scholarly journals Recovery of fMRI Activation in Motion Area MT Following Storage of the Motion Aftereffect

1999 ◽  
Vol 81 (1) ◽  
pp. 388-393 ◽  
Author(s):  
Jody C. Culham ◽  
Sean P. Dukelow ◽  
Tutis Vilis ◽  
Frank A. Hassard ◽  
Joseph S. Gati ◽  
...  
Keyword(s):  
Storage Period ◽  
Motion Aftereffect ◽  
Illusory Motion ◽  
Continuous Motion ◽  
Area Mt ◽  
Perceptual Effect ◽  
Static Test ◽  
Physical Motion ◽  
Stationary Test ◽  
The Relationship

Culham, Jody C., Sean P. Dukelow, Tutis Vilis, Frank A. Hassard, Joseph S. Gati, Ravi S. Menon, and Melvyn A. Goodale. Recovery of fMRI activation in motion area MT following storage of the motion aftereffect. J. Neurophysiol. 81: 388–393, 1999. We used functional magnetic resonance imaging (fMRI) during storage of the motion aftereffect (MAE) to examine the relationship between motion perception and neural activity in the human cortical motion complex MT+ (including area MT and adjacent motion-selective cortex). MT+ responds not only to physical motion but also to illusory motion, as in the MAE when subjects who have adapted to continuous motion report that a subsequent stationary test stimulus appears to move in the opposite direction. In the phenomenon of storage, the total decay time of the MAE is extended by inserting a dark period between adaptation and test phases. That is, when the static test pattern is presented after a storage period equal in duration to the normal MAE, the illusory motion reappears for almost as long as the original effect despite the delay. We examined fMRI activation in MT+ during and after storage. Seven subjects viewed continuous motion, followed either by an undelayed stationary test (immediate MAE) or by a completely dark storage interval preceding the test (stored MAE). Like the perceptual effect, activity in MT+ dropped during the storage interval then rebounded to reach a level much higher than after the same delay without storage. Although MT+ activity was slightly enhanced during the storage period following adaptation to continuous motion (compared with a control sequence in which the adaptation grating oscillated and no MAE was perceived), this enhancement was much less than that observed during the perceptual phenomenon. These results indicate that following adaptation, activity in MT+ is pronounced only with the presentation of an appropriate visual stimulus, during which the MAE is perceived.

Spatial Induction of Illusory Motion

Perception ◽  
1982 ◽  
Vol 11 (2) ◽  
pp. 187-199 ◽  
Author(s):  
Walter C Gogel ◽  
Bernard W Griffin
Keyword(s):  
Apparent Motion ◽  
Alternative Interpretation ◽  
Test Point ◽  
Illusory Motion ◽  
Frontoparallel Plane ◽  
Continuous Motion ◽  
Motion In Depth ◽  
Physical Motion ◽  
Induced Motion

Induced motion is not limited to continuous motions presented on a frontoparallel plane. Experiments were conducted to investigate several varieties of induced motion to which theories of induced motion must apply. The observer indicated the perceived path of motion of a vertically moving test point to which induced motion at right angles to the physical motion was added by the motion of two inducing points. In experiment 1 all motions (both apparently and physically) were in a frontoparallel plane. It was found that discrete displacement as well as continuous motion of the test and inducing points produced substantial amounts of induction. In experiment 2 the inducing points were continuously moved in stereoscopic distance rather than remaining in an apparent frontoparallel plane. A large amount of apparent motion in depth was found in the vertically moving test point and was interpreted as an induced motion in depth. In experiment 3 an alternative interpretation of the phenomenon of experiment 2, in terms of an apparent vergence for the two images of the test point, was investigated and found to be unlikely. In experiment 4, with all the points moving continuously in a frontoparallel plane, eye motions as well as induced motions were measured, with the observer fixating either the test point or an inducing point. Substantial amounts of induction were obtained under both conditions of fixation. The consequences of these findings for theories of induced motion are discussed.

