Flashcards
Visual Agnosias
Cards in this deck (23)
- 1What is agnosia? What are the different types of agnosia? What is visual agnosia?Agnosia is a word that means without knowing
Visual, auditory and tactile
You cannot recognise an object just by looking at it - 2What is intact in visual agnosia? What is impaired in visual agnosia?Intact primary visual pathway, memory, object knowledge, language and object recognition using other sense
Impaired object recognition from site - 3Who identified two subtypes of agnosia and what are they? What is apperceptive agnosia? What is associative agnosia?Lissauer 1890, Apperceptive and Associative
The inability to recognise objects due to deficit in perceptual processing (trouble shape building)
Normal perceptual processing but the process of associating an object with it's meaning/purpose is impaired - 4What is apperceptive agnosia also known as? What is a difficulty in apperceptive agnosia? Give an example:Visual form agnosia
Difficulty forming a stable visual perception representation
See a 2D image and can't extract/determine different shapes to make up an object, lack of perceptual coherence, no meaningful shapes - 5Impairments in apperceptive agnosias (4 things: Which do they find hardest? How it is acquired?1. Name an object or point to which are the same/different
2. Cannot copy drawings of an object/copy anything
3. Can't read or write
4. Cannot match shapes
Identifying pictures of objects as they cannot use other cues such as size or context
Injury/illness - 6How is apperceptive agnosia tested for? What are efron rectangles? What can apperceptive agnosias detect?Efron Rectangles
They are rectangles with the same surface area but different widths/lengths, healthy participants pass this task but agnosic patients have to be double the width/length to differentiate
Obvious size difference, i.e. chair vs elephant but not small, i.e. toothbrush vs pen - 7What is intact in apperceptive agnosias? (three things)-Object knowledge (can describe from memory)
-Object memory (can draw and object from memory, however this need to be continuous, if patient pauses then has to finish the drawing they won't recognise what they have drawn)
- Recognising objects from touch - 8Which patient was test by Milner et al 1991, Goodale et al 1991 and Shenk and Milner 2006? What deficits did DF have? Where did DF have brain damage? What skills were intact in DF? What was found from these on studies?DF
Low level deficits in vision i.e. acuity
Bilateral damage to lateral occipital cortex
Visuomotor skills (he was impaired in matching the angle line with the card, but intact in actually posting the card through the hole so was intact in a meaningful action)
1.That lateral-occipital lesion lead to impaired ventral stream (associated with vision for perception) and intact dorsal stream (vision for action) which suggests that visuomotor actions are performed by the dorsal stream independent of recognition
2. More mild agnosia deficits can occur from only unilateral lesions to the LOC
3. Bilateral lesions mean the patients cannot copy/recognise at all, unilateral can recognise complete drawings of objects but not with missing bits (street 1931)
4. Unilateral lesions mean apperceptive agnosias can recognise single objects, not mixed up or overlapping ones (De Renzi 1969)(Ghent overlapping figure test)
5. Unilateral lesion means you can't recognise single objects at unusual views/orientations (Warrington and Taylor 1973) - 9Evidence for LOC in Apperceptive? Who was it? What did he do? What did he find?Grill-Spector et al 2001
fMRI activation during object and shape processing
Found activation in the LOC - 10Apperceptive LOC Evidence: Who was it? What did he do? What did he find?Ellison and Cowie 2006
TMS over LOC while performing shape discrimination task
TMS disrupts the processing therefore LOC must be involved in shape discrimination - 11Apperceptive LOC Evidence: Who was it? What did he do? What did he find?Ungerlieder and Mishkin 1982
Tested object and landmark discrimination in monkeys after lesioning the LOC
Found that this impaired object discrimination - 12Associative Agnosia: What is intact in Associative? What is impaired?Copying of drawing
Resolve overlapping figures task
Matching by shape (All above are evidence for intact perception)
When given a random object name they can give accurate information on appearance and uses but can't access this information when they see an object
recognising object by touch
Impaired: Visual object recognition, matching by function (can't match knowledge with perception), visual object and space perception battery (match silhouette with real object) and Birmingham object recognition battery (Mismatch face/body task) - 13At what stage of visual processing is the damage that causes associative agnosia? Who conducted a case study? Who was the patient? What was intact? What was impaired? What damage did he have?At the stage where visual representation is associated with stored knowledge
McCarthy and Warrington 1986
FRA
Language, spatial, visual and perceptual abilities
Recognition of presented objects and reading (woke up unable to read one day)
Left fusiform gyrus - 14Differences between apperceptive and associative agnosia (three things)1. Apperceptive drawing/copying/matching are impaired
2. Apperceptive linked with Lateral Occipital Cortex
3. Associative linked with left fusifom gyrus - 15What is everyday life like with visual agnosia (five things):1. Intact hearing, sense of touch, smell ect
2. Intact memory, cognition and speech
3. Relatively good obstacle avoidance
4. Better object recognition with real objects than pitcures
5. Issue changing because they don't recognise clothes - 16Prosopagnosia: What is prosopagnosia? What can you distinguish? What can you not distinguish? What is intact?A specific deficit in the visual recognition of faces
Can distinguish between objects and faces (across category)
Cannot distinguish between two different faces (within category)
Object recognition in intact - 17Who conducted a case study? Who was the patient? What happened to the patient? What could the patient do?Bodamer 1947
Patient was unter offizer s
Had a head wound and then could not recognise any faces
Could distinguish the elements of a face but had no sense that the features made a face (suggests a disorder of basic face perception) - 18Who studied patients with prosopagnosia? What did the patients know? What can't prosopagnosic patients recognise? How do patients recognise people?Demasio 1982
That a face is a face and can name parts of a face but cannot recognise the face
Famous faces, family, friends, their own face
Other non-facial cues such as hair, gait, clothing - 19Which patient who had anterograde amnesia and achromotopsia also had prosopagnosia? What the patient good at recognising? What couldn't he recognise? Where did the patient have lesions?IE
3D and 2D object however had some difficulty with more obscure objects and silhouettes
Faces, gender, age, impaired deciding if two faces are the same person
Undersurface of occipital lobes bilaterally and to left hippocampus (amnesia), bilateral damage to fusiform face area, left v4 damage Colour, - 20What disorders frequently co-occur? What does this suggest?Agnosia and prosopagnosia
There are patients with intact object recognition and impaired face recognition and vice versa
Different brain regions are dedicated to face and object recognition - 21Evidence for Object and Faces being processed differently: Who was it? What did he do? What did he find? InterpretationBruce et al 1981
Recorded cells in the monkey area inferior temporal to different stimuli such as monkey face, jumbled face and hand (single-cell)
Must responsive to full faces, less when jumbled, less again with hand
Therefore the inferior temporal is preferentially active to faces - 22Evidence for Object and Faces being processed differently: Who was it? What did he do? What did he find?Kanwisher et al 1997
fMRI to measure activity in response to faces compared to objects
Higher activation in the fusiform gyrus for faces - 23Evidence for Object and Faces being processed differently: Who was it? What did he do? What did he find?Ishai et al 1999
Measured activation in medial fusiform gyrus for faces/house/objects
There was greater activation when exposed to faces but there was also activation for objects too, neurons preferentially reacted greater to faces
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- Degree Neuropsychology Flashcards on Visual Agnosias, created by kat.bridgman on 04/05/2015.
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