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Sample records for reflex receptive fields

  1. A new objective method for acquisition and quantification of reflex receptive fields.

    PubMed

    Jensen, Michael Brun; Manresa, José Biurrun; Andersen, Ole Kæseler

    2015-03-01

    The nociceptive withdrawal reflex (NWR) is a polysynaptic spinal reflex correlated with pain perception. Assessment of this objective physiological measure constitutes the core of existing methods for quantification of reflex receptive fields (RRFs), which however still suffer from a certain degree of subjective involvement. This article proposes a strictly objective methodology for RRF quantification based on automated identification of NWR thresholds (NWR-Ts). Nociceptive withdrawal reflex thresholds were determined for 10 individual stimulation sites using an interleaved up-down staircase method. Reflexes were detected from electromyography by evaluation of interval peak z scores and application of conduction velocity analysis. Reflex receptive field areas were quantified from interpolated mappings of NWR-Ts and compared with existing RRF quantifications. A total of 3 repeated measures were performed in 2 different sessions to evaluate the test-retest reliability of the various quantifications, using coefficients of repeatability (CRs) and hypothetical sample sizes. The novel quantifications based on identification of NWR-Ts showed a similar level of reliability within and between sessions, whereas existing quantifications all demonstrated worse between-session than within-session reliability. The NWR-T-based quantifications required a smaller sample size than any of the existing RRF measures to detect a clinically relevant effect in a crossover study design involving more than 1 session. Of all measures, quantification from mapping of inversed NWR-Ts demonstrated superior reliability both within (CR, 0.25) and between sessions (CR, 0.28). The study presents a more reliable and robust quantification of the RRF to be used as biomarker of pain hypersensitivity in clinical and experimental research.

  2. Reflex receptive fields are enlarged in patients with musculoskeletal low back and neck pain.

    PubMed

    Biurrun Manresa, José A; Neziri, Alban Y; Curatolo, Michele; Arendt-Nielsen, Lars; Andersen, Ole K

    2013-08-01

    Pain hypersensitivity has been consistently detected in chronic pain conditions, but the underlying mechanisms are difficult to investigate in humans and thus poorly understood. Patients with endometriosis pain display enlarged reflex receptive fields (RRF), providing a new perspective in the identification of possible mechanisms behind hypersensitivity states in humans. The primary hypothesis of this study was that RRF are enlarged in patients with musculoskeletal pain. Secondary study end points were subjective pain thresholds and nociceptive withdrawal reflex (NWR) thresholds after single and repeated (temporal summation) electrical stimulation. Forty chronic neck pain patients, 40 chronic low back pain patients, and 24 acute low back pain patients were tested. Electrical stimuli were applied to 10 sites on the sole of the foot to quantify the RRF, defined as the area of the foot from where a reflex was evoked. For the secondary end points, electrical stimuli were applied to the cutaneous innervation area of the sural nerve. All patient groups presented enlarged RRF areas compared to pain-free volunteers (P<.001). Moreover, they also displayed lower NWR and pain thresholds to single and repeated electrical stimulation (P<.001). These results demonstrate that musculoskeletal pain conditions are characterized by enlarged RRF, lowered NWR and pain thresholds, and facilitated temporal summation, most likely caused by widespread spinal hyperexcitability. This study contributes to a better understanding of the mechanisms underlying these pain conditions, and it supports the use of the RRF and NWR as objective biomarkers for pain hypersensitivity in clinical and experimental pain research. PMID:23707309

  3. Central auditory neurons have composite receptive fields

    PubMed Central

    Kozlov, Andrei S.; Gentner, Timothy Q.

    2016-01-01

    High-level neurons processing complex, behaviorally relevant signals are sensitive to conjunctions of features. Characterizing the receptive fields of such neurons is difficult with standard statistical tools, however, and the principles governing their organization remain poorly understood. Here, we demonstrate multiple distinct receptive-field features in individual high-level auditory neurons in a songbird, European starling, in response to natural vocal signals (songs). We then show that receptive fields with similar characteristics can be reproduced by an unsupervised neural network trained to represent starling songs with a single learning rule that enforces sparseness and divisive normalization. We conclude that central auditory neurons have composite receptive fields that can arise through a combination of sparseness and normalization in neural circuits. Our results, along with descriptions of random, discontinuous receptive fields in the central olfactory neurons in mammals and insects, suggest general principles of neural computation across sensory systems and animal classes. PMID:26787894

  4. Idealized computational models for auditory receptive fields.

    PubMed

    Lindeberg, Tony; Friberg, Anders

    2015-01-01

    We present a theory by which idealized models of auditory receptive fields can be derived in a principled axiomatic manner, from a set of structural properties to (i) enable invariance of receptive field responses under natural sound transformations and (ii) ensure internal consistency between spectro-temporal receptive fields at different temporal and spectral scales. For defining a time-frequency transformation of a purely temporal sound signal, it is shown that the framework allows for a new way of deriving the Gabor and Gammatone filters as well as a novel family of generalized Gammatone filters, with additional degrees of freedom to obtain different trade-offs between the spectral selectivity and the temporal delay of time-causal temporal window functions. When applied to the definition of a second-layer of receptive fields from a spectrogram, it is shown that the framework leads to two canonical families of spectro-temporal receptive fields, in terms of spectro-temporal derivatives of either spectro-temporal Gaussian kernels for non-causal time or a cascade of time-causal first-order integrators over the temporal domain and a Gaussian filter over the logspectral domain. For each filter family, the spectro-temporal receptive fields can be either separable over the time-frequency domain or be adapted to local glissando transformations that represent variations in logarithmic frequencies over time. Within each domain of either non-causal or time-causal time, these receptive field families are derived by uniqueness from the assumptions. It is demonstrated how the presented framework allows for computation of basic auditory features for audio processing and that it leads to predictions about auditory receptive fields with good qualitative similarity to biological receptive fields measured in the inferior colliculus (ICC) and primary auditory cortex (A1) of mammals. PMID:25822973

  5. Idealized Computational Models for Auditory Receptive Fields

    PubMed Central

    Lindeberg, Tony; Friberg, Anders

    2015-01-01

    We present a theory by which idealized models of auditory receptive fields can be derived in a principled axiomatic manner, from a set of structural properties to (i) enable invariance of receptive field responses under natural sound transformations and (ii) ensure internal consistency between spectro-temporal receptive fields at different temporal and spectral scales. For defining a time-frequency transformation of a purely temporal sound signal, it is shown that the framework allows for a new way of deriving the Gabor and Gammatone filters as well as a novel family of generalized Gammatone filters, with additional degrees of freedom to obtain different trade-offs between the spectral selectivity and the temporal delay of time-causal temporal window functions. When applied to the definition of a second-layer of receptive fields from a spectrogram, it is shown that the framework leads to two canonical families of spectro-temporal receptive fields, in terms of spectro-temporal derivatives of either spectro-temporal Gaussian kernels for non-causal time or a cascade of time-causal first-order integrators over the temporal domain and a Gaussian filter over the logspectral domain. For each filter family, the spectro-temporal receptive fields can be either separable over the time-frequency domain or be adapted to local glissando transformations that represent variations in logarithmic frequencies over time. Within each domain of either non-causal or time-causal time, these receptive field families are derived by uniqueness from the assumptions. It is demonstrated how the presented framework allows for computation of basic auditory features for audio processing and that it leads to predictions about auditory receptive fields with good qualitative similarity to biological receptive fields measured in the inferior colliculus (ICC) and primary auditory cortex (A1) of mammals. PMID:25822973

  6. The Essential Complexity of Auditory Receptive Fields

    PubMed Central

    Thorson, Ivar L.; Liénard, Jean; David, Stephen V.

    2015-01-01

    Encoding properties of sensory neurons are commonly modeled using linear finite impulse response (FIR) filters. For the auditory system, the FIR filter is instantiated in the spectro-temporal receptive field (STRF), often in the framework of the generalized linear model. Despite widespread use of the FIR STRF, numerous formulations for linear filters are possible that require many fewer parameters, potentially permitting more efficient and accurate model estimates. To explore these alternative STRF architectures, we recorded single-unit neural activity from auditory cortex of awake ferrets during presentation of natural sound stimuli. We compared performance of > 1000 linear STRF architectures, evaluating their ability to predict neural responses to a novel natural stimulus. Many were able to outperform the FIR filter. Two basic constraints on the architecture lead to the improved performance: (1) factorization of the STRF matrix into a small number of spectral and temporal filters and (2) low-dimensional parameterization of the factorized filters. The best parameterized model was able to outperform the full FIR filter in both primary and secondary auditory cortex, despite requiring fewer than 30 parameters, about 10% of the number required by the FIR filter. After accounting for noise from finite data sampling, these STRFs were able to explain an average of 40% of A1 response variance. The simpler models permitted more straightforward interpretation of sensory tuning properties. They also showed greater benefit from incorporating nonlinear terms, such as short term plasticity, that provide theoretical advances over the linear model. Architectures that minimize parameter count while maintaining maximum predictive power provide insight into the essential degrees of freedom governing auditory cortical function. They also maximize statistical power available for characterizing additional nonlinear properties that limit current auditory models. PMID:26683490

  7. The Essential Complexity of Auditory Receptive Fields.

    PubMed

    Thorson, Ivar L; Liénard, Jean; David, Stephen V

    2015-12-01

    Encoding properties of sensory neurons are commonly modeled using linear finite impulse response (FIR) filters. For the auditory system, the FIR filter is instantiated in the spectro-temporal receptive field (STRF), often in the framework of the generalized linear model. Despite widespread use of the FIR STRF, numerous formulations for linear filters are possible that require many fewer parameters, potentially permitting more efficient and accurate model estimates. To explore these alternative STRF architectures, we recorded single-unit neural activity from auditory cortex of awake ferrets during presentation of natural sound stimuli. We compared performance of > 1000 linear STRF architectures, evaluating their ability to predict neural responses to a novel natural stimulus. Many were able to outperform the FIR filter. Two basic constraints on the architecture lead to the improved performance: (1) factorization of the STRF matrix into a small number of spectral and temporal filters and (2) low-dimensional parameterization of the factorized filters. The best parameterized model was able to outperform the full FIR filter in both primary and secondary auditory cortex, despite requiring fewer than 30 parameters, about 10% of the number required by the FIR filter. After accounting for noise from finite data sampling, these STRFs were able to explain an average of 40% of A1 response variance. The simpler models permitted more straightforward interpretation of sensory tuning properties. They also showed greater benefit from incorporating nonlinear terms, such as short term plasticity, that provide theoretical advances over the linear model. Architectures that minimize parameter count while maintaining maximum predictive power provide insight into the essential degrees of freedom governing auditory cortical function. They also maximize statistical power available for characterizing additional nonlinear properties that limit current auditory models. PMID:26683490

  8. Mechanisms Underlying Development of Visual Maps and Receptive Fields

    PubMed Central

    Huberman, Andrew D.; Feller, Marla B.; Chapman, Barbara

    2008-01-01

    Patterns of synaptic connections in the visual system are remarkably precise. These connections dictate the receptive field properties of individual visual neurons and ultimately determine the quality of visual perception. Spontaneous neural activity is necessary for the development of various receptive field properties and visual feature maps. In recent years, attention has shifted to understanding the mechanisms by which spontaneous activity in the developing retina, lateral geniculate nucleus, and visual cortex instruct the axonal and dendritic refinements that give rise to orderly connections in the visual system. Axon guidance cues and a growing list of other molecules, including immune system factors, have also recently been implicated in visual circuit wiring. A major goal now is to determine how these molecules cooperate with spontaneous and visually evoked activity to give rise to the circuits underlying precise receptive field tuning and orderly visual maps. PMID:18558864

  9. Active vision and receptive field development in evolutionary robots.

    PubMed

    Floreano, Dario; Suzuki, Mototaka; Mattiussi, Dario

    2005-01-01

    In this paper, we describe the artificial evolution of adaptive neural controllers for an outdoor mobile robot equipped with a mobile camera. The robot can dynamically select the gazing direction by moving the body and/or the camera. The neural control system, which maps visual information to motor commands, is evolved online by means of a genetic algorithm, but the synaptic connections (receptive fields) from visual photoreceptors to internal neurons can also be modified by Hebbian plasticity while the robot moves in the environment. We show that robots evolved in physics-based simulations with Hebbian visual plasticity display more robust adaptive behavior when transferred to real outdoor environments as compared to robots evolved without visual plasticity. We also show that the formation of visual receptive fields is significantly and consistently affected by active vision as compared to the formation of receptive fields with grid sample images in the environment of the robot. Finally, we show that the interplay between active vision and receptive field formation amounts to the selection and exploitation of a small and constant subset of visual features available to the robot.

  10. Synaptic rewiring for topographic mapping and receptive field development.

    PubMed

    Bamford, Simeon A; Murray, Alan F; Willshaw, David J

    2010-05-01

    A model of topographic map refinement is presented which combines both weight plasticity and the formation and elimination of synapses, as well as both activity-dependent and activity-independent processes. The question of whether an activity-dependent process can refine a mapping created by an activity-independent process is addressed statistically. A new method of evaluating the quality of topographic projections is presented which allows independent consideration of the development of the centres and spatial variances of receptive fields for a projection. Synapse formation and elimination embed in the network topology changes in the weight distributions of synapses due to the activity-dependent learning rule used (spike-timing-dependent plasticity). In this model, the spatial variance of receptive fields can be reduced by an activity-dependent mechanism with or without spatially correlated inputs, but the accuracy of receptive field centres will not necessarily improve when synapses are formed based on distributions with on-average perfect topography. PMID:20176460

  11. Ontogenesis of receptive fields in the rabbit striate cortex

    NASA Technical Reports Server (NTRS)

    Mathers, L. H.; Chow, K. L.; Spear, P. D.; Grobstein, P.

    1974-01-01

    The development of receptive fields in rabbit pups was investigated by measuring their responses to various light stimuli and to electric shock delivered to the optic nerve head. The pups ranged in age from three to twenty-five days, allowing correlation of findings with maturation. The data, classified according to relation with symmetric or asymmetric field types, strongly suggest that retina maturation is the key factor in the rate of development in central visual pathways, and that central synaptic connections are made before the onset of retinal activity.

  12. Mapping of Visual Receptive Fields by Tomographic Reconstruction

    PubMed Central

    Pipa, Gordon; Chen, Zhe; Neuenschwander, Sergio; Lima, Bruss; Brown, Emery N.

    2014-01-01

    The moving bar experiment is a classic paradigm for characterizing the receptive field (RF) properties of neurons in primary visual cortex (V1). Current approaches for analyzing neural spiking activity recorded from these experiments do not take into account the point process nature of these data and the circular geometry of the stimulus presentation. We present a novel analysis approach to mapping V1 receptive fields that combines point process generalized linear models (PPGLM) with tomographic reconstruction computed by filtered-back projection. We use the method to map the RF sizes and orientations of 251 V1 neurons recorded from two macaque monkeys during a moving bar experiment. Our cross-validated goodness-of-fit analyses show that the PPGLM provides a more accurate characterization of spike train data than analyses based on rate functions computed by the methods of spike triggered averages or first-order Wiener-Volterra kernel. Our analysis leads to a new definition of RF size as the spatial area over which the spiking activity is significantly greater than baseline activity. Our approach yields larger RF sizes and sharper orientation tuning estimates. The tomographic reconstruction paradigm further suggests an efficient approach to choosing the number of directions and the number of trials per direction in designing moving bar experiments. Our results demonstrate that standard tomographic principles for image reconstruction can be adapted to characterize V1 RFs and that two fundamental properties, size and orientation, may be substantially different from what is currently reported. PMID:22734491

  13. Receptive fields and functional architecture of monkey striate cortex.

    PubMed

    Hubel, D H; Wiesel, T N

    1968-03-01

    1. The striate cortex was studied in lightly anaesthetized macaque and spider monkeys by recording extracellularly from single units and stimulating the retinas with spots or patterns of light. Most cells can be categorized as simple, complex, or hypercomplex, with response properties very similar to those previously described in the cat. On the average, however, receptive fields are smaller, and there is a greater sensitivity to changes in stimulus orientation. A small proportion of the cells are colour coded.2. Evidence is presented for at least two independent systems of columns extending vertically from surface to white matter. Columns of the first type contain cells with common receptive-field orientations. They are similar to the orientation columns described in the cat, but are probably smaller in cross-sectional area. In the second system cells are aggregated into columns according to eye preference. The ocular dominance columns are larger than the orientation columns, and the two sets of boundaries seem to be independent.3. There is a tendency for cells to be grouped according to symmetry of responses to movement; in some regions the cells respond equally well to the two opposite directions of movement of a line, but other regions contain a mixture of cells favouring one direction and cells favouring the other.4. A horizontal organization corresponding to the cortical layering can also be discerned. The upper layers (II and the upper two-thirds of III) contain complex and hypercomplex cells, but simple cells are virtually absent. The cells are mostly binocularly driven. Simple cells are found deep in layer III, and in IV A and IV B. In layer IV B they form a large proportion of the population, whereas complex cells are rare. In layers IV A and IV B one finds units lacking orientation specificity; it is not clear whether these are cell bodies or axons of geniculate cells. In layer IV most cells are driven by one eye only; this layer consists of a mosaic

  14. Efficient Receptive Field Tiling in Primate V1.

    PubMed

    Nauhaus, Ian; Nielsen, Kristina J; Callaway, Edward M

    2016-08-17

    The primary visual cortex (V1) encodes a diverse set of visual features, including orientation, ocular dominance (OD), and spatial frequency (SF), whose joint organization must be precisely structured to optimize coverage within the retinotopic map. Prior experiments have only identified efficient coverage based on orthogonal maps. Here we used two-photon calcium imaging to reveal an alternative arrangement for OD and SF maps in macaque V1; their gradients run parallel but with unique spatial periods, whereby low-SF regions coincide with monocular regions. Next we mapped receptive fields and found surprisingly precise micro-retinotopy that yields a smaller point-image and requires more efficient inter-map geometry, thus underscoring the significance of map relationships. While smooth retinotopy is constraining, studies suggest that it improves both wiring economy and the V1 population code read downstream. Altogether, these data indicate that connectivity within V1 is finely tuned and precise at the level of individual neurons. PMID:27499086

  15. Spatial invariance of visual receptive fields in parietal cortex neurons.

    PubMed

    Duhamel, J R; Bremmer, F; Ben Hamed, S; Graf, W

    1997-10-23

    Spatial information is conveyed to the primary visual cortex in retinal coordinates. Movement trajectory programming, however, requires a transformation from this sensory frame of reference into a frame appropriate for the selected part of the body, such as the eye, head or arms. To achieve this transformation, visual information must be combined with information from other sources: for instance, the location of an object of interest can be defined with respect to the observer's head if the position of the eyes in the orbit is known and is added to the object's retinal coordinates. Here we show that in a subdivision of the monkey parietal lobe, the ventral intraparietal area (VIP), the activity of visual neurons is modulated by eye-position signals, as in many other areas of the cortical visual system. We find that individual receptive fields of a population of VIP neurons are organized along a continuum, from eye to head coordinates. In the latter case, neurons encode the azimuth and/or elevation of a visual stimulus, independently of the direction in which the eyes are looking, thus representing spatial locations explicitly in at least a head-centred frame of reference. PMID:9349815

  16. Effects of spike-triggered negative feedback on receptive-field properties.

    PubMed

    Urdapilleta, Eugenio; Samengo, Inés

    2015-04-01

    Sensory neurons are often described in terms of a receptive field, that is, a linear kernel through which stimuli are filtered before they are further processed. If information transmission is assumed to proceed in a feedforward cascade, the receptive field may be interpreted as the external stimulus' profile maximizing neuronal output. The nervous system, however, contains many feedback loops, and sensory neurons filter more currents than the ones representing the transduced external stimulus. Some of the additional currents are generated by the output activity of the neuron itself, and therefore constitute feedback signals. By means of a time-frequency analysis of the input/output transformation, here we show how feedback modifies the receptive field. The model is applicable to various types of feedback processes, from spike-triggered intrinsic conductances to inhibitory synaptic inputs from nearby neurons. We distinguish between the intrinsic receptive field (filtering all input currents) and the effective receptive field (filtering only external stimuli). Whereas the intrinsic receptive field summarizes the biophysical properties of the neuron associated to subthreshold integration and spike generation, only the effective receptive field can be interpreted as the external stimulus' profile maximizing neuronal output. We demonstrate that spike-triggered feedback shifts low-pass filtering towards band-pass processing, transforming integrator neurons into resonators. For strong feedback, a sharp resonance in the spectral neuronal selectivity may appear. Our results provide a unified framework to interpret a collection of previous experimental studies where specific feedback mechanisms were shown to modify the filtering properties of neurons.

  17. Modeling attention-driven plasticity in auditory cortical receptive fields

    PubMed Central

    Carlin, Michael A.; Elhilali, Mounya

    2015-01-01

    To navigate complex acoustic environments, listeners adapt neural processes to focus on behaviorally relevant sounds in the acoustic foreground while minimizing the impact of distractors in the background, an ability referred to as top-down selective attention. Particularly striking examples of attention-driven plasticity have been reported in primary auditory cortex via dynamic reshaping of spectro-temporal receptive fields (STRFs). By enhancing the neural response to features of the foreground while suppressing those to the background, STRFs can act as adaptive contrast matched filters that directly contribute to an improved cognitive segregation between behaviorally relevant and irrelevant sounds. In this study, we propose a novel discriminative framework for modeling attention-driven plasticity of STRFs in primary auditory cortex. The model describes a general strategy for cortical plasticity via an optimization that maximizes discriminability between the foreground and distractors while maintaining a degree of stability in the cortical representation. The first instantiation of the model describes a form of feature-based attention and yields STRF adaptation patterns consistent with a contrast matched filter previously reported in neurophysiological studies. An extension of the model captures a form of object-based attention, where top-down signals act on an abstracted representation of the sensory input characterized in the modulation domain. The object-based model makes explicit predictions in line with limited neurophysiological data currently available but can be readily evaluated experimentally. Finally, we draw parallels between the model and anatomical circuits reported to be engaged during active attention. The proposed model strongly suggests an interpretation of attention-driven plasticity as a discriminative adaptation operating at the level of sensory cortex, in line with similar strategies previously described across different sensory modalities

  18. Beyond the classical receptive field: The effect of contextual stimuli.

    PubMed

    Spillmann, Lothar; Dresp-Langley, Birgitta; Tseng, Chia-Huei

    2015-01-01

    Following the pioneering studies of the receptive field (RF), the RF concept gained further significance for visual perception by the discovery of input effects from beyond the classical RF. These studies demonstrated that neuronal responses could be modulated by stimuli outside their RFs, consistent with the perception of induced brightness, color, orientation, and motion. Lesion scotomata are similarly modulated perceptually from the surround by RFs that have migrated from the interior to the outer edge of the scotoma and in this way provide filling-in of the void. Large RFs are advantageous to this task. In higher visual areas, such as the middle temporal and inferotemporal lobe, RFs increase in size and lose most of their retinotopic organization while encoding increasingly complex features. Whereas lower-level RFs mediate perceptual filling-in, contour integration, and figure-ground segregation, RFs at higher levels serve the perception of grouping by common fate, biological motion, and other biologically relevant stimuli, such as faces. Studies in alert monkeys while freely viewing natural scenes showed that classical and nonclassical RFs cooperate in forming representations of the visual world. Today, our understanding of the mechanisms underlying the RF is undergoing a quantum leap. What had started out as a hierarchical feed-forward concept for simple stimuli, such as spots, lines, and bars, now refers to mechanisms involving ascending, descending, and lateral signal flow. By extension of the bottom-up paradigm, RFs are nowadays understood as adaptive processors, enabling the predictive coding of complex scenes. Top-down effects guiding attention and tuned to task-relevant information complement the bottom-up analysis. PMID:26200888

  19. Receptive fields of visual neurons: the early years.

    PubMed

    Spillmann, Lothar

    2014-01-01

    This paper traces the history of the visual receptive field (RF) from Hartline to Hubel and Wiesel. Hartline (1938, 1940) found that an isolated optic nerve fiber in the frog could be excited by light falling on a small circular area of the retina. He called this area the RF, using a term first introduced by Sherrington (1906) in the tactile domain. In 1953 Kuffler discovered the antagonistic center-surround organization of cat RFs, and Barlow, Fitzhugh, and Kuffler (1957) extended this work to stimulus size and state of adaptation. Shortly thereafter, Lettvin and colleagues (1959) in an iconic paper asked "what the frog's eye tells the frog's brain". Meanwhile, Jung and colleagues (1952-1973) searched for the perceptual correlates of neuronal responses, and Jung and Spillmann (1970) proposed the term perceptive field (PF) as a psychophysical correlate of the RF. The Westheimer function (1967) enabled psychophysical measurements of the PF center and surround in human and monkey, which correlated closely with the underlying RF organization. The sixties and seventies were marked by rapid progress in RF research. Hubel and Wiesel (1959-1974), recording from neurons in the visual cortex of the cat and monkey, found elongated RFs selective for the shape, orientation, and position of the stimulus, as well as for movement direction and ocularity. These findings prompted the emergence in visual psychophysics of the concept of feature detectors selective for lines, bars, and edges, and contributed to a model of the RF in terms of difference of Gaussians (DOG) and Fourier channels. The distinction between simple, complex, and hypercomplex neurons followed. Although RF size increases towards the peripheral retina, its cortical representation remains constant due to the reciprocal relationship with the cortical magnification factor (M). This constitutes a uniform yardstick for M-scaled stimuli across the retina. Developmental studies have shown that RF properties are not fixed

  20. State-space receptive fields of semicircular canal afferent neurons in the bullfrog

    NASA Technical Reports Server (NTRS)

    Paulin, M. G.; Hoffman, L. F.

    2001-01-01

    Receptive fields are commonly used to describe spatial characteristics of sensory neuron responses. They can be extended to characterize temporal or dynamical aspects by mapping neural responses in dynamical state spaces. The state-space receptive field of a neuron is the probability distribution of the dynamical state of the stimulus-generating system conditioned upon the occurrence of a spike. We have computed state-space receptive fields for semicircular canal afferent neurons in the bullfrog (Rana catesbeiana). We recorded spike times during broad-band Gaussian noise rotational velocity stimuli, computed the frequency distribution of head states at spike times, and normalized these to obtain conditional pdfs for the state. These state-space receptive fields quantify what the brain can deduce about the dynamical state of the head when a single spike arrives from the periphery. c2001 Elsevier Science B.V. All rights reserved.

  1. Increasing Spontaneous Retinal Activity before Eye Opening Accelerates the Development of Geniculate Receptive Fields.

    PubMed

    Davis, Zachary W; Chapman, Barbara; Cheng, Hwai-Jong

    2015-10-28

    Visually evoked activity is necessary for the normal development of the visual system. However, little is known about the capacity for patterned spontaneous activity to drive the maturation of receptive fields before visual experience. Retinal waves provide instructive retinotopic information for the anatomical organization of the visual thalamus. To determine whether retinal waves also drive the maturation of functional responses, we increased the frequency of retinal waves pharmacologically in the ferret (Mustela putorius furo) during a period of retinogeniculate development before eye opening. The development of geniculate receptive fields after receiving these increased neural activities was measured using single-unit electrophysiology. We found that increased retinal waves accelerate the developmental reduction of geniculate receptive field sizes. This reduction is due to a decrease in receptive field center size rather than an increase in inhibitory surround strength. This work reveals an instructive role for patterned spontaneous activity in guiding the functional development of neural circuits. PMID:26511250

  2. Receptive fields of retinal bipolar cells are mediated by heterogeneous synaptic circuitry

    PubMed Central

    Zhang, Ai-Jun; Wu, Samuel M.

    2009-01-01

    Center-surround antagonistic receptive field (CSARF) organization is the basic synaptic circuit that serves as elementary building blocks for spatial information processing in the visual system. Cells with such receptive fields converge into higher-order visual neurons to form more complex receptive fields. Retinal bipolar cells (BCs) are the first neurons along the visual pathway that exhibit CSARF organization. BCs have been classified according to their response polarities and rod/cone inputs, and they project signals to target cells at different sublaminae of the inner plexiform layer. On the other hand, CSARFs of various types of BCs have been assumed be organized the same way. Here we examined center and surround responses of over 250 salamander BCs, and demonstrated that different types of BCs exhibit different patterns of dye coupling, receptive field center size, surround response strength, and conductance changes associated with center and surround responses. We show that BC receptive field center sizes varied with the degree of BC-BC coupling, and that surround responses of different BCs are mediated by different combinations of five lateral synaptic pathways mediated by the horizontal cells and amacrine cells. The finding of heterogeneous receptive field circuitry fundamentally challenges the common assumption that CSARFs of different subtypes of visual neurons are mediated by the same synaptic pathways. BCs carrying different visual signals use different synaptic circuits to process spatial information, allowing shape and contrast computation be differentially modulated by various lighting and adaptation conditions. PMID:19158304

  3. Crossed receptive field components and crossed dendrites in cat sacrocaudal dorsal horn.

    PubMed

    Gladfelter, W E; Millecchia, R J; Pubols, L M; Sonty, R V; Ritz, L A; Covalt-Dunning, D; Culberson, J; Brown, P B

    1993-10-01

    The hypothesis that sacrocaudal dorsal horn neurons with crossed receptive field components on the tail have dendrites which cross to the contralateral dorsal horn was tested in a combined electrophysiological and morphological study. Dorsal horn cells in the sacrocaudal spinal cord of anesthetized cats were penetrated with horseradish peroxidase-filled microelectrodes. After mapping their low threshold mechanoreceptive fields, cells were iontophoretically injected with horseradish peroxidase. A sample of 16 well-stained cells was obtained in laminae III and IV. Cells with receptive fields crossing the dorsal midline of the tail (n = 8) had somata in the lateral ipsilateral dorsal horn, and some of these cells (5/8) had dendrites which crossed to the lateral contralateral dorsal horn. Cells with receptive fields spanning the ventral midline (n = 2) were located near the center of the fused dorsal horn, and one of these had bilateral dendrites in this region. Cells with receptive fields on the lateral tail, crossing neither the dorsal nor the ventral midline (n = 6), had cell bodies in the middle of the ipsilateral dorsal horn; half had only ipsilateral dendrites, and half had crossed dendritic branches. Although the relationship between cell receptive field (RF) location (RF center, expressed as distance from tips of toes) and mediolateral location of the cell body was statistically significant, the correlation between crossed RF components and crossed dendritic branches was not significant. PMID:8254116

  4. Nonlinear Hebbian Learning as a Unifying Principle in Receptive Field Formation

    PubMed Central

    Gerstner, Wulfram

    2016-01-01

    The development of sensory receptive fields has been modeled in the past by a variety of models including normative models such as sparse coding or independent component analysis and bottom-up models such as spike-timing dependent plasticity or the Bienenstock-Cooper-Munro model of synaptic plasticity. Here we show that the above variety of approaches can all be unified into a single common principle, namely nonlinear Hebbian learning. When nonlinear Hebbian learning is applied to natural images, receptive field shapes were strongly constrained by the input statistics and preprocessing, but exhibited only modest variation across different choices of nonlinearities in neuron models or synaptic plasticity rules. Neither overcompleteness nor sparse network activity are necessary for the development of localized receptive fields. The analysis of alternative sensory modalities such as auditory models or V2 development lead to the same conclusions. In all examples, receptive fields can be predicted a priori by reformulating an abstract model as nonlinear Hebbian learning. Thus nonlinear Hebbian learning and natural statistics can account for many aspects of receptive field formation across models and sensory modalities. PMID:27690349

  5. Attention operates uniformly throughout the classical receptive field and the surround

    PubMed Central

    Verhoef, Bram-Ernst; Maunsell, John HR

    2016-01-01

    Shifting attention among visual stimuli at different locations modulates neuronal responses in heterogeneous ways, depending on where those stimuli lie within the receptive fields of neurons. Yet how attention interacts with the receptive-field structure of cortical neurons remains unclear. We measured neuronal responses in area V4 while monkeys shifted their attention among stimuli placed in different locations within and around neuronal receptive fields. We found that attention interacts uniformly with the spatially-varying excitation and suppression associated with the receptive field. This interaction explained the large variability in attention modulation across neurons, and a non-additive relationship among stimulus selectivity, stimulus-induced suppression and attention modulation that has not been previously described. A spatially-tuned normalization model precisely accounted for all observed attention modulations and for the spatial summation properties of neurons. These results provide a unified account of spatial summation and attention-related modulation across both the classical receptive field and the surround. DOI: http://dx.doi.org/10.7554/eLife.17256.001 PMID:27547989

  6. A new nonconvex variational approach for sensory neurons receptive field estimation

    NASA Astrophysics Data System (ADS)

    Drogoul, A.; Aubert, G.; Cessac, B.; Kornprobst, P.

    2016-10-01

    Determining the receptive field of a visual sensory neuron is crucial to characterize the region of the visual field and the stimuli this neuron is sensitive to. We propose a new method to estimate receptive fields by a nonconvex variational approach, thus relaxing the simplifying and unrealistic assumption of convexity made by standard approaches. The method consists of solving a relaxed discrete energy minimization problem using a proximal alternating algorithm. We compare our approach with the classical spike-triggered-average technique on simulated data, considering a typical retinal ganglion cell as ground truth. Results show a high improvement in terms of accuracy and convergence with respect to the duration of the experiment.

  7. Nonlinear spatial integration in the receptive field surround of retinal ganglion cells.

    PubMed

    Takeshita, Daisuke; Gollisch, Tim

    2014-05-28

    Throughout different sensory systems, individual neurons integrate incoming signals over their receptive fields. The characteristics of this signal integration are crucial determinants for the neurons' functions. For ganglion cells in the vertebrate retina, receptive fields are characterized by the well-known center-surround structure and, although several studies have addressed spatial integration in the receptive field center, little is known about how visual signals are integrated in the surround. Therefore, we set out here to characterize signal integration and to identify relevant nonlinearities in the receptive field surround of ganglion cells in the isolated salamander retina by recording spiking activity with extracellular electrodes under visual stimulation of the center and surround. To quantify nonlinearities of spatial integration independently of subsequent nonlinearities of spike generation, we applied the technique of iso-response measurements as follows: using closed-loop experiments, we searched for different stimulus patterns in the surround that all reduced the center-evoked spiking activity by the same amount. The identified iso-response stimuli revealed strongly nonlinear spatial integration in the receptive field surrounds of all recorded cells. Furthermore, cell types that had been shown previously to have different nonlinearities in receptive field centers showed similar surround nonlinearities but differed systematically in the adaptive characteristics of the surround. Finally, we found that there is an optimal spatial scale of surround suppression; suppression was most effective when surround stimulation was organized into subregions of several hundred micrometers in diameter, indicating that the surround is composed of subunits that have strong center-surround organization themselves. PMID:24872559

  8. Receptive field properties of neurons in the primary visual cortex under photopic and scotopic lighting conditions

    PubMed Central

    Duffy, Kevin R.; Hubel, David H.

    2009-01-01

    Knowledge of the physiology of the primate visual cortex (area V-1) comes mostly from studies done in photopic conditions, in which retinal cones are active and rods play little or no part. Conflicting results have come from research into the effects of dark adaptation on receptive field organization of cells in the retina and the lateral geniculate nucleus. These studies claim either that the effect of the surround disappears with dark adaptation or that it does not. The current study has as its objective a comparison of responses of V-1 cells in awake-alert macaque monkeys under conditions of light and dark adaptation. We reasoned that basic receptive field properties of V-1 cells such as orientation selectivity, direction selectivity, and end-stopping should be preserved in scotopic conditions if the receptive field organization of antecedent cells is maintained in dim light. Our results indicate that dark adaptation does not alter basic V-1 receptive field characteristics such as selectivity for orientation, direction, and bar length. PMID:17688906

  9. Diversity of receptive field changes in auditory cortex during natural sleep.

    PubMed

    Edeline, J M; Dutrieux, G; Manunta, Y; Hennevin, E

    2001-12-01

    Twenty years ago, the study by Livingstone and Hubel [(1981) Nature, 291, 554] was viewed as a first step toward understanding how changes in state of vigilance affect sensory processing. Since then, however, very few attempts have been made to progress in this direction. In the present study, 56 cells were recorded in the auditory cortex of adult, undrugged guinea pigs, and the frequency tuning curves were tested during continuous and stable periods of wakefulness and of slow-wave sleep (SWS). Twelve cells were also tested during paradoxical sleep. Over the whole cell population, the response latency, the frequency selectivity and the size of the suprathreshold receptive field were not significantly modified during SWS compared with waking. However, this lack of global effects resulted from the heterogeneity of response changes displayed by cortical cells. During SWS, the receptive field size varied as a function of the changes in evoked responses: it was unchanged for the cells whose evoked responses were not modified (38% of the cells), reduced for the cells whose responses were decreased (48%) and enlarged for the cells whose responses were increased (14%). This profile of changes differs from the prevalent receptive field shrinkage that was observed in the auditory thalamus during SWS [Edeline et al. (2000), J. Neurophysiol., 84, 934]. It also contrasts with the receptive field enlargement that was described under anaesthesia when the EEG spontaneously shifted from a desynchronized to a synchronized pattern [Wörgötter et al. (1998), Nature, 396, 165]. Reasons for these differences are discussed.

  10. Increasing Spontaneous Retinal Activity before Eye Opening Accelerates the Development of Geniculate Receptive Fields

    PubMed Central

    Davis, Zachary W.; Chapman, Barbara

    2015-01-01

    Visually evoked activity is necessary for the normal development of the visual system. However, little is known about the capacity for patterned spontaneous activity to drive the maturation of receptive fields before visual experience. Retinal waves provide instructive retinotopic information for the anatomical organization of the visual thalamus. To determine whether retinal waves also drive the maturation of functional responses, we increased the frequency of retinal waves pharmacologically in the ferret (Mustela putorius furo) during a period of retinogeniculate development before eye opening. The development of geniculate receptive fields after receiving these increased neural activities was measured using single-unit electrophysiology. We found that increased retinal waves accelerate the developmental reduction of geniculate receptive field sizes. This reduction is due to a decrease in receptive field center size rather than an increase in inhibitory surround strength. This work reveals an instructive role for patterned spontaneous activity in guiding the functional development of neural circuits. SIGNIFICANCE STATEMENT Patterned spontaneous neural activity that occurs during development is known to be necessary for the proper formation of neural circuits. However, it is unknown whether the spontaneous activity alone is sufficient to drive the maturation of the functional properties of neurons. Our work demonstrates for the first time an acceleration in the maturation of neural function as a consequence of driving patterned spontaneous activity during development. This work has implications for our understanding of how neural circuits can be modified actively to improve function prematurely or to recover from injury with guided interventions of patterned neural activity. PMID:26511250

  11. Reception and learning of electric fields in bees

    PubMed Central

    Greggers, Uwe; Koch, Gesche; Schmidt, Viola; Dürr, Aron; Floriou-Servou, Amalia; Piepenbrock, David; Göpfert, Martin C.; Menzel, Randolf

    2013-01-01

    Honeybees, like other insects, accumulate electric charge in flight, and when their body parts are moved or rubbed together. We report that bees emit constant and modulated electric fields when flying, landing, walking and during the waggle dance. The electric fields emitted by dancing bees consist of low- and high-frequency components. Both components induce passive antennal movements in stationary bees according to Coulomb's law. Bees learn both the constant and the modulated electric field components in the context of appetitive proboscis extension response conditioning. Using this paradigm, we identify mechanoreceptors in both joints of the antennae as sensors. Other mechanoreceptors on the bee body are potentially involved but are less sensitive. Using laser vibrometry, we show that the electrically charged flagellum is moved by constant and modulated electric fields and more strongly so if sound and electric fields interact. Recordings from axons of the Johnston organ document its sensitivity to electric field stimuli. Our analyses identify electric fields emanating from the surface charge of bees as stimuli for mechanoreceptors, and as biologically relevant stimuli, which may play a role in social communication. PMID:23536603

  12. Reception and learning of electric fields in bees.

    PubMed

    Greggers, Uwe; Koch, Gesche; Schmidt, Viola; Dürr, Aron; Floriou-Servou, Amalia; Piepenbrock, David; Göpfert, Martin C; Menzel, Randolf

    2013-05-22

    Honeybees, like other insects, accumulate electric charge in flight, and when their body parts are moved or rubbed together. We report that bees emit constant and modulated electric fields when flying, landing, walking and during the waggle dance. The electric fields emitted by dancing bees consist of low- and high-frequency components. Both components induce passive antennal movements in stationary bees according to Coulomb's law. Bees learn both the constant and the modulated electric field components in the context of appetitive proboscis extension response conditioning. Using this paradigm, we identify mechanoreceptors in both joints of the antennae as sensors. Other mechanoreceptors on the bee body are potentially involved but are less sensitive. Using laser vibrometry, we show that the electrically charged flagellum is moved by constant and modulated electric fields and more strongly so if sound and electric fields interact. Recordings from axons of the Johnston organ document its sensitivity to electric field stimuli. Our analyses identify electric fields emanating from the surface charge of bees as stimuli for mechanoreceptors, and as biologically relevant stimuli, which may play a role in social communication.

  13. Receptive field properties of rod-driven horizontal cells in the skate retina.

    PubMed

    Qian, H; Ripps, H

    1992-09-01

    The large receptive fields of retinal horizontal cells result primarily from extensive intercellular coupling via gap (electrical) junctions; thus, the extent of the receptive field provides an index of the degree to which the cells are electrically coupled. For rod-driven horizontal cells in the dark-adapted skate retina, a space constant of 1.18 +/- 0.15 mm (SD) was obtained from measurements with a moving slit stimulus, and a comparable value (1.43 +/- 0.55 mm) was obtained with variation in spot diameter. These values, and the extensive spread of a fluorescent dye (Lucifer Yellow) from the site of injection to neighboring cells, indicate that the horizontal cells of the all-rod retina of skate are well coupled electrically. Neither the receptive field properties nor the gap-junctional features of skate horizontal cells were influenced by the adaptive state of the retina: (a) the receptive field organization was unaffected by light adaptation, (b) similar dye coupling was seen in both dark- and light-adapted retinae, and (c) no significant differences were found in the gap-junctional particle densities measured in dark- and light-adapted retinas, i.e., 3,184 +/- 286/microns 2 (n = 8) and 3,073 +/- 494/microns 2 (n = 11), respectively. Moreover, the receptive fields of skate horizontal cells were not altered by either dopamine, glycine, GABA, or the GABAA receptor antagonists bicuculline and picrotoxin. We conclude that the rod-driven horizontal cells of the skate retina are tightly coupled to one another, and that the coupling is not affected by photic and pharmacological conditions that are known to modulate intercellular coupling between cone-driven horizontal cells in other species. PMID:1359000

  14. Investigation of the asymmetric distributions of RF transmission and reception fields at high static field.

    PubMed

    Watanabe, Hidehiro

    2012-01-01

    When radiofrequency (RF) transmission field represents B(1)(+), the reception field represents B(1)(-)*. The distribution of those maps demonstrates asymmetric features at high field magnetic resonance (MR) imaging. Both maps are in mirror symmetry to one another. Almost symmetric distribution of the B(1) field was expected on the laboratory frame in a symmetric sample loaded inside the RF coil designed to achieve a homogeneous B(1) field. Then, a simple change was made in the coordinate transformation equation of RF fields between the rotating and laboratory frames in both linear and quadrature modes to investigate the source of this feature of asymmetry. The magnitude of rotating frame components, B(1)(+) and B(1)(-), consists of the magnitude and the phase difference of the laboratory frame components. The rotating frame components differ in the sign of the sinusoidal phase difference. B(1)(+) is equal to B(1)(-) at lower field because phase changes that depend on position can be ignored. At higher fields, the magnitude component has a symmetric profile, and distribution in the phase component is antisymmetric. Thus, the distributions of B(1)(+) and B(1)(-) maps demonstrate mirror symmetry. Maps of magnitude and phase components were examined in the laboratory frame. Their maps were computed from B(1)(+) and B(1)(-) maps of the human brain and of a spherical saline phantom measured at 4.7T. It was concluded from these analytical and experimental results that the asymmetric and mirror symmetric distributions in B(1)(+) and B(1)(-) are derived from the phase difference in the laboratory frame. PMID:22790299

  15. Synaptic and Network Mechanisms of Sparse and Reliable Visual Cortical Activity during Nonclassical Receptive Field Stimulation

    PubMed Central

    Haider, Bilal; Krause, Matthew R.; Duque, Alvaro; Yu, Yuguo; Touryan, Jonathan; Mazer, James A.; McCormick, David A.

    2011-01-01

    SUMMARY During natural vision, the entire visual field is stimulated by images rich in spatiotemporal structure. Although many visual system studies restrict stimuli to the classical receptive field (CRF), it is known that costimulation of the CRF and the surrounding nonclassical receptive field (nCRF) increases neuronal response sparseness. The cellular and network mechanisms underlying increased response sparseness remain largely unexplored. Here we show that combined CRF + nCRF stimulation increases the sparseness, reliability, and precision of spiking and membrane potential responses in classical regular spiking (RSC) pyramidal neurons of cat primary visual cortex. Conversely, fast-spiking interneurons exhibit increased activity and decreased selectivity during CRF + nCRF stimulation. The increased sparseness and reliability of RSC neuron spiking is associated with increased inhibitory barrages and narrower visually evoked synaptic potentials. Our experimental observations were replicated with a simple computational model, suggesting that network interactions among neuronal subtypes ultimately sharpen recurrent excitation, producing specific and reliable visual responses. PMID:20152117

  16. Receptive fields for smooth pursuit eye movements and motion perception.

    PubMed

    Debono, Kurt; Schütz, Alexander C; Spering, Miriam; Gegenfurtner, Karl R

    2010-12-01

    Humans use smooth pursuit eye movements to track moving objects of interest. In order to track an object accurately, motion signals from the target have to be integrated and segmented from motion signals in the visual context. Most studies on pursuit eye movements used small visual targets against a featureless background, disregarding the requirements of our natural visual environment. Here, we tested the ability of the pursuit and the perceptual system to integrate motion signals across larger areas of the visual field. Stimuli were random-dot kinematograms containing a horizontal motion signal, which was perturbed by a spatially localized, peripheral motion signal. Perturbations appeared in a gaze-contingent coordinate system and had a different direction than the main motion including a vertical component. We measured pursuit and perceptual direction discrimination decisions and found that both steady-state pursuit and perception were influenced most by perturbation angles close to that of the main motion signal and only in regions close to the center of gaze. The narrow direction bandwidth (26 angular degrees full width at half height) and small spatial extent (8 degrees of visual angle standard deviation) correspond closely to tuning parameters of neurons in the middle temporal area (MT). PMID:20932990

  17. Distributed, layered and reliable computing nets to represent neuronal receptive fields.

    PubMed

    Moreno-Diaz, Arminda; de Blasio, Gabriel; Moreno-Diaz, Roberto

    2014-04-01

    Receptive fields of retinal and other sensory neurons show a large variety of spatiotemporal linear and non linear types of responses to local stimuli. In visual neurons, these responses present either asymmetric sensitive zones or center-surround organization. In most cases, the nature of the responses suggests the existence of a kind of distributed computation prior to the integration by the final cell which is evidently supported by the anatomy. We describe a new kind of discrete and continuous filters to model the kind of computations taking place in the receptive fields of retinal cells. To show their performance in the analysis of different non-trivial neuron-like structures, we use a computer tool specifically programmed by the authors to that effect. This tool is also extended to study the effect of lesions on the whole performance of our model nets.

  18. Responses and Receptive Fields of Amacrine Cells and Ganglion Cells in the Salamander Retina

    PubMed Central

    Zhang, Ai-Jun; Wu, Samuel M.

    2013-01-01

    Retinal amacrine cells (ACs) and ganglion cells (GCs) have been shown to display large morphological diversity, and here we show that four types of ACs and three types of GCs exhibit physiologically-distinguishable properties. They are the sustained ON ACs; sustained OFF ACs; transient ON-OFF ACs; transient ON-OFF ACs with wide receptive fields; sustained ON-center/OFF-surround GCs; sustained OFF-center/ON-surround GCs and transient ON-OFF GCs. By comparing response waveforms, receptive fields and relative rod/cone inputs of ACs and GCs with the corresponding parameters of various types of the presynaptic bipolar cells (BCs), we analyze how different types of BCs mediate synaptic inputs to various ACs and GCs. Although more types of third-order retinal neurons may be identified by more refined classification criteria, our observations suggest that many morphologically-distinct ACs and GCs share very similar physiological responses. PMID:20085780

  19. A simple analogue teaching device for demonstrating visual-receptive-field properties.

    PubMed

    Moulden, B; Martin, D

    1988-01-01

    A cheap (under 100 pounds at current prices) and simple analogue device is described which permits one to demonstrate, according to an adjustable configuration of the photoreceptive elements, some of the main properties of (i) circularly-symmetrical, (ii) 'simple' elongated opponent-flank, and (iii) multiple-discharge-centre visual receptive fields. The design and construction of the device are described, together with some suggested demonstrations.

  20. A Probabilistic Approach to Receptive Field Mapping in the Frontal Eye Fields

    PubMed Central

    Mayo, J. Patrick; Morrison, Robert M.; Smith, Matthew A.

    2016-01-01

    Studies of the neuronal mechanisms of perisaccadic vision often lack the resolution needed to determine important changes in receptive field (RF) structure. Such limited analytical power can lead to inaccurate descriptions of visuomotor processing. To address this issue, we developed a precise, probabilistic technique that uses a generalized linear model (GLM) for mapping the visual RFs of frontal eye field (FEF) neurons during stable fixation (Mayo et al., 2015). We previously found that full-field RF maps could be obtained using 1–8 dot stimuli presented at frame rates of 10–150 ms. FEF responses were generally robust to changes in the number of stimuli presented or the rate of presentation, which allowed us to visualize RFs over a range of spatial and temporal resolutions. Here, we compare the quality of RFs obtained over different stimulus and GLM parameters to facilitate future work on the detailed mapping of FEF RFs. We first evaluate the interactions between the number of stimuli presented per trial, the total number of trials, and the quality of RF mapping. Next, we vary the spatial resolution of our approach to illustrate the tradeoff between visualizing RF sub-structure and sampling at high resolutions. We then evaluate local smoothing as a possible correction for situations where under-sampling occurs. Finally, we provide a preliminary demonstration of the usefulness of a probabilistic approach for visualizing full-field perisaccadic RF shifts. Our results present a powerful, and perhaps necessary, framework for studying perisaccadic vision that is applicable to FEF and possibly other visuomotor regions of the brain. PMID:27047352

  1. Visual receptive field properties of neurons in the superficial superior colliculus of the mouse.

    PubMed

    Wang, Lupeng; Sarnaik, Rashmi; Rangarajan, Krsna; Liu, Xiaorong; Cang, Jianhua

    2010-12-01

    The mouse is a promising model in the study of visual system function and development because of available genetic tools. However, a quantitative analysis of visual receptive field properties had not been performed in the mouse superior colliculus (SC) despite its importance in mouse vision and its usefulness in developmental studies. We have made single-unit extracellular recordings from superficial layers of the SC in urethane-anesthetized C57BL/6 mice. We first map receptive fields with flashing spot stimuli and show that most SC neurons have spatially overlapped ON and OFF subfields. With drifting sinusoidal gratings, we then determine the tuning properties of individual SC neurons, including selectivity for stimulus direction and orientation, spatial frequency tuning, temporal frequency tuning, response linearity, and size preference. A wide range of receptive field sizes and selectivity are observed across the population and in various subtypes of SC neurons identified morphologically. In particular, orientation-selective responses are discovered in the mouse SC, and they are not affected by cortical lesion or long-term visual deprivation. However, ON/OFF characteristics and spatial frequency tuning of SC neurons are influenced by cortical inputs and require visual experience during development. Together, our results provide essential information for future investigations on the functional development of the superior colliculus. PMID:21147997

  2. Topographic receptive fields and patterned lateral interaction in a self-organizing model of the primary visual cortex.

    PubMed

    Sirosh, J; Miikkulainen, R

    1997-04-01

    This article presents a self-organizing neural network model for the simultaneous and cooperative development of topographic receptive fields and lateral interactions in cortical maps. Both afferent and lateral connections adapt by the same Hebbian mechanism in a purely local and unsupervised learning process. Afferent input weights of each neuron self-organize into hill-shaped profiles, receptive fields organize topographically across the network, and unique lateral interaction profiles develop for each neuron. The model demonstrates how patterned lateral connections developed based on correlated activity and explains why lateral connection patterns closely follow receptive field properties such as ocular dominance.

  3. Teaching Critical Reflexivity in Short-Term International Field Courses: Practices and Problems

    ERIC Educational Resources Information Center

    Glass, Michael R.

    2015-01-01

    This study critiques the use of critical reflexivity in short-term international field courses. Critical reflexivity's benefits include preparing students for professional research, deepening their learning, and giving the chance to see how student perspectives on fieldwork sites are influenced by their own identity and positionality. I use an…

  4. Division of labor in frontal eye field neurons during presaccadic remapping of visual receptive fields

    PubMed Central

    Shin, SooYoon

    2012-01-01

    Our percept of visual stability across saccadic eye movements may be mediated by presaccadic remapping. Just before a saccade, neurons that remap become visually responsive at a future field (FF), which anticipates the saccade vector. Hence, the neurons use corollary discharge of saccades. Many of the neurons also decrease their response at the receptive field (RF). Presaccadic remapping occurs in several brain areas including the frontal eye field (FEF), which receives corollary discharge of saccades in its layer IV from a collicular-thalamic pathway. We studied, at two levels, the microcircuitry of remapping in the FEF. At the laminar level, we compared remapping between layers IV and V. At the cellular level, we compared remapping between different neuron types of layer IV. In the FEF in four monkeys (Macaca mulatta), we identified 27 layer IV neurons with orthodromic stimulation and 57 layer V neurons with antidromic stimulation from the superior colliculus. With the use of established criteria, we classified the layer IV neurons as putative excitatory (n = 11), putative inhibitory (n = 12), or ambiguous (n = 4). We found that just before a saccade, putative excitatory neurons increased their visual response at the RF, putative inhibitory neurons showed no change, and ambiguous neurons increased their visual response at the FF. None of the neurons showed presaccadic visual changes at both RF and FF. In contrast, neurons in layer V showed full remapping (at both the RF and FF). Our data suggest that elemental signals for remapping are distributed across neuron types in early cortical processing and combined in later stages of cortical microcircuitry. PMID:22815407

  5. Laminar differences in receptive field properties of cells in cat primary visual cortex

    PubMed Central

    Gilbert, Charles D.

    1977-01-01

    1. Cells in area 17 of the cat visual cortex were studied with a view towards correlating receptive field properties with layering. A number of receptive field parameters were measured for all units, and nearly every unit was marked with a microlesion to determine accurately the layer in which it was found. 2. Cells were defined as simple or complex by mapping with stationary stimuli, using the criteria of Hubel & Wiesel (1962). Complex cells fell into two groups: those that showed summation for increased slit length (standard complex) and those that did not (special complex). 3. The simple cells were located in the deep part of layer 3, in layer 4, and in layer 6. This corresponds to the distribution of afferents from the dorsal layers of the lateral geniculate nucleus. In these cortical layers the simple cells differed primarily with respect to their receptive field size, cells in layer 4 having the smallest, layer 3 intermediate, and layer 6 the largest fields. Layer 4 was the only layer in which simple cells showed end-inhibition (a reduction in response to slits extending beyond the excitatory portion of the receptive field). 4. The standard complex cells were found in all layers, but were quite scarce in layer 4. As with the simple cells, field size varied with layer: in layer 2+3 they had small to intermediate field sizes, in layer 5 intermediate, and in layer 6 very large. Layer 6 cells showed summation for slits of increased length up to very large values, and responded best when the slits were centred in the receptive field. The only standard complex cells that showed end-inhibition were those in layer 2+3, and these were similar to the layer 4 simple cells in terms of proportion of end-inhibited units and degree of end-inhibition. 5. The special complex cells, originally described by Palmer & Rosenquist (1974), were found in two tiers: the upper one at the layer 3/layer 4 border and the lower one in layer 5. They were different from the standard complex

  6. 3-D components of a biological neural network visualized in computer generated imagery. I - Macular receptive field organization

    NASA Technical Reports Server (NTRS)

    Ross, Muriel D.; Cutler, Lynn; Meyer, Glenn; Lam, Tony; Vaziri, Parshaw

    1990-01-01

    Computer-assisted, 3-dimensional reconstructions of macular receptive fields and of their linkages into a neural network have revealed new information about macular functional organization. Both type I and type II hair cells are included in the receptive fields. The fields are rounded, oblong, or elongated, but gradations between categories are common. Cell polarizations are divergent. Morphologically, each calyx of oblong and elongated fields appears to be an information processing site. Intrinsic modulation of information processing is extensive and varies with the kind of field. Each reconstructed field differs in detail from every other, suggesting that an element of randomness is introduced developmentally and contributes to endorgan adaptability.

  7. Rapid Task-Related Plasticity of Spectrotemporal Receptive Fields in the Auditory Midbrain

    PubMed Central

    David, Stephen V.

    2015-01-01

    Previous research has demonstrated that auditory cortical neurons can modify their receptive fields when animals engage in auditory detection tasks. We tested for this form of task-related plasticity in the inferior colliculus (IC) of ferrets trained to detect a pure tone target in a sequence of noise distractors that did not overlap in time. During behavior, responses were suppressed at the target tone frequency in approximately half of IC neurons relative to the passive state. This suppression often resulted from a combination of a local tuning change and a global change in overall excitability. Local and global suppression were stronger when the target frequency was aligned to neuronal best frequency. Local suppression in the IC was indistinguishable from that described previously in auditory cortex, while global suppression was unique to the IC. The results demonstrate that engaging in an auditory task can change selectivity for task-relevant features in the midbrain, an area where these effects have not been reported previously. SIGNIFICANCE STATEMENT Previous studies have demonstrated that the receptive fields of cortical neurons are modified when animals engage in auditory behaviors, a process that is hypothesized to provide the basis for segregating sound sources in an auditory scene. This study demonstrates for the first time that receptive fields of neurons in the midbrain inferior colliculus are also modified during behavior. The magnitude of the tuning changes is similar to previous reports in cortex. These results support a hierarchical model of behaviorally driven sound segregation that begins in the subcortical auditory network. PMID:26400939

  8. Visual receptive fields in the striate-recipient zone of the lateral posterior-pulvinar complex.

    PubMed

    Chalupa, L M; Abramson, B P

    1989-01-01

    The lateral posterior (LP)-pulvinar complex of the cat is known to contain multiple visual areas. In the present study, we examined the receptive field properties of single neurons isolated in the lateral division of this complex (the LPI). The LPI is designated the striate-recipient zone because it is the only region of the LP-pulvinar receiving cortical projections from areas 17 and 18. The recordings revealed that the striate-recipient zone of LP comprises 2 subareas, which we have termed LPI-1 and LPI-2. In the main segment (LPI-1), virtually all cells responded securely to visual stimuli. The vast majority of these neurons were binocular, with relatively small and well-defined receptive fields. More than half of the cells were found to be directionally selective, and almost this many were orientation specific. The orientation tuning of these cells was found to be quite precise, comparable to complex cells in area 17. In contrast, in the small dorsolateral segment of the striate-recipient zone (the LPI-2), a substantial proportion of cells could not be visually activated. Here, the visual cells had very large receptive fields, and relatively few were direction or orientation selective. The LPI-2 receives subcortical inputs from the superficial layers of the superior colliculus, the hypothalamus, and cerebellum, while the LPI-1 is innervated only by cortical axons. It is suggested that the subcortical connections of the LPI-2 account for the differences in the response properties of the 2 striate-recipient areas. The present results, in conjunction with our previous findings on the principal tectorecipient zone (Chalupa et al., 1983), permit 2 generalizations regarding the functional organization of the cat's LP-pulvinar complex. First, there are clear differences among the visual areas of the LP-pulvinar in the cellular processing of visual information. Second, these functional differences can be related to the principal sources of visual input to the various

  9. Context dependence of spectro-temporal receptive fields with implications for neural coding.

    PubMed

    Eggermont, Jos J

    2011-01-01

    The spectro-temporal receptive field (STRF) is frequently used to characterize the linear frequency-time filter properties of the auditory system up to the neuron recorded from. STRFs are extremely stimulus dependent, reflecting the strong non-linearities in the auditory system. Changes in the STRF with stimulus type (tonal, noise-like, vocalizations), sound level and spectro-temporal sound density are reviewed here. Effects on STRF shape of task and attention are also briefly reviewed. Models to account for these changes, potential improvements to STRF analysis, and implications for neural coding are discussed. PMID:20123121

  10. [Receptive fields of cat striate neurons: dynamics of weight and topographical characteristics of the excitatory zone of the neuron receptive fields in the visual cortex].

    PubMed

    Lazareva, N A; Kozhukhov, S A; Sharaev, G A; Novikova, R V; Tikhomirov, A S; Tsutskiridze, D Iu; Shevelev, I A

    2010-01-01

    In 22 acute experiments on anesthetized and immobilized adult cats, the dynamics of 83 on- and/or off-receptive fields (RF) was studied in 47 striate neurons with the method of temporal slices by mapping with single-flash stimuli. The latency of the RF appearance was 88 +/- 5 ms, and its duration was 192 +/- 12 ms. Dynamical wavy changes in the RF sizes and weights repeating up to three times were revealed. The mean duration of one wave was 95 +/- 4 ms. In 99% of cases, the RF discharge center defined for one temporal slice also displaced in an undulatory way relatively the RF's center defined for whole analysis period. The mean duration of this undulatory cycle was 67.3 +/- 3 ms. In 72.5% of cases, the displacement of the discharge center followed different trajectories inscribed in an ellipse. The functional significance of such changes in the RFs of striate neurons is discussed with regard to the dynamics of their detector features and underlying mechanisms.

  11. Understanding spike-triggered covariance using Wiener theory for receptive field identification

    PubMed Central

    Sandler, Roman A.; Marmarelis, Vasilis Z.

    2015-01-01

    Receptive field identification is a vital problem in sensory neurophysiology and vision. Much research has been done in identifying the receptive fields of nonlinear neurons whose firing rate is determined by the nonlinear interactions of a small number of linear filters. Despite more advanced methods that have been proposed, spike-triggered covariance (STC) continues to be the most widely used method in such situations due to its simplicity and intuitiveness. Although the connection between STC and Wiener/Volterra kernels has often been mentioned in the literature, this relationship has never been explicitly derived. Here we derive this relationship and show that the STC matrix is actually a modified version of the second-order Wiener kernel, which incorporates the input autocorrelation and mixes first- and second-order dynamics. It is then shown how, with little modification of the STC method, the Wiener kernels may be obtained and, from them, the principal dynamic modes, a set of compact and efficient linear filters that essentially combine the spike-triggered average and STC matrix and generalize to systems with both continuous and point-process outputs. Finally, using Wiener theory, we show how these obtained filters may be corrected when they were estimated using correlated inputs. Our correction technique is shown to be superior to those commonly used in the literature for both correlated Gaussian images and natural images. PMID:26230978

  12. Spatial structure of cone inputs to receptive fields in primate lateral geniculate nucleus

    NASA Astrophysics Data System (ADS)

    Reid, R. Clay; Shapley, Robert M.

