Visual Pathways And Eye Movements Flashcards
Axons of ganglion cells and axons of higher order cells on which they synapse form the ____; they relay into to the primary visual cortex via the _____.
This pathway has a precise _____ arrangement of fibers.
Visual pathway
Thalamus
Retinotopic
____ is the area a person is able to see when both eyes are fixed in one position.
Light passes from objects in the visual field, through the pupil to an image upon the retina creating a _____.
Object are focused and centered at the location of the ____ and _____.
Medial to the macula is the _____ where the retinal axons leave the eyes as the optic N.
Visual field
Retinal field
Fovea centralis and macula lutea
Optic disc: photoreceptors are absent from this region creating a blind spot
Visual fields are divided into two zones?
_____ is the location on the retina that an object in the visuals fiend is projected upon.
What are the retinal hemifields?
Binocular zone: brad central region seen by both eyes
Monocular zone: seen only by corresponding eye
Retinal field: nasal, temporal -> upper, lower
The image on the retina is _____ in both lateral and vertical dimensions.
The L half of the visual field forms an image _____.
The R half of the visual field forms an image ____.
Inverted
On the nasal (R) half of the L retina and the temporal (R) half of the R retina
On the nasal (L) half of the R retina and the temporal (L) half of the L retina
Two optic N decussation in the _____.
The nasal half of each retina goes to the _____ optic tract. The temporal half of each retina goes to the ____ optic tract.
What does the optic tract contain?
Bringing info from the contralateral visual field, brings together info from comparable areas of the retinas, allowing for ____.
Otic chiasm
Contralateral;ipsilateral
Fibers from the temporal (ipsilateral eye) plus fibers from the nasal retina (contralateral eye)
Depth perception
The optic tract curves around the cerebral peduncle and terminate in the _____ in a ____ pattern.
The ventral base of the nucleus is formed from _____.
The dorsal and lateral borders are formed by the _____.
Lateral geniculate nucleus; retinotopic
Incoming optic tract (retinogeniculate) fibers
Outgoing optic radiations
The LGN (lateral geniculate nucleus) is divided into ____ and ____ layers.
Together, these layers are divided into 6 layers of the LGN that run ____.
The pattern is the same in each layer allowing for what?
Magnocellular
Parvocellular
Midline to periphery; rostral to caudal
A given point in the visual field is represented by a column of cells extending through all six layers -> therefore the same point in the visual field is represented 6 times -> allowing for greater acuity
The magnocellular layer of the LGN includes what two layers?
It contains ____ cells. It receives ganglion cell inputs relayed from ___.
This layer also has a ____ the receptive field, thick and rapidly conducting axons and is sensitive to ____.
Layers 1 & 2
Large; rods
Larger; moving stimuli
The parvocellular layer of the LGN contains includes what two layers?
It contains ____ cells. It receives ganglion cell inputs relayed from ___.
This layer also has a ____ the receptive field, slower conducting axons and topically responsive to ____.
Layers 3-6
Small; cones
Small; stationary stimuli and high-acuity color vision
Ganglion cells arising from the temporal retina remain ____ and terminate in layers ____ of the _____ LGN.
Axons arising in the nasal retina ____ and terminate in layers ____ of the ____ LGN.
Uncrossed; 2,3,5; ipsilateral
Cross; 1,4,6; contralateral
Secondary neurons from the LGN extend a large bundle of myelinated fibers called the ____.
They relay info to the primary visual cortex located on the upper and lower banks of the ____. This pathway is also called ____.
Optic radiation
Calcarine sulcus
Geniculostriate or geniculocalcarine pathway
Fibers in the lower quadrants of the visual fields target the _____ of the calcarine sulcus in the visual cortex.
Fibers in the upper quadrant of the visual field target form the ____ in the temporal lobe then target the ___ of the calcarine sulcus in the visual cortex.
Fibers conveying info from the macula and fovea originate in the central LGN and pass to ____.
Superior bank (cuneus)
Meyer loop; inferior bank (lingual gyrus)
Caudal portions of the visual cortex
The macula is represented posteriorly in the region of the ____.
Occipital pole
The primary visual cortex is also called the ____ because there are numerous myelinated fibers within a discrete layer.
The calcarine sulcus lies in Brodmann’s area ____.
Striate cortex
17
The striate cortex is surrounded by Brodmann’s area ____ and ____.
These areas and related parts of the parietal-occipito-temporal area comprise the _____. This is also interconnected with area ____.
18 and 19
Visual association cortex; 17
Some fibers of the optic tract will send fibers to ____ and ____.
Superior colliculus and pretectal/pretectum areas
The superior colliculus directs ____ and _____.
It has retinal input from the _____ that bypass the LGN.
Receives cortical input from ____.
Also receives input from ____ and ____.
Head movements and visual reflexes
Optic tract
Area 17
Spinotectal and auditory
The pretectal/pretectum area is a _____ located _____.
It receive inputs from ____ and _____.
These nuclei respond to ____.
Bilateral group of interconnected nuclei near the midbrain-forebrain junction
Bilateral fibers from the optic tract and LGN and suprachiasmatic nucleus
Light -> non-conscious behavioral responses to changes in light (pupillary light reflexes)
Voluntary eye movements are controlled by the ____ in the posterior portion of the ____.
____ fibers descend into the superior colliculus and control the LMN of CN III, IV, VI (conscious eye movements)
Frontal eye fields; middle frontal gyrus
Corticotectal
Occipital eye fields are in the visual association cortex and project ____ to the _____.
It controls ____ eye movements.
Corticotectal fibers; superior colliculus
Unconscious
Blindness in one-half of the visual field.
Blindness of a quadrant of the visual field.
Conditions in visual field losses are similar in both eyes
Conditions in which the two eyes have non-overlapping field losses
Hemianopia
Quadrantanopia
Homonymous visual fields
Heteronymous visual fields
A _____ lesion is when the visual field loss of one eye can be superimposed on that of the other eye…they are symmetrical.
The closer the lesion is the the visual cortex the more _____ it will be.
The more anterior the lesion is in the optic tract, the more likely it will be ____.
Congruous
Congruous
Incongruous
Damage anterior to the chiasm affects only the ____ eye.
Damage at the chiasm causes _____ deficits.
Damage behind the chiasm causes ____ deficits.
Ipsilateral
Heteronymous
Homonymous
A destruction of one optic N causes blindness in the eye that it arises
Damage to one side of the optic chiasm destroys noncrossing ipsilateral fibers
Damage to the crossing fibers from both eyes at the optic chiasm
Destruction of one optic tract
Damage to one temporal lobe and parts of optic radiation
Damage to one occipital lobe but the macular representation is large so macular sparing
Monocular blindness
Nasal hemianopia
Bitemporal hemianopia
Contralateral homonymous hemianopia
Contralateral homonymous superior quadrantopia
Contralateral homonymous hemianopia with macular sparing
____ is due to an infraction in the L occipital lobe and posterior corpus callosum.
What causes this?
What are the symptoms?
Associative visual agnosia
Secondary occlusion of the posterior cerebral A
Disconnects the language area from the visual association cortex -> pt cannot name or describe an object in the visual field but can recognize and demonstrate its use
