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Sample records for adapted visual functions

  1. Adaptive tuning functions arise from visual observation of past movement

    PubMed Central

    Howard, Ian S.; Franklin, David W.

    2016-01-01

    Visual observation of movement plays a key role in action. For example, tennis players have little time to react to the ball, but still need to prepare the appropriate stroke. Therefore, it might be useful to use visual information about the ball trajectory to recall a specific motor memory. Past visual observation of movement (as well as passive and active arm movement) affects the learning and recall of motor memories. Moreover, when passive or active, these past contextual movements exhibit generalization (or tuning) across movement directions. Here we extend this work, examining whether visual motion also exhibits similar generalization across movement directions and whether such generalization functions can explain patterns of interference. Both the adaptation movement and contextual movement exhibited generalization beyond the training direction, with the visual contextual motion exhibiting much broader tuning. A second experiment demonstrated that this pattern was consistent with the results of an interference experiment where opposing force fields were associated with two separate visual movements. Overall, our study shows that visual contextual motion exhibits much broader (and shallower) tuning functions than previously seen for either passive or active movements, demonstrating that the tuning characteristics of past motion are highly dependent on their sensory modality. PMID:27341163

  2. Visual Adaptation

    PubMed Central

    Webster, Michael A.

    2015-01-01

    Sensory systems continuously mold themselves to the widely varying contexts in which they must operate. Studies of these adaptations have played a long and central role in vision science. In part this is because the specific adaptations remain a powerful tool for dissecting vision, by exposing the mechanisms that are adapting. That is, “if it adapts, it's there.” Many insights about vision have come from using adaptation in this way, as a method. A second important trend has been the realization that the processes of adaptation are themselves essential to how vision works, and thus are likely to operate at all levels. That is, “if it's there, it adapts.” This has focused interest on the mechanisms of adaptation as the target rather than the probe. Together both approaches have led to an emerging insight of adaptation as a fundamental and ubiquitous coding strategy impacting all aspects of how we see. PMID:26858985

  3. Neuropsychological presentation and adaptive skills in high-functioning adolescents with visual impairment: A preliminary investigation.

    PubMed

    Greenaway, R; Pring, L; Schepers, A; Isaacs, D P; Dale, N J

    2017-01-01

    Studies in infants and young children with congenital visual impairment (VI) have indicated early developmental vulnerabilities, conversely research with older children and adults have highlighted areas of cognitive strength. A minimal amount is known, however, about the possible combination of strengths and weaknesses in adolescence, and this present study therefore aims to explore the neuropsychological presentation and adaptive behavior profile in high-functioning adolescents with congenital VI. Participants completed a battery of commonly used neuropsychological measures assessing memory, executive function, and attention. The measures utilized focused on auditory neuropsychological function, because only subtests that could be completed with auditory administration were suitable for this sample. Parents completed standardized measures of adaptive behavior, executive function, and social communication. Compared to aged-based norms for normal sight, adolescents with VI demonstrated strengths in aspects of working memory and verbal memory. Furthermore, performance across the neuropsychological battery was within or above the average range for the majority of the sample. In contrast, parent-report measures indicated areas of weakness in adaptive functioning, social communication, and behavioral executive functioning. Overall, this study provides preliminary evidence that relative to fully sighted peers, high-functioning adolescents with VI present with an uneven profile of cognitive and adaptive skills, which has important implications for assessment and intervention.

  4. The Association of Intelligence, Visual-Motor Functioning, and Personality Characteristics With Adaptive Behavior in Individuals With Williams Syndrome.

    PubMed

    Fu, Trista J; Lincoln, Alan J; Bellugi, Ursula; Searcy, Yvonne M

    2015-07-01

    Williams syndrome (WS) is associated with deficits in adaptive behavior and an uneven adaptive profile. This study investigated the association of intelligence, visual-motor functioning, and personality characteristics with the adaptive behavior in individuals with WS. One hundred individuals with WS and 25 individuals with developmental disabilities of other etiologies were included in this study. This study found that IQ and visual-motor functioning significantly predicted adaptive behavior in individuals of WS. Visual-motor functioning especially predicted the most amount of unique variance in overall adaptive behavior and contributed to the variance above and beyond that of IQ. Present study highlights the need for interventions that address visual-motor and motor functioning in individuals with WS.

  5. Functional magnetic resonance imaging adaptation reveals a noncategorical representation of hue in early visual cortex

    PubMed Central

    Persichetti, Andrew S.; Thompson-Schill, Sharon L.; Butt, Omar H.; Brainard, David H.; Aguirre, Geoffrey K.

    2015-01-01

    Color names divide the fine-grained gamut of color percepts into discrete categories. A categorical transition must occur somewhere between the initial encoding of the continuous spectrum of light by the cones and the verbal report of the name of a color stimulus. Here, we used a functional magnetic resonance imaging (fMRI) adaptation experiment to examine the representation of hue in the early visual cortex. Our stimuli varied in hue between blue and green. We found in the early visual areas (V1, V2/3, and hV4) a smoothly increasing recovery from adaptation with increasing hue distance between adjacent stimuli during both passive viewing (Experiment 1) and active categorization (Experiment 2). We examined the form of the adaptation effect and found no evidence that a categorical representation mediates the release from adaptation for stimuli that cross the blue–green color boundary. Examination of the direct effect of stimulus hue on the fMRI response did, however, reveal an enhanced response to stimuli near the blue–green category border. This was largest in hV4 and when subjects were engaged in active categorization of the stimulus hue. In contrast with a recent report from another laboratory (Bird, Berens, Horner, & Franklin, 2014), we found no evidence for a categorical representation of color in the middle frontal gyrus. A post hoc whole-brain analysis, however, revealed several regions in the frontal cortex with a categorical effect in the adaptation response. Overall, our results support the idea that the representation of color in the early visual cortex is primarily fine grained and does not reflect color categories. PMID:26024465

  6. Visual Perception versus Visual Function.

    ERIC Educational Resources Information Center

    Lieberman, Laurence M.

    1984-01-01

    Disfunctions are drawn between visual perception and visual function, and four optometrists respond with further analysis of the visual perception-visual function controversy and its implications for children with learning problems. (CL)

  7. Habituation of visual adaptation

    PubMed Central

    Dong, Xue; Gao, Yi; Lv, Lili; Bao, Min

    2016-01-01

    Our sensory system adjusts its function driven by both shorter-term (e.g. adaptation) and longer-term (e.g. learning) experiences. Most past adaptation literature focuses on short-term adaptation. Only recently researchers have begun to investigate how adaptation changes over a span of days. This question is important, since in real life many environmental changes stretch over multiple days or longer. However, the answer to the question remains largely unclear. Here we addressed this issue by tracking perceptual bias (also known as aftereffect) induced by motion or contrast adaptation across multiple daily adaptation sessions. Aftereffects were measured every day after adaptation, which corresponded to the degree of adaptation on each day. For passively viewed adapters, repeated adaptation attenuated aftereffects. Once adapters were presented with an attentional task, aftereffects could either reduce for easy tasks, or initially show an increase followed by a later decrease for demanding tasks. Quantitative analysis of the decay rates in contrast adaptation showed that repeated exposure of the adapter appeared to be equivalent to adaptation to a weaker stimulus. These results suggest that both attention and a non-attentional habituation-like mechanism jointly determine how adaptation develops across multiple daily sessions. PMID:26739917

  8. Visual adaptation and face perception

    PubMed Central

    Webster, Michael A.; MacLeod, Donald I. A.

    2011-01-01

    The appearance of faces can be strongly affected by the characteristics of faces viewed previously. These perceptual after-effects reflect processes of sensory adaptation that are found throughout the visual system, but which have been considered only relatively recently in the context of higher level perceptual judgements. In this review, we explore the consequences of adaptation for human face perception, and the implications of adaptation for understanding the neural-coding schemes underlying the visual representation of faces. The properties of face after-effects suggest that they, in part, reflect response changes at high and possibly face-specific levels of visual processing. Yet, the form of the after-effects and the norm-based codes that they point to show many parallels with the adaptations and functional organization that are thought to underlie the encoding of perceptual attributes like colour. The nature and basis for human colour vision have been studied extensively, and we draw on ideas and principles that have been developed to account for norms and normalization in colour vision to consider potential similarities and differences in the representation and adaptation of faces. PMID:21536555

  9. Visual adaptation dominates bimodal visual-motor action adaptation

    PubMed Central

    de la Rosa, Stephan; Ferstl, Ylva; Bülthoff, Heinrich H.

    2016-01-01

    A long standing debate revolves around the question whether visual action recognition primarily relies on visual or motor action information. Previous studies mainly examined the contribution of either visual or motor information to action recognition. Yet, the interaction of visual and motor action information is particularly important for understanding action recognition in social interactions, where humans often observe and execute actions at the same time. Here, we behaviourally examined the interaction of visual and motor action recognition processes when participants simultaneously observe and execute actions. We took advantage of behavioural action adaptation effects to investigate behavioural correlates of neural action recognition mechanisms. In line with previous results, we find that prolonged visual exposure (visual adaptation) and prolonged execution of the same action with closed eyes (non-visual motor adaptation) influence action recognition. However, when participants simultaneously adapted visually and motorically – akin to simultaneous execution and observation of actions in social interactions - adaptation effects were only modulated by visual but not motor adaptation. Action recognition, therefore, relies primarily on vision-based action recognition mechanisms in situations that require simultaneous action observation and execution, such as social interactions. The results suggest caution when associating social behaviour in social interactions with motor based information. PMID:27029781

  10. Saccade Adaptation and Visual Uncertainty

    PubMed Central

    Souto, David; Gegenfurtner, Karl R.; Schütz, Alexander C.

    2016-01-01

    Visual uncertainty may affect saccade adaptation in two complementary ways. First, an ideal adaptor should take into account the reliability of visual information for determining the amount of correction, predicting that increasing visual uncertainty should decrease adaptation rates. We tested this by comparing observers' direction discrimination and adaptation rates in an intra-saccadic-step paradigm. Second, clearly visible target steps may generate a slower adaptation rate since the error can be attributed to an external cause, instead of an internal change in the visuo-motor mapping that needs to be compensated. We tested this prediction by measuring saccade adaptation to different step sizes. Most remarkably, we found little correlation between estimates of visual uncertainty and adaptation rates and no slower adaptation rates with more visible step sizes. Additionally, we show that for low contrast targets backward steps are perceived as stationary after the saccade, but that adaptation rates are independent of contrast. We suggest that the saccadic system uses different position signals for adapting dysmetric saccades and for generating a trans-saccadic stable visual percept, explaining that saccade adaptation is found to be independent of visual uncertainty. PMID:27252635

  11. Cross-adaptation combined with TMS reveals a functional overlap between vision and imagery in the early visual cortex.

    PubMed

    Cattaneo, Zaira; Bona, Silvia; Silvanto, Juha

    2012-02-01

    The extent to which the generation of mental images draws on the neuronal representations involved in visual perception has been the subject of much debate. To investigate this overlap, we assessed whether adaptation to visual stimuli affects the ability to generate visual mental images; such cross-adaptation would indicate shared neural representations between visual perception and imagery. Mental imagery was tested using a modified version of the clock task, in which subjects are presented with a digital time (e.g. "2.15") and are asked to generate a mental image of the clock hands displaying this time on an empty clock face. Participants were adapted to oriented lines either on the upper or lower side of the clock face prior to the mental image generation. The results showed that mental imagery was impaired when the mental image had to be generated in the adapted region of visual space (Experiment 1). In Experiment 2, we used TMS to determine whether this adaptation effect occurs in the early visual cortex (EVC; V1/V2). Relative to control conditions (No TMS and Vertex TMS), EVC TMS facilitated mental imagery generation when the mental image spatially overlapped with the adapter. Our results thus show that neuronal representations in the EVC which encode (and are suppressed by) visual input play a causal role in visual mental imagery.

  12. Spectral Tuning of Killer Whale (Orcinus orca) Rhodopsin: Evidence for Positive Selection and Functional Adaptation in a Cetacean Visual Pigment.

    PubMed

    Dungan, Sarah Z; Kosyakov, Alexander; Chang, Belinda S W

    2016-02-01

    Cetaceans have undergone a remarkable evolutionary transition that was accompanied by many sensory adaptations, including modification of the visual system for underwater environments. Recent sequencing of cetacean genomes has made it possible to begin exploring the molecular basis of these adaptations. In this study we use in vitro expression methods to experimentally characterize the first step of the visual transduction cascade, the light activation of rhodopsin, for the killer whale. To investigate the spectral effects of amino acid substitutions thought to correspond with absorbance shifts relative to terrestrial mammals, we used the orca gene as a background for the first site-directed mutagenesis experiments in a cetacean rhodopsin. The S292A mutation had the largest effect, and was responsible for the majority of the spectral difference between killer whale and bovine (terrestrial) rhodopsin. Using codon-based likelihood models, we also found significant evidence for positive selection in cetacean rhodopsin sequences, including on spectral tuning sites we experimentally mutated. We then investigated patterns of ecological divergence that may be correlated with rhodopsin functional variation by using a series of clade models that partitioned the data set according to phylogeny, habitat, and foraging depth zone. Only the model partitioning according to depth was significant. This suggests that foraging dives might be a selective regime influencing cetacean rhodopsin divergence, and our experimental results indicate that spectral tuning may be playing an adaptive role in this process. Our study demonstrates that combining computational and experimental methods is crucial for gaining insight into the selection pressures underlying molecular evolution.

  13. Differential effect of visual motion adaption upon visual cortical excitability.

    PubMed

    Lubeck, Astrid J A; Van Ombergen, Angelique; Ahmad, Hena; Bos, Jelte E; Wuyts, Floris L; Bronstein, Adolfo M; Arshad, Qadeer

    2017-03-01

    The objectives of this study were 1) to probe the effects of visual motion adaptation on early visual and V5/MT cortical excitability and 2) to investigate whether changes in cortical excitability following visual motion adaptation are related to the degree of visual dependency, i.e., an overreliance on visual cues compared with vestibular or proprioceptive cues. Participants were exposed to a roll motion visual stimulus before, during, and after visual motion adaptation. At these stages, 20 transcranial magnetic stimulation (TMS) pulses at phosphene threshold values were applied over early visual and V5/MT cortical areas from which the probability of eliciting a phosphene was calculated. Before and after adaptation, participants aligned the subjective visual vertical in front of the roll motion stimulus as a marker of visual dependency. During adaptation, early visual cortex excitability decreased whereas V5/MT excitability increased. After adaptation, both early visual and V5/MT excitability were increased. The roll motion-induced tilt of the subjective visual vertical (visual dependence) was not influenced by visual motion adaptation and did not correlate with phosphene threshold or visual cortex excitability. We conclude that early visual and V5/MT cortical excitability is differentially affected by visual motion adaptation. Furthermore, excitability in the early or late visual cortex is not associated with an increase in visual reliance during spatial orientation. Our findings complement earlier studies that have probed visual cortical excitability following motion adaptation and highlight the differential role of the early visual cortex and V5/MT in visual motion processing.NEW & NOTEWORTHY We examined the influence of visual motion adaptation on visual cortex excitability and found a differential effect in V1/V2 compared with V5/MT. Changes in visual excitability following motion adaptation were not related to the degree of an individual's visual dependency.

  14. Functional Visual Loss

    PubMed Central

    Bruce, Beau B; Newman, Nancy J

    2010-01-01

    Synopsis Neurologists frequently evaluate patients complaining of vision loss, especially when the patient has been examined by an ophthalmologist who has found no ocular disease. A significant proportion of patients presenting to the neurologist with visual complaints will have non-organic or functional visual loss. While there are examination techniques which can aid in the detection and diagnosis of functional visual loss, the frequency with which functional visual loss occurs concomitantly with organic disease warrants substantial caution on the part of the clinician. Furthermore, purely functional visual loss is never a diagnosis of exclusion, and must be supported by positive findings on examination that demonstrate normal visual function. The relationship of true psychological disease and functional visual loss is unclear and most patients respond well to simple reassurance. PMID:20638000

  15. [Biological adaptation and immune status of preschool children with visual function disorders in conditions of preschool educational institutions of compensating type].

    PubMed

    Bannikova, L P; Koksharov, A V

    2013-01-01

    For implementation of a comprehensive approach in the elaboration of preventive and corrective measures in children with impaired visual function in conditions of preschool educational institutions of compensating type there were studied adaptation reserves of their organism, as well as indices of immune status. Biological adaptation was studied with the help ofcardiointervalography in 111 children aged 6-7years. With the use of ELISA 88 children were examined in terms of IgA, IgM, IgG, slgA in saliva.

  16. Binocular adaptive optics visual simulator.

    PubMed

    Fernández, Enrique J; Prieto, Pedro M; Artal, Pablo

    2009-09-01

    A binocular adaptive optics visual simulator is presented. The instrument allows for measuring and manipulating ocular aberrations of the two eyes simultaneously, while the subject performs visual testing under binocular vision. An important feature of the apparatus consists on the use of a single correcting device and wavefront sensor. Aberrations are controlled by means of a liquid-crystal-on-silicon spatial light modulator, where the two pupils of the subject are projected. Aberrations from the two eyes are measured with a single Hartmann-Shack sensor. As an example of the potential of the apparatus for the study of the impact of the eye's aberrations on binocular vision, results of contrast sensitivity after addition of spherical aberration are presented for one subject. Different binocular combinations of spherical aberration were explored. Results suggest complex binocular interactions in the presence of monochromatic aberrations. The technique and the instrument might contribute to the better understanding of binocular vision and to the search for optimized ophthalmic corrections.

  17. Adaptive optics without altering visual perception.

    PubMed

    Koenig, D E; Hart, N W; Hofer, H J

    2014-04-01

    Adaptive optics combined with visual psychophysics creates the potential to study the relationship between visual function and the retina at the cellular scale. This potential is hampered, however, by visual interference from the wavefront-sensing beacon used during correction. For example, we have previously shown that even a dim, visible beacon can alter stimulus perception (Hofer et al., 2012). Here we describe a simple strategy employing a longer wavelength (980nm) beacon that, in conjunction with appropriate restriction on timing and placement, allowed us to perform psychophysics when dark adapted without altering visual perception. The method was verified by comparing detection and color appearance of foveally presented small spot stimuli with and without the wavefront beacon present in 5 subjects. As an important caution, we found that significant perceptual interference can occur even with a subliminal beacon when additional measures are not taken to limit exposure. Consequently, the lack of perceptual interference should be verified for a given system, and not assumed based on invisibility of the beacon.

  18. Hybrid adaptive-optics visual simulator.

    PubMed

    Cánovas, Carmen; Prieto, Pedro M; Manzanera, Silvestre; Mira, Alejandro; Artal, Pablo

    2010-01-15

    We have developed a hybrid adaptive-optics visual simulator (HAOVS), combining two different phase-manipulation technologies: an optically addressed liquid-crystal phase modulator, relatively slow but capable of producing abrupt or discontinuous phase profiles; and a membrane deformable mirror, restricted to smooth profiles but with a temporal response allowing compensation of the eye's aberration fluctuations. As proof of concept, a phase element structured as discontinuous radial sectors was objectively tested as a function of defocus, and a correction loop was closed in a real eye. To further illustrate the capabilities of the device for visual simulation, we recorded extended images of different stimuli through the system by means of an external camera replacing the subject's eye. The HAOVS is specially intended as a tool for developing new ophthalmic optics elements, where it opens the possibility to explore designs with irregularities and/or discontinuities.

  19. VISUAL ADAPTATION AND CHEMISTRY OF THE RODS

    PubMed Central

    Wald, George; Clark, Anna-Betty

    1937-01-01

    1. The reality of a chemical cycle proposed to describe the rhodopsin system is tested with dark adaptation measurements. 2. The first few minutes of rod dark adaptation are rapid following short, slower following long irradiation. As dark adaptation proceeds, the slow process grows more prominent, and occupies completely the final stages of adaptation. 3. Light adaptation displays similar duality. As the exposure to light of constant intensity lengthens, the visual threshold rises, and independently the speed of dark adaptation decreases. 4. These results conform with predictions from the chemical equations. PMID:19873041

  20. Visualization of Scalar Adaptive Mesh Refinement Data

    SciTech Connect

    VACET; Weber, Gunther; Weber, Gunther H.; Beckner, Vince E.; Childs, Hank; Ligocki, Terry J.; Miller, Mark C.; Van Straalen, Brian; Bethel, E. Wes

    2007-12-06

    Adaptive Mesh Refinement (AMR) is a highly effective computation method for simulations that span a large range of spatiotemporal scales, such as astrophysical simulations, which must accommodate ranges from interstellar to sub-planetary. Most mainstream visualization tools still lack support for AMR grids as a first class data type and AMR code teams use custom built applications for AMR visualization. The Department of Energy's (DOE's) Science Discovery through Advanced Computing (SciDAC) Visualization and Analytics Center for Enabling Technologies (VACET) is currently working on extending VisIt, which is an open source visualization tool that accommodates AMR as a first-class data type. These efforts will bridge the gap between general-purpose visualization applications and highly specialized AMR visual analysis applications. Here, we give an overview of the state of the art in AMR scalar data visualization research.

  1. Visual adaptation provides objective electrophysiological evidence of facial identity discrimination.

    PubMed

    Retter, Talia L; Rossion, Bruno

    2016-07-01

    Discrimination of facial identities is a fundamental function of the human brain that is challenging to examine with macroscopic measurements of neural activity, such as those obtained with functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Although visual adaptation or repetition suppression (RS) stimulation paradigms have been successfully implemented to this end with such recording techniques, objective evidence of an identity-specific discrimination response due to adaptation at the level of the visual representation is lacking. Here, we addressed this issue with fast periodic visual stimulation (FPVS) and EEG recording combined with a symmetry/asymmetry adaptation paradigm. Adaptation to one facial identity is induced through repeated presentation of that identity at a rate of 6 images per second (6 Hz) over 10 sec. Subsequently, this identity is presented in alternation with another facial identity (i.e., its anti-face, both faces being equidistant from an average face), producing an identity repetition rate of 3 Hz over a 20 sec testing sequence. A clear EEG response at 3 Hz is observed over the right occipito-temporal (ROT) cortex, indexing discrimination between the two facial identities in the absence of an explicit behavioral discrimination measure. This face identity discrimination occurs immediately after adaptation and disappears rapidly within 20 sec. Importantly, this 3 Hz response is not observed in a control condition without the single-identity 10 sec adaptation period. These results indicate that visual adaptation to a given facial identity produces an objective (i.e., at a pre-defined stimulation frequency) electrophysiological index of visual discrimination between that identity and another, and provides a unique behavior-free quantification of the effect of visual adaptation.

  2. Perceptual learning reconfigures the effects of visual adaptation.

    PubMed

    McGovern, David P; Roach, Neil W; Webb, Ben S

    2012-09-26

    Our sensory experiences over a range of different timescales shape our perception of the environment. Two particularly striking short-term forms of plasticity with manifestly different time courses and perceptual consequences are those caused by visual adaptation and perceptual learning. Although conventionally treated as distinct forms of experience-dependent plasticity, their neural mechanisms and perceptual consequences have become increasingly blurred, raising the possibility that they might interact. To optimize our chances of finding a functionally meaningful interaction between learning and adaptation, we examined in humans the perceptual consequences of learning a fine discrimination task while adapting the neurons that carry most information for performing this task. Learning improved discriminative accuracy to a level that ultimately surpassed that in an unadapted state. This remarkable improvement came at a price: adapting directions that before learning had little effect elevated discrimination thresholds afterward. The improvements in discriminative accuracy grew quickly and surpassed unadapted levels within the first few training sessions, whereas the deterioration in discriminative accuracy had a different time course. This learned reconfiguration of adapted discriminative accuracy occurred without a concomitant change to the characteristic perceptual biases induced by adaptation, suggesting that the system was still in an adapted state. Our results point to a functionally meaningful push-pull interaction between learning and adaptation in which a gain in sensitivity in one adapted state is balanced by a loss of sensitivity in other adapted states.

  3. Content adaptation for visual impairment in MPEG-21

    NASA Astrophysics Data System (ADS)

    Yang, Seungji; Thang, Truong C.; Ro, Yong M.

    2004-06-01

    In this paper, we propose content adaptation for visual impairments in MPEG-21. The proposed content adaptation aims to give enhanced visual accessibility to users with visual impairment in MPEG-21. In this paper, we consider two major visual impairments: low vision impairment and color vision deficiency. The proposed method includes description for the visual impairments and content adaptation technique based on it. We have developed a symptom-based description of visual impairment characteristics for users with visual impairment in the context of MPEG-21 digital item adaptation (DIA). To verify usefulness of the proposed method, we performed some experiments with the content adaptation based on the description in MPEG-21. The experiment results showed that the proposed method is effective content adaptation for user with visual impairment and gives enhanced visual accessibility to them.

  4. Adaptive multiconfigurational wave functions

    SciTech Connect

    Evangelista, Francesco A.

    2014-03-28

    A method is suggested to build simple multiconfigurational wave functions specified uniquely by an energy cutoff Λ. These are constructed from a model space containing determinants with energy relative to that of the most stable determinant no greater than Λ. The resulting Λ-CI wave function is adaptive, being able to represent both single-reference and multireference electronic states. We also consider a more compact wave function parameterization (Λ+SD-CI), which is based on a small Λ-CI reference and adds a selection of all the singly and doubly excited determinants generated from it. We report two heuristic algorithms to build Λ-CI wave functions. The first is based on an approximate prescreening of the full configuration interaction space, while the second performs a breadth-first search coupled with pruning. The Λ-CI and Λ+SD-CI approaches are used to compute the dissociation curve of N{sub 2} and the potential energy curves for the first three singlet states of C{sub 2}. Special attention is paid to the issue of energy discontinuities caused by changes in the size of the Λ-CI wave function along the potential energy curve. This problem is shown to be solvable by smoothing the matrix elements of the Hamiltonian. Our last example, involving the Cu{sub 2}O{sub 2}{sup 2+} core, illustrates an alternative use of the Λ-CI method: as a tool to both estimate the multireference character of a wave function and to create a compact model space to be used in subsequent high-level multireference coupled cluster computations.

  5. Visualizing Search Behavior with Adaptive Discriminations

    PubMed Central

    Cook, Robert G.; Qadri, Muhammad A. J.

    2014-01-01

    We examined different aspects of the visual search behavior of a pigeon using an open-ended, adaptive testing procedure controlled by a genetic algorithm. The animal had to accurately search for and peck a gray target element randomly located from among a variable number of surrounding darker and lighter distractor elements. Display composition was controlled by a genetic algorithm involving the multivariate configuration of different parameters or genes (number of distractors, element size, shape, spacing, target brightness, and distractor brightness). Sessions were composed of random displays, testing randomized combinations of these genes, and selected displays, representing the varied descendants of displays correctly identified by the pigeon. Testing a larger number of random displays than done previously, it was found that the bird’s solution to the search task was highly stable and did not change with extensive experience in the task. The location and shape of this attractor was visualized using multivariate behavioral surfaces in which element size and the number of distractors were the most important factors controlling search accuracy and search time. The resulting visualizations of the bird’s search behavior are discussed with reference to the potential of using adaptive, open-ended experimental techniques for investigating animal cognition and their implications for Bond and Kamil’s innovative development of virtual ecologies using an analogous methodology. PMID:24370702

  6. Saccade adaptation specific to visual context.

    PubMed

    Herman, James P; Harwood, Mark R; Wallman, Josh

    2009-04-01

    When saccades consistently overshoot their targets, saccade amplitudes gradually decrease, thereby maintaining accuracy. This adaptive process has been seen as a form of motor learning that copes with changes in physical parameters of the eye and its muscles, brought about by aging or pathology. One would not expect such a motor-repair mechanism to be specific to the visual properties of the target stimulus. We had subjects make saccades to sudden movements of either of two targets-a steadily illuminated circle or a flickering circle-one of which stepped back during each saccade it elicited, simulating the effect of a hypermetric saccade. Saccade gain (saccade amplitude/target amplitude) decreased by 15% for the target that stepped back versus 6% for the target that did not step back. Most of the change in gain between successive blocks of trials of each type occurred on the first saccade of the block, decreasing by 0.12 on the first trial of a step-back block and increasing by 0.1 on the first trial of a no-step-back block. The differential adaptation of the two targets required postsaccadic feedback of both target types, as shown in a separate experiment, in which saccades to only one target received feedback, and the gain did not differ between the two target types. This demonstration that a context defined by a visual stimulus can serve as an effective cue for switching saccade gain between states suggests that saccade adaptation may have a heretofore unsuspected dimension of adaptability.

  7. UAV visual signature suppression via adaptive materials

    NASA Astrophysics Data System (ADS)

    Barrett, Ron; Melkert, Joris

    2005-05-01

    Visual signature suppression (VSS) methods for several classes of aircraft from WWII on are examined and historically summarized. This study shows that for some classes of uninhabited aerial vehicles (UAVs), primary mission threats do not stem from infrared or radar signatures, but from the amount that an aircraft visually stands out against the sky. The paper shows that such visual mismatch can often jeopardize mission success and/or induce the destruction of the entire aircraft. A psycho-physioptical study was conducted to establish the definition and benchmarks of a Visual Cross Section (VCS) for airborne objects. This study was centered on combining the effects of size, shape, color and luminosity or effective illumance (EI) of a given aircraft to arrive at a VCS. A series of tests were conducted with a 6.6ft (2m) UAV which was fitted with optically adaptive electroluminescent sheets at altitudes of up to 1000 ft (300m). It was shown that with proper tailoring of the color and luminosity, the VCS of the aircraft dropped from more than 4,200cm2 to less than 1.8cm2 at 100m (the observed lower limit of the 20-20 human eye in this study). In laypersons terms this indicated that the UAV essentially "disappeared". This study concludes with an assessment of the weight and volume impact of such a Visual Suppression System (VSS) on the UAV, showing that VCS levels on this class UAV can be suppressed to below 1.8cm2 for aircraft gross weight penalties of only 9.8%.

  8. Adaptive Pulvinar Circuitry Supports Visual Cognition.

    PubMed

    Bridge, Holly; Leopold, David A; Bourne, James A

    2016-02-01

    The pulvinar is the largest thalamic nucleus in primates and one of the most mysterious. Endeavors to understand its role in vision have focused on its abundant connections with the visual cortex. While its connectivity mapping in the cortex displays a broad topographic organization, its projections are also marked by considerable convergence and divergence. As a result, the pulvinar is often regarded as a central forebrain hub. Moreover, new evidence suggests that its comparatively modest input from structures such as the retina and superior colliculus may critically shape the functional organization of the visual cortex, particularly during early development. Here we review recent studies that cast fresh light on how the many convergent pathways through the pulvinar contribute to visual cognition.

  9. Cascaded Effects of Spatial Adaptation in the Early Visual System

    PubMed Central

    Dhruv, Neel T.; Carandini, Matteo

    2014-01-01

    Summary Virtually all stages of the visual system exhibit adaptation: neurons adjust their responses based on the recent stimulus history. While some of these adjustments occur at specific stages, others may be inherited from earlier stages. How do adaptation effects cascade along the visual system? We measured spatially selective adaptation at two successive stages in the mouse visual system: visual thalamus (LGN) and primary visual cortex (V1). This form of adaptation affected both stages but in drastically different ways: in LGN it only changed response gain, while in V1 it also shifted spatial tuning away from the adaptor. These effects, however, are reconciled by a simple model whereby V1 neurons summate LGN inputs with a fixed, unadaptable weighting profile. These results indicate that adaptation effects cascade through the visual system, that this cascading can shape selectivity, and that the rules of integration from one stage to the next are not themselves adaptable. PMID:24507190

  10. Cascaded effects of spatial adaptation in the early visual system.

    PubMed

    Dhruv, Neel T; Carandini, Matteo

    2014-02-05

    Virtually all stages of the visual system exhibit adaptation: neurons adjust their responses based on the recent stimulus history. While some of these adjustments occur at specific stages, others may be inherited from earlier stages. How do adaptation effects cascade along the visual system? We measured spatially selective adaptation at two successive stages in the mouse visual system: visual thalamus (LGN) and primary visual cortex (V1). This form of adaptation affected both stages but in drastically different ways: in LGN it only changed response gain, while in V1 it also shifted spatial tuning away from the adaptor. These effects, however, are reconciled by a simple model whereby V1 neurons summate LGN inputs with a fixed, unadaptable weighting profile. These results indicate that adaptation effects cascade through the visual system, that this cascading can shape selectivity, and that the rules of integration from one stage to the next are not themselves adaptable.

  11. Adaptive information interactive mechanism for multi-UAV visual navigation

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Dai, Qionghai

    2012-06-01

    Multi-unmanned aerial vehicle (UAV) cooperative communication for visual navigation has recently generated significant concern. It has large amounts of visual information to be transmitted and processed among UAVs with realtime requirements. And the UAV clusters have self-organized, time-varying and high dynamic characteristics. Considering the above conditions, we propose an adaptive information interactive mechanism (AIIM) for multi-UAV visual navigation. In the mechanism, the function modules for UAV inter-communication interface are designed, the mobility-based link lifetime is established and the information interactive protocol is presented. Thus we combine the mobility of UAVs with the corresponding communication requirements to make effective information interaction for UAVs. Task-oriented distributed control is adopted to improve the collaboration flexibility in the multi-UAV visual navigation system. In order to timely obtain the necessary visual information, each UAV can cooperate with other relevant UAVs which meet some certain terms such as situation, task or environmental conditions. Simulation results are presented to show the validity of the proposed mechanism in terms of end-to-end delay and links stability.

  12. Secondary tasks impair adaptation to step and gradual visual displacements

    PubMed Central

    Galea, J.M.; Sami, S.; Albert, N.B.; Miall, R.C.

    2016-01-01

    Performing two competing tasks can result in dividing cognitive resources between the tasks and impaired motor adaptation. In previous work we have reported impaired learning when participants had to switch from one visual displacement adaptation task to another. Here we examined whether or not a secondary task had a similar effect on adaptation to a visual displacement . The resource dividing task involved simultaneously adapting to a step visual displacement whilst vocally shadowing an auditory stimulus . The switching task required participants to adapt to opposing visual displacements in an alternating manner with the left and right hands. We found that both manipulations had a detrimental effect on adaptation rate. We then integrated these tasks and found the combination caused a greater decrease in adaptation rate than either manipulation in isolation. Experiment 2 showed that adaptation to a gradually imposed visual displacement was influenced in a similar manner to step adaptation. Therefore although gradual adaptation involves minimal awareness it still can be disrupted by a cognitively demanding secondary task. We propose that awareness and cognitive resource can be regarded as qualitatively different but that awareness may be a marker of the amount of resource required. For example, large errors are both noticed and require substantial cognitive resource to connect. However a lack of awareness does not mean an adaptation task will be resistant to interference from a resource consuming secondary task. PMID:20101396

  13. Adaptive Control of Visually Guided Grasping in Neural Networks

    DTIC Science & Technology

    1990-03-12

    U01ITU S.WM NONnumsen Adaptive Control of Visually Guided Grasping in Neural Networks AFOSR-89-&CO030 88-NL-209 L AUTHOrSF 2313/A8 00 61102F (V) Dr...FINAL REPORT ADAPTIVE CONTROL OF VISUALLY GUIDED GRASPING IN NEURAL NETWORKS Neurogen Laboratories Inc. Project Summary Research performed for AFOSR...arm’s length in position and 6 degrees in orientation. Keywords: Neural Networks , Adaptive Motor Control, Sensory-Motor sensation Introduction The human

  14. Adaptive Behavior of Children and Adolescents with Visual Impairments

    ERIC Educational Resources Information Center

    Papadopoulos, Konstantinos; Metsiou, Katerina; Agaliotis, Ioannis

    2011-01-01

    The present study explored the total adaptive behavior of children and adolescents with visual impairments, as well as their adaptive behavior in each of the domains of Communication, Daily Living Skills, and Socialization. Moreover, the predictors of the performance and developmental delay in adaptive behavior were investigated. Instrumentation…

  15. Stimulus relevance modulates contrast adaptation in visual cortex

    PubMed Central

    Keller, Andreas J; Houlton, Rachael; Kampa, Björn M; Lesica, Nicholas A; Mrsic-Flogel, Thomas D; Keller, Georg B; Helmchen, Fritjof

    2017-01-01

    A general principle of sensory processing is that neurons adapt to sustained stimuli by reducing their response over time. Most of our knowledge on adaptation in single cells is based on experiments in anesthetized animals. How responses adapt in awake animals, when stimuli may be behaviorally relevant or not, remains unclear. Here we show that contrast adaptation in mouse primary visual cortex depends on the behavioral relevance of the stimulus. Cells that adapted to contrast under anesthesia maintained or even increased their activity in awake naïve mice. When engaged in a visually guided task, contrast adaptation re-occurred for stimuli that were irrelevant for solving the task. However, contrast adaptation was reversed when stimuli acquired behavioral relevance. Regulation of cortical adaptation by task demand may allow dynamic control of sensory-evoked signal flow in the neocortex. DOI: http://dx.doi.org/10.7554/eLife.21589.001 PMID:28130922

  16. Security of visual hash function

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Regunathan; Xiong, Ziyou; Memon, Nasir D.

    2003-06-01

    Robust hash functions are central to the security of multimedia content authentication systems. Such functions are sensitive to a key but robust to many allowed signal processing operations on the underlying content. Robustness of the hash function to changes in the original content implies the existence of a cluster in the feature space around the original contents feature vector, any point within which getting hashed to the same output. The shape and size of the cluster determines the trade-off between the robustness offered and the security of the authentication system based on the robust hash function. The clustering itself is based on a secret key and hence unknown to the attacker. However, we show in this paper that the specific clustering arrived at by a robust hash function may be possible to learn. Specifically, we look at a well known robust hash function for image data called the Visual Hash Function (VHF). Given just an input and its hash value, we show how to construct a statistical model of the hash function, without any knowledge of the secret key used to compute the hash. We also show how to use this model to engineer arbitrary and malicious collisions. Finally, we propose one possible modification to VHF so that constructing a model that mimics its behavior becomes difficult.

  17. Enhanced visual adaptation in cochlear implant users revealed by concurrent EEG-fNIRS.

    PubMed

    Chen, Ling-Chia; Stropahl, Maren; Schönwiesner, Marc; Debener, Stefan

    2017-02-01

    Previous studies have observed lower visual cortex activation for visual processing in cochlear implant (CI) users compared to normal hearing controls, while others reported enhanced visual speechreading abilities in CI users. The present work investigated whether lower visual cortical activation for visual processing can be explained by a more efficient visual sensory encoding in CI users. Specifically, we investigated whether CI users show enhanced stimulus-specific adaptation for visual stimuli compared to controls. Auditory sensory adaptation was also investigated to explore the sensory specificity of the predicted effect. Twenty post-lingually deafened adult CI users and twenty age-matched controls were presented with repeated visual and auditory stimuli during simultaneous acquisition of electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS). By integrating EEG and fNIRS signals we found significantly enhanced visual adaptation and lower visual cortex activation in CI users compared to controls. That is, responses to repeated visual stimuli decreased more prominently in CI users than in controls. The results suggest that CI users process visual stimuli more efficiently than controls.

  18. The Adaptive Analysis of Visual Cognition using Genetic Algorithms

    PubMed Central

    Cook, Robert G.; Qadri, Muhammad A. J.

    2014-01-01

    Two experiments used a novel, open-ended, and adaptive test procedure to examine visual cognition in animals. Using a genetic algorithm, a pigeon was tested repeatedly from a variety of different initial conditions for its solution to an intermediate brightness search task. On each trial, the animal had to accurately locate and peck a target element of intermediate brightness from among a variable number of surrounding darker and lighter distractor elements. Displays were generated from six parametric variables, or genes (distractor number, element size, shape, spacing, target brightness, distractor brightness). Display composition changed over time, or evolved, as a function of the bird’s differential accuracy within the population of values for each gene. Testing three randomized initial conditions and one set of controlled initial conditions, element size and number of distractors were identified as the most important factors controlling search accuracy, with distractor brightness, element shape, and spacing making secondary contributions. The resulting changes in this multidimensional stimulus space suggested the existence of a set of conditions that the bird repeatedly converged upon regardless of initial conditions. This psychological “attractor” represents the cumulative action of the cognitive operations used by the pigeon in solving and performing this search task. The results are discussed regarding their implications for visual cognition in pigeons and the usefulness of adaptive, subject-driven experimentation for investigating human and animal cognition more generally. PMID:24000905

  19. Adapting the Brief COPE for Chinese Adolescents with Visual Impairments

    ERIC Educational Resources Information Center

    Yuan, Wei; Zhang, Li-fang; Li, Bing

    2017-01-01

    Introduction: The present research pioneered the effort in assessing adolescents' coping with visual impairment through adapting the Brief COPE in an eastern context. The first study preliminarily explored the applicability of the Brief COPE to Chinese adolescent students with visual impairments. Based on the results, the Brief COPE was modified…

  20. Visual Bias Predicts Gait Adaptability in Novel Sensory Discordant Conditions

    NASA Technical Reports Server (NTRS)

    Brady, Rachel A.; Batson, Crystal D.; Peters, Brian T.; Mulavara, Ajitkumar P.; Bloomberg, Jacob J.

    2010-01-01

    We designed a gait training study that presented combinations of visual flow and support-surface manipulations to investigate the response of healthy adults to novel discordant sensorimotor conditions. We aimed to determine whether a relationship existed between subjects visual dependence and their postural stability and cognitive performance in a new discordant environment presented at the conclusion of training (Transfer Test). Our training system comprised a treadmill placed on a motion base facing a virtual visual scene that provided a variety of sensory challenges. Ten healthy adults completed 3 training sessions during which they walked on a treadmill at 1.1 m/s while receiving discordant support-surface and visual manipulations. At the first visit, in an analysis of normalized torso translation measured in a scene-movement-only condition, 3 of 10 subjects were classified as visually dependent. During the Transfer Test, all participants received a 2-minute novel exposure. In a combined measure of stride frequency and reaction time, the non-visually dependent subjects showed improved adaptation on the Transfer Test compared to their visually dependent counterparts. This finding suggests that individual differences in the ability to adapt to new sensorimotor conditions may be explained by individuals innate sensory biases. An accurate preflight assessment of crewmembers biases for visual dependence could be used to predict their propensities to adapt to novel sensory conditions. It may also facilitate the development of customized training regimens that could expedite adaptation to alternate gravitational environments.

  1. Reorganization of early visual cortex functional connectivity following selective peripheral and central visual loss

    PubMed Central

    Sabbah, Norman; Sanda, Nicolae; Authié, Colas N.; Mohand-Saïd, Saddek; Sahel, José-Alain; Habas, Christophe; Amedi, Amir; Safran, Avinoam B.

    2017-01-01

    Behavioral alterations emerging after central or peripheral vision loss suggest that cerebral reorganization occurs for both the afferented and deafferented early visual cortex (EVC). We explored the functional reorganization of the central and peripheral EVC following visual field defects specifically affecting central or peripheral vision. Compared to normally sighted, afferented central and peripheral EVC enhance their functional connectivity with areas involved in visual processing, whereas deafferented central and peripheral EVC increase their functional connectivity with more remote regions. The connectivity pattern of afferented EVC suggests adaptive changes that might enhance the visual processing capacity whereas the connectivity pattern of deafferented EVC may reflect the involvement of these regions in high-order mechanisms. Characterizing and understanding the plastic changes induced by these visual defects is essential for any attempt to develop efficient rehabilitation strategies. PMID:28233790

  2. Reorganization of early visual cortex functional connectivity following selective peripheral and central visual loss.

    PubMed

    Sabbah, Norman; Sanda, Nicolae; Authié, Colas N; Mohand-Saïd, Saddek; Sahel, José-Alain; Habas, Christophe; Amedi, Amir; Safran, Avinoam B

    2017-02-24

    Behavioral alterations emerging after central or peripheral vision loss suggest that cerebral reorganization occurs for both the afferented and deafferented early visual cortex (EVC). We explored the functional reorganization of the central and peripheral EVC following visual field defects specifically affecting central or peripheral vision. Compared to normally sighted, afferented central and peripheral EVC enhance their functional connectivity with areas involved in visual processing, whereas deafferented central and peripheral EVC increase their functional connectivity with more remote regions. The connectivity pattern of afferented EVC suggests adaptive changes that might enhance the visual processing capacity whereas the connectivity pattern of deafferented EVC may reflect the involvement of these regions in high-order mechanisms. Characterizing and understanding the plastic changes induced by these visual defects is essential for any attempt to develop efficient rehabilitation strategies.

  3. The PCNN adaptive segmentation algorithm based on visual perception

    NASA Astrophysics Data System (ADS)

    Zhao, Yanming

    To solve network adaptive parameter determination problem of the pulse coupled neural network (PCNN), and improve the image segmentation results in image segmentation. The PCNN adaptive segmentation algorithm based on visual perception of information is proposed. Based on the image information of visual perception and Gabor mathematical model of Optic nerve cells receptive field, the algorithm determines adaptively the receptive field of each pixel of the image. And determines adaptively the network parameters W, M, and β of PCNN by the Gabor mathematical model, which can overcome the problem of traditional PCNN parameter determination in the field of image segmentation. Experimental results show that the proposed algorithm can improve the region connectivity and edge regularity of segmentation image. And also show the PCNN of visual perception information for segmentation image of advantage.

  4. Hour-long adaptation in the awake early visual system.

    PubMed

    Stoelzel, Carl R; Huff, Joseph M; Bereshpolova, Yulia; Zhuang, Jun; Hei, Xiaojuan; Alonso, Jose-Manuel; Swadlow, Harvey A

    2015-08-01

    Sensory adaptation serves to adjust awake brains to changing environments on different time scales. However, adaptation has been studied traditionally under anesthesia and for short time periods. Here, we demonstrate in awake rabbits a novel type of sensory adaptation that persists for >1 h and acts on visual thalamocortical neurons and their synapses in the input layers of the visual cortex. Following prolonged visual stimulation (10-30 min), cells in the dorsal lateral geniculate nucleus (LGN) show a severe and prolonged reduction in spontaneous firing rate. This effect is bidirectional, and prolonged visually induced response suppression is followed by a prolonged increase in spontaneous activity. The reduction in thalamic spontaneous activity following prolonged visual activation is accompanied by increases in 1) response reliability, 2) signal detectability, and 3) the ratio of visual signal/spontaneous activity. In addition, following such prolonged activation of an LGN neuron, the monosynaptic currents generated by thalamic impulses in layer 4 of the primary visual cortex are enhanced. These results demonstrate that in awake brains, prolonged sensory stimulation can have a profound, long-lasting effect on the information conveyed by thalamocortical inputs to the visual cortex.

  5. Adaptive, multiresolution visualization of large data sets using parallel octrees.

    SciTech Connect

    Freitag, L. A.; Loy, R. M.

    1999-06-10

    The interactive visualization and exploration of large scientific data sets is a challenging and difficult task; their size often far exceeds the performance and memory capacity of even the most powerful graphics work-stations. To address this problem, we have created a technique that combines hierarchical data reduction methods with parallel computing to allow interactive exploration of large data sets while retaining full-resolution capability. The hierarchical representation is built in parallel by strategically inserting field data into an octree data structure. We provide functionality that allows the user to interactively adapt the resolution of the reduced data sets so that resolution is increased in regions of interest without sacrificing local graphics performance. We describe the creation of the reduced data sets using a parallel octree, the software architecture of the system, and the performance of this system on the data from a Rayleigh-Taylor instability simulation.

  6. Adaptive Acceleration of Visually Evoked Smooth Eye Movements in Mice

    PubMed Central

    2016-01-01

    The optokinetic response (OKR) consists of smooth eye movements following global motion of the visual surround, which suppress image slip on the retina for visual acuity. The effective performance of the OKR is limited to rather slow and low-frequency visual stimuli, although it can be adaptably improved by cerebellum-dependent mechanisms. To better understand circuit mechanisms constraining OKR performance, we monitored how distinct kinematic features of the OKR change over the course of OKR adaptation, and found that eye acceleration at stimulus onset primarily limited OKR performance but could be dramatically potentiated by visual experience. Eye acceleration in the temporal-to-nasal direction depended more on the ipsilateral floccular complex of the cerebellum than did that in the nasal-to-temporal direction. Gaze-holding following the OKR was also modified in parallel with eye-acceleration potentiation. Optogenetic manipulation revealed that synchronous excitation and inhibition of floccular complex Purkinje cells could effectively accelerate eye movements in the nasotemporal and temporonasal directions, respectively. These results collectively delineate multiple motor pathways subserving distinct aspects of the OKR in mice and constrain hypotheses regarding cellular mechanisms of the cerebellum-dependent tuning of movement acceleration. SIGNIFICANCE STATEMENT Although visually evoked smooth eye movements, known as the optokinetic response (OKR), have been studied in various species for decades, circuit mechanisms of oculomotor control and adaptation remain elusive. In the present study, we assessed kinematics of the mouse OKR through the course of adaptation training. Our analyses revealed that eye acceleration at visual-stimulus onset primarily limited working velocity and frequency range of the OKR, yet could be dramatically potentiated during OKR adaptation. Potentiation of eye acceleration exhibited different properties between the nasotemporal and

  7. Visual Function in Geriatric Eye Disease

    ERIC Educational Resources Information Center

    Faye, Eleanor E.

    1971-01-01

    Visual functioning, treatment, and helpful low vision aids are discussed in relation to four major eye diseases of the elderly: cataract, macular degeneration, glaucoma, and diabetic retinopathy. (KW)

  8. Production-quality Tools for Adaptive Mesh RefinementVisualization

    SciTech Connect

    Weber, Gunther H.; Childs, Hank; Bonnell, Kathleen; Meredith,Jeremy; Miller, Mark; Whitlock, Brad; Bethel, E. Wes

    2007-10-25

    Adaptive Mesh Refinement (AMR) is a highly effectivesimulation method for spanning a large range of spatiotemporal scales,such as astrophysical simulations that must accommodate ranges frominterstellar to sub-planetary. Most mainstream visualization tools stilllack support for AMR as a first class data type and AMR code teams usecustom built applications for AMR visualization. The Department ofEnergy's (DOE's) Science Discovery through Advanced Computing (SciDAC)Visualization and Analytics Center for Enabling Technologies (VACET) isextending and deploying VisIt, an open source visualization tool thataccommodates AMR as a first-class data type, for use asproduction-quality, parallel-capable AMR visual data analysisinfrastructure. This effort will help science teams that use AMR-basedsimulations and who develop their own AMR visual data analysis softwareto realize cost and labor savings.

  9. Design of a Fat-Based Adaptive Visual Servoing for Robots with Time Varying Uncertainties

    NASA Astrophysics Data System (ADS)

    Chien, Ming-Chih; Huang, An-Chyau

    2010-05-01

    Most present adaptive control strategies for visual servoing of robots have assumed that the unknown camera parameters, kinematics, and dynamics of visual servoing system should be linearly parameterized in the regressor matrix form. This is because the limitation of the traditional adaptive design in which the uncertainties should be time-invariant such that all time varying terms in the visual servoing system are collected inside the regressor matrix. However, derivation of the regressor matrix is tedious. In this article, a FAT (function approximation technique) based adaptive controller is designed for visual servo robots without the need for the regressor matrix. A Lyapunov-like analysis is used to justify the closed-loop stability and boundedness of internal signals. Moreover, the upper bounds of tracking errors in the transient state are also derived. Computer simulation results are presented to demonstrate the usefulness of the proposed scheme.

  10. Visual adaptation to thin and fat bodies transfers across identity.

    PubMed

    Hummel, Dennis; Rudolf, Anne K; Untch, Karl-Heinz; Grabhorn, Ralph; Mohr, Harald M

    2012-01-01

    Visual perception is highly variable and can be influenced by the surrounding world. Previous research has revealed that body perception can be biased due to adaptation to thin or fat body shapes. The aim of the present study was to show that adaptation to certain body shapes and the resulting perceptual biases transfer across different identities of adaptation and test stimuli. We designed two similar adaptation experiments in which healthy female participants adapted to pictures of either thin or fat bodies and subsequently compared more or less distorted pictures of their own body to their actual body shape. In the first experiment (n = 16) the same identity was used as adaptation and test stimuli (i.e. pictures of the participant's own body) while in the second experiment (n = 16) we used pictures of unfamiliar thin or fat bodies as adaptation stimuli. We found comparable adaptation effects in both experiments: After adaptation to a thin body, participants rated a thinner than actual body picture to be the most realistic and vice versa. We therefore assume that adaptation to certain body shapes transfers across different identities. These results raise the questions of whether some type of natural adaptation occurs in everyday life. Natural and predominant exposure to certain bodily features like body shape--especially the thin ideal in Western societies--could bias perception for these features. In this regard, further research might shed light on aspects of body dissatisfaction and the development of body image disturbances in terms of eating disorders.

  11. Awareness of sensorimotor adaptation to visual rotations of different size.

    PubMed

    Werner, Susen; van Aken, Bernice C; Hulst, Thomas; Frens, Maarten A; van der Geest, Jos N; Strüder, Heiko K; Donchin, Opher

    2015-01-01

    Previous studies on sensorimotor adaptation revealed no awareness of the nature of the perturbation after adaptation to an abrupt 30° rotation of visual feedback or after adaptation to gradually introduced perturbations. Whether the degree of awareness depends on the magnitude of the perturbation, though, has as yet not been tested. Instead of using questionnaires, as was often done in previous work, the present study used a process dissociation procedure to measure awareness and unawareness. A naïve, implicit group and a group of subjects using explicit strategies adapted to 20°, 40° and 60° cursor rotations in different adaptation blocks that were each followed by determination of awareness and unawareness indices. The awareness index differed between groups and increased from 20° to 60° adaptation. In contrast, there was no group difference for the unawareness index, but it also depended on the size of the rotation. Early adaptation varied between groups and correlated with awareness: The more awareness a participant had developed the more the person adapted in the beginning of the adaptation block. In addition, there was a significant group difference for savings but it did not correlate with awareness. Our findings suggest that awareness depends on perturbation size and that aware and strategic processes are differentially involved during adaptation and savings. Moreover, the use of the process dissociation procedure opens the opportunity to determine awareness and unawareness indices in future sensorimotor adaptation research.

  12. AVATAR -- Adaptive Visualization Aid for Touring And Recovery

    SciTech Connect

    L. O. Hall; K. W. Bowyer; N. Chawla; T. Moore, Jr.; W. P. Kegelmeyer

    2000-01-01

    This document provides a report on the initial development of software which uses a standard visualization tool to determine, label and display salient regions in large 3D physics simulation datasets. This software uses parallel pattern recognition behind the scenes to handle the huge volume of data. This software is called AVATAR (Adaptive Visualization Aid for Touring and Recovery). It integrates approaches to gathering labeled training data, learning from large training sets utilizing parallelism and the final display of salient data in unseen visualization data sets. The paper uses vorticity fields for a large-eddy simulation to illustrate the method.

  13. Inferential functioning in visually impaired children.

    PubMed

    Puche-Navarro, Rebeca; Millán, Rafael

    2007-01-01

    The current study explores the inferential abilities of visually impaired children in a task presented in two formats, manipulative and verbal. The results showed that in the group of visually impaired children, just as with children with normal sight, there was a wide range of inference types. It was found that the visually impaired children perform slightly better in the use of inductive and relational inferences in the verbal format, while in the manipulative format children with normal sight perform better. These results suggest that in inferential functioning of young children, and especially visually impaired children, the format of the task influences performance more than the child's visual ability.

  14. Adaptive memory: thinking about function.

    PubMed

    Bell, Raoul; Röer, Jan P; Buchner, Axel

    2015-07-01

    Rating the relevance of words for the imagined situation of being stranded in the grasslands without survival material leads to exceptionally good memory for these words. This survival processing effect has received much attention because it promises to elucidate the evolutionary foundations of memory. However, the proximate mechanisms of the survival processing effect have to be identified before informed speculations about its adaptive function are possible. Here, we test and contrast 2 promising accounts of the survival processing effect. According to the 1st account, the effect is the consequence of the prioritized processing of threat-related information. According to the 2nd account, thinking about the relevance of items for survival stimulates thinking about object function, which is a particularly elaborate form of encoding. Experiment 1 showed that the emotional properties of the survival scenario, as manipulated by the negative or positive framing of the scenario, did not influence recall. A focus on threat at encoding led to worse recall than a focus on function. The latter finding was replicated in Experiment 2, which further showed that focusing on threat did not lead to a memory advantage over a pleasantness control condition. The beneficial effect of inducing a functional focus at encoding even surpasses that of the standard survival processing instruction. Together, the results support the theory that thinking about function is an important component of the survival processing effect.

  15. Visual Adaptation to Convexity in Macaque Area V4

    PubMed Central

    Müller, Kai-Markus; Wilke, Melanie; Leopold, David A.

    2009-01-01

    After-effects are perceptual illusions caused by visual adaptation to one or more stimulus attribute, such as orientation, motion, or shape, and are generally characterized by a repulsive shift in the perception of the adapted features in a corresponding test stimulus. Neurophysiological studies seeking to understand the basis of adaptation have observed firing rate reduction and changes in tuning of sensory neurons during periods of prolonged stimulation. In the domain of shape, recent psychophysical work has shown that adaptation to a convex pattern induces a subsequently seen rectangle to appear slightly concave. In the present study, we investigate the possible contribution of V4 neurons, which are thought to be involved in the coding of convexity, to such shape-specific adaptation. Visually responsive neurons were monitored during the brief presentation of simple shapes varying in their convexity level. Each test presentation was preceded by either a blank period or several seconds of adaptation to a convex or concave stimulus, presented in two different sizes. Adaptation consistently changed the tuning of neurons away from the convex or concave adaptor, shifting the response to the neutral rectangle in the direction of the opposite convexity. This repulsive shift was consistent with the known perceptual distortion associated with adaptation to such stimuli. Adaptation also caused a nonspecific decrease in firing, as well as the shape-selective suppression for the repeated presentation of the adaptor stimulus. The latter effects were observed whether or not the adapting and test stimuli matched closely in their size. Taken together, these results provide evidence for shape-specific adaptation of neurons in area V4, which may contribute to the perception of the convexity aftereffect. PMID:19345725

  16. Guided Text Search Using Adaptive Visual Analytics

    SciTech Connect

    Steed, Chad A; Symons, Christopher T; Senter, James K; DeNap, Frank A

    2012-10-01

    This research demonstrates the promise of augmenting interactive visualizations with semi- supervised machine learning techniques to improve the discovery of significant associations and insights in the search and analysis of textual information. More specifically, we have developed a system called Gryffin that hosts a unique collection of techniques that facilitate individualized investigative search pertaining to an ever-changing set of analytical questions over an indexed collection of open-source documents related to critical national infrastructure. The Gryffin client hosts dynamic displays of the search results via focus+context record listings, temporal timelines, term-frequency views, and multiple coordinate views. Furthermore, as the analyst interacts with the display, the interactions are recorded and used to label the search records. These labeled records are then used to drive semi-supervised machine learning algorithms that re-rank the unlabeled search records such that potentially relevant records are moved to the top of the record listing. Gryffin is described in the context of the daily tasks encountered at the US Department of Homeland Security s Fusion Center, with whom we are collaborating in its development. The resulting system is capable of addressing the analysts information overload that can be directly attributed to the deluge of information that must be addressed in the search and investigative analysis of textual information.

  17. VisAdapt: A Visualization Tool to Support Climate Change Adaptation.

    PubMed

    Johansson, Jimmy; Opach, Tomasz; Glaas, Erik; Neset, Tina-Simone; Navarra, Carlo; Linner, Bjorn-Ola; Rod, Jan Ketil

    2017-01-01

    The web-based visualization VisAdapt tool was developed to help laypeople in the Nordic countries assess how anticipated climate change will impact their homes. The tool guides users through a three-step visual process that helps them explore risks and identify adaptive actions specifically modified to their location and house type. This article walks through the tool's multistep, user-centered design process. Although VisAdapt's target end users are Nordic homeowners, the insights gained from the development process and the lessons learned from the project are applicable to a wide range of domains.

  18. Enhancing Functional Performance using Sensorimotor Adaptability Training Programs

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Mulavara, A. P.; Peters, B. T.; Brady, R.; Audas, C.; Ruttley, T. M.; Cohen, H. S.

    2009-01-01

    During the acute phase of adaptation to novel gravitational environments, sensorimotor disturbances have the potential to disrupt the ability of astronauts to perform functional tasks. The goal of this project is to develop a sensorimotor adaptability (SA) training program designed to facilitate recovery of functional capabilities when astronauts transition to different gravitational environments. The project conducted a series of studies that investigated the efficacy of treadmill training combined with a variety of sensory challenges designed to increase adaptability including alterations in visual flow, body loading, and support surface stability.

  19. Visuomotor adaptation to a visual rotation is gravity dependent.

    PubMed

    Toma, Simone; Sciutti, Alessandra; Papaxanthis, Charalambos; Pozzo, Thierry

    2015-03-15

    Humans perform vertical and horizontal arm motions with different temporal patterns. The specific velocity profiles are chosen by the central nervous system by integrating the gravitational force field to minimize energy expenditure. However, what happens when a visuomotor rotation is applied, so that a motion performed in the horizontal plane is perceived as vertical? We investigated the dynamic of the adaptation of the spatial and temporal properties of a pointing motion during prolonged exposure to a 90° visuomotor rotation, where a horizontal movement was associated with a vertical visual feedback. We found that participants immediately adapted the spatial parameters of motion to the conflicting visual scene in order to keep their arm trajectory straight. In contrast, the initial symmetric velocity profiles specific for a horizontal motion were progressively modified during the conflict exposure, becoming more asymmetric and similar to those appropriate for a vertical motion. Importantly, this visual effect that increased with repetitions was not followed by a consistent aftereffect when the conflicting visual feedback was absent (catch and washout trials). In a control experiment we demonstrated that an intrinsic representation of the temporal structure of perceived vertical motions could provide the error signal allowing for this progressive adaptation of motion timing. These findings suggest that gravity strongly constrains motor learning and the reweighting process between visual and proprioceptive sensory inputs, leading to the selection of a motor plan that is suboptimal in terms of energy expenditure.

  20. [Determination of visual function in legal assessment].

    PubMed

    Springer, C; Bültmann, S; Krastel, H; Rohrschneider, K

    2007-06-01

    For the determination of visual function an objective assessment is essential. Basic ophthalmologic examinations such as measurement of visual acuity and perimetry are dependent on patient statements. If the patient is not being able to provide adequate answers, as is the case for small children or mentally retarded patients, or also if the accuracy of the patient's statements is doubtful or simulation or aggravation is suspected, the denoted function in the evaluation of visual acuity has to be checked on consistency using different examination methods, and the results of objective functional tests, such as electrophysiology and morphological features, have to be taken into account.

  1. Visual functioning restoration developments in ARMD

    NASA Astrophysics Data System (ADS)

    Mumford, R. B.

    2006-09-01

    Recent progress in several fields has radically changed the expectations of low vision individuals. These changes augment existing prescription eye-care and electronic reading machines to improve recovery of visual function. Companies are reporting incidences of multi-line gains in visual acuity as their products for macular degeneration move through FDA approval stages. Funding for this research is rapidly increasing.

  2. Visual-field function in pseudophakia.

    PubMed

    Klewin, K M; Radius, R L; Schultz, R O

    1988-08-01

    An automated perimeter (Octopus 2000) was used to examine visual-field function in 52 pseudophakic eyes. Threshold sensitivity was reduced throughout the visual field by from 0.4 to 20.0 decibels from that of threshold sensitivity in age-matched normal eyes. This reduction was comparable to that seen in contact-lens-corrected aphakic eyes.

  3. Interocular transfer of adaptation in the primary visual cortex.

    PubMed

    Howarth, Christopher M; Vorobyov, Vasily; Sengpiel, Frank

    2009-08-01

    Prolonged viewing of an unchanging pattern causes adaptation, which can be demonstrated by visual aftereffects such as the tilt and waterfall illusions. In normal observers, these typically exhibit interocular transfer (IOT), being observed when the adapting and test stimuli are shown to different eyes. Convergence of inputs from both eyes upon binocular neurons only occurs in the primary visual cortex (V1), and adaptation is substantially a cortical phenomenon. However, little is known about a physiological substrate of IOT in V1 and how it relates to the binocularity of neurons and local ocular dominance (OD) column architecture. We employed optical imaging to obtain OD maps in cat V1 and recorded from single neurons at targeted penetration sites to quantify their adaptation by drifting gratings when adapter and test stimulus were presented either to the same or to the opposite eyes. In contrast to earlier reports, clear IOT of adaptation was observed for binocular as well as monocular neurons; at population level, its strength amounted to 55%. Moreover, the position of the cells with respect to OD column borders had no significant effect on the strength of IOT. IOT does not appear to strongly depend on conventional binocularity of neurons.

  4. Visual Function and Visual Acuity in an Urban Adult Population.

    ERIC Educational Resources Information Center

    Katz, J.; Tielsch, J. M.

    1996-01-01

    A survey of 6,850 adults age 40 or over concerning the effects of poor vision found that difficulties with reading or other near-vision activities were the most common complaint. One-fourth reported limitations in activities because of poor vision. Factors associated with loss of visual function were general health status, educational level, and…

  5. Visuomanual coordination in childhood: adaptation to visual distortion.

    PubMed

    Ferrel-Chapus, Carole; Hay, Laurette; Olivier, Isabelle; Bard, Chantal; Fleury, Michelle

    2002-06-01

    The aim of the experiment was to study the adaptive capacities of children to perform drawing movements while being visually perturbed. Children aged 5-11 years and a group of adults drew diamonds via information provided through a computer screen. The screen display was either upright or rotated 180 degrees. Results showed that the absence of direct vision of the hand yielded more perturbation in the youngest group of children compared to all other groups. In spite of some initial difficulty, all children reached accurate control after five trials. When faced with spatial rotations of the visual field, youngsters were again more perturbed than others. All children showed the same rate of adaptation to visual rotations, but they differed on adaptive strategies. Five- and 7-year-olds shifted to a feedforward mode of control consisting of the production of a rapid gesture, followed by error evaluation in order to correct their next movement. Older children were characterised by a progressive integration of reafferent visual and proprioceptive information. It resulted in an increase in duration of strokes and reduced speed, meaning enhanced on-line retrieval of information. However, 9-year-old children experienced more difficulty recuperating sensory information during movement than 11-year-olds, and kept using error feedback. Finally, visuomanual coordination in children aged 11 years, while slightly differing from that of adults, was not yet totally mature.

