Chapter FIve Flashcards
Vision
1
Q
VIsion
A
- Physical stimulus: light particles and waves; electromagnetic radiation
- Eyes transduce electromagnetic radiation (light)
- Small range that can be detected
- Birds and insects can see shorter wavelengths of light
- Snakes can detect infrared
- Wavelengths of light bounce off of objects and the reflective light hits our eye
2
Q
Cornea
A
- clear outside of the eye that light oases through;
- bends and focuses light
3
Q
Pupil
A
- black spot in the center of the eye;
- the hole at the center of the iris
4
Q
Iris
A
- aperture that expands or opens of the pupil depending on the eye;
- colored part
5
Q
Lens
A
- hidden behind the pupil;
- functions the way a camera lens functions;
- allows us to focus on things (fingers) changes shape;
- soft and flexible;
- muscles attached to it pull or relax
6
Q
Retina
A
- Where transduction occurs
- 3 layers
7
Q
Retina Layers
A
- Top layer: Ganglion cells; take information to the brain; combine the activity of cones and rods; receptive field for ganglion cells that corresponds with an area of the visual field
- Middle layer
- Bottom layer: Receptor cells
- The light has to pass through other layers to get to the photoreceptors
- Not all the light is making it to the photoreceptors
8
Q
Photopigments
A
- Light sensitive
- Light hits them and causes chemical reactions and that changes the amount of neuro transmitter being releases
- Cones
- Uses more light
- Distinguish color
- Depending on the photopigment different wavelengths of light are going to activate different photoreceptors
- Rods
- Don’t require as much light
- Cant discriminate between different colors
- Photoreceptors are not evenly dispersed throughout the retina
- Blind spot = where the axons leave the eye and have no photoreceptors
9
Q
Fovea
A
- Cones are almost exclusively located in the fovea
- Densely packed in the fovea than in other parts of the eye
- This is where the light from objects we are directly looking at are projected
- Rods are on the other part and get light from the background and not as densely packed
10
Q
How to we detect color
A
- Activate pigments in blue, red, and green cones
- Trichromats
- Primary colors make up the other colors
- detect other colors by seeing how much they activate the three cones
- i.e. yellow activates blue and green
- Red green color blindness
- Mantis shrimp
- 12 different types of cones
- The most we know of different animals
- Cant tell the difference between colors we know
- Underwater filters out long wavelengths and see mostly blue
- Polarized light
11
Q
On-center Off-surround cells
A
- Center of the receptive field
- If the light is in the center of the receptive field the ganglion fires
- Surround of the receptive field
- If the light doesn’t cross the center of the receptive field, the ganglion cell is inhibited
- If light falls partially on the center and partially on the surround it leads to no change
- on-center off-surround ganglion cells and LGN cells
- Lateral inhibition
- Helps us detect the edge of things
- Where an object ends and where it begins
- Allows the brain to get very specific information about where the edge is, where light meets dark
12
Q
VIsion and the thalamus
A
- Lateral geniculate nucleus
- On-center off-surround cells
- From the LGN the information goes to the primary visual cortex in the occipital lobe
- Consequence is both hemispheres receive information from both eyes
- Cells are organized based on which eye the information is coming from
13
Q
ocular dominance columns
A
- Its organized so that one area is only responding to information from the left eye
- Keeps the different eyes distinct because both hemispheres receive input from all of them
- Having two overlapping means that each eye gets a different view of an object
- Helps with depth perception
14
Q
What happens when you limit the input of one eye to the visual cortex?
A
- The eye that gets covered up gets very little amounts of cortex that continue to process information from it
- More of the cortex is attributed to the good eye
- If the eye is uncovered, the monkey wont see very well out of the eye because not as much of the brain is processing information from it
- When young children have a good eye and a weak eye doctors cover the good eye so that the weak eye can catch up
- Auditory processing in blind people; occipital lobe lights up
15
Q
SImple cells in V1
A
- The firing processing of these neurons are different than the ganglion cells and LGN
- Putting the light in the receptive field and of the correct orientation cause them to fire
- This cell likes vertical rather than horizontal
- Horizontal will not cause it to fire
- These cells are responding to more complicated stimuli in more complicated ways
