L19 Retina

Question 1

What do horizontal cells do?

Answer 1

• Provide long and local range interactions between photoreceptors
• Adjust the gain of photoreceptic synaptic output (modulated transmitted signal)
• They generate spatial opponency (detection of two distinct signals in space) in both cones and bipolar cells.

Question 2

What are the 3 types of Horizontal cells in humans?

Answer 2

HI -> its dendrites connect with cones and the axons with rods
HII -> connects with cones, mainly blue
HIII –> connects with red and green cones, still unknown cell type connected with the HIII axon.

Question 3

Bipolar cells:

Answer 3

Important in the “through” pathway (information from photoreceptor to bipolar to ganglion cells).

10 types: Rod bipolar cells, 9x cone bipolar cells
ON bipolar cells: depolarise to light, synapse in the inner half of IPL
OFF bipolar cells: hyperpolarise to light, synpase in the outer half of IPL.