Temporal Response Patterns Research Articles

Utilizing the response patterns of a temperature modulated chemoresistive gas sensor for gas diagnosis

The observed features in the temporal response patterns of a temperature-modulated chemoresistive gas sensor were used for gas diagnosis. The patterns were recorded for clean air and air contaminated with different levels of some volatile organic compounds while a staircase heating voltage waveform had been applied to the microheater of a tin oxide gas sensor that modulated its operating temperature. Combining the steady-state and transient parameters of the recorded responses in the 50–400°C range resulted in discriminatory feature vectors which were utilized for contaminant classification. The information content of these feature vectors was proved sufficient for discrimination of methanol, ethanol, 1-butanol, and acetone contaminations in a wide concentration range.

Decoupling spatial and temporal patterns in short-term beach shoreline response to wave climate

This paper describes the use of a combined approach which merges numerical models and remote video techniques to derive the spatial and temporal patterns in short-term beach shoreline forcing-response to wave climate on a microtidal low energy sandy beach. Shorelines are obtained after applying an Artificial Neural Network (ANN) to daily raw video images. The data comprise directional hydrodynamic conditions propagated from deep water to 10 m depth and video-derived daily shorelines over the span of one year and a half. The spatial and temporal variability of the beach is split by Empirical Orthogonal Function (EOF) decomposition. Time-series exploration between EOF and wave height shows a decoupling in spatial shoreline response to wave climate with a more immediate effect in cross-shore sediment transport than in alongshore sediment transport. The first EOF which accounts for the cross-shore variability is significantly correlated with wave height averaged for the previous four days, while the second EOF which explains the alongshore beach variability correlates with the averaged waves of the previous 7 days.

Segmental patterns of vestibular-mediated synaptic inputs to axial and limb motoneurons in the neonatal mouse assessed by optical recording

Proper control of movement and posture occurs partly via descending projections from the vestibular nuclei to spinal motor circuits. Days before birth in rodents, vestibulospinal neurons develop axonal projections that extend to the spinal cord. How functional these projections are just after birth is unknown. Our goal was to assess the overall functional organization of vestibulospinal inputs to spinal motoneurons in a brainstem-spinal cord preparation of the neonatal mouse (postnatal day (P) 0-5). Using calcium imaging, we recorded responses evoked by electrical stimulation of the VIIIth nerve, in many motoneurons simultaneously throughout the spinal cord (C2, C6, T7, L2 and L5 segments), in the medial and lateral motor columns. Selective lesions in the brainstem and/or spinal cord distinguished which tracts contributed to the responses: those in the cervical cord originated primarily from the medial vestibulospinal tracts but with a substantial contribution from the lateral vestibulospinal tract; those in the thoracolumbar cord originated exclusively from the lateral vestibulospinal tract. In the thoracolumbar but not the cervical cord, excitatory commissural connections mediated vestibular responses in contralateral motoneurons. Pharmacological blockade of GABA(A) receptors showed that responses involved a convergence of excitatory and inhibitory inputs which in combination produced temporal response patterns specific for different segmental levels. Our results show that by birth vestibulospinal projections in rodents have already established functional synapses and are organized to differentially regulate activity in neck and limb motoneurons in a tract- and segment-specific pattern similar to that in adult mammals. Thus, this particular set of descending projections develops several key features of connectivity appropriately at prenatal stages. We also present novel information about vestibulospinal inputs to axial motoneurons in mammals, providing a more comprehensive platform for future studies into the overall organization of vestibulospinal inputs and their role in regulating postural stability.

