scholarly journals Behavioral evaluation of visual function of rats using a visual discrimination apparatus

2007 ◽  
Vol 162 (1-2) ◽  
pp. 84-90 ◽  
Author(s):  
Biju B. Thomas ◽  
Deedar M. Samant ◽  
Magdalene J. Seiler ◽  
Robert B. Aramant ◽  
Sharzad Sheikholeslami ◽  
...  
Keyword(s):  
Visual Function ◽  
Visual Discrimination ◽  
Discrimination Apparatus

Visual Discrimination Learning in Rats with Lesions of Superior Colliculus: Door-Push and Approach Errors in Modified Jumping Stand

1981 ◽  
Vol 33 (3b) ◽  
pp. 141-157 ◽  
Author(s):  
Paul Dean ◽  
Sian G. Pope
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Open Field ◽  
Discrimination Learning ◽  
Visual Discrimination ◽  
Visual Discrimination Learning ◽  
Central Platform ◽  
Area Centralis ◽  
Scanning Head ◽  
Discrimination Apparatus

It has been suggested that, for some species, lesions of the superior colliculus affect visual discrimination learning, but only in certain conditions: (a) when problems are first learnt only after operation, or (b) when discriminanda require detailed scanning, or (c) when “approach” responses to the discriminanda are measured, rather than the response of actually touching them. These suggestions were examined in rats learning visual discriminations in a modified jumping-stand apparatus, after sustaining large lesions of the superior colliculus (and in some cases also of the pretectum). The lesions produced open-field hyperactivity and reduced exploration, indicating effective tectal damage, but the rats learnt a series of difficult discriminations in a door-push task as fast as normal rats, and they did not make more approach errors. Their main abnormality in the discrimination apparatus was that they looked less often between the stimulus doors before stepping across to one of them from the central platform. It is suggested that in rats, as in other animals, lesions of the superior colliculus disrupt the control of scanning head and eye movements; in rats, however, such disruption need not affect discrimination learning (at least in some kinds of apparatus), possibly because the retina of the rat has a relatively poorly developed area centralis.

scholarly journals ON THE VARIABILITY OF CRITICAL ILLUMINATION FOR FLICKER FUSION AND INTENSITY DISCRIMINATION

1936 ◽  
Vol 19 (3) ◽  
pp. 503-522 ◽  
Author(s):  
W. J. Crozier
Keyword(s):  
Visual Acuity ◽  
General Problem ◽  
Visual Function ◽  
Visual Discrimination ◽  
Dark Adaptation ◽  
Intensity Discrimination ◽  
The Sun ◽  
Threshold Response ◽  
Independent Variable ◽  
Flicker Fusion

From the data of experiments with bees in which threshold response is employed as a means of recognizing visual discrimination between stripes of equal width alternately illuminated by intensities I1 and I2, it is shown that the detectable increment of intensity ΔI, where ΔI = I2 - I1, is directly proportional to σI2 (I1 being fixed). From tests of visual acuity, where I1 = 0 and the width of the stripes is varied, σI2 = kI2 + const.; here I2 = ΔI, and ΔI/I2 = 1. When the visual excitability of the bee is changed by dark adaptation, λI ≡ kΔI (= k' σΔI) = k'' I + const. For the measurements of critical illumination at threshold response to flicker, σI2 (= σΔI) = k I2 = k' ΔI + const. The data for critical illumination producing threshold response to flicker in the sun-fish Lepomis show for the rods σI2 = K I2 for the cones σI2 = K'(I2 + const.). The data thus indicate that in all these experiments essentially the same visual function is being examined, and that the recognition of the production of a difference in effect by alternately illuminated stripes takes place in such a way that d (ΔI)/d (σI2) = const., and that ΔI is directly proportional to I (or "I2," depending on the nature of the experiment). It is pointed out that the curve for each of the cases considered can be gotten equally well if mean I or σI is plotted as a function of the independent variable involved in the experiment. Certain consequences of these and related facts are important for the treatment of the general problem of intensity discrimination.

X-Ray Microanalysis of Nickel and Cobalt Intensified Peroxidase- Antiperoxidase For Verification of Reaction Sites

1985 ◽  
Vol 43 ◽  
pp. 468-469
Author(s):  
A. Angel ◽  
K. Miller ◽  
V. Seybold ◽  
R. Kriebel
Keyword(s):  
Reaction Mechanisms ◽  
Visual Discrimination ◽  
Osmium Tetroxide ◽  
Ultrastructural Level ◽  
Microscopic Level ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
X Ray ◽  
Insoluble Polymer ◽  
Cytochemical Reaction

Localization of specific substances at the ultrastructural level is dependent on the introduction of chemicals which will complex and impart an electron density at specific reaction sites. Peroxidase-antiperoxidase(PAP) methods have been successfully applied at the electron microscopic level. The PAP complex is localized by addition of its substrate, hydrogen peroxide and an electron donor, usually diaminobenzidine(DAB). On oxidation, DAB forms an insoluble polymer which is able to chelate with osmium tetroxide becoming electron dense. Since verification of reactivity is visual, discrimination of reaction product from osmiophillic structures may be difficult. Recently, x-ray microanalysis has been applied to examine cytochemical reaction precipitates, their distribution in tissues, and to study cytochemical reaction mechanisms. For example, immunoreactive sites labelled with gold have been ascertained by means of x-ray microanalysis.

Cognitive competence at the onset of West syndrome: correlation with EEG patterns and visual function

2005 ◽  
Vol 47 (11) ◽  
pp. 760 ◽  
Author(s):  
Teresa Randò ◽  
Giovanni Baranello ◽  
Daniela Ricci ◽  
Andrea Guzzetta ◽  
Francesca Tinelli ◽  
...  
Keyword(s):  
Visual Function ◽  
West Syndrome ◽  
Cognitive Competence
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