The Eye (II)

Question 1

What allows interaction between outputs in retina

Answer 1

Horizontal and amacrine cells

Question 2

True or false. Many rods can converge to a single bipolar cell to increase light sensitivity

Answer 2

True

Question 3

True or false. It is only 1 bipolar cell which attaches to ganglion cell

Answer 3

False. Many bipolar cells can converge

Question 4

Where do AP first appear

Answer 4

Ganglion cell (rest is graded potentials)

Question 5

Are bipolar cells always excited by glutamate (in dark)

Answer 5

No, some are inhibited by glutamate release in dark so are active in light

Question 6

What does a ganglion cell receptive field mean

Answer 6

Area of retina which excites the ganglion cell

Question 7

What is the receptive field of ganglion cells called

Answer 7

Centre surround organisation

Question 8

Explain centre surround organisation

Answer 8

Two types of ganglion cell

On centre/off surround

Off centre/on surround

Question 9

What does on centre off surround mean

Answer 9

Excitation via light on the centre of ganglion causes AP

Inhibition due to light on the surround, responds to dark more

Question 10

Why is the AP weak of light is shone to ganglion cell whole of it

Answer 10

Because it excites one but inhibits the other

Contrast is better where dark is at the inhibitory site and light at excitatory

Question 11

What process allows edges to be defined at ganglion cells

Answer 11

Lateral inhibition

Question 12

Which organisation do cone ganglion cells have and what are the 2 types

Answer 12

Centre surround organisation

Red(long wavelength) - green (medium wavelength) : one excites one inhibits

Blue (short wavelength) - yellow (mix of long and medium green and red)

Question 13

What would happen if white light with red and green wavelengths was shone onto cone red green ganglion cell

Answer 13

Weak excitation

Red would stimulate but green would inhibit

Question 14

Where does info cross over from the optic fibre

Answer 14

Optic chiasm

Question 15

Which fibres cross over in chiasm

Answer 15

One from each nasal retina

Question 16

Where do fibres from right eye go from chiasm

Answer 16

Right lateral geniculate body (thalamus)

Question 17

Where does info go from right lateral geniculate body for the left eye go

Answer 17

Left visual cortex

Question 18

Where is the visual cortex

Answer 18

Occipital lobe

Question 19

Which receptive field do neurones in lateral geniculate body have

Answer 19

Centre surround organisation

Question 20

How are neurones at visual cortex more specific for stimulation/ receptive field

Answer 20

Prefer bars not dots

Need to be in correct position for stimulus

Need to be in right orientation for stimulus

Question 21

Do neurones in visual cortex prefer moving objects

Answer 21

Yes

Question 22

What are the neurones for specific position or orientation calls

Answer 22

Position - simple

Orientation - complex

Question 23

What are the 2 pathways info goes down in visual cortex

Answer 23

Dorsal stream - action pathway

Ventral stream - recognition pathway

Question 24

What does dorsal stream action pathway do

Answer 24

Decide how to act on stimulus / light

Question 25

What does ventral recognition pathway do

Answer 25

Detect edges and shape to identify object