Class_04_Perception, and Visuospatial Processing and Action Flashcards
(50 cards)
Prosopagnosia
Impairments of face recognition
- Fusiform Face Area (both; right is bigger)
- can be both apperceptive and associative forms
Associative Prosopagnosia
- cannot name photographs of famous people or say what their occupations
- good at sorting famous faces (which he had seen before) from faces of strangers
- process the faces to a high level, to be able to know which were famous and which were not
Apperceptive Prosopagnosia
- Ventral visual pathway damage
- bad at array tests
- does not require classification
- bad detection of faces
Array Tests
detect face recognition problems
- whether or not a face is present
Alexia
“Acquired” disorder of reading
- Visual Word Form Area of left ventral stream damage (of
right-handed people)
- difficulty recognizing whole words
- can recognize non-word stimuli
- can read individual letters
Hemisphere of Language Processing
Left hemisphere of right-handed people
- The situation is more complicated, and less well understood, in left-handed people
Associative Agnosia
Impairment of the later, abstract, levels of perceptual processing
- pure alexia
Pure Alexia
Understand language
- can write
- cannot read words
- can letter-by-letter read
Phoneme-Grapheme Conversion
Letter-by-letter reading
- phonemes = sounds
- graphemes = written letters
- “C” - “A” - “T” - “CAT”
Phoneme-Grapheme Conversion Problem in Pure Alexia
- “D” - “U” - “M” - “B” - “DUM”
- “B” sound is silent
Posterior Cortical Atrophy
- A variant of Alzheimer’s disease
- Posterior parts of the brain
- the visual processing regions
- make errors on pseudowords
- difficulty recognizing individual letters
-> Apperceptive alexia
Left Ventral Pathway Damage
Visual Word Form Area
- Stroke at left posterior cerebral artery
-> Alexia
Right Ventral Pathway Damage
Fusiform Face Area
- Stroke at right posterior cerebral artery
-> Prosopagnosia
How do people read words
in their left visual field?
- Processed word images in their right hemisphere
- Splenium of corpus collosum
- Passed to the left hemisphere Visual Word Form Area
- recognition
Hemialexia
Cannot read characters shown to the left visual field
- Damage to the splenium of the Corpus callosum
Neuronal Recycling Hypothesis
The Visual Word Form Area may have ‘TAKEN OVER’ an area that used to be for face recognition (i.e., the
left hemisphere Fusiform Face Area).
- Recent brain imaging evidence does not support that theory
How rare is visual agnosia?
20 out of 31 patients (65%)
- Not rare but clinicians test for symptoms not cognitive functions underlying it
Disorders with similarities to visual agnosia
- Optic aphasia
- Semantic dementia
Optic Aphasia
RECOGNIZE visually-presented objects = have knowledge of meaning
- but CANNOT NAME them = can’t find the name for the object
- can sort pictures into categories
- very rare and difficult to identify disorder
Case J.F.
- could name objects by touch, or sound
- but not by vision
- could demonstrate his understanding of what he saw, by PANTOMIMING its use
- can’t name the object that is demonstrated
- didn’t have a general linguistic problem
- could communicate normally
- could answer questions intelligently
Pantomiming
Demonstrate how patients would use objects
- e.g. boots
Associative Agnosia Vs. Optic Aphasia
- Associative Agnosia
- vision -/-> meaning - Optic Aphasia
- vision -> meaning -/-> finding name
- touch/sound -> meaning -> finding name
Semantic Dementia
Lose their knowledge of concepts
- temporal lobe progressive degeneration and thinning
- frontotemporal dementia
- have aphasia
- can’t name objects to visual presentation or other modalities
Pyramids and Palm Trees Test
Test semantic impairments
- Pictures
- Words
