Module D-07

Question 1

half of the visual field for the eye that is towards the midline is called the

Answer 1

Nasal hemifield

Question 2

half of the visual field for the eye that is away form the midline is called the

Answer 2

Temporal hemifield

Question 3

degree of upward visual field

Answer 3

50 degrees ( eyebrows obstruct view)

Question 4

degree of downward visual field

Answer 4

80 degrees

Question 5

Describe how the visual field gets projected onto the retina

Answer 5

• The superior half of the visual field is projected to the inferior half of the retina, and vice versa.
• Nasal visual hemifield goes onto temporal retina and Temporal visual hemifield gis projected onto nasal retina

Question 6

4 locations where the projections of the retinal ganglion cells synapse

Answer 6

1) Lateral geniculate nucleus (thalamus)
2) Suprachiasmatic nucleus (hypothalamus)
3) Pretectal nucleus (midbrain)
4) Superior colliculus (midbrain)

Question 7

Which nucleus is relay station between the retina and the primary visual cortex?

Answer 7

Lateral geniculate nucleus

Question 8

What is the purpose of the fibers of retinal ganglion cells that terminate in the suprachiasmatic nucleus?

Answer 8

trigger the circadian clock

Question 9

What is the purpose of the fibers of retinal ganglion cells that terminate in the Pretectal nucleus?

Answer 9

part of the afferent limb of the pupillary light reflex

Question 10

What is the purpose of the fibers of retinal ganglion cells that terminate in the Superior colliculus?

Answer 10

contribute to eye movements

Question 11

What causes binocular vision?

Answer 11

the overlap of the visual fields of both eyes

Question 12

________ retina fibers dont cross over

Answer 12

Temporal

Question 13

Describe pathway of light seen in left superior quadrant of both eyes

Answer 13

1) Right eye: light is in nasal superior hemifield and projects
onto temporal inferior hemiretina
temporal fibers follow optic nerve=> optic
chiasm (no crossing over) => optic tract =>
synapse in right lateral geniculate nucleus =>
=> temporal radiation fibers of LGN => synapse
in inferior portion of Primary visual cortex
2) Left eye: light in temporal superior hemifield and projects
onto nasal inferior hemiretina
nasal fibers follow optic nerve=> optic
chiasm (CROSSOVER) => optic tract
(contralateral side)=> synapse in right lateral
geniculate nucleus => temporal radiationfibers
of LGN => synapse in inferior portion of Primary
visual cortex

Question 14

Fibers of the LGN that carry info of superior visual field follow __________ radiation pathway and end up in _________ part of primary visual cortex

Answer 14

Temporal; Inferior (to calcarine sulcus)

Question 15

Fibers of the LGN that carry info of inferior visual field follow __________ radiation pathway and end up in _________ part of primary visual cortex

Answer 15

Parietal; superior ( to calcarine sulcus)

Question 16

Describe pathway of light seen in left inferior quadrant of both eyes

Answer 16

1) Right eye: light is in nasal inferior hemifield and projects
onto temporal superior hemiretina
temporal fibers follow optic nerve=> optic
chiasm (no crossing over) => optic tract =>
synapse in right lateral geniculate nucleus =>
=> parietal radiation fibers of LGN => synapse
in superior portion of Primary visual cortex
2) Left eye: light in temporal inferior hemifield and projects
onto nasal superior hemiretina nasal fibers
follow optic nerve=> optic chiasm
(CROSSOVER)
=> optic tract (contralateral side)=> synapse in
right lateral geniculate nucleus => parietal
radiation fibers of LGN => synapse in superior
portion of Primary visual cortex

Question 17

Brodmann’s area for primary visual cortex

Answer 17

Area 17 , around the occipital pole mainly on medial side of the brain

Question 18

Blood supply of primary visual cortex

Answer 18

• major blood supply from calcarine branches originating from the posterior cerebral artery.
• small portion of the primary visual cortex located around the occipital pole, may also receive blood supply from the middle cerebral artery (especially after an occlusion of the
  posterior cerebral artery).

Question 19

The topographical organization of the primary visual cortex is called “_________” map

Answer 19

retinotopic

Question 20

Where on the primary visual cortex would the macular region of vision be located?

Answer 20

closer to the occipital pole

Question 21

Where on the primary visual cortex would the peripheral region of vision be located?

Answer 21

closer to parieto-occipital sulcus

Question 22

What are the two types of columns in Primary visual cortex?

Answer 22

1) Ocular Dominance Columns

2) Orientation Columns

Question 23

What are ocular dominance columns?

Answer 23

areas (columns) dedicated to input from one eye, for example the ipsilateral eye (I), which lie next to areas (columns) dedicated to input from the contralateral eye (C).

Question 24

What are Orientation columns?

Answer 24

Columns dedicated to orientation preference of the light source

Question 25

How are the ocular dominance and orientation columns actually placed?

Answer 25

Neurons within the primary visual cortex are characterized by their preference for input from either the ipsilateral or contralateral eye, as well as by their preference for a certain orientation of a bar of light.

Question 26

What are parallel pathways of the retina?

Answer 26

parallel pathways which follow the same anatomical structures are specialized for certain aspects of visual information, which are depth, motion, form and color.

Question 27

The pathway for depth and motion starts with | ____________ in the retina.

Answer 27

magnocellular neurons (M ganglion cells)

Question 28

Describe the pathway for Magnocellular neurons

Answer 28

synapse in 2 of the 6 layers of the LGN, then to the primary visual cortex and then follow the parietal (dorsal) pathway

Question 29

The pathway for form and color starts with __________ in the retina

Answer 29

parvocellular neurons (P ganglion cells)

Question 30

Describe the pathway for Parvocellular neurons

Answer 30

Synapse in the other 4 of the 6 layers of the LGN , then to the primary visual cortex and then follow the inferior temporal (ventral ) Pathway

Question 31

If there is a lesion in the Optic nerve then the visual field defect is _________ and the lesion origin is ___________

Answer 31

Monocular blindness; Optic neuritis

Question 32

If there is a lesion in the Optic chiasm then the visual field defect is _________ and the lesion origin is ___________

Answer 32

Bitemporal hemianopia; Pituitary tumor

Question 33

If there is a lesion in the Optic tract then the visual field defect is _________ and the lesion origin is ___________

Answer 33

Homonymous hemianopia; Temporal lobe tumor

Question 34

If there is a lesion in the temporal radiation( Meyer's loop) then the visual field defect is _________ and the lesion origin is ___________

Answer 34

Homonymous superior quadrantic anopia; Temporal, or | occipital lobe tumor

Question 35

If there is a lesion in the Parietal radiation then the visual field defect is _________ and the lesion origin is ___________

Answer 35

Homonymous inferior quadrantic anopia ; Parietal, or occipital lobe tumor

Question 36

If there is a lesion in the visual cortex then the visual field defect is _________ and the lesion origin is ___________

Answer 36

Homonymous hemianopia; Posterior cerebral artery dysfunction

Question 37

What type of lesions allow for macular sparing ?

Answer 37

vascular lesions involving the posterior cerebral artery or its branches

Question 38

Why does macular sparing occur?

Answer 38

the blood supply of the occipital pole of the cerebral cortex, which is the area representing macular vision, may stay intact, due to sufficient blood flow originating from the middle cerebral artery

Question 39

Color agnosia aka

Answer 39

Achromtopsia aka cortical color blindness

Question 40

What is Achromatopsia?

Answer 40

Inability to distinguish colors or color hues

Question 41

What causes Achromtopsia?

Answer 41

cortical lesions in areas 18 or 37