Neuroplasticity

Question 1

What makes something plastic?

Answer 1

1. something that has a structure

2. structure can change

Question 2

Any [long term] change in the nervous system that is not periodic; Duration of more than a few seconds; Combination of both flexibility and stability

Answer 2

Neuroplasticity

Question 3

Decreased response to a repeated stimulus that doesn’t matter; Involves changes in neurotransmitter release (strength of synaptic connections); Reversible

Answer 3

Habituation

Question 4

How can habituation be reversed?

Answer 4

1. Stop repeating the stimulus
2. Change the stimulus
3. Sensitizing stimulus

Question 5

How could you use habituation?

Answer 5

Use of techniques and exercises to decrease the neural response to a stimulus; repeated stimulus to create habituation

Question 6

More long-lasting, persistent; involves changes in strength of synaptic connections

Answer 6

learning and memory

Question 7

What are the 3 main types of learning and memory?

Answer 7

1. Motor memory
2. Verbal memory
3. Emotional memory

Question 8

Procedural memory; the more you do a task, the better you will be

Answer 8

Motor memory

Question 9

Remembering items that can be spoken or written; repetition can help

Answer 9

Verbal memory

Question 10

Memory for associations of emotions with specific places, people, etc.

Answer 10

Emotional memory

Question 11

When starting to learn a task, _______ of the brain involved. With repetition the number of brain regions [increase/decrease]. When the the task is learned _______ of the brain show activity during performance of a task.

Answer 11

Large and diffuse areas; decrease; distinct regions (only regions involved)

Question 12

Long-term memory requires

Answer 12

1. the synthesis of new proteins

2. growth of new synaptic connections

Question 13

Proposed mechanism to explain long-term memory

Answer 13

Long-term potentiation

Question 14

Where does long-term potentiation occur?

Answer 14

Hippocampus (pt of temporal low)

Question 15

The hippocampus is important for processing _________. Bilateral damage to the hippocampus results in an inability to form new ____________.

Answer 15

Verbal memory; verbal memories

Question 16

Repetitive stimulation of hippocampus will [increase/decrease] the responses to the stimulus. how doe one accomplish this in treatment?

Answer 16

increase;

1. single stim - measure response
2. repeated stem
3. single stem - measure response (larger)

Question 17

What are the effects of long term potentiation

Answer 17

1. Increases in synaptic activity
2. Increased effectiveness of neuron firing
3. Synapses that are effective become more effective (Neurons that fire together, wire together)

Question 18

What happens to astrocytes in long-term potentiation?

Answer 18

increase in astrocyte-neuron conctacts

Question 19

What are the mechanisms of LTP?

Answer 19

1. Conversion of ‘silent synapses’ into active synapses

2. Postsynaptic membrane is remodeled to form new dendritic spines and synapses

Question 20

What happens when the cell body of a neuron is injured?

Answer 20

If severe enough, it will kill the cell (dead neurons are not replace)

Question 21

What happens when the axon of a neuron is injured?

Answer 21

1. Will cause degenerative changes, but will not necessarily kill the neuron
2. If axon severed, the two ends will seal; has a proximal section of the axon, which is attached to the cell body, and a distal section, which continues to the presynaptic terminal

Question 22

What will happen to the distal section of the axon after injury?

Answer 22

1. “Wallerian degeneration” - section away from body degenerates
2. Glial cells will clean up (schwann cells in PNS)
3. Postsynaