organisation of the visual system

Question 1

Felleman and Essen, 1991? (2 visual systems)

Answer 1

identified different modules within the visual brain and looked at structural differences.

• how V1 is structured, showed projections from different layers within the striate cortex, identified different routes coming from the superior colliculus:
• SC-temporal lobe (object recognition)
• SC- parietal lobe (object orientation)

Question 2

Pegna 2005? (blindsight)

Answer 2

blindsight patients showed sensitivity to fearful expressions of peoples’ faces.

Question 3

DeGalder 2008? (blindsight)

Answer 3

asked blindsight patients to make routes around strews of obstacles without a stick as a guide
- they could successfully do it and avoid obstacles highly efficiently
…have enough vis info to get into system to make a perceptual decision, even tho their V1 is destroyed so they cannot see.

Question 4

Amedi, Israelian lab and LOC?

Answer 4

found that the lateral occipital cortex (LOC) selectively activated when viewing objects

Question 5

Justine Sergent?

Answer 5

she discovered the fusiform face area (FFA) and prosopagnosia/ damage to FFA leads to an ability to recognise faces

Question 6

Malach, 1995 and LOC?

Answer 6

LOC responds only to images of objects, and not to depth or motion.

Question 7

Amedi and Malach, 2002? (LOC)

Answer 7

is LOC a visual object region?
-handed ppl objects that were familiar to them but could not see them.
- found that haptic exploration of the object activated LOC.
therefore the LOC is a shape perception and not visual…feeling pen activates LOC without seeing it, and seeing the pen also activates LOC…so regions overlap!

Question 8

Downing, Kanwisher and Jiang in 2001? (EBA)

Answer 8

EBA/ extra-striate body area selectively responds to body parts/bodies/silhouettes of bodies

• faces do not activate EBA and get shunted to the FFA
• EBA is beside LOC (object recognition/shape perception)

Question 9

VWFA study on adults learning to read?

Answer 9

VWFA= visual word form area/ selectively responds to words and letters…NFA/ number form area responds to digits
- emerging VWFA takes over the FFA in children learning to read and in adults learning to read later in life!
- adults learning to read later in life have superior facial recognition!
…amount of real estate dedicated to any function=directly correlated with performance

Question 10

Amedi 2013, and braille readers?

Answer 10

if congenitally blind people read letters through touch (Braille), was sufficient enough to activate the VWFA.
…exact same regions in sighted people are activated in blind people.

Question 11

study on auditory effects in visual system in blind people?

Answer 11

when blind people listen to sentences- verbs/action words activate the VWFA and V1.
…auditory effects in visual part of brain, showed activation to words and actions despite not being able to see words or actions.

Question 12

Amedi 2007? (sensory substitution device)

Answer 12

LOC was activated when hearing the shape of an object
sound doesn’t encode shape, but we can use frequency to infer shape and this is sufficient to activate LOC in blind individuals (hearing the object shape through visual images being converted to sound frequencies in LOC)

Question 13

Striem-Amit and Amedi, 2014? (EBA activation in blind)

Answer 13

sensory substitution sounds of body shapes activated the EBA in blind people
EBA shows anatomical consistency in early blind, and exists regardless of visual experience or body expertise.

Question 14

Kitada 2014? (object recognition in blind)

Answer 14

blind people learned to recognise objects using haptics only
an fMRI showed that the EBA was activated in blind using haptic recognition on hand gestures only (shaking hand, high 5 etc)
- such activation overlapped with that of sighted people to visual images of hand gestures.