Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of...
Transcript of Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of...
![Page 1: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/1.jpg)
1
Psy280: PerceptionPsy280: Perception
Prof. AndersonProf. AndersonDepartment of PsychologyDepartment of Psychology
Week 4Week 4
![Page 2: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/2.jpg)
2
Lets enter the brain, shall we?Lets enter the brain, shall we?
![Page 3: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/3.jpg)
3
Visual maps: Multiple neuralVisual maps: Multiple neuralrepresentations of realityrepresentations of reality
![Page 4: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/4.jpg)
4
Neural convergence & divergence:Neural convergence & divergence:Complexity & parallel processingComplexity & parallel processing
Eye
![Page 5: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/5.jpg)
5
Eye to CNS�� Contralateral projectionsContralateral projections
�� RVFRVF——> left hemisphere> left hemisphere�� LVFLVF——>right hemisphere>right hemisphere
�� Multiple pathwaysMultiple pathways�� Retino-geniculate-striateRetino-geniculate-striate
pathwaypathway�� Conscious visionConscious vision
�� Retino-collicular-pulvinarRetino-collicular-pulvinarpathwaypathway�� Vision for actionVision for action�� Eye movementsEye movements�� UnconsciousUnconscious
�� Retino-SuprachiasmaticRetino-Suprachiasmaticnucleusnucleus
![Page 6: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/6.jpg)
6
Retino-geniculate-striate pathRetino-geniculate-striate path�� Vision for perceptionVision for perception
�� Conscious visionConscious vision
�� Cortical blindness: HemianopiaCortical blindness: Hemianopia�� Retina intact: Brain blindRetina intact: Brain blind
![Page 7: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/7.jpg)
7
Retino-collicular pathRetino-collicular path
�� ““BlindsightBlindsight””: Nonconscious sight: Nonconscious sight�� Visual cortical lesionVisual cortical lesion
�� Yet, above chance localizationYet, above chance localization�� Intact eye movementsIntact eye movements
�� Conclude:Conclude:�� Spared retino-collicular pathSpared retino-collicular path
�� Different Different ““kindkind”” of vision of vision
![Page 8: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/8.jpg)
8
Cortical blindness:Cortical blindness:Fear blindsightFear blindsight
XMorris et al., 2001
•Examine patient w/ cortical blindness
• Examine amygdala response to fear evoking events inthe absence of cortex/awareness
L R
![Page 9: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/9.jpg)
9
Intact/Seen Lesion/Blind
Cortical blindness:Cortical blindness:Fear blindsightFear blindsight
• Stimuli presented to intact and blind hemifield
![Page 10: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/10.jpg)
10
Intact Blind
Cortical blindness: FearCortical blindness: Fearblindsightblindsight
• Amygdala discrimination of fear in blind field
• Depends on retino-collicular pathway to amygdala
![Page 11: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/11.jpg)
11
RetinaRetina——>Suprachiasmatic>Suprachiasmaticnucleusnucleus
�� Other forms of nonconscious visionOther forms of nonconscious vision�� Non-rod, non-cone, melatonin basedNon-rod, non-cone, melatonin based
photoreceptorsphotoreceptors�� Regulation of circadian behaviorRegulation of circadian behavior
�� Humans lacking rods and conesHumans lacking rods and cones�� Sleep/wake cycles influence by lightSleep/wake cycles influence by light
�� Supported by connection between retina andSupported by connection between retina andbiological clock in the SCNbiological clock in the SCN
�� Conclude: Many types of Conclude: Many types of ““visionvision””
![Page 12: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/12.jpg)
12
Retino-geniculate pathway� Organization of LGN: Retinal origin
� Laminar structure
� Temporal/Nasal adjacent (Same VF)
![Page 13: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/13.jpg)
13
Retino-geniculate pathway:Parallel processing III
� Organization of LGN: Retinotopy� Adjacent regions in retina project
to adjacent regions of LGN
� 6 representations of retina in register
![Page 14: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/14.jpg)
14
Retino-geniculate pathway� LGN: Physiology
� Similar to retinal ganglion cells
� Center-surround
� LGN: Anatomy
� Not all retinal maps the same� Parvocellular (P-cells)
� Small cells
� Top 4 layers
� Largely Cone-based
� Magnocellular (M-cells)� Large cells
� Bottom 2 layers
� Largely rod-based
![Page 15: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/15.jpg)
15
Organization of visual cortices:Divide & Conquer!
