L11 - Retina 3 Parallel Pathways

Question 1

CASE STUDY: Monica

• 65 year old
• Saw water splashing in front of her left eye
• Flickering lights
• Grade 3 Melanoma excised 4 years ago

What’s her problem?

Answer 1

Melanoma Associated Retinopathy - antibodies produced targeting against ON BP (mGluR6 or TRPM1 channels) and loses ON BP function

• Patient loses B-wave
• Patient treated with oral prednisolone

Question 2

Where does splitting of information occur first?

Answer 2

At the first synapse (Ph->BCs)

Question 3

Two types of GC

Answer 3

M-GC (5-10% of all GC): motion, LARGE receptive fields -> low spatial res
P-GC: colour, visual acuity, small receptive fields -> high spatial res

Question 4

iGluR are excit/inhibit? mGluR6 are excit/inhibit?

Answer 4

iGluR - excit

mGluR6 (only found in retina) - inhibit

Question 5

OFF cells are de/hyperpol by light? What R?

Answer 5

Hyper, AMPA/Kainate

Question 6

ON cells are de/hyperpol by light? What R?

Answer 6

De, mGluR6

Question 7

What is the difference when comparing the synapses of Ph -> BPs and BP->GCs?

Answer 7

BP-> GC ONLY uses iGluRs (NMDA, AMPA, Kainate)

Question 8

What channel is important in ON BP?

Answer 8

TRPM1 (transient receptor potential melanocyte) channel

Question 9

Receptive field of GC has a centre and an antagonistic surround. What does this mean?

Answer 9

Centre of GC does one thing, surround does opposite

Question 10

What creates the “surround” response?

Answer 10

Horizontal cells

Question 11

Why are edges so important to GC?

Answer 11

Red and green GC communicate edges to the brain - they only fire when there are edges present

Question 12

Melanoma Associated Retinopathy

Answer 12

Antibodies produced targeting against ON BP (mGluR6 or TRPM1 channels) and loses ON BP function

• Patient loses B-wave
• Patient treated with oral prednisolone