Visual object and face recognition

Question 1

Explain Milner and Goodale’s reformulation of the ‘what’ and ‘where’ hypothesis for ventral and dorsal stream functions

Answer 1

• Ungerleider and Mishkin suggested in 1982 that the dorsal pathways had a spatial function and the ventral pathways delta with object recognition
• M and G (1992); Perception/action

Question 2

Ventral stream:

Answer 2

vision for perception/object recognition

Question 3

Dorsal stream:

Answer 3

vision for action/spatial awareness

Question 4

Describe the different forms of visual agnosia

Answer 4

• Due to extrastriate visual cortical damage but may be accompanied by partial visual field loss if damage extends to V1
• associated with damage to ventral occipitotemporal cortex (fusiform gyrus)
• failure of visual recognition but preserved visual acuity
  
  • subjects may be able to copy drawings of objects without identifying them
  • can identify by other modalities (sound, tactile)

Question 5

OPTIC ATAXIA

Answer 5

• problem with visually-guided movements (not primarily visual or motor problem)
• acuity, form, colour vision intact
• lesions in parietal areas (dorsal stream)

Question 6

What are face cells and where are they found?

Answer 6

• Face cells reported from recordings in monkey IT cortex since 1970s
• large RFs that usually include fovea and may be bilateral
• less sensitive to precise retinal position, size, contrast, angle
• destination of ventral stream (inferotemporal cortex: IT and subdivisions)

Question 7

Face perception

Answer 7

• Does the mind/brain consist of special-purpose (domain-specific) mechanisms or general purpose (domain-general) mechanisms?
• Face perception is a prime candidate for a domain-specific process

Question 8

Cortical areas in humans

Answer 8

• ventral occipitotemporal cortex including fusiform gyrus
• areas equivalent to large part of inferotemporal cortex in monkeys
• several putative areas
  
  • fusiform face area
  • occipital face area

Question 9

prosopagnosia

Answer 9

-special case of visual agnosia, usually loss of recognition for individual face identity
-mixed with object recognition deficits but sometimes ‘pure’
-co-oocurs with cerebral achromatopsia
-ventral stream

Question 10

Face selective cells

Answer 10

• used fMRI in monkeys to find face-sensitive ‘hot spots’
• determined coordinates to target microelectrode penetrations