Extrastriate Visual Cortices

Question 1

Where does separation of function start in the visual system? Describe it.

Answer 1

• starts at the retina
• parvo vs magnocellular layers receive inputs from different types of RGCs (midget and parasol)

Question 2

TRUE or FALSE: RGCs with a large dendritic tree tend to be found int he periphery, whereas small trees are found in the fovea.

Answer 2

TRUE

Question 3

TRUE or FALSE: P cells are more specialized for motion, whereas M cells are more specialized for form.

Answer 3

FALSE: P cells = form, M cells = motion

Question 4

TRUE or FALSE: midget cells have small receptive fields and parasol cells have large receptive fields

Answer 4

TRUE

Question 5

TRUE or fALSE: midget cells have a transient response and parasol cells have sustained response.

Answer 5

FALSE: midget = sustained; parasol = transient

Question 6

TRUE or fALSE: P cells have low temporal resolution and M cells have high temporal resolution

Answer 6

TRUE

Question 7

TRUE or FALSE: destruction of the parvocellular layers in the LGN result in loss of motion vision.

Answer 7

FALSE: loss of form

hint: midget cells

Question 8

TRUE or FALSE: destruction of the magnocellular layers in the LGN result in loss of motion vision

Answer 8

TRUE

Question 9

what enzyme is marker for colour blobs?

Answer 9

cytochrome oxidase

Question 10

How does cytochrome oxidase appear in V1 vs V2?

Answer 10

• V1 = blobs
• V2 = stripes (thick, thin, pale)

Question 11

From where do thin stripes in V2 receive their input? thick stripes? pale stripes?

Answer 11

• thin stripes receive from V1
• thick and pale stripes receive from interblobs

Question 12

What aspect or vision do thick, pale, and thin stripes mediate?

Answer 12

• thick = motion
• pale = form
• thin = colour

Question 13

Which stream/cortical lobe is concerned with motion? colour and form?

Answer 13

• motion = dorsal/parietal stream
• colour and form = ventral/temporal stream

Question 14

Draw a flow chart of information flow from the retina to the association cortex in the visual parietal/ventral stream. Which types RGCs are involved?

Answer 14

slide 9

Question 15

What functions are visual stimuli mainly separated into?

Answer 15

form, motion, colour

Question 16

Which area of the brain is specialized for processing motion?

Answer 16

middle temporal cortex (MT)

Question 17

How does microstimulation of certain neurons in the MT affect vision?

Answer 17

cause a bias towards certain direction of motion

Question 18

Which are of the brain is specialized for processing the optic flow of motion?

Answer 18

medial superior temporal cortex (MST)

Question 19

TRUE or FALSE: MT neuron receptive fields area larger than MST neuron receptive fields.

Answer 19

FALSE: MST receptive field larger

Question 20

Which part of the brain is specialized for form?

Answer 20

ventral temporal stream

Question 21

Which part of the brain do simple lines activate? complex form?

Answer 21

• simple lines activate central occipital lobe (V1)
• complex forms activate the inferotemporal lobe

Question 22

TRUE or FALSE: IT cortex demonstrates columnal organization in terms of complex form processing.

Answer 22

TRUE

Question 23

Which visual stream is responsive to faces?

Answer 23

temporal stream

Question 24

TRUE or FALSE: cells in the temporal stream respond not only to faces but also apples and clocks.

Answer 24

TRUE: although very small response…maybe because round?

Question 25

Which structure of the brain is activated when you perceive two faces? a vase?

Answer 25

- faces = fusiform face area (FFA) - vase = inferotemporal lobe (IT)

Question 26

What is the parahippocampal place area (PPA) specialized for in vision? What are its preferred stimuli?

Answer 26

spatial memory; stimuli = landscapes, locations, etc.

Question 27

What is the extrastriate body area (EBA) specialized for in vision?

Answer 27

body parts (that are not faces)

Question 28

TRUE or FALSE: the temporal cortex's specialization in vision cannot be modified.

Answer 28

FALSE: can be modified by EXPERIENCE

Question 29

TRUE or FALSE: bird experts showed more activation in the FFA than car experts in response to faces.

Answer 29

TRUE