SLOWLY REPEATED EVOKED PAIN (SREP) AS A MARKER OF CENTRAL SENSITIZATION IN FIBROMYALGIA: DIAGNOSTIC ACCURACY AND RELIABILITY IN COMPARISON WITH TEMPORAL SUMMATION OF PAIN.

PubMed

de la Coba, Pablo; Bruehl, Stephen; Gálvez-Sánchez, Carmen María; Reyes Del Paso, Gustavo A

2018-05-01

This study examined the diagnostic accuracy and test-retest reliability of a novel dynamic evoked pain protocol (slowly repeated evoked pain; SREP) compared to temporal summation of pain (TSP), a standard index of central sensitization. Thirty-five fibromyalgia (FM) and 30 rheumatoid arthritis (RA) patients completed, in pseudorandomized order, a standard mechanical TSP protocol (10 stimuli of 1s duration at the thenar eminence using a 300g monofilament with 1s interstimulus interval) and the SREP protocol (9 suprathreshold pressure stimuli of 5s duration applied to the fingernail with a 30s interstimulus interval). In order to evaluate reliability for both protocols, they were repeated in a second session 4-7 days later. Evidence for significant pain sensitization over trials (increasing pain intensity ratings) was observed for SREP in FM (p<.001) but not in RA (p=.35), whereas significant sensitization was observed in both diagnostic groups for the TSP protocol (p's<.008). Compared to TSP, SREP demonstrated higher overall diagnostic accuracy (87.7% vs. 64.6%), greater sensitivity (0.89 vs. 0.57), and greater specificity (0.87 vs. 0.73) in discriminating between FM and RA patients. Test-retest reliability of SREP sensitization was good in FM (ICCs: 0.80), and moderate in RA (ICC: 0.68). SREP seems to be a dynamic evoked pain index tapping into pain sensitization that allows for greater diagnostic accuracy in identifying FM patients compared to a standard TSP protocol. Further research is needed to study mechanisms underlying SREP and the potential utility of adding SREP to standard pain evaluation protocols.

Neurophysiological correlates of abnormal somatosensory temporal discrimination in dystonia.

PubMed

Antelmi, Elena; Erro, Roberto; Rocchi, Lorenzo; Liguori, Rocco; Tinazzi, Michele; Di Stasio, Flavio; Berardelli, Alfredo; Rothwell, John C; Bhatia, Kailash P

2017-01-01

Somatosensory temporal discrimination threshold is often prolonged in patients with dystonia. Previous evidence suggested that this might be caused by impaired somatosensory processing in the time domain. Here, we tested if other markers of reduced inhibition in the somatosensory system might also contribute to abnormal somatosensory temporal discrimination in dystonia. Somatosensory temporal discrimination threshold was measured in 19 patients with isolated cervical dystonia and 19 age-matched healthy controls. We evaluated temporal somatosensory inhibition using paired-pulse somatosensory evoked potentials, spatial somatosensory inhibition by measuring the somatosensory evoked potentials interaction between simultaneous stimulation of the digital nerves in thumb and index finger, and Gamma-aminobutyric acid-ergic (GABAergic) sensory inhibition using the early and late components of high-frequency oscillations in digital nerves somatosensory evoked potentials. When compared with healthy controls, dystonic patients had longer somatosensory temporal discrimination thresholds, reduced suppression of cortical and subcortical paired-pulse somatosensory evoked potentials, less spatial inhibition of simultaneous somatosensory evoked potentials, and a smaller area of the early component of the high-frequency oscillations. A logistic regression analysis found that paired pulse suppression of the N20 component at an interstimulus interval of 5 milliseconds and the late component of the high-frequency oscillations were independently related to somatosensory temporal discrimination thresholds. "Dystonia group" was also a predictor of enhanced somatosensory temporal discrimination threshold, indicating a dystonia-specific effect that independently influences this threshold. Increased somatosensory temporal discrimination threshold in dystonia is related to reduced activity of inhibitory circuits within the primary somatosensory cortex. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

Somatosensory Temporal Discrimination Threshold Involves Inhibitory Mechanisms in the Primary Somatosensory Area.

PubMed

Rocchi, Lorenzo; Casula, Elias; Tocco, Pierluigi; Berardelli, Alfredo; Rothwell, John

2016-01-13

Somatosensory temporal discrimination threshold (STDT) is defined as the shortest time interval necessary for a pair of tactile stimuli to be perceived as separate. Although STDT is altered in several neurological disorders, its neural bases are not entirely clear. We used continuous theta burst stimulation (cTBS) to condition the excitability of the primary somatosensory cortex in healthy humans to examine its possible contribution to STDT. Excitability was assessed using the recovery cycle of the N20 component of somatosensory evoked potentials (SEP) and the area of high-frequency oscillations (HFO). cTBS increased STDT and reduced inhibition in the N20 recovery cycle at an interstimulus interval of 5 ms. It also reduced the amplitude of late HFO. All three effects were correlated. There was no effect of cTBS over the secondary somatosensory cortex on STDT, although it reduced the N120 component of the SEP. STDT is assessed conventionally with a simple ascending method. To increase insight into the effect of cTBS, we measured temporal discrimination with a psychophysical method. cTBS reduced the slope of the discrimination curve, consistent with a reduction of the quality of sensory information caused by an increase in noise. We hypothesize that cTBS reduces the effectiveness of inhibitory interactions normally used to sharpen temporal processing of sensory inputs. This reduction in discriminability of sensory input is equivalent to adding neural noise to the signal. Precise timing of sensory information is crucial for nearly every aspect of human perception and behavior. One way to assess the ability to analyze temporal information in the somatosensory domain is to measure the somatosensory temporal discrimination threshold (STDT), defined as the shortest time interval necessary for a pair of tactile stimuli to be perceived as separate. In this study, we found that STDT depends on inhibitory mechanisms within the primary somatosensory area (S1). This finding helps interpret the sensory processing deficits in neurological diseases, such as focal dystonia and Parkinson's disease, and possibly prompts future studies using neurostimulation techniques over S1 for therapeutic purposes in dystonic patients. Copyright © 2016 the authors 0270-6474/16/360325-11$15.00/0.

Selective attention and the auditory vertex potential. 1: Effects of stimulus delivery rate

NASA Technical Reports Server (NTRS)

Schwent, V. L.; Hillyard, S. A.; Galambos, R.

1975-01-01

Enhancement of the auditory vertex potentials with selective attention to dichotically presented tone pips was found to be critically sensitive to the range of inter-stimulus intervals in use. Only at the shortest intervals was a clear-cut enhancement of the latency component to stimuli observed for the attended ear.

Comparison of single bout effects of bicycle training versus locomotor training on paired reflex depression of the soleus H-reflex after motor incomplete spinal cord injury.

PubMed

Phadke, Chetan P; Flynn, Sheryl M; Thompson, Floyd J; Behrman, Andrea L; Trimble, Mark H; Kukulka, Carl G

2009-07-01

To examine paired reflex depression changes post 20-minute bout each of 2 training environments: stationary bicycle ergometer training (bicycle training) and treadmill with body weight support and manual assistance (locomotor training). Pretest-posttest repeated-measures. Locomotor laboratory. Motor incomplete SCI (n=12; mean, 44+/-16y); noninjured subjects (n=11; mean, 30.8+/-8.3y). All subjects received each type of training on 2 separate days. Paired reflex depression at different interstimulus intervals (10 s, 1 s, 500 ms, 200 ms, and 100 ms) was measured before and after both types of training. (1) Depression was significantly less post-SCI compared with noninjured subjects at all interstimulus intervals and (2) post-SCI at 100-millisecond interstimulus interval: reflex depression significantly increased postbicycle training in all SCI subjects and in the chronic and spastic subgroups (P<.05). Phase-dependent regulation of reflex excitability, essential to normal locomotion, coordinated by pre- and postsynaptic inhibitory processes (convergent action of descending and segmental inputs onto spinal circuits) is impaired post-SCI. Paired reflex depression provides a quantitative assay of inhibitory processes contributing to phase-dependent changes in reflex excitability. Because bicycle training normalized reflex depression, we propose that bicycling may have a potential role in walking rehabilitation, and future studies should examine the long-term effects on subclinical measures of reflex activity and its relationship to functional outcomes.

Strategy difficulty effects in young and older adults' episodic memory are modulated by inter-stimulus intervals and executive control processes.

PubMed

Burger, Lucile; Uittenhove, Kim; Lemaire, Patrick; Taconnat, Laurence

2017-04-01

Efficient execution of strategies is crucial to memory performance and to age-related differences in this performance. Relative strategy complexity influences memory performance and aging effects on memory. Here, we aimed to further our understanding of the effects of relative strategy complexity by looking at the role of cognitive control functions and the time-course of the effects of relative strategy complexity. Thus, we manipulated inter-stimulus intervals (ISI) and assessed executive functions. Results showed that (a) performance as a function of the relative strategy difficulty of the current and previous trial was modulated by ISI, (b) these effects were modulated by inhibition capacities, and (c) significant age differences were found in the way ISI modulates relative strategy difficulty. These findings have important implications for understanding the relationships between aging, executive control, and strategy execution in episodic memory. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of cognitive style and interstimulus interval on the hemispheric processing of tactile stimuli.

PubMed

Minagawa, N; Kashu, K

1989-06-01

16 adult subjects performed a tactile recognition task. According to our 1984 study, half of the subjects were classified as having a left hemispheric preference for the processing of visual stimuli, while the other half were classified as having a right hemispheric preference for the processing of visual stimuli. The present task was conducted according to the S1-S2 matching paradigm. The standard stimulus was a readily recognizable object and was presented tactually to either the left or right hand of each subject. The comparison stimulus was an object-picture and was presented visually by slide in a tachistoscope. The interstimulus interval was .05 sec. or 2.5 sec. Analysis indicated that the left-preference group showed right-hand superiority, and the right-preference group showed left-hand superiority. The notion of individual hemisphericity was supported in tactile processing.

An empirical comparison of SPM preprocessing parameters to the analysis of fMRI data.

PubMed

Della-Maggiore, Valeria; Chau, Wilkin; Peres-Neto, Pedro R; McIntosh, Anthony R

2002-09-01

We present the results from two sets of Monte Carlo simulations aimed at evaluating the robustness of some preprocessing parameters of SPM99 for the analysis of functional magnetic resonance imaging (fMRI). Statistical robustness was estimated by implementing parametric and nonparametric simulation approaches based on the images obtained from an event-related fMRI experiment. Simulated datasets were tested for combinations of the following parameters: basis function, global scaling, low-pass filter, high-pass filter and autoregressive modeling of serial autocorrelation. Based on single-subject SPM analysis, we derived the following conclusions that may serve as a guide for initial analysis of fMRI data using SPM99: (1) The canonical hemodynamic response function is a more reliable basis function to model the fMRI time series than HRF with time derivative. (2) Global scaling should be avoided since it may significantly decrease the power depending on the experimental design. (3) The use of a high-pass filter may be beneficial for event-related designs with fixed interstimulus intervals. (4) When dealing with fMRI time series with short interstimulus intervals (<8 s), the use of first-order autoregressive model is recommended over a low-pass filter (HRF) because it reduces the risk of inferential bias while providing a relatively good power. For datasets with interstimulus intervals longer than 8 seconds, temporal smoothing is not recommended since it decreases power. While the generalizability of our results may be limited, the methods we employed can be easily implemented by other scientists to determine the best parameter combination to analyze their data.

The effect of 1/f fluctuation in inter-stimulus intervals on auditory evoked mismatch field.

PubMed

Harada, Nobuyoshi; Masuda, Tadashi; Endo, Hiroshi; Nakamura, Yukihiro; Takeda, Tsunehiro; Tonoike, Mitsuo

2005-05-13

This study focused on the effect of regularity of environmental stimuli on the informational order extracting function of human brain. The regularity of environmental stimuli can be described with the exponent n of the fluctuation 1/f(n). We studied the effect of the exponent of the fluctuation in the inter-stimulus interval (ISI) on the elicitation of auditory evoked mismatch fields (MMF) with two sounds with alternating frequency. ISI times were given by three types of fluctuation, 1/f(0), 1/f(1), 1/f(2), and with a fixed interval (1/f(infinity)). The root mean square (RMS) value of the MMF increased significantly (F(3/9)=4.95, p=0.027) with increases in the exponent of the fluctuation. Increments in the regularity of the fluctuation provoked enhancement of the MMF, which reflected the production of a memory trace, based on the anticipation of the stimulus timing. The gradient of the curve, indicating the ratio of increments between the MMF and the exponent of fluctuation, can express a subject's capability to extract regularity from fluctuating stimuli.

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.

Neurophysiological and Behavioral Responses of Mandarin Lexical Tone Processing

PubMed Central

Yu, Yan H.; Shafer, Valerie L.; Sussman, Elyse S.

2017-01-01

Language experience enhances discrimination of speech contrasts at a behavioral- perceptual level, as well as at a pre-attentive level, as indexed by event-related potential (ERP) mismatch negativity (MMN) responses. The enhanced sensitivity could be the result of changes in acoustic resolution and/or long-term memory representations of the relevant information in the auditory cortex. To examine these possibilities, we used a short (ca. 600 ms) vs. long (ca. 2,600 ms) interstimulus interval (ISI) in a passive, oddball discrimination task while obtaining ERPs. These ISI differences were used to test whether cross-linguistic differences in processing Mandarin lexical tone are a function of differences in acoustic resolution and/or differences in long-term memory representations. Bisyllabic nonword tokens that differed in lexical tone categories were presented using a passive listening multiple oddball paradigm. Behavioral discrimination and identification data were also collected. The ERP results revealed robust MMNs to both easy and difficult lexical tone differences for both groups at short ISIs. At long ISIs, there was either no change or an enhanced MMN amplitude for the Mandarin group, but reduced MMN amplitude for the English group. In addition, the Mandarin listeners showed a larger late negativity (LN) discriminative response than the English listeners for lexical tone contrasts in the long ISI condition. Mandarin speakers outperformed English speakers in the behavioral tasks, especially under the long ISI conditions with the more similar lexical tone pair. These results suggest that the acoustic correlates of lexical tone are fairly robust and easily discriminated at short ISIs, when the auditory sensory memory trace is strong. At longer ISIs beyond 2.5 s language-specific experience is necessary for robust discrimination. PMID:28321179

Analysis and Synthesis of Adaptive Neural Elements and Assemblies

DTIC Science & Technology

1988-09-22

neuromodulation , has been identified in sensory neurons mediating the gill and tail withdrawal reflexes of Aplysia (Hawkins et al., 1983, Walters and... neuromodulation and predicted a characteristic interstimulus interval (ISI) curve (Gingrich and Byrne, 1987). At the subcellular level, the model’s ISI

Change detection and change blindness in pigeons (Columba livia).

PubMed

Herbranson, Walter T; Trinh, Yvan T; Xi, Patricia M; Arand, Mark P; Barker, Michael S K; Pratt, Theodore H

2014-05-01

Change blindness is a phenomenon in which even obvious details in a visual scene change without being noticed. Although change blindness has been studied extensively in humans, we do not yet know if it is a phenomenon that also occurs in other animals. Thus, investigation of change blindness in a nonhuman species may prove to be valuable by beginning to provide some insight into its ultimate causes. Pigeons learned a change detection task in which pecks to the location of a change in a sequence of stimulus displays were reinforced. They were worse at detecting changes if the stimulus displays were separated by a brief interstimulus interval, during which the display was blank, and this primary result matches the general pattern seen in previous studies of change blindness in humans. A second experiment attempted to identify specific stimulus characteristics that most reliably produced a failure to detect changes. Change detection was more difficult when interstimulus intervals were longer and when the change was iterated fewer times. ©2014 APA, all rights reserved.

A quantitative method for determining spatial discriminative capacity.

PubMed

Zhang, Zheng; Tannan, Vinay; Holden, Jameson K; Dennis, Robert G; Tommerdahl, Mark

2008-03-10

The traditional two-point discrimination (TPD) test, a widely used tactile spatial acuity measure, has been criticized as being imprecise because it is based on subjective criteria and involves a number of non-spatial cues. The results of a recent study showed that as two stimuli were delivered simultaneously, vibrotactile amplitude discrimination became worse when the two stimuli were positioned relatively close together and was significantly degraded when the probes were within a subject's two-point limen. The impairment of amplitude discrimination with decreasing inter-probe distance suggested that the metric of amplitude discrimination could possibly provide a means of objective and quantitative measurement of spatial discrimination capacity. A two alternative forced-choice (2AFC) tracking procedure was used to assess a subject's ability to discriminate the amplitude difference between two stimuli positioned at near-adjacent skin sites. Two 25 Hz flutter stimuli, identical except for a constant difference in amplitude, were delivered simultaneously to the hand dorsum. The stimuli were initially spaced 30 mm apart, and the inter-stimulus distance was modified on a trial-by-trial basis based on the subject's performance of discriminating the stimulus with higher intensity. The experiment was repeated via sequential, rather than simultaneous, delivery of the same vibrotactile stimuli. Results obtained from this study showed that the performance of the amplitude discrimination task was significantly degraded when the stimuli were delivered simultaneously and were near a subject's two-point limen. In contrast, subjects were able to correctly discriminate between the amplitudes of the two stimuli when they were sequentially delivered at all inter-probe distances (including those within the two-point limen), and improved when an adapting stimulus was delivered prior to simultaneously delivered stimuli. Subjects' capacity to discriminate the amplitude difference between two vibrotactile stimulations was degraded as the inter-stimulus distance approached the limit of their two-point spatial discriminative capacity. This degradation of spatial discriminative capacity lessened when an adapting stimulus was used. Performance of the task, as well as improvement on the task with adaptation, would most likely be impaired if the cortical information processing capacity of a subject or subject population were systemically altered, and thus, the methods described could be effective measures for use in clinical or clinical research applications.

Discrimination of speech and non-speech sounds following theta-burst stimulation of the motor cortex

PubMed Central

Rogers, Jack C.; Möttönen, Riikka; Boyles, Rowan; Watkins, Kate E.

2014-01-01

Perceiving speech engages parts of the motor system involved in speech production. The role of the motor cortex in speech perception has been demonstrated using low-frequency repetitive transcranial magnetic stimulation (rTMS) to suppress motor excitability in the lip representation and disrupt discrimination of lip-articulated speech sounds (Möttönen and Watkins, 2009). Another form of rTMS, continuous theta-burst stimulation (cTBS), can produce longer-lasting disruptive effects following a brief train of stimulation. We investigated the effects of cTBS on motor excitability and discrimination of speech and non-speech sounds. cTBS was applied for 40 s over either the hand or the lip representation of motor cortex. Motor-evoked potentials recorded from the lip and hand muscles in response to single pulses of TMS revealed no measurable change in motor excitability due to cTBS. This failure to replicate previous findings may reflect the unreliability of measurements of motor excitability related to inter-individual variability. We also measured the effects of cTBS on a listener’s ability to discriminate: (1) lip-articulated speech sounds from sounds not articulated by the lips (“ba” vs. “da”); (2) two speech sounds not articulated by the lips (“ga” vs. “da”); and (3) non-speech sounds produced by the hands (“claps” vs. “clicks”). Discrimination of lip-articulated speech sounds was impaired between 20 and 35 min after cTBS over the lip motor representation. Specifically, discrimination of across-category ba–da sounds presented with an 800-ms inter-stimulus interval was reduced to chance level performance. This effect was absent for speech sounds that do not require the lips for articulation and non-speech sounds. Stimulation over the hand motor representation did not affect discrimination of speech or non-speech sounds. These findings show that stimulation of the lip motor representation disrupts discrimination of speech sounds in an articulatory feature-specific way. PMID:25076928

Discrimination of speech and non-speech sounds following theta-burst stimulation of the motor cortex.

PubMed

Rogers, Jack C; Möttönen, Riikka; Boyles, Rowan; Watkins, Kate E

2014-01-01

Perceiving speech engages parts of the motor system involved in speech production. The role of the motor cortex in speech perception has been demonstrated using low-frequency repetitive transcranial magnetic stimulation (rTMS) to suppress motor excitability in the lip representation and disrupt discrimination of lip-articulated speech sounds (Möttönen and Watkins, 2009). Another form of rTMS, continuous theta-burst stimulation (cTBS), can produce longer-lasting disruptive effects following a brief train of stimulation. We investigated the effects of cTBS on motor excitability and discrimination of speech and non-speech sounds. cTBS was applied for 40 s over either the hand or the lip representation of motor cortex. Motor-evoked potentials recorded from the lip and hand muscles in response to single pulses of TMS revealed no measurable change in motor excitability due to cTBS. This failure to replicate previous findings may reflect the unreliability of measurements of motor excitability related to inter-individual variability. We also measured the effects of cTBS on a listener's ability to discriminate: (1) lip-articulated speech sounds from sounds not articulated by the lips ("ba" vs. "da"); (2) two speech sounds not articulated by the lips ("ga" vs. "da"); and (3) non-speech sounds produced by the hands ("claps" vs. "clicks"). Discrimination of lip-articulated speech sounds was impaired between 20 and 35 min after cTBS over the lip motor representation. Specifically, discrimination of across-category ba-da sounds presented with an 800-ms inter-stimulus interval was reduced to chance level performance. This effect was absent for speech sounds that do not require the lips for articulation and non-speech sounds. Stimulation over the hand motor representation did not affect discrimination of speech or non-speech sounds. These findings show that stimulation of the lip motor representation disrupts discrimination of speech sounds in an articulatory feature-specific way.

Abnormal tactile temporal discrimination in psychogenic dystonia.

PubMed

Morgante, F; Tinazzi, M; Squintani, G; Martino, D; Defazio, G; Romito, L; Albanese, A; Di Matteo, A; Quartarone, A; Girlanda, P; Fiorio, M; Berardelli, A

2011-09-20

Neurophysiologic studies demonstrated that patients with primary torsion dystonia (PTD) and with psychogenic dystonia (Psy-D) share similar abnormalities in the motor system. In this study, we evaluated somatosensory function in Psy-D by testing temporal discrimination threshold (TDT), and compared the results with those obtained in patients with PTD. TDT of tactile stimuli was assessed in 10 patients with Psy-D, 10 patients with PTD, and 16 control subjects. The 2 groups of patients were matched for age, gender, disease duration, and distribution of dystonia. Tactile stimuli consisted of pairs of non-noxious electrical shocks delivered to the right or left hand at interstimulus interval increasing from 0 to 400 msec, in 10-msec steps. TDT was defined as the value at which subjects recognized the 2 stimuli as asynchronous. TDT was higher in Psy-D and PTD compared to control subjects, for both the right and the left hand. In a subgroup of patients with unilateral dystonia (Psy-D = 4, PTD = 5), TDT did not differ between the affected and the unaffected side in both groups of patients. Disease duration was not correlated to the increased TDT value. Our study suggests an impaired processing of somatosensory inputs in both Psy-D and PTD. These abnormalities might represent a neurophysiological trait predisposing to develop a dystonic posture triggered by psychiatric and psychological factors.

Developing a New Quantitative Account of Backward Masking

ERIC Educational Resources Information Center

Francis, Gregory

2003-01-01

A new general explanation for u-shaped backward masking is analyzed and found to predict shifts in the interstimulus interval (ISI) that produces strongest masking. This predicted shift is then compared to six sets of masking data. The resulting comparisons force the general explanation to make certain assumptions to account for the data. In this…

Measuring Children's Attention Span: A Microcomputer Assessment Technique.

ERIC Educational Resources Information Center

Murphy-Berman, Virginia; And Others

1986-01-01

A microcomputer technique was used to measure the attention span of 115 boys and 117 girls in kindergarten through the ninth grade. Attentional ability increased only up through the fifth grade, and both the false alarm rate and the interstimulus interval scores were related to behavioral activity during test sessions. (Author/CB)

The influence of prior experience and expected timing on vibrotactile discrimination

PubMed Central

Karim, Muhsin; Harris, Justin A.; Langdon, Angela; Breakspear, Michael

2013-01-01

Vibrotactile discrimination tasks involve perceptual judgements on stimulus pairs separated by a brief interstimulus interval (ISI). Despite their apparent simplicity, decision making during these tasks is biased by prior experience in a manner that is not well understood. A striking example is when participants perform well on trials where the first stimulus is closer to the mean of the stimulus-set than the second stimulus, and perform comparatively poorly when the first stimulus is further from the stimulus mean. This “time-order effect” suggests that participants implicitly encode the mean of the stimulus-set and use this internal standard to bias decisions on any given trial. For relatively short ISIs, the magnitude of the time-order effect typically increases with the distance of the first stimulus from the global mean. Working from the premise that the time-order effect reflects the loss of precision in working memory representations, we predicted that the influence of the time-order effect, and this superimposed “distance” effect, would monotonically increase for trials with longer ISIs. However, by varying the ISI across four intervals (300, 600, 1200, and 2400 ms) we instead found a complex, non-linear dependence of the time-order effect on both the ISI and the distance, with the time-order effect being paradoxically stronger at short ISIs. We also found that this relationship depended strongly on participants' prior experience of the ISI (from previous task titration). The time-order effect not only depends on participants' expectations concerning the distribution of stimuli, but also on the expected timing of the trials. PMID:24399927

Selective attention and the auditory vertex potential. I - Effects of stimulus delivery rate. II - Effects of signal intensity and masking noise

NASA Technical Reports Server (NTRS)

Schwent, V. L.; Hillyard, S. A.; Galambos, R.

1976-01-01

The effects of varying the rate of delivery of dichotic tone pip stimuli on selective attention measured by evoked-potential amplitudes and signal detectability scores were studied. The subjects attended to one channel (ear) of tones, ignored the other, and pressed a button whenever occasional targets - tones of a slightly higher pitch were detected in the attended ear. Under separate conditions, randomized interstimulus intervals were short, medium, and long. Another study compared the effects of attention on the N1 component of the auditory evoked potential for tone pips presented alone and when white noise was added to make the tones barely above detectability threshold in a three-channel listening task. Major conclusions are that (1) N1 is enlarged to stimuli in an attended channel only in the short interstimulus interval condition (averaging 350 msec), (2) N1 and P3 are related to different modes of selective attention, and (3) attention selectivity in multichannel listening task is greater when tones are faint and/or difficult to detect.

Increased tissue oxygenation explains the attenuation of hyperemia upon repetitive pneumatic compression of the lower leg.

PubMed

Messere, Alessandro; Ceravolo, Gianluca; Franco, Walter; Maffiodo, Daniela; Ferraresi, Carlo; Roatta, Silvestro

2017-12-01

The rapid hyperemia evoked by muscle compression is short lived and was recently shown to undergo a rapid decrease even in spite of continuing mechanical stimulation. The present study aims at investigating the mechanisms underlying this attenuation, which include local metabolic mechanisms, desensitization of mechanosensitive pathways, and reduced efficacy of the muscle pump. In 10 healthy subjects, short sequences of mechanical compressions ( n = 3-6; 150 mmHg) of the lower leg were delivered at different interstimulus intervals (ranging from 20 to 160 s) through a customized pneumatic device. Hemodynamic monitoring included near-infrared spectroscopy, detecting tissue oxygenation and blood volume in calf muscles, and simultaneous echo-Doppler measurement of arterial (superficial femoral artery) and venous (femoral vein) blood flow. The results indicate that 1 ) a long-lasting (>100 s) increase in local tissue oxygenation follows compression-induced hyperemia, 2 ) compression-induced hyperemia exhibits different patterns of attenuation depending on the interstimulus interval, 3 ) the amplitude of the hyperemia is not correlated with the amount of blood volume displaced by the compression, and 4 ) the extent of attenuation negatively correlates with tissue oxygenation ( r  = -0,78, P < 0.05). Increased tissue oxygenation appears to be the key factor for the attenuation of hyperemia upon repetitive compressive stimulation. Tissue oxygenation monitoring is suggested as a useful integration in medical treatments aimed at improving local circulation by repetitive tissue compression. NEW & NOTEWORTHY This study shows that 1 ) the hyperemia induced by muscle compression produces a long-lasting increase in tissue oxygenation, 2 ) the hyperemia produced by subsequent muscle compressions exhibits different patterns of attenuation at different interstimulus intervals, and 3 ) the extent of attenuation of the compression-induced hyperemia is proportional to the level of oxygenation achieved in the tissue. The results support the concept that tissue oxygenation is a key variable in blood flow regulation. Copyright © 2017 the American Physiological Society.

The Crossmodal Facilitation of Visual Object Representations by Sound: Evidence from the Backward Masking Paradigm

ERIC Educational Resources Information Center

Chen, Yi-Chuan; Spence, Charles

2011-01-01

We report a series of experiments designed to demonstrate that the presentation of a sound can facilitate the identification of a concomitantly presented visual target letter in the backward masking paradigm. Two visual letters, serving as the target and its mask, were presented successively at various interstimulus intervals (ISIs). The results…

Magno and Parvo Stimuli Affect Illusory Directional Hearing in Normal and Dyslexic Readers

ERIC Educational Resources Information Center

Li, Winston; Meekins, Kelsey; Schirillo, James

2012-01-01

In an experimental paradigm adapted from Hari (1995), forty observers listened via headphones to 8 binaural clicks: 4 left-ear leading followed by 4 right-ear leading with either 38 or 140 ms interstimulus intervals (ISIs). Concurrently, they viewed either foveal or peripheral visual stimuli designed to activate either the parvocellular or…

Auditory Attentional Capture during Serial Recall: Violations at Encoding of an Algorithm-Based Neural Model?

ERIC Educational Resources Information Center

Hughes, Robert W.; Vachon, Francois; Jones, Dylan M.

2005-01-01

A novel attentional capture effect is reported in which visual-verbal serial recall was disrupted if a single deviation in the interstimulus interval occurred within otherwise regularly presented task-irrelevant spoken items. The degree of disruption was the same whether the temporal deviant was embedded in a sequence made up of a repeating item…

The Effect of Paired Muscle Stimulation on Preparation for Movement.

PubMed

Brownjohn, Philip W; Blakemore, Rebekah L; Fox, Jonathan A; Shemmell, Jonathan

2018-06-07

Paired muscle stimulation is used clinically to facilitate the performance of motor tasks for individuals with motor dysfunction. However, the optimal temporal relationship between stimuli for enhancing movement remains unknown. We hypothesized that synchronous, muscle stimulation would increase the extent to which stimulated muscles are concurrently prepared for movement. We validated a measure of muscle-specific changes in corticomotor excitability prior to movement. We used this measure to examine the preparation of the first dorsal interosseous (FDI), abductor digiti minimi (ADM), abductor pollicis brevis (APB) muscles prior to voluntary muscle contractions before and after paired muscle stimulation at four interstimulus intervals (0, 5, 10, and 75 ms). Paired muscle stimulation increased premovement excitability in the stimulated FDI, but not in the ADM muscle. Interstimulus interval was not a significant factor in determining efficacy of the protocol. Paired stimulation, therefore, did not result in a functional association being formed between the stimulated muscles. Somatosensory potentials evoked by the muscle stimuli were small compared to those commonly elicited by stimulation of peripheral nerves, suggesting that the lack of functional association formation between muscles may be due to the small magnitude of afferent volleys from the stimulated muscles, particularly the ADM, reaching the cortex.

Effects of linguistic experience on early levels of perceptual tone processing

NASA Astrophysics Data System (ADS)

Huang, Tsan; Johnson, Keith

2005-04-01

This study investigated the phenomenon of language-specificity in Mandarin Chinese tone perception. The main question was whether linguistic experience affects the earliest levels of perceptual processing of tones. Chinese and American English listeners participated in four perception experiments, which involved short inter-stimulus intervals (300 ms or 100 ms) and an AX discrimination or AX degree-of-difference rating task. Three experiments used natural speech monosyllabic tone stimuli and one experiment used time-varying sinusoidal simulations of Mandarin tones. AE listeners showed psychoacoustic listening in all experiments, paying much attention to onset and offset pitch. Chinese listeners showed language-specific patterns in all experiments to various degrees, where tonal neutralization rules reduced perceptual distance between two otherwise contrastive tones for Chinese listeners. Since these experiments employed procedures hypothesized to tap the auditory trace mode (Pisoni, Percept. Psychophys. 13, 253-260 (1973)], language-specificity found in this study seems to support the proposal of an auditory cortical map [Guenther et al., J. Acoust. Soc. Am. 23, 213-221 (1999)]. But the model needs refining to account for different degrees of language-specificity, which are better handled by Johnsons (2004, TLS03:26-41) lexical distance model, although the latter model is too rigid in assuming that linguistic experience does not affect low-level perceptual tasks such as AX discrimination with short ISIs.

The retention and disruption of color information in human short-term visual memory.

PubMed

Nemes, Vanda A; Parry, Neil R A; Whitaker, David; McKeefry, Declan J

2012-01-27

Previous studies have demonstrated that the retention of information in short-term visual perceptual memory can be disrupted by the presentation of masking stimuli during interstimulus intervals (ISIs) in delayed discrimination tasks (S. Magnussen & W. W. Greenlee, 1999). We have exploited this effect in order to determine to what extent short-term perceptual memory is selective for stimulus color. We employed a delayed hue discrimination paradigm to measure the fidelity with which color information was retained in short-term memory. The task required 5 color normal observers to discriminate between spatially non-overlapping colored reference and test stimuli that were temporally separated by an ISI of 5 s. The points of subjective equality (PSEs) on the resultant psychometric matching functions provided an index of performance. Measurements were made in the presence and absence of mask stimuli presented during the ISI, which varied in hue around the equiluminant plane in DKL color space. For all reference stimuli, we found a consistent mask-induced, hue-dependent shift in PSE compared to the "no mask" conditions. These shifts were found to be tuned in color space, only occurring for a range of mask hues that fell within bandwidths of 29-37 deg. Outside this range, masking stimuli had little or no effect on measured PSEs. The results demonstrate that memory masking for color exhibits selectivity similar to that which has already been demonstrated for other visual attributes. The relatively narrow tuning of these interference effects suggests that short-term perceptual memory for color is based on higher order, non-linear color coding. © ARVO

Timing in Trace Conditioning of the Nictitating Membrane Response of the Rabbit ("Oryctolagus Cuniculus"): Scalar, Nonscalar, and Adaptive Features

ERIC Educational Resources Information Center

Kehoe, E. James; Ludvig, Elliot A.; Sutton, Richard S.

2010-01-01

Using interstimulus intervals (ISIs) of 125, 250, and 500 msec in trace conditioning of the rabbit nictitating membrane response, the offset times and durations of conditioned responses (CRs) were collected along with onset and peak latencies. All measures were proportional to the ISI, but only onset and peak latencies conformed to the criterion…

The stability of M(max) and H (max) amplitude over time.

PubMed

McNulty, Penelope A; Shiner, Christine T; Thayaparan, Ganesha K; Burke, David

2012-05-01

The stability of the maximal muscle response (M(max)) is critical to H reflex methodology. It has previously been reported that the amplitude of M(max) declines over time. If reproducible, this finding would have implications for all experimental studies that normalise the output of the motoneurone pool against the M wave. We investigated the effect of time on changes in M(max) and the maximal H reflex (H(max)) evoked at 4-s intervals over 60 min. To identify an influence of homosynaptic depression, we extended the interstimulus interval to 10 s and the time to 100 min. Two recording montages over soleus were used to ensure that interelectrode distance was not a critical factor. The soleus M(max) and H reflex were evoked by stimulation of the tibial nerve in the popliteal fossa in 7 subjects who sat with the knee flexed to 30° and the ankle plantar flexed by ~30°. We found no change in the pooled data for M(max), H(max), a reflex 50% of maximal, or the current required to produce it. However, one subject had a statistically significant increase in M(max) and a concurrent decrease in H(max) regardless of the interstimulus interval. On average, there was no change in the H(max)/M(max) ratio over time. While both M(max) and H(max) may change in response to many factors, these results suggest that, typically, time is not one of them.

Complementary fMRI and EEG evidence for more efficient neural processing of rhythmic vs. unpredictably timed sounds

PubMed Central

van Atteveldt, Nienke; Musacchia, Gabriella; Zion-Golumbic, Elana; Sehatpour, Pejman; Javitt, Daniel C.; Schroeder, Charles

2015-01-01

The brain’s fascinating ability to adapt its internal neural dynamics to the temporal structure of the sensory environment is becoming increasingly clear. It is thought to be metabolically beneficial to align ongoing oscillatory activity to the relevant inputs in a predictable stream, so that they will enter at optimal processing phases of the spontaneously occurring rhythmic excitability fluctuations. However, some contexts have a more predictable temporal structure than others. Here, we tested the hypothesis that the processing of rhythmic sounds is more efficient than the processing of irregularly timed sounds. To do this, we simultaneously measured functional magnetic resonance imaging (fMRI) and electro-encephalograms (EEG) while participants detected oddball target sounds in alternating blocks of rhythmic (e.g., with equal inter-stimulus intervals) or random (e.g., with randomly varied inter-stimulus intervals) tone sequences. Behaviorally, participants detected target sounds faster and more accurately when embedded in rhythmic streams. The fMRI response in the auditory cortex was stronger during random compared to random tone sequence processing. Simultaneously recorded N1 responses showed larger peak amplitudes and longer latencies for tones in the random (vs. the rhythmic) streams. These results reveal complementary evidence for more efficient neural and perceptual processing during temporally predictable sensory contexts. PMID:26579044

Influence of inter-stimulus interval of spinal cord stimulation in patients with disorders of consciousness: A preliminary functional near-infrared spectroscopy study.

PubMed

Zhang, Yujin; Yang, Yi; Si, Juanning; Xia, Xiaoyu; He, Jianghong; Jiang, Tianzi

2018-01-01

Spinal cord stimulation (SCS) is a promising treatment for disorders of consciousness (DOC), but the underlying mechanism and most effective procedures remain uncertain. To optimize the protocol, previous studies evaluated the frequency-specific effects of SCS on neurophysiological activities. However, whether and how the inter-stimulus interval (ISI) parameter affects the SCS neuromodulation in DOC remains unknown. We enrolled nine DOC patients who had implanted SCS devices and conducted three different durations of ISIs. Using functional near-infrared spectroscopy (fNIRS), we monitored the blood volume fluctuations in the prefrontal and occipital cortices during the SCS. The results showed that short stimuli (30 s) induced significant cerebral blood volume changes, especially in the prefrontal cortex, an important area in the consciousness system. By comparing the mean value of the responses from the first and the last block in each session, a shorter ISI was found to improve the blood volume in the prefrontal cortex. This phenomenon was more significant for the subgroup of patients with a favorable prognosis. These preliminary results imply that the ISI may be an important factor for SCS. The research paradigm proposed here also provides insights for further quantitative evaluations of the therapeutic effects of neuromodulation.

Effects of interstimulus intervals on behavioral, heart rate, and event-related potential indices of infant engagement and sustained attention

PubMed Central

Xie, Wanze; Richards, John E.

2016-01-01

Maximizing infant attention to stimulus presentation during an EEG or ERP experiment is important for making valid inferences about the neural correlates of infant cognition. The present study examined the effects of stimulus presentation interstimulus interval (ISI) on behavioral and physiological indices of infant attention including infants’ fixation to visual presentation, the amount of heart rate (HR) change during sustained attention, and ERP components. This study compared an ISI that is typically used in infant EEG/ERP studies (e.g., 1,500–2,000 ms) with two shorter durations (400–600 ms and 600–1,000 ms). Thirty-six infants were tested cross-sectionally at 3, 4.5, and 6 months. It was found that using the short (400–600 ms) and medium (600–1,000 ms) ISIs resulted in more visually fixated trials and reduced frequency of fixation disengagement per experimental block. We also found larger HR changes during sustained attention to both of the shorter ISIs compared with the long ISI, and larger ERP responses when using the medium ISI compared to using the short and long ISIs. These data suggest that utilizing an optimal ISI (e.g., 600– 1,000 ms), which increases the presentation complexity and provides sufficient time for information processing, can promote infant engagement and sustained attention during stimulus presentation. PMID:27159263

Generalizing Over Conditions by Combining the Multitrait Multimethod Matrix and the Representative Design of Experiments,

DTIC Science & Technology

1986-01-01

by Anderson (1985) was reported in an article by Posner (1969) in which the difference in reaction time to an 1 "identity match" and a "name match...shorter reaction time) for the identity match but after a two-second [inter-stimulus) interval this * * advantage has almost completely disappeared. This...of critical sentences in a story. It is similar, however, in that reaction time was also used to evaluate differences between response categories that

The effects of the preferential 5-HT2A agonist psilocybin on prepulse inhibition of startle in healthy human volunteers depend on interstimulus interval.

PubMed

Vollenweider, Franz X; Csomor, Philipp A; Knappe, Bernhard; Geyer, Mark A; Quednow, Boris B

2007-09-01

Schizophrenia patients exhibit impairments in prepulse inhibition (PPI) of the startle response. Hallucinogenic 5-HT(2A) receptor agonists are used for animal models of schizophrenia because they mimic some symptoms of schizophrenia in humans and induce PPI deficits in animals. Nevertheless, one report indicates that the 5-HT(2A) receptor agonist psilocybin increases PPI in healthy humans. Hence, we investigated these inconsistent results by assessing the dose-dependent effects of psilocybin on PPI in healthy humans. Sixteen subjects each received placebo or 115, 215, and 315 microg/kg of psilocybin at 4-week intervals in a randomized and counterbalanced order. PPI at 30-, 60-, 120-, 240-, and 2000-ms interstimulus intervals (ISIs) was measured 90 and 165 min after drug intake, coinciding with the peak and post-peak effects of psilocybin. The effects of psilocybin on psychopathological core dimensions and sustained attention were assessed by the Altered States of Consciousness Rating Scale (5D-ASC) and the Frankfurt Attention Inventory (FAIR). Psilocybin dose-dependently reduced PPI at short (30 ms), had no effect at medium (60 ms), and increased PPI at long (120-2000 ms) ISIs, without affecting startle reactivity or habituation. Psilocybin dose-dependently impaired sustained attention and increased all 5D-ASC scores with exception of Auditory Alterations. Moreover, psilocybin-induced impairments in sustained attention performance were positively correlated with reduced PPI at the 30 ms ISI and not with the concomitant increases in PPI observed at long ISIs. These results confirm the psilocybin-induced increase in PPI at long ISIs and reveal that psilocybin also produces a decrease in PPI at short ISIs that is correlated with impaired attention and consistent with deficient PPI in schizophrenia.

Adaptation in the auditory midbrain of the barn owl (Tyto alba) induced by tonal double stimulation.

PubMed

Singheiser, Martin; Ferger, Roland; von Campenhausen, Mark; Wagner, Hermann

2012-02-01

During hunting, the barn owl typically listens to several successive sounds as generated, for example, by rustling mice. As auditory cells exhibit adaptive coding, the earlier stimuli may influence the detection of the later stimuli. This situation was mimicked with two double-stimulus paradigms, and adaptation was investigated in neurons of the barn owl's central nucleus of the inferior colliculus. Each double-stimulus paradigm consisted of a first or reference stimulus and a second stimulus (probe). In one paradigm (second level tuning), the probe level was varied, whereas in the other paradigm (inter-stimulus interval tuning), the stimulus interval between the first and second stimulus was changed systematically. Neurons were stimulated with monaural pure tones at the best frequency, while the response was recorded extracellularly. The responses to the probe were significantly reduced when the reference stimulus and probe had the same level and the inter-stimulus interval was short. This indicated response adaptation, which could be compensated for by an increase of the probe level of 5-7 dB over the reference level, if the latter was in the lower half of the dynamic range of a neuron's rate-level function. Recovery from adaptation could be best fitted with a double exponential showing a fast (1.25 ms) and a slow (800 ms) component. These results suggest that neurons in the auditory system show dynamic coding properties to tonal double stimulation that might be relevant for faithful upstream signal propagation. Furthermore, the overall stimulus level of the masker also seems to affect the recovery capabilities of auditory neurons. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Lateralization of Frequency-Specific Networks for Covert Spatial Attention to Auditory Stimuli

PubMed Central

Thorpe, Samuel; D'Zmura, Michael

2011-01-01

We conducted a cued spatial attention experiment to investigate the time–frequency structure of human EEG induced by attentional orientation of an observer in external auditory space. Seven subjects participated in a task in which attention was cued to one of two spatial locations at left and right. Subjects were instructed to report the speech stimulus at the cued location and to ignore a simultaneous speech stream originating from the uncued location. EEG was recorded from the onset of the directional cue through the offset of the inter-stimulus interval (ISI), during which attention was directed toward the cued location. Using a wavelet spectrum, each frequency band was then normalized by the mean level of power observed in the early part of the cue interval to obtain a measure of induced power related to the deployment of attention. Topographies of band specific induced power during the cue and inter-stimulus intervals showed peaks over symmetric bilateral scalp areas. We used a bootstrap analysis of a lateralization measure defined for symmetric groups of channels in each band to identify specific lateralization events throughout the ISI. Our results suggest that the deployment and maintenance of spatially oriented attention throughout a period of 1,100 ms is marked by distinct episodes of reliable hemispheric lateralization ipsilateral to the direction in which attention is oriented. An early theta lateralization was evident over posterior parietal electrodes and was sustained throughout the ISI. In the alpha and mu bands punctuated episodes of parietal power lateralization were observed roughly 500 ms after attentional deployment, consistent with previous studies of visual attention. In the beta band these episodes show similar patterns of lateralization over frontal motor areas. These results indicate that spatial attention involves similar mechanisms in the auditory and visual modalities. PMID:21630112

Participation of the Classical Speech Areas in Auditory Long-Term Memory

PubMed Central

Karabanov, Anke Ninija; Paine, Rainer; Chao, Chi Chao; Schulze, Katrin; Scott, Brian; Hallett, Mark; Mishkin, Mortimer

2015-01-01

Accumulating evidence suggests that storing speech sounds requires transposing rapidly fluctuating sound waves into more easily encoded oromotor sequences. If so, then the classical speech areas in the caudalmost portion of the temporal gyrus (pSTG) and in the inferior frontal gyrus (IFG) may be critical for performing this acoustic-oromotor transposition. We tested this proposal by applying repetitive transcranial magnetic stimulation (rTMS) to each of these left-hemisphere loci, as well as to a nonspeech locus, while participants listened to pseudowords. After 5 minutes these stimuli were re-presented together with new ones in a recognition test. Compared to control-site stimulation, pSTG stimulation produced a highly significant increase in recognition error rate, without affecting reaction time. By contrast, IFG stimulation led only to a weak, non-significant, trend toward recognition memory impairment. Importantly, the impairment after pSTG stimulation was not due to interference with perception, since the same stimulation failed to affect pseudoword discrimination examined with short interstimulus intervals. Our findings suggest that pSTG is essential for transforming speech sounds into stored motor plans for reproducing the sound. Whether or not the IFG also plays a role in speech-sound recognition could not be determined from the present results. PMID:25815813

Participation of the classical speech areas in auditory long-term memory.

PubMed

Karabanov, Anke Ninija; Paine, Rainer; Chao, Chi Chao; Schulze, Katrin; Scott, Brian; Hallett, Mark; Mishkin, Mortimer

2015-01-01

Accumulating evidence suggests that storing speech sounds requires transposing rapidly fluctuating sound waves into more easily encoded oromotor sequences. If so, then the classical speech areas in the caudalmost portion of the temporal gyrus (pSTG) and in the inferior frontal gyrus (IFG) may be critical for performing this acoustic-oromotor transposition. We tested this proposal by applying repetitive transcranial magnetic stimulation (rTMS) to each of these left-hemisphere loci, as well as to a nonspeech locus, while participants listened to pseudowords. After 5 minutes these stimuli were re-presented together with new ones in a recognition test. Compared to control-site stimulation, pSTG stimulation produced a highly significant increase in recognition error rate, without affecting reaction time. By contrast, IFG stimulation led only to a weak, non-significant, trend toward recognition memory impairment. Importantly, the impairment after pSTG stimulation was not due to interference with perception, since the same stimulation failed to affect pseudoword discrimination examined with short interstimulus intervals. Our findings suggest that pSTG is essential for transforming speech sounds into stored motor plans for reproducing the sound. Whether or not the IFG also plays a role in speech-sound recognition could not be determined from the present results.

Learning to perceive differences in solid shape through vision and touch.

PubMed

Norman, J Farley; Clayton, Anna Marie; Norman, Hideko F; Crabtree, Charles E

2008-01-01

A single experiment was designed to investigate perceptual learning and the discrimination of 3-D object shape. Ninety-six observers were presented with naturally shaped solid objects either visually, haptically, or across the modalities of vision and touch. The observers' task was to judge whether the two sequentially presented objects on any given trial possessed the same or different 3-D shapes. The results of the experiment revealed that significant perceptual learning occurred in all modality conditions, both unimodal and cross-modal. The amount of the observers' perceptual learning, as indexed by increases in hit rate and d', was similar for all of the modality conditions. The observers' hit rates were highest for the unimodal conditions and lowest in the cross-modal conditions. Lengthening the inter-stimulus interval from 3 to 15 s led to increases in hit rates and decreases in response bias. The results also revealed the existence of an asymmetry between two otherwise equivalent cross-modal conditions: in particular, the observers' perceptual sensitivity was higher for the vision-haptic condition and lower for the haptic-vision condition. In general, the results indicate that effective cross-modal shape comparisons can be made between the modalities of vision and active touch, but that complete information transfer does not occur.

Somatosensory evoked potentials in patients with hypocalcaemia after parathyroidectomy.

PubMed

Kanda, F; Jinnai, J; Fujita, T

1988-01-01

The effects of hypocalcaemia on somatosensory evoked potentials (SEPs) were studied in five patients after parathyroidectomy. Despite normal latencies the mean value of amplitudes of the SEPs in hypocalcaemic patients was greater than that in normocalcaemic subjects. Recovery functions of the SEPs showed a significant decrease in hypocalcaemic patients at interstimulus intervals of about 10 ms compared with those in normocalcaemic patients and in normal volunteers. Recovery functions appear to be a valid indicator of synaptic efficacy, especially for evaluation of the reduction in conduction efficacy of the central nervous system in hypocalcaemia.

Dissociating Long and Short-term Memory in Three-Month-Old Infants Using the Mismatch Response to Voice Stimuli

PubMed Central

Zinke, Katharina; Thöne, Leonie; Bolinger, Elaina M.; Born, Jan

2018-01-01

Auditory event-related potentials (ERPs) have been successfully used in adults as well as in newborns to discriminate recall of longer-term and shorter-term memories. Specifically the Mismatch Response (MMR) to deviant stimuli of an oddball paradigm is larger if the deviant stimuli are highly familiar (i.e., retrieved from long-term memory) than if they are unfamiliar, representing an immediate change to the standard stimuli kept in short-term memory. Here, we aimed to extend previous findings indicating a differential MMR to familiar and unfamiliar deviants in newborns (Beauchemin et al., 2011), to 3-month-old infants who are starting to interact more with their social surroundings supposedly based on forming more (social) long-term representations. Using a voice discrimination paradigm, each infant was repeatedly presented with the word “baby” (400 ms, interstimulus interval: 600 ms, 10 min overall duration) pronounced by three different female speakers. One voice that was unfamiliar to the infants served as the frequently presented “standard” stimulus, whereas another unfamiliar voice served as the “unfamiliar deviant” stimulus, and the voice of the infant’s mother served as the “familiar deviant.” Data collection was successful for 31 infants (mean age = 100 days). The MMR was determined by the difference between the ERP to standard stimuli and the ERP to the unfamiliar and familiar deviant, respectively. The MMR to the familiar deviant (mother’s voice) was larger, i.e., more positive, than that to the unfamiliar deviant between 100 and 400 ms post-stimulus over the frontal and central cortex. However, a genuine MMR differentiating, as a positive deflection, between ERPs to familiar deviants and standard stimuli was only found in the 300–400 ms interval. On the other hand, a genuine MMR differentiating, as a negative deflection, between ERPs to unfamiliar deviants from ERPs to standard stimuli was revealed for the 200–300 ms post-stimulus interval. Overall results confirm a differential MMR response to unfamiliar and familiar deviants in 3-month-olds, with the earlier negative MMR to unfamiliar deviants likely reflecting change detection based on comparison processes in short-term memory, and the later positive MMR to familiar deviants reflecting subsequent long-term memory-based processing of stimulus relevance. PMID:29441032

Dissociating Long and Short-term Memory in Three-Month-Old Infants Using the Mismatch Response to Voice Stimuli.

PubMed

Zinke, Katharina; Thöne, Leonie; Bolinger, Elaina M; Born, Jan

2018-01-01

Auditory event-related potentials (ERPs) have been successfully used in adults as well as in newborns to discriminate recall of longer-term and shorter-term memories. Specifically the Mismatch Response (MMR) to deviant stimuli of an oddball paradigm is larger if the deviant stimuli are highly familiar (i.e., retrieved from long-term memory) than if they are unfamiliar, representing an immediate change to the standard stimuli kept in short-term memory. Here, we aimed to extend previous findings indicating a differential MMR to familiar and unfamiliar deviants in newborns (Beauchemin et al., 2011), to 3-month-old infants who are starting to interact more with their social surroundings supposedly based on forming more (social) long-term representations. Using a voice discrimination paradigm, each infant was repeatedly presented with the word "baby" (400 ms, interstimulus interval: 600 ms, 10 min overall duration) pronounced by three different female speakers. One voice that was unfamiliar to the infants served as the frequently presented "standard" stimulus, whereas another unfamiliar voice served as the "unfamiliar deviant" stimulus, and the voice of the infant's mother served as the "familiar deviant." Data collection was successful for 31 infants (mean age = 100 days). The MMR was determined by the difference between the ERP to standard stimuli and the ERP to the unfamiliar and familiar deviant, respectively. The MMR to the familiar deviant (mother's voice) was larger, i.e., more positive, than that to the unfamiliar deviant between 100 and 400 ms post-stimulus over the frontal and central cortex. However, a genuine MMR differentiating, as a positive deflection, between ERPs to familiar deviants and standard stimuli was only found in the 300-400 ms interval. On the other hand, a genuine MMR differentiating, as a negative deflection, between ERPs to unfamiliar deviants from ERPs to standard stimuli was revealed for the 200-300 ms post-stimulus interval. Overall results confirm a differential MMR response to unfamiliar and familiar deviants in 3-month-olds, with the earlier negative MMR to unfamiliar deviants likely reflecting change detection based on comparison processes in short-term memory, and the later positive MMR to familiar deviants reflecting subsequent long-term memory-based processing of stimulus relevance.

Modulation of somatosensory evoked potentials during wake-sleep states and spike-wave discharges in the rat.

PubMed

Shaw, Fu-Zen; Lee, Su-Ying; Chiu, Ted H

2006-03-01

To clarify the cortical evoked responses in the primary somatosensory cortex of the rat under states of waking, slow-wave sleep (SWS), paradoxical sleep (PS), and spike-wave discharges (SWDs), which are associated with absence seizure. Somatosensory evoked potentials (SEPs) in response to single- and paired-pulse stimulations under waking, SWS, PS, and SWDs were compared. SEPs to a single-pulse stimulus with regard to cortical spikes of sleep spindles and SWDs were also evaluated. Twenty Long Evans rats. Single- and paired-pulse innocuous electrical stimulations were applied to the tail of rats with chronically implanted electrodes in the primary somatosensory cortex and neck muscle under waking, SWS, PS, and SWDs. SEPs displayed distinct patterns under waking/PS and SWS/SWDs. The short-latency P1-N1 wave of the SEP was severely impeded during SWDs but not in other states. Reduction of the P1-N1 magnitude to the second stimulus of the paired-pulse stimulus for interstimulus intervals of < or = 300 milliseconds appeared in waking and PS states, but the decrease occurred only at particular interstimulus intervals under SWS. Interestingly, augmentation was found under SWDs. Moreover, cyclic augmentation of the P1-N1 magnitude was associated with spindle spikes, but cyclic reduction was observed with SWD spikes. Changes in SEPs are not only behavior dependent, but also phase locked onto ongoing brain activity. Distinct short-term plasticity of SEPs during sleep spindles or SWDs may merit further studies for seizure control and tactile information processing.

The Amount of Time Dilation for Visual Flickers Corresponds to the Amount of Neural Entrainments Measured by EEG.

PubMed

Hashimoto, Yuki; Yotsumoto, Yuko

2018-01-01

The neural basis of time perception has long attracted the interests of researchers. Recently, a conceptual model consisting of neural oscillators was proposed and validated by behavioral experiments that measured the dilated duration in perception of a flickering stimulus (Hashimoto and Yotsumoto, 2015). The model proposed that flickering stimuli cause neural entrainment of oscillators, resulting in dilated time perception. In this study, we examined the oscillator-based model of time perception, by collecting electroencephalography (EEG) data during an interval-timing task. Initially, subjects observed a stimulus, either flickering at 10-Hz or constantly illuminated. The subjects then reproduced the duration of the stimulus by pressing a button. As reported in previous studies, the subjects reproduced 1.22 times longer durations for flickering stimuli than for continuously illuminated stimuli. The event-related potential (ERP) during the observation of a flicker oscillated at 10 Hz, reflecting the 10-Hz neural activity phase-locked to the flicker. Importantly, the longer reproduced duration was associated with a larger amplitude of the 10-Hz ERP component during the inter-stimulus interval, as well as during the presentation of the flicker. The correlation between the reproduced duration and the 10-Hz oscillation during the inter-stimulus interval suggested that the flicker-induced neural entrainment affected time dilation. While the 10-Hz flickering stimuli induced phase-locked entrainments at 10 Hz, we also observed event-related desynchronizations of spontaneous neural oscillations in the alpha-frequency range. These could be attributed to the activation of excitatory neurons while observing the flicker stimuli. In addition, neural activity at approximately the alpha frequency increased during the reproduction phase, indicating that flicker-induced neural entrainment persisted even after the offset of the flicker. In summary, our results suggest that the duration perception is mediated by neural oscillations, and that time dilation induced by flickering visual stimuli can be attributed to neural entrainment.

Functional plasticity in the interposito-thalamo-cortical pathway during conditioning. Role of the interstimulus interval.

PubMed

Pananceau, M; Rispal-Padel, L

2000-06-01

In classic conditioning, the interstimulus interval (ISI) between the conditioned (CS) and unconditioned (US) stimulus is a critical parameter. The aim of the present experiment was to assess whether, during conditioning, modification of the CS-US interval could reliably produce changes in the functional properties of the interposito-thalamo-cortical pathways (INTCps). Five cats were prepared for chronic stimulation and recording from several brain regions along this pathway in awake animals. The CS was a weak electric shock applied on the interposed nucleus of the cerebellum in sites that initially elicited forelimb flexion (i.e., alpha motor responses) in three cats, and equal proportions of flexor and extensor responses in two cats. The US was an electric shock applied on the skin that elicited forelimb flexions. The motor and neurobiological effects of synchronous CS-US were compared with pairings in which the CS was applied 100 ms before US. Simultaneous and sequential application of CS and US produced different behavioral outcomes and resulted in different neural processes in the interposito-thalamo-cortical pathways (INTCps). The simultaneous presentation of stimuli only produced a small increase in excitability spreading to all the body representational zones of the primary motor cortex and a weak increase in the amplitude of the alpha motor response. In contrast, the sequential application led to a profound modification of the interposed output to neurons in the forelimb representation of the motor cortex. These robust neuronal correlates of conditioning were accompanied by a large facilitation of the alpha motor response (alpha-MR). There were also changes in the direction of misdirected alpha responses and an emergence of functionally appropriate, long-latency withdrawal forelimb flexion. These data revealed that, during conditioning, plastic changes within the thalamocortical connections are selectively induced by sequential information from central and peripheral afferents. This sequence significantly contributed to neural processes that are responsible for the acquisition, expression, and extinction of anticipatory flexion responses.

The role of interstimulus interval and "Stimulus-type" in prepotent response inhibition abilities in people with ASD: A quantitative and qualitative review.

PubMed

Kuiper, Marieke W M; Verhoeven, Elisabeth W M; Geurts, Hilde M

2016-11-01

Autism spectrum disorders (ASD) are associated with prepotent response inhibition difficulties. However, the large variation between studies suggests that understudied factors, such as interstimulus interval (ISI) and "stimulus-type" (both hypothesized proxies of stressors influencing arousal), might influence the inhibitory abilities of people with ASD. Using meta-analysis, we tested whether differences in prepotent response inhibition between people with and without ASD was influenced by ISI. There was not enough variation in "stimulus-type" between the studies to include it as a moderator. Thirty-seven studies met inclusion criteria, with a combined sample size of 950 people with ASD and 966 typically developing controls. Additionally, a qualitative review including studies comparing a neutral and an arousing condition in one experiment was performed to examine whether fast ISI or specific arousing stimuli directly influence prepotent response inhibition. The meta-analysis indicated that ISI was not a relevant moderator. The qualitative review showed that ISI and "stimulus-type" had the same effect for both groups. Although all studies regarding ISI indicated that fast ISI worsened performance, different types of stimuli had either a positive or a negative influence. This could suggest that distinctive stimuli might affect arousal differently. While we replicated the inhibition difficulties in people with ASD (g = .51), our results do not show strong ASD-specific effects of ISI or "stimulus-type" on inhibition. Nonetheless, ISI and "stimulus-type" do seem to influence performance. Future research focusing on potential underlying factors (e.g., baseline physiological arousal) is needed to examine why this is the case. Autism Res 2016, 9: 1124-1141. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Motor cortical hyperexcitability in idiopathic scoliosis: could focal dystonia be a subclinical etiological factor?

PubMed Central

Tormos, José María; Barrios, Carlos; Pascual-Leone, Alvaro

2009-01-01

The aetiology of idiopathic scoliosis (IS) remains unknown; however, there is a growing body of evidence suggesting that the spine deformity could be the expression of a subclinical nervous system disorder. A defective sensory input or an anomalous sensorimotor integration may lead to an abnormal postural tone and therefore the development of a spine deformity. Inhibition of the motor cortico-cortical excitability is abnormal in dystonia. Therefore, the study of cortico-cortical inhibition may shed some insight into the dystonia hypothesis regarding the pathophysiology of IS. Paired pulse transcranial magnetic stimulation was used to study cortico-cortical inhibition and facilitation in nine adolescents with IS, five teenagers with congenital scoliosis (CS) and eight healthy age-matched controls. The effect of a previous conditioning stimulus (80% intensity of resting motor threshold) on the amplitude of the motor-evoked potential induced by the test stimulus (120% of resting motor threshold) was examined at various interstimulus intervals (ISIs) in both abductor pollicis brevis muscles. The results of healthy adolescents and those with CS showed a marked inhibitory effect of the conditioning stimulus on the response to the test stimulus at interstimulus intervals shorter than 6 ms. These findings do not differ from those reported for normal adults. However, children with IS revealed an abnormally reduced cortico-cortical inhibition at the short ISIs. Cortico-cortical inhibition was practically normal on the side of the scoliotic convexity while it was significantly reduced on the side of the scoliotic concavity. In conclusion, these findings support the hypothesis that a dystonic dysfunction underlies in IS. Asymmetrical cortical hyperexcitability may play an important role in the pathogenesis of IS and represents an objective neurophysiological finding that could be used clinically. PMID:20033462

Dissociable effects of inter-stimulus interval and presentation duration on rapid face categorization.

PubMed

Retter, Talia L; Jiang, Fang; Webster, Michael A; Rossion, Bruno

2018-04-01

Fast periodic visual stimulation combined with electroencephalography (FPVS-EEG) has unique sensitivity and objectivity in measuring rapid visual categorization processes. It constrains image processing time by presenting stimuli rapidly through brief stimulus presentation durations and short inter-stimulus intervals. However, the selective impact of these temporal parameters on visual categorization is largely unknown. Here, we presented natural images of objects at a rate of 10 or 20 per second (10 or 20 Hz), with faces appearing once per second (1 Hz), leading to two distinct frequency-tagged EEG responses. Twelve observers were tested with three squarewave image presentation conditions: 1) with an ISI, a traditional 50% duty cycle at 10 Hz (50-ms stimulus duration separated by a 50-ms ISI); 2) removing the ISI and matching the rate, a 100% duty cycle at 10 Hz (100-ms duration with 0-ms ISI); 3) removing the ISI and matching the stimulus presentation duration, a 100% duty cycle at 20 Hz (50-ms duration with 0-ms ISI). The face categorization response was significantly decreased in the 20 Hz 100% condition. The conditions at 10 Hz showed similar face-categorization responses, peaking maximally over the right occipito-temporal (ROT) cortex. However, the onset of the 10 Hz 100% response was delayed by about 20 ms over the ROT region relative to the 10 Hz 50% condition, likely due to immediate forward-masking by preceding images. Taken together, these results help to interpret how the FPVS-EEG paradigm sets temporal constraints on visual image categorization. Copyright © 2018 Elsevier Ltd. All rights reserved.

Characteristics of temporal summation of second pain sensations elicited by brief contact of glabrous skin by a preheated thermode.

PubMed

Vierck, C J; Cannon, R L; Fry, G; Maixner, W; Whitsel, B L

1997-08-01

Temporal summation of sensory intensity was investigated in normal subjects using novel methods of thermal stimulation. A Peltier thermode was heated and then applied in a series of brief (700 ms) contacts to different sites on the glabrous skin of either hand. Repetitive contacts on the thenar or hypothenar eminence, at interstimulus intervals (ISIs) of 3 s, progressively increased the perceived intensity of a thermal sensation that followed each contact at an onset latency > 2 s. Temporal summation of these delayed (late) sensations was proportional to thermode temperature over a range of 45-53 degrees C, progressing from a nonpainful level (warmth) to painful sensations that could be rated as very strong after 10 contacts. Short-latency pain sensations rarely were evoked by such stimuli and never attained levels substantially above pain threshold for the sequences and temperatures presented. Temporal summation produced by brief contacts was greater in rate and amount than increases in sensory intensity resulting from repetitive ramping to the same temperature by a thermode in constant contact with the skin. Variation of the interval between contacts revealed a dependence of sensory intensity on interstimulus interval that is similar to physiological demonstrations of windup, where increasing frequencies of spike train activity are evoked from spinal neurons by repetitive activation of unmyelinated nociceptors. However, substantial summation at repetition rates of > or = 0.33 Hz was observed for temperatures that produced only late sensations of warmth when presented at frequencies < 0.16 Hz. Measurements of subepidermal skin temperature from anesthetized monkeys revealed different time courses for storage and dissipation of heat by the skin than for temporal summation and decay of sensory intensity for the human subjects. For example, negligible heat loss occurred during a 6-s interval between two trials of 10 contacts at 0.33 Hz, but ratings of sensory magnitude decreased from very strong levels of pain to sensations of warmth during the same interval. Evidence that temporal summation of sensory intensity during series of brief contacts relies on central integration, rather than a sensitization of peripheral receptors, was obtained using two approaches. In the first, a moderate degree of temporal summation was observed during alternating stimulation of adjacent but nonoverlapping skin sites at 0.33 Hz. Second, temporal summation was significantly attenuated by prior administration of dextromethorphan, a N-methyl-D-aspartate receptor antagonist.

Evaluation of selected auditory tests in school-age children suspected of auditory processing disorders.

PubMed

Vanniasegaram, Iyngaram; Cohen, Mazal; Rosen, Stuart

2004-12-01

To compare the auditory function of normal-hearing children attending mainstream schools who were referred for an auditory evaluation because of listening/hearing problems (suspected auditory processing disorders [susAPD]) with that of normal-hearing control children. Sixty-five children with a normal standard audiometric evaluation, ages 6-14 yr (32 of whom were referred for susAPD, with the rest age-matched control children), completed a battery of four auditory tests: a dichotic test of competing sentences; a simple discrimination of short tone pairs differing in fundamental frequency at varying interstimulus intervals (TDT); a discrimination task using consonant cluster minimal pairs of real words (CCMP), and an adaptive threshold task for detecting a brief tone presented either simultaneously with a masker (simultaneous masking) or immediately preceding it (backward masking). Regression analyses, including age as a covariate, were performed to determine the extent to which the performance of the two groups differed on each task. Age-corrected z-scores were calculated to evaluate the effectiveness of the complete battery in discriminating the groups. The performance of the susAPD group was significantly poorer than the control group on all but the masking tasks, which failed to differentiate the two groups. The CCMP discriminated the groups most effectively, as it yielded the lowest number of control children with abnormal scores, and performance in both groups was independent of age. By contrast, the proportion of control children who performed poorly on the competing sentences test was unacceptably high. Together, the CCMP (verbal) and TDT (nonverbal) tasks detected impaired listening skills in 56% of the children who were referred to the clinic, compared with 6% of the control children. Performance on the two tasks was not correlated. Two of the four tests evaluated, the CCMP and TDT, proved effective in differentiating the two groups of children of this study. The application of both tests increased the proportion of susAPD children who performed poorly compared with the application of each test alone, while reducing the proportion of control subjects who performed poorly. The findings highlight the importance of carrying out a complete auditory evaluation in children referred for medical attention, even if their standard audiometric evaluation is unremarkable.

Subliminal words durably affect neuronal activity.

PubMed

Gaillard, Raphaël; Cohen, Laurent; Adam, Claude; Clemenceau, Stéphane; Hasboun, Dominique; Baulac, Michel; Willer, Jean-Claude; Dehaene, Stanislas; Naccache, Lionel

2007-10-08

Unconscious mental representations elicited by subliminal stimuli are marked by their fleeting lifetimes, usually below 1 s. Can such evanescent subliminal stimuli, nevertheless, lead to long-lasting learning? To date, evidence suggesting a long-term influence of briefly perceived stimuli on behaviour or brain activity is scarce and questionable. In this study, we used intracranial recordings to provide the first direct demonstration that unconsciously perceived subliminal words could exert long-lasting effects on neuronal signals. When repeating subliminal words over long interstimulus intervals, we observed electrophysiological repetition effects. These unconscious repetition effects suggest that the single presentation of a masked word can durably affect neural architecture.

Writing and overwriting short-term memory

PubMed Central

Killeen, Peter R.

2008-01-01

An integrative account of short-term memory is based on data from pigeons trained to report the majority color in a sequence of lights. Performance showed strong recency effects, was invariant over changes in the interstimulus interval, and improved with increases in the intertrial interval. A compound model of binomial variance around geometrically decreasing memory described the data; a logit transformation rendered it isomorphic with other memory models. The model was generalized for variance in the parameters, where it was shown that averaging exponential and power functions from individuals or items with different decay rates generates new functions that are hyperbolic in time and in log time, respectively. The compound model provides a unified treatment of both the accrual and the dissipation of memory and is consistent with data from various experiments, including the choose-short bias in delayed recall, multielement stimuli, and Rubin and Wenzel’s (1996) meta-analyses of forgetting. PMID:11340865

Effects of physiological aging on mismatch negativity: a meta-analysis.

PubMed

Cheng, Chia-Hsiung; Hsu, Wan-Yu; Lin, Yung-Yang

2013-11-01

Mismatch negativity (MMN) is a promising window on how the functional integrity of auditory sensory memory and change discrimination is modulated by age and relevant clinical conditions. However, the effects of aging on MMN have remained somewhat elusive, particularly at short interstimulus intervals (ISIs). We performed a meta-analysis of peer-reviewed MMN studies that had targeted both young and elderly adults to estimate the mean effect size. Nine studies, consisting of 29 individual investigations, were included and the final total study population consisted of 182 young and 165 elderly subjects. The effects of different deviant types and duration of ISIs on the effect size were assessed. The overall mean effect size was 0.63 (95% CI at 0.43-0.82). The effect sizes for long ISI (>2s, effect size 0.68, 95% CI at 0.31-1.06) and short ISI (<2s, effect size 0.61, 95% CI at 0.39-0.84) were both considered moderate. A further analysis showed a prominent aging-related decrease in MMN responses to duration and frequency changes at short ISIs. It was also interesting to note that the effect size was about 25% larger for duration deviant condition compared to the frequency deviant condition. In conclusion, a reduced MMN response to duration and frequency deviants is a robust feature among the aged adults, which suggests that there has been a decline in the functional integrity of central auditory processing in this population. © 2013.

Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin.

PubMed

Todd, N P M; Govender, S; Colebatch, J G

2016-11-01

Todd et al. (2014ab) have recently demonstrated the presence of vestibular-dependent contributions to auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs), including a particular deflection labeled as an N42/P52 prior to the long-latency AEPs N1 and P2. In this paper we report the results of an experiment to determine the effect of inter-stimulus interval (ISI) and regularity on potentials recorded above and below VEMP threshold. Five healthy, right-handed subjects were recruited and evoked potentials were recorded to binaurally presented sound stimulation, above and below vestibular threshold, at seven stimulus rates with ISIs of 212, 300, 424, 600, 848, 1200 and 1696 ms. The inner five intervals, i.e. 300, 424, 600, 848, 1200 ms, were presented twice in both regular and irregular conditions. ANOVA on the global field power (GFP) were conducted for each of four waves, N42, P52, N1 and P2 with factors of intensity, ISI and regularity. Both N42 and P52 waves showed significant ANOVA effects of intensity but no other main effects or interactions. In contrast both N1 and P2 showed additional effects of ISI, as well as intensity, and evidence of non-linear interactions between ISI and intensity. A source analysis was carried out consistent with prior work suggesting that when above vestibular threshold, in addition to bilateral superior temporal cortex, ocular, cerebellar and cingulate sources are recruited. Further statistical analysis of the source currents indicated that the origin of the interactions with intensity may be the ISI sensitivity of the vestibular-dependent sources. This in turn may reflect a specific vestibular preference for stimulus rates associated with locomotion, i.e. rates close to 2 Hz, or ISIs close to 500 ms, where saccular afferents show increased gain and the corresponding reflexes are most sensitive. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Speeded Probed Recall Is Affected by Grouping.

PubMed

Morra, Sergio; Epidendio, Valentina

2015-01-01

Most of the evidence from previous studies on speeded probed recall supported primacy-gradient models of serial order representation. Two experiments investigated the effect of grouping on speeded probed recall. Six-word lists, followed by a number between 1 and 6, were presented for speeded recall of the word in the position indicated by the number. Grouping was manipulated through interstimulus intervals. In both experiments, a significant Position × Grouping interaction was found in RT. It is concluded that the results are not consistent with models of order representation only based on a primacy gradient. Possible alternative representations of serial order are also discussed; a case is made for a holistic order representation.

Transcranial electric stimulation for intraoperative motor evoked potential monitoring: dependence of required stimulation current on interstimulus interval value.

PubMed

Joksimovic, Boban; Szelenyi, Andrea; Seifert, Volker; Damjanovic, Aleksandar; Damjanovic, Aleksandra; Rasulic, Lukas

2015-05-01

To evaluate the relationship between stimulus intensity by constant current transcranial electric stimulation and interstimulus interval (ISI) for eliciting muscle motor evoked potentials (MEPs) in three different hand muscles and the tibialis anterior muscles. We tested intraoperatively different monophasic constant current pulses and ISIs in 22 patients with clinically normal motor function. Motor thresholds of contralateral muscle MEPs were determined at 0.5 milliseconds (ms) pulse duration and ISIs of 1, 2, 3, 4, 5, and 10 ms using a train of 2, 3, and 5 monophasic constant current pulses of 62 to 104 mA before craniotomy and after closure of the dura mater. The lowest stimulation threshold to elicit MEPs in the examined muscles was achieved with a train of 5 pulses (ISI: 3 ms) before craniotomy, which was statistically significant compared with 2 pulses (ISI: 3 ms) as well as 3 pulses (ISIs: 3 and 10 ms). An ISI of 3 ms gave the lowest motor thresholds with statistical significance compared with the ISIs of 4 ms (2 pulses) and of 1 ms (3 pulses). All current intensity (mA) and ISI (ms) relationship graphs had a trend of the exponential function as y = a + bx + c ρ (x), where y is intensity (mA) and x is ISI (ms). The minimum of the function was determined for each patient and each muscle. The difference was statistically significant between 3 and 5 pulses before craniotomy and between 3 and 5 pulses and 2 and 5 pulses after closure of the dura mater. In adult neurosurgical patients with a normal motor status, a train of 5 pulses and an ISI of 3 ms provide the lowest motor thresholds. We provided evidence of the dependence of required stimulation current on ISI. Georg Thieme Verlag KG Stuttgart · New York.

Short-term memory in zebrafish (Danio rerio).

PubMed

Jia, Jason; Fernandes, Yohaan; Gerlai, Robert

2014-08-15

Learning and memory represent perhaps the most complex behavioral phenomena. Although their underlying mechanisms have been extensively analyzed, only a fraction of the potential molecular components have been identified. The zebrafish has been proposed as a screening tool with which mechanisms of complex brain functions may be systematically uncovered. However, as a relative newcomer in behavioral neuroscience, the zebrafish has not been well characterized for its cognitive and mnemonic features, thus learning and/or memory screens with adults have not been feasible. Here we study short-term memory of adult zebrafish. We show animated images of conspecifics (the stimulus) to the experimental subject during 1 min intervals on ten occasions separated by different (2, 4, 8 or 16 min long) inter-stimulus intervals (ISI), a between subject experimental design. We quantify the distance of the subject from the image presentation screen during each stimulus presentation interval, during each of the 1-min post-stimulus intervals immediately following the stimulus presentations and during each of the 1-min intervals furthest away from the last stimulus presentation interval and just before the next interval (pre-stimulus interval), respectively. Our results demonstrate significant retention of short-term memory even in the longest ISI group but suggest no acquisition of reference memory. Because in the employed paradigm both stimulus presentation and behavioral response quantification is computer automated, we argue that high-throughput screening for drugs or mutations that alter short-term memory performance of adult zebrafish is now becoming feasible. Copyright © 2014 Elsevier B.V. All rights reserved.

The effects of context and musical training on auditory temporal-interval discrimination.

PubMed

Banai, Karen; Fisher, Shirley; Ganot, Ron

2012-02-01

Non sensory factors such as stimulus context and musical experience are known to influence auditory frequency discrimination, but whether the context effect extends to auditory temporal processing remains unknown. Whether individual experiences such as musical training alter the context effect is also unknown. The goal of the present study was therefore to investigate the effects of stimulus context and musical experience on auditory temporal-interval discrimination. In experiment 1, temporal-interval discrimination was compared between fixed context conditions in which a single base temporal interval was presented repeatedly across all trials and variable context conditions in which one of two base intervals was randomly presented on each trial. Discrimination was significantly better in the fixed than in the variable context conditions. In experiment 2 temporal discrimination thresholds of musicians and non-musicians were compared across 3 conditions: a fixed context condition in which the target interval was presented repeatedly across trials, and two variable context conditions differing in the frequencies used for the tones marking the temporal intervals. Musicians outperformed non-musicians on all 3 conditions, but the effects of context were similar for the two groups. Overall, it appears that, like frequency discrimination, temporal-interval discrimination benefits from having a fixed reference. Musical experience, while improving performance, did not alter the context effect, suggesting that improved discrimination skills among musicians are probably not an outcome of more sensitive contextual facilitation or predictive coding mechanisms. Copyright © 2011 Elsevier B.V. All rights reserved.

Effects of inter-stimulus interval and intensity on the perceived urgency of tactile patterns.

PubMed

White, Timothy L; Krausman, Andrea S

2015-05-01

This research examines the feasibility of coding urgency into tactile patterns. Four tactile patterns were presented at either, 12 or 23.5 dB above mean threshold, with an ISI of either 0 (no interval) or 500 msec. Measures included pattern identification and urgency rating on a scale of 1 (least urgent) to 10 (most urgent). Two studies were conducted, a laboratory study and a field study. In the laboratory study, participants received the tactile patterns while seated in front of a computer. For the field study, participants performed dismounted Soldier maneuvers while receiving the tactile patterns. Higher identification rates were found for the 23.5 dB intensity. Patterns presented at the 23.5 dB intensity and no ISI were rated most urgent. No differences in urgency ratings were found for 12 dB based on ISI. Findings support the notion of coding urgency into tactile patterns as a way of augmenting tactile communication. Published by Elsevier Ltd.

Jitter Reduces Response-Time Variability in ADHD: An Ex-Gaussian Analysis.

PubMed

Lee, Ryan W Y; Jacobson, Lisa A; Pritchard, Alison E; Ryan, Matthew S; Yu, Qilu; Denckla, Martha B; Mostofsky, Stewart; Mahone, E Mark

2015-09-01

"Jitter" involves randomization of intervals between stimulus events. Compared with controls, individuals with ADHD demonstrate greater intrasubject variability (ISV) performing tasks with fixed interstimulus intervals (ISIs). Because Gaussian curves mask the effect of extremely slow or fast response times (RTs), ex-Gaussian approaches have been applied to study ISV. This study applied ex-Gaussian analysis to examine the effects of jitter on RT variability in children with and without ADHD. A total of 75 children, aged 9 to 14 years (44 ADHD, 31 controls), completed a go/no-go test with two conditions: fixed ISI and jittered ISI. ADHD children showed greater variability, driven by elevations in exponential (tau), but not normal (sigma) components of the RT distribution. Jitter decreased tau in ADHD to levels not statistically different than controls, reducing lapses in performance characteristic of impaired response control. Jitter may provide a nonpharmacologic mechanism to facilitate readiness to respond and reduce lapses from sustained (controlled) performance. © 2012 SAGE Publications.

Time perception, attention, and memory: a selective review.

PubMed

Block, Richard A; Gruber, Ronald P

2014-06-01

This article provides a selective review of time perception research, mainly focusing on the authors' research. Aspects of psychological time include simultaneity, successiveness, temporal order, and duration judgments. In contrast to findings at interstimulus intervals or durations less than 3.0-5.0 s, there is little evidence for an "across-senses" effect of perceptual modality (visual vs. auditory) at longer intervals or durations. In addition, the flow of time (events) is a pervasive perceptual illusion, and we review evidence on that. Some temporal information is encoded All rights reserved. relatively automatically into memory: People can judge time-related attributes such as recency, frequency, temporal order, and duration of events. Duration judgments in prospective and retrospective paradigms reveal differences between them, as well as variables that moderate the processes involved. An attentional-gate model is needed to account for prospective judgments, and a contextual-change model is needed to account for retrospective judgments. Copyright © 2013 Elsevier B.V. All rights reserved.

Articulatory rehearsal is more than refreshing memory traces.

PubMed

Nishiyama, Ryoji; Ukita, Jun

2013-01-01

This study examined whether additional articulatory rehearsal induced temporary durability of phonological representations, using a 10-s delayed nonword free recall task. Three experiments demonstrated that cumulative rehearsal between the offset of the last study item and the start of the filled delay (Experiments 1 and 3) and a fixed rehearsal of the immediate item during the subsequent interstimulus interval (Experiments 2 and 3) improved free recall performance. These results suggest that an additional rehearsal helps to stabilize phonological representations for a short period. Furthermore, the analyses of serial position curves suggested that the frequency of the articulation affected the durability of the phonological representation. The significance of these findings as clues of the mechanism maintaining verbal information (i.e., verbal working memory) is discussed.

Perception of Scenes in Different Sensory Modalities: A Result of Modal Completion.