�� BifurcationsBifurcations�� LGN LGN ——> V1> V1
�� 2 divisions2 divisions�� M & PM & P
�� V1 V1 ——> extrastriate> extrastriate�� Even greater divergenceEven greater divergence�� Maintain M & P originMaintain M & P origin
�� Differ in features (Parallel)Differ in features (Parallel)& complexity (Hierarchical)& complexity (Hierarchical)
Parvo
Magno
![Page 16: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/16.jpg)
16
M & P pathways:M & P pathways:Functional significanceFunctional significance
�� Do M & P pathways representDo M & P pathways representdifferent modes of perception?different modes of perception?
�� P-cells: colour and luminanceP-cells: colour and luminance�� Colour, form, textureColour, form, texture
�� M-cells: luminanceM-cells: luminance�� MotionMotion
�� Isoluminance studiesIsoluminance studies�� Robust motion when definedRobust motion when defined
by luminanceby luminance�� Decreased motion when defined byDecreased motion when defined by
color (isoluminant)color (isoluminant)
�� Lesions of M & PLesions of M & P
Motion
![Page 17: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/17.jpg)
17
Primary visual cortex:Striate cortex/V1/Area 17
� First cortical synapse in vision: Calcarine sulcus
![Page 18: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/18.jpg)
18
Striate cortex (V1): Retinotopy
�� 6 LGN maps 6 LGN maps ——>>1 striate map1 striate map
�� Up is downUp is down�� Right is leftRight is left�� Fovea is posteriorFovea is posterior
�� Map is distortedMap is distorted�� Cortical magnificationCortical magnification�� Like motor homunculusLike motor homunculus�� Fovea > peripheryFovea > periphery
![Page 19: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/19.jpg)
19
Neuropsychological evidence:Neuropsychological evidence:RetinotopyRetinotopy
�� Visual field deficits: ScotomasVisual field deficits: Scotomas�� Cortical blindnessCortical blindness
�� Hemianopia distinguishes between peripheral (retinal) andHemianopia distinguishes between peripheral (retinal) andcentral (cortical) blindnesscentral (cortical) blindness
![Page 20: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/20.jpg)
20
Striate cortex (V1):Eye and orientation selectivity
� Ocular dominance columns� Selective for each eye
� Orientation selectivity� Increase in complexity
relative to LGN
� “simple” cells
� Orientation detectors for
each region of retinal space
All from same portion of space
![Page 21: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/21.jpg)
21
10 min break!10 min break!
![Page 22: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/22.jpg)
22
How do we create orientationHow do we create orientationselectivity?selectivity?
�� Combine center surround cells to createCombine center surround cells to create““simplesimple”” cells cells
+-
![Page 23: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/23.jpg)
23
Does V1 have to representDoes V1 have to representevery orientation?every orientation?
�� NopeNope�� Distributed orDistributed or
coarse codingcoarse coding�� Orientation isOrientation is
coded bycoded bymagnitude ofmagnitude ofresponse acrossresponse acrossmultiple cellsmultiple cells
Orientation “tuning curve”
![Page 24: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/24.jpg)
24
Cortical magnification:Cortical magnification:The oblique effectThe oblique effect
�� Not just fovea versus peripheryNot just fovea versus periphery�� More cells/cortical space devoted to horizontalMore cells/cortical space devoted to horizontal
and vertical lines relative to obliqueand vertical lines relative to oblique
�� Physiology=Physiology=perceptionperception
Perception Brain signal: fMRI
![Page 25: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/25.jpg)
25
Orientation selectivity:Orientation selectivity:Nature or Nurture?Nature or Nurture?
