Deficits and Recovery of First-Order and Second-Order Motion Perception in Patients with Unilateral Posterior Parietal Lesions

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 22-22 ◽  
Author(s):  
D Braun ◽  
M Fahle ◽  
P Schönle ◽  
J Zanker
Keyword(s):  
Motion Perception ◽  
Time Course ◽  
Random Noise ◽  
Second Order ◽  
The Other ◽  
Rectangular Region ◽  
First Order ◽  
Posterior Parietal ◽  
Short Time ◽  
Visual Hemifields

Our aim was to test whether unilateral posterior parietal lesions degrade first-order and second-order motion differentially, and to investigate the time course of any potential recovery. We tested ten patients with circumscribed parietal lesions. Thresholds were measured for the discrimination of the direction of motion of stimuli presented 5.5° peripherally in the ipsilesional and contralesional visual hemifields. Subjects had to indicate whether a rectangular region (1.6 deg × 3 deg) embedded in dynamic random noise background moved up or down. The region contained moving (signal) and flickering (background) dots and moved for 1 s at 2.36 deg s−1. Signal dots were either (a) coherently moving in the same direction as the region (first-order), (b) stationary (second-order), or (c) coherently moving in the opposite direction (theta). Thresholds were defined as percentage of signal dots within the region yielding 75% correct responses. All patients had higher thresholds for second-order than for first-order motion. When contralesional and ipsilesional thresholds were compared, three patients showed proportional threshold elevations for all three types of motion stimuli in the contralesional hemifield. Two of these three patients were tested again five months later. Both showed considerable recovery: in one patient, the contralesional deficit was no longer present; in the other, it was reduced by about half. None of our patients had lesions affecting first-order or second-order motion differentially; lesions always affected first-order and second-order motion similarly. Owing to recovery, these deficits might be detectable only for a short time.

Neural computation of motion in the fly visual system: quadratic nonlinearity of responses induced by picrotoxin in the HS and CH cells

1995 ◽  
Vol 74 (6) ◽  
pp. 2665-2684 ◽  
Author(s):  
Y. Kondoh ◽  
Y. Hasegawa ◽  
J. Okuma ◽  
F. Takahashi
Keyword(s):  
Mean Square Error ◽  
Order Term ◽  
Mirror Image ◽  
Second Order ◽  
The Other ◽  
Linear Component ◽  
Mean Square ◽  
Nonlinear Component ◽  
First Order ◽  
Order Kernel

1. A computational model accounting for motion detection in the fly was examined by comparing responses in motion-sensitive horizontal system (HS) and centrifugal horizontal (CH) cells in the fly's lobula plate with a computer simulation implemented on a motion detector of the correlation type, the Reichardt detector. First-order (linear) and second-order (quadratic nonlinear) Wiener kernels from intracellularly recorded responses to moving patterns were computed by cross correlating with the time-dependent position of the stimulus, and were used to characterize response to motion in those cells. 2. When the fly was stimulated with moving vertical stripes with a spatial wavelength of 5-40 degrees, the HS and CH cells showed basically a biphasic first-order kernel, having an initial depolarization that was followed by hyperpolarization. The linear model matched well with the actual response, with a mean square error of 27% at best, indicating that the linear component comprises a major part of responses in these cells. The second-order nonlinearity was insignificant. When stimulated at a spatial wavelength of 2.5 degrees, the first-order kernel showed a significant decrease in amplitude, and was initially hyperpolarized; the second-order kernel was, on the other hand, well defined, having two hyperpolarizing valleys on the diagonal with two off-diagonal peaks. 3. The blockage of inhibitory interactions in the visual system by application of 10-4 M picrotoxin, however, evoked a nonlinear response that could be decomposed into the sum of the first-order (linear) and second-order (quadratic nonlinear) terms with a mean square error of 30-50%. The first-order term, comprising 10-20% of the picrotoxin-evoked response, is characterized by a differentiating first-order kernel. It thus codes the velocity of motion. The second-order term, comprising 30-40% of the response, is defined by a second-order kernel with two depolarizing peaks on the diagonal and two off-diagonal hyperpolarizing valleys, suggesting that the nonlinear component represents the power of motion. 4. Responses in the Reichardt detector, consisting of two mirror-image subunits with spatiotemporal low-pass filters followed by a multiplication stage, were computer simulated and then analyzed by the Wiener kernel method. The simulated responses were linearly related to the pattern velocity (with a mean square error of 13% for the linear model) and matched well with the observed responses in the HS and CH cells. After the multiplication stage, the linear component comprised 15-25% and the quadratic nonlinear component comprised 60-70% of the simulated response, which was similar to the picrotoxin-induced response in the HS cells. The quadratic nonlinear components were balanced between the right and left sides, and could be eliminated completely by their contralateral counterpart via a subtraction process. On the other hand, the linear component on one side was the mirror image of that on the other side, as expected from the kernel configurations. 5. These results suggest that responses to motion in the HS and CH cells depend on the multiplication process in which both the velocity and power components of motion are computed, and that a putative subtraction process selectively eliminates the nonlinear components but amplifies the linear component. The nonlinear component is directionally insensitive because of its quadratic non-linearity. Therefore the subtraction process allows the subsequent cells integrating motion (such as the HS cells) to tune the direction of motion more sharply.

