Study Guide Exam 2 Flashcards
Closed Angle Glaucoma
Angle-closure glaucoma, a less common form of glaucoma caused by blockage in the canals of scheme and results in a sudden rise in intraocular pressure. The blockage is the result of a closed or narrow angle between the iris and cornea.
Superior Colliculus
A layered structure, where superficial layers are sensory-related, and receive input from the eyes as well as other sensory systems, deep layers are motor-related, capable of activating eye movements as well as other responses, and there are also intermediate layers, with multi-sensory cells and motor properties.
The general function of the tectal system is to direct behavioral responses toward specific points in egocentric (“body-centered”) space.
Axial Hyperopia
A form of farsightedness where the eyeball is too short so the light doesn’t converge at the back of the eye like it should.
Optic Radiation
The axons going from the neurons in the lateral geniculate nucleus to the primary visual cortex.
Melanopsin Ganglion Cells
Cells which respond to melanopsin (a photopigment) and help regulate circadian rhythms.
Dichromat
“normal colorblindness,” they have 2/3 cones but are missing one kind
Hypercomplex Cells
Sensitive to angles, specifically the length of a particular line/angle.
Axial Myopia
A form of nearsightedness where the eyeball is extra long and so the light doesn’t hit the back of the eyeball like it should.
Decussaion vs. Commissure
Decussation: The action of crossing (as of nerve fibers) especially in the form of an X. Commissure: a band of nerve tissue connecting the hemispheres of the brain, the two sides of the spinal cord
Refractive Myopia
A form of nearsightedness where the cornea bends the light too much so it doesn’t hit the fovea
Blindsight
The ability to respond to visual stimuli without consciously perceiving them. This condition can occur after certain types of brain damage.
Visual Pathway from Retina to Visual Cortex
Retina Optic Nerve Optic Chiasm Optic Tract Lateral Geniculate Nucleus (in the Thalmus) Optic Radiation Primary Visual Cortex (V1)
Zeitgeber
Events that keep our circadian rhythms regulated. The alternation of the light/dark cycle of a 24-hour day is the most important natural zeitgeber. Another is the earth’s magnetic field. An alarm clock is an example of an artificial zeitgeber.
Deprivation Amblyopia
Also called lazy eye, its caused by visual stimulation failing to be transmitted through the optic nerve to the brain for a continuous period of time. It can also occur when the brain “turns off” the visual processing of one eye to prevent double-vision, for example in strabismus (crossed eyes). It often occurs during early childhood and results in poor or blurry vision
Vergence
The simultaneous movement of the pupils of the eyes toward or away from one another during focusing.
Contralateral Hemianopsia
Loss of vision on one side due to damage to the brain on the other side.
Object Agnosia
A form of visual agnosia in which a person cannot rely on visual cues to guide them directionally due to the inability to recognize objects. Nevertheless, they may still have an excellent capacity to describe the visual layout of the same place.
Detached Retina
The retina peels or detaches from the back of the eye. If not treated immediately, can cause blindness.
Refractive Hyperopia
A form of far sightedness where the cornea doesn’t bend the light enough.
Tectospinal Tract
A nerve pathway that coordinates head and eye movements.
Achromatopsia
Inability to see color
Cytochrome Oxidase
Found in the mitochondria, the more present in a cell, the more energy utilization happening
Decussation
The action of crossing (as of nerve fibers) especially in the form of an X.
Stereopsis
The perception of depth and 3-dimensional structure obtained on the basis of visual information deriving from two eyes by individuals with normally developed binocular vision
Negative Afterimage
caused by adaptation of the photoreceptors in the retina
Hyperopia
Far Sightedness; the focal point no longer hits the fovea, its too far backward, and so everything close up is blurry.
Myopia
Nearsightedness, the focal point no longer resides on the fovea-its too far forward, as a result everything far away is blurry
Simple Cortical Cells
· Cells located in the cortex which respond to angled lines.
Prosopagnosia
Aka “face blindness”
Bitemporal Hemianopsia
A type of partial blindness where vision is missing in the outer half of both eyes (peripheral vision). It is usually associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary gland.
Scotoma
An area of no vision surrounded by normal unhindered vision (a blind spot).
Pituitary Tumor
If a pituitary tumor has grown very large, a patient can develop visual loss in one or both eyes, especially reduced peripheral vision to both sides. Pituitary tumors can also cause double vision. This is due to pressure on the optic nerve.
Off center-on surround
Cells that fire when light hits the surrounding area but fire much more slowly when light hits the center as well.
Clogged Canal of Schlemm
When the Canal of Schlemm are clogged, intra-ocular pressure increases and it can lead to a open-angle glaucoma and damage to the retina.
