study found brain activations correlated with tactile stickiness perception using the uni-variate general linear model (GLM) (Yeon et al., 2017). Here, we conducted an in-depth investigation on neural correlates of sticky sensations by employing a multivoxel pattern analysis (MVPA) on the same dataset. In particular, we statistically compared multi-variate neural activities in response to the three groups of sticky stimuli: A supra-threshold group including a set of sticky stimuli that evoked vivid sticky perception; an infra-threshold group including another set of sticky stimuli that barely evoked sticky perception; and a sham group including acrylic stimuli with no physically sticky property. Searchlight MVPAs were performed to search for local activity patterns carrying neural information of stickiness perception. Similar to the uni-variate GLM results, significant multi-variate neural activity patterns were identified in postcentral gyrus, subcortical (basal ganglia and thalamus), and insula areas (insula and adjacent areas). Moreover, MVPAs revealed that activity patterns in posterior parietal cortex discriminated the perceptual intensities of stickiness, which was not present in the uni-variate analysis. Next, we applied a principal component analysis (PCA) to the voxel response patterns within identified clusters so as to find low-dimensional neural representations of stickiness intensities. Follow-up clustering analyses clearly showed separate neural grouping configurations between the Supra- and Infra-threshold groups. Interestingly, this neural categorization was in line with the perceptual grouping pattern obtained from the psychophysical data. Our findings thus suggest that different stickiness intensities would elicit distinct neural activity patterns in the human brain and may provide a neural basis for the perception and categorization of tactile stickiness. PMID:28936171

Perception of faces in schizophrenia: Subjective (self-report) vs. objective (psychophysics) assessments.

PubMed

Chen, Yue; Ekstrom, Tor

2016-05-01

Face perception impairment in schizophrenia has been demonstrated, mostly through experimental studies. How this laboratory-defined behavioral impairment is associated with patients' perceptual experience of various faces in everyday life is however unclear. This question is important because a first-person account of face perception has direct consequences on social functioning of patients. In this study, we adapted and administered a self-reported questionnaire on narrative perceptual experience of faces along with psychophysical assessments of face perception in schizophrenia. The self-reported questionnaire includes six rating items of face-related functioning in everyday life, providing a subjective measure of face perception. The psychophysical assessment determines perceptual threshold for discriminating different facial identities, providing an objective measure of face perception. Compared to controls (n = 25), patients (n = 35) showed significantly lower scores (worse performance) in the subjective assessment and significantly higher thresholds (worse performance) in the objective assessment. The subjective and objective face perception assessments were moderately correlated in controls but not in patients. The subjective face perception assessments were significantly correlated with measurements of a social cognitive ability (Theory of Mind), again in controls but not in patients. These results suggest that in schizophrenia the quality of face-related functioning in everyday life is degraded and the role that basic face discrimination capacity plays in face-related everyday functioning is disrupted. Copyright © 2016 Elsevier Ltd. All rights reserved.

Perception of faces in schizophrenia: Subjective (self-report) vs. objective (psychophysics) assessments

PubMed Central

Chen, Yue; Ekstrom, Tor

2016-01-01

Objectives Face perception impairment in schizophrenia has been demonstrated, mostly through experimental studies. How this laboratory-defined behavioral impairment is associated with patients’ perceptual experience of various faces in everyday life is however unclear. This question is important because a first-person account of face perception has direct consequences on social functioning of patients. In this study, we adapted and administered a self-reported questionnaire on narrative perceptual experience of faces along with psychophysical assessments of face perception in schizophrenia. Methods The self-reported questionnaire includes six rating items of face-related functioning in everyday life, providing a subjective measure of face perception. The psychophysical assessment determines perceptual threshold for discriminating different facial identities, providing an objective measure of face perception. Results Compared to controls (n=25), patients (n=35) showed significantly lower scores (worse performance) in the subjective assessment and significantly higher thresholds (worse performance) in the objective assessment. The subjective and objective face perception assessments were moderately correlated in controls but not in patients. The subjective face perception assessments were significantly correlated with measurements of a social cognitive ability (Theory of Mind), again in controls but not in patients. Conclusion These results suggest that in schizophrenia the quality of face-related functioning in everyday life is degraded and the role that basic face discrimination capacity plays in face-related everyday functioning is disrupted. PMID:26938027

Vibrotactile perception threshold measurements for diagnosis of sensory neuropathy. Description of a reference population.

PubMed

Lundström, R; Strömberg, T; Lundborg, G

1992-01-01

Recognition of the fact that impairment of the tactile sense may occur independently of other disturbances in the vibration syndrome has rekindled an interest in developing a diagnostic method for early detection of vibration-induced neuropathy. There is also evidence suggesting that vibrotactile measurements represent a valuable diagnostic tool in compressive neuropathies, such as the carpal tunnel syndrome. The method may also become useful for diagnosing sensory neuropathies caused by other factors, such as solvents, pesticides, heavy metals, alcoholism, and diabetes. However, before vibrotactile measurement can be accepted and established as a tool for clinical diagnostic purposes, for screening, and in research, the level and the shape of the normal threshold curve have to be specified. With the purpose of assembling normative data, the vibrotactile perception thresholds (8-500 Hz) of the right index fingertip were measured in 171 healthy males (19-75 years) not exposed to vibration. A Békésy audiometer was modified to operate in combination with a vibration exciter, instead of headphones, at frequencies lower than usual (8-500 Hz). The results showed that the perception thresholds increased from about 100 dB to about 140 dB (rel. 10(-6) m/s2rms) as a function of frequency and age. The frequency-dependent changes were not linear, however, but displayed a peak in sensitivity at 125 Hz. Threshold changes due to aging were most pronounced at the highest frequencies. It is of the utmost importance that these natural changes are taken into account when making comparisons between groups or individuals.

Psycho acoustical Measures in Individuals with Congenital Visual Impairment.

PubMed

Kumar, Kaushlendra; Thomas, Teenu; Bhat, Jayashree S; Ranjan, Rajesh

2017-12-01

In congenital visual impaired individuals one modality is impaired (visual modality) this impairment is compensated by other sensory modalities. There is evidence that visual impaired performed better in different auditory task like localization, auditory memory, verbal memory, auditory attention, and other behavioural tasks when compare to normal sighted individuals. The current study was aimed to compare the temporal resolution, frequency resolution and speech perception in noise ability in individuals with congenital visual impaired and normal sighted. Temporal resolution, frequency resolution, and speech perception in noise were measured using MDT, GDT, DDT, SRDT, and SNR50 respectively. Twelve congenital visual impaired participants with age range of 18 to 40 years were taken and equal in number with normal sighted participants. All the participants had normal hearing sensitivity with normal middle ear functioning. Individual with visual impairment showed superior threshold in MDT, SRDT and SNR50 as compared to normal sighted individuals. This may be due to complexity of the tasks; MDT, SRDT and SNR50 are complex tasks than GDT and DDT. Visual impairment showed superior performance in auditory processing and speech perception with complex auditory perceptual tasks.

Audiovisual integration in children listening to spectrally degraded speech.

PubMed

Maidment, David W; Kang, Hi Jee; Stewart, Hannah J; Amitay, Sygal

2015-02-01

The study explored whether visual information improves speech identification in typically developing children with normal hearing when the auditory signal is spectrally degraded. Children (n=69) and adults (n=15) were presented with noise-vocoded sentences from the Children's Co-ordinate Response Measure (Rosen, 2011) in auditory-only or audiovisual conditions. The number of bands was adaptively varied to modulate the degradation of the auditory signal, with the number of bands required for approximately 79% correct identification calculated as the threshold. The youngest children (4- to 5-year-olds) did not benefit from accompanying visual information, in comparison to 6- to 11-year-old children and adults. Audiovisual gain also increased with age in the child sample. The current data suggest that children younger than 6 years of age do not fully utilize visual speech cues to enhance speech perception when the auditory signal is degraded. This evidence not only has implications for understanding the development of speech perception skills in children with normal hearing but may also inform the development of new treatment and intervention strategies that aim to remediate speech perception difficulties in pediatric cochlear implant users.

Sensory nerve action potentials and sensory perception in women with arthritis of the hand.

PubMed

Calder, Kristina M; Martin, Alison; Lydiate, Jessica; MacDermid, Joy C; Galea, Victoria; MacIntyre, Norma J

2012-05-10

Arthritis of the hand can limit a person's ability to perform daily activities. Whether or not sensory deficits contribute to the disability in this population remains unknown. The primary purpose of this study was to determine if women with osteoarthritis (OA) or rheumatoid arthritis (RA) of the hand have sensory impairments. Sensory function in the dominant hand of women with hand OA or RA and healthy women was evaluated by measuring sensory nerve action potentials (SNAPs) from the median, ulnar and radial nerves, sensory mapping (SM), and vibratory and current perception thresholds (VPT and CPT, respectively) of the second and fifth digits. All SNAP amplitudes were significantly lower for the hand OA and hand RA groups compared with the healthy group (p < 0.05). No group differences were found for SNAP conduction velocities, SM, VPT, and CPT. We propose, based on these findings, that women with hand OA or RA may have axonal loss of sensory fibers in the median, ulnar and radial nerves. Less apparent were losses in conduction speed or sensory perception.

Sensory nerve action potentials and sensory perception in women with arthritis of the hand

PubMed Central

2012-01-01

Background Arthritis of the hand can limit a person’s ability to perform daily activities. Whether or not sensory deficits contribute to the disability in this population remains unknown. The primary purpose of this study was to determine if women with osteoarthritis (OA) or rheumatoid arthritis (RA) of the hand have sensory impairments. Methods Sensory function in the dominant hand of women with hand OA or RA and healthy women was evaluated by measuring sensory nerve action potentials (SNAPs) from the median, ulnar and radial nerves, sensory mapping (SM), and vibratory and current perception thresholds (VPT and CPT, respectively) of the second and fifth digits. Results All SNAP amplitudes were significantly lower for the hand OA and hand RA groups compared with the healthy group (p < 0.05). No group differences were found for SNAP conduction velocities, SM, VPT, and CPT. Discussion We propose, based on these findings, that women with hand OA or RA may have axonal loss of sensory fibers in the median, ulnar and radial nerves. Less apparent were losses in conduction speed or sensory perception. PMID:22575001

Inconsistent Effect of Arousal on Early Auditory Perception

PubMed Central

Bolders, Anna C.; Band, Guido P. H.; Stallen, Pieter Jan M.

2017-01-01

Mood has been shown to influence cognitive performance. However, little is known about the influence of mood on sensory processing, specifically in the auditory domain. With the current study, we sought to investigate how auditory processing of neutral sounds is affected by the mood state of the listener. This was tested in two experiments by measuring masked-auditory detection thresholds before and after a standard mood-induction procedure. In the first experiment (N = 76), mood was induced by imagining a mood-appropriate event combined with listening to mood inducing music. In the second experiment (N = 80), imagining was combined with affective picture viewing to exclude any possibility of confounding the results by acoustic properties of the music. In both experiments, the thresholds were determined by means of an adaptive staircase tracking method in a two-interval forced-choice task. Masked detection thresholds were compared between participants in four different moods (calm, happy, sad, and anxious), which enabled differentiation of mood effects along the dimensions arousal and pleasure. Results of the two experiments were analyzed both in separate analyses and in a combined analysis. The first experiment showed that, while there was no impact of pleasure level on the masked threshold, lower arousal was associated with lower threshold (higher masked sensitivity). However, as indicated by an interaction effect between experiment and arousal, arousal did have a different effect on the threshold in Experiment 2. Experiment 2 showed a trend of arousal in opposite direction. These results show that the effect of arousal on auditory-masked sensitivity may depend on the modality of the mood-inducing stimuli. As clear conclusions regarding the genuineness of the arousal effect on the masked threshold cannot be drawn, suggestions for further research that could clarify this issue are provided. PMID:28424639

Thermal detection thresholds in 5-year-old preterm born children; IQ does matter.

PubMed

de Graaf, Joke; Valkenburg, Abraham J; Tibboel, Dick; van Dijk, Monique

2012-07-01

Experiencing pain at newborn age may have consequences on one's somatosensory perception later in life. Children's perception for cold and warm stimuli may be determined with the Thermal Sensory Analyzer (TSA) device by two different methods. This pilot study in 5-year-old children born preterm aimed at establishing whether the TSA method of limits, which is dependent of reaction time, and the method of levels, which is independent of reaction time, would yield different cold and warm detection thresholds. The second aim was to establish possible associations between intellectual ability and the detection thresholds obtained with either method. A convenience sample was drawn from the participants in an ongoing 5-year follow-up study of a randomized controlled trial on effects of morphine during mechanical ventilation. Thresholds were assessed using both methods and statistically compared. Possible associations between the child's intelligence quotient (IQ) and threshold levels were analyzed. The method of levels yielded more sensitive thresholds than did the method of limits, i.e. mean (SD) cold detection thresholds: 30.3 (1.4) versus 28.4 (1.7) (Cohen'sd=1.2, P=0.001) and warm detection thresholds; 33.9 (1.9) versus 35.6 (2.1) (Cohen's d=0.8, P=0.04). IQ was statistically significantly associated only with the detection thresholds obtained with the method of limits (cold: r=0.64, warm: r=-0.52). The TSA method of levels, is to be preferred over the method of limits in 5-year-old preterm born children, as it establishes more sensitive detection thresholds and is independent of IQ. Copyright © 2011 Elsevier Ltd. All rights reserved.

Aging: Sensitivity versus Criterion in Taste Perception.

ERIC Educational Resources Information Center

Kushnir, T.; Shapira, N.

1983-01-01

Employed the signal-detection paradigm as a model for investigating age-related biological versus cognitive effects on perceptual behavior. Old and young subjects reported the presence or absence of sugar in threshold level solutions and tap water. Older subjects displayed a higher detection threshold and obtained a stricter criterion of decision.…

Sex differences in thermal detection and thermal pain threshold and the thermal grill illusion: a psychophysical study in young volunteers.

PubMed

Averbeck, Beate; Seitz, Lena; Kolb, Florian P; Kutz, Dieter F

2017-09-01

Sex-related differences in human thermal and pain sensitivity are the subject of controversial discussion. The goal of this study in a large number of subjects was to investigate sex differences in thermal and thermal pain perception and the thermal grill illusion (TGI) as a phenomenon reflecting crosstalk between the thermoreceptive and nociceptive systems. The thermal grill illusion is a sensation of strong, but not necessarily painful, heat often preceded by transient cold upon skin contact with spatially interlaced innocuous warm and cool stimuli. The TGI was studied in a group of 78 female and 58 male undergraduate students and was evoked by placing the palm of the right hand on the thermal grill (20/40 °C interleaved stimulus). Sex-related thermal perception was investigated by a retrospective analysis of thermal detection and thermal pain threshold data that had been measured in student laboratory courses over 5 years (776 female and 476 male undergraduate students) using the method of quantitative sensory testing (QST). To analyse correlations between thermal pain sensitivity and the TGI, thermal pain threshold and the TGI were determined in a group of 20 female and 20 male undergraduate students. The TGI was more pronounced in females than males. Females were more sensitive with respect to thermal detection and thermal pain thresholds. Independent of sex, thermal detection thresholds were dependent on the baseline temperature with a specific progression of an optimum curve for cold detection threshold versus baseline temperature. The distribution of cold pain thresholds was multi-modal and sex-dependent. The more pronounced TGI in females correlated with higher cold sensitivity and cold pain sensitivity in females than in males. Our finding that thermal detection threshold not only differs between the sexes but is also dependent on the baseline temperature reveals a complex processing of "cold" and "warm" inputs in thermal perception. The results of the TGI experiment support the assumption that sex differences in cold-related thermoreception are responsible for sex differences in the TGI.

The effects of noise exposure and musical training on suprathreshold auditory processing and speech perception in noise.

PubMed

Yeend, Ingrid; Beach, Elizabeth Francis; Sharma, Mridula; Dillon, Harvey

2017-09-01

Recent animal research has shown that exposure to single episodes of intense noise causes cochlear synaptopathy without affecting hearing thresholds. It has been suggested that the same may occur in humans. If so, it is hypothesized that this would result in impaired encoding of sound and lead to difficulties hearing at suprathreshold levels, particularly in challenging listening environments. The primary aim of this study was to investigate the effect of noise exposure on auditory processing, including the perception of speech in noise, in adult humans. A secondary aim was to explore whether musical training might improve some aspects of auditory processing and thus counteract or ameliorate any negative impacts of noise exposure. In a sample of 122 participants (63 female) aged 30-57 years with normal or near-normal hearing thresholds, we conducted audiometric tests, including tympanometry, audiometry, acoustic reflexes, otoacoustic emissions and medial olivocochlear responses. We also assessed temporal and spectral processing, by determining thresholds for detection of amplitude modulation and temporal fine structure. We assessed speech-in-noise perception, and conducted tests of attention, memory and sentence closure. We also calculated participants' accumulated lifetime noise exposure and administered questionnaires to assess self-reported listening difficulty and musical training. The results showed no clear link between participants' lifetime noise exposure and performance on any of the auditory processing or speech-in-noise tasks. Musical training was associated with better performance on the auditory processing tasks, but not the on the speech-in-noise perception tasks. The results indicate that sentence closure skills, working memory, attention, extended high frequency hearing thresholds and medial olivocochlear suppression strength are important factors that are related to the ability to process speech in noise. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Pain perception studies in tension-type headache.

PubMed

Bezov, David; Ashina, Sait; Jensen, Rigmor; Bendtsen, Lars

2011-02-01

Tension-type headache (TTH) is a disorder with high prevalence and significant impact on society. Understanding of pathophysiology of TTH is paramount for development of effective treatments and prevention of chronification of TTH. Our aim was to review the findings from pain perception studies of pathophysiology of TTH as well as to review the research of pathophysiology of TTH. Pain perception studies such as measurement of muscle tenderness, pain detection thresholds, pain tolerance thresholds, pain response to suprathreshold stimulation, temporal summation and diffuse noxious inhibitory control (DNIC) have played a central role in elucidating the pathophysiology of TTH. It has been demonstrated that continuous nociceptive input from peripheral myofascial structures may induce central sensitization and thereby chronification of the headache. Measurements of pain tolerance thresholds and suprathreshold stimulation have shown presence of generalized hyperalgesia in chronic tension-type headache (CTTH) patients, while DNIC function has been shown to be reduced in CTTH. One imaging study showed loss of gray matter structures involved in pain processing in CTTH patients. Future studies should aim to integrate pain perception and imaging to confirm this finding. Pharmacological studies have shown that drugs like tricyclic anti-depressant amitriptyline and nitric oxide synthase inhibitors can reverse central sensitization and the chronicity of headache. Finally, low frequency electrical stimulation has been shown to rapidly reverse central sensitization and may be a new modality in treatment of CTTH and other chronic pain disorders. © 2010 American Headache Society.

Comparing esthetic smile perceptions among laypersons with and without orthodontic treatment experience and dentists

PubMed Central

An, Seong-Mu; Choi, Sun-Young; Chung, Young-Wook; Jang, Tae-Ho

2014-01-01

Objective The purpose of this study was to examine whether orthodontic treatment experience affects the individual's perception of smile esthetics and to evaluate differences among orthodontically treated laypersons, non-treated laypersons, and dentists by using computerized image alterations. Methods A photograph of a woman's smile was digitally altered using a software image editing program. The alterations involved gingival margin height, crown width and length, incisal plane canting, and dental midline of the maxillary anterior teeth. Three groups of raters (orthodontically treated laypersons, non-treated laypersons, and dentists) evaluated the original and altered images using a visual analog scale. Results The threshold for detecting changes in maxillary central incisor gingival margin height among laypersons was 1.5 mm; the threshold of dentists, who were more perceptive, was 1.0 mm. For maxillary lateral incisor crown width and height, the threshold of all three groups was 3.0 mm. Canting of the incisal plane was perceived when the canting was 3.0 mm among non-treated laypersons, 2.0 mm among treated laypersons, and 1.0 mm among dentists. Non-treated laypersons could not perceive dental midline shifts; however, treated laypersons and dentists perceived them when the shift was ≥ 3.0 mm. Conclusions Laypersons with and without orthodontic treatment experience and dentists have different perceptions of smile esthetics. Orthodontically treated laypersons were more critical than non-treated laypersons regarding incisal plane canting and dental midline shifts. Based on these findings, it is suggested that orthodontic treatment experience improved the esthetic perceptions of laypersons. PMID:25473645

Intonation Processing in Congenital Amusia: Discrimination, Identification and Imitation

ERIC Educational Resources Information Center

Liu, Fang; Patel, Aniruddh D.; Fourcin, Adrian; Stewart, Lauren

2010-01-01

This study investigated whether congenital amusia, a neuro-developmental disorder of musical perception, also has implications for speech intonation processing. In total, 16 British amusics and 16 matched controls completed five intonation perception tasks and two pitch threshold tasks. Compared with controls, amusics showed impaired performance…

Multidisciplinary Child Protection Decision Making About Physical Abuse: Determining Substantiation Thresholds and Biases

PubMed Central

Jent, Jason F.; Eaton, Cyd K.; Knickerbocker, Lauren; Lambert, Walter F.; Merrick, Melissa T.; Dandes, Susan K.

2011-01-01

The current study examined the threshold at which multidisciplinary child protection team (CPT) professionals substantiate physical abuse allegations and the extent that they utilize potentially biased constructs in their decision making when presented with the same case evidence. State legal definitions of child maltreatment are broad. Therefore, the burden of interpretation is largely on CPT professionals who must determine at what threshold physical acts by parents surpass corporal discipline and constitute child physical abuse. Biased or subjective decisions may be made if certain case-specific characteristics or CPT professionals’ personal characteristics are used in making physical abuse determinations. Case vignettes with visual depictions of inflicted injuries were sent to CPT professionals in Florida and their substantiation decisions, personal beliefs about corporal discipline, and coercive discipline were collected. Results of the study demonstrated relatively high agreement among professionals across vignettes about what constitutes physical abuse. Further, CPT professionals strongly considered their perceptions of the severity of inflicted injuries in substantiation decisions. Although case specific characteristics did not bias decisions in a systematic way, some CPT professional characteristics influenced the substantiation of physical abuse. Practice implications and future directions of research are discussed. PMID:21804681

[Relationship between Occlusal Discomfort Syndrome and Occlusal Threshold].

PubMed

Munakata, Motohiro; Ono, Yumie; Hayama, Rika; Kataoka, Kanako; Ikuta, Ryuhei; Tamaki, Katsushi

2016-03-01

Occlusal dysesthesia has been defined as persistent uncomfortable feelings of intercuspal position continuing for more than 6 months without evidence of physical occlusal discrepancy. The problem often occurs after occlusal intervention by dental care. Although various dental treatments (e. g. occlusal adjustment, orthodontic treatment and prosthetic reconstruction) are attempted to solve occlusal dysesthesia, they rarely reach a satisfactory result, neither for patients nor dentists. In Japan, these symptoms are defined by the term "Occlusal discomfort syndrome" (ODS). The aim of this study was to investigate the characteristics of ODS with the simple occlusal sensory perceptive and discriminative test. Twenty-one female dental patients with ODS (mean age 55.8 ± 19.2 years) and 21 age- and gender-matched dental patients without ODS (mean age 53.1 ± 16.8 years) participated in the study. Upon grinding occlusal registration foils that were stacked to different thicknesses, participants reported the thicknesses at which they recognized the foils (recognition threshold) and felt discomfort (discomfort threshold). Although there was no significant difference in occlusal recognition thresholds between the two patient groups, the discomfort threshold was significantly smaller in the patients with ODS than in those without ODS. Moreover, the recognition threshold showed an age-dependent increase in patients without ODS, whereas it remained comparable between the younger (< 60 years old) and elderly (60 years old or more) patient subgroups with ODS. These results suggest that occlusal discomfort threshold rather than recognition threshold is an issue in ODS. The foil grinding procedure is a simple and useful method to evaluate occlusal perceptive and discriminative abilities in patients with ODS.

Effect of skin-transmitted vibration enhancement on vibrotactile perception.

PubMed

Tanaka, Yoshihiro; Ueda, Yuichiro; Sano, Akihito

2015-06-01

Vibration on skin elicited by the mechanical interaction of touch between the skin and an object propagates to skin far from the point of contact. This paper investigates the effect of skin-transmitted vibration on vibrotactile perception. To enhance the transmission of high-frequency vibration on the skin, stiff tape was attached to the skin so that the tape covered the bottom surface of the index finger from the periphery of the distal interphalangeal joint to the metacarpophalangeal joint. Two psychophysical experiments with high-frequency vibrotactile stimuli of 250 Hz were conducted. In the psychophysical experiments, discrimination and detection thresholds were estimated and compared between conditions of the presence or the absence of the tape (normal bare finger). A method of limits was applied for the detection threshold estimation, and the discrimination task using a reference stimulus and six test stimuli with different amplitudes was applied for the discrimination threshold estimation. The stimulation was given to bare fingertips of participants. Result showed that the detection threshold was enhanced by attaching the tape, and the discrimination threshold enhancement by attaching the tape was confirmed for participants who have relatively large discrimination threshold under normal bare finger. Then, skin-transmitted vibration was measured with an accelerometer with the psychophysical experiments. Result showed that the skin-transmitted vibration when the tape was attached to the skin was larger than that when normal bare skin. There is a correlation between the increase in skin-transmitted vibration and the enhancement of the discrimination threshold.

Neuronal detection thresholds during vestibular compensation: contributions of response variability and sensory substitution.

PubMed

Jamali, Mohsen; Mitchell, Diana E; Dale, Alexis; Carriot, Jerome; Sadeghi, Soroush G; Cullen, Kathleen E

2014-04-01

The vestibular system is responsible for processing self-motion, allowing normal subjects to discriminate the direction of rotational movements as slow as 1-2 deg s(-1). After unilateral vestibular injury patients' direction-discrimination thresholds worsen to ∼20 deg s(-1), and despite some improvement thresholds remain substantially elevated following compensation. To date, however, the underlying neural mechanisms of this recovery have not been addressed. Here, we recorded from first-order central neurons in the macaque monkey that provide vestibular information to higher brain areas for self-motion perception. Immediately following unilateral labyrinthectomy, neuronal detection thresholds increased by more than two-fold (from 14 to 30 deg s(-1)). While thresholds showed slight improvement by week 3 (25 deg s(-1)), they never recovered to control values - a trend mirroring the time course of perceptual thresholds in patients. We further discovered that changes in neuronal response variability paralleled changes in sensitivity for vestibular stimulation during compensation, thereby causing detection thresholds to remain elevated over time. However, we found that in a subset of neurons, the emergence of neck proprioceptive responses combined with residual vestibular modulation during head-on-body motion led to better neuronal detection thresholds. Taken together, our results emphasize that increases in response variability to vestibular inputs ultimately constrain neural thresholds and provide evidence that sensory substitution with extravestibular (i.e. proprioceptive) inputs at the first central stage of vestibular processing is a neural substrate for improvements in self-motion perception following vestibular loss. Thus, our results provide a neural correlate for the patient benefits provided by rehabilitative strategies that take advantage of the convergence of these multisensory cues.

Neuronal detection thresholds during vestibular compensation: contributions of response variability and sensory substitution

PubMed Central

Jamali, Mohsen; Mitchell, Diana E; Dale, Alexis; Carriot, Jerome; Sadeghi, Soroush G; Cullen, Kathleen E

2014-01-01

The vestibular system is responsible for processing self-motion, allowing normal subjects to discriminate the direction of rotational movements as slow as 1–2 deg s−1. After unilateral vestibular injury patients’ direction–discrimination thresholds worsen to ∼20 deg s−1, and despite some improvement thresholds remain substantially elevated following compensation. To date, however, the underlying neural mechanisms of this recovery have not been addressed. Here, we recorded from first-order central neurons in the macaque monkey that provide vestibular information to higher brain areas for self-motion perception. Immediately following unilateral labyrinthectomy, neuronal detection thresholds increased by more than two-fold (from 14 to 30 deg s−1). While thresholds showed slight improvement by week 3 (25 deg s−1), they never recovered to control values – a trend mirroring the time course of perceptual thresholds in patients. We further discovered that changes in neuronal response variability paralleled changes in sensitivity for vestibular stimulation during compensation, thereby causing detection thresholds to remain elevated over time. However, we found that in a subset of neurons, the emergence of neck proprioceptive responses combined with residual vestibular modulation during head-on-body motion led to better neuronal detection thresholds. Taken together, our results emphasize that increases in response variability to vestibular inputs ultimately constrain neural thresholds and provide evidence that sensory substitution with extravestibular (i.e. proprioceptive) inputs at the first central stage of vestibular processing is a neural substrate for improvements in self-motion perception following vestibular loss. Thus, our results provide a neural correlate for the patient benefits provided by rehabilitative strategies that take advantage of the convergence of these multisensory cues. PMID:24366259

Threshold dose for discrimination of nicotine via cigarette smoking.

PubMed

Perkins, Kenneth A; Kunkle, Nicole; Karelitz, Joshua L; Michael, Valerie C; Donny, Eric C

2016-06-01

The lowest nicotine threshold "dose" in cigarettes discriminated from a cigarette containing virtually no nicotine may help inform the minimum dose maintaining dependence. Spectrum research cigarettes (from NIDA) differing in nicotine content were used to evaluate a procedure to determine discrimination thresholds. Dependent smokers (n = 18; 13 M, 5 F) were tested on ability to discriminate cigarettes with nicotine contents of 11, 5, 2.4, and 1.3 mg/g, one per session, from the "ultralow" cigarette with 0.4 mg/g, after having discriminated 16 mg/g from 0.4 mg/g (all had 9-10 mg "tar"). Exposure to each was limited to 4 puffs/trial. All subjects were abstinent from smoking overnight prior to each session, and the number of sessions was determined by the participant's success in discrimination behavior on >80 % of trials. Subjective perceptions and behavioral choice between cigarettes were also assessed and related to discrimination behavior. The median threshold was 11 mg/g, but the range was 2.4 to 16 mg/g, suggesting wide variability in discrimination threshold. Compared to the ultralow, puff choice was greater for the subject's threshold dose but only marginal for the subthreshold (next lowest nicotine) cigarette. Threshold and subthreshold also differed on subjective perceptions but not withdrawal relief. Under these testing conditions, threshold content for discriminating nicotine via cigarettes may be 11 mg/g or greater for most smokers, but some can discriminate nicotine contents one-half or one-quarter this amount. Further study with other procedures and cigarette exposure amounts may identify systematic differences in nicotine discrimination thresholds.

Reduced chromatic discrimination in children with autism spectrum disorders.

PubMed

Franklin, Anna; Sowden, Paul; Notman, Leslie; Gonzalez-Dixon, Melissa; West, Dorotea; Alexander, Iona; Loveday, Stephen; White, Alex

2010-01-01

Atypical perception in Autism Spectrum Disorders (ASD) is well documented (Dakin & Frith, 2005). However, relatively little is known about colour perception in ASD. Less accurate performance on certain colour tasks has led some to argue that chromatic discrimination is reduced in ASD relative to typical development (Franklin, Sowden, Burley, Notman & Alder, 2008). The current investigation assessed chromatic discrimination in children with high-functioning autism (HFA) and typically developing (TD) children matched on age and non-verbal cognitive ability, using the Farnsworth-Munsell 100 hue test (Experiment 1) and a threshold discrimination task (Experiment 2). In Experiment 1, more errors on the chromatic discrimination task were made by the HFA than the TD group. Comparison with test norms revealed that performance for the HFA group was at a similar level to typically developing children around 3 years younger. In Experiment 2, chromatic thresholds were elevated for the HFA group relative to the TD group. For both experiments, reduced chromatic discrimination in ASD was due to a general reduction in chromatic sensitivity rather than a specific difficulty with either red-green or blue-yellow subsystems of colour vision. The absence of group differences on control tasks ruled out an explanation in terms of general task ability rather than chromatic sensitivity. Theories to account for the reduction in chromatic discrimination in HFA are discussed, and findings are related to cortical models of perceptual processing in ASD.

Is Sweet Taste Perception Associated with Sweet Food Liking and Intake?

PubMed Central

Jayasinghe, Shakeela N.; Kruger, Rozanne; Walsh, Daniel C. I.; Cao, Guojiao; Rivers, Stacey; Richter, Marilize; Breier, Bernhard H.

2017-01-01

A range of psychophysical taste measurements are used to characterize an individual’s sweet taste perception and to assess links between taste perception and dietary intake. The aims of this study were to investigate the relationship between four different psychophysical measurements of sweet taste perception, and to explore which measures of sweet taste perception relate to sweet food intake. Forty-four women aged 20–40 years were recruited for the study. Four measures of sweet taste perception (detection and recognition thresholds, and sweet taste intensity and hedonic liking of suprathreshold concentrations) were assessed using glucose as the tastant. Dietary measurements included a four-day weighed food record, a sweet food-food frequency questionnaire and a sweet beverage liking questionnaire. Glucose detection and recognition thresholds showed no correlation with suprathreshold taste measurements or any dietary intake measurement. Importantly, sweet taste intensity correlated negatively with total energy and carbohydrate (starch, total sugar, fructose, glucose) intakes, frequency of sweet food intake and sweet beverage liking. Furthermore, sweet hedonic liking correlated positively with total energy and carbohydrate (total sugar, fructose, glucose) intakes. The present study shows a clear link between sweet taste intensity and hedonic liking with sweet food liking, and total energy, carbohydrate and sugar intake. PMID:28708085

Prestimulus Network Integration of Auditory Cortex Predisposes Near-Threshold Perception Independently of Local Excitability

PubMed Central

Leske, Sabine; Ruhnau, Philipp; Frey, Julia; Lithari, Chrysa; Müller, Nadia; Hartmann, Thomas; Weisz, Nathan

2015-01-01

An ever-increasing number of studies are pointing to the importance of network properties of the brain for understanding behavior such as conscious perception. However, with regards to the influence of prestimulus brain states on perception, this network perspective has rarely been taken. Our recent framework predicts that brain regions crucial for a conscious percept are coupled prior to stimulus arrival, forming pre-established pathways of information flow and influencing perceptual awareness. Using magnetoencephalography (MEG) and graph theoretical measures, we investigated auditory conscious perception in a near-threshold (NT) task and found strong support for this framework. Relevant auditory regions showed an increased prestimulus interhemispheric connectivity. The left auditory cortex was characterized by a hub-like behavior and an enhanced integration into the brain functional network prior to perceptual awareness. Right auditory regions were decoupled from non-auditory regions, presumably forming an integrated information processing unit with the left auditory cortex. In addition, we show for the first time for the auditory modality that local excitability, measured by decreased alpha power in the auditory cortex, increases prior to conscious percepts. Importantly, we were able to show that connectivity states seem to be largely independent from local excitability states in the context of a NT paradigm. PMID:26408799

Graph theoretical analysis of EEG functional connectivity during music perception.

PubMed

Wu, Junjie; Zhang, Junsong; Liu, Chu; Liu, Dongwei; Ding, Xiaojun; Zhou, Changle

2012-11-05

The present study evaluated the effect of music on large-scale structure of functional brain networks using graph theoretical concepts. While most studies on music perception used Western music as an acoustic stimulus, Guqin music, representative of Eastern music, was selected for this experiment to increase our knowledge of music perception. Electroencephalography (EEG) was recorded from non-musician volunteers in three conditions: Guqin music, noise and silence backgrounds. Phase coherence was calculated in the alpha band and between all pairs of EEG channels to construct correlation matrices. Each resulting matrix was converted into a weighted graph using a threshold, and two network measures: the clustering coefficient and characteristic path length were calculated. Music perception was found to display a higher level mean phase coherence. Over the whole range of thresholds, the clustering coefficient was larger while listening to music, whereas the path length was smaller. Networks in music background still had a shorter characteristic path length even after the correction for differences in mean synchronization level among background conditions. This topological change indicated a more optimal structure under music perception. Thus, prominent small-world properties are confirmed in functional brain networks. Furthermore, music perception shows an increase of functional connectivity and an enhancement of small-world network organizations. Copyright © 2012 Elsevier B.V. All rights reserved.

Problematic Internet Use: Perceptions of Addiction Counsellors

ERIC Educational Resources Information Center

Acier, Didier; Kern, Laurence

2011-01-01

Despite a growing number of publications on problematic Internet use (PIU), there is no consensus on the nature of the phenomenon, its constituent criteria, and its clinical threshold. This qualitative study examines the perceptions of addiction counsellors who have managed individuals with PIU in Quebec (Canada). Four focus groups were conducted…

Quantitative Sensory Testing in Adults with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Fründt, Odette; Grashorn, Wiebke; Schöttle, Daniel; Peiker, Ina; David, Nicole; Engel, Andreas K.; Forkmann, Katarina; Wrobel, Nathalie; Münchau, Alexander; Bingel, Ulrike

2017-01-01

Altered sensory perception has been found in patients with autism spectrum disorders (ASD) and might be related to aberrant sensory perception thresholds. We used the well-established, standardized Quantitative sensory testing (QST) protocol of the German Research Network on Neuropathic Pain to investigate 13 somatosensory parameters including…

Interactions and thresholds of limonin and nomilin in bitterness perception in orange juice and other matrices

USDA-ARS?s Scientific Manuscript database

Limonin and nomilin are two bitter compounds present in citrus and are thought to cause the bitter off-flavor of Huanglongbing-infected fruit/juice. This study determined the thresholds of limonin, nomilin, and their combination in a simple matrix (sucrose and citric acid), a complex matrix (sucrose...

Reimplantation with a conventional length electrode following residual hearing loss in four hybrid implant recipients

PubMed Central

Carlson, Matthew L; Archibald, David J; Gifford, Rene H; Driscoll, Colin LW; Beatty, Charles W

2014-01-01

Hypothesis Revision surgery using a newer-generation conventional length cochlear implant electrode will provide improved speech perception in patients that initially underwent hybrid electrode implantation and experienced post-operative loss of residual hearing and performance deterioration. Clinical presentation We present four patients who experienced delayed post-operative hearing loss following implantation with the Nucleus Hybrid S8 device and underwent reimplantation with the Nucleus Freedom or Nucleus 5 device using the Contour Advance array. Pure-tone thresholds and speech perception data were retrospectively reviewed. Intervention Four subjects underwent reimplantation with the Nucleus Freedom or Nucleus 5 device after experiencing deteriorating performance related to delayed acoustic hearing loss. Comparison of pre-revision performance to the most recent post-revision performance demonstrated improved speech perception performance in all subjects following reimplantation. Conclusions A small percent of patients will experience a significant loss of residual low-frequency hearing following hybrid implantation thereby becoming completely reliant on a shorter electrode for electrical stimulation. In the current series, reimplantation with a conventional length electrode provided improved speech perception performance in such patients. Revision surgery with a conventional length electrode should be considered in ‘short electrode’ recipients who experience performance deterioration following loss of residual hearing. PMID:22333755

Compensatory shifts in visual perception are associated with hallucinations in Lewy body disorders.

PubMed

Bowman, Alan Robert; Bruce, Vicki; Colbourn, Christopher J; Collerton, Daniel

2017-01-01

Visual hallucinations are a common, distressing, and disabling symptom of Lewy body and other diseases. Current models suggest that interactions in internal cognitive processes generate hallucinations. However, these neglect external factors. Pareidolic illusions are an experimental analogue of hallucinations. They are easily induced in Lewy body disease, have similar content to spontaneous hallucinations, and respond to cholinesterase inhibitors in the same way. We used a primed pareidolia task with hallucinating participants with Lewy body disorders (n = 16), non-hallucinating participants with Lewy body disorders (n = 19), and healthy controls (n = 20). Participants were presented with visual "noise" that sometimes contained degraded visual objects and were required to indicate what they saw. Some perceptions were cued in advance by a visual prime. Results showed that hallucinating participants were impaired in discerning visual signals from noise, with a relaxed criterion threshold for perception compared to both other groups. After the presentation of a visual prime, the criterion was comparable to the other groups. The results suggest that participants with hallucinations compensate for perceptual deficits by relaxing perceptual criteria, at a cost of seeing things that are not there, and that visual cues regularize perception. This latter finding may provide a mechanism for understanding the interaction between environments and hallucinations.

A temporal dissociation of subliminal versus supraliminal fear perception: an event-related potential study.

PubMed

Liddell, Belinda J; Williams, Leanne M; Rathjen, Jennifer; Shevrin, Howard; Gordon, Evian

2004-04-01

Current theories of emotion suggest that threat-related stimuli are first processed via an automatically engaged neural mechanism, which occurs outside conscious awareness. This mechanism operates in conjunction with a slower and more comprehensive process that allows a detailed evaluation of the potentially harmful stimulus (LeDoux, 1998). We drew on the Halgren and Marinkovic (1995) model to examine these processes using event-related potentials (ERPs) within a backward masking paradigm. Stimuli used were faces with fear and neutral (as baseline control) expressions, presented above (supraliminal) and below (subliminal) the threshold for conscious detection. ERP data revealed a double dissociation for the supraliminal versus subliminal perception of fear. In the subliminal condition, responses to the perception of fear stimuli were enhanced relative to neutral for the N2 "excitatory" component, which is thought to represent orienting and automatic aspects of face processing. By contrast, supraliminal perception of fear was associated with relatively enhanced responses for the late P3 "inhibitory" component, implicated in the integration of emotional processes. These findings provide evidence in support of Halgren and Marinkovic's temporal model of emotion processing, and indicate that the neural mechanisms for appraising signals of threat may be initiated, not only automatically, but also without the need for conscious detection of these signals.

Odour perception in chronic renal disease.

PubMed

Griep, M I; Van der Niepen, P; Sennesael, J J; Mets, T F; Massart, D L; Verbeelen, D L

1997-10-01

The sense of smell plays an important role in the quality of life. Many studies have shown a declining odour perception in the elderly, as well as in subjects in poor health or nutritional state. Considering the high prevalence of poor nutritional state in renal disease and the importance of odour perception in nutrition and health, the relationship between renal function, nutritional state, and odour perception is explored in this study. A total of 101 patients with chronic renal failure participated in the study. Thirty-eight haemodialysis patients (mean age = 64.3 years) were evaluated both before and after dialysis. Sixteen patients on peritoneal dialysis treatment (mean age = 64.0 years), 28 transplanted patients (mean age = 53.5 years, mean creatinine clearance = 64.0 ml/min) and 19 patients with varying degrees of renal insufficiency were also included (mean age = 63.7 years, mean creatinine clearance = 29.5 ml/min). Patients with cognitive deficits or upper respiratory airway diseases were excluded. A validated objective procedure was used to measure odour perception, by determining the detection threshold for isoamyl acetate (banana odour) as the lowest detectable odour concentration. Healthy control persons had significantly lower odour thresholds compared to patients on peritoneal (P = 0.001) and haemodialysis (P = 0.002). No significant difference was observed in odour perception between patients on peritoneal and haemodialysis (P = 0.779) and for patients on haemodialysis before and after a dialysis session. Transplanted patients had significantly better odour perception compared to matched patients on dialysis (P < 0.001). Odour perception of transplanted patients and matched healthy control persons was similar (P = 0.81). In patients with varying degrees of renal insufficiency, including healthy controls and transplanted patients, a significant positive correlation was found between odour perception and creatinine clearance (P = 0.02). A significant negative correlation was found between odour perception and serum concentration of urea (P < 0.001), serum phosphorus (P = 0.022) and protein catabolic rate (P < 0.05). Other parameters measuring nutritional status (albumin, BMI) were not correlated with odour perception. Our results show that the ability to smell is severely impaired in patients with chronic renal failure and is related to the degree of renal impairment and the degree of accumulation of uraemic toxins. After renal transplantation, patients have a normal odour perception, indicating the capacity of the olfactory system to recover once the concentration of uraemic toxins remains below a critical threshold. Acute removal of uraemic toxins by dialysis does not correct olfactory disturbances, suggesting a long lasting effect of uraemia on olfactory function.

Using Electrically-evoked Compound Action Potentials to Estimate Perceptive Levels in Experienced Adult Cochlear Implant Users.

PubMed

Joly, Charles-Alexandre; Péan, Vincent; Hermann, Ruben; Seldran, Fabien; Thai-Van, Hung; Truy, Eric

2017-10-01

The cochlear implant (CI) fitting level prediction accuracy of electrically-evoked compound action potential (ECAP) should be enhanced by the addition of demographic data in models. No accurate automated fitting of CI based on ECAP has yet been proposed. We recorded ECAP in 45 adults who had been using MED-EL CIs for more than 11 months and collected the most comfortable loudness level (MCL) used for CI fitting (prog-MCL), perception thresholds (meas-THR), and MCL (meas-MCL) measured with the stimulation used for ECAP recording. Linear mixed models taking into account cochlear site factors were computed to explain prog-MCL, meas-MCL, and meas-THR. Cochlear region and ECAP threshold were predictors of the three levels. In addition, significant predictors were the ECAP amplitude for the prog-MCL and the duration of deafness for the prog-MCL and the meas-THR. Estimations were more accurate for the meas-THR, then the meas-MCL, and finally the prog-MCL. These results show that 1) ECAP thresholds are more closely related to perception threshold than to comfort level, 2) predictions are more accurate when the inter-subject and cochlear regions variations are considered, and 3) differences between the stimulations used for ECAP recording and for CI fitting make it difficult to accurately predict the prog-MCL from the ECAP recording. Predicted prog-MCL could be used as bases for fitting but should be used with care to avoid any uncomfortable or painful stimulation.

Perception of Self-Motion and Regulation of Walking Speed in Young-Old Adults.

PubMed

Lalonde-Parsi, Marie-Jasmine; Lamontagne, Anouk

2015-07-01

Whether a reduced perception of self-motion contributes to poor walking speed adaptations in older adults is unknown. In this study, speed discrimination thresholds (perceptual task) and walking speed adaptations (walking task) were compared between young (19-27 years) and young-old individuals (63-74 years), and the relationship between the performance on the two tasks was examined. Participants were evaluated while viewing a virtual corridor in a helmet-mounted display. Speed discrimination thresholds were determined using a staircase procedure. Walking speed modulation was assessed on a self-paced treadmill while exposed to different self-motion speeds ranging from 0.25 to 2 times the participants' comfortable speed. For each speed, participants were instructed to match the self-motion speed described by the moving corridor. On the walking task, participants displayed smaller walking speed errors at comfortable walking speeds compared with slower of faster speeds. The young-old adults presented larger speed discrimination thresholds (perceptual experiment) and larger walking speed errors (walking experiment) compared with young adults. Larger walking speed errors were associated with higher discrimination thresholds. The enhanced performance on the walking task at comfortable speed suggests that intersensory calibration processes are influenced by experience, hence optimized for frequently encountered conditions. The altered performance of the young-old adults on the perceptual and walking tasks, as well as the relationship observed between the two tasks, suggest that a poor perception of visual motion information may contribute to the poor walking speed adaptations that arise with aging.

Comparing spatial tuning curves, spectral ripple resolution, and speech perception in cochlear implant users.

PubMed

Anderson, Elizabeth S; Nelson, David A; Kreft, Heather; Nelson, Peggy B; Oxenham, Andrew J

2011-07-01

Spectral ripple discrimination thresholds were measured in 15 cochlear-implant users with broadband (350-5600 Hz) and octave-band noise stimuli. The results were compared with spatial tuning curve (STC) bandwidths previously obtained from the same subjects. Spatial tuning curve bandwidths did not correlate significantly with broadband spectral ripple discrimination thresholds but did correlate significantly with ripple discrimination thresholds when the rippled noise was confined to an octave-wide passband, centered on the STC's probe electrode frequency allocation. Ripple discrimination thresholds were also measured for octave-band stimuli in four contiguous octaves, with center frequencies from 500 Hz to 4000 Hz. Substantial variations in thresholds with center frequency were found in individuals, but no general trends of increasing or decreasing resolution from apex to base were observed in the pooled data. Neither ripple nor STC measures correlated consistently with speech measures in noise and quiet in the sample of subjects in this study. Overall, the results suggest that spectral ripple discrimination measures provide a reasonable measure of spectral resolution that correlates well with more direct, but more time-consuming, measures of spectral resolution, but that such measures do not always provide a clear and robust predictor of performance in speech perception tasks. © 2011 Acoustical Society of America

Comparing spatial tuning curves, spectral ripple resolution, and speech perception in cochlear implant users

PubMed Central

Anderson, Elizabeth S.; Nelson, David A.; Kreft, Heather; Nelson, Peggy B.; Oxenham, Andrew J.

2011-01-01

Spectral ripple discrimination thresholds were measured in 15 cochlear-implant users with broadband (350–5600 Hz) and octave-band noise stimuli. The results were compared with spatial tuning curve (STC) bandwidths previously obtained from the same subjects. Spatial tuning curve bandwidths did not correlate significantly with broadband spectral ripple discrimination thresholds but did correlate significantly with ripple discrimination thresholds when the rippled noise was confined to an octave-wide passband, centered on the STC’s probe electrode frequency allocation. Ripple discrimination thresholds were also measured for octave-band stimuli in four contiguous octaves, with center frequencies from 500 Hz to 4000 Hz. Substantial variations in thresholds with center frequency were found in individuals, but no general trends of increasing or decreasing resolution from apex to base were observed in the pooled data. Neither ripple nor STC measures correlated consistently with speech measures in noise and quiet in the sample of subjects in this study. Overall, the results suggest that spectral ripple discrimination measures provide a reasonable measure of spectral resolution that correlates well with more direct, but more time-consuming, measures of spectral resolution, but that such measures do not always provide a clear and robust predictor of performance in speech perception tasks. PMID:21786905

The Influence of Pregnancy on Sweet Taste Perception and Plaque Acidogenicity.

PubMed

Sonbul, H; Ashi, H; Aljahdali, E; Campus, G; Lingström, P

2017-05-01

Objectives Women undergo different physiological and oral changes during pregnancy and this may increase the risk of dental caries and other oral diseases. The aim of the present study was to investigate changes in biofilm acidogenicity and correlate them to sweet taste perception in pregnant and non-pregnant women. Methods Three groups of Saudi women participated in this cross-sectional study: (1) women in early pregnancy (n = 40/mean age 29.6 years/DMFT 10.7), (2) women in late pregnancy (n = 40/29.5 years/DMFT 10.8) and (3) non-pregnant women (n = 41/27.7 years/DMFT 12.3). Changes in plaque pH were determined by using colour-coded indicator strips before and after a 1-min rinse with a 10% sucrose solution. A taste perception test determining sweet preference and threshold levels was also performed. Results A significant difference regarding plaque pH was seen between the early, late and non-pregnant women when calculated as the area under the curve (p < 0.05). Regarding the taste perception tests, taste preference and threshold were correlated (p < 0.001, r = 0.6). Between the three groups, a statistically significant difference was seen in taste threshold and taste preference respectively (p = 0.001 and p < 0.001). Conclusions The findings in this study suggest that pregnant women may undergo taste changes and experience lower plaque pH, which may result in an increased risk of dental caries.

Perception of combined translation and rotation in the horizontal plane in humans

PubMed Central

2016-01-01

Thresholds and biases of human motion perception were determined for yaw rotation and sway (left-right) and surge (fore-aft) translation, independently and in combination. Stimuli were 1 Hz sinusoid in acceleration with a peak velocity of 14°/s or cm/s. Test stimuli were adjusted based on prior responses, whereas the distracting stimulus was constant. Seventeen human subjects between the ages of 20 and 83 completed the experiments and were divided into 2 groups: younger and older than 50. Both sway and surge translation thresholds significantly increased when combined with yaw rotation. Rotation thresholds were not significantly increased by the presence of translation. The presence of a yaw distractor significantly biased perception of sway translation, such that during 14°/s leftward rotation, the point of subjective equality (PSE) occurred with sway of 3.2 ± 0.7 (mean ± SE) cm/s to the right. Likewise, during 14°/s rightward motion, the PSE was with sway of 2.9 ± 0.7 cm/s to the left. A sway distractor did not bias rotation perception. When subjects were asked to report the direction of translation while varying the axis of yaw rotation, the PSE at which translation was equally likely to be perceived in either direction was 29 ± 11 cm anterior to the midline. These results demonstrated that rotation biased translation perception, such that it is minimized when rotating about an axis anterior to the head. Since the combination of translation and rotation during ambulation is consistent with an axis anterior to the head, this may reflect a mechanism by which movements outside the pattern that occurs during ambulation are perceived. PMID:27334952

Tactile Sensitivity of Children: Effects of Frequency, Masking, and the Non-Pacinian I Psychophysical Channel

ERIC Educational Resources Information Center

Guclu, Burak; Oztek, Cigdem

2007-01-01

Tactile perception depends on the contributions of four psychophysical tactile channels mediated by four corresponding receptor systems. The sensitivity of the tactile channels is determined by detection thresholds that vary as a function of the stimulus frequency. It has been widely reported that tactile thresholds increase (i.e., sensitivity…

Auditory Stream Segregation and the Perception of Across-Frequency Synchrony

ERIC Educational Resources Information Center

Micheyl, Christophe; Hunter, Cynthia; Oxenham, Andrew J.

2010-01-01

This study explored the extent to which sequential auditory grouping affects the perception of temporal synchrony. In Experiment 1, listeners discriminated between 2 pairs of asynchronous "target" tones at different frequencies, A and B, in which the B tone either led or lagged. Thresholds were markedly higher when the target tones were temporally…

Seeing and identifying with a virtual body decreases pain perception.

PubMed

Hänsel, Alexander; Lenggenhager, Bigna; von Känel, Roland; Curatolo, Michele; Blanke, Olaf

2011-09-01

Pain and the conscious mind (or the self) are experienced in our body. Both are intimately linked to the subjective quality of conscious experience. Here, we used virtual reality technology and visuo-tactile conflicts in healthy subjects to test whether experimentally induced changes of bodily self-consciousness (self-location; self-identification) lead to changes in pain perception. We found that visuo-tactile stroking of a virtual body but not of a control object led to increased pressure pain thresholds and self-location. This increase was not modulated by the synchrony of stroking as predicted based on earlier work. This differed for self-identification where we found as predicted that synchrony of stroking increased self-identification with the virtual body (but not a control object), and positively correlated with an increase in pain thresholds. We discuss the functional mechanisms of self-identification, self-location, and the visual perception of human bodies with respect to pain perception. Copyright © 2011 European Federation of International Association for the Study of Pain Chapters. Published by Elsevier Ltd. All rights reserved.

Threshold dose for behavioral discrimination of cigarette nicotine content in menthol vs. non-menthol smokers.

PubMed

Perkins, Kenneth A; Kunkle, Nicole; Karelitz, Joshua L

2017-04-01

The lowest threshold content (or "dose") of nicotine discriminated in cigarettes may differ due to menthol preference. Menthol and non-menthol Spectrum research cigarettes differing in nicotine content were used to determine discrimination thresholds. Dependent smokers preferring menthol (n = 40) or non-menthol (n = 21) brands were tested on ability to discriminate cigarettes (matched for their menthol preference) with nicotine contents of 16-17, 11-12, 5, 2, and 1 mg/g, one per session, from an "ultra-low" cigarette with 0.4 mg/g. Controlled exposure to each cigarette was four puffs/trial, and the number of sessions was determined by the lowest nicotine content they could discriminate on >80% of trials (i.e., ≥5 of 6). We also assessed subjective perceptions and behavioral choice between cigarettes to relate them to discrimination responses. Controlling for Fagerstrom Test of Nicotine Dependence score, discrimination thresholds were more likely to be at higher nicotine content cigarettes for menthol vs. non-menthol smokers (p < .005), with medians of 16 vs. 11 mg/g, respectively. Compared to the ultra-low, threshold and subthreshold (next lowest) cigarettes differed on most perceptions and puff choice, but menthol preference did not alter these associations. Notably, threshold cigarettes did, but subthreshold did not, increase choice over the ultra-low. Threshold for discriminating nicotine via smoking may be generally higher for menthol vs. non-menthol smokers. More research is needed to identify why menthol smoking is related to higher nicotine thresholds and to verify that cigarettes unable to be discriminated do not support reinforcement.