  6. Visual function and perinatal focal cerebral infarction.

    PubMed Central

    Mercuri, E; Atkinson, J; Braddick, O; Anker, S; Nokes, L; Cowan, F; Rutherford, M; Pennock, J; Dubowitz, L

    1996-01-01

    AIMS: To evaluate the visual function of infants with perinatal cerebral infarction in whom the site and size of the lesion has been determined using magnetic resonance imaging (MRI). METHODS: Twelve infants with cerebral infarction on MRI were studied with a battery of tests specifically designed to evaluate visual function in infancy. This included tests: for visual attention (fixation shifts); of cerebral asymmetry (optokinetic nystagmus, visual fields); for assessment of acuity (forced choice preferential looking); and neurophysiological measures of vision (phase reversal and orientation reversal visual evoked potential). RESULTS: A considerable incidence of abnormalities on at least one of the tests for visual function used was observed. The presence or severity of visual abnormalities could not always be predicted by the site and extent of the lesion seen on imaging. CONCLUSIONS: Early focal lesions affecting the visual pathway can, to some extent, be compensated for by the immature developing brain. These data suggest that all the infants presenting with focal lesions need to be investigated with a detailed assessment of various aspects of vision. Images PMID:8949687

  7. Adaptation to sensory input tunes visual cortex to criticality

    NASA Astrophysics Data System (ADS)

    Shew, Woodrow L.; Clawson, Wesley P.; Pobst, Jeff; Karimipanah, Yahya; Wright, Nathaniel C.; Wessel, Ralf

    2015-08-01

    A long-standing hypothesis at the interface of physics and neuroscience is that neural networks self-organize to the critical point of a phase transition, thereby optimizing aspects of sensory information processing. This idea is partially supported by strong evidence for critical dynamics observed in the cerebral cortex, but the impact of sensory input on these dynamics is largely unknown. Thus, the foundations of this hypothesis--the self-organization process and how it manifests during strong sensory input--remain unstudied experimentally. Here we show in visual cortex and in a computational model that strong sensory input initially elicits cortical network dynamics that are not critical, but adaptive changes in the network rapidly tune the system to criticality. This conclusion is based on observations of multifaceted scaling laws predicted to occur at criticality. Our findings establish sensory adaptation as a self-organizing mechanism that maintains criticality in visual cortex during sensory information processing.

  8. Optic Flow Dominates Visual Scene Polarity in Causing Adaptive Modification of Locomotor Trajectory

    NASA Technical Reports Server (NTRS)

    Nomura, Y.; Mulavara, A. P.; Richards, J. T.; Brady, R.; Bloomberg, Jacob J.

    2005-01-01

    Locomotion and posture are influenced and controlled by vestibular, visual and somatosensory information. Optic flow and scene polarity are two characteristics of a visual scene that have been identified as being critical in how they affect perceived body orientation and self-motion. The goal of this study was to determine the role of optic flow and visual scene polarity on adaptive modification in locomotor trajectory. Two computer-generated virtual reality scenes were shown to subjects during 20 minutes of treadmill walking. One scene was a highly polarized scene while the other was composed of objects displayed in a non-polarized fashion. Both virtual scenes depicted constant rate self-motion equivalent to walking counterclockwise around the perimeter of a room. Subjects performed Stepping Tests blindfolded before and after scene exposure to assess adaptive changes in locomotor trajectory. Subjects showed a significant difference in heading direction, between pre and post adaptation stepping tests, when exposed to either scene during treadmill walking. However, there was no significant difference in the subjects heading direction between the two visual scene polarity conditions. Therefore, it was inferred from these data that optic flow has a greater role than visual polarity in influencing adaptive locomotor function.

  9. Adaptive two-scale edge detection for visual pattern processing

    NASA Astrophysics Data System (ADS)

    Rahman, Zia-Ur; Jobson, Daniel J.; Woodell, Glenn A.

    2009-09-01

    Adaptive methods are defined and experimentally studied for a two-scale edge detection process that mimics human visual perception of edges and is inspired by the parvocellular (P) and magnocellular (M) physiological subsystems of natural vision. This two-channel processing consists of a high spatial acuity/coarse contrast channel (P) and a coarse acuity/fine contrast (M) channel. We perform edge detection after a very strong nonlinear image enhancement that uses smart Retinex image processing. Two conditions that arise from this enhancement demand adaptiveness in edge detection. These conditions are the presence of random noise further exacerbated by the enhancement process and the equally random occurrence of dense textural visual information. We examine how to best deal with both phenomena with an automatic adaptive computation that treats both high noise and dense textures as too much information and gracefully shifts from small-scale to medium-scale edge pattern priorities. This shift is accomplished by using different edge-enhancement schemes that correspond with the P- and M-channels of the human visual system. We also examine the case of adapting to a third image condition-namely, too little visual information-and automatically adjust edge-detection sensitivities when sparse feature information is encountered. When this methodology is applied to a sequence of images of the same scene but with varying exposures and lighting conditions, this edge-detection process produces pattern constancy that is very useful for several imaging applications that rely on image classification in variable imaging conditions.

  10. Atypical visual and somatosensory adaptation in schizophrenia-spectrum disorders

    PubMed Central

    Andrade, G N; Butler, J S; Peters, G A; Molholm, S; Foxe, J J

    2016-01-01

    Neurophysiological investigations in patients with schizophrenia consistently show early sensory processing deficits in the visual system. Importantly, comparable sensory deficits have also been established in healthy first-degree biological relatives of patients with schizophrenia and in first-episode drug-naive patients. The clear implication is that these measures are endophenotypic, related to the underlying genetic liability for schizophrenia. However, there is significant overlap between patient response distributions and those of healthy individuals without affected first-degree relatives. Here we sought to develop more sensitive measures of sensory dysfunction in this population, with an eye to establishing endophenotypic markers with better predictive capabilities. We used a sensory adaptation paradigm in which electrophysiological responses to basic visual and somatosensory stimuli presented at different rates (ranging from 250 to 2550 ms interstimulus intervals, in blocked presentations) were compared. Our main hypothesis was that adaptation would be substantially diminished in schizophrenia, and that this would be especially prevalent in the visual system. High-density event-related potential recordings showed amplitude reductions in sensory adaptation in patients with schizophrenia (N=15 Experiment 1, N=12 Experiment 2) compared with age-matched healthy controls (N=15 Experiment 1, N=12 Experiment 2), and this was seen for both sensory modalities. At the individual participant level, reduced adaptation was more robust for visual compared with somatosensory stimulation. These results point to significant impairments in short-term sensory plasticity across sensory modalities in schizophrenia. These simple-to-execute measures may prove valuable as candidate endophenotypes and will bear follow-up in future work. PMID:27163205

  11. Visual-adaptation-mechanism based underwater object extraction

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Wang, Huibin; Xu, Lizhong; Shen, Jie

    2014-03-01

    Due to the major obstacles originating from the strong light absorption and scattering in a dynamic underwater environment, underwater optical information acquisition and processing suffer from effects such as limited range, non-uniform lighting, low contrast, and diminished colors, causing it to become the bottleneck for marine scientific research and projects. After studying and generalizing the underwater biological visual mechanism, we explore its advantages in light adaption which helps animals to precisely sense the underwater scene and recognize their prey or enemies. Then, aiming to transform the significant advantage of the visual adaptation mechanism into underwater computer vision tasks, a novel knowledge-based information weighting fusion model is established for underwater object extraction. With this bionic model, the dynamical adaptability is given to the underwater object extraction task, making them more robust to the variability of the optical properties in different environments. The capability of the proposed method to adapt to the underwater optical environments is shown, and its outperformance for the object extraction is demonstrated by comparison experiments.

  12. Testing visual function in the clinical setting.

    PubMed

    Westheimer, Gerald

    2010-07-01

    The explosive growth of automatic examination of the eye, in particular for determining refractive corrections, invites an analysis of the strengths and limitations of these devices and their role in clinical decisions. Subjective refraction procedures are based on a patient's visual responses and these embrace many levels of additional optical and neural processing and factors involving the higher-order nervous system and perception. Because the ultimate mission is the maintenance and improvement of a patient's visual experiences, the optometric examination necessarily extends beyond the employment of automatic devices and therefore, should include engaging the patients in tests of their visual functions.

  13. Monitoring of visual function during parasellar surgery.

    PubMed

    Wilson, W B; Kirsch, W M; Neville, H; Stears, J; Feinsod, M; Lehman, R A

    1976-06-01

    Damage to the visual system is an unfortunate complication of surgery in the area of the optic chiasm. It is now possible tomonitor the functional status of the visual system intreoperatively at regulat intervals. This is accomplished by recording the Visual Evoked Response to flashes of light from light-emitting-eiodes. These diodes are embedded in a special plastic shell which inserts under the eye lids of each eye. Since the light comes from the diodes in the plastic shell, there is no need to disturb the surgical procedure when a test run is desired. A record is obtained by averaging 100 three-per-second flashes.

  14. Imaging visual function of the human brain

    SciTech Connect

    Marg, E.

    1988-10-01

    Imaging of human brain structure and activity with particular reference to visual function is reviewed along with methods of obtaining the data including computed tomographic (CT) scan, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and positron emission tomography (PET). The literature is reviewed and the potential for a new understanding of brain visual function is discussed. PET is reviewed from basic physical principles to the most recent visual brain findings with oxygen-15. It is shown that there is a potential for submillimeter localization of visual functions with sequentially different visual stimuli designed for the temporal separation of the responses. Single photon emission computed tomography (SPECT), a less expensive substitute for PET, is also discussed. MRS is covered from basic physical principles to the current state of the art of in vivo biochemical analysis. Future possible clinical applications are discussed. Improved understanding of the functional neural organization of vision and brain will open a window to maps and circuits of human brain function.119 references.

  15. Visual Servoing via Navigation Functions

    DTIC Science & Technology

    2002-02-06

    notation, we write ϕ ◦ ψ(q) = ϕ(q), and hence, in local coordinates ∇ϕ(q) = M−1(q) DTq ϕ(q) where (Dqϕ)i = ∂ϕ ∂qi , and M is the local representation of...the Riemannian metric. Gradient descent can now be achieved in local coordinates via q̇ = −M−1(q) DTq ϕ(q) (12) A smooth scalar valued function whose

  16. Recent Visual Experience Shapes Visual Processing in Rats through Stimulus-Specific Adaptation and Response Enhancement.

    PubMed

    Vinken, Kasper; Vogels, Rufin; Op de Beeck, Hans

    2017-03-20

    From an ecological point of view, it is generally suggested that the main goal of vision in rats and mice is navigation and (aerial) predator evasion [1-3]. The latter requires fast and accurate detection of a change in the visual environment. An outstanding question is whether there are mechanisms in the rodent visual system that would support and facilitate visual change detection. An experimental protocol frequently used to investigate change detection in humans is the oddball paradigm, in which a rare, unexpected stimulus is presented in a train of stimulus repetitions [4]. A popular "predictive coding" theory of cortical responses states that neural responses should decrease for expected sensory input and increase for unexpected input [5, 6]. Despite evidence for response suppression and enhancement in noninvasive scalp recordings in humans with this paradigm [7, 8], it has proven challenging to observe both phenomena in invasive action potential recordings in other animals [9-11]. During a visual oddball experiment, we recorded multi-unit spiking activity in rat primary visual cortex (V1) and latero-intermediate area (LI), which is a higher area of the rodent ventral visual stream. In rat V1, there was only evidence for response suppression related to stimulus-specific adaptation, and not for response enhancement. However, higher up in area LI, spiking activity showed clear surprise-based response enhancement in addition to stimulus-specific adaptation. These results show that neural responses along the rat ventral visual stream become increasingly sensitive to changes in the visual environment, suggesting a system specialized in the detection of unexpected events.

  17. Testing Visual Functions in Patients with Visual Prostheses

    NASA Astrophysics Data System (ADS)

    Wilke, Robert; Bach, Michael; Wilhelm, Barbara; Durst, Wilhelm; Trauzettel-Klosinski, Susanne; Zrenner, Eberhart

    A number of different technical devices for restoring vision in blind patients have been proposed to date. They employ different strategies for the acquisition of optical information, image processing, and electrical stimulation. Devices with external cameras or with integrated components for light detection have been developed and are designed to stimulate such different sites as the retina, optic nerve, and cortex. First clinical trials for these devices are being planned or already underway. As vision with these artificial vision devices (AVDs) may differ considerably from natural vision and as it may not be possible to predict visual functions provided by such devices on the basis of technical specifications alone, novel test strategies are needed to comprehensively describe visual performance. We propose a battery of tests for standardized well-controlled investigations in these patients that allow for objective assessment of efficacy of these devices.

  18. How does the extent of central visual field loss affect adaptive gait?

    PubMed

    Timmis, Matthew A; Scarfe, Amy C; Pardhan, Shahina

    2016-02-01

    Visual impairment is one of the most important clinical risk factors associated with falls. Currently it remains unclear whether adaptive gait is progressively affected as the extent of central visual field loss (CFL) increases, or when CFL exceeds a certain size. 10 participants (aged 22 ± 3 years) negotiated a floor based obstacle in full vision (no occlusion) and wearing custom made contact lenses which simulated 10° CFL and 20° CFL. Movement kinematics assessed the period immediately prior to and during obstacle crossing. In the 20° CFL condition, participants exhibited adaptations in gait which were consistent with being more cautious and more variable during the approach to and crossing of the obstacle, when compared to both 10° CFL and full vision conditions. Specifically, in the 20° CFL condition participants placed their lead foot further from the obstacle, lifted both their lead and trail feet higher and slower over the obstacle, and took longer to negotiate the obstacle when compared to the 10° CFL and full vision conditions. Data highlights differences in adaptive gait as a function of the extent of CFL when compared to full vision. More importantly, these adaptations were only associated with loss of the central 20° of the visual field, suggesting that gait is compromised only after central visual field loss exceeds a certain level.

  19. Coherent Image Layout using an Adaptive Visual Vocabulary

    SciTech Connect

    Dillard, Scott E.; Henry, Michael J.; Bohn, Shawn J.; Gosink, Luke J.

    2013-03-06

    When querying a huge image database containing millions of images, the result of the query may still contain many thousands of images that need to be presented to the user. We consider the problem of arranging such a large set of images into a visually coherent layout, one that places similar images next to each other. Image similarity is determined using a bag-of-features model, and the layout is constructed from a hierarchical clustering of the image set by mapping an in-order traversal of the hierarchy tree into a space-filling curve. This layout method provides strong locality guarantees so we are able to quantitatively evaluate performance using standard image retrieval benchmarks. Performance of the bag-of-features method is best when the vocabulary is learned on the image set being clustered. Because learning a large, discriminative vocabulary is a computationally demanding task, we present a novel method for efficiently adapting a generic visual vocabulary to a particular dataset. We evaluate our clustering and vocabulary adaptation methods on a variety of image datasets and show that adapting a generic vocabulary to a particular set of images improves performance on both hierarchical clustering and image retrieval tasks.

  20. Visualization for learners: a framework for adapting scientists' tools

    NASA Astrophysics Data System (ADS)

    Edelson, Daniel C.; Gordin, Douglas

    1998-08-01

    The use of scientific investigation tools for education is receiving considerable attention as a result of an increased emphasis in the educational community on open-ended inquiry. The scientific community possesses a treasure trove of tools that could be adapted for use by learners. Scientific visualization technologies, in particular, offer great promise for education because of the way they use visual representations to facilitate exploration of complex data. However, the tools that are used by scientists are inappropriate for learners because of their reliance on the tacit knowledge of expert users. Through a careful consideration of the differences between scientists and science students and the design of a series of scientific visualization environments for learners in grades 8-16, we have developed a design framework for the creation of scientific investigation tools based on those of scientists. The framework highlights five critical issues for the construction of tools to support inquiry-based learning: motivating context, learner-appropriate activities, data selection, scaffolding interfaces and support for learning. We have applied this framework to the design of ClimateWatcher, a scientific visualization environment for the investigation of issues related to global climate and climate change that is now in use in middle school, high school and university settings.

  1. Measurements of contrast sensitivity by an adaptive optics visual simulator

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tatsuo; Ucikawa, Keiji

    2015-08-01

    We developed an adaptive optics visual simulator (AOVS) to study the relationship between the contrast sensitivity and higher-order wavefront aberrations of human eyes. A desired synthetic aberration was virtually generated on a subject eye by the AOVS, and red laser light was used to measure the aberrations. The contrast sensitivity was measured in a psychophysical experiment using visual stimulus patterns provided by a large-contrast-range imaging system, which included two liquid crystal displays illuminated by red light emitting diodes from the backside. The diameter of the pupil was set to 4 mm by an artificial aperture, and the retinal illuminance of the stimulus image was controlled to 10 Td. Experiments conducted with four normal subjects revealed that their contrast sensitivity to a high-spatial-frequency vertical sinusoidal grating pattern was lower in the presence of a horizontal coma aberration than in the presence of a vertical coma or no aberrations ( p < 0.02, Nagai method).

  2. Visualization of Octree Adaptive Mesh Refinement (AMR) in Astrophysical Simulations

    NASA Astrophysics Data System (ADS)

    Labadens, M.; Chapon, D.; Pomaréde, D.; Teyssier, R.

    2012-09-01

    Computer simulations are important in current cosmological research. Those simulations run in parallel on thousands of processors, and produce huge amount of data. Adaptive mesh refinement is used to reduce the computing cost while keeping good numerical accuracy in regions of interest. RAMSES is a cosmological code developed by the Commissariat à l'énergie atomique et aux énergies alternatives (English: Atomic Energy and Alternative Energies Commission) which uses Octree adaptive mesh refinement. Compared to grid based AMR, the Octree AMR has the advantage to fit very precisely the adaptive resolution of the grid to the local problem complexity. However, this specific octree data type need some specific software to be visualized, as generic visualization tools works on Cartesian grid data type. This is why the PYMSES software has been also developed by our team. It relies on the python scripting language to ensure a modular and easy access to explore those specific data. In order to take advantage of the High Performance Computer which runs the RAMSES simulation, it also uses MPI and multiprocessing to run some parallel code. We would like to present with more details our PYMSES software with some performance benchmarks. PYMSES has currently two visualization techniques which work directly on the AMR. The first one is a splatting technique, and the second one is a custom ray tracing technique. Both have their own advantages and drawbacks. We have also compared two parallel programming techniques with the python multiprocessing library versus the use of MPI run. The load balancing strategy has to be smartly defined in order to achieve a good speed up in our computation. Results obtained with this software are illustrated in the context of a massive, 9000-processor parallel simulation of a Milky Way-like galaxy.

  3. Noise Adaptive Stream Weighting in Audio-Visual Speech Recognition

    NASA Astrophysics Data System (ADS)

    Heckmann, Martin; Berthommier, Frédéric; Kroschel, Kristian

    2002-12-01

    It has been shown that integration of acoustic and visual information especially in noisy conditions yields improved speech recognition results. This raises the question of how to weight the two modalities in different noise conditions. Throughout this paper we develop a weighting process adaptive to various background noise situations. In the presented recognition system, audio and video data are combined following a Separate Integration (SI) architecture. A hybrid Artificial Neural Network/Hidden Markov Model (ANN/HMM) system is used for the experiments. The neural networks were in all cases trained on clean data. Firstly, we evaluate the performance of different weighting schemes in a manually controlled recognition task with different types of noise. Next, we compare different criteria to estimate the reliability of the audio stream. Based on this, a mapping between the measurements and the free parameter of the fusion process is derived and its applicability is demonstrated. Finally, the possibilities and limitations of adaptive weighting are compared and discussed.

  4. Visual function with acupuncture tested by visual evoked potential.

    PubMed

    Sagara, Yoshiko; Fuse, Nobuo; Seimiya, Motohiko; Yokokura, Syunji; Watanabe, Kei; Nakazawa, Toru; Kurusu, Masayuki; Seki, Takashi; Tamai, Makoto

    2006-07-01

    Visual evoked potential (VEP) testing is used frequently and is an important ophthalmologic physiological test to examine visual functions objectively. The VEP is a complicated waveform consisting of negative waveform named N75 and N135, and positive waveform named P100. Delayed P100 latency and greatly attenuated amplitude on VEP are known characteristics for diagnosing optic nerve disease. Acupuncture has been used to treat wide clinical symptoms with minimal side effects. The confirmation of the efficacy of acupuncture generally relies on subjective symptoms. There is not much scientific evidence supporting the acupuncture treatments for eye diseases up to today. However, the VEP test can evaluate objectively and numerically the efficacy of the treatment by the acupuncture. We analyzed 19 healthy subjects (38 eyes). The P100 latencies in the group of less than 101.7 msec (total average) before acupuncture stimulations were not different than those after treatment (98.2 +/- 3.0 msec, 98.2 +/- 4.0 msec, respectively, p = 0.88, n = 17), but the latencies in those subjects with longer or equal to 101.7 msec were statistically different after acupuncture (104.6 +/- 2.8 msec, 101.9 +/- 3.7 msec, respectively, p = 0.006, n = 21). These results show that the acupuncture stimulation contributes to the P100 latencies of pattern reversal (PR)-VEP to some subjects who have delayed latencies, and this electrophysiological method is a valuable technique in monitoring the effectiveness of acupuncture therapy in the improvements of visual functions. The purpose of this study is to evaluate the physiological effects by acupuncture stimulations using PR-VEP in normal subjects.

  5. Visual Scenes are Categorized by Function

    PubMed Central

    Greene, Michelle R.; Baldassano, Christopher; Esteva, Andre; Beck, Diane M.; Fei-Fei, Li

    2015-01-01

    How do we know that a kitchen is a kitchen by looking? Traditional models posit that scene categorization is achieved through recognizing necessary and sufficient features and objects, yet there is little consensus about what these may be. However, scene categories should reflect how we use visual information. We therefore test the hypothesis that scene categories reflect functions, or the possibilities for actions within a scene. Our approach is to compare human categorization patterns with predictions made by both functions and alternative models. We collected a large-scale scene category distance matrix (5 million trials) by asking observers to simply decide whether two images were from the same or different categories. Using the actions from the American Time Use Survey, we mapped actions onto each scene (1.4 million trials). We found a strong relationship between ranked category distance and functional distance (r=0.50, or 66% of the maximum possible correlation). The function model outperformed alternative models of object-based distance (r=0.33), visual features from a convolutional neural network (r=0.39), lexical distance (r=0.27), and models of visual features. Using hierarchical linear regression, we found that functions captured 85.5% of overall explained variance, with nearly half of the explained variance captured only by functions, implying that the predictive power of alternative models was due to their shared variance with the function-based model. These results challenge the dominant school of thought that visual features and objects are sufficient for scene categorization, suggesting instead that a scene’s category may be determined by the scene’s function. PMID:26709590

  6. Visual determination of differential renal function

    SciTech Connect

    Kipper, M.S.; Witztum, K.F.; Taylor, A. Jr.

    1986-05-01

    Forty patients (43 studies) referred for determination of differential renal function were imaged 24 hours after intravenous administration of Tc-99m-2, 3 DMSA. Visual assessment of relative renal uptake was estimated independently by three observers at three different hospitals from analog images on standard x-ray film. The results were compared with the relative DMSA uptake obtained by summing counts in computer-assisted regions of interest placed over each kidney. There was excellent correlation between the visual estimates of each observer and the computer-generated values (r = 0.98, 0.96, and 0.98, respectively). If a computer is not available, good visual estimates of differential uptake still may be obtained when static imaging agents such as DMSA are administered.

  7. Adaptive integration in the visual cortex by depressing recurrent cortical circuits.

    PubMed

    van Rossum, Mark C W; van der Meer, Matthijs A A; Xiao, Dengke; Oram, Mike W

    2008-07-01

    Neurons in the visual cortex receive a large amount of input from recurrent connections, yet the functional role of these connections remains unclear. Here we explore networks with strong recurrence in a computational model and show that short-term depression of the synapses in the recurrent loops implements an adaptive filter. This allows the visual system to respond reliably to deteriorated stimuli yet quickly to high-quality stimuli. For low-contrast stimuli, the model predicts long response latencies, whereas latencies are short for high-contrast stimuli. This is consistent with physiological data showing that in higher visual areas, latencies can increase more than 100 ms at low contrast compared to high contrast. Moreover, when presented with briefly flashed stimuli, the model predicts stereotypical responses that outlast the stimulus, again consistent with physiological findings. The adaptive properties of the model suggest that the abundant recurrent connections found in visual cortex serve to adapt the network's time constant in accordance with the stimulus and normalizes neuronal signals such that processing is as fast as possible while maintaining reliability.

  8. Adaptive Behavior of Primary School Students with Visual Impairments: The Impact of Educational Settings

    ERIC Educational Resources Information Center

    Metsiou, Katerina; Papadopoulos, Konstantinos; Agaliotis, Ioannis

    2011-01-01

    This study explored the adaptive behavior of primary school students with visual impairments, as well as the impact of educational setting on their adaptive behavior. Instrumentation included an informal questionnaire and the Vineland Adaptive Behavior Scales. Participants were 36 primary school students with visual impairments. The educational…

  9. Pain's Impact on Adaptive Functioning

    ERIC Educational Resources Information Center

    Breau, L. M.; Camfield, C. S.; McGrath, P. J.; Finley, G. A.

    2007-01-01

    Background: Pain interferes with the functioning of typical children, but no study has examined its effect on children with pre-existing intellectual disabilities (ID). Methods: Caregivers of 63 children observed their children for 2-h periods and recorded in 1-week diaries: pain presence, cause, intensity and duration. Caregivers also recorded…

  10. Seeing a haptically explored face: visual facial-expression aftereffect from haptic adaptation to a face.

    PubMed

    Matsumiya, Kazumichi

    2013-10-01

    Current views on face perception assume that the visual system receives only visual facial signals. However, I show that the visual perception of faces is systematically biased by adaptation to a haptically explored face. Recently, face aftereffects (FAEs; the altered perception of faces after adaptation to a face) have been demonstrated not only in visual perception but also in haptic perception; therefore, I combined the two FAEs to examine whether the visual system receives face-related signals from the haptic modality. I found that adaptation to a haptically explored facial expression on a face mask produced a visual FAE for facial expression. This cross-modal FAE was not due to explicitly imaging a face, response bias, or adaptation to local features. Furthermore, FAEs transferred from vision to haptics. These results indicate that visual face processing depends on substrates adapted by haptic faces, which suggests that face processing relies on shared representation underlying cross-modal interactions.

  11. Visual Function Changes after Laser Exposure.

    DTIC Science & Technology

    1984-04-01

    change in the pigment epithelium or the bipolar or ganglion cells of the inner retina was detectable. While these investigations (6, 7, 8) suggest a good...present initially after intense levels of light exposure (24- 26). Long-term followup of visual acuity (6 mo) after solar -induced foveal damage (27... cell . The possibility that this alteration is involved with a complex and subtle retinal photoreceptor alignment function is only speculation at this

  12. Which visual functions depend on intermediate visual regions? Insights from a case of developmental visual form agnosia.

    PubMed

    Gilaie-Dotan, Sharon

    2016-03-01

    A key question in visual neuroscience is the causal link between specific brain areas and perceptual functions; which regions are necessary for which visual functions? While the contribution of primary visual cortex and high-level visual regions to visual perception has been extensively investigated, the contribution of intermediate visual areas (e.g. V2/V3) to visual processes remains unclear. Here I review more than 20 visual functions (early, mid, and high-level) of LG, a developmental visual agnosic and prosopagnosic young adult, whose intermediate visual regions function in a significantly abnormal fashion as revealed through extensive fMRI and ERP investigations. While expectedly, some of LG's visual functions are significantly impaired, some of his visual functions are surprisingly normal (e.g. stereopsis, color, reading, biological motion). During the period of eight-year testing described here, LG trained on a perceptual learning paradigm that was successful in improving some but not all of his visual functions. Following LG's visual performance and taking into account additional findings in the field, I propose a framework for how different visual areas contribute to different visual functions, with an emphasis on intermediate visual regions. Thus, although rewiring and plasticity in the brain can occur during development to overcome and compensate for hindering developmental factors, LG's case seems to indicate that some visual functions are much less dependent on strict hierarchical flow than others, and can develop normally in spite of abnormal mid-level visual areas, thereby probably less dependent on intermediate visual regions.

  13. The Role of Adaptive Supplemental Visual Cuing in Flight Simulation.

    DTIC Science & Technology

    1987-01-01

    aircrif!t S-1 a3o em J) e by in .re vi Aer" "yne foris eoo -., Doto f the a .ro raf t before learnin of 1!; 3p~ 1 1 e t a 3K, part ic,:larly perceptual...77-A195 932 THE ROLE OF ADAPTIVE SUPPLEMENTAL VISUAL CUING IN t/1 FLIGHT 5IMULRTION(U) AIR FORCE INST OF TECH WRIGHT-PATTERSONAFA OH E RBBILLMAN 1987...UNCLASSIFIED AF T/CI/NR-8 -iB6T F/G 5/9 UL E ,7hEcE7hEhhhhEEohEohhE EhhhhmmhhohhE _ _ , -,,.ah. .- ’-, - .. - ’ . ’ -~ ..V .. _ .. ,,. . . , ,,VW Y W

  14. Adaptive color visualization for dichromats using a customized hierarchical palette

    NASA Astrophysics Data System (ADS)

    Rodríguez-Pardo, Carlos E.; Sharma, Gaurav

    2011-01-01

    We propose a user-centric methodology for displaying digital color documents, that optimizes color representations in an observer specific and adaptive fashion. We apply our framework to situations involving viewers with common dichromatic color vision deficiencies, who face challenges in perceiving information presented in color images and graphics designed for color normal individuals. For situations involving qualitative data visualization, we present a computationally efficient solution that combines a customized observer-specific hierarchical palette with "display time" selection of the number of colors to generate renderings with colors that are easily discriminated by the intended viewer. The palette design is accomplished via a clustering algorithm, that arranges colors in a hierarchical tree based on their perceived differences for the intended viewer. A desired number of highly discriminable colors are readily obtained from the hierarchical palette via a simple truncation. As an illustration, we demonstrate the application of the methodology to Ishihara style images.

  15. Some Aspects of Visual Processing Under Chromatic Adaptation.

    NASA Astrophysics Data System (ADS)

    Wilson, Julie Ann Frances

    Available from UMI in association with The British Library. This thesis describes the results of experimental investigations into three types of visual processing, namely, displacement thresholds for motion detection, speed and motion detection, and rod-cone interaction effects. Each of these topics is described separately. The overall conclusions and summary of this work with an emphasis on chromatic processes are presented in the last chapter. The introductory chapter of the thesis deals mostly with the anatomical and theoretical aspects of vision and the development of a system for the standardization of colour. Equations for the CIE colour and colour difference specifications are described. Equipment, optical apparatus and general calibration procedures for all the investigations are covered in Chapter Two. Displacement thresholds for motion detection under conditions of chromatic adaptation are the subject of Chapter Three. The smallest, continuous target displacement sufficient to cause a sensation of movement was measured under conditions of chromatic adaptation. The experiments were carried out for test target and background field wavelengths which selectively isolated the activity of the colour mechanisms of the human eye. In Chapter Four, two mechanisms capable of speed discrimination and motion detection are proposed. Experimental data are reported which suggest that the visual system employs both schemes. A small circular target of high retinal illuminance level can have a comet-like appearance when presented moving continuously with a speed as low as 0.2 deg/s. Data on the parametric properties of the 'comet effect' are presented in Chapter Five. Measurement of the target spectral irradiance levels sufficient to yield the 'comet effect' suggests that the lengthening of the circular target reflects a rod-cone interaction and therefore it may be due to unsuppressed, saturated rod responses at high retinal illuminance levels. Computational methods are

  16. Molecular ecology and adaptation of visual photopigments in craniates.

    PubMed

    Davies, Wayne I L; Collin, Shaun P; Hunt, David M

    2012-07-01

    In craniates, opsin-based photopigments expressed in the eye encode molecular 'light sensors' that constitute the initial protein in photoreception and the activation of the phototransduction cascade. Since the cloning and sequencing of the first vertebrate opsin gene (bovine rod opsin) nearly 30 years ago (Ovchinnikov Yu 1982, FEBS Letters, 148, 179-191; Hargrave et al. 1983, Biophysics of Structure & Mechanism, 9, 235-244; Nathans & Hogness 1983, Cell, 34, 807-814), it is now well established that variation in the subtypes and spectral properties of the visual pigments that mediate colour and dim-light vision is a prevalent mechanism for the molecular adaptation to diverse light environments. In this review, we discuss the origins and spectral tuning of photopigments that first arose in the agnathans to sample light within the ancient aquatic landscape of the Early Cambrian, detailing the molecular changes that subsequently occurred in each of the opsin classes independently within the main branches of extant jawed gnathostomes. Specifically, we discuss the adaptive changes that have occurred in the photoreceptors of craniates as they met the ecological challenges to survive in quite differing photic niches, including brightly lit aquatic surroundings; the deep sea; the transition to and from land; diurnal, crepuscular and nocturnal environments; and light-restricted fossorial settings. The review ends with a discussion of the limitations inherent to the 'nocturnal-bottleneck' hypothesis relevant to the evolution of the mammalian visual system and a proposition that transition through a 'mesopic-bottleneck' may be a more appropriate model.

  17. Spatio-temporal dynamics of adaptation in the human visual system: a high-density electrical mapping study.

    PubMed

    Andrade, Gizely N; Butler, John S; Mercier, Manuel R; Molholm, Sophie; Foxe, John J

    2015-04-01

    When sensory inputs are presented serially, response amplitudes to stimulus repetitions generally decrease as a function of presentation rate, diminishing rapidly as inter-stimulus intervals (ISIs) fall below 1 s. This 'adaptation' is believed to represent mechanisms by which sensory systems reduce responsivity to consistent environmental inputs, freeing resources to respond to potentially more relevant inputs. While auditory adaptation functions have been relatively well characterized, considerably less is known about visual adaptation in humans. Here, high-density visual-evoked potentials (VEPs) were recorded while two paradigms were used to interrogate visual adaptation. The first presented stimulus pairs with varying ISIs, comparing VEP amplitude to the second stimulus with that of the first (paired-presentation). The second involved blocks of stimulation (N = 100) at various ISIs and comparison of VEP amplitude between blocks of differing ISIs (block-presentation). Robust VEP modulations were evident as a function of presentation rate in the block-paradigm, with strongest modulations in the 130-150 ms and 160-180 ms visual processing phases. In paired-presentations, with ISIs of just 200-300 ms, an enhancement of VEP was evident when comparing S2 with S1, with no significant effect of presentation rate. Importantly, in block-presentations, adaptation effects were statistically robust at the individual participant level. These data suggest that a more taxing block-presentation paradigm is better suited to engage visual adaptation mechanisms than a paired-presentation design. The increased sensitivity of the visual processing metric obtained in the block-paradigm has implications for the examination of visual processing deficits in clinical populations.

  18. Visual enhancement of unmixed multispectral imagery using adaptive smoothing

    USGS Publications Warehouse

    Lemeshewsky, G.P.; Rahman, Z.-U.; Schowengerdt, R.A.; Reichenbach, S.E.

    2004-01-01

    Adaptive smoothing (AS) has been previously proposed as a method to smooth uniform regions of an image, retain contrast edges, and enhance edge boundaries. The method is an implementation of the anisotropic diffusion process which results in a gray scale image. This paper discusses modifications to the AS method for application to multi-band data which results in a color segmented image. The process was used to visually enhance the three most distinct abundance fraction images produced by the Lagrange constraint neural network learning-based unmixing of Landsat 7 Enhanced Thematic Mapper Plus multispectral sensor data. A mutual information-based method was applied to select the three most distinct fraction images for subsequent visualization as a red, green, and blue composite. A reported image restoration technique (partial restoration) was applied to the multispectral data to reduce unmixing error, although evaluation of the performance of this technique was beyond the scope of this paper. The modified smoothing process resulted in a color segmented image with homogeneous regions separated by sharpened, coregistered multiband edges. There was improved class separation with the segmented image, which has importance to subsequent operations involving data classification.

  19. Visual discrimination and adaptation using non-linear unsupervised learning

    NASA Astrophysics Data System (ADS)

    Jiménez, Sandra; Laparra, Valero; Malo, Jesus

    2013-03-01

    Understanding human vision not only involves empirical descriptions of how it works, but also organization principles that explain why it does so. Identifying the guiding principles of visual phenomena requires learning algorithms to optimize specific goals. Moreover, these algorithms have to be flexible enough to account for the non-linear and adaptive behavior of the system. For instance, linear redundancy reduction transforms certainly explain a wide range of visual phenomena. However, the generality of this organization principle is still in question:10 it is not only that and additional constraints such as energy cost may be relevant as well, but also, statistical independence may not be the better solution to make optimal inferences in squared error terms. Moreover, linear methods cannot account for the non-uniform discrimination in different regions of the image and color space: linear learning methods necessarily disregard the non-linear nature of the system. Therefore, in order to account for the non-linear behavior, principled approaches commonly apply the trick of using (already non-linear) parametric expressions taken from empirical models. Therefore these approaches are not actually explaining the non-linear behavior, but just fitting it to image statistics. In summary, a proper explanation of the behavior of the system requires flexible unsupervised learning algorithms that (1) are tunable to different, perceptually meaningful, goals; and (2) make no assumption on the non-linearity. Over the last years we have worked on these kind of learning algorithms based on non-linear ICA,18 Gaussianization, 19 and principal curves. In this work we stress the fact that these methods can be tuned to optimize different design strategies, namely statistical independence, error minimization under quantization, and error minimization under truncation. Then, we show (1) how to apply these techniques to explain a number of visual phenomena, and (2) suggest the

  20. Oculomotor Adaptation Elicited By Intra-Saccadic Visual Stimulation: Time-Course of Efficient Visual Target Perturbation.

    PubMed

    Panouillères, Muriel T N; Gaveau, Valerie; Debatisse, Jeremy; Jacquin, Patricia; LeBlond, Marie; Pélisson, Denis

    2016-01-01

    Perception of our visual environment strongly depends on saccadic eye movements, which in turn are calibrated by saccadic adaptation mechanisms elicited by systematic movement errors. Current models of saccadic adaptation assume that visual error signals are acquired only after saccade completion, because the high speed of saccade execution disturbs visual processing (saccadic "suppression" and "mislocalization"). Complementing a previous study from our group, here we report that visual information presented during saccades can drive adaptation mechanisms and we further determine the critical time window of such error processing. In 15 healthy volunteers, shortening adaptation of reactive saccades toward a ±8° visual target was induced by flashing the target for 2 ms less eccentrically than its initial location either near saccade peak velocity ("PV" condition) or peak deceleration ("PD") or saccade termination ("END"). Results showed that, as compared to the "CONTROL" condition (target flashed at its initial location upon saccade termination), saccade amplitude decreased all throughout the "PD" and "END" conditions, reaching significant levels in the second adaptation and post-adaptation blocks. The results of nine other subjects tested in a saccade lengthening adaptation paradigm with the target flashing near peak deceleration ("PD" and "CONTROL" conditions) revealed no significant change of gain, confirming that saccade shortening adaptation is easier to elicit. Also, together with this last result, the stable gain observed in the "CONTROL" conditions of both experiments suggests that mislocalization of the target flash is not responsible for the saccade shortening adaptation demonstrated in the first group. Altogether, these findings reveal that the visual "suppression" and "mislocalization" phenomena related to saccade execution do not prevent brief visual information delivered "in-flight" from being processed to elicit oculomotor adaptation.

  1. [Functional examinations of visual channels: physiological basis].

    PubMed

    Zueva, M V; Tsapenko, I V; Lantukh, E P; Maglakelidze, N M

    2017-01-01

    In this paper, technical details of visual evoked potentials (VEP) assessment and pattern electroretinography (PERG) are reviewed. Both methods are used to perform an objective functional examination of visual channels and to clarify the level, at which they have been damaged. Contributions of parvo- (P), magno- (M) and koniocellular (K) systems to the morphology of PERG and VEP responses are discussed with account to test conditions, selectively supportive of the activity of particular cell populations. The review analyzes the physiological role of such stimulation parameters as brightness and color contrast of the pattern elements as well as spatial and temporal frequency in detecting dysfunction of color channels and mistuning of the P- and M- pathways. Different times taken for neuronal integration and signal conduction along the M- and P- pathways determine the timing of the P- and M- VEP components, allowing us to judge their contribution to VEP morphology from the same recording.

  2. Night Myopia Studied with an Adaptive Optics Visual Analyzer

    PubMed Central

    Artal, Pablo; Schwarz, Christina; Cánovas, Carmen; Mira-Agudelo, Alejandro

    2012-01-01

    Purpose Eyes with distant objects in focus in daylight are thought to become myopic in dim light. This phenomenon, often called “night myopia” has been studied extensively for several decades. However, despite its general acceptance, its magnitude and causes are still controversial. A series of experiments were performed to understand night myopia in greater detail. Methods We used an adaptive optics instrument operating in invisible infrared light to elucidate the actual magnitude of night myopia and its main causes. The experimental setup allowed the manipulation of the eye's aberrations (and particularly spherical aberration) as well as the use of monochromatic and polychromatic stimuli. Eight subjects with normal vision monocularly determined their best focus position subjectively for a Maltese cross stimulus at different levels of luminance, from the baseline condition of 20 cd/m2 to the lowest luminance of 22×10−6 cd/m2. While subjects performed the focusing tasks, their eye's defocus and aberrations were continuously measured with the 1050-nm Hartmann-Shack sensor incorporated in the adaptive optics instrument. The experiment was repeated for a variety of controlled conditions incorporating specific aberrations of the eye and chromatic content of the stimuli. Results We found large inter-subject variability and an average of −0.8 D myopic shift for low light conditions. The main cause responsible for night myopia was the accommodation shift occurring at low light levels. Other factors, traditionally suggested to explain night myopia, such as chromatic and spherical aberrations, have a much smaller effect in this mechanism. Conclusions An adaptive optics visual analyzer was applied to study the phenomenon of night myopia. We found that the defocus shift occurring in dim light is mainly due to accommodation errors. PMID:22768343

  3. Adaptation-induced modification of motion selectivity tuning in visual tectal neurons of adult zebrafish

    PubMed Central

    Lucks, Valerie; Kurtz, Rafael; Engelmann, Jacob

    2015-01-01

    In the developing brain, training-induced emergence of direction selectivity and plasticity of orientation tuning appear to be widespread phenomena. These are found in the visual pathway across different classes of vertebrates. Moreover, short-term plasticity of orientation tuning in the adult brain has been demonstrated in several species of mammals. However, it is unclear whether neuronal orientation and direction selectivity in nonmammalian species remains modifiable through short-term plasticity in the fully developed brain. To address this question, we analyzed motion tuning of neurons in the optic tectum of adult zebrafish by calcium imaging. In total, orientation and direction selectivity was enhanced by adaptation, responses of previously orientation-selective neurons were sharpened, and even adaptation-induced emergence of selectivity in previously nonselective neurons was observed in some cases. The different observed effects are mainly based on the relative distance between the previously preferred and the adaptation direction. In those neurons in which a shift of the preferred orientation or direction was induced by adaptation, repulsive shifts (i.e., away from the adapter) were more prevalent than attractive shifts. A further novel finding for visually induced adaptation that emerged from our study was that repulsive and attractive shifts can occur within one brain area, even with uniform stimuli. The type of shift being induced also depends on the difference between the adapting and the initially preferred stimulus direction. Our data indicate that, even within the fully developed optic tectum, short-term plasticity might have an important role in adjusting neuronal tuning functions to current stimulus conditions. PMID:26378206

  4. Effect of Microgravity on Several Visual Functions During STS Shuttle Missions: Visual Function Tester-model 1 (VFT-1)

    NASA Technical Reports Server (NTRS)

    Oneal, Melvin R.; Task, H. Lee; Genco, Louis V.

    1992-01-01

    Viewgraphs on the effect of microgravity on several visual functions during STS shuttle missions are presented. The purpose, methods, results, and discussion are discussed. The visual function tester model 1 is used.

  5. Spatio-temporal dynamics of adaptation in the human visual system: A high-density electrical mapping study

    PubMed Central

    Andrade, Gizely N.; Butler, John S.; Mercier, Manuel R.; Molholm, Sophie; Foxe, John J.

    2015-01-01

    When sensory inputs are presented serially, response amplitudes to stimulus repetitions generally decrease as a function of presentation rate, diminishing rapidly as inter-stimulus-intervals (ISIs) fall below a second. This “adaptation” is believed to represent mechanisms by which sensory systems reduce responsivity to consistent environmental inputs, freeing resources to respond to potentially more relevant inputs. While auditory adaptation functions have been relatively well-characterized, considerably less is known about visual adaptation in humans. Here, high-density visual evoked potentials (VEPs) were recorded while two paradigms were used to interrogate visual adaptation. The first presented stimulus pairs with varying ISIs, comparing VEP amplitude to the second stimulus to that of the first (paired-presentation). The second involved blocks of stimulation (N=100) at various ISIs and comparison of VEP amplitude between blocks of differing ISIs (block-presentation). Robust VEP modulations were evident as a function of presentation rate in the block-paradigm with strongest modulations in the 130–150ms and 160–180ms visual processing phases. In paired-presentations, with ISIs of just 200–300 ms, an enhancement of VEP was evident when comparing S2 to S1, with no significant effect of presentation rate. Importantly, in block-presentations, adaptation effects were statistically robust at the individual participant level. These data suggest that a more taxing block-presentation paradigm is better suited to engage visual adaptation mechanisms than a paired-presentation design. The increased sensitivity of the visual processing metric obtained in the block-paradigm has implications for the examination of visual processing deficits in clinical populations. PMID:25688539

  6. Developmental functional adaptation to high altitude: review.

    PubMed

    Frisancho, A Roberto

    2013-01-01

    Various approaches have been used to understand the origins of the functional traits that characterize the Andean high-altitude native. Based on the conceptual framework of developmental functional adaptation which postulates that environmental influences during the period of growth and development have long lasting effects that may be expressed during adulthood, we initiated a series of studies addressed at determining the pattern of physical growth and the contribution of growth and development to the attainment of full functional adaptation to high-altitude of low and high altitude natives living under rural and urban conditions. Current research indicate that: (a) the pattern of growth at high altitude due to limited nutritional resources, physical growth in body size is delayed but growth in lung volumes is accelerated because of hypoxic stress); (b) low-altitude male and female urban natives can attain a full functional adaptation to high altitude by exposure to high-altitude hypoxia during the period of growth and development; (c) both experimental studies on animals and comparative human studies indicate that exposure to high altitude during the period of growth and development results in the attainment of a large residual lung volume; (d) this developmentally acquired enlarged residual lung volume and its associated increase in alveolar area when combined with the increased tissue capillarization and moderate increase in red blood cells and hemoglobin concentration contributes to the successful functional adaptation of the Andean high-altitude native to hypoxia; and (e) any specific genetic traits that are related to the successful functional adaptation of Andean high-altitude natives have yet to be identified.

  7. Functional and cortical adaptations to central vision loss

    PubMed Central

    CHEUNG, SING-HANG; LEGGE, GORDON E.

    2005-01-01

    Age-related macular degeneration (AMD), affecting the retina, afflicts one out of ten people aged 80 years or older in the United States. AMD often results in vision loss to the central 15–20 deg of the visual field (i.e. central scotoma), and frequently afflicts both eyes. In most cases, when the central scotoma includes the fovea, patients will adopt an eccentric preferred retinal locus (PRL) for fixation. The onset of a central scotoma results in the absence of retinal inputs to corresponding regions of retinotopically mapped visual cortex. Animal studies have shown evidence for reorganization in adult mammals for such cortical areas following experimentally induced central scotomata. However, it is still unknown whether reorganization occurs in primary visual cortex (V1) of AMD patients. Nor is it known whether the adoption of a PRL corresponds to changes to the retinotopic mapping of V1. Two recent advances hold out the promise for addressing these issues and for contributing to the rehabilitation of AMD patients: improved methods for assessing visual function across the fields of AMD patients using the scanning laser ophthalmoscope, and the advent of brain-imaging methods for studying retinotopic mapping in humans. For the most part, specialists in these two areas come from different disciplines and communities, with few opportunities to interact. The purpose of this review is to summarize key findings on both the clinical and neuroscience issues related to questions about visual adaptation in AMD patients. PMID:15935111

  8. Adaptation to visual feedback delay in a redundant motor task.

    PubMed

    Farshchiansadegh, Ali; Ranganathan, Rajiv; Casadio, Maura; Mussa-Ivaldi, Ferdinando A

    2015-01-15

    The goal of this study was to examine the reorganization of hand movements during adaptation to delayed visual feedback in a novel and redundant environment. In most natural behaviors, the brain must learn to invert a many-to-one map from high-dimensional joint movements and muscle forces to a low-dimensional goal. This spatial "inverse map" is learned by associating motor commands to their low-dimensional consequences. How is this map affected by the presence of temporal delays? A delay presents the brain with a new set of kinematic data, and, because of redundancy, the brain may use these data to form a new inverse map. We consider two possible responses to a novel visuomotor delay. In one case, the brain updates the previously learned spatial map, building a new association between motor commands and visual feedback of their effects. In the alternative case, the brain preserves the original map and learns to compensate the delay by a temporal shift of the motor commands. To test these alternative possibilities, we developed a virtual reality game in which subjects controlled the two-dimensional coordinates of a cursor by continuous hand gestures. Two groups of subjects tracked a target along predictable paths by wearing an instrumented data glove that recorded finger motions. The 19-dimensional glove signals controlled a cursor on a 2-dimensional computer display. The experiment was performed on 2 consecutive days. On the 1st day, subjects practiced tracking movements without delay. On the 2nd day, the test group performed the same task with a delay of 300 ms between the glove signals and the cursor display, whereas the control group continued practicing the nondelayed trials. We found evidence that to compensate for the delay, the test group relied on the coordination patterns established during the baseline, e.g., their hand-to-cursor inverse map was robust to the delay perturbation, which was counteracted by an anticipation of the motor command.

  9. Adaptation of the human visual system to the statistics of letters and line configurations.

    PubMed

    Chang, Claire H C; Pallier, Christophe; Wu, Denise H; Nakamura, Kimihiro; Jobert, Antoinette; Kuo, W-J; Dehaene, Stanislas

    2015-10-15

    By adulthood, literate humans have been exposed to millions of visual scenes and pages of text. Does the human visual system become attuned to the statistics of its inputs? Using functional magnetic resonance imaging, we examined whether the brain responses to line configurations are proportional to their natural-scene frequency. To further distinguish prior cortical competence from adaptation induced by learning to read, we manipulated whether the selected configurations formed letters and whether they were presented on the horizontal meridian, the familiar location where words usually appear, or on the vertical meridian. While no natural-scene frequency effect was observed, we observed letter-status and letter frequency effects on bilateral occipital activation, mainly for horizontal stimuli. The findings suggest a reorganization of the visual pathway resulting from reading acquisition under genetic and connectional constraints. Even early retinotopic areas showed a stronger response to letters than to rotated versions of the same shapes, suggesting an early visual tuning to large visual features such as letters.

  10. Adaptive Neurotechnology for Making Neural Circuits Functional .

    NASA Astrophysics Data System (ADS)

    Jung, Ranu

    2008-03-01

    Two of the most important trends in recent technological developments are that technology is increasingly integrated with biological systems and that it is increasingly adaptive in its capabilities. Neuroprosthetic systems that provide lost sensorimotor function after a neural disability offer a platform to investigate this interplay between biological and engineered systems. Adaptive neurotechnology (hardware and software) could be designed to be biomimetic, guided by the physical and programmatic constraints observed in biological systems, and allow for real-time learning, stability, and error correction. An example will present biomimetic neural-network hardware that can be interfaced with the isolated spinal cord of a lower vertebrate to allow phase-locked real-time neural control. Another will present adaptive neural network control algorithms for functional electrical stimulation of the peripheral nervous system to provide desired movements of paralyzed limbs in rodents or people. Ultimately, the frontier lies in being able to utilize the adaptive neurotechnology to promote neuroplasticity in the living system on a long-time scale under co-adaptive conditions.

  11. Adaptive functional systems: learning with chaos.

    PubMed

    Komarov, M A; Osipov, G V; Burtsev, M S

    2010-12-01

    We propose a new model of adaptive behavior that combines a winnerless competition principle and chaos to learn new functional systems. The model consists of a complex network of nonlinear dynamical elements producing sequences of goal-directed actions. Each element describes dynamics and activity of the functional system which is supposed to be a distributed set of interacting physiological elements such as nerve or muscle that cooperates to obtain certain goal at the level of the whole organism. During "normal" behavior, the dynamics of the system follows heteroclinic channels, but in the novel situation chaotic search is activated and a new channel leading to the target state is gradually created simulating the process of learning. The model was tested in single and multigoal environments and had demonstrated a good potential for generation of new adaptations.

  12. Executive functioning and visual working memory.

    PubMed

    Lepach, Anja C; Pauls, Franz; Petermann, Franz

    2015-01-01

    The matter of modality is controversially discussed in the context of working memory (WM). There is evidence that modality-specific processes are accompanied by amodal processes to some extent. We investigated the relationship between executive-functioning tasks and visual WM (VWM) and were especially interested in the issue of amodal processes. Our correlational analyses suggest modality-independent relations of the tasks. We also aimed to quantify to what extent executive functioning is meaningful for VWM performances. We therefore estimated the relationship between executive tasks and VWM performances in a healthy (n = 710) and a clinical traumatic brain injury sample (n = 151) as well as in the combined total sample. The results indicate a substantial relevance of the verbal task for VWM performances in the total and the clinical sample but a low relevance in the healthy sample. These results could support assumptions of resource-depending differences in the relations of executive functioning and VWM but need further validation due to limitations of our study.

  13. About turn: the visual representation of human body orientation revealed by adaptation.

    PubMed

    Lawson, Rebecca P; Clifford, Colin W G; Calder, Andrew J

    2009-03-01

    Body orientation provides an important cue to other individuals' focus of attention, particularly when one is viewing them at a distance. Single-cell recording in macaques has identified cells in the superior temporal sulcus that show a view-selective response to particular body orientations. Whether similar separable coding is found in humans is not known, and there is currently no functional account of the visual representation of seen body orientation. This study addressed this issue using visual adaptation. Experiment 1 demonstrated distinct channels that code left- and right-oriented bodies. Experiment 2 investigated whether the visual representation of body orientation is best accounted for by an opponent-coding system, which has been shown to account for the visual representation of facial identity, or by a multichannel system, which provides the optimal account of coding line orientation and direction of motion. Our results provide evidence for multichannel coding of seen body orientation, with separate channels (or neuronal populations) selectively tuned to different body directions.

  14. Probing the functions of contextual modulation by adapting images rather than observers

    PubMed Central

    Webster, Michael A.

    2014-01-01

    Countless visual aftereffects have illustrated how visual sensitivity and perception can be biased by adaptation to the recent temporal context. This contextual modulation has been proposed to serve a variety of functions, but the actual benefits of adaptation remain uncertain. We describe an approach we have recently developed for exploring these benefits by adapting images instead of observers, to simulate how images should appear under theoretically optimal states of adaptation. This allows the long-term consequences of adaptation to be evaluated in ways that are difficult to probe by adapting observers, and provides a common framework for understanding how visual coding changes when the environment or the observer changes, or for evaluating how the effects of temporal context depend on different models of visual coding or the adaptation processes. The approach is illustrated for the specific case of adaptation to color, for which the initial neural coding and adaptation processes are relatively well understood, but can in principle be applied to examine the consequences of adaptation for any stimulus dimension. A simple calibration that adjusts each neuron’s sensitivity according to the stimulus level it is exposed to is sufficient to normalize visual coding and generate a host of benefits, from increased efficiency to perceptual constancy to enhanced discrimination. This temporal normalization may also provide an important precursor for the effective operation of contextual mechanisms operating across space or feature dimensions. To the extent that the effects of adaptation can be predicted, images from new environments could be “pre-adapted” to match them to the observer, eliminating the need for observers to adapt. PMID:25281412

  15. Putting Actions in Context: Visual Action Adaptation Aftereffects Are Modulated by Social Contexts

    PubMed Central

    de la Rosa, Stephan; Streuber, Stephan; Giese, Martin; Bülthoff, Heinrich H.; Curio, Cristóbal

    2014-01-01

    The social context in which an action is embedded provides important information for the interpretation of an action. Is this social context integrated during the visual recognition of an action? We used a behavioural visual adaptation paradigm to address this question and measured participants’ perceptual bias of a test action after they were adapted to one of two adaptors (adaptation after-effect). The action adaptation after-effect was measured for the same set of adaptors in two different social contexts. Our results indicate that the size of the adaptation effect varied with social context (social context modulation) although the physical appearance of the adaptors remained unchanged. Three additional experiments provided evidence that the observed social context modulation of the adaptation effect are owed to the adaptation of visual action recognition processes. We found that adaptation is critical for the social context modulation (experiment 2). Moreover, the effect is not mediated by emotional content of the action alone (experiment 3) and visual information about the action seems to be critical for the emergence of action adaptation effects (experiment 4). Taken together these results suggest that processes underlying visual action recognition are sensitive to the social context of an action. PMID:24466123

  16. The function of stereotypes in visual perception.

    PubMed

    Niemeyer, Greg O

    2003-01-01

    Human vision is a product of both physiological and cultural dispositions. This cultural study investigates the role of cultural dispositions in visual perception. In particular, the study focuses on the role of stereotypes, which are involved in recognition. I propose that stereotypes are essential for basic functions of perception and human perception. However, stereotypes also introduce significant limitations on human experience. The fact that stereotypes are abstract simplifications of realities is not the limiting factor, since scientific and cultural progress continually refines stereotypes. The very principle of the stereotype appears to introduce the limitation, because the process of forming stereotypes requires both temporal and functional fragmentations of the continuum of our perception. This fragmentation can be a cause of sensory overload, a postmodern condition that generates cultural, perceptual and behavioral problems. To address this problem, I propose a cultural modification to our modality of perception. The modification shifts the emphasis of our perception from the recognition of stereotypes to the recognition of flows, processes and durations. References to the work of Henri Bergson and Martin Heidegger provide the philosophical basis for this modification and several empirical and experimental examples illustrate such modifications in practice.

  17. Recreating a functional ancestral archosaur visual pigment.

    PubMed

    Chang, Belinda S W; Jönsson, Karolina; Kazmi, Manija A; Donoghue, Michael J; Sakmar, Thomas P

    2002-09-01

    The ancestors of the archosaurs, a major branch of the diapsid reptiles, originated more than 240 MYA near the dawn of the Triassic Period. We used maximum likelihood phylogenetic ancestral reconstruction methods and explored different models of evolution for inferring the amino acid sequence of a putative ancestral archosaur visual pigment. Three different types of maximum likelihood models were used: nucleotide-based, amino acid-based, and codon-based models. Where possible, within each type of model, likelihood ratio tests were used to determine which model best fit the data. Ancestral reconstructions of the ancestral archosaur node using the best-fitting models of each type were found to be in agreement, except for three amino acid residues at which one reconstruction differed from the other two. To determine if these ancestral pigments would be functionally active, the corresponding genes were chemically synthesized and then expressed in a mammalian cell line in tissue culture. The expressed artificial genes were all found to bind to 11-cis-retinal to yield stable photoactive pigments with lambda(max) values of about 508 nm, which is slightly redshifted relative to that of extant vertebrate pigments. The ancestral archosaur pigments also activated the retinal G protein transducin, as measured in a fluorescence assay. Our results show that ancestral genes from ancient organisms can be reconstructed de novo and tested for function using a combination of phylogenetic and biochemical methods.

  18. Flicker adaptation of low-level cortical visual neurons contributes to temporal dilation

    PubMed Central

    Ortega, Laura; Guzman-Martinez, Emmanuel; Grabowecky, Marcia; Suzuki, Satoru

    2013-01-01

    Several seconds of adaptation to a flickered stimulus causes a subsequent brief static stimulus to appear longer in duration. Non-sensory factors such as increased arousal and attention have been thought to mediate this flicker-based temporal-dilation aftereffect. Here we provide evidence that adaptation of low-level cortical visual neurons contributes to this aftereffect. The aftereffect was significantly reduced by a 45° change in Gabor orientation between adaptation and test. Because orientation-tuning bandwidths are smaller in lower-level cortical visual areas and are approximately 45° in human V1, the result suggests that flicker adaptation of orientation-tuned V1 neurons contributes to the temporal-dilation aftereffect. The aftereffect was abolished when the adaptor and test stimuli were presented to different eyes. Because eye preferences are strong in V1 but diminish in higher-level visual areas, the eye specificity of the aftereffect corroborates the involvement of low-level cortical visual neurons. Our results thus suggest that flicker adaptation of low-level cortical visual neurons contributes to expanding visual duration. Furthermore, this temporal-dilation aftereffect dissociates from the previously reported temporal-constriction aftereffect on the basis of the differences in their orientation and flicker-frequency selectivity, suggesting that the visual system possesses at least two distinct and potentially complementary mechanisms for adaptively coding perceived duration. PMID:22866761

  19. Spatial frequency-specific contrast adaptation originates in the primary visual cortex.

    PubMed

    Duong, Thang; Freeman, Ralph D

    2007-07-01

    Adaptation to a high-contrast grating stimulus causes reduced sensitivity to subsequent presentation of a visual stimulus with similar spatial characteristics. This behavioral finding has been attributed by neurophysiological studies to processes within the visual cortex. However, some evidence indicates that contrast adaptation phenomena are also found in early visual pathways. Adaptation effects have been reported in retina and lateral geniculation nucleus (LGN). It is possible that these early pathways could be the physiological origin of the cortical adaptation effect. To study this, we recorded from single neurons in the cat's LGN. We find that contrast adaptation in the LGN, unlike that in the visual cortex, is not spatial frequency specific, i.e., adaptation effects apply to a broad range of spatial frequencies. In addition, aside from the amplitude attenuation, the shape of spatial frequency tuning curves of LGN cells is not affected by contrast adaptation. Again, these findings are unlike those found for cells in the visual cortex. Together, these results demonstrate that pattern specific contrast adaptation is a cortical process.

  20. Filter goggles imitating dark adaptation for measurement of visual readaptation after flash exposure.

    PubMed

    Wang, L; Zand, M R; Söderberg, P G

    1994-08-01

    The effect of red pass goggles (cut off wavelength = 650 nm) imitating dark adaptation on measurement of visual readaptation after flash exposure was investigated in humans. The results showed that there is no statistically significant difference between visual readaptation time measured with ordinary dark adaptation and that with goggles for adaptation. No statistically significant difference was found between females and males. It is suggested that red pass goggles can be practicably used to simulate dark adaptation in measuring visual readaptation time. Visual readaptation time was measured as the interval between the triggering of a green flash and the reappearance of optokinetic nystagmus. Optokinetic nystagmus was induced by a moving vertical grating and recorded by DC EOG.

  1. [Visual and motor functions in schizophrenic patients].

    PubMed

    Del Vecchio, S; Gargiulo, P A

    1992-12-01

    In the present work, visual and motor functions have been explored in 26 chronic schizophrenic patients, and 7 acute schizophrenic patients, compared with 26 normal controls, by means of the Bender-Gestalt Test. Parameters under consideration were: Form distortion, rotation, integration, perseveration, use of space, subtle motricity, score (global parameter), and time employed. As regards distortion and rotation there have been highly significant differences between chronic patients and control group. Among acute patients, it was observed that perseveration was also highly significant. Conversely, integration and use of space did not differ significantly among the three groups involved. The global score, resulting from all the above mentioned parameters showed important differences between both patient groups on the one hand, and control group on the other hand. Taking into account that patients were being administered neuroleptic drugs, it can safely be said, however, that the Bender-Gestalt Test allows to recognize alteration in perceptual closure consistent with a loss of the objective structure of perceived phenomena, in both chronic and acute patients.

  2. Visual Contrast Sensitivity Functions Obtained from Untrained Observers Using Tracking and Staircase Procedures. Final Report.

    ERIC Educational Resources Information Center

    Geri, George A.; Hubbard, David C.

    Two adaptive psychophysical procedures (tracking and "yes-no" staircase) for obtaining human visual contrast sensitivity functions (CSF) were evaluated. The procedures were chosen based on their proven validity and the desire to evaluate the practical effects of stimulus transients, since tracking procedures traditionally employ gradual…

  3. Rapid adaptation in visual cortex to the structure of images.

    PubMed

    Müller, J R; Metha, A B; Krauskopf, J; Lennie, P

    1999-08-27

    Complex cells in striate cortex of macaque showed a rapid pattern-specific adaptation. Adaptation made cells more sensitive to orientation change near the adapting orientation. It reduced correlations among the responses of populations of cells, thereby increasing the information transmitted by each action potential. These changes were brought about by brief exposures to stationary patterns, on the time scale of a single fixation. Thus, if successive fixations expose neurons' receptive fields to images with similar but not identical structure, adaptation will remove correlations and improve discriminability.

  4. Visual function of children with visual and other disabilities in Oman: A case series

    PubMed Central

    Gogri, Urmi; Khandekar, Rajiv; Al Harby, Salah

    2016-01-01

    Background: We assessed the visual functioning of the children with special needs in Oman between 2009 and 2012. We present the methods of assessing different visual functions, outcomes, and interventions carried out to improve their functioning. Methods: Optometrists assessed visual functions of children of “Day care centres” in Oman. Experts further assessed them and provided low vision care. Ocular movements, refractive corrections, near, distance, contrast color, motion, field of vision, and cognitive visual function test results were noted. Feedback to caregivers was given to improve visual functioning of these children. Results: We grouped 321 participants, (196 [61.1%] boys, age range of 3–18 years) into 61; Down syndrome (DS), 72 with intellectual disabilities (IDs), 67; hearing impaired and 121 with other conditions. Refractive error and lag of accommodation were 26 (42.6%) and 14 (22.6%) among children with DS. Contrast sensitivity was impaired in 8 (12.7%) among hearing impaired children. Defective distant and near vision was in 162 (70%) and 104 (42%) of our cohort. Children with ID were most difficult to assess. Children in a group of other disabilities had a higher proportion of impaired visual functioning. They were given low vision aids (telescopes [22], filters [7], and magnifiers [3]) in large numbers compared to those in other groups. Conclusions: Visual functioning of children with other disabilities show great variation and difficult to group. The care, therefore, should be at individual level. All visual functions cannot be assessed at one time. PMID:28112128

  5. Visual Behaviors and Adaptations Associated with Cortical and Ocular Impairment in Children.

    ERIC Educational Resources Information Center

    Jan, J. E.; Groenveld, M.

    1993-01-01

    This article shows the usefulness of understanding visual behaviors in the diagnosis of various types of visual impairments that are due to ocular and cortical disorders. Behaviors discussed include nystagmus, ocular motor dyspraxia, head position, close viewing, field loss adaptations, mannerisms, photophobia, and abnormal color perception. (JDD)

  6. AccesSports: A Model for Adapting Mainstream Sports Activities for Individuals with Visual Impairments.

    ERIC Educational Resources Information Center

    Ponchilla, Paul E.

    1995-01-01

    The AccesSports Model allows professionals with basic knowledge of visual impairments and mainstream sports to analyze any sports activity and design adaptations needed for targets or goals, boundaries, and rules to enable individuals with visual impairments to participate. Suggestions for modifying baseball, table tennis, swim racing, wrestling,…

  7. Adaptation to chromatic aberration by the human visual system.

    PubMed

    HAY, J C; PICK, H L; ROSSER, E

    1963-07-12

    Prolonged exposure to the chromatic dispersion produced by prism spectacles leads to a perceptual adaptation. The adaptation develops rapidly in the first two days of the wearing of the spectacles, and seems to be a special reac ion to the relative change in illuminance at intensity gradients on the retina.

