Vision

Question 1

What are the pre-neural elements of the eye?

Answer 1

Cornea, lens and ocular media

All focus and filter the light before reaching the retina

Question 2

What is light energy converted into ?

Answer 2

electrical signals

Question 3

What does the retina do?

Answer 3

mediates the conversion of light energy to electrical signals

Question 4

Describe the characteristics of Rods

Answer 4

• low spatial resolution
• high sensitivity ( 1 photon)
• dominant at night
• loss of function = night blindness
• less dense
• membrane disks unattached to outer mem

Question 5

Describe the characteristics of cones

Answer 5

• high spatial resolution
• low sensitivity
• less saturation
• rapid recovery
• colour vision, dominant at daylight
  loss of cone = blind
• dense
• membrane disks attached to outer mem

Question 6

What is the first stage in central processing of vision?

Answer 6

5 layers of retina

Question 7

What are the five layers of the retina ?

Answer 7

1. Photoreceptors
2. Bipolar cells
3. ganglion cells
4. Amacrine cells
5. Horizontal cells

Question 8

What is the optic nerve made of ?

Answer 8

retinal ganglion cell axon

Question 9

What happens at the optic chasm ?

Answer 9

partial crossing of optical nerves so the temporal fields cross

Question 10

What information does the pretectal nucleus get?

Answer 10

reflexive eye movements

Question 11

What information does the suprachismatic nucleus get?

Answer 11

sleep-wake cycle

Question 12

What does peripheral vision mean ?

Answer 12

detected by one eye

Question 13

What provides refraction in the eye?

Answer 13

cornea

Question 14

What is accommodation in terms of vision?

Answer 14

changing ur optical power to focus near + far by relaxing and contracting

Question 15

What do oposins do in phototransduction ?

Answer 15

Sit within the mem of disc

Sensitive to particular waves

Question 16

How are signals terminated ?

Answer 16

calcium ion decrease as channels close
cGMP restored
Rhodopsin kinase gets activated and phosphorylated causing transducin displacement

Question 17

How many logs of light intensity are there?

Answer 17

12

Question 18

How do we see in colour?

Answer 18

Colour vision = trichromatic 
3 cones all are monochromatic 
Blue - short 
Green - medium 
Red - long 
comparison of cones to extract colour info

Question 19

What cells detect changes in luminance?

Answer 19

Ganglion cells

Question 20

What are the classes of ganglion cells ?

Answer 20

on-centre (light in receptive field = AP)
off-centre (light turned off = AP)
Equal numbers of both

Question 21

What NT do ganglion cells use?

Answer 21

glutamate