Visual Systems

Question 1

How is the retina dividd into quadrants?

Answer 1

nasal and temporal hemiretinas, then upper and lower: 4 quadrants

Question 2

What order neurons are the ganglion cells?

Answer 2

third order - but they synapse on the LGN of the thalamus - making it different from the somatosensory pathways

Question 3

Are damages to the visual pathway usually rnamed accoridng to the affected visual field or retinalf ield?

Answer 3

visual

Question 4

What is a hallmark of binocular visual field?

Answer 4

both eyes contribute to each visual field - this is why having the fields go to the contralateral cortex is important

Question 5

THe nasal retina gets information from the ___ field

Answer 5

the temporal field!

Question 6

So nerves carrying information about the ___ field from the ____ retina will cross as the optic chiasm

Answer 6

nerves carrying information form the temporal field at the nasal retina will cross at the chiasm

Question 7

WHy is the location of the optic chiasm clinically significant?

Answer 7

it’s located just anterior to the pituitary gland, so pituitary tumors will compress the chiasm, creating a loss of TEMPORAL FIELDS!

Question 8

What part of the retina receives information from the upper visual field?

Answer 8

the lower half of the retina

Question 9

What is the difference between homonymous and heteronymous damage?

Answer 9

homonymous = defects involve one visual field

heteronymous = defects involve parts of both visual fields, so defects are non-overlapping = these occur at the chiasm!

Question 10

Where do most axons from the retinal ganglion cells terminate?

Answer 10

the lateral geniculate nucleus

Question 11

Each LGN receives information from only one _____

Answer 11

visual field (contralateral)

Question 12

Each LGN is divided into 6 layers, each receiving information from only one____

Answer 12

eye

Question 13

Describe the retinotopic mapping of theLGN

Answer 13

THe medial half of the LPN is from the lower visual field while the lateral half is form the upper visual field

The central 2/3 of the LGN are devoted to the macula, then it’s to the nasal retinal, then the otuer portion is to the temporal retina

Question 14

What are the three other locations axons can project to besides the LGN? FOr what purpose?

Answer 14

1. reticular fibers of hypothalamus = regulation of circadian rhythm
2. Pretectum = reflexive control of pupils and lens
3. Superior colliculus = orienting movements of head and eyes

Question 15

What is another term for the optic radiation?

Answer 15

geniculocalcarine tract

Question 16

What are the two pathways within the geniculocalcarine tract and what info do they carry?

Answer 16

sublenticular = fibers from the upper visual field travel through the temporal lobe as meye’rs loop

retrolenticular = fibers from lower visual field travel direclty thorugh the parietal lobe to the occipital cortex

Question 17

If you damage meyer’s loop, you lose vision in the ___ visual field of the contralateral field.

Answer 17

upper

Question 18

THe primary visual cortex surrounds the ___ fissure separating what two gyri?

Answer 18

the calcarine fissue between the lingual gyri (bottom) and the cuneate gyri (top)

Question 19

The upper visual field projects to the ___ gyrus

the lower visual field projects to the ___ gyrus

Answer 19

upper visual field = lingual gyri (lower one)

lower visual field = cuneate gyri (upper one)

Question 20

Where in the primary visual cortex is macular representation?

Answer 20

the most caudal 1/3 of the area is for the macula, while the peripheral fields get the most rostral 2/3 (temporal most rostral, nasal in the middle)

Question 21

what types of information are responded to in the primary visual cortex?

Answer 21

color

location

shape and motion

Question 22

Stroke to the visual cortex will result in contralateral field loss, with what special feature?

Answer 22

macular sparing

Question 23

What sorts of visual information does the visual association cortex deal with?

Answer 23

complexity of vision like object recognition, hand-eye coorination, eye movements, etc.

Question 24

What are the two association cortex projection streams?

Answer 24

dorsal stream and ventral stream

dorsal = to the parietal and upper temporal = the “where” (location, movement, position)

ventral = projections to inferior temporal cortex= “what” (form, color, oject recognition, memroy)