Aided and Unaided Speech Perception by Older Hearing Impaired Listeners

PubMed Central

Woods, David L.; Arbogast, Tanya; Doss, Zoe; Younus, Masood; Herron, Timothy J.; Yund, E. William

2015-01-01

The most common complaint of older hearing impaired (OHI) listeners is difficulty understanding speech in the presence of noise. However, tests of consonant-identification and sentence reception threshold (SeRT) provide different perspectives on the magnitude of impairment. Here we quantified speech perception difficulties in 24 OHI listeners in unaided and aided conditions by analyzing (1) consonant-identification thresholds and consonant confusions for 20 onset and 20 coda consonants in consonant-vowel-consonant (CVC) syllables presented at consonant-specific signal-to-noise (SNR) levels, and (2) SeRTs obtained with the Quick Speech in Noise Test (QSIN) and the Hearing in Noise Test (HINT). Compared to older normal hearing (ONH) listeners, nearly all unaided OHI listeners showed abnormal consonant-identification thresholds, abnormal consonant confusions, and reduced psychometric function slopes. Average elevations in consonant-identification thresholds exceeded 35 dB, correlated strongly with impairments in mid-frequency hearing, and were greater for hard-to-identify consonants. Advanced digital hearing aids (HAs) improved average consonant-identification thresholds by more than 17 dB, with significant HA benefit seen in 83% of OHI listeners. HAs partially normalized consonant-identification thresholds, reduced abnormal consonant confusions, and increased the slope of psychometric functions. Unaided OHI listeners showed much smaller elevations in SeRTs (mean 6.9 dB) than in consonant-identification thresholds and SeRTs in unaided listening conditions correlated strongly (r = 0.91) with identification thresholds of easily identified consonants. HAs produced minimal SeRT benefit (2.0 dB), with only 38% of OHI listeners showing significant improvement. HA benefit on SeRTs was accurately predicted (r = 0.86) by HA benefit on easily identified consonants. Consonant-identification tests can accurately predict sentence processing deficits and HA benefit in OHI listeners. PMID:25730423

Ethnic differences in thermal pain responses: a comparison of South Asian and White British healthy males.

PubMed

Watson, Paul J; Latif, R Khalid; Rowbotham, David J

2005-11-01

The expression and report of pain is influenced by social environment and culture. Previous studies have suggested ethnically determined differences in report of pain threshold, intensity and affect. The influence of ethnic differences between White British and South Asians has remained unexplored. Twenty age-matched, male volunteers in each group underwent evaluation. Cold and warm perception and cold and heat threshold were assessed using an ascending method of limits. Magnitude estimation of pain unpleasantness and pain intensity were investigated with thermal stimuli of 46, 47, 48 and 49 degrees C. Subjects also completed a pain anxiety questionnaire. Data was analysed using t-test, Mann-Whitney and repeated measures analysis of variance as appropriate. There were no differences in cold and warm perception between the two groups. There was a statistically significant difference between the two groups for heat pain threshold (P=0.006) and heat pain intensity demonstrated a significant effect for ethnicity (F=13.84, P=0.001). Although no group differences emerged for cold pain threshold and heat unpleasantness, South Asians demonstrated lower cold pain threshold and reported more unpleasantness at all temperatures but this was not statistically significant. Our study shows that ethnicity plays an important role in heat pain threshold and pain report, South Asian males demonstrated lower pain thresholds and higher pain report when compared with matched White British males. There were no differences in pain anxiety between the two groups and no correlations were identified between pain and pain anxiety Haemodynamic measures and anthropometry did not explain group differences.

Preliminary test of cigarette nicotine discrimination threshold in non-dependent versus dependent smokers.

PubMed

Perkins, Kenneth A; Kunkle, Nicole; Karelitz, Joshua L; Perkins, K A; Kunkle, N; Karelitz, J L

2017-06-01

Despite its potential for understanding tobacco dependence, behavioral discrimination of nicotine via smoking has not been formally examined as a function of nicotine dependence level. Spectrum research cigarettes were used to compare non-dependent with dependent smokers on the lowest content of nicotine they could discriminate (i.e., "threshold"). Dependent (n=21; 16M, 5F) or non-dependent (n=7; 4M, 3F) smokers were tested on ability to discriminate between cigarettes with nicotine contents of 17, 11, 5, 2, and 1mg/g, one per session, from an "ultra-low" cigarette with 0.4mg/g (all had 9-10mg "tar"). All abstained from smoking overnight prior to sessions, and number of sessions was determined by the lowest nicotine content they could reliably discriminate from the ultra-low on >80% of trials (i.e., ≥5 of 6). Subjective perceptions and cigarette choice behavior were also assessed and related to discrimination behavior. Discrimination thresholds (and most perceptions) did not differ between dependent and non-dependent smokers, with median thresholds of 11mg/g for both subgroups. Yet, "liking" and puff choice for threshold cigarettes were greater in dependent but not non-dependent smokers, while cigarettes with nicotine contents below threshold did not support "liking" or choice in both groups. In sum, this preliminary study suggests threshold for discriminating nicotine via smoking may not vary by dependence level, and further study is needed to confirm that cigarettes unable to be discriminated are also not reinforcing. Copyright © 2017 Elsevier B.V. All rights reserved.

[Decrease and asymmetry in taste perception in patients with nerve trunk damage].

PubMed

Nikulina, V A; Kokin, G S; Morozov, I S

1995-01-01

The purpose of this article was the gustatory perception state study (NaCl solution perception) in patients with one-sided damages of branchial plexus as well as of radial, facial and ulnar nervous trunks. The decrease of gustatory perception was observed in 78 (70.3%) cases, while the lack of such alterations in 33 (29.7%) patients. The gustatory perception disturbances (increase of the absolute threshold on the ipsilateral tongue's half) took place in 82.2% and 69.6% at right and left limbs damages respectively. The results presented testified the strengthening of normally existing asymmetry in gustatory perception especially in patients with left-sided denervation. The degree of gustatory perception restoration may serve as a prognostic test at surgery of such patients.

The Triple-Flash Illusion Reveals a Driving Role of Alpha-Band Reverberations in Visual Perception.

PubMed

Gulbinaite, Rasa; İlhan, Barkın; VanRullen, Rufin

2017-07-26

The modulatory role of spontaneous brain oscillations on perception of threshold-level stimuli is well established. Here, we provide evidence that alpha-band (∼10 Hz) oscillations not only modulate perception of threshold-level sensory inputs but also can drive perception and generate percepts without a physical stimulus being present. We used the "triple-flash" illusion: Occasional perception of three flashes when only two spatially coincident veridical ones, separated by ∼100 ms, are presented. The illusion was proposed to result from superposition of two hypothetical oscillatory impulse response functions generated in response to each flash: When the delay between flashes matches the period of the oscillation, the superposition enhances a later part of the oscillation that is normally damped; when this enhancement crosses perceptual threshold, a third flash is erroneously perceived (Bowen, 1989). In Experiment 1, we varied stimulus onset asynchrony and validated Bowen's theory: The optimal stimulus onset asynchrony for illusion to occur was correlated, across human subjects (both genders), with the subject-specific impulse response function period determined from a separate EEG experiment. Experiment 2 revealed that prestimulus parietal, but no occipital, alpha EEG phase and power, as well as poststimulus alpha phase-locking, together determine the occurrence of the illusion on a trial-by-trial basis. Thus, oscillatory reverberations create something out of nothing: A third flash where there are only two. SIGNIFICANCE STATEMENT We highlight a novel property of alpha-band (∼10 Hz) oscillations based on three experiments (two EEG and one psychophysics) by demonstrating that alpha-band oscillations do not merely modulate perception, but can also drive perception. We show that human participants report seeing a third flash when only two are presented (the "triple-flash" illusion) most often when the interflash delay matches the period of participant's oscillatory impulse response function reverberating in alpha. Within-subject, the phase and power of ongoing parietal, but not occipital, alpha-band oscillations at the time of the first flash determine illusory percept on a trial-by-trial basis. We revealed a physiologically plausible mechanism that validates and extends the original theoretical account of the triple-flash illusion proposed by Bowen in 1989. Copyright © 2017 the authors 0270-6474/17/377219-12$15.00/0.

Masked speech perception across the adult lifespan: Impact of age and hearing impairment.

PubMed

Goossens, Tine; Vercammen, Charlotte; Wouters, Jan; van Wieringen, Astrid

2017-02-01

As people grow older, speech perception difficulties become highly prevalent, especially in noisy listening situations. Moreover, it is assumed that speech intelligibility is more affected in the event of background noises that induce a higher cognitive load, i.e., noises that result in informational versus energetic masking. There is ample evidence showing that speech perception problems in aging persons are partly due to hearing impairment and partly due to age-related declines in cognition and suprathreshold auditory processing. In order to develop effective rehabilitation strategies, it is indispensable to know how these different degrading factors act upon speech perception. This implies disentangling effects of hearing impairment versus age and examining the interplay between both factors in different background noises of everyday settings. To that end, we investigated open-set sentence identification in six participant groups: a young (20-30 years), middle-aged (50-60 years), and older cohort (70-80 years), each including persons who had normal audiometric thresholds up to at least 4 kHz, on the one hand, and persons who were diagnosed with elevated audiometric thresholds, on the other hand. All participants were screened for (mild) cognitive impairment. We applied stationary and amplitude modulated speech-weighted noise, which are two types of energetic maskers, and unintelligible speech, which causes informational masking in addition to energetic masking. By means of these different background noises, we could look into speech perception performance in listening situations with a low and high cognitive load, respectively. Our results indicate that, even when audiometric thresholds are within normal limits up to 4 kHz, irrespective of threshold elevations at higher frequencies, and there is no indication of even mild cognitive impairment, masked speech perception declines by middle age and decreases further on to older age. The impact of hearing impairment is as detrimental for young and middle-aged as it is for older adults. When the background noise becomes cognitively more demanding, there is a larger decline in speech perception, due to age or hearing impairment. Hearing impairment seems to be the main factor underlying speech perception problems in background noises that cause energetic masking. However, in the event of informational masking, which induces a higher cognitive load, age appears to explain a significant part of the communicative impairment as well. We suggest that the degrading effect of age is mediated by deficiencies in temporal processing and central executive functions. This study may contribute to the improvement of auditory rehabilitation programs aiming to prevent aging persons from missing out on conversations, which, in turn, will improve their quality of life. Copyright © 2016 Elsevier B.V. All rights reserved.

Saturation in Phosphene Size with Increasing Current Levels Delivered to Human Visual Cortex.

PubMed

Bosking, William H; Sun, Ping; Ozker, Muge; Pei, Xiaomei; Foster, Brett L; Beauchamp, Michael S; Yoshor, Daniel

2017-07-26

Electrically stimulating early visual cortex results in a visual percept known as a phosphene. Although phosphenes can be evoked by a wide range of electrode sizes and current amplitudes, they are invariably described as small. To better understand this observation, we electrically stimulated 93 electrodes implanted in the visual cortex of 13 human subjects who reported phosphene size while stimulation current was varied. Phosphene size increased as the stimulation current was initially raised above threshold, but then rapidly reached saturation. Phosphene size also depended on the location of the stimulated site, with size increasing with distance from the foveal representation. We developed a model relating phosphene size to the amount of activated cortex and its location within the retinotopic map. First, a sigmoidal curve was used to predict the amount of activated cortex at a given current. Second, the amount of active cortex was converted to degrees of visual angle by multiplying by the inverse cortical magnification factor for that retinotopic location. This simple model accurately predicted phosphene size for a broad range of stimulation currents and cortical locations. The unexpected saturation in phosphene sizes suggests that the functional architecture of cerebral cortex may impose fundamental restrictions on the spread of artificially evoked activity and this may be an important consideration in the design of cortical prosthetic devices. SIGNIFICANCE STATEMENT Understanding the neural basis for phosphenes, the visual percepts created by electrical stimulation of visual cortex, is fundamental to the development of a visual cortical prosthetic. Our experiments in human subjects implanted with electrodes over visual cortex show that it is the activity of a large population of cells spread out across several millimeters of tissue that supports the perception of a phosphene. In addition, we describe an important feature of the production of phosphenes by electrical stimulation: phosphene size saturates at a relatively low current level. This finding implies that, with current methods, visual prosthetics will have a limited dynamic range available to control the production of spatial forms and that more advanced stimulation methods may be required. Copyright © 2017 the authors 0270-6474/17/377188-10$15.00/0.

An Intrinsic Role of Beta Oscillations in Memory for Time Estimation.

PubMed

Wiener, Martin; Parikh, Alomi; Krakow, Arielle; Coslett, H Branch

2018-05-22

The neural mechanisms underlying time perception are of vital importance to a comprehensive understanding of behavior and cognition. Recent work has suggested a supramodal role for beta oscillations in measuring temporal intervals. However, the precise function of beta oscillations and whether their manipulation alters timing has yet to be determined. To accomplish this, we first re-analyzed two, separate EEG datasets and demonstrate that beta oscillations are associated with the retention and comparison of a memory standard for duration. We next conducted a study of 20 human participants using transcranial alternating current stimulation (tACS), over frontocentral cortex, at alpha and beta frequencies, during a visual temporal bisection task, finding that beta stimulation exclusively shifts the perception of time such that stimuli are reported as longer in duration. Finally, we decomposed trialwise choice data with a drift diffusion model of timing, revealing that the shift in timing is caused by a change in the starting point of accumulation, rather than the drift rate or threshold. Our results provide evidence for the intrinsic involvement of beta oscillations in the perception of time, and point to a specific role for beta oscillations in the encoding and retention of memory for temporal intervals.

A portable meter for measuring low frequency currents in the human body.

PubMed

Niple, J C; Daigle, J P; Zaffanella, L E; Sullivan, T; Kavet, R

2004-07-01

A portable meter has been developed for measuring low frequency currents that flow in the human body. Although the present version of the meter was specifically designed to measure 50/60 Hz "contact currents," the principles involved can be used with other low frequency body currents. Contact currents flow when the human body provides a conductive path between objects in the environment with different electrical potentials. The range of currents the meter detects is approximately 0.4-800 microA. This provides measurements of currents from the threshold of human perception (approximately 500 microA(RMS)) down to single microampere levels. The meter has a unique design, which utilizes the human subject's body impedance as the sensing element. Some of the advantages of this approach are high sensitivity, the ability to measure current flow in the majority of the body, and relative insensitivity to the current path connection points. Current measurement accuracy varies with the accuracy of the body impedance (resistance) measurement and different techniques can be used to obtain a desired level of accuracy. Techniques are available to achieve an estimated +/-20% accuracy. Copyright 2004 Wiley-Liss, Inc.

Fluctuation scaling in the visual cortex at threshold

NASA Astrophysics Data System (ADS)

Medina, José M.; Díaz, José A.

2016-05-01

Fluctuation scaling relates trial-to-trial variability to the average response by a power function in many physical processes. Here we address whether fluctuation scaling holds in sensory psychophysics and its functional role in visual processing. We report experimental evidence of fluctuation scaling in human color vision and form perception at threshold. Subjects detected thresholds in a psychophysical masking experiment that is considered a standard reference for studying suppression between neurons in the visual cortex. For all subjects, the analysis of threshold variability that results from the masking task indicates that fluctuation scaling is a global property that modulates detection thresholds with a scaling exponent that departs from 2, β =2.48 ±0.07 . We also examine a generalized version of fluctuation scaling between the sample kurtosis K and the sample skewness S of threshold distributions. We find that K and S are related and follow a unique quadratic form K =(1.19 ±0.04 ) S2+(2.68 ±0.06 ) that departs from the expected 4/3 power function regime. A random multiplicative process with weak additive noise is proposed based on a Langevin-type equation. The multiplicative process provides a unifying description of fluctuation scaling and the quadratic S -K relation and is related to on-off intermittency in sensory perception. Our findings provide an insight into how the human visual system interacts with the external environment. The theoretical methods open perspectives for investigating fluctuation scaling and intermittency effects in a wide variety of natural, economic, and cognitive phenomena.

A simulation framework for auditory discrimination experiments: Revealing the importance of across-frequency processing in speech perception.

PubMed

Schädler, Marc René; Warzybok, Anna; Ewert, Stephan D; Kollmeier, Birger

2016-05-01

A framework for simulating auditory discrimination experiments, based on an approach from Schädler, Warzybok, Hochmuth, and Kollmeier [(2015). Int. J. Audiol. 54, 100-107] which was originally designed to predict speech recognition thresholds, is extended to also predict psychoacoustic thresholds. The proposed framework is used to assess the suitability of different auditory-inspired feature sets for a range of auditory discrimination experiments that included psychoacoustic as well as speech recognition experiments in noise. The considered experiments were 2 kHz tone-in-broadband-noise simultaneous masking depending on the tone length, spectral masking with simultaneously presented tone signals and narrow-band noise maskers, and German Matrix sentence test reception threshold in stationary and modulated noise. The employed feature sets included spectro-temporal Gabor filter bank features, Mel-frequency cepstral coefficients, logarithmically scaled Mel-spectrograms, and the internal representation of the Perception Model from Dau, Kollmeier, and Kohlrausch [(1997). J. Acoust. Soc. Am. 102(5), 2892-2905]. The proposed framework was successfully employed to simulate all experiments with a common parameter set and obtain objective thresholds with less assumptions compared to traditional modeling approaches. Depending on the feature set, the simulated reference-free thresholds were found to agree with-and hence to predict-empirical data from the literature. Across-frequency processing was found to be crucial to accurately model the lower speech reception threshold in modulated noise conditions than in stationary noise conditions.

A pilot study of reference vibrotactile perception thresholds on the fingertip obtained with Malaysian healthy people using ISO 13091-1 equipment.

PubMed

Daud, Roshada; Maeda, Setsuo; Kameel, Nur Nazmin Mustafa; Ripin, Muhamad Yunus; Bakrun, Norazman; Md Zein, Raemy; Kido, Masaharu; Higuchi, Kiyotaka

2004-04-01

The purpose of this paper is to clarify the reference vibrotactile perception thresholds (VPT) for healthy people in Malaysia. The measurement equipment standard, ISO 13091-1, of the vibrotactile perception thresholds for the assessment of nerve dysfunction and the analysis and interpretation of measurements at the fingertips standard, ISO 13091-2, were published in ISO/TC108/SC4/WG8 on 2001 and 2003 individually. In the ISO 13091-2 standard, the reference VPT data were obtained from few research papers. Malaysian people's VPT data don't include to this standard. In Malaysia, when the VPT is using to diagnose of the hand-arm vibration syndrome, the reference VPT data need to compare with the worker's ones. But, Malaysia does not have the reference VPT data yet. So, in this paper, the VPT was measured by using ISO 13091-1 standard equipment to obtain the reference data for Malaysian people. And these data were compared with the ISO reference data on the ISO 13091-2 standard. From the comparison of these data, it was clear that the Malaysian healthy people's VPT data were consistent with the reference data of the ISO 13091-2 standard.

Computational gestalts and perception thresholds.

PubMed

Desolneux, Agnès; Moisan, Lionel; Morel, Jean-Michel

2003-01-01

In 1923, Max Wertheimer proposed a research programme and method in visual perception. He conjectured the existence of a small set of geometric grouping laws governing the perceptual synthesis of phenomenal objects, or "gestalt" from the atomic retina input. In this paper, we review this set of geometric grouping laws, using the works of Metzger, Kanizsa and their schools. In continuation, we explain why the Gestalt theory research programme can be translated into a Computer Vision programme. This translation is not straightforward, since Gestalt theory never addressed two fundamental matters: image sampling and image information measurements. Using these advances, we shall show that gestalt grouping laws can be translated into quantitative laws allowing the automatic computation of gestalts in digital images. From the psychophysical viewpoint, a main issue is raised: the computer vision gestalt detection methods deliver predictable perception thresholds. Thus, we are set in a position where we can build artificial images and check whether some kind of agreement can be found between the computationally predicted thresholds and the psychophysical ones. We describe and discuss two preliminary sets of experiments, where we compared the gestalt detection performance of several subjects with the predictable detection curve. In our opinion, the results of this experimental comparison support the idea of a much more systematic interaction between computational predictions in Computer Vision and psychophysical experiments.

Stochastic Resonance In Visual Perception

NASA Astrophysics Data System (ADS)

Simonotto, Enrico

1996-03-01

Stochastic resonance (SR) is a well established physical phenomenon wherein some measure of the coherence of a weak signal can be optimized by random fluctuations, or "noise" (K. Wiesenfeld and F. Moss, Nature), 373, 33 (1995). In all experiments to date the coherence has been measured using numerical analysis of the data, for example, signal-to-noise ratios obtained from power spectra. But, can this analysis be replaced by a perceptive task? Previously we had demonstrated this possibility with a numerical model of perceptual bistability applied to the interpretation of ambiguous figures(M. Riani and E. Simonotto, Phys. Rev. Lett.), 72, 3120 (1994). Here I describe an experiment wherein SR is detected in visual perception. A recognizible grayscale photograph was digitized and presented. The picture was then placed beneath a threshold. Every pixel for which the grayscale exceeded the threshold was painted white, and all others black. For large enough threshold, the picture is unrecognizable, but the addition of a random number to every pixel renders it interpretable(C. Seife and M. Roberts, The Economist), 336, 59, July 29 (1995). However the addition of dynamical noise to the pixels much enhances an observer's ability to interpret the picture. Here I report the results of psychophysics experiments wherein the effects of both the intensity of the noise and its correlation time were studied.

Variability of argon laser-induced sensory and pain thresholds on human oral mucosa and skin.

PubMed Central

Svensson, P.; Bjerring, P.; Arendt-Nielsen, L.; Kaaber, S.

1991-01-01

The variability of laser-induced pain perception on human oral mucosa and hairy skin was investigated in order to establish a new method for evaluation of pain in the orofacial region. A high-energy argon laser was used for experimental pain stimulation, and sensory and pain thresholds were determined. The intra-individual coefficients of variation for oral thresholds were comparable to cutaneous thresholds. However, inter-individual variation was smaller for oral thresholds, which could be due to larger variation in cutaneous optical properties. The short-term and 24-hr changes in thresholds on both surfaces were less than 9%. The results indicate that habituation to laser thresholds may account for part of the intra-individual variation observed. However, the subjective ratings of the intensity of the laser stimuli were constant. Thus, oral thresholds may, like cutaneous thresholds, be used for assessment and quantification of analgesic efficacies and to investigate various pain conditions. PMID:1814248

Connecting Medical Records: An Evaluation of Benefits and Challenges for Primary Care Practices.

PubMed

Compeau, Deborah Ruth; Terry, Amanda

2017-06-30

Implementation of systems to support health information sharing has lagged other areas of healthcare IT, yet offers a strong possibility for benefit.  Clinical acceptance is a key limiting factor in health IT adoption. To assess the benefits and challenges experienced by clinicians using a custom-developed health information exchange system, and to show how perceptions of benefits and challenges influence perceptions of productivity and care-related outcomes. We used a mixed methods design with two phases. First, we conducted interviews with stakeholders who were familiar with the health information exchange system to inform the development of a measure of benefits and challenges of the use of this system. Second, using this measure we conducted a survey of current and former users of the health information exchange system using a modified Dillman method. 105 current and former users completed the survey. The results showed information quality, ease of completing tasks and clinical process improvement as key benefits that reduced workload and improved patient care.  Challenges related to system reliability, quality of reports and service quality increased workload and decreased impact on care, though the effect of the challenges was smaller than that of the benefits.  Even very limited health information exchange capabilities can improve outcomes for primary care users.  Improving perceptions of benefits may be even more important the removing challenges to use, though it is likely that a threshold of quality must be achieved for this to be true.

Reading behind the Lines: The Factors Affecting the Text Reception Threshold in Hearing Aid Users

ERIC Educational Resources Information Center

Zekveld, Adriana A.; Pronk, Marieke; Danielsson, Henrik; Rönnberg, Jerker

2018-01-01

Purpose: The visual Text Reception Threshold (TRT) test (Zekveld et al., 2007) has been designed to assess modality-general factors relevant for speech perception in noise. In the last decade, the test has been adopted in audiology labs worldwide. The 1st aim of this study was to examine which factors best predict interindividual differences in…

New Measures of Masked Text Recognition in Relation to Speech-in-Noise Perception and Their Associations with Age and Cognitive Abilities

ERIC Educational Resources Information Center

Besser, Jana; Zekveld, Adriana A.; Kramer, Sophia E.; Ronnberg, Jerker; Festen, Joost M.

2012-01-01

Purpose: In this research, the authors aimed to increase the analogy between Text Reception Threshold (TRT; Zekveld, George, Kramer, Goverts, & Houtgast, 2007) and Speech Reception Threshold (SRT; Plomp & Mimpen, 1979) and to examine the TRT's value in estimating cognitive abilities that are important for speech comprehension in noise. Method: The…

Anaerobic threshold determination through ventilatory and electromyographics parameters.

PubMed

Gassi, E R; Bankoff, A D P

2010-01-01

The aim of present study was to compare the alterations in electromyography signs with Ventilatory Threshold (VT). Had been part of the study eight men, amateur cyclists and triathletes (25.25 +/- 6.96 years), that they had exercised themselves in a mechanical cicloergometer, a cadence of 80 RPM and with the increased intensity being in 25 W/min until the exhaustion. The VT was determined by a non-linear increase in VE/VO2 without any increase in VE/VCO2 and compared with the intensity corresponding to break point of amplitude EMG sign during the incremental exercise. The EMG--Fatigue Threshold (FT) and Ventilatory Threshold (VT) parameters used were the power, the time, absolute and relative VO2, ventilation (VE), the heart hate (HH) and the subjective perception of the effort. The results had not shown to difference in none of the variable selected for the corresponding intensity to VT and FT--EMG of the muscles lateralis vastus and femoris rectus. The parameters used in the comparison between the electromyographic indicators and ventilatory were the load, the time, absolute VO2 and relative to corporal mass, to ventilation (VE), the heart frequency (HH) and the Subjective Perception of the Effort (SPE).

Effect of 24 hours of sleep deprivation on auditory and linguistic perception: a comparison among young controls, sleep-deprived participants, dyslexic readers, and aging adults.

PubMed

Fostick, Leah; Babkoff, Harvey; Zukerman, Gil

2014-06-01

To test the effects of 24 hr of sleep deprivation on auditory and linguistic perception and to assess the magnitude of this effect by comparing such performance with that of aging adults on speech perception and with that of dyslexic readers on phonological awareness. Fifty-five sleep-deprived young adults were compared with 29 aging adults (older than 60 years) and with 18 young controls on auditory temporal order judgment (TOJ) and on speech perception tasks (Experiment 1). The sleep deprived were also compared with 51 dyslexic readers and with the young controls on TOJ and phonological awareness tasks (One-Minute Test for Pseudowords, Phoneme Deletion, Pig Latin, and Spoonerism; Experiment 2). Sleep deprivation resulted in longer TOJ thresholds, poorer speech perception, and poorer nonword reading compared with controls. The TOJ thresholds of the sleep deprived were comparable to those of the aging adults, but their pattern of speech performance differed. They also performed better on TOJ and phonological awareness than dyslexic readers. A variety of linguistic skills are affected by sleep deprivation. The comparison of sleep-deprived individuals with other groups with known difficulties in these linguistic skills might suggest that different groups exhibit common difficulties.

Orientation perception in Williams Syndrome: discrimination and integration

PubMed Central

Palomares, Melanie; Landau, Barbara; Egeth, Howard

2009-01-01

Williams Syndrome (WS) is a rare neurodevelopmental disorder, which stems from a genetic deletion on chromosome 7 that causes a profound weakness in visuospatial cognition. Our current study explores how orientation perception may contribute to the visuospatial deficits in WS. In Experiment 1, we found that WS individuals and normal 3-4 year olds had similar orientation discrimination thresholds and had similar prevalence of mirror-reversal errors for diagonal targets (±45 deg). In Experiment 2, we asked whether this immaturity in orientation discrimination would also be reflected in a task requiring integration of oriented elements. We found that sensitivities of WS individuals for detecting orientation-defined contours were higher than sensitivities of normal 3-4 year olds, and were not significantly different from sensitivities of normal adults. Together, these results suggest that orientation discrimination and orientation integration have different maturational trajectories in normal development and different susceptibilities to damage in WS, which may reflect largely separate visuospatial mechanisms. PMID:19231058

Nonconscious semantic processing of emotional words modulates conscious access

PubMed Central

Gaillard, Raphaël; Del Cul, Antoine; Naccache, Lionel; Vinckier, Fabien; Cohen, Laurent; Dehaene, Stanislas

2006-01-01

Whether masked words can be processed at a semantic level remains a controversial issue in cognitive psychology. Although recent behavioral studies have demonstrated masked semantic priming for number words, attempts to generalize this finding to other categories of words have failed. Here, as an alternative to subliminal priming, we introduce a sensitive behavioral method to detect nonconscious semantic processing of words. The logic of this method consists of presenting words close to the threshold for conscious perception and examining whether their semantic content modulates performance in objective and subjective tasks. Our results disclose two independent sources of modulation of the threshold for access to consciousness. First, prior conscious perception of words increases the detection rate of the same words when they are subsequently presented with stronger masking. Second, the threshold for conscious access is lower for emotional words than for neutral ones, even for words that have not been previously consciously perceived, thus implying that written words can receive nonconscious semantic processing. PMID:16648261

Pain perception and nonsuicidal self-injury: a laboratory investigation.

PubMed

Hooley, Jill M; Ho, Doreen T; Slater, Joshua; Lockshin, Amanda

2010-07-01

People who engage in self-injurious behaviors such as cutting and burning may have altered pain perception. Using a community sample, we examined group differences in pain threshold and pain endurance between participants who self-injured and control participants who were exposed to pressure pain applied to the finger. Participants who self-injured had higher pain thresholds (time to report pain) and endured pain for longer than control participants. Among participants who self-injured, those with longer histories of self-injury had higher pain thresholds. Duration of self-injury was unrelated to pain endurance. Instead, greater pain endurance was predicted by higher levels of introversion and neuroticism and by more negative beliefs about one's self-worth. A highly self-critical cognitive style was the strongest predictor of prolonged pain endurance. People who self-injure may regard suffering and pain as something that they deserve. Our findings also have implications for understanding factors that might be involved in the development and maintenance of self-injury. PsycINFO Database Record (c) 2010 APA, all rights reserved

Improving Sensorimotor Function Using Stochastic Vestibular Stimulation

NASA Technical Reports Server (NTRS)

Galvan, R. C.; Clark, T. K.; Merfeld, D. M.; Bloomberg, J. J.; Mulavara, A. P.; Oman, C. M.

2014-01-01

Astronauts experience sensorimotor changes during spaceflight, particularly during G-transition phases. Post flight sensorimotor changes may include postural and gait instability, spatial disorientation, and visual performance decrements, all of which can degrade operational capabilities of the astronauts and endanger the crew. Crewmember safety would be improved if these detrimental effects of spaceflight could be mitigated by a sensorimotor countermeasure and even further if adaptation to baseline could be facilitated. The goal of this research is to investigate the potential use of stochastic vestibular stimulation (SVS) as a technology to improve sensorimotor function. We hypothesize that low levels of SVS will improve sensorimotor performance through stochastic resonance (SR). The SR phenomenon occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. Two studies have been initiated to investigate the beneficial effects and potential practical usage of SVS. In both studies, electrical vestibular stimulation is applied via electrodes on the mastoid processes using a constant current stimulator. The first study aims to determine the repeatability of the effect of vestibular stimulation on sensorimotor performance and perception in order to better understand the practical use of SVS. The beneficial effect of low levels of SVS on balance performance has been shown in the past. This research uses the same balance task repeated multiple times within a day and across days to study the repeatability of the stimulation effects. The balance test consists of 50 sec trials in which the subject stands with his or her feet together, arms crossed, and eyes closed on compliant foam. Varying levels of SVS, ranging from 0-700 micro A, are applied across different trials. The subject-specific optimal SVS level is that which results in the best balance performance as measured by inertial measurement units placed on the upper and lower torso of the subjects. Additionally, each individual’s threshold for illusory motion perception of suprasensory electrical vestibular stimulation is measured multiple times within and across days to better understand how multiple SVS test methods compare. The second study aims to demonstrate stochastic resonance in the vestibular system using a perception based motion recognition task. This task measures an individual’s velocity threshold of motion recognition using a 6-degree of freedom Stewart platform and a 3-down/1-up staircase procedure. For this study, thresholds are determined using 150 trials in the upright, head-centered roll tilt motion direction at a 0.2 Hz frequency. We aim to demonstrate the characteristic bell shaped curve associated with stochastic resonance with each subject’s motion recognition thresholds at varying SVS levels ranging from 0 to 1500 micro A. The curve includes the individual’s baseline threshold with no SVS, optimal or minimal threshold at some mid-level of SVS, and finally degraded or increased threshold at a high SVS level. An additional aim is to formally retest each subject at his or her individual optimal SVS level on a different day than the original testing for additional validity. The overall purpose of this research is to further quantify the effects of SVS on various sensorimotor tasks and investigate the practical implications of its use in the context of human space flight so that it may be implemented in the future as a component of a comprehensive countermeasure plan for adaptation to G-transitions.

Pudendal and median nerve sensory perception threshold: a comparison between normative studies.

PubMed

Quaghebeur, Jörgen; Wyndaele, Jean Jacques

2014-12-01

For the evaluation of sensory innervation, normative data are necessary as a comparison. To compare our current perception thresholds (CPTs) with normative data from other research. Healthy volunteers were assessed for 2000, 250, and 5 Hz CPTs of the median and pudendal nerve and data were compared with other studies. Normative data in the studied group n = 41 (male: 21; female: 20) for the median nerve, 2 kHz, 250 Hz, and 5 Hz were respectively: 241.85 ± 67.72 (140-444); 106.27 ± 39.12 (45-229); 82.05 ± 43.40 (13-271). Pudendal nerve CPTs 250 Hz were: 126.44 ± 69.46 (6-333). For men 2 kHz: 349.95 ± 125.76 (100-588); 5 Hz: 132.67 ± 51.81 (59-249) and women 2 kHz:226.20 ± 119.65 (64-528); 5 Hz: 92.45 ± 44.66 (35-215). For the median nerve no statistical differences for gender were shown. For the pudendal nerve, only 250 Hz showed no difference for gender (t-test: 0.516). Comparison of our data with CPTs of other normative data showed no agreement for the pudendal nerve. For the median nerve only 2 kHz showed agreement in three studies and for 5 Hz with one study. Comparing normative data of multiple studies shows a variety of results and poor agreement. Therefore, referring to normative data of other studies should be handled with caution.

Evaluation of the 'Fitting to Outcomes eXpert' (FOX®) with established cochlear implant users.

PubMed

Buechner, Andreas; Vaerenberg, Bart; Gazibegovic, Dzemal; Brendel, Martina; De Ceulaer, Geert; Govaerts, Paul; Lenarz, Thomas

2015-01-01

To evaluate the possible impact of 'Fitting to Outcomes eXpert (FOX(®))' on cochlear implant (CI) fitting in a clinic with extensive experience of fitting a range of CI systems, as a way to assess whether a software tool such as FOX is able to complement standard clinical procedures. Ten adult post-lingually deafened and unilateral long-term users of the Advanced Bionics(TM) CI system (Clarion CII or HiRes 90K(TM)) underwent speech perception assessment with their current clinical program. One cycle 'iteration' of FOX optimization was performed and the program adjusted accordingly. After a month of using both clinical and FOX programs, a second iteration of FOX optimization was performed. Following this, the assessments were repeated without further acclimatization. FOX prescribed programming modifications in all subjects. Soundfield-aided thresholds were significantly lower for FOX than the clinical program. Group speech scores in noise were not significantly different between the two programs but three individual subjects had improved speech scores with the FOX MAP, two had worse speech scores, and five were the same. FOX provided a standardized approach to fitting based on outcome measures rather than comfort alone. The results indicated that for this group of well-fitted patients, FOX improved outcomes in some individuals. There were significant changes, both better and worse, in individual speech perception scores but median scores remained unchanged. Soundfield-aided thresholds were significantly improved for the FOX group.

The effect of intravesical oxybutynin on the ice water test and on electrical perception thresholds in patients with neurogenic detrusor overactivity.

PubMed

Van Meel, Tom David; De Wachter, Stefan; Wyndaele, Jean Jacques

2010-03-01

The C-fiber-mediated bladder-cooling reflex and the determination of the current perception thresholds (CPTs) permit to investigate afferent LUT pathways. They have both been proposed to detect and differentiate neurologic bladder dysfunction. This study evaluates, prospectively, the effect of oxybutynin, an antimuscarinic with direct antispasmodic effect on smooth muscle, on repeated ice water test (IWT) and CPTs in patients with a known incomplete neurogenic bladder. Patients with a known incomplete lesion of the bladder innervation, detrusor overactivity during cystometric bladder filling and a continuous positive response to repeated IWT were included. After the initial tests, 30 mg intravesical oxybutynin (1 mg/ml) was instilled and left in the bladder for 15 min. Afterwards CPTs and IWT were re-assessed. After the drug application, the bladder-cooling reflex could not be initiated, even after three instillations, in 16/17 patients. The bladder CPT increased from 29.7 +/- 11.3 to 39.1 +/- 15.7 mA after oxybutynin (P = 0.001). No difference was found in CPT of the left forearm (P = 0.208). Intravesical oxybutynin blocks the bladder-cooling reflex and increases but does not block CPT sensation in the bladder in most patients with incomplete neurogenic lesion and detrusor overactivity. These results help explain the clinical effect of intravesical oxybutynin in neurogenic patients. They also indicate that a pharmacological local influence on C-fiber-related activity can give different clinical effects. (c) 2009 Wiley-Liss, Inc.

Impact of Xanthylium Derivatives on the Color of White Wine.

PubMed

Bührle, Franziska; Gohl, Anita; Weber, Fabian

2017-08-19

Xanthylium derivatives are yellow to orange pigments with a glyoxylic acid bridge formed by dimerization of flavanols, which are built by oxidative cleavage of tartaric acid. Although their structure and formation under wine-like conditions are well established, knowledge about their color properties and their occurrence and importance in wine is deficient. Xanthylium cations and their corresponding esters were synthesized in a model wine solution and isolated via high-performance countercurrent chromatography (HPCCC) and solid phase extraction (SPE). A Three-Alternative-Forced-Choice (3-AFC) test was applied to reveal the color perception threshold of the isolated compounds in white wine. Their presence and color impact was assessed in 70 different wines (58 white and 12 rosé wines) by UHPLC-DAD-ESI-MS n and the storage stability in wine was determined. The thresholds in young Riesling wine were 0.57 mg/L (cations), 1.04 mg/L (esters) and 0.67 mg/L (1:1 ( w / w ) mixture), respectively. The low thresholds suggest a possible impact on white wine color, but concentrations in wines were below the threshold. The stability study showed the degradation of the compounds during storage under several conditions. Despite the low perception threshold, xanthylium derivatives might have no direct impact on white wine color, but might play a role in color formation as intermediate products in polymerization and browning.

Influence of capsaicin infusion on secondary peristalsis in patients with gastroesophageal reflux disease

PubMed Central

Yi, Chih-Hsun; Lei, Wei-Yi; Hung, Jui-Sheng; Liu, Tso-Tsai; Chen, Chien-Lin; Pace, Fabio

2016-01-01

AIM To determine whether capsaicin infusion could influence heartburn perception and secondary peristalsis in patients with gastroesophageal reflux disease (GERD). METHODS Secondary peristalsis was performed with slow and rapid mid-esophageal injections of air in 10 patients with GERD. In a first protocol, saline and capsaicin-containing red pepper sauce infusions were randomly performed, whereas 2 consecutive sessions of capsaicin-containing red pepper sauce infusions were performed in a second protocol. Tested solutions including 5 mL of red pepper sauce diluted with 15 mL of saline and 20 mL of 0.9% saline were infused into the mid-esophagus via the manometric catheter at a rate of 10 mL/min with a randomized and double-blind fashion. During each study protocol, perception of heartburn, threshold volumes and peristaltic parameters for secondary peristalsis were analyzed and compared between different stimuli. RESULTS Infusion of capsaicin significantly increased heartburn perception in patients with GERD (P < 0.001), whereas repeated capsaicin infusion significantly reduced heartburn perception (P = 0.003). Acute capsaicin infusion decreased threshold volume of secondary peristalsis (P = 0.001) and increased its frequency (P = 0.01) during rapid air injection. The prevalence of GERD patients with successive secondary peristalsis during slow air injection significantly increased after capsaicin infusion (P = 0.001). Repeated capsaicin infusion increased threshold volume of secondary peristalsis (P = 0.002) and reduced the frequency of secondary peristalsis (P = 0.02) during rapid air injection. CONCLUSION Acute esophageal exposure to capsaicin enhances heartburn sensation and promotes secondary peristalsis in gastroesophageal reflux disease, but repetitive capsaicin infusion reverses these effects. PMID:28018112

A real signal and its states

NASA Astrophysics Data System (ADS)

Basiladze, S. G.

2017-05-01

The paper describes the general physical theory of signals, carriers of information, which supplements Shannon's abstract classical theory and is applicable in much broader fields, including nuclear physics. It is shown that in the absence of classical noise its place should be taken by the physical threshold of signal perception for objects of both macrocosm and microcosm. The signal perception threshold allows the presence of subthreshold (virtual) signal states. For these states, Boolean algebra of logic ( A = 0/1) is transformed into the "algebraic logic" of probabilities (0 ≤ a ≤ 1). The similarity and difference of virtual states of macroand microsignals are elucidated. "Real" and "quantum" information for computers is considered briefly. The maximum information transmission rate is estimated based on physical constants.

Contributions of adaptation currents to dynamic spike threshold on slow timescales: Biophysical insights from conductance-based models

NASA Astrophysics Data System (ADS)

Yi, Guosheng; Wang, Jiang; Wei, Xile; Deng, Bin; Li, Huiyan; Che, Yanqiu

2017-06-01

Spike-frequency adaptation (SFA) mediated by various adaptation currents, such as voltage-gated K+ current (IM), Ca2+-gated K+ current (IAHP), or Na+-activated K+ current (IKNa), exists in many types of neurons, which has been shown to effectively shape their information transmission properties on slow timescales. Here we use conductance-based models to investigate how the activation of three adaptation currents regulates the threshold voltage for action potential (AP) initiation during the course of SFA. It is observed that the spike threshold gets depolarized and the rate of membrane depolarization (dV/dt) preceding AP is reduced as adaptation currents reduce firing rate. It is indicated that the presence of inhibitory adaptation currents enables the neuron to generate a dynamic threshold inversely correlated with preceding dV/dt on slower timescales than fast dynamics of AP generation. By analyzing the interactions of ionic currents at subthreshold potentials, we find that the activation of adaptation currents increase the outward level of net membrane current prior to AP initiation, which antagonizes inward Na+ to result in a depolarized threshold and lower dV/dt from one AP to the next. Our simulations demonstrate that the threshold dynamics on slow timescales is a secondary effect caused by the activation of adaptation currents. These findings have provided a biophysical interpretation of the relationship between adaptation currents and spike threshold.

Changing mothers' perception of infant emotion: a pilot study.

PubMed

Carnegie, Rebecca; Shepherd, C; Pearson, R M; Button, K S; Munafò, M R; Evans, J; Penton-Voak, I S

2016-02-01

Cognitive bias modification (CBM) techniques, which experimentally retrain abnormal processing of affective stimuli, are becoming established for various psychiatric disorders. Such techniques have not yet been applied to maternal processing of infant emotion, which is affected by various psychiatric disorders. In a pilot study, mothers of children under 3 years old (n =  2) were recruited and randomly allocated to one of three training exercises, aiming either to increase or decrease their threshold of perceiving distress in a morphed continuum of 15 infant facial images. Differences between pre- and post-training threshold were analysed between and within subjects. Compared to baseline thresholds, the threshold for perceiving infant distress decreased in the lowered threshold group (mean difference -1.7 frames, 95 % confidence intervals (CI) -3.1 to -0.3, p = 0.02), increased in the raised threshold group (1.3 frames, 95 % CI 0.6 to 2.1, p < 0.01) and was unchanged in the control group (0.1 frames, 95 % CI -0.8 to 1.1, p = 0.80). Between-group differences were similarly robust in regression models and were not attenuated by potential confounders. The findings suggest that it is possible to change the threshold at which mothers perceive ambiguous infant faces as distressed, either to increase or decrease sensitivity to distress. This small study was intended to provide proof of concept (i.e. that it is possible to alter a mother's perception of infant distress). Questions remain as to whether the effects persist beyond the immediate experimental session, have an impact on maternal behaviour and could be used in clinical samples to improve maternal sensitivity and child outcomes.

Predicting the threshold of pulse-train electrical stimuli using a stochastic auditory nerve model: the effects of stimulus noise.

PubMed

Xu, Yifang; Collins, Leslie M

2004-04-01

The incorporation of low levels of noise into an electrical stimulus has been shown to improve auditory thresholds in some human subjects (Zeng et al., 2000). In this paper, thresholds for noise-modulated pulse-train stimuli are predicted utilizing a stochastic neural-behavioral model of ensemble fiber responses to bi-phasic stimuli. The neural refractory effect is described using a Markov model for a noise-free pulse-train stimulus and a closed-form solution for the steady-state neural response is provided. For noise-modulated pulse-train stimuli, a recursive method using the conditional probability is utilized to track the neural responses to each successive pulse. A neural spike count rule has been presented for both threshold and intensity discrimination under the assumption that auditory perception occurs via integration over a relatively long time period (Bruce et al., 1999). An alternative approach originates from the hypothesis of the multilook model (Viemeister and Wakefield, 1991), which argues that auditory perception is based on several shorter time integrations and may suggest an NofM model for prediction of pulse-train threshold. This motivates analyzing the neural response to each individual pulse within a pulse train, which is considered to be the brief look. A logarithmic rule is hypothesized for pulse-train threshold. Predictions from the multilook model are shown to match trends in psychophysical data for noise-free stimuli that are not always matched by the long-time integration rule. Theoretical predictions indicate that threshold decreases as noise variance increases. Theoretical models of the neural response to pulse-train stimuli not only reduce calculational overhead but also facilitate utilization of signal detection theory and are easily extended to multichannel psychophysical tasks.

Optimal Stimulus Amplitude for Vestibular Stochastic Stimulation to Improve Sensorimotor Function

NASA Technical Reports Server (NTRS)

Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Cohen, H.; Bloomberg, J. J.;

The Effect of Frequency Transposition on Speech Perception in Adolescents and Young Adults with Profound Hearing Loss

ERIC Educational Resources Information Center

Gou, J.; Smith, J.; Valero, J.; Rubio, I.

2011-01-01

This paper reports on a clinical trial evaluating outcomes of a frequency-lowering technique for adolescents and young adults with severe to profound hearing impairment. Outcomes were defined by changes in aided thresholds, speech perception, and acceptance. The participants comprised seven young people aged between 13 and 25 years. They were…

Areola-nipple perception threshold to faradic electricity: a new measure of sensibility of the breasts.

PubMed

Prado, Arturo; Andrades, Patricio; Benitez, Susana; Parada, Franciso

2008-09-01

We describe a new method to study the sensibility of the nipple-areola complex of the breast with faradic electricity delivered through an electromyographic device used to monitor peripheral nerve conduction. The objective results of faradic pulses (2-50 mA per pulse) delivered to the nipple-areola complex of the breast through a Nihon-Kohden II machine (Evoked potential/Electromyographs, Nihon-Kohden Co., Japan) were evaluated in normal volunteers to get a basal measure that was defined by the patient as "a soft electric discharge." The measures were recorded and their output discharges averaged (at least 5 to each complex). Twenty-eight volunteers with normal breasts, 28 patients with breast hypertrophy before and after breast reduction, and 28 patients before and after breast augmentation were studied. The faradic pulses were perceived from 1.5 to 3.5 mA in the areola and from 3 to 5.5 mA in the nipple in the control group and from 4.5 to 7.0 mA in the areola and from 6.5 to 9.5 mA in the nipple in the breast hypertrophy group with no significant changes before and after surgery. In the breast augmentation group the faradic pulses were very similar to the volunteers that had normal breasts, but 13 months after breast augmentation with silicone gel prosthesis, a difference was found because all the patients had a higher threshold and three cases had lost sensibility of the nipple-areola complex. In normal breasts the areola had a lower threshold for faradic pulses compared to the nipple. Hypertrophic breasts had a higher threshold to the faradic stimulation than normal subjects in the pre- and postoperative period. Hypoplastic breasts before breast augmentation had a perception threshold similar to that of the normal volunteers but after breast augmentation this perception was much higher.

AREA RADIATION MONITOR

DOEpatents

Manning, F.W.; Groothuis, S.E.; Lykins, J.H.; Papke, D.M.

1962-06-12

S>An improved area radiation dose monitor is designed which is adapted to compensate continuously for background radiation below a threshold dose rate and to give warning when the dose integral of the dose rate of an above-threshold radiation excursion exceeds a selected value. This is accomplished by providing means for continuously charging an ionization chamber. The chamber provides a first current proportional to the incident radiation dose rate. Means are provided for generating a second current including means for nulling out the first current with the second current at all values of the first current corresponding to dose rates below a selected threshold dose rate value. The second current has a maximum value corresponding to that of the first current at the threshold dose rate. The excess of the first current over the second current, which occurs above the threshold, is integrated and an alarm is given at a selected integrated value of the excess corresponding to a selected radiation dose. (AEC)

Effect of signal to noise ratio on the speech perception ability of older adults

PubMed Central

Shojaei, Elahe; Ashayeri, Hassan; Jafari, Zahra; Zarrin Dast, Mohammad Reza; Kamali, Koorosh

2016-01-01

Background: Speech perception ability depends on auditory and extra-auditory elements. The signal- to-noise ratio (SNR) is an extra-auditory element that has an effect on the ability to normally follow speech and maintain a conversation. Speech in noise perception difficulty is a common complaint of the elderly. In this study, the importance of SNR magnitude as an extra-auditory effect on speech perception in noise was examined in the elderly. Methods: The speech perception in noise test (SPIN) was conducted on 25 elderly participants who had bilateral low–mid frequency normal hearing thresholds at three SNRs in the presence of ipsilateral white noise. These participants were selected by available sampling method. Cognitive screening was done using the Persian Mini Mental State Examination (MMSE) test. Results: Independent T- test, ANNOVA and Pearson Correlation Index were used for statistical analysis. There was a significant difference in word discrimination scores at silence and at three SNRs in both ears (p≤0.047). Moreover, there was a significant difference in word discrimination scores for paired SNRs (0 and +5, 0 and +10, and +5 and +10 (p≤0.04)). No significant correlation was found between age and word recognition scores at silence and at three SNRs in both ears (p≥0.386). Conclusion: Our results revealed that decreasing the signal level and increasing the competing noise considerably reduced the speech perception ability in normal hearing at low–mid thresholds in the elderly. These results support the critical role of SNRs for speech perception ability in the elderly. Furthermore, our results revealed that normal hearing elderly participants required compensatory strategies to maintain normal speech perception in challenging acoustic situations. PMID:27390712

How parents perceive screen viewing in their 5-6 year old child within the context of their own screen viewing time: a mixed-methods study.

PubMed

Thompson, Janice L; Sebire, Simon J; Kesten, Joanna M; Zahra, Jesmond; Edwards, Mark; Solomon-Moore, Emma; Jago, Russell

2017-06-01

Few studies have examined parental perceptions of their child's screen-viewing (SV) within the context of parental SV time. This study qualitatively examined parents' perceptions of their 5-6-year-old child's SV within the context of their own quantitatively measured SV. A mixed-methods design employed semi-structured telephone interviews, demographic and SV questionnaires, objectively-measured physical activity and sedentary time. Deductive content analysis was used to explore parents' perceptions of, and concerns about, their child's SV, and management of their child's SV. Comparisons were made between parent-child dyads reporting low (<2-h per day) versus high SV time. Fifty-three parents were interviewed (94.3% mothers), with 52 interviews analysed. Fifteen parent-child dyads (28.8%) exceeded the 2-h SV threshold on both weekdays and weekend days; 5 parent-child dyads (9.6%) did not exceed this threshold. The remaining 32 dyads reported a combination of parent or child exceeding/not exceeding the SV threshold on either weekdays or weekend days. Three main themes distinguished the 15 parent-child dyads exceeding the SV threshold from the 5 dyads that did not: 1) parents' personal SV-related views and behaviours; 2) the family SV environment; and 3) setting SV rules and limits. Parents in the dyads not exceeding the SV threshold prioritized and engaged with their children in non-SV behaviours for relaxation, set limits around their own and their child's SV-related behaviours, and described an environment supportive of physical activity. Parents in the dyads exceeding the SV threshold were more likely to prioritise SV as a shared family activity, and described a less structured SV environment with minimal rule setting, influenced their child's need for relaxation time. The majority of parents in this study who exceeded the SV threshold expressed minimal concern and a relaxed approach to managing SV for themselves and their child(ren), suggesting a need to raise awareness amongst these parents about the time they spend engaging in SV. Parents may understand their SV-related parenting practices more clearly if they are encouraged to examine their own SV behaviours. Designing interventions aimed to create environments that are less supportive of SV, with more structured approaches to SV parenting strategies are warranted.

Extrafoveally applied flashing light affects contrast thresholds of achromatic and S-cone isolating, but not L-M cone modulated stimuli.

PubMed

Őze, A; Puszta, A; Buzás, P; Kóbor, P; Braunitzer, G; Nagy, A

2018-06-21

Flashing light stimulation is often used to investigate the visual system. However, the magnitude of the effect of this stimulus on the various subcortical pathways is not well investigated. The signals of conscious vision are conveyed by the magnocellular, parvocellular and koniocellular pathways. Parvocellular and koniocellular pathways (or more precisely, the L-M opponent and S-cone isolating channels) can be accessed by isoluminant red-green (L-M) and S-cone isolating stimuli, respectively. The main goal of the present study was to explore how costimulation with strong white extrafoveal light flashes alters the perception of stimuli specific to these pathways. Eleven healthy volunteers with negative neurological and ophthalmological history were enrolled for the study. Isoluminance of L-M and S-cone isolating sine-wave gratings was set individually, using the minimum motion procedure. The contrast thresholds for these stimuli as well as for achromatic gratings were determined by an adaptive staircase procedure where subjects had to indicate the orientation (horizontal, oblique or vertical) of the gratings. Thresholds were then determined again while a strong white peripheral light flash was presented 50 ms before each trial. Peripheral light flashes significantly (p < 0.05) increased the contrast thresholds of the achromatic and S-cone isolating stimuli. The threshold elevation was especially marked in case of the achromatic stimuli. However, the contrast threshold for the L-M stimuli was not significantly influenced by the light flashes. We conclude that extrafoveally applied light flashes influence predominantly the perception of achromatic stimuli. Copyright © 2018 Elsevier B.V. All rights reserved.

