Computing with Self-Excitatory Cliques: A Model and an Application to Hyperacuity-Scale Computation in Visual Cortex

1999 ◽  
Vol 11 (1) ◽  
pp. 21-66 ◽  
Author(s):  
Douglas A. Miller ◽  
Steven W. Zucker
Keyword(s):  
Visual Processing ◽  
Network Architecture ◽  
Early Stage ◽  
Cortical Cell ◽  
Pyramidal Cells ◽  
Direct Calculation ◽  
Formal Theory ◽  
Cortical Cells ◽  
Cell Counts ◽  
Spatiotemporal Response

We present a model of visual computation based on tightly inter-connected cliques of pyramidal cells. It leads to a formal theory of cell assemblies, a specific relationship between correlated firing patterns and abstract functionality, and a direct calculation relating estimates of cortical cell counts to orientation hyperacuity. Our network architecture is unique in that (1) it supports a mode of computation that is both reliable and efficent; (2) the current-spike relations are modeled as an analog dynamical system in which the requisite computations can take place on the time scale required for an early stage of visual processing; and (3) the dynamics are triggered by the spatiotemporal response of cortical cells. This final point could explain why moving stimuli improve vernier sensitivity.

Cytochalasin B: effects on root morphogenesis in Allium cepa

1973 ◽  
Vol 51 (12) ◽  
pp. 2269-2273 ◽  
Author(s):  
D. des S. Thomas ◽  
N. M. Lager ◽  
E. K. Manavathu
Keyword(s):  
Allium Cepa ◽  
Root Length ◽  
Cytochalasin B ◽  
Morphological Changes ◽  
Cortical Cell ◽  
Root Tip ◽  
Metabolic Inhibitor ◽  
High Concentration ◽  
Cortical Cells ◽  
Cell Counts

Cytochalasin B (CB) applied at 30 μg/ml to seeds of onion, Allium cepa, from the start of imbibition, produced a reversible inhibition of mitosis and axis elongation. Inhibition appeared only after the 4th day and increased progressively thereafter. Mitotic inhibition by a 24-h pulse of CB applied to 6-day-old seedlings increased with root length. These results suggest that CB affects plant mitosis indirectly, possibly via inhibition of transport. CB did not produce polyploid or multinucleate cells.Cytochalasin B (30 μg/ml) supplied for 3 days to roots of onion bulbs, growing in water, produced morphological changes which are expressed here as percentages of the controls. Root length decreased (44%) while diameter increased (148%). Cortical cell lengths decreased (53%) and diameters increased (128%) when measured at 9 mm from the root tip. These compensatory changes resulted in comparatively minor decreases in root (97%) and cell (90%) volume, indicating that CB, even at the high concentration used, was not acting primarily as a general metabolic inhibitor. Cell counts along diameters at comparable distances, 130 cortical cells from the apical initial region, showed no change in the number of cells representing cortex and stele.

The “Mosaic Stage” in Amodal Completion as Characterized by Magnetoencephalography Responses

2006 ◽  
Vol 18 (8) ◽  
pp. 1394-1405 ◽  
Author(s):  
Gijs Plomp ◽  
Lichan Liu ◽  
Cees van Leeuwen ◽  
Andreas A. Ioannides
Keyword(s):  
Neural Activity ◽  
Visual Processing ◽  
Early Stage ◽  
Amodal Completion ◽  
Peak Latency ◽  
Per Se

We investigated the process of amodal completion in a same-different experiment in which test pairs were preceded by sequences of two figures. The first of these could be congruent to a global or local completion of an occluded part in the second figure, or a mosaic interpretation of it. We recorded and analyzed the magnetoencephalogram for the second figures. Compared to control conditions, in which unrelated primes were shown, occlusion and mosaic primes reduced the peak latency and amplitude of neural activity evoked by the occlusion patterns. Compared to occlusion primes, mosaic ones reduced the latency but increased the amplitude of evoked neural activity. Processes relating to a mosaic interpretation of the occlusion pattern, therefore, can dominate in an early stage of visual processing. The results did not provide evidence for the presence of a functional “mosaic stage” in completion per se, but characterize the mosaic interpretation as a qualitatively special one that can rapidly emerge in visual processing when context favors it.

CORTICAL CELL COUNTS IN SENILE DEMENTIA

1977 ◽  
Vol 36 (3) ◽  
pp. 633 ◽  
Author(s):  
Robert D. Terry ◽  
Carol Fitzgerald ◽  
Arthur Peck ◽  
Judith Millner ◽  
Peter Farmer
Keyword(s):  
Senile Dementia ◽  
Cortical Cell ◽  
Cell Counts

Early Periderm Ontogeny in Fraxinuspennsylvanica, Ailanthusaltissima, Robiniapseudoacacia, and Pinusresinosa, Seedlings

1972 ◽  
Vol 2 (2) ◽  
pp. 135-143 ◽  
Author(s):  
G. A. Borger ◽  
T. T. Kozlowski
Keyword(s):  
Cell Layer ◽  
Cortical Cell ◽  
Cortical Cells ◽  
Mother Cells

The subepidermal cell layer was the site of origin of the first periderm in the hypocotyl and internodes of Fraxinuspennsylvanica and Ailanthusaltissima. In the hypocotyl of Robiniapsendoacacia, the first periderm arose in cortical cells near the phloem; in the internodes it originated in the subepidermal, second, or third cortical cell layer. The outermost cell layer of the pericycle gave rise to the first periderm in the hypocotyl of Pinusresinosa. In all four species, periderm appeared first near the base of the hypocotyl and developed acropetally. In A. altissima and R. pseudoaeacia, phellem mother cells were cut off by the phellogen. These subsequently divided to produce phellem cells. In F. pennsylvanica and P. resinosa, phellem cells were produced directly from the phellogen.

