Vision Flashcards
(21 cards)
1
Q
Blindsight
A
Damage to V1 leads to blindness
2
Q
Light
A
Wavelength of light determines colour
3
Q
The eye
A
- Light enters through cornea, pupil, lens
- Lens focuses light and inverts image
- Light focused onto retina
4
Q
Retina
A
Rods, cones, ganglion cells, horizontal cells, bipolar cells, amacrine cells
5
Q
Rods
A
- Abundant in retina
- Respond to faint light
- Being hit by light reduces firing rate
6
Q
Cones
A
- Abundant in and near fovea
- Less active in dim light, more useful in bright light
- Essential for colour vision
- Being hit by light reduces firing rate
7
Q
Ganglion cells
A
Axons join together and travel back to the brain
8
Q
Bipolar cells
A
- Send messages to ganglion cells
- Receive messages from receptors at back of the eye
- Colour processing
9
Q
Amacrine cells
A
- Get information from bipolar cells
- Send information to bipolar and ganglion cells
- Refine input to ganglion cells
- Respond to shapes, directions of movement, changes in lighting and colour
10
Q
Horizontal cells
A
Send messages to amacrine and ganglion cells
11
Q
Fovea
A
Detailed, high acuity, lots of cells
12
Q
Visual pathway I
A
- Excites rods and cones
- Sends signals to bipolar and horizontal cells
- Signals collected in ganglion cells
13
Q
Visual pathway II
A
- Lateral geniculate nucleus - messages sent on to cortex
14
Q
Receptive fields
A
- Rods - very small region of space
- Cones - small space region, one colour
- V1 cells - areas of space, orientation of lines
- V2 and V3 cells - movement
- V4 cells - colour
15
Q
Fusiform gyrus
A
- Face recognition
- Damage causes prosopagnosia (inability to recognize faces)
16
Q
Ventral stream
A
What the object is
17
Q
Dorsal stream
A
Where the object is
18
Q
Theories of colour vision
A
Trichromatic, opponent-process, retinex
19
Q
Trichromatic theory
A
- Compare activation of 3 cone types
- Does not explain colour afterimages well
20
Q
Opponent-processing theory
A
- Colour detected along 3 axes: blue/yellow, red/green, white/black
- Bipolar cells react to changes in rate of firing cells
21
Q
Retinex theory
A
- Colour is too complex for the retina, must be in the cortex