�� Selective rearing during early developmentSelective rearing during early development�� Vertical or horizontal orientation blindnessVertical or horizontal orientation blindness
�� Reflects visual plasticity in V1Reflects visual plasticity in V1
Verticaldeprivation
Horizontaldeprivation
![Page 26: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/26.jpg)
26
Definitions: Visual angle andDefinitions: Visual angle andspatial frequencyspatial frequency
�� Angle of retinal projectionAngle of retinal projection�� Equal visual angle, same retinal sizeEqual visual angle, same retinal size
�� Spatial frequencySpatial frequency�� Number of light dark alternations (cycles) perNumber of light dark alternations (cycles) per
degree of visual angledegree of visual angle
![Page 27: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/27.jpg)
27
Spatial frequency channelsSpatial frequency channels
�� Visual system might decompose stimuli intoVisual system might decompose stimuli intodifferent scales (spatial frequencies)different scales (spatial frequencies)�� Small changes, big changes in fluctuation inSmall changes, big changes in fluctuation in
luminance over spaceluminance over space
Low f High f
Low High
![Page 28: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/28.jpg)
28
Fourier analysisFourier analysis
�� Can decompose eventsCan decompose eventsinto constituent spatialinto constituent spatialfrequency (SF)frequency (SF)componentscomponents
�� High SF captures edgesHigh SF captures edges
�� Descriptive or doesDescriptive or doesvisual system may usevisual system may usesimilar procedure ?similar procedure ?
![Page 29: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/29.jpg)
29
Simple cells and spatialSimple cells and spatialfrequencyfrequency
�� Tuning curves ofTuning curves ofsimple cellssimple cells
�� MaximallyMaximallyresponsive toresponsive todifferent SFdifferent SF
�� Suggests V1 doesSuggests V1 doesSF analysisSF analysis
![Page 30: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/30.jpg)
30
SF orientation coding andSF orientation coding andperceptionperception
�� Are these cells important for perception?Are these cells important for perception?�� Selective adaptationSelective adaptation
�� Exercise neurons until weak responseExercise neurons until weak response�� Like fatigued musclesLike fatigued muscles�� Examine contrast sensitivity at diff orientationsExamine contrast sensitivity at diff orientations
Dec
reas
e in
con
tras
tse
nsiti
vity
Orientation of grating40 20 0 20 40
test30°
Adapt0°
![Page 31: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/31.jpg)
31
Contrast sensitivity functionContrast sensitivity function
�� Adaptation results in selective fatigueAdaptation results in selective fatigue�� Reveals that CSF is the result of multiple SFReveals that CSF is the result of multiple SF
channelschannels
CSF
Con
tras
t sen
sitiv
ity
![Page 32: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/32.jpg)
32
SF adaptation and perceptionSF adaptation and perception�� Phenomenal and neural correlatesPhenomenal and neural correlates�� Perception determined by multiple SF channelsPerception determined by multiple SF channels�� Coarse coding across channelsCoarse coding across channels
�� Also: Perception differs for identical stimulusAlso: Perception differs for identical stimulus�� Perception parallels V1 response, not retinal imagePerception parallels V1 response, not retinal image
a
b
Neural response
![Page 33: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/33.jpg)
33
Beyond V1:Beyond V1:Higher order extra-striate corticesHigher order extra-striate cortices
![Page 34: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/34.jpg)
34
Higher order visual cortex:Higher order visual cortex:Extrastriate cortexExtrastriate cortex
�� CytoarchitectureCytoarchitecture�� Distinct from V1Distinct from V1
�� Functional correlatesFunctional correlates�� More complex features:More complex features:�� Motion, MT/V5Motion, MT/V5
�� Direction and speedDirection and speedSelectiveSelective
�� ColourColour�� DepthDepth�� FormForm
![Page 35: Psy280: Perception - University of Toronto · Psy280: Perception Prof. Anderson Department of Psychology Week 4. 2 Lets enter the brain, shall we? 3 Visual maps: Multiple neural representations](https://reader033.fdocuments.net/reader033/viewer/2022060516/5fc61c2a1c8b0e04fc46978e/html5/thumbnails/35.jpg)
35
EndEnd