Term
| Retina has 4 cell layers: |
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Definition
Pigment cell layer
Layer of rods + cones
Ganglion Cell Layer
Fovea |
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Term
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Definition
produces blind spot
exit of the optic nerve |
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Term
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Definition
| contains central fovea (pit) |
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Term
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Definition
derive from choroid
attaches retina to eyeball
absorbs stray light |
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Term
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Definition
130 million
periphery of retina
low light vision + perception of movement
much convergence of information before relay to CNS |
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Term
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Definition
7 million
central rentina
The fovea contains only cones, the area of max visual acuity, color and brightness discrimination.
little or no convergence of information |
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Term
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Definition
final point of convergence in retina
myelinated axons of these cells form the optic nerve |
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Term
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Definition
contains features that result in minimum interference between light sourceand cones for max visual acuity
light does not have to pass through a number of cell layers before it activates the cones
avascular
nerve + vessels detour around it. |
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Term
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Definition
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Term
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Definition
| bending of light rays reaching the surface of the cornea |
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Term
| an inverted image of an object is focused on the ______ |
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Definition
| an inverted image of an object is focused on the RETINA |
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Term
Light is refracted by:
_(1)_
_(2)_
_(3)_
_(4)_ |
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Definition
Light is refracted by:
CORNEA
AQUEOUS HUMOR
LENS
VITREOUS HUMOR |
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Term
| The _____ is where the image is inverted |
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Definition
| The LENS is where the image is inverted |
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Term
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Definition
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Term
| changes in refractive power are accomplished by changing the _____ of the _____ |
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Definition
| changes in refractive power are accomplished by changing the SHAPE of the LENS |
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Term
| The lens changes shape, ______ for close viewing, _______ for distant viewing |
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Definition
| The lens changes shape, ROUNDER for close viewing, FLATTER for distant viewing |
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Term
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Definition
| the change in refractive power which allows the viewing of near objects |
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Term
| to view a near object, the lens must increase it's ________ power by becoming more _________ (________) |
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Definition
| to view a near object, the lens must increase it's REFRACTIVE power by becoming more CONVEX (ROUNDER) |
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Term
| At rest the lens is held in a _____ shape by the ________ fibers that connect it to the ________ muscle. |
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Definition
| At rest the lens is held in a FLAT shape by the SUSPENSORY fibers that connect it to the CILIARY muscle. |
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Term
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Definition
connects lens to ciliary muscle
holds lens in a flat shape |
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Term
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Definition
| contracts, reducing the tension on suspensory fibers to accomodate during near vision |
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Term
| to accommodate during ____ vision, the _____ muscle contracts, ______ the tension on suspensory fibers |
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Definition
| to accommodate during NEAR vision, the CILIARY muscle contracts, REDUCING the tension on suspensory fibers |
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Term
| contraction of the ciliary muscle is controlled by ___________ _____ _____ |
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Definition
| contraction of the ciliary muscle is controlled by PARASYMPATHETIC NERVE FIBERS |
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Term
| during accommodation, the pupillary diameter _____ in order to keep the image of the object sharper |
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Definition
| during accommodation, the pupillary diameter DECREASES in order to keep the image of the object sharper |
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Term
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Definition
| the normally occurring condition in which the image of an object is focused on the retinal surface. |
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Term
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Definition
far0sightedness
the focal point falls behind the retinal surface |
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Term
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Definition
near sightedness
if the object falls in front of the retina |
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Term
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Definition
| the loss of lens elasticity noted with age |
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Term
there are _#_ types of photoreceptors
_____ + ____ |
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Definition
there are 2 types of photoreceptors
RODS + CONES |
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Term
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Definition
used for low light
dim conditions |
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Term
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Definition
used for high light
color vision |
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Term
| Rods have a ______ excitation threshold and thereofore used in ___ conditions. Rod acuity is _____. |
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Definition
| Rods have a LOW excitation threshold and thereofore used in DIM conditions. Rod acuity is POOR. |
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Term
| Cones have a _____ excitation threshold, and are used in _____ _____ conditions. Acuity is ____ and cones provide ______ vision. |
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Definition
| Cones have a HIGH excitation threshold, and are used in HIGH LIGHT conditions. Acuity is HIGH and cones provide COLOR vision. |
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Term
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Definition
the ability to distinguish color due to the presence of 3 separate cone populations:
blue
green
red |
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Term
