Neuroplasticity

Question 1

Neuroplasticity

Answer 1

Ability of the brain to exhibit changes in neurons and synaptic connections as a result of
environmental interactions.

Question 2

Which sensory system is the most plastic

Answer 2

Visual system

Question 3

Visual adaptation

Answer 3

short-term change in sensitivity or perception caused by
the aftereffects of exposure to a visual pattern.

Question 4

Visual perceptual learning

Answer 4

A long-term improvement in performance on a visual task.

Question 5

What is a deviant stimuli

Answer 5

A deviation from the frequently occurring standard stimulus. deviant stimuli cause large spike in activity

Question 6

Where in visual cortex does deviant stimuli spikes occur

Answer 6

In layer 2/3

Question 7

Impact of exercise on perceptual learning (Virethrone et al., 2021)

Answer 7

our findings suggest that exercise alone can influence visual processing, but we did not find evidence that combining exercise with patching enhances visual plasticity beyond patching alone.

Question 8

Vernier acuity task

Answer 8

Tests visual perceptual learning. Measures the ability to discern a disalignment among two line segments.

Question 9

Visual perceptual learning-VPL

Answer 9

defined as performance enhancement on a visual task as a result of visual experience and has been regarded as a manifestation of brain plasticity.
Studies of VPL mechanisms should distinguish the process that leads to learning from the changes resulting from learning.
You are able to improve visual perceptual learning.
What’s interesting is even if you are not conscious of it, it is not necessary for you to be able to improve visual perceptual learning, this is demonstrated in rapid serial visual presentation tasks

Question 10

Homeostatic visual plasticity

Answer 10

Process of temporarily covering one eye can cause a shift in visual dominance toward the covered eye

Question 11

What happens when visual system is unbalanced

Answer 11

Visual hallucinations, occurs in neuropsychiatric disorders like schizophrenia- disorder is associated with visual processing impairments like contrast sensitivity and percetual orgnaisation.

Question 12

What is the clinical evidence for plasticity in the visual system

Answer 12

Amblyopia treatment
Stroke/ Injury recovery
Charles bonnet syndrome

Question 13

Charles bonnet syndrome- visual plasticity

Answer 13

causes visual hallucinations to those who have lost a lot of sight, e.g. in age-related macular degenration or cataracts. This phenomenon is similar to the way people feel phantom limbs. Confabulation of visual information causes these hallucinations. The hallucinations can be still or move. The hallucination can be both formed or unformed. Being in the dark can make hallucinations more likely

Question 14

Ganzfeld technique.

Answer 14

Perceptual deprivation artificially induces ganzfeld visual hallucination. Blindford yourself with white material tape a half over each eye, then listen to white noise with a red light over you (uniform light).

“Underactivity in the sensory cortices that triggers the brain to start filling in the gaps- confabualation of vision”

Question 15

Difference between Ganz Flicker and Ganzfeld

Answer 15

Ganzflicker was more effective than Ganzfeld at eliciting simple hallucinations, while complex hallucinations remained equivalent across the two conditions. Complex hallucination more likely from Ganzfeld.

Question 16

What is Amblyopia

Answer 16

Abnormal visual development
most common cause of visual impairment among children, affecting approximately 2 to 3 out of every 100 children.

Affects central vision- peripheral remains normal

Question 17

When can Amblyopia be fixed?

Answer 17

before the critical period is finished, before age 7.
age 7-17 do respond to treatment.

Question 18

The critical period can also be termed….

Answer 18

Ocular dominance plasticity.

Question 19

Treating amblyopia in Adults Versus children

Answer 19

Children: atropine to relax muslce for eye or patching over good eye for months.

Adults: visual lost if crticail period is over- need to identify ways to enhance plasticity

Question 20

Ocular dominance

Answer 20

Prefrence for one eye H&W 1968

Balance in OD is crucial for binocular vision.

Question 21

ODI and its range

Answer 21

Ocular dominance index.

ODI ranges from +1 to −1, positive value indicates contralateral bias
negative value an ipsilateral bias.

+1 indicates OD now lies closer to contralateral eye

Question 22

What mimics Amblyopia

Answer 22

Monocular deprivation

Question 23

What visual aspect is impacted in amblyopia?

