sight

Question 1

phototransduction cascade

Answer 1

Rods have rhodophsin which is turned on when lights do not hit them.
Inside the rhodopshin is retinal, and when light hits, it changes conformation causing rhodopsin to change shape.
1. This cause transducin to be released from rhodophsin and alphs part comes to disk and binds to phosphodiesterase (PDE) ( which is responsible for converting cGMP to GMP)
2. GMP closes Na channels –> deactivating or turning off, cGMP opens Na channels –> turning on cell.
3. But, in this case cGMP turns into GMP
4. This turns off rods and turns on the center of bipolar cells.
5. This activates retinal ganglion cells which sends a signal to optic nerve to brain.

Question 2

Differences between Rods and cones

Answer 2

1. There are 120 M rods vs. 6 million cones
2. Cones are concnetrated in the fovea while rods are found in the periphery
3. Rods are more sensitive thatn cones, so better at detecting light.
4. cones are less sensitive but detect color ( 60% Red, 30% Green, 10% Blue).
5. Rods have slow recovery time, cones have fast recovery time.

Question 3

Spatial resolution

Answer 3

boundaries and shape, high level of details. Form

Question 4

Temproal resolution

Answer 4

Detects motion

Question 5

Feature detection

Answer 5

color ( trichromatic theory of color vision), Form ( parvocelluar theory - good at spatial resolution, but poor temporal resolution), motion ( magnocellular pathway - has high temporal resolution and poor spatial resolution, no colour)
see one thing at a time: break down the components of colour, form, and motion

Question 6

Parallel processing

Answer 6

see all the three components of visualization, form, motion, and colour at the same time.