scholarly journals Visual attention spreads broadly but selects information locally

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Satoshi Shioiri ◽  
Hajime Honjyo ◽  
Yoshiyuki Kashiwase ◽  
Kazumichi Matsumiya ◽  
Ichiro Kuriki
Keyword(s):  
Visual Attention ◽  
Spatial Attention ◽  
Visual Processing ◽  
Early Stage ◽  
Event Related Potential ◽  
Spatial Spread ◽  
Local Selection ◽  
Unified View ◽  
Behavioral Evidence ◽  
P3 Component

Abstract Visual attention spreads over a range around the focus as the spotlight metaphor describes. Spatial spread of attentional enhancement and local selection/inhibition are crucial factors determining the profile of the spatial attention. Enhancement and ignorance/suppression are opposite effects of attention, and appeared to be mutually exclusive. Yet, no unified view of the factors has been provided despite their necessity for understanding the functions of spatial attention. This report provides electroencephalographic and behavioral evidence for the attentional spread at an early stage and selection/inhibition at a later stage of visual processing. Steady state visual evoked potential showed broad spatial tuning whereas the P3 component of the event related potential showed local selection or inhibition of the adjacent areas. Based on these results, we propose a two-stage model of spatial attention with broad spread at an early stage and local selection at a later stage.

scholarly journals Bacterial Meningitis in the Absence of Cerebrospinal Fluid Pleocytosis: A Case Report and Review of the Literature

2014 ◽  
Vol 25 (5) ◽  
pp. 249-251 ◽  
Author(s):  
Ryota Hase ◽  
Naoto Hosokawa ◽  
Makito Yaegashi ◽  
Kiyoharu Muranaka
Keyword(s):  
Cerebrospinal Fluid ◽  
Bacterial Meningitis ◽  
Lumbar Puncture ◽  
Early Stage ◽  
Review Of The Literature ◽  
Csf Analysis ◽  
Cell Counts ◽  
Csf Pleocytosis ◽  
Cerebrospinal Fluid Pleocytosis ◽  
Rule Out

Elevation of cerebrospinal fluid (CSF) cell count is a key sign in the diagnosis of bacterial meningitis. However, there have been reports of bacterial meningitis with no abnormalities in initial CSF testing. This type of presentation is extremely rare in adult patients. Here, a case involving an 83-year-old woman who was later diagnosed with bacterial meningitis caused byNeisseria meningitidisis described, in whom CSF at initial and second lumbar puncture did not show elevation of cell counts. Twenty-six non-neutropenic adult cases of bacterial meningitis in the absence of CSF pleocytosis were reviewed. The frequent causative organisms wereStreptococcus pneumoniaeandN meningitidis. Nineteen cases had bacteremia and seven died. The authors conclude that normal CSF at lumbar puncture at an early stage cannot rule out bacterial meningitis. Therefore, repeat CSF analysis should be considered, and antimicrobial therapy must be started immediately if there are any signs of sepsis or meningitis.

A Visual Channel Theory Approach to Pilot Performance and Simulator Imagery

1981 ◽  
Vol 25 (1) ◽  
pp. 223-227
Author(s):  
David Regan ◽  
Ronald Kruk ◽  
Ken Beverley ◽  
Tom Longridge
Keyword(s):  
Visual Processing ◽  
Early Stage ◽  
Visual Display ◽  
Flight Simulator ◽  
Theory Approach ◽  
Pilot Performance ◽  
Visual Channel ◽  
Display Design ◽  
Preliminary Study ◽  
Channel Theory

There is a body of experimental evidence supporting the hypothesis that an early stage of visual processing consists of analyzing retinal image information into a number of abstract categories or features, called channels. This paper briefly reviews the channel hypothesis and cites potential implications for flight simulator visual display design. The results of a preliminary study designed to investigate the relationships between channel sensitivity and flight simulator landing performance are presented.

NHE3 activity and trafficking depend on the state of actin organization in proximal tubule

2001 ◽  
Vol 280 (2) ◽  
pp. F283-F290 ◽  
Author(s):  
C. Chalumeau ◽  
D. Du Cheyron ◽  
N. Defontaine ◽  
O. Kellermann ◽  
M. Paillard ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Cortical Cell ◽  
Membrane Vesicles ◽  
Cytochalasin D ◽  
The State ◽  
Protein Abundance ◽  
Transport Activity ◽  
Cortical Cells ◽  
Actin Organization ◽  
Luminal Membrane

The present study was addressed to define the contribution of cytoskeleton elements in the kidney proximal tubule Na+/H+ exchanger 3 (NHE3) activity under basal conditions. We used luminal membrane vesicles (LMV) isolated from suspensions of rat cortical tubules pretreated with either colchicine (Colch) or cytochalasin D (Cyto D). Colch pretreatment of suspensions (200 μM for 60 min) moderately decreased LMV NHE3 activity. Cyto D pretreatment (1 μM for 60 min) elicited an increase in LMV NHE3 transport activity but did not increase Na-glucose cotransport activity. Cyto D pretreatment of suspensions did not change the apparent affinity of NHE3 for internal H+. In contrast, after Cyto D pretreatment of the suspensions, NHE3 protein abundance was increased in LMV and remained unchanged in cortical cell homogenates. The effect of Cyto D on NHE3 was further assessed with cultures of murine cortical cells. The amount of surface biotinylated NHE3 increased on Cyto D treatment, whereas NHE3 protein abundance was unchanged in cell homogenates. In conclusion, under basal conditions NHE3 activity depends on the state of actin organization possibly involved in trafficking processes between luminal membrane and intracellular compartment.

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