Neural Correlates of Auditory Streaming of Harmonic Complex Sounds With Different Phase Relations in the Songbird Forebrain

It has been suggested that successively presented sounds that are perceived as separate auditory streams are represented by separate populations of neurons. Mostly, spectral separation in different peripheral filters has been identified as the cue for segregation. However, stream segregation based on temporal cues is also possible without spectral separation. Here we present sequences of ABA- triplet stimuli providing only temporal cues to neurons in the European starling auditory forebrain. A and B sounds (125 ms duration) were harmonic complexes (fundamentals 100, 200, or 400 Hz; center frequency and bandwidth chosen to fit the neurons' tuning characteristic) with identical amplitude spectra but different phase relations between components (cosine, alternating, or random phase) and presented at different rates. Differences in both rate responses and temporal response patterns of the neurons when stimulated with harmonic complexes with different phase relations provide first evidence for a mechanism allowing a separate neural representation of such stimuli. Recording sites responding >1 kHz showed enhanced rate and temporal differences compared with those responding at lower frequencies. These results demonstrate a neural correlate of streaming by temporal cues due to the variation of phase that shows striking parallels to observations in previous psychophysical studies.

Neural correlates of own- and other-race face perception: Spatial and temporal response differences

Humans show an “other-race effect” for face recognition, with more accurate recognition of own- versus other-race faces. We compared the neural representations of own- and other-race faces using functional magnetic resonance imaging (fMRI) data in combination with a multi-voxel pattern classifier. Neural activity was recorded while Asians and Caucasians viewed Asian and Caucasian faces. A pattern classifier, applied to voxels across a broad range of ventral temporal areas, discriminated the brain activity maps elicited in response to Asian versus Caucasian faces in the brains of both Asians and Caucasians. Classification was most accurate in the first few time points of the block and required the use of own-race faces in the localizer scan to select voxels for classifier input. Next, we examined differences in the time-course of neural responses to own- and other-race faces and found evidence for a temporal “other-race effect.” Own-race faces elicited a larger neural response initially that attenuated rapidly. The response to other-race faces was weaker at first, but increased over time, ultimately surpassing the magnitude of the own-race response in the fusiform “face” area (FFA). A similar temporal response pattern held across a broad range of ventral temporal areas. The pattern-classification results indicate the early availability of categorical information about own- versus other-race face status in the spatial pattern of neural activity. The slower, more sustained, brain response to other-race faces may indicate the need to recruit additional neural resources to process other-race faces for identification.

Changes in skeletal muscle qualities during enzyme replacement therapy in late‐onset type II glycogenosis: temporal and spatial pattern of mass vs. strength response

Muscle quality is defined as muscle strength generated per unit muscle mass. If enzyme replacement therapy (ERT) has some effects on type II glycogenosis (GSDII) skeletal muscle pathology, we should be able to measure a change in strength and mass. We conducted a prospective study including 11 patients aged 54.2 ± 11.2 years, referring to a single institution and receiving ERT for ≥2 years. Median Walton score was 3 (2.5-6). Lower limb skeletal muscles were assessed by dynamometry and quantitative muscle MRI. Three segments (anterior thigh, posterior thigh, leg) were analysed separately. Clinical-MRI correlations were searched for at T0, T6/T8, and T18/24. Changes in lean and fat body composition were assessed by bioelectrical impedance analysis. We found that the anterior thigh showed the best therapeutic response, with an improvement in muscle quality (muscle mass: +7.5%, p = 0.035; strength: +45%, p = 0.002). BMI and lean body mass increased (p = 0.007). Patients with low BMI showed a better outcome. Intramuscular fat accumulation significantly progressed in spite of ERT (+3.7%, p = 0.001), especially in the poorly responsive posterior thigh muscles. Both clinical assessment and MRI revealed a definite improvement in the anterior thigh muscles. However, progression of intramuscular fat accumulation during ERT, as well as the limited responsiveness of posterior thigh muscles, suggests the necessity for early treatment intervention. The better outcome of patients with low BMI, if confirmed, may indicate that dietary protocols could be adopted as adjuvant measures to ERT in adult GSDII.

