8. Colour opponency

Question 1

Which ganglion cells is for detecting red and green info?

Answer 1

Midget ganglion cell in
Parvocellular pathway.

Red-on/Green-off cells: Excited by red light and inhibited by green light.

Green-on/Red-off cells: Excited by green light and inhibited by red light.

Question 2

Which ganglion cells is for detecting yellow and blue info?

Answer 2

Bistratified ganglion cell in
Koniocellular Pathway

Blue-on/Yellow-off cells: Excited by blue light and inhibited by yellow light.

Yellow-on/Blue-off cells: Excited by yellow light and inhibited by blue light.

Question 3

Which ganglion cells is for detecting light dark info?

Answer 3

Parasol ganglion cell in
Magnocellular pathway

L-on/L-off cells: Non opponent pathway.

Question 4

Which are the colour opponent pathway and which aren’t?

Answer 4

Parvocellular + Koniocellular = colour opponency

Magnocellular = Non colour opponency

Question 5

What does colour opponency suggest?

Answer 5

We never see red and green together, we never see yellow and blue together.

r/g antagonism between L and M cones
b/y antagonism between S and L/M cones.

Question 6

Describe the colour opponency and spectral sensitivity experiment.

Answer 6

1. 2 channel maxwellian view optical system
2. 1 deg test spot / 15 deg white background
3. 1Hz detection thresholds for colour opponency
   25 Hz for non opponent