Visual System
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| Dominant sensory modality, 15,000-20,000 sensory impulses/sec to CNS,____% are visual | 80% of sensory impulses are visual
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| Vision is the most important sense for: | Survival/early warning system, Spatio-temporal orientation, Anticipation/feed-forward planning, Visual-manual & visual-motor activities, Communication,Learning, memory, recall
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| Sight is defined as | The actual light passing through the eye
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| The projection of the image onto the retna is? | inverted and reversed
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| The light patterns turn into neuronal-electirical impulses by the ____. | Retna
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| Vision is defined as | Complex process by which the brain organizes and processes information received from eyes and executes learning and memory
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| What are the three basic layers of the eye called? | Outer, middle, inner
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| Describe the outer layer. | Continuation of Dura Mater---Forms the sclera, cornea, and sheath around the optic nerve
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| Describe the middle layer. | Analogous to the arachnoid & pia mater---Highly vascularized, secreation and absorption of aqueous humor--- Forms the pigmented choroid lining, ciliary body, ciliary muscle and the iris
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| Describe the inner layer. | Actually made up of two layers---Forms retina
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| Where is the aqeous humor located? | Aqueous humor is located in the anterior and posterior chambers---Flows and filtered similar to CSF
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| The Vitreous humor is more “gel-like”, where is it located? | Located in the interior of the eye and maintains the shape of the eye
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| What is the function of the Cornea? | Admits light to eye----Refraction
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| What is the function of the Iris? | Regulates amount of light reaching retina----Pupillary constriction/dilation
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| What is the functioin of the Lens? | Inverts and reverses image projected onto retina----30% of focusing (accommodation for near focusing)
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| What is the function of the Retina? | Converts patterns of light into action potentials----Contains the Macula, Fovea, and Optic Disc
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| The retina is composed of 5 cell types, what are they? | Photoreceptors, Bipolar cells, Horizontal cells, Amacrine cells, Ganglion cells
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| Photoreceptors refer to the ___ and ___? | Rods & Cones
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| The Ganglion cells becom the ____? | the optic nerve
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| The cell types are arranged in ___ layers? | 10
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| Rods & Cones are stimulated by? | particles of radiant energy (photons)
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| What is the function of the Cones? | Function in bright light----Specialized for high acuity & color vision
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| What is the function of the Rods? | Function in dim light----Specialized for movement detection & contrast (cannot detect color----Very sensitive
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| The ___ ___ is where ganglion axons exit eye to form optic nerve, ther are no photoreceptors or other neurons in this area and this creates a blind spot? | Optic Disc
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| The ___ is a circumferential area near lateral edge of optic disk. | Macula
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| The macula is primarily what, specialized for what? | Primarily cones; specialized for color vision
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| The ____ is a depression in center of macula. | Fovea
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| The fovea is exclusively ____, specialized for what? | Exclusively cones; specialized for highest acuity
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| The peripheral retinal areas are made of primarily what, which is specialized for what? | Primarily rods; specialized for movement detection, contrast vision
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| Each eye sees half the right visual field and half of the left visual feild (true/false)? | true
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| Each half of the visual field only has superior or inferior (true/false)? | false, there are superior and inferior divisions on each half of the of the visual field.
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| Name the structures in order of the afferent visual pathway. | Eye structures--> Optic nerve--> Optic chiasm--> Optic tract--> Lat. Geniculate neucleus--> Optic Radiations--> Primary Visual Cortex--> Visual Assoc. Areas--> Multimodal Assoc. Areas
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| In the optic nerve of the pathway, which fibers travel together? | The nasal fibers travel with the temporal fibers of the eye on that side.
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| This is the part of the afferent visual pathway in which the optic nerve decussates and the nasal fibers from each retina cross. | Optic chiasm
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| This is the part of the afferent visual pathway in which each tract contains fibers for the contralateral visual field. | Optic tract
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| This is the thalamic relay nucleus for vision that receives & processes contralateral visual field info from the optic tract. | Lateral Geniculate Nucleus
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| ____ ____ are fibers that come from the LGN through the internal capsule (retrolenticular and sublenticular parts) and project to the ___ ___ ___? | Optic radiations, primary visual cortex
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| The outer radiations carry ___ visual quadrant info and inner radiations carry ___ visual quadrant info. | superior, inferior
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| What does the Primary Visual Cortex surround? | Calcarine sulcus/ fissure
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| What Brodmanns' area is the primary visual cortex? | 17
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| The superior part of the sulcus recieves information from the ____ visual field? | inferior
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| The inferior part of the sulcus recieves info from the ___ visual field? | superior
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| The posterior portion of the primary visual cortex recieves information from our _____ vision. | Central
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| The anterior portion of the primary visual cortex recieves information form our ____ vision. | Peripheral
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| After the information is proccessed at the primary visual cortex, it sends the info to the ___ ___ ___. | visual association areas
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| The dorsal stream from the PVC to the visual assoc areas carries what information? | location and movement
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| The ventral stream from the PVC to the visual assoc areas carries what information? | color and form
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| What Broddmanns' areas are the visual assoc areas? | 18 and 19
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| The visual assoc area processes and integrates the information before sending it to the ___ ___ ___ ___ ___. | parietal-occipital-temporal assoc. area
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| The parietal-occipital-temporal assoc. area is involved with ____ & ____ ____concepts. | visuospatial and visual perceptual
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| Defecits are often named for the visual field (affected/non-affected) | affected
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| This defecit is characterized by half of the visual field being nonfunctional, right or left. | Hemianopsia
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| This visual defecit has one-quarter of the visual field nonfunctional, superior or inferior. | quadrantanopsia
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| This visual defecit is characterized by loss of the same field for each eye. | homonymous
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| This visual defecit is characterized by loss of diferent feild loss for each eye. | heteronymous
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| This visual defecit has atrophy of macular region and loss of central vision (visual acuity). | macular degeneration
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| This is a blockage of drainage of aqueous humor, increased introcular pressure --> retinal damage, and gradual loss of vision (peripheral then central). | Glaucoma
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| The partial or complete opacity of crystalline lens that contributes to blurred vision (central and peripheral) is called? | Cataracts
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| This defecit is due to trauma, disease, or prematurity. It is partial to total blindness of affected eye and loss of binocular vision --> impaired depth perception. | Retinopathies
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| If you have a lesion here, there will be blindness in the ipsilateral eye and loss of binocular vision --> impaired depth perception. | Optic Nerve
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| If there was a lesion here there would be bitemporal heteronymous hemianopsia and loss of peripheral vision bilaterally. | Optic Chiasm
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| If there were a lesion here(three places)there would be contralateral homonymous hemianopsia and loss of right or left visual field. | Optic tract, LGN, or optic radiations
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| Referring to damage at the primary visual cortex, damage to the right or left visual cortex would cause? | homonymous hemianopsia contralaterally
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| When referring to damage at the primary visual cortex, damage superior to the calcarine fissure would cause? | inferior homonymous quadrantanopia contralaterally
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| When referring to damage at the primary visual cortex, damage inferior to the calcarine fissure would cause? | superior homonymous quadrantanopia contralaterally
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| Damage to bilateral primary visual areas that causes sever blurring and sometimes swiss cheese visual fields is called? | corical blindness (both sides)
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| Damage to the visual assoc areas would cause? | visual perceptual/ visuospatial dysfunction
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| Assoc area dysfunctions may affect? | facial recognition, color recognition, movement detection, eye-hand eye-foot or eye-body coordination, knowing where you are related to surroundings, and figure-ground descrimination.
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Created by:
txst fall 2008
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