4-Vision Flashcards
Range of wavelengths of light that humans can see
360nm (~400nm)
to
750nm (~800nm)
Which mammals have colour vision?
Primates
Which traits of light waves correspond to hue, brightness or saturation?
Wavelength/Frequency: hue
Amplitude: brightness
Purity: saturation
Eye anatomy
label diagram “Eye anatomy - 1”
- Iris
- Cornea
- Pupil
- Sclera
- Lens
- Retina
In what orientation does an image land on the retina?
Upside down
and
Reversed left to right
Which part of the eye controls light intake?
the muscles of the iris controlling the pupil size
larger pupil –> more light
Which part of the eye allows us to focus on objects that are far vs close?
the muscles controlling the lens
constricted lens –> close objects
elongated long lens –> far objects
This is called accomodation
Name for the fluid inside of the eye
vitreous humor
Retina anatomy
layers + purpose + label diagram
Back
1. Photoreceptors: translate physical stim. to neural impulse
2. Bipolar cells: send info to next layer
3. Ganglion cells: neurons sending info to the brain
Front
Part of the retina which provides nutrients
Retinal Pigment Epithelium (RPE)
Photoreceptors
types + purpose + location
Rods:
- night vision
- black and white
- concentrated in periphery
Cones
- day vision
- colour sensing
- concentrated in the fovea
we have more rods than cones
Blind spot of the eye
name + why it exists/what it’s made of
Optic disc: composed of ganglion cell axons
Cells which combine information in the retina
names + location
Horizontal cells: between layers 1&2
Amacrine cells: between layers 2&3
Fovea
description
small depression in the retina where visual acuity is highest
Visual processing diagram
draw diagram + pathway labels
- optic chiasm
- optic tracts
- lateral geniculate nucleus (part of thalamus)
- primary visual cortex (occipital lobe)
Alternate names for the primary visual cortex
- Area V1
- Striate cortex
Area of the occipital lobe outside the primary visual cortex
name + what it contains + purpose
extrastriate cortex
contains: areas V2 through V5
purpose: processing colour, motion and object recognition
Streams of visual processing after the occipital lobe
names + purpose + location
Dorsal stream: where pathway - depth and motion
- ‘up’ to parietal lobe
Ventral stream: what pathway - colour and form
- ‘down’ to temporal lobe
what happens to visual information as it is processed?
it becomes compressed
(input from many cells condenses to few cells)
Evolution of the eye
basic stages, name + features
- light sensitive patch: detect *presence *of light
- curved “cup” eye: direction of light
- pinhole eye: help focus light
- crude lens: increase focusing
- adjustable lens: allows for accomodation to change focus with distance
Cumulative selection
elvolutionary process where adaptations are layered upon old adaptations
eg: the evolution of the eye –> gradual progression to a highly complex organ
2 broad categories of eyes
name + which creatures have them + basic features
Simple eyes
- found in vertebrates and mollusks
- eyeball, lens and retina
Compound eyes
- anthropods (insects and crabs)
- ommatidia, lens retina
Main two functions of the eye
- Resolution (acuity)
- Sensitivity (ability to get sufficient light)
What are the two features of vision that eye size can benefit?
Acuity or Night Vision
Eyes will typically evolve to either have more cones OR more rods
What are the two features of vision that eye placement can benefit
Depth perception or Field of view
Eyes on the front of the head have better depth perception and eyes on the sides of the head have a wider field of view
Eye development in humans
Prenatal events
2nd prenatal month
- eyes form
6th prenatal month
- eyes react to light
- random firing of retinal cells
Eye development in humans
Events after child is born
Newborn
- weak lense muscles
- inconsistent pupil reactions
- low cell density in retina
- retina cells are immature
3 months old
- almost adult-like focusing
11 years old
- complete visual brain area development
Myopia vs Hyperopia
