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56 Cards in this Set
- Front
- Back
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cornea
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gross focusing
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lens
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fine adjustments
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retinal ganglion cells
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axons form the optic nerve
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iris
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controls the size of the pupil
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visual pathway
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optic chiasm->lateral geniculate nucleus->optic radiation-> primary visual cortex
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occipital pole
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portion of visual cortex that represents teh fovea
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calcarine sulcus
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location of the primary visual cortex
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superior colliculus
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located in dorsal midbrain, receives fibers from the optic chiasm
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lesions
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anterior to OC: monocular
posterior to OC: binocular in hemifield contralateral to lesion |
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pigment epithelium
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behind the retina
-re-isomerizes rhodopsin, cone opsin for photoreceptor membranous discs |
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optic cup
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outpocketing of the diencephalon that gives rise tot he retina and PE
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cone
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daytime, color vision. concentrated at fovea
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rod
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nocturnal, black/white vision. absent from fovea
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transducin
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located in membranous discs of photoreceptors. photon absorption, ultimately leading to hyperpolarization
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bipolar cells
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relay from photoreceptors to retinal ganglion cells
-located between outer and inner plexiform layers |
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outer plexiform layer
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photoreceptor termini
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inner plexiform layer
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contacts between bipolar cells and retinal ganglion cell dendrites
-contains amacrine cells |
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ganglion cell layer
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retinal ganglion cell bodies
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amacrine cells
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convey signals laterally within the retina within the inner plexiform layer
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inner nuclear layer
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amacrine cell bodies
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horizontal cells
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convey signals laterally within the outer plexiform layer
-determine on-center and off-center sensitivity of bipolar cells |
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on-center cells
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retinal ganglion/bipolar cells.
increase firing w/ field center illuminated, decrease w/ periphery illuminated. neutral when all illuminated |
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off-center cells
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retinal ganglion/bipolar cells.
decrease firing when center illuminated, increase when periphery illuminated |
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parvocellular (P) ganglion
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more numerous. smaller, higher resolution, slow change, color
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magnocellular (M) ganglion
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fewer, larger, low resolution, rapid change, achromatic
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LGN
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laminated layers represent two eyes
-four P layers, two M layers -on-center and off-center segregation of P layers -topographical map of contralateral hemifield -each LGN cell driven by one optic nerve axon -maps are in register in the visual field |
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Superior colliculus
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eye motor control
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Suprachiasmatic nucleus
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circadian rhythm control
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pretectal nucleus
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simple reflex loop for papillary constriction/lens accomodation
-project to accessory oculomotor nucleus-->ciliary ganglia |
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Striate cortex
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V1. calcarine sulcus
-receptive field different from retina/LGN -LGN input enters at Layer 4C -occular dominance columns |
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simple cells
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in V1, contain spatially antagonistic subregions
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complex cells
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no antagonistic subregions
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inferotemporal cortex
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ventral to V1, involved in pattern recognition and memory
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posterior parietal cortex
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dorsal to occipital lobe
-analysis of spatial relations -controls attention and visual guided movements |
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V1 blobs
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contain orientation-insensitive, color-sensitive cells projecting to V2 thin stripes
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V1 interblobs (cytochrome oxidase)
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contain orientation-sensitive cells that project to V2 interstripes
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V1 layer 4B
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orientation-sensitive, direction-sensitive cells projecting to V2 thick stripes (motion pathway)
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MT
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selective for motion sensation
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MST
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selective for rotation, expansion, contraction
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developmental sequence
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1.eyes
2.retinal ganglion cells 3.LGN 4.V1 (from lateral ventricle neuroepithelium) 5.connections develop after migration 6. V1->V2 connections continue postnatal |
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binocular disparity development
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V1 4B matures by 4mo postnatal (more superficial layers w/ visual info comparison matures later)
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ODC development
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segregation complete at birth.
-maintained by normal binocular vision during critical period |
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amblyopia
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poor vision through one eye
-may be caused by cataract in critical period |
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scotoma
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blind spot caused by lesion in the visual pathway
-can be caused by retinal lesions |
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saccade
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rapid eye movement
-latency 0.2 sec -span 0.05 sec |
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smooth pursuit
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match eye velocity to moving targets
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vergence
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align foveas to distance targets
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diplopia
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seeing double
-drives vergence |
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vestibular ocular reflex
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stabilizes vision as head moves
-works well w/ fast turn, poorly w/ slow or prolonged turn -'open loop:' afferent bipolar vestibular->interneuron->efferent neuron |
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optokinetics
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supplements VOR for prolonged rotation
-evoked by retinal slipping -'closed loop:' from retina-> visual cortex->brainstem -feeds into VOR efferents before contact w/ oculomotor |
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nystagmus
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VOR and OK consisting of smooth movements and flicks
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strabismus
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visual axes deviation nasal/temporal
-if in newborn, will view w/ either eye as adult -lose binocular disparity -V1 neurons respond to only one eye -horizontal connections (4B) are lost |
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amblyopia
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ODC development prenatal, but refined postnatally.
-metabolic activity increases in dominant ODC, radius increases as well |
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VOR interneuron
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located in vestibular nucleus of the pons
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VOR efferent neuron
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soma located in extraocular motor nucleus of pons/midbrain
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otolith organs
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detect linear acceleration
-govern VOR for depth perception adjustments |
