Ch. 13

Question 1

Area V1 of the visual cortex is sometimes also called the ______ cortex?

Answer 1

Striate cortex -> due to distinct layers

Question 2

What are blob & interblob regions responsible for, respectively?

Answer 2

Blob (cytochrome rich areas) -> color perception; Interblob -> form & motion perception

Question 3

Which two areas of the visual cortex are functionally heterogeneous?

Answer 3

V1 & V2

Question 4

After V2, what are the three distinct parallel pathways that emerge on route to the parietal & temporal cortices?

Answer 4

Dorsal stream, Superior Temporal Sulcus stream (STS), Ventral stream

Question 5

What is the main difference between the dorsal, STS, and ventral streams?

Answer 5

Dorsal -> movement perception; Ventral & STS -> object & color perception, & certain movements

Question 6

What is one interesting effect that can occur from V1 damage?

Answer 6

Patients appear completely blind, yet some information is sent to other processing areas; ex. patient unable to see, but somewhat able to respond to visual information

Question 7

What is the main role of area V1?

Answer 7

Form, Color, & Motion perception -> information then sent to all other higher processing areas

Question 8

What is the main role of area V2?

Answer 8

Form, Color, & Motion perception -> information then sent to all other higher processing areas

Question 9

What is the main role of area V3?

Answer 9

Specialized in dynamic form; shape of objects in motion; form analysis

Question 10

What is the main role of area V4?

Answer 10

Mainly color information processing, & some form perception

Question 11

What is the main role of area V5?

Answer 11

Motion perception specialization

Question 12

What is another name for area V5?

Answer 12

The middle temporal area/area MT

Question 13

What is “vision for action” processing and what stream is responsible for it?

Answer 13

Visual processing required to direct specific movements (ex. reaching for an object) -> parietal lobe in dorsal stream

Question 14

What is “action for vision” processing?

Answer 14

Searching/scanning for some part of a target object to attend it selectively

Question 15

What are the two kinds of “visual space” processing? (Hint: _____centric & _____centric)

Answer 15

Egocentric space -> objects have a location relative to the individual; Allocentric space -> objects have a location relative to one another

Question 16

What does “visual attention” processing mean?

Answer 16

Neurons in cortex have many attentional mechanisms; may respond selectively to certain stimuli

Question 17

What did David Milner & Melvyn Goodale propose?

Answer 17

They proposed that the dorsal stream is a set of systems for visual control of action

Question 18

What 3 findings were Milner & Goodale’s proposal about the function of the dorsal stream based on?

Answer 18

1) Visual neurons in PPC are only active when the brain is acting on visual information; 2) Visual neurons in PPC act as an interface between analysis of visual world & action taken on it; 3) Most visual impairments due to lesions in PC are visuomotor/visuospatial

Question 19

What are polysensory neurons and which of the three visual processing streams are they associated with?

Answer 19

Polysensory neurons -> respond to visual & auditory input, or visual & somatosensory input; found in the STS stream

Question 20

What is the proposed function of the STS stream?

Answer 20

Perception of biological motion; i.e., actions of others & visuospatial relation among elements in a scene

Question 21

What are the two key ways that the brain & eyes organize visual fields?

Answer 21

1) Left half of each retina sends projections to left side of the brain; vice versa for right halves, 2) Different parts of the visual field are topographically represented in different areas of V1

Question 22

What is monocular blindness?

Answer 22

Complete blindness in one eye only

Question 23

What is bitemporal hemianopia?

Answer 23

Loss of vision in both temporal fields

Question 24

What is right nasal hemianopia?

Answer 24

Loss of vision in one nasal field

Question 25

What is homonymous hemianopia?

Answer 25

Blindness of one entire visual field (i.e., left field of both eyes; NOT blindness of both eyes as a whole)

Question 26

What is quadratanopia?

Answer 26

Blindness in only one quadrant of the visual field (ex. top left quadrant in both eyes)

Question 27

What is macular sparing?

Answer 27

The central visual field is not lost despite entire temporal or nasal fields being lost

Question 28

What is a scotoma?

Answer 28

A small blind spot in the visual field

Question 29

What is perimetry?

Answer 29

A standardized testing measure; Patient fixates on black dot in the center of a large, white hemisphere; a small light is moved around the field, the task is to indicate when the light is visible

Question 30

What is the difference of visual agnosia & visual form agnosia?

Answer 30

Visual agnosia -> inability to recognize objects; Visual form agnosia -> inability to recognize the form of object (ex. line drawings of objects)

Question 31

What are the three identifying features of Balint syndrome?

Answer 31

1) Optic ataxia (deficit in visually guided hand movements); 2) Oculomotor apraxia (deficit in voluntary horizontal eye movements); 3) Simultagnosia (inability to perceive two objects presented simultaneously)

Question 32

What is prosopagnosia?

Answer 32

Deficit in facial & handwriting recognition (including their own)

Question 33

What are the two types of object agnosia?

Answer 33

Apperceptive agnosia (aka Visual form agnosia); Associative agnosia

Question 34

What is the difference between apperceptive (visual form) & associative agnosia?

Answer 34

Apperceptive (ex. simultagnosia) -> any failure of object perception in which basic visual functions (acuity, color, motion) are preserved; Associative -> inability to recognize an object despite being able to perceive it

Question 35

What is the difference between dorsal & ventral simultagnosia?

Answer 35

Dorsal simultagnosia -> cannot see more than one object at a time; Ventral simultagnosia -> can see more than one object at the same time; unable to perceive unified picture/derive meaning from it

Question 36

Visual agnosias are always associated with which visual perception stream?

Answer 36

Ventral

Question 37

What is visuospatial agnosia?

Answer 37

Disorder of spatial orientation; loss of one's sense of "whereness"/deficit in understanding spatial relationships of objects

Question 38

What is topographic disorientation?

Answer 38

The loss of ability to orient oneself around a familiar environment -> one kind of visuospatial agnosia

Question 39

What is aphantasia?

Answer 39

The inability to generate mental images

Question 40

What do the stripe differences represent in area V2?

Answer 40

Thin stripe -> color perception; Thick stripe -> form; Pale stripe -> motion