The Perception of Structure from Visual Motion in Monkey and Man

1990 ◽  
Vol 2 (4) ◽  
pp. 306-319 ◽  
Author(s):  
R. M. Siegel ◽  
R. A. Andersen
Keyword(s):  
Visual Motion ◽  
Human Subjects ◽  
Cognitive Strategies ◽  
Three Dimensional ◽  
Reaction Time Task ◽  
Neural Mechanism ◽  
Primate Species ◽  
Motion Stimulus ◽  
Extensive Training ◽  
Surface Representations

The ability to perceive structure using motion information was examined using a reaction time task with two primate species. Homo sapien and Macaca mulatta subjects were quantitatively tested under identical conditions to detect the change from a control unstructured to a test structured motion stimulus. The structures underlying the test were rotations of a plane, expansion of a plane, and a rotation of a three-dimensional cylinder. On many of the stimulus conditions, the two species performed similarly, although there were some species differences. These differences may be due to the extensive training of the monkeys or the use of different cognitive strategies by the human subjects. These data provide support for the existence of a neural mechanism that uses flow fields to construct two- or three-dimensional surface representations.

scholarly journals Canine sense of quantity: evidence for numerical ratio-dependent activation in parietotemporal cortex

2019 ◽  
Vol 15 (12) ◽  
pp. 20190666 ◽  
Author(s):  
Lauren S. Aulet ◽  
Veronica C. Chiu ◽  
Ashley Prichard ◽  
Mark Spivak ◽  
Stella F. Lourenco ◽  
...  
Keyword(s):  
Neural Mechanism ◽  
Number System ◽  
Neural Mechanisms ◽  
Primate Species ◽  
Approximate Number System ◽  
Numerical Estimation ◽  
Extensive Training ◽  
Ratio Dependent ◽  
Neural Underpinnings ◽  
Number Perception

The approximate number system (ANS), which supports the rapid estimation of quantity, emerges early in human development and is widespread across species. Neural evidence from both human and non-human primates suggests the parietal cortex as a primary locus of numerical estimation, but it is unclear whether the numerical competencies observed across non-primate species are subserved by similar neural mechanisms. Moreover, because studies with non-human animals typically involve extensive training, little is known about the spontaneous numerical capacities of non-human animals. To address these questions, we examined the neural underpinnings of number perception using awake canine functional magnetic resonance imaging. Dogs passively viewed dot arrays that varied in ratio and, critically, received no task-relevant training or exposure prior to testing. We found evidence of ratio-dependent activation, which is a key feature of the ANS, in canine parietotemporal cortex in the majority of dogs tested. This finding is suggestive of a neural mechanism for quantity perception that has been conserved across mammalian evolution.

scholarly journals Canine sense of quantity: evidence for numerical ratio-dependent activation in parietotemporal cortex

2019 ◽  
Author(s):  
Lauren S. Aulet ◽  
Veronica C. Chiu ◽  
Ashley Prichard ◽  
Mark Spivak ◽  
Stella F. Lourenco ◽  
...  
Keyword(s):  
Neural Mechanism ◽  
Number System ◽  
Neural Mechanisms ◽  
Primate Species ◽  
Approximate Number System ◽  
Numerical Estimation ◽  
Extensive Training ◽  
Ratio Dependent ◽  
Neural Underpinnings ◽  
Number Perception

AbstractThe approximate number system, which supports the rapid estimation of quantity, emerges early in human development and is widespread across species. Neural evidence from both human and non-human primates suggests the parietal cortex as a primary locus of numerical estimation, but it is unclear whether the numerical competencies observed across non-primate species are subserved by similar neural mechanisms. Moreover, because studies with non-human animals typically involve extensive training, little is known about the spontaneous numerical capacities of non-human animals. To address these questions, we examined the neural underpinnings of number perception using awake canine functional magnetic resonance imaging. Dogs passively viewed dot arrays that varied in ratio and, critically, received no task-relevant training or exposure prior to testing. We found evidence of ratio-dependent activation, which is a key feature of the approximate number system, in canine parietotemporal cortex in the majority of dogs tested. This finding is suggestive of a neural mechanism for quantity perception that has been conserved across mammalian evolution.

