Visual System

Question 1

How do we see?

Answer 1

2-D–> 3-D

Question 2

Major Structures of eye

Answer 2

• pupil: regulates the flow of light to the retina
• retina: converts light into electric signal then sends it to the optic nerve and then to the brain
  iris: opens or closes the pupil to let in more or less light
• lens: focuses the rays of light for the back of the eye(retina)
  -fovea: focuses on sharp central vision optic nerve: carries visual messages

Question 3

The Pupil and the Lens

Answer 3

• Light enters the eye through the pupil, a hole in the iris.
• Ciliary muscles adjust the lenses to focus visual images sharply on each retina, regardless of the distance of the image from the eyes; this focusing is
  called accommodation.

Question 4

Wavelength

Answer 4

perception of color

Question 5

Intensity

Answer 5

perception of brightness

Question 6

Humans see light between () and () nanometers

Answer 6

380- 760

Question 7

Sensitivity VS Acuity

Answer 7

sensitivity: ability to see in dim light
Acuity: ability to see details

Question 8

Ciliaty Muscles

Answer 8

alters shape of lens

Question 9

Saccade

Answer 9

rapid eye movement

Question 10

Fovea

Answer 10

• (has neurons) allows acuity
• high acuity area at the center of the retina
• where ONLY cones are found

Question 11

Retina’s 5 layers (RHBAR)

Answer 11

receptor layer, horizontal cell layer, bipolar layer,
amacrine cell layer, and retinal ganglion cell layer.

Question 12

receptor layer

Answer 12

The receptor layer is the farthest from light; therefore, incoming light is distorted by
four layers of neurons before reaching the receptors

Question 13

Inverted vision

Answer 13

think of goggles in class

Question 14

Blind Spot

Answer 14

no receptors where information
exits the eye

Question 15

look @ mammalian retina

Question 16

Cones Vs Rods

Answer 16

Cones: photopic (daytime vision)
Rods: scotopic (night vision)// increase in sensitivity and decrease in acuity

** look at the convergence of of cones and rods pic

Question 17

Spectral Sensitivity Scale

Answer 17

shows relationship between brightness and wavelength

Question 18

Fixations

Answer 18

pauses

Question 19

Most visual system neurons respond to
change, not to steady input.

Question 20

Temporal Integration

Answer 20

combining info overtime to improve detection

Question 21

Visual Transduction

Answer 21

conversion of light to
neural signals by visual receptors

Question 22

Transduction

Answer 22

conversion of one form of energy to another

Question 23

Absorption spectrum

Answer 23

describes spectral sensitivity

Question 24

Rhodopsin is the pigment found in rods

Question 25

Bleaching reaction hyperpolarizes the rods

Question 26

Sodium channels in the dark Vs in light

Answer 26

dark: sodium channels stay partially open (release glutamate)
light: sodium channels close (don’t release glutamate)

Question 27

retina-geniculate-striate pathway

Answer 27

look at eye sight pathway

Question 28

Retinotopic organization

Answer 28

neurons with receptive fields close together in visual space have cell bodies close together in the cortex

Question 29

Contrast enhancement

Answer 29

improve the perceptibility of objects in the scene by enhancing the brightness difference between objects and their backgrounds.

Question 30

Lateral inhibitions

Answer 30

neuron’s response to a stimulus is inhibited by the excitation of a neighboring neuron.

Question 31

Dorsal Vs Ventral Stream

Answer 31

Dorsal: spacial perception (where)// behavioral control path
Ventral: pattern recognition (what)// conscious path

Question 32

Retinex Theory

Answer 32

color is determined by the proportion of light of different wavelengths that a surface reflects

Question 33

Component Theory (Trichromatic theory)

Answer 33

-Two cells types color, one brightness
- Accounts for color afterimages (colors that don’t mix)