Plasticity in the developing visual system: The effects of retinal lesions made in young rats

2004 ◽  
Vol 169 (2) ◽  
pp. 133-154 ◽  
Author(s):  
Raymond D. Lund ◽  
Jennifer S. Lund
Keyword(s):  
Visual System ◽  
Retinal Lesions ◽  
Young Rats ◽  
Made In

Topographic map reorganization in cat area 17 after early monocular retinal lesions

2002 ◽  
Vol 19 (1) ◽  
pp. 85-96 ◽  
Author(s):  
KAZUKI MATSUURA ◽  
BIN ZHANG ◽  
TAKAFUMI MORI ◽  
EARL L. SMITH ◽  
JON H. KAAS ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Receptive Fields ◽  
Optic Disk ◽  
Area 17 ◽  
Topographic Map ◽  
Retinal Lesions ◽  
The World ◽  
Blind Spots ◽  
Made In

Neither discrete peripheral retinal lesions nor the normal optic disk produces obvious holes in one's percept of the world because the visual brain appears to perceptually “fill in” these blind spots. Where in the visual brain or how this filling in occurs is not well understood. A prevailing hypothesis states that topographic map of visual cortex reorganizes after retinal lesions, which “sews up” the hole in the topographic map representing the deprived area of cortex (cortical scotoma) and may lead to perceptual filling in. Since the map reorganization does not typically occur unless retinotopically matched lesions are made in both eyes, we investigated the conditions in which monocular retinal lesions can induce comparable map reorganization. We found that following monocular retinal lesions, deprived neurons in cat area 17 can acquire new receptive fields if the lesion occurred relatively early in life (8 weeks of age) and the lesioned cats experienced a substantial period of recovery (>3 years). Quantitative determination of the monocular and binocular response properties of reactivated units indicated that responses to the lesioned eye for such neurons were remarkably robust, and that the receptive-field properties for the two eyes were generally similar. Moreover, excitatory or inhibitory binocular interactions were found in the majority of experimental units when the two eyes were activated together. These results are consistent with the hypothesis that map reorganization after monocular retinal lesions require experience-dependent plasticity and may be involved in the perceptual filling in of blind spots due to retinal lesions early in life.

Effects of retinal lesions upon the distribution of nicotinic acetylcholine receptor subunits in the chick visual system

1994 ◽  
Vol 350 (3) ◽  
pp. 473-484 ◽  
Author(s):  
L. R. G. Britto ◽  
A. S. Torrao ◽  
D. E. Hamassaki-Britto ◽  
J. Mpodozis ◽  
K. T. Keyser ◽  
...  
Keyword(s):  
Visual System ◽  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Nicotinic Acetylcholine ◽  
Retinal Lesions

Technology Study on the Different Cognitive Process of Stereopsis between Crossed and Uncrossed Fine Disparity

2014 ◽  
Vol 886 ◽  
pp. 374-377
Author(s):  
Yan Wu ◽  
Qi Li
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Cognitive Process ◽  
Three Dimensional ◽  
Reaction Times ◽  
Visual Fatigue ◽  
Technology Study ◽  
Random Dot Stereograms ◽  
Display Technology ◽  
Made In

Considerable improvements in display technology were made in stereoscopic imaging and image quality rose with technical progress. But there was not enough effort on reducing visual fatigue. The study was to investigate one of the ways to reduce visual fatigue caused by three-dimensional images. Static random-dot stereograms (RDS) were used as stimuli. The performance of every subject was recorded with disparate disparities of 3.27', 6.54', 8.18', 11.45', 14.72', 17.99', 21.26', and 24.53'. Results showed that reaction times were always longer in the uncrossed disparities relative to the crossed disparities. For crossed disparities, human visual system was the most sensitive to the images with disparity of 6.54'. As to uncrossed disparities, human visual system was the most sensitive to the images with disparity of 8.18'.

