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PHGY314 > Visual system Dr. Clery > Flashcards

Visual system Dr. Clery Flashcards

1
Q

what 2 thalamic nuclei are involved in vision?

A

pulvinar, lateral geniculate nucleus

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2
Q

what do the cornea and the lens do? which one can accomodate?

A

refract light; lens can accomodate (move)

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3
Q

what controls the lens shape?

A

ciliary muscles

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4
Q

what is myopia?

A

nearsighted = far away images are blurry (eyeball is too long)

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5
Q

what is hypermetropia?

A

farsighted = close objects are blurry (eyeball too short / hyperopic)

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6
Q

what is astigmatism?

A

the lens or cornea are not spherical

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7
Q

what is presbyiopoa?

A

lens gets stiff and is unable to accomodate for near vision

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8
Q

what is cataract?

A

change in the lens color

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9
Q

LAYERS OF THE RETINA

A
  • pigment epithelium
  • photoreceptor outer segments
  • outer nuclear layer
  • outer plexiform layer
  • inner nuclear layer
  • inner plexiform layer
  • ganglion cell layer
  • nerve fiber layer
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10
Q

are there more rods or cones photoreceptors?

A

20x more rods than cones

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11
Q

what is the pathway of light

A

light -> photoreceptors -> electrical signal -> bipolar cells -> ganglion cells -> brain

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12
Q

what causes blurry vision?

A

different points from a same object on the retina

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13
Q

what are rods vs cones sensitive to?

A

rods are highly sensitive to light
cones are sensitive to color and shapes

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14
Q

rods and cones: which on is for night vision?

A

rods because they are most sensitive to light

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15
Q

how are photoreceptors in the dark?

A

depolarized

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16
Q

how do photoreceptors act in the dark?

A

produce a constant flow of neurotransmitter release onto bipolar cells

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17
Q

what value is the resting potential

A

-40mv

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18
Q

how are photoreceptors cGMP levels at rest?

A

high

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19
Q

what happens when light shines on the photoreceptor

A

Na+ channels close, K+ channels stay open -> photoreceptor becomes hyperpolarized

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20
Q

name the order the the cells that light hits first

A

ganglion cell, amacrine cell, bipolar cell, horizontal cell, photoreceptors

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21
Q

rods or cones: which is used for peripheral vision vs foveal vision?

A

peripheral vision = rods
foveal vision = cones

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22
Q

rods or cones: which function in scotopic vs photopic vision?

A

scotopic = rods
photopic = cones

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23
Q

can rods see color?

A

no

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24
Q

are rods or cones saturated in daylight?

A

rods because they are highly sensitive to light

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25
Q

do rods or cones have a high temporal and spatial resolution?

A

cones

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26
Q

do rods or cones peak at the fovea?

A

cones

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27
Q

what wavelengths of light can we see?

A

400 to 800

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28
Q

what are rods vs cones threshold in photons?

A

rods = 1 photons
cones = 100 photons

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29
Q

what current is dark current?

A

about -40mV

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30
Q

what is the problem of limited dynamic range?

A

we can “adjust” the lumination to see darker or lighter details, but can hardly see both at the same time

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31
Q

light adaptation is a solution to what problem?

A

the fact that we can’t have 10 photoreceptors for each light intensity/color

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32
Q

what causes light adaptation?

A

chemical changes in photoreceptors

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33
Q

what happens to cGMP when luminance increases? why?

A

gradual increase in cGMP to restore the membrane potential

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34
Q

what are the 2 main consequences of the way our vision adapt to light?

A
  1. cells are unresponsive to uniform light
  2. brightness measurement are relative (its a comparison)
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35
Q

what cell is the output of the retina?

A

retinal ganglion cells

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36
Q

what cells do ganglion cells received input from?

A

bipolar cells

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37
Q

what is ganglion cell’s output?

A

brain (optic nerve)

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38
Q

how do ganglion cells communicate?

A

via APs

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39
Q

what type of RF can ganglion cells have?