| color blindness is the result of the _______ of one or more of the _______ populations |
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Definition
| color blindness is the result of the ABSENCE of one or more of the CONE populations |
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Term
| generator potentials originating in receptors are transmitted to______ cells |
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Definition
| generator potentials originating in receptors are transmitted to BIPOLAR cells |
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Term
| Pathway of generator potentials originating in receptors and then altered by other cells in the retina are separated into 2 systems |
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Definition
Vertical system
signals pass from receptors to bipolar cells to ganglion cells
Horizontal system
horizontal and amacrine cells provide lateral inhibition between the different vertical system components |
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Term
| ganglion cell function- retina |
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Definition
the final stage of retinal processing
transmits info to subcortical visual centers in the brain
form the optic nerve
respond to the presence of absence of light |
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Term
| retina ganglion cells transmit information to: |
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Definition
| subcortical visual centers |
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Term
retina ganglion cells
axons form what? |
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Definition
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Term
Receptive field
definition |
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Definition
| the corresponding area of retinal surface which, upon illumination, influences the signaling of that neuron |
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Term
| ganglion cells exhibit a _____ resting discharge in the dark. |
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Definition
| ganglion cells exhibit a SLOW resting discharge in the dark. |
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Term
| Most ganglion cell RF's are organized in _______ fashion |
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Definition
| Most ganglion cell RF's are organized in CONCENTRIC fashion |
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Term
| Ganglion cells are classified as _______ or ________ depending on how they respond to a spot of light striking the center of the receptive field |
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Definition
| Ganglion cells are classified as ON-CENTER or OFF-CENTER depending on how they respond to a spot of light striking the center of the receptive field |
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Term
| Ganglion cell subdivisions |
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Definition
Sustained ganglion cells
Transient ganglion cells |
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Term
| Ganglion cells correspond to: |
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Definition
M-cells (larger ganlgion cells)
P-Cells (smaller ganglion cells) |
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Term
| M- cells are concerned with: |
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Definition
signaling changes in the scene being viewed including movement
changes in light and dark contrast |
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Term
| P-Cells provide info about: |
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Definition
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Term
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Definition
| respond as long as the stimulus remains within the RF |
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Term
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Definition
| respond only when the light is turned on or off |
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Term
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Definition
responds poorly to visual stimuli
concerned with eye and head movement in space |
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Term
| information that is transmitted from the eye through the optic nerve must eventually reach the _______ to be perceived. |
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Definition
| information that is transmitted from the eye through the optic nerve must eventually reach the CORTEX to be perceived. |
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Term
Central visual pathways are divided into:
______ pathways +
______ pathways |
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Definition
Central visual pathways are divided into:
PRIMARY pathways +
SECONDARY pathways |
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Term
| the visual field is represented___________ on the retina |
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Definition
| the visual field is represented TOPOGRAPHICALLY on the retina |
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Term
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Definition
| When a visual field is divided by a vertical line at the fixation point into a left and right hemifield |
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Term
| separation of hemifields is accomplished at the level of the ______ ______ |
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Definition
| separation of hemifields is accomplished at the level of the OPTIC CHIASM |
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Term
| Each half of the brain receives information only from the _________ hemifield |
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Definition
| Each half of the brain receives information only from the CONTRALATERAL hemifield |
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Term
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Definition
| images of the visual world composed of information from the 2 eyes. |
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Term
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Definition
| when information from each of the 2 eyes (binocular) are merged to form a single image |
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Term
| both eyes viewing the same or corresponding visual field is termed ___________ visual fields |
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Definition
| both eyes viewing the same or corresponding visual field is termed HOMONYMOUS visual fields |
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Term
| In contralateral homonymous perception, the ______ primary visual cortex (area 17) is perceiving only the left half of the visual field |
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Definition
| In contralateral homonymous perception, the RIGHT primary visual cortex (area 17) is perceiving only the left half of the visual field |
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Term
| Everything ______ to the optic chiasm is carrying contralateral homonymous sensation |
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Definition
| Everything CAUDAL to the optic chiasm is carrying contralateral homonymous sensation |
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Term
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Definition
| loss of visual perception |
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Term
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Definition
| loss of visual perception of half of the entire visual field |
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Term
| this term, as it applies to visual fields, describes each individual eye viewing from different visual fields |
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Definition
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Term
