seminar 6 - claudia racca

Question 1

the striate cortex is organised in ocular dominance columns alternating between…

Answer 1

left and right eye

Question 2

which layer in V1 is split into column

Answer 2

layer 4C

Question 3

the cells in layer 4C are monocular meaning..

Answer 3

they see information from only one eye (because of the column)

Question 4

cells in V1 are each wired up to a..

Answer 4

photoreceptor in a particular region of the retina

Question 5

nearby photoreceptors are connected to nearby…

Answer 5

neurons

Question 6

primary visual cortex maintains the topographic mapping of the visual world.
more cortical area is devoted to which part of vision

Answer 6

the fovea (center)

Question 7

neurons in the visual cortex have more selective responses than ganglion cells and lateral geniculate neurons. for example…

Answer 7

• can detect bars and edges, not spots
• the specific position of stimulus in receptive field
• the specific orientation
• the specific direction

Question 8

receptive fields of layer 4C neurons are similar to LGN neurons but layers outside 4C have receptive fields with…

Answer 8

new characteristics

Question 9

what does binocularity mean

Answer 9

in V1 inputs from left and eyes are combined

Question 10

in layer 4, inputs come predominantly from one or the other eye. this is called

Answer 10

monocular

Question 11

outside layer 4 neurons have two receptive fields, one in ipsilateral eye and one in the

Answer 11

contralateral eye.

Question 12

there is input from the left and right eye into layer 4C. layer 4C will project to other layers (e.g layer 3) where the cells receive _________ input

Answer 12

binocular

Question 13

which layer in 4c is insensitive to the wavelength

Answer 13

4calpha

Question 14

which layer in 4c has center surround colour opponency

Answer 14

4cbeta

Question 15

outside layer 4c in v1 we find oriented receptive fields for the first time. what does this mean

Answer 15

cells no longer respond best to circular spots of light but to elongated bars of light moving across the receptive field. these neurons exhibit orientation selectivity (responds to specific angle of the bar)

Question 16

cells with similar orientation preferences lie in the same…

Answer 16

column

Question 17

some of the neurons that are orientation selective are also….

Answer 17

direction selective

Question 18

receptive fields in V1 cells can be simple or complex.
simple responds to…

Answer 18

bars of light with a specific orientation

Question 19

complex responds to….

Answer 19

a moving light stimulus of a particular orientation and direction of travel

Question 20

simple cells

Answer 20

sum of inputs from LGN neurons with neighbouring/aligned receptive fields build an elongated receptive field that is most responsive to elongated bars or edges
and simple cells are most responsive to a specific orientation of the bar

Question 21

complex cells

Answer 21

• receive input from simple cells
• orientation selective
• no ON/OFF subregions
• nearly all binocular
• perform length summation

Question 22

hypercomplex cells

Answer 22

like complex cells with inhibitory flanks on the end of the receptive field
response increase with increasing bar length up to a limit and the response is inhibited

Question 23

simple, complex and hypercomplex cells can work together to decompose the outlines of a visual image into short segments. this is the basis on simple and complex object recognition

Question 24

what is a hypercolumn

Answer 24

a set of columns responsive to lines of all orientations from a particular region in the visual fields and viewed by both eyes