Preliminary test of cigarette nicotine discrimination threshold in non-dependent versus dependent smokers

PubMed Central

Perkins, Kenneth A.; Kunkle, Nicole; Karelitz, Joshua L.

2017-01-01

Background Despite its potential for understanding tobacco dependence, behavioral discrimination of nicotine via smoking has not been formally examined as a function of nicotine dependence level. Methods Spectrum research cigarettes were used to compare non-dependent with dependent smokers on the lowest content of nicotine they could discriminate (i.e., “threshold”). Dependent (n=21; 16 M, 5 F) or non-dependent (n=7; 4 M, 3 F) smokers were tested on ability to discriminate between cigarettes with nicotine contents of 17, 11, 5, 2, and 1 mg/g, one per session, from an “ultra-low” cigarette with 0.4 mg/g (all had 9–10 mg “tar”). All abstained from smoking overnight prior to sessions, and number of sessions was determined by the lowest nicotine content they could reliably discriminate from the ultra-low on >80% of trials (i.e., ≥5 of 6). Subjective perceptions and cigarette choice behavior were also assessed and related to discrimination behavior. Results Discrimination thresholds (and most perceptions) did not differ between dependent and non-dependent smokers, with median thresholds of 11 mg/g for both subgroups. Yet, “liking” and puff choice for threshold cigarettes were greater in dependent but not non-dependent smokers, while cigarettes with nicotine contents below threshold did not support “liking” or choice in both groups. Conclusions In sum, this preliminary study suggests threshold for discriminating nicotine via smoking may not vary by dependence level, and further study is needed to confirm that cigarettes unable to be discriminated are also not reinforcing. PMID:28380366

The effect of symmetrical and asymmetrical hearing impairment on music quality perception.

PubMed

Cai, Yuexin; Zhao, Fei; Chen, Yuebo; Liang, Maojin; Chen, Ling; Yang, Haidi; Xiong, Hao; Zhang, Xueyuan; Zheng, Yiqing

2016-09-01

The purpose of this study was to investigate the effect of symmetrical, asymmetrical and unilateral hearing impairment on music quality perception. Six validated music pieces in the categories of classical music, folk music and pop music were used to assess music quality in terms of its 'pleasantness', 'naturalness', 'fullness', 'roughness' and 'sharpness'. 58 participants with sensorineural hearing loss [20 with unilateral hearing loss (UHL), 20 with bilateral symmetrical hearing loss (BSHL) and 18 with bilateral asymmetrical hearing loss (BAHL)] and 29 normal hearing (NH) subjects participated in the present study. Hearing impaired (HI) participants had greater difficulty in overall music quality perception than NH participants. Participants with BSHL rated music pleasantness and naturalness to be higher than participants with BAHL. Moreover, the hearing thresholds of the better ears from BSHL and BAHL participants as well as the hearing thresholds of the worse ears from BSHL participants were negatively correlated to the pleasantness and naturalness perception. HI participants rated the familiar music pieces higher than unfamiliar music pieces in the three music categories. Music quality perception in participants with hearing impairment appeared to be affected by symmetry of hearing loss, degree of hearing loss and music familiarity when they were assessed using the music quality rating test (MQRT). This indicates that binaural symmetrical hearing is important to achieve a high level of music quality perception in HI listeners. This emphasizes the importance of provision of bilateral hearing assistive devices for people with asymmetrical hearing impairment.

Tone perception in Mandarin-speaking school age children with otitis media with effusion

PubMed Central

McPherson, Bradley; Li, Caiwei; Yang, Feng

2017-01-01

Objectives The present study explored tone perception ability in school age Mandarin-speaking children with otitis media with effusion (OME) in noisy listening environments. The study investigated the interaction effects of noise, tone type, age, and hearing status on monaural tone perception, and assessed the application of a hierarchical clustering algorithm for profiling hearing impairment in children with OME. Methods Forty-one children with normal hearing and normal middle ear status and 84 children with OME with or without hearing loss participated in this study. The children with OME were further divided into two subgroups based on their severity and pattern of hearing loss using a hierarchical clustering algorithm. Monaural tone recognition was measured using a picture-identification test format incorporating six sets of monosyllabic words conveying four lexical tones under speech spectrum noise, with the signal-to-noise ratio (SNR) conditions ranging from -9 to -21 dB. Results Linear correlation indicated tone recognition thresholds of children with OME were significantly correlated with age and pure tone hearing thresholds at every frequency tested. Children with hearing thresholds less affected by OME performed similarly to their peers with normal hearing. Tone recognition thresholds of children with auditory status more affected by OME were significantly inferior to those of children with normal hearing or with minor hearing loss. Younger children demonstrated poorer tone recognition performance than older children with OME. A mixed design repeated-measure ANCOVA showed significant main effects of listening condition, hearing status, and tone type on tone recognition. Contrast comparisons revealed that tone recognition scores were significantly better under -12 dB SNR than under -15 dB SNR conditions and tone recognition scores were significantly worse under -18 dB SNR than those obtained under -15 dB SNR conditions. Tone 1 was the easiest tone to identify and Tone 3 was the most difficult tone to identify for all participants, when considering -12, -15, and -18 dB SNR as within-subject variables. The interaction effect between hearing status and tone type indicated that children with greater levels of OME-related hearing loss had more impaired tone perception of Tone 1 and Tone 2 compared to their peers with lesser levels of OME-related hearing loss. However, tone perception of Tone 3 and Tone 4 remained similar among all three groups. Tone 2 and Tone 3 were the most perceptually difficult tones for children with or without OME-related hearing loss in all listening conditions. Conclusions The hierarchical clustering algorithm demonstrated usefulness in risk stratification for tone perception deficiency in children with OME-related hearing loss. There was marked impairment in tone perception in noise for children with greater levels of OME-related hearing loss. Monaural lexical tone perception in younger children was more vulnerable to noise and OME-related hearing loss than that in older children. PMID:28829840

Tone perception in Mandarin-speaking school age children with otitis media with effusion.

PubMed

Cai, Ting; McPherson, Bradley; Li, Caiwei; Yang, Feng

2017-01-01

The present study explored tone perception ability in school age Mandarin-speaking children with otitis media with effusion (OME) in noisy listening environments. The study investigated the interaction effects of noise, tone type, age, and hearing status on monaural tone perception, and assessed the application of a hierarchical clustering algorithm for profiling hearing impairment in children with OME. Forty-one children with normal hearing and normal middle ear status and 84 children with OME with or without hearing loss participated in this study. The children with OME were further divided into two subgroups based on their severity and pattern of hearing loss using a hierarchical clustering algorithm. Monaural tone recognition was measured using a picture-identification test format incorporating six sets of monosyllabic words conveying four lexical tones under speech spectrum noise, with the signal-to-noise ratio (SNR) conditions ranging from -9 to -21 dB. Linear correlation indicated tone recognition thresholds of children with OME were significantly correlated with age and pure tone hearing thresholds at every frequency tested. Children with hearing thresholds less affected by OME performed similarly to their peers with normal hearing. Tone recognition thresholds of children with auditory status more affected by OME were significantly inferior to those of children with normal hearing or with minor hearing loss. Younger children demonstrated poorer tone recognition performance than older children with OME. A mixed design repeated-measure ANCOVA showed significant main effects of listening condition, hearing status, and tone type on tone recognition. Contrast comparisons revealed that tone recognition scores were significantly better under -12 dB SNR than under -15 dB SNR conditions and tone recognition scores were significantly worse under -18 dB SNR than those obtained under -15 dB SNR conditions. Tone 1 was the easiest tone to identify and Tone 3 was the most difficult tone to identify for all participants, when considering -12, -15, and -18 dB SNR as within-subject variables. The interaction effect between hearing status and tone type indicated that children with greater levels of OME-related hearing loss had more impaired tone perception of Tone 1 and Tone 2 compared to their peers with lesser levels of OME-related hearing loss. However, tone perception of Tone 3 and Tone 4 remained similar among all three groups. Tone 2 and Tone 3 were the most perceptually difficult tones for children with or without OME-related hearing loss in all listening conditions. The hierarchical clustering algorithm demonstrated usefulness in risk stratification for tone perception deficiency in children with OME-related hearing loss. There was marked impairment in tone perception in noise for children with greater levels of OME-related hearing loss. Monaural lexical tone perception in younger children was more vulnerable to noise and OME-related hearing loss than that in older children.

Cocaine acute "binge" administration results in altered thalamocortical interactions in mice.

PubMed

Urbano, Francisco J; Bisagno, Verónica; Wikinski, Silvia I; Uchitel, Osvaldo D; Llinás, Rodolfo R

2009-10-15

Abnormalities in both thalamic and cortical areas have been reported in human cocaine addicts with noninvasive functional magnetic resonance imaging. Given the substantial involvement of the thalamocortical system in sensory processing and perception, we defined electrophysiology-based protocols to attempt a characterization of cocaine effects on thalamocortical circuits. Thalamocortical function was studied in vivo and in vitro in mice after cocaine "binge" administration. In vivo awake electroencephalography (EEG) was implemented in mice injected with saline, 1 hour or 24 hours after the last cocaine "binge" injection. In vitro current- and voltage-clamp whole-cell patch-clamp recordings were performed from slices including thalamic relay ventrobasal (VB) neurons. In vivo EEG recordings after cocaine "binge" administration showed a significant increment, compared with saline, in low frequencies while observing no changes in high-frequency gamma activity. In vitro patch recordings from VB neurons after cocaine "binge" administration showed low threshold spikes activation at more negative membrane potentials and increments in both I(h) and low voltage activated T-type calcium currents. Also, a 10-mV negative shift on threshold activation level of T-type current and a remarkable increment in both frequency and amplitudes of gamma-aminobutyric acid-A-mediated minis were observed. Our data indicate that thalamocortical dysfunctions observed in cocaine abusers might be due to two distinct but additive events: 1) increased low frequency oscillatory thalamocortical activity, and 2) overinhibition of VB neurons that can abnormally "lock" the whole thalamocortical system at low frequencies.

Sensitivity and Bias in Decision-Making under Risk: Evaluating the Perception of Reward, Its Probability and Value

PubMed Central

Sharp, Madeleine E.; Viswanathan, Jayalakshmi; Lanyon, Linda J.; Barton, Jason J. S.

2012-01-01

Background There are few clinical tools that assess decision-making under risk. Tests that characterize sensitivity and bias in decisions between prospects varying in magnitude and probability of gain may provide insights in conditions with anomalous reward-related behaviour. Objective We designed a simple test of how subjects integrate information about the magnitude and the probability of reward, which can determine discriminative thresholds and choice bias in decisions under risk. Design/Methods Twenty subjects were required to choose between two explicitly described prospects, one with higher probability but lower magnitude of reward than the other, with the difference in expected value between the two prospects varying from 3 to 23%. Results Subjects showed a mean threshold sensitivity of 43% difference in expected value. Regarding choice bias, there was a ‘risk premium’ of 38%, indicating a tendency to choose higher probability over higher reward. An analysis using prospect theory showed that this risk premium is the predicted outcome of hypothesized non-linearities in the subjective perception of reward value and probability. Conclusions This simple test provides a robust measure of discriminative value thresholds and biases in decisions under risk. Prospect theory can also make predictions about decisions when subjective perception of reward or probability is anomalous, as may occur in populations with dopaminergic or striatal dysfunction, such as Parkinson's disease and schizophrenia. PMID:22493669

Sensitivity and bias in decision-making under risk: evaluating the perception of reward, its probability and value.

PubMed

Sharp, Madeleine E; Viswanathan, Jayalakshmi; Lanyon, Linda J; Barton, Jason J S

2012-01-01

There are few clinical tools that assess decision-making under risk. Tests that characterize sensitivity and bias in decisions between prospects varying in magnitude and probability of gain may provide insights in conditions with anomalous reward-related behaviour. We designed a simple test of how subjects integrate information about the magnitude and the probability of reward, which can determine discriminative thresholds and choice bias in decisions under risk. Twenty subjects were required to choose between two explicitly described prospects, one with higher probability but lower magnitude of reward than the other, with the difference in expected value between the two prospects varying from 3 to 23%. Subjects showed a mean threshold sensitivity of 43% difference in expected value. Regarding choice bias, there was a 'risk premium' of 38%, indicating a tendency to choose higher probability over higher reward. An analysis using prospect theory showed that this risk premium is the predicted outcome of hypothesized non-linearities in the subjective perception of reward value and probability. This simple test provides a robust measure of discriminative value thresholds and biases in decisions under risk. Prospect theory can also make predictions about decisions when subjective perception of reward or probability is anomalous, as may occur in populations with dopaminergic or striatal dysfunction, such as Parkinson's disease and schizophrenia.

Cognitive abilities relate to self-reported hearing disability.

PubMed

Zekveld, Adriana A; George, Erwin L J; Houtgast, Tammo; Kramer, Sophia E

2013-10-01

In this explorative study, the authors investigated the relationship between auditory and cognitive abilities and self-reported hearing disability. Thirty-two adults with mild to moderate hearing loss completed the Amsterdam Inventory for Auditory Disability and Handicap (AIADH; Kramer, Kapteyn, Festen, & Tobi, 1996) and performed the Text Reception Threshold (TRT; Zekveld, George, Kramer, Goverts, & Houtgast, 2007) test as well as tests of spatial working memory (SWM) and visual sustained attention. Regression analyses examined the predictive value of age, hearing thresholds (pure-tone averages [PTAs]), speech perception in noise (speech reception thresholds in noise [SRTNs]), and the cognitive tests for the 5 AIADH factors. Besides the variance explained by age, PTA, and SRTN, cognitive abilities were related to each hearing factor. The reported difficulties with sound detection and speech perception in quiet were less severe for participants with higher age, lower PTAs, and better TRTs. Fewer sound localization and speech perception in noise problems were reported by participants with better SRTNs and smaller SWM. Fewer sound discrimination difficulties were reported by subjects with better SRTNs and TRTs and smaller SWM. The results suggest a general role of the ability to read partly masked text in subjective hearing. Large working memory was associated with more reported hearing difficulties. This study shows that besides auditory variables and age, cognitive abilities are related to self-reported hearing disability.

Noise Enhances Action Potential Generation in Mouse Sensory Neurons via Stochastic Resonance.

PubMed

Onorato, Irene; D'Alessandro, Giuseppina; Di Castro, Maria Amalia; Renzi, Massimiliano; Dobrowolny, Gabriella; Musarò, Antonio; Salvetti, Marco; Limatola, Cristina; Crisanti, Andrea; Grassi, Francesca

2016-01-01

Noise can enhance perception of tactile and proprioceptive stimuli by stochastic resonance processes. However, the mechanisms underlying this general phenomenon remain to be characterized. Here we studied how externally applied noise influences action potential firing in mouse primary sensory neurons of dorsal root ganglia, modelling a basic process in sensory perception. Since noisy mechanical stimuli may cause stochastic fluctuations in receptor potential, we examined the effects of sub-threshold depolarizing current steps with superimposed random fluctuations. We performed whole cell patch clamp recordings in cultured neurons of mouse dorsal root ganglia. Noise was added either before and during the step, or during the depolarizing step only, to focus onto the specific effects of external noise on action potential generation. In both cases, step + noise stimuli triggered significantly more action potentials than steps alone. The normalized power norm had a clear peak at intermediate noise levels, demonstrating that the phenomenon is driven by stochastic resonance. Spikes evoked in step + noise trials occur earlier and show faster rise time as compared to the occasional ones elicited by steps alone. These data suggest that external noise enhances, via stochastic resonance, the recruitment of transient voltage-gated Na channels, responsible for action potential firing in response to rapid step-wise depolarizing currents.

Noise Enhances Action Potential Generation in Mouse Sensory Neurons via Stochastic Resonance

PubMed Central

Onorato, Irene; D'Alessandro, Giuseppina; Di Castro, Maria Amalia; Renzi, Massimiliano; Dobrowolny, Gabriella; Musarò, Antonio; Salvetti, Marco; Limatola, Cristina; Crisanti, Andrea; Grassi, Francesca

2016-01-01

Noise can enhance perception of tactile and proprioceptive stimuli by stochastic resonance processes. However, the mechanisms underlying this general phenomenon remain to be characterized. Here we studied how externally applied noise influences action potential firing in mouse primary sensory neurons of dorsal root ganglia, modelling a basic process in sensory perception. Since noisy mechanical stimuli may cause stochastic fluctuations in receptor potential, we examined the effects of sub-threshold depolarizing current steps with superimposed random fluctuations. We performed whole cell patch clamp recordings in cultured neurons of mouse dorsal root ganglia. Noise was added either before and during the step, or during the depolarizing step only, to focus onto the specific effects of external noise on action potential generation. In both cases, step + noise stimuli triggered significantly more action potentials than steps alone. The normalized power norm had a clear peak at intermediate noise levels, demonstrating that the phenomenon is driven by stochastic resonance. Spikes evoked in step + noise trials occur earlier and show faster rise time as compared to the occasional ones elicited by steps alone. These data suggest that external noise enhances, via stochastic resonance, the recruitment of transient voltage-gated Na channels, responsible for action potential firing in response to rapid step-wise depolarizing currents. PMID:27525414

Salty Taste Acuity Is Affected by the Joint Action of αENaC A663T Gene Polymorphism and Available Zinc Intake in Young Women

PubMed Central

Noh, Hwayoung; Paik, Hee-Young; Kim, Jihye; Chung, Jayong

2013-01-01

Salty taste perception affects salt intake, of which excess amounts is a major public health concern. Gene polymorphisms in salty taste receptors, zinc status and their interaction may affect salty taste perception. In this study, we examined the relationships among the α-epithelial sodium channel (αENaC) A663T genotype, zinc intake, and salty taste perception including salty taste acuity and preference in healthy young adults. The αENaC A663T genotype was determined by the PCR-restriction fragment length polymorphism in 207 adults. Zinc intake was examined by one 24-h recall and a two-day dietary record. Salty taste acuity and preference were determined by measuring the salty taste recognition threshold and the preferred salinity of beansprout soup, respectively. Men had significantly higher thresholds and preferences for salty taste than women did (p < 0.05). In women, the salty taste threshold was significantly lower in the highest tertile of available zinc intake than in the lowest tertile (12.2 mM and 17.6 mM, respectively, p = 0.02). Interestingly, a significant inverse association between available zinc intake and salty taste threshold was found only in women with αENaC AA homozygotes (β = −0.833, p = 0.02), and no such association was found in T663 allele carriers. The salty taste preference was not associated with the αENaC A663T genotype or available zinc intake in either sex. In conclusion, our data suggest that gene-nutrient interactions between the αENaC A663T genotype and available zinc intake play a role in determining the salty taste acuity in young women. PMID:24317554

Effect of painless diabetic neuropathy on pressure pain hypersensitivity (hyperalgesia) after acute foot trauma

PubMed Central

Wienemann, Tobias; Chantelau, Ernst A.; Koller, Armin

2014-01-01

Introduction and objective Acute injury transiently lowers local mechanical pain thresholds at a limb. To elucidate the impact of painless (diabetic) neuropathy on this post-traumatic hyperalgesia, pressure pain perception thresholds after a skeletal foot trauma were studied in consecutive persons without and with neuropathy (i.e. history of foot ulcer or Charcot arthropathy). Design and methods A case–control study was done on 25 unselected clinical routine patients with acute unilateral foot trauma (cases: elective bone surgery; controls: sprain, toe fracture). Cases were 12 patients (11 diabetic subjects) with severe painless neuropathy and chronic foot pathology. Controls were 13 non-neuropathic persons. Over 1 week after the trauma, cutaneous pressure pain perception threshold (CPPPT) and deep pressure pain perception threshold (DPPPT) were measured repeatedly, adjacent to the injury and at the opposite foot (pinprick stimulators, Algometer II®). Results In the control group, post-traumatic DPPPT (but not CPPPT) at the injured foot was reduced by about 15–25%. In the case group, pre- and post-operative CPPPT and DPPPT were supranormal. Although DPPPT fell post-operatively by about 15–20%, it remained always higher than the post-traumatic DPPPT in the control group: over musculus abductor hallucis 615 kPa (kilopascal) versus 422 kPa, and over metatarsophalangeal joint 518 kPa versus 375 kPa (medians; case vs. control group); CPPPT did not decrease post-operatively. Conclusion Physiological nociception and post-traumatic hyperalgesia to pressure are diminished at the foot with severe painless (diabetic) neuropathy. A degree of post-traumatic hypersensitivity required to ‘pull away’ from any one, even innocuous, mechanical impact in order to avoid additional damage is, therefore, lacking. PMID:25397867

Contrast effects on speed perception for linear and radial motion.

PubMed

Champion, Rebecca A; Warren, Paul A

2017-11-01

Speed perception is vital for safe activity in the environment. However, considerable evidence suggests that perceived speed changes as a function of stimulus contrast, with some investigators suggesting that this might have meaningful real-world consequences (e.g. driving in fog). In the present study we investigate whether the neural effects of contrast on speed perception occur at the level of local or global motion processing. To do this we examine both speed discrimination thresholds and contrast-dependent speed perception for two global motion configurations that have matched local spatio-temporal structure. Specifically we compare linear and radial configurations, the latter of which arises very commonly due to self-movement. In experiment 1 the stimuli comprised circular grating patches. In experiment 2, to match stimuli even more closely, motion was presented in multiple local Gabor patches equidistant from central fixation. Each patch contained identical linear motion but the global configuration was either consistent with linear or radial motion. In both experiments 1 and 2, discrimination thresholds and contrast-induced speed biases were similar in linear and radial conditions. These results suggest that contrast-based speed effects occur only at the level of local motion processing, irrespective of global structure. This result is interpreted in the context of previous models of speed perception and evidence suggesting differences in perceived speed of locally matched linear and radial stimuli. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biophysical Insights into How Spike Threshold Depends on the Rate of Membrane Potential Depolarization in Type I and Type II Neurons

PubMed Central

Yi, Guo-Sheng; Wang, Jiang; Tsang, Kai-Ming; Wei, Xi-Le; Deng, Bin

2015-01-01

Dynamic spike threshold plays a critical role in neuronal input-output relations. In many neurons, the threshold potential depends on the rate of membrane potential depolarization (dV/dt) preceding a spike. There are two basic classes of neural excitability, i.e., Type I and Type II, according to input-output properties. Although the dynamical and biophysical basis of their spike initiation has been established, the spike threshold dynamic for each cell type has not been well described. Here, we use a biophysical model to investigate how spike threshold depends on dV/dt in two types of neuron. It is observed that Type II spike threshold is more depolarized and more sensitive to dV/dt than Type I. With phase plane analysis, we show that each threshold dynamic arises from the different separatrix and K+ current kinetics. By analyzing subthreshold properties of membrane currents, we find the activation of hyperpolarizing current prior to spike initiation is a major factor that regulates the threshold dynamics. The outward K+ current in Type I neuron does not activate at the perithresholds, which makes its spike threshold insensitive to dV/dt. The Type II K+ current activates prior to spike initiation and there is a large net hyperpolarizing current at the perithresholds, which results in a depolarized threshold as well as a pronounced threshold dynamic. These predictions are further attested in several other functionally equivalent cases of neural excitability. Our study provides a fundamental description about how intrinsic biophysical properties contribute to the threshold dynamics in Type I and Type II neurons, which could decipher their significant functions in neural coding. PMID:26083350

Oblique Orientation Discrimination Thresholds Are Superior in Those with a High Level of Autistic Traits

ERIC Educational Resources Information Center

Dickinson, Abigail; Jones, Myles; Milne, Elizabeth

2014-01-01

Enhanced low-level perception, although present in individuals with autism, is not seen in individuals with high, but non-clinical, levels of autistic traits (Brock et al.in "Percept Lond" 40(6):739. doi:10.1068/p6953, 2011). This is surprising, as many of the higher-level visual differences found in autism have been shown to correlate…

Measured Rattle Threshold of Residential House Windows

NASA Technical Reports Server (NTRS)

Sizov, Natalia; Schultz, Troy; Hobbs, Christopher; Klos, Jacob

2008-01-01

Window rattle is a common indoor noise effect in houses exposed to low frequency noise from such sources as railroads, blast noise and sonic boom. Human perception of rattle can be negative that is a motivating factor of the current research effort to study sonic boom induced window rattle. A rattle study has been conducted on residential houses containing windows of different construction at a variety of geographic locations within the United States. Windows in these houses were excited by a portable, high-powered loudspeaker and enclosure specifically designed to be mounted on the house exterior to cover an entire window. Window vibration was measured with accelerometers placed on different window components. Reference microphones were also placed inside the house and inside of the loudspeaker box. Swept sine excitation was used to identify the vibration threshold at which the response of the structure becomes non-linear and begins to rattle. Initial results from this study are presented and discussed. Future efforts will continue to explore the rattle occurrence in windows of residential houses exposed to sonic booms.

Impact of electric fields on honey bees

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bindokas, V.P.

1985-01-01

Biological effects in honey bee colonies under a 765-kV, 60-Hz transmission line (electric (E) field = 7 kV/m) were confirmed using controlled dosimetry and treatment reversal to replicate findings within the same season. Hives in the same environment but shielded from E field are normal, suggesting effects are caused by interaction of E field with the hive. Bees flying through the ambient E field are not demonstrably affected. Different thresholds and severity of effects were found in colonies exposed to 7, 5.5, 4.1, 1.8, and 0.65 to 0.85 kV/m at incremental distances from the line. Most colonies exposed at 7more » kV/m failed in 8 weeks and failed to overwinter at greater than or equal to4.1 kV/m. Data suggest the limit of a biological effects corridor lies between 15 and 27 m (4.1 and 1.8 kV/m) beyond the outer phase of the transmission line. Mechanisms to explain colony disturbance fall into two categories, direct perception of enhanced in-hive E fields, and perception of shock from induced currents. The same effects induced in colonies with total-hive E-field exposure can be reproduced with shock or E-field exposure of worker bees in extended hive entranceways (= porches). Full-scale experiments demonstrate bee exposure to E fields including 100 kV/m under moisture-free conditions within a non-conductive porch causes no detectable effect on colony behavior. Exposure of bees on a conductive (e.g. wet) substrate produces been disturbance, increased mortality, abnormal propolization, and possible impairment of colony growth. Thresholds for effects caused by step-potential-induced currents are: 275-350 nA - disturbance of single bees; 600 nA - onset of abnormal propolization; and 900 nA - sting.« less

Motion coherence and direction discrimination in healthy aging.

PubMed

Pilz, Karin S; Miller, Louisa; Agnew, Hannah C

2017-01-01

Perceptual functions change with age, particularly motion perception. With regard to healthy aging, previous studies mostly measured motion coherence thresholds for coarse motion direction discrimination along cardinal axes of motion. Here, we investigated age-related changes in the ability to discriminate between small angular differences in motion directions, which allows for a more specific assessment of age-related decline and its underlying mechanisms. We first assessed older (>60 years) and younger (<30 years) participants' ability to discriminate coarse horizontal (left/right) and vertical (up/down) motion at 100% coherence and a stimulus duration of 400 ms. In a second step, we determined participants' motion coherence thresholds for vertical and horizontal coarse motion direction discrimination. In a third step, we used the individually determined motion coherence thresholds and tested fine motion direction discrimination for motion clockwise away from horizontal and vertical motion. Older adults performed as well as younger adults for discriminating motion away from vertical. Surprisingly, performance for discriminating motion away from horizontal was strongly decreased. Further analyses, however, showed a relationship between motion coherence thresholds for horizontal coarse motion direction discrimination and fine motion direction discrimination performance in older adults. In a control experiment, using motion coherence above threshold for all conditions, the difference in performance for horizontal and vertical fine motion direction discrimination for older adults disappeared. These results clearly contradict the notion of an overall age-related decline in motion perception, and, most importantly, highlight the importance of taking into account individual differences when assessing age-related changes in perceptual functions.

Accuracy of cochlear implant recipients in speech reception in the presence of background music.

PubMed

Gfeller, Kate; Turner, Christopher; Oleson, Jacob; Kliethermes, Stephanie; Driscoll, Virginia

2012-12-01

This study examined speech recognition abilities of cochlear implant (CI) recipients in the spectrally complex listening condition of 3 contrasting types of background music, and compared performance based upon listener groups: CI recipients using conventional long-electrode devices, Hybrid CI recipients (acoustic plus electric stimulation), and normal-hearing adults. We tested 154 long-electrode CI recipients using varied devices and strategies, 21 Hybrid CI recipients, and 49 normal-hearing adults on closed-set recognition of spondees presented in 3 contrasting forms of background music (piano solo, large symphony orchestra, vocal solo with small combo accompaniment) in an adaptive test. Signal-to-noise ratio thresholds for speech in music were examined in relation to measures of speech recognition in background noise and multitalker babble, pitch perception, and music experience. The signal-to-noise ratio thresholds for speech in music varied as a function of category of background music, group membership (long-electrode, Hybrid, normal-hearing), and age. The thresholds for speech in background music were significantly correlated with measures of pitch perception and thresholds for speech in background noise; auditory status was an important predictor. Evidence suggests that speech reception thresholds in background music change as a function of listener age (with more advanced age being detrimental), structural characteristics of different types of music, and hearing status (residual hearing). These findings have implications for everyday listening conditions such as communicating in social or commercial situations in which there is background music.

Accuracy of Cochlear Implant Recipients on Speech Reception in Background Music

PubMed Central

Gfeller, Kate; Turner, Christopher; Oleson, Jacob; Kliethermes, Stephanie; Driscoll, Virginia

2012-01-01

Objectives This study (a) examined speech recognition abilities of cochlear implant (CI) recipients in the spectrally complex listening condition of three contrasting types of background music, and (b) compared performance based upon listener groups: CI recipients using conventional long-electrode (LE) devices, Hybrid CI recipients (acoustic plus electric stimulation), and normal-hearing (NH) adults. Methods We tested 154 LE CI recipients using varied devices and strategies, 21 Hybrid CI recipients, and 49 NH adults on closed-set recognition of spondees presented in three contrasting forms of background music (piano solo, large symphony orchestra, vocal solo with small combo accompaniment) in an adaptive test. Outcomes Signal-to-noise thresholds for speech in music (SRTM) were examined in relation to measures of speech recognition in background noise and multi-talker babble, pitch perception, and music experience. Results SRTM thresholds varied as a function of category of background music, group membership (LE, Hybrid, NH), and age. Thresholds for speech in background music were significantly correlated with measures of pitch perception and speech in background noise thresholds; auditory status was an important predictor. Conclusions Evidence suggests that speech reception thresholds in background music change as a function of listener age (with more advanced age being detrimental), structural characteristics of different types of music, and hearing status (residual hearing). These findings have implications for everyday listening conditions such as communicating in social or commercial situations in which there is background music. PMID:23342550

Sugar reduction in fruit nectars: Impact on consumers' sensory and hedonic perception.

PubMed

Oliveira, Denize; Galhardo, Juliana; Ares, Gastón; Cunha, Luís M; Deliza, Rosires

2018-05-01

Sugar sweetened beverages are one of the main sources of added sugar in the diet. Therefore, sugar reduction in these products could contribute to the prevention of various negative health conditions, such as obesity, diabetes and cardiovascular diseases. In this context, the present work aimed to study consumer sensory and hedonic perception towards sugar reduction in fruit nectars. Five sequential difference thresholds for added sugar in three fruit nectars (passion fruit, orange/passion fruit and orange/pomegranate) were determined based on consumer perception. In each test, difference thresholds were estimated using survival analysis based on the responses of 50 consumers to six paired-comparison tests. Each pair was composed of two samples, a control nectar and a sample that was reduced in added sugar from the control. Consumers were asked to try each of the samples in each pair and to indicate which was sweeter. Then, consumers' sensory and hedonic perception of nectar samples was evaluated for each nectar using a 9-point hedonic scale and a check-all-that-apply question. Difference thresholds were estimated in 4.20%-8.14% of the added sugar concentration of the nectars. No significant differences in overall liking were detected for fruit nectars with 20% sugar reduction. However, large heterogeneity in consumer hedonic reaction towards sugar reduction was found, which should be taken into account in the design of sugar reduction programs. Consumer hedonic reaction towards sugar reduction was product dependent. Results from the present work reinforce the idea that gradual sugar reduction in sugar sweetened beverages is a feasible strategy that could contribute to reduce the sugar intake of the population. Copyright © 2018 Elsevier Ltd. All rights reserved.

Olfactory Impact of Higher Alcohols on Red Wine Fruity Ester Aroma Expression in Model Solution.

PubMed

Cameleyre, Margaux; Lytra, Georgia; Tempere, Sophie; Barbe, Jean-Christophe

2015-11-11

This study focused on the impact of five higher alcohols on the perception of fruity aroma in red wines. Various aromatic reconstitutions were prepared, consisting of 13 ethyl esters and acetates and 5 higher alcohols, all at the average concentrations found in red wine. These aromatic reconstitutions were prepared in several matrices. Sensory analysis revealed the interesting behavior of certain compounds among the five higher alcohols following their individual addition or omission. The "olfactory threshold" of the fruity pool was evaluated in several matrices: dilute alcohol solution, dilute alcohol solution containing 3-methylbutan-1-ol or butan-1-ol individually, and dilute alcohol solution containing the mixture of five higher alcohols, blended together at various concentrations. The presence of 3-methylbutan-1-ol or butan-1-ol alone led to a significant decrease in the "olfactory threshold" of the fruity reconstitution, whereas the mixture of alcohols raised the olfactory threshold. Sensory profiles highlighted changes in the perception of fruity nuances in the presence of the mixture of higher alcohols, with specific perceptive interactions, including a relevant masking effect on fresh- and jammy-fruit notes of the fruity mixture in both dilute alcohol solution and dearomatized red wine matrices. When either 3-methylbutan-1-ol or butan-1-ol was added to the fruity reconstitution in dilute alcohol solution, an enhancement of butyric notes was reported with 3-methylbutan-1-ol and fresh- and jammy-fruit with butan-1-ol. This study, the first to focus on the impact of higher alcohols on fruity aromatic expression, revealed that these compounds participate, both quantitatively and qualitatively, in masking fruity aroma perception in a model fruity wine mixture.

A consumer-based approach to salt reduction: Case study with bread.

PubMed

Antúnez, Lucía; Giménez, Ana; Ares, Gastón

2016-12-01

In recent years high sodium intake has raised growing concern worldwide. A widespread reduction of salt concentration in processed foods has been claimed as one of the most effective strategies to achieve a short-term impact on global health. However, one of the major challenges in reducing salt in food products is its potential negative impact on consumer perception. For this reason, gradual salt reduction has been recommended. In this context, the aim of the present work was to present a consumer-based approach to salt reduction, using bread as case study. Two consumer studies with a total of 303 consumers were carried out. In the first study, four sequential difference thresholds were determined through paired-comparison tests, starting at a salt concentration of 2%. In the second study, 99 consumers performed a two-bite evaluation of their sensory and hedonic perception of five bread samples: a control bread containing 2% salt and four samples with reduced salt content according to the difference thresholds determined in the first study. Survival analysis was used to determine average difference thresholds, which ranged from 9.4% to 14.3% of the salt concentration of the control bread. Results showed that salt concentration significantly influenced consumer overall liking of the bread samples. However, large heterogeneity was found in consumer hedonic reaction towards salt reduction: two groups of consumers with different preference and hedonic sensitivity to salt reduction were found. Results from the present work confirm that cumulative series of small salt reductions may be a feasible strategy for reducing the sodium content of bread without affecting consumer hedonic perception and stress the importance of considering consumer perception in the design of gradual salt reduction programmes. Copyright © 2016 Elsevier Ltd. All rights reserved.

NEURAL ORGANIZATION OF SENSORY INFORMATIONS FOR TASTE,

DTIC Science & Technology

TASTE , ELECTROPHYSIOLOGY), (*NERVES, *TONGUE), NERVE CELLS, NERVE IMPULSES, PHYSIOLOGY, NERVOUS SYSTEM, STIMULATION(PHYSIOLOGY), NERVE FIBERS, RATS...HAMSTERS, STIMULATION(PHYSIOLOGY), PERCEPTION, COOLING, BEHAVIOR, PSYCHOPHYSIOLOGY, TEMPERATURE, THRESHOLDS(PHYSIOLOGY), CHEMORECEPTORS , STATISTICAL ANALYSIS, JAPAN

An Evaluation of Psychophysical Models of Auditory Change Perception

PubMed Central

Micheyl, Christophe; Kaernbach, Christian; Demany, Laurent

2009-01-01

In many psychophysical experiments, the participant's task is to detect small changes along a given stimulus dimension, or to identify the direction (e.g., upward vs. downward) of such changes. The results of these experiments are traditionally analyzed using a constant-variance Gaussian (CVG) model or a high-threshold (HT) model. Here, the authors demonstrate that for changes along three basic sound dimensions (frequency, intensity, and amplitude-modulation rate), such models cannot account for the observed relationship between detection thresholds and direction-identification thresholds. It is shown that two alternative models can account for this relationship. One of them is based on the idea of sensory “quanta”; the other assumes that small changes are detected on the basis of Poisson processes with low means. The predictions of these two models are then compared against receiver operating characteristics (ROCs) for the detection of changes in sound intensity. It is concluded that human listeners' perception of small and unidimensional acoustic changes is better described by a discrete-state Poisson model than by the more commonly used CVG model or by the less favored HT and quantum models. PMID:18954215

The perception of verticality in lunar and Martian gravity conditions.

PubMed

de Winkel, Ksander N; Clément, Gilles; Groen, Eric L; Werkhoven, Peter J

2012-10-31

Although the mechanisms of neural adaptation to weightlessness and re-adaptation to Earth-gravity have received a lot of attention since the first human space flight, there is as yet little knowledge about how spatial orientation is affected by partial gravity, such as lunar gravity of 0.16 g or Martian gravity of 0.38 g. Up to now twelve astronauts have spent a cumulated time of approximately 80 h on the lunar surface, but no psychophysical experiments were conducted to investigate their perception of verticality. We investigated how the subjective vertical (SV) was affected by reduced gravity levels during the first European Parabolic Flight Campaign of Partial Gravity. In normal and hypergravity, subjects accurately aligned their SV with the gravitational vertical. However, when gravity was below a certain threshold, subjects aligned their SV with their body longitudinal axis. The value of the threshold varied considerably between subjects, ranging from 0.03 to 0.57 g. Despite the small number of subjects, there was a significant positive correlation of the threshold with subject age, which calls for further investigation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Perceptual color difference metric including a CSF based on the perception threshold

NASA Astrophysics Data System (ADS)

Rosselli, Vincent; Larabi, Mohamed-Chaker; Fernandez-Maloigne, Christine

2008-01-01

The study of the Human Visual System (HVS) is very interesting to quantify the quality of a picture, to predict which information will be perceived on it, to apply adapted tools ... The Contrast Sensitivity Function (CSF) is one of the major ways to integrate the HVS properties into an imaging system. It characterizes the sensitivity of the visual system to spatial and temporal frequencies and predicts the behavior for the three channels. Common constructions of the CSF have been performed by estimating the detection threshold beyond which it is possible to perceive a stimulus. In this work, we developed a novel approach for spatio-chromatic construction based on matching experiments to estimate the perception threshold. It consists in matching the contrast of a test stimulus with that of a reference one. The obtained results are quite different in comparison with the standard approaches as the chromatic CSFs have band-pass behavior and not low pass. The obtained model has been integrated in a perceptual color difference metric inspired by the s-CIELAB. The metric is then evaluated with both objective and subjective procedures.

Input-output relation and energy efficiency in the neuron with different spike threshold dynamics.

PubMed

Yi, Guo-Sheng; Wang, Jiang; Tsang, Kai-Ming; Wei, Xi-Le; Deng, Bin

2015-01-01

Neuron encodes and transmits information through generating sequences of output spikes, which is a high energy-consuming process. The spike is initiated when membrane depolarization reaches a threshold voltage. In many neurons, threshold is dynamic and depends on the rate of membrane depolarization (dV/dt) preceding a spike. Identifying the metabolic energy involved in neural coding and their relationship to threshold dynamic is critical to understanding neuronal function and evolution. Here, we use a modified Morris-Lecar model to investigate neuronal input-output property and energy efficiency associated with different spike threshold dynamics. We find that the neurons with dynamic threshold sensitive to dV/dt generate discontinuous frequency-current curve and type II phase response curve (PRC) through Hopf bifurcation, and weak noise could prohibit spiking when bifurcation just occurs. The threshold that is insensitive to dV/dt, instead, results in a continuous frequency-current curve, a type I PRC and a saddle-node on invariant circle bifurcation, and simultaneously weak noise cannot inhibit spiking. It is also shown that the bifurcation, frequency-current curve and PRC type associated with different threshold dynamics arise from the distinct subthreshold interactions of membrane currents. Further, we observe that the energy consumption of the neuron is related to its firing characteristics. The depolarization of spike threshold improves neuronal energy efficiency by reducing the overlap of Na(+) and K(+) currents during an action potential. The high energy efficiency is achieved at more depolarized spike threshold and high stimulus current. These results provide a fundamental biophysical connection that links spike threshold dynamics, input-output relation, energetics and spike initiation, which could contribute to uncover neural encoding mechanism.

Input-output relation and energy efficiency in the neuron with different spike threshold dynamics

PubMed Central

Yi, Guo-Sheng; Wang, Jiang; Tsang, Kai-Ming; Wei, Xi-Le; Deng, Bin

2015-01-01

Neuron encodes and transmits information through generating sequences of output spikes, which is a high energy-consuming process. The spike is initiated when membrane depolarization reaches a threshold voltage. In many neurons, threshold is dynamic and depends on the rate of membrane depolarization (dV/dt) preceding a spike. Identifying the metabolic energy involved in neural coding and their relationship to threshold dynamic is critical to understanding neuronal function and evolution. Here, we use a modified Morris-Lecar model to investigate neuronal input-output property and energy efficiency associated with different spike threshold dynamics. We find that the neurons with dynamic threshold sensitive to dV/dt generate discontinuous frequency-current curve and type II phase response curve (PRC) through Hopf bifurcation, and weak noise could prohibit spiking when bifurcation just occurs. The threshold that is insensitive to dV/dt, instead, results in a continuous frequency-current curve, a type I PRC and a saddle-node on invariant circle bifurcation, and simultaneously weak noise cannot inhibit spiking. It is also shown that the bifurcation, frequency-current curve and PRC type associated with different threshold dynamics arise from the distinct subthreshold interactions of membrane currents. Further, we observe that the energy consumption of the neuron is related to its firing characteristics. The depolarization of spike threshold improves neuronal energy efficiency by reducing the overlap of Na+ and K+ currents during an action potential. The high energy efficiency is achieved at more depolarized spike threshold and high stimulus current. These results provide a fundamental biophysical connection that links spike threshold dynamics, input-output relation, energetics and spike initiation, which could contribute to uncover neural encoding mechanism. PMID:26074810

Subliminal stimuli modulate somatosensory perception rhythmically and provide evidence for discrete perception.

PubMed

Baumgarten, Thomas J; Königs, Sara; Schnitzler, Alfons; Lange, Joachim

2017-03-09

Despite being experienced as continuous, there is an ongoing debate if perception is an intrinsically discrete process, with incoming sensory information treated as a succession of single perceptual cycles. Here, we provide causal evidence that somatosensory perception is composed of discrete perceptual cycles. We used in humans an electrotactile temporal discrimination task preceded by a subliminal (i.e., below perceptual threshold) stimulus. Although not consciously perceived, subliminal stimuli are known to elicit neuronal activity in early sensory areas and modulate the phase of ongoing neuronal oscillations. We hypothesized that the subliminal stimulus indirectly, but systematically modulates the ongoing oscillatory phase in S1, thereby rhythmically shaping perception. The present results confirm that, without being consciously perceived, the subliminal stimulus critically influenced perception in the discrimination task. Importantly, perception was modulated rhythmically, in cycles corresponding to the beta-band (13-18 Hz). This can be compellingly explained by a model of discrete perceptual cycles.

Reduced Discrimination in the Tritanopic Confusion Line for Congenital Color Deficiency Adults.

PubMed

Costa, Marcelo F; Goulart, Paulo R K; Barboni, Mirella T S; Ventura, Dora F

2016-01-01

In congenital color blindness the red-green discrimination is impaired resulting in an increased confusion between those colors with yellow. Our post-receptoral physiological mechanisms are organized in two pathways for color perception, a red-green (protanopic and deuteranopic) and a blue-yellow (tritanopic). We argue that the discrimination losses in the yellow area in congenital color vision deficiency subjects could generate a subtle loss of discriminability in the tritanopic channel considering discrepancies with yellow perception. We measured color discrimination thresholds for blue and yellow of tritanopic channel in congenital color deficiency subjects. Chromaticity thresholds were measured around a white background (0.1977 u', 0.4689 v' in the CIE 1976) consisting of a blue-white and white-yellow thresholds in a tritanopic color confusion line of 21 congenital colorblindness subjects (mean age = 27.7; SD = 5.6 years; 14 deuteranomalous and 7 protanomalous) and of 82 (mean age = 25.1; SD = 3.7 years) normal color vision subjects. Significant increase in the whole tritanopic axis was found for both deuteranomalous and protanomalous subjects compared to controls for the blue-white (F 2,100 = 18.80; p < 0.0001) and white-yellow (F 2,100 = 22.10; p < 0.0001) thresholds. A Principal Component Analysis (PCA) found a weighting toward to the yellow thresholds induced by deuteranomalous subjects. In conclusion, the discrimination in the tritanopic color confusion axis is significantly reduced in congenital color vision deficiency compared to normal subjects. Since yellow discrimination was impaired the balance of the blue-yellow channels is impaired justifying the increased thresholds found for blue-white discrimination. The weighting toward the yellow region of the color space with the deuteranomalous contributing to that perceptual distortion is discussed in terms of physiological mechanisms.

Abnormal pain perception in patients with Multiple System Atrophy.

PubMed

Ory-Magne, F; Pellaprat, J; Harroch, E; Galitzsky, M; Rousseau, V; Pavy-Le Traon, A; Rascol, O; Gerdelat, A; Brefel-Courbon, C

2018-03-01

Patients with Parkinson's disease or Multiple System Atrophy frequently experience painful sensations. The few studies investigating pain mechanisms in Multiple System Atrophy patients have reported contradictory results. In our study, we compared pain thresholds in Multiple System Atrophy and Parkinson's disease patients and healthy controls and evaluated the effect of l-DOPA on pain thresholds. We assessed subjective and objective pain thresholds (using a thermotest and RIII reflex), and pain tolerance in OFF and ON conditions, clinical pain, motor and psychological evaluation. Pain was reported in 78.6% of Multiple System Atrophy patients and in 37.5% of Parkinson's disease patients. In the OFF condition, subjective and objective pain thresholds were significantly lower in Multiple System Atrophy patients than in healthy controls (43.8 °C ± 1.3 vs 45.7 °C ± 0.8; p = 0.0005 and 7.4 mA ± 3.8 vs 13.7 mA ± 2.8; p = 0.002, respectively). They were also significantly reduced in Multiple System Atrophy compared to Parkinson's disease patients. No significant difference was found in pain tolerance for the 3 groups and in the effect of l-DOPA on pain thresholds in Multiple System Atrophy and Parkinson's disease patients. In the ON condition, pain tolerance tended to be reduced in Multiple System Atrophy versus Parkinson's disease patients (p = 0.05). Multiple System Atrophy patients had an increase in pain perception compared to Parkinson's disease patients and healthy controls. The l-DOPA effect was similar for pain thresholds in Multiple System Atrophy and Parkinson's disease patients, but tended to worsen pain tolerance in Multiple System Atrophy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vibrotactile perception thresholds at the sole of the foot: effects of contact force and probe indentation.

PubMed

Gu, Cheng; Griffin, Michael J

2012-05-01

When using vibrotactile thresholds to investigate neuropathy in the fingers, the indentation of a vibrating probe, and the force applied to a static surround around a vibrating probe, affect thresholds. This study was designed to investigate the effects on vibrotactile perception thresholds at the sole of the foot of probe indentation (i.e. height of a vibrating probe relative to a static surround) and the force applied to the static surround. Thresholds at 20 Hz (expected to be mediated by the NP I channel) and at 160 Hz (expected to be mediated by the Pacinian channel) were obtained at the hallux (i.e. greater toe) and the ball of the foot on 14 healthy subjects. In one condition, the height of the vibrating probe was varied to 0, 1, 2, 3, and 4 mm above a static surround with 4-N force applied to the surround. In a second condition, the force applied to the surround was varied to 1, 2, 3, 4, 5, and 6 N while using a probe height of 1mm. Thresholds at 20 Hz decreased with increasing probe height from 0 to 1 mm but showed no significant variation between 2, 3, and 4mm at either the hallux or the ball of the foot. Thresholds at 160 Hz decreased with increasing probe height from 0 to 4 mm at both the hallux and the ball of the foot. Thresholds at 20 Hz obtained with 1-N surround force were higher than thresholds obtained with 2 N, but there was no significant difference with surround forces from 2 to 6 N at either the hallux or the ball of the foot. Thresholds at 160 Hz were unaffected by variations in surround force at the ball of the foot but tended to decrease with increasing force at the hallux. It is concluded that a vibrating probe flush with a static surround, and a surround force in the range 2-4 N, are appropriate when measuring vibrotactile thresholds at the hallux and the ball of the foot with a 6-mm diameter contactor and a 2-mm gap to the static surround. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

Development and validation of the University of Washington Clinical Assessment of Music Perception test.

PubMed

Kang, Robert; Nimmons, Grace Liu; Drennan, Ward; Longnion, Jeff; Ruffin, Chad; Nie, Kaibao; Won, Jong Ho; Worman, Tina; Yueh, Bevan; Rubinstein, Jay

2009-08-01

Assessment of cochlear implant outcomes centers around speech discrimination. Despite dramatic improvements in speech perception, music perception remains a challenge for most cochlear implant users. No standardized test exists to quantify music perception in a clinically practical manner. This study presents the University of Washington Clinical Assessment of Music Perception (CAMP) test as a reliable and valid music perception test for English-speaking, adult cochlear implant users. Forty-two cochlear implant subjects were recruited from the University of Washington Medical Center cochlear implant program and referred by two implant manufacturers. Ten normal-hearing volunteers were drawn from the University of Washington Medical Center and associated campuses. A computer-driven, self-administered test was developed to examine three specific aspects of music perception: pitch direction discrimination, melody recognition, and timbre recognition. The pitch subtest used an adaptive procedure to determine just-noticeable differences for complex tone pitch direction discrimination within the range of 1 to 12 semitones. The melody and timbre subtests assessed recognition of 12 commonly known melodies played with complex tones in an isochronous manner and eight musical instruments playing an identical five-note sequence, respectively. Testing was repeated for cochlear implant subjects to evaluate test-retest reliability. Normal-hearing volunteers were also tested to demonstrate differences in performance in the two populations. For cochlear implant subjects, pitch direction discrimination just-noticeable differences ranged from 1 to 8.0 semitones (Mean = 3.0, SD = 2.3). Melody and timbre recognition ranged from 0 to 94.4% correct (mean = 25.1, SD = 22.2) and 20.8 to 87.5% (mean = 45.3, SD = 16.2), respectively. Each subtest significantly correlated at least moderately with both Consonant-Nucleus-Consonant (CNC) word recognition scores and spondee recognition thresholds in steady state noise and two-talker babble. Intraclass coefficients demonstrating test-retest correlations for pitch, melody, and timbre were 0.85, 0.92, and 0.69, respectively. Normal-hearing volunteers had a mean pitch direction discrimination threshold of 1.0 semitone, the smallest interval tested, and mean melody and timbre recognition scores of 87.5 and 94.2%, respectively. The CAMP test discriminates a wide range of music perceptual ability in cochlear implant users. Moderate correlations were seen between music test results and both Consonant-Nucleus-Consonant word recognition scores and spondee recognition thresholds in background noise. Test-retest reliability was moderate to strong. The CAMP test provides a reliable and valid metric for a clinically practical, standardized evaluation of music perception in adult cochlear implant users.

Pain and sex hormones: a review of current understanding.

PubMed

Maurer, Adrian J; Lissounov, Alexei; Knezevic, Ivana; Candido, Kenneth D; Knezevic, Nebojsa Nick

2016-01-01

Multiple epidemiologic studies have demonstrated an increased prevalence for women in several chronic pain disorders. Clinical and experimental investigations have consistently demonstrated sex-specific differences in pain sensitivity and pain threshold. Even though the underlying mechanisms responsible for these differences have not yet been elucidated, the logical possibility of gonadal hormone influence on nociceptive processing has garnered recent attention. In this review, we evaluated the complex literature regarding gonadal hormones and their influence on pain perception. We reviewed the numerous functions of gonadal hormones, discussed the influence of these hormones on several common chronic pain syndromes (migraine, tension and cluster headaches, fibromyalgia, temporomandibular syndrome, rheumatoid arthritis and back pain, among others), and have attempted to draw conclusions from the available data.

A transformation-aware perceptual image metric

NASA Astrophysics Data System (ADS)

Kellnhofer, Petr; Ritschel, Tobias; Myszkowski, Karol; Seidel, Hans-Peter

2015-03-01

Predicting human visual perception has several applications such as compression, rendering, editing and retargeting. Current approaches however, ignore the fact that the human visual system compensates for geometric transformations, e. g., we see that an image and a rotated copy are identical. Instead, they will report a large, false-positive difference. At the same time, if the transformations become too strong or too spatially incoherent, comparing two images indeed gets increasingly difficult. Between these two extrema, we propose a system to quantify the effect of transformations, not only on the perception of image differences, but also on saliency. To this end, we first fit local homographies to a given optical flow field and then convert this field into a field of elementary transformations such as translation, rotation, scaling, and perspective. We conduct a perceptual experiment quantifying the increase of difficulty when compensating for elementary transformations. Transformation entropy is proposed as a novel measure of complexity in a flow field. This representation is then used for applications, such as comparison of non-aligned images, where transformations cause threshold elevation, and detection of salient transformations.

Eleven Colors That Are Almost Never Confused

NASA Astrophysics Data System (ADS)

Boynton, Robert M.

1989-08-01

1.1. Three functions of color vision. Setting aside the complex psychological effects of color, related to esthetics, fashion, and mood, three relatively basic functions of color vision, which can be examined scientifically, are discernable. (1) With the eye in a given state of adaptation, color vision allows the perception of signals that otherwise would be below threshold, and therefore lost to perception. Evidence for this comes from a variety of two-color threshold experiments. (2) Visible contours can be maintained by color differences alone, regardless of the relative radiances of the two parts of the field whose junction defines the border. For achromatic vision, contour disappears at the isoluminant point. (3) Color specifies what seems to be an absolute property of a surface, one that enhances its recognizability and allows a clearer separation and classification of non-contiguous elements in the visual field.

How Much Gravity Is Needed to Establish the Perceptual Upright?