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Definition
| different halves, describes each individual eye viewing different visual fields |
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Term
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Definition
| when each eye is only able to see the ipsilateral temporal visual field and no the nasal visual fields |
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Term
| in the Primary visual pathway, the optic nerve fibers from Temporal Retina ( nasal visual hemifield) course caudally along the _____ edge of the: _(1)_, _(2)_, and _(3)_ to the _______ LGN |
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Definition
| in the Primary visual pathway, the optic nerve fibers from Temporal Retina (nasal visual hemifield) course caudally along the LATERAL edge of the: OPTIC NERVE, OPTIC CHIASM, and OPTIC TRACT to the IPSILATERAL LGN |
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Term
| in the Primary visual pathway, fibers from Nasal Retina (temporal visual hemifield) course caudally along the ______ edge of the _(1)_ and cross in the ______ then continue to course along the _____ edge of the _(2)_ to the _________ LGN |
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Definition
| in the Primary visual pathway, fibers from Nasal Retina (temporal visual hemifield) course caudally along the MEDIAL edge of the OPTIC NERVE and cross in the OPTIC CHIASM then continue to course along the MEDIAL edge of the OPTIC TRACT to the CONTRALATERAL LGN |
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Term
| In the primary visual pathway, fibers from the lower nasal retina (upper temporal visual quarterfield), after crossing in the ______ loop forward into the ________ optic nerve are termed ___________ _____ before turning caudally. |
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Definition
| In the primary visual pathway, fibers from the lower nasal retina (upper temporal visual quarterfield), after crossing in the OPTIC CHIASM loop forward into the CONTRALATERAL optic nerve are termed WILLBRANDT'S KNEE before turning caudally. |
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Term
| in the primary visual pathway, fibers from the upper retina (lower visual hemifield) course _____ along the _____ edge of the _(1)_, _(2)_, and _(3)_ |
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Definition
| in the primary visual pathway, fibers from the upper retina (lower visual hemifield) course CAUDALLY along the DORSAL edge of the OPTIC NERVE, OPTIC CHIASM, and OPTIC TRACT |
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Term
| retinogeniculate fibers carrying information from the more peripheral visual fields are located most _________ within the _(1)_, _(2)_, and _(3)_ |
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Definition
| retinogeniculate fibers carrying information from the more peripheral visual fields are located most SUPERFICIALLY within the OPTIC NERVE, OPTIC CHIASM, and OPTIC TRACT |
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Term
| retinogeniculate fibers carrying information from the more central visual fields are located more _________ within the _(1)_, _(2)_, and _(3)_ |
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Definition
| retinogeniculate fibers carrying information from the more central visual fields are located more _________ within the OPTIC NERVE, OPTIC CHIASM, and OPTIC TRACT |
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Term
| After the optic nerve fibers pass through the ______ they continue as the _______ and end primarily (80%) in the ___ with some (20%) terminating in the _______ via the ______ _ _ _____ _____ |
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Definition
| After the optic nerve fibers pass through the OPTIC CHIASM they continue as the OPTIC TRACT and end primarily (80%) in the LGN with some (20%) terminating in the MIDBRAIN via the BRACHIUM OF THE SUPERIOR COLLICULUS (BSC) |
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Term
| After primary visual pathway synapses in the LGN nerve impulses proceed to the ____ ____ ____ (area __) by way of _____ _____ |
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Definition
| After primary visual pathway synapses in the LGN nerve impulses proceed to the PRIMARY VISUAL CORTEX (area 17) by way of VISUAL RADIATIONS |
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Term
| Geniculocalcarine fibers carrying visuotpic information from the upper halves of both retinae (lower visual hemifields) course directly _________ around the _______ _______ as the ___________ limb of the ________ capsule to reach the _________ _____ _ _ ________ _____ (______) |
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Definition
| Geniculocalcarine fibers carrying visuotpic information from the upper halves of both retinae (lower visual hemifields) course directly BACKWARDS around the LATERAL VENTRICLE as the RETROLENTICULAR limb of the INTERNAL capsule to reach the SUPERIOR BANK OF THE CALCARINE FISSURE(CUNEUS) |
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Term
| Geniculocalcarine fibers carrying visuotpic information from the lower halves of the retinae (upper visual hemifields) course _________ toward the tip of the ________ ____ of the _________ ______ then loop inf + backwrd in the temporal lobe to reach the _________ ____ _ _ _______ ______ (________ _____), this loop is called ______ ________ |
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Definition
| Geniculocalcarine fibers carrying visuotpic information from the lower halves of the retinae (upper visual hemifields) course FORWARD toward the tip of the TEMPORAL HORN of the LATERAL VENTRICLE then loop inf + backward in the temporal lobe to reach the INFERIOR BANK OF THE CALCARINE FISSURE (LINGUAL GYRUS), this loop is called MEYER'S LOOP |
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Term
| Contralteral Upper Homonymous Quadrantanopia is damage to what? |
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Definition
| Contralteral Upper Homonymous Quadrantanopia is damage to MEYER'S LOOP |
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Term
| The primary visual cortex contains an orderly map of the ____________ visual field, which it receives from neurons of the ___ |
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Definition
| The primary visual cortex contains an orderly map of the CONTRALATERAL visual field, which it receives from neurons of the LGN |
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Term
| The orderly map of the contralteral visual vield in the primary visual cortex is arranged so that the central visual field is represented in the ________ ______ of the ________ ____ |
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Definition
| The orderly map of the contralteral visual vield in the primary visual cortex is arranged so that the central visual field is represented in the POSTERIOR POLE of the OCCIPITAL LOBE |
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Term
| The orderly map of the contralteral visual vield in the primary visual cortex is arranged so that peripheral visual fields are represented in a ________ direction along the _________ ________ (_______ + ______ _____) |
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Definition
| The orderly map of the contralteral visual vield in the primary visual cortex is arranged so that peripheral visual fields are represented in a ROSTRAL direction along the CALCARINE FISSURE (CUNEUS + LINGUAL GYRUS) |
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Term
| The LGN is located at the termination of the ____ _____ in the _______ |
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Definition
| The LGN is located at the termination of the OPTIC TRACTS in the THALAMUS |
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Term
The LGN is composed of _#_ layers.
