Vision Flashcards
(102 cards)
Discuss sensation vs perception
Sensation: Involves cells of the NS that are sensitive to their environment
Perception: the conscious experience and interpretation of information
Hue?
- Wavelength of light
- What we perceive as colour
- Determined by length
Brightness?
- Intensity of light
- Determined by amplitude
Saturation?
-Relative purity of light
Electromagnetic spectrum of visible light?
400-700 nm, from blue (higher energy, shorter wavelength to red, lower energy and larger wavelength)
How is information from SR in the eye transmitted to the brain?
Through sensory transduction
How do we see?
By focusing an image on our retina, helped by the extraocular muscles attached to eyes
What regulates the amount of light entering our eyes?
Iris
What focuses the entrance of light into the eye?
The Cornea
What are the 3 celllular layers of the retina?
- Photoreceptors (cones/rods)
- Bipolar
- Ganglion
What is the fovea? Where is it located? what does it allow for?
- Region of the retina which allows for the most acuity of vision as it exposes cones only (other layers pushed away)
- Allows for better acuity and colour processing
(T/F) there are more cones than rods in the retina
F, there are more rods
What is the optic disk?
Place in the retina where there are no PR, therefore the blind spot
Discuss 4 key characteristics of cones
- Most prevalent in the central retina (fovea)
- Sensitive to mod/high light
- Provide info about hue
- Provide acuity
Discuss 4 key characteristics of rods
- Most prevalent in the peripheral retina, NOT found on the fovea
- Sensitive to low levels of light
- Provide monochromatic information only
- Provides poor acuity
What are the two other cells in the retina layers?
- Horizontal cells
- Amacrine cells
Discuss horizontal cells
Connect adjacent PR and the neuroprocesses of bipolar cells
Discuss amacrine cells
Connected to ganglion cells and the neuro processes of bipolar cells, transmitting information from BP –> GC cells
Name the two theories of perception of colour in the retina
1) Trichromatic coding
2) Opponent-Process coding
Discuss trichromatic coding in the retina
In TC, the eye will detect different colours b/c it contains three different types of receptors.
What are the three types of receptors in TC?
1) Short wave CR=blue
2) Medium wave CR=green 3) large wave CR= Red
- All of these are opsin receptors
If there is a defect in the CR, according to TC, what are the three types of genetic defects of colour? (PDMT)
- Protanopia
- Deutranopia
- Tritanopia
- Monochromatic vision
What is protanopia?
Difficulty seeing red, red cones filled with green opsin
What is deuteranopia?
Difficulty seeing green, green cones filled with red opsin