PubMed

Gruber, Ronald R; Block, Richard A

2017-01-01

Dynamic perception includes amodal and modal completion, along with apparent movement. It fills temporal gaps for single objects. In 2 experiments, using 6 stimulus presentation conditions involving 3 sensory modalities, participants experienced 8-10 sequential stimuli (200 ms each) with interstimulus intervals (ISIs) of 0.25-7.0 s. Experiments focused on spatiotemporal completion (walking), featural completion (object changing), auditory, completion (falling bomb), and haptic changes (insect crawling). After each trial, participants judged whether they experienced the process of "happening " or whether they simply knew that the process must have occurred. The phenomenon was frequency independent, being reported at short ISIs but not at long ISIs. The phenomenon involves dynamic modal completion and possibly also conceptual processes.

Attention Modulates Spatio-temporal Grouping

PubMed Central

Aydın, Murat; Herzog, Michael H.; Öğmen, Haluk

2011-01-01

Dynamic stimuli are ubiquitous in natural viewing conditions implying that grouping operations need to operate, not only in space, but also jointly in space and time. Moreover, in natural viewing, attention plays an important role in controlling how resources are allocated. We investigated how attention interacts with spatiotemporal perceptual grouping by using a bistable stimulus, called the Ternus-Pikler display. Ternus-Pikler displays can give rise to two different motion percepts, called Element Motion (EM) and Group Motion (GM), the former dominating at short Inter-Stimulus Intervals (ISIs) and the latter at long ISIs. Our results indicate that GM grouping requires more attentional resources than EM grouping. Different theoretical accounts of perceptual grouping and attention are discussed and evaluated in the light of the current results. PMID:21266181

The effects of morphine on fixed-interval patterning and temporal discrimination.

PubMed Central

Odum, A L; Schaal, D W

2000-01-01

Changes produced by drugs in response patterns under fixed-interval schedules of reinforcement have been interpreted to result from changes in temporal discrimination. To examine this possibility, this experiment determined the effects of morphine on the response patterning of 4 pigeons during a fixed-interval 1-min schedule of food delivery with interpolated temporal discrimination trials. Twenty of the 50 total intervals were interrupted by choice trials. Pecks to one key color produced food if the interval was interrupted after a short time (after 2 or 4.64 s). Pecks to another key color produced food if the interval was interrupted after a long time (after 24.99 or 58 s). Morphine (1.0 to 10.0 mg/kg) decreased the index of curvature (a measure of response patterning) during fixed intervals and accuracy during temporal discrimination trials. Accuracy was equally disrupted following short and long sample durations. Although morphine disrupted temporal discrimination in the context of a fixed-interval schedule, these effects are inconsistent with interpretations of the disruption of response patterning as a selective overestimation of elapsed time. The effects of morphine may be related to the effects of more conventional external stimuli on response patterning. PMID:11029024

Intertrial-interval effects on sensitivity (A') and response bias (B") in a temporal discrimination by rats.

PubMed Central

Raslear, T G; Shurtleff, D; Simmons, L

1992-01-01

Killeen and Fetterman's (1988) behavioral theory of animal timing predicts that decreases in the rate of reinforcement should produce decreases in the sensitivity (A') of temporal discriminations and a decrease in miss and correct rejection rates (decrease in bias toward "long" responses). Eight rats were trained on a 10- versus 0.1-s temporal discrimination with an intertrial interval of 5 s and were subsequently tested on probe days on the same discrimination with intertrial intervals of 1, 2.5, 5, 10, or 20 s. The rate of reinforcement declined for all animals as intertrial interval increased. Although sensitivity (A') decreased with increasing intertrial interval, all rats showed an increase in bias to make long responses. PMID:1447544

The precedence effect and its buildup and breakdown in ferrets and humans

PubMed Central

Tolnai, Sandra; Litovsky, Ruth Y.; King, Andrew J.

2014-01-01

Although many studies have examined the precedence effect (PE), few have tested whether it shows a buildup and breakdown in nonhuman animals comparable to that seen in humans. These processes are thought to reflect the ability of the auditory system to adjust to a listener's acoustic environment, and their mechanisms are still poorly understood. In this study, ferrets were trained on a two-alternative forced-choice task to discriminate the azimuthal direction of brief sounds. In one experiment, pairs of noise bursts were presented from two loudspeakers at different interstimulus delays (ISDs). Results showed that localization performance changed as a function of ISD in a manner consistent with the PE being operative. A second experiment investigated buildup and breakdown of the PE by measuring the ability of ferrets to discriminate the direction of a click pair following presentation of a conditioning train. Human listeners were also tested using this paradigm. In both species, performance was better when the test clicks and conditioning train had the same ISD but deteriorated following a switch in the direction of the leading and lagging sounds between the conditioning train and test clicks. These results suggest that ferrets, like humans, experience a buildup and breakdown of the PE. PMID:24606278

Oscillatory support for rapid frequency change processing in infants.

PubMed

Musacchia, Gabriella; Choudhury, Naseem A; Ortiz-Mantilla, Silvia; Realpe-Bonilla, Teresa; Roesler, Cynthia P; Benasich, April A

2013-11-01

Rapid auditory processing and auditory change detection abilities are crucial aspects of speech and language development, particularly in the first year of life. Animal models and adult studies suggest that oscillatory synchrony, and in particular low-frequency oscillations play key roles in this process. We hypothesize that infant perception of rapid pitch and timing changes is mediated, at least in part, by oscillatory mechanisms. Using event-related potentials (ERPs), source localization and time-frequency analysis of event-related oscillations (EROs), we examined the neural substrates of rapid auditory processing in 4-month-olds. During a standard oddball paradigm, infants listened to tone pairs with invariant standard (STD, 800-800 Hz) and variant deviant (DEV, 800-1200 Hz) pitch. STD and DEV tone pairs were first presented in a block with a short inter-stimulus interval (ISI) (Rapid Rate: 70 ms ISI), followed by a block of stimuli with a longer ISI (Control Rate: 300 ms ISI). Results showed greater ERP peak amplitude in response to the DEV tone in both conditions and later and larger peaks during Rapid Rate presentation, compared to the Control condition. Sources of neural activity, localized to right and left auditory regions, showed larger and faster activation in the right hemisphere for both rate conditions. Time-frequency analysis of the source activity revealed clusters of theta band enhancement to the DEV tone in right auditory cortex for both conditions. Left auditory activity was enhanced only during Rapid Rate presentation. These data suggest that local low-frequency oscillatory synchrony underlies rapid processing and can robustly index auditory perception in young infants. Furthermore, left hemisphere recruitment during rapid frequency change discrimination suggests a difference in the spectral and temporal resolution of right and left hemispheres at a very young age. © 2013 Elsevier Ltd. All rights reserved.

Language performance and auditory evoked fields in 2- to 5-year-old children.

PubMed

Yoshimura, Yuko; Kikuchi, Mitsuru; Shitamichi, Kiyomi; Ueno, Sanae; Remijn, Gerard B; Haruta, Yasuhiro; Oi, Manabu; Munesue, Toshio; Tsubokawa, Tsunehisa; Higashida, Haruhiro; Minabe, Yoshio

2012-02-01

Language development progresses at a dramatic rate in preschool children. As rapid temporal processing of speech signals is important in daily colloquial environments, we performed magnetoencephalography (MEG) to investigate the linkage between speech-evoked responses during rapid-rate stimulus presentation (interstimulus interval < 1 s) and language performance in 2- to 5-year-old children (n = 59). Our results indicated that syllables with this short stimulus interval evoked detectable P50m, but not N100m, in most participants, indicating a marked influence of longer neuronal refractory period for stimulation. The results of equivalent dipole estimation showed that the intensity of the P50m component in the left hemisphere was positively correlated with language performance (conceptual inference ability). The observed positive correlations were suggested to reflect the maturation of synaptic organisation or axonal maturation and myelination underlying the acquisition of linguistic abilities. The present study is among the first to use MEG to study brain maturation pertaining to language abilities in preschool children. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Effect of inter-train interval on the induction of repetition suppression of motor-evoked potentials using transcranial magnetic stimulation.

PubMed

Pitkänen, Minna; Kallioniemi, Elisa; Julkunen, Petro

2017-01-01

Repetition suppression (RS) is evident as a weakened response to repeated stimuli after the initial response. RS has been demonstrated in motor-evoked potentials (MEPs) induced with transcranial magnetic stimulation (TMS). Here, we investigated the effect of inter-train interval (ITI) on the induction of RS of MEPs with the attempt to optimize the investigative protocols. Trains of TMS pulses, targeted to the primary motor cortex by neuronavigation, were applied at a stimulation intensity of 120% of the resting motor threshold. The stimulus trains included either four or twenty pulses with an inter-stimulus interval (ISI) of 1 s. The ITI was here defined as the interval between the last pulse in a train and the first pulse in the next train; the ITIs used here were 1, 3, 4, 6, 7, 12, and 17 s. RS was observed with all ITIs except with the ITI of 1 s, in which the ITI was equal to ISI. RS was more pronounced with longer ITIs. Shorter ITIs may not allow sufficient time for a return to baseline. RS may reflect a startle-like response to the first pulse of a train followed by habituation. Longer ITIs may allow more recovery time and in turn demonstrate greater RS. Our results indicate that RS can be studied with confidence at relatively short ITIs of 6 s and above.

Lateral masking in cycling displays: the relative importance of separation, flanker duration, and interstimulus interval for object-mediated updating.

PubMed

Hein, Elisabeth; Moore, Cathleen M

2010-01-01

A central bar repeatedly presented in alternation with two flanking bars can lead to the disappearance of the central bar. Recently it has been suggested that this masking effect could be explained by object-mediated updating: the information from the central bar is integrated into the representation of the flankers, leading not only to the disappearance of the central bar as a separate object, but also to the perception of the flankers in apparent motion between their real position and the position of the central bar. This account suggests that the visibility of the central bar should depend on the same factors as those that influence the construction and maintenance of object representations. Therefore separation between central bar and flankers should not influence visibility as long as the time interval between them is adequate to make an interpretation of the scene in terms of one object moving from one location to the other possible location. We found that if the time interval between the central bar and the flankers is neither too short nor too long, the central bar becomes invisible even at large separations. These findings are inconsistent with traditional accounts of the cycling lateral masking displays in terms of local inhibitory mechanisms.

Selective attention and the auditory vertex potential. 2: Effects of signal intensity and masking noise

NASA Technical Reports Server (NTRS)

Schwent, V. L.; Hillyard, S. A.; Galambos, R.

1975-01-01

A randomized sequence of tone bursts was delivered to subjects at short inter-stimulus intervals with the tones originating from one of three spatially and frequency specific channels. The subject's task was to count the tones in one of the three channels at a time, ignoring the other two, and press a button after each tenth tone. In different conditions, tones were given at high and low intensities and with or without a background white noise to mask the tones. The N sub 1 component of the auditory vertex potential was found to be larger in response to attended channel tones in relation to unattended tones. This selective enhancement of N sub 1 was minimal for loud tones presented without noise and increased markedly for the lower tone intensity and in noise added conditions.

Auditory attentional capture during serial recall: violations at encoding of an algorithm-based neural model?

PubMed

Hughes, Robert W; Vachon, François; Jones, Dylan M

2005-07-01

A novel attentional capture effect is reported in which visual-verbal serial recall was disrupted if a single deviation in the interstimulus interval occurred within otherwise regularly presented task-irrelevant spoken items. The degree of disruption was the same whether the temporal deviant was embedded in a sequence made up of a repeating item or a sequence of changing items. Moreover, the effect was evident during the presentation of the to-be-remembered sequence but not during rehearsal just prior to recall, suggesting that the encoding of sequences is particularly susceptible. The results suggest that attentional capture is due to a violation of an algorithm rather than an aggregate-based neural model and further undermine an attentional capture-based account of the classical changing-state irrelevant sound effect. ((c) 2005 APA, all rights reserved).

Classic conditioning in aged rabbits: delay, trace, and long-delay conditioning.

PubMed

Solomon, P R; Groccia-Ellison, M E

1996-06-01

Young (0.5 years) and aged (2+, 3+, and 4+ years) rabbits underwent acquisition of the classically conditioned nictitating membrane response in a delay (500-ms conditioned stimulus [CS], 400-ms interstimulus interval [ISI]), long-delay (1,000-ms CS, 900-ms ISI), or trace (500-ms CS, 400-ms stimulus-free period) paradigm. Collapsing across age groups, there is a general tendency for animals to acquire trace conditioning more slowly than delay conditioning. Collapsing across conditioning paradigms, there is a general tendency for aged animals to acquire more slowly than younger animals. Of greater significance, however, are the age differences in the different conditioning paradigms. In the delay and long-delay paradigms, significant conditioning deficits first appeared in the 4(+)-year-old group. In the trace conditioning paradigm, significant conditioning deficits became apparent in the 2(+)-year-old animals.

Differential Effects of the Cannabinoid Agonist WIN55,212-2 on Delay and Trace Eyeblink Conditioning

PubMed Central

Steinmetz, Adam B.; Freeman, John H.

2014-01-01

Central cannabinoid-1 receptors (CB1R) play a role in the acquisition of delay eyeblink conditioning but not trace eyeblink conditioning in humans and animals. However, it is not clear why trace conditioning is immune to the effects of cannabinoid receptor compounds. The current study examined the effects of variants of delay and trace conditioning procedures to elucidate the factors that determine the effects of CB1R agonists on eyeblink conditioning. In Experiment 1 rats were administered the cannabinoid agonist WIN55,212-2 during delay, long delay, or trace conditioning. Rats were impaired during delay and long delay but not trace conditioning; the impairment was greater for long delay than delay conditioning. Trace conditioning was further examined in Experiment 2 by manipulating the trace interval and keeping constant the conditioned stimulus (CS) duration. It was found that when the trace interval was 300 ms or less WIN55,212-2 administration impaired the rate of learning. Experiment 3 tested whether the trace interval duration or the relative durations of the CS and trace interval were critical parameters influencing the effects of WIN55,212-2 on eyeblink conditioning. Rats were not impaired with a 100 ms CS, 200 ms trace paradigm but were impaired with a 1000 ms CS, 500 ms trace paradigm, indicating that the duration of the trace interval does not matter but the proportion of the interstimulus interval occupied by the CS relative to the trace period is critical. Taken together the results indicate that cannabinoid agonists affect cerebellar learning the CS is longer than the trace interval. PMID:24128358

Context-Dependent Duration Signals in the Primate Prefrontal Cortex

PubMed Central

Genovesio, Aldo; Seitz, Lucia K.; Tsujimoto, Satoshi; Wise, Steven P.

2016-01-01

The activity of some prefrontal (PF) cortex neurons distinguishes short from long time intervals. Here, we examined whether this property reflected a general timing mechanism or one dependent on behavioral context. In one task, monkeys discriminated the relative duration of 2 stimuli; in the other, they discriminated the relative distance of 2 stimuli from a fixed reference point. Both tasks had a pre-cue period (interval 1) and a delay period (interval 2) with no discriminant stimulus. Interval 1 elapsed before the presentation of the first discriminant stimulus, and interval 2 began after that stimulus. Both intervals had durations of either 400 or 800 ms. Most PF neurons distinguished short from long durations in one task or interval, but not in the others. When neurons did signal something about duration for both intervals, they did so in an uncorrelated or weakly correlated manner. These results demonstrate a high degree of context dependency in PF time processing. The PF, therefore, does not appear to signal durations abstractedly, as would be expected of a general temporal encoder, but instead does so in a highly context-dependent manner, both within and between tasks. PMID:26209845

Selective suppression of the incorrect response implementation in choice behavior assessed by transcranial magnetic stimulation.

PubMed

Tandonnet, Christophe; Garry, Michael I; Summers, Jeffery J

2011-04-01

Selecting the adequate alternative in choice situations may involve an inhibition process. Here we assessed response implementation during the reaction time of a between-hand choice task with single- or paired-pulse (3 or 15 ms interstimulus intervals [ISIs]) transcranial magnetic stimulation of the motor cortex. The amplitude of the single-pulse motor evoked potential (MEP) initially increased for both hands. At around 130 ms, the single-pulse MEP kept increasing for the responding hand and decreased for the nonresponding hand. The paired-pulse MEP revealed a similar pattern for both ISIs with no effect on short intracortical inhibition and intracortical facilitation measures. The results suggest that the incorrect response implementation was selectively suppressed before execution of the correct response, preventing errors in choice context. The results favor models assuming that decision making involves an inhibition process. Copyright © 2010 Society for Psychophysiological Research.

Accessing long-term memory representations during visual change detection.

PubMed

Beck, Melissa R; van Lamsweerde, Amanda E

2011-04-01

In visual change detection tasks, providing a cue to the change location concurrent with the test image (post-cue) can improve performance, suggesting that, without a cue, not all encoded representations are automatically accessed. Our studies examined the possibility that post-cues can encourage the retrieval of representations stored in long-term memory (LTM). Participants detected changes in images composed of familiar objects. Performance was better when the cue directed attention to the post-change object. Supporting the role of LTM in the cue effect, the effect was similar regardless of whether the cue was presented during the inter-stimulus interval, concurrent with the onset of the test image, or after the onset of the test image. Furthermore, the post-cue effect and LTM performance were similarly influenced by encoding time. These findings demonstrate that monitoring the visual world for changes does not automatically engage LTM retrieval.

The emotional memory effect: differential processing or item distinctiveness?

PubMed

Schmidt, Stephen R; Saari, Bonnie

2007-12-01

A color-naming task was followed by incidental free recall to investigate how emotional words affect attention and memory. We compared taboo, nonthreatening negative-affect, and neutral words across three experiments. As compared with neutral words, taboo words led to longer color-naming times and better memory in both within- and between-subjects designs. Color naming of negative-emotion nontaboo words was slower than color naming of neutral words only during block presentation and at relatively short interstimulus intervals (ISIs). The nontaboo emotion words were remembered better than neutral words following blocked and random presentation and at both long and short ISIs, but only in mixed-list designs. Our results support multifactor theories of the effects of emotion on attention and memory. As compared with neutral words, threatening stimuli received increased attention, poststimulus elaboration, and benefit from item distinctiveness, whereas nonthreatening emotional stimuli benefited only from increased item distinctiveness.

Development of auditory sensory memory from 2 to 6 years: an MMN study.

PubMed

Glass, Elisabeth; Sachse, Steffi; von Suchodoletz, Waldemar

2008-08-01

Short-term storage of auditory information is thought to be a precondition for cognitive development, and deficits in short-term memory are believed to underlie learning disabilities and specific language disorders. We examined the development of the duration of auditory sensory memory in normally developing children between the ages of 2 and 6 years. To probe the lifetime of auditory sensory memory we elicited the mismatch negativity (MMN), a component of the late auditory evoked potential, with tone stimuli of two different frequencies presented with various interstimulus intervals between 500 and 5,000 ms. Our findings suggest that memory traces for tone characteristics have a duration of 1-2 s in 2- and 3-year-old children, more than 2 s in 4-year-olds and 3-5 s in 6-year-olds. The results provide insights into the maturational processes involved in auditory sensory memory during the sensitive period of cognitive development.

Auditory sensory memory and language abilities in former late talkers: a mismatch negativity study.

PubMed

Grossheinrich, Nicola; Kademann, Stefanie; Bruder, Jennifer; Bartling, Juergen; Von Suchodoletz, Waldemar

2010-09-01

The present study investigated whether (a) a reduced duration of auditory sensory memory is found in late talking children and (b) whether deficits of sensory memory are linked to persistent difficulties in language acquisition. Former late talkers and children without delayed language development were examined at the age of 4 years and 7 months using mismatch negativity (MMN) with interstimulus intervals (ISIs) of 500 ms and 2000 ms. Additionally, short-term memory, language skills, and nonverbal intelligence were assessed. MMN mean amplitude was reduced for the ISI of 2000 ms in former late talking children both with and without persistent language deficits. In summary, our findings suggest that late talkers are characterized by a reduced duration of auditory sensory memory. However, deficits in auditory sensory memory are not sufficient for persistent language difficulties and may be compensated for by some children.

The color-vision approach to emotional space: cortical evoked potential data.

PubMed

Boucsein, W; Schaefer, F; Sokolov, E N; Schröder, C; Furedy, J J

2001-01-01

A framework for accounting for emotional phenomena proposed by Sokolov and Boucsein (2000) employs conceptual dimensions that parallel those of hue, brightness, and saturation in color vision. The approach that employs the concepts of emotional quality. intensity, and saturation has been supported by psychophysical emotional scaling data gathered from a few trained observers. We report cortical evoked potential data obtained during the change between different emotions expressed in schematic faces. Twenty-five subjects (13 male, 12 female) were presented with a positive, a negative, and a neutral computer-generated face with random interstimulus intervals in a within-subjects design, together with four meaningful and four meaningless control stimuli made up from the same elements. Frontal, central, parietal, and temporal ERPs were recorded from each hemisphere. Statistically significant outcomes in the P300 and N200 range support the potential fruitfulness of the proposed color-vision-model-based approach to human emotional space.

The effects of aging on lifetime of auditory sensory memory in humans.

PubMed

Cheng, Chia-Hsiung; Lin, Yung-Yang

2012-02-01

The amplitude change of cortical responses to repeated stimulation with respect to different interstimulus intervals (ISIs) is considered as an index of sensory memory. To determine the effect of aging on lifetime of auditory sensory memory, N100m responses were recorded in young, middle-aged, and elderly healthy volunteers (n=15 for each group). Trains of 5 successive tones were presented with an inter-train interval of 10 s. In separate sessions, the within-train ISIs were 0.5, 1, 2, 4, and 8 s. The amplitude ratio between N100m responses to the first and fifth stimuli (S5/S1 N100m ratio) within each ISI condition was obtained to reflect the recovery cycle profile. The recovery function time constant (τ) was smaller in the elderly (1.06±0.26 s, p<0.001) and middle-aged (1.70±0.25 s, p=0.009) groups compared with the young group (2.77±0.25 s). In conclusion, the present study suggests an aging-related decrease in lifetime of auditory sensory memory. Copyright © 2011 Elsevier B.V. All rights reserved.

Combining Speed Information Across Space

NASA Technical Reports Server (NTRS)

Verghese, Preeti; Stone, Leland S.

1995-01-01

We used speed discrimination tasks to measure the ability of observers to combine speed information from multiple stimuli distributed across space. We compared speed discrimination thresholds in a classical discrimination paradigm to those in an uncertainty/search paradigm. Thresholds were measured using a temporal two-interval forced-choice design. In the discrimination paradigm, the n gratings in each interval all moved at the same speed and observers were asked to choose the interval with the faster gratings. Discrimination thresholds for this paradigm decreased as the number of gratings increased. This decrease was not due to increasing the effective stimulus area as a control experiment that increased the area of a single grating did not show a similar improvement in thresholds. Adding independent speed noise to each of the n gratings caused thresholds to decrease at a rate similar to the original no-noise case, consistent with observers combining an independent sample of speed from each grating in both the added- and no-noise cases. In the search paradigm, observers were asked to choose the interval in which one of the n gratings moved faster. Thresholds in this case increased with the number of gratings, behavior traditionally attributed to an input bottleneck. However, results from the discrimination paradigm showed that the increase was not due to observers' inability to process these gratings. We have also shown that the opposite trends of the data in the two paradigms can be predicted by a decision theory model that combines independent samples of speed information across space. This demonstrates that models typically used in classical detection and discrimination paradigms are also applicable to search paradigms. As our model does not distinguish between samples in space and time, it predicts that discrimination performance should be the same regardless of whether the gratings are presented in two spatial intervals or two temporal intervals. Our last experiment largely confirmed this prediction.

Active versus passive maintenance of visual nonverbal memory.

PubMed

McKeown, Denis; Holt, Jessica; Delvenne, Jean-Francois; Smith, Amy; Griffiths, Benjamin

2014-08-01

Forgetting over the short term has challenged researchers for more than a century, largely because of the difficulty of controlling what goes on within the memory retention interval. But the "recent-negative-probe" procedure offers a valuable paradigm, by examining the influences of (presumably) unattended memoranda from prior trials. Here we used a recent-probe task to investigate forgetting for visual nonverbal short-term memory. The target stimuli (two visually presented abstract shapes) on a trial were followed after a retention interval by a probe, and participants indicated whether the probe matched one of the target items. Proactive interference, and hence memory for old trial probes, was observed, whereby participants were slowed in rejecting a nonmatching probe on the current trial that nevertheless matched a target item on the previous trial (a recent-negative probe). The attraction of the paradigm is that, by uncovering proactive influences of past-trial probe stimuli, it can be argued that active maintenance in memory of those probes is unlikely. In two experiments, we recorded such proactive interference of prior-trial items over a range of interstimulus (ISI) and intertrial (ITI) intervals (between 1 and 6 s, respectively). Consistent with a proposed two-process memory conception (the active-passive memory model, or APM), actively maintained memories on current trials decayed, but passively "maintained," or unattended, visual memories of stimuli on past trials did not.

The effect of the anodal transcranial direct current stimulation over the cerebellum on the motor cortex excitability.

PubMed

Ates, Mehlika Panpalli; Alaydin, Halil Can; Cengiz, Bulent

2018-04-25

This study was designed to investigate whether the cerebellum has an inhibitory effect on motor cortical excitability. Sixteen healthy adults (age range, 25-50 years, five female) participated in the study. Anodal cerebellar transcranial direct current stimulation (a-cTDCS) was used to modulate cerebellar excitability. A-cTDCS was given for 20 min at 1 mA intensity. The automatic threshold tracking method was used to investigate cortical excitability. Resting motor threshold (RMT), short interval intracortical inhibition (SICI), short interval intracortical facilitation (SICF), intracortical facilitation (ICF), and the input output curve (I-O curve) were motor cortical excitability parameters. a-cTDCS caused a reduction in overall SICI and the reduced SICF for interstimulus intervals (ISIs) to 2.4-4.4 ms. a-cTDCS has no effect on ICF, RMT, and the I-O curve. There were no significant changes in any of these cortical excitability parameters after sham cTDCS. Results of the study indicate that a-cTDCS has a dual (both inhibitory and excitatory) effect on motor cortical excitability, rather than a simple inhibitory effect. The cerebellum modulates both the inhibitory and facilitatory activities of motor cortex (M1) and suggest that cerebello-cerebral motor connectivity is more complex than solely inhibitory or facilitatory connections. Copyright © 2018 Elsevier Inc. All rights reserved.

Neural network architecture for form and motion perception (Abstract Only)

NASA Astrophysics Data System (ADS)

Grossberg, Stephen

1991-08-01

Evidence is given for a new neural network theory of biological motion perception, a motion boundary contour system. This theory clarifies why parallel streams V1 yields V2 and V1 yields MT exist for static form and motion form processing among the areas V1, V2, and MT of visual cortex. The motion boundary contour system consists of several parallel copies, such that each copy is activated by a different range of receptive field sizes. Each copy is further subdivided into two hierarchically organized subsystems: a motion oriented contrast (MOC) filter, for preprocessing moving images; and a cooperative-competitive feedback (CC) loop, for generating emergent boundary segmentations of the filtered signals. The present work uses the MOC filter to explain a variety of classical and recent data about short-range and long- range apparent motion percepts that have not yet been explained by alternative models. These data include split motion; reverse-contrast gamma motion; delta motion; visual inertia; group motion in response to a reverse-contrast Ternus display at short interstimulus intervals; speed- up of motion velocity as interflash distance increases or flash duration decreases; dependence of the transition from element motion to group motion on stimulus duration and size; various classical dependencies between flash duration, spatial separation, interstimulus interval, and motion threshold known as Korte''s Laws; and dependence of motion strength on stimulus orientation and spatial frequency. These results supplement earlier explanations by the model of apparent motion data that other models have not explained; a recent proposed solution of the global aperture problem including explanations of motion capture and induced motion; an explanation of how parallel cortical systems for static form perception and motion form perception may develop, including a demonstration that these parallel systems are variations on a common cortical design; an explanation of why the geometries of static form and motion form differ, in particular why opposite orientations differ by 90 degree(s), whereas opposite directions differ by 180 degree(s), and why a cortical stream V1 yields V2 yields MT is needed; and a summary of how the main properties of other motion perception models can be assimilated into different parts of the motion boundary contour system design.

Interpulse interval discrimination within and across channels: comparison of monopolar and tripolar mode of stimulation.

PubMed

Fielden, Claire A; Kluk, Karolina; McKay, Colette M

2014-05-01

Perception of temporal patterns is crucial to speech understanding and music perception in normal hearing, and is fundamental in the design and implementation of processing strategies for cochlear implants. Two experiments described here investigated the effect of stimulation mode (monopolar versus tripolar) on interpulse interval discrimination using single-electrode stimulation (experiment 1) and dual-electrode stimulation (experiment 2). Experiment 1 required participants to discriminate stimuli containing different interpulse intervals and experiment 2 required listeners to discriminate between two dual-electrode stimuli that had the same temporal pattern on each electrode, but differed in inter-electrode timing. The hypotheses were that (i) stimulation mode would affect the ability to distinguish interpulse interval patterns on a single electrode and (ii) the electrode separation range in which subjects were sensitive to inter-electrode timing would be more restricted in tripolar than in monopolar stimulation. Results in nine cochlear implant users showed that mode did not have a significant mean effect on either the ability to discriminate interpulse intervals in single-electrode stimulation or the range of electrode separation in dual-electrode stimulation in which participants were sensitive to inter-electrode timing. In conclusion, tripolar stimulation did not show any advantage in delivering temporal information within or across channels in this group.

Mind the gap: temporal discrimination and dystonia.

PubMed

Sadnicka, A; Daum, C; Cordivari, C; Bhatia, K P; Rothwell, J C; Manohar, S; Edwards, M J

2017-06-01

One of the most widely studied perceptual measures of sensory dysfunction in dystonia is the temporal discrimination threshold (TDT) (the shortest interval at which subjects can perceive that there are two stimuli rather than one). However the elevated thresholds described may be due to a number of potential mechanisms as current paradigms test not only temporal discrimination but also extraneous sensory and decision-making parameters. In this study two paradigms designed to better quantify temporal processing are presented and a decision-making model is used to assess the influence of decision strategy. 22 patients with cervical dystonia and 22 age-matched controls completed two tasks (i) temporal resolution (a randomized, automated version of existing TDT paradigms) and (ii) interval discrimination (rating the length of two consecutive intervals). In the temporal resolution task patients had delayed (P = 0.021) and more variable (P = 0.013) response times but equivalent discrimination thresholds. Modelling these effects suggested this was due to an increased perceptual decision boundary in dystonia with patients requiring greater evidence before committing to decisions (P = 0.020). Patient performance on the interval discrimination task was normal. Our work suggests that previously observed abnormalities in TDT may not be due to a selective sensory deficit of temporal processing as decision-making itself is abnormal in cervical dystonia. © 2017 EAN.

Influence of genetic discrimination perceptions and knowledge on cancer genetics referral practice among clinicians.

PubMed

Lowstuter, Katrina J; Sand, Sharon; Blazer, Kathleen R; MacDonald, Deborah J; Banks, Kimberly C; Lee, Carol A; Schwerin, Barbara U; Juarez, Margaret; Uman, Gwen C; Weitzel, Jeffrey N

2008-09-01

To describe nongenetics clinicians' perceptions and knowledge of cancer genetics and laws prohibiting genetic discrimination, attitudes toward the use of cancer genetic testing, and referral practices. Invitations to participate were sent to a random stratified sample of California Medical Association members and to all members of California Association of Nurse Practitioners and California Latino Medical Association. Responders in active practice were eligible and completed a 47-item survey. There were 1181 qualified participants (62% physicians). Although 96% viewed genetic testing as beneficial for their patients, 75% believed fear of genetic discrimination would cause patients to decline testing. More than 60% were not aware of federal or California laws prohibiting health insurance discrimination--concern about genetic discrimination was selected as a reason for nonreferral by 11%. A positive attitude toward genetic testing was the strongest predictor of referral (odds ratio: 3.55 [95% confidence interval: 2.24-5.63], P < 0.001) in stepwise logistic regression analyses. The higher the belief in genetic discrimination, the less likely a participant was to refer (odds ratio: 0.72 [95% confidence interval: 0.518-0.991], P < 0.05), whereas more knowledge of genetic discrimination law was associated with comfort recommending (odds ratio: 1.18 [95% confidence interval: 1.11-1.25], P < 0.001) and actual referral (odds ratio: 3.55 [95% confidence interval: 2.24-5.63], P < 0.001). Concerns about genetic discrimination and knowledge deficits may be barriers to cancer genetics referrals. Clinician education may help promote access to cancer screening and prevention.

Difference magnitude is not measured by discrimination steps for order of point patterns.

PubMed

Protonotarios, Emmanouil D; Johnston, Alan; Griffin, Lewis D

2016-07-01

We have shown in previous work that the perception of order in point patterns is consistent with an interval scale structure (Protonotarios, Baum, Johnston, Hunter, & Griffin, 2014). The psychophysical scaling method used relies on the confusion between stimuli with similar levels of order, and the resulting discrimination scale is expressed in just-noticeable differences (jnds). As with other perceptual dimensions, an interesting question is whether suprathreshold (perceptual) differences are consistent with distances between stimuli on the discrimination scale. To test that, we collected discrimination data, and data based on comparison of perceptual differences. The stimuli were jittered square lattices of dots, covering the range from total disorder (Poisson) to perfect order (square lattice), roughly equally spaced on the discrimination scale. Observers picked the most ordered pattern from a pair, and the pair of patterns with the greatest difference in order from two pairs. Although the judgments of perceptual difference were found to be consistent with an interval scale, like the discrimination judgments, no common interval scale that could predict both sets of data was possible. In particular, the midpattern of the perceptual scale is 11 jnds away from the ordered end, and 5 jnds from the disordered end of the discrimination scale.

Serum prolactin revisited: parametric reference intervals and cross platform evaluation of polyethylene glycol precipitation-based methods for discrimination between hyperprolactinemia and macroprolactinemia.

PubMed

Overgaard, Martin; Pedersen, Susanne Møller

2017-10-26

Hyperprolactinemia diagnosis and treatment is often compromised by the presence of biologically inactive and clinically irrelevant higher-molecular-weight complexes of prolactin, macroprolactin. The objective of this study was to evaluate the performance of two macroprolactin screening regimes across commonly used automated immunoassay platforms. Parametric total and monomeric gender-specific reference intervals were determined for six immunoassay methods using female (n=96) and male sera (n=127) from healthy donors. The reference intervals were validated using 27 hyperprolactinemic and macroprolactinemic sera, whose presence of monomeric and macroforms of prolactin were determined using gel filtration chromatography (GFC). Normative data for six prolactin assays included the range of values (2.5th-97.5th percentiles). Validation sera (hyperprolactinemic and macroprolactinemic; n=27) showed higher discordant classification [mean=2.8; 95% confidence interval (CI) 1.2-4.4] for the monomer reference interval method compared to the post-polyethylene glycol (PEG) recovery cutoff method (mean=1.8; 95% CI 0.8-2.8). The two monomer/macroprolactin discrimination methods did not differ significantly (p=0.089). Among macroprolactinemic sera evaluated by both discrimination methods, the Cobas and Architect/Kryptor prolactin assays showed the lowest and the highest number of misclassifications, respectively. Current automated immunoassays for prolactin testing require macroprolactin screening methods based on PEG precipitation in order to discriminate truly from falsely elevated serum prolactin. While the recovery cutoff and monomeric reference interval macroprolactin screening methods demonstrate similar discriminative ability, the latter method also provides the clinician with an easy interpretable monomeric prolactin concentration along with a monomeric reference interval.

A role of right middle frontal gyrus in reorienting of attention: a case study

PubMed Central

Japee, Shruti; Holiday, Kelsey; Satyshur, Maureen D.; Mukai, Ikuko; Ungerleider, Leslie G.

2015-01-01

The right middle fontal gyrus (MFG) has been proposed to be a site of convergence of the dorsal and ventral attention networks, by serving as a circuit-breaker to interrupt ongoing endogenous attentional processes in the dorsal network and reorient attention to an exogenous stimulus. Here, we probed the contribution of the right MFG to both endogenous and exogenous attention by comparing performance on an orientation discrimination task of a patient with a right MFG resection and a group of healthy controls. On endogenously cued trials, participants were shown a central cue that predicted with 90% accuracy the location of a subsequent peri-threshold Gabor patch stimulus. On exogenously cued trials, a cue appeared briefly at one of two peripheral locations, followed by a variable inter-stimulus interval (ISI; range 0–700 ms) and a Gabor patch in the same or opposite location as the cue. Behavioral data showed that for endogenous, and short ISI exogenous trials, valid cues facilitated responses compared to invalid cues, for both the patient and controls. However, at long ISIs, the patient exhibited difficulty in reverting to top-down attentional control, once the facilitatory effect of the exogenous cue had dissipated. When explicitly cued during long ISIs to attend to both stimulus locations, the patient was able to engage successfully in top-down control. This result indicates that the right MFG may play an important role in reorienting attention from exogenous to endogenous attentional control. Resting state fMRI data revealed that the right superior parietal lobule and right orbitofrontal cortex, showed significantly higher correlations with a left MFG seed region (a region tightly coupled with the right MFG in controls) in the patient relative to controls. We hypothesize that this paradoxical increase in cortical coupling represents a compensatory mechanism in the patient to offset the loss of function of the resected tissue in right prefrontal cortex. PMID:25784862

Does the experience of discrimination affect health? A cross-sectional study of Korean elders.

PubMed

Chun, Heeran; Kang, Minah; Cho, Sung-il; Jung-Choi, Kyunghee; Jang, Soong-Nang; Khang, Young-Ho

2015-03-01

This study was conducted among 992 Koreans aged 60 to 89 to examine the effects of perceived discrimination on the health of an ethnically homogenous older population. Perceived discrimination was measured with a self-report instrument. Health outcomes included depressive symptoms, poor self-rated health, and chronic diseases. Of the elderly Koreans surveyed, 23.5% reported having experienced discrimination based on education, age, birthplace, birth order, or gender. Among women, 23.1% reported experiencing gender discrimination, compared to 0.9% among men. Men reported education and age discrimination most frequently-9.4% and 7.7%, respectively. Those who reported experiencing any discrimination were 2.19 times more likely to report depressive symptoms (95% confidence interval = 1.50-3.22) and 1.40 times more likely to report poor self-rated health (95% confidence interval = 1.02-1.93). The health effects of educational discrimination appeared most prominent. This study supports the positive associations between perceived discrimination and poorer health, particularly mental health, in later life. © 2013 APJPH.

Local inhibition of GABA affects precedence effect in the inferior colliculus

PubMed Central

Wang, Yanjun; Wang, Ningyu; Wang, Dan; Jia, Jun; Liu, Jinfeng; Xie, Yan; Wen, Xiaohui; Li, Xiaoting

2014-01-01

The precedence effect is a prerequisite for faithful sound localization in a complex auditory environment, and is a physiological phenomenon in which the auditory system selectively suppresses the directional information from echoes. Here we investigated how neurons in the inferior colliculus respond to the paired sounds that produce precedence-effect illusions, and whether their firing behavior can be modulated through inhibition with gamma-aminobutyric acid (GABA). We recorded extracellularly from 36 neurons in rat inferior colliculus under three conditions: no injection, injection with saline, and injection with gamma-aminobutyric acid. The paired sounds that produced precedence effects were two identical 4-ms noise bursts, which were delivered contralaterally or ipsilaterally to the recording site. The normalized neural responses were measured as a function of different inter-stimulus delays and half-maximal interstimulus delays were acquired. Neuronal responses to the lagging sounds were weak when the inter-stimulus delay was short, but increased gradually as the delay was lengthened. Saline injection produced no changes in neural responses, but after local gamma-aminobutyric acid application, responses to the lagging stimulus were suppressed. Application of gamma-aminobutyric acid affected the normalized response to lagging sounds, independently of whether they or the paired sounds were contralateral or ipsilateral to the recording site. These observations suggest that local inhibition by gamma-aminobutyric acid in the rat inferior colliculus shapes the neural responses to lagging sounds, and modulates the precedence effect. PMID:25206830

Experiences of Discrimination and Incident Type 2 Diabetes Mellitus: The Multi-Ethnic Study of Atherosclerosis (MESA).

PubMed

Whitaker, Kara M; Everson-Rose, Susan A; Pankow, James S; Rodriguez, Carlos J; Lewis, Tené T; Kershaw, Kiarri N; Diez Roux, Ana V; Lutsey, Pamela L

2017-08-15

Experiences of discrimination are associated with increased risk of adverse health outcomes; however, it is unknown whether discrimination is related to incident type 2 diabetes mellitus (diabetes). We investigated the associations of major experiences of discrimination (unfair treatment in 6 situations) and everyday discrimination (frequency of day-to-day experiences of unfair treatment) with incident diabetes among 5,310 participants from the Multi-Ethnic Study of Atherosclerosis, enrolled in 2000-2002. Using Cox proportional hazards models, we estimated hazard ratios and confidence intervals, adjusting for demographic factors, depressive symptoms, stress, smoking, alcohol, physical activity, diet, waist circumference, and body mass index. Over a median follow-up of 9.4 years, 654 diabetes cases were accrued. Major experiences of discrimination were associated with greater risk of incident diabetes when modeled continuously (for each additional experience of discrimination, hazard ratio = 1.09, 95% confidence interval: 1.01, 1.17) or categorically (for ≥2 experiences vs. 0, hazard ratio = 1.34, 95% confidence interval: 1.08, 1.66). Similar patterns were observed when evaluating discrimination attributed to race/ethnicity or to a combination of other sources. Everyday discrimination was not associated with incident diabetes. In conclusion, major experiences of discrimination were associated with increased risk of incident diabetes, independent of obesity or behavioral and psychosocial factors. Future research is needed to explore the mechanisms of the discrimination-diabetes relationship. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Both trace and delay conditioned eyeblink responding can be dissociated from outcome expectancy.

PubMed

Weidemann, Gabrielle; Broderick, Joshua; Lovibond, Peter F; Mitchell, Christopher J

2012-01-01

Squire and colleagues have proposed that trace and delay eyeblink conditioning are fundamentally different kinds of learning: trace conditioning requires acquisition of a conscious declarative memory for the stimulus contingencies whereas delay conditioning does not. Declarative memory in trace conditioning is thought to generate conditioned responding through the activation of a conscious expectancy for when the unconditioned stimulus (US) is going to occur. Perruchet (1985) has previously shown that in a 50% partial reinforcement design it is possible to dissociate single cue delay eyeblink conditioning from conscious expectancy for the US by examining performance over runs of reinforced and nonreinforced trials. Clark, Manns, and Squire (2001) claim that this dissociation does not occur in trace eyeblink conditioning. In the present experiment we examined the Perruchet effect for short, moderate, and long trace intervals (600, 1000, and 1400 ms) and for the equivalent interstimulus intervals (ISIs) in a delay conditioning procedure. We found evidence for a dissociation of eyeblink CRs and US expectancy over runs regardless of whether there was a delay or a trace arrangement of cues. The reasons for the Perruchet effect are still unclear, but the present data suggest that it does not depend on a separate nondeclarative system of the type proposed by Squire and colleagues. (c) 2012 APA, all rights reserved.

Influence of double stimulation on sound-localization behavior in barn owls.

PubMed

Kettler, Lutz; Wagner, Hermann

2014-12-01

Barn owls do not immediately approach a source after they hear a sound, but wait for a second sound before they strike. This represents a gain in striking behavior by avoiding responses to random incidents. However, the first stimulus is also expected to change the threshold for perceiving the subsequent second sound, thus possibly introducing some costs. We mimicked this situation in a behavioral double-stimulus paradigm utilizing saccadic head turns of owls. The first stimulus served as an adapter, was presented in frontal space, and did not elicit a head turn. The second stimulus, emitted from a peripheral source, elicited the head turn. The time interval between both stimuli was varied. Data obtained with double stimulation were compared with data collected with a single stimulus from the same positions as the second stimulus in the double-stimulus paradigm. Sound-localization performance was quantified by the response latency, accuracy, and precision of the head turns. Response latency was increased with double stimuli, while accuracy and precision were decreased. The effect depended on the inter-stimulus interval. These results suggest that waiting for a second stimulus may indeed impose costs on sound localization by adaptation and this reduces the gain obtained by waiting for a second stimulus.

Long-term memory of color stimuli in the jungle crow (Corvus macrorhynchos).

PubMed

Bogale, Bezawork Afework; Sugawara, Satoshi; Sakano, Katsuhisa; Tsuda, Sonoko; Sugita, Shoei

2012-03-01

Wild-caught jungle crows (n = 20) were trained to discriminate between color stimuli in a two-alternative discrimination task. Next, crows were tested for long-term memory after 1-, 2-, 3-, 6-, and 10-month retention intervals. This preliminary study showed that jungle crows learn the task and reach a discrimination criterion (80% or more correct choices in two consecutive sessions of ten trials) in a few trials, and some even in a single session. Most, if not all, crows successfully remembered the constantly reinforced visual stimulus during training after all retention intervals. These results suggest that jungle crows have a high retention capacity for learned information, at least after a 10-month retention interval and make no or very few errors. This study is the first to show long-term memory capacity of color stimuli in corvids following a brief training that memory rather than rehearsal was apparent. Memory of visual color information is vital for exploitation of biological resources in crows. We suspect that jungle crows could remember the learned color discrimination task even after a much longer retention interval.

Sensory tricks and brain excitability in cervical dystonia: a transcranial magnetic stimulation study.

PubMed

Amadio, Stefano; Houdayer, Elise; Bianchi, Francesca; Tesfaghebriel Tekle, Habtom; Urban, Ivan Pietro; Butera, Calogera; Guerriero, Roberta; Cursi, Marco; Leocani, Letizia; Comi, Giancarlo; Del Carro, Ubaldo

2014-08-01

Sensory tricks such as touching the face with fingertips often improve cervical dystonia [CD]. This study is to determine whether sensory tricks modulate motor cortex excitability, assessed by paired-pulse transcranial magnetic stimulation [p-pTMS]. Eight patients with rotational CD underwent p-pTMS, at rest and when the sensory trick was applied. To test intracortical inhibition [ICI] and facilitation [ICF], the amplitude ratio between conditioned and unconditioned cortical motor evoked potentials was measured at several interstimulus intervals (ISI 1, 3, 15, and 20 ms) and compared with controls mimicking patients' sensory tricks. At rest, a significant ICF enhancement was found at ISIs 15 through 20 in patients compared with controls, whereas no significant ICI changes were observed. Sensory tricks significantly reduced the abnormal ICF in patients and did not induce any change in controls. In our CD patients, sensory tricks seem to improve dystonia through an inhibitory effect on motor cortex excitability. © 2014 International Parkinson and Movement Disorder Society.

New objects do not capture attention without a sensory transient.

PubMed

Hollingworth, Andrew; Simons, Daniel J; Franconeri, Steven L

2010-07-01

Attention capture occurs when a stimulus event involuntarily recruits attention. The abrupt appearance of a new object is perhaps the most well-studied attention-capturing event, yet there is debate over the root cause of this capture. Does a new object capture attention because it involves the creation of a new object representation or because its appearance creates a characteristic luminance transient? The present study sought to resolve this question by introducing a new object into a search display, either with or without a unique luminance transient. Contrary to the results of a recent study (Davoli, Suszko, & Abrams, 2007), when the new object's transient was masked by a brief interstimulus interval introduced between the placeholder and search arrays, a new object did not capture attention. Moreover, when a new object's transient was masked, participants could not locate a new object efficiently even when that was their explicit goal. Together, these data suggest that luminance transient signals are necessary for attention capture by new objects.

A Novel Stimulus Artifact Removal Technique for High-Rate Electrical Stimulation

PubMed Central

Heffer, Leon F; Fallon, James B

2008-01-01

Electrical stimulus artifact corrupting electrophysiological recordings often make the subsequent analysis of the underlying neural response difficult. This is particularly evident when investigating short-latency neural activity in response to high-rate electrical stimulation. We developed and evaluated an off-line technique for the removal of stimulus artifact from electrophysiological recordings. Pulsatile electrical stimulation was presented at rates of up to 5000 pulses/s during extracellular recordings of guinea pig auditory nerve fibers. Stimulus artifact was removed by replacing the sample points at each stimulus artifact event with values interpolated along a straight line, computed from neighbouring sample points. This technique required only that artifact events be identifiable and that the artifact duration remained less than both the inter-stimulus interval and the time course of the action potential. We have demonstrated that this computationally efficient sample-and-interpolate technique removes the stimulus artifact with minimal distortion of the action potential waveform. We suggest that this technique may have potential applications in a range of electrophysiological recording systems. PMID:18339428

Effects of verbal and nonverbal interference on spatial and object visual working memory.

PubMed

Postle, Bradley R; Desposito, Mark; Corkin, Suzanne

2005-03-01

We tested the hypothesis that a verbal coding mechanism is necessarily engaged by object, but not spatial, visual working memory tasks. We employed a dual-task procedure that paired n-back working memory tasks with domain-specific distractor trials inserted into each interstimulus interval of the n-back tasks. In two experiments, object n-back performance demonstrated greater sensitivity to verbal distraction, whereas spatial n-back performance demonstrated greater sensitivity to motion distraction. Visual object and spatial working memory may differ fundamentally in that the mnemonic representation of featural characteristics of objects incorporates a verbal (perhaps semantic) code, whereas the mnemonic representation of the location of objects does not. Thus, the processes supporting working memory for these two types of information may differ in more ways than those dictated by the "what/where" organization of the visual system, a fact more easily reconciled with a component process than a memory systems account of working memory function.

Subvocal articulatory rehearsal during verbal working memory in multiple sclerosis.

PubMed

Sweet, Lawrence H; Vanderhill, Susan D; Jerskey, Beth A; Gordon, Norman M; Paul, Robert H; Cohen, Ronald A

2010-10-01

This study was designed to examine verbal working memory (VWM) components among multiple sclerosis (MS) patients and determine the influence of information processing speed. Of two frequently studied VWM sub-components, subvocal rehearsal was expected to be more affected by MS than short-term memory buffering. Furthermore, worse subvocal rehearsal was predicted to be specifically related to slower cognitive processing. Fifteen MS patients were administered a neuropsychological battery assessing VWM, processing speed, mood, fatigue, and disability. Participants performed a 2-Back VWM task with modified nested conditions designed to increase subvocal rehearsal (via inter-stimulus interval) and short-term memory buffering demands (via phonological similarity). Performance during these 2-Back conditions did not significantly differ and both exhibited strong positive correlations with disability. However, only scores on the subvocal rehearsal 2-Back were significantly related to performance on the remaining test battery, including processing speed and depressive symptoms. Findings suggest that performance during increased subvocal rehearsal demands is specifically influenced by cognitive processing speed and depressive symptoms.

Reduced cortical inhibition in violent offenders: a study with transcranial magnetic stimulation.

PubMed

Philipp-Wiegmann, Florence; Rösler, Michael; Römer, Konstanze D; Schneider, Marc; Baumgart, Sibylle; Retz, Wolfgang

2011-01-01

Aggression and violent behaviour are often regarded as a threat to society. Therefore, understanding violent behaviour has high social relevance. We performed a study with transcranial magnetic stimulation on a sample of violent offenders in order to measure cortical inhibition in the motor neuron system that is part of the frontal cortex. To investigate intracortical inhibition and intracortical facilitation, we conducted paired-pulse stimulation according to the technique of Kujirai and his group (see Method). The investigation sample comprised 62 right-handers: 32 prisoners who had committed severe violent crimes and 30 controls with no history of violence. All subjects were male and matched for age. Using the paired-pulse paradigm with interstimulus intervals (ISI) of 1-15 ms, a reduced cortical inhibition (ISI: 3 ms) was found in the left cortex of violent offenders compared with control subjects. These findings corroborate the hypothesis of inhibition deficits and frontal cortex dysfunction in violent offenders when compared with non-violent control subjects. Copyright © 2011 S. Karger AG, Basel.

Spaced Learning Enhances Subsequent Recognition Memory by Reducing Neural Repetition Suppression

PubMed Central

Xue, Gui; Mei, Leilei; Chen, Chuansheng; Lu, Zhong-Lin; Poldrack, Russell; Dong, Qi

2012-01-01

Spaced learning usually leads to better recognition memory as compared with massed learning, yet the underlying neural mechanisms remain elusive. One open question is whether the spacing effect is achieved by reducing neural repetition suppression. In this fMRI study, participants were scanned while intentionally memorizing 120 novel faces, half under the massed learning condition (i.e., four consecutive repetitions with jittered interstimulus interval) and the other half under the spaced learning condition (i.e., the four repetitions were interleaved). Recognition memory tests afterward revealed a significant spacing effect: Participants recognized more items learned under the spaced learning condition than under the massed learning condition. Successful face memory encoding was associated with stronger activation in the bilateral fusiform gyrus, which showed a significant repetition suppression effect modulated by subsequent memory status and spaced learning. Specifically, remembered faces showed smaller repetition suppression than forgotten faces under both learning conditions, and spaced learning significantly reduced repetition suppression. These results suggest that spaced learning enhances recognition memory by reducing neural repetition suppression. PMID:20617892

Spaced learning enhances subsequent recognition memory by reducing neural repetition suppression.

PubMed

Xue, Gui; Mei, Leilei; Chen, Chuansheng; Lu, Zhong-Lin; Poldrack, Russell; Dong, Qi

2011-07-01

Spaced learning usually leads to better recognition memory as compared with massed learning, yet the underlying neural mechanisms remain elusive. One open question is whether the spacing effect is achieved by reducing neural repetition suppression. In this fMRI study, participants were scanned while intentionally memorizing 120 novel faces, half under the massed learning condition (i.e., four consecutive repetitions with jittered interstimulus interval) and the other half under the spaced learning condition (i.e., the four repetitions were interleaved). Recognition memory tests afterward revealed a significant spacing effect: Participants recognized more items learned under the spaced learning condition than under the massed learning condition. Successful face memory encoding was associated with stronger activation in the bilateral fusiform gyrus, which showed a significant repetition suppression effect modulated by subsequent memory status and spaced learning. Specifically, remembered faces showed smaller repetition suppression than forgotten faces under both learning conditions, and spaced learning significantly reduced repetition suppression. These results suggest that spaced learning enhances recognition memory by reducing neural repetition suppression.

Effects of verbal and nonverbal interference on spatial and object visual working memory

PubMed Central

POSTLE, BRADLEY R.; D’ESPOSITO, MARK; CORKIN, SUZANNE

2005-01-01

We tested the hypothesis that a verbal coding mechanism is necessarily engaged by object, but not spatial, visual working memory tasks. We employed a dual-task procedure that paired n-back working memory tasks with domain-specific distractor trials inserted into each interstimulus interval of the n-back tasks. In two experiments, object n-back performance demonstrated greater sensitivity to verbal distraction, whereas spatial n-back performance demonstrated greater sensitivity to motion distraction. Visual object and spatial working memory may differ fundamentally in that the mnemonic representation of featural characteristics of objects incorporates a verbal (perhaps semantic) code, whereas the mnemonic representation of the location of objects does not. Thus, the processes supporting working memory for these two types of information may differ in more ways than those dictated by the “what/where” organization of the visual system, a fact more easily reconciled with a component process than a memory systems account of working memory function. PMID:16028575

Does sensitivity in binary choice tasks depend on response modality?

PubMed

Szumska, Izabela; van der Lubbe, Rob H J; Grzeczkowski, Lukasz; Herzog, Michael H

2016-07-01

In most models of vision, a stimulus is processed in a series of dedicated visual areas, leading to categorization of this stimulus, and possible decision, which subsequently may be mapped onto a motor-response. In these models, stimulus processing is thought to be independent of the response modality. However, in theories of event coding, common coding, and sensorimotor contingency, stimuli may be very specifically mapped onto certain motor-responses. Here, we compared performance in a shape localization task and used three different response modalities: manual, saccadic, and verbal. Meta-contrast masking was employed at various inter-stimulus intervals (ISI) to manipulate target visibility. Although we found major differences in reaction times for the three response modalities, accuracy remained at the same level for each response modality (and all ISIs). Our results support the view that stimulus-response (S-R) associations exist only for specific instances, such as reflexes or skills, but not for arbitrary S-R pairings. Copyright © 2016 Elsevier Inc. All rights reserved.

Influence of motion on face recognition.

PubMed

Bonfiglio, Natale S; Manfredi, Valentina; Pessa, Eliano

2012-02-01

The influence of motion information and temporal associations on recognition of non-familiar faces was investigated using two groups which performed a face recognition task. One group was presented with regular temporal sequences of face views designed to produce the impression of motion of the face rotating in depth, the other group with random sequences of the same views. In one condition, participants viewed the sequences of the views in rapid succession with a negligible interstimulus interval (ISI). This condition was characterized by three different presentation times. In another condition, participants were presented a sequence with a 1-sec. ISI among the views. That regular sequences of views with a negligible ISI and a shorter presentation time were hypothesized to give rise to better recognition, related to a stronger impression of face rotation. Analysis of data from 45 participants showed a shorter presentation time was associated with significantly better accuracy on the recognition task; however, differences between performances associated with regular and random sequences were not significant.

Decision making and action implementation: evidence for an early visually triggered motor activation specific to potential actions.

PubMed

Tandonnet, Christophe; Garry, Michael I; Summers, Jeffery J

2013-07-01

To make a decision may rely on accumulating evidence in favor of one alternative until a threshold is reached. Sequential-sampling models differ by the way of accumulating evidence and the link with action implementation. Here, we tested a model's prediction of an early action implementation specific to potential actions. We assessed the dynamics of action implementation in go/no-go and between-hand choice tasks by transcranial magnetic stimulation of the motor cortex (single- or paired-pulse TMS; 3-ms interstimulus interval). Prior to implementation of the selected action, the amplitude of the motor evoked potential first increased whatever the visual stimulus but only for the hand potentially involved in the to-be-produced action. These findings suggest that visual stimuli can trigger an early motor activation specific to potential actions, consistent with race-like models with continuous transmission between decision making and action implementation. Copyright © 2013 Society for Psychophysiological Research.

Retention of sequential drug discriminations under fixed-interval schedules for long time periods without training.

PubMed

Li, Mi; McMillan, Donald E

2003-08-22

The experiments showed that sequential drug discriminations can be learned and retained under a fixed-interval (FI) schedule for more than 18 months without additional training under a complex three-choice procedure. Pigeons were trained to discriminate among 5 mg/kg pentobarbital, 2 mg/kg D-amphetamine, and saline. After responding stabilized, dose-response curves were determined for other drugs. Subsequently, pentobarbital was replaced with 5 mg/kg morphine as a training drug, and D-amphetamine was replaced with 30 mg/kg caffeine. After the pigeons learned these new discriminations, dose-response curves were redetermined. Initially, chlordiazepoxide substituted for pentobarbital, cocaine substituted for D-amphetamine, and nicotine partially substituted for D-amphetamine. Morphine, Delta9-tetrahydrocannabinol, and caffeine did not substitute for either drug. After retraining with morphine and caffeine, responding occurred on the pentobarbital/morphine key after pentobarbital, chlordiazepoxide and morphine and on the D-amphetamine/caffeine key after D-amphetamine, cocaine and caffeine. After nicotine and Delta9-tetrahyrdocannabinol, responding occurred on the saline key. These data show that drug discriminations learned under fixed-interval schedules are retained for long time periods, even when discrimination training with other drugs occurs during the retention period.

The third-stimulus temporal discrimination threshold: focusing on the temporal processing of sensory input within primary somatosensory cortex.

PubMed

Leodori, Giorgio; Formica, Alessandra; Zhu, Xiaoying; Conte, Antonella; Belvisi, Daniele; Cruccu, Giorgio; Hallett, Mark; Berardelli, Alfredo

2017-10-01

The somatosensory temporal discrimination threshold (STDT) has been used in recent years to investigate time processing of sensory information, but little is known about the physiological correlates of somatosensory temporal discrimination. The objective of this study was to investigate whether the time interval required to discriminate between two stimuli varies according to the number of stimuli in the task. We used the third-stimulus temporal discrimination threshold (ThirdDT), defined as the shortest time interval at which an individual distinguishes a third stimulus following a pair of stimuli delivered at the STDT. The STDT and ThirdDT were assessed in 31 healthy subjects. In a subgroup of 10 subjects, we evaluated the effects of the stimuli intensity on the ThirdDT. In a subgroup of 16 subjects, we evaluated the effects of S1 continuous theta-burst stimulation (S1-cTBS) on the STDT and ThirdDT. Results show that ThirdDT is shorter than STDT. We found a positive correlation between STDT and ThirdDT values. As long as the stimulus intensity was within the perceivable and painless range, it did not affect ThirdDT values. S1-cTBS significantly affected both STDT and ThirdDT, although the latter was affected to a greater extent and for a longer period of time. We conclude that the interval needed to discriminate between time-separated tactile stimuli is related to the number of stimuli used in the task. STDT and ThirdDT are encoded in S1, probably by a shared tactile temporal encoding mechanism whose performance rapidly changes during the perception process. ThirdDT is a new method to measure somatosensory temporal discrimination. NEW & NOTEWORTHY To investigate whether the time interval required to discriminate between stimuli varies according to changes in the stimulation pattern, we used the third-stimulus temporal discrimination threshold (ThirdDT). We found that the somatosensory temporal discrimination acuity varies according to the number of stimuli in the task. The ThirdDT is a new method to measure somatosensory temporal discrimination and a possible index of inhibitory activity at the S1 level. Copyright © 2017 the American Physiological Society.

The use of interval ratios in consonance perception by rats (Rattus norvegicus) and humans (Homo sapiens).

PubMed

Crespo-Bojorque, Paola; Toro, Juan M

2015-02-01

Traditionally, physical features in musical chords have been proposed to be at the root of consonance perception. Alternatively, recent studies suggest that different types of experience modulate some perceptual foundations for musical sounds. The present study tested whether the mechanisms involved in the perception of consonance are present in an animal with no extensive experience with harmonic stimuli and a relatively limited vocal repertoire. In Experiment 1, rats were trained to discriminate consonant from dissonant chords and tested to explore whether they could generalize such discrimination to novel chords. In Experiment 2, we tested if rats could discriminate between chords differing only in their interval ratios and generalize them to different octaves. To contrast the observed pattern of results, human adults were tested with the same stimuli in Experiment 3. Rats successfully discriminated across chords in both experiments, but they did not generalize to novel items in either Experiment 1 or Experiment 2. On the contrary, humans not only discriminated among both consonance-dissonance categories, and among sets of interval ratios, they also generalized their responses to novel items. These results suggest that experience with harmonic sounds may be required for the construction of categories among stimuli varying in frequency ratios. However, the discriminative capacity observed in rats suggests that at least some components of auditory processing needed to distinguish chords based on their interval ratios are shared across species. PsycINFO Database Record (c) 2015 APA, all rights reserved.

Motor Timing Deficits in Sequential Movements in Parkinson Disease Are Related to Action Planning: A Motor Imagery Study

PubMed Central

Avanzino, Laura; Pelosin, Elisa; Martino, Davide; Abbruzzese, Giovanni

2013-01-01

Timing of sequential movements is altered in Parkinson disease (PD). Whether timing deficits in internally generated sequential movements in PD depends also on difficulties in motor planning, rather than merely on a defective ability to materially perform the planned movement is still undefined. To unveil this issue, we adopted a modified version of an established test for motor timing, i.e. the synchronization–continuation paradigm, by introducing a motor imagery task. Motor imagery is thought to involve mainly processes of movement preparation, with reduced involvement of end-stage movement execution-related processes. Fourteen patients with PD and twelve matched healthy volunteers were asked to tap in synchrony with a metronome cue (SYNC) and then, when the tone stopped, to keep tapping, trying to maintain the same rhythm (CONT-EXE) or to imagine tapping at the same rhythm, rather than actually performing it (CONT-MI). We tested both a sub-second and a supra-second inter-stimulus interval between the cues. Performance was recorded using a sensor-engineered glove and analyzed measuring the temporal error and the interval reproduction accuracy index. PD patients were less accurate than healthy subjects in the supra-second time reproduction task when performing both continuation tasks (CONT-MI and CONT-EXE), whereas no difference was detected in the synchronization task and on all tasks involving a sub-second interval. Our findings suggest that PD patients exhibit a selective deficit in motor timing for sequential movements that are separated by a supra-second interval and that this deficit may be explained by a defect of motor planning. Further, we propose that difficulties in motor planning are of a sufficient degree of severity in PD to affect also the motor performance in the supra-second time reproduction task. PMID:24086534

Timing and Causality in the Generation of Learned Eyelid Responses

PubMed Central

Sánchez-Campusano, Raudel; Gruart, Agnès; Delgado-García, José M.

2011-01-01

The cerebellum-red nucleus-facial motoneuron (Mn) pathway has been reported as being involved in the proper timing of classically conditioned eyelid responses. This special type of associative learning serves as a model of event timing for studying the role of the cerebellum in dynamic motor control. Here, we have re-analyzed the firing activities of cerebellar posterior interpositus (IP) neurons and orbicularis oculi (OO) Mns in alert behaving cats during classical eyeblink conditioning, using a delay paradigm. The aim was to revisit the hypothesis that the IP neurons (IPns) can be considered a neuronal phase-modulating device supporting OO Mns firing with an emergent timing mechanism and an explicit correlation code during learned eyelid movements. Optimized experimental and computational tools allowed us to determine the different causal relationships (temporal order and correlation code) during and between trials. These intra- and inter-trial timing strategies expanding from sub-second range (millisecond timing) to longer-lasting ranges (interval timing) expanded the functional domain of cerebellar timing beyond motor control. Interestingly, the results supported the above-mentioned hypothesis. The causal inferences were influenced by the precise motor and pre-motor spike timing in the cause-effect interval, and, in addition, the timing of the learned responses depended on cerebellar–Mn network causality. Furthermore, the timing of CRs depended upon the probability of simulated causal conditions in the cause-effect interval and not the mere duration of the inter-stimulus interval. In this work, the close relation between timing and causality was verified. It could thus be concluded that the firing activities of IPns may be related more to the proper performance of ongoing CRs (i.e., the proper timing as a consequence of the pertinent causality) than to their generation and/or initiation. PMID:21941469

Timescale- and Sensory Modality-Dependency of the Central Tendency of Time Perception.

PubMed

Murai, Yuki; Yotsumoto, Yuko

2016-01-01

When individuals are asked to reproduce intervals of stimuli that are intermixedly presented at various times, longer intervals are often underestimated and shorter intervals overestimated. This phenomenon may be attributed to the central tendency of time perception, and suggests that our brain optimally encodes a stimulus interval based on current stimulus input and prior knowledge of the distribution of stimulus intervals. Two distinct systems are thought to be recruited in the perception of sub- and supra-second intervals. Sub-second timing is subject to local sensory processing, whereas supra-second timing depends on more centralized mechanisms. To clarify the factors that influence time perception, the present study investigated how both sensory modality and timescale affect the central tendency. In Experiment 1, participants were asked to reproduce sub- or supra-second intervals, defined by visual or auditory stimuli. In the sub-second range, the magnitude of the central tendency was significantly larger for visual intervals compared to auditory intervals, while visual and auditory intervals exhibited a correlated and comparable central tendency in the supra-second range. In Experiment 2, the ability to discriminate sub-second intervals in the reproduction task was controlled across modalities by using an interval discrimination task. Even when the ability to discriminate intervals was controlled, visual intervals exhibited a larger central tendency than auditory intervals in the sub-second range. In addition, the magnitude of the central tendency for visual and auditory sub-second intervals was significantly correlated. These results suggest that a common modality-independent mechanism is responsible for the supra-second central tendency, and that both the modality-dependent and modality-independent components of the timing system contribute to the central tendency in the sub-second range.

Event related aspects of somatosensory and auditory evoked potentials: noise or signals?

PubMed

Stowell, H

1985-05-01

The so-called Vertex Potential (VP) of human scalp-conducted and event related brain potential (ERBP), which occur as a slow and often large, biphasic sinusoid within the 100-400 msec time segment after transient stimulation in the three main sensory modalities, are the longest researched of all human evoked potential (EP) phenomena. Its variable amplitude has been directly correlated, in experiments expressly tailored for the purpose, with input/output variables such as the rate of acceleration of given stimulus parameters from a state of relative rest (RM function), interstimulus interval (ISI), stimulus intensity, skin potential and resistance changes (SPR and SRR), the peripheral electroneurogram (ENG), and experimentally isolated C-fiber afference; and with neuropsychological variables such as attention or vigilance, visual acuity, response time, subjective stimulus probability or expectancy, acute pain of both fast and slow kinds, intelligence quotient (IQ), and psychometric personality scores (e.g., extraversion versus introversion and neuroticism versus normality). Unfortunately, the cerebral, neural origins of the VP, if any, are unknown; it is reported as usually absent from cortex-surface EP in those primates and mammals hitherto studied, and also from human extracranial event related magnetic fields of the brain (ERMFb) insofar as these reveal only superficial tangential sources; but a possible analog has been recorded from deep subcortical electrodes during human neurosurgery. In view of the increasing published range and quantity of direct correlates of VP amplitude, and of the scarcity of data about its neuroanatomy and neurophysiology, it seemed a good idea to do some rudimentary signal analysis. Preliminary results from five subjects confirm earlier data: The VP of somatosensory (SEP) and auditory (AEP) evoked potentials, as obtained by scalp-conductance and either averaged or single-epoch, can be resolved into inconsistently stimulus synchronized frequency components which are also present as relatively unsynchronized waves in the theta and alpha bands (approx. 2-13 Hz) of the unstimulated or near-threshold-stimulated electroencephalogram (EEG). In averages of numerous single trials (20 less than N less than 102), initiated at interstimulus intervals longer than 2.5 sec and deliberately sequenced so that the initiator could learn to estimate the timing of stimulus onsets, the phase coherence of the power-dominant alpha and theta waves within the 100-400 msec time segment of ERBP is obvious when the stimulus is an intense transient and psychologically not "habituated".(ABSTRACT TRUNCATED AT 400 WORDS)

Selective Attention in Pigeon Temporal Discrimination.

PubMed

Subramaniam, Shrinidhi; Kyonka, Elizabeth

2017-07-27

Cues can vary in how informative they are about when specific outcomes, such as food availability, will occur. This study was an experimental investigation of the functional relation between cue informativeness and temporal discrimination in a peak-interval (PI) procedure. Each session consisted of fixed-interval (FI) 2-s and 4-s schedules of food and occasional, 12-s PI trials during which pecks had no programmed consequences. Across conditions, the phi (ϕ) correlation between key light color and FI schedule value was manipulated. Red and green key lights signaled the onset of either or both FI schedules. Different colors were either predictive (ϕ = 1), moderately predictive (ϕ = 0.2-0.8), or not predictive (ϕ = 0) of a specific FI schedule. This study tested the hypothesis that temporal discrimination is a function of the momentary conditional probability of food; that is, pigeons peck the most at either 2 s or 4 s when ϕ = 1 and peck at both intervals when ϕ < 1. Response distributions were bimodal Gaussian curves; distributions from red- and green-key PI trials converged when ϕ ≤ 0.6. Peak times estimated by summed Gaussian functions, averaged across conditions and pigeons, were 1.85 s and 3.87 s, however, pigeons did not always maximize the momentary probability of food. When key light color was highly correlated with FI schedules (ϕ ≥ 0.6), estimates of peak times indicated that temporal discrimination accuracy was reduced at the unlikely interval, but not the likely interval. The mechanism of this reduced temporal discrimination accuracy could be interpreted as an attentional process.

Differing Presynaptic Contributions to LTP and Associative Learning in Behaving Mice

PubMed Central

Madroñal, Noelia; Gruart, Agnès; Delgado-García, José M.

2009-01-01

The hippocampal CA3-CA1 synapse is an excellent experimental model for studying the interactions between short- and long-term plastic changes taking place following high-frequency stimulation (HFS) of Schaffer collaterals and during the acquisition and extinction of a classical eyeblink conditioning in behaving mice. Input/output curves and a full-range paired-pulse study enabled determining the optimal intensities and inter-stimulus intervals for evoking paired-pulse facilitation (PPF) or depression (PPD) at the CA3-CA1 synapse. Long-term potentiation (LTP) induced by HFS lasted ≈10 days. HFS-induced LTP evoked an initial depression of basal PPF. Recovery of PPF baseline values was a steady and progressive process lasting ≈20 days, i.e., longer than the total duration of the LTP. In a subsequent series of experiments, we checked whether PPF was affected similarly during activity-dependent synaptic changes. Animals were conditioned using a trace paradigm, with a tone as a conditioned stimulus (CS) and an electrical shock to the trigeminal nerve as an unconditioned stimulus (US). A pair of pulses (40 ms interval) was presented to the Schaffer collateral-commissural pathway to evoke field EPSPs (fEPSPs) during the CS-US interval. Basal PPF decreased steadily across conditioning sessions (i.e., in the opposite direction to that during LTP), reaching a minimum value during the 10th conditioning session. Thus, LTP and classical eyeblink conditioning share some presynaptic mechanisms, but with an opposite evolution. Furthermore, PPF and PPD might play a homeostatic role during long-term plastic changes at the CA3-CA1 synapse. PMID:19636387

The Effects of Short Interval Delay of Reinforcement Upon Human Discrimination Learning. IMRID Papers and Reports Vol. 4 No. 12.

ERIC Educational Resources Information Center

Kral, Paul A.; And Others

Investigates the effect of delay of reinforcement upon human discrimination learning with particular emphasis on the form of the gradient within the first few seconds of delay. In previous studies subjects are usually required to make an instrumental response to a stimulus, this is followed by the delay interval, and finally, the reinforcement…

Filling the blanks in temporal intervals: the type of filling influences perceived duration and discrimination performance

PubMed Central

Horr, Ninja K.; Di Luca, Massimiliano

2015-01-01

In this work we investigate how judgments of perceived duration are influenced by the properties of the signals that define the intervals. Participants compared two auditory intervals that could be any combination of the following four types: intervals filled with continuous tones (filled intervals), intervals filled with regularly-timed short tones (isochronous intervals), intervals filled with irregularly-timed short tones (anisochronous intervals), and intervals demarcated by two short tones (empty intervals). Results indicate that the type of intervals to be compared affects discrimination performance and induces distortions in perceived duration. In particular, we find that duration judgments are most precise when comparing two isochronous and two continuous intervals, while the comparison of two anisochronous intervals leads to the worst performance. Moreover, we determined that the magnitude of the distortions in perceived duration (an effect akin to the filled duration illusion) is higher for tone sequences (no matter whether isochronous or anisochronous) than for continuous tones. Further analysis of how duration distortions depend on the type of filling suggests that distortions are not only due to the perceived duration of the two individual intervals, but they may also be due to the comparison of two different filling types. PMID:25717310

Disruption of trace conditioning of the nictitating membrane response in rabbits by central cholinergic blockade.

PubMed

Kaneko, T; Thompson, R F

1997-05-01

Central muscarinic cholinergic involvement in classical conditioning of eyeblink responses was determined in trace and delay paradigms. Rabbits were trained on a trace procedure in which a 250-ms tone conditioned stimulus (CS) and a 100-ms air-puff unconditioned stimulus (UCS) were presented with a 500-ms trace interval. Each training session day consisted of ten tone alone, ten air-puff alone and 80 paired CS-UCS trials. Scopolamine hydrochloride at doses of 0.03 and 0.1 mg/0.5 ml per kg, s.c. dose-dependently disrupted acquisition of conditioned responses. Rabbits that were treated with scopolamine and failed to learn showed a gradual increase in conditioned responses during an additional training period with saline injections and no transfer from earlier training. Scopolamine methyl bromide, which does not appreciably cross the blood-brain barrier, showed no effects in the trace conditioning paradigm at a dose of 0.1 mg/kg, s.c., indicating central cholinergic blockade is responsible for the suppressive effect of scopolamine. Scopolamine hydrochloride at a dose of 0.1 mg/kg, s.c. did not block acquisition in the delay procedure with a 250-ms inter-stimulus interval, although the rate of acquisition was somewhat reduced by the drug. These data are the first to demonstrate that classical conditioning of the eyeblink response in the trace procedure is highly sensitive to central cholinergic deficits.

Pigeons (Columba livia) show change blindness in a color-change detection task.

PubMed

Herbranson, Walter T; Jeffers, Jacob S

2017-07-01

Change blindness is a phenomenon whereby changes to a stimulus are more likely go unnoticed under certain circumstances. Pigeons learned a change detection task, in which they observed sequential stimulus displays consisting of individual colors back-projected onto three response keys. The color of one response key changed during each sequence and pecks to the key that displayed the change were reinforced. Pigeons showed a change blindness effect, in that change detection accuracy was worse when there was an inter-stimulus interval interrupting the transition between consecutive stimulus displays. Birds successfully transferred to stimulus displays involving novel colors, indicating that pigeons learned a general change detection rule. Furthermore, analysis of responses to specific color combinations showed that pigeons could detect changes involving both spectral and non-spectral colors and that accuracy was better for changes involving greater differences in wavelength. These results build upon previous investigations of change blindness in both humans and pigeons and suggest that change blindness may be a general consequence of selective visual attention relevant to multiple species and stimulus dimensions.

The ventral tegmental area modulates intracortical microstimulation (ICMS)-evoked M1 activity in a time-dependent manner.

PubMed

Kunori, Nobuo; Kajiwara, Riichi; Takashima, Ichiro

2016-03-11

Intracortical microstimulation (ICMS)-evoked neural activity combined with ventral tegmental area (VTA) stimulation was studied in rat primary motor cortex (M1). We used voltage-sensitive dye (VSD) imaging to analyze the spatiotemporal dynamics of M1 activity following VTA-M1 paired stimulation. VTA stimulation was preceded by M1 ICMS at inter-stimulus intervals (ISIs) of 15-350ms. VSD imaging showed an excitatory-inhibitory sequence of neural activity after composing VTA stimulus- and ICMS-induced M1 neural activity. To evaluate the net ICMS M1 response, the optical response to unpaired VTA stimulation was subtracted from the VTA-M1 paired response. This revealed that the net ICMS-evoked M1 neural activity was inhibited when the ISI was 30-50ms, but highly facilitated when the ISI was 100-350ms. These results suggest that VTA modulates M1 excitability in the order of tens to hundreds of milliseconds and might directly affect the motor command generation process in the M1. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Dissociating emotion-induced blindness and hypervision.

PubMed

Bocanegra, Bruno R; Zeelenberg, René

2009-12-01

Previous findings suggest that emotional stimuli sometimes improve (emotion-induced hypervision) and sometimes impair (emotion-induced blindness) the visual perception of subsequent neutral stimuli. We hypothesized that these differential carryover effects might be due to 2 distinct emotional influences in visual processing. On the one hand, emotional stimuli trigger a general enhancement in the efficiency of visual processing that can carry over onto other stimuli. On the other hand, emotional stimuli benefit from a stimulus-specific enhancement in later attentional processing at the expense of competing visual stimuli. We investigated whether detrimental (blindness) and beneficial (hypervision) carryover effects of emotion in perception can be dissociated within a single experimental paradigm. In 2 experiments, we manipulated the temporal competition for attention between an emotional cue word and a subsequent neutral target word by varying cue-target interstimulus interval (ISI) and cue visibility. Interestingly, emotional cues impaired target identification at short ISIs but improved target identification when competition was diminished by either increasing ISI or reducing cue visibility, suggesting that emotional significance of stimuli can improve and impair visual performance through distinct perceptual mechanisms.

Single-trial event-related potentials to significant stimuli.

PubMed

Rushby, Jacqueline A; Barry, Robert J

2009-11-01

The stimulus-response pattern of the skin conductance response (SCR) was used as a model of the Orienting Reflex (OR) to assess the P1, N1, P2, N2 and late positive complex (LPC/P300) components of the ERP in a simple habituation paradigm, in which a single series of 12 innocuous tones were presented at a very long interstimulus interval (2 min). To maintain their waking state during this boring task, participants were instructed to alternately close or open their eyes to each stimulus. None of the baseline-to-peak ERP measures showed trials effects comparable with the marked habituation over trials shown by the SCRs. Principal Components Analysis was used to decompose the ERP, yielding factors identified as the N1, N2, P3a, P3b and Novelty P3 components. An additional factor represented later eye-movement activity. No trial effects were apparent for the N1, N2, P3a or P3b components. The Novelty P3 showed marked response decrement over trials. These results are discussed in relation to current conceptualisations of the OR.

The effect of spatio-temporal distance between visual stimuli on information processing in children with Specific Language Impairment.

PubMed

Dispaldro, Marco; Corradi, Nicola

2015-01-01

The purpose of this study is to evaluate whether children with Specific Language Impairment (SLI) have a deficit in processing a sequence of two visual stimuli (S1 and S2) presented at different inter-stimulus intervals and in different spatial locations. In particular, the core of this study is to investigate whether S1 identification is disrupted due to a retroactive interference of S2. To this aim, two experiments were planned in which children with SLI and children with typical development (TD), matched by age and non-verbal IQ, were compared (Experiment 1: SLI n=19; TD n=19; Experiment 2: SLI n=16; TD n=16). Results show group differences in the ability to identify a single stimulus surrounded by flankers (Baseline level). Moreover, children with SLI show a stronger negative interference of S2, both for temporal and spatial modulation. These results are discussed in the light of an attentional processing limitation in children with SLI. Copyright © 2015 Elsevier Ltd. All rights reserved.

The role of dopamine in the timing of Pavlovian conditioned keypecking in ring doves.

PubMed

Ohyama, T; Horvitz, J C; Kitsos, E; Balsam, P D

2001-01-01

The effect of dopaminergic drugs on the timing of conditioned keypecking in ring doves was studied in two experiments. Subjects were given pairings of a keylight with food and the temporal distribution of keypecks was obtained during unreinforced probe trials. Experiment 1 demonstrated that injections of pimozide before each session immediately decreased response rates but shifted timing distributions gradually to the right over several days of treatment. Experiment 2 showed similar results using a longer interstimulus interval (ISI). No shifts were observed when the drug was injected after training sessions, or when a delay, identical to each subject's average latency to eat during the drug condition, was inserted between keylight offset and food presentation. Consequently, the shifts in timing were mediated neither by mere accumulation of the drug nor a delay from keylight offset to food presentation resulting from the drug's ability to slow motor processes. The results suggest that pimozide modulates response rate through its effect on motor processes or incentive value, and response timing through a conditioned response (CR) to injection-related cues established via their repeated pairings with the drug.

Character Decomposition and Transposition Processes of Chinese Compound Words in Rapid Serial Visual Presentation.

PubMed

Cao, Hong-Wen; Yang, Ke-Yu; Yan, Hong-Mei

2017-01-01

Character order information is encoded at the initial stage of Chinese word processing, however, its time course remains underspecified. In this study, we assess the exact time course of the character decomposition and transposition processes of two-character Chinese compound words (canonical, transposed, or reversible words) compared with pseudowords using dual-target rapid serial visual presentation (RSVP) of stimuli appearing at 30 ms per character with no inter-stimulus interval. The results indicate that Chinese readers can identify words with character transpositions in rapid succession; however, a transposition cost is involved in identifying transposed words compared to canonical words. In RSVP reading, character order of words is more likely to be reversed during the period from 30 to 180 ms for canonical and reversible words, but the period from 30 to 240 ms for transposed words. Taken together, the findings demonstrate that the holistic representation of the base word is activated, however, the order of the two constituent characters is not strictly processed during the very early stage of visual word processing.