    1992-04-01

    HUMAN colour vision depends on three classes of cone photoreceptors, those sensitive to short (S), medium (M) or long (L) wavelengths, and on how signals from these cones are combined by neurons in the retina and brain. Macaque monkey colour vision is similar to human, and the receptive fields of macaque visual neurons have been used as an animal model of human colour processing1. P retinal ganglion cells and parvocellular neurons are colour-selective neurons in macaque retina and lateral geniculate nucleus. Interactions between cone signals feeding into these neurons are still unclear. On the basis of experimental results with chromatic adaptation, excitatory and inhibitory inputs from L and M cones onto P cells (and parvocellular neurons) were thought to be quite specific2,3 (Fig. la). But these experiments with spatially diffuse adaptation did not rule out the 'mixed-surround' hypothesis: that there might be one cone-specific mechanism, the receptive field centre, and a surround mechanism connected to all cone types indiscriminately (Fig. le). Recent work has tended to support the mixed-surround hypothesis4-8. We report here the development of new stimuli to measure spatial maps of the linear L-, M- and S-cone inputs to test the hypothesis definitively. Our measurements contradict the mixed-surround hypothesis and imply cone specificity in both centre and surround.

  13. Spectral-temporal receptive fields of nonlinear auditory neurons obtained using natural sounds.

    PubMed

    Theunissen, F E; Sen, K; Doupe, A J

    2000-03-15

    The stimulus-response function of many visual and auditory neurons has been described by a spatial-temporal receptive field (STRF), a linear model that for mathematical reasons has until recently been estimated with the reverse correlation method, using simple stimulus ensembles such as white noise. Such stimuli, however, often do not effectively activate high-level sensory neurons, which may be optimized to analyze natural sounds and images. We show that it is possible to overcome the simple-stimulus limitation and then use this approach to calculate the STRFs of avian auditory forebrain neurons from an ensemble of birdsongs. We find that in many cases the STRFs derived using natural sounds are strikingly different from the STRFs that we obtained using an ensemble of random tone pips. When we compare these two models by assessing their predictions of neural response to the actual data, we find that the STRFs obtained from natural sounds are superior. Our results show that the STRF model is an incomplete description of response properties of nonlinear auditory neurons, but that linear receptive fields are still useful models for understanding higher level sensory processing, as long as the STRFs are estimated from the responses to relevant complex stimuli.

  14. Neural response to natural stimuli: maximizing information to find the receptive fields

    NASA Astrophysics Data System (ADS)

    Sharpee, T.; Rust, N.; Bialek, William

    2002-03-01

    From olfaction to vision and audition, there is an increasing need, and a growing number of experiments, that study response of sensory neurons to natural stimuli. The fact that statistically simple stimuli, such as white noise, are often not effective in activating high-level neurons provides an indication that neural response cannot always be understood as a combination of responses to simple signals. However, rigorous statistical analysis of neural responses in terms of receptive fields is limited to correlated Gaussian inputs. Here we propose to look at the mutual information between an ensemble of stimuli and sequence of elicited neural responses as a function of direction in a stimulus space. By maximizing information first as a function of one angle, and then iteratively including new directions into a set of directions along which information is calculated and optimized, it is possible to find the relevant subspace that determines the probability of generating a response, provided that the number of relevant directions, or receptive fields, is small. Since the dimension of relevant subspace is much smaller than that of the overall stimulus space, it becomes experimentally feasible to map out the neuron's input/output function.

  15. Inner retinal inhibition shapes the receptive field of retinal ganglion cells in primate

    PubMed Central

    Protti, D A; Di Marco, S; Huang, J Y; Vonhoff, C R; Nguyen, V; Solomon, S G

    2014-01-01

    Abstract The centre–surround organisation of receptive fields is a feature of most retinal ganglion cells (RGCs) and is critical for spatial discrimination and contrast detection. Although lateral inhibitory processes are known to be important in generating the receptive field surround, the contribution of each of the two synaptic layers in the primate retina remains unclear. Here we studied the spatial organisation of excitatory and inhibitory synaptic inputs onto ON and OFF ganglion cells in the primate retina. All RGCs showed an increase in excitation in response to stimulus of preferred polarity. Inhibition onto RGCs comprised two types of responses to preferred polarity: some RGCs showed an increase in inhibition whilst others showed removal of tonic inhibition. Excitatory inputs were strongly spatially tuned but inhibitory inputs showed more variable organisation: in some neurons they were as strongly tuned as excitation, and in others inhibitory inputs showed no spatial tuning. We targeted one source of inner retinal inhibition by functionally ablating spiking amacrine cells with bath application of tetrodotoxin (TTX). TTX significantly reduced the spatial tuning of excitatory inputs. In addition, TTX reduced inhibition onto those RGCs where a stimulus of preferred polarity increased inhibition. Reconstruction of the spatial tuning properties by somatic injection of excitatory and inhibitory synaptic conductances verified that TTX-mediated inhibition onto bipolar cells increases the strength of the surround in RGC spiking output. These results indicate that in the primate retina inhibitory mechanisms in the inner plexiform layer sharpen the spatial tuning of ganglion cells. PMID:24042496

  16. Spatio-temporal receptive field properties of cells in the rat superior colliculus.

    PubMed

    Prévost, François; Lepore, Franco; Guillemot, Jean-Paul

    2007-04-20

    Although the rat is widely used in neurobehavioural research, the spatio-temporal receptive field properties of neurons in superficial layers of the superior colliculus are relatively unknown. Extracellular recordings were carried out in anesthetized Long Evans rats. Neurons in these layers had simple-like and complex-like receptive fields (RFs). Most cells (67%) had RFs showing band-pass and low-pass spatial frequency (SF) tuning profiles. Spatial band-pass profiles showed low optimal SF (mean=0.03 c/deg), low spatial resolution (mean=0.18 c/deg) and large spatial bandwidths (mean=2.3 octaves). More than two-thirds of the RFs (71%) were selective to orientation and only 11% were clearly direction selective. Nearly two-thirds of cells (68%) had band-pass temporal frequency (TF) tuning profiles with narrow bandwidths (mean=1.7 oct.) whereas the others showed low-pass TF tuning profiles. Temporal band-pass profiles had low optimal TFs (mean=3.5 c/s). Although some cells showed relatively low contrast thresholds (6%), most cells only responded to high contrast values (mean=38.2%). These results show that the spatial resolution of collicular cells is poor and that they respond mainly to highly contrasted moving stimuli.

  17. Spectral-temporal receptive fields of nonlinear auditory neurons obtained using natural sounds.

    PubMed

    Theunissen, F E; Sen, K; Doupe, A J

    2000-03-15

    The stimulus-response function of many visual and auditory neurons has been described by a spatial-temporal receptive field (STRF), a linear model that for mathematical reasons has until recently been estimated with the reverse correlation method, using simple stimulus ensembles such as white noise. Such stimuli, however, often do not effectively activate high-level sensory neurons, which may be optimized to analyze natural sounds and images. We show that it is possible to overcome the simple-stimulus limitation and then use this approach to calculate the STRFs of avian auditory forebrain neurons from an ensemble of birdsongs. We find that in many cases the STRFs derived using natural sounds are strikingly different from the STRFs that we obtained using an ensemble of random tone pips. When we compare these two models by assessing their predictions of neural response to the actual data, we find that the STRFs obtained from natural sounds are superior. Our results show that the STRF model is an incomplete description of response properties of nonlinear auditory neurons, but that linear receptive fields are still useful models for understanding higher level sensory processing, as long as the STRFs are estimated from the responses to relevant complex stimuli. PMID:10704507

  18. Subspace mapping of the three-dimensional spectral receptive field of macaque MT neurons.

    PubMed

    Inagaki, Mikio; Sasaki, Kota S; Hashimoto, Hajime; Ohzawa, Izumi

    2016-08-01

    Neurons in the middle temporal (MT) visual area are thought to represent the velocity (direction and speed) of motion. Previous studies suggest the importance of both excitation and suppression for creating velocity representation in MT; however, details of the organization of excitation and suppression at the MT stage are not understood fully. In this article, we examine how excitatory and suppressive inputs are pooled in individual MT neurons by measuring their receptive fields in a three-dimensional (3-D) spatiotemporal frequency domain. We recorded the activity of single MT neurons from anesthetized macaque monkeys. To achieve both quality and resolution of the receptive field estimations, we applied a subspace reverse correlation technique in which a stimulus sequence of superimposed multiple drifting gratings was cross-correlated with the spiking activity of neurons. Excitatory responses tended to be organized in a manner representing a specific velocity independent of the spatial pattern of the stimuli. Conversely, suppressive responses tended to be distributed broadly over the 3-D frequency domain, supporting a hypothesis of response normalization. Despite the nonspecific distributed profile, the total summed strength of suppression was comparable to that of excitation in many MT neurons. Furthermore, suppressive responses reduced the bandwidth of velocity tuning, indicating that suppression improves the reliability of velocity representation. Our results suggest that both well-organized excitatory inputs and broad suppressive inputs contribute significantly to the invariant and reliable representation of velocity in MT. PMID:27193321

  19. Experience-dependent specialization of receptive field surround for selective coding of natural scenes.

    PubMed

    Pecka, Michael; Han, Yunyun; Sader, Elie; Mrsic-Flogel, Thomas D

    2014-10-22

    At eye opening, neurons in primary visual cortex (V1) are selective for stimulus features, but circuits continue to refine in an experience-dependent manner for some weeks thereafter. How these changes contribute to the coding of visual features embedded in complex natural scenes remains unknown. Here we show that normal visual experience after eye opening is required for V1 neurons to develop a sensitivity for the statistical structure of natural stimuli extending beyond the boundaries of their receptive fields (RFs), which leads to improvements in coding efficiency for full-field natural scenes (increased selectivity and information rate). These improvements are mediated by an experience-dependent increase in the effectiveness of natural surround stimuli to hyperpolarize the membrane potential specifically during RF-stimulus epochs triggering action potentials. We suggest that neural circuits underlying surround modulation are shaped by the statistical structure of visual input, which leads to more selective coding of features in natural scenes. PMID:25263755

  20. A Feedback Model of Attention Explains the Diverse Effects of Attention on Neural Firing Rates and Receptive Field Structure.

    PubMed

    Miconi, Thomas; VanRullen, Rufin

    2016-02-01

    Visual attention has many effects on neural responses, producing complex changes in firing rates, as well as modifying the structure and size of receptive fields, both in topological and feature space. Several existing models of attention suggest that these effects arise from selective modulation of neural inputs. However, anatomical and physiological observations suggest that attentional modulation targets higher levels of the visual system (such as V4 or MT) rather than input areas (such as V1). Here we propose a simple mechanism that explains how a top-down attentional modulation, falling on higher visual areas, can produce the observed effects of attention on neural responses. Our model requires only the existence of modulatory feedback connections between areas, and short-range lateral inhibition within each area. Feedback connections redistribute the top-down modulation to lower areas, which in turn alters the inputs of other higher-area cells, including those that did not receive the initial modulation. This produces firing rate modulations and receptive field shifts. Simultaneously, short-range lateral inhibition between neighboring cells produce competitive effects that are automatically scaled to receptive field size in any given area. Our model reproduces the observed attentional effects on response rates (response gain, input gain, biased competition automatically scaled to receptive field size) and receptive field structure (shifts and resizing of receptive fields both spatially and in complex feature space), without modifying model parameters. Our model also makes the novel prediction that attentional effects on response curves should shift from response gain to contrast gain as the spatial focus of attention drifts away from the studied cell. PMID:26890584

  1. Spatiotemporal profiles of receptive fields of neurons in the lateral posterior nucleus of the cat LP-pulvinar complex

    PubMed Central

    Piché, Marilyse; Thomas, Sébastien

    2015-01-01

    The pulvinar is the largest extrageniculate thalamic visual nucleus in mammals. It establishes reciprocal connections with virtually all visual cortexes and likely plays a role in transthalamic cortico-cortical communication. In cats, the lateral posterior nucleus (LP) of the LP-pulvinar complex can be subdivided in two subregions, the lateral (LPl) and medial (LPm) parts, which receive a predominant input from the striate cortex and the superior colliculus, respectively. Here, we revisit the receptive field structure of LPl and LPm cells in anesthetized cats by determining their first-order spatiotemporal profiles through reverse correlation analysis following sparse noise stimulation. Our data reveal the existence of previously unidentified receptive field profiles in the LP nucleus both in space and time domains. While some cells responded to only one stimulus polarity, the majority of neurons had receptive fields comprised of bright and dark responsive subfields. For these neurons, dark subfields' size was larger than that of bright subfields. A variety of receptive field spatial organization types were identified, ranging from totally overlapped to segregated bright and dark subfields. In the time domain, a large spectrum of activity overlap was found, from cells with temporally coinciding subfield activity to neurons with distinct, time-dissociated subfield peak activity windows. We also found LP neurons with space-time inseparable receptive fields and neurons with multiple activity periods. Finally, a substantial degree of homology was found between LPl and LPm first-order receptive field spatiotemporal profiles, suggesting a high integration of cortical and subcortical inputs within the LP-pulvinar complex. PMID:26289469

  2. Infant reflexes

    MedlinePlus

    ... neck reflex; Galant reflex; Truncal incurvation; Rooting reflex; Parachute reflex; Grasp reflex ... was stroked and begin to make sucking motions. PARACHUTE REFLEX This reflex occurs in slightly older infants ...

  3. Comparison of visual receptive field properties of the superior colliculus and primary visual cortex in rats.

    PubMed

    Li, Xiaoyuan; Sun, Chaokui; Shi, Li

    2015-08-01

    The rat visual system comprises cortical and subcortical pathways. The receptive field properties of cells in the visual cortex have been extensively studied; however, the fundamental roles of the two circuits in visual information processing are not well understood. To address this question, we have applied quantitative methods to compare and characterize the spatiotemporal receptive field (RF) properties of neurons in primary visual cortex (V1) cells and superficial layers of the superior colliculus (SC) in rats by means of extracellular recordings. An analysis of visual stimulus processing revealed distinct functional characteristics of the two visual circuits. RF diameters of SC neurons were significantly larger than those of V1 cells. Most cells in both regions had high orientation selectivity, but the mean orientation bandwidth of the SC was broader than that of V1 cells (101.5° vs. 60.2°). The mean optimal spatial frequency (SF) of SC cells was lower but had a broader bandwidth than that of V1 cells (0.03 vs. 0.068 cpd). The majority of SC and V1 cells (70% and 68%, respectively) had RFs with band-pass temporal frequency (TF) tuning profiles and similar optimal TFs. However, temporal band-pass profiles of the SC showed narrower mean temporal bandwidths than those of V1 cells (1.42 vs. 2.36 octaves). The majority of neurons in visual cortical and subcortical structures were activated in response to high-contrast, drifting gratings in the preferred orientation. The percentage of V1 neurons with a low-contrast threshold was larger than the proportion of SC neurons (45.6% vs. 30%), indicating that the former adapt better to contrast. The substantial overlap in latency distributions between SC and V1 areas suggests that the two visual systems process and analyze visual signals in parallel. However, the two areas use different neural encoding mechanisms based on different latency distribution trends. These results indicate that SC cells have poor spatial acuity

  4. Delayed inhibition in cortical receptive fields and the discrimination of complex stimuli.

    PubMed

    Narayan, Rajiv; Ergün, Ayla; Sen, Kamal

    2005-10-01

    Although auditory cortex is thought to play an important role in processing complex natural sounds such as speech and animal vocalizations, the specific functional roles of cortical receptive fields (RFs) remain unclear. Here, we study the relationship between a behaviorally important function: the discrimination of natural sounds and the structure of cortical RFs. We examine this problem in the model system of songbirds, using a computational approach. First, we constructed model neurons based on the spectral temporal RF (STRF), a widely used description of auditory cortical RFs. We focused on delayed inhibitory STRFs, a class of STRFs experimentally observed in primary auditory cortex (ACx) and its analog in songbirds (field L), which consist of an excitatory subregion and a delayed inhibitory subregion cotuned to a characteristic frequency. We quantified the discrimination of birdsongs by model neurons, examining both the dynamics and temporal resolution of discrimination, using a recently proposed spike distance metric (SDM). We found that single model neurons with delayed inhibitory STRFs can discriminate accurately between songs. Discrimination improves dramatically when the temporal structure of the neural response at fine timescales is considered. When we compared discrimination by model neurons with and without the inhibitory subregion, we found that the presence of the inhibitory subregion can improve discrimination. Finally, we modeled a cortical microcircuit with delayed synaptic inhibition, a candidate mechanism underlying delayed inhibitory STRFs, and showed that blocking inhibition in this model circuit degrades discrimination.

  5. Emulating the Visual Receptive Field Properties of MST Neurons with a Template Model of Heading Estimation

    NASA Technical Reports Server (NTRS)

    Perrone, John A.; Stone, Leland S.

    1997-01-01

    We have previously proposed a computational neural-network model by which the complex patterns of retinal image motion generated during locomotion (optic flow) can be processed by specialized detectors acting as templates for specific instances of self-motion. The detectors in this template model respond to global optic flow by sampling image motion over a large portion of the visual field through networks of local motion sensors with properties similar to neurons found in the middle temporal (MT) area of primate extrastriate visual cortex. The model detectors were designed to extract self-translation (heading), self-rotation, as well as the scene layout (relative distances) ahead of a moving observer, and are arranged in cortical-like heading maps to perform this function. Heading estimation from optic flow has been postulated by some to be implemented within the medial superior temporal (MST) area. Others have questioned whether MST neurons can fulfill this role because some of their receptive-field properties appear inconsistent with a role in heading estimation. To resolve this issue, we systematically compared MST single-unit responses with the outputs of model detectors under matched stimulus conditions. We found that the basic physiological properties of MST neurons can be explained by the template model. We conclude that MST neurons are well suited to support heading estimation and that the template model provides an explicit set of testable hypotheses which can guide future exploration of MST and adjacent areas within the primate superior temporal sulcus.

  6. Delayed inhibition in cortical receptive fields and the discrimination of complex stimuli.

    PubMed

    Narayan, Rajiv; Ergün, Ayla; Sen, Kamal

    2005-10-01

    Although auditory cortex is thought to play an important role in processing complex natural sounds such as speech and animal vocalizations, the specific functional roles of cortical receptive fields (RFs) remain unclear. Here, we study the relationship between a behaviorally important function: the discrimination of natural sounds and the structure of cortical RFs. We examine this problem in the model system of songbirds, using a computational approach. First, we constructed model neurons based on the spectral temporal RF (STRF), a widely used description of auditory cortical RFs. We focused on delayed inhibitory STRFs, a class of STRFs experimentally observed in primary auditory cortex (ACx) and its analog in songbirds (field L), which consist of an excitatory subregion and a delayed inhibitory subregion cotuned to a characteristic frequency. We quantified the discrimination of birdsongs by model neurons, examining both the dynamics and temporal resolution of discrimination, using a recently proposed spike distance metric (SDM). We found that single model neurons with delayed inhibitory STRFs can discriminate accurately between songs. Discrimination improves dramatically when the temporal structure of the neural response at fine timescales is considered. When we compared discrimination by model neurons with and without the inhibitory subregion, we found that the presence of the inhibitory subregion can improve discrimination. Finally, we modeled a cortical microcircuit with delayed synaptic inhibition, a candidate mechanism underlying delayed inhibitory STRFs, and showed that blocking inhibition in this model circuit degrades discrimination. PMID:15917327

  7. Experience-Dependent Specialization of Receptive Field Surround for Selective Coding of Natural Scenes

    PubMed Central

    Pecka, Michael; Han, Yunyun; Sader, Elie; Mrsic-Flogel, Thomas D.

    2014-01-01

    Summary At eye opening, neurons in primary visual cortex (V1) are selective for stimulus features, but circuits continue to refine in an experience-dependent manner for some weeks thereafter. How these changes contribute to the coding of visual features embedded in complex natural scenes remains unknown. Here we show that normal visual experience after eye opening is required for V1 neurons to develop a sensitivity for the statistical structure of natural stimuli extending beyond the boundaries of their receptive fields (RFs), which leads to improvements in coding efficiency for full-field natural scenes (increased selectivity and information rate). These improvements are mediated by an experience-dependent increase in the effectiveness of natural surround stimuli to hyperpolarize the membrane potential specifically during RF-stimulus epochs triggering action potentials. We suggest that neural circuits underlying surround modulation are shaped by the statistical structure of visual input, which leads to more selective coding of features in natural scenes. PMID:25263755

  8. Generation of the receptive fields of subpial cells in turtle visual cortex.

    PubMed

    Wang, Wenxue; Luo, Sean; Ghosh, Bijoy K; Ulinski, Philip S

    2006-12-01

    The visual cortex of turtles contains cells with at least two different receptive field properties. Superficial units are located immediately below the pial surface. They fire in response to moving bars located anywhere in binocular visual space and to two spots of light presented with different spatiotemporal separations. Their location in the cortex suggests that superficial units correspond to a distinct class of inhibitory interneurons, the subpial cells, that are embedded in geniculocortical axons as they cross the visual cortex of turtles. This study used a detailed compartmental model of a subpial cell and a large-scale model of visual cortex to examine the cellular mechanisms that underlie the formation of superficial units on the assumption that they are subpial cells. Simulations with the detailed model indicated that the biophysical properties of subpial cells allow them to respond strongly to activation by geniculate inputs, but the presence of dendritic beads on the subpial cells decreases their sensitivity and allows them to integrate the inputs from many geniculate afferents. Simulations with the large-scale model indicated that the responses of subpial cells to simulated visual stimuli consist of two phases. A fast phase is mediated by direct geniculate inputs. A slow phase is mediated by recurrent excitation from pyramidal cells. It appears that subpial cells play a major role in controlling the information content of visual responses. PMID:17245823

  9. Testing the flexibility of the modified receptive field (MRF) theory: evidence from an unspaced orthography (Thai).

    PubMed

    Winskel, Heather; Perea, Manuel; Peart, Emma

    2014-07-01

    In the current study, we tested the generality of the modified receptive field (MRF) theory (Tydgat & Grainger, 2009) with English native speakers (Experiment 1) and Thai native speakers (Experiment 2). Thai has a distinctive alphabetic orthography with visually complex letters (ฝ ฟ or ผ พ) and nonlinear characteristics and lacks interword spaces. We used a two-alternative forced choice (2AFC) procedure to measure identification accuracy for all positions in a string of five characters, which consisted of Roman script letters, Thai letters, or symbols. For the English speakers, we found a similar pattern of results as in previous studies (i.e., a dissociation between letters and symbols). In contrast, for the Thai participants, we found that the pattern for Thai letters, Roman letters and symbols displayed a remarkably similar linear trend. Thus, while we observed qualified support for the MRF theory, in that we found an advantage for initial position, this effect also applied to symbols (i.e., our data revealed a language-specific effect). We propose that this pattern for letters and symbols in Thai has developed as a specialized adaptive mechanism for reading in this visually complex and crowded nonlinear script without interword spaces. PMID:24818534

  10. Analysis of auditory spatial receptive fields: An application of virtual auditory space technology

    NASA Astrophysics Data System (ADS)

    Takahashi, Terry T.; Keller, Clifford H.; Euston, David R.; Spezio, Michael L.

    2002-05-01

    Virtual auditory space technology, typically used to simulate acoustical environments, also allows one to vary one sound localization cue independently of others. VAST was used to determine the contributions of interaural time and level differences (ITD, ILD) to the spatial receptive fields (RFs) of neurons in the owl's midbrain. The presentation of noise filtered so that only ITD varied evoked a response along a vertical strip of virtual space, called the ITD-alone RF. Conversely, when ITD was fixed at the cell's optimum and the ILD spectrum of each location was presented, the cell responded along a horizontal strip, called the ILD-alone RF. The spatial RF was at the intersection of the ITD and ILD-alone RFs. The cell's ILD tuning across frequency, combined with individualized head-related transfer functions, was transformed into an ILD-alone RF that predicted half the variance in the measured one. This discrepancy was due partly to the poor response of the neurons to tones, and a new method of inferring frequency-specific ILD tuning from responses to noise explained about 75% of the variance. By understanding how spatial RFs are constructed, it is possible to infer the neural image of complex auditory scenes containing multiple sources and echoes. [Work supported by NIDCD.

  11. Correlations in V1 are reduced by stimulation outside the receptive field.

    PubMed

    Snyder, Adam C; Morais, Michael J; Kohn, Adam; Smith, Matthew A

    2014-08-20

    The trial-to-trial response variability of nearby cortical neurons is correlated. These correlations may strongly influence population coding performance. Numerous studies have shown that correlations can be dynamically modified by attention, adaptation, learning, and potent stimulus drive. However, the mechanisms that influence correlation strength remain poorly understood. Here we test whether correlations are influenced by presenting stimuli outside the classical receptive field (RF) of visual neurons, where they recruit a normalization signal termed surround suppression. We recorded simultaneously the activity of dozens of cells using microelectrode arrays implanted in the superficial layers of V1 in anesthetized, paralyzed macaque monkeys. We presented annular stimuli that encircled--but did not impinge upon--the RFs of the recorded cells. We found that these "extra-classical" stimuli reduced correlations in the absence of stimulation of the RF, closely resembling the decorrelating effects of stimulating the RFs directly. Our results suggest that normalization signals may be an important mechanism for modulating correlations. PMID:25143603

  12. Neurometabolic coupling differs for suppression within and beyond the classical receptive field in visual cortex

    PubMed Central

    Li, Baowang; Freeman, Ralph D

    2011-01-01

    Abstract Neurons in visual cortex exhibit two major types of stimulus elicited suppression. One, cross-orientation suppression, occurs within the classical receptive field (CRF) when an orthogonal grating is superposed on one at optimal orientation. The second, surround suppression, occurs when the size of an optimally oriented grating extends beyond the CRF. Previous proposals suggest that intracortical inhibition is responsible for surround suppression whereas feedforward processes may underlie cross-orientation suppression. To gain more insight concerning these types of suppression, we have included measurements of metabolic function in addition to neural responses. We made co-localized measurements of multiple unit neural activity and tissue oxygen concentrations in the striate cortex of anaesthetized cats while using visual stimuli to activate the two kinds of suppression. Results show that the amplitude of the initial negative oxygen response increases with stimulus size but neural responses decrease as size extends beyond the CRF. This shows that oxygen consumption increases with stimulus size regardless of reduced neural response. On the other hand, amplitudes of both the initial negative oxygen component and the neural responses are simultaneously attenuated by the orthogonal mask in cross-orientation suppression. These different neurometabolic response patterns are consistent with suggestions that the two types of suppressive processes arise from different neural mechanisms. PMID:21558164

  13. Testing the flexibility of the modified receptive field (MRF) theory: evidence from an unspaced orthography (Thai).

    PubMed

    Winskel, Heather; Perea, Manuel; Peart, Emma

    2014-07-01

    In the current study, we tested the generality of the modified receptive field (MRF) theory (Tydgat & Grainger, 2009) with English native speakers (Experiment 1) and Thai native speakers (Experiment 2). Thai has a distinctive alphabetic orthography with visually complex letters (ฝ ฟ or ผ พ) and nonlinear characteristics and lacks interword spaces. We used a two-alternative forced choice (2AFC) procedure to measure identification accuracy for all positions in a string of five characters, which consisted of Roman script letters, Thai letters, or symbols. For the English speakers, we found a similar pattern of results as in previous studies (i.e., a dissociation between letters and symbols). In contrast, for the Thai participants, we found that the pattern for Thai letters, Roman letters and symbols displayed a remarkably similar linear trend. Thus, while we observed qualified support for the MRF theory, in that we found an advantage for initial position, this effect also applied to symbols (i.e., our data revealed a language-specific effect). We propose that this pattern for letters and symbols in Thai has developed as a specialized adaptive mechanism for reading in this visually complex and crowded nonlinear script without interword spaces.

  14. [The role of the Basal Ganglia in Creating Receptive Fields in the Primary Auditory Cortex and Mechanisms of their Plasticity].

    PubMed

    Silkis, I G

    2015-01-01

    We suggest a mechanism for creating receptive fields of neurons in the primary auditory cortex (A1) and ventral part of the medial geniculate body (MGBv) in which the "direct" pathway through the basal ganglia participates. Dopamine released in the striatum in response to appearance of a sound tone promotes the induction of LTP of the efficacy of "strong" inputs and LTD of "weak" inputs from A1 to striatonigral cells due to activation of D1 receptors on these cells. Subsequent reorganization of neuronal activity in the network A1 field--basal ganglia--MGBv--A1 field results in a disinhibition of MGBv neuron activity, contrasting amplification of neural representation of a sound tone in MGBv and A1 field, and sharpening the receptive fields. Plastic shift of neuronal receptive fields is based on modification of efficacy of synaptic transmissions between the neocortex and striatum, and between all units of thalamocortical loop. Synaptic modification could be promoted by synchronization of activity of neurons which is based on the high-frequency oscillations relying on interdependent functioning of inhibitory cells in the considered loops. PMID:26506643

  15. The disinhibitory zone of the striate neuron receptive field and its sensitivity to cross-like figures.

    PubMed

    Lazareva, N A; Shevelev, I A; Novikova, R V; Tikhomirov, A S; Sharaev, G A; Tsutskiridze, D Yu

    2002-01-01

    Acute experiments on immobilized anesthetized cats were used to confirm the suggestion that the sensitivity of many neurons on the primary visual cortex to cross-shaped, angular, and Y-shaped figures may be determined by the presence within their receptive fields of disinhibitory zones, which block end-stopping inhibition. A total of 55 neurons (84 functions, i.e.. on and off responses) were used for studies of sensitivity to crosses, and responses to single bars of different lengths were compared before and after stimulation of an additional lateral zone of the field (the presumptive disinhibitory zone), which was located in terms of responses to crosses. Seventeen of the 55 cells in which increases in the length of a single bar decreased responses, i.e., which demonstrated end-stopping inhibition, showed significant increases in responses (by an average factor of 2.06 +/- 0.16) during simultaneous stimulation of the lateral zone of the receptive field, which we interpreted as a disinhibitory effect on end-stopping inhibition. These data provide the first direct evidence for the role of end-stopping inhibition and its blockade by the disinhibitory zone of the receptive field in determining the sensitivity of some neurons in the primary visual cortex of the cat to cross-shaped figures.

  16. Dynamic stimulation evokes spatially focused receptive fields in bat auditory cortex.

    PubMed

    Hoffmann, Susanne; Schuller, Gerd; Firzlaff, Uwe

    2010-01-01

    Bats can orient and hunt for prey in complete darkness using echolocation. Due to the pulse-like character of call emission they receive a stroboscopic view of their environment. During target approach, bats adjust their emitted echolocation calls to the specific requirements of the dynamically changing environmental and behavioral context. In addition to changes of the spectro-temporal call features, the spatial focusing of the beam of the sonar emissions onto the target is a conspicuous feature during target tracking. The neural processes underlying the complex sensory-motor interactions during target tracking are not well understood. In this study, we used a two-tone-pulse paradigm with 81 combinations of inter-aural intensity differences and six inter-pulse intervals in a passive hearing task to tackle the question of how transient changes in the azimuthal position of successive sounds are encoded by neurons in the auditory cortex of the bat Phyllostomus discolor. In a population of cortical neurons (11%, 24 of 217), spatial receptive fields were focused to a small region of frontal azimuthal positions during dynamic stimulation with tone-pulse pairs at short inter-pulse intervals. The response of these neurons might be important for the behaviorally observed locking of the sonar beam onto a selected target during the later stages of target tracking. Most interestingly, the majority of these neurons (88%, 21 of 24) were located in the posterior dorsal part of the auditory cortex. This cortical subfield might thus be specifically involved in the analysis of dynamic acoustic scenes.

  17. Receptive fields, geometry and conduction block of sensory neurones in the central nervous system of the leech.

    PubMed Central

    Yau, K W

    1976-01-01

    1. In segmental ganglia of the leech, the cutaneous mechanosensory neurones responding to to touch innervated the skin of their own segment and of part of the anterior and posterior adjacent segments. Each touch receptive field could be divided into three non-overlapping areas: a central part innervated by the branches of the cell which ran in the nerve roots of the ganglion containing the cell body, and anterior and posterior parts innervated by its branches which ran in the nerve roots of the anterior and posterior adjacent ganglia. 2. Impulses originating from the anterior and posterior parts of the receptive fields were susceptible to conduction block within the central nervous system when the touch cells fired repetitively at frequencies that could readily be elicited with weak mechanical stimulation. In contrast, impulses originating from the central part of the receptive fields were less susceptible to block. 3. The morphology of touch cells revealed by intracellular injection of horseradish peroxidase suggested that conduction block occurred at specific bifurcation points where small cell processes joined the main process. Different physiological experiments supported this conclusion. 4. In some touch cells, bifurcation points with particularly low safety margins of conduction operated as low-pass filters, limiting the frequency of impulses capable of invading certain branches. 5. The results suggest that mechanical stimuli which would likely be encountered by the animal can lead to conduction block within its central nervous system and as a result modify its integrative activities. PMID:1018277

  18. Visual Receptive Field Properties of Neurons in the Mouse Lateral Geniculate Nucleus

    PubMed Central

    Chakraborty, Subhojit; Schultz, Simon R.

    2016-01-01

    The lateral geniculate nucleus (LGN) is increasingly regarded as a “smart-gating” operator for processing visual information. Therefore, characterizing the response properties of LGN neurons will enable us to better understand how neurons encode and transfer visual signals. Efforts have been devoted to study its anatomical and functional features, and recent advances have highlighted the existence in rodents of complex features such as direction/orientation selectivity. However, unlike well-researched higher-order mammals such as primates, the full array of response characteristics vis-à-vis its morphological features have remained relatively unexplored in the mouse LGN. To address the issue, we recorded from mouse LGN neurons using multisite-electrode-arrays (MEAs) and analysed their discharge patterns in relation to their location under a series of visual stimulation paradigms. Several response properties paralleled results from earlier studies in the field and these include centre-surround organization, size of receptive field, spontaneous firing rate and linearity of spatial summation. However, our results also revealed “high-pass” and “low-pass” features in the temporal frequency tuning of some cells, and greater average contrast gain than reported by earlier studies. In addition, a small proportion of cells had direction/orientation selectivity. Both “high-pass” and “low-pass” cells, as well as direction and orientation selective cells, were found only in small numbers, supporting the notion that these properties emerge in the cortex. ON- and OFF-cells showed distinct contrast sensitivity and temporal frequency tuning properties, suggesting parallel projections from the retina. Incorporating a novel histological technique, we created a 3-D LGN volume model explicitly capturing the morphological features of mouse LGN and localising individual cells into anterior/middle/posterior LGN. Based on this categorization, we show that the ON

  19. Nonlinear and extra-classical receptive field properties and the statistics of natural scenes.

    PubMed

    Zetzsche, C; Röhrbein, F

    2001-08-01

    -stopping, complex-cell properties and extra-classical receptive field properties, but the 'ideal' complex cells seem only to occur with PCA. Thus, a combination of ON/OFF nonlinearities with an integrated PCA-ICA strategy seems necessary to exploit the statistical properties of natural images. PMID:11563533

  20. Does Attention Play a Role in Dynamic Receptive Field Adaptation to Changing Acoustic Salience in A1?

    PubMed Central

    Fritz, Jonathan; Elhilali, Mounya; David, Stephen; Shamma, Shihab

    2007-01-01

    Acoustic filter properties of A1 neurons can dynamically adapt to stimulus statistics, classical conditioning, instrumental learning and the changing auditory attentional focus. We have recently developed an experimental paradigm that allows us to view cortical receptive field plasticity on-line as the animal meets different behavioral challenges by attending to salient acoustic cues and changing its cortical filters to enhance performance. We propose that attention is the key trigger that initiates a cascade of events leading to the dynamic receptive field changes that we observe. In our paradigm, ferrets were initially trained, using conditioned avoidance training techniques, to discriminate between background noise stimuli (temporally orthogonal ripple combinations) and foreground tonal target stimuli. They learned to generalize the task for a wide variety of distinct background and foreground target stimuli. We recorded cortical activity in the awake behaving animal and computed on-line spectrotemporal receptive fields (STRFs) of single neurons in A1. We observed clear, predictable task-related changes in STRF shape while the animal performed spectral tasks (including single tone and multi-tone detection, and two-tone discrimination) with different tonal targets. A different set of task-related changes occurred when the animal performed temporal tasks (including gap detection and click-rate discrimination). Distinctive cortical STRF changes may constitute a “task-specific signature”. These spectral and temporal changes in cortical filters occur quite rapidly, within 2 minutes of task onset, and fade just as quickly after task completion, or in some cases, persisted for hours. The same cell could multiplex by differentially changing its receptive field in different task conditions. On-line dynamic task-related changes, as well as persistent plastic changes, were observed at a single-unit, multi-unit and population level. Auditory attention is likely to be

  1. Cardiovascular regulation by skeletal muscle reflexes in health and disease

    PubMed Central

    Murphy, Megan N.; Mizuno, Masaki; Mitchell, Jere H.

    2011-01-01

    Heart rate and blood pressure are elevated at the onset and throughout the duration of dynamic or static exercise. These neurally mediated cardiovascular adjustments to physical activity are regulated, in part, by a peripheral reflex originating in contracting skeletal muscle termed the exercise pressor reflex. Mechanically sensitive and metabolically sensitive receptors activating the exercise pressor reflex are located on the unencapsulated nerve terminals of group III and group IV afferent sensory neurons, respectively. Mechanoreceptors are stimulated by the physical distortion of their receptive fields during muscle contraction and can be sensitized by the production of metabolites generated by working skeletal myocytes. The chemical by-products of muscle contraction also stimulate metaboreceptors. Once activated, group III and IV sensory impulses are transmitted to cardiovascular control centers within the brain stem where they are integrated and processed. Activation of the reflex results in an increase in efferent sympathetic nerve activity and a withdrawal of parasympathetic nerve activity. These actions result in the precise alterations in cardiovascular hemodynamics requisite to meet the metabolic demands of working skeletal muscle. Coordinated activity by this reflex is altered after the development of cardiovascular disease, generating exaggerated increases in sympathetic nerve activity, blood pressure, heart rate, and vascular resistance. The basic components and operational characteristics of the reflex, the techniques used in human and animals to study the reflex, and the emerging evidence describing the dysfunction of the reflex with the advent of cardiovascular disease are highlighted in this review. PMID:21841019

  2. Möbius-strip-like columnar functional connections are revealed in somato-sensory receptive field centroids

    PubMed Central

    Wright, James Joseph; Bourke, Paul David; Favorov, Oleg Vyachesslavovich

    2014-01-01

    Receptive fields of neurons in the forelimb region of areas 3b and 1 of primary somatosensory cortex, in cats and monkeys, were mapped using extracellular recordings obtained sequentially from nearly radial penetrations. Locations of the field centroids indicated the presence of a functional system in which cortical homotypic representations of the limb surfaces are entwined in three-dimensional Möbius-strip-like patterns of synaptic connections. Boundaries of somatosensory receptive field in nested groups irregularly overlie the centroid order, and are interpreted as arising from the superposition of learned connections upon the embryonic order. Since the theory of embryonic synaptic self-organization used to model these results was devised and earlier used to explain findings in primary visual cortex, the present findings suggest the theory may be of general application throughout cortex and may reveal a modular functional synaptic system, which, only in some parts of the cortex, and in some species, is manifest as anatomical ordering into columns. PMID:25400552

  3. Reversible deactivation of higher-order posterior parietal areas. I. Alterations of receptive field characteristics in early stages of neocortical processing

    PubMed Central

    Cooke, Dylan F.; Goldring, Adam B.; Baldwin, Mary K. L.; Recanzone, Gregg H.; Chen, Arnold; Pan, Tingrui; Simon, Scott I.

    2014-01-01

    Somatosensory processing in the anesthetized macaque monkey was examined by reversibly deactivating posterior parietal areas 5L and 7b and motor/premotor cortex (M1/PM) with microfluidic thermal regulators developed by our laboratories. We examined changes in receptive field size and configuration for neurons in areas 1 and 2 that occurred during and after cooling deactivation. Together the deactivated fields and areas 1 and 2 form part of a network for reaching and grasping in human and nonhuman primates. Cooling area 7b had a dramatic effect on receptive field size for neurons in areas 1 and 2, while cooling area 5 had moderate effects and cooling M1/PM had little effect. Specifically, cooling discrete locations in 7b resulted in expansions of the receptive fields for neurons in areas 1 and 2 that were greater in magnitude and occurred in a higher proportion of sites than similar changes evoked by cooling the other fields. At some sites, the neural receptive field returned to the precooling configuration within 5–22 min of rewarming, but at other sites changes in receptive fields persisted. These results indicate that there are profound top-down influences on sensory processing of early cortical areas in the somatosensory cortex. PMID:25143546

  4. Reducing contralateral SI activity reveals hindlimb receptive fields in the SI forelimb-stump representation of neonatally amputated rats.

    PubMed

    Pluto, Charles P; Chiaia, Nicolas L; Rhoades, Robert W; Lane, Richard D

    2005-09-01

    In adult rats that sustained forelimb amputation on the day of birth, >30% of multiunit recording sites in the forelimb-stump representation of primary somatosensory cortex (SI) also respond to cutaneous hindlimb stimulation when cortical GABA(A+B) receptors are blocked (GRB). This study examined whether hindlimb receptive fields could also be revealed in forelimb-stump sites by reducing one known source of excitatory input to SI GABAergic neurons, the contralateral SI cortex. Corpus callosum projection neurons connect homotopic SI regions, making excitatory contacts onto pyramidal cells and interneurons. Thus in addition to providing monosynaptic excitation in SI, callosal fibers can produce disynaptic inhibition through excitatory synapses with inhibitory interneurons. Based on the latter of these connections, we hypothesized that inactivating the contralateral (intact) SI forelimb region would "unmask" normally suppressed hindlimb responses by reducing the activity of SI GABAergic neurons. The SI forelimb-stump representation was first mapped under normal conditions and then during GRB to identify stump/hindlimb responsive sites. After GRB had dissipated, the contralateral (intact) SI forelimb region was mapped and reversibly inactivated with injections of 4% lidocaine, and selected forelimb-stump sites were retested. Contralateral SI inactivation revealed hindlimb responses in approximately 60% of sites that were stump/hindlimb responsive during GRB. These findings indicate that activity in the contralateral SI contributes to the suppression of reorganized hindlimb receptive fields in neonatally amputated rats.

  5. The menace reflex.

    PubMed

    van Ballegoij, Wouter J C; Koehler, Peter J; Meulen, Bastiaan C Ter

    2015-06-01

    The menace reflex (blink reflex to visual threat) tests visual processing at the bedside in patients who cannot participate in normal visual field testing. We reviewed a collection of recently discovered historical movies showing the experiments of the Dutch physiologist Gysbertus Rademaker (1887-1957), exploring the anatomy of this reflex by making cerebral lesions in dogs. The experiments show not only that the menace reflex is cortically mediated, but also that lesions outside the visual cortex can abolish the reflex. Therefore, although often erroneously used in this way, an absent menace does not always indicate a visual field deficit.

  6. The menace reflex.

    PubMed

    van Ballegoij, Wouter J C; Koehler, Peter J; Meulen, Bastiaan C Ter

    2015-06-01

    The menace reflex (blink reflex to visual threat) tests visual processing at the bedside in patients who cannot participate in normal visual field testing. We reviewed a collection of recently discovered historical movies showing the experiments of the Dutch physiologist Gysbertus Rademaker (1887-1957), exploring the anatomy of this reflex by making cerebral lesions in dogs. The experiments show not only that the menace reflex is cortically mediated, but also that lesions outside the visual cortex can abolish the reflex. Therefore, although often erroneously used in this way, an absent menace does not always indicate a visual field deficit. PMID:25670870

  7. [Conditioned feedback and inhibitory reorganization of the receptive fields of the cortical neurons as a basis for the subconscious change in the thresholds of visual recognition and detection].

    PubMed

    Shevelev, I A

    1990-01-01

    In the paper three groups of facts are compared: significant adaptative and adaptational modification of receptive fields of cat's visual cortex neurones, conditioned selective subsensory change of the threshold of perception (detection and recognition) of a letter by man in relation to two control ones and the role of spatially specialized cortical inhibition in formation and adaptative modifications of receptive fields and detector properties of the visual cortex neurones. Interconnection is discussed of the phenomena described as well as community of their mechanisms. PMID:1964326

  8. Receptive-field size of S1 cortical neurones is altered by methaqualone via a GABA mechanism.

    PubMed

    Hicks, T P; Kaneko, T; Oka, J I

    1990-02-01

    Methaqualone (Mtq; quaaludes or 'ludes) is a controlled substance, having a molecular structure related to the imidiazobenzodiazepine series of drugs, that has gained some notoriety recently due to its history of widespread abuse on the street. Users report experiencing peripheral paresthesia and transient numbness on body parts receiving dense cutaneous innervation (lips, fingertips, etc.). Since the receptive-field (RF)-sizes of many primary somatosensory (S1) cortical neurones are controlled by local, gamma-aminobutyric acid (GABA)-mediated inhibitory processes, we tested Mtq to see whether its clinical symptoms might have a basis in an action through central GABA-mediated synaptic processes. This report supports this contention and describes a likely pharmacological mechanism involved as one being related to the Ro 15-1788-sensitive benzodiazepine (Bzd) recognition site(s) of the GABA receptor complex. PMID:2311013

  9. Receptive-field size of S1 cortical neurones is altered by methaqualone via a GABA mechanism.

    PubMed

    Hicks, T P; Kaneko, T; Oka, J I

    1990-02-01

    Methaqualone (Mtq; quaaludes or 'ludes) is a controlled substance, having a molecular structure related to the imidiazobenzodiazepine series of drugs, that has gained some notoriety recently due to its history of widespread abuse on the street. Users report experiencing peripheral paresthesia and transient numbness on body parts receiving dense cutaneous innervation (lips, fingertips, etc.). Since the receptive-field (RF)-sizes of many primary somatosensory (S1) cortical neurones are controlled by local, gamma-aminobutyric acid (GABA)-mediated inhibitory processes, we tested Mtq to see whether its clinical symptoms might have a basis in an action through central GABA-mediated synaptic processes. This report supports this contention and describes a likely pharmacological mechanism involved as one being related to the Ro 15-1788-sensitive benzodiazepine (Bzd) recognition site(s) of the GABA receptor complex.

  10. Space-time codependence of retinal ganglion cells can be explained by novel and separable components of their receptive fields.

    PubMed

    Cowan, Cameron S; Sabharwal, Jasdeep; Wu, Samuel M

    2016-09-01

    Reverse correlation methods such as spike-triggered averaging consistently identify the spatial center in the linear receptive fields (RFs) of retinal ganglion cells (GCs). However, the spatial antagonistic surround observed in classical experiments has proven more elusive. Tests for the antagonistic surround have heretofore relied on models that make questionable simplifying assumptions such as space-time separability and radial homogeneity/symmetry. We circumvented these, along with other common assumptions, and observed a linear antagonistic surround in 754 of 805 mouse GCs. By characterizing the RF's space-time structure, we found the overall linear RF's inseparability could be accounted for both by tuning differences between the center and surround and differences within the surround. Finally, we applied this approach to characterize spatial asymmetry in the RF surround. These results shed new light on the spatiotemporal organization of GC linear RFs and highlight a major contributor to its inseparability. PMID:27604400

  11. Space-time codependence of retinal ganglion cells can be explained by novel and separable components of their receptive fields.

    PubMed

    Cowan, Cameron S; Sabharwal, Jasdeep; Wu, Samuel M

    2016-09-01

    Reverse correlation methods such as spike-triggered averaging consistently identify the spatial center in the linear receptive fields (RFs) of retinal ganglion cells (GCs). However, the spatial antagonistic surround observed in classical experiments has proven more elusive. Tests for the antagonistic surround have heretofore relied on models that make questionable simplifying assumptions such as space-time separability and radial homogeneity/symmetry. We circumvented these, along with other common assumptions, and observed a linear antagonistic surround in 754 of 805 mouse GCs. By characterizing the RF's space-time structure, we found the overall linear RF's inseparability could be accounted for both by tuning differences between the center and surround and differences within the surround. Finally, we applied this approach to characterize spatial asymmetry in the RF surround. These results shed new light on the spatiotemporal organization of GC linear RFs and highlight a major contributor to its inseparability.

  12. Receptive Field Vectors of Genetically-Identified Retinal Ganglion Cells Reveal Cell-Type-Dependent Visual Functions

    PubMed Central

    Katz, Matthew L.; Viney, Tim J.; Nikolic, Konstantin

    2016-01-01

    Sensory stimuli are encoded by diverse kinds of neurons but the identities of the recorded neurons that are studied are often unknown. We explored in detail the firing patterns of eight previously defined genetically-identified retinal ganglion cell (RGC) types from a single transgenic mouse line. We first introduce a new technique of deriving receptive field vectors (RFVs) which utilises a modified form of mutual information (“Quadratic Mutual Information”). We analysed the firing patterns of RGCs during presentation of short duration (~10 second) complex visual scenes (natural movies). We probed the high dimensional space formed by the visual input for a much smaller dimensional subspace of RFVs that give the most information about the response of each cell. The new technique is very efficient and fast and the derivation of novel types of RFVs formed by the natural scene visual input was possible even with limited numbers of spikes per cell. This approach enabled us to estimate the 'visual memory' of each cell type and the corresponding receptive field area by calculating Mutual Information as a function of the number of frames and radius. Finally, we made predictions of biologically relevant functions based on the RFVs of each cell type. RGC class analysis was complemented with results for the cells’ response to simple visual input in the form of black and white spot stimulation, and their classification on several key physiological metrics. Thus RFVs lead to predictions of biological roles based on limited data and facilitate analysis of sensory-evoked spiking data from defined cell types. PMID:26845435

  13. Spatial receptive fields in the retina and dorsal lateral geniculate nucleus of mice lacking rods and cones.

    PubMed

    Procyk, Christopher A; Eleftheriou, Cyril G; Storchi, Riccardo; Allen, Annette E; Milosavljevic, Nina; Brown, Timothy M; Lucas, Robert J

    2015-08-01

    In advanced retinal degeneration loss of rods and cones leaves melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) as the only source of visual information. ipRGCs drive non-image-forming responses (e.g., circadian photoentrainment) under such conditions but, despite projecting to the primary visual thalamus [dorsal lateral geniculate nucleus (dLGN)], do not support form vision. We wished to determine what precludes ipRGCs supporting spatial discrimination after photoreceptor loss, using a mouse model (rd/rd cl) lacking rods and cones. Using multielectrode arrays, we found that both RGCs and neurons in the dLGN of this animal have clearly delineated spatial receptive fields. In the retina, they are typically symmetrical, lack inhibitory surrounds, and have diameters in the range of 10-30° of visual space. Receptive fields in the dLGN were larger (diameters typically 30-70°) but matched the retinotopic map of the mouse dLGN. Injections of a neuroanatomical tracer (cholera toxin β-subunit) into the dLGN confirmed that retinotopic order of ganglion cell projections to the dLGN and thalamic projections to the cortex is at least superficially intact in rd/rd cl mice. However, as previously reported for deafferented ipRGCs, onset and offset of light responses have long latencies in the rd/rd cl retina and dLGN. Accordingly, dLGN neurons failed to track dynamic changes in light intensity in this animal. Our data reveal that ipRGCs can convey spatial information in advanced retinal degeneration and identify their poor temporal fidelity as the major limitation in their ability to provide information about spatial patterns under natural viewing conditions. PMID:26084909

  14. Receptive field properties of bipolar cell axon terminals in direction-selective sublaminas of the mouse retina

    PubMed Central

    Chen, Minggang; Lee, Seunghoon; Park, Silvia J. H.; Looger, Loren L.

    2014-01-01

    Retinal bipolar cells (BCs) transmit visual signals in parallel channels from the outer to the inner retina, where they provide glutamatergic inputs to specific networks of amacrine and ganglion cells. Intricate network computation at BC axon terminals has been proposed as a mechanism for complex network computation, such as direction selectivity, but direct knowledge of the receptive field property and the synaptic connectivity of the axon terminals of various BC types is required in order to understand the role of axonal computation by BCs. The present study tested the essential assumptions of the presynaptic model of direction selectivity at axon terminals of three functionally distinct BC types that ramify in the direction-selective strata of the mouse retina. Results from two-photon Ca2+ imaging, optogenetic stimulation, and dual patch-clamp recording demonstrated that 1) CB5 cells do not receive fast GABAergic synaptic feedback from starburst amacrine cells (SACs); 2) light-evoked and spontaneous Ca2+ responses are well coordinated among various local regions of CB5 axon terminals; 3) CB5 axon terminals are not directionally selective; 4) CB5 cells consist of two novel functional subtypes with distinct receptive field structures; 5) CB7 cells provide direct excitatory synaptic inputs to, but receive no direct GABAergic synaptic feedback from, SACs; and 6) CB7 axon terminals are not directionally selective, either. These findings help to simplify models of direction selectivity by ruling out complex computation at BC terminals. They also show that CB5 comprises two functional subclasses of BCs. PMID:25031256

  15. Spatial receptive fields in the retina and dorsal lateral geniculate nucleus of mice lacking rods and cones

    PubMed Central

    Procyk, Christopher A.; Eleftheriou, Cyril G.; Storchi, Riccardo; Allen, Annette E.; Milosavljevic, Nina; Brown, Timothy M.

    2015-01-01

    In advanced retinal degeneration loss of rods and cones leaves melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) as the only source of visual information. ipRGCs drive non-image-forming responses (e.g., circadian photoentrainment) under such conditions but, despite projecting to the primary visual thalamus [dorsal lateral geniculate nucleus (dLGN)], do not support form vision. We wished to determine what precludes ipRGCs supporting spatial discrimination after photoreceptor loss, using a mouse model (rd/rd cl) lacking rods and cones. Using multielectrode arrays, we found that both RGCs and neurons in the dLGN of this animal have clearly delineated spatial receptive fields. In the retina, they are typically symmetrical, lack inhibitory surrounds, and have diameters in the range of 10–30° of visual space. Receptive fields in the dLGN were larger (diameters typically 30–70°) but matched the retinotopic map of the mouse dLGN. Injections of a neuroanatomical tracer (cholera toxin β-subunit) into the dLGN confirmed that retinotopic order of ganglion cell projections to the dLGN and thalamic projections to the cortex is at least superficially intact in rd/rd cl mice. However, as previously reported for deafferented ipRGCs, onset and offset of light responses have long latencies in the rd/rd cl retina and dLGN. Accordingly, dLGN neurons failed to track dynamic changes in light intensity in this animal. Our data reveal that ipRGCs can convey spatial information in advanced retinal degeneration and identify their poor temporal fidelity as the major limitation in their ability to provide information about spatial patterns under natural viewing conditions. PMID:26084909

  16. [Reflexes, instincts, emotions and passions].

    PubMed

    Sánchez, Alberto Portera

    2008-01-01

    In animals of the same species, the reflexes, having evolved similarly, in a few milliseconds, automatically activate the corresponding reflex arch and without the intervention of the animal generate the adequate response: medullary, mesencephalic or trans-hemispheric. These neurophysiological functions have allowed the animals to be free from predators and increasy their longevity and, as a consequence, the appearance of numerous species during millions of years. A further step in the reflexes evolution, the instincts emerged and their activity, a result of neuro-hormonal functions, stimulates the male's sexual appetite when the females are receptive for their copulation and fecundation. PMID:18924359

  17. [Effectiveness of perforated film mulching on maize field in rainfall reception and soil ventilation].

    PubMed

    Chi, Baoliang; Huang, Xuefang; Zhang, Dongmei

    2006-04-01

    To improve the light rain availability and soil ventilation in semi-arid area, this paper studied the effectiveness of perforated plastic film mulching on maize field. The results showed that perforated plastic film mulching had the benefits of receiving rainfall and supplementing soil moisture. Soil CO2 content increased with increasing area of mulching, and was lower under perforated plastic film mulching than under common plastic film mulching. A negative correlation was observed between maize root vitality and soil CO2 content. The maize yield under perforated film mulching was 8.98% higher than that under common film mulching.

  18. The Length of Henle Fibers in the Human Retina and a Model of Ganglion Receptive Field Density in the Visual Field

    PubMed Central

    Drasdo, Neville; Millican, C. Leigh; Katholi, Charles R.; Curcio, Christine A.

    2007-01-01

    An experimental study of lateral displacement of ganglion cells (GCs) from foveal cones in six human retinas is reported. At 406–675 μm in length, as measured in radially oriented cross-sections, Henle fibers are substantially longer than previously reported. However, a new theoretical model indicates that the discrepancies in these reports are mainly due to meridional differences. The model takes into account the effects of optical degradation and peripheral ON/OFF asymmetry and predicts a central GC:cone ratio of 2.24:1. It provides estimates of cumulative counts and GC receptive field density at 0°–30° along the principal meridians of the visual field. PMID:17320143

  19. Learning to reach by reinforcement learning using a receptive field based function approximation approach with continuous actions.

    PubMed

    Tamosiunaite, Minija; Asfour, Tamim; Wörgötter, Florentin

    2009-03-01

    Reinforcement learning methods can be used in robotics applications especially for specific target-oriented problems, for example the reward-based recalibration of goal directed actions. To this end still relatively large and continuous state-action spaces need to be efficiently handled. The goal of this paper is, thus, to develop a novel, rather simple method which uses reinforcement learning with function approximation in conjunction with different reward-strategies for solving such problems. For the testing of our method, we use a four degree-of-freedom reaching problem in 3D-space simulated by a two-joint robot arm system with two DOF each. Function approximation is based on 4D, overlapping kernels (receptive fields) and the state-action space contains about 10,000 of these. Different types of reward structures are being compared, for example, reward-on- touching-only against reward-on-approach. Furthermore, forbidden joint configurations are punished. A continuous action space is used. In spite of a rather large number of states and the continuous action space these reward/punishment strategies allow the system to find a good solution usually within about 20 trials. The efficiency of our method demonstrated in this test scenario suggests that it might be possible to use it on a real robot for problems where mixed rewards can be defined in situations where other types of learning might be difficult. PMID:19229556

  20. Push-Pull Receptive Field Organization and Synaptic Depression: Mechanisms for Reliably Encoding Naturalistic Stimuli in V1

    PubMed Central

    Kremkow, Jens; Perrinet, Laurent U.; Monier, Cyril; Alonso, Jose-Manuel; Aertsen, Ad; Frégnac, Yves; Masson, Guillaume S.

    2016-01-01

    Neurons in the primary visual cortex are known for responding vigorously but with high variability to classical stimuli such as drifting bars or gratings. By contrast, natural scenes are encoded more efficiently by sparse and temporal precise spiking responses. We used a conductance-based model of the visual system in higher mammals to investigate how two specific features of the thalamo-cortical pathway, namely push-pull receptive field organization and fast synaptic depression, can contribute to this contextual reshaping of V1 responses. By comparing cortical dynamics evoked respectively by natural vs. artificial stimuli in a comprehensive parametric space analysis, we demonstrate that the reliability and sparseness of the spiking responses during natural vision is not a mere consequence of the increased bandwidth in the sensory input spectrum. Rather, it results from the combined impacts of fast synaptic depression and push-pull inhibition, the later acting for natural scenes as a form of “effective” feed-forward inhibition as demonstrated in other sensory systems. Thus, the combination of feedforward-like inhibition with fast thalamo-cortical synaptic depression by simple cells receiving a direct structured input from thalamus composes a generic computational mechanism for generating a sparse and reliable encoding of natural sensory events. PMID:27242445

  1. Differences between Spectro-Temporal Receptive Fields Derived from Artificial and Natural Stimuli in the Auditory Cortex

    PubMed Central

    Laudanski, Jonathan; Edeline, Jean-Marc; Huetz, Chloé

    2012-01-01

    Spectro-temporal properties of auditory cortex neurons have been extensively studied with artificial sounds but it is still unclear whether they help in understanding neuronal responses to communication sounds. Here, we directly compared spectro-temporal receptive fields (STRFs) obtained from the same neurons using both artificial stimuli (dynamic moving ripples, DMRs) and natural stimuli (conspecific vocalizations) that were matched in terms of spectral content, average power and modulation spectrum. On a population of auditory cortex neurons exhibiting reliable tuning curves when tested with pure tones, significant STRFs were obtained for 62% of the cells with vocalizations and 68% with DMR. However, for many cells with significant vocalization-derived STRFs (STRFvoc) and DMR-derived STRFs (STRFdmr), the BF, latency, bandwidth and global STRFs shape differed more than what would be predicted by spiking responses simulated by a linear model based on a non-homogenous Poisson process. Moreover STRFvoc predicted neural responses to vocalizations more accurately than STRFdmr predicted neural response to DMRs, despite similar spike-timing reliability for both sets of stimuli. Cortical bursts, which potentially introduce nonlinearities in evoked responses, did not explain the differences between STRFvoc and STRFdmr. Altogether, these results suggest that the nonlinearity of auditory cortical responses makes it difficult to predict responses to communication sounds from STRFs computed from artificial stimuli. PMID:23209771

  2. Rearrangement of receptive field topography after intracortical and peripheral stimulation: the role of plasticity in inhibitory pathways.

    PubMed

    Kalarickal, George J; Marshall, Jonathan A

    2002-02-01

    Intracortical microstimulation (ICMS) of a single site in the somatosensory cortex of rats and monkeys for 2-6 h increases the number of neurons responsive to the skin region corresponding to the ICMS-site receptive field (RF), with very little effect on the position and size of the ICMS-site RF, and the response evoked at the ICMS site by tactile stimulation. Large changes in RF topography are also observed following several weeks of repetitive stimulation of a restricted skin region during tactile frequency discrimination training in monkeys. It has been suggested that these changes in RF topography are caused by competitive learning in excitatory pathways. This paper analyses the possible role of lateral inhibitory synaptic plasticity in producing cortical plasticity after ICMS and peripheral conditioning in adult animals. The 'EXIN' (afferent excitatory and lateral inhibitory) synaptic plasticity rules are used to model RF changes after ICMS and peripheral stimulation. The EXIN model produces RF topographical changes similar to those observed experimentally. It is shown that lateral inhibitory pathway plasticity is sufficient to model RF changes and increase in position discrimination after peripheral stimulation. Several novel and testable predictions are made based on the EXIN model.

  3. Push-Pull Receptive Field Organization and Synaptic Depression: Mechanisms for Reliably Encoding Naturalistic Stimuli in V1.