A

achromatic or colour-opponent

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40
Q

what are the colors of colour-opponent RFs?

A

green/red and yellow/blue(purple)

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41
Q

explain and on-center off-surround ganglion cell?

A

center responds to a small spot of light if it is BRIGHTER than the background
surround responds to a small spot of light if it is DARKER than the background

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42
Q

what happens if light shines on the entire on-center off-surround RF of a ganglion cell?

A

no change in AP because the signals cancel eachother out

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43
Q

what size are the RFs in central fovea?

A

small

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44
Q

what is Hermann Grid Illusion?

A

illusion of grey at intersection of black squares because the on-center ganglion cell responses are a bit weaker at the intersections due to the off-surround

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45
Q

what is different between color opponent RFs and achromatic RFs in ganglion cells?

A

in achromatic RFs a bright surround will shut down signal in an on center off-surround.
in color opponent, a red surround won’t affect a red-on center, green-off surround RF.

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46
Q

what happens if you shine green light in the center of a red-on center, green-off surround?

A

nothing; APs fire normally

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47
Q

what happens if you shine red light on the entire RF of a red-on center, green-off surround?

A

increase AP

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48
Q

what % of males are color blind? why?

A

10%. cus the mutation is on the x chromosome

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49
Q

color blindness results from problem with what photoreceptors?

A

long or medium wavelength photoreceptors

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50
Q

The most common form of color blindness (deuteranomaly) involves a mutation that shifts ____-________ _____ towards the ___ end of the spectrum

A

medium- wavelength cones;
red

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51
Q

what is the colour-opponent theory?

A

Perception of colour is linked to neurons that measure the difference between activity in different cone types.

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52
Q

why do we still see a green on red cross after staring at a red on green cross?

A

because we fatigue the red cones in one part of the retina and green cone sin the other part (REDUCED INHIBITORY INFLUENCE)

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53
Q

What are some evidences that colour perception is dependent on measuring the difference between cones of different wavelenght (colour-opponent theory)?

A
  • We never perceive colours that appear reddish-green or bluish-yellow.
  • Adapting one colour leads to illusory perception of the opponent colour.
  • Retinal ganglion cells have opponent responses to different wavelengths.
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54
Q

what kind of ganglion cells are achromatic?

A

magnocellular cells

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55
Q

what kind of ganglion cells are colour-opponent?

A

parvocellular cells

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56
Q

where on the retina are magnocellular ganglion cells located?

A

outside the fovea

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57
Q

how is the resolution of magnocellular vs parvocellular ganglion cells?

A
  • magnocellular have low spatial resolution but high temporal resolution
  • parvocellular have high spatial resolution but low temporal resolution
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58
Q

what kind of visual information are magno vs parvocellular ganglion cells concerned with?

A
  • magnocellular are concerned with change over time (motion) (remember they are achromatic)
  • parvocellular are concerned with fine spatial detail (form)
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59
Q

what size are magno vs parvocellular ganglion cells receptive field?

A
  • magnocellular have large receptive fields
  • parvocellular have small receptive fields
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60
Q

name the visual pathway

A

retina -> optic nerve -> optic chiasm -> optic tract -> LGN -> optic radiation

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61
Q

what happens if you lesion the right optic tract?

A

you loose left vision in both eyes

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62
Q

what happens if you lesion the middle of the optic chiasm?

A

loose the external/lateral vision in both eyes

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63
Q

what happens if you lesion the right optic radiation close to LGN?

A

loose the top left quadrant of both eyes

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64
Q

the left side of our visual field is in what brain hemisphere?

A

right (opposite hemisphere)

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65
Q

a partir de quelle partie du visual pathway will a lesion cause a homonymous deficit (field loss in the same halves of the visual field for both eyes)

A

optic tract lesion and after (optic radiations)

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66
Q

how are LGN RFs?

A

same as ganglion cells:
- magnocellular are color-blind
- parvocellular are color selective

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67
Q

in what layers are magno and parvocellular LGN cells located?

