4. Vision - LGN to V1

Question 1

involves the lateral geniculate nucleus of the thalamus which projects up to the visual cortex

Answer 1

the geniculo-striate pathway (aka thalamocortical pathway)

Question 2

found in the occipital lobe and lies along the central sulcus

Answer 2

visual cortex

Question 3

does the lateral geniculate nucleus (LGN) project contralaterally or ipsolaterally to the visual cortex?

Answer 3

ipsolaterally

Question 4

why is the visual cortex also called the striate cortex?

Answer 4

because of its striped appearance

Question 5

what happens at the optic chiasm?

Answer 5

axons from retinal ganglion cells on the nasal hemiretina cross over to the contralateral side of the brain

Question 6

axons of the retinal ganglion cells leave the eye as the:

Answer 6

optic nerve

Question 7

axons from the temporal hemiretina project to:

Answer 7

the lateral geniculate nucleus (LGN) on the ipsolateral side of the brain

Question 8

what percent of visual information “crosses over” to the contralateral hemisphere at the optic chiasm?

Answer 8

~55%

Question 9

due to the “crossing over” of visual information in the optic chiasm, the left visual field is represented in the:

Answer 9

right lateral geniculate nucleus (LGN) and the right visual vortex (and vice versa for the right visual field)

Question 10

is there more or less decussation (crossing over) in lateral eyed animals?

Answer 10

more (have much less binocular overlap than frontal eyed animals)

Question 11

how many layers are in the lateral geniculate nucleus (LGN)?

Answer 11

six

Question 12

layers one and two of the LGN are known as the:

Answer 12

magnocellular layers

Question 13

layers two, three, and five of the LGN receive input from the:

Answer 13

ipsolateral eye

Question 14

layers one, four and six of the LGN receive input from the:

Answer 14

contralateral eye

Question 15

layers three, four, five, and six of the LGN are known as the:

Answer 15

parvocellular layers

Question 16

what are the light bands between the layers of the LGN?

Answer 16

konicellular layers

Question 17

adjacent points in the visual field are represented by:

Answer 17

adjacent neurons in the LGN

Question 18

what type of receptive fields are found in the lateral geniculate nucleus (LGN)?

Answer 18

centre-surround receptive fields (same as RGCs)

Question 19

true or false: the parvocellular and magnocellular layers of the LGN receive inputs from different types of RGCs

Answer 19

true

Question 20

the parvocellular layers of the LGN receive inputs from:

Answer 20

“midget” RGCs

Question 21

the magnocellular layers of the LGN receive inputs from:

Answer 21

“parasol” RGCs

Question 22

true or false: like RGCs and the LGN, visual cortical cells also have centre-surround receptive fields

Answer 22

false!

Question 23

what are the three major cell types of the visual cortex?

Answer 23

• simple cells
• complex cells
• end-stopped cells

Question 24

cells which responds to “bars” of light of a particular orientation (orientation selective)

Answer 24

simple cells

Question 25

cells which respond to "bars" of light of a particular orientation, moving in a particular direction (direction selective)

Answer 25

complex cells

Question 26

cells which respond to moving "bars" of light of a particular orientation and a particular length (others like moving "corners")

Answer 26

end-stopped cells

Question 27

go review slide 299

Answer 27

there is just no good way to write that down

Question 28

the cells of the visual cortex are known as:

Answer 28

"edge detectors" (in a scene, we identify where the edges are before anything else)

Question 29

how did Hubel and Wiesel build a simple cell receptive field from surround-centre receptive fields of LGN neurons?

Answer 29

receptive fields of LGN neurons overlap with one another and the summation of them creates an oval shape with a "bar" in the centre

Question 30

how did Hubel and Wiesel build a complex cell receptive field?

Answer 30

summation of the inputs from simple cells

Question 31

how did Hubel and Wiesel build an end-stopped cell receptive field from receptive fields of complex cells?

Answer 31

adjacent complex cells can be excitatory or inhibitory, and the summation of these inputs will either excite or inhibit the neuron

Question 32

go review slide 304

Answer 32

this one is good i promise

Question 33

how many layers are in the visual cortex?

Answer 33

six (however, layer four is split into 4a, 4b, and 4c)

Question 34

where do inputs enter the visual cortex?

Answer 34

usually layer 4

Question 35

where do layers 5 and 6 of the visual cortex project to?

Answer 35

other parts of the brain

Question 36

where in the visual cortex are simple cells found?

Answer 36

layers 4 and 6

Question 37

where in the visual cortex are complex and end-stopped cells found?

Answer 37

layers 2, 3, 5, and sometimes 6

Question 38

where do cells of the konicellular pathway (LGN) project to?

Answer 38

layers 4a, 2, and 3 of the visual cortex

Question 39

where do cells of the magnocellular pathway (LGN) project to?

Answer 39

layers 4b and 4c of the visual cortex

Question 40

where do cells of the parvocellular pathway (LGN) project to?

Answer 40

layers 2, 3, 4a, and 4c

Question 41

true or false: center-surround cells can be found in the visual cortex

Answer 41

true! (in layer 4)

Question 42

layers 2, 3, and 4b of the visual cortex project to:

Answer 42

other areas of the cortex

Question 43

layers 5 and 6 of the visual cortex project to:

Answer 43

deep brain structures as well as other cortical areas