    PubMed

    Kremkow, Jens; Perrinet, Laurent U; Monier, Cyril; Alonso, Jose-Manuel; Aertsen, Ad; Frégnac, Yves; Masson, Guillaume S

    2016-01-01

    Neurons in the primary visual cortex are known for responding vigorously but with high variability to classical stimuli such as drifting bars or gratings. By contrast, natural scenes are encoded more efficiently by sparse and temporal precise spiking responses. We used a conductance-based model of the visual system in higher mammals to investigate how two specific features of the thalamo-cortical pathway, namely push-pull receptive field organization and fast synaptic depression, can contribute to this contextual reshaping of V1 responses. By comparing cortical dynamics evoked respectively by natural vs. artificial stimuli in a comprehensive parametric space analysis, we demonstrate that the reliability and sparseness of the spiking responses during natural vision is not a mere consequence of the increased bandwidth in the sensory input spectrum. Rather, it results from the combined impacts of fast synaptic depression and push-pull inhibition, the later acting for natural scenes as a form of "effective" feed-forward inhibition as demonstrated in other sensory systems. Thus, the combination of feedforward-like inhibition with fast thalamo-cortical synaptic depression by simple cells receiving a direct structured input from thalamus composes a generic computational mechanism for generating a sparse and reliable encoding of natural sensory events. PMID:27242445

  4. Sparse Spectro-Temporal Receptive Fields Based on Multi-Unit and High-Gamma Responses in Human Auditory Cortex

    PubMed Central

    Jenison, Rick L.; Reale, Richard A.; Armstrong, Amanda L.; Oya, Hiroyuki; Kawasaki, Hiroto; Howard, Matthew A.

    2015-01-01

    Spectro-Temporal Receptive Fields (STRFs) were estimated from both multi-unit sorted clusters and high-gamma power responses in human auditory cortex. Intracranial electrophysiological recordings were used to measure responses to a random chord sequence of Gammatone stimuli. Traditional methods for estimating STRFs from single-unit recordings, such as spike-triggered-averages, tend to be noisy and are less robust to other response signals such as local field potentials. We present an extension to recently advanced methods for estimating STRFs from generalized linear models (GLM). A new variant of regression using regularization that penalizes non-zero coefficients is described, which results in a sparse solution. The frequency-time structure of the STRF tends toward grouping in different areas of frequency-time and we demonstrate that group sparsity-inducing penalties applied to GLM estimates of STRFs reduces the background noise while preserving the complex internal structure. The contribution of local spiking activity to the high-gamma power signal was factored out of the STRF using the GLM method, and this contribution was significant in 85 percent of the cases. Although the GLM methods have been used to estimate STRFs in animals, this study examines the detailed structure directly from auditory cortex in the awake human brain. We used this approach to identify an abrupt change in the best frequency of estimated STRFs along posteromedial-to-anterolateral recording locations along the long axis of Heschl’s gyrus. This change correlates well with a proposed transition from core to non-core auditory fields previously identified using the temporal response properties of Heschl’s gyrus recordings elicited by click-train stimuli. PMID:26367010

  5. Rapid mapping of visual receptive fields by filtered back projection: application to multi-neuronal electrophysiology and imaging.

    PubMed

    Johnston, Jamie; Ding, Huayu; Seibel, Sofie H; Esposti, Federico; Lagnado, Leon

    2014-11-15

    Neurons in the visual system vary widely in the spatiotemporal properties of their receptive fields (RFs), and understanding these variations is key to elucidating how visual information is processed. We present a new approach for mapping RFs based on the filtered back projection (FBP), an algorithm used for tomographic reconstructions. To estimate RFs, a series of bars were flashed across the retina at pseudo-random positions and at a minimum of five orientations. We apply this method to retinal neurons and show that it can accurately recover the spatial RF and impulse response of ganglion cells recorded on a multi-electrode array. We also demonstrate its utility for in vivo imaging by mapping the RFs of an array of bipolar cell synapses expressing a genetically encoded Ca(2+) indicator. We find that FBP offers several advantages over the commonly used spike-triggered average (STA): (i) ON and OFF components of a RF can be separated; (ii) the impulse response can be reconstructed at sample rates of 125 Hz, rather than the refresh rate of a monitor; (iii) FBP reveals the response properties of neurons that are not evident using STA, including those that display orientation selectivity, or fire at low mean spike rates; and (iv) the FBP method is fast, allowing the RFs of all the bipolar cell synaptic terminals in a field of view to be reconstructed in under 4 min. Use of the FBP will benefit investigations of the visual system that employ electrophysiology or optical reporters to measure activity across populations of neurons. PMID:25172952

  6. Emulating the visual receptive-field properties of MST neurons with a template model of heading estimation

    NASA Technical Reports Server (NTRS)

    Perrone, J. A.; Stone, L. S.

    1998-01-01

    We have proposed previously a computational neural-network model by which the complex patterns of retinal image motion generated during locomotion (optic flow) can be processed by specialized detectors acting as templates for specific instances of self-motion. The detectors in this template model respond to global optic flow by sampling image motion over a large portion of the visual field through networks of local motion sensors with properties similar to those of neurons found in the middle temporal (MT) area of primate extrastriate visual cortex. These detectors, arranged within cortical-like maps, were designed to extract self-translation (heading) and self-rotation, as well as the scene layout (relative distances) ahead of a moving observer. We then postulated that heading from optic flow is directly encoded by individual neurons acting as heading detectors within the medial superior temporal (MST) area. Others have questioned whether individual MST neurons can perform this function because some of their receptive-field properties seem inconsistent with this role. To resolve this issue, we systematically compared MST responses with those of detectors from two different configurations of the model under matched stimulus conditions. We found that the characteristic physiological properties of MST neurons can be explained by the template model. We conclude that MST neurons are well suited to support self-motion estimation via a direct encoding of heading and that the template model provides an explicit set of testable hypotheses that can guide future exploration of MST and adjacent areas within the superior temporal sulcus.

  7. Rapid mapping of visual receptive fields by filtered back projection: application to multi-neuronal electrophysiology and imaging.

    PubMed

    Johnston, Jamie; Ding, Huayu; Seibel, Sofie H; Esposti, Federico; Lagnado, Leon

    2014-11-15

    Neurons in the visual system vary widely in the spatiotemporal properties of their receptive fields (RFs), and understanding these variations is key to elucidating how visual information is processed. We present a new approach for mapping RFs based on the filtered back projection (FBP), an algorithm used for tomographic reconstructions. To estimate RFs, a series of bars were flashed across the retina at pseudo-random positions and at a minimum of five orientations. We apply this method to retinal neurons and show that it can accurately recover the spatial RF and impulse response of ganglion cells recorded on a multi-electrode array. We also demonstrate its utility for in vivo imaging by mapping the RFs of an array of bipolar cell synapses expressing a genetically encoded Ca(2+) indicator. We find that FBP offers several advantages over the commonly used spike-triggered average (STA): (i) ON and OFF components of a RF can be separated; (ii) the impulse response can be reconstructed at sample rates of 125 Hz, rather than the refresh rate of a monitor; (iii) FBP reveals the response properties of neurons that are not evident using STA, including those that display orientation selectivity, or fire at low mean spike rates; and (iv) the FBP method is fast, allowing the RFs of all the bipolar cell synaptic terminals in a field of view to be reconstructed in under 4 min. Use of the FBP will benefit investigations of the visual system that employ electrophysiology or optical reporters to measure activity across populations of neurons.

  8. Feedback to distal dendrites links fMRI signals to neural receptive fields in a spiking network model of the visual cortex.

    PubMed

    Heikkinen, Hanna; Sharifian, Fariba; Vigario, Ricardo; Vanni, Simo

    2015-07-01

    The blood oxygenation level-dependent (BOLD) response has been strongly associated with neuronal activity in the brain. However, some neuronal tuning properties are consistently different from the BOLD response. We studied the spatial extent of neural and hemodynamic responses in the primary visual cortex, where the BOLD responses spread and interact over much longer distances than the small receptive fields of individual neurons would predict. Our model shows that a feedforward-feedback loop between V1 and a higher visual area can account for the observed spread of the BOLD response. In particular, anisotropic landing of inputs to compartmental neurons were necessary to account for the BOLD signal spread, while retaining realistic spiking responses. Our work shows that simple dendrites can separate tuning at the synapses and at the action potential output, thus bridging the BOLD signal to the neural receptive fields with high fidelity.

  9. Tactile orientation perception: an ideal observer analysis of human psychophysical performance in relation to macaque area 3b receptive fields.

    PubMed

    Peters, Ryan M; Staibano, Phillip; Goldreich, Daniel

    2015-12-01

    The ability to resolve the orientation of edges is crucial to daily tactile and sensorimotor function, yet the means by which edge perception occurs is not well understood. Primate cortical area 3b neurons have diverse receptive field (RF) spatial structures that may participate in edge orientation perception. We evaluated five candidate RF models for macaque area 3b neurons, previously recorded while an oriented bar contacted the monkey's fingertip. We used a Bayesian classifier to assign each neuron a best-fit RF structure. We generated predictions for human performance by implementing an ideal observer that optimally decoded stimulus-evoked spike counts in the model neurons. The ideal observer predicted a saturating reduction in bar orientation discrimination threshold with increasing bar length. We tested 24 humans on an automated, precision-controlled bar orientation discrimination task and observed performance consistent with that predicted. We next queried the ideal observer to discover the RF structure and number of cortical neurons that best matched each participant's performance. Human perception was matched with a median of 24 model neurons firing throughout a 1-s period. The 10 lowest-performing participants were fit with RFs lacking inhibitory sidebands, whereas 12 of the 14 higher-performing participants were fit with RFs containing inhibitory sidebands. Participants whose discrimination improved as bar length increased to 10 mm were fit with longer RFs; those who performed well on the 2-mm bar, with narrower RFs. These results suggest plausible RF features and computational strategies underlying tactile spatial perception and may have implications for perceptual learning.

  10. Suppression of contour perception by band-limited noise and its relation to nonclassical receptive field inhibition.

    PubMed

    Petkov, Nicolai; Westenberg, Michel A

    2003-03-01

    Band-spectrum noise has been shown to suppress the visual perception of printed letters. The suppression exhibits a specific dependence on the spatial frequency of the noise, and the frequency domain of most effective inhibition has been related to the size of the letters. In this paper, we address two important questions that were left open by previous studies: (1) Is the observed effect specific to text, and which parameters determine the domain of most effective suppression? (2) What is the origin of the effect in terms of underlying neural processes? We conduct a series of psychophysical experiments that demonstrate that the frequency domain of most effective inhibition depends on the stroke width of the letter rather than on the letter size. These experiments also demonstrate that the effect is not specific to the recognition of letters but also applies to other objects and even to single bars. We attribute the observed effect to nonclassical receptive field (non-CRF) inhibition in visual area V1. This mechanism has previously been suggested as the possible origin of various other perceptual effects. We introduce computational models of two types of cell that incorporate non-CRF inhibition, which are based on Gabor energy filters extended by surround suppression of two kinds: isotropic and anisotropic. The computational models confirm previous qualitative explanations of perceptual effects, such as orientation contrast pop-out, reduced saliency of lines embedded in gratings, and reduced saliency of contours surrounded by textures. We apply the computational models to the images used in the psychophysical experiments. The computational results show a dependence of the inhibition effect on the spatial frequency of the noise that is similar to the suppression effect measured in the psychophysical experiments. The experimental results and their explanation give further support to the idea of a possible functional role of non-CRF inhibition in the separation of

  11. GlyRα2, not GlyRα3, modulates the receptive field surround of OFF retinal ganglion cells.

    PubMed

    Zhang, Chi; Nobles, Regina D; McCall, Maureen A

    2015-01-01

    Receptive fields (RFs) of most retinal ganglion cells (RGCs) consist of an excitatory center and suppressive surround. The RF center arises from the summation of excitatory bipolar cell glutamatergic inputs, whereas the surround arises from lateral inhibitory inputs. In the retina, both gamma amino butyric acid (GABA) and glycine are inhibitory neurotransmitters. A clear role for GABAergic inhibition modulating the RGC RF surround has been demonstrated across species. Glycinergic inhibition is more commonly associated with RF center modulation, although there is some evidence that it may contribute to the RF surround. The synaptic glycinergic chloride channels are formed by three homomeric β and two homomeric α subunits that can be glycine receptor (GlyR) α1, α2, α3, or α4. GlyRα composition is responsible for currents with distinct decay kinetics. Their expression within the inner plexiform laminae and neuronal subtypes also differ. We studied the role of GlyR subunit selective modulation of RGC RF surrounds, using mice lacking GlyRα2 (Glra2 -/-), GlyRα3 (Glra3 -/-), or both (Glra2/3 -/-). We chose this molecular genetic approach instead of pharmacological manipulation because there are no subunit selective antagonists and strychnine blocks all GlyRs. Comparisons of annulus-evoked responses among wild type (WT) and GlyRα knockouts (Glra2 -/-, Glra3 -/- and Glra2/3 -/-) show that GlyRα2 inhibition enhances RF surround suppression and post-stimulus excitation in only WT OFF RGCs. Similarities in the responses in Glra2 -/- and Glra2/3 -/- RGCs verify these conclusions. Based on previous and current data, we propose that GlyRα2-mediated input uses a crossover inhibitory circuit. Further, we suggest that GlyRα2 modulates the OFF RGC RF center and surround independently. In summary, our results define a selective GlyR subunit-specific control of RF surround suppression in OFF RGCs. PMID:26923349

  12. Color opponent receptive fields self-organize in a biophysical model of visual cortex via spike-timing dependent plasticity

    PubMed Central

    Eguchi, Akihiro; Neymotin, Samuel A.; Stringer, Simon M.

    2014-01-01

    Although many computational models have been proposed to explain orientation maps in primary visual cortex (V1), it is not yet known how similar clusters of color-selective neurons in macaque V1/V2 are connected and develop. In this work, we address the problem of understanding the cortical processing of color information with a possible mechanism of the development of the patchy distribution of color selectivity via computational modeling. Each color input is decomposed into a red, green, and blue representation and transmitted to the visual cortex via a simulated optic nerve in a luminance channel and red–green and blue–yellow opponent color channels. Our model of the early visual system consists of multiple topographically-arranged layers of excitatory and inhibitory neurons, with sparse intra-layer connectivity and feed-forward connectivity between layers. Layers are arranged based on anatomy of early visual pathways, and include a retina, lateral geniculate nucleus, and layered neocortex. Each neuron in the V1 output layer makes synaptic connections to neighboring neurons and receives the three types of signals in the different channels from the corresponding photoreceptor position. Synaptic weights are randomized and learned using spike-timing-dependent plasticity (STDP). After training with natural images, the neurons display heightened sensitivity to specific colors. Information-theoretic analysis reveals mutual information between particular stimuli and responses, and that the information reaches a maximum with fewer neurons in the higher layers, indicating that estimations of the input colors can be done using the output of fewer cells in the later stages of cortical processing. In addition, cells with similar color receptive fields form clusters. Analysis of spiking activity reveals increased firing synchrony between neurons when particular color inputs are presented or removed (ON-cell/OFF-cell). PMID:24659956

  13. Caring Reflexivity

    ERIC Educational Resources Information Center

    Rallis, Sharon F.; Rossman, Gretchen B.

    2010-01-01

    This article provides a brief summary of the seven articles in this special issue through the lens of the concept of "caring reflexivity". In joining "caring" and "reflexivity", we deepen the conversation about what constitutes reflexivity, encouraging an explicit focus on the relational. Revisiting the first article, we argue that…

  14. Feasibility analysis of digital single lens reflex applied in the field of aerospace measurement

    NASA Astrophysics Data System (ADS)

    Feng, Xinghao; Li, Manliang; Tang, Xuehai

    2015-10-01

    The mainstrean digital single lens reflex (DSLR) image has the characteristics of true color and high quality, this paper proposes apply DSLR to probe spacecraft in order to obtain better quality Color images. Firstly, the performance parameters of mainstream DSLR and industrial-grade optical detector are analysed and compared detailedly; Secondly, the performance and positioning ways etc. of optical detector and DSLR system integrated special telephoto lens are analysed and compared. Furthermore, some experiments have been done in different conditions. The experiments indicate that the performances of DSLR and optical detector are similar. In addition, DSLR has the advantage of small size, low cost and Easy positioning, which can be used to obtain the scene of spacecraft in the takeoff phase and part of reentry phase.

  15. Optimizing your reception area.

    PubMed

    Lachter, Jesse; Raldow, Ann; Molin, Niki

    2012-01-01

    Through the optimization of reception areas (waiting rooms), physicians can improve the medical experiences of their patients. A qualitative investigation identified issues relevant to improving the quality of the reception area and was used to develop a thorough questionnaire. Most patients were satisfied with accessibility, reception area conditions, and performance of doctors and nurses. The main reasons for dissatisfaction were due to remediable points. No correlations were found between patient satisfaction and age, sex, or religion. A 36-item checklist for satisfaction with reception areas is offered as a useful tool for health quality self-assessment.

  16. Post eye-opening maturation of visual receptive field diameters in the superior colliculus of normal- and dark-reared rats.

    PubMed

    Binns, K E; Salt, T E

    1997-04-18

    When the rat's eyes open (P14) the retino-collicular projection is largely mature but the cortico-collicular afferents are naive and mature considerably in the following week. At P14, single units in the superior colliculus' superficial grey layer (SGS) had discrete receptive fields (RFs) (diameter = 15 +/- 1.6 degrees) which expanded with age, reaching 30 +/- 2.6 degrees at P21, possibly reflecting the increasing influence of the visual cortex, whose RFs are known to be enlarged at P21. Subsequently SGS RFs retracted to 13 +/- 1.3 degrees by P23. Dark-reared (DR) rats followed a similar but delayed developmental pattern, such that RFs were still large (27 +/- 3.4 degrees) at P24. By P30 however the RFs of DR rats were the same as those of normal adults. Thus visual experience accelerates the emergence of normal RFs in the SGS.

  17. Brain activations evoked by tactile stimulation varies with the intensity and not with number of receptive fields stimulated: An fMRI study

    NASA Astrophysics Data System (ADS)

    Ramirez Garzón, Y. T.; Pasaye, E. H.; Barrios, F. A.

    2014-11-01

    Using functional Magnetic Resonance Imaging (fMRI) it is possible to study the functional anatomy of primary cortices. Cortical representations in the primary somatosensory cortex have shown discrepancies between activations related to the same body region in some studies; these differences have been more pronounced for lower limb representations. The aim of this study was to observe the influence of the tactile stimulus intensity in somatosensory cortical responses using fMRI. Based in the sensitivity and pain threshold of each subject, we used Von Frey filaments for stimulate 12 control subject in three receptive fields on the right thigh. One filament near to sensitivity threshold (VFS), other close to pain threshold (VFP) and one intermediate filament between the two previous thresholds (VFI). The tactile stimulation with VFS produced no activation on SI, while that the contralateral SI was activated by stimulation with VFI in 5 subjects and with the stimulation of VFP in all subjects. Second level statistical analysis showed significant differences between SI activations related to the stimulation with VFP and VFI (VFP > VFI), in the comparison between the applied different intensities, a small cluster of activation was observed on SI for the unique possible contrast (VFP > VFI). The time course per trial for each subject was extracted and averaged to extract the activation in the contralateral SI and compared across the stimulus modalities, between the sites of field receptive stimulated and the intensities used. The time course of tactile stimulus responses revealed a consistent single peak of activity per cycle (30 s), approximately 12 s after the onset of the stimulus, with exception of the VFI stimulation,_which showed the peak at 10 s. Thus, our results indicate that the cortical representation of a tactile stimulus with fMRI is modulated for the intensity of the stimulus applied.

  18. Moro reflex

    MedlinePlus

    ... infants. Absence of the Moro reflex in an infant is abnormal. Absence on both sides suggests damage to the brain or spinal cord. Absence on only one side suggests either a broken shoulder bone or an injury to the group of nerves that run from ...

  19. The visual development of hand-centered receptive fields in a neural network model of the primate visual system trained with experimentally recorded human gaze changes.

    PubMed

    Galeazzi, Juan M; Navajas, Joaquín; Mender, Bedeho M W; Quian Quiroga, Rodrigo; Minini, Loredana; Stringer, Simon M

    2016-01-01

    Neurons have been found in the primate brain that respond to objects in specific locations in hand-centered coordinates. A key theoretical challenge is to explain how such hand-centered neuronal responses may develop through visual experience. In this paper we show how hand-centered visual receptive fields can develop using an artificial neural network model, VisNet, of the primate visual system when driven by gaze changes recorded from human test subjects as they completed a jigsaw. A camera mounted on the head captured images of the hand and jigsaw, while eye movements were recorded using an eye-tracking device. This combination of data allowed us to reconstruct the retinal images seen as humans undertook the jigsaw task. These retinal images were then fed into the neural network model during self-organization of its synaptic connectivity using a biologically plausible trace learning rule. A trace learning mechanism encourages neurons in the model to learn to respond to input images that tend to occur in close temporal proximity. In the data recorded from human subjects, we found that the participant's gaze often shifted through a sequence of locations around a fixed spatial configuration of the hand and one of the jigsaw pieces. In this case, trace learning should bind these retinal images together onto the same subset of output neurons. The simulation results consequently confirmed that some cells learned to respond selectively to the hand and a jigsaw piece in a fixed spatial configuration across different retinal views.

  20. Connectivity of Somatosensory Cortical Area 1 Forms an Anatomical Substrate for the Emergence of Multifinger Receptive Fields and Complex Feature Selectivity in the Squirrel Monkey (Saimiri sciureus)

    PubMed Central

    Ashaber, Mária; Pálfi, Emese; Friedman, Robert M; Palmer, Cory; Jákli, Balázs; Chen, Li Min; Kántor, Orsolya; Roe, Anna W; Négyessy, Laszló

    2014-01-01

    Converging evidence shows that interaction of digit-specific input, which is required to form global tactile percepts, begins as early as area 3b in the primary somatosensory cortex with the involvement of intrinsic lateral connections. How tactile processing is further elaborated in area 1, the next stage of the somatosensory cortical hierarchy, is less understood. This question was investigated by studying the tangential distribution of intrinsic and interareal connections of finger representations of area 1. Retrogradely labeled cell densities and anterogradely labeled fibers and terminal patches were plotted and quantified with respect to the hand representation by combining tract tracing with electrophysiological mapping and intrinsic signal optical imaging in somatosensory areas. Intrinsic connections of distal finger pad representations of area 1 spanned the representation of multiple digits indicating strong cross-digit connectivity. Area 1 distal finger pad regions also established high-density connections with homotopic regions of areas 3b and 2. Although similar to area 3b, connections of area 1 distributed more widely and covered a larger somatotopic representation including more proximal parts of the finger representations. The lateral connectivity pattern of area 1 is a suitable anatomical substrate of the emergence of multifinger receptive fields, complex feature selectivity, and invariant stimulus properties of the neurons. PMID:24214200

  1. The visual development of hand-centered receptive fields in a neural network model of the primate visual system trained with experimentally recorded human gaze changes.

    PubMed

    Galeazzi, Juan M; Navajas, Joaquín; Mender, Bedeho M W; Quian Quiroga, Rodrigo; Minini, Loredana; Stringer, Simon M

    2016-01-01

    Neurons have been found in the primate brain that respond to objects in specific locations in hand-centered coordinates. A key theoretical challenge is to explain how such hand-centered neuronal responses may develop through visual experience. In this paper we show how hand-centered visual receptive fields can develop using an artificial neural network model, VisNet, of the primate visual system when driven by gaze changes recorded from human test subjects as they completed a jigsaw. A camera mounted on the head captured images of the hand and jigsaw, while eye movements were recorded using an eye-tracking device. This combination of data allowed us to reconstruct the retinal images seen as humans undertook the jigsaw task. These retinal images were then fed into the neural network model during self-organization of its synaptic connectivity using a biologically plausible trace learning rule. A trace learning mechanism encourages neurons in the model to learn to respond to input images that tend to occur in close temporal proximity. In the data recorded from human subjects, we found that the participant's gaze often shifted through a sequence of locations around a fixed spatial configuration of the hand and one of the jigsaw pieces. In this case, trace learning should bind these retinal images together onto the same subset of output neurons. The simulation results consequently confirmed that some cells learned to respond selectively to the hand and a jigsaw piece in a fixed spatial configuration across different retinal views. PMID:27253452

  2. Weighted KPCA degree of homogeneity amended nonclassical receptive field inhibition model for salient contour extraction in low-light-level image.

    PubMed

    Zhang, Yi; Han, Jing; Yue, Jiang; Bai, Lian-Fa

    2014-06-01

    The stimulus response of the classical receptive field (CRF) of neuron in primary visual cortex is affected by its periphery [i.e., non-CRF (nCRF)]. This modulation exerts inhibition, which depends primarily on the correlation of both visual stimulations. The theory of periphery and center interaction with visual characteristics can be applied in night vision information processing. In this paper, a weighted kernel principal component analysis (WKPCA) degree of homogeneity (DH) amended inhibition model inspired by visual perceptual mechanisms is proposed to extract salient contour from complex natural scene in low-light-level image. The core idea is that multifeature analysis can recognize the homogeneity in modulation coverage effectively. Computationally, a novel WKPCA algorithm is presented to eliminate outliers and anomalous distribution in CRF and accomplish principal component analysis precisely. On this basis, a new concept and computational procedure for DH is defined to evaluate the dissimilarity between periphery and center comprehensively. Through amending the inhibition from nCRF to CRF by DH, our model can reduce the interference of noises, suppress details, and textures in homogeneous regions accurately. It helps to further avoid mutual suppression among inhomogeneous regions and contour elements. This paper provides an improved computational visual model with high-performance for contour detection from cluttered natural scene in night vision image. PMID:24760908

  3. A neural network model for the development of simple and complex cell receptive fields within cortical maps of orientation and ocular dominance.

    PubMed

    Olson, S J; Grossberg, S

    1998-03-01

    Prenatal development of the primary visual cortex leads to simple cells with spatially distinct and oriented ON and OFF subregions. These simple cells are organized into spatial maps of orientation and ocular dominance that exhibit singularities, fractures, and linear zones. On a finer spatial scale, simple cells occur that are sensitive to similar orientations but opposite contrast polarities, and exhibit both even-symmetric and odd-symmetric receptive fields. Pooling of outputs from oppositely polarized simple cells leads to complex cells that respond to both contrast polarities. A neural network model is described which simulates how simple and complex cells self-organize starting from unsegregated and unoriented geniculocortical inputs during prenatal development. Neighboring simple cells that are sensitive to opposite contrast polarities develop from a combination of spatially short-range inhibition and high-gain recurrent habituative excitation between cells that obey membrane equations. Habituation, or depression, of synapses controls reset of cell activations both through enhanced ON responses and OFF antagonistic rebounds. Orientation and ocular dominance maps form when high-gain medium-range recurrent excitation and long-range inhibition interact with the short-range mechanisms. The resulting structure clarifies how simple and complex cells contribute to perceptual processes such as texture segregation and perceptual grouping.

  4. Spatial dynamics of receptive fields in cat primary visual cortex related to the temporal structure of thalamocortical feedforward activity. Experiments and models.

    PubMed

    Suder, Katrin; Funke, Klaus; Zhao, Yongqiang; Kerscher, Nicolas; Wennekers, Thomas; Wörgötter, Florentin

    2002-06-01

    We investigated how changes in the temporal firing rate of thalamocortical activity affect the spatiotemporal structure of receptive field (RF) subunits in cat primary visual cortex. Spike activity of 67 neurons (48 simple, 19 complex cells) was extracellulary recorded from area 17/18 of anesthetized and paralyzed cats. A total of 107 subfields (on/off) were mapped by applying a reverse correlation technique to the activity elicited by bright and dark rectangles flashed for 300 ms in a 20x10 grid. We found that the width of the (suprathreshold) discharge fields shrank on average by 22% during this 300-ms-long stimulus presentation time. Fifty-eight subfields (54%) shrank by more than 20% of peak width and only ten (less than 10%) showed a slight increase over time. The main size reduction took place 40-60 ms after response onset, which corresponded to the transition from transient peak firing to tonic visual activity in thalamocortical relay cells (TC). The experimentally obtained RFs were then fitted with the aid of a neural field model of the primary visual pathway. Assuming a Gaussian-shaped spatial sensitivity profile across the RF subfield width, the model allowed us to estimate the subthreshold RF (depolarization field, D-field) from the minimal discharge field (MDF). The model allowed us to test to what degree the temporal dynamics of thalamocortical activity contributes to the spatiotemporal changes of cortical RFs. To this end, we performed the fitting procedure either with a pure feedforward model or with a field model that also included intracortical feedback. Spatial and temporal parameters obtained from fits of the experimental RFs matched closely to those achieved by simulating a pure feedforward system with the field model but were not compatible with additional intracortical feedback. Thus, our results show that dot stimulation, which optimally excites thalamocortical cells, leads to a shrinkage with respect to the size of the RF subfield at the

  5. Reflexives in Mohawk.

    ERIC Educational Resources Information Center

    Bonvillain, Nancy

    1994-01-01

    This paper presents an analysis of the meanings and uses of two reflexive morphemes in the Mohawk language. Reflexive "atat" is shown to have both reflexive and reciprocal meanings. It is also realized in kinship terms and in the transitive pronominal prefix "yutat." Semi-reflexive "at" has some reflexive functions, and can mark middle voice and…

  6. Facilitating Reflexivity in Preservice Science Teacher Education Using Video Analysis and Cogenerative Dialogue in Field-Based Methods Courses

    ERIC Educational Resources Information Center

    Siry, Christina; Martin, Sonya N.

    2014-01-01

    This paper presents an approach to preservice science teacher education coupling video analysis with dialogue as tools for fostering teachers' ability to notice and reflexively interpret events captured during teaching practicum with the intent of transforming classroom practice. In this approach, video becomes a tool with which teachers…

  7. [Oculorespiratory reflex].

    PubMed

    Thirion, B; Marchal, F; Pétry, L; George, J L; Crance, J P; Haberer, J P

    1990-01-01

    The lack of interest about oculorespiratory reflex (ORR) in surgery and experimental studies is obvious. However the authors insist on the importance of its clinical traduction. The purpose of this study is to determinate an experimental model with titration of stimulus (pressure or traction) and therapeutic test. Our first Results prove the clinic entity of O.R.R. In first conclusion, we can insist on the importance of ventilatory assistance during squint surgery and on the monitoring of PE CO2 and Sa O2.

  8. The visual development of hand-centered receptive fields in a neural network model of the primate visual system trained with experimentally recorded human gaze changes

    PubMed Central

    Galeazzi, Juan M.; Navajas, Joaquín; Mender, Bedeho M. W.; Quian Quiroga, Rodrigo; Minini, Loredana; Stringer, Simon M.

    2016-01-01

    ABSTRACT Neurons have been found in the primate brain that respond to objects in specific locations in hand-centered coordinates. A key theoretical challenge is to explain how such hand-centered neuronal responses may develop through visual experience. In this paper we show how hand-centered visual receptive fields can develop using an artificial neural network model, VisNet, of the primate visual system when driven by gaze changes recorded from human test subjects as they completed a jigsaw. A camera mounted on the head captured images of the hand and jigsaw, while eye movements were recorded using an eye-tracking device. This combination of data allowed us to reconstruct the retinal images seen as humans undertook the jigsaw task. These retinal images were then fed into the neural network model during self-organization of its synaptic connectivity using a biologically plausible trace learning rule. A trace learning mechanism encourages neurons in the model to learn to respond to input images that tend to occur in close temporal proximity. In the data recorded from human subjects, we found that the participant’s gaze often shifted through a sequence of locations around a fixed spatial configuration of the hand and one of the jigsaw pieces. In this case, trace learning should bind these retinal images together onto the same subset of output neurons. The simulation results consequently confirmed that some cells learned to respond selectively to the hand and a jigsaw piece in a fixed spatial configuration across different retinal views. PMID:27253452

  9. More Gamma More Predictions: Gamma-Synchronization as a Key Mechanism for Efficient Integration of Classical Receptive Field Inputs with Surround Predictions.

    PubMed

    Vinck, Martin; Bosman, Conrado A

    2016-01-01

    During visual stimulation, neurons in visual cortex often exhibit rhythmic and synchronous firing in the gamma-frequency (30-90 Hz) band. Whether this phenomenon plays a functional role during visual processing is not fully clear and remains heavily debated. In this article, we explore the function of gamma-synchronization in the context of predictive and efficient coding theories. These theories hold that sensory neurons utilize the statistical regularities in the natural world in order to improve the efficiency of the neural code, and to optimize the inference of the stimulus causes of the sensory data. In visual cortex, this relies on the integration of classical receptive field (CRF) data with predictions from the surround. Here we outline two main hypotheses about gamma-synchronization in visual cortex. First, we hypothesize that the precision of gamma-synchronization reflects the extent to which CRF data can be accurately predicted by the surround. Second, we hypothesize that different cortical columns synchronize to the extent that they accurately predict each other's CRF visual input. We argue that these two hypotheses can account for a large number of empirical observations made on the stimulus dependencies of gamma-synchronization. Furthermore, we show that they are consistent with the known laminar dependencies of gamma-synchronization and the spatial profile of intercolumnar gamma-synchronization, as well as the dependence of gamma-synchronization on experience and development. Based on our two main hypotheses, we outline two additional hypotheses. First, we hypothesize that the precision of gamma-synchronization shows, in general, a negative dependence on RF size. In support, we review evidence showing that gamma-synchronization decreases in strength along the visual hierarchy, and tends to be more prominent in species with small V1 RFs. Second, we hypothesize that gamma-synchronized network dynamics facilitate the emergence of spiking output that is

  10. Non-Centered Spike-Triggered Covariance Analysis Reveals Neurotrophin-3 as a Developmental Regulator of Receptive Field Properties of ON-OFF Retinal Ganglion Cells

    PubMed Central

    Cantrell, Donald R.; Cang, Jianhua; Troy, John B.; Liu, Xiaorong

    2010-01-01

    The functional separation of ON and OFF pathways, one of the fundamental features of the visual system, starts in the retina. During postnatal development, some retinal ganglion cells (RGCs) whose dendrites arborize in both ON and OFF sublaminae of the inner plexiform layer transform into RGCs with dendrites that monostratify in either the ON or OFF sublamina, acquiring final dendritic morphology in a subtype-dependent manner. Little is known about how the receptive field (RF) properties of ON, OFF, and ON-OFF RGCs mature during this time because of the lack of a reliable and efficient method to classify RGCs into these subtypes. To address this deficiency, we developed an innovative variant of Spike Triggered Covariance (STC) analysis, which we term Spike Triggered Covariance – Non-Centered (STC-NC) analysis. Using a multi-electrode array (MEA), we recorded the responses of a large population of mouse RGCs to a Gaussian white noise stimulus. As expected, the Spike-Triggered Average (STA) fails to identify responses driven by symmetric static nonlinearities such as those that underlie ON-OFF center RGC behavior. The STC-NC technique, in contrast, provides an efficient means to identify ON-OFF responses and quantify their RF center sizes accurately. Using this new tool, we find that RGCs gradually develop sensitivity to focal stimulation after eye opening, that the percentage of ON-OFF center cells decreases with age, and that RF centers of ON and ON-OFF cells become smaller. Importantly, we demonstrate for the first time that neurotrophin-3 (NT-3) regulates the development of physiological properties of ON-OFF center RGCs. Overexpression of NT-3 leads to the precocious maturation of RGC responsiveness and accelerates the developmental decrease of RF center size in ON-OFF cells. In summary, our study introduces STC-NC analysis which successfully identifies subtype RGCs and demonstrates how RF development relates to a neurotrophic driver in the retina. PMID

  11. More Gamma More Predictions: Gamma-Synchronization as a Key Mechanism for Efficient Integration of Classical Receptive Field Inputs with Surround Predictions

    PubMed Central

    Vinck, Martin; Bosman, Conrado A.

    2016-01-01

    During visual stimulation, neurons in visual cortex often exhibit rhythmic and synchronous firing in the gamma-frequency (30–90 Hz) band. Whether this phenomenon plays a functional role during visual processing is not fully clear and remains heavily debated. In this article, we explore the function of gamma-synchronization in the context of predictive and efficient coding theories. These theories hold that sensory neurons utilize the statistical regularities in the natural world in order to improve the efficiency of the neural code, and to optimize the inference of the stimulus causes of the sensory data. In visual cortex, this relies on the integration of classical receptive field (CRF) data with predictions from the surround. Here we outline two main hypotheses about gamma-synchronization in visual cortex. First, we hypothesize that the precision of gamma-synchronization reflects the extent to which CRF data can be accurately predicted by the surround. Second, we hypothesize that different cortical columns synchronize to the extent that they accurately predict each other’s CRF visual input. We argue that these two hypotheses can account for a large number of empirical observations made on the stimulus dependencies of gamma-synchronization. Furthermore, we show that they are consistent with the known laminar dependencies of gamma-synchronization and the spatial profile of intercolumnar gamma-synchronization, as well as the dependence of gamma-synchronization on experience and development. Based on our two main hypotheses, we outline two additional hypotheses. First, we hypothesize that the precision of gamma-synchronization shows, in general, a negative dependence on RF size. In support, we review evidence showing that gamma-synchronization decreases in strength along the visual hierarchy, and tends to be more prominent in species with small V1 RFs. Second, we hypothesize that gamma-synchronized network dynamics facilitate the emergence of spiking output that

  12. Diversity Networking Reception

    NASA Astrophysics Data System (ADS)

    2014-03-01

    Join us at the APS Diversity Reception to relax, network with colleagues, and learn about programs and initiatives for women, underrepresented minorities, and LGBT physicists. You'll have a great time meeting friends in a supportive environment and making connections.

  13. Reception problems and options

    NASA Astrophysics Data System (ADS)

    Hastings, J. F. C.

    1982-04-01

    The apparatus needed for home satellite reception is described. A distinction is made between 'normal' signals - those intended for reception in a particular country - and 'spillover' transmissions, that is, transmissions intended for reception elsewhere but susceptible of reception with the appropriate equipment. For normal signals, a parabolic antenna of 0.7-0.9 m is required; for spillover transmissions, a steerable dish would be needed, together with tuning over the whole 800 MHz band. A figure showing the relationship between antenna size, receiver noise figure, and signal strength is included. It is thought that practical and economic receivers will have a noise figure between 3 and 6 dB. With regard to the placement of the dish, it is pointed out that there must be a line of sight from the dish to the satellite. A proposed system for a practical satellite TV receiver is described. A double superhet is employed, with the first frequency changer mounted directly on the antenna. The first local oscillator is fixed, so that each transmission frequency corresponds to a particular first IF. For a half-band receiver, the first IF covers the 400 MHz between 950 MHz and 1.35 GHz.

  14. Supersonic Leading Edge Receptivity

    NASA Technical Reports Server (NTRS)

    Maslov, Anatoly A.

    1998-01-01

    This paper describes experimental studies of leading edge boundary layer receptivity for imposed stream disturbances. Studies were conducted in the supersonic T-325 facility at ITAM and include data for both sharp and blunt leading edges. The data are in agreement with existing theory and should provide guidance for the development of more complete theories and numerical computations of this phenomena.

  15. Wireless quantified reflex device

    NASA Astrophysics Data System (ADS)

    Lemoyne, Robert Charles

    The deep tendon reflex is a fundamental aspect of a neurological examination. The two major parameters of the tendon reflex are response and latency, which are presently evaluated qualitatively during a neurological examination. The reflex loop is capable of providing insight for the status and therapy response of both upper and lower motor neuron syndromes. Attempts have been made to ascertain reflex response and latency, however these systems are relatively complex, resource intensive, with issues of consistent and reliable accuracy. The solution presented is a wireless quantified reflex device using tandem three dimensional wireless accelerometers to obtain response based on acceleration waveform amplitude and latency derived from temporal acceleration waveform disparity. Three specific aims have been established for the proposed wireless quantified reflex device: 1. Demonstrate the wireless quantified reflex device is reliably capable of ascertaining quantified reflex response and latency using a quantified input. 2. Evaluate the precision of the device using an artificial reflex system. 3.Conduct a longitudinal study respective of subjects with healthy patellar tendon reflexes, using the wireless quantified reflex evaluation device to obtain quantified reflex response and latency. Aim 1 has led to the steady evolution of the wireless quantified reflex device from a singular two dimensional wireless accelerometer capable of measuring reflex response to a tandem three dimensional wireless accelerometer capable of reliably measuring reflex response and latency. The hypothesis for aim 1 is that a reflex quantification device can be established for reliably measuring reflex response and latency for the patellar tendon reflex, comprised of an integrated system of wireless three dimensional MEMS accelerometers. Aim 2 further emphasized the reliability of the wireless quantified reflex device by evaluating an artificial reflex system. The hypothesis for aim 2 is that

  16. Reflexives in Veracruz Huastec.

    ERIC Educational Resources Information Center

    Constable, Peter G.

    A study examines various Huastec clause types that are reflexive in some sense, including ordinary reflexives, which involve co-reference. Two mutually exclusive morphosyntactic devices are used in Huastec: reflexive pronouns and verbal morphology. In this way, Huastec is like various European languages. Clauses involving reflexive pronouns and…

  17. Education & Diversity Reception

    NASA Astrophysics Data System (ADS)

    2016-03-01

    Join us to relax, unwind, and recognize new fellows and award winners at the Education & Diversity Reception sponsored by the Forum on Education, the Committee on Minorities, and the Committee on the Status of Women in Physics. We will recognize new Forum on Education Fellows, recipients of the Committee on Education's Award for Improving Undergraduate Physics Education, as well as women and minority physicists who have received APS prizes, awards, and fellowships. Light refreshments will be served. All are welcome; no registration required.

  18. Portraying Reflexivity in Health Services Research.

    PubMed

    Rae, John; Green, Bill

    2016-09-01

    A model is proposed for supporting reflexivity in qualitative health research, informed by arguments from Bourdieu and Finlay. Bourdieu refers to mastering the subjective relation to the object at three levels-the overall social space, the field of specialists, and the scholastic universe. The model overlays Bourdieu's levels of objectivation with Finlay's three stages of research (pre-research, data collection, and data analysis). The intersections of these two ways of considering reflexivity, displayed as cells of a matrix, pose questions and offer prompts to productively challenge health researchers' reflexivity. Portraiture is used to show how these challenges and prompts can facilitate such reflexivity, as illustrated in a research project.

  19. Portraying Reflexivity in Health Services Research.

    PubMed

    Rae, John; Green, Bill

    2016-09-01

    A model is proposed for supporting reflexivity in qualitative health research, informed by arguments from Bourdieu and Finlay. Bourdieu refers to mastering the subjective relation to the object at three levels-the overall social space, the field of specialists, and the scholastic universe. The model overlays Bourdieu's levels of objectivation with Finlay's three stages of research (pre-research, data collection, and data analysis). The intersections of these two ways of considering reflexivity, displayed as cells of a matrix, pose questions and offer prompts to productively challenge health researchers' reflexivity. Portraiture is used to show how these challenges and prompts can facilitate such reflexivity, as illustrated in a research project. PMID:26935721

  20. Interior view of Gold Star Mothers' reception room from northwest. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view of Gold Star Mothers' reception room from northwest. Note c. 1935 furniture and fireplace with early electric grate. - Flanders Field American Cemetery & Memorial, Superintendent's Quarters, Wortegemseweg 117, Waregem, West Flanders (Belgium)

  1. Embodied Self-Reflexivity

    ERIC Educational Resources Information Center

    Pagis, Michal

    2009-01-01

    Drawing on G. H. Mead and Merleau-Ponty, this paper aims to extend our understanding of self-reflexivity beyond the notion of a discursive, abstract, and symbolic process. It offers a framework for embodied self-reflexivity, which anchors the self in the reflexive capacity of bodily sensations. The data consist of two years of ethnographic…

  2. The Dynamics of the Stapedial Acoustic Reflex.

    NASA Astrophysics Data System (ADS)

    Moss, Sherrin Mary

    , and their effect upon the contralateral reflex arc from the site of the superior olivary complex to the motoneurones innervating the stapedius, account for the difference between the contralateral and ipsilateral reflex thresholds and dynamic characteristics. In the past two years the measurement technique used for the experimental work has developed from an audiological to a neurological diagnostic tool. This has enabled the results from the study to be applied in the field for valuable biomechanical and neurological explanations of the reflex response. (Abstract shortened by UMI.).

  3. From endometrial receptivity to infertility.

    PubMed

    Tabibzadeh, S; Shea, W; Lessey, B A; Broome, J

    1999-01-01

    Implantation of the blastocyst in endometrium requires establishment of a coordinated molecular dialogue between the embryo and the endometrium. Factors instrumental in the preparation of a receptive endometrium are derived from the hypothalamic-pituitary-gonadal axis. These factors modulate the expression of genes that drive the endometrium throughout the characteristic menstrual cycles. During each menstrual cycle, a series of coordinated, architectural, morphological, cytochemical, and molecular changes ultimately lead to the preparation of a receptive endometrium during the putative "receptive period" or "implantation window." It is during this critical period that a proper dialogue can be established between an intrusive blastocyst and a receptive endometrium. If, for any reason, this dialogue is not established or is perturbed, the embryo is aborted. The natural fate of the receptive endometrium, in the absence of implantation, is development of a second set of changes that ultimately lead to menstruation. The identity of the molecular repertoire that makes endometrium receptive to implantation and/or lead to menstruation is being revealed and broadly includes cytokines, heat shock factors, adhesion molecules and matrix metalloproteases. We identified a novel gene of the transforming growth factor-beta, superfamily of molecules, the so-called endometrial bleeding--associated factor or ebaf, whose expression is confined to the late secretory and menstrual phases. Various forms of female infertility were associated with dysregulated expression of ebaf during the implantation window. The findings show an occult molecular defect of endometrial receptivity that seems to be due to dysregulated and premature expression of a member of the premenstrual molecular repertoire. The dysregulated expression of ebaf may assist in the identification, prognostication, and monitoring of treatment of infertile women.

  4. Accelerating Reflexivity? An Ethno-Theater Interpretation of a Pre-Service Teacher Literacy Methods Field Experience

    ERIC Educational Resources Information Center

    Schneider, Jenifer Jasinski; King, James R.; Kozdras, Deborah; Minick, Vanessa; Welsh, James L.

    2012-01-01

    During a teaching methods field experience, we initiated several processes to facilitate pre-service teachers' reflection, empowerment, and performance as they learned to teach students. Through an ethno-theater presentation and subsequent revisions to an ethno-theater script, we turned the reflective lens on ourselves as we discovered instances…

  5. Boundary layer receptivity and control

    NASA Technical Reports Server (NTRS)

    Hill, D. C.

    1993-01-01

    Receptivity processes initiate natural instabilities in a boundary layer. The instabilities grow and eventually break down to turbulence. Consequently, receptivity questions are a critical element of the analysis of the transition process. Success in modeling the physics of receptivity processes thus has a direct bearing on technological issues of drag reduction. The means by which transitional flows can be controlled is also a major concern: questions of control are tied inevitably to those of receptivity. Adjoint systems provide a highly effective mathematical method for approaching many of the questions associated with both receptivity and control. The long term objective is to develop adjoint methods to handle increasingly complex receptivity questions, and to find systematic procedures for deducing effective control strategies. The most elementary receptivity problem is that in which a parallel boundary layer is forced by time-harmonic sources of various types. The characteristics of the response to such forcing form the building blocks for more complex receptivity mechanisms. The first objective of this year's research effort was to investigate how a parallel Blasius boundary layer responds to general direct forcing. Acoustic disturbances in the freestream can be scattered by flow non-uniformities to produce Tollmien-Schlichting waves. For example, scattering by surface roughness is known to provide an efficient receptivity path. The present effort is directed towards finding a solution by a simple adjoint analysis, because adjoint methods can be extended to more complex problems. In practice, flows are non-parallel and often three-dimensional. Compressibility may also be significant in some cases. Recent developments in the use of Parabolized Stability Equations (PSE) offer a promising possibility. By formulating and solving a set of adjoint parabolized equations, a method for mapping the efficiency with which external forcing excites the three

  6. What is a reflex?

    PubMed Central

    Truog, Robert D.

    2015-01-01

    Uncertainty in diagnosing disorders of consciousness, and specifically in determining whether consciousness has been lost or retained, poses challenging scientific and ethical questions. Recent neuroimaging-based tests for consciousness have cast doubt on the reliability of behavioral criteria in assessing states of consciousness and generate new questions about the assumptions used in formulating coherent diagnostic criteria. The reflex, a foundational diagnostic tool, offers unique insight into these disorders; behaviors produced by unconscious patients are thought to be purely reflexive, whereas those produced by conscious patients can be volitional. Further investigation, however, reveals that reflexes cannot be reliably distinguished from conscious behaviors on the basis of any generalizable empirical characteristics. Ambiguity between reflexive and conscious behaviors undermines the capacity of the reflex to distinguish between disorders of consciousness and has implications for how these disorders should be conceptualized in future diagnostic criteria. PMID:26085602

  7. Bourdieu and Science Studies: Toward a Reflexive Sociology

    ERIC Educational Resources Information Center

    Hess, David J.

    2011-01-01

    Two of Bourdieu's fundamental contributions to science studies--the reflexive analysis of the social and human sciences and the concept of an intellectual field--are used to frame a reflexive study of the history and social studies of science and technology as an intellectual field in the United States. The universe of large, Ph.D.-granting…

  8. On Reflexive Data Models

    SciTech Connect

    Petrov, S.

    2000-08-20

    An information system is reflexive if it stores a description of its current structure in the body of stored information and is acting on the base of this information. A data model is reflexive, if its language is meta-closed and can be used to build such a system. The need for reflexive data models in new areas of information technology applications is argued. An attempt to express basic notions related to information systems is made in the case when the system supports and uses meta-closed representation of the data.

  9. The Receptive Side of Teaching

    ERIC Educational Resources Information Center

    Hruska, Barbara

    2008-01-01

    When observing teachers in action, one is likely to witness explaining, modeling, managing, guiding, and encouraging. These expressive behaviors constitute a directive force moving outward from teacher to students. Though less visible to an outside observer, teaching also requires receptive skills, the ability to take in information by being fully…

  10. Endometrial receptivity array: Clinical application.

    PubMed

    Mahajan, Nalini

    2015-01-01

    Human implantation is a complex process requiring synchrony between a healthy embryo and a functionally competent or receptive endometrium. Diagnosis of endometrial receptivity (ER) has posed a challenge and so far most available tests have been subjective and lack accuracy and a predictive value. Microarray technology has allowed identification of the transcriptomic signature of the window of receptivity window of implantation (WOI). This technology has led to the development of a molecular diagnostic tool, the ER array (ERA) for diagnosis of ER. Use of this test in patients with recurrent implantation failure (RIF) has shown that the WOI is displaced in a quarter of these patients and use of a personalized embryo transfer (pET) on the day designated by ERA improves reproductive performance. Our results in the Indian population revealed an endometrial factor in 27.5% RIF patients, which was significantly greater than the non-RIF group 15% (P = 0.04). After pET, the overall ongoing pregnancy rate was 42.4% and implantation rate was 33%, which was at par with our in-vitro fertilization results over 1-year. We also performed ERA in patients with persistently thin endometrium, and it was reassuring to find that the endometrium in 75% of these patients was receptive despite being 6 mm or less. A pregnancy rate of 66.7% was achieved in this group. Though larger studies are required to validate these results ERA has become a useful tool in our diagnostic armamentarium for ER. PMID:26538853

  11. The Grasp Reflex and Moro Reflex in Infants: Hierarchy of Primitive Reflex Responses

    PubMed Central

    Futagi, Yasuyuki; Toribe, Yasuhisa; Suzuki, Yasuhiro

    2012-01-01

    The plantar grasp reflex is of great clinical significance, especially in terms of the detection of spasticity. The palmar grasp reflex also has diagnostic significance. This grasp reflex of the hands and feet is mediated by a spinal reflex mechanism, which appears to be under the regulatory control of nonprimary motor areas through the spinal interneurons. This reflex in human infants can be regarded as a rudiment of phylogenetic function. The absence of the Moro reflex during the neonatal period and early infancy is highly diagnostic, indicating a variety of compromised conditions. The center of the reflex is probably in the lower region of the pons to the medulla. The phylogenetic meaning of the reflex remains unclear. However, the hierarchical interrelation among these primitive reflexes seems to be essential for the arboreal life of monkey newborns, and the possible role of the Moro reflex in these newborns was discussed in relation to the interrelationship. PMID:22778756

  12. Human psychophysical analysis of receptive field-like properties. I. A new transient-like visual response using a moving windmill (Werblin-type) target.

    PubMed

    Enoch, J M; Lazarus, J; Johnson, C A

    1976-06-01

    A human transient-like visual response has been revealed psychophysically with a rotating windmill target, similar to that used by Werblin in his recent studies of the retina of Necturus. The windmill pattern evoked complex perceptual phenomena (important in and of themselves) which were minimized by using a high luminance for the "criterion" flashing test field (relative to its increment threshold), and by moving the four-vaned windmill pattern at a rate of two complete revolutions per second. The transient response, herein defined as the difference in threshold between the stationary and moving windmill conditions, was greatest when the windmill vanes fell completely within the sensitization (inhibition-like) portion of the Westheimer function determined at the same retinal locus. The test has been developed so that it may be readily adapted to available clinical equipment for future diagnostic purposes .

  13. Transition receptivity and control: Computations

    NASA Astrophysics Data System (ADS)

    Reed, Helen L.; Saric, William S.

    1994-03-01

    We modeled the receptivity of the laminar boundary layer on a semi-infinite flat plate with a modified super-elliptic leading edge using a spatial direct numerical simulation. The incompressible flow was simulated by solving the governing full Navier-Stokes equations in general curvilinear coordinates by a finite-difference method. First, the steady basic-state solution was obtained in a transient approach using spatially varying time steps. Then, time-harmonic oscillations of the freestream streamwise velocity, modeling sound or spanwise vorticity, were applied as unsteady boundary conditions, and the governing equations were solved to evaluate the spatial and temporal developments of the perturbation leading to instability waves in the boundary layer. The effects of leading-edge radius and geometry on receptivity were determined. The work was closely coordinated with the experimental program. The computational work was also extended to solve the parabolized Navier-Stokes equations for the evolution of Gortler vortices in the presence of concave and convex curvature. Experiments were conducted on the receptivity of T-S waves to freestream sound in four different cases: (1) two-dimensional roughness elements; (2) the interaction and control of T-S waves with 2-D roughness; (3) three-dimensional roughness clements; and (4) the leading edge. T-S wave amplitudes were measured as a function of freestream sound level and the roughness height for both 2-D and 3-D roughness elements.

  14. Measuring bilingual children's receptive vocabularies.

    PubMed

    Umbel, V M; Pearson, B Z; Fernández, M C; Oller, D K

    1992-08-01

    Receptive vocabulary of Hispanic children in Miami was tested in both English and Spanish with complementary standardized tests, the Peabody Picture Vocabulary Test (PPVT-R) and the Test de Vocabulario en Imágenes Peabody (TVIP-H). 105 bilingual first graders, of middle to high socioeconomic status relative to national norms, were divided according to the language(s) spoken in their homes. Both groups, whether they spoke only Spanish in the home (OSH) or both English and Spanish in the home (ESH), performed near the mean of 100 in Spanish receptive vocabulary (TVIP-H means 97.0 and 96.5); in contrast, ESH group children scored more than 1 SD higher in English than OSH group children (PPVT-R means 88.0 and 69.7, respectively). It appears, therefore, that learning 2 languages at once does not harm receptive language development in the language of origin, while it does lay the groundwork for superior performance in the majority language. Furthermore, an analysis of translation equivalents, items shared by both tests, shows that a statistically significant portion of bilingual children's lexical knowledge does not overlap in their 2 languages and is therefore not reflected in single-language scores.

  15. Noxious stimuli do not determine reflex cardiorespiratory effects in anesthetized rabbits.

    PubMed

    Raimondi, G; Legramante, J M; Iellamo, F; Frisardi, G; Cassarino, S; Peruzzi, G

    1996-12-01

    The main purpose of this study is to examine whether the stimulation of an exclusively pain-sensing receptive field (dental pulp) could determine cardiorespiratory effects in animals in which the cortical integration of the peripheral information is abolished by deep anesthesia. In 15 anesthetized (alpha-chloralose and urethan) rabbits, low (3-Hz)- and high-frequency (100-Hz) electrical dental pulp stimulation was performed. Because this stimulation caused dynamic and static reflex contractions of the digastric muscles leading to jaw opening jaw-opening reflex (JOR); an indirect sign of algoceptive fiber activation], experimentally induced direct dynamic and static contractions of the digastric muscle were also performed. The low- and high-frequency stimulation of the dental pulp determined cardiovascular [systolic arterial pressure (SAP): -21.7 +/- 4.6 and 10.8 +/- 4.7 mmHg, respectively] and respiratory [pulmonary ventilation (VE): 145.1 +/- 44.9 and 109.3 +/- 28.4 ml/min, respectively] reflex responses similar to those observed during experimentally induced dynamic (SAP: -17.5 +/- 4.2 mmHg; VE: 228.0 +/- 58.5 ml/min) and static (SAP: 5.8 +/- 1.5 mmHg; VE: 148.0 +/- 75.3 ml/min) muscular contractions. The elimination of digastric muscular contraction (JOR) obtained by muscular paralysis did away with the cardiovascular changes induced by dental pulp stimulation, the effectiveness of which in stimulating dental pulp receptors has been shown by recording trigeminal-evoked potentials in six additional rabbits. The main conclusion was that, in deeply anesthetized animals, an algesic stimulus is unable to determine cardiorespiratory effects, which appear to be exclusively linked to the stimulation of ergoreceptors induced by muscular contraction.

  16. Corneomandibular reflex: Anatomical basis

    PubMed Central

    Pistacchi, Michele; Gioulis, Manuela; Mazzon, Davide; Marsala, Sandro Zambito

    2015-01-01

    Corneomandibular reflex is a pathological phenomenon evident in cases of severe brainstem damage. It is considered to be a pathological exteroceptive reflex, associated with precentro bulbar tract lesions. The sign is useful in distinguishing central neurological injuries to metabolic disorders in acutely comatose patients, localizing lesions to the upper brainstem area, determining the depth of coma and its evolution, providing evidence of uncal or transtentorial herniation in acute cerebral hemisphere lesions, and it is a marker of supraspinal level impairment in amyotrophic lateral sclerosis and multiple sclerosis. This sign was evident in a patient with severe brain damage. We discuss the literature findings and its relevance in prognosis establishment. PMID:26752910

  17. Experimenting With Baroreceptor Reflexes

    NASA Technical Reports Server (NTRS)

    Eckberg, Dwain L.; Goble, Ross L.

    1988-01-01

    Carotid arteries stimulated by pressure or suction on neck. Baro-Cuff is silicone-rubber chamber that fits on front of subject's neck. Electronic system, stepping motor, bellows, and umbilical tube furnish controlled pressure to chamber. Pressure sensor provides feedback to microprocessor in electronic system. Developed to study blood-pressure-reflex responses of astronauts in outer space. Useful for terrestrial studies of patients with congestive heart failure, chronic diabetes mellitus, and other conditions in which blood-pressure-reflex controls behave abnormally.

  18. Reflex control of immunity

    PubMed Central

    Tracey, Kevin J.

    2015-01-01

    Inflammation can cause damage and even death. What controls this primitive and potentially lethal innate immune response to injury and infection? Molecular and neurophysiological studies during the past decade have revealed a pivotal answer: immunity is coordinated by neural circuits that operate reflexively The afferent arc of the reflex consists of nerves that sense injury and infection. This activates efferent neural circuits, including the cholinergic anti-inflammatory pathway that modulate immune responses and the progression of inflammatory diseases. It might be possible to develop therapeutics that target neural networks for the treatment of inflammatory disorders. PMID:19461672

  19. Reflexivity in Pigeons

    ERIC Educational Resources Information Center

    Sweeney, Mary M.; Urcuioli, Peter J.

    2010-01-01

    A recent theory of pigeons' equivalence-class formation (Urcuioli, 2008) predicts that reflexivity, an untrained ability to match a stimulus to itself, should be observed after training on two "mirror-image" symbolic successive matching tasks plus identity successive matching using some of the symbolic matching stimuli. One group of pigeons was…

  20. Primitive reflexes in Parkinson's disease.

    PubMed Central

    Vreeling, F W; Verhey, F R; Houx, P J; Jolles, J

    1993-01-01

    A standardised protocol for the examination of 15 primitive reflexes in which the amplitude and the persistence were scored separately, was applied to 25 patients with Parkinson's disease and an equal number of healthy matched control subjects. Most reflexes were found considerably more often in the patients than in the control subjects, especially the snout, the glabellar tap, and its variant, the nasopalpebral reflex. Only the mouth open finger spread reflex was present more often in the control subjects. For all reflexes except this last, the scores for amplitude and persistence of the reflexes for the control group never exceeded the scores for the patient group. Reflexes persisted more often in the patients than in the control subjects. Parkinsonism alone can explain a large number of primitive reflexes, irrespective of the severity or duration of the disease. In contrast, the number of reflexes was related more closely to cognitive scales. It is concluded that such reflexes may be helpful in diagnosing Parkinson's disease. In addition, a standardised protocol for eliciting and scoring is essential for the study of these reflexes in parkinsonism and other neuropsychiatric conditions. PMID:8270937

  1. Spinal reflexes in brain death.

    PubMed

    Beckmann, Yesim; Çiftçi, Yeliz; Incesu, Tülay Kurt; Seçil, Yaprak; Akhan, Galip

    2014-12-01

    Spontaneous and reflex movements have been described in brain death and these unusual movements might cause uncertainties in diagnosis. In this study we evaluated the presence of spinal reflexes in patients who fulfilled the criteria for brain death. Thirty-two (22 %) of 144 patients presented unexpected motor movements spontaneously or during examinations. These patients exhibited the following signs: undulating toe, increased deep tendon reflexes, plantar responses, Lazarus sign, flexion-withdrawal reflex, facial myokymia, neck-arm flexion, finger jerks and fasciculations. In comparison, there were no significant differences in age, sex, etiology of brain death and hemodynamic laboratory findings in patients with and without reflex motor movement. Spinal reflexes should be well recognized by physicians and it should be born in mind that brain death can be determined in the presence of spinal reflexes.

  2. Reflexivity in pigeons.

    PubMed

    Sweeney, Mary M; Urcuioli, Peter J

    2010-11-01

    A recent theory of pigeons' equivalence-class formation (Urcuioli, 2008) predicts that reflexivity, an untrained ability to match a stimulus to itself, should be observed after training on two "mirror-image" symbolic successive matching tasks plus identity successive matching using some of the symbolic matching stimuli. One group of pigeons was trained in this fashion; a second group was trained similarly but with successive oddity (rather than identity). Subsequently, comparison-response rates on novel matching versus mismatching sequences with the remaining symbolic matching stimuli were measured on nonreinforced probe trials. Higher rates were observed on matching than on mismatching probes in the former group. The opposite effect--higher rates on mismatching than matching probes--was mostly absent in the latter group, despite being predicted by the theory. Nevertheless, the ostensible reflexivity effect observed in former group may be the first time this phenomenon has been demonstrated in any animal.

  3. A Receptive Perspective for Introductory German.

    ERIC Educational Resources Information Center

    Lovik, Thomas A.

    1995-01-01

    Suggests that additional attention to the sequencing of the grammatical structures needed for receptive comprehension might alleviate the problems associated with first-year German textbooks. The simple past tense, word order, and the indefinite pronoun "man" are used to illustrate the concept of a receptive grammar. (14 references) (Author/CK)

  4. [Human physiology: images and practices of the reflex].

    PubMed

    Wübben, Yvonne

    2010-01-01

    The essay examines the function of visualizations and practices in the formation of the reflex concept from Thomas Willis to Marshall Hall. It focuses on the specific form of reflex knowledge that images and practices can contain. In addition, the essay argues that it is through visual representations and experimental practices that technical knowledge is transferred to the field of human reflex physiology. When using technical metaphors in human physiology authors often seem to feel obliged to draw distinctions between humans, machines and animals. On closer scrutiny, these distinctions sometimes fail to establish firm borders between the human and the technical.