Extreme Response Predictions for Jack-Up Units in Second Order Stochastic Waves by FORM

2007 ◽  
Author(s):  
Jo̸rgen Juncher Jensen
Keyword(s):  
Second Order ◽  
Sea State ◽  
First Order ◽  
Reliability Method ◽  
Extreme Response ◽  
Stochastic Waves ◽  
Short Time ◽  
Wave Induced ◽  
Jack Up ◽  
Operational Time

The aim of the present paper is to advocate for a very effective stochastic procedure, based on the First Order Reliability Method (FORM), for extreme value predictions related to wave induced loads. All kinds of non-linearities can be included, as the procedure makes use of short time-domain simulations of the response in question. The procedure will be illustrated with a jack-up rig where second order stochastic waves are included in the analysis. The result is the probability of overturning as function of sea state and operational time.

scholarly journals A Survey of Conceptualizations of Politeness

2015 ◽  
Vol 5 (6) ◽  
pp. 115
Author(s):  
Lei Qiu
Keyword(s):  
Second Order ◽  
The Other ◽  
Theoretical Construct ◽  
First Order ◽  
Relational Work ◽  
Other Hand ◽  
Uniform Definition

<p>Along with the general trends of research from traditional Gricean approach to postmodern approach, politeness has been conceptualized as facework, social indexing concept, relational work and interactional work. Based on examination of debates over East group-oriented and Western individual-oriented politeness, first-order and second-order politeness, as well as the universality and relativity of conceptualizations, this paper has roughly demonstrated that the tension between universality and relativity of politeness can help to explain the reason for lack of uniform definition and concept in this field. It is essential for researchers to seek a universal second-order culture-general theoretical construct on one hand, and to look at first-order culture-specific constructs on the other hand.</p>

Thermodynamics of Aluminum Deoxidization Equilibria in GCr18Mo Bearing-Steel

2018 ◽  
Vol 382 ◽  
pp. 80-85 ◽  
Author(s):  
Xin Su ◽  
Shu Qiang Guo ◽  
Meng Ran Qiao ◽  
Hong Yan Zheng ◽  
Li Bin Qin
Keyword(s):  
Bearing Steel ◽  
Second Order ◽  
The Other ◽  
Interaction Parameters ◽  
Interaction Coefficients ◽  
Concentration Region ◽  
Order Interaction ◽  
First Order ◽  
The Relationship ◽  
Reaction Equilibrium

