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Results 301 - 350 of 1565
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Aaen-Stockdale Craig - - 2008
Humans with amblyopia display anomalous performance for global motion discrimination. Attempts have been made to rule out an explanation based solely on the visibility loss in lower visual areas. However, it remains a possibility that the altered scale over which local motion is processed in V1 might lead to reduced ...
Conlon Elizabeth - - 2008
Sensitivity to the attributes of a stimulus (form or motion) and accuracy when detecting rapidly presented stimulus information were measured in older (N = 36) and younger (N = 37) groups. Before and after practice, the older group was significantly less sensitive to global motion (but not to form) and ...
Bachthaler Sven - - 2008
This paper introduces orthogonal vector field visualization on 2D manifolds: a representation by lines that are perpendicular to the input vector field. Line patterns are generated by line integral convolution (LIC). This visualization is combined with animation based on motion along the vector field. This decoupling of the line direction ...
Shirai Nobu N Department of Psychology, Tokyo Metropolitan University, 1-1 minamiohsawa, Hachiohji, Tokyo, 192-0397, Japan. - - 2008
Sensitivity to rotational motion, one of the fundamental components of optic flow, was tested in infants aged 2 and 3 months. The infants in both groups showed significant sensitivity to rotational motion only in the high-speed condition (10.62 degrees/s). There was no significant increase in motion sensitivity between 2 and ...
Moo Lauren R - - 2008
Human motion processing region MT + is retinotopically organized with perception of and attention to motion in the right visual field preferentially associated with left MT + activity and vice versa. However, the degree to which MT + is crucial for motion processing is uncertain. We report an epilepsy patient ...
Handa T - - 2008
To investigate the neural mechanisms of motion-defined shape processing, we recorded single unit activity in the middle temporal area (MT) while monkeys performed a shape discrimination task under the shape-from-motion (SFM) condition, where a motion cue is critical for shape perception. About 40% of MT neurons responded differentially to shapes ...
Mareschal Isabelle - - 2008
Visual sensitivity is reduced in the periphery for many discrimination tasks. Previously it has been reported that motion coherence thresholds are higher for dot stimuli presented in the periphery, a finding that could arise either from (a) impaired motion integration or (b) from motion integrators inheriting more noisy local directional ...
Pei Y C - - 2008
The visual and somatosensory systems have been shown to process spatial information similarly. Here we investigate tactile motion processing using stimuli whose perceptual properties have been well established in vision research, namely superimposed gratings (plaids), barber poles, and bar fields. In both modalities, information about stimulus motion (speed and direction) ...
Morrone Maria Concetta - - 2008
We report here two cases of two young diplegic patients with cystic periventricular leukomalacia who systematically, and with high sensitivity, perceive translational motion of a random-dot display in the opposite direction. The apparent inversion was specific for translation motion: Rotation and expansion motion were perceived correctly, with normal sensitivity. It ...
Kourtzi Zoe - - 2008
Understanding dynamic events entails the integration of information about form and motion that is crucial for fast and successful interactions in complex environments. A striking example of our sensitivity to dynamic information is our ability to recognize animate figures by the way they move and infer motion from still images. ...
Ilg Uwe J - - 2008
What is the main purpose of visual motion processing? One very important aspect of motion processing is definitively the generation of smooth pursuit eye movements. These eye movements avoid motion blur of moving objects which would obstruct the analysis of the objects' visual details. However, these eye movements can only ...
Nardini Marko M Centre for Brain and Cognitive Development, Birkbeck College, University of London, London, UK. - - 2008
Mammalian navigation depends both on visual landmarks and on self-generated (e.g., vestibular and proprioceptive) cues that signal the organism's own movement [1-5]. When these conflict, landmarks can either reset estimates of self-motion or be integrated with them [6-9]. We asked how humans combine these information sources and whether children, who ...
Lorteije Jeannette A M - - 2008
Human psychophysical and electrophysiological evidence suggests at least two separate visual motion pathways, one tuned to a lower and one tuned to a broader and partly overlapping range of higher speeds. It remains unclear whether these two different channels are represented by different cortical areas or by sub-populations within a ...
Vandenbroucke Myriam W G - - 2008
Research on visual perception in Autism Spectrum Disorder (ASD) tries to reveal the underlying mechanisms of aberrant local and global processing. Global motion perception is one way to study this aspect of ASD. We used plaid motion stimuli, which can be perceived as a coherently moving pattern, requiring feature integration, ...
Spering Miriam - - 2008
Smooth pursuit eye movements are continuous, slow rotations of the eyes that allow us to follow the motion of a visual object of interest. These movements are closely related to sensory inputs from the visual motion processing system. To track a moving object in the natural environment, its motion first ...
Rizzo Matthew M Department of Neurology, The University of Iowa College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242, USA. - - 2008
Perception of visual motion includes a first-order mechanism sensitive to luminance changes and a second-order motion mechanism sensitive to contrast changes. We studied neural substrates for these motion types in 142 subjects with visual cortex lesions, 68 normal controls and 28 brain lesion controls. On first-order motion, the visual cortex ...