  5. [Principle of least action, physiology of vision, and conditioned reflexes theory].

    PubMed

    Shelepin, Iu E; Krasil'nikov, N N

    2003-06-01

    The variation principles such as principle of least action by Maupertuis (1740) and Fermat principle (1660) are fundamental for physics. They permit to establish a property by which the actual state is differing from all possible states of the system. The variation approach permits to establish equation of motion and equilibrium of a material system on the basis of one common rule which reduces to the search of the function extremes, describes this property of the system. So for the optical systems, crucial is the time and not the length of the way. According to Fermat principles, the light "choosen" from all possible ways connects two dots in the way which needs the least time. Generality of the variation principles guarantees success of their use in brain function investigations. Between different attempts to apply the variation principles to psychology and linguistics, the Zipf principle of least effort must be distinguished. Zipf (1949) demonstrated that languages and some artificial codes satisfied the least principle. For the brain physiology, classical conditioned reflex theory is the ideal area of variation principles application. According to this approach, conditioning leads to finding the extreme during fixation of the temporal link. In vision, physiological investigations are difficult because the signal has many dimensions. For example, during perception of spatial properties of surrounding world, in vision is realized minimization (reduction) of spatial-frequency spectrum of the scene. The receptive fields provide optimal accumulation of the signal. In ontogenesis, signal--noise ratio becomes optimal as receptive fields minimized the internal noise spectrum. According to the theory of match filtration, in the visual system recognition is carryied out by minimal differences between the image description in the visual system and storage in the human memory template of that image. The variation principles help to discover the physical property of

  6. [Principle of least action, physiology of vision, and conditioned reflexes theory].

    PubMed

    Shelepin, Iu E; Krasil'nikov, N N

    2003-06-01

    The variation principles such as principle of least action by Maupertuis (1740) and Fermat principle (1660) are fundamental for physics. They permit to establish a property by which the actual state is differing from all possible states of the system. The variation approach permits to establish equation of motion and equilibrium of a material system on the basis of one common rule which reduces to the search of the function extremes, describes this property of the system. So for the optical systems, crucial is the time and not the length of the way. According to Fermat principles, the light "choosen" from all possible ways connects two dots in the way which needs the least time. Generality of the variation principles guarantees success of their use in brain function investigations. Between different attempts to apply the variation principles to psychology and linguistics, the Zipf principle of least effort must be distinguished. Zipf (1949) demonstrated that languages and some artificial codes satisfied the least principle. For the brain physiology, classical conditioned reflex theory is the ideal area of variation principles application. According to this approach, conditioning leads to finding the extreme during fixation of the temporal link. In vision, physiological investigations are difficult because the signal has many dimensions. For example, during perception of spatial properties of surrounding world, in vision is realized minimization (reduction) of spatial-frequency spectrum of the scene. The receptive fields provide optimal accumulation of the signal. In ontogenesis, signal--noise ratio becomes optimal as receptive fields minimized the internal noise spectrum. According to the theory of match filtration, in the visual system recognition is carryied out by minimal differences between the image description in the visual system and storage in the human memory template of that image. The variation principles help to discover the physical property of

  7. Blends of rostral and caudal scratch reflex motor patterns elicited by simultaneous stimulation of two sites in the spinal turtle.

    PubMed

    Stein, P S; Camp, A W; Robertson, G A; Mortin, L I

    1986-08-01

    Simultaneous tactile stimulation of 2 sites on the body surface of a spinal turtle elicits complex blends of the scratch forms and motor patterns associated with each site. Our previous work has utilized 1-site stimulation to elicit distinct forms of the scratch reflex in the spinal turtle (Mortin et al., 1985; Robertson et al., 1985). Using this paradigm, stimulation of a site on the shell bridge anterior to the hindlimb elicits a rostral scratch reflex in which the dorsum of the foot rubs against the stimulated site; stimulation of a site near the tail elicits a caudal scratch reflex in which the heel or side of the foot rubs against the stimulated site (Mortin et al., 1985). During each scratch cycle, the monoarticular knee extensor muscle is active when the limb rubs against the stimulated site, and there is rhythmic alternation between hip protractor and hip retractor muscle activity (Robertson et al., 1985). In a rostral scratch, the monoarticular knee extensor muscle is active during the latter portion of hip protractor muscle activity; in a caudal scratch, the monoarticular knee extensor muscle is active near the end of hip retractor muscle activity. Pure-form motor patterns that are similar to those recorded from these muscles during movement can be recorded from the corresponding nerves in a spinal turtle immobilized with a neuromuscular blocking agent (Robertson et al., 1985). In this paper, we describe blend responses to simultaneous stimulation of 2 sites, one in the rostral scratch and the other in the caudal scratch receptive field. During these blends, the responding hindlimb rubs against both stimulated sites in one continuous movement sequence.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3746408

  8. Patterning of somatosympathetic reflexes

    NASA Technical Reports Server (NTRS)

    Kerman, I. A.; Yates, B. J.

    1999-01-01

    In a previous study, we reported that vestibular nerve stimulation in the cat elicits a specific pattern of sympathetic nerve activation, such that responses are particularly large in the renal nerve. This patterning of vestibulosympathetic reflexes was the same in anesthetized and decerebrate preparations. In the present study, we report that inputs from skin and muscle also elicit a specific patterning of sympathetic outflow, which is distinct from that produced by vestibular stimulation. Renal, superior mesenteric, and lumbar colonic nerves respond most strongly to forelimb and hindlimb nerve stimulation (approximately 60% of maximal nerve activation), whereas external carotid and hypogastric nerves were least sensitive to these inputs (approximately 20% of maximal nerve activation). In contrast to vestibulosympathetic reflexes, the expression of responses to skin and muscle afferent activation differs in decerebrate and anesthetized animals. In baroreceptor-intact animals, somatosympathetic responses were strongly attenuated (to <20% of control in every nerve) by increasing blood pressure levels to >150 mmHg. These findings demonstrate that different types of somatic inputs elicit specific patterns of sympathetic nerve activation, presumably generated through distinct neural circuits.

  9. Solar Power Satellite Microwave Transmission and Reception

    NASA Technical Reports Server (NTRS)

    Dietz, R. H.

    1980-01-01

    Numerous analytical and experimental investigations related to SPS microwave power transmission and reception are reported. Aspects discussed include system performance, phase control, power amplifiers, radiating elements, rectenna, solid state configurations, and planned program activities.

  10. Satellite sound broadcasting system, portable reception

    NASA Technical Reports Server (NTRS)

    Golshan, Nasser; Vaisnys, Arvydas

    1990-01-01

    Studies are underway at JPL in the emerging area of Satellite Sound Broadcast Service (SSBS) for direct reception by low cost portable, semi portable, mobile and fixed radio receivers. This paper addresses the portable reception of digital broadcasting of monophonic audio with source material band limited to 5 KHz (source audio comparable to commercial AM broadcasting). The proposed system provides transmission robustness, uniformity of performance over the coverage area and excellent frequency reuse. Propagation problems associated with indoor portable reception are considered in detail and innovative antenna concepts are suggested to mitigate these problems. It is shown that, with the marriage of proper technologies a single medium power satellite can provide substantial direct satellite audio broadcast capability to CONUS in UHF or L Bands, for high quality portable indoor reception by low cost radio receivers.

  11. Teaching Reflexivity in Qualitative Interviewing

    ERIC Educational Resources Information Center

    Hsiung, Ping-Chun

    2008-01-01

    Reflexivity has gained paramount status in qualitative inquiry. It is central to debates on subjectivity, objectivity, and, ultimately, the scientific foundation of social science knowledge and research. Although much work on doing reflexivity by researchers and practitioners has been published, scholars have only recently begun to explore how one…

  12. Reflexive Planning for Later Life

    ERIC Educational Resources Information Center

    Denton, Margaret A.; Kemp, Candace L.; French, Susan; Gafni, Amiram; Joshi, Anju; Rosenthal, Carolyn J.; Davies, Sharon

    2004-01-01

    Informed by Giddens' (1991) concept of "reflexive life" planning and the notion of later life as a time of increasing social and financial risk, this research explores the idea of "reflexive planning for later life". We utilize a conceptual model that incorporates three types of planning for later life: public protection, self-insurance, and…

  13. Developmental adaptation of withdrawal reflexes to early alteration of peripheral innervation in the rat.

    PubMed Central

    Holmberg, H; Schouenborg, J

    1996-01-01

    1. In adult decerebrate spinal rats whose plantar nerves (PLN) had been transected at either postnatal day 1 (P1) or P21 the nociceptive withdrawal reflexes (NWR) of musculi extensor digitorum longus (EDL), peroneus longus (PER) and semitendinosus (ST) were characterized with respect to receptive field (RF) organization, magnitude and time course, using electromyography. Thermal (short CO2 laser pulses) and mechanical (calibrated pinch) stimulation were used. The innervation patterns in normal and lesioned adult rats were assessed by acute nerve lesions. 2. The spatial organization of the mean mechano- and thermonociceptive RFs of all the muscles studied was similar to normal in both P1- and P21-lesioned rats, although in some P21-lesioned rats atypical EDL RFs were encountered. 3. In P1-lesioned rats thermo-NWR of PER and EDL had normal magnitudes, while mechano-NWR were reduced. In P21-lesioned rats both thermo- and mechano-NWR of these muscles had reduced magnitudes. Except for thermo-NWR of ST in P1-lesioned rats, which were increased, NWR of ST had normal magnitudes in both P1- and P21-lesioned rats. The time course of thermonociceptive NWR of the muscles studied were near normal in both P1- and P21-lesioned rats. 4. Acute nerve lesions in adult P1-lesioned rats revealed an essentially abolished contribution to NWR from the PLN. Instead, the contribution to NWR from other hindpaw nerves, such as the superficial and deep peroneal nerves, was dramatically increased. By contrast, in P21-lesioned rats, the regenerated PLN contributed significantly to the NWR. 5. It is concluded that despite profound alterations of plantar hindpaw innervation induced by early PLN transection the cutaneous nociceptive input to NWR attained an essentially normal spatial organization. An experience-dependent mechanism is suggested to be instrumental in adapting the reflex connectivity to the peripheral innervation. Images Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 PMID

  14. Leading-edge receptivity for blunt-nose bodies

    NASA Technical Reports Server (NTRS)

    Kerschen, Edward J.

    1991-01-01

    This research program investigates boundary-layer receptivity in the leading-edge region for bodies with blunt leading edges. Receptivity theory provides the link between the unsteady distrubance environment in the free stream and the initial amplitudes of the instability waves in the boundary layer. This is a critical problem which must be addressed in order to develop more accurate prediction methods for boundary-layer transition. The first phase of this project examines the effects of leading-edge bluntness and aerodynamic loading for low Mach number flows. In the second phase of the project, the investigation is extended to supersonic Mach numbers. Singular perturbation techniques are utilized to develop an asymptotic theory for high Reynolds numbers. In the first year, the asymptotic theory was developed for leading-edge receptivity in low Mach number flows. The case of a parabolic nose is considered. Substantial progress was made on the Navier-Sotkes computations. Analytical solutions for the steady and unsteady potential flow fields were incorporated into the code, greatly expanding the types of free-stream disturbances that can be considered while also significantly reducing the the computational requirements. The time-stepping algorithm was modified so that the potential flow perturbations induced by the unsteady pressure field are directly introduced throughout the computational domain, avoiding an artificial 'numerical diffusion' of these from the outer boundary. In addition, the start-up process was modified by introducing the transient Stokes wave solution into the downstream boundary conditions.

  15. Reflex myoclonus in olivopontocerebellar atrophy.

    PubMed Central

    Rodriguez, M E; Artieda, J; Zubieta, J L; Obeso, J A

    1994-01-01

    The presence of reflex myoclonus in response to touching and pin-pricking the wrist or stretching the fingers and to photic stimulation was assessed in 24 patients with a presumed diagnosis of olivopontocerebellar atrophy (OPCA) and in 30 age matched control subjects. Reflex myoclonus to soma-esthetic stimulation was found in 23 patients and in none of the controls. Photic myoclonus was present in 12 patients and in none of the controls. Electrophysiological study of the reflex myoclonus showed enhanced (> 10 microV) somatosensory evoked potentials and an associated reflex electromyographic discharge (C-wave) in 15 patients. These findings indicate that reflex myoclonus is common in OPCA and probably of cortical origin. Images PMID:8158179

  16. [Reflex seizures, cinema and television].

    PubMed

    Olivares-Romero, Jesús

    2015-12-16

    In movies and television series are few references to seizures or reflex epilepsy even though in real life are an important subgroup of total epileptic syndromes. It has performed a search on the topic, identified 25 films in which they appear reflex seizures. Most seizures observed are tonic-clonic and visual stimuli are the most numerous, corresponding all with flashing lights. The emotions are the main stimuli in higher level processes. In most cases it is not possible to know if a character suffers a reflex epilepsy or suffer reflex seizures in the context of another epileptic syndrome. The main conclusion is that, in the movies, the reflex seizures are merely a visual reinforcing and anecdotal element without significant influence on the plot. PMID:26662874

  17. Acoustic reflex and general anaesthesia.

    PubMed

    Farkas, Z

    1983-01-01

    Infant and small children are not always able to cooperate in impedance measurements. For this reason it was decided, -in special cases, -to perform acoustic reflex examination under general anaesthesia. The first report on stapedius reflex and general anaesthesia was published by Mink et al. in 1981. Under the effect of Tiobutabarbital, Propanidid and Diazepam there is no reflex response. Acoustic reflex can be elicited with Ketamin-hydrochlorid and Alphaxalone-alphadolone acetate narcosis. The reflex threshold remains unchanged and the amplitude of muscle contraction is somewhat increased. The method was used: 1. to assess the type and degree of hearing loss in children with cleft palate and/or lip prior to surgery. 2. to exclude neuromuscular disorders with indication of pharyngoplasties. 3. to quantify hearing level in children--mostly multiply handicapped--with retarded speech development. The results of Behavioral Observation and Impedance Audiometry are discussed and evaluated.

  18. [Reflex seizures, cinema and television].

    PubMed

    Olivares-Romero, Jesús

    2015-12-16

    In movies and television series are few references to seizures or reflex epilepsy even though in real life are an important subgroup of total epileptic syndromes. It has performed a search on the topic, identified 25 films in which they appear reflex seizures. Most seizures observed are tonic-clonic and visual stimuli are the most numerous, corresponding all with flashing lights. The emotions are the main stimuli in higher level processes. In most cases it is not possible to know if a character suffers a reflex epilepsy or suffer reflex seizures in the context of another epileptic syndrome. The main conclusion is that, in the movies, the reflex seizures are merely a visual reinforcing and anecdotal element without significant influence on the plot.

  19. 33 CFR 158.420 - Reception facilities: Capacity and exceptions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND GARBAGE Criteria for Adequacy of Reception Facilities: Garbage § 158.420 Reception facilities:...

  20. 33 CFR 158.420 - Reception facilities: Capacity and exceptions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND GARBAGE Criteria for Adequacy of Reception Facilities: Garbage § 158.420 Reception facilities:...

  1. 33 CFR 158.420 - Reception facilities: Capacity and exceptions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND GARBAGE Criteria for Adequacy of Reception Facilities: Garbage § 158.420 Reception facilities:...

  2. 33 CFR 158.420 - Reception facilities: Capacity and exceptions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND GARBAGE Criteria for Adequacy of Reception Facilities: Garbage § 158.420 Reception facilities:...

  3. 33 CFR 158.420 - Reception facilities: Capacity and exceptions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND GARBAGE Criteria for Adequacy of Reception Facilities: Garbage § 158.420 Reception facilities:...

  4. Encouraging Reflexivity in Urban Geography Fieldwork: Study Abroad Experiences in Singapore and Malaysia

    ERIC Educational Resources Information Center

    Glass, Michael R.

    2014-01-01

    Fieldwork in urban geography courses can encourage reflexivity among students regarding the cities they encounter. This article outlines how student reflexivity was encouraged within a new international field research course in Singapore and Malaysia. Drawing on examples from students' field exercises written during an intensive and…

  5. Stigmatic receptivity determines the seed set in Indian mustard, rice and wheat crops.

    PubMed

    Gupta, Ramwant; Sutradhar, Hrishikesh; Chakrabarty, S K; Ansari, Mohhammed Wahid; Singh, Yogendra

    2015-01-01

    Stigmatic receptivity restricts the successful pollination in cereal crops. The present study deals with the biochemical test for enzymes producing in stigma of field crops such as Indian mustard, rice and wheat. The alcohol dehydrogenase and hydrogen peroxide assays revealed stigmatic receptivity as a violet color and oxygen bubbles released by the chemical reaction. Therefore, the 2 quick tests are in conformity to each other and supported the seed set data, which was utmost at blooming stage of flower ranged between 2-4 d All the 3 crops showed variation in stigmatic receptivity with respect to different time periods of blooming stages and hence, it may affects simultaneous pollen germination and tube growth, fertilization and seed set. The present finding suggests that the growth of pollen tube and stigma receptivity could be influenced by specific enzymes on stigma surface after 2-4 d of blooming stage, which contributes to proper seed set. PMID:27066163

  6. ["Reflex--in a strict sense". Ivan Michajlovic Secenov and the founding myths of the 'Russian reflex empire'].

    PubMed

    Wurm, Barbara

    2009-03-01

    This paper aims to reconstruct Ivan Michajlovik Secenov's impact on reflex theory by looking at the different narratives which constitute his specific position in the history of science, where he is considered the Russian founder of a purely materialist framing of consciousness and behaviour, the father figure of objective psychology, and the predecessor of the 'great' Ivan Pavlov. I argue that Secenov himself was very much aware of the symbolic significance of the term "reflex" and that the rhetorical strategies in his opus magnum, The Reflexes of the Brain (1863), deliberately enforce the precarious twofold potential of reflexological conceptions as psycho-physiological structures as well as social programs. Also within the cultural and political settings of the 19th and 20th century, Secenov's comprehensive and multifaceted research work in the field of nerve physiology was gradually reduced to a strong, ideologically interpretable message: "All movements bearing the name of voluntary in physiology are reflex in a strict sense".

  7. ["Reflex--in a strict sense". Ivan Michajlovic Secenov and the founding myths of the 'Russian reflex empire'].

    PubMed

    Wurm, Barbara

    2009-03-01

    This paper aims to reconstruct Ivan Michajlovik Secenov's impact on reflex theory by looking at the different narratives which constitute his specific position in the history of science, where he is considered the Russian founder of a purely materialist framing of consciousness and behaviour, the father figure of objective psychology, and the predecessor of the 'great' Ivan Pavlov. I argue that Secenov himself was very much aware of the symbolic significance of the term "reflex" and that the rhetorical strategies in his opus magnum, The Reflexes of the Brain (1863), deliberately enforce the precarious twofold potential of reflexological conceptions as psycho-physiological structures as well as social programs. Also within the cultural and political settings of the 19th and 20th century, Secenov's comprehensive and multifaceted research work in the field of nerve physiology was gradually reduced to a strong, ideologically interpretable message: "All movements bearing the name of voluntary in physiology are reflex in a strict sense". PMID:19824305

  8. The vestibulosympathetic reflex in humans: neural interactions between cardiovascular reflexes

    NASA Technical Reports Server (NTRS)

    Ray, Chester A.; Monahan, Kevin D.

    2002-01-01

    1. Over the past 5 years, there has been emerging evidence that the vestibular system regulates sympathetic nerve activity in humans. We have studied this issue in humans by using head-down rotation (HDR) in the prone position. 2. These studies have clearly demonstrated increases in muscle sympathetic nerve activity (MSNA) and calf vascular resistance during HDR. These responses are mediated by engagement of the otolith organs and not the semicircular canals. 3. However, differential activation of sympathetic nerve activity has been observed during HDR. Unlike MSNA, skin sympathetic nerve activity does not increase with HDR. 4. Examination of the vestibulosympathetic reflex with other cardiovascular reflexes (i.e. barorereflexes and skeletal muscle reflexes) has shown an additive interaction for MSNA. 5. The additive interaction between the baroreflexes and vestibulosympathetic reflex suggests that the vestibular system may assist in defending against orthostatic challenges in humans by elevating MSNA beyond that of the baroreflexes. 6. In addition, the further increase in MSNA via otolith stimulation during isometric handgrip, when arterial pressure is elevated markedly, indicates that the vestibulosympathetic reflex is a powerful activator of MSNA and may contribute to blood pressure and flow regulation during dynamic exercise. 7. Future studies will help evaluate the importance of the vestibulosympathetic reflex in clinical conditions associated with orthostatic hypotension.

  9. Vestibulo-spinal reflex mechanisms

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.

    1981-01-01

    The specific objectives of experiments designed to investigate postural reflex behavior during sustained weightlessness are discussed. The first is to investigate, during prolonged weightlessness with Hoffmann response (H-reflex) measurement procedures, vestibulo-spinal reflexes associated with vestibular (otolith) responses evoked during an applied linear acceleration. This objective includes not only an evaluation of otolith-induced changes in a major postural muscle but also an investigation with this technique of the adaptive process of the vestibular system and spinal reflex mechanisms to this unique environment. The second objective is to relate space motion sickness to the results of this investigation. Finally, a return to the vestibulo-spinal and postural reflexes to normal values following the flight will be examined. The flight experiment involves activation of nerve tissue (tibial N) with electrical shock and the recording of resulting muscle activity (soleus) with surface electrodes. Soleus/spinal H-reflex testing procedures will be used in conjuction with linear acceleration through the subject's X-axis.

  10. Acoustic receptivity of compressible boundary layers: Receptivity by way of surface-temperature variations

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan

    1994-01-01

    The Goldstein-Ruban theory has been extended within the framework of Zavol'skii et al. to study the acoustic receptivity of compressible boundary layers. We consider the receptivity produced in a region of localized, small-amplitude variation in the surface temperature and compare it with the receptivity that is induced through a similar mechanism by a variation in the suction velocity at the surface. It is found that the orientation of the acoustic wave can have a significant impact on the receptivity process, with the maximum receptivity at a given sound-pressure level being produced by upstream oriented acoustic waves. At sufficiently low Mach numbers, the variation of receptivity with the acoustic-wave orientation can be predicted analytically and is the same for both surface suction and surface heating. However, as a result of the acoustic refraction across the mean boundary layer, the above dependence can become rather complex and, also, dependent on the type of surface nonuniformity. The results also suggest that the receptivity caused by temperature nonuniformities may turn out to be more significant than that produced by the mean-flow perturbations associated with strip suction.

  11. Learning reflexively from a health promotion professional development program in Canada.

    PubMed

    Tremblay, Marie-Claude; Richard, Lucie; Brousselle, Astrid; Beaudet, Nicole

    2014-09-01

    In recent decades, reflexivity has received much attention in the professional education and training literature, especially in the public health and health promotion fields. Despite general agreement on the importance of reflexivity, there appears to be no consensus on how to assess reflexivity or to conceptualize the different forms developed among professionals and participants of training programs. This paper presents an analysis of the reflexivity outcomes of the Health Promotion Laboratory, an innovative professional development program aimed at supporting practice changes among health professionals by fostering competency development and reflexivity. More specifically, this paper explores the difference between two levels of reflexivity (formative and critical) and highlights some implications of each for practice. Data were collected through qualitative interviews with participants from two intervention sites. Results showed that involvement in the Health Promotion Laboratory prompted many participants to modify their vision of their practice and professional role, indicating an impact on reflexivity. In many cases, new understandings seem to have played a formative function in enabling participants to improve their practice and their role as health promoters. The reflective process also served a critical function culminating in a social and moral understanding of the impacts on society of the professionals' practices and roles. This type of outcome is greatly desired in health promotion, given the social justice and equity concerns of this field of practice. By redefining the theoretical concept of reflexivity on two levels and discussing their impacts on practice, this study supports the usefulness of both levels of reflexivity.

  12. Poor Reception for Broadcast Graduates

    ERIC Educational Resources Information Center

    Carlisle, Robert D. B.

    1976-01-01

    Noting reports of 17,251 college juniors and seniors majoring in radio-television broadcasting and only 141,500 employees now working in the field, the author discusses the causes and implications including the value of the radio-TV degree and the cost of broadcast education. (JT)

  13. Reflexivity and the Politics of Knowledge: Researchers as "Brokers" and "Translators" of Educational Development

    ERIC Educational Resources Information Center

    Sriprakash, Arathi; Mukhopadhyay, Rahul

    2015-01-01

    This paper interrogates the ways in which "reflexivity" has proliferated as a normative methodological discourse in the field of international and comparative education. We argue that the dominant approach to reflexivity foregrounds the standpoints of researchers and their subjects in a way that does not attend to the situated,…

  14. Testing the Receptive Skills: Some Basic Considerations.

    ERIC Educational Resources Information Center

    Jones, Randall L.

    1984-01-01

    Reacts to Michael Canale's paper, "Considerations in the Testing of Reading and Listening Proficiency," concentrating on three areas: (1) the nature of the receptive skills and the requirements of a valid instrument to measure them, (2) the design features that are consistent with his test design principles, and (3) adaptive testing procedures.…

  15. Practical Considerations in Receptive Skills Testing.

    ERIC Educational Resources Information Center

    Liskin-Gasparro, Judith E.

    1984-01-01

    Discusses Michael Canale's paper, "Considerations in the Testing of Reading and Listening Proficiency," focusing on the third section, "Suggestions for improvements in receptive language testing." Considers such areas as: (1) level descriptions for academic use, (2) item and item types, and (3) validation. (SED)

  16. Comprehensive Hearing Impaired Reception Program; Spring, 1975.

    ERIC Educational Resources Information Center

    Oxman, Wendy G.

    This document presents a description and evaluation of the Comprehensive Hearing Impaired Reception Program (CHIRP). This program was designed to improve effective communication skills for hearing handicapped students whose native language was not English, and whose language deficiencies prevented them from effective participation in the learning…

  17. Language, gay pornography, and audience reception.

    PubMed

    Leap, William L

    2011-01-01

    Erotic imagery is an important component of gay pornographic cinema, particularly, where work of audience reception is concerned. However, to assume the audience engagement with the films is limited solely to the erotic realm is to underestimate the workings of ideological power in the context and aftermath of reception. For example, the director of the film under discussion here (Men of Israel; Lucas, 2009b) intended to present an erotic celebration of the nation-state. Yet, most viewers ignore the particulars of context in their comments about audience reception, placing the "Israeli" narrative within a broader framework, using transnational rather than film-specific criteria to guide their "reading" of the Israeli-centered narrative. This article uses as its entry point the language that viewers employ when describing their reactions to Men of Israel on a gay video club's Web site; this article shows how the work of audience reception may draw attention to a film's erotic details while invoking social and political messages that completely reframe the film's erotic narrative. PMID:21740219

  18. An integral sunshade for optical reception antennas

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1988-01-01

    Optical reception antennas (telescopes) must be capable of receiving communications even when the deep-space laser source is located within a small angle of the Sun. Direst sunlight must not be allowed to shine on the primary reflector of an optical reception antenna, because too much light would be scattered into the signal detectors. A conventional sunshade that does not obstruct the antenna aperture would have to be about five times longer than its diameter in order to receive optical communications at a solar elongation of 12 degrees without interference. Such a long sunshade could not be accommodated within the dome of any existing large-aperture astronomical facility, and providing a new dome large enough would be prohibitively expensive. It is also desirable to reduce the amount of energy a space-based large-aperture optical reception facility would expend orienting a structure with such a sizable moment of inertia. Since a large aperture optical reception antenna will probably have a hexagonally segmented primary reflector, a sunshade consisting of hexagonal tubes can be mounted in alignment with the segmentation without producing any additional geometric obstruction. An analysis of the duration and recurrence of solar-conjunction communications outages (caused when a deep-space probe near an outer planet appears to be closer to the Sun than a given minimum solar elongation), and the design equations for the integral sunshade are appended.

  19. Receptive Multilingualism in the Swiss Army

    ERIC Educational Resources Information Center

    Berthele, Raphael; Wittlin, Gabriele

    2013-01-01

    In this paper a particular context where receptive multilingualism at work can be observed is discussed. The Swiss armed forces underwent a series of quite dramatic downsizing measures, which lead to a situation with increased amount of mixed groups and linguistically mixed situations regarding the first/native language of officers and the…

  20. Rethinking Role Play in the Reception Class

    ERIC Educational Resources Information Center

    Rogers, Sue; Evans, Julie

    2007-01-01

    Background: In 2000 the so-called "Reception" class was re-conceived (in curricular terms, at least) as the second and final year of the Foundation Stage, a distinctive educational phase for children aged 3 until entry to key stage 1 at 5 or 6 years old. The "Curriculum guidance for the Foundation Stage" endorses a play-based, informal curriculum…

  1. Receptivity in parallel flows: An adjoint approach

    NASA Technical Reports Server (NTRS)

    Hill, D. Christopher

    1993-01-01

    Linear receptivity studies in parallel flows are aimed at understanding how external forcing couples to the natural unstable motions which a flow can support. The vibrating ribbon problem models the original Schubauer and Skramstad boundary layer experiment and represents the classic boundary layer receptivity problem. The process by which disturbances are initiated in convectively-unstable jets and shear layers has also received attention. Gaster was the first to handle the boundary layer analysis with the recognition that spatial modes, rather than temporal modes, were relevant when studying convectively-unstable flows that are driven by a time-harmonic source. The amplitude of the least stable spatial mode, far downstream of the source, is related to the source strength by a coupling coefficient. The determination of this coefficient is at the heart of this type of linear receptivity study. The first objective of the present study was to determine whether the various wave number derivative factors, appearing in the coupling coefficients for linear receptivity problems, could be reexpressed in a simpler form involving adjoint eigensolutions. Secondly, it was hoped that the general nature of this simplification could be shown; indeed, a rather elegant characterization of the receptivity properties of spatial instabilities does emerge. The analysis is quite distinct from the usual Fourier-inversion procedures, although a detailed knowledge of the spectrum of the Orr-Sommerfeld equation is still required. Since the cylinder wake analysis proved very useful in addressing control considerations, the final objective was to provide a foundation upon which boundary layer control theory may be developed.

  2. 33 CFR 158.320 - Reception facilities: Capacity, and exceptions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND... Residue § 158.320 Reception facilities: Capacity, and exceptions. (a) Except as allowed in paragraph...

  3. 33 CFR 158.320 - Reception facilities: Capacity, and exceptions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND... Residue § 158.320 Reception facilities: Capacity, and exceptions. (a) Except as allowed in paragraph...

  4. 33 CFR 158.320 - Reception facilities: Capacity, and exceptions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND... Residue § 158.320 Reception facilities: Capacity, and exceptions. (a) Except as allowed in paragraph...

  5. 33 CFR 158.320 - Reception facilities: Capacity, and exceptions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND... Residue § 158.320 Reception facilities: Capacity, and exceptions. (a) Except as allowed in paragraph...

  6. 33 CFR 158.320 - Reception facilities: Capacity, and exceptions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Reception facilities: Capacity... HOMELAND SECURITY (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND... Residue § 158.320 Reception facilities: Capacity, and exceptions. (a) Except as allowed in paragraph...

  7. A Hierarchy of Temporal Receptive Windows in Human Cortex

    PubMed Central

    Hasson, Uri; Yang, Eunice; Vallines, Ignacio; Heeger, David J.; Rubin, Nava

    2008-01-01

    Real-world events unfold at different time scales and, therefore, cognitive and neuronal processes must likewise occur at different time scales. We present a novel procedure that identifies brain regions responsive to sensory information accumulated over different time scales. We measured functional magnetic resonance imaging activity while observers viewed silent films presented forward, backward, or piecewise-scrambled in time. Early visual areas (e.g., primary visual cortex and the motion-sensitive area MT+) exhibited high response reliability regardless of disruptions in temporal structure. In contrast, the reliability of responses in several higher brain areas, including the superior temporal sulcus (STS), precuneus, posterior lateral sulcus (LS), temporal parietal junction (TPJ), and frontal eye field (FEF), was affected by information accumulated over longer time scales. These regions showed highly reproducible responses for repeated forward, but not for backward or piecewise-scrambled presentations. Moreover, these regions exhibited marked differences in temporal characteristics, with LS, TPJ, and FEF responses depending on information accumulated over longer durations (~36 s) than STS and precuneus (~12 s). We conclude that, similar to the known cortical hierarchy of spatial receptive fields, there is a hierarchy of progressively longer temporal receptive windows in the human brain. PMID:18322098

  8. Spanish Reflexives: A Critique of Pedagogical Descriptions.

    ERIC Educational Resources Information Center

    Lozano, Anthony G.

    1997-01-01

    Discusses pedagogical descriptions in high school textbooks covering Spanish reflexive verb constructions. Points out that these textbooks rarely contain the full reflexive construction displayed with all the grammatical persons and complete English glosses. (17 references) (Author/CK)

  9. Graphic Sequences of Spanish Nominals and Reflexives.

    ERIC Educational Resources Information Center

    Lozano, Anthony G.

    1993-01-01

    The use of graphics for clarifying paradigmatic and syntagmatic relationships of nominals is described. This approach improves student understanding of reflexive, pseudo-reflexive, and nonreflexive sequences. (Contains seven references.) (Author/LB)

  10. Reflexivity: a methodological tool in the knowledge translation process?

    PubMed

    Alley, Sarah; Jackson, Suzanne F; Shakya, Yogendra B

    2015-05-01

    Knowledge translation is a dynamic and iterative process that includes the synthesis, dissemination, exchange, and application of knowledge. It is considered the bridge that closes the gap between research and practice. Yet it appears that in all areas of practice, a significant gap remains in translating research knowledge into practical application. Recently, researchers and practitioners in the field of health care have begun to recognize reflection and reflexive exercises as a fundamental component to the knowledge translation process. As a practical tool, reflexivity can go beyond simply looking at what practitioners are doing; when approached in a systematic manner, it has the potential to enable practitioners from a wide variety of backgrounds to identify, understand, and act in relation to the personal, professional, and political challenges they face in practice. This article focuses on how reflexive practice as a methodological tool can provide researchers and practitioners with new insights and increased self-awareness, as they are able to critically examine the nature of their work and acknowledge biases, which may affect the knowledge translation process. Through the use of structured journal entries, the nature of the relationship between reflexivity and knowledge translation was examined, specifically exploring if reflexivity can improve the knowledge translation process, leading to increased utilization and application of research findings into everyday practice.

  11. Caught in Uncertain Futures, Now: A Reflexive Moment

    ERIC Educational Resources Information Center

    Reyes, Reynaldo, III

    2016-01-01

    This reflexive vignette reveals the emotional risks of ethnographic work by a Chicano researcher, educator, and advocate doing work in the Texas-Mexico Borderlands, caught at the intersection of vulnerable Latina/o youth and their possible futures. Data in this creative piece are derived from field notes of one classroom observation from an…

  12. [Clinical relevance of cardiopulmonary reflexes in anesthesiology].

    PubMed

    Guerri-Guttenberg, R A; Siaba-Serrate, F; Cacheiro, F J

    2013-10-01

    The baroreflex, chemoreflex, pulmonary reflexes, Bezold-Jarisch and Bainbridge reflexes and their interaction with local mechanisms, are a demonstration of the richness of cardiovascular responses that occur in human beings. As well as these, the anesthesiologist must contend with other variables that interact by attenuating or accentuating cardiopulmonary reflexes such as, anesthetic drugs, surgical manipulation, and patient positioning. In the present article we review these reflexes and their clinical relevance in anesthesiology.

  13. Reflexive and Reciprocal Elements in Ixil.

    ERIC Educational Resources Information Center

    Ayres, Glenn

    1990-01-01

    Reflexives and reciprocals in Ixil, a Mayan language of Guatemala, appear to have features that distinguish them from reflexives surveyed in typological studies such as Faltz (1985) and Geniusiene (1987). Third person reflexives and reciprocals seem to have the form of a possessed noun optionally followed by a possessor NP. Moreover, reflexives…

  14. Effects of fixation and optokinetic stimulation on vestibulo-ocular reflex suppression.

    PubMed Central

    Chambers, B R; Gresty, M A

    1982-01-01

    Suppression of the vestibulo-ocular reflex was assessed in normal subjects and patients with neurological disorders to determine the relative effects on suppression of a single fixation target and an optokinetic field. Subjects were rotated sinusoidally in yaw at varying frequencies of up to 0.5 Hz whilst seated in a Barany chair. A comparison was made between eye movements in darkness, those produced during fixation on a central target mounted to the chair, and eye movements during fixation on the target plus an "earth-fixed" or "chair-fixed" visual background. Presentation of a background produced only minimal effects on the suppression of the vestibulo-ocular reflex in normal subjects. In patients with impairment of fixation suppression, suppression of the vestibulo-ocular reflex was not improved after presentation of either form of optokinetic field. The results demonstrate that central fixation is the predominant requirement for suppression of the vestibulo-ocular reflex. This correlates closely with the ability to pursue. Although the optokinetic reflex generates following eye movements similar to pursuit, it cannot be used to mediate suppression of the vestibulo-ocular reflex in the absence of an intact pursuit system. The findings strengthen the view that the optokinetic reflex evolved to act in synergy with the vestibulo-ocular reflex in generating compensatory eye movements. Images PMID:7175543

  15. Eugen Bleuler 150: Bleuler's reception of Freud.

    PubMed

    Dalzell, Thomas G

    2007-12-01

    On the 150th anniversary of Eugen Bleuler's birth, this article examines his reception of Sigmund Freud and his use of Freudian theory to understand the symptoms of schizophrenia. In addition, in contrast to earlier interpretations of Bleuler's relationship with Freud in terms of an eventual personal and theoretical incompatibility, the article demonstrates that, although Bleuler did distance himself from the psychoanalytic movement, he remained consistent in his views on Freud's theories.

  16. Charging for port reception facilities in North Sea ports: putting theory into practice.

    PubMed

    Carpenter, A; Macgill, S

    2001-04-01

    The aim of this paper is to evaluate the charging systems for the use of port reception facilities for waste oil, and to examine the potential impact of the charging elements of the new (late 2000) EU Directive on port reception facilities for ship-generated waste and cargo residues. Experience to date with alternative models for charging is considered. Conclusions are drawn about the effectiveness of the EU Directive as a means of controlling pollution in the North Sea and producing a 'level playing field' between ports.

  17. Characterization of the Transcriptional Complexity of the Receptive and Pre-receptive Endometria of Dairy Goats

    PubMed Central

    Zhang, Lei; An, Xiao-Peng; Liu, Xiao-Rui; Fu, Ming-Zhe; Han, Peng; Peng, Jia-Yin; Hou, Jing-Xing; Zhou, Zhan-Qin; Cao, Bin-Yun; Song, Yu-Xuan

    2015-01-01

    Endometrium receptivity is essential for successful embryo implantation in mammals. However, the lack of genetic information remains an obstacle to understanding the mechanisms underlying the development of a receptive endometrium from the pre-receptive phase in dairy goats. In this study, more than 4 billion high-quality reads were generated and de novo assembled into 102,441 unigenes; these unigenes were annotated using published databases. A total of 3,255 unigenes that were differentially expressed (DEGs) between the PE and RE were discovered in this study (P-values < 0.05). In addition, 76,729–77,102 putative SNPs and 12,837 SSRs were discovered in this study. Bioinformatics analysis of the DEGs revealed a number of biological processes and pathways that are potentially involved in the establishment of the RE, notably including the GO terms proteolysis, apoptosis, and cell adhesion and the KEGG pathways Cell cycle and extracellular matrix (ECM)-receptor interaction. We speculated that ADCY8, VCAN, SPOCK1, THBS1, and THBS2 may play important roles in the development of endometrial receptivity. The de novo assembly provided a good starting point and will serve as a valuable resource for further investigations into endometrium receptivity in dairy goats and future studies on the genomes of goats and other related mammals. PMID:26373443

  18. Receptivity of Hypersonic Boundary Layers over Straight and Flared Cones

    NASA Technical Reports Server (NTRS)

    Balakumar, Ponnampalam; Kegerise, Michael A.

    2010-01-01

    The effects of adverse pressure gradients on the receptivity and stability of hypersonic boundary layers were numerically investigated. Simulations were performed for boundary layer flows over a straight cone and two flared cones. The steady and the unsteady flow fields were obtained by solving the two-dimensional Navier-Stokes equations in axi-symmetric coordinates using the 5th order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. The mean boundary layer profiles were analyzed using local stability and non-local parabolized stability equations (PSE) methods. After the most amplified disturbances were identified, two-dimensional plane acoustic waves were introduced at the outer boundary of the computational domain and time accurate simulations were performed. The adverse pressure gradient was found to affect the boundary layer stability in two important ways. Firstly, the frequency of the most amplified second-mode disturbance was increased relative to the zero pressure gradient case. Secondly, the amplification of first- and second-mode disturbances was increased. Although an adverse pressure gradient enhances instability wave growth rates, small nose-tip bluntness was found to delay transition due to the low receptivity coefficient and the resulting weak initial amplitude of the instability waves. The computed and measured amplitude-frequency spectrums in all three cases agree very well in terms of frequency and the shape except for the amplitude.

  19. Researching Reflexively With Patients and Families: Two Studies Using Video-Reflexive Ethnography to Collaborate With Patients and Families in Patient Safety Research.

    PubMed

    Collier, Aileen; Wyer, Mary

    2016-06-01

    Patient safety research has to date offered few opportunities for patients and families to be actively involved in the research process. This article describes our collaboration with patients and families in two separate studies, involving end-of-life care and infection control in acute care. We used the collaborative methodology of video-reflexive ethnography, which has been primarily used with clinicians, to involve patients and families as active participants and collaborators in our research. The purpose of this article is to share our experiences and findings that iterative researcher reflexivity in the field was critical to the progress and success of each study. We present and analyze the complexities of reflexivity-in-the-field through a framework of multilayered reflexivity. We share our lessons here for other researchers seeking to actively involve patients and families in patient safety research using collaborative visual methods.

  20. Photomultiplier reception of satellite beacon flashes.

    PubMed

    Abby, D G; Wirtanen, T E

    1969-03-01

    Experiments have been performed on the electrooptical detection of flashes from satellite-borne beacons for the purposes of establishing the time of flash at the observing site, measurement of received pulse shape, and relative measurement of received energy. Initial observations have been made of the beacons carried by the geodetic satellite GEOS-B. Time of flash has been obtained to a precision of 0.1 msec. Pulse shape and energy measurements have been made for various slant ranges and at various voltages on the photomultiplier circuits. Continued testing is directed toward microsecond timing of flash reception.

  1. Toward reflexive climate adaptation research

    SciTech Connect

    Preston, Benjamin L.; Rickards, Lauren; Fünfgeld, Hartmut; Keenan, Rodney J.

    2015-06-22

    Climate adaptation research is expanding very quickly within an increasingly reflexive society where the relationship between academia and other social institutions is in a state of flux. Tensions exist between the two dominant research orientations of research about and research for adaptation. In particular, the research community is challenged to develop processes for successfully executing transdisciplinary research for adaptation when academic institutions and researchers are largely structured around traditional, disciplinary expertise and funding models. One tool for helping to manage this tension is a third, more reflexive, orientation toward adaptation research that is emerging in the literature. Finally, this new ‘research on adaptation research’ promises to help enhance understanding of the research enterprise itself and how it can become more adaptive.

  2. Toward reflexive climate adaptation research

    DOE PAGES

    Preston, Benjamin L.; Rickards, Lauren; Fünfgeld, Hartmut; Keenan, Rodney J.

    2015-06-22

    Climate adaptation research is expanding very quickly within an increasingly reflexive society where the relationship between academia and other social institutions is in a state of flux. Tensions exist between the two dominant research orientations of research about and research for adaptation. In particular, the research community is challenged to develop processes for successfully executing transdisciplinary research for adaptation when academic institutions and researchers are largely structured around traditional, disciplinary expertise and funding models. One tool for helping to manage this tension is a third, more reflexive, orientation toward adaptation research that is emerging in the literature. Finally, this newmore » ‘research on adaptation research’ promises to help enhance understanding of the research enterprise itself and how it can become more adaptive.« less

  3. Vestibular reflexes of otolith origin

    NASA Technical Reports Server (NTRS)

    Wilson, Victor J.

    1988-01-01

    The vestibular system and its role in the maintenance of posture and in motion sickness is investigated using cats as experimental subjects. The assumption is that better understanding of the physiology of vestibular pathways is not only of intrinsic value, but will help to explain and eventually alleviate the disturbances caused by vestibular malfunction, or by exposure to an unusual environment such as space. The first project deals with the influence on the spinal cord of stimulation of the vestibular labyrinth, particularly the otoliths. A second was concerned with the properties and neural basis of the tonic neck reflex. These two projects are related, because vestibulospinal and tonic neck reflexes interact in the maintenance of normal posture. The third project began with an interest in mechanisms of motion sickness, and eventually shifted to a study of central control of respiratory muscles involved in vomiting.

  4. Human stretch reflex pathways reexamined

    PubMed Central

    Yavuz, Ş. Utku; Mrachacz-Kersting, Natalie; Sebik, Oğuz; Berna Ünver, M.; Farina, Dario

    2013-01-01

    Reflex responses of tibialis anterior motor units to stretch stimuli were investigated in human subjects. Three types of stretch stimuli were applied (tap-like, ramp-and-hold, and half-sine stretch). Stimulus-induced responses in single motor units were analyzed using the classical technique, which involved building average surface electromyogram (SEMG) and peristimulus time histograms (PSTH) from the discharge times of motor units and peristimulus frequencygrams (PSF) from the instantaneous discharge rates of single motor units. With the use of SEMG and PSTH, the tap-like stretch stimulus induced five separate reflex responses, on average. With the same single motor unit data, the PSF technique indicated that the tap stimulus induced only three reflex responses. Similar to the finding using the tap-like stretch stimuli, ramp-and-hold stimuli induced several peaks and troughs in the SEMG and PSTH. The PSF analyses displayed genuine increases in discharge rates underlying the peaks but not underlying the troughs. Half-sine stretch stimuli induced a long-lasting excitation followed by a long-lasting silent period in SEMG and PSTH. The increase in the discharge rate, however, lasted for the entire duration of the stimulus and continued during the silent period. The results are discussed in the light of the fact that the discharge rate of a motoneuron has a strong positive linear association with the effective synaptic current it receives and hence represents changes in the membrane potential more directly and accurately than the other indirect measures. This study suggests that the neuronal pathway of the human stretch reflex does not include inhibitory pathways. PMID:24225537

  5. MR imaging with remote reception using a coil array

    NASA Astrophysics Data System (ADS)

    Vazquez, F.; Marrufo, O.; Martin, R.; Rodriguez, A. O.

    2012-10-01

    A strategy for imaging a large field-of-view has recently been proposed applying remote detection with a waveguide and single loop coils. RF coils produce a traveling-wave propagating through the bore of the magnet, which is large enough so the cutoff frequency is below the Larmor frequency. This assumption also considers that a human subject inside the magnet bore. We applied the travelling-wave concept to generate images of a human leg at 3 Tesla. Two circular-shaped coils were used as the reception device and a whole-body coil was used for transmission. Images showed a good signal-to-noise ratio along the entire leg. This experimental results contradict the assumption that a whole-body 7T/65cm imager or higher was necessary to generate images with this approach.

  6. Receptivity to Bariatric Surgery in Qualified Patients.

    PubMed

    Fung, Michael; Wharton, Sean; Macpherson, Alison; Kuk, Jennifer L

    2016-01-01

    Objectives. Bariatric surgery has been shown to be an effective intervention for weight loss and diabetes management. Despite this, many patients qualified for bariatric surgery are not interested in undergoing the procedure. The objective of this study is to determine the factors influencing receptivity to bariatric surgery among those who qualify for the procedure. Methods. Patients attending a publicly funded weight management clinic who qualified for bariatric surgery were asked to complete an elective questionnaire between February 2013 and April 2014. Results. A total of 371 patients (72% female) completed the questionnaire. Only 87 of 371 (23%) participants were interested in bariatric surgery. Individuals interested in bariatric surgery had a higher BMI (48.0 versus 46.2 kg/m(2), P = 0.03) and believed that they would lose more weight with surgery (51 versus 44 kg, P = 0.0069). Those who scored highly on past weight loss success and financial concerns were less likely to be interested in bariatric surgery, whereas those who scored highly on high receptivity to surgery and positive social support were more likely to be interested in bariatric surgery. Conclusion. Although participants overestimated the effect of bariatric surgery on weight loss, most were still not interested in bariatric surgery. PMID:27516900

  7. Receptivity to Bariatric Surgery in Qualified Patients

    PubMed Central

    Fung, Michael; Wharton, Sean; Macpherson, Alison

    2016-01-01

    Objectives. Bariatric surgery has been shown to be an effective intervention for weight loss and diabetes management. Despite this, many patients qualified for bariatric surgery are not interested in undergoing the procedure. The objective of this study is to determine the factors influencing receptivity to bariatric surgery among those who qualify for the procedure. Methods. Patients attending a publicly funded weight management clinic who qualified for bariatric surgery were asked to complete an elective questionnaire between February 2013 and April 2014. Results. A total of 371 patients (72% female) completed the questionnaire. Only 87 of 371 (23%) participants were interested in bariatric surgery. Individuals interested in bariatric surgery had a higher BMI (48.0 versus 46.2 kg/m2, P = 0.03) and believed that they would lose more weight with surgery (51 versus 44 kg, P = 0.0069). Those who scored highly on past weight loss success and financial concerns were less likely to be interested in bariatric surgery, whereas those who scored highly on high receptivity to surgery and positive social support were more likely to be interested in bariatric surgery. Conclusion. Although participants overestimated the effect of bariatric surgery on weight loss, most were still not interested in bariatric surgery. PMID:27516900

  8. [Reflexivity: a critical issue in qualitative research].

    PubMed

    de la Cuesta-Benjumea, Carmen

    2011-01-01

    Reflexivity is an English term that Spanish speaking people have to assign a technical meaning. Reflexivity expresses the conscience of researchers conscience and refers to their connection with the study's situation. It is a process by which researchers step back to critically exam the effect they have on the study and the impact of their interactions with participants. The reflexive process is embedded in all research levels and is present in all the research phases, from the research question to fieldwork, from data analysis to writing the final report. Nevertheless, the question is not so much to engage in reflective activities but to be a reflexive researcher. Reflexivity is a human ability that is present during social interactions. For this reason it is present in qualitative research. A self inquirer can be addressed as it is constructed by the relationships and interactions that are established with study participants. Reflexivity has an educational character that continues after the study is completed. PMID:21531602

  9. Generalized versus partial reflex seizures: a review.

    PubMed

    Italiano, Domenico; Ferlazzo, Edoardo; Gasparini, Sara; Spina, Edoardo; Mondello, Stefania; Labate, Angelo; Gambardella, Antonio; Aguglia, Umberto

    2014-08-01

    In this review we assess our currently available knowledge about reflex seizures with special emphasis on the difference between "generalized" reflex seizures induced by visual stimuli, thinking, praxis and language tasks, and "focal" seizures induced by startle, eating, music, hot water, somatosensory stimuli and orgasm. We discuss in particular evidence from animal, clinical, neurophysiological and neuroimaging studies supporting the concept that "generalized" reflex seizures, usually occurring in the setting of IGE, should be considered as focal seizures with quick secondary generalization. We also review recent advances in genetic and therapeutic approach of reflex seizures.

  10. A method of reflexive balancing in a pragmatic, interdisciplinary and reflexive bioethics.

    PubMed

    Ives, Jonathan

    2014-07-01

    In recent years there has been a wealth of literature arguing the need for empirical and interdisciplinary approaches to bioethics, based on the premise that an empirically informed ethical analysis is more grounded, contextually sensitive and therefore more relevant to clinical practice than an 'abstract' philosophical analysis. Bioethics has (arguably) always been an interdisciplinary field, and the rise of 'empirical' (bio)ethics need not be seen as an attempt to give a new name to the longstanding practice of interdisciplinary collaboration, but can perhaps best be understood as a substantive attempt to engage with the nature of that interdisciplinarity and to articulate the relationship between the many different disciplines (some of them empirical) that contribute to the field. It can also be described as an endeavour to explain how different disciplinary approaches can be integrated to effectively answer normative questions in bioethics, and fundamental to that endeavour is the need to think about how a robust methodology can be articulated that successfully marries apparently divergent epistemological and metaethical perspectives with method. This paper proposes 'Reflexive Bioethics' (RB) as a methodology for interdisciplinary and empirical bioethics, which utilizes a method of 'Reflexive Balancing' (RBL). RBL has been developed in response to criticisms of various forms of reflective equilibrium, and is built upon a pragmatic characterization of Bioethics and a 'quasi-moral foundationalism', which allows RBL to avoid some of the difficulties associated with RE and yet retain the flexible egalitarianism that makes it intuitively appealing to many.

  11. A method of reflexive balancing in a pragmatic, interdisciplinary and reflexive bioethics.

    PubMed

    Ives, Jonathan

    2014-07-01

    In recent years there has been a wealth of literature arguing the need for empirical and interdisciplinary approaches to bioethics, based on the premise that an empirically informed ethical analysis is more grounded, contextually sensitive and therefore more relevant to clinical practice than an 'abstract' philosophical analysis. Bioethics has (arguably) always been an interdisciplinary field, and the rise of 'empirical' (bio)ethics need not be seen as an attempt to give a new name to the longstanding practice of interdisciplinary collaboration, but can perhaps best be understood as a substantive attempt to engage with the nature of that interdisciplinarity and to articulate the relationship between the many different disciplines (some of them empirical) that contribute to the field. It can also be described as an endeavour to explain how different disciplinary approaches can be integrated to effectively answer normative questions in bioethics, and fundamental to that endeavour is the need to think about how a robust methodology can be articulated that successfully marries apparently divergent epistemological and metaethical perspectives with method. This paper proposes 'Reflexive Bioethics' (RB) as a methodology for interdisciplinary and empirical bioethics, which utilizes a method of 'Reflexive Balancing' (RBL). RBL has been developed in response to criticisms of various forms of reflective equilibrium, and is built upon a pragmatic characterization of Bioethics and a 'quasi-moral foundationalism', which allows RBL to avoid some of the difficulties associated with RE and yet retain the flexible egalitarianism that makes it intuitively appealing to many. PMID:23444909

  12. Development of the Stretch Reflex in the Newborn: Reciprocal Excitation and Reflex Irradiation.

    ERIC Educational Resources Information Center

    Myklebust, Barbara M.; Gottlieb, Gerald L.

    1993-01-01

    When tendon jerk reflexes were tested in seven newborns from one- to three-days old, stretch reflex responses in all major muscle groups of the lower limb were elicited. This "irradiation of reflexes" is a normal phenomenon in newborns, with the pathway becoming suppressed during normal maturation. In individuals with cerebral palsy, however, the…

  13. The Anion Paradox in Sodium Taste Reception: Resolution by Voltage-Clamp Studies

    NASA Astrophysics Data System (ADS)

    Ye, Qing; Heck, Gerard L.; Desimone, John A.

    1991-11-01

    Sodium salts are potent taste stimuli, but their effectiveness is markedly dependent on the anion, with chloride yielding the greatest response. The cellular mechanisms that mediate this phenomenon are not known. This "anion paradox" has been resolved by considering the field potential that is generated by restricted electrodiffusion of the anion through paracellular shunts between taste-bud cells. Neural responses to sodium chloride, sodium acetate, and sodium gluconate were studied while the field potential was voltage-clamped. Clamping at electronegative values eliminated the anion effect, whereas clamping at electropositive potentials exaggerated it. Thus, field potentials across the lingual epithelium modulate taste reception, indicating that the functional unit of taste reception includes the taste cell and its paracellular microenvironment.

  14. Pyramidal tract neurons receptive to different forelimb joints act differently during locomotion

    PubMed Central

    Stout, Erik E.

    2012-01-01

    During locomotion, motor cortical neurons projecting to the pyramidal tract (PTNs) discharge in close relation to strides. How their discharges vary based on the part of the body they influence is not well understood. We addressed this question with regard to joints of the forelimb in the cat. During simple and ladder locomotion, we compared the activity of four groups of PTNs with somatosensory receptive fields involving different forelimb joints: 1) 45 PTNs receptive to movements of shoulder, 2) 30 PTNs receptive to movements of elbow, 3) 40 PTNs receptive to movements of wrist, and 4) 30 nonresponsive PTNs. In the motor cortex, a relationship exists between the location of the source of afferent input and the target for motor output. On the basis of this relationship, we inferred the forelimb joint that a PTN influences from its somatosensory receptive field. We found that different PTNs tended to discharge differently during locomotion. During simple locomotion shoulder-related PTNs were most active during late stance/early swing, and upon transition from simple to ladder locomotion they often increased activity and stride-related modulation while reducing discharge duration. Elbow-related PTNs were most active during late swing/early stance and typically did not change activity, modulation, or discharge duration on the ladder. Wrist-related PTNs were most active during swing and upon transition to the ladder often decreased activity and increased modulation while reducing discharge duration. These data suggest that during locomotion the motor cortex uses distinct mechanisms to control the shoulder, elbow, and wrist. PMID:22236716

  15. Discerning lived spirituality: the reception of otherness.

    PubMed

    Walton, Martin Neal

    2013-06-01

    A previous article focused on an analysis of prominent conceptualizations of spirituality in health care. The encompassing character of those approaches was viewed as problematic because too little attention is paid to the distinctiveness and particularities of spiritual experience. This article argues that the criteria gleaned from the prior analysis provide an impetus for a constructive discernment proposal of lived spirituality. The experience of otherness is provides a central clue to an understanding of spirituality particularly by two key terms, receptivity and transformation, as central characterizations of lived spirituality. These terms are investigated as they embrace operational potential for chaplaincy care. The article concludes with a reflection on chaplaincy care as it relates to spiritual practice. PMID:24040742

  16. The reception of relativity in China.

    PubMed

    Hu, Danian

    2007-09-01

    Having introduced the theory of relativity from Japan, the Chinese quickly and enthusiastically embraced it during the May Fourth Movement, virtually without controversy. This unique passion for and openness to relativity, which helped advance the study of theoretical physics in China in the 1930s, was gradually replaced by imported Soviet criticism after 1949. During the Cultural Revolution, radical Chinese ideologues sponsored organized campaigns against Einstein and relativity, inflicting serious damage on Chinese science and scientific education. China's economic reforms in the late 1970s empowered scientists and presented them with the opportunity to rehabilitate Einstein and call for social democracy. Einstein has since become the symbol in China of the unity of science and democracy, the two eminent objectives of the May Fourth Movement that remain to be achieved in full. Using the reception of relativity as a case study, the essay also discusses issues involving the historical study of modern Chinese science.

  17. The reception of relativity in China.

    PubMed

    Hu, Danian

    2007-09-01

    Having introduced the theory of relativity from Japan, the Chinese quickly and enthusiastically embraced it during the May Fourth Movement, virtually without controversy. This unique passion for and openness to relativity, which helped advance the study of theoretical physics in China in the 1930s, was gradually replaced by imported Soviet criticism after 1949. During the Cultural Revolution, radical Chinese ideologues sponsored organized campaigns against Einstein and relativity, inflicting serious damage on Chinese science and scientific education. China's economic reforms in the late 1970s empowered scientists and presented them with the opportunity to rehabilitate Einstein and call for social democracy. Einstein has since become the symbol in China of the unity of science and democracy, the two eminent objectives of the May Fourth Movement that remain to be achieved in full. Using the reception of relativity as a case study, the essay also discusses issues involving the historical study of modern Chinese science. PMID:17970426

  18. Developmental Stages in Receptive Grammar Acquisition: A Processability Theory Account

    ERIC Educational Resources Information Center

    Buyl, Aafke; Housen, Alex

    2015-01-01

    This study takes a new look at the topic of developmental stages in the second language (L2) acquisition of morphosyntax by analysing receptive learner data, a language mode that has hitherto received very little attention within this strand of research (for a recent and rare study, see Spinner, 2013). Looking at both the receptive and productive…

  19. The Comparative Reception of Darwinism: A Brief History

    ERIC Educational Resources Information Center

    Glick, Thomas F.

    2010-01-01

    The subfield of Darwin studies devoted to comparative reception coalesced around 1971 with the planning of a conference on the subject, at the University of Texas at Austin held in April 1972. The original focus was western Europe, Russia and the United States. Subsequently a spate of studies on the Italian reception added to the Eurocentric…

  20. Teacher Receptivity to System-Wide Educational Change.

    ERIC Educational Resources Information Center

    Moroz, Rose; Waugh, Russell F.

    2000-01-01

    Examines Western Australian high-school teachers' receptivity to a systemwide educational change, the use of (mandated) student-outcome statements. Teachers' receptivity is related to their beliefs about the change and to their attitudes and beliefs about its nonmonetary cost benefits, significant- other support, and comparison with the previous…

  1. Cross-National Policy Borrowing: Understanding Reception and Translation

    ERIC Educational Resources Information Center

    Steiner-Khamsi, Gita

    2014-01-01

    The article examines two key concepts in research on policy borrowing and lending that are often used to explain why and how educational reforms travel across national boundaries: reception and translation. The studies on reception analyse the political, economic, and cultural reasons that account for the attractiveness of a reform from elsewhere.…

  2. Reflexive Practice: To Enhance Student Learning

    ERIC Educational Resources Information Center

    Roebuck, Joanne

    2007-01-01

    This paper reports on the use of reflexive practice activities designed to enhance learning for first year law students at James Cook University, Australia. The paper considers various aspects of student learning and explores connections between reflexive practice and concepts such as deep learning, understanding, motivation and engagement, and…

  3. [Non-reflex activity of the CNS].

    PubMed

    Brozek, G

    1995-06-01

    Recent studies of biological rhythms have modified Sherrington's concept of nervous system as exclusively reflexive to include the fact that some neural activity is also endogenously rhythmic. Reflexes are undoubtedly the most important components of animal's and human behavior. But are reflexes the basic units of all complex movements and acts? Rhythmical movements such as respiration, walking and running and other forms of locomotion, as well as rhythmical alimentary processes such as respiration, walking and running and other forms of locomotion, as well as rhythmical alimentary processes such as licking, mastication, and the peristaltic propulsion of nutrients and waste are examples of acts controlled by intrinsic oscillators, so called central pattern generators. Information from the periphery is, however, essential for controlling the extent and rate of movements. Between reflex and non-reflex activity it is possible to place complex species-specific responses called by ethologists fixed-action patterns. Recent investigators have shown that many complex sequences of behavior like speech or piano playing are determined by an internal plan, rather than being generated by a "chain" of reflexes. Non-reflexive activity appears earlier in ontogeny, and is probably phylogenetically older than reflexes.