Based on the predecessors of thermodynamic data, the relationship between aluminum contents and oxygen contents of the aluminum deoxidization reaction was calculated. And the influence of activity coefficient to the reaction equilibrium in bearing-steel is analyzed. First-order and second-order interaction coefficients were used to calculate and draw the equilibrium curves, respectively. The effects of different temperature and different interaction parameters on the deoxidization equilibrium curves were studied. And through the curve the influence of the change of aluminum contents to the activity can be known. The trend of the curve with first-order interaction parameters is consistent with the curve with first-order and second-order interaction parameters at the low Al concentration region. And the oxygen contents of curve with first-order interaction parameters are higher than the other curve at the high Al concentration region

An Energy Method for Certain Second-Order Effects With Application to Torsion of Elastic Bars Under Tension

1980 ◽  
Vol 47 (1) ◽  
pp. 75-81 ◽  
Author(s):  
R. T. Shield
Keyword(s):  
Axial Force ◽  
Strain Energy Function ◽  
Incompressible Material ◽  
Elastic Cylinder ◽  
Second Order ◽  
The Other ◽  
Circular Cylinders ◽  
Order Effects ◽  
First Order ◽  
Wide Range

When a mechanical system has a potential energy, it is a simple matter to show that if the generalized force corresponding to a coordinate p is known to first order in p for a range of the other coordinates of the system, then the other generalized forces can be found immediately to second order in p, without requiring a second-order analysis of the system. By this method the second-order change in the axial force when a finitely extended elastic cylinder is twisted is found from the first-order value of the twisting moment. Numerical results for a realistic form of the strain-energy function for an incompressible material suggest that the second-order expression for the axial force is very accurate for a wide range of twist for circular cylinders of rubber-like materials extended 100 percent or more.

A second order version of S2i and U21

1991 ◽  
Vol 56 (3) ◽  
pp. 1038-1063 ◽  
Author(s):  
Gaisi Takeuti
Keyword(s):  
Second Order ◽  
The Other ◽  
Polynomial Hierarchy ◽  
Bounded Arithmetic ◽  
Conservative Extension ◽  
First Order ◽  
Second Order Systems ◽  
Separation Problems

In [1] S. Buss introduced systems of bounded arithmetic , , , (i = 1, 2, 3, …). and are first order systems and and are second order systems. and are closely related to and respectively in the polynomial hierarchy, and and are closely related to PSPACE and EXPTIME respectively. One of the most important problems in bounded arithmetic is whether the hierarchy of bounded arithmetic collapses, i.e. whether = or = for some i, or whether = , or whether is a conservative extension of S2 = ⋃i. These problems are relevant to the problems whether the polynomial hierarchy PH collapses or whether PSPACE = PH or whether PSPACE = EXPTIME. It was shown in [4] that = implies and consequently the collapse of the polynomial hierarchy. We believe that the separation problems of bounded arithmetic and the separation problems of computational complexities are essentially the same problem, and the solution of one of them will lead to the solution of the other.

Inception of the cupule of Quercus macrocarpa and Fagus grandifolia

1979 ◽  
Vol 57 (17) ◽  
pp. 1777-1782 ◽  
Author(s):  
Alastair D. Macdonald
Keyword(s):  
Female Flower ◽  
Fagus Grandifolia ◽  
Second Order ◽  
The Other ◽  
Third Order ◽  
Quercus Macrocarpa ◽  
First Order ◽  
Female Inflorescence ◽  
Inflorescence Axis ◽  
Morphological Nature

The female inflorescence of Fagus grandifolia comprises two flowers; one flower terminates the first-order inflorescence axis, the other flower terminates the second-order inflorescence axis. Each flower is flanked by two cupular valves each of which arise in the axil of a bract. The two valves flanking the flower terminating the first-order inflorescence axis represent second-order inflorescence axes and the two valves flanking the flower terminating the second-order inflorescence axis represent third-order inflorescence axes. The four valves remain discrete. Each female flower of Quercus macrocarpa terminates a second-order inflorescence axis and is surrounded by a continuous cupule. The cupule first forms as two primordia in the axils of each of the two transversal second-order bracts. These cupular primordia represent third-order inflorescence branches. The cupule primordia become continuous about the pedicel by meristem extension. The cupules of Fagus and Quercus are homologous to the extent that they are modified axes of the inflorescence. This serves as a model to interpret the morphological nature of the fagaceous cupule.

