Vision and Brain Science B44 Brain...
Transcript of Vision and Brain Science B44 Brain...
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Vision and BrainScience B44
Lecture 23Brain
Damage
Brain Damage
1. Types of damage2. Agnosia3. Prospoagnosia4. Neglect
to eyes - injury, disease, cataractsto optic nerve - injury, diseaseto cortex - injury, disease, stroke, CO
1. Types of damage
Human cost, benefit to patientSpecificity of damage -- brain imagingLocalizing from loss of functionSerial hierarchy vs parallel pathways
What can we learn from pathology?
2. Visual Agnosia
damage to ventral pathwaycortical blindness or mind
blindnesscannot recognize objects, usually
cannot recognize faces eithere.g., patient DF cannot recognize
objects or even reportorientation
may include distortion of patterns, like DF’s caseor just inability to integrate, recognize or name
objects which are clearly seenin both cases, patient may make appropriate motor
responses to the object (dorsal pathway)occasionally, just recognition of faces affected
(prosopagnosia, Pauline)or spared (CK)typically permanent
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Patient can see details but cannot name objectsor describe their function
But makes appropriate gestures with his hands
Objectrecognition
Lateral occipital cortexfMRI shows activity here when performing object
recognition tasksDamage here leads to object recognition problems:
visual agnosia
inability to integrate parts of objectin order to recognize or name itSometimes can use distinctive features to
recognize wholehigh contrast images often used as test for
loss of integration
visual agnosic often good at individual featuresbad at combinationsno worse than normals with mixed distractors
Easy for agnosicEasy for normal
Hard for agnosicEasy for normal
Hard for both
Visual Search
3. Prosopagnosia
Paulette
Can see details but can’t recognize familiar facesCan tell a face from a nonfaceEmotion recognition can be sparedRecognize friends from voice, gait, hair style, etc.
The Man Who Mistook His Wifefor a Hat
Intelligence, musical abilities unaffectedGradual onset from tumor (or degenerative disease
of visua areas)Problems with object and face recognitionRecognize friends from features, voice, gait, hair
style, etc.
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Congenital ProsopagnosicsDo not recognize friends, family, self. This bothersfriends a great deal.
Yesterday I went to pick my youngest son up fromdaycare. I did not recognize him, and I did not knowwho he was. I recognized him by his clothing.
I was about 12YO, and I was walking down an aisle thathad columns covered with mirrors (I have a LOT oftrouble with mirrors). I saw a girl walking toward me,and I thought to myself, "Boy, is SHE ugly!" You canimagine how depressed I was when I realized it was me!
Face recognition
Ventral temporal cortex:fusiform face area (FFA)
fMRI shows activity herewhen performing facerecognition tasks
Damage here leads to facerecognition problems -prosopagnosia
Why a face area?Need to recognize individual facesOnly need to identify the category of objectsThis is a beet or this a lobsterBut not an individual beet or a specific lobster agnosia without prosopagnosia
CK head injury at age 17 while joggingnormal visual acuity, language, reasoningdraws well but can’t identify latercan’t identify food in cafeterialarge toy soldier collection as a child
Can lose object recognition butspare face recognition
Normals
CK
66%
68%
inverted
71%
14%
disguised
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Video of CK
Prosopagnosia(Paulette)
earlyvision
objects
faces
words
Double dissociation
patient CK
objects
faces
words
earlyvision
loss of attention or awareness to contralesional sidedamage to dorsal pathway (parietal lobes)difficulty in moving attention around in that fieldespecially if competing item in good field bisection task, clock task
4. Neglect: deficits for left side of worldleft side of objects (at any location)left side of visual fieldleft side of imageryleft side of dinner
typically temporarysometimes deny any
lossimplication for logic
of thought?
Artist’s selfportraits as herecovers from
neglectArtist sees these asnormal and complete
drawings
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Imagery and neglectloss of attention or awareness to
both sidesdamage to both parietal lobesreport only one object at a timeeyes never movetypically temporary
Balint's Syndrome
Balint's Syndrome
Types of damageAgnosiaProspoagnosiaNeglect
1 Minute QuizMonday - finals for
Observation paper prizes
Summary
Agnosia: loss of object recognitionProsopagnosia: loss of face recognitionCongenital prosopagnosia: lost since birthDouble dissociation: two deficits that are lost
independentlyNeglect: inability to move attention to one side of
spaceBalint’s syndrome: inability to move attention to
either side
Glossary