Ch.7 Study Guide

Question 1

Optic disc is the region of the retina that is devoid of photoreceptors because ganglion ______ axons & blood vessels exit the eyeball there

Answer 1

cell

Question 2

Pupil is the opening, formed by the iris, that allows light to ________ the eye

Answer 2

enter

Question 3

Ganglion cell is any class of cells in the retina whose axons form the _______ nerve

Answer 3

optic

Question 4

Rhodopsin is the photopigment in rods that responds to _________

Answer 4

light

Question 5

Myopia- nearsightedness; the inability to focus the retinal image of objects that are _____ away

Answer 5

far

Question 6

Amblyopia- reduced visual acuity of one eye that is not caused by optical or retinal _________________

Answer 6

impairments

Question 7

Transduction is the conversion of one form of energy to another, such as from light to neuronal _____________

Answer 7

activity

Question 8

Refraction is the bending of light rays by a change in the density of a medium, such as the cornea and the ____ of the eyes

Answer 8

lens

Question 9

Accommodation is the process by which the ciliary muscles adjust the lens to bring nearby objects into _______

Answer 9

focus

Question 10

Visual acuity is sharpness of _______

Answer 10

vision

Question 11

Fovea- the central portion of the retina which is packed with the highest density of photoreceptors and is the center of our ______

Answer 11

gaze

Question 12

Simple cortical cell- also called bar detector or edge detector. A cell in the visual cortex that responds best to an edge or a bar that has a particular width, as well as a particular orientation and location in the visual _______

Answer 12

field

Question 13

Complex cortical cell- a cell in the visual cortex that responds best to a bar of a particular size and orientation anywhere within a particular area of the visual field and that needs movement to make it respond __________

Answer 13

actively

Question 14

Topographic projection- a mapping that preserves the point-to-point correspondence between neighboring parts of ________. For example, a topographic projection extends from the retina to the cortex

Answer 14

space

Question 15

Blindsight- the paradoxical phenomenon whereby, within a scotoma, a person cannot consciously perceive visual cues, but may still be able to make some _________ discrimination

Answer 15

visual

Question 16

Lateral inhibition- the phenomenon by which interconnected neurons inhibit their neighbors, producing contrast at the edges of _________

Answer 16

regions

Question 17

ciliary muscles- one of the muscles that control the shape of the lens inside the eye, focusing an image on the ________

Answer 17

retina

Question 18

Rods is a type of photoreceptor in the retina that responds to visible ______ almost any wavelength (responsible for vision in low light conditions)

Answer 18

light

Question 19

Cones are photoreceptors in the retina that come in ________ different varieties, which respond differently to light of varying wavelengths (responsible for color vision & sharp, detailed vision in bright light)

Answer 19

several

Question 20

The cells of the eye are activated in this order: photoreceptors (rods and cones) detect light, then transmit signals to bipolar ______, which in turn transmit signals to ganglion cells, whose ________ form the optic nerve and carry the _________ information to the brain

Answer 20

cells; axons; visual

Question 21

Photopic (visual system)- a system in the retina that operates at high levels of light, shows sensitivity to _______, and involves the cones.

Answer 21

color

Question 22

Scotopic (visual system)- a system in the retina that operates at low levels of light and involves the _____.

Answer 22

rods

Question 23

optic ataxia- spatial disorientation in which the patient is unable to accurately reach for objects using visual ____________

Answer 23

guidance

Question 24

trichromatic hypothesis of color processing- stating that there are ___ different types of cones, each excited by a different region of the spectrum and each having a separate pathway to the brain

Answer 24

3

Question 25

Dorsal processing stream is responsible for appreciating the spatial location of objects and for visually guiding our ______________ toward them

Answer 25

movement

Question 26

Ventral processing stream is responsible for visually identifying __________

Answer 26

objects

Question 27

on-center bipolar cells- located in the inner nuclear layer of the retina and act as a relay between photoreceptors (rods and cones) and ganglion cells

Question 28

On- center bipolar cells will ______________ (become more positive by light stimulation in the receptive field center) in response to light (& hyperpolarize in the dark)

Answer 28

depolarize

Question 29

When light is turned on, on-center bipolar cells __________(excite) in-center ganglion cells

Answer 29

depolarize

Question 30

When light is turned off, off-center bipolar cells depolarize (excite) ____-center ganglion cells

Answer 30

off

Question 31

On-center/off-surround: referring to a concentric receptive field in which stimulation of the center excites the cell of interest while stimulation of the surround inhibits it.

Question 32

receptive field of a sensory cell consists of the stimulus features that excite or inhibit the _____

Answer 32

cell

Question 33

lateral geniculate nucleus(lgn)- the part of the ___________ that receives info from the optic tract & sends it to visual areas in the occipital _________

Answer 33

thalamus; cortex