scholarly journals ASYMMETRY IN REGARD TO THE EFFECTS OF MAGNOCELLULAR AND PARVOCELLULAR LESIONS

2021 ◽  
Author(s):  
Bernt Skottun
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Cell Number ◽  
Visual Task ◽  
The Other ◽  
Visual Stream ◽  
Magnocellular System ◽  
Lateral Geniculate ◽  
Parvocellular System ◽  
Visual Tasks ◽  
Number Of Cells

The placing of lesions in the magno- and parvocellular layers of the Lateral Geniculate Nucleus (LGN) of the visual stream has been used in attempts to assess the contributions of the two systems to various visual tasks. However, because there are about ten times as many parvocellular cells as magnocellular cells a lesion blocking the parvocellular input would be expected to have a larger deleterious impact than one blocking the magnocellular input. Thus, a visual task that depends upon all inputs, i.e. which is not linked specifically to either the magno- or parvocellular systems, would be expected to be more severely affected by a lesion in the parvocellular system than by one in the magnocellular system simply on the basis of the number of cells involved. A larger impact of a parvocellular lesion can, therefore, not be taken to mean that the task in question is specifically, or predominantly, linked to this system. Effects following magnocellular lesions (and not observed following parvocellular lesions), on the other hand, cannot be accounted for on the basis of cell number. There is, therefore, an asymmetry, in regard to the significance of the effects of lesions placed in the magno- and parvocellular layers of the LGN.

The Relation between Angle of Display and Performance in a Prolonged Visual Task

1950 ◽  
Vol 2 (4) ◽  
pp. 176-181 ◽  
Author(s):  
D. C. Fraser
Keyword(s):  
Present Experiment ◽  
Visual Task ◽  
The Other ◽  
Vertical Position ◽  
Display Surface ◽  
Visual Tasks ◽  
And Performance

An experiment is described to test the relation between angle of display and performance in prolonged visual tasks, using the Clock Test in three positions of display surface, vertical, at an angle of 45 degrees to the horizontal, and horizontal. In every case the line of regard was kept at right-angles to the display surface. The results indicate that significantly fewer stimuli are missed in the vertical position of the display surface than in the other two. The deterioration observed in the second half-hour of the original Clock Test experiments was not found in the present experiment, and two possible reasons for this are discussed briefly.

The cellular structure of the female reproductive system within the Heteroderinae and Meloidogyninae (Nematoda)

Nematology ◽  
2002 ◽  
Vol 4 (8) ◽  
pp. 953-963 ◽  
Author(s):  
Etienne Geraert ◽  
Rita Van Driessche ◽  
Gerrit Karssen ◽  
Wim Bert
Keyword(s):  
Reproductive System ◽  
Cellular Structure ◽  
Cell Number ◽  
The Other ◽  
Genital System ◽  
Female Reproductive System ◽  
Young Females ◽  
Genital Structure ◽  
Number Of Cells ◽  
Female Genital

AbstractGonads from living young females, representing 23 different species, were extracted to study the cellular structure of the female genital structure within the Meloidogyninae and Heteroderinae. All genera studied can be characterised by their cellular spermatheca morphology. Within Meloidogyne a spherical spermatheca is found with lobe-like protruding cells, most species having 16 to 18 spermatheca cells with interlaced cell boundaries while M. microtyla and M. ichinohei have more spermatheca cells with different cell boundaries. Heterodera and Globodera reveal a comparable gonad structure. The spermatheca cells of Heterodera are columnar and arranged in a restricted number of rows, whereas in Globodera the spermatheca cells are squarish to rounded, depending on the species. The gonad morphology of Afenestrata koreana is clearly different from what would be expected based on the related genera Globodera and Heterodera. The apparently simplest genital system was found in Meloidodera floridensis where the uterus has a limited number of cells. In the other genera studied a large and variable cell number was found.