  8. Adaptive Assessment of Young Children with Visual Impairment

    ERIC Educational Resources Information Center

    Ruiter, Selma; Nakken, Han; Janssen, Marleen; Van Der Meulen, Bieuwe; Looijestijn, Paul

    2011-01-01

    The aim of this study was to assess the effect of adaptations for children with low vision of the Bayley Scales, a standardized developmental instrument widely used to assess development in young children. Low vision adaptations were made to the procedures, item instructions and play material of the Dutch version of the Bayley Scales of Infant…

  9. Visual impairment, visual functioning, and quality of life assessments in patients with glaucoma.

    PubMed Central

    Parrish, R K

    1996-01-01

    BACKGROUND/PURPOSE: To determine the relation between visual impairment, visual functioning, and the global quality of life in patients with glaucoma. METHODS: Visual impairment, defined with the American Medical Association Guides to the Evaluation of Permanent Impairment; visual functioning, measured with the VF-14 and the Field Test Version of the National Eye Institute-Visual Functioning Questionnaire (NEI-VFQ); and the global quality of life, assessed with the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), were determined in 147 consecutive patients with glaucoma. RESULTS: None of the SF-36 domains demonstrated more than a weak correlation with visual impairment. The VF-14 scores were moderately correlated with visual impairment. Of the twelve NEI-VFQ scales, distance activities and vision specific dependency were moderately correlated with visual impairment. Of the twelve NEI-VFQ scales, distance activities and vision specific dependency were moderately correlated with visual field impairment; vision specific social functioning, near activities, vision specific role difficulties, general vision, vision specific mental health, color vision, and driving were modestly correlated; visual pain was weakly correlated; and two were not significantly correlated. Correcting for visual actuity weakened the strength of the correlation coefficients. CONCLUSIONS: The SF-36 is unlikely to be useful in determining visual impairment in patients with glaucoma. Based on the moderate correlation between visual field impairment and the VF-14 score, this questionnaire may be generalizable to patients with glaucoma. Several of the NEI-VFQ scales correlate with visual field impairment scores in patients with a wide range of glaucomatous damage. PMID:8981717

  10. Ecological adaptation determines functional mammalian olfactory subgenomes

    PubMed Central

    Hayden, Sara; Bekaert, Michaël; Crider, Tess A.; Mariani, Stefano; Murphy, William J.; Teeling, Emma C.

    2010-01-01

    The ability to smell is governed by the largest gene family in mammalian genomes, the olfactory receptor (OR) genes. Although these genes are well annotated in the finished human and mouse genomes, we still do not understand which receptors bind specific odorants or how they fully function. Previous comparative studies have been taxonomically limited and mostly focused on the percentage of OR pseudogenes within species. No study has investigated the adaptive changes of functional OR gene families across phylogenetically and ecologically diverse mammals. To determine the extent to which OR gene repertoires have been influenced by habitat, sensory specialization, and other ecological traits, to better understand the functional importance of specific OR gene families and thus the odorants they bind, we compared the functional OR gene repertoires from 50 mammalian genomes. We amplified more than 2000 OR genes in aquatic, semi-aquatic, and flying mammals and coupled these data with 48,000 OR genes from mostly terrestrial mammals, extracted from genomic projects. Phylogenomic, Bayesian assignment, and principle component analyses partitioned species by ecotype (aquatic, semi-aquatic, terrestrial, flying) rather than phylogenetic relatedness, and identified OR families important for each habitat. Functional OR gene repertoires were reduced independently in the multiple origins of aquatic mammals and were significantly divergent in bats. We reject recent neutralist views of olfactory subgenome evolution and correlate specific OR gene families with physiological requirements, a preliminary step toward unraveling the relationship between specific odors and respective OR gene families. PMID:19952139

  11. In vivo cellular visualization of the human retina using optical coherence tomography and adaptive optics

    SciTech Connect

    Olivier, S S; Jones, S M; Chen, D C; Zawadzki, R J; Choi, S S; Laut, S P; Werner, J S

    2006-01-05

    Optical coherence tomography (OCT) sees the human retina sharply with adaptive optics. In vivo cellular visualization of the human retina at micrometer-scale resolution is possible by enhancing Fourier-domain optical-coherence tomography with adaptive optics, which compensate for the eye's optical aberrations.

  12. Evaluation of the visual function of patients with locked-in syndrome: Report of 13 cases.

    PubMed

    Graber, M; Challe, G; Alexandre, M F; Bodaghi, B; LeHoang, P; Touitou, V

    2016-05-01

    Although visual function is thought to be preserved in patients with locked-in syndrome (LIS), enabling them to communicate through vertical or lateral eye movements or blinking of the upper eyelid, nothing is known about the actual visual function of patients with LIS. The goal of this study is to evaluate the visual function of patients with LIS which may enable better evaluation of the state of consciousness of these patients. Patients with LIS seen in a single neurovascular unit of a tertiary center between 1997 and 2013 were retrospectively reviewed. Each patient had a specialized neuro-ophthalmological evaluation under optimal environmental conditions (light, contrast, examination distance, head position, best ergonomic adaptation, and establishment of a means of communication with help from the patient's friends/family). Visual acuity, extraocular eye movements, confrontational visual field, slit lamp and fundus examination were performed. Thirteen patients (6M/7F) were included in this study. Mean visual acuity was 20/60. Oculomotor examination was abnormal in 77%. Forty-six percent of patients presented binocular diplopia mainly related to a VIth nerve palsy. One patient presented complete ophthalmoplegia. Forty-six percent of patients had nystagmus responsible for oscillopsia (oculopalatal tremor). An abnormal visual field was observed in 17% of patients, and abnormal pupillary light response leading to photophobia was present in 22% of patients. Keratitis or dry eye syndrome was present in most patients and was a major cause of pain and visual impairment. Our results suggest that the visual function is impaired in all patients with LIS. This impairment is multifactorial including mostly binocular diplopia or oscillopsia but also refractive errors, dry eye syndrome, keratitis or visual field defect. This altered visual function may alter the ability of the patient to interact with his environment and lead to underestimation of their state of consciousness

  13. Visual Impairments in People with Severe and Profound Multiple Disabilities: An Inventory of Visual Functioning

    ERIC Educational Resources Information Center

    van den Broek, Ellen G. C.; Janssen, C. G. C.; van Ramshorst, T.; Deen, L.

    2006-01-01

    Background: The prevalence of visual impairments in people with severe and profound multiple disabilities (SPMD) is the subject of considerable debate and is difficult to assess. Methods: In a typical Dutch care organization, all clients with SPMD (n = 76) participated in the study and specific instruments adapted to these clients (requiring a…

  14. Adaptive Kalman filtering for real-time mapping of the visual field.

    PubMed

    Ward, B Douglas; Janik, John; Mazaheri, Yousef; Ma, Yan; DeYoe, Edgar A

    2012-02-15

    This paper demonstrates the feasibility of real-time mapping of the visual field for clinical applications. Specifically, three aspects of this problem were considered: (1) experimental design, (2) statistical analysis, and (3) display of results. Proper experimental design is essential to achieving a successful outcome, particularly for real-time applications. A random-block experimental design was shown to have less sensitivity to measurement noise, as well as greater robustness to error in modeling of the hemodynamic impulse response function (IRF) and greater flexibility than common alternatives. In addition, random encoding of the visual field allows for the detection of voxels that are responsive to multiple, not necessarily contiguous, regions of the visual field. Due to its recursive nature, the Kalman filter is ideally suited for real-time statistical analysis of visual field mapping data. An important feature of the Kalman filter is that it can be used for nonstationary time series analysis. The capability of the Kalman filter to adapt, in real time, to abrupt changes in the baseline arising from subject motion inside the scanner and other external system disturbances is important for the success of clinical applications. The clinician needs real-time information to evaluate the success or failure of the imaging run and to decide whether to extend, modify, or terminate the run. Accordingly, the analytical software provides real-time displays of (1) brain activation maps for each stimulus segment, (2) voxel-wise spatial tuning profiles, (3) time plots of the variability of response parameters, and (4) time plots of activated volume.

  15. Longitudinal Trajectories of Intellectual and Adaptive Functioning in Adolescents and Adults with Williams Syndrome

    ERIC Educational Resources Information Center

    Fisher, M. H.; Lense, M. D.; Dykens, E. M.

    2016-01-01

    Background: Williams syndrome (WS) is associated with a distinct cognitive-behavioural phenotype including mild to moderate intellectual disability, visual-spatial deficits, hypersociability, inattention and anxiety. Researchers typically characterise samples of individuals with WS by their intellectual functioning and adaptive behaviour. Because…

  16. An insect-inspired model for visual binding II: functional analysis and visual attention.

    PubMed

    Northcutt, Brandon D; Higgins, Charles M

    2017-04-01

    We have developed a neural network model capable of performing visual binding inspired by neuronal circuitry in the optic glomeruli of flies: a brain area that lies just downstream of the optic lobes where early visual processing is performed. This visual binding model is able to detect objects in dynamic image sequences and bind together their respective characteristic visual features-such as color, motion, and orientation-by taking advantage of their common temporal fluctuations. Visual binding is represented in the form of an inhibitory weight matrix which learns over time which features originate from a given visual object. In the present work, we show that information represented implicitly in this weight matrix can be used to explicitly count the number of objects present in the visual image, to enumerate their specific visual characteristics, and even to create an enhanced image in which one particular object is emphasized over others, thus implementing a simple form of visual attention. Further, we present a detailed analysis which reveals the function and theoretical limitations of the visual binding network and in this context describe a novel network learning rule which is optimized for visual binding.

  17. Visual Afterimages of Emotional Faces in High Functioning Autism

    ERIC Educational Resources Information Center

    Rutherford, M. D.; Troubridge, Erin K.; Walsh, Jennifer

    2012-01-01

    Fixating an emotional facial expression can create afterimages, such that subsequent faces are seen as having the opposite expression of that fixated. Visual afterimages have been used to map the relationships among emotion categories, and this method was used here to compare ASD and matched control participants. Participants adapted to a facial…

  18. Effects of Colored Filters on Visual Function

    DTIC Science & Technology

    2008-05-01

    normal vision, yellow filters have been reported to reduce glare and improve overall visual performance.4-9 The claims of improved vision in dyslexia ...use of tinted lenses and colored overlays for the treatment of dyslexia and other related reading and learning disorders. American Optometric

  19. Evaluation of stereoscopic display with visual function and interview

    NASA Astrophysics Data System (ADS)

    Okuyama, Fumio

    1999-05-01

    The influence of binocular stereoscopic (3D) television display on the human eye were compared with one of a 2D display, using human visual function testing and interviews. A 40- inch double lenticular display was used for 2D/3D comparison experiments. Subjects observed the display for 30 minutes at a distance 1.0 m, with a combination of 2D material and one of 3D material. The participants were twelve young adults. Main optometric test with visual function measured were visual acuity, refraction, phoria, near vision point, accommodation etc. The interview consisted of 17 questions. Testing procedures were performed just before watching, just after watching, and forty-five minutes after watching. Changes in visual function are characterized as prolongation of near vision point, decrease of accommodation and increase in phoria. 3D viewing interview results show much more visual fatigue in comparison with 2D results. The conclusions are: 1) change in visual function is larger and visual fatigue is more intense when viewing 3D images. 2) The evaluation method with visual function and interview proved to be very satisfactory for analyzing the influence of stereoscopic display on human eye.

  20. Functional organization of telencephalic visual association fields in pigeons.

    PubMed

    Stacho, Martin; Ströckens, Felix; Xiao, Qian; Güntürkün, Onur

    2016-04-15

    Birds show remarkable visual abilities that surpass most of our visual psychophysiological abilities. In this study, we investigated visual associative areas of the tectofugal visual system in pigeons. Similar to the condition in mammals, ascending visual pathways in birds are subdivided into parallel form/color vs. motion streams at the thalamic and primary telencephalic level. However, we know practically nothing about the functional organization of those telencephalic areas that receive input from the primary visual telencephalic fields. The current study therefore had two objectives: first, to reveal whether these visual associative areas of the tectofugal system are activated during visual discrimination tasks; second, to test whether separated form/color vs. motion pathways can be discerned among these association fields. To this end, we trained pigeons to discriminate either form/color or motion stimuli and used the immediate early gene protein ZENK to capture the activity of the visual associative areas during the task. We could indeed identify several visual associative telencephalic structures by activity pattern changes during discriminations. However, none of these areas displayed a difference between form/color vs. motion sessions. The presence of such a distinction in thalamo-telencephalic, but not in further downstream visual association areas opens the possibility that these separate streams converge very early in birds, which possibly minimizes long-range connections due to the evolutionary pressure toward miniaturized brains.

  1. Adaptability of expert visual anticipation in baseball batting.

    PubMed

    Müller, Sean; Fadde, Peter J; Harbaugh, Allen G

    2016-09-09

    By manipulating stimulus variation in terms of opponent pitcher actions, this study investigated the capability of expert (n = 30) and near-expert (n = 95) professional baseball batters to adapt anticipation skill when using the video simulation temporal occlusion paradigm. Participants watched in-game footage of two pitchers, one after the other, that was temporally occluded at ball release and various points during ball flight. They were required to make a written prediction of pitch types and locations. Per cent accuracy was calculated for pitch type, for pitch location, and for type and location combined. Results indicated that experts and near-experts could adapt their anticipation to predict above guessing level across both pitchers, but adaptation to the left-handed pitcher was poorer than the right-handed pitcher. Small-to-moderate effect sizes were found in terms of superior adaptation by experts over near-experts at the ball release and early ball flight occlusion conditions. The findings of this study extend theoretical and applied knowledge of expertise in striking sports. Practical application of the instruments and findings are discussed in terms of applied researchers, practitioners and high-performance staff in professional sporting organisations.

  2. Visual function of children with visual and other disabilities in Oman: A case series

    PubMed Central

    Gogri, Urmi; Al Harby, Salah; Khandekar, Rajiv

    2015-01-01

    Background: We assessed visual functioning of the children with special needs in Oman between 2009 and 2012. We present the methods of assessing different visual functions, outcomes and interventions carried out to improve their functioning. Materials and Methods: In this case series type of study, optometrists assessed visual functions of children of “day care centers” in Oman. Experts further assessed them and provided low vision care. Ocular movements, refractive corrections, near, distance, contrast color, motion, field of vision and cognitive, visual function test results were noted. Feedback to caregivers was given to improving visual functioning of these children. Results: We grouped 321 participants, (196 (61.1%) boys, age range of 3-18 years) into 61; Down syndrome (DS), 72 with intellectual disabilities, 67; hearing impaired and 121 with other conditions. Refractive error and lag of accommodation was 26 (42.6%) and 14 (22.6%) among children with DS. Contrast sensitivity was impaired in 8 (12.7%) among hearing impaired children. Defective distant and near vision was in 162 (70%) and 104 (42%) of our cohort. Children with intellectual disability were most difficult to assess. Children in group of other disabilities” had a higher proportion of impaired visual functioning. They were given low vision aids (telescopes (22), filters (7) and magnifiers (3)) in large numbers compared to those in other groups. Conclusions: The outcomes of assessment of visual functioning of children with other disabilities show great variation and difficult to group. The care therefore should be individual. All visual functions cannot be assessed at one time. PMID:26622136

  3. Structural and functional changes across the visual cortex of a patient with visual form agnosia.

    PubMed

    Bridge, Holly; Thomas, Owen M; Minini, Loredana; Cavina-Pratesi, Cristiana; Milner, A David; Parker, Andrew J

    2013-07-31

    Loss of shape recognition in visual-form agnosia occurs without equivalent losses in the use of vision to guide actions, providing support for the hypothesis of two visual systems (for "perception" and "action"). The human individual DF received a toxic exposure to carbon monoxide some years ago, which resulted in a persisting visual-form agnosia that has been extensively characterized at the behavioral level. We conducted a detailed high-resolution MRI study of DF's cortex, combining structural and functional measurements. We present the first accurate quantification of the changes in thickness across DF's occipital cortex, finding the most substantial loss in the lateral occipital cortex (LOC). There are reduced white matter connections between LOC and other areas. Functional measures show pockets of activity that survive within structurally damaged areas. The topographic mapping of visual areas showed that ordered retinotopic maps were evident for DF in the ventral portions of visual cortical areas V1, V2, V3, and hV4. Although V1 shows evidence of topographic order in its dorsal portion, such maps could not be found in the dorsal parts of V2 and V3. We conclude that it is not possible to understand fully the deficits in object perception in visual-form agnosia without the exploitation of both structural and functional measurements. Our results also highlight for DF the cortical routes through which visual information is able to pass to support her well-documented abilities to use visual information to guide actions.

  4. Robust visual tracking via adaptive kernelized correlation filter

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Wang, Desheng; Liao, Qingmin

    2016-10-01

    Correlation filter based trackers have proved to be very efficient and robust in object tracking with a notable performance competitive with state-of-art trackers. In this paper, we propose a novel object tracking method named Adaptive Kernelized Correlation Filter (AKCF) via incorporating Kernelized Correlation Filter (KCF) with Structured Output Support Vector Machines (SOSVM) learning method in a collaborative and adaptive way, which can effectively handle severe object appearance changes with low computational cost. AKCF works by dynamically adjusting the learning rate of KCF and reversely verifies the intermediate tracking result by adopting online SOSVM classifier. Meanwhile, we bring Color Names in this formulation to effectively boost the performance owing to its rich feature information encoded. Experimental results on several challenging benchmark datasets reveal that our approach outperforms numerous state-of-art trackers.

  5. Visual alchemy: stereoscopic adaptation produces kinetic depth from random noise.

    PubMed

    Nawrot, M; Blake, R

    1993-01-01

    Observers perceive incoherent motion and no hint of depth when viewing stochastic motion, in which stimulus elements move in all possible directions. As earlier work has shown, depth can be specified by introducing a brief interocular delay between the presentation of corresponding animation frames of this 'noise' to the left and right eyes. A study is reported in which observers were adapted to a stereoscopic display consisting of coherent planes of motion at different depths. This stereoscopic adaptation caused incoherent depthless motion to take on the qualities of structure and depth, and it could nullify the depth induced by interocular delay. The findings are interpreted within the context of a neural model consisting of units selectively responsive to different directions of motion at different planes of depth.

  6. Visually induced adaptation in three-dimensional organization of primate vestibuloocular reflex

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1998-01-01

    The adaptive plasticity of the spatial organization of the vestibuloocular reflex (VOR) has been investigated in intact and canal-plugged primates using 2-h exposure to conflicting visual (optokinetic, OKN) and vestibular rotational stimuli about mutually orthogonal axes (generating torsional VOR + vertical OKN, torsional VOR + horizontal OKN, vertical VOR + horizontal OKN, and horizontal VOR + vertical OKN). Adaptation protocols with 0.5-Hz (+/-18 degrees ) head movements about either an earth-vertical or an earth-horizontal axis induced orthogonal response components as high as 40-70% of those required for ideal adaptation. Orthogonal response gains were highest at the adapting frequency with phase leads present at lower and phase lags present at higher frequencies. Furthermore, the time course of adaptation, as well as orthogonal response dynamics were similar and relatively independent of the particular visual/vestibular stimulus combination. Low-frequency (0. 05 Hz, vestibular stimulus: +/-60 degrees ; optokinetic stimulus: +/-180 degrees ) adaptation protocols with head movements about an earth-vertical axis induced smaller orthogonal response components that did not exceed 20-40% of the head velocity stimulus (i.e., approximately 10% of that required for ideal adaptation). At the same frequency, adaptation with head movements about an earth-horizontal axis generated large orthogonal responses that reached values as high as 100-120% of head velocity after 2 h of adaptation (i.e., approximately 40% of ideal adaptation gains). The particular spatial and temporal response characteristics after low-frequency, earth-horizontal axis adaptation in both intact and canal-plugged animals strongly suggests that the orienting (and perhaps translational) but not inertial (velocity storage) components of the primate otolith-ocular system exhibit spatial adaptability. Due to the particular nested arrangement of the visual and vestibular stimuli, the optic flow pattern

  7. The locus of flicker adaptation in the migraine visual system: A dichoptic study

    PubMed Central

    Thabet, Michel; Wilkinson, Frances; Wilson, Hugh R.; Karanovic, Olivera

    2014-01-01

    Background Flickering light has been shown to sensitize the migraine visual system at high stimulus contrast while elevating thresholds at low contrast. The present study employs a dichoptic psychophysical paradigm to ask whether the abnormal adaptation to flicker in migraine occurs before or after the binocular combination of inputs from the two eyes in the visual cortex. Methods Following adaptation to high contrast flicker presented to one eye only, flicker contrast increment thresholds were measured in each eye separately using dichoptic viewing. Results Modest inter-ocular transfer of adaptation was seen in both migraine and control groups at low contrast. Sensitization at high contrast in migraine relative to control participants was seen in the adapted eye only, and an unanticipated threshold elevation occurred in the non-adapted eye. Migraineurs also showed significantly lower aversion thresholds to full field flicker than control participants, but aversion scores and increment thresholds were not correlated. Conclusions The results are simulated with a three-stage neural model of adaptation that points to strong adaptation at monocular sites prior to binocular combination, and weaker adaptation at the level of cortical binocular neurons. The sensitization at high contrast in migraine is proposed to result from stronger adaptation of inhibitory neurons, which act as a monocular normalization pool. PMID:23147164

  8. Remaining Visual Field and Preserved Subjective Visual Functioning Prevent Mental Distress in Patients with Visual Field Defects

    PubMed Central

    Gall, Carolin; Brösel, Doreen; Sabel, Bernhard A.

    2013-01-01

    Background: Patients with visual field defects after visual pathway lesion may experience reduced vision-related quality of life (vrQoL). It has not been clarified how vrQoL impairments contribute to vision-related mental distress. Methods: One hundred and eight subjects with visual field defects caused by optic neuropathies (age M = 57.6; SD = 13.7 years) answered the National Eye Institute Visual-Functioning Questionnaire 39 (NEI-VFQ) for vrQoL and the SF-12 Short Form Health Survey for health-related quality of life. A 10 item composite of NEI-VFQ “visual functioning” and 5 items of “mental-health symptoms due to vision problems” were subjected to Rasch analysis. The test battery comprised static and High Resolution Perimetry (HRP). Regression and path analysis were used to investigate associations between QoL, mental distress, and perimetry results. Results: A higher level of “visual functioning” was associated with monocular impairment and a larger remaining visual field compared to binocular impairment. Subjective “visual functioning” but not visual field parameters predicted “mental-health symptoms due to vision problems” which was the only variable associated with the SF-12 mental component score. The SF-12 physical component score was less strongly associated with “mental-health symptoms due to vision problems.” Here, reaction time in HRP and mean threshold in perimetry were additional significant variables. Path analysis revealed a significant path from remaining visual field via visual functioning on mental health. Conclusion: Subjective consequences of visual impairments in everyday life impact mental health rather than “objective” visual function loss as measured by perimetry. Since a higher extent of vrQoL was related to lower levels of mental distress, the maintenance of vrQoL could reduce and prevent mental distress due to vision problems. Patients with persisting visual field defects may benefit from

  9. Complex Visual Adaptations in Squid for Specific Tasks in Different Environments

    PubMed Central

    Chung, Wen-Sung; Marshall, N. Justin

    2017-01-01

    In common with their major competitors, the fish, squid are fast moving visual predators that live over a great range of depths in the ocean. Both squid and fish show a variety of adaptations with respect to optical properties, receptors and their underlying neural circuits, and these adaptations are often linked to the light conditions of their specific niche. In contrast to the extensive investigations of adaptive strategies in fish, vision in response to the varying quantity and quality of available light, our knowledge of visual adaptations in squid remains sparse. This study therefore undertook a comparative study of visual adaptations and capabilities in a number of squid species collected between 0 and 1,200 m. Histology, magnetic resonance imagery (MRI), and depth distributions were used to compare brains, eyes, and visual capabilities, revealing that the squid eye designs reflect the lifestyle and the versatility of neural architecture in its visual system. Tubular eyes and two types of regional retinal deformation were identified and these eye modifications are strongly associated with specific directional visual tasks. In addition, a combination of conventional and immuno-histology demonstrated a new form of a complex retina possessing two inner segment layers in two mid-water squid species which they rhythmically move across a broad range of depths (50–1,000 m). In contrast to their relatives with the regular single-layered inner segment retina live in the upper mesopelagic layer (50–400 m), the new form of retinal interneuronal layers suggests that the visual sensitivity of these two long distance vertical migrants may increase in response to dimmer environments. PMID:28286484

  10. Effect of visual perception, visual function, cognition, and personality on power wheelchair use in adults.

    PubMed

    Massengale, Samantha; Folden, Donna; McConnell, Pima; Stratton, Laurie; Whitehead, Victoria

    2005-01-01

    The purpose of this study was to determine to what extent visual perception, visual function, cognition, and personality traits affect power wheelchair use in adults. It also proposes to establish baseline information to help clinicians determine or predict power wheelchair driving performance and to develop service plans to address those driving skills that need improvement or compensation. Sixty-two adult power wheelchair users were recruited. Standardized instruments were used to evaluate visual perceptual skills, visual function, cognitive skills, and personality traits. The results of these evaluations were then correlated with participants' scores on a power wheelchair performance test. Strong correlations were found between power wheelchair driving performance and visual perception (p = .000), ocular motor function (p = .000 and p < or = .001), stereodepth perception (p < or = .001), and alertness to the environment (p < or = .001). No significant correlations were found between personality traits and power wheelchair driving performance. These results indicate that good visual perceptual skills, visual function, and various aspects of cognition are necessary for proficient power wheelchair use. These data will assist clinicians in identifying significant factors to consider when evaluating and training clients for power wheelchair use.

  11. Development of Efficiency in Visual Functioning: An Evaluation Process.

    ERIC Educational Resources Information Center

    Collins, Marcia E.; Barraga, Natalie C.

    1980-01-01

    The article reviews the Diagnostic Assessment Procedure and related facets of the evaluation process within the Program to Develop Efficiency in Visual Functioning. Basic assumptions, rationale for development, administration, interpretation, and use of the program are considered. (Author/PHR)

  12. Binocular summation and visual function with induced anisocoria and monovision

    PubMed Central

    Castro, José J.; Soler, Margarita; Ortiz, Carolina; Jiménez, José R.; Anera, Rosario G.

    2016-01-01

    The advances in new techniques for correcting presbyopia, such as a small aperture combined with monovision, require an in-depth study of binocular aspects. In this work, we have studied binocular visual performance of 12 subjects after inducing different degrees of anisocoria combined with two different add powers in the non-dominant eye. We have analysed visual performance in terms of the visual-discrimination capacity (a function to evaluate the strength of bothersome halos) and the contrast-sensitivity. The results show a deterioration of the binocular vision when inducing anisocoria and with any add power, with a higher perception of halos, a lower contrast sensitivity and poorer binocular summation of these visual functions on increasing anisocoria. This deterioration is clinically acceptable in the case of low add power, since positive binocular summation is maintained in contrast sensitivity, and visual discrimination is not altered. PMID:27867729

  13. Yoga-teaching protocol adapted for children with visual impairment

    PubMed Central

    Mohanty, Soubhagyalaxmi; Hankey, Alex; Pradhan, Balaram; Ranjita, Rajashree

    2016-01-01

    Context: Childhood visual deficiency impairs children's neuro-psychomotor development, considerably affecting physical, mental, social, and emotional health. Yoga's multifaceted approach may help children with visual impairment (VI) to cope with their challenges. Aim: This study aimed to develop a special protocol for teaching yoga to children with VI, and to evaluate their preferred method of learning. Methods: The study was carried out at Ramana Maharishi Academy for the Blind, Bengaluru, South India. Forty-one students volunteered to learn yoga practices, and classes were held weekly 5 days, 1 hr per session for 16 weeks. The study introduced a new method using a sequence of five teaching steps: verbal instructions, tactile modeling, step-by-step teaching, learning in a group, and physical guidance. A questionnaire concerning the preferred steps of learning was then given to each student, and verbal answers were obtained. Results: A total of 33 (out of 41), aged 11.97 ± 1.94, 15 girls and 18 boys responded. Twenty-six (78.79%) chose physical guidance as their most favored learning mode. Conclusions: Specially designed protocol may pave the way to impart yoga in an exciting and comfortable way to children with VI. More studies are needed to further investigate the effectiveness of this new yoga protocol in similar settings. PMID:27512318

  14. An Efficient Adaptive Window Size Selection Method for Improving Spectrogram Visualization

    PubMed Central

    Khan, Omar Usman

    2016-01-01

    Short Time Fourier Transform (STFT) is an important technique for the time-frequency analysis of a time varying signal. The basic approach behind it involves the application of a Fast Fourier Transform (FFT) to a signal multiplied with an appropriate window function with fixed resolution. The selection of an appropriate window size is difficult when no background information about the input signal is known. In this paper, a novel empirical model is proposed that adaptively adjusts the window size for a narrow band-signal using spectrum sensing technique. For wide-band signals, where a fixed time-frequency resolution is undesirable, the approach adapts the constant Q transform (CQT). Unlike the STFT, the CQT provides a varying time-frequency resolution. This results in a high spectral resolution at low frequencies and high temporal resolution at high frequencies. In this paper, a simple but effective switching framework is provided between both STFT and CQT. The proposed method also allows for the dynamic construction of a filter bank according to user-defined parameters. This helps in reducing redundant entries in the filter bank. Results obtained from the proposed method not only improve the spectrogram visualization but also reduce the computation cost and achieves 87.71% of the appropriate window length selection. PMID:27642291

  15. An Efficient Adaptive Window Size Selection Method for Improving Spectrogram Visualization.

    PubMed

    Nisar, Shibli; Khan, Omar Usman; Tariq, Muhammad

    2016-01-01

    Short Time Fourier Transform (STFT) is an important technique for the time-frequency analysis of a time varying signal. The basic approach behind it involves the application of a Fast Fourier Transform (FFT) to a signal multiplied with an appropriate window function with fixed resolution. The selection of an appropriate window size is difficult when no background information about the input signal is known. In this paper, a novel empirical model is proposed that adaptively adjusts the window size for a narrow band-signal using spectrum sensing technique. For wide-band signals, where a fixed time-frequency resolution is undesirable, the approach adapts the constant Q transform (CQT). Unlike the STFT, the CQT provides a varying time-frequency resolution. This results in a high spectral resolution at low frequencies and high temporal resolution at high frequencies. In this paper, a simple but effective switching framework is provided between both STFT and CQT. The proposed method also allows for the dynamic construction of a filter bank according to user-defined parameters. This helps in reducing redundant entries in the filter bank. Results obtained from the proposed method not only improve the spectrogram visualization but also reduce the computation cost and achieves 87.71% of the appropriate window length selection.

  16. Visual Function and Cortical Organization in Carriers of Blue Cone Monochromacy

    PubMed Central

    Rossi, Ethan A.; Achtman, Rebecca L.; Guidon, Arnaud; Williams, David R.; Roorda, Austin; Bavelier, Daphne; Carroll, Joseph

    2013-01-01

    Carriers of blue cone monochromacy have fewer cone photoreceptors than normal. Here we examine how this disruption at the level of the retina affects visual function and cortical organization in these individuals. Visual resolution and contrast sensitivity was measured at the preferred retinal locus of fixation and visual resolution was tested at two eccentric locations (2.5° and 8°) with spectacle correction only. Adaptive optics corrected resolution acuity and cone spacing were simultaneously measured at several locations within the central fovea with adaptive optics scanning laser ophthalmoscopy (AOSLO). Fixation stability was assessed by extracting eye motion data from AOSLO videos. Retinotopic mapping using fMRI was carried out to estimate the area of early cortical regions, including that of the foveal confluence. Without adaptive optics correction, BCM carriers appeared to have normal visual function, with normal contrast sensitivity and visual resolution, but with AO-correction, visual resolution was significantly worse than normal. This resolution deficit is not explained by cone loss alone and is suggestive of an associated loss of retinal ganglion cells. However, despite evidence suggesting a reduction in the number of retinal ganglion cells, retinotopic mapping showed no reduction in the cortical area of the foveal confluence. These results suggest that ganglion cell density may not govern the foveal overrepresentation in the cortex. We propose that it is not the number of afferents, but rather the content of the information relayed to the cortex from the retina across the visual field that governs cortical magnification, as under normal viewing conditions this information is similar in both BCM carriers and normal controls. PMID:23469117

  17. Visual function and cortical organization in carriers of blue cone monochromacy.

    PubMed

    Rossi, Ethan A; Achtman, Rebecca L; Guidon, Arnaud; Williams, David R; Roorda, Austin; Bavelier, Daphne; Carroll, Joseph

    2013-01-01

    Carriers of blue cone monochromacy have fewer cone photoreceptors than normal. Here we examine how this disruption at the level of the retina affects visual function and cortical organization in these individuals. Visual resolution and contrast sensitivity was measured at the preferred retinal locus of fixation and visual resolution was tested at two eccentric locations (2.5° and 8°) with spectacle correction only. Adaptive optics corrected resolution acuity and cone spacing were simultaneously measured at several locations within the central fovea with adaptive optics scanning laser ophthalmoscopy (AOSLO). Fixation stability was assessed by extracting eye motion data from AOSLO videos. Retinotopic mapping using fMRI was carried out to estimate the area of early cortical regions, including that of the foveal confluence. Without adaptive optics correction, BCM carriers appeared to have normal visual function, with normal contrast sensitivity and visual resolution, but with AO-correction, visual resolution was significantly worse than normal. This resolution deficit is not explained by cone loss alone and is suggestive of an associated loss of retinal ganglion cells. However, despite evidence suggesting a reduction in the number of retinal ganglion cells, retinotopic mapping showed no reduction in the cortical area of the foveal confluence. These results suggest that ganglion cell density may not govern the foveal overrepresentation in the cortex. We propose that it is not the number of afferents, but rather the content of the information relayed to the cortex from the retina across the visual field that governs cortical magnification, as under normal viewing conditions this information is similar in both BCM carriers and normal controls.

  18. Enhancement Of Visual Evoked Potentials By Adaptive Processing

    NASA Astrophysics Data System (ADS)

    Wolf, W.; Appel, U.; Rauner, H.

    1982-11-01

    Transient evoked potentials (EP) are variations of the on-going electroencephalogram (EEG) in response to the application of sensory stimuli. Since their amplitudes are very small in comparison to the spontaneous EEG, signal extraction methods must be applied to them before their characteristics are measureable. Several signal ex-traction methods which are actually used in EP research are outlined, especially those showing an adaptive characteristic. As a further development, a new method is proposed which considers the on-going EEG preceding the stimulus application for the EP processing. The computational procedure will be described and some preliminary results are given.

  19. AVES: an adaptive optics visual echelle spectrograph for the VLT

    NASA Astrophysics Data System (ADS)

    Pasquini, Luca; Delabre, Bernard; Avila, Gerardo; Bonaccini, Domenico

    1998-07-01

    We present the preliminary study of a low cost, high performance spectrograph for the VLT, for observations in the V, R and I bands. This spectrograph is meant for intermediate (R equals 16,000) resolution spectroscopy of faint (sky and/or detector limited) sources, with particular emphasis on the study of solar-type (F-G) stars belonging to the nearest galaxies and to distant (or highly reddened) galactic clusters. The spectrograph is designed to use the adaptive optics (AO) systems at the VLT Telescope. Even if these AO systems will not provide diffraction limited images in the V, R and I bands, the photon concentration will still be above approximately 60% of the flux in an 0.3 arcsecond aperture for typical Paranal conditions. This makes the construction of a compact, cheap and efficient echelle spectrograph possible. AVES will outperform comparable non adaptive optic instruments by more than one magnitude for sky- and/or detector-limited observations, and it will be very suitable for observations in crowded fields.

  20. Data management based on geocoding index and adaptive visualization for airborne LiDAR

    NASA Astrophysics Data System (ADS)

    Zhi, Xiaodong

    2008-10-01

    With more surveying practice and deeper application, data post-process for airborne LiDAR system has been extracted lots of attention in data accuracy, post-process, fusion, modeling, automation and visualization. However, post-process and flexible visualization were found to be the bottle-neck which limits the LiDAR data usage for industrial applications. The cause of above bottle-neck problems is great capacity for LiDAR system. Thus in article a geocoding index based multivariate data management and adaptive visualization will be studied for based on the feature of airborne LiDAR's data to improve automatization of post-process and surveying efficiency.

  1. Predictability is necessary for closed-loop visual feedback delay adaptation.

    PubMed

    Rohde, Marieke; van Dam, Loes C J; Ernst, Marc O

    2014-03-05

    In case of delayed visual feedback during visuomotor tasks, like in some sluggish computer games, humans can modulate their behavior to compensate for the delay. However, opinions on the nature of this compensation diverge. Some studies suggest that humans adapt to feedback delays with lasting changes in motor behavior (aftereffects) and a recalibration of time perception. Other studies have shown little or no evidence for such semipermanent recalibration in the temporal domain. We hypothesize that predictability of the reference signal (target to be tracked) is necessary for semipermanent delay adaptation. To test this hypothesis, we trained participants with a 200 ms visual feedback delay in a visually guided manual tracking task, varying the predictability of the reference signal between conditions, but keeping reference motion and feedback delay constant. In Experiment 1, we focused on motor behavior. Only training in the predictable condition brings about all of the adaptive changes and aftereffects expected from delay adaptation. In Experiment 2, we used a synchronization task to investigate perceived simultaneity (perceptuomotor learning). Supporting the hypothesis, participants recalibrated subjective visuomotor simultaneity only when trained in the predictable condition. Such a shift in perceived simultaneity was also observed in Experiment 3, using an interval estimation task. These results show that delay adaptation in motor control can modulate the perceived temporal alignment of vision and kinesthetically sensed movement. The coadaptation of motor prediction and target prediction (reference extrapolation) seems necessary for such genuine delay adaptation. This offers an explanation for divergent results in the literature.

  2. Tailoring the visual communication of climate projections for local adaptation practitioners in Germany and the UK

    PubMed Central

    Lorenz, Susanne; Dessai, Suraje; Forster, Piers M.; Paavola, Jouni

    2015-01-01

    Visualizations are widely used in the communication of climate projections. However, their effectiveness has rarely been assessed among their target audience. Given recent calls to increase the usability of climate information through the tailoring of climate projections, it is imperative to assess the effectiveness of different visualizations. This paper explores the complexities of tailoring through an online survey conducted with 162 local adaptation practitioners in Germany and the UK. The survey examined respondents’ assessed and perceived comprehension (PC) of visual representations of climate projections as well as preferences for using different visualizations in communicating and planning for a changing climate. Comprehension and use are tested using four different graph formats, which are split into two pairs. Within each pair the information content is the same but is visualized differently. We show that even within a fairly homogeneous user group, such as local adaptation practitioners, there are clear differences in respondents’ comprehension of and preference for visualizations. We do not find a consistent association between assessed comprehension and PC or use within the two pairs of visualizations that we analysed. There is, however, a clear link between PC and use of graph format. This suggests that respondents use what they think they understand the best, rather than what they actually understand the best. These findings highlight that audience-specific targeted communication may be more complex and challenging than previously recognized. PMID:26460109

  3. Tailoring the visual communication of climate projections for local adaptation practitioners in Germany and the UK.

    PubMed

    Lorenz, Susanne; Dessai, Suraje; Forster, Piers M; Paavola, Jouni

    2015-11-28

    Visualizations are widely used in the communication of climate projections. However, their effectiveness has rarely been assessed among their target audience. Given recent calls to increase the usability of climate information through the tailoring of climate projections, it is imperative to assess the effectiveness of different visualizations. This paper explores the complexities of tailoring through an online survey conducted with 162 local adaptation practitioners in Germany and the UK. The survey examined respondents' assessed and perceived comprehension (PC) of visual representations of climate projections as well as preferences for using different visualizations in communicating and planning for a changing climate. Comprehension and use are tested using four different graph formats, which are split into two pairs. Within each pair the information content is the same but is visualized differently. We show that even within a fairly homogeneous user group, such as local adaptation practitioners, there are clear differences in respondents' comprehension of and preference for visualizations. We do not find a consistent association between assessed comprehension and PC or use within the two pairs of visualizations that we analysed. There is, however, a clear link between PC and use of graph format. This suggests that respondents use what they think they understand the best, rather than what they actually understand the best. These findings highlight that audience-specific targeted communication may be more complex and challenging than previously recognized.

  4. Klinefelter syndrome has increased brain responses to auditory stimuli and motor output, but not to visual stimuli or Stroop adaptation.

    PubMed

    Wallentin, Mikkel; Skakkebæk, Anne; Bojesen, Anders; Fedder, Jens; Laurberg, Peter; Østergaard, John R; Hertz, Jens Michael; Pedersen, Anders Degn; Gravholt, Claus Højbjerg

    2016-01-01

    Klinefelter syndrome (47, XXY) (KS) is a genetic syndrome characterized by the presence of an extra X chromosome and low level of testosterone, resulting in a number of neurocognitive abnormalities, yet little is known about brain function. This study investigated the fMRI-BOLD response from KS relative to a group of Controls to basic motor, perceptual, executive and adaptation tasks. Participants (N: KS = 49; Controls = 49) responded to whether the words "GREEN" or "RED" were displayed in green or red (incongruent versus congruent colors). One of the colors was presented three times as often as the other, making it possible to study both congruency and adaptation effects independently. Auditory stimuli saying "GREEN" or "RED" had the same distribution, making it possible to study effects of perceptual modality as well as Frequency effects across modalities. We found that KS had an increased response to motor output in primary motor cortex and an increased response to auditory stimuli in auditory cortices, but no difference in primary visual cortices. KS displayed a diminished response to written visual stimuli in secondary visual regions near the Visual Word Form Area, consistent with the widespread dyslexia in the group. No neural differences were found in inhibitory control (Stroop) or in adaptation to differences in stimulus frequencies. Across groups we found a strong positive correlation between age and BOLD response in the brain's motor network with no difference between groups. No effects of testosterone level or brain volume were found. In sum, the present findings suggest that auditory and motor systems in KS are selectively affected, perhaps as a compensatory strategy, and that this is not a systemic effect as it is not seen in the visual system.

  5. Klinefelter syndrome has increased brain responses to auditory stimuli and motor output, but not to visual stimuli or Stroop adaptation

    PubMed Central

    Wallentin, Mikkel; Skakkebæk, Anne; Bojesen, Anders; Fedder, Jens; Laurberg, Peter; Østergaard, John R.; Hertz, Jens Michael; Pedersen, Anders Degn; Gravholt, Claus Højbjerg

    2016-01-01

    Klinefelter syndrome (47, XXY) (KS) is a genetic syndrome characterized by the presence of an extra X chromosome and low level of testosterone, resulting in a number of neurocognitive abnormalities, yet little is known about brain function. This study investigated the fMRI-BOLD response from KS relative to a group of Controls to basic motor, perceptual, executive and adaptation tasks. Participants (N: KS = 49; Controls = 49) responded to whether the words “GREEN” or “RED” were displayed in green or red (incongruent versus congruent colors). One of the colors was presented three times as often as the other, making it possible to study both congruency and adaptation effects independently. Auditory stimuli saying “GREEN” or “RED” had the same distribution, making it possible to study effects of perceptual modality as well as Frequency effects across modalities. We found that KS had an increased response to motor output in primary motor cortex and an increased response to auditory stimuli in auditory cortices, but no difference in primary visual cortices. KS displayed a diminished response to written visual stimuli in secondary visual regions near the Visual Word Form Area, consistent with the widespread dyslexia in the group. No neural differences were found in inhibitory control (Stroop) or in adaptation to differences in stimulus frequencies. Across groups we found a strong positive correlation between age and BOLD response in the brain's motor network with no difference between groups. No effects of testosterone level or brain volume were found. In sum, the present findings suggest that auditory and motor systems in KS are selectively affected, perhaps as a compensatory strategy, and that this is not a systemic effect as it is not seen in the visual system. PMID:26958463

  6. In-vivo imaging of the photoreceptor mosaic in retinal dystrophies and correlations with visual function

    SciTech Connect

    Choi, S; Doble, N; Hardy, J; Jones, S; Keltner, J; Olivier, S; Werner, J S

    2005-10-26

    To relate in-vivo microscopic retinal changes to visual function assessed with clinical tests in patients with various forms of retinal dystrophies. The UC Davis Adaptive Optics (AO) Fundus Camera was used to acquire in-vivo retinal images at the cellular level. Visual function tests, consisting of visual field analysis, multifocal electroretinography (mfERG), contrast sensitivity and color vision measures, were performed on all subjects. Five patients with different forms of retinal dystrophies and three control subjects were recruited. Cone densities were quantified for all retinal images. In all images of diseased retinas, there were extensive areas of dark space between groups of photoreceptors, where no cone photoreceptors were evident. These irregular features were not seen in healthy retinas, but were characteristic features in fundi with retinal dystrophies. There was a correlation between functional vision loss and the extent to which the irregularities occurred in retinal images. Cone densities were found to decrease with an associated decrease in retinal function. AO fundus photography is a reliable technique for assessing and quantifying the changes in the photoreceptor layer as disease progresses. Furthermore, this technique can be useful in cases where visual function tests give borderline or ambiguous results, as it allows visualization of individual photoreceptors.

  7. A functional microcircuit for cat visual cortex.

    PubMed Central

    Douglas, R J; Martin, K A

    1991-01-01

    1. We have studied in vivo the intracellular responses of neurones in cat visual cortex to electrical pulse stimulation of the cortical afferents and have developed a microcircuit that simulates much of the experimental data. 2. Inhibition and excitation are not separable events, because individual neurones are embedded in microcircuits that contribute strong population effects. Synchronous electrical activation of the cortex inevitably set in motion a sequence of excitation and inhibition in every neurone we recorded. The temporal form of this response depends on the cortical layer in which the neurone is located. Superficial layer (layers 2+3) pyramidal neurones show a more marked polysynaptic excitatory phase than the pyramids of the deep layers (layers 5+6). 3. Excitatory effects on pyramidal neurones, particularly the superficial layer pyramids, are in general not due to monosynaptic input from thalamus, but polysynaptic input from cortical pyramids. Since the thalamic input is transient it does not provide the major, sustained excitation arriving at any cortical neurone. Instead the intracortical excitatory connections provide the major component of the excitation. 4. The polysynaptic excitatory response would be sustained well after the stimulus, were it not for the suppressive effect of intracortical inhibition induced by the pulse stimulation. 5. Intracellular recording combined with ionophoresis of gamma-aminobutyric acid (GABA) agonists and antagonists showed that intracortical inhibition is mediated by GABAA and GABAB receptors. The GABAA component occurs in the early phase of the impulse response. It is reflected in the strong hyperpolarization that follows the excitatory response and lasts about 50 ms. The GABAB component occurs in the late phase of the response, and is reflected in a sustained hyperpolarization that lasts some 200-300 ms. Both components are seen in all cortical pyramidal neurones. However, the GABAA component appears more powerful

  8. The selectivity of responses to red-green colour and achromatic contrast in the human visual cortex: an fMRI adaptation study.

    PubMed

    Mullen, Kathy T; Chang, Dorita H F; Hess, Robert F

    2015-12-01

    There is controversy as to how responses to colour in the human brain are organized within the visual pathways. A key issue is whether there are modular pathways that respond selectively to colour or whether there are common neural substrates for both colour and achromatic (Ach) contrast. We used functional magnetic resonance imaging (fMRI) adaptation to investigate the responses of early and extrastriate visual areas to colour and Ach contrast. High-contrast red-green (RG) and Ach sinewave rings (0.5 cycles/degree, 2 Hz) were used as both adapting stimuli and test stimuli in a block design. We found robust adaptation to RG or Ach contrast in all visual areas. Cross-adaptation between RG and Ach contrast occurred in all areas indicating the presence of integrated, colour and Ach responses. Notably, we revealed contrasting trends for the two test stimuli. For the RG test, unselective processing (robust adaptation to both RG and Ach contrast) was most evident in the early visual areas (V1 and V2), but selective responses, revealed as greater adaptation between the same stimuli than cross-adaptation between different stimuli, emerged in the ventral cortex, in V4 and VO in particular. For the Ach test, unselective responses were again most evident in early visual areas but Ach selectivity emerged in the dorsal cortex (V3a and hMT+). Our findings support a strong presence of integrated mechanisms for colour and Ach contrast across the visual hierarchy, with a progression towards selective processing in extrastriate visual areas.

  9. Guidelines for Assessing the Need for Adaptive Devices for Visually Impaired Pedestrians at Signalized Intersections.

    ERIC Educational Resources Information Center

    Gallagher, Brian R.; de Oca, Patricia Montes

    1998-01-01

    Presents guidelines for orientation and mobility instructors and traffic engineers to assess the need for adaptive devices to make crosswalks at signalized intersections accessible to pedestrians with visual impairments. The discussions of audible and tactile pedestrian devices, along with case examples, distinguish when each device should be…

  10. Cross-Cultural Adaptation of a Developmental Assessment for Arabic-Speaking Children with Visual Impairment

    ERIC Educational Resources Information Center

    Macrine, Sheila L.; Heji, Hayat; Sabri, Amel; Dalton, Sara

    2015-01-01

    Developmental screening has become an established component of child health programs in many developed countries. The research objective of this project was to translate and adapt a developmental assessment (Oregon Project Skills Inventory) for use with young children with visual impairments who speak Arabic. The study was prompted by the lack of…

  11. Biological clocks and visual systems in cave-adapted animals at the dawn of speleogenomics.

    PubMed

    Friedrich, Markus

    2013-07-01

    Cave-adapted animals are characterized by extreme reduction or complete absence of eyes, reflecting their lack of exposure to daylight. Given the overall constancy of abiotic variables in the cave environment, one would also expect the relaxation and eventual loss of circadian rhythms, and with it, the regressive evolution of the underlying genetic biological clock. Remarkably, however, recent behavioral and molecular studies converge with earlier evidence that the biological clock remains conserved in cave-adapted species. Reviewing the structural and behavioral data on the relationship between the visual system and the biological clock in cave species, I assess the potential of deep sequencing for elucidating their evolutionary conservation and adaptive significance in the subterranean fauna. The combined evidence confirms the widespread conservation both of the visual system and of the behavior regulated by the biological clock in cave species. The data from over 40 vertebrate and arthropod species further reveal that the absence of activity rhythms is correlated with the regression of the visual system. At the same time, the network of biological clock genes is likely to be generally conserved in cave species, regulating rhythmic behaviors in response to non-visual cycling variables as well as organismal homeostasis. Arrhythmic, eyeless species of cave beetles emerge as the most stringent choice for using deep-sequencing approaches to test and explore the conservation of the biological clock, independently of the visual system.

  12. Nonlinear functional approximation with networks using adaptive neurons

    NASA Technical Reports Server (NTRS)

    Tawel, Raoul

    1992-01-01

    A novel mathematical framework for the rapid learning of nonlinear mappings and topological transformations is presented. It is based on allowing the neuron's parameters to adapt as a function of learning. This fully recurrent adaptive neuron model (ANM) has been successfully applied to complex nonlinear function approximation problems such as the highly degenerate inverse kinematics problem in robotics.

  13. The Anatomical and Functional Organization of the Human Visual Pulvinar

    PubMed Central

    Pinsk, Mark A.; Kastner, Sabine

    2015-01-01

    The pulvinar is the largest nucleus in the primate thalamus and contains extensive, reciprocal connections with visual cortex. Although the anatomical and functional organization of the pulvinar has been extensively studied in old and new world monkeys, little is known about the organization of the human pulvinar. Using high-resolution functional magnetic resonance imaging at 3 T, we identified two visual field maps within the ventral pulvinar, referred to as vPul1 and vPul2. Both maps contain an inversion of contralateral visual space with the upper visual field represented ventrally and the lower visual field represented dorsally. vPul1 and vPul2 border each other at the vertical meridian and share a representation of foveal space with iso-eccentricity lines extending across areal borders. Additional, coarse representations of contralateral visual space were identified within ventral medial and dorsal lateral portions of the pulvinar. Connectivity analyses on functional and diffusion imaging data revealed a strong distinction in thalamocortical connectivity between the dorsal and ventral pulvinar. The two maps in the ventral pulvinar were most strongly connected with early and extrastriate visual areas. Given the shared eccentricity representation and similarity in cortical connectivity, we propose that these two maps form a distinct visual field map cluster and perform related functions. The dorsal pulvinar was most strongly connected with parietal and frontal areas. The functional and anatomical organization observed within the human pulvinar was similar to the organization of the pulvinar in other primate species. SIGNIFICANCE STATEMENT The anatomical organization and basic response properties of the visual pulvinar have been extensively studied in nonhuman primates. Yet, relatively little is known about the functional and anatomical organization of the human pulvinar. Using neuroimaging, we found multiple representations of visual space within the ventral

  14. Functional Connectivity Patterns of Visual Cortex Reflect its Anatomical Organization.

    PubMed

    Genç, Erhan; Schölvinck, Marieke Louise; Bergmann, Johanna; Singer, Wolf; Kohler, Axel

    2016-09-01

    The brain is continuously active, even without external input or task demands. This so-called resting-state activity exhibits a highly specific spatio-temporal organization. However, how exactly these activity patterns map onto the anatomical and functional architecture of the brain is still unclear. We addressed this question in the human visual cortex. We determined the representation of the visual field in visual cortical areas of 44 subjects using fMRI and examined resting-state correlations between these areas along the visual hierarchy, their dorsal and ventral segments, and between subregions representing foveal versus peripheral parts of the visual field. We found that retinotopically corresponding regions, particularly those representing peripheral visual fields, exhibit strong correlations. V1 displayed strong internal correlations between its dorsal and ventral segments and the highest correlation with LGN compared with other visual areas. In contrast, V2 and V3 showed weaker correlations with LGN and stronger between-area correlations, as well as with V4 and hMT+. Interhemispheric correlations between homologous areas were especially strong. These correlation patterns were robust over time and only marginally altered under task conditions. These results indicate that resting-state fMRI activity closely reflects the anatomical organization of the visual cortex both with respect to retinotopy and hierarchy.

  15. Neural signatures of adaptive post-error adjustments in visual search.

    PubMed

    Steinhauser, Robert; Maier, Martin E; Steinhauser, Marco

    2017-02-22

    Errors in speeded choice tasks can lead to post-error adjustments both on the behavioral and on the neural level. There is an ongoing debate whether such adjustments result from adaptive processes that serve to optimize performance or whether they reflect interference from error monitoring or attentional orientation. The present study aimed at identifying adaptive adjustments in a two-stage visual search task, in which participants had to select and subsequently identify a target stimulus presented to the left or right visual hemifield. Target selection and identification can be measured by two distinct event-related potentials, the N2pc and the SPCN. Using a decoder analysis based on multivariate pattern analysis, we were able to isolate the processing stages related to error sources and post-error adjustments. Whereas errors were linked to deviations in the N2pc and the SPCN, only for the N2pc we identified a post-error adjustment, which exhibits key features of source-specific adaptivity. While errors were associated with an increased N2pc, post-error adjustments consisted in an N2pc decrease. We interpret this as an adaptive adjustment of target selection to prevent errors due to disproportionate processing of the task-irrelevant target location. Our study thus provides evidence for adaptive post-error adjustments in visual search.

  16. A review of visual perception mechanisms that regulate rapid adaptive camouflage in cuttlefish.

    PubMed

    Chiao, Chuan-Chin; Chubb, Charles; Hanlon, Roger T

    2015-09-01

    We review recent research on the visual mechanisms of rapid adaptive camouflage in cuttlefish. These neurophysiologically complex marine invertebrates can camouflage themselves against almost any background, yet their ability to quickly (0.5-2 s) alter their body patterns on different visual backgrounds poses a vexing challenge: how to pick the correct body pattern amongst their repertoire. The ability of cuttlefish to change appropriately requires a visual system that can rapidly assess complex visual scenes and produce the motor responses-the neurally controlled body patterns-that achieve camouflage. Using specifically designed visual backgrounds and assessing the corresponding body patterns quantitatively, we and others have uncovered several aspects of scene variation that are important in regulating cuttlefish patterning responses. These include spatial scale of background pattern, background intensity, background contrast, object edge properties, object contrast polarity, object depth, and the presence of 3D objects. Moreover, arm postures and skin papillae are also regulated visually for additional aspects of concealment. By integrating these visual cues, cuttlefish are able to rapidly select appropriate body patterns for concealment throughout diverse natural environments. This sensorimotor approach of studying cuttlefish camouflage thus provides unique insights into the mechanisms of visual perception in an invertebrate image-forming eye.

  17. In Vivo Imaging of the Photoreceptor Mosaic in Retinal Dystrophies and Correlations with Visual Function

    PubMed Central

    Choi, Stacey S.; Doble, Nathan; Hardy, Joseph L.; Jones, Steven M.; Keltner, John L.; Olivier, Scot S.; Werner, John S.

    2008-01-01

    Purpose To relate in vivo microscopic retinal changes to visual function in patients who have various forms of retinal dystrophy. Methods The UC Davis Adaptive Optics (AO) fundus camera was used to acquire in vivo retinal images at the cellular level. Visual function tests consisting of visual fields, multifocal electroretinography (mfERG), and contrast sensitivity were measured in all subjects by using stimuli that were coincident with areas imaged. Five patients with different forms of retinal dystrophy and three control subjects were recruited. Cone densities were quantified for all retinal images. Results In all images of diseased retinas, there were extensive areas of dark space between groups of photoreceptors, where no cone photoreceptors were evident. These irregular features were not seen in healthy retinas, but were apparent in patients with retinal dystrophy. There were significant correlations between functional vision losses and the extent to which these irregularities, quantified by cone density, occurred in retinal images. Conclusions AO fundus imaging is a reliable technique for assessing and quantifying the changes in the photoreceptor layer as disease progresses. Furthermore, this technique can be useful in cases where visual function tests provide borderline or ambiguous results, as it allows visualization of individual photoreceptors. PMID:16639019

  18. Docosahexaenoic acid and visual functioning in preterm infants: a review.

    PubMed

    Molloy, Carly; Doyle, Lex W; Makrides, Maria; Anderson, Peter J

    2012-12-01

    Preterm children are at risk for a number of visual impairments which can be important for a range of other more complex visuocognitive tasks reliant on visual information. Despite the relatively high incidence of visual impairments in this group there are no good predictors that would allow early identification of those at risk for adverse outcomes. Several lines of evidence suggest that docosahexaenoic acid (DHA) supplementation for preterm infants may improve outcomes in this area. For example, diets deficient in the long-chain polyunsaturated fatty acid DHA have been shown to reduce its concentration in the cerebral cortex and retina, which interferes with physiological processes important for cognition and visual functioning. Further, various studies with pregnant and lactating women, as well as formula-fed infants, have demonstrated a general trend that supplementation with dietary DHA is associated with better childhood outcomes on tests of visual and cognitive development over the first year of life. However, research to date has several methodological limitations, including concentrations of DHA supplementation that have been too low to emulate the in utero accretion of DHA, using single measures of visual acuity to make generalised assumptions about the entire visual system, and little attempt to match what we know about inadequate DHA and structural ramifications with how specific functions may be affected. The objective of this review is to consider the role of DHA in the context of visual processing with a specific emphasis on preterm infants and to illustrate how future research may benefit from marrying what we know about structural consequences to inadequate DHA with functional outcomes that likely have far-reaching ramifications. Factors worth considering for clinical neuropsychological evaluation are also discussed.

  19. InfoStar: An Adaptive Visual Analytics Platform for Mobile Devices

    SciTech Connect

    Sanfilippo, Antonio P.; May, Richard A.; Danielson, Gary R.; Baddeley, Bob L.; Riensche, Roderick M.; Collins, Sharon; Thornton, Susan E.; Washington, Kenneth; Schrager, Matt; Van Randwyk, Jamie; Borchers, Bob; Gatchell, Doug

    2005-05-09

    We present the design and implementation of InfoStar, an adaptive Visual Analytics platform for mobile devices such a PDAs, laptops, Tablet PCs and mobile phones. InfoStar extends the reach of visual analytics technology beyond the traditional desktop paradigm to provide ubiquitous access to inter-active visualizations of information spaces. These visualizations are critical in addressing the knowledge needs of human agents operating in the field, in areas as diverse as business, homeland security, law enforcement, protective services, emergency medical services and scientific discovery. We describe an initial real world deployment of this technology, in which the InfoStar platform has been used to offer mobile access to scheduling and venue information to conference attendees at Supercomputing 2004.

  20. InfoStar : an adaptive visual analytics platform for mobile devices.

    SciTech Connect

    Gatchell, Doug; Borchers, Bob; Schrager, Matthew A.; Thornton, Susan; Collins, Sharon; Van Randwyk, Jamie A.; Danielson, Gary; Riensche, Rick; May, Richard; Baddeley, Bob; Sanfilippo, Antonio; Washington, Kenneth Edward

    2005-03-01

    We present the design and implementation of InfoStar, an adaptive Visual Analytics platform for mobile devices such a PDAs, laptops, Tablet PCs and mobile phones. InfoStar extends the reach of visual analytics technology beyond the traditional desktop paradigm to provide ubiquitous access to inter-active visualizations of information spaces. These visualizations are critical in addressing the knowledge needs of human agents operating in the field, in areas as diverse as business, homeland security, law enforcement, protective services, emergency medical services and scientific discovery. We describe an initial real world deployment of this technology, in which the InfoStar platform has been used to offer mobile access to scheduling and venue information to conference attendees at Supercomputing 2004.

  1. Visual Arrestin 1 Contributes to Cone Photoreceptor Survival and Light Adaptation

    PubMed Central

    Brown, Bruce M.; Ramirez, Teresa; Rife, Lawrence

    2010-01-01

    Purpose. To evaluate morphologic and functional contributions of Arrestin 1 (Arr1) and Arrestin 4 (Arr4) in cone photoreceptors, the authors examined the phenotypes of visual arrestin knockout mice (Arr1−/−, Arr4−/−, Arr1−/−Arr4−/− [Arr-DKO]) reared in darkness. Methods. Retinal rods and cones were evaluated in wild-type (WT), Arr1−/−, Arr4−/−, and Arr-DKO mice using quantitative morphologic analysis, immunoblot, immunohistochemistry, TUNEL, and electroretinographic (ERG) techniques. Results. Compared with either Arr4−/− or WT, Arr1−/− and Arr-DKO mice had increased apoptotic nuclei in their retinal outer nuclear layer (ONL) at postnatal day (P) 22. By P60, cone density was significantly diminished, but the ONL appeared normal. After 1 minute of background illumination, cone ERG b-wave amplitudes were similar in WT and all Arr KO mice. However, by 3 minutes and continuing through 15 minutes of light adaptation, the cone b-wave amplitudes of WT and Arr4−/− mice increased significantly over those of the Arr1−/− and Arr-DKO mice, which demonstrated no cone b-wave amplitude increase. In contrast, ERG flicker analysis after the 15-minute light adaptation period demonstrated no loss in amplitude for either Arr1−/− or Arr4−/− mice, whereas Arr-DKO had significantly lower amplitudes. When Arr1 expression was restored in Arr1−/− mice (+p48Arr1−/−), normal cone density and light-adapted ERG b-wave amplitudes were observed. Conclusions. In the adult dark-reared Arr1−/− and Arr-DKO mice, viable cones diminish over time. Arr1 expression is essential for cone photoreceptor survival and light adaptation, whereas either Arr1 or Arr4 is necessary for maintaining normal flicker responses. PMID:20019357

  2. Improving Sensorimotor Function and Adaptation using Stochastic Vestibular Stimulation

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    Astronauts experience sensorimotor changes during adaption to G-transitions that occur when entering and exiting microgravity. Post space flight, these sensorimotor disturbances can include postural and gait instability, visual performance changes, manual control disruptions, spatial disorientation, and motion sickness, all of which can hinder the operational capabilities of the astronauts. Crewmember safety would be significantly increased if sensorimotor changes brought on by gravitational changes could be mitigated and adaptation could be facilitated. The goal of this research is to investigate and develop the use of electrical stochastic vestibular stimulation (SVS) as a countermeasure to augment sensorimotor function and facilitate adaptation. For this project, SVS will be applied via electrodes on the mastoid processes at imperceptible amplitude levels. We hypothesize that SVS will improve sensorimotor performance through the phenomena of stochastic resonance, which occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. In line with the theory of stochastic resonance, a specific optimal level of SVS will be found and tested for each subject [1]. Three experiments are planned to investigate the use of SVS in sensory-dependent tasks and performance. The first experiment will aim to demonstrate stochastic resonance in the vestibular system through perception based motion recognition thresholds obtained using a 6-degree of freedom Stewart platform in the Jenks Vestibular Laboratory at Massachusetts Eye and Ear Infirmary. A range of SVS amplitudes will be applied to each subject and the subjectspecific optimal SVS level will be identified as that which results in the lowest motion recognition threshold, through previously established, well developed methods [2,3,4]. The second experiment will investigate the use of optimal SVS in facilitating sensorimotor adaptation to system

  3. A new method to measure higher visual functions in an immersive environment

    PubMed Central

    2014-01-01

    Background Higher visual functions can be defined as cognitive processes responsible for object recognition, color and shape perception, and motion detection. People with impaired higher visual functions after unilateral brain lesion are often tested with paper pencil tests, but such tests do not assess the degree of interaction between the healthy brain hemisphere and the impaired one. Hence, visual functions are not tested separately in the contralesional and ipsilesional visual hemifields. Methods A new measurement setup, that involves real-time comparisons of shape and size of objects, orientation of lines, speed and direction of moving patterns, in the right or left visual hemifield, has been developed. The setup was implemented in an immersive environment like a hemisphere to take into account the effects of peripheral and central vision, and eventual visual field losses. Due to the non-flat screen of the hemisphere, a distortion algorithm was needed to adapt the projected images to the surface. Several approaches were studied and, based on a comparison between projected images and original ones, the best one was used for the implementation of the test. Fifty-seven healthy volunteers were then tested in a pilot study. A Satisfaction Questionnaire was used to assess the usability of the new measurement setup. Results The results of the distortion algorithm showed a structural similarity between the warped images and the original ones higher than 97%. The results of the pilot study showed an accuracy in comparing images in the two visual hemifields of 0.18 visual degrees and 0.19 visual degrees for size and shape discrimination, respectively, 2.56° for line orientation, 0.33 visual degrees/s for speed perception and 7.41° for recognition of motion direction. The outcome of the Satisfaction Questionnaire showed a high acceptance of the battery by the participants. Conclusions A new method to measure higher visual functions in an immersive environment was

  4. Seeing is believing: effects of visual contextual cues on learning and transfer of locomotor adaptation.

    PubMed

    Torres-Oviedo, Gelsy; Bastian, Amy J

    2010-12-15

    Devices such as robots or treadmills are often used to drive motor learning because they can create novel physical environments. However, the learning (i.e., adaptation) acquired on these devices only partially generalizes to natural movements. What determines the specificity of motor learning, and can this be reliably made more general? Here we investigated the effect of visual cues on the specificity of split-belt walking adaptation. We systematically removed vision to eliminate the visual-proprioceptive mismatch that is a salient cue specific to treadmills: vision indicates that we are not moving while leg proprioception indicates that we are. We evaluated the adaptation of temporal and spatial features of gait (i.e., timing and location of foot landing), their transfer to walking over ground, and washout of adaptation when subjects returned to the treadmill. Removing vision during both training (i.e., on the treadmill) and testing (i.e., over ground) strongly improved the transfer of treadmill adaptation to natural walking. Removing vision only during training increased transfer of temporal adaptation, whereas removing vision only during testing increased the transfer of spatial adaptation. This dissociation reveals differences in adaptive mechanisms for temporal and spatial features of walking. Finally training without vision increased the amount that was learned and was linked to the variability in the behavior during adaptation. In conclusion, contextual cues can be manipulated to modulate the magnitude, transfer, and washout of device-induced learning in humans. These results bring us closer to our ultimate goal of developing rehabilitation strategies that improve movements beyond the clinical setting.