scholarly journals Prefrontal Cortex Activation Reflects Efficient Exploitation of Higher-order Statistical Structure

2016 ◽  
Vol 28 (12) ◽  
pp. 1909-1922 ◽  
Author(s):  
Christiane Ahlheim ◽  
Anne-Marike Schiffer ◽  
Ricarda I. Schubotz
Keyword(s):  
Action Observation ◽  
Second Order ◽  
Order Structure ◽  
Order Information ◽  
First Order ◽  
Action Observation Network ◽  
Observation Network ◽  
Statistical Regularities ◽  
Posterior Parietal ◽  
Action Step

Because everyday actions are statistically structured, knowing which action a person has just completed allows predicting the most likely next action step. Taking even more than the preceding action into account improves this predictability but also causes higher processing costs. Using fMRI, we investigated whether observers exploit second-order statistical regularities preferentially if information on possible upcoming actions provided by first-order regularities is insufficient. We hypothesized that anterior pFC balances whether or not second-order information should be exploited. Participants watched videos of actions that were structured by first- and second-order conditional probabilities. Information provided by the first and by the second order was manipulated independently. BOLD activity in the action observation network was more attenuated the more information on upcoming actions was provided by first-order structure, reflecting expectation suppression for more predictable actions. Activation in posterior parietal sites decreased further with second-order information but increased in temporal areas. As expected, second-order information was integrated more when less first-order information was provided, and this interaction was mediated by anterior pFC (BA 10). Observers spontaneously used both the present and the preceding action to predict the upcoming action, and integration of the preceding action was enhanced when the present action was uninformative.

Neural model of first-order and second-order motion perception and magnocellular dynamics

1999 ◽  
Vol 16 (5) ◽  
pp. 953 ◽  
Author(s):  
Aijaz A. Baloch ◽  
Stephen Grossberg ◽  
Ennio Mingolla ◽  
C. A. M. Nogueira
Keyword(s):  
Motion Perception ◽  
Neural Model ◽  
Second Order ◽  
First Order

Processing of first-order motion in marmoset visual cortex is influenced by second-order motion

2006 ◽  
Vol 23 (5) ◽  
pp. 815-824 ◽  
Author(s):  
NICK BARRACLOUGH ◽  
CHRIS TINSLEY ◽  
BEN WEBB ◽  
CHRIS VINCENT ◽  
ANDREW DERRINGTON
Keyword(s):  
Visual Cortex ◽  
Low Frequency ◽  
Second Order ◽  
The Other ◽  
Motion Processing ◽  
Single Neurons ◽  
First Order ◽  
The Third ◽  
Early Visual Cortex ◽  
Direction Sensitivity

We measured the responses of single neurons in marmoset visual cortex (V1, V2, and the third visual complex) to moving first-order stimuli and to combined first- and second-order stimuli in order to determine whether first-order motion processing was influenced by second-order motion. Beat stimuli were made by summing two gratings of similar spatial frequency, one of which was static and the other was moving. The beat is the product of a moving sinusoidal carrier (first-order motion) and a moving low-frequency contrast envelope (second-order motion). We compared responses to moving first-order gratings alone with responses to beat patterns with first-order and second-order motion in the same direction as each other, or in opposite directions to each other in order to distinguish first-order and second-order direction-selective responses. In the majority (72%, 67/93) of cells (V1 73%, 45/62; V2 70%, 16/23; third visual complex 75%, 6/8), responses to first-order motion were significantly influenced by the addition of a second-order signal. The second-order envelope was more influential when moving in the opposite direction to the first-order stimulus, reducing first-order direction sensitivity in V1, V2, and the third visual complex. We interpret these results as showing that first-order motion processing through early visual cortex is not separate from second-order motion processing; suggesting that both motion signals are processed by the same system.

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