Neural Correlates of Auditory Scene Analysis Based on Inharmonicity in Monkey Primary Auditory Cortex

Segregation of concurrent sounds in complex acoustic environments is a fundamental feature of auditory scene analysis. A powerful cue used by the auditory system to segregate concurrent sounds, such as speakers' voices at a cocktail party, is inharmonicity. This can be demonstrated when a component of a harmonic complex tone is perceived as a separate tone "popping out" from the complex as a whole when it is sufficiently mistuned from its harmonic value. The neural bases of perceptual "pop out" of mistuned harmonics are unclear. We recorded multiunit activity from primary auditory cortex (A1) of behaving monkeys elicited by harmonic complex tones that were either "in tune" or that contained a mistuned third harmonic set at the best frequency of the neural populations. Responses to mistuned sounds were enhanced relative to responses to "in-tune" sounds, thus correlating with the enhanced perceptual salience of the mistuned component. Consistent with human psychophysics of "pop out," response enhancements increased with the degree of mistuning, were maximal for neural populations tuned to the frequency of the mistuned component, and were not observed under comparable stimulus conditions that do not elicit perceptual "pop out." Mistuning was also associated with changes in neuronal temporal response patterns phase locked to "beats" in the stimuli. Intracortical auditory evoked potentials paralleled noninvasive neurophysiological correlates of perceptual "pop out" in humans, further augmenting the translational relevance of the results. Findings suggest two complementary neural mechanisms for "pop out," based on the detection of local differences in activation level or coherence of temporal response patterns across A1.

Fluidity of HIV-1-Specific T-Cell Responses during Acute and Early Subtype C HIV-1 Infection and Associations with Early Disease Progression

Deciphering immune events during early stages of human immunodeficiency virus type 1 (HIV-1) infection is critical for understanding the course of disease. We characterized the hierarchy of HIV-1-specific T-cell gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay responses during acute subtype C infection in 53 individuals and associated temporal patterns of responses with disease progression in the first 12 months. There was a diverse pattern of T-cell recognition across the proteome, with the recognition of Nef being immunodominant as early as 3 weeks postinfection. Over the first 6 months, we found that there was a 23% chance of an increased response to Nef for every week postinfection (P = 0.0024), followed by a nonsignificant increase to Pol (4.6%) and Gag (3.2%). Responses to Env and regulatory proteins appeared to remain stable. Three temporal patterns of HIV-specific T-cell responses could be distinguished: persistent, lost, or new. The proportion of persistent T-cell responses was significantly lower (P = 0.0037) in individuals defined as rapid progressors than in those progressing slowly and who controlled viremia. Almost 90% of lost T-cell responses were coincidental with autologous viral epitope escape. Regression analysis between the time to fixed viral escape and lost T-cell responses (r = 0.61; P = 0.019) showed a mean delay of 14 weeks after viral escape. Collectively, T-cell epitope recognition is not a static event, and temporal patterns of IFN-γ-based responses exist. This is due partly to viral sequence variation but also to the recognition of invariant viral epitopes that leads to waves of persistent T-cell immunity, which appears to associate with slower disease progression in the first year of infection.

Differential spatial and temporal neural response patterns for own- and other-race faces

 neural response to Asian and Caucasian faces discriminable with pattern classification methods  high-level visual and face-selective areas in VT cortex  importance of own-race face localizer  time-course differences in neural activation for own-race vs. other-race efficient own-race face processing  dedication of additional resources for other-race face processing  use of areas beyond the FFA for categorization of faces by race PATTERN-BASED CLASSIFICATION

Slope-Based Stochastic Resonance: How Noise Enables Phasic Neurons to Encode Slow Signals

Fundamental properties of phasic firing neurons are usually characterized in a noise-free condition. In the absence of noise, phasic neurons exhibit Class 3 excitability, which is a lack of repetitive firing to steady current injections. For time-varying inputs, phasic neurons are band-pass filters or slope detectors, because they do not respond to inputs containing exclusively low frequencies or shallow slopes. However, we show that in noisy conditions, response properties of phasic neuron models are distinctly altered. Noise enables a phasic model to encode low-frequency inputs that are outside of the response range of the associated deterministic model. Interestingly, this seemingly stochastic-resonance (SR) like effect differs significantly from the classical SR behavior of spiking systems in both the signal-to-noise ratio and the temporal response pattern. Instead of being most sensitive to the peak of a subthreshold signal, as is typical in a classical SR system, phasic models are most sensitive to the signal's rising and falling phases where the slopes are steep. This finding is consistent with the fact that there is not an absolute input threshold in terms of amplitude; rather, a response threshold is more properly defined as a stimulus slope/frequency. We call the encoding of low-frequency signals with noise by phasic models a slope-based SR, because noise can lower or diminish the slope threshold for ramp stimuli. We demonstrate here similar behaviors in three mechanistic models with Class 3 excitability in the presence of slow-varying noise and we suggest that the slope-based SR is a fundamental behavior associated with general phasic properties rather than with a particular biological mechanism.