The Motion Analogue of the Café Wall Illusion

Perception ◽  
1997 ◽  
Vol 26 (5) ◽  
pp. 569-584 ◽  
Author(s):  
Tatsuto Takeuchi
Keyword(s):  
Motion Perception ◽  
Time Domain ◽  
Visual Motion ◽  
Motion Aftereffect ◽  
Illusory Motion ◽  
Space Domain ◽  
Static Test ◽  
First Order ◽  
Motion System ◽  
Motion Energy

Detecting visual motion is computationally equivalent to detecting spatiotemporally oriented contours. The question addressed in this study is whether the illusory oriented contour in the space–space domain induces corresponding illusory motion perception. Two experiments were conducted. In experiment 1, the Café Wall pattern, which elicits a strong illusion of orientation (Café Wall illusion), was found to induce an illusion of motion when this pattern was converted to the space – time domain. The strength of the motion illusion depends on the mortar luminance and width, as for the Café Wall illusion. In experiment 2, the adaptation to this illusion of motion was found to induce a motion aftereffect in a static test, which indicates that a first-order-motion system contributes to the induction of the motion illusion. In fact, the motion-energy model was able to predict the strength of this motion aftereffect.

scholarly journals Motion Induced Colours Fusion

2019 ◽  
Author(s):  
Ahmad Yousef
Keyword(s):  
Opposite Direction ◽  
Illusory Motion ◽  
Physical Motion ◽  
Optimal Fusion ◽  
Motion Reversal

This article provides evidence that motion has the ability to stably fuse two different colored ‘spatially separated’ stimuli without impairments against the shape of those separated stimuli. Based on our observations, dilated pupils promote colours fusion; and the optimal fusion happens when the stimuli are moving in opposite direction of the actual physical motion, namely, when there is illusory motion reversal. The previous observations suggested that retinal peripheries have main contributions on the present illusion which we called; motion induced colours fusion ‘MICF’ illusion.

scholarly journals Feature attention for binocular disparity in primate area MT depends on tuning strength

2015 ◽  
Vol 113 (5) ◽  
pp. 1545-1555 ◽  
Author(s):  
Douglas A. Ruff ◽  
Richard T. Born
Keyword(s):  
Binocular Disparity ◽  
Receptive Fields ◽  
Sensory Information ◽  
Neuronal Population ◽  
Area Mt ◽  
Temporal Area ◽  
Mt Neurons ◽  
Feature Attention ◽  
The Difference ◽  
The Relationship

Attending to a stimulus modulates the responses of sensory neurons that represent features of that stimulus, a phenomenon named “feature attention.” For example, attending to a stimulus containing upward motion enhances the responses of upward-preferring direction-selective neurons in the middle temporal area (MT) and suppresses the responses of downward-preferring neurons, even when the attended stimulus is outside of the spatial receptive fields of the recorded neurons (Treue S, Martinez-Trujillo JC. Nature 399: 575–579, 1999). This modulation renders the representation of sensory information across a neuronal population more selective for the features present in the attended stimulus (Martinez-Trujillo JC, Treue S. Curr Biol 14: 744–751, 2004). We hypothesized that if feature attention modulates neurons according to their tuning preferences, it should also be sensitive to their tuning strength, which is the magnitude of the difference in responses to preferred and null stimuli. We measured how the effects of feature attention on MT neurons in rhesus monkeys ( Macaca mulatta) depended on the relationship between features—in our case, direction of motion and binocular disparity—of the attended stimulus and a neuron's tuning for those features. We found that, as for direction, attention to stimuli containing binocular disparity cues modulated the responses of MT neurons and that the magnitude of the modulation depended on both a neuron's tuning preferences and its tuning strength. Our results suggest that modulation by feature attention may depend not just on which features a neuron represents but also on how well the neuron represents those features.

Topography of evoked potentials associated with illusory motion perception as a motion aftereffect

2002 ◽  
Vol 13 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Yuji Kobayashi ◽  
Aihide Yoshino ◽  
Tsuneyuki Ogasawara ◽  
Soichiro Nomura
Keyword(s):  
Evoked Potentials ◽  
Motion Perception ◽  
Motion Aftereffect ◽  
Illusory Motion

Mechanical Properties of Bulk Nanocrystalline Silver-Using Compression Tests

2010 ◽  
Vol 152-153 ◽  
pp. 1313-1316
Author(s):  
Guo Jun Hu ◽  
Zhi Quan Hong
Keyword(s):  
Mechanical Properties ◽  
Coarse Grained ◽  
Strain Rates ◽  
Test Results ◽  
Compression Tests ◽  
Static Test ◽  
Rate Dependent ◽  
Average Grain Size ◽  
Bulk Nanocrystalline ◽  
The Relationship

