Visual System Flashcards
Wavelength of light determaines what?
color
Intensity of light determines what?
Brightness
The pupil changes shape for what?
Sensitivity and Acuity
What two things make up the convex lens of the eye?
Cornea and Lens
What do the ciliary muscles do? What is this process called?
Shape the lens to fix light on the retina in a process called accommodation
Remember that the cornea is fixed in shape
Shape of the lens for far objects
flat
Shape of the retina for near objects
bent
Binocular Disparity
Discovering the position of an object by seeing the difference in the object’s position in the varying points in both eyes
5 cell types from bottom to top of the retina
- Receptors
- Horizontal cells
- Bipolar
- Amacrine
- Retinal ganglion
What is visual completeion?
Filling in blind spots by interpreting the info surrounding the blind spot
What cell types exclusively comprises the fovea?
Cones
Duplex theory of vision
Rods and cones serve two different kinds of vision
Rod cells function
high sensitivity, low acuity, not color (nighttime focused)
Cone cells function
low sensitivity, high acuity, color (daytime focused)
Three types of cones based on photonic level
Red (long wavelengths)
Green (mid-range wavelengths)
Blue (short wavelengths)
Component (trichromatic) theory
Color is seen by the level of activity in the three cone types
Opponent-process theory
Color is seen by contrasts between opposing colors
If the fovea is so small, why do we not see so little?
Eye movement
How does visual transaction work in the rods?
In the light, light bleaches the sodium channels which hyper polarizes the rod cells and causes little glutamate to be released. In the dark, the opposite process occurs.
How do retinal ganglion cells create a stronger signal?
Push-pull
When light shines near the center of the cell, it is activated, but when in the periphery, it is not activated, but the both cases the cells undergo a process. Both off and on carry meaning. This is called center-surround.
When glutamate is not relayed, the off ganglion likes this and fire, when glutamate is relayed, the on ganglion cells likes this and fires – this is how visual signals get translated to the brain.
What path does info from the visual field follow to the primary visual cortex?
Left field of both eyes combine at the optic chiasm and go to the right primary visual cortex, and vice versa.
Where is the Lateral Geniculate Nucleus?
Thalamus
P cells
Top 4 layers
Detail and stills
Cones
Color
Parvocellular path (what)
M cells
large
bottom 2 layers
no color
motion
rods
magnocellular path (where)