Oruc Ipek - - 2008
A large body of work now exists that demonstrates the interaction between different sensory modalities when they are integrated into a single coherent percept. Yet, it is not yet clear whether attention plays a critical role in such crossmodal interactions. We investigated the effect of attention on the crossmodal integration ...
Thompson Benjamin - - 2008
Amblyopes exhibit a global motion anomaly that implicates processing beyond the local motion analysis of V1 possibly involving areas MT and MST in the extra-striate cortex. Here, we sought to further investigate this deficit by measuring the perception of moving plaid stimuli by amblyopic observers, since there is good physiological ...
Hanes Douglas A - - 2008
The object of this study is to mathematically specify important characteristics of visual flow during translation of the eye for the perception of depth and self-motion. We address various strategies by which the central nervous system may estimate self-motion and depth from motion parallax, using equations for the visual velocity ...
Garcia Javier O - - 2008
Researchers have argued that biological motion perception from point-light animations is resolved from stationary form information. To determine whether motion is required for biological motion perception, we measured discrimination thresholds at isoluminance. Whereas simple direction discriminations falter at isoluminance, biological motion perception fails entirely. However, when performance is measured as ...
Alink Arjen - - 2008
The brain is capable of integrating motion information arising from visual and auditory input. Such integration between sensory modalities can aid one another and helps to stabilize the motion percept. However, if motion information differs between sensory modalities, it can also result in an illusory auditory motion percept. This phenomenon ...
Silvanto Juha - - 2008
Transcranial magnetic stimulation (TMS) is increasingly used to modify brain activity noninvasively and to study brain-behavior relations. However, results can be variable and the conditions that affect the functional efficacy of TMS remain unclear. Here we show that on-line TMS can either facilitate or suppress perceptual functions depending on the ...
Joesch Maximilian - - 2008
The crystalline-like structure of the optic lobes of the fruit fly Drosophila melanogaster has made them a model system for the study of neuronal cell-fate determination, axonal path finding, and target selection. For functional studies, however, the small size of the constituting visual interneurons has so far presented a formidable ...
Law Chi-Tat CT Department of Neuroscience, 116 Johnson Pavilion, 3610 Hamilton Walk, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6074, - - 2008
This study aimed to identify neural mechanisms that underlie perceptual learning in a visual-discrimination task. We trained two monkeys (Macaca mulatta) to determine the direction of visual motion while we recorded from their middle temporal area (MT), which in trained monkeys represents motion information that is used to solve the ...
Deutschländer Angela - - 2008
Patients with unilateral vestibular failure (UVF) experience oscillopsia (apparent motion of the visual scene) during rapid head movements due to increased retinal slip caused by vestibulo-ocular reflex impairment. Oscillopsia is always smaller than the net retinal slip and decreases over time in patients with acquired vestibular loss; this correlates with ...
Zabouri N - - 2008
In cats, it is generally believed that the visual part of the anterior ectosylvian cortex (AEV) is involved in motion integration. It receives a substantial proportion of its afferents from cortical (e.g. lateral suprasylvian cortex) and subcortical (e.g. lateral posterior-pulvinar complex) areas known to participate in complex motion analysis. It ...
Rosenberg Ari - - 2008
Motion transparency occurs when multiple object velocities are present within a local region of retinotopic space. Transparent signals can carry information useful in the segmentation of moving objects and in the extraction of three-dimensional structure from relative motion cues. However, the physiological substrate underlying the detection of motion transparency is ...
Winawer Jonathan - - 2008
A photograph of an action can convey a vivid sense of motion. Does the inference of motion from viewing a photograph involve the same neural and psychological representations used when one views physical motion? In this study, we tested whether implied motion is represented by the same direction-selective signals involved ...
Jagaroo Vinoth - - 2008
Current augmentative and alternative communication technologies allow animation within visual symbol displays. Clinicians therefore have the option of incorporating motion-based effects into AAC displays. Yet there is no research in the field of AAC to guide this clinical decision-making, in terms of the number or types of animated symbols that ...
Peters Richard A - - 2008
Animal signals are constrained by the environment in which they are transmitted and the sensory systems of receivers. Detection of movement-based signals is particularly challenging against the background of wind-blown plants. The Australian lizard Amphibolurus muricatus has recently been shown to compensate for greater plant motion by prolonging the introductory ...
Silvanto Juha - - 2008
By making use of the phenomenon that the effects of transcranial magnetic stimulation (TMS) are dependent on the initial cortical excitability, we show that TMS can reveal the properties of distinct neural populations within the stimulated region. Visual adaptation to either simple translational or radial motion was used to manipulate ...
Hayashi Ryusuke - - 2008
Brief movements of a large-field visual stimulus elicit short-latency tracking eye movements termed "ocular following responses" (OFRs). To address the question of whether OFRs can be elicited by purely binocular motion signals in the absence of monocular motion cues, we measured OFRs from monkeys using dichoptic motion stimuli, the monocular ...
Peters Richard - - 2008
Understanding the evolution of animal signals has to include consideration of the structure of signal and noise, and the sensory mechanisms that detect the signals. Considerable progress has been made in understanding sounds and colour signals, however, the degree to which movement-based signals are constrained by the particular patterns of ...