Long-term effects of retinal lesions on growth-associated protein 43 (GAP-43) expression in the visual system of adult cats

1996 ◽  
Vol 208 (2) ◽  
pp. 113-116 ◽  
Author(s):  
Veerle Baekelandt ◽  
Ulf T. Eysel ◽  
Guy A. Orban ◽  
Frans Vandesande
Keyword(s):  
Visual System ◽  
Long Term Effects ◽  
Retinal Lesions ◽  
Adult Cats

scholarly journals Coordination between stochastic and deterministic specification in the Drosophila visual system

2019 ◽  
Author(s):  
Maximilien Courgeon ◽  
Claude Desplan
Keyword(s):  
Visual System ◽  
Cell Adhesion Molecules ◽  
Stochastic Choice ◽  
Fate Specification ◽  
Qualitative And Quantitative ◽  
Neuronal Progenitors ◽  
Neuronal Types ◽  
The Brain ◽  
Postsynaptic Target ◽  
Made In

AbstractMany sensory systems use stochastic fate specification to increase their repertoire of neuronal types. How these stochastic decisions are coordinated with the development of their target post-synaptic neurons in processing centers is not understood. In the Drosophila visual system, two subtypes of the UV-sensitive R7 color photoreceptors called yR7 and pR7 are stochastically specified in the retina. In contrast, the target neurons of photoreceptors in the optic lobes are specified through a highly deterministic program. Here, we identify subtypes of the main postsynaptic target of R7, the Dm8 neurons, that are each specific to the different subtypes of R7s. We show that during development the different Dm8 subtypes are produced in excess by distinct neuronal progenitors, independently from R7 subtype specification. Following matching with their respective R7 target, supernumerary Dm8s are eliminated by apoptosis. We show that the two interacting cell adhesion molecules Dpr11, expressed in yR7s, and its partner DIPγ, expressed in yDm8s, are essential for the matching of the synaptic pair. Loss of either molecule leads to the death of yDm8s or their mis-pairing with the wrong pR7 subtype. We also show that competitive interactions between Dm8 subtypes regulate both cell survival and targeting. These mechanisms allow the qualitative and quantitative matching of R7 subtypes with their target in the brain and thus permit the stochastic choice made in R7 to propagate to the deterministically specified downstream circuit to support color vision.

Effects of serial lesions of telencephalic components of the visual system in pigeons

1988 ◽  
Vol 1 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Nell M. Riley ◽  
William Hodos ◽  
Tatiana Pasternak
Keyword(s):  
Visual System ◽  
Visual Processing ◽  
Pattern Discrimination ◽  
Color Intensity ◽  
Sequence Of Events ◽  
Serial Lesion ◽  
Avian Visual System ◽  
The One ◽  
Tectofugal Pathway ◽  
Made In

AbstractA serial-lesion technique was used to investigate interactions in visual processing between telencephalic components of the pigeon visual system. Pigeons were trained to discriminate pairs of stimuli that differed in color, intensity or pattern. After mastering the discrimination tasks, they were assigned to one of three groups. The first group (WI-EII) received lesions of the visual Wulst and were retested. After the discrimination tasks were again mastered, a second set of lesions was made, this time in the ectostriatum. The birds were tested once again after the second surgery. The second group (EI-WII), underwent the same sequence of events except that the order of the lesions was reversed. In the third group (E + W), lesions of both the visual Wulst and ectostriatum were made in a single operation, followed by retesting. The performance after the first lesion of the subjects in each of the two-stage lesion groups was typical of performance after such lesions; i.e. the birds with visual-Wulst lesions showed little or no impairment on any of the tasks, whereas the pigeons with ectostriatum lesions showed considerable deficits in intensity and pattern discrimination, which diminished after prolonged retraining. In contrast, the pigeons in the one-stage group (E + W) showed profound deficits that appeared to be permanent. The performance after the second operation of the WI-EII group was the same as that of pigeons with lesions of ectostriatum alone; i.e. destruction of ectostriatum first or second resulted in the same duration of impairment. The performance of the EI-WII group after its visual Wulst lesion, however, was similar to that observed in the E + W group. The results are interpreted as a reflection of parallel processing within the avian visual system; i.e. the presence of an intact tectofugal pathway may mask the effects of thalamofugal pathway interruption.