  5. Retinol Dehydrogenases Regulate Vitamin A Metabolism for Visual Function

    PubMed Central

    Sahu, Bhubanananda; Maeda, Akiko

    2016-01-01

    The visual system produces visual chromophore, 11-cis-retinal from dietary vitamin A, all-trans-retinol making this vitamin essential for retinal health and function. These metabolic events are mediated by a sequential biochemical process called the visual cycle. Retinol dehydrogenases (RDHs) are responsible for two reactions in the visual cycle performed in retinal pigmented epithelial (RPE) cells, photoreceptor cells and Müller cells in the retina. RDHs in the RPE function as 11-cis-RDHs, which oxidize 11-cis-retinol to 11-cis-retinal in vivo. RDHs in rod photoreceptor cells in the retina work as all-trans-RDHs, which reduce all-trans-retinal to all-trans-retinol. Dysfunction of RDHs can cause inherited retinal diseases in humans. To facilitate further understanding of human diseases, mouse models of RDHs-related diseases have been carefully examined and have revealed the physiological contribution of specific RDHs to visual cycle function and overall retinal health. Herein we describe the function of RDHs in the RPE and the retina, particularly in rod photoreceptor cells, their regulatory properties for retinoid homeostasis and future therapeutic strategy for treatment of retinal diseases. PMID:27879662

  6. Imaging of the Functional and Dysfunctional Visual System

    PubMed Central

    DeYoe, Edgar A.; Ulmer, John L.; Mueller, Wade M.; Sabsevitz, David S.; Reitsma, Danielle C.; Pillai, Jay J.

    2015-01-01

    Functional magnetic resonance imaging (fMRI) is used clinically to map the visual cortex before brain surgery or other invasive treatments to achieve an optimal balance between therapeutic effect and the avoidance of postoperative vision deficits. Clinically optimized stimuli, analyses, and displays permit identification of cortical subregions supporting high-acuity central vision that are critical for reading and other essential visual functions. A novel data display permits instant appreciation of the functional relationship between the pattern of fMRI brain activation and the pattern of vision loss and preservation within the patient's field of view. Neurovascular uncoupling and its detection in the visual cortex are key issues for the interpretation of fMRI results in patients with existing brain pathology. PMID:26233858

  7. Perceptual suppression revealed by adaptive multi-scale entropy analysis of local field potential in monkey visual cortex.

    PubMed

    Hu, Meng; Liang, Hualou

    2013-04-01

    Generalized flash suppression (GFS), in which a salient visual stimulus can be rendered invisible despite continuous retinal input, provides a rare opportunity to directly study the neural mechanism of visual perception. Previous work based on linear methods, such as spectral analysis, on local field potential (LFP) during GFS has shown that the LFP power at distinctive frequency bands are differentially modulated by perceptual suppression. Yet, the linear method alone may be insufficient for the full assessment of neural dynamic due to the fundamentally nonlinear nature of neural signals. In this study, we set forth to analyze the LFP data collected from multiple visual areas in V1, V2 and V4 of macaque monkeys while performing the GFS task using a nonlinear method - adaptive multi-scale entropy (AME) - to reveal the neural dynamic of perceptual suppression. In addition, we propose a new cross-entropy measure at multiple scales, namely adaptive multi-scale cross-entropy (AMCE), to assess the nonlinear functional connectivity between two cortical areas. We show that: (1) multi-scale entropy exhibits percept-related changes in all three areas, with higher entropy observed during perceptual suppression; (2) the magnitude of the perception-related entropy changes increases systematically over successive hierarchical stages (i.e. from lower areas V1 to V2, up to higher area V4); and (3) cross-entropy between any two cortical areas reveals higher degree of asynchrony or dissimilarity during perceptual suppression, indicating a decreased functional connectivity between cortical areas. These results, taken together, suggest that perceptual suppression is related to a reduced functional connectivity and increased uncertainty of neural responses, and the modulation of perceptual suppression is more effective at higher visual cortical areas. AME is demonstrated to be a useful technique in revealing the underlying dynamic of nonlinear/nonstationary neural signal.

  8. Hierarchical organization of brain functional networks during visual tasks.

    PubMed

    Zhuo, Zhao; Cai, Shi-Min; Fu, Zhong-Qian; Zhang, Jie

    2011-09-01

    The functional network of the brain is known to demonstrate modular structure over different hierarchical scales. In this paper, we systematically investigated the hierarchical modular organizations of the brain functional networks that are derived from the extent of phase synchronization among high-resolution EEG time series during a visual task. In particular, we compare the modular structure of the functional network from EEG channels with that of the anatomical parcellation of the brain cortex. Our results show that the modular architectures of brain functional networks correspond well to those from the anatomical structures over different levels of hierarchy. Most importantly, we find that the consistency between the modular structures of the functional network and the anatomical network becomes more pronounced in terms of vision, sensory, vision-temporal, motor cortices during the visual task, which implies that the strong modularity in these areas forms the functional basis for the visual task. The structure-function relationship further reveals that the phase synchronization of EEG time series in the same anatomical group is much stronger than that of EEG time series from different anatomical groups during the task and that the hierarchical organization of functional brain network may be a consequence of functional segmentation of the brain cortex.

  9. Hierarchical organization of brain functional networks during visual tasks

    NASA Astrophysics Data System (ADS)

    Zhuo, Zhao; Cai, Shi-Min; Fu, Zhong-Qian; Zhang, Jie

    2011-09-01

    The functional network of the brain is known to demonstrate modular structure over different hierarchical scales. In this paper, we systematically investigated the hierarchical modular organizations of the brain functional networks that are derived from the extent of phase synchronization among high-resolution EEG time series during a visual task. In particular, we compare the modular structure of the functional network from EEG channels with that of the anatomical parcellation of the brain cortex. Our results show that the modular architectures of brain functional networks correspond well to those from the anatomical structures over different levels of hierarchy. Most importantly, we find that the consistency between the modular structures of the functional network and the anatomical network becomes more pronounced in terms of vision, sensory, vision-temporal, motor cortices during the visual task, which implies that the strong modularity in these areas forms the functional basis for the visual task. The structure-function relationship further reveals that the phase synchronization of EEG time series in the same anatomical group is much stronger than that of EEG time series from different anatomical groups during the task and that the hierarchical organization of functional brain network may be a consequence of functional segmentation of the brain cortex.

  10. Multilevel adaptive solution procedure for material nonlinear problems in visual programming environment

    SciTech Connect

    Kim, D.; Ghanem, R.

    1994-12-31

    Multigrid solution technique to solve a material nonlinear problem in a visual programming environment using the finite element method is discussed. The nonlinear equation of equilibrium is linearized to incremental form using Newton-Rapson technique, then multigrid solution technique is used to solve linear equations at each Newton-Rapson step. In the process, adaptive mesh refinement, which is based on the bisection of a pair of triangles, is used to form grid hierarchy for multigrid iteration. The solution process is implemented in a visual programming environment with distributed computing capability, which enables more intuitive understanding of solution process, and more effective use of resources.

  11. Visual function affects prosocial behaviors in older adults.

    PubMed

    Teoli, Dac A; Smith, Merideth D; Leys, Monique J; Jain, Priyanka; Odom, J Vernon

    2016-02-01

    Eye-related pathological conditions such as glaucoma, diabetic retinopathy, and age-related macular degeneration commonly lead to decreased peripheral/central field, decreased visual acuity, and increased functional disability. We sought to answer if relationships exist between measures of visual function and reported prosocial behaviors in an older adult population with eye-related diagnoses. The sample consisted of adults, aged ≥ 60 years old, at an academic hospital's eye institute. Vision ranged from normal to severe impairment. Medical charts determined the visual acuities, ocular disease, duration of disease (DD), and visual fields (VF). Measures of giving help were via validated questionnaires on giving formal support (GFS) and giving informal support; measures of help received were perceived support (PS) and informal support received (ISR). ISR had subscales: tangible support (ISR-T), emotional support (ISR-E), and composite (ISR-C). Visual acuities of the better and worse seeing eyes were converted to LogMAR values. VF information converted to a 4-point rating scale of binocular field loss severity. DD was in years. Among 96 participants (mean age 73.28; range 60-94), stepwise regression indicated a relationship of visual variables to GFS (p < 0.05; Multiple R (2) = 0.1679 with acuity-better eye, VF rating, and DD), PS (p < 0.05; Multiple R (2) = 0.2254 with acuity-better eye), ISR-C (p < 0.05; Multiple R (2) = 0.041 with acuity-better eye), and ISR-T (p < 0.05; Multiple R (2) = 0.1421 with acuity-better eye). The findings suggest eye-related conditions can impact levels and perceptions of support exchanges. Our data reinforces the importance of visual function as an influence on prosocial behavior in older adults.

  12. Effect of microgravity on visual contrast threshold during STS Shuttle missions: Visual Function Tester-Model 2 (VFT-2)

    NASA Technical Reports Server (NTRS)

    Oneal, Melvin R.; Task, H. Lee; Genco, Louis V.

    1992-01-01

    Viewgraphs on effect of microgravity on visual contrast threshold during STS shuttle missions are presented. The purpose, methods, and results are discussed. The visual function tester model 2 is used.

  13. Shape outlier detection and visualization for functional data: the outliergram.

    PubMed

    Arribas-Gil, Ana; Romo, Juan

    2014-10-01

    We propose a new method to visualize and detect shape outliers in samples of curves. In functional data analysis, we observe curves defined over a given real interval and shape outliers may be defined as those curves that exhibit a different shape from the rest of the sample. Whereas magnitude outliers, that is, curves that lie outside the range of the majority of the data, are in general easy to identify, shape outliers are often masked among the rest of the curves and thus difficult to detect. In this article, we exploit the relationship between two measures of depth for functional data to help to visualize curves in terms of shape and to develop an algorithm for shape outlier detection. We illustrate the use of the visualization tool, the outliergram, through several examples and analyze the performance of the algorithm on a simulation study. Finally, we apply our method to assess cluster quality in a real set of time course microarray data.

  14. Auditory to Visual Cross-Modal Adaptation for Emotion: Psychophysical and Neural Correlates.

    PubMed

    Wang, Xiaodong; Guo, Xiaotao; Chen, Lin; Liu, Yijun; Goldberg, Michael E; Xu, Hong

    2016-01-04

    Adaptation is fundamental in sensory processing and has been studied extensively within the same sensory modality. However, little is known about adaptation across sensory modalities, especially in the context of high-level processing, such as the perception of emotion. Previous studies have shown that prolonged exposure to a face exhibiting one emotion, such as happiness, leads to contrastive biases in the perception of subsequently presented faces toward the opposite emotion, such as sadness. Such work has shown the importance of adaptation in calibrating face perception based on prior visual exposure. In the present study, we showed for the first time that emotion-laden sounds, like laughter, adapt the visual perception of emotional faces, that is, subjects more frequently perceived faces as sad after listening to a happy sound. Furthermore, via electroencephalography recordings and event-related potential analysis, we showed that there was a neural correlate underlying the perceptual bias: There was an attenuated response occurring at ∼ 400 ms to happy test faces and a quickened response to sad test faces, after exposure to a happy sound. Our results provide the first direct evidence for a behavioral cross-modal adaptation effect on the perception of facial emotion, and its neural correlate.

  15. The multisensory function of the human primary visual cortex.

    PubMed

    Murray, Micah M; Thelen, Antonia; Thut, Gregor; Romei, Vincenzo; Martuzzi, Roberto; Matusz, Pawel J

    2016-03-01

    It has been nearly 10 years since Ghazanfar and Schroeder (2006) proposed that the neocortex is essentially multisensory in nature. However, it is only recently that sufficient and hard evidence that supports this proposal has accrued. We review evidence that activity within the human primary visual cortex plays an active role in multisensory processes and directly impacts behavioural outcome. This evidence emerges from a full pallet of human brain imaging and brain mapping methods with which multisensory processes are quantitatively assessed by taking advantage of particular strengths of each technique as well as advances in signal analyses. Several general conclusions about multisensory processes in primary visual cortex of humans are supported relatively solidly. First, haemodynamic methods (fMRI/PET) show that there is both convergence and integration occurring within primary visual cortex. Second, primary visual cortex is involved in multisensory processes during early post-stimulus stages (as revealed by EEG/ERP/ERFs as well as TMS). Third, multisensory effects in primary visual cortex directly impact behaviour and perception, as revealed by correlational (EEG/ERPs/ERFs) as well as more causal measures (TMS/tACS). While the provocative claim of Ghazanfar and Schroeder (2006) that the whole of neocortex is multisensory in function has yet to be demonstrated, this can now be considered established in the case of the human primary visual cortex.

  16. Using a Function Generator to Produce Auditory and Visual Demonstrations.

    ERIC Educational Resources Information Center

    Woods, Charles B.

    1998-01-01

    Identifies a function generator as an instrument that produces time-varying electrical signals of frequency, wavelength, and amplitude. Sending these signals to a speaker or a light-emitting diode can demonstrate how specific characteristics of auditory or visual stimuli relate to perceptual experiences. Provides specific instructions for using…

  17. A candidate multimodal functional genetic network for thermal adaptation

    PubMed Central

    Pathak, Rachana; Prajapati, Indira; Bankston, Shannon; Thompson, Aprylle; Usher, Jaytriece; Isokpehi, Raphael D.

    2014-01-01

    Vertebrate ectotherms such as reptiles provide ideal organisms for the study of adaptation to environmental thermal change. Comparative genomic and exomic studies can recover markers that diverge between warm and cold adapted lineages, but the genes that are functionally related to thermal adaptation may be difficult to identify. We here used a bioinformatics genome-mining approach to predict and identify functions for suitable candidate markers for thermal adaptation in the chicken. We first established a framework of candidate functions for such markers, and then compiled the literature on genes known to adapt to the thermal environment in different lineages of vertebrates. We then identified them in the genomes of human, chicken, and the lizard Anolis carolinensis, and established a functional genetic interaction network in the chicken. Surprisingly, markers initially identified from diverse lineages of vertebrates such as human and fish were all in close functional relationship with each other and more associated than expected by chance. This indicates that the general genetic functional network for thermoregulation and/or thermal adaptation to the environment might be regulated via similar evolutionarily conserved pathways in different vertebrate lineages. We were able to identify seven functions that were statistically overrepresented in this network, corresponding to four of our originally predicted functions plus three unpredicted functions. We describe this network as multimodal: central regulator genes with the function of relaying thermal signal (1), affect genes with different cellular functions, namely (2) lipoprotein metabolism, (3) membrane channels, (4) stress response, (5) response to oxidative stress, (6) muscle contraction and relaxation, and (7) vasodilation, vasoconstriction and regulation of blood pressure. This network constitutes a novel resource for the study of thermal adaptation in the closely related nonavian reptiles and other

  18. Longitudinal Investigation of Adaptive Functioning Following Conformal Irradiation for Pediatric Craniopharyngioma and Low-Grade Glioma

    SciTech Connect

    Netson, Kelli L.; Conklin, Heather M.; Wu, Shengjie; Xiong, Xiaoping; Merchant, Thomas E.

    2013-04-01

    Purpose: Children treated for brain tumors with conformal radiation therapy experience preserved cognitive outcomes. Early evidence suggests that adaptive functions or independent-living skills may be spared. This longitudinal investigation prospectively examined intellectual and adaptive functioning during the first 5 years following irradiation for childhood craniopharyngioma and low-grade glioma (LGG). The effect of visual impairment on adaptive outcomes was investigated. Methods and Materials: Children with craniopharyngioma (n=62) and LGG (n=77) were treated using conformal or intensity modulated radiation therapy. The median age was 8.05 years (3.21-17.64 years) and 8.09 years (2.20-19.27 years), respectively. Serial cognitive evaluations including measures of intelligence quotient (IQ) and the Vineland Adaptive Behavior Scales (VABS) were conducted at preirradiation baseline, 6 months after treatment, and annually through 5 years. Five hundred eighty-eight evaluations were completed during the follow-up period. Results: Baseline assessment revealed no deficits in IQ and VABS indices for children with craniopharyngioma, with significant (P<.05) longitudinal decline in VABS Communication and Socialization indices. Clinical factors associated with more rapid decline included females and preirradiation chemotherapy (interferon). The only change in VABS Daily Living Skills correlated with IQ change (r=0.34; P=.01) in children with craniopharyngioma. Children with LGG performed below population norms (P<.05) at baseline on VABS Communication, Daily Living Indices, and the Adaptive Behavior Composite, with significant (P<.05) longitudinal decline limited to VABS Communication. Older age at irradiation was a protective factor against longitudinal decline. Severe visual impairment did not independently correlate with poorer adaptive outcomes for either tumor group. Conclusions: There was relative sparing of postirradiation functional outcomes over time in this sample

  19. Restoration of visual function by enhancing conduction in regenerated axons

    PubMed Central

    Bei, Fengfeng; Lee, Henry Hing Cheong; Liu, Xuefeng; Gunner, Georgia; Jin, Hai; Ma, Long; Wang, Chen; Hou, lijun; Hensch, Takao K.; Frank, Eric; Sanes, Joshua R.; Chen, Chinfei; Fagiolini, Michela; He, Zhigang

    2016-01-01

    Although a number of repair strategies have been shown to promote axon outgrowth following neuronal injury in the mammalian central nervous system, it remains unclear whether regenerated axons establish functional synapses and support behavior. Here, in both juvenile and adult mice, we show that either PTEN and SOCS3 co-deletion, or co-overexpression of osteopontin (OPN)/insulin-like growth factor 1 (IGF1)/ciliary neurotrophic factor (CNTF), induces regrowth of retinal axons and formation of functional synapses in the superior colliculus (SC), but not significant recovery of visual function. Further analyses suggest that regenerated axons fail to conduct action potentials from the eye to the SC due to lack of myelination. Consistent with this idea, administration of voltage-gated potassium channel blockers restores conduction and results in increased visual acuity. Thus, enhancing both regeneration and conduction effectively improves function after optic nerve injury. PMID:26771493

  20. Closed-form expressions of some stochastic adapting equations for nonlinear adaptive activation function neurons.

    PubMed

    Fiori, Simone

    2003-12-01

    In recent work, we introduced nonlinear adaptive activation function (FAN) artificial neuron models, which learn their activation functions in an unsupervised way by information-theoretic adapting rules. We also applied networks of these neurons to some blind signal processing problems, such as independent component analysis and blind deconvolution. The aim of this letter is to study some fundamental aspects of FAN units' learning by investigating the properties of the associated learning differential equation systems.

  1. Eye-Hand Coordination during Visuomotor Adaptation with Different Rotation Angles: Effects of Terminal Visual Feedback

    PubMed Central

    Rand, Miya K.; Rentsch, Sebastian

    2016-01-01

    This study examined adaptive changes of eye-hand coordination during a visuomotor rotation task under the use of terminal visual feedback. Young adults made reaching movements to targets on a digitizer while looking at targets on a monitor where the rotated feedback (a cursor) of hand movements appeared after each movement. Three rotation angles (30°, 75° and 150°) were examined in three groups in order to vary the task difficulty. The results showed that the 30° group gradually reduced direction errors of reaching with practice and adapted well to the visuomotor rotation. The 75° group made large direction errors of reaching, and the 150° group applied a 180° reversal shift from early practice. The 75°and 150° groups, however, overcompensated the respective rotations at the end of practice. Despite these group differences in adaptive changes of reaching, all groups gradually adapted gaze directions prior to reaching from the target area to the areas related to the final positions of reaching during the course of practice. The adaptive changes of both hand and eye movements in all groups mainly reflected adjustments of movement directions based on explicit knowledge of the applied rotation acquired through practice. Only the 30° group showed small implicit adaptation in both effectors. The results suggest that by adapting gaze directions from the target to the final position of reaching based on explicit knowledge of the visuomotor rotation, the oculomotor system supports the limb-motor system to make precise preplanned adjustments of reaching directions during learning of visuomotor rotation under terminal visual feedback. PMID:27812093

  2. Adaptive update using visual models for lifting-based motion-compensated temporal filtering

    NASA Astrophysics Data System (ADS)

    Li, Song; Xiong, H. K.; Wu, Feng; Chen, Hong

    2005-03-01

    Motion compensated temporal filtering is a useful framework for fully scalable video compression schemes. However, when supposed motion models cannot represent a real motion perfectly, both the temporal high and the temporal low frequency sub-bands may contain artificial edges, which possibly lead to a decreased coding efficiency, and ghost artifacts appear in the reconstructed video sequence at lower bit rates or in case of temporal scaling. We propose a new technique that is based on utilizing visual models to mitigate ghosting artifacts in the temporal low frequency sub-bands. Specifically, we propose content adaptive update schemes where visual models are used to determine image dependent upper bounds on information to be updated. Experimental results show that the proposed algorithm can significantly improve subjective visual quality of the low-pass temporal frames and at the same time, coding performance can catch or exceed the classical update steps.

  3. An automated miniaturized Haploscope for testing binocular visual function

    NASA Technical Reports Server (NTRS)

    Decker, T. A.; Williams, R. E.; Kuether, C. L.; Wyman-Cornsweet, D.

    1976-01-01

    A computer-controlled binocular vision testing device has been developed as one part of a system designed for NASA to test the vision of astronauts during spaceflight. The device, called the Mark III Haploscope, utilizes semi-automated psychophysical test procedures to measure visual acuity, stereopsis, phorias, fixation disparity and accommodation/convergence relationships. All tests are self-administered, yield quantitative data and may be used repeatedly without subject memorization. Future applications of this programmable, compact device include its use as a clinical instrument to perform routine eye examinations or vision screening, and as a research tool to examine the effects of environment or work-cycle upon visual function.

  4. Comparative visual function in four piscivorous fishes inhabiting Chesapeake Bay.

    PubMed

    Horodysky, Andrij Z; Brill, Richard W; Warrant, Eric J; Musick, John A; Latour, Robert J

    2010-05-01

    Maintaining optimal visual performance is a difficult task in photodynamic coastal and estuarine waters because of the unavoidable tradeoffs between luminous sensitivity and spatial and temporal resolution, yet the visual systems of coastal piscivores remain understudied despite differences in their ecomorphology and microhabitat use. We therefore used electroretinographic techniques to describe the light sensitivities, temporal properties and spectral sensitivities of the visual systems of four piscivorous fishes common to coastal and estuarine waters of the western North Atlantic: striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), summer flounder (Paralichthys dentatus) and cobia (Rachycentron canadum). Benthic summer flounder exhibited higher luminous sensitivity and broader dynamic range than the three pelagic foragers. The former were at the more sensitive end of an emerging continuum for coastal fishes. By contrast, pelagic species were comparatively less sensitive, but showed larger day-night differences, consistent with their use of diel light-variant photic habitats. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of most species spanned 400-610 nm, with significant day-night differences in striped bass and bluefish. Anadromous striped bass additionally responded to longer wavelengths, similar to many freshwater fishes. Collectively, these results suggest that pelagic piscivores are well adapted to bright photoclimates, which may be at odds with the modern state of eutrified coastal and estuarine waters that they utilize. Recent anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may impede visually foraging piscivores, change selected prey, and eventually restructure ecosystems.

  5. Functional Connectivity Between Superior Parietal Lobule and Primary Visual Cortex "at Rest" Predicts Visual Search Efficiency.

    PubMed

    Bueichekú, Elisenda; Ventura-Campos, Noelia; Palomar-García, María-Ángeles; Miró-Padilla, Anna; Parcet, María-Antonia; Ávila, César

    2015-10-01

    Spatiotemporal activity that emerges spontaneously "at rest" has been proposed to reflect individual a priori biases in cognitive processing. This research focused on testing neurocognitive models of visual attention by studying the functional connectivity (FC) of the superior parietal lobule (SPL), given its central role in establishing priority maps during visual search tasks. Twenty-three human participants completed a functional magnetic resonance imaging session that featured a resting-state scan, followed by a visual search task based on the alphanumeric category effect. As expected, the behavioral results showed longer reaction times and more errors for the within-category (i.e., searching a target letter among letters) than the between-category search (i.e., searching a target letter among numbers). The within-category condition was related to greater activation of the superior and inferior parietal lobules, occipital cortex, inferior frontal cortex, dorsal anterior cingulate cortex, and the superior colliculus than the between-category search. The resting-state FC analysis of the SPL revealed a broad network that included connections with the inferotemporal cortex, dorsolateral prefrontal cortex, and dorsal frontal areas like the supplementary motor area and frontal eye field. Noteworthy, the regression analysis revealed that the more efficient participants in the visual search showed stronger FC between the SPL and areas of primary visual cortex (V1) related to the search task. We shed some light on how the SPL establishes a priority map of the environment during visual attention tasks and how FC is a valuable tool for assessing individual differences while performing cognitive tasks.

  6. FAR and NEAR Target Dynamic Visual Acuity: A Functional Assessment of Canal and Otolith Performance

    NASA Technical Reports Server (NTRS)

    Peters, Brian T.; Brady, Rachel A.; Landsness, Eric C.; Black, F. Owen; Bloomberg, Jacob J.

    2004-01-01

    Upon their return to earth, astronauts experience the effects of vestibular adaptation to microgravity. The postflight changes in vestibular information processing can affect postural and locomotor stability and may lead to oscillopsia during activities of daily living. However, it is likely that time spent in microgravity affects canal and otolith function differently. As a result, the isolated rotational stimuli used in traditional tests of canal function may fail to identify vestibular deficits after spaceflight. Also, the functional consequences of deficits that are identified often remain unknown. In a gaze control task, the relative contributions of the canal and otolith organs are modulated with viewing distance. The ability to stabilize gaze during a perturbation, on visual targets placed at different distances from the head may therefore provide independent insight into the function of this systems. Our goal was to develop a functional measure of gaze control that can also offer independent information about the function of the canal and otolith organs.

  7. Simple adaptive cubic spline interpolation of fluorescence decay functions

    NASA Astrophysics Data System (ADS)

    Kuśba, J.; Czuper, A.

    2007-05-01

    Simple method allowing for adaptive cubic spline interpolation of fluorescence decay functions is proposed. In the first step of the method, the interpolated function is integrated using the known adaptive algorithm based on Newton-Cotes quadratures. It is shown that, in this step, application of the Simpson's rule provides the smallest number of calls of the interpolated function. In the second step of the method, a typical cubic spline approximation is used to find values of the interpolated function between the points evaluated in the first step.

  8. How Visual Is the Visual Cortex? Comparing Connectional and Functional Fingerprints between Congenitally Blind and Sighted Individuals.

    PubMed

    Wang, Xiaoying; Peelen, Marius V; Han, Zaizhu; He, Chenxi; Caramazza, Alfonso; Bi, Yanchao

    2015-09-09

    Classical animal visual deprivation studies and human neuroimaging studies have shown that visual experience plays a critical role in shaping the functionality and connectivity of the visual cortex. Interestingly, recent studies have additionally reported circumscribed regions in the visual cortex in which functional selectivity was remarkably similar in individuals with and without visual experience. Here, by directly comparing resting-state and task-based fMRI data in congenitally blind and sighted human subjects, we obtained large-scale continuous maps of the degree to which connectional and functional "fingerprints" of ventral visual cortex depend on visual experience. We found a close agreement between connectional and functional maps, pointing to a strong interdependence of connectivity and function. Visual experience (or the absence thereof) had a pronounced effect on the resting-state connectivity and functional response profile of occipital cortex and the posterior lateral fusiform gyrus. By contrast, connectional and functional fingerprints in the anterior medial and posterior lateral parts of the ventral visual cortex were statistically indistinguishable between blind and sighted individuals. These results provide a large-scale mapping of the influence of visual experience on the development of both functional and connectivity properties of visual cortex, which serves as a basis for the formulation of new hypotheses regarding the functionality and plasticity of specific subregions. Significance statement: How is the functionality and connectivity of the visual cortex shaped by visual experience? By directly comparing resting-state and task-based fMRI data in congenitally blind and sighted subjects, we obtained large-scale continuous maps of the degree to which connectional and functional "fingerprints" of ventral visual cortex depend on visual experience. In addition to revealing regions that are strongly dependent on visual experience (early visual

  9. Psychometric Function Reconstruction from Adaptive Tracking Procedures

    DTIC Science & Technology

    1988-11-29

    reduced variability and length of the track can be shown by the use of the "sweat factor" defined by Taylor and Creelman (1967). This is a measure of...Psychophysics, 35, 385-392. Taylor, M. M., and Creelman , C. D. (1967). PEST: Efficient estimates on probability functions. Journal of the Acoustical Society of

  10. Influence of intraocular lens subsurface nanoglistenings on functional visual acuity

    PubMed Central

    Miyata, Kazunori; Hayashidera, Takeshi; Iida, Masaharu; Takada, Keita; Minami, Keiichiro; Oshika, Tetsuro

    2017-01-01

    To investigate the influence of intraocular lens subsurface nanoglistenings (SSNGs) on functional visual acuity (FVA), thirty-nine eyes of 29 patients were examined in this study. The SSNG group comprised 19 eyes of 14 patients (75.7± 5.4 years, mean ± standard deviation), and the control group comprised 20 eyes of 15 patients (73.6 ± 6.5 years). The SSNGs were diagnosed on the basis of the typical whitish IOL appearance upon slit-lamp examination and results of densitometry regarding surface light scattering using Scheimpflug images. The FVA measurement system (AS-28; Kowa, Aichi, Japan) was used to examine changes in continuous visual acuity (VA) over time, and visual function parameters such as FVA, visual maintenance ratio (VMR), maximum VA, minimum VA, standard deviation of VA, and number of blinks were assessed. The results were compared between the SSNG and control groups, and correlations of FVA parameters with the intensity of surface light scattering, time after surgery, and age were also evaluated. There were significant differences in VMR (P = 0.035) and standard deviation of VAs (P = 0.031) between the two groups, although no significant differences were found in baseline VA, FVA, maximum VA, minimum VA, and number of blinks. None of the FVA parameters showed any significant correlations with the intensity of surface light scattering, time after surgery, or age. There is a possibility that VA is unstable during a continuous gazing task in patients with SSNGs. PMID:28328997

  11. Real-time functional architecture of visual word recognition.

    PubMed

    Whiting, Caroline; Shtyrov, Yury; Marslen-Wilson, William

    2015-02-01

    Despite a century of research into visual word recognition, basic questions remain unresolved about the functional architecture of the process that maps visual inputs from orthographic analysis onto lexical form and meaning and about the units of analysis in terms of which these processes are conducted. Here we use magnetoencephalography, supported by a masked priming behavioral study, to address these questions using contrasting sets of simple (walk), complex (swimmer), and pseudo-complex (corner) forms. Early analyses of orthographic structure, detectable in bilateral posterior temporal regions within a 150-230 msec time frame, are shown to segment the visual input into linguistic substrings (words and morphemes) that trigger lexical access in left middle temporal locations from 300 msec. These are primarily feedforward processes and are not initially constrained by lexical-level variables. Lexical constraints become significant from 390 msec, in both simple and complex words, with increased processing of pseudowords and pseudo-complex forms. These results, consistent with morpho-orthographic models based on masked priming data, map out the real-time functional architecture of visual word recognition, establishing basic feedforward processing relationships between orthographic form, morphological structure, and lexical meaning.

  12. Dyspraxia, motor function and visual-motor integration in autism.

    PubMed

    Miller, M; Chukoskie, L; Zinni, M; Townsend, J; Trauner, D

    2014-08-01

    This project assessed dyspraxia in high-functioning school aged children with autism with a focus on Ideational Praxis. We examined the association of specific underlying motor function including eye movement with ideational dyspraxia (sequences of skilled movements) as well as the possible role of visual-motor integration in dyspraxia. We found that compared to IQ-, sex- and age-matched typically developing children, the children with autism performed significantly worse on: Ideational and Buccofacial praxis; a broad range of motor tests, including measures of simple motor skill, timing and accuracy of saccadic eye movements and motor coordination; and tests of visual-motor integration. Impairments in individual children with autism were heterogeneous in nature, although when we examined the praxis data as a function of a qualitative measure representing motor timing, we found that children with poor motor timing performed worse on all praxis categories and had slower and less accurate eye movements while those with regular timing performed as well as typical children on those same tasks. Our data provide evidence that both motor function and visual-motor integration contribute to dyspraxia. We suggest that dyspraxia in autism involves cerebellar mechanisms of movement control and the integration of these mechanisms with cortical networks implicated in praxis.

  13. Independent predictors of neuronal adaptation in human primary visual cortex measured with high-gamma activity.

    PubMed

    Matsuzaki, Naoyuki; Nagasawa, Tetsuro; Juhász, Csaba; Sood, Sandeep; Asano, Eishi

    2012-01-16

    Neuronal adaptation is defined as a reduced neural response to a repeated stimulus and can be demonstrated by reduced augmentation of event-related gamma activity. Several studies reported that variance in the degree of gamma augmentation could be explained by pre-stimulus low-frequency oscillations. Here, we measured the spatio-temporal characteristics of visually-driven amplitude modulations in human primary visual cortex using intracranial electrocorticography. We determined if inter-stimulus intervals or pre-stimulus oscillations independently predicted local neuronal adaptation measured with amplitude changes of high-gamma activity at 80-150 Hz. Participants were given repetitive photic stimuli with a flash duration of 20 μs in each block; the inter-stimulus interval was set constant within each block but different (0.2, 0.5, 1.0 or 2.0s) across blocks. Stimuli elicited augmentation of high-gamma activity in the occipital cortex at about 30 to 90 ms, and high-gamma augmentation was most prominent in the medial occipital region. High-gamma augmentation was subsequently followed by lingering beta augmentation at 20-30 Hz and high-gamma attenuation. Neuronal adaptation was demonstrated as a gradual reduction of high-gamma augmentation over trials. Multivariate analysis demonstrated that a larger number of prior stimuli, shorter inter-stimulus interval, and pre-stimulus high-gamma attenuation independently predicted a reduced high-gamma augmentation in a given trial, while pre-stimulus beta amplitude or delta phase had no significant predictive value. Association between pre-stimulus high-gamma attenuation and a reduced neural response suggests that high-gamma attenuation represents a refractory period. The local effects of pre-stimulus beta augmentation and delta phase on neuronal adaptation may be modest in primary visual cortex.

  14. Functional changes of the visual system of the damselfish Dascyllus marginatus along its bathymetric range.

    PubMed

    Brokovich, Eran; Ben-Ari, Tomer; Kark, Salit; Kiflawi, Moshe; Dishon, Gal; Iluz, David; Shashar, Nadav

    2010-11-02

    Shallow-water zooplanktivorous fish rely on their vision for foraging. In shallow water, feeding efficiency decreases in dim light and thus the fish cease foraging at crepuscular hours. Creatures living in the lower parts of their depth ranges are expected to be exposed to limited light levels for longer hours. However, observations of the zooplanktivore Dascyllus marginatus showed little change in foraging duration down to 40m deep. We asked whether the visual system's functionality changes with depth along the depth range of this damselfish; we examined eye and retina anatomy for changes in visual acuity and light sensitivity and used the optomotor response to test for spatial and temporal light summation. We found only minor changes in the anatomy of the eye that are not expected to affect visual sensitivity or acuity. However, behavioural experiments showed that the deeper water fish's test performance exceeded those of fish in shallow water under lower light levels. We found that deeper water fish responded to the optomotor test at lower light levels and also had more discriminating visual acuity in low light, which can increase their potential reactive distance. The plastic adaptive ability of the visual system to low light levels may explain the fish's ability to inhabit deeper reef habitats and thus expand their depth range limits.

  15. Adapting the iSNOBAL model for improved visualization in a GIS environment

    NASA Astrophysics Data System (ADS)

    Johansen, W. J.; Delparte, D.

    2014-12-01

    Snowmelt is a primary means of crucial water resources in much of the western United States. Researchers are developing models that estimate snowmelt to aid in water resource management. One such model is the image snowcover energy and mass balance (iSNOBAL) model. It uses input climate grids to simulate the development and melting of snowpack in mountainous regions. This study looks at applying this model to the Reynolds Creek Experimental Watershed in southwestern Idaho, utilizing novel approaches incorporating geographic information systems (GIS). To improve visualization of the iSNOBAL model, we have adapted it to run in a GIS environment. This type of environment is suited to both the input grid creation and the visualization of results. The data used for input grid creation can be stored locally or on a web-server. Kriging interpolation embedded within Python scripts are used to create air temperature, soil temperature, humidity, and precipitation grids, while built-in GIS and existing tools are used to create solar radiation and wind grids. Additional Python scripting is then used to perform model calculations. The final product is a user-friendly and accessible version of the iSNOBAL model, including the ability to easily visualize and interact with model results, all within a web- or desktop-based GIS environment. This environment allows for interactive manipulation of model parameters and visualization of the resulting input grids for the model calculations. Future work is moving towards adapting the model further for use in a 3D gaming engine for improved visualization and interaction.

  16. Brain networks for visual creativity: a functional connectivity study of planning a visual artwork

    PubMed Central

    De Pisapia, Nicola; Bacci, Francesca; Parrott, Danielle; Melcher, David

    2016-01-01

    Throughout recorded history, and across cultures, humans have made visual art. In recent years, the neural bases of creativity, including artistic creativity, have become a topic of interest. In this study we investigated the neural bases of the visual creative process with both professional artists and a group of control participants. We tested the idea that creativity (planning an artwork) would influence the functional connectivity between regions involved in the default mode network (DMN), implicated in divergent thinking and generating novel ideas, and the executive control network (EN), implicated in evaluating and selecting ideas. We measured functional connectivity with functional Magnetic Resonance Imaging (fMRI) during three different conditions: rest, visual imagery of the alphabet and planning an artwork to be executed immediately after the scanning session. Consistent with our hypothesis, we found stronger connectivity between areas of the DMN and EN during the creative task, and this difference was enhanced in professional artists. These findings suggest that creativity involves an expert balance of two brain networks typically viewed as being in opposition. PMID:27991592

  17. GPView: A program for wave function analysis and visualization.

    PubMed

    Shi, Tian; Wang, Ping

    2016-11-01

    In this manuscript, we will introduce a recently developed program GPView, which can be used for wave function analysis and visualization. The wave function analysis module can calculate and generate 3D cubes for various types of molecular orbitals and electron density of electronic excited states, such as natural orbitals, natural transition orbitals, natural difference orbitals, hole-particle density, detachment-attachment density and transition density. The visualization module of GPView can display molecular and electronic (iso-surfaces) structures. It is also able to animate single trajectories of molecular dynamics and non-adiabatic excited state molecular dynamics using the data stored in existing files. There are also other utilities to extract and process the output of quantum chemistry calculations. The GPView provides full graphic user interface (GUI), so it very easy to use. It is available from website http://life-tp.com/gpview.

  18. Visual feedback of the moving arm allows complete adaptation of pointing movements to centrifugal and Coriolis forces in human subjects.

    PubMed

    Bourdin, C; Gauthier, G; Blouin, J; Vercher, J L

    2001-03-23

    A classical visuo-manual adaptation protocol carried out on a rotating platform was used to test the ability of subjects to adapt to centrifugal and Coriolis forces when visual feedback of the arm is manipulated. Three main results emerge: (a) an early modification of the initial trajectory of the movements takes place even without visual feedback of the arm; (b) despite the change in the initial trajectory, the new external force decreases the accuracy of the pointing movements when vision is precluded; (c) a visual adaptive phase allows complete adaptation of the pointing movements performed in a modified gravitoinertial field. Therefore vision would be essential for subjects to completely adapt to centrifugal and Coriolis forces. However, other sensory signals (i.e. vestibular and proprioceptive) may constitute the basis for early but partial correction of the pointing movements.

  19. Executive functions and adaptive functioning in young adult attention-deficit/hyperactivity disorder.

    PubMed

    Stavro, Gillian M; Ettenhofer, Mark L; Nigg, Joel T

    2007-03-01

    Attention-deficit/hyperactivity disorder (ADHD) is associated with impairments in occupational, social, and educational functioning in adults. This study examined relations of adaptive impairment to ADHD symptom domains (inattentive-disorganized and hyperactive-impulsive) and to deficits in executive functioning (EF) in 195 well-characterized adults (105 ADHD, 90 non-ADHD, between ages 18 and 37). Participants completed a battery of EF measures as well as assessments of adaptive functioning. Confirmatory factor analyses were used to validate latent factors for adaptive functioning and EF. In a measurement model, weaker EF was associated with poorer adaptive functioning (r = -.30). When multi-informant composite variables for current inattentive-disorganized and hyperactive-impulsive ADHD symptoms were included in the structural model, EF no longer predicted adaptive functioning. While both symptom composites were similarly related to EF (inattentive-disorganized r = .36; hyperactive-impulsive r = .29), inattentive-disorganized symptoms accounted for more variance in adaptive functioning (67.2% vs. 3.6%). Furthermore, for retrospectively reported childhood symptoms of ADHD, only the inattentive-disorganized symptom domain was related to EF or adaptive impairment. These results suggest that, in adults with ADHD, inattentive-disorganized symptoms may be the primary contributor to key aspects of poorer adaptive function and may be the behavioral path through which EF deficits lead to adaptive impairment.

  20. Binocular adaptive optics visual simulator: understanding the impact of aberrations on actual vision

    NASA Astrophysics Data System (ADS)

    Fernández, Enrique J.; Prieto, Pedro M.; Artal, Pablo

    2010-02-01

    A novel adaptive optics system is presented for the study of vision. The apparatus is capable for binocular operation. The binocular adaptive optics visual simulator permits measuring and manipulating ocular aberrations of the two eyes simultaneously. Aberrations can be corrected, or modified, while the subject performs visual testing under binocular vision. One of the most remarkable features of the apparatus consists on the use of a single correcting device, and a single wavefront sensor (Hartmann-Shack). Both the operation and the total cost of the instrument largely benefit from this attribute. The correcting device is a liquid-crystal-on-silicon (LCOS) spatial light modulator. The basic performance of the visual simulator consists in the simultaneous projection of the two eyes' pupils onto both the corrector and sensor. Examples of the potential of the apparatus for the study of the impact of the aberrations under binocular vision are presented. Measurements of contrast sensitivity with modified combinations of spherical aberration through focus are shown. Special attention was paid on the simulation of monovision, where one eye is corrected for far vision while the other is focused at near distance. The results suggest complex binocular interactions. The apparatus can be dedicated to the better understanding of the vision mechanism, which might have an important impact in developing new protocols and treatments for presbyopia. The technique and the instrument might contribute to search optimized ophthalmic corrections.

  1. Filtering Based Adaptive Visual Odometry Sensor Framework Robust to Blurred Images.

    PubMed

    Zhao, Haiying; Liu, Yong; Xie, Xiaojia; Liao, Yiyi; Liu, Xixi

    2016-07-05

    Visual odometry (VO) estimation from blurred image is a challenging problem in practical robot applications, and the blurred images will severely reduce the estimation accuracy of the VO. In this paper, we address the problem of visual odometry estimation from blurred images, and present an adaptive visual odometry estimation framework robust to blurred images. Our approach employs an objective measure of images, named small image gradient distribution (SIGD), to evaluate the blurring degree of the image, then an adaptive blurred image classification algorithm is proposed to recognize the blurred images, finally we propose an anti-blurred key-frame selection algorithm to enable the VO robust to blurred images. We also carried out varied comparable experiments to evaluate the performance of the VO algorithms with our anti-blur framework under varied blurred images, and the experimental results show that our approach can achieve superior performance comparing to the state-of-the-art methods under the condition with blurred images while not increasing too much computation cost to the original VO algorithms.

  2. Autonomous robotic capture of non-cooperative target by adaptive extended Kalman filter based visual servo

    NASA Astrophysics Data System (ADS)

    Dong, Gangqi; Zhu, Zheng H.

    2016-05-01

    This paper presents a real-time, vision-based algorithm for the pose and motion estimation of non-cooperative targets and its application in visual servo robotic manipulator to perform autonomous capture. A hybrid approach of adaptive extended Kalman filter and photogrammetry is developed for the real-time pose and motion estimation of non-cooperative targets. Based on the pose and motion estimates, the desired pose and trajectory of end-effector is defined and the corresponding desired joint angles of the robotic manipulator are derived by inverse kinematics. A close-loop visual servo control scheme is then developed for the robotic manipulator to track, approach and capture the target. Validating experiments are designed and performed on a custom-built six degrees of freedom robotic manipulator with an eye-in-hand configuration. The experimental results demonstrate the feasibility, effectiveness and robustness of the proposed adaptive extended Kalman filter enabled pose and motion estimation and visual servo strategy.

  3. Robust Visual Knowledge Transfer via Extreme Learning Machine Based Domain Adaptation.

    PubMed

    Zhang, Lei; Zhang, David

    2016-08-10

    We address the problem of visual knowledge adaptation by leveraging labeled patterns from source domain and a very limited number of labeled instances in target domain to learn a robust classifier for visual categorization. This paper proposes a new extreme learning machine based cross-domain network learning framework, that is called Extreme Learning Machine (ELM) based Domain Adaptation (EDA). It allows us to learn a category transformation and an ELM classifier with random projection by minimizing the -norm of the network output weights and the learning error simultaneously. The unlabeled target data, as useful knowledge, is also integrated as a fidelity term to guarantee the stability during cross domain learning. It minimizes the matching error between the learned classifier and a base classifier, such that many existing classifiers can be readily incorporated as base classifiers. The network output weights cannot only be analytically determined, but also transferrable. Additionally, a manifold regularization with Laplacian graph is incorporated, such that it is beneficial to semi-supervised learning. Extensively, we also propose a model of multiple views, referred as MvEDA. Experiments on benchmark visual datasets for video event recognition and object recognition, demonstrate that our EDA methods outperform existing cross-domain learning methods.

  4. The Diabetes Visual Function Supplement Study (DiVFuSS)

    PubMed Central

    Chous, A Paul; Richer, Stuart P; Gerson, Jeffry D; Kowluru, Renu A

    2016-01-01

    Background Diabetes is known to affect visual function before onset of retinopathy (diabetic retinopathy (DR)). Protection of visual function may signal disruption of mechanisms underlying DR. Methods This was a 6-month randomised, controlled clinical trial of patients with type 1 and type 2 diabetes with no retinopathy or mild to moderate non-proliferative retinopathy assigned to twice daily consumption of placebo or a novel, multi-component formula containing xanthophyll pigments, antioxidants and selected botanical extracts. Measurement of contrast sensitivity, macular pigment optical density, colour discrimination, 5-2 macular threshold perimetry, Diabetic Peripheral Neuropathy Symptoms, foveal and retinal nerve fibre layer thickness, glycohaemoglobin (HbA1c), serum lipids, 25-OH-vitamin D, tumour necrosis factor α (TNF-a) and high-sensitivity C reactive protein (hsCRP) were taken at baseline and 6 months. Outcomes were assessed by differences between and within groups at baseline and at study conclusion using meand ± SDs and t tests (p<0.05) for continuous variables. Results There were no significant intergroup differences at baseline. At 6 months, subjects on active supplement compared with placebo had significantly better visual function on all measures (p values ranging from 0.008 to <0.0001), significant improvements in most serum lipids (p values ranging from 0.01 to 0.0004), hsCRP (p=0.01) and diabetic peripheral neuropathy (Fisher's exact test, p=0.0024) No significant changes in retinal thickness, HbA1c, total cholesterol or TNF-α were found between the groups. Conclusions This study provides strong evidence of clinically meaningful improvements in visual function, hsCRP and peripheral neuropathy in patients with diabetes, both with and without retinopathy, and without affecting glycaemic control. Trial registration number www.ClinicalTrials.gov Identifier: NCT01646047 PMID:26089210

  5. Testing Changes in Visual Function Due to Orbital Environment

    DTIC Science & Technology

    1984-01-01

    describes a device submitted by the AF Aerospace Medical Research Laboratory for inclusion aboard several NASA Shuttle Flights, in an attempt to detect...Duntley Tests ROCET P0BL 4 VISUAL FUNCTION TESTER [ODEL I (VFT-1) 5 Description Usage Critical Fusion Frequency Stereopsis Snellen Acuity Resolution...self-contained, draw no power from the Shuttle, and must meet stringent NASA technical, safety and acceptance standards. This report describes the

  6. Characterizing contrast adaptation in a population of cat primary visual cortical neurons using Fisher information.

    PubMed

    Durant, Szonya; Clifford, Colin W G; Crowder, Nathan A; Price, Nicholas S C; Ibbotson, Michael R

    2007-06-01

    When cat V1/V2 cells are adapted to contrast at their optimal orientation, a reduction in gain and/or a shift in the contrast response function is found. We investigated how these factors combine at the population level to affect the accuracy for detecting variations in contrast. Using the contrast response function parameters from a physiologically measured population, we model the population accuracy (using Fisher information) for contrast discrimination. Adaptation at 16%, 32%, and 100% contrast causes a shift in peak accuracy. Despite an overall drop in firing rate over the whole population, accuracy is enhanced around the adapted contrast and at higher contrasts, leading to greater efficiency of contrast coding at these levels. The estimated contrast discrimination threshold curve becomes elevated and shifted toward higher contrasts after adaptation, as has been found previously in human psychophysical experiments.

  7. Improving pattern discovery and visualization of SAGE data through poisson-based self-adaptive neural networks.

    PubMed

    Zheng, Huiru; Wang, Haiying; Azuaje, Francisco

    2008-07-01

    Serial analysis of gene expression (SAGE) allows a detailed, simultaneous analysis of thousands of genes without the need for prior, complete gene sequence information. However, due to its inherent complexity and the lack of complete structural and function knowledge, mining vast collections of SAGE data to extract useful knowledge poses great challenges to traditional analytical techniques. Moreover, SAGE data are characterized by a specific statistical model that has not been incorporated into traditional data analysis techniques. The analysis of SAGE data requires advanced, intelligent computational techniques, which consider the underlying biology and the statistical nature of SAGE data. By addressing the statistical properties demonstrated by SAGE data, this paper presents a new self-adaptive neural network, Poisson-based growing self-organizing map (PGSOM), which implements novel weight adaptation and neuron growing strategies. An empirical study of key dynamic mechanisms of PGSOM is presented. It was tested on three datasets, including synthetic and experimental SAGE data. The results indicate that, in comparison to traditional techniques, the PGSOM offers significant advantages in the context of pattern discovery and visualization in SAGE data. The pattern discovery and visualization platform discussed in this paper can be applied to other problem domains where the data are better approximated by a Poisson distribution.

  8. Functional specialization in rat occipital and temporal visual cortex

    PubMed Central

    Vermaercke, Ben; Gerich, Florian J.; Ytebrouck, Ellen; Arckens, Lutgarde; Van den Bergh, Gert

    2014-01-01

    Recent studies have revealed a surprising degree of functional specialization in rodent visual cortex. Anatomically, suggestions have been made about the existence of hierarchical pathways with similarities to the ventral and dorsal pathways in primates. Here we aimed to characterize some important functional properties in part of the supposed “ventral” pathway in rats. We investigated the functional properties along a progression of five visual areas in awake rats, from primary visual cortex (V1) over lateromedial (LM), latero-intermediate (LI), and laterolateral (LL) areas up to the newly found lateral occipito-temporal cortex (TO). Response latency increased >20 ms from areas V1/LM/LI to areas LL and TO. Orientation and direction selectivity for the used grating patterns increased gradually from V1 to TO. Overall responsiveness and selectivity to shape stimuli decreased from V1 to TO and was increasingly dependent upon shape motion. Neural similarity for shapes could be accounted for by a simple computational model in V1, but not in the other areas. Across areas, we find a gradual change in which stimulus pairs are most discriminable. Finally, tolerance to position changes increased toward TO. These findings provide unique information about possible commonalities and differences between rodents and primates in hierarchical cortical processing. PMID:24990566

  9. The Use of Dynamic Visual Acuity as a Functional Test of Gaze Stabilization Following Space Flight

    NASA Technical Reports Server (NTRS)

    Peters, B. T.; Mulavara, A. P.; Brady, R.; Miller, C. A.; Richards, J. T.; Warren, L. E.; Cohen, H. S.; Bloomberg, J. J.

    2006-01-01

    After prolonged exposure to a given gravitational environment the transition to another is accompanied by adaptations in the sensorimotor subsystems, including the vestibular system. Variation in the adaptation time course of these subsystems, and the functional redundancies that exist between them make it difficult to accurately assess the functional capacity and physical limitations of astro/cosmonauts using tests on individual subsystems. While isolated tests of subsystem performance may be the only means to address where interventions are required, direct measures of performance may be more suitable for assessing the operational consequences of incomplete adaptation to changes in the gravitational environment. A test of dynamic visual acuity (DVA) is currently being used in the JSC Neurosciences Laboratory as part of a series of measures to assess the efficacy of a countermeasure to mitigate postflight locomotor dysfunction. In the current protocol, subjects visual acuity is determined using Landolt ring optotypes presented sequentially on a computer display. Visual acuity assessments are made both while standing and while walking at 1.8 m/s on a motorized treadmill. The use of a psychophysical threshold detection algorithm reduces the required number of optotype presentations and the results can be presented immediately after the test. The difference between the walking and standing acuity measures provides a metric of the change in the subject s ability to maintain gaze fixation on the visual target while walking. This functional consequence is observable regardless of the underlying subsystem most responsible for the change. Data from 15 cosmo/astronauts have been collected following long-duration (approx. 6 months) stays in space using a visual target viewing distance of 4.0 meters. An investigation of the group mean shows a change in DVA soon after the flight that asymptotes back to baseline approximately one week following their return to earth. The

  10. Color Functionality Used in Visual Display for Occupational and Environmental Safety and Managing Color Vision Deficiency.

    PubMed

    Ochiai, Nobuhisa; Kondo, Hiroyuki

    2017-01-01

    The effects of color perception are utilized in visual displays for the purpose of safety in the workplace and in daily life. These effects, generally known as color functionality, are divided into four classifications: visibility, legibility, conspicuity and discriminability. This article focuses on the relationship between the color functionality of color schemes used in visual displays for occupational and environmental safety and color vision deficiency (particularly congenital red-green color deficiency), a critical issue in ophthalmology, and examines the effects of color functionality on the perception of the color red in individuals with protan defects. Due to abrupt system reforms, current Japanese clinical ophthalmology finds itself in a situation where it is insufficiently prepared to handle congenital red-green color deficiencies. Indeed, occupational problems caused by color vision deficiencies have been almost completely neglected, and are an occupational safety and health concern that will need to be solved in the future. This report will present the guidelines for the color vision testing established by the British Health and Safety Executive (HSE), a pioneering example of a model meant to solve these problems. Issues relating to the creation of guidelines adapted to Japanese clinical ophthalmology will also be examined, and we will discuss ways to utilize color functionality used in visual displays for occupational and environmental safety to help manage color vision deficiency.

  11. Differential functioning of Bender Visual-Motor Gestalt Test items.

    PubMed

    Sisto, Fermino Fernandes; Dos Santos, Acácia Aparecida Angeli; Noronha, Ana Paula Porto

    2010-02-01

    Differential Item Functioning (DIF) refers to items that do not function the same way for comparable members of different groups. The present study focuses on analyzing and classifying sex-related differential item functioning in the Bender Visual-Motor Gestalt Test. Subjects were 1,052 children attending public schools (513 boys, 539 girls, ages 6-10 years). The protocols were scored using the Bender Graduated Scoring System, which evaluates only the distortion criterion using the Rasch logistic response model. The scoring system fit the Rasch model, although two items were found to be biased by sex. When analyzing differential functioning of items for boys and girls separately, the number of differentially functioning items was equal.

  12. NIFTY (NeuroImaging Functional Toolkit): an interactive program for functional MRI data processing and visualization

    NASA Astrophysics Data System (ADS)

    Arnholt, Jeff C.; Hanson, Dennis P.; Robb, Richard A.

    1995-05-01

    NIFTY (NeuroImaging Functional Toolkit) is a tool designed to perform quantitative analysis and visualization of neurofunctional magnetic resonance image (fMRI) data sets. NIFTY is an OSF/Motif application which utilizes the AVW (a visualization workshop) imaging library developed in our laboratory and includes algorithms for robust image registration, statistical analysis, and mapping of neurofunctional data sets. Anisotropic diffusion routines can be used to enhance the signal-to-noise- ratio of these images. Tools capable of histogram equalization, thresholding, volume rendering, atlas matching, and a large number of other functions can then be used to visualize the data. NIFTY's development will offer a robust and flexible system of essential functions integrated into an interactive, graphically-oriented program, allowing neuroscientists the means by which to process, visualize, and interpret their data.

  13. The research and application of visual saliency and adaptive support vector machine in target tracking field.

    PubMed

    Chen, Yuantao; Xu, Weihong; Kuang, Fangjun; Gao, Shangbing

    2013-01-01

    The efficient target tracking algorithm researches have become current research focus of intelligent robots. The main problems of target tracking process in mobile robot face environmental uncertainty. They are very difficult to estimate the target states, illumination change, target shape changes, complex backgrounds, and other factors and all affect the occlusion in tracking robustness. To further improve the target tracking's accuracy and reliability, we present a novel target tracking algorithm to use visual saliency and adaptive support vector machine (ASVM). Furthermore, the paper's algorithm has been based on the mixture saliency of image features. These features include color, brightness, and sport feature. The execution process used visual saliency features and those common characteristics have been expressed as the target's saliency. Numerous experiments demonstrate the effectiveness and timeliness of the proposed target tracking algorithm in video sequences where the target objects undergo large changes in pose, scale, and illumination.

  14. The change probability effect: incidental learning, adaptability, and shared visual working memory resources.

    PubMed

    van Lamsweerde, Amanda E; Beck, Melissa R

    2011-12-01

    Statistical properties in the visual environment can be used to improve performance on visual working memory (VWM) tasks. The current study examined the ability to incidentally learn that a change is more likely to occur to a particular feature dimension (shape, color, or location) and use this information to improve change detection performance for that dimension (the change probability effect). Participants completed a change detection task in which one change type was more probable than others. Change probability effects were found for color and shape changes, but not location changes, and intentional strategies did not improve the effect. Furthermore, the change probability effect developed and adapted to new probability information quickly. Finally, in some conditions, an improvement in change detection performance for a probable change led to an impairment in change detection for improbable changes.

  15. Designing Adaptive, Diagnostic Math Assessments for Individuals with and without Visual Disabilities. Research Report. ETS RR-06-01

    ERIC Educational Resources Information Center

    Shute, Valerie J.; Graf, Edith Aurora; Hansen, Eric G.

    2006-01-01

    This report summarizes the design and development of an adaptive e-learning prototype for middle school mathematics for use with both sighted and visually disabled students. Adaptation refers to the system's ability to adjust itself to suit particular characteristics of the learner. The main parts of the report describe the system's theoretical…

  16. Adaptive bandwidth measurements of importance functions for speech intelligibility prediction.

    PubMed

    Whitmal, Nathaniel A; DeRoy, Kristina

    2011-12-01

    The Articulation Index (AI) and Speech Intelligibility Index (SII) predict intelligibility scores from measurements of speech and hearing parameters. One component in the prediction is the "importance function," a weighting function that characterizes contributions of particular spectral regions of speech to speech intelligibility. Previous work with SII predictions for hearing-impaired subjects suggests that prediction accuracy might improve if importance functions for individual subjects were available. Unfortunately, previous importance function measurements have required extensive intelligibility testing with groups of subjects, using speech processed by various fixed-bandwidth low-pass and high-pass filters. A more efficient approach appropriate to individual subjects is desired. The purpose of this study was to evaluate the feasibility of measuring importance functions for individual subjects with adaptive-bandwidth filters. In two experiments, ten subjects with normal-hearing listened to vowel-consonant-vowel (VCV) nonsense words processed by low-pass and high-pass filters whose bandwidths were varied adaptively to produce specified performance levels in accordance with the transformed up-down rules of Levitt [(1971). J. Acoust. Soc. Am. 49, 467-477]. Local linear psychometric functions were fit to resulting data and used to generate an importance function for VCV words. Results indicate that the adaptive method is reliable and efficient, and produces importance function data consistent with that of the corresponding AI/SII importance function.

  17. Functional Literacy for Students with Visual Impairments and Significant Cognitive Disabilities: The Perspective of Teachers of Students with Visual Impairments

    ERIC Educational Resources Information Center

    Zebehazy, Kim T.

    2014-01-01

    This study reports opinions and practices of teachers of students with visual impairments (TSVIs) in 34 states regarding functional literacy for students with visual impairments (VIs) and significant cognitive disabilities (SCDs). The survey asked TSVIs to select a definition of functional literacy, indicate agreement with a series of literacy…

  18. Image-adapted visually weighted quantization matrices for digital image compression

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B. (Inventor)

    1994-01-01

    A method for performing image compression that eliminates redundant and invisible image components is presented. The image compression uses a Discrete Cosine Transform (DCT) and each DCT coefficient yielded by the transform is quantized by an entry in a quantization matrix which determines the perceived image quality and the bit rate of the image being compressed. The present invention adapts or customizes the quantization matrix to the image being compressed. The quantization matrix comprises visual masking by luminance and contrast techniques and by an error pooling technique all resulting in a minimum perceptual error for any given bit rate, or minimum bit rate for a given perceptual error.

  19. Balance Functional Assessment in People with Visual Impairment.

    PubMed

    Rutkowska, Izabela; Bednarczuk, Grzegorz; Molik, Bartosz; Morgulec-Adamowicz, Natalia; Marszałek, Jolanta; Kaźmierska-Kowalewska, Kalina; Koc, Krzysztof

    2015-11-22

    The aims of this study were twofold: to assess the level of balance of people with visual impairment against the BOT-2 standard scores for the able-bodied, and to identify in which trials subjects had the greatest difficulties in maintaining balance with respect to the degree of vision loss and age categories. One hundred twenty-seven subjects with visual impairment aged 6-16 years, participated in the study (68 girls and 59 boys). The division for partially sighted people (61) and the blind (66) was made according to the WHO classification. Functional balance assessment was made using a balance subtest from the Bruininks-Oseretsky test. Significant relationships were noticed between age and the level of balance (χ2 = 8.35 p <0,05), as well as between the degree of vision loss and the level of balance (χ2 = 24.53 p <0,001). The level of balance of almost all blind subjects was below (20%) or well-below (60%) the average for the able-bodied. The subjects' ability to maintain balance was not dependent on gender and was associated primarily with the degree of visual impairment and age. Partially sighted people had better balance than the blind and the decrease in visual acuity resulted in reduction of balance skills. The lowest level of balance was observed in blind students aged 7-11 years. Elaborating physical fitness improvement programs for children and adolescents with visual impairment, diversity of age, the degree of vision loss and limitations of ablility to maintain balance should be taken into account.

  20. Binocular adaptive optics vision analyzer with full control over the complex pupil functions.

    PubMed

    Schwarz, Christina; Prieto, Pedro M; Fernández, Enrique J; Artal, Pablo

    2011-12-15

    We present a binocular adaptive optics vision analyzer fully capable of controlling both amplitude and phase of the two complex pupil functions in each eye of the subject. A special feature of the instrument is its comparatively simple setup. A single reflective liquid crystal on silicon spatial light modulator working in pure phase modulation generates the phase profiles for both pupils simultaneously. In addition, another liquid crystal spatial light modulator working in transmission operates in pure intensity modulation to produce a large variety of pupil masks for each eye. Subjects perform visual tasks through any predefined variations of the complex pupil function for both eyes. As an example of the system efficiency, we recorded images of the stimuli through the system as they were projected at the subject's retina. This instrument proves to be extremely versatile for designing and testing novel ophthalmic elements and simulating visual outcomes, as well as for further research of binocular vision.

  1. Improving nonlinear modeling capabilities of functional link adaptive filters.

    PubMed

    Comminiello, Danilo; Scarpiniti, Michele; Scardapane, Simone; Parisi, Raffaele; Uncini, Aurelio

    2015-09-01

    The functional link adaptive filter (FLAF) represents an effective solution for online nonlinear modeling problems. In this paper, we take into account a FLAF-based architecture, which separates the adaptation of linear and nonlinear elements, and we focus on the nonlinear branch to improve the modeling performance. In particular, we propose a new model that involves an adaptive combination of filters downstream of the nonlinear expansion. Such combination leads to a cooperative behavior of the whole architecture, thus yielding a performance improvement, particularly in the presence of strong nonlinearities. An advanced architecture is also proposed involving the adaptive combination of multiple filters on the nonlinear branch. The proposed models are assessed in different nonlinear modeling problems, in which their effectiveness and capabilities are shown.

  2. VAP-CAP: A Procedure to Assess the Visual Functioning of Young Visually Impaired Children.

    ERIC Educational Resources Information Center

    Blanksby, D. C.; Langford, P. E.

    1993-01-01

    This article describes a visual assessment procedure (VAP) which evaluates capacity, attention, and processing (CAP) of infants and preschool children with visual impairments. The two-level battery considers, first, visual capacity and basic visual attention and, second, visual perceptual and cognitive abilities. A theoretical analysis of the…

  3. The functional basis of adaptive evolution in chemostats.

    PubMed

    Gresham, David; Hong, Jungeui

    2015-01-01

    Two of the central problems in biology are determining the molecular basis of adaptive evolution and understanding how cells regulate their growth. The chemostat is a device for culturing cells that provides great utility in tackling both of these problems: it enables precise control of the selective pressure under which organisms evolve and it facilitates experimental control of cell growth rate. The aim of this review is to synthesize results from studies of the functional basis of adaptive evolution in long-term chemostat selections using Escherichia coli and Saccharomyces cerevisiae. We describe the principle of the chemostat, provide a summary of studies of experimental evolution in chemostats, and use these studies to assess our current understanding of selection in the chemostat. Functional studies of adaptive evolution in chemostats provide a unique means of interrogating the genetic networks that control cell growth, which complements functional genomic approaches and quantitative trait loci (QTL) mapping in natural populations. An integrated approach to the study of adaptive evolution that accounts for both molecular function and evolutionary processes is critical to advancing our understanding of evolution. By renewing efforts to integrate these two research programs, experimental evolution in chemostats is ideally suited to extending the functional synthesis to the study of genetic networks.

