GA: Visual Tracts

Question 1

What is a visual field?

Answer 1

The area a person is able to see when both eyes are fixed in one postion

Question 2

What is the retinal field?

Answer 2

Location on the retina that an object in the visual field is projected.

Focused + centered on fovea centralis + macula lutea

Question 3

What zones make up the visual field?

Answer 3

Binocular zone (both eyes - central) + Monocular zone (R/L eye only)

Question 4

How is the retinal field subdivided?

*image is inverted on retina

Answer 4

Nasal + temporal retinal hemifields –> further divided into quadrants

Question 5

For example: the left half of the visual field forms an image of ___________.

Answer 5

The nasal (right) half of the left retina

The temporal (right) half of the right retina

Question 6

How do we describe visual deficits?

Answer 6

Based on the visual field

Question 7

What comprises the optic tract?

Answer 7

Nasal retina (contralateral eye)

Temporal retina (ipsilateral eye)

*they cross in optic chiasim*

Question 8

What do you need for depth perception?

Answer 8

Information from both retinas brought together

Question 9

How is the eye/optic tract organized?

Answer 9

In a retinotopic pattern

Question 10

Where does the optic tract terminate?

Answer 10

Lateral geniculate nucleus

Question 11

The magnocellular (M) layer =

Answer 11

input from rods + large receptive fields

sensitive to moving stimuli

Question 12

The parvocellular layer =

Answer 12

cones

small receptive field

Question 13

Ganglion cell axons that arise in the temporal retina:

terminate in _______ layers and are __________.

Answer 13

layers 2,3,5

IPSILATERAL

Question 14

Axons that arise in the nasal retina terminate in ________ layers and are ___________.

Answer 14

1,4,6

CONTRALATERAL

Question 15

The same point in visual space can be represented multiple times, why?

Answer 15

Cause the optic tract branches in multiple layers (6)

Question 16

Where does the geniculocalcarine pathway run (optic radiations)?

Answer 16

LGN –> Calcarine sulcus (primary visual cortex)

Question 17

Fibers from the lower quadrant of the contralateral hemifields (optic radiations) target _______.

Answer 17

Superior bank on cuneus

Question 18

Fibers from the upper quadrant of the contralateral hemifields (optic radiations) target _______.

Answer 18

Inferior bank on lingual gyrus

Question 19

Fibers that pass through Meyer loop come from where?

Answer 19

Upper quadrant of the contralateral hemifields (optic radiations)

Question 20

Fibers conveying information from the macula + fovea go to?

Answer 20

Caudal portions of the visual cortex

Question 21

Retinogeniculocalcarine pathway

Answer 21

Question 22

Because of Meyes loop, what can temporal lobe damage produce?

Answer 22

Sometimes a superior visual field deficit

Question 23

Objects in either half (L or R) of the visual field produce images upon the nasal hemiretina of the ips. eye + the temporal hemiretina of the cont. eye.

This is an example of?

Answer 23

Retinotopic Organization

Question 24

Where does the visual pathway end?

Answer 24

Brodmann’s area 17 (primary visual cortex/striate cortex)

Question 25

Areas 18,19, plus parts of the temporal + parietal lobes =

Answer 25

Visual Association cortex (parieto-occipito-temporal area)

Question 26

name these areas:

Answer 26

Question 27

What is the superior colliculus important for?

Answer 27

Directing eye movements

Question 28

What is the pretectal area important for?

Answer 28

Pupillary light reflex

Question 29

Review **pupillary constriction** reflex

Answer 29

Question 30

What is hemianopia?

Answer 30

Blindness in 1/2 of visual field

Question 31

What is quadrantanopia?

Answer 31

Blindness in one quadrant of the visual field

Question 32

What is homonymous visual fields?

Answer 32

Conditions in visual field losses are similar in both eyes

Question 33

What is heteronymous visual fields?

Answer 33

Conditions in which the two eyes have non-overlapping field losses (don't match)

Question 34

What is macular sparing?

Answer 34

Visual field loss that preserves vision in the center of the visual field

Question 35

An anterior lesion in the optic tract is more likely to be?

Answer 35

Incongruous (non symmetrical in both eyes)

Question 36

A lesion close to the visual cortex makes it likely to be?

Answer 36

Congruous (symmetrical in both eyes)

Question 37

Damage anterior to the optic chiasm affects:

Answer 37

Ipsilateral eye

Question 38

Damage @ the optic chiasm causes?

Answer 38

Heteronymous deficits

Question 39

Damage behind the optic chiasm causes:

Answer 39

Homonymous deficits

Question 40

What is associative visual agnosia?

Answer 40

Patient cannot name or describe an object in the visual field, BUT he can recognize + demonstrate its use