Chapter 7: vision

Question 1

retina

Answer 1

turns light into neural signals through transduction

Question 2

cornea

Answer 2

transparent outer layer; bends light rays through refraction and is primarily responsible for forming the image on the retina

Question 3

lens

Answer 3

changes shape to fine-tune the image on the retina

Question 4

accommodation

Answer 4

process where ciliary muscles adjust the lens to bring nearby objects into focus

Question 5

myopia

Answer 5

(nearsightedness) difficulty seeing distant objects; eye grows to long

Question 6

photoreceptors

Answer 6

sensory neurons that detect light (rods and cones)

Question 7

rods

Answer 7

most active at low light and respond to visible light of almost any wavelength

Question 8

cones

Answer 8

different varieties that respond differently to light of varying wavelengths: see color

Question 9

bipolar cells

Answer 9

interneuron in the retina that receives information from rods and cones and passes information to retinal ganglion cells

Question 10

ganglion cells

Answer 10

cells whose axons form the optic nerve (only ones that use action potentials)

Question 11

optic nerve

Answer 11

carries information to the brain

Question 12

horizontal cells

Answer 12

make contacts among the photoreceptors and bipolar cells

Question 13

amacrine cells

Answer 13

contact both the bipolar cells and the ganglion cells

Question 14

scotopic system

Answer 14

a system in the retina that operates at low light and involves rods but is insensitive to color; sides of the retina(periphery)

Question 15

convergence

Answer 15

phenomenon of neural connections in which many cells send signals to a single cell

Question 16

photopic system

Answer 16

high levels of light, shows sensitivity to color and involves the cones; found mostly in the fovea

Question 17

rhodopsin

Answer 17

the photopigment in rods that responds to light and cause signaling chain that leads to hyperpolarization(photons=quanta of light)

Question 18

pupil

Answer 18

deals with the large range of intensities by adjusting the size (and opening in the iris)

Question 19

range fractionation

Answer 19

each sensory receptor cell specializes in just one part of the overall range of intensities

Question 20

photoreceptor adaptation

Answer 20

each photoreceptor constantly adjusts its sensitivity to match the average level of ambient light

Question 21

fovea

Answer 21

the center region of the retina has a high density of smaller, tightly-packed cones with high acuity

Question 22

visual acuity

Answer 22

a measure of how much detail we see and is
sharpest in the center of the visual field.

Question 23

optic disc

Answer 23

where blood vessels and ganglion cell axons leave the eye

Question 24

blind spot

Answer 24

region on the retina that is sightless due to lack of photoreceptors in the optic disc

Question 25

optic cortex

Answer 25

receives action potentials from ganglion cells

Question 26

visual field

Answer 26

the area that is visible without movement of the eye or head

Question 27

topographic projection

Answer 27

This organization is preserved as the information travels through the
brain

Question 28

on-center bipolar cells

Answer 28

turning on light in the center of its receptive field excites the cells because it receives less glutamate, which inhibits this type of bipolar cell

Question 29

off-center bipolar cells

Answer 29

turning off light in the center of the field excites the cells because they receive more glutamate and are depolarized

Question 30

on-center ganglion cells

Answer 30

on-center bipolar cells excite when light is turned on

Question 31

off-center ganglion cells

Answer 31

Off-center bipolar cells excite when light is turned off

Question 32

lateral inhibition

Answer 32

sensory receptor cells inhibit information from neighboring receptor cells, producing a contrast effect at the edges of regions

Question 33

simple cortical cells

Answer 33

(bar detectors/ edge detectors) respond to an edge or bar of a particular width, orientation, and location in the visual field

Question 34

complex cortical cells

Answer 34

respond best to a bar of a particular width
and orientation that is in motion anywhere in the visual field.

Question 35

spatial frequency model

Answer 35

the visual system analyzes the number of light-dark (or color) cycles in any stimulus

Question 36

wavelength

Answer 36

color is perceived by the visual system as we detect differences in the photons within a certain range.

Question 37

trichromatic hypothesis

Answer 37

Three different types of cones
* Each responds to a specific, different part of the spectrum
* Each has a separate pathway to the brain
* Color recognized based on which receptors are activated

Question 38

opponent-process hypothesis

Answer 38

Four unique hues
* Three opposed pairs of colors
* Three physiological processes with opposed positive and
negative value are the basis of color vision

Question 39

spectrally opponent cells

Answer 39

(color-opponent): have opposite firing responses to different regions of the spectrum

Question 39

ventral stream

Answer 39

identifying objects (what)
o Damage causes problems in perceiving faces and
objects.

Question 40

dorsal stream

Answer 40

assessing the location of objects (where),
and guiding our movement toward them

Question 41

amblyopia

Answer 41

misalignment of the eyes; reduced visual acuity not caused by optical or retinal damage
* visual cortex suppresses information from one eye
*eye muscles can be surgically adjusted to achieve better alignment; and use weak eye regularly