The ex-Gaussian distribution of reaction times in adolescents with attention-deficit/hyperactivity disorder.

PubMed

Gu, Shoou-Lian Hwang; Gau, Susan Shur-Fen; Tzang, Shyh-Weir; Hsu, Wen-Yau

2013-11-01

We investigated the three parameters (mu, sigma, tau) of ex-Gaussian distribution of RT derived from the Conners' continuous performance test (CCPT) and examined the moderating effects of the energetic factors (the inter-stimulus intervals (ISIs) and Blocks) among these three parameters, especially tau, an index describing the positive skew of RT distribution. We assessed 195 adolescents with DSM-IV ADHD, and 90 typically developing (TD) adolescents, aged 10-16. Participants and their parents received psychiatric interviews to confirm the diagnosis of ADHD and other psychiatric disorders. Participants also received intelligence (WISC-III) and CCPT assessments. We found that participants with ADHD had a smaller mu, and larger tau. As the ISI/Block increased, the magnitude of group difference in tau increased. Among the three ex-Gaussian parameters, tau was positively associated with omission errors, and mu was negatively associated with commission errors. The moderating effects of ISIs and Blocks on tau parameters suggested that the ex-Gaussian parameters could offer more information about the attention state in vigilance task, especially in ADHD. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Possible Link between Supra-Second Open-Ended Timing Sensitivity and Obsessive-Compulsive Tendencies

PubMed Central

Gilaie-Dotan, Sharon; Ashkenazi, Hamutal; Dar, Reuven

2016-01-01

One of the main characteristics of obsessive-compulsive disorder (OCD) is the persistent feeling of uncertainty, affecting many domains of actions and feelings. It was recently hypothesized that OCD uncertainty is related to attenuated access to internal states. As supra-second timing is associated with bodily and interoceptive awareness, we examined whether supra-second timing would be associated with OC tendencies. We measured supra-second (~9 s) and sub-second (~450 ms) timing along with control non-temporal perceptual tasks in a group of 60 university students. Supra-second timing was measured either with fixed criterion tasks requiring to temporally discriminate between two predefined fixed interval durations (9 vs. 9.9 s), or with an open-ended task requiring to discriminate between 9 s and longer intervals which were of varying durations that were not a priori known to the participants. The open-ended task employed an adaptive Bayesian procedure that efficiently estimated the duration difference required to discriminate 9 s from longer intervals. We also assessed symptoms of OCD, depression, and anxiety. Open-ended supra-second temporal sensitivity was correlated with OC tendencies, as predicted (even after controlling for depression and anxiety), whereas the other tasks were not. Higher OC tendencies were associated with lower timing sensitivity to 9 s intervals such that participants with higher OC tendency scores required longer interval differences to discriminate 9 s from longer intervals. While these results need to be substantiated in future research, they suggest that open-ended timing tasks, as those encountered in real-life (e.g., estimating how long it would take to complete a task), might be adversely affected in OCD. PMID:27445725

Humans do not have direct access to retinal flow during walking

PubMed Central

Souman, Jan L.; Freeman, Tom C.A.; Eikmeier, Verena; Ernst, Marc O.

2013-01-01

Perceived visual speed has been reported to be reduced during walking. This reduction has been attributed to a partial subtraction of walking speed from visual speed (Durgin & Gigone, 2007; Durgin, Gigone, & Scott, 2005). We tested whether observers still have access to the retinal flow before subtraction takes place. Observers performed a 2IFC visual speed discrimination task while walking on a treadmill. In one condition, walking speed was identical in the two intervals, while in a second condition walking speed differed between intervals. If observers have access to the retinal flow before subtraction, any changes in walking speed across intervals should not affect their ability to discriminate retinal flow speed. Contrary to this “direct-access hypothesis”, we found that observers were worse at discrimination when walking speed differed between intervals. The results therefore suggest that observers do not have access to retinal flow before subtraction. We also found that the amount of subtraction depended on the visual speed presented, suggesting that the interaction between the processing of visual input and of self-motion is more complex than previously proposed. PMID:20884509

Adaptation to visual or auditory time intervals modulates the perception of visual apparent motion

PubMed Central

Zhang, Huihui; Chen, Lihan; Zhou, Xiaolin

2012-01-01

It is debated whether sub-second timing is subserved by a centralized mechanism or by the intrinsic properties of task-related neural activity in specific modalities (Ivry and Schlerf, 2008). By using a temporal adaptation task, we investigated whether adapting to different time intervals conveyed through stimuli in different modalities (i.e., frames of a visual Ternus display, visual blinking discs, or auditory beeps) would affect the subsequent implicit perception of visual timing, i.e., inter-stimulus interval (ISI) between two frames in a Ternus display. The Ternus display can induce two percepts of apparent motion (AM), depending on the ISI between the two frames: “element motion” for short ISIs, in which the endmost disc is seen as moving back and forth while the middle disc at the overlapping or central position remains stationary; “group motion” for longer ISIs, in which both discs appear to move in a manner of lateral displacement as a whole. In Experiment 1, participants adapted to either the typical “element motion” (ISI = 50 ms) or the typical “group motion” (ISI = 200 ms). In Experiments 2 and 3, participants adapted to a time interval of 50 or 200 ms through observing a series of two paired blinking discs at the center of the screen (Experiment 2) or hearing a sequence of two paired beeps (with pitch 1000 Hz). In Experiment 4, participants adapted to sequences of paired beeps with either low pitches (500 Hz) or high pitches (5000 Hz). After adaptation in each trial, participants were presented with a Ternus probe in which the ISI between the two frames was equal to the transitional threshold of the two types of motions, as determined by a pretest. Results showed that adapting to the short time interval in all the situations led to more reports of “group motion” in the subsequent Ternus probes; adapting to the long time interval, however, caused no aftereffect for visual adaptation but significantly more reports of group motion for auditory adaptation. These findings, suggesting amodal representation for sub-second timing across modalities, are interpreted in the framework of temporal pacemaker model. PMID:23133408

Memory for Multiple Cache Locations and Prey Quantities in a Food-Hoarding Songbird

PubMed Central

Armstrong, Nicola; Garland, Alexis; Burns, K. C.

2012-01-01

Most animals can discriminate between pairs of numbers that are each less than four without training. However, North Island robins (Petroica longipes), a food-hoarding songbird endemic to New Zealand, can discriminate between quantities of items as high as eight without training. Here we investigate whether robins are capable of other complex quantity discrimination tasks. We test whether their ability to discriminate between small quantities declines with (1) the number of cache sites containing prey rewards and (2) the length of time separating cache creation and retrieval (retention interval). Results showed that subjects generally performed above-chance expectations. They were equally able to discriminate between different combinations of prey quantities that were hidden from view in 2, 3, and 4 cache sites from between 1, 10, and 60 s. Overall results indicate that North Island robins can process complex quantity information involving more than two discrete quantities of items for up to 1 min long retention intervals without training. PMID:23293622

Memory for multiple cache locations and prey quantities in a food-hoarding songbird.

PubMed

Armstrong, Nicola; Garland, Alexis; Burns, K C

2012-01-01

Most animals can discriminate between pairs of numbers that are each less than four without training. However, North Island robins (Petroica longipes), a food-hoarding songbird endemic to New Zealand, can discriminate between quantities of items as high as eight without training. Here we investigate whether robins are capable of other complex quantity discrimination tasks. We test whether their ability to discriminate between small quantities declines with (1) the number of cache sites containing prey rewards and (2) the length of time separating cache creation and retrieval (retention interval). Results showed that subjects generally performed above-chance expectations. They were equally able to discriminate between different combinations of prey quantities that were hidden from view in 2, 3, and 4 cache sites from between 1, 10, and 60 s. Overall results indicate that North Island robins can process complex quantity information involving more than two discrete quantities of items for up to 1 min long retention intervals without training.

Impaired induction of long-term potentiation-like plasticity in patients with high-functioning autism and Asperger syndrome.

PubMed

Jung, Nikolai H; Janzarik, Wibke G; Delvendahl, Igor; Münchau, Alexander; Biscaldi, Monica; Mainberger, Florian; Bäumer, Tobias; Rauh, Reinhold; Mall, Volker

2013-01-01

We aimed to investigate the induction of long-term potentiation (LTP)-like plasticity by paired associative stimulation (PAS) in patients with high-functioning autism and Asperger syndrome (HFA/AS). PAS with an interstimulus interval between electrical and transcranial magnetic stimulation of 25 ms (PAS(25)) was performed in patients with HFA/AS (n=9; eight males, one female; mean age 17 y 11 mo, SD 4 y 5 mo) and in typically developing age-matched volunteers (n=9; five males, four females; mean age 22 y 4 mo, SD 5 y 2 mo). The amplitude of motor-evoked potentials was measured before PAS(25), immediately after stimulation, and 30 minutes and 60 minutes later. A PAS protocol adapted to individual N20 latency (PAS(N20+2)) was performed in six additional patients with HFA/AS. Short-interval intracortical inhibition was measured using paired-pulse stimulation. In contrast to the typically developing participants, the patients with HFA/AS did not show a significant increase in motor-evoked potentials after PAS(25). This finding could also be demonstrated after adaptation for N20 latency. Short-interval intracortical inhibition of patients with HFA/AS was normal compared with the comparison group and did not correlate with PAS effect. Our results show a significant impairment of LTP-like plasticity induced by PAS in individuals with HFA/AS compared with typically developing participants. This finding is in accordance with results from animal studies as well as human studies. Impaired LTP-like plasticity in patients with HFA/AS points towards reduced excitatory synaptic connectivity and deficits in sensory-motor integration in these patients. © The Authors. Developmental Medicine & Child Neurology © 2012 Mac Keith Press.

Influence of waveform and current direction on short-interval intracortical facilitation: a paired-pulse TMS study.

PubMed

Delvendahl, Igor; Lindemann, Hannes; Jung, Nikolai H; Pechmann, Astrid; Siebner, Hartwig R; Mall, Volker

2014-01-01

Transcranial magnetic stimulation (TMS) of the human primary motor hand area (M1-HAND) can produce multiple descending volleys in fast-conducting corticospinal neurons, especially so-called indirect waves (I-waves) resulting from trans-synaptic excitation. Facilitatory interaction between these I-waves can be studied non-invasively using a paired-pulse paradigm referred to as short-interval intracortical facilitation (SICF). We examined whether SICF depends on waveform and current direction of the TMS pulses. In young healthy volunteers, we applied single- and paired-pulse TMS to M1-HAND. We probed SICF by pairs of monophasic or half-sine pulses at suprathreshold stimulation intensity and inter-stimulus intervals (ISIs) between 1.0 and 5.0 ms. For monophasic paired-pulse stimulation, both pulses had either a posterior-anterior (PA) or anterior-posterior (AP) current direction (AP-AP or PA-PA), whereas current direction was reversed between first and second pulse for half-sine paired-pulse stimulation (PA-AP and AP-PA). Monophasic AP-AP stimulation resulted in stronger early SICF at 1.4 ms relative to late SICF at 2.8 and 4.4 ms, whereas monophasic PA-PA stimulation produced SICF of comparable size at all three peaks. With half-sine stimulation the third SICF peak was reduced for PA-AP current orientation compared with AP-PA. SICF elicited using monophasic as well as half-sine pulses is affected by current direction at clearly suprathreshold intensities. The impact of current orientation is stronger for monophasic compared with half-sine pulses. The direction-specific effect of paired-pulse TMS on the strength of early versus late SICF shows that different cortical circuits mediate early and late SICF. Copyright © 2014 Elsevier Inc. All rights reserved.

Did I see your hand moving? The effect of movement-related information on the Corsi block tapping task.

PubMed

Brunetti, Riccardo; Del Gatto, Claudia; Cavallina, Clarissa; Farina, Benedetto; Delogu, Franco

2018-05-01

The Corsi Block Tapping Task is a widespread test used to assess spatial working memory. Previous research hypothesized that the discrepancy found in some cases between the traditional and the digital (touchscreen) version of the Corsi block tapping task may be due to a direct motor resonance between the experimenter's and the participant's hand movements. However, we hypothesize that this discrepancy might be due to extra movement-related information included in the traditional version, lacking in the digital one. We investigated the effects of such task-irrelevant information using eCorsi, a touchscreen version of the task. In Experiment 1, we manipulate timing in sequence presentation, creating three conditions. In the Congruent condition, the inter-stimulus intervals reflected the physical distance in which the stimuli were spatially placed: The longer the spatial distance, the longer the temporal interval. In the Incongruent condition the timing changed randomly. Finally, in the Isochronous condition every stimulus appeared after a fixed interval, independently from its spatial position. The results showed a performance enhancement in the Congruent condition, suggesting an incidental spatio-temporal binding. In Experiment 2, we added straight lines between each location in the sequences: In the Trajectories condition participants saw trajectories from one spatial position to the other during sequence presentation, while a condition without such trajectories served as control. Results showed better performances in the Trajectories condition. We suggest that the timing and trajectories information play a significant role in the discrepancies found between the traditional and the touchscreen version of the Corsi Block Tapping Task, without the necessity of explanations involving direct motor resonance (e.g. seeing an actual hand moving) as a causal factor.

Why trace and delay conditioning are sometimes (but not always) hippocampal dependent: A computational model

PubMed Central

Moustafa, Ahmed A.; Wufong, Ella; Servatius, Richard J.; Pang, Kevin C. H.; Gluck, Mark A.; Myers, Catherine E.

2013-01-01

A recurrent-network model provides a unified account of the hippocampal region in mediating the representation of temporal information in classical eyeblink conditioning. Much empirical research is consistent with a general conclusion that delay conditioning (in which the conditioned stimulus CS and unconditioned stimulus US overlap and co-terminate) is independent of the hippocampal system, while trace conditioning (in which the CS terminates before US onset) depends on the hippocampus. However, recent studies show that, under some circumstances, delay conditioning can be hippocampal-dependent and trace conditioning can be spared following hippocampal lesion. Here, we present an extension of our prior trial-level models of hippocampal function and stimulus representation that can explain these findings within a unified framework. Specifically, the current model includes adaptive recurrent collateral connections that aid in the representation of intra-trial temporal information. With this model, as in our prior models, we argue that the hippocampus is not specialized for conditioned response timing, but rather is a general-purpose system that learns to predict the next state of all stimuli given the current state of variables encoded by activity in recurrent collaterals. As such, the model correctly predicts that hippocampal involvement in classical conditioning should be critical not only when there is an intervening trace interval, but also when there is a long delay between CS onset and US onset. Our model simulates empirical data from many variants of classical conditioning, including delay and trace paradigms in which the length of the CS, the inter-stimulus interval, or the trace interval is varied. Finally, we discuss model limitations, future directions, and several novel empirical predictions of this temporal processing model of hippocampal function and learning. PMID:23178699

The Chronometry of Mental Ability: An Event-Related Potential Analysis of an Auditory Oddball Discrimination Task

ERIC Educational Resources Information Center

Beauchamp, Chris M.; Stelmack, Robert M.

2006-01-01

The relation between intelligence and speed of auditory discrimination was investigated during an auditory oddball task with backward masking. In target discrimination conditions that varied in the interval between the target and the masking stimuli and in the tonal frequency of the target and masking stimuli, higher ability participants (HA)…

Shared and Distinct Rupture Discriminants of Small and Large Intracranial Aneurysms.

PubMed

Varble, Nicole; Tutino, Vincent M; Yu, Jihnhee; Sonig, Ashish; Siddiqui, Adnan H; Davies, Jason M; Meng, Hui

2018-04-01

Many ruptured intracranial aneurysms (IAs) are small. Clinical presentations suggest that small and large IAs could have different phenotypes. It is unknown if small and large IAs have different characteristics that discriminate rupture. We analyzed morphological, hemodynamic, and clinical parameters of 413 retrospectively collected IAs (training cohort; 102 ruptured IAs). Hierarchal cluster analysis was performed to determine a size cutoff to dichotomize the IA population into small and large IAs. We applied multivariate logistic regression to build rupture discrimination models for small IAs, large IAs, and an aggregation of all IAs. We validated the ability of these 3 models to predict rupture status in a second, independently collected cohort of 129 IAs (testing cohort; 14 ruptured IAs). Hierarchal cluster analysis in the training cohort confirmed that small and large IAs are best separated at 5 mm based on morphological and hemodynamic features (area under the curve=0.81). For small IAs (<5 mm), the resulting rupture discrimination model included undulation index, oscillatory shear index, previous subarachnoid hemorrhage, and absence of multiple IAs (area under the curve=0.84; 95% confidence interval, 0.78-0.88), whereas for large IAs (≥5 mm), the model included undulation index, low wall shear stress, previous subarachnoid hemorrhage, and IA location (area under the curve=0.87; 95% confidence interval, 0.82-0.93). The model for the aggregated training cohort retained all the parameters in the size-dichotomized models. Results in the testing cohort showed that the size-dichotomized rupture discrimination model had higher sensitivity (64% versus 29%) and accuracy (77% versus 74%), marginally higher area under the curve (0.75; 95% confidence interval, 0.61-0.88 versus 0.67; 95% confidence interval, 0.52-0.82), and similar specificity (78% versus 80%) compared with the aggregate-based model. Small (<5 mm) and large (≥5 mm) IAs have different hemodynamic and clinical, but not morphological, rupture discriminants. Size-dichotomized rupture discrimination models performed better than the aggregate model. © 2018 American Heart Association, Inc.

Racial discrimination, response to unfair treatment, and depressive symptoms among pregnant black and African American women in the United States.

PubMed

Ertel, Karen A; James-Todd, Tamarra; Kleinman, Kenneth; Krieger, Nancy; Gillman, Matthew; Wright, Rosalind; Rich-Edwards, Janet

2012-12-01

To assess the association between self-reported racial discrimination and prenatal depressive symptoms among black women. Our study population consisted of two cohorts of pregnant women: the Asthma Coalition on Community, Environment, and Social Stress project (ACCESS) and Project Viva. We measured self-reported racial discrimination among black women using a modified Experiences of Discrimination scale (score 0-8). We assessed elevated depressive symptoms (EDS) with the Edinburgh Postnatal Depression Scale (≥13 on a 0-30 scale). Fifty-four percent of ACCESS and 78% of Viva participants reported experiencing racial discrimination. After adjusting for age, marital status, income, education, and nativity, a 1-U increment in Experiences of Discrimination score was associated with 48% increased odds of EDS (odds ratio, 1.48; 95% confidence interval, 1.24-1.76) for ACCESS participants but was not significantly associated among Viva participants (odds ratio, 1.12; 95% confidence interval, 0.92-1.37). In both cohorts, responding to unfair treatment by talking to others was associated with the lowest odds of EDS. Our findings suggest that higher levels of perceived racial discrimination may increase depressive symptoms during pregnancy among U.S. black women. Interventions involving talking to others may aid in reducing the risk of depressive symptoms among black women experiencing higher levels of racial discrimination. Copyright © 2012 Elsevier Inc. All rights reserved.

Interval and Contour Processing in Autism

ERIC Educational Resources Information Center

Heaton, Pamela

2005-01-01

High functioning children with autism and age and intelligence matched controls participated in experiments testing perception of pitch intervals and musical contours. The finding from the interval study showed superior detection of pitch direction over small pitch distances in the autism group. On the test of contour discrimination no group…

The Time Is Up: Compression of Visual Time Interval Estimations of Bimodal Aperiodic Patterns

PubMed Central

Duarte, Fabiola; Lemus, Luis

2017-01-01

The ability to estimate time intervals subserves many of our behaviors and perceptual experiences. However, it is not clear how aperiodic (AP) stimuli affect our perception of time intervals across sensory modalities. To address this question, we evaluated the human capacity to discriminate between two acoustic (A), visual (V) or audiovisual (AV) time intervals of trains of scattered pulses. We first measured the periodicity of those stimuli and then sought for correlations with the accuracy and reaction times (RTs) of the subjects. We found that, for all time intervals tested in our experiment, the visual system consistently perceived AP stimuli as being shorter than the periodic (P) ones. In contrast, such a compression phenomenon was not apparent during auditory trials. Our conclusions are: first, the subjects exposed to P stimuli are more likely to measure their durations accurately. Second, perceptual time compression occurs for AP visual stimuli. Lastly, AV discriminations are determined by A dominance rather than by AV enhancement. PMID:28848406

A temporal discriminability account of children's eyewitness suggestibility.

PubMed

Bright-Paul, Alexandra; Jarrold, Christopher

2009-07-01

Children's suggestibility is typically measured using a three-stage 'event-misinformation-test' procedure. We examined whether suggestibility is influenced by the time delays imposed between these stages, and in particular whether the temporal discriminability of sources (event and misinformation) predicts performance. In a novel approach, the degree of source discriminability was calculated as the relative magnitude of two intervals (the ratio of event-misinformation and misinformation-test intervals), based on an adaptation of existing 'ratio-rule' accounts of memory. Five-year-olds (n =150) watched an event, and were exposed to misinformation, before memory for source was tested. The absolute event-test delay (12 versus 24 days) and the 'ratio' of event-misinformation/misinformation-test intervals (11:1, 3:1, 1:1, 1:3 and 1:11) were manipulated across participants. The temporal discriminability of sources, measured by the ratio, was indeed a strong predictor of suggestibility. Most importantly, if the ratio was constant (e.g. 18/6 versus 9/3 days), performance was remarkably similar despite variations in absolute delay (e.g. 24 versus 12 days). This intriguing finding not only extends the ratio-rule of distinctiveness to misinformation paradigms, but also serves to illustrate a new empirical means of differentiating between explanations of suggestibility based on interference between sources and disintegration of source information over time.

Infant speech-sound discrimination testing: effects of stimulus intensity and procedural model on measures of performance.

PubMed

Nozza, R J

1987-06-01

Performance of infants in a speech-sound discrimination task (/ba/ vs /da/) was measured at three stimulus intensity levels (50, 60, and 70 dB SPL) using the operant head-turn procedure. The procedure was modified so that data could be treated as though from a single-interval (yes-no) procedure, as is commonly done, as well as if from a sustained attention (vigilance) task. Discrimination performance changed significantly with increase in intensity, suggesting caution in the interpretation of results from infant discrimination studies in which only single stimulus intensity levels within this range are used. The assumptions made about the underlying methodological model did not change the performance-intensity relationships. However, infants demonstrated response decrement, typical of vigilance tasks, which supports the notion that the head-turn procedure is represented best by the vigilance model. Analysis then was done according to a method designed for tasks with undefined observation intervals [C. S. Watson and T. L. Nichols, J. Acoust. Soc. Am. 59, 655-668 (1976)]. Results reveal that, while group data are reasonably well represented across levels of difficulty by the fixed-interval model, there is a variation in performance as a function of time following trial onset that could lead to underestimation of performance in some cases.

Discrimination surfaces with application to region-specific brain asymmetry analysis.

PubMed

Martos, Gabriel; de Carvalho, Miguel

2018-05-20

Discrimination surfaces are here introduced as a diagnostic tool for localizing brain regions where discrimination between diseased and nondiseased participants is higher. To estimate discrimination surfaces, we introduce a Mann-Whitney type of statistic for random fields and present large-sample results characterizing its asymptotic behavior. Simulation results demonstrate that our estimator accurately recovers the true surface and corresponding interval of maximal discrimination. The empirical analysis suggests that in the anterior region of the brain, schizophrenic patients tend to present lower local asymmetry scores in comparison with participants in the control group. Copyright © 2018 John Wiley & Sons, Ltd.

Electronic circuit delivers pulse of high interval stability

NASA Technical Reports Server (NTRS)

Fisher, B.

1966-01-01

Circuit generates a pulse of high interval stability with a complexity level considerably below systems of comparable stability. This circuit is being used as a linear frequency discriminator in the signal conditioner of the Apollo command module.

Optical timing receiver for the NASA laser ranging system. Part 2: High precision time interval digitizer

NASA Technical Reports Server (NTRS)

Leskovar, B.; Turko, B.

1977-01-01

The development of a high precision time interval digitizer is described. The time digitizer is a 10 psec resolution stop watch covering a range of up to 340 msec. The measured time interval is determined as a separation between leading edges of a pair of pulses applied externally to the start input and the stop input of the digitizer. Employing an interpolation techniques and a 50 MHz high precision master oscillator, the equivalent of a 100 GHz clock frequency standard is achieved. Absolute accuracy and stability of the digitizer are determined by the external 50 MHz master oscillator, which serves as a standard time marker. The start and stop pulses are fast 1 nsec rise time signals, according to the Nuclear Instrument means of tunnel diode discriminators. Firing level of the discriminator define start and stop points between which the time interval is digitized.

Different target-discrimination times can be followed by the same saccade-initiation timing in different stimulus conditions during visual searches

PubMed Central

Tanaka, Tomohiro; Nishida, Satoshi

2015-01-01

The neuronal processes that underlie visual searches can be divided into two stages: target discrimination and saccade preparation/generation. This predicts that the length of time of the prediscrimination stage varies according to the search difficulty across different stimulus conditions, whereas the length of the latter postdiscrimination stage is stimulus invariant. However, recent studies have suggested that the length of the postdiscrimination interval changes with different stimulus conditions. To address whether and how the visual stimulus affects determination of the postdiscrimination interval, we recorded single-neuron activity in the lateral intraparietal area (LIP) when monkeys (Macaca fuscata) performed a color-singleton search involving four stimulus conditions that differed regarding luminance (Bright vs. Dim) and target-distractor color similarity (Easy vs. Difficult). We specifically focused on comparing activities between the Bright-Difficult and Dim-Easy conditions, in which the visual stimuli were considerably different, but the mean reaction times were indistinguishable. This allowed us to examine the neuronal activity when the difference in the degree of search speed between different stimulus conditions was minimal. We found that not only prediscrimination but also postdiscrimination intervals varied across stimulus conditions: the postdiscrimination interval was longer in the Dim-Easy condition than in the Bright-Difficult condition. Further analysis revealed that the postdiscrimination interval might vary with stimulus luminance. A computer simulation using an accumulation-to-threshold model suggested that the luminance-related difference in visual response strength at discrimination time could be the cause of different postdiscrimination intervals. PMID:25995344

Second-order schedules: discrimination of components1

PubMed Central

Squires, Nancy; Norborg, James; Fantino, Edmund

1975-01-01

Pigeons were exposed to a series of second-order schedules in which the completion of a fixed number of fixed-interval components produced food. In Experiment 1, brief (2 sec) stimulus presentations occurred as each fixed-interval component was completed. During the brief-stimulus presentation terminating the last fixed-interval component, a response was required on a second key, the brief-stimulus key, to produce food. Responses on the brief-stimulus key before the last brief-stimulus presentation had no scheduled consequences, but served as a measure of the extent to which the final component was discriminated from preceding components. Whether there were one, two, four, or eight fixed-interval components, responses on the brief-stimulus key occurred during virtually every brief-stimulus presentation. In Experiment 2, an attempt was made to punish unnecessary responses on the brief-stimulus key, i.e., responses on the brief-stimulus key that occurred before the last component. None of the pigeons learned to withhold these responses, even though they produced a 15-sec timeout and loss of primary reinforcement. In Experiment 3, different key colors were associated with each component of a second-order schedule (a chain schedule). In contrast to Experiment 1, brief-stimulus key responses were confined to the last component. It was concluded that pigeons do not discriminate well between components of second-order schedules unless a unique exteroceptive cue is provided for each component. The relative discriminability of the components may account for the observed differences in initial-component response rates between comparable brief-stimulus, tandem, and chain schedules. PMID:16811868

Cognitive aspects of haptic form recognition by blind and sighted subjects.

PubMed

Bailes, S M; Lambert, R M

1986-11-01

Studies using haptic form recognition tasks have generally concluded that the adventitiously blind perform better than the congenitally blind, implicating the importance of early visual experience in improved spatial functioning. The hypothesis was tested that the adventitiously blind have retained some ability to encode successive information obtained haptically in terms of a global visual representation, while the congenitally blind use a coding system based on successive inputs. Eighteen blind (adventitiously and congenitally) and 18 sighted (blindfolded and performing with vision) subjects were tested on their recognition of raised line patterns when the standard was presented in segments: in immediate succession, or with unfilled intersegmental delays of 5, 10, or 15 seconds. The results did not support the above hypothesis. Three main findings were obtained: normally sighted subjects were both faster and more accurate than the other groups; all groups improved in accuracy of recognition as a function of length of interstimulus interval; sighted subjects tended to report using strategies with a strong verbal component while the blind tended to rely on imagery coding. These results are explained in terms of information-processing theory consistent with dual encoding systems in working memory.

Modulations of the processing of line discontinuities under selective attention conditions?

PubMed

Giersch, Anne; Fahle, Manfred

2002-01-01

We examined whether the processing of discontinuities involved in figure-ground segmentation, like line ends, can be modulated under selective attention conditions. Subjects decided whether a gap in collinear or parallel lines was located to the right or left. Two stimuli were displayed in immediate succession. When the gaps were on the same side, reaction times (RTs) for the second stimulus increased when collinear lines followed parallel lines, or the reverse, but only when the two stimuli shared the same orientation and location. The effect did not depend on the global form of the stimuli or on the relative orientation of the gaps. A frame drawn around collinear elements affected the results, suggesting a crucial role of the "amodal" orthogonal lines produced when line ends are aligned. Including several gaps in the first stimulus also eliminated RT variations. By contrast, RT variations remained stable across several experimental blocks and were significant for interstimulus intervals from 50 to 600 msec between the two stimuli. These results are interpreted in terms of a modulation of the processing of line ends or the production of amodal lines, arising when attention is selectively drawn to a gap.

Reactive and anticipatory looking in 6-month-old infants during a visual expectation paradigm.

PubMed

Quan, Jeffry; Bureau, Jean-François; Abdul Malik, Adam B; Wong, Johnny; Rifkin-Graboi, Anne

2017-10-01

This article presents data from 278 six-month-old infants who completed a visual expectation paradigm in which audiovisual stimuli were first presented randomly (random phase), and then in a spatial pattern (pattern phase). Infants' eye gaze behaviour was tracked with a 60 Hz Tobii eye-tracker in order to measure two types of looking behaviour: reactive looking (i.e., latency to shift eye gaze in reaction to the appearance of stimuli) and anticipatory looking (i.e., percentage of time spent looking at the location where the next stimulus is about to appear during the inter-stimulus interval). Data pertaining to missing data and task order effects are presented. Further analyses show that infants' reactive looking was faster in the pattern phase, compared to the random phase, and their anticipatory looking increased from random to pattern phases. Within the pattern phase, infants' reactive looking showed a quadratic trend, with reactive looking time latencies peaking in the middle portion of the phase. Similarly, within the pattern phase, infants' anticipatory looking also showed a quadratic trend, with anticipatory looking peaking during the middle portion of the phase.

Corticospinal activation confounds cerebellar effects of posterior fossa stimuli.

PubMed

Fisher, Karen M; Lai, H Ming; Baker, Mark R; Baker, Stuart N

2009-12-01

To investigate the efficacy of magnetic stimulation over the posterior fossa (PF) as a non-invasive assessment of cerebellar function in man. We replicated a previously reported conditioning-test paradigm in 11 healthy subjects. Transcranial magnetic stimulation (TMS) at varying intensities was applied to the PF and motor cortex with a 3, 5 or 7 ms interstimulus interval (ISI), chosen randomly for each trial. Surface electromyogram (EMG) activity was recorded from two intrinsic hand muscles and two forearm muscles. Responses were averaged and rectified, and MEP amplitudes were compared to assess whether suppression of the motor output occurred as a result of the PF conditioning pulse. Cortical MEPs were suppressed following conditioning-test ISIs of 5 or 7 ms. No suppression occurred with an ISI of 3 ms. PF stimuli alone also produced EMG responses, suggesting direct activation of the corticospinal tract (CST). CST collaterals are known to contact cortical inhibitory interneurones; antidromic CST activation could therefore contribute to the observed suppression of cortical MEPs. PF stimulation probably activates multiple pathways; even at low intensities it should not be regarded as a selective assessment of cerebellar function unless stringent controls can confirm the absence of confounding activity in other pathways.

Masked Priming Effects in Aphasia: Evidence for Altered Automatic Spreading Activation

PubMed Central

Silkes, JoAnn P.; Rogers, Margaret A.

2015-01-01

Purpose Previous research has suggested that impairments of automatic spreading activation may underlie some aphasic language deficits. This study further investigated the status of automatic spreading activation in individuals with aphasia as compared with typical adults. Method Participants were 21 individuals with aphasia (12 fluent, 9 non-fluent) and 31 typical adults. Reaction time data were collected on a lexical decision task with masked repetition primes, assessed at 11 different interstimulus intervals (ISIs). Masked primes were used to assess automatic spreading activation without the confound of conscious processing. The various ISIs were used to assess the time to onset, and duration, of priming effects. Results The control group showed maximal priming in the 200 ms ISI condition, with significant priming at a range of ISIs surrounding that peak. Participants with both fluent and non-fluent aphasia showed maximal priming effects in the 250 ms ISI condition, and primed across a smaller range of ISIs than the control group. Conclusions Results suggest that individuals with aphasia have slowed automatic spreading activation, and impaired maintenance of activation over time, regardless of fluency classification. These findings have implications for understanding aphasic language impairment and for development of aphasia treatments designed directly address automatic language processes. PMID:22411281

Masked priming effects in aphasia: evidence of altered automatic spreading activation.

PubMed

Silkes, JoAnn P; Rogers, Margaret A

2012-12-01

Previous research has suggested that impairments of automatic spreading activation may underlie some aphasic language deficits. The current study further investigated the status of automatic spreading activation in individuals with aphasia as compared with typical adults. Participants were 21 individuals with aphasia (12 fluent, 9 nonfluent) and 31 typical adults. Reaction time data were collected on a lexical decision task with masked repetition primes, assessed at 11 different interstimulus intervals (ISIs). Masked primes were used to assess automatic spreading activation without the confound of conscious processing. The various ISIs were used to assess the time to onset and duration of priming effects. The control group showed maximal priming in the 200-ms ISI condition, with significant priming at a range of ISIs surrounding that peak. Participants with both fluent and nonfluent aphasia showed maximal priming effects in the 250-ms ISI condition and primed across a smaller range of ISIs than did the control group. Results suggest that individuals with aphasia have slowed automatic spreading activation and impaired maintenance of activation over time, regardless of fluency classification. These findings have implications for understanding aphasic language impairment and for development of aphasia treatments designed to directly address automatic language processes.

Saliency predicts change detection in pictures of natural scenes.

PubMed

Wright, Michael J

2005-01-01

It has been proposed that the visual system encodes the salience of objects in the visual field in an explicit two-dimensional map that guides visual selective attention. Experiments were conducted to determine whether salience measurements applied to regions of pictures of outdoor scenes could predict the detection of changes in those regions. To obtain a quantitative measure of change detection, observers located changes in pairs of colour pictures presented across an interstimulus interval (ISI). Salience measurements were then obtained from different observers for image change regions using three independent methods, and all were positively correlated with change detection. Factor analysis extracted a single saliency factor that accounted for 62% of the variance contained in the four measures. Finally, estimates of the magnitude of the image change in each picture pair were obtained, using nine separate visual filters representing low-level vision features (luminance, colour, spatial frequency, orientation, edge density). None of the feature outputs was significantly associated with change detection or saliency. On the other hand it was shown that high-level (structural) properties of the changed region were related to saliency and to change detection: objects were more salient than shadows and more detectable when changed.

A compact electroencephalogram recording device with integrated audio stimulation system.

PubMed

Paukkunen, Antti K O; Kurttio, Anttu A; Leminen, Miika M; Sepponen, Raimo E

2010-06-01

A compact (96 x 128 x 32 mm(3), 374 g), battery-powered, eight-channel electroencephalogram recording device with an integrated audio stimulation system and a wireless interface is presented. The recording device is capable of producing high-quality data, while the operating time is also reasonable for evoked potential studies. The effective measurement resolution is about 4 nV at 200 Hz sample rate, typical noise level is below 0.7 microV(rms) at 0.16-70 Hz, and the estimated operating time is 1.5 h. An embedded audio decoder circuit reads and plays wave sound files stored on a memory card. The activities are controlled by an 8 bit main control unit which allows accurate timing of the stimuli. The interstimulus interval jitter measured is less than 1 ms. Wireless communication is made through bluetooth and the data recorded are transmitted to an external personal computer (PC) interface in real time. The PC interface is implemented with LABVIEW and in addition to data acquisition it also allows online signal processing, data storage, and control of measurement activities such as contact impedance measurement, for example. The practical application of the device is demonstrated in mismatch negativity experiment with three test subjects.

A compact electroencephalogram recording device with integrated audio stimulation system

NASA Astrophysics Data System (ADS)

Paukkunen, Antti K. O.; Kurttio, Anttu A.; Leminen, Miika M.; Sepponen, Raimo E.

2010-06-01

A compact (96×128×32 mm3, 374 g), battery-powered, eight-channel electroencephalogram recording device with an integrated audio stimulation system and a wireless interface is presented. The recording device is capable of producing high-quality data, while the operating time is also reasonable for evoked potential studies. The effective measurement resolution is about 4 nV at 200 Hz sample rate, typical noise level is below 0.7 μVrms at 0.16-70 Hz, and the estimated operating time is 1.5 h. An embedded audio decoder circuit reads and plays wave sound files stored on a memory card. The activities are controlled by an 8 bit main control unit which allows accurate timing of the stimuli. The interstimulus interval jitter measured is less than 1 ms. Wireless communication is made through bluetooth and the data recorded are transmitted to an external personal computer (PC) interface in real time. The PC interface is implemented with LABVIEW® and in addition to data acquisition it also allows online signal processing, data storage, and control of measurement activities such as contact impedance measurement, for example. The practical application of the device is demonstrated in mismatch negativity experiment with three test subjects.

Temporal orienting precedes intersensory attention and has opposing effects on early evoked brain activity.

PubMed

Keil, Julian; Pomper, Ulrich; Feuerbach, Nele; Senkowski, Daniel

2017-03-01

Intersensory attention (IA) describes the process of directing attention to a specific modality. Temporal orienting (TO) characterizes directing attention to a specific moment in time. Previously, studies indicated that these two processes could have opposite effects on early evoked brain activity. The exact time-course and processing stages of both processes are still unknown. In this human electroencephalography study, we investigated the effects of IA and TO on visuo-tactile stimulus processing within one paradigm. IA was manipulated by presenting auditory cues to indicate whether participants should detect visual or tactile targets in visuo-tactile stimuli. TO was manipulated by presenting stimuli block-wise at fixed or variable inter-stimulus intervals. We observed that TO affects evoked activity to visuo-tactile stimuli prior to IA. Moreover, we found that TO reduces the amplitude of early evoked brain activity, whereas IA enhances it. Using beamformer source-localization, we observed that IA increases neural responses in sensory areas of the attended modality whereas TO reduces brain activity in widespread cortical areas. Based on these findings we derive an updated working model for the effects of temporal and intersensory attention on early evoked brain activity. Copyright © 2017 Elsevier Inc. All rights reserved.

DISCRIMINATION ACQUISITION IN CHILDREN WITH DEVELOPMENTAL DISABILITIES UNDER IMMEDIATE AND DELAYED REINFORCEMENT

PubMed Central

Sy, Jolene R.; Vollmer, Timothy R.

2012-01-01

We evaluated the discrimination acquisition of individuals with developmental disabilities under immediate and delayed reinforcement. In Experiment 1, discrimination between two alternatives was examined when reinforcement was immediate or delayed by 20 s, 30 s, or 40 s. In Experiment 2, discrimination between 2 alternatives was compared across an immediate reinforcement condition and a delayed reinforcement condition in which subjects could respond during the delay. In Experiment 3, discrimination among 4 alternatives was compared across immediate and delayed reinforcement. In Experiment 4, discrimination between 2 alternatives was examined when reinforcement was immediate and 0-s or 30-s intertrial intervals (ITI) were programmed. For most subjects, discrimination acquisition occurred under immediate reinforcement. However, for some subjects, introducing delays slowed or prevented discrimination acquisition under some conditions. Results from Experiment 4 suggest that longer ITIs cannot account for the lack of discrimination under delayed reinforcement. PMID:23322925

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.

Sex Differences in the Generalization of Fear as a Function of Retention Intervals

ERIC Educational Resources Information Center

Lynch, Joseph, III; Cullen, Patrick K.; Jasnow, Aaron M.; Riccio, David C.

2013-01-01

In previous studies using male rodents, context change disrupted a fear response at a short, but not a long, retention interval. Here, we examined the effects of context changes on fear responses as a function of time in male and female rats. Males displayed context discrimination at all intervals, whereas females exhibited generalization by 5 d.…

Method of high precision interval measurement in pulse laser ranging system

NASA Astrophysics Data System (ADS)

Wang, Zhen; Lv, Xin-yuan; Mao, Jin-jin; Liu, Wei; Yang, Dong

2013-09-01

Laser ranging is suitable for laser system, for it has the advantage of high measuring precision, fast measuring speed,no cooperative targets and strong resistance to electromagnetic interference,the measuremen of laser ranging is the key paremeters affecting the performance of the whole system.The precision of the pulsed laser ranging system was decided by the precision of the time interval measurement, the principle structure of laser ranging system was introduced, and a method of high precision time interval measurement in pulse laser ranging system was established in this paper.Based on the analysis of the factors which affected the precision of range measure,the pulse rising edges discriminator was adopted to produce timing mark for the start-stop time discrimination,and the TDC-GP2 high precision interval measurement system based on TMS320F2812 DSP was designed to improve the measurement precision.Experimental results indicate that the time interval measurement method in this paper can obtain higher range accuracy. Compared with the traditional time interval measurement system,the method simplifies the system design and reduce the influence of bad weather conditions,furthermore,it satisfies the requirements of low costs and miniaturization.

Associations Between Perceived Race-based Discrimination and Contraceptive Use Among Women Veterans in the ECUUN Study.

PubMed

MacDonald, Serena; Hausmann, Leslie R M; Sileanu, Florentina E; Zhao, Xinhua; Mor, Maria K; Borrero, Sonya

2017-09-01

To describe perceived race-based discrimination in Veterans Affairs (VA) health care settings and assess its associations with contraceptive use among a sample of women Veterans. This study used data from a national telephone survey of women Veterans aged 18-44 receiving health care in VA who were at risk of unintended pregnancy. Participants were asked about their perceptions of race-based discrimination while seeking VA health care and about their contraceptive use at last heterosexual intercourse. Logistic and multinomial regression analyses were used to examine associations between perceived race-based discrimination with use of prescription contraception. In our sample of 1341 women Veterans, 7.9% report perceived race-based discrimination when receiving VA care, with blacks and Hispanics reporting higher levels of perceived discrimination than white women (11.3% and 11.2% vs. 4.4%; P<0.001). In logistic and multinomial regression analyses adjusting for race/ethnicity, age, income, marital status, parity, and insurance, women who perceived race-based discrimination were less likely to use any prescription birth control than women who did not (odds ratio, 0.65; 95% confidence interval, 0.42-1.00), with the largest difference seen in rates of intrauterine device or implant use (odds ratio, 0.40; 95% confidence interval, 0.20-0.79). In this national sample of women Veterans, over 10% of racial/ethnic minority women perceived race-based discrimination when receiving care in VA settings, and perceived racial/ethnic discrimination was associated with lower likelihood of prescription contraception use, especially intrauterine devices and implants. VA efforts to enhance respectful interactions may not only improve patient health care experiences, but also represent an opportunity to improve reproductive health outcomes for women Veterans.

Perceived Discrimination and Hypertension Among African Americans in the Jackson Heart Study

PubMed Central

Sims, Mario; Diez-Roux, Ana V.; Dudley, Amanda; Gebreab, Samson; Wyatt, Sharon B.; Bruce, Marino A.; James, Sherman A.; Robinson, Jennifer C.; Williams, David R.; Taylor, Herman A.

2012-01-01

Objectives. Using Jackson Heart Study data, we examined whether perceived discrimination was associated with prevalent hypertension in African Americans. Methods. Everyday discrimination, lifetime discrimination, burden of discrimination, and stress from discrimination were examined among 4939 participants aged 35 to 84 years (women = 3123; men = 1816). We estimated prevalence ratios of hypertension by discrimination, and adjusted for age, gender, socioeconomic status, and risk factors. Results. The prevalence of hypertension was 64.0% in women and 59.7% in men. After adjustment for age, gender, and socioeconomic status, lifetime discrimination and burden of discrimination were associated with greater hypertension prevalence (prevalence ratios for highest vs lowest quartile were 1.08 [95% confidence interval (CI) = 1.02, 1.15] and 1.09 [95% CI = 1.02,1.16] for lifetime discrimination and burden of discrimination, respectively). Associations were slightly weakened after adjustment for body mass index and behavioral factors. No associations were observed for everyday discrimination. Conclusions. Further understanding the role of perceived discrimination in the etiology of hypertension may be beneficial in eliminating hypertension disparities. PMID:22401510

Perceived discrimination and hypertension among African Americans in the Jackson Heart Study.

PubMed

Sims, Mario; Diez-Roux, Ana V; Dudley, Amanda; Gebreab, Samson; Wyatt, Sharon B; Bruce, Marino A; James, Sherman A; Robinson, Jennifer C; Williams, David R; Taylor, Herman A

2012-05-01

Using Jackson Heart Study data, we examined whether perceived discrimination was associated with prevalent hypertension in African Americans. Everyday discrimination, lifetime discrimination, burden of discrimination, and stress from discrimination were examined among 4939 participants aged 35 to 84 years (women = 3123; men = 1816). We estimated prevalence ratios of hypertension by discrimination, and adjusted for age, gender, socioeconomic status, and risk factors. The prevalence of hypertension was 64.0% in women and 59.7% in men. After adjustment for age, gender, and socioeconomic status, lifetime discrimination and burden of discrimination were associated with greater hypertension prevalence (prevalence ratios for highest vs lowest quartile were 1.08 [95% confidence interval (CI) = 1.02, 1.15] and 1.09 [95% CI = 1.02,1.16] for lifetime discrimination and burden of discrimination, respectively). Associations were slightly weakened after adjustment for body mass index and behavioral factors. No associations were observed for everyday discrimination. Further understanding the role of perceived discrimination in the etiology of hypertension may be beneficial in eliminating hypertension disparities.

Double Dissociation of Pharmacologically Induced Deficits in Visual Recognition and Visual Discrimination Learning

ERIC Educational Resources Information Center

Turchi, Janita; Buffalari, Deanne; Mishkin, Mortimer

2008-01-01

Monkeys trained in either one-trial recognition at 8- to 10-min delays or multi-trial discrimination habits with 24-h intertrial intervals received systemic cholinergic and dopaminergic antagonists, scopolamine and haloperidol, respectively, in separate sessions. Recognition memory was impaired markedly by scopolamine but not at all by…

Transformation of temporal sequences in the zebra finch auditory system

PubMed Central

Lim, Yoonseob; Lagoy, Ryan; Shinn-Cunningham, Barbara G; Gardner, Timothy J

2016-01-01

This study examines how temporally patterned stimuli are transformed as they propagate from primary to secondary zones in the thalamorecipient auditory pallium in zebra finches. Using a new class of synthetic click stimuli, we find a robust mapping from temporal sequences in the primary zone to distinct population vectors in secondary auditory areas. We tested whether songbirds could discriminate synthetic click sequences in an operant setup and found that a robust behavioral discrimination is present for click sequences composed of intervals ranging from 11 ms to 40 ms, but breaks down for stimuli composed of longer inter-click intervals. This work suggests that the analog of the songbird auditory cortex transforms temporal patterns to sequence-selective population responses or ‘spatial codes', and that these distinct population responses contribute to behavioral discrimination of temporally complex sounds. DOI: http://dx.doi.org/10.7554/eLife.18205.001 PMID:27897971

Disrupted sensory gating in pathological gambling.

PubMed

Stojanov, Wendy; Karayanidis, Frini; Johnston, Patrick; Bailey, Andrew; Carr, Vaughan; Schall, Ulrich

2003-08-15

Some neurochemical evidence as well as recent studies on molecular genetics suggest that pathologic gambling may be related to dysregulated dopamine neurotransmission. The current study examined sensory (motor) gating in pathologic gamblers as a putative measure of endogenous brain dopamine activity with prepulse inhibition of the acoustic startle eye-blink response and the auditory P300 event-related potential. Seventeen pathologic gamblers and 21 age- and gender-matched healthy control subjects were assessed. Both prepulse inhibition measures were recorded under passive listening and two-tone prepulse discrimination conditions. Compared to the control group, pathologic gamblers exhibited disrupted sensory (motor) gating on all measures of prepulse inhibition. Sensory motor gating deficits of eye-blink responses were most profound at 120-millisecond prepulse lead intervals in the passive listening task and at 240-millisecond prepulse lead intervals in the two-tone prepulse discrimination task. Sensory gating of P300 was also impaired in pathologic gamblers, particularly at 500-millisecond lead intervals, when performing the discrimination task on the prepulse. In the context of preclinical studies on the disruptive effects of dopamine agonists on prepulse inhibition, our findings suggest increased endogenous brain dopamine activity in pathologic gambling in line with previous neurobiological findings.

Can Inexperienced Listeners Hear Who Is Singing? The Role of Onset Cues.

PubMed

Erickson, Molly L

2018-05-28

This study sought to determine whether the acoustic information contained in the onset of phonation can improve the ability to discriminate voices across pitch. This study was a repeated-measures factorial design. Listeners heard two singers producing /ɑ/ at the same pitch and an unknown singer producing /ɑ/ at a different pitch. Listener's identified which singer was the unknown singer. Two baritones and two tenors were recorded producing /ɑ/ at the pitches C3, E3, G3, B3, D4, and F4. Two sopranos and two mezzo-sopranos were recorded producing /ɑ/ at the pitches C4, E4, G4, B4, D5, and F5. For each group of stimuli, male and female, all possible pairs of singers were constructed for the lowest pitch. The unknown singer was varied across the remaining pitches. All stimulus combinations were presented with and without onset cues. In general, the inclusion of onset information affected listeners' ability to discriminate singers across pitch. When the pitch interval was small, a 3rd or a 5th, onset information improved the ability to correctly discriminate singers across pitch. This effect was greater for female voices than for male voices. However, when the pitch interval was larger, a 7th, 9th, or 11th, the onset information either had no effect, as was seen in the female voices, or had a negative effect, as was seen in the male voices. Voice onset information affects voice discrimination in certain circumstances, but cannot be used by inexperienced listeners as a consistent cue to improve singer discrimination across all pitch intervals. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Plasma-laser ion discrimination by TOF technique applied to coupled SiC detectors.

NASA Astrophysics Data System (ADS)

Cavallaro, Salvatore

2018-01-01

The rate estimation of nuclear reactions induced in high intensity laser-target interaction (≥1016 W/cm2), is strongly depending on the neutron detection efficiency and ion charge discrimination, according to particles involved in exit open-channels. Ion discrimination is basically performed by means of analysis of pits observed on track detector, which is critically dependent on calibration and/or fast TOF devices based on SiC and diamond detectors. Last setup is used to determine the ion energy and to obtain a rough estimation of yields. However, for each TOF interval, the dependence of yield from the energy deposited in the detector sensitive region, introduces a distortion in the ion spectra. Moreover, if two ion species are present in the same spectrum, the discrimination of their contribution is not attainable. In this paper a new method is described which allows to discriminate the contribution of two ion species in the wide energy range of nuclear reactions induced in laser-target interactions. The method is based on charge response of two TOF-SiC detectors, of suitable thicknesses, placed in adjacent positions. In presence of two ion species, the response of the detectors, associated with different energy losses, can determine the ion specific contribution to each TOF interval.

Auditory Memory Decay as Reflected by a New Mismatch Negativity Score Is Associated with Episodic Memory in Older Adults at Risk of Dementia

PubMed Central

Laptinskaya, Daria; Thurm, Franka; Küster, Olivia C.; Fissler, Patrick; Schlee, Winfried; Kolassa, Stephan; von Arnim, Christine A. F.; Kolassa, Iris-Tatjana

2018-01-01

The auditory mismatch negativity (MMN) is an event-related potential (ERP) peaking about 100–250 ms after the onset of a deviant tone in a sequence of identical (standard) tones. Depending on the interstimulus interval (ISI) between standard and deviant tones, the MMN is suitable to investigate the pre-attentive auditory discrimination ability (short ISIs, ≤ 2 s) as well as the pre-attentive auditory memory trace (long ISIs, >2 s). However, current results regarding the MMN as an index for mild cognitive impairment (MCI) and dementia are mixed, especially after short ISIs: while the majority of studies report positive associations between the MMN and cognition, others fail to find such relationships. To elucidate these so far inconsistent results, we investigated the validity of the MMN as an index for cognitive impairment exploring the associations between different MMN indices and cognitive performance, more specifically with episodic memory performance which is among the most affected cognitive domains in the course of Alzheimer’s dementia (AD), at baseline and at a 5-year-follow-up. We assessed the amplitude of the MMN for short ISI (stimulus onset asynchrony, SOA = 0.05 s) and for long ISI (3 s) in a neuropsychologically well-characterized cohort of older adults at risk of dementia (subjective memory impairment, amnestic and non-amnestic MCI; n = 57). Furthermore, we created a novel difference score (ΔMMN), defined as the difference between MMNs to short and to long ISI, as a measure to assess the decay of the auditory memory trace, higher values indicating less decay. ΔMMN and MMN amplitude after long ISI, but not the MMN amplitude after short ISI, was associated with episodic memory at baseline (β = 0.38, p = 0.003; β = −0.27, p = 0.047, respectively). ΔMMN, but not the MMN for long ISIs, was positively associated with episodic memory performance at the 5-year-follow-up (β = 0.57, p = 0.013). The results suggest that the MMN after long ISI might be suitable as an indicator for the decline in episodic memory and indicate ΔMMN as a potential biomarker for memory impairment in older adults at risk of dementia. PMID:29456500

The truth will out: interrogative polygraphy ("lie detection") with event-related brain potentials.

PubMed

Farwell, L A; Donchin, E

1991-09-01

The feasibility of using Event Related Brain Potentials (ERPs) in Interrogative Polygraphy ("Lie Detection") was tested by examining the effectiveness of the Guilty Knowledge Test designed by Farwell and Donchin (1986, 1988). The subject is assigned an arbitrary task requiring discrimination between experimenter-designated targets and other, irrelevant stimuli. A group of diagnostic items ("probes"), which to the unwitting are indistinguishable from the irrelevant items, are embedded among the irrelevant. For subjects who possess "guilty knowledge" these probes are distinct from the irrelevants and are likely to elicit a P300, thus revealing their possessing the special knowledge that allows them to differentiate the probes from the irrelevants. We report two experiments in which this paradigm was tested. In Experiment 1, 20 subjects participated in one of two mock espionage scenarios and were tested for their knowledge of both scenarios. All stimuli consisted of short phrases presented for 300 ms each at an interstimulus interval of 1550 ms. A set of items were designated as "targets" and appeared on 17% of the trials. Probes related to the scenarios also appeared on 17% of the trials. The rest of the items were irrelevants. Subjects responded by pressing one switch following targets, and the other following irrelevants (and, of course, probes). ERPs were recorded from FZ, CZ, and PZ. As predicted, targets elicited large P300s in all subjects. Probes associated with a given scenario elicited a P300 in subjects who participated in that scenario. A bootstrapping method was used to assess the quality of the decision for each subject. The algorithm declared the decision indeterminate in 12.5% of the cases. In all other cases a decision was made. There were no false positives and no false negatives: whenever a determination was made it was accurate. The second experiment was virtually identical to the first, with identical results, except that this time 4 subjects were tested, each of which had a minor brush with the law. Subjects were tested to determine whether they possessed information on their own "crimes." The results were as expected; the Guilty Knowledge Test determined correctly which subject possessed which information. The implications of these data both for the practice of Interrogative Polygraphy and the interpretation of the P300 are discussed.

Auditory Memory Decay as Reflected by a New Mismatch Negativity Score Is Associated with Episodic Memory in Older Adults at Risk of Dementia.

PubMed

Laptinskaya, Daria; Thurm, Franka; Küster, Olivia C; Fissler, Patrick; Schlee, Winfried; Kolassa, Stephan; von Arnim, Christine A F; Kolassa, Iris-Tatjana

2018-01-01

The auditory mismatch negativity (MMN) is an event-related potential (ERP) peaking about 100-250 ms after the onset of a deviant tone in a sequence of identical (standard) tones. Depending on the interstimulus interval (ISI) between standard and deviant tones, the MMN is suitable to investigate the pre-attentive auditory discrimination ability (short ISIs, ≤ 2 s) as well as the pre-attentive auditory memory trace (long ISIs, >2 s). However, current results regarding the MMN as an index for mild cognitive impairment (MCI) and dementia are mixed, especially after short ISIs: while the majority of studies report positive associations between the MMN and cognition, others fail to find such relationships. To elucidate these so far inconsistent results, we investigated the validity of the MMN as an index for cognitive impairment exploring the associations between different MMN indices and cognitive performance, more specifically with episodic memory performance which is among the most affected cognitive domains in the course of Alzheimer's dementia (AD), at baseline and at a 5-year-follow-up. We assessed the amplitude of the MMN for short ISI (stimulus onset asynchrony, SOA = 0.05 s) and for long ISI (3 s) in a neuropsychologically well-characterized cohort of older adults at risk of dementia (subjective memory impairment, amnestic and non-amnestic MCI; n = 57). Furthermore, we created a novel difference score (ΔMMN), defined as the difference between MMNs to short and to long ISI, as a measure to assess the decay of the auditory memory trace, higher values indicating less decay. ΔMMN and MMN amplitude after long ISI, but not the MMN amplitude after short ISI, was associated with episodic memory at baseline ( β = 0.38, p = 0.003; β = -0.27, p = 0.047, respectively). ΔMMN, but not the MMN for long ISIs, was positively associated with episodic memory performance at the 5-year-follow-up ( β = 0.57, p = 0.013). The results suggest that the MMN after long ISI might be suitable as an indicator for the decline in episodic memory and indicate ΔMMN as a potential biomarker for memory impairment in older adults at risk of dementia.

d'plus: A program to calculate accuracy and bias measures from detection and discrimination data.

PubMed

Macmillan, N A; Creelman, C D

1997-01-01

The program d'plus calculates accuracy (sensitivity) and response-bias parameters using Signal Detection Theory. Choice Theory, and 'nonparametric' models. is is appropriate for data from one-interval, two- and three-interval forced-choice, same different, ABX, and oddity experimental paradigms.

Pigeons' Memory for Number of Events: Effects of Intertrial Interval and Delay Interval Illumination

ERIC Educational Resources Information Center

Hope, Chris; Santi, Angelo

2004-01-01

In Experiment 1, pigeons were trained at a 0-s baseline delay to discriminate sequences of light flashes (illumination of the feeder) that varied in number but not time (2f/4s and 8f/4s). During training, the intertrial interval was illuminated by the houselight for Group Light, but it was dark for Group Dark. Testing conducted with dark delay…

The Longitudinal Associations Between Discrimination, Depressive Symptoms, and Prosocial Behaviors in U.S. Latino/a Recent Immigrant Adolescents.

PubMed

Davis, Alexandra N; Carlo, Gustavo; Schwartz, Seth J; Unger, Jennifer B; Zamboanga, Byron L; Lorenzo-Blanco, Elma I; Cano, Miguel Ángel; Baezconde-Garbanati, Lourdes; Oshri, Assaf; Streit, Cara; Martinez, Miriam M; Piña-Watson, Brandy; Lizzi, Karina; Soto, Daniel

2016-03-01

The links between discrimination and adjustment in U.S. Latino/a immigrant adolescents is an important but understudied phenomenon. We aimed to investigate the longitudinal associations (across 1 year) among discrimination, prosocial behaviors, and depressive symptoms in U.S. Latino immigrant adolescents using two competing models: associations between discrimination and prosocial behaviors via depressive symptoms (mental health strain model), and associations between discrimination and depressive symptoms via prosocial behaviors (prosociality strain model). Participants were 302 Latino/a recent immigrant adolescents (53.3 % boys, M age = 14.51 years at Time 1, SD = .88 years) who completed measures of discrimination, depressive symptoms, and prosocial behaviors at 6-month intervals. The results provided support for both proposed models. The discussion examines the importance of prosocial behaviors in understanding adjustment and effects of discrimination among recently immigrated U.S. Latino adolescents.

Scopolamine Impairs Appetitive But Not Aversive Trace Conditioning: Role of the Medial Prefrontal Cortex.

PubMed

Pezze, Marie-Astrid; Marshall, Hayley J; Cassaday, Helen J

2017-06-28

The muscarinic acetylcholine receptor is an important modulator of medial prefrontal cortex (mPFC) functions, such as the working memory required to bridge a trace interval in associative leaning. Aversive and appetitive trace conditioning procedures were used to examine the effects of scopolamine (0.1 and 0.5 mg/kg, i.p.) in male rats. Follow-up experiments tested the effects of microinfusion of 0.15 μg of scopolamine (0.075 μg of in 0.5 μl/side) in infralimbic (IL) versus prelimbic regions of rat mPFC, in appetitive trace and locomotor activity (LMA) procedures. Systemic scopolamine was without effect in an aversive trace conditioning procedure, but impaired appetitive conditioning at a 2 s trace interval. This effect was demonstrated as reduced responding during presentations of the conditioned stimulus (CS) and during the interstimulus interval (ISI). There was no such effect on responding during food (unconditioned stimulus, US) responding or in the intertrial interval (ITI). In contrast, systemic scopolamine dose-relatedly increased LMA. Trace conditioning was similarly impaired at the 2 s trace (shown as reduced responding to the CS and during the ISI, but not during US presentations or in the ITI) after infusion in mPFC, whereas LMA was increased (after infusion in IL only). Therefore, our results point to the importance of cholinergic modulation in mPFC for trace conditioning and show that the observed effects cannot be attributed to reduced activity. SIGNIFICANCE STATEMENT Events are very often separated in time, in which case working memory is necessary to condition their association in "trace conditioning." The present study used conditioning variants motivated aversively with foot shock and appetitively with food. The drug scopolamine was used to block muscarinic acetylcholine receptors involved in working memory. The results show that reduced cholinergic transmission in medial prefrontal cortex (mPFC) impaired appetitive trace conditioning at a 2 s trace interval. However, scopolamine was without effect in the aversive procedure, revealing the importance of procedural differences to the demonstration of the drug effect. The finding that blockade of muscarinic receptors in mPFC impaired trace conditioning shows that these receptors are critical modulators of short-term working memory. Copyright © 2017 Pezze et al.

Scopolamine Impairs Appetitive But Not Aversive Trace Conditioning: Role of the Medial Prefrontal Cortex

PubMed Central

Pezze, Marie-Astrid; Marshall, Hayley J.

2017-01-01

The muscarinic acetylcholine receptor is an important modulator of medial prefrontal cortex (mPFC) functions, such as the working memory required to bridge a trace interval in associative leaning. Aversive and appetitive trace conditioning procedures were used to examine the effects of scopolamine (0.1 and 0.5 mg/kg, i.p.) in male rats. Follow-up experiments tested the effects of microinfusion of 0.15 μg of scopolamine (0.075 μg of in 0.5 μl/side) in infralimbic (IL) versus prelimbic regions of rat mPFC, in appetitive trace and locomotor activity (LMA) procedures. Systemic scopolamine was without effect in an aversive trace conditioning procedure, but impaired appetitive conditioning at a 2 s trace interval. This effect was demonstrated as reduced responding during presentations of the conditioned stimulus (CS) and during the interstimulus interval (ISI). There was no such effect on responding during food (unconditioned stimulus, US) responding or in the intertrial interval (ITI). In contrast, systemic scopolamine dose-relatedly increased LMA. Trace conditioning was similarly impaired at the 2 s trace (shown as reduced responding to the CS and during the ISI, but not during US presentations or in the ITI) after infusion in mPFC, whereas LMA was increased (after infusion in IL only). Therefore, our results point to the importance of cholinergic modulation in mPFC for trace conditioning and show that the observed effects cannot be attributed to reduced activity. SIGNIFICANCE STATEMENT Events are very often separated in time, in which case working memory is necessary to condition their association in “trace conditioning.” The present study used conditioning variants motivated aversively with foot shock and appetitively with food. The drug scopolamine was used to block muscarinic acetylcholine receptors involved in working memory. The results show that reduced cholinergic transmission in medial prefrontal cortex (mPFC) impaired appetitive trace conditioning at a 2 s trace interval. However, scopolamine was without effect in the aversive procedure, revealing the importance of procedural differences to the demonstration of the drug effect. The finding that blockade of muscarinic receptors in mPFC impaired trace conditioning shows that these receptors are critical modulators of short-term working memory. PMID:28559376

Dimension-based attention in visual short-term memory.

PubMed

Pilling, Michael; Barrett, Doug J K

2016-07-01

We investigated how dimension-based attention influences visual short-term memory (VSTM). This was done through examining the effects of cueing a feature dimension in two perceptual comparison tasks (change detection and sameness detection). In both tasks, a memory array and a test array consisting of a number of colored shapes were presented successively, interleaved by a blank interstimulus interval (ISI). In Experiment 1 (change detection), the critical event was a feature change in one item across the memory and test arrays. In Experiment 2 (sameness detection), the critical event was the absence of a feature change in one item across the two arrays. Auditory cues indicated the feature dimension (color or shape) of the critical event with 80 % validity; the cues were presented either prior to the memory array, during the ISI, or simultaneously with the test array. In Experiment 1, the cue validity influenced sensitivity only when the cue was given at the earliest position; in Experiment 2, the cue validity influenced sensitivity at all three cue positions. We attributed the greater effectiveness of top-down guidance by cues in the sameness detection task to the more active nature of the comparison process required to detect sameness events (Hyun, Woodman, Vogel, Hollingworth, & Luck, Journal of Experimental Psychology: Human Perception and Performance, 35; 1140-1160, 2009).

Augmentation of the Sympathetic Skin Response after Electrical Train Stimuli

PubMed Central

Emmer, A.; Mangalo, S.; Kornhuber, M. E.

2012-01-01

It is well known that the size of the sympathetic skin response (SSR) depends on the stimulus strength. In the present investigation train stimuli (TS) were employed to study the behavior of the SSR when recruited above the usual level. The SSR was obtained in healthy human subjects over the palm of the hand after supramaximal single stimuli (SS) and trains of three (TS; interstimulus interval 3 ms) over the ipsilateral superficial radial nerve in 15 healthy volunteers. Ipsilateral to the stimulus site SSR amplitudes were 5.7 ± 5.3 (SS) and 7.7 ± 5.9 mV (TS; p < 0.001), and contralateral 6.3 ± 6.3 (SS) and 7.2 ± 4.9 mV (TS; not significant). The relative gain in amplitude after TS vs. SS was negatively correlated with the SSR amplitude after SS ipsilateral (p < 0.0005) and contralateral to the stimulus site (p < 0.01). The increase in SSR amplitudes after TS compared with SS is in line with temporal summation of the excitatory synaptic input in neurons generating the SSR. Driving the SSR with TS is of possible relevance for the investigation of disorders of the peripheral or central autonomic nervous system. PMID:23115555

Transcranial magnetic and electrical stimulation compared: does TES activate intracortical neuronal circuits?

PubMed

Brocke, J; Irlbacher, K; Hauptmann, B; Voss, M; Brandt, S A

2005-12-01

To determine whether, and under which conditions, transcranial electrical stimulation (TES) and transcranial magnetic stimulation (TMS) can activate similar neuronal structures of the human motor cortex, as indicated by electromyographic recordings. Focal TMS was performed on three subjects inducing a postero-anterior directed current (p-a), TES with postero-anteriorly (p-a) and latero-medially (l-m) oriented electrodes. We analyzed the onset latencies and amplitudes (single-pulse) and intracortical inhibition and excitation (paired-pulse). TMS p-a and TES p-a produced muscle responses with the same onset latency, while TES l-m led to 1.4-1.9 ms shorter latencies. Paired-pulse TMS p-a and TES p-a induced inhibition at short inter-stimulus intervals (ISI) (maximum: 2-3 ms) and facilitation at longer ISIs (maximum: 10 ms). No inhibition but a strong facilitation was obtained from paired-pulse TES l-m (ISIs 1-5 ms). Our findings support the hypothesis, that current direction is the most relevant factor in determining the mode of activation for both TMS and TES: TMS p-a and TES p-a are likely to activate the corticospinal neurons indirectly. In contrast, TES l-m may preferentially activate the corticospinal fibres directly, distant of the neuronal body. TES is a suitable tool to induce intracortical inhibition and excitation.

High-Fidelity Visual Long-Term Memory within an Unattended Blink of an Eye.

PubMed

Kuhbandner, Christof; Rosas-Corona, Elizabeth A; Spachtholz, Philipp

2017-01-01

What is stored in long-term memory from current sensations is a question that has attracted considerable interest. Over time, several prominent theories have consistently proposed that only attended sensory information leaves a durable memory trace whereas unattended information is not stored beyond the current moment, an assumption that seems to be supported by abundant empirical evidence. Here we show, by using a more sensitive memory test than in previous studies, that this is actually not true. Observers viewed a rapid stream of real-world object pictures overlapped by words (presentation duration per stimulus: 500 ms, interstimulus interval: 200 ms), with the instruction to attend to the words and detect word repetitions, without knowing that their memory would be tested later. In a surprise two-alternative forced-choice recognition test, memory for the unattended object pictures was tested. Memory performance was substantially above chance, even when detailed feature knowledge was necessary for correct recognition, even when tested 24 h later, and even although participants reported that they do not have any memories. These findings suggests that humans have the ability to store at high speed detailed copies of current visual stimulations in long-term memory independently of current intentions and the current attentional focus.

Cerebellar theta burst stimulation modulates short latency afferent inhibition in Alzheimer's disease patients

PubMed Central

Di Lorenzo, Francesco; Martorana, Alessandro; Ponzo, Viviana; Bonnì, Sonia; D'Angelo, Egidio; Caltagirone, Carlo; Koch, Giacomo

2013-01-01

The dysfunction of cholinergic neurons is a typical hallmark in Alzheimer's disease (AD). Previous findings demonstrated that high density of cholinergic receptors is found in the thalamus and the cerebellum compared with the cerebral cortex and the hippocampus. We aimed at investigating whether activation of the cerebello-thalamo-cortical pathway by means of cerebellar theta burst stimulation (TBS) could modulate central cholinergic functions evaluated in vivo by using the neurophysiological determination of Short-Latency Afferent Inhibition (SLAI). We tested the SLAI circuit before and after administration of cerebellar continuous TBS (cTBS) in 12 AD patients and in 12 healthy age-matched control subjects (HS). We also investigated potential changes of intracortical circuits of the contralateral primary motor cortex (M1) by assessing short intracortical inhibition (SICI) and intracortical facilitation (ICF). SLAI was decreased in AD patients compared to HS. Cerebellar cTBS partially restored SLAI in AD patients at later inter-stimulus intervals (ISIs), but did not modify SLAI in HS. SICI and ICF did not differ in the two groups and were not modulated by cerebellar cTBS. These results demonstrate that cerebellar magnetic stimulation is likely to affect mechanisms of cortical cholinergic activity, suggesting that the cerebellum may have a direct influence on the cholinergic dysfunction in AD. PMID:23423358

Integrating TRPV1 Receptor Function with Capsaicin Psychophysics

PubMed Central

Smutzer, Gregory; Devassy, Roni K.

2016-01-01

Capsaicin is a naturally occurring vanilloid that causes a hot, pungent sensation in the human oral cavity. This trigeminal stimulus activates TRPV1 receptors and stimulates an influx of cations into sensory cells. TRPV1 receptors function as homotetramers that also respond to heat, proinflammatory substances, lipoxygenase products, resiniferatoxin, endocannabinoids, protons, and peptide toxins. Kinase-mediated phosphorylation of TRPV1 leads to increased sensitivity to both chemical and thermal stimuli. In contrast, desensitization occurs via a calcium-dependent mechanism that results in receptor dephosphorylation. Human psychophysical studies have shown that capsaicin is detected at nanomole amounts and causes desensitization in the oral cavity. Psychophysical studies further indicate that desensitization can be temporarily reversed in the oral cavity if stimulation with capsaicin is resumed at short interstimulus intervals. Pretreatment of lingual epithelium with capsaicin modulates the perception of several primary taste qualities. Also, sweet taste stimuli may decrease the intensity of capsaicin perception in the oral cavity. In addition, capsaicin perception and hedonic responses may be modified by diet. Psychophysical studies with capsaicin are consistent with recent findings that have identified TRPV1 channel modulation by phosphorylation and interactions with membrane inositol phospholipids. Future studies will further clarify the importance of capsaicin and its receptor in human health and nutrition. PMID:26884754

Does Working Memory Enhance or Interfere With Speech Fluency in Adults Who Do and Do Not Stutter? Evidence From a Dual-Task Paradigm.

PubMed

Eichorn, Naomi; Marton, Klara; Schwartz, Richard G; Melara, Robert D; Pirutinsky, Steven

2016-06-01

The present study examined whether engaging working memory in a secondary task benefits speech fluency. Effects of dual-task conditions on speech fluency, rate, and errors were examined with respect to predictions derived from three related theoretical accounts of disfluencies. Nineteen adults who stutter and twenty adults who do not stutter participated in the study. All participants completed 2 baseline tasks: a continuous-speaking task and a working-memory (WM) task involving manipulations of domain, load, and interstimulus interval. In the dual-task portion of the experiment, participants simultaneously performed the speaking task with each unique combination of WM conditions. All speakers showed similar fluency benefits and decrements in WM accuracy as a result of dual-task conditions. Fluency effects were specific to atypical forms of disfluency and were comparable across WM-task manipulations. Changes in fluency were accompanied by reductions in speaking rate but not by corresponding changes in overt errors. Findings suggest that WM contributes to disfluencies regardless of stuttering status and that engaging WM resources while speaking enhances fluency. Further research is needed to verify the cognitive mechanism involved in this effect and to determine how these findings can best inform clinical intervention.

Musical and linguistic listening modes in the speech-to-song illusion bias timing perception and absolute pitch memory.

PubMed

Graber, Emily; Simchy-Gross, Rhimmon; Margulis, Elizabeth Hellmuth

2017-12-01

The speech-to-song (STS) illusion is a phenomenon in which some spoken utterances perceptually transform to song after repetition [Deutsch, Henthorn, and Lapidis (2011). J. Acoust. Soc. Am. 129, 2245-2252]. Tierney, Dick, Deutsch, and Sereno [(2013). Cereb. Cortex. 23, 249-254] developed a set of stimuli where half tend to transform to perceived song with repetition and half do not. Those that transform and those that do not can be understood to induce a musical or linguistic mode of listening, respectively. By comparing performance on perceptual tasks related to transforming and non-transforming utterances, the current study examines whether the musical mode of listening entails higher sensitivity to temporal regularity and better absolute pitch (AP) memory compared to the linguistic mode. In experiment 1, inter-stimulus intervals within STS trials were steady, slightly variable, or highly variable. Participants reported how temporally regular utterance entrances were. In experiment 2, participants performed an AP memory task after a blocked STS exposure phase. Utterances identically matching those used in the exposure phase were targets among transposed distractors in the test phase. Results indicate that listeners exhibit heightened awareness of temporal manipulations but reduced awareness of AP manipulations to transforming utterances. This methodology establishes a framework for implicitly differentiating musical from linguistic perception.

flexTMS--a novel repetitive transcranial magnetic stimulation device with freely programmable stimulus currents.

PubMed

Gattinger, Norbert; Moessnang, Georg; Gleich, Bernhard

2012-07-01

Transcranial magnetic stimulation (TMS) is able to noninvasively excite neuronal populations due to brief magnetic field pulses. The efficiency and the characteristics of stimulation pulse shapes influence the physiological effect of TMS. However, commercial devices allow only a minimum of control of different pulse shapes. Basically, just sinusoidal and monophasic pulse shapes with fixed pulse widths are available. Only few research groups work on TMS devices with controllable pulse parameters such as pulse shape or pulse width. We describe a novel TMS device with a full-bridge circuit topology incorporating four insulated-gate bipolar transistor (IGBT) modules and one energy storage capacitor to generate arbitrary waveforms. This flexible TMS (flexTMS ) device can generate magnetic pulses which can be adjusted with respect to pulse width, polarity, and intensity. Furthermore, the equipment allows us to set paired pulses with a variable interstimulus interval (ISI) from 0 to 20 ms with a step size of 10  μs. All user-defined pulses can be applied continually with repetition rates up to 30 pulses per second (pps) or, respectively, up to 100 pps in theta burst mode. Offering this variety of flexibility, flexTMS will allow the enhancement of existing TMS paradigms and novel research applications.

Frogs Jump Forward: Semantic Knowledge Influences the Perception of Element Motion in the Ternus Display.

PubMed

Hsu, Patty; Taylor, J Eric T; Pratt, Jay

2015-01-01

The Ternus effect is a robust illusion of motion that produces element motion at short interstimulus intervals (ISIs; < 50 ms) and group motion at longer ISIs (> 50 ms). Previous research has shown that the nature of the stimuli (e.g., similarity, grouping), not just ISI, can influence the likelihood of perceiving element or group motion. We examined if semantic knowledge can also influence what type of illusory motion is perceived. In Experiment I, we used a modified Ternus display with pictures of frogs in a jump-ready pose facing forwards or backwards to the direction of illusory motion. Participants perceived more element motion with the forward-facing frogs and more group motion with the backward-facing frogs. Experiment 2 tested whether this effect would still occur with line drawings of frogs, or if a more life-like image was necessary. Experiment 3 tested whether this effect was due to visual asymmetries inherent in the jumping pose. Experiment 4 tested whether frogs in a "non-jumping," sedentary pose would replicate the original effect. These experiments elucidate the role of semantic knowledge in the Ternus effect. Prior knowledge of the movement of certain animate objects, in this case, frogs can also bias the perception of element or group motion.

Transformations of visual memory induced by implied motions of pattern elements.

PubMed

Finke, R A; Freyd, J J

1985-10-01

Four experiments measured distortions in short-term visual memory induced by displays depicting independent translations of the elements of a pattern. In each experiment, observers saw a sequence of 4 dot patterns and were instructed to remember the third pattern and to compare it with the fourth. The first three patterns depicted translations of the dots in consistent, but separate directions. Error rates and reaction times for rejecting the fourth pattern as different from the third were substantially higher when the dots in that pattern were displaced slightly forward, in the same directions as the implied motions, compared with when the dots were displaced in the opposite, backward directions. These effects showed little variation across interstimulus intervals ranging from 250 to 2,000 ms, and did not depend on whether the displays gave rise to visual apparent motion. However, they were eliminated when the dots in the fourth pattern were displaced by larger amounts in each direction, corresponding to the dot positions in the next and previous patterns in the same inducing sequence. These findings extend our initial report of the phenomenon of "representational momentum" (Freyd & Finke, 1984a), and help to rule out alternatives to the proposal that visual memories tend to undergo, at least to some extent, the transformations implied by a prior sequence of observed events.

Blink reflex recovery cycle to differentiate Progressive Supranuclear Palsy from Cortico-basal syndrome.

PubMed

Sciacca, Giorgia; Nicoletti, Alessandra; Mostile, Giovanni; Luca, Antonina; Raciti, Loredana; Dibilio, Valeria; Drago, Filippo; Salomone, Salvatore; Zappia, Mario

2018-05-13

Progressive Supranuclear Palsy (PSP) and Cortico-basal syndrome (CBS) may share similar clinical findings and peculiar tests to distinguish between the two disorders could be useful. We evaluated Blink Reflex (BR) and R2 Blink Reflex Recovery Cycle (R2BRRC), determining diagnostic sensitivity, specificity, positive and negative predictive value of R2BRRC in differentiating PSP from CBS patients. This was a prospective data collection study investigating BR and R2BRRC at interstimulus intervals (ISIs) of 100, 150, 200, 300, 400, 500, 750 ms in 12 PSP patients, 8 CBS patients, and 10 controls. Patients with PSP have earlier recruitment of R2BRRC as compared to patients with CBS (ISI 100: p=0.002; ISI 150: p<0.001; ISI 200: p<0.001; ISI 300: p=0.02) and controls (ISI 100: p<0.001; ISI 150: p<0.001; ISI 200: p<0.001; ISI 300: p=0.004). The presence of an early recovery of the R2 differentiated PSP from CBS with specificity and sensitivity of 87.5% and 91.7% respectively. R2BRRC curve might be considered a useful tool in differentiating PSP from CBS patients. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Does temporal contiguity moderate contingency learning in a speeded performance task?

PubMed

Schmidt, James R; De Houwer, Jan

2012-01-01

In four experiments, we varied the time between the onset of distracting nonwords and target colour words in a word-word version of the colour-word contingency learning paradigm. Contingencies were created by pairing a distractor nonword more often with one target colour word than with other colour words. A contingency effect corresponds to faster responses to the target colour word on high-contingency trials (i.e., distractor nonword followed by the target colour word with which it appears most often) than on low-contingency trials (i.e., distractor nonword followed by a target colour word with which it appears only occasionally). Roughly equivalent-sized contingency effects were found at stimulus-onset asynchronies (SOAs) of 50, 250, and 450 ms in Experiment 1, and 50, 500, and 1,000 ms in Experiment 2. In Experiment 3, a contingency effect was observed at SOAs of -50, -200, and -350 ms. In Experiment 4, interstimulus interval (ISI) was varied along with SOA, and learning was equivalent for 200-, 700-, and 1,200-ms SOAs. Together, these experiments suggest that the distracting stimulus does not need to be presented in close temporal contiguity with the response to induce learning. Relations to past research on causal judgement and implications for further contingency learning research are discussed.

A study of adaptation mechanisms based on ABR recorded at high stimulation rate.

PubMed

Valderrama, Joaquin T; de la Torre, Angel; Alvarez, Isaac; Segura, Jose Carlos; Thornton, A Roger D; Sainz, Manuel; Vargas, Jose Luis

2014-04-01

This paper analyzes the fast and slow mechanisms of adaptation through a study of latencies and amplitudes on ABR recorded at high stimulation rates using the randomized stimulation and averaging (RSA) technique. The RSA technique allows a separate processing of auditory responses, and is used, in this study, to categorize responses according to the interstimulus interval (ISI) of their preceding stimulus. The fast and slow mechanisms of adaptation are analyzed by the separated responses methodology, whose underlying principles and mathematical basis are described in detail. The morphology of the ABR is influenced by both fast and slow mechanisms of adaptation. These results are consistent with previous animal studies based on spike rate. Both fast and slow mechanisms of adaptation are present in all subjects. In addition, the distribution of the jitter and the sequencing of the stimuli may be critical parameters when obtaining reliable ABRs. The separated responses methodology enables for the first time the analysis of the fast and slow mechanisms of adaptation in ABR obtained at stimulation rates greater than 100 Hz. The non-invasive nature of this methodology is appropriate for its use in humans. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Auditory phase and frequency discrimination: a comparison of nine procedures.

