Introduction to the Six Eye Movement Systems and the Visual Fixation System

Eye Movement Disorders ◽

10.1093/oso/9780195324266.003.0008 ◽

2008 ◽

Author(s):

Agnes Wong

Keyword(s):

Visual Acuity ◽

Eye Movements ◽

High Resolution ◽

Information Overload ◽

Survival Rates ◽

Large Field ◽

Field Of Vision ◽

Very High Spatial Resolution ◽

Different Characteristics ◽

The Brain

One main reason that we make eye movements is to solve a problem of information overload. A large field of vision allows an animal to survey the environment for food and to avoid predators, thus increasing its survival rate. Similarly, a high visual acuity also increases survival rates by allowing an animal to aim at a target more accurately, leading to higher killing rates and more food. However, there are simply not enough neurons in the brain to support a visual system that has high resolution over the entire field of vision. Faced with the competing evolutionary demands for high visual acuity and a large field of vision, an effective strategy is needed so that the brain will not be overwhelmed by a large amount of visual input. Some animals, such as rabbits, give up high resolution in favor of a larger field of vision (rabbits can see nearly 360°), whereas others, such as hawks, restrict their field of vision in return for a high visual acuity (hawks have vision as good as 20/2, about 10 times better than humans). In humans, rather than using one strategy over the other, the retina develops a very high spatial resolution in the center (i.e., the fovea), and a much lower resolution in the periphery. Although this “foveal compromise” strategy solves the problem of information overload, one result is that unless the image of an object of interest happens to fall on the fovea, the image is relegated to the low-resolution retinal periphery. The evolution of a mechanism to move the eyes is therefore necessary to complement this foveal compromise strategy by ensuring that an object of interest is maintained or brought to the fovea. To maintain the image of an object on the fovea, the vestibulo-ocular (VOR) and optokinetic systems generate eye movements to compensate for head motions. Likewise, the saccadic, smooth pursuit, and vergence systems generate eye movements to bring the image of an object of interest on the fovea. These different eye movements have different characteristics and involve different parts of the brain.

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OFFICE EVALUATION OF VISION IN CHILDREN

PEDIATRICS ◽

10.1542/peds.23.5.985 ◽

1959 ◽

Vol 23 (5) ◽

pp. 985-989

Author(s):

Frank Duncan Costenbader

Keyword(s):

Visual Acuity ◽

Binocular Vision ◽

Visual Image ◽

The Other ◽

Wide Field ◽

The Past ◽

Gun Barrel ◽

Field Of Vision ◽

Similar Images ◽

The Brain

I AM PLEASED to be included on a panel discussing the special senses in conjunction with intelligence and certain skills. It would seem that in so grouping these subjects, the eyes, the ears and the other senses have no longer been considered isolated phenomena but as parts of an integrated whole. It seems important at this early point in the discussion to emphasize the fact that the term "vision" is frequently misused, usually only connoting visual acuity. It should be emphasized that vision in its broadest sense includes visual acuity, the extent of the fields of vision, the normality or abnormality of binocular vision, and the adequacy of the visual associations such as recognition, identification and memory. It seems superfluous to point out that excellent visual acuity, if seen through a gun barrel, is by no means satisfying. Also, that a full, wide field of vision, when the object of interest is blurred, is most unsatisfactory. Having two eyes, each of which is a perfect unit, but not seeing together well and comfortably, is most annoying and handicapping. Finally, referring back to the brain a perfect visual image, which cannot be properly recognized and identified and then correlated with similar images previously received, is a totally frustrating experience. Thus, for a child "to see well" he must see clearly the thing he looks straight at, he must see widely the things about him, as well as the object of interest, he must have his two eyes properly co-ordinated, and he must be able to recognize, identify and associate this image with related images and activities of the past.

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Brain Mechanisms for Active Vision

Daedalus ◽

10.1162/daed_a_00314 ◽

2015 ◽

Vol 144 (1) ◽

pp. 10-21 ◽

Cited By ~ 2

Author(s):

Robert H. Wurtz

Keyword(s):

Eye Movements ◽

Visual Field ◽

High Resolution ◽

Brain Activity ◽

Active Vision ◽

Visual Disturbance ◽

Critical Function ◽

Systems Neuroscience ◽

Neuronal Systems ◽

The Brain

Active vision refers to the exploration of the visual world with rapid eye movements, or saccades, guided by shifts of visual attention. Saccades perform the critical function of directing the high-resolution fovea of our eyes to any point in the visual field two to three times per second. However, the disadvantage of saccades is that each one disrupts vision, causing significant visual disturbance for which the brain must compensate. Exploring the interaction of vision and eye movements provides the opportunity to study the organization of one of the most complex, yet best-understood, brain systems. Outlining this exploration also illustrates some of the ways in which neuroscientists study neuronal systems in the brain and how they relate this brain activity to behavior. It shows the advantages and limitations of current approaches in systems neuroscience, as well as a glimpse of its potential future.