scholarly journals EFFECT OF ACUPUNCTURE ON THE FUNCTION OF THE VISUAL SYSTEM IN PATIENTS OF GLAUCOMA

2018 ◽  
Vol 3 (5) ◽  
pp. 72-75
Author(s):  
I. V. Valueva ◽  
O. Yu. Kirgizova
Keyword(s):  
Intraocular Pressure ◽  
Optic Nerve ◽  
Visual System ◽  
Conservative Therapy ◽  
Open Angle Glaucoma ◽  
Visual Functions ◽  
Severe Stage ◽  
Neuroprotective Therapy ◽  
Adequate Blood Supply ◽  
Made In

At present, significant advances have been made in the surgical and conservative treatment of glaucoma. However, in patients with a prolonged course of the disease, even against the background of normalized intraocular pressure, progressive deterioration of visual functions occurs with the transition of the disease to a more severe stage. Effects directed solely at lowering the intraocular pressure are not able to fully ensure the preservation of visual functions, so its normalization cannot ensure the stabilization of the glaucoma process. Dysfunction of the nervous system and vascular disorders play a significant role in the pathogenesis of glaucoma. In this regard, the treatment of this disease should be comprehensive and include neuroprotective therapy aimed at correction of metabolic disorders that occur in glaucoma in the optic nerve head, improvement of local microcirculation and trophism of tissues, normalization the rheological properties of the blood. Conventional conservative therapy does not provide adequate blood supply to the optic nerve and prevent the deterioration of visual functions in more than half of patients. The purpose of this study was to study the effectiveness of reflexotherapy in patients with glaucoma after surgery and normalization of intraocular pressure. In the study, 18 patients with a diagnosis of primary open-angle glaucoma were treated. It has been established that reflexotherapy improves significantly the functions of the visual system and the general condition, normalizes arterial pressure and psycho-emotional state of patients.

Neuro-ophthalmologic Manifestations of Multiple Sclerosis

2016 ◽  
Author(s):  
Shin C. Beh ◽  
Elliot M. Frohman ◽  
Teresa Frohman
Keyword(s):  
Multiple Sclerosis ◽  
Eye Movements ◽  
Visual System ◽  
Visual Pathway ◽  
Ophthalmic Manifestations ◽  
Trial Outcomes ◽  
Visual Cortices ◽  
Visual Electrophysiology ◽  
Saccadic Intrusions ◽  
Made In

The inflammatory, demyelinating plaques that characterize multiple sclerosis (MS) frequently affect the visual pathways. Lesions of the afferent visual pathway (most commonly optic neuritis) result in problems conveying visual stimuli from the retina to the visual cortices. Lesions affecting the efferent visual system result in ocular dysmotility that impairs visual acuity by disrupting the precision of binocular eye movements or by causing excessive eye movements that prevent adequate foveation (e.g. nystagmus, saccadic intrusions). Significant advancements have been made in the techniques used to interrogate both the structural and the functional integrity of the visual system to dissect the pathobiological underpinnings of multiple sclerosis and to design better biomarkers and clinical trial outcomes. This chapter discusses the neuro-ophthalmic manifestations of multiple sclerosis, revolutionary advancements in optical coherence tomography and visual electrophysiology, and therapies for treating visual dysfunction in multiple sclerosis.

Radio-Astronomy and Navigation

1958 ◽  
Vol 62 (575) ◽  
pp. 805-828 ◽  
Author(s):  
C. M. Cade
Keyword(s):  
Great Britain ◽  
Visual System ◽  
Radio Astronomy ◽  
Weather Conditions ◽  
The Sun ◽  
Adverse Weather Conditions ◽  
Adverse Weather ◽  
Practical Design ◽  
Design Factors ◽  
Made In

The difficulties of determining latitude and longitude under adverse weather conditions, when neither the Sun nor stars can be sighted, are well-known, and the advantages of a non-visual system of position finding which could operate through clouds or fog are too obvious to require emphasis.A Radio Sextant, which detects and locks-on to 8 mm. radiation from the Sun, has already been made and tested in America with reputedly excellent results. An analysis of both the theoretical and the practical design factors is given in the present paper, together with the results of successful experiments made in Great Britain.

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