PubMed

Creelman, C D; Macmillan, N A

1979-02-01

Two auditory discrimination tasks were thoroughly investigated: discrimination of frequency differences from a sinusoidal signal of 200 Hz and discrimination of differences in relative phase of mixed sinusoids of 200 Hz and 400 Hz. For each task psychometric functions were constructed for three observers, using nine different psychophysical measurement procedures. These procedures included yes-no, two-interval forced-choice, and various fixed- and variable-standard designs that investigators have used in recent years. The data showed wide ranges of apparent sensitivity. For frequency discrimination, models derived from signal detection theory for each psychophysical procedure seem to account for the performance differences. For phase discrimination the models do not account for the data. We conclude that for some discriminative continua the assumptions of signal detection theory are appropriate, and underlying sensitivity may be derived from raw data by appropriate transformations. For other continua the models of signal detection theory are probably inappropriate; we speculate that phase might be discriminable only on the basis of comparison or change and suggest some tests of our hypothesis.

Discrimination of Variable Schedules Is Controlled by Interresponse Times Proximal to Reinforcement

ERIC Educational Resources Information Center

Tanno, Takayuki; Silberberg, Alan; Sakagami, Takayuki

2012-01-01

In Experiment 1, food-deprived rats responded to one of two schedules that were, with equal probability, associated with a sample lever. One schedule was always variable ratio, while the other schedule, depending on the trial within a session, was: (a) a variable-interval schedule; (b) a tandem variable-interval,…

Ambiguity domain-based identification of altered gait pattern in ALS disorder

NASA Astrophysics Data System (ADS)

Sugavaneswaran, L.; Umapathy, K.; Krishnan, S.

2012-08-01

The onset of a neurological disorder, such as amyotrophic lateral sclerosis (ALS), is so subtle that the symptoms are often overlooked, thereby ruling out the option of early detection of the abnormality. In the case of ALS, over 75% of the affected individuals often experience awkwardness when using their limbs, which alters their gait, i.e. stride and swing intervals. The aim of this work is to suitably represent the non-stationary characteristics of gait (fluctuations in stride and swing intervals) in order to facilitate discrimination between normal and ALS subjects. We define a simple-yet-representative feature vector space by exploiting the ambiguity domain (AD) to achieve efficient classification between healthy and pathological gait stride interval. The stride-to-stride fluctuations and the swing intervals of 16 healthy control and 13 ALS-affected subjects were analyzed. Three features that are representative of the gait signal characteristics were extracted from the AD-space and are fed to linear discriminant analysis and neural network classifiers, respectively. Overall, maximum accuracies of 89.2% (LDA) and 100% (NN) were obtained in classifying the ALS gait.

Increased Inhibition in Non-Primary Motor Areas of String-Instrument Players: A Preliminary Study with Paired-Pulse Transcranial Magnetic Stimulation

PubMed Central

Vaalto, Selja; Julkunen, Petro; Säïsänen, Laura; Könönen, Mervi; Määttä, Sara; Karhu, Jari

2016-01-01

Background: The muscle representations in non-primary motor area (NPMA) are located in the dorsal premotor area (PMd) and in the border region between the premotor area and the supplementary motor area (SMA). Objective: We characterized the plasticity of intracortical inhibitory and excitatory circuits in muscle representations in primary motor cortex (M1) and in NPMA related to acquired fine motor skills. We compared local cortical inhibition and facilitation balance in M1 and in NPMA between control subjects (n = 6) and right-handed string-instrument players (n = 5). Methods: Navigated transcranial magnetic stimulation (TMS) was used to compare motor thresholds (MTs), motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) in non-dominant hand muscle representations in M1 and NPMA. Results: String-instrument players showed reduced SICI in M1 in the actively used left hand abductor digiti minimi (ADM) muscle representation at 3 ms inter-stimulus interval (ISI) with a conditioning stimulus (CS) intensity of 80% of MT and increased SICI in NPMA in ADM representation at 2 ms ISI and CS intensity of 50% of MT in comparison with controls. No differences between string-instrument players and controls were found for the SICI in the left hand opponens pollicis (OP) muscle representation, which is a muscle not intensively trained in string-instrument players. Conclusions: These preliminary results indicate that the stronger inhibition in motor representations outside M1 in string-instrument players may be crucial when accurate movements of single muscles must be performed. In contrast, weaker inhibition in M1 in string-instrument players may benefit the performance of fast finger movements. PMID:29765844

Serial position effects in recognition memory for odors: a reexamination.

PubMed

Miles, Christopher; Hodder, Kathryn

2005-10-01

Seven experiments examined recognition memory for sequentially presented odors. Following Reed (2000), participants were presented with a sequence of odors and then required to identify an odor from the sequence in a test probe comprising 2 odors. The pattern of results obtained by Reed (2000, although statistically marginal) demonstrated enhanced recognition for odors presented at the start (primacy) and end (recency) of the sequence: a result that we failed to replicate in any of the experiments reported here. Experiments 1 and 3 were designed to replicate Reed (2000), employing five-item and seven-item sequences, respectively, and each demonstrated significant recency, with evidence of primacy in Experiment 3 only. Experiment 2 replicated Experiment 1, with reduced interstimulus intervals, and produced a null effect of serial position. The ease with which the odors could be verbally labeled was manipulated in Experiments 4 and 5. Nameable odors produced a null effect of serial position (Experiment 4), and hard-to-name odors produced a pronounced recency effect (Experiment 5); nevertheless, overall rates of recognition were remarkably similar for the two experiments at around 70%. Articulatory suppression reduced recognition accuracy (Experiment 6), but recency was again present in the absence of primacy. Odor recognition performance was immune to the effects of an interleaved odor (Experiment 7), and, again, both primacy and recency effects were absent. There was no evidence of olfactory fatigue: Recognition accuracy improved across trials (Experiment 1). It is argued that the results of the experiments reported here are generally consistent with that body of work employing hard-to-name visual stimuli, where recency is obtained in the absence of primacy when the retention interval is short.

Modulation of soleus corticospinal excitability during Achilles tendon vibration.

PubMed

Lapole, Thomas; Temesi, John; Arnal, Pierrick J; Gimenez, Philippe; Petitjean, Michel; Millet, Guillaume Y

2015-09-01

Soleus (SOL) corticospinal excitability has been reported to increase during Achilles tendon vibration. The aim of the present study was to further investigate SOL corticospinal excitability and elucidate the changes to intracortical mechanisms during Achilles tendon vibration. Motor-evoked potentials (MEPs) were elicited in the SOL by transcranial magnetic stimulation (TMS) of the corresponding motor cortical area of the leg with and without 50-Hz Achilles tendon vibration. SOL input-output curves were determined. Paired-pulse protocols were also performed to investigate short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) by conditioning test TMS pulses with sub-threshold TMS pulses at inter-stimulus intervals of 3 and 13 ms, respectively. During Achilles tendon vibration, motor threshold was lower than in the control condition (43 ± 13 vs. 49 ± 11 % of maximal stimulator output; p = 0.008). Input-output curves were also influenced by vibration, i.e. there was increased maximal MEP amplitude (0.694 ± 0.347 vs. 0.268 ± 0.167 mV; p < 0.001), decreased TMS intensity to elicit a MEP of half the maximal MEP amplitude (100 ± 13 vs. 109 ± 9 % motor threshold; p = 0.009) and a strong tendency for decreased slope constant (0.076 ± 0.04 vs. 0.117 ± 0.04; p = 0.068). Vibration reduced ICF (98 ± 61 vs. 170 ± 105 % of test MEP amplitude; p = 0.05), but had no effect on SICI (53 ± 26 vs. 48 ± 22 % of test MEP amplitude; p = 0.68). The present results further document the increased vibration-induced corticospinal excitability in the soleus muscle and suggest that this increase is not mediated by changes in SICI or ICF.

Glued to Which Face? Attentional Priority Effect of Female Babyface and Male Mature Face

PubMed Central

Zheng, Wenwen; Luo, Ting; Hu, Chuan-Peng; Peng, Kaiping

2018-01-01

A more babyfaced individual is perceived as more child-like and this impression from babyface, as known as babyface effect, has an impact on social life among various age groups. In this study, the influence of babyfaces on visual selective attention was tested by cognitive task, demonstrating that the female babyface and male mature face would draw participants’ attention so that they take their eyes off more slowly. In Experiment 1, a detection task was applied to test the influence of babyfaces on visual selective attention. In this experiment, a babyface and a mature face with the same gender were presented simultaneously with a letter on one of them. The reaction time was shorter when the target letter was overlaid with a female babyface or male mature face, suggesting an attention capture effect. To explore how this competition influenced by attentional resources, we conducted Experiment 2 with a spatial cueing paradigm and controlled the attentional resources by cueing validity and inter-stimulus interval. In this task, the female babyface and male mature face prolonged responses to the spatially separated targets under the condition of an invalid and long interval pre-cue. This observation replicated the result of Experiment 1. This indicates that the female babyface and male mature face glued visual selective attention once attentional resources were directed to them. To further investigate the subliminal influence from a babyface, we used continuous flash suppression paradigm in Experiment 3. The results, again, showed the advantage of the female babyfaces and male mature faces: they broke the suppression faster than other faces. Our results provide primary evidence that the female babyfaces and male mature faces can reliably glue the visual selective attention, both supra- and sub-liminally. PMID:29559946

22q11.2 Deletion Syndrome Is Associated With Impaired Auditory Steady-State Gamma Response

PubMed Central

Pellegrino, Giovanni; Birknow, Michelle Rosgaard; Kjær, Trine Nørgaard; Baaré, William Frans Christiaan; Didriksen, Michael; Olsen, Line; Werge, Thomas; Mørup, Morten; Siebner, Hartwig Roman

2018-01-01

Abstract Background The 22q11.2 deletion syndrome confers a markedly increased risk for schizophrenia. 22q11.2 deletion carriers without manifest psychotic disorder offer the possibility to identify functional abnormalities that precede clinical onset. Since schizophrenia is associated with a reduced cortical gamma response to auditory stimulation at 40 Hz, we hypothesized that the 40 Hz auditory steady-state response (ASSR) may be attenuated in nonpsychotic individuals with a 22q11.2 deletion. Methods Eighteen young nonpsychotic 22q11.2 deletion carriers and a control group of 27 noncarriers with comparable age range (12–25 years) and sex ratio underwent 128-channel EEG. We recorded the cortical ASSR to a 40 Hz train of clicks, given either at a regular inter-stimulus interval of 25 ms or at irregular intervals jittered between 11 and 37 ms. Results Healthy noncarriers expressed a stable ASSR to regular but not in the irregular 40 Hz click stimulation. Both gamma power and inter-trial phase coherence of the ASSR were markedly reduced in the 22q11.2 deletion group. The ability to phase lock cortical gamma activity to regular auditory 40 Hz stimulation correlated with the individual expression of negative symptoms in deletion carriers (ρ = −0.487, P = .041). Conclusions Nonpsychotic 22q11.2 deletion carriers lack efficient phase locking of evoked gamma activity to regular 40 Hz auditory stimulation. This abnormality indicates a dysfunction of fast intracortical oscillatory processing in the gamma-band. Since ASSR was attenuated in nonpsychotic deletion carriers, ASSR deficiency may constitute a premorbid risk marker of schizophrenia. PMID:28521049

The effect of prenatal methamphetamine exposure on attention as assessed by continuous performance tests: results from the Infant Development, Environment, and Lifestyle study.

PubMed

Kiblawi, Zeina N; Smith, Lynne M; LaGasse, Linda L; Derauf, Chris; Newman, Elana; Shah, Rizwan; Arria, Amelia; Huestis, Marilyn; DellaGrotta, Sheri; Dansereau, Lynne M; Neal, Charles; Lester, Barry

2013-01-01

To assess for the increased risk of attention-deficit hyperactivity disorder (ADHD) in young children with prenatal methamphetamine exposure from the multicenter, longitudinal Infant Development, Environment, and Lifestyle (IDEAL) study. The IDEAL study enrolled 412 mother-infant pairs at 4 sites (Tulsa, OK; Des Moines, IA; Los Angeles, CA; and Honolulu, HI). Methamphetamine-exposed subjects (n = 204) were identified by self-report and/or gas chromatography/mass spectrometry confirmation of amphetamine and metabolites in infant meconium. Matched subjects (n = 208) denied methamphetamine use and had a negative meconium screen. This analysis included a subsample of 301 subjects who were administered the Conners' Kiddie Continuous Performance Test (K-CPT) at 5.5 years of age (153 exposed and 148 comparison). Hierarchical linear models adjusted for covariates tested exposure effects on K-CPT measures. Using the same covariates, logistic regression was used to determine the effect of exposure on the incidence of a positive ADHD confidence index score, defined as greater than 50%. There were no differences between the groups in omission or commission errors or reaction time for correct trials. However, methamphetamine exposure was associated with subtle differences in other outcomes predictive of ADHD, including increased slope of reaction time across blocks (p < .001), increased variability in reaction time with longer interstimulus intervals (p < .01), and increased likelihood of greater than 50% on the ADHD confidence index (odds ratio, 3.1; 95% confidence interval, 1.2-7.8; p = .02). Prenatal methamphetamine exposure was associated with subtle differences in K-CPT scores at 5.5 years of age. Even at this relatively young age, these children exhibit indicators of risk for ADHD and warrant monitoring.

Glued to Which Face? Attentional Priority Effect of Female Babyface and Male Mature Face.

PubMed

Zheng, Wenwen; Luo, Ting; Hu, Chuan-Peng; Peng, Kaiping

2018-01-01

A more babyfaced individual is perceived as more child-like and this impression from babyface, as known as babyface effect, has an impact on social life among various age groups. In this study, the influence of babyfaces on visual selective attention was tested by cognitive task, demonstrating that the female babyface and male mature face would draw participants' attention so that they take their eyes off more slowly. In Experiment 1, a detection task was applied to test the influence of babyfaces on visual selective attention. In this experiment, a babyface and a mature face with the same gender were presented simultaneously with a letter on one of them. The reaction time was shorter when the target letter was overlaid with a female babyface or male mature face, suggesting an attention capture effect. To explore how this competition influenced by attentional resources, we conducted Experiment 2 with a spatial cueing paradigm and controlled the attentional resources by cueing validity and inter-stimulus interval. In this task, the female babyface and male mature face prolonged responses to the spatially separated targets under the condition of an invalid and long interval pre-cue. This observation replicated the result of Experiment 1. This indicates that the female babyface and male mature face glued visual selective attention once attentional resources were directed to them. To further investigate the subliminal influence from a babyface, we used continuous flash suppression paradigm in Experiment 3. The results, again, showed the advantage of the female babyfaces and male mature faces: they broke the suppression faster than other faces. Our results provide primary evidence that the female babyfaces and male mature faces can reliably glue the visual selective attention, both supra- and sub-liminally.

Age-related Differences in Pre- and Post-synaptic Motor Cortex Inhibition are Task Dependent.

PubMed

Opie, George M; Ridding, Michael C; Semmler, John G

2015-01-01

Previous research has shown age-related differences in short- (SICI) and long-interval intracortical inhibition (LICI) in both resting and active hand muscles, suggesting that healthy ageing influences post-synaptic motor cortex inhibition. However, it is not known how the ageing process effects the pre-synaptic interaction of SICI by LICI, and how these pre- and post-synaptic intracortical inhibitory circuits are modulated by the performance of different motor tasks in older adults. To examine age-related differences in pre- and post-synaptic motor cortex inhibition at rest, and during index finger abduction and precision grip. In 13 young (22.3 ± 3.8 years) and 15 old (73.7 ± 4.0 years) adults, paired-pulse transcranial magnetic stimulation (TMS) was used to measure SICI (2 ms inter-stimulus interval; ISI) and LICI (100 and 150 ms ISI), whereas triple-pulse TMS was used to investigate SICI when primed by LICI. We found no age-related difference in SICI at rest or during index finger abduction, but significantly greater SICI in older subjects during precision grip. Older adults showed reduced LICI in resting muscle (at an ISI of 150 ms), with no age-related differences in LICI during either task. When SICI was primed by LICI, disinhibition of motor cortex was reduced in older adults at rest (100 ms ISI) and during index finger abduction (150 ms ISI), but not during precision grip. Our results support age-related differences in pre- and post-synaptic motor cortex inhibition, which may contribute to impaired hand function during task performance in older adults. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of increasing time delays on pitch-matching accuracy in trained singers and untrained individuals.

PubMed

Estis, Julie M; Coblentz, Joana K; Moore, Robert E

2009-07-01

Trained singers (TS) generally demonstrate accurate pitch matching, but this ability varies within the general population. Pitch-matching accuracy, given increasing silence intervals of 5, 15, and 25 seconds between target tones and vocal matches, was investigated in TS and untrained individuals. A relationship between pitch discrimination and pitch matching was also examined. Thirty-two females (20-30 years) were grouped based on individual vocal training and performance in an immediate pitch-matching task. Participants matched target pitches following time delays, and completed a pitch discrimination task, which required the classification of two tones as same or different. TS and untrained accurate participants performed comparably on all pitch-matching tasks, while untrained inaccurate participants performed significantly less accurately than the other two groups. Performances declined across groups as intervals of silence increased, suggesting degradation of pitch matching as pitch memory was taxed. A significant relationship between pitch discrimination and pitch matching was revealed across participants.

Risk score to predict hospital-acquired pneumonia after spontaneous intracerebral hemorrhage.

PubMed

Ji, Ruijun; Shen, Haipeng; Pan, Yuesong; Du, Wanliang; Wang, Penglian; Liu, Gaifen; Wang, Yilong; Li, Hao; Zhao, Xingquan; Wang, Yongjun

2014-09-01

We aimed to develop a risk score (intracerebral hemorrhage-associated pneumonia score, ICH-APS) for predicting hospital-acquired stroke-associated pneumonia (SAP) after ICH. The ICH-APS was developed based on the China National Stroke Registry (CNSR), in which eligible patients were randomly divided into derivation (60%) and validation (40%) cohorts. Variables routinely collected at presentation were used for predicting SAP after ICH. For testing the added value of hematoma volume measure, we separately developed 2 models with (ICH-APS-B) and without (ICH-APS-A) hematoma volume included. Multivariable logistic regression was performed to identify independent predictors. The area under the receiver operating characteristic curve (AUROC), Hosmer-Lemeshow goodness-of-fit test, and integrated discrimination index were used to assess model discrimination, calibration, and reclassification, respectively. The SAP was 16.4% and 17.7% in the overall derivation (n=2998) and validation (n=2000) cohorts, respectively. A 23-point ICH-APS-A was developed based on a set of predictors and showed good discrimination in the overall derivation (AUROC, 0.75; 95% confidence interval, 0.72-0.77) and validation (AUROC, 0.76; 95% confidence interval, 0.71-0.79) cohorts. The ICH-APS-A was more sensitive for patients with length of stay >48 hours (AUROC, 0.78; 95% confidence interval, 0.75-0.81) than those with length of stay <48 hours (AUROC, 0.64; 95% confidence interval, 0.55-0.73). The ICH-APS-A was well calibrated (Hosmer-Lemeshow test) in the derivation (P=0.20) and validation (P=0.66) cohorts. Similarly, a 26-point ICH-APS-B was established. The ICH-APS-A and ICH-APS-B were not significantly different in discrimination and reclassification for SAP after ICH. The ICH-APSs are valid risk scores for predicting SAP after ICH, especially for patients with length of stay >48 hours. © 2014 American Heart Association, Inc.

Image discrimination models predict detection in fixed but not random noise

NASA Technical Reports Server (NTRS)

Ahumada, A. J. Jr; Beard, B. L.; Watson, A. B. (Principal Investigator)

1997-01-01

By means of a two-interval forced-choice procedure, contrast detection thresholds for an aircraft positioned on a simulated airport runway scene were measured with fixed and random white-noise masks. The term fixed noise refers to a constant, or unchanging, noise pattern for each stimulus presentation. The random noise was either the same or different in the two intervals. Contrary to simple image discrimination model predictions, the same random noise condition produced greater masking than the fixed noise. This suggests that observers seem unable to hold a new noisy image for comparison. Also, performance appeared limited by internal process variability rather than by external noise variability, since similar masking was obtained for both random noise types.

Cross-sectional association between perceived discrimination and hypertension in African-American men and women: the Pitt County Study.

PubMed

Roberts, Calpurnyia B; Vines, Anissa I; Kaufman, Jay S; James, Sherman A

2008-03-01

Few studies have examined the impact of the frequency of discrimination on hypertension risk. The authors assessed the cross-sectional associations between frequency of perceived racial and nonracial discrimination and hypertension among 1,110 middle-aged African-American men (n = 393) and women (n = 717) participating in the 2001 follow-up of the Pitt County Study (Pitt County, North Carolina). Odds ratios were estimated using gender-specific unconditional weighted logistic regression with adjustment for relevant confounders and the frequency of discrimination. More than half of the men (57%) and women (55%) were hypertensive. The prevalences of perceived racial discrimination, nonracial discrimination, and no discrimination were 57%, 29%, and 13%, respectively, in men and 42%, 43%, and 15%, respectively, in women. Women recounting frequent nonracial discrimination versus those reporting no exposure to discrimination had the highest odds of hypertension (adjusted odds ratio = 2.34, 95% confidence interval: 1.09, 5.02). A nonsignificant inverse odds ratio was evident in men who perceived frequent exposure to racial or nonracial discrimination in comparison with no exposure. A similar association was observed for women reporting perceived racial discrimination. These results indicate that the type and frequency of discrimination perceived by African-American men and women may differentially affect their risk of hypertension.

Discrimination of edible oils and fats by combination of multivariate pattern recognition and FT-IR spectroscopy: A comparative study between different modeling methods

NASA Astrophysics Data System (ADS)

Javidnia, Katayoun; Parish, Maryam; Karimi, Sadegh; Hemmateenejad, Bahram

2013-03-01

By using FT-IR spectroscopy, many researchers from different disciplines enrich the experimental complexity of their research for obtaining more precise information. Moreover chemometrics techniques have boosted the use of IR instruments. In the present study we aimed to emphasize on the power of FT-IR spectroscopy for discrimination between different oil samples (especially fat from vegetable oils). Also our data were used to compare the performance of different classification methods. FT-IR transmittance spectra of oil samples (Corn, Colona, Sunflower, Soya, Olive, and Butter) were measured in the wave-number interval of 450-4000 cm-1. Classification analysis was performed utilizing PLS-DA, interval PLS-DA, extended canonical variate analysis (ECVA) and interval ECVA methods. The effect of data preprocessing by extended multiplicative signal correction was investigated. Whilst all employed method could distinguish butter from vegetable oils, iECVA resulted in the best performances for calibration and external test set with 100% sensitivity and specificity.

Auditory Pattern Memory

DTIC Science & Technology

1990-10-31

Creelman , 1962; Getty, 1975; Divenyi and Danner, kin et aL (1982) jitter-detection paradigm. An advantage of 1977; Divenyi and Sachs, 1978; and Allen...discrimination of tonal se- Creelman . C. D. (1962). "’Human discrimination ofauditory duration." 3. quences.’" J. Acoust. Soc. Am. 82.1218-1226. Acoust...single marked intervals (Abel, 1972a,b; Creelman , 1962; Getty, 1975; Divenyi and Danner, 1977; Divenyi and Sachs, 1978; Espinoza-Varas and Jamieson

Individual variability in visual discrimination and reversal learning performance in common marmosets.

PubMed

Takemoto, Atsushi; Miwa, Miki; Koba, Reiko; Yamaguchi, Chieko; Suzuki, Hiromi; Nakamura, Katsuki

2015-04-01

Detailed information about the characteristics of learning behavior in marmosets is useful for future marmoset research. We trained 42 marmosets in visual discrimination and reversal learning. All marmosets could learn visual discrimination, and all but one could complete reversal learning, though some marmosets failed to touch the visual stimuli and were screened out. In 87% of measurements, the final percentage of correct responses was over 95%. We quantified performance with two measures: onset trial and dynamic interval. Onset trial represents the number of trials that elapsed before the marmoset started to learn. Dynamic interval represents the number of trials from the start before reaching the final percentage of correct responses. Both measures decreased drastically as a result of the formation of discrimination learning sets. In reversal learning, both measures worsened, but the effect on onset trial was far greater. The effects of age and sex were not significant as far as we used adolescent or young adult marmosets. Unexpectedly, experimental circumstance (in the colony or isolator) had only a subtle effect on performance. However, we found that marmosets from different families exhibited different learning process characteristics, suggesting some family effect on learning. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Dynamic detection-rate-based bit allocation with genuine interval concealment for binary biometric representation.

PubMed

Lim, Meng-Hui; Teoh, Andrew Beng Jin; Toh, Kar-Ann

2013-06-01

Biometric discretization is a key component in biometric cryptographic key generation. It converts an extracted biometric feature vector into a binary string via typical steps such as segmentation of each feature element into a number of labeled intervals, mapping of each interval-captured feature element onto a binary space, and concatenation of the resulted binary output of all feature elements into a binary string. Currently, the detection rate optimized bit allocation (DROBA) scheme is one of the most effective biometric discretization schemes in terms of its capability to assign binary bits dynamically to user-specific features with respect to their discriminability. However, we learn that DROBA suffers from potential discriminative feature misdetection and underdiscretization in its bit allocation process. This paper highlights such drawbacks and improves upon DROBA based on a novel two-stage algorithm: 1) a dynamic search method to efficiently recapture such misdetected features and to optimize the bit allocation of underdiscretized features and 2) a genuine interval concealment technique to alleviate crucial information leakage resulted from the dynamic search. Improvements in classification accuracy on two popular face data sets vindicate the feasibility of our approach compared with DROBA.

Evaluation of fixed momentary dro schedules under signaled and unsignaled arrangements.

PubMed

Hammond, Jennifer L; Iwata, Brian A; Fritz, Jennifer N; Dempsey, Carrie M

2011-01-01

Fixed momentary schedules of differential reinforcement of other behavior (FM DRO) generally have been ineffective as treatment for problem behavior. Because most early research on FM DRO included presentation of a signal at the end of the DRO interval, it is unclear whether the limited effects of FM DRO were due to (a) the momentary response requirement of the schedule per se or (b) discrimination of the contingency made more salient by the signal. To separate these two potential influences, we compared the effects of signaled versus unsignaled FM DRO with 4 individuals with developmental disabilities whose problem behavior was maintained by social-positive reinforcement. During signaled FM DRO, the experimenter presented a visual stimulus 3 s prior to the end of the DRO interval and delivered reinforcement contingent on the absence of problem behavior at the second the interval elapsed. Unsignaled DRO was identical except that interval termination was not signaled. Results indicated that signaled FM DRO was effective in decreasing 2 subjects' problem behavior, whereas an unsignaled schedule was required for the remaining 2 subjects. These results suggest that the response requirement per se of FM DRO may not be problematic if it is not easily discriminated.

T-wave morphology can distinguish healthy controls from LQTS patients.

PubMed

Immanuel, S A; Sadrieh, A; Baumert, M; Couderc, J P; Zareba, W; Hill, A P; Vandenberg, J I

2016-09-01

Long QT syndrome (LQTS) is an inherited disorder associated with prolongation of the QT/QTc interval on the surface electrocardiogram (ECG) and a markedly increased risk of sudden cardiac death due to cardiac arrhythmias. Up to 25% of genotype-positive LQTS patients have QT/QTc intervals in the normal range. These patients are, however, still at increased risk of life-threatening events compared to their genotype-negative siblings. Previous studies have shown that analysis of T-wave morphology may enhance discrimination between control and LQTS patients. In this study we tested the hypothesis that automated analysis of T-wave morphology from Holter ECG recordings could distinguish between control and LQTS patients with QTc values in the range 400-450 ms. Holter ECGs were obtained from the Telemetric and Holter ECG Warehouse (THEW) database. Frequency binned averaged ECG waveforms were obtained and extracted T-waves were fitted with a combination of 3 sigmoid functions (upslope, downslope and switch) or two 9th order polynomial functions (upslope and downslope). Neural network classifiers, based on parameters obtained from the sigmoid or polynomial fits to the 1 Hz and 1.3 Hz ECG waveforms, were able to achieve up to 92% discrimination between control and LQTS patients and 88% discrimination between LQTS1 and LQTS2 patients. When we analysed a subgroup of subjects with normal QT intervals (400-450 ms, 67 controls and 61 LQTS), T-wave morphology based parameters enabled 90% discrimination between control and LQTS patients, compared to only 71% when the groups were classified based on QTc alone. In summary, our Holter ECG analysis algorithms demonstrate the feasibility of using automated analysis of T-wave morphology to distinguish LQTS patients, even those with normal QTc, from healthy controls.

Perceived Discrimination and Personality Development in Adulthood

PubMed Central

Stephan, Yannick; Terracciano, Antonio

2015-01-01

Perceived discrimination is common and a significant source of stress that may have implications for personality development across adulthood. In this study, we examined whether experiences with discrimination were associated with maladaptive changes in the five major dimensions of personality using two longitudinal samples that differed in age and follow-up interval. In the Health and Retirement Study, participants who perceived discrimination increased in their tendency to experience negative emotions (Neuroticism), decreased in their tendency to be trusting (Agreeableness), and decreased in their tendency to be organized and disciplined (Conscientiousness). These associations replicated using participants from the Midlife in the United States study. The findings indicate that social pathways, in addition to biological and developmental tasks, are important for adult personality development. PMID:26501729

The Effects of Discrimination Are Associated With Cigarette Smoking Among Black Males.

PubMed

Parker, Lauren J; Hunte, Haslyn; Ohmit, Anita; Furr-Holden, Debra; Thorpe, Roland J

2017-02-23

Previous research has demonstrated that experiencing interpersonal discrimination is associated with cigarette smoking. Few studies have examined the relationship between the effects of physical and emotional discrimination and cigarette usage, and none have examined this relationship among Black men. The aim of this study was to examine the association between the effects of physical and emotional discrimination and cigarette smoking. Data from the Indiana Black Men's Health Study, a community-based sample of adult Black men, was used to conduct multivariate logistic regression to examine the relationship between the physical and emotional effects of discrimination and smoking, net of healthcare and workplace discrimination, age, education, household income, and being married. After adjusting for having an emotional response to discrimination, health care and workplace discrimination, age, education, household income, and being married, males who had a physical response to discrimination (e.g., upset stomach or headache) had higher odds of cigarette use (odds ratio (OR): 1.95, 95% confidence interval (CI): 1.15-3.30) than men who did not have a physical response to discrimination. Findings from the study suggest that Black males may use cigarette smoking as a means to mitigate the stress associated with experiences of discrimination. Future research is needed further to explore if and how Black males use cigarette smoking to cope with unfair treatment.

Menstrual cycle and the temporal discrimination threshold.

PubMed

Mc Govern, Eavan M; O'Connor, Emer; Beiser, Ines; Williams, Laura; Butler, John S; Quinlivan, Brendan; Narasimham, Shruti; Beck, Rebecca; Reilly, Richard B; O'Riordan, Sean; Hutchinson, Michael

2017-02-01

The temporal discrimination threshold (TDT) is a proposed pre-clinical biomarker (endophenotype) for adult onset isolated focal dystonia (AOIFD). Age- and sex-related effects on temporal discrimination demonstrate that women, before the age of 40 years, have faster temporal discrimination than men but their TDTs worsen with age at almost three times the rate of men. Thus after 40 years the TDT in women is progressively worse than in men. AOIFD is an increasingly female-predominant disorder after the age of 40; it is not clear whether this age-related sexually-dimorphic difference observed for both the TDT and sex ratio at disease onset in AOIFD is a hormonal or chromosomal effect. The aim of this study was to examine temporal discrimination at weekly intervals during two consecutive menstrual cycles in 14 healthy female volunteers to determine whether physiological hormonal changes affected temporal discrimination. We observed no significant differences in weekly temporal discrimination threshold values during the menstrual cycles and no significant correlation with the menstrual cycle stage. This observed stability of temporal discrimination during cyclical hormonal change raises interesting questions concerning the age-related sexually-dimorphic decline observed in temporal discrimination. Our findings pave the way for future studies exploring potential pathomechanisms for this age-related deterioration.

Accuracy of cochlear implant recipients on pitch perception, melody recognition, and speech reception in noise.

PubMed

Gfeller, Kate; Turner, Christopher; Oleson, Jacob; Zhang, Xuyang; Gantz, Bruce; Froman, Rebecca; Olszewski, Carol

2007-06-01

The purposes of this study were to (a) examine the accuracy of cochlear implant recipients who use different types of devices and signal processing strategies on pitch ranking as a function of size of interval and frequency range and (b) to examine the relations between this pitch perception measure and demographic variables, melody recognition, and speech reception in background noise. One hundred fourteen cochlear implant users and 21 normal-hearing adults were tested on a pitch discrimination task (pitch ranking) that required them to determine direction of pitch change as a function of base frequency and interval size. Three groups were tested: (a) long electrode cochlear implant users (N = 101); (b) short electrode users that received acoustic plus electrical stimulation (A+E) (N = 13); and (c) a normal-hearing (NH) comparison group (N = 21). Pitch ranking was tested at standard frequencies of 131 to 1048 Hz, and the size of the pitch-change intervals ranged from 1 to 4 semitones. A generalized linear mixed model (GLMM) was fit to predict pitch ranking and to determine if group differences exist as a function of base frequency and interval size. Overall significance effects were measured with Chi-square tests and individual effects were measured with t-tests. Pitch ranking accuracy was correlated with demographic measures (age at time of testing, length of profound deafness, months of implant use), frequency difference limens, familiar melody recognition, and two measures of speech reception in noise. The long electrode recipients performed significantly poorer on pitch discrimination than the NH and A+E group. The A+E users performed similarly to the NH listeners as a function of interval size in the lower base frequency range, but their pitch discrimination scores deteriorated slightly in the higher frequency range. The long electrode recipients, although less accurate than participants in the NH and A+E groups, tended to perform with greater accuracy within the higher frequency range. There were statistically significant correlations between pitch ranking and familiar melody recognition as well as with pure-tone frequency difference limens at 200 and 400 Hz. Low-frequency acoustic hearing improves pitch discrimination as compared with traditional, electric-only cochlear implants. These findings have implications for musical tasks such as familiar melody recognition.

Neural activity related to discrimination and vocal production of consonant and dissonant musical intervals.

PubMed

González-García, Nadia; González, Martha A; Rendón, Pablo L

2016-07-15

Relationships between musical pitches are described as either consonant, when associated with a pleasant and harmonious sensation, or dissonant, when associated with an inharmonious feeling. The accurate singing of musical intervals requires communication between auditory feedback processing and vocal motor control (i.e. audio-vocal integration) to ensure that each note is produced correctly. The objective of this study is to investigate the neural mechanisms through which trained musicians produce consonant and dissonant intervals. We utilized 4 musical intervals (specifically, an octave, a major seventh, a fifth, and a tritone) as the main stimuli for auditory discrimination testing, and we used the same interval tasks to assess vocal accuracy in a group of musicians (11 subjects, all female vocal students at conservatory level). The intervals were chosen so as to test for differences in recognition and production of consonant and dissonant intervals, as well as narrow and wide intervals. The subjects were studied using fMRI during performance of the interval tasks; the control condition consisted of passive listening. Singing dissonant intervals as opposed to singing consonant intervals led to an increase in activation in several regions, most notably the primary auditory cortex, the primary somatosensory cortex, the amygdala, the left putamen, and the right insula. Singing wide intervals as opposed to singing narrow intervals resulted in the activation of the right anterior insula. Moreover, we also observed a correlation between singing in tune and brain activity in the premotor cortex, and a positive correlation between training and activation of primary somatosensory cortex, primary motor cortex, and premotor cortex during singing. When singing dissonant intervals, a higher degree of training correlated with the right thalamus and the left putamen. Our results indicate that singing dissonant intervals requires greater involvement of neural mechanisms associated with integrating external feedback from auditory and sensorimotor systems than singing consonant intervals, and it would then seem likely that dissonant intervals are intoned by adjusting the neural mechanisms used for the production of consonant intervals. Singing wide intervals requires a greater degree of control than singing narrow intervals, as it involves neural mechanisms which again involve the integration of internal and external feedback. Copyright © 2016 Elsevier B.V. All rights reserved.

Psychophysics of remembering.

PubMed Central

White, K G; Wixted, J T

1999-01-01

We present a new model of remembering in the context of conditional discrimination. For procedures such as delayed matching to sample, the effect of the sample stimuli at the time of remembering is represented by a pair of Thurstonian (normal) distributions of effective stimulus values. The critical assumption of the model is that, based on prior experience, each effective stimulus value is associated with a ratio of reinforcers obtained for previous correct choices of the comparison stimuli. That ratio determines the choice that is made on the basis of the matching law. The standard deviations of the distributions are assumed to increase with increasing retention-interval duration, and the distance between their means is assumed to be a function of other factors that influence overall difficulty of the discrimination. It is a behavioral model in that choice is determined by its reinforcement history. The model predicts that the biasing effects of the reinforcer differential increase with decreasing discriminability and with increasing retention-interval duration. Data from several conditions using a delayed matching-to-sample procedure with pigeons support the predictions. PMID:10028693

Perceived discrimination and smoking among rural-to-urban migrant women in China.

PubMed

Shin, Sanghyuk S; Wan, Xia; Wang, Qian; Raymond, H Fisher; Liu, Huilin; Ding, Ding; Yang, Gonghuan; Novotny, Thomas E

2013-02-01

Smoking may be a coping mechanism for psychosocial stress caused by discrimination. We conducted a cross-sectional survey of rural-to-urban migrant women working as restaurant/hotel workers (RHWs) and those working as sex workers (FSWs) in 10 Chinese cities to investigate whether perceived discrimination is associated with smoking. We interviewed RHWs at medical examination clinics and FSWs at entertainment venues. Modified Poisson regression was used to estimate prevalence ratios. Of the 1,696 RHWs and 532 FSWs enrolled, 155 (9.1%) and 63 (11.8%) reported perceived discrimination, respectively. Perceived discrimination was independently associated with ever tried smoking (prevalence ratio [PR], 1.71; 95% confidence interval [CI], 1.31-2.23) and current smoking (PR, 2.52; 95% CI, 1.32-4.79) among RHWs and ever tried smoking (PR, 1.36; 95% CI, 1.16-1.61) and current smoking (PR, 1.63; 95% CI, 1.28-2.06) among FSWs. Perceived discrimination is associated with higher prevalence of smoking among rural-to-urban migrant women in China.

The relationship between discrimination and substance use disorders among lesbian, gay, and bisexual adults in the United States.

PubMed

McCabe, Sean Esteban; Bostwick, Wendy B; Hughes, Tonda L; West, Brady T; Boyd, Carol J

2010-10-01

We examined the associations between 3 types of discrimination (sexual orientation, race, and gender) and substance use disorders in a large national sample in the United States that included 577 lesbian, gay, and bisexual (LGB) adults. Data were collected from wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions, which used structured diagnostic face-to-face interviews. More than two thirds of LGB adults reported at least 1 type of discrimination in their lifetimes. Multivariate analyses indicated that the odds of past-year substance use disorders were nearly 4 times greater among LGB adults who reported all 3 types of discrimination prior to the past year than for LGB adults who did not report discrimination (adjusted odds ratio = 3.85; 95% confidence interval = 1.71, 8.66). Health professionals should consider the role multiple types of discrimination plays in the development and treatment of substance use disorders among LGB adults.

Olfactory discrimination and memory deficits in the Flinders Sensitive Line rodent model of depression.

PubMed

Cook, A; Pfeiffer, L-M; Thiele, S; Coenen, V A; Döbrössy, M D

2017-10-01

Major Depressive Disorder (MDD) is a heterogeneous psychiatric disorder with broad symptomatic manifestations. The current study examined, for the first time, olfactory memory and discrimination in the Flinders Sensitive Line (FSL) rodent model of depression. Male FSL rats and controls were trained on an Olfactory Discrimination (OD) and a Social Interaction (SI) test. On the OD test, the FSL and controls performed similarly at the shortest inter-trial interval (5min), however, with extended delay of 30min, the FSLs had a recall and odour discrimination deficit. At the longest delay (60min) both groups performed poorly. The FSL rats i.) had a deficit in olfactory discrimination suggesting impairment in olfactory memory and recall; ii.) were less likely to socialize with unfamiliar rats. The data suggests that FSL animals have an impaired olfactory information processing capacity. Copyright © 2017 Elsevier B.V. All rights reserved.

Sleep-dependent consolidation benefits fast transfer of time interval training.

PubMed

Chen, Lihan; Guo, Lu; Bao, Ming

2017-03-01

Previous study has shown that short training (15 min) for explicitly discriminating temporal intervals between two paired auditory beeps, or between two paired tactile taps, can significantly improve observers' ability to classify the perceptual states of visual Ternus apparent motion while the training of task-irrelevant sensory properties did not help to improve visual timing (Chen and Zhou in Exp Brain Res 232(6):1855-1864, 2014). The present study examined the role of 'consolidation' after training of temporal task-irrelevant properties, or whether a pure delay (i.e., blank consolidation) following pretest of the target task would give rise to improved ability of visual interval timing, typified in visual Ternus display. A procedure of pretest-training-posttest was adopted, with the probe of discriminating Ternus apparent motion. The extended implicit training of timing in which the time intervals between paired auditory beeps or paired tactile taps were manipulated but the task was discrimination of the auditory pitches or tactile intensities, did not lead to the training benefits (Exps 1 and 3); however, a delay of 24 h after implicit training of timing, including solving 'Sudoku puzzles,' made the otherwise absent training benefits observable (Exps 2, 4, 5 and 6). The above improvements in performance were not due to a practice effect of Ternus motion (Exp 7). A general 'blank' consolidation period of 24 h also made improvements of visual timing observable (Exp 8). Taken together, the current findings indicated that sleep-dependent consolidation imposed a general effect, by potentially triggering and maintaining neuroplastic changes in the intrinsic (timing) network to enhance the ability of time perception.

Cortical Plasticity Induction by Pairing Subthalamic Nucleus Deep-Brain Stimulation and Primary Motor Cortical Transcranial Magnetic Stimulation in Parkinson's Disease.

PubMed

Udupa, Kaviraja; Bahl, Nina; Ni, Zhen; Gunraj, Carolyn; Mazzella, Filomena; Moro, Elena; Hodaie, Mojgan; Lozano, Andres M; Lang, Anthony E; Chen, Robert

2016-01-13

Noninvasive brain stimulation studies have shown abnormal motor cortical plasticity in Parkinson's disease (PD). These studies used peripheral nerve stimulation paired with transcranial magnetic stimulation (TMS) to primary motor cortex (M1) at specific intervals to induce plasticity. Induction of cortical plasticity through stimulation of the basal ganglia (BG)-M1 connections has not been studied. In the present study, we used a novel technique of plasticity induction by repeated pairing of deep-brain stimulation (DBS) of the BG with M1 stimulation using TMS. We hypothesize that repeated pairing of subthalamic nucleus (STN)-DBS and M1-TMS at specific time intervals will lead to plasticity in the M1. Ten PD human patients with STN-DBS were studied in the on-medication state with DBS set to 3 Hz. The interstimulus intervals (ISIs) between STN-DBS and TMS that produced cortical facilitation were determined individually for each patient. Three plasticity induction conditions with repeated pairings (180 times) at specific ISIs (∼ 3 and ∼ 23 ms) that produced cortical facilitation and a control ISI of 167 ms were tested in random order. Repeated pairing of STN-DBS and M1-TMS at short (∼ 3 ms) and medium (∼ 23 ms) latencies increased M1 excitability that lasted for at least 45 min, whereas the control condition (fixed ISI of 167 ms) had no effect. There were no specific changes in motor thresholds, intracortical circuits, or recruitment curves. Our results indicate that paired-associative cortical plasticity can be induced by repeated STN and M1 stimulation at specific intervals. These results show that STN-DBS can modulate cortical plasticity. We introduced a new experimental paradigm to test the hypothesis that pairing subthalamic nucleus deep-brain stimulation (STN-DBS) with motor cortical transcranial magnetic stimulation (M1-TMS) at specific times can induce cortical plasticity in patients with Parkinson's disease (PD). We found that repeated pairing of STN-DBS with TMS at short (∼ 3 ms) and medium (∼ 23 ms) intervals increased cortical excitability that lasted for up to 45 min, whereas the control condition (fixed latency of 167 ms) had no effects on cortical excitability. This is the first demonstration of associative plasticity in the STN-M1 circuits in PD patients using this novel technique. The potential therapeutic effects of combining DBS and noninvasive cortical stimulation should be investigated further. Copyright © 2016 the authors 0270-6474/16/360397-09$15.00/0.

Discrimination of curvature from motion during smooth pursuit eye movements and fixation.

PubMed

Ross, Nicholas M; Goettker, Alexander; Schütz, Alexander C; Braun, Doris I; Gegenfurtner, Karl R

2017-09-01

Smooth pursuit and motion perception have mainly been investigated with stimuli moving along linear trajectories. Here we studied the quality of pursuit movements to curved motion trajectories in human observers and examined whether the pursuit responses would be sensitive enough to discriminate various degrees of curvature. In a two-interval forced-choice task subjects pursued a Gaussian blob moving along a curved trajectory and then indicated in which interval the curve was flatter. We also measured discrimination thresholds for the same curvatures during fixation. Motion curvature had some specific effects on smooth pursuit properties: trajectories with larger amounts of curvature elicited lower open-loop acceleration, lower pursuit gain, and larger catch-up saccades compared with less curved trajectories. Initially, target motion curvatures were underestimated; however, ∼300 ms after pursuit onset pursuit responses closely matched the actual curved trajectory. We calculated perceptual thresholds for curvature discrimination, which were on the order of 1.5 degrees of visual angle (°) for a 7.9° curvature standard. Oculometric sensitivity to curvature discrimination based on the whole pursuit trajectory was quite similar to perceptual performance. Oculometric thresholds based on smaller time windows were higher. Thus smooth pursuit can quite accurately follow moving targets with curved trajectories, but temporal integration over longer periods is necessary to reach perceptual thresholds for curvature discrimination. NEW & NOTEWORTHY Even though motion trajectories in the real world are frequently curved, most studies of smooth pursuit and motion perception have investigated linear motion. We show that pursuit initially underestimates the curvature of target motion and is able to reproduce the target curvature ∼300 ms after pursuit onset. Temporal integration of target motion over longer periods is necessary for pursuit to reach the level of precision found in perceptual discrimination of curvature. Copyright © 2017 the American Physiological Society.

Grand average ERP-image plotting and statistics: A method for comparing variability in event-related single-trial EEG activities across subjects and conditions

PubMed Central

Delorme, Arnaud; Miyakoshi, Makoto; Jung, Tzyy-Ping; Makeig, Scott

2014-01-01

With the advent of modern computing methods, modeling trial-to-trial variability in biophysical recordings including electroencephalography (EEG) has become of increasingly interest. Yet no widely used method exists for comparing variability in ordered collections of single-trial data epochs across conditions and subjects. We have developed a method based on an ERP-image visualization tool in which potential, spectral power, or some other measure at each time point in a set of event-related single-trial data epochs are represented as color coded horizontal lines that are then stacked to form a 2-D colored image. Moving-window smoothing across trial epochs can make otherwise hidden event-related features in the data more perceptible. Stacking trials in different orders, for example ordered by subject reaction time, by context-related information such as inter-stimulus interval, or some other characteristic of the data (e.g., latency-window mean power or phase of some EEG source) can reveal aspects of the multifold complexities of trial-to-trial EEG data variability. This study demonstrates new methods for computing and visualizing grand ERP-image plots across subjects and for performing robust statistical testing on the resulting images. These methods have been implemented and made freely available in the EEGLAB signal-processing environment that we maintain and distribute. PMID:25447029

The role of iconic memory in change-detection tasks.

PubMed

Becker, M W; Pashler, H; Anstis, S M

2000-01-01

In three experiments, subjects attempted to detect the change of a single item in a visually presented array of items. Subjects' ability to detect a change was greatly reduced if a blank interstimulus interval (ISI) was inserted between the original array and an array in which one item had changed ('change blindness'). However, change detection improved when the location of the change was cued during the blank ISI. This suggests that people represent more information of a scene than change blindness might suggest. We test two possible hypotheses why, in the absence of a cue, this representation fails to produce good change detection. The first claims that the intervening events employed to create change blindness result in multiple neural transients which co-occur with the to-be-detected change. Poor detection rates occur because a serial search of all the transient locations is required to detect the change, during which time the representation of the original scene fades. The second claims that the occurrence of the second frame overwrites the representation of the first frame, unless that information is insulated against overwriting by attention. The results support the second hypothesis. We conclude that people may have a fairly rich visual representation of a scene while the scene is present, but fail to detect changes because they lack the ability to simultaneously represent two complete visual representations.

Neonatal and fetal response decrement of evoked responses – a MEG study

PubMed Central

Sheridan, Carolin J.; Preissl, Hubert; Siegel, Eric R.; Murphy, Pam; Ware, Maureen; Lowery, Curtis L.; Eswaran, Hari

2008-01-01

Objective To investigate the response decrements of visual evoked responses (VER) in newborns and assess the applicability of this paradigm to fetuses in magnetoencephalographic (MEG) recordings. Methods Twelve newborns with no known risks or complications participated at chronological ages between six and 22 days. They constituted the follow-up group to a prenatal study conducted on a sample of 25 fetuses whose gestational age (GA) varied between 29 and 37 weeks at the time of recording. Trains of four light flashes with an interstimulus interval of 2 s followed by 10 s without stimulation were delivered to record VER. Results Nine of the 12 newborns responded to the stimulation and showed response decrements in amplitude from the first to the last light flash. Furthermore, the response latency increased significantly from the first to the last stimulus. The remaining three recordings were discontinued early. Even though the prenatal visual evoked response rate was only 29%, the fetuses exhibited a response decrement after the first stimulus. Conclusions The amplitude of VERs can be used to elicit a response decrement in newborns and, with limitations, even in fetuses. This paradigm might be a useful tool for a direct non-invasive assessment of neonatal and prenatal brain development and CNS functioning. Significance The proposed method might be a first step towards an early detection of developmental deficits in newborns and fetuses. PMID:18226946

Effects of Passive Finger Movement on Cortical Excitability

PubMed Central

Nakagawa, Masaki; Sasaki, Ryoki; Tsuiki, Shota; Miyaguchi, Shota; Kojima, Sho; Saito, Kei; Inukai, Yasuto; Onishi, Hideaki

2017-01-01

This study examined the effects of joint angle and passive movement direction on corticospinal excitability. The subjects were 14 healthy adults from whom consent could be obtained. We performed two experiments. In Experiment 1, we measured motor evoked potential (MEP) amplitude, F-wave and M-wave at 0° and 20° adduction during adduction or abduction movement, in the range of movement from 10° abduction to 30° adduction. In Experiment 2, MEPs were measured at static 0° and 20° adduction during passive adduction from 10° adduction to 30° adduction and static 20° adduction. MEP, F-waves and M-waves were recorded from the right first dorsal interosseous (FDI) muscle. Experiment 1 revealed significantly increased MEP amplitude at 0° during passive adduction compared to static 0° (p < 0.01). No other significant differences in MEP, M-wave and F-wave parameters were observed. In Experiment 2, MEP amplitude was significantly higher at 20° adduction during passive adduction compared with static 0° (p < 0.01). Based on these findings, it appears that fluctuations in MEP amplitude values during passive movement are not influenced by joint angle, but rather it is possible that it is due to intracortical afferent facilitation (AF) dependent on afferent input due to the start of movement and interstimulus interval (ISI) of transcranial magnetic stimulation (TMS). PMID:28515687

Normalization of sensorimotor integration by repetitive transcranial magnetic stimulation in cervical dystonia.

PubMed

Zittel, S; Helmich, R C; Demiralay, C; Münchau, A; Bäumer, T

2015-08-01

Previous studies indicated that sensorimotor integration and plasticity of the sensorimotor system are impaired in dystonia patients. We investigated motor evoked potential amplitudes and short latency afferent inhibition to examine corticospinal excitability and cortical sensorimotor integration, before and after inhibitory 1 Hz repetitive transcranial magnetic stimulation over primary sensory and primary motor cortex in patients with cervical dystonia (n = 12). Motor evoked potentials were recorded from the right first dorsal interosseous muscle after application of unconditioned transcranial magnetic test stimuli and after previous conditioning electrical stimulation of the right index finger at short interstimulus intervals of 25, 30 and 40 ms. Results were compared to a group of healthy age-matched controls. At baseline, motor evoked potential amplitudes did not differ between groups. Short latency afferent inhibition was reduced in cervical dystonia patients compared to healthy controls. Inhibitory 1 Hz sensory cortex repetitive transcranial magnetic stimulation but not motor cortex repetitive transcranial magnetic stimulation increased motor evoked potential amplitudes in cervical dystonia patients. Additionally, both 1 Hz repetitive transcranial magnetic stimulation over primary sensory and primary motor cortex normalized short latency afferent inhibition in these patients. In healthy subjects, sensory repetitive transcranial magnetic stimulation had no influence on motor evoked potential amplitudes and short latency afferent inhibition. Plasticity of sensorimotor circuits is altered in cervical dystonia patients.

Goal neglect, fluid intelligence and processing speed: Manipulating instruction load and inter-stimulus interval.

PubMed

Iveson, Matthew H; Della Sala, Sergio; Anderson, Mike; MacPherson, Sarah E

2017-05-01

Goal maintenance is the process where task rules and instructions are kept active to exert their control on behavior. When this process fails, an individual may ignore a rule while performing the task, despite being able to describe it after task completion. Previous research has suggested that the goal maintenance system is limited by the number of concurrent rules which can be maintained during a task, and that this limit is dependent on an individual's level of fluid intelligence. However, the speed at which an individual can process information may also limit their ability to use task rules when the task demands them. In the present study, four experiments manipulated the number of instructions to be maintained by younger and older adults and examined whether performance on a rapid letter-monitoring task was predicted by individual differences in fluid intelligence or processing speed. Fluid intelligence played little role in determining how frequently rules were ignored during the task, regardless of the number of rules to be maintained. In contrast, processing speed predicted the rate of goal neglect in older adults, where increasing the presentation rate of the letter-monitoring task increased goal neglect. These findings suggest that goal maintenance may be limited by the speed at which it can operate. Copyright © 2017. Published by Elsevier B.V.

Abnormal experimentally- and behaviorally-induced LTP-like plasticity in focal hand dystonia.

PubMed

Belvisi, Daniele; Suppa, Antonio; Marsili, Luca; Di Stasio, Flavio; Parvez, Ahmad Khandker; Agostino, Rocco; Fabbrini, Giovanni; Berardelli, Alfredo

2013-02-01

Idiopathic focal hand dystonia (FHD) arises from abnormal plasticity in the primary motor cortex (M1) possibly reflecting abnormal sensori-motor integration processes. In this transcranial magnetic stimulation (TMS) study in FHD, we evaluated changes in motor evoked potentials (MEPs) after intermittent theta burst stimulation (iTBS) and paired associative stimulation (PAS), techniques that elicit different forms of experimentally-induced long-term potentiation (LTP)-like plasticity in M1. We also examined behaviorally-induced LTP-like plasticity as reflected by early motor learning of a simple motor task. We studied 14 patients with FHD and 14 healthy subjects. MEPs were recorded before and after iTBS and PAS at the 25 ms interstimulus interval (PAS(25)) in separate sessions. Subjects did a simple motor task entailing repetitive index finger abductions. To measure early motor learning we tested practice-related improvement in peak velocity and peak acceleration. In FHD patients iTBS failed to elicit the expected MEP changes and PAS(25) induced abnormally increased MEPs in target and non-target muscles. In the experiment testing early motor learning, patients lacked the expected practice-related changes in kinematic variables. In FHD, the degree of early motor learning correlated with patients' clinical features. We conclude that experimentally-induced (iTBS and PAS) and behaviorally-induced LTP-like plasticity are both altered in FHD. Copyright © 2012 Elsevier Inc. All rights reserved.

Different SEP recovery cycle in adolescent migraineurs with exploding or imploding pain.

PubMed

Iacovelli, Elisa; Tarantino, Samuela; Capuano, Alessandro; De Luca, Massimiliano; De Ranieri, Cristiana; Vigevano, Federico; Arendt-Nielsen, Lars; Valeriani, Massimiliano

2013-01-01

Our aim was to investigate whether migraine adolescents with pain directed inside (imploding pain--IP) and outside (exploding pain--EP) the head may have different levels of cortical excitability underlying their migraineous syndrome. Ten migraine children referring prevalent EP (mean age 14.5 ± 1.4 years, 3 girls, 7 boys), 10 patients with IP (mean age 14.1 ± 2.2 years, 4 girls, 6 boys), and 13 control subjects (mean age 13 ± 1.8 years, 6 males, 7 females) participated to the study. The recovery cycle of the somatosensory evoked potentials to electrical median nerve stimuli at interstimulus intervals of 5, 20, and 40 ms was measured. Anger expression, anxiety, and somatic concerns were investigated in migraine patients. Overall, SEP recovery cycle was shorter in migraineurs than in healthy controls. The recovery cycle of the frontal N30 SEP component was significantly shorter in IP than in EP patients. While among the EP patients those with faster N30 recovery cycle had higher Trait-Anger score, the opposite was found among the IP patients. Our results suggest that the inhibitory mechanisms within the somatosensory cortex are more impaired in IP than in EP migraine adolescents. The pathophysiological difference between IP and EP migraineurs was strengthened also by the opposite correlations between the brain excitability and the anger expression. Copyright © 2013 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Encoding vs. retention: differential effects of cue manipulation on working memory performance in schizophrenia.

PubMed

Javitt, Daniel C; Rabinowicz, Esther; Silipo, Gail; Dias, Elisa C

2007-03-01

Deficits in working memory performance are among the most widely replicated findings in schizophrenia. Roles of encoding vs. memory retention in working memory remain unresolved. The present study evaluated working memory performance in schizophrenia using an AX-type continuous performance test (AX-CPT) paradigm. Participants included 48 subjects with schizophrenia and 27 comparison subjects. Behavior was obtained in 3 versions of the task, which differed based upon ease of cue interoperability. In a simple cue version of the task, cue letters were replaced with red or green circles. In the complex cue version, letter/color conjunctions served as cues. In the base version of the task, patients showed increased rates of false alarms to invalidly cued targets, similar to prior reports. However, when the cue stimuli were replaced with green or red circles to ease interpretation, patients showed similar false alarm rates to controls. When feature conjunction cues were used, patients were also disproportionately affected relative to controls. No significant group by interstimulus interval interaction effects were observed in either the simple or complex cue conditions, suggesting normal retention of information even in the presence of overall performance decrements. These findings suggest first, that cue manipulation disproportionately affects AX-CPT performance in schizophrenia and, second, that substantial behavioral deficits may be observed on working memory tasks even in the absence of disturbances in mnemonic retention.

Side Effects of Being Blue: Influence of Sad Mood on Visual Statistical Learning

PubMed Central

Bertels, Julie; Demoulin, Catherine; Franco, Ana; Destrebecqz, Arnaud

2013-01-01

It is well established that mood influences many cognitive processes, such as learning and executive functions. Although statistical learning is assumed to be part of our daily life, as mood does, the influence of mood on statistical learning has never been investigated before. In the present study, a sad vs. neutral mood was induced to the participants through the listening of stories while they were exposed to a stream of visual shapes made up of the repeated presentation of four triplets, namely sequences of three shapes presented in a fixed order. Given that the inter-stimulus interval was held constant within and between triplets, the only cues available for triplet segmentation were the transitional probabilities between shapes. Direct and indirect measures of learning taken either immediately or 20 minutes after the exposure/mood induction phase revealed that participants learned the statistical regularities between shapes. Interestingly, although participants from the sad and neutral groups performed similarly in these tasks, subjective measures (confidence judgments taken after each trial) revealed that participants who experienced the sad mood induction showed increased conscious access to their statistical knowledge. These effects were not modulated by the time delay between the exposure/mood induction and the test phases. These results are discussed within the scope of the robustness principle and the influence of negative affects on processing style. PMID:23555797

Overcoming residual interference in mental set switching: Neural correlates and developmental trajectory

PubMed Central

Witt, Suzanne T.; Stevens, Michael C.

2012-01-01

Mental set switching is a key facet of executive control measured behaviorally through reaction time or accuracy (i.e., ‘switch costs’) when shifting among task types. One of several experimentally-dissociable influences on switch costs is ‘task set inertia’, conceptualized as the residual interference conferred when a previous stimulus-response tendency interferes with subsequent stimulus processing on a new task. Task set inertia is thought to represent the passive decay of the previous stimulus-response set from working memory, and its effects decrease with increased interstimulus interval. Closely spaced trials confer high task set inertia, while sparsely spaced trials confer low task set inertia. This functional magnetic resonance imaging (fMRI) study characterized, for the first time, two opposing brain systems engaged to resolve task set inertia: 1) a frontoparietal ‘cortical control’ network for overcoming high task set inertia interference and 2) a subcortical-motor network more active during trials with low task set inertia. These networks were distinct from brain regions showing general switching effects (i.e., switch > non-switch) and from other previously-characterized interference effects. Moreover, there were ongoing maturational effects throughout adolescence for the brain regions engaged to overcome high task set inertia not seen for generalized switching effects. These novel findings represent a new avenue of exploration of cognitive set switching neural function. PMID:22584223

Temporal masking of multidimensional tactual stimuli

NASA Astrophysics Data System (ADS)

Tan, Hong Z.; Reed, Charlotte M.; Delhorne, Lorraine A.; Durlach, Nathaniel I.; Wan, Natasha

2003-12-01

Experiments were performed to examine the temporal masking properties of multidimensional tactual stimulation patterns delivered to the left index finger. The stimuli consisted of fixed-frequency sinusoidal motions in the kinesthetic (2 or 4 Hz), midfrequency (30 Hz), and cutaneous (300 Hz) frequency ranges. Seven stimuli composed of one, two, or three spectral components were constructed at each of two signal durations (125 or 250 ms). Subjects identified target signals under three different masking paradigms: forward masking, backward masking, and sandwiched masking (in which the target is presented between two maskers). Target identification was studied as a function of interstimulus interval (ISI) in the range 0 to 640 ms. For both signal durations, percent-correct scores increased with ISI for each of the three masking paradigms. Scores with forward and backward masking were similar and significantly higher than scores obtained with sandwiched masking. Analyses of error trials revealed that subjects showed a tendency to respond, more often than chance, with the masker, the composite of the masker and target, or the combination of the target and a component of the masker. The current results are compared to those obtained in previous studies of tactual recognition masking with brief cutaneous spatial patterns. The results are also discussed in terms of estimates of information transfer (IT) and IT rate, are compared to previous studies with multidimensional tactual signals, and are related to research on the development of tactual aids for the deaf.

Central nervous system abnormalities in vaginismus.

PubMed

Frasson, Emma; Graziottin, Alessandra; Priori, Alberto; Dall'ora, Elisa; Didonè, Giuseppe; Garbin, Emilio Luigi; Vicentini, Silvana; Bertolasi, Laura

2009-01-01

To investigate possible altered CNS excitability in vaginismus. In 10 patients with primary idiopathic lifelong vaginismus, 10 with vulvar vestibulitis syndrome accompanied by vaginismus and healthy controls we recorded EMG activity from the levator ani (LA) and external anal sphincter (EAS) muscles and tested bulbocavernosus reflex (BCR). Pudendal-nerve somatosensory evoked potentials (SEPs) were tested after a single stimulus. Pudendal-nerve SEP recovery functions were assessed using a paired conditioning-test paradigm at interstimulus intervals (ISIs) of 5, 20 and 40ms. EMG in patients showed muscular hyperactivity at rest and reduced inhibition during straining. The BCR polysynaptic R2 had larger amplitude (p<0.01) and longer duration (p<0.01) in patients from both groups than in controls. In controls, paired-pulse SEPs were suppressed at the 5ms ISI for N35-P40 (p<0.05) and P40-N50 ms (p<0.001) and facilitated at the 20ms ISI for N35-P40 (p<0.05) and P40-N50 (p<0.05). No significant differences were found in the paired-pulse N35-P40 in patients and controls but the cortical P40-N50 at 20 ISI was facilitated in patients (p<0.05). EMG activity is enhanced and the cortical SEP recovery cycle and BCR are hyperexcitable in vaginismus. The neurophysiological abnormalities in patients with vaginismus indicate concomitant CNS changes in this disorder.

Two forms of persistence in visual information processing.

PubMed

Di Lollo, Vincent; Dixon, Peter

1988-11-01

Iconic memory, which was initially regarded as a unitary phenomenon, has since been subdivided into several components. In the present work we examined the joint effects of two such components (visible persistence and the visual analog representation) on performance in a partial report task. The display consisted of 15 alphabetic characters arranged around the perimeter of an imaginary circle on the face of an oscilloscope. The observer named the character singled out by a bar-probe. Two factors were varied: exposure duration of the array (10, 50, 100, 150, 200, 300, 400 or 500 ms) and duration of blank period (interstimulus interval, ISI) between the termination of the array and the onset of the probe (0, 50, 100, 150, or 200 ms). Performance was progressively impaired as both exposure duration and ISI were increased. The results were explained in terms of a probabilistic combinatorial model in which the timecourses of visible persistence and of the visual analog representation are regarded as time-locked to the onset and to the end of stimulation, respectively. The impairing effect of exposure duration was attributed to the relatively high spatial demands of the task that could be met optimally by information in visible persistence (which declines as a function of exposure duration), but less adequately by information in the visual analog representation. A second experiment, employing a task with lesser spatial demands, confirmed this interpretation.

Impaired semantic inhibition during lexical ambiguity repetition in Parkinson's disease.

PubMed

Copland, David A; Sefe, Gameli; Ashley, Jane; Hudson, Carrie; Chenery, Helen J

2009-09-01

Impairments of semantic processing and inhibition have been observed in Parkinson's disease (PD), however, the consequences of faulty meaning selection and suppression have not been considered in terms of subsequent lexical processing. The present study employed a lexical ambiguity repetition paradigm where the first presentation of an ambiguity paired with a target biasing its dominant or subordinate meaning (e.g., bank - money or bank - river) was followed after several intervening trials by a presentation of the same ambiguity paired with a different target that biases the same (congruent) or a different (incongruent) meaning to that biased on the first presentation. Meaning dominance (dominant or subordinate weaker meanings) and interstimulus interval (ISI) were manipulated. Analyses conducted on the second presentation indicated priming of congruent meanings and no priming for the incongruent meanings at both short and long ISIs in the healthy controls, consistent with suppression of meanings competing with the representation biased in the first presentation. In contrast, the PD group failed to dampen activation for the incongruent meaning at the long ISI when the first presentation was subordinate. This pattern is consistent with an impairment of meaning suppression which is observed under controlled processing conditions and varies as a function of meaning dominance of the first presentation. These findings further refine our understanding of lexical-semantic impairments in PD and suggest a mechanism that may contribute to discourse comprehension impairments in this population.

Tremor pattern differentiates drug-induced resting tremor from Parkinson disease.

PubMed

Nisticò, R; Fratto, A; Vescio, B; Arabia, G; Sciacca, G; Morelli, M; Labate, A; Salsone, M; Novellino, F; Nicoletti, A; Petralia, A; Gambardella, A; Zappia, M; Quattrone, A

2016-04-01

DAT-SPECT, is a well-established procedure for distinguishing drug-induced parkinsonism from Parkinson's disease (PD). We investigated the usefulness of blink reflex recovery cycle (BRrc) and of electromyographic parameters of resting tremor for the differentiation of patients with drug-induced parkinsonism with resting tremor (rDIP) from those with resting tremor due to PD. This was a cross-sectional study. In 16 patients with rDIP and 18 patients with PD we analysed electrophysiological parameters (amplitude, duration, burst and pattern) of resting tremor. BRrc at interstimulus intervals (ISI) of 100, 150, 200, 300, 400, 500 and 750 msec was also analysed in patients with rDIP, patients with PD and healthy controls. All patients and controls underwent DAT-SPECT. Rest tremor amplitude was higher in PD patients than in rDIP patients (p < 0.001), while frequency and burst duration were higher in rDIP than in PD (p < 0.001, p < 0.003, respectively). Resting tremor showed a synchronous pattern in all patients with rDIP, whereas it had an alternating pattern in all PD patients (p < 0.001). DAT-SPECT was normal in rDIP patients while it was markedly abnormal in patients with PD. In the absence of DAT-SPECT, the pattern of resting tremor can be considered a useful investigation for differentiating rDIP from PD. Copyright © 2016. Published by Elsevier Ltd.

Schedule-induced masseter EMG in facial pain subjects vs. no-pain controls.

PubMed

Gramling, S E; Grayson, R L; Sullivan, T N; Schwartz, S

1997-02-01

Empirical reports suggest that oral habits (e.g., teeth clenching) may be behavioral mediators linking stress to muscle hyperreactivity and the development of facial pain. Another report suggests that excessive behavioral adjuncts develop in conjunction with fixed-time stimulus presentation. The present study assessed the extent to which the oral habits exhibited by facial pain patients are schedule-induced. Subjects with Temporomandibular Disorder (TMD) symptomatology (n = 15) and pain-free controls (n = 15) participated in a 4-phase experiment (adaptation, baseline, task, recovery) designed to elicit schedule-induced behaviors. Self-report of oral habits and negative affect were recorded after each phase. Objective measures of oral habits were obtained via behavioral observation and masseter EMG recordings. Results revealed that negative arousal significantly increased during the fixed-time (FT) task and was also associated with increased oral habits among the TMD subjects. Moreover, 40% of the TMD subjects and none of the controls exhibited a pattern of EMG elevations in the early part of the inter-stimulus interval that met a strict criteria for scheduled-induced behavior per se. Taken together, these results suggest that the TMD subjects were engaging in schedule-induced oral habits. The adjunctive behavior literature seems to provide a plausible explanation as to how oral habits develop and are maintained in TMD patients, despite their painful consequences.

Intra-individual reaction time variability based on ex-Gaussian distribution as a potential endophenotype for attention-deficit/hyperactivity disorder.

PubMed

Lin, H-Y; Hwang-Gu, S-L; Gau, S S-F

2015-07-01

Intra-individual variability in reaction time (IIV-RT), defined by standard deviation of RT (RTSD), is considered as an endophenotype for attention-deficit/hyperactivity disorder (ADHD). Ex-Gaussian distributions of RT, rather than RTSD, could better characterize moment-to-moment fluctuations in neuropsychological performance. However, data of response variability based on ex-Gaussian parameters as an endophenotypic candidate for ADHD are lacking. We assessed 411 adolescents with clinically diagnosed ADHD based on the DSM-IV-TR criteria as probands, 138 unaffected siblings, and 138 healthy controls. The output parameters, mu, sigma, and tau, of an ex-Gaussian RT distribution were derived from the Conners' continuous performance test. Multi-level models controlling for sex, age, comorbidity, and use of methylphenidate were applied. Compared with unaffected siblings and controls, ADHD probands had elevated sigma value, omissions, commissions, and mean RT. Unaffected siblings formed an intermediate group in-between probands and controls in terms of tau value and RTSD. There was no between-group difference in mu value. Conforming to a context-dependent nature, unaffected siblings still had an intermediate tau value in-between probands and controls across different interstimulus intervals. Our findings suggest IIV-RT represented by tau may be a potential endophenotype for inquiry into genetic underpinnings of ADHD in the context of heterogeneity. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Repetitive muscle compression reduces vascular mechano-sensitivity and the hyperemic response to muscle contraction.

PubMed

Messere, A; Turturici, M; Millo, G; Roatta, S

2017-06-01

Animal studies have shown that the rapid hyperemic response to external muscle compression undergoes inactivation upon repetitive stimulation, but this phenomenon has never been observed in humans. The aim of the present study was to determine whether 1) the vascular mechano-sensitivity underlying muscle compression-induced hyperemia is inactivated in an inter-stimulus interval (ISI)-dependent fashion upon repetitive stimulation, as suggested by animal studies, and 2) whether such inactivation also attenuates contraction-induced hyperemia. Brachial artery blood flow was measured by echo Doppler sonography in 13 healthy adults in response to 1) single and repetitive cuff muscle compression (CMC) of the forearm (20 CMCs, 1 s ISI); 2) a sequence of CMC delivered at decreasing ISI from 120 to 2 s; and 3) electrically-stimulated contraction of the forearm muscles before and after repetitive CMC. The peak amplitude of hyperemia in response to CMC normalized to baseline decreased from 2.2 ± 0.6 to 1.4 ± 0.4 after repetitive CMC and, in general, was decreased at ISI < 240 s. The peak amplitude of contraction-induced hyperemia was attenuated after as compared to before repeated CMC (1.7 ± 0.4 and 2.6 ± 0.6, respectively). Mechano-sensitivity of the vascular network can be conditioned by previous mechanical stimulation, and such preconditioning may substantially decrease contraction-induced hyperemia.

Exposure to Discrimination and Heart Rate Variability Reactivity to Acute Stress among Women with Diabetes.

PubMed

Wagner, Julie; Lampert, Rachel; Tennen, Howard; Feinn, Richard

2015-08-01

Exposure to racial discrimination has been linked to physiological reactivity. This study investigated self-reported exposure to racial discrimination and parasympathetic [high-frequency heart rate variability (HF-HRV)] and sympathetic (norepinephrine and cortisol) activity at baseline and then again after acute laboratory stress. Lifetime exposure to racial discrimination was measured with the Schedule of Racist Events scale. Thirty-two women (16 Black and 16 White) with type 2 diabetes performed a public speaking stressor. Beat-to-beat intervals were recorded on electrocardiograph recorders, and HF-HRV was calculated using spectral analysis and natural log transformed. Norepinephrine and cortisol were measured in blood. Higher discrimination predicted lower stressor HF-HRV, even after controlling for baseline HF-HRV. When race, age, A1c and baseline systolic blood pressure were also controlled, racial discrimination remained a significant independent predictor of stressor HF-HRV. There was no association between lifetime discrimination and sympathetic markers. In conclusion, preliminary data suggest that among women with type 2 diabetes mellitus (T2DM), exposure to racial discrimination is adversely associated with parasympathetic, but not sympathetic, reactivity. Copyright © 2013 John Wiley & Sons, Ltd.

Gender differences in the association between perceived discrimination and adolescent smoking.

PubMed

Wiehe, Sarah E; Aalsma, Matthew C; Liu, Gilbert C; Fortenberry, J Dennis

2010-03-01

We examined associations between perceived racial/ethnic discrimination, gender, and cigarette smoking among adolescents. We examined data on Black and Latino adolescents aged 12 to 19 years who participated in the Moving to Opportunity study (N = 2561). Perceived discrimination was assessed using survey items asking about unfair treatment because of race/ethnicity in the prior 6 months. We used logistic regression to investigate associations between discrimination and smoking, stratified by gender and controlling for covariates. One fourth of adolescents reported that discrimination had occurred in at least 1 location. Discrimination was associated with increased odds of smoking among boys (odds ratio [OR] = 1.9; 95% confidence interval [CI] = 1.2, 3.0) and decreased odds among girls (OR = 0.6; 95% CI = 0.3, 1.1). Discrimination at school or work contributed to associations for girls (OR = 0.3; 95% CI = 0.1, 0.9), and discrimination at shops (OR = 2.0; 95% CI = 1.1, 3.8) and by police (OR = 2.0; 95% CI = 1.2, 3.4) contributed to associations for boys. Associations between discrimination and smoking differ by gender. Girls' decreased smoking in higher-discrimination settings may be a result of protective factors associated with where they spend time. Boys' increased smoking in higher-discrimination settings may reflect increased stress from gender-specific targeting by police and businesses.

Discrimination of edible oils and fats by combination of multivariate pattern recognition and FT-IR spectroscopy: a comparative study between different modeling methods.

PubMed

Javidnia, Katayoun; Parish, Maryam; Karimi, Sadegh; Hemmateenejad, Bahram

2013-03-01

By using FT-IR spectroscopy, many researchers from different disciplines enrich the experimental complexity of their research for obtaining more precise information. Moreover chemometrics techniques have boosted the use of IR instruments. In the present study we aimed to emphasize on the power of FT-IR spectroscopy for discrimination between different oil samples (especially fat from vegetable oils). Also our data were used to compare the performance of different classification methods. FT-IR transmittance spectra of oil samples (Corn, Colona, Sunflower, Soya, Olive, and Butter) were measured in the wave-number interval of 450-4000 cm(-1). Classification analysis was performed utilizing PLS-DA, interval PLS-DA, extended canonical variate analysis (ECVA) and interval ECVA methods. The effect of data preprocessing by extended multiplicative signal correction was investigated. Whilst all employed method could distinguish butter from vegetable oils, iECVA resulted in the best performances for calibration and external test set with 100% sensitivity and specificity. Copyright © 2012 Elsevier B.V. All rights reserved.

Discrimination between sequential and simultaneous virtual channels with electrical hearing

PubMed Central

Landsberger, David; Galvin, John J.

2011-01-01

In cochlear implants (CIs), simultaneous or sequential stimulation of adjacent electrodes can produce intermediate pitch percepts between those of the component electrodes. However, it is unclear whether simultaneous and sequential virtual channels (VCs) can be discriminated. In this study, CI users were asked to discriminate simultaneous and sequential VCs; discrimination was measured for monopolar (MP) and bipolar + 1 stimulation (BP + 1), i.e., relatively broad and focused stimulation modes. For sequential VCs, the interpulse interval (IPI) varied between 0.0 and 1.8 ms. All stimuli were presented at comfortably loud, loudness-balanced levels at a 250 pulse per second per electrode (ppse) stimulation rate. On average, CI subjects were able to reliably discriminate between sequential and simultaneous VCs. While there was no significant effect of IPI or stimulation mode on VC discrimination, some subjects exhibited better VC discrimination with BP + 1 stimulation. Subjects’ discrimination between sequential and simultaneous VCs was correlated with electrode discrimination, suggesting that spatial selectivity may influence perception of sequential VCs. To maintain equal loudness, sequential VC amplitudes were nearly double those of simultaneous VCs, presumably resulting in a broader spread of excitation. These results suggest that perceptual differences between simultaneous and sequential VCs might be explained by differences in the spread of excitation. PMID:21895094

Discrimination between sequential and simultaneous virtual channels with electrical hearing.

PubMed

Landsberger, David; Galvin, John J

2011-09-01

In cochlear implants (CIs), simultaneous or sequential stimulation of adjacent electrodes can produce intermediate pitch percepts between those of the component electrodes. However, it is unclear whether simultaneous and sequential virtual channels (VCs) can be discriminated. In this study, CI users were asked to discriminate simultaneous and sequential VCs; discrimination was measured for monopolar (MP) and bipolar + 1 stimulation (BP + 1), i.e., relatively broad and focused stimulation modes. For sequential VCs, the interpulse interval (IPI) varied between 0.0 and 1.8 ms. All stimuli were presented at comfortably loud, loudness-balanced levels at a 250 pulse per second per electrode (ppse) stimulation rate. On average, CI subjects were able to reliably discriminate between sequential and simultaneous VCs. While there was no significant effect of IPI or stimulation mode on VC discrimination, some subjects exhibited better VC discrimination with BP + 1 stimulation. Subjects' discrimination between sequential and simultaneous VCs was correlated with electrode discrimination, suggesting that spatial selectivity may influence perception of sequential VCs. To maintain equal loudness, sequential VC amplitudes were nearly double those of simultaneous VCs, presumably resulting in a broader spread of excitation. These results suggest that perceptual differences between simultaneous and sequential VCs might be explained by differences in the spread of excitation. © 2011 Acoustical Society of America

Cumulative Effect of Racial Discrimination on the Mental Health of Ethnic Minorities in the United Kingdom.

PubMed

Wallace, Stephanie; Nazroo, James; Bécares, Laia

2016-07-01

To examine the longitudinal association between cumulative exposure to racial discrimination and changes in the mental health of ethnic minority people. We used data from 4 waves (2009-2013) of the UK Household Longitudinal Study, a longitudinal household panel survey of approximately 40 000 households, including an ethnic minority boost sample of approximately 4000 households. Ethnic minority people who reported exposure to racial discrimination at 1 time point had 12-Item Short Form Health Survey (SF-12) mental component scores 1.93 (95% confidence interval [CI] = -3.31, -0.56) points lower than did those who reported no exposure to racial discrimination, whereas those who had been exposed to 2 or more domains of racial discrimination, at 2 different time points, had SF-12 mental component scores 8.26 (95% CI = -13.33, -3.18) points lower than did those who reported no experiences of racial discrimination. Controlling for racial discrimination and other socioeconomic factors reduced ethnic inequalities in mental health. Cumulative exposure to racial discrimination has incremental negative long-term effects on the mental health of ethnic minority people in the United Kingdom. Studies that examine exposure to racial discrimination at 1 point in time may underestimate the contribution of racism to poor health.

Object-based attention modulates the discrimination of level increments in stop-consonant noise bursts

PubMed Central

2018-01-01

This study tested the hypothesis that object-based attention modulates the discrimination of level increments in stop-consonant noise bursts. With consonant-vowel-consonant (CvC) words consisting of an ≈80-dB vowel (v), a pre-vocalic (Cv) and a post-vocalic (vC) stop-consonant noise burst (≈60-dB SPL), we measured discrimination thresholds (LDTs) for level increments (ΔL) in the noise bursts presented either in CvC context or in isolation. In the 2-interval 2-alternative forced-choice task, each observation interval presented a CvC word (e.g., /pæk/ /pæk/), and normal-hearing participants had to discern ΔL in the Cv or vC burst. Based on the linguistic word labels, the auditory events of each trial were perceived as two auditory objects (Cv-v-vC and Cv-v-vC) that group together the bursts and vowels, hindering selective attention to ΔL. To discern ΔL in Cv or vC, the events must be reorganized into three auditory objects: the to-be-attended pre-vocalic (Cv–Cv) or post-vocalic burst pair (vC–vC), and the to-be-ignored vowel pair (v–v). Our results suggest that instead of being automatic this reorganization requires training, in spite of using familiar CvC words. Relative to bursts in isolation, bursts in context always produced inferior ΔL discrimination accuracy (a context effect), which depended strongly on the acoustic separation between the bursts and the vowel, being much keener for the object apart from (post-vocalic) than for the object adjoining (pre-vocalic) the vowel (a temporal-position effect). Variability in CvC dimensions that did not alter the noise-burst perceptual grouping had minor effects on discrimination accuracy. In addition to being robust and persistent, these effects are relatively general, evincing in forced-choice tasks with one or two observation intervals, with or without variability in the temporal position of ΔL, and with either fixed or roving CvC standards. The results lend support to the hypothesis. PMID:29364931

Modulation of Auditory Cortex Response to Pitch Variation Following Training with Microtonal Melodies

PubMed Central

Zatorre, Robert J.; Delhommeau, Karine; Zarate, Jean Mary

2012-01-01

We tested changes in cortical functional response to auditory patterns in a configural learning paradigm. We trained 10 human listeners to discriminate micromelodies (consisting of smaller pitch intervals than normally used in Western music) and measured covariation in blood oxygenation signal to increasing pitch interval size in order to dissociate global changes in activity from those specifically associated with the stimulus feature that was trained. A psychophysical staircase procedure with feedback was used for training over a 2-week period. Behavioral tests of discrimination ability performed before and after training showed significant learning on the trained stimuli, and generalization to other frequencies and tasks; no learning occurred in an untrained control group. Before training the functional MRI data showed the expected systematic increase in activity in auditory cortices as a function of increasing micromelody pitch interval size. This function became shallower after training, with the maximal change observed in the right posterior auditory cortex. Global decreases in activity in auditory regions, along with global increases in frontal cortices also occurred after training. Individual variation in learning rate was related to the hemodynamic slope to pitch interval size, such that those who had a higher sensitivity to pitch interval variation prior to learning achieved the fastest learning. We conclude that configural auditory learning entails modulation in the response of auditory cortex to the trained stimulus feature. Reduction in blood oxygenation response to increasing pitch interval size suggests that fewer computational resources, and hence lower neural recruitment, is associated with learning, in accord with models of auditory cortex function, and with data from other modalities. PMID:23227019

Effects of environmental and pharmacological manipulations on a novel delayed nonmatching-to-sample 'working memory' procedure in unrestrained rhesus monkeys.