A

1,2 = magno
3, 4, 5, 6 = parvo

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68
Q

name each LGN layer and if they carry info from ipsi/contralateral eye?

A

1 contra
2 ipsi
3 ipsi
4 contra
5 ipsi
6 contra

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69
Q

remember, what do magno vs parvocellular “see”?

A

magno = motion
parvo = shape details, color

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70
Q

what is contrast sensitivity?

A

A = describing observer’s ability to see dim gratings in %

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71
Q

low % of contrast sensitivity means what?

A

that you can see grating even if the colors are very similar

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72
Q

what is spatial frequency sensitivity?

A

w = way of describing an observer’s ability to see gratings of different spatial frequencies

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73
Q

what is a high spatial frequency?

A

when you see bars even when they are super close to eachother

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74
Q

formula for sinewave grating?

A

stimulus = A * sin(wx)
where A controls the contrast
w controls the spatial frequency

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75
Q

what is temporal frequency sensitivity?

A

a way of describing an observer’s ability to see gratings that flicker at different rates

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76
Q

do dogs have high or low temporal frequency sensitivity?

A

low (can’t see fluidely)

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77
Q

how is the velocity of a grating calculated?

A

temporal frequency / spatial frequency

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78
Q

how will increase the spatial frequency or the temporal frequency affect velocity?

A

Increasing the temporal frequency increases the velocity. Increasing the spatial frequency decreases the velocity.

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79
Q

what type of LGN cells are responsible for seeing the contrast at high speed?

A

magnocellular

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80
Q

what happens when you lesion layer 1 and 2 (magno) of the LGN with a chemical? the perception of what kind of stimuli is impaired?

A
  • monkey’s contrast sensitivity decreases as the velocity of the stimulus increases
  • no effect on immobile object
  • ->impairs perception of FAST-MOVING STIMULI
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81
Q

what happens to monkeys contrast sensitivity when you lesion layer 3 TO 6 (parvo) of the LGN?

A
  • contrast sensitivity decreases as spatial frequency increases (reduced sensitivity to gratings)
  • color perception is completely eliminated (no chromatic contrast sensitivity)
  • no effect when changing temporal frequency (only decreases sensitivity for slow motion)
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82
Q

why is spatial frequency harder to see?

A

because the bars get closer and closer to each other

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83
Q

what is acuity? what LGN lesions affect it?

A

ability to perceive gratings at high spatial frequencies.
affected by parvo lesions

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84
Q

what % of retinal output goes to the superior colliculus?

A

10%

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85
Q

what is the superior colliculus?

A

medial brain region that orients you to things in the environment

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86
Q

from what type of ganglion cells does the superior colliculus get input from? why?

A

mostly magnocellular cells:
- superior colliculus have big RFs, can’t see details

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87
Q

what is homonymous hemianopia?

A

can’t see half the visual field from each eye

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88
Q

name characteristics of blindsight

A
  • does not reach awareness
  • gets activated by large stimuli
  • Most effective for low spatial frequencies and high temporal frequencies
  • Little sensitivity to colour
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89
Q

how does vision restoration therapy work?

A

stimulus of moving white dots can help recover part of the vision; also with auditory feedback

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90
Q

what type of neurons must be responsible for blindsight? why?

A

magnocellular neurons because they are color blind, encode motion, and respond to big things

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91
Q

what were the results of vision restoration therapy?

A

contrast sensitivity was increased! (lower CONTRAST THRESHOLD)

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92
Q

how many cells are in retina vs V1?

A

1 million cells in retina
200 millions in V1

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93
Q

what does it mean that the projection from the LGN to V1 is retinotopic?

A

neurons that are physically near each other respond to similar parts of visual space

94
Q

the mapping of space in V1 is _________ of eye of origin

A

independent

95
Q

what measure on the retina described the size of an object?

A

the angle it covers on the retina

96
Q

what is the cortical magnification factor?