PubMed Central

Harris, Laurence R.; Herpers, Rainer; Hofhammer, Thomas; Jenkin, Michael

2014-01-01

Might the gravity levels found on other planets and on the moon be sufficient to provide an adequate perception of upright for astronauts? Can the amount of gravity required be predicted from the physiological threshold for linear acceleration? The perception of upright is determined not only by gravity but also visual information when available and assumptions about the orientation of the body. Here, we used a human centrifuge to simulate gravity levels from zero to earth gravity along the long-axis of the body and measured observers' perception of upright using the Oriented Character Recognition Test (OCHART) with and without visual cues arranged to indicate a direction of gravity that differed from the body's long axis. This procedure allowed us to assess the relative contribution of the added gravity in determining the perceptual upright. Control experiments off the centrifuge allowed us to measure the relative contributions of normal gravity, vision, and body orientation for each participant. We found that the influence of 1 g in determining the perceptual upright did not depend on whether the acceleration was created by lying on the centrifuge or by normal gravity. The 50% threshold for centrifuge-simulated gravity's ability to influence the perceptual upright was at around 0.15 g, close to the level of moon gravity but much higher than the threshold for detecting linear acceleration along the long axis of the body. This observation may partially explain the instability of moonwalkers but is good news for future missions to Mars. PMID:25184481

Slant Perception Under Stereomicroscopy.

PubMed

Horvath, Samantha; Macdonald, Kori; Galeotti, John; Klatzky, Roberta L

2017-11-01

Objective These studies used threshold and slant-matching tasks to assess and quantitatively measure human perception of 3-D planar images viewed through a stereomicroscope. The results are intended for use in developing augmented-reality surgical aids. Background Substantial research demonstrates that slant perception is performed with high accuracy from monocular and binocular cues, but less research concerns the effects of magnification. Viewing through a microscope affects the utility of monocular and stereo slant cues, but its impact is as yet unknown. Method Participants performed in a threshold slant-detection task and matched the slant of a tool to a surface. Different stimuli and monocular versus binocular viewing conditions were implemented to isolate stereo cues alone, stereo with perspective cues, accommodation cue only, and cues intrinsic to optical-coherence-tomography images. Results At magnification of 5x, slant thresholds with stimuli providing stereo cues approximated those reported for direct viewing, about 12°. Most participants (75%) who passed a stereoacuity pretest could match a tool to the slant of a surface viewed with stereo at 5x magnification, with mean compressive error of about 20% for optimized surfaces. Slant matching to optical coherence tomography images of the cornea viewed under the microscope was also demonstrated. Conclusion Despite the distortions and cue loss introduced by viewing under the stereomicroscope, most participants were able to detect and interact with slanted surfaces. Application The experiments demonstrated sensitivity to surface slant that supports the development of augmented-reality systems to aid microscope-aided surgery.

Global motion perception in children with amblyopia as a function of spatial and temporal stimulus parameters.

PubMed

Meier, Kimberly; Sum, Brian; Giaschi, Deborah

2016-10-01

Global motion sensitivity in typically developing children depends on the spatial (Δx) and temporal (Δt) displacement parameters of the motion stimulus. Specifically, sensitivity for small Δx values matures at a later age, suggesting it may be the most vulnerable to damage by amblyopia. To explore this possibility, we compared motion coherence thresholds of children with amblyopia (7-14years old) to age-matched controls. Three Δx values were used with two Δt values, yielding six conditions covering a range of speeds (0.3-30deg/s). We predicted children with amblyopia would show normal coherence thresholds for the same parameters on which 5-year-olds previously demonstrated mature performance, and elevated coherence thresholds for parameters on which 5-year-olds demonstrated immaturities. Consistent with this, we found that children with amblyopia showed deficits with amblyopic eye viewing compared to controls for small and medium Δx values, regardless of Δt value. The fellow eye showed similar results at the smaller Δt. These results confirm that global motion perception in children with amblyopia is particularly deficient at the finer spatial scales that typically mature later in development. An additional implication is that carefully designed stimuli that are adequately sensitive must be used to assess global motion function in developmental disorders. Stimulus parameters for which performance matures early in life may not reveal global motion perception deficits. Copyright © 2016 Elsevier Ltd. All rights reserved.

How much gravity is needed to establish the perceptual upright?

PubMed

Harris, Laurence R; Herpers, Rainer; Hofhammer, Thomas; Jenkin, Michael

2014-01-01

Might the gravity levels found on other planets and on the moon be sufficient to provide an adequate perception of upright for astronauts? Can the amount of gravity required be predicted from the physiological threshold for linear acceleration? The perception of upright is determined not only by gravity but also visual information when available and assumptions about the orientation of the body. Here, we used a human centrifuge to simulate gravity levels from zero to earth gravity along the long-axis of the body and measured observers' perception of upright using the Oriented Character Recognition Test (OCHART) with and without visual cues arranged to indicate a direction of gravity that differed from the body's long axis. This procedure allowed us to assess the relative contribution of the added gravity in determining the perceptual upright. Control experiments off the centrifuge allowed us to measure the relative contributions of normal gravity, vision, and body orientation for each participant. We found that the influence of 1 g in determining the perceptual upright did not depend on whether the acceleration was created by lying on the centrifuge or by normal gravity. The 50% threshold for centrifuge-simulated gravity's ability to influence the perceptual upright was at around 0.15 g, close to the level of moon gravity but much higher than the threshold for detecting linear acceleration along the long axis of the body. This observation may partially explain the instability of moonwalkers but is good news for future missions to Mars.

Temporal Fine Structure Processing, Pitch, and Speech Perception in Adult Cochlear Implant Recipients.

PubMed

Dincer D'Alessandro, Hilal; Ballantyne, Deborah; Boyle, Patrick J; De Seta, Elio; DeVincentiis, Marco; Mancini, Patrizia

2017-11-30

The aim of the study was to investigate the link between temporal fine structure (TFS) processing, pitch, and speech perception performance in adult cochlear implant (CI) recipients, including bimodal listeners who may benefit better low-frequency (LF) temporal coding in the contralateral ear. The study participants were 43 adult CI recipients (23 unilateral, 6 bilateral, and 14 bimodal listeners). Two new LF pitch perception tests-harmonic intonation (HI) and disharmonic intonation (DI)-were used to evaluate TFS sensitivity. HI and DI were designed to estimate a difference limen for discrimination of tone changes based on harmonic or inharmonic pitch glides. Speech perception was assessed using the newly developed Italian Sentence Test with Adaptive Randomized Roving level (STARR) test where sentences relevant to everyday contexts were presented at low, medium, and high levels in a fluctuating background noise to estimate a speech reception threshold (SRT). Although TFS and STARR performances in the majority of CI recipients were much poorer than those of hearing people reported in the literature, a considerable intersubject variability was observed. For CI listeners, median just noticeable differences were 27.0 and 147.0 Hz for HI and DI, respectively. HI outcomes were significantly better than those for DI. Median STARR score was 14.8 dB. Better performers with speech reception thresholds less than 20 dB had a median score of 8.6 dB. A significant effect of age was observed for both HI/DI tests, suggesting that TFS sensitivity tended to worsen with increasing age. CI pure-tone thresholds and duration of profound deafness were significantly correlated with STARR performance. Bimodal users showed significantly better TFS and STARR performance for bimodal listening than for their CI-only condition. Median bimodal gains were 33.0 Hz for the HI test and 95.0 Hz for the DI test. DI outcomes in bimodal users revealed a significant correlation with unaided hearing thresholds for octave frequencies lower than 1000 Hz. Median STARR scores were 17.3 versus 8.1 dB for CI only and bimodal listening, respectively. STARR performance was significantly correlated with HI findings for CI listeners and with those of DI for bimodal listeners. LF pitch perception was found to be abnormal in the majority of adult CI recipients, confirming poor TFS processing of CIs. Similarly, the STARR findings reflected a common performance deterioration with the HI/DI tests, suggesting the cause probably being a lack of access to TFS information. Contralateral hearing aid users obtained a remarkable bimodal benefit for all tests. Such results highlighted the importance of TFS cues for challenging speech perception and the relevance to everyday listening conditions. HI/DI and STARR tests show promise for gaining insights into how TFS and speech perception are being limited and may guide the customization of CI program parameters and support the fine tuning of bimodal listening.

The characteristics of vibrotactile perception threshold among shipyard workers in a tropical environment.

PubMed

Tamrin, Shamsul Bahri Mohd; Jamalohdin, Mohd Nazri; Ng, Yee Guan; Maeda, Setsuo; Ali, Nurul Asyiqin Mohd

2012-01-01

The objectives of this study are to determine the prevalence of hand-arm vibration syndrome (HAVS) and the characteristics of the vibrotactile perception threshold (VPT) among users of hand-held vibrating tools working in a tropical environment. A cross sectional study was done among 47 shipyard workers using instruments and a questionnaire to determine HAVS related symptoms. The vibration acceleration magnitude was determined using a Human Vibration Meter (Maestro). A P8 Pallesthesiometer (EMSON-MAT, Poland) was used to determine the VPT of index and little finger at frequencies of 31.5 Hz and 125 Hz. The mean reference threshold shift was determined from the reference threshold shift derived from the VPT value. The results show a moderate prevalence of HAVS (49%) among the shipyard workers. They were exposed to the same high intensity level of HAVS (mean = 4.19 ± 1.94 m/s(2)) from the use of vibrating hand-held tools. The VPT values were found to be higher for both fingers and both frequencies (index, 31.5 Hz = 110.91 ± 7.36 dB, 125 Hz = 117.0 ± 10.25 dB; little, 31.5 Hz = 110.70 ± 6.75 dB, 125 Hz = 117.71 ± 10.25 dB) compared to the normal healthy population with a mean threshold shift of between 9.20 to 10.61 decibels. The frequency of 31.5 Hz had a higher percentage of positive mean reference threshold shift (index finger=93.6%, little finger=100%) compared to 125 Hz (index finger=85.1%, little finger=78.7%). In conclusion, the prevalence of HAVS was lower than those working in a cold environment; however, all workers had a higher mean VPT value compared to the normal population with all those reported as having HAVS showing a positive mean reference threshold shift of VPT value.

Hydrodynamic sensory threshold in harbour seals (Phoca vitulina) for artificial flatfish breathing currents.

PubMed

Niesterok, Benedikt; Dehnhardt, Guido; Hanke, Wolf

2017-07-01

Harbour seals have the ability to detect benthic fish such as flatfish using the water currents these fish emit through their gills (breathing currents). We investigated the sensory threshold in harbour seals for this specific hydrodynamic stimulus under conditions which are realistic for seals hunting in the wild. We used an experimental platform where an artificial breathing current was emitted through one of eight different nozzles. Two seals were trained to search for the active nozzle. Each experimental session consisted of eight test trials of a particular stimulus intensity and 16 supra-threshold trials of high stimulus intensity. Test trials were conducted with the animals blindfolded. To determine the threshold, a series of breathing currents differing in intensity was used. For each intensity, three sessions were run. The threshold in terms of maximum water velocity within the breathing current was 4.2 cm s -1 for one seal and 3.7 cm s -1 for the other. We measured background flow velocities from 1.8 to 3.4 cm s -1 Typical swimming speeds for both animals were around 0.5 m s -1 Swimming speed differed between successful and unsuccessful trials. It appears that swimming speed is restricted for the successful detection of a breathing current close to the threshold. Our study is the first to assess a sensory threshold of the vibrissal system for a moving harbour seal under near-natural conditions. Furthermore, this threshold was defined for a natural type of stimulus differing from classical dipole stimuli which have been widely used in threshold determination so far. © 2017. Published by The Company of Biologists Ltd.

A Theoretical and Experimental Analysis of the Outside World Perception Process

NASA Technical Reports Server (NTRS)

Wewerinke, P. H.

1978-01-01

The outside scene is often an important source of information for manual control tasks. Important examples of these are car driving and aircraft control. This paper deals with modelling this visual scene perception process on the basis of linear perspective geometry and the relative motion cues. Model predictions utilizing psychophysical threshold data from base-line experiments and literature of a variety of visual approach tasks are compared with experimental data. Both the performance and workload results illustrate that the model provides a meaningful description of the outside world perception process, with a useful predictive capability.

Round Window Application of an Active Middle Ear Implant: A Comparison With Hearing Aid Usage in Japan.

PubMed

Iwasaki, Satoshi; Usami, Shin-Ichi; Takahashi, Haruo; Kanda, Yukihiko; Tono, Tetsuya; Doi, Katsumi; Kumakawa, Kozo; Gyo, Kiyofumi; Naito, Yasushi; Kanzaki, Sho; Yamanaka, Noboru; Kaga, Kimitaka

2017-07-01

To report on the safety and efficacy of an investigational active middle ear implant (AMEI) in Japan, and to compare results to preoperative results with a hearing aid. Prospective study conducted in Japan in which 23 Japanese-speaking adults suffering from conductive or mixed hearing loss received a VIBRANT SOUNDBRIDGE with implantation at the round window. Postoperative thresholds, speech perception results (word recognition scores, speech reception thresholds, signal-to-noise ratio [SNR]), and quality of life questionnaires at 20 weeks were compared with preoperative results with all patients receiving the same, best available hearing aid (HA). Statistically significant improvements in postoperative AMEI-aided thresholds (1, 2, 4, and 8 kHz) and on the speech reception thresholds and word recognition scores tests, compared with preoperative HA-aided results, were observed. On the SNR, the subjects' mean values showed statistically significant improvement, with -5.7 dB SNR for the AMEI-aided mean and -2.1 dB SNR for the preoperative HA-assisted mean. The APHAB quality of life questionnaire also showed statistically significant improvement with the AMEI. Results with the AMEI applied to the round window exceeded those of the best available hearing aid in speech perception as well as quality of life questionnaires. There were minimal adverse events or changes to patients' residual hearing.

Aging deteriorated perception of urge-to-cough without changing cough reflex threshold to citric acid in female never-smokers.

PubMed

Ebihara, Satoru; Ebihara, Takae; Kanezaki, Masashi; Gui, Peijun; Yamasaki, Miyako; Arai, Hiroyuki; Kohzuki, Masahiro

2011-06-28

The effect of aging on the cognitive aspect of cough has not been studied yet. The purpose of this study is to investigate the aging effect on the perception of urge-to-cough in healthy individuals. Fourteen young, female, healthy never-smokers were recruited via public postings. Twelve elderly female healthy never-smokers were recruited from a nursing home residence. The cough reflex threshold and the urge-to-cough were evaluated by inhalation of citric acid. The cough reflex sensitivities were defined as the lowest concentration of citric acid that elicited two or more coughs (C2) and five or more coughs (C5). The urge-to-cough was evaluated using a modified the Borg scale. There was no significant difference in the cough reflex threshold to citric acid between young and elderly subjects. The urge-to-cough scores at the concentration of C2 and C5 were significantly smaller in the elderly than young subjects. The urge-to-cough log-log slope in elderly subjects (0.73 ± 0.71 point · L/g) was significantly gentler than those of young subjects (1.35 ± 0.53 point · L/g, p < 0.01). There were no significant differences in the urge-to-cough threshold estimated between young and elderly subjects. The cough reflex threshold did not differ between young and elderly subjects whereas cognition of urge-to-cough was significantly decreased in elderly subjects in female never-smokers. Objective monitoring of cough might be important in the elderly people.

Algorithm for improving psychophysical threshold estimates by detecting sustained inattention in experiments using PEST.

PubMed

Rinderknecht, Mike D; Ranzani, Raffaele; Popp, Werner L; Lambercy, Olivier; Gassert, Roger

2018-05-10

Psychophysical procedures are applied in various fields to assess sensory thresholds. During experiments, sampled psychometric functions are usually assumed to be stationary. However, perception can be altered, for example by loss of attention to the presentation of stimuli, leading to biased data, which results in poor threshold estimates. The few existing approaches attempting to identify non-stationarities either detect only whether there was a change in perception, or are not suitable for experiments with a relatively small number of trials (e.g., [Formula: see text] 300). We present a method to detect inattention periods on a trial-by-trial basis with the aim of improving threshold estimates in psychophysical experiments using the adaptive sampling procedure Parameter Estimation by Sequential Testing (PEST). The performance of the algorithm was evaluated in computer simulations modeling inattention, and tested in a behavioral experiment on proprioceptive difference threshold assessment in 20 stroke patients, a population where attention deficits are likely to be present. Simulations showed that estimation errors could be reduced by up to 77% for inattentive subjects, even in sequences with less than 100 trials. In the behavioral data, inattention was detected in 14% of assessments, and applying the proposed algorithm resulted in reduced test-retest variability in 73% of these corrected assessments pairs. The novel algorithm complements existing approaches and, besides being applicable post hoc, could also be used online to prevent collection of biased data. This could have important implications in assessment practice by shortening experiments and improving estimates, especially for clinical settings.

Biophysical mechanism of spike threshold dependence on the rate of rise of the membrane potential by sodium channel inactivation or subthreshold axonal potassium current

PubMed Central

Wester, Jason C.

2013-01-01

Spike threshold filters incoming inputs and thus gates activity flow through neuronal networks. Threshold is variable, and in many types of neurons there is a relationship between the threshold voltage and the rate of rise of the membrane potential (dVm/dt) leading to the spike. In primary sensory cortex this relationship enhances the sensitivity of neurons to a particular stimulus feature. While Na+ channel inactivation may contribute to this relationship, recent evidence indicates that K+ currents located in the spike initiation zone are crucial. Here we used a simple Hodgkin-Huxley biophysical model to systematically investigate the role of K+ and Na+ current parameters (activation voltages and kinetics) in regulating spike threshold as a function of dVm/dt. Threshold was determined empirically and not estimated from the shape of the Vm prior to a spike. This allowed us to investigate intrinsic currents and values of gating variables at the precise voltage threshold. We found that Na+ inactivation is sufficient to produce the relationship provided it occurs at hyperpolarized voltages combined with slow kinetics. Alternatively, hyperpolarization of the K+ current activation voltage, even in the absence of Na+ inactivation, is also sufficient to produce the relationship. This hyperpolarized shift of K+ activation allows an outward current prior to spike initiation to antagonize the Na+ inward current such that it becomes self-sustaining at a more depolarized voltage. Our simulations demonstrate parameter constraints on Na+ inactivation and the biophysical mechanism by which an outward current regulates spike threshold as a function of dVm/dt. PMID:23344915

The perception of probability.

PubMed

Gallistel, C R; Krishan, Monika; Liu, Ye; Miller, Reilly; Latham, Peter E

2014-01-01

We present a computational model to explain the results from experiments in which subjects estimate the hidden probability parameter of a stepwise nonstationary Bernoulli process outcome by outcome. The model captures the following results qualitatively and quantitatively, with only 2 free parameters: (a) Subjects do not update their estimate after each outcome; they step from one estimate to another at irregular intervals. (b) The joint distribution of step widths and heights cannot be explained on the assumption that a threshold amount of change must be exceeded in order for them to indicate a change in their perception. (c) The mapping of observed probability to the median perceived probability is the identity function over the full range of probabilities. (d) Precision (how close estimates are to the best possible estimate) is good and constant over the full range. (e) Subjects quickly detect substantial changes in the hidden probability parameter. (f) The perceived probability sometimes changes dramatically from one observation to the next. (g) Subjects sometimes have second thoughts about a previous change perception, after observing further outcomes. (h) The frequency with which they perceive changes moves in the direction of the true frequency over sessions. (Explaining this finding requires 2 additional parametric assumptions.) The model treats the perception of the current probability as a by-product of the construction of a compact encoding of the experienced sequence in terms of its change points. It illustrates the why and the how of intermittent Bayesian belief updating and retrospective revision in simple perception. It suggests a reinterpretation of findings in the recent literature on the neurobiology of decision making. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Disrupted Self-Perception in People With Chronic Low Back Pain. Further Evaluation of the Fremantle Back Awareness Questionnaire.

PubMed

Wand, Benedict Martin; Catley, Mark Jon; Rabey, Martin Ian; O'Sullivan, Peter Bruce; O'Connell, Neil Edward; Smith, Anne Julia

2016-09-01

Several lines of evidence suggest that body perception is altered in people with chronic back pain. Maladaptive perceptual awareness of the back might contribute to the pain experience as well as serve as a target for treatment. The Fremantle Back Awareness Questionnaire (FreBAQ) is a simple questionnaire recently developed to assess back-specific altered self-perception. The aims of this study were to present the outcomes of a comprehensive evaluation of the questionnaire's psychometric properties and explore the potential relationships between body perception, nociceptive sensitivity, distress, and beliefs about back pain and the contribution these factors might play in explaining pain and disability. Two hundred fifty-one people with chronic back pain completed the questionnaire as well as a battery of clinical tests. The Rasch model was used to explore the questionnaires' psychometric properties and correlation and multiple linear regression analyses were used to explore the relationship between altered body perception and clinical status. The FreBAQ appears unidimensional with no redundant items, has minimal ceiling and floor effects, acceptable internal consistency, was functional on the category rating scale, and was not biased by demographic or clinical variables. FreBAQ scores were correlated with sensitivity, distress, and beliefs and were uniquely associated with pain and disability. Several lines of evidence suggest that body perception might be disturbed in people with chronic low back pain, possibly contributing to the condition and offering a potential target for treatment. The FreBAQ was developed as a quick and simple way of measuring back-specific body perception in people with chronic low back pain. The questionnaire appears to be a psychometrically sound way of assessing altered self-perception. The level of altered self-perception is positively correlated with pain intensity and disability as well as showing associations with psychological distress, pain catastrophization, fear avoidance beliefs, and lumbar pressure pain threshold. In this sample, it appears that altered self-perception might be a more important determinant of clinical severity than psychological distress, pain catastrophization, fear avoidance beliefs, or lumbar pressure pain threshold. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Very low threshold-current temperature sensitivity in constricted double-heterojunction AlGaAs lasers

NASA Technical Reports Server (NTRS)

Botez, D.; Connolly, J. C.; Gilbert, D. B.; Ettenberg, M.

1981-01-01

The temperature dependence of threshold currents in constricted double-heterojunction diode lasers with strong lateral mode confinement is found to be significantly milder than for other types of lasers. The threshold-current relative variations with ambient temperature are typically two to three times less than for other devices of CW-operation capability. Over the interval 10-70 C the threshold currents fit the empirical exponential law exp/(T2-T1)/T0/ with T0 values in the 240-375 C range in pulsed operation, and in the 200-310 C range in CW operation. The external differential quantum efficiency and the mode far-field pattern near threshold are virtually invariant with temperature. The possible causes of high-T0 behavior are analyzed, and a new phenomenon - temperature-dependent current focusing - is presented to explain the results.

Inhibitory effect of cervical trachea and chest wall vibrations on cough reflex sensitivity and perception of urge-to-cough in healthy male never-smokers

PubMed Central

2013-01-01

Background Non-pharmacological options for symptomatic management of cough are desired. Although chest wall mechanical vibration is known to ameliorate cough reflex sensitivity, the effect of mechanical vibrations on perceptions of urge-to-cough has not been studied. Therefore, we investigated the effect of mechanical vibration of cervical trachea, chest wall and femoral muscle on cough reflex sensitivity, perceptions of urge-to-cough as well as dyspnea. Methods Twenty-four healthy male never-smokers were investigated for cough reflex sensitivity, perceptions of the urge-to-cough and dyspnea with or without mechanical vibration. Cough reflex sensitivity and urge-to-cough were evaluated by the inhalation of citric acid. The perception of dyspnea was evaluated by Borg scores during applications of external inspiratory resistive loads. Mechanical vibration was applied by placing a vibrating tuning fork on the skin surface of cervical trachea, chest wall and femoral muscle. Results Cervical trachea vibration significantly increased cough reflex threshold, as expressed by the lowest concentration of citric acid that elicited five or more coughs (C5), and urge-to-cough threshold, as expressed by the lowest concentration of citric acid that elicited urge-to-cough (Cu), but did not significantly affect dypnea sensation during inspiratory resistive loading. On the other hand, the chest wall vibration not only significantly increased C5 and Cu but also significantly ameliorated the load-response curve of dyspnea sensation. Conclusions Both cervical and trachea vibrations significantly inhibited cough reflex sensitivity and perception of urge-to-cough. These vibration techniques might be options for symptomatic cough management. PMID:24088411

Influence of emission threshold of explosive emission cathodes on current waveform in foilless diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, P.; Liu, G. Z.; Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024

The emission threshold of explosive emission cathodes (EECs) is an important factor for beam quality. It can affect the explosive emission delay time, the plasma expansion process on the cathode surface, and even the current amplitude when the current is not fully space-charge-limited. This paper researches the influence of the emission threshold of an annular EEC on the current waveform in a foilless diode when the current is measured by a Rogowski coil. The particle-in-cell simulation which is performed under some tolerable and necessary simplifications shows that the long explosive emission delay time of high-threshold cathodes may leave an apparentmore » peak of displacement current on the rise edge of the current waveform, and this will occur only when the electron emission starts after this peak. The experimental researches, which are performed under a diode voltage of 1 MV and a repetitive frequency of 20 Hz, demonstrate that the graphite cathode has a lower emission threshold and a longer lifetime than the stainless steel cathode according to the variation of the peak of displacement current on the rise edge of the current waveform.« less

Temperature dependence of threshold current in GaAs/AlGaAs quantum well lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blood, P.; Colak, S.; Kucharska, A.I.

1988-02-22

We have calculated the threshold current and its temperature (T) dependence in the range 200--400 K for AlGaAs quantum well lasers with 25-A-wide GaAs wells using a model which includes lifetime broadening of the transitions and broadening of the density of states function by fluctuations in the well width. The threshold current varies approximately linearly with T and the principal effect of broadening is to increase the threshold current causing a reduction in the fractional change of current with temperature. The apparent value of the parameter T/sub 0/ is increased to approx. =400 K, compared with approx. =320 K withoutmore » broadening. The calculations are compared with experimental data.« less

Binaural beats and frequency-coding.

PubMed

Fritze, W; Köhler, W

1986-01-01

Binaural beats were studied before and during a situation of temporary threshold shift, and no frequency shift could be found. In contrast, subjective binaural frequency comparison revealed a distinct shift. These findings demonstrate the two known modes of perception.

Action Video Games Improve Direction Discrimination of Parafoveal Translational Global Motion but Not Reaction Times.

PubMed

Pavan, Andrea; Boyce, Matthew; Ghin, Filippo

2016-10-01

Playing action video games enhances visual motion perception. However, there is psychophysical evidence that action video games do not improve motion sensitivity for translational global moving patterns presented in fovea. This study investigates global motion perception in action video game players and compares their performance to that of non-action video game players and non-video game players. Stimuli were random dot kinematograms presented in the parafovea. Observers discriminated the motion direction of a target random dot kinematogram presented in one of the four visual quadrants. Action video game players showed lower motion coherence thresholds than the other groups. However, when the task was performed at threshold, we did not find differences between groups in terms of distributions of reaction times. These results suggest that action video games improve visual motion sensitivity in the near periphery of the visual field, rather than speed response. © The Author(s) 2016.

The economics of motion perception and invariants of visual sensitivity.

PubMed

Gepshtein, Sergei; Tyukin, Ivan; Kubovy, Michael

2007-06-21

Neural systems face the challenge of optimizing their performance with limited resources, just as economic systems do. Here, we use tools of neoclassical economic theory to explore how a frugal visual system should use a limited number of neurons to optimize perception of motion. The theory prescribes that vision should allocate its resources to different conditions of stimulation according to the degree of balance between measurement uncertainties and stimulus uncertainties. We find that human vision approximately follows the optimal prescription. The equilibrium theory explains why human visual sensitivity is distributed the way it is and why qualitatively different regimes of apparent motion are observed at different speeds. The theory offers a new normative framework for understanding the mechanisms of visual sensitivity at the threshold of visibility and above the threshold and predicts large-scale changes in visual sensitivity in response to changes in the statistics of stimulation and system goals.

Stochastic Accumulation by Cortical Columns May Explain the Scalar Property of Multistable Perception

NASA Astrophysics Data System (ADS)

Cao, Robin; Braun, Jochen; Mattia, Maurizio

2014-08-01

The timing of certain mental events is thought to reflect random walks performed by underlying neural dynamics. One class of such events—stochastic reversals of multistable perceptions—exhibits a unique scalar property: even though timing densities vary widely, higher moments stay in particular proportions to the mean. We show that stochastic accumulation of activity in a finite number of idealized cortical columns—realizing a generalized Ehrenfest urn model—may explain these observations. Modeling stochastic reversals as the first-passage time of a threshold number of active columns, we obtain higher moments of the first-passage time density. We derive analytical expressions for noninteracting columns and generalize the results to interacting columns in simulations. The scalar property of multistable perception is reproduced by a dynamic regime with a fixed, low threshold, in which the activation of a few additional columns suffices for a reversal.

Selective weighting of cutaneous receptor feedback and associated balance impairments following short duration space flight.

PubMed

Strzalkowski, Nicholas D J; Lowrey, Catherine R; Perry, Stephen D; Williams, David R; Wood, Scott J; Bent, Leah R

2015-04-10

The present study investigated the perception of low frequency (3 Hz) vibration on the foot sole and its relationship to standing balance following short duration space flight in nine astronauts. Both 3 Hz vibration perception threshold (VPT) and standing balance measures increased on landing day compared to pre-flight. Contrary to our hypothesis, a positive linear relationship between these measures was not observed; however astronauts with the most sensitive skin (lowest 3 Hz VPT) were found to have the largest sway on landing day. While the change in foot sole sensitivity does not appear to directly relate to standing balance control, an exploratory strategy may be employed by astronauts whose threshold to pressure information is lower. Understanding sensory adaptations and balance control has implications to improve balance control strategies following space flight and in sensory impaired populations on earth. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Pain perception and cardiovascular system response among athletes playing contact sports.

PubMed

Leźnicka, Katarzyna; Pawlak, Matthias; Białecka, Monika; Safranow, Krzysztof; Cięszczyk, Paweł

2017-01-01

The aim of this study was to determine whether the contact sports change the perception of pain as assessed by the cold pressor test (CPT), and if the test induces the same reaction of the cardiovascular system in contact athletes and non-athletes. The study involved 321 healthy men; 140 contact athletes and 181 students of the University of Szczecin (control). Pain threshold and pain tolerance were evaluated using CPT. Cardiovascular measurements were made during CPT. The contact athletes showed a much higher tolerance to pain than the control group (median time 120 vs. 94 s, respectively, p = 0.0002). The thresholds of pain in both groups did not differ significantly between the groups. Systolic blood pressure measured before and during the test in all three measurements was statistically significantly higher in athletes compared with the control group. Heart rate and diastolic blood pressure did not differ significantly between the studied groups.

Attentional limits on the perception and memory of visual information.

PubMed

Palmer, J

1990-05-01

Attentional limits on perception and memory were measured by the decline in performance with increasing numbers of objects in a display. Multiple objects were presented to Ss who discriminated visual attributes. In a representative condition, 4 lines were briefly presented followed by a single line in 1 of the same locations. Ss were required to judge if the single line in the 2nd display was longer or shorter than the line in the corresponding location of the 1st display. The length difference threshold was calculated as a function of the number of objects. The difference thresholds doubled when the number of objects was increased from 1 to 4. This effect was generalized in several ways, and nonattentional explanations were ruled out. Further analyses showed that the attentional processes must share information from at least 4 objects and can be described by a simple model.

Visual perception system and method for a humanoid robot

NASA Technical Reports Server (NTRS)

Chelian, Suhas E. (Inventor); Linn, Douglas Martin (Inventor); Wampler, II, Charles W. (Inventor); Bridgwater, Lyndon (Inventor); Wells, James W. (Inventor); Mc Kay, Neil David (Inventor)

2012-01-01

A robotic system includes a humanoid robot with robotic joints each moveable using an actuator(s), and a distributed controller for controlling the movement of each of the robotic joints. The controller includes a visual perception module (VPM) for visually identifying and tracking an object in the field of view of the robot under threshold lighting conditions. The VPM includes optical devices for collecting an image of the object, a positional extraction device, and a host machine having an algorithm for processing the image and positional information. The algorithm visually identifies and tracks the object, and automatically adapts an exposure time of the optical devices to prevent feature data loss of the image under the threshold lighting conditions. A method of identifying and tracking the object includes collecting the image, extracting positional information of the object, and automatically adapting the exposure time to thereby prevent feature data loss of the image.

Specific conditions of distress in the dental situation.

PubMed

Hentschel, U; Allander, L; Winholt, A S

1977-01-01

The general feeling of distress in the dental situation has been studied in 60 female dental patients and correlated to the following variables: Experimentally evaluated sensitivity to pain, self-rating and the dentist's rating of sensitivity to pain, the pain-threshold value in the teeth, the need of local anesthesia, extraversion-introversion, neuroticism, and some percept-genetic psychological measures of adaptive behavior. The subjects have also answered a questionnaire for grading their distress in regard to different aspects of the treatment-situation, which were combined into eight groups using factor analysis and then correlated to the general distress. The variables having a significant relation to distress in the dental situation were: the dentist's rating of the patient's sensitivity, the need of anesthesia, four groups of treatment-components and two of the percept-genetic measures. There was also a certain relation to the pain threshold in the teeth.

The influence of stripe width on the threshold current of double-heterojunction lasers

NASA Technical Reports Server (NTRS)

Ladany, I.

1977-01-01

Experimental measurements of the threshold current of oxide-isolated stripe laser as a function of stripe width and p-layer resistivity are presented. A calculation of the influence of carrier outdiffusion has been made, including the effect of current leakage beyond the stripe edges. The calculated threshold increase is in substantial agreement with experiment for stripe widths down to about 10 microns. The data also yield an effective diffusion length of about 7 microns for the lasers studied. Deviations between experimental and calculated thresholds occurring at stripe widths of 4-6 microns are represented by an empirical curve which is compared with previously published calculations of threshold gain.

Subliminal stimuli modulate somatosensory perception rhythmically and provide evidence for discrete perception

PubMed Central

Baumgarten, Thomas J.; Königs, Sara; Schnitzler, Alfons; Lange, Joachim

2017-01-01

Despite being experienced as continuous, there is an ongoing debate if perception is an intrinsically discrete process, with incoming sensory information treated as a succession of single perceptual cycles. Here, we provide causal evidence that somatosensory perception is composed of discrete perceptual cycles. We used in humans an electrotactile temporal discrimination task preceded by a subliminal (i.e., below perceptual threshold) stimulus. Although not consciously perceived, subliminal stimuli are known to elicit neuronal activity in early sensory areas and modulate the phase of ongoing neuronal oscillations. We hypothesized that the subliminal stimulus indirectly, but systematically modulates the ongoing oscillatory phase in S1, thereby rhythmically shaping perception. The present results confirm that, without being consciously perceived, the subliminal stimulus critically influenced perception in the discrimination task. Importantly, perception was modulated rhythmically, in cycles corresponding to the beta-band (13–18 Hz). This can be compellingly explained by a model of discrete perceptual cycles. PMID:28276493

Visual Aversive Learning Compromises Sensory Discrimination.

PubMed

Shalev, Lee; Paz, Rony; Avidan, Galia

2018-03-14

Aversive learning is thought to modulate perceptual thresholds, which can lead to overgeneralization. However, it remains undetermined whether this modulation is domain specific or a general effect. Moreover, despite the unique role of the visual modality in human perception, it is unclear whether this aspect of aversive learning exists in this modality. The current study was designed to examine the effect of visual aversive outcomes on the perception of basic visual and auditory features. We tested the ability of healthy participants, both males and females, to discriminate between neutral stimuli, before and after visual learning. In each experiment, neutral stimuli were associated with aversive images in an experimental group and with neutral images in a control group. Participants demonstrated a deterioration in discrimination (higher discrimination thresholds) only after aversive learning. This deterioration was measured for both auditory (tone frequency) and visual (orientation and contrast) features. The effect was replicated in five different experiments and lasted for at least 24 h. fMRI neural responses and pupil size were also measured during learning. We showed an increase in neural activations in the anterior cingulate cortex, insula, and amygdala during aversive compared with neutral learning. Interestingly, the early visual cortex showed increased brain activity during aversive compared with neutral context trials, with identical visual information. Our findings imply the existence of a central multimodal mechanism, which modulates early perceptual properties, following exposure to negative situations. Such a mechanism could contribute to abnormal responses that underlie anxiety states, even in new and safe environments. SIGNIFICANCE STATEMENT Using a visual aversive-learning paradigm, we found deteriorated discrimination abilities for visual and auditory stimuli that were associated with visual aversive stimuli. We showed increased neural activations in the anterior cingulate cortex, insula, and amygdala during aversive learning, compared with neutral learning. Importantly, similar findings were also evident in the early visual cortex during trials with aversive/neutral context, but with identical visual information. The demonstration of this phenomenon in the visual modality is important, as it provides support to the notion that aversive learning can influence perception via a central mechanism, independent of input modality. Given the dominance of the visual system in human perception, our findings hold relevance to daily life, as well as imply a potential etiology for anxiety disorders. Copyright © 2018 the authors 0270-6474/18/382766-14$15.00/0.

Acid sensitization of esophageal mucosal afferents: implication for symptom perception in patients across the gastroesophageal reflux disease spectrum.

PubMed

Szczesniak, Michal Marcin; Fuentealba, Sergio Enrique; Cook, Ian J

2013-01-01

Sensitization of esophageal chemoreceptors, either directly by intermittent acid exposure or indirectly through esophagitis-associated inflammatory mediators, is likely to be the mechanism underlying the perception of heartburn. To compare basal esophageal sensitivity with electrical stimulation and acid, and to compare the degree of acid-induced sensitization in controls and in patient groups across the entire spectrum of gastroesophageal reflux disease: erosive oesophagitis (EO), nonerosive reflux disease (NERD), and functional heartburn (FH). Esophageal sensory and pain thresholds to electrical stimulation were measured before, 30, and 60 minutes after an intraesophageal infusion of saline or HCl. Patients received a 30-minute infusion of 0.15 M HCl and controls were randomized to receive either HCl (n = 11) or saline (n = 10). After electrical sensory threshold testing, participants received another 30-minute infusion of HCl to determine whether sensitivity to acid is increased by prior acid exposure All patient groups had higher basal sensory thresholds than healthy controls (controls, 13 ± 1.4 mA; FH, 20 ± 5.1 mA; NERD, 21 ± 5.1 mA; EO, 23 ± 5.4 mA; P < 0.05). Acute esophageal acid exposure reduced sensory thresholds to electrical stimulation in FH and NERD patients (P < 0.05). The level of acid sensitivity during the first HCl infusion was comparable between all patient groups and controls. The secondary infusion caused increased discomfort in all participants (P < 0.01). This acid-induced sensitization to HCl was significantly elevated in the patient groups ( P < 0.05). (1) Esophageal acid infusion sensitizes it to subsequent electrical and chemical stimulation. (2) The acid-related sensitization is greater in gastroesophageal reflux disease than in controls and may influence in part symptom perception in this population. (3) Acid-related sensitization within the gastroesophageal reflux disease population is not dependant on mucosal inflammation.

Investigation of two methods to quantify noise in digital images based on the perception of the human eye

NASA Astrophysics Data System (ADS)

Kleinmann, Johanna; Wueller, Dietmar

2007-01-01

Since the signal to noise measuring method as standardized in the normative part of ISO 15739:2002(E)1 does not quantify noise in a way that matches the perception of the human eye, two alternative methods have been investigated which may be appropriate to quantify the noise perception in a physiological manner: - the model of visual noise measurement proposed by Hung et al2 (as described in the informative annex of ISO 15739:20021) which tries to simulate the process of human vision by using the opponent space and contrast sensitivity functions and uses the CIEL*u*v*1976 colour space for the determination of a so called visual noise value. - The S-CIELab model and CIEDE2000 colour difference proposed by Fairchild et al 3 which simulates human vision approximately the same way as Hung et al2 but uses an image comparison afterwards based on CIEDE2000. With a psychophysical experiment based on just noticeable difference (JND), threshold images could be defined, with which the two approaches mentioned above were tested. The assumption is that if the method is valid, the different threshold images should get the same 'noise value'. The visual noise measurement model results in similar visual noise values for all the threshold images. The method is reliable to quantify at least the JND for noise in uniform areas of digital images. While the visual noise measurement model can only evaluate uniform colour patches in images, the S-CIELab model can be used on images with spatial content as well. The S-CIELab model also results in similar colour difference values for the set of threshold images, but with some limitations: for images which contain spatial structures besides the noise, the colour difference varies depending on the contrast of the spatial content.

Decreased visual detection during subliminal stimulation.

PubMed

Bareither, Isabelle; Villringer, Arno; Busch, Niko A

2014-10-17

What is the perceptual fate of invisible stimuli-are they processed at all and does their processing have consequences for the perception of other stimuli? As has been shown previously in the somatosensory system, even stimuli that are too weak to be consciously detected can influence our perception: Subliminal stimulation impairs perception of near-threshold stimuli and causes a functional deactivation in the somatosensory cortex. In a recent study, we showed that subliminal visual stimuli lead to similar responses, indicated by an increase in alpha-band power as measured with electroencephalography (EEG). In the current study, we investigated whether a behavioral inhibitory mechanism also exists within the visual system. We tested the detection of peripheral visual target stimuli under three different conditions: Target stimuli were presented alone or embedded in a concurrent train of subliminal stimuli either at the same location as the target or in the opposite hemifield. Subliminal stimuli were invisible due to their low contrast, not due to a masking procedure. We demonstrate that target detection was impaired by the subliminal stimuli, but only when they were presented at the same location as the target. This finding indicates that subliminal, low-intensity stimuli induce a similar inhibitory effect in the visual system as has been observed in the somatosensory system. In line with previous reports, we propose that the function underlying this effect is the inhibition of spurious noise by the visual system. © 2014 ARVO.

Extra-high voltage transmission lines: mechanisms of biological effects on honeybees. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenberg, B.; Bindokas, V.

1985-08-01

The authors confirmed that bee exposure to E fields, including 100 kV/m, under the dry conditions cause no detectable effect on colony behavior. If, however, exposure occurs when moisture is present, or if bees are on a conductive surface, they become visibly disturbed, mortality is increased, abnormal propolization occurs, and colony development may be impaired. It seems plausible that bees on conductive surfaces within a hive under a 765-kV/m transmission line can perceive shocks from body currents induced by enhanced intra-hive E fields. Hives exposed under a 765-kV/m transmission line to an ambient E field of 7 kV/m have internalmore » step-potential-induced currents and interchamber chort-circuit currents which range from one-half to several microamperes. Total hive currents can exceed 100 ..mu..A. Thus, induced hive currents exceed the empirical sting threshold by up to a factor of 100 and the E-field-induced body current by up to a factor of 1000. The degree of disturbance which could be produced by these intra-hive currents will eclipse that produced by perception of E-field-induced body currents. The authors therefore attribute the disturbance of colonies under a transmission line primarily to electric shock from induced hive currents. 10 refs., 51 figs., 18 tabs. (DT)« less

The effect of deep and slow breathing on pain perception, autonomic activity, and mood processing--an experimental study.

PubMed

Busch, Volker; Magerl, Walter; Kern, Uwe; Haas, Joachim; Hajak, Göran; Eichhammer, Peter

2012-02-01

Deep and slow breathing (DSB) techniques, as a component of various relaxation techniques, have been reported as complementary approaches in the treatment of chronic pain syndromes, but the relevance of relaxation for alleviating pain during a breathing intervention was not evaluated so far. In order to disentangle the effects of relaxation and respiration, we investigated two different DSB techniques at the same respiration rates and depths on pain perception, autonomic activity, and mood in 16 healthy subjects. In the attentive DSB intervention, subjects were asked to breathe guided by a respiratory feedback task requiring a high degree of concentration and constant attention. In the relaxing DSB intervention, the subjects relaxed during the breathing training. The skin conductance levels, indicating sympathetic tone, were measured during the breathing maneuvers. Thermal detection and pain thresholds for cold and hot stimuli and profile of mood states were examined before and after the breathing sessions. The mean detection and pain thresholds showed a significant increase resulting from the relaxing DSB, whereas no significant changes of these thresholds were found associated with the attentive DSB. The mean skin conductance levels indicating sympathetic activity decreased significantly during the relaxing DSB intervention but not during the attentive DSB. Both breathing interventions showed similar reductions in negative feelings (tension, anger, and depression). Our results suggest that the way of breathing decisively influences autonomic and pain processing, thereby identifying DSB in concert with relaxation as the essential feature in the modulation of sympathetic arousal and pain perception. Wiley Periodicals, Inc.

Decreased sensitivity to thermal pain in rats bred for high anxiety-related behaviour is attenuated by citalopram or diazepam treatment.

PubMed

Jochum, Thomas; Boettger, Michael Karl; Wigger, Alexandra; Beiderbeck, Daniela; Neumann, Inga D; Landgraf, Rainer; Sauer, Heinrich; Bär, Karl-Jürgen

2007-10-01

Complex interactions between pain perception, anxiety and depressive symptoms have repeatedly been described. However, pathophysiological or biochemical mechanisms underlying the alterations of pain perception in patients suffering from anxiety or depression still remain a matter of debate. Thus, we aimed to perform an investigation on pain perception in an animal model of extremes in anxiety-related behaviour, which might provide a tool for future studies. Here, thermal pain thresholds were obtained from rats with a genetic predisposition to high anxiety-related behaviour (HAB), including signs of comorbid depression-like behaviour and from controls (low-anxiety rats (LAB); cross-bred HAB and LAB rats; Wistar rats). Furthermore, the effect of eight-week antidepressive treatment using citalopram and of short-term anxiolytic treatment with diazepam on pain-related behaviour was assessed. Simultaneously, anxiety-related behaviour was monitored. At baseline, HAB animals showed 35% higher thresholds for thermal pain than controls. These were normalized to control levels after eight weeks of continuous citalopram treatment paralleled by a reduction of anxiety-related behaviour, but also acutely after diazepam administration. Overall, thermal pain thresholds in HAB animals are shifted in a similar fashion as seen in patients suffering from major depressive disorder. Antidepressive, as well as anxiolytic treatments, attenuated these differences. As the relative importance of the factors anxiety and depression cannot be derived from this study with certainty, extending these investigations to additional animal models might represent a valuable tool for future investigations concerning the interrelations between anxiety, depression, and pain at a molecular level.

5-HT modulation of pain perception in humans.

PubMed

Martin, Sarah L; Power, Andrea; Boyle, Yvonne; Anderson, Ian M; Silverdale, Monty A; Jones, Anthony K P

2017-10-01

Although there is clear evidence for the serotonergic regulation of descending control of pain in animals, little direct evidence exists in humans. The majority of our knowledge comes from the use of serotonin (5-HT)-modulating antidepressants as analgesics in the clinical management of chronic pain. Here, we have used an acute tryptophan depletion (ATD) to manipulate 5-HT function and examine its effects of ATD on heat pain threshold and tolerance, attentional manipulation of nociceptive processing and mood in human volunteers. Fifteen healthy participants received both ATD and balanced amino acid (BAL) drinks on two separate sessions in a double-blind cross-over design. Pain threshold and tolerance were determined 4 h post-drink via a heat thermode. Additional attention, distraction and temperature discrimination paradigms were completed using a laser-induced heat pain stimulus. Mood was assessed prior and throughout each session. Our investigation reported that the ATD lowered plasma TRP levels by 65.05 ± 7.29% and significantly reduced pain threshold and tolerance in response to the heat thermode. There was a direct correlation between the reduction in total plasma TRP levels and reduction in thermode temperature. In contrast, ATD showed no effect on laser-induced pain nor significant impact of the distraction-induced analgesia on pain perception but did reduce performance of the painful temperature discrimination task. Importantly, all findings were independent of any effects of ATD on mood. As far as we are aware, it is the first demonstration of 5-HT effects on pain perception which are not confounded by mood changes.

[Effect of transparent yellow and orange colored contact lenses on color discrimination in the yellow color range].

PubMed

Schürer, M; Walter, A; Brünner, H; Langenbucher, A

2015-08-01

Colored transparent filters cause a change in color perception and have an impact on the perceptible amount of different colors and especially on the ability to discriminate between them. Yellow or orange tinted contact lenses worn to enhance contrast vision by reducing or blocking short wavelengths also have an effect on color perception. The impact of the yellow and orange tinted contact lenses Wöhlk SPORT CONTRAST on color discrimination was investigated with the Erlangen colour measurement system in a study with 14 and 16 subjects, respectively. In relation to a yellow reference color located at u' = 0.2487/v' = 0.5433, measurements of color discrimination thresholds were taken in up to 6 different color coordinate axes. Based on these thresholds, color discrimination ellipses were calculated. These results are given in the Derrington, Krauskopf and Lennie (DKL) color system. Both contact lenses caused a shift of the reference color towards higher saturated colors. Color discrimination ability with the yellow and orange colored lenses was significantly enhanced along the blue-yellow axis in comparison to the reference measurements without a tinted filter. Along the red-green axis only the orange lens caused a significant reduction of color discrimination threshold distance to the reference color. Yellow and orange tinted contact lenses enhance the ability of color discrimination. If the transmission spectra and the induced changes are taken into account, these results can also be applied to other filter media, such as blue filter intraocular lenses.

Video game experience and its influence on visual attention parameters: an investigation using the framework of the Theory of Visual Attention (TVA).

PubMed

Schubert, Torsten; Finke, Kathrin; Redel, Petra; Kluckow, Steffen; Müller, Hermann; Strobach, Tilo

2015-05-01

Experts with video game experience, in contrast to non-experienced persons, are superior in multiple domains of visual attention. However, it is an open question which basic aspects of attention underlie this superiority. We approached this question using the framework of Theory of Visual Attention (TVA) with tools that allowed us to assess various parameters that are related to different visual attention aspects (e.g., perception threshold, processing speed, visual short-term memory storage capacity, top-down control, spatial distribution of attention) and that are measurable on the same experimental basis. In Experiment 1, we found advantages of video game experts in perception threshold and visual processing speed; the latter being restricted to the lower positions of the used computer display. The observed advantages were not significantly moderated by general person-related characteristics such as personality traits, sensation seeking, intelligence, social anxiety, or health status. Experiment 2 tested a potential causal link between the expert advantages and video game practice with an intervention protocol. It found no effects of action video gaming on perception threshold, visual short-term memory storage capacity, iconic memory storage, top-down control, and spatial distribution of attention after 15 days of training. However, observations of a selected improvement of processing speed at the lower positions of the computer screen after video game training and of retest effects are suggestive for limited possibilities to improve basic aspects of visual attention (TVA) with practice. Copyright © 2015 Elsevier B.V. All rights reserved.

Detection and modulation of capsaicin perception in the human oral cavity.

PubMed

Smutzer, Gregory; Jacob, Jeswin C; Tran, Joseph T; Shah, Darshan I; Gambhir, Shilpa; Devassy, Roni K; Tran, Eric B; Hoang, Brian T; McCune, Joseph F

2018-05-09

Capsaicin causes a burning or spicy sensation when this vanilloid compound comes in contact with trigeminal neurons of the tongue. This compound has low solubility in water, which presents difficulties in examining the psychophysical properties of capsaicin by standard aqueous chemosensory tests. This report describes a new approach that utilizes edible strips for delivering precise amounts of capsaicin to the human oral cavity for examining threshold and suprathreshold amounts of this irritant. When incorporated into pullulan-based edible strips, recognition thresholds for capsaicin occurred over a narrow range, with a mean value near 1 nmol. When incorporated into edible strips at suprathreshold amounts, capsaicin yielded robust intensity values that were readily measured in our subject population. Maximal capsaicin intensity was observed 20 s after strips dissolved on the tongue surface, and then decreased in intensity. Suprathreshold studies showed that complete blockage of nasal airflow diminished capsaicin perception in the oral cavity. Oral rinses with vanillin-linoleic acid emulsions decreased mean intensity values for capsaicin by approximately 75%, but only modestly affected recognition threshold values. Also, oral rinses with isointense amounts of aqueous sucrose and sucralose solutions decreased mean intensity values for capsaicin by approximately 50%. In addition, this decrease in capsaicin intensity following an oral rinse with sucrose was partially reversed by the sweet taste inhibitor lactisole. These results suggest that blockage of nasal airflow, vanillin, sucrose, and sucralose modulate capsaicin perception in the human oral cavity. The results further suggest a chemosensory link between receptor cells that detect sweet taste stimuli and trigeminal neurons that detect capsaicin. Copyright © 2018 Elsevier Inc. All rights reserved.

Does a single session of theta-burst transcranial magnetic stimulation of inferior temporal cortex affect tinnitus perception?

PubMed

Poreisz, Csaba; Paulus, Walter; Moser, Tobias; Lang, Nicolas

2009-05-29

Cortical excitability changes as well as imbalances in excitatory and inhibitory circuits play a distinct pathophysiological role in chronic tinnitus. Repetitive transcranial magnetic stimulation (rTMS) over the temporoparietal cortex was recently introduced to modulate tinnitus perception. In the current study, the effect of theta-burst stimulation (TBS), a novel rTMS paradigm was investigated in chronic tinnitus. Twenty patients with chronic tinnitus completed the study. Tinnitus severity and loudness were monitored using a tinnitus questionnaire (TQ) and a visual analogue scale (VAS) before each session. Patients received 600 pulses of continuous TBS (cTBS), intermittent TBS (iTBS) and intermediate TBS (imTBS) over left inferior temporal cortex with an intensity of 80% of the individual active or resting motor threshold. Changes in subjective tinnitus perception were measured with a numerical rating scale (NRS). TBS applied to inferior temporal cortex appeared to be safe. Although half of the patients reported a slight attenuation of tinnitus perception, group analysis resulted in no significant difference when comparing the three specific types of TBS. Converting the NRS into the VAS allowed us to compare the time-course of aftereffects. Only cTBS resulted in a significant short-lasting improvement of the symptoms. In addition there was no significant difference when comparing the responder and non-responder groups regarding their anamnestic and audiological data. The TQ score correlated significantly with the VAS, lower loudness indicating less tinnitus distress. TBS does not offer a promising outcome for patients with tinnitus in the presented study.

Perception and performance in flight simulators: The contribution of vestibular, visual, and auditory information

NASA Technical Reports Server (NTRS)

1979-01-01

The pilot's perception and performance in flight simulators is examined. The areas investigated include: vestibular stimulation, flight management and man cockpit information interfacing, and visual perception in flight simulation. The effects of higher levels of rotary acceleration on response time to constant acceleration, tracking performance, and thresholds for angular acceleration are examined. Areas of flight management examined are cockpit display of traffic information, work load, synthetic speech call outs during the landing phase of flight, perceptual factors in the use of a microwave landing system, automatic speech recognition, automation of aircraft operation, and total simulation of flight training.

Perceived Cooling Using Asymmetrically-Applied Hot and Cold Stimuli.

PubMed

Manasrah, Ahmad; Crane, Nathan; Guldiken, Rasim; Reed, Kyle B

2017-01-01

Temperature perception is a highly nonlinear phenomenon with faster rates of change being perceived at much lower thresholds than slower rates. This paper presents a method that takes advantage of this nonlinear characteristic to generate a perception of continuous cooling even though the average temperature is not changing. The method uses multiple thermal actuators so that a few are cooling quickly while the rest of the actuators are heating slowly. The slowly-heating actuators are below the perceptual threshold temperature change and hence are not perceived, while the quickly-cooling actuators are above the perceptual temperature change, hence are perceived. As a result, a feeling of decreasing temperature was elicited, when in fact, there was no net change in the temperature of the skin. Three sets of judiciously designed experiments were conducted in this study, investigating the effects of actuator sizes, forearm measurement locations, patterns of actuator layout, and various heating/cooling time cycles. Our results showed that 19 out 21 participants perceived the continuous cooling effect as hypothesized. Our research indicates that the measurement location, heating/cooling cycle times, and arrangement of the actuators affect the perception of continuous cooling.

