Lecture 3- Vision Sensation

Question 1

optic chiasm

Answer 1

where half the ganglion cells in the optic nerve cross over to the other side of the brain
(light from the RIGHT visual field enters the pupil from such an angle that it actually hits the LEFT side of the retina & vice versa

Question 2

thalamus

Answer 2

relay centre(s) of the brain. Most sense-related info passes through it. Cross-modal processing begins

Question 3

lateral geniculate nucleus (LGN)

Answer 3

Receives info from both eyes in a “retinotopic” fashion- cells in the LGN have a map-like correspondence to cells in the retina
- filter for irrelevant info

Question 4

Topographic mapping

Answer 4

right LGN processes info from the left visual field and vice versa

Question 5

hemianopia

Answer 5

blindness to parts of the visual field (wedge-shaped, hourglass)- caused by LGN damage

Question 6

superior colliculus

Answer 6

has connections between info coming from each eye. allows for richer and more complex processing of info

Question 7

primary visual cortex/ striate cortex

Answer 7

striated/ striped, damage = blind

Question 8

cortical magnification

Answer 8

distortion of the visual field

Question 9

extrastriate cortex

Answer 9

region of the cortex bordering the primary visual cortex and containing multiple areas involved in visual processing

Question 10

heteronomous

Answer 10

different sides

Question 11

homonymous

Answer 11

same sides

Question 12

Area V2

Answer 12

receives input from V1 & outputs to V3, V4, V5
- most neurons in this area tuned to simple visual characteristics: orientation, spatial frequency, size, colour, shape

Question 13

Area V3

Answer 13

implicated in the process of global motion

Question 14

“what” pathway

Answer 14

names & functions of objects, regardless of location
- areas V1, V2, V3 provide info to V4, which passes to V5 and other areas

Question 15

Cerebral achromatopsia

Answer 15

cannot perceive colour, caused by damage to “what” pathway

Question 16

“where” pathway

Answer 16

locations and shapes of objects but not names and functions
- Areas V1, V2, V3, V4 provide info to area V5

Question 17

akinetopsia

Answer 17

motion perception is disrupted
- caused by damage to “where” pathway

Question 18

Inferotemporal (IT) cortex

Answer 18

beneath the temporal cortex
- neurons in this part of brain sensitive to more complicated info patterns
- chairs, buildings, tools, words

Question 19

apperceptive agnosias

Answer 19

failures of perception. cannot form stable representations of objects
- fail “unusual views/incomplete figure” tests

Question 20

Associative agnosias

Answer 20

people can form “percepts” of objects but cannot identify the specific category to which the object belongs (prosopagnosia)

Question 21

photoreceptors

Answer 21

horizontal cells synapse between adjacent photoreceptors and bipolar cells
- allows lateral inhibition

Question 22

bipolar cells

Answer 22

amacrine cells synapse between adjacent bipolar and retinal ganglion cells
- amacrine cells involved in the processing of contrast and measuring the timing of visual inputs

Question 23

retinal ganglion cells

Answer 23

• leave the eye via the optic nerve
• info from 2 eyes may cross at the optic chiasm

Question 24

Lateral Geniculate Nucleus

Answer 24

Signals from many senses are relayed through, before going onto parts of cortex that process in more detail

Question 25

striate cortex:

Answer 25

back of the brain, occipital lobe

Question 26

simple cells

Answer 26

• respond to orientation of lines and edges
• change of orientation as little as 15 degrees will cause cells to stop responding

Question 27

monocular

Answer 27

respond only to one eye