  4. The functional basis of adaptive evolution in chemostats

    PubMed Central

    Gresham, David; Hong, Jungeui

    2014-01-01

    Two of the central problems in biology are determining the molecular basis of adaptive evolution and understanding how cells regulate their growth. The chemostat is a device for culturing cells that provides great utility in tackling both of these problems: it enables precise control of the selective pressure under which organisms evolve and it facilitates experimental control of cell growth rate. The aim of this review is to synthesize results from studies of the functional basis of adaptive evolution in long-term chemostat selections using Escherichia coli and Saccharomyces cerevisiae. We describe the principle of the chemostat, provide a summary of studies of experimental evolution in chemostats, and use these studies to assess our current understanding of selection in the chemostat. Functional studies of adaptive evolution in chemostats provide a unique means of interrogating the genetic networks that control cell growth, which complements functional genomic approaches and quantitative trait loci (QTL) mapping in natural populations. An integrated approach to the study of adaptive evolution that accounts for both molecular function and evolutionary processes is critical to advancing our understanding of evolution. By renewing efforts to integrate these two research programs, experimental evolution in chemostats is ideally suited to extending the functional synthesis to the study of genetic networks. PMID:25098268

  5. Perceptual learning modifies the functional specializations of visual cortical areas.

    PubMed

    Chen, Nihong; Cai, Peng; Zhou, Tiangang; Thompson, Benjamin; Fang, Fang

    2016-05-17

    Training can improve performance of perceptual tasks. This phenomenon, known as perceptual learning, is strongest for the trained task and stimulus, leading to a widely accepted assumption that the associated neuronal plasticity is restricted to brain circuits that mediate performance of the trained task. Nevertheless, learning does transfer to other tasks and stimuli, implying the presence of more widespread plasticity. Here, we trained human subjects to discriminate the direction of coherent motion stimuli. The behavioral learning effect substantially transferred to noisy motion stimuli. We used transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms underlying the transfer of learning. The TMS experiment revealed dissociable, causal contributions of V3A (one of the visual areas in the extrastriate visual cortex) and MT+ (middle temporal/medial superior temporal cortex) to coherent and noisy motion processing. Surprisingly, the contribution of MT+ to noisy motion processing was replaced by V3A after perceptual training. The fMRI experiment complemented and corroborated the TMS finding. Multivariate pattern analysis showed that, before training, among visual cortical areas, coherent and noisy motion was decoded most accurately in V3A and MT+, respectively. After training, both kinds of motion were decoded most accurately in V3A. Our findings demonstrate that the effects of perceptual learning extend far beyond the retuning of specific neural populations for the trained stimuli. Learning could dramatically modify the inherent functional specializations of visual cortical areas and dynamically reweight their contributions to perceptual decisions based on their representational qualities. These neural changes might serve as the neural substrate for the transfer of perceptual learning.

  6. Perceptual learning modifies the functional specializations of visual cortical areas

    PubMed Central

    Chen, Nihong; Cai, Peng; Zhou, Tiangang; Thompson, Benjamin; Fang, Fang

    2016-01-01

    Training can improve performance of perceptual tasks. This phenomenon, known as perceptual learning, is strongest for the trained task and stimulus, leading to a widely accepted assumption that the associated neuronal plasticity is restricted to brain circuits that mediate performance of the trained task. Nevertheless, learning does transfer to other tasks and stimuli, implying the presence of more widespread plasticity. Here, we trained human subjects to discriminate the direction of coherent motion stimuli. The behavioral learning effect substantially transferred to noisy motion stimuli. We used transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms underlying the transfer of learning. The TMS experiment revealed dissociable, causal contributions of V3A (one of the visual areas in the extrastriate visual cortex) and MT+ (middle temporal/medial superior temporal cortex) to coherent and noisy motion processing. Surprisingly, the contribution of MT+ to noisy motion processing was replaced by V3A after perceptual training. The fMRI experiment complemented and corroborated the TMS finding. Multivariate pattern analysis showed that, before training, among visual cortical areas, coherent and noisy motion was decoded most accurately in V3A and MT+, respectively. After training, both kinds of motion were decoded most accurately in V3A. Our findings demonstrate that the effects of perceptual learning extend far beyond the retuning of specific neural populations for the trained stimuli. Learning could dramatically modify the inherent functional specializations of visual cortical areas and dynamically reweight their contributions to perceptual decisions based on their representational qualities. These neural changes might serve as the neural substrate for the transfer of perceptual learning. PMID:27051066

  7. Dynamic Visual Acuity: a Functionally Relevant Research Tool

    NASA Technical Reports Server (NTRS)

    Peters, Brian T.; Brady, Rachel A.; Miller, Chris A.; Mulavara, Ajitkumar P.; Wood, Scott J.; Cohen, Helen S.; Bloomberg, Jacob J.

    2010-01-01

    Coordinated movements between the eyes and head are required to maintain a stable retinal image during head and body motion. The vestibulo-ocular reflex (VOR) plays a significant role in this gaze control system that functions well for most daily activities. However, certain environmental conditions or interruptions in normal VOR function can lead to inadequate ocular compensation, resulting in oscillopsia, or blurred vision. It is therefore possible to use acuity to determine when the environmental conditions, VOR function, or the combination of the two is not conductive for maintaining clear vision. Over several years we have designed and tested several tests of dynamic visual acuity (DVA). Early tests used the difference between standing and walking acuity to assess decrements in the gaze stabilization system after spaceflight. Supporting ground-based studies measured the responses from patients with bilateral vestibular dysfunction and explored the effects of visual target viewing distance and gait cycle events on walking acuity. Results from these studies show that DVA is affected by spaceflight, is degraded in patients with vestibular dysfunction, changes with target distance, and is not consistent across the gait cycle. We have recently expanded our research to include studies in which seated subjects are translated or rotated passively. Preliminary results from this work indicate that gaze stabilization ability may differ between similar active and passive conditions, may change with age, and can be affected by the location of the visual target with respect to the axis of motion. Use of DVA as a diagnostic tool is becoming more popular but the functional nature of the acuity outcome measure also makes it ideal for identifying conditions that could lead to degraded vision. By doing so, steps can be taken to alter the problematic environments to improve the man-machine interface and optimize performance.

  8. Modeling Visual Symptoms and Visual Skills to Measure Functional Binocular Vision

    NASA Astrophysics Data System (ADS)

    Powers, M. K.; Fisher, W. P., Jr.; Massof, R. W.

    2016-11-01

    Obtaining a clear image of the world depends on good eye coordination (“binocular vision”). Yet no standard exists by which to determine a threshold for good vs poor binocular vision, as exists for the eye chart and visual acuity. We asked whether data on the signs and symptoms related to binocular vision are sufficiently consistent with children's self-reported visual symptoms to substantiate a construct model of Functional Binocular Vision (FBV), and then whether that model can be used to aggregate clinical and survey observations into a meaningful diagnostic measure. Data on visual symptoms from 1,100 children attending school in Los Angeles were obtained using the Convergence Insufficiency Symptom Survey (CISS); and for more than 300 students in that sample, 35 additional measures were taken, including acuity, cover test near and far, near point of convergence, near point of accommodation, accommodative facility, vergence ranges, tracking ability, and oral reading fluency. A preliminary analysis of data from the 15-item, 5-category CISS and 15 clinical variables from 103 grade school students who reported convergence problems (CISS scores of 16 or higher) suggests that the clinical and survey observations will be optimally combined in a multidimensional model.

  9. Effect of gene therapy on visual function in Leber's congenital amaurosis.

    PubMed

    Bainbridge, James W B; Smith, Alexander J; Barker, Susie S; Robbie, Scott; Henderson, Robert; Balaggan, Kamaljit; Viswanathan, Ananth; Holder, Graham E; Stockman, Andrew; Tyler, Nick; Petersen-Jones, Simon; Bhattacharya, Shomi S; Thrasher, Adrian J; Fitzke, Fred W; Carter, Barrie J; Rubin, Gary S; Moore, Anthony T; Ali, Robin R

    2008-05-22

    Early-onset, severe retinal dystrophy caused by mutations in the gene encoding retinal pigment epithelium-specific 65-kD protein (RPE65) is associated with poor vision at birth and complete loss of vision in early adulthood. We administered to three young adult patients subretinal injections of recombinant adeno-associated virus vector 2/2 expressing RPE65 complementary DNA (cDNA) under the control of a human RPE65 promoter. There were no serious adverse events. There was no clinically significant change in visual acuity or in peripheral visual fields on Goldmann perimetry in any of the three patients. We detected no change in retinal responses on electroretinography. One patient had significant improvement in visual function on microperimetry and on dark-adapted perimetry. This patient also showed improvement in a subjective test of visual mobility. These findings provide support for further clinical studies of this experimental approach in other patients with mutant RPE65. (ClinicalTrials.gov number, NCT00643747 [ClinicalTrials.gov].).

  10. Predicting Adaptive Functioning of Mentally Retarded Persons in Community Settings.

    ERIC Educational Resources Information Center

    Hull, John T.; Thompson, Joy C.

    1980-01-01

    The impact of a variety of individual, residential, and community variables on adaptive functioning of 369 retarded persons (18 to 73 years old) was examined using a multiple regression analysis. Individual characteristics (especially IQ) accounted for 21 percent of the variance, while environmental variables, primarily those related to…

  11. Preschooler Sleep Patterns Related to Cognitive and Adaptive Functioning

    ERIC Educational Resources Information Center

    Keefe-Cooperman, Kathleen; Brady-Amoon, Peggy

    2014-01-01

    Research Findings: Preschoolers' sleep patterns were examined related to cognitive and adaptive functioning. The sample consisted of 874 typically developing preschool children with a mean age of 40.01 months. Parent/caregiver reports of children's sleep pattern factors, Stanford-Binet 5 intelligence scale scores, and Behavior Assessment System…

  12. Hypnotizability as a Function of Repression, Adaptive Regression, and Mood

    ERIC Educational Resources Information Center

    Silver, Maurice Joseph

    1974-01-01

    Forty male undergraduates were assessed in a personality assessment session and a hypnosis session. The personality traits studied were repressive style and adaptive regression, while the transitory variable was mood prior to hypnosis. Hypnotizability was a significant interactive function of repressive style and mood, but not of adaptive…

  13. Blood Oxygen Level-Dependent Activation of the Primary Visual Cortex Predicts Size Adaptation Illusion

    PubMed Central

    Pooresmaeili, Arezoo; Arrighi, Roberto; Biagi, Laura; Morrone, Maria Concetta

    2016-01-01

    In natural scenes, objects rarely occur in isolation but appear within a spatiotemporal context. Here, we show that the perceived size of a stimulus is significantly affected by the context of the scene: brief previous presentation of larger or smaller adapting stimuli at the same region of space changes the perceived size of a test stimulus, with larger adapting stimuli causing the test to appear smaller than veridical and vice versa. In a human fMRI study, we measured the blood oxygen level-dependent activation (BOLD) responses of the primary visual cortex (V1) to the contours of large-diameter stimuli and found that activation closely matched the perceptual rather than the retinal stimulus size: the activated area of V1 increased or decreased, depending on the size of the preceding stimulus. A model based on local inhibitory V1 mechanisms simulated the inward or outward shifts of the stimulus contours and hence the perceptual effects. Our findings suggest that area V1 is actively involved in reshaping our perception to match the short-term statistics of the visual scene. PMID:24089504

  14. Social categories shape the neural representation of emotion: evidence from a visual face adaptation task.

    PubMed

    Otten, Marte; Banaji, Mahzarin R

    2012-01-01

    A number of recent behavioral studies have shown that emotional expressions are differently perceived depending on the race of a face, and that perception of race cues is influenced by emotional expressions. However, neural processes related to the perception of invariant cues that indicate the identity of a face (such as race) are often described to proceed independently of processes related to the perception of cues that can vary over time (such as emotion). Using a visual face adaptation paradigm, we tested whether these behavioral interactions between emotion and race also reflect interdependent neural representation of emotion and race. We compared visual emotion aftereffects when the adapting face and ambiguous test face differed in race or not. Emotion aftereffects were much smaller in different race (DR) trials than same race (SR) trials, indicating that the neural representation of a facial expression is significantly different depending on whether the emotional face is black or white. It thus seems that invariable cues such as race interact with variable face cues such as emotion not just at a response level, but also at the level of perception and neural representation.

  15. An indirect adaptive neural control of a visual-based quadrotor robot for pursuing a moving target.

    PubMed

    Shirzadeh, Masoud; Amirkhani, Abdollah; Jalali, Aliakbar; Mosavi, Mohammad R

    2015-11-01

    This paper aims to use a visual-based control mechanism to control a quadrotor type aerial robot which is in pursuit of a moving target. The nonlinear nature of a quadrotor, on the one hand, and the difficulty of obtaining an exact model for it, on the other hand, constitute two serious challenges in designing a controller for this UAV. A potential solution for such problems is the use of intelligent control methods such as those that rely on artificial neural networks and other similar approaches. In addition to the two mentioned problems, another problem that emerges due to the moving nature of a target is the uncertainty that exists in the target image. By employing an artificial neural network with a Radial Basis Function (RBF) an indirect adaptive neural controller has been designed for a quadrotor robot in search of a moving target. The results of the simulation for different paths show that the quadrotor has efficiently tracked the moving target.

  16. Visual Function after Primary Posterior Chamber Intraocular Lens Implantation in Pediatric Unilateral Cataract: Stereopsis and Visual Acuity

    PubMed Central

    Park, Jung Hyun; Kim, Jeong Hun; Kim, Seong Joon; Choung, Ho Kyung

    2007-01-01

    Purpose To investigate the association between binocular function and vision after cataract removal and primary posterior chamber intraocular lens (PC-IOL) implantation in children with unilateral cataract and to identify visual function differences according cataract type. Methods Clinical records of 2- to 6-year-old patients with unilateral cataract removal and primary PC-IOL implantation were reviewed retrospectively. Visual acuity and ocular alignment were measured. Sensory fusion was assessed with the Worth 4-dot test, and stereoacuity with the Titmus stereo test. Cataracts were classified according to cause, lens opacity location, age at onset, and presence of strabismus. Clinical characteristics of patients who obtained good visual function were identified. Results Forty-seven patients were included. Among 22 (46.8%) with good vision (20/40 or better), only 6 (27.3%) achieved good binocular function (the presence of fusion and 100 seconds of arc or better of stereoacuity). Visual acuity was better in eyes with good binocular function (p=0.002). No other variables were significant for achieving good binocular function. Conclusions The removal of unilateral cataract in a visually immature child can result in a combination of good visual acuity and binocular function. Good binocular function is closely related to good visual acuity. PMID:18063882

  17. Symmetry-adapted Wannier functions in the maximal localization procedure

    NASA Astrophysics Data System (ADS)

    Sakuma, R.

    2013-06-01

    A procedure to construct symmetry-adapted Wannier functions in the framework of the maximally localized Wannier function approach [Marzari and Vanderbilt, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.56.12847 56, 12847 (1997); Souza, Marzari, and Vanderbilt, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.65.035109 65, 035109 (2001)] is presented. In this scheme, the minimization of the spread functional of the Wannier functions is performed with constraints that are derived from symmetry properties of the specified set of the Wannier functions and the Bloch functions used to construct them, therefore one can obtain a solution that does not necessarily yield the global minimum of the spread functional. As a test of this approach, results of atom-centered Wannier functions for GaAs and Cu are presented.

  18. Functional connectivity when detecting rare visual targets in schizophrenia.

    PubMed

    Jimenez, Amy M; Lee, Junghee; Green, Michael F; Wynn, Jonathan K

    2017-03-30

    Individuals with schizophrenia demonstrate difficulties in attending to important stimuli (e.g., targets) and ignoring distractors (e.g., non-targets). We used a visual oddball task during fMRI to examine functional connectivity within and between the ventral and dorsal attention networks to determine the relative contribution of each network to detection of rare visual targets in schizophrenia. The sample comprised 25 schizophrenia patients and 27 healthy controls. Psychophysiological interaction analysis was used to examine whole-brain functional connectivity in response to targets. We used the right temporo parietal junction (TPJ) as the seed region for the ventral network and the right medial intraparietal sulcus (IPS) as the seed region for the dorsal network. We found that connectivity between right IPS and right anterior insula (AI; a component of the ventral network) was significantly greater in controls than patients. Expected patterns of within- and between-network connectivity for right TPJ were observed in controls, and not significantly different in patients. These findings indicate functional connectivity deficits between the dorsal and ventral attention networks in schizophrenia that may create problems in processing relevant versus irrelevant stimuli. Understanding the nature of network disruptions underlying cognitive deficits of schizophrenia may help shed light on the pathophysiology of this disorder.

  19. Novel in vivo techniques to visualize kidney anatomy and function.

    PubMed

    Peti-Peterdi, János; Kidokoro, Kengo; Riquier-Brison, Anne

    2015-07-01

    Intravital imaging using multiphoton microscopy (MPM) has become an increasingly popular and widely used experimental technique in kidney research over the past few years. MPM allows deep optical sectioning of the intact, living kidney tissue with submicron resolution, which is unparalleled among intravital imaging approaches. MPM has solved a long-standing critical technical barrier in renal research to study several complex and inaccessible cell types and anatomical structures in vivo in their native environment. Comprehensive and quantitative kidney structure and function MPM studies helped our better understanding of the cellular and molecular mechanisms of the healthy and diseased kidney. This review summarizes recent in vivo MPM studies with a focus on the glomerulus and the filtration barrier, although select, glomerulus-related renal vascular and tubular functions are also mentioned. The latest applications of serial MPM of the same glomerulus in vivo, in the intact kidney over several days, during the progression of glomerular disease are discussed. This visual approach, in combination with genetically encoded fluorescent markers of cell lineage, has helped track the fate and function (e.g., cell calcium changes) of single podocytes during the development of glomerular pathologies, and provided visual proof for the highly dynamic, rather than static, nature of the glomerular environment. Future intravital imaging applications have the promise to further push the limits of optical microscopy, and to advance our understanding of the mechanisms of kidney injury. Also, MPM will help to study new mechanisms of tissue repair and regeneration, a cutting-edge area of kidney research.

  20. Report on Adaptive Force, A Specific Neuromuscular Function

    PubMed Central

    Hoff, Marko; Heinke, Nancy; Bittmann, Frank

    2015-01-01

    In real life motions, as well as in sports, the adaptation of the neuromuscular systems to externally applied forces plays an important role. The term Adaptive Force (AF) shall characterize the ability of the nerve-muscle-system to adapt to impacting external forces during isometric and eccentric muscle action. The focus in this paper is on the concept of this neuromuscular action, which is not yet described in this way. A measuring system was constructed and evaluated for this specific neuromuscular function, but only the main information of the evaluation of the measuring system and the preliminary reference values are mentioned here, while an article with detailed description will be published separately. This paper concentrates on the three following points: 1) What is the peculiarity of this neuromuscular function, introduced as AF? 2) Is the measuring system able to capture its specific characteristics and which phases of measurement occur? 3) It seems reasonable to discuss if AF can be distinguished and classified among the known force concepts. The article describes the measuring system and how it is able to capture special features of real life motions like submaximal intensities and the subjects’ option to react adequately on external varying forces. Furthermore, within one measurement the system records three different force qualities: the isometric submaximal Adaptive Force (AFiso), the maximal isometric Adaptive Force (AFisomax) and the maximal eccentric Adaptive Force (AFeccmax). Each of these phases provide different and unique information on the nerve-muscle-system that are discussed in detail. Important, in terms of the Adaptive Force, seems to be the combination of conditional and coordinative abilities. This project was funded by the Federal Ministry of Economy and Technology (Project ZIM KF2262301FO9). PMID:26913155

  1. Motor adaptation in complex sports - the influence of visual context information on the adaptation of the three-point shot to altered task demands in expert basketball players.

    PubMed

    Stöckel, Tino; Fries, Udo

    2013-01-01

    We examined the influence of visual context information on skilled motor behaviour and motor adaptation in basketball. The rules of basketball in Europe have recently changed, such that that the distance for three-point shots increased from 6.25 m to 6.75 m. As such, we tested the extent to which basketball experts can adapt to the longer distance when a) only the unfamiliar, new three-point line was provided as floor markings (NL group), or b) the familiar, old three-point line was provided in addition to the new floor markings (OL group). In the present study 20 expert basketball players performed 40 three-point shots from 6.25 m and 40 shots from 6.75 m. We assessed the percentage of hits and analysed the landing position of the ball. Results showed better adaptation of throwing performance to the longer distance when the old three-point line was provided as a visual landmark, compared to when only the new three-point line was provided. We hypothesise that the three-point line delivered relevant information needed to successfully adapt to the greater distance in the OL group, whereas it disturbed performance and ability to adapt in the NL group. The importance of visual landmarks on motor adaptation in basketball throwing is discussed relative to the influence of other information sources (i.e. angle of elevation relative to the basket) and sport practice.

  2. Spatiotemporal characteristics of form analysis in the human visual cortex revealed by rapid event-related fMRI adaptation.

    PubMed

    Kourtzi, Zoe; Huberle, Elisabeth

    2005-11-01

    The integration of local elements to coherent forms is at the core of understanding visual perception. Accumulating evidence suggests that both early retinotopic and higher occipitotemporal areas contribute to the integration of local elements to global forms. However, the spatiotemporal characteristics of form analysis in the human visual cortex remain largely unknown. The aim of this study was to investigate form analysis at different spatial (global vs. local structure) and temporal (different stimulus presentation rates) scales across stages of visual analysis (from V1 to the lateral occipital complex-LOC) in the human brain. We used closed contours rendered by Gabor elements and manipulated either the global contour structure or the orientation of the local Gabor elements. Our rapid event-related fMRI adaptation studies suggest that contour integration and form processing in early visual areas is transient and limited within the local neighborhood of their cells' receptive field. In contrast, higher visual areas appear to process the perceived global form in a more sustained manner. Finally, we demonstrate that these spatiotemporal properties of form processing in the visual cortex are modulated by attention. Attention to the global form maintains sustained processing in occipitotemporal areas, whereas attention to local elements enhances their integration in early visual areas. These findings provide novel neuroimaging evidence for form analysis at different spatiotemporal scales across human visual areas and validate the use of rapid event-related fMRI adaptation for investigating processing across stages of visual analysis in the human brain.

  3. A MATLAB function for 3-D and 4-D topographical visualization in geosciences

    NASA Astrophysics Data System (ADS)

    Zekollari, Harry

    2016-04-01

    Combining topographical information and spatially varying variables in visualizations is often crucial and inherent to geoscientific problems. Despite this, it is often an impossible or a very time-consuming and difficult task to create such figures by using classic software packages. This is also the case in the widely used numerical computing environment MATLAB. Here a MATLAB function is introduced for plotting a variety of natural environments with a pronounced topography, such as for instance glaciers, volcanoes and lakes in mountainous regions. Landscapes can be visualized in 3-D, with a single colour defining a featured surface type (e.g. ice, snow, water, lava), or with a colour scale defining the magnitude of a variable (e.g. ice thickness, snow depth, water depth, surface velocity, gradient, elevation). As an input only the elevation of the subsurface (typically the bedrock) and the surface are needed, which can be complemented by various input parameters in order to adapt the figure to specific needs. The figures are particularly suited to make time-evolving animations of natural processes, such as for instance a glacier retreat or a lake drainage event. Several visualization examples will be provided alongside with animations. The function, which is freely available for download, only requires the basic package of MATLAB and can be run on any standard stationary or portable personal computer.

  4. Impact of Adaptive Materials on Teachers and their Students with Visual Impairments in Secondary Science and Mathematics Classes

    NASA Astrophysics Data System (ADS)

    Rule, Audrey C.; Stefanich, Greg P.; Boody, Robert M.; Peiffer, Belinda

    2011-04-01

    Science, technology, engineering, and mathematics (STEM) fields, important in today's world, are underrepresented by students with disabilities. Students with visual impairments, although cognitively similar to sighted peers, face challenges as STEM subjects are often taught using visuals. They need alternative forms of access such as enlarged or audio-converted text, tactile graphics, and involvement in hands-on science. This project focused on increasing teacher awareness of and providing funds for the purchase of supplemental adaptive resources, supplies, and equipment. We examined attitude and instructional changes across the year of the programme in 15 science and mathematics teachers educating students with visual impairments. Positive changes were noted from pretest to posttest in student and teacher perspectives, and in teacher attitudes towards students with disabilities in STEM classes. Teachers also provided insights into their challenges and successes through a reflective narrative. Several adolescent students resisted accommodations to avoid appearing conspicuous to peers. Teachers implemented three strategies to address this: providing the adaptations to all students in the class; convincing the student of the need for adaptation; and involving the class in understanding and accepting the student's impairment. A variety of teacher-created adaptations for various science and mathematics labs are reported. Another finding was many adaptations provided for the student with visual impairment benefitted the entire class. This study supports the claim that given knowledgeable, supportive teachers, and with appropriate accommodations such as tactile or auditory materials, students with visual impairments can be as successful and engaged as other students in science and mathematics.

  5. Adapting an existing visualization application for browser-based deployment: A case study from the Tropical Rainfall Measuring Mission

    NASA Astrophysics Data System (ADS)

    Kelley, Owen A.

    2013-02-01

    THOR, the Tool for High-resolution Observation Review, is a data viewer for the Tropical Rainfall Measuring Mission (TRMM) and the upcoming Global Precipitation Measurement (GPM) mission. THOR began as a desktop application, but now it can be accessed with a web browser, making THOR one of the first online tools for visualizing TRMM satellite data (http://pps.gsfc.nasa.gov/thor). In this effort, the reuse of the existing visualization code was maximized and the complexity of new code was minimized by avoiding unnecessary functionality, frameworks, or libraries. The simplicity of this approach makes it potentially attractive to researchers wishing to adapt their visualization applications for online deployment. To enable THOR to run within a web browser, three new pieces of code are written. First, the graphical user interface (GUI) of the desktop application is translated into HTML, JavaScript, and CSS. Second, a simple communication mechanism is developed over HTTP. Third, a virtual GUI is created on the server that interfaces with the image-generating routines of the existing desktop application so that these routines do not need to be modified for online use. While the basic functionality of THOR is now available online, prototyping is ongoing for enhanced 3D imaging and other aspects of both THOR Desktop and THOR Online. Because TRMM data products are complex and periodically reprocessed with improved algorithms, having a tool such as THOR is important to analysts at the Precipitation Processing System where the algorithms are tested and the products generated, stored, and distributed. Researchers also have found THOR useful for taking a first look at individual files before writing their own software to perform specialized calculations and analyses.

  6. Object Tracking Using Adaptive Covariance Descriptor and Clustering-Based Model Updating for Visual Surveillance

    PubMed Central

    Qin, Lei; Snoussi, Hichem; Abdallah, Fahed

    2014-01-01

    We propose a novel approach for tracking an arbitrary object in video sequences for visual surveillance. The first contribution of this work is an automatic feature extraction method that is able to extract compact discriminative features from a feature pool before computing the region covariance descriptor. As the feature extraction method is adaptive to a specific object of interest, we refer to the region covariance descriptor computed using the extracted features as the adaptive covariance descriptor. The second contribution is to propose a weakly supervised method for updating the object appearance model during tracking. The method performs a mean-shift clustering procedure among the tracking result samples accumulated during a period of time and selects a group of reliable samples for updating the object appearance model. As such, the object appearance model is kept up-to-date and is prevented from contamination even in case of tracking mistakes. We conducted comparing experiments on real-world video sequences, which confirmed the effectiveness of the proposed approaches. The tracking system that integrates the adaptive covariance descriptor and the clustering-based model updating method accomplished stable object tracking on challenging video sequences. PMID:24865883

  7. Object tracking using adaptive covariance descriptor and clustering-based model updating for visual surveillance.

    PubMed

    Qin, Lei; Snoussi, Hichem; Abdallah, Fahed

    2014-05-26

    We propose a novel approach for tracking an arbitrary object in video sequences for visual surveillance. The first contribution of this work is an automatic feature extraction method that is able to extract compact discriminative features from a feature pool before computing the region covariance descriptor. As the feature extraction method is adaptive to a specific object of interest, we refer to the region covariance descriptor computed using the extracted features as the adaptive covariance descriptor. The second contribution is to propose a weakly supervised method for updating the object appearance model during tracking. The method performs a mean-shift clustering procedure among the tracking result samples accumulated during a period of time and selects a group of reliable samples for updating the object appearance model. As such, the object appearance model is kept up-to-date and is prevented from contamination even in case of tracking mistakes. We conducted comparing experiments on real-world video sequences, which confirmed the effectiveness of the proposed approaches. The tracking system that integrates the adaptive covariance descriptor and the clustering-based model updating method accomplished stable object tracking on challenging video sequences.

  8. Basal ganglia damage and impaired visual function in the newborn infant

    PubMed Central

    Mercuri, E.; Atkinson, J.; Braddick, O.; Anker, S.; Cowan, F.; Rutherford, M.; Pennock, J.; Dubowitz, L.

    1997-01-01

    AIM—To examine the effects of early lesions in the visual pathway on visual function; and to identify early prognostic indicators of visual abnormalities.
METHODS—The visual function of 37 infants with perinatal brain lesions on magnetic resonance imaging was assessed using behavioural and electrophysiological variables.
RESULTS—Normal visual behaviour was observed in most infants with large bilateral occipital lesions, but all the infants with associated basal ganglia involvement had abnormal visual function. Visual abnormalities were also present in six infants with isolated basal ganglia lesions.
CONCLUSIONS—These observations suggest that basal ganglia may have an integral role in human visual development and that their presence on neonatal MRI could be an early marker of abnormal visual function.

 PMID:9377131

  9. Genomic islands predict functional adaptation in marine actinobacteria

    SciTech Connect

    Penn, Kevin; Jenkins, Caroline; Nett, Markus; Udwary, Daniel; Gontang, Erin; McGlinchey, Ryan; Foster, Brian; Lapidus, Alla; Podell, Sheila; Allen, Eric; Moore, Bradley; Jensen, Paul

    2009-04-01

    Linking functional traits to bacterial phylogeny remains a fundamental but elusive goal of microbial ecology 1. Without this information, it becomes impossible to resolve meaningful units of diversity and the mechanisms by which bacteria interact with each other and adapt to environmental change. Ecological adaptations among bacterial populations have been linked to genomic islands, strain-specific regions of DNA that house functionally adaptive traits 2. In the case of environmental bacteria, these traits are largely inferred from bioinformatic or gene expression analyses 2, thus leaving few examples in which the functions of island genes have been experimentally characterized. Here we report the complete genome sequences of Salinispora tropica and S. arenicola, the first cultured, obligate marine Actinobacteria 3. These two species inhabit benthic marine environments and dedicate 8-10percent of their genomes to the biosynthesis of secondary metabolites. Despite a close phylogenetic relationship, 25 of 37 secondary metabolic pathways are species-specific and located within 21 genomic islands, thus providing new evidence linking secondary metabolism to ecological adaptation. Species-specific differences are also observed in CRISPR sequences, suggesting that variations in phage immunity provide fitness advantages that contribute to the cosmopolitan distribution of S. arenicola 4. The two Salinispora genomes have evolved by complex processes that include the duplication and acquisition of secondary metabolite genes, the products of which provide immediate opportunities for molecular diversification and ecological adaptation. Evidence that secondary metabolic pathways are exchanged by Horizontal Gene Transfer (HGT) yet are fixed among globally distributed populations 5 supports a functional role for their products and suggests that pathway acquisition represents a previously unrecognized force driving bacterial diversification

  10. M1 ipRGCs Influence Visual Function through Retrograde Signaling in the Retina

    PubMed Central

    Prigge, Cameron L.; Yeh, Po-Ting; Liou, Nan-Fu; Lee, Chi-Chan; You, Shih-Feng; Liu, Lei-Lei; McNeill, David S.; Chew, Kylie S.; Hattar, Samer

    2016-01-01

    Melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs, with five subtypes named M1–M5) are a unique subclass of RGCs with axons that project directly to many brain nuclei involved in non-image-forming functions such as circadian photoentrainment and the pupillary light reflex. Recent evidence suggests that melanopsin-based signals also influence image-forming visual function, including light adaptation, but the mechanisms involved are unclear. Intriguingly, a small population of M1 ipRGCs have intraretinal axon collaterals that project toward the outer retina. Using genetic mouse models, we provide three lines of evidence showing that these axon collaterals make connections with upstream dopaminergic amacrine cells (DACs): (1) ipRGC signaling to DACs is blocked by tetrodotoxin both in vitro and in vivo, indicating that ipRGC-to-DAC transmission requires voltage-gated Na+ channels; (2) this transmission is partly dependent on N-type Ca2+ channels, which are possibly expressed in the axon collateral terminals of ipRGCs; and (3) fluorescence microscopy reveals that ipRGC axon collaterals make putative presynaptic contact with DACs. We further demonstrate that elimination of M1 ipRGCs attenuates light adaptation, as evidenced by an impaired electroretinogram b-wave from cones, whereas a dopamine receptor agonist can potentiate the cone-driven b-wave of retinas lacking M1 ipRGCs. Together, the results strongly suggest that ipRGCs transmit luminance signals retrogradely to the outer retina through the dopaminergic system and in turn influence retinal light adaptation. SIGNIFICANCE STATEMENT Melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) comprise a third class of retinal photoreceptors that are known to mediate physiological responses such as circadian photoentrainment. However, investigation into whether and how ipRGCs contribute to vision has just begun. Here, we provide convergent anatomical and

  11. Neurophysiological assessment of auditory, peripheral nerve, somatosensory, and visual system functions after developmental exposure to ethanol vapors.

    PubMed

    Boyes, William K; Degn, Laura L; Martin, Sheppard A; Lyke, Danielle F; Hamm, Charles W; Herr, David W

    2014-01-01

    Ethanol-blended gasoline entered the market in response to demand for domestic renewable energy sources, and may result in increased inhalation of ethanol vapors in combination with other volatile gasoline constituents. It is important to understand potential risks of inhalation of ethanol vapors by themselves, and also as a baseline for evaluating the risks of ethanol combined with a complex mixture of hydrocarbon vapors. Because sensory dysfunction has been reported after developmental exposure to ethanol, we evaluated the effects of developmental exposure to ethanol vapors on neurophysiological measures of sensory function as a component of a larger project evaluating developmental ethanol toxicity. Pregnant Long-Evans rats were exposed to target concentrations 0, 5000, 10,000, or 21,000 ppm ethanol vapors for 6.5h/day over GD9-GD20. Sensory evaluations of male offspring began between PND106 and PND128. Peripheral nerve function (compound action potentials, nerve conduction velocity (NCV)), somatosensory (cortical and cerebellar evoked potentials), auditory (brainstem auditory evoked responses), and visual evoked responses were assessed. Visual function assessment included pattern elicited visual evoked potentials (VEPs), VEP contrast sensitivity, and electroretinograms recorded from dark-adapted (scotopic), light-adapted (photopic) flashes, and UV flicker and green flicker. No consistent concentration-related changes were observed for any of the physiological measures. The results show that gestational exposure to ethanol vapor did not result in detectable changes in peripheral nerve, somatosensory, auditory, or visual function when the offspring were assessed as adults.

  12. Functional implications of orientation maps in primary visual cortex

    NASA Astrophysics Data System (ADS)

    Koch, Erin; Jin, Jianzhong; Alonso, Jose M.; Zaidi, Qasim

    2016-11-01

    Stimulus orientation in the primary visual cortex of primates and carnivores is mapped as iso-orientation domains radiating from pinwheel centres, where orientation preferences of neighbouring cells change circularly. Whether this orientation map has a function is currently debated, because many mammals, such as rodents, do not have such maps. Here we show that two fundamental properties of visual cortical responses, contrast saturation and cross-orientation suppression, are stronger within cat iso-orientation domains than at pinwheel centres. These differences develop when excitation (not normalization) from neighbouring oriented neurons is applied to different cortical orientation domains and then balanced by inhibition from un-oriented neurons. The functions of the pinwheel mosaic emerge from these local intra-cortical computations: Narrower tuning, greater cross-orientation suppression and higher contrast gain of iso-orientation cells facilitate extraction of object contours from images, whereas broader tuning, greater linearity and less suppression of pinwheel cells generate selectivity for surface patterns and textures.

  13. Functional implications of orientation maps in primary visual cortex

    PubMed Central

    Koch, Erin; Jin, Jianzhong; Alonso, Jose M.; Zaidi, Qasim

    2016-01-01

    Stimulus orientation in the primary visual cortex of primates and carnivores is mapped as iso-orientation domains radiating from pinwheel centres, where orientation preferences of neighbouring cells change circularly. Whether this orientation map has a function is currently debated, because many mammals, such as rodents, do not have such maps. Here we show that two fundamental properties of visual cortical responses, contrast saturation and cross-orientation suppression, are stronger within cat iso-orientation domains than at pinwheel centres. These differences develop when excitation (not normalization) from neighbouring oriented neurons is applied to different cortical orientation domains and then balanced by inhibition from un-oriented neurons. The functions of the pinwheel mosaic emerge from these local intra-cortical computations: Narrower tuning, greater cross-orientation suppression and higher contrast gain of iso-orientation cells facilitate extraction of object contours from images, whereas broader tuning, greater linearity and less suppression of pinwheel cells generate selectivity for surface patterns and textures. PMID:27876796

  14. Proteins of the corneal stroma: importance in visual function.

    PubMed

    Xuan, Meng; Wang, Shurong; Liu, Xin; He, Yuxi; Li, Ying; Zhang, Yan

    2016-04-01

    The human cornea, consisting of five layers, is the transparent tissue that refracts and transmits light to the lens and retina, providing about two thirds of the refractive power of the eye. The stroma layer comprises nearly 90 % of the thickness of the cornea and thus plays a pivotal role in normal visual function. The bulk of this layer is constituted by proteins in the extracellular martrix secreted by the corneal epithelial, stroma, and endothelial cells. Clinical research has shown that corneal stroma diseases are common and involve conditions such as infections, injuries, and genetic defects, which cause severe visual disturbances or even blindness. To improve our understanding of the basic molecular mechanisms involved in the physiological and pathological activities of the corneal stroma, its proteins have been brought into the limelight to determine their crucial and irreplaceable roles. The data presented in a previous study have demonstrated the presence of 1679 proteins in the stroma, and this data set has subsequently been perfected by utilizing a highly sensitive isobaric peptide-labeling approach. According to their manifestations, these proteins can be classified as a gel-like organic material composed of proteoglycans, enzymes, and hemocyanin-binding proteins and a network of filaments composed of collagen, elastin, keratin, vimentin, and interconnected filaments comprising fibronectin and laminin. The aim of this review is to describe some corneal stroma proteins by highlighting their major functions and valuable applications in ophthalmologic research toward the better characterization and treatment of eye diseases.

  15. Functional tissue pulsatility imaging of the brain during visual stimulation.

    PubMed

    Kucewicz, John C; Dunmire, Barbrina; Leotta, Daniel F; Panagiotides, Heracles; Paun, Marla; Beach, Kirk W

    2007-05-01

    Functional tissue pulsatility imaging is a new ultrasonic technique being developed to map brain function by measuring changes in tissue pulsatility as a result of changes in blood flow with neuronal activation. The technique is based in principle on plethysmography, an older, nonultrasound technology for measuring expansion of a whole limb or body part as a result of perfusion. Perfused tissue expands by a fraction of a percent early in each cardiac cycle when arterial inflow exceeds venous outflow, and it relaxes later in the cardiac cycle when venous drainage dominates. Tissue pulsatility imaging (TPI) uses tissue Doppler signal processing methods to measure this pulsatile "plethysmographic" signal from hundreds or thousands of sample volumes in an ultrasound image plane. A feasibility study was conducted to determine if TPI could be used to detect regional brain activation during a visual contrast-reversing checkerboard block paradigm study. During a study, ultrasound data were collected transcranially from the occipital lobe as a subject viewed alternating blocks of a reversing checkerboard (stimulus condition) and a static, gray screen (control condition). Multivariate analysis of variance was used to identify sample volumes with significantly different pulsatility waveforms during the control and stimulus blocks. In 7 of 14 studies, consistent regions of activation were detected from tissue around the major vessels perfusing the visual cortex.

  16. Functioning, Disability, and Social Adaptation Six Months After Burn Injury.

    PubMed

    Palmu, Raimo; Partonen, Timo; Suominen, Kirsi; Vuola, Jyrki; Isometsä, Erkki

    2016-01-01

    Major injuries commonly cause long-standing functional impairment. The authors investigated the levels of and predictors for functioning, disability, and social adaptation 6 months after a burn injury. The overall level of functioning at 6 months postburn was assessed among 87 (81%) of the 107 consecutive acute adult burn patients (mean TBSA 9.7%) admitted to the Helsinki Burn Centre during an 18-month period. Social and Occupational Functioning Assessment Scale (SOFAS) was used to evaluate functioning overall, and Sheehan Disability Scale (SDS) to assess the domains of working capacity, social life, and family life. Social Adaptation Self-Evaluation Scale (SASS) was used to measure social adaptation. Structured clinical interview was used to assess mental disorders at baseline and 6 months after injury. The mean SOFAS score was 69.7 (SD = 20.8), indicating some impairment in social and occupational functioning. The strongest independent predictors of SOFAS were mental disorders during follow-up (P < .001), particularly major depressive disorder (P < .001) and delirium (P = .016), but also length of stay (P = .004) and hand burn (P = .012). Concerning disability (SDS), the authors found mild impairment in all three domains, the most in SDS work (mean 3.59, SD = 3.46). The strongest predictor of SDS was major depressive disorder during follow-up (P < .001) and of SASS personality disorders (P = .007). Six months after a burn injury, some difficulties in social and occupational functioning remained. Level of functioning was predicted strongly and consistently by mental disorders, particularly depression. Length of stay and hand burns also predicted functioning, more in a clinician's evaluation (SOFAS) than in self-reported measures (SDS and SASS).

  17. Windows into the Visual Brain: New Discoveries about the Visual System, Its Functions, and Implications for Practitioners

    ERIC Educational Resources Information Center

    Jan, James E.; Heaven, Roberta K. B.; Matsuba, Carey; Langley, M. Beth; Roman-Lantzy, Christine; Anthony, Tanni L

    2013-01-01

    Introduction: In recent years, major progress has been made in understanding the human visual system because of new investigative techniques. These developments often contradict older concepts about visual function. Methods: A detailed literature search and interprofessional discussions. Results: Recent innovative neurological tests are described…

  18. The adaptive response of jaw muscles to varying functional demands.

    PubMed

    Grünheid, Thorsten; Langenbach, Geerling E J; Korfage, Joannes A M; Zentner, Andrej; van Eijden, Theo M G J

    2009-12-01

    Jaw muscles are versatile entities that are able to adapt their anatomical characteristics, such as size, cross-sectional area, and fibre properties, to altered functional demands. The dynamic nature of muscle fibres allows them to change their phenotype to optimize the required contractile function while minimizing energy use. Changes in these anatomical parameters are associated with changes in neuromuscular activity as the pattern of muscle activation by the central nervous system plays an important role in the modulation of muscle properties. This review summarizes the adaptive response of jaw muscles to various stimuli or perturbations in the orofacial system and addresses general changes in muscles as they adapt, specific adaptive changes in jaw muscles under various physiologic and pathologic conditions, and their adaptive response to non-surgical and surgical therapeutic interventions. Although the jaw muscles are used concertedly in the masticatory system, their adaptive changes are not always uniform and vary with the nature, intensity, and duration of the stimulus. In general, stretch, increases neuromuscular activity, and resistance training result in hypertrophy, elicits increases in mitochondrial content and cross-sectional area of the fibres, and may change the fibre-type composition of the muscle towards a larger percentage of slow-type fibres. In contrast, changes in the opposite direction occur when neuromuscular activity is reduced, the muscle is immobilized in a shortened position, or paralysed. The broad range of stimuli that affect the properties of jaw muscles might help explain the large variability in the anatomical and physiological characteristics found among individuals, muscles, and muscle portions.

  19. Effect of Acetazolamide on Visual Function in Patients With Idiopathic Intracranial Hypertension and Mild Visual Loss

    PubMed Central

    2015-01-01

    IMPORTANCE Acetazolamide is commonly used to treat idiopathic intracranial hypertension (IIH), but there is insufficient information to establish an evidence base for its use. OBJECTIVE To determine whether acetazolamide is beneficial in improving vision when added to a low-sodium weight reduction diet in patients with IIH and mild visual loss. DESIGN, SETTING, AND PARTICIPANTS Multicenter, randomized, double-masked, placebo-controlled study of acetazolamide in 165 participants with IIH and mild visual loss who received a low-sodium weight-reduction diet. Participants were enrolled at 38 academic and private practice sites in North America from March 2010 to November 2012 and followed up for 6 months (last visit in June 2013). All participants met the modified Dandy criteria for IIH and had a perimetric mean deviation (PMD) between −2 dB and −7 dB. The mean age was 29 years and all but 4 participants were women. INTERVENTIONS Low-sodium weight-reduction diet plus the maximally tolerated dosage or acetazolamide (up to 4 g/d) or matching placebo for 6 months. MAIN OUTCOMES AND MEASURES The planned primary outcome variable was the change in PMD from baseline to month 6 in the most affected eye, as measured by Humphrey Field Analyzer. Perimetric mean deviation is a measure of global visual field loss (mean deviation from age-corrected normal values), with a range of 2 to −32 dB; larger negative values indicate greater vision loss. Secondary outcome variables included changes in papilledema grade, quality of life (Visual Function Questionnaire 25 [VFQ-25] and 36-Item Short Form Health Survey), headache disability, and weight at month 6. RESULTS The mean improvement in PMD was greater with acetazolamide (1.43 dB, from −3.53 dB at baseline to −2.10 dB at month 6; n = 86) than with placebo (0.71 dB, from −3.53 dB to −2.82 dB;n = 79); the difference was 0.71 dB (95% CI, 0 to 1.43 dB; P= .050). Mean improvements in papilledema grade (acetazolamide: −1

  20. Contribution of a visual pigment absorption spectrum to a visual function: depth perception in a jumping spider.

    PubMed

    Nagata, Takashi; Arikawa, Kentaro; Terakita, Akihisa

    2013-01-01

    Absorption spectra of visual pigments are adaptively tuned to optimize informational capacity in most visual systems. Our recent investigation of the eyes of the jumping spider reveals an apparent exception: the absorption characteristics of a visual pigment cause defocusing of the image, reducing visual acuity generally in a part of the retina. However, the amount of defocus can theoretically provide a quantitative indication of the distance of an object. Therefore, we proposed a novel mechanism for depth perception in jumping spiders based on image defocus. Behavioral experiments revealed that the depth perception of the spider depended on the wavelength of the ambient light, which affects the amount of defocus because of chromatic aberration of the lens. This wavelength effect on depth perception was in close agreement with theoretical predictions based on our hypothesis. These data strongly support the hypothesis that the depth perception mechanism of jumping spiders is based on image defocus.

  1. Duration of pulmonary function adaptation to ozone in humans

    SciTech Connect

    Kulle, T.J.; Sauder, L.R.; Kerr, H.D.; Farrell, B.P.; Bermel, M.S.; Smith, D.M.

    1982-11-01

    The duration of pulmonary function adaptation subsequent to cessation of a 5-day repeated ozone (O/sub 3/) exposure was studied in 24 nonsmoking human subjects. A three-week, 3 hr/day study ws conducted. The subjects received filtered air on Week 1 and 0.4 ppm O/sub 3/ on Week 2. During Week 3, 13 subjects were re-exposed to O/sub 3/ on Friday and 11 were re-exposed to O/sub 3/ on Tuesday. Spirometric measurements (FVC and FEV/sub 1/) and bronchial reactivity to methacholine showed adapation within 2-3 days of the repeated daily exposures (Week 2). Although the duration of adaptation seen with bronchial reactivity appears longer than 7-days, the FVC and FEV/sub 1/ clearly demonstrated complete loss of adaptation by 7 days, with a trend toward significance by 4 days. We concluded, therefore, the loss of ozone adaptation in pulmonary function is a gradual phenomenon lasting less than 7 days following cessation of repeated daily exposures.

  2. Effects of the AMPA Antagonist ZK 200775 on Visual Function: A Randomized Controlled Trial

    PubMed Central

    Bergholz, Richard; Staks, Thomas; Rüther, Klaus

    2010-01-01

    Background ZK 200775 is an antagonist at the α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor and had earned attention as a possible neuroprotective agent in cerebral ischemia. Probands receiving the agent within phase I trials reported on an alteration of visual perception. In this trial, the effects of ZK 200775 on the visual system were analyzed in detail. Methodology In a randomised controlled trial we examined eyes and vision before and after the intravenous administration of two different doses of ZK 200775 and placebo. There were 3 groups of 6 probands each: Group 1 recieved 0.03 mg/kg/h, group 2 0.75 mg/kg/h of ZK 200775, the control group received 0.9% sodium chloride solution. Probands were healthy males aged between 57 and 69 years. The following methods were applied: clinical examination, visual acuity, ophthalmoscopy, colour vision, rod absolute threshold, central visual field, pattern-reversal visual evoked potentials (pVEP), ON-OFF and full-field electroretinogram (ERG). Principal Findings No effect of ZK 200775 was seen on eye position or motility, stereopsis, pupillary function or central visual field testing. Visual acuity and dark vision deteriorated significantly in both treated groups. Color vision was most remarkably impaired. The dark-adapted ERG revealed a reduction of oscillatory potentials (OP) and partly of the a- and b-wave, furthermore an alteration of b-wave morphology and an insignificantly elevated b/a-ratio. Cone-ERG modalities showed decreased amplitudes and delayed implicit times. In the ON-OFF ERG the ON-answer amplitudes increased whereas the peak times of the OFF-answer were reduced. The pattern VEP exhibited lower amplitudes and prolonged peak times. Conclusions The AMPA receptor blockade led to a strong impairment of typical OFF-pathway functions like color vision and the cone ERG. On the other hand the ON-pathway as measured by dark vision and the scotopic ERG was affected as well. This further elucidates

  3. The Reliability of the CVI Range: A Functional Vision Assessment for Children with Cortical Visual Impairment

    ERIC Educational Resources Information Center

    Newcomb, Sandra

    2010-01-01

    Children who are identified as visually impaired frequently have a functional vision assessment as one way to determine how their visual impairment affects their educational performance. The CVI Range is a functional vision assessment for children with cortical visual impairment. The purpose of the study presented here was to examine the…

  4. Novel in vivo techniques to visualize kidney anatomy and function

    PubMed Central

    Peti-Peterdi, János; Kidokoro, Kengo; Riquier-Brison, Anne

    2015-01-01

    Intravital imaging using multiphoton microscopy (MPM) has become an increasingly popular and widely used experimental technique in kidney research over the past few years. MPM allows deep optical sectioning of the intact, living kidney tissue with submicron resolution which is unparalleled among intravital imaging approaches. MPM has solved a long-standing critical technical barrier in renal research to study several complex and inaccessible cell types and anatomical structures in vivo in their native environment. Comprehensive and quantitative kidney structure and function MPM studies helped our better understanding of the cellular and molecular mechanisms of the healthy and diseased kidney. This review summarizes recent in vivo MPM studies with a focus on the glomerulus and the filtration barrier, although select, glomerulus-related renal vascular and tubular functions are also mentioned. The latest applications of serial MPM of the same glomerulus in vivo, in the intact kidney over several days, during the progression of glomerular disease are discussed. This visual approach, in combination with genetically encoded fluorescent markers of cell lineage, has helped to track the fate and function (e.g. cell calcium changes) of single podocytes during the development of glomerular pathologies, and provided visual proof for the highly dynamic rather than static nature of the glomerular environment. Future intravital imaging applications have the promise to further push the limits of optical microscopy, and to advance our understanding of the mechanisms of kidney injury. Also, MPM will help to study new mechanisms of tissue repair and regeneration, a cutting edge area of kidney research. PMID:25738253

  5. Visual input controls the functional activity of goldfish Mauthner neuron through the reciprocal synaptic mechanism.

    PubMed

    Moshkov, Dmitry A; Shtanchaev, Rashid S; Mikheeva, Irina B; Bezgina, Elena N; Kokanova, Nadezhda A; Mikhailova, Gulnara Z; Tiras, Nadezhda R; Pavlik, Lyubov' L

    2013-03-01

    Goldfish are known to exhibit motor asymmetry due to functional asymmetry of their Mauthner neurons that induce the turns to the right or left during free swimming. It has been previously found that if the less active neuron is subjected to prolonged aimed visual stimulation via its ventral dendrite, the motor asymmetry of goldfish is inverted, testifying that this neuron becomes functionally dominant, while the size of the ventral dendrite under these conditions is reduced 2-3 times compared to its counterpart in mirror neuron. Earlier it has been also revealed that training optokinetic stimulation induces adaptation, a substantial resistance of both fish motor asymmetry and morphofunctional state of Mauthner neurons against prolonged optokinetic stimulation. The aim of this work was to study the cellular mechanisms of the effect of an unusual visual afferent input on goldfish motor asymmetry and Mauthner neuron function in norm and under adaptation. It was shown that serotonin applied onto Mauthner neurons greatly reduces their activity whereas its antagonist ondansetron increases it. Against the background of visual stimulation, serotonin strengthens functional asymmetry between neurons whereas ondansetron smoothes it. Taken together these data suggest the involvement of serotonergic excitatory synaptic transmission in the regulation of Mauthner neurons by vision. Ultrastructural study of the ventral dendrites after prolonged optokinetic stimulation has revealed depletions of numeral axo-axonal synapses with specific morphology, identified by means of immunogold label as serotonergic ones. These latter in turn are situated mainly on shaft boutons, which according to specific ultrastructural features are assigned to axo-dendritic inhibitory synapses. Thus, the excitatory serotonergic synapses seem to affect Mauthner neuron indirectly through inhibitory synapses. Further, it was morphometrically established that adaptation is accompanied by the significant

  6. Visually induced self-motion sensation adapts rapidly to left-right reversal of vision

    NASA Technical Reports Server (NTRS)

    Oman, C. M.; Bock, O. L.

    1981-01-01

    Three experiments were conducted using 15 adult volunteers with no overt oculomotor or vestibular disorders. In all experiments, left-right vision reversal was achieved using prism goggles, which permitted a binocular field of vision subtending approximately 45 deg horizontally and 28 deg vertically. In all experiments, circularvection (CV) was tested before and immediately after a period of exposure to reversed vision. After one to three hours of active movement while wearing vision-reversing goggles, 10 of 15 (stationary) human subjects viewing a moving stripe display experienced a self-rotation illusion in the same direction as seen stripe motion, rather than in the opposite (normal) direction, demonstrating that the central neural pathways that process visual self-rotation cues can undergo rapid adaptive modification.

  7. Paradoxical visuomotor adaptation to reversed visual input is predicted by BDNF Val66Met polymorphism

    PubMed Central

    Barton, Brian; Treister, Andrew; Humphrey, Melanie; Abedi, Garen; Cramer, Steven C.; Brewer, Alyssa A.

    2014-01-01

    Brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the brain, influencing neural development, plasticity, and repair (Chen et al., 2004; Thoenen, 1995). The BDNF gene contains a single-nucleotide polymorphism (SNP) called Val66Met. The Met allele interferes with intracellular BDNF-trafficking, decreases activity-dependent BDNF secretion, and consequently is often associated with a shift from plasticity to stability in neural circuits (Egan et al., 2003). We investigated the behavioral consequences of the presence of the Met allele by comparing how 40 heterozygous subjects with the Val/Met genotype and 35 homozygous subjects with the Val/Val genotype performed on visuomotor tasks (reaching and navigation) under two conditions: normal vision and completely left-right reversed vision. As expected, subjects did not differ in their short-term ability to learn the tasks with normal vision (p = 0.58). Intuitively, it would be expected that homozygous Val/Val subjects with a propensity for greater BDNF-induced activity-dependent plasticity would learn new tasks more quickly than heterozygous Val/Met subjects with decreased BDNF secretion (Gilbert, Li, & Piech, 2009). However, we found the opposite here. When short-term mechanisms of visuomotor adaptation were engaged to compensate for the misalignment of visual and somatomotor information created by the left-right reversal of vision, heterozygous Val/Met subjects learned significantly more quickly than their homozygous Val/Val counterparts (p = 0.027). Our results demonstrate the paradoxical finding that the presence of the Met allele, which is thought to promote cortical stability, here improves immediate visuomotor adaptation to left–right-reversed visual input. PMID:25104829

  8. Adaptive Shape Functions and Internal Mesh Adaptation for Modelling Progressive Failure in Adhesively Bonded Joints

    NASA Technical Reports Server (NTRS)

    Stapleton, Scott; Gries, Thomas; Waas, Anthony M.; Pineda, Evan J.

    2014-01-01

    Enhanced finite elements are elements with an embedded analytical solution that can capture detailed local fields, enabling more efficient, mesh independent finite element analysis. The shape functions are determined based on the analytical model rather than prescribed. This method was applied to adhesively bonded joints to model joint behavior with one element through the thickness. This study demonstrates two methods of maintaining the fidelity of such elements during adhesive non-linearity and cracking without increasing the mesh needed for an accurate solution. The first method uses adaptive shape functions, where the shape functions are recalculated at each load step based on the softening of the adhesive. The second method is internal mesh adaption, where cracking of the adhesive within an element is captured by further discretizing the element internally to represent the partially cracked geometry. By keeping mesh adaptations within an element, a finer mesh can be used during the analysis without affecting the global finite element model mesh. Examples are shown which highlight when each method is most effective in reducing the number of elements needed to capture adhesive nonlinearity and cracking. These methods are validated against analogous finite element models utilizing cohesive zone elements.

  9. Is visual-based, online control of manual-aiming movements disturbed when adapting to new movement dynamics?

    PubMed

    Mackrous, Isabelle; Proteau, Luc

    2015-05-01

    Previous research has shown that for goal-directed movements, online visual feedback is not necessary for the adaptation of movement planning to novel movement dynamics. In the present study, we wanted to put this proposition to a stringent test and determine whether the usually dominant role of online visual feedback in movement control is diminished when goal-directed movements are performed in a condition that modifies limb dynamics. Participants performed a video-aiming task while the center of mass of their forearm was experimentally displaced by a 1.5-kg mass attached laterally to its longitudinal axis. A cursor representing the position of the participant's hand was either visible or not visible during the acquisition phase. Then, in a transfer test, the participants performed the task without online visual feedback and either with or without the lateral mass. During the acquisition phase, the participants adapted to the new movement dynamics imposed by the added mass regardless of whether online visual feedback was available. An important new finding of the present study was the observation that the role usually played by online visual feedback in refining movement planning and ensuring control of the initial portion of goal-directed movements was suppressed during adaptation to novel movement dynamics. This resulted in an increase in the role played by visual feedback late in the movement to ensure endpoint accuracy.

  10. Generalized pattern search algorithms with adaptive precision function evaluations

    SciTech Connect

    Polak, Elijah; Wetter, Michael

    2003-05-14

    In the literature on generalized pattern search algorithms, convergence to a stationary point of a once continuously differentiable cost function is established under the assumption that the cost function can be evaluated exactly. However, there is a large class of engineering problems where the numerical evaluation of the cost function involves the solution of systems of differential algebraic equations. Since the termination criteria of the numerical solvers often depend on the design parameters, computer code for solving these systems usually defines a numerical approximation to the cost function that is discontinuous with respect to the design parameters. Standard generalized pattern search algorithms have been applied heuristically to such problems, but no convergence properties have been stated. In this paper we extend a class of generalized pattern search algorithms to a form that uses adaptive precision approximations to the cost function. These numerical approximations need not define a continuous function. Our algorithms can be used for solving linearly constrained problems with cost functions that are at least locally Lipschitz continuous. Assuming that the cost function is smooth, we prove that our algorithms converge to a stationary point. Under the weaker assumption that the cost function is only locally Lipschitz continuous, we show that our algorithms converge to points at which the Clarke generalized directional derivatives are nonnegative in predefined directions. An important feature of our adaptive precision scheme is the use of coarse approximations in the early iterations, with the approximation precision controlled by a test. Such an approach leads to substantial time savings in minimizing computationally expensive functions.

  11. Reduced plantar sole sensitivity facilitates early adaptation to a visual rotation pointing task when standing upright

    PubMed Central

    Maxime, Billot; Léandre, Gagné Lemieux; Mathieu, Germain Robitaille; Martin, Simoneau

    2016-01-01

    Abstract Humans are capable of pointing to a target with accuracy. However, when vision is distorted through a visual rotation or mirror-reversed vision, the performance is initially degraded and thereafter improves with practice. There are suggestions this gradual improvement results from a sensorimotor recalibration involving initial gating of the somatosensory information from the pointing hand. In the present experiment, we examined if this process interfered with balance control by asking participants to point to targets with a visual rotation from a standing posture. This duality in processing sensory information (i.e., gating sensory signals from the hand while processing those arising from the control of balance) could generate initial interference leading to a degraded pointing performance. We hypothesized that if this is the case, the attenuation of plantar sole somatosensory information through cooling could reduce the sensorimotor interference, and facilitate the early adaptation (i.e. improvement in the pointing task). Results supported this hypothesis. These observations suggest that processing sensory information for balance control interferes with the sensorimotor recalibration process imposed by a pointing task when vision is rotated. PMID:28149394

  12. Ontogenetic adaptations in the visual systems of deep-sea crustaceans.

    PubMed

    Frank, Tamara M

    2017-04-05

    For all visually competent organisms, the driving force behind the adaptation of photoreceptors involves obtaining the best balance of resolution to sensitivity in the prevailing light regime, as an increase in sensitivity often results in a decrease in resolution. A number of marine species have an additional problem to deal with, in that the juvenile stages live in relatively brightly lit shallow (100-200 m depth) waters, whereas the adult stages have daytime depths of more than 600 m, where little downwelling light remains. Here, I present the results of electrophysiological analyses of the temporal resolution and irradiance sensitivity of juvenile and adult stages of two species of ontogenetically migrating crustaceans (Gnathophausia ingens and Systellaspis debilis) that must deal with dramatically different light environments and temperatures during their life histories. The results demonstrate that there are significant effects of temperature on temporal resolution, which help to optimize the visual systems of the two life-history stages for their respective light environments.This article is part of the themed issue 'Vision in dim light'.

  13. Salvaging ruins: reverting blind retinas into functional visual sensors.

    PubMed

    Mutter, Marion; Swietek, Natalia; Münch, Thomas A

    2014-01-01

    Blindness is one of the most devastating conditions affecting the quality of life. Hereditary degenerative diseases, such as retinitis pigmentosa, are characterized by the progressive loss of photoreceptors, leading to complete blindness. No treatment is known, the current state-of-the-art of restoring vision are implanted electrode arrays. As a recently discovered alternative, optical neuromodulators, such as channelrhodopsin, allow new strategies for treating these diseases by imparting light-sensitivity onto the remaining retinal neurons after photoreceptor cell death. Retinal degeneration is a heterogeneous set of diseases with diverse secondary effects on the retinal circuitry. Successful treatment strategies have to take into account this diversity, as only the existing retinal hardware can serve as substrate for optogenetic intervention. The goal is to salvage the retinal ruins and to revert the leftover tissue into a functional visual sensor that operates as optimally as possible. Here, we discuss three different successful approaches that have been applied to degenerated mouse retina.

  14. Optopharmacological tools for restoring visual function in degenerative retinal diseases

    PubMed Central

    Tochitsky, Ivan; Kramer, Richard H

    2015-01-01

    Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are progressive retinal diseases that result from the death of rod and cone photoreceptors, ultimately leading to blindness. The only currently approved vision restoration treatment employs an implanted retinal ‘chip’ as a prosthetic device to electrically stimulate retinal neurons that survive after the photoreceptors are gone, thereby restoring light-driven neural signaling to the brain. An alternative strategy has been proposed, which would utilize optogenetic or opto-pharmacological tools to enable direct optical stimulation of surviving retinal neurons. Here, we review the latest studies evaluating the feasibility of these molecular tools as potential therapeutics for restoring visual function in human blinding disease. PMID:25706312

  15. A complex-valued nonlinear neural adaptive filter with a gradient adaptive amplitude of the activation function.

    PubMed

    Hanna, Andrew I; Mandic, Danilo P

    2003-03-01

    A complex-valued nonlinear gradient descent (CNGD) learning algorithm for a simple finite impulse response (FIR) nonlinear neural adaptive filter with an adaptive amplitude of the complex activation function is proposed. This way the amplitude of the complex-valued analytic nonlinear activation function of a neuron in the learning algorithm is made gradient adaptive to give the complex-valued adaptive amplitude nonlinear gradient descent (CAANGD). Such an algorithm is beneficial when dealing with signals that have rich dynamical behavior. Simulations on the prediction of complex-valued coloured and nonlinear input signals show the gradient adaptive amplitude, CAANGD, outperforming the standard CNGD algorithm.

  16. Seeing with Profoundly Deactivated Mid-level Visual Areas: Non-hierarchical Functioning in the Human Visual Cortex

    PubMed Central

    Gilaie-Dotan, Sharon; Perry, Anat; Bonneh, Yoram; Malach, Rafael

    2009-01-01

    A fundamental concept in visual processing is that activity in high-order object-category distinctive regions (e.g., lateral occipital complex, fusiform face area, middle temporal+) is dependent on bottom-up flow of activity in earlier retinotopic areas (V2, V3, V4) whose main input originates from primary visual cortex (V1). Thus, activity in down stream areas should reflect lower-level inputs. Here we qualify this notion reporting case LG, a rare case of developmental object agnosia and prosopagnosia. In this person, V1 was robustly activated by visual stimuli, yet intermediate areas (V2–V4) were strongly deactivated. Despite this intermediate deactivation, activity in down stream visual areas remained robust, showing selectivity for houses and places, while selectivity for faces and objects was impaired. The extent of impairment evident in functional magnetic resonance imaging and electroencephalography activations was somewhat larger in the left hemisphere. This pattern of brain activity, coupled with fairly adequate everyday visual performance is compatible with models emphasizing the role of nonlinear local “amplification” of neuronal inputs in eliciting activity in ventral and dorsal visual pathways as well as perceptual experience in the human brain. Thus, while the proper functioning of intermediate areas appears essential for specialization in the cortex, daily visual behavior and reading are maintained even with deactivated intermediate visual areas. PMID:19015369

  17. Visualization of Time-Series Sensor Data to Inform the Design of Just-In-Time Adaptive Stress Interventions.

    PubMed

    Sharmin, Moushumi; Raij, Andrew; Epstien, David; Nahum-Shani, Inbal; Beck, J Gayle; Vhaduri, Sudip; Preston, Kenzie; Kumar, Santosh

    2015-09-01

    We investigate needs, challenges, and opportunities in visualizing time-series sensor data on stress to inform the design of just-in-time adaptive interventions (JITAIs). We identify seven key challenges: massive volume and variety of data, complexity in identifying stressors, scalability of space, multifaceted relationship between stress and time, a need for representation at multiple granularities, interperson variability, and limited understanding of JITAI design requirements due to its novelty. We propose four new visualizations based on one million minutes of sensor data (n=70). We evaluate our visualizations with stress researchers (n=6) to gain first insights into its usability and usefulness in JITAI design. Our results indicate that spatio-temporal visualizations help identify and explain between- and within-person variability in stress patterns and contextual visualizations enable decisions regarding the timing, content, and modality of intervention. Interestingly, a granular representation is considered informative but noise-prone; an abstract representation is the preferred starting point for designing JITAIs.

