CNS FA17- Visual System Flashcards
Where are the lateral protrusions that form the optic cup?
The diencephalon
The ______ forms the retina?
Optic cup
The optic cup is connected to the diencephalon via
The optic stalk
The optic stalk becomes
Optic nerve
T/F: The retina and optic nerve are derived directly from diencephalon
True
Is the Optic nerve surrounded by CSF
Yes
What are the retinal cell types?
Astrick the main three
Photoreceptors *
Bipolar neurons *
Ganglion cells *
Horizontal cells
Amacrine cells
Which retinal cells types are a part of the neuron chain that converts light into recognizable images?
Photoreceptors —>
Bipolar neurons —>
Ganglion cells —>
Brain
Which are the retinal interneuron cells?
Horizontal
Amacrine
Which retinal cell receives the outside stimuli?
Photoreceptors
Type of photoreceptors that is Rod shaped and located at the periphery of the retinal.
They do not respond to light but respond to movement and Shapes and forms
Rods
Type of photoreceptors that is cone shaped, more numerous in the center of the retina and need light to work.
Stimulated by color
Cones
Retinal cells that are relay neurons that come in two types (atleast)
Bipolar neurons
Two types of bipolar neurons?
On-excite
Off-inhibit
Retinal cell type whose axons form the optic nerve.
It is considered projection neuron, output neurons and leaves the retina!
Ganglion
Where are the rods and cones located within the retina?
Outer nuclear layer
Outer synaptic/ outer plexiform layer is the location of which action in the visual chain?
Where Photoreceptors synapse with bipolar cells
Location of horizontal cells in the retinal?
Outer synaptic/plexiform layer
Ganglion cell location
Ganglion cell layer
Bipolar neurons (rod and Cone) and inter plexiform cell are located where in the retina?
Inner nuclear layer
What action occurs in the inner synaptic layer of the retina?
Bipolar synapses with ganglion cells
Amacrine cell location
Inner synaptic layer/plexiform
Function of the horizontal cells
Fine tuning of depth
Function of amacrine cells
Contrast enhancement
Motion detectors
How does light come into hit the rods and cones?
Optic nerve fiber layer —>
Ganglion cell layer —>
Inner plexiform layer —>
Inner nuclear layer —>
Outer plexiform layer —>
Outer nuclear layer —>
Rod and cone layer
Light travels through the many layer except at this point because the retinal cells other than the photoreceptors are pushed to the side and light directly hits it?
Fovea centralis
T/F: The fovea centralis is the center of the retina
True
From retina where does stimulus go?
Retina —> lateral geniculate body/nucleus in thalamus —> visual cortex
Optic tract splits into two strias.
This stria of the optic tract goes to lateral geniculate nucleus, then onto the cortex
Lateral stria
The optic tract splits into two strias:
This stria goes to the superior colliculus, pretectal area and suprachiasmatic nucleus
Medial stria
Function of superior colliculus in the visual pathway
Eye or head movement towards the stimulus
Pretectal area function in the visual pathway
Pupillary light reflex
Suprachiasmatic reflex (part of hypothalamus) function in visual pathway
Sleep/wake cycle
T/F: IT matters what you are looking at as it pertains to the superior colliculus function
False
T/F: Pretectal areas and suprachiasmatic nucleus focus of the amount of light coming in
True
Definition: Stimulus that is being seen from outside world
Visual field
Which stria of the optic tract split discerns what is being seen?
Lateral stria
Definition: How stimulus being seen hits the retina
Retinal field
Does the nasal retinal/ medial retinal field cross over? Where?
Crosses over at the optic chiasm
Does thelateral retinal field/temporal retinal field cross over?
No
Things that are temporal in the visual field hit which aspect of the retinal field as the pass through the lens?
Medial/nasal retinal field
Things that are central in the visual field hit which aspect of the retinal field as they pass through the lens?
The lateral/temporarily retinal field
Visual cortex is located
Occipital lobe surrounding calcarine sulcus
What are the six layers of the lateral geniculate nucleus?
4 are parvocellular neurons
2 are magnocellular (1st 2)
The first two layers of the lateral geniculate nucleus respond to
Movement
Form/shape
The remaining 4 layers of the lateral geniculate nucleus responds to
Color
Some shape and form
The two magnocellular layers of the lateral geniculate nucleus get their input from
Rods
The 4 parvocellular layers of the lateral geniculate nucleus receive input from
Cones
Which layers of the lateral geniculate nucleus receive contralateral input?
1
4
6
Layers of the lateral geniculate nucleus that receives ipsilateral input
2
3
5
The origin and insertion of the optic radiations in the visual pathway?
Lateral geniculate nucleus —> visual cortex
All of the lamina of the lateral geniculate nucleus go to which layer of the visual cortex?
Layer four of visual cortex
Layer four of the visual cortex receives all the input from lateral geniculate nucleus into organizing input in which way?
Ipsilateral
Contralateral
Neurons in lamina 4 project fibers where
Other layers of visual cortex
The upper three layer of the visual cortex (3,2,1) send the input where?
Extrastriate cortical region AKA association visual cortex
Layer 5 of the visual cortex sends the input where and what is its function?
Superior colliculus
Reinforce looking at stimulus, consciously
Slightly delayed
Function of associational visual cortex/ extrastriate cortical regions
Makes association between previous stimuli and new stimulus
Layer 6 of the visual cortex sends input where and what is its function?
To lateral geniculate nucleus
Negative reflex for negative feedback loop
Cut through optic nerve results in
Loss of vision in one eye
Total blindness of ipsilateral eye
Cut through the optic chiasm results in
Medial retinal field is lesioned so you can’t see what’s lateral in visual field
(Ispilateral nasal hemianpsia)
(Tunnel vision)
Cut through optic tract results in
Bitemporal heteronymous hemianopsia
Meyer loop
Contralateral fibers of optic tract that go into the temporal lobe
Cut through optic radiation closer to visual cortex results in
Contralateral homoymous hemianopsia with macular sparring
Why does macular sparing occur?
Receive information from fovea so it has a higher representation in the cortex
