Exam 4: Visual system pathways- Michaels

Question 1

Describe the general visual pathway

Answer 1

1)Retinal ganglion cells found at the back of the eye pick up information. 2)send down the optic nerve, cross at the optic chiasm. 3)Go down the optic tract to Lateral Geniculate Nucleus. 4) Follow Optic radiation to visual cortex in occipital lobe

Question 2

What are the names of the two hemiretinas?

Answer 2

Nasal and Temporal

Question 3

What makes up the optic nerve?

Answer 3

Axons from the retinal ganglion cells

Question 4

What order nerve are ganglion cells and where do they synapse?

Answer 4

Third order; most will synapse in lateral geniculate nucleus

Question 5

Define monocular visual field

Answer 5

what is seen through one eye when the other is covered

Question 6

Define binocular visual field

Answer 6

includes the monocular field of each eye

Question 7

Where does information from the left visual field project to?

Answer 7

Contralaterally; projects to right thalamus and cortex

Question 8

What can happen when there is a lesion near the pituitary gland?

Answer 8

Can disrupt the optic chiasm because they are so closely related; will affect the nasal hemiretina (temporal field) of both eyes

Question 9

What axon of fields crosses at the optic chiasm?

Answer 9

Nasal fields

Question 10

Define a homonymous lesion of the optic tract and what will result

Answer 10

Defects in one visual field/eye because the optic tract contains all the neurons for input from both eyes (will lose entire RIGHT VISUAL FIELD if there’s a lesion at the left optic tract).

Question 11

Define heteronymous damage and where it could occur

Answer 11

Defects in parts of both visual fields and defects are not overlapping- occurs at the chiasm

Question 12

Where do lateral geniculate nuclei receive input?

Answer 12

only one contralateral visual field

Question 13

Describe the mapping of the lateral geniculate nucleus

Answer 13

Split in half with lower visual field medial to the upper visual field. From lateral to medial in the lower visual field, the map is: Macula (overrepresented), binocular, monocular.

Question 14

How does the lower visual field travel to the cortex from the lateral geniculate nucleus

Answer 14

retrolenticular tract (through parietal lobe)

Question 15

How does the upper visual field travel to the cortex from the lateral geniculate nucleus?

Answer 15

Via sublenticular tract through meyers loops (temproal lobe)

Question 16

Describe the gyri that are superior and inferior to calcarine fissure in the olfactory lobe

Answer 16

Lingual gyrus (upper visual fields) is inferior to the calcarine fissure. Cuneate gyrus (lower visual fields) is superior to the calcarine fissure

Question 17

How are the gyri around the calcarine fissure mapped posteriorly to anteriorly?

Answer 17

Posterior to anterior: Macular, binocular, monocular vision

Question 18

Where is the visual association cortex located

Answer 18

Areas 18 and 19

Question 19

What does the visual assocation cortex do?

Answer 19

deals with complexity of vision (object recognition and significance, hand-eye coordination, eye movements)

Question 20

Where does dorsal stream of the visual association cortex project to? What information does it deal with?

Answer 20

projects to parietal and upper temporal cortex; info about the “where” of the visual stimulus (location, movement, position in space)

Question 21

Where does the ventral stream of the visual association cortex project to? What information does it handle?

Answer 21

Projects to inferior temporal cortex; info about “what of a stimulus (form, color, object recognition, memory)

Question 22

What order neuron are cells that have their cell bodies in the lateral geniculate nucleus and project to the occipital lobe?

Answer 22

4th order