  4. Are H-reflex and M-wave recruitment curve parameters related to aerobic capacity?

    PubMed

    Piscione, Julien; Grosset, Jean-François; Gamet, Didier; Pérot, Chantal

    2012-10-01

    Soleus Hoffmann reflex (H-reflex) amplitude is affected by a training period and type and level of training are also well known to modify aerobic capacities. Previously, paired changes in H-reflex and aerobic capacity have been evidenced after endurance training. The aim of this study was to investigate possible links between H- and M-recruitment curve parameters and aerobic capacity collected on a cohort of subjects (56 young men) that were not involved in regular physical training. Maximal H-reflex normalized with respect to maximal M-wave (H(max)/M(max)) was measured as well as other parameters of the H- or M-recruitment curves that provide information about the reflex or direct excitability of the motoneuron pool, such as thresholds of stimulus intensity to obtain H or M response (H(th) and M(th)), the ascending slope of H-reflex, or M-wave recruitment curves (H(slp) and M(slp)) and their ratio (H(slp)/M(slp)). Aerobic capacity, i.e., maximal oxygen consumption and maximal aerobic power (MAP) were, respectively, estimated from a running field test and from an incremental test on a cycle ergometer. Maximal oxygen consumption was only correlated with M(slp), an indicator of muscle fiber heterogeneity (p < 0.05), whereas MAP was not correlated with any of the tested parameters (p > 0.05). Although higher H-reflex are often described for subjects with a high aerobic capacity because of endurance training, at a basic level (i.e., without training period context) no correlation was observed between maximal H-reflex and aerobic capacity. Thus, none of the H-reflex or M-wave recruitment curve parameters, except M(slp), was related to the aerobic capacity of young, untrained male subjects.

  5. Toward a critical ethical reflexivity: phenomenology and language in Maurice Merleau-Ponty.

    PubMed

    Murray, Stuart J; Holmes, Dave

    2013-07-01

    Working within the tradition of continental philosophy, this article argues in favour of a phenomenological understanding of language as a crucial component of bioethical inquiry. The authors challenge the 'commonsense' view of language, in which thinking appears as prior to speaking, and speech the straightforward vehicle of pre-existing thoughts. Drawing on Maurice Merleau-Ponty's (1908-1961) phenomenology of language, the authors claim that thinking takes place in and through the spoken word, in and through embodied language. This view resituates bioethics as a matter of bodies that speak. It also refigures the meaning of ethical self-reflexion, and in so doing offers an alternative view on reflexivity and critique. Referring to the Kantian critical tradition and its reception by Hannah Arendt and Michel Foucault, we advance a position we call 'critical ethical reflexivity'. We contend that Merleau-Ponty's phenomenology of language offers valuable insight into ethical reflexivity and subject formation. Moreover, his understanding of language may foster new qualitative empirical research in bioethics, lead to more nuanced methods for interpreting personal narratives, and promote critical self-reflexion as necessary for bioethical inquiry.

  6. Toward a critical ethical reflexivity: phenomenology and language in Maurice Merleau-Ponty.

    PubMed

    Murray, Stuart J; Holmes, Dave

    2013-07-01

    Working within the tradition of continental philosophy, this article argues in favour of a phenomenological understanding of language as a crucial component of bioethical inquiry. The authors challenge the 'commonsense' view of language, in which thinking appears as prior to speaking, and speech the straightforward vehicle of pre-existing thoughts. Drawing on Maurice Merleau-Ponty's (1908-1961) phenomenology of language, the authors claim that thinking takes place in and through the spoken word, in and through embodied language. This view resituates bioethics as a matter of bodies that speak. It also refigures the meaning of ethical self-reflexion, and in so doing offers an alternative view on reflexivity and critique. Referring to the Kantian critical tradition and its reception by Hannah Arendt and Michel Foucault, we advance a position we call 'critical ethical reflexivity'. We contend that Merleau-Ponty's phenomenology of language offers valuable insight into ethical reflexivity and subject formation. Moreover, his understanding of language may foster new qualitative empirical research in bioethics, lead to more nuanced methods for interpreting personal narratives, and promote critical self-reflexion as necessary for bioethical inquiry. PMID:23718744

  7. The tripartite origins of the tonic neck reflex: Gesell, Gerstmann, and Magnus.

    PubMed

    Shevell, Michael

    2009-03-01

    The standard neurologic examination of the newborn and infant includes the elicitation of the tonic neck reflex. Normally present, its persistence is suggestive of neurologic dysfunction and a prognostic marker highly suggestive of an adverse outcome. Working in different fields, with different approaches and largely independently, three leaders of early 20th century neurosciences (Rudolf Magnus, Josef Gerstmann, and Arnold Gesell) elaborated different aspects of this primitive reflex. Magnus provided the first description in an animal model utilizing a meticulously prepared decerebrate cat correctly identifying the reflex's reliance on proprioceptors in the neck and processing in the upper cervical segment. Gerstmann first described its occurrence in the setting of neurologic disease, providing a meticulous written description in an early description of the index case of what would later be eponymously designated Gerstmann-Straussler-Scheinker syndrome. Gesell initially described the reflex's fundamental occurrence in normal young infants, highlighting its adaptive role in early development and its persistence as a hallmark of neurologic pathology.

  8. Distributed acoustic receptivity in laminar flow control configurations

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan

    1992-01-01

    A model problem related to distributed receptivity to free-stream acoustic waves in laminar flow control (LFC) configurations is studied, within the Orr-Sommerfield framework, by a suitable extension of the Goldstein-Ruban theory for receptivity due to localized disturbances on the airfoil surface. The results, thus, complement the earlier work on the receptivity produced by local variations in the surface suction and/or surface admittance. In particular, we show that the cumulative effect of the distributed receptivity can be substantially larger than that of a single, isolated suction strip or slot. Furthermore, even if the receptivity is spread out over very large distances, the most effective contributions come from a relatively short region in vicinity of the lower branch of the neutral stability curve. The length scale of this region is intermediate to that of the mean of these two length scales. Finally, it is found that the receptivity is effectively dominated by a narrow band of Fourier components from the wall-suction and admittance distributions, roughly corresponding to a detuning of less than ten percent with respect to the neutral instability wavenumber at the frequency under consideration. The results suggest that the drop-off in receptivity magnitudes away from the resonant wavenumber is nearly independent of the frequency parameter.

  9. Quantum security in homodyne reception using weak coherent states

    NASA Astrophysics Data System (ADS)

    García, E.; López, J. A.; Mendieta, F. J.; Arvizu, A.

    2011-09-01

    We present an experimental 8-port Balanced Homodyne Detector at 1550 nm wavelength, operating in free space, implemented with polarization devices to produce a circularly polarized local oscillator, splitting its In-Phase and Quadrature components to beat separately with the weak coherent incoming signal. This allows the simultaneous measurements of the 2 quadratures at the price of an additional noise due to the vacuum fields that leak via the unused ports, resulting in a modified Husimi function for joint probability distribution for the quadrature components. These schemes require the proper optical phase synchronization between the local oscillator and the incoming field, which constitutes a challenge for weak coherent state reception. To achieve this we designed and implemented an optical Costas loop; the feedback loop (especially the loop filter) which is a result of the optimal design has an impact on the mutual information between transmitter and receiver, being this parameter a condition to generate the cryptographic key. We present experimental and theoretical results on the performance of the mutual information between the transmitter and the receiver due the phase error for different photon numbers.

  10. Cutaneous reflex modulation and self-induced reflex attenuation in cerebellar patients.

    PubMed

    Hoogkamer, Wouter; Van Calenbergh, Frank; Swinnen, Stephan P; Duysens, Jacques

    2015-02-01

    Modulation of cutaneous reflexes is important in the neural control of walking, yet knowledge about underlying neural pathways is still incomplete. Recent studies have suggested that the cerebellum is involved. Here we evaluated the possible roles of the cerebellum in cutaneous reflex modulation and in attenuation of self-induced reflexes. First we checked whether leg muscle activity during walking was similar in patients with focal cerebellar lesions and in healthy control subjects. We then recorded cutaneous reflex activity in leg muscles during walking. Additionally, we compared reflexes after standard (computer triggered) stimuli with reflexes after self-induced stimuli for both groups. Biceps femoris and gastrocnemius medialis muscle activity was increased in the patient group compared with the control subjects, suggesting a coactivation strategy to reduce instability of gait. Cutaneous reflex modulation was similar between healthy control subjects and cerebellar patients, but the latter appeared less able to attenuate reflexes to self-induced stimuli. This suggests that the cerebellum is not primarily involved in cutaneous reflex modulation but that it could act in attenuation of self-induced reflex responses. The latter role in locomotion would be consistent with the common view that the cerebellum predicts sensory consequences of movement.

  11. Achilles tendon reflex measuring system

    NASA Astrophysics Data System (ADS)

    Szebeszczyk, Janina; Straszecka, Joanna

    1995-06-01

    The examination of Achilles tendon reflex is widely used as a simple, noninvasive clinical test in diagnosis and pharmacological therapy monitoring in such diseases as: hypothyroidism, hyperthyroidism, diabetic neuropathy, the lower limbs obstructive angiopathies and intermittent claudication. Presented Achilles tendon reflect measuring system is based on the piezoresistive sensor connected with the cylinder-piston system. To determinate the moment of Achilles tendon stimulation a detecting circuit was used. The outputs of the measuring system are connected to the PC-based data acquisition board. Experimental results showed that the measurement accuracy and repeatability is good enough for diagnostics and therapy monitoring purposes. A user friendly, easy-to-operate measurement system fulfills all the requirements related to recording, presentation and storing of the patients' reflexograms.

  12. Numerical Studies of Boundary-Layer Receptivity

    NASA Technical Reports Server (NTRS)

    Reed, Helen L.

    1995-01-01

    Direct numerical simulations (DNS) of the acoustic receptivity process on a semi-infinite flat plate with a modified-super-elliptic (MSE) leading edge are performed. The incompressible Navier-Stokes equations are solved in stream-function/vorticity form in a general curvilinear coordinate system. The steady basic-state solution is found by solving the governing equations using an alternating direction implicit (ADI) procedure which takes advantage of the parallelism present in line-splitting techniques. Time-harmonic oscillations of the farfield velocity are applied as unsteady boundary conditions to the unsteady disturbance equations. An efficient time-harmonic scheme is used to produce the disturbance solutions. Buffer-zone techniques have been applied to eliminate wave reflection from the outflow boundary. The spatial evolution of Tollmien-Schlichting (T-S) waves is analyzed and compared with experiment and theory. The effects of nose-radius, frequency, Reynolds number, angle of attack, and amplitude of the acoustic wave are investigated. This work is being performed in conjunction with the experiments at the Arizona State University Unsteady Wind Tunnel under the direction of Professor William Saric. The simulations are of the same configuration and parameters used in the wind-tunnel experiments.

  13. Receptive females mitigate costs of sexual conflict.

    PubMed

    Harano, T

    2015-02-01

    Males typically gain fitness from multiple mating, whereas females often lose fitness from numerous mating, potentially leading to sexual conflict over mating. This conflict is expected to favour the evolution of female resistance to mating. However, females may incur male harassment if they refuse to copulate; thus, greater female resistance may increase costs imposed by males. Here, I show that the evolution of resistance to mating raises fitness disadvantages of interacting with males when mating is harmful in female adzuki bean beetles, Callosobruchus chinensis. Females that were artificially selected for higher and lower remating propensity evolved to accept and resist remating, respectively. Compared with females that evolved to accept remating, females that evolved to resist it suffered higher fitness costs from continuous exposure to males. The costs of a single mating measured by the effect on longevity did not differ among selection line females. This study indicates that receptive rather than resistant females mitigate the fitness loss resulting from sexual conflict, suggesting that even though mating is harmful, females can evolve to accept additional mating.

  14. Paper and people: the work of the casualty reception clerk.

    PubMed

    Hughes, D

    1989-12-01

    This paper examines the exercise of discretion by casualty reception staff, focussing on the problems of accountability that arise when their judgements help shape the process of patient categorization that culminates in clinical diagnosis. Rules and guidelines which ostensibly relate to bureaucratic objectives, are applied in ways which reflect situational exigencies of reception work, and values embedded in organisational culture. But reception staff are reluctant to acknowledge the importance of their decisions, and, particularly where judgements relate to patient condition, present rule-use as a straightforward and certain activity in which interpretation plays little part. PMID:10304220

  15. [Urinary urgency and reflex incontinence].

    PubMed

    Madersbacher, H

    1991-07-01

    Urge and reflex incontinence are caused by detrusor dysfunction:urgency may be due to hyperactivity or hypersensitivity of the bladder. Neurogenic hyperactivity of the detrusor is called detrusor hyperreflexia: the neurogenic uninhibited bladder is caused by incomplete, and the so-called reflex bladder by complete, suprasacral lesions. The pathophysiology of symptomatic and idiopathic detrusor hyperactivity and the therapeutic armentarium are described. Bladder drill together with biofeedback and pharmacotherapy with spasmolytic drugs - several potent spasmolytic drugs with different modes of action are available - are the basis of treatment for hyperactivity and hypersensitivity of the detrusor. An alternative is electrostimulation: stimulation of the afferents of the pudendal nerve, via the pelvic floor (anal, vaginal), percutaneously (dorsal nerve of the penis, clitoric nerve) or by the implantation of electrodes results in inhibition of the detrusor. Most (80-90%) patients can be treated successfully by conservative means. Operative measurements comprise bladder denervation and bladder augmentation. The results of bladder denervation by transtrigonal phenolization of the pelvic plexus are highly controversial. In patients with uncontrollable hyperactivity of the detrusor, augmentation of the bladder (e.g. clam ileocystoplasty) is the method of choice, while for those with uncontrollable hypersensitivity of the detrusor, cystectomy followed by bladder substitution should be performed as a last resort. Treatment for urinary incontinence due to detrusor hyperreflexia must be selected bearing in mind that bladder emptying is inadequate, in most cases because of dyssynergia between detrusor and external sphincter. Therapy is basically aimed at transforming hyperreflexia of the detrusor into hyporeflexia, primarily by potent spasmolytic drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. The Pupillary Light Reflex in Idiopathic Intracranial Hypertension

    PubMed Central

    Park, Jason C.; Moss, Heather E.; McAnany, J. Jason

    2016-01-01

    Purpose To evaluate the effects of idiopathic intracranial hypertension (IIH) on rod-, cone-, and melanopsin-mediated pupillary light reflexes (PLRs). Methods Pupillary light reflexes elicited by full-field, brief-flash stimuli were recorded in 13 IIH patients and 13 normal controls. Subjects were dark-adapted for 10 minutes and the PLR was recorded in response to short-wavelength flashes (0.001 cd/m2: rod condition; 450 cd/m2: melanopsin condition). Subjects were then exposed to a rod-suppressing field and 10 cd/m2 long-wavelength flashes were presented (cone condition). Pupillary light reflexes were quantified as the maximum transient constriction (rod and cone conditions) and the post-illumination pupil constriction (melanopsin condition), relative to the baseline pupil size. Diagnostic power was evaluated using receiver operating characteristic (ROC) analysis. Results The IIH patients had significantly smaller PLRs under the melanopsin (P < 0.001) and rod (P = 0.04) paradigms; a trend for reduced cone-mediated PLRs was also found (P = 0.08). Receiver operating characteristic analysis indicated areas under the curves (AUC) of 0.83 (melanopsin-meditated; P = 0.001), 0.71 (rod-mediated; P = 0.07), and 0.77 (cone-mediated; P = 0.02). The AUC (0.90, P < 0.001), sensitivity (85%), and specificity (85%) were high for ROC analysis performed on the mean of the rod, cone, and melanopsin PLRs. Conclusions Pupillary light reflex reductions in IIH patients indicate compromised RGC function. PLR measurement, particularly under rod- and melanopsin-mediated conditions, may be a useful adjunct to standard clinical measures of visual function in IIH. PMID:26746015

  17. Astronomical Data Reduction Workflows with Reflex

    NASA Astrophysics Data System (ADS)

    Ballester, P.; Bramich, D.; Forchi, V.; Freudling, W.; Garcia-Dabó, C. E.; klein Gebbinck, M.; Modigliani, A.; Moehler, S.; Romaniello, M.

    2014-05-01

    Reflex (http://www.eso.org/reflex) is an environment that provides an easy and flexible way to reduce VLT/VLTI science data using the ESO. Its top-level functionalities are: (1) Reflex allows to graphically specify the sequence in which the data reduction steps are executed, including conditional stops, loops and conditional branches, (2) Reflex makes it easy to inspect the intermediate and final data products and to repeat selected processing steps to optimize the data reduction, (3) the data organization necessary to reduce the data is built into the system and is fully automatic, (4) advanced users can plug-in their own Python or IDL modules and steps into the data reduction sequence, and (5) Reflex supports the development of data reduction workflows based on the ESO Common Pipeline Library. Reflex is based on the concept of a scientific workflow, whereby the data reduction cascade is rendered graphically and data seamlessly flow from one processing step to the next. It is distributed with a number of complete test datasets so that users can immediately start experimenting and familiarize themselves with the system (http://www.eso.org/pipelines). In this demo, we present the latest version of Reflex and its applications for astronomical data reduction processes.

  18. The Reflexes of the Fundus Oculi

    PubMed Central

    Ballantyne, A. J.

    1940-01-01

    The fundus reflexes reveal, in a manner not yet completely understood, the texture and contour of the reflecting surfaces and the condition of the underlying tissues. In this way they may play an important part in the biomicroscopy of the eye. The physiological reflexes are seen at their best in the eyes of young subjects, in well-pigmented eyes, with undilated pupils and with emmetropic refraction. Their absence during the first two decades, or their presence after the forties, their occurrence in one eye only, their appearance, disappearance or change of character should suggest the possibility of some pathological state. The investigation and interpretation of the reflexes are notably assisted by comparing the appearances seen with long and short wave lights such as those of the sodium and mercury vapour lamps, in addition to the usual ophthalmoscopic lights. Most of the surface reflexes disappear in the light of the sodium lamp, sometimes revealing important changes in the deeper layers of the retina and choroid. The physiological reflexes, chiefly formed on the surface of the internal limiting membrane, take the forms of the familiar watered silk or patchy reflexes, the peri-macular halo, the fan reflex in the macular depression and the reflex from the foveal pit. The watered silk or patchy reflexes often show a delicate striation which follows the pattern of the nerve-fibre layer, or there may be a granular or criss-cross texture. Reflexes which entirely lack these indications of “texture” should be considered as possibly pathological. This applies to the “beaten metal” reflexes and to those formed on the so-called hyaloid membrane. The occurrence of physiological reflexes in linear form is doubtful, and the only admittedly physiological punctate reflexes are the so-called Gunn's dots. Surface reflexes which are broken up into small points or flakes are pathological, and are most frequently seen in the central area of the fundus in cases of pigmentary

  19. [Research progress of rectoanal inhibitory reflex].

    PubMed

    Yin, Shuhui; Zhao, Ke

    2015-12-01

    The understanding of rectoanal inhibitory reflex (RAIR) is progressing for the latest 100 years. From the discovery of its important role in diagnosis of Hirschsprung's disease to all aspects of its development, reflex pathways, neural regulation and physiological functions, there have been more in-depth explorations. It is now recognized that a number of other diseases also have a more specific performance of RAIR. It has become an important and indispensable part to anorectal manometry. Research progress of rectoanal inhibitory reflex is reviewed in this article.

  20. Changes in the Achilles tendon reflexes following Skylab missions

    NASA Technical Reports Server (NTRS)

    Baker, J. T.; Nicogossian, A. E.; Hoffler, G. W.; Johnson, R. L.; Hordinsky, J. R.

    1977-01-01

    Postflight measurements of Achilles tendon reflex duration on Skylab crewmen indicate a state of disequilibrium between the flexor and extensor muscle groups with an initial decrease in reflex duration. As the muscles regain strength and mass there occurs an overcompensation reflected by increased reflex duration. Finally, when a normal neuromuscular state is reached the reflex duration returns to baseline value.

  1. Low oral receptivity for dengue type 2 viruses of Aedes albopictus from Southeast Asia compared with that of Aedes aegypti.

    PubMed

    Vazeille, Marie; Rosen, Leon; Mousson, Laurence; Failloux, Anna-Bella

    2003-02-01

    Dengue hemorrhagic fever has been a major health problem in Asia since the 1950s. During this period, the former principal vector of dengue viruses in Asia, Aedes albopictus, was replaced by Aedes aegypti in most major cities of the area. Ae. aegypti is now considered the main vector of dengue viruses in Asia. Surprisingly, however, this mosquito has been described as having a relatively low oral receptivity for dengue viruses compared with Ae. albopictus. In the present study, we compared the relative oral receptivities of Ae. aegypti and Ae. albopictus collected in southeast Asia from both sympatric and allopatric breeding sites. In all instances, the oral receptivity of Ae. aegypti to the dengue type 2 virus used was significantly higher than that of Ae. albopictus. We also compared the relative oral receptivity of Ae. aegypti and Ae. albopictus for two other low-passage strains of dengue 2. In all instances, Ae. aegypti was significantly more receptive than Ae. albopictus. It should be noted, however, that the difference was found only for Ae. albopictus recently collected from the field (Ta Promh strain, Cambodia, 2001) and not for an Ae. albopictus strain that had been colonized for many years (Oahu strain, Hawaii, 1971). We also observed a significant increase in the infection rate of Ae. albopictus of the Ta Promh strain with increasing generations in the laboratory. These observations demonstrate the importance of considering the colonization history of mosquitoes when assessing their susceptibility to infection with dengue viruses and, perhaps, other arboviruses.

  2. "IN ALL ITS HIDEOUS AND APPALLING NAKEDNESS AND TRUTH": THE RECEPTION OF SOME ANATOMICAL COLLECTIONS IN GEORGIAN AND VICTORIAN ENGLAND.

    PubMed

    Talairach-Vielmas, Laurence

    2015-01-01

    This article explores the reception of some anatomical collections in Georgian and Victorian England. Both private medical museums and public anatomical museums reflected the central role played by anatomy in medical knowledge and education in the eighteenth and nineteenth centuries. However, because they were associated with death and sexuality, anatomical museums were both products of enlightenment science and potentially immoral loci likely to corrupt young and innocent women. But, as this article shows, the reasons behind the hostile receptions of some collections varied throughout the centuries, revealing in so doing the gradual professionalization of the medical field and growing monopoly of medical professionals over medical knowledge.

  3. Interior view, anteroom of the postmaster general's reception hall; shown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view, anteroom of the postmaster general's reception hall; shown here are two of the six aluminum statues of postal delivery men - New Post Office Building, Twelfth Street and Pennsylvania Avenue, Washington, District of Columbia, DC

  4. Reception of longitudinal vector potential radiation with a plasma antenna

    SciTech Connect

    Zimmerman, Robert K. Jr.

    2013-07-28

    To help resolve the long-running debate between physicists and engineers regarding the existence of the magnetic vector potential, herewith we describe an experiment demonstrating reception of time-harmonic vector potential radiation at 1.3 GHz.

  5. 45. Everett, Weinreb, photographer DETAIL, CEMENT TILE PATTERN FROM RECEPTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    45. Everett, Weinreb, photographer DETAIL, CEMENT TILE PATTERN FROM RECEPTION HALL LOOKING EAST ACROSS ARRIVAL LOBBY FLOOR - Los Angeles Union Passenger Terminal, Tracks & Shed, 800 North Alameda Street, Los Angeles, Los Angeles County, CA

  6. Views of the Apollo 11 Twentieth Anniversary Black Tie reception

    NASA Technical Reports Server (NTRS)

    1989-01-01

    View from the Apollo 11 Twentieth Anniversary Black Tie reception at the downtown Houston Hyatt Regency Hotel. Scene show NASA/JSC Director Aaron Cohen talking with NASA Administrator Richard H. Truly and his wife, Cody.

  7. 115. INTERIOR, SIXTH FLOOR, WING 6100 WEST, SUITE 6000, RECEPTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    115. INTERIOR, SIXTH FLOOR, WING 6100 WEST, SUITE 6000, RECEPTION AREA, DETAIL OF GRAINED RADIATOR CABINET - U.S. Department of the Interior, Eighteenth & C Streets Northwest, Washington, District of Columbia, DC

  8. 12. INTERIOR, SHOWING PART OF RECEPTION ROOM IN CENTER SECTION. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. INTERIOR, SHOWING PART OF RECEPTION ROOM IN CENTER SECTION. VIEW TO SOUTHEAST. - Fort David A. Russell, Red Cross Building, Third Street between Randall Avenue & Tenth Cavalry Avenue, Cheyenne, Laramie County, WY

  9. 10. INTERIOR, SHOWING RECEPTION ROOM IN CENTER SECTION, WITH MAIN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. INTERIOR, SHOWING RECEPTION ROOM IN CENTER SECTION, WITH MAIN ENTRANCE AT RIGHT. VIEW TO SOUTHWEST. - Fort David A. Russell, Red Cross Building, Third Street between Randall Avenue & Tenth Cavalry Avenue, Cheyenne, Laramie County, WY

  10. Uterine Receptivity to Human Embryonic Implantation: Histology, Biomarkers, and Transcriptomics

    PubMed Central

    Aghajanova, L; Hamilton, AE; Giudice, LC

    2008-01-01

    Embryonic implantation is a dynamic process of paracrine interactions between the maternal compartment and the conceptus and involves a receptive endometrium and a developmentally competent blastocyst. Herein, we review histology, clinical approaches, and the promise of transcriptomics in elucidating mechanisms underlying implantation and development of biomarkers of uterine receptivity - with an eye to diagnose and treat implantation-based disorders of miscarriage, fetal growth restriction, pre-eclampsia, and infertility. PMID:18035563

  11. Support for non-locking parallel reception of packets belonging to a single memory reception FIFO

    DOEpatents

    Chen, Dong; Heidelberger, Philip; Salapura, Valentina; Senger, Robert M.; Steinmacher-Burow, Burkhard; Sugawara, Yutaka

    2011-01-27

    A method and apparatus for distributed parallel messaging in a parallel computing system. A plurality of DMA engine units are configured in a multiprocessor system to operate in parallel, one DMA engine unit for transferring a current packet received at a network reception queue to a memory location in a memory FIFO (rmFIFO) region of a memory. A control unit implements logic to determine whether any prior received packet destined for that rmFIFO is still in a process of being stored in the associated memory by another DMA engine unit of the plurality, and prevent the one DMA engine unit from indicating completion of storing the current received packet in the reception memory FIFO (rmFIFO) until all prior received packets destined for that rmFIFO are completely stored by the other DMA engine units. Thus, there is provided non-locking support so that multiple packets destined for a single rmFIFO are transferred and stored in parallel to predetermined locations in a memory.

  12. Numerical Simulation of Receptivity for a Transition Experiment

    NASA Technical Reports Server (NTRS)

    Collis, S. Scott; Joslin, R. D. (Technical Monitor)

    2000-01-01

    The cost of fuel to overcome turbulence induced viscous drag on a commercial airplane constitutes a significant fraction of the operating cost of an airline. Achieving laminar flow and maintaining it over a large portion of the wing can significantly reduce the viscous drag, and hence the cost. Design of such laminar-flow-control wings and their practical operation requires the ability to accurately and reliably predict the transition from laminar to turbulent flow. The transition process begins with the conversion of environmental and surface disturbances into the instability waves of the flow by a process called receptivity. The goal of the current research project has been to improve the prediction of transition through a better understanding of the physics of receptivity. The initial objective of this work was to investigate the specific stability and receptivity characteristics of a particular experimental investigation of boundary layer receptivity at NASA Langley. Some simulation results using direct solutions of the linearized Navier-Stokes equations which modeled this experiment where presented in the 1999 APS DFD meeting. However, based on these initial investigations, it became clear that to cover the vast receptivity parameter space required for a practical transition prediction tool, more efficient methods would be required. Thus, the focus of this research was shifted from modeling this particular experiment to formulating and developing new techniques that could efficiently yet accurately predict receptivity for a wide range of disturbance conditions.

  13. The legacy of care as reflexive learning

    PubMed Central

    García, Marta Rodríguez; Moya, Jose Luis Medina

    2016-01-01

    Abstract Objective: to analyze whether the tutor's use of reflexive strategies encourages the students to reflect. The goal is to discover what type of strategies can help to achieve this and how tutors and students behave in the practical context. Method: a qualitative and ethnographic focus was adopted. Twenty-seven students and 15 tutors from three health centers participated. The latter had received specific training on reflexive clinical tutoring. The analysis was developed through constant comparisons of the categories. Results: the results demonstrate that the tutors' use of reflexive strategies such as didactic questioning, didactic empathy and pedagogical silence contributes to encourage the students' reflection and significant learning. Conclusions: reflexive practice is key to tutors' training and students' learning. PMID:27305180

  14. Hamstrings stretch reflex in human spasticity

    PubMed Central

    Burke, David; Gillies, J. D.; Lance, James W.

    1971-01-01

    In 16 patients with spastic paralysis the hamstrings stretch reflex was found to increase as the velocity of stretch increased, and generally to subside after movement ceased. These effects are attributable to the dynamic property of the primary spindle ending. The stretch reflex commonly appeared in only the last third of the stretching movement and was maximal as the knee became fully extended. This is consistent with the static properties of the primary and secondary spindle endings, and accounts for the absence of the clasp-knife phenomenon in the spastic hamstrings. The difference in the nature of the stretch reflex in spastic flexor and extensor muscles is best explained by the differential reflex effects of group II afferent fibres which facilitate flexor motoneurones and inhibit extensor motoneurones. PMID:4255176

  15. Reflex sympathetic dystrophy following traumatic myelopathy.

    PubMed

    Wainapel, S F

    1984-04-01

    Two cases of reflex sympathetic dystrophy in the upper extremity of patients with traumatic cervical spinal cord injuries are reported. Both patients had very incomplete lesions with early neurological recovery, suggesting an underlying central cord syndrome. Although reflex sympathetic dystrophy is often seen following stroke, it has only rarely been documented in traumatic myelopathy, and it should be considered in the differential diagnosis of unexplained pain syndromes in the extremities of paraplegic or quadriplegic patients. PMID:6728500

  16. The pupillary light reflex in normal subjects.

    PubMed Central

    Ellis, C J

    1981-01-01

    In 19 normal subjects the pupillary reflex to light was studied over a range of stimulus intensities by infrared electronic pupillography and analysed by a computer technique. Increasing stimulus intensity was associated with an increase in direct light reflex amplitude and maximum rate of constriction and redilatation. Latency from stimulus to onset of response-decreased with increasing stimulus intensity. The normal range for each of these parameters is given and the significance of these results in clinical pupillary assessment discussed. PMID:7326222

  17. Compressibility effects on the non-linear receptivity of boundary layers to dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Denison, Marie F. C.

    The reduction of drag and aerodynamic heating caused by boundary layer transition is of central interest for the development of hypersonic vehicles. Receptivity to flow perturbation in the form of Tollmien-Schlichting (TS) wave growth often determines the first stage of the transition process, which can be delayed by depositing specific excitations into the boundary layer. Weakly ionized Dielectric Barrier Discharge (DBD) actuators are being investigated as possible sources of such excitations, but little is known today about their interaction with high-speed flows. In this framework, the first part of the thesis is dedicated to a receptivity study of laminar compressible boundary layers over a flat plate by linear stability analysis following an adjoint operator formulation, under DBD representative excitations assumed independent of flow conditions. The second part of the work concentrates on the development of a coupled plasma-Navier and Stokes solver targeted at the study of supersonic flow and compressibility effects on DBD forcing and non-parallel receptivity. The linear receptivity study of quasi-parallel compressible flows reveals several interesting features such as a significant shift of the region of maximum receptivity deeper into the flow at high Mach number and strong wave amplitude reduction compared to incompressible flows. The response to DBD relevant excitation distributions and to variations of the base flow conditions and system length scales follows these trends. Observed absolute amplitude changes and relative sensitivity modifications between source types are related to the evolution of the offset between forcing peak profile and relevant adjoint mode maximum. The analysis highlights the crucial importance of designing and placing the actuator in a way that matches its force field to the position of maximum boundary layer receptivity for the specific flow conditions of interest. In order to address the broad time and length scale spectrum

  18. [The oculocardiac reflex during vitrectomy under neuroleptanalgesia].

    PubMed

    Dornberger, I; Quast, D; Velhagen, K H; Bellach, J; Guckler, A

    1991-01-01

    Oculocardiac reflex (OCR) is a frequently occurring complication in eye operations. It is a trigemino-vagal reflex characterised by the clinical occurrence of bradycardia and other cardiac rhythm disturbances following manipulations on the eye and its surroundings especially after traction of the external eye muscles. In this paper based on an analysis of 402 anaesthesia records, a bradycardia frequency (f = less than 60/min) of 31.8% was noted while other rhythm disturbances occurred in 5.7%. Predisposition facts were identified as age over 50, hypertension and cardiac diseases requiring medication with cardiac drugs. The frequency of OCR is considerably lowered by diabetes mellitus. Examination of 159 traction measurements made at the lateral rectus muscle revealed that the first manipulation made at the rectus bulbi superior muscle resulted in a statistically significantly stronger reflex activity than at the other muscles. In a further series of investigations in which rectus bulbi superior muscle was tested last, this muscle again showed the biggest frequency deviation. Only determination of the percentage heart rate decrease is suitable for characterising reflex activity. The frequency of the reflex occurring in our study was 71.7%, the result being reduced by the high proportion of diabetics, who are relatively reflex insensitive.

  19. The Reflexes of the Fundus Oculi

    PubMed Central

    Ballantyne, A. J.

    1940-01-01

    The fundus reflexes reveal, in a manner not yet completely understood, the texture and contour of the reflecting surfaces and the condition of the underlying tissues. In this way they may play an important part in the biomicroscopy of the eye. The physiological reflexes are seen at their best in the eyes of young subjects, in well-pigmented eyes, with undilated pupils and with emmetropic refraction. Their absence during the first two decades, or their presence after the forties, their occurrence in one eye only, their appearance, disappearance or change of character should suggest the possibility of some pathological state. The investigation and interpretation of the reflexes are notably assisted by comparing the appearances seen with long and short wave lights such as those of the sodium and mercury vapour lamps, in addition to the usual ophthalmoscopic lights. Most of the surface reflexes disappear in the light of the sodium lamp, sometimes revealing important changes in the deeper layers of the retina and choroid. The physiological reflexes, chiefly formed on the surface of the internal limiting membrane, take the forms of the familiar watered silk or patchy reflexes, the peri-macular halo, the fan reflex in the macular depression and the reflex from the foveal pit. The watered silk or patchy reflexes often show a delicate striation which follows the pattern of the nerve-fibre layer, or there may be a granular or criss-cross texture. Reflexes which entirely lack these indications of “texture” should be considered as possibly pathological. This applies to the “beaten metal” reflexes and to those formed on the so-called hyaloid membrane. The occurrence of physiological reflexes in linear form is doubtful, and the only admittedly physiological punctate reflexes are the so-called Gunn's dots. Surface reflexes which are broken up into small points or flakes are pathological, and are most frequently seen in the central area of the fundus in cases of pigmentary

  20. Reflex ring laser amplifier system

    SciTech Connect

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  1. Whole-body vibration-induced muscular reflex: Is it a stretch-induced reflex?

    PubMed Central

    Cakar, Halil Ibrahim; Cidem, Muharrem; Sebik, Oguz; Yilmaz, Gizem; Karamehmetoglu, Safak Sahir; Kara, Sadik; Karacan, Ilhan; Türker, Kemal Sıtkı

    2015-01-01

    [Purpose] Whole-body vibration (WBV) can induce reflex responses in muscles. A number of studies have reported that the physiological mechanisms underlying this type of reflex activity can be explained by reference to a stretch-induced reflex. Thus, the primary objective of this study was to test whether the WBV-induced muscular reflex (WBV-IMR) can be explained as a stretch-induced reflex. [Subjects and Methods] The present study assessed 20 healthy males using surface electrodes placed on their right soleus muscle. The latency of the tendon reflex (T-reflex) as a stretch-induced reflex was compared with the reflex latency of the WBV-IMR. In addition, simulations were performed at 25, 30, 35, 40, 45, and 50 Hz to determine the stretch frequency of the muscle during WBV. [Results] WBV-IMR latency (40.5 ± 0.8 ms; 95% confidence interval [CI]: 39.0–41.9 ms) was significantly longer than T-reflex latency (34.6 ± 0.5 ms; 95% CI: 33.6–35.5 ms) and the mean difference was 6.2 ms (95% CI of the difference: 4.7–7.7 ms). The simulations performed in the present study demonstrated that the frequency of the stretch signal would be twice the frequency of the vibration. [Conclusion] These findings do not support the notion that WBV-IMR can be explained by reference to a stretch-induced reflex. PMID:26310784

  2. Variability in Hoffmann and tendon reflexes in healthy male subjects

    NASA Technical Reports Server (NTRS)

    Good, E.; Do, S.; Jaweed, M.

    1992-01-01

    There is a time dependent decrease in amplitude of H- and T-reflexes during Zero-G exposure and subsequently an increase in the amplitude of the H-reflex 2-4 hours after return to a 1-G environment. These alterations have been attributed to the adaptation of the human neurosensory system to gravity. The Hoffman reflex (H-reflex) is an acknowledged method to determine the integrity of the monosynaptic reflex arc. However deep tendon reflexes (DTR's or T-reflexes), elicited by striking the tendon also utilize the entire reflex arc. The objective of this study was to compare the variability in latency and amplitude of the two reflexes in healthy subjects. Methods: Nine healthy male subjects, 27-43 years in age, 161-175 cm in height plus 60-86 Kg in weight, underwent weekly testing for four weeks with a Dan-Tec EMG counterpoint EMG system. Subjects were studied prone and surface EMG electrodes were placed on the right and left soleus muscles. The H-reflex was obtained by stimulating the tibial nerve in the politeal fossa with a 0.2 msec square wave pulse delivered at 2 Hz until the maximum H-reflex was obtained. The T-reflex was invoked by tapping the achilles tendon with a self triggering reflex hammer connected to the EMG system. The latencies and amplitudes for the H- and T-reflexes were measured. Results: These data indicate that the amplitudes of these reflexes varied considerably. However, latencies to invoked responses were consistent. The latency of the T-reflex was approximately 3-5 msec longer than the H-reflex. Conclusion: The T-reflex is easily obtained, requires less time, and is more comfortable to perform. Qualitative data can be obtained by deploying self triggering, force plated reflex hammers both in the 1-G and Zero-G environment.

  3. Jaw, blink and corneal reflex latencies in multiple sclerosis.

    PubMed Central

    Sanders, E A; Ongerboer de Visser, B W; Barendswaard, E C; Arts, R J

    1985-01-01

    Jaw, blink and corneal reflexes, which all involve the trigeminal system, were recorded in 54 patients with multiple sclerosis; thirty-seven of these patients were classified as having definite multiple sclerosis and 17 as indefinite multiple sclerosis, according to Schumacher's criteria. The jaw reflex was abnormal less frequently than either of the other two reflexes, but in four cases it was the only abnormal reflex found. Testing a combination of two or three trigeminal reflexes did not yield a higher incidence of abnormalities than testing the blink or corneal reflex alone. Nine patients showed abnormal reflexes which were unexpected on the basis of clinical symptoms. The combined recordings demonstrate at least one abnormal reflex in 74% of the patients. The various types of reflex abnormalities reflect major damage to different parts of the trigeminal system and may therefore make an important contribution to the diagnosis of multiple sclerosis. PMID:4087004

  4. The trigeminocardiac reflex – a comparison with the diving reflex in humans

    PubMed Central

    Lemaitre, Frederic; Schaller, Bernhard

    2015-01-01

    The trigeminocardiac reflex (TCR) has previously been described in the literature as a reflexive response of bradycardia, hypotension, and gastric hypermotility seen upon mechanical stimulation in the distribution of the trigeminal nerve. The diving reflex (DR) in humans is characterized by breath-holding, slowing of the heart rate, reduction of limb blood flow and a gradual rise in the mean arterial blood pressure. Although the two reflexes share many similarities, their relationship and especially their functional purpose in humans have yet to be fully elucidated. In the present review, we have tried to integrate and elaborate these two phenomena into a unified physiological concept. Assuming that the TCR and the DR are closely linked functionally and phylogenetically, we have also highlighted the significance of these reflexes in humans. PMID:25995761

  5. Audiogenic reflex seizures in cats

    PubMed Central

    Lowrie, Mark; Bessant, Claire; Harvey, Robert J; Sparkes, Andrew; Garosi, Laurent

    2015-01-01

    Objectives This study aimed to characterise feline audiogenic reflex seizures (FARS). Methods An online questionnaire was developed to capture information from owners with cats suffering from FARS. This was collated with the medical records from the primary veterinarian. Ninety-six cats were included. Results Myoclonic seizures were one of the cardinal signs of this syndrome (90/96), frequently occurring prior to generalised tonic–clonic seizures (GTCSs) in this population. Other features include a late onset (median 15 years) and absence seizures (6/96), with most seizures triggered by high-frequency sounds amid occasional spontaneous seizures (up to 20%). Half the population (48/96) had hearing impairment or were deaf. One-third of cats (35/96) had concurrent diseases, most likely reflecting the age distribution. Birmans were strongly represented (30/96). Levetiracetam gave good seizure control. The course of the epilepsy was non-progressive in the majority (68/96), with an improvement over time in some (23/96). Only 33/96 and 11/90 owners, respectively, felt the GTCSs and myoclonic seizures affected their cat’s quality of life (QoL). Despite this, many owners (50/96) reported a slow decline in their cat’s health, becoming less responsive (43/50), not jumping (41/50), becoming uncoordinated or weak in the pelvic limbs (24/50) and exhibiting dramatic weight loss (39/50). These signs were exclusively reported in cats experiencing seizures for >2 years, with 42/50 owners stating these signs affected their cat’s QoL. Conclusions and relevance In gathering data on audiogenic seizures in cats, we have identified a new epilepsy syndrome named FARS with a geriatric onset. Further studies are warranted to investigate potential genetic predispositions to this condition. PMID:25916687

  6. Volume production of negative ions in the reflex type ion source

    SciTech Connect

    Jimbo, K.

    1982-01-01

    The production of negative hydrogen ions is investigated in the reflex-type negative ion source. The extracted negative hydrogen currents of 9.7 mA (100 mA/cm/sup 2/) for H/sup -/ and of 4.1 mA (42 mA/cm/sup 2/) for D/sup -/ are obtained continuously. The impurity is less then 1%. An isotope effect of negative ion production is observed. When anomalous diffusion in the positive column was found by Lehnert and Hoh (1960), it was pointed out that the large particle loss produced by anomalous diffusion is compensated by the large particle production inside the plasma, i.e., the plasma tries to maintain itself. The self-sustaining property of the plasma is applied to the reflex-type negative ion source. Anomalous diffusion was artificially encouraged by changing the radial electric field inside the reflex discharge. The apparent encouragement of negative ion diffusion by the increase of density fluctuation amplitude is observed. Twice as much negative ion current was obtained with the artificial encouragement as without. It is found from the quasilinear theory that the inwardly directed radial electric field destabilizes the plasma in the reflex-type ion source. The nonlinear theory based on Yoshikawa method (1962) is extended, and the anomalous diffusion coefficient in a weakly ionized plasma is obtained. The electrostatic sheath trap, which increases the confinement of negative ions in the reflex-type ion source, is also discussed.

  7. The reflex-diode HPM source on Aurora

    SciTech Connect

    Huttlin, G.A.; Bushell, M.S.; Conrad, D.B.; Davis, D.P.; Litz, M.S.; Ruth, B.G.; Agee, F.J. ); Ebersole, K.L.; Judy, D.C.; Lezcano, P.A.; Pereira, N.R.; Weidenheimer, D.M. )

    1990-06-01

    This paper describes the most recent in a series of experiments to develop the reflex diode as a source of microwaves on the Aurora relativistic electron-beam pulser. The authors have achieved an overall output for radial extraction of {approximately} 400 J in microwave bursts from {approximately} 100 to 150 ns at frequencies below 1 GHz. The diagnostics for radial extraction have included directional couplers, card calorimeters, and free-field sensors. The authors have varied the anode/cathode spacing, downstream microwave reflector, and a second anode foil, but, within the range of variations, no strong trends have been noted.

  8. Using ESO Reflex with Web Services

    NASA Astrophysics Data System (ADS)

    Järveläinen, P.; Savolainen, V.; Oittinen, T.; Maisala, S.; Ullgrén, M. Hook, R.

    2008-08-01

    ESO Reflex is a prototype graphical workflow system, based on Taverna, and primarily intended to be a flexible way of running ESO data reduction recipes along with other legacy applications and user-written tools. ESO Reflex can also readily use the Taverna Web Services features that are based on the Apache Axis SOAP implementation. Taverna is a general purpose Web Service client, and requires no programming to use such services. However, Taverna also has some restrictions: for example, no numerical types such integers. In addition the preferred binding style is document/literal wrapped, but most astronomical services publish the Axis default WSDL using RPC/encoded style. Despite these minor limitations we have created simple but very promising test VO workflow using the Sesame name resolver service at CDS Strasbourg, the Hubble SIAP server at the Multi-Mission Archive at Space Telescope (MAST) and the WESIX image cataloging and catalogue cross-referencing service at the University of Pittsburgh. ESO Reflex can also pass files and URIs via the PLASTIC protocol to visualisation tools and has its own viewer for VOTables. We picked these three Web Services to try to set up a realistic and useful ESO Reflex workflow. They also demonstrate ESO Reflex abilities to use many kind of Web Services because each of them requires a different interface. We describe each of these services in turn and comment on how it was used

  9. A large receptive-expressive gap in bilingual children.

    PubMed

    Keller, Karin; Troesch, Larissa M; Grob, Alexander

    2015-01-01

    The present study focuses on the discrepancy between receptive and expressive language competence among bilingual children and tests possible explanatory factors of this gap. The sample consisted of 406 bilingual children with German as their second language (L2) and 46 different first languages. Receptive and expressive German language competence (L2) were measured with a standardized language development test at the age of 43 months. As expected, a significant gap in receptive and expressive German language competence (L2) emerged in all language groups. The size of the gap reached 1 SD and correlated with the amount of language contact and thus provides support for the language exposure hypothesis. However, we found no evidence for the language familiarity hypothesis. The present study contributes to the understanding of mechanisms in bilingual language development and, hence, is consequential for both basic research and language assessment practice. PMID:26379601

  10. Relating plastic changes of short latency human soleus stretch reflex to changes in task performance induced by training.

    PubMed

    Kundert, Robinson; Yagi, Tohru

    2012-01-01

    Recent findings in the field of neurophysiology showed that operant conditioning on the human H-Reflex is possible. This leads to many possible clinical applications as well as possible sophisticated training methods for athletes. Although stretch reflexes have been subject to extensive literature, knowledge about the influence of short latency stretch reflexes on task performance is lacking. Within this study an ankle control task was designed where perturbations in the magnitude of functional relevance were applied. Results analyzing angle over time after perturbation confirm previous findings which used to analyze the EMG and force response to ankle perturbations. Further it was found that after training the response to perturbations shifted from initially containing latencies which indicate conscious support by transcortical pathways to latencies which could only origin from unconscious stretch reflex responses. The trend of the short latency response to shift towards the long latency response and to diminish, while pre-defined performance criteria improved, denote a functional relevance of the short latency stretch reflex to task performance. Whereas short latency reflexes have any importance at all or if improvements emerge only out of enhancements in the long latency response future work making use of operant conditioning on the short latency H-Reflex will have to unravel. PMID:23366715

  11. Reception of Multiple Telemetry Signals via One Dish Antenna

    NASA Technical Reports Server (NTRS)

    Mukai, Ryan; Vilnrotter, Victor

    2010-01-01

    A microwave aeronautical-telemetry receiver system includes an antenna comprising a seven-element planar array of receiving feed horns centered at the focal point of a paraboloidal dish reflector that is nominally aimed at a single aircraft or at multiple aircraft flying in formation. Through digital processing of the signals received by the seven feed horns, the system implements a method of enhanced cancellation of interference, such that it becomes possible to receive telemetry signals in the same frequency channel simultaneously from either or both of two aircraft at slightly different angular positions within the field of view of the antenna, even in the presence of multipath propagation. The present system is an advanced version of the system described in Spatio- Temporal Equalizer for a Receiving-Antenna Feed Array NPO-43077, NASA Tech Briefs, Vol. 34, No. 2 (February 2010), page 32. To recapitulate: The radio-frequency telemetry signals received by the seven elements of the array are digitized, converted to complex baseband form, and sent to a spatio-temporal equalizer that consists mostly of a bank of seven adaptive finite-impulse-response (FIR) filters (one for each element in the array) plus a unit that sums the outputs of the filters. The combination of the spatial diversity of the feedhorn array and the temporal diversity of the filter bank affords better multipath suppression performance than is achievable by means of temporal equalization alone. The FIR filter bank adapts itself in real time to enable reception of telemetry at a low bit error rate, even in the presence of frequency-selective multipath propagation like that commonly found at flight-test ranges. The combination of the array and the filter bank makes it possible to constructively add multipath incoming signals to the corresponding directly arriving signals, thereby enabling reductions in telemetry bit-error rates.

  12. Neural reflexes in inflammation and immunity

    PubMed Central

    2012-01-01

    The mammalian immune system and the nervous system coevolved under the influence of infection and sterile injury. Knowledge of homeostatic mechanisms by which the nervous system controls organ function was originally applied to the cardiovascular, gastrointestinal, musculoskeletal, and other body systems. Development of advanced neurophysiological and immunological techniques recently enabled the study of reflex neural circuits that maintain immunological homeostasis, and are essential for health in mammals. Such reflexes are evolutionarily ancient, dating back to invertebrate nematode worms that possess primitive immune and nervous systems. Failure of these reflex mechanisms in mammals contributes to nonresolving inflammation and disease. It is also possible to target these neural pathways using electrical nerve stimulators and pharmacological agents to hasten the resolution of inflammation and provide therapeutic benefit. PMID:22665702

  13. Laryngeal Reflexes: Physiology, Technique and Clinical Use

    PubMed Central

    Ludlow, Christy L.

    2015-01-01

    This review examines the current level of knowledge and techniques available for the study of laryngeal reflexes. Overall, the larynx is under constant control of several systems (including respiration, swallowing and cough) as well as sensory-motor reflex responses involving glossopharyngeal, pharyngeal, laryngeal and tracheobronchial sensory receptors. Techniques for the clinical assessment of these reflexes are emerging and need to be examined for sensitivity and specificity in identifying laryngeal sensory disorders. Quantitative assessment methods for the diagnosis of sensory reductions as well as sensory hypersensitivity may account for laryngeal disorders such as chronic cough, paradoxical vocal fold disorder and muscular tension dysphonia. The development of accurate assessment techniques could improve our understanding of the mechanisms involved in these disorders. PMID:26241237

  14. A reflex resonance model of vocal vibrato.

    PubMed

    Titze, Ingo R; Story, Brad; Smith, Marshall; Long, Russel

    2002-05-01

    A reflex mechanism with a long latency (>40 ms) is implicated as a plausible cause of vocal vibrato. At least one pair of agonist-antagonist muscles that can change vocal-fold length is needed, such as the cricothyroid muscle paired with the thyroarytenoid muscle, or the cricothyroid muscle paired with the lateral cricoarytenoid muscle or a strap muscle. Such an agonist-antagonist muscle pair can produce negative feedback instability in vocal-fold length with this long reflex latency, producing oscillations on the order of 5-7 Hz. It is shown that singers appear to increase the gain in the reflex loop to cultivate the vibrato, which grows out of a spectrum of 0-15-Hz physiologic tremors in raw form. PMID:12051447

  15. A reflex resonance model of vocal vibrato

    NASA Astrophysics Data System (ADS)

    Titze, Ingo R.; Story, Brad; Smith, Marshall; Long, Russel

    2002-05-01

    A reflex mechanism with a long latency (>40 ms) is implicated as a plausible cause of vocal vibrato. At least one pair of agonist-antagonist muscles that can change vocal-fold length is needed, such as the cricothyroid muscle paired with the thyroarytenoid muscle, or the cricothyroid muscle paired with the lateral cricoarytenoid muscle or a strap muscle. Such an agonist-antagonist muscle pair can produce negative feedback instability in vocal-fold length with this long reflex latency, producing oscillations on the order of 5-7 Hz. It is shown that singers appear to increase the gain in the reflex loop to cultivate the vibrato, which grows out of a spectrum of 0-15-Hz physiologic tremors in raw form.

  16. Reflexive composites: self-healing composite structures

    NASA Astrophysics Data System (ADS)

    Margraf, Thomas W., Jr.; Barnell, Thomas J.; Havens, Ernie; Hemmelgarn, Christopher D.

    2008-03-01

    Cornerstone Research Group Inc. has developed reflexive composites achieving increased vehicle survivability through integrated structural awareness and responsiveness to damage. Reflexive composites can sense damage through integrated piezoelectric sensing networks and respond to damage by heating discrete locations to activate the healable polymer matrix in areas of damage. The polymer matrix is a modified thermoset shape memory polymer that heals based on phenomena known as reptation. In theory, the reptation healing phenomena should occur in microseconds; however, during experimentation, it has been observed that to maximize healing and restore up to 85 % of mechanical properties a healing cycle of at least three minutes is required. This paper will focus on work conducted to determine the healing mechanisms at work in CRG's reflexive composites, the optimal healing cycles, and an explanation of the difference between the reptation model and actual healing times.

  17. Reflex: Graphical workflow engine for data reduction

    NASA Astrophysics Data System (ADS)

    ESO Reflex development Team

    2014-01-01

    Reflex provides an easy and flexible way to reduce VLT/VLTI science data using the ESO pipelines. It allows graphically specifying the sequence in which the data reduction steps are executed, including conditional stops, loops and conditional branches. It eases inspection of the intermediate and final data products and allows repetition of selected processing steps to optimize the data reduction. The data organization necessary to reduce the data is built into the system and is fully automatic; advanced users can plug their own modules and steps into the data reduction sequence. Reflex supports the development of data reduction workflows based on the ESO Common Pipeline Library. Reflex is based on the concept of a scientific workflow, whereby the data reduction cascade is rendered graphically and data seamlessly flow from one processing step to the next. It is distributed with a number of complete test datasets so users can immediately start experimenting and familiarize themselves with the system.

  18. Physiopharmacology of the peristaltic reflex: an update.

    PubMed

    De Ponti, F; Cosentino, M; Lecchini, S; Frigo, G M; Crema, A

    1991-06-01

    The peristaltic reflex is one of the simplest models which can be used to study the function of enteric neurons by recording intestinal motor activity. Peristalsis consists of a coordinated, aborally propagating motor activity which requires the functional integrity of receptor pathways, excitatory and inhibitory neural pathways and neuromuscular junctions. Luminal distension elicits polarized responses: an ascending excitatory response (ascending contraction) and a descending inhibitory response (descending relaxation). The present paper reviews the most recent acquisitions on the neural pathways and neurotransmitters involved in the regulation of the peristaltic reflex.

  19. A tangibly reinforced speech reception threshold procedure for use with small children.

    PubMed

    Martin, F N; Coombes, S

    1976-08-01

    Forty normal-hearing children between 17 and 56 months were tested using a new method for determining speech reception thresholds. The words employed were names for parts of a device that was in the form of a colorful clown. The device automatically rewarded the child with a small piece of candy each time he pressed the part of the clown that had been announced through the sound field system of a speech audiometer. Results showed that operant conditioning speech audiometry using tangible reinforcers is feasible for small children. Both boys and girls can be tested accurately by this method down to age two and one-half years.

  20. F response and H reflex analysis of physiological unity of gravity and antigravity muscles in man.

    PubMed

    García, H A; Fisher, M A

    1977-01-01

    Observational differences between reflex (H reflex) and antidromic (F response) activation of segmental motoneurons by a peripheral electrical stimulus are described. In contrast to H reflexes, the percentage of F responses found after a series of stimuli is directly related to the pick-up field of the recording electrode consistent with this response being due to the variable activation of a small fraction of the available motoneuron pool. Despite the differing physiological mechanisms, both F responses and H reflexes can be used to demonstrate similar relative "central excitatory states" for antigravity muscles (i.e. extensors in the lower extremity and flexors in the upper extremity) and their antagonist gravity muscles. H reflexes were elicited not only in their usual location in certain antigravity muscles but also in unusual locations by length/tension changes in agonist and antagonist groups as well as by passive stretch. The data argue for the physiological unity of similarly acting gravity and antigravity muscles as well as supporting a meaningful role of group II afferents in normal segmental motoneuron pool excitability.

  1. Evaluating the Reflexive Practices in a Learning Experience

    ERIC Educational Resources Information Center

    Bruno, Andreina; Galuppo, Laura; Gilardi, Silvia

    2011-01-01

    Reflexivity is a primary requirement for professional work. Our aim was to describe a methodology suitable for detecting the development of reflexive practice through the analysis of 59 Master's degree students' journals. We explore the use and changes of reflexive practice in relation to the settings and activities of the course using analysis of…

  2. On Reflection: Is Reflexivity Necessarily Beneficial in Intercultural Education?

    ERIC Educational Resources Information Center

    Blasco, Maribel

    2012-01-01

    This article explores how the concept of reflexivity is used in intercultural education. Reflexivity is often presented as a key learning goal in acquiring intercultural competence (ICC). Yet, reflexivity can be defined in different ways, and take different forms across time and space, depending on the concepts of selfhood that prevail and how…

  3. 33 CFR 158.410 - Reception facilities: General.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) POLLUTION RECEPTION FACILITIES FOR OIL, NOXIOUS LIQUID SUBSTANCES, AND GARBAGE Criteria for... CFR 261.3, unless the port or terminal operator can provide to the master, operator, or person in... ship departs from the yard. Note: The U.S. Department of Agriculture's Animal and Plant...

  4. Concern About Hunger May Increase Receptivity to GMOs.

    PubMed

    Carter, B Elijah; Conn, Caitlin C; Wiles, Jason R

    2016-07-01

    Due to a phenomenon known as the 'backfire effect', intuition-based opinions can be inadvertently strengthened by evidence-based counterarguments. Students' views on genetically modified organisms (GMOs) may be subject to this effect. We explored the impact of an empathetically accessible topic, world hunger, on receptivity to GMO technology as an alternative to direct evidence-based approaches. PMID:27246454

  5. Receptive Vocabulary Differences in Monolingual and Bilingual Adults

    ERIC Educational Resources Information Center

    Bialystok, Ellen; Luk, Gigi

    2012-01-01

    English receptive vocabulary scores from 797 monolingual and 808 bilingual participants between the ages of 17 and 89 years old were aggregated from 20 studies to compare standard scores across language groups. The distribution of scores was unimodal for both groups but the mean score was significantly different, with monolinguals obtaining higher…

  6. Boundary-Layer Receptivity and Integrated Transition Prediction

    NASA Technical Reports Server (NTRS)

    Chang, Chau-Lyan; Choudhari, Meelan

    2005-01-01

    The adjoint parabold stability equations (PSE) formulation is used to calculate the boundary layer receptivity to localized surface roughness and suction for compressible boundary layers. Receptivity efficiency functions predicted by the adjoint PSE approach agree well with results based on other nonparallel methods including linearized Navier-Stokes equations for both Tollmien-Schlichting waves and crossflow instability in swept wing boundary layers. The receptivity efficiency function can be regarded as the Green's function to the disturbance amplitude evolution in a nonparallel (growing) boundary layer. Given the Fourier transformed geometry factor distribution along the chordwise direction, the linear disturbance amplitude evolution for a finite size, distributed nonuniformity can be computed by evaluating the integral effects of both disturbance generation and linear amplification. The synergistic approach via the linear adjoint PSE for receptivity and nonlinear PSE for disturbance evolution downstream of the leading edge forms the basis for an integrated transition prediction tool. Eventually, such physics-based, high fidelity prediction methods could simulate the transition process from the disturbance generation through the nonlinear breakdown in a holistic manner.

  7. Learning to Converse in a Foreign Language: The RECEPTION GAME.

    ERIC Educational Resources Information Center

    Kaplan, Marsha A.

    1997-01-01

    The RECEPTION GAME teaches conversation skills to adult foreign language learners with positions in international business and diplomacy. The design combines elements of simulation and experiential learning and takes into account conversation's rapport-building function, turn-taking mechanisms, open-ended structure, listening demands for following…

  8. On the Reception of Foucauldian Ideas in Pedagogical Research

    ERIC Educational Resources Information Center

    Ostrowicka, Helena

    2011-01-01

    The article is devoted to the presentation of the reception of Foucauldian ideas in Polish pedagogical research over the past twenty years. This movement of thought is described as an oscillation between heterotopia and utopia, autonomy and heteronomy, emancipation and repression. As results of this analysis indicate, Polish pedagogues are most…

  9. Communication Based on Receptive Multilingualism: Advantages and Disadvantages

    ERIC Educational Resources Information Center

    Braunmüller, Kurt

    2013-01-01

    This paper tries to give answers for successful receptive multilingualism (RM) but also for its failure. It is mainly based on the results of two projects, one on inter-dialectal communication in the Baltic area during the era of the Hanseatic League and the other analyses inter-Scandinavian communication today. The main purpose of this survey is…

  10. Reception-Conversion Subsystem (RXCV) for microwave power transmission system

    NASA Technical Reports Server (NTRS)

    1975-01-01

    As part of a program to demonstrate the feasibility of power transmission from space, an approximately 25 sq m Reception-Conversion Subsystem was designed and tested. The device collects high power microwave energy, converts it into dc, and dissipates it in an instrumented demonstration load.

  11. Views of the Apollo 11 Twentieth Anniversary Black Tie reception

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Views of the Apollo 11 Twentieth Anniversary Black Tie reception at the downtown Houston Hyatt Regency Hotel. Views include former JSC Directors Robert Gilruth and Christopher C. Kraft Jr. reminiscing with keynote speaker Walter Cronkite (39934); Apollo astronauts Tom Stafford (left) and Neil Armstrong (right) talk with former Soviet cosmonaut Alexei Leonov (center) at the gala (39935).

  12. Ovarian fluid of receptive females enhances sperm velocity.

    PubMed

    Gasparini, Clelia; Andreatta, Gabriele; Pilastro, Andrea

    2012-05-01

    The females of several internal fertilizers are able to store sperm for a long time, reducing the risk of sperm limitation. However, it also means that males can attempt to mate outside females' receptive period, potentially increasing the level of sperm competition and exacerbating sexual conflict over mating. The guppy (Poecilia reticulata), an internally fertilizing fish, is a model system of such competition and conflict. Female guppies accept courtship and mate consensually only during receptive periods of the ovarian cycle but receive approximately one (mostly forced) mating attempt per minute both during and outside their sexually receptive phase. In addition, females can store viable sperm for months. We expected that guppy females would disfavour sperm received during their unreceptive period, possibly by modulating the quality and/or quantity of the components present in the ovarian fluid (OF) over the breeding cycle. Ovarian fluid has been shown to affect sperm velocity, a determinant of sperm competition success in this and other fishes. We found that in vitro sperm velocity is slower in OF collected from unreceptive females than in OF from receptive females. Visual stimulation with a potential partner prior to collection did not significantly affect in vitro sperm velocity. These results suggest that sperm received by unreceptive females may be disfavoured as sperm velocity likely affects the migration process and the number of sperm that reach storage sites.