Structural and functional shifts in zoobenthos induced by organic enrichment — Implications for community recovery potential

Habitat change induced by organic enrichment is a growing concern for the sustainability of benthic communities in coastal aquatic environments. This case study describes the spatial and temporal response patterns and the recovery potential of low-diversity benthic communities to organic enrichment at two fish farm locations, during the rearing periods (15 and 20 years, respectively) and the following recovery periods (2 years). The spatial extent of disturbance differed depending on the hydromorphological characteristics of the rearing sites, but degraded macrobenthic communities close to both fish farms were recorded soon after the activity started. Continued organic enrichment resulted in high species turnover-rates and in an altered benthic community composition at both locations. After fish farm abatement, a partial recovery was detected in species richness, but abundance and biomass values were reduced and changes in structural composition remained. Alterations in benthic biological traits were observed at both fish farm locations, implying that organic enrichment might cause changes in benthic community function within low-diversity benthic communities.

TEMPORAL PATTERNS OF BEHAVIOR FROM THE SCHEDULING OF PSYCHOLOGY QUIZZES

Temporal patterns of behavior have been observed in real-life performances such as bill passing in the U.S. Congress, in-class studying, and quiz taking. However, the practical utility of understanding these patterns has not been evaluated. The current study demonstrated the presence of temporal patterns of quiz taking in a university-level introductory psychology course and used these patterns to manage the traffic of quiz takers in a computerized testing lab. Results are discussed in terms of the applications of tracking temporal response patterns.

Temporal patterns in the transcriptomic response of rainbow trout, Oncorhynchus mykiss, to crude oil

Time is often not characterized as a variable in ecotoxicogenomic studies. In this study, temporal changes in gene expression were determined during exposure to crude oil and a subsequent recovery period. Juvenile rainbow trout, Oncorhynchus mykiss, were exposed for 96 h to the water accommodated fractions of 0.4, 2 or 10 mg l −1 crude oil loadings. Following 96 h of exposure, fish were transferred to recovery tanks. Gill and liver samples were collected after 24 and 96 h of exposure, and after 96 h of recovery for RNA extraction and microarray analysis. Fluorescently labeled cDNA was hybridized against matched controls, using salmonid cDNA arrays. Each exposure scenario generated unique patterns of altered gene expression. More genes responded to crude oil in the gill than in the liver. In the gill, 1137 genes had altered expression at 24 h, 2003 genes had altered expression levels at 96 h of exposure, yet by 96 h of recovery, no genes were significantly altered in expression. In the liver at 10 mg l −1, only five genes were changed at 24 h, yet 192 genes had altered expression after 96 h recovery. At 2 mg l −1 in the liver, many genes had altered regulation at all three time points. The 0.4 mg l −1 loading also showed 289 genes upregulated at 24 h after exposure. The Gene Ontology terms associated with altered expression in the liver suggested that the processes of protein synthesis, xenobiotic metabolism, and oxidoreductase activity were altered. The concentration-responsive expression profile of cytochrome P450 1A, a biomarker for oil exposure, did not predict the majority of gene expression profiles in any tissue or dose, since direct relationships with dose were not observed for most genes. While the genes and their associated functions agree with known modes of toxic action for crude oil, the gene lists obtained do not match our previously published work, presumably due to array analysis procedures. These results demonstrate that changes in gene expression with time and dose may be complicated, and should be characterized in controlled laboratory settings before attempts are made to interpret responses in field-collected organisms. Further, processes for analyzing microarray data need to be developed such that standardized gene lists are developed, or that analysis does not rely on lists of significantly altered genes before arrays can be further evaluated as a monitoring tool.