  18. Translation, cultural adaptation and reproducibility of the Cochin Hand Functional Scale questionnaire for Brazil

    PubMed Central

    Chiari, Aline; de Souza Sardim, Carla Caires; Natour, Jamil

    2011-01-01

    OBJECTIVE: To translate, to perform a cultural adaptation of and to test the reproducibility of the Cochin Hand Functional Scale questionnaire for Brazil. METHODS: First, the Cochin Hand Functional Scale questionnaire was translated into Portuguese and was then back-translated into French. These translations were reviewed by a committee to establish a Brazilian version of the questionnaire to be tested. The validity and reproducibility of the Cochin Hand Functional Scale questionnaire was evaluated. Patients of both sexes, who were aged 18 to 60 years and presented with rheumatoid arthritis affecting their hands, were interviewed. The patients were initially interviewed by two observers and were later interviewed by a single rater. First, the Visual Analogue Scale for hand pain, the Arm, Shoulder and Hand Disability questionnaire and the Health Assessment Questionnaire were administered. The third administration of the Cochin Hand Functional Scale was performed fifteen days after the first administration. Ninety patients were assessed in the present study. RESULTS: Two questions were modified as a result of the assessment of cultural equivalence. The Cronbach's alpha value for this assessment was 0.93. The intraclass intraobserver and interobserver correlation coefficients were 0.76 and 0.96, respectively. The Spearman's coefficient indicated that there was a low level of correlation between the Cochin Hand Functional Scale and the Visual Analogue Scale for pain (0.46) and that there was a moderate level of correlation of the Cochin Scale with the Health Assessment Questionnaire (0.66) and with the Disability of the Arm, Shoulder and Hand questionnaire (0.63). The average administration time for the Cochin Scale was three minutes. CONCLUSION: The Brazilian version of the Cochin Hand Functional Scale was successfully translated and adapted, and this version exhibited good internal consistency, reliability and construct validity. PMID:21789372

  19. Intersensory Function in Newborns: Effect of Sound on Visual Preferences.

    ERIC Educational Resources Information Center

    Lawson, Katharine Rieke; Turkewitz, Gerald

    1980-01-01

    Newborn infants' fixation of a graduated series of visual stimuli significantly differed in the absence and presence of white-noise bursts. Relative to the no-sound condition, sound resulted in the infants' tendency to look more at the low-intensity visual stimulus and less at the high- intensity visual stimulus. (Author/DB)

  20. The adaptation dynamics of chronic functional impairment: what we can learn from older adults with vision loss.

    PubMed

    Schilling, Oliver K; Wahl, Hans-Werner; Horowitz, Amy; Reinhardt, Joann P; Boerner, Kathrin

    2011-03-01

    This study used vision loss due to age-related macular degeneration to learn about adaptation processes related to chronic functional impairment, focusing on Horowitz and Reinhardt's (1998) concept of Adaptation to Age-related Vision Loss (AVL) as the outcome. We hypothesized that impacts of visual acuity on AVL are mediated by perceived functional vision losses and functional abilities, and tested for "adaptive" weakening of this impact with ongoing loss. Longitudinal data covering a one-year interval from samples with age-related macular degeneration gathered in New York (N = 361) and Heidelberg (Germany, N = 90) were used. We analyzed the hypothesized causal structure by modeling latent change scores, and checked if those with low, medium, and high levels of vision loss at baseline differ in the relations between one-year change scores. Results confirmed that impacts of vision loss on AVL are mediated by decline in functional ability. However, under the most severe levels of vision loss at baseline, functional decline showed only a minor impact on AVL change not explained by a lack of further decline in vision. Findings confirm the effectiveness of adaptation in terms of reduced reactivity to functional losses across increasing level of chronic impairment. Thus, adaptation, weakening the impact of chronic functional impairment on psychological outcomes over time with disease progression, deserves consideration in the study of psychological consequences of chronic physical health conditions in old age.

  1. Translation and adaptation of functional auditory performance indicators (FAPI)

    PubMed Central

    FERREIRA, Karina; MORET, Adriane Lima Mortari; BEVILACQUA, Maria Cecilia; JACOB, Regina de Souza Tangerino

    2011-01-01

    Work with deaf children has gained new attention since the expectation and goal of therapy has expanded to language development and subsequent language learning. Many clinical tests were developed for evaluation of speech sound perception in young children in response to the need for accurate assessment of hearing skills that developed from the use of individual hearing aids or cochlear implants. These tests also allow the evaluation of the rehabilitation program. However, few of these tests are available in Portuguese. Evaluation with the Functional Auditory Performance Indicators (FAPI) generates a child's functional auditory skills profile, which lists auditory skills in an integrated and hierarchical order. It has seven hierarchical categories, including sound awareness, meaningful sound, auditory feedback, sound source localizing, auditory discrimination, short-term auditory memory, and linguistic auditory processing. FAPI evaluation allows the therapist to map the child's hearing profile performance, determine the target for increasing the hearing abilities, and develop an effective therapeutic plan. Objective Since the FAPI is an American test, the inventory was adapted for application in the Brazilian population. Material and Methods The translation was done following the steps of translation and back translation, and reproducibility was evaluated. Four translated versions (two originals and two back-translated) were compared, and revisions were done to ensure language adaptation and grammatical and idiomatic equivalence. Results The inventory was duly translated and adapted. Conclusion Further studies about the application of the translated FAPI are necessary to make the test practicable in Brazilian clinical use. PMID:22230992

  2. Functional magnetic resonance imaging adaptation reveals the cortical networks for processing grasp-relevant object properties.

    PubMed

    Monaco, Simona; Chen, Ying; Medendorp, W P; Crawford, J D; Fiehler, Katja; Henriques, Denise Y P

    2014-06-01

    Grasping behaviors require the selection of grasp-relevant object dimensions, independent of overall object size. Previous neuroimaging studies found that the intraparietal cortex processes object size, but it is unknown whether the graspable dimension (i.e., grasp axis between selected points on the object) or the overall size of objects triggers activation in that region. We used functional magnetic resonance imaging adaptation to investigate human brain areas involved in processing the grasp-relevant dimension of real 3-dimensional objects in grasping and viewing tasks. Trials consisted of 2 sequential stimuli in which the object's grasp-relevant dimension, its global size, or both were novel or repeated. We found that calcarine and extrastriate visual areas adapted to object size regardless of the grasp-relevant dimension during viewing tasks. In contrast, the superior parietal occipital cortex (SPOC) and lateral occipital complex of the left hemisphere adapted to the grasp-relevant dimension regardless of object size and task. Finally, the dorsal premotor cortex adapted to the grasp-relevant dimension in grasping, but not in viewing, tasks, suggesting that motor processing was complete at this stage. Taken together, our results provide a complete cortical circuit for progressive transformation of general object properties into grasp-related responses.

  3. Testing Adaptive Hypotheses of Convergence with Functional Landscapes: A Case Study of Bone-Cracking Hypercarnivores

    PubMed Central

    Tseng, Zhijie Jack

    2013-01-01

    Morphological convergence is a well documented phenomenon in mammals, and adaptive explanations are commonly employed to infer similar functions for convergent characteristics. I present a study that adopts aspects of theoretical morphology and engineering optimization to test hypotheses about adaptive convergent evolution. Bone-cracking ecomorphologies in Carnivora were used as a case study. Previous research has shown that skull deepening and widening are major evolutionary patterns in convergent bone-cracking canids and hyaenids. A simple two-dimensional design space, with skull width-to-length and depth-to-length ratios as variables, was used to examine optimized shapes for two functional properties: mechanical advantage (MA) and strain energy (SE). Functionality of theoretical skull shapes was studied using finite element analysis (FEA) and visualized as functional landscapes. The distribution of actual skull shapes in the landscape showed a convergent trend of plesiomorphically low-MA and moderate-SE skulls evolving towards higher-MA and moderate-SE skulls; this is corroborated by FEA of 13 actual specimens. Nevertheless, regions exist in the landscape where high-MA and lower-SE shapes are not represented by existing species; their vacancy is observed even at higher taxonomic levels. Results highlight the interaction of biomechanical and non-biomechanical factors in constraining general skull dimensions to localized functional optima through evolution. PMID:23734244

  4. An Adaptive Complex Network Model for Brain Functional Networks

    PubMed Central

    Gomez Portillo, Ignacio J.; Gleiser, Pablo M.

    2009-01-01

    Brain functional networks are graph representations of activity in the brain, where the vertices represent anatomical regions and the edges their functional connectivity. These networks present a robust small world topological structure, characterized by highly integrated modules connected sparsely by long range links. Recent studies showed that other topological properties such as the degree distribution and the presence (or absence) of a hierarchical structure are not robust, and show different intriguing behaviors. In order to understand the basic ingredients necessary for the emergence of these complex network structures we present an adaptive complex network model for human brain functional networks. The microscopic units of the model are dynamical nodes that represent active regions of the brain, whose interaction gives rise to complex network structures. The links between the nodes are chosen following an adaptive algorithm that establishes connections between dynamical elements with similar internal states. We show that the model is able to describe topological characteristics of human brain networks obtained from functional magnetic resonance imaging studies. In particular, when the dynamical rules of the model allow for integrated processing over the entire network scale-free non-hierarchical networks with well defined communities emerge. On the other hand, when the dynamical rules restrict the information to a local neighborhood, communities cluster together into larger ones, giving rise to a hierarchical structure, with a truncated power law degree distribution. PMID:19738902

  5. Cocaine withdrawal and neuro-adaptations in ion channel function.

    PubMed

    Hu, Xiu-Ti

    2007-02-01

    Chronic exposure to psychostimulants induces neuro-adaptations in ion channel function of dopamine (DA)-innervated cells localized within the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc). Although neuroplasticity in ion channel function is initially found in drug-sensitized animals, it has recently been believed to underlie the withdrawal effects of cocaine, including craving that leads to relapse in human addicts. Recent studies have also revealed remarkable differences in altered ion channel activities between mPFC pyramidal neurons and medium spiny NAc neurons in cocaine-withdrawn animals. In response to psychostimulant or certain "excitatory" stimuli, increased intrinsic excitability is found in mPFC pyramidal neurons, whereas decreased excitability is observed in medium spiny NAc cells in drug-withdrawn animals compared to drug-free control animals. These changes in ion channel function are modulated by interrupted DA/Ca2+ signaling with decreased DA D2 receptor function but increased D1 receptor signaling. More importantly, they are correlated to behavioral changes in cocaine-withdrawn human addicts and sensitized animals. Based on growing evidence, researchers have proposed that cocaine-induced neuro-adaptations in ion channel activity and DA/Ca2+ signaling in mPFC pyramidal neurons and medium spiny NAc cells may be the fundamental cellular mechanism underlying the cocaine withdrawal effects observed in human addicts.

  6. Functional constraints on adaptive evolution of protein ubiquitination sites

    PubMed Central

    Lu, Liang; Li, Yang; Liu, Zhongyang; Liang, Fengji; Guo, Feifei; Yang, Shuai; Wang, Dan; He, Yangzhige; Xiong, Jianghui; Li, Dong; He, Fuchu

    2017-01-01

    It is still unclear whether there exist functional constraints on the evolution of protein ubiquitination sites, because most previous studies regarded all protein ubiquitination sites as a whole or only focused on limited structural properties. We tried to clarify the relation between functional constraints and ubiquitination sites evolution. We investigated the evolutionary conservation of human ubiquitination sites in a broad evolutionary scale from G. gorilla to S. pombe, and we found that in organisms originated after the divergence of vertebrate, ubiquitination sites are more conserved than their flanking regions, while the opposite tendency is observed before this divergence time. By grouping the ubiquitination proteins into different functional categories, we confirm that many functional constraints like certain molecular functions, protein tissue expression specificity and protein connectivity in protein-protein interaction network enhance the evolutionary conservation of ubiquitination sites. Furthermore, by analyzing the gains of ubiquitination sites at different divergence time and their functional characters, we validate that the emergences of ubiquitination sites at different evolutionary time were also affected by the uncovered functional constraints. The above results suggest that functional constraints on the adaptive evolution of ubiquitination sites increase the opportunity for ubiquitination to synthetically regulate various cellular and developmental processes during evolution. PMID:28054638

  7. Development and Adaptation of an Employment-Integration Program for People Who Are Visually Impaired in Quebec, Canada

    ERIC Educational Resources Information Center

    Wittich, Walter; Watanabe, Donald H.; Scully, Lizabeth; Bergevin , Martin

    2013-01-01

    Introduction: In the Province of Quebec, Canada, it is estimated that only about one-third of working-age adults with visual impairments are part of the workforce, despite ongoing efforts of rehabilitation and government agencies to integrate these individuals. The present article describes the development and adaptation of a pre-employment…

  8. Functional asymmetries revealed in visually guided saccades: an FMRI study.

    PubMed

    Petit, Laurent; Zago, Laure; Vigneau, Mathieu; Andersson, Frédéric; Crivello, Fabrice; Mazoyer, Bernard; Mellet, Emmanuel; Tzourio-Mazoyer, Nathalie

    2009-11-01

    Because eye movements are a fundamental tool for spatial exploration, we hypothesized that the neural bases of these movements in humans should be under right cerebral dominance, as already described for spatial attention. We used functional magnetic resonance imaging in 27 right-handed participants who alternated central fixation with either large or small visually guided saccades (VGS), equally performed in both directions. Hemispheric functional asymmetry was analyzed to identify whether brain regions showing VGS activation elicited hemispheric asymmetries. Hemispheric anatomical asymmetry was also estimated to assess its influence on the VGS functional lateralization. Right asymmetrical activations of a saccadic/attentional system were observed in the lateral frontal eye fields (FEF), the anterior part of the intraparietal sulcus (aIPS), the posterior third of the superior temporal sulcus (STS), the occipitotemporal junction (MT/V5 area), the middle occipital gyrus, and medially along the calcarine fissure (V1). The present rightward functional asymmetries were not related to differences in gray matter (GM) density/sulci positions between right and left hemispheres in the precentral, intraparietal, superior temporal, and extrastriate regions. Only V1 asymmetries were explained for almost 20% of the variance by a difference in the position of the right and left calcarine fissures. Left asymmetrical activations of a saccadic motor system were observed in the medial FEF and in the motor strip eye field along the Rolando sulcus. They were not explained by GM asymmetries. We suggest that the leftward saccadic motor asymmetry is part of a general dominance of the left motor cortex in right-handers, which must include an effect of sighting dominance. Our results demonstrate that, although bilateral by nature, the brain network involved in the execution of VGSs, irrespective of their direction, presented specific right and left asymmetries that were not related to

  9. A comparison of visual acuity, predictability, and visual function outcomes after intracorneal ring segments and laser in situ keratomileusis.

    PubMed Central

    Suiter, B G; Twa, M D; Ruckhofer, J; Schanzlin, D J

    2000-01-01

    PURPOSE: To compare correction of low myopia by intrastromal corneal ring segments (ICRS) and by laser in situ keratomileusis (LASIK) with respect to early visual recovery and refractive outcomes. METHODS: Eighty-two eyes implanted with ICRS in a phase III study for US Food and Drug Administration review were matched with 133 eyes treated with LASIK by criteria of age (> 18 years, < 65 years), preoperative myopia (-1.00 to -3.50 diopters [D]), astigmatism (< or = 1.00 D), single treatment, and attempted full correction. Examinations were performed preoperatively and postoperatively at days 1 and 7 and months 1 and 3. Visual acuity and manifest refraction data were collected retrospectively. Visual function scores were assigned, and summarized results were compared. RESULTS: Uncorrected visual acuity was 20/20 or better at day 1 in 24% of eyes (20/82) after ICRS and in 55% of eyes (73/133) after LASIK, and at month 3 in 75% of eyes (58/77) after ICRS and in 67% of eyes (84/126) after LASIK. Spherical equivalent refraction at month 3 was within +/- 1.00 D of intended correction in 99% of eyes (76/77) after ICRS and in 96% of eyes (121/126) after LASIK. Excellent visual function scores were noted at month 3 in 90% of eyes (69/77) after ICRS and in 78% of eyes (98/126) after LASIK. CONCLUSION: Patients treated with LASIK showed better uncorrected visual acuity immediately following surgery; however, beyond 1 month, patients treated with ICRS achieved better uncorrected visual acuity that continued to improve with time. Visual function scores indicate that ICRS eyes see at higher levels of uncorrected visual acuity than LASIK eyes do with the same refractive error. The ICRS and LASIK were comparable in the correction of mild myopia. PMID:11190040

  10. A Multi-facetted Visual Analytics Tool for Exploratory Analysis of Human Brain and Function Datasets

    PubMed Central

    Angulo, Diego A.; Schneider, Cyril; Oliver, James H.; Charpak, Nathalie; Hernandez, Jose T.

    2016-01-01

    Brain research typically requires large amounts of data from different sources, and often of different nature. The use of different software tools adapted to the nature of each data source can make research work cumbersome and time consuming. It follows that data is not often used to its fullest potential thus limiting exploratory analysis. This paper presents an ancillary software tool called BRAVIZ that integrates interactive visualization with real-time statistical analyses, facilitating access to multi-facetted neuroscience data and automating many cumbersome and error-prone tasks required to explore such data. Rather than relying on abstract numerical indicators, BRAVIZ emphasizes brain images as the main object of the analysis process of individuals or groups. BRAVIZ facilitates exploration of trends or relationships to gain an integrated view of the phenomena studied, thus motivating discovery of new hypotheses. A case study is presented that incorporates brain structure and function outcomes together with different types of clinical data. PMID:27601990

  11. Adaptive sigmoid function bihistogram equalization for image contrast enhancement

    NASA Astrophysics Data System (ADS)

    Arriaga-Garcia, Edgar F.; Sanchez-Yanez, Raul E.; Ruiz-Pinales, Jose; Garcia-Hernandez, Ma. de Guadalupe

    2015-09-01

    Contrast enhancement plays a key role in a wide range of applications including consumer electronic applications, such as video surveillance, digital cameras, and televisions. The main goal of contrast enhancement is to increase the quality of images. However, most state-of-the-art methods induce different types of distortion such as intensity shift, wash-out, noise, intensity burn-out, and intensity saturation. In addition, in consumer electronics, simple and fast methods are required in order to be implemented in real time. A bihistogram equalization method based on adaptive sigmoid functions is proposed. It consists of splitting the image histogram into two parts that are equalized independently by using adaptive sigmoid functions. In order to preserve the mean brightness of the input image, the parameter of the sigmoid functions is chosen to minimize the absolute mean brightness metric. Experiments on the Berkeley database have shown that the proposed method improves the quality of images and preserves their mean brightness. An application to improve the colorfulness of images is also presented.

  12. Adaptive radial basis function mesh deformation using data reduction

    NASA Astrophysics Data System (ADS)

    Gillebaart, T.; Blom, D. S.; van Zuijlen, A. H.; Bijl, H.

    2016-09-01

    Radial Basis Function (RBF) mesh deformation is one of the most robust mesh deformation methods available. Using the greedy (data reduction) method in combination with an explicit boundary correction, results in an efficient method as shown in literature. However, to ensure the method remains robust, two issues are addressed: 1) how to ensure that the set of control points remains an accurate representation of the geometry in time and 2) how to use/automate the explicit boundary correction, while ensuring a high mesh quality. In this paper, we propose an adaptive RBF mesh deformation method, which ensures the set of control points always represents the geometry/displacement up to a certain (user-specified) criteria, by keeping track of the boundary error throughout the simulation and re-selecting when needed. Opposed to the unit displacement and prescribed displacement selection methods, the adaptive method is more robust, user-independent and efficient, for the cases considered. Secondly, the analysis of a single high aspect ratio cell is used to formulate an equation for the correction radius needed, depending on the characteristics of the correction function used, maximum aspect ratio, minimum first cell height and boundary error. Based on the analysis two new radial basis correction functions are derived and proposed. This proposed automated procedure is verified while varying the correction function, Reynolds number (and thus first cell height and aspect ratio) and boundary error. Finally, the parallel efficiency is studied for the two adaptive methods, unit displacement and prescribed displacement for both the CPU as well as the memory formulation with a 2D oscillating and translating airfoil with oscillating flap, a 3D flexible locally deforming tube and deforming wind turbine blade. Generally, the memory formulation requires less work (due to the large amount of work required for evaluating RBF's), but the parallel efficiency reduces due to the limited

  13. Psychophysical measures of visual function and everyday perceptual experience in a case of congenital stationary night blindness

    PubMed Central

    Cammack, Jocelyn; Whight, John; Cross, Vinette; Rider, Andrew T; Webster, Andrew R; Stockman, Andrew

    2016-01-01

    An appreciation of the relation between laboratory measures of visual deficit and everyday perceptual experience is fundamental to understanding the impact of a visual condition on patients and so to a fuller characterization of the disorder. This study aims to understand better the interpretative processes by which modified sensory information is perceived by a patient with congenital stationary night blindness and the adaptive strategies that are devised to deal with their measurable visual loss. Psychophysical measurements of temporal resolution, spectral sensitivity, and color discrimination were conducted on a 78-year-old male patient with the condition, who was also interviewed at length about the ways in which his diagnosis affected his daily life. Narrative analysis was employed to identify the relation between his subjective perceptual experiences and functional deficits in identifiable components of the visual system. Psychophysical measurements indicated a complete lack of rod perception and substantially reduced cone sensitivity. Two particular effects of this visual loss emerged during interviews: 1) the development of navigational techniques that relied on light reflections and point sources of light and 2) a reluctance to disclose the extent of visual loss and resulting lifelong psychosocial consequences. This study demonstrates the valuable complementary role that rich descriptive patient testimony can play, in conjunction with laboratory and clinical measurements, in more fully characterizing a disorder and in reaching a more complete understanding of the experience of vision loss. It also evidences the particular suitability of filmmaking techniques as a means of accessing and communicating subjective patient experience. PMID:27601873

  14. Students with Low Vision Describe Their Visual Impairments and Visual Functioning

    ERIC Educational Resources Information Center

    Guerette, Amy R.; Lewis, Sandra; Mattingly, Cameron

    2011-01-01

    In the study reported here, the responses to a survey that was designed to determine the knowledge of their visual impairment of 51 students with low vision were analyzed. Although the students described their visual weaknesses and strengths, they had limited knowledge of, and difficulty communicating about, the medical aspects of their…

  15. Effects of visual reference on adaptation to motion sickness and subjective responses evoked by graded cross-coupled angular accelerations. [vestibular oculogravic effect in human acceleration adaptation

    NASA Technical Reports Server (NTRS)

    Reason, J. T.; Diaz, E.

    1973-01-01

    Three groups of 10 subjects each were exposed to stepwise increments of cross coupled angular accelerations in three visual modes: internal visual reference (IVR), external visual reference (EVR), and vision absent (VA). The subjects in the IVR condition required significantly greater amounts of stimulus exposure to neutralize their illusory subjective reactions. They also suffered a greater loss of well-being and a more marked incidence of motion sickness than did subjects in the EVR and VA conditions. The same 30 subjects were reexposed to the same graded cross coupled stimulation 1 week later. This time, however, all the subjects were tested under only the IVR condition. All three groups showed some positive transfer of adaptation, but only the IVR-IVR combination required significantly fewer head motions to achieve the same level of adaptation on the second occasion. Taken overall, however, the most efficient and least disturbing route to adaptation at the completion of the second test was via the VA-IVR combination.

  16. Visual function assessment and metamorphopsia after macular hole surgery.

    PubMed

    Wittich, Walter; Overbury, Olga; Kapusta, Michael A; Faubert, Jocelyn

    2005-11-01

    The purpose of this study was to develop a new resolution acuity measure for patients after macular hole surgery. Fifty eyes of 44 patients who had undergone successful treatment were tested. Visual acuity was measured with the Snellen, Early Treatment of Diabetic Retinopathy Study and Landolt-C charts. A Line Resolution Test was performed as part of their follow-up exam where a vertical line was presented. Participants were categorized by their perception of the line as solid, bent or broken. The line could be distorted into a sine-wave pattern in order to determine the participants' detection threshold for the distortion. Chart acuities did not differ among the three groups, as categorized by their line perception. Only the distortion measure was sensitive enough to differentiate the solid- from the broken-line group. The distortion measure assesses resolution power of the macula in smaller increments than acuity charts. This hyperacuity approach is more appropriate in the assessment of functional outcome after microsurgery.

  17. Visual steady state in relation to age and cognitive function.

    PubMed

    Horwitz, Anna; Dyhr Thomsen, Mia; Wiegand, Iris; Horwitz, Henrik; Klemp, Marc; Nikolic, Miki; Rask, Lene; Lauritzen, Martin; Benedek, Krisztina

    2017-01-01

    Neocortical gamma activity is crucial for sensory perception and cognition. This study examines the value of using non-task stimulation-induced EEG oscillations to predict cognitive status in a birth cohort of healthy Danish males (Metropolit) with varying cognitive ability. In particular, we examine the steady-state VEP power response (SSVEP-PR) in the alpha (8Hz) and gamma (36Hz) bands in 54 males (avg. age: 62.0 years) and compare these with 10 young healthy participants (avg. age 27.6 years). Furthermore, we correlate the individual alpha-to-gamma difference in relative visual-area power (ΔRV) with cognitive scores for the older adults. We find that ΔRV decrease with age by just over one standard deviation when comparing young with old participants (p<0.01). Furthermore, intelligence is significantly negatively correlated with ΔRV in the older adult cohort, even when processing speed, global cognition, executive function, memory, and education (p<0.05). In our preferred specification, an increase in ΔRV of one standard deviation is associated with a reduction in intelligence of 48% of a standard deviation (p<0.01). Finally, we conclude that the difference in cerebral rhythmic activity between the alpha and gamma bands is associated with age and cognitive status, and that ΔRV therefore provide a non-subjective clinical tool with which to examine cognitive status in old age.

  18. Visual steady state in relation to age and cognitive function

    PubMed Central

    Dyhr Thomsen, Mia; Wiegand, Iris; Horwitz, Henrik; Klemp, Marc; Nikolic, Miki; Rask, Lene; Lauritzen, Martin; Benedek, Krisztina

    2017-01-01

    Neocortical gamma activity is crucial for sensory perception and cognition. This study examines the value of using non-task stimulation-induced EEG oscillations to predict cognitive status in a birth cohort of healthy Danish males (Metropolit) with varying cognitive ability. In particular, we examine the steady-state VEP power response (SSVEP-PR) in the alpha (8Hz) and gamma (36Hz) bands in 54 males (avg. age: 62.0 years) and compare these with 10 young healthy participants (avg. age 27.6 years). Furthermore, we correlate the individual alpha-to-gamma difference in relative visual-area power (ΔRV) with cognitive scores for the older adults. We find that ΔRV decrease with age by just over one standard deviation when comparing young with old participants (p<0.01). Furthermore, intelligence is significantly negatively correlated with ΔRV in the older adult cohort, even when processing speed, global cognition, executive function, memory, and education (p<0.05). In our preferred specification, an increase in ΔRV of one standard deviation is associated with a reduction in intelligence of 48% of a standard deviation (p<0.01). Finally, we conclude that the difference in cerebral rhythmic activity between the alpha and gamma bands is associated with age and cognitive status, and that ΔRV therefore provide a non-subjective clinical tool with which to examine cognitive status in old age. PMID:28245274

  19. Adapting ORAP to wind plants : industry value and functional requirements.

    SciTech Connect

    Not Available

    2010-08-01

    Strategic Power Systems (SPS) was contracted by Sandia National Laboratories to assess the feasibility of adapting their ORAP (Operational Reliability Analysis Program) tool for deployment to the wind industry. ORAP for Wind is proposed for use as the primary data source for the CREW (Continuous Reliability Enhancement for Wind) database which will be maintained by Sandia to enable reliability analysis of US wind fleet operations. The report primarily addresses the functional requirements of the wind-based system. The SPS ORAP reliability monitoring system has been used successfully for over twenty years to collect RAM (Reliability, Availability, Maintainability) and operations data for benchmarking and analysis of gas and steam turbine performance. This report documents the requirements to adapt the ORAP system for the wind industry. It specifies which existing ORAP design features should be retained, as well as key new requirements for wind. The latter includes alignment with existing and emerging wind industry standards (IEEE 762, ISO 3977 and IEC 61400). There is also a comprehensive list of thirty critical-to-quality (CTQ) functional requirements which must be considered and addressed to establish the optimum design for wind.

  20. Sleep and vestibular adaptation: implications for function in microgravity

    NASA Technical Reports Server (NTRS)

    Hobson, J. A.; Stickgold, R.; Pace-Schott, E. F.; Leslie, K. R.

    1998-01-01

    Optimal human performance depends upon integrated sensorimotor and cognitive functions, both of which are known to be exquisitely sensitive to loss of sleep. Under the microgravity conditions of space flight, adaptation of both sensorimotor (especially vestibular) and cognitive functions (especially orientation) must occur quickly--and be maintained--despite any concurrent disruptions of sleep that may be caused by microgravity itself, or by the uncomfortable sleeping conditions of the spacecraft. It is the three-way interaction between sleep quality, general work efficiency, and sensorimotor integration that is the subject of this paper and the focus of new work in our laboratory. To record sleep under field conditions including microgravity, we utilize a novel system called the Nightcap that we have developed and extensively tested on normal and sleep-disordered subjects. To perturb the vestibular system in ground-based studies, we utilize a variety of experimental conditions including optokinetic stimulation and both minifying and reversing goggle paradigms that have been extensively studied in relation to plasticity of the vestibulo-ocular reflex. Using these techniques we will test the hypothesis that vestibular adaptation both provokes and is enhanced by REM sleep under both ground-based and space conditions. In this paper we describe preliminary results of some of our studies.

  1. Visualization of micro-capillaries using optical coherence tomography angiography with and without adaptive optics.

    PubMed

    Salas, Matthias; Augustin, Marco; Ginner, Laurin; Kumar, Abhishek; Baumann, Bernhard; Leitgeb, Rainer; Drexler, Wolfgang; Prager, Sonja; Hafner, Julia; Schmidt-Erfurth, Ursula; Pircher, Michael

    2017-01-01

    The purpose of this work is to investigate the benefits of adaptive optics (AO) technology for optical coherence tomography angiography (OCTA). OCTA has shown great potential in non-invasively enhancing the contrast of vessels and small capillaries. Especially the capability of the technique to visualize capillaries with a lateral extension that is below the transverse resolution of the system opens unique opportunities in diagnosing retinal vascular diseases. However, there are some limitations of this technology such as shadowing and projection artifacts caused by overlying vasculature or the inability to determine the true extension of a vessel. Thus, the evaluation of the vascular structure and density based on OCTA alone can be misleading. In this paper we compare the performance of AO-OCT, AO-OCTA and OCTA for imaging retinal vasculature. The improved transverse resolution and the reduced depth of focus of AO-OCT and AO-OCTA greatly reduce shadowing artifacts allowing for a better differentiation and segmentation of different vasculature layers of the inner retina. The comparison is done on images recorded in healthy volunteers and in diabetic patients with distinct pathologies of the retinal microvasculature.

  2. Visualization of micro-capillaries using optical coherence tomography angiography with and without adaptive optics

    PubMed Central

    Salas, Matthias; Augustin, Marco; Ginner, Laurin; Kumar, Abhishek; Baumann, Bernhard; Leitgeb, Rainer; Drexler, Wolfgang; Prager, Sonja; Hafner, Julia; Schmidt-Erfurth, Ursula; Pircher, Michael

    2016-01-01

    The purpose of this work is to investigate the benefits of adaptive optics (AO) technology for optical coherence tomography angiography (OCTA). OCTA has shown great potential in non-invasively enhancing the contrast of vessels and small capillaries. Especially the capability of the technique to visualize capillaries with a lateral extension that is below the transverse resolution of the system opens unique opportunities in diagnosing retinal vascular diseases. However, there are some limitations of this technology such as shadowing and projection artifacts caused by overlying vasculature or the inability to determine the true extension of a vessel. Thus, the evaluation of the vascular structure and density based on OCTA alone can be misleading. In this paper we compare the performance of AO-OCT, AO-OCTA and OCTA for imaging retinal vasculature. The improved transverse resolution and the reduced depth of focus of AO-OCT and AO-OCTA greatly reduce shadowing artifacts allowing for a better differentiation and segmentation of different vasculature layers of the inner retina. The comparison is done on images recorded in healthy volunteers and in diabetic patients with distinct pathologies of the retinal microvasculature. PMID:28101412

  3. An improved human visual system based reversible data hiding method using adaptive histogram modification

    NASA Astrophysics Data System (ADS)

    Hong, Wien; Chen, Tung-Shou; Wu, Mei-Chen

    2013-03-01

    Jung et al., IEEE Signal Processing Letters, 18, 2, 95, 2011 proposed a reversible data hiding method considering the human visual system (HVS). They employed the mean of visited neighboring pixels to predict the current pixel value, and estimated the just noticeable difference (JND) of the current pixel. Message bits are then embedded by adjusting the embedding level according to the calculated JND. Jung et al.'s method achieved excellent image quality. However, the embedding algorithm they used may result in over modification of pixel values and a large location map, which may deteriorate the image quality and decrease the pure payload. The proposed method exploits the nearest neighboring pixels to predict the visited pixel value and to estimate the corresponding JND. The cover pixels are preprocessed adaptively to reduce the size of the location map. We also employ an embedding level selection mechanism to prevent near-saturated pixels from being over modified. Experimental results show that the image quality of the proposed method is higher than that of Jung et al.'s method, and the payload can also be increased due to the reduction of the location map.

  4. Cardiac function adaptations in hibernating grizzly bears (Ursus arctos horribilis).

    PubMed

    Nelson, O Lynne; Robbins, Charles T

    2010-03-01

    Research on the cardiovascular physiology of hibernating mammals may provide insight into evolutionary adaptations; however, anesthesia used to handle wild animals may affect the cardiovascular parameters of interest. To overcome these potential biases, we investigated the functional cardiac phenotype of the hibernating grizzly bear (Ursus arctos horribilis) during the active, transitional and hibernating phases over a 4 year period in conscious rather than anesthetized bears. The bears were captive born and serially studied from the age of 5 months to 4 years. Heart rate was significantly different from active (82.6 +/- 7.7 beats/min) to hibernating states (17.8 +/- 2.8 beats/min). There was no difference from the active to the hibernating state in diastolic and stroke volume parameters or in left atrial area. Left ventricular volume:mass was significantly increased during hibernation indicating decreased ventricular mass. Ejection fraction of the left ventricle was not different between active and hibernating states. In contrast, total left atrial emptying fraction was significantly reduced during hibernation (17.8 +/- 2.8%) as compared to the active state (40.8 +/- 1.9%). Reduced atrial chamber function was also supported by reduced atrial contraction blood flow velocities and atrial contraction ejection fraction during hibernation; 7.1 +/- 2.8% as compared to 20.7 +/- 3% during the active state. Changes in the diastolic cardiac filling cycle, especially atrial chamber contribution to ventricular filling, appear to be the most prominent macroscopic functional change during hibernation. Thus, we propose that these changes in atrial chamber function constitute a major adaptation during hibernation which allows the myocardium to conserve energy, avoid chamber dilation and remain healthy during a period of extremely low heart rates. These findings will aid in rational approaches to identifying underlying molecular mechanisms.

  5. Detecting Visual Function Abnormality with a Contrast-Dependent Visual Test in Patients with Type 2 Diabetes.

    PubMed

    Tsai, Li-Ting; Liao, Kuo-Meng; Jang, Yuh; Hu, Fu-Chang; Wu, Wei-Chi

    2016-01-01

    In addition to diabetic retinopathy, diabetes also causes early retinal neurodegeneration and other eye problems, which cause various types of visual deficits. This study used a computer-based visual test (Macular Multi-Function Assessment (MMFA)) to assess contrast-dependent macular visual function in patients with type 2 diabetes to collect more visual information than possible with only the visual acuity test. Because the MMFA is a newly developed test, this study first compared the agreement and discriminative ability of the MMFA and the Early Treatment Diabetic Retinopathy Study (ETDRS) contrast acuity charts. Then symbol discrimination performances of diabetic patients and controls were evaluated at 4 contrast levels using the MMFA. Seventy-seven patients and 45 controls participated. The agreement between MMFA and ETDRS scores was examined by fitting three-level linear mixed-effect models to estimate the intraclass correlation coefficients (ICCs). The estimated areas under the receiver operating characteristic (ROC) curve were used to compare the discriminative ability of diseased versus non-diseased participants between the two tests. The MMFA scores of patients and controls were compared with multiple linear regression analysis after adjusting the effects of age, sex, hypertension and cataract. Results showed that the scores of the MMFA and ETDRS tests displayed high levels of agreement and acceptable and similar discriminative ability. The MMFA performance was correlated with the severity of diabetic retinopathy. Most of the MMFA scores differed significantly between the diabetic patients and controls. In the low contrast condition, the MMFA scores were significantly lower for 006Eon-DR patients than for controls. The potential utility of the MMFA as an easy screening tool for contrast-dependent visual function and for detecting early functional visual change in patients with type 2 diabetes is discussed.

  6. Detecting Visual Function Abnormality with a Contrast-Dependent Visual Test in Patients with Type 2 Diabetes

    PubMed Central

    Jang, Yuh; Hu, Fu-Chang; Wu, Wei-Chi

    2016-01-01

    In addition to diabetic retinopathy, diabetes also causes early retinal neurodegeneration and other eye problems, which cause various types of visual deficits. This study used a computer-based visual test (Macular Multi-Function Assessment (MMFA)) to assess contrast-dependent macular visual function in patients with type 2 diabetes to collect more visual information than possible with only the visual acuity test. Because the MMFA is a newly developed test, this study first compared the agreement and discriminative ability of the MMFA and the Early Treatment Diabetic Retinopathy Study (ETDRS) contrast acuity charts. Then symbol discrimination performances of diabetic patients and controls were evaluated at 4 contrast levels using the MMFA. Seventy-seven patients and 45 controls participated. The agreement between MMFA and ETDRS scores was examined by fitting three-level linear mixed-effect models to estimate the intraclass correlation coefficients (ICCs). The estimated areas under the receiver operating characteristic (ROC) curve were used to compare the discriminative ability of diseased versus non-diseased participants between the two tests. The MMFA scores of patients and controls were compared with multiple linear regression analysis after adjusting the effects of age, sex, hypertension and cataract. Results showed that the scores of the MMFA and ETDRS tests displayed high levels of agreement and acceptable and similar discriminative ability. The MMFA performance was correlated with the severity of diabetic retinopathy. Most of the MMFA scores differed significantly between the diabetic patients and controls. In the low contrast condition, the MMFA scores were significantly lower for 006Eon-DR patients than for controls. The potential utility of the MMFA as an easy screening tool for contrast-dependent visual function and for detecting early functional visual change in patients with type 2 diabetes is discussed. PMID:27611680

  7. Executive functioning and adaptive coping in healthy adults.

    PubMed

    Rodríguez Villegas, Ana Lilia; Salvador Cruz, Judith

    2015-01-01

    Middle-aged individuals encounter multiple environmental demands to which they must develop efficient solutions, thus making the study of executive functions and coping strategies within this age group important. This study evaluated the relationship between the planning and flexible organization of executive function with adaptive coping strategies (ACS) in adults aged 43 to 52 years old. The study included 104 participants, including 52 men and 52 women, with no history of neurological or psychiatric illnesses, diabetes, or hypertension. The participants engaged in the Tower of London(DX) (TOL(DX)) test, the Wisconsin Card-Sorting Test (WCST), and the Coping Strategies Inventory. A relationship was observed between the percentage of errors and conceptual-level responses (WCST) and the Problem Solving ACS. In a separate analysis performed on the men, a negative relationship was discovered between the WCST and the Emotional Expression ACS. In the female group, the dimensions of the WCST and the TOL(DX) were associated with the ACS Emotional Expression and Problem-Solving subscales and the maladaptive coping strategy Social Withdrawal subscale. The relationship between executive functioning and the ACS is multidimensional, complex, and different between men and women. This study adds a neuropsychological characterization of the relationship between executive functions and ACS with ecological validity. The study confirms a relationship between the flexible organization of executive function and the Problem-Solving ACS.

  8. Here, there and everywhere: higher visual function and the dorsal visual stream.

    PubMed

    Cooper, Sarah Anne; O'Sullivan, Michael

    2016-06-01

    The dorsal visual stream, often referred to as the 'where' stream, represents the pathway taken by visual information from the primary visual cortex to the posterior parietal lobe and onwards. It partners the ventral or 'what' stream, the subject of a previous review and largely a temporal-based system. Here, we consider the dorsal stream disorders of perception (simultanagnosia, akinetopsia) along with their consequences on action (eg, optic ataxia and oculomotor apraxia, along with Balint's syndrome). The role of the dorsal stream in blindsight and hemispatial neglect is also considered.

  9. The OTOLITH Experiment - Assessment of Otolith Function During Postflight Re-adaption

    NASA Technical Reports Server (NTRS)

    Clarke, A. H.; Wood, S. J.; Schoenfeld, U.

    2010-01-01

    The ongoing "Otolith" experiment is designed to comprehensively assess the otolith function during the re-adaptation phase after spaceflight. The novel protocol includes unilateral testing of each of the two otolith organs the utricle and the saccule. To assess utricle function, the otolith-ocular response (OOR) and the subjective visual vertical (SVV) are measured during unilateral centrifugation, which permits independent stimulation of the right and left ear. Measurement of the unilateral otolith-ocular response (uOOR) yields information on the response behaviour of the right and left peripheral utricles, whereas the SVV reflects the behaviour of the entire pathway from the peripheral otolith receptors to the vestibular cortex. Thus, by comparative evaluation of the results from the two tests, the degree of peripheral versus central adaptation during the post-flight period can be determined. To assess unilateral saccule function, vestibular evoked myogenic potentials (VEMP) are recorded. Since the saccules are predominantly aligned to gravity, and interplay with the antigravity muscles, it is hypothesised that these potentials shall be altered after spaceflight. To date the study has been conducted with 5 of a planned 8 short-flight Shuttle astronauts. Preliminary results will be discussed together with those from clinical studies of dizziness patients, where the same test protocol is employed. ACKNOWLEDGEMENT This work is supported by the German Aerospace Center (Grant DLR W130729) and is conducted under the auspices of ESA, in cooperation with NASA.

  10. Fundamental Visual Representations of Social Cognition in ASD

    DTIC Science & Technology

    2015-10-01

    ERPs) has revealed atypical visual adaptation functions in Autism, again pointing to basic sensory processing anomalies in this population. Our...visual maps in the often challenging-to-test ASD pediatric population. 15. SUBJECT TERMS Autism, Visual Adaptation , Retinotopy, Social Communication...sensory adaptation functions in the hierarchically early regions of the visual processing hierarchy in ASD. The second details our work to establish

  11. Visual adaptation of the perception of “life”: animacy is a basic perceptual dimension of faces

    PubMed Central

    Koldewyn, Kami; Hanus, Patricia; Balas, Benjamin

    2014-01-01

    One critical component of understanding another’s mind is the perception of “life” in a face. However, little is known about the cognitive and neural mechanisms underlying this perception of animacy. Here, using a visual adaptation paradigm, we ask whether face animacy is (1) a basic dimension of face perception and (2) supported by a common neural mechanism across distinct face categories defined by age and species. Observers rated the perceived animacy of adult human faces before and after adaptation to (1) adult faces, (2) child faces, and (3) dog faces. When testing the perception of animacy in human faces, we found significant adaptation to both adult and child faces, but not dog faces. We did, however, find significant adaptation when morphed dog images and dog adaptors were used. Thus, animacy perception in faces appears to be a basic dimension of face perception that is species-specific, but not constrained by age categories. PMID:24323739

  12. Seeing the sound after visual loss: functional MRI in acquired auditory-visual synesthesia.

    PubMed

    Yong, Zixin; Hsieh, Po-Jang; Milea, Dan

    2017-02-01

    Acquired auditory-visual synesthesia (AVS) is a rare neurological sign, in which specific auditory stimulation triggers visual experience. In this study, we used event-related fMRI to explore the brain regions correlated with acquired monocular sound-induced phosphenes, which occurred 2 months after unilateral visual loss due to an ischemic optic neuropathy. During the fMRI session, 1-s pure tones at various pitches were presented to the patient, who was asked to report occurrence of sound-induced phosphenes by pressing one of the two buttons (yes/no). The brain activation during phosphene-experienced trials was contrasted with non-phosphene trials and compared to results obtained in one healthy control subject who underwent the same fMRI protocol. Our results suggest, for the first time, that acquired AVS occurring after visual impairment is associated with bilateral activation of primary and secondary visual cortex, possibly due to cross-wiring between auditory and visual sensory modalities.

  13. Structural and functional correlates of visual field asymmetry in the human brain by diffusion kurtosis MRI and functional MRI.

    PubMed

    O'Connell, Caitlin; Ho, Leon C; Murphy, Matthew C; Conner, Ian P; Wollstein, Gadi; Cham, Rakie; Chan, Kevin C

    2016-11-09

    Human visual performance has been observed to show superiority in localized regions of the visual field across many classes of stimuli. However, the underlying neural mechanisms remain unclear. This study aims to determine whether the visual information processing in the human brain is dependent on the location of stimuli in the visual field and the corresponding neuroarchitecture using blood-oxygenation-level-dependent functional MRI (fMRI) and diffusion kurtosis MRI, respectively, in 15 healthy individuals at 3 T. In fMRI, visual stimulation to the lower hemifield showed stronger brain responses and larger brain activation volumes than the upper hemifield, indicative of the differential sensitivity of the human brain across the visual field. In diffusion kurtosis MRI, the brain regions mapping to the lower visual field showed higher mean kurtosis, but not fractional anisotropy or mean diffusivity compared with the upper visual field. These results suggested the different distributions of microstructural organization across visual field brain representations. There was also a strong positive relationship between diffusion kurtosis and fMRI responses in the lower field brain representations. In summary, this study suggested the structural and functional brain involvements in the asymmetry of visual field responses in humans, and is important to the neurophysiological and psychological understanding of human visual information processing.

  14. Context-dependent adaptation of visually-guided arm movements and vestibular eye movements: role of the cerebellum

    NASA Technical Reports Server (NTRS)

    Lewis, Richard F.

    2003-01-01

    Accurate motor control requires adaptive processes that correct for gradual and rapid perturbations in the properties of the controlled object. The ability to quickly switch between different movement synergies using sensory cues, referred to as context-dependent adaptation, is a subject of considerable interest at present. The potential function of the cerebellum in context-dependent adaptation remains uncertain, but the data reviewed below suggest that it may play a fundamental role in this process.

  15. Correlation between visual function, neurodevelopmental outcome, and magnetic resonance imaging findings in infants with periventricular leucomalacia

    PubMed Central

    Cioni, G.; Bertuccelli, B.; Boldrini, A.; Canapicchi, R.; Fazzi, B.; Guzzetta, A.; Mercuri, E.

    2000-01-01

    AIM—To evaluate the correlation between visual function and neurodevelopmental outcome in children with periventricular leucomalacia at 1 and 3years.
METHOD—Visual acuity, visual field, ocular motility, and optokinetic nystagmus were tested in 29 infants with periventricular leucomalacia by brain magnetic resonance imaging. All infants also had a structured neurological examination and a Griffiths developmental assessment.
RESULTS—21 of the infants showed at least one abnormality of visual function. The degree of visual impairment—that is, the number of visual tests showing abnormal results—correlated well with the results on developmental assessment at both ages.
CONCLUSION—Multivariate analysis showed that visual impairment was the most important variable in determining the neurodevelopmental scores of these infants, more than their motor disability and the extent of their lesions on magnetic resonance imaging.

 PMID:10685987

  16. Functional modules of sigma factor regulons guarantee adaptability and evolvability

    PubMed Central

    Binder, Sebastian C.; Eckweiler, Denitsa; Schulz, Sebastian; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Häussler, Susanne; Meyer-Hermann, Michael

    2016-01-01

    The focus of modern molecular biology turns from assigning functions to individual genes towards understanding the expression and regulation of complex sets of molecules. Here, we provide evidence that alternative sigma factor regulons in the pathogen Pseudomonas aeruginosa largely represent insulated functional modules which provide a critical level of biological organization involved in general adaptation and survival processes. Analysis of the operational state of the sigma factor network revealed that transcription factors functionally couple the sigma factor regulons and significantly modulate the transcription levels in the face of challenging environments. The threshold quality of newly evolved transcription factors was reached faster and more robustly in in silico testing when the structural organization of sigma factor networks was taken into account. These results indicate that the modular structures of alternative sigma factor regulons provide P. aeruginosa with a robust framework to function adequately in its environment and at the same time facilitate evolutionary change. Our data support the view that widespread modularity guarantees robustness of biological networks and is a key driver of evolvability. PMID:26915971

  17. Functional modules of sigma factor regulons guarantee adaptability and evolvability

    NASA Astrophysics Data System (ADS)

    Binder, Sebastian C.; Eckweiler, Denitsa; Schulz, Sebastian; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Häussler, Susanne; Meyer-Hermann, Michael

    2016-02-01

    The focus of modern molecular biology turns from assigning functions to individual genes towards understanding the expression and regulation of complex sets of molecules. Here, we provide evidence that alternative sigma factor regulons in the pathogen Pseudomonas aeruginosa largely represent insulated functional modules which provide a critical level of biological organization involved in general adaptation and survival processes. Analysis of the operational state of the sigma factor network revealed that transcription factors functionally couple the sigma factor regulons and significantly modulate the transcription levels in the face of challenging environments. The threshold quality of newly evolved transcription factors was reached faster and more robustly in in silico testing when the structural organization of sigma factor networks was taken into account. These results indicate that the modular structures of alternative sigma factor regulons provide P. aeruginosa with a robust framework to function adequately in its environment and at the same time facilitate evolutionary change. Our data support the view that widespread modularity guarantees robustness of biological networks and is a key driver of evolvability.

  18. Resting-state functional connectivity predicts longitudinal change in autistic traits and adaptive functioning in autism

    PubMed Central

    Plitt, Mark; Barnes, Kelly Anne; Wallace, Gregory L.; Kenworthy, Lauren; Martin, Alex

    2015-01-01

    Although typically identified in early childhood, the social communication symptoms and adaptive behavior deficits that are characteristic of autism spectrum disorder (ASD) persist throughout the lifespan. Despite this persistence, even individuals without cooccurring intellectual disability show substantial heterogeneity in outcomes. Previous studies have found various behavioral assessments [such as intelligence quotient (IQ), early language ability, and baseline autistic traits and adaptive behavior scores] to be predictive of outcome, but most of the variance in functioning remains unexplained by such factors. In this study, we investigated to what extent functional brain connectivity measures obtained from resting-state functional connectivity MRI (rs-fcMRI) could predict the variance left unexplained by age and behavior (follow-up latency and baseline autistic traits and adaptive behavior scores) in two measures of outcome—adaptive behaviors and autistic traits at least 1 y postscan (mean follow-up latency = 2 y, 10 mo). We found that connectivity involving the so-called salience network (SN), default-mode network (DMN), and frontoparietal task control network (FPTCN) was highly predictive of future autistic traits and the change in autistic traits and adaptive behavior over the same time period. Furthermore, functional connectivity involving the SN, which is predominantly composed of the anterior insula and the dorsal anterior cingulate, predicted reliable improvement in adaptive behaviors with 100% sensitivity and 70.59% precision. From rs-fcMRI data, our study successfully predicted heterogeneity in outcomes for individuals with ASD that was unaccounted for by simple behavioral metrics and provides unique evidence for networks underlying long-term symptom abatement. PMID:26627261

  19. Resting-state functional connectivity predicts longitudinal change in autistic traits and adaptive functioning in autism.

    PubMed

    Plitt, Mark; Barnes, Kelly Anne; Wallace, Gregory L; Kenworthy, Lauren; Martin, Alex

    2015-12-01

    Although typically identified in early childhood, the social communication symptoms and adaptive behavior deficits that are characteristic of autism spectrum disorder (ASD) persist throughout the lifespan. Despite this persistence, even individuals without cooccurring intellectual disability show substantial heterogeneity in outcomes. Previous studies have found various behavioral assessments [such as intelligence quotient (IQ), early language ability, and baseline autistic traits and adaptive behavior scores] to be predictive of outcome, but most of the variance in functioning remains unexplained by such factors. In this study, we investigated to what extent functional brain connectivity measures obtained from resting-state functional connectivity MRI (rs-fcMRI) could predict the variance left unexplained by age and behavior (follow-up latency and baseline autistic traits and adaptive behavior scores) in two measures of outcome--adaptive behaviors and autistic traits at least 1 y postscan (mean follow-up latency = 2 y, 10 mo). We found that connectivity involving the so-called salience network (SN), default-mode network (DMN), and frontoparietal task control network (FPTCN) was highly predictive of future autistic traits and the change in autistic traits and adaptive behavior over the same time period. Furthermore, functional connectivity involving the SN, which is predominantly composed of the anterior insula and the dorsal anterior cingulate, predicted reliable improvement in adaptive behaviors with 100% sensitivity and 70.59% precision. From rs-fcMRI data, our study successfully predicted heterogeneity in outcomes for individuals with ASD that was unaccounted for by simple behavioral metrics and provides unique evidence for networks underlying long-term symptom abatement.

  20. Executive Function and Behavioral Problems in Students with Visual Impairments at Mainstream and Special Schools

    ERIC Educational Resources Information Center

    Heyl, Vera; Hintermair, Manfred

    2015-01-01

    Introduction: In this study, executive function of school-aged children with visual impairments (that is, those who are blind or have low vision) is examined in the context of behavioral problems and communicative competence. Methods: Teachers assessed the executive function of a sample of 226 visually impaired students from mainstream schools and…

  1. Cognitive and Perceptual Functions of the Visual Thalamus

    PubMed Central

    Saalmann, Yuri B.; Kastner, Sabine

    2011-01-01

    The thalamus is classically viewed as passively relaying information to the cortex. However, there is growing evidence that the thalamus actively regulates information transmission to the cortex and between cortical areas using a variety of mechanisms, including the modulation of response magnitude, firing mode and synchrony of neurons according to behavioral demands. We discuss how the visual thalamus contributes to attention, awareness and visually-guided actions, to present a general role for the thalamus in perception and cognition. PMID:21791281

  2. Site and Orbit Repeatabilities using Adaptive Mapping Functions

    NASA Astrophysics Data System (ADS)

    Desjardins, Camille; Gegout, Pascal; Soudarin, Laurent; Biancale, Richard; Perosanz, Felix

    2015-04-01

    The electromagnetic signals emitted by the satellite positioning systems travel at the speed of light in a straight line in a vacuum but are modified in their propagation through the neutral atmosphere by temporal and spatial changes of density, and composition and refractivity. These waves are slowed down and their trajectories are bent. This presentation summarizes the performances of the modeling of the tropospheric propagation by the ray tracing technique through the assimilations of the European Meteorological Centre (ECMWF) in the framework of realizing the geodetic reference frame. This goal is achieved by modeling the spatial variability of the propagation using the time variable three-dimensional physical parameters of the atmosphere. The tropospheric delays obtained by ray tracing in all directions throughout the meteorological model surrounding the geodetic site, are fitted by Adaptive Mapping Functions (AMF) parameterized by several tens of coefficients. The delays produced by the Horizon software are then experimented, kept unchanged or adjusted, when recovering a reference frame based on hundred sites using the GINS software. Without any adjustments of the tropospheric modeling, the subcentimetric performances of the AMF are demonstrated by the repeatability of sites positions and GPS satellites orbits. When some AMF coefficients are adjusted, the accuracy of orbits recovery in term of quadratic mean is 7 to 8 millimeters. This limit is imposed by the lack or deficiency of other models, such as non-tidal and tidal loading respectively. Hence the repeatability of the vertical position is not enhanced by changing the propagation model. At the contrary, the repeatability of the horizontal position of geodetic sites is greatly enhanced by accounting for the azimuthal variability provided by the realistic 3D shapes of the Atmosphere and the Earth and the rigorous interpolations of atmospheric parameters included in Adaptive Mapping Functions with respect

  3. Adapting the Crossmodal Congruency Task for Measuring the Limits of Visual-Tactile Interactions Within and Between Groups.

    PubMed

    Poole, Daniel; Couth, Samuel; Gowen, Emma; Warren, Paul A; Poliakoff, Ellen

    2015-01-01

    The crossmodal congruency task (CCT) is a commonly used paradigm for measuring visual-tactile interactions and how these may be influenced by discrepancies in space and time between the tactile target and visual distractors. The majority of studies which have used this paradigm have neither measured, nor attempted to control, individual variability in unisensory (tactile) performance. We have developed a version of the CCT in which unisensory baseline performance is constrained to enable comparisons within and between participant groups. Participants were instructed to discriminate between single and double tactile pulses presented to their dominant hand, at their own approximate threshold level. In Experiment 1, visual distractors were presented at -30 ms, 100 ms, 200 ms and 400 ms stimulus onset asynchronies. In Experiment 2, ipsilateral visual distractors were presented 0 cm, 21 cm, and 42 cm vertically from the target hand, and 42 cm in a symmetrical, contralateral position. Distractors presented -30 ms and 0 cm from the target produced a significantly larger congruency effect than at other time points and spatial locations. Thus, the typical limits of visual-tactile interactions were replicated using a version of the task in which baseline performance can be constrained. The usefulness of this approach is supported by the observation that tactile thresholds correlated with self-reported autistic traits in this non-clinical sample. We discuss the suitability of this adapted version of the CCT for measuring visual-tactile interactions in populations where unisensory tactile ability may differ within and between groups.

  4. Adaptive Optics Analysis of Visual Benefit with Higher-order Aberrations Correction of Human Eye - Poster Paper

    NASA Astrophysics Data System (ADS)

    Xue, Lixia; Dai, Yun; Rao, Xuejun; Wang, Cheng; Hu, Yiyun; Liu, Qian; Jiang, Wenhan

    2008-01-01

    Higher-order aberrations correction can improve visual performance of human eye to some extent. To evaluate how much visual benefit can be obtained with higher-order aberrations correction we developed an adaptive optics vision simulator (AOVS). Dynamic real time optimized modal compensation was used to implement various customized higher-order ocular aberrations correction strategies. The experimental results indicate that higher-order aberrations correction can improve visual performance of human eye comparing with only lower-order aberration correction but the improvement degree and higher-order aberration correction strategy are different from each individual. Some subjects can acquire great visual benefit when higher-order aberrations were corrected but some subjects acquire little visual benefit even though all higher-order aberrations were corrected. Therefore, relative to general lower-order aberrations correction strategy, customized higher-order aberrations correction strategy is needed to obtain optimal visual improvement for each individual. AOVS provides an effective tool for higher-order ocular aberrations optometry for customized ocular aberrations correction.

  5. Function-valued adaptive dynamics and optimal control theory.

    PubMed

    Parvinen, Kalle; Heino, Mikko; Dieckmann, Ulf

    2013-09-01

    In this article we further develop the theory of adaptive dynamics of function-valued traits. Previous work has concentrated on models for which invasion fitness can be written as an integral in which the integrand for each argument value is a function of the strategy value at that argument value only. For this type of models of direct effect, singular strategies can be found using the calculus of variations, with singular strategies needing to satisfy Euler's equation with environmental feedback. In a broader, more mechanistically oriented class of models, the function-valued strategy affects a process described by differential equations, and fitness can be expressed as an integral in which the integrand for each argument value depends both on the strategy and on process variables at that argument value. In general, the calculus of variations cannot help analyzing this much broader class of models. Here we explain how to find singular strategies in this class of process-mediated models using optimal control theory. In particular, we show that singular strategies need to satisfy Pontryagin's maximum principle with environmental feedback. We demonstrate the utility of this approach by studying the evolution of strategies determining seasonal flowering schedules.

  6. GATA-3 function in innate and adaptive immunity.

    PubMed

    Tindemans, Irma; Serafini, Nicolas; Di Santo, James P; Hendriks, Rudi W

    2014-08-21

    The zinc-finger transcription factor GATA-3 has received much attention as a master regulator of T helper 2 (Th2) cell differentiation, during which it controls interleukin-4 (IL-4), IL-5, and IL-13 expression. More recently, GATA-3 was shown to contribute to type 2 immunity through regulation of group 2 innate lymphoid cell (ILC2) development and function. Furthermore, during thymopoiesis, GATA-3 represses B cell potential in early T cell precursors, activates TCR signaling in pre-T cells, and promotes the CD4(+) T cell lineage after positive selection. GATA-3 also functions outside the thymus in hematopoietic stem cells, regulatory T cells, CD8(+) T cells, thymic natural killer cells, and ILC precursors. Here we discuss the varied functions of GATA-3 in innate and adaptive immune cells, with emphasis on its activity in T cells and ILCs, and examine the mechanistic basis for the dose-dependent, developmental-stage- and cell-lineage-specific activity of this transcription factor.

  7. Improved visualization of outer retinal morphology with aberration cancelling reflective optical design for adaptive optics - optical coherence tomography

    PubMed Central

    Lee, Sang-Hyuck; Werner, John S.; Zawadzki, Robert J.

    2013-01-01

    We present an aberration cancelling optical design for a reflective adaptive optics - optical coherence tomography (AO-OCT) retinal imaging system. The optical performance of this instrument is compared to our previous multimodal AO-OCT/AO-SLO retinal imaging system. The feasibility of new instrumentation for improved visualization of microscopic retinal structures is discussed. Examples of images acquired with this new AO-OCT instrument are presented. PMID:24298411

  8. Evolution under pressure and the adaptation of visual pigment compressibility in deep-sea environments.

    PubMed

    Porter, Megan L; Roberts, Nicholas W; Partridge, Julian C

    2016-12-01

    Understanding the link between how proteins function in animals that live in extreme environments and selection on specific properties of amino acids has proved extremely challenging. Here we present the discovery of how the compressibility of opsin proteins in two evolutionarily distinct animal groups, teleosts and cephalopods, appears to be adapted to the high-pressure environment of the deep-sea. We report how in both groups, opsins in deeper living species are calculated to be less compressible. This is largely due to a common set of amino acid sites (bovRH# 159, 196, 213, 275) undergoing positive destabilizing selection in six of the twelve amino acid physiochemical properties that determine protein compressibility. This suggests a common evolutionary mechanism to reduce the adiabatic compressibility of opsin proteins. Intriguingly, the sites under selection are on the proteins' outer faces at locations known to be involved in opsin-opsin dimer interactions.

  9. Visual attention as an important visual function: an outline of manifestations, diagnosis and management of impaired visual attention

    PubMed Central

    Das, Meghomala; Bennett, David M; Dutton, Gordon N

    2007-01-01

    Impaired visual attention is a common manifestation of cerebral dysfunction. In adults, closed head trauma, cerebral microvascular ischaemia and dementia are common causes. In children, aetiologies include periventricular leukomalacia, hydrocephalus, hypoxic ischaemic encephalopathy and brain damage caused by hypoglycaemia. The resultant visual disability can be profound even when visual acuities are unaffected, and can cause significant disability in the execution of daily activities. This can prompt consultation with an eye care specialist. Patients complain of poor vision, difficulty in identifying someone in a group, or finding an object on a patterned background or among other objects, but a thorough examination often does not reveal the clinical basis for these complaints. The diagnosis of attentional dysfunction is also easily missed because at present it can only be recognised on the basis of adequate history taking from both the patient and close relatives and friends. The Useful Field of View test facilitates the detection and quantification of this disorder. Management includes the implementation of strategies that diminish background pattern and foreground clutter. PMID:17301124

  10. The visual corticostriatal loop through the tail of the caudate: circuitry and function

    PubMed Central

    Seger, Carol A.

    2013-01-01

    Although high level visual cortex projects to a specific region of the striatum, the tail of the caudate, and participates in corticostriatal loops, the function of this visual corticostriatal system is not well understood. This article first reviews what is known about the anatomy of the visual corticostriatal loop across mammals, including rodents, cats, monkeys, and humans. Like other corticostriatal systems, the visual corticostriatal system includes both closed loop components (recurrent projections that return to the originating cortical location) and open loop components (projections that terminate in other neural regions). The article then reviews what previous empirical research has shown about the function of the tail of the caudate. The article finally addresses the possible functions of the closed and open loop connections of the visual loop in the context of theories and computational models of corticostriatal function. PMID:24367300

  11. Executive functions as predictors of visual-motor integration in children with intellectual disability.

    PubMed

    Memisevic, Haris; Sinanovic, Osman

    2013-12-01

    The goal of this study was to assess the relationship between visual-motor integration and executive functions, and in particular, the extent to which executive functions can predict visual-motor integration skills in children with intellectual disability. The sample consisted of 90 children (54 boys, 36 girls; M age = 11.3 yr., SD = 2.7, range 7-15) with intellectual disabilities of various etiologies. The measure of executive functions were 8 subscales of the Behavioral Rating Inventory of Executive Function (BRIEF) consisting of Inhibition, Shifting, Emotional Control, Initiating, Working memory, Planning, Organization of material, and Monitoring. Visual-motor integration was measured with the Acadia test of visual-motor integration (VMI). Regression analysis revealed that BRIEF subscales explained 38% of the variance in VMI scores. Of all the BRIEF subscales, only two were statistically significant predictors of visual-motor integration: Working memory and Monitoring. Possible implications of this finding are further elaborated.

  12. Disturbance of visual functions as a result of temporary blinding from low power lasers

    NASA Astrophysics Data System (ADS)

    Reidenbach, Hans-Dieter

    2010-04-01

    Although it is well-known that dazzle, flash-blindness and afterimages may be caused by bright optical radiation, only sparse quantitative data are available with regard to the effects arising from low power laser products. Indirect effects like temporary blinding might result in serious incidents or even accidents due to the alteration of visual functions like visual acuity, contrast sensitivity and color discrimination. In order to determine the degree and duration of impairment resulting from dazzle, flash-blindness and afterimages, caused by a laser beam, an investigation has been performed with the goal to improve the current knowledge as far as especially the visual acuity recovery duration is concerned. Two different test set-ups were designed and applied in order to determine the afterimage duration and the recovery time for visual acuity after temporary blinding from a laser, respectively. In order to get the desired information a helium-neon laser was mounted on a movable assembly where the respective beam position and direction could be set up on a semicircle. In addition the mount could be inclined in a vertical plane in order to increase the variability of feasible settings. The power was adjusted in several steps in order to investigate the respective dependence of the afterimage. The investigations were relatively time consuming, since re-adaptation of about half an hour was necessary after every exposure in order not to falsify the results. The trials have been done with several volunteers in the laboratory. After the experimental mapping of the local afterimage duration for the various sites on the retina the foveal afterimage duration taf,fv produced by a red laser beam was determined. The investigations have shown a strong dependence on the angle between the line of sight and the beam direction. Besides a maximum of 300 s the dose relationship taf,fv/s ~ 50.6•ln[(P•texp)/μJ] - 13.4 for laser output powers P between 10 μW and 30 μW with

  13. Adaptive functional diversification of lysozyme in insectivorous bats.

    PubMed

    Liu, Yang; He, Guimei; Xu, Huihui; Han, Xiuqun; Jones, Gareth; Rossiter, Stephen J; Zhang, Shuyi

    2014-11-01

    The role of gene duplication in generating new genes and novel functions is well recognized and is exemplified by the digestion-related protein lysozyme. In ruminants, duplicated chicken-type lysozymes facilitate the degradation of symbiotic bacteria in the foregut. Chicken-type lysozyme has also been reported to show chitinase-like activity, yet no study has examined the molecular evolution of lysozymes in species that specialize on eating insects. Insectivorous bats number over 900 species, and lysozyme expression in the mouths of some of these species is associated with the ingestion of insect cuticle, suggesting a chitinase role. Here, we show that chicken-type lysozyme has undergone multiple duplication events in a major family of insect-eating bats (Vespertilionidae) and that new duplicates have undergone molecular adaptation. Examination of duplicates from two insectivorous bats-Pipistrellus abramus and Scotophilus kuhlii-indicated that the new copy was highly expressed in the tongue, whereas the other one was less tissue-specific. Functional assays applied to pipistrelle lysozymes confirmed that, of the two copies, the tongue duplicate was more efficient at breaking down glycol chitin, a chitin derivative. These results suggest that the evolution of lysozymes in vespertilionid bats has likely been driven in part by natural selection for insectivory.