  13. Categorization Skills and Receptive Language Development in Autistic Children.

    ERIC Educational Resources Information Center

    Ungerer, Judy A.; Sigman, Marian

    1987-01-01

    Assessment of category knowledge and receptive language skills of 16 autistic (3-6 years old), mentally retarded, and normal children indicated that the autistic children's knowledge of function, form, and color categories was comparable to that of the mental-age-matched mentally retarded and normal comparison groups. (Author/DB)

  14. Reception hall, inside front entrance facing toward stairs to second ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Reception hall, inside front entrance facing toward stairs to second floor - Fitzsimons General Hospital, Bachelor Officers' Quarters/Officers' Club, West Harlowe Avenue, South side, 200 feet West of intersection of West Harlow Avenue & South First Street, Aurora, Adams County, CO

  15. Cued Speech and the Reception of Spoken Language.

    ERIC Educational Resources Information Center

    Nicholls, Gaye H.; Ling, Daniel

    1982-01-01

    The Australian study investigated the effect of cued speech on the speech reception abilities of 18 profoundly hearing impaired children under seven conditions of presentation: audition; lipreading; audition and lipreading; cues; audition and cues; lipreading and cues; and audition, lipreading, and cues. (Author)

  16. Integrated Parallel Reception, Excitation, and Shimming (iPRES)

    PubMed Central

    Han, Hui; Song, Allen W.; Truong, Trong-Kha

    2013-01-01

    Purpose To develop a new concept for a hardware platform that enables integrated parallel reception, excitation, and shimming (iPRES). Theory This concept uses a single coil array rather than separate arrays for parallel excitation/reception and B0 shimming. It relies on a novel design that allows a radiofrequency current (for excitation/reception) and a direct current (for B0 shimming) to coexist independently in the same coil. Methods Proof-of-concept B0 shimming experiments were performed with a two-coil array in a phantom, whereas B0 shimming simulations were performed with a 48-coil array in the human brain. Results Our experiments show that individually optimized direct currents applied in each coil can reduce the B0 root-mean-square error by 62–81% and minimize distortions in echo-planar images. The simulations show that dynamic shimming with the 48-coil iPRES array can reduce the B0 root-mean-square error in the prefrontal and temporal regions by 66–79% as compared to static 2nd-order spherical harmonic shimming and by 12–23% as compared to dynamic shimming with a 48-coil conventional shim array. Conclusion Our results demonstrate the feasibility of the iPRES concept to perform parallel excitation/reception and B0 shimming with a unified coil system as well as its promise for in vivo applications. PMID:23629974

  17. Adolescent Weight Status and Receptivity to Food TV Advertisements

    ERIC Educational Resources Information Center

    Adachi-Mejia, Anna M.; Sutherland, Lisa A.; Longacre, Meghan R.; Beach, Michael L.; Titus-Ernstoff, Linda; Gibson, Jennifer J.; Dalton, Madeline A.

    2011-01-01

    Objective: This study examined the relationship between adolescent weight status and food advertisement receptivity. Design: Survey-based evaluation with data collected at baseline (initial and at 2 months), and at follow-up (11 months). Setting: New Hampshire and Vermont. Participants: Students (n = 2,281) aged 10-13 in 2002-2005. Main Outcome…

  18. Concern About Hunger May Increase Receptivity to GMOs.

    PubMed

    Carter, B Elijah; Conn, Caitlin C; Wiles, Jason R

    2016-07-01

    Due to a phenomenon known as the 'backfire effect', intuition-based opinions can be inadvertently strengthened by evidence-based counterarguments. Students' views on genetically modified organisms (GMOs) may be subject to this effect. We explored the impact of an empathetically accessible topic, world hunger, on receptivity to GMO technology as an alternative to direct evidence-based approaches.

  19. Joint Book Reading and Receptive Vocabulary: A Parallel Process Model

    ERIC Educational Resources Information Center

    Meng, Christine

    2016-01-01

    The purpose of the present study was to understand the reciprocal, bidirectional longitudinal relation between joint book reading and English receptive vocabulary. To address the research goals, a nationally representative sample of Head Start children, the Head Start Family and Child Experiences Survey (2003 cohort), was used for analysis. The…

  20. Receptive Language of Gifted and Learning Disabled-Gifted Children.

    ERIC Educational Resources Information Center

    Chermak, Gail D.; Burgerud, Donna M.

    1983-01-01

    Thirty elementary school children in regular, gifted, and learning disabled-gifted programs were examined on three receptive language tests. Analysis of variance indicated that the "Token Test for Children" differentiated learning disabled-gifted, and the "Detroit Tests of Learning Aptitude, Verbal Absurdities Subtest" differentiated gifted…

  1. Listen to Your Heart? Calling and Receptivity to Career Advice

    ERIC Educational Resources Information Center

    Dobrow, Shoshana R.; Tosti-Kharas, Jennifer

    2012-01-01

    This study explores calling in the context of career decision making. Specifically, the authors examine receptivity to advice that discourages individuals from pursuing a professional path in their calling's domain. The authors hypothesize that people with a strong calling will be more likely to ignore negative career advice. In Study 1, a…

  2. Making Sense of Science in the Reception Class

    ERIC Educational Resources Information Center

    Glauert, Esme

    2005-01-01

    In the context of growing awareness of young children's capabilities, and debates about the nature of their reasoning in science, this study set out to explore the ways in which reception children make sense of classroom experiences in science. A particular challenge of the study was to develop appropriate and productive approaches to…

  3. College Student Receptiveness to Various Alcohol Treatment Options

    ERIC Educational Resources Information Center

    Epler, Amee J.; Sher, Kenneth J.; Loomis, Tiffany B.; O'Malley, Stephanie S.

    2009-01-01

    Objective: Heavy episodic drinking remains a significant problem on college campuses. Although most interventions for college students are behavioral, pharmacological treatments, such as naltrexone, could provide additional options. Participants: The authors evaluated receptivity to various alcohol treatment options in a general population of…

  4. Intervention for Mixed Receptive-Expressive Language Impairment: A Review

    ERIC Educational Resources Information Center

    Boyle, James; McCartney, Elspeth; O'Hare, Anne; Law, James

    2010-01-01

    Studies indicate that language impairment that cannot be accounted for by factors such as below-average non-verbal ability, hearing impairment, behaviour or emotional problems, or neurological impairments affects some 6% of school-age children. Language impairment with a receptive language component is more resistant to intervention than specific…

  5. Language Production and Reception: A Processability Theory Study

    ERIC Educational Resources Information Center

    Spinner, Patti

    2013-01-01

    Pienemann's Processability Theory (PT) predicts an order of emergence of morphosyntactic elements in second language (L2) production data. This research investigates whether the same order of emergence can be detected in L2 reception data, specifically, data from a timed audio grammaticality judgment task (GJT). The results from three related…

  6. A Psychometric Evaluation of the Cultural Receptivity in Fostering Scale

    ERIC Educational Resources Information Center

    Coakley, Tanya M.; Orme, John G.

    2006-01-01

    Objective: The psychometric properties of a new measure of foster parents' openness toward participating in activities that promote children's cultural development are evaluated. The measure is titled the Cultural Receptivity in Fostering Scale (CRFS). Method: Data from 304 foster mothers who completed the CRFS and a battery of measures on…

  7. Expressive versus Receptive Language Skills in Specific Reading Disorder

    ERIC Educational Resources Information Center

    Stojanovik, Vesna; Riddell, Patricia

    2008-01-01

    Despite ample research into the language skills of children with specific reading disorder no studies so far have investigated whether there may be a difference between expressive and receptive language skills in this population. Yet, neuro-anatomical models would predict that children who have specific reading disorder which is not associated…

  8. Ovarian fluid of receptive females enhances sperm velocity.

    PubMed

    Gasparini, Clelia; Andreatta, Gabriele; Pilastro, Andrea

    2012-05-01

    The females of several internal fertilizers are able to store sperm for a long time, reducing the risk of sperm limitation. However, it also means that males can attempt to mate outside females' receptive period, potentially increasing the level of sperm competition and exacerbating sexual conflict over mating. The guppy (Poecilia reticulata), an internally fertilizing fish, is a model system of such competition and conflict. Female guppies accept courtship and mate consensually only during receptive periods of the ovarian cycle but receive approximately one (mostly forced) mating attempt per minute both during and outside their sexually receptive phase. In addition, females can store viable sperm for months. We expected that guppy females would disfavour sperm received during their unreceptive period, possibly by modulating the quality and/or quantity of the components present in the ovarian fluid (OF) over the breeding cycle. Ovarian fluid has been shown to affect sperm velocity, a determinant of sperm competition success in this and other fishes. We found that in vitro sperm velocity is slower in OF collected from unreceptive females than in OF from receptive females. Visual stimulation with a potential partner prior to collection did not significantly affect in vitro sperm velocity. These results suggest that sperm received by unreceptive females may be disfavoured as sperm velocity likely affects the migration process and the number of sperm that reach storage sites. PMID:22430815

  9. Program Description for the Phoenix Reception and Assessment Center.

    ERIC Educational Resources Information Center

    Datema, Thea; And Others

    Phoenix Reception and Assessment Center (PRAC) is a non-secure detention and assessment center for up to 15 Wayne County delinquent, adolescent males who have been committed to the Michigan Department of Social Services for care, treatment and supervision. Adolescents, ages 12 through 18, are eligible for placement at Phoenix according to the…

  10. Perspective on the human cough reflex

    PubMed Central

    2011-01-01

    This review dissects the complex human cough reflex and suggests hypotheses about the evolutionary basis for the reflex. A mechanosensory-induced cough reflex conveys through branches of myelinated Aδ nerve fibers is not chemically reactive (i.e., capsaicin, bradykinin); possibly, its evolution is to prevent the harmful effects of aspiration of gastric or particulate contents into the lungs. This became necessary as the larynx moves closer to the opening of the esophagus as human ancestors adapt phonation over olfaction beginning less than 10 million years ago. The second type of cough reflex, a chemosensory type, is carried by unmyelinated C fibers. Supposedly, its origin dates back when prehistoric humans began living in close proximity to each other and were at risk for infectious respiratory diseases or irritant-induced lung injury. The mechanism for the latter type of cough is analogous to induced pain after tissue injury; and, it is controlled by the identical transient receptor potential vanilloid cation channel (TRPV1). The airways do not normally manifest nociceptive pain from a stimulus but the only consistent response that capsaicin and lung inflammation provoke in healthy human airways is cough. TRPA1, another excitatory ion channel, has been referred to as the "irritant receptor" and its activation also induces cough. For both types of cough, the motor responses are identical and via coordinated, precisely-timed and sequential respiratory events orchestrated by complex neuromuscular networking of the diaphragm, chest and abdominal respiratory muscles, the glottis and parts of the brain. PMID:22074326

  11. A Reflexive Model for Teaching Instructional Design.

    ERIC Educational Resources Information Center

    Shambaugh, Neal; Magliaro, Susan

    2001-01-01

    Documents a five-year study of two instructors who collaborated on formally studying their teaching of a master's level instructional design course. Outlines their views on learning, teaching, and instructional design (ID), describes the ID course, and explains the reflexive instructional model used, in which the teachers examined their teaching…

  12. Biological Motion Cues Trigger Reflexive Attentional Orienting

    ERIC Educational Resources Information Center

    Shi, Jinfu; Weng, Xuchu; He, Sheng; Jiang, Yi

    2010-01-01

    The human visual system is extremely sensitive to biological signals around us. In the current study, we demonstrate that biological motion walking direction can induce robust reflexive attentional orienting. Following a brief presentation of a central point-light walker walking towards either the left or right direction, observers' performance…

  13. Taking Control of Reflexive Social Attention

    ERIC Educational Resources Information Center

    Ristic, Jelena; Kingstone, Alan

    2005-01-01

    Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also the…

  14. Reflex Anuria After Renal Tumor Embolization

    SciTech Connect

    Kervancioglu, Selim Sirikci, Akif; Erbagci, Ahmet

    2007-04-15

    We report a case of reflex anuria after transarterial embolization of a renal tumor. Anuria developed immediately after embolization and resolved 74 hr following the procedure. We postulate that reflux anuria in our case was related to mechanoreceptors, chemoreceptors, or both, as these are stimulated by the occluded blood vessels, ischemia, and edema of the normal renal tissue of an embolized kidney.

  15. Plasma quiescence in a reflex discharge

    SciTech Connect

    Jerde, L.; Friedman, S.; Carr, W.; Seidl, M.

    1980-02-01

    A thermionic cathode reflex discharge and the plasma it produces are studied. It is found that extremely quiescent plasmas can be produced when the electron-loss rate due to classical diffusion is equal to the ion-loss rate. Particle and power balances for the quiescent plasma are obtained, and the average electron energy loss per ion produced is determined.

  16. Doing Reflexivity: Moments of Unbecoming and Becoming

    ERIC Educational Resources Information Center

    Fox, Alison; Allan, Julie

    2014-01-01

    This paper offers an account of a reflexive "trip" undertaken by a professional doctoral student and her supervisor. It presents a series of vignettes which offer an account of unbecomings and becomings encountered by the student. Making use of a dialogic approach in which the supervisor responds to the student, we suggest this method of…

  17. Dilemmas and Deliberations in Reflexive Ethnographic Research

    ERIC Educational Resources Information Center

    Robinson, Janean Valerie

    2014-01-01

    This paper traces insights into the challenges and dilemmas experienced whilst researching students' interpretations and understandings of the Behaviour Management in Schools policy in Western Australia. Journal records, supported by student transcripts, are woven together in a reflexive ethnographic journey--from the beginning phase of…

  18. Reflectivity, Reflexivity and Situated Reflective Practice

    ERIC Educational Resources Information Center

    Malthouse, Richard; Roffey-Barentsen, Jodi; Watts, Mike

    2014-01-01

    This paper describes an aspect of reflective practice referred to as situated reflective practice. The overarching theory is derived from social theories of structuration and reflexivity. In particular, from Giddens' theory of structuration, which sees social life as an interplay of agency and structure. Discussion of the research reported…

  19. Reflexive Learning: Stages towards Wisdom with Dreyfus

    ERIC Educational Resources Information Center

    McPherson, Ian

    2005-01-01

    The Dreyfus (2001) account of seven stages of learning is considered in the context of the Dreyfus (1980s) account of five stages of skill development. The two new stages, Mastery and Practical Wisdom, make more explicit certain themes implicit in the five-stage account. In this way Dreyfus (2001) encourages a more reflexive approach. The themes…

  20. A Review of Recommendations for Sequencing Receptive and Expressive Language Instruction

    ERIC Educational Resources Information Center

    Petursdottir, Anna Ingeborg; Carr, James E.

    2011-01-01

    We review recommendations for sequencing instruction in receptive and expressive language objectives in early and intensive behavioral intervention (EIBI) programs. Several books recommend completing receptive protocols before introducing corresponding expressive protocols. However, this recommendation has little empirical support, and some…

  1. Incontinence of urine due to instability of micturition reflexes: Part I. Detrusor reflex instability.

    PubMed

    Mahony, D T; Laferte, R O; Blais, D J

    1980-03-01

    Micturition reflex instability may result from malfunction of the detrusor reflex or instability of the pudendal nucleus which innervates the pelvic floor muscles and external sphincter. Detrusor instability is the result of sacral micturition reflex center (SMRC) hyperexcitability. This may be caused by underinhibition or overfacilitation of the SMRC, and there are both central and peripheral causes of each. Detrusor hypertrophy may invoke chronic overactivity of the detrusodetrusor facilitative reflex causing SMRC overfacilitation. Similarly, distal urethral stricture and/or chronic urethritis causing chronic overactivity of the urethrodetrusor facilitative reflex is a common cause of SMRC overfacilitation. Pathologic relaxation and weakness of the striated muscles of the pelvic floor and perineum resulting in underactivity of the perineodetrusor inhibitory reflex, is a common cause of SMRC underinhibition. In adult women these factors often coexist. Each may predispose to stress-induced detrusor instability and are often seen in association with, or are confused with, true stress incontinence. The distinguishing characteristics of detrusor hypertonicity and detrusor hyperreflexia are reviewed, and the various mechanisms of pseudostress incontinence and of urgency incontinence are discussed in detail.

  2. Receptivity of Flat-Plate Boundary Layer in a Non-Uniform Free Stream (Vorticity Normal to the Plate)

    NASA Technical Reports Server (NTRS)

    Kogan, M. N.; Shumilkin, V. G.; Ustinov, M. V.; Zhigulev, S. V.

    1999-01-01

    Experimental and theoretical studies of low speed leading edge boundary layer receptivity to free-stream vorticity produced by upstream wires normal to the leading edge are discussed. Data include parametric variations in leading edge configuration and details of the incident disturbance field including single and multiple wakes. The induced disturbance amplitude increases with increases in the leading edge diameter and wake interactions. Measurements agree with the theory of M. E. Goldstein.

  3. Receptive and Expressive Language Skills in Children with Cri-du-Chat Syndrome.

    ERIC Educational Resources Information Center

    Cornish, K. M.; Munir, F.

    1998-01-01

    Receptive and expressive language skills were assessed in 13 British children (ages 4-14) with cri-du-chat syndrome. Results found a discrepancy between the children's chronological ages and their presumed language ages and a receptive-expressive discrepancy, with reduced expressive skills compared to receptive skills. Remediation that focuses on…

  4. Deaf Students' Receptive and Expressive American Sign Language Skills: Comparisons and Relations

    ERIC Educational Resources Information Center

    Beal-Alvarez, Jennifer S.

    2014-01-01

    This article presents receptive and expressive American Sign Language skills of 85 students, 6 through 22 years of age at a residential school for the deaf using the American Sign Language Receptive Skills Test and the Ozcaliskan Motion Stimuli. Results are presented by ages and indicate that students' receptive skills increased with age and…

  5. Modulation of the initial light reflex during affective picture viewing.

    PubMed

    Henderson, Robert R; Bradley, Margaret M; Lang, Peter J

    2014-09-01

    An initial reflexive constriction of the pupil to stimulation-the light reflex-is primarily modulated by brightness, but is attenuated when participants are under threat of shock (i.e., fear-inhibited light reflex). The present study assessed whether the light reflex is similarly attenuated when viewing emotional pictures. Pupil diameter was recorded while participants viewed erotic, violent, and neutral scenes that were matched in brightness; scrambled versions identical in brightness were also presented as an additional control. Compared to viewing neutral scenes, the light reflex was reliably modulated by hedonic content, with significant attenuation both when viewing unpleasant as well as pleasant pictures. No differences in the light reflex were found among scrambled versions. Thus, emotional modulation of the initial light reflex is not confined to a context of fear and is not indicative of brightness differences when viewing pictures of natural scenes.

  6. Direct broadcast satellite-audio, portable and mobile reception tradeoffs

    NASA Technical Reports Server (NTRS)

    Golshan, Nasser

    1992-01-01

    This paper reports on the findings of a systems tradeoffs study on direct broadcast satellite-radio (DBS-R). Based on emerging advanced subband and transform audio coding systems, four ranges of bit rates: 16-32 kbps, 48-64 kbps, 96-128 kbps and 196-256 kbps are identified for DBS-R. The corresponding grades of audio quality will be subjectively comparable to AM broadcasting, monophonic FM, stereophonic FM, and CD quality audio, respectively. The satellite EIRP's needed for mobile DBS-R reception in suburban areas are sufficient for portable reception in most single family houses when allowance is made for the higher G/T of portable table-top receivers. As an example, the variation of the space segment cost as a function of frequency, audio quality, coverage capacity, and beam size is explored for a typical DBS-R system.

  7. The Comparative Reception of Darwinism: A Brief History

    NASA Astrophysics Data System (ADS)

    Glick, Thomas F.

    2010-06-01

    The subfield of Darwin studies devoted to comparative reception coalesced around 1971 with the planning of a conference on the subject, at the University of Texas at Austin held in April 1972. The original focus was western Europe, Russia and the United States. Subsequently a spate of studies on the Italian reception added to the Eurocentric focus. The center of activity then switched to Latin America where a group of scholars coalesced in the mid 1990s, seemingly related to the maturation of the history of science as a discrete discipline there somewhat earlier. When interest in Europe revived during the last decade, the center of gravity had moved both eastward, to the former Society bloc countries (a reflection of the institutionalization of the history of science there), and north to Scandinavia. Recently, interest in the topic has emerged in the Islamic World. The subtext of the expansion of this topic is modernization.

  8. Reflex sympathetic dystrophy associated with antiepileptic drugs.

    PubMed

    Falasca, G F; Toly, T M; Reginato, A J; Schraeder, P L; O'Connor, C R

    1994-01-01

    Reflex sympathetic dystrophy syndrome (RSDS) complicating antiepileptic drug (AED) therapy is not well acknowledged in the neurologic literature. We report 4 patients with reflex sympathetic dystrophy that occurred while they were receiving AEDs. All patients had shoulder and hand involvement, which in 2 was bilateral, and 1 had ipsilateral foot involvement. Two patients did not respond to a change in AEDs, but all improved with a course of prednisone. One patient with phenobarbital (PB)-associated RSDS relapsed on inadvertent rechallenge with secobarbital. A review of the literature showed that several other fibrosing disorders are associated with AED administration, including Dupuytren's contractures, frozen shoulder, plantar and hand nodules, and Peyronie's disease. RSD associated with AEDs is important to recognize because it may result in permanent disability if treatment is delayed.

  9. The spinal reflex cannot be perceptually separated from voluntary movements.

    PubMed

    Ghosh, Arko; Haggard, Patrick

    2014-01-01

    Both voluntary and involuntary movements activate sensors in the muscles, skin, tendon and joints. As limb movement can result from a mixture of spinal reflexes and voluntary motor commands, the cortical centres underlying conscious proprioception might either aggregate or separate the sensory inputs generated by voluntary movements from those generated by involuntary movements such as spinal reflexes. We addressed whether healthy volunteers could perceive the contribution of a spinal reflex during movements that combined both reflexive and voluntary contributions. Volunteers reported the reflexive contribution in leg movements that were partly driven by the knee-jerk reflex induced by a patellar tendon tap and partly by voluntary motor control. In one condition, participants were instructed to kick back in response to a tendon tap. The results were compared to reflexes in a resting baseline condition without voluntary movement. In a further condition, participants were instructed to kick forwards after a tap. Volunteers reported the perceived reflex contribution by repositioning the leg to the perceived maximum displacement to which the reflex moved the leg after each tendon tap. In the resting baseline condition, the reflex was accurately perceived. We found a near-unity slope of linear regressions of perceived on actual reflexive displacement. Both the slope value and the quality of regression fit in individual volunteers were significantly reduced when volunteers were instructed to generate voluntary backward kicks as soon as they detected the tap. In the kick forward condition, kinematic analysis showed continuity of reflex and voluntary movements, but the reflex contribution could be estimated from electromyography (EMG) recording on each trial. Again, participants' judgements of reflexes showed a poor relation to reflex EMG, in contrast to the baseline condition. In sum, we show that reflexes can be accurately perceived from afferent information. However

  10. Clinical investigations of receptive and expressive musical functions after stroke.

    PubMed

    Rosslau, Ken; Steinwede, Daniel; Schröder, C; Herholz, Sibylle C; Lappe, Claudia; Dobel, Christian; Altenmüller, Eckart

    2015-01-01

    There is a long tradition of investigating various disorders of musical abilities after stroke. These impairments, associated with acquired amusia, can be highly selective, affecting only music perception (i.e., receptive abilities/functions) or expression (music production abilities), and some patients report that these may dramatically influence their emotional state. The aim of this study was to systematically test both the melodic and rhythmic domains of music perception and expression in left- and right-sided stroke patients compared to healthy subjects. Music perception was assessed using rhythmic and melodic discrimination tasks, while tests of expressive function involved the vocal or instrumental reproduction of rhythms and melodies. Our approach revealed deficits in receptive and expressive functions in stroke patients, mediated by musical expertise. Those patients who had experienced a short period of musical training in childhood and adolescence performed better in the receptive and expressive subtests compared to those without any previous musical training. While discrimination of specific musical patterns was unimpaired after a left-sided stroke, patients with a right-sided stroke had worse results for fine melodic and rhythmic analysis. In terms of expressive testing, the most consistent results were obtained from a test that required patients to reproduce sung melodies. This implies that the means of investigating production abilities can impact the identification of deficits. PMID:26124731

  11. Science Influence on Policy - A Transmission or Reception Problem? (Invited)

    NASA Astrophysics Data System (ADS)

    Carlson, D. J.

    2009-12-01

    Unfortunately we can claim very little scientific influence on climate change policies, nationally or internationally. The weak to non-existent inclusion of green (‘climate-friendly’) practices and policies in various national economic stimulus plans represents a scientific communication failure and an opportunity lost. The ineffective and inconclusive results from the Copenhagen negotiations represent a similar and equally serious failure. When communications fail we can consider errors in transmission (from science) or in reception (by policymakers). As scientists we tend to find fault with the receivers, and to identify solutions that consist, in effect, of ‘turning up’ the transmission volume. I suggest that in fact most problems lie with the transmitters. Those problems consist of speaking in transmit (scientific) terms rather than reception (economic) terms, of ignoring the necessity of converting and comparing our predictions or assessments to real world examples and terms, of misunderstanding the considerable ability of the receivers to process uncertainty, of missing many opportunities to match our transmission technologies to the modern public reception capabilities, and, most fundamentally, of failing, in key opportunities, to transmit a clear message. During IPY we have confronted each of these failures, and at least learned what we did wrong.

  12. A study of the tactual reception of sign language.

    PubMed

    Reed, C M; Delhorne, L A; Durlach, N I; Fischer, S D

    1995-04-01

    One of the natural methods of tactual communication in common use among individuals who are both deaf and blind is the tactual reception of sign language. In this method, the receiver (who is deaf-blind) places a hand (or hands) on the dominant (or both) hand(s) of the signer in order to receive, through the tactual sense, the various formational properties associated with signs. In the study reported here, 10 experienced deaf-blind users of either American Sign Language (ASL) or Pidgin Sign English (PSE) participated in experiments to determine their ability to receive signed materials including isolated signs and sentences. A set of 122 isolated signs was received with an average accuracy of 87% correct. The most frequent type of error made in identifying isolated signs was related to misperception of individual phonological components of signs. For presentation of signed sentences (translations of the English CID sentences into ASL or PSE), the performance of individual subjects ranged from 60-85% correct reception of key signs. Performance on sentences was relatively independent of rate of presentation in signs/sec, which covered a range of roughly 1 to 3 signs/sec. Sentence errors were accounted for primarily by deletions and phonological and semantic/syntactic substitutions. Experimental results are discussed in terms of differences in performance for isolated signs and sentences, differences in error patterns for the ASL and PSE groups, and communication rates relative to visual reception of sign language and other natural methods of tactual communication.

  13. Clinical investigations of receptive and expressive musical functions after stroke

    PubMed Central

    Rosslau, Ken; Steinwede, Daniel; Schröder, C.; Herholz, Sibylle C.; Lappe, Claudia; Dobel, Christian; Altenmüller, Eckart

    2015-01-01

    There is a long tradition of investigating various disorders of musical abilities after stroke. These impairments, associated with acquired amusia, can be highly selective, affecting only music perception (i.e., receptive abilities/functions) or expression (music production abilities), and some patients report that these may dramatically influence their emotional state. The aim of this study was to systematically test both the melodic and rhythmic domains of music perception and expression in left- and right-sided stroke patients compared to healthy subjects. Music perception was assessed using rhythmic and melodic discrimination tasks, while tests of expressive function involved the vocal or instrumental reproduction of rhythms and melodies. Our approach revealed deficits in receptive and expressive functions in stroke patients, mediated by musical expertise. Those patients who had experienced a short period of musical training in childhood and adolescence performed better in the receptive and expressive subtests compared to those without any previous musical training. While discrimination of specific musical patterns was unimpaired after a left-sided stroke, patients with a right-sided stroke had worse results for fine melodic and rhythmic analysis. In terms of expressive testing, the most consistent results were obtained from a test that required patients to reproduce sung melodies. This implies that the means of investigating production abilities can impact the identification of deficits. PMID:26124731

  14. Photic sneeze reflex in nephropathic cystinosis.

    PubMed

    Katz, B; Melles, R B; Swenson, M R; Schneider, J A

    1990-12-01

    Photic induced sneeze is a reflex that occurs in certain individuals after exposure to bright light. Cystinosis is an autosomal recessive inborn error of metabolism in which nonprotein cystine accumulates within lysosomes. The pathognomonic ocular manifestation of cystinosis is corneal crystal deposition. We observed photic induced sneezes during ophthalmoscopic examination in five of 19 patients with nephropathic cystinosis (26%). We report on this observation and discuss possible pathophysiological mechanisms for photic induced sneezing in cystinosis.

  15. Photic sneeze reflex in nephropathic cystinosis.

    PubMed Central

    Katz, B; Melles, R B; Swenson, M R; Schneider, J A

    1990-01-01

    Photic induced sneeze is a reflex that occurs in certain individuals after exposure to bright light. Cystinosis is an autosomal recessive inborn error of metabolism in which nonprotein cystine accumulates within lysosomes. The pathognomonic ocular manifestation of cystinosis is corneal crystal deposition. We observed photic induced sneezes during ophthalmoscopic examination in five of 19 patients with nephropathic cystinosis (26%). We report on this observation and discuss possible pathophysiological mechanisms for photic induced sneezing in cystinosis. PMID:2275931

  16. Photic sneeze reflex in nephropathic cystinosis.

    PubMed

    Katz, B; Melles, R B; Swenson, M R; Schneider, J A

    1990-12-01

    Photic induced sneeze is a reflex that occurs in certain individuals after exposure to bright light. Cystinosis is an autosomal recessive inborn error of metabolism in which nonprotein cystine accumulates within lysosomes. The pathognomonic ocular manifestation of cystinosis is corneal crystal deposition. We observed photic induced sneezes during ophthalmoscopic examination in five of 19 patients with nephropathic cystinosis (26%). We report on this observation and discuss possible pathophysiological mechanisms for photic induced sneezing in cystinosis. PMID:2275931

  17. Effects of Wall Cooling on Hypersonic Boundary Layer Receptivity Over a Cone

    NASA Technical Reports Server (NTRS)

    Kara, K.; Balakumar, P.; Kandil, O. A.

    2008-01-01

    Effects of wall cooling on the receptivity process induced by the interaction of slow acoustic disturbances in the free-stream are numerically investigated for a boundary layer flow over a 5-degrees straight cone. The free-stream Mach number is 6.0 and the Reynolds number is 7.8x10(exp 6)/ft. Both the steady and unsteady solutions are obtained by solving the full Navier-Stokes equations using 5th-order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using 3rd-order total variation diminishing (T VD) Runge-K utta scheme for time integration. Computations are performed for a cone with nose radius of 0.001 inch for adiabatic wall temperature (T(sub aw)), 0.75*T(sub aw), 0.5*T(sub aw), 0.40*T(sub aw), 0.30*T(sub aw), and 0.20*T(sub aw). Once the mean flow field is computed, disturbances are introduced at the upstream end of the computational domain. Generation of instability waves from leading edge region and receptivity of boundary layer to slow acoustic waves are investigated. Computations showed that wall cooling has strong stabilization effect on the first mode disturbances as was observed in the experiments. T ransition location moved to upstream when wall cooling was applied It is also found that the boundary layer is much more receptive to fast acoustic wave (by almost a factor of 50). When simulations performed using the same forcing frequency growth of the second mode disturbances are delayed with wall cooling and they attained values two times higher than that of adiabatic case. In 0.20*T(sub aw) case the transition Reynolds number is doubled compared to adiabatic conditions. The receptivity coefficient for adiabatic wall case (804 R) is 1.5225 and for highly cooled cones (241, and 161 R); they are in the order of 10(exp -3).

  18. Basic Gravitational Reflexes in the Larval Frog

    NASA Technical Reports Server (NTRS)

    Cochran, Stephen L.

    1996-01-01

    This investigation was designed to determine how a primitive vertebrate, the bullfrog tadpole, is able to sense and process gravitational stimuli. Because of the phylogenetic similarities of the vestibular systems in all vertebrates, the understanding of the gravitational reflexes in this relatively simple vertebrate should elucidate a skeletal framework on a elementary level, upon which the more elaborate reflexes of higher vertebrates may be constructed. The purpose of this study was to understand how the nervous system of the larval amphibian processes gravitational information. This study involved predominantly electrophysiological investigations of the isolated, alert (forebrain removed) bullfrog tadpole head. The focus of these experiments is threefold: (1) to understand from whole extraocular nerve recordings the signals sent to the eye following static gravitational tilt of the head; (2) to localize neuronal centers responsible for generating these signals through reversible pharmacological ablation of these centers; and (3) to record intracellularly from neurons within these centers in order to determine the single neuron's role in the overall processing of the center. This study has provided information on the mechanisms by which a primitive vertebrate processes gravitational reflexes.

  19. [Receptive music therapy with persons suffering from a physical handicap].

    PubMed

    Scholer, M

    2010-01-01

    Music therapy, as a part of arts therapies, is used as a therapeutical tool for restoring, maintaining and improving the mental, physical and emotional health of human beings. The main mission of receptive music therapy is not found on the performance level, but on the level of attentive and intimate music listening that is not passive at all, contributing to musical pleasure and to wellbeing. At first we introduce the basic vocabulary used in receptive music therapy, flow experience and the main dimensions (bio-psycho-social) influenced by stimulating music listening. We also present the aims of this psycho-pedagogical project: The focus lies on determining the sensitivity of physically handicapped persons to different music stimuli (music styles). In this case, we can talk of the degree of music reception. We worked in an institution for persons suffering from a physical handicap. The applied methodology is based on the psycho-musical survey by Verdeau-Paillès (1). This psychological record consists in a basic interview and a test of music listening performances leading to the construction of a summary graph and the final receptivity psychogram. An observational frame conceived by Schiltz (2) and adapted to the actual situation offers the possibility of making exact observations as to non-verbal and verbal variables during the therapeutical sessions. Thus, we can present the results of descriptive and non-parametric statistical procedures, but also the results of case studies. The statistical tests used were Wilcoxon's sign-rank test for a pre-post comparison of variables related to non-verbal and verbal behaviour (two different sessions of music therapy with similar contents) and Spearman's Rho which permitted us to compute the correlations between non-verbal expression and verbal communication (N=14). Finally we conclude that our patients considered their musical experience as very positive. The results of the personal interview and the psycho-musical survey

  20. Receptivity and Forced Response to Acoustic Disturbances in High-Speed Boundary Layers

    NASA Technical Reports Server (NTRS)

    Balakumar, P.; King, Rudolph A.; Chou, Amanda; Owens, Lewis R.; Kegerise, Michael A.

    2016-01-01

    Supersonic boundary-layer receptivity to freestream acoustic disturbances is investigated by solving the Navier-Stokes equations for Mach 3.5 flow over a sharp flat plate and a 7-deg half-angle cone. The freestream disturbances are generated from a wavy wall placed at the nozzle wall. The freestream acoustic disturbances radiated by the wavy wall are obtained by solving the linearized Euler equations. The results for the flat plate show that instability modes are generated at all the incident angles ranging from zero to highly oblique. However, the receptivity coefficient decreases by about 20 times when the incident angle increases from zero to a highly oblique angle of 68 degrees. The results for the cone show that no instability modes are generated when the acoustic disturbances impinge the cone obliquely. The results show that the perturbations generated inside the boundary layer by the acoustic disturbances are the response of the boundary layer to the external forcing. The amplitude of the forced disturbances inside the boundary layer are about 2.5 times larger than the incoming field for zero azimuthal wavenumber and they are about 1.5 times for large azimuthal wavenumbers.

  1. Molecular tracking of Salmonella spp. in chicken meat chain: from slaughterhouse reception to end cuts.

    PubMed

    Dias, Mariane Rezende; Cavicchioli, Valéria Quintana; Camargo, Anderson Carlos; Lanna, Frederico Germano Piscitelli Alvarenga; Pinto, Paulo Sérgio de Arruda; Bersot, Luciano Dos Santos; Nero, Luís Augusto

    2016-02-01

    Due to the importance of Salmonella spp. in poultry products, this study aimed to track its main contamination routes since slaughtering reception to processing of chicken end cuts. Samples from different steps of slaughtering and processing (n = 277) were collected from two chicken slaughterhouses (Sl1 and Sl2) located in Minas Gerais state, Brazil, and subjected to Salmonella spp. detection. The obtained isolates were subjected to serological identification and tested by PCR for specific Salmonella spp. genes (ompC and sifB). Also, Salmonella spp. isolates were subjected to XbaI macrorestriction and pulsed-field gel electrophoresis (PFGE). Sixty-eight samples were positive for Salmonella spp. and 172 isolates were obtained. Sl1 and Sl2 presented similar frequencies of Salmonella spp. positive samples during reception, slaughtering and processing (p > 0.05), except for higher frequencies in Sl1 for chicken carcasses after de-feathering and evisceration (p < 0.05). PFGE allowed the identification of cross contamination and persistence of Salmonella spp. strains in Sl1. The results highlighted the relevance of the initial steps of chicken slaughtering for Salmonella spp. contamination, and the pre-chilling of carcasses as an important controlling tool. In addition, the presence of Salmonella spp. in chicken end cuts samples represents a public health concern. PMID:27162388

  2. Effects of Nose Bluntness on Hypersonic Boundary-Layer Receptivity and Stability Over Cones

    NASA Technical Reports Server (NTRS)

    Kara, Kursat; Balakumar, Ponnampalam; Kandil, Osama A.

    2011-01-01

    The receptivity to freestream acoustic disturbances and the stability properties of hypersonic boundary layers are numerically investigated for boundary-layer flows over a 5 straight cone at a freestream Mach number of 6.0. To compute the shock and the interaction of the shock with the instability waves, the Navier-Stokes equations in axisymmetric coordinates were solved. In the governing equations, inviscid and viscous flux vectors are discretized using a fifth-order accurate weighted-essentially-non-oscillatory scheme. A third-order accurate total-variation-diminishing Runge-Kutta scheme is employed for time integration. After the mean flow field is computed, disturbances are introduced at the upstream end of the computational domain. The appearance of instability waves near the nose region and the receptivity of the boundary layer with respect to slow mode acoustic waves are investigated. Computations confirm the stabilizing effect of nose bluntness and the role of the entropy layer in the delay of boundary-layer transition. The current solutions, compared with experimental observations and other computational results, exhibit good agreement.

  3. Analysis of reflex modulation with a biologically realistic neural network.

    PubMed

    Stienen, Arno H A; Schouten, Alfred C; Schuurmans, Jasper; van der Helm, Frans C T

    2007-12-01

    In this study, a neuromusculoskeletal model was built to give insight into the mechanisms behind the modulation of reflexive feedback strength as experimentally identified in the human shoulder joint. The model is an integration of a biologically realistic neural network consisting of motoneurons and interneurons, modeling 12 populations of spinal neurons, and a one degree-of-freedom musculoskeletal model, including proprioceptors. The model could mimic the findings of human postural experiments, using presynaptic inhibition of the Ia afferents to modulate the feedback gains. In a pathological case, disabling one specific neural connection between the inhibitory interneurons and the motoneurons could mimic the experimental findings in complex regional pain syndrome patients. It is concluded that the model is a valuable tool to gain insight into the spinal contributions to human motor control. Applications lay in the fields of human motor control and neurological disorders, where hypotheses on motor dysfunction can be tested, like spasticity, clonus, and tremor.

  4. Enhanced magnetic ionization in hydrogen reflex discharge plasma source

    SciTech Connect

    Toader, E.I.; Covlea, V.N.

    2005-03-01

    The effect of enhanced magnetic ionization on the external and internal parameters of a high-density, low pressure reflex plasma source operating in hydrogen is studied. The Langmuir probe method and Druyvesteyn procedure coupled with suitable software are used to measure the internal parameters. The bulk plasma region is free of an electric field and presents a high degree of uniformity. The electron energy distribution function is bi-Maxwellian with a dip/shoulder structure around 5.5 eV, independent of external parameters and radial position. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the electron density n{sub e} is as high as 10{sup 18} m{sup -3}, and the electron temperature T{sub e} is as low as a few tens of an electron volt, for dissipated energy of tens of Watts. The bulk plasma density scales with the dissipated power.

  5. Assessment of Hyperactive Reflexes in Patients with Spinal Cord Injury

    PubMed Central

    Yang, Chung-Yong

    2015-01-01

    Hyperactive reflexes are commonly observed in patients with spinal cord injury (SCI) but there is a lack of convenient and quantitative characterizations. Patellar tendon reflexes were examined in nine SCI patients and ten healthy control subjects by tapping the tendon using a hand-held instrumented hammer at various knee flexion angles, and the tapping force, quadriceps EMG, and knee extension torque were measured to characterize patellar tendon reflexes quantitatively in terms of the tendon reflex gain (Gtr), contraction rate (Rc), and reflex loop time delay (td). It was found that there are significant increases in Gtr and Rc and decrease in td in patients with spinal cord injury as compared to the controls (P < 0.05). This study presented a convenient and quantitative method to evaluate reflex excitability and muscle contraction dynamics. With proper simplifications, it can potentially be used for quantitative diagnosis and outcome evaluations of hyperreflexia in clinical settings. PMID:25654084

  6. The exercise pressor reflex and peripheral artery disease.

    PubMed

    Stone, Audrey J; Kaufman, Marc P

    2015-03-01

    The exercise pressor reflex contributes to increases in cardiovascular and ventilatory function during exercise. These reflexive increases are caused by both mechanical stimulation and metabolic stimulation of group III and IV afferents with endings in contracting skeletal muscle. Patients with peripheral artery disease (PAD) have an augmented exercise pressor reflex. Recently, an animal model of PAD was established which allows further investigation of possible mechanisms involved in this augmented reflex. Earlier studies have identified ASIC3 channels, bradykinin receptors, P2X receptors, endoperoxide receptors, and thromboxane receptors as playing a role in evoking the exercise pressor reflex in healthy rats. This review focuses on recent studies using a rat model of PAD in order to determine possible mechanisms contributing to the exaggerated exercise pressor reflex seen in patients with this disease.

  7. The tripartite origins of the tonic neck reflex: Gesell, Gerstmann, and Magnus.

    PubMed

    Shevell, Michael

    2009-03-01

    The standard neurologic examination of the newborn and infant includes the elicitation of the tonic neck reflex. Normally present, its persistence is suggestive of neurologic dysfunction and a prognostic marker highly suggestive of an adverse outcome. Working in different fields, with different approaches and largely independently, three leaders of early 20th century neurosciences (Rudolf Magnus, Josef Gerstmann, and Arnold Gesell) elaborated different aspects of this primitive reflex. Magnus provided the first description in an animal model utilizing a meticulously prepared decerebrate cat correctly identifying the reflex's reliance on proprioceptors in the neck and processing in the upper cervical segment. Gerstmann first described its occurrence in the setting of neurologic disease, providing a meticulous written description in an early description of the index case of what would later be eponymously designated Gerstmann-Straussler-Scheinker syndrome. Gesell initially described the reflex's fundamental occurrence in normal young infants, highlighting its adaptive role in early development and its persistence as a hallmark of neurologic pathology. PMID:19255413

  8. Reflex Seizures Triggered by Diaper Change in Dravet Syndrome.

    PubMed

    Subki, Ahmed H; Alasmari, Aishah S; Jan, Fadi M; Moria, Feras A; Jan, Mohammed M

    2016-07-01

    Dravet syndrome (DS) is a severe epilepsy syndrome characterized by early onset of multiple types of seizures. We report the first case of reflex seizures triggered by diaper change in a girl at 9 months old and 2 years old with a mutation in the SCN1A gene causing DS. Reflex seizures have been reported in patients with DS provoked by increased body temperature or visual stimulation. The case we report widens the spectrum of triggers causing reflex seizures in children with DS. Cortical hyperexcitability resulting from the genetic defect explains the tendency to experience such reflex seizures.

  9. Taking control of reflexive social attention.

    PubMed

    Ristic, Jelena; Kingstone, Alan

    2005-01-01

    Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also the case that top-down factors may modulate the activation of IT cells. Here we examined behaviorally whether reflexive social orienting is purely automatic or sensitive to top-down modulation. Participants were shown an ambiguous stimulus that could be perceived either as representing EYES or a CAR. In we demonstrated between groups that an automatic shift of attention, equivalent to that triggered by a schematic FACE, occurred only when the stimulus was referred to as possessing EYES. In all participants received the EYES and CAR conditions. When the stimulus was first referred to as a CAR and then as EYES, an attentional shift was only present for the EYES condition. However, when the stimulus was first referred to as possessing EYES, and then later as a CAR, attentional shifts were observed for both conditions. These data indicate that the emergence of a reflexive social attention effect is influenced by top-down mechanisms but in an asymmetrical manner. Top-down processes appear to be effective for triggering IT involvement, that is, for perceiving a stimulus as a face, which produces the social attention effect. But top-down mechanisms are ineffective once IT involvement has been triggered. That is, once a stimulus has been seen as having eyes, it continues to be seen that way, and accordingly, the social attention effect persists. PMID:15617667

  10. Methodological Reflexivity: Towards Evolving Methodological Frameworks through Critical and Reflexive Deliberations

    ERIC Educational Resources Information Center

    Raven, Glenda

    2006-01-01

    In this article, the author argues for a central and critical role for "reflexivity in research" with the aim of developing and strengthening not only everyone's understanding of what everyone does in environmental education research, but also how, and why everyone does it. In a narrative account of methodological issues that occurred within, and…

  11. Personal suicidality in reception and identification with suicidal film characters.

    PubMed

    Till, Benedikt; Vitouch, Peter; Herberth, Arno; Sonneck, Gernot; Niederkrotenthaler, Thomas

    2013-04-01

    The authors investigated the impact of suicidality on identity work during film exposure. Adults with low suicidality (n = 150) watched either It's My Party or The Fire Within, censored versions of these films not depicting the suicide, or the control film that concluded with a non-suicidal death. Baseline suicidality was measured with questionnaires before the movie. Identity work and identification with the protagonist were measured after the movie. Suicidality was directly associated with identity work during film dramas depicting suicide methods. The reception of suicide-related media content seems to partially depend on personal suicidality. Potential implications for suicide prevention are discussed.

  12. Reception of the stethoscope and Laënnec's book.

    PubMed Central

    Bishop, P J

    1981-01-01

    A study of contemporary book reviews and other notices enables us to trace the reception of the stethoscope and Laënnec's book between 1816 and 1826. It is quite clear from these that the stethoscope was welcomed with enthusiasm by most people who saw it as the first major diagnostic tool medicine had ever had. Laënnec's book was recognised as being the most important, interesting, accurate, and complete work on diseases of the chest that had ever been published. PMID:7031968

  13. First direct exposure to lunar material for Crew Reception personnel

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The first direct exposure to lunar material for Crew Reception personnel probably happened late Friday, July 25, 1969. Terry Slezak (displaying moon dust on his left hand fingers), Manned Spacecraft Center (MSC) photographic technician, was removing film magazines from the first of two containers when the incident occurred. As he removed the plastic seal from Magazine S, one of the 70mm magazines taken during Apollo 11 Extravehicular Activity (EVA), it was apparent that the exterior of the cassette displayed traces of a black powdery substance. Apollo 11 Commander Neil Armstrong reported during the mission that he had retrieved a 70mm cassette which had dropped to the lunar surface.

  14. Behavior Of Costas Loop In Reception Of Telemetry

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien M.

    1991-01-01

    Report presents theoretical study of behavior of Costas loop in reception of radio carrier signal modulated in phase by sinusoidal or square-wave subcarrier, further modulated in phase by nonreturn-to-zero binary data signal. Phase and frequency of received signal affected by Doppler shift, and instantaneous amplitude of received signal corrupted by additive white Gaussian noise. Signals of this type ordinarily used in spacecraft telemetry, sine-wave subcarrier being preferred for shorter signal paths and square-wave subcarrier for longer signal paths.

  15. Behavior Of Costas Loop In Reception Of Telemetry

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien Manh

    1992-01-01

    Report presents study of behavior of Costas loop in reception of binary non-return-to-zero telemetry signal phase-shift-modulated onto sinusoidal or square-wave subcarrier signal in turn phase-modulated onto carrier signal. Equations describe degradation of performance of Costas loop in terms of phase jitter, conditions causing loss of lock, and other effects. Costas loop used to track telemetry signal with residual carrier in presence of Doppler shift. Performance optimized by suitable choice of bit rate, waveform and frequency of subcarrier, and noise bandwidth of filters in arms of Costas loop.

  16. Dysphoric milk ejection reflex: A case report

    PubMed Central

    2011-01-01

    Dysphoric Milk Ejection Reflex (D-MER) is an abrupt emotional "drop" that occurs in some women just before milk release and continues for not more than a few minutes. The brief negative feelings range in severity from wistfulness to self-loathing, and appear to have a physiological cause. The authors suggest that an abrupt drop in dopamine may occur when milk release is triggered, resulting in a real or relative brief dopamine deficit for affected women. Clinicians can support women with D-MER in several ways; often, simply knowing that it is a recognized phenomenon makes the condition tolerable. Further study is needed. PMID:21645333

  17. Multi-MA reflex triode research.

    SciTech Connect

    Swanekamp, Stephen Brian; Commisso, Robert J.; Weber, Bruce V.; Riordan, John C.; Allen, Raymond J.; Goyer, John R.; Murphy, Donald P.; Mikkelson, Kenneth A.; Harper-Slaboszewicz, Victor Jozef

    2010-08-01

    The Reflex Triode can efficiently produce and transmit medium energy (10-100 keV) x-rays. Perfect reflexing through thin converter can increase transmission of 10-100 keV x-rays. Gamble II experiment at 1 MV, 1 MA, 60 ns - maximum dose with 25 micron tantalum. Electron orbits depend on the foil thickness. Electron orbits from LSP used to calculate path length inside tantalum. A simple formula predicts the optimum foil thickness for reflexing converters. The I(V) characteristics of the diode can be understood using simple models. Critical current dominates high voltage triodes, bipolar current is more important at low voltage. Higher current (2.5 MA), lower voltage (250 kV) triodes are being tested on Saturn at Sandia. Small, precise, anode-cathode gaps enable low impedance operation. Sample Saturn results at 2.5 MA, 250 kV. Saturn dose rate could be about two times greater. Cylindrical triode may improve x-ray transmission. Cylindrical triode design will be tested at 1/2 scale on Gamble II. For higher current on Saturn, could use two cylindrical triodes in parallel. 3 triodes in parallel require positive polarity operation. 'Triodes in series' would improve matching low impedance triodes to generator. Conclusions of this presentation are: (1) Physics of reflex triodes from Gamble II experiments (1 MA, 1 MV) - (a) Converter thickness 1/20 of CSDA range optimizes x-ray dose; (b) Simple model based on electron orbits predicts optimum thickness from LSP/ITS calculations and experiment; (c) I(V) analysis: beam dynamics different between 1 MV and 250 kV; (2) Multi-MA triode experiments on Saturn (2.5 MA, 250 kV) - (a) Polarity inversion in vacuum, (b) No-convolute configuration, accurate gap settings, (c) About half of current produces useful x-rays, (d) Cylindrical triode one option to increase x-ray transmission; and (3) Potential to increase Saturn current toward 10 MA, maintaining voltage and outer diameter - (a) 2 (or 3) cylindrical triodes in parallel, (b) Triodes

  18. Superposition of H reflexes on steady contractions in man.

    PubMed Central

    Rüegg, D G; Krauer, R; Drews, H

    1990-01-01

    1. The aim of the investigation was to study the influence of steady isometric contractions on H reflexes of human soleus muscle. 2. Stimulating and recording conditions were hardly affected by plantar flexions which subjects maintained in a force matching task. 3. If the interval between a preceding control and the test stimulus was less than 8 s the test H reflex was depressed in the relaxed subject. The depression was diminished or removed if the test reflex was superimposed on a background activity. The interval between control and test H reflex was at least 8 s in the following experiments. 4. H reflexes were nearly independent of steady plantar flexions on which they were superimposed. In some subjects, there was a slight increase with increasing torque. During dorsal flexions, H reflexes in all subjects were inhibited with increasing torque. 5. The relationship between test H reflexes, control H reflexes and background activity was evaluated by varying pseudo-randomly stimulus intensity and steady flexion torque. The surface defined by this three-dimensional relation approximated a plane suggesting linear properties of the H reflex. In some subjects threshold intensity decreased slightly with torque, in others it was constant. 6. In response to a warning signal, human subjects initiated steady plantar or dorsal flexions in both feet and, at the same time, they started to concentrate on a light at the onset of which they performed a unilateral ballistic plantar contraction as fast as possible. The relations between H reflex and maintained flexion force during the warning period of the reaction time task were identical to those during force matching, showing that the behavioural context did not modulate the relations. 7. The relations were also the same if reflexes were evoked bi- or unilaterally, illustrating the absence of a mutual modification of simultaneously evoked H reflexes. 8. The relation was the same with ipsilateral matching and relaxed

  19. Wh-filler-gap dependency formation guides reflexive antecedent search

    PubMed Central

    Frazier, Michael; Ackerman, Lauren; Baumann, Peter; Potter, David; Yoshida, Masaya

    2015-01-01

    Prior studies on online sentence processing have shown that the parser can resolve non-local dependencies rapidly and accurately. This study investigates the interaction between the processing of two such non-local dependencies: wh-filler-gap dependencies (WhFGD) and reflexive-antecedent dependencies. We show that reflexive-antecedent dependency resolution is sensitive to the presence of a WhFGD, and argue that the filler-gap dependency established by WhFGD resolution is selected online as the antecedent of a reflexive dependency. We investigate the processing of constructions like (1), where two NPs might be possible antecedents for the reflexive, namely which cowgirl and Mary. Even though Mary is linearly closer to the reflexive, the only grammatically licit antecedent for the reflexive is the more distant wh-NP, which cowgirl. (1). Which cowgirl did Mary expect to have injured herself due to negligence? Four eye-tracking text-reading experiments were conducted on examples like (1), differing in whether the embedded clause was non-finite (1 and 3) or finite (2 and 4), and in whether the tail of the wh-dependency intervened between the reflexive and its closest overt antecedent (1 and 2) or the wh-dependency was associated with a position earlier in the sentence (3 and 4). The results of Experiments 1 and 2 indicate the parser accesses the result of WhFGD formation during reflexive antecedent search. The resolution of a wh-dependency alters the representation that reflexive antecedent search operates over, allowing the grammatical but linearly distant antecedent to be accessed rapidly. In the absence of a long-distance WhFGD (Experiments 3 and 4), wh-NPs were not found to impact reading times of the reflexive, indicating that the parser's ability to select distant wh-NPs as reflexive antecedents crucially involves syntactic structure. PMID:26500579

  20. Disturbed Paraspinal Reflex Following Prolonged Flexion-Relaxation and Recovery

    PubMed Central

    Rogers, Ellen L.; Granata, Kevin P.

    2006-01-01

    Study Design. Repeated measures experimental study of the effect of flexion-relaxation, recovery, and gender on paraspinal reflex dynamics. Objective. To determine the effect of prolonged flexion-relaxation and recovery time on reflex behavior in human subjects. Summary of Background Data. Prolonged spinal flexion has been shown to disturb the paraspinal reflex activity in both animals and human beings. Laxity in passive tissues of the spine from flexion strain may contribute to desensitization of mechanoreceptors. Animal studies indicate that recovery of reflexes may take up to several hours. Little is known about human paraspinal reflex behavior following flexion tasks or the recovery of reflex behavior following the flexion tasks. Methods. A total of 25 subjects performed static flexionrelaxation tasks. Paraspinal muscle reflexes were recorded before and immediately after flexion-relaxation and after a recovery period. Reflexes were quantified from systems identification analyses of electromyographic response in relation to pseudorandom force disturbances applied to the trunk. Results. Trunk angle measured during flexion-relaxation postures was significantly higher following static flexion-relaxation tasks (P < 0.001), indicating creep deformation of passive supporting structures in the trunk. Reflex response was diminished following flexion-relaxation (P < 0.029) and failed to recover to baseline levels during 16 minutes of recovery. Conclusion. Reduced reflex may indicate that the spine is less stable following prolonged flexion-relaxation and, therefore, susceptible to injury. The absence of recovery in reflex after a substantial time indicates that increased low back pain risk from flexion-relaxation may persist after the end of the flexion task. PMID:16582860

  1. Comparison of the main sequence of reflexive saccades and the quick phases of optokinetic nystagmus

    PubMed Central

    Garbutt, S.; Harwood, M.; Harris, C.

    2001-01-01

    BACKGROUND/AIMS—Abnormalities in the saccadic main sequence are an important finding and may indicate pathology of the ocular motor periphery or central neurological disorders. In young or uncooperative patients it can be difficult eliciting a sufficient number of saccades to measure the main sequence. It is often assumed that the quick phases of optokinetic nystagmus (OKN) are identical to saccades. If this were the case, it would be feasible to use OKN, an involuntary response that is easily evoked, as a simple way of eliciting many saccades. The aim of this study was to determine whether reflexive saccades and the quick phases of OKN are indeed identical, and whether OKN quick phases could have a clinical role in identifying patients with slow saccades.
METHODS—OKN and reflexive saccades were recorded from 10 healthy adults using an infrared limbus eye tracker and bitemporal DC electro-oculography simultaneously. OKN was stimulated by rotating a full field patterned curtain around the subject at 10-50°/s. Reflexive saccades were elicited to red LED targets at 5-20° eccentricity.
RESULTS—OKN quick phases tended to have a longer duration compared to saccades, but these differences were not significant. OKN quick phases had a slightly lower peak velocity compared to saccades, which was statistically significant (p<0.05).
CONCLUSION—The main sequence for duration is the same for reflexive saccades and OKN quick phases. The main sequence for peak velocity is slightly faster for reflexive saccades than OKN quick phases, but the difference is unlikely to be of clinical significance. As an illustration of the potential of this technique, the authors demonstrate that OKN quick phases show similar slowness to saccades in a child with brainstem pathology caused by Gaucher disease type III. It is concluded that recording OKN may be a simple clinical means for approximating the main sequence.

 PMID:11734524

  2. Context-Specific Adaptation of Gravity-Dependent Vestibular Reflex Responses

    NASA Technical Reports Server (NTRS)

    Shelhamer, Mark J.

    1999-01-01

    Stabilization of the eyes and head during body movements is important for maintaining balance and keeping the images of objects stationary on our retinas. Impairment of this ability can lead to disorientation and reduced performance in sensorimotor tasks such as piloting of spacecraft. In the absence of a normal earth gravity field, the dynamics of head stabilization, and the interpretation of vestibular signals that sense gravity and linear acceleration, are subject to change. Transitions between different gravitoinertial force environments - as during different phases of space flight - provide an extreme test of the adaptive mechanisms that maintain these reflexive abilities. It is vitally important to determine human adaptive capabilities in such a circumstance, so that we can know to what extent the sensorimotor skills acquired in one gravity environment will transfer to others. Our work lays the foundation for understanding these capabilities, and for determining how we can aid the processes of adaptation and readaptation. An integrated set of experiments addresses this issue. We use the general approach of adapting some type of reflexive eye movement (saccades, the angular vestibulo-ocular reflex (AVOR), the linear vestibulo-ocular reflex (LVOR)), or the vestibulo-collic reflex (VCR), to a particular change in gain or phase in one condition of gravitoiner-tial force, and adapting to a different gain or phase (or asking for no change) in a second gravitoinertial force condition, and then seeing if the gravitoinertial force itself - the context cue - can recall the previously learned adapted responses. The majority of the experiments in the laboratory use the direction of vertical gaze or the direction of gravity (head tilt) as the context cue. This allows us to study context-specificity in a ground-based setting. One set of experiments, to be performed in parabolic flight, specifically uses the magnitude of gravitoinertial force as a context cue. This is a

  3. Approaching sign language test construction: adaptation of the German sign language receptive skills test.

    PubMed

    Haug, Tobias

    2011-01-01

    There is a current need for reliable and valid test instruments in different countries in order to monitor deaf children's sign language acquisition. However, very few tests are commercially available that offer strong evidence for their psychometric properties. A German Sign Language (DGS) test focusing on linguistic structures that are acquired in preschool- and school-aged children (4-8 years old) is urgently needed. Using the British Sign Language Receptive Skills Test, that has been standardized and has sound psychometric properties, as a template for adaptation thus provides a starting point for tests of a sign language that is less documented, such as DGS. This article makes a novel contribution to the field by examining linguistic, cultural, and methodological issues in the process of adapting a test from the source language to the target language. The adapted DGS test has sound psychometric properties and provides the basis for revision prior to standardization. PMID:21208998

  4. Approaching sign language test construction: adaptation of the German sign language receptive skills test.

    PubMed

    Haug, Tobias

    2011-01-01

    There is a current need for reliable and valid test instruments in different countries in order to monitor deaf children's sign language acquisition. However, very few tests are commercially available that offer strong evidence for their psychometric properties. A German Sign Language (DGS) test focusing on linguistic structures that are acquired in preschool- and school-aged children (4-8 years old) is urgently needed. Using the British Sign Language Receptive Skills Test, that has been standardized and has sound psychometric properties, as a template for adaptation thus provides a starting point for tests of a sign language that is less documented, such as DGS. This article makes a novel contribution to the field by examining linguistic, cultural, and methodological issues in the process of adapting a test from the source language to the target language. The adapted DGS test has sound psychometric properties and provides the basis for revision prior to standardization.

  5. 33 CFR 157.304 - Shore-based reception facility: standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Shore-based reception facility... CARRYING OIL IN BULK Exemption From § 157.10a or § 157.10c § 157.304 Shore-based reception facility: standards. No shore-based reception facility may be listed to meet § 157.302(b)(3) unless that...

  6. Metabolic syndrome and the hepatorenal reflex.

    PubMed

    Wider, Michael D

    2016-01-01

    Insufficient hepatic O2 in animal and human studies has been shown to elicit a hepatorenal reflex in response to increased hepatic adenosine, resulting in stimulation of renal as well as muscle sympathetic nerve activity and activating the renin angiotensin system. Low hepatic ATP, hyperuricemia, and hepatic lipid accumulation reported in metabolic syndrome (MetS) patients may reflect insufficient hepatic O2 delivery, potentially accounting for the sympathetic overdrive associated with MetS. This theoretical concept is supported by experimental results in animals fed a high fructose diet to induce MetS. Hepatic fructose metabolism rapidly consumes ATP resulting in increased adenosine production and hyperuricemia as well as elevated renin release and sympathetic activity. This review makes the case for the hepatorenal reflex causing sympathetic overdrive and metabolic syndrome in response to exaggerated splanchnic oxygen consumption from excessive eating. This is strongly reinforced by the fact that MetS is cured in a matter of days in a significant percentage of patients by diet, bariatric surgery, or endoluminal sleeve, all of which would decrease splanchnic oxygen demand by limiting nutrient contact with the mucosa and reducing the nutrient load due to the loss of appetite or dietary restriction. PMID:27656314

  7. Metabolic syndrome and the hepatorenal reflex

    PubMed Central

    Wider, Michael D.