A

Mc = the amount of space in the cortex(mm) occupied by an object of a given size (angle)

97
Q

what is in this formula?
Mc = A / (E + k)

A

Mc = magnification factor
E = position on the retina relative to the fovea
A, k = constants

98
Q

bigger E means what for the magnification factor? (E = position on the retina relative to the fovea)

A

bigger E = smaller Mc

99
Q

input from the LGN goes to what layer of the visual cortex?

A

layer 4C

100
Q

what are ocular dominance columns?

A

compartments from layer 4C that divide info from right vs left eyes (only one eye is represented in each column)

101
Q

what differentiates the layer 4C sublayers?

A

4Ca is all magno cells.
4Cb is all parvo cells

102
Q

where does layer 4C project to?

A

to the other V1 layers

103
Q

where does layer 2/3 of V1 project to?

A

extrastriate cortex

104
Q

where does layer 5 of V1 project to?

A

subcortex (ex superior collliculus)

105
Q

where does layer 6 of V1 project to?

A

feedback projections to the LGN

106
Q

what is V1 (area 17 / striate cortex) responsible for?

A

conscious vision

107
Q

do LGN neurons respond to different bar orientations?

A

no

108
Q

do V1 neurons respond to different bar orientations?

A

yes

109
Q

When probed with a small spot, a V1 cell behaves somewhat like an ___ cell

A

LGN (on center off surround)

110
Q

V1 orientation selectivity is thought to emerge from what?

A

from the spatial arrangement of ON and OFF-center LGN inputs

111
Q

how are V1 RFs compared to LGN?

A
  • larger
  • more sophisticatedly tuned
  • organized into columns
112
Q

what aspect of vision is represented by V1 neurons?

A

every aspect including shape, motion, colour, depth

113
Q

what do ‘simple cells’ in the visual cortex respond to?

A

light and dark stimuli

114
Q

what can you predict by mapping subregions of visual cortex simple cells?

A

can predict the response to a more complicated stimulus than dark/light

115
Q

what would you “see” in the V1?

A

weird distorted upside down picture of our visual field

116
Q

the fact that LGN only have circular RF keeps them from seeing what?

A

LGN neurons can’t “see” edges / bars

117
Q

in V1, there is an alternation of __ _____ __ ______ stripes of LGN cells

A

on-center and off-center

118
Q

what is different from complex cells vs simple cells?

A
  • complex cells have no discernable subregions and respond to an orientation no matter where it is
  • their orientation CAN NOT be predicted from its response to a small spot of light
119
Q

how do complex cells respond to light and dark stimuli in their receptive field?

A

respond equally to light and dark stimuli

120
Q

simple vs complex cells convey information about what?

A
  • Simple cells convey information about orientation and local
    contrast
  • Complex cells convey information about orientation, but
    NOT local contrast
121
Q

complex cell’s RF are built from what?

A

from simple cell RFs

122
Q

how are the simple cells that construct the receptive field of complex cell?

A

they have the same orientation but opposite arrangements of ON and OFF regions

123
Q

from what we know about cortical layers, in what layers would simple vs complex cells be?

A

simple cells in layer 4 (get LGN input), complex cells in other layers

124
Q

what were they able to show via anatomical labelling after injecting die in only 1 eye?

A

ocular dominance column in 4C (separation of ipsilateral and contralateral input)

125
Q

one ocular dominance column has many what?

A

many orientation column

126
Q

whats a hypercolumn?

A

a column in which all the orientations are represented from both eyes (right and left ocular dominance columns together)

127
Q

the orientation selectivity are dependent on what?

A

depend on the development: what stimulus you are exposed to as you grow

128
Q

how did they show that orientation selectivity depends on development?

A

exposed cats to different orientations: the cat has more cortical area dedicated to the orientation they were most exposed to

129
Q

what is amblyopia?

A

imbalance between left and right eye

130
Q

what did the post-mortem picture of a human brain from a patient who had lost an eye show? with cytochrome oxidase staining

A

he still has ocular dominance column even after not using one eye for years

131
Q

why is it important to act early on amblyopia?