Long-term trophic evolution of a northern reservoir following impoundment: different temporal response patterns of primary production and plankton biomass with a predictive model for future trends

(2010). Long-term trophic evolution of a northern reservoir following impoundment: different temporal response patterns of primary production and plankton biomass with a predictive model for future trends. SIL Proceedings, 1922-2010: Vol. 30, No. 10, pp. 1619-1624.

Blood Gene Expression Signatures Predict Invasive Candidiasis

Candidemia is the fourth most common bloodstream infection, with Candida albicans being the most common causative species. Success in reducing the associated morbidity and mortality has been limited by the inadequacy and time delay of currently available diagnostic modalities. Focusing on host response to infection, we used a murine model to develop a blood gene expression signature that accurately classified mice with candidemia and distinguished candidemia from Staphylococcus aureus bacteremia. Validation of the signature was achieved in an independent cohort of mice. Genes represented in the signature have known associations with host defense against Candida and other microorganisms. Our results demonstrate a temporal pattern of host molecular responses that distinguish candidemia from S. aureus-induced bacteremia and establish a novel paradigm for infectious disease diagnosis.

The upper limit of temporal pitch for cochlear-implant listeners: Stimulus duration, conditioner pulses, and the number of electrodes stimulated

Three experiments studied discrimination of changes in the rate of electrical pulse trains by cochlear-implant (CI) users and investigated the effect of manipulations that would be expected to substantially affect the pattern of auditory nerve (AN) activity. Experiment 1 used single-electrode stimulation and tested discrimination at baseline rates between 100 and 500 pps. Performance was generally similar for stimulus durations of 200 and 800 ms, and, for the longer duration, for stimuli that were gated on abruptly or with 300-ms ramps. Experiment 2 used a similar procedure and found that no substantial benefit was obtained by the addition of background 5000-pps "conditioning" pulses. Experiment 3 used a pitch-ranking procedure and found that the range of rates over which pitch increased with increasing rate was not greater for multiple-electrode than for single-electrode stimulation. The results indicate that the limitation on pulse-rate discrimination by CI users, at high baseline rates, is not specific to a particular temporal pattern of the AN response.

Preceding Inhibition Silences Layer 6 Neurons in Auditory Cortex

A canonical feedforward circuit is proposed to underlie sensory cortical responses with balanced excitation and inhibition in layer 4 (L4). However, in another input layer, L6, sensory responses and the underlying synaptic circuits remain largely unclear. Here, cell-attached recordings in rat primary auditory cortex revealed that for the majority of L6 excitatory neurons, tonal stimuli did not drive spike responses, but suppressed spontaneous firings. Whole-cell recordings further revealed that the silencing resulted from tone-evoked strong inhibition arriving earlier than excitation. This pattern of inputs can be attributed to a parallel feedforward circuit with both excitatory and inhibitory inputs disynaptically relayed. In contrast, in the other neurons directly driven by thalamic input, stimuli evoked excitation preceding relatively weak inhibition, resulting in robust spike responses. Thus, the dichotomy of L6 response properties arises from two distinct patterns of excitatory-inhibitory interplay. The parallel circuit module generating preceding inhibition may provide a gating mechanism for conditional corticothalamic feedback.