  14. Diabetes reduces the cognitive function with the decrease of the visual perception and visual motor integration in male older adults.

    PubMed

    Yun, Hyo-Soon; Kim, Eunhwi; Suh, Soon-Rim; Kim, Mi-Han; Kim, Hong

    2013-01-01

    This study investigated the influence of diabetes on cognitive decline between the diabetes and non- diabetes patients and identified the associations between diabetes and cognitive function, visual perception (VP), and visual motor integration (VMI). Sixty elderly men (67.10± 1.65 yr) with and without diabetes (n= 30 in each group) who were surveyed by interview and questionnaire in South Korea were enrolled in this study. The score of Mini-Mental State Examination of Korean version (MMSE-KC), Motor-free Visual Perception Test-Vertical Format (MVPT-V), and Visual-Motor Integration 3rd Revision (VMI-3R) were assessed in all of the participants to evaluate cognitive function, VP, and VMI in each. The score of MMSE-KC in the diabetic group was significantly lower than that of the non-diabetes group (P< 0.01). Participants in the diabetes group also had lower MVPT-V and VMI-3R scores than those in the non-diabetes group (P< 0.01, respectively). Especially, the scores of figure-ground and visual memory among the subcategories of MVPT-V were significantly lower in the diabetes group than in the non-diabetes group (P< 0.01). These findings indicate that the decline in cognitive function in individuals with diabetes may be greater than that in non-diabetics. In addition, the cognitive decline in older adults with diabetes might be associated with the decrease of VP and VMI. In conclusion, we propose that VP and VMI will be helpful to monitor the change of cognitive function in older adults with diabetes as part of the routine management of diabetes-induced cognitive declines.

  15. Advancing Creative Visual Thinking with Constructive Function-Based Modelling

    ERIC Educational Resources Information Center

    Pasko, Alexander; Adzhiev, Valery; Malikova, Evgeniya; Pilyugin, Victor

    2013-01-01

    Modern education technologies are destined to reflect the realities of a modern digital age. The juxtaposition of real and synthetic (computer-generated) worlds as well as a greater emphasis on visual dimension are especially important characteristics that have to be taken into account in learning and teaching. We describe the ways in which an…

  16. Perceptual Visual Grouping under Inattention: Electrophysiological Functional Imaging

    ERIC Educational Resources Information Center

    Razpurker-Apfeld, Irene; Pratt, Hillel

    2008-01-01

    Two types of perceptual visual grouping, differing in complexity of shape formation, were examined under inattention. Fourteen participants performed a similarity judgment task concerning two successive briefly presented central targets surrounded by task-irrelevant simple and complex grouping patterns. Event-related potentials (ERPs) were…

  17. Clinical Assessment of Functional Movement in Adults with Visual Impairments

    ERIC Educational Resources Information Center

    Ray, Christopher T.; Horvat, Michael; Williams, Michael; Blasch, Bruce B.

    2007-01-01

    Adults with visual impairments have significantly more health risks than do sighted adults because of a number of factors, including the lower mineral density of their femoral neck bones, which is indicative of reduced weight-bearing exercise; their lesser maximal strength; and their higher rates of stroke, osteoporosis, depression, hypertension,…

  18. Functional brain organization of preparatory attentional control in visual search.

    PubMed

    Bourke, Patrick; Brown, Steven; Ngan, Elton; Liotti, Mario

    2013-09-12

    Looking for an object that may be present in a cluttered visual display requires an advanced specification of that object to be created and then matched against the incoming visual input. Here, fast event-related fMRI was used to identify the brain networks that are active when preparing to search for a visual target. By isolating the preparation phase of the task it has been possible to show that for an identical stimulus, different patterns of cortical activation occur depending on whether participants anticipate a 'feature' or a 'conjunction' search task. When anticipating a conjunction search task, there was more robust activation in ventral occipital areas, new activity in the transverse occipital sulci and right posterior intraparietal sulcus. In addition, preparing for either type of search activated ventral striatum and lateral cerebellum. These results suggest that when participants anticipate a demanding search task, they develop a different advanced representation of a visually identical target stimulus compared to when they anticipate a nondemanding search.

  19. The relationship between visual acuity and functioning and well-being among diabetics.

    PubMed

    Lee, P P; Whitcup, S M; Hays, R D; Spritzer, K; Javitt, J

    1995-08-01

    Given the enormous recent interest in functional capabilities related to vision, the goal of this study was to examine the relationship of standard clinical measures of vision (e.g. Snellen acuity) to functioning and well-being. The association between Snellen visual acuity, Amsler grid distortion and presence of diabetic retinopathy with self-reported functioning and well-being (SF-36) were examined in a sample of 327 diabetics from the Medical Outcomes Study (MOS). There was little or no correlation between Snellen visual acuity, Amsler grid distortion or diabetic retinopathy and functioning and well-being (i.e. SF-36 scales). Maximum product-moment correlation was 0.15 with worst eye visual acuity, 0.13 with best eye visual acuity, 0.08 with presence of retinopathy, and 0.10 with Amsler grid distortion. Analysis of variance revealed that visual acuity (both best and worst eye) was statistically related only to the physical function scale; no other exam measure was related to any other SF-36 scale score. Snellen visual acuity, Amsler distortion and diabetic retinopathy correlate weakly with patient self-reported functioning and well-being. Thus, the information provided by functioning and well-being measures is complementary to that of standard clinical measures of visual ability.

  20. Impaired functional differentiation for categories of objects in the ventral visual stream: A case of developmental visual impairment.

    PubMed

    Martinaud, Olivier; Pouliquen, Dorothée; Parain, Dominique; Goldenberg, Alice; Gérardin, Emmanuel; Hannequin, Didier; Altarelli, Irène; Ramus, Franck; Hertz-Pannier, Lucie; Dehaene-Lambertz, Ghislaine; Cohen, Laurent

    2015-10-01

    We report the case of a 14-year-old girl suffering from severe developmental visual impairment along with delayed language and cognitive development, and featuring a clear-cut dissociation between spared dorsal and impaired ventral visual pathways. Visual recognition of objects, including faces and printed words, was affected. In contrast, movement perception and visually guided motor control were preserved. Structural MRI was normal on inspection, but Voxel Based Morphometry (VBM) revealed reduced grey matter density in the mesial occipital and ventral occipito-temporal cortex. Functional MRI during the perception of line drawings uncovered impaired differentiation which is normally observed at even younger ages: no local category preferences could be identified within the occipito-temporal cortex for faces, houses, words or tools. In contrast, movement-related activations appeared to be normal. Finally, those abnormalities evolved on the background of chronic bilateral occipital epileptic activity, including continuous spike-wave discharges during sleep, which may be considered as the primary cause of non-specific intellectual disability and visual impairment.

  1. 3D functional ultrasound imaging of the cerebral visual system in rodents.

    PubMed

    Gesnik, Marc; Blaize, Kevin; Deffieux, Thomas; Gennisson, Jean-Luc; Sahel, José-Alain; Fink, Mathias; Picaud, Serge; Tanter, Mickaël

    2017-02-03

    3D functional imaging of the whole brain activity during visual task is a challenging task in rodents due to the complex tri-dimensional shape of involved brain regions and the fine spatial and temporal resolutions required to reveal the visual tract. By coupling functional ultrasound (fUS) imaging with a translational motorized stage and an episodic visual stimulation device, we managed to accurately map and to recover the activity of the visual cortices, the Superior Colliculus (SC) and the Lateral Geniculate Nuclei (LGN) in 3D. Cerebral Blood Volume (CBV) responses during visual stimuli were found to be highly correlated with the visual stimulus time profile in visual cortices (r=0.6), SC (r=0.7) and LGN (r=0.7). These responses were found dependent on flickering frequency and contrast, and optimal stimulus parameters for largest CBV increases were obtained. In particular, increasing the flickering frequency higher than 7Hz revealed a decrease of visual cortices response while the SC response was preserved. Finally, cross-correlation between CBV signals exhibited significant delays (d=0.35s +/-0.1s) between blood volume response in SC and visual cortices in response to our visual stimulus. These results emphasize the interest of fUS imaging as a whole brain neuroimaging modality for brain vision studies in rodent models.

  2. Visualization of Time-Series Sensor Data to Inform the Design of Just-In-Time Adaptive Stress Interventions

    PubMed Central

    Sharmin, Moushumi; Raij, Andrew; Epstien, David; Nahum-Shani, Inbal; Beck, J. Gayle; Vhaduri, Sudip; Preston, Kenzie; Kumar, Santosh

    2015-01-01

    We investigate needs, challenges, and opportunities in visualizing time-series sensor data on stress to inform the design of just-in-time adaptive interventions (JITAIs). We identify seven key challenges: massive volume and variety of data, complexity in identifying stressors, scalability of space, multifaceted relationship between stress and time, a need for representation at multiple granularities, interperson variability, and limited understanding of JITAI design requirements due to its novelty. We propose four new visualizations based on one million minutes of sensor data (n=70). We evaluate our visualizations with stress researchers (n=6) to gain first insights into its usability and usefulness in JITAI design. Our results indicate that spatio-temporal visualizations help identify and explain between- and within-person variability in stress patterns and contextual visualizations enable decisions regarding the timing, content, and modality of intervention. Interestingly, a granular representation is considered informative but noise-prone; an abstract representation is the preferred starting point for designing JITAIs. PMID:26539566

  3. Highly adaptive tests for group differences in brain functional connectivity.

    PubMed

    Kim, Junghi; Pan, Wei

    2015-01-01

    Resting-state functional magnetic resonance imaging (rs-fMRI) and other technologies have been offering evidence and insights showing that altered brain functional networks are associated with neurological illnesses such as Alzheimer's disease. Exploring brain networks of clinical populations compared to those of controls would be a key inquiry to reveal underlying neurological processes related to such illnesses. For such a purpose, group-level inference is a necessary first step in order to establish whether there are any genuinely disrupted brain subnetworks. Such an analysis is also challenging due to the high dimensionality of the parameters in a network model and high noise levels in neuroimaging data. We are still in the early stage of method development as highlighted by Varoquaux and Craddock (2013) that "there is currently no unique solution, but a spectrum of related methods and analytical strategies" to learn and compare brain connectivity. In practice the important issue of how to choose several critical parameters in estimating a network, such as what association measure to use and what is the sparsity of the estimated network, has not been carefully addressed, largely because the answers are unknown yet. For example, even though the choice of tuning parameters in model estimation has been extensively discussed in the literature, as to be shown here, an optimal choice of a parameter for network estimation may not be optimal in the current context of hypothesis testing. Arbitrarily choosing or mis-specifying such parameters may lead to extremely low-powered tests. Here we develop highly adaptive tests to detect group differences in brain connectivity while accounting for unknown optimal choices of some tuning parameters. The proposed tests combine statistical evidence against a null hypothesis from multiple sources across a range of plausible tuning parameter values reflecting uncertainty with the unknown truth. These highly adaptive tests are not only

  4. Highly adaptive tests for group differences in brain functional connectivity

    PubMed Central

    Kim, Junghi; Pan, Wei

    2015-01-01

    Resting-state functional magnetic resonance imaging (rs-fMRI) and other technologies have been offering evidence and insights showing that altered brain functional networks are associated with neurological illnesses such as Alzheimer's disease. Exploring brain networks of clinical populations compared to those of controls would be a key inquiry to reveal underlying neurological processes related to such illnesses. For such a purpose, group-level inference is a necessary first step in order to establish whether there are any genuinely disrupted brain subnetworks. Such an analysis is also challenging due to the high dimensionality of the parameters in a network model and high noise levels in neuroimaging data. We are still in the early stage of method development as highlighted by Varoquaux and Craddock (2013) that “there is currently no unique solution, but a spectrum of related methods and analytical strategies” to learn and compare brain connectivity. In practice the important issue of how to choose several critical parameters in estimating a network, such as what association measure to use and what is the sparsity of the estimated network, has not been carefully addressed, largely because the answers are unknown yet. For example, even though the choice of tuning parameters in model estimation has been extensively discussed in the literature, as to be shown here, an optimal choice of a parameter for network estimation may not be optimal in the current context of hypothesis testing. Arbitrarily choosing or mis-specifying such parameters may lead to extremely low-powered tests. Here we develop highly adaptive tests to detect group differences in brain connectivity while accounting for unknown optimal choices of some tuning parameters. The proposed tests combine statistical evidence against a null hypothesis from multiple sources across a range of plausible tuning parameter values reflecting uncertainty with the unknown truth. These highly adaptive tests are not

  5. SOS mutator DNA polymerase IV functions in adaptive mutation and not adaptive amplification.

    PubMed

    McKenzie, G J; Lee, P L; Lombardo, M J; Hastings, P J; Rosenberg, S M

    2001-03-01

    Adaptive point mutation and amplification are induced responses to environmental stress, promoting genetic changes that can enhance survival. A specialized adaptive mutation mechanism has been documented in one Escherichia coli assay, but its enzymatic basis remained unclear. We report that the SOS-inducible, error-prone DNA polymerase (pol) IV, encoded by dinB, is required for adaptive point mutation in the E. coli lac operon. A nonpolar dinB mutation reduces adaptive mutation frequencies by 85% but does not affect adaptive amplification, growth-dependent mutation, or survival after oxidative or UV damage. We show that pol IV, together with the major replicase, pol III, can account for all adaptive point mutations at lac. The results identify a role for pol IV in inducible genetic change.

  6. Relationship between macular pigment and visual function in subjects with early age-related macular degeneration

    PubMed Central

    Nolan, John M; Peto, Tunde; Stack, Jim; Leung, Irene; Corcoran, Laura; Beatty, Stephen

    2017-01-01

    Purpose To investigate the relationship between macular pigment (MP) and visual function in subjects with early age-related macular degeneration (AMD). Methods 121 subjects with early AMD enrolled as part of the Central Retinal Enrichment Supplementation Trial (CREST; ISRCTN13894787) were assessed using a range of psychophysical measures of visual function, including best corrected visual acuity (BCVA), letter contrast sensitivity (CS), mesopic and photopic CS, mesopic and photopic glare disability (GD), photostress recovery time (PRT), reading performance and subjective visual function, using the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). MP was measured using customised heterochromatic flicker photometry. Results Letter CS, mesopic and photopic CS, photopic GD and mean reading speed were each significantly (p<0.05) associated with MP across a range of retinal eccentricities, and these statistically significant relationships persisted after controlling for age, sex and cataract grade. BCVA, NEI VFQ-25 score, PRT and mesopic GD were unrelated to MP after controlling for age, sex and cataract grade (p>0.05, for all). Conclusions MP relates positively to many measures of visual function in unsupplemented subjects with early AMD. The CREST trial will investigate whether enrichment of MP influences visual function among those afflicted with this condition. Trial registration number ISRCTN13894787. PMID:27091854

  7. Seeing the Light: Adapting Luminance Reveals Low-Level Visual Processes in the Attentional Blink

    ERIC Educational Resources Information Center

    Giesbrecht, Barry; Bischof, Walter F.; Kingstone, Alan

    2004-01-01

    It is widely assumed that high-level visual processes subserve the attentional blink (AB). Recent evidence from studies of visual masking during the AB that were designed to directly test the contributions of high-level masking effects, however, have failed to provide empirical support for this position.The implication is that low-level visual…

  8. Adapting Artworks for People Who Are Blind or Visually Impaired Using Raised Printing

    ERIC Educational Resources Information Center

    Krivec, Tjaša; Muck, Tadeja; Germadnik, Rolanda Fugger; Majnaric, Igor; Golob, Gorazd

    2014-01-01

    Everyone has the right to freely participate in the cultural life of the community (United Nations, 2012). In Europe and around the globe, many efforts have been made in order to include people with visual impairments and blindness into the cultural life. The objects and artifacts exhibited in museums for people with visual impairments are…

  9. The cost of misremembering: Inferring the loss function in visual working memory.

    PubMed

    Sims, Chris R

    2015-03-04

    Visual working memory (VWM) is a highly limited storage system. A basic consequence of this fact is that visual memories cannot perfectly encode or represent the veridical structure of the world. However, in natural tasks, some memory errors might be more costly than others. This raises the intriguing possibility that the nature of memory error reflects the costs of committing different kinds of errors. Many existing theories assume that visual memories are noise-corrupted versions of afferent perceptual signals. However, this additive noise assumption oversimplifies the problem. Implicit in the behavioral phenomena of visual working memory is the concept of a loss function: a mathematical entity that describes the relative cost to the organism of making different types of memory errors. An optimally efficient memory system is one that minimizes the expected loss according to a particular loss function, while subject to a constraint on memory capacity. This paper describes a novel theoretical framework for characterizing visual working memory in terms of its implicit loss function. Using inverse decision theory, the empirical loss function is estimated from the results of a standard delayed recall visual memory experiment. These results are compared to the predicted behavior of a visual working memory system that is optimally efficient for a previously identified natural task, gaze correction following saccadic error. Finally, the approach is compared to alternative models of visual working memory, and shown to offer a superior account of the empirical data across a range of experimental datasets.

  10. Simple exponential functions describing the absorbance bands of visual pigment spectra.

    PubMed

    Stavenga, D G; Smits, R P; Hoenders, B J

    1993-05-01

    Literature data for visual pigment spectra are formally treated by assuming that the spectra consist of a summation of absorbance bands, that the shape of the bands is invariant according to the Mansfield-MacNichol transform and that this shape is described by simple exponential functions. A new template for constructing visual pigment spectra from peak wavelengths is derived.

  11. Protein reconstitution methods for visualizing biomolecular function in living cells.

    PubMed

    Ozawa, Takeaki

    2009-03-01

    One of the most challenging researches in current biology and medicinal chemistry is to understand how individual cellular molecules interact together in living cells. To visualize such molecules, genetically-encoded reporters have been used widely. The most common reporters are firefly luciferase, renilla luciferase, green fluorescent protein (GFP) and its variants with various spectral properties. In this review, novel design of split GFP and split luciferase is described. The principle is based on reconstitution of the split-reporter fragments when they are brought together into close proximity. The reconstitution methods are used for screening organelle-localized proteins, imaging dynamics of nuclear proteins and mRNAs in living cells, and visualizing protease activities in living animals. These methods are generally applicable for imaging of complex cellular processes and evaluating chemical effects in living cells and animals.

  12. Night vision in barn owls: visual acuity and contrast sensitivity under dark adaptation.

    PubMed

    Orlowski, Julius; Harmening, Wolf; Wagner, Hermann

    2012-12-06

    Barn owls are effective nocturnal predators. We tested their visual performance at low light levels and determined visual acuity and contrast sensitivity of three barn owls by their behavior at stimulus luminances ranging from photopic to fully scotopic levels (23.5 to 1.5 × 10⁻⁶). Contrast sensitivity and visual acuity decreased only slightly from photopic to scotopic conditions. Peak grating acuity was at mesopic (4 × 10⁻² cd/m²) conditions. Barn owls retained a quarter of their maximal acuity when luminance decreased by 5.5 log units. We argue that the visual system of barn owls is designed to yield as much visual acuity under low light conditions as possible, thereby sacrificing resolution at photopic conditions.

  13. Functional connectivity patterns reflect individual differences in conflict adaptation.

    PubMed

    Wang, Xiangpeng; Wang, Ting; Chen, Zhencai; Hitchman, Glenn; Liu, Yijun; Chen, Antao

    2015-04-01

    Individuals differ in the ability to utilize previous conflict information to optimize current conflict resolution, which is termed the conflict adaptation effect. Previous studies have linked individual differences in conflict adaptation to distinct brain regions. However, the network-based neural mechanisms subserving the individual differences of the conflict adaptation effect have not been studied. The present study employed a psychophysiological interaction (PPI) analysis with a color-naming Stroop task to examine this issue. The main results were as follows: (1) the anterior cingulate cortex (ACC)-seeded PPI revealed the involvement of the salience network (SN) in conflict adaptation, while the posterior parietal cortex (PPC)-seeded PPI revealed the engagement of the central executive network (CEN). (2) Participants with high conflict adaptation effect showed higher intra-CEN connectivity and lower intra-SN connectivity; while those with low conflict adaptation effect showed higher intra-SN connectivity and lower intra-CEN connectivity. (3) The PPC-centered intra-CEN connectivity positively predicted the conflict adaptation effect; while the ACC-centered intra-SN connectivity had a negative correlation with this effect. In conclusion, our data demonstrated that conflict adaptation is likely supported by the CEN and the SN, providing a new perspective on studying individual differences in conflict adaptation on the basis of large-scale networks.

  14. Predictors and Correlates of Adaptive Functioning in Children with Developmental Disorders.

    ERIC Educational Resources Information Center

    Liss, Miriam; Harel, Brian; Fein, Deborah; Allen, Doris; Dunn, Michelle; Feinstein, Carl; Morris, Robin; Waterhouse, Lynn; Rapin, Isabel

    2001-01-01

    A study involving 35 children (age 9) with high-functioning autism, 31 children with developmental language disorder, 40 children with low-functioning autism, and 17 children with low IQ, found IQ was predictive of adaptive behavior in both low-functioning groups, but language and verbal memory predicted adaptive behavior in higher functioning…

  15. Assessing Adaptive Functioning in Preschoolers Referred for Diagnosis of Developmental Disabilities

    ERIC Educational Resources Information Center

    Milne, Susan; McDonald, Jenny

    2015-01-01

    Adaptive function is an essential dimension in the diagnosis of neurodevelopmental conditions in young children, assisting in determining the pattern of intellectual function and the amount and type of support required. Yet, little information is available on the accuracy of currently used adaptive function assessments for preschool children. This…

  16. Point spread function determination for Keck adaptive optics

    NASA Astrophysics Data System (ADS)

    Ragland, S.; Jolissaint, L.; Wizinowich, P.; van Dam, M. A.; Mugnier, L.; Bouxin, A.; Chock, J.; Kwok, S.; Mader, J.; Witzel, G.; Do, Tuan; Fitzgerald, M.; Ghez, A.; Lu, J.; Martinez, G.; Morris, M. R.; Sitarski, B.

    2016-07-01

    One of the primary scientific limitations of adaptive optics (AO) has been the incomplete knowledge of the point spread function (PSF), which has made it difficult to use AO for accurate photometry and astrometry in both crowded and sparse fields, for extracting intrinsic morphologies and spatially resolved kinematics, and for detecting faint sources in the presence of brighter sources. To address this limitation, we initiated a program to determine and demonstrate PSF reconstruction for science observations obtained with Keck AO. This paper aims to give a broad view of the progress achieved in implementing a PSF reconstruction capability for Keck AO science observations. This paper describes the implementation of the algorithms, and the design and development of the prototype operational tools for automated PSF reconstruction. On-sky performance is discussed by comparing the reconstructed PSFs to the measured PSF's on the NIRC2 science camera. The importance of knowing the control loop performance, accurate mapping of the telescope pupil to the deformable mirror and the science instrument pupil, and the telescope segment piston error are highlighted. We close by discussing lessons learned and near-term future plans.

  17. Applying Utility Functions to Adaptation Planning for Home Automation Applications

    NASA Astrophysics Data System (ADS)

    Bratskas, Pyrros; Paspallis, Nearchos; Kakousis, Konstantinos; Papadopoulos, George A.

    A pervasive computing environment typically comprises multiple embedded devices that may interact together and with mobile users. These users are part of the environment, and they experience it through a variety of devices embedded in the environment. This perception involves technologies which may be heterogeneous, pervasive, and dynamic. Due to the highly dynamic properties of such environments, the software systems running on them have to face problems such as user mobility, service failures, or resource and goal changes which may happen in an unpredictable manner. To cope with these problems, such systems must be autonomous and self-managed. In this chapter we deal with a special kind of a ubiquitous environment, a smart home environment, and introduce a user-preference-based model for adaptation planning. The model, which dynamically forms a set of configuration plans for resources, reasons automatically and autonomously, based on utility functions, on which plan is likely to best achieve the user's goals with respect to resource availability and user needs.

  18. Feasibility and Preliminary Efficacy of Visual Cue Training to Improve Adaptability of Walking after Stroke: Multi-Centre, Single-Blind Randomised Control Pilot Trial

    PubMed Central

    Hollands, Kristen L.; Pelton, Trudy A.; Wimperis, Andrew; Whitham, Diane; Tan, Wei; Jowett, Sue; Sackley, Catherine M.; Wing, Alan M.; Tyson, Sarah F.; Mathias, Jonathan; Hensman, Marianne; van Vliet, Paulette M.

    2015-01-01

    Objectives Given the importance of vision in the control of walking and evidence indicating varied practice of walking improves mobility outcomes, this study sought to examine the feasibility and preliminary efficacy of varied walking practice in response to visual cues, for the rehabilitation of walking following stroke. Design This 3 arm parallel, multi-centre, assessor blind, randomised control trial was conducted within outpatient neurorehabilitation services Participants Community dwelling stroke survivors with walking speed <0.8m/s, lower limb paresis and no severe visual impairments Intervention Over-ground visual cue training (O-VCT), Treadmill based visual cue training (T-VCT), and Usual care (UC) delivered by physiotherapists twice weekly for 8 weeks. Main outcome measures: Participants were randomised using computer generated random permutated balanced blocks of randomly varying size. Recruitment, retention, adherence, adverse events and mobility and balance were measured before randomisation, post-intervention and at four weeks follow-up. Results Fifty-six participants participated (18 T-VCT, 19 O-VCT, 19 UC). Thirty-four completed treatment and follow-up assessments. Of the participants that completed, adherence was good with 16 treatments provided over (median of) 8.4, 7.5 and 9 weeks for T-VCT, O-VCT and UC respectively. No adverse events were reported. Post-treatment improvements in walking speed, symmetry, balance and functional mobility were seen in all treatment arms. Conclusions Outpatient based treadmill and over-ground walking adaptability practice using visual cues are feasible and may improve mobility and balance. Future studies should continue a carefully phased approach using identified methods to improve retention. Trial Registration Clinicaltrials.gov NCT01600391 PMID:26445137

  19. Normal Visual Acuity and Electrophysiological Contrast Gain in Adults with High-Functioning Autism Spectrum Disorder

    PubMed Central

    Tebartz van Elst, Ludger; Bach, Michael; Blessing, Julia; Riedel, Andreas; Bubl, Emanuel

    2015-01-01

    A common neurodevelopmental disorder, autism spectrum disorder (ASD), is defined by specific patterns in social perception, social competence, communication, highly circumscribed interests, and a strong subjective need for behavioral routines. Furthermore, distinctive features of visual perception, such as markedly reduced eye contact and a tendency to focus more on small, visual items than on holistic perception, have long been recognized as typical ASD characteristics. Recent debate in the scientific community discusses whether the physiology of low-level visual perception might explain such higher visual abnormalities. While reports of this enhanced, “eagle-like” visual acuity contained methodological errors and could not be substantiated, several authors have reported alterations in even earlier stages of visual processing, such as contrast perception and motion perception at the occipital cortex level. Therefore, in this project, we have investigated the electrophysiology of very early visual processing by analyzing the pattern electroretinogram-based contrast gain, the background noise amplitude, and the psychophysical visual acuities of participants with high-functioning ASD and controls with equal education. Based on earlier findings, we hypothesized that alterations in early vision would be present in ASD participants. This study included 33 individuals with ASD (11 female) and 33 control individuals (12 female). The groups were matched in terms of age, gender, and education level. We found no evidence of altered electrophysiological retinal contrast processing or psychophysical measured visual acuities. There appears to be no evidence for abnormalities in retinal visual processing in ASD patients, at least with respect to contrast detection. PMID:26379525

  20. Basic visual function and cortical thickness patterns in posterior cortical atrophy.

    PubMed

    Lehmann, Manja; Barnes, Josephine; Ridgway, Gerard R; Wattam-Bell, John; Warrington, Elizabeth K; Fox, Nick C; Crutch, Sebastian J

    2011-09-01

    Posterior cortical atrophy (PCA) is characterized by a progressive decline in higher-visual object and space processing, but the extent to which these deficits are underpinned by basic visual impairments is unknown. This study aimed to assess basic and higher-order visual deficits in 21 PCA patients. Basic visual skills including form detection and discrimination, color discrimination, motion coherence, and point localization were measured, and associations and dissociations between specific basic visual functions and measures of higher-order object and space perception were identified. All participants showed impairment in at least one aspect of basic visual processing. However, a number of dissociations between basic visual skills indicated a heterogeneous pattern of visual impairment among the PCA patients. Furthermore, basic visual impairments were associated with particular higher-order object and space perception deficits, but not with nonvisual parietal tasks, suggesting the specific involvement of visual networks in PCA. Cortical thickness analysis revealed trends toward lower cortical thickness in occipitotemporal (ventral) and occipitoparietal (dorsal) regions in patients with visuoperceptual and visuospatial deficits, respectively. However, there was also a lot of overlap in their patterns of cortical thinning. These findings suggest that different presentations of PCA represent points in a continuum of phenotypical variation.

  1. Second Graders Learn Animal Adaptations through Form and Function Analogy Object Boxes

    ERIC Educational Resources Information Center

    Rule, Audrey C.; Baldwin, Samantha; Schell, Robert

    2008-01-01

    This study examined the use of form and function analogy object boxes to teach second graders (n = 21) animal adaptations. The study used a pretest-posttest design to examine animal adaptation content learned through focused analogy activities as compared with reading and Internet searches for information about adaptations of animals followed by…

  2. Identifying Differential Item Functioning in Multi-Stage Computer Adaptive Testing

    ERIC Educational Resources Information Center

    Gierl, Mark J.; Lai, Hollis; Li, Johnson

    2013-01-01

    The purpose of this study is to evaluate the performance of CATSIB (Computer Adaptive Testing-Simultaneous Item Bias Test) for detecting differential item functioning (DIF) when items in the matching and studied subtest are administered adaptively in the context of a realistic multi-stage adaptive test (MST). MST was simulated using a 4-item…

  3. Design and test of a Microsoft Kinect-based system for delivering adaptive visual feedback to stroke patients during training of upper limb movement.

    PubMed

    Simonsen, Daniel; Popovic, Mirjana B; Spaich, Erika G; Andersen, Ole Kæseler

    2017-03-25

    The present paper describes the design and test of a low-cost Microsoft Kinect-based system for delivering adaptive visual feedback to stroke patients during the execution of an upper limb exercise. Eleven sub-acute stroke patients with varying degrees of upper limb function were recruited. Each subject participated in a control session (repeated twice) and a feedback session (repeated twice). In each session, the subjects were presented with a rectangular pattern displayed on a vertical mounted monitor embedded in the table in front of the patient. The subjects were asked to move a marker inside the rectangular pattern by using their most affected hand. During the feedback session, the thickness of the rectangular pattern was changed according to the performance of the subject, and the color of the marker changed according to its position, thereby guiding the subject's movements. In the control session, the thickness of the rectangular pattern and the color of the marker did not change. The results showed that the movement similarity and smoothness was higher in the feedback session than in the control session while the duration of the movement was longer. The present study showed that adaptive visual feedback delivered by use of the Kinect sensor can increase the similarity and smoothness of upper limb movement in stroke patients.

  4. Out of the blue: adaptive visual pigment evolution accompanies Amazon invasion.

    PubMed

    Van Nynatten, Alexander; Bloom, Devin; Chang, Belinda S W; Lovejoy, Nathan R

    2015-07-01

    Incursions of marine water into South America during the Miocene prompted colonization of freshwater habitats by ancestrally marine species and present a unique opportunity to study the molecular evolution of adaptations to varying environments. Freshwater and marine environments are distinct in both spectra and average intensities of available light. Here, we investigate the molecular evolution of rhodopsin, the photosensitive pigment in the eye that activates in response to light, in a clade of South American freshwater anchovies derived from a marine ancestral lineage. Using likelihood-based comparative sequence analyses, we found evidence for positive selection in the rhodopsin of freshwater anchovy lineages at sites known to be important for aspects of rhodopsin function such as spectral tuning. No evidence was found for positive selection in marine lineages, nor in three other genes not involved in vision. Our results suggest that an increased rate of rhodopsin evolution was driven by diversification into freshwater habitats, thereby constituting a rare example of molecular evolution mirroring large-scale palaeogeographic events.

  5. Separate channels for processing form, texture, and color: evidence from FMRI adaptation and visual object agnosia.

    PubMed

    Cavina-Pratesi, C; Kentridge, R W; Heywood, C A; Milner, A D

    2010-10-01

    Previous neuroimaging research suggests that although object shape is analyzed in the lateral occipital cortex, surface properties of objects, such as color and texture, are dealt with in more medial areas, close to the collateral sulcus (CoS). The present study sought to determine whether there is a single medial region concerned with surface properties in general or whether instead there are multiple foci independently extracting different surface properties. We used stimuli varying in their shape, texture, or color, and tested healthy participants and 2 object-agnosic patients, in both a discrimination task and a functional MR adaptation paradigm. We found a double dissociation between medial and lateral occipitotemporal cortices in processing surface (texture or color) versus geometric (shape) properties, respectively. In Experiment 2, we found that the medial occipitotemporal cortex houses separate foci for color (within anterior CoS and lingual gyrus) and texture (caudally within posterior CoS). In addition, we found that areas selective for shape, texture, and color individually were quite distinct from those that respond to all of these features together (shape and texture and color). These latter areas appear to correspond to those associated with the perception of complex stimuli such as faces and places.

  6. Visual-motor and executive functions in children born preterm: the Bender Visual Motor Gestalt Test revisited.

    PubMed

    Böhm, Birgitta; Lundequist, Aiko; Smedler, Ann-Charlotte

    2010-10-01

    Visual-motor development and executive functions were investigated with the Bender Test at age 5½ years in 175 children born preterm and 125 full-term controls, within the longitudinal Stockholm Neonatal Project. Assessment also included WPPSI-R and NEPSY neuropsychological battery for ages 4-7 (Korkman, 1990). Bender protocols were scored according to Brannigan & Decker (2003), Koppitz (1963) and a complementary neuropsychological scoring system (ABC), aimed at executive functions and developed for this study. Bender results by all three scoring systems were strongly related to overall cognitive level (Performance IQ), in both groups. The preterm group displayed inferior visual-motor skills compared to controls also when controlling for IQ. The largest group differences were found on the ABC scoring, which shared unique variance with NEPSY tests of executive function. Multiple regression analyses showed that hyperactive behavior and inattention increased the risk for visual-motor deficits in children born preterm, whereas no added risk was seen among hyperactive term children. Gender differences favoring girls were strongest within the preterm group, presumably reflecting the specific vulnerability of preterm boys. The results indicate that preterm children develop a different neurobehavioral organization from children born at term, and that the Bender test with a neuropsychological scoring is a useful tool in developmental screening around school start.

  7. Visualizing and Tracking Evolving Features in 3D Unstructured and Adaptive Datasets

    SciTech Connect

    Silver, D.; Zabusky, N.

    2002-08-01

    The massive amounts of time-varying datasets being generated demand new visualization and quantification techniques. Visualization alone is not sufficient. Without proper measurement information/computations real science cannot be done. Our focus is this work was to combine visualization with quantification of the data to allow for advanced querying and searching. As part of this proposal, we have developed a feature extraction adn tracking methodology which allows researcher to identify features of interest and follow their evolution over time. The implementation is distributed and operates over data In-situ: where it is stored and when it was computed.

  8. Age and Adaptive Functioning in Children and Adolescents with ASD: The Effects of Intellectual Functioning and ASD Symptom Severity

    PubMed Central

    Hill, Trenesha L.; Gray, Sarah A. O.; Kamps, Jodi L.; Varela, R. Enrique

    2016-01-01

    The present study examined the moderating effects of intellectual functioning and ASD symptom severity on the relation between age and adaptive functioning in 220 youth with autism spectrum disorder (ASD). Regression analysis indicated that intellectual functioning and ASD symptom severity moderated the relation between age and adaptive functioning. For younger children with lower intellectual functioning, higher ASD symptom severity was associated with better adaptive functioning than that of those with lower ASD symptom severity. Similarly, for older children with higher intellectual functioning, higher ASD symptom severity was associated with better adaptive functioning than that of those with lower ASD symptom severity. Analyses by subscales suggest that this pattern is driven by the Conceptual subscale. Clinical and research implications are discussed. PMID:26174048

  9. Age and Adaptive Functioning in Children and Adolescents with ASD: The Effects of Intellectual Functioning and ASD Symptom Severity.

    PubMed

    Hill, Trenesha L; Gray, Sarah A O; Kamps, Jodi L; Enrique Varela, R

    2015-12-01

    The present study examined the moderating effects of intellectual functioning and ASD symptom severity on the relation between age and adaptive functioning in 220 youth with autism spectrum disorder (ASD). Regression analysis indicated that intellectual functioning and ASD symptom severity moderated the relation between age and adaptive functioning. For younger children with lower intellectual functioning, higher ASD symptom severity was associated with better adaptive functioning than that of those with lower ASD symptom severity. Similarly, for older children with higher intellectual functioning, higher ASD symptom severity was associated with better adaptive functioning than that of those with lower ASD symptom severity. Analyses by subscales suggest that this pattern is driven by the Conceptual subscale. Clinical and research implications are discussed.

  10. Assessing Adaptive Functioning in Death Penalty Cases after Hall and DSM-5.

    PubMed

    Hagan, Leigh D; Drogin, Eric Y; Guilmette, Thomas J

    2016-03-01

    DSM-5 and Hall v. Florida (2014) have dramatically refocused attention on the assessment of adaptive functioning in death penalty cases. In this article, we address strategies for assessing the adaptive functioning of defendants who seek exemption from capital punishment pursuant to Atkins v. Virginia (2002). In particular, we assert that evaluations of adaptive functioning should address assets as well as deficits; seek to identify credible and reliable evidence concerning the developmental period and across the lifespan; distinguish incapacity from the mere absence of adaptive behavior; adhere faithfully to test manual instructions for using standardized measures of adaptive functioning; and account for potential bias on the part of informants. We conclude with brief caveats regarding the standard error of measurement (SEM) in light of Hall, with reference to examples of ordinary life activities that directly illuminate adaptive functioning relevant to capital cases.

  11. Effects of visual fatigue caused by smartphones on balance function in healthy adults

    PubMed Central

    Park, Young-Hyun; An, Chang-Man; Moon, Sung-Jun

    2017-01-01

    [Purpose] The purpose of this study was to determine the effects of visual fatigue caused by smartphone use on balance function. [Subjects and Methods] The participants consisted of 22 healthy male and female adults. Their postural stability, limit of stability, and limit of stability running time were evaluated using a computerized posturography apparatus before and after inducing visual fatigue. Postural stability and the limit of stability were divided into static and dynamic conditions. [Results] There were significant differences between the dynamic postural stability, the static and dynamic limit of stability, and both the static and dynamic limit of stability running times after the induction of visual fatigue. [Conclusion] The results showed that visual fatigue caused by smartphone use has a negative effect on balance function. Therefore, reducing visual fatigue through proper rest is necessary. PMID:28265143

  12. Development of a Preference-Based Index from the National Eye Institute Visual Function Questionnaire-25

    PubMed Central

    Rentz, Anne M.; Kowalski, Jonathan W.; Walt, John G.; Hays, Ron D.; Brazier, John E.; Yu, Ren; Lee, Paul; Bressler, Neil; Revicki, Dennis A.

    2015-01-01

    Importance Understanding how individuals value health states is central to patient-centered care and to health policy decision making. Generic preference-based measures of health may not effectively capture the impact of ocular diseases. Recently, 6 items from the National Eye Institute Visual Function Questionnaire-25 were used to develop the Visual Function Questionnaire-Utility Index health state classification, which defines visual function health states. Objective To describe elicitation of preferences for health states generated from the Visual Function Questionnaire-Utility Index health state classification and development of an algorithm to estimate health preference scores for any health state. Design Non-intervention, cross-sectional study. Setting General community in four countries (Australia, Canada, United Kingdom, and United States) Participants 607 adult participants recruited from local newspaper advertisements. In the United Kingdom, an existing database of participants from previous studies was used for recruitment. Interventions Eight out of 15,625 possible health states from the Visual Function Questionnaire-Utility Index were valued using time trade-off technique. Main Outcome Measures A theta severity score was calculated for Visual Function Questionnaire-Utility Index–defined health states using item response theory analysis. Regression models were then used to develop an algorithm to assign health state preference values for all potential health states defined by the Visual Function Questionnaire-Utility Index. Results Health state preference values for the 8 states ranged from 0.343 (standard deviation, 0.395) to 0.956 (0.124). As expected, preference values declined with worsening visual function. Results indicate that the Visual Function Questionnaire-Utility Index describes states that participants view as spanning most of continuum from full health to dead. Conclusions and Relevance Visual Function Questionnaire-Utility Index health

  13. A social ecological approach to investigating relationships between housing and adaptive functioning for persons with serious mental illness.

    PubMed

    Kloos, Bret; Shah, Seema

    2009-12-01

    This paper seeks to advance mental health-housing research regarding which factors of housing and neighborhood environments are critical for adaptive functioning, health, and recovery for persons with serious mental illness (SMI). Housing and neighborhood environments are particularly important for persons with SMI because of the prevalence of poor housing conditions among this population. Most mental health-housing research has been limited by a focus on problems in environments and functioning. The paper seeks to expand the mental health-housing research agenda to consider protective factors that promote community integration and adaptive functioning. We provide an account of how social ecology theory transformed a research program, from examining individual risk factors to investigating the functioning of persons in the contexts of their housing and neighborhood experiences. The resulting housing environment framework-physical aspects of housing and neighborhoods, social environment of neighborhoods, and interpersonal relationships tied to housing-allows for identification of opportunities for health promotion and facilitation of participation in community-based settings. This program of research draws upon several methods to understand the social experience of persons with SMI living in community settings-survey research, qualitative interviews, Geographic Information Systems, participatory research, and visual ethnography. In this paper, we present how social ecology theory was instrumental in the development of new housing environment measures, the selection of appropriate research methods, and framing research questions that are building a new empirical base of knowledge about promoting adaptive functioning, health, and recovery for persons with SMI living in community settings.

  14. Functional magnetic resonance adaptation reveals the involvement of the dorsomedial stream in hand orientation for grasping.

    PubMed

    Monaco, Simona; Cavina-Pratesi, Cristiana; Sedda, Anna; Fattori, Patrizia; Galletti, Claudio; Culham, Jody C

    2011-11-01

    Reach-to-grasp actions require coordination of different segments of the upper limbs. Previous studies have examined the neural substrates of arm transport and hand grip components of such actions; however, a third component has been largely neglected: the orientation of the wrist and hand appropriately for the object. Here we used functional magnetic resonance imaging adaptation (fMRA) to investigate human brain areas involved in processing hand orientation during grasping movements. Participants used the dominant right hand to grasp a rod with the four fingers opposing the thumb or to reach and touch the rod with the knuckles without visual feedback. In a control condition, participants passively viewed the rod. Trials in a slow event-related design consisted of two sequential stimuli in which the rod orientation changed (requiring a change in wrist posture while grasping but not reaching or looking) or remained the same. We found reduced activation, that is, adaptation, in superior parieto-occipital cortex (SPOC) when the object was repeatedly grasped with the same orientation. In contrast, there was no adaptation when reaching or looking at an object in the same orientation, suggesting that hand orientation, rather than object orientation, was the critical factor. These results agree with recent neurophysiological research showing that a parieto-occipital area of macaque (V6A) is modulated by hand orientation during reach-to-grasp movements. We suggest that the human dorsomedial stream, like that in the macaque, plays a key role in processing hand orientation in reach-to-grasp movements.

  15. Flicker Adaptation of Low-Level Cortical Visual Neurons Contributes to Temporal Dilation

    ERIC Educational Resources Information Center

    Ortega, Laura; Guzman-Martinez, Emmanuel; Grabowecky, Marcia; Suzuki, Satoru

    2012-01-01

    Several seconds of adaptation to a flickered stimulus causes a subsequent brief static stimulus to appear longer in duration. Nonsensory factors, such as increased arousal and attention, have been thought to mediate this flicker-based temporal-dilation aftereffect. In this study, we provide evidence that adaptation of low-level cortical visual…

  16. Manipulation of visual biofeedback during gait with a time delayed adaptive Virtual Mirror Box

    PubMed Central

    2014-01-01

    Background A mirror placed in the mid-sagittal plane of the body has been used to reduce phantom limb pain and improve movement function in medical conditions characterised by asymmetrical movement control. The mirrored illusion of unimpaired limb movement during gait might enhance the effect, but a physical mirror is only capable of showing parallel movement of limbs in real time typically while sitting. We aimed to overcome the limitations of physical mirrors by developing and evaluating a Virtual Mirror Box which delays the mirrored image of limbs during gait to ensure temporal congruency with the impaired physical limb. Methods An application was developed in the CAREN system’s D-Flow software which mirrors selected limbs recorded by real-time motion capture to the contralateral side. To achieve phase shifted movement of limbs during gait, the mirrored virtual limbs are also delayed by a continuously calculated amount derived from past gait events. In order to accommodate non-normal proportions and offsets of pathological gait, the movements are morphed so that the physical and virtual contact events match on the mirrored side. Our method was tested with a trans-femoral amputee walking on a treadmill using his artificial limb. Joint angles of the elbow and knee were compared between the intact and mirrored side using cross correlation, root mean squared difference and correlation coefficients. Results The time delayed adaptive virtual mirror box produced a symmetrical looking gait of the avatar coupled with a reduction of the difference between the intact and virtual knee and elbow angles (10.86° and 5.34° reduced to 4.99° and 2.54° respectively). Dynamic morphing of the delay caused a non-significant change of toe-off events when compared to delaying by 50% of the previous gait cycle, as opposed to the initial contact events which showed a practically negligible but statistically significant increase (p < 0.05). Conclusions Adding an adaptive time

  17. Query-Driven Visualization of Time-Varying Adaptive Mesh Refinement Data

    SciTech Connect

    Gosink, Luke J.; Anderson, John C.; Bethel, E. Wes; Joy, Kenneth I.

    2008-08-01

    The visualization and analysis of AMR-based simulations is integral to the process of obtaining new insight in scientific research. We present a new method for performing query-driven visualization and analysis on AMR data, with specific emphasis on time-varying AMR data. Our work introduces a new method that directly addresses the dynamic spatial and temporal properties of AMR grids which challenge many existing visualization techniques. Further, we present the first implementation of query-driven visualization on the GPU that uses a GPU-based indexing structure to both answer queries and efficiently utilize GPU memory. We apply our method to two different science domains to demonstrate its broad applicability.

  18. Adaptive Blood Glucose Monitoring and Insulin Measurement Devices for Visually Impaired Persons.

    ERIC Educational Resources Information Center

    Petzinger, R. A.

    1993-01-01

    This article describes devices that people with visual impairments and diabetes can use to monitor blood glucose levels and measure insulin. A table lists devices, their manufacturers (including address and telephone number), and comments about the devices. (DB)

  19. Influence of adaptive-optics ocular aberration correction on visual acuity at different luminances and contrast polarities.

    PubMed

    Marcos, Susana; Sawides, Lucie; Gambra, Enrique; Dorronsoro, Carlos

    2008-10-06

    We evaluated the visual benefit of correcting astigmatism and high-order aberrations with adaptive optics (AO) on visual acuity (VA) measured at 7 different luminances (ranging from 0.8 to 50 cd/m(2)) and two contrast polarities (black letters on white background, BoW, and white letters on black background, WoB) on 7 subjects. For the BoW condition, VA increased with background luminance in both natural and AO-corrected conditions, and there was a benefit of AO correction at all luminances (by a factor of 1.29 on average across luminances). For WoB VA increased with foreground luminance but decreased for the highest luminances. In this reversed polarity condition AO correction increased VA by a factor of 1.13 on average and did not produce a visual benefit at high luminances. The improvement of VA (averaged across conditions) was significantly correlated (p = 0.04) with the amount of corrected aberrations (in terms of Strehl ratio). The improved performance with WoB targets with respect to BoW targets is decreased when correcting aberrations, suggesting a role of ocular aberrations in the differences in visual performance between contrast polarities.

  20. Visual ecology of Indian carpenter bees II: adaptations of eyes and ocelli to nocturnal and diurnal lifestyles.

    PubMed

    Somanathan, Hema; Kelber, Almut; Borges, Renee M; Wallén, Rita; Warrant, Eric J

    2009-06-01

    Most bees are diurnal, with behaviour that is largely visually mediated, but several groups have made evolutionary shifts to nocturnality, despite having apposition compound eyes unsuited to vision in dim light. We compared the anatomy and optics of the apposition eyes and the ocelli of the nocturnal carpenter bee, Xylocopa tranquebarica, with two sympatric species, the strictly diurnal X. leucothorax and the occasionally crepuscular X. tenuiscapa. The ocelli of the nocturnal X. tranquebarica are unusually large (diameter ca. 1 mm) and poorly focussed. Moreover, their apposition eyes show specific visual adaptations for vision in dim light, including large size, large facets and very wide rhabdoms, which together make these eyes 9 times more sensitive than those of X. tenuiscapa and 27 times more sensitive than those of X. leucothorax. These differences in optical sensitivity are surprisingly small considering that X. tranquebarica can fly on moonless nights when background luminance is as low as 10(-5) cd m(-2), implying that this bee must employ additional visual strategies to forage and find its way back to the nest. These strategies may include photoreceptors with longer integration times and higher contrast gains as well as higher neural summation mechanisms for increasing visual reliability in dim light.

  1. Semiautomatic transfer function initialization for abdominal visualization using self-generating hierarchical radial basis function networks.

    PubMed

    Selver, M Alper; Güzeliş, Cüneyt

    2009-01-01

    As being a tool that assigns optical parameters used in interactive visualization, Transfer Functions (TF) have important effects on the quality of volume rendered medical images. Unfortunately, finding accurate TFs is a tedious and time consuming task because of the trade off between using extensive search spaces and fulfilling the physician's expectations with interactive data exploration tools and interfaces. By addressing this problem, we introduce a semi-automatic method for initial generation of TFs. The proposed method uses a Self Generating Hierarchical Radial Basis Function Network to determine the lobes of a Volume Histogram Stack (VHS) which is introduced as a new domain by aligning the histograms of slices of a image series. The new self generating hierarchical design strategy allows the recognition of suppressed lobes corresponding to suppressed tissues and representation of the overlapping regions which are parts of the lobes but can not be represented by the Gaussian bases in VHS. Moreover, approximation with a minimum set of basis functions provides the possibility of selecting and adjusting suitable units to optimize the TF. Applications on different CT and MR data sets show enhanced rendering quality and reduced optimization time in abdominal studies.

  2. IMAGING WITH MULTIMODAL ADAPTIVE-OPTICS OPTICAL COHERENCE TOMOGRAPHY IN MULTIPLE EVANESCENT WHITE DOT SYNDROME: THE STRUCTURE AND FUNCTIONAL RELATIONSHIP

    PubMed Central

    Legarreta, Andrew D.; Legarreta, John E.; Nadler, Zach; Gallagher, Denise; Hammer, Daniel X.; Ferguson, R. Daniel; Iftimia, Nicusor; Wollstein, Gadi; Schuman, Joel S.

    2016-01-01

    Purpose: To elucidate the location of pathological changes in multiple evanescent white dot syndrome (MEWDS) with the use of multimodal adaptive optics (AO) imaging. Methods: A 5-year observational case study of a 24-year-old female with recurrent MEWDS. Full examination included history, Snellen chart visual acuity, pupil assessment, intraocular pressures, slit lamp evaluation, dilated fundoscopic exam, imaging with Fourier-domain optical coherence tomography (FD-OCT), blue-light fundus autofluorescence (FAF), fundus photography, fluorescein angiography, and adaptive-optics optical coherence tomography. Results: Three distinct acute episodes of MEWDS occurred during the period of follow-up. Fourier-domain optical coherence tomography and adaptive-optics imaging showed disturbance in the photoreceptor outer segments (PR OS) in the posterior pole with each flare. The degree of disturbance at the photoreceptor level corresponded to size and extent of the visual field changes. All findings were transient with delineation of the photoreceptor recovery from the outer edges of the lesion inward. Hyperautofluorescence was seen during acute flares. Increase in choroidal thickness did occur with each active flare but resolved. Conclusion: Although changes in the choroid and RPE can be observed in MEWDS, Fourier-domain optical coherence tomography, and multimodal adaptive optics imaging localized the visually significant changes seen in this disease at the level of the photoreceptors. These transient retinal changes specifically occur at the level of the inner segment ellipsoid and OS/RPE line. En face optical coherence tomography imaging provides a detailed, yet noninvasive method for following the convalescence of MEWDS and provides insight into the structural and functional relationship of this transient inflammatory retinal disease. PMID:26735319

  3. Visualization of Potential Energy Function Using an Isoenergy Approach and 3D Prototyping

    ERIC Educational Resources Information Center

    Teplukhin, Alexander; Babikov, Dmitri

    2015-01-01

    In our three-dimensional world, one can plot, see, and comprehend a function of two variables at most, V(x,y). One cannot plot a function of three or more variables. For this reason, visualization of the potential energy function in its full dimensionality is impossible even for the smallest polyatomic molecules, such as triatomics. This creates…

  4. Reducing uncertainty about objective functions in adaptive management

    USGS Publications Warehouse

    Williams, B.K.

    2012-01-01

    This paper extends the uncertainty framework of adaptive management to include uncertainty about the objectives to be used in guiding decisions. Adaptive decision making typically assumes explicit and agreed-upon objectives for management, but allows for uncertainty as to the structure of the decision process that generates change through time. Yet it is not unusual for there to be uncertainty (or disagreement) about objectives, with different stakeholders expressing different views not only about resource responses to management but also about the appropriate management objectives. In this paper I extend the treatment of uncertainty in adaptive management, and describe a stochastic structure for the joint occurrence of uncertainty about objectives as well as models, and show how adaptive decision making and the assessment of post-decision monitoring data can be used to reduce uncertainties of both kinds. Different degrees of association between model and objective uncertainty lead to different patterns of learning about objectives. ?? 2011.

  5. Visual function and color vision in adults with Attention-Deficit/Hyperactivity Disorder

    PubMed Central

    Kim, Soyeon; Chen, Samantha; Tannock, Rosemary

    2013-01-01

    Purpose Color vision and self-reported visual function in everyday life in young adults with Attention-Deficit/Hyperactivity Disorder (ADHD) were investigated. Method Participants were 30 young adults with ADHD and 30 controls matched for age and gender. They were tested individually and completed the Visual Activities Questionnaire (VAQ), Farnsworth-Munsell 100 Hue Test (FMT) and A Quick Test of Cognitive Speed (AQT). Results The ADHD group reported significantly more problems in 4 of 8 areas on the VAQ: depth perception, peripheral vision, visual search and visual processing speed. Further analyses of VAQ items revealed that the ADHD group endorsed more visual problems associated with driving than controls. Color perception difficulties on the FMT were restricted to the blue spectrum in the ADHD group. FMT and AQT results revealed slower processing of visual stimuli in the ADHD group. Conclusion A comprehensive investigation of mechanisms underlying visual function and color vision in adults with ADHD is warranted, along with the potential impact of these visual problems on driving performance. PMID:24646898

  6. [An Evaluation of Visual Function in Working Age Patients with Glaucoma].

    PubMed

    Murakami, Miki; Obata, Yasuko; Yamato, Hiroshi; Kondo, Hiroyuki

    2015-09-01

    Visual function affects working ability in occupational health. We investigated the frequencies and grades of low vision in working age people who have glaucoma, and studied patients who were receiving low vision care, for example eye movement training. Among 3,905 patients aged 15 to 64 years old who visited Murakami eye clinic from October 2013 to September 2014, there were 363 patients suspected of having glaucoma and 138 patients diagnosed with glaucoma and receiving treatment. We measured their visual acuity and visual field to calculate their functional vision score (FVS). We studied the amount of reduction in visual ability and the number of patients undergoing low vision care by age groups. The vision test and visual field test showed that 18 patients had reduced visual ability, according to the FVS. Their FVS classification was from class 1 (mild vision loss) to class 3a (severe vision loss). The FVS matches the statistics of the WHO and can predict the reading and walking ability in each class. Reduced visual ability was recognized in about 14% of the glaucoma patients older than 45 years of age. 78% of the patients were classified in class 1. In FVS, class 2 (moderate vision loss) or greater is defined as low vision, and class 1 is a condition with no visual reserve. Although such patients have no problems in daily life and office work, they are challenged by on-site work and the on-site environment, and occupational health staff intervention becomes necessary.

  7. Tracking the evolution of crossmodal plasticity and visual functions before and after sight restoration

    PubMed Central

    Dormal, Giulia; Lepore, Franco; Harissi-Dagher, Mona; Albouy, Geneviève; Bertone, Armando; Rossion, Bruno

    2014-01-01

    Visual deprivation leads to massive reorganization in both the structure and function of the occipital cortex, raising crucial challenges for sight restoration. We tracked the behavioral, structural, and neurofunctional changes occurring in an early and severely visually impaired patient before and 1.5 and 7 mo after sight restoration with magnetic resonance imaging. Robust presurgical auditory responses were found in occipital cortex despite residual preoperative vision. In primary visual cortex, crossmodal auditory responses overlapped with visual responses and remained elevated even 7 mo after surgery. However, these crossmodal responses decreased in extrastriate occipital regions after surgery, together with improved behavioral vision and with increases in both gray matter density and neural activation in low-level visual regions. Selective responses in high-level visual regions involved in motion and face processing were observable even before surgery and did not evolve after surgery. Taken together, these findings demonstrate that structural and functional reorganization of occipital regions are present in an individual with a long-standing history of severe visual impairment and that such reorganizations can be partially reversed by visual restoration in adulthood. PMID:25520432

  8. Mechanisms of recovery of visual function in adult amblyopia through a tailored action video game

    PubMed Central

    Vedamurthy, Indu; Nahum, Mor; Bavelier, Daphne; Levi, Dennis M.

    2015-01-01

    Amblyopia is a deficit in vision that arises from abnormal visual experience early in life. It was long thought to develop into a permanent deficit, unless properly treated before the end of the sensitive period for visual recovery. However, a number of studies now suggest that adults with long-standing amblyopia may at least partially recover visual acuity and stereopsis following perceptual training. Eliminating or reducing interocular suppression has been hypothesized to be at the root of these changes. Here we show that playing a novel dichoptic video game indeed results in reduced suppression, improved visual acuity and, in some cases, improved stereopsis. Our relatively large cohort of adults with amblyopia, allowed us, for the first time, to assess the link between visual function recovery and reduction in suppression. Surprisingly, no significant correlation was found between decreased suppression and improved visual function. This finding challenges the prevailing view and suggests that while dichoptic training improves visual acuity and stereopsis in adult amblyopia, reduced suppression is unlikely to be at the root of visual recovery. These results are discussed in the context of their implication on recovery of amblyopia in adults. PMID:25719537

  9. Visualizing the functional architecture of the endocytic machinery.

    PubMed

    Picco, Andrea; Mund, Markus; Ries, Jonas; Nédélec, François; Kaksonen, Marko

    2015-02-12

    Clathrin-mediated endocytosis is an essential process that forms vesicles from the plasma membrane. Although most of the protein components of the endocytic protein machinery have been thoroughly characterized, their organization at the endocytic site is poorly understood. We developed a fluorescence microscopy method to track the average positions of yeast endocytic proteins in relation to each other with a time precision below 1 s and with a spatial precision of ~10 nm. With these data, integrated with shapes of endocytic membrane intermediates and with superresolution imaging, we could visualize the dynamic architecture of the endocytic machinery. We showed how different coat proteins are distributed within the coat structure and how the assembly dynamics of N-BAR proteins relate to membrane shape changes. Moreover, we found that the region of actin polymerization is located at the base of the endocytic invagination, with the growing ends of filaments pointing toward the plasma membrane.

  10. Waking and Dreaming Need Profiles: An Exploratory Study of Adaptive Functioning.

    ERIC Educational Resources Information Center

    Hutchinson, Robert Linton, II

    Research has defined the various adaptive, compensatory and complementary functions of dreams. To investigate the evidence of adaptive functioning in the dream state, 30 medical students (21 males, 9 females) from St. George's University, Grenada, completed personal surveys, a waking psychological profile, and a dreaming psychological profile…

  11. Associations between Conceptual Reasoning, Problem Solving, and Adaptive Ability in High-Functioning Autism

    ERIC Educational Resources Information Center

    Williams, Diane L.; Mazefsky, Carla A.; Walker, Jon D.; Minshew, Nancy J.; Goldstein, Gerald

    2014-01-01

    Abstract thinking is generally highly correlated with problem-solving ability which is predictive of better adaptive functioning. Measures of conceptual reasoning, an ecologically-valid laboratory measure of problem-solving, and a report measure of adaptive functioning in the natural environment, were administered to children and adults with and…

  12. Through evolution's eyes: extracting mate preferences by linking visual attention to adaptive design.

    PubMed

    Krupp, Daniel Brian

    2008-02-01

    Information is crucial to decision-making, including mate choice decisions. Perceptual systems, such as attention, evolved in part to forage for reproductive information; consequently, these systems can be used to reveal mate preferences. Here, I consider the place of visual information in human mate choice and provide a rationale for pressing into service methods drawn from the attention literature for the study of mate choice decisions. Because visual attention is allocated automatically and selectively, it may be used to complement common methods of mate preference assessment, such as self-report questionnaires and measures of genital arousal, while avoiding some of the pitfalls of these methods. Beyond the utility of increasing confidence in extant research findings by employing relatively unobtrusive methods, visual attention paradigms can also allow researchers to explore a variety of questions that are rarely asked, such as those concerned with signal efficiency and tradeoffs in the assessment of mate value.

  13. Tactile perception recruits functionally related visual areas in the late-blind.

    PubMed

    Goyal, Manu S; Hansen, Peter J; Blakemore, Colin B

    2006-09-18

    When blind people touch Braille characters, blood flow increases in visual areas, leading to speculation that visual circuitry assists tactile discrimination in the blind. We tested this hypothesis in a functional magnetic resonance imaging study designed to reveal activation appropriate to the nature of tactile stimulation. In late-blind individuals, hMT/V5 and fusiform face area activated during visual imagery of moving patterns or faces. When they touched a doll's face, right fusiform face area was again activated. Equally, hMT/V5 was activated when objects moved over the skin. We saw no difference in hMT/V5 or fusiform face area activity during motion or face perception in the congenitally blind. We conclude that specialized visual areas, once established through visual experience, assist equivalent tactile identification tasks years after the onset of blindness.

  14. Brief Report: Adaptive Functioning in Children with ASD, ADHD and ASD + ADHD.

    PubMed

    Ashwood, Karen L; Tye, Charlotte; Azadi, Bahare; Cartwright, Sally; Asherson, Philip; Bolton, Patrick

    2015-07-01

    Autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) often co-occur. Children with ASD and ADHD demonstrate deficits in adaptive functioning, yet pure and comorbid groups have not been directly compared. Vineland Adaptive Behaviour Scales (VABS-II) data were examined in boys with ASD (n = 17), ADHD (n = 31) and ASD + ADHD (n = 38). Results demonstrated lower socialisation and composite scores and greater discrepancy between cognitive and adaptive abilities in the ASD + ADHD group compared to the ADHD-only group. Significant associations were shown between reduced adaptive functioning and autism symptoms, but not ADHD symptoms. Children with ASD + ADHD present with exacerbated impairments in adaptive functioning relative to children with ADHD, associated with ASD symptoms. Disentangling variation in adaptive skills may aid the assessment of complex cases.

  15. The early visual encoding of a face (N170) is viewpoint-dependent: a parametric ERP-adaptation study.

    PubMed

    Caharel, Stéphanie; Collet, Kevin; Rossion, Bruno

    2015-03-01

    Visual representations of faces are extracted shortly after 100 ms in the human brain, leading to an occipito-temporal cortex N170 event-related potential (ERP). To understand the nature of this early visual representation, a full-front adapting face preceded a different or identical target face identity. The target face varied parametrically in head orientation from the adapting face (0-90°, 15° steps). The N170 elicited by the target face increased progressively from 0° up to 30° head orientation, with no further increase until 90°. The N170 decreased for repeated face identities, this effect being stable between 0° and 30° changes of viewpoint, and no effect beyond that angle. These observations suggest that a face is encoded in a view-dependent manner, being matched to either a full-front or a profile face view. Yet, individual face representations activated as early as the peak of the N170 generalize partially across views.

  16. Visualizing the functional architecture of the endocytic machinery

    PubMed Central

    Picco, Andrea; Mund, Markus; Ries, Jonas; Nédélec, François; Kaksonen, Marko

    2015-01-01

    Clathrin-mediated endocytosis is an essential process that forms vesicles from the plasma membrane. Although most of the protein components of the endocytic protein machinery have been thoroughly characterized, their organization at the endocytic site is poorly understood. We developed a fluorescence microscopy method to track the average positions of yeast endocytic proteins in relation to each other with a time precision below 1 s and with a spatial precision of ∼10 nm. With these data, integrated with shapes of endocytic membrane intermediates and with superresolution imaging, we could visualize the dynamic architecture of the endocytic machinery. We showed how different coat proteins are distributed within the coat structure and how the assembly dynamics of N-BAR proteins relate to membrane shape changes. Moreover, we found that the region of actin polymerization is located at the base of the endocytic invagination, with the growing ends of filaments pointing toward the plasma membrane. DOI: http://dx.doi.org/10.7554/eLife.04535.001 PMID:25675087

  17. Inhibition of the Pim1 Oncogene Results in Diminished Visual Function

    PubMed Central

    Yin, Jun; Shine, Lisa; Raycroft, Francis; Deeti, Sudhakar; Reynolds, Alison; Ackerman, Kristin M.; Glaviano, Antonino; O'Farrell, Sean; O'Leary, Olivia; Kilty, Claire; Kennedy, Ciaran; McLoughlin, Sarah; Rice, Megan; Russell, Eileen; Higgins, Desmond G.; Hyde, David R.; Kennedy, Breandan N.

    2012-01-01

    Our objective was to profile genetic pathways whose differential expression correlates with maturation of visual function in zebrafish. Bioinformatic analysis of transcriptomic data revealed Jak-Stat signalling as the pathway most enriched in the eye, as visual function develops. Real-time PCR, western blotting, immunohistochemistry and in situ hybridization data confirm that multiple Jak-Stat pathway genes are up-regulated in the zebrafish eye between 3–5 days post-fertilisation, times associated with significant maturation of vision. One of the most up-regulated Jak-Stat genes is the proto-oncogene Pim1 kinase, previously associated with haematological malignancies and cancer. Loss of function experiments using Pim1 morpholinos or Pim1 inhibitors result in significant diminishment of visual behaviour and function. In summary, we have identified that enhanced expression of Jak-Stat pathway genes correlates with maturation of visual function and that the Pim1 oncogene is required for normal visual function. PMID:23300608

  18. Changes in Connectivity after Visual Cortical Brain Damage Underlie Altered Visual Function

    ERIC Educational Resources Information Center

    Bridge, Holly; Thomas, Owen; Jbabdi, Saad; Cowey, Alan

    2008-01-01

    The full extent of the brain's ability to compensate for damage or changed experience is yet to be established. One question particularly important for evaluating and understanding rehabilitation following brain damage is whether recovery involves new and aberrant neural connections or whether any change in function is due to the functional…

  19. Permanent functional reorganization of retinal circuits induced by early long-term visual deprivation.

    PubMed

    Di Marco, Stefano; Nguyen, Vincent A; Bisti, Silvia; Protti, Dario A

    2009-10-28

    Early sensory experience shapes the functional and anatomical connectivity of neuronal networks. Light deprivation alters synaptic transmission and modifies light response properties in the visual system, from retinal circuits to higher visual centers. These effects are more pronounced during a critical period in juvenile life and are mostly reversed by restoring normal light conditions. Here we show that complete light deprivation, from birth to periods beyond the critical period, permanently modifies the receptive field properties of retinal ganglion cells. Visual deprivation reduced both the strength of light responses in ganglion cells and their receptive field size. Light deprivation produced an imbalance in the ratio of inhibitory to excitatory inputs, with a shift toward larger inhibitory conductances. Ganglion cell receptive fields in visually deprived animals showed a spatial mismatch of inhibitory and excitatory inputs and inhibitory inputs were highly scattered over the receptive field. These results indicate that visual experience early in life is critical for the refinement of retinal circuits and for appropriate signaling of the spatiotemporal properties of visual stimuli, thus influencing the response properties of neurons in higher visual centers and their processing of visual information.