Harris Julie M - - 2008
Induced motion, the apparent motion of an object when a nearby object moves, has been shown to occur in a variety of different conditions, including motion in depth. Here we explore whether similar patterns of induced motion result from induction in a lateral direction (frontoparallel motion) or induction in depth. ...
Barthélemy Frédéric V - - 2008
Integrating information is essential to measure the physical 2D motion of a surface from both ambiguous local 1D motion of its elongated edges and non-ambiguous 2D motion of its features such as corners or texture elements. The dynamics of this motion integration shows a complex time course as read from ...
Chen Yue - - 2008
Schizophrenia is a brain disorder that spans across biological and behavioral levels. The links between altered neural circuitry and abnormal behaviors are yet to be understood. Visual motion perception has been established in basic neuroscience and may provide an opportunity to link different levels of brain functions in schizophrenia. Center-surround ...
Freitag Christine M - - 2008
In individuals with autism or autism-spectrum-disorder (ASD), conflicting results have been reported regarding the processing of biological motion tasks. As biological motion perception and recognition might be related to impaired imitation, gross motor skills and autism specific psychopathology in individuals with ASD, we performed a functional MRI study on biological ...
Simion Francesca - - 2008
An inborn predisposition to attend to biological motion has long been theorized, but had so far been demonstrated only in one animal species (the domestic chicken). In particular, no preference for biological motion was reported for human infants of <3 months of age. We tested 2-day-old babies' discrimination after familiarization ...
Thurman Steven M - - 2008
Humans are remarkably good at recognizing biological motion, even when depicted as point-light animations. There is currently some debate as to the relative importance of form and motion cues in the perception of biological motion from the simple dot displays. To investigate this issue, we adapted the "Bubbles" technique, most ...
Thompson Benjamin - - 2008
Although a number of low-level visual deficits in amblyopia have been identified, it is still unclear to what extent these deficits extend throughout the visual processing hierarchy. Biological motion perception can be a useful measure of local and global visual processing since the point-light stimuli that are often used to ...
Dyde Richard T - - 2008
Eye, head, and body movement are intimately linked. During self-motion, the eyes track objects by a combination of vestibular reflexes and smooth pursuit eye movements but although the world appears stable during saccadic gaze changes, it does not appear stable during physical self-motion. We determined the amount by which a ...
Laubrock Jochen - - 2008
Neuronal activity in area LIP is correlated with the perceived direction of ambiguous apparent motion (Z. M. Williams, J. C. Elfar, E. N. Eskandar, L. J. Toth, & J. A. Assad, 2003). Here we show that a similar correlation exists for small eye movements made during fixation. A moving dot ...
Antal A - - 2008
The posterior cingulate cortex (PCC) is involved in higher order sensory and sensory-motor integration while the planum temporale/parietal operculum (PT/PO) junction takes part in auditory motion and vestibular processing. Both regions are activated during different types of visual stimulation. Here, we describe the response characteristics of the PCC and PT/PO ...
Aaen-Stockdale Craig - - 2008
Previous work investigating whether biological motion is supported by local second-order motion has been contradictory, with different groups finding either a difference or no difference in performance compared to that obtained with first-order stimuli. Here we show psychophysically, using randomized-polarity and contrast-modulated stimuli, that detection of second-order biological motion walkers ...
Imura Tomoko - - 2008
An expanding object, which may represent an approaching motion, is easier to detect than a contracting one, which may represent a receding object. To confirm the generality of asymmetry in the detection of approaching and receding motions, we focused on the perception of apparent motion in depth created by moving ...
Freeman Elliot - - 2008
Ambiguous stimuli can look different in different contexts. Here we demonstrate that subjective appearance of motion depends not only on current visual input but critically on which aspects of the context are attended. Observers fixated a central oblique test grating flanked by two pairs of orthogonally oriented context gratings arranged ...
Rucci Michele - - 2008
Perception and motor control are often regarded as two separate branches of neuroscience. Like most species, however, humans are not passively exposed to the incoming flow of sensory data, but actively seek useful information. By shaping input signals in ways that simplify perceptual tasks, behavior might play an important role ...
Holly Jan E - - 2008
Illusory perceptions of motion and orientation arise during human centrifuge runs without vision. Asymmetries have been found between acceleration and deceleration, and between forward-facing and backward-facing runs. Perceived roll tilt has been studied extensively during upright fixed-carriage centrifuge runs, and other components have been studied to a lesser extent. Certain, ...
Prins Nicolaas - - 2008
It has been suggested that correspondence matching in long-range motion is mediated by a perceptually high-level, 'intelligent' system. This suggestion is based on findings that long-range motion can be perceived between stimuli that could not be detected by lower-level motion mechanisms acting on Fourier motion energy, and that correspondence matching ...
Souman Jan L - - 2008
Smooth pursuit eye movements add motion to the retinal image. To compensate, the visual system can combine estimates of pursuit velocity and retinal motion to recover motion with respect to the head. Little attention has been paid to the temporal characteristics of this compensation process. Here, we describe how the ...
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