Vision

Question 1

Three steps from stimulus to perception

Answer 1

Reception, transduction, coding

Question 2

Light

Answer 2

Adequate stimulus for vision. Described as a particle of energy wave of energy (e-magnetic energy)

Question 3

2 properties of light

Answer 3

1. Wavelength = color

2. Intensity= brightness

Question 4

Wavelengths of light (violet-Red) based on rainbow

Answer 4

400-700

Question 5

Pupil

Answer 5

Where Light enters the eye.

Size changed in response to changes in illumination

Question 6

Sensitivity

Answer 6

Ability to see when light is dim

Question 7

Acuity

Answer 7

Ability to see details

Question 8

Lens

Answer 8

Focuses light on the retina

Question 9

Ciliary muscles

Answer 9

Alter the shape of the lens as needed

Question 10

Accommodation

Answer 10

Process of adjusting the lens to bring the images into focus

Question 11

Blind spot

Answer 11

No receptors where info exits the eye

Question 12

Completion

Answer 12

Visual system uses info from cells around the blind spot to fill in blind spot (completion)

Question 13

Fovea

Answer 13

High acuity area at center of retina

Question 14

Thinning of ganglion cell layer…

Answer 14

Reduces distortion due to cells between The pupil and the retina

Question 15

Duplicity theory of vision

Answer 15

Cones and rods mediate different kinds of vision

Question 16

Cones

Answer 16

Photopic (daytime vision)

High acuity color info in good lighting

Only cones found in fovea

Question 17

Rods

Answer 17

Scotopic (nighttime vision)

High sensitivity, allowing low acuity vision in dim light. Lack detail and color info.

More convergence. Increasing sensitivity while decreasing acuity.

Question 18

Visual transduction (in light) step 1

Answer 18

Light bleached rhodopsin molecules

Question 19

Visual transduction (light) step 2

Answer 19

Sodium channels close

Question 20

Visual transduction (light) step 3

Answer 20

Sodium ions cannot enter rods = rods hyperpolarized

Question 21

Visual transduction (light) step 4

Answer 21

Glutamate release is reduced

Question 22

Trichromatic theory of color vision

Answer 22

3 different kinds of cones

1. Short wavelength: blue
2. medium wl: green
3. long wl: red and yellow

Discriminate among wavelengths by ratio of activity across 3 types

Intense light increases activity of all 3 but ratio of responses stays same

Question 23

Opponent process theory

Answer 23

2 different classes of cells in the visual system for encoding color and another one for encoding brightness

Hering: each of 3 cells encoded 2 complenatry color perceptions

1class= signaled red by changing activity in one direction (ex:depolarization and hyperpolarization)

2class= signal blue and yellow in same opponent fashion.

Question 24

Evidence to support opponent process

Answer 24

1. If state at something yellow for 1 minute and look at white = see blue. (Same for is u stare at red, green = green, red) afterimage
2. cells in lateral geniculate nucleus may be excited by green light and inhibited by red light.

Question 25

Blue yellow color deficiency

Answer 25

Very rare

Question 26

Red-green color deficiency

Answer 26

Most common ^ due to deficient cone that process that colors wavelength

Question 27

Protanopia

Answer 27

Red weak Brightness of red. Orange. And yellow is reduced. Shift to appearing green

Question 28

Deuteranopia

Answer 28

Green weak Same perceptual problem with red. Orange. Yellow. green brightness reduced. Shift to see red.

Question 29

Receptive fields

Answer 29

Portion of retina in which light affects the activity of a given neuron Light in retinal area leads to excitization or inhibition of cortical cell

Question 30

Define receptive fields in 2 ways

Answer 30

An area of retina An area of visual field ^ equivalent

Question 31

Left visual field reaches...

Answer 31

Right primary visual cortex | Vice versa for Right visual field

Question 32

Similarities seen at all three neurons (retina,geniculate,striate)

Answer 32

Receptive fields in fovea smaller than periphery Neurons receptive fields are circular Neurons Monocular Many neurons with excitatory and inhibitory area.

Question 33

Retinoptopic organization

Answer 33

(Striate system) Info received at adjacent portions of retina remain adjacent in straite More cortex is devoted to areas of high acuity 25% of primary visual cortex is dedicated to input from fovea

Question 34

Magnocellular layers

Answer 34

Big cell bodies (bottom two layers of LGN) Responsive to movement Input from rods

Question 35

Parvocellular layers

Answer 35

Small cell bodies, top 4 layers of LGN Color, detail and still/slow objects Input from cones

Question 36

Visual cortex organization

Answer 36

Lateral geniculate area -> primary visual cortex (V1)-> secondary visual cortex (V2)-> association cortex

Question 37

Parallel processing

Answer 37

Info flow through components over multiple pathways Combined activity of many interconnected cortical and subcortical areas of each sensory system

Question 38

V1+V2

Answer 38

Feature detectors: neurons respond to presence of a particular feature Spatial frequencies

Question 39

Inferior temporal cortex

Answer 39

Large receptive fields Detailed info about stimulus shape

Question 40

Posterior parietal cortex

Answer 40

Spatial attention: where in space stimulus allocated Spatial neglect: ignore one power of body or extrapersonal space

Question 41

Visual agnosia

Answer 41

Inability to recognize objects

Question 42

Prosopagnosia

Answer 42

Inability to recognize faces. Able to read and write and reocgnize other objects. Trouble recognizing different kinds of animals and cars. Difficulty with complex visual discriminations Evidence from brain imaging studies in normals: objects and faces processed by central stream.

Question 43

Middle temporal cortex (MT) (V5)

Answer 43

Motion perception info is processed

Question 44

Medial superior temporal cortex (MST) (V4)

Answer 44

Motion perception info is processed

Question 45

Motion perception

Answer 45

Cells respond selectively to speed and direction of movement

Question 46

Disorders of motion perception monkeys...

Answer 46

Monkeys with damage to MT or MST respond inaccurately to moving visual stimuli

Question 47

MT damage in humans

Answer 47

Causes motion blindness