Vision

Question 1

________ connect the lens to the ciliary muscle

Answer 1

zonule fibers

Question 2

The cornea provides ______ of the
refractive (or focusing) power for the eye,
while the lens provides only ______.

Answer 2

~2/3,

~1/3.

Question 3

_________ capture photons of light and convert (transduction) them to an electrical signal (change in membrane potential), which is passed synaptically to , _______ & ________ and then to the
output cells of the retina, the ganglion cells

Answer 3

Photoreceptors (rods and cones),

bipolar cells and horizontal cells

Question 4

Cones mediate _____ vision, are concentrated in the fovea, and work well only in ______ light. Rods are
color insensitive and work best in dim light

Answer 4

color,

bright

Question 5

______ are the dominant photoreceptor away from the

fovea

Answer 5

rods

Question 6

Humans have about ______rods and ______ cones in each retina

Answer 6

100 million,

8 million

Question 7

in the dark photoreceptors have a relatively high

concentration of ______ which binds to and holds opens nonselective cation channels

Answer 7

cyclic GMP (cGMP),

Question 8

Ganglion cells have donutshaped
receptive fields and come in two opposite types
Some are excited by light shining
in their centers and inhibited by light in the periphery called _________. Others are the
opposite called ________.

Answer 8

(‘on’ center ganglion cells)

‘off ‘ center ganglion cells

Question 9

Bipolar cells can be either excited as in _____ or inhibited as in _____ by glutamate (due to different receptor types)

Answer 9

(OFF-center),

ON-center

Question 10

Bipolar cells always make ________ synapses on ganglion cells

Answer 10

excitatory

Question 11

Horizontal cells have excitatory receptors for _______released from photoreceptors, and make
_______ synapses on the neighboring photoreceptors in the field center

Answer 11

glutamate,

inhibitory

Question 12

the LGN represents the _______

visual field

Answer 12

contralateral

Question 13

Beyond the LGN, axons involved in
visual processing fan out in the ______ to the
visual cortex at the back of the brain

Answer 13

optic radiations

Question 14

the lower half of each retina (which
‘sees’ the upper half of the visual world) projects to the
______of each visual cortex (the lower bank of the
calcarine sulcus)

Answer 14

lower half

Question 15

Layers 1, 4, and 6 of LGN receive inputs from the ________ eye (these inputs desiccate at the chiasm)

Answer 15

contralateral

Question 16

layers 2, 3, and 5 of the LGN receive inputs from the ________ eye. (these inputs desiccate at the chiasm)

Answer 16

ipsilateral

Question 17

There is also a secondary segregation of information in the 6 layerspf LGN: Layers 1 and 2
receive inputs from the so-called ________while layers 3-6 receive inputs from the so-called _______.

Answer 17

magnocellular ganglion cells,

parvocellular ganglion cells.

Question 18

what does the Parvocellular System detect?

Answer 18

Object Vision – color, form, detail

Question 19

what are the 4 response properties of the Parvocellular System?

Answer 19

1. High acuity (fine detail)
2. Small receptive fields
3. Not responsive to motion
4. Color vision (input from cones)

Question 20

what are the 4 response properties of the Magnocellular System?

Answer 20

1. Low acuity (crude form)
2. Large receptive fields
3. Responsive to motion
4. No color vision (input from rods)

Question 21

thee foveal region, which occupies a tiny

fraction of the retina, occupies nearly ______ of the visual cortex

Answer 21

one-half

Question 22

each hypercolumn is divided in two parts, one half for each eye; these are called ______

Answer 22

ocular dominance columns

Question 23

describe hierarchical processing

Answer 23

Several cells with similar but spatially offset receptive fields converge on a higher order cell to create an altogether new type of receptive field.

Question 24

what is the receptor field shape of a simple cell?

Answer 24

Bar

Question 25

what is the receptor field shape of a complex cell?

Answer 25

edge

Question 26

It is from the _______ of the 3 cone
types by single wavelengths of light that the nervous system extracts the information it needs to
create cells in the cortex that respond only to particular colors

Answer 26

relative activities

Question 27

what is parallel processing in the visual system

Answer 27

dissimilar dimensions (e.g. color and form) must be analyzed by separate, but parallel, neural
systems.

Question 28

The Dorsal Pathway travels from V1 dorsally to the parietal lobe and is generally believed to be responsible for _______ vision

Answer 28

spatial

Question 29

Ventral Pathway travels ventrally from V1 to the temporal lobe and is generally believed to
be responsible for __________

Answer 29

object vision, including color, form, and pattern vision