    2016-01-01

    Insufficient hepatic O2 in animal and human studies has been shown to elicit a hepatorenal reflex in response to increased hepatic adenosine, resulting in stimulation of renal as well as muscle sympathetic nerve activity and activating the renin angiotensin system. Low hepatic ATP, hyperuricemia, and hepatic lipid accumulation reported in metabolic syndrome (MetS) patients may reflect insufficient hepatic O2 delivery, potentially accounting for the sympathetic overdrive associated with MetS. This theoretical concept is supported by experimental results in animals fed a high fructose diet to induce MetS. Hepatic fructose metabolism rapidly consumes ATP resulting in increased adenosine production and hyperuricemia as well as elevated renin release and sympathetic activity. This review makes the case for the hepatorenal reflex causing sympathetic overdrive and metabolic syndrome in response to exaggerated splanchnic oxygen consumption from excessive eating. This is strongly reinforced by the fact that MetS is cured in a matter of days in a significant percentage of patients by diet, bariatric surgery, or endoluminal sleeve, all of which would decrease splanchnic oxygen demand by limiting nutrient contact with the mucosa and reducing the nutrient load due to the loss of appetite or dietary restriction. PMID:27656314

  8. Airway reflexes, autonomic function, and cardiovascular responses.

    PubMed Central

    Widdicombe, J; Lee, L Y

    2001-01-01

    In this article, we review the cardiovascular responses to the inhalation of irritants and pollutants. Many sensory receptors in the respiratory system, from nose to alveoli, respond to these irritants and set up powerful reflex changes, including those in the cardiovascular system. Systemic hypotension or hypertension, pulmonary hypertension, bradycardia, tachycardia, and dysrhythmias have all been described previously. Most of the experiments have been acute and have been performed on anesthetized experimental animals. Experiments on humans suggest we have similar sensory systems and reflex responses. However, we must use caution when applying the animal results to humans. Most animal experiments, unlike those with humans, have been performed using general anesthesia, with irritants administered in high concentrations, and often to a restricted part of the respiratory tract. Species differences in the response to irritants are well established. We must be even more careful when applying the results of acute experiments in animals to the pathophysiologic changes observed in prolonged exposure to environmental pollution in humans. PMID:11544167

  9. Cough reflex sensitization from esophagus and nose.

    PubMed

    Hennel, Michal; Brozmanova, Mariana; Kollarik, Marian

    2015-12-01

    The diseases of the esophagus and nose are among the major factors contributing to chronic cough although their role in different patient populations is debated. Studies in animal models and in humans show that afferent C-fiber activators applied on esophageal or nasal mucosa do not initiate cough, but enhance cough induced by inhaled irritants. These results are consistent with the hypothesis that activation of esophageal and nasal C-fibers contribute to cough reflex hypersensitivity observed in chronic cough patients with gastroesophageal reflux disease (GERD) and chronic rhinitis, respectively. The afferent nerves mediating cough sensitization from the esophagus are probably the neural crest-derived vagal jugular C-fibers. In addition to their responsiveness to high concentration of acid typical for gastroesophageal reflux (pH < 5), esophageal C-fibers also express receptors for activation by weakly acidic reflux such as receptors highly sensitive to acid and receptors for bile acids. The nature of sensory pathways from the nose and their activators relevant for cough sensitization are less understood. Increased cough reflex sensitivity was also reported in many patients with GERD or rhinitis who do not complain of cough indicating that additional endogenous or exogenous factors may be required to develop chronic coughing in these diseases.

  10. Metabolic syndrome and the hepatorenal reflex

    PubMed Central

    Wider, Michael D.

    2016-01-01

    Insufficient hepatic O2 in animal and human studies has been shown to elicit a hepatorenal reflex in response to increased hepatic adenosine, resulting in stimulation of renal as well as muscle sympathetic nerve activity and activating the renin angiotensin system. Low hepatic ATP, hyperuricemia, and hepatic lipid accumulation reported in metabolic syndrome (MetS) patients may reflect insufficient hepatic O2 delivery, potentially accounting for the sympathetic overdrive associated with MetS. This theoretical concept is supported by experimental results in animals fed a high fructose diet to induce MetS. Hepatic fructose metabolism rapidly consumes ATP resulting in increased adenosine production and hyperuricemia as well as elevated renin release and sympathetic activity. This review makes the case for the hepatorenal reflex causing sympathetic overdrive and metabolic syndrome in response to exaggerated splanchnic oxygen consumption from excessive eating. This is strongly reinforced by the fact that MetS is cured in a matter of days in a significant percentage of patients by diet, bariatric surgery, or endoluminal sleeve, all of which would decrease splanchnic oxygen demand by limiting nutrient contact with the mucosa and reducing the nutrient load due to the loss of appetite or dietary restriction.

  11. Reflex control of the circulation during exercise.

    PubMed

    Fadel, P J

    2015-12-01

    Appropriate cardiovascular and hemodynamic adjustments are necessary to meet the metabolic demands of working skeletal muscle during exercise. Alterations in the sympathetic and parasympathetic branches of the autonomic nervous system are fundamental in ensuring these adjustments are adequately made. Several neural mechanisms are responsible for the changes in autonomic activity with exercise and through complex interactions, contribute to the cardiovascular and hemodynamic changes in an intensity-dependent manner. This short review is from a presentation made at the Saltin Symposium June 2-4, 2015 in Copenhagen, Denmark. As such, the focus will be on reflex control of the circulation with an emphasis on the work of the late Dr. Bengt Saltin. Moreover, a concerted effort is made to highlight the novel and insightful concepts put forth by Dr. Saltin in his last published review article on the regulation of skeletal muscle blood flow in humans. Thus, the multiple roles played by adenosine triphosphate (ATP) including its ability to induce vasodilatation, override sympathetic vasoconstriction and stimulate skeletal muscle afferents (exercise pressor reflex) are discussed and a conceptual framework is set suggesting a major role of ATP in blood flow regulation during exercise.

  12. The history and reception of Charles Darwin's hypothesis of pangenesis.

    PubMed

    Holterhoff, Kate

    2014-01-01

    This paper explores Charles Darwin's hypothesis of pangenesis through a popular and professional reception history. First published in The Variation of Animals and Plants under Domestication (1868), pangenesis stated that inheritance can be explained by sub-cellular "gemmules" which aggregated in the sexual organs during intercourse. Pangenesis thereby accounted for the seemingly arbitrary absence and presence of traits in offspring while also clarifying some botanical and invertebrates' limb regeneration abilities. I argue that critics largely interpreted Variation as an extension of On the Origin of Species by Means of Natural Selection (1859), while pangenesis was an extension of natural selection. Contrary to claims that pangenesis was divorced from natural selection by its reliance on the inheritance of acquired characters, pangenesis's mid nineteenth-century reception suggests that Darwin's hypothesis responded directly to selection's critics. Using Variation's several editions, periodical reviews, and personal correspondence I assess pangenesis popularly, professionally, and biographically to better understand Variation's impact on 1860s and 70s British evolutionism and inheritance. PMID:24570302

  13. Mach's phenomenalism and the British reception of Mendelism.

    PubMed

    Sloan, P R

    2000-12-01

    The assimilation of Mendel's paper into Britain took place in an Edwardian social context. This paper concentrates on the interplay of empirical and philosophical issues in this reception. A feature of the British reception of mendelism, not duplicated elsewhere, was the role of phenomenalist philosophies of science as developed by the physicist-mathematician and scientific methodologist Karl Pearson from the philosophical positions of Austrian physicist Ernst Mach and British mathematician William Clifford. Pearson's philosophy of science forms the background to his subsequent collaboration with the zoologist W.F.R. Weldon. In this collaborative work, Pearson developed powerful statistical techniques for analyzing Weldon's empirical data on organic variation. Pearson's statistical analysis of causation and his rejection of hidden entities and causes in the explanation of evolutionary change formed the philosophical component of this program. The arguments of Pearson and Weldon were first brought to bear against the pre-Mendel 'discontinuist' analyses of variation of William Bateson. The introduction of Mendel's paper into these empirical and methodological debates consequently resulted in mathematically sophisticated attacks on Mendel's claims by Pearson and Weldon. This paper summarizes this history and argues for the creative importance of this biometrical resistance to Mendelism. PMID:11147093

  14. On the receptive prosodic loss in Parkinson's disease.

    PubMed

    Pell, M D

    1996-12-01

    To comprehensively explore how the processing of linguistic and affective prosodic cues is affected by idiopathic Parkinson's disease (PD), a battery of receptive tests was presented to eleven PD patients without intellectual or language impairment and eleven control subjects (NC) matched for age, gender, and educational attainment. Receptive abilities for both low-level (discrimination) and higher-level (identification) prosodic processing were explored; moreover, the identification of prosodic feature was tested at both the lexical level (phonemic stress perception) and over the sentential domain (prosodic pattern identification). The results obtained demonstrated a general reduction in the ability of the PD patients to identify the linguistic- and affective-prosodic meaning of utterances relative to NC subjects, without a concurrent loss in the ability to perceive phonemic stress contrasts or discriminate prosodic patterns. However, the qualitative pattern of the PD and NC groups' performance across the various identification conditions tested was remarkably uniform, indicating that only quantitative differences in comprehension abilities may have characterized the two groups. It is hypothesized that the basal ganglia form part of a functional network dedicated to prosodic processing (Blonder et al., 1989) and that the processes required to map prosodic features onto their communicative representations at the sentence level are rendered less efficient by the degenerative course of PD. PMID:8954247

  15. The history and reception of Charles Darwin's hypothesis of pangenesis.

    PubMed

    Holterhoff, Kate

    2014-01-01

    This paper explores Charles Darwin's hypothesis of pangenesis through a popular and professional reception history. First published in The Variation of Animals and Plants under Domestication (1868), pangenesis stated that inheritance can be explained by sub-cellular "gemmules" which aggregated in the sexual organs during intercourse. Pangenesis thereby accounted for the seemingly arbitrary absence and presence of traits in offspring while also clarifying some botanical and invertebrates' limb regeneration abilities. I argue that critics largely interpreted Variation as an extension of On the Origin of Species by Means of Natural Selection (1859), while pangenesis was an extension of natural selection. Contrary to claims that pangenesis was divorced from natural selection by its reliance on the inheritance of acquired characters, pangenesis's mid nineteenth-century reception suggests that Darwin's hypothesis responded directly to selection's critics. Using Variation's several editions, periodical reviews, and personal correspondence I assess pangenesis popularly, professionally, and biographically to better understand Variation's impact on 1860s and 70s British evolutionism and inheritance.

  16. Receptivity to thermal noise in real airfoil configurations

    NASA Astrophysics Data System (ADS)

    Luchini, Paolo

    2014-11-01

    Thermal noise, the macroscopic manifestation of microscopic particle agitation, is present in fluid flow just as in electron flow in conductors or in other physical transport phenomena. When the flow acts as an amplifier, typically during transition to turbulence, the transition position can be influenced by the amplitude of external disturbances through the so called receptivity of the flow instabilities; internally generated thermal noise represents a thermodynamically enforced lower bound to how much disturbances can be reduced. In a previous paper (Seventh IUTAM Symposium on Laminar-Turbulent Transition, IUTAM Bookseries Volume 18, Springer, 2010, pp. 11-18), the present author showed that the maximum transition distance in a Blasius boundary layer corresponds to a Reynolds number little above 6 .106 and to an N-factor of the order of 13. Results to be exhibited at this conference show that in a real airfoil configuration the maximum transition Reynolds number imposed by thermal noise is even lower than on a flat wall, and not far from the actually observed transition position. It follows that thermal noise might actually have a role in natural transition; and that even a perfectly silenced laboratory environment cannot push the transition position much farther. Work supported by the European Community through the RECEPT grant.

  17. Implantation in assisted reproduction: a look at endometrial receptivity.

    PubMed

    Fatemi, H M; Popovic-Todorovic, B

    2013-11-01

    Implantation failure in assisted reproduction is thought to be mainly due to impaired uterine receptivity. With normal uterine anatomy, changes in endocrine profile during ovarian stimulation and medical conditions of the mother (i.e. thrombophilia and abnormal immunological response) could result in a non-receptive endometrium. High oestradiol concentrations during ovarian stimulation lead to premature progesterone elevation, causing endometrial advancement and hampering implantation, which can be overcome by a freeze-all approach and embryo transfer in natural cycles or by milder stimulation protocols. Patients with recurrent implantation failure (RIF) should be tested for inherited and acquired thrombophilias. Each patient should be individually assessed and counselled regarding therapy with low-molecular-weight heparin (LMWH). Empirical treatment with LMWH, aspirin or corticosteroids is not effective for women with RIF who have negative thrombophilic tests. If thrombophilic tests are normal, patients should be tested for immunological causes. If human leukocyte antigen dissimilarity is proven, treatment with intravenous immunoglobulin might be beneficial. Preliminary observational studies using intralipid infusion in the presence of increased natural killer cytotoxic activity are interesting but the proposed rationale is controversial and randomized controlled trials are needed. Hysteroscopy and/or endometrial scratching in the cycle preceding ovarian stimulation should become standard for patients with RIF.

  18. Reflexivity in Teams: A Review and New Perspectives.

    PubMed

    Konradt, Udo; Otte, Kai-Philip; Schippers, Michaéla C; Steenfatt, Corinna

    2016-01-01

    Team reflexivity posits that the extent to which teams reflect upon and adapt their functioning is positively related to team performance. While remarkable progress has been made to provide evidence of this relationship, the underlying framework is missing elements of current theoretical streams for analyzing and describing teamwork, leaving the diversity of effects of team reflexivity often untouched. In this article, we present an update for this framework, by reviewing previous research on reflexivity, addressing gaps in the literature, and revising the original model by integrating feedback and dynamic team effectiveness frameworks for describing temporal developments of reflexivity. We furthermore propose a new dimensional structure for reflexivity, relying on prior work conceptualizing teams as information-processing systems that learn and advance through social-cognitive elements. Our model is therefore not only suitable for explaining the diverse set of relationships between team reflexivity on outcomes, but also provides valuable directions for viewing reflexivity as process that takes place during both transition and action phases of teamwork. We conclude with implications for managers, identify limitations, and propose an agenda for further research into this area. This article contributes an extended perspective relevant for further theory development and for effectively managing reflexivity in teams. PMID:26457836

  19. Tendon reflex is suppressed during whole-body vibration.

    PubMed

    Karacan, Ilhan; Cidem, Muharrem; Yilmaz, Gizem; Sebik, Oguz; Cakar, Halil Ibrahim; Türker, Kemal Sıtkı

    2016-10-01

    In this study we have investigated the effect of whole body vibration (WBV) on the tendon reflex (T-reflex) amplitude. Fifteen young adult healthy volunteer males were included in this study. Records of surface EMG of the right soleus muscle and accelerometer taped onto the right Achilles tendon were obtained while participant stood upright with the knees in extension, on the vibration platform. Tendon reflex was elicited before and during WBV. Subjects completed a set of WBV. Each WBV set consisted of six vibration sessions using different frequencies (25, 30, 35, 40, 45, 50Hz) applied randomly. In each WBV session the Achilles tendon was tapped five times with a custom-made reflex hammer. The mean peak-to-peak (PP) amplitude of T-reflex was 1139.11±498.99µV before vibration. It decreased significantly during WBV (p<0.0001). The maximum PP amplitude of T-reflex was 1333±515μV before vibration. It decreased significantly during WBV (p<0.0001). No significant differences were obtained in the mean acceleration values of Achilles tendon with tapping between before and during vibration sessions. This study showed that T-reflex is suppressed during WBV. T-reflex suppression indicates that the spindle primary afferents must have been pre-synaptically inhibited during WBV similar to the findings in high frequency tendon vibration studies. PMID:27485766

  20. Iris Pigmentation and Fractionated Reaction and Reflex Time.

    ERIC Educational Resources Information Center

    Hale, Bruce D.; And Others

    Behavioral measures, fractionated reaction and reflex times by means of electromyography, were used to determine if the eye color differences are found in the central or peripheral regions of the nervous system. The purpose of this research was to determine the truth of the hypothesis that dark-eyed individuals have faster reflex and reaction time…

  1. Ultimate concerns in late modernity: Archer, Bourdieu and reflexivity.

    PubMed

    Farrugia, David; Woodman, Dan

    2015-12-01

    Through a critique of Margaret Archer's theory of reflexivity, this paper explores the theoretical contribution of a Bourdieusian sociology of the subject for understanding social change. Archer's theory of reflexivity holds that conscious 'internal conversations' are the motor of society, central both to human subjectivity and to the 'reflexive imperative' of late modernity. This is established through critiques of Bourdieu, who is held to erase creativity and meaningful personal investments from subjectivity, and late modernity is depicted as a time when a 'situational logic of opportunity' renders embodied dispositions and the reproduction of symbolic advantages obsolete. Maintaining Archer's focus on 'ultimate concerns' in a context of social change, this paper argues that her theory of reflexivity is established through a narrow misreading and rejection of Bourdieu's work, which ultimately creates problems for her own approach. Archer's rejection of any pre-reflexive dimensions to subjectivity and social action leaves her unable to sociologically explain the genesis of 'ultimate concerns', and creates an empirically dubious narrative of the consequences of social change. Through a focus on Archer's concept of 'fractured reflexivity', the paper explores the theoretical necessity of habitus and illusio for understanding the social changes that Archer is grappling with. In late modernity, reflexivity is valorized just as the conditions for its successful operation are increasingly foreclosed, creating 'fractured reflexivity' emblematic of the complex contemporary interaction between habitus, illusio, and accelerating social change.

  2. [The development of I. P. Pavlov's conditioned reflex theory].

    PubMed

    Kim, O J

    1992-01-01

    This paper deals with the theory of Ivan Petrovich Pavlov (1849-1936), a Russian physiologist who presented for the first time the systematic theory of the function of the brain that controls the whole behavior of animals, i.e. higher nervous activity through experimental studies. This paper, principally based on Lectures on Conditioned Reflexes (1928), investigates the development of conditioned reflex theory from its beginning by dividing it into three periods. First, during the period from 1898 to 1906, the fundamental concept of conditioned reflex was established and the study of conditioned reflex became an independent discipline. From 1907 to 1916, the second period, Pavlov theorized on higher nervous activity on the basis of extensive data from his laboratory experiments of conditioned reflex. And Pavlov complemented conditioned reflex theory, during the third period from 1916 to 1928, and extended the boundaries of it through applications of conditioned reflex theory to psychopathology and typology. The study contributes to the understanding that conditioned reflex theory was historically developed, and not presented as a complete form from the beginning, and that Pavlov intended to study the higher nervous activity through the method of neurophysiology.

  3. [Value of blink reflex studies in neurosurgical problems].

    PubMed

    Jamjoom, Z; Nahser, H C; Nau, H E

    1983-09-01

    Blinking reflex studies were done in neurosurgical patients with processes in the posterior fossa and idiopathic trigeminal neuralgia. Alterations were found in space occupying, ischemic, and traumatic lesions of the trigemino-facial system. The analysis of the components of the blinking reflex can give hints to the site of the lesion and also to the prognosis of the underlying process.

  4. Ultimate concerns in late modernity: Archer, Bourdieu and reflexivity.

    PubMed

    Farrugia, David; Woodman, Dan

    2015-12-01

    Through a critique of Margaret Archer's theory of reflexivity, this paper explores the theoretical contribution of a Bourdieusian sociology of the subject for understanding social change. Archer's theory of reflexivity holds that conscious 'internal conversations' are the motor of society, central both to human subjectivity and to the 'reflexive imperative' of late modernity. This is established through critiques of Bourdieu, who is held to erase creativity and meaningful personal investments from subjectivity, and late modernity is depicted as a time when a 'situational logic of opportunity' renders embodied dispositions and the reproduction of symbolic advantages obsolete. Maintaining Archer's focus on 'ultimate concerns' in a context of social change, this paper argues that her theory of reflexivity is established through a narrow misreading and rejection of Bourdieu's work, which ultimately creates problems for her own approach. Archer's rejection of any pre-reflexive dimensions to subjectivity and social action leaves her unable to sociologically explain the genesis of 'ultimate concerns', and creates an empirically dubious narrative of the consequences of social change. Through a focus on Archer's concept of 'fractured reflexivity', the paper explores the theoretical necessity of habitus and illusio for understanding the social changes that Archer is grappling with. In late modernity, reflexivity is valorized just as the conditions for its successful operation are increasingly foreclosed, creating 'fractured reflexivity' emblematic of the complex contemporary interaction between habitus, illusio, and accelerating social change. PMID:26434655

  5. The proboscis extension reflex not elicited in Magachilid bees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Honey bees (Apis mellifera L.) will reflexively extend their proboscis in response to antennal stimulation with sucrose solution. For decades, the proboscis extension reflex (PER) of honey bees has been used as a tool to further the understanding of their cognitive processes, such as learning and m...

  6. A Movement Account of Long-Distance Reflexives

    ERIC Educational Resources Information Center

    McKeown, Rebecca Katherine

    2013-01-01

    This thesis examines reflexive pronouns, such as Icelandic "sig" (Cf. Thrainsson 2007), which may be bound from outside of an infinitive clause (which I call MD "medium distance" binding) in addition to being bound locally. I propose that such reflexives are linked to their antecedents via sisterhood followed by movement: the…

  7. Reflexivity of Discomfort in Insider-Outsider Educational Research

    ERIC Educational Resources Information Center

    Hamdan, Amani K.

    2009-01-01

    This paper discusses my position as an Arab Muslim woman researcher who is affiliated with a Western university, researching Arab Muslim Canadian women. I discuss how reflexivity has emerged as an element of my research endeavours. Various notions of reflexivity in educational research have been expressed in the literature, yet I focus on what it…

  8. [The development of I. P. Pavlov's conditioned reflex theory].

    PubMed

    Kim, O J

    1992-01-01

    This paper deals with the theory of Ivan Petrovich Pavlov (1849-1936), a Russian physiologist who presented for the first time the systematic theory of the function of the brain that controls the whole behavior of animals, i.e. higher nervous activity through experimental studies. This paper, principally based on Lectures on Conditioned Reflexes (1928), investigates the development of conditioned reflex theory from its beginning by dividing it into three periods. First, during the period from 1898 to 1906, the fundamental concept of conditioned reflex was established and the study of conditioned reflex became an independent discipline. From 1907 to 1916, the second period, Pavlov theorized on higher nervous activity on the basis of extensive data from his laboratory experiments of conditioned reflex. And Pavlov complemented conditioned reflex theory, during the third period from 1916 to 1928, and extended the boundaries of it through applications of conditioned reflex theory to psychopathology and typology. The study contributes to the understanding that conditioned reflex theory was historically developed, and not presented as a complete form from the beginning, and that Pavlov intended to study the higher nervous activity through the method of neurophysiology. PMID:11618531

  9. Reflexivity in Teams: A Review and New Perspectives.

    PubMed

    Konradt, Udo; Otte, Kai-Philip; Schippers, Michaéla C; Steenfatt, Corinna

    2016-01-01

    Team reflexivity posits that the extent to which teams reflect upon and adapt their functioning is positively related to team performance. While remarkable progress has been made to provide evidence of this relationship, the underlying framework is missing elements of current theoretical streams for analyzing and describing teamwork, leaving the diversity of effects of team reflexivity often untouched. In this article, we present an update for this framework, by reviewing previous research on reflexivity, addressing gaps in the literature, and revising the original model by integrating feedback and dynamic team effectiveness frameworks for describing temporal developments of reflexivity. We furthermore propose a new dimensional structure for reflexivity, relying on prior work conceptualizing teams as information-processing systems that learn and advance through social-cognitive elements. Our model is therefore not only suitable for explaining the diverse set of relationships between team reflexivity on outcomes, but also provides valuable directions for viewing reflexivity as process that takes place during both transition and action phases of teamwork. We conclude with implications for managers, identify limitations, and propose an agenda for further research into this area. This article contributes an extended perspective relevant for further theory development and for effectively managing reflexivity in teams.

  10. Tendon reflex is suppressed during whole-body vibration.

    PubMed

    Karacan, Ilhan; Cidem, Muharrem; Yilmaz, Gizem; Sebik, Oguz; Cakar, Halil Ibrahim; Türker, Kemal Sıtkı

    2016-10-01

    In this study we have investigated the effect of whole body vibration (WBV) on the tendon reflex (T-reflex) amplitude. Fifteen young adult healthy volunteer males were included in this study. Records of surface EMG of the right soleus muscle and accelerometer taped onto the right Achilles tendon were obtained while participant stood upright with the knees in extension, on the vibration platform. Tendon reflex was elicited before and during WBV. Subjects completed a set of WBV. Each WBV set consisted of six vibration sessions using different frequencies (25, 30, 35, 40, 45, 50Hz) applied randomly. In each WBV session the Achilles tendon was tapped five times with a custom-made reflex hammer. The mean peak-to-peak (PP) amplitude of T-reflex was 1139.11±498.99µV before vibration. It decreased significantly during WBV (p<0.0001). The maximum PP amplitude of T-reflex was 1333±515μV before vibration. It decreased significantly during WBV (p<0.0001). No significant differences were obtained in the mean acceleration values of Achilles tendon with tapping between before and during vibration sessions. This study showed that T-reflex is suppressed during WBV. T-reflex suppression indicates that the spindle primary afferents must have been pre-synaptically inhibited during WBV similar to the findings in high frequency tendon vibration studies.

  11. Approaches to Reflexivity: Navigating Educational and Career Pathways

    ERIC Educational Resources Information Center

    Dyke, Martin; Johnston, Brenda; Fuller, Alison

    2012-01-01

    This paper provides a critical appraisal of approaches to reflexivity in sociology. It uses data from social network research to argue that Archer's approach to reflexivity provides a valuable lens with which to understand how people navigate their education and career pathways. The paper is also critical of Archer's methodology and typology of…

  12. Reflexive Management Learning: An Integrative Review and a Conceptual Typology

    ERIC Educational Resources Information Center

    Cotter, Richard J.; Cullen, John G.

    2012-01-01

    The scale and reach of the recent global financial has created a fresh wave of interest in exploring more sustainable forms of management. A central thrust behind this trend in the practice of management development and education has been the accentuation of reflexivity. There are many variations in how reflexivity is understood, and this article…

  13. Role of stretch reflex in voluntary movements. [of human foot

    NASA Technical Reports Server (NTRS)

    Gottlieb, G. L.; Agarwal, G. C.

    1975-01-01

    The stretch reflex is often described as a spinal servomechanism, a device for assisting in the regulation of muscle length. Observation of the EMG response to mechanical interruption of voluntary movements fails to demonstrate a significant role for spinal reflexes at 40 msec latency. Two functional responses with latencies of 120 msec and 200 msec, implying supraspinal mediation, are observed.

  14. Airborne Antenna System for Minimum-Cycle-Slip GPS Reception

    NASA Technical Reports Server (NTRS)

    Wright, C. Wayne

    2009-01-01

    A system that includes a Global Positioning System (GPS) antenna and associated apparatus for keeping the antenna aimed upward has been developed for use aboard a remote-sensing-survey airplane. The purpose served by the system is to enable minimum- cycle-slip reception of GPS signals used in precise computation of the trajectory of the airplane, without having to restrict the airplane to maneuvers that increase the flight time needed to perform a survey. Cycle slip signifies loss of continuous track of the phase of a signal. Minimum-cycle-slip reception is desirable because maintaining constant track of the phase of the carrier signal from each available GPS satellite is necessary for surveying to centimeter or subcentimeter precision. Even a loss of signal for as short a time as a nanosecond can cause cycle slip. Cycle slips degrade the quality and precision of survey data acquired during a flight. The two principal causes of cycle slip are weakness of signals and multipath propagation. Heretofore, it has been standard practice to mount a GPS antenna rigidly on top of an airplane, and the radiation pattern of the antenna is typically hemispherical, so that all GPS satellites above the horizon are viewed by the antenna during level flight. When the airplane must be banked for a turn or other maneuver, the reception hemisphere becomes correspondingly tilted; hence, the antenna no longer views satellites that may still be above the Earth horizon but are now below the equatorial plane of the tilted reception hemisphere. Moreover, part of the reception hemisphere (typically, on the inside of a turn) becomes pointed toward ground, with a consequent increase in received noise and, therefore, degradation of GPS measurements. To minimize the likelihood of loss of signal and cycle slip, bank angles of remote-sensing survey airplanes have generally been limited to 10 or less, resulting in skidding or slipping uncoordinated turns. An airplane must be banked in order to make

  15. Parametric exploration of the fear-inhibited light reflex.

    PubMed

    Hourdaki, Eugenia; Giakoumaki, Stella G; Grinakis, Vangelis; Theou, Katerina; Karataraki, Maria; Bitsios, Panos

    2005-07-01

    The effect of various parameters on the mediation of the fear-inhibited light reflex was examined. The light reflexes of 16 healthy men were measured across four light probe intensities, either in the presence of white noise alone or when the white noise was associated with the threat of either an electric shock or an acoustic sound blast. The white noise alone did not affect the light reflex amplitude. Both types of threat were subjectively anxiogenic and inhibited the light reflex across all light probe intensities, the threat of shock being more potent than the threat of sound blast. Importantly, the effect of either type of threat on the light reflex amplitude was found to increase with increasing light probe intensity, suggesting that brighter light probes may become more relevant motivationally in the threat condition, thus attracting greater allocation of attentional/cognitive resources.

  16. Problems Associated with Choice and Quality of Life for an Individual with Intellectual Disability: A Personal Assistant's Reflexive Ethnography

    ERIC Educational Resources Information Center

    Schelly, David

    2008-01-01

    A gap exists between research and practice within the field of intellectual disability. In particular, researchers suggest that personal choice enhances quality of life. Following Bourdieu's suggestion to focus on improving the practice of theory rather than the theory of practice, this paper is a reflexive ethnography detailing my struggles to…

  17. Second-Wave White Teacher Identity Studies: Toward Complexity and Reflexivity in the Racial Conscientization of White Teachers

    ERIC Educational Resources Information Center

    Jupp, James C.; Lensmire, Timothy J.

    2016-01-01

    In this article, we introduce our special issue, "Second-Wave White Teacher Identity Studies: Toward Complexity and Reflexivity in the Racial Conscientization of White Teachers." We characterize white teacher identity studies as a developing field with important implications for education research and teacher education. Early work in…

  18. Reflexivity over and above convention: the new orthodoxy in the sociology of personal life, formerly sociology of the family.

    PubMed

    Gilding, Michael

    2010-12-01

    There is a new orthodoxy in the field that was once understood as the sociology of the family, and is increasingly understood as the sociology of 'personal life', 'intimacy', 'relationships' and 'families'. The orthodoxy highlights the open-endedness of intimate relations at the expense of the family as an institution; that is, reflexivity over and above convention. This article argues that the new orthodoxy not only overstates reflexivity at the expense of convention, but abdicates understanding to frameworks grounded in biologistic and economistic understandings of human behaviour. The article makes its point through attention to three areas of research at odds with the new orthodoxy: paternity uncertainty, inheritance and family business. It then proposes that conceptualization of the family as an institutional regime gives due weight to the reflexive reconfiguration of family relationships and practices on the one hand, and their institutional embeddedness on the other.

  19. The receptive-expressive gap in the vocabulary of young second-language learners: Robustness and possible mechanisms

    PubMed Central

    Gibson, Todd A.; Oller, D. Kimbrough; Jarmulowicz, Linda; Ethington, Corinna A.

    2010-01-01

    Adults and children learning a second language show difficulty accessing expressive vocabulary that appears accessible receptively in their first language (L1). We call this discrepancy the receptive-expressive gap. Kindergarten Spanish (L1) - English (L2) sequential bilinguals were given standardized tests of receptive and expressive vocabulary in both Spanish and English. We found a small receptive-expressive gap in English but a large receptive-expressive gap in Spanish. We categorized children as having had high or low levels of English exposure based on demographic variables and found that the receptive-expressive gap persisted across both levels of English exposure. Regression analyses revealed that variables predicting both receptive and expressive vocabulary scores failed to predict the receptive-expressive gap. The results suggest that the onset of the receptive-expressive gap in L1 must have been abrupt. We discuss possible mechanisms underlying the phenomenon. PMID:22247648

  20. Resuscitation and auto resuscitation by airway reflexes in animals.

    PubMed

    Tomori, Zoltan; Donic, Viliam; Benacka, Roman; Jakus, Jan; Gresova, Sona

    2013-01-01

    Various diseases often result in decompensation requiring resuscitation. In infants moderate hypoxia evokes a compensatory augmented breath - sigh and more severe hypoxia results in a solitary gasp. Progressive asphyxia provokes gasping respiration saving the healthy infant - autoresuscitation by gasping. A neonate with sudden infant death syndrome, however, usually will not survive. Our systematic research in animals indicated that airway reflexes have similar resuscitation potential as gasping respiration. Nasopharyngeal stimulation in cats and most mammals evokes the aspiration reflex, characterized by spasmodic inspiration followed by passive expiration. On the contrary, expiration reflex from the larynx, or cough reflex from the pharynx and lower airways manifest by a forced expiration, which in cough is preceded by deep inspiration. These reflexes of distinct character activate the brainstem rhythm generators for inspiration and expiration strongly, but differently. They secondarily modulate the control mechanisms of various vital functions of the organism. During severe asphyxia the progressive respiratory insufficiency may induce a life-threatening cardio-respiratory failure. The sniff- and gasp-like aspiration reflex and similar spasmodic inspirations, accompanied by strong sympatho-adrenergic activation, can interrupt a severe asphyxia and reverse the developing dangerous cardiovascular and vasomotor dysfunctions, threatening with imminent loss of consciousness and death. During progressive asphyxia the reversal of gradually developing bradycardia and excessive hypotension by airway reflexes starts with reflex tachycardia and vasoconstriction, resulting in prompt hypertensive reaction, followed by renewal of cortical activity and gradual normalization of breathing. A combination of the aspiration reflex supporting venous return and the expiration or cough reflex increasing the cerebral perfusion by strong expirations, provides a powerful resuscitation and

  1. Resuscitation and auto resuscitation by airway reflexes in animals

    PubMed Central

    2013-01-01

    Various diseases often result in decompensation requiring resuscitation. In infants moderate hypoxia evokes a compensatory augmented breath – sigh and more severe hypoxia results in a solitary gasp. Progressive asphyxia provokes gasping respiration saving the healthy infant – autoresuscitation by gasping. A neonate with sudden infant death syndrome, however, usually will not survive. Our systematic research in animals indicated that airway reflexes have similar resuscitation potential as gasping respiration. Nasopharyngeal stimulation in cats and most mammals evokes the aspiration reflex, characterized by spasmodic inspiration followed by passive expiration. On the contrary, expiration reflex from the larynx, or cough reflex from the pharynx and lower airways manifest by a forced expiration, which in cough is preceded by deep inspiration. These reflexes of distinct character activate the brainstem rhythm generators for inspiration and expiration strongly, but differently. They secondarily modulate the control mechanisms of various vital functions of the organism. During severe asphyxia the progressive respiratory insufficiency may induce a life-threatening cardio-respiratory failure. The sniff- and gasp-like aspiration reflex and similar spasmodic inspirations, accompanied by strong sympatho-adrenergic activation, can interrupt a severe asphyxia and reverse the developing dangerous cardiovascular and vasomotor dysfunctions, threatening with imminent loss of consciousness and death. During progressive asphyxia the reversal of gradually developing bradycardia and excessive hypotension by airway reflexes starts with reflex tachycardia and vasoconstriction, resulting in prompt hypertensive reaction, followed by renewal of cortical activity and gradual normalization of breathing. A combination of the aspiration reflex supporting venous return and the expiration or cough reflex increasing the cerebral perfusion by strong expirations, provides a powerful resuscitation

  2. Vibration paradox and H-reflex suppression: is H-reflex suppression results from distorting effect of vibration?

    PubMed

    Cakar, H I; Cidem, M; Kara, S; Karacan, I

    2014-09-01

    Vibration paradox is that an increase in muscles activity coexists with the inhibition of H-reflex during vibration. The H-reflex suppression may be due to the movement of stimulating electrode during vibration. The aim of this study was to test this hypothesis. Fifteen healthy young adult males participated in this study. The soleus myoelectrical activities were evaluated by surface electromyography (SEMG). The vibration was applied only to the left leg and the H-reflex of soleus muscle was measured in the right leg to prevent the probable measurement errors caused by the movement of stimulating electrode. The Hmax/Mmax ratio of the right soleus isolated from vibration effects significantly decreased during the left leg vibration. As a result, this study shows that the H-reflex is suppressed during the vibration and the movement of the stimulating electrode has no role on the suppression of H-reflex.

  3. The Chinchilla's vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Merwin, W. H., Jr.; Wall, Conrad, III; Tomko, D. L.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) was measured and characterized in seven adult chinchillas using 0.01 to 1.0 Hz angular velocity sinusoids. Gains were less than compensatory, and were variable from day to day, but phases were highly repeatable both within and between animals. The best fitting transfer function to the average data of all animals had a dominant time constant of 7.5 sec, and an adaptation operator with a time constant of 24.0 sec. There were certain nonlinearities in the horizontal VOR of this animal, and it was difficult to elicit a robust optokinetic response. Results are discussed in relation to similar measurements in other species.

  4. Vestibular-ocular accommodation reflex in man

    NASA Technical Reports Server (NTRS)

    Clark, B.; Randle, R. J.; Stewart, J. D.

    1975-01-01

    Stimulation of the vestibular system by angular acceleration produces widespread sensory and motor effects. The present paper studies a motor effect which has not been reported in the literature, i.e., the influence of rotary acceleration of the body on ocular accommodation. The accommodation of 10 young men was recorded before and after a high-level deceleration to zero velocity following 30 sec of rotating. Accommodation was recorded continuously on an infrared optometer for 110 sec under two conditions: while the subjects observed a target set at the far point, and while they viewed the same target through a 0.3-mm pinhole. Stimulation by high-level rotary deceleration produced positive accommodation or a pseudomyopia under both conditions, but the positive accommodation was substantially greater and lasted much longer during fixation through the pinhole. It is hypothesized that this increase in accommodation is a result of a vestibular-ocular accommodation reflex.

  5. Cultural Reflexivity in Health Research and Practice

    PubMed Central

    Aronowitz, Robert; Deener, Andrew; Keene, Danya; Schnittker, Jason

    2015-01-01

    Recent public health movements have invoked cultural change to improve health and reduce health disparities. We argue that these cultural discourses have sometimes justified and maintained health inequalities when those with power and authority designated their own social practices as legitimate and healthy while labeling the practices of marginalized groups as illegitimate or unhealthy. This “misrecognition,” which creates seemingly objective knowledge without understanding historical and social conditions, sustains unequal power dynamics and obscures the fact that what is deemed legitimate and healthy can be temporally, geographically, and socially relative. We use examples from research across multiple disciplines to illustrate the potential consequences of cultural misrecognition, highlight instances in which culture was invoked in ways that overcame misrecognition, and discuss how cultural reflexivity can be used to improve health research and practice. PMID:25905833

  6. Vestibulospinal reflexes as a function of microgravity

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.; Homick, J. L.; Anderson, D. J.

    1984-01-01

    Data from previous manned space flights suggest that an exposure to microgravity produces significant alterations in vestibular, neuromuscular, and related sensory system functions. It is possible that the observed changes are a function of adaptation induced by altered otolith input. An experiment in Spacelab 1 was conducted with the aim to study this adaptation as it occurred in flight and after flight, and to relate the observed changes to mechanisms underlying space motion sickness. The concept was explored by making use of the anatomic pathway which links the otolith organs and spinal motoneurons. The overall sensitivity of the spinal motoneurons was tested by two related methods. One method involves the electrical excitation of neural tissue and the recording of vestibulospinal reflexes in conjunction with a brief linear acceleration. The second method is concerned with measurements of dynamic postural ataxia. Results suggest that more than a single time constant may be involved in man's ability to return to baseline values.

  7. Bremsstrahlung target optimization for reflex triodes

    SciTech Connect

    Swanekamp, S. B.; Weber, B. V.; Stephanakis, S. J.; Mosher, D.; Commisso, R. J.

    2008-08-15

    The anode (tantalum) foil thickness in a reflex triode was varied from 2.5 to 250 {mu}m to maximize the dose from bremsstrahlung produced by a 1 MV, 1 MA, 100 ns electron beam. Experiments and computer simulations show that the dose is maximized for a foil thickness of about 25 {mu}m, 1/18th of the electron range computed from the continuous slowing down approximation. For foils thicker than optimum, self-absorption in the foil attenuates 10-100 keV photons, reducing the dose. For foils thinner than optimum, the dose decreases as a result of electron migration to large radius. A simple formula that predicts the optimum thickness as a function of the beam current and voltage is derived that should be applicable to a large range of experimental parameters.

  8. Cultural reflexivity in health research and practice.

    PubMed

    Aronowitz, Robert; Deener, Andrew; Keene, Danya; Schnittker, Jason; Tach, Laura

    2015-07-01

    Recent public health movements have invoked cultural change to improve health and reduce health disparities. We argue that these cultural discourses have sometimes justified and maintained health inequalities when those with power and authority designated their own social practices as legitimate and healthy while labeling the practices of marginalized groups as illegitimate or unhealthy. This "misrecognition," which creates seemingly objective knowledge without understanding historical and social conditions, sustains unequal power dynamics and obscures the fact that what is deemed legitimate and healthy can be temporally, geographically, and socially relative. We use examples from research across multiple disciplines to illustrate the potential consequences of cultural misrecognition, highlight instances in which culture was invoked in ways that overcame misrecognition, and discuss how cultural reflexivity can be used to improve health research and practice.

  9. In vitro receptivity of carbonate rocks to endolithic lichen-forming aposymbionts.

    PubMed

    Favero-Longo, Sergio E; Borghi, Alessandro; Tretiach, Mauro; Piervittori, Rosanna

    2009-10-01

    Sterile cultured isolates of lichen-forming aposymbionts have not yet been used to investigate lichen-rock interactions under controlled conditions. In this study mycobionts and photobiont of the endolithic lichens Bagliettoa baldensis and Bagliettoa marmorea were isolated and inoculated with coupons of one limestone and four marbles commonly employed in the Cultural Heritage framework. After one year of incubation, microscopic observations of polished cross-sections were performed to verify if the typical colonization patterns observed in the field may be reproduced in vitro and to evaluate the receptivity of the five lithotypes to endolithic lichens. The mycobionts of the two species developed both on the surface of and within all the lithotypes, showing different penetration pathways which depend on mineralogical and structural features and highlight different receptivity. By contrast, algae inoculated with the coupons did not penetrate them. Observations suggest that the hyphal penetration along intrinsic discontinuities of rocks is a relatively fast phenomenon when these organisms are generally considered as slow-growing. Samples from limestone outcrops and abandoned marble quarries, colonized by the same species or other representatives of Verrucariaceae, showed penetration pathways intriguingly similar to those reproduced in vitro and highlighted that lichen-driven erosion processes only increase the availability of hyphal passageways after a long-term colonization. These results show that in vitro incubation of sterile cultured lichen-forming ascomycetes with rock coupons is a practicable experimental system to investigate the lichen-rock interactions under controlled conditions and, together with analysis in situ, may support decisions on conservative treatments of historical and cultural significant stone substrata. PMID:19683572

  10. On the receptivity problem for Goertler vortices: Vortex motions induced by wall roughness

    NASA Technical Reports Server (NTRS)

    Denier, James P.; Hall, Philip; Seddougui, Sharon

    1990-01-01

    The receptivity problem for Goertler vortices induced by wall roughness is investigated. The roughness is modelled by small amplitude perturbations to the curved wall over which the flow takes place. The amplitude of these perturbations is taken to be sufficiently small for the induced Goertler vortices to be described by linear theory. The roughness is assumed to vary in the spanwise direction on the boundary layer lengthscale, while in the flow direction the corresponding variation is on the lengthscale over which the wall curvature varies. In fact the latter condition can be relaxed to allow for a faster streamwise roughness variation so long as the variation does not become as fast as that in the spanwise direction. The function which describes the roughness is assumed to be such that its spanwise and streamwise dependences can be separated; this enables progress by taking Fourier or Laplace transforms where appropriate. The cases of isolated and distributed roughness elements are investigated and the coupling coefficient which relates the amplitude of the forcing and the induced vortex amplitude is found asymptotically in the small wavelength limit. It is shown that this coefficient is exponentially small in the latter limit so that it is unlikely that this mode can be stimulated directly by wall roughness. The situation at 0(1) wavelengths is quite different and this is investigated numerically for different forcing functions. It is found that an isolated roughness element induces a vortex field which grows within a wedge at a finite distance downstream of the element. However, immediately downstream of the obstacle the disturbed flow produced by the element decays in amplitude. The receptivity problem at larger Goertler numbers appropriate to relatively large wall curvature is discussed in detail.

  11. Conditioning the middle ear reflex at sensation levels below reflex threshold: air jet and electrical stimulation.

    PubMed

    McDaniel-Bacon, L; Fulton, R T; Laskowski, R P

    1980-01-01

    An ABAB functional analysis, conditioning and generalization, design was used in 3 experiments (2 were formal studies and 1 was empirical in nature) to investigate the conditionability of the middle ear reflex. The conditioned stimuli were subreflex threshold pure tones of various frequencies and intensities. The unconditioned stimulus (UCS) was an auricular air jet to the contralateral ear in the first experiment and cutaneous electrical stimulation to the ipsolateral, probe ear in the last 2 experiments. Reflexes were monitored by an otoadmittance meter, storage oscilloscope, and strip chart recorder. In the first experiment (air jet UCS), no subjects met the conditioning criterion within the maximum presentation of 400 paired trials, despite pilot evidence which indicated conditioning was feasible. In the second experiment (electrical stimulation UCS), 2 subjects met conditioning criterion; however, only one subject reconditioned and demonstrated partial generalization to other conditioned stimuli. In the third experiment (electrical stimulation UCS), one of 3 subjects who had previously been unconditionable with the air jet UCS met conditioning and reconditioning criterion and demonstrated partial generalization. Results indicate that the middle ear reflex can be conditioned to be elicited by subreflex threshold pure tones, however, results are limited.

  12. Receptivity of a TVD Scheme in Incompressible Flow Analysis

    NASA Astrophysics Data System (ADS)

    Shin, Byeong Rog

    A TVD upwind scheme originally designed for compressible flow is applied to the SMAC finite-difference method for incompressible flow analysis. The receptivity and validity of this application are investigated by an evaluation of the accuracy, stability and convergence rate for the SMAC method combined with the TVD scheme. Using this method, three-dimensional developing entry flows through a square-curved duct are calculated and compared with available experimental data as well as some computational results obtained by QUICKs and third-order upwind schemes. Such comparisons show that the numerical method applying the TVD scheme has the highest computational efficiency without a sharp loss of accuracy, resulting in confidence in the application this scheme to incompressible flow computations.

  13. The Origin and Earliest Reception of Big-Bang Cosmology

    NASA Astrophysics Data System (ADS)

    Kragh, H.

    2008-10-01

    The basic idea of big-bang cosmology is that the universe came into being a finite time ago and since then developed into its present state. More or less scientifically based versions of this idea can be found in the nineteenth century, but it was only after Einstein's general theory of relativity that it became possible to speak of a dynamical universe in a full sense. Although mathematical models of a big-bang universe were included in Friedmann's theory of 1922, the true beginning of (physical) big-bang cosmology should be dated to 1931, when Lemaître suggested his picture of the primordial state of the universe as a giant atomic nucleus. This paper outlines the origin of the big-bang hypothesis and pays particular attention to the works of Lemaître. It also deals with the earliest reception of the hypothesis, but only up to the mid-1930s.

  14. Vertical array receptions of the Heard Island transmissions

    SciTech Connect

    Baggeroer, A.B. ); Lashkari, K. ); Chiu, Ching-sang; Miller, J.H. ); Mikhalevsky, P. ); von der Heydt, K. (Woods Hole Oceanographic Institution

    1993-03-23

    The Heard Island Feasibility Test (HIFT) demonstrated that coded acoustic signals could be detected at ranges up to 18,000 km with currently available source technology. This paper describes one component of the HIFT where a large aperture vertical line array was deployed to record the signals transmitted from Heard Island. We have performed four analysis Of the VLA receptions, of the Heard Island signals. All four suggest the presence of higher order modes. The frequency- vertical wavenumber analysis and the modal beamforming indicate that mode 3 has the highest amplitude while the modal fitting suggests that made 5--6 are largest. It is difficult to resolve the differences since the SNR at the VLA, nearly 18,000 km with a transmission loss of around 145 dB, is quite low. Individual arrivals could not be distinguished because of the long integration time necessitated by the low SNR.

  15. Concept for low-cost chaos radar using coherent reception

    NASA Astrophysics Data System (ADS)

    Blakely, Jonathan N.; Corron, Ned J.

    2011-06-01

    We describe a new approach to random-signal radar based on the recent discovery of analytically solvable chaotic oscillators. These surprising nonlinear systems generate random, aperiodic waveforms that offer an exact analytic representation, allowing the implementation of simple matched filters and coherent reception. Notably, this approach enables nearly optimal detection of noise-like waveforms without need for expensive variable delay lines to store wideband waveforms for correlation. Mathematically, the waveform is expressed as a linear convolution of a bit sequence with a fixed basis function. We realize a simple matched filter for the waveform using a linear filter whose impulse response function is the time reverse of the basis function. Importantly, linear filters matched to finite bit sequences can be defined, enabling pulse compression and spread spectrum radar. We present an example oscillator, its matched filter, and simulation results demonstrating the pulse compression radar concept.

  16. Sudomotor function in sympathetic reflex dystrophy.

    PubMed

    Birklein, F; Sittl, R; Spitzer, A; Claus, D; Neundörfer, B; Handwerker, H O

    1997-01-01

    Sudomotor functions were studied in 27 patients suffering from reflex sympathetic dystrophy (RSD) according to the criteria established by Bonica (18 women, 9 men; mean age 50 +/- 12.3 years; median duration of disease 8 weeks, range 2-468 weeks). To measure local sweating rates, two small chambers (5 cm2) were affixed to corresponding areas of hairy skin on the affected and unaffected limbs. Dry nitrogen gas was passed through the chambers (270 ml/min) and evaporation was recorded at both devices with hygrometers. Thermoregulatory sweating (TST) was induced by raising body temperature (intake of 0.5 1 hot tea and infra-red irradiation). Local sweating was also induced through an axon reflex (QSART) by transcutaneous iontophoretic application of carbachol (5 min, 1 mA). In addition, skin temperature was measured on the affected and unaffected side by infra-red thermography. Mean skin temperature was significantly higher on the affected side (P < 0.003). In spite of the temperature differences, there was no difference in basal sweating on the affected and unaffected side. However, both methods of sudomotor stimulation lead to significantly greater sweating responses on the affected compared to the unaffected side (TST: P < 0.05, QSART: P < 0.004). Latency to onset of sweating was significantly shorter on the affected side under both test conditions (P < 0.04 and P < 0.003, respectively). Sweat responses were not correlated to absolute skin temperature but were probably related to the increased blood flow on the affected side. Our findings imply a differential disturbance of vasomotor and sudomotor mechanisms in affected skin. Whereas vasoconstrictor activity is apparently lowered, sudomotor output is either unaltered or may even be enhanced.

  17. Static ocular counterroll reflex in skew deviation

    PubMed Central

    Chandrakumar, M.; Blakeman, A.; Goltz, H.C.; Sharpe, J.A.

    2011-01-01

    Objective: The static ocular counterroll (OCR) reflex generates partially compensatory torsional eye movements during head roll. It is mediated by the utricle in the inner ear. Skew deviation is a vertical strabismus thought to be caused by imbalance in the utriculo-ocular pathway. We hypothesized that if skew deviation is indeed caused by damage to this reflex pathway, patients with skew deviation would show abnormal OCR. Methods: Eighteen patients with skew deviation caused by brainstem or cerebellar lesions and 18 normal participants viewed a target at 1 m. Ocular responses to static passive head roll-tilts of approximately 20° were recorded using search coils. Static OCR gain was calculated as the change in torsional eye position divided by the change in head position during sustained head roll. Perception of the subjective visual vertical (SVV) was also measured. Results: Group mean OCR gain was reduced by 45% in patients. At an individual level, OCR gains were asymmetric between eyes and between torsional directions in 90% of patients. In addition, the hypotropic eye incyclotorting gain was lower than the hypertropic eye excyclotorting gain during head roll toward the hypotropic eye in 94% of patients. No consistent pattern of gain asymmetry was found during head roll toward the hypertropic eye. The SVV was tilted toward the hypotropic eye. Conclusion: Static OCR gain is significantly reduced in skew deviation. Interocular and directional gain asymmetries are also prevalent. The asymmetries provide further evidence that disruption of the utriculo-ocular pathway is a mechanism for skew deviation. PMID:21813791

  18. Sudomotor function in sympathetic reflex dystrophy.

    PubMed

    Birklein, F; Sittl, R; Spitzer, A; Claus, D; Neundörfer, B; Handwerker, H O

    1997-01-01

    Sudomotor functions were studied in 27 patients suffering from reflex sympathetic dystrophy (RSD) according to the criteria established by Bonica (18 women, 9 men; mean age 50 +/- 12.3 years; median duration of disease 8 weeks, range 2-468 weeks). To measure local sweating rates, two small chambers (5 cm2) were affixed to corresponding areas of hairy skin on the affected and unaffected limbs. Dry nitrogen gas was passed through the chambers (270 ml/min) and evaporation was recorded at both devices with hygrometers. Thermoregulatory sweating (TST) was induced by raising body temperature (intake of 0.5 1 hot tea and infra-red irradiation). Local sweating was also induced through an axon reflex (QSART) by transcutaneous iontophoretic application of carbachol (5 min, 1 mA). In addition, skin temperature was measured on the affected and unaffected side by infra-red thermography. Mean skin temperature was significantly higher on the affected side (P < 0.003). In spite of the temperature differences, there was no difference in basal sweating on the affected and unaffected side. However, both methods of sudomotor stimulation lead to significantly greater sweating responses on the affected compared to the unaffected side (TST: P < 0.05, QSART: P < 0.004). Latency to onset of sweating was significantly shorter on the affected side under both test conditions (P < 0.04 and P < 0.003, respectively). Sweat responses were not correlated to absolute skin temperature but were probably related to the increased blood flow on the affected side. Our findings imply a differential disturbance of vasomotor and sudomotor mechanisms in affected skin. Whereas vasoconstrictor activity is apparently lowered, sudomotor output is either unaltered or may even be enhanced. PMID:9060012

  19. Perceptual rivalry: reflexes reveal the gradual nature of visual awareness.

    PubMed

    Naber, Marnix; Frässle, Stefan; Einhäuser, Wolfgang

    2011-01-01

    Rivalry is a common tool to probe visual awareness: a constant physical stimulus evokes multiple, distinct perceptual interpretations ("percepts") that alternate over time. Percepts are typically described as mutually exclusive, suggesting that a discrete (all-or-none) process underlies changes in visual awareness. Here we follow two strategies to address whether rivalry is an all-or-none process: first, we introduce two reflexes as objective measures of rivalry, pupil dilation and optokinetic nystagmus (OKN); second, we use a continuous input device (analog joystick) to allow observers a gradual subjective report. We find that the "reflexes" reflect the percept rather than the physical stimulus. Both reflexes show a gradual dependence on the time relative to perceptual transitions. Similarly, observers' joystick deflections, which are highly correlated with the reflex measures, indicate gradual transitions. Physically simulating wave-like transitions between percepts suggest piece-meal rivalry (i.e., different regions of space belonging to distinct percepts) as one possible explanation for the gradual transitions. Furthermore, the reflexes show that dominance durations depend on whether or not the percept is actively reported. In addition, reflexes respond to transitions with shorter latencies than the subjective report and show an abundance of short dominance durations. This failure to report fast changes in dominance may result from limited access of introspection to rivalry dynamics. In sum, reflexes reveal that rivalry is a gradual process, rivalry's dynamics is modulated by the required action (response mode), and that rapid transitions in perceptual dominance can slip away from awareness. PMID:21677786

  20. Cardiorespiratory parameters and respiratory reflexes in rabbits during hyperthermia.

    PubMed

    Javorka, K; Calkovská, A; Petrásková, M; Gecelovská, V

    1996-01-01

    The effects of different body temperature (BT) on the respiratory and cardiovascular parameters and respiratory reflexes were studied in 33 anaesthetized adult rabbits. Hyperthermia elicited panting with mean panting respiratory rate 199 +/- 14 x min-1 in all anaesthetized rabbits. Significant correlations between BT and frequency of breathing (positive), heart rate (positive) or tidal volume (negative) were found. Cooling was accompanied by considerable arterial hypotension. Duration of the Hering-Breuer reflex (HB) was reduced by the rise of BT. Intensity of the reflex (assessed as the ratio of the apnoeic pause to the mean duration of the previous 5 breaths) was unchanged up to the body temperature eliciting panting (41.15 +/- 0.08 degrees C) when it was greatly diminished. Defensive airway reflexes were also changed in hyperthermia. The duration as well as the intensity of nasal apnoea (Kratschmer's reflex) and laryngeal chemoreflex apnoea were decreased. The intensities of respiratory efforts in sneezing and laryngeal coughing were reduced. The expulsive reactions evoked by mechanical stimulation of the larynx were replaced by very shortlasting inhibition of breathing during panting. The results indicate that reflex control of breathing via the Hering-Breuer reflex and the ability to eliminate irritants from the airways are diminished during hyperthermia and panting in anaesthetized rabbits. PMID:9085374

  1. Perceived context of reception among recent Hispanic immigrants: conceptualization, instrument development, and preliminary validation.

    PubMed

    Schwartz, Seth J; Unger, Jennifer B; Lorenzo-Blanco, Elma I; Des Rosiers, Sabrina E; Villamar, Juan A; Soto, Daniel W; Pattarroyo, Monica; Baezconde-Garbanati, Lourdes; Szapocznik, José

    2014-01-01

    Context of reception has been discussed widely in the sociological and anthropological literature, but no measures of this construct exist. We designed a measure of perceived context of reception and provide initial support for the factorial validity, internal consistency reliability, and incremental and discriminant validity of scores generated by this measure. A sample of 302 recent-immigrant Hispanic parent-adolescent dyads from Miami and Los Angeles completed the new perceived context of reception measure, as well as measures of perceived discrimination; Hispanic/American cultural practices, values, and identifications; and depressive symptoms. In Phase 1, exploratory and confirmatory factor analyses extracted a factor for negative perceived context of reception. A subscale corresponding to this factor was used in Phase 2; for parents and adolescents, negative perceived context of reception and perceived discrimination were differentially associated with acculturation-related variables-suggesting discriminant validity between perceived discrimination and negative perceived context of reception. For adolescents at both sites and for parents in Los Angeles only, the negative perceived context of reception dimensions were significantly associated with depressive symptoms 6 months later, over and above the contribution made by perceived discrimination--suggesting incremental validity. Results are discussed in terms of perceived context of reception as a new and emerging construct. PMID:24099485

  2. Perceived Context of Reception among Recent Hispanic Immigrants: Conceptualization, Instrument Development, and Preliminary Validation

    PubMed Central

    Schwartz, Seth J.; Unger, Jennifer B.; Lorenzo-Blanco, Elma I.; Des Rosiers, Sabrina E.; Villamar, Juan A.; Soto, Daniel W.; Pattarroyo, Monica; Baezconde-Garbanati, Lourdes; Szapocznik, José

    2013-01-01

    Context of reception has been discussed widely in the sociological and anthropological literature, but no measures of this construct exist. We designed a measure of perceived context of reception and provide initial support for the factorial validity, internal consistency reliability, and incremental and discriminant validity of scores generated by this measure. A sample of 302 recent-immigrant Hispanic parent-adolescent dyads from Miami and Los Angeles completed the new perceived context of reception measure, as well as measures of perceived discrimination; Hispanic/American cultural practices, values, and identifications; and depressive symptoms. In Phase 1, exploratory and confirmatory factor analyses extracted a factor for negative perceived context of reception. A subscale corresponding to this factor was used in Phase 2; for parents and adolescents, negative perceived context of reception and perceived discrimination were differentially associated with acculturation-related variables – suggesting discriminant validity between perceived discrimination and negative perceived context of reception. For adolescents at both sites and for parents in Los Angeles only, the negative perceived context of reception dimensions were significantly associated with depressive symptoms six months later, over and above the contribution made by perceived discrimination – suggesting incremental validity. Results are discussed in terms of perceived context of reception as a new and emerging construct. PMID:24099485

  3. Perceived context of reception among recent Hispanic immigrants: conceptualization, instrument development, and preliminary validation.

    PubMed

    Schwartz, Seth J; Unger, Jennifer B; Lorenzo-Blanco, Elma I; Des Rosiers, Sabrina E; Villamar, Juan A; Soto, Daniel W; Pattarroyo, Monica; Baezconde-Garbanati, Lourdes; Szapocznik, José

    2014-01-01

    Context of reception has been discussed widely in the sociological and anthropological literature, but no measures of this construct exist. We designed a measure of perceived context of reception and provide initial support for the factorial validity, internal consistency reliability, and incremental and discriminant validity of scores generated by this measure. A sample of 302 recent-immigrant Hispanic parent-adolescent dyads from Miami and Los Angeles completed the new perceived context of reception measure, as well as measures of perceived discrimination; Hispanic/American cultural practices, values, and identifications; and depressive symptoms. In Phase 1, exploratory and confirmatory factor analyses extracted a factor for negative perceived context of reception. A subscale corresponding to this factor was used in Phase 2; for parents and adolescents, negative perceived context of reception and perceived discrimination were differentially associated with acculturation-related variables-suggesting discriminant validity between perceived discrimination and negative perceived context of reception. For adolescents at both sites and for parents in Los Angeles only, the negative perceived context of reception dimensions were significantly associated with depressive symptoms 6 months later, over and above the contribution made by perceived discrimination--suggesting incremental validity. Results are discussed in terms of perceived context of reception as a new and emerging construct.

  4. Receptive Vocabulary in Boys with Autism Spectrum Disorder: Cross-Sectional Developmental Trajectories

    ERIC Educational Resources Information Center

    Kover, Sara T.; McDuffie, Andrea S.; Hagerman, Randi J.; Abbeduto, Leonard

    2013-01-01

    In light of evidence that receptive language may be a relative weakness for individuals with autism spectrum disorder (ASD), this study characterized receptive vocabulary profiles in boys with ASD using cross-sectional developmental trajectories relative to age, nonverbal cognition, and expressive vocabulary. Participants were 49 boys with ASD…

  5. Genome-Wide Association Study of Receptive Language Ability of 12-Year-Olds

    ERIC Educational Resources Information Center

    Harlaar, Nicole; Meaburn, Emma L.; Hayiou-Thomas, Marianna E.; Davis, Oliver S. P.; Docherty, Sophia; Hanscombe, Ken B.; Haworth, Claire M. A.; Price, Thomas S.; Trzaskowski, Maciej; Dale, Philip S.; Plomin, Robert

    2014-01-01

    Purpose: Researchers have previously shown that individual differences in measures of receptive language ability at age 12 are highly heritable. In the current study, the authors attempted to identify some of the genes responsible for the heritability of receptive language ability using a "genome-wide association" approach. Method: The…

  6. The Reception of German Progressive Education in Russia: On Regularities of International Educational Transfer

    ERIC Educational Resources Information Center

    Mchitarjan, Irina

    2015-01-01

    This article reports a historical case study of extensive educational transfer: the reception, adaptation, and use of German progressive education and German school reform ideas and practices in Russia at the beginning of the twentieth century. The reception of German educational ideas greatly enriched the theory and practice of the Russian school…

  7. Building a Transfer-Receptive Culture at Four-Year Institutions

    ERIC Educational Resources Information Center

    Herrera, Alfred; Jain, Dimpal

    2013-01-01

    This chapter reviews a four-year university's role in developing and implementing a transfer-receptive culture. In particular, it focuses on the first element of a transfer-receptive culture by highlighting a series of visits by the chancellor of the University of California, Los Angeles, to community colleges within California. Strengthening…

  8. Principal Change Facilitator Style, Bureaucratic and Professional Orientations, and Teacher Receptivity to Change.

    ERIC Educational Resources Information Center

    Chauvin, Sheila W.; Ellett, Chad D.