A

formation of ocular dominance columns happens early and stays for the rest of your life

132
Q

what V1 cell don’t respond to orientation?

A

blobs

133
Q

in what V1 layers are blobs found?

A

upper layers (2/3)

134
Q

what do blobs respond to?

A

colour

135
Q

what is different between color opponent LGN vs V1 (blobs) cells?

A

blobs are DOUBLE-OPPONENT cells.
Not just red-on-center, green-off-surround, but red-on-center green-off-center and red-off-surround green-on-surround

136
Q

what is simultaneous color contrast?

A

the tendency of the visual system to perceive colors in a way that depends on the colors that surround
them

137
Q

why do some people see the dress blue/black vs yellow/white?

A

because we don’t have a lot of information about the background in the picture - brain makes assumptions

138
Q

what is colour perception related to?

A

differences between cone outputs along with more abstract assumptions about the environment

139
Q

what are orientation columns?

A

columns in which all neurons are tuned to the same orientation

140
Q

how do ocular dominance columns respond in layer 4C vs in other layers?

A

In layer 4C cells respond to input from only one eye (as in the LGN).
In other layers, cells
are binocular but still respond more to one
eye than to the other.

141
Q

within a single hypercolumn, neurons have RFs that represent similar what?

A

similar locations in space

142
Q

name 4 things for which the visual cortex can be selective?

A

Orientation
Motion direction
3D depth (binocular disparity)
Stimulus length

143
Q

how can we have motion direction selectivity in the visual cortex?

A

via LGN inputs that are shifted in space and delayed in time and when they arrive synchronously to V1, allow APs to go above threshold only when stimuli goes in the preferred direction

144
Q

what is the aperture problem?

A

Local measurements of edge motion are one-dimensional, so V1 neurons see the motion as perpendicular to the orientation of an edge and give misleading info on direction of movement

145
Q

the aperture problem means that V1 neurons don’t have the ability to communicate information about what?

A

velocity

146
Q

The size of an object is typically described by the size of the angle it covers on the retina, and therefore the visual system confuses size with what?

A

confuses size with depth

147
Q

how does binocular disparity work?

A

disparity-selective neurons in V1 fire at specific horizontal disparity measurements

148
Q

Selectivity for binocular disparity can be found in simple cells whose LGN
inputs have slightly different what?

A

different RF positions in the two eyes

149
Q

Binocular disparity depends on the depth of the object relative to what?

A

relative to the plane of fixation

150
Q

what is endstopping?

A

reduced response to long edges

151
Q

how does endstopping work?

A

long bars go in the RFs of cells beside the RF of interest and the neighboring neurons inhibit the middle one via inhibitory horizontal connections

152
Q

why could endstopping be super useful?

A

to detect curvature

153
Q

why are curvatures so important to see?

A

is is easier to differentiate an object when you have just the curves vs just the straight lines

154
Q

what cells are horizontally connected to eachother?

A
  • cells from different hypercolumns in upper layers of V1 that have the same orientation or color specificity
  • also Blobs are interconnected
155
Q

what is contour integration?

A

Lines of similar orientation stand out against a background of random orientations

156
Q

how does contour integration work? what kind of connections does it involve?

A

neighboring cells are excited by the same stimulus (opposite of endstopping)
- involved excitatory horizontal connections

157
Q

the ventral pathway connects V1 to what cortex?

A

inferotemporal cortex

158
Q

the ventral pathway is responsible for what part of vision?

A

shapes

159
Q

lesions of the ventral pathway causes what?

A

normal vision, but loose the ability to see certain things ex to recognize faces

160
Q

what cells are mostly involved in the ventral pathway?

A

parvocellular cells

161
Q

what cells are mostly involved in the dorsal pathway?

A

magnocellular cells

162
Q

what is the dorsal pathway mostly concerned with?

