Module D-07 Flashcards Preview

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Flashcards in Module D-07 Deck (41):
1

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

Nasal hemifield

2

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

Temporal hemifield

3

degree of upward visual field

50 degrees ( eyebrows obstruct view)

4

degree of downward visual field

80 degrees

5

Describe how the visual field gets projected onto the retina

- 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

6

4 locations where the projections of the retinal ganglion cells synapse

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

7

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

Lateral geniculate nucleus

8

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

trigger the circadian clock

9

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

part of the afferent limb of the pupillary light reflex

10

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

contribute to eye movements

11

What causes binocular vision?

the overlap of the visual fields of both eyes

12

________ retina fibers dont cross over

Temporal

13

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

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

14

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

Temporal; Inferior (to calcarine sulcus)

15

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

Parietal; superior ( to calcarine sulcus)

16

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

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

17

Brodmann's area for primary visual cortex

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

18

Blood supply of primary visual cortex

- 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).

19

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

retinotopic

20

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

closer to the occipital pole

21

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

closer to parieto-occipital sulcus

22

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

1)Ocular Dominance Columns
2)Orientation Columns

23

What are ocular dominance columns?

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).

24

What are Orientation columns?

Columns dedicated to orientation preference of the light source

25

How are the ocular dominance and orientation columns actually placed?

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.

26

What are parallel pathways of the retina?

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

27

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

magnocellular neurons (M ganglion cells)

28

Describe the pathway for Magnocellular neurons

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

29

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

parvocellular neurons (P ganglion cells)

30

Describe the pathway for Parvocellular neurons

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

31

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

Monocular blindness; Optic neuritis

32

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

Bitemporal hemianopia; Pituitary tumor

33

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

Homonymous hemianopia; Temporal lobe tumor

34

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

Homonymous superior quadrantic anopia; Temporal, or
occipital lobe tumor

35

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

Homonymous inferior quadrantic anopia ; Parietal, or occipital lobe tumor

36

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

Homonymous hemianopia; Posterior cerebral artery dysfunction

37

What type of lesions allow for macular sparing ?

vascular lesions involving the posterior cerebral artery or its branches

38

Why does macular sparing occur?

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

39

Color agnosia aka

Achromtopsia aka cortical color blindness

40

What is Achromatopsia?

Inability to distinguish colors or color hues

41

What causes Achromtopsia?

cortical lesions in areas 18 or 37