045 Vision

Question 1

Which cells are the only cells in the eye that produce action potentials?

Answer 1

Ganglion cells

Question 2

What do amacrine cells do?

Answer 2

Processing and optimising retinal circuitary
Makes contact with bipolar cells, ganglion cells and other amacrine cells via dendritic process in the IPL
Light exposure causes dopamine release, enhancing contrast sensitivity.
Helps adaptation to daylight conditions.

Question 3

Where is the mGluR6 receptor located? and how does glutamate effect this receptor?

Answer 3

Located on ON bipolar cone and rod cells. Glutamate will inhibit these receptors.

Question 4

Which receptors are found on OFF bipolar cells and what effect does glutamate have?

Answer 4

Kainate/ AMPA receptors. Glutamate will excite this

Question 5

How does scotopic vision occur?

Answer 5

1. ON bipolar cells will synapse with amacrine cells, which are inhibitory.
2. Amacrine cells will inhibit OFF pathways via synapses
3. They will also excite cone bipolar ON pathways.

Question 6

What occurs during surround illumination and center is dark to the horizontal cells.

Answer 6

1. Surround illumination causes hyperpolarisation
2. Less excitation of horizontal cells
3. Less GABA inhibition by horizontal cells onto photoreceptors.
4. More glutamate release by horizontal cells
5. More hyperpolarisation of ON bipolar cells and more depolarisation of OFF bipolar cells.

Question 7

What are magnocellular ganglion cells for?

Answer 7

Light and movement detection -> large receptive field.

Question 8

What are parvocellular ganglion cells for?

Answer 8

Color detection -> small receptive field