Thresholds for activation of rabbit retinal ganglion cells with an ultrafine, extracellular microelectrode.

PubMed

Jensen, Ralph J; Rizzo, Joseph F; Ziv, Ofer R; Grumet, Andrew; Wyatt, John

2003-08-01

To determine electrical thresholds required for extracellular activation of retinal ganglion cells as part of a project to develop an epiretinal prosthesis. Retinal ganglion cells were recorded extracellularly in retinas isolated from adult New Zealand White rabbits. Electrical current pulses of 100- micro s duration were delivered to the inner surface of the retina from a 5- micro m long electrode. In about half of the cells, the point of lowest threshold was found by searching with anodal current pulses; in the other cells, cathodal current pulses were used. Threshold measurements were obtained near the cell bodies of 20 ganglion cells and near the axons of 19 ganglion cells. Both cathodal and anodal stimuli evoked a neural response in the ganglion cells that consisted of a single action potential of near-constant latency that persisted when retinal synaptic transmission was blocked with cadmium chloride. For cell bodies, but not axons, thresholds for both cathodal and anodal stimulation were dependent on the search method used to find the point of lowest threshold. With search and stimulation of matching polarity, cathodal stimuli evoked a ganglion cell response at lower currents (approximately one seventh to one tenth axonal threshold) than did anodal stimuli for both cell bodies and axons. With cathodal search and stimulation, cell body median thresholds were somewhat lower (approximately one half) than the axonal median thresholds. With anodal search and stimulation, cell body median thresholds were approximately the same as axonal median thresholds. The results suggest that cathodal stimulation should produce lower thresholds, more localized stimulation, and somewhat better selectivity for cell bodies over axons than would anodal stimulation.

Biological and Agricultural Studies on Application of Discharge Plasma and Electromagnetic Fields 5. Effects of High Electric Fields on Animals

NASA Astrophysics Data System (ADS)

Isaka, Katsuo

The biological effects of extremely low frequency electric fields on animals are reviewed with emphasis on studies of the nervous system, behavior, endocrinology, and blood chemistry. First, this paper provides a histrical overview of studies on the electric field effects initiated in Russia and the United States mainly regarding electric utility workers in high voltage substations and transmission lines. Then, the possible mechanisms of electric field effects are explained using the functions of surface electric fields and induced currents in biological objects. The real mechanisms have not yet been identified. The thresholds of electric field perception levels for rats, baboons, and humans are introduced and compared. The experimental results concerning the depression of melatonin secretion in rats exposed to electric fields are described.

Neurological abnormalities associated with CDMA exposure.

PubMed

Hocking, B; Westerman, R

2001-09-01

Dysaesthesiae of the scalp and neurological abnormality after mobile phone use have been reported previously, but the roles of the phone per se or the radiations in causing these findings have been questioned. We report finding a neurological abnormality in a patient after accidental exposure of the left side of the face to mobile phone radiation [code division multiple access (CDMA)] from a down-powered mobile phone base station antenna. He had headaches, unilateral left blurred vision and pupil constriction, unilateral altered sensation on the forehead, and abnormalities of current perception thresholds on testing the left trigeminal ophthalmic nerve. His nerve function recovered during 6 months follow-up. His exposure was 0.015-0.06 mW/cm(2) over 1-2 h. The implications regarding health effects of radiofrequency radiation are discussed.

Sound frequency affects speech emotion perception: results from congenital amusia

PubMed Central

Lolli, Sydney L.; Lewenstein, Ari D.; Basurto, Julian; Winnik, Sean; Loui, Psyche

2015-01-01

Congenital amusics, or “tone-deaf” individuals, show difficulty in perceiving and producing small pitch differences. While amusia has marked effects on music perception, its impact on speech perception is less clear. Here we test the hypothesis that individual differences in pitch perception affect judgment of emotion in speech, by applying low-pass filters to spoken statements of emotional speech. A norming study was first conducted on Mechanical Turk to ensure that the intended emotions from the Macquarie Battery for Evaluation of Prosody were reliably identifiable by US English speakers. The most reliably identified emotional speech samples were used in Experiment 1, in which subjects performed a psychophysical pitch discrimination task, and an emotion identification task under low-pass and unfiltered speech conditions. Results showed a significant correlation between pitch-discrimination threshold and emotion identification accuracy for low-pass filtered speech, with amusics (defined here as those with a pitch discrimination threshold >16 Hz) performing worse than controls. This relationship with pitch discrimination was not seen in unfiltered speech conditions. Given the dissociation between low-pass filtered and unfiltered speech conditions, we inferred that amusics may be compensating for poorer pitch perception by using speech cues that are filtered out in this manipulation. To assess this potential compensation, Experiment 2 was conducted using high-pass filtered speech samples intended to isolate non-pitch cues. No significant correlation was found between pitch discrimination and emotion identification accuracy for high-pass filtered speech. Results from these experiments suggest an influence of low frequency information in identifying emotional content of speech. PMID:26441718

The perception threshold counterpart to dynamic and static mechanical allodynia assessed using von Frey filaments in peripheral neuropathic pain patients.

PubMed

Landerholm, Åsa H; Hansson, Per T

2017-12-29

Background and aim Pain due to a usually non-painful mechanical stimulus, mechanical allodynia, is an oppressive symptom in subgroups of patients with neuropathic pain. Dynamic mechanical allodynia (DMA) is evoked by a normally innocuous light moving mechanical stimulus on the skin and static mechanical allodynia (SMA) by a sustained, normally innocuous pressure against the skin. DMA is claimed to be mediated by myelinated fibres and SMA by C-fibres. Also A-delta fibres have been implicated in the static subtype. A low intensity vertically applied stimulus of 1 second (s) is expected to activate predominantly rapidly adapting A-beta mechanoreceptors thus recruiting the same peripheral substrate as a horizontally moving brush on top of the skin. In patients with SMA we assumed an activation of Cbut also A-delta fibres from a static 10 s von Frey filament stimulus. The aim was to investigate if DMA and SMA could be assessed at perception threshold level using short or longer lasting usually non-painful von Frey filament prodding of the neuropathic skin. Patients and methods Eighteen patients with painful unilateral partial peripheral traumatic nerve injury suffering from SMA (n = 9) and/or DMA (n = 18) in a limb were studied. A compression/ischemia-induced (differential) nerve block in conjunction with repeated quantitative sensory testing of A-delta and C-fibre function using cold and warm stimuli was used to assess which nerve fibre population that contributes to pain at perception threshold level using 1 s (vF1) and 10 s (vF10) von Frey filament stimulation of the skin. Results The main outcome was the finding that elevation of vF1 and vF10 occurred simultaneously and significantly prior to an increase in the perception level to cold or warmth during the continuous nerve block. Single patients demonstrated a slight decrease in cold perception levels at the time of elevation of vF1 or vF10 and a possible contribution to mechanical allodynia from A-delta-fibres can therefore not completely be ruled out although the recorded alterations were minor. None of the patients reported an elevation of the perception level to warmth at the time of elevation of vF1 or vF10 excluding contribution from C-fibres. Further, only patients with clinically established SMA (n = 9) reported continuous pain to a sustained 10 s von Frey filament stimulation (vF10). Patients with only DMA (n = 9) reported pain merely for the initial 1-3 s of the total stimulus duration of 10 s and for a few seconds after the filament was lifted from the skin. Conclusions These findings support the role of A-beta fibres as peripheral mediators of both vF1 and vF10 although different receptor organs may be involved, i.e., rapidly (RA) and slowly (SA-I) adapting mechanoreceptors. Implications Techniques to quantify the different allodynias at perception threshold level deserve further attention as possible adjuncts to suprathreshold stimuli in intervention studies aimed at modifying these stimulus-evoked phenomena.

Quantitative somatosensory testing of the penis: optimizing the clinical neurological examination.

PubMed

Bleustein, Clifford B; Eckholdt, Haftan; Arezzo, Joseph C; Melman, Arnold

2003-06-01

Quantitative somatosensory testing, including vibration, pressure, spatial perception and thermal thresholds of the penis, has demonstrated neuropathy in patients with a history of erectile dysfunction of all etiologies. We evaluated which measurement of neurological function of the penis was best at predicting erectile dysfunction and examined the impact of location on the penis for quantitative somatosensory testing measurements. A total of 107 patients were evaluated. All patients were required to complete the erectile function domain of the International Index of Erectile Function (IIEF) questionnaire, of whom 24 had no complaints of erectile dysfunction and scored within the "normal" range on the IIEF. Patients were subsequently tested on ventral middle penile shaft, proximal dorsal midline penile shaft and glans penis (with foreskin retracted) for vibration, pressure, spatial perception, and warm and cold thermal thresholds. Mixed models repeated measures analysis of variance controlling for age, diabetes and hypertension revealed that method of measurement (quantitative somatosensory testing) was predictive of IIEF score (F = 209, df = 4,1315, p <0.001), while site of measurement on the penis was not. To determine the best method of measurement, we used hierarchical regression, which revealed that warm temperature was the best predictor of erectile dysfunction with pseudo R(2) = 0.19, p <0.0007. There was no significant improvement in predicting erectile dysfunction when another test was added. Using 37C and greater as the warm thermal threshold yielded a sensitivity of 88.5%, specificity 70.0% and positive predictive value 85.5%. Quantitative somatosensory testing using warm thermal threshold measurements taken at the glans penis can be used alone to assess the neurological status of the penis. Warm thermal thresholds alone offer a quick, noninvasive accurate method of evaluating penile neuropathy in an office setting.

Line length dependence of threshold current density and driving force in eutectic SnPb and SnAgCu solder electromigration

NASA Astrophysics Data System (ADS)

Yoon, Min-Seung; Ko, Min-Ku; Kim, Bit-Na; Kim, Byung-Joon; Park, Yong-Bae; Joo, Young-Chang

2008-04-01

The relationship between the threshold current density and the critical line length in eutectic SnPb and SnAgCu electromigrations were examined using solder lines with the various lengths ranging from 100to1000μm. When the electron wind-force was balanced by the back-stress gradient force, the net flux of electromigration is zero, at which the current density and line length are defined as the threshold current density and the critical length, respectively. It was found that in SnAgCu electromigration, the 1/L dependence on the threshold current density showed good agreement, whereas the threshold current densities of the eutectic SnPb deviated from the 1/L dependence. The balance between the electron wind-force and the back-stress gradient force was the main factor determining the threshold product of SnAgCu electromigration. On the other hand, in the case of eutectic SnPb, the chemical driving force is contributed as a back-flux force in addition to the back-stress gradient force. The existence of the chemical driving force was caused by the nonequilibrium Pb concentration inside the Pb-rich phases between the cathode and anode during the electromigration procedure.

Higher sensitivity to sweet and salty taste in obese compared to lean individuals.

PubMed

Hardikar, Samyogita; Höchenberger, Richard; Villringer, Arno; Ohla, Kathrin

2017-04-01

Although putatively taste has been associated with obesity as one of the factors governing food intake, previous studies have failed to find a consistent link between taste perception and Body Mass Index (BMI). A comprehensive comparison of both thresholds and hedonics for four basic taste modalities (sweet, salty, sour, and bitter) has only been carried out with a very small sample size in adults. In the present exploratory study, we compared 23 obese (OB; BMI > 30), and 31 lean (LN; BMI < 25) individuals on three dimensions of taste perception - recognition thresholds, intensity, and pleasantness - using different concentrations of sucrose (sweet), sodium chloride (NaCl; salty), citric acid (sour), and quinine hydrochloride (bitter) dissolved in water. Recognition thresholds were estimated with an adaptive Bayesian staircase procedure (QUEST). Intensity and pleasantness ratings were acquired using visual analogue scales (VAS). It was found that OB had lower thresholds than LN for sucrose and NaCl, indicating a higher sensitivity to sweet and salty tastes. This effect was also reflected in ratings of intensity, which were significantly higher in the OB group for the lower concentrations of sweet, salty, and sour. Calculation of Bayes factors further corroborated the differences observed with null-hypothesis significance testing (NHST). Overall, the results suggest that OB are more sensitive to sweet and salty, and perceive sweet, salty, and sour more intensely than LN. Copyright © 2016 Elsevier Ltd. All rights reserved.

Single bright light exposure decreases sweet taste threshold in healthy volunteers.

PubMed

Srivastava, Shrikant; Donaldson, Lucy F; Rai, Dheeraj; Melichar, Jan K; Potokar, John

2013-10-01

Bright light exposure can alter circulating serotonin levels, and alteration of available serotonin by acute selective serotonin reuptake inhibition significantly lowers sweet but not salt taste recognition thresholds. We tested the hypothesis that bright light exposure would increase sweet but not salt taste sensitivity in healthy adults. Fourteen healthy volunteers were exposed to bright (10,000 lux) and dim (<20 lux) light for 30 min each, in counterbalanced order. Measures of taste perception (salt and sweet) and mood were determined at baseline, and before and after each light exposure period. Recognition thresholds for sucrose were significantly lower after bright but not dim light exposure. Thresholds for salt were unaffected by either condition. There were no significant changes in taste acuity, intensity or pleasantness for both the taste modalities and on visual analogue scales (VASs) for mood, anxiety, sleepiness and alertness, under either light condition. Brief bright light exposure reduces sweet but not salt taste recognition thresholds in healthy humans.

Relationship between behavioral and physiological spectral-ripple discrimination.

PubMed

Won, Jong Ho; Clinard, Christopher G; Kwon, Seeyoun; Dasika, Vasant K; Nie, Kaibao; Drennan, Ward R; Tremblay, Kelly L; Rubinstein, Jay T

2011-06-01

Previous studies have found a significant correlation between spectral-ripple discrimination and speech and music perception in cochlear implant (CI) users. This relationship could be of use to clinicians and scientists who are interested in using spectral-ripple stimuli in the assessment and habilitation of CI users. However, previous psychoacoustic tasks used to assess spectral discrimination are not suitable for all populations, and it would be beneficial to develop methods that could be used to test all age ranges, including pediatric implant users. Additionally, it is important to understand how ripple stimuli are processed in the central auditory system and how their neural representation contributes to behavioral performance. For this reason, we developed a single-interval, yes/no paradigm that could potentially be used both behaviorally and electrophysiologically to estimate spectral-ripple threshold. In experiment 1, behavioral thresholds obtained using the single-interval method were compared to thresholds obtained using a previously established three-alternative forced-choice method. A significant correlation was found (r = 0.84, p = 0.0002) in 14 adult CI users. The spectral-ripple threshold obtained using the new method also correlated with speech perception in quiet and noise. In experiment 2, the effect of the number of vocoder-processing channels on the behavioral and physiological threshold in normal-hearing listeners was determined. Behavioral thresholds, using the new single-interval method, as well as cortical P1-N1-P2 responses changed as a function of the number of channels. Better behavioral and physiological performance (i.e., better discrimination ability at higher ripple densities) was observed as more channels added. In experiment 3, the relationship between behavioral and physiological data was examined. Amplitudes of the P1-N1-P2 "change" responses were significantly correlated with d' values from the single-interval behavioral procedure. Results suggest that the single-interval procedure with spectral-ripple phase inversion in ongoing stimuli is a valid approach for measuring behavioral or physiological spectral resolution.

The self-perception of dyspnoea threshold during the 6-min walk test: a good alternative to estimate the ventilatory threshold in chronic obstructive pulmonary disease.

PubMed

Couillard, Annabelle; Tremey, Emilie; Prefaut, Christian; Varray, Alain; Heraud, Nelly

2016-12-01

To determine and/or adjust exercise training intensity for patients when the cardiopulmonary exercise test is not accessible, the determination of dyspnoea threshold (defined as the onset of self-perceived breathing discomfort) during the 6-min walk test (6MWT) could be a good alternative. The aim of this study was to evaluate the feasibility and reproducibility of self-perceived dyspnoea threshold and to determine whether a useful equation to estimate ventilatory threshold from self-perceived dyspnoea threshold could be derived. A total of 82 patients were included and performed two 6MWTs, during which they raised a hand to signal self-perceived dyspnoea threshold. The reproducibility in terms of heart rate (HR) was analysed. On a subsample of patients (n=27), a stepwise regression analysis was carried out to obtain a predictive equation of HR at ventilatory threshold measured during a cardiopulmonary exercise test estimated from HR at self-perceived dyspnoea threshold, age and forced expiratory volume in 1 s. Overall, 80% of patients could identify self-perceived dyspnoea threshold during the 6MWT. Self-perceived dyspnoea threshold was reproducibly expressed in HR (coefficient of variation=2.8%). A stepwise regression analysis enabled estimation of HR at ventilatory threshold from HR at self-perceived dyspnoea threshold, age and forced expiratory volume in 1 s (adjusted r=0.79, r=0.63, and relative standard deviation=9.8 bpm). This study shows that a majority of patients with chronic obstructive pulmonary disease can identify a self-perceived dyspnoea threshold during the 6MWT. This HR at the dyspnoea threshold is highly reproducible and enable estimation of the HR at the ventilatory threshold.

Perception Evolution Network Based on Cognition Deepening Model--Adapting to the Emergence of New Sensory Receptor.

PubMed

Xing, Youlu; Shen, Furao; Zhao, Jinxi

2016-03-01

The proposed perception evolution network (PEN) is a biologically inspired neural network model for unsupervised learning and online incremental learning. It is able to automatically learn suitable prototypes from learning data in an incremental way, and it does not require the predefined prototype number or the predefined similarity threshold. Meanwhile, being more advanced than the existing unsupervised neural network model, PEN permits the emergence of a new dimension of perception in the perception field of the network. When a new dimension of perception is introduced, PEN is able to integrate the new dimensional sensory inputs with the learned prototypes, i.e., the prototypes are mapped to a high-dimensional space, which consists of both the original dimension and the new dimension of the sensory inputs. In the experiment, artificial data and real-world data are used to test the proposed PEN, and the results show that PEN can work effectively.

Global motion perception is related to motor function in 4.5-year-old children born at risk of abnormal development

PubMed Central

Chakraborty, Arijit; Anstice, Nicola S.; Jacobs, Robert J.; Paudel, Nabin; LaGasse, Linda L.; Lester, Barry M.; McKinlay, Christopher J. D.; Harding, Jane E.; Wouldes, Trecia A.; Thompson, Benjamin

2017-01-01

Global motion perception is often used as an index of dorsal visual stream function in neurodevelopmental studies. However, the relationship between global motion perception and visuomotor control, a primary function of the dorsal stream, is unclear. We measured global motion perception (motion coherence threshold; MCT) and performance on standardized measures of motor function in 606 4.5-year-old children born at risk of abnormal neurodevelopment. Visual acuity, stereoacuity and verbal IQ were also assessed. After adjustment for verbal IQ or both visual acuity and stereoacuity, MCT was modestly, but significantly, associated with all components of motor function with the exception of gross motor scores. In a separate analysis, stereoacuity, but not visual acuity, was significantly associated with both gross and fine motor scores. These results indicate that the development of motion perception and stereoacuity are associated with motor function in pre-school children. PMID:28435122

Emotion colors time perception unconsciously.

PubMed

Yamada, Yuki; Kawabe, Takahiro

2011-12-01

Emotion modulates our time perception. So far, the relationship between emotion and time perception has been examined with visible emotional stimuli. The present study investigated whether invisible emotional stimuli affected time perception. Using continuous flash suppression, which is a kind of dynamic interocular masking, supra-threshold emotional pictures were masked or unmasked depending on whether the retinal position of continuous flashes on one eye was consistent with that of the pictures on the other eye. Observers were asked to reproduce the perceived duration of a frame stimulus that was concurrently presented with a masked or unmasked emotional picture. As a result, negative emotional stimuli elongated the perceived duration of the frame stimulus in comparison with positive and neutral emotional stimuli, regardless of the visibility of emotional pictures. These results suggest that negative emotion unconsciously accelerates an internal clock, altering time perception. Copyright © 2011 Elsevier Inc. All rights reserved.

The role of spatial integration in the perception of surface orientation with active touch.

PubMed

Giachritsis, Christos D; Wing, Alan M; Lovell, Paul G

2009-10-01

Vision research has shown that perception of line orientation, in the fovea area, improves with line length (Westheimer & Ley, 1997). This suggests that the visual system may use spatial integration to improve perception of orientation. In the present experiments, we investigated the role of spatial integration in the perception of surface orientation using kinesthetic and proprioceptive information from shoulder and elbow. With their left index fingers, participants actively explored virtual slanted surfaces of different lengths and orientations, and were asked to reproduce an orientation or discriminate between two orientations. Results showed that reproduction errors and discrimination thresholds improve with surface length. This suggests that the proprioceptive shoulder-elbow system may integrate redundant spatial information resulting from extended arm movements to improve orientation judgments.

Spontaneous recombination current in InGaAs/GaAs quantum well lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blood, P.; Fletcher, E.D.; Woodbridge, K.

1990-10-08

We have studied the intrinsic factors which determine the threshold current and its temperature dependence in 160-A-wide In{sub 0.2}Ga{sub 0.8}As single well quantum lasers with GaAs barriers, grown by molecular beam epitaxy on GaAs substrates. By measuring the relative temperature dependence of the spontaneous emission intensity at threshold we show that radiative transitions between higher order ({ital n}=2,3) electron and heavy hole subbands make a significant contribution to the threshold current and its temperature sensitivity, even in devices where the laser transitions are between {ital n}=1 subbands. These higher transitions will also influence the dependence of threshold current and itsmore » temperature sensitivity on well width.« less

Sensory function assessment of the human male lower urinary tract using current perception thresholds.

PubMed

Knüpfer, Stephanie C; Liechti, Martina D; Gregorini, Flavia; De Wachter, Stefan; Kessler, Thomas M; Mehnert, Ulrich

2017-02-01

To evaluate the feasibility and reliability of current perception threshold (CPT) measurement for sensory assessment of distinct locations in the male lower urinary tract (LUT). Twelve male subjects (>18 years) without LUT symptoms or medical comorbidities were eligible. CPTs were determined twice (interval: 7-20 days) at the bladder dome, trigone and the proximal, membranous, and distal urethra. Square wave electrical stimulation of 3 Hz/0.2 ms and 0.5 Hz/1 ms was applied using a transurethral 8F catheter placed under fluoroscopic control. Bladder volume was kept constant (60 mL) using a second 10F catheter. Repetitive measurements and reliability were assessed by analysis of variance (ANOVA) and intraclass correlation coefficient (ICC). The ANOVA revealed significant main effects for stimulation site (P = 0.008) and type of stimulation (P < 0.001) with lower CPTs for 0.5 Hz/1 ms compared to 3 Hz/0.2 ms. There was no significant effect for visit number (P = 0.061). CPTs were higher for bladder dome than for proximal (0.5 Hz/1 ms: P = 0.022; 3 Hz/0.2 ms: P = 0.022) and distal urethra (0.5 Hz/1 ms: P = 0.026; 3 Hz/0.2 ms: P = 0.030). Reliability of CPT measurements was excellent to good (ICC = 0.67-0.96) except for the bladder dome (5 Hz/1 ms: ICC = 0.45; 3 Hz/0.2 ms: ICC = 0.20) and distal urethra (3 Hz/0.2 ms: ICC = 0.57). CPTs can be reliably detected at different LUT locations. However, alert and compliant subjects are essential. CPTs of LUT may become a complementary assessment method providing information on responsiveness and sensitivity of afferent LUT nerves. This is especially relevant for urethral afferents, which are not covered by standard urodynamic investigations. Neurourol. Urodynam. 36:469-473, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

How Can Paresthesia After Zygomaticomaxillary Complex Fracture Be Determined After Long-Term Follow-Up? A New and Quantitative Evaluation Method Using Current Perception Threshold Testing.

PubMed

Okochi, Masayuki; Ueda, Kazuki; Mochizuki, Yasushi; Okochi, Hiromi

2015-08-01

The aims of the present study were to analyze the effectiveness of current perception threshold (CPT) testing to determine patients' minor paresthesia of the infraorbital region after open reduction and internal fixation (ORIF) for unilateral zygomaticomaxillary bone fracture (UZF) and to clarify which nerve fiber was related to the paresthesia. We conducted a retrospective cohort study of patients who had undergone ORIF after UZF. We also performed neurosensory testing for healthy volunteers who served as the control group. The predictor variables were the period of measurement of Semmes-Weinstein monofilament (S-W) testing and CPT testing (preoperatively and 1 and 5 years postoperatively), measurement side, and disease status (UZF or control). The outcome variables were paresthesia status of the infraorbital nerve region and the results of S-W and CPT testing in both UZF and control groups. The differences in the S-W and CPT values between the affected and unaffected sides in the UZF group and between the UZF and control groups were analyzed by t test (P < .05 was considered significant). The present study included 10 patients (6 males and 4 females), with an average age of 25.0 ± 12.7 years, and 21 controls (10 males and 11 females), with an average age of 24.3 ± 1.7 years. In the control group, the CPT and S-W test results did not show any significant differences between the left and right sides. All 10 patients had paresthesia at 1 and 5 years postoperatively. At 5 years postoperatively, the S-W values in all patients showed normalization. From the results of CPT testing, only the A-β fiber function showed significant improvement at 5 years postoperatively. The CPT test was an effective sensory test for determining minor paresthesia that could not be detected using S-W testing. Paresthesia of the infraorbital nerve region was caused by the damaged A-δ and C fibers. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Cathodal transcranial direct-current stimulation over right posterior parietal cortex enhances human temporal discrimination ability.

PubMed

Oyama, Fuyuki; Ishibashi, Keita; Iwanaga, Koichi

2017-12-04

Time perception associated with durations from 1 s to several minutes involves activity in the right posterior parietal cortex (rPPC). It is unclear whether altering the activity of the rPPC affects an individual's timing performance. Here, we investigated the human timing performance under the application of transcranial direct-current stimulation (tDCS) that altered the neural activities of the rPPC. We measured the participants' duration-discrimination threshold by administering a behavioral task during the tDCS application. The tDCS conditions consisted of anodal, cathodal, and sham conditions. The electrodes were placed over the P4 position (10-20 system) and on the left supraorbital forehead. On each task trial, the participant observed two visual stimuli and indicated which was longer. The amount of difference between the two stimulus durations was varied repeatedly throughout the trials according to the participant's responses. The correct answer rate of the trials was calculated for each amount of difference, and the minimum amount with the correct answer rate exceeding 75% was selected as the threshold. The data were analyzed by a linear mixed-effects models procedure. Nineteen volunteers participated in the experiment. We excluded three participants from the analysis: two who reported extreme sleepiness while performing the task and one who could recognize the sham condition correctly with confidence. Our analysis of the 16 participants' data showed that the average value of the thresholds observed under the cathodal condition was lower than that of the sham condition. This suggests that inhibition of the rPPC leads to an improvement in temporal discrimination performance, resulting in improved timing performance. In the present study, we found a new effect that cathodal tDCS over the rPPC enhances temporal discrimination performance. In terms of the existence of anodal/cathodal tDCS effects on human timing performance, the results were consistent with a previous study that investigated temporal reproduction performance during tDCS application. However, the results of the current study further indicated that cathodal tDCS over the rPPC increases accuracy of observed time duration rather than inducing an overestimation as a previous study reported.

Loss of idealism or realistic optimism? A cross-sectional analysis of dental hygiene students' and registered dental hygienists' professional identity perceptions.

PubMed

Champine, J M; Inglehart, M R; Furgeson, D; Halaris, J F; Fitzgerald, M; Danciu, T E; Kinney, J S

2018-02-01

The dental hygiene profession in the U.S. is in the process of establishing a direct access model of care and contributing to the creation of the profession of a dental therapist. The objectives were to analyse the professional role perceptions of dental hygiene students and registered dental hygienists in these times of change. Specifically, it was explored whether dental hygiene students' current professional identities differ (i) from their expected future identities, and (ii) from dental hygienists' current and (iii) past identities. Survey data were collected from 215 dental hygiene students concerning their present and future role perceptions, and from 352 registered dental hygienists concerning their present and past professional identity perceptions. Students' future professional identity perceptions were even more positive than their very positive current perceptions of their professional role components. Students' current perceptions of professional pride, professional ambition, work ethic and patient relations were more positive than dental hygienists' current perceptions of these professional role components. A comparison of students' current perceptions with dental hygienists' current and retrospective descriptions showed that students were more positive than dental hygienists in each case. The fact that dental hygienists had less positive role perceptions than dental hygiene students might lead to the conclusion that a loss of idealism occurs over the course of a professional lifespan. However, dental hygienists actually improved their role perceptions over time and students' future descriptions were more positive than their current descriptions, supporting the interpretation that realistic optimism dominates professional role perceptions in these times of change. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Methods of scaling threshold color difference using printed samples

NASA Astrophysics Data System (ADS)

Huang, Min; Cui, Guihua; Liu, Haoxue; Luo, M. Ronnier

2012-01-01

A series of printed samples on substrate of semi-gloss paper and with the magnitude of threshold color difference were prepared for scaling the visual color difference and to evaluate the performance of different method. The probabilities of perceptibly was used to normalized to Z-score and different color differences were scaled to the Z-score. The visual color difference was got, and checked with the STRESS factor. The results indicated that only the scales have been changed but the relative scales between pairs in the data are preserved.

Man-systems evaluation of moving base vehicle simulation motion cues. [human acceleration perception involving visual feedback

NASA Technical Reports Server (NTRS)

Kirkpatrick, M.; Brye, R. G.

1974-01-01

A motion cue investigation program is reported that deals with human factor aspects of high fidelity vehicle simulation. General data on non-visual motion thresholds and specific threshold values are established for use as washout parameters in vehicle simulation. A general purpose similator is used to test the contradictory cue hypothesis that acceleration sensitivity is reduced during a vehicle control task involving visual feedback. The simulator provides varying acceleration levels. The method of forced choice is based on the theory of signal detect ability.

Reliability of TMS phosphene threshold estimation: Toward a standardized protocol.

PubMed

Mazzi, Chiara; Savazzi, Silvia; Abrahamyan, Arman; Ruzzoli, Manuela

Phosphenes induced by transcranial magnetic stimulation (TMS) are a subjectively described visual phenomenon employed in basic and clinical research as index of the excitability of retinotopically organized areas in the brain. Phosphene threshold estimation is a preliminary step in many TMS experiments in visual cognition for setting the appropriate level of TMS doses; however, the lack of a direct comparison of the available methods for phosphene threshold estimation leaves unsolved the reliability of those methods in setting TMS doses. The present work aims at fulfilling this gap. We compared the most common methods for phosphene threshold calculation, namely the Method of Constant Stimuli (MOCS), the Modified Binary Search (MOBS) and the Rapid Estimation of Phosphene Threshold (REPT). In two experiments we tested the reliability of PT estimation under each of the three methods, considering the day of administration, participants' expertise in phosphene perception and the sensitivity of each method to the initial values used for the threshold calculation. We found that MOCS and REPT have comparable reliability when estimating phosphene thresholds, while MOBS estimations appear less stable. Based on our results, researchers and clinicians can estimate phosphene threshold according to MOCS or REPT equally reliably, depending on their specific investigation goals. We suggest several important factors for consideration when calculating phosphene thresholds and describe strategies to adopt in experimental procedures. Copyright © 2017 Elsevier Inc. All rights reserved.

Perceptibility curve test for digital radiographs before and after correction for attenuation and correction for attenuation and visual response.

PubMed

Li, G; Welander, U; Yoshiura, K; Shi, X-Q; McDavid, W D

2003-11-01

Two digital image processing methods, correction for X-ray attenuation and correction for attenuation and visual response, have been developed. The aim of the present study was to compare digital radiographs before and after correction for attenuation and correction for attenuation and visual response by means of a perceptibility curve test. Radiographs were exposed of an aluminium test object containing holes ranging from 0.03 mm to 0.30 mm with increments of 0.03 mm. Fourteen radiographs were exposed with the Dixi system (Planmeca Oy, Helsinki, Finland) and twelve radiographs were exposed with the F1 iOX system (Fimet Oy, Monninkylä, Finland) from low to high exposures covering the full exposure ranges of the systems. Radiographs obtained from the Dixi and F1 iOX systems were 12 bit and 8 bit images, respectively. Original radiographs were then processed for correction for attenuation and correction for attenuation and visual response. Thus, two series of radiographs were created. Ten viewers evaluated all the radiographs in the same random order under the same viewing conditions. The object detail having the lowest perceptible contrast was recorded for each observer. Perceptibility curves were plotted according to the mean of observer data. The perceptibility curves for processed radiographs obtained with the F1 iOX system are higher than those for originals in the exposure range up to the peak, where the curves are basically the same. For radiographs exposed with the Dixi system, perceptibility curves for processed radiographs are higher than those for originals for all exposures. Perceptibility curves show that for 8 bit radiographs obtained from the F1 iOX system, the contrast threshold was increased in processed radiographs up to the peak, while for 12 bit radiographs obtained with the Dixi system, the contrast threshold was increased in processed radiographs for all exposures. When comparisons were made between radiographs corrected for attenuation and corrected for attenuation and visual response, basically no differences were found. Radiographs processed for correction for attenuation and correction for attenuation and visual response may improve perception, especially for 12 bit originals.

Functional brain measurements within the prefrontal area on pseudo-"blindsight" induced by extremely low frequency electromagnetic stimulations

NASA Astrophysics Data System (ADS)

Nakagawa, Hidenori; Ueno, Shoogo

2015-05-01

For evaluating the effects of phosphene as pseudo-blindsight closely, we used functional near-infrared spectroscopy to investigate whether or not the phosphene appearance itself substantially affects the hemodynamic responses of the prefrontal area. Seven healthy volunteers ranging in age from 22 to 72 participated in the visual stimulation experiments. First, we examined the influences of electromagnetic stimulations at around the threshold (10 mT) for a blindsight-like phosphene on the responses. According to the results of the aged volunteers, we found the possibility that the delay in the phosphene perception might be caused by aging beyond a certain age. In the results of our measurements using the stimulation of 50 mT, no significant difference in the perception delay for all the volunteers could be detected. When the field strength was decreased from 50 mT to the threshold in steps of 10 mT, the results obtained at the threshold are equivalent to that obtained at 50 mT. Our data strongly support the hypothesis that pseudo-blindsight induced by electromagnetic stimulation of above 50 mT is able to excite all the volunteers' retinal photoreceptor cells provisionally. Hence the continuous stimulations for a long period of time might gradually activate synaptic plasticity on the neural network of the retina.

Unconscious perception: a model-based approach to method and evidence.

PubMed

Snodgrass, Michael; Bernat, Edward; Shevrin, Howard

2004-07-01

Unconscious perceptual effects remain controversial because it is hard to rule out alternative conscious perception explanations for them. We present a novel methodological framework, stressing the centrality of specifying the single-process conscious perception model (i.e., the null hypothesis). Various considerations, including those of SDT (Macmillan & Creelman, 1991), suggest that conscious perception functions hierarchically, in such a way that higher level effects (e.g., semantic priming) should not be possible without lower level discrimination (i.e., detection and identification). Relatedly, alternative conscious perception accounts (as well as the exhaustiveness, null sensitivity, and exclusiveness problems-Reingold & Merikle, 1988, 1990) predict positive relationships between direct and indirect measures. Contrariwise, our review suggests that negative and/or nonmonotonic relationships are found, providing strong evidence for unconscious perception and further suggesting that conscious and unconscious perceptual influences are functionally exclusive (cf. Jones, 1987), in such a way that the former typically override the latter when both are present. Consequently, unconscious perceptual effects manifest reliably only when conscious perception is completely absent, which occurs at the objective detection (but not identification) threshold.

Repeated noxious stimulation of the skin enhances cutaneous pain perception of migraine patients in-between attacks: clinical evidence for continuous sub-threshold increase in membrane excitability of central trigeminovascular neurons.

PubMed

Weissman-Fogel, Irit; Sprecher, Elliot; Granovsky, Yelena; Yarnitsky, David

2003-08-01

Recent clinical studies showed that acute migraine attacks are accompanied by increased periorbital and bodily skin sensitivity to touch, heat and cold. Parallel pre-clinical studies showed that the underlying mechanism is sensitization of primary nociceptors and central trigeminovascular neurons. The present study investigates the sensory state of neuronal pathways that mediate skin pain sensation in migraine patients in between attacks. The assessments of sensory perception included (a) mechanical and thermal pain thresholds of the periorbital area, electrical pain threshold of forearm skin, (b) pain scores to phasic supra-threshold stimuli in the same modalities and areas as above, and (c) temporal summation of pain induced by applying noxious tonic heat pain and brief trains of noxious mechanical and electrical pulses to the above skin areas. Thirty-four pain-free migraine patients and 28 age- and gender-matched controls were studied. Patients did not differ from controls in their pain thresholds for heat (44+/-2.6 vs. 44.6+/-1.9 degrees C), and electrical (4.8+/-1.6 vs. 4.3+/-1.6 mA) stimulation, and in their pain scores for supra-threshold phasic stimuli for all modalities. They did, however, differ in their pain threshold for mechanical stimulation, just by one von Frey filament (P=0.01) and in their pain scores of the temporal summation tests. Increased summation of pain was found in migraineurs for repeated mechanical stimuli (delta visual analog scale (VAS) +2.32+/-0.73 in patients vs. +0.16+/-0.83 in controls, P=0.05) and repeated electrical stimuli (delta VAS +3.83+/-1.91 vs -3.79+/-2.31, P=0.01). Increased summation corresponded with more severe clinical parameters of migraine and tended to depend on interval since last migraine attack. The absence of clinically or overt laboratory expressed allodynia suggests that pain pathways are not sensitized in the pain-free migraine patients. Nevertheless, the increased temporal summation, and the slight decrease in mechanical pain thresholds, suggest that central nociceptive neurons do express activation-dependent plasticity. These findings may point to an important pathophysiological change in membrane properties of nociceptive neurons of migraine patients; a change that may hold a key to more effective prophylactic treatment.

Improved outcomes in auditory brainstem implantation with the use of near-field electrical compound action potentials.

PubMed

Mandalà, Marco; Colletti, Liliana; Colletti, Giacomo; Colletti, Vittorio

2014-12-01

To compare the outcomes (auditory threshold and open-set speech perception at 48-month follow-up) of a new near-field monitoring procedure, electrical compound action potential, on positioning the auditory brainstem implant electrode array on the surface of the cochlear nuclei versus the traditional far-field electrical auditory brainstem response. Retrospective study. Tertiary referral center. Among the 202 patients with auditory brainstem implants fitted and monitored with electrical auditory brainstem response during implant fitting, 9 also underwent electrical compound action potential recording. These subjects were matched retrospectively with a control group of 9 patients in whom only the electrical auditory brainstem response was recorded. Electrical compound action potentials were obtained using a cotton-wick recording electrode located near the surface of the cochlear nuclei and on several cranial nerves. Significantly lower potential thresholds were observed with the recording electrode located on the cochlear nuclei surface compared with the electrical auditory brainstem response (104.4 ± 32.5 vs 158.9 ± 24.2, P = .0030). Electrical brainstem response and compound action potentials identified effects on the neighboring cranial nerves on 3.2 ± 2.4 and 7.8 ± 3.2 electrodes, respectively (P = .0034). Open-set speech perception outcomes at 48-month follow-up had improved significantly in the near- versus far-field recording groups (78.9% versus 56.7%; P = .0051). Electrical compound action potentials during auditory brainstem implantation significantly improved the definition of the potential threshold and the number of auditory and extra-auditory waves generated. It led to the best coupling between the electrode array and cochlear nuclei, significantly improving the overall open-set speech perception. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.

Obese Women Have Lower Monosodium Glutamate Taste Sensitivity and Prefer Higher Concentrations Than Do Normal-weight Women

PubMed Central

Pepino, M. Yanina; Finkbeiner, Susana; Beauchamp, Gary K.; Mennella, Julie A.

2010-01-01

The goal of this study was to determine whether obese women exhibit altered umami and sweet taste perception compared to normal-weight women. A total of 57 subjects (23 obese and 34 normal weight) participated in a 2-day study separated by 1 week. Half of the women in each group were evaluated using monosodium glutamate (MSG; prototypical umami stimulus) on the first test day and sucrose on the second test day; the order was reversed for the remaining women. We used two-alternative forced-choice staircase procedures to measure taste detection thresholds, forced-choice tracking technique to measure preferences, the general Labeled Magnitude Scale (gLMS) to measure perceived intensity of suprathreshold concentrations, and a triangle test to measure discrimination between 29 mmol/l MSG and 29 mmol/l NaCl. Obese women required higher MSG concentrations to detect a taste and preferred significantly higher MSG concentrations in a soup-like vehicle. However, their perception of MSG at suprathreshold concentrations, their ability to discriminate MSG from salt, and their preference for sucrose were similar to that observed in normal-weight women. Regardless of their body weight category, 28% of the women did not discriminate 29 mmol/l MSG from 29 mmol/l NaCl (nondiscriminators). Surprisingly, we found that, relative to discriminators, nondiscriminators perceived less savoriness when tasting suprathreshold MSG concentrations and less sweetness from suprathreshold sucrose concentrations but had similar MSG and sucrose detection thresholds. Taken together, these data suggest that body weight is related to some components of umami taste and that different mechanisms are involved in the perception of threshold and suprathreshold MSG concentrations. PMID:20075854

Removing own-limb visual input using mixed reality (MR) produces a "telescoping" illusion in healthy individuals.

PubMed

Thøgersen, Mikkel; Hansen, John; Arendt-Nielsen, Lars; Flor, Herta; Petrini, Laura

2018-07-16

The purpose of the present study was to assess changes in body perception when visual feedback was removed from the hand and arm with the purpose of resembling the visual deprivation arising from amputation. The illusion was created by removing the visual feedback from the participants' own left forearm using a mixed reality (MR) and green screen environment. Thirty healthy persons (15 female) participated in the study. Each subject experienced two MR conditions, one with and one without visual feedback from the left hand, and a baseline condition with normal vision of the limb (no MR). Body perception was assessed using proprioceptive drift, questionnaires on body perception, and thermal sensitivity measures (cold, warm, heat pain and cold pain detection thresholds). The proprioceptive drift showed a significant shift of the tip of the index finger (p<0.001) towards the elbow in the illusion condition (mean drift: -3.71 cm). Self-report showed a significant decrease in ownership (p<0.001), shift in perceptual distortions, (e.g. "It feels as if my lower arm has become shorter") (p=0.025), and changes in sensations of the hand (tingling, tickling) (p=0.025). A significant decrease was also observed in cold detection threshold (p<0.001), i.e. the detection threshold was cooler than for the control conditions. The proprioceptive drift together with the self-reported questionnaire showed that the participants felt a proximal retraction of their limb, resembling the telescoping experienced by phantom limb patients. The study highlights the influence of missing visual feedback and its possible contribution to phantom limb phenomena. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis of polymer nanostructures with conductance switching properties

DOEpatents

Su, Kai; Nuraje, Nurxat; Zhang, Lingzhi; Matsui, Hiroshi; Yang, Nan Loh

2015-03-03

The present invention is directed to crystalline organic polymer nanoparticles comprising a conductive organic polymer; wherein the crystalline organic polymer nanoparticles have a size of from 10 nm to 200 nm and exhibits two current-voltage states: (1) a high resistance current-voltage state, and (2) a low resistance current-voltage state, wherein when a first positive threshold voltage (V.sub.th1) or higher positive voltage, or a second negative threshold voltage (V.sub.th2) or higher negative voltage is applied to the nanoparticle, the nanoparticle exhibits the low-resistance current-voltage state, and when a voltage less positive than the first positive threshold voltage or a voltage less negative than the second negative threshold voltage is applied to the nanoparticle, the nanoparticle exhibits the high-resistance current-voltage state. The present invention is also directed methods of manufacturing the nanoparticles using novel interfacial oxidative polymerization techniques.

Investigating the effect of freeway congestion thresholds on decision-making inputs.

DOT National Transportation Integrated Search

2010-05-01

Congestion threshold is embedded in the congestion definition. Two basic approaches exist in : current practice for setting the congestion threshold. One common approach uses the free-flow or : unimpeded conditions as the congestion threshold. ...

Psychophysics with children: Investigating the effects of attentional lapses on threshold estimates.

PubMed

Manning, Catherine; Jones, Pete R; Dekker, Tessa M; Pellicano, Elizabeth

2018-03-26

When assessing the perceptual abilities of children, researchers tend to use psychophysical techniques designed for use with adults. However, children's poorer attentiveness might bias the threshold estimates obtained by these methods. Here, we obtained speed discrimination threshold estimates in 6- to 7-year-old children in UK Key Stage 1 (KS1), 7- to 9-year-old children in Key Stage 2 (KS2), and adults using three psychophysical procedures: QUEST, a 1-up 2-down Levitt staircase, and Method of Constant Stimuli (MCS). We estimated inattentiveness using responses to "easy" catch trials. As expected, children had higher threshold estimates and made more errors on catch trials than adults. Lower threshold estimates were obtained from psychometric functions fit to the data in the QUEST condition than the MCS and Levitt staircases, and the threshold estimates obtained when fitting a psychometric function to the QUEST data were also lower than when using the QUEST mode. This suggests that threshold estimates cannot be compared directly across methods. Differences between the procedures did not vary significantly with age group. Simulations indicated that inattentiveness biased threshold estimates particularly when threshold estimates were computed as the QUEST mode or the average of staircase reversals. In contrast, thresholds estimated by post-hoc psychometric function fitting were less biased by attentional lapses. Our results suggest that some psychophysical methods are more robust to attentiveness, which has important implications for assessing the perception of children and clinical groups.

Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis

PubMed Central

Iwai, Yuta; Shibuya, Kazumoto; Misawa, Sonoko; Sekiguchi, Yukari; Watanabe, Keisuke; Amino, Hiroshi; Kuwabara, Satoshi

2016-01-01

Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS. PMID:27383069

Dependence of threshold current on the number of wells in AlGaAs-GaAs quantum well lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blood, P.; Fletcher, E.D.; Woodbridge, K.

1985-08-01

GaAs-AlGaAs multiple quantum well injection lasers have been grown by molecular beam epitaxy with different numbers (N) of uncoupled GaAs wells 25 A wide symmetrically disposed about the center of a 4000-A-wide waveguide. The devices emit at about 770 nm and for N = 4 the broad area threshold current density is 1.1 kA cm/sup -2/. The threshold current increases with increasing N (2

Understanding face perception by means of human electrophysiology.

PubMed

Rossion, Bruno

2014-06-01

Electrophysiological recordings on the human scalp provide a wealth of information about the temporal dynamics and nature of face perception at a global level of brain organization. The time window between 100 and 200 ms witnesses the transition between low-level and high-level vision, an N170 component correlating with conscious interpretation of a visual stimulus as a face. This face representation is rapidly refined as information accumulates during this time window, allowing the individualization of faces. To improve the sensitivity and objectivity of face perception measures, it is increasingly important to go beyond transient visual stimulation by recording electrophysiological responses at periodic frequency rates. This approach has recently provided face perception thresholds and the first objective signature of integration of facial parts in the human brain. Copyright © 2014 Elsevier Ltd. All rights reserved.

How to reinforce perception of depth in single two-dimensional pictures

NASA Technical Reports Server (NTRS)

Nagata, S.

1989-01-01

The physical conditions of the display of single 2-D pictures, which produce images realistically, were studied by using the characteristics of the intake of the information for visual depth perception. Depth sensitivity, which is defined as the ratio of viewing distance to depth discrimination threshold, was introduced in order to evaluate the availability of various cues for depth perception: binocular parallax, motion parallax, accommodation, convergence, size, texture, brightness, and air-perspective contrast. The effects of binocular parallax in different conditions, the depth sensitivity of which is greatest at a distance of up to about 10 m, were studied with the new versatile stereoscopic display. From these results, four conditions to reinforce the perception of depth in single pictures were proposed, and these conditions are met by the old viewing devices and the new high-definition and wide television displays.

The extreme relativity of perception: A new contextual effect modulates human resolving power.

PubMed

Namdar, Gal; Ganel, Tzvi; Algom, Daniel

2016-04-01

The authors report the discovery of a new effect of context that modulates human resolving power with respect to an individual stimulus. They show that the size of the difference threshold or the just noticeable difference around a standard stimulus depends on the range of the other standards tested simultaneously for resolution within the same experimental session. The larger this range, the poorer the resolving power for a given standard. The authors term this effect the range of standards effect (RSE). They establish this result both in the visual domain for the perception of linear extent, and in the somatosensory domain for the perception of weight. They discuss the contingent nature of stimulus resolution in perception and psychophysics and contrast it with the immunity to contextual influences of visually guided action. (c) 2016 APA, all rights reserved).

Conscious and Nonconscious Processes:Distinct Forms of Evidence Accumulation?

NASA Astrophysics Data System (ADS)

Dehaene, Stanislas

Among the many brain events evoked by a visual stimulus, which ones are associated specifically with conscious perception, and which merely reflect nonconscious processing? Understanding the neuronal mechanisms of consciousness is a major challenge for cognitive neuroscience. Recently, progress has been achieved by contrasting behavior and brain activation in minimally different experimental conditions, one of which leads to conscious perception whereas the other does not. This chapter reviews briefly this line of research and speculates on its theoretical interpretation. I propose to draw links between evidence accumulation models, which are highly successful in capturing elementary psychophysical decisions, and the conscious/nonconscious dichotomy. In this framework, conscious access would correspond to the crossing of a threshold in evidence accumulation within a distributed global workspace, a set of recurrently connected neurons with long axons that is able to integrate and broadcast back evidence from multiple brain processors. During nonconscious processing, evidence would be accumulated locally within specialized subcircuits, but would fail to reach the threshold needed for global ignition and, therefore, conscious reportability.

Visual processing speed in old age.

PubMed

Habekost, Thomas; Vogel, Asmus; Rostrup, Egill; Bundesen, Claus; Kyllingsbaek, Søren; Garde, Ellen; Ryberg, Charlotte; Waldemar, Gunhild

2013-04-01

Mental speed is a common concept in theories of cognitive aging, but it is difficult to get measures of the speed of a particular psychological process that are not confounded by the speed of other processes. We used Bundesen's (1990) Theory of Visual Attention (TVA) to obtain specific estimates of processing speed in the visual system controlled for the influence of response latency and individual variations of the perception threshold. A total of 33 non-demented old people (69-87 years) were tested for the ability to recognize briefly presented letters. Performance was analyzed by the TVA model. Visual processing speed decreased approximately linearly with age and was on average halved from 70 to 85 years. Less dramatic aging effects were found for the perception threshold and the visual apprehension span. In the visual domain, cognitive aging seems to be most clearly related to reductions in processing speed. © 2012 The Authors. Scandinavian Journal of Psychology © 2012 The Scandinavian Psychological Associations.

Feeling the force: how pollen tubes deal with obstacles.

PubMed

Burri, Jan T; Vogler, Hannes; Läubli, Nino F; Hu, Chengzhi; Grossniklaus, Ueli; Nelson, Bradley J

2018-06-15

Physical forces are involved in the regulation of plant development and morphogenesis by translating mechanical stress into the modification of physiological processes, which, in turn, can affect cellular growth. Pollen tubes respond rapidly to external stimuli and provide an ideal system to study the effect of mechanical cues at the single-cell level. Here, pollen tubes were exposed to mechanical stress while monitoring the reconfiguration of their growth and recording the generated forces in real-time. We combined a lab-on-a-chip device with a microelectromechanical systems (MEMS)-based capacitive force sensor to mimic and quantify the forces that are involved in pollen tube navigation upon confronting mechanical obstacles. Several stages of obstacle avoidance were identified, including force perception, growth adjustment and penetration. We have experimentally determined the perceptive force threshold, which is the force threshold at which the pollen tube reacts to an obstacle, for Lilium longiflorum and Arabidopsis thaliana. In addition, the method we developed provides a way to calculate turgor pressure based on force and optical data. Pollen tubes sense physical barriers and actively adjust their growth behavior to overcome them. Furthermore, our system offers an ideal platform to investigate intracellular activity during force perception and growth adaption in tip growing cells. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Hearing loss in children with otitis media with effusion: a systematic review.

PubMed

Cai, Ting; McPherson, Bradley

2017-02-01

Otitis media with effusion (OME) is the presence of non-purulent inflammation in the middle ear. Hearing impairment is frequently associated with OME. Pure tone audiometry and speech audiometry are two of the most primarily utilised auditory assessments and provide valuable behavioural and functional estimation on hearing loss. This paper was designed to review and analyse the effects of the presence of OME on children's listening abilities. A systematic and descriptive review. Twelve articles reporting frequency-specific pure tone thresholds and/or speech perception measures in children with OME were identified using PubMed, Ovid, Web of Science, ProQuest and Google Scholar search platforms. The hearing loss related to OME averages 18-35 dB HL. The air conduction configuration is roughly flat with a slight elevation at 2000 Hz and a nadir at 8000 Hz. Both speech-in-quiet and speech-in-noise perception have been found to be impaired. OME imposes a series of disadvantages on hearing sensitivity and speech perception in children. Further studies investigating the full range of frequency-specific pure tone thresholds, and that adopt standardised speech test materials are advocated to evaluate hearing related disabilities with greater comprehensiveness, comparability and enhanced consideration of their real life implications.

The impact of perilaryngeal vibration on the self-perception of loudness and the Lombard effect.

PubMed

Brajot, François-Xavier; Nguyen, Don; DiGiovanni, Jeffrey; Gracco, Vincent L

2018-04-05

The role of somatosensory feedback in speech and the perception of loudness was assessed in adults without speech or hearing disorders. Participants completed two tasks: loudness magnitude estimation of a short vowel and oral reading of a standard passage. Both tasks were carried out in each of three conditions: no-masking, auditory masking alone, and mixed auditory masking plus vibration of the perilaryngeal area. A Lombard effect was elicited in both masking conditions: speakers unconsciously increased vocal intensity. Perilaryngeal vibration further increased vocal intensity above what was observed for auditory masking alone. Both masking conditions affected fundamental frequency and the first formant frequency as well, but only vibration was associated with a significant change in the second formant frequency. An additional analysis of pure-tone thresholds found no difference in auditory thresholds between masking conditions. Taken together, these findings indicate that perilaryngeal vibration effectively masked somatosensory feedback, resulting in an enhanced Lombard effect (increased vocal intensity) that did not alter speakers' self-perception of loudness. This implies that the Lombard effect results from a general sensorimotor process, rather than from a specific audio-vocal mechanism, and that the conscious self-monitoring of speech intensity is not directly based on either auditory or somatosensory feedback.

Segmental and Suprasegmental Perception in Children Using Hearing Aids.

PubMed

Wenrich, Kaitlyn A; Davidson, Lisa S; Uchanski, Rosalie M

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. American Academy of Audiology

Consumer perception of astringency in clear acidic whey protein beverages.

