LECTURE 27 - closed loop control : blindsight Flashcards

1
Q

what is the extrageniculate visual pathway ?

A

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)

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2
Q

what can happen if you have a leision to V1 ?

A
  • 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
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3
Q

what is a scotoma ?

A

is a blind spot in the visual field

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4
Q

what is agnosia ?

A

impaired ability to recognize faces or objects

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5
Q

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

A

extrageniculate pathway

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6
Q

what is a shorter pathway; V1 or extrageniculate pathway ?

A

extrageniculate (fewer synapses = shorter pathway)

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7
Q

what makes a pathway shorter ?

A

fewer synapses

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8
Q

what is saccade suppression ?

A

eyes moving at maximum velocity

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9
Q

what is the double-step paradigm ?

A

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

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10
Q

what do they do in the double-step paradigm ?

A
  • 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.
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11
Q

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

A

target “jump” / pertubation

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12
Q

when does a target “jump” occur ?

A

occurs when eyes are moving at a maximum velocity

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13
Q

which paradigm uses a double step paradigm >

A

the double-step paradigm closed loop control

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14
Q

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

A

no they cannot

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15
Q

who preformed the double-step paradigm graphs ?

A

goodie et al.

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16
Q

what is backwards masking ?

A

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

17
Q

describe the backwards masking experiment :

A
  • 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
18
Q

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

A

an inverse phenomenon

19
Q

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

A

movement time decreases while target size increases

20
Q

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

A

emphasis the four red dots

21
Q

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

A

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

22
Q

how is the backwards masking experiment performed ?

A
  • 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
23
Q

what are feedback delays ?

A

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

24
Q

dynamic + unexpected = ___ ms

A

75

25
Q

who preformed the feedback delays experiment ?

A

zelaznik et al.

26
Q

describe the zelaznik et al. experiment :

A
  • 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
27
Q

which visual pathway takes longer due to more synapses ?

A

dorsal visual pathway

28
Q

was there more or less errors with lights on ?

A

slightly less errors with lights on