Problems with Trichromatic Theory
Imagining mixing certain colors
Negative Afterimages
Monochromat
No cones (completely colorblind) leads to loss of foveal detection, terrible daytime vision, fuzzy vision (no visual acuity because of lots of rod convergence)
Macular Degeneration
Dry The macula deteriorates because cellular debris called drusen accumulates between the retina and the choroid, causing atrophy and scarring to the retina. Wet The macula deteriorates because blood vessels grow up from the choroid behind the retina which can leak exudate and fluid and also cause hemorrhaging.
Suprachiasmatic Nucleus
Each of a pair of small nuclei in the hypothalamus of the brain, above the optic chiasma, thought to be concerned with the regulation of physiological circadian rhythms.
Diabetic Retinopathy
Damage to blood vessels in the retina caused by either blood vessels swelling and leaking fluid or the growth of abnormal new vessels on the surface of the retina.
Difference between
Magnocellular and Parvocellular systems
Parvocellular systems ae involving the coding of shape and color. They are related to the ventral stream and project to occipital and temporal lobes. Damage to parvocellular systems results in achromatopsia and prosopagnosia.
Magnocellular system involved movement and location and is involved the dorsal stream, projecting to the parietal lope. Magnoceller is involved with balints syndrome and hemispatial neglect.
Phi Phenomena
Lilac Chaser Illusion
Consists of 12 lilac blurred discs arranged in a circle around a small black, central cross on a grey background. One of the discs disappears briefly, then the next, and the next, and so on, in a clockwise direction. When one stares at the cross for about 20 seconds or so, one sees different things.
How does visual information cross to the other side of the brain?
The nasal hemiretinas cross but the temporal hemiretinas don’t.
Cytoarchitecture
The study of the cellular composition of the body’s tissues under the microscope
Six Layers of the Lateral Geniculate Nucleus
Open Angle Glaucoma
Open-angle glaucoma is the most common form of glaucoma. Unlike a closed angle glaucoma, where the canals of scheme are constricted, the canals of schlemm are as wide and open as it should be but slowly become blocked over time, many times without the patient knowing until too late .
Edinger Westphal Nucleus
Pre-ganglion neurons that originate in the oculormotor nerve and control the iris sphincter muscle and the cilliary muscle.
Saccade vs. Nystagmus
Nystagmus: is a condition of involuntary eye movement, it is often called “dancing eyes” or “crazy eyes”
Saccade: a rapid eye movement between two fixed points.
Ishihara Plates
A type of color blindness test with more than 30 plates designed by Ishihara.
Orientation Tuning Curve
A cell responds to a specific line and a small curve surrounding the ideal line (5 degrees or so). So a line that fires at 180 might fire from 178-183 but stop dead at 184.
Cataract
A cataract is a clouding of the lens caused by a clumping of proteins.
Cataract Surgery
In cataract surgery, the lens inside your eye that has become cloudy is removed and replaced with an artificial lens. Most modern cataract procedures involve the use of a high-frequency ultrasound device that breaks up the cloudy lens into small pieces, which are then gently removed from the eye with suction.
Complex Cortical Cells
· Respond to an angle but only if the angle is moving in a specific direction.
Glaucoma
Glaucoma is complex eye disease with specific characteristics such as optic nerve damage and visual field loss. While increased pressure inside the eye (called intraocular pressure or IOP) is usually present, even patients with normal range IOP can develop glaucoma.
Hubel and Wiesel’s
Did experimens on cats, specifically on the lateral geniculate nucleus and found it fired for dots specifically. Also found other areas that fired specifically for lines and angles.
Presbyopia
Literally means “old eye,” the near point accommodation starts to change due to loss of lens elasticity.
On-Center Off-Surround
Cells that fire when light hits the center but not the surrounding area. Or if light hits both, they fire more slowly.
Saccadic Suppression
The phenomenon in visual perception where the brain selectively blocks visual processing during eye movements. It keeps us from getting dizzy or from having to constantly refocus out eyes mid-saccade
Chromotopsia
Abnormally colored vision
Optic Chiasm
Where the optic nerves from each eye merge together
Chronostasis
A type of temporal illusion in which the first impression following the introduction of a new event or task demand to the brain appears to be extended in time (clock illusion).
Aging Lenses
As our lenses age, they natuarlly get darker and less light gets let in. This is due to the buildup of various proteins including the accumulation of fluorescent chromophores. Long term buildup can lead to cataracts.
Tract vs. Nerve
A tract is a collection of nerve fibers (axons) in the central nervous system (especially in the white matter). A nerve is a collection of nerve fibers (axons) in the peripheral nervous system.
Akinetopsia
A neuropsychological disorder in which a patient cannot perceive motion in his or her visual field, despite being able to see stationary objects without issue.
Binocular Cells
Binocular neurons receive inputs from both the right and left eyes and integrate the signals together to create a perception of depth.