A

motion

163
Q

what disease can come from ventral pathway lesion?

A

Prosopagnosia: inability to recognize faces

164
Q

what disease can come from dorsal pathway lesion?

A

Akinetopsia: motion blindness; no smoothness in motion ex can’t pour coffee in mug

165
Q

what are the 3 roles for extrastriate visual areas that we went over?

A
  1. more directly involved in guiding visual perception and behavior
  2. useful to measure quantities that can’t be measured with small RF
  3. interact with our cognitive state
166
Q

remember: parvocellular vs magnocellular input go to what 4C sublayer in V1?

A

magnocellular goes to 4Calpha
parvo goes to 4Cbeta

167
Q

where do blob cells project to in V2?

A

thin stripes in V2

168
Q

where do the rest (non-blob) cells project to in V2?

A

pale stripes and thick stripes

169
Q

what stripes project to the ventral pathway? to what area?

A

thin and pale stripes project to V4

170
Q

what stripes project to the dorsal pathway? to what area?

A

thick stripes project to MT

171
Q

what information is contained in each type of stripe?

A

Thin stripes: colour
Pale stripes: orientation
Thick stripes: orientation, direction

172
Q

what visual pathway area can see illusory contours?

A

V1 neurons can’t see it,
V2 neurons can

173
Q

give an example of why illusory contour is important?

A

used to see texture boundaries and estimate the depth of things

174
Q

other than illusory contour how else does V2 contribute to perception of shape and depth?

A

processing of angles

175
Q

how do V2 lesions affect orientation, color, motion direction, and texture discrimination

A
  • no effect on orientation, color, motion direction discrimination
  • impairment of texture discrimination composed of multiple orientations (seeing the bars in different orientation in a pattern)
176
Q

basically what are the 2 things encoded in V2 that aren’t encoded in V1?

A

illusory contours and angles

177
Q

what seems to be V3 role?

A

V3 appears to contain columns for processing retinal disparity (near/far objects)

178
Q

what is MT?

A

middle temporal area (but it’s not in temporal lobe) (also called V5)

179
Q

in what visual pathway is MT?

A

it’s the beginning of the dorsal pathway

180
Q

where does MT get its input from?

A
  • from the thick stripe in V2, that get their input from layer 4B of V1 that get input from 4Ca
  • directly from V1
181
Q

MT gets info for what type of stimuli? because it gets input from what layer?

A

motion direction because it gets input from V1 layer 4B

182
Q

what are MT output involved in?

A

motion perception and eye movement control and self-motion

183
Q

where do MT outputs go?

A

MST -> Parietal cortex

184
Q

what is also sometimes called the dorsal pathway?

A

“where” pathway

185
Q

MT neurons show specificity for what?

A

for motion direction

186
Q

MT is organized in ?

A

columns for different direction preference

187
Q

how did they test for the MT role in motion direction selectivity?

A

microstimulation of single MT direction columns while the monkey was doing a motion direction task.
It biased the monkey’s perception.

188
Q

what were the results of the MT microstimulation experiment?

A

Microstimulating a column that preferred rightward motion biased the animal’s percept toward rightward motion

189
Q

can monkeys already have innate biased for motion direction?

A

yes

190
Q

what happens to ppl with MT lesions/MT damage?

A

can not see if the dots are going a certain way unless there is 100% coherence (loose perception of motion)

191
Q

as you go higher in the hierarchy of the visual system, you get ________ ___

A

larger RFs

192
Q

the first activity we observe in MT when a bar moves is based on what?

A

on the motion preference for the orientation

193
Q

what cells can solve the aperture problem?

A

“later” MT cells that act after about 60ms and understand the correct direction of motion

194
Q

how does MT solve the aperture problem?

A

MT has “smart” cells that can select which input is important to solve the problem

195
Q

what input are most important for MT to solve the aperture problem?

A

the corners of the moving object are most important. MT can ignore the edges

196
Q

how big are MT’s RFs compared to V1?