PubMed

Childs, Jessica L; Drake, MaryAnne

2010-01-01

Acidic whey protein beverages are a growing component of the functional food and beverage market. These beverages are also astringent, but astringency is an expected and desirable attribute of many beverages (red wine, tea, coffee) and may not necessarily be a negative attribute of acidic whey protein beverages. The goal of this study was to define the consumer perception of astringency in clear acidic whey protein beverages. Six focus groups (n=49) were held to gain understanding of consumer knowledge of astringency. Consumers were presented with beverages and asked to map them based on astringent mouthfeel and liking. Orthonasal thresholds for whey protein isolate (WPI) in water and flavored model beverages were determined using a 7-series ascending forced choice method. Mouthfeel/basic taste thresholds were determined for WPI in water. Acceptance tests on model beverages were conducted using consumers (n=120) with and without wearing nose clips. Consumers in focus groups were able to identify astringency in beverages. Astringency intensity was not directly related to dislike. The orthonasal threshold for WPI in water was lower (P < 0.05) than the mouthfeel/basic taste threshold of WPI in water. Consumer acceptance of beverages containing WPI was lower (P < 0.05) when consumers were not wearing nose clips compared to acceptance scores of beverages when consumers were wearing nose clips. These results suggest that flavors contributed by WPI in acidic beverages are more objectionable than the astringent mouthfeel and that both flavor and astringency should be the focus of ongoing studies to improve the palatability of these products. © 2010 Institute of Food Technologists®

Joint Mobilization Enhances Mechanisms of Conditioned Pain Modulation in Individuals With Osteoarthritis of the Knee.

PubMed

Courtney, Carol A; Steffen, Alana D; Fernández-de-Las-Peñas, César; Kim, John; Chmell, Samuel J

2016-03-01

An experimental laboratory study with a repeated-measures crossover design. Treatment effects of joint mobilization may occur in part by decreasing excitability of central nociceptive pathways. Impaired conditioned pain modulation (CPM) has been found experimentally in persons with knee and hip osteoarthritis, indicating impaired inhibition of central nociceptive pathways. We hypothesized increased effectiveness of CPM following application of joint mobilization, determined via measures of deep tissue hyperalgesia. To examine the effect of joint mobilization on impaired CPM. An examination of 40 individuals with moderate/severe knee osteoarthritis identified 29 (73%) with impaired CPM. The subjects were randomized to receive 6 minutes of knee joint mobilization (intervention) or manual cutaneous input only, 1 week apart. Deep tissue hyperalgesia was examined via pressure pain thresholds bilaterally at the knee medial joint line and the hand at baseline, postintervention, and post-CPM testing. Further, vibration perception threshold was measured at the medial knee epicondyle at baseline and post-CPM testing. Joint mobilization, but not cutaneous input intervention, resulted in a global increase in pressure pain threshold, indicated by diminished hyperalgesic responses to pressure stimulus. Further, CPM was significantly enhanced following joint mobilization. Diminished baseline vibration perception threshold acuity was enhanced following joint mobilization at the knee that received intervention, but not at the contralateral knee. Resting pain was also significantly lower following the joint intervention. Conditioned pain modulation was enhanced following joint mobilization, demonstrated by a global decrease in deep tissue pressure sensitivity. Joint mobilization may act via enhancement of descending pain mechanisms in patients with painful knee osteoarthritis.

Effect of laryngotracheal topical anesthesia on recurrent laryngeal nerve monitoring during thyroid Surgery.

PubMed

Pachuski, Justin; Vaida, Sonia; Donahue, Kathleen; Roberts, John; Kunselman, Allen; Oberman, Benjamin; Patel, Hetal; Goldenberg, David

2016-03-01

Intraoperative neuromonitoring of the recurrent laryngeal nerve (RLN) is often used as an adjunct for RLN identification and preservation during thyroidectomies. Laryngotracheal anesthesia (LTA) with topical lidocaine reduces coughing upon emergence from anesthesia and in the immediate postoperative period; however, its use is prohibited with concerns that it could decrease the sensitivity of the intraoperative neuromonitoring. We hypothesize that there is no difference in measurements of nerve conduction made before and after LTA administration. An observational study in which all patients were subjected to LTA administration was conducted. Recurrent laryngeal nerve threshold currents were measured before and after the intervention. Tertiary medical center operating room. Eighteen patients (total of 25 nerves at risk) with American Society of Anesthesiologists classes 1 to 3 undergoing thyroid surgery. After the thyroid was removed and threshold currents at the RLN were obtained, LTA with endotracheal lidocaine was applied on the left and right side of the in situ endotracheal tube (2 cc of 4% lidocaine per side). Threshold currents were reassessed at 5 and 10 minutes after LTA administration. Threshold currents (minimum stimulus current applied to the RLN required to generate a discernible electromyographic response at the vocal cords) were recorded along the RLN for a baseline at 5 and 10 mm from the insertion point of the RLN into the larynx. Threshold currents were reassessed at the same 2 positions on the RLN at 5 and 10 minutes after LTA administration. Differences in mean values, between threshold currents recorded at the 3 different times, at 2 positions on the RLN, were used to compare effects of LTA on nerve conduction. There were no statistically significant differences when comparing threshold currents before and after LTA administration. Laryngotracheal anesthesia had no significant effect on RLN nerve conduction in the period assessed. Copyright © 2016 Elsevier Inc. All rights reserved.

Tinnitus and Auditory Perception After a History of Noise Exposure: Relationship to Auditory Brainstem Response Measures.

PubMed

Bramhall, Naomi F; Konrad-Martin, Dawn; McMillan, Garnett P

2018-01-15

To determine whether auditory brainstem response (ABR) wave I amplitude is associated with measures of auditory perception in young people with normal distortion product otoacoustic emissions (DPOAEs) and varying levels of noise exposure history. Tinnitus, loudness tolerance, and speech perception ability were measured in 31 young military Veterans and 43 non-Veterans (19 to 35 years of age) with normal pure-tone thresholds and DPOAEs. Speech perception was evaluated in quiet using Northwestern University Auditory Test (NU-6) word lists and in background noise using the words in noise (WIN) test. Loudness discomfort levels were measured using 1-, 3-, 4-, and 6-kHz pulsed pure tones. DPOAEs and ABRs were collected in each participant to assess outer hair cell and auditory nerve function. The probability of reporting tinnitus in this sample increased by a factor of 2.0 per 0.1 µV decrease in ABR wave I amplitude (95% Bayesian confidence interval, 1.1 to 5.0) for males and by a factor of 2.2 (95% confidence interval, 1.0 to 6.4) for females after adjusting for sex and DPOAE levels. Similar results were obtained in an alternate model adjusted for pure-tone thresholds in addition to sex and DPOAE levels. No apparent relationship was found between wave I amplitude and either loudness tolerance or speech perception in quiet or noise. Reduced ABR wave I amplitude was associated with an increased risk of tinnitus, even after adjusting for DPOAEs and sex. In contrast, wave III and V amplitudes had little effect on tinnitus risk. This suggests that changes in peripheral input at the level of the inner hair cell or auditory nerve may lead to increases in central gain that give rise to the perception of tinnitus. Although the extent of synaptopathy in the study participants cannot be measured directly, these findings are consistent with the prediction that tinnitus may be a perceptual consequence of cochlear synaptopathy.

Restoring motor control and sensory feedback in people with upper extremity amputations using arrays of 96 microelectrodes implanted in the median and ulnar nerves.

PubMed

Davis, T S; Wark, H A C; Hutchinson, D T; Warren, D J; O'Neill, K; Scheinblum, T; Clark, G A; Normann, R A; Greger, B

2016-06-01

An important goal of neuroprosthetic research is to establish bidirectional communication between the user and new prosthetic limbs that are capable of controlling >20 different movements. One strategy for achieving this goal is to interface the prosthetic limb directly with efferent and afferent fibres in the peripheral nervous system using an array of intrafascicular microelectrodes. This approach would provide access to a large number of independent neural pathways for controlling high degree-of-freedom prosthetic limbs, as well as evoking multiple-complex sensory percepts. Utah Slanted Electrode Arrays (USEAs, 96 recording/stimulating electrodes) were implanted for 30 days into the median (Subject 1-M, 31 years post-amputation) or ulnar (Subject 2-U, 1.5 years post-amputation) nerves of two amputees. Neural activity was recorded during intended movements of the subject's phantom fingers and a linear Kalman filter was used to decode the neural data. Microelectrode stimulation of varying amplitudes and frequencies was delivered via single or multiple electrodes to investigate the number, size and quality of sensory percepts that could be evoked. Device performance over time was assessed by measuring: electrode impedances, signal-to-noise ratios (SNRs), stimulation thresholds, number and stability of evoked percepts. The subjects were able to proportionally, control individual fingers of a virtual robotic hand, with 13 different movements decoded offline (r = 0.48) and two movements decoded online. Electrical stimulation across one USEA evoked >80 sensory percepts. Varying the stimulation parameters modulated percept quality. Devices remained intrafascicularly implanted for the duration of the study with no significant changes in the SNRs or percept thresholds. This study demonstrated that an array of 96 microelectrodes can be implanted into the human peripheral nervous system for up to 1 month durations. Such an array could provide intuitive control of a virtual prosthetic hand with broad sensory feedback.

Restoring motor control and sensory feedback in people with upper extremity amputations using arrays of 96 microelectrodes implanted in the median and ulnar nerves

NASA Astrophysics Data System (ADS)

Davis, T. S.; Wark, H. A. C.; Hutchinson, D. T.; Warren, D. J.; O'Neill, K.; Scheinblum, T.; Clark, G. A.; Normann, R. A.; Greger, B.

2016-06-01

Objective. An important goal of neuroprosthetic research is to establish bidirectional communication between the user and new prosthetic limbs that are capable of controlling >20 different movements. One strategy for achieving this goal is to interface the prosthetic limb directly with efferent and afferent fibres in the peripheral nervous system using an array of intrafascicular microelectrodes. This approach would provide access to a large number of independent neural pathways for controlling high degree-of-freedom prosthetic limbs, as well as evoking multiple-complex sensory percepts. Approach. Utah Slanted Electrode Arrays (USEAs, 96 recording/stimulating electrodes) were implanted for 30 days into the median (Subject 1-M, 31 years post-amputation) or ulnar (Subject 2-U, 1.5 years post-amputation) nerves of two amputees. Neural activity was recorded during intended movements of the subject’s phantom fingers and a linear Kalman filter was used to decode the neural data. Microelectrode stimulation of varying amplitudes and frequencies was delivered via single or multiple electrodes to investigate the number, size and quality of sensory percepts that could be evoked. Device performance over time was assessed by measuring: electrode impedances, signal-to-noise ratios (SNRs), stimulation thresholds, number and stability of evoked percepts. Main results. The subjects were able to proportionally, control individual fingers of a virtual robotic hand, with 13 different movements decoded offline (r = 0.48) and two movements decoded online. Electrical stimulation across one USEA evoked >80 sensory percepts. Varying the stimulation parameters modulated percept quality. Devices remained intrafascicularly implanted for the duration of the study with no significant changes in the SNRs or percept thresholds. Significance. This study demonstrated that an array of 96 microelectrodes can be implanted into the human peripheral nervous system for up to 1 month durations. Such an array could provide intuitive control of a virtual prosthetic hand with broad sensory feedback.

Mismatch negativity (MMN) reveals inefficient auditory ventral stream function in chronic auditory comprehension impairments.

PubMed

Robson, Holly; Cloutman, Lauren; Keidel, James L; Sage, Karen; Drakesmith, Mark; Welbourne, Stephen

2014-10-01

Auditory discrimination is significantly impaired in Wernicke's aphasia (WA) and thought to be causatively related to the language comprehension impairment which characterises the condition. This study used mismatch negativity (MMN) to investigate the neural responses corresponding to successful and impaired auditory discrimination in WA. Behavioural auditory discrimination thresholds of consonant-vowel-consonant (CVC) syllables and pure tones (PTs) were measured in WA (n = 7) and control (n = 7) participants. Threshold results were used to develop multiple deviant MMN oddball paradigms containing deviants which were either perceptibly or non-perceptibly different from the standard stimuli. MMN analysis investigated differences associated with group, condition and perceptibility as well as the relationship between MMN responses and comprehension (within which behavioural auditory discrimination profiles were examined). MMN waveforms were observable to both perceptible and non-perceptible auditory changes. Perceptibility was only distinguished by MMN amplitude in the PT condition. The WA group could be distinguished from controls by an increase in MMN response latency to CVC stimuli change. Correlation analyses displayed a relationship between behavioural CVC discrimination and MMN amplitude in the control group, where greater amplitude corresponded to better discrimination. The WA group displayed the inverse effect; both discrimination accuracy and auditory comprehension scores were reduced with increased MMN amplitude. In the WA group, a further correlation was observed between the lateralisation of MMN response and CVC discrimination accuracy; the greater the bilateral involvement the better the discrimination accuracy. The results from this study provide further evidence for the nature of auditory comprehension impairment in WA and indicate that the auditory discrimination deficit is grounded in a reduced ability to engage in efficient hierarchical processing and the construction of invariant auditory objects. Correlation results suggest that people with chronic WA may rely on an inefficient, noisy right hemisphere auditory stream when attempting to process speech stimuli.

Bodily action penetrates affective perception

PubMed Central

Rigutti, Sara; Gerbino, Walter

2016-01-01

Fantoni & Gerbino (2014) showed that subtle postural shifts associated with reaching can have a strong hedonic impact and affect how actors experience facial expressions of emotion. Using a novel Motor Action Mood Induction Procedure (MAMIP), they found consistent congruency effects in participants who performed a facial emotion identification task after a sequence of visually-guided reaches: a face perceived as neutral in a baseline condition appeared slightly happy after comfortable actions and slightly angry after uncomfortable actions. However, skeptics about the penetrability of perception (Zeimbekis & Raftopoulos, 2015) would consider such evidence insufficient to demonstrate that observer’s internal states induced by action comfort/discomfort affect perception in a top-down fashion. The action-modulated mood might have produced a back-end memory effect capable of affecting post-perceptual and decision processing, but not front-end perception. Here, we present evidence that performing a facial emotion detection (not identification) task after MAMIP exhibits systematic mood-congruent sensitivity changes, rather than response bias changes attributable to cognitive set shifts; i.e., we show that observer’s internal states induced by bodily action can modulate affective perception. The detection threshold for happiness was lower after fifty comfortable than uncomfortable reaches; while the detection threshold for anger was lower after fifty uncomfortable than comfortable reaches. Action valence induced an overall sensitivity improvement in detecting subtle variations of congruent facial expressions (happiness after positive comfortable actions, anger after negative uncomfortable actions), in the absence of significant response bias shifts. Notably, both comfortable and uncomfortable reaches impact sensitivity in an approximately symmetric way relative to a baseline inaction condition. All of these constitute compelling evidence of a genuine top-down effect on perception: specifically, facial expressions of emotion are penetrable by action-induced mood. Affective priming by action valence is a candidate mechanism for the influence of observer’s internal states on properties experienced as phenomenally objective and yet loaded with meaning. PMID:26893964

Ophthalmological assessment of cannabis-induced persisting perception disorder: is there a direct retinal effect?

PubMed

Zobor, Ditta; Strasser, Torsten; Zobor, Gergely; Schober, Franziska; Messias, Andre; Strauss, Olaf; Batra, Anil; Zrenner, Eberhart

2015-04-01

Cannabis is a psychotomimetic agent that induces impairment of sensory perception. We present detailed clinical and electrophysiological data of patients with hallucinogen persisting perception disorder (HPPD) after marijuana consumption. A HPPD patient and four heavy cannabis smokers with no visual disturbances (controls) underwent complete ophthalmological examination including psychophysical tests (visual acuity, color vision, visual field, and dark adaptation) and detailed electrophysiological examinations, including extended Ganzfeld ERG, multifocal ERG, and electrooculography (EOG). Furthermore, electrically evoked phosphene thresholds (EPTs) were measured to further evaluate retinal function. Ophthalmological and most electrophysiological examinations were within normal limits for the HPPD patient and for all control subjects. Interestingly, EOG results of the HPPD patient showed a slightly reduced fast oscillation ratio, diminished standing potentials of the slow oscillations, and a light peak within normal range resulting in higher Arden ratios. The EPTs of the patient were reduced, in particular for pulses with long durations (50 ms) causing visual sensations even at lowest possible currents of the neurostimulator. The control subjects did not reveal such alterations. Our findings suggest a direct effect of cannabinoids on the retina and retinal pigment epithelium function, which may be involved in disturbances of the visual function experienced after drug consumption. The observations presented here may contribute to the elucidation of the detailed mechanism. Furthermore, EOG and EPT measurements may be useful tools to demonstrate long-term retinal alterations in cannabis-induced HPPD in patients.

Which type of leader do I support in step-level public good dilemmas? The roles of level of threshold and trust.

PubMed

De Cremer, David

2007-02-01

The present research examined the moderating effect of the level of threshold on people's preferences for different leader types in step-level public good dilemmas. It was assumed that the primary focus of people in step-level public good dilemmas is to make sure that the group surpasses the threshold. Consequently, when the level of threshold is difficult to reach people are expected to provide more support for and cooperate with a leader that monitors and controls the contributions made toward the public good. However, if the threshold is easy to surpass people will focus more on whether the obtained public good or bonus will be distributed according to agreements, suggesting that people will provide more support to and cooperate with a leader that monitors and controls the distribution of the bonus. These predictions were confirmed across two experiments using a step-level public good paradigm with a dichotomous (Study 1) and a continuous (Study 2) contribution choice. Moreover, the results also revealed that perceptions of trust accounted, in part, for the effect of level of threshold on people's leadership preferences.

Threshold concepts in finance: student perspectives

NASA Astrophysics Data System (ADS)

Hoadley, Susan; Kyng, Tim; Tickle, Leonie; Wood, Leigh N.

2015-10-01

Finance threshold concepts are the essential conceptual knowledge that underpin well-developed financial capabilities and are central to the mastery of finance. In this paper we investigate threshold concepts in finance from the point of view of students, by establishing the extent to which students are aware of threshold concepts identified by finance academics. In addition, we investigate the potential of a framework of different types of knowledge to differentiate the delivery of the finance curriculum and the role of modelling in finance. Our purpose is to identify ways to improve curriculum design and delivery, leading to better student outcomes. Whilst we find that there is significant overlap between what students identify as important in finance and the threshold concepts identified by academics, much of this overlap is expressed by indirect reference to the concepts. Further, whilst different types of knowledge are apparent in the student data, there is evidence that students do not necessarily distinguish conceptual from other types of knowledge. As well as investigating the finance curriculum, the research demonstrates the use of threshold concepts to compare and contrast student and academic perceptions of a discipline and, as such, is of interest to researchers in education and other disciplines.

Influence of aging on thermal and vibratory thresholds of quantitative sensory testing.

PubMed

Lin, Yea-Huey; Hsieh, Song-Chou; Chao, Chi-Chao; Chang, Yang-Chyuan; Hsieh, Sung-Tsang

2005-09-01

Quantitative sensory testing has become a common approach to evaluate thermal and vibratory thresholds in various types of neuropathies. To understand the effect of aging on sensory perception, we measured warm, cold, and vibratory thresholds by performing quantitative sensory testing on a population of 484 normal subjects (175 males and 309 females), aged 48.61 +/- 14.10 (range 20-86) years. Sensory thresholds of the hand and foot were measured with two algorithms: the method of limits (Limits) and the method of level (Level). Thresholds measured by Limits are reaction-time-dependent, while those measured by Level are independent of reaction time. In addition, we explored (1) the correlations of thresholds between these two algorithms, (2) the effect of age on differences in thresholds between algorithms, and (3) differences in sensory thresholds between the two test sites. Age was consistently and significantly correlated with sensory thresholds of all tested modalities measured by both algorithms on multivariate regression analysis compared with other factors, including gender, body height, body weight, and body mass index. When thresholds were plotted against age, slopes differed between sensory thresholds of the hand and those of the foot: for the foot, slopes were steeper compared with those for the hand for each sensory modality. Sensory thresholds of both test sites measured by Level were highly correlated with those measured by Limits, and thresholds measured by Limits were higher than those measured by Level. Differences in sensory thresholds between the two algorithms were also correlated with age: thresholds of the foot were higher than those of the hand for each sensory modality. This difference in thresholds (measured with both Level and Limits) between the hand and foot was also correlated with age. These findings suggest that age is the most significant factor in determining sensory thresholds compared with the other factors of gender and anthropometric parameters, and this provides a foundation for investigating the neurobiologic significance of aging on the processing of sensory stimuli.

A one degree of freedom haptic system to investigate issues in human perception with particular application to probing tissue.

PubMed

Dibble, Edward; Zivanovic, Aleksandar; Davies, Brian

2004-01-01

This paper presents the results of several early studies relating to human haptic perception sensitivity when probing a virtual object. A 1 degree of freedom (DoF) rotary haptic system, that was designed and built for this purpose, is also presented. The experiments were to assess the maximum forces applied in a minimally invasive surgery (MIS) procedure, quantify the compliance sensitivity threshold when probing virtual tissue and identify the haptic system loop rate necessary for haptic feedback to feel realistic.

The effects of visual scenes on roll and pitch thresholds in pilots versus nonpilots.

PubMed

Otakeno, Shinji; Matthews, Roger S J; Folio, Les; Previc, Fred H; Lessard, Charles S

2002-02-01

Previous studies have indicated that, compared with nonpilots, pilots rely more on vision than "seat-of-the-pants" sensations when presented with visual-vestibular conflict. The objective of this study was to evaluate whether pilots and nonpilots differ in their thresholds for tilt perception while viewing visual scenes depicting simulated flight. This study was conducted in the Advanced Spatial Disorientation Demonstrator (ASDD) at Brooks AFB, TX. There were 14 subjects (7 pilots and 7 nonpilots) who recorded tilt detection thresholds in pitch and roll while exposed to sub-threshold movement in each axis. During each test run, subjects were presented with computer-generated visual scenes depicting accelerating forward flight by day or night, and a blank (control) condition. The only significant effect detected by an analysis of variance (ANOVA) was that all subjects were more sensitive to tilt in roll than in pitch [F (2,24) = 18.96, p < 0.001]. Overall, pilots had marginally higher tilt detection thresholds compared with nonpilots (p = 0.055), but the type of visual scene had no significant effect on thresholds. In this study, pilots did not demonstrate greater visual dominance over vestibular and proprioceptive cues than nonpilots, but appeared to have higher pitch and roll thresholds overall. The finding of significantly lower detection thresholds in the roll axis vs. the pitch axis was an incidental finding for both subject groups.

Effects of electrolysis by low-amperage electric current on the chlorophyll fluorescence characteristics of Microcystis aeruginosa.

PubMed

Lin, Li; Feng, Cong; Li, Qingyun; Wu, Min; Zhao, Liangyuan

2015-10-01

Effects of electrolysis by low-amperage electric current on the chlorophyll fluorescence characteristics of Microcystis aeruginosa were investigated in order to reveal the mechanisms of electrolytic inhibition of algae. Threshold of current density was found under a certain initial no. of algae cell. When current density was equal to or higher than the threshold (fixed electrolysis time), growth of algae was inhibited completely and the algae lost the ability to survive. Effect of algal solution volume on algal inhibition was insignificant. Thresholds of current density were 8, 10, 14, 20, and 22 mA cm(-2) at 2.5 × 10(7), 5 × 10(7), 1 × 10(8), 2.5 × 10(8), and 5 × 10(8) cells mL(-1) initial no. of algae cell, respectively. Correlativity between threshold of current and initial no. of algae cells was established for scale-up and determining operating conditions. Changes of chlorophyll fluorescence parameters demonstrated that photosystem (PS) II of algae was damaged by electrolysis but still maintained relatively high activity when algal solution was treated by current densities lower than the threshold. The activity of algae recovered completely after 6 days of cultivation. On the contrary, when current density was higher than the threshold, connection of phycobilisome (PBS) and PS II core complexes was destroyed, PS II system of algae was damaged irreversibly, and algae could not survive thoroughly. The inactivation of M. aeruginosa by electrolysis can be attributed to irreversible separation of PBS from PS II core complexes and the damage of PS II of M. aeruginosa.

Development of the adaptive music perception test.

PubMed

Kirchberger, Martin J; Russo, Frank A

2015-01-01

Despite vast amounts of research examining the influence of hearing loss on speech perception, comparatively little is known about its influence on music perception. No standardized test exists to quantify music perception of hearing-impaired (HI) persons in a clinically practical manner. This study presents the Adaptive Music Perception (AMP) test as a tool to assess important aspects of music perception with hearing loss. A computer-driven test was developed to determine the discrimination thresholds of 10 low-level physical dimensions (e.g., duration, level) in the context of perceptual judgments about musical dimensions: meter, harmony, melody, and timbre. In the meter test, the listener is asked to judge whether a tone sequence is duple or triple in meter. The harmony test requires that the listener make judgments about the stability of the chord sequences. In the melody test, the listener must judge whether a comparison melody is the same as a standard melody when presented in transposition and in the context of a chordal accompaniment that serves as a mask. The timbre test requires that the listener determines which of two comparison tones is different in timbre from a standard tone (ABX design). Twenty-one HI participants and 19 normal-hearing (NH) participants were recruited to carry out the music tests. Participants were tested twice on separate occasions to evaluate test-retest reliability. The HI group had significantly higher discrimination thresholds than the NH group in 7 of the 10 low-level physical dimensions: frequency discrimination in the meter test, dissonance and intonation perception in the harmony test, melody-to-chord ratio for both melody types in the melody test, and the perception of brightness and spectral irregularity in the timbre test. Small but significant improvement between test and retest was observed in three dimensions: frequency discrimination (meter test), dissonance (harmony test), and attack length (timbre test). All other dimensions did not show a session effect. Test-retest reliability was poor (<0.6) for spectral irregularity (timbre test); acceptable (>0.6) for pitch and duration (meter test), dissonance and intonation (harmony test), and melody-to-chord ratio I and II (melody test); and excellent (>0.8) for level (meter test) and attack (timbre test). The AMP test revealed differences in a wide range of music perceptual abilities between NH and HI listeners. The recognition of meter was more difficult for HI listeners when the listening task was based on frequency discrimination. The HI group was less sensitive to changes in harmony and had more difficulties with distinguishing melodies in a background of music. In addition, the thresholds to discriminate timbre were significantly higher for the HI group in brightness and spectral irregularity dimensions. The AMP test can be used as a research tool to further investigate music perception with hearing aids and compare the benefit of different music processing strategies for the HI listener. Future testing will involve larger samples with the inclusion of hearing aided conditions allowing for the establishment of norms so that the test might be appropriate for use in clinical practice.

Determine Optimal Stimulus Amplitude for Using Vestibular Stochastic Stimulation to Improve Balance Function

NASA Technical Reports Server (NTRS)

Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Cohen, H.; Bloomberg, J.J.;

Digital Image Sensor-Based Assessment of the Status of Oat (Avena sativa L.) Crops after Frost Damage

PubMed Central

Macedo-Cruz, Antonia; Pajares, Gonzalo; Santos, Matilde; Villegas-Romero, Isidro

2011-01-01

The aim of this paper is to classify the land covered with oat crops, and the quantification of frost damage on oats, while plants are still in the flowering stage. The images are taken by a digital colour camera CCD-based sensor. Unsupervised classification methods are applied because the plants present different spectral signatures, depending on two main factors: illumination and the affected state. The colour space used in this application is CIELab, based on the decomposition of the colour in three channels, because it is the closest to human colour perception. The histogram of each channel is successively split into regions by thresholding. The best threshold to be applied is automatically obtained as a combination of three thresholding strategies: (a) Otsu’s method, (b) Isodata algorithm, and (c) Fuzzy thresholding. The fusion of these automatic thresholding techniques and the design of the classification strategy are some of the main findings of the paper, which allows an estimation of the damages and a prediction of the oat production. PMID:22163940

Digital image sensor-based assessment of the status of oat (Avena sativa L.) crops after frost damage.

PubMed

Macedo-Cruz, Antonia; Pajares, Gonzalo; Santos, Matilde; Villegas-Romero, Isidro

2011-01-01

The aim of this paper is to classify the land covered with oat crops, and the quantification of frost damage on oats, while plants are still in the flowering stage. The images are taken by a digital colour camera CCD-based sensor. Unsupervised classification methods are applied because the plants present different spectral signatures, depending on two main factors: illumination and the affected state. The colour space used in this application is CIELab, based on the decomposition of the colour in three channels, because it is the closest to human colour perception. The histogram of each channel is successively split into regions by thresholding. The best threshold to be applied is automatically obtained as a combination of three thresholding strategies: (a) Otsu's method, (b) Isodata algorithm, and (c) Fuzzy thresholding. The fusion of these automatic thresholding techniques and the design of the classification strategy are some of the main findings of the paper, which allows an estimation of the damages and a prediction of the oat production.

Carbon deposition thresholds on nickel-based solid oxide fuel cell anodes II. Steam:carbon ratio and current density

NASA Astrophysics Data System (ADS)

Kuhn, J.; Kesler, O.

2015-03-01

For the second part of a two part publication, coking thresholds with respect to molar steam:carbon ratio (SC) and current density in nickel-based solid oxide fuel cells were determined. Anode-supported button cell samples were exposed to 2-component and 5-component gas mixtures with 1 ≤ SC ≤ 2 and zero fuel utilization for 10 h, followed by measurement of the resulting carbon mass. The effect of current density was explored by measuring carbon mass under conditions known to be prone to coking while increasing the current density until the cell was carbon-free. The SC coking thresholds were measured to be ∼1.04 and ∼1.18 at 600 and 700 °C, respectively. Current density experiments validated the thresholds measured with respect to fuel utilization and steam:carbon ratio. Coking thresholds at 600 °C could be predicted with thermodynamic equilibrium calculations when the Gibbs free energy of carbon was appropriately modified. Here, the Gibbs free energy of carbon on nickel-based anode support cermets was measured to be -6.91 ± 0.08 kJ mol-1. The results of this two part publication show that thermodynamic equilibrium calculations with appropriate modification to the Gibbs free energy of solid-phase carbon can be used to predict coking thresholds on nickel-based anodes at 600-700 °C.

Spatially restricted electrical activation of retinal ganglion cells in the rabbit retina by hexapolar electrode return configuration

NASA Astrophysics Data System (ADS)

Habib, Amgad G.; Cameron, Morven A.; Suaning, Gregg J.; Lovell, Nigel H.; Morley, John W.

2013-06-01

Objective. Visual prostheses currently in development aim to restore some form of vision to patients suffering from diseases such as age-related macular degeneration and retinitis pigmentosa. Most rely on electrically stimulating inner retinal cells via electrodes implanted on or near the retina, resulting in percepts of light termed ‘phosphenes’. Activation of spatially distinct populations of cells in the retina is key for pattern vision to be produced. To achieve this, the electrical stimulation must be localized, activating cells only in the direct vicinity of the stimulating electrode(s). With this goal in mind, a hexagonal return (hexapolar) configuration has been proposed as an alternative to the traditional monopolar or bipolar return configurations for electrically stimulating the retina. This study investigated the efficacy of the hexapolar configuration in localizing the activation of retinal ganglion cells (RGCs), compared to a monopolar configuration. Approach. Patch-clamp electrophysiology was used to measure the activation thresholds of RGCs in whole-mount rabbit retina to monopolar and hexapolar electrical stimulation, applied subretinally. Main results. Hexapolar activation thresholds for RGCs located outside the hex guard were found to be significantly (>2 fold) higher than those located inside the area of tissue bounded by the hex guard. The hexapolar configuration localized the activation of RGCs more effectively than its monopolar counterpart. Furthermore, no difference in hexapolar thresholds or localization was observed when using cathodic-first versus anodic-first stimulation. Significance. The hexapolar configuration may provide an improved method for electrically stimulating spatially distinct populations of cells in retinal tissue.

Virtual Acoustics: Evaluation of Psychoacoustic Parameters

NASA Technical Reports Server (NTRS)

Begault, Durand R.; Null, Cynthia H. (Technical Monitor)

1997-01-01

Current virtual acoustic displays for teleconferencing and virtual reality are usually limited to very simple or non-existent renderings of reverberation, a fundamental part of the acoustic environmental context that is encountered in day-to-day hearing. Several research efforts have produced results that suggest that environmental cues dramatically improve perceptual performance within virtual acoustic displays, and that is possible to manipulate signal processing parameters to effectively reproduce important aspects of virtual acoustic perception in real-time. However, the computational resources for rendering reverberation remain formidable. Our efforts at NASA Ames have been focused using a several perceptual threshold metrics, to determine how various "trade-offs" might be made in real-time acoustic rendering. This includes both original work and confirmation of existing data that was obtained in real rather than virtual environments. The talk will consider the importance of using individualized versus generalized pinnae cues (the "Head-Related Transfer Function"); the use of head movement cues; threshold data for early reflections and late reverberation; and consideration of the necessary accuracy for measuring and rendering octave-band absorption characteristics of various wall surfaces. In addition, a consideration of the analysis-synthesis of the reverberation within "everyday spaces" (offices, conference rooms) will be contrasted to the commonly used paradigm of concert hall spaces.

Relationship between channel interaction and spectral-ripple discrimination in cochlear implant usersa

PubMed Central

Jones, Gary L.; Ho Won, Jong; Drennan, Ward R.; Rubinstein, Jay T.

2013-01-01

Cochlear implant (CI) users can achieve remarkable speech understanding, but there is great variability in outcomes that is only partially accounted for by age, residual hearing, and duration of deafness. Results might be improved with the use of psychophysical tests to predict which sound processing strategies offer the best potential outcomes. In particular, the spectral-ripple discrimination test offers a time-efficient, nonlinguistic measure that is correlated with perception of both speech and music by CI users. Features that make this “one-point” test time-efficient, and thus potentially clinically useful, are also connected to controversy within the CI field about what the test measures. The current work examined the relationship between thresholds in the one-point spectral-ripple test, in which stimuli are presented acoustically, and interaction indices measured under the controlled conditions afforded by direct stimulation with a research processor. Results of these studies include the following: (1) within individual subjects there were large variations in the interaction index along the electrode array, (2) interaction indices generally decreased with increasing electrode separation, and (3) spectral-ripple discrimination improved with decreasing mean interaction index at electrode separations of one, three, and five electrodes. These results indicate that spectral-ripple discrimination thresholds can provide a useful metric of the spectral resolution of CI users. PMID:23297914

Development of a commercially viable piezoelectric force sensor system for static force measurement

NASA Astrophysics Data System (ADS)

Liu, Jun; Luo, Xinwei; Liu, Jingcheng; Li, Min; Qin, Lan

2017-09-01

A compensation method for measuring static force with a commercial piezoelectric force sensor is proposed to disprove the theory that piezoelectric sensors and generators can only operate under dynamic force. After studying the model of the piezoelectric force sensor measurement system, the principle of static force measurement using a piezoelectric material or piezoelectric force sensor is analyzed. Then, the distribution law of the decay time constant of the measurement system and the variation law of the measurement system’s output are studied, and a compensation method based on the time interval threshold Δ t and attenuation threshold Δ {{u}th} is proposed. By calibrating the system and considering the influences of the environment and the hardware, a suitable Δ {{u}th} value is determined, and the system’s output attenuation is compensated based on the Δ {{u}th} value to realize the measurement. Finally, a static force measurement system with a piezoelectric force sensor is developed based on the compensation method. The experimental results confirm the successful development of a simple compensation method for static force measurement with a commercial piezoelectric force sensor. In addition, it is established that, contrary to the current perception, a piezoelectric force sensor system can be used to measure static force through further calibration.

Relationship between channel interaction and spectral-ripple discrimination in cochlear implant users.

PubMed

Jones, Gary L; Won, Jong Ho; Drennan, Ward R; Rubinstein, Jay T

2013-01-01

Cochlear implant (CI) users can achieve remarkable speech understanding, but there is great variability in outcomes that is only partially accounted for by age, residual hearing, and duration of deafness. Results might be improved with the use of psychophysical tests to predict which sound processing strategies offer the best potential outcomes. In particular, the spectral-ripple discrimination test offers a time-efficient, nonlinguistic measure that is correlated with perception of both speech and music by CI users. Features that make this "one-point" test time-efficient, and thus potentially clinically useful, are also connected to controversy within the CI field about what the test measures. The current work examined the relationship between thresholds in the one-point spectral-ripple test, in which stimuli are presented acoustically, and interaction indices measured under the controlled conditions afforded by direct stimulation with a research processor. Results of these studies include the following: (1) within individual subjects there were large variations in the interaction index along the electrode array, (2) interaction indices generally decreased with increasing electrode separation, and (3) spectral-ripple discrimination improved with decreasing mean interaction index at electrode separations of one, three, and five electrodes. These results indicate that spectral-ripple discrimination thresholds can provide a useful metric of the spectral resolution of CI users.

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Injection lasers based on the AlGaAsSb system emitting at 1.6 μm

NASA Astrophysics Data System (ADS)

Virro, A. L.; Eliseev, P. G.; Lyuk, P. A.; Fridental, Ya K.; Khaller, Yu E.

1988-11-01

An experimental dependence of the threshold current density jth on the thickness of the active region was used to find the reduced threshold current density for AlGaAsSb (λ = 1.59μm, T = 295K) lasers: this density was 8 kA·cm-2·μm-1. The minimum threshold current was jth = 1.8 kA/cm2. Wide-contact lasers exhibited cw operation down to 175 K.

Threshold current for fireball generation

NASA Astrophysics Data System (ADS)

Dijkhuis, Geert C.

1982-05-01

Fireball generation from a high-intensity circuit breaker arc is interpreted here as a quantum-mechanical phenomenon caused by severe cooling of electrode material evaporating from contact surfaces. According to the proposed mechanism, quantum effects appear in the arc plasma when the radius of one magnetic flux quantum inside solid electrode material has shrunk to one London penetration length. A formula derived for the threshold discharge current preceding fireball generation is found compatible with data reported by Silberg. This formula predicts linear scaling of the threshold current with the circuit breaker's electrode radius and concentration of conduction electrons.

Global motion perception is related to motor function in 4.5-year-old children born at risk of abnormal development.

PubMed

Chakraborty, Arijit; Anstice, Nicola S; Jacobs, Robert J; Paudel, Nabin; LaGasse, Linda L; Lester, Barry M; McKinlay, Christopher J D; Harding, Jane E; Wouldes, Trecia A; Thompson, Benjamin

2017-06-01

Global motion perception is often used as an index of dorsal visual stream function in neurodevelopmental studies. However, the relationship between global motion perception and visuomotor control, a primary function of the dorsal stream, is unclear. We measured global motion perception (motion coherence threshold; MCT) and performance on standardized measures of motor function in 606 4.5-year-old children born at risk of abnormal neurodevelopment. Visual acuity, stereoacuity and verbal IQ were also assessed. After adjustment for verbal IQ or both visual acuity and stereoacuity, MCT was modestly, but significantly, associated with all components of motor function with the exception of fine motor scores. In a separate analysis, stereoacuity, but not visual acuity, was significantly associated with both gross and fine motor scores. These results indicate that the development of motion perception and stereoacuity are associated with motor function in pre-school children. Copyright © 2017 Elsevier Ltd. All rights reserved.

A short note on the inclusion of sultriness issues in perceived temperature in mild climates

NASA Astrophysics Data System (ADS)

Staiger, Henning; Laschewski, Gudrun; Matzarakis, Andreas

2018-01-01

Sultriness is a specific case in thermal perception under warm/humid environments and frequently applied in German operational weather forecast and is assumed if the dew-point temperature t d exceeds a threshold of 16.5 °C. In perceived temperature ( PT), which is based on the ASHRAE two-node-model, a Central European climatology was prepared of the classical predicted mean vote ( PMV), exclusively linked to thermal stress, and the so-called rational PMV* that additionally accounts for the humidity in the meteorological environment and is closely linked to thermal strain. The standard deviation of the difference Δ PMV = PMV* - PMV over PMV reveals a similarity to the appearance of sultriness that suggests as side effect of the PT parameterisation a thermophysiologically based definition of sultriness: "Under warm/humid conditions a subject adapted to mild climatologic conditions perceives sultriness if the actual value of Δ PMV exceeds the long-term mean by more than its single standard deviation". This definition accounts for all environmental and subject related variables influencing the thermal state of the body and is in accordance with all in the literature described properties in the perception of sultriness. The two definitions coincide more or less at daylight hours for t d values markedly beyond the threshold. However, in the t d threshold region, the PT-derived definition offers stronger differentiated patterns and is significantly less frequent at nighttime than the mono-causal definition. For given PT values, the sensible heat flux via the skin shows an increase under a sultry environment, whereas the latent is reduced; skin and core temperatures as well as the skin blood flow are also less. In any case, PT-derived sultriness is linked with an increased thermal strain on the body temperatures, which is a measure of discomfort caused by increased humidity and/or dissatisfaction with the thermal environment. This confirms the thermal uncomfortable feeling accompanying the perception of sultriness. Therefore, the PT-derived sultriness can be presumed to be a more appropriate measure for the perception of sultriness, because it accounts for all environmental impacts on thermoregulation.

High efficiency low threshold current 1.3 μm InAs quantum dot lasers on on-axis (001) GaP/Si

NASA Astrophysics Data System (ADS)

Jung, Daehwan; Norman, Justin; Kennedy, M. J.; Shang, Chen; Shin, Bongki; Wan, Yating; Gossard, Arthur C.; Bowers, John E.

2017-09-01

We demonstrate highly efficient, low threshold InAs quantum dot lasers epitaxially grown on on-axis (001) GaP/Si substrates using molecular beam epitaxy. Electron channeling contrast imaging measurements show a threading dislocation density of 7.3 × 106 cm-2 from an optimized GaAs template grown on GaP/Si. The high-quality GaAs templates enable as-cleaved quantum dot lasers to achieve a room-temperature continuous-wave (CW) threshold current of 9.5 mA, a threshold current density as low as 132 A/cm2, a single-side output power of 175 mW, and a wall-plug-efficiency of 38.4% at room temperature. As-cleaved QD lasers show ground-state CW lasing up to 80 °C. The application of a 95% high-reflectivity coating on one laser facet results in a CW threshold current of 6.7 mA, which is a record-low value for any kind of Fabry-Perot laser grown on Si.

Correlations among within-channel and between-channel auditory gap-detection thresholds in normal listeners.

PubMed

Phillips, Dennis P; Smith, Jennifer C

2004-01-01

We obtained data on within-channel and between-channel auditory temporal gap-detection acuity in the normal population. Ninety-five normal listeners were tested for gap-detection thresholds, for conditions in which the gap was bounded by spectrally identical, and by spectrally different, acoustic markers. Separate thresholds were obtained with the use of an adaptive tracking method, for gaps delimited by narrowband noise bursts centred on 1.0 kHz, noise bursts centred on 4.0 kHz, and for gaps bounded by a leading marker of 4.0 kHz noise and a trailing marker of 1.0 kHz noise. Gap thresholds were lowest for silent periods bounded by identical markers--'within-channel' stimuli. Gap thresholds were significantly longer for the between-channel stimulus--silent periods bounded by unidentical markers (p < 0.0001). Thresholds for the two within-channel tasks were highly correlated (R = 0.76). Thresholds for the between-channel stimulus were weakly correlated with thresholds for the within-channel stimuli (1.0 kHz, R = 0.39; and 4.0 kHz, R = 0.46). The relatively poor predictability of between-channel thresholds from the within-channel thresholds is new evidence on the separability of the mechanisms that mediate performance of the two tasks. The data confirm that the acuity difference for the tasks, which has previously been demonstrated in only small numbers of highly trained listeners, extends to a population of untrained listeners. The acuity of the between-channel mechanism may be relevant to the formation of voice-onset time-category boundaries in speech perception.

InAs-based interband-cascade-lasers emitting around 7 μm with threshold current densities below 1 kA/cm{sup 2} at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dallner, Matthias; Hau, Florian; Kamp, Martin

2015-01-26

Interband cascade lasers (ICLs) grown on InAs substrates with threshold current densities below 1 kA/cm{sup 2} are presented. Two cascade designs with different lengths of the electron injector were investigated. Using a cascade design with 3 InAs quantum wells (QWs) in the electron injector, a device incorporating 22 stages in the active region exhibited a threshold current density of 940 A/cm{sup 2} at a record wavelength of 7 μm for ICLs operating in pulsed mode at room temperature. By investigating the influence of the number of stages on the device performance for a cascade design with 2 QWs in the electron injector, amore » further reduction of the threshold current density to 800 A/cm{sup 2} was achieved for a 30 stage device.« less

Ultralow threshold graded-index separate-confinement heterostructure single quantum well (Al, Ga) As lasers

NASA Technical Reports Server (NTRS)

Derry, P. L.; Chen, H. Z.; Morkoc, H.; Yariv, A.; Lau, K. Y.

1988-01-01

Broad area graded-index separate-confinement heterostructure single quantum well lasers grown by molecular-beam epitaxy (MBE) with threshold current density as low as 93 A/sq cm (520 microns long) have been fabricated. Buried lasers formed from similarly structured MBE material with liquid phase epitaxy regrowth had threshold currents at submilliampere levels when high reflectivity coatings were applied to the end facets. A CW threshold current of 0.55 mA was obtained for a laser with facet reflectivities of about 80 percent, a cavity length of 120 micron, and an active region stripe width of 1 micron. These devices driven directly with logic level signals have switch-on delays less than 50 ps without any current prebias. Such lasers permit fully on-off switching while at the same time obviating the need for bias monitoring and feedback control.

[Speech perception with electric-acoustic stimulation : Comparison with bilateral cochlear implant users in different noise conditions].

PubMed

Rader, T

2015-02-01

Cochlear implantation with the aim of hearing preservation for combined electric-acoustic stimulation (EAS) is the therapy of choice for patients with residual low-frequency hearing. Preserved residual acoustic hearing has a positive effect on speech intelligibility in difficult noise conditions. The goal of this study was to assess speech reception thresholds in various complex noise conditions for patients with EAS in comparison with patients using bilateral cochlear implants (CI). Speech perception in noise was measured for bilateral CI and EAS patient groups. A total of 22 listeners with normal hearing served as a control group. Speech reception thresholds (SRT) were measured using a closed-set sentence matrix test. Speech was presented with a single source in frontal position; noise was presented in frontal position or in a multisource noise field (MSNF) consisting of a four-loudspeaker array with independent noise sources. Modulated speech-simulating noise and pseudocontinuous noise served respectively as interference signal with different temporal characteristics. The average SRTs in the EAS group were significantly better in all test conditions than those of the group with bilateral CI. Both user groups showed significant improvement in the MSNF condition compared with the frontal noise condition as a result of bilateral interaction. The normal-hearing control group was able to use short temporal gaps in modulated noise to improve speech perception in noise (gap listening). This effect was absent in both implanted user groups. Patients with combined EAS in one ear and a hearing aid in the contralateral ear show significantly improved speech perception in complex noise conditions compared with bilateral CI recipients.

Tactile Perception in Adults with Autism: A Multidimensional Psychophysical Study

ERIC Educational Resources Information Center

Cascio, Carissa; McGlone, Francis; Folger, Stephen; Tannan, Vinay; Baranek, Grace; Pelphrey, Kevin A.; Essick, Gregory

2008-01-01

Although sensory problems, including unusual tactile sensitivity, are heavily associated with autism, there is a dearth of rigorous psychophysical research. We compared tactile sensation in adults with autism to controls on the palm and forearm, the latter innervated by low-threshold unmyelinated afferents subserving a social/affiliative…

PERCEPTION OF ODOR AND NASAL PUNGENCY FROM HOMOLOGOUS SERIES OF VOLATILE ORGANIC COMPOUNDS

EPA Science Inventory

The paper discusses results of tests of nasal detection thresholds for airborne chemicals in a group of anosmics (i.e., subjects lacking a functional sense of smell) and in a group of age-, gender-, and smoking-status-matched normosmics (i.e., subjects with normal olfaction). Ano...

Active-Matrix Organic Light Emission Diode Pixel Circuit for Suppressing and Compensating for the Threshold Voltage Degradation of Hydrogenated Amorphous Silicon Thin Film Transistors

NASA Astrophysics Data System (ADS)

Shin, Hee-Sun; Lee, Won-Kyu; Park, Sang-Guen; Kuk, Seung-Hee; Han, Min-Koo

2009-03-01

A new hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) pixel circuit for active-matrix organic light emission diodes (AM-OLEDs), which significantly compensates the OLED current degradation by memorizing the threshold voltage of driving TFT and suppresses the threshold voltage shift of a-Si:H TFTs by negative bias annealing, is proposed and fabricated. During the first half of each frame, the driving TFT of the proposed pixel circuit supplies current to the OLED, which is determined by modified data voltage in the compensation scheme. The proposed pixel circuit was able to compensate the threshold voltage shift of the driving TFT as well as the OLED. During the remaining half of each frame, the proposed pixel circuit induces the recovery of the threshold voltage degradation of a-Si:H TFTs owing to the negative bias annealing. The experimental results show that the proposed pixel circuit was able to successfully compensate for the OLED current degradation and suppress the threshold voltage degradation of the driving TFT.

Direction detection thresholds of passive self-motion in artistic gymnasts.

PubMed

Hartmann, Matthias; Haller, Katia; Moser, Ivan; Hossner, Ernst-Joachim; Mast, Fred W

2014-04-01

In this study, we compared direction detection thresholds of passive self-motion in the dark between artistic gymnasts and controls. Twenty-four professional female artistic gymnasts (ranging from 7 to 20 years) and age-matched controls were seated on a motion platform and asked to discriminate the direction of angular (yaw, pitch, roll) and linear (leftward-rightward) motion. Gymnasts showed lower thresholds for the linear leftward-rightward motion. Interestingly, there was no difference for the angular motions. These results show that the outstanding self-motion abilities in artistic gymnasts are not related to an overall higher sensitivity in self-motion perception. With respect to vestibular processing, our results suggest that gymnastic expertise is exclusively linked to superior interpretation of otolith signals when no change in canal signals is present. In addition, thresholds were overall lower for the older (14-20 years) than for the younger (7-13 years) participants, indicating the maturation of vestibular sensitivity from childhood to adolescence.

Auditory Processing in Specific Language Impairment (SLI): Relations With the Perception of Lexical and Phrasal Stress.

PubMed

Richards, Susan; Goswami, Usha

2015-08-01

We investigated whether impaired acoustic processing is a factor in developmental language disorders. The amplitude envelope of the speech signal is known to be important in language processing. We examined whether impaired perception of amplitude envelope rise time is related to impaired perception of lexical and phrasal stress in children with specific language impairment (SLI). Twenty-two children aged between 8 and 12 years participated in this study. Twelve had SLI; 10 were typically developing controls. All children completed psychoacoustic tasks measuring rise time, intensity, frequency, and duration discrimination. They also completed 2 linguistic stress tasks measuring lexical and phrasal stress perception. The SLI group scored significantly below the typically developing controls on both stress perception tasks. Performance on stress tasks correlated with individual differences in auditory sensitivity. Rise time and frequency thresholds accounted for the most unique variance. Digit Span also contributed to task success for the SLI group. The SLI group had difficulties with both acoustic and stress perception tasks. Our data suggest that poor sensitivity to amplitude rise time and sound frequency significantly contributes to the stress perception skills of children with SLI. Other cognitive factors such as phonological memory are also implicated.

Mouse current vocalization threshold measured with a neurospecific nociception assay: The effect of sex, morphine, and isoflurane

PubMed Central

Spornick, Nicholas; Guptill, Virginia; Koziol, Deloris; Wesley, Robert; Finkel, Julia; Quezado, Zenaide M.N.

2012-01-01

Sine-wave electrical stimulation at frequencies 2000, 250, and 5 Hz to respectively evaluate Aβ, Aδ, and C sensory neurons has recently been added to the armamentarium used to evaluate sensory neurons. We developed an automated nociception assay using sine-wave stimulation methodology to determine current vocalization threshold in response to 2000, 250, and 5 Hz and examine the effects of sex, analgesics, and anesthetics in mice. At baseline, males had significantly higher mean current vocalization thresholds compared with female mice at 2000, 250, and 5 Hz (p ≤ 0.019). By 1 h after intrathecal injections of morphine there were significant increases in current vocalization threshold percent changes from baseline that varied with doses (p = 0.0001) and frequency used (p < 0.0001). Specifically, with increasing doses of morphine, there were significantly greater increases in current vocalization threshold percent changes from baseline in response to 5 Hz compared with 250 and 2000 Hz stimulation in a significantly ordered pattern: 5 Hz > 250 Hz (p < 0.0001) and 250 Hz > 2000 Hz (p = 0.0002). Forty-five minutes after exposure, there were no effects of isoflurane on current vocalization thresholds at any frequency. Therefore, our findings suggest that this automated nociception assay using sine-wave stimulation in mice, can be valuable for measurements of the effects of sex, opioids, and anesthetics on the response to electrical stimuli that preferentially stimulate Aβ, Aδ, and C-sensory fibers in vivo. This investigation suggests the validation of this assay and supports its use to examine mechanisms of nociception in mice. PMID:21864576

Auditory brainstem response to complex sounds predicts self-reported speech-in-noise performance.

PubMed

Anderson, Samira; Parbery-Clark, Alexandra; White-Schwoch, Travis; Kraus, Nina

2013-02-01

To compare the ability of the auditory brainstem response to complex sounds (cABR) to predict subjective ratings of speech understanding in noise on the Speech, Spatial, and Qualities of Hearing Scale (SSQ; Gatehouse & Noble, 2004) relative to the predictive ability of the Quick Speech-in-Noise test (QuickSIN; Killion, Niquette, Gudmundsen, Revit, & Banerjee, 2004) and pure-tone hearing thresholds. Participants included 111 middle- to older-age adults (range = 45-78) with audiometric configurations ranging from normal hearing levels to moderate sensorineural hearing loss. In addition to using audiometric testing, the authors also used such evaluation measures as the QuickSIN, the SSQ, and the cABR. Multiple linear regression analysis indicated that the inclusion of brainstem variables in a model with QuickSIN, hearing thresholds, and age accounted for 30% of the variance in the Speech subtest of the SSQ, compared with significantly less variance (19%) when brainstem variables were not included. The authors' results demonstrate the cABR's efficacy for predicting self-reported speech-in-noise perception difficulties. The fact that the cABR predicts more variance in self-reported speech-in-noise (SIN) perception than either the QuickSIN or hearing thresholds indicates that the cABR provides additional insight into an individual's ability to hear in background noise. In addition, the findings underscore the link between the cABR and hearing in noise.

Investigations into haptic space and haptic perception of shape for active touch

NASA Astrophysics Data System (ADS)

Sanders, A. F. J.