    Conceptions of principal change facilitator style (PCFS) and bureaucratic and professional role orientations (BPROs) are used to explore the construct of teacher receptivity to change (TRC) and the relationships among teacher perceptions of PCFS and their perceptions of receptivity to change. Part I of the study analyzed and refined the…

  9. Effective Strategies for Turning Receptive Vocabulary into Productive Vocabulary in EFL Context

    ERIC Educational Resources Information Center

    Faraj, Avan Kamal Aziz

    2015-01-01

    Vocabulary acquisition has been a main concern of EFL English teachers and learners. There have been tons of research to examine the student's level of receptive vocabulary and productive vocabulary, but no research has conducted on how turning receptive vocabulary into productive vocabulary. This study has reported the impact of the teaching…

  10. An Examination of College Students' Receptiveness to Alcohol-Related Information and Advice

    ERIC Educational Resources Information Center

    Leahy, Matthew M.; Jouriles, Ernest N.; Walters, Scott T.

    2013-01-01

    This project examined the reliability and validity of a newly developed measure of college students' receptiveness to alcohol related information and advice. Participants were 116 college students who reported having consumed alcohol at some point in their lifetime. Participants completed a measure of receptiveness to alcohol-related…

  11. Asynchronous development of stigmatic receptivity in the pear (Pyrus communis; Rosaceae) flower.

    PubMed

    Sanzol, Javier; Rallo, Pilar; Herrero, María

    2003-01-01

    While stigma anatomy is well documented for a good number of species, little information is available on the acquisition and cessation of stigmatic receptivity. The aim of this work is to characterize the development of stigma receptivity, from anthesis to stigma degeneration, in the pentacarpellar pear (Pyrus communis) flower. Stigma development and stigmatic receptivity were monitored over two consecutive years, as the capacity of the stigmas to offer support for pollen germination and pollen tube growth. In an experiment where hand pollinations were delayed for specified times after anthesis, three different stigmatic developmental stages could be observed: (1) immature stigmas, which allow pollen adhesion but not hydration; (2) receptive stigmas, which allow proper pollen hydration and germination; and (3) degenerated stigmas, in which pollen hydrates and germinates properly, but pollen tube growth is impaired soon after germination. This developmental characterization showed that stigmas in different developmental stages coexist within a flower and that the acquisition and cessation of stigmatic receptivity by each carpel occur in a sequential manner. In this way, while the duration of stigmatic receptivity for each carpel is rather short, the flower has an expanded receptive period. This asynchronous period of receptivity for the different stigmas of a single flower is discussed as a strategy that could serve to maximize pollination resources under unreliable pollination conditions.

  12. The Effects of Receptive and Productive Learning of Word Pairs on Vocabulary Knowledge

    ERIC Educational Resources Information Center

    Webb, Stuart

    2009-01-01

    English as a foreign language students in Japan learned target words in word pairs receptively and productively. Five aspects of vocabulary knowledge--orthography, association, syntax, grammatical functions, and meaning and form--were each measured by receptive and productive tests. The study uses an innovative methodology in that each target word…

  13. Receptivity toward Immigrants in Rural Pennsylvania: Perceptions of Adult English as Second Language Providers

    ERIC Educational Resources Information Center

    Prins, Esther; Toso, Blaire Willson

    2012-01-01

    This article uses interview and questionnaire data to examine how adult English as a second language (ESL) providers in rural Pennsylvania perceive community receptivity toward immigrants and the factors they believe foster or hinder receptivity and immigrants' integration. ESL providers' depictions of local responses to immigrants ranged from…

  14. Childhood Memories and Receptivity to Corrective Feedback in Group Supervision: Implications for Group Work

    ERIC Educational Resources Information Center

    Alexander, Angela; Hulse-Killacky, Diana

    2005-01-01

    This article presents findings from an exploration into supervisees' perspectives on childhood memories and receptivity to corrective feedback in group supervision. Historically, students' receptivity to corrective feedback has not been explored relative to their childhood memories. Ten graduate students from four practicum groups participated in…

  15. Reflex anuria: an old concept with new evidence.

    PubMed

    Hou, Weibin; Wen, Jin; Ji, Zhigang; Chen, Jian; Li, Hanzhong

    2014-02-01

    Reflex anuria (RA) was defined by Hull as cessation of urine output from both kidneys due to irritation or trauma to one kidney or its ureter, or severely painful stimuli to other organs. This is not a common concept among urologists or nephrologists even though it has been proposed for more than half a century. The phenomenon has not been thoroughly understood. But intrarenal arteriolar spasm and ureteral spasm have gained wide acceptance as the mechanisms of RA. The present review summarized papers published up to now on RA, in order to depict the general profile of the disease and to further elucidate the pathogenesis of RA. A classification system of RA was proposed as neurovascular reflex, ureterorenal reflex, radiated renovascular reflex, renoureteral reflex, ureteroureteral reflex and radiated ureteral reflex, based on the two assumed mechanisms and the stimulus' origins. All these types except renoureteral reflex had gained supporting evidence from animal experiments and/or clinical case reports. RA is a diagnosis of exclusion, only being considered after ruling out common and tangible etiologies such as ureteral calculi, acute tubular necrosis, renal vascular occlusion, hypovolemia, infection, etc. If the diagnosis has been established, treatment plan should be directed toward the mechanisms more than the causative factors. Abnormalities of the autonomic nerve system and congenital urogenital malformations incline people to RA. In summary, RA is a cessation of urine production caused by stimuli on kidney, ureter or other organs, through a mechanism of reflex spasm of intrarenal arterioles or ureters, leading to acute renal failure. It is a functional rather than parenchymal disease.

  16. Numerical Study of Hypersonic Boundary-Layer Receptivity and Stability with Freestream Hotspot Perturbations

    NASA Astrophysics Data System (ADS)

    Huang, Yuet

    This dissertation presents a numerical simulation study of linear hypersonic boundary-layer receptivity and stability over blunt compression cones with freestream hotspot perturbations. This study is conducted for freestream disturbances with broad, continuous frequency spectra over cones that have nose radii of 1, 0.5 and 0.1 mm under freestream conditions of Mach 6, 10 and 15. The simulations are carried out using the high-order shock-fitting finite-difference scheme developed by Zhong (1998), the results of which are shown to agree well with linear stability theory (LST) and experiments. The general receptivity mechanism is then studied by the simulation-LST comparisons under two parametric effects: nose bluntness and freestream Mach number. Among the new findings of the current study, the mechanisms of the receptivity process are found to be mainly caused by the fast acoustic waves that are generated behind the bow shock from the hotspot/shock interaction in the nose region. It is these fast acoustic waves that substantially enter the boundary layer and generate mode F through the synchronization of fast acoustic waves and mode F in the upstream part of the cone. Subsequently, the synchronization of modes F and S generates mode S, or the second mode, which eventually grows into a dominant level at the downstream part of the cone. Additionally, we have obtained the receptivity coefficients of mode S along the Branch-I neutral stability curve using a method that combines LST predicted N-factors and simulated disturbance amplitudes. These receptivity coefficients agree well with those obtained from the theoretical modal decomposition method. In addition to obtaining the general receptivity mechanism and receptivity coefficients, we have also studied the parametric effects of nose bluntness and freestream Mach number on boundary-layer receptivity and stability over cones. Specifically, our results have shown that nose bluntness reduces the boundary

  17. Reversible abnormalities of the Hering Breuer reflex in acrylamide neuropathy.

    PubMed Central

    Satchell, P

    1985-01-01

    The sensitivity of the Hering Breuer reflex was compared in anaesthetised rabbits before, during and after the induction of acrylamide neuropathy, and was measured as the tracheal pressure which produced 30 seconds of apnoea. After four weeks of acrylamide (400 mg/kg total dose) there was ataxia and the conduction velocity of hindlimb motor nerves was significantly reduced. At this time there was a marked and reproducible reduction in the sensitivity of the Hering Breuer reflex. The ataxia resolved within a month of stopping acrylamide administration. Three months after the cessation of acrylamide the sensitivity of the Hering Breuer reflex had increased significantly but had not returned to normal. PMID:2993526

  18. Primitive Reflexes and Attention-Deficit/Hyperactivity Disorder: Developmental Origins of Classroom Dysfunction

    ERIC Educational Resources Information Center

    Taylor, Myra; Houghton, Stephen; Chapman, Elaine

    2004-01-01

    The present research studied the symptomatologic overlap of AD/HD behaviours and retention of four primitive reflexes (Moro, Tonic Labyrinthine Reflex [TLR], Asymmetrical Tonic Neck Reflex [ATNR], Symmetrical Tonic Neck Reflex [STNR]) in 109 boys aged 7-10 years. Of these, 54 were diagnosed with AD/HD, 34 manifested sub-syndromal coordination,…

  19. Involvement of medial temporal structures in reflexive attentional shift by gaze

    PubMed Central

    Sato, Wataru; Kubota, Yasutaka; Usui, Keiko; Inoue, Yushi; Murai, Toshiya; Hayashi, Takuji; Toichi, Motomi

    2008-01-01

    Recent studies have revealed that eye gaze triggers reflexive shift of the observer's visuospatial attention to its direction even if it does not predict any events in the environment. To determine whether medial temporal structures are involved in this reflexive gaze processing, an experiment of the gaze-cuing paradigm was carried out in seven epileptic patients who had undergone unilateral temporal lobectomy and nine age- and IQ-matched epileptic controls who had not undergone any surgical treatments. Gaze cues were presented for 200 ms to the unilateral visual field, after which subjects were required to localize targets as quickly as possible. They were also instructed that gaze directions were not predictive of the location of the targets. When the gaze cues stimulated the intact hemisphere in lobectomized patients or either hemisphere in controls, reaction times for correct responses were significantly shorter when gaze directions were toward the targets than away from the targets. This cuing effect was not manifested following stimulation of the lesioned hemisphere in lobectomized patients. These findings suggest that the medial temporal structures, including the amygdala, play a crucial role in the reflexive shift of attention triggered by another person's gaze direction in humans. PMID:19015098

  20. Reflexive Research Ethics in Fetal Tissue Xenotransplantation Research

    PubMed Central

    Panikkar, Bindu; Smith, Natasha; Brown, Phil

    2013-01-01

    For biomedical research in which the only involvement of the human subject is the provision of tissue or organ samples, a blanket consent, i.e. consent to use the tissue for anything researchers wish to do, is considered by many to be adequate for legal and IRB requirements. Alternatively, a detailed informed consent provides patients or study participants with more thorough information about the research topic. We document here the beliefs and opinions of the research staff on informed consent and the discussion-based reflexive research ethics process that we employed in our fetal tissue xenotransplantion research on the impact of environmental exposures on fetal development. Reflexive research ethics entails the continued adjustment of research practice according to relational and reflexive understandings of what might be beneficent or harmful. Such reflexivity is not solely an individual endeavor, but rather a collective relationship between all actors in the research process. PMID:23074992

  1. Response characteristics of the human torsional vestibuloocular reflex

    NASA Technical Reports Server (NTRS)

    Peterka, Robert J.

    1992-01-01

    The characteristics of the response dynamics of the human torsional vestibuloocular reflex were studied during controlled rotations about an earth-horizontal axis. The results extended the frequency range to 2 Hz and identified the nonlinearity of the amplitude response.

  2. Speech Performance, Dysphagia and Oral Reflexes in Cerebral Palsy.

    ERIC Educational Resources Information Center

    Love, Russell J.; And Others

    1980-01-01

    The adequacy of biting, sucking, swallowing, and chewing as well as the presence or absence of nine infantile oral reflexes were assessed in 60 cerebral palsied individuals (ages 3 to 23). (Author/PHR)

  3. [Red reflex: prevention way to blindness in childhood].

    PubMed

    de Aguiar, Adriana Sousa Carvalho; Cardoso, Maria Vera Lúcia Moreira Leitão; Lúcio, Ingrid Martins Leite

    2007-01-01

    This study had as objective to investigate the result and the colour gradation of red reflex test in newborns (NB). It is a exploratory, quantitative study and the sample was 180 NB from maternity ward in Fortaleza-CE. From this, 156 showed result "no altered" and 24 "suspect". About the aspect of red reflex, 144 NB showed the same coloration in the two eyes, in 35 of this, the colour was red, in 33, orange reddish, in 46 orange colour, in 24 light yellow, in 6 yellow with whitish stains central. Of the suspect cases, the reflex was light yellow with whitish stains with lines. The nurse trained to accomplish the red reflex test can have important role at Neonatal Unit with actions about the prevention of ocular alterations in the childhood.

  4. Nasocardiac reflex during aspiration and injection through a nasogastric tube: An infrequent occurrence.

    PubMed

    Haldar, Rudrashish; Kaur, Jasleen; Bajwa, Sukhminder Jit Singh

    2015-04-01

    Nasocardiac reflex is a relatively less discussed variant of trigeminovagal reflex where the afferent arc of the reflex is represented by any of the branches of the trigeminal nerves, and the efferent arc is via the vagus nerve. Elicitation of this reflex is commonly seen during surgical manipulation and is manifested as bradycardia or even asystole. We report a case where nasocardiac reflex was unusually observed in a patient when aspiration and injection were done through a nasogastric tube.

  5. Mechanical Characteristics of Reflex Durign Upright Posture in Paralyzed Subjects

    NASA Astrophysics Data System (ADS)

    Kim, Yongchul; Youm, Youngil; Lee, Bumsuk; Kim, Youngho; Choi, Hyeonki

    The characteristics of flexor reflexes have been investigated in the previous studies with human subjects who were seated or supine position. However, researchers did not describe how the spinal circuits are used in different hip angles for paralyzed subjects, such as the standing position with walker or cane. In upright posture the compatibility between a flexor reflex of leg and body balance is a special problem for lower limb injured subjects. Therefore, the purpose of this study was to investigate the effects of hip angle change on the flexor reflex evoked in standing paralyzed subjects supported by walker. In this study, six spinal cord injured and four stroke subjects were recruited through the inpatient physical therapy clinics of Korea national rehabilitation hospital. A single axis electronic goniometer was mounted on the lateral side of the hip joint of the impaired limb to record movements in the sagittal plane at this joint. The electronic goniometer was connected to a data acquisition system, through amplifiers to a computer. Since subject' posture influenced characteristics of the flexion reflex response, the subjects were supported in an upright posture by the help of parallelogram walder. Two series of tests were performed on each leg. The first series of the tests investigated the influence of hip angle during stationary standing posture on flexion reflex response. The hip angle was adjusted by the foot plate. The second examined the effect of the voluntary action of subject on swing motion during the gait. The electrically induced flexion reflex simultaneously produced the flexion of the hip, knee and dorsiflexion of the ankle enabling the swing phase of walking. Form the experimental results we observed that the reflex response of hip joint was largerwith the hip in the extended position than in the flexed position during standing posture. Under voluntary movement on flexion reflex during gaint, the peak hip angle induced by stimulation was

  6. Cardiovascular Reflexes Activity and Their Interaction during Exercise

    PubMed Central

    Crisafulli, Antonio; Marongiu, Elisabetta; Ogoh, Shigehiko

    2015-01-01

    Cardiac output and arterial blood pressure increase during dynamic exercise notwithstanding the exercise-induced vasodilation due to functional sympatholysis. These cardiovascular adjustments are regulated in part by neural reflexes which operate to guarantee adequate oxygen supply and by-products washout of the exercising muscles. Moreover, they maintain adequate perfusion of the vital organs and prevent excessive increments in blood pressure. In this review, we briefly summarize neural reflexes operating during dynamic exercise with particular emphasis on their interaction. PMID:26557662

  7. An electronic device to record consensual reflex in human pupil.

    PubMed

    Pinheiro, H M; Costa, R M; Camilo, E N R; Gang, Hua

    2015-01-01

    Examination of the pupil offers an objective evaluation of visual function as well as the vegetative pathways to the eye. This work proposes the development of an effective method and a portable device to test the consensual pupillary reflex. The first results demonstrate the success of a new device construction and methodology to record the consensual reflex with different stimulus, in a situation of complete blockage of light.

  8. An experimental psychophysiological approach to human bradycardiac reflexes.

    PubMed

    Furedy, J J

    1985-01-01

    Bradycardic reflexes in man are both of scientific and clinical interest. Using the methods of experimental psychophysiology, control over relevant independent variables permits the study of fine-grained temporal physiologic response topographies, and of psychological factors that may modify the reflex. In addition, information can also be sought through interdisciplinary collaborations with experimental physiologists in order to shed light on the mechanism of the reflexes. These general features of the approach are illustrated by presenting data on two bradycardic reflex preparations: the laboratory dive analog, and the 90-degree negative tilt. The dive-analog studies have shown that a) the dive-reflex proper is a late-occurring bradycardia accompanied by a late-occurring vasoconstriction; and b) for the elicitation of this reflex, both breath-holding and face immersion are necessary. In addition, the physiologic manipulation of temperature affects the reflex in an inverse way over the range of 10 degrees to 40 degrees C, while the sense of control (a psychological variable) attenuates the reflex. The negative-tilt preparation produces a bradycardic response that is ideal as a Pavlovian unconditional response. Some Pavlovian conditioning arrangements, especially an "imaginational" form, do produce significant conditional bradycardic responding, and this has both potential clinical (e.g., biofeedback-related) and theoretical (e.g., S-R vs. S-S accounts of Pavlovian conditioning) applications. The paper ends with a comment on the cognitive paradigm shift in psychology. Although this shift is of importance, it is suggested that it is also important to "remember the response."

  9. Pupil Light Reflex Produced by Glare under Mesopic Adaptation

    NASA Astrophysics Data System (ADS)

    Colombo, Elisa; Comastri, Silvia Ana; Issolio, Luis; Echarri, Rodolfo

    The amount of light captured by the eye depends on pupil size. Moreover, one of the factors determining the steady-state pupil size is ambient illumination and sudden increments of light reaching the retina cause a brisk and transient pupil constriction described as the dynamic Pupil Light Reflex response. In experiments where a glare source acts as transient conditioning field, a methodology to measure pupil diameter is required. In the present paper pupil diameter, in steady (0.5 cd/m2) and dynamic adaptation conditions, is measured. The dynamic state is originated by a transient peripheral glare source with three different illuminance levels (15, 30 and 60 lx). Ten eyes of 5 subjects (19, 36, 50, 53 and 52 years old) are considered. The measurements are made by means of a video of the pupil captured with a CCD while the sight is fixated in a chart. In the steady condition, the average pupil diameter for each subject varies between 4.8 and 7.2 mm from one subject to another. In the dynamic condition, latency time results to be independent both of the subject and of the glare level, adding evidence to the robustness of this parameter when radiation is not incident centrally.

  10. Lipopolysaccharide does not affect acoustic startle reflex in mice.

    PubMed

    Juszczak, Grzegorz R; Blaszczyk, Janusz; Sadowski, Bogdan; Sliwa, Adam T; Wolak, Patrycja; Tymosiak-Zielinska, Agnieszka; Lisowski, Pawel; Swiergiel, Artur H

    2008-01-01

    Bacterial endotoxin (lipopolysaccharide; LPS) evokes in rodents an adaptive sickness behavior. It also produces changes in stress hormones secretion and activity of brain serotonergic and noradrenergic systems that have been implicated in stress responses, fear, and anxiety. Acoustic startle reflex (ASR) is regarded as a protective behavioral response that is enhanced in threatening situations or following an aversive event, and it can be modulated by physiological and emotional state of an animal. Effects of intraperitoneal injections of LPS on ASR, prepulse inhibition (PPI), locomotor activity in open field, and blood plasma corticosterone concentration were studied in lines of mice that display high (HA line) or low (LA line) swim stress-induced analgesia and also differ in emotional behaviors, including the magnitude of ASR. In both lines LPS produced robust sickness behavior, as evidenced by a decrease in locomotion and body weight, and an increase in corticosterone concentration. However, in neither line LPS injections affected responses to acoustic stimuli as assessed by the ASR and PPI magnitudes. The findings suggest that in sickness behavior induced by LPS the protective responses to salient environmental stimuli are not impaired. The significance of this finding for the concept of sickness behavior is discussed. PMID:17651939

  11. Modulation of trigeminal reflex excitability in migraine: effects of attention and habituation on the blink reflex.

    PubMed

    de Tommaso, Marina; Murasecco, Donatella; Libro, Giuseppe; Guido, Marco; Sciruicchio, Vittorio; Specchio, Luigi Maria; Gallai, Virgilio; Puca, Francomichele

    2002-06-01

    The modulation of trigeminal reflex excitability in migraine patients was evaluated during the asymptomatic phase by studying the effects of attention, habituation and preconditioning stimulus on the R2 and R3 components of the blink reflex (BR). Fifty patients suffering from migraine without aura, 20 affected by migraine with aura and 35 sex- and age-matched controls were selected. In subgroups of migraine with-aura and without-aura patients, and normal controls, the blink reflex was elicited during different cognitive situations: (a) spontaneous mental activity; (b) stimulus anticipation; (c) recognition of target numbers. In the remaining subjects, R2 and R3 habituation was evaluated by repetitive stimulation at 1, 5, 10, 15, 20, 25 and 30 s intervals. The R2 and R3 recovery curves were also computed. A reduced R3 threshold with a normal pain threshold was found in migraine with-aura and without-aura patients; the R3 component was not significantly correlated with the pain thresholds in patients and controls. The R2 and R3 components were less influenced by the warning of the stimulus in migraine without-aura and migraine with-aura patients, in comparison with the control group. A slight increase of both R2 and R3 recovery after preconditioning stimulus was also observed in migraine patients, probably caused by a phenomenon of trigeminal hyperexcitability persisting after the last attack. The abnormal BR modulation by alerting expresses in migraine a dysfunction of adaptation capacity to environmental conditions, probably predisposing to migraine. PMID:12031298

  12. Modulation of trigeminal reflex excitability in migraine: effects of attention and habituation on the blink reflex.

    PubMed

    de Tommaso, Marina; Murasecco, Donatella; Libro, Giuseppe; Guido, Marco; Sciruicchio, Vittorio; Specchio, Luigi Maria; Gallai, Virgilio; Puca, Francomichele

    2002-06-01

    The modulation of trigeminal reflex excitability in migraine patients was evaluated during the asymptomatic phase by studying the effects of attention, habituation and preconditioning stimulus on the R2 and R3 components of the blink reflex (BR). Fifty patients suffering from migraine without aura, 20 affected by migraine with aura and 35 sex- and age-matched controls were selected. In subgroups of migraine with-aura and without-aura patients, and normal controls, the blink reflex was elicited during different cognitive situations: (a) spontaneous mental activity; (b) stimulus anticipation; (c) recognition of target numbers. In the remaining subjects, R2 and R3 habituation was evaluated by repetitive stimulation at 1, 5, 10, 15, 20, 25 and 30 s intervals. The R2 and R3 recovery curves were also computed. A reduced R3 threshold with a normal pain threshold was found in migraine with-aura and without-aura patients; the R3 component was not significantly correlated with the pain thresholds in patients and controls. The R2 and R3 components were less influenced by the warning of the stimulus in migraine without-aura and migraine with-aura patients, in comparison with the control group. A slight increase of both R2 and R3 recovery after preconditioning stimulus was also observed in migraine patients, probably caused by a phenomenon of trigeminal hyperexcitability persisting after the last attack. The abnormal BR modulation by alerting expresses in migraine a dysfunction of adaptation capacity to environmental conditions, probably predisposing to migraine.

  13. Interaction of Baroreceptor and Chemoreceptor Reflexes MODULATION OF THE CHEMORECEPTOR REFLEX BY CHANGES IN BARORECEPTOR ACTIVITY

    PubMed Central

    Heistad, Donald D.; Abboud, Francois M.; Mark, Allyn L.; Schmid, Phillip G.

    1974-01-01

    The purpose of this study was to determine whether the level of arterial pressure and degree of baroreceptor activation affect responses to stimulation of chemoreceptors. Chemoreceptors were stimulated by injecting nicotine into the common carotid artery of anesthetized and paralyzed dogs. Responses were observed in the innervated gracilis muscle, perfused at constant flow while perfusion pressure was measured. Arterial pressure was lowered by bleeding the animals and raised by transient occlusion of the descending aorta. Vasoconstrictor responses to stimulation of chemoreceptors were enhanced by hypotension and inhibited by elevation of arterial pressure. Potentiation of the chemoreceptor reflex by hemorrhagic hypotension was not the result of altered vascular resistance in the gracilis muscle, sensitization of chemoreceptors by catecholamines or acidosis, or changes in cerebral perfusion pressure. Additional studies were done in which we excluded the possibility that the changes resulted from direct effects of changes in arterial pressure on chemoreceptors. Both carotid bifurcations were isolated and perfused. On one side, pressure was raised to stimulate the carotid sinus baroreceptors. On the other side, the carotid body chemoreceptors were stimulated by nicotine or by hypoxic and hypercapnic blood. Activation of baroreceptors on one side attenuated the vasoconstrictor response to chemoreceptor stimulation on the other side. This excludes a direct effect of changes in arterial pressure on the chemoreceptors and suggests a central interaction of these reflexes. We conclude that vasoconstrictor responses to stimulation of chemoreceptors are potentiated by hypotension and inhibited by transient hypertension. These effects appear to result at least in part from a central interaction of chemoreceptor and baroreceptor reflexes. PMID:4825222

  14. Auditory Brainstem Circuits That Mediate the Middle Ear Muscle Reflex

    PubMed Central

    Mukerji, Sudeep; Windsor, Alanna Marie; Lee, Daniel J.

    2010-01-01

    The middle ear muscle (MEM) reflex is one of two major descending systems to the auditory periphery. There are two middle ear muscles (MEMs): the stapedius and the tensor tympani. In man, the stapedius contracts in response to intense low frequency acoustic stimuli, exerting forces perpendicular to the stapes superstructure, increasing middle ear impedance and attenuating the intensity of sound energy reaching the inner ear (cochlea). The tensor tympani is believed to contract in response to self-generated noise (chewing, swallowing) and nonauditory stimuli. The MEM reflex pathways begin with sound presented to the ear. Transduction of sound occurs in the cochlea, resulting in an action potential that is transmitted along the auditory nerve to the cochlear nucleus in the brainstem (the first relay station for all ascending sound information originating in the ear). Unknown interneurons in the ventral cochlear nucleus project either directly or indirectly to MEM motoneurons located elsewhere in the brainstem. Motoneurons provide efferent innervation to the MEMs. Although the ascending and descending limbs of these reflex pathways have been well characterized, the identity of the reflex interneurons is not known, as are the source of modulatory inputs to these pathways. The aim of this article is to (a) provide an overview of MEM reflex anatomy and physiology, (b) present new data on MEM reflex anatomy and physiology from our laboratory and others, and (c) describe the clinical implications of our research. PMID:20870664

  15. Changes in nociceptive reflex facilitation during carrageenan-induced arthritis.

    PubMed

    Herrero, J F; Cervero, F

    1996-04-22

    Facilitation of neuronal responses induced by repetitive electrical stimulation of C-fibres (wind-up) is thought to be a substrate of hyperalgesia. There is little information on how these responses are in turn modified during hyperalgesia, and the extent to which hyperalgesic states also induce a facilitation of the neuronal responses mediated by A-fibres. The current study was undertaken in order to evaluate the effects of peripheral inflammation and stimulus presentation on the facilitation of nociceptive reflexes. Flexor reflexes, recorded as single motor units, were evoked in rats by cycles of low and high frequency electrical stimulation with pulse durations of 0.2, 0.5 and 2 ms. Responses were studied in control and inflammatory conditions, using the carrageenan-induced mono-arthritis model. The results show that the facilitation of late (C-fibre mediated) responses was proportional to the pulse duration of stimulation, as well as to the stimulation frequency. Facilitation was always higher when animals were subjected to inflammation. In inflammatory conditions, facilitation of reflexes was observed not only for late (C-fibre mediated) but also for early (A-fibre mediated) reflex responses. However, the facilitation of these early responses was not proportional to the intensity of stimulation. Thus, in arthritic animals, late (C-fibre mediated) flexion reflexes elicited from the skin, are facilitated and early (A-fibre mediated) reflexes are not only facilitated but, in addition, show a novel wind-up phenomenon.

  16. Non-linear boundary-layer receptivity due to distributed surface roughness

    NASA Technical Reports Server (NTRS)

    Amer, Tahani Reffet

    1995-01-01

    The process by which a laminar boundary layer internalizes the external disturbances in the form of instability waves is known as boundary-layer receptivity. The objective of the present research was to determine the effect of acoustic excitation on boundary-layer receptivity for a flat plate with distributed variable-amplitude surface roughness through measurements with a hot-wire probe. Tollmien-Schlichting mode shapes due to surface roughness receptivity have also been determined, analyzed, and shown to be in agreement with theory and other experimental work. It has been shown that there is a linear relationship between the surface roughness and receptivity for certain roughness configurations with constant roughness wavelength. In addition, strong non-linear receptivity effects exist for certain surface roughness configurations over a band where the surface roughness and T-S wavelength are matched. The results from the present experiment follow the trends predicted by theory and other experimental work for linear receptivity. In addition, the results show the existence of non-linear receptivity effects for certain combinations of surface roughness elements.

  17. Non-linear boundary-layer receptivity due to distributed surface roughness

    NASA Technical Reports Server (NTRS)

    Amer, Tahani Reffet; Selby, Gregory V.

    1995-01-01

    The process by which a laminar boundary layer internalizes the external disturbances in the form of instability waves is known as boundary-layer receptivity. The objective of the present research was to determine the effect of acoustic excitation on boundary-layer receptivity for a flat plate with distributed variable-amplitude surface roughness through measurements with a hot-wire probe. Tollmien-Schlichting (T-S) mode shapes due to surface-roughness receptivity have also been determined, analyzed, and shown to be in agreement with theory and other experimental work. It has been shown that there is a linear relationship between the surface roughness and receptivity for certain roughness configurations with constant roughness wavelength. In addition, strong nonlinear receptivity effects exist for certain surface roughness configurations over a band where the surface roughness and T-S wavelength are matched. The results from the present experiment follow the trends predicted by theory and other experimental work for linear receptivity. In addition, the results show the existence of nonlinear receptivity effects for certain combinations of surface roughness elements.

  18. Receptivity of Hypersonic Boundary Layers to Distributed Roughness and Acoustic Disturbances

    NASA Technical Reports Server (NTRS)

    Balakumar, Ponnampalam

    2012-01-01

    Boundary-layer receptivity and stability of Mach 6 flow over smooth and rough 7 half-angle sharp-tipped cones are numerically investigated. The receptivity of the boundary layer to slow acoustic disturbances, fast acoustic disturbances, and vortical disturbances are considered. The effects of two-dimensional isolated and distributed roughness on the receptivity and stability are also simulated. The results show that the instability waves are generated in the leading edge region and that the boundary layer is much more receptive to slow acoustic waves than to the fast waves. Vortical disturbances also generate unstable second modes, however the receptivity coefficients are smaller than that of the slow acoustic wave. An isolated two-dimensional roughness element of height h/delta =1/4 did not produce any difference in the receptivity or in the stability of the boundary layer. Distributed roughness elements produced a small decrease in the receptivity coefficient and also stabilized the boundary layer by small amounts.

  19. Receptivity of Hypersonic Boundary Layers to Distributed Roughness and Acoustic Disturbances

    NASA Technical Reports Server (NTRS)

    Balakumar, P.

    2013-01-01

    Boundary-layer receptivity and stability of Mach 6 flows over smooth and rough seven-degree half-angle sharp-tipped cones are numerically investigated. The receptivity of the boundary layer to slow acoustic disturbances, fast acoustic disturbances, and vortical disturbances is considered. The effects of three-dimensional isolated roughness on the receptivity and stability are also simulated. The results for the smooth cone show that the instability waves are generated in the leading edge region and that the boundary layer is much more receptive to slow acoustic waves than to the fast acoustic waves. Vortical disturbances also generate unstable second modes, however the receptivity coefficients are smaller than that of the slow acoustic wave. Distributed roughness elements located near the nose region decreased the receptivity of the second mode generated by the slow acoustic wave by a small amount. Roughness elements distributed across the continuous spectrum increased the receptivity of the second mode generated by the slow and fast acoustic waves and the vorticity wave. The largest increase occurred for the vorticity wave. Roughness elements distributed across the synchronization point did not change the receptivity of the second modes generated by the acoustic waves. The receptivity of the second mode generated by the vorticity wave increased in this case, but the increase is lower than that occurred with the roughness elements located across the continuous spectrum. The simulations with an isolated roughness element showed that the second mode waves generated by the acoustic disturbances are not influenced by the small roughness element. Due to the interaction, a three-dimensional wave is generated. However, the amplitude is orders of magnitude smaller than the two-dimensional wave.

  20. Crossed reflex reversal during human locomotion.

    PubMed

    Gervasio, Sabata; Farina, Dario; Sinkjær, Thomas; Mrachacz-Kersting, Natalie

    2013-05-01

    During human walking, precise coordination between the two legs is required in order to react promptly to any sudden hazard that could threaten stability. The networks involved in this coordination are not yet completely known, but a direct spinal connection between soleus (SOL) muscles has recently been revealed. For this response to be functional, as previously suggested, we hypothesize that it will be accompanied by a reaction in synergistic muscles, such as gastrocnemius lateralis (GL), and that a reversal of the response would occur when an opposite reaction is required. In the present study, surface EMGs of contralateral SOL and GL were analyzed after tibial nerve (TN), sural nerve (SuN), and medial plantar nerve (MpN) stimulation during two tasks in which opposite reactions are functionally expected: normal walking (NW), just before ipsilateral heel strike, and hybrid walking (HW) (legs walking in opposite directions), at ipsilateral push off and contralateral touchdown. Early crossed facilitations were observed in the contralateral GL after TN stimulation during NW, and a reversal of such responses occurred during HW. These results underline the functional significance of short-latency crossed responses and represent the first evidence for short-latency reflex reversal in the contralateral limb for humans. Muscle afferents seem to mediate the response during NW, while during HW cutaneous afferents are likely involved. It is thus possible that different afferents mediate the crossed response during different tasks.

  1. Reflex anuria affecting both kidneys following hysterectomy.

    PubMed

    Gholyaf, Mahmoud; Afzali, Saeed; Babolhavaegi, Hoshang; Rahimi, Abolfazl; Wagharseyedayn, Seyed A

    2009-01-01

    In situations when there is unilateral ureteral obstruction, the contralateral kidney retains its normal function. In rare instances however, it has been reported that unilateral ureteral obstruction can lead to reflex anuria (RA) and acute renal failure (ARF). Even more unusually, RA with ARF can occur without organic obstruction due to ureteric manipulation during pelvic surgery. We report a 78- year-old woman, who underwent hysterectomy because of endometrial carcinoma. She developed ARF evidenced by anuria of 120-hours duration, and gradual rise of serum creatinine levels to 11.8 mg/dL on the fifth day after hysterectomy. Ultrasound study of the urinary tract revealed bilateral moderate hydronephrosis. Detailed evaluation did not reveal any organic obstruction. She was managed with hemodialysis, control of hypertension and correction of fluid and electrolyte imbalances. By the sixth day, diuresis was established, and the blood urea and serum creatinine levels decreased to normal by the sixteenth day. The patient was finally discharged on the eighteenth day. Our case suggests that urologists and nephrologists should consider RA as one of the causes of anuria and ARF.

  2. Impaired Sacculocollic Reflex in Lateral Medullary Infarction

    PubMed Central

    Kim, Seonhye; Kim, Hyo-Jung; Kim, Ji Soo

    2011-01-01

    Objective: The aim of this study was to determine saccular dysfunction by measuring cervical vestibular-evoked myogenic potentials (cVEMP) and to correlate abnormality of cVEMP with results of other vestibular function tests in lateral medullary infarction (LMI). Methods: We recorded cVEMP in 21 patients with LMI documented on MRI. cVEMP was induced by a short tone burst and was recorded in contracting sternocleidomastoid muscle while patients turned their heads forcefully to the contralateral side against resistance. Patients also underwent video-oculographic recording of spontaneous, gaze-evoked and head shaking nystagmus (HSN), evaluation of ocular tilt reaction (OTR), measurement of the subjective visual vertical (SVV) tilt, bithermal caloric tests, and audiometry. Results: Nine patients (43%) showed abnormal cVEMP, unilateral in seven and bilateral in two. The cVEMP abnormalities included decreased p13–n23 amplitude in four, delayed p13/n23 responses in five, and both decreased and delayed responses in two. The abnormal cVEMP was ipsilesional in five, contralesional in two, and bilateral in two. The prevalence of OTR/SVV tilt, spontaneous nystagmus, and HSN did not differ between the patients with normal and abnormal cVEMP. Conclusion: cVEMP was abnormal in approximately half of the patients with LMI. The abnormal cVEMP indicates damage to the descending sacculocollic reflex pathway or disruption of commissural modulation between the vestibular nuclei. PMID:21415908

  3. Compensatory adrenal growth - A neurally mediated reflex

    NASA Technical Reports Server (NTRS)

    Dallman, M. F.; Engeland, W. C.; Shinsako, J.

    1976-01-01

    The responses of young rats to left adrenalectomy or left adrenal manipulation were compared to surgical sham adrenalectomy in which adrenals were observed but not touched. At 12 h right adrenal wet weight, dry weight, DNA, RNA, and protein content were increased (P less than 0.05) after the first two operations. Left adrenal manipulation resulted in increased right adrenal weight at 12 h but no change in left adrenal weight. Sequential manipulation of the left adrenal at time 0 and the right adrenal at 12 h resulted in an enlarged right adrenal at 12 h (P less than 0.01), and an enlarged left adrenal at 24 h (P less than 0.05), showing that the manipulated gland was capable of response. Bilateral adrenal manipulation of the adrenal glands resulted in bilateral enlargement of 12 h (P less than 0.01). Taken together with previous results, these findings strongly suggest that compensatory adrenal growth is a neurally mediated reflex.

  4. Vestibuloocular reflex of rhesus monkeys after spaceflight

    NASA Technical Reports Server (NTRS)

    Cohen, Bernard; Kozlovskaia, Inessa; Raphan, Theodore; Solomon, David; Helwig, Denice; Cohen, Nathaniel; Sirota, Mikhail; Iakushin, Sergei

    1992-01-01

    The vestibuloocular reflex (VOR) of two rhesus monkeys was recorded before and after 14 days of spaceflight. The gain (eye velocity/head velocity) of the horizontal VOR, tested 15 and 18 h after landing, was approximately equal to preflight values. The dominant time constant of the animal tested 15 h after landing was equivalent to that before flight. During nystagmus induced by off-vertical axis rotation (OVAR), the latency, rising time constant, steady-state eye velocity, and phase of modulation in eye velocity and eye position with respect to head position were similar in both monkeys before and after flight. There were changes in the amplitude of modulation of horizontal eye velocity during steady-state OVAR and in the ability to discharge stored activity rapidly by tilting during postrotatory nystagmus (tilt dumping) after flight: OVAR modulations were larger, and tilt dumping was lost in the one animal tested on the day of landing and for several days thereafter. If the gain and time constant of the horizontal VOR exchange in microgravity, they must revert to normal soon after landing. The changes that were observed suggest that adaptation to microgravity had caused alterations in way that the central nervous system processes otolith input.

  5. Artificial balancer - supporting device for postural reflex.

    PubMed

    Wojtara, Tytus; Sasaki, Makoto; Konosu, Hitoshi; Yamashita, Masashi; Shimoda, Shingo; Alnajjar, Fady; Kimura, Hidenori

    2012-02-01

    The evolutionarily novel ability to keep ones body upright while standing or walking, the human balance, deteriorates in old age or can be compromised after accidents or brain surgeries. With the aged society, age related balance problems are on the rise. Persons with balance problems are more likely to fall during their everyday life routines. Especially in elderly, falls can lead to bone fractures making the patient bedridden, weakening the body and making it more prone to other diseases. Health care expenses for a fall patient are often very high. There is a great deal of research being done on exoskeletons and power assists. However, these technologies concentrate mainly on the amplifications of human muscle power while balance has to be provided by the human themself. Our research has been focused on supporting human balance in harmony with the human's own posture control mechanisms such as postural reflexes. This paper proposes an artificial balancer that supports human balance through acceleration of a flywheel attached to the body. Appropriate correcting torques are generated through our device based on the measurements of body deflections. We have carried out experiments with test persons standing on a platform subject to lateral perturbations and ambulatory experiments while walking on a balance beam. These experiments have demonstrated the effectiveness of our device in supporting balance and the possibility of enhancing balance-keeping capability in human beings through the application of external torque. PMID:22169384

  6. The etiology of diverse receptive language skills at 12 years

    PubMed Central

    Dale, Philip S.; Harlaar, Nicole; Hayiou-Thomas, Marianna E.; Plomin, Robert

    2014-01-01

    Purpose In the second decade of life, language skills expand in both quantitative and qualitative ways. The etiology of these new skills and the relationships among them have been little explored. Method Taking advantage of widespread access to inexpensive and fast Internet connections in the United Kingdom, we administered four web-based measures of receptive language development – Vocabulary, Listening Grammar, Figurative Language, and Making Inferences – to a sample of 4892 12-year-old twin pairs participating in the Twins’ Early Development Study (TEDS). Results The four measures showed moderate phenotypic intercorrelation. All four showed moderate genetic influence (a2 between .25 and .36), and low shared environmental influence (c2 between .13 and .19). The median genetic correlation among the four measures was 0.87, indicating strong genetic overlap among them. A latent factor score for language, based on the common variance among the measures, showed substantial genetic influence (a2 = .59) and moderate shared environmental influence (c2 = .28). A small but significant sex difference favored females on the Listening Grammar and Making Inferences tests, but there was no evidence for sex differences in the etiology of any of the measures. Conclusion Despite the emergence of new skills at this developmental period, from the etiological perspective language skills remain relatively undifferentiated at an etiological level.. PMID:20605943

  7. Pinniped bioacoustics: Atmospheric and hydrospheric signal production, reception, and function

    NASA Astrophysics Data System (ADS)

    Schusterman, Ronald J.; Kastak, David; Reichmuth Kastak, Colleen; Holt, Marla; Southall, Brandon L.

    2001-05-01

    There is no convincing evidence that any of the 33 pinniped species evolved acoustic specializations for echolocation. However, all species produce and localize signals amphibiously in different communicative contexts. In the setting of sexual selection, aquatic mating male phocids and walruses tend to emit underwater calls, while male otariids and phocids that breed terrestrially emit airborne calls. Signature vocalizations are widespread among pinnipeds. There is evidence that males use signature threat calls, and it is possible that vocal recognition may be used by territorial males to form categories consisting of neighbors and strangers. In terms of mother-offspring recognition, both otariid females and their pups use acoustical cues for mutual recognition. In contrast, reunions between phocid females and their dependent pups depend mostly on pup vocalizations. In terms of signal reception, audiometric studies show that otariids are highly sensitive to aerial sounds but slightly less sensitive to underwater sounds. Conversely, except for deep-diving elephant seals, phocids are quite sensitive to acoustic signals both in air and under water. Finally, despite differences in absolute hearing sensitivity, pinnipeds have similar masked hearing capabilities in both media, supporting the notion that cochlear mechanics determine the effects of noise on hearing.

  8. Select interneuron clusters determine female sexual receptivity in Drosophila

    PubMed Central

    Sakurai, Akira; Koganezawa, Masayuki; Yasunaga, Kei-ichiro; Emoto, Kazuo; Yamamoto, Daisuke

    2013-01-01

    Female Drosophila with the spinster mutation repel courting males and rarely mate. Here we show that the non-copulating phenotype can be recapitulated by the elimination of spinster functions from either spin-A or spin-D neuronal clusters, in the otherwise wild-type (spinster heterozygous) female brain. Spin-D corresponds to the olfactory projection neurons with dendrites in the antennal lobe VA1v glomerulus that is fruitless-positive, sexually dimorphic and responsive to fly odour. Spin-A is a novel local neuron cluster in the suboesophageal ganglion, which is known to process contact chemical pheromone information and copulation-related signals. A slight reduction in spinster expression to a level with a minimal effect is sufficient to shut off female sexual receptivity if the dominant-negative mechanistic target of rapamycin is simultaneously expressed, although the latter manipulation alone has only a marginal effect. We propose that spin-mediated mechanistic target of rapamycin signal transduction in these neurons is essential for females to accept the courting male. PMID:23652013

  9. Unusual inflammation in gynecologic pathology associated with defective endometrial receptivity.

    PubMed

    Kitaya, Kotaro; Yasuo, Tadahiro; Tada, Yoshihiro; Hayashi, Terumi; Iwaki, Yuri; Karita, Masako; Funabiki, Miyako; Taguchi, Sagiri; Spillers, Dustin; Nakamura, Yoshitaka; Yamada, Hisao

    2014-09-01

    Human cycling endometrium displays a series of periodic transitions unique to this mucosal tissue, which includes rapid proliferation, secretory transformation, physiological angiogenesis, interstitial edema, and menstrual shedding. Among these properties of the endometrium are the inflammatory changes that occur dynamically across the menstrual cycle. Immunocompetent cell composition and inflammatory gene expression pattern in the human endometrium drastically fluctuate from the proliferative phase to the secretory phase, particularly at the time of ovulation. These local immune responses are fine-tuned by the direct or indirect action of two representative ovarian steroids, estradiol and progesterone, and are essential for successful blastocyst implantation. Meanwhile, studies have been accumulating the evidence that such physiological endometrial inflammatory status is altered in the presence of certain gynecologic pathologies. Given that blastocysts are semi-allografts for maternal tissue, even subtle alterations in endometrial immunity potentially have a negative impact on implantation process. In this article, we aimed to review and discuss the physiological and pathological mucosal inflammatory conditions that can affect endometrial receptivity. PMID:24771248

  10. Public Reception of Climate Science: Coherence, Reliability, and Independence.

    PubMed

    Hahn, Ulrike; Harris, Adam J L; Corner, Adam

    2016-01-01

    Possible measures to mitigate climate change require global collective actions whose impacts will be felt by many, if not all. Implementing such actions requires successful communication of the reasons for them, and hence the underlying climate science, to a degree that far exceeds typical scientific issues which do not require large-scale societal response. Empirical studies have identified factors, such as the perceived level of consensus in scientific opinion and the perceived reliability of scientists, that can limit people's trust in science communicators and their subsequent acceptance of climate change claims. Little consideration has been given, however, to recent formal results within philosophy concerning the relationship between truth, the reliability of evidence sources, the coherence of multiple pieces of evidence/testimonies, and the impact of (non-)independence between sources of evidence. This study draws on these results to evaluate exactly what has (and, more important, has not yet) been established in the empirical literature about the factors that bias the public's reception of scientific communications about climate change. PMID:26705767

  11. Receptive range analysis of a mouse odorant receptor subfamily

    PubMed Central

    Li, Jingyi; Haddad, Rafi; Santos, Vanessa; Bavan, Selvan; Luetje, Charles W.

    2015-01-01

    Mammals deploy a large array of odorant receptors (ORs) to detect and distinguish a vast number of odorant molecules. ORs vary widely in the type of odorant structures recognized and in the breadth of molecular receptive range (MRR), with some ORs recognizing a small group of closely related molecules and other ORs recognizing a wide range of structures. While closely related ORs have been shown to have similar MRRs, the functional relationships among less closely related ORs are unclear. We screened a small group of ORs with a diverse odorant panel to identify a new odorant-OR pairing (unsaturated aldehydes and MOR263-3). We then extensively screened MOR263-3 and a series of additional MORs related to MOR263-3 in various ways. MORs related by phylogenetic analysis (several other members of the MOR263 subfamily) had MRRs that overlapped with the MRR of MOR263-3, even with amino acid identity as low as 48% (MOR263-2). MOR171-17, predicted to be functionally related to MOR263-3 by an alternative bioinformatic analysis, but with only 39% amino acid identity, had a distinct odorant specificity. Our results support the use of phylogenetic analysis to predict functional relationships among ORs with relatively low amino acid identity. PMID:25772782

  12. Problem Internet Overuse Behaviors in College Students: Readiness-to-Change and Receptivity to Treatment.

    PubMed

    O'Brien, Jennifer E; Li, Wen; Snyder, Susan M; Howard, Matthew O

    2016-01-01

    This mixed methods study explores college students' readiness-to-change and receptivity to treatment for problem Internet overuse behaviors. Focus groups were conducted with 27 college students who self-identified as Internet over-users, and had experienced biopsychosocial problems related to Internet overuse. Participants completed standardized questionnaires assessing their Internet use and sociodemographic forms. Focus groups explored readiness to change problem Internet overuse behaviors and receptivity to treatment. Similar to college students with other addictive behaviors, students with problem Internet overuse fall along a continuum vis-à-vis readiness-to-change their behaviors. Over half of the participants were receptive to treatment for their problem Internet overuse behaviors.

  13. Hyperekplexia and stiff-man syndrome: abnormal brainstem reflexes suggest a physiological relationship

    PubMed Central

    Khasani, S; Becker, K; Meinck, H

    2004-01-01

    Background and objectives: Hyperekplexia and the stiff-man syndrome (SMS) are both conditions with exaggerated startle suggesting abnormal brainstem function. Investigation of brainstem reflexes may provide insight into disturbed reflex excitation and inhibition underlying these movement disorders. Patients and methods: Using four-channel EMG, we examined four trigeminal brainstem reflexes (monosynaptic masseter, masseter inhibitory, glabella, and orbicularis oculi blink reflexes) and their spread into pericranial muscles in five patients with familial hyperekplexia (FH), two with acquired hyperekplexia (AH), 10 with SMS, and 15 healthy control subjects. Results: Both FH/AH and SMS patients had abnormal propagation of brainstem reflexes into pericranial muscles. All patients with hyperekplexia showed an abnormal short-latency (15–20 ms) reflex in the trapezius muscle with a characteristic clinical appearance ("head retraction jerk") evoked by tactile or electrical stimulation of the trigeminal nerve, but normal monosynaptic masseter reflexes. Inhibitory brainstem reflexes were attenuated in some FH/AH patients. Four of 10 patients with SMS had similar short-latency reflexes in the neck muscles and frequently showed widespread enhancement of other excitatory reflexes, reflex spasms, and attenuation of inhibitory brainstem reflexes. Conclusion: Reflex excitation is exaggerated and inhibition is attenuated in both stiff-man syndrome and familial or acquired hyperekplexia, indicating a physiological relationship. Reflex transmission in the brainstem appears biased towards excitation which may imply dysfunction of inhibitory glycinergic or GABAergic interneurons, or both. PMID:15314112

  14. ESO Reflex: a graphical workflow engine for data reduction

    NASA Astrophysics Data System (ADS)

    Hook, Richard; Ullgrén, Marko; Romaniello, Martino; Maisala, Sami; Oittinen, Tero; Solin, Otto; Savolainen, Ville; Järveläinen, Pekka; Tyynelä, Jani; Péron, Michèle; Ballester, Pascal; Gabasch, Armin; Izzo, Carlo

    ESO Reflex is a prototype software tool that provides a novel approach to astronomical data reduction by integrating a modern graphical workflow system (Taverna) with existing legacy data reduction algorithms. Most of the raw data produced by instruments at the ESO Very Large Telescope (VLT) in Chile are reduced using recipes. These are compiled C applications following an ESO standard and utilising routines provided by the Common Pipeline Library (CPL). Currently these are run in batch mode as part of the data flow system to generate the input to the ESO/VLT quality control process and are also exported for use offline. ESO Reflex can invoke CPL-based recipes in a flexible way through a general purpose graphical interface. ESO Reflex is based on the Taverna system that was originally developed within the UK life-sciences community. Workflows have been created so far for three VLT/VLTI instruments, and the GUI allows the user to make changes to these or create workflows of their own. Python scripts or IDL procedures can be easily brought into workflows and a variety of visualisation and display options, including custom product inspection and validation steps, are available. Taverna is intended for use with web services and experiments using ESO Reflex to access Virtual Observatory web services have been successfully performed. ESO Reflex is the main product developed by Sampo, a project led by ESO and conducted by a software development team from Finland as an in-kind contribution to joining ESO. The goal was to look into the needs of the ESO community in the area of data reduction environments and to create pilot software products that illustrate critical steps along the road to a new system. Sampo concluded early in 2008. This contribution will describe ESO Reflex and show several examples of its use both locally and using Virtual Observatory remote web services. ESO Reflex is expected to be released to the community in early 2009.

  15. Can Treadmill Perturbations Evoke Stretch Reflexes in the Calf Muscles?

    PubMed Central

    Sloot, Lizeth H.; van den Noort, Josien C.; van der Krogt, Marjolein M.; Bruijn, Sjoerd M.; Harlaar, Jaap

    2015-01-01

    Disinhibition of reflexes is a problem amongst spastic patients, for it limits a smooth and efficient execution of motor functions during gait. Treadmill belt accelerations may potentially be used to measure reflexes during walking, i.e. by dorsal flexing the ankle and stretching the calf muscles, while decelerations show the modulation of reflexes during a reduction of sensory feedback. The aim of the current study was to examine if belt accelerations and decelerations of different intensities applied during the stance phase of treadmill walking can evoke reflexes in the gastrocnemius, soleus and tibialis anterior in healthy subjects. Muscle electromyography and joint kinematics were measured in 10 subjects. To determine whether stretch reflexes occurred, we assessed modelled musculo-tendon length and stretch velocity, the amount of muscle activity, as well as the incidence of bursts or depressions in muscle activity with their time delays, and co-contraction between agonist and antagonist muscle. Although the effect on the ankle angle was small with 2.8±1.0°, the perturbations caused clear changes in muscle length and stretch velocity relative to unperturbed walking. Stretched muscles showed an increasing incidence of bursts in muscle activity, which occurred after a reasonable electrophysiological time delay (163–191 ms). Their amplitude was related to the muscle stretch velocity and not related to co-contraction of the antagonist muscle. These effects increased with perturbation intensity. Shortened muscles showed opposite effects, with a depression in muscle activity of the calf muscles. The perturbations only slightly affected the spatio-temporal parameters, indicating that normal walking was retained. Thus, our findings showed that treadmill perturbations can evoke reflexes in the calf muscles and tibialis anterior. This comprehensive study could form the basis for clinical implementation of treadmill perturbations to functionally measure reflexes during

  16. Can Treadmill Perturbations Evoke Stretch Reflexes in the Calf Muscles?

    PubMed

    Sloot, Lizeth H; van den Noort, Josien C; van der Krogt, Marjolein M; Bruijn, Sjoerd M; Harlaar, Jaap

    2015-01-01

    Disinhibition of reflexes is a problem amongst spastic patients, for it limits a smooth and efficient execution of motor functions during gait. Treadmill belt accelerations may potentially be used to measure reflexes during walking, i.e. by dorsal flexing the ankle and stretching the calf muscles, while decelerations show the modulation of reflexes during a reduction of sensory feedback. The aim of the current study was to examine if belt accelerations and decelerations of different intensities applied during the stance phase of treadmill walking can evoke reflexes in the gastrocnemius, soleus and tibialis anterior in healthy subjects. Muscle electromyography and joint kinematics were measured in 10 subjects. To determine whether stretch reflexes occurred, we assessed modelled musculo-tendon length and stretch velocity, the amount of muscle activity, as well as the incidence of bursts or depressions in muscle activity with their time delays, and co-contraction between agonist and antagonist muscle. Although the effect on the ankle angle was small with 2.8±1.0°, the perturbations caused clear changes in muscle length and stretch velocity relative to unperturbed walking. Stretched muscles showed an increasing incidence of bursts in muscle activity, which occurred after a reasonable electrophysiological time delay (163-191 ms). Their amplitude was related to the muscle stretch velocity and not related to co-contraction of the antagonist muscle. These effects increased with perturbation intensity. Shortened muscles showed opposite effects, with a depression in muscle activity of the calf muscles. The perturbations only slightly affected the spatio-temporal parameters, indicating that normal walking was retained. Thus, our findings showed that treadmill perturbations can evoke reflexes in the calf muscles and tibialis anterior. This comprehensive study could form the basis for clinical implementation of treadmill perturbations to functionally measure reflexes during

  17. Trigeminal Cardiac Reflex and Cerebral Blood Flow Regulation

    PubMed Central

    Lapi, Dominga; Scuri, Rossana; Colantuoni, Antonio

    2016-01-01

    The stimulation of some facial regions is known to trigger the trigemino-cardiac reflex: the main stimulus is represented by the contact of the face with water. This phenomenon called diving reflex induces a set of reactions in the cardiovascular and respiratory systems occurring in all mammals, especially marine (whales, seals). During the immersion of the face in the water, the main responses are aimed at reducing the oxygen consumption of the organism. Accordingly reduction in heart rate, peripheral vasoconstriction, blood pooling in certain organs, especially the heart, and brain and an increase in blood pressure have been reported. Moreover, the speed and intensity of the reflex is inversely proportional to the temperature of the water: more cold the water, more reactions as described are strong. In the case of deep diving an additional effect, such as blood deviation, has been reported: the blood is sequestered within the lungs, to compensate for the increase in the external pressure, preventing them from collapsing. The trigeminal-cardiac reflex is not just confined to the diving reflex; recently it has been shown that a brief proprioceptive stimulation (10 min) by jaw extension in rats produces interesting effects both at systemic and cerebral levels, reducing the arterial blood pressure, and vasodilating the pial arterioles. The arteriolar dilation is associated with rhythmic diameter changes characterized by an increase in the endothelial activity. Fascinating the stimulation of trigeminal nerve is able to activate the nitric oxide release by vascular endothelial cells. Therefore, the aim of this review was to highlight the effects due to trigeminal cardiac reflex induced by a simple mandibular extension. Opposite effects, such as hypotension, and modulation of cerebral arteriolar tone, were observed, when these responses were compared to those elicited by the diving reflex. PMID:27812317

  18. Avian reflex and electroencephalogram responses in different states of consciousness.

    PubMed

    Sandercock, Dale A; Auckburally, Adam; Flaherty, Derek; Sandilands, Victoria; McKeegan, Dorothy E F

    2014-06-22

    Defining states of clinical consciousness in animals is important in veterinary anaesthesia and in studies of euthanasia and welfare assessment at slaughter. The aim of this study was to validate readily observable reflex responses in relation to different conscious states, as confirmed by EEG analysis, in two species of birds under laboratory conditions (35-week-old layer hens (n=12) and 11-week-old turkeys (n=10)). We evaluated clinical reflexes and characterised electroencephalograph (EEG) activity (as a measure of brain function) using spectral analyses in four different clinical states of consciousness: conscious (fully awake), semi-conscious (sedated), unconscious-optimal (general anaesthesia), unconscious-sub optimal (deep hypnotic state), as well as assessment immediately following euthanasia. Jaw or neck muscle tone was the most reliable reflex measure distinguishing between conscious and unconscious states. Pupillary reflex was consistently observed until respiratory arrest. Nictitating membrane reflex persisted for a short time (<1 min) after respiratory arrest and brain death (isoelectric EEG). The results confirm that the nictitating membrane reflex is a conservative measure of death in poultry. Using spectral analyses of the EEG waveforms it was possible to readily distinguish between the different states of clinical consciousness. In all cases, when birds progressed from a conscious to unconscious state; total spectral power (PTOT) significantly increased, whereas median (F50) and spectral edge (F95) frequencies significantly decreased. This study demonstrates that EEG analysis can differentiate between clinical states (and loss of brain function at death) in birds and provides a unique integration of reflex responses and EEG activity.

  19. Restoration of sensory and motor function in earthworm escape reflex pathways following ventral nerve cord transplantation.

    PubMed

    Vining, E P; Drewes, C D

    1985-07-01

    Twelve segments of earthworm ventral nerve cord (VNC) were excised from either segments 10-22 (i.e., within the MGF sensory field) or segments 75-87 (i.e., within the LGF sensory field) in donor worms and heterotopically, or homotopically, transplanted into recipient animals. Morphological evidence indicated that by four days after transplantation, peripheral connections were formed between the transplanted VNC and the body wall of the recipient, many of these connections involving novel pathways projecting ventrally from the transplant. Restoration of giant fiber touch sensitivity in the transplant occurred from 4-14 days after transplantation. Regardless of the site of transplantation, the restored sensitivity (i.e., MGF versus LGF sensory field) always reflected the origin of the donor VNC. Restoration of MGF-mediated motor activity in the transplant occurred approximately 17-22 days after transplantation. In the case of heterotopic transplants (i.e., anterior VNC into posterior segments), the restored MGF-mediated muscle potentials were facilitating, indicating at least some tendency for persistence of this feature after transplantation. Behavioral observations suggested that reconnections involving other reflex pathways (e.g., those controlling setal movements and peristaltic locomotion) were made within the transplant region and that properties of the restored reflexes reflected those of the donor VNC. The rapid restoration of sensory and motor connections, despite heterotopic placement, indicates a significant capacity for peripheral regeneration by the transplanted VNC. On the other hand, the maintenance of various properties of reflex function, despite heterotopic transplantation, suggests a limited capacity for rearrangement of established central connections in the transplanted VNC. PMID:4031850

  20. Driving a car using reflexive fuzzy behaviors

    SciTech Connect

    Pin, F.G.; Watanabe, Y.

    1992-01-01

    Vehicle control in a-priori unknown, unpredictable, and dynamic environments requires many calculational and reasoning schemes to operate on the basis of very imprecise, incomplete, or unreliable data. For such systems, in which all the uncertainties can not be engineered away, approximate reasoning may provide an alternative to the complexity and computational requirements of conventional uncertainty analysis and propagation techniques. Two types of computer boards including custom-designed VLSI chips have been developed to add a fuzzy inferencing capability to real-time control systems. All inferencing rules on a chip are processed in parallel, allowing execution of the entire rule base in about 30 [mu]sec, and therefore, making control of reflex-type'' of motions envisionable. The use of these boards and the approach using superposition of elemental sensor-based behaviors for the development of qualitative reasoning schemes emulating human-like navigation in a-prioii unknown environments are discussed. We describe how the human-like navigation scheme implemented on one of the qualitative inferencing boards was installed on a test-bed platform to investigate two control modes for driving a car in a-priori unknown environments on the basis of sparse and imprecise sensor data. In the first mode, the car navigates autonomously, while in the second mode, the system acts as a driver's aid providing the driver with linguistic (fuzzy) commands to turn left or right and speed up or slow down depending on the obstacles perceived by the sensors. Experiments with both modes of control are described in which the system uses only three acoustic range (sonar) sensor charmers to perceive the environment. Simulation results as well as indoor and outdoor experiments are discussed to illustrate the feasibility and robustness of autonomous navigation and/or safety enhancing driver's aid using the new fuzzy inferencing hardware system and some human-like reasoning schemes.