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Visual Acuity in the Flying Snake, Chrysopelea paradisi

Integrative and Comparative Biology ◽

10.1093/icb/icaa143 ◽

2020 ◽

Author(s):

Shaz A Zamore ◽

Nicole Araujo ◽

John J Socha

Keyword(s):

Visual Acuity ◽

High Speed ◽

Closed Loop ◽

Experimental System ◽

Open Loop ◽

Visual Control ◽

Frame Rate ◽

Large Field ◽

Slow Phase ◽

Field Of Vision

Synopsis Visual control during high-speed aerial locomotion requires a visual system adapted for such behaviors. Flying snakes (genus: Chrysopelea) are capable of gliding at speeds up to 11 m s− 1 and perform visual assessments before take-off. Investigating mechanisms of visual control requires a closed-loop experimental system, such as immersive virtual arenas. To characterize vision in the flying snake Chrysopelea paradisi, we used digitally reconstructed models of the head to determine a 3D field of vision. We also used optokinetic drum experiments and compared slow-phase optokinetic nystagmus (OKN) speeds to calculate visual acuity, and conducted preliminary experiments to determine whether snakes would respond to closed-loop virtual stimuli. Visual characterization showed that C. paradisi likely has a large field of view (308.5 ± 6.5° azimuthal range), with a considerable binocular region (33.0 ± 11.0° azimuthal width) that extends overhead. Their visual systems are broadly tuned and motion-sensitive, with mean peak OKN response gains of 0.50 ± 0.11, seen at 46.06 ± 11.08 Hz, and a low spatial acuity, with mean peak gain of 0.92 ± 0.41, seen at 2.89 ± 0.16 cycles per degree (cpd). These characteristics were used to inform settings in an immersive virtual arena, including frame rate, brightness, and stimulus size. In turn, the immersive virtual arena was used to reproduce the optokinetic drum experiments. We elicited OKN in open-loop experiments, with a mean gain of 0.21 ± 0.9, seen at 0.019 ± 6 × 10−5 cpd and 1.79 ± 0.01 Hz. In closed-loop experiments, snakes did not exhibit OKN, but held the image fixed, indicating visual stabilization. These results demonstrate that C. paradisi responds to visual stimuli in a digital virtual arena. The accessibility and adaptability of the virtual setup make it suitable for future studies of visual control in snakes and other animals in an unconstrained setting.

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High-Resolution Large-Field-of-View Ultrasound Breast Imager

10.21236/ada612043 ◽

2014 ◽

Author(s):

Patrick LaRiviere

Keyword(s):

High Resolution ◽

Field Of View ◽

Large Field

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RE: A Comparison of Survival Rates for Treatment of Melanoma Metastatic to the Brain

Cancer Investigation ◽

10.1081/cnv-200027169 ◽

2004 ◽

Vol 22 (4) ◽

pp. 643-644

Author(s):

James G. Douglas ◽

Vernon K. Sondak

Keyword(s):

Survival Rates ◽

The Brain

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Application of Airy beam light sheet microscopy to examine early neurodevelopmental structures in 3D hiPSC-derived human cortical spheroids

Molecular Autism ◽

10.1186/s13229-021-00413-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Dwaipayan Adhya ◽

George Chennell ◽

James A. Crowe ◽

Eva P. Valencia-Alarcón ◽

James Seyforth ◽

...

Keyword(s):