scholarly journals Scaling the primate lateral geniculate nucleus: Niche and neurodevelopment in the regulation of magnocellular and parvocellular cell number and nucleus volume

2014 ◽  
Vol 522 (8) ◽  
pp. 1839-1857 ◽  
Author(s):  
Barbara L. Finlay ◽  
Christine J. Charvet ◽  
Isle Bastille ◽  
Desmond T. Cheung ◽  
José Augusto P.C. Muniz ◽  
...  
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Cell Number ◽  
Lateral Geniculate ◽  
Nucleus Volume

scholarly journals A new transformation of cone responses to opponent color responses

2021 ◽  
Author(s):  
Ralph W. Pridmore
Keyword(s):  
Comparative Analysis ◽  
Color Vision ◽  
Lateral Geniculate Nucleus ◽  
Literature Search ◽  
The Other ◽  
Response Curves ◽  
Lateral Geniculate ◽  
Opponent Color ◽  
Cardinal Directions ◽  
Unique Hues

AbstractIt is widely agreed that the color vision process moves quickly from cone receptors to opponent color cells in the retina and lateral geniculate nucleus. Many workers have proposed the transformation or coding of long, medium, short (LMS) cone responses to r − g, y − b opponent color chromatic responses (unique hues) on the following basis: That L, M, S cones represent Red, Green, and Blue hues, with Yellow represented by (L + M), while r − g and y − b represent the opponent pairs of unique hues. The traditional coding from cones to opponent colors is that L − M gives r − g, while (L + M) − S gives y − b. This convention is open to several criticisms, and a new coding is required. A literature search produced 16 studies of cone responses LMS and 15 studies of spectral (i.e., ygb) opponent color chromatic responses, in terms of response wavelength peaks. Comparative analysis of the two sets of studies shows the means are almost identical (within 3 nm; i.e., L = y, M = g, S = b). Further, the response curves of LMS are very similar shapes to ygb. In sum, each set can directly transform to the other on this proposed coding: (S + L) − M gives r − g, while L − S gives y − b. This coding activates neural operations in the cardinal directions r − g and y − b.

scholarly journals A Fast, Decentralized, Self-Aligned Carrier Method for Multicellular Converters

2020 ◽  
Vol 11 (1) ◽  
pp. 137
Author(s):  
Quoc Dung Phan ◽  
Guillaume Gateau ◽  
Phu Cong Nguyen ◽  
Marc Cousineau ◽  
Huu Phuc To ◽  
...  
Keyword(s):  
Conventional Method ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Iteration Process ◽  
Cell Number ◽  
Index Number ◽  
Multilevel Converter ◽  
Start Up ◽  
Multiphase Converters ◽  
Number Of Cells

This paper proposes a fast, decentralized method for self-aligning the carriers of a multiphase/multilevel converter operating on the basis of phase-shifted pulse width modulation or level-shifted pulse width modulation. In the proposed method, each cell of the converter synchronizes and updates simultaneously its own carrier angle or carrier level based on the information shared with its neighboring cell, such as its angle/level, its index number, and the total number of activated cells of the converter. Different from the conventional decentralized method (with basic and modified updating rules), which requires some conditions in terms of cell number and initial carrier angles to start up and operate properly, the proposed method can be applied to the system with any number of cells and does not require special conditions of initial carrier angles. Further, while the conventional method needs an iteration process to adjust the inter-carrier phase-shifts and can be applied only to a multiphase converter which uses phase-shifted pulse width modulation, the proposed method offers an accurate and fast alignment of phases (for phase-shifted pulse width modulation) or levels (for level-shifted pulse width modulation) and thus can be applied to both multiphase and multilevel converter types. The simulations and the experimental results are presented in detail to show the validity and the effectiveness of the proposed methods. Further, thorough simulations on multiphase converters with different number of cells also show that the proposed method is much faster than the conventional method in both configuration and reconfiguration processes, especially in case the system has a large number of cells.

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