The Eye (II) Flashcards Preview

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Flashcards in The Eye (II) Deck (25)
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1
Q

What allows interaction between outputs in retina

A

Horizontal and amacrine cells

2
Q

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

A

True

3
Q

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

A

False. Many bipolar cells can converge

4
Q

Where do AP first appear

A

Ganglion cell (rest is graded potentials)

5
Q

Are bipolar cells always excited by glutamate (in dark)

A

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

6
Q

What does a ganglion cell receptive field mean

A

Area of retina which excites the ganglion cell

7
Q

What is the receptive field of ganglion cells called

A

Centre surround organisation

8
Q

Explain centre surround organisation

A

Two types of ganglion cell

On centre/off surround

Off centre/on surround

9
Q

What does on centre off surround mean

A

Excitation via light on the centre of ganglion causes AP

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

10
Q

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

A

Because it excites one but inhibits the other

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

11
Q

What process allows edges to be defined at ganglion cells

A

Lateral inhibition

12
Q

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

A

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)

13
Q

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

A

Weak excitation

Red would stimulate but green would inhibit

14
Q

Where does info cross over from the optic fibre

A

Optic chiasm

15
Q

Which fibres cross over in chiasm

A

One from each nasal retina

16
Q

Where do fibres from right eye go from chiasm

A

Right lateral geniculate body (thalamus)

17
Q

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

A

Left visual cortex

18
Q

Where is the visual cortex

A

Occipital lobe

19
Q

Which receptive field do neurones in lateral geniculate body have

A

Centre surround organisation

20
Q

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

A

Prefer bars not dots

Need to be in correct position for stimulus

Need to be in right orientation for stimulus

21
Q

Do neurones in visual cortex prefer moving objects

A

Yes

22
Q

What are the neurones for specific position or orientation calls

A

Position - simple

Orientation - complex

23
Q

What are the 2 pathways info goes down in visual cortex

A

Dorsal stream - action pathway

Ventral stream - recognition pathway

24
Q

What does dorsal stream action pathway do

A

Decide how to act on stimulus / light

25
Q

What does ventral recognition pathway do

A

Detect edges and shape to identify object