LECTURE 27 - closed loop control : blindsight

Question 1

what is the extrageniculate visual pathway ?

Answer 1

aneural pathway in the brain that processes visual information that bypasses the primary visual cortex, (consists of a set of subcortical structures, including the superior colliculus, the pulvinar nucleus of the thalamus, and the accessory optic system)

Question 2

what can happen if you have a leision to V1 ?

Answer 2

• blindness/partial blindness in one or both eyes
• scotoma and agnosia
• difficulty in perceiving motion, depth, and form
• visual hallucinations or distortions, such as seeing objects that aren’t there / misinterpreting the shape/size of objects

Question 3

what is a scotoma ?

Answer 3

is a blind spot in the visual field

Question 4

what is agnosia ?

Answer 4

impaired ability to recognize faces or objects

Question 5

what is considered an “older pathways” that is dynamic and unexpected ?

Answer 5

extrageniculate pathway

Question 6

what is a shorter pathway; V1 or extrageniculate pathway ?

Answer 6

extrageniculate (fewer synapses = shorter pathway)

Question 7

what makes a pathway shorter ?

Answer 7

fewer synapses

Question 8

what is saccade suppression ?

Answer 8

eyes moving at maximum velocity

Question 9

what is the double-step paradigm ?

Answer 9

a technique used in neuroscience research to study the neural mechanisms underlying sensorimotor integration, attention, and decision-making

Question 10

what do they do in the double-step paradigm ?

Answer 10

• adds a second target that appears briefly at a different location before the main target
• the timing of the appearance of the second target is manipulated to influence the saccade trajectory towards the main target.

Question 11

in the double-step paradigm; 25% of trials =

Answer 11

target “jump” / pertubation

Question 12

when does a target “jump” occur ?

Answer 12

occurs when eyes are moving at a maximum velocity

Question 13

which paradigm uses a double step paradigm >

Answer 13

the double-step paradigm closed loop control

Question 14

can people with lesions participate in this rapid ability to make that motor system connection (hands moving to the new target) ?

Answer 14

no they cannot

Question 15

who preformed the double-step paradigm graphs ?

Answer 15

goodie et al.

Question 16

what is backwards masking ?

Answer 16

renders a visual stimulus invisible by presenting a second stimulus shortly (e.g., 40 ms) after the first

Question 17

describe the backwards masking experiment :

Answer 17

• presented a matrix of differently sized circles (4)
• had 4 red dots surrounding one circle (target circle)
• perception and action
• movement time decreases while target size increases

Question 18

what type of phenomenon is present in the backwards masking experiment ?

Answer 18

an inverse phenomenon

Question 19

what are the results when a mask is worn in the backwards masking experiment vs no mask …

Answer 19

movement time decreases while target size increases

Question 20

when you mask the target during the backwards masking experiment what is there an emphasis in?

Answer 20

emphasis the four red dots

Question 21

what was the perceptual task accuracy % results in the backwards masking experiment ?

Answer 21

no-mask = 96%
mask = 56% (basically guessing and perceptionally unaware)

Question 22

how is the backwards masking experiment performed ?

Answer 22

• a technique used to study visual perception and consciousness
• involves presenting a brief visual stimulus, followed immediately by a second visual stimulus
• the mask is designed to interfere with the processing of the first stimulus by occupying the visual system and limiting the time available for the first stimulus to be perceived
• As a result, the first stimulus may not be consciously perceived, or may be perceived only partially or inaccurately

Question 23

what are feedback delays ?

Answer 23

refer to the time delays that occur in the transmission of feedback signals in a closed-loop control system

Question 24

dynamic + unexpected = ___ ms

Answer 24

75

Question 25

who preformed the feedback delays experiment ?

Answer 25

zelaznik et al.

Question 26

describe the zelaznik et al. experiment :

Answer 26

• participants completed vision or no vision aiming movements
• movements to be completed in 75 to 675 ms with or without vision
• turned lights off/on in a room and point at a target
• having people point in two movement times

Question 27

which visual pathway takes longer due to more synapses ?

Answer 27

dorsal visual pathway

Question 28

was there more or less errors with lights on ?

Answer 28

slightly less errors with lights on