Lecture 33. The Eye and Vision

Question 1

What range of light can the eye see?

Answer 1

Can detect light over a dynamic range of more than 100 million to 1 (bright sunlight to faint starlight)

Question 2

Why is vision not static?

Answer 2

The eye scans the subject to bring the image into the fovea

Question 3

What is the human retina equivalent to?

Answer 3

576 megapixels

Question 4

What happens to photoreceptors in the dark?

Answer 4

Depolarise

Question 5

What is the receptive field?

Answer 5

If many sensory receptor cells converge and form synapses with a single neuron, they collectively form the receptive field of that cell

Question 6

What do ganglion cells contain?

Answer 6

Concentric receptive fields

Question 7

What do on-centre ganglion cells signal?

Answer 7

Rapid increases in light intensity

Question 8

What do off-centre ganglion cells signal?

Answer 8

Rapid decreases in light intensity

Question 9

What does the M channel analyse?

Answer 9

Movement

Question 10

What does the P channel analyse?

Answer 10

Fine detail and colour

Question 11

Besides rods and cones what is the other photoreceptor in the retina?

Answer 11

Light sensitive ganglion cells (ipRGC)

Question 12

What is melanopsin?

Answer 12

Ancient opsin in the ipRGC

Question 13

What arethe roles of ipRGCs?

Answer 13

Low acuity images
Pupillary dilation
Circadian clock entrainment