agnosias and apraxias

Question 1

occipital lobe- medial surface

Answer 1

parieto-occipital surface –> calcarine sulcus

• contains much of visual cortex (V1)
• seperates upper/lower visual fields

Question 2

occipital lobe- ventral surface

Answer 2

lingual gyrus (v2) and fusiform gyrus (V4)

Question 3

visual cortex connections

Answer 3

V1: input from LGN and output to other levels
V2: output to other levels

Question 4

3 visual paths after V2

Answer 4

1. output to parietal lobe (dorsal stream)
2. output to inferior temporal lobe (ventral stream)
3. multimodal output to the superior temporal sulcus (STS)

Question 5

purposes of visual pathways

Answer 5

dorsal- visual guidance of movements/action
ventral- identify objects
- IT inferior temporal cortex for object perception
- STS superior temporal sulcus for visualspatial functions

Question 6

color form and dynamic form processing

Answer 6

ventral stream- V3 dynamic V4 color

Question 7

motion and form processing

Answer 7

dorsal stream- V5 motion V4A form

Question 8

visual deficits

Answer 8

V4: loss of color
V4: loss of motion –> akinetopsia
V3 (also V4): loss of form
V1: cortical blindness

Question 9

genetic deficits in color vision

Answer 9

protanopsia: red cones filled with green –> confusion b/w red and green
deuternopia: green cones filled with red , mostly see red
tritanopia: lack blue cones, only seen in red and greens

Question 10

agnosia

Answer 10

failure of recognition despite sensory receptors working fine

Question 11

disconnection model

Answer 11

visual perception =/= verbal processes

Question 12

stage model

Answer 12

sensory input–> apperception–> percept–> association–> stored info from prev experience

Question 13

computational models

Answer 13

stored representation:

• primal sketch: mental representation of object
• viewer centered: where we are in relation to object
• object centered: regardless of object orientation

Question 14

visual agnosia

Answer 14

apperceptive: can see but cannot recognize
- cannot match or copy
- cannot perceive more than one object at a time
- bilateral damage to lateral parts of occipital lobe (CO2)
associative: inability to recognize an object despite perception
- can copy drawing but not identify it
- lesion higher in processing, anterior temporal lobe

Question 15

simultagnosia

Answer 15

symtpom of apperceptive agnosia

ex. picnic, person tells you bread, wine, water but not percept of picnic

Question 16

H1: modality specific

Answer 16

we have semantic system associated with visual, auditory and tactile processing

Question 17

H2: anatomically specific

Answer 17

semantic system located in deeper parts of brain depending on kind of information we process
ex. closer to somatosensory, auditory can access because no damage–> patients with auditory agnosia cant recognize sounds but can tell you what noise a cow makes

Question 18

cerebral achromatopsia

Answer 18

Inferior surface of temporal occipital region in lingual and fusiform gyri
- V4

Question 19

color agnosia

Answer 19

similar to cerebral achromatopsia but cannot access percept

- unsure of location

Question 20

cerebral akinotopsia

Answer 20

cannot see movement- posterior middle temporal gyrus