Visual Part 3 Flashcards
Does light inhibit or enhance glutamate release from rods/cones?
light inhibits glutamate release
What happens when light hits the center of the receptive field?
decreased glutamate released from the cone, which cause ON bipolar cells to depolarize and excite the ganglionic cell. the decrease glutamate release also inhibits OFF bipolar cells
What happens when there is not light at the center of the RF?
photoreceptors release more glutamate, activating OFF bipolar cells which activate the OFF ganglion
Is the retinal response to darkness active or inactive?
active
What kinds of ganglion cells respond to light spots surrounded by dark backgrounds? (eg, stars in the sky)
ON-center retinal ganglions
What kinds of ganglion cells respond to darks spots surrounded by light backgrounds? (eg. a fly in a bright sky)
OFF-center retinal ganglions
What is lateral inhibition?
Light in surrounding fields inhibit bipolar cells and ganglion cells, even if there is darkness in the center that might activate the bipolar and ganglion cells
How does lateral inhibition work on ON and OFF cells when light is shined on surrounding areas?
OFF cells in the surrounding area are stimulated. ON cells in the center are inhibited
What does the rate of activity of ganglion cells indicate?
The amount of contrast between the center and the receptive field
Why is it that a moderately bright region can appear brighter or darker depending on its background?
Because the ganglion cells enhance the contrast
How do ganglion cells code color?
They are inhibited/excited by some and not other colors. = Reciprocal excitation-inhibition