The projective field of single bipolar cells in the retina

Event Abstract Back to Event The projective field of single bipolar cells in the retina Hiroki Asari1* and Markus Meister2 1 Harvard University, Department of Molecular and Cellular Biology, United States 2 Harvard University, United States The vertebrate retina contains about 10 types of bipolar cells that convey information from photoreceptors to retinal ganglion cells. Previous studies suggest that they form parallel channels, and that each bipolar cell type contributes a specific visual message to select types of ganglion cells. Here we test this hypothesis by determining the full projective field of a single bipolar cell, specifically the responses it elicits in the population of ganglion cells. In the isolated salamander retina, we controlled bipolar cell activity with an intracellular electrode while recording the firing of ganglion cells with a multi-electrode array and manipulating the intervening circuitry pharmacologically. We found that excitation of a single bipolar cell altered the responses of many ganglion cells. The effect was generally excitatory at short distances and inhibitory at longer distances. Electrical synapses among bipolar cells contributed substantially to the lateral spread of excitation, whereas amacrine cells suppressed the excitatory spread and mediated the inhibitory effects. Within the excitatory region, different ganglion cells showed distinct temporal response patterns. A sustained depolarization of the bipolar cell produced a transient burst of spikes in some ganglion cells but sustained firing in others. This range of response kinetics resulted primarily from the interactions of individual bipolar cell terminals with amacrine cells. Our results highlight the diversity of neuronal circuits that distribute signals from a bipolar cell to various ganglion cells, and suggest considerable cross-talk between bipolar cell channels through gap junctions and via amacrine cells. Conference: Computational and Systems Neuroscience 2010, Salt Lake City, UT, United States, 25 Feb - 2 Mar, 2010. Presentation Type: Poster Presentation Topic: Poster session I Citation: Asari H and Meister M (2010). The projective field of single bipolar cells in the retina. Front. Neurosci. Conference Abstract: Computational and Systems Neuroscience 2010. doi: 10.3389/conf.fnins.2010.03.00145 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 02 Mar 2010; Published Online: 02 Mar 2010. * Correspondence: Hiroki Asari, Harvard University, Department of Molecular and Cellular Biology, Paris, United States, asari@fas.harvard.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Hiroki Asari Markus Meister Google Hiroki Asari Markus Meister Google Scholar Hiroki Asari Markus Meister PubMed Hiroki Asari Markus Meister Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The Temporal Pattern of Mortality Responses to Ambient Ozone in the Aphea Project

Background: The temporal pattern of effects of summertime ozone (O 3 ) in total, cardiovascular and respiratory mortality were investigated in 21 European cities participating in the APHEA-2 (Air Pollution and Health: a European Approach) project, which is fundamental in determining the importance of the effect in terms of life loss. Methods: Data from each city were analysed separately using distributed lag models with up to 21 lags. City-specific air pollution estimates were regressed on city-specific covariates to obtain overall estimates and to explore sources of possible heterogeneity. Results: Stronger effects on respiratory mortality that extend to a period of 2 weeks were found. A 10 μg/m 3 increase in O 3 was associated with a 0.36% (95% CI −0.21% to 0.94%) increase in respiratory deaths for lag 0 and with 3.35% (95% CI 1.90% to 4.83%) for lags 0–20. Significant adverse health effects were found of summer O 3 (June–August) on total and cardiovascular mortality that persist up to a week, but are counterbalanced by negative effects thereafter. Conclusions: The results indicate that studies on acute health effects of O 3 using single-day exposures may have overestimated the effects on total and cardiovascular mortality, but underestimated the effects on respiratory mortality.

Competitive anxiety and cortisol awakening response in the week leading up to a competition

Objectives This study investigated the psychological as well as neuroendocrine stress response across one week before an important sport competition, introducing the cortisol awakening response (CAR) to sport psychological research. Methods On three days in the week before the German Nationals, martial artists ( N = 17) reported their competitive state anxiety and collected five samples of salivary cortisol during the first hour after awakening. Results Hierarchic-linear models and multiple regressions were conducted. Despite a significant rise in “somatic anxiety” ( p < .05), the increment of CAR across the week remained non-significant. A moderator function of competitive anxiety on the released amount of cortisol in the morning was not found significant. Results did not show any significant regression of changes in the neuroendocrine response on changes in state anxiety. Conclusion Non-significant increments of CAR with a closer proximity to the competition may be interpreted as a possible habituation of basal hypothalamus-pituitary-adrenal activity. Moreover, athletes appear to have a lower CAR than found in norm studies, which points to further investigation of interindividual and situational effects on the temporal pattern of the neuroendocrine response to sport competitions.