Class_02_Vision

Question 1

Retina

Answer 1

Contains many photosensitive cells at the back of the eye
- produce electrical activity when stimulated

Question 2

Optic nerve

Answer 2

• Receive electrical signal from retina
• Transfer them to occipital lobe

Question 3

Adaption

Answer 3

• The light has to pass through lots of other cells first
• They adapt to anything that stays still and then They stop firing

Question 4

Fovea

Answer 4

This is the only part of the retina which allows high-definition vision
- can only see things in detail that are focused on the fovea

Question 5

Macula

Answer 5

a larger area than the fovea and contains other parts, not just the fovea
- used interchangeably with fovea

Question 6

Blind Spot

Answer 6

• Where the axons all meet to leave the retina
• forming the optic nerve
• no light receptors
• blind in that part
• very rarely aware of that blind spot

Question 7

Rod Cells

Answer 7

• Only sensitive to intensity of light
• sensitive to low levels of light
• monochrome

Question 8

Cone Cells

Answer 8

• Sensitive to particular wavelengths of light
• RGB
• require more stimulation than rod cells

Question 9

Visual Pathway

Answer 9

Retina -> Optic nerves -> Optic chiasm -> Optic tracts -> Lateral geniculate nucleus (LGN) of Thalamus -> Visual cortex

Question 10

Optic Chiasm

Answer 10

Carrying the information from the retina
- split up optic nerves
- some staying on the same side of the body
- some crossing over to the opposite side

Question 11

Left Visual Field of Both Eyes

Answer 11

Right retina -> Optic nerves -> Optic Chiasm -> Right optic tract -> Right lateral geniculate nucleus (LGN) of Thalamus => Right visual cortex

Question 12

Right Visual Field of Both Eyes

Answer 12

Left retina -> Optic nerves -> Optic Chiasm -> Left optic tract -> Left lateral geniculate nucleus (LGN) of Thalamus => Left visual cortex

Question 13

Optic Radiations

Answer 13

3 different routes that projections take from the LGN to the primary visual cortex
- Meyer’s loop
- Central bundle
- Dorsal bundle

Question 14

Meyer’s loop

Answer 14

Upper visual field travel through
the temporal lobe

Question 15

Central Bundle

Answer 15

Middle visual field travel through
the parietal lobe

Question 16

Dorsal Bundle

Answer 16

Lower visual field travel through
the parietal lobe

Question 17

The most serious brain damage causing visual field loss

Answer 17

• Damage all of the radiations on one side of the brain
• Damage the primary visual cortex in the occipital lobe

Question 18

Hemianopia

Answer 18

A half blind
- a substantial loss of vision for the RIGHT visual field (of each eye)
- damage to the LEFT hemisphere optic radiations
- damage to the LEFT primary visual cortex
- Vice versa: LEFT visual field from RIGHT parts of the brain

Question 19

Quadrantanopia

Answer 19

Quarter blind
- loss of vision for an upper/lower part of visual field (seen from either eye)
- damage to one of optic radiation

Question 20

Upper Left Quadrantanopia

Answer 20

loss of vision to the upper left visual field (seen from either eye)
- damage to right hemisphere Meyer’s loop

Question 21

Homonymous Hemianopia

Answer 21

same hemianopia for both eyes

Question 22

Macula Sparing

Answer 22

with hemianopia
- maintain vision within the part of the visual field supplied by information from the macula of the retina
- receiving blood supply from both the posterior cerebral artery
and the middle cerebral artery

Question 23

scotoma

Answer 23

smaller visual field losses often occur, so that an area of visual field much smaller than a quadrant
- will shrink with recovery
- human all have a scotoma in each eye, caused by the blind spot

Question 24

Superior Colliculi

Answer 24

Receive projections from the retina
- attention
- eye movements towards things that we see

Question 25

Visual Field Check

Answer 25

2 finger signal at each eye quadrant

Question 26

Case Bryan Kolb

Answer 26

Left homonymous hemianopia - Right primary visual cortex damage

Question 27

Event Awareness

Answer 27

Accurately guess about things presented to their blind fields

Question 28

Case G.Y.

Answer 28

Right homonymous hemianopia with macular sparing - Left occipital lobe damage - able to describe the direction of lights moving within blind hemifield - Reason: processing some visual information in earlier stages in subcortical regions - LGN and visual areas of thalamus is still intact

Question 29

Blindsight

Answer 29

- cortically blind - can perform visual tasks - no visual consciousness

Question 30

Circadian Rhythms

Answer 30

- sleep-wake cycle - changes in immunity responses - body temperature and appetite

Question 31

Suprachiasmatic Nucleus

Answer 31

Receiving light information from the retina or ipRGCs - Allow the circadian rhythms

Question 32

Intrinsically Photosensitive Retinal Ganglion Cells (ipRGCs)

Answer 32

Special light sensitive neuron - not rod or cone cell

Question 33

Circadian rhythms implications for cognitive assessment

Answer 33

Attention and working memory appear to be most efficient in the afternoon - neurodegenerative disease caused cognitive disorders

Question 34

Color blindness

Answer 34

- proteins that produce sensitivity to light are on the X chromosome - color blindness is relatively rare in women

Question 35

Ishihara Test

Answer 35

Color blindness test - numbers in plates

Question 36

Cerebral Achromatopsia

Answer 36

Damage to the ventral occipital cortex - can be unilateral brain damage - one side color, one side color blinded quadrant visual field achromatopsia

Question 37

Developmental Dyslexia

Answer 37

1. Phonological processing impairments 2. Visual processing problems - have LGN that are smaller -> affect magnocellular regions

Question 38

Dyslexia Assessment

Answer 38

Reading aloud or repeating pseudowords - e.g. ‘polatile’ or ‘dovine’ - rely on phonological skills

Question 39

Magnocellular

Answer 39

‘Big cells’ - ganglion cell that carry information from the retina to the lateral geniculate nucleus (LGN), via the optic nerve - small LGN -> affect magnocellular -> dyslexia - dorsal visual stream - connect the LGN to the primary visual cortex to the parietal lobe

Question 40

Dorsal Visual Stream

Answer 40

Retina -> primary visual cortex -> parietal lobe - convey information used for attention, and motion, and timing

Question 41

Magnocellular System Input

Answer 41

Red and green cone cells in the retina

Question 42

Treatment for dyslexia

Answer 42

1. Yellow filter glasses -> stimulate magnocellular system 2. Blue filter glasses -> stimulate ipRGCs -> suprachiasmatic nucleus -> circadian rhythms - blue color of sky in daytime