In this paper, the compression test on the bulk nanocrystalline sliver ( n Ag) with average grain size of 50 nm was made. The stress-strain curves under different strain rates were obtained by test. The test results show that the mechanical behavior of n Ag is rate-dependent, and the dynamic compress yield stress are about 1.5 times of that n Ag in static test condition; The effect of strain harding on n Ag is smaller than that of coarse-grained silver (c Ag) in plastic deformation; The relationship between the yield strength and the logarithm of strain rate is approximately linear.

scholarly journals Type of Featural Attention Differentially Modulates hMT+ Responses to Illusory Motion Aftereffects

2009 ◽  
Vol 102 (5) ◽  
pp. 3016-3025 ◽  
Author(s):  
Miguel Castelo-Branco ◽  
Lajos R. Kozak ◽  
Elia Formisano ◽  
João Teixeira ◽  
João Xavier ◽  
...  
Keyword(s):  
Selective Attention ◽  
Motion Aftereffect ◽  
Human Motion ◽  
Real Surface ◽  
Illusory Motion ◽  
Real Motion ◽  
Motion Signal ◽  
Color Features ◽  
Motion Aftereffects ◽  
Global Activity

Activity in the human motion complex (hMT+/V5) is related to the perception of motion, be it either real surface motion or an illusion of motion such as apparent motion (AM) or motion aftereffect (MAE). It is a long-lasting debate whether illusory motion-related activations in hMT+ represent the motion itself or attention to it. We have asked whether hMT+ responses to MAEs are present when shifts in arousal are suppressed and attention is focused on concurrent motion versus nonmotion features. Significant enhancement of hMT+ activity was observed during MAEs when attention was focused either on concurrent spatial angle or color features. This observation was confirmed by direct comparison of adapting (MAE inducing) versus nonadapting conditions. In contrast, this effect was diminished when subjects had to report on concomitant speed changes of superimposed AM. The same finding was observed for concomitant orthogonal real motion (RM), suggesting that selective attention to concurrent illusory or real motion was interfering with the saliency of MAE signals in hMT+. We conclude that MAE-related changes in the global activity of hMT+ are present provided selective attention is not focused on an interfering feature such as concurrent motion. Accordingly, there is a genuine MAE-related motion signal in hMT+ that is neither explained by shifts in arousal nor by selective attention.

scholarly journals Chlorophyll as an indicator of green tea quality

2014 ◽  
Vol 83 (10) ◽  
pp. S103-S109 ◽  
Author(s):  
Martina Ošťádalová ◽  
Bohuslava Tremlová ◽  
Jana Pokorná ◽  
Martin Král
Keyword(s):  
Chlorophyll Content ◽  
Green Tea ◽  
Storage Time ◽  
Chlorophyll Concentration ◽  
Storage Period ◽  
Storage Conditions ◽  
Qualitative Variable ◽  
Chlorophyll Contents ◽  
Tea Quality ◽  
The Relationship

The objective of this work was to study the changes in chlorophyll contents in green teas stored under different conditions and to suggest the most suitable way and length of green tea storage. A secondary aim was to evaluate the possibility of using the chlorophyll content as an indicator of tea freshness. Samples for analysis were obtained from a range of tea-growing regions. Chlorophyll contents were measured using UV-vis spectrophotometry. Chlorophyll absorbance was measured at 642.5 and 660 nm. Prior to storage, chlorophyll concentration in teas ranged from 1.12 to 1.89 mg per 1 g of tea, which corresponded to data given by other authors. Storage was found to lead to a decline in chlorophyll concentration. From the 6th month of storage onwards, a significant decrease (P < 0.05) was observed in all samples, irrespective of storage conditions. Based on the findings of this study, original and metal packaging can be considered the most chlorophyll-friendly. On the other hand, glass and paper packaging stored in direct daylight were found to have the strongest impact on chlorophyll concentration. Overall, it can be concluded that the storage time can have a strong influence on oolong green tea colour as an important qualitative variable. Thus, the shelf-life of tea should be shorter than the 12 months claimed by most manufacturers. Once the relationship between changes in chlorophyll concentration and length of the storage period had been established, the chlorophyll content was suggested as an indicator of the storage time (freshness) of a tea substance.

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