2008-12-01

This thesis presents a number of psychophysical investigations into haptic space and haptic perception of shape. Haptic perception is understood to include the two subsystems of the cutaneous sense and kinesthesis. Chapter 2 provides an extensive quantitative study into haptic perception of curvature. I investigated bimanual curvature discrimination of cylindrically curved, hand-sized surfaces. I found that discrimination thresholds were in the same range as unimanual thresholds reported in previous studies. Moreover, the distance between the surfaces or the position of the setup with respect to the observer had no effect on thresholds. Finally, I found idiosyncratic biases: A number of observers judged two surfaces that had different radii as equally curved. Biases were of the same order of magnitude as thresholds. In Chapter 3, I investigated haptic space. Here, haptic space is understood to be (1) the set of observer’s judgments of spatial relations in physical space, and (2) a set of constraints by which these judgments are internally consistent. I asked blindfolded observers to construct straight lines in a number of different tasks. I show that the shape of the haptically straight line depends on the task used to produce it. I therefore conclude that there is no unique definition of the haptically straight line and that doubts are cast on the usefulness of the concept of haptic space. In Chapter 4, I present a new experiment into haptic length perception. I show that when observers trace curved pathways with their index finger and judge distance traversed, their distance estimates depend on the geometry of the paths: Lengths of convex, cylindrically curved pathways were overestimated and lengths of concave pathways were underestimated. In addition, I show that a kinematic mechanism must underlie this interaction: (1) the geometry of the path traced by the finger affects movement speed and consequently movement time, and (2) movement time is taken as a measure of traversed length. The study presented in Chapter 5 addresses the question of how kinematic properties of exploratory movements affect perceived shape. I identify a kinematic invariant for the case of a single finger moving across cylindrically curved strips under conditions of slip. I found that the rotation angle of the finger increased linearly with the curvature of the stimulus. In addition, I show that observers took rotation angle as their primary measure of perceived curvature: Observers rotated their finger less on a concave curvature by a constant amount, and consequently, they overestimated the radius of the concave strips compared to the convex ones. Finally, in Chapter 6, I investigated the haptic filled-space illusion for dynamic touch: Observers move their fingertip across an unfilled extent or an extent filled with intermediate stimulations. Previous researchers have reported lengths of filled extents to be overestimated, but the parameters affecting the strength of the illusion are still largely unknown. Factors investigated in this chapter include end point effects, filler density and overall average movement speed.

Psychophysical and Patient Factors as Determinants of Pain, Function and Health Status in Shoulder Disorders

PubMed Central

Uddin, Zakir; MacDermid, Joy C.; Moro, Jaydeep; Galea, Victoria; Gross, Anita R.

2016-01-01

Objective: To estimate the extent to which psychophysical quantitative sensory test (QST) and patient factors (gender, age and comorbidity) predict pain, function and health status in people with shoulder disorders. To determine if there are gender differences for QST measures in current perception threshold (CPT), vibration threshold (VT) and pressure pain (PP) threshold and tolerance. Design: A cross-sectional study design. Setting: MacHAND Clinical Research Lab at McMaster University. Subjects: 34 surgical and 10 nonsurgical participants with shoulder pain were recruited. Method: Participants completed the following patient reported outcomes: pain (Numeric Pain Rating, Pain Catastrophizing Scale, Shoulder Pain and Disability Index) and health status (Short Form-12). Participants completed QST at 4 standardized locations and then an upper extremity performance-based endurance test (FIT-HaNSA). Pearson r’s were computed to determine the relationships between QST variables and patient factors with either pain, function or health status. Eight regression models were built to analysis QST’s and patient factors separately as predictors of either pain, function or health status. An independent sample t-test was done to evaluate the gender effect on QST. Results: Greater PP threshold and PP tolerance was significantly correlated with higher shoulder functional performance on the FIT-HANSA (r =0.31-0.44) and lower self-reported shoulder disability (r = -0.32 to -0.36). Higher comorbidity was consistently correlated (r =0.31-0.46) with more pain, and less function and health status. Older age was correlated to more pain intensity and less function (r =0.31-0.57). In multivariate models, patient factors contributed significantly to pain, function or health status models (r2 =0.19-0.36); whereas QST did not. QST was significantly different between males and females [in PP threshold (3.9 vs. 6.2, p < .001) and PP tolerance (7.6 vs. 2.6, p < .001) and CPT (1.6 vs. 2.3, p =.02)]. Conclusion: Psychophysical dimensions and patient factors (gender, age and comorbidity) affect self-reported and performance-based outcome measures in people with shoulder disorders. PMID:29399220

Northeast Tennessee Educators' Perception of STEM Education Implementation

ERIC Educational Resources Information Center

Turner, Kristin Beard

2013-01-01

A quantitative nonexperimental survey study was developed to investigate Northeast Tennessee K-8 educators' perceptions of STEM education. This study was an examination of current perceptions of STEM education. Perceived need, current implementation practices, access to STEM resources, definition of STEM, and the current condition of STEM in…

A THRESHOLD ANALYSIS OF THE TUNNEL INJECTION LASER.

DTIC Science & Technology

A new threshold analysis of the tunnel injection laser is given that differs from previous treatments in that an additional loss mechanism is...a slight increase in the threshold current density of the tunnel laser. For a device one millimeter long composed of GaAs at 77K, the threshold

Preserved subliminal processing and impaired conscious access in schizophrenia

PubMed Central

Del Cul, Antoine; Dehaene, Stanislas; Leboyer, Marion

2006-01-01

Background Studies of visual backward masking have frequently revealed an elevated masking threshold in schizophrenia. This finding has frequently been interpreted as indicating a low-level visual deficit. However, more recent models suggest that masking may also involve late and higher-level integrative processes, while leaving intact early “bottom-up” visual processing. Objectives We tested the hypothesis that the backward masking deficit in schizophrenia corresponds to a deficit in the late stages of conscious perception, whereas the subliminal processing of masked stimuli is fully preserved. Method 28 patients with schizophrenia and 28 normal controls performed two backward-masking experiments. We used Arabic digits as stimuli and varied quasi-continuously the interval with a subsequent mask, thus allowing us to progressively “unmask” the stimuli. We finely quantified their degree of visibility using both objective and subjective measures to evaluate the threshold duration for access to consciousness. We also studied the priming effect caused by the variably masked numbers on a comparison task performed on a subsequently presented and highly visible target number. Results The threshold delay between digit and mask necessary for the conscious perception of the masked stimulus was longer in patients compared to control subjects. This higher consciousness threshold in patients was confirmed by an objective and a subjective measure, and both measures were highly correlated for patients as well as for controls. However, subliminal priming of masked numbers was effective and identical in patients compared to controls. Conclusions Access to conscious report of masked stimuli is impaired in schizophrenia, while fast bottom-up processing of the same stimuli, as assessed by subliminal priming, is preserved. These findings suggest a high-level origin of the masking deficit in schizophrenia, although they leave open for further research its exact relation to previously identified bottom-up visual processing abnormalities. PMID:17146006

Analysis of retinal function using chromatic pupillography in retinitis pigmentosa and the relationship to electrically evoked phosphene thresholds.

PubMed

Kelbsch, Carina; Maeda, Fumiatsu; Lisowska, Jolanta; Lisowski, Lukasz; Strasser, Torsten; Stingl, Krunoslav; Wilhelm, Barbara; Wilhelm, Helmut; Peters, Tobias

2017-06-01

To analyse pupil responses to specific chromatic stimuli in patients with advanced retinitis pigmentosa (RP) to ascertain whether chromatic pupillography can be used as an objective marker for residual retinal function. To examine correlations between parameters of the pupil response and the perception threshold of electrically evoked phosphenes. Chromatic pupillography was performed in 40 patients with advanced RP (visual acuity < 0.02 or visual field ≤5°, non-recordable ERGs) and 40 age-matched healthy subjects. Pupil responses to full-field red (605 nm) and blue (420 nm) stimuli of 28 lx corneal illumination were recorded and analysed for two stimulus durations (1 and 4 seconds). The perception threshold of phosphenes to transcorneal electrostimulation was ascertained and correlated to the pupil responses and visual acuity. Patients with RP showed significantly reduced pupil responses to red and blue stimuli compared with the controls. With red stimuli, pupillary escape could be observed; blue stimuli resulted in a well-preserved postillumination pupil response. Phosphene thresholds were significantly increased in patients with RP and correlated with the parameters of the pupil response if all subjects were considered. Within the RP group alone, this relationship was less pronounced and statistically not significant. Chromatic pupillography demonstrated a significant decrease in outer retinal photoreceptor responses but a persisting and disinhibited intrinsic photosensitive retinal ganglion cell function in advanced RP. These phenomena may be useful as an objective marker for the efficacy of any interventional treatment for hereditary retinal diseases as well as for the selection of suitable patients for an electronic retinal implant. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

A novel method for delivering ramped cooling reveals rat behaviours at innocuous and noxious temperatures: A comparative study of human psychophysics and rat behaviour.

PubMed

Dunham, James P; Hulse, Richard P; Donaldson, Lucy F

2015-07-15

Thermal sensory testing in rodents informs human pain research. There are important differences in the methodology for delivering thermal stimuli to humans and rodents. This is particularly true in cold pain research. These differences confound extrapolation and de-value nociceptive tests in rodents. We investigated cooling-induced behaviours in rats and psychophysical thresholds in humans using ramped cooling stimulation protocols. A Peltier device mounted upon force transducers simultaneously applied a ramped cooling stimulus whilst measuring contact with rat hind paw or human finger pad. Rat withdrawals and human detection, discomfort and pain thresholds were measured. Ramped cooling of a rat hind paw revealed two distinct responses: Brief paw removal followed by paw replacement, usually with more weight borne than prior to the removal (temperature inter-quartile range: 19.1 °C to 2.8 °C). Full withdrawal was evoked at colder temperatures (inter quartile range: -11.3 °C to -11.8 °C). The profile of human cool detection threshold and cold pain threshold were remarkably similar to that of the rat withdrawals behaviours. Previous rat cold evoked behaviours utilise static temperature stimuli. By utilising ramped cold stimuli this novel methodology better reflects thermal testing in patients. Brief paw removal in the rat is driven by non-nociceptive afferents, as is the perception of cooling in humans. This is in contrast to the nociceptor-driven withdrawal from colder temperatures. These findings have important implications for the interpretation of data generated in older cold pain models and consequently our understanding of cold perception and pain. Copyright © 2015. Published by Elsevier B.V.

Patient Perceptions of Breast Cancer Risk in Imaging-Detected Low-Risk Scenarios and Thresholds for Desired Intervention: A Multi-Institution Survey.

PubMed

Grimm, Lars J; Shelby, Rebecca A; Knippa, Emily E; Langman, Eun L; Miller, Lauren S; Whiteside, Beth E; Soo, Mary Scott C

2018-06-01

To determine women's perceptions of breast cancer risk and thresholds for desiring biopsy when considering BI-RADS 3 and 4A scenarios and recommendations, respectively. Women presenting for screening mammography from five geographically diverse medical centers were surveyed. Demographic information and baseline anxiety were queried. Participants were presented with scenarios of short-term imaging follow-up recommendations (ie, BI-RADS 3) and biopsy recommendations (ie, BI-RADS 4A) for low-risk mammographic abnormalities and asked to estimate their breast cancer risk for each scenario. Participants reported the threshold (ie, likelihood of cancer) where they would feel comfortable undergoing short-term imaging follow-up and biopsy and their anticipated regret for choosing short-term follow-up versus biopsy. Analysis of 2,747 surveys showed that participants estimated breast cancer risk of 32.8% for a BI-RADS 3 and 41.1% for a BI-RADS 4A scenarios are significantly greater rates than clinically established rates (<2% [P < .001] and 2%-10% [P < .001], respectively). Over one-half (55.4%) of participants reported they would never want imaging follow-up if there was any chance of cancer; two-thirds (66.2%) reported they would desire biopsy if there was any chance of cancer. Participants reported greater anticipated regret (P < .001) and less relief and confidence (P < .001) with the decision to undergo follow-up imaging versus biopsy. Women overestimate breast cancer risk associated with both BI-RADS 3 and 4A scenarios and desire very low biopsy thresholds. Greater anticipated regret and less relief and confidence was reported with the choice to undergo short-term imaging follow-up compared with biopsy. Copyright © 2018 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Perceptions of midline deviations among different facial types.

PubMed

Williams, Ryan P; Rinchuse, Daniel J; Zullo, Thomas G

2014-02-01

The correction of a deviated midline can involve complicated mechanics and a protracted treatment. The threshold below which midline deviations are considered acceptable might depend on multiple factors. The objective of this study was to evaluate the effect of facial type on laypersons' perceptions of various degrees of midline deviation. Smiling photographs of male and female subjects were altered to create 3 facial type variations (euryprosopic, mesoprosopic, and leptoprosopic) and deviations in the midline ranging from 0.0 to 4.0 mm. Evaluators rated the overall attractiveness and acceptability of each photograph. Data were collected from 160 raters. The overall threshold for the acceptability of a midline deviation was 2.92 ± 1.10 mm, with the threshold for the male subject significantly lower than that for the female subject. The euryprosopic facial type showed no decrease in mean attractiveness until the deviations were 2 mm or more. All other facial types were rated as decreasingly attractive from 1 mm onward. Among all facial types, the attractiveness of the male subject was only affected at deviations of 2 mm or greater; for the female subject, the attractiveness scores were significantly decreased at 1 mm. The mesoprosopic facial type was most attractive for the male subject but was the least attractive for the female subject. Facial type and sex may affect the thresholds at which a midline deviation is detected and above which a midline deviation is considered unacceptable. Both the euryprosopic facial type and male sex were associated with higher levels of attractiveness at relatively small levels of deviations. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Central Pain Processing in Early-Stage Parkinson's Disease: A Laser Pain fMRI Study

PubMed Central

Petschow, Christine; Scheef, Lukas; Paus, Sebastian; Zimmermann, Nadine; Schild, Hans H.; Klockgether, Thomas; Boecker, Henning

2016-01-01

Background & Objective Pain is a common non-motor symptom in Parkinson’s disease. As dopaminergic dysfunction is suggested to affect intrinsic nociceptive processing, this study was designed to characterize laser-induced pain processing in early-stage Parkinson’s disease patients in the dopaminergic OFF state, using a multimodal experimental approach at behavioral, autonomic, imaging levels. Methods 13 right-handed early-stage Parkinson’s disease patients without cognitive or sensory impairment were investigated OFF medication, along with 13 age-matched healthy control subjects. Measurements included warmth perception thresholds, heat pain thresholds, and central pain processing with event-related functional magnetic resonance imaging (erfMRI) during laser-induced pain stimulation at lower (E = 440 mJ) and higher (E = 640 mJ) target energies. Additionally, electrodermal activity was characterized during delivery of 60 randomized pain stimuli ranging from 440 mJ to 640 mJ, along with evaluation of subjective pain ratings on a visual analogue scale. Results No significant differences in warmth perception thresholds, heat pain thresholds, electrodermal activity and subjective pain ratings were found between Parkinson’s disease patients and controls, and erfMRI revealed a generally comparable activation pattern induced by laser-pain stimuli in brain areas belonging to the central pain matrix. However, relatively reduced deactivation was found in Parkinson’s disease patients in posterior regions of the default mode network, notably the precuneus and the posterior cingulate cortex. Conclusion Our data during pain processing extend previous findings suggesting default mode network dysfunction in Parkinson’s disease. On the other hand, they argue against a genuine pain-specific processing abnormality in early-stage Parkinson’s disease. Future studies are now required using similar multimodal experimental designs to examine pain processing in more advanced stages of Parkinson’s disease. PMID:27776130

High power single mode 980 nm AlGaInAs/AlGaAs quantum well lasers with a very low threshold current

NASA Astrophysics Data System (ADS)

Zhen, Dong; Cuiluan, Wang; Hongqi, Jing; Suping, Liu; Xiaoyu, Ma

2013-11-01

To achieve low threshold current as well as high single mode output power, a graded index separate confinement heterostructure (GRIN-SCH) AlGaInAs/AlGaAs quantum well laser with an optimized ridge waveguide was fabricated. The threshold current was reduced to 8 mA. An output power of 76 mW was achieved at 100 mA current at room temperature, with a slope efficiency of 0.83 W/A and a horizon divergent angle of 6.3°. The maximum single mode output power of the device reached as high as 450 mW.

Modulation of gut perception in humans by spatial summation phenomena

PubMed Central

Serra, Jordi; Azpiroz, Fernando; Malagelada, Juan-R

1998-01-01

We have recently shown that perception of intestinal stimuli increases by spatial summation phenomena. Our aim was to determine in humans whether intestinal perception depends on (a) the length of gut stimulated, and (b) the distance between stimuli. In a first series of studies, we compared perception of isobaric intestinal distensions applied over a 3 cm segment and a 36 cm segment by means of two separate barostats (n = 8). In a second series of studies we compared perception of intestinal distensions applied simultaneously by two balloons sited 3, 12 or 48 cm apart (n = 6). Distension of the 36 cm segment induced significantly greater perception than distension of the 3 cm intestinal segment (discomfort perceived at 20 ± 2 mmHg and 31 ± 2 mmHg, respectively; P < 0.05). Perception of intestinal balloon distension increased when a second stimulus was simultaneously applied, independently of the distance between the two balloons (the discomfort thresholds were 30 ± 11, 20 ± 6 and 28 ± 7% lower with simultaneous distensions 3, 12 and 48 cm apart, respectively). We conclude that perception of intestinal distension is determined by the extension of the field of stimulation, and the summation effect is similar whether adjacent or distant fields are stimulated. PMID:9490880

The Sensory Neurons of Touch

PubMed Central

Abraira, Victoria E.; Ginty, David D.

2013-01-01

The somatosensory system decodes a wide range of tactile stimuli and thus endows us with a remarkable capacity for object recognition, texture discrimination, sensory-motor feedback and social exchange. The first step leading to perception of innocuous touch is activation of cutaneous sensory neurons called low-threshold mechanoreceptors (LTMRs). Here, we review the properties and functions of LTMRs, emphasizing the unique tuning properties of LTMR subtypes and the organizational logic of their peripheral and central axonal projections. We discuss the spinal cord neurophysiological representation of complex mechanical forces acting upon the skin and current views of how tactile information is processed and conveyed from the spinal cord to the brain. An integrative model in which ensembles of impulses arising from physiologically distinct LTMRs are integrated and processed in somatotopically aligned mechanosensory columns of the spinal cord dorsal horn underlies the nervous system’s enormous capacity for perceiving the richness of the tactile world. PMID:23972592

The 1991 October 24 flare: A challenge for standard models

NASA Technical Reports Server (NTRS)

Beaujardiere, J.-F. De LA; Canfield, R. C.; Hudson, H. S.; Wulser, J.-P.; Acton, L.; Kosugi, T.; Masuda, S.

1995-01-01

The M9.8 solar flare of 1991 October 24 22:30 UT presents several interesting characteristics: (1) energy release starts high in the corona; (2) the primary chromospheric ribbons are initially well separated and do not move apart at an observable rate; (3) no evidence is found for an erupting filament or other driver. To explain this flare, we consider several canonical flare models, including a filament eruption, a confined filament eruption, current interruption, and interacting loops. We conclude that none of these scenarios unequivocally explains this flare. Two possibilities which cannot be ruled out are (1) the eruption of a filament unobservable in H-alpha which starts high in the corona and produces no ribbon motions smaller than our detection threshold and no perceptible expansion of the coronal X-ray source, and (2) energy release due to spontaneous, propagating reconnection which allows the system to essentially brighten in place.

Constant-current regulator improves tunnel diode threshold-detector performance

NASA Technical Reports Server (NTRS)

Cancro, C. A.

1965-01-01

Grounded-base transistor is placed in a tunnel diode threshold detector circuit, and a bias voltage is applied to the tunnel diode. This provides the threshold detector with maximum voltage output and overload protection.

What leads some people to think they are HIV-positive before knowing their diagnosis? A systematic review of psychological and behavioural correlates of HIV-risk perception.

PubMed

Evangeli, Michael; Baker, Laura L E; Pady, Kirsten; Jones, Bethanie; Wroe, Abigail L

2016-08-01

Current HIV-risk perception refers to the extent to which individuals think they might be HIV-positive. This belief, distinct from the perceived risk about being infected with HIV in the future, is likely to have a range of important consequences. These consequences may include both psychological effects (e.g., impacts on well-being) and behavioural effects (e.g., HIV testing uptake). Given these possible outcomes, and the suggested importance of risk perception in health behaviour models, understanding the behavioural and psychological antecedents of current HIV-risk perception is crucial. This systematic review investigates the relationship between behavioural and psychological factors and current HIV-risk perception (in individuals who are unaware of their actual HIV status). Eight studies were eligible for inclusion in the review (five quantitative and three qualitative studies). Drug risk behaviour and sexual risk behaviour (both self and partner) were often associated with current HIV-risk perception, although other studies failed to show a relationship between one's own sexual risk behaviour and risk perception. Psychological factors were only rarely assessed in relation to current HIV-risk perception. Where these variables were included, there was evidence that experiencing symptoms perceived to be consistent with HIV and prompts to test were associated with increased current HIV-risk perception. These findings are consistent with the Common-Sense Model (CSM) of illness representation and self-regulation. Methodological quality criteria were rarely met for the included studies. In addition, it was often difficult to ascertain whether potentially includable studies were eligible due to imprecise definitions of HIV-risk perception. Research and practice implications are discussed, with particular emphasis on the role of risk appraisals as a potential mediator of the relationship between HIV-risk behaviour, symptoms and current HIV-risk perception.

Neural signatures of conscious and unconscious emotional face processing in human infants.

PubMed

Jessen, Sarah; Grossmann, Tobias

2015-03-01

Human adults can process emotional information both with and without conscious awareness, and it has been suggested that the two processes rely on partly distinct brain mechanisms. However, the developmental origins of these brain processes are unknown. In the present event-related brain potential (ERP) study, we examined the brain responses of 7-month-old infants in response to subliminally (50 and 100 msec) and supraliminally (500 msec) presented happy and fearful facial expressions. Our results revealed that infants' brain responses (Pb and Nc) over central electrodes distinguished between emotions irrespective of stimulus duration, whereas the discrimination between emotions at occipital electrodes (N290 and P400) only occurred when faces were presented supraliminally (above threshold). This suggests that early in development the human brain not only discriminates between happy and fearful facial expressions irrespective of conscious perception, but also that, similar to adults, supraliminal and subliminal emotion processing relies on distinct neural processes. Our data further suggest that the processing of emotional facial expressions differs across infants depending on their behaviorally shown perceptual sensitivity. The current ERP findings suggest that distinct brain processes underpinning conscious and unconscious emotion perception emerge early in ontogeny and can therefore be seen as a key feature of human social functioning. Copyright © 2014 Elsevier Ltd. All rights reserved.

Transformation-aware perceptual image metric

NASA Astrophysics Data System (ADS)

Kellnhofer, Petr; Ritschel, Tobias; Myszkowski, Karol; Seidel, Hans-Peter

2016-09-01

Predicting human visual perception has several applications such as compression, rendering, editing, and retargeting. Current approaches, however, ignore the fact that the human visual system compensates for geometric transformations, e.g., we see that an image and a rotated copy are identical. Instead, they will report a large, false-positive difference. At the same time, if the transformations become too strong or too spatially incoherent, comparing two images gets increasingly difficult. Between these two extrema, we propose a system to quantify the effect of transformations, not only on the perception of image differences but also on saliency and motion parallax. To this end, we first fit local homographies to a given optical flow field, and then convert this field into a field of elementary transformations, such as translation, rotation, scaling, and perspective. We conduct a perceptual experiment quantifying the increase of difficulty when compensating for elementary transformations. Transformation entropy is proposed as a measure of complexity in a flow field. This representation is then used for applications, such as comparison of nonaligned images, where transformations cause threshold elevation, detection of salient transformations, and a model of perceived motion parallax. Applications of our approach are a perceptual level-of-detail for real-time rendering and viewpoint selection based on perceived motion parallax.

The effects of tones in noise on human annoyance and performance

NASA Astrophysics Data System (ADS)

Lee, Joonhee

Building mechanical equipment often generates prominent tones because most systems include rotating parts like fans and pumps. These tonal noises can cause unpleasant user experiences in spaces and, in turn, lead to increased complaints by building occupants. Currently, architectural engineers can apply the noise criteria guidelines in standards or publications to achieve acceptable noise conditions for assorted types of spaces. However, these criteria do not apply well if the noise contains perceptible tones. The annoyance thresholds experienced by the general population with regards to the degree of tones in noise is a significant piece of knowledge that has not been well-established. Thus, this dissertation addresses the relationship between human perception and noises with tones in the built environment. Four phases of subjective testing were conducted in an indoor acoustic testing chamber at the University of Nebraska to achieve the research objective. The results indicate that even the least prominent tones in noises can significantly decrease the cognitive performance of participants on a mentally demanding task. Factorial repeated-measures analysis of variance of test results have proven that tonality has a crucial influence on working memory capacity of subjects, whereas loudness levels alone did not. A multidimensional annoyance model, incorporating psycho-acoustical attributes of noise in addition to loudness and tonality, has been proposed as a more accurate annoyance model.

Amplitude modulation detection with concurrent frequency modulation.

PubMed

Nagaraj, Naveen K

2016-09-01

Human speech consists of concomitant temporal modulations in amplitude and frequency that are crucial for speech perception. In this study, amplitude modulation (AM) detection thresholds were measured for 550 and 5000 Hz carriers with and without concurrent frequency modulation (FM), at AM rates crucial for speech perception. Results indicate that adding 40 Hz FM interferes with AM detection, more so for 5000 Hz carrier and for frequency deviations exceeding the critical bandwidth of the carrier frequency. These findings suggest that future cochlear implant processors, encoding speech fine-structures may consider limiting the FM to narrow bandwidth and to low frequencies.

Income (In-) Adequacy? The Official Poverty Line, Possible Changes, and Some Historical Lessons.

ERIC Educational Resources Information Center

Fisher, Gordon

1999-01-01

Examines the current official poverty thresholds (including Orshansky's thresholds) and the possibility that a new poverty measure may be adopted soon, discussing the thresholds from a historical perspective. Lessons drawn from the history of poverty thresholds and of early unofficial poverty lines in the United States are included. Recent…

Hearing disability and communication handicap for compensation purposes based on self-assessment and audiometric testing.

PubMed

Salomon, G; Parving, A

1985-01-01

It is reasoned that for compensation or epidemiological studies an evaluation of hearing disability and the concomitant handicap must include the ability to perceive visual cues. A scaling procedure for hearing- and audiovisual communication handicap is presented. The procedure deviates in two ways from previous handicap assessments: (1) It is based on individual self-assessment of semantic speech perception but can be implemented by means of professional audiological test procedures. (2) The system does not make use of pure-tone auditory thresholds as a predominant audiological principle, but is based on speech perception. The interrelationship between auditory and audiovisual handicap is evaluated. A total score including audio- and audiovisual perception handicap is proposed and a suggestion for disability percentages is presented.

Transverse tripolar stimulation of peripheral nerve: a modelling study of spatial selectivity.

PubMed

Deurloo, K E; Holsheimer, J; Boom, H B

1998-01-01

Various anode-cathode configurations in a nerve cuff are modelled to predict their spatial selectivity characteristics for functional nerve stimulation. A 3D volume conductor model of a monofascicular nerve is used for the computation of stimulation-induced field potentials, whereas a cable model of myelinated nerve fibre is used for the calculation of the excitation thresholds of fibres. As well as the usual configurations (monopole, bipole, longitudinal tripole, 'steering' anode), a transverse tripolar configuration (central cathode) is examined. It is found that the transverse tripole is the only configuration giving convex recruitment contours and therefore maximises activation selectivity for a small (cylindrical) bundle of fibres in the periphery of a monofascicular nerve trunk. As the electrode configuration is changed to achieve greater selectivity, the threshold current increases. Therefore threshold currents for fibre excitation with a transverse tripole are relatively high. Inverse recruitment is less extreme than for the other configurations. The influences of several geometrical parameters and model conductivities of the transverse tripole on selectivity and threshold current are analysed. In chronic implantation, when electrodes are encapsulated by a layer of fibrous tissue, threshold currents are low, whereas the shape of the recruitment contours in transverse tripolar stimulation does not change.

Children's weighting strategies for word-final stop voicing are not explained by auditory sensitivities.

PubMed

Nittrouer, Susan; Lowenstein, Joanna H

2007-02-01

It has been reported that children and adults weight differently the various acoustic properties of the speech signal that support phonetic decisions. This finding is generally attributed to the fact that the amount of weight assigned to various acoustic properties by adults varies across languages, and that children have not yet discovered the mature weighting strategies of their own native languages. But an alternative explanation exists: Perhaps children's auditory sensitivities for some acoustic properties of speech are poorer than those of adults, and children cannot categorize stimuli based on properties to which they are not keenly sensitive. The purpose of the current study was to test that hypothesis. Edited-natural, synthetic-formant, and sine wave stimuli were all used, and all were modeled after words with voiced and voiceless final stops. Adults and children (5 and 7 years of age) listened to pairs of stimuli in 5 conditions: 2 involving a temporal property (1 with speech and 1 with nonspeech stimuli) and 3 involving a spectral property (1 with speech and 2 with nonspeech stimuli). An AX discrimination task was used in which a standard stimulus (A) was compared with all other stimuli (X) equal numbers of times (method of constant stimuli). Adults and children had similar difference thresholds (i.e., 50% point on the discrimination function) for 2 of the 3 sets of nonspeech stimuli (1 temporal and 1 spectral), but children's thresholds were greater for both sets of speech stimuli. Results are interpreted as evidence that children's auditory sensitivities are adequate to support weighting strategies similar to those of adults, and so observed differences between children and adults in speech perception cannot be explained by differences in auditory perception. Furthermore, it is concluded that listeners bring expectations to the listening task about the nature of the signals they are hearing based on their experiences with those signals.

Low-threshold high-T/0/ constricted double heterojunction AlGaAs diode lasers

NASA Technical Reports Server (NTRS)

Botez, D.; Connolly, J. C.

1980-01-01

Constricted double heterojunction diode lasers of relatively low CW thresholds (28-40 mA) are obtained by growing structures that maximize the amount of current flow into the lasing spot. These values are obtained while still using standard 10 microns wide oxide-defined stripe contacts. Over the 20-70 C temperature interval, threshold current temperature coefficients as high as 320 C and a virtually constant external differential quantum efficiency, are found.

Unconscious Inhibition and Facilitation at the Objective Detection Threshold: Replicable and Qualitatively Different Unconscious Perceptual Effects

ERIC Educational Resources Information Center

Snodgrass, Michael; Shevrin, Howard

2006-01-01

Although the veridicality of unconscious perception is increasingly accepted, core issues remain unresolved [Jack, A., & Shallice, T. (2001). Introspective physicalism as an approach to the science of consciousness. "Cognition, 79," 161-196], and sharp disagreement persists regarding fundamental methodological and theoretical issues. The most…

Binary ROCs in Perception and Recognition Memory Are Curved

ERIC Educational Resources Information Center

Dube, Chad; Rotello, Caren M.

2012-01-01

In recognition memory, a classic finding is that receiver operating characteristics (ROCs) are curvilinear. This has been taken to support the fundamental assumptions of signal detection theory (SDT) over discrete-state models such as the double high-threshold model (2HTM), which predicts linear ROCs. Recently, however, Broder and Schutz (2009)…

Combined Atropine and 2-PAM Cl Effects on Tracking Performance and Visual, Physiological, and Psychological Functions

DTIC Science & Technology

1988-12-01

tracking task reveals the magnitude Akitrihm. Spare. and Environmental Medicine • December. I$ II I ANTIDOTE EFFECTS--PEN ETAR ET AL. and duration of the... marihuana on dynamic visual acu- blood pressure following the combination of 2-PAM Cl ity: I. Threshold measurements. Perception Psychophys. 1975

Pilot Studies on Object Motion Perception During Linear Self-Motion After Long Duration Centrifugation of Human Subjects

DTIC Science & Technology

1993-02-01

Taylor & Creelman , 1967.) Measurements were taken with the sled moving either in forward or backward direction, each threshold being measured once...Furrer, R. & Messerschmid, E. (1990). Space Sickness on Earth. Experimental Brain Research 79(3), 661-663. Taylor, M.M. & Creelman . C.D. (1967). PEST

An Evaluation of Psychophysical Models of Auditory Change Perception

ERIC Educational Resources Information Center

Micheyl, Christophe; Kaernbach, Christian; Demany, Laurent

2008-01-01

In many psychophysical experiments, the participant's task is to detect small changes along a given stimulus dimension or to identify the direction (e.g., upward vs. downward) of such changes. The results of these experiments are traditionally analyzed with a constant-variance Gaussian (CVG) model or a high-threshold (HT) model. Here, the authors…

The Limits of Human Stereopsis in Space and Time

PubMed Central

Kane, David; Guan, Phillip

2014-01-01

To encode binocular disparity, the visual system determines the image patches in one eye that yield the highest correlation with patches in the other eye. The computation of interocular correlation occurs after spatiotemporal filtering of monocular signals, which leads to restrictions on disparity variations that can support depth perception. We quantified those restrictions by measuring humans' ability to see disparity variation at a wide range of spatial and temporal frequencies. Lower-disparity thresholds cut off at very low spatiotemporal frequencies, which is consistent with the behavior of V1 neurons. Those thresholds are space–time separable, suggesting that the underlying neural mechanisms are separable. We also found that upper-disparity limits were characterized by a spatiotemporal, disparity-gradient limit; to be visible, disparity variation cannot exceed a fixed amount for a given interval in space–time. Our results illustrate that the disparity variations that humans can see are very restricted compared with the corresponding luminance variations. The results also provide insight into the neural mechanisms underlying depth from disparity, such as why stimuli with long interocular delays can still yield clear depth percepts. PMID:24453329

Effect of gap detection threshold on consistency of speech in children with speech sound disorder.

PubMed

Sayyahi, Fateme; Soleymani, Zahra; Akbari, Mohammad; Bijankhan, Mahmood; Dolatshahi, Behrooz

2017-02-01

The present study examined the relationship between gap detection threshold and speech error consistency in children with speech sound disorder. The participants were children five to six years of age who were categorized into three groups of typical speech, consistent speech disorder (CSD) and inconsistent speech disorder (ISD).The phonetic gap detection threshold test was used for this study, which is a valid test comprised six syllables with inter-stimulus intervals between 20-300ms. The participants were asked to listen to the recorded stimuli three times and indicate whether they heard one or two sounds. There was no significant difference between the typical and CSD groups (p=0.55), but there were significant differences in performance between the ISD and CSD groups and the ISD and typical groups (p=0.00). The ISD group discriminated between speech sounds at a higher threshold. Children with inconsistent speech errors could not distinguish speech sounds during time-limited phonetic discrimination. It is suggested that inconsistency in speech is a representation of inconsistency in auditory perception, which causes by high gap detection threshold. Copyright © 2016 Elsevier Ltd. All rights reserved.

A window on perception: Response times of odontocete cetaceans in audiometric tests

NASA Astrophysics Data System (ADS)

Blackwood, Diane J.; Ridgway, Sam H.; Evans, William E.

2002-05-01

A standard psychometric measurement is response time, the interval elapsing between a stimulus and a response. While studies of response time have been published for humans and other terrestrial mammals, this study marks the first report of response times for odontocete cetaceans at threshold in an audiometric task. Two white whales (Delphinapterus leucas) and four Atlantic bottlenose dolphins (Tursiops truncatus) were given audiometric tests to determine masked hearing thresholds. Animals were tested at 26 frequencies over a range from 200 Hz to 100 kHz using pure tones. The test tone amplitudes covered a range of 20 dB re 1 microPascal including the hearing threshold of the animal at that frequency. Hearing thresholds varied from 87.5 dB to 125.5 dB depending on frequency, masking noise intensity and individual animal. Data was analyzed to determine characteristic relationships between response time and amplitude of test tone for each frequency and animal. The two whales responded significantly slower (640 ms, 0.001) than the four dolphins (430 ms). As in terrestrial animals, reaction time became shorter as stimulus strength increased. At threshold, median response time across frequencies within each animal varied about 150 ms.

More superimposition for contrast-modulated than luminance-modulated stimuli during binocular rivalry.

PubMed

Skerswetat, Jan; Formankiewicz, Monika A; Waugh, Sarah J

2018-01-01

Luminance-modulated noise (LM) and contrast-modulated noise (CM) gratings were presented with interocularly correlated, uncorrelated and anti-correlated binary noise to investigate their contributions to mixed percepts, specifically piecemeal and superimposition, during binocular rivalry. Stimuli were sine-wave gratings of 2 c/deg presented within 2 deg circular apertures. The LM stimulus contrast was 0.1 and the CM stimulus modulation depth was 1.0, equating to approximately 5 and 7 times detection threshold, respectively. Twelve 45 s trials, per noise configuration, were carried out. Fifteen participants with normal vision indicated via button presses whether an exclusive, piecemeal or superimposed percept was seen. For all noise conditions LM stimuli generated more exclusive visibility, and lower proportions of superimposition. CM stimuli led to greater proportions and longer periods of superimposition. For both stimulus types, correlated interocular noise generated more superimposition than did anti- or uncorrelated interocular noise. No significant effect of stimulus type (LM vs CM) or noise configuration (correlated, uncorrelated, anti-correlated) on piecemeal perception was found. Exclusive visibility was greater in proportion, and perceptual changes more numerous, during binocular rivalry for CM stimuli when interocular noise was not correlated. This suggests that mutual inhibition, initiated by non-correlated noise CM gratings, occurs between neurons processing luminance noise (first-order component), as well as those processing gratings (second-order component). Therefore, first- and second-order components can contribute to overall binocular rivalry responses. We suggest the addition of a new well to the current energy landscape model for binocular rivalry that takes superimposition into account. Copyright © 2017 Elsevier Ltd. All rights reserved.

Contrast discrimination: Second responses reveal the relationship between the mean and variance of visual signals

PubMed Central

Solomon, Joshua A.

2007-01-01

To explain the relationship between first- and second-response accuracies in a detection experiment, Swets, Tanner, and Birdsall [Swets, J., Tanner, W. P., Jr., & Birdsall, T. G. (1961). Decision processes in perception. Psychological Review, 68, 301–340] proposed that the variance of visual signals increased with their means. However, both a low threshold and intrinsic uncertainty produce similar relationships. I measured the relationship between first- and second-response accuracies for suprathreshold contrast discrimination, which is thought to be unaffected by sensory thresholds and intrinsic uncertainty. The results are consistent with a slowly increasing variance. PMID:17961625

Individual and organizational predictors of depression in general practitioners.

PubMed

Firth-Cozens, J

1998-10-01

High levels of stress and depression are seen in both general practitioners (GPs) and hospital doctors, and this has implications for patient care. It is therefore important to discover the individual and organizational causes of elevated symptoms so they can be tackled. To discover the relative importance of individual characteristics measured 10 years earlier compared with current organizational stressors in predicting depression in GPs. Longitudinal questionnaire study, using data from those of the original cohort of 318 medical students who are now GPs (n = 131), considering perceptions of current stressors and comparing through regression analyses the relative strength of early personality and mood with current organizational factors of sleep, hours worked, and practice size in predicting current depression levels. There were 22 (17%) stressors scoring above threshold for depression. Relationships with senior doctors and patients are the main reported stressors, followed by making mistakes and conflict of career with personal life. The predictors of symptom levels varied for men and women. In men, depression and self-criticism as students, and current sleep levels; and in women, sibling rivalry and current alcohol use, were the main predictors: in men, 27% of the variance was accounted for by early dispositional factors alone compared with 14% in women. A model is suggested linking sleep loss with workplace stressors, self-critical cognitions, and depression. Interventions can be made throughout training, targeting self-criticism and recognizing early depression, while later addressing the organizational stressors, particularly work relationships and sleep patterns.

SONOS Nonvolatile Memory Cell Programming Characteristics

NASA Technical Reports Server (NTRS)

MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

2010-01-01

Silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile memory is gaining favor over conventional EEPROM FLASH memory technology. This paper characterizes the SONOS write operation using a nonquasi-static MOSFET model. This includes floating gate charge and voltage characteristics as well as tunneling current, voltage threshold and drain current characterization. The characterization of the SONOS memory cell predicted by the model closely agrees with experimental data obtained from actual SONOS memory cells. The tunnel current, drain current, threshold voltage and read drain current all closely agreed with empirical data.

Effects of chemotherapy on gene expression of lingual taste receptors in patients with head and neck cancer.

PubMed

Tsutsumi, Rie; Goda, Masakazu; Fujimoto, Chisa; Kanno, Kyoko; Nobe, Misaki; Kitamura, Yoshiaki; Abe, Koji; Kawai, Misako; Matsumoto, Hideki; Sakai, Tohru; Takeda, Noriaki

2016-03-01

We aimed to test the hypothesis that chemotherapy changes the gene expression of taste receptors in the tongue to induce dysgeusia in patients with head and neck cancer. Prospective observation study. We enrolled 21 patients who received chemoradiotherapy and five patients who underwent radiotherapy for head and neck cancer. The messenger RNA (mRNA) levels of the taste receptor subunits T1R1, T1R2, T1R3, and T2R5 were measured in lingual mucosa scrapings obtained with a small spatula. The perception thresholds of umami, sweet, and bitter tastes were assessed by the whole mouth gustatory test. In four patients with severe stomatitis induced by chemoradiotherapy, the mRNA levels of T1R1, T1R2, T1R3, and T2R5 in the lingual mucosa were significantly decreased. However, in 17 patients with mild/moderate stomatitis, the mRNA levels of T1R3 were significantly and transiently decreased, whereas those of T1R1 and T1R2 remained unchanged and those of T2R5 mRNA were significantly and transiently increased after chemotherapy. There was a significant negative correlation between the perception thresholds of umami or sweet tastes and lingual mRNA levels of T1R3 in patients with mild/moderate stomatitis after chemotherapy. Although the perception threshold of bitter taste remained unchanged, lingual mRNA levels of T2R5 were significantly increased in patients who complained of phantogeusia after chemotherapy. Chemotherapy specifically changed the gene expression of T1R3 and T2R5 in head and neck cancer patients with mild/moderate stomatitis, resulting in both dysgeusia of umami and sweet tastes as well as phantogeusia. 4. Laryngoscope, 126:E103-E109, 2016. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

Enhanced perception of pitch changes in speech and music in early blind adults.

PubMed

Arnaud, Laureline; Gracco, Vincent; Ménard, Lucie

2018-06-12

It is well known that congenitally blind adults have enhanced auditory processing for some tasks. For instance, they show supra-normal capacity to perceive accelerated speech. However, only a few studies have investigated basic auditory processing in this population. In this study, we investigated if pitch processing enhancement in the blind is a domain-general or domain-specific phenomenon, and if pitch processing shares the same properties as in the sighted regarding how scores from different domains are associated. Fifteen congenitally blind adults and fifteen sighted adults participated in the study. We first created a set of personalized native and non-native vowel stimuli using an identification and rating task. Then, an adaptive discrimination paradigm was used to determine the frequency difference limen for pitch direction identification of speech (native and non-native vowels) and non-speech stimuli (musical instruments and pure tones). The results show that the blind participants had better discrimination thresholds than controls for native vowels, music stimuli, and pure tones. Whereas within the blind group, the discrimination thresholds were smaller for musical stimuli than speech stimuli, replicating previous findings in sighted participants, we did not find this effect in the current control group. Further analyses indicate that older sighted participants show higher thresholds for instrument sounds compared to speech sounds. This effect of age was not found in the blind group. Moreover, the scores across domains were not associated to the same extent in the blind as they were in the sighted. In conclusion, in addition to providing further evidence of compensatory auditory mechanisms in early blind individuals, our results point to differences in how auditory processing is modulated in this population. Copyright © 2018 Elsevier Ltd. All rights reserved.

Definition of temperature thresholds: the example of the French heat wave warning system.

PubMed

Pascal, Mathilde; Wagner, Vérène; Le Tertre, Alain; Laaidi, Karine; Honoré, Cyrille; Bénichou, Françoise; Beaudeau, Pascal

2013-01-01

Heat-related deaths should be somewhat preventable. In France, some prevention measures are activated when minimum and maximum temperatures averaged over three days reach city-specific thresholds. The current thresholds were computed based on a descriptive analysis of past heat waves and on local expert judgement. We tested whether a different method would confirm these thresholds. The study was set in the six cities of Paris, Lyon, Marseille, Nantes, Strasbourg and Limoges between 1973 and 2003. For each city, we estimated the excess in mortality associated with different temperature thresholds, using a generalised additive model, controlling for long-time trends, seasons and days of the week. These models were used to compute the mortality predicted by different percentiles of temperatures. The thresholds were chosen as the percentiles associated with a significant excess mortality. In all cities, there was a good correlation between current thresholds and the thresholds derived from the models, with 0°C to 3°C differences for averaged maximum temperatures. Both set of thresholds were able to anticipate the main periods of excess mortality during the summers of 1973 to 2003. A simple method relying on descriptive analysis and expert judgement is sufficient to define protective temperature thresholds and to prevent heat wave mortality. As temperatures are increasing along with the climate change and adaptation is ongoing, more research is required to understand if and when thresholds should be modified.

Implications of Minimizing Trauma During Conventional Cochlear Implantation

PubMed Central

Carlson, Matthew L.; Driscoll, Colin L. W.; Gifford, René H.; Service, Geoffrey J.; Tombers, Nicole M.; Hughes-Borst, Becky J.; Neff, Brian A.; Beatty, Charles W.

2014-01-01

Objective To describe the relationship between implantation-associated trauma and postoperative speech perception scores among adult and pediatric patients undergoing cochlear implantation using conventional length electrodes and minimally traumatic surgical techniques. Study Design Retrospective chart review (2002–2010). Setting Tertiary academic referral center. Patients All subjects with significant preoperative low-frequency hearing (≤70 dB HL at 250 Hz) who underwent cochlear implantation with a newer generation implant electrode (Nucleus Contour Advance, Advanced Bionics HR90K [1J and Helix], and Med El Sonata standard H array) were reviewed. Intervention(s) Preimplant and postimplant audiometric thresholds and speech recognition scores were recorded using the electronic medical record. Main Outcome Measure(s) Postimplantation pure tone threshold shifts were used as a surrogate measure for extent of intracochlear injury and correlated with postoperative speech perception scores. Results Between 2002 and 2010, 703 cochlear implant (CI) operations were performed. Data from 126 implants were included in the analysis. The mean preoperative low-frequency pure-tone average was 55.4 dB HL. Hearing preservation was observed in 55% of patients. Patients with hearing preservation were found to have significantly higher postoperative speech perception performance in the cochlear implantation-only condition than those who lost all residual hearing. Conclusion Conservation of acoustic hearing after conventional length cochlear implantation is unpredictable but remains a realistic goal. The combination of improved technology and refined surgical technique may allow for conservation of some residual hearing in more than 50% of patients. Germane to the conventional length CI recipient with substantial hearing loss, minimizing trauma allows for improved speech perception in the electric condition. These findings support the use of minimally traumatic techniques in all CI recipients, even those destined for electric-only stimulation. PMID:21659922

Effects of Noise Level and Cognitive Function on Speech Perception in Normal Elderly and Elderly with Amnestic Mild Cognitive Impairment.

PubMed

Lee, Soo Jung; Park, Kyung Won; Kim, Lee-Suk; Kim, HyangHee

2016-06-01

Along with auditory function, cognitive function contributes to speech perception in the presence of background noise. Older adults with cognitive impairment might, therefore, have more difficulty perceiving speech-in-noise than their peers who have normal cognitive function. We compared the effects of noise level and cognitive function on speech perception in patients with amnestic mild cognitive impairment (aMCI), cognitively normal older adults, and cognitively normal younger adults. We studied 14 patients with aMCI and 14 age-, education-, and hearing threshold-matched cognitively intact older adults as experimental groups, and 14 younger adults as a control group. We assessed speech perception with monosyllabic word and sentence recognition tests at four noise levels: quiet condition and signal-to-noise ratio +5 dB, 0 dB, and -5 dB. We also evaluated the aMCI group with a neuropsychological assessment. Controlling for hearing thresholds, we found that the aMCI group scored significantly lower than both the older adults and the younger adults only when the noise level was high (signal-to-noise ratio -5 dB). At signal-to-noise ratio -5 dB, both older groups had significantly lower scores than the younger adults on the sentence recognition test. The aMCI group's sentence recognition performance was related to their executive function scores. Our findings suggest that patients with aMCI have more problems communicating in noisy situations in daily life than do their cognitively healthy peers and that older listeners with more difficulties understanding speech in noise should be considered for testing of neuropsychological function as well as hearing.

New perspectives on taste and primate evolution: the dichotomy in gustatory coding for perception of beneficent versus noxious substances as supported by correlations among human thresholds.

PubMed

Hladik, Claude-Marcel; Pasquet, P; Simmen, B

2002-04-01

In various environments where primates are presently observed, as well as in forests and savannas which have been inhabited by australopithecines and early hominids, there are (or there have been presumably) categories of substances eliciting taste signals associated with stereotyped responses. Such is the case for various soluble sugars of fruits and nectars, attracting consumers, and for several plant compounds in which bitter or strongly astringent properties have a repulsive effect. The occurrence of such classes of tasty substances among natural products appears to be related to the evolutionary trends that shaped primate sensory perception (for detecting either beneficent or potentially noxious substances) in the context of a long history of coevolution between animals and plants. Here, we present original psychophysical data on humans (412 individuals aged 17-59 years) as an analogy with which to test recent evidence from electrophysiology in nonhuman primates (Hellekant et al. [1997] J. Neurophysiol. 77:978-993; Danilova et al. [1998] Ann. N.Y. Acad. Sci. 855:160-164) that taste fibers can be grouped into clusters of "best-responding fibers" with two more specific clusters, one for sugars and one for quinine and tannins. The collinearity found between human taste responses (recognition thresholds) for fructose and sucrose, as well as for quinine and tannins, is presented and discussed as another evidence of the two-direction evolutionary trend determining taste sensitivity. Salt perception appears to be totally independent of these trends. Accordingly, the appreciation of a salty taste seems to be a recent culturally learned response, and not a primary taste perception. The very existence of primary tastes is discussed in the context of evolutionary trends, past and present. Copyright 2002 Wiley-Liss, Inc.

Cortical activation patterns correlate with speech understanding after cochlear implantation

PubMed Central

Olds, Cristen; Pollonini, Luca; Abaya, Homer; Larky, Jannine; Loy, Megan; Bortfeld, Heather; Beauchamp, Michael S.; Oghalai, John S.

2015-01-01

Objectives Cochlear implants are a standard therapy for deafness, yet the ability of implanted patients to understand speech varies widely. To better understand this variability in outcomes, we used functional near-infrared spectroscopy (fNIRS) to image activity within regions of the auditory cortex and compare the results to behavioral measures of speech perception. Design We studied 32 deaf adults hearing through cochlear implants and 35 normal-hearing controls. We used fNIRS to measure responses within the lateral temporal lobe and the superior temporal gyrus to speech stimuli of varying intelligibility. The speech stimuli included normal speech, channelized speech (vocoded into 20 frequency bands), and scrambled speech (the 20 frequency bands were shuffled in random order). We also used environmental sounds as a control stimulus. Behavioral measures consisted of the Speech Reception Threshold, CNC words, and AzBio Sentence tests measured in quiet. Results Both control and implanted participants with good speech perception exhibited greater cortical activations to natural speech than to unintelligible speech. In contrast, implanted participants with poor speech perception had large, indistinguishable cortical activations to all stimuli. The ratio of cortical activation to normal speech to that of scrambled speech directly correlated with the CNC Words and AzBio Sentences scores. This pattern of cortical activation was not correlated with auditory threshold, age, side of implantation, or time after implantation. Turning off the implant reduced cortical activations in all implanted participants. Conclusions Together, these data indicate that the responses we measured within the lateral temporal lobe and the superior temporal gyrus correlate with behavioral measures of speech perception, demonstrating a neural basis for the variability in speech understanding outcomes after cochlear implantation. PMID:26709749

Wind speed perception and risk.

PubMed

Agdas, Duzgun; Webster, Gregory D; Masters, Forrest J

2012-01-01

How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

Device for monitoring cell voltage

DOEpatents

Doepke, Matthias [Garbsen, DE; Eisermann, Henning [Edermissen, DE

2012-08-21

A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

Prefrontal cortex modulates posterior alpha oscillations during top-down guided visual perception

PubMed Central

Helfrich, Randolph F.; Huang, Melody; Wilson, Guy; Knight, Robert T.

2017-01-01

Conscious visual perception is proposed to arise from the selective synchronization of functionally specialized but widely distributed cortical areas. It has been suggested that different frequency bands index distinct canonical computations. Here, we probed visual perception on a fine-grained temporal scale to study the oscillatory dynamics supporting prefrontal-dependent sensory processing. We tested whether a predictive context that was embedded in a rapid visual stream modulated the perception of a subsequent near-threshold target. The rapid stream was presented either rhythmically at 10 Hz, to entrain parietooccipital alpha oscillations, or arrhythmically. We identified a 2- to 4-Hz delta signature that modulated posterior alpha activity and behavior during predictive trials. Importantly, delta-mediated top-down control diminished the behavioral effects of bottom-up alpha entrainment. Simultaneous source-reconstructed EEG and cross-frequency directionality analyses revealed that this delta activity originated from prefrontal areas and modulated posterior alpha power. Taken together, this study presents converging behavioral and electrophysiological evidence for frontal delta-mediated top-down control of posterior alpha activity, selectively facilitating visual perception. PMID:28808023

The perception of microsound and its musical implications.

PubMed

Roads, Curtis

2003-11-01

Sound particles or microsounds last only a few milliseconds, near the threshold of auditory perception. We can easily analyze the physical properties of sound particles either individually or in masses. However, correlating these properties with human perception remains complicated. One cannot speak of a single time frame, or a "time constant" for the auditory system. The hearing mechanism involves many different agents, each of which operates on its own timescale. The signals being sent by diverse hearing agents are integrated by the brain into a coherent auditory picture. The pioneer of "sound quanta," Dennis Gabor (1900-1979), suggested that at least two mechanisms are at work in microevent detection: one that isolates events, and another that ascertains their pitch. Human hearing imposes a certain minimum duration in order to establish a firm sense of pitch, amplitude, and timbre. This paper traces disparate strands of literature on the topic and summarizes their meaning. Specifically, we examine the perception of intensity and pitch of microsounds, the phenomena of tone fusion and fission, temporal auditory acuity, and preattentive perception. The final section examines the musical implications of microsonic analysis, synthesis, and transformation.

Cochlear implantation with hearing preservation yields significant benefit for speech recognition in complex listening environments

PubMed Central

Gifford, René H.; Dorman, Michael F.; Skarzynski, Henryk; Lorens, Artur; Polak, Marek; Driscoll, Colin L. W.; Roland, Peter; Buchman, Craig A.

2012-01-01

Objective The aim of this study was to assess the benefit of having preserved acoustic hearing in the implanted ear for speech recognition in complex listening environments. Design The current study included a within subjects, repeated-measures design including 21 English speaking and 17 Polish speaking cochlear implant recipients with preserved acoustic hearing in the implanted ear. The patients were implanted with electrodes that varied in insertion depth from 10 to 31 mm. Mean preoperative low-frequency thresholds (average of 125, 250 and 500 Hz) in the implanted ear were 39.3 and 23.4 dB HL for the English- and Polish-speaking participants, respectively. In one condition, speech perception was assessed in an 8-loudspeaker environment in which the speech signals were presented from one loudspeaker and restaurant noise was presented from all loudspeakers. In another condition, the signals were presented in a simulation of a reverberant environment with a reverberation time of 0.6 sec. The response measures included speech reception thresholds (SRTs) and percent correct sentence understanding for two test conditions: cochlear implant (CI) plus low-frequency hearing in the contralateral ear (bimodal condition) and CI plus low-frequency hearing in both ears (best aided condition). A subset of 6 English-speaking listeners were also assessed on measures of interaural time difference (ITD) thresholds for a 250-Hz signal. Results Small, but significant, improvements in performance (1.7 – 2.1 dB and 6 – 10 percentage points) were found for the best-aided condition vs. the bimodal condition. Postoperative thresholds in the implanted ear were correlated with the degree of EAS benefit for speech recognition in diffuse noise. There was no reliable relationship among measures of audiometric threshold in the implanted ear nor elevation in threshold following surgery and improvement in speech understanding in reverberation. There was a significant correlation between ITD threshold at 250 Hz and EAS-related benefit for the adaptive SRT. Conclusions Our results suggest that (i) preserved low-frequency hearing improves speech understanding for CI recipients (ii) testing in complex listening environments, in which binaural timing cues differ for signal and noise, may best demonstrate the value of having two ears with low-frequency acoustic hearing and (iii) preservation of binaural timing cues, albeit poorer than observed for individuals with normal hearing, is possible following unilateral cochlear implantation with hearing preservation and is associated with EAS benefit. Our results demonstrate significant communicative benefit for hearing preservation in the implanted ear and provide support for the expansion of cochlear implant criteria to include individuals with low-frequency thresholds in even the normal to near-normal range. PMID:23446225

Value of information and pricing new healthcare interventions.