PubMed

Hutsell, Blake A; Banks, Matthew L

2015-08-15

Working memory is a domain of 'executive function.' Delayed nonmatching-to-sample (DNMTS) procedures are commonly used to examine working memory in both human laboratory and preclinical studies. The aim was to develop an automated DNMTS procedure maintained by food pellets in rhesus monkeys using a touch-sensitive screen attached to the housing chamber. Specifically, the DNMTS procedure was a 2-stimulus, 2-choice recognition memory task employing unidimensional discriminative stimuli and randomized delay interval presentations. DNMTS maintained a delay-dependent decrease in discriminability that was independent of the retention interval distribution. Eliminating reinforcer availability during a single delay session or providing food pellets before the session did not systematically alter accuracy, but did reduce total choices. Increasing the intertrial interval enhanced accuracy at short delays. Acute Δ(9)-THC pretreatment produced delay interval-dependent changes in the forgetting function at doses that did not alter total choices. Acute methylphenidate pretreatment only decreased total choices. All monkeys were trained to perform NMTS at the 1s training delay within 60 days of initiating operant touch training. Furthermore, forgetting functions were reliably delay interval-dependent and stable over the experimental period (∼6 months). Consistent with previous studies, increasing the intertrial interval improved DNMTS performance, whereas Δ(9)-THC disrupted DNMTS performance independent of changes in total choices. Overall, the touchscreen-based DNMTS procedure described provides an efficient method for training and testing experimental manipulations on working memory in unrestrained rhesus monkeys. Copyright © 2015 Elsevier B.V. All rights reserved.

Prior experiences of racial discrimination and racial differences in health care system distrust.

PubMed

Armstrong, Katrina; Putt, Mary; Halbert, Chanita H; Grande, David; Schwartz, Jerome Sanford; Liao, Kaijun; Marcus, Noora; Demeter, Mirar B; Shea, Judy A

2013-02-01

Factors contributing to racial differences in health care system distrust (HCSD) are currently unknown. Proposed potential contributing factors are prior experiences of racial discrimination and racial residential segregation. Random digit dialing survey of 762 African American and 1267 white adults living in 40 US metropolitan statistical areas. Measures included the Revised Health Care System Distrust scale, the Experiences of Discrimination scale, metrics of access to care, sociodemographic characteristics, and the level of racial residential segregation in the city (using the isolation index). In unadjusted analyses, African Americans had higher levels of HCSD, particularly values distrust, and greater experiences of discrimination. Experience of discrimination was also strongly associated with HCSD. Adjusting for sociodemographic characteristics, health care access, and residential segregation had little effect on the association between African American race and overall HCSD or values distrust. In contrast, adjusting for experiences of racial discrimination reversed the association so that distrust was lower among African Americans than whites (odds ratio 0.53; 95% confidence interval, 0.33-0.85 for the overall measure). The Sobel test for mediation was strongly significant (P<0.001). Higher HCSD among African Americans is explained by a greater burden of experiences of racial discrimination than whites. Reasons for higher distrust among whites after adjusting for experiences of racial discrimination are not known. Efforts to eliminate racial discrimination and restore trust given prior discrimination are needed.

Perceptual learning in temporal discrimination: asymmetric cross-modal transfer from audition to vision.

PubMed

Bratzke, Daniel; Seifried, Tanja; Ulrich, Rolf

2012-08-01

This study assessed possible cross-modal transfer effects of training in a temporal discrimination task from vision to audition as well as from audition to vision. We employed a pretest-training-post-test design including a control group that performed only the pretest and the post-test. Trained participants showed better discrimination performance with their trained interval than the control group. This training effect transferred to the other modality only for those participants who had been trained with auditory stimuli. The present study thus demonstrates for the first time that training on temporal discrimination within the auditory modality can transfer to the visual modality but not vice versa. This finding represents a novel illustration of auditory dominance in temporal processing and is consistent with the notion that time is primarily encoded in the auditory system.

Multiresolution Wavelet Analysis of Heartbeat Intervals Discriminates Healthy Patients from Those with Cardiac Pathology

NASA Astrophysics Data System (ADS)

Thurner, Stefan; Feurstein, Markus C.; Teich, Malvin C.

1998-02-01

We applied multiresolution wavelet analysis to the sequence of times between human heartbeats ( R-R intervals) and have found a scale window, between 16 and 32 heartbeat intervals, over which the widths of the R-R wavelet coefficients fall into disjoint sets for normal and heart-failure patients. This has enabled us to correctly classify every patient in a standard data set as belonging either to the heart-failure or normal group with 100% accuracy, thereby providing a clinically significant measure of the presence of heart failure from the R-R intervals alone. Comparison is made with previous approaches, which have provided only statistically significant measures.

Lifetime Discrimination Associated with Greater Likelihood of Premenstrual Dysphoric Disorder

PubMed Central

Desai, Rani; Kasl, Stanislav; Levy, Becca R.

2011-01-01

Abstract Objectives To evaluate whether the stressor of perceived discrimination was associated with premenstrual dysphoric disorder (PMDD) and premenstrual symptoms among minority women. This study builds on previous research that found perceived discrimination was positively associated with other psychiatric illnesses. Methods Participants were 2718 Asian, Latina, and black premenopausal women aged 18–40 years who completed the World Mental Health Composite International Diagnostic Interview for the National Latino and Asian American Survey or the National Survey of American Life. Perceived discrimination was assessed with the Everyday Discrimination Scale. DSM-IV-based diagnostic algorithms generated a provisional lifetime diagnosis of PMDD. Results Eighty-three percent of the participants reported experiencing discrimination (due to race, gender, age, height or weight, or other reasons) in their lifetimes. The frequency of perceived discrimination was positively associated with PMDD (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.05-1.10) and premenstrual symptoms (OR 1.04, 95% CI 1.02-1.05), independent of demographic covariates and social desirability. Women reporting gender discrimination (OR 5.18, 95% CI 1.80-14.90), race discrimination (OR 4.14, 95% CI 1.54-11.11), and other forms of discrimination (OR 6.43, 95% CI 2.11-19.65) were significantly more likely than women without experiences of discrimination to have PMDD. Subtle discrimination was more strongly associated with PMDD (OR 1.12, 95% CI 1.01-1.23) than was blatant discrimination (OR 1.04, 95% CI 0.94-1.15). Conclusions This study is the first to demonstrate that perceived discrimination is associated with PMDD and premenstrual symptoms. These findings suggest that the prevalence of these conditions may be lessened by reducing discrimination in women's lives. PMID:21671777

Lifetime discrimination associated with greater likelihood of premenstrual dysphoric disorder.

PubMed

Pilver, Corey E; Desai, Rani; Kasl, Stanislav; Levy, Becca R

2011-06-01

To evaluate whether the stressor of perceived discrimination was associated with premenstrual dysphoric disorder (PMDD) and premenstrual symptoms among minority women. This study builds on previous research that found perceived discrimination was positively associated with other psychiatric illnesses. Participants were 2718 Asian, Latina, and black premenopausal women aged 18-40 years who completed the World Mental Health Composite International Diagnostic Interview for the National Latino and Asian American Survey or the National Survey of American Life. Perceived discrimination was assessed with the Everyday Discrimination Scale. DSM-IV-based diagnostic algorithms generated a provisional lifetime diagnosis of PMDD. Eighty-three percent of the participants reported experiencing discrimination (due to race, gender, age, height or weight, or other reasons) in their lifetimes. The frequency of perceived discrimination was positively associated with PMDD (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.05-1.10) and premenstrual symptoms (OR 1.04, 95% CI 1.02-1.05), independent of demographic covariates and social desirability. Women reporting gender discrimination (OR 5.18, 95% CI 1.80-14.90), race discrimination (OR 4.14, 95% CI 1.54-11.11), and other forms of discrimination (OR 6.43, 95% CI 2.11-19.65) were significantly more likely than women without experiences of discrimination to have PMDD. Subtle discrimination was more strongly associated with PMDD (OR 1.12, 95% CI 1.01-1.23) than was blatant discrimination (OR 1.04, 95% CI 0.94-1.15). This study is the first to demonstrate that perceived discrimination is associated with PMDD and premenstrual symptoms. These findings suggest that the prevalence of these conditions may be lessened by reducing discrimination in women's lives.

Longitudinal Reciprocal Relationships between Discrimination and Ethnic Affect or Depressive Symptoms among Chinese American Adolescents

PubMed Central

Hou, Yang; Kim, Su Yeong; Wang, Yijie; Shen, Yishan; Orozco-Lapray, Diana

2015-01-01

Discrimination plays an important role in the development of ethnic minority adolescents. However, previous studies have often adopted a unidirectional model examining the influence of discrimination on adolescent development, thus leaving the potential reciprocal relationship between them understudied. Moreover, there is a dearth of studies on Chinese Americans in the discrimination literature. Therefore, this study aimed to examine the reciprocal relationships between discrimination and two measures of adolescent outcomes (i.e., ethnic affect and depressive symptoms) from early adolescence to emerging adulthood in Chinese Americans. Participants were 444 adolescents (54% female), followed at four-year intervals, beginning at 7th or 8th grade (Mage.wave1 = 13.03) in 2002, for a total of three waves. An examination of cross-lagged autoregressive models revealed two major findings. First, in contrast to the rejection–identification model, perceived discrimination at early adolescence negatively related to ethnic affect at middle adolescence. Conversely, ethnic affect at early adolescence also negatively related to discrimination at middle adolescence. These results held the same direction but became insignificant from middle adolescence to emerging adulthood. Second, perceived discrimination positively related to depressive symptoms across the studied developmental periods, and depressive symptoms positively related to perceived discrimination from middle adolescence to emerging adulthood. The strength of these longitudinal relationships did not change significantly across developmental periods or gender. These findings highlight the bidirectional relationship between perceived discrimination and adolescent outcomes; they also demonstrate the value of studying the discrimination experiences of Chinese Americans. PMID:25963446

Associations between sickness absence and harassment, threats, violence, or discrimination: a cross-sectional study of the Swedish Police.

PubMed

Svedberg, Pia; Alexanderson, Kristina

2012-01-01

To study if sick leave among employees in the Swedish Police was associated with experiences of discrimination, harassment, or (threats of) violence. All employees in the Swedish Police in 2005. Analyses of data from a questionnaire to all employees; 74% (n=16,725) responded. Odds ratios (OR) with 95% confidence intervals (CI) between sick leave and the studied factors were assessed. The rate of sickness absence was higher for women (12%) than for men (8%) (p< 0.001). More women than men had experienced discrimination, while more men reported harassment from the public and experiences of threats or violence. ORs were significant between sick-leave and discrimination, sexual harassment, and violence, and higher for the men. Associations between harassment from the public, threats of violence or violence, and sickness absence were statistically significant for men only. The study identifies the importance of investigating discrimination, harassment, and violence in relation to health outcomes for both male and female Police employees.

Morning and Evening Home Blood Pressure and Risks of Incident Stroke and Coronary Artery Disease in the Japanese General Practice Population: The Japan Morning Surge-Home Blood Pressure Study.

PubMed

Hoshide, Satoshi; Yano, Yuichiro; Haimoto, Hajime; Yamagiwa, Kayo; Uchiba, Kiyoshi; Nagasaka, Shoichiro; Matsui, Yoshio; Nakamura, Akira; Fukutomi, Motoki; Eguchi, Kazuo; Ishikawa, Joji; Kario, Kazuomi

2016-07-01

Our aim is to determine the optimal time schedule for home blood pressure (BP) monitoring that best predicts stroke and coronary artery disease in general practice. The Japan Morning Surge-Home Blood Pressure (J-HOP) study is a nationwide practice-based study that included 4310 Japanese with a history of or risk factors for cardiovascular disease, or both (mean age, 65 years; 79% used antihypertensive medication). Home BP measures were taken twice daily (morning and evening) over 14 days at baseline. During a mean follow-up of 4 years (16 929 person-years), 74 stroke and 77 coronary artery disease events occurred. Morning systolic BP (SBP) improved the discrimination of incident stroke (C statistics, 0.802; 95% confidence interval, 0.692-0.911) beyond traditional risk factors including office SBP (0.756; 0.646-0.866), whereas the changes were smaller with evening SBP (0.764; 0.653-0.874). The addition of evening SBP to the model (including traditional risk factors plus morning SBP) significantly reduced the discrimination of incident stroke (C statistics difference, -0.008; 95% confidence interval: -0.015 to -0.008; P=0.03). The category-free net reclassification improvement (0.3606; 95% confidence interval, 0.1317-0.5896), absolute integrated discrimination improvement (0.015; SE, 0.005), and relative integrated discrimination improvement (58.3%; all P<0.01) with the addition of morning SBP to the model (including traditional risk factors) were greater than those with evening SBP and with combined morning and evening SBP. Neither morning nor evening SBP improved coronary artery disease risk prediction. Morning home SBP itself should be evaluated to ensure best stroke prediction in clinical practice, at least in Japan. This should be confirmed in the different ethnic groups. URL: http://www.umin.ac.jp/ctr/. Unique identifier: UMIN000000894. © 2016 American Heart Association, Inc.

Association of discrimination-related trauma with sexual risk among HIV-positive African American men who have sex with men.

PubMed

Fields, Errol L; Bogart, Laura M; Galvan, Frank H; Wagner, Glenn J; Klein, David J; Schuster, Mark A

2013-05-01

We investigated whether 1 form of traumatic stress, discrimination-related trauma (e.g., physical assault because of race), was associated with unprotected anal intercourse, especially when compared with non-discrimination-related trauma, among African American men who have sex with men. A convenience sample of 131 HIV-positive African American men who have sex with men receiving antiretroviral treatment completed audio computer-assisted self-interviews that covered unprotected anal intercourse, interpersonal trauma, and whether trauma was because of discrimination on the basis of race/ethnicity, HIV serostatus, or sexual orientation. Sixty percent reported at least 1 interpersonal trauma; they attributed at least 1 trauma to being gay (47%), African American (17%), or HIV positive (9%). In a multivariate regression, experiencing discrimination-related trauma was significantly associated with unprotected anal intercourse (adjusted odds ratio [AOR] = 2.4; 95% confidence interval [CI] = 1.0, 5.7; P = .04), whereas experiencing non-discrimination-related trauma was not (AOR = 1.3; 95% CI = 0.6, 3.1; P = .53). HIV-positive African American men who have sex with men experience high levels of discrimination-related trauma, a stressor associated with greater risk taking. HIV prevention interventions should consider the potential damaging effects of discrimination in the context of trauma.

Inverse associations between perceived racism and coronary artery calcification.

PubMed

Everage, Nicholas J; Gjelsvik, Annie; McGarvey, Stephen T; Linkletter, Crystal D; Loucks, Eric B

2012-03-01

To evaluate whether racial discrimination is associated with coronary artery calcification (CAC) in African-American participants of the Coronary Artery Risk Development in Young Adults (CARDIA) study. The study included American Black men (n = 571) and women (n = 791) aged 33 to 45 years in the CARDIA study. Perceived racial discrimination was assessed based on the Experiences of Discrimination scale (range, 1-35). CAC was evaluated using computed tomography. Primary analyses assessed associations between perceived racial discrimination and presence of CAC using multivariable-adjusted logistic regression analysis, adjusted for age, gender, socioeconomic position (SEP), psychosocial variables, and coronary heart disease (CHD) risk factors. In age- and gender-adjusted logistic regression models, odds of CAC decreased as the perceived racial discrimination score increased (odds ratio [OR], 0.94; 95% confidence interval [CI], 0.90-0.98 per 1-unit increase in Experiences of Discrimination scale). The relationship did not markedly change after further adjustment for SEP, psychosocial variables, or CHD risk factors (OR, 0.93; 95% CI, 0.87-0.99). Perceived racial discrimination was negatively associated with CAC in this study. Estimation of more forms of racial discrimination as well as replication of analyses in other samples will help to confirm or refute these findings. Copyright © 2012 Elsevier Inc. All rights reserved.

Evaluation of Visual Field and Imaging Outcomes for Glaucoma Clinical Trials (An American Ophthalomological Society Thesis).

PubMed

Garway-Heath, David F; Quartilho, Ana; Prah, Philip; Crabb, David P; Cheng, Qian; Zhu, Haogang

2017-08-01

To evaluate the ability of various visual field (VF) analysis methods to discriminate treatment groups in glaucoma clinical trials and establish the value of time-domain optical coherence tomography (TD OCT) imaging as an additional outcome. VFs and retinal nerve fibre layer thickness (RNFLT) measurements (acquired by TD OCT) from 373 glaucoma patients in the UK Glaucoma Treatment Study (UKGTS) at up to 11 scheduled visits over a 2 year interval formed the cohort to assess the sensitivity of progression analysis methods. Specificity was assessed in 78 glaucoma patients with up to 11 repeated VF and OCT RNFLT measurements over a 3 month interval. Growth curve models assessed the difference in VF and RNFLT rate of change between treatment groups. Incident progression was identified by 3 VF-based methods: Guided Progression Analysis (GPA), 'ANSWERS' and 'PoPLR', and one based on VFs and RNFLT: 'sANSWERS'. Sensitivity, specificity and discrimination between treatment groups were evaluated. The rate of VF change was significantly faster in the placebo, compared to active treatment, group (-0.29 vs +0.03 dB/year, P <.001); the rate of RNFLT change was not different (-1.7 vs -1.1 dB/year, P =.14). After 18 months and at 95% specificity, the sensitivity of ANSWERS and PoPLR was similar (35%); sANSWERS achieved a sensitivity of 70%. GPA, ANSWERS and PoPLR discriminated treatment groups with similar statistical significance; sANSWERS did not discriminate treatment groups. Although the VF progression-detection method including VF and RNFLT measurements is more sensitive, it does not improve discrimination between treatment arms.

Usefulness of the addition of beta-2-microglobulin, cystatin C and C-reactive protein to an established risk factors model to improve mortality risk prediction in patients undergoing coronary angiography.

PubMed

Nead, Kevin T; Zhou, Margaret J; Caceres, Roxanne Diaz; Sharp, Stephen J; Wehner, Mackenzie R; Olin, Jeffrey W; Cooke, John P; Leeper, Nicholas J

2013-03-15

Evidence-based therapies are available to reduce the risk for death from cardiovascular disease, yet many patients go untreated. Novel methods are needed to identify those at highest risk for cardiovascular death. In this study, the biomarkers β2-microglobulin, cystatin C, and C-reactive protein were measured at baseline in a cohort of participants who underwent coronary angiography. Adjusted Cox proportional-hazards models were used to determine whether the biomarkers predicted all-cause and cardiovascular mortality. Additionally, improvements in risk reclassification and discrimination were evaluated by calculating the net reclassification improvement, C-index, and integrated discrimination improvement with the addition of the biomarkers to a baseline model of risk factors for cardiovascular disease and death. During a median follow-up period of 5.6 years, there were 78 deaths among 470 participants. All biomarkers independently predicted future all-cause and cardiovascular mortality. A significant improvement in risk reclassification was observed for all-cause (net reclassification improvement 35.8%, p = 0.004) and cardiovascular (net reclassification improvement 61.9%, p = 0.008) mortality compared to the baseline risk factors model. Additionally, there was significantly increased risk discrimination with C-indexes of 0.777 (change in C-index 0.057, 95% confidence interval 0.016 to 0.097) and 0.826 (change in C-index 0.071, 95% confidence interval 0.010 to 0.133) for all-cause and cardiovascular mortality, respectively. Improvements in risk discrimination were further supported using the integrated discrimination improvement index. In conclusion, this study provides evidence that β2-microglobulin, cystatin C, and C-reactive protein predict mortality and improve risk reclassification and discrimination for a high-risk cohort of patients who undergo coronary angiography. Copyright © 2013 Elsevier Inc. All rights reserved.

Cardiovascular disease and perceived weight, racial, and gender discrimination in U.S. adults.

PubMed

Udo, Tomoko; Grilo, Carlos M

2017-09-01

To date, most research on perceived discrimination and cardiovascular disease (CVD) has examined racial discrimination although other forms of discrimination may also impact physical and mental health. The current study investigated the relationship between three forms of discrimination (weight, race, and gender) and 3-year incidence of CVD in a large national sample of U.S. adults. 26,992 adults (55.5% women) who participated in the 2001-2002 and 2004-2005 National Epidemiologic Survey of Alcohol and Related Conditions (NESARC) were included in this study. Multiple logistic regression analyses were used to calculate odds ratios (OR) and 95% confidence intervals (CI) for three forms of perceived discrimination (simultaneously included in equations after adjusting for relevant potential confounds) for predicting CVD incidence at Wave 2. Perceived weight and racial discrimination were associated with significantly greater likelihood of reporting myocardial infarction (OR=2.56 [95% CI=1.31-4.98], OR=1.84 [95% CI=1.19-2.84], respectively) and minor heart conditions (OR=1.48 [95% CI=1.11-1.98], OR=1.41 [95% CI=1.18-1.70], respectively). Perceived racial discrimination was also significantly associated with greater likelihood of reporting arteriosclerosis (OR=1.61 [95% CI=1.11-2.34]). Odds ratios for diagnoses of arteriosclerosis, myocardial infarction, and other minor heart disease were largest for individuals reporting multiple forms of discrimination. Adults who experience weight and racial discrimination, and especially multiple forms of discrimination, may be at heightened risk for CVD. Perceived discrimination may be important to consider during assessment of life stressors by health providers. Future research should address the mechanisms that link discrimination and CVD to assist public health and policy efforts to reduce discrimination. Copyright © 2017. Published by Elsevier Inc.

Formant-frequency discrimination of synthesized vowels in budgerigars (Melopsittacus undulatus) and humans.

PubMed

Henry, Kenneth S; Amburgey, Kassidy N; Abrams, Kristina S; Idrobo, Fabio; Carney, Laurel H

2017-10-01

Vowels are complex sounds with four to five spectral peaks known as formants. The frequencies of the two lowest formants, F1and F2, are sufficient for vowel discrimination. Behavioral studies show that many birds and mammals can discriminate vowels. However, few studies have quantified thresholds for formant-frequency discrimination. The present study examined formant-frequency discrimination in budgerigars (Melopsittacus undulatus) and humans using stimuli with one or two formants and a constant fundamental frequency of 200 Hz. Stimuli had spectral envelopes similar to natural speech and were presented with random level variation. Thresholds were estimated for frequency discrimination of F1, F2, and simultaneous F1 and F2 changes. The same two-down, one-up tracking procedure and single-interval, two-alternative task were used for both species. Formant-frequency discrimination thresholds were as sensitive in budgerigars as in humans and followed the same patterns across all conditions. Thresholds expressed as percent frequency difference were higher for F1 than for F2, and were unchanged between stimuli with one or two formants. Thresholds for simultaneous F1 and F2 changes indicated that discrimination was based on combined information from both formant regions. Results were consistent with previous human studies and show that budgerigars provide an exceptionally sensitive animal model of vowel feature discrimination.

Age-related change in fast adaptation mechanisms measured with the scotopic full-field ERG.

PubMed

Tillman, Megan A; Panorgias, Athanasios; Werner, John S

2016-06-01

To quantify the response dynamics of fast adaptation mechanisms of the scotopic ERG in younger and older adults using full-field m-sequence flash stimulation. Scotopic ERGs were measured for a series of flashes separated by 65 ms over a range of 260 ms in 16 younger (20-26, 22.2 ± 2.1; range mean ±1 SD) and 16 older (65-85, 71.2 ± 7) observers without retinal pathology. A short-wavelength (λ peak = 442 nm) LED was used for scotopic stimulation, and the flashes ranged from 0.0001 to 0.01 cd s m(-2). The complete binary kernel series was derived from the responses to the m-sequence flash stimulation, and the first- and second-order kernel responses were analyzed. The first-order kernel represented the response to a single, isolated flash, while the second-order kernels reflected the adapted flash responses that followed a single flash by one or more base intervals. B-wave amplitudes of the adapted flash responses were measured and plotted as a function of interstimulus interval to describe the recovery of the scotopic ERG. A linear function was fitted to the linear portion of the recovery curve, and the slope of the line was used to estimate the rate of fast adaptation recovery. The amplitudes of the isolated flash responses and rates of scotopic fast adaptation recovery were compared between the younger and older participants using a two-way ANOVA. The isolated flash responses and rates of recovery were found to be significantly lower in the older adults. However, there was no difference between the two age groups in response amplitude or recovery rate after correcting for age-related changes in the density of the ocular media. These results demonstrated that the rate of scotopic fast adaptation recovery of normal younger and older adults is similar when stimuli are equated for retinal illuminance.

Male vocal competition is dynamic and strongly affected by social contexts in music frogs.

PubMed

Fang, Guangzhan; Jiang, Fan; Yang, Ping; Cui, Jianguo; Brauth, Steven E; Tang, Yezhong

2014-03-01

Male-male vocal competition in anuran species is critical for mating success; however, it is also highly time-consuming, energetically demanding and likely to increase predation risks. Thus, we hypothesized that changes in the social context would cause male vocal competition to change in real time in order to minimize the costs and maximize the benefits of competition. To test this hypothesis, we assessed the effect of repeating playbacks of either white noise (WN) or male advertisement calls on male call production in the Emei music frog (Babina daunchina), a species in which males build mud-retuse burrows and call from within these nests. Previous studies have shown that calls produced from inside burrows are highly sexually attractive (HSA) to females while those produced outside nests are of low sexual attractiveness (LSA). Results showed that most subjects called responsively after the end of WN playbacks but before the onset of conspecific call stimuli although call numbers were similar, indicating that while males adjusted competitive patterns according to the biological significance of signals, their competitive motivation did not change. Furthermore, these data indicate that the frogs had evolved the ability of interval timing. Moreover, when the inter-stimulus interval (ISI) between playbacks was varied, the subjects preferentially competed with HSA calls when the ISI was short (<4 s) but responded equally to HSA and LSA calls if the ISI was long (≥4 s), suggesting that males allocate competitive efforts depending on both the perceived sexual attractiveness of rivals and the time available for calling. Notably, approximately two-thirds of male calls occurred in response to HSA calls, a preference rate comparable to that previously found for females in phonotaxis experiments and consistent with the idea that the mechanisms underlying both the male's competitive responses to rivals and the female's preferences toward potential mates coevolved under the same selective pressure.

Intracortical inhibition in the human trigeminal motor system.

PubMed

Jaberzadeh, Shapour; Pearce, Sophie L; Miles, Timothy S; Türker, Kemal S; Nordstrom, Michael A

2007-08-01

To investigate the presence and features of short-interval intracortical inhibition (SICI) in the human trigeminal motor system. Surface electromyogram (EMG) was recorded from left and right digastric muscles in 7 subjects, along with additional experiments with intramuscular EMG in 2 subjects. Focal transcranial magnetic stimulation (TMS) was used to activate the motor cortex of one hemisphere and elicit motor evoked potentials (MEPs) in digastric muscles on each side, at rest and while subjects activated the muscles at 10% maximal EMG. Paired or single TMS pulses were delivered in blocks of trials, while conditioning TMS intensity and interstimulus interval (ISI) were varied. At rest, paired TMS (3-ms ISI) with conditioning intensities 0.8-0.9x active motor threshold (TA) reduced the digastric MEP amplitude to a similar extent bilaterally. Conditioning at 0.5-0.7TA did not significantly reduce the MEP. MEP amplitude was reduced to a similar extent in both digastric muscles by ISIs between 1 and 4 ms (0.8TA). Voluntary bilateral activation of digastric muscles reduced the effectiveness of conditioning TMS compared to the resting state, with no differences between sides. The similarity of the responses in both digastric muscles was not due to EMG cross-talk (estimated to be approximately 10% in surface records and approximately 2% in intramuscular records), as the intramuscular records showed the same pattern as the surface records. The effects of paired-pulse TMS on digastric are similar to those reported for contralateral hand muscles, and are consistent with activation of SICI circuits in M1 by conditioning TMS. Our evidence further suggests that the corticomotor representations of left and right digastric muscles in M1 of a single hemisphere receive analogous inhibitory modulation from SICI circuits. SICI has been demonstrated in the face area of motor cortex controlling the trigeminal motor system in normal subjects. This method can be used to investigate abnormalities of SICI in movement disorders affecting the masticatory muscles in humans.

Cortical activity patterns predict robust speech discrimination ability in noise

PubMed Central

Shetake, Jai A.; Wolf, Jordan T.; Cheung, Ryan J.; Engineer, Crystal T.; Ram, Satyananda K.; Kilgard, Michael P.

2012-01-01

The neural mechanisms that support speech discrimination in noisy conditions are poorly understood. In quiet conditions, spike timing information appears to be used in the discrimination of speech sounds. In this study, we evaluated the hypothesis that spike timing is also used to distinguish between speech sounds in noisy conditions that significantly degrade neural responses to speech sounds. We tested speech sound discrimination in rats and recorded primary auditory cortex (A1) responses to speech sounds in background noise of different intensities and spectral compositions. Our behavioral results indicate that rats, like humans, are able to accurately discriminate consonant sounds even in the presence of background noise that is as loud as the speech signal. Our neural recordings confirm that speech sounds evoke degraded but detectable responses in noise. Finally, we developed a novel neural classifier that mimics behavioral discrimination. The classifier discriminates between speech sounds by comparing the A1 spatiotemporal activity patterns evoked on single trials with the average spatiotemporal patterns evoked by known sounds. Unlike classifiers in most previous studies, this classifier is not provided with the stimulus onset time. Neural activity analyzed with the use of relative spike timing was well correlated with behavioral speech discrimination in quiet and in noise. Spike timing information integrated over longer intervals was required to accurately predict rat behavioral speech discrimination in noisy conditions. The similarity of neural and behavioral discrimination of speech in noise suggests that humans and rats may employ similar brain mechanisms to solve this problem. PMID:22098331

Proceedings of the Fourth Precise Time and Time Interval Planning Meeting

NASA Technical Reports Server (NTRS)

Acrivos, H. N. (Compiler); Wardrip, S. C. (Compiler)

1972-01-01

The proceedings of a conference on Precise Time and Time Interval Planning are presented. The subjects discussed include the following: (1) satellite timing techniques, precision frequency sources, and very long baseline interferometry, (2) frequency stabilities and communications, and (3) very low frequency and ultrahigh frequency propagation and use. Emphasis is placed on the accuracy of time discrimination obtained with time measuring equipment and specific applications of time measurement to military operations and civilian research projects.

Nondepressive Psychosocial Factors and CKD Outcomes in Black Americans.

PubMed

Lunyera, Joseph; Davenport, Clemontina A; Bhavsar, Nrupen A; Sims, Mario; Scialla, Julia; Pendergast, Jane; Hall, Rasheeda; Tyson, Crystal C; Russell, Jennifer St Clair; Wang, Wei; Correa, Adolfo; Boulware, L Ebony; Diamantidis, Clarissa J

2018-02-07

Established risk factors for CKD do not fully account for risk of CKD in black Americans. We studied the association of nondepressive psychosocial factors with risk of CKD in the Jackson Heart Study. We used principal component analysis to identify underlying constructs from 12 psychosocial baseline variables (perceived daily, lifetime, and burden of lifetime discrimination; stress; anger in; anger out; hostility; pessimism; John Henryism; spirituality; perceived social status; and social support). Using multivariable models adjusted for demographics and comorbidity, we examined the association of psychosocial variables with baseline CKD prevalence, eGFR decline, and incident CKD during follow-up. Of 3390 (64%) Jackson Heart Study participants with the required data, 656 (19%) had prevalent CKD. Those with CKD (versus no CKD) had lower perceived daily (mean [SD] score =7.6 [8.5] versus 9.7 [9.0]) and lifetime discrimination (2.5 [2.0] versus 3.1 [2.2]), lower perceived stress (4.2 [4.0] versus 5.2 [4.4]), higher hostility (12.1 [5.2] versus 11.5 [4.8]), higher John Henryism (30.0 [4.8] versus 29.7 [4.4]), and higher pessimism (2.3 [2.2] versus 2.0 [2.1]; all P <0.05). Principal component analysis identified three factors from the 12 psychosocial variables: factor 1, life stressors (perceived discrimination, stress); factor 2, moods (anger, hostility); and, factor 3, coping strategies (John Henryism, spirituality, social status, social support). After adjustments, factor 1 (life stressors) was negatively associated with prevalent CKD at baseline among women only: odds ratio, 0.76 (95% confidence interval, 0.65 to 0.89). After a median follow-up of 8 years, identified psychosocial factors were not significantly associated with eGFR decline (life stressors: β =0.08; 95% confidence interval, -0.02 to 0.17; moods: β =0.03; 95% confidence interval, -0.06 to 0.13; coping: β =-0.02; 95% confidence interval, -0.12 to 0.08) or incident CKD (life stressors: odds ratio, 1.07; 95% confidence interval, 0.88 to 1.29; moods: odds ratio, 1.02; 95% confidence interval, 0.84 to 1.24; coping: odds ratio, 0.91; 95% confidence interval, 0.75 to 1.11). Greater life stressors were associated with lower prevalence of CKD at baseline in the Jackson Heart Study. However, psychosocial factors were not associated with risk of CKD over a median follow-up of 8 years. This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_01_03_CJASNPodcast_18_2_L.mp3. Copyright © 2018 by the American Society of Nephrology.

Age effects on discrimination of timing in auditory sequences

NASA Astrophysics Data System (ADS)

Fitzgibbons, Peter J.; Gordon-Salant, Sandra

2004-08-01

The experiments examined age-related changes in temporal sensitivity to increments in the interonset intervals (IOI) of components in tonal sequences. Discrimination was examined using reference sequences consisting of five 50-ms tones separated by silent intervals; tone frequencies were either fixed at 4 kHz or varied within a 2-4-kHz range to produce spectrally complex patterns. The tonal IOIs within the reference sequences were either equal (200 or 600 ms) or varied individually with an average value of 200 or 600 ms to produce temporally complex patterns. The difference limen (DL) for increments of IOI was measured. Comparison sequences featured either equal increments in all tonal IOIs or increments in a single target IOI, with the sequential location of the target changing randomly across trials. Four groups of younger and older adults with and without sensorineural hearing loss participated. Results indicated that DLs for uniform changes of sequence rate were smaller than DLs for single target intervals, with the largest DLs observed for single targets embedded within temporally complex sequences. Older listeners performed more poorly than younger listeners in all conditions, but the largest age-related differences were observed for temporally complex stimulus conditions. No systematic effects of hearing loss were observed.

Social discrimination, stress, and risk of unintended pregnancy among young women.

PubMed

Hall, Kelli Stidham; Kusunoki, Yasamin; Gatny, Heather; Barber, Jennifer

2015-03-01

Prior research linking young women's mental health to family planning outcomes has often failed to consider their social circumstances and the intersecting biosocial mechanisms that shape stress and depression as well as reproductive outcomes during adolescence and young adulthood. We extend our previous work to investigate relationships between social discrimination, stress and depression symptoms, and unintended pregnancy among adolescent and young adult women. Data were drawn from 794 women aged 18-20 years in a longitudinal cohort study. Baseline and weekly surveys assessed psychosocial information including discrimination (Everyday Discrimination Scale), stress (Perceived Stress Scale), depression (Center for Epidemiologic Studies-Depression Scale), and reproductive outcomes. Multilevel, mixed-effects logistic regression and discrete-time hazard models estimated associations between discrimination, mental health, and pregnancy. Baron and Kenny's method was used to test mediation effects of stress and depression on discrimination and pregnancy. The mean discrimination score was 19/45 points; 20% reported moderate/high discrimination. Discrimination scores were higher among women with stress and depression symptoms versus those without symptoms (21 vs. 18 points for both, p < .001). Pregnancy rates (14% overall) were higher among women with moderate/high (23%) versus low (11%) discrimination (p < .001). Discrimination was associated with stress (adjusted relative risk ratio, [aRR], 2.2; 95% confidence interval [CI], 1.4-3.4), depression (aRR, 2.4; CI, 1.5-3.7), and subsequent pregnancy (aRR, 1.8; CI, 1.1-3.0). Stress and depression symptoms did not mediate discrimination's effect on pregnancy. Discrimination was associated with an increased risk of mental health symptoms and unintended pregnancy among these young women. The interactive social and biological influences on reproductive outcomes during adolescence and young adulthood warrant further study. Copyright © 2015 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Visual discrimination of local surface structure: slant, tilt, and curvedness.

PubMed

Norman, J Farley; Todd, James T; Norman, Hideko F; Clayton, Anna Marie; McBride, T Ryan

2006-03-01

In four experiments, observers were required to discriminate interval or ordinal differences in slant, tilt, or curvedness between designated probe points on randomly shaped curved surfaces defined by shading, texture, and binocular disparity. The results reveal that discrimination thresholds for judgments of slant or tilt typically range between 4 degrees and 10 degrees; that judgments of one component are unaffected by simultaneous variations in the other; and that the individual thresholds for either the slant or tilt components of orientation are approximately equal to those obtained for judgments of the total orientation difference between two probed regions. Performance was much worse, however, for judgments of curvedness, and these judgments were significantly impaired when there were simultaneous variations in the shape index parameter of curvature.

Longitudinal Reciprocal Relationships Between Discrimination and Ethnic Affect or Depressive Symptoms Among Chinese American Adolescents.

PubMed

Hou, Yang; Kim, Su Yeong; Wang, Yijie; Shen, Yishan; Orozco-Lapray, Diana

2015-11-01

Discrimination plays an important role in the development of ethnic minority adolescents. However, previous studies have often adopted a unidirectional model examining the influence of discrimination on adolescent development, thus leaving the potential reciprocal relationship between them understudied. Moreover, there is a dearth of studies on Chinese Americans in the discrimination literature. Therefore, this study aimed to examine the reciprocal relationships between discrimination and two measures of adolescent outcomes (i.e., ethnic affect and depressive symptoms) from early adolescence to emerging adulthood in Chinese Americans. Participants were 444 adolescents (54 % female), followed at four-year intervals, beginning at 7th or 8th grade (M age.wave1 = 13.03) in 2002, for a total of three waves. An examination of cross-lagged autoregressive models revealed two major findings. First, in contrast to the rejection-identification model, perceived discrimination at early adolescence negatively related to ethnic affect at middle adolescence. Conversely, ethnic affect at early adolescence also negatively related to discrimination at middle adolescence. These results held the same direction but became insignificant from middle adolescence to emerging adulthood. Second, perceived discrimination positively related to depressive symptoms across the studied developmental periods, and depressive symptoms positively related to perceived discrimination from middle adolescence to emerging adulthood. The strength of these longitudinal relationships did not change significantly across developmental periods or gender. These findings highlight the bidirectional relationship between perceived discrimination and adolescent outcomes; they also demonstrate the value of studying the discrimination experiences of Chinese Americans.

Differential effect of race, education, gender, and language discrimination on glycemic control in adults with type 2 diabetes.

PubMed

Reynolds, D Brice; Walker, Rebekah J; Campbell, Jennifer A; Egede, Leonard E

2015-04-01

Discrimination has been linked to negative health outcomes, but little research has investigated different types of discrimination to determine if some have a greater impact on outcomes. We examined the differential effect of discrimination based on race, level of education, gender, and language on glycemic control in adults with type 2 diabetes. Six hundred two patients with type 2 diabetes from two adult primary care clinics in the southeastern United States completed validated questionnaires. Questions included perceived discrimination because of race/ethnicity, level of education, sex/gender, or language. A multiple linear regression model assessed the differential effect of each type of perceived discrimination on glycemic control while adjusting for relevant covariates, including race, site, gender, marital status, duration of diabetes, number of years in school, number of hours worked per week, income, and health status. The mean age was 61.5 years, and the mean duration of diabetes was 12.3 years. Of the sample, 61.6% were men, and 64.9% were non-Hispanic black. In adjusted models, education discrimination remained significantly associated with glycemic control (β=0.47; 95% confidence interval, 0.03, 0.92). Race, gender and language discrimination were not significantly associated with poor glycemic control in either unadjusted or adjusted analyses. Discrimination based on education was found to be significantly associated with poor glycemic control. The findings suggest that education discrimination may be an important social determinant to consider when providing care to patients with type 2 diabetes and should be assessed separate from other types of discrimination, such as that based on race.

Moderators of the association between discrimination and alcohol consumption: findings from a representative sample of Brazilian university students.

PubMed

Coelho, Isabela Zeni; Bastos, João Luiz; Celeste, Roger Keller

2015-01-01

Few studies about discrimination and patterns of alcohol consumption among youth populations have been conducted outside the United States addressing different types of discriminatory experiences, in addition to racially motivated events. This study investigated moderators of the association between discrimination attributed to single and multiple reasons and patterns of alcohol consumption. This cross-sectional study enrolled a representative sample (n = 1,264) of undergraduate students from Florianópolis, southern Brazil, in 2013. Analyses included adjustment of associations for covariates in ordinal logistic regression models and the examination of effect modification by common mental disorders, year of study and age. Discrimination was reported by 65.8% of the students, and alcohol consumption, by 80.0%. Over half of the students reported being discriminated against for two or more reasons. The odds of alcohol-related problems were higher among lastyear students that reported discrimination (odds ratio [OR] = 1.9, 95% confidence interval [95%CI] 1.0-3.4) or multiple reasons for being discriminated against (OR = 2.3, 95%CI 1.3- 4.3), when compared to first-year students that did not report discrimination. For the whole sample, there were no associations between discrimination, discrimination attributed to multiple reasons and patterns of alcohol consumption (OR = 1.0, 95%CI 0.8-1.4; and OR = 0.9, 95%CI 0.5-1.6). The effects of discrimination on the patterns of alcohol consumption are seen at a critical period in university life, specifically during the completion of undergraduate studies.

Darker Skin Tone Increases Perceived Discrimination among Male but Not Female Caribbean Black Youth.

PubMed

Assari, Shervin; Caldwell, Cleopatra Howard

2017-12-12

Among most minority groups, males seem to report higher levels of exposure and vulnerability to racial discrimination. Although darker skin tone may increase exposure to racial discrimination, it is yet unknown whether skin tone similarly influences perceived discrimination among male and female Caribbean Black youth. The current cross-sectional study tests the role of gender on the effects of skin tone on perceived discrimination among Caribbean Black youth. Data came from the National Survey of American Life-Adolescent Supplement (NSAL-A), 2003-2004, which included 360 Caribbean Black youth (ages 13 to 17). Demographic factors (age and gender), socioeconomic status (SES; family income, income to needs ratio, and subjective SES), skin tone, and perceived everyday discrimination were measured. Linear regressions were used for data analysis. In the pooled sample, darker skin tone was associated with higher levels of perceived discrimination among Caribbean Black youth ( b = 0.48; 95% Confidence Interval (CI) = 0.07-0.89). A significant interaction was found between gender and skin tone ( b = 1.17; 95% CI = 0.49-1.86), suggesting a larger effect of skin tone on perceived discrimination for males than females. In stratified models, darker skin tone was associated with more perceived discrimination for males ( b = 1.20; 95% CI = 0.69-0.72) but not females ( b = 0.06; 95% CI = -0.42-0.55). Similar to the literature documenting male gender as a vulnerability factor to the effects of racial discrimination, we found that male but not female Caribbean Black youth with darker skin tones perceive more discrimination.

Discriminative stimulus properties of mitragynine (kratom) in rats.

PubMed

Harun, Norsyifa; Hassan, Zurina; Navaratnam, Visweswaran; Mansor, Sharif M; Shoaib, Mohammed

2015-07-01

Mitragynine (MG) is the primary active alkaloid extracted from the leaves of Mitragyna speciosa or kratom and exhibits pharmacological activities mediated by opioid receptors. The plant has been traditionally used for its opium and psychostimulant-like effects to increase work efficiency or as a substitute in the self-treatment of opiate addiction. The present study was performed to investigate the discriminative stimulus effects of MG in rats. The pharmacological mechanism of MG action and its derivative, 7-hydroxymitragynine (7-HMG) with a specific focus on opioid receptor involvement was examined in rats trained to discriminate morphine from vehicle. In order to study the dual actions of MG, the effect of cocaine substitution to the MG discriminative stimulus was also performed in MG-trained rats. Male Sprague Dawley rats were trained to discriminate MG from vehicle in a two-lever drug discrimination procedure under a tandem variable-interval (VI 60') fixed-ratio (FR 10) schedule of food reinforcement. Rats acquired the MG discrimination (15.0 mg/kg, i.p.) which was similar to the acquisition of morphine discrimination (5.0 mg/kg, i.p.) in another group of rats. MG substituted fully to the morphine discriminative stimulus in a dose-dependent manner, suggesting pharmacological similarities between the two drugs. The administration of 7-HMG derivative in 3.0 mg/kg (i.p.) dose engendered full generalisation to the morphine discriminative stimulus. In addition, the MG stimulus also partially generalised to cocaine (10.0 mg/kg, i.p.) stimulus. The present study demonstrates that the discriminative stimulus effect of MG possesses both opioid- and psychostimulant-like subjective effects.

Habituation of LG-mediated tailflip in the crayfish.

PubMed

Nagayama, Toshiki; Araki, Makoto

2015-06-01

Crayfish escape from threatening stimuli by tailflipping. If a stimulus is applied to the rear, crayfish escape up and forwards in a summersault maneuver that is mediated by the activation of lateral giant (LG) interneurons. The occurrence probability of LG-mediated tailflip, however, diminishes and habituates if a stimulus is repeatedly applied. Since crayfish have a relatively simple CNS with many identifiable neurons, crayfish represent a good animal to analyze the cellular basis of habituation. A reduction in the amplitude of the EPSP in the LGs, caused by direct chemical synaptic connection from sensory afferents by repetitive stimulations, is essential to bring about an inactivation of the LGs. The spike response of the LGs recovers within several minutes of habituation, but the LGs subsequently fail to spike when an additional stimulus is applied after specific periods following habituation. These results indicate that a decline in synaptic efficacy from the mechanosensory afferents recovers readily after a short delay, but then the excitability of the LGs themselves decreases. Furthermore, the processes underlying habituation are modulated depending on a social status. When two crayfish encounter each other, a winner-loser relationship is established. With a short interstimulus interval of 5 s, the rate of habituation of the LG in both socially dominant and subordinate crayfish becomes lower than in socially isolated animals. Serotonin and octopamine affect this social status-dependent modulation of habituation by means of activation of downstream second messenger system of cAMP and IP3 cascades, respectively.

A Concealed Information Test with multimodal measurement.

PubMed

Ambach, Wolfgang; Bursch, Stephanie; Stark, Rudolf; Vaitl, Dieter

2010-03-01

A Concealed Information Test (CIT) investigates differential physiological responses to deed-related (probe) vs. irrelevant items. The present study focused on the detection of concealed information using simultaneous recordings of autonomic and brain electrical measures. As a secondary issue, verbal and pictorial presentations were compared with respect to their influence on the recorded measures. Thirty-one participants underwent a mock-crime scenario with a combined verbal and pictorial presentation of nine items. The subsequent CIT, designed with respect to event-related potential (ERP) measurement, used a 3-3.5s interstimulus interval. The item presentation modality, i.e. pictures or written words, was varied between subjects; no response was required from the participants. In addition to electroencephalogram (EEG), electrodermal activity (EDA), electrocardiogram (ECG), respiratory activity, and finger plethysmogram were recorded. A significant probe-vs.-irrelevant effect was found for each of the measures. Compared to sole ERP measurement, the combination of ERP and EDA yielded incremental information for detecting concealed information. Although, EDA per se did not reach the predictive value known from studies primarily designed for peripheral physiological measurement. Presentation modality neither influenced the detection accuracy for autonomic measures nor EEG measures; this underpins the equivalence of verbal and pictorial item presentation in a CIT, regardless of the physiological measures recorded. Future studies should further clarify whether the incremental validity observed in the present study reflects a differential sensitivity of ERP and EDA to different sub-processes in a CIT. Copyright 2009 Elsevier B.V. All rights reserved.

Effect of acoustic similarity on short-term auditory memory in the monkey

PubMed Central

Scott, Brian H.; Mishkin, Mortimer; Yin, Pingbo

2013-01-01

Recent evidence suggests that the monkey’s short-term memory in audition depends on a passively retained sensory trace as opposed to a trace reactivated from long-term memory for use in working memory. Reliance on a passive sensory trace could render memory particularly susceptible to confusion between sounds that are similar in some acoustic dimension. If so, then in delayed matching-to-sample, the monkey’s performance should be predicted by the similarity in the salient acoustic dimension between the sample and subsequent test stimulus, even at very short delays. To test this prediction and isolate the acoustic features relevant to short-term memory, we examined the pattern of errors made by two rhesus monkeys performing a serial, auditory delayed match-to-sample task with interstimulus intervals of 1 s. The analysis revealed that false-alarm errors did indeed result from similarity-based confusion between the sample and the subsequent nonmatch stimuli. Manipulation of the stimuli showed that removal of spectral cues was more disruptive to matching behavior than removal of temporal cues. In addition, the effect of acoustic similarity on false-alarm response was stronger at the first nonmatch stimulus than at the second one. This pattern of errors would be expected if the first nonmatch stimulus overwrote the sample’s trace, and suggests that the passively retained trace is not only vulnerable to similarity-based confusion but is also highly susceptible to overwriting. PMID:23376550

Evidence for increased glutamatergic cortical facilitation in children and adolescents with major depressive disorder.

PubMed

Croarkin, Paul E; Nakonezny, Paul A; Husain, Mustafa M; Melton, Tabatha; Buyukdura, Jeylan S; Kennard, Betsy D; Emslie, Graham J; Kozel, F Andrew; Daskalakis, Zafiris J

2013-03-01

Converging lines of evidence implicate the glutamate and γ-aminobutyric acid neurotransmitter systems in the pathophysiology of major depressive disorder. Transcranial magnetic stimulation cortical excitability and inhibition paradigms have been used to assess cortical glutamatergic and γ-aminobutyric acid-mediated tone in adults with major depressive disorder, but not in children and adolescents. To compare measures of cortical excitability and inhibition with 4 different paradigms in a group of children and adolescents with major depressive disorder vs healthy controls. Cross-sectional study examining medication-free children and adolescents (aged 9-17 years) with major depressive disorder compared with healthy controls. Cortical excitability was assessed with motor threshold and intracortical facilitation measures. Cortical inhibition was measured with cortical silent period and intracortical inhibition paradigms. University-based child and adolescent psychiatry clinic and neurostimulation laboratory. Twenty-four participants with major depressive disorder and 22 healthy controls matched for age and sex. Patients with major depressive disorder were medication naive and had moderate to severe symptoms based on an evaluation with a child and adolescent psychiatrist and scores on the Children's Depression Rating Scale-Revised. Motor threshold, intracortical facilitation, cortical silent period, and intracortical inhibition. Compared with healthy controls, depressed patients had significantly increased intracortical facilitation at interstimulus intervals of 10 and 15 milliseconds bilaterally. There were no significant group differences in cortical inhibition measures. These findings suggest that major depressive disorder in children and adolescents is associated with increased intracortical facilitation and excessive glutamatergic activity.

Atypical auditory refractory periods in children from lower socio-economic status backgrounds: ERP evidence for a role of selective attention.

PubMed

Stevens, Courtney; Paulsen, David; Yasen, Alia; Neville, Helen

2015-02-01

Previous neuroimaging studies indicate that lower socio-economic status (SES) is associated with reduced effects of selective attention on auditory processing. Here, we investigated whether lower SES is also associated with differences in a stimulus-driven aspect of auditory processing: the neural refractory period, or reduced amplitude response at faster rates of stimulus presentation. Thirty-two children aged 3 to 8 years participated, and were divided into two SES groups based on maternal education. Event-related brain potentials were recorded to probe stimuli presented at interstimulus intervals (ISIs) of 200, 500, or 1000 ms. These probes were superimposed on story narratives when attended and ignored, permitting a simultaneous experimental manipulation of selective attention. Results indicated that group differences in refractory periods differed as a function of attention condition. Children from higher SES backgrounds showed full neural recovery by 500 ms for attended stimuli, but required at least 1000 ms for unattended stimuli. In contrast, children from lower SES backgrounds showed similar refractory effects to attended and unattended stimuli, with full neural recovery by 500 ms. Thus, in higher SES children only, one functional consequence of selective attention is attenuation of the response to unattended stimuli, particularly at rapid ISIs, altering basic properties of the auditory refractory period. Together, these data indicate that differences in selective attention impact basic aspects of auditory processing in children from lower SES backgrounds. Copyright © 2013 Elsevier B.V. All rights reserved.

Differential effects of uncertainty on LPP responses to emotional events during explicit and implicit anticipation.

PubMed

Lin, Huiyan; Liang, Jiafeng; Jin, Hua; Zhao, Dongmei

2018-07-01

Previous studies have investigated whether uncertainty influences neural responses to emotional events. The findings of such studies, particularly with respect to event-related potentials (ERPs), have been controversial due to several factors, such as the stimuli that serve as cues and the emotional content of the events. However, it is still unknown whether the effects of uncertainty on ERP responses to emotional events are influenced by anticipation patterns (e.g., explicit or implicit anticipation). To address this issue, participants in the present study were presented with anticipatory cues and then emotional (negative and neutral) pictures. The cues either did or did not signify the emotional content of the upcoming picture. In the inter-stimulus intervals between cues and pictures, participants were asked to estimate the expected probability of the occurrence of a specific emotional category of the subsequent picture based on a scale in the explicit anticipation condition, while in the implicit condition, participants were asked to indicate, using a number on a scale, which color was different from the others. The results revealed that in the explicit condition, uncertainty increased late positive potential (LPP) responses, particularly for negative pictures, whereas LPP responses were larger for certain negative pictures than for uncertain negative pictures in the implicit condition. The findings in the present study suggest that the anticipation pattern influences the effects of uncertainty when evaluation of negative events. Copyright © 2018 Elsevier B.V. All rights reserved.

Spectral mechanisms of spatially induced blackness: data and quantitative model.

PubMed

Shinomori, K; Schefrin, B E; Werner, J S

1997-02-01

Spectral efficiency functions and tests of additivity were obtained with three observers to identify possible chromatic contributions to spatially induced blackness. Stimuli consisted of a series of monochromatic (400-700 nm; 10-nm steps), 52-arcmin circular test lights surrounded by broadband (x = 0.31, y = 0.37), 63-138-arcmin annuli of fixed retinal illuminance. The stimuli were imaged on the fovea in Maxwellian view as 500-ms flashes with 10-s interstimulus intervals. Observers decreased the intensity of the test center until it was first perceived as completely black. Action spectra determined for two surround levels [2.5 and 3.5 log trolands] had three sensitivity peaks (at approximately 440, 540, and 600 nm), However, when monochromatic surrounds were adjusted to induce blackness in a broadband center, action spectra were unimodal and identical to functions obtained by heterochromatic flicker photometry. Tests of additivity revealed that when blackness is induced by broadband surround into a bichromatic center, there is an additivity failure of the cancellation type. This additivity failure indicates that blackness induction is influenced, in part, by signals from opponent-chromatic pathways. A quantitative model is presented to account for these data. This model assumes that blackness induction is determined by the ratio of responses to the stimulus center and the annulus, and while signals form the annulus are based only on achromatic information, responses from the center are based on both chromatic and achromatic properties of the stimulus.

Dysrhythmia of timed movements in Parkinson's disease and freezing of gait.

PubMed

Tolleson, Christopher M; Dobolyi, David G; Roman, Olivia C; Kanoff, Kristen; Barton, Scott; Wylie, Scott A; Kubovy, Michael; Claassen, Daniel O

2015-10-22

A well-established motor timing paradigm, the Synchronization-Continuation Task (SCT), quantifies how accurately participants can time finger tapping to a rhythmic auditory beat (synchronization phase) then maintain this rhythm after the external auditory cue is extinguished, where performance depends on an internal representation of the beat (continuation phase). In this study, we investigated the hypothesis that Parkinson's disease (PD) patients with clinical symptoms of freezing of gait (FOG) exhibit exaggerated motor timing deficits. We predicted that dysrhythmia is exacerbated when finger tapping is stopped temporarily and then reinitiated under the guidance of an internal representation of the beat. Healthy controls and PD patients with and without FOG performed the SCT with and without the insertion of a 7-s cessation of motor tapping between synchronization and continuation phases. With no interruption between synchronization and continuation phases, PD patients, especially those with FOG, showed pronounced motor timing hastening at the slowest inter-stimulus intervals during the continuation phase. The introduction of a gap prior to the continuation phase had a beneficial effect for healthy controls and PD patients without FOG, although patients with FOG continued to show pronounced and persistent motor timing hastening. Ratings of freezing of gait severity across the entire sample of PD tracked closely with the magnitude of hastening during the continuation phase. These results suggest that PD is accompanied by a unique dysrhythmia of measured movements, with FOG reflecting a particularly pronounced disruption to internal rhythmic timing. Copyright © 2015 Elsevier B.V. All rights reserved.

Stimulus-specific adaptation in a recurrent network model of primary auditory cortex

PubMed Central

2017-01-01

Stimulus-specific adaptation (SSA) occurs when neurons decrease their responses to frequently-presented (standard) stimuli but not, or not as much, to other, rare (deviant) stimuli. SSA is present in all mammalian species in which it has been tested as well as in birds. SSA confers short-term memory to neuronal responses, and may lie upstream of the generation of mismatch negativity (MMN), an important human event-related potential. Previously published models of SSA mostly rely on synaptic depression of the feedforward, thalamocortical input. Here we study SSA in a recurrent neural network model of primary auditory cortex. When the recurrent, intracortical synapses display synaptic depression, the network generates population spikes (PSs). SSA occurs in this network when deviants elicit a PS but standards do not, and we demarcate the regions in parameter space that allow SSA. While SSA based on PSs does not require feedforward depression, we identify feedforward depression as a mechanism for expanding the range of parameters that support SSA. We provide predictions for experiments that could help differentiate between SSA due to synaptic depression of feedforward connections and SSA due to synaptic depression of recurrent connections. Similar to experimental data, the magnitude of SSA in the model depends on the frequency difference between deviant and standard, probability of the deviant, inter-stimulus interval and input amplitude. In contrast to models based on feedforward depression, our model shows true deviance sensitivity as found in experiments. PMID:28288158

Anodal Direct Current Stimulation of the Cerebellum Reduces Cerebellar Brain Inhibition but Does Not Influence Afferent Input from the Hand or Face in Healthy Adults.

PubMed

Doeltgen, Sebastian H; Young, Jessica; Bradnam, Lynley V

2016-08-01

The cerebellum controls descending motor commands by outputs to primary motor cortex (M1) and the brainstem in response to sensory feedback. The cerebellum may also modulate afferent input en route to M1 and the brainstem. The objective of this study is to determine if anodal transcranial direct current stimulation (tDCS) to the cerebellum influences cerebellar brain inhibition (CBI), short afferent inhibition (SAI) and trigeminal reflexes (TRs) in healthy adults. Data from two studies evaluating effects of cerebellar anodal and sham tDCS are presented. The first study used a twin coil transcranial magnetic stimulation (TMS) protocol to investigate CBI and combined TMS and cutaneous stimulation of the digit to assess SAI. The second study evaluated effects on trigemino-cervical and trigemino-masseter reflexes using peripheral nerve stimulation of the face. Fourteen right-handed healthy adults participated in experiment 1. CBI was observed at baseline and was reduced by anodal cerebellar DCS only (P < 0.01). There was SAI at interstimulus intervals of 25 and 30 ms at baseline (both P < 0.0001), but cerebellar tDCS had no effect. Thirteen right-handed healthy adults participated in experiment 2. Inhibitory reflexes were evoked in the ipsilateral masseter and sternocleidomastoid muscles. There was no effect of cerebellar DCS on either reflex. Anodal DCS reduced CBI but did not change SAI or TRs in healthy adults. These results require confirmation in individuals with neurological impairment.

Task-dependent activation of distinct fast and slow(er) motor pathways during motor imagery.

PubMed

Keller, Martin; Taube, Wolfgang; Lauber, Benedikt

2018-02-22

Motor imagery and actual movements share overlapping activation of brain areas but little is known about task-specific activation of distinct motor pathways during mental simulation of movements. For real contractions, it was demonstrated that the slow(er) motor pathways are activated differently in ballistic compared to tonic contractions but it is unknown if this also holds true for imagined contractions. The aim of the present study was to assess the activity of fast and slow(er) motor pathways during mentally simulated movements of ballistic and tonic contractions. H-reflexes were conditioned with transcranial magnetic stimulation at different interstimulus intervals to assess the excitability of fast and slow(er) motor pathways during a) the execution of tonic and ballistic contractions, b) motor imagery of these contraction types, and c) at rest. In contrast to the fast motor pathways, the slow(er) pathways displayed a task-specific activation: for imagined ballistic as well as real ballistic contractions, the activation was reduced compared to rest whereas enhanced activation was found for imagined tonic and real tonic contractions. This study provides evidence that the excitability of fast and slow(er) motor pathways during motor imagery resembles the activation pattern observed during real contractions. The findings indicate that motor imagery results in task- and pathway-specific subliminal activation of distinct subsets of neurons in the primary motor cortex. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Differential brain activations in adult attention-deficit/ hyperactivity disorder subtypes: a counting Stroop functional MRI study.

PubMed

Shang, Chi-Yung; Sheng, Chia; Yang, Li-Kuang; Chou, Tai-Li; Gau, Susan Shur-Fen

2018-06-01

Although previous functional neuroimaging studies have found abnormal brain activations in individuals with attention deficit hyperactivity disorder (ADHD), little was known about distinct brain dysfunctions across different ADHD subtypes. The objective of the present study was to investigate the abnormal brain activations associated with two ADHD subtypes, predominantly inattentive (ADHD-PI) and combined (ADHD-C) subtypes. Twenty-five adults with ADHD-PI, 25 with ADHD-C, and 30 healthy controls (HC) participated in this study. The brain function of the participants were assessed by using the counting Stroop task inside the scanner and the Conners' Continuous Performance Test (CCPT) outside the scanner. The HC group showed greater activations in the caudate nucleus and inferior frontal gyrus (IFG) than the ADHD-PI and ADHD-C groups. The ADHD-PI group showed greater activations in the superior parietal lobule (SPL) than the ADHD-C group. In all participants with ADHD, we found negative correlations of activation in the left caudate and the left IFG with the standard deviation of the reaction time of the CCPT, and negative correlations of activation in the left SPL with the reaction time changes across different inter-stimulus intervals. Our results demonstrated altered brain activity in the frontostriatal networks of adults with ADHD-PI and the fronto-striato-parietal networks of adults with ADHD-C. Abnormalities in the parietal areas may represent the main difference between the ADHD-PI and ADHD-C subtypes.

Changes in complex spike activity during classical conditioning

PubMed Central

Rasmussen, Anders; Jirenhed, Dan-Anders; Wetmore, Daniel Z.; Hesslow, Germund

2014-01-01

The cerebellar cortex is necessary for adaptively timed conditioned responses (CRs) in eyeblink conditioning. During conditioning, Purkinje cells acquire pause responses or “Purkinje cell CRs” to the conditioned stimuli (CS), resulting in disinhibition of the cerebellar nuclei (CN), allowing them to activate motor nuclei that control eyeblinks. This disinhibition also causes inhibition of the inferior olive (IO), via the nucleo-olivary pathway (N-O). Activation of the IO, which relays the unconditional stimulus (US) to the cortex, elicits characteristic complex spikes in Purkinje cells. Although Purkinje cell activity, as well as stimulation of the CN, is known to influence IO activity, much remains to be learned about the way that learned changes in simple spike firing affects the IO. In the present study, we analyzed changes in simple and complex spike firing, in extracellular Purkinje cell records, from the C3 zone, in decerebrate ferrets undergoing training in a conditioning paradigm. In agreement with the N-O feedback hypothesis, acquisition resulted in a gradual decrease in complex spike activity during the conditioned stimulus, with a delay that is consistent with the long N-O latency. Also supporting the feedback hypothesis, training with a short interstimulus interval (ISI), which does not lead to acquisition of a Purkinje cell CR, did not cause a suppression of complex spike activity. In contrast, observations that extinction did not lead to a recovery in complex spike activity and the irregular patterns of simple and complex spike activity after the conditioned stimulus are less conclusive. PMID:25140129

Induction of motor associative plasticity in the posterior parietal cortex-primary motor network.

PubMed

Chao, Chi-Chao; Karabanov, Anke Ninija; Paine, Rainer; Carolina de Campos, Ana; Kukke, Sahana N; Wu, Tianxia; Wang, Han; Hallett, Mark

2015-02-01

There is anatomical and functional connectivity between the primary motor cortex (M1) and posterior parietal cortex (PPC) that plays a role in sensorimotor integration. In this study, we applied corticocortical paired-associative stimuli to ipsilateral PPC and M1 (parietal ccPAS) in healthy right-handed subjects to test if this procedure could modulate M1 excitability and PPC-M1 connectivity. One hundred and eighty paired transcranial magnetic stimuli to the PPC and M1 at an interstimulus interval (ISI) of 8 ms were delivered at 0.2 Hz. We found that parietal ccPAS in the left hemisphere increased the excitability of conditioned left M1 assessed by motor evoked potentials (MEPs) and the input-output curve. Motor behavior assessed by the Purdue pegboard task was unchanged compared with controls. At baseline, conditioning stimuli over the left PPC potentiated MEPs from left M1 when ISI was 8 ms. This interaction significantly attenuated at 60 min after left parietal ccPAS. Additional experiments showed that parietal ccPAS induced plasticity was timing-dependent, was absent if ISI was 100 ms, and could also be seen in the right hemisphere. Our results suggest that parietal ccPAS can modulate M1 excitability and PPC-M1 connectivity and is a new approach to modify motor excitability and sensorimotor interaction. Published by Oxford University Press 2013. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Effects of acute alcohol intoxication on automated processing: evidence from the double-step paradigm.

PubMed

Vorstius, Christian; Radach, Ralph; Lang, Alan R

2012-02-01

Reflexive and voluntary levels of processing have been studied extensively with respect to possible impairments due to alcohol intoxication. This study examined alcohol effects at the 'automated' level of processing essential to many complex visual processing tasks (e.g., reading, visual search) that involve ongoing modifications or reprogramming of well-practiced routines. Data from 30 participants (16 male) were collected in two counterbalanced sessions (alcohol vs. no-alcohol control; mean breath alcohol concentration = 68 mg/dL vs. 0 mg/dL). Eye movements were recorded during a double-step task where 75% of trials involved two target stimuli in rapid succession (inter-stimulus interval [ISI]=40, 70, or 100 ms) so that they could elicit two distinct saccades or eye movements (double steps). On 25% of trials a single target appeared. Results indicated that saccade latencies were longer under alcohol. In addition, the proportion of single-step responses and the mean saccade amplitude (length) of primary saccades decreased significantly with increasing ISI. The key novel finding, however, was that the reprogramming time needed to cancel the first saccade and adjust saccade amplitude was extended significantly by alcohol. The additional time made available by prolonged latencies due to alcohol was not utilized by the saccade programming system to decrease the number of two-step responses. These results represent the first demonstration of specific alcohol-induced programming deficits at the automated level of oculomotor processing.

Promoting Motor Cortical Plasticity with Acute Aerobic Exercise: A Role for Cerebellar Circuits

PubMed Central

Mang, Cameron S.; Brown, Katlyn E.; Neva, Jason L.; Snow, Nicholas J.; Campbell, Kristin L.; Boyd, Lara A.

2016-01-01

Acute aerobic exercise facilitated long-term potentiation-like plasticity in the human primary motor cortex (M1). Here, we investigated the effect of acute aerobic exercise on cerebellar circuits, and their potential contribution to altered M1 plasticity in healthy individuals (age: 24.8 ± 4.1 years). In Experiment   1, acute aerobic exercise reduced cerebellar inhibition (CBI) (n = 10, p = 0.01), elicited by dual-coil paired-pulse transcranial magnetic stimulation. In Experiment   2, we evaluated the facilitatory effects of aerobic exercise on responses to paired associative stimulation, delivered with a 25 ms (PAS25) or 21 ms (PAS21) interstimulus interval (n = 16 per group). Increased M1 excitability evoked by PAS25, but not PAS21, relies on trans-cerebellar sensory pathways. The magnitude of the aerobic exercise effect on PAS response was not significantly different between PAS protocols (interaction effect: p = 0.30); however, planned comparisons indicated that, relative to a period of rest, acute aerobic exercise enhanced the excitatory response to PAS25 (p = 0.02), but not PAS21 (p = 0.30). Thus, the results of these planned comparisons indirectly provide modest evidence that modulation of cerebellar circuits may contribute to exercise-induced increases in M1 plasticity. The findings have implications for developing aerobic exercise strategies to “prime” M1 plasticity for enhanced motor skill learning in applied settings. PMID:27127659

Effect of acoustic similarity on short-term auditory memory in the monkey.

PubMed

Scott, Brian H; Mishkin, Mortimer; Yin, Pingbo

2013-04-01

Recent evidence suggests that the monkey's short-term memory in audition depends on a passively retained sensory trace as opposed to a trace reactivated from long-term memory for use in working memory. Reliance on a passive sensory trace could render memory particularly susceptible to confusion between sounds that are similar in some acoustic dimension. If so, then in delayed matching-to-sample, the monkey's performance should be predicted by the similarity in the salient acoustic dimension between the sample and subsequent test stimulus, even at very short delays. To test this prediction and isolate the acoustic features relevant to short-term memory, we examined the pattern of errors made by two rhesus monkeys performing a serial, auditory delayed match-to-sample task with interstimulus intervals of 1 s. The analysis revealed that false-alarm errors did indeed result from similarity-based confusion between the sample and the subsequent nonmatch stimuli. Manipulation of the stimuli showed that removal of spectral cues was more disruptive to matching behavior than removal of temporal cues. In addition, the effect of acoustic similarity on false-alarm response was stronger at the first nonmatch stimulus than at the second one. This pattern of errors would be expected if the first nonmatch stimulus overwrote the sample's trace, and suggests that the passively retained trace is not only vulnerable to similarity-based confusion but is also highly susceptible to overwriting. Copyright © 2013 Elsevier B.V. All rights reserved.

The influence of iris color on the pupillary light reflex.

PubMed

Bergamin, O; Schoetzau, A; Sugimoto, K; Zulauf, M

1998-08-01

This study was carried out to investigate the effect of iris color on the pupillary light reflex (PLR) in normal healthy volunteers. Pupil perimetry was performed on 50 healthy volunteers with the Octopus 1-2-3 automated perimeter. Within the 30-deg visual field, 33 test locations were investigated four times. Stimulus parameters were Goldmann size V (1.72 degrees), intensity 1632 cd/m2, stimulus time 200 ms, background illumination 0 cd/m2, and interstimulus interval 3 s. Pupillometric parameters studied were initial pupil size, amplitude (magnitude of pupillary contraction), latency time, contraction time, pre-PLR movement, contraction velocity, and redilation velocity. Pupillometric parameters were investigated by analysis of variance by the independent variables blue and brown irides. Iris color (blue vs brown) influenced statistically significantly (P < 0.05) amplitude (0.504 mm vs 0.594 mm), contraction time (401 ms vs 407 ms), contraction velocity (13.75 mm2/s vs 16.01 mm2/s), and redilation velocity (4.80 mm2/s vs 5.66 mm2/s). Iris color did not influence initial pupil size (4.78 mm vs 4.83 mm), latency time (520 mm vs 521 ms), and pre-PLR movement (0.328 mm2/s vs 0.325 mm2/s). Pupillary contraction amplitude and velocity depended on iris color, whereas pupil size and latency time were independent of iris color. Therefore, iris color might be considered when, evaluating pupillary movements in pupil perimetry.

Self-reported experience of racial discrimination and health care use in New Zealand: results from the 2006/07 New Zealand Health Survey.

PubMed

Harris, Ricci; Cormack, Donna; Tobias, Martin; Yeh, Li-Chia; Talamaivao, Natalie; Minster, Joanna; Timutimu, Roimata

2012-05-01

We investigated whether reported experience of racial discrimination in health care and in other domains was associated with cancer screening and negative health care experiences. We used 2006/07 New Zealand Health Survey data (n = 12 488 adults). We used logistic regression to examine the relationship of reported experience of racial discrimination in health care (unfair treatment by a health professional) and in other domains (personal attack, unfair treatment in work and when gaining housing) to breast and cervical cancer screening and negative patient experiences adjusted for other variables. Racial discrimination by a health professional was associated with lower odds of breast (odds ratio [OR] = 0.37; 95% confidence interval [CI] = 0.14, 0.996) and cervical cancer (OR = 0.51; 95% CI = 0.30, 0.87) screening among Maori women. Racial discrimination by a health professional (OR = 1.57; 95% CI = 1.15, 2.14) and racial discrimination more widely (OR = 1.55; 95% CI = 1.35, 1.79) were associated with negative patient experiences for all participants. Experience of racial discrimination in both health care and other settings may influence health care use and experiences of care and is a potential pathway to poor health.

Stimulus generalization, discrimination learning, and peak shift in horses.

PubMed Central

Dougherty, D M; Lewis, P

1991-01-01

Using horses, we investigated three aspects of the stimulus control of lever-pressing behavior: stimulus generalization, discrimination learning, and peak shift. Nine solid black circles, ranging in size from 0.5 in. to 4.5 in. (1.3 cm to 11.4 cm) served as stimuli. Each horse was shaped, using successive approximations, to press a rat lever with its lip in the presence of a positive stimulus, the 2.5-in. (6.4-cm) circle. Shaping proceeded quickly and was comparable to that of other laboratory organisms. After responding was maintained on a variable-interval 30-s schedule, stimulus generalization gradients were collected from 2 horses prior to discrimination training. During discrimination training, grain followed lever presses in the presence of a positive stimulus (a 2.5-in circle) and never followed lever presses in the presence of a negative stimulus (a 1.5-in. [3.8-cm] circle). Three horses met a criterion of zero responses to the negative stimulus in fewer than 15 sessions. Horses given stimulus generalization testing prior to discrimination training produced symmetrical gradients; horses given discrimination training prior to generalization testing produced asymmetrical gradients. The peak of these gradients shifted away from the negative stimulus. These results are consistent with discrimination, stimulus generalization, and peak-shift phenomena observed in other organisms. PMID:1940765

The time course of learning during a vowel discrimination task by hearing-impaired and masked normal-hearing listeners

NASA Astrophysics Data System (ADS)

Davis, Carrie; Kewley-Port, Diane; Coughlin, Maureen

2002-05-01

Vowel discrimination was compared between a group of young, well-trained listeners with mild-to-moderate sensorineural hearing impairment (YHI), and a matched group of normal hearing, noise-masked listeners (YNH). Unexpectedly, discrimination of F1 and F2 in the YHI listeners was equal to or better than that observed in YNH listeners in three conditions of similar audibility [Davis et al., J. Acoust. Soc. Am. 109, 2501 (2001)]. However, in the same time interval, the YHI subjects completed an average of 55% more blocks of testing than the YNH group. New analyses were undertaken to examine the time course of learning during the vowel discrimination task, to determine whether performance was affected by number of trials. Learning curves for a set of vowels in the F1 and F2 regions showed no significant differences between the YHI and YNH listeners. Thus while the YHI subjects completed more trials overall, they achieved a level of discrimination similar to that of their normal-hearing peers within the same number of blocks. Implications of discrimination performance in relation to hearing status and listening strategies will be discussed. [Work supported by NIHDCD-02229.

Perceived discrimination and smoking among rural-to-urban migrant women working as restaurant/hotel workers and sex workers in China

PubMed Central

Shin, Sanghyuk S.; Wan, Xia; Wang, Qian; Raymond, H. Fisher; Liu, Huilin; Ding, Ding; Yang, Gonghuan; Novotny, Thomas E.

2013-01-01

Background Smoking may be a coping mechanism for psychosocial stress caused by discrimination. Methods We conducted a cross-sectional survey of rural-to-urban migrant women working as restaurant/hotel workers (RHWs) and those working as sex workers (FSWs) in 10 Chinese cities to investigate whether perceived discrimination is associated with smoking. We interviewed RHWs at medical examination clinics and FSWs at entertainment venues. Modified Poisson regression was used to estimate prevalence ratios. Results Of the 1696 RHWs and 532 FSWs enrolled, 155 (9.1%) and 63 (11.8%) reported perceived discrimination, respectively. Perceived discrimination was independently associated with ever tried smoking (prevalence ratio [PR], 1.71; 95% confidence interval [CI], 1.31–2.23) and current smoking (PR, 2.52; 95% CI, 1.32–4.79) among RHWs and ever tried smoking (PR, 1.36; 95% CI, 1.16–1.61) and current smoking (PR, 1.63; 95% CI, 1.28–2.06) among FSWs. Discussion Perceived discrimination is associated with higher prevalence of smoking among rural-to-urban migrant women in China. PMID:22389186

Racial discrimination, socioeconomic position, and illicit drug use among US Blacks.

PubMed

Carliner, Hannah; Delker, Erin; Fink, David S; Keyes, Katherine M; Hasin, Deborah S

2016-04-01

We assessed the relationship of self-reported racial discrimination with illicit drug use among US Blacks, and whether this differed by socioeconomic position (SEP). Among 6587 Black participants in Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (2004-2005), we used multiple logistic regression models to test the association between racial discrimination (measured on the 6-item Experiences of Discrimination scale) and past-year illicit drug use, and whether this differed by SEP. Racial discrimination was associated with past-year drug use [adjusted odds ratio (aOR) 2.32; 95 % confidence interval (CI) 1.70, 3.16] and with frequent drug use (aOR 1.91; 95 % CI 1.22, 2.99). For frequent illicit drug use, this relationship was stronger among higher SEP participants (aOR 3.55; 95 % CI 2.09, 6.02; p interaction < 0.01). The stronger association between racial discrimination and frequent illicit drug use among higher SEP Blacks suggests a complex interplay between disadvantaged and privileged statuses that merits further investigation. The finding of a significant difference by SEP highlights the importance of considering differences within heterogeneous race/ethnic groups when investigating health disparities.

The Link Between Everyday Discrimination, Healthcare Utilization, and Health Status Among a National Sample of Women.

PubMed

Fazeli Dehkordy, Soudabeh; Hall, Kelli S; Dalton, Vanessa K; Carlos, Ruth C

2016-10-01

Research has not adequately examined the potential negative effects of perceiving routine discrimination on general healthcare utilization or health status, especially among reproductive-aged women. We sought to evaluate the association between everyday discrimination, health service use, and perceived health among a national sample of women in the United States. Data were drawn from the Women's Healthcare Experiences and Preferences survey, a randomly selected, national probability sample of 1078 U.S. women aged 18-55 years. We examined associations between everyday discrimination (via a standardized scale) on frequency of health service utilization and perceived general health status using chi-square and multivariable logistic regression modeling. Compared with women who reported healthcare visits every 3 years or less (reference group), each one-point increase in discrimination score was associated with higher odds of having healthcare visits annually or more often (odds ratio [OR] = 1.36, confidence interval [95% CI] = 1.01-1.83). Additionally, each one-point increase in discrimination score was significantly associated with lower odds of having excellent/very good perceived health (OR = 0.65; 95% CI = 0.54-0.80). Perceived discrimination was associated with increased exposure to the healthcare setting among this national sample of women. Perceived discrimination was also inversely associated with excellent/very good perceived health status.

Perceived discrimination in health care and health status in a racially diverse sample.

PubMed

Hausmann, Leslie R M; Jeong, Kwonho; Bost, James E; Ibrahim, Said A

2008-09-01

Despite the surge of recent research on the association between perceived discrimination and health-related outcomes, few studies have focused on race-based discrimination encountered in health care settings. This study examined the prevalence of such discrimination, and its association with health status, for the 3 largest race/ethnic groups in the United States. Data were drawn from the 2004 Behavioral Risk Factor Surveillance System survey. The primary variables were perceived racial discrimination in health care and self-reported health status. Multivariable logistic regression was used to compare the prevalence of perceived discrimination for whites, African Americans, and Hispanics, and to examine the association between perceived discrimination and health status, controlling for sex, age, income, education, health care coverage, affordability of medical care, racial salience, and state. Perceived discrimination was reported by 2%, 5.2%, and 10.9% of whites, Hispanics, and African Americans, respectively. Only the difference between African Americans and whites remained significant in adjusted analyses [odds ratio (OR) = 3.22, 95% confidence interval (CI) = 2.46-4.21]. Racial/ethnic differences in perceived discrimination depended on income, education, health care coverage, and affordability of medical care. Perceived discrimination was associated with worse health status for the overall sample (OR = 1.71, 95% CI = 1.35-2.16). Stratified analyses revealed that this relationship was significant for whites (OR = 2.00, 95% CI = 1.45-2.77) and African Americans (OR = 1.95, 95% CI = 1.39-2.73), but not for Hispanics (OR = 0.55, 95% CI = 0.24-1.22). Perceived racial discrimination in health care is much more prevalent for African Americans than for whites or Hispanics. Furthermore, such discrimination is associated with worse health both for African Americans and for whites.

Perceived racial, socioeconomic and gender discrimination and its impact on contraceptive choice.

PubMed

Kossler, Karla; Kuroki, Lindsay M; Allsworth, Jenifer E; Secura, Gina M; Roehl, Kimberly A; Peipert, Jeffrey F

2011-09-01

The study was conducted to determine whether perceived racial, economic and gender discrimination has an impact on contraception use and choice of method. We analyzed the first 2,500 women aged 14-45 years enrolled in the Contraceptive CHOICE Project, a prospective cohort study aimed to reduce barriers to obtaining long-acting reversible contraception. Items from the "Experiences of Discrimination" (EOD) scale measured experienced race-, gender- and economic-based discrimination. Overall, 57% of women reported a history of discrimination. Thirty-three percent reported gender- or race-based discrimination, and 24% reported discrimination attributed to socioeconomic status (SES). Prior to study enrollment, women reporting discrimination were more likely to report any contraception use (61% vs. 52%, p<.001) but were more likely to use less effective methods (e.g., barrier methods, natural family planning or withdrawal; 41% vs. 32%, p<.001). In adjusted analyses, gender-, race- or SES-based discrimination were associated with increased current use of less effective methods [adjusted risk ratio (aRR) 1.22, 95% confidence interval (CI) 1.06-1.41; aRR 1.25, CI 1.08-1.45; aRR 1.23, CI 1.06-1.43, respectively]. After enrollment, 66% of women with a history of experience of discrimination chose a long-acting reversible contraceptive method (intrauterine device or implantable) and 35% chose a depo-medroxyprogesterone acetate or contraceptive pill, patch or ring. Discrimination negatively impacts a woman's use of contraception. However, after financial and structural barriers to contraceptive use were eliminated, women with EOD overwhelmingly selected effective methods of contraception. Future interventions to improve access and utilization of contraception should focus on eliminating barriers and targeting interventions that encompass race-, gender- and economic-based discrimination. Copyright © 2011 Elsevier Inc. All rights reserved.

