Central Visual Processing II Lec13

Question 1

Synaptic plasticity is the ability of a
synapse between two neurons to
change in ___ or ___

Answer 1

strength or effectiveness.

Question 2

. Input from the LGN into V1 maintain ___ segregation and setup the OD columns in V1

Answer 2

monocular

Question 3

Visual deprivation and
competition study

1 is a cell
that is completely dominated by ____ eye
input

Answer 3

contralateral

Question 4

Visual deprivation and
competition study

, 7 is dominated by the ___ eye

Answer 4

ipsilateral

Question 5

Visual deprivation and
competition study

__
is a binocular cell equally driven by either eye.

Answer 5

4

Question 6

Visual deprivation and

competition

In the normal adult primate, how many 1,7,4s are there?

Answer 6

equal numbers of cells driven by each eye (i.e. the
numbers of cells with OD=1,2,3 about equal cells
with OD=5,6,7),

Question 7

Experiment: monocular deprivation (MD)
- One eyelid is sutured soon after birth and it
remains closed for 6 months

after opening eyelid

what was the distribution of the OD scale?

Answer 7

all were either 1s or 7s meaning

t nearly all cells are driven by the eye that wasn’t
sutured close

Question 8

Experiment: monocular deprivation (MD)
- One eyelid is sutured soon after birth and it
remains closed for 6 months and then open

all cells designated 1s and 7s

was this change permanent?

Answer 8

yes

Question 9

Experiment: monocular deprivation (MD)
- One eyelid is sutured soon after birth and it
remains closed for 6 months and then open

all cells designated 1s and 7s

where in the brain were there changes?

Answer 9

in V1 itself, not in the retina, because
the eye, retina, LGN, optic radiations, etc were found
all to be normal.

Question 10

what condition resutls from monocular deprivation

(all cells driven by eye that wasn’t sutured closed?)

Answer 10

amblyopia.

Question 11

Intravitreal injection in one eye, of 3H-proline in a v1 monocular deprived and a v1 normal monkey

what changes were noticed in the cortex?

Answer 11

• Under monocular deprivation, the “good” eye (non-deprived) has taken over the territory normally
  occupied by the other (occluded, deprived) eye

Question 12

Normal OD columns exhibit a roughly equal ___ of
bands for each of the two eyes

Answer 12

width

Question 13

Normal OD columns exhibit a roughly equal width of
bands for each of the two eyes, whereas in monocular deprivation, the deprived eye bands are much
___

Answer 13

thinner

Question 14

critical period in humans

Answer 14

birth and 6-8 years

s (in a kitten, 6 months in a monkey, 6-8 years in a
human child).

Question 15

A few ___ of deprivation
can permanently altered the development of the OD
columns during the critical period

Answer 15

days

Question 16

The effects of a brief period of monocular deprivation
may be partially reversed if,

Answer 16

during critical period

1. sutured eye is opened
2. nonsutured eye is sutured

* allows it to regain its cortical territory

Question 17

• Binocular deprivation (BD) during the critical period
  seems to ___ the critical period somewhat

Answer 17

lengthen

Question 18

• The binocular deprivation experiments show that the
  effects of MD are not simply the result of “disuse”, but
  instead indicate an

Answer 18

active competition

Question 19

strabismus, as a
___ disorder

Answer 19

peripheral

Question 20

amblyopia, as a ___
disorder.

Answer 20

central

Question 21

Strabismus invovles the

Answer 21

extracocualr muscles

Question 22

strabismus is caused by a a misalignment of the two

eyes preventing

Answer 22

proper binocular vision

Question 23

what can strbismus lead to if occuring in the young

Answer 23

ambylopia

Question 24

Amblyopia: (lazy eye), a central disorder resulting from

Answer 24

an imbalance or lack of visual coordination between the
two eyes during development

Question 25

Amblyopia deficits include

Answer 25

poor vision or acuity in one eye compared to the stronger eye

Question 26

causes of Amblyopia: include

Answer 26

1. strabismus 2. refractive errors 3. cataracts

Question 27

Amblyopia is Characterized ## Footnote by an abnormal development of connections in the \_\_\_

Answer 27

visual cortex

Question 28

what eye does a patch go on in ambyopia? what can be a side effect?

Answer 28

on good eye can cause poor bionuclar depth (stereopsis)

Question 29

- Normal development requires both a match in strength of input from each eye AND a

Answer 29

coordination of inputs

Question 30

r alternation of two strong eyes, or amblyopia (one weak eye) USUALLY LEADS TO

Answer 30

poor stereopsis (depth vision)

Question 31

Proper binocular visual development requires

Answer 31

1. the proper convergence of the two eyes 2. matching * *refraction** and **image quality**

Question 32

injection of 3h proline in one eye in adult reveals

Answer 32

ocular domiannce in v1

Question 33

injection of 3h proline in one eye in the fetus reveals

Answer 33

no ocular dominance columns

Question 34

strabismus in an adult can lead to

Answer 34

diplopia

Question 35

Hebb’s hypothesis:

Answer 35

“Cells that fire together wire together”

Question 36

Experiments establishing, activity-based, Hebbian competition include:

Answer 36

1. diff. between bincoular deprivation and monocular deprivation 2. TTX silence retinal output supress MD 3. GABA application silencing cortical cells supress MD 4. Artificial electrical stimulation of the optic nerves after TTX injection in the eyes, synchronous or asynchronous

Question 37

what two experiments supressed moncular depirivation

Answer 37

injections fo TTX silencing retinal ouput (ganglion cells) GABA in cotex blocking cortical cells

Question 38

electrostim is applied synchronously to the two optic nerves, ___ OD columns form.

Answer 38

no segregated OD columns form.

Question 39

electrostim is applied **_asynchronously_** to the two optic nerves, ___ OD columns form.

Answer 39

OD columns form

Question 40

\_\_\_ of NMDA receptors reduce ocular dominance plasticity and the refinement of receptive-field properties

Answer 40

Antagonists

Question 41

The overall concentration of NMDA receptors in the visual cortex peaks with the

Answer 41

critical period for ocular dominance plasticity

Question 42

The NMDA contribution to the visual response drops in layers ___ as ocular dominance columns segregate.

Answer 42

4-6

Question 43

Examples of adult cortical plasticity: (4)

Answer 43

1. recovery from brain injury 2. Rapid fill-in of the cortical representation after a retinal lesion, then axonal growth 3. - Analogous cortical reorganization of somatotopic maps under conditions of digit re-afferentation 4. phantum limb

Question 44

By depriving the sensory cortex of input what happened intially?

Answer 44

was silent in the region deprived of input.

Question 45

By depriving the sensory cortex of input what happened over time?

Answer 45

that cortical region became active again, resulting in a shift in the topographic maps

Question 46

. The input deprived cortex had “stolen” input from __ cortex, using the same mechanisms of competition and plasticity seen in the developing brain.

Answer 46

adjacent

Question 47

activity in only one axon synapse may be insuffiecent to drive the post synaptic cell to threshold so it triggers ___ strengthening mechanism

Answer 47

hebbian