PubMed

Willan, Andrew R; Eckermann, Simon

2012-06-01

Previous application of value-of-information methods to optimal clinical trial design have predominantly taken a societal decision-making perspective, implicitly assuming that healthcare costs are covered through public expenditure and trial research is funded by government or donation-based philanthropic agencies. In this paper, we consider the interaction between interrelated perspectives of a societal decision maker (e.g. the National Institute for Health and Clinical Excellence [NICE] in the UK) charged with the responsibility for approving new health interventions for reimbursement and the company that holds the patent for a new intervention. We establish optimal decision making from societal and company perspectives, allowing for trade-offs between the value and cost of research and the price of the new intervention. Given the current level of evidence, there exists a maximum (threshold) price acceptable to the decision maker. Submission for approval with prices above this threshold will be refused. Given the current level of evidence and the decision maker's threshold price, there exists a minimum (threshold) price acceptable to the company. If the decision maker's threshold price exceeds the company's, then current evidence is sufficient since any price between the thresholds is acceptable to both. On the other hand, if the decision maker's threshold price is lower than the company's, then no price is acceptable to both and the company's optimal strategy is to commission additional research. The methods are illustrated using a recent example from the literature.

High-wafer-yield, high-performance vertical cavity surface-emitting lasers

NASA Astrophysics Data System (ADS)

Li, Gabriel S.; Yuen, Wupen; Lim, Sui F.; Chang-Hasnain, Constance J.

1996-04-01

Vertical cavity surface emitting lasers (VCSELs) with very low threshold current and voltage of 340 (mu) A and 1.5 V is achieved. The molecular beam epitaxially grown wafers are grown with a highly accurate, low cost and versatile pre-growth calibration technique. One- hundred percent VCSEL wafer yield is obtained. Low threshold current is achieved with a native oxide confined structure with excellent current confinement. Single transverse mode with stable, predetermined polarization direction up to 18 times threshold is also achieved, due to stable index guiding provided by the structure. This is the highest value reported to data for VCSELs. We have established that p-contact annealing in these devices is crucial for low voltage operation, contrary to the general belief. Uniform doping in the mirrors also appears not to be inferior to complicated doping engineering. With these design rules, very low threshold voltage VCSELs are achieved with very simple growth and fabrication steps.

Children with Auditory Neuropathy Spectrum Disorder Fitted with Hearing Aids Applying the American Academy of Audiology Pediatric Amplification Guideline: Current Practice and Outcomes.

PubMed

Walker, Elizabeth; McCreery, Ryan; Spratford, Meredith; Roush, Patricia

2016-03-01

Up to 15% of children with permanent hearing loss (HL) have auditory neuropathy spectrum disorder (ANSD), which involves normal outer hair cell function and disordered afferent neural activity in the auditory nerve or brainstem. Given the varying presentations of ANSD in children, there is a need for more evidence-based research on appropriate clinical interventions for this population. This study compared the speech production, speech perception, and language outcomes of children with ANSD, who are hard of hearing, to children with similar degrees of mild-to-moderately severe sensorineural hearing loss (SNHL), all of whom were fitted with bilateral hearing aids (HAs) based on the American Academy of Audiology pediatric amplification guidelines. Speech perception and communication outcomes data were gathered in a prospective accelerated longitudinal design, with entry into the study between six mo and seven yr of age. Three sites were involved in participant recruitment: Boys Town National Research Hospital, the University of North Carolina at Chapel Hill, and the University of Iowa. The sample consisted of 12 children with ANSD and 22 children with SNHL. The groups were matched based on better-ear pure-tone average, better-ear aided speech intelligibility index, gender, maternal education level, and newborn hearing screening result (i.e., pass or refer). Children and their families participated in an initial baseline visit, followed by visits twice a year for children <2 yr of age and once a yr for children >2 yr of age. Paired-sample t-tests were used to compare children with ANSD to children with SNHL. Paired t-tests indicated no significant differences between the ANSD and SNHL groups on language and articulation measures. Children with ANSD displayed functional speech perception skills in quiet. Although the number of participants was too small to conduct statistical analyses for speech perception testing, there appeared to be a trend in which the ANSD group performed more poorly in background noise with HAs, compared to the SNHL group. The American Academy of Audiology Pediatric Amplification Guidelines recommend that children with ANSD receive an HA trial if their behavioral thresholds are sufficiently high enough to impede speech perception at conversational levels. For children with ANSD in the mild-to-severe HL range, the current results support this recommendation, as children with ANSD can achieve functional outcomes similar to peers with SNHL. American Academy of Audiology.

Oil-in-Water Emulsion Exhibits Bitterness-Suppressing Effects in a Sensory Threshold Study.

PubMed

Torrico, Damir Dennis; Sae-Eaw, Amporn; Sriwattana, Sujinda; Boeneke, Charles; Prinyawiwatkul, Witoon

2015-06-01

Little is known about how emulsion characteristics affect saltiness/bitterness perception. Sensory detection and recognition thresholds of NaCl, caffeine, and KCl in aqueous solution compared with oil-in-water emulsion systems were evaluated. For emulsions, NaCl, KCl, or caffeine were dissolved in water + emulsifier and mixed with canola oil (20% by weight). Two emulsions were prepared: emulsion 1 (viscosity = 257 cP) and emulsion 2 (viscosity = 59 cP). The forced-choice ascending concentration series method of limits (ASTM E-679-04) was used to determine detection and/or recognition thresholds at 25 °C. Group best estimate threshold (GBET) geometric means were expressed as g/100 mL. Comparing NaCl with KCl, there were no significant differences in detection GBET values for all systems (0.0197 - 0.0354). For saltiness recognition thresholds, KCl GBET values were higher compared with NaCl GBET (0.0822 - 0.1070 compared with 0.0471 - 0.0501). For NaCl and KCl, emulsion 1 and/or emulsion 2 did not significantly affect the saltiness recognition threshold compared with that of the aqueous solution. However, the bitterness recognition thresholds of caffeine and KCl in solution were significantly lower than in the emulsions (0.0242 - 0.0586 compared with 0.0754 - 0.1025). Gender generally had a marginal effect on threshold values. This study showed that, compared with the aqueous solutions, emulsions did not significantly affect the saltiness recognition threshold of NaCl and KCl, but exhibited bitterness-suppressing effects on KCl and/or caffeine. © 2015 Institute of Food Technologists®

Unidirectional threshold switching in Ag/Si-based electrochemical metallization cells for high-density bipolar RRAM applications

NASA Astrophysics Data System (ADS)

Wang, Chao; Song, Bing; Li, Qingjiang; Zeng, Zhongming

2018-03-01

We herein present a novel unidirectional threshold selector for cross-point bipolar RRAM array. The proposed Ag/amorphous Si based threshold selector showed excellent threshold characteristics in positive field, such as high selectivity ( 105), steep slope (< 5 mV/decade) and low off-state current (< 300 pA). Meanwhile, the selector exhibited rectifying characteristics in the high resistance state as well and the rectification ratio was as high as 103 at ± 1.5 V. Nevertheless, due to the high reverse current about 9 mA at - 3 V, this unidirectional threshold selector can be used as a selection element for bipolar-type RRAM. By integrating a bipolar RRAM device with the selector, experiments showed that the undesired sneak was significantly suppressed, indicating its potentiality for high-density integrated nonvolatile memory applications.

Evidence for thermally assisted threshold switching behavior in nanoscale phase-change memory cells

NASA Astrophysics Data System (ADS)

Le Gallo, Manuel; Athmanathan, Aravinthan; Krebs, Daniel; Sebastian, Abu

2016-01-01

In spite of decades of research, the details of electrical transport in phase-change materials are still debated. In particular, the so-called threshold switching phenomenon that allows the current density to increase steeply when a sufficiently high voltage is applied is still not well understood, even though there is wide consensus that threshold switching is solely of electronic origin. However, the high thermal efficiency and fast thermal dynamics associated with nanoscale phase-change memory (PCM) devices motivate us to reassess a thermally assisted threshold switching mechanism, at least in these devices. The time/temperature dependence of the threshold switching voltage and current in doped Ge2Sb2Te5 nanoscale PCM cells was measured over 6 decades in time at temperatures ranging from 40 °C to 160 °C. We observe a nearly constant threshold switching power across this wide range of operating conditions. We also measured the transient dynamics associated with threshold switching as a function of the applied voltage. By using a field- and temperature-dependent description of the electrical transport combined with a thermal feedback, quantitative agreement with experimental data of the threshold switching dynamics was obtained using realistic physical parameters.

Method and system for controlling a rotational speed of a rotor of a turbogenerator

DOEpatents

Stahlhut, Ronnie Dean; Vuk, Carl Thomas

2008-12-30

A system and method controls a rotational speed of a rotor or shaft of a turbogenerator in accordance with a present voltage level on a direct current bus. A lower threshold and a higher threshold are established for a speed of a rotor or shaft of a turbogenerator. A speed sensor determines speed data or a speed signal for the rotor or shaft associated with a turbogenerator. A voltage regulator adjusts a voltage level associated with a direct current bus within a target voltage range if the speed data or speed signal indicates that the speed is above the higher threshold or below the lower threshold.

Associations among musculoskeletal impairments, depression, body image and fatigue in breast cancer survivors within the first year after treatment.

PubMed

Cantarero-Villanueva, I; Fernández-Lao, C; Fernández-DE-Las-Peñas, C; Díaz-Rodríguez, L; Sanchez-Cantalejo, E; Arroyo-Morales, M

2011-09-01

The aim of the current study was to investigate the relationship between pressure pain thresholds, shoulder movement, mood state, pain perception, muscle endurance, quality of life and fatigue in breast cancer survivors (BCS). Fifty-nine BCS reporting fatigue were examined at 6 months post-treatment. Women completed the Piper Fatigue Scale, the Breast Cancer-Specific Quality of Life Questionnaire, the Profile of Mood State, and neck-shoulder visual analogue scale. Additionally, shoulder flexion range of motion, the McQuade test (trunk flexor endurance) and pressure pain thresholds over the C5-C6 joint, the deltoid muscle, the second metacarpal and tibialis anterior muscle were assessed. Fatigue was greater in those patients with higher depression (r= 0.45, P < 0.05), higher shoulder pain (r= 0.39, P < 0.05), higher neck pain (r= 0.46, P < 0.01), lower body image (r=-0.34, P < 0.05) and reduced shoulder movement (r=-0.32, P < 0.05). Regression analyses demonstrated that depression, cervical pain intensity, body image and shoulder mobility were associated with fatigue (r= 0.55, P < 0.001). A psychological state characterised with higher depression and reduced body image and a physical impairment with higher cervical pain intensity and reduced shoulder mobility confirm multidimensional character of fatigue in BCS. © 2011 Blackwell Publishing Ltd.

Emotions in "Black and White" or Shades of Gray? How We Think About Emotion Shapes Our Perception and Neural Representation of Emotion.

PubMed

Satpute, Ajay B; Nook, Erik C; Narayanan, Sandhya; Shu, Jocelyn; Weber, Jochen; Ochsner, Kevin N

2016-11-01

The demands of social life often require categorically judging whether someone's continuously varying facial movements express "calm" or "fear," or whether one's fluctuating internal states mean one feels "good" or "bad." In two studies, we asked whether this kind of categorical, "black and white," thinking can shape the perception and neural representation of emotion. Using psychometric and neuroimaging methods, we found that (a) across participants, judging emotions using a categorical, "black and white" scale relative to judging emotions using a continuous, "shades of gray," scale shifted subjective emotion perception thresholds; (b) these shifts corresponded with activity in brain regions previously associated with affective responding (i.e., the amygdala and ventral anterior insula); and (c) connectivity of these regions with the medial prefrontal cortex correlated with the magnitude of categorization-related shifts. These findings suggest that categorical thinking about emotions may actively shape the perception and neural representation of the emotions in question. © The Author(s) 2016.

Emotions in ‘black or white’ or shades of gray? How we think about emotion shapes our perception and neural representation of emotion

PubMed Central

Satpute, Ajay B.; Nook, Erik C.; Narayanan, Sandhya; Shu, Jocelyn; Weber, Jochen; Ochsner, Kevin N.

2016-01-01

The demands of social life often require categorically judging whether someone's continuously varying facial movements express “calm” or “fear”, or whether our fluctuating internal states mean we feel “good” or “bad”. In two neuroimaging studies, we ask whether this kind of categorical, ‘black and white’, thinking can shape the perception and neural representation of emotion. Using psychometric and neuroimaging methods, we found that (1) across participants, judging emotions using a ‘black and white’ scale vs. a ‘shades of gray’ scale shifted subjective emotion perception thresholds, (2) these shifts corresponded with activity in regions associated with affective responding including the amygdala and ventral anterior insula, and (3) connectivity of these regions with the medial prefrontal cortex correlated with the magnitude of categorization-related shifts. These findings suggest that categorical thinking about emotion may actively shape the perception and neural representation of the emotions in question. PMID:27670663

Temporal Information Processing as a Basis for Auditory Comprehension: Clinical Evidence from Aphasic Patients

ERIC Educational Resources Information Center

Oron, Anna; Szymaszek, Aneta; Szelag, Elzbieta

2015-01-01

Background: Temporal information processing (TIP) underlies many aspects of cognitive functions like language, motor control, learning, memory, attention, etc. Millisecond timing may be assessed by sequencing abilities, e.g. the perception of event order. It may be measured with auditory temporal-order-threshold (TOT), i.e. a minimum time gap…

ePortfolio as Pedagogy: Threshold Concepts for Curriculum Design

ERIC Educational Resources Information Center

Lewis, Lyn

2017-01-01

The ePortfolio has been used in initial teacher education for its storage and presentation functions; however, its use as a pedagogic tool to enhance learning outcomes is less common. This study explored students' perceptions of ePortfolio and their learning in a Bachelor of Education (primary) programme at a New Zealand university. The research…

The Systems Approach to School Administration: Some Perceptions on the State of the Art in 1967.

ERIC Educational Resources Information Center

Knezevich, S. J.

Concepts which are salient features of the systems approach do not appear to have permeated school administration beyond the threshold of awareness. Confusion among administrators as to the meaning and potential of the systems approach can be partly attributed to its overzealous adherents, semantic difficulties among experts, and its application…

Towards a Better Understanding of Temporary Threshold Shift of Hearing.

DTIC Science & Technology

1980-03-01

recovery from TTS is influenced by drugs, medications, time of day, hypnosis , good thoughts or extra-sensory perception." I am only concerned in this...that is how our instrumentation works", to which may be added: "Because that is how we hear the loudness of noise." But are these sufficient reasons

Speech Perception with Music Maskers by Cochlear Implant Users and Normal-Hearing Listeners

ERIC Educational Resources Information Center

Eskridge, Elizabeth N.; Galvin, John J., III; Aronoff, Justin M.; Li, Tianhao; Fu, Qian-Jie

2012-01-01

Purpose: The goal of this study was to investigate how the spectral and temporal properties in background music may interfere with cochlear implant (CI) and normal-hearing listeners' (NH) speech understanding. Method: Speech-recognition thresholds (SRTs) were adaptively measured in 11 CI and 9 NH subjects. CI subjects were tested while using their…

Electric field characteristics of electroconvulsive therapy with individualized current amplitude: a preclinical study.

PubMed

Lee, Won Hee; Lisanby, Sarah H; Laine, Andrew F; Peterchev, Angel V

2013-01-01

This study examines the characteristics of the electric field induced in the brain by electroconvulsive therapy (ECT) with individualized current amplitude. The electric field induced by bilateral (BL), bifrontal (BF), right unilateral (RUL), and frontomedial (FM) ECT electrode configurations was computed in anatomically realistic finite element models of four nonhuman primates (NHPs). We generated maps of the electric field strength relative to an empirical neural activation threshold, and determined the stimulation strength and focality at fixed current amplitude and at individualized current amplitudes corresponding to seizure threshold (ST) measured in the anesthetized NHPs. The results show less variation in brain volume stimulated above threshold with individualized current amplitudes (16-36%) compared to fixed current amplitude (30-62%). Further, the stimulated brain volume at amplitude-titrated ST is substantially lower than that for ECT with conventional fixed current amplitudes. Thus individualizing the ECT stimulus current could compensate for individual anatomical variability and result in more focal and uniform electric field exposure across different subjects compared to the standard clinical practice of using high, fixed current for all patients.

Anxiety can significantly explain bolus perception in the context of hypotensive esophageal motility: Results of a large multicenter study in asymptomatic individuals.

PubMed

Cisternas, D; Scheerens, C; Omari, T; Monrroy, H; Hani, A; Leguizamo, A; Bilder, C; Ditaranto, A; Ruiz de León, A; Pérez de la Serna, J; Valdovinos, M A; Coello, R; Abrahao, L; Remes-Troche, J; Meixueiro, A; Zavala, M A; Marin, I; Serra, J

2017-09-01

Previous studies have not been able to correlate manometry findings with bolus perception. The aim of this study was to evaluate correlation of different variables, including traditional manometric variables (at diagnostic and extreme thresholds), esophageal shortening, bolus transit, automated impedance manometry (AIM) metrics and mood with bolus passage perception in a large cohort of asymptomatic individuals. High resolution manometry (HRM) was performed in healthy individuals from nine centers. Perception was evaluated using a 5-point Likert scale. Anxiety was evaluated using Hospitalized Anxiety and Depression scale (HAD). Subgroup analysis was also performed classifying studies into normal, hypotensive, vigorous, and obstructive patterns. One hundred fifteen studies were analyzed (69 using HRM and 46 using high resolution impedance manometry (HRIM); 3.5% swallows in 9.6% of volunteers were perceived. There was no correlation of any of the traditional HRM variables, esophageal shortening, AIM metrics nor bolus transit with perception scores. There was no HRM variable showing difference in perception when comparing normal vs extreme values (percentile 1 or 99). Anxiety but not depression was correlated with perception. Among hypotensive pattern, anxiety was a strong predictor of variance in perception (R 2 up to .70). Bolus perception is less common than abnormal motility among healthy individuals. Neither esophageal motor function nor bolus dynamics evaluated with several techniques seems to explain differences in bolus perception. Different mechanisms seem to be relevant in different manometric patterns. Anxiety is a significant predictor of bolus perception in the context of hypotensive motility. © 2017 John Wiley & Sons Ltd.

Characteristics of grouping colors for figure segregation on a multicolored background.

PubMed

Nagai, Takehiro; Uchikawa, Keiji

2008-11-01

A figure is segregated from its background when the colored elements belonging to the figure are grouped together. We investigated the range of color distribution conditions in which a figure could be segregated from its background using the color distribution differences. The stimulus was a multicolored texture composed of randomly shaped pieces. It was divided into two regions: a test region and a background region. The pieces in these two regions had different color distributions in the OSA Uniform Color Space. In our experiments, the subject segregated the figure of the test region using two different procedures. Since the Euclidean distance in the OSA Uniform Color Space corresponds to perceived color difference, if segregation thresholds are determined by only color difference, the thresholds should be independent of position and direction in the color space. In the results, however, the thresholds did depend on position and direction in the OSA Uniform Color Space. This suggests that color difference is not the only factor in figure segregation by color. Moreover, the threshold dependence on position and direction is influenced by the distances in the cone-opponent space whose axes are normalized by discrimination thresholds, suggesting that figure segregation threshold is determined by similar factors in the cone-opponent space for color discrimination. The analysis of the results by categorical color naming suggests that categorical color perception may affect figure segregation only slightly.

Intonation processing in congenital amusia: discrimination, identification and imitation.

PubMed

Liu, Fang; Patel, Aniruddh D; Fourcin, Adrian; Stewart, Lauren

2010-06-01

This study investigated whether congenital amusia, a neuro-developmental disorder of musical perception, also has implications for speech intonation processing. In total, 16 British amusics and 16 matched controls completed five intonation perception tasks and two pitch threshold tasks. Compared with controls, amusics showed impaired performance on discrimination, identification and imitation of statements and questions that were characterized primarily by pitch direction differences in the final word. This intonation-processing deficit in amusia was largely associated with a psychophysical pitch direction discrimination deficit. These findings suggest that amusia impacts upon one's language abilities in subtle ways, and support previous evidence that pitch processing in language and music involves shared mechanisms.

Are neural correlates of visual consciousness retinotopic?

PubMed

ffytche, Dominic H; Pins, Delphine

2003-11-14

Some visual neurons code what we see, their defining characteristic being a response profile which mirrors conscious percepts rather than veridical sensory attributes. One issue yet to be resolved is whether, within a given cortical area, conscious visual perception relates to diffuse activity across the entire population of such cells or focal activity within the sub-population mapping the location of the perceived stimulus. Here we investigate the issue in the human brain with fMRI, using a threshold stimulation technique to dissociate perceptual from non-perceptual activity. Our results point to a retinotopic organisation of perceptual activity in early visual areas, with independent perceptual activations for different regions of visual space.

Color difference thresholds in dentistry.

PubMed

Paravina, Rade D; Ghinea, Razvan; Herrera, Luis J; Bona, Alvaro D; Igiel, Christopher; Linninger, Mercedes; Sakai, Maiko; Takahashi, Hidekazu; Tashkandi, Esam; Perez, Maria del Mar

2015-01-01

The aim of this prospective multicenter study was to determine 50:50% perceptibility threshold (PT) and 50:50% acceptability threshold (AT) of dental ceramic under simulated clinical settings. The spectral radiance of 63 monochromatic ceramic specimens was determined using a non-contact spectroradiometer. A total of 60 specimen pairs, divided into 3 sets of 20 specimen pairs (medium to light shades, medium to dark shades, and dark shades), were selected for psychophysical experiment. The coordinating center and seven research sites obtained the Institutional Review Board (IRB) approvals prior the beginning of the experiment. Each research site had 25 observers, divided into five groups of five observers: dentists-D, dental students-S, dental auxiliaries-A, dental technicians-T, and lay persons-L. There were 35 observers per group (five observers per group at each site ×7 sites), for a total of 175 observers. Visual color comparisons were performed using a viewing booth. Takagi-Sugeno-Kang (TSK) fuzzy approximation was used for fitting the data points. The 50:50% PT and 50:50% AT were determined in CIELAB and CIEDE2000. The t-test was used to evaluate the statistical significance in thresholds differences. The CIELAB 50:50% PT was ΔEab  = 1.2, whereas 50:50% AT was ΔEab  = 2.7. Corresponding CIEDE2000 (ΔE00 ) values were 0.8 and 1.8, respectively. 50:50% PT by the observer group revealed differences among groups D, A, T, and L as compared with 50:50% PT for all observers. The 50:50% AT for all observers was statistically different than 50:50% AT in groups T and L. A 50:50% perceptibility and ATs were significantly different. The same is true for differences between two color difference formulas ΔE00 /ΔEab . Observer groups and sites showed high level of statistical difference in all thresholds. Visual color difference thresholds can serve as a quality control tool to guide the selection of esthetic dental materials, evaluate clinical performance, and interpret visual and instrumental findings in clinical dentistry, dental research, and subsequent standardization. The importance of quality control in dentistry is reinforced by increased esthetic demands of patients and dental professionals. © 2015 Wiley Periodicals, Inc.

Pixel structures to compensate nonuniform threshold voltage and mobility of polycrystalline silicon thin-film transistors using subthreshold current for large-size active matrix organic light-emitting diode displays

NASA Astrophysics Data System (ADS)

Na, Jun-Seok; Kwon, Oh-Kyong

2014-01-01

We propose pixel structures for large-size and high-resolution active matrix organic light-emitting diode (AMOLED) displays using a polycrystalline silicon (poly-Si) thin-film transistor (TFT) backplane. The proposed pixel structures compensate the variations of the threshold voltage and mobility of the driving TFT using the subthreshold current. The simulated results show that the emission current error of the proposed pixel structure B ranges from -2.25 to 2.02 least significant bit (LSB) when the variations of the threshold voltage and mobility of the driving TFT are ±0.5 V and ±10%, respectively.

Comparison of bimodal and bilateral cochlear implant users on speech recognition with competing talker, music perception, affective prosody discrimination, and talker identification.

PubMed

Cullington, Helen E; Zeng, Fan-Gang

2011-02-01

Despite excellent performance in speech recognition in quiet, most cochlear implant users have great difficulty with speech recognition in noise, music perception, identifying tone of voice, and discriminating different talkers. This may be partly due to the pitch coding in cochlear implant speech processing. Most current speech processing strategies use only the envelope information; the temporal fine structure is discarded. One way to improve electric pitch perception is to use residual acoustic hearing via a hearing aid on the nonimplanted ear (bimodal hearing). This study aimed to test the hypothesis that bimodal users would perform better than bilateral cochlear implant users on tasks requiring good pitch perception. Four pitch-related tasks were used. 1. Hearing in Noise Test (HINT) sentences spoken by a male talker with a competing female, male, or child talker. 2. Montreal Battery of Evaluation of Amusia. This is a music test with six subtests examining pitch, rhythm and timing perception, and musical memory. 3. Aprosodia Battery. This has five subtests evaluating aspects of affective prosody and recognition of sarcasm. 4. Talker identification using vowels spoken by 10 different talkers (three men, three women, two boys, and two girls). Bilateral cochlear implant users were chosen as the comparison group. Thirteen bimodal and 13 bilateral adult cochlear implant users were recruited; all had good speech perception in quiet. There were no significant differences between the mean scores of the bimodal and bilateral groups on any of the tests, although the bimodal group did perform better than the bilateral group on almost all tests. Performance on the different pitch-related tasks was not correlated, meaning that if a subject performed one task well they would not necessarily perform well on another. The correlation between the bimodal users' hearing threshold levels in the aided ear and their performance on these tasks was weak. Although the bimodal cochlear implant group performed better than the bilateral group on most parts of the four pitch-related tests, the differences were not statistically significant. The lack of correlation between test results shows that the tasks used are not simply providing a measure of pitch ability. Even if the bimodal users have better pitch perception, the real-world tasks used are reflecting more diverse skills than pitch. This research adds to the existing speech perception, language, and localization studies that show no significant difference between bimodal and bilateral cochlear implant users.

On the threshold conditions for electron beam damage of asbestos amosite fibers in the transmission electron microscope (TEM).

PubMed

Martin, Joannie; Beauparlant, Martin; Sauvé, Sébastien; L'Espérance, Gilles

2016-12-01

Asbestos amosite fibers were investigated to evaluate the damage caused by a transmission electron microscope (TEM) electron beam. Since elemental x-ray intensity ratios obtained by energy dispersive x-ray spectroscopy (EDS) are commonly used for asbestos identification, the impact of beam damage on these ratios was evaluated. It was determined that the magnesium/silicon ratio best represented the damage caused to the fiber. Various tests showed that most fibers have a current density threshold above which the chemical composition of the fiber is modified. The value of this threshold current density varied depending on the fiber, regardless of fiber diameter, and in some cases could not be determined. The existence of a threshold electron dose was also demonstrated. This value was dependent on the current density used and can be increased by providing a recovery period between exposures to the electron beam. This study also established that the electron beam current is directly related to the damage rate above a current density of 165 A/cm 2 . The large number of different results obtained suggest, that in order to ensure that the amosite fibers are not damaged, analysis should be conducted below a current density of 100 A/cm 2 .

Altered cortical and subcortical connectivity due to infrasound administered near the hearing threshold - Evidence from fMRI.

PubMed

Weichenberger, Markus; Bauer, Martin; Kühler, Robert; Hensel, Johannes; Forlim, Caroline Garcia; Ihlenfeld, Albrecht; Ittermann, Bernd; Gallinat, Jürgen; Koch, Christian; Kühn, Simone

2017-01-01

In the present study, the brain's response towards near- and supra-threshold infrasound (IS) stimulation (sound frequency < 20 Hz) was investigated under resting-state fMRI conditions. The study involved two consecutive sessions. In the first session, 14 healthy participants underwent a hearing threshold-as well as a categorical loudness scaling measurement in which the individual loudness perception for IS was assessed across different sound pressure levels (SPL). In the second session, these participants underwent three resting-state acquisitions, one without auditory stimulation (no-tone), one with a monaurally presented 12-Hz IS tone (near-threshold) and one with a similar tone above the individual hearing threshold corresponding to a 'medium loud' hearing sensation (supra-threshold). Data analysis mainly focused on local connectivity measures by means of regional homogeneity (ReHo), but also involved independent component analysis (ICA) to investigate inter-regional connectivity. ReHo analysis revealed significantly higher local connectivity in right superior temporal gyrus (STG) adjacent to primary auditory cortex, in anterior cingulate cortex (ACC) and, when allowing smaller cluster sizes, also in the right amygdala (rAmyg) during the near-threshold, compared to both the supra-threshold and the no-tone condition. Additional independent component analysis (ICA) revealed large-scale changes of functional connectivity, reflected in a stronger activation of the right amygdala (rAmyg) in the opposite contrast (no-tone > near-threshold) as well as the right superior frontal gyrus (rSFG) during the near-threshold condition. In summary, this study is the first to demonstrate that infrasound near the hearing threshold may induce changes of neural activity across several brain regions, some of which are known to be involved in auditory processing, while others are regarded as keyplayers in emotional and autonomic control. These findings thus allow us to speculate on how continuous exposure to (sub-)liminal IS could exert a pathogenic influence on the organism, yet further (especially longitudinal) studies are required in order to substantialize these findings.

Changes in taste preference and steps taken after sleep curtailment.

PubMed

Smith, Shannon L; Ludy, Mary-Jon; Tucker, Robin M

2016-09-01

A substantial proportion of the population does not achieve the recommended amount of sleep. Previous work demonstrates that sleep alterations perturb energy balance by disrupting appetite hormones, increasing energy intake, and decreasing physical activity. This study explored the influence of sleep duration on taste perception as well as effects on dietary intake and physical activity. Participants (n=24 habitual short sleepers and n=27 habitual long sleepers, 82.4% female, 88.2% white, 25.2±7.7years) completed two randomized taste visits; one following short sleep duration (≤7h) and one following long sleep duration (>7h). Taste perception measures included sweet and salt detection thresholds (ascending 3-alternative, forced-choice method), as well as sweet preference (Monell 2-series, forced-choice, paired-comparison, tracking method). Steps and sleep were tracked via FitBit, an activity monitoring device. Dietary intake was assessed using 24-hour recalls and analyzed using Nutritionist Pro. Habitual long-sleepers had a higher sweet taste preference (p=0.042) and took fewer steps (p=0.036) following sleep curtailment compared to the night where they slept >7h but did not experience changes in dietary intake or detection thresholds. Habitual short-sleepers did not experience changes in taste perception, activity, or dietary intake following sleep alteration. Habitual long-sleepers may be at greater risk of gaining weight when typical sleep patterns are disrupted. Copyright © 2016 Elsevier Inc. All rights reserved.

Prolonged maturation of auditory perception and learning in gerbils

PubMed Central

Sarro, Emma C.; Sanes, Dan H.

2011-01-01

In humans, auditory perception reaches maturity over a broad age range, extending through adolescence. Despite this slow maturation, children are considered to be outstanding learners, suggesting that immature perceptual skills might actually be advantageous to improvement on an acoustic task as a result of training (perceptual learning). Previous non-human studies have not employed an identical task when comparing perceptual performance of young and mature subjects, making it difficult to assess learning. Here, we used an identical procedure on juvenile and adult gerbils to examine the perception of amplitude modulation (AM), a stimulus feature that is an important component of most natural sounds. On average, Adult animals could detect smaller fluctuations in amplitude (i.e. smaller modulation depths) than Juveniles, indicating immature perceptual skills in Juveniles. However, the population variance was much greater for Juveniles, a few animals displaying adult-like AM detection. To determine whether immature perceptual skills facilitated learning, we compared naïve performance on the AM detection task with the amount of improvement following additional training. The amount of improvement in Adults correlated with naïve performance: those with the poorest naïve performance improved the most. In contrast, the naïve performance of Juveniles did not predict the amount of learning. Those Juveniles with immature AM detection thresholds did not display greater learning than Adults. Furthermore, for several of the Juveniles with adult-like thresholds, AM detection deteriorated with repeated testing. Thus, immature perceptual skills in young animals were not associated with greater learning. PMID:20506133

Exercise increases pressure pain tolerance but not pressure and heat pain thresholds in healthy young men.

PubMed

Vaegter, H B; Hoeger Bement, M; Madsen, A B; Fridriksson, J; Dasa, M; Graven-Nielsen, T

2017-01-01

Exercise causes an acute decrease in the pain sensitivity known as exercise-induced hypoalgesia (EIH), but the specificity to certain pain modalities remains unknown. This study aimed to compare the effect of isometric exercise on the heat and pressure pain sensitivity. On three different days, 20 healthy young men performed two submaximal isometric knee extensions (30% maximal voluntary contraction in 3 min) and a control condition (quiet rest). Before and immediately after exercise and rest, the sensitivity to heat pain and pressure pain was assessed in randomized and counterbalanced order. Cuff pressure pain threshold (cPPT) and pain tolerance (cPTT) were assessed on the ipsilateral lower leg by computer-controlled cuff algometry. Heat pain threshold (HPT) was recorded on the ipsilateral foot by a computer-controlled thermal stimulator. Cuff pressure pain tolerance was significantly increased after exercise compared with baseline and rest (p < 0.05). Compared with rest, cPPT and HPT were not significantly increased by exercise. No significant correlation between exercise-induced changes in HPT and cPPT was found. Test-retest reliability before and after the rest condition was better for cPPT and CPTT (intraclass correlation > 0.77) compared with HPT (intraclass correlation = 0.54). The results indicate that hypoalgesia after submaximal isometric exercise is primarily affecting tolerance of pressure pain compared with the pain threshold. These data contribute to the understanding of how isometric exercise influences pain perception, which is necessary to optimize the clinical utility of exercise in management of chronic pain. The effect of isometric exercise on pain tolerance may be relevant for patients in chronic musculoskeletal pain as a pain-coping strategy. WHAT DOES THIS STUDY ADD?: The results indicate that hypoalgesia after submaximal isometric exercise is primarily affecting tolerance of pressure pain compared with the heat and pressure pain threshold. These data contribute to the understanding of how isometric exercise influences pain perception, which is necessary to optimize the clinical utility of exercise in management of chronic pain. © 2016 European Pain Federation - EFIC®.

Defining indoor heat thresholds for health in the UK.

PubMed

Anderson, Mindy; Carmichael, Catriona; Murray, Virginia; Dengel, Andy; Swainson, Michael

2013-05-01

It has been recognised that as outdoor ambient temperatures increase past a particular threshold, so do mortality/morbidity rates. However, similar thresholds for indoor temperatures have not yet been identified. Due to a warming climate, the non-sustainability of air conditioning as a solution, and the desire for more energy-efficient airtight homes, thresholds for indoor temperature should be defined as a public health issue. The aim of this paper is to outline the need for indoor heat thresholds and to establish if they can be identified. Our objectives include: describing how indoor temperature is measured; highlighting threshold measurements and indices; describing adaptation to heat; summary of the risk of susceptible groups to heat; reviewing the current evidence on the link between sleep, heat and health; exploring current heat and health warning systems and thresholds; exploring the built environment and the risk of overheating; and identifying the gaps in current knowledge and research. A global literature search of key databases was conducted using a pre-defined set of keywords to retrieve peer-reviewed and grey literature. The paper will apply the findings to the context of the UK. A summary of 96 articles, reports, government documents and textbooks were analysed and a gap analysis was conducted. Evidence on the effects of indoor heat on health implies that buildings are modifiers of the effect of climate on health outcomes. Personal exposure and place-based heat studies showed the most significant correlations between indoor heat and health outcomes. However, the data are sparse and inconclusive in terms of identifying evidence-based definitions for thresholds. Further research needs to be conducted in order to provide an evidence base for threshold determination. Indoor and outdoor heat are related but are different in terms of language and measurement. Future collaboration between the health and building sectors is needed to develop a common language and an index for indoor heat and health thresholds in a changing climate.

Organisational Values in Higher Education: Perceptions and Preferences of Staff

ERIC Educational Resources Information Center

Kleijnen, Jan; Dolmans, Diana; Muijtjens, Arno; Willems, Jos; Van Hout, Hans

2009-01-01

In this paper, staff members' perceptions about the organisational culture are measured. The questions addressed are: what are their opinions about the current and preferred organisational culture? Are there differences between the current and preferred situation? Do the perceptions differ per department? The Organisational Culture Assessment…

Turkish Primary School Teachers' Perceptions of School Culture Regarding ICT Integration

ERIC Educational Resources Information Center

Tezci, Erdogan

2011-01-01

The current study aimed at identifying Turkish primary school teachers' perceptions of school culture regarding ICT integration in education. In addition, the current study was designed to investigate factors that might influence their perceptions. The participants were 1540 primary school teachers. The findings revealed that the teachers'…

The influence of current direction on phosphene thresholds evoked by transcranial magnetic stimulation.

PubMed

Kammer, T; Beck, S; Erb, M; Grodd, W

2001-11-01

To quantify phosphene thresholds evoked by transcranial magnetic stimulation (TMS) in the occipital cortex as a function of induced current direction. Phosphene thresholds were determined in 6 subjects. We compared two stimulator types (Medtronic-Dantec and Magstim) with monophasic pulses using the standard figure-of-eight coils and systematically varied hemisphere (left and right) and induced current direction (latero-medial and medio-lateral). Each measurement was made 3 times, with a new stimulation site chosen for each repetition. Only those stimulation sites were investigated where phosphenes were restricted to one visual hemifield. Coil positions were stereotactically registered. Functional magnetic resonance imaging (fMRI) of retinotopic areas was performed in 5 subjects to individually characterize the borders of visual areas; TMS stimulation sites were coregistered with respect to visual areas. Despite large interindividual variance we found a consistent pattern of phosphene thresholds. They were significantly lower if the direction of the induced current was oriented from lateral to medial in the occipital lobe rather than vice versa. No difference with respect to the hemisphere was found. Threshold values normalized to the square root of the stored energy in the stimulators were lower with the Medtronic-Dantec device than with the Magstim device. fMRI revealed that stimulation sites generating unilateral phosphenes were situated at V2 and V3. Variability of phosphene thresholds was low within a cortical patch of 2x2cm(2). Stimulation over V1 yields phosphenes in both visual fields. The excitability of visual cortical areas depends on the direction of the induced current with a preference for latero-medial currents. Although the coil positions used in this study were centered over visual areas V2 and V3, we cannot rule out the possibility that subcortical structures or V1 could actually be the main generator for phosphenes.

Effect of Heavy Consumption of Alcoholic Beverages on the Perception of Sweet and Salty Taste.

PubMed

Silva, Camile S; Dias, Vaneria R; Almeida, Juliane A Regis; Brazil, Jamile M; Santos, Ramon A; Milagres, Maria P

2016-05-01

To determine the threshold index of sweet and salty tastes in alcoholics undergoing treatment. Taste threshold was assessed using type 3-Alternative Forced Choice in a control group (92 non-alcoholic volunteers) and a test group (92 alcoholics in therapy). The test group completed a structured questionnaire on lifestyle and habits. Significant difference were found between the threshold rates found in the test (3.78) and control groups (1.39). In the salty stimulus, no significant difference was noted in the threshold detection between the control (0.17) and test groups (0.30). A significant correlation was observed between the index Pearson's threshold to sweet taste in the test group and their reported alcohol consumption. The test group reported characteristics such as loss of appetite (93%), weight loss during consumption (62%) and weight gain after quitting drinking (72%). That the alcoholic group reported less sensitivity to sweet taste suggests that drinking habits may influence choice of foods, with a greater preference for foods with higher sucrose concentration. This contribute to poor health, because excess consumption of sugar raises risk for several diseases. No conclusive results were found for the salty stimulus. © The Author 2015. Medical Council on Alcohol and Oxford University Press. All rights reserved.

Pain perception in major depressive disorder: a neurophysiological case-control study.

PubMed

Zambito Marsala, Sandro; Pistacchi, Michele; Tocco, Pierluigi; Gioulis, Manuela; Fabris, Federico; Brigo, Francesco; Tinazzi, Michele

2015-10-15

Depression and pain may sometimes be related conditions. Occasionally, depression may be associated with physical symptoms, such as back pain and headache. Moreover, depression may impair the subjective response to pain and is likely to influence the pain feeling. Conversely, chronic pain may represent an emotional condition as well as physical sensation, and can influence both the mood and behaviour. To better understand the relationship between pain and depression, we therefore assessed the pain threshold and the tolerance pain threshold in patients with depressive disorders. We conducted a case-control study and selected patients who had recently received a diagnosis of major depression (DSM-IV), before treatment, and without any significant pain complaints. Age- and sex-matched healthy controls were also included. Tactile and pain thresholds were assessed in all subjects through an electrical stimulation test. All results were compared between the groups. 27 patients and 27 age-matched healthy controls were included in the study. Tactile, pain and tolerance thresholds were evaluated in all subjects. The pain threshold and pain tolerance were lower in patients with major depression than controls. All differences were statistically significant (p<0.05). These results suggest the abnormal processing of pain stimuli in depressive disorders. Copyright © 2015 Elsevier B.V. All rights reserved.

Recruitment and Consolidation of Cell Assemblies for Words by Way of Hebbian Learning and Competition in a Multi-Layer Neural Network

PubMed Central

Garagnani, Max; Wennekers, Thomas; Pulvermüller, Friedemann

2009-01-01

Current cognitive theories postulate either localist representations of knowledge or fully overlapping, distributed ones. We use a connectionist model that closely replicates known anatomical properties of the cerebral cortex and neurophysiological principles to show that Hebbian learning in a multi-layer neural network leads to memory traces (cell assemblies) that are both distributed and anatomically distinct. Taking the example of word learning based on action-perception correlation, we document mechanisms underlying the emergence of these assemblies, especially (i) the recruitment of neurons and consolidation of connections defining the kernel of the assembly along with (ii) the pruning of the cell assembly’s halo (consisting of very weakly connected cells). We found that, whereas a learning rule mapping covariance led to significant overlap and merging of assemblies, a neurobiologically grounded synaptic plasticity rule with fixed LTP/LTD thresholds produced minimal overlap and prevented merging, exhibiting competitive learning behaviour. Our results are discussed in light of current theories of language and memory. As simulations with neurobiologically realistic neural networks demonstrate here spontaneous emergence of lexical representations that are both cortically dispersed and anatomically distinct, both localist and distributed cognitive accounts receive partial support. PMID:20396612

Recruitment and Consolidation of Cell Assemblies for Words by Way of Hebbian Learning and Competition in a Multi-Layer Neural Network.

PubMed

Garagnani, Max; Wennekers, Thomas; Pulvermüller, Friedemann

2009-06-01

Current cognitive theories postulate either localist representations of knowledge or fully overlapping, distributed ones. We use a connectionist model that closely replicates known anatomical properties of the cerebral cortex and neurophysiological principles to show that Hebbian learning in a multi-layer neural network leads to memory traces (cell assemblies) that are both distributed and anatomically distinct. Taking the example of word learning based on action-perception correlation, we document mechanisms underlying the emergence of these assemblies, especially (i) the recruitment of neurons and consolidation of connections defining the kernel of the assembly along with (ii) the pruning of the cell assembly's halo (consisting of very weakly connected cells). We found that, whereas a learning rule mapping covariance led to significant overlap and merging of assemblies, a neurobiologically grounded synaptic plasticity rule with fixed LTP/LTD thresholds produced minimal overlap and prevented merging, exhibiting competitive learning behaviour. Our results are discussed in light of current theories of language and memory. As simulations with neurobiologically realistic neural networks demonstrate here spontaneous emergence of lexical representations that are both cortically dispersed and anatomically distinct, both localist and distributed cognitive accounts receive partial support.

Evidence for thermally assisted threshold switching behavior in nanoscale phase-change memory cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Gallo, Manuel; Athmanathan, Aravinthan; Krebs, Daniel

2016-01-14

In spite of decades of research, the details of electrical transport in phase-change materials are still debated. In particular, the so-called threshold switching phenomenon that allows the current density to increase steeply when a sufficiently high voltage is applied is still not well understood, even though there is wide consensus that threshold switching is solely of electronic origin. However, the high thermal efficiency and fast thermal dynamics associated with nanoscale phase-change memory (PCM) devices motivate us to reassess a thermally assisted threshold switching mechanism, at least in these devices. The time/temperature dependence of the threshold switching voltage and current inmore » doped Ge{sub 2}Sb{sub 2}Te{sub 5} nanoscale PCM cells was measured over 6 decades in time at temperatures ranging from 40 °C to 160 °C. We observe a nearly constant threshold switching power across this wide range of operating conditions. We also measured the transient dynamics associated with threshold switching as a function of the applied voltage. By using a field- and temperature-dependent description of the electrical transport combined with a thermal feedback, quantitative agreement with experimental data of the threshold switching dynamics was obtained using realistic physical parameters.« less

How do musical tonality and experience affect visual working memory?

PubMed

Yang, Hua; Lu, Jing; Gong, Diankun; Yao, Dezhong

2016-01-20

The influence of music on the human brain has continued to attract increasing attention from neuroscientists and musicologists. Currently, tonal music is widely present in people's daily lives; however, atonal music has gradually become an important part of modern music. In this study, we conducted two experiments: the first one tested for differences in perception of distractibility between tonal music and atonal music. The second experiment tested how tonal music and atonal music affect visual working memory by comparing musicians and nonmusicians who were placed in contexts with background tonal music, atonal music, and silence. They were instructed to complete a delay matching memory task. The results show that musicians and nonmusicians have different evaluations of the distractibility of tonal music and atonal music, possibly indicating that long-term training may lead to a higher auditory perception threshold among musicians. For the working memory task, musicians reacted faster than nonmusicians in all background music cases, and musicians took more time to respond in the tonal background music condition than in the other conditions. Therefore, our results suggest that for a visual memory task, background tonal music may occupy more cognitive resources than atonal music or silence for musicians, leaving few resources left for the memory task. Moreover, the musicians outperformed the nonmusicians because of the higher sensitivity to background music, which also needs a further longitudinal study to be confirmed.

Auditory Outcomes with Hearing Rehabilitation in Children with Unilateral Hearing Loss: A Systematic Review.

PubMed

Appachi, Swathi; Specht, Jessica L; Raol, Nikhila; Lieu, Judith E C; Cohen, Michael S; Dedhia, Kavita; Anne, Samantha

2017-10-01

Objective Options for management of unilateral hearing loss (UHL) in children include conventional hearing aids, bone-conduction hearing devices, contralateral routing of signal (CROS) aids, and frequency-modulating (FM) systems. The objective of this study was to systematically review the current literature to characterize auditory outcomes of hearing rehabilitation options in UHL. Data Sources PubMed, EMBASE, Medline, CINAHL, and Cochrane Library were searched from inception to January 2016. Manual searches of bibliographies were also performed. Review Methods Studies analyzing auditory outcomes of hearing amplification in children with UHL were included. Outcome measures included functional and objective auditory results. Two independent reviewers evaluated each abstract and article. Results Of the 249 articles identified, 12 met inclusion criteria. Seven articles solely focused on outcomes with bone-conduction hearing devices. Outcomes favored improved pure-tone averages, speech recognition thresholds, and sound localization in implanted patients. Five studies focused on FM systems, conventional hearing aids, or CROS hearing aids. Limited data are available but suggest a trend toward improvement in speech perception with hearing aids. FM systems were shown to have the most benefit for speech recognition in noise. Studies evaluating CROS hearing aids demonstrated variable outcomes. Conclusions Data evaluating functional and objective auditory measures following hearing amplification in children with UHL are limited. Most studies do suggest improvement in speech perception, speech recognition in noise, and sound localization with a hearing rehabilitation device.

Broad-based visual benefits from training with an integrated perceptual-learning video game.

PubMed

Deveau, Jenni; Lovcik, Gary; Seitz, Aaron R

2014-06-01

Perception is the window through which we understand all information about our environment, and therefore deficits in perception due to disease, injury, stroke or aging can have significant negative impacts on individuals' lives. Research in the field of perceptual learning has demonstrated that vision can be improved in both normally seeing and visually impaired individuals, however, a limitation of most perceptual learning approaches is their emphasis on isolating particular mechanisms. In the current study, we adopted an integrative approach where the goal is not to achieve highly specific learning but instead to achieve general improvements to vision. We combined multiple perceptual learning approaches that have individually contributed to increasing the speed, magnitude and generality of learning into a perceptual-learning based video-game. Our results demonstrate broad-based benefits of vision in a healthy adult population. Transfer from the game includes; improvements in acuity (measured with self-paced standard eye-charts), improvement along the full contrast sensitivity function, and improvements in peripheral acuity and contrast thresholds. The use of this type of this custom video game framework built up from psychophysical approaches takes advantage of the benefits found from video game training while maintaining a tight link to psychophysical designs that enable understanding of mechanisms of perceptual learning and has great potential both as a scientific tool and as therapy to help improve vision. Copyright © 2014 Elsevier B.V. All rights reserved.

States of Awareness I: Subliminal Perception Relationship to Situational Awareness

DTIC Science & Technology

1993-05-01

one experiment, the visual detection threshold was raised by simultaneous auditory stimulation involving subliminal emotional words. Similar results...an assessment was made of the effects of both subliminal and supraliminal auditory accessory stimulation (white noise) on a visual detection task... stimulation investigation. Both subliminal and supraliminal auditory stimulation were employed to evaluate possible differential effects in visual illusions

The Sound and Feel of Titrations: A Smartphone Aid for Color-Blind and Visually Impaired Students

ERIC Educational Resources Information Center

Bandyopadhyay, Subhajit; Rathod, Balraj B.

2017-01-01

An Android-based application has been developed to provide color-blind and visually impaired students a multisensory perception of color change observed in a titration. The application records and converts the color information into beep sounds and vibration pulses, which are generated by the smartphone. It uses a range threshold of hue and…

The Mechanism of Speech Processing in Congenital Amusia: Evidence from Mandarin Speakers

PubMed Central

Liu, Fang; Jiang, Cunmei; Thompson, William Forde; Xu, Yi; Yang, Yufang; Stewart, Lauren

2012-01-01

Congenital amusia is a neuro-developmental disorder of pitch perception that causes severe problems with music processing but only subtle difficulties in speech processing. This study investigated speech processing in a group of Mandarin speakers with congenital amusia. Thirteen Mandarin amusics and thirteen matched controls participated in a set of tone and intonation perception tasks and two pitch threshold tasks. Compared with controls, amusics showed impaired performance on word discrimination in natural speech and their gliding tone analogs. They also performed worse than controls on discriminating gliding tone sequences derived from statements and questions, and showed elevated thresholds for pitch change detection and pitch direction discrimination. However, they performed as well as controls on word identification, and on statement-question identification and discrimination in natural speech. Overall, tasks that involved multiple acoustic cues to communicative meaning were not impacted by amusia. Only when the tasks relied mainly on pitch sensitivity did amusics show impaired performance compared to controls. These findings help explain why amusia only affects speech processing in subtle ways. Further studies on a larger sample of Mandarin amusics and on amusics of other language backgrounds are needed to consolidate these results. PMID:22347374

Probing the Electrode–Neuron Interface With Focused Cochlear Implant Stimulation

PubMed Central

Bierer, Julie Arenberg

2010-01-01

Cochlear implants are highly successful neural prostheses for persons with severe or profound hearing loss who gain little benefit from hearing aid amplification. Although implants are capable of providing important spectral and temporal cues for speech perception, performance on speech tests is variable across listeners. Psychophysical measures obtained from individual implant subjects can also be highly variable across implant channels. This review discusses evidence that such variability reflects deviations in the electrode–neuron interface, which refers to an implant channel's ability to effectively stimulate the auditory nerve. It is proposed that focused electrical stimulation is ideally suited to assess channel-to-channel irregularities in the electrode–neuron interface. In implant listeners, it is demonstrated that channels with relatively high thresholds, as measured with the tripolar configuration, exhibit broader psychophysical tuning curves and smaller dynamic ranges than channels with relatively low thresholds. Broader tuning implies that frequency-specific information intended for one population of neurons in the cochlea may activate more distant neurons, and a compressed dynamic range could make it more difficult to resolve intensity-based information, particularly in the presence of competing noise. Degradation of both types of cues would negatively affect speech perception. PMID:20724356

Predictive Coding or Evidence Accumulation? False Inference and Neuronal Fluctuations

PubMed Central

Friston, Karl J.; Kleinschmidt, Andreas

2010-01-01

Perceptual decisions can be made when sensory input affords an inference about what generated that input. Here, we report findings from two independent perceptual experiments conducted during functional magnetic resonance imaging (fMRI) with a sparse event-related design. The first experiment, in the visual modality, involved forced-choice discrimination of coherence in random dot kinematograms that contained either subliminal or periliminal motion coherence. The second experiment, in the auditory domain, involved free response detection of (non-semantic) near-threshold acoustic stimuli. We analysed fluctuations in ongoing neural activity, as indexed by fMRI, and found that neuronal activity in sensory areas (extrastriate visual and early auditory cortex) biases perceptual decisions towards correct inference and not towards a specific percept. Hits (detection of near-threshold stimuli) were preceded by significantly higher activity than both misses of identical stimuli or false alarms, in which percepts arise in the absence of appropriate sensory input. In accord with predictive coding models and the free-energy principle, this observation suggests that cortical activity in sensory brain areas reflects the precision of prediction errors and not just the sensory evidence or prediction errors per se. PMID:20369004

The mechanism of speech processing in congenital amusia: evidence from Mandarin speakers.

PubMed

Liu, Fang; Jiang, Cunmei; Thompson, William Forde; Xu, Yi; Yang, Yufang; Stewart, Lauren

2012-01-01

Congenital amusia is a neuro-developmental disorder of pitch perception that causes severe problems with music processing but only subtle difficulties in speech processing. This study investigated speech processing in a group of Mandarin speakers with congenital amusia. Thirteen Mandarin amusics and thirteen matched controls participated in a set of tone and intonation perception tasks and two pitch threshold tasks. Compared with controls, amusics showed impaired performance on word discrimination in natural speech and their gliding tone analogs. They also performed worse than controls on discriminating gliding tone sequences derived from statements and questions, and showed elevated thresholds for pitch change detection and pitch direction discrimination. However, they performed as well as controls on word identification, and on statement-question identification and discrimination in natural speech. Overall, tasks that involved multiple acoustic cues to communicative meaning were not impacted by amusia. Only when the tasks relied mainly on pitch sensitivity did amusics show impaired performance compared to controls. These findings help explain why amusia only affects speech processing in subtle ways. Further studies on a larger sample of Mandarin amusics and on amusics of other language backgrounds are needed to consolidate these results.