LECTURE 26 - closed loop control - - visual pathways

Question 1

what are the two streams of the visual pathway ?

Answer 1

dorsal and ventral stream

Question 2

where does the dorsal stream travel ?

Answer 2

V1 (primary visual cortex) to PPC (posterior parietal cortex)

Question 3

where does the ventral stream travel ?

Answer 3

V1 to inferotemporal cortex

Question 4

what does the dorsal stream support ?

Answer 4

vison for action

Question 5

what does the ventral stream support ?

Answer 5

vision for perception

Question 6

what is prosopagnosia ?

Answer 6

• face blindness is a neurological disorder characterized by the inability to recognize familiar faces
• people with prosopagnosia may have difficulty distinguishing between faces, remembering faces, or associating faces with names or identities

Question 7

what is the important case study of the closed-loop control : visual pathway and prosopgnosia ?

Answer 7

• the monkey study
• had names associated with each chimpanzee based on the features of the face
• can see features but cant put it all together

Question 8

what is one piece of evidence that shows we have a dorsal and ventral aspect

Answer 8

study by Ungerleider and Mishkin in the 1980s, the researchers trained monkeys to perform two different tasks: one involving the perception of the location of an object and the other involving the perception of the object’s identity

Question 9

what is a region of ventral visual pathway which is responsible for this now process ?

Answer 9

fusiform face region

Question 10

what is visual agnosia ?

Answer 10

a neurological condition characterized by the inability to recognize or interpret visual information, despite normal functioning of the eyes and optic nerves

Question 11

can DF identify different shapes or object features ?

Answer 11

cannot

Question 12

can DF reach out and grasp objects properly

Answer 12

yes

Question 13

does object agnosia use vision for motor contact ?

Answer 13

yes, fully intact use of vision for motor contact (movement)

Question 14

what is the first classic and simple study looking at DF’s visual abilities ?

Answer 14

model, copy and memory drawing of apple and book (milner and goodie)

Question 15

describe the visual agnosia and DF study :

Answer 15

• DF was asked to look at an object (so these would be paper drawings) and then in response, DF is asked to copy them using paper and pencil in order to copy the image

Question 16

what is the main point of the DF study ?

Answer 16

• that DF has an idea, she has a memory of what these objects look like, however when she is physically looking at those things she’s only unable to recognize these elements

Question 17

what is DF ?

Answer 17

Patient DF is a woman with visual apperceptive agnosia

Question 18

what are the two tasks in visual agnosia ?

Answer 18

PT and AT

Question 19

what does PT and AT stand for ?

Answer 19

PT = perception task
AT = action task

Question 20

what is the perception task ?

Answer 20

involves presenting a patient with a series of simple geometric shapes, and asking them to identify or match the shapes

Question 21

what is action task ?

Answer 21

involves presenting a patient with a series of common objects, such as a pen, a key, or a watch, and asking them to identify or name the objects

Question 22

what are milner and goodale responsible for ?

Answer 22

• visual agnosia
• primarily involved in the early studies of DS processing abilities and they came up with this very simple task in order to provide a very explicit demonstration of what DF can and cannot do

Question 23

what was the PT asked to do for the closed-loop control : visual agnosia ?

Answer 23

• was asked to pick up and orientate it to the slot
• slot on the door can change orientation

Question 24

what was the AT asked to do fro the closed-loop control : visual agnosia ?

Answer 24

has to physically put in the slot

Question 25

do we have separate visual pathways for perception and action ?

Answer 25

yes

Question 26

what does LOC stand for ?

Answer 26

lateral occipital cortex

Question 27

what area has leison of patients with DF ?

Answer 27

LOC

Question 28

the leison in a visual agnosia DF patient ?

Answer 28

lesion will lead to an impairment in the use of vision for perception, but not in the use of vision to control action

Question 29

what is optic ataxia ?

Answer 29

an ataxia in which patients have difficulty completing visually guided reaching tasks in the absence of other sensory cues

Question 30

which ataxia has a double dissociation ?

Answer 30

optic ataxia

Question 31

can AT (ataxia) recognize shapes, sized and object features ?

Answer 31

yes without a problem

Question 32

can AT (ataxia) reach out and grasp objects with visual control ?

Answer 32

no they cannot

Question 33

can DF (agnosia) recognize shapes, sizes and objejct features ?

Answer 33

no they cannot

Question 34

can DF (agnosia) reach out and grasp objects properly ?

Answer 34

yes

Question 35

describe patient Anne :

Answer 35

- has bilateral posterior parietal cortex lesions - has dysmetria / misreading errors - looking @ object through peripheral vision and is reaching out grasping it - in right peripheral visual field the cant catch pen but on the left side she can - improved performance = closed eyes

Question 36

fill in the two blanks "someone who has an optic ataxia will have a challenge in using _____ in order to control _____ , and so this represents the double dissociation that supports this duplex model of vision control"

Answer 36

vision and action

Question 37

when does patient Anne have improved performance ?

Answer 37

when she closes her eyes

Question 38

what is the ponzo illusion ?

Answer 38

visual illusion that demonstrates how our perception of the size of an object is influenced by the context in which it appears (scale)

Question 39

which visual pathway is egocentric responsible for ?

Answer 39

dorsal visual pathway

Question 40

which visual pathway is allocentric responsible for ?

Answer 40

ventral visual pathway

Question 41

between egocentric and allocentric which is relative and absolute ?

Answer 41

egocentric = absolute allocentric = relative

Question 42

describe the muller-layer figure ?

Answer 42

type of visual illusion in which two lines of the same length appear to be different lengths due to the addition of arrow-like fins at the ends of the lines (arrows can be oriented inwards or outwards)

Question 43

what are muller-layer figures used for ?

Answer 43

closed loop controls : visual frames of reference

Question 44

what is the muller-layer figured an example of ?

Answer 44

pictorial illusion

Question 45

what is the "lee's moving room experiment" ?

Answer 45

an experiment in sensory psychology that investigates how the brain uses visual and vestibular (balance-related) cues to perceive motion and orientation in space

Question 46

describe lee's moving room experiment :

Answer 46

- subjects asked to maintain static posture while facing the front wall - experimenter gradually moved wall forwards or backward - postural sway measured - moving wall FOWARD resulted in a dramatic forward lean - moving wall BACKWARD resulted in a dramatic forward lean - visual information is a source of afferent information controlling balance

Question 47

moving wall FOWARD resulted ______________

Answer 47

in a dramatic forward lean

Question 48

moving wall BACKWARD resulted ________________

Answer 48

resulted in a dramatic forward lean

Question 49

was lee's moving room experiment easier/more difficult for adults/kids ?

Answer 49

easier = adults harder = kids

Question 50

why was lee's moving room experiment more difficult for kids ?

Answer 50

kids dont have sophisticated nervous systems yet therefore they call on their bums