High Resolution ◽

Human Brain ◽

Light Sheet ◽

Autism Spectrum ◽

Model Systems ◽

Large Field ◽

Autism Spectrum Conditions ◽

Patient Specific ◽

Airy Beam

Abstract Background The inability to observe relevant biological processes in vivo significantly restricts human neurodevelopmental research. Advances in appropriate in vitro model systems, including patient-specific human brain organoids and human cortical spheroids (hCSs), offer a pragmatic solution to this issue. In particular, hCSs are an accessible method for generating homogenous organoids of dorsal telencephalic fate, which recapitulate key aspects of human corticogenesis, including the formation of neural rosettes—in vitro correlates of the neural tube. These neurogenic niches give rise to neural progenitors that subsequently differentiate into neurons. Studies differentiating induced pluripotent stem cells (hiPSCs) in 2D have linked atypical formation of neural rosettes with neurodevelopmental disorders such as autism spectrum conditions. Thus far, however, conventional methods of tissue preparation in this field limit the ability to image these structures in three-dimensions within intact hCS or other 3D preparations. To overcome this limitation, we have sought to optimise a methodological approach to process hCSs to maximise the utility of a novel Airy-beam light sheet microscope (ALSM) to acquire high resolution volumetric images of internal structures within hCS representative of early developmental time points. Results Conventional approaches to imaging hCS by confocal microscopy were limited in their ability to image effectively into intact spheroids. Conversely, volumetric acquisition by ALSM offered superior imaging through intact, non-clarified, in vitro tissues, in both speed and resolution when compared to conventional confocal imaging systems. Furthermore, optimised immunohistochemistry and optical clearing of hCSs afforded improved imaging at depth. This permitted visualization of the morphology of the inner lumen of neural rosettes. Conclusion We present an optimized methodology that takes advantage of an ALSM system that can rapidly image intact 3D brain organoids at high resolution while retaining a large field of view. This imaging modality can be applied to both non-cleared and cleared in vitro human brain spheroids derived from hiPSCs for precise examination of their internal 3D structures. This process represents a rapid, highly efficient method to examine and quantify in 3D the formation of key structures required for the coordination of neurodevelopmental processes in both health and disease states. We posit that this approach would facilitate investigation of human neurodevelopmental processes in vitro.

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Choroidal metastases: case report and review

Journal of Radiotherapy in Practice ◽

10.1017/s1460396920001090 ◽

2020 ◽

pp. 1-7

Author(s):

Victor Duque ◽

Carolina de la Pinta ◽

Ciriaco Corral ◽

Carmen Vallejo ◽

Margarita Martin ◽

...

Keyword(s):

Visual Acuity ◽

Side Effects ◽

External Beam Radiotherapy ◽

Choroidal Metastasis ◽

Good Visual Acuity ◽

Good Local Control ◽

Radiological Response ◽

The Right ◽

The Brain

Abstract Introduction: Choroidal metastases are the most frequent intraocular secondary tumours, with a prevalence of 2–7% according to the literature. Our aim was to review a clinical case of choroidal metastasis. We present a case of a 63-year-old male patient diagnosed in 2018 with lung adenocarcinoma cT4N0M1. The patient had three metastases in the brain, which were successfully treated with radiosurgery (RS). The patient was treated with chemotherapy with pemetrexed–cisplatin schedule. Five months after diagnosis, the patient presented with decreased vision in the right eye. After ophthalmologic evaluation, he was diagnosed with a right choroidal metastasis, which was treated with external beam radiotherapy with 20 Gy in five fractions, resulting in improved visual acuity and a complete clinical and radiological response. The patient took part in a clinical trial that continued with systemic chemotherapy. Twenty-two months after radiotherapy to the eye, the patient has good visual acuity without any side effects. Conclusions: Choroidal metastasis treated with radiotherapy achieves good local control, with limited side effects, allowing an improvement in visual acuity and consequently, an improvement in the patient´s quality of life.

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Glioma Revisited: From Neurogenesis and Cancer Stem Cells to the Epigenetic Regulation of the Niche

Journal of Oncology ◽

10.1155/2012/537861 ◽

2012 ◽

Vol 2012 ◽

pp. 1-20 ◽

Cited By ~ 17

Author(s):

Felipe de Almeida Sassi ◽

Algemir Lunardi Brunetto ◽

Gilberto Schwartsmann ◽

Rafael Roesler ◽

Ana Lucia Abujamra

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

Cellular Proliferation ◽

Survival Rates ◽

Comprehensive Analysis ◽

Heterogeneous Population ◽

Aggressive Tumor ◽

Epigenetic Modulation ◽

The Brain

Gliomas are the most incident brain tumor in adults. This malignancy has very low survival rates, even when combining radio- and chemotherapy. Among the gliomas, glioblastoma multiforme (GBM) is the most common and aggressive type, and patients frequently relapse or become refractory to conventional therapies. The fact that such an aggressive tumor can arise in such a carefully orchestrated organ, where cellular proliferation is barely needed to maintain its function, is a question that has intrigued scientists until very recently, when the discovery of the existence of proliferative cells in the brain overcame such challenges. Even so, the precise origin of gliomas still remains elusive. Thanks to new advents in molecular biology, researchers have been able to depict the first steps of glioma formation and to accumulate knowledge about how neural stem cells and its progenitors become gliomas. Indeed, GBM are composed of a very heterogeneous population of cells, which exhibit a plethora of tumorigenic properties, supporting the presence of cancer stem cells (CSCs) in these tumors. This paper provides a comprehensive analysis of how gliomas initiate and progress, taking into account the role of epigenetic modulation in the crosstalk of cancer cells with their environment.

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