A

10x bigger

197
Q

dorsal visual pathway neurons respond to moving stimuli, with little dependence on what?

A

shape, color, texture

198
Q

what type of information do you loose in MST?

A

information about the precise location of things

199
Q

where does the retinotopic map appear in the visual pathway

A

V1

200
Q

what’s the difference between MT and MST tuning?

A

MT are tuned for translation, MST are tuned for more complex motion like optic flow

201
Q

what is the definition of optic flow?

A

combinations of translation, rotation and expansion

202
Q

the complex motion patterns in MST are bigger than what?

A

bigger than the MT receptive fields

203
Q

MST is organized in?

A

in columns clustered based on selectivity for complex motion stimuli (rotations, expansions, contractions)

204
Q

for what process must MST neurons be most useful for?

A

navigation (because they see optic flow)

205
Q

individual MST neurons can be tuned for what?

A

tuned to the direction of heading in large optic flow

206
Q

how did microstimulation of a leftward MST column affect monkeys?

A

in he case we saw it undid the animal’s rightward bias of heading direction

207
Q

what is different about MST eye of visual field?

A

Unlike in V1, V2, or MT, MST receptive fields often
include parts of the ipsilateral visual field

208
Q

what is the ventral pathway specialized in?

A

shapes

209
Q

Where does V4 get the input from?

A

V1 upper layers and thin and pale stripes of V2

210
Q

what are the structures of the ventral pathway?

A

LGN -> V1 -> V4 -> IT

211
Q

does V4 have info about orientation?

A

yes but it is not its main job

212
Q

how does attention influences your perception of the world?

A

it increases neuronal and perceptual sensitivity

213
Q

how does attention affect the activity of neurons?

A

it multiplies their activity, increasing the amplitude of the tuning curve of the normalized response without changing the shape

214
Q

in what visual pathway area does attention have a bigger impact on neuronal response?

A

stronger effect in V4 compared to V1

215
Q

in what visual pathway is attention important? how does it change through the pathway

A

attentional enhancement is present in dorsal and ventral pathway and increase a you ascend in the hierarchy (MST/IT > V1)

216
Q

what is the behavioural measure for tilted grating?

A

How far does the grating have to be rotated before the subject gets the right answer 75% of the time?

217
Q

in humans and monkeys, how far does the grating have to be rotated before the subject gets the right answer 75% of the time?

A

around 5 degrees

218
Q

how did V4 9and TEO) lesions affect attention?

A

moneys performed poorly in the titled grating experiment in the presence of distracters, which didn’t affect monkey with intact V4.

219
Q

describe V4 receptive fields?

A

10x larger than V1 RFs, they respond to complex 3D shapes defined by curvature and/or slant

220
Q

what is IT in ventral pathway crucial for?

A

representation of complex shapes.
TO RECOGNISE OTHER PEOPLE

221
Q

how do IT neurons respond to smiley face

A

activated by face-like features

222
Q

some IT neurons respond specifically to what feature of a face?

A

profile (or side views of other objects)

223
Q

there appears to be clustering for what features in the IT?

A

clustering of columns selective for complex shapes

224
Q

what can they establish by adding noise to an image?

A

a continuum from stimuli that are just faces to stimuli that are other objects

225
Q

using the face stimuli continuum what did microstimulation of IT face-selective clusters cause in monkeys?

A

biases the mokey’s perception toward faces

226
Q

what about when they microstimulate IT face-selective cluster in humans?

A

same; patient imagined faces

227
Q

what is the middle face patch? where is it?

A

area in macaque cortex in the floor of the superior temporal sulcus that responds strongly to faces

228
Q

Perception of biological motion requires a conjunction of what?

A

conjunction of form and motion

229
Q

where did they find cells that respond to conjunction of form and motion (biological motion)

A

anterior superior temporal polysensory area STPa

230
Q

the activity in the anterior superior temporal polysensory area STPa correlated from what?

A

withthe coherence of the biological motion

PHGY314 (9 decks)

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