Pulse-rate discrimination by cochlear-implant and normal-hearing listeners with and without binaural cues

PubMed Central

Carlyon, Robert P.; Long, Christopher J.; Deeks, John M.

2008-01-01

Experiment 1 measured rate discrimination of electric pulse trains by bilateral cochlear implant (CI) users, for standard rates of 100, 200, and 300 pps. In the diotic condition the pulses were presented simultaneously to the two ears. Consistent with previous results with unilateral stimulation, performance deteriorated at higher standard rates. In the signal interval of each trial in the dichotic condition, the standard rate was presented to the left ear and the (higher) signal rate was presented to the right ear; the non-signal intervals were the same as in the diotic condition. Performance in the dichotic condition was better for some listeners than in the diotic condition for standard rates of 100 and 200 pps, but not at 300 pps. It is concluded that the deterioration in rate discrimination observed for CI users at high rates cannot be alleviated by the introduction of a binaural cue, and is unlikely to be limited solely by central pitch processes. Experiment 2 performed an analogous experiment in which 300-pps acoustic pulse trains were bandpass filtered (3900-5400 Hz) and presented in a noise background to normal-hearing listeners. Unlike the results of experiment 1, performance was superior in the dichotic than in the diotic condition. PMID:18397032

Discrimination and common mental disorders of undergraduate students of the Universidade Federal de Santa Catarina.

PubMed

de Souza, Maria Vitória Cordeiro; Lemkuhl, Isabel; Bastos, João Luiz

2015-01-01

The pathogenic and consistent effect of discrimination on mental health has been largely documented in the literature. However, there are few studies measuring multiple types of discrimination, evaluating the existence of a dose-response relationship or investigating possible effect modifiers of such an association. To investigate the association between experiences of discrimination attributed to multiple reasons and common mental disorders, including the adjustment for potential confounders, assessment of dose-response relations, and examination of effect modifiers in undergraduate students from southern Brazil. In the first semester of 2012, 1,023 students from the Universidade Federal de Santa Catarina answered a self-administered questionnaire on socio-demographic characteristics, undergraduate course, experiences of discrimination and common mental disorders. Associations were analyzed through logistic regression models, estimation of Odds Ratios and 95% confidence intervals (95%CI). The study results showed that students reporting discrimination at high frequency and intensity were 4.4 (95%CI 1.6 - 12.4) times more likely to present common mental disorders. However, the relationship between discrimination and common mental disorders was protective among Electrical Engineering students, when compared to Accounting Sciences students who did not report discrimination. The findings suggest that the dose-response relationship between experiences of discrimination and common mental disorders reinforces the hypothetical causal nature of this association. Nevertheless, the modification of effect caused by the undergraduate course should be considered in future studies for a better understanding and measurement of both phenomena.

Racial and gender discrimination, early life factors, and chronic physical health conditions in midlife.

PubMed

McDonald, Jasmine A; Terry, Mary Beth; Tehranifar, Parisa

2014-01-01

Most studies of perceived discrimination have been cross-sectional and focused primarily on mental rather than physical health conditions. We examined the associations of perceived racial and gender discrimination reported in adulthood with early life factors and self-reported physician diagnosis of chronic physical health conditions. We used data from a racially diverse birth cohort of U.S. women (n = 168; average age, 41 years) with prospectively collected early life data (e.g., parental socioeconomic factors) and adult reported data on perceived discrimination, physical health conditions, and relevant risk factors. We performed modified robust Poisson regression owing to the high prevalence of the outcomes. Fifty percent of participants reported racial and 39% reported gender discrimination. Early life factors did not have strong associations with perceived discrimination. In adjusted regression models, participants reporting at least three experiences of gender or racial discrimination had a 38% increased risk of having at least one physical health condition (relative risk, 1.38; 95% confidence interval, 1.01-1.87). Using standardized regression coefficients, the magnitude of the association of having physical health condition(s) was larger for perceived discrimination than for being overweight or obese. Our results suggest a substantial chronic disease burden associated with perceived discrimination, which may exceed the impact of established risk factors for poor physical health. Copyright © 2014 Jacobs Institute of Women's Health. Published by Elsevier Inc. All rights reserved.

Observer weighting strategies in interaural time-difference discrimination and monaural level discrimination for a multi-tone complex

NASA Astrophysics Data System (ADS)

Dye, Raymond H.; Stellmack, Mark A.; Jurcin, Noah F.

2005-05-01

Two experiments measured listeners' abilities to weight information from different components in a complex of 553, 753, and 953 Hz. The goal was to determine whether or not the ability to adjust perceptual weights generalized across tasks. Weights were measured by binary logistic regression between stimulus values that were sampled from Gaussian distributions and listeners' responses. The first task was interaural time discrimination in which listeners judged the laterality of the target component. The second task was monaural level discrimination in which listeners indicated whether the level of the target component decreased or increased across two intervals. For both experiments, each of the three components served as the target. Ten listeners participated in both experiments. The results showed that those individuals who adjusted perceptual weights in the interaural time experiment could also do so in the monaural level discrimination task. The fact that the same individuals appeared to be analytic in both tasks is an indication that the weights measure the ability to attend to a particular region of the spectrum while ignoring other spectral regions. .

Chickadees discriminate contingency reversals presented consistently, but not frequently.

PubMed

McMillan, Neil; Hahn, Allison H; Congdon, Jenna V; Campbell, Kimberley A; Hoang, John; Scully, Erin N; Spetch, Marcia L; Sturdy, Christopher B

2017-07-01

Chickadees are high-metabolism, non-migratory birds, and thus an especially interesting model for studying how animals follow patterns of food availability over time. Here, we studied whether black-capped chickadees (Poecile atricapillus) could learn to reverse their behavior and/or to anticipate changes in reinforcement when the reinforcer contingencies for each stimulus were not stably fixed in time. In Experiment 1, we examined the responses of chickadees on an auditory go/no-go task, with constant reversals in reinforcement contingencies every 120 trials across daily testing intervals. Chickadees did not produce above-chance discrimination; however, when trained with a procedure that only reversed after successful discrimination, chickadees were able to discriminate and reverse their behavior successfully. In Experiment 2, we examined the responses of chickadees when reversals were structured to occur at the same time once per day, and chickadees were again able to discriminate and reverse their behavior over time, though they showed no reliable evidence of reversal anticipation. The frequency of reversals throughout the day thus appears to be an important determinant for these animals' performance in reversal procedures.

Mental health-related discrimination as a predictor of low engagement with mental health services.

PubMed

Clement, Sarah; Williams, Paul; Farrelly, Simone; Hatch, Stephani L; Schauman, Oliver; Jeffery, Debra; Henderson, R Claire; Thornicroft, Graham

2015-02-01

This study aimed to test the hypothesis that mental health-related discrimination experienced by adults receiving care from community mental health teams is associated with low engagement with services and to explore the pathways between these two variables. In this cross-sectional study, 202 adults registered with inner-city community mental health teams in the United Kingdom completed interviews assessing their engagement with mental health services (service user-rated version of the Service Engagement Scale), discrimination that they experienced because of mental illness, and other variables. Structural equation modeling was conducted to examine the relationship of experienced discrimination and service engagement with potential mediating and moderating variables, such as anticipated discrimination (Questionnaire on Anticipated Discrimination), internalized stigma (Internalized Stigma of Mental Illness Scale), stigma stress appraisal (Stigma Stress Appraisal), mistrust in services, the therapeutic relationship (Scale to Assess Therapeutic Relationships), difficulty disclosing information about one's mental health, and social support. Analyses controlled for age, race-ethnicity, and symptomatology. No evidence was found for a direct effect between experienced discrimination and service engagement. The total indirect effect of experienced discrimination on service engagement was statistically significant (coefficient=1.055, 95% confidence interval [CI]=.312-2.074, p=.019), mainly via mistrust in mental health services and therapeutic relationships (coefficient=.804, CI=.295-1.558, p=.019). A 1-unit increase in experienced discrimination via this pathway resulted in .804-unit of deterioration in service engagement. Findings indicate the importance of building and maintaining service users' trust in mental health services and in therapeutic relationships with professionals and countering the discrimination that may erode trust.

Comparison of Prolonged Atrial Electromechanical Delays with Different Definitions in the Discrimination of Patients with Non-Valvular Paroxysmal Atrial Fibrillation

PubMed Central

Lee, Dong Hyun; Choi, Sun Young; Seo, Jeong-Min; Choi, Jae-Hyuk; Cho, Young-Rak; Park, Kyungil; Kim, Moo Hyun; Kim, Young-Dae

2015-01-01

Background and Objectives Previous studies have evaluated atrial electromechanical delays (AEMDs) with a number of different definitions to discriminate patients with paroxysmal atrial fibrillation (PAF) from controls without PAF. However, their discriminative values for PAF have not previously been directly compared. Subjects and Methods A total of 65 PAF patients and 130 control subjects matched for age, sex, history of hypertension, and diabetes mellitus were selected. The AEMDi and AEMDp were defined as the time intervals from the initiation of the P wave on the surface electrocardiogram to the initiation and peak of the late diastolic transmitral inflow on pulsed wave Doppler images, respectively. The AEMDim and AEMDpm were defined as the time intervals from the initiation of the P wave on the surface electrocardiogram to the initiation and peak of the late diastolic lateral mitral annular motion on tissue Doppler images, respectively. Results There were no significant differences in the clinical characteristics between the two groups. All 4 AEMDs were consistently longer in the PAF group, and proven effective to differentiate the PAF patients from the controls. The AEMDi measurement had a larger area under the curve (AUC) than the other AEMDs, left atrial volume index, and P wave amplitude. However, the AEMDp, AEMDim, and AEMDpm measurements had AUCs similar to those of the left atrial volume index and P wave amplitude. Conclusion The findings suggest that the AEMDi is better than the other AEMDs for the discrimination of PAF patients from the controls. PMID:26617650

Immigration, Suicidal Ideation and Deliberate Self-Injury in the Boston Youth Survey 2006

PubMed Central

Borges, Guilherme; Azrael, Deborah; Almeida, Joanna; Johnson, Renee M.; Molnar, Beth E.; Hemenway, David; Miller, Matthew

2018-01-01

The prevalence and immigration-related correlates of deliberate self-injury (DSI) and suicidal ideation (SI) were estimated in a sample of Boston public high school students in 2006. Compared with U.S.-born youth, immigrant youth were not at increased risk for DSI or SI, even if they had experienced discrimination due to their ancestry. By contrast, U.S.-born youth who reported having been discriminated against because of their ancestry had an increased risk of deliberate self-injury (odds ratio [OR] = 3.1, 95% confidence interval [CI] = 1.6–5.9) and suicidal ideation (OR = 2.1, 95% CI = 1.2–3.8). The combination of being U.S.-born and experiencing ancestry-based discrimination identifies youth at increased risk for suicidal behavior. PMID:21470295

Discrimination Increases Suicidal Ideation in Black Adolescents Regardless of Ethnicity and Gender.

PubMed

Assari, Shervin; Moghani Lankarani, Maryam; Caldwell, Cleopatra Howard

2017-11-06

Discrimination is a common experience for Blacks across various developmental periods. Although much is known about the effect of discrimination on suicidal ideation of adults, less is known about the same association in Black youth. We examined the association between discrimination and suicidal ideation in a national sample of Black youth. We also explored gender and ethnic differences in this association. We used data from the National Survey of American Life-Adolescents (NSAL-A), 2003-2004. In total, 1170 Black adolescents entered the study. This number was composed of 810 African American and 360 Caribbean Black youth (aged 13 to 17 years). Demographic and socioeconomic factors were controls, perceived discrimination was the predictor, and lifetime suicidal ideation was the outcome. Logistic regression was used to test the association between perceived discrimination and suicidal ideation in the pooled sample, as well as based on ethnicity and gender. In the pooled sample of Black youth, higher perceived discrimination was associated with higher odds of suicidal ideation (Odds Ratio (OR) = 1.09; 95% Confidence Interval (CI) = 1.02-1.17). This association was significant net of age, ethnicity, gender, and socioeconomic status. We did not find interactions between perceived discrimination and ethnicity or gender on suicidal ideation. Perceived discrimination was associated with suicidal ideation in African Americans (CI = 1.09; 95% CI = 1.01-1.17) and Caribbean Blacks (CI = 1.16; 95% CI = 1.03-1.32), males (CI = 1.11; 95% CI = 1.00-1.25), and females (CI = 1.08; 95% CI = 1.00-1.16). Discrimination jeopardizes the mental health of Black youth. In a universal pattern, discrimination is associated with suicidal ideation in Black youth. More research is needed on this topic.

Darker Skin Tone Increases Perceived Discrimination among Male but Not Female Caribbean Black Youth

PubMed Central

Caldwell, Cleopatra Howard

2017-01-01

Background: Among most minority groups, males seem to report higher levels of exposure and vulnerability to racial discrimination. Although darker skin tone may increase exposure to racial discrimination, it is yet unknown whether skin tone similarly influences perceived discrimination among male and female Caribbean Black youth. Objective: The current cross-sectional study tests the role of gender on the effects of skin tone on perceived discrimination among Caribbean Black youth. Methods: Data came from the National Survey of American Life-Adolescent Supplement (NSAL-A), 2003–2004, which included 360 Caribbean Black youth (ages 13 to 17). Demographic factors (age and gender), socioeconomic status (SES; family income, income to needs ratio, and subjective SES), skin tone, and perceived everyday discrimination were measured. Linear regressions were used for data analysis. Results: In the pooled sample, darker skin tone was associated with higher levels of perceived discrimination among Caribbean Black youth (b = 0.48; 95% Confidence Interval (CI) = 0.07–0.89). A significant interaction was found between gender and skin tone (b = 1.17; 95% CI = 0.49–1.86), suggesting a larger effect of skin tone on perceived discrimination for males than females. In stratified models, darker skin tone was associated with more perceived discrimination for males (b = 1.20; 95% CI = 0.69–0.72) but not females (b = 0.06; 95% CI = −0.42–0.55). Conclusion: Similar to the literature documenting male gender as a vulnerability factor to the effects of racial discrimination, we found that male but not female Caribbean Black youth with darker skin tones perceive more discrimination. PMID:29231903

The mediating effect of discrimination, social support and hopelessness on self-rated health of Roma adolescents in Slovakia.

PubMed

Kolarcik, Peter; Geckova, Andrea Madarasova; Reijneveld, Sijmen A; Van Dijk, Jitse P

2015-11-19

According to the EU-MIDIS report on discrimination, Roma are the most discriminated against group in Europe. Research suggests that experiencing discrimination may itself be detrimental to health. The aim of this paper is to investigate whether discrimination, hopelessness and social support mediate differences in self-rated health (SRH) between Roma and non-Roma adolescents. We conducted a cross-sectional study among Roma from separated and segregated settlements in the eastern part of Slovakia (N = 330; mean age = 14.50; interview) and non-Roma adolescents (N = 722; mean age = 14.86; questionnaire); only non-missing data were used for analyses (n = 759). The effect of perceived discrimination, mother and father social support, and hopelessness on SRH was analysed as crude and adjusted for ethnicity, age, gender, parental education and social desirability. Mediating effects were separately assessed using the Sobel test and structural equation modelling. Roma adolescents reported poorer SRH and more discrimination, mother and father social support, hopelessness and social desirability. Roma ethnicity (Odds ratio/95 %-Confidence interval 3.27/2.40-4.47), discrimination (2.66/1.82-3.88), hopelessness (1.35/1.20-1.51) and mother (0.92/0.88-0.97) and father social support (0.96/0.93 - 0.997) were statistically significant predictors of poor SRH. Perceived discrimination, social support and hopelessness mediated the ethnicity-health association, with adjustment for social support increasing its strength and the other two variables decreasing it. Perceived discrimination, social support and hopelessness mediate a part of the association between Roma ethnicity and poor SRH, with discrimination and hopelessness being risk factors and social support a protective factor.

Perceived discrimination and depressive symptoms among US Latinos: the modifying role of educational attainment.

PubMed

Ward, Julia B; Feinstein, Lydia; Vines, Anissa I; Robinson, Whitney R; Haan, Mary N; Aiello, Allison E

2017-04-12

Despite growing evidence that discrimination may contribute to poor mental health, few studies have assessed this association among US Latinos. Furthermore, the interaction between discrimination and educational attainment in shaping Latino mental health is virtually unexplored. This study aims to examine the association between perceived discrimination and depressive symptoms and the modifying role of education among a population of Mexican-origin adults. We utilized population-based data from 629 Mexican-origin adults (mean age = 52.8 years) participating the Niños Lifestyle and Diabetes Study (2013-2014). Perceived discrimination was defined as responding 'sometimes' or 'often' to at least one item on the 9-item Everyday Discrimination Scale. High depressive symptoms were defined as scoring ≥10 on the CESD-10. We used log-binomial and linear-binomial models to estimate prevalence ratios (PR) and prevalence differences (PD), respectively, of high depressive symptoms for levels of perceived discrimination. Final models were adjusted for age, sex, education, cultural orientation, and nativity. General estimating equations were employed to account for within-family clustering. Prevalence of perceived discrimination and high depressive symptoms were 49.5% and 29.2%, respectively. Participants experiencing discrimination had higher depressive symptom prevalence than those never or rarely experiencing discrimination [PR = 1.94, 95% confidence interval (CI): 1.46-2.58; PD = 0.19, 95% CI: 0.12-0.27]. The strength of this association varied by education level. The association between discrimination and depressive symptoms was stronger among those with >12 years of education (PR = 2.69; PD = 0.24) compared to those with ≤12 years of education (PR = 1.36; PD = 0.09). US Latinos suffer a high burden of depressive symptoms, and discrimination may be an important driver of this burden. Our results suggest that effortful coping strategies, such as achieving high education despite high perceived discrimination, may magnify discrimination's adverse effect on Latino mental health.

Vibrotactile masking experiments reveal accelerated somatosensory processing in congenitally blind braille readers.

PubMed

Bhattacharjee, Arindam; Ye, Amanda J; Lisak, Joy A; Vargas, Maria G; Goldreich, Daniel

2010-10-27

Braille reading is a demanding task that requires the identification of rapidly varying tactile patterns. During proficient reading, neighboring characters impact the fingertip at ∼100 ms intervals, and adjacent raised dots within a character at 50 ms intervals. Because the brain requires time to interpret afferent sensorineural activity, among other reasons, tactile stimuli separated by such short temporal intervals pose a challenge to perception. How, then, do proficient Braille readers successfully interpret inputs arising from their fingertips at such rapid rates? We hypothesized that somatosensory perceptual consolidation occurs more rapidly in proficient Braille readers. If so, Braille readers should outperform sighted participants on masking tasks, which demand rapid perceptual processing, but would not necessarily outperform the sighted on tests of simple vibrotactile sensitivity. To investigate, we conducted two-interval forced-choice vibrotactile detection, amplitude discrimination, and masking tasks on the index fingertips of 89 sighted and 57 profoundly blind humans. Sighted and blind participants had similar unmasked detection (25 ms target tap) and amplitude discrimination (compared with 100 μm reference tap) thresholds, but congenitally blind Braille readers, the fastest readers among the blind participants, exhibited significantly less masking than the sighted (masker, 50 Hz, 50 μm; target-masker delays, ±50 and ±100 ms). Indeed, Braille reading speed correlated significantly and specifically with masking task performance, and in particular with the backward masking decay time constant. We conclude that vibrotactile sensitivity is unchanged but that perceptual processing is accelerated in congenitally blind Braille readers.

Vibrotactile masking experiments reveal accelerated somatosensory processing in congenitally blind Braille readers

PubMed Central

Bhattacharjee, Arindam; Ye, Amanda J.; Lisak, Joy A.; Vargas, Maria G.; Goldreich, Daniel

2010-01-01

Braille reading is a demanding task that requires the identification of rapidly varying tactile patterns. During proficient reading, neighboring characters impact the fingertip at about 100-ms intervals, and adjacent raised dots within a character at 50-ms intervals. Because the brain requires time to interpret afferent sensorineural activity, among other reasons, tactile stimuli separated by such short temporal intervals pose a challenge to perception. How, then, do proficient Braille readers successfully interpret inputs arising from their fingertips at such rapid rates? We hypothesized that somatosensory perceptual consolidation occurs more rapidly in proficient Braille readers. If so, Braille readers should outperform sighted participants on masking tasks, which demand rapid perceptual processing, but would not necessarily outperform the sighted on tests of simple vibrotactile sensitivity. To investigate, we conducted two-interval forced-choice vibrotactile detection, amplitude discrimination, and masking tasks on the index fingertips of 89 sighted and 57 profoundly blind humans. Sighted and blind participants had similar unmasked detection (25-ms target tap) and amplitude discrimination (compared to 100-micron reference tap) thresholds, but congenitally blind Braille readers, the fastest readers among the blind participants, exhibited significantly less masking than the sighted (masker: 50-Hz, 50-micron; target-masker delays ±50 and ±100 ms). Indeed, Braille reading speed correlated significantly and specifically with masking task performance, and in particular with the backward masking decay time constant. We conclude that vibrotactile sensitivity is unchanged, but that perceptual processing is accelerated in congenitally blind Braille readers. PMID:20980584

How to Calculate Renyi Entropy from Heart Rate Variability, and Why it Matters for Detecting Cardiac Autonomic Neuropathy.

PubMed

Cornforth, David J; Tarvainen, Mika P; Jelinek, Herbert F

2014-01-01

Cardiac autonomic neuropathy (CAN) is a disease that involves nerve damage leading to an abnormal control of heart rate. An open question is to what extent this condition is detectable from heart rate variability (HRV), which provides information only on successive intervals between heart beats, yet is non-invasive and easy to obtain from a three-lead ECG recording. A variety of measures may be extracted from HRV, including time domain, frequency domain, and more complex non-linear measures. Among the latter, Renyi entropy has been proposed as a suitable measure that can be used to discriminate CAN from controls. However, all entropy methods require estimation of probabilities, and there are a number of ways in which this estimation can be made. In this work, we calculate Renyi entropy using several variations of the histogram method and a density method based on sequences of RR intervals. In all, we calculate Renyi entropy using nine methods and compare their effectiveness in separating the different classes of participants. We found that the histogram method using single RR intervals yields an entropy measure that is either incapable of discriminating CAN from controls, or that it provides little information that could not be gained from the SD of the RR intervals. In contrast, probabilities calculated using a density method based on sequences of RR intervals yield an entropy measure that provides good separation between groups of participants and provides information not available from the SD. The main contribution of this work is that different approaches to calculating probability may affect the success of detecting disease. Our results bring new clarity to the methods used to calculate the Renyi entropy in general, and in particular, to the successful detection of CAN.

How to Calculate Renyi Entropy from Heart Rate Variability, and Why it Matters for Detecting Cardiac Autonomic Neuropathy

PubMed Central

Cornforth, David J.;  Tarvainen, Mika P.; Jelinek, Herbert F.

2014-01-01

Cardiac autonomic neuropathy (CAN) is a disease that involves nerve damage leading to an abnormal control of heart rate. An open question is to what extent this condition is detectable from heart rate variability (HRV), which provides information only on successive intervals between heart beats, yet is non-invasive and easy to obtain from a three-lead ECG recording. A variety of measures may be extracted from HRV, including time domain, frequency domain, and more complex non-linear measures. Among the latter, Renyi entropy has been proposed as a suitable measure that can be used to discriminate CAN from controls. However, all entropy methods require estimation of probabilities, and there are a number of ways in which this estimation can be made. In this work, we calculate Renyi entropy using several variations of the histogram method and a density method based on sequences of RR intervals. In all, we calculate Renyi entropy using nine methods and compare their effectiveness in separating the different classes of participants. We found that the histogram method using single RR intervals yields an entropy measure that is either incapable of discriminating CAN from controls, or that it provides little information that could not be gained from the SD of the RR intervals. In contrast, probabilities calculated using a density method based on sequences of RR intervals yield an entropy measure that provides good separation between groups of participants and provides information not available from the SD. The main contribution of this work is that different approaches to calculating probability may affect the success of detecting disease. Our results bring new clarity to the methods used to calculate the Renyi entropy in general, and in particular, to the successful detection of CAN. PMID:25250311

Saliency affects feedforward more than feedback processing in early visual cortex.

PubMed

Emmanouil, Tatiana Aloi; Avigan, Philip; Persuh, Marjan; Ro, Tony

2013-07-01

Early visual cortex activity is influenced by both bottom-up and top-down factors. To investigate the influences of bottom-up (saliency) and top-down (task) factors on different stages of visual processing, we used transcranial magnetic stimulation (TMS) of areas V1/V2 to induce visual suppression at varying temporal intervals. Subjects were asked to detect and discriminate the color or the orientation of briefly-presented small lines that varied on color saliency based on color contrast with the surround. Regardless of task, color saliency modulated the magnitude of TMS-induced visual suppression, especially at earlier temporal processing intervals that reflect the feedforward stage of visual processing in V1/V2. In a second experiment we found that our color saliency effects were also influenced by an inherent advantage of the color red relative to other hues and that color discrimination difficulty did not affect visual suppression. These results support the notion that early visual processing is stimulus driven and that feedforward and feedback processing encode different types of information about visual scenes. They further suggest that certain hues can be prioritized over others within our visual systems by being more robustly represented during early temporal processing intervals. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of leaf age within growth stages of pepper and sorghum plants on leaf thickness, water, chlorophyll, and light reflectance. [in spectral vegetation discrimination

NASA Technical Reports Server (NTRS)

Gausman, H. W.; Cardenas, R.; Berumen, A.

1974-01-01

Pepper and sorghum plants (characterized by porous and compact leaf mesophylls, respectively) were used to study the influence of leaf age on light reflectance. Measurements were limited to the upper five nodal positions within each growth stage, since upper leaves make up most of the reflectance surfaces remotely sensed. The increase in leaf thickness and water content with increasing leaf age was taken into consideration, since each of these factors affects the reflectance as well as the selection of spectral wavelength intervals for optimum discrimination of vegetation.

Racial Discrimination and Racial Identity Attitudes in Relation to Self-Rated Health and Physical Pain and Impairment Among Two-Spirit American Indians/Alaska Natives

PubMed Central

Walters, Karina L.

2009-01-01

Objectives. We examined associations between racial discrimination and actualization, defined as the degree of positive integration between self-identity and racial group identity, and self-rated health and physical pain and impairment. Methods. We used logistic regressions to analyze data from 447 gay, lesbian, bisexual, and other sexual-minority American Indians/Alaska Natives. Results. Greater self-reported discrimination was associated with higher odds of physical pain and impairment (odds ratio [OR] = 1.42; 95% confidence interval [CI] = 1.13, 1.78); high levels of actualization were associated with lower odds of physical pain and impairment (OR = 0.59; 95% CI = 0.35, 0.99) and self-rated fair or poor health (OR = 0.54; 95% CI = 0.32, 0.90). Actualization also moderated the influence of discrimination on self-rated health (t = –2.33; P = .020). Discrimination was positively associated with fair or poor health among participants with low levels of actualization, but this association was weak among those with high levels of actualization. Conclusions. Among two-spirit American Indians/Alaska Natives, discrimination may be a risk factor for physical pain and impairment and for fair or poor self-rated health among those with low levels of actualization. Actualization may protect against physical pain and impairment and poor self-rated health and buffer the negative influence of discrimination. PMID:19218182

Self-Reported Experience of Racial Discrimination and Health Care Use in New Zealand: Results From the 2006/07 New Zealand Health Survey

PubMed Central

Cormack, Donna; Tobias, Martin; Yeh, Li-Chia; Talamaivao, Natalie; Minster, Joanna; Timutimu, Roimata

2012-01-01

Objectives. We investigated whether reported experience of racial discrimination in health care and in other domains was associated with cancer screening and negative health care experiences. Methods. We used 2006/07 New Zealand Health Survey data (n = 12 488 adults). We used logistic regression to examine the relationship of reported experience of racial discrimination in health care (unfair treatment by a health professional) and in other domains (personal attack, unfair treatment in work and when gaining housing) to breast and cervical cancer screening and negative patient experiences adjusted for other variables. Results. Racial discrimination by a health professional was associated with lower odds of breast (odds ratio [OR] = 0.37; 95% confidence interval [CI] = 0.14, 0.996) and cervical cancer (OR = 0.51; 95% CI = 0.30, 0.87) screening among Maori women. Racial discrimination by a health professional (OR = 1.57; 95% CI = 1.15, 2.14) and racial discrimination more widely (OR = 1.55; 95% CI = 1.35, 1.79) were associated with negative patient experiences for all participants. Conclusions. Experience of racial discrimination in both health care and other settings may influence health care use and experiences of care and is a potential pathway to poor health. PMID:22420811

The association between discrimination and depressive symptoms among older African Americans: the role of psychological and social factors.

PubMed

Nadimpalli, Sarah B; James, Bryan D; Yu, Lei; Cothran, Fawn; Barnes, Lisa L

2015-01-01

BACKGROUND/STUDY CONTEXT: Several studies have demonstrated a link between perceived discrimination and depression in ethnic minority groups, yet most have focused on younger or middle-aged African Americans and little is known about factors that may moderate the relationship. Participants were 487 older African Americans (60-98 years old) enrolled in the Minority Aging Research Study. Discrimination, depressive symptoms, and psychological and social resources were assessed via interview using validated measures. Ordinal logistic regression models were used to assess (1) the main relationship between discrimination and depression and (2) resilience, purpose in life, social isolation, and social networks as potential moderators of this relationship. In models adjusted for age, sex, education, and income, perceived discrimination was positively associated with depressive symptoms (odds ratio [OR]: 1.20, 95% confidence interval [CI]: 1.10-1.31; p < .001). However, there was no evidence of effect modification by resilience, purpose in life, social isolation, or social networks (all ps ≤ .05). Findings provide support for accumulating evidence on the adverse mental health effects of discrimination among older African Americans. Because the association was not modified by psychological or social factors, these findings do not support a role for a buffering effect of resources on discrimination and depressive symptoms. Further studies are needed to examine a wider range of coping resources among older adults.

Discriminative stimulus properties of indorenate, a serotonin agonist.

PubMed Central

Velázquez-Martínez, D N; López Cabrera, M; Sánchez, H; Ramírez, J I; Hong, E

1999-01-01

OBJECTIVE: To determine whether indorenate, a serotonin-receptor agonist, can exert discriminative control over operant responses, to establish the temporal course of discriminative control and to compare its stimulus properties to a (5-HT)IA receptor agonist. [3H]-8-hydroxy-2-(di-N-propylamino) tetralin (8-OH-DPAT). DESIGN: Prospective animal study. ANIMALS: Ten male Wistar rats. INTERVENTIONS: Rats were trained to press either of 2 levers for sucrose solution according to a fixed ratio schedule, which was gradually increased. Rats were given injections of either indorenate or saline solution during discrimination training. Once they had achieved an 83% accuracy rate, rats underwent generalization tests after having received a different dose of indorenate, the training dose of indorenate at various intervals before the test, various doses of 8-OH-DPT, or NAN-190 administered before indorenate or 8-OH-DPAT. OUTCOME MEASURES: Distribution of responses between the 2 levers before the first reinforcer of the session, response rate for all the responses in the session, and a discrimination index that expressed the drug-appropriate responses as a proportion of the total responses. RESULTS: Indorenate administration resulted in discriminative control over operant responses, maintained at fixed ratio 10, at a dose of 10.0 mg/kg (but not 3.0 mg/kg). When the interval between the administration of indorenate and the start of the session was varied, the time course of its cue properties followed that of its described effects on 5-HT turnover. In generalization tests, the discrimination index was a function of the dose of indorenate employed; moreover, administration of 8-OH-DPAT (from 0.1 to 1.0 mg/kg) fully mimicked the stimulus properties of indorenate in a dose-dependent way. The (5-HT)IA antagonist NAN-190 prevented the stimulus generalization from indorenate to 8-OH-DPAT. Also, NAN-190 antagonized the stimulus control of indorenate when administered 45 minutes before the session, but not when administered 105 minutes before the session (i.e., 15 minutes before the administration of indorenate). CONCLUSION: (5-HT)IA receptors are of relevance to the stimulus function of indorenate. However, other receptor subtypes may also be involved. Hence, other agonists and specific antagonists should be studied before definite conclusions are drawn. PMID:10212554

Mechanisms of impulsive choice: III. The role of reward processes

PubMed Central

Marshall, Andrew T.

2015-01-01

Two experiments examined the relationship between reward processing and impulsive choice. In Experiment 1, rats chose between a smaller-sooner (SS) reward (1 pellet, 10 s) and a larger-later (LL) reward (1, 2, and 4 pellets, 30 s). The rats then experienced concurrent variable-interval 30-s schedules with variations in reward magnitude to evaluate reward magnitude discrimination. LL choice behavior positively correlated with reward magnitude discrimination. In Experiment 2, rats chose between an SS reward (1 pellet, 10 s) and an LL reward (2 and 4 pellets, 30 s). The rats then received either a reward intervention which consisted of concurrent fixed-ratio schedules associated with different magnitudes to improve their reward magnitude discrimination, or a control task. All rats then experienced a post-intervention impulsive choice task followed by a reward magnitude discrimination task to assess intervention efficacy. The rats that received the intervention exhibited increases in post-intervention LL choice behavior, and made more responses for larger-reward magnitudes in the reward magnitude discrimination task, suggesting that the intervention heightened sensitivities to reward magnitude. The results suggest that reward magnitude discrimination plays a key role in individual differences in impulsive choice, and could be a potential target for further intervention developments. PMID:26506254

Experiences of racial discrimination and relation to sexual risk for HIV among a sample of urban black and African American men.

PubMed

Reed, E; Santana, M C; Bowleg, L; Welles, S L; Horsburgh, C R; Raj, A

2013-04-01

This study aimed to examine racial discrimination and relation to sexual risk for HIV among a sample of urban black and African American men. Participants of this cross-sectional study were black and African American men (N = 703) between the ages of 18 and 65 years, recruited from four urban clinical sites in the northeast. Multivariate logistic regression models were used to analyze the relation of reported racial discrimination to the following: (1) sex trade involvement, (2) recent unprotected sex, and (3) reporting a number of sex partners in the past 12 months greater than the sample average. The majority of the sample (96%) reported racial discrimination. In adjusted analyses, men reporting high levels of discrimination were significantly more likely to report recent sex trade involvement (buying and/or selling) (adjusted odds ratio (AOR) range = 1.7-2.3), having recent unprotected vaginal sex with a female partner (AOR = 1.4, 95% confidence interval (CI), 1.1-2.0), and reporting more than four sex partners in the past year (AOR = 1.4, 95% CI, 1.1-1.9). Findings highlight the link between experiences of racial discrimination and men's sexual risk for HIV.

Social determinants of self-perceived discrimination in Spain.

PubMed

Gil-González, D; Vives-Cases, C; Borrell, C; Agudelo-Suárez, A A; Álvarez-Dardet, C

2013-03-01

To analyse the association between self-perceived discrimination and social determinants (social class, gender, country of origin) in Spain, and further to describe contextual factors which contribute to self-perceived discrimination. Cross-sectional design using data from the Spanish National Health Survey (2006). The dependent variable was self-perceived discrimination, and independent and stratifying variables were sociodemographic characteristics (e.g. sex, social class, country of origin, educational level). Logistic regression was used. The prevalence of self-perceived discrimination was 4.2% for men and 6.3% for women. The likelihood of self-perceived discrimination was higher in people who originated from low-income countries: men, odds ratio (OR) 5.59 [95% confidence interval (CI) 4.55-6.87]; women, OR 4.06 (95% CI 3.42-4.83). Women were more likely to report self-perceived discrimination by their partner at home than men [OR 8.35 (95% CI 4.70-14.84)]. The likelihood of self-perceived discrimination when seeking work was higher among people who originated from low-income countries than their Spanish counterparts: men, OR 13.65 (95% CI 9.62-19.35); women, OR 10.64 (95% CI 8.31-13.62). In comparison with Spaniards, male white-collar workers who originated from low-income countries [OR 11.93 (95% CI 8.26-17.23)] and female blue-collar workers who originated from low-income countries (OR 1.6 (95% CI 1.08-2.39)] reported higher levels of self-perceived discrimination. Self-perceived discrimination is distributed unevenly in Spain and interacts with social inequalities. This particularly affects women and immigrants. Copyright © 2012 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Magnitude and Temporal Variability of Inter-stimulus EEG Modulate the Linear Relationship Between Laser-Evoked Potentials and Fast-Pain Perception

PubMed Central

Li, Linling; Huang, Gan; Lin, Qianqian; Liu, Jia; Zhang, Shengli; Zhang, Zhiguo

2018-01-01

The level of pain perception is correlated with the magnitude of pain-evoked brain responses, such as laser-evoked potentials (LEP), across trials. The positive LEP-pain relationship lays the foundation for pain prediction based on single-trial LEP, but cross-individual pain prediction does not have a good performance because the LEP-pain relationship exhibits substantial cross-individual difference. In this study, we aim to explain the cross-individual difference in the LEP-pain relationship using inter-stimulus EEG (isEEG) features. The isEEG features (root mean square as magnitude and mean square successive difference as temporal variability) were estimated from isEEG data (at full band and five frequency bands) recorded between painful stimuli. A linear model was fitted to investigate the relationship between pain ratings and LEP response for fast-pain trials on a trial-by-trial basis. Then the correlation between isEEG features and the parameters of LEP-pain model (slope and intercept) was evaluated. We found that the magnitude and temporal variability of isEEG could modulate the parameters of an individual's linear LEP-pain model for fast-pain trials. Based on this, we further developed a new individualized fast-pain prediction scheme, which only used training individuals with similar isEEG features as the test individual to train the fast-pain prediction model, and obtained improved accuracy in cross-individual fast-pain prediction. The findings could help elucidate the neural mechanism of cross-individual difference in pain experience and the proposed fast-pain prediction scheme could be potentially used as a practical and feasible pain prediction method in clinical practice. PMID:29904336

Mammalian Odor Information Recognition by Implanted Microsensor Array in vivo

NASA Astrophysics Data System (ADS)

Zhou, Jun; Dong, Qi; Zhuang, Liujing; Liu, Qingjun; Wang, Ping

2011-09-01

The mammalian olfactory system has an exquisite capacity to rapidly recognize and discriminate thousands of distinct odors in our environment. Our research group focus on reading information from olfactory bulb circuit of anethetized Sprague-Dawley rat and utilize artificial recognition system for odor discrimination. After being stimulated by three odors with concentration of 10 μM to rat nose, the response of mitral cells in olfactory bulb is recorded by eight channel microwire sensor array. In 20 sessions with 3 animals, we obtained 30 discriminated individual cells recordings. The average firing rates of the cells are Isoamyl acetate 26 Hz, Methoxybenzene 16 Hz, and Rose essential oil 11 Hz. By spike sorting, we detect peaks and analyze the interspike interval distribution. Further more, principal component analysis is applied to reduce the dimensionality of the data sets and classify the response.

Automated segmentation of retinal blood vessels and identification of proliferative diabetic retinopathy

NASA Astrophysics Data System (ADS)

Jelinek, Herbert F.; Cree, Michael J.; Leandro, Jorge J. G.; Soares, João V. B.; Cesar, Roberto M.; Luckie, A.

2007-05-01

Proliferative diabetic retinopathy can lead to blindness. However, early recognition allows appropriate, timely intervention. Fluorescein-labeled retinal blood vessels of 27 digital images were automatically segmented using the Gabor wavelet transform and classified using traditional features such as area, perimeter, and an additional five morphological features based on the derivatives-of-Gaussian wavelet-derived data. Discriminant analysis indicated that traditional features do not detect early proliferative retinopathy. The best single feature for discrimination was the wavelet curvature with an area under the curve (AUC) of 0.76. Linear discriminant analysis with a selection of six features achieved an AUC of 0.90 (0.73-0.97, 95% confidence interval). The wavelet method was able to segment retinal blood vessels and classify the images according to the presence or absence of proliferative retinopathy.

Molindone: effects in pigeons responding under conditional discrimination tasks.

PubMed

Picker, M J; Cleary, J P; Berens, K; Oliveto, A H; Dykstra, L A

1989-02-01

Pigeons were trained to respond under three conditional discrimination procedures; 1) a fixed-consecutive-number procedure with (FCN 8-SD) and without (FCN 8) an added external discriminative stimulus, 2) a delayed matching-to-sample (DMTS) procedure using 0-sec, 2-sec and 8-sec delay intervals, and 3) a repeated acquisition of behavioral chains (RA) procedure using a four-link response chain with three stimulus keys. The atypical neuroleptic agent molindone decreased accuracy under the FCN 8 at doses that had no effect on accuracy under the FCN 8-SD. Under the DMTS procedure, molindone-induced decreases in accuracy were directly related to the delay interval, with the largest relative decrements obtained at the 8-sec delay and the smallest at the 0-sec delay. Under the RA procedure, molindone decreased accuracy at doses that had little or no effect on the number of correct responses emitted. Relative to control values, molindone-induced decreases in accuracy were smallest under the DMTS and FCN 8-SD procedures and largest under the FCN 8 and RA procedures. The differential effects obtained with molindone under each of these procedures illustrate the need to employ a variety of assays when determining the behavioral actions of neuroleptics. In addition, this battery of behavioral tests may provide a useful tool for assessing the different neurochemical actions of neuroleptic compounds.

MTB-DR-RIF 9G test: Detection and discrimination of tuberculosis and multi-drug resistant tuberculosis strains.

PubMed

Song, Keum-Soo; Nimse, Satish Balasaheb; Cho, Nam Hoon; Sung, Nackmoon; Kim, Hee-Jin; Yang, Jeongseong; Kim, Taisun

2015-12-01

This report describes the evaluation of the novel MTB-DR-RIF 9G test for the accurate detection and discrimination of Mycobacterium tuberculosis (MTB) and rifampicin-resistant M. tuberculosis (MTB-DR-RIF) in the clinical samples. The procedure included the amplification of a nucleotide fragment of the rpoB gene of the MTB and MTB-DR-RIF strains and their hybridization with the immobilized probes. The MTB-DR-RIF 9G test was evaluated for its ability to detect and discriminate MTB and MTB-DR-RIF strains in 113 known clinical samples. The accuracy of the MTB-DR-RIF 9G test was determined by comparing its results with sequencing analysis and drug susceptibility testing. The sensitivity and specificity of the MTB-DR-RIF 9G test at 95% confidence interval were found to be 95.4% (89.5-98.5) and 100% (69.2-100), respectively. The positive predictive value and negative predictive value of the MTB-DR-RIF 9G test at 95% confidence interval were found to be 100% (85.0-95.9) and 66.7% (38.4-88.18), respectively. Sequencing analysis of all samples indicated that the mutations present in the regions identified with the MTB-DR-RIF 9G assay can be detected accurately. Copyright © 2015 Elsevier Ltd. All rights reserved.

Drug discrimination under two concurrent fixed-interval fixed-interval schedules.

PubMed

McMillan, D E; Li, M

2000-07-01

Pigeons were trained to discriminate 5.0 mg/kg pentobarbital from saline under a two-key concurrent fixed-interval (FI) 100-s FI 200-s schedule of food presentation, and later tinder a concurrent FI 40-s FI 80-s schedule, in which the FI component with the shorter time requirement reinforced responding on one key after drug administration (pentobarbital-biased key) and on the other key after saline administration (saline-biased key). After responding stabilized under the concurrent FI 100-s FI 200-s schedule, pigeons earned an average of 66% (after pentobarbital) to 68% (after saline) of their reinforcers for responding under the FI 100-s component of the concurrent schedule. These birds made an average of 70% of their responses on both the pentobarbital-biased key after the training dose of pentobarbital and the saline-biased key after saline. After responding stabilized under the concurrent FI 40-s FI 80-s schedule, pigeons earned an average of 67% of their reinforcers for responding under the FI 40 component after both saline and the training dose of pentobarbital. These birds made an average of 75% of their responses on the pentobarbital-biased key after the training dose of pentobarbital, but only 55% of their responses on the saline-biased key after saline. In test sessions preceded by doses of pentobarbital, chlordiazepoxide, ethanol, phencyclidine, or methamphetamine, the dose-response curves were similar under these two concurrent schedules. Pentobarbital, chlordiazepoxide, and ethanol produced dose-dependent increases in responding on the pentobarbital-biased key as the doses increased. For some birds, at the highest doses of these drugs, the dose-response curve turned over. Increasing doses of phencyclidine produced increased responding on the pentobarbital-biased key in some, but not all, birds. After methamphetamine, responding was largely confined to the saline-biased key. These data show that pigeons can perform drug discriminations under concurrent schedules in which the reinforcement frequency under the schedule components differs only by a factor of two, and that when other drugs are substituted for the training drugs they produce dose-response curves similar to the curves produced by these drugs under other concurrent interval schedules.

Can listeners hear who is singing? What is the pitch bandwidth of singer discrimination in untrained listeners?

PubMed

Erickson, Molly L

2012-05-01

This study sought to determine the pitch bandwidth of singer discrimination based on singer gender, pitch range, and same-different voice category. Repeated measures factorial design. This study used a forced-choice paradigm, where listeners heard two different singers (singer 1 and singer 2) producing /ɑ/ at an identical pitch and an unknown singer (either singer 1 or singer 2) producing /ɑ/ at a different pitch. It was the listener's task to identify which singer (singer 1 or singer 2) was the unknown singer. Two baritones and two tenors were recorded producing /ɑ/ at the pitches C3, E3, G3, B3, D4, and F4. Two sopranos and two mezzo-sopranos were recorded producing /ɑ/ at the pitches C4, E4, G4, B4, D5, and F5. For each group of stimuli, male and female, all possible pairs of singers were constructed for the lowest pitch (C2 or C3, respectively) and highest pitch (F4 or F5, respectively). The unknown singer was varied across the remaining pitches. For between category comparisons, the ability to discriminate singers diminished monotonically with pitch interval, reaching below chance levels between the intervals of the 9th and 11th. For within category comparisons, it was much harder to discriminate singers across pitch, particularly when the voices were female. Timbre is not perceived as invariant across the entire singing range, and the bandwidth of this timbre invariance depends on multiple factors, including pitch range, gender, and same-different voice category. Copyright © 2012 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

Reference intervals and discrimination values of the Lanthony desaturated D-15 panel test in young to middle-aged Japanese army officials: the Okubo Color Study Report 1.

PubMed

Shoji, T; Sakurai, Y; Chihara, E; Nishikawa, S; Omae, K

2009-06-01

To better understand the reference values and adequate discrimination values of colour vision function with described quantitative systems for the Lanthony desaturated D-15 panel (D-15DS). A total of 1042 Japanese male officials were interviewed and underwent testing using Ishihara pseudoisochromatic plates, standard pseudoisochromatic plates part 2, and the D-15DS. The Farnsworth-Munsell (F-M) 100-hue test and the criteria of Verriest et al were used as definitive tests. Outcomes of the D-15DS were calculated using Bowman's Colour Confusion Index (CCI). The study design included two criteria. In criterion A, subjects with current or past ocular disease and a best-corrected visual acuity less than 0.7 on a decimal visual acuity chart were excluded. In criterion B, among subjects who satisfied criterion A, those who had a congenital colour sense anomaly were excluded. Overall, the 90th percentile (95th percentile) CCI values for criteria A and B in the worse eye were 1.70 (1.95) and 1.59 (1.73), respectively. In subjects satisfying criterion B, the area under the receiver operating characteristic curve was 0.951 (95% confidence interval, 0.931-0.971). The CCI discrimination values of 1.52 or 1.63 showed 90.3% sensitivity and 90% specificity, or 71.5% sensitivity and 95% specificity, respectively, for discriminating acquired colour vision impairment (ACVI). We provided the 90th and 95th percentiles in a young to middle-aged healthy population. The CCI is in good agreement with the diagnosis of ACVI. Our results could be helpful for using D-15DS for screening purposes.

Tractography-based classification in distinguishing patients with first-episode schizophrenia from healthy individuals.

PubMed

Deng, Yi; Hung, Karen S Y; Lui, Simon S Y; Chui, William W H; Lee, Joe C W; Wang, Yi; Li, Zhi; Mak, Henry K F; Sham, Pak C; Chan, Raymond C K; Cheung, Eric F C

2018-06-20

Schizophrenia has been characterized as a neurodevelopmental disorder of brain disconnectivity. However, whether disrupted integrity of white matter tracts in schizophrenia can potentially serve as individual discriminative biomarkers remains unclear. A random forest algorithm was applied to tractography-based diffusion properties obtained from a cohort of 65 patients with first-episode schizophrenia (FES) and 60 healthy individuals to investigate the machine-learning discriminative power of white matter disconnectivity. Recursive feature elimination was used to select the ultimate white matter features in the classification. Relationships between algorithm-predicted probabilities and clinical characteristics were also examined in the FES group. The classifier was trained by 80% of the sample. Patients were distinguished from healthy individuals with an overall accuracy of 71.0% (95% confident interval: 61.1%, 79.6%), a sensitivity of 67.3%, a specificity of 75.0%, and the area under receiver operating characteristic curve (AUC) was 79.3% (χ2 p < 0.001). In validation using the held-up 20% of the sample, patients were distinguished from healthy individuals with an overall accuracy of 76.0% (95% confident interval: 54.9%, 90.6%), a sensitivity of 76.9%, a specificity of 75.0%, and an AUC of 73.1% (χ2 p = 0.012). Diffusion properties of inter-hemispheric fibres, the cerebello-thalamo-cortical circuits and the long association fibres were identified to be the most discriminative in the classification. Higher predicted probability scores were found in younger patients. Our findings suggest that the widespread connectivity disruption observed in FES patients, especially in younger patients, might be considered potential individual discriminating biomarkers. Copyright © 2018. Published by Elsevier Inc.

Matching: Its Acquisition and Generalization

ERIC Educational Resources Information Center

Crowley, Michael A.; Donahoe, John W.

2004-01-01

Choice typically is studied by exposing organisms to concurrent variable-interval schedules in which not only responses controlled by stimuli on the key are acquired but also switching responses and likely other operants as well. In the present research, discriminated key-pecking responses in pigeons were first acquired using a multiple schedule…

Near-Term Fetuses Process Temporal Features of Speech

ERIC Educational Resources Information Center

Granier-Deferre, Carolyn; Ribeiro, Aurelie; Jacquet, Anne-Yvonne; Bassereau, Sophie

2011-01-01

The perception of speech and music requires processing of variations in spectra and amplitude over different time intervals. Near-term fetuses can discriminate acoustic features, such as frequencies and spectra, but whether they can process complex auditory streams, such as speech sequences and more specifically their temporal variations, fast or…

Auditory Memory for Timbre

ERIC Educational Resources Information Center

McKeown, Denis; Wellsted, David

2009-01-01

Psychophysical studies are reported examining how the context of recent auditory stimulation may modulate the processing of new sounds. The question posed is how recent tone stimulation may affect ongoing performance in a discrimination task. In the task, two complex sounds occurred in successive intervals. A single target component of one complex…

Illumination discrimination in the absence of a fixed surface-reflectance layout

PubMed Central

Radonjić, Ana; Ding, Xiaomao; Krieger, Avery; Aston, Stacey; Hurlbert, Anya C.; Brainard, David H.

2018-01-01

Previous studies have shown that humans can discriminate spectral changes in illumination and that this sensitivity depends both on the chromatic direction of the illumination change and on the ensemble of surfaces in the scene. These studies, however, always used stimulus scenes with a fixed surface-reflectance layout. Here we compared illumination discrimination for scenes in which the surface reflectance layout remains fixed (fixed-surfaces condition) to those in which surface reflectances were shuffled randomly across scenes, but with the mean scene reflectance held approximately constant (shuffled-surfaces condition). Illumination discrimination thresholds in the fixed-surfaces condition were commensurate with previous reports. Thresholds in the shuffled-surfaces condition, however, were considerably elevated. Nonetheless, performance in the shuffled-surfaces condition exceeded that attainable through random guessing. Analysis of eye fixations revealed that in the fixed-surfaces condition, low illumination discrimination thresholds (across observers) were predicted by low overall fixation spread and high consistency of fixation location and fixated surface reflectances across trial intervals. Performance in the shuffled-surfaces condition was not systematically related to any of the eye-fixation characteristics we examined for that condition, but was correlated with performance in the fixed-surfaces condition. PMID:29904786

Toward earlier detection of choroidal neovascularization secondary to age-related macular degeneration: multicenter evaluation of a preferential hyperacuity perimeter designed as a home device.

PubMed

Loewenstein, Anat; Ferencz, Joseph R; Lang, Yaron; Yeshurun, Itamar; Pollack, Ayala; Siegal, Ruth; Lifshitz, Tova; Karp, Joseph; Roth, Daniel; Bronner, Guri; Brown, Justin; Mansour, Sam; Friedman, Scott; Michels, Mark; Johnston, Richards; Rapp, Moshe; Havilio, Moshe; Rafaeli, Omer; Manor, Yair

2010-01-01

The primary purpose of this study was to evaluate the ability of a home device preferential hyperacuity perimeter to discriminate between patients with choroidal neovascularization (CNV) and intermediate age-related macular degeneration (AMD), and the secondary purpose was to investigate the dependence of sensitivity on lesion characteristics. All participants were tested with the home device in an unsupervised mode. The first part of this work was retrospective using tests performed by patients with intermediate AMD and newly diagnosed CNV. In the second part, the classifier was prospectively challenged with tests performed by patients with intermediate AMD and newly diagnosed CNV. The dependence of sensitivity on lesion characteristics was estimated with tests performed by patients with CNV of both parts. In 66 eyes with CNV and 65 eyes with intermediate AMD, both sensitivity and specificity were 0.85. In the retrospective part (34 CNV and 43 intermediate AMD), sensitivity and specificity were 0.85 +/- 0.12 (95% confidence interval) and 0.84 +/- 0.11 (95% confidence interval), respectively. In the prospective part (32 CNV and 22 intermediate AMD), sensitivity and specificity were 0.84 +/- 0.13 (95% confidence interval) and 0.86 +/- 0.14 (95% confidence interval), respectively. Chi-square analysis showed no dependence of sensitivity on type (P = 0.44), location (P = 0.243), or size (P = 0.73) of the CNV lesions. A home device preferential hyperacuity perimeter has good sensitivity and specificity in discriminating between patients with newly diagnosed CNV and intermediate AMD. Sensitivity is not dependent on lesion characteristics.

Logical metonymy resolution in a words-as-cues framework: evidence from self-paced reading and probe recognition.

PubMed

Zarcone, Alessandra; Padó, Sebastian; Lenci, Alessandro

2014-06-01

Logical metonymy resolution (begin a book → begin reading a book or begin writing a book) has traditionally been explained either through complex lexical entries (qualia structures) or through the integration of the implicit event via post-lexical access to world knowledge. We propose that recent work within the words-as-cues paradigm can provide a more dynamic model of logical metonymy, accounting for early and dynamic integration of complex event information depending on previous contextual cues (agent and patient). We first present a self-paced reading experiment on German subordinate sentences, where metonymic sentences and their paraphrased version differ only in the presence or absence of the clause-final target verb (Der Konditor begann die Glasur → Der Konditor begann, die Glasur aufzutragen/The baker began the icing → The baker began spreading the icing). Longer reading times at the target verb position in a high-typicality condition (baker + icing → spread ) compared to a low-typicality (but still plausible) condition (child + icing → spread) suggest that we make use of knowledge activated by lexical cues to build expectations about events. The early and dynamic integration of event knowledge in metonymy interpretation is bolstered by further evidence from a second experiment using the probe recognition paradigm. Presenting covert events as probes following a high-typicality or a low-typicality metonymic sentence (Der Konditor begann die Glasur → AUFTRAGEN/The baker began the icing → SPREAD), we obtain an analogous effect of typicality at 100 ms interstimulus interval. © 2014 Cognitive Science Society, Inc.

Semantic processing of unattended parafoveal words.

PubMed

Di Pace, E; Longoni, A M; Zoccolotti, P

1991-08-01

The influence that a context word presented either foveally or parafoveally, may exert on the processing of a subsequent target word was studied in a semantic decision task. Fourteen subjects participated in the experiment. They were presented with word-nonword pairs (prime). One member of the pair (which the subjects had to attend to) appeared centrally, the other parafoveally. The prime was followed by a target at two inter-stimulus intervals (ISI; 200 and 2000 msec). The word stimulus of the pair could be semantically related or unrelated to the target. The subjects' task was to classify the target as animal or not animal by pressing one of two buttons as quickly as possible. When the target word was semantically associated with the foveal (attended) word the reaction times were faster for both ISIs; when it was associated with the parafoveal (unattended) word in the prime pair, there were facilitatory effects only in the short ISI condition. A second experiment was run in order to evaluate the possibility that the obtained results were due to identification of the parafoveal stimulus. The same prime-target pairs of experiment 1 (without the target stimuli) were used. The prime-target pairs were presented to fourteen subjects who were requested to name the foveal (attended) stimulus and subsequently, if possible, the parafoveal (unattended) one. Even in this condition, percentage of identification of the unattended word was only 15%, suggesting that previous findings were not due to identification of unattended stimuli. Results are discussed in relation to Posner and Snyder's (1975) dual coding theory.

Self-face Captures, Holds, and Biases Attention.

PubMed

Wójcik, Michał J; Nowicka, Maria M; Kotlewska, Ilona; Nowicka, Anna

2017-01-01

The implicit self-recognition process may take place already in the pre-attentive stages of perception. After a silent stimulus has captured attention, it is passed on to the attentive stage where it can affect decision making and responding. Numerous studies show that the presence of self-referential information affects almost every cognitive level. These effects may share a common and fundamental basis in an attentional mechanism, conceptualized as attentional bias: the exaggerated deployment of attentional resources to a salient stimulus. A gold standard in attentional bias research is the dot-probe paradigm. In this task, a prominent stimulus (cue) and a neutral stimulus are presented in different spatial locations, followed by the presentation of a target. In the current study we aimed at investigating whether the self-face captures, holds and biases attention when presented as a task-irrelevant stimulus. In two dot-probe experiments coupled with the event-related potential (ERP) technique we analyzed the following relevant ERPs components: N2pc and SPCN which reflect attentional shifts and the maintenance of attention, respectively. An inter-stimulus interval separating face-cues and probes (800 ms) was introduced only in the first experiment. In line with our predictions, in Experiment 1 the self-face elicited the N2pc and the SPCN component. In Experiment 2 in addition to N2pc, an attentional bias was observed. Our results indicate that unintentional self-face processing disables the top-down control setting to filter out distractors, thus leading to the engagement of attentional resources and visual short-term memory.

A behavioural investigation of human visual short term memory for colour.

PubMed

Nemes, V A; Parry, N R A; McKeefry, D J

2010-09-01

We examined visual short term memory (VSTM) for colour using a delayed-match-to-sample paradigm. In these experiments we measured the effects of increasing inter-stimulus interval (ISI), varying between 0 and 10 s, on the ability of five colour normal human observers to make colour matches between a reference and subsequently presented test stimuli. The coloured stimuli used were defined by different chromatic axes on the isoluminant plane of DKL colour space. In preliminary experiments we used a hue scaling procedure to identify a total of 12 colour stimuli which served as reference hues in the colour memory experiments: four stimuli were exemplars of red, green, blue and yellow colour appearance categories, four were located between these categories and a further four were located on the cardinal axes that isolated the activity of the cone-opponent mechanisms. Our results demonstrate that there is a reduction in the ability of observers to make accurate colour matches with increasing ISIs and that this reduced performance was similar for all colour stimuli. However, the shifts in hue that were measured between the reference and matched test stimuli were significantly greater for the cardinal stimuli compared to those measured for the stimuli defined by the hue scaling procedure. This deterioration in the retention of hue in VSTM for stimuli that isolate cone-opponent mechanisms may be a reflection of the reorganisation of colour processing that occurs in the cortex where colour appearance mechanisms become more prominent. © 2010 The Authors, Ophthalmic and Physiological Optics © 2010 The College of Optometrists.

Statistical parametric mapping of LORETA using high density EEG and individual MRI: application to mismatch negativities in schizophrenia.

PubMed

Park, Hae-Jeong; Kwon, Jun Soo; Youn, Tak; Pae, Ji Soo; Kim, Jae-Jin; Kim, Myung-Sun; Ha, Kyoo-Seob

2002-11-01

We describe a method for the statistical parametric mapping of low resolution electromagnetic tomography (LORETA) using high-density electroencephalography (EEG) and individual magnetic resonance images (MRI) to investigate the characteristics of the mismatch negativity (MMN) generators in schizophrenia. LORETA, using a realistic head model of the boundary element method derived from the individual anatomy, estimated the current density maps from the scalp topography of the 128-channel EEG. From the current density maps that covered the whole cortical gray matter (up to 20,000 points), volumetric current density images were reconstructed. Intensity normalization of the smoothed current density images was used to reduce the confounding effect of subject specific global activity. After transforming each image into a standard stereotaxic space, we carried out statistical parametric mapping of the normalized current density images. We applied this method to the source localization of MMN in schizophrenia. The MMN generators, produced by a deviant tone of 1,200 Hz (5% of 1,600 trials) under the standard tone of 1,000 Hz, 80 dB binaural stimuli with 300 msec of inter-stimulus interval, were measured in 14 right-handed schizophrenic subjects and 14 age-, gender-, and handedness-matched controls. We found that the schizophrenic group exhibited significant current density reductions of MMN in the left superior temporal gyrus and the left inferior parietal gyrus (P < 0. 0005). This study is the first voxel-by-voxel statistical mapping of current density using individual MRI and high-density EEG. Copyright 2002 Wiley-Liss, Inc.

Real-time cerebellar neuroprosthetic system based on a spiking neural network model of motor learning.

PubMed

Xu, Tao; Xiao, Na; Zhai, Xiaolong; Kwan Chan, Pak; Tin, Chung

2018-02-01

Damage to the brain, as a result of various medical conditions, impacts the everyday life of patients and there is still no complete cure to neurological disorders. Neuroprostheses that can functionally replace the damaged neural circuit have recently emerged as a possible solution to these problems. Here we describe the development of a real-time cerebellar neuroprosthetic system to substitute neural function in cerebellar circuitry for learning delay eyeblink conditioning (DEC). The system was empowered by a biologically realistic spiking neural network (SNN) model of the cerebellar neural circuit, which considers the neuronal population and anatomical connectivity of the network. The model simulated synaptic plasticity critical for learning DEC. This SNN model was carefully implemented on a field programmable gate array (FPGA) platform for real-time simulation. This hardware system was interfaced in in vivo experiments with anesthetized rats and it used neural spikes recorded online from the animal to learn and trigger conditioned eyeblink in the animal during training. This rat-FPGA hybrid system was able to process neuronal spikes in real-time with an embedded cerebellum model of ~10 000 neurons and reproduce learning of DEC with different inter-stimulus intervals. Our results validated that the system performance is physiologically relevant at both the neural (firing pattern) and behavioral (eyeblink pattern) levels. This integrated system provides the sufficient computation power for mimicking the cerebellar circuit in real-time. The system interacts with the biological system naturally at the spike level and can be generalized for including other neural components (neuron types and plasticity) and neural functions for potential neuroprosthetic applications.

Unconscious Processing of Facial Emotional Valence Relation: Behavioral Evidence of Integration between Subliminally Perceived Stimuli.

PubMed

Liu, Chengzhen; Sun, Zhiyi; Jou, Jerwen; Cui, Qian; Zhao, Guang; Qiu, Jiang; Tu, Shen

2016-01-01

Although a few studies have investigated the integration between some types of unconscious stimuli, no research has yet explored the integration between unconscious emotional stimuli. This study was designed to provide behavioral evidence for the integration between unconsciously perceived emotional faces (same or different valence relation) using a modified priming paradigm. In two experiments, participants were asked to decide whether two faces in the target, which followed two subliminally presented faces of same or different emotional expressions, were of the same or different emotional valence. The interstimulus interval (ISI) between the prime and the target was manipulated (0, 53, 163 ms). In Experiment 1, prime visibility was assessed post-experiment. In Experiment 2, it was assessed on each trial. Interestingly, in both experiments, unconsciously processed valence relation of the two faces in the prime generated a negative priming effect in the response to the supraliminally presented target, independent of the length of ISI. Further analyses suggested that the negative priming was probably caused by a motor response incongruent relation between the subliminally perceived prime and the supraliminally perceived target. The visual feature incongruent relation across the prime and target was not found to play a role in the negative priming. Because the negative priming was found at short ISI, an attention mechanism as well as a motor inhibition mechanism were proposed in the generation of the negative priming effect. Overall, this study indicated that the subliminal valence relation was processed, and that integration between different unconsciously perceived stimuli could occur.

Impairment of sensory-motor plasticity in mild Alzheimer's disease.

PubMed

Terranova, Carmen; Carmen, Terranova; SantAngelo, Antonino; Antonino, Sant'Angelo; Morgante, Francesca; Francesca, Morgante; Rizzo, Vincenzo; Vincenzo, Rizzo; Allegra, Roberta; Roberta, Allegra; Arena, Maria Grazia; Grazia, Arena Maria; Ricciardi, Lucia; Lucia, Ricciardi; Ghilardi, Marie Felice; Felice, Ghilardi Maria; Girlanda, Paolo; Paolo, Girlanda; Quartarone, Angelo; Angelo, Quartarone

2013-01-01

Primary motor cortex (M1) is relatively spared in the early stages of Alzheimer's disease (AD). Aim of the present study was to investigate whether abnormal M1 synaptic plasticity is present at an early stage of AD. We employed an electrophysiological protocol, named rapid paired associative stimulation (rPAS), involving repetitive transcranial magnetic stimulation (rTMS) paired with electrical stimulation of the contralateral median nerve, that modifies corticospinal excitability and short latency afferent inhibition (SAI). We studied 10 patients with a diagnosis of probable mild AD according to the Mini Mental State Examination score (minimum 21) and 14 age-matched control subjects. Motor evoked potentials (MEP) amplitudes and short-afferent inhibition (SAI) were measured at baseline before and for up to 60 min after 5Hz-rPAS in abductor pollicis brevis (APB). rPAS consisted of 600 pairs of transcranial magnetic stimuli, at a rate of 5 Hz for 2 min, coupled with electrical median nerve stimulation preceding TMS over the contralateral M1 at an inter-stimulus interval of 25 ms. Baseline SAI was significantly reduced in AD patients. In the control subjects rPAS induced a significant increase in MEP amplitudes and a decrease of SAI in the APB muscle persistently for up to 1 h. Conversely 5Hz-rPAS did not induce any significant changes in MEP amplitudes and SAI in mild AD patients. Sensory-motor plasticity is impaired in the motor cortex of AD at an early stage of the disease. Copyright © 2013 Elsevier Inc. All rights reserved.

The impulse response of S-cone pathways in detection of increments and decrements

PubMed Central

Shinomori, Keizo; Werner, John S.

2008-01-01

Impulse response functions (IRFs) were obtained from two-pulse detection thresholds using isoluminant stimuli that produced increments or decrements in S-cone excitation. The pulses were chromatically modulated at constant luminance (based on 18 Hz heterochromatic flicker photometry). Chromatic stimuli were presented as a Gaussian patch (±1 SD = 2.3°) in one of four quadrants around a central fixation cross on a CRT screen. Each of the two pulses (6.67 ms) was separated by an inter-stimulus interval (ISI) from 20 to 360 ms. Chromaticity of the pulses was changed from the equal-energy white of the background to a bluish or yellowish color along individually determined tritan lines (based on color matching under strong S-cone adaptation from a 420 nm background superimposed in Maxwellian view). Chromatic detection thresholds were determined by a four-alternative forced-choice method with staircases for each ISI interleaved in each session. Measurements were repeated in at least four sessions for each observer. IRFs were calculated by varying four parameters of an exponentially-damped sinewave. Both S-cone increment and decrement IRFs are characterized by a single excitatory phase and a much longer time course compared with IRFs derived for luminance modulation using the same apparatus and observers. S-cone increment IRFs are faster than S-cone decrement IRFs; the time to peak amplitude of S-cone increment and decrement IRFs is 50–70 and 100–120 ms, respectively. These results were used to derive the temporal contrast sensitivity for human observers of putative ON- and OFF-channels carrying signals from S-cones. PMID:18321402

A Gap in Time: Extending our Knowledge of Temporal Processing Deficits in the HIV-1 Transgenic Rat.

PubMed

McLaurin, Kristen A; Moran, Landhing M; Li, Hailong; Booze, Rosemarie M; Mactutus, Charles F

2017-03-01

Approximately 50 % of HIV-1 seropositive individuals develop HIV-1 associated neurocognitive disorders (HAND), which commonly include alterations in executive functions, such as inhibition, set shifting, and complex problem solving. Executive function deficits in HIV-1 are fairly well characterized, however, relatively few studies have explored the elemental dimensions of neurocognitive impairment in HIV-1. Deficits in temporal processing, caused by HIV-1, may underlie the symptoms of impairment in higher level cognitive processes. Translational measures of temporal processing, including cross-modal prepulse inhibition (PPI), gap-prepulse inhibition (gap-PPI), and gap threshold detection, were studied in mature (ovariectomized) female HIV-1 transgenic (Tg) rats, which express 7 of the 9 HIV-1 genes constitutively throughout development. Cross-modal PPI revealed a relative insensitivity to the manipulation of interstimulus interval (ISI) in HIV-1 Tg animals in comparison to control animals, extending previously reported temporal processing deficits in HIV-1 Tg rats to a more advanced age, suggesting the permanence of temporal processing deficits. In gap-PPI, HIV-1 Tg animals exhibited a relative insensitivity to the manipulation of ISI in comparison to control animals. In gap-threshold detection, HIV-1 Tg animals displayed a profound differential sensitivity to the manipulation of gap duration. Presence of the HIV-1 transgene was diagnosed with 91.1 % accuracy using gap threshold detection measures. Understanding the generality and permanence of temporal processing deficits in the HIV-1 Tg rat is vital to modeling neurocognitive deficits observed in HAND and provides a key target for the development of a diagnostic screening tool.

The effects of combined exposure to the pyrethroids deltamethrin and S-bioallethrin on hippocampal inhibition and skeletal muscle hyperexcitability in rats

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

Ray, David E.; Burr, Steven A.; Lister, Timothy

2006-10-15

The default assumption that different pyrethroid insecticides, sharing a common mode of action, will show additivity of toxicity has not always been supported by in vitro measures, some of which have indicated antagonism. Our intention was to see whether the antagonism between pyrethroids of different classes seen in vitro could be reproduced in vivo. We therefore investigated the effects of single and combined exposures to two commonly used pyrethroids, deltamethrin (type II) and S-bioallethrin (type I) given intravenously to anaesthetised rats. We used two quantitative measures that are responsive to pyrethroids: the duration of prolongation of hippocampal dentate granule cellmore » inhibition and the amplitude of the abnormal electromyogram discharge. At equi-toxic doses, S-bioallethrin extended the inter-stimulus interval evoking 50% inhibition in the hippocampus by 30 {+-} 2.2 ms, and deltamethrin extended it by 199 {+-} 21 ms. Combined administration of the same doses of deltamethrin and S-bioallethrin extended hippocampal inhibition by 164 {+-} 14 ms, which did not differ significantly from the effect of deltamethrin alone. S-bioallethrin was without any effect on the electromyogram, and produced no significant change in the amplitude of the abnormal muscle discharges evoked by deltamethrin. The increase in arterial blood pressure evoked by the combination was significantly less than that evoked by either pyrethroid alone (p < 0.001). In summary, although our electrophysiological indices provide no support for functional antagonism between these two pyrethroids, they also fail to indicate any summation of effect.« less

Electrophysiological evidence for attenuated auditory recovery cycles in children with specific language impairment

PubMed Central

Stevens, Courtney; Paulsen, David; Yasen, Alia; Mitsunaga, Leila; Neville, Helen

2012-01-01

Previous research indicates that at least some children with specific language impairment (SLI) show a reduced neural response when non-linguistic tones were presented at rapid rates. However, this past research has examined older children, and it is unclear whether such deficits emerge earlier in development. It is also unclear whether atypical refractory effects differ for linguistic versus non-linguistic stimuli or can be explained by deficits in selective auditory attention reported among children with SLI. In the present study, auditory refractory periods were compared in a group of 24 young children with SLI (age 3–8 years) and 24 matched control children. Event-related brain potentials (ERPs) were recorded and compared to 100 ms linguistic and non-linguistic probe stimuli presented at inter-stimulus intervals (ISIs) of 200, 500, or 1000 ms. These probes were superimposed on story narratives when attended and ignored, permitting an experimental manipulation of selective attention within the same paradigm. Across participants, clear refractory effects were observed with this paradigm, evidenced as a reduced amplitude response from 100 to 200 ms at shorter ISIs. Children with SLI showed reduced amplitude ERPs relative to the typically-developing group at only the shortest, 200 ms, ISI and this difference was over the left-hemisphere for linguistic probes and over the right-hemisphere for non-linguistic probes. None of these effects was influenced by the direction of selective attention. Taken together, these findings suggest that deficits in the neural representation of rapidly presented auditory stimuli may be one risk factor for atypical language development. PMID:22265331

Upper-limb muscle responses to epidural, subdural and intraspinal stimulation of the cervical spinal cord

NASA Astrophysics Data System (ADS)

Sharpe, Abigail N.; Jackson, Andrew

2014-02-01

Objective. Electrical stimulation of the spinal cord has potential applications following spinal cord injury for reanimating paralysed limbs and promoting neuroplastic changes that may facilitate motor rehabilitation. Here we systematically compare the efficacy, selectivity and frequency-dependence of different stimulation methods in the cervical enlargement of anaesthetized monkeys. Approach. Stimulating electrodes were positioned at multiple epidural and subdural sites on both dorsal and ventral surfaces, as well as at different depths within the spinal cord. Motor responses were recorded from arm, forearm and hand muscles. Main results. Stimulation efficacy increased from dorsal to ventral stimulation sites, with the exception of ventral epidural electrodes which had the highest recruitment thresholds. Compared to epidural and intraspinal methods, responses to subdural stimulation were more selective but also more similar between adjacent sites. Trains of stimuli delivered to ventral sites elicited consistent responses at all frequencies whereas from dorsal sites we observed a mixture of short-latency facilitation and long-latency suppression. Finally, paired stimuli delivered to dorsal surface and intraspinal sites exhibited symmetric facilitatory interactions at interstimulus intervals between 2-5 ms whereas on the ventral side interactions tended to be suppressive for near-simultaneous stimuli. Significance. We interpret these results in the context of differential activation of afferent and efferent roots and intraspinal circuit elements. In particular, we propose that distinct direct and indirect actions of spinal cord stimulation on motoneurons may be advantageous for different applications, and this should be taken into consideration when designing neuroprostheses for upper-limb function.

Relationships between skin temperature and temporal summation of heat and cold pain.

PubMed

Mauderli, Andre P; Vierck, Charles J; Cannon, Richard L; Rodrigues, Anthony; Shen, Chiayi

2003-07-01

Temporal summation of heat pain during repetitive stimulation is dependent on C nociceptor activation of central N-methyl-d-aspartate (NMDA) receptor mechanisms. Moderate temporal summation is produced by sequential triangular ramps of stimulation that control skin temperature between heat pulses but do not elicit distinct first and second pain sensations. Dramatic summation of second pain is produced by repeated contact of the skin with a preheated thermode, but skin temperature between taps is not controlled by this procedure. Therefore relationships between recordings of skin temperature and psychophysical ratings of heat pain were evaluated during series of repeated skin contacts. Surface and subcutaneous recordings of skin temperatures revealed efficient thermoregulatory compensation for heat stimulation at interstimulus intervals (ISIs) ranging from 2 to 8 s. Temporal summation of heat pain was strongly influenced by the ISIs and cannot be explained by small increases in skin temperature between taps or by heat storage throughout a stimulus series. Repetitive brief contact with a precooled thermode was utilized to evaluate whether temporal summation of cold pain occurs, and if so, whether it is influenced by skin temperature. Surface and subcutaneous recordings of skin temperature revealed a sluggish thermoregulatory compensation for repetitive cold stimulation. In contrast to heat stimulation, skin temperature did not recover between cold stimuli throughout ISIs of 3-8 s. Psychophysically, repetitive cold stimulation produced an aching pain sensation that progressed gradually and radiated beyond the site of stimulation. The magnitude of aching pain was well related to skin temperature and thus appeared to be established primarily by peripheral factors.

Using a Sequence of Earcons to Monitor Multiple Simulated Patients.

PubMed

Hickling, Anna; Brecknell, Birgit; Loeb, Robert G; Sanderson, Penelope

2017-03-01

The aim of this study was to determine whether a sequence of earcons can effectively convey the status of multiple processes, such as the status of multiple patients in a clinical setting. Clinicians often monitor multiple patients. An auditory display that intermittently conveys the status of multiple patients may help. Nonclinician participants listened to sequences of 500-ms earcons that each represented the heart rate (HR) and oxygen saturation (SpO 2 ) levels of a different simulated patient. In each sequence, one, two, or three patients had an abnormal level of HR and/or SpO 2 . In Experiment 1, participants reported which of nine patients in a sequence were abnormal. In Experiment 2, participants identified the vital signs of one, two, or three abnormal patients in sequences of one, five, or nine patients, where the interstimulus interval (ISI) between earcons was 150 ms. Experiment 3 used the five-sequence condition of Experiment 2, but the ISI was either 150 ms or 800 ms. Participants reported which patient(s) were abnormal with median 95% accuracy. Identification accuracy for vital signs decreased as the number of abnormal patients increased from one to three, p < .001, but accuracy was unaffected by number of patients in a sequence. Overall, identification accuracy was significantly higher with an ISI of 800 ms (89%) compared with an ISI of 150 ms (83%), p < .001. A multiple-patient display can be created by cycling through earcons that represent individual patients. The principles underlying the multiple-patient display can be extended to other vital signs, designs, and domains.

Unconscious Processing of Facial Emotional Valence Relation: Behavioral Evidence of Integration between Subliminally Perceived Stimuli

PubMed Central

Jou, Jerwen; Cui, Qian; Zhao, Guang; Qiu, Jiang; Tu, Shen

2016-01-01

Although a few studies have investigated the integration between some types of unconscious stimuli, no research has yet explored the integration between unconscious emotional stimuli. This study was designed to provide behavioral evidence for the integration between unconsciously perceived emotional faces (same or different valence relation) using a modified priming paradigm. In two experiments, participants were asked to decide whether two faces in the target, which followed two subliminally presented faces of same or different emotional expressions, were of the same or different emotional valence. The interstimulus interval (ISI) between the prime and the target was manipulated (0, 53, 163 ms). In Experiment 1, prime visibility was assessed post-experiment. In Experiment 2, it was assessed on each trial. Interestingly, in both experiments, unconsciously processed valence relation of the two faces in the prime generated a negative priming effect in the response to the supraliminally presented target, independent of the length of ISI. Further analyses suggested that the negative priming was probably caused by a motor response incongruent relation between the subliminally perceived prime and the supraliminally perceived target. The visual feature incongruent relation across the prime and target was not found to play a role in the negative priming. Because the negative priming was found at short ISI, an attention mechanism as well as a motor inhibition mechanism were proposed in the generation of the negative priming effect. Overall, this study indicated that the subliminal valence relation was processed, and that integration between different unconsciously perceived stimuli could occur. PMID:27622600

Time frequency analysis of olfactory induced EEG-power change.

PubMed

Schriever, Valentin Alexander; Han, Pengfei; Weise, Stefanie; Hösel, Franziska; Pellegrino, Robert; Hummel, Thomas

2017-01-01

The objective of the present study was to investigate the usefulness of time-frequency analysis (TFA) of olfactory-induced EEG change with a low-cost, portable olfactometer in the clinical investigation of smell function. A total of 78 volunteers participated. The study was composed of three parts where olfactory stimuli were presented using a custom-built olfactometer. Part I was designed to optimize the stimulus as well as the recording conditions. In part II EEG-power changes after olfactory/trigeminal stimulation were compared between healthy participants and patients with olfactory impairment. In Part III the test-retest reliability of the method was evaluated in healthy subjects. Part I indicated that the most effective paradigm for stimulus presentation was cued stimulus, with an interstimulus interval of 18-20s at a stimulus duration of 1000ms with each stimulus quality presented 60 times in blocks of 20 stimuli each. In Part II we found that central processing of olfactory stimuli analyzed by TFA differed significantly between healthy controls and patients even when controlling for age. It was possible to reliably distinguish patients with olfactory impairment from healthy individuals at a high degree of accuracy (healthy controls vs anosmic patients: sensitivity 75%; specificity 89%). In addition we could show a good test-retest reliability of TFA of chemosensory induced EEG-power changes in Part III. Central processing of olfactory stimuli analyzed by TFA reliably distinguishes patients with olfactory impairment from healthy individuals at a high degree of accuracy. Importantly this can be achieved with a simple olfactometer.

Does the sight of physical threat induce a tactile processing bias? Modality-specific attentional facilitation induced by viewing threatening pictures.

PubMed

Van Damme, Stefaan; Gallace, Alberto; Spence, Charles; Crombez, Geert; Moseley, G Lorimer

2009-02-09

Threatening stimuli are thought to bias spatial attention toward the location from which the threat is presented. Although this effect is well-established in the visual domain, little is known regarding whether tactile attention is similarly affected by threatening pictures. We hypothesised that tactile attention might be more affected by cues implying physical threat to a person's bodily tissues than by cues implying general threat. In the present study, participants made temporal order judgments (TOJs) concerning which of a pair of tactile (or auditory) stimuli, one presented to either hand, at a range of inter-stimulus intervals, had been presented first. A picture (showing physical threat, general threat, or no threat) was presented in front of one or the other hand shortly before the tactile stimuli. The results revealed that tactile attention was biased toward the side on which the picture was presented, and that this effect was significantly larger for physical threat pictures than for general threat or neutral pictures. By contrast, the bias in auditory attention toward the side of the picture was significantly larger for general threat pictures than for physical threat pictures or neutral pictures. These findings therefore demonstrate a modality-specific effect of physically threatening cues on the processing of tactile stimuli, and of generally threatening cues on auditory information processing. These results demonstrate that the processing of tactile information from the body part closest to the threatening stimulus is prioritized over tactile information from elsewhere on the body.

The 3-Second Rule in Hereditary Pure Cerebellar Ataxia: A Synchronized Tapping Study

PubMed Central

Matsuda, Shunichi; Matsumoto, Hideyuki; Furubayashi, Toshiaki; Hanajima, Ritsuko; Tsuji, Shoji; Ugawa, Yoshikazu; Terao, Yasuo

2015-01-01

The ‘3-second rule’ has been proposed based on miscellaneous observations that a time period of around 3 seconds constitutes the fundamental unit of time related to the neuro-cognitive machinery in normal humans. The aim of paper was to investigate the temporal processing in patients with spinocerebellar ataxia type 6 (SCA6) and SCA31, pure cerebellar types of spinocerebellar degeneration, using a synchronized tapping task. Seventeen SCA patients (11 SCA6, 6 SCA31) and 17 normal age-matched volunteers participated. The task required subjects to tap a keyboard in synchrony with sequences of auditory stimuli presented at fixed interstimulus intervals (ISIs) between 200 and 4800 ms. In this task, the subjects required non-motor components to estimate the time of forthcoming tone in addition to motor components to tap. Normal subjects synchronized their taps to the presented tones at shorter ISIs, whereas as the ISI became longer, the normal subjects displayed greater latency between the tone and the tapping (transition zone). After the transition zone, normal subjects pressed the button delayed relative to the tone. On the other hand, SCA patients could not synchronize their tapping with the tone even at shorter ISIs, although they pressed the button delayed relative to the tone earlier than normal subjects did. The earliest time of delayed tapping appearance after the transition zone was 4800 ms in normal subjects but 1800 ms in SCA patients. The span of temporal integration in SCA patients is shortened compared to that in normal subjects. This could represent non-motor cerebellar dysfunction in SCA patients. PMID:25706752

Functional difference in short- and long-latency interhemispheric inhibitions from active to resting hemisphere during a unilateral muscle contraction.

PubMed

Uehara, Kazumasa; Morishita, Takuya; Kubota, Shinji; Hirano, Masato; Funase, Kozo

2014-01-01

The aim of the present study was to investigate whether there is a functional difference in short-latency (SIHI) and long-latency (LIHI) interhemispheric inhibition from the active to the resting primary motor cortex (M1) with paired-pulse transcranial magnetic stimulation during a unilateral muscle contraction. In nine healthy right-handed participants, IHI was tested from the dominant to the nondominant M1 and vice versa under resting conditions or during performance of a sustained unilateral muscle contraction with the right or left first dorsal interosseous muscle at 10% and 30% maximum voluntary contraction. To obtain measurements of SIHI and LIHI, a conditioning stimulus (CS) was applied over the M1 contralateral to the muscle contraction, followed by a test stimulus over the M1 ipsilateral to the muscle contraction at short (10 ms) and long (40 ms) interstimulus intervals. We used four CS intensities to investigate SIHI and LIHI from the active to the resting M1 systematically. The amount of IHI during the unilateral muscle contractions showed a significant difference between SIHI and LIHI, but the amount of IHI during the resting condition did not. In particular, SIHI during the muscle contractions, but not LIHI, significantly increased with increase in CS intensity compared with the resting condition. Laterality of IHI was not detected in any of the experimental conditions. The present study provides novel evidence that a functional difference between SIHI and LIHI from the active to the resting M1 exists during unilateral muscle contractions.

Peripheral vision and perceptual asymmetries in young and older martial arts athletes and nonathletes.

PubMed

Muiños, Mónica; Ballesteros, Soledad

2014-11-01

The present study investigated peripheral vision (PV) and perceptual asymmetries in young and older martial arts athletes (judo and karate athletes) and compared their performance with that of young and older nonathletes. Stimuli were dots presented at three different eccentricities along the horizontal, oblique, and vertical diameters and three interstimulus intervals. Experiment 1 showed that although the two athlete groups were faster in almost all conditions, karate athletes performed significantly better than nonathlete participants when stimuli were presented in the peripheral visual field. Experiment 2 showed that older participants who had practiced a martial art at a competitive level when they were young were significantly faster than sedentary older adults of the same age. The practiced sport (judo or karate) did not affect performance differentially, suggesting that it is the practice of martial arts that is the crucial factor, rather than the type of martial art. Importantly, older athletes lose their PV advantage, as compared with young athletes. Finally, we found that physical activity (young and older athletes) and age (young and older adults) did not alter the visual asymmetries that vary as a function of spatial location; all participants were faster for stimuli presented along the horizontal than for those presented along the vertical meridian and for those presented at the lower rather than at the upper locations within the vertical meridian. These results indicate that the practice of these martial arts is an effective way of counteracting the processing speed decline of visual stimuli appearing at any visual location and speed.

Neural Correlates of Subjective Awareness for Natural Scene Categorization of Color Photographs and Line-Drawings.

PubMed

Fu, Qiufang; Liu, Yong-Jin; Dienes, Zoltan; Wu, Jianhui; Chen, Wenfeng; Fu, Xiaolan

2017-01-01

It remains controversial whether visual awareness is correlated with early activation indicated by VAN (visual awareness negativity), as the recurrent process hypothesis theory proposes, or with later activation indicated by P3 or LP (late positive), as suggested by global workspace theories. To address this issue, a backward masking task was adopted, in which participants were first asked to categorize natural scenes of color photographs and line-drawings and then to rate the clarity of their visual experience on a Perceptual Awareness Scale (PAS). The interstimulus interval between the scene and the mask was manipulated. The behavioral results showed that categorization accuracy increased with PAS ratings for both color photographs and line-drawings, with no difference in accuracy between the two types of images for each rating, indicating that the experience rating reflected visibility. Importantly, the event-related potential (ERP) results revealed that for correct trials, the early posterior N1 and anterior P2 components changed with the PAS ratings for color photographs, but did not vary with the PAS ratings for line-drawings, indicating that the N1 and P2 do not always correlate with subjective visual awareness. Moreover, for both types of images, the anterior N2 and posterior VAN changed with the PAS ratings in a linear way, while the LP changed with the PAS ratings in a non-linear way, suggesting that these components relate to different types of subjective awareness. The results reconcile the apparently contradictory predictions of different theories and help to resolve the current debate on neural correlates of visual awareness.

Neural Correlates of Subjective Awareness for Natural Scene Categorization of Color Photographs and Line-Drawings

PubMed Central

Fu, Qiufang; Liu, Yong-Jin; Dienes, Zoltan; Wu, Jianhui; Chen, Wenfeng; Fu, Xiaolan

2017-01-01

It remains controversial whether visual awareness is correlated with early activation indicated by VAN (visual awareness negativity), as the recurrent process hypothesis theory proposes, or with later activation indicated by P3 or LP (late positive), as suggested by global workspace theories. To address this issue, a backward masking task was adopted, in which participants were first asked to categorize natural scenes of color photographs and line-drawings and then to rate the clarity of their visual experience on a Perceptual Awareness Scale (PAS). The interstimulus interval between the scene and the mask was manipulated. The behavioral results showed that categorization accuracy increased with PAS ratings for both color photographs and line-drawings, with no difference in accuracy between the two types of images for each rating, indicating that the experience rating reflected visibility. Importantly, the event-related potential (ERP) results revealed that for correct trials, the early posterior N1 and anterior P2 components changed with the PAS ratings for color photographs, but did not vary with the PAS ratings for line-drawings, indicating that the N1 and P2 do not always correlate with subjective visual awareness. Moreover, for both types of images, the anterior N2 and posterior VAN changed with the PAS ratings in a linear way, while the LP changed with the PAS ratings in a non-linear way, suggesting that these components relate to different types of subjective awareness. The results reconcile the apparently contradictory predictions of different theories and help to resolve the current debate on neural correlates of visual awareness. PMID:28261141

How Different Are Our Perceptions of Equal-Tempered and Microtonal Intervals? A Behavioural and EEG Survey.

PubMed

Bailes, Freya; Dean, Roger T; Broughton, Mary C

2015-01-01

For listeners familiar with Western twelve-tone equal-tempered (12-TET) music, a novel microtonal tuning system is expected to present additional processing challenges. We aimed to determine whether this was the case, focusing on the extent to which our perceptions can be considered bottom-up (psychoacoustic and primarily perceptual) and top-down (dependent on familiarity and cognitive processing). We elicited both overt response ratings, and covert event-related potentials (ERPs), so as to compare subjective impressions of sounds with the neurophysiological processing of the acoustic signal. We hypothesised that microtonal intervals are perceived differently from 12-TET intervals, and that the responses of musicians (n = 10) and non-musicians (n = 10) are distinct. Two-note chords were presented comprising 12-TET intervals (consonant and dissonant) or microtonal (quarter tone) intervals, and ERP, subjective roughness ratings, and liking ratings were recorded successively. Musical experience mediated the perception of differences between dissonant and microtone intervals, with non-musicians giving similar ratings for each, and musicians preferring dissonant over the less commonly used microtonal intervals, rating them as less rough. ERP response amplitude was greater for consonant intervals than other intervals. Musical experience interacted with interval type, suggesting that musical expertise facilitates the sensory and perceptual discrimination of microtonal intervals from 12-TET intervals, and an increased ability to categorize such intervals. Non-musicians appear to have perceived microtonal intervals as instances of neighbouring 12-TET intervals.

Perceived Discrimination and Incident Cardiovascular Events

PubMed Central

Everson-Rose, Susan A.; Lutsey, Pamela L.; Roetker, Nicholas S.; Lewis, Tené T.; Kershaw, Kiarri N.; Alonso, Alvaro; Diez Roux, Ana V.

2015-01-01

Perceived discrimination is positively related to cardiovascular disease (CVD) risk factors; its relationship with incident CVD is unknown. Using data from the Multi-Ethnic Study of Atherosclerosis, a population-based multiethnic cohort study of 6,508 adults aged 45–84 years who were initially free of clinical CVD, we examined lifetime discrimination (experiences of unfair treatment in 6 life domains) and everyday discrimination (frequency of day-to-day occurrences of perceived unfair treatment) in relation to incident CVD. During a median 10.1 years of follow-up (2000–2011), 604 incident events occurred. Persons reporting lifetime discrimination in ≥2 domains (versus none) had increased CVD risk, after adjustment for race/ethnicity and sociodemographic factors, behaviors, and traditional CVD risk factors (hazard ratio (HR) = 1.36, 95% confidence interval (CI): 1.09, 1.70) and after control for chronic stress and depressive symptoms (HR = 1.28, 95% CI: 1.01, 1.60). Reported discrimination in 1 domain was unrelated to CVD (HR = 1.05, 95% CI: 0.86, 1.30). There were no differences by race/ethnicity, age, or sex. In contrast, everyday discrimination interacted with sex (P = 0.03). Stratified models showed increased risk only among men (for each 1–standard deviation increase in score, adjusted HR = 1.14, 95% CI: 1.03, 1.27); controlling for chronic stress and depressive symptoms slightly reduced this association (HR = 1.11, 95% CI: 0.99, 1.25). This study suggests that perceived discrimination is adversely related to CVD risk in middle-aged and older adults. PMID:26085044

Figure-ground discrimination in the avian brain: the nucleus rotundus and its inhibitory complex.

PubMed

Acerbo, Martin J; Lazareva, Olga F; McInnerney, John; Leiker, Emily; Wasserman, Edward A; Poremba, Amy

2012-10-01

In primates, neurons sensitive to figure-ground status are located in striate cortex (area V1) and extrastriate cortex (area V2). Although much is known about the anatomical structure and connectivity of the avian visual pathway, the functional organization of the avian brain remains largely unexplored. To pinpoint the areas associated with figure-ground segregation in the avian brain, we used a radioactively labeled glucose analog to compare differences in glucose uptake after figure-ground, color, and shape discriminations. We also included a control group that received food on a variable-interval schedule, but was not required to learn a visual discrimination. Although the discrimination task depended on group assignment, the stimulus displays were identical for all three experimental groups, ensuring that all animals were exposed to the same visual input. Our analysis concentrated on the primary thalamic nucleus associated with visual processing, the nucleus rotundus (Rt), and two nuclei providing regulatory feedback, the pretectum (PT) and the nucleus subpretectalis/interstitio-pretecto-subpretectalis complex (SP/IPS). We found that figure-ground discrimination was associated with strong and nonlateralized activity of Rt and SP/IPS, whereas color discrimination produced strong and lateralized activation in Rt alone. Shape discrimination was associated with lower activity of Rt than in the control group. Taken together, our results suggest that figure-ground discrimination is associated with Rt and that SP/IPS may be a main source of inhibitory control. Thus, figure-ground segregation in the avian brain may occur earlier than in the primate brain. Copyright © 2012 Elsevier Ltd. All rights reserved.

Figure-ground discrimination in the avian brain: The nucleus rotundus and its inhibitory complex

PubMed Central

Acerbo, Martin J.; Lazareva, Olga F.; McInnerney, John; Leiker, Emily; Wasserman, Edward A.; Poremba, Amy

2012-01-01

In primates, neurons sensitive to figure-ground status are located in striate cortex (area V1) and extrastriate cortex (area V2). Although much is known about the anatomical structure and connectivity of the avian visual pathway, the functional organization of the avian brain remains largely unexplored. To pinpoint the areas associated with figure-ground segregation in the avian brain, we used a radioactively labeled glucose analog to compare differences in glucose uptake after figure-ground, color, and shape discriminations. We also included a control group that received food on a variable-interval schedule, but was not required to learn a visual discrimination. Although the discrimination task depended on group assignment, the stimulus displays were identical for all three experimental groups, ensuring that all animals were exposed to the same visual input. Our analysis concentrated on the primary thalamic nucleus associated with visual processing, the nucleus rotundus (Rt), and two nuclei providing regulatory feedback, the pretectum (PT) and the nucleus subpretectalis/interstitio-pretecto-subpretectalis complex (SP/IPS). We found that figure-ground discrimination was associated with strong and nonlateralized activity of Rt and SP/IPS, whereas color discrimination produced strong and lateralized activation in Rt alone. Shape discrimination was associated with lower activity of Rt than in the control group. Taken together, our results suggest that figure-ground discrimination is associated with Rt and that SP/IPS may be a main source of inhibitory control. Thus, figure-ground segregation in the avian brain may occur earlier than in the primate brain. PMID:22917681

Association between Perceived Discrimination in Healthcare Settings and HIV Medication Adherence: Mediating Psychosocial Mechanisms.

PubMed

Turan, Bulent; Rogers, Anna Joy; Rice, Whitney S; Atkins, Ghislaine C; Cohen, Mardge H; Wilson, Tracey E; Adimora, Adaora A; Merenstein, Daniel; Adedimeji, Adebola; Wentz, Eryka L; Ofotokun, Igho; Metsch, Lisa; Tien, Phyllis C; Johnson, Mallory O; Turan, Janet M; Weiser, Sheri D

2017-12-01

There is insufficient research on the impact of perceived discrimination in healthcare settings on adherence to antiretroviral therapy (ART), particularly among women living with HIV, and even less is known about psychosocial mechanisms that may mediate this association. Cross-sectional analyses were conducted in a sample of 1356 diverse women living with HIV enrolled in the Women's Interagency HIV Study (WIHS), a multi-center cohort study. Indirect effects analysis with bootstrapping was used to examine the potential mediating roles of internalized stigma and depressive symptoms in the association between perceived discrimination in healthcare settings and ART adherence. Perceived discrimination in healthcare settings was negatively associated with optimal (95% or better) ART adherence (adjusted odds ratio (AOR) = 0.81, p = 0.02, 95% confidence interval (CI) [0.68, 0.97]). Furthermore, internalization of stigma and depressive symptoms mediated the perceived discrimination-adherence association: Serial mediation analyses revealed a significant indirect effect of perceived discrimination in healthcare settings on ART adherence, first through internalized HIV stigma, and then through depressive symptoms (B = - 0.08, SE = 0.02, 95% CI [- 0.12, - 0.04]). Perceiving discrimination in healthcare settings may contribute to internalization of HIV-related stigma, which in turn may lead to depressive symptoms, with downstream adverse effects on ART adherence among women. These findings can guide the design of interventions to reduce discrimination in healthcare settings, as well as interventions targeting psychosocial mechanisms that may impact the ability of women living with HIV to adhere to ART regimens.

Vocal Accuracy and Neural Plasticity Following Micromelody-Discrimination Training

PubMed Central

Zarate, Jean Mary; Delhommeau, Karine; Wood, Sean; Zatorre, Robert J.

2010-01-01

Background Recent behavioral studies report correlational evidence to suggest that non-musicians with good pitch discrimination sing more accurately than those with poorer auditory skills. However, other studies have reported a dissociation between perceptual and vocal production skills. In order to elucidate the relationship between auditory discrimination skills and vocal accuracy, we administered an auditory-discrimination training paradigm to a group of non-musicians to determine whether training-enhanced auditory discrimination would specifically result in improved vocal accuracy. Methodology/Principal Findings We utilized micromelodies (i.e., melodies with seven different interval scales, each smaller than a semitone) as the main stimuli for auditory discrimination training and testing, and we used single-note and melodic singing tasks to assess vocal accuracy in two groups of non-musicians (experimental and control). To determine if any training-induced improvements in vocal accuracy would be accompanied by related modulations in cortical activity during singing, the experimental group of non-musicians also performed the singing tasks while undergoing functional magnetic resonance imaging (fMRI). Following training, the experimental group exhibited significant enhancements in micromelody discrimination compared to controls. However, we did not observe a correlated improvement in vocal accuracy during single-note or melodic singing, nor did we detect any training-induced changes in activity within brain regions associated with singing. Conclusions/Significance Given the observations from our auditory training regimen, we therefore conclude that perceptual discrimination training alone is not sufficient to improve vocal accuracy in non-musicians, supporting the suggested dissociation between auditory perception and vocal production. PMID:20567521

The role of critical ethnic awareness and social support in the discrimination-depression relationship among Asian Americans: path analysis.

PubMed

Kim, Isok

2014-01-01

This study used a path analytic technique to examine associations among critical ethnic awareness, racial discrimination, social support, and depressive symptoms. Using a convenience sample from online survey of Asian American adults (N = 405), the study tested 2 main hypotheses: First, based on the empowerment theory, critical ethnic awareness would be positively associated with racial discrimination experience; and second, based on the social support deterioration model, social support would partially mediate the relationship between racial discrimination and depressive symptoms. The result of the path analysis model showed that the proposed path model was a good fit based on global fit indices, χ²(2) = 4.70, p = .10; root mean square error of approximation = 0.06; comparative fit index = 0.97; Tucker-Lewis index = 0.92; and standardized root mean square residual = 0.03. The examinations of study hypotheses demonstrated that critical ethnic awareness was directly associated (b = .11, p < .05) with the racial discrimination experience, whereas social support had a significant indirect effect (b = .48; bias-corrected 95% confidence interval [0.02, 1.26]) between the racial discrimination experience and depressive symptoms. The proposed path model illustrated that both critical ethnic awareness and social support are important mechanisms for explaining the relationship between racial discrimination and depressive symptoms among this sample of Asian Americans. This study highlights the usefulness of the critical ethnic awareness concept as a way to better understand how Asian Americans might perceive and recognize racial discrimination experiences in relation to its mental health consequences.

Racial/ethnic discrimination, posttraumatic stress symptoms, and alcohol problems in a longitudinal study of Hispanic/Latino college students.

PubMed

Cheng, Hsiu-Lan; Mallinckrodt, Brent

2015-01-01

Racial/ethnic discrimination has been identified as a risk factor in the development of posttraumatic stress disorder (PTSD) symptoms in persons of color (Carter, 2007). Many persons, regardless of race/ethnicity, with PTSD symptoms resulting from combat, violent crimes, sexual assault, or natural disasters use alcohol in an attempt to cope. This longitudinal study surveyed 203 Hispanic/Latino students twice at approximately a 1-year interval, and used a cross-lagged design to compare Time 1 links from alcohol use and experiences of discrimination with the same variables at Time 2, plus symptoms of PTSD. Each survey included the General Ethnic Discrimination scale and the Alcohol Use Disorders Identification Test. Only Time 2 packets contained the Posttraumatic Stress Disorder Checklist-Civilian. Cross-lagged analyses conducted by comparing nested structural equation models found that fixing the causal paths to zero from Time 1 experiences of discrimination to Time 2 alcohol problems and PTSD resulted in a significantly worse fit of the data. However, fixing the paths to zero from Time 1 maladaptive alcohol use to Time 2 PTSD and experiences of discrimination resulted in no significant difference in model fit. Thus, this pattern of findings is consistent with an inference that Hispanic/Latino college students who experience racial/ethnic discrimination are at risk for developing symptoms of posttraumatic stress and increased maladaptive alcohol use; conversely, maladaptive alcohol use does not appear to be a risk factor for later experiences of discrimination or PTSD symptoms. PsycINFO Database Record (c) 2015 APA, all rights reserved.

Gender discrimination, educational attainment, and illicit drug use among U.S. women.

PubMed

Carliner, Hannah; Sarvet, Aaron L; Gordon, Allegra R; Hasin, Deborah S

2017-03-01

While gender inequality has been a topic of concern for decades, little is known about the relationship between gender discrimination and illicit drug use. Further, whether this association varies by education level is unknown. Among 19,209 women participants in Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (2004-2005), we used logistic regression to test the association between gender discrimination (measured with four items from the Experiences of Discrimination instrument) and three outcomes: past-year illicit drug use, frequent drug use, and drug use disorders. We then tested whether associations differed by education level. Gender discrimination was reported by 9% of women and was associated with past-year drug use [adjusted odds ratio (aOR) = 2.67; 95% confidence interval (CI) 2.17-3.29], frequent drug use (aOR = 2.82; CI 1.99-4.00), and past-year drug use disorders (aOR = 3.15; CI 2.16-4.61). All specific domains of gender discrimination (on the job, in public, with institutions, being called a sexist name) were associated with all drug use outcomes. The association between gender discrimination and past-year drug use was stronger among women with less than a high school education (aOR = 6.33; CI 3.38-11.85) compared to those with more education (aOR = 2.45; CI 1.97-3.04; p interaction  < 0.01). Gender discrimination is consistently and strongly associated with illicit drug use and drug use disorders among U.S. women, with significantly higher odds for drug use among women with less than a high school education. Future research should examine whether explicitly addressing distress from discrimination could benefit women in drug treatment, especially among clients with lower educational attainment.

Experiences of Discrimination and HIV Risk Among Men Who Have Sex With Men in New York City.

PubMed

Reilly, Kathleen H; Neaigus, Alan; Jenness, Samuel M; Wendel, Travis; Marshall, David M; Hagan, Holly

2016-11-01

The extent of gay-related discrimination in New York City (NYC) and the demographic and behavioral factors correlated with experiences of gay-related discrimination are not well understood. The Centers for Disease Control and Prevention-sponsored National HIV Behavioral Surveillance System, a cross-sectional study, was conducted in NYC in 2011. Men who have sex with men were venue-sampled, interviewed, and offered HIV testing. Frequencies of types of gay-related discrimination experienced in the past 12 months were calculated. Associations between types of discrimination and demographic and HIV risk variables were examined through the estimation of prevalence ratios (PRs) and 95% confidence intervals (CIs). More than half (53.2%) of all study participants reported having experienced any gay-related discrimination in the past 12 months; 45.0% reported that they had been called names or insulted; 23.6% reported receiving poorer services than other people in restaurants, stores, other businesses, or agencies; 22.0% reported being treated unfairly at work or school; 15.1% reported being physically attacked or injured; and 6.7% reported being denied or given lower quality health care. HIV-positive status (adjusted PR [aPR] = 2.9; 95% CI = 1.5, 5.6) and drug use in the past 12 months (aPR = 0.3; 95% CI = 0.1, 0.7) were independently associated with reports of having been denied or given lower quality health care. High rates of reported gay-related discrimination suggest that greater efforts are needed to reduce gay-related discrimination in affected communities. Future research is needed to better understand the extent of gay-related discrimination in NYC, particularly with regard to the relationship between HIV status and health care access. © The Author(s) 2015.

Perceived sex discrimination amplifies the effect of antagonism on cigarette smoking.

PubMed

Sutin, Angelina R; English, Devin; Evans, Michele K; Zonderman, Alan B

2014-06-01

Compared to men, the decline in smoking during the past few decades has been slower for women, and smoking-related morbidity and mortality has increased substantially. Identifying sex-specific risk factors will inform more targeted intervention/prevention efforts. The purpose of this research is to examine the interactive effect of psychological (trait antagonism) and social (perceived sex discrimination) factors on current cigarette smoking and whether these effects differ by sex. Participants in the Healthy Aging in Neighborhoods of Diversity across the Life Span study (HANDLS; N = 454) and participants in the Health and Retirement Study (HRS; N = 8,155) completed measures of antagonism, perceived sex discrimination, and reported whether they smoked currently. Logistic regressions were used to predict smoking from antagonism, discrimination, and their interaction. Antagonism was associated with an increased risk of smoking. For women, there was an interaction between antagonism and discrimination: among women who perceived sex discrimination, every standard deviation increase in antagonism was associated with a 2.5 increased risk of current smoking in HANDLS (odds ratio [OR] = 2.54, 95% confidence interval [CI] = 1.46-4.39) and an almost 1.5 increased risk in HRS (OR = 1.43, 95% CI = 1.18-1.73). This interaction was not significant for men in either sample. In 2 independent samples, perceived sex discrimination amplified the effect of antagonism on cigarette smoking for women but not men. A hostile disposition and a perceived hostile social environment have a synergistic effect on current cigarette smoking for women.

Double dissociation of pharmacologically induced deficits in visual recognition and visual discrimination learning

PubMed Central

Turchi, Janita; Buffalari, Deanne; Mishkin, Mortimer

2008-01-01

Monkeys trained in either one-trial recognition at 8- to 10-min delays or multi-trial discrimination habits with 24-h intertrial intervals received systemic cholinergic and dopaminergic antagonists, scopolamine and haloperidol, respectively, in separate sessions. Recognition memory was impaired markedly by scopolamine but not at all by haloperidol, whereas habit formation was impaired markedly by haloperidol but only minimally by scopolamine. These differential drug effects point to differences in synaptic modification induced by the two neuromodulators that parallel the contrasting properties of the two types of learning, namely, fast acquisition but weak retention of memories versus slow acquisition but durable retention of habits. PMID:18685146

Double dissociation of pharmacologically induced deficits in visual recognition and visual discrimination learning.

PubMed

Turchi, Janita; Buffalari, Deanne; Mishkin, Mortimer

2008-08-01

Monkeys trained in either one-trial recognition at 8- to 10-min delays or multi-trial discrimination habits with 24-h intertrial intervals received systemic cholinergic and dopaminergic antagonists, scopolamine and haloperidol, respectively, in separate sessions. Recognition memory was impaired markedly by scopolamine but not at all by haloperidol, whereas habit formation was impaired markedly by haloperidol but only minimally by scopolamine. These differential drug effects point to differences in synaptic modification induced by the two neuromodulators that parallel the contrasting properties of the two types of learning, namely, fast acquisition but weak retention of memories versus slow acquisition but durable retention of habits.

Lidar Luminance Quantizer

NASA Technical Reports Server (NTRS)

Quilligan, Gerard; DeMonthier, Jeffrey; Suarez, George

2011-01-01

This innovation addresses challenges in lidar imaging, particularly with the detection scheme and the shapes of the detected signals. Ideally, the echoed pulse widths should be extremely narrow to resolve fine detail at high event rates. However, narrow pulses require wideband detection circuitry with increased power dissipation to minimize thermal noise. Filtering is also required to shape each received signal into a form suitable for processing by a constant fraction discriminator (CFD) followed by a time-to-digital converter (TDC). As the intervals between the echoes decrease, the finite bandwidth of the shaping circuits blends the pulses into an analog signal (luminance) with multiple modes, reducing the ability of the CFD to discriminate individual events

Testing for time-based correlates of perceived gender discrimination.

PubMed

Blau, Gary; Tatum, Donna Surges; Ward-Cook, Kory; Dobria, Lidia; McCoy, Keith

2005-01-01

Using a sample of 201 medical technologists (MTs) over a five-year period, this study extends initial findings on perceived gender discrimination (PGD) by Blau and Tatum (2000) by applying organizational justice variables and internal-external locus of control as hypothesized correlates of PGD. Three types of organizational justice were measured: distributive, procedural, and interactional. General relationships found include locus of control being related to PGD such that internals perceived lower PGD. Also, distributive, procedural, and interactional justice were negatively related to PGD. However, increasing the time interval between these correlates weakened their relationships. The relationship of interactional justice to PGD remained the most "resistant" to attenuation over time.

Discrimination and Psychological Distress: Gender Differences among Arab Americans.

PubMed

Assari, Shervin; Lankarani, Maryam Moghani

2017-01-01

Despite the existing knowledge on the association between discrimination and poor mental health, very few studies have explored gender differences in this association in Arab Americans. The current study aimed to investigate whether gender moderates the association between the experience of discrimination and psychological distress in a representative sample of Arab Americans in Michigan. Using data from the Detroit Arab American Study (DAAS), 2003, this study recruited Arab Americans (337 males, 385 females) living in Michigan, United States. The main independent variable was discrimination. The main outcome was psychological distress. Covariates included demographic factors (age), socioeconomic status (education, employment, and income), and immigration characteristics (nativity and years living in United States). Gender was the focal moderator. We used multivariable regression with and without discrimination × gender interaction term. In the pooled sample, discrimination was positively associated with psychological distress [ B  = 0.62, 95% confidence interval (CI) = 0.22-1.03, p  = 0.003]. We found a significant gender × discrimination interaction in the pooled sample ( B  = 0.79, 95% CI = 0.01-1.59, p  = 0.050), suggesting a stronger association in males than females. In our gender-specific model, higher discrimination was associated with higher psychological distress among male ( B  = 0.87, 95% CI = 0.33-1.42, p  = 0.002) but not female ( B  = 0.18, 95% CI = -0.43 to 0.78, p  = 0.567) Arab Americans. While discrimination is associated with poor mental health, a stronger link between discrimination and psychological symptoms may exist in male compared to female Arab Americans. While efforts should be made to universally reduce discrimination, screening for discrimination may be a more salient component of mental health care for male than female Arab Americans.

Influence of musical and psychoacoustical training on pitch discrimination.

PubMed

Micheyl, Christophe; Delhommeau, Karine; Perrot, Xavier; Oxenham, Andrew J

2006-09-01

This study compared the influence of musical and psychoacoustical training on auditory pitch discrimination abilities. In a first experiment, pitch discrimination thresholds for pure and complex tones were measured in 30 classical musicians and 30 non-musicians, none of whom had prior psychoacoustical training. The non-musicians' mean thresholds were more than six times larger than those of the classical musicians initially, and still about four times larger after 2h of training using an adaptive two-interval forced-choice procedure; this difference is two to three times larger than suggested by previous studies. The musicians' thresholds were close to those measured in earlier psychoacoustical studies using highly trained listeners, and showed little improvement with training; this suggests that classical musical training can lead to optimal or nearly optimal pitch discrimination performance. A second experiment was performed to determine how much additional training was required for the non-musicians to obtain thresholds as low as those of the classical musicians from experiment 1. Eight new non-musicians with no prior training practiced the frequency discrimination task for a total of 14 h. It took between 4 and 8h of training for their thresholds to become as small as those measured in the classical musicians from experiment 1. These findings supplement and qualify earlier data in the literature regarding the respective influence of musical and psychoacoustical training on pitch discrimination performance.

Delayed temporal discrimination in pigeons: A comparison of two procedures

PubMed Central

Chatlosh, Diane L.; Wasserman, Edward A.

1987-01-01

A within-subjects comparison was made of pigeons' performance on two temporal discrimination procedures that were signaled by differently colored keylight samples. During stimulus trials, a peck on the key displaying a slanted line was reinforced following short keylight samples, and a peck on the key displaying a horizontal line was reinforced following long keylight samples, regardless of the location of the stimuli on those two choice keys. During position trials, a peck on the left key was reinforced following short keylight samples and a peck on the right key was reinforced following long keylight samples, regardless of which line stimulus appeared on the correct key. Thus, on stimulus trials, the correct choice key could not be discriminated prior to the presentation of the test stimuli, whereas on position trials, the correct choice key could be discriminated during the presentation of the sample stimulus. During Phase 1, with a 0-s delay between sample and choice stimuli, discrimination learning was faster on position trials than on stimulus trials for all 4 birds. During Phase 2, 0-, 0.5-, and 1.0-s delays produced differential loss of stimulus control under the two tasks for 2 birds. Response patterns during the delay intervals provided some evidence for differential mediation of the two delayed discriminations. These between-task differences suggest that the same processes may not mediate performance in each. PMID:16812483

Sexual Orientation-Based Discrimination, Excessive Alcohol Use, and Substance Use Disorders Among Sexual Minority Adults

PubMed Central

Godette, Dionne; Huang, Boji; Ruan, W. June; Kerridge, Bradley T.

2017-01-01

Abstract Purpose: The purpose of this study was to examine relationships between sexual orientation-based discrimination and excessive alcohol use and substance use disorders and to identify how these relationships differ by sexual identity, sex, race, Hispanic origin, and education among sexual minorities. Methods: We used logistic regression to analyze associations between discrimination and substance use measures among 1351 gay/lesbian, bisexual, or unsure adults from a nationally representative survey. Differential effects by sexual identity, sex, race, Hispanic origin, and education were assessed using interaction models followed by stratified models. Results: Discrimination was associated with increased odds of the following: exceeding weekly drinking limits [adjusted odds ratio (aOR) = 1.52, 95% confidence interval (CI): 1.12–2.08] among bisexuals, any substance use disorder (aOR = 2.04, 95% CI: 1.41–2.95) and nicotine use disorder (aOR = 1.52, 95% CI: 1.08–2.14) among Hispanic sexual minorities, and exceeding weekly drinking limits (aOR = 1.56, 95% CI: 1.08–2.26) among those with a high school degree or less. Conclusion: Sexual orientation-based discrimination was associated with select substance use outcomes, especially among bisexuals, Hispanics, and less educated sexual minority adults, highlighting potential disparities associated with experiencing discrimination. PMID:28876167

Racial Discrimination, Psychological Distress, and Self-Rated Health Among US-Born and Foreign-Born Black Americans

PubMed Central

Kosheleva, Anna; Waterman, Pamela D.; Chen, Jarvis T.; Koenen, Karestan

2011-01-01

Objectives. We investigated associations among racial discrimination, psychological distress, and self-rated health among US-born and immigrant Black Americans. Methods. We conducted a cross-sectional analysis of a cohort of employed working-class Black Americans (193 US-born, 275 foreign-born). Results. Both US-born and foreign-born Black participants had high levels of exposure to poverty (51% and 57%, respectively) and racial discrimination (76% and 60%) and reported high levels of severe psychological distress (14% and 16% had a Kessler 6 [K6] score of 13 or greater); 17% and 7% reported fair or poor health. After controlling for relevant covariates, their risk parameters for racial discrimination (high vs no exposure) were 4.0 (95% confidence interval [CI] = 2.3, 5.6) and 3.3 (95% CI = 2.1, 4.5), respectively, for continuous K6 score; corresponding odds ratios for severe psychological distress were 6.9 (95% CI = 1.4, 35.7) and 6.8 (95% CI = 2.5, 18.3). No associations existed between racial discrimination and self-reported health, suggesting that an underlying propensity to report adversity does not account for our psychological distress findings. Conclusions. Our results attest to the salience of racial discrimination, nativity, and socioeconomic position in understanding the experiences and psychological health of Black Americans. PMID:21778504

Discriminated Timeout Avoidance in Pigeons: The Roles of Added Stimuli

ERIC Educational Resources Information Center

DeFulio, Anthony; Hackenberg, Timothy D.

2007-01-01

Two experiments examined pigeons' postponement of a signaled extinction period, or timeout (TO), from an ongoing schedule of response-dependent food delivery. A concurrent-operant procedure was used in which responses on one (food) key produced food according to a variable-interval schedule and responses on a second (postponement) key delayed the…

Late Maturation of Auditory Perceptual Learning

ERIC Educational Resources Information Center

Huyck, Julia Jones; Wright, Beverly A.

2011-01-01

Adults can improve their performance on many perceptual tasks with training, but when does the response to training become mature? To investigate this question, we trained 11-year-olds, 14-year-olds and adults on a basic auditory task (temporal-interval discrimination) using a multiple-session training regimen known to be effective for adults. The…

Effect of Age on Silent Gap Discrimination in Synthetic Speech Stimuli.

ERIC Educational Resources Information Center

Lister, Jennifer; Tarver, Kenton

2004-01-01

The difficulty that older listeners experience understanding conversational speech may be related to their limited ability to use information present in the silent intervals (i.e., temporal gaps) between dynamic speech sounds. When temporal gaps are present between nonspeech stimuli that are spectrally invariant (e.g., noise bands or sinusoids),…

The acquisition of observing.

PubMed Central

Dinsmoor, J A; Mueller, K L; Martin, L T; Bowe, C A

1982-01-01

Pigeons were exposed to stimuli correlated with the presence or absence of a variable-interval 60-second schedule of reinforcement only while they depressed a crossbar or "perch." In the first experiment, the stimuli were different tilts of a line displayed on the key. When the difference in brightness between the line and the background (salience) was maximal, seven of eight birds acquired the discrimination, but when the difference was reduced by 50%, only one succeeded. In the second experiment, wavelength of chamber illumination served as the relevant dimension. Neither experiment showed a large effect attributable to the magnitude of the difference (disparity) between the positive and the negative stimulus. Individual differences in time spent observing were positively correlated with level of discrimination in the presence of the stimuli. All birds produced the positive stimulus for a greater proportion of the available time than they did the negative stimulus. This may be the mechanism that provides selective reinforcement of observing. Finally, the formation of a discrimination was analyzed in terms of changes in the proportion of time spent in contact with the discriminative stimuli. PMID:7175427

Racial/ethnic discrimination and common mental disorders among workers: findings from the EMPIRIC Study of Ethnic Minority Groups in the United Kingdom.

PubMed

Bhui, Kamaldeep; Stansfeld, Stephen; McKenzie, Kwame; Karlsen, Saffron; Nazroo, James; Weich, Scott

2005-03-01

We measured perceived discrimination and its association with common mental disorders among workers in the United Kingdom. We conducted a secondary analysis of a national sample of 6 ethnic groups (n=2054). Discrimination was measured as reports of insults; unfair treatment at work; or job denial stemming from race, religion, or language. The outcome assessed was presence of common mental disorders. The risk of mental disorders was highest among ethnic minority individuals reporting unfair treatment (odds ratio [OR]=2.0; 95% confidence interval [CI]=1.2, 3.2) and racial insults (OR=2.3; 95% CI=1.4, 3.6). The overall greatest risks were observed among Black Caribbeans exposed to unfair treatment at work (OR=2.9; 95% CI=1.2, 7.3) and Indian (OR=3.1; 95% CI=1.4, 7.2), Bangladeshi (OR=32.9; 95% CI=2.5, 436.0), and Irish (OR=2.9; 95% CI=1.1, 7.6) individuals reporting insults. Racial/ethnic discrimination shows strong associations with common mental disorders.

[Bilateral cochlear implants].

PubMed

Müller, J

2017-07-01

Cochlear implants (CI) are standard for the hearing rehabilitation of severe to profound deafness. Nowadays, if bilaterally indicated, bilateral implantation is usually recommended (in accordance with German guidelines). Bilateral implantation enables better speech discrimination in quiet and in noise, and restores directional and spatial hearing. Children with bilateral CI are able to undergo hearing-based hearing and speech development. Within the scope of their individual possibilities, bilaterally implanted children develop faster than children with unilateral CI and attain, e.g., a larger vocabulary within a certain time interval. Only bilateral implantation allows "binaural hearing," with all the benefits that people with normal hearing profit from, namely: better speech discrimination in quiet and in noise, as well as directional and spatial hearing. Naturally, the developments take time. Binaural CI users benefit from the same effects as normal hearing persons: head shadow effect, squelch effect, and summation and redundancy effects. Sequential CI fitting is not necessarily disadvantageous-both simultaneously and sequentially fitted patients benefit in a similar way. For children, earliest possible fitting and shortest possible interval between the two surgeries seems to positively influence the outcome if bilateral CI are indicated.

The adaptive pattern of the auditory N1 peak revealed by standardized low-resolution brain electromagnetic tomography

PubMed Central

Zhang, Fawen; Deshpande, Aniruddha; Benson, Chelsea; Smith, Mathew; Eliassen, James; Fu, Qian-Jie

2011-01-01

The N1 peak in the late auditory evoked potential (LAEP) decreases in amplitude following stimulus repetition, displaying an adaptive pattern. The present study explored the functional neural substrates that may underlie the N1 adaptive pattern using standardized Low Resolution Electromagnetic Tomography (sLORETA). Fourteen young normal hearing (NH) listeners participated in the study. Tone bursts (80 dB SPL) were binaurally presented via insert earphones in trains of ten; the inter-stimulus interval was 0.7 s and the inter-train interval was 15 s. Current source density analysis was performed for the N1 evoked by the 1st, 2nd and 10th stimuli (S1, S2 and S10) at three different timeframes that corresponded to the latency ranges of the N1 waveform subcomponents (70–100, 100–130 and 130–160 ms). The data showed that S1 activated broad regions in different cortical lobes and the activation was much smaller for S2 and S10. Response differences in the LAEP waveform and sLORETA were observed between S1 and S2, but not between the S2 and S10. The sLORETA comparison map between S1 and S2 response showed the activation was located in the parietal lobe for the 70–100 ms timeframe, the frontal and limbic lobes for the 100–130 ms timeframe, and the frontal lobe for the 130–160 ms timeframe. These sLORETA comparison results suggest a parieto-frontal network that might help to sensitize the brain to novel stimuli by filtering out repetitive and irrelevant stimuli. This study demonstrates that sLORETA may be useful for identifying generators of scalp-recorded event related potentials and for examining the physiological features of these generators. This technique could be especially useful for cortical source localization in individuals who cannot be examined with functional magnetic resonance imaging or magnetoencephalography (e.g., cochlear implant users). PMID:21658681

The adaptive pattern of the auditory N1 peak revealed by standardized low-resolution brain electromagnetic tomography.

PubMed

Zhang, Fawen; Deshpande, Aniruddha; Benson, Chelsea; Smith, Mathew; Eliassen, James; Fu, Qian-Jie

2011-07-11

The N1 peak in the late auditory evoked potential (LAEP) decreases in amplitude following stimulus repetition, displaying an adaptive pattern. The present study explored the functional neural substrates that may underlie the N1 adaptive pattern using standardized Low Resolution Electromagnetic Tomography (sLORETA). Fourteen young normal hearing (NH) listeners participated in the study. Tone bursts (80 dB SPL) were binaurally presented via insert earphones in trains of 10; the inter-stimulus interval was 0.7s and the inter-train interval was 15s. Current source density analysis was performed for the N1 evoked by the 1st, 2nd and 10th stimuli (S(1), S(2) and S(10)) at 3 different timeframes that corresponded to the latency ranges of the N1 waveform subcomponents (70-100, 100-130 and 130-160 ms). The data showed that S(1) activated broad regions in different cortical lobes and the activation was much smaller for S(2) and S(10). Response differences in the LAEP waveform and sLORETA were observed between S(1) and S(2), but not between the S(2) and S(10). The sLORETA comparison map between S(1) and S(2) responses showed that the activation was located in the parietal lobe for the 70-100 ms timeframe, the frontal and limbic lobes for the 100-130 ms timeframe, and the frontal lobe for the 130-160 ms timeframe. These sLORETA comparison results suggest a parieto-frontal network that might help to sensitize the brain to novel stimuli by filtering out repetitive and irrelevant stimuli. This study demonstrates that sLORETA may be useful for identifying generators of scalp-recorded event related potentials and for examining the physiological features of these generators. This technique could be especially useful for cortical source localization in individuals who cannot be examined with functional magnetic resonance imaging or magnetoencephalography (e.g., cochlear implant users). Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluating dedicated and intrinsic models of temporal encoding by varying context

PubMed Central

Spencer, Rebecca M.C.; Karmarkar, Uma; Ivry, Richard B.

2009-01-01

Two general classes of models have been proposed to account for how people process temporal information in the milliseconds range. Dedicated models entail a mechanism in which time is explicitly encoded; examples include clock–counter models and functional delay lines. Intrinsic models, such as state-dependent networks (SDN), represent time as an emergent property of the dynamics of neural processing. An important property of SDN is that the encoding of duration is context dependent since the representation of an interval will vary as a function of the initial state of the network. Consistent with this assumption, duration discrimination thresholds for auditory intervals spanning 100 ms are elevated when an irrelevant tone is presented at varying times prior to the onset of the test interval. We revisit this effect in two experiments, considering attentional issues that may also produce such context effects. The disruptive effect of a variable context was eliminated or attenuated when the intervals between the irrelevant tone and test interval were made dissimilar or the duration of the test interval was increased to 300 ms. These results indicate how attentional processes can influence the perception of brief intervals, as well as point to important constraints for SDN models. PMID:19487188

Discrimination of bed form scales using robust spline filters and wavelet transforms: Methods and application to synthetic signals and bed forms of the Río Paraná, Argentina

NASA Astrophysics Data System (ADS)

Gutierrez, Ronald R.; Abad, Jorge D.; Parsons, Daniel R.; Best, James L.

2013-09-01

There is no standard nomenclature and procedure to systematically identify the scale and magnitude of bed forms such as bars, dunes, and ripples that are commonly present in many sedimentary environments. This paper proposes a standardization of the nomenclature and symbolic representation of bed forms and details the combined application of robust spline filters and continuous wavelet transforms to discriminate these morphodynamic features, allowing the quantitative recognition of bed form hierarchies. Herein the proposed methodology for bed form discrimination is first applied to synthetic bed form profiles, which are sampled at a Nyquist ratio interval of 2.5-50 and a signal-to-noise ratio interval of 1-20 and subsequently applied to a detailed 3-D bed topography from the Río Paraná, Argentina, which exhibits large-scale dunes with superimposed, smaller bed forms. After discriminating the synthetic bed form signals into three-bed form hierarchies that represent bars, dunes, and ripples, the accuracy of the methodology is quantified by estimating the reproducibility, the cross correlation, and the standard deviation ratio of the actual and retrieved signals. For the case of the field measurements, the proposed method is used to discriminate small and large dunes and subsequently obtain and statistically analyze the common morphological descriptors such as wavelength, slope, and amplitude of both stoss and lee sides of these different size bed forms. Analysis of the synthetic signals demonstrates that the Morlet wavelet function is the most efficient in retrieving smaller periodicities such as ripples and smaller dunes and that the proposed methodology effectively discriminates waves of different periods for Nyquist ratios higher than 25 and signal-to-noise ratios higher than 5. The analysis of bed forms in the Río Paraná reveals that, in most cases, a Gamma probability distribution, with a positive skewness, best describes the dimensionless wavelength and amplitude for both the lee and stoss sides of large dunes. For the case of smaller superimposed dunes, the dimensionless wavelength shows a discrete behavior that is governed by the sampling frequency of the data, and the dimensionless amplitude better fits the Gamma probability distribution, again with a positive skewness. This paper thus provides a robust methodology for systematically identifying the scales and magnitudes of bed forms in a range of environments.

Behavioral and Single-Neuron Sensitivity to Millisecond Variations in Temporally Patterned Communication Signals

PubMed Central

Baker, Christa A.; Ma, Lisa; Casareale, Chelsea R.

2016-01-01

In many sensory pathways, central neurons serve as temporal filters for timing patterns in communication signals. However, how a population of neurons with diverse temporal filtering properties codes for natural variation in communication signals is unknown. Here we addressed this question in the weakly electric fish Brienomyrus brachyistius, which varies the time intervals between successive electric organ discharges to communicate. These fish produce an individually stereotyped signal called a scallop, which consists of a distinctive temporal pattern of ∼8–12 electric pulses. We manipulated the temporal structure of natural scallops during behavioral playback and in vivo electrophysiology experiments to probe the temporal sensitivity of scallop encoding and recognition. We found that presenting time-reversed, randomized, or jittered scallops increased behavioral response thresholds, demonstrating that fish's electric signaling behavior was sensitive to the precise temporal structure of scallops. Next, using in vivo intracellular recordings and discriminant function analysis, we found that the responses of interval-selective midbrain neurons were also sensitive to the precise temporal structure of scallops. Subthreshold changes in membrane potential recorded from single neurons discriminated natural scallops from time-reversed, randomized, and jittered sequences. Pooling the responses of multiple neurons improved the discriminability of natural sequences from temporally manipulated sequences. Finally, we found that single-neuron responses were sensitive to interindividual variation in scallop sequences, raising the question of whether fish may analyze scallop structure to gain information about the sender. Collectively, these results demonstrate that a population of interval-selective neurons can encode behaviorally relevant temporal patterns with millisecond precision. SIGNIFICANCE STATEMENT The timing patterns of action potentials, or spikes, play important roles in representing information in the nervous system. However, how these temporal patterns are recognized by downstream neurons is not well understood. Here we use the electrosensory system of mormyrid weakly electric fish to investigate how a population of neurons with diverse temporal filtering properties encodes behaviorally relevant input timing patterns, and how this relates to behavioral sensitivity. We show that fish are behaviorally sensitive to millisecond variations in natural, temporally patterned communication signals, and that the responses of individual midbrain neurons are also sensitive to variation in these patterns. In fact, the output of single neurons contains enough information to discriminate stereotyped communication signals produced by different individuals. PMID:27559179

Behavioral and Single-Neuron Sensitivity to Millisecond Variations in Temporally Patterned Communication Signals.

PubMed

Baker, Christa A; Ma, Lisa; Casareale, Chelsea R; Carlson, Bruce A

2016-08-24

In many sensory pathways, central neurons serve as temporal filters for timing patterns in communication signals. However, how a population of neurons with diverse temporal filtering properties codes for natural variation in communication signals is unknown. Here we addressed this question in the weakly electric fish Brienomyrus brachyistius, which varies the time intervals between successive electric organ discharges to communicate. These fish produce an individually stereotyped signal called a scallop, which consists of a distinctive temporal pattern of ∼8-12 electric pulses. We manipulated the temporal structure of natural scallops during behavioral playback and in vivo electrophysiology experiments to probe the temporal sensitivity of scallop encoding and recognition. We found that presenting time-reversed, randomized, or jittered scallops increased behavioral response thresholds, demonstrating that fish's electric signaling behavior was sensitive to the precise temporal structure of scallops. Next, using in vivo intracellular recordings and discriminant function analysis, we found that the responses of interval-selective midbrain neurons were also sensitive to the precise temporal structure of scallops. Subthreshold changes in membrane potential recorded from single neurons discriminated natural scallops from time-reversed, randomized, and jittered sequences. Pooling the responses of multiple neurons improved the discriminability of natural sequences from temporally manipulated sequences. Finally, we found that single-neuron responses were sensitive to interindividual variation in scallop sequences, raising the question of whether fish may analyze scallop structure to gain information about the sender. Collectively, these results demonstrate that a population of interval-selective neurons can encode behaviorally relevant temporal patterns with millisecond precision. The timing patterns of action potentials, or spikes, play important roles in representing information in the nervous system. However, how these temporal patterns are recognized by downstream neurons is not well understood. Here we use the electrosensory system of mormyrid weakly electric fish to investigate how a population of neurons with diverse temporal filtering properties encodes behaviorally relevant input timing patterns, and how this relates to behavioral sensitivity. We show that fish are behaviorally sensitive to millisecond variations in natural, temporally patterned communication signals, and that the responses of individual midbrain neurons are also sensitive to variation in these patterns. In fact, the output of single neurons contains enough information to discriminate stereotyped communication signals produced by different individuals. Copyright © 2016 the authors 0270-6474/16/368985-16$15.00/0.

Predicting depression based on dynamic regional connectivity: a windowed Granger causality analysis of MEG recordings.

PubMed

Lu, Qing; Bi, Kun; Liu, Chu; Luo, Guoping; Tang, Hao; Yao, Zhijian

2013-10-16

Abnormal inter-regional causalities can be mapped for the objective diagnosis of various diseases. These inter-regional connectivities are usually calculated over an entire scan and used to characterize the stationary strength of the connections. However, the connectivity within networks may undergo substantial changes during a scan. In this study, we developed an objective depression recognition approach using the dynamic regional interactions that occur in response to sad facial stimuli. The whole time-period magnetoencephalography (MEG) signals from the visual cortex, amygdala, anterior cingulate cortex (ACC) and inferior frontal gyrus (IFG) were separated into sequential time intervals. The Granger causality mapping method was used to identify the pairwise interaction pattern within each time interval. Feature selection was then undertaken within a minimum redundancy-maximum relevance (mRMR) framework. Typical classifiers were utilized to predict those patients who had depression. The overall performances of these classifiers were similar, and the highest classification accuracy rate was 87.5%. The best discriminative performance was obtained when the number of features was within a robust range. The discriminative network pattern obtained through support vector machine (SVM) analyses displayed abnormal causal connectivities that involved the amygdala during the early and late stages. These early and late connections in the amygdala appear to reveal a negative bias to coarse expression information processing and abnormal negative modulation in patients with depression, which may critically affect depression discrimination. © 2013 Elsevier B.V. All rights reserved.

Factors affecting sensitivity to frequency change in school-age children and adults.

PubMed

Buss, Emily; Taylor, Crystal N; Leibold, Lori J

2014-10-01

The factors affecting frequency discrimination in school-age children are poorly understood. The goal of the present study was to evaluate developmental effects related to memory for pitch and the utilization of temporal fine structure. Listeners were 5.1- to 13.6-year-olds and adults, all with normal hearing. A subgroup of children had musical training. The task was a 3-alternative forced choice in which listeners identified the interval with the higher frequency tone or the tone characterized by frequency modulation (FM). The standard was 500 or 5000 Hz, and the FM rate was either 2 or 20 Hz. Thresholds tended to be higher for younger children than for older children and adults for all conditions, although this age effect was smaller for FM detection than for pure-tone frequency discrimination. Neither standard frequency nor modulation rate affected the child/adult difference FM thresholds. Children with musical training performed better than their peers on pure-tone frequency discrimination at 500 Hz. Testing frequency discrimination using a low-rate FM detection task may minimize effects related to cognitive factors like memory for pitch or training effects. Maturation of frequency discrimination does not appear to differ across conditions in which listeners are hypothesized to rely on temporal cues and place cues.

Speech feature discrimination in deaf children following cochlear implantation

NASA Astrophysics Data System (ADS)

Bergeson, Tonya R.; Pisoni, David B.; Kirk, Karen Iler

2002-05-01

Speech feature discrimination is a fundamental perceptual skill that is often assumed to underlie word recognition and sentence comprehension performance. To investigate the development of speech feature discrimination in deaf children with cochlear implants, we conducted a retrospective analysis of results from the Minimal Pairs Test (Robbins et al., 1988) selected from patients enrolled in a longitudinal study of speech perception and language development. The MP test uses a 2AFC procedure in which children hear a word and select one of two pictures (bat-pat). All 43 children were prelingually deafened, received a cochlear implant before 6 years of age or between ages 6 and 9, and used either oral or total communication. Children were tested once every 6 months to 1 year for 7 years; not all children were tested at each interval. By 2 years postimplant, the majority of these children achieved near-ceiling levels of discrimination performance for vowel height, vowel place, and consonant manner. Most of the children also achieved plateaus but did not reach ceiling performance for consonant place and voicing. The relationship between speech feature discrimination, spoken word recognition, and sentence comprehension will be discussed. [Work supported by NIH/NIDCD Research Grant No. R01DC00064 and NIH/NIDCD Training Grant No. T32DC00012.

Sporadic adult onset primary torsion dystonia is a genetic disorder by the temporal discrimination test.

PubMed

Kimmich, Okka; Bradley, David; Whelan, Robert; Mulrooney, Nicola; Reilly, Richard B; Hutchinson, Siobhan; O'Riordan, Sean; Hutchinson, Michael

2011-09-01

Adult-onset primary torsion dystonia is an autosomal dominant disorder with markedly reduced penetrance; patients with sporadic adult-onset primary torsion dystonia are much more prevalent than familial. The temporal discrimination threshold is the shortest time interval at which two stimuli are detected to be asynchronous and has been shown to be abnormal in adult-onset primary torsion dystonia. The aim was to determine the frequency of abnormal temporal discrimination thresholds in patients with sporadic adult-onset primary torsion dystonia and their first-degree relatives. We hypothesized that abnormal temporal discrimination thresholds in first relatives would be compatible with an autosomal dominant endophenotype. Temporal discrimination thresholds were examined in 61 control subjects (39 subjects <50 years of age; 22 subjects >50 years of age), 32 patients with sporadic adult-onset primary torsion dystonia (cervical dystonia n = 30, spasmodic dysphonia n = 1 and Meige's syndrome n = 1) and 73 unaffected first-degree relatives (36 siblings, 36 offspring and one parent) using visual and tactile stimuli. Z-scores were calculated for all subjects; a Z > 2.5 was considered abnormal. Abnormal temporal discrimination thresholds were found in 1/61 (2%) control subjects, 27/32 (84%) patients with adult-onset primary torsion dystonia and 32/73 (44%) unaffected relatives [siblings (20/36; 56%), offspring (11/36; 31%) and one parent]. When two or more relatives were tested in any one family, 22 of 24 families had at least one first-degree relative with an abnormal temporal discrimination threshold. The frequency of abnormal temporal discrimination thresholds in first-degree relatives of patients with sporadic adult-onset primary torsion dystonia is compatible with an autosomal dominant disorder and supports the hypothesis that apparently sporadic adult-onset primary torsion dystonia is genetic in origin.

Perceived Discrimination and Incident Cardiovascular Events: The Multi-Ethnic Study of Atherosclerosis.

PubMed

Everson-Rose, Susan A; Lutsey, Pamela L; Roetker, Nicholas S; Lewis, Tené T; Kershaw, Kiarri N; Alonso, Alvaro; Diez Roux, Ana V

2015-08-01

Perceived discrimination is positively related to cardiovascular disease (CVD) risk factors; its relationship with incident CVD is unknown. Using data from the Multi-Ethnic Study of Atherosclerosis, a population-based multiethnic cohort study of 6,508 adults aged 45-84 years who were initially free of clinical CVD, we examined lifetime discrimination (experiences of unfair treatment in 6 life domains) and everyday discrimination (frequency of day-to-day occurrences of perceived unfair treatment) in relation to incident CVD. During a median 10.1 years of follow-up (2000-2011), 604 incident events occurred. Persons reporting lifetime discrimination in ≥2 domains (versus none) had increased CVD risk, after adjustment for race/ethnicity and sociodemographic factors, behaviors, and traditional CVD risk factors (hazard ratio (HR) = 1.36, 95% confidence interval (CI): 1.09, 1.70) and after control for chronic stress and depressive symptoms (HR = 1.28, 95% CI: 1.01, 1.60). Reported discrimination in 1 domain was unrelated to CVD (HR = 1.05, 95% CI: 0.86, 1.30). There were no differences by race/ethnicity, age, or sex. In contrast, everyday discrimination interacted with sex (P = 0.03). Stratified models showed increased risk only among men (for each 1-standard deviation increase in score, adjusted HR = 1.14, 95% CI: 1.03, 1.27); controlling for chronic stress and depressive symptoms slightly reduced this association (HR = 1.11, 95% CI: 0.99, 1.25). This study suggests that perceived discrimination is adversely related to CVD risk in middle-aged and older adults. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Perceived discrimination, humiliation, and mental health: a mixed-methods study among Haitian migrants in the Dominican Republic.

PubMed

Keys, Hunter M; Kaiser, Bonnie N; Foster, Jennifer W; Burgos Minaya, Rosa Y; Kohrt, Brandon A

2015-01-01

Many Haitian migrants live and work as undocumented laborers in the Dominican Republic. This study examines the legacy of anti-Haitian discrimination in the Dominican Republic and association of discrimination with mental health among Haitian migrants. This study used mixed methods to generate hypotheses for associations between discrimination and mental health of Haitian migrants in the Dominican Republic. In-depth interviews were conducted with 21 Haitian and 18 Dominican community members and clinicians. One hundred and twenty-seven Haitian migrants participated in a pilot cross-sectional community survey. Instruments included culturally adapted Kreyòl versions of the Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI) and a locally developed function impairment scale. Haitian migrants described humiliation (imilyasyon) as a reason for mental distress and barrier to health care. Dominicans reported that discrimination (discriminación) was not a current social problem and attributed negative social interactions to sociocultural, behavioral, and biological differences between Dominicans and Haitians. These qualitative findings were supported in the quantitative analyses. Perceived discrimination was significantly associated with depression severity and functional impairment. Perceived mistreatment by Dominicans was associated with a 6.6-point increase in BDI score (90% confidence interval [CI]: 3.29, 9.9). Knowing someone who was interrogated or deported was associated with a 3.4-point increase in BAI score (90% CI: 0.22, 6.64). Both qualitative and quantitative methods suggest that perceived discrimination and the experience of humiliation contribute to Haitian migrant mental ill-health and limit access to health care. Future research should evaluate these associations and identify intervention pathways for both improved treatment access and reduction of discrimination-related health risk factors.

Temporal discrimination, a cervical dystonia endophenotype: penetrance and functional correlates.

PubMed

Kimmich, Okka; Molloy, Anna; Whelan, Robert; Williams, Laura; Bradley, David; Balsters, Joshua; Molloy, Fiona; Lynch, Tim; Healy, Daniel G; Walsh, Cathal; O'Riordan, Seán; Reilly, Richard B; Hutchinson, Michael

2014-05-01

The pathogenesis of adult-onset primary dystonia remains poorly understood. There is variable age-related and gender-related expression of the phenotype, the commonest of which is cervical dystonia. Endophenotypes may provide insight into underlying genetic and pathophysiological mechanisms of dystonia. The temporal discrimination threshold (TDT)-the shortest time interval at which two separate stimuli can be detected as being asynchronous-is abnormal both in patients with cervical dystonia and in their unaffected first-degree relatives. Functional magnetic resonance imaging (fMRI) studies have shown that putaminal activation positively correlates with the ease of temporal discrimination between two stimuli in healthy individuals. We hypothesized that abnormal temporal discrimination would exhibit similar age-related and gender-related penetrance as cervical dystonia and that unaffected relatives with an abnormal TDT would have reduced putaminal activation during a temporal discrimination task. TDTs were examined in a group of 192 healthy controls and in 158 unaffected first-degree relatives of 84 patients with cervical dystonia. In 24 unaffected first-degree relatives, fMRI scanning was performed during a temporal discrimination task. The prevalence of abnormal TDTs in unaffected female relatives reached 50% after age 48 years; whereas, in male relatives, penetrance of the endophenotype was reduced. By fMRI, relatives who had abnormal TDTs, compared with relatives who had normal TDTs, had significantly less activation in the putamina and in the middle frontal and precentral gyri. Only the degree of reduction of putaminal activity correlated significantly with worsening of temporal discrimination. These findings further support abnormal temporal discrimination as an endophenotype of cervical dystonia involving disordered basal ganglia circuits. © 2014 International Parkinson and Movement Disorder Society.

Harassment and discrimination in medical training: a systematic review and meta-analysis.

PubMed

Fnais, Naif; Soobiah, Charlene; Chen, Maggie Hong; Lillie, Erin; Perrier, Laure; Tashkhandi, Mariam; Straus, Sharon E; Mamdani, Muhammad; Al-Omran, Mohammed; Tricco, Andrea C

2014-05-01

Harassment and discrimination include a wide range of behaviors that medical trainees perceive as being humiliating, hostile, or abusive. To understand the significance of such mistreatment and to explore potential preventive strategies, the authors conducted a systematic review and meta-analysis to examine the prevalence, risk factors, and sources of harassment and discrimination among medical trainees. In 2011, the authors identified relevant studies by searching MEDLINE and EMBASE, scanning reference lists of relevant studies, and contacting experts. They included studies that reported the prevalence, risk factors, and sources of harassment and discrimination among medical trainees. Two reviewers independently screened all articles and abstracted study and participant characteristics and study results. The authors assessed the methodological quality in individual studies using the Newcastle-Ottawa Scale. They also conducted a meta-analysis. The authors included 57 cross-sectional and 2 cohort studies in their review. The meta-analysis of 51 studies demonstrated that 59.4% of medical trainees had experienced at least one form of harassment or discrimination during their training (95% confidence interval [CI]: 52.0%-66.7%). Verbal harassment was the most commonly cited form of harassment (prevalence: 63.0%; 95% CI: 54.8%-71.2%). Consultants were the most commonly cited source of harassment and discrimination, followed by patients or patients' families (34.4% and 21.9%, respectively). This review demonstrates the surprisingly high prevalence of harassment and discrimination among medical trainees that has not declined over time. The authors recommend both drafting policies and promoting cultural change within academic institutions to prevent future abuse.

Spectral discrimination of macrophyte species during different seasons in a tropical wetland using in-situ hyperspectral remote sensing

NASA Astrophysics Data System (ADS)

Saluja, Ridhi; Garg, J. K.

2017-10-01

Wetlands, one of the most productive ecosystems on Earth, perform myriad ecological functions and provide a host of ecological services. Despite their ecological and economic values, wetlands have experienced significant degradation during the last century and the trend continues. Hyperspectral sensors provide opportunities to map and monitor macrophyte species within wetlands for their management and conservation. In this study, an attempt has been made to evaluate the potential of narrowband spectroradiometer data in discriminating wetland macrophytes during different seasons. main objectives of the research were (1) to determine whether macrophyte species could be discriminated based on in-situ hyperspectral reflectance collected over different seasons and at each measured waveband (400-950nm), (2) to compare the effectiveness of spectral reflectance and spectral indices in discriminating macrophyte species, and (3) to identify spectral wavelengths that are most sensitive in discriminating macrophyte species. Spectral characteristics of dominant wetland macrophyte species were collected seasonally using SVC GER 1500 portable spectroradiometer over the 400 to 1050nm spectral range at 1.5nm interval, at the Bhindawas wetland in the state of Haryana, India. Hyperspectral observations were pre-processed and subjected to statistical analysis, which involved a two-step approach including feature selection (ANOVA and KW test) and feature extraction (LDA and PCA). Statistical analysis revealed that the most influential wavelengths for discrimination were distributed along the spectral profile from visible to the near-infrared regions. The results suggest that hyperspectral data can be used discriminate wetland macrophyte species working as an effective tool for advanced mapping and monitoring of wetlands.

Simple and conditional visual discrimination with wheel running as reinforcement in rats.

PubMed

Iversen, I H

1998-09-01

Three experiments explored whether access to wheel running is sufficient as reinforcement to establish and maintain simple and conditional visual discriminations in nondeprived rats. In Experiment 1, 2 rats learned to press a lit key to produce access to running; responding was virtually absent when the key was dark, but latencies to respond were longer than for customary food and water reinforcers. Increases in the intertrial interval did not improve the discrimination performance. In Experiment 2, 3 rats acquired a go-left/go-right discrimination with a trial-initiating response and reached an accuracy that exceeded 80%; when two keys showed a steady light, pressing the left key produced access to running whereas pressing the right key produced access to running when both keys showed blinking light. Latencies to respond to the lights shortened when the trial-initiation response was introduced and became much shorter than in Experiment 1. In Experiment 3, 1 rat acquired a conditional discrimination task (matching to sample) with steady versus blinking lights at an accuracy exceeding 80%. A trial-initiation response allowed self-paced trials as in Experiment 2. When the rat was exposed to the task for 19 successive 24-hr periods with access to food and water, the discrimination performance settled in a typical circadian pattern and peak accuracy exceeded 90%. When the trial-initiation response was under extinction, without access to running, the circadian activity pattern determined the time of spontaneous recovery. The experiments demonstrate that wheel-running reinforcement can be used to establish and maintain simple and conditional visual discriminations in nondeprived rats.

Auditory Processing, Linguistic Prosody Awareness, and Word Reading in Mandarin-Speaking Children Learning English

ERIC Educational Resources Information Center

Chung, Wei-Lun; Jarmulowicz, Linda; Bidelman, Gavin M.

2017-01-01

This study examined language-specific links among auditory processing, linguistic prosody awareness, and Mandarin (L1) and English (L2) word reading in 61 Mandarin-speaking, English-learning children. Three auditory discrimination abilities were measured: pitch contour, pitch interval, and rise time (rate of intensity change at tone onset).…

Self-reported racial discrimination, response to unfair treatment, and coronary calcification in asymptomatic adults--the North Texas Healthy Heart study.

PubMed

Cardarelli, Roberto; Cardarelli, Kathryn M; Fulda, Kimberly G; Espinoza, Anna; Cage, Clifton; Vishwanatha, Jamboor; Young, Richard; Steele, Darryl N; Carroll, Joan

2010-05-27

Accruing evidence supports the hypothesis that psychosocial factors are related to cardiovascular disease. However, a limited number of studies have investigated the pathophysiologic pathways through which these associations occur. The purpose of this study was to assess whether experiences of self-reported racial discrimination and reactions to unfair treatment were associated with coronary artery calcification (CAC), an indicator of subclinical coronary heart disease (CHD). This cross-sectional study recruited 571 subjects (45 years and older) who were asymptomatic of CHD from Fort Worth, Texas from 2006 to 2008. Subjects completed a questionnaire, a multi-slice computed tomography scan to assess for CAC presence (measured as Agatston score >0), and serum chemistries. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between self-reported discrimination and CAC. Results were stratified by response to unfair treatment as it was found to significantly modify the relationship between discrimination and CAC. Among those who passively responded to unfair treatment, the odds of having CAC present were approximately 3 times higher for those experiencing discrimination (OR, 2.95; 95% CI, 1.19-7.32) after adjusting for age, gender, race/ethnicity, education, body mass index, hyperlipidemia, smoking status, hypertension, diabetes, and first degree relative with heart disease. This is the first multi-racial/ethnic study to find racial discrimination associated with CAC, which differs based on how one responds to unfair treatment.

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.

Impact of cafeteria feeding during lactation in the rat on novel object discrimination in the offspring.

PubMed

Wright, Thomas M; King, Madeleine V; Davey, William G; Langley-Evans, Simon C; Voigt, Jörg-Peter W

2014-12-28

There is increasing evidence that hyperenergetic diets have an impact on memory in rodents. However, it is largely unknown how diets, such as a cafeteria diet (CD), that mimic a Western-type diet act on learning and memory, in particular when fed during early stages of development. Here, we fed lactating dams a CD and exposed both male and female offspring to a novel object discrimination (NOD) task, a two-trial test of recognition memory in which rats exposed to two identical objects during a training/familiarisation trial can discriminate a novel from a familiar object during the subsequent choice trial. The choice trial was performed following inter-trial interval (ITI) delays of up to 4 h. Maternal diet did not have an impact on exploration of the objects by either sex during the familiarisation trial. Control males discriminated the novel from the familiar object, indicating intact memory with an ITI of 1 h, but not 2 or 4 h. The CD delayed this natural forgetting in male rats such that discrimination was also evident after a 2 h ITI. In contrast, control females exhibited discrimination following both 1 and 2 h ITI, but the CD impaired performance. In summary, the present study shows that maternal exposure to the CD programmes NOD in the adult. In better-performing females, dietary programming interferes with NOD, whereas NOD was improved in males after lactational CD feeding.

Young Women do it Better: Sexual Dimorphism in Temporal Discrimination.

PubMed

Williams, Laura Jane; Butler, John S; Molloy, Anna; McGovern, Eavan; Beiser, Ines; Kimmich, Okka; Quinlivan, Brendan; O'Riordan, Sean; Hutchinson, Michael; Reilly, Richard B

2015-01-01

The temporal discrimination threshold (TDT) is the shortest time interval at which two sensory stimuli presented sequentially are detected as asynchronous by the observer. TDTs are known to increase with age. Having previously observed shorter thresholds in young women than in men, in this work we sought to systematically examine the effect of sex and age on temporal discrimination. The aims of this study were to examine, in a large group of men and women aged 20-65 years, the distribution of TDTs with an analysis of the individual participant's responses, assessing the "point of subjective equality" and the "just noticeable difference" (JND). These respectively assess sensitivity and accuracy of an individual's response. In 175 participants (88 women) aged 20-65 years, temporal discrimination was faster in women than in men under the age of 40 years by a mean of approximately 13 ms. However, age-related decline in temporal discrimination was three times faster in women so that, in the age group of 40-65 years, the female superiority was reversed. The point of subjective equality showed a similar advantage in younger women and more marked age-related decline in women than men, as the TDT. JND values declined equally in both sexes, showing no sexual dimorphism. This observed sexual dimorphism in temporal discrimination is important for both (a) future clinical research assessing disordered mid-brain covert attention in basal-ganglia disorders, and (b) understanding the biology of this sexual dimorphism which may be genetic or hormonal.

Measurement of trained speech patterns in stuttering: interjudge and intrajudge agreement of experts by means of modified time-interval analysis.

PubMed

Alpermann, Anke; Huber, Walter; Natke, Ulrich; Willmes, Klaus

2010-09-01

Improved fluency after stuttering therapy is usually measured by the percentage of stuttered syllables. However, outcome studies rarely evaluate the use of trained speech patterns that speakers use to manage stuttering. This study investigated whether the modified time interval analysis can distinguish between trained speech patterns, fluent speech, and stuttered speech. Seventeen German experts on stuttering judged a speech sample on two occasions. Speakers of the sample were stuttering adults, who were not undergoing therapy, as well as participants in a fluency shaping and a stuttering modification therapy. Results showed satisfactory inter-judge and intra-judge agreement above 80%. Intervals with trained speech patterns were identified as consistently as stuttered and fluent intervals. We discuss limitations of the study, as well as implications of our findings for the development of training for identification of trained speech patterns and future outcome studies. The reader will be able to (a) explain different methods to measure the use of trained speech patterns, (b) evaluate whether German experts are able to discriminate intervals with trained speech patterns reliably from fluent and stuttered intervals and (c) describe how the measurement of trained speech patterns can contribute to outcome studies.

The psychometric properties of Observer OPTION(5), an observer measure of shared decision making.

PubMed

Barr, Paul J; O'Malley, Alistair James; Tsulukidze, Maka; Gionfriddo, Michael R; Montori, Victor; Elwyn, Glyn

2015-08-01

Observer OPTION(5) was designed as a more efficient version of OPTION(12), the most commonly used measure of shared decision making (SDM). The current paper assesses the psychometric properties of OPTION(5). Two raters used OPTION(5) to rate recordings of clinical encounters from two previous patient decision aid (PDA) trials (n=201; n=110). A subsample was re-rated two weeks later. We assessed discriminative validity, inter-rater reliability, intra-rater reliability, and concurrent validity. OPTION(5) demonstrated discriminative validity, with increases in SDM between usual care and PDA arms. OPTION(5) also demonstrated concurrent validity with OPTION(12), r=0.61 (95%CI 0.54, 0.68) and intra-rater reliability, r=0.93 (0.83, 0.97). The mean difference in rater score was 8.89 (95% Credibility Interval, 7.5, 10.3), with intraclass correlation (ICC) of 0.67 (95% Credibility Interval, 0.51, 0.91) for the accuracy of rater scores and 0.70 (95% Credibility Interval, 0.56, 0.94) for the consistency of rater scores across encounters, indicating good inter-rater reliability. Raters reported lower cognitive burden when using OPTION(5) compared to OPTION(12). OPTION(5) is a brief, theoretically grounded observer measure of SDM with promising psychometric properties in this sample and low burden on raters. OPTION(5) has potential to provide reliable, valid assessment of SDM in clinical encounters. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Discriminating the precipitation phase based on different temperature thresholds in the Songhua River Basin, China

NASA Astrophysics Data System (ADS)

Zhong, Keyuan; Zheng, Fenli; Xu, Ximeng; Qin, Chao

2018-06-01

Different precipitation phases (rain, snow or sleet) differ greatly in their hydrological and erosional processes. Therefore, accurate discrimination of the precipitation phase is highly important when researching hydrologic processes and climate change at high latitudes and mountainous regions. The objective of this study was to identify suitable temperature thresholds for discriminating the precipitation phase in the Songhua River Basin (SRB) based on 20-year daily precipitation collected from 60 meteorological stations located in and around the basin. Two methods, the air temperature method (AT method) and the wet bulb temperature method (WBT method), were used to discriminate the precipitation phase. Thirteen temperature thresholds were used to discriminate snowfall in the SRB. These thresholds included air temperatures from 0 to 5.5 °C at intervals of 0.5 °C and the wet bulb temperature (WBT). Three evaluation indices, the error percentage of discriminated snowfall days (Ep), the relative error of discriminated snowfall (Re) and the determination coefficient (R2), were applied to assess the discrimination accuracy. The results showed that 2.5 °C was the optimum threshold temperature for discriminating snowfall at the scale of the entire basin. Due to differences in the landscape conditions at the different stations, the optimum threshold varied by station. The optimal threshold ranged 1.5-4.0 °C, and 19 stations, 17 stations and 18 stations had optimal thresholds of 2.5 °C, 3.0 °C, and 3.5 °C respectively, occupying 90% of all stations. Compared with using a single suitable temperature threshold to discriminate snowfall throughout the basin, it was more accurate to use the optimum threshold at each station to estimate snowfall in the basin. In addition, snowfall was underestimated when the temperature threshold was the WBT and when the temperature threshold was below 2.5 °C, whereas snowfall was overestimated when the temperature threshold exceeded 4.0 °C at most stations. The results of this study provide information for climate change research and hydrological process simulations in the SRB, as well as provide reference information for discriminating precipitation phase in other regions.

Perceived discrimination is associated with reduced breast and cervical cancer screening: the Study of Women's Health Across the Nation (SWAN).

PubMed

Jacobs, Elizabeth A; Rathouz, Paul J; Karavolos, Kelly; Everson-Rose, Susan A; Janssen, Imke; Kravitz, Howard M; Lewis, Tené T; Powell, Lynda H

2014-02-01

Racial disparities in breast and cervical cancer screening have been documented in African American, Hispanic, and Asian populations. Perceived discrimination may contribute to this disparity. The aim of this study was to understand the relationship between perceived everyday racial/ethnic and other discrimination and receipt of breast and cervical cancer screening in a multiethnic population of women. We analyzed data from 3,258 women participating in the Study of Women's Health Across the Nation (SWAN), a multiethnic/racial, longitudinal cohort study of the natural history of the menopausal transition conducted at seven U.S. sites. Participants completed a validated measure of perceived discrimination and reasons for believing that they were treated differently, along with Pap smears, clinical breast exams (CBE), and mammography at each follow-up period. We used multiple logistic regression for the binary outcomes of having a Pap smear, CBE, or mammogram in each of the two follow-up years, using self-reported "race discrimination" and "other discrimination" at baseline as the main predictors. African American women reported the highest percentage of racial discrimination (35%), followed by Chinese (20%), Hispanic (12%), Japanese (11%), and non-Hispanic white women (3%). Non-Hispanic white women reported the highest percentage of "other" discrimination (40%), followed by Chinese (33%), African American (24%), Japanese (23%), and Hispanic women (16%). Perceived racial discrimination was not associated with reduced receipt of preventive screening, except in one fully adjusted model. Reported discrimination owing to "other" reasons, such as age or gender, was associated with reduced receipt of Pap smear (odds ratio [OR] 0.85; 95% confidence interval [CI] 0.74-0.99), CBE (OR 0.78; 95% CI 0.67-0.91), and mammography (OR 0.80; 95% CI 0.69-0.92) regardless of patient race. Perceived discrimination is an important issue across racial/ethnic groups and is negatively associated with receipt of breast and cervical cancer screening. This is an important issue that needs to be further explored and addressed in efforts to improve the delivery of healthcare to all groups.

Gender discrimination, educational attainment, and illicit drug use among U.S. women

PubMed Central

Carliner, Hannah; Sarvet, Aaron L.; Gordon, Allegra R.; Hasin, Deborah S.

2016-01-01

Purpose While gender inequality has been a topic of concern for decades, little is known about the relationship between gender discrimination and illicit drug use. Further, whether this association varies by education level is unknown. Methods Among 19,209 women participants in Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (2004–2005), we used logistic regression to test the association between gender discrimination (measured with four items from the Experiences of Discrimination instrument) and three outcomes: past-year illicit drug use, frequent drug use, and drug use disorders. We then tested whether associations differed by education level. Results Gender discrimination was reported by 9% of women and was associated with past-year drug use (adjusted odds ratio [aOR]=2.67; 95% confidence interval [CI]=2.17–3.29), frequent drug use (aOR=2.82; CI=1.99–4.00), and past year drug use disorders (aOR=3.15; CI=2.16–4.61). All specific domains of gender discrimination (on the job, in public, with institutions, being called a sexist name) were associated with all drug use outcomes. The association between gender discrimination and past-year drug use was stronger among women with less than a high school education (aOR=6.33; CI=3.38–11.85) compared to those with more education (aOR=2.45; CI=1.97–3.04; pinteraction<0.01). Conclusions Gender discrimination is consistently and strongly associated with illicit drug use and drug use disorders among U.S. women, with significantly higher odds for drug use among women with less than a high school education. Future research should examine whether explicitly addressing distress from discrimination could benefit women in drug treatment, especially among clients with lower educational attainment. PMID:28025690

Olfactory discrimination predicts cognitive decline among community-dwelling older adults

PubMed Central

Sohrabi, H R; Bates, K A; Weinborn, M G; Johnston, A N B; Bahramian, A; Taddei, K; Laws, S M; Rodrigues, M; Morici, M; Howard, M; Martins, G; Mackay-Sim, A; Gandy, S E; Martins, R N

2012-01-01

The presence of olfactory dysfunction in individuals at higher risk of Alzheimer's disease has significant diagnostic and screening implications for preventive and ameliorative drug trials. Olfactory threshold, discrimination and identification can be reliably recorded in the early stages of neurodegenerative diseases. The current study has examined the ability of various olfactory functions in predicting cognitive decline in a community-dwelling sample. A group of 308 participants, aged 46–86 years old, were recruited for this study. After 3 years of follow-up, participants were divided into cognitively declined and non-declined groups based on their performance on a neuropsychological battery. Assessment of olfactory functions using the Sniffin' Sticks battery indicated that, contrary to previous findings, olfactory discrimination, but not olfactory identification, significantly predicted subsequent cognitive decline (odds ratio=0.869; P<0.05; 95% confidence interval=0.764−0.988). The current study findings confirm previously reported associations between olfactory and cognitive functions, and indicate that impairment in olfactory discrimination can predict future cognitive decline. These findings further our current understanding of the association between cognition and olfaction, and support olfactory assessment in screening those at higher risk of dementia. PMID:22832962

Olfactory discrimination predicts cognitive decline among community-dwelling older adults.

PubMed

Sohrabi, H R; Bates, K A; Weinborn, M G; Johnston, A N B; Bahramian, A; Taddei, K; Laws, S M; Rodrigues, M; Morici, M; Howard, M; Martins, G; Mackay-Sim, A; Gandy, S E; Martins, R N

2012-05-22

The presence of olfactory dysfunction in individuals at higher risk of Alzheimer's disease has significant diagnostic and screening implications for preventive and ameliorative drug trials. Olfactory threshold, discrimination and identification can be reliably recorded in the early stages of neurodegenerative diseases. The current study has examined the ability of various olfactory functions in predicting cognitive decline in a community-dwelling sample. A group of 308 participants, aged 46-86 years old, were recruited for this study. After 3 years of follow-up, participants were divided into cognitively declined and non-declined groups based on their performance on a neuropsychological battery. Assessment of olfactory functions using the Sniffin' Sticks battery indicated that, contrary to previous findings, olfactory discrimination, but not olfactory identification, significantly predicted subsequent cognitive decline (odds ratio = 0.869; P<0.05; 95% confidence interval = 0.764-0.988). The current study findings confirm previously reported associations between olfactory and cognitive functions, and indicate that impairment in olfactory discrimination can predict future cognitive decline. These findings further our current understanding of the association between cognition and olfaction, and support olfactory assessment in screening those at higher risk of dementia.