Layers #, #, # receive information from the contralateral hemifield
Layers #, #, # receive ipsilateral input |
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Definition
The LGN is composed of 6 layers.
Layers 1, 4, 6 receive information from the contralateral hemifield
Layers 2, 3, 5 receive ipsilateral input |
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Term
| Each LGN contains a representation of the ___________ visual hemifield |
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Definition
| Each LGN contains a representation of the CONTRALATERAL visual hemifield |
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Term
| The _#_ layers of the LGN are divided into _#_ groups; _#_ ____________ layers (1 + 2), _#_ _____________ layers (3-6) |
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Definition
| The 6 layers of the LGN are divided into 2 groups; 2 MAGNOCELLULAR layers (1 + 2), 4 PARVOCELLULAR layers (3-6) |
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Term
| Cells in the magnocellular layer are involed inperception of _______ + ______ contrast, __-cells |
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Definition
| Cells in the magnocellular layer are involed inperception of DARK + LIGHT contrast, M-cells |
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Term
| Cells in the parvocellular layers process fine ____ + _____ information, _-cells |
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Definition
| Cells in the parvocellular layers process fine SPATIAL + COLOR information, P-cells |
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Term
| In secondary pathways the retino-collicular projection travels through the _____ + terminates in the ________ ____ ____ of the ______ |
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Definition
| In secondary pathways the retino-collicular projection travels through the BSC + terminates in the SUPERFICIAL GRAY LAYERS of the COLLICULUS |
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Term
| Quadrant defects, first clue to some pathaolgoy in "____" ares of the _______, especially the _______ ______ cortex |
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Definition
| Quadrant defects, first clue to some pathaolgoy in "SILENT" ares of the CORTEX, especially the TEMPORAL LOBE cortex |
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Term
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Definition
| field defects which include everything except macular field |
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Term
| Macular sparing defects occur when entire _______ visual cortex is destroyed except for the _______ ______ |
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Definition
| Macular sparing defects occur when entire IPSILATERAL visual cortex is destroyed except for the OCCIPITAL POLE |
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Term
| Axons arising from post-synaptic cells in the subcortical visual nucli ascent through the _______ ______ to synapse with cells in the ______ _____ |
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Definition
| Axons arising from post-synaptic cells in the subcortical visual nucli ascent through the OPTIC RADIATIONS to synapse with cells in the VISUAL CORTEX |
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Term
| 2 Main areas of teh cortex that respond to visual stimulation |
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Definition
Primary visual (striate) cortex, AREA 17
Secondary + Tertiary visual (prestriate) cortex, AREA 18 + 19 |
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Term
| Primary visual cortex contains an orderly map of the ___________ visual hemifield, which it receives from neurons of the ___ |
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Definition
| Primary visual cortex contains an orderly map of the CONTRALATERAL visual hemifield, which it receives from neurons of the LGN |
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Term
| Primary visual cortex is arranged so that ventral visual field is represented in the ________ _____ of the ________ _______ |
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Definition
| Primary visual cortex is arranged so that ventral visual field is represented in the POSTERIOR POLE of the OCCIPITAL LOBE |
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Term
| Primary visual cortex, peripheral visual fields are represented in more ________ portions of the _________ ______ |
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Definition
| Primary visual cortex, peripheral visual fields are represented in more ANTERIOR portions of the CALCARINE SULCUS |
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Term
| Primary visual cortex, the foveal representation is greatly magnified and occupies a large portion of the ________ ______ |
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Definition
| Primary visual cortex, the foveal representation is greatly magnified and occupies a large portion of the CORTICAL TISSUE |
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Term
| Info in the primary visual cortex is then distributed through AREAS __ + __ (V_,V_), then to areas V_ in the _______ lobe for ______ __________ and to areas V_ in the ______ ________ lobe for perception of _______, _______ + _______, then to V_ in the ______-______ lobe for perception of ______ |
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Definition
| Info in the primary visual cortex is then distributed through AREAS 18 + 19 (V2,V3), then to areas V4 in the TEMPORAL lobe for OBJECT RECOGNITION and to areas V3 in the POSTERIOR PARIETAL lobe for perception of MOTION, ROTATION + DEPTH, then to V5 in the PARIETO-TEMPORAL lobe for perception of COLOR |
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