  20. The disorganized visual cortex in reelin-deficient mice is functional and allows for enhanced plasticity.

    PubMed

    Pielecka-Fortuna, Justyna; Wagener, Robin Jan; Martens, Ann-Kristin; Goetze, Bianka; Schmidt, Karl-Friedrich; Staiger, Jochen F; Löwel, Siegrid

    2015-11-01

    A hallmark of neocortical circuits is the segregation of processing streams into six distinct layers. The importance of this layered organization for cortical processing and plasticity is little understood. We investigated the structure, function and plasticity of primary visual cortex (V1) of adult mice deficient for the glycoprotein reelin and their wild-type littermates. In V1 of rl-/- mice, cells with different laminar fates are present at all cortical depths. Surprisingly, the (vertically) disorganized cortex maintains a precise retinotopic (horizontal) organization. Rl-/- mice have normal basic visual capabilities, but are compromised in more challenging perceptual tasks, such as orientation discrimination. Additionally, rl-/- animals learn and memorize a visual task as well as their wild-type littermates. Interestingly, reelin deficiency enhances visual cortical plasticity: juvenile-like ocular dominance plasticity is preserved into late adulthood. The present data offer an important insight into the capabilities of a disorganized cortical system to maintain basic functional properties.

  1. The Impact of Visual Guided Order Picking on Ocular Comfort, Ocular Surface and Tear Function

    PubMed Central

    Klein-Theyer, Angelika; Horwath-Winter, Jutta; Rabensteiner, Dieter Franz; Schwantzer, Gerold; Wultsch, Georg; Aminfar, Haleh; Heidinger, Andrea; Boldin, Ingrid

    2016-01-01

    Purpose We investigated the effects of a visual picking system on ocular comfort, the ocular surface and tear function compared to those of a voice guided picking solution. Design Prospective, observational, cohort study. Method Setting: Institutional. Study Population: A total of 25 young asymptomatic volunteers performed commissioning over 10 hours on two consecutive days. Main Outcome Measures: The operators were guided in the picking process by two different picking solutions, either visually or by voice while their subjective symptoms and ocular surface and tear function parameters were recorded. Results The visual analogue scale (VAS) values, according to subjective dry eye symptoms, in the visual condition were significantly higher at the end of the commissioning than the baseline measurements. In the voice condition, the VAS values remained stable during the commissioning. The tear break-up time (BUT) values declined significantly in the visual condition (pre-task: 16.6 sec and post-task: 9.6 sec) in the right eyes, that were exposed to the displays, the left eyes in the visual condition showed only a minor decline, whereas the BUT values in the voice condition remained constant (right eyes) or even increased (left eyes) over the time. No significant differences in the tear meniscus height values before and after the commissioning were observed in either condition. Conclusion In our study, the use of visually guided picking solutions was correlated with post-task subjective symptoms and tear film instability. PMID:27314855

  2. Adaptation.

    PubMed

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

  3. Choosing Your Poison: Optimizing Simulator Visual System Selection as a Function of Operational Tasks

    NASA Technical Reports Server (NTRS)

    Sweet, Barbara T.; Kaiser, Mary K.

    2013-01-01

    Although current technology simulator visual systems can achieve extremely realistic levels they do not completely replicate the experience of a pilot sitting in the cockpit, looking at the outside world. Some differences in experience are due to visual artifacts, or perceptual features that would not be present in a naturally viewed scene. Others are due to features that are missing from the simulated scene. In this paper, these differences will be defined and discussed. The significance of these differences will be examined as a function of several particular operational tasks. A framework to facilitate the choice of visual system characteristics based on operational task requirements will be proposed.

  4. Optical properties of retinal tissue and the potential of adaptive optics to visualize retinal ganglion cells in vivo.

    PubMed

    Prasse, Martina; Rauscher, Franziska Georgia; Wiedemann, Peter; Reichenbach, Andreas; Francke, Mike

    2013-08-01

    Many efforts have been made to improve the diagnostic tools used to identify and to estimate the progress of ganglion cell and nerve fibre degeneration in glaucoma. Imaging by optical coherence tomography and measurements of the dimensions of the optic nerve head and the nerve fibre layer in central retinal areas is currently used to estimate the grade of pathological changes. The visualization and quantification of ganglion cells and nerve fibres directly in patients would dramatically improve glaucoma diagnostics. We have investigated the optical properties of cellular structures of retinal tissue in order to establish a means of visualizing and quantifying ganglion cells in the living retina without staining. We have characterized the optical properties of retinal tissue in several species including humans. Nerve fibres, blood vessels, ganglion cells and their cell processes have been visualized at high image resolution by means of the reflection mode of a confocal laser scanning microscope. The potential of adaptive optics in current imaging systems and the possibilities of imaging single ganglion cells non-invasively in patients are discussed.

  5. Scalable Adaptive Graphics Environment (SAGE) Software for the Visualization of Large Data Sets on a Video Wall

    NASA Technical Reports Server (NTRS)

    Jedlovec, Gary; Srikishen, Jayanthi; Edwards, Rita; Cross, David; Welch, Jon; Smith, Matt

    2013-01-01

    The use of collaborative scientific visualization systems for the analysis, visualization, and sharing of "big data" available from new high resolution remote sensing satellite sensors or four-dimensional numerical model simulations is propelling the wider adoption of ultra-resolution tiled display walls interconnected by high speed networks. These systems require a globally connected and well-integrated operating environment that provides persistent visualization and collaboration services. This abstract and subsequent presentation describes a new collaborative visualization system installed for NASA's Shortterm Prediction Research and Transition (SPoRT) program at Marshall Space Flight Center and its use for Earth science applications. The system consists of a 3 x 4 array of 1920 x 1080 pixel thin bezel video monitors mounted on a wall in a scientific collaboration lab. The monitors are physically and virtually integrated into a 14' x 7' for video display. The display of scientific data on the video wall is controlled by a single Alienware Aurora PC with a 2nd Generation Intel Core 4.1 GHz processor, 32 GB memory, and an AMD Fire Pro W600 video card with 6 mini display port connections. Six mini display-to-dual DVI cables are used to connect the 12 individual video monitors. The open source Scalable Adaptive Graphics Environment (SAGE) windowing and media control framework, running on top of the Ubuntu 12 Linux operating system, allows several users to simultaneously control the display and storage of high resolution still and moving graphics in a variety of formats, on tiled display walls of any size. The Ubuntu operating system supports the open source Scalable Adaptive Graphics Environment (SAGE) software which provides a common environment, or framework, enabling its users to access, display and share a variety of data-intensive information. This information can be digital-cinema animations, high-resolution images, high-definition video

  6. Scalable Adaptive Graphics Environment (SAGE) Software for the Visualization of Large Data Sets on a Video Wall

    NASA Astrophysics Data System (ADS)

    Jedlovec, G.; Srikishen, J.; Edwards, R.; Cross, D.; Welch, J. D.; Smith, M. R.

    2013-12-01

    The use of collaborative scientific visualization systems for the analysis, visualization, and sharing of 'big data' available from new high resolution remote sensing satellite sensors or four-dimensional numerical model simulations is propelling the wider adoption of ultra-resolution tiled display walls interconnected by high speed networks. These systems require a globally connected and well-integrated operating environment that provides persistent visualization and collaboration services. This abstract and subsequent presentation describes a new collaborative visualization system installed for NASA's Short-term Prediction Research and Transition (SPoRT) program at Marshall Space Flight Center and its use for Earth science applications. The system consists of a 3 x 4 array of 1920 x 1080 pixel thin bezel video monitors mounted on a wall in a scientific collaboration lab. The monitors are physically and virtually integrated into a 14' x 7' for video display. The display of scientific data on the video wall is controlled by a single Alienware Aurora PC with a 2nd Generation Intel Core 4.1 GHz processor, 32 GB memory, and an AMD Fire Pro W600 video card with 6 mini display port connections. Six mini display-to-dual DVI cables are used to connect the 12 individual video monitors. The open source Scalable Adaptive Graphics Environment (SAGE) windowing and media control framework, running on top of the Ubuntu 12 Linux operating system, allows several users to simultaneously control the display and storage of high resolution still and moving graphics in a variety of formats, on tiled display walls of any size. The Ubuntu operating system supports the open source Scalable Adaptive Graphics Environment (SAGE) software which provides a common environment, or framework, enabling its users to access, display and share a variety of data-intensive information. This information can be digital-cinema animations, high-resolution images, high-definition video

  7. Functional genomics of physiological plasticity and local adaptation in killifish.

    PubMed

    Whitehead, Andrew; Galvez, Fernando; Zhang, Shujun; Williams, Larissa M; Oleksiak, Marjorie F

    2011-01-01

    Evolutionary solutions to the physiological challenges of life in highly variable habitats can span the continuum from evolution of a cosmopolitan plastic phenotype to the evolution of locally adapted phenotypes. Killifish (Fundulus sp.) have evolved both highly plastic and locally adapted phenotypes within different selective contexts, providing a comparative system in which to explore the genomic underpinnings of physiological plasticity and adaptive variation. Importantly, extensive variation exists among populations and species for tolerance to a variety of stressors, and we exploit this variation in comparative studies to yield insights into the genomic basis of evolved phenotypic variation. Notably, species of Fundulus occupy the continuum of osmotic habitats from freshwater to marine and populations within Fundulus heteroclitus span far greater variation in pollution tolerance than across all species of fish. Here, we explore how transcriptome regulation underpins extreme physiological plasticity on osmotic shock and how genomic and transcriptomic variation is associated with locally evolved pollution tolerance. We show that F. heteroclitus quickly acclimate to extreme osmotic shock by mounting a dramatic rapid transcriptomic response including an early crisis control phase followed by a tissue remodeling phase involving many regulatory pathways. We also show that convergent evolution of locally adapted pollution tolerance involves complex patterns of gene expression and genome sequence variation, which is confounded with body-weight dependence for some genes. Similarly, exploiting the natural phenotypic variation associated with other established and emerging model organisms is likely to greatly accelerate the pace of discovery of the genomic basis of phenotypic variation.

  8. Visualizing the Chain Rule (for Functions over R and C) and More

    ERIC Educational Resources Information Center

    Kreminski, Rick

    2009-01-01

    A visual approach to understanding the chain rule and related derivative formulae, for functions from R to R and from C to C, is presented. This apparently novel approach has been successfully used with several audiences: students first studying calculus, students with some background in linear algebra, students beginning study of functions of a…

  9. FuncTree: Functional Analysis and Visualization for Large-Scale Omics Data.

    PubMed

    Uchiyama, Takeru; Irie, Mitsuru; Mori, Hiroshi; Kurokawa, Ken; Yamada, Takuji

    2015-01-01

    Exponential growth of high-throughput data and the increasing complexity of omics information have been making processing and interpreting biological data an extremely difficult and daunting task. Here we developed FuncTree (http://bioviz.tokyo/functree), a web-based application for analyzing and visualizing large-scale omics data, including but not limited to genomic, metagenomic, and transcriptomic data. FuncTree allows user to map their omics data onto the "Functional Tree map", a predefined circular dendrogram, which represents the hierarchical relationship of all known biological functions defined in the KEGG database. This novel visualization method allows user to overview the broad functionality of their data, thus allowing a more accurate and comprehensive understanding of the omics information. FuncTree provides extensive customization and calculation methods to not only allow user to directly map their omics data to identify the functionality of their data, but also to compute statistically enriched functions by comparing it to other predefined omics data. We have validated FuncTree's analysis and visualization capability by mapping pan-genomic data of three different types of bacterial genera, metagenomic data of the human gut, and transcriptomic data of two different types of human cell expression. All three mapping strongly confirms FuncTree's capability to analyze and visually represent key functional feature of the omics data. We believe that FuncTree's capability to conduct various functional calculations and visualizing the result into a holistic overview of biological function, would make it an integral analysis/visualization tool for extensive omics base research.

  10. Plasticity of Visual Pathways and Function in the Developing Brain: Is the Pulvinar a Crucial Player?

    PubMed Central

    Bourne, James A.; Morrone, Maria Concetta

    2017-01-01

    The pulvinar is the largest of the thalamic nuclei in the primates, including humans. In the primates, two of the three major subdivisions, the lateral and inferior pulvinar, are heavily interconnected with a significant proportion of the visual association cortex. However, while we now have a better understanding of the bidirectional connectivity of these pulvinar subdivisions, its functions remain somewhat of an enigma. Over the past few years, researchers have started to tackle this problem by addressing it from the angle of development and visual cortical lesions. In this review, we will draw together literature from the realms of studies in nonhuman primates and humans that have informed much of the current understanding. This literature has been responsible for changing many long-held opinions on the development of the visual cortex and how the pulvinar interacts dynamically with cortices during early life to ensure rapid development and functional capacity Furthermore, there is evidence to suggest involvement of the pulvinar following lesions of the primary visual cortex (V1) and geniculostriate pathway in early life which have far better functional outcomes than identical lesions obtained in adulthood. Shedding new light on the pulvinar and its role following lesions of the visual brain has implications for our understanding of visual brain disorders and the potential for recovery. PMID:28228719

  11. LGL: creating a map of protein function with an algorithm for visualizing very large biological networks.

    PubMed

    Adai, Alex T; Date, Shailesh V; Wieland, Shannon; Marcotte, Edward M

    2004-06-25

    Networks are proving to be central to the study of gene function, protein-protein interaction, and biochemical pathway data. Visualization of networks is important for their study, but visualization tools are often inadequate for working with very large biological networks. Here, we present an algorithm, called large graph layout (LGL), which can be used to dynamically visualize large networks on the order of hundreds of thousands of vertices and millions of edges. LGL applies a force-directed iterative layout guided by a minimal spanning tree of the network in order to generate coordinates for the vertices in two or three dimensions, which are subsequently visualized and interactively navigated with companion programs. We demonstrate the use of LGL in visualizing an extensive protein map summarizing the results of approximately 21 billion sequence comparisons between 145579 proteins from 50 genomes. Proteins are positioned in the map according to sequence homology and gene fusions, with the map ultimately serving as a theoretical framework that integrates inferences about gene function derived from sequence homology, remote homology, gene fusions, and higher-order fusions. We confirm that protein neighbors in the resulting map are functionally related, and that distinct map regions correspond to distinct cellular systems, enabling a computational strategy for discovering proteins' functions on the basis of the proteins' map positions. Using the map produced by LGL, we infer general functions for 23 uncharacterized protein families.

  12. Serial position effects in 2-alternative forced choice recognition: functional equivalence across visual and auditory modalities.

    PubMed

    Johnson, Andrew J; Miles, Christopher

    2009-01-01

    Two experiments examined Ward, Avons, and Melling's (2005) proposition that the serial position function is task, rather than modality, dependent. Specifically, they proposed that for backward testing the 2-alternative forced-choice (2AFC) recognition paradigm is characterised by single-item recency irrespective of the modality of the stimulus presentation. In Experiment 1 the same nonword sequences, presented both visually or auditorily, produced qualitatively equivalent serial position functions with 2AFC testing. Forward testing produced a flat serial position function, while backward testing produced two-item recency in the absence of primacy. In order to rule out the possibility that the serial position functions for visual stimuli were the product of sub-vocal rehearsal, Experiment 2 employed articulatory suppression during the presentation phase. Serial position function equivalence was again observed together with a modest impairment in overall recognition rates. Taken together, these data are consistent with the Ward et al. proposition and further support the existence of a visual memory that can facilitate storage of visual-verbal material (e.g. Logie, Della Sella, Wynn, & Baddeley, 2000). However, the observation of two-item recency contradicts the original duplex account of single-item recency traditionally observed for backwards recognition testing of visual stimuli (Phillips & Christie, 1977).

  13. Assessing dynamic spectral causality by lagged adaptive directed transfer function and instantaneous effect factor.

    PubMed

    Xu, Haojie; Lu, Yunfeng; Zhu, Shanan; He, Bin

    2014-07-01

    It is of significance to assess the dynamic spectral causality among physiological signals. Several practical estimators adapted from spectral Granger causality have been exploited to track dynamic causality based on the framework of time-varying multivariate autoregressive (tvMVAR) models. The nonzero covariance of the model's residuals has been used to describe the instantaneous effect phenomenon in some causality estimators. However, for the situations with Gaussian residuals in some autoregressive models, it is challenging to distinguish the directed instantaneous causality if the sufficient prior information about the "causal ordering" is missing. Here, we propose a new algorithm to assess the time-varying causal ordering of tvMVAR model under the assumption that the signals follow the same acyclic causal ordering for all time lags and to estimate the instantaneous effect factor (IEF) value in order to track the dynamic directed instantaneous connectivity. The time-lagged adaptive directed transfer function (ADTF) is also estimated to assess the lagged causality after removing the instantaneous effect. In this study, we first investigated the performance of the causal-ordering estimation algorithm and the accuracy of IEF value. Then, we presented the results of IEF and time-lagged ADTF method by comparing with the conventional ADTF method through simulations of various propagation models. Statistical analysis results suggest that the new algorithm could accurately estimate the causal ordering and give a good estimation of the IEF values in the Gaussian residual conditions. Meanwhile, the time-lagged ADTF approach is also more accurate in estimating the time-lagged dynamic interactions in a complex nervous system after extracting the instantaneous effect. In addition to the simulation studies, we applied the proposed method to estimate the dynamic spectral causality on real visual evoked potential (VEP) data in a human subject. Its usefulness in time

  14. Assessing Dynamic Spectral Causality by Lagged Adaptive Directed Transfer Function and Instantaneous Effect Factor

    PubMed Central

    Xu, Haojie; Lu, Yunfeng; Zhu, Shanan

    2014-01-01

    It is of significance to assess the dynamic spectral causality among physiological signals. Several practical estimators adapted from spectral Granger causality have been exploited to track dynamic causality based on the framework of time-varying multivariate autoregressive (tvMVAR) models. The non-zero covariance of the model’s residuals has been used to describe the instantaneous effect phenomenon in some causality estimators. However, for the situations with Gaussian residuals in some autoregressive models, it is challenging to distinguish the directed instantaneous causality if the sufficient prior information about the “causal ordering” is missing. Here, we propose a new algorithm to assess the time-varying causal ordering of tvMVAR model under the assumption that the signals follow the same acyclic causal ordering for all time lags and to estimate the instantaneous effect factor (IEF) value in order to track the dynamic directed instantaneous connectivity. The time-lagged adaptive directed transfer function (ADTF) is also estimated to assess the lagged causality after removing the instantaneous effect. In the present study, we firstly investigated the performance of the causal-ordering estimation algorithm and the accuracy of IEF value. Then, we presented the results of IEF and time-lagged ADTF method by comparing with the conventional ADTF method through simulations of various propagation models. Statistical analysis results suggest that the new algorithm could accurately estimate the causal ordering and give a good estimation of the IEF values in the Gaussian residual conditions. Meanwhile, the time-lagged ADTF approach is also more accurate in estimating the time-lagged dynamic interactions in a complex nervous system after extracting the instantaneous effect. In addition to the simulation studies, we applied the proposed method to estimate the dynamic spectral causality on real visual evoked potential (VEP) data in a human subject. Its usefulness in

  15. Visual and Proprioceptive Adaptation of Arm Position in a Virtual Environment.

    PubMed

    Masumoto, Junya; Inui, Nobuyuki

    2015-01-01

    The authors examined the resolution of a discrepancy between visual and proprioceptive estimates of arm position in 10 participants. The participants fixed their right shoulder at 0°, 30°, or 60° of transverse adduction while they viewed a video on a head-mounted display that showed their right arm extended in front of the trunk for 30 min. The perceived arm position more closely approached the seen arm position on the display as the difference between the actual and visually displayed arm positions increased. In the extreme case of a 90° discrepancy, the seen arm position on the display was very gradually perceived as approaching the actual arm position. The magnitude of changes in sensory estimates was larger for proprioception (20%) than for vision (< 10%).

  16. Visual-motor integration functioning in a South African middle childhood sample.

    PubMed

    Lotz, Leslie; Loxton, Helene; Naidoo, Anthony V

    2005-10-01

    Visual-motor integration functioning has been identified as playing an integral role in different aspects of a child's development. Sensory-motor development is not only foundational to the physical maturation process, but is also imperative for progress with formal learning activities. Deficits in visual-motor integration have been identified as precursors of later learning disabilities and other neurological conditions. The primary aim of this study was to determine the status of visual-motor integration functioning of a group of learners from a disadvantaged peri-urban South African community. Visual-motor integration functioning was assessed using the Developmental Test of Visual-Motor Integration (VMI) and the Goodenough-Harris Drawing Test (GHD). Three hundred and thirty-nine learners in grades 1-4 were assessed and results for the group relative to gender, chronological age and socioeconomic status are reported. For the group, the mean test age fell 16 months below the mean chronological age on the VMI. The mean GHD score for the group was about a half a standard deviation below the GHD's test norm. At school entry level, visual-motor integration was more than one standard deviation below the mean. Compared to female learners, male learners achieved significantly higher scores on the test age score of the VMI (mean difference = 8.69 months), and the intelligence coefficient score of the GHD (mean difference = 4.68). Scores on both measures increased as a function of socioeconomic status. The VMI and GHD scores were significantly correlated (r = 0.45; P < 0.01) suggesting that visual-motor integration is integral to intellectual functioning.

  17. Dissociated mean and functional connectivity BOLD signals in visual cortex during eyes closed and fixation

    PubMed Central

    Larson-Prior, Linda; Ludwikow, Marek; Zhang, Dongyang; Snyder, Abraham Z.; Gusnard, Debra L.; Raichle, Marcus E.; d'Avossa, Giovanni

    2012-01-01

    We investigated the effects of resting state type on blood oxygen level-dependent (BOLD) signal and functional connectivity in two paradigms: participants either alternated between fixation and eyes closed or maintained fixation or eyes closed throughout each scan. The BOLD signal and functional connectivity of lower and higher tiers of the visual cortical hierarchy were found to be differentially modulated during eyes closed versus fixation. Fixation was associated with greater mean BOLD signals in primary visual cortex and lower mean BOLD signals in extrastriate visual areas than periods of eyes closed. In addition, analysis of thalamocortical functional connectivity during scans in which participants maintained fixation showed synchronized BOLD fluctuations between those thalamic nuclei whose mean BOLD signal was systematically modulated during alternating epochs of eyes closed and fixation, primary visual cortex and the attention network, while during eyes closed negatively correlated fluctuations were seen between the same thalamic nuclei and extrastriate visual areas. Finally, in all visual areas the amplitude of spontaneous BOLD fluctuations was greater during eyes closed than during fixation. The dissociation between early and late tiers of visual cortex, which characterizes both mean and functionally connected components of the BOLD signal, may depend on the reorganization of thalamocortical networks. Since dissociated changes in local blood flow also characterize transitions between different stages of sleep and wakefulness (Braun AR, Balkin TJ, Wesenten NJ, Gwadry F, Carson RE, Varga M, Baldwin P, Belenky G, Herscovitch P. Science 279: 91–95, 1998), our results suggest that dissociated endogenous neural activity in primary and extrastriate cortex may represent a general aspect of brain function. PMID:22875902

  18. Adaptive learning in a compartmental model of visual cortex—how feedback enables stable category learning and refinement

    PubMed Central

    Layher, Georg; Schrodt, Fabian; Butz, Martin V.; Neumann, Heiko

    2014-01-01

    The categorization of real world objects is often reflected in the similarity of their visual appearances. Such categories of objects do not necessarily form disjunct sets of objects, neither semantically nor visually. The relationship between categories can often be described in terms of a hierarchical structure. For instance, tigers and leopards build two separate mammalian categories, both of which are subcategories of the category Felidae. In the last decades, the unsupervised learning of categories of visual input stimuli has been addressed by numerous approaches in machine learning as well as in computational neuroscience. However, the question of what kind of mechanisms might be involved in the process of subcategory learning, or category refinement, remains a topic of active investigation. We propose a recurrent computational network architecture for the unsupervised learning of categorial and subcategorial visual input representations. During learning, the connection strengths of bottom-up weights from input to higher-level category representations are adapted according to the input activity distribution. In a similar manner, top-down weights learn to encode the characteristics of a specific stimulus category. Feedforward and feedback learning in combination realize an associative memory mechanism, enabling the selective top-down propagation of a category's feedback weight distribution. We suggest that the difference between the expected input encoded in the projective field of a category node and the current input pattern controls the amplification of feedforward-driven representations. Large enough differences trigger the recruitment of new representational resources and the establishment of additional (sub-) category representations. We demonstrate the temporal evolution of such learning and show how the proposed combination of an associative memory with a modulatory feedback integration successfully establishes category and subcategory representations

  19. Longitudinal Examination of Adaptive Behavior in Autism Spectrum Disorders: Influence of Executive Function.

    PubMed

    Pugliese, Cara E; Anthony, Laura Gutermuth; Strang, John F; Dudley, Katerina; Wallace, Gregory L; Naiman, Daniel Q; Kenworthy, Lauren

    2016-02-01

    This study characterizes longitudinal change in adaptive behavior in 64 children and adolescents with autism spectrum disorder (ASD) without intellectual disability evaluated on multiple occasions, and examines whether prior estimate of executive function (EF) problems predicts future adaptive behavior scores. Compared to standardized estimates for their developmental stage, adaptive behavior in most participants was impaired and did not improve over time. Prior EF predicted later adaptive behavior in daily living skills and socialization domains after controlling for age and IQ. Self-monitoring behaviors robustly predicted later adaptive behavior in all domains (d = 0.60-0.94). Results support targeting treatment of adaptive skills in ASD, as well as the importance of assessing for EF problems that may contribute to adaptive behavior difficulties.

  20. Exploiting the User: Adapting Personas for Use in Security Visualization Design

    SciTech Connect

    Stoll, Jennifer C.; McColgin, David W.; Gregory, Michelle L.; Crow, Vernon L.; Edwards, Keith

    2007-10-29

    It has long been noted that visual representations of complex information can facilitate rapid understanding of data {citation], even with respect to ComSec applications {citation]. Recognizing that visualizations can increase usability in ComSec applications, [Zurko, Sasse] have argued that there is a need to create more usable security visualizations. (VisSec) However, usability of applications generally fall into the domain of Human Computer Interaction (HCI), which generally relies on heavy-weight user-centered design (UCD) processes. For example, the UCD process can involve many prototype iterations, or an ethnographic field study that can take months to complete. The problem is that VisSec projects generally do not have the resources to perform ethnographic field studies, or to employ complex UCD methods. They often are running on tight deadlines and budgets that can not afford standard UCD methods. In order to help resolve the conflict of needing more usable designs in ComSec, but not having the resources to employ complex UCD methods, in this paper we offer a stripped-down lighter weight version of a UCD process which can help with capturing user requirements. The approach we use is personas which a user requirements capturing method arising out of the Participatory Design philosophy [Grudin02].

  1. Webly-supervised Fine-grained Visual Categorization via Deep Domain Adaptation.

    PubMed

    Xu, Zhe; Huang, Shaoli; Zhang, Ya; Tao, Dacheng

    2016-12-08

    Learning visual representations from web data has recently attracted attention for object recognition. Previous studies have mainly focused on overcoming label noise and data bias and have shown promising results by learning directly from web data. However, we argue that it might be better to transfer knowledge from existing human labeling resources to improve performance at nearly no additional cost. In this paper, we propose a new semi-supervised method for learning via web data. Our method has the unique design of exploiting strong supervision, i.e., in addition to standard image-level labels, our method also utilizes detailed annotations including object bounding boxes and part landmarks. By transferring as much knowledge as possible from existing strongly supervised datasets to weakly supervised web images, our method can benefit from sophisticated object recognition algorithms and overcome several typical problems found in webly-supervised learning. We consider the problem of fine-grained visual categorization, in which existing training resources are scarce, as our main research objective. Comprehensive experimentation and extensive analysis demonstrate encouraging performance of the proposed approach, which, at the same time, delivers a new pipeline for fine-grained visual categorization that is likely to be highly effective for real-world applications.

  2. Accuracy and adaptation of reaching and pointing in pitched visual environments

    NASA Technical Reports Server (NTRS)

    Welch, R. B.; Post, R. B.

    1996-01-01

    Visually perceived eye level (VPEL) and the ability of subjects to reach with an unseen limb to targets placed at VPEL were measured in a statically pitched visual surround (pitchroom). VPEL was shifted upward and downward by upward and downward room pitch, respectively. Accuracy in reaching to VPEL represented a compromise between VPEL and actual eye level. This indicates that VPEL shifts reflect in part a change in perceived location of objects. When subjects were provided with terminal visual feedback about their reaching, accuracy improved rapidly. Subsequent reaching, with the room vertical, revealed a negative aftereffect (i.e., reaching errors that were opposite those made initially in the pitched room). In a second study, pointing accuracy was assessed for targets located both at VPEL and at other positions. Errors were similar for targets whether located at VPEL or elsewhere. Additionally, pointing responses were restricted to a narrower range than that of the actual target locations. The small size of reaching and pointing errors in both studies suggests that factors other than a change in perceived location are also involved in VPEL shifts.

  3. Experimental hydrodynamics of fish locomotion: functional insights from wake visualization.

    PubMed

    Drucker, Eliot G; Lauder, George V

    2002-04-01

    Despite enormous progress during the last twenty years in understanding the mechanistic basis of aquatic animal propulsion-a task involving the construction of a substantial data base on patterns of fin and body kinematics and locomotor muscle function-there remains a key area in which biologists have little information: the relationship between propulsor activity and water movement in the wake. How is internal muscular force translated into external force exerted on the water? What is the pattern of fluid force production by different fish fins (e.g., pectoral, caudal, dorsal) and how does swimming force vary with speed and among species? These types of questions have received considerable attention in analyses of terrestrial locomotion where force output by limbs can be measured directly with force plates. But how can forces exerted by animals moving through fluid be measured? The advent of digital particle image velocimetry (DPIV) has provided an experimental hydrodynamic approach for quantifying the locomotor forces of freely moving animals in fluids, and has resulted in significant new insights into the mechanisms of fish propulsion. In this paper we present ten "lessons learned" from the application of DPIV to problems of fish locomotion over the last five years. (1) Three-dimensional DPIV analysis is critical for reconstructing wake geometry. (2) DPIV analysis reveals the orientation of locomotor reaction forces. (3) DPIV analysis allows calculation of the magnitude of locomotor forces. (4) Swimming speed can have a major impact on wake structure. (5) DPIV can reveal interspecific differences in vortex wake morphology. (6) DPIV analysis can provide new insights into the limits to locomotor performance. (7) DPIV demonstrates the functional versatility of fish fins. (8) DPIV reveals hydrodynamic force partitioning among fins. (9) DPIV shows that wake interaction among fins may enhance thrust production. (10) Experimental hydrodynamic analysis can provide

  4. Estimating quality-adjusted life years from patient-reported visual functioning

    PubMed Central

    Browne, C; Brazier, J; Carlton, J; Alavi, Y; Jofre-Bonet, M

    2012-01-01

    Purpose Glaucoma is an important disease, the impacts of which on vision have been shown to have implications for patients' health-related quality of life (HRQoL). The primary aim of this study is to estimate a mapping algorithm to predict EQ-5D and SF-6D utility values based on the vision-specific measure, the 25-item Visual Functioning Questionnaire (VFQ-25), as well as the clinical measures of visual function, that is, integrated visual field, visual acuity, and contrast sensitivity. Methods Ordinary least squares (OLS), Tobit, and censored least absolute deviations were compared using data taken from the Moorfields Eye Hospital in London, to assess mapping functions to predict the EQ-5D and SF-6D from the VFQ-25, and tests of visual function. These models were compared using root mean square error (RMSE), R2, and mean absolute error (MAE). Results OLS was the best-performing model of the three compared, as this produced the lowest RMSE and MAE, and the highest R2. Conclusions The models provided initial algorithms to convert the VFQ-25 to the EQ-5D and SF-6D. Further analysis would be needed to validate the models or algorithms. PMID:22766537

  5. Visual-Functional Mismatch Between Coronary Angiography, Fractional Flow Reserve, and Quantitative Coronary Angiography.

    PubMed

    Safi, Morteza; Eslami, Vahid; Namazi, Mohammad Hasan; Vakili, Hossain; Saadat, Habib; Alipourparsa, Saeid; Adibi, Ali; Movahed, Mohammad Reza

    2016-12-01

    Anatomical and functional mismatches are not uncommon in the assessment of coronary lesions. The aim of this study was to identify clinical and lesion-specific factors affecting angiographic, anatomical, and functional mismatch in intermediate coronary lesions. In patients who underwent coronary angiography for clinical reasons, fractional flow reserve (FFR), and quantitative coronary angiography (QCA) analyses for intermediate stenotic lesions were performed simultaneously. Mismatches between the measured values were analyzed. A total of 95 intermediate lesions were assessed simultaneously by visual angiography, FFR, and QCA. The visual-FFR mismatch was found in 40% of the lesions while reverse visual-FFR mismatch was determined in nearly 14% of the lesions. Mismatch and reverse mismatch between FFR and QCA parameters were observed in 10 and 23% of the lesions. FFR value was significant in 32% of the lesions while visually significant stenosis was shown in 61% of the lesions. Among the visual-FFR reverse mismatch group, the prevalence of culprit lesions within the left anterior descending (LAD) was significantly higher than other vessels (p value < 0.02). There were high frequencies of angiographic, QCA, and functional mismatches in analyses of intermediate coronary lesions. LAD lesions showed the highest mismatch. Angiographic or QCA estimation of lesion severity has consistently resulted in inappropriate stenting of functionally nonsignificant lesions or undertreatment of significant lesions based on FFR.

  6. Age and Adaptive Functioning in Children and Adolescents with ASD: The Effects of Intellectual Functioning and ASD Symptom Severity

    ERIC Educational Resources Information Center

    Hill, Trenesha L.; Gray, Sarah A. O.; Kamps, Jodi L.; Enrique Varela, R.

    2015-01-01

    The present study examined the moderating effects of intellectual functioning and ASD symptom severity on the relation between age and adaptive functioning in 220 youth with autism spectrum disorder (ASD). Regression analysis indicated that intellectual functioning and ASD symptom severity moderated the relation between age and adaptive…

  7. Chemical Visualization of Boolean Functions: A Simple Chemical Computer

    NASA Astrophysics Data System (ADS)

    Blittersdorf, R.; Müller, J.; Schneider, F. W.

    1995-08-01

    We present a chemical realization of the Boolean functions AND, OR, NAND, and NOR with a neutralization reaction carried out in three coupled continuous flow stirred tank reactors (CSTR). Two of these CSTR's are used as input reactors, the third reactor marks the output. The chemical reaction is the neutralization of hydrochloric acid (HCl) with sodium hydroxide (NaOH) in the presence of phenolphtalein as an indicator, which is red in alkaline solutions and colorless in acidic solutions representing the two binary states 1 and 0, respectively. The time required for a "chemical computation" is determined by the flow rate of reactant solutions into the reactors since the neutralization reaction itself is very fast. While the acid flow to all reactors is equal and constant, the flow rate of NaOH solution controls the states of the input reactors. The connectivities between the input and output reactors determine the flow rate of NaOH solution into the output reactor, according to the chosen Boolean function. Thus the state of the output reactor depends on the states of the input reactors.

  8. The Association between Resting Functional Connectivity and Visual Creativity

    PubMed Central

    Li, Wenfu; Yang, Junyi; Zhang, Qinglin; Li, Gongying; Qiu, Jiang

    2016-01-01

    Resting-state functional connectivity (RSFC), the temporal correlation of intrinsic activation between different brain regions, has become one of the most fascinating field in the functional imaging studies. To better understand the association between RSFC and individual creativity, we used RSFC and the figure Torrance Tests of Creative Thinking (TTCT-F) to investigate the relationship between creativity measured by TTCT and RSFC within two different brain networks, default mode network and the cognitive control network, in a large healthy sample (304). We took the medial prefrontal cortex (MPFC) and the bilateral dorsolateral prefrontal cortices (DLPFC) to be the seed regions and investigated the association across subjects between the score of TTCT-F and the strength of RSFC between these seed regions and other voxels in the whole brain. Results revealed that the strength of RSFC with the MPFC was significantly and negatively correlated with the score of TTCT-F in the precuneus. Meanwhile, we also found that the strength of RSFC with the left DLPFC was significantly and positively correlated with the score of TTCT-F in the right DLPFC. It suggests that the decreased RSFC within DMN and the increased RSFC within CCN presents a potential interaction mechanism between different region for higher creativity. PMID:27138732

  9. Visual Imagery and False Memory for Pictures: A Functional Magnetic Resonance Imaging Study in Healthy Participants

    PubMed Central

    Stephan-Otto, Christian; Siddi, Sara; Senior, Carl; Muñoz-Samons, Daniel; Ochoa, Susana; Sánchez-Laforga, Ana María; Brébion, Gildas

    2017-01-01

    Background Visual mental imagery might be critical in the ability to discriminate imagined from perceived pictures. Our aim was to investigate the neural bases of this specific type of reality-monitoring process in individuals with high visual imagery abilities. Methods A reality-monitoring task was administered to twenty-six healthy participants using functional magnetic resonance imaging. During the encoding phase, 45 words designating common items, and 45 pictures of other common items, were presented in random order. During the recall phase, participants were required to remember whether a picture of the item had been presented, or only a word. Two subgroups of participants with a propensity for high vs. low visual imagery were contrasted. Results Activation of the amygdala, left inferior occipital gyrus, insula, and precuneus were observed when high visual imagers encoded words later remembered as pictures. At the recall phase, these same participants activated the middle frontal gyrus and inferior and superior parietal lobes when erroneously remembering pictures. Conclusions The formation of visual mental images might activate visual brain areas as well as structures involved in emotional processing. High visual imagers demonstrate increased activation of a fronto-parietal source-monitoring network that enables distinction between imagined and perceived pictures. PMID:28046076

  10. Cross-Modal Functional Reorganization of Visual and Auditory Cortex in Adult Cochlear Implant Users Identified with fNIRS.

    PubMed

    Chen, Ling-Chia; Sandmann, Pascale; Thorne, Jeremy D; Bleichner, Martin G; Debener, Stefan

    2016-01-01

    Cochlear implant (CI) users show higher auditory-evoked activations in visual cortex and higher visual-evoked activation in auditory cortex compared to normal hearing (NH) controls, reflecting functional reorganization of both visual and auditory modalities. Visual-evoked activation in auditory cortex is a maladaptive functional reorganization whereas auditory-evoked activation in visual cortex is beneficial for speech recognition in CI users. We investigated their joint influence on CI users' speech recognition, by testing 20 postlingually deafened CI users and 20 NH controls with functional near-infrared spectroscopy (fNIRS). Optodes were placed over occipital and temporal areas to measure visual and auditory responses when presenting visual checkerboard and auditory word stimuli. Higher cross-modal activations were confirmed in both auditory and visual cortex for CI users compared to NH controls, demonstrating that functional reorganization of both auditory and visual cortex can be identified with fNIRS. Additionally, the combined reorganization of auditory and visual cortex was found to be associated with speech recognition performance. Speech performance was good as long as the beneficial auditory-evoked activation in visual cortex was higher than the visual-evoked activation in the auditory cortex. These results indicate the importance of considering cross-modal activations in both visual and auditory cortex for potential clinical outcome estimation.

  11. Stereoscopic three-dimensional visualization applied to multimodal brain images: clinical applications and a functional connectivity atlas

    PubMed Central

    Rojas, Gonzalo M.; Gálvez, Marcelo; Vega Potler, Natan; Craddock, R. Cameron; Margulies, Daniel S.; Castellanos, F. Xavier; Milham, Michael P.

    2014-01-01

    Effective visualization is central to the exploration and comprehension of brain imaging data. While MRI data are acquired in three-dimensional space, the methods for visualizing such data have rarely taken advantage of three-dimensional stereoscopic technologies. We present here results of stereoscopic visualization of clinical data, as well as an atlas of whole-brain functional connectivity. In comparison with traditional 3D rendering techniques, we demonstrate the utility of stereoscopic visualizations to provide an intuitive description of the exact location and the relative sizes of various brain landmarks, structures and lesions. In the case of resting state fMRI, stereoscopic 3D visualization facilitated comprehension of the anatomical position of complex large-scale functional connectivity patterns. Overall, stereoscopic visualization improves the intuitive visual comprehension of image contents, and brings increased dimensionality to visualization of traditional MRI data, as well as patterns of functional connectivity. PMID:25414626

  12. Stereoscopic three-dimensional visualization applied to multimodal brain images: clinical applications and a functional connectivity atlas.

    PubMed

    Rojas, Gonzalo M; Gálvez, Marcelo; Vega Potler, Natan; Craddock, R Cameron; Margulies, Daniel S; Castellanos, F Xavier; Milham, Michael P

    2014-01-01

    Effective visualization is central to the exploration and comprehension of brain imaging data. While MRI data are acquired in three-dimensional space, the methods for visualizing such data have rarely taken advantage of three-dimensional stereoscopic technologies. We present here results of stereoscopic visualization of clinical data, as well as an atlas of whole-brain functional connectivity. In comparison with traditional 3D rendering techniques, we demonstrate the utility of stereoscopic visualizations to provide an intuitive description of the exact location and the relative sizes of various brain landmarks, structures and lesions. In the case of resting state fMRI, stereoscopic 3D visualization facilitated comprehension of the anatomical position of complex large-scale functional connectivity patterns. Overall, stereoscopic visualization improves the intuitive visual comprehension of image contents, and brings increased dimensionality to visualization of traditional MRI data, as well as patterns of functional connectivity.

  13. Crossmodal enhancement of visual orientation discrimination by looming sounds requires functional activation of primary visual areas: a case study.

    PubMed

    Cecere, Roberto; Romei, Vincenzo; Bertini, Caterina; Làdavas, Elisabetta

    2014-04-01

    Approaching or looming sounds are salient, potentially threatening stimuli with particular impact on visual processing. The early crossmodal effects by looming sounds (Romei, Murray, Cappe, & Thut, 2009) and their selective impact on visual orientation discrimination (Leo, Romei, Freeman, Ladavas, & Driver, 2011) suggest that these multisensory interactions may take place already within low-level visual cortices. To investigate this hypothesis, we tested a patient (SDV) with bilateral occipital lesion and spared residual portions of V1/V2. Accordingly, SDV׳s visual perimetry revealed blindness of the central visual field with some residual peripheral vision. In two experiments we tested for the influence of looming vs. receding and stationary sounds on SDV׳s line orientation discrimination (orientation discrimination experiment) and visual detection abilities (detection experiment) in the preserved or blind portions of the visual field, corresponding to spared and lesioned areas of V1, respectively. In the visual orientation discrimination experiment we found that SDV visual orientation sensitivity significantly improved for visual targets paired with looming sounds but only for lines presented in the partially preserved visual field. In the visual detection experiment, where SDV was required to simply detect the same stimuli presented in the orientation discrimination experiment, a generalised sound-induced visual improvement both in the intact and in blind portion of the visual field was observed. These results provide direct evidence that early visual areas are critically involved in crossmodal modulation of visual orientation sensitivity by looming sounds. Thus, a lesion in V1 prevents the enhancement of visual orientation sensitivity. In contrast, the same lesion does not prevent the visual detection enhancement by a sound, probably due to alternative visual pathways (e.g. retino-colliculo-extrastriate) which are usually spared in these patients and able to

  14. Reconfiguration of the Brain Functional Network Associated with Visual Task Demands.

    PubMed

    Wen, Xue; Zhang, Delong; Liang, Bishan; Zhang, Ruibin; Wang, Zengjian; Wang, Junjing; Liu, Ming; Huang, Ruiwang

    2015-01-01

    Neuroimaging studies have demonstrated that the topological properties of resting-state brain functional networks are modulated through task performances. However, the reconfiguration of functional networks associated with distinct degrees of task demands is not well understood. In the present study, we acquired fMRI data from 18 healthy adult volunteers during resting-state (RS) and two visual tasks (i.e., visual stimulus watching, VSW; and visual stimulus decision, VSD). Subsequently, we constructed the functional brain networks associated with these three conditions and analyzed the changes in the topological properties (e.g., network efficiency, wiring-cost, modularity, and robustness) among them. Although the small-world attributes were preserved qualitatively across the functional networks of the three conditions, changes in the topological properties were also observed. Compared with the resting-state, the functional networks associated with the visual tasks exhibited significantly increased network efficiency and wiring-cost, but decreased modularity and network robustness. The changes in the task-related topological properties were modulated according to the task complexity (i.e., from RS to VSW and VSD). Moreover, at the regional level, we observed that the increased nodal efficiencies in the visual and working memory regions were positively associated with the increase in task complexity. Together, these results suggest that the increased efficiency of the functional brain network and higher wiring-cost were observed to afford the demands of visual tasks. These observations provide further insights into the mechanisms underlying the reconfiguration of the brain network during task performance.

  15. Visual deprivation selectively reshapes the intrinsic functional architecture of the anterior insula subregions

    PubMed Central

    Liu, Lihua; Yuan, Congcong; Ding, Hao; Xu, Yongjie; Long, Miaomiao; Li, YanJun; Liu, Yong; Jiang, Tianzi; Qin, Wen; Shen, Wen; Yu, Chunshui

    2017-01-01

    The anterior insula (AI) is the core hub of salience network that serves to identify the most relevant stimuli among vast sensory inputs and forward them to higher cognitive regions to guide behaviour. As blind subjects were usually reported with changed perceptive abilities for salient non-visual stimuli, we hypothesized that the resting-state functional network of the AI is selectively reorganized after visual deprivation. The resting-state functional connectivity (FC) of the bilateral dorsal and ventral AI was calculated for twenty congenitally blind (CB), 27 early blind (EB), 44 late blind (LB) individuals and 50 sighted controls (SCs). The FCs of the dorsal AI were strengthened with the dorsal visual stream, while weakened with the ventral visual stream in the blind than the SCs; in contrast, the FCs of the ventral AI of the blind was strengthened with the ventral visual stream. Furthermore, these strengthened FCs of both the dorsal and ventral AI were partially negatively associated with the onset age of blindness. Our result indicates two parallel pathways that selectively transfer non-visual salient information between the deprived “visual” cortex and salience network in blind subjects. PMID:28358391

  16. The effect of visual experience on the development of functional architecture in hMT+.

    PubMed

    Ricciardi, Emiliano; Vanello, Nicola; Sani, Lorenzo; Gentili, Claudio; Scilingo, Enzo Pasquale; Landini, Luigi; Guazzelli, Mario; Bicchi, Antonio; Haxby, James V; Pietrini, Pietro

    2007-12-01

    We investigated whether the visual hMT+ cortex plays a role in supramodal representation of sensory flow, not mediated by visual mental imagery. We used functional magnetic resonance imaging to measure neural activity in sighted and congenitally blind individuals during passive perception of optic and tactile flows. Visual motion-responsive cortex, including hMT+, was identified in the lateral occipital and inferior temporal cortices of the sighted subjects by response to optic flow. Tactile flow perception in sighted subjects activated the more anterior part of these cortical regions but deactivated the more posterior part. By contrast, perception of tactile flow in blind subjects activated the full extent, including the more posterior part. These results demonstrate that activation of hMT+ and surrounding cortex by tactile flow is not mediated by visual mental imagery and that the functional organization of hMT+ can develop to subserve tactile flow perception in the absence of any visual experience. Moreover, visual experience leads to a segregation of the motion-responsive occipitotemporal cortex into an anterior subregion involved in the representation of both optic and tactile flows and a posterior subregion that processes optic flow only.

  17. Functional size of human visual area V1: a neural correlate of top-down attention.

    PubMed

    Verghese, Ashika; Kolbe, Scott C; Anderson, Andrew J; Egan, Gary F; Vidyasagar, Trichur R

    2014-06-01

    Heavy demands are placed on the brain's attentional capacity when selecting a target item in a cluttered visual scene, or when reading. It is widely accepted that such attentional selection is mediated by top-down signals from higher cortical areas to early visual areas such as the primary visual cortex (V1). Further, it has also been reported that there is considerable variation in the surface area of V1. This variation may impact on either the number or specificity of attentional feedback signals and, thereby, the efficiency of attentional mechanisms. In this study, we investigated whether individual differences between humans performing attention-demanding tasks can be related to the functional area of V1. We found that those with a larger representation in V1 of the central 12° of the visual field as measured using BOLD signals from fMRI were able to perform a serial search task at a faster rate. In line with recent suggestions of the vital role of visuo-spatial attention in reading, the speed of reading showed a strong positive correlation with the speed of visual search, although it showed little correlation with the size of V1. The results support the idea that the functional size of the primary visual cortex is an important determinant of the efficiency of selective spatial attention for simple tasks, and that the attentional processing required for complex tasks like reading are to a large extent determined by other brain areas and inter-areal connections.

  18. Cameron - Optimized Compilation of Visual Programs for Image Processing on Adaptive Computing Systems (ACS)

    DTIC Science & Technology

    2002-01-01

    the Cameron project. The goal of the Cameron project is to make FPGAs and other adaptive computer systems available to more applications programmers...loops onto an FPGA , but this is invisible. SA-C therefore makes recon- gurable processors accessible to applications programmers with no hardware...happens that for SA-C programs, the host executable off-loads the processing of loops onto an FPGA , but this is invisible. SA-C therefore makes

  19. INTEGRATING EVOLUTIONARY AND FUNCTIONAL APPROACHES TO INFER ADAPTATION AT SPECIFIC LOCI

    PubMed Central

    Storz, Jay F.; Wheat, Christopher W.

    2010-01-01

    Inferences about adaptation at specific loci are often exclusively based on the static analysis of DNA sequence variation. Ideally, population-genetic evidence for positive selection serves as a stepping-off point for experimental studies to elucidate the functional significance of the putatively adaptive variation. We argue that inferences about adaptation at specific loci are best achieved by integrating the indirect, retrospective insights provided by population-genetic analyses with the more direct, mechanistic insights provided by functional experiments. Integrative studies of adaptive genetic variation may sometimes be motivated by experimental insights into molecular function, which then provide the impetus to perform population genetic tests to evaluate whether the functional variation is of adaptive significance. In other cases, studies may be initiated by genome scans of DNA variation to identify candidate loci for recent adaptation. Results of such analyses can then motivate experimental efforts to test whether the identified candidate loci do in fact contribute to functional variation in some fitness-related phenotype. Functional studies can provide corroborative evidence for positive selection at particular loci, and can potentially reveal specific molecular mechanisms of adaptation. PMID:20500215

  20. Work function shifts of catalytic metals under hydrogen gas visualized by terahertz chemical microscopy.

    PubMed

    Kiwa, Toshihiko; Hagiwara, Takafumi; Shinomiya, Mitsuhiro; Sakai, Kenji; Tsukada, Keiji

    2012-05-21

    Terahertz chemical microscopy (TCM) was applied to visualize the distribution of the work function shift of catalytic metals under hydrogen gas. TCM measures the chemical potential on the surface of a SiO(2)/Si/sapphire sensing plate without any contact with the plate. By controlling the bias voltage between an electrode on the SiO(2)/ surface and the Si layer, the relationship between the voltage and the THz amplitude from the sensing plate can be obtained. As a demonstration, two types of structures were fabricated on the sensing plate, and the work function shifts due to catalytic reactions were visualized.

  1. Pedagogical Content Knowledge of Experienced Teachers in Physical Education: Functional Analysis of Adaptations

    ERIC Educational Resources Information Center

    Ayvazo, Shiri; Ward, Phillip

    2011-01-01

    Pedagogical content knowledge (PCK) is the teacher's ability to pedagogically adapt content to students of diverse abilities. In this study, we investigated how teachers' adaptations of instruction for individual students differed when teaching stronger and weaker instructional units. We used functional analysis (Hanley, Iwata, & McCord, 2003) of…

  2. Adaptive Functioning in Autism Spectrum Disorder during the Transition to Adulthood

    ERIC Educational Resources Information Center

    Matthews, Nicole L.; Smith, Christopher J.; Pollard, Elena; Ober-Reynolds, Sharman; Kirwan, Janet; Malligo, Amanda

    2015-01-01

    There is a dearth of research regarding adaptive functioning during the transition to adulthood in autism spectrum disorder (ASD). Profiles on the Vineland Adaptive Behavior Scales, Second Edition were examined by age and intellectual ability in 75 participants with ASD (16-58 years). Results extend previous reports of a cognitive advantage over…

  3. Correlates of Adaptive Functioning in Minimally Verbal Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Frost, Kyle M.; Hong, Natalie; Lord, Catherine

    2017-01-01

    Individuals with autism spectrum disorder (ASD) tend to have significant delays in adaptive functioning. In this study, the relationship between adaptive behavior and ASD symptomatology was investigated in minimally verbal, school-aged children with ASD (n = 333). Both the social affect (SA) and restricted and repetitive behavior (RRB) domains…

  4. The Relation between Intellectual Functioning and Adaptive Behavior in the Diagnosis of Intellectual Disability

    ERIC Educational Resources Information Center

    Tassé, Marc J.; Luckasson, Ruth; Schalock, Robert L.

    2016-01-01

    Intellectual disability originates during the developmental period and is characterized by significant limitations both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, and practical adaptive skills. In this article, we present a brief history of the diagnostic criteria of intellectual disability for both…

  5. Longitudinal Examination of Adaptive Behavior in Autism Spectrum Disorders: Influence of Executive Function

    ERIC Educational Resources Information Center

    Pugliese, Cara E.; Anthony, Laura Gutermuth; Strang, John F.; Dudley, Katerina; Wallace, Gregory L.; Naiman, Daniel Q.; Kenworthy, Lauren

    2016-01-01

    This study characterizes longitudinal change in adaptive behavior in 64 children and adolescents with autism spectrum disorder (ASD) without intellectual disability evaluated on multiple occasions, and examines whether prior estimate of executive function (EF) problems predicts future adaptive behavior scores. Compared to standardized estimates…

  6. Brief Report: Adaptive Functioning in Children with ASD, ADHD and ASD + ADHD

    ERIC Educational Resources Information Center

    Ashwood, Karen L.; Tye, Charlotte; Azadi, Bahare; Cartwright, Sally; Asherson, Philip; Bolton, Patrick

    2015-01-01

    Autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) often co-occur. Children with ASD and ADHD demonstrate deficits in adaptive functioning, yet pure and comorbid groups have not been directly compared. Vineland Adaptive Behaviour Scales (VABS-II) data were examined in boys with ASD (n = 17), ADHD (n = 31) and…

  7. The Role of Emotion Perception in Adaptive Functioning of People with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Hudepohl, Margaret B.; Robins, Diana L.; King, Tricia Z.; Henrich, Christopher C.

    2015-01-01

    Cognitive functioning has historically been used to predict adaptive outcomes of people with autism spectrum disorders; however, research shows that it is not a complete predictor. The current study explored whether emotion perception was a predictor of adaptive outcomes, and more specifically, hypothesized that emotion perception (Diagnostic…

  8. LSD alters eyes-closed functional connectivity within the early visual cortex in a retinotopic fashion.

    PubMed

    Roseman, Leor; Sereno, Martin I; Leech, Robert; Kaelen, Mendel; Orban, Csaba; McGonigle, John; Feilding, Amanda; Nutt, David J; Carhart-Harris, Robin L

    2016-08-01

    The question of how spatially organized activity in the visual cortex behaves during eyes-closed, lysergic acid diethylamide (LSD)-induced "psychedelic imagery" (e.g., visions of geometric patterns and more complex phenomena) has never been empirically addressed, although it has been proposed that under psychedelics, with eyes-closed, the brain may function "as if" there is visual input when there is none. In this work, resting-state functional connectivity (RSFC) data was analyzed from 10 healthy subjects under the influence of LSD and, separately, placebo. It was suspected that eyes-closed psychedelic imagery might involve transient local retinotopic activation, of the sort typically associated with visual stimulation. To test this, it was hypothesized that, under LSD, patches of the visual cortex with congruent retinotopic representations would show greater RSFC than incongruent patches. Using a retinotopic localizer performed during a nondrug baseline condition, nonadjacent patches of V1 and V3 that represent the vertical or the horizontal meridians of the visual field were identified. Subsequently, RSFC between V1 and V3 was measured with respect to these a priori identified patches. Consistent with our prior hypothesis, the difference between RSFC of patches with congruent retinotopic specificity (horizontal-horizontal and vertical-vertical) and those with incongruent specificity (horizontal-vertical and vertical-horizontal) increased significantly under LSD relative to placebo, suggesting that activity within the visual cortex becomes more dependent on its intrinsic retinotopic organization in the drug condition. This result may indicate that under LSD, with eyes-closed, the early visual system behaves as if it were seeing spatially localized visual inputs. Hum Brain Mapp 37:3031-3040, 2016. © 2016 Wiley Periodicals, Inc.

  9. Visualization of lymphatic vessel development, growth, and function.

    PubMed

    Pollmann, Cathrin; Hägerling, René; Kiefer, Friedemann

    2014-01-01

    Despite their important physiological and pathophysiological functions, lymphatic endothelial cells and lymphatic vessels remain less well studied compared to the blood vascular system. Lymphatic endothelium differentiates from venous blood vascular endothelium after initial arteriovenous differentiation. Only recently by the use of light sheet microscopy, the precise mechanism of separation of the first lymphatic endothelial progenitors from the cardinal vein has been described as delamination followed by mesenchymal cell migration of lymphatic endothelial cells. Dorsolaterally of the embryonic cardinal vein, lymphatic endothelial cells reaggregate to form the first lumenized lymphatic vessels, the dorsal peripheral longitudinal vessel and the more ventrally positioned primordial thoracic duct. Despite this progress in our understanding of the first lymph vessel formation, intravital observation of lymphatic vessel behavior in the intact organism, during development and in the adult, is prerequisite to a precise understanding of this tissue. Transgenic models and two-photon microscopy, in combination with optical windows, have made live intravital imaging possible: however, new imaging modalities and novel approaches promise gentler, more physiological, and longer intravital imaging of lymphatic vessels.

  10. Experiment K-7-33: Functional Neuromuscular Adaptation to Spaceflight

    NASA Technical Reports Server (NTRS)

    Edgerton, V. R.; Bodine-Fowler, S.; Hodgson, J. A.; Roy, R. R.; Kozlovskaya, I. B.

    1994-01-01

    The following data were collected from two Rhesus monkeys (782 and 2483) that were flown aboard a 14-day biosatellite mission (COSMOS 2044). The proposed study was designed to determine the effects of the absence of weight support on flexor and extensor muscles of the hindlimb. These effects were assessed morphologically and biochemically from muscle biopsies taken from a slow extensor, the soleus; a fast extensor, the medial gastrocnemius; and a fast flexor, the tibialis anterior. A second objective of this study was to determine the relative importance of activity (as determined by intramuscular electromyography, and force (as determined by joint torque) on the adaptation of muscle.

  11. Relationship Between Foveal Cone Structure and Clinical Measures of Visual Function in Patients With Inherited Retinal Degenerations

    PubMed Central

    Ratnam, Kavitha; Carroll, Joseph; Porco, Travis C.; Duncan, Jacque L.; Roorda, Austin

    2013-01-01

    Purpose. To study the relationship between cone spacing and density and clinical measures of visual function near the fovea. Methods. High-resolution images of the photoreceptor mosaic were obtained with adaptive optics scanning laser ophthalmoscopy from 26 patients with inherited retinal degenerations. Cone spacing measures were made close to or at the foveal center (mean [SD] eccentricity, 0.02 [0.03] degree; maximum eccentricity, 0.13 degree) and were converted to Z-scores, fraction of cones, and percentage-of-cones-below-average compared with normal values for each location (based on 37 age-similar visually normal eyes). Z-scores and percentage of cones below average were compared with best-corrected visual acuity (VA) and foveal sensitivity. Results. Visual acuity was significantly correlated with cone spacing (Spearman rank correlation ρ = −0.60, P = 0.003) and was preserved (≥80 letters), despite cone density measures that were 52% below normal. Foveal sensitivity showed significant correlation with cone spacing (ρ = −0.47, P = 0.017) and remained normal (≥35 decibels), despite density measures that were approximately 52% to 62% below normal. Conclusions. Cone density was reduced by up to 62% below normal at or near the fovea in eyes with VA and sensitivity that remained within normal limits. Despite a significant correlation with foveal cone spacing, VA and sensitivity are insensitive indicators of the integrity of the foveal cone mosaic. Direct, objective measures of cone structure may be more sensitive indicators of disease severity than VA or foveal sensitivity in eyes with inherited retinal degenerations. (ClinicalTrials.gov number, NCT00254605.) PMID:23908179

  12. Visual deprivation leads to gait adaptations that are age- and context-specific: II. Kinematic parameters.

    PubMed

    Hallemans, Ann; Beccu, Sofie; Van Loock, Kelly; Ortibus, Els; Truijen, Steven; Aerts, Peter

    2009-10-01

    Significant differences exist between eyes open (EO) and eyes closed (EC) conditions in postural sway, self-selected dimensionless walking speed and duration of double support in both children and adults. The decrease in speed could be attributed to a decrease in dimensionless stride length. The question remains whether the slower gait is a reflection of fundamental changes in movement control in the absence of vision or it results from uncertainty or fear of falling. Studying the differences in foot and ankle kinematics between the two conditions may provide further information. In this study we compare the impact of visual deprivation on joint kinematics during locomotion in adults and children. Visual deprivation had a significant effect on the gait pattern of healthy children and adults. Differences included a more backward leaning position of the trunk, limited movement in the pelvis, reduced hip adduction during stance, increased flexion of the knee related to flat foot contact and reduced ankle plantar flexion at push-off. These differences indicate a more cautious walking strategy in the absence of vision, probably resulting from postural control problems. Although age also had a significant effect on gait in both EO and EC conditions, adults and children show little differences in their kinematic response to blindfolding.

  13. Exposure to Organic Solvents Used in Dry Cleaning Reduces Low and High Level Visual Function

    PubMed Central

    Jiménez Barbosa, Ingrid Astrid

    2015-01-01

    Purpose To investigate whether exposure to occupational levels of organic solvents in the dry cleaning industry is associated with neurotoxic symptoms and visual deficits in the perception of basic visual features such as luminance contrast and colour, higher level processing of global motion and form (Experiment 1), and cognitive function as measured in a visual search task (Experiment 2). Methods The Q16 neurotoxic questionnaire, a commonly used measure of neurotoxicity (by the World Health Organization), was administered to assess the neurotoxic status of a group of 33 dry cleaners exposed to occupational levels of organic solvents (OS) and 35 age-matched non dry-cleaners who had never worked in the dry cleaning industry. In Experiment 1, to assess visual function, contrast sensitivity, colour/hue discrimination (Munsell Hue 100 test), global motion and form thresholds were assessed using computerised psychophysical tests. Sensitivity to global motion or form structure was quantified by varying the pattern coherence of global dot motion (GDM) and Glass pattern (oriented dot pairs) respectively (i.e., the percentage of dots/dot pairs that contribute to the perception of global structure). In Experiment 2, a letter visual-search task was used to measure reaction times (as a function of the number of elements: 4, 8, 16, 32, 64 and 100) in both parallel and serial search conditions. Results Dry cleaners exposed to organic solvents had significantly higher scores on the Q16 compared to non dry-cleaners indicating that dry cleaners experienced more neurotoxic symptoms on average. The contrast sensitivity function for dry cleaners was significantly lower at all spatial frequencies relative to non dry-cleaners, which is consistent with previous studies. Poorer colour discrimination performance was also noted in dry cleaners than non dry-cleaners, particularly along the blue/yellow axis. In a new finding, we report that global form and motion thresholds for dry cleaners

  14. Functional connectivity of visual cortex in the blind follows retinotopic organization principles.

    PubMed

    Striem-Amit, Ella; Ovadia-Caro, Smadar; Caramazza, Alfonso; Margulies, Daniel S; Villringer, Arno; Amedi, Amir

    2015-06-01

    Is visual input during critical periods of development crucial for the emergence of the fundamental topographical mapping of the visual cortex? And would this structure be retained throughout life-long blindness or would it fade as a result of plastic, use-based reorganization? We used functional connectivity magnetic resonance imaging based on intrinsic blood oxygen level-dependent fluctuations to investigate whether significant traces of topographical mapping of the visual scene in the form of retinotopic organization, could be found in congenitally blind adults. A group of 11 fully and congenitally blind subjects and 18 sighted controls were studied. The blind demonstrated an intact functional connectivity network structural organization of the three main retinotopic mapping axes: eccentricity (centre-periphery), laterality (left-right), and elevation (upper-lower) throughout the retinotopic cortex extending to high-level ventral and dorsal streams, including characteristic eccentricity biases in face- and house-selective areas. Functional connectivity-based topographic organization in the visual cortex was indistinguishable from the normally sighted retinotopic functional connectivity structure as indicated by clustering analysis, and was found even in participants who did not have a typical retinal development in utero (microphthalmics). While the internal structural organization of the visual cortex was strikingly similar, the blind exhibited profound differences in functional connectivity to other (non-visual) brain regions as compared to the sighted, which were specific to portions of V1. Central V1 was more connected to language areas but peripheral V1 to spatial attention and control networks. These findings suggest that current accounts of critical periods and experience-dependent development should be revisited even for primary sensory areas, in that the connectivity basis for visual cortex large-scale topographical organization can develop without any

  15. Functional imaging of cat primary visual cortex with optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Rajagopalan, Uma M.; Takaoka, Hideyuki; Homma, Ryota; Kadono, Hirofumi; Tanifuji, Manabu

    2002-06-01

    We report the application of Optical coherence tomography (OCT) for visualizing a one dimensional depth resolved functional structure of cat brain in vivo. The OCT system is based on the known fact that neural activation induces structural changes such as capillary dilation and cellular swelling. Detecting these changes as an amplitude change of the scattered light, an OCT signal reflecting neural activity i.e., fOCT (functional OCT) could be obtained. Experiments have been done to obtain a depth resolved stimulus-specific profile of activation in cat visual cortex. Our results in one dimension indicate that indeed an orientation dependent functional signal could be obtained. Further, we show that this depth resolved fOCT signal is well correlated with the stimulus dependent column determined by OISI. Based on the results, the smallest functional unit in depth, resolved by the proposed system is around 40 micrometers . We are extending our system to perform two dimensional functional imaging.