Attractor structure discriminates sleep states: recurrence plot analysis applied to infant breathing patterns.

PubMed

Terrill, Philip Ian; Wilson, Stephen James; Suresh, Sadasivam; Cooper, David M; Dakin, Carolyn

2010-05-01

Breathing patterns are characteristically different between infant active sleep (AS) and quiet sleep (QS), and statistical quantifications of interbreath interval (IBI) data have previously been used to discriminate between infant sleep states. It has also been identified that breathing patterns are governed by a nonlinear controller. This study aims to investigate whether nonlinear quantifications of infant IBI data are characteristically different between AS and QS, and whether they may be used to discriminate between these infant sleep states. Polysomnograms were obtained from 24 healthy infants at six months of age. Periods of AS and QS were identified, and IBI data extracted. Recurrence quantification analysis (RQA) was applied to each period, and recurrence calculated for a fixed radius in the range of 0-8 in steps of 0.02, and embedding dimensions of 4, 6, 8, and 16. When a threshold classifier was trained, the RQA variable recurrence was able to correctly classify 94.3% of periods in a test dataset. It was concluded that RQA of IBI data is able to accurately discriminate between infant sleep states. This is a promising step toward development of a minimal-channel automatic sleep state classification system.

Discrimination of phoneme length differences in word and sentence contexts

NASA Astrophysics Data System (ADS)

Kawai, Norimune; Carrell, Thomas

2005-09-01

The ability of listeners to discriminate phoneme duration differences within word and sentence contexts was measured. This investigation was part of a series of studies examining the audibility and perceptual importance of speech modifications produced by stuttering intervention techniques. Just noticeable differences (jnd's) of phoneme lengths were measured via the parameter estimation by sequential testing (PEST) task, an adaptive tracking procedure. The target phonemes were digitally manipulated to vary from normal (130 m) to prolonged (210 m) duration in 2-m increments. In the first condition the phonemes were embedded in words. In the second condition the phonemes were embedded within words, which were further embedded in sentences. A four-interval forced-choice (4IAX) task was employed on each trial, and the PEST procedure determined the duration at which each listener correctly detected a difference between the normal duration and the test duration 71% of the time. The results revealed that listeners were able to reliably discriminate approximately 15-m differences in word context and 10-m differences in sentence context. An independent t-test showed a difference in discriminability between word and sentence contexts to be significant. These results indicate that duration differences were better perceived within a sentence context.

Real-time cerebellar neuroprosthetic system based on a spiking neural network model of motor learning

NASA Astrophysics Data System (ADS)

Xu, Tao; Xiao, Na; Zhai, Xiaolong; Chan, Pak Kwan; Tin, Chung

2018-02-01

Objective. Damage to the brain, as a result of various medical conditions, impacts the everyday life of patients and there is still no complete cure to neurological disorders. Neuroprostheses that can functionally replace the damaged neural circuit have recently emerged as a possible solution to these problems. Here we describe the development of a real-time cerebellar neuroprosthetic system to substitute neural function in cerebellar circuitry for learning delay eyeblink conditioning (DEC). Approach. The system was empowered by a biologically realistic spiking neural network (SNN) model of the cerebellar neural circuit, which considers the neuronal population and anatomical connectivity of the network. The model simulated synaptic plasticity critical for learning DEC. This SNN model was carefully implemented on a field programmable gate array (FPGA) platform for real-time simulation. This hardware system was interfaced in in vivo experiments with anesthetized rats and it used neural spikes recorded online from the animal to learn and trigger conditioned eyeblink in the animal during training. Main results. This rat-FPGA hybrid system was able to process neuronal spikes in real-time with an embedded cerebellum model of ~10 000 neurons and reproduce learning of DEC with different inter-stimulus intervals. Our results validated that the system performance is physiologically relevant at both the neural (firing pattern) and behavioral (eyeblink pattern) levels. Significance. This integrated system provides the sufficient computation power for mimicking the cerebellar circuit in real-time. The system interacts with the biological system naturally at the spike level and can be generalized for including other neural components (neuron types and plasticity) and neural functions for potential neuroprosthetic applications.

Dysgraphia as a Mild Expression of Dystonia in Children with Absence Epilepsy

PubMed Central

Guerrini, Renzo; Melani, Federico; Brancati, Claudia; Ferrari, Anna Rita; Brovedani, Paola; Biggeri, Annibale; Grisotto, Laura; Pellacani, Simona

2015-01-01

Background Absence epilepsy (AE) is etiologically heterogeneous and has at times been associated with idiopathic dystonia. Objectives Based on the clinical observation that children with AE often exhibit, interictally, a disorder resembling writer’s cramp but fully definable as dysgraphia, we tested the hypothesis that in this particular population dysgraphia would represent a subtle expression of dystonia. Methods We ascertained the prevalence of dysgraphia in 82 children with AE (mean age 9.7) and average intelligence and compared them with 89 age-, gender- and class-matched healthy children (mean age 10.57) using tests for handwriting fluency and quality, based on which we divided patients and controls into four subgroups: AE/dysgraphia, AE without dysgraphia, controls with dysgraphia and healthy controls. We compared the blink reflex recovery cycle in children belonging to all four subgroups. Results We identified dysgraphia in 17/82 children with AE and in 7/89 controls (20.7 vs 7.8%; P = 0.016) with the former having a 3.4-times higher risk of dysgraphia regardless of age and gender (odd ratio: 3.49; 95% CI 1.2, 8.8%). The AE/dysgraphia subgroup performed worse than controls with dysgraphia in one test of handwriting fluency (P = 0.037) and in most trials testing handwriting quality (P< 0.02). In children with AE/dysgraphia the blink reflex showed no suppression at short interstimulus intervals, with a difference for each value emerging when comparing the study group with the three remaining subgroups (P<0.001). Conclusions In children with AE, dysgraphia is highly prevalent and has a homogeneous, distinctive pathophysiological substrate consistent with idiopathic dystonia. PMID:26132164

Mixed signals: The effect of conflicting reward- and goal-driven biases on selective attention.

PubMed

Preciado, Daniel; Munneke, Jaap; Theeuwes, Jan

2017-07-01

Attentional selection depends on the interaction between exogenous (stimulus-driven), endogenous (goal-driven), and selection history (experience-driven) factors. While endogenous and exogenous biases have been widely investigated, less is known about their interplay with value-driven attention. The present study investigated the interaction between reward-history and goal-driven biases on perceptual sensitivity (d') and response time (RT) in a modified cueing paradigm presenting two coloured cues, followed by sinusoidal gratings. Participants responded to the orientation of one of these gratings. In Experiment 1, one cue signalled reward availability but was otherwise task irrelevant. In Experiment 2, the same cue signalled reward, and indicated the target's most likely location at the opposite side of the display. This design introduced a conflict between reward-driven biases attracting attention and goal-driven biases directing it away. Attentional effects were examined comparing trials in which cue and target appeared at the same versus opposite locations. Two interstimulus interval (ISI) levels were used to probe the time course of attentional effects. Experiment 1 showed performance benefits at the location of the reward-signalling cue and costs at the opposite for both ISIs, indicating value-driven capture. Experiment 2 showed performance benefits only for the long ISI when the target was at the opposite to the reward-associated cue. At the short ISI, only performance costs were observed. These results reveal the time course of these biases, indicating that reward-driven effects influence attention early but can be overcome later by goal-driven control. This suggests that reward-driven biases are integrated as attentional priorities, just as exogenous and endogenous factors.

Concurrent functional magnetic resonance imaging and electroencephalography assessment of sensory gating in schizophrenia

PubMed Central

Bak, Nikolaj; Rostrup, Egill; Larsson, Henrik BW; Glenthøj, Birte Y; Oranje, Bob

2014-01-01

Schizophrenia is frequently accompanied by deficits in basic information processing, such as sensory gating. The sources behind deficient sensory gating in schizophrenia patients are, however, still largely unclear. The aim of the current study was to identify the brain structures involved in deficient sensory gating in schizophrenia patients. Twenty healthy male volunteers and 23 male schizophrenia patients were initially assessed in a somatosensory P50 suppression paradigm using concurrent electroencephalography (EEG)/functional magnetic resonance imaging (fMRI) methodology. The trials consisted of single stimuli or pairs of identical stimuli with either 500 ms or 1,000 ms interstimulus intervals. Not all subjects showed a P50 waveform as a result of the somatosensory stimuli: It was detected in 13 schizophrenia patients and 15 control subjects. Significant P50 suppression was found in the 500 ms trials in controls only. Region of interest analyses were performed for a priori chosen regions. Significant negative correlations between P50 ratios and the BOLD response were found bilaterally in the hippocampus, thalamus, anterior and posterior superior temporal gyrus (STG), and in the left inferior frontal gyrus pars opercularis. However, significant group differences were found in the hippocampus and the thalamus only. This is the first study in which P50 suppression was assessed in schizophrenia patients with concurrent fMRI/EEG methodology. The data support that the STG, thalamus, inferior frontal gyrus, and the hippocampus are involved in P50 suppression. However, of these structures only the hippocampus and thalamus appeared involved in the altered sensory processing found in schizophrenia. Hum Brain Mapp 35:3578–3587, 2014. © 2013 Wiley Periodicals, Inc. PMID:24375687

Sensitivity of the mouse to changes in azimuthal sound location: Angular separation, spectral composition, and sound level

PubMed Central

Allen, Paul D.; Ison, James R.

2010-01-01

Auditory spatial acuity was measured in mice using prepulse inhibition (PPI) of the acoustic startle reflex (ASR) as the indicator response for stimulus detection. The prepulse was a “speaker swap” (SSwap), shifting a noise between two speakers located along the azimuth. Their angular separation, and the spectral composition and sound level of the noise were varied, as was the interstimulus interval (ISI) between SSwap and ASR elicitation. In Experiment 1 a 180° SSwap of wide band noise (WBN) was compared with WBN Onset and Offset. SSwap and WBN Onset had near equal effects, but less than Offset. In Experiment 2 WBN SSwap was measured with speaker separations of 15°, 22.5°, 45°, and 90°. Asymptotic level and the growth rate of PPI increased with increased separation from 15° to 90°, but even the 15° SSwap provided significant PPI for the mean performance of the group. SSwap in Experiment 3 used octave band noise (2–4, 4–8, 8–16, or 16–32 kHz) and separations of 7.5° to 180°. SSwap was most effective for the highest frequencies, with no significant PPI for SSwap below 8–16 kHz, or for separations of 7.5°. In Experiment 4 SSwap had WBN sound levels from 40 to 78 dB SPL, and separations of 22.5°, 45°, 90° and 180°: PPI increased with level, this effect varying with ISI and angular separation. These experiments extend the prior findings on sound localization in mice, and the dependence of PPI on ISI adds a reaction-time-like dimension to this behavioral analysis. PMID:20364886

Interaction of reelin and stress on immobility in the forced swim test but not dopamine-mediated locomotor hyperactivity or prepulse inhibition disruption: Relevance to psychotic and mood disorders.

PubMed

Notaras, Michael J; Vivian, Billie; Wilson, Carey; van den Buuse, Maarten

2017-07-13

Psychotic disorders, such as schizophrenia, as well as some mood disorders, such as bipolar disorder, have been suggested to share common biological risk factors. One such factor is reelin, a large extracellular matrix glycoprotein that regulates neuronal migration during development as well as numerous activity-dependent processes in the adult brain. The current study sought to evaluate whether a history of stress exposure interacts with endogenous reelin levels to modify behavioural endophenotypes of relevance to psychotic and mood disorders. Heterozygous Reeler Mice (HRM) and wildtype (WT) controls were treated with 50mg/L of corticosterone (CORT) in their drinking water from 6 to 9weeks of age, before undergoing behavioural testing in adulthood. We assessed methamphetamine-induced locomotor hyperactivity, prepulse inhibition (PPI) of acoustic startle, short-term spatial memory in the Y-maze, and depression-like behaviour in the Forced-Swim Test (FST). HRM genotype or CORT treatment did not affect methamphetamine-induced locomotor hyperactivity, a model of psychosis-like behaviour. At baseline, HRM showed decreased PPI at the commonly used 100msec interstimulus interval (ISI), but not at the 30msec ISI or following challenge with apomorphine. A history of CORT exposure potentiated immobility in the FST amongst HRM, but not WT mice. In the Y-maze, chronic CORT treatment decreased novel arm preference amongst HRM, reflecting reduced short-term spatial memory. These data confirm a significant role of endogenous reelin levels on stress-related behaviour, supporting a possible role in both bipolar disorder and schizophrenia. However, an interaction of reelin deficiency with dopaminergic regulation of psychosis-like behaviour remains unclear. Copyright © 2017 Elsevier B.V. All rights reserved.

The basolateral amygdala can mediate the effects of fear memory on sleep independently of fear behavior and the peripheral stress response.

PubMed

Wellman, Laurie L; Fitzpatrick, Mairen E; Hallum, Olga Y; Sutton, Amy M; Williams, Brook L; Sanford, Larry D

2017-01-01

Fear conditioning associated with inescapable shock training (ST) and fearful context re-exposure (CR) alone can produce significant behavioral fear, a stress response and alterations in subsequent REM sleep. These alterations may vary among animals and are mediated by the basolateral nucleus of the amygdala (BLA). Here, we used the GABA A agonist, muscimol (Mus), to inactivate BLA prior to CR and examined the effects on sleep, freezing and stress-induced hyperthermia (SIH). Wistar rats (n=28) were implanted with electrodes for recording sleep, data loggers for recording core body temperature, and with cannulae aimed bilaterally into BLA. After recovery, the animals were habituated to the injection procedure and baseline sleep was recorded. On experimental day 1, rats received ST (20 footshocks, 0.8mA, 0.5s duration, 60s interstimulus interval). On experimental day 7, the rats received microinjections (0.5μl) into BLA of either Mus (1.0μM; n=13) or vehicle (Veh; n=15) prior to CR (CR1). On experimental day 21, the animals experienced a second CR (CR2) without Mus. For analysis, the rats were separated into 4 groups: (Veh-vulnerable (Veh-Vul; n=8), Veh-resilient (Veh-Res; n=7), Mus-vulnerable (Mus-Vul; n=7), and Mus-resilient (Mus-Res; n=6)) based on whether or not REM was decreased, compared to baseline, during the first 4h following ST. Pre-CR1 inactivation of BLA did not alter freezing or SIH, but did block the reduction in REM in the Mus-Vul group compared to the Veh-Vul group. These data indicate that BLA is an important region for mediating the effects of fearful memories on sleep. Copyright © 2016 Elsevier Inc. All rights reserved.

TMS activation of interhemispheric pathways between the posterior parietal cortex and the contralateral motor cortex

PubMed Central

Koch, Giacomo; Ruge, Diane; Cheeran, Binith; Fernandez Del Olmo, Miguel; Pecchioli, Cristiano; Marconi, Barbara; Versace, Viviana; Lo Gerfo, Emanuele; Torriero, Sara; Oliveri, Massimiliano; Caltagirone, Carlo; Rothwell, John C

2009-01-01

Using a twin coil transcranial magnetic stimulation (tc-TMS) approach we have previously demonstrated that facilitation may be detected in the primary motor cortex (M1) following stimulation over the ipsilateral caudal intraparietal sulcus (cIPS). Here we tested the interhemispheric interactions between the IPS and the contralateral motor cortex (M1). We found that conditioning the right cIPS facilitated contralateral M1 when the conditioning stimulus had an intensity of 90% resting motor threshold (RMT) but not at 70% or 110% RMT. Facilitation was maximal when the interstimulus interval (ISI) between cIPS and M1 was 6 or 12 ms. These facilitatory effects were mediated by interactions with specific groups of interneurons in the contralateral M1. In fact, short intracortical inhibition (SICI) was reduced following cIPS stimulation. Moreover, additional comparison of facilitation of responses evoked by anterior–posterior versus posterior–anterior stimulation of M1 suggested that facilitation was more effective on early I1/I2 circuits than on I3 circuits. In contrast to these effects, stimulation of anterior IPS (aIPS) at 90% RMT induced inhibition, instead of facilitation, of contralateral M1 at ISIs of 10–12 ms. Finally, we found similar facilitation between left cIPS and right M1 although the conditioning stimuli had to have a higher intensity compared with stimulation of right cIPS (110% instead of 90% RMT). These findings demonstrate that different subregions of the posterior parietal cortex (PPC) in humans exert both facilitatory and inhibitory effects towards the contralateral primary motor cortex. These corticocortical projections could contribute to a variety of motor tasks such as bilateral manual coordination, movement planning in space and grasping. PMID:19622612

Diversity of coding profiles of mechanoreceptors in glabrous skin of kittens.

PubMed

Gibson, J M; Beitel, R E; Welker, W

1975-03-21

We examined stimulul-response (S-R) profiles of 35 single mechanoreceptive afferent units having small receptive fields in glabrous forepaw skin of 24 anesthetized domestic kittens. Single unit activity was recorded with tungsten microelectrodes from cervical dorsal root ganglia. The study was designed to be as quantitatively descriptive as possible. We indented each unit's receptive field with a broad battery of simple, carefully controlled stimuli whose major parameters, including amplitude, velocity, acceleration, duration, and interstimulus interval were systematically varied. Stimuli were delivered by a small probe driven by a feedback-controlled axial displacement generator. Single unit discharge data were analyzed by a variety of direct and derived measures including dot patterns, peristimulus histograms, instantaneous and mean instantaneous firing rates, tuning curves, thresholds for amplitude and velocity, adaptation rates, dynamic and static sensitivities, and others. We found that with respect to any of the S-R transactions examined, the properties of our sample of units were continuously and broadly distributed. Any one unit might exhibit either a slow or rapid rate of adaptation, or might superficially appear to preferentially code a single stimulus parameter such as amplitude or velocity. But when the entire range of responsiveness of units to the entire stimulus battery was surveyed by a variety of analytic techniques, we were unable to find any justifiable basis for designation of discrete categories of S-R profiles. Intermediate response types were always found, and in general, all units were both broadly tuned and capable of responding to integrals of several stimulus parameters, our data argue against the usefulness of evaluating a unit's S-R coding capabilities by means of a limited ste of stimulation of response analysis procedures.

Cortico-cortical and motor evoked potentials to single and paired-pulse stimuli: An exploratory transcranial magnetic and intracranial electric brain stimulation study.

PubMed

Boulogne, Sébastien; Andre-Obadia, Nathalie; Kimiskidis, Vasilios K; Ryvlin, Philippe; Rheims, Sylvain

2016-11-01

Paired-pulse (PP) paradigms are commonly employed to assess in vivo cortical excitability using transcranial magnetic stimulation (TMS) to stimulate the primary motor cortex and modulate the induced motor evoked potential (MEP). Single-pulse cortical direct electrical stimulation (DES) during intracerebral EEG monitoring allows the investigation of brain connectivity by eliciting cortico-cortical evoked potentials (CCEPs). However, PP paradigm using intracerebral DES has rarely been reported and has never been previously compared with TMS. The work was intended (i) to verify that the well-established modulations of MEPs following PP TMS remain similar using DES in the motor cortex, and (ii) to evaluate if a similar pattern could be observed in distant cortico-cortical connections through modulations of CCEP. Three patients undergoing intracerebral EEG monitoring with electrodes implanted in the central region were studied. Single-pulse DES (1-3 mA, 1 ms, 0.2 Hz) and PP DES using six interstimulus intervals (5, 15, 30, 50, 100, and 200 ms) in the motor cortex with concomitant recording of CCEPs and MEPs in contralateral muscles were performed. Finally, a navigated PP TMS session targeted the intracranial stimulation site to record TMS-induced MEPs in two patients. MEP modulations elicited by PP intracerebral DES proved similar among the three patients and to those obtained by PP TMS. CCEP modulations elicited by PP intracerebral DES usually showed a pattern comparable to that of MEP, although a different pattern could be observed occasionally. PP intracerebral DES seems to involve excitatory and inhibitory mechanisms similar to PP TMS and allows the recording of intracortical inhibition and facilitation modulation on cortico-cortical connections. Hum Brain Mapp 37:3767-3778, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Modulation of motor cortex excitability by paired peripheral and transcranial magnetic stimulation.

PubMed

Kumru, Hatice; Albu, Sergiu; Rothwell, John; Leon, Daniel; Flores, Cecilia; Opisso, Eloy; Tormos, Josep Maria; Valls-Sole, Josep

2017-10-01

Repetitive application of peripheral electrical stimuli paired with transcranial magnetic stimulation (rTMS) of M1 cortex at low frequency, known as paired associative stimulation (PAS), is an effective method to induce motor cortex plasticity in humans. Here we investigated the effects of repetitive peripheral magnetic stimulation (rPMS) combined with low frequency rTMS ('magnetic-PAS') on intracortical and corticospinal excitability and whether those changes were widespread or circumscribed to the cortical area controlling the stimulated muscle. Eleven healthy subjects underwent three 10min stimulation sessions: 10HzrPMS alone, applied in trains of 5 stimuli every 10s (60 trains) on the extensor carpi radialis (ECR) muscle; rTMS alone at an intensity 120% of ECR threshold, applied over motor cortex of ECR and at a frequency of 0.1Hz (60 stimuli) and magnetic PAS, i.e., paired rPMS and rTMS. We recorded motor evoked potentials (MEPs) from ECR and first dorsal interosseous (FDI) muscles. We measured resting motor threshold, motor evoked potentials (MEP) amplitude at 120% of RMT, short intracortical inhibition (SICI) at interstimulus interval (ISI) of 2ms and intracortical facilitation (ICF) at an ISI of 15ms before and immediately after each intervention. Magnetic-PAS , but not rTMS or rPMS applied separately, increased MEP amplitude and reduced short intracortical inhibition in ECR but not in FDI muscle. Magnetic-PAS can increase corticospinal excitability and reduce intracortical inhibition. The effects may be specific for the area of cortical representation of the stimulated muscle. Application of magnetic-PAS might be relevant for motor rehabilitation. Copyright © 2017 International Federation of Clinical Neurophysiology. All rights reserved.

The influence of expertise and of physical complexity on visual short-term memory consolidation.

PubMed

Sun, Huiming; Zimmer, Hubert D; Fu, Xiaolan

2011-04-01

We investigated whether the expertise of a perceiver and the physical complexity of a stimulus influence consolidation of visual short-term memory (VSTM) in a S1-S2 (Stimulus 1-Stimulus 2) change detection task. Consolidation is assumed to make transient perceptual representations in VSTM more durable, and it is investigated by postexposure of a mask shortly after offset of the perceived stimulus (S1; 17 to 483 ms). We presented colours, Chinese characters, pseudocharacters, and novel symbols to novices (Germans) or experts of Chinese language (Chinese readers). Physical complexity was manipulated by the number of strokes. Unfamiliar material was remembered worse than familiar material (Experiments 1, 2, and 3). For novices the absolute VSTM performance was better for physically simple than for complex material, whereas for experts the complexity did not matter-Chinese readers memorized Chinese characters (Experiment 3). Articulatory suppression did not change these effects (Experiment 2). We always observed a strong effect of SOA, but this effect was influenced neither by physical complexity nor by expertise; only the length of the interstimulus interval between S1 and the mask was relevant. This was observed even with short stimulus onset asynchrony (SOA) of 100 ms (Experiment 2) and in comparing colours and characters (Experiment 5). However, masks impaired memory if they were presented at the locations of the to-be-memorized items, but not beside them-that is, interference was location-based (Experiment 6). We explain the effect of SOA by the assumption that it takes time to stop encoding of information presented at item locations with the offset of S1. The increasing resistance against interference by irrelevant material appears as consolidation of S1.

Gap prepulse inhibition of the auditory late response in healthy subjects.

PubMed

Ku, Yunseo; Ahn, Joong Woo; Kwon, Chiheon; Suh, Myung-Whan; Lee, Jun Ho; Oh, Seung Ha; Kim, Hee Chan

2015-11-01

The gap-startle paradigm has been used as a behavioral method for tinnitus screening in animal studies. This study aimed to investigate gap prepulse inhibition (GPI) of the auditory late response (ALR) as the objective response of the gap-intense sound paradigm in humans. ALRs were recorded in response to gap-intense and no-gap-intense sound stimuli in 27 healthy subjects. The amplitudes of the baseline-to-peak (N1, P2, and N2) and the peak-to-peak (N1P2 and P2N2) were compared between two averaged ALRs. The variations in the inhibition ratios of N1P2 and P2N2 during the experiment were analyzed by increasing stimuli repetitions. The effect of stimulus parameter adjustments on GPI ratios was evaluated. No-gap-intense sound stimuli elicited greater peak amplitudes than gap-intense sound stimuli, and significant differences were found across all peaks. The overall mean inhibition ratios were significantly lower than 1.0, where the value 1.0 indicates that there were no differences between gap-intense and no-gap-intense sound responses. The initial decline in GPI ratios was shown in N1P2 and P2N2 complexes, and this reduction was nearly complete after 100 stimulus repetitions. Significant effects of gap length and interstimulus interval on GPI ratios were observed. We found significant inhibition of ALR peak amplitudes in performing the gap-intense sound paradigm in healthy subjects. The N1P2 complex represented GPI well in terms of suppression degree and test-retest reliability. Our findings offer practical information for the comparative study of healthy subjects and tinnitus patients using the gap-intense sound paradigm with the ALR. © 2015 Society for Psychophysiological Research.

Hemispheric asymmetries in processing L1 and L2 idioms: effects of salience and context.

PubMed

Cieślicka, Anna B; Heredia, Roberto R

2011-03-01

This study investigates the contribution of the left and right hemispheres to the comprehension of bilingual figurative language and the joint effects of salience and context on the differential cerebral involvement in idiom processing. The divided visual field and the lexical decision priming paradigms were employed to examine the activation of salient and nonsalient ambiguous idiom interpretations (i.e., literal vs. non-literal) in the two hemispheres. Literally plausible ambiguous idioms, L1 (Polish) and L2 (English), were embedded in unconstraining ambiguous (e.g., I knew he kept an ace up his sleeve) or constraining unambiguous context clearly favoring their conventional idiomatic interpretation (e.g., The debating president kept an ace up his sleeve). Idioms were presented centrally, followed by laterally presented targets related to the figurative (e.g., GAIN) or literal (e.g., SHIRT) meaning of the idiom and displayed at Interstimulus Intervals (ISIs) of 0 ms (Experiment 1), 300 ms (Experiment 2), and 800 ms (Experiment 3). Results indicate that context and salience effects are significantly modulated by the language (native vs. nonnative) of the stimulus materials being presented to each hemisphere. Literal facilitation was found for L2 idioms in all three ISI conditions, which supports the notion of the special status that literal meanings of L2 idioms enjoy in the course of their processing by nonnative language users. No significant differences were found between the right and left hemispheres in regards to their sensitivity to contextual constraints. Results are discussed in terms of the Graded Salience Hypothesis and the Fine/Coarse Coding Theory. Copyright © 2010 Elsevier Inc. All rights reserved.

Early ERP Signature of Hearing Impairment in Visual Rhyme Judgment

PubMed Central

Classon, Elisabet; Rudner, Mary; Johansson, Mikael; Rönnberg, Jerker

2013-01-01

Postlingually acquired hearing impairment (HI) is associated with changes in the representation of sound in semantic long-term memory. An indication of this is the lower performance on visual rhyme judgment tasks in conditions where phonological and orthographic cues mismatch, requiring high reliance on phonological representations. In this study, event-related potentials (ERPs) were used for the first time to investigate the neural correlates of phonological processing in visual rhyme judgments in participants with acquired HI and normal hearing (NH). Rhyme task word pairs rhymed or not and had matching or mismatching orthography. In addition, the inter-stimulus interval (ISI) was manipulated to be either long (800 ms) or short (50 ms). Long ISIs allow for engagement of explicit, top-down processes, while short ISIs limit the involvement of such mechanisms. We hypothesized lower behavioral performance and N400 and N2 deviations in HI in the mismatching rhyme judgment conditions, particularly in short ISI. However, the results showed a different pattern. As expected, behavioral performance in the mismatch conditions was lower in HI than in NH in short ISI, but ERPs did not differ across groups. In contrast, HI performed on a par with NH in long ISI. Further, HI, but not NH, showed an amplified N2-like response in the non-rhyming, orthographically mismatching condition in long ISI. This was also the rhyme condition in which participants in both groups benefited the most from the possibility to engage top-down processes afforded with the longer ISI. Taken together, these results indicate an early ERP signature of HI in this challenging phonological task, likely reflecting use of a compensatory strategy. This strategy is suggested to involve increased reliance on explicit mechanisms such as articulatory recoding and grapheme-to-phoneme conversion. PMID:23653613

Does abnormal interhemispheric inhibition play a role in mirror dystonia?

PubMed

Sattler, Virginie; Dickler, Maya; Michaud, Martin; Meunier, Sabine; Simonetta-Moreau, Marion

2014-05-01

The presence of mirror dystonia (dystonic movement induced by a specific task performed by the unaffected hand) in the dominant hand of writer's cramp patients when the nondominant hand is moved suggests an abnormal interaction between the 2 hemispheres. In this study we compare the level of interhemispheric inhibition (IHI) in 2 groups of patients with writer's cramp, one with the presence of a mirror dystonia and the other without as well as a control group. The level of bidirectional IHI was measured in wrist muscles with dual-site transcranial magnetic stimulation with a 10-millisecond (short IHI) and a 40-millisecond (long IHI) interstimulus interval during rest and while holding a pen in 9 patients with mirror dystonia 7 without mirror dystonia, and 13 controls. The group of patients without mirror dystonia did not differ from the controls in their IHI level. In contrast, IHI was significantly decreased in the group of patients with mirror dystonia in comparison with the group without mirror dystonia and the controls in both wrist muscles of both the dystonic and unaffected hand whatever the resting or active condition (P = 0.001). The decrease of IHI level in the group of patients with mirror dystonia was negatively correlated with the severity and the duration of the disease: the weaker the level of IHI, the more severe was the disease and the longer its duration. Interhemispheric inhibition disturbances are most likely involved in the occurrence of mirror dystonia. This bilateral deficient inhibition further suggests the involvement of the unaffected hemisphere in the pathophysiology of unilateral dystonia. © 2013 International Parkinson and Movement Disorder Society.

Intracortical excitability in patients with relapsing-remitting and secondary progressive multiple sclerosis.

PubMed

Conte, A; Lenzi, D; Frasca, V; Gilio, F; Giacomelli, E; Gabriele, M; Bettolo, C Marini; Iacovelli, E; Pantano, P; Pozzilli, C; Inghilleri, M

2009-06-01

We designed this study to investigate possible correlations between variables measuring primary motor cortex excitability detected by single and paired-pulse transcranial magnetic stimulation (TMS) and the severity of clinical manifestations in patients with multiple sclerosis (MS). Thirty patients with MS in remission, 16 with relapsing-remitting (RR), 14 with secondary progressive disease (SP) and 17 healthy subjects participated in the study. In each subject, the central motor conduction time (CMCT) was calculated, and single-pulse and paired-pulse TMS at 3 and 10 ms interstimulus intervals was delivered over the primary motor cortex of the dominant hemisphere to measure the amplitude of motor-evoked potentials (MEPs), motor threshold (MTh), intracortical inhibition (ICI) and facilitation (ICF). Correlations were determined between the patients' TMS findings and magnetic resonance imaging (MRI) (lesion load) and clinical features (expanded disability status scale, EDSS score). EDSS scores were significantly higher in SPMS than in RRMS patients. The MTh was significantly higher, and the MEP was significantly smaller in SPMS patients than in RRMS patients and control subjects. All patients had longer CMCTs than healthy subjects. In all patients, paired-pulse TMS elicited an inhibited test MEP at the 3-ms ISI and a facilitated test MEP at the 10 ms ISI. Post hoc analysis showed that ICI was significantly lower in SPMS patients than in those with RRMS and healthy subjects. EDSS scores correlated significantly with TMS measures (MEP, ICI, CMCT and MTh), but not with MRI lesion load. It was found that intracortical excitability as measured with TMS differs according to the clinical course of MS; it remains normal in patients with low EDSS scores and is altered in patients with high EDSS scores.

Effects of inverting contour and features on processing for static and dynamic face perception: an MEG study.

PubMed

Miki, Kensaku; Takeshima, Yasuyuki; Watanabe, Shoko; Honda, Yukiko; Kakigi, Ryusuke

2011-04-06

We investigated the effects of inverting facial contour (hair and chin) and features (eyes, nose and mouth) on processing for static and dynamic face perception using magnetoencephalography (MEG). We used apparent motion, in which the first stimulus (S1) was replaced by a second stimulus (S2) with no interstimulus interval and subjects perceived visual motion, and presented three conditions as follows: (1) U&U: Upright contour and Upright features, (2) U&I: Upright contour and Inverted features, and (3) I&I: Inverted contour and Inverted features. In static face perception (S1 onset), the peak latency of the fusiform area's activity, which was related to static face perception, was significantly longer for U&I and I&I than for U&U in the right hemisphere and for U&I than for U&U and I&I in the left. In dynamic face perception (S2 onset), the strength (moment) of the occipitotemporal area's activity, which was related to dynamic face perception, was significantly larger for I&I than for U&U and U&I in the right hemisphere, but not the left. These results can be summarized as follows: (1) in static face perception, the activity of the right fusiform area was more affected by the inversion of features while that of the left fusiform area was more affected by the disruption of the spatial relation between the contour and features, and (2) in dynamic face perception, the activity of the right occipitotemporal area was affected by the inversion of the facial contour. Copyright © 2011 Elsevier B.V. All rights reserved.

The Basolateral Amygdala Can Mediate the Effects of Fear Memory on Sleep Independently of Fear Behavior and the Peripheral Stress Response

PubMed Central

Wellman, Laurie L.; Fitzpatrick, Mairen E.; Hallum, Olga Y.; Sutton, Amy M.; Williams, Brook L.; Sanford, Larry D.

2016-01-01

Fear conditioning associated with inescapable shock training (ST) and fearful context re-exposure (CR) alone can produce significant behavioral fear, a stress response and alterations in subsequent REM sleep. These alterations may vary among animals and are mediated by the basolateral nucleus of the amygdala (BLA). Here, we used the GABAA agonist, muscimol (Mus), to inactivate BLA prior to CR and examined the effects on sleep, freezing and stress-induced hyperthermia (SIH). Wistar rats (n=28) were implanted with electrodes for recording sleep, data loggers for recording core body temperature, and with cannulae aimed bilaterally into BLA. After recovery, the animals were habituated to the injection procedure and baseline sleep was recorded. On experimental day 1, rats received ST (20 footshocks, 0.8mA, 0.5s duration, 60s interstimulus interval). On experimental day 7, the rats received microinjections (0.5ul) into BLA of either Mus (1.0uM; n = 13) or vehicle (Veh; n = 15) prior to CR (CR1). On experimental day 21, the animals experienced a second CR (CR2) without Mus. For analysis, the rats were separated into 4 groups: (Veh-vulnerable (Veh-Vul; n=8), Veh-resilient (Veh-Res; n=7), Mus-vulnerable (Mus-Vul; n=7), and Mus-resilient (Mus-Res; n=6)) based on whether or not REM was decreased, compared to baseline, during the first 4 h following ST. Pre-CR1 inactivation of BLA did not alter freezing or SIH, but did block the reduction in REM in the Mus-Vul group compared to the Veh-Vul group. These data indicate that BLA is an important region for mediating the effects of fearful memories on sleep. PMID:27818268

Ethanol modulates cortical activity: direct evidence with combined TMS and EEG.

PubMed

Kähkönen, S; Kesäniemi, M; Nikouline, V V; Karhu, J; Ollikainen, M; Holi, M; Ilmoniemi, R J

2001-08-01

The motor cortex of 10 healthy subjects was stimulated by transcranial magnetic stimulation (TMS) before and after ethanol challenge (0.8 g/kg resulting in blood concentration of 0.77 +/- 0.14 ml/liter). The electrical brain activity resulting from the brief electromagnetic pulse was recorded with high-resolution electroencephalography (EEG) and located using inversion algorithms. Focal magnetic pulses to the left motor cortex were delivered with a figure-of-eight coil at the random interstimulus interval of 1.5-2.5 s. The stimulation intensity was adjusted to the motor threshold of abductor digiti minimi. Two conditions before and after ethanol ingestion (30 min) were applied: (1) real TMS, with the coil pressed against the scalp; and (2) control condition, with the coil separated from the scalp by a 2-cm-thick piece of plastic. A separate EMG control recording of one subject during TMS was made with two bipolar platinum needle electrodes inserted to the left temporal muscle. In each condition, 120 pulses were delivered. The EEG was recorded from 60 scalp electrodes. A peak in the EEG signals was observed at 43 ms after the TMS pulse in the real-TMS condition but not in the control condition or in the control scalp EMG. Potential maps before and after ethanol ingestion were significantly different from each other (P = 0.01), but no differences were found in the control condition. Ethanol changed the TMS-evoked potentials over right frontal and left parietal areas, the underlying effect appearing to be largest in the right prefrontal area. Our findings suggest that ethanol may have changed the functional connectivity between prefrontal and motor cortices. This new noninvasive method provides direct evidence about the modulation of cortical connectivity after ethanol challenge. Copyright 2001 Academic Press.

Immunotoxic cholinergic lesions in the basal forebrain reverse the effects of entorhinal cortex lesions on conditioned odor aversion in the rat.

PubMed

Ferry, Barbara; Herbeaux, Karin; Cosquer, Brigitte; Traissard, Natalia; Galani, Rodrigue; Cassel, Jean-Christophe

2007-07-01

Conditioned odor aversion (COA) corresponds to the avoidance of an odorized-tasteless solution (conditioned stimulus, CS) previously paired with toxicosis. COA occurs only when the interstimulus interval (ISI) is kept short, suggesting that the memory trace of the odor is subject to rapid decay. Previous experiments have shown that the entorhinal cortex (EC) is involved in the acquisition of COA, since lesion of the EC rendered COA tolerant to long ISI. Because EC lesions induce a septo-hippocampal cholinergic sprouting, the present experiment investigated whether COA tolerance to long ISI may be linked to this sprouting reaction. In a first experiment, male Long-Evans rats subjected to bilateral excitotoxic EC lesions combined to intracerebroventricular infusions of the selective cholinergic immunotoxin 192 IgG-saporin were exposed to odor-toxicosis pairing using a long ISI (120 min). Results showed that EC-lesioned rats displayed COA with the long ISI but not the control groups. In rats with EC combined to 192 IgG-saporin lesions, histological analysis demonstrated no evidence for cholinergic septo-hippocampal sprouting. In a second experiment, animals with 192-IgG saporin lesion showed a marked COA with a short ISI (5 min). These results suggest that the COA with the long ISI found in rats with EC lesions might involve a functional activity related to the EC lesion-induced hippocampal cholinergic sprouting. As the injection of 192 IgG-saporin alone did not affect COA with a short ISI, our data also point to a possible role of hippocampal cholinergic neurons in the modulation of memory processes underlying COA.

Effect of Different Movement Speed Modes on Human Action Observation: An EEG Study.

PubMed

Luo, Tian-Jian; Lv, Jitu; Chao, Fei; Zhou, Changle

2018-01-01

Action observation (AO) generates event-related desynchronization (ERD) suppressions in the human brain by activating partial regions of the human mirror neuron system (hMNS). The activation of the hMNS response to AO remains controversial for several reasons. Therefore, this study investigated the activation of the hMNS response to a speed factor of AO by controlling the movement speed modes of a humanoid robot's arm movements. Since hMNS activation is reflected by ERD suppressions, electroencephalography (EEG) with BCI analysis methods for ERD suppressions were used as the recording and analysis modalities. Six healthy individuals were asked to participate in experiments comprising five different conditions. Four incremental-speed AO tasks and a motor imagery (MI) task involving imaging of the same movement were presented to the individuals. Occipital and sensorimotor regions were selected for BCI analyses. The experimental results showed that hMNS activation was higher in the occipital region but more robust in the sensorimotor region. Since the attended information impacts the activations of the hMNS during AO, the pattern of hMNS activations first rises and subsequently falls to a stable level during incremental-speed modes of AO. The discipline curves suggested that a moderate speed within a decent inter-stimulus interval (ISI) range produced the highest hMNS activations. Since a brain computer/machine interface (BCI) builds a path-way between human and computer/mahcine, the discipline curves will help to construct BCIs made by patterns of action observation (AO-BCI). Furthermore, a new method for constructing non-invasive brain machine brain interfaces (BMBIs) with moderate AO-BCI and motor imagery BCI (MI-BCI) was inspired by this paper.

Handedness-related asymmetry in transmission in a system of human cervical premotoneurones.

PubMed

Marchand-Pauvert, V; Mazevet, D; Pierrot-Deseilligny, E; Pol, S; Pradat-Diehl, P

1999-04-01

The possibility was investigated that human handedness is associated with an asymmetrical cortical and/or peripheral control of the cervical premotoneurones (PreMNs) that have been shown to mediate part of the descending command to motoneurones of forearm muscles. Heteronymous facilitation evoked in the ongoing voluntary extensor carpi radialis (ECR) electromyographic activity (EMG) by weak (0.8 times motor threshold) stimulation of the musculo-cutaneous (MC) nerve was assessed during tonic co-contraction of biceps and ECR. Suppression evoked by stimulation of a cutaneous nerve (superficial radial, SR) at 4 times perception threshold in both the voluntary EMG and in the motor evoked potential (MEP) elicited in ECR by transcranial magnetic stimulation (TMS) was investigated during isolated ECR contraction. Measurements were performed within time windows or at interstimulus intervals where peripheral and cortical inputs may interact at the level of PreMNs. Results obtained on both sides were compared in consistent right- and left-handers. MC-induced facilitation of the voluntary ECR EMG was significantly larger on the preferred side, whereas there was no asymmetry in the SR-evoked depression of the ongoing ECR EMG. In addition, the suppression of the ECR MEP by the same SR stimulation was more pronounced on the dominant side during unilateral, but not during bilateral, ECR contraction. It is argued that (1) asymmetry in MC-induced facilitation of the voluntary EMG reflects a greater efficiency of the peripheral heteronymous volley in facilitating PreMNs on the dominant side; (2) asymmetry in SR-induced suppression of the MEP during unilateral ECR contraction, which is not paralleled by a similar asymmetry of voluntary EMG suppression, reflects a higher excitability of cortical neurones controlling inhibitory spinal pathways to cervical PreMNs on the preferred side.

Exploring the tolerability of spatiotemporally complex electrical stimulation paradigms.

PubMed

Nelson, Timothy S; Suhr, Courtney L; Lai, Alan; Halliday, Amy J; Freestone, Dean R; McLean, Karen J; Burkitt, Anthony N; Cook, Mark J

2011-10-01

A modified cortical stimulation model was used to investigate the effects of varying the synchronicity and periodicity of electrical stimuli delivered to multiple pairs of electrodes on seizure initiation. In this model, electrical stimulation of the motor cortex of rats, along four pairs of a microwire electrode array, results in an observable seizure with quantifiable electrographic duration and behavioural severity. Periodic stimuli had a constant inter-stimulus intervals across the two-second stimulus duration, whilst synchronous stimuli consisted of singular biphasic, bipolar pulses delivered to the four pairs of electrodes at precisely the same time for the entire two second stimulation period. In this way four combinations of stimulation were possible; periodic/synchronous (P/S), periodic/asynchronous (P/As), aperiodic/synchronous (Ap/S) and aperiodic/asynchronous (Ap/As). All stimulation types were designed with equal pulse width, current intensity and mean frequency of stimulation (60 Hz), standardizing net charge transfer. It was expected that the periodicity of the stimulus would be the primary determinant of seizure initiation and therefore severity and electrographic duration. However, the results showed that significant differences in both severity and duration only occurred when the synchronicity was altered. For periodic stimuli, synchronous delivery increased median seizure duration from 5 s to 13 s and increased median Racine severity from 1 to 3. In the aperiodic case, synchronous stimulus delivery increased median duration from 5.5 s to 11s and resulted in seizures of median severity 3 vs. 0 in the asynchronous case. These findings may have implications for the design of future neurostimulation waveform designs as higher numbers of electrodes and stimulator output channels become available in next generation implants. Copyright © 2011 Elsevier B.V. All rights reserved.

Neural substrates of behavioral variability in attention deficit hyperactivity disorder: based on ex-Gaussian reaction time distribution and diffusion spectrum imaging tractography.

PubMed

Lin, H-Y; Gau, S S-F; Huang-Gu, S L; Shang, C-Y; Wu, Y-H; Tseng, W-Y I

2014-06-01

Increased intra-individual variability (IIV) in reaction time (RT) across various tasks is one ubiquitous neuropsychological finding in attention deficit hyperactivity disorder (ADHD). However, neurobiological underpinnings of IIV in individuals with ADHD have not yet been fully delineated. The ex-Gaussian distribution has been proved to capture IIV in RT. The authors explored the three parameters [μ (mu), σ (sigma), τ (tau)] of an ex-Gaussian RT distribution derived from the Conners' continuous performance test (CCPT) and their correlations with the microstructural integrity of the frontostriatal-caudate tracts and the cingulum bundles. We assessed 28 youths with ADHD (8-17 years; 25 males) and 28 age-, sex-, IQ- and handedness-matched typically developing (TD) youths using the CCPT, Wechsler Intelligence Scale for Children, 3rd edition and magnetic resonance imaging (MRI). Microstructural integrity, indexed by generalized fractional anisotropy (GFA), was measured by diffusion spectrum imaging tractrography on a 3-T MRI system. Youths with ADHD had larger σ (s.d. of Gaussian distribution) and τ (mean of exponential distribution) and reduced GFA in four bilateral frontostriatal tracts. With increased inter-stimulus intervals of CCPT, the magnitude of greater τ in ADHD than TD increased. In ADHD youths, the cingulum bundles and frontostriatal integrity were associated with three ex-Gaussian parameters and with μ (mean of Gaussian distribution) and τ, respectively; while only frontostriatal GFA was associated with μ and τ in TD youths. Our findings suggest the crucial role of the integrity of the cingulum bundles in accounting for IIV in ADHD. Involvement of different brain systems in mediating IIV may relate to a distinctive pathophysiological processing and/or adaptive compensatory mechanism.

Neural mechanisms of phonemic restoration for speech comprehension revealed by magnetoencephalography.

PubMed

Sunami, Kishiko; Ishii, Akira; Takano, Sakurako; Yamamoto, Hidefumi; Sakashita, Tetsushi; Tanaka, Masaaki; Watanabe, Yasuyoshi; Yamane, Hideo

2013-11-06

In daily communication, we can usually still hear the spoken words as if they had not been masked and can comprehend the speech when spoken words are masked by background noise. This phenomenon is known as phonemic restoration. Since little is known about the neural mechanisms underlying phonemic restoration for speech comprehension, we aimed to identify the neural mechanisms using magnetoencephalography (MEG). Twelve healthy male volunteers with normal hearing participated in the study. Participants were requested to carefully listen to and understand recorded spoken Japanese stories, which were either played forward (forward condition) or in reverse (reverse condition), with their eyes closed. Several syllables of spoken words were replaced by 300-ms white-noise stimuli with an inter-stimulus interval of 1.6-20.3s. We compared MEG responses to white-noise stimuli during the forward condition with those during the reverse condition using time-frequency analyses. Increased 3-5 Hz band power in the forward condition compared with the reverse condition was continuously observed in the left inferior frontal gyrus [Brodmann's areas (BAs) 45, 46, and 47] and decreased 18-22 Hz band powers caused by white-noise stimuli were seen in the left transverse temporal gyrus (BA 42) and superior temporal gyrus (BA 22). These results suggest that the left inferior frontal gyrus and left transverse and superior temporal gyri are involved in phonemic restoration for speech comprehension. Our findings may help clarify the neural mechanisms of phonemic restoration as well as develop innovative treatment methods for individuals suffering from impaired speech comprehension, particularly in noisy environments. © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Decoding fMRI events in sensorimotor motor network using sparse paradigm free mapping and activation likelihood estimates.

PubMed

Tan, Francisca M; Caballero-Gaudes, César; Mullinger, Karen J; Cho, Siu-Yeung; Zhang, Yaping; Dryden, Ian L; Francis, Susan T; Gowland, Penny A

2017-11-01

Most functional MRI (fMRI) studies map task-driven brain activity using a block or event-related paradigm. Sparse paradigm free mapping (SPFM) can detect the onset and spatial distribution of BOLD events in the brain without prior timing information, but relating the detected events to brain function remains a challenge. In this study, we developed a decoding method for SPFM using a coordinate-based meta-analysis method of activation likelihood estimation (ALE). We defined meta-maps of statistically significant ALE values that correspond to types of events and calculated a summation overlap between the normalized meta-maps and SPFM maps. As a proof of concept, this framework was applied to relate SPFM-detected events in the sensorimotor network (SMN) to six motor functions (left/right fingers, left/right toes, swallowing, and eye blinks). We validated the framework using simultaneous electromyography (EMG)-fMRI experiments and motor tasks with short and long duration, and random interstimulus interval. The decoding scores were considerably lower for eye movements relative to other movement types tested. The average successful rate for short and long motor events were 77 ± 13% and 74 ± 16%, respectively, excluding eye movements. We found good agreement between the decoding results and EMG for most events and subjects, with a range in sensitivity between 55% and 100%, excluding eye movements. The proposed method was then used to classify the movement types of spontaneous single-trial events in the SMN during resting state, which produced an average successful rate of 22 ± 12%. Finally, this article discusses methodological implications and improvements to increase the decoding performance. Hum Brain Mapp 38:5778-5794, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Decoding fMRI events in Sensorimotor Motor Network using Sparse Paradigm Free Mapping and Activation Likelihood Estimates

PubMed Central

Tan, Francisca M.; Caballero-Gaudes, César; Mullinger, Karen J.; Cho, Siu-Yeung; Zhang, Yaping; Dryden, Ian L.; Francis, Susan T.; Gowland, Penny A.

2017-01-01

Most fMRI studies map task-driven brain activity using a block or event-related paradigm. Sparse Paradigm Free Mapping (SPFM) can detect the onset and spatial distribution of BOLD events in the brain without prior timing information; but relating the detected events to brain function remains a challenge. In this study, we developed a decoding method for SPFM using a coordinate-based meta-analysis method of Activation Likelihood Estimation (ALE). We defined meta-maps of statistically significant ALE values that correspond to types of events and calculated a summation overlap between the normalized meta-maps and SPFM maps. As a proof of concept, this framework was applied to relate SPFM-detected events in the Sensorimotor Network (SMN) to six motor function (left/right fingers, left/right toes, swallowing and eye blinks). We validated the framework using simultaneous Electromyography-fMRI experiments and motor tasks with short and long duration, and random inter-stimulus interval. The decoding scores were considerably lower for eye movements relative to other movement types tested. The average successful rate for short and long motor events was 77 ± 13% and 74 ± 16% respectively, excluding eye movements. We found good agreement between the decoding results and EMG for most events and subjects, with a range in sensitivity between 55 and 100%, excluding eye movements. The proposed method was then used to classify the movement types of spontaneous single-trial events in the SMN during resting state, which produced an average successful rate of 22 ± 12%. Finally, this paper discusses methodological implications and improvements to increase the decoding performance. PMID:28815863

Presentation-order effects for aesthetic stimulus preference.

PubMed

Englund, Mats P; Hellström, Åke

2012-10-01

For preference comparisons of paired successive musical excerpts, Koh (American Journal of Psychology, 80, 171-185, 1967) found time-order effects (TOEs) that correlated negatively with stimulus valence-the first (vs. the second) of two unpleasant (vs. two pleasant) excerpts tended to be preferred. We present three experiments designed to investigate whether valence-level-dependent order effects for aesthetic preference (a) can be accounted for using Hellström's (e.g., Journal of Experimental Psychology: Human Perception and Performance, 5, 460-477, 1979) sensation-weighting (SW) model, (b) can be generalized to successive and to simultaneous visual stimuli, and (c) vary, in accordance with the stimulus weighting, with interstimulus interval (ISI; for successive stimuli) or stimulus duration (for simultaneous stimuli). Participants compared paired successive jingles (Exp. 1), successive color patterns (Exp. 2), and simultaneous color patterns (Exp. 3), selecting the preferred stimulus. The results were well described by the SW model, which provided a better fit than did two extended versions of the Bradley-Terry-Luce model. Experiments 1 and 2 revealed higher weights for the second stimulus than for the first, and negatively valence-level-dependent TOEs. In Experiment 3, there was no laterality effect on the stimulus weighting and no valence-level-dependent space-order effects (SOEs). In terms of the SW model, the valence-level-dependent TOEs can be explained as a consequence of differential stimulus weighting in combination with stimulus valence varying from low to high, and the absence of valence-level-dependent SOEs as a consequence of the absence of differential weighting. For successive stimuli, there were no important effects of ISI on weightings and TOEs, and, for simultaneous stimuli, duration had only a small effect on the weighting.

Discrimination and Cumulative Disease Damage Among African American Women With Systemic Lupus Erythematosus.

PubMed

Chae, David H; Drenkard, Cristina M; Lewis, Tené T; Lim, S Sam

2015-10-01

We examined associations between unfair treatment, attributions of unfair treatment to racial discrimination, and cumulative disease damage among African American women with systemic lupus erythematosus (SLE). We used multivariable regression models to examine SLE damage among 578 African American women in metropolitan Atlanta, Georgia, recruited to the Georgians Organized Against Lupus cohort. When we controlled for demographic, socioeconomic, and health-related covariates, reporting any unfair treatment was associated with greater SLE damage compared with reporting no unfair treatment (b = 0.55; 95% confidence interval = 0.14, 0.97). In general, unfair treatment attributed to nonracial factors was more strongly associated with SLE damage than was unfair treatment attributed to racial discrimination, although the difference was not statistically significant. Unfair treatment may contribute to worse disease outcomes among African American women with SLE. Unfair treatment attributed to nonracial causes may have a more pronounced negative effect on SLE damage. Future research may further examine possible differences in the effect of unfair treatment by attribution.

Autoshaping of abnormal children.

PubMed

Deckner, C W; Wilcox, L M; Maisto, S A; Blanton, R L

1980-09-01

Three experimentally naive abnormal children were exposed to a terminal operant contingency, i.e., reinforcement was delivered only if the children pressed a panel during intervals when it was lighted. Despite the absence of both successive approximation and manual shaping, it was found that each child began to respond discriminatively within a small number of trials. These data replicated previous animal studies concerned with the phenomena of autoshaping and signal-controlled responding. It was also found, however, that one type of autoshaping, the classical conditioning procedure, had a powerful suppressive effect on the discriminative responding. An experimental analysis that consisted procedure, had a powerful suppressive effect on discriminative responding. An experimental analysis that consisted of intrasubject reversal an multiple baseline designs established the internal validity of the findings. The finding of rapid acquisition of signal-controlled responding obtained with the initial procedure is suggessted to have practical significance. The disruptive effects of the classical form of autoshaping are discussed in terms of negative behavioral contrast.

Central tendency effects in time interval reproduction in autism

PubMed Central

Karaminis, Themelis; Cicchini, Guido Marco; Neil, Louise; Cappagli, Giulia; Aagten-Murphy, David; Burr, David; Pellicano, Elizabeth

2016-01-01

Central tendency, the tendency of judgements of quantities (lengths, durations etc.) to gravitate towards their mean, is one of the most robust perceptual effects. A Bayesian account has recently suggested that central tendency reflects the integration of noisy sensory estimates with prior knowledge representations of a mean stimulus, serving to improve performance. The process is flexible, so prior knowledge is weighted more heavily when sensory estimates are imprecise, requiring more integration to reduce noise. In this study we measure central tendency in autism to evaluate a recent theoretical hypothesis suggesting that autistic perception relies less on prior knowledge representations than typical perception. If true, autistic children should show reduced central tendency than theoretically predicted from their temporal resolution. We tested autistic and age- and ability-matched typical children in two child-friendly tasks: (1) a time interval reproduction task, measuring central tendency in the temporal domain; and (2) a time discrimination task, assessing temporal resolution. Central tendency reduced with age in typical development, while temporal resolution improved. Autistic children performed far worse in temporal discrimination than the matched controls. Computational simulations suggested that central tendency was much less in autistic children than predicted by theoretical modelling, given their poor temporal resolution. PMID:27349722

Virtual active touch using randomly patterned intracortical microstimulation.

PubMed

O'Doherty, Joseph E; Lebedev, Mikhail A; Li, Zheng; Nicolelis, Miguel A L

2012-01-01

Intracortical microstimulation (ICMS) has promise as a means for delivering somatosensory feedback in neuroprosthetic systems. Various tactile sensations could be encoded by temporal, spatial, or spatiotemporal patterns of ICMS. However, the applicability of temporal patterns of ICMS to artificial tactile sensation during active exploration is unknown, as is the minimum discriminable difference between temporally modulated ICMS patterns. We trained rhesus monkeys in an active exploration task in which they discriminated periodic pulse-trains of ICMS (200 Hz bursts at a 10 Hz secondary frequency) from pulse trains with the same average pulse rate, but distorted periodicity (200 Hz bursts at a variable instantaneous secondary frequency). The statistics of the aperiodic pulse trains were drawn from a gamma distribution with mean inter-burst intervals equal to those of the periodic pulse trains. The monkeys distinguished periodic pulse trains from aperiodic pulse trains with coefficients of variation 0.25 or greater. Reconstruction of movement kinematics, extracted from the activity of neuronal populations recorded in the sensorimotor cortex concurrent with the delivery of ICMS feedback, improved when the recording intervals affected by ICMS artifacts were removed from analysis. These results add to the growing evidence that temporally patterned ICMS can be used to simulate a tactile sense for neuroprosthetic devices.

Image jitter enhances visual performance when spatial resolution is impaired.

PubMed

Watson, Lynne M; Strang, Niall C; Scobie, Fraser; Love, Gordon D; Seidel, Dirk; Manahilov, Velitchko

2012-09-06

Visibility of low-spatial frequency stimuli improves when their contrast is modulated at 5 to 10 Hz compared with stationary stimuli. Therefore, temporal modulations of visual objects could enhance the performance of low vision patients who primarily perceive images of low-spatial frequency content. We investigated the effect of retinal-image jitter on word recognition speed and facial emotion recognition in subjects with central visual impairment. Word recognition speed and accuracy of facial emotion discrimination were measured in volunteers with AMD under stationary and jittering conditions. Computer-driven and optoelectronic approaches were used to induce retinal-image jitter with duration of 100 or 166 ms and amplitude within the range of 0.5 to 2.6° visual angle. Word recognition speed was also measured for participants with simulated (Bangerter filters) visual impairment. Text jittering markedly enhanced word recognition speed for people with severe visual loss (101 ± 25%), while for those with moderate visual impairment, this effect was weaker (19 ± 9%). The ability of low vision patients to discriminate the facial emotions of jittering images improved by a factor of 2. A prototype of optoelectronic jitter goggles produced similar improvement in facial emotion discrimination. Word recognition speed in participants with simulated visual impairment was enhanced for interjitter intervals over 100 ms and reduced for shorter intervals. Results suggest that retinal-image jitter with optimal frequency and amplitude is an effective strategy for enhancing visual information processing in the absence of spatial detail. These findings will enable the development of novel tools to improve the quality of life of low vision patients.

Ruling out Legionella in community-acquired pneumonia.

PubMed

Haubitz, Sebastian; Hitz, Fabienne; Graedel, Lena; Batschwaroff, Marcus; Wiemken, Timothy Lee; Peyrani, Paula; Ramirez, Julio A; Fux, Christoph Andreas; Mueller, Beat; Schuetz, Philipp

2014-10-01

Assessing the likelihood for Legionella sp. in community-acquired pneumonia is important because of differences in treatment regimens. Currently used antigen tests and culture have limited sensitivity with important time delays, making empirical broad-spectrum coverage necessary. Therefore, a score with 6 variables recently has been proposed. We sought to validate these parameters in an independent cohort. We analyzed adult patients with community-acquired pneumonia from a large multinational database (Community Acquired Pneumonia Organization) who were treated between 2001 and 2012 with more than 4 of the 6 prespecified clinical variables available. Association and discrimination were assessed using logistic regression analysis and area under the curve (AUC). Of 1939 included patients, the infectious cause was known in 594 (28.9%), including Streptococcus pneumoniae in 264 (13.6%) and Legionella sp. in 37 (1.9%). The proposed clinical predictors fever, cough, hyponatremia, lactate dehydrogenase, C-reactive protein, and platelet count were all associated or tended to be associated with Legionella cause. A logistic regression analysis including all these predictors showed excellent discrimination with an AUC of 0.91 (95% confidence interval, 0.87-0.94). The original dichotomized score showed good discrimination (AUC, 0.73; 95% confidence interval, 0.65-0.81) and a high negative predictive value of 99% for patients with less than 2 parameters present. With the use of a large independent patient sample from an international database, this analysis validates previously proposed clinical variables to accurately rule out Legionella sp., which may help to optimize initial empiric therapy. Copyright © 2014 Elsevier Inc. All rights reserved.

BMI and an Anthropometry-Based Estimate of Fat Mass Percentage Are Both Valid Discriminators of Cardiometabolic Risk: A Comparison with DXA and Bioimpedance

PubMed Central

Völgyi, Eszter; Savonen, Kai; Tylavsky, Frances A.; Alén, Markku; Cheng, Sulin

2013-01-01

Objective. To determine whether categories of obesity based on BMI and an anthropometry-based estimate of fat mass percentage (FM% equation) have similar discriminative ability for markers of cardiometabolic risk as measurements of FM% by dual-energy X-ray absorptiometry (DXA) or bioimpedance analysis (BIA). Design and Methods. A study of 40–79-year-old male (n = 205) and female (n = 388) Finns. Weight, height, blood pressure, triacylglycerols, HDL cholesterol, and fasting blood glucose were measured. Body composition was assessed by DXA and BIA and a FM%-equation. Results. For grade 1 hypertension, dyslipidaemia, and impaired fasting glucose >6.1 mmol/L, the categories of obesity as defined by BMI and the FM% equation had 1.9% to 3.7% (P < 0.01) higher discriminative power compared to DXA. For grade 2 hypertension the FM% equation discriminated 1.2% (P = 0.05) lower than DXA and 2.8% (P < 0.01) lower than BIA. Receiver operation characteristics confirmed BIA as best predictor of grade 2 hypertension and the FM% equation as best predictor of grade 1 hypertension. All other differences in area under curve were small (≤0.04) and 95% confidence intervals included 0. Conclusions. Both BMI and FM% equations may predict cardiometabolic risk with similar discriminative ability as FM% measured by DXA or BIA. PMID:24455216

Role of discriminative stimuli in modulating drug action. [Pigeons

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

Laties, V.G.

1975-08-01

Behavior reinforced in the presence of a stimulus comes under the control of the stimulus. A drug can then modify that control and, therefore, modify the behavior itself. Studies over the past 2 decades have shown that the nature of the controlling (or discriminative) stimulus can govern the degree to which drugs change performance. These experiments usually have compared behavior on various schedules of reinforcement with and withoout added discriminative stimuli. For instance, pigeons that had been trained on a fixed-interval schedule showed great changes in response distribution after amphetamine and scopolamine. The same birds, when performing on a fixed-intervalmore » schedule to which time-correlated discriminative stimuli had been added, showed smaller changes in response distribution. Other pigeons were trained to make a minimum number of consecutive responses on one key before a peck on a second key would be reinforced; d-amphetamine and scopolamine led to pronounced increases in premature switching. Adding a discriminative stimulus when the response requirement was fulfilled increased the likelihood that a switch would occur only after the appropriate number of pecks had been emitted. It also attenuated the effects of the drugs. The presence of discriminative stimuli did not make as large a difference in performance in either of these experiments when chlorpromazine and promazine were studied. In general, work with other schedules of reinforcement supports the conclusion that behavior under strong external stimulus controls is less apt to be readily affected by many drugs. Addition of the discriminative stimulus can also ''improve'' the behavior of pigeons that have been given enouth methylmercury to increase greatly the variability of their performance. (auth)« less

Inhibitory Mechanisms in Primary Somatosensory Cortex Mediate the Effects of Peripheral Electrical Stimulation on Tactile Spatial Discrimination.

PubMed

Saito, Kei; Otsuru, Naofumi; Inukai, Yasuto; Kojima, Sho; Miyaguchi, Shota; Tsuiki, Shota; Sasaki, Ryoki; Onishi, Hideaki

2018-06-01

Selective afferent activation can be used to improve somatosensory function, possibly by altering cortical inhibitory circuit activity. Peripheral electrical stimulation (PES) is widely used to induce selective afferent activation, and its effect may depend on PES intensity. Therefore, we investigated the effects of high- and low-intensity PES applied to the right index finger on tactile discrimination performance and cortical sensory-evoked potential paired-pulse depression (SEP-PPD) in 25 neurologically healthy subjects. In Experiment 1, a grating orientation task (GOT) was performed before and immediately after local high- and low-intensity PES (both delivered as 1-s, 20-Hz trains of 0.2-ms electrical pulses at 5-s intervals). In Experiment 2, PPD of SEP components N20/P25_SEP-PPD and N20_SEP-PPD, respectively, were assessed before and immediately after high- and low-intensity PES. Improved GOT discrimination performance after high-intensity PES (reduced discrimination threshold) was associated with lower baseline performance (higher baseline discrimination threshold). Subjects were classified into low and high (baseline) GOT performance groups. Improved GOT discrimination performance in the low GOT performance group was significantly associated with a greater N20_SEP-PPD decrease (weaker PPD). Subjects were also classified into GOT improvement and GOT decrement groups. High-intensity PES decreased N20_SEP-PPD in the GOT improvement group but increased N20_SEP-PPD in the GOT decrement group. Furthermore, a greater decrease in GOT discrimination threshold was significantly associated with a greater N20_SEP-PPD decrease in the GOT improvement group. These results suggest that high-intensity PES can improve sensory perception in subjects with low baseline function by modulating cortical inhibitory circuits in primary somatosensory cortex. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Perceived weight discrimination in England: a population-based study of adults aged ⩾50 years

PubMed Central

Jackson, S E; Steptoe, A; Beeken, R J; Croker, H; Wardle, J

2015-01-01

Background: Despite a wealth of experimental studies on weight bias, little is known about weight discrimination at the population level. This study examined the prevalence and socio-demographic correlates of perceived weight discrimination in a large population-based sample of older adults. Methods: Data were from 5307 adults in the English Longitudinal Study of Ageing; a population-based cohort of men and women aged ⩾50 years. Weight discrimination was reported for five domains (less respect/courtesy; treated as less clever; poorer treatment in medical settings; poorer service in restaurants/stores; threatened/harassed) at wave 5 (2010–2011). Height and weight were measured at wave 4 (2008–2009). We used logistic regression to test the odds of weight discrimination in relation to weight status, age, sex, wealth, education and marital status. Results: Perceived weight discrimination in any domain was reported by 4.6% of participants, ranging from 0.8% in the normal-weight participants through 0.9, 6.7, 24.2 and 35.1% in individuals who were overweight or met criteria for class I, II and III obesity. Overall, and in each situation, odds of perceived weight discrimination were higher in younger and less wealthy individuals. There was no interaction between weight status and any socio-demographic variable. Relative to normal-weight participants, odds ratios for any perceived weight discrimination were 1.13 (95% confidence interval 0.53–2.40) in those who were overweight, 8.86 (4.65–16.88) in those with class I obesity, 35.06 (18.30–67.16) in class II obese and 56.43 (27.72–114.87) in class III obese. Conclusions: Our results indicate that rates of perceived weight discrimination are comparatively low in individuals who are overweight or have class I obesity, but for those with class II/III obesity, >10% had experienced discrimination in each domain, and >20% had been treated with less respect or courtesy. These findings have implications for public policy and highlight the need for effective interventions to promote equality. PMID:25327975

Perceived weight discrimination in England: a population-based study of adults aged ⩾50 years.

PubMed

Jackson, S E; Steptoe, A; Beeken, R J; Croker, H; Wardle, J

2015-05-01

Despite a wealth of experimental studies on weight bias, little is known about weight discrimination at the population level. This study examined the prevalence and socio-demographic correlates of perceived weight discrimination in a large population-based sample of older adults. Data were from 5307 adults in the English Longitudinal Study of Ageing; a population-based cohort of men and women aged ⩾50 years. Weight discrimination was reported for five domains (less respect/courtesy; treated as less clever; poorer treatment in medical settings; poorer service in restaurants/stores; threatened/harassed) at wave 5 (2010-2011). Height and weight were measured at wave 4 (2008-2009). We used logistic regression to test the odds of weight discrimination in relation to weight status, age, sex, wealth, education and marital status. Perceived weight discrimination in any domain was reported by 4.6% of participants, ranging from 0.8% in the normal-weight participants through 0.9, 6.7, 24.2 and 35.1% in individuals who were overweight or met criteria for class I, II and III obesity. Overall, and in each situation, odds of perceived weight discrimination were higher in younger and less wealthy individuals. There was no interaction between weight status and any socio-demographic variable. Relative to normal-weight participants, odds ratios for any perceived weight discrimination were 1.13 (95% confidence interval 0.53-2.40) in those who were overweight, 8.86 (4.65-16.88) in those with class I obesity, 35.06 (18.30-67.16) in class II obese and 56.43 (27.72-114.87) in class III obese. Our results indicate that rates of perceived weight discrimination are comparatively low in individuals who are overweight or have class I obesity, but for those with class II/III obesity, >10% had experienced discrimination in each domain, and >20% had been treated with less respect or courtesy. These findings have implications for public policy and highlight the need for effective interventions to promote equality.

Neural Substrates of View-Invariant Object Recognition Developed without Experiencing Rotations of the Objects

PubMed Central

Okamura, Jun-ya; Yamaguchi, Reona; Honda, Kazunari; Tanaka, Keiji

2014-01-01

One fails to recognize an unfamiliar object across changes in viewing angle when it must be discriminated from similar distractor objects. View-invariant recognition gradually develops as the viewer repeatedly sees the objects in rotation. It is assumed that different views of each object are associated with one another while their successive appearance is experienced in rotation. However, natural experience of objects also contains ample opportunities to discriminate among objects at each of the multiple viewing angles. Our previous behavioral experiments showed that after experiencing a new set of object stimuli during a task that required only discrimination at each of four viewing angles at 30° intervals, monkeys could recognize the objects across changes in viewing angle up to 60°. By recording activities of neurons from the inferotemporal cortex after various types of preparatory experience, we here found a possible neural substrate for the monkeys' performance. For object sets that the monkeys had experienced during the task that required only discrimination at each of four viewing angles, many inferotemporal neurons showed object selectivity covering multiple views. The degree of view generalization found for these object sets was similar to that found for stimulus sets with which the monkeys had been trained to conduct view-invariant recognition. These results suggest that the experience of discriminating new objects in each of several viewing angles develops the partially view-generalized object selectivity distributed over many neurons in the inferotemporal cortex, which in turn bases the monkeys' emergent capability to discriminate the objects across changes in viewing angle. PMID:25378169

Young Women do it Better: Sexual Dimorphism in Temporal Discrimination

PubMed Central

Williams, Laura Jane; Butler, John S.; Molloy, Anna; McGovern, Eavan; Beiser, Ines; Kimmich, Okka; Quinlivan, Brendan; O’Riordan, Sean; Hutchinson, Michael; Reilly, Richard B.

2015-01-01

The temporal discrimination threshold (TDT) is the shortest time interval at which two sensory stimuli presented sequentially are detected as asynchronous by the observer. TDTs are known to increase with age. Having previously observed shorter thresholds in young women than in men, in this work we sought to systematically examine the effect of sex and age on temporal discrimination. The aims of this study were to examine, in a large group of men and women aged 20–65 years, the distribution of TDTs with an analysis of the individual participant’s responses, assessing the “point of subjective equality” and the “just noticeable difference” (JND). These respectively assess sensitivity and accuracy of an individual’s response. In 175 participants (88 women) aged 20–65 years, temporal discrimination was faster in women than in men under the age of 40 years by a mean of approximately 13 ms. However, age-related decline in temporal discrimination was three times faster in women so that, in the age group of 40–65 years, the female superiority was reversed. The point of subjective equality showed a similar advantage in younger women and more marked age-related decline in women than men, as the TDT. JND values declined equally in both sexes, showing no sexual dimorphism. This observed sexual dimorphism in temporal discrimination is important for both (a) future clinical research assessing disordered mid-brain covert attention in basal-ganglia disorders, and (b) understanding the biology of this sexual dimorphism which may be genetic or hormonal. PMID:26217303

Temporal Integration of Auditory Information Is Invariant to Temporal Grouping Cues

PubMed

Liu, Andrew S K; Tsunada, Joji; Gold, Joshua I; Cohen, Yale E

2015-01-01

Auditory perception depends on the temporal structure of incoming acoustic stimuli. Here, we examined whether a temporal manipulation that affects the perceptual grouping also affects the time dependence of decisions regarding those stimuli. We designed a novel discrimination task that required human listeners to decide whether a sequence of tone bursts was increasing or decreasing in frequency. We manipulated temporal perceptual-grouping cues by changing the time interval between the tone bursts, which led to listeners hearing the sequences as a single sound for short intervals or discrete sounds for longer intervals. Despite these strong perceptual differences, this manipulation did not affect the efficiency of how auditory information was integrated over time to form a decision. Instead, the grouping manipulation affected subjects' speed-accuracy trade-offs. These results indicate that the temporal dynamics of evidence accumulation for auditory perceptual decisions can be invariant to manipulations that affect the perceptual grouping of the evidence.

A long-range and long-life telemetry data-acquisition system for heart rate and multiple body temperatures from free-ranging animals

NASA Technical Reports Server (NTRS)

Lund, G. F.; Westbrook, R. M.; Fryer, T. B.; Miranda, R. F.

1979-01-01

The system includes an implantable transmitter, external receiver-retransmitter collar, and a microprocessor-controlled demodulator. The size of the implant is suitable for animals with body weights of a few kilograms or more; further size reduction of the implant is possible. The ECG is sensed by electrodes designed for internal telemetry and to reduce movement artifacts. The R-wave characteristics are then specifically selected to trigger a short radio frequency pulse. Temperatures are sensed at desired locations by thermistors and then, based on a heartbeat counter, transmitted intermittently via pulse interval modulation. This modulation scheme includes first and last calibration intervals for a reference by ratios with the temperature intervals to achieve good accuracy even over long periods. Pulse duration and pulse sequencing are used to discriminate between heart rate and temperature pulses as well as RF interference.

The effect of age on the discriminative stimulus effects of ethanol and its GABA(A) receptor mediation in cynomolgus monkeys.

PubMed

Helms, Christa M; Grant, Kathleen A

2011-08-01

Excessive alcohol consumption is less common among aged compared to young adults, with aged adults showing greater sensitivity to many behavioral effects of ethanol. This study compared the discriminative stimulus effects of ethanol in young and middle-aged adult cynomolgus monkeys (Macaca fascicularis) and its γ-aminobutyric acid (GABA)(A) receptor mediation. Two male and two female monkeys trained to discriminate ethanol (1.0 g/kg, i.g.; 60-min pre-treatment interval) from water at 5-6 years of age (Grant et al. in Psychopharmacology 152:181-188, 2000) were re-trained in the current study more than a decade later (19.3 ± 1.0 years of age) for a within-subjects comparison. Also, four experimentally naïve middle-aged (mean ± SEM, 17.0 ± 1.5 years of age) female monkeys were trained to discriminate ethanol for between-subjects comparison with published data from young adult naïve monkeys. Two of the naïve middle-aged monkeys attained criterion performance, with weak stimulus control and few discrimination tests, despite greater blood-ethanol concentration 60 min after 1.0 g/kg ethanol in middle-aged compared to young adult female monkeys (Green et al. in Alcohol Clin Exp Res 23:611-616, 1999). The efficacy of the GABA(A) receptor positive modulators pentobarbital, midazolam, allopregnanolone, pregnanolone, and androsterone to substitute for the discriminative stimulus effects of 1.0 g/kg ethanol was maintained from young adulthood to middle age. The data suggest that 1.0 g/kg ethanol is a weak discriminative stimulus in naive middle-aged monkeys. Nevertheless, the GABA(A) receptor mechanisms mediating the discriminative stimulus effects of ethanol, when learned as a young adult, appear stable across one third of the primate lifespan.

Racial discrimination & cardiovascular disease risk: my body my story study of 1005 US-born black and white community health center participants (US).

PubMed

Krieger, Nancy; Waterman, Pamela D; Kosheleva, Anna; Chen, Jarvis T; Smith, Kevin W; Carney, Dana R; Bennett, Gary G; Williams, David R; Thornhill, Gisele; Freeman, Elmer R

2013-01-01

To date, limited and inconsistent evidence exists regarding racial discrimination and risk of cardiovascular disease (CVD). Cross-sectional observational study of 1005 US-born non-Hispanic black (n = 504) and white (n = 501) participants age 35-64 randomly selected from community health centers in Boston, MA (2008-2010; 82.4% response rate), using 3 racial discrimination measures: explicit self-report; implicit association test (IAT, a time reaction test for self and group as target vs. perpetrator of discrimination); and structural (Jim Crow status of state of birth, i.e. legal racial discrimination prior 1964). Black and white participants both had adverse cardiovascular and socioeconomic profiles, with black participants most highly exposed to racial discrimination. Positive crude associations among black participants occurred for Jim Crow birthplace and hypertension (odds ratio (OR) 1.92, 95% confidence interval (CI) 1.28, 2.89) and for explicit self-report and the Framingham 10 year CVD risk score (beta = 0.04; 95% CI 0.01, 0.07); among white participants, only negative crude associations existed (for IAT for self, for lower systolic blood pressure (SBP; beta = -4.86; 95% CI -9.08, -0.64) and lower Framingham CVD score (beta = -0.36, 95% CI -0.63, -0.08)). All of these associations were attenuated and all but the white IAT-Framingham risk score association were rendered null in analyses that controlled for lifetime socioeconomic position and additional covariates. Controlling for racial discrimination, socioeconomic position, and other covariates did not attenuate the crude black excess risk for SBP and hypertension and left unaffected the null excess risk for the Framingham CVD score. Despite worse exposures among the black participants, racial discrimination and socioeconomic position were not associated, in multivariable analyses, with risk of CVD. We interpret results in relation to constrained variability of exposures and outcomes and discuss implications for valid research on social determinants of health.

Out of sight but not out of mind: the neurophysiology of iconic memory in the superior temporal sulcus.

PubMed

Keysers, C; Xiao, D-K; Foldiak, P; Perrett, D I

2005-05-01

Iconic memory, the short-lasting visual memory of a briefly flashed stimulus, is an important component of most models of visual perception. Here we investigate what physiological mechanisms underlie this capacity by showing rapid serial visual presentation (RSVP) sequences with and without interstimulus gaps to human observers and macaque monkeys. For gaps of up to 93 ms between consecutive images, human observers and neurones in the temporal cortex of macaque monkeys were found to continue processing a stimulus as if it was still present on the screen. The continued firing of neurones in temporal cortex may therefore underlie iconic memory. Based on these findings, a neurophysiological vision of iconic memory is presented.

Orbital stability of solitary waves for generalized Boussinesq equation with two nonlinear terms

NASA Astrophysics Data System (ADS)

Zhang, Weiguo; Li, Xiang; Li, Shaowei; Chen, Xu

2018-06-01

This paper investigates the orbital stability and instability of solitary waves for the generalized Boussinesq equation with two nonlinear terms. Firstly, according to the theory of Grillakis-Shatah-Strauss orbital stability, we present the general results to judge orbital stability of the solitary waves. Further, we deduce the explicit expression of discrimination d‧‧(c) to judge the stability of the two solitary waves, and give the stable wave speed interval. Moreover, we analyze the influence of the interaction between two nonlinear terms on the stable wave speed interval, and give the maximal stable range for the wave speed. Finally, some conclusions are given in this paper.

Musical training generalises across modalities and reveals efficient and adaptive mechanisms for reproducing temporal intervals.

PubMed

Aagten-Murphy, David; Cappagli, Giulia; Burr, David

2014-03-01

Expert musicians are able to time their actions accurately and consistently during a musical performance. We investigated how musical expertise influences the ability to reproduce auditory intervals and how this generalises across different techniques and sensory modalities. We first compared various reproduction strategies and interval length, to examine the effects in general and to optimise experimental conditions for testing the effect of music, and found that the effects were robust and consistent across different paradigms. Focussing on a 'ready-set-go' paradigm subjects reproduced time intervals drawn from distributions varying in total length (176, 352 or 704 ms) or in the number of discrete intervals within the total length (3, 5, 11 or 21 discrete intervals). Overall, Musicians performed more veridical than Non-Musicians, and all subjects reproduced auditory-defined intervals more accurately than visually-defined intervals. However, Non-Musicians, particularly with visual stimuli, consistently exhibited a substantial and systematic regression towards the mean interval. When subjects judged intervals from distributions of longer total length they tended to regress more towards the mean, while the ability to discriminate between discrete intervals within the distribution had little influence on subject error. These results are consistent with a Bayesian model that minimizes reproduction errors by incorporating a central tendency prior weighted by the subject's own temporal precision relative to the current distribution of intervals. Finally a strong correlation was observed between all durations of formal musical training and total reproduction errors in both modalities (accounting for 30% of the variance). Taken together these results demonstrate that formal musical training improves temporal reproduction, and that this improvement transfers from audition to vision. They further demonstrate the flexibility of sensorimotor mechanisms in adapting to different task conditions to minimise temporal estimation errors. © 2013.

Investigations of timing during the schedule and reinforcement intervals with wheel-running reinforcement.

PubMed

Belke, Terry W; Christie-Fougere, Melissa M

2006-11-01

Across two experiments, a peak procedure was used to assess the timing of the onset and offset of an opportunity to run as a reinforcer. The first experiment investigated the effect of reinforcer duration on temporal discrimination of the onset of the reinforcement interval. Three male Wistar rats were exposed to fixed-interval (FI) 30-s schedules of wheel-running reinforcement and the duration of the opportunity to run was varied across values of 15, 30, and 60s. Each session consisted of 50 reinforcers and 10 probe trials. Results showed that as reinforcer duration increased, the percentage of postreinforcement pauses longer than the 30-s schedule interval increased. On probe trials, peak response rates occurred near the time of reinforcer delivery and peak times varied with reinforcer duration. In a second experiment, seven female Long-Evans rats were exposed to FI 30-s schedules leading to 30-s opportunities to run. Timing of the onset and offset of the reinforcement period was assessed by probe trials during the schedule interval and during the reinforcement interval in separate conditions. The results provided evidence of timing of the onset, but not the offset of the wheel-running reinforcement period. Further research is required to assess if timing occurs during a wheel-running reinforcement period.