Visual Flashcards
What are the 3 cellular layers of the retina, in order that light goes through first.
- Ganglion cell layer
- Bipolar cell/interneuron layer
- Photoreceptors
Axons of what cells form the optic n.?
Ganglion cells (first AP)
Rods vs. cones-
Which has more photopigment per cell?
Rods (larger/taller)
Rods vs. cones-
Which has higher temporal resolution/faster response/shorter integration time?
Cones (less convergence in pw)
Rods vs. cones-
Which are saturated in daylight?
Rods
Rods vs. cones-
Which has more convergence on retinal pw’s?
Rods
Where in the retina is our best visual acuity?
Fovea (cones only)
Explain the entire visual pw from photoreceptor to cortex.
- Photoreceptor stimulates ganglion cell to send first AP.
- AP reaches optic n.
- Nasal portion of retinal nn. cross at optic chiasm, temporal portions do not. Optic tract is formed.
- Optic tract synapses at LGN of thalamus
- Optic radiations reach visual cortex
Rods vs. cones-
M-type ganglion cells are associated w/_____, P-type cells are associated w/_____.
Mr. PC
- Rods (respond best to Movement)
- Cones (respond best to color and fine details)
What is the Brodmann’s area # for the primary visual cortex?
What’s another name for it?
#17 - Striate cortex
Where are visual reflexes processed in the brainstem (not the cortex)?
*Pretectal area
Where are head and eye movements processed in the brainstem (not the cortex)?
[E.g. orienting reflex when something wiggles in our peripheral vision.]
*Superior colliculus
Regarding optic radiations, upper fibers run thru the _______________, lower fibers run thru the _______________.
- Parietal lobe
- Temporal lobe
How do lower fibers (of optic radiations) reach their path in the cortex?
Meyer’s loop
What physical/anatomical landmark runs deep to divide the occipital lobe at Brodmann’s area #17?
Calcarine fissure
What is the result of cutting the right optic n.?
Right eye blindness
Cutting the center of the optic chiasm only would lead to what?
Bitemporal hemianopia–loss of R field of R eye and L field of L eye
(besides cutting optic n., this is only result that effects both eyes differently)
What is the result of cutting the right optic tract or lesioning the right LGN?
Left homonymous hemianopia–loss of left field of both eyes
Right temporal lobe lesion would lead to what result?
“Pie in the sky” Left homonymous upper quadrantanopia–loss of pie slice on upper left of both eyes
Cutting of the right optic radiation would lead to what result?
Left homonymous lower quadrantanopia and macular sparing is often present–loss of most of left field of both eyes, sometimes center is spared
Lesion of the right visual cortex would lead to what result?
Left homonymous hemianopia with macular (fovea) sparing–loss of entire left field of both eyes w/center spared
After a deceleration injury, what is a common visual effect?
Loss of center of field only
What’s the name of the test that tests the optic n.?
What are the names of the 2 subtype reflexes?
What are we testing to confirm functionality?
- Pupillary light reflex
- If you shine a light in 1 eye, the response of the illuminated eye is the direct reflex, the response of the unilluminated eye is the consensual response.
- Testing both eyes confirms rostral midbrain is functional
What is the nucleus associated with the pupillary light reflex?
How come the reflex effects both eyes?
- Edinger-Westphal nucleus (EWN)
- Single optic n. splits at chiasm to supply both EWN’s.
