Neurophysiology 2

Question 1

What describes the contrast

sensitivity function in strabismic amblyopes?

Answer 1

Localized deficit at the location of their suppression scotoma

Question 2

What describes the CSF in anisometropic amblyopes?

Answer 2

Overall optical defocus

Question 3

This is the ability to detect positional inaccuracies and

spatial localization

Answer 3

Hyperacuity

Question 4

Name 1 thing that is not a monocular sensory deficit in amblyopic eye.

Answer 4

Stereopsis

Question 5

T/F: The visual system remains more plastic for longer periods of time at higher levels of procesing.

Answer 5

True

Question 6

What’s the most plastic: retina, LGN or Visual cortex?

Answer 6

Visual cortex

Question 7

This is the initial formation of neuronal circuits that is not dependent on visual experience.

Answer 7

Pre-critical period

Question 8

This is a distinct onset of robust plasticity in response to visual experience when the initially formed circuit can be modified by experience.

Answer 8

Critical period

Question 9

This is after the end of the critical period, the same visual experience no longer elicits the same degree of plasticity.

Answer 9

Closure of critical period

Question 10

When does a humans CP start, heighten and plateau?

Answer 10

Start: at birth
Heightens: 1-3 yo
Plateau: 7yo

Question 11

What is the result from brief monocular deprivation of cats?

Answer 11

• only took 8 days

- ocular dominance columns were driven by non-deprived eye

Question 12

How do we determine/measure the critical period in humans?

Answer 12

Inter Ocular Transfer test

Question 13

The IOT test found that the CP for binocularity initiates between __ and __ of age.

Answer 13

6 mo and 1 year of age

Question 14

Astigmatism and anisometropia leads to amblyopia if they persist for how long?

Answer 14

2 years

Question 15

Cataracts and stimulus deprivation have a much more ____ effect than aniso.

Answer 15

severe

Question 16

This is the development of the synaptic connections between the neurons and the retention of these connections.

Answer 16

Binocular competition

- inputs from both eyes will compete for synapses onto the cortial binocular cell

Question 17

How do we strengthen the synaptic connection from the blured eye in order to balance the competition?

Answer 17

Occlusion therapy! (patch!)

Question 18

What is the main concern of full-time reverse occlusion?

Answer 18

May cause Bilateral amblyopia

Question 19

What amount of hours is needed for part-time reverse occlusion to be useful (in kittens)?

Answer 19

5 hours

- more equalization vs. 3.5 hrs

Question 20

Full time reverse occlusion in monocular deprived cats led to what finding?

Answer 20

Occlusion amblyopia, reduced acuity in the previously open eye

Question 21

What was the conclusion from the study of dark rearing cats?

Answer 21

• The critical period is delayed

- CP only begins when the animals are first exposed to light (need visual experience)

Question 22

Why was there a visual change in the dark-reared adult rat showing that monocular deprivation was effective?

Answer 22

• adult dark-reared rats have decreased levels of GABA receptors (increased plasticity of cortex)

Question 23

What is the important receptor when we’re talking about ocular dominance?

Answer 23

NMDA receptor

Question 24

What was the conclusion of PEDIG ATS 2A?

Answer 24

For moderate amblyopes (better than 20/80), 2 hours of patching with 1 hour of near work produces an improvement in VA similar to 6 hrs of patching.

Question 25

What was the conclusion of PEDIG ATS 2B?

Answer 25

For severe amblyopes (20/100-20/400), 6 hours of patching and 1 hour of near work was comparable to full-time patching

Question 26

What is the MOA of pharmaceutical agens acting to tx amblyopia?

Answer 26

Reduces gabanergic inhibition to restore plasticity in the visual system

Question 27

The drug, Levodopa/Carbidopa, showed what 3 results when studied in patients with amblyopia?

Answer 27

• 2 lines improvement in VA
• greater improvement in patients younger than 8 yo
• No reversal of improved VA at 6 mo followup

Question 28

The critical period in animal models can be _____ depending on visual experience.

Answer 28

delayed

Question 29

The hebbian model suggests that the _____ is the neuronal location where plasticity changes occur

Answer 29

synapse

Question 30

The NMDA receptor is made up of 2 subunits, the NR2b, which is more common at ______; and the NR2a which binds during_____.

Answer 30

Nr2B = birth
Nr2A = during adulthood

Question 31

Dark rearing has shown ______ the onset of critical period in adult rats and cats, proving that _____ is necessary to trigger the events of ocular dominance.

Answer 31

delay, visual experience

Question 32

PEDIG now recommends _____ with 1 hour near work for moderate amblyopes and ______ w/ 1 hr near work for severe amblyopes.

Answer 32

2 hrs, 6 hrs

Question 33

Adult plasticity studies showed that the critical period is never fully _____.

Answer 33

closed

Question 34

Levodopa/Carbidopa increase ____ levels in the CNS.

Answer 34

dopamine

Question 35

Reduced GABAergic ___ facilitates synaptic plasticity.

Answer 35

inhibition

Question 36

_____ enhances histone acerylation levels, which promotes plasticity in adult rat’s visual cortex

Answer 36

Valproic Acid

Question 37

Fluoxetine infusion studies have shown a novel ______ creation in V1 of adult amblyopic rats, with a corresponding rescue of the previously MD eye.

Answer 37

synapse

Question 38

Drugs that ___ inhibition should promote plasticity, and this has led to pharmacological intervention as a potential avenue for amblyopia tx.

Answer 38

reduce gabanergic inhibition