Answer 23

Binocular vision and stereopsis also impacted parlty due to decreased visual acuity

Question 24

Visual acuity def

Answer 24

the clarity or sharpness of vision

Question 25

Stereopsis def

Answer 25

Visual fucntion. Stereopsis refers to the perception of depth that occurs due to the slight positional differences in the images received by each eye. This binocular disparity is used by the brain to estimate the depth of objects relative to the observer's point of focus.

Question 26

What do both Adult and juvenile plasticity depend upon

Answer 26

NMDA receptors

Question 27

Effect on V1 after monocular deprevation

Answer 27

If the contralateral eye was shut then the number of cells would deplete there and increase in the ipsilateral side of the V1. This process is driven by synaptic plasticity- Hebbian plasticity

Question 28

Critical Period def

Answer 28

Time window in early life that the organization of neural circuits is extremely susceptible to external environments because the brain is very plastic. Human: first year most important, but extends to 5-10 years

Question 29

Critcial period for stereopsis

Answer 29

extends through late infancy and early childhood and continues to at least 4.6 years of age.

Question 30

critical period in layers of v1

Answer 30

Cells at higher levels of the system have a critical period that lasts for a longer time. For example, the ocular dominance of cells in layers II, III, V, and VI of the primary visual cortex can be changed by monocular deprivation after the ocular dominance of cells in layer IV has been established

Question 31

What does MD do to cells in OD

Answer 31

Shifts it from OD eye to other eyesm so cells decrease in OD eye and spread more toward an equal or other eye spread

Question 32

What are the strucutral changes following MD and in which V1 layer does this happen?

Answer 32

In layer 4 and in dLGN Spines retract and density lower. Size of neurons lower They saw rapid OD plasticity - just one day of MD causes rapid shift in OD

Question 33

Experience-dependent structural plasticity at pre- and postsynaptic sites of layer 2/3 cells in developing visual cortex- Sun et al 2019 study

Answer 33

Fluorescent labelling spines with PSD95 or SYP-GFP (presynaptic marker) and GFP for layer 2/3 neurons 2p imaging to track over days Results: MD induces rapid changes in synaptic structure & spine numbers corresponding to population response. Ocular dominance in individual neurons tightly correlate with its spine remodeling Spines serve as an anatomical basis for rapid ocular dominance plasticity in L2/3 After reopening the deprived eye within the critical period, recovery of responses to normal levels occurs within 2 days

Question 34

DIfference in contralateral and ipsilateral eye following MD?

Question 35

Disadvantage of Sun et al 2019 study

Answer 35

cannot distinguish if synapse is listening to input from the contralateral or ipsilateral eye

Question 36

Sun, 2019 Post synaptic changes

Answer 36

Rapid remodeling of postsynaptic spines in response to MD: 1.Significant increase in spine elimination after 3 days of MD (15.6% vs 7.9% in controls) 2.Decrease in spine formation (5.4% vs 8.5% in controls) 3.Bimodal changes in spine density: some neurons lost many spines while others gained spines. This correlated with the neurons' ocular dominance preference

Question 37

**(look at papers for this) VEP for MD recordings of contra & ipsi eye

Answer 37

VEPs (measure electrical signal of visual cortex in response to stimuli) used to measure cortical plasticity

Question 38

Name the therapies to increase adult plasticity

Answer 38

1. Pharma-Serotonin signalling enhance plastic changes (fluoxetine- the depression drug) Activation of Rho GTPase- increases plasticity too 2.Transplantation of Paravlb and Sst interneruons. The age of transplanted interneuron defines the new critical period. Transplanted interneurons form numerous, weak synaptic connections 3. Running (disputed in recent studies) -Running Promotes Recovery From Amblyopia in Adult Rodent models

Question 39

Strabismus def

Answer 39

abnormal alignment of the eyes; the condition of having a squint.

Question 40

Amblyopia is most likely to occur as a result of

Answer 40

Monocular deprivation during childhood

Question 41

Do strcutral changes occur in thalamus following MD?

Answer 41

Yes- changes to the dLGN which links to L4

Question 42

What is required for MD to occur

Answer 42

High plasticity so OD can shift