Perceptual, Oculomotor, and Neural Responses to Moving Color Plaids

Perception ◽  
1998 ◽  
Vol 27 (6) ◽  
pp. 681-709 ◽  
Author(s):  
Karen R Dobkins ◽  
Gene R Stoner ◽  
Thomas D Albright
Keyword(s):  
Eye Movements ◽  
Visual Motion ◽  
Human Subjects ◽  
Phase Relationship ◽  
Neural Mechanism ◽  
Luminance Contrast ◽  
Motion Processing ◽  
Motion Coherence ◽  
Bright Green ◽  
Phase Relationships

Moving plaids constructed from two achromatic gratings of identical luminance contrast are known to yield a percept of coherent pattern motion, as are plaids constructed from two identical chromatic (eg isoluminant red/green) gratings. To examine the interactive influences of chromatic and luminance contrast on the integration of visual motion signals, we constructed plaids with gratings that possessed both forms of contrast. We used plaids of two basic types, which differed with respect to the phase relationship between chromatic and luminance modulations (after Kooi et al, 1992 Perception21 583–598). One plaid type (‘symmetric’) was made from component gratings that had identical chromatic/luminance phase relationships (eg both components were red-bright/green-dark modulation). The second plaid type (‘asymmetric’) was made from components that had complimentary phase relationships (ie one red-bright/green-dark grating and one green-bright/red-dark grating). Human subjects reported that the motion of symmetric plaids was perceptually coherent, while the components of asymmetric plaids failed to cohere. We also recorded eye movements elicited by both types of plaids to determine if they are similarly affected by these image cues for motion coherence. Results demonstrate that, under many conditions, eye movements elicited by perceptually coherent vs noncoherent plaids are distinguishable from one another. To reveal the neural bases of these perceptual and oculomotor phenomena, we also recorded the responses of neurons in the middle temporal visual area (area MT) of macaque visual cortex. Here we found that individual neurons exhibited differential tuning to symmetric vs asymmetric plaids. These neurophysiological results demonstrate that the neural mechanism for motion coherence is sensitive to the phase relationship between chromatic and luminance contrast, a finding which has implications for interactions between ‘color’ and ‘motion’ processing streams in the primate visual system.

Three-Dimensional Reconstruction of Native Androctonus Australis Hemocyanin

1990 ◽  
Vol 48 (1) ◽  
pp. 452-453
Author(s):  
Nicolas Boisset ◽  
Jean-Christophe Taveau ◽  
Jean Lamy ◽  
Terence Wagenknecht ◽  
Michael Radermacher ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Body ◽  
Body Surface ◽  
Three Dimensional ◽  
Staining Technique ◽  
Three Dimensional Reconstruction ◽  
Dimensional Reconstruction ◽  
View Reconstruction ◽  
Surface Representations ◽  
Top View

Hemocyanin, the respiratory pigment of the scorpion Androctonus australis is composed of 24 kidney shaped subunits. A model of architecture supported by many indirect arguments has been deduced from electron microscopy (EM) and immuno-EM. To ascertain, the disposition of the subunits within the oligomer, the 24mer was submitted to three-dimensional reconstruction by the method of single-exposure random-conical tilt series.A sample of native hemocyanin, prepared with the double layer negative staining technique, was observed by transmisson electron microscopy under low-dose conditions. Six 3D-reconstructions were carried out indenpendently from top, side and 45°views. The results are composed of solid-body surface representations, and slices extracted from the reconstruction volume.The main two characters of the molecule previously reported by Van Heel and Frank, were constantly found in the solid-body surface representations. These features are the presence of two different faces called flip and flop and a rocking of the molecule around an axis passing through diagonnally opposed hexamers. Furthermore, in the solid-body surface of the top view reconstruction, the positions and orientations of the bridges connecting the half molecules were found in excellent agreement with those predicted by the model.

scholarly journals Crowd behaviour during high-stress evacuations in an immersive virtual environment

2016 ◽  
Vol 13 (122) ◽  
pp. 20160414 ◽  
Author(s):  
Mehdi Moussaïd ◽  
Mubbasir Kapadia ◽  
Tyler Thrash ◽  
Robert W. Sumner ◽  
Markus Gross ◽  
...  
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Human Subjects ◽  
High Stress ◽  
Three Dimensional ◽  
Real Life ◽  
Social Conventions ◽  
Emergency Situations ◽  
Crowd Behaviour ◽  
The Individual

Understanding the collective dynamics of crowd movements during stressful emergency situations is central to reducing the risk of deadly crowd disasters. Yet, their systematic experimental study remains a challenging open problem due to ethical and methodological constraints. In this paper, we demonstrate the viability of shared three-dimensional virtual environments as an experimental platform for conducting crowd experiments with real people. In particular, we show that crowds of real human subjects moving and interacting in an immersive three-dimensional virtual environment exhibit typical patterns of real crowds as observed in real-life crowded situations. These include the manifestation of social conventions and the emergence of self-organized patterns during egress scenarios. High-stress evacuation experiments conducted in this virtual environment reveal movements characterized by mass herding and dangerous overcrowding as they occur in crowd disasters. We describe the behavioural mechanisms at play under such extreme conditions and identify critical zones where overcrowding may occur. Furthermore, we show that herding spontaneously emerges from a density effect without the need to assume an increase of the individual tendency to imitate peers. Our experiments reveal the promise of immersive virtual environments as an ethical, cost-efficient, yet accurate platform for exploring crowd behaviour in high-risk situations with real human subjects.

Stimulus Specificity and Temporal Dynamics of Working Memory for Visual Motion

2003 ◽  
Vol 90 (4) ◽  
pp. 2757-2762 ◽  
Author(s):  
Tatiana Pasternak ◽  
Daniel Zaksas
Keyword(s):  
Visual Motion ◽  
Temporal Dynamics ◽  
Random Motion ◽  
Neural Mechanisms ◽  
Precise Location ◽  
Storage Mechanism ◽  
Motion Stimulus ◽  
Selective Interference ◽  
Stimulus Specificity ◽  
Stimulus Direction

When asked to compare two moving stimuli separated by a delay, observers must not only identify stimulus direction but also store it in memory. We examined the properties of this storage mechanism in two macaque monkeys by sequentially presenting two random-dot stimuli, sample and test, in opposite hemifields and introducing a random-motion mask during the delay. The mask interfered with performance only at the precise location of the test, 100–200 ms after the start of the delay, and when its size and speed matched those of the remembered sample. This selective interference suggests that the representation of the motion stimulus in memory preserves its direction, speed, and size and is most fragile shortly after the completion of the encoding phase of the task. This precise preservation of sensory attributes of the motion stimulus suggests that the neural mechanisms involved in the processing of visual motion may also be involved in its storage.

Human Updating of Visual Motion Direction During Head Rotations

2008 ◽  
Vol 99 (5) ◽  
pp. 2558-2576
Author(s):  
Mario Ruiz-Ruiz ◽  
Julio C. Martinez-Trujillo
Keyword(s):  
Visual Motion ◽  
Human Subjects ◽  
Head Tilt ◽  
Head Rotation ◽  
Three Dimensions ◽  
Spatial Updating ◽  
Motion Direction ◽  
Direction Discrimination ◽  
Head Rotations ◽  
Stimulus Direction

Previous studies have demonstrated that human subjects update the location of visual targets for saccades after head and body movements and in the absence of visual feedback. This phenomenon is known as spatial updating. Here we investigated whether a similar mechanism exists for the perception of motion direction. We recorded eye positions in three dimensions and behavioral responses in seven subjects during a motion task in two different conditions: when the subject's head remained stationary and when subjects rotated their heads around an anteroposterior axis (head tilt). We demonstrated that after head-tilt subjects updated the direction of saccades made in the perceived stimulus direction (direction of motion updating), the amount of updating varied across subjects and stimulus directions, the amount of motion direction updating was highly correlated with the amount of spatial updating during a memory-guided saccade task, subjects updated the stimulus direction during a two-alternative forced-choice direction discrimination task in the absence of saccadic eye movements (perceptual updating), perceptual updating was more accurate than motion direction updating involving saccades, and subjects updated motion direction similarly during active and passive head rotation. These results demonstrate the existence of an updating mechanism for the perception of motion direction in the human brain that operates during active and passive head rotations and that resembles the one of spatial updating. Such a mechanism operates during different tasks involving different motor and perceptual skills (saccade and motion direction discrimination) with different degrees of accuracy.

scholarly journals Depths and limits of spontaneous categorization in a family dog

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Claudia Fugazza ◽  
Ádám Miklósi
Keyword(s):  
Experimental Design ◽  
Vocabulary Knowledge ◽  
Human Studies ◽  
Primate Species ◽  
Perceptual Similarity ◽  
The Novel ◽  
Specific Training ◽  
Laboratory Conditions ◽  
Extensive Training ◽  
Physical Resemblance

AbstractCategorization has been tested in non-human animals after extensive training procedures under laboratory conditions and it is assumed that in non-primate species categorization relies on perceptual similarity. We report evidence of the ability to categorize objects in absence of specific training in a family dog with vocabulary knowledge of multiple toys, including exemplars of 4 categories. Our experimental design was devised to test categorization in absence of specific training and based on the spontaneously learned vocal labels of the categories, a condition that mirrors human studies more than previous experiments on non-human animals. We also observed that the dog’s categorization skills were more accurate when, prior to the categorization test, she was given the opportunity to play with the novel exemplars, suggesting that category representations arise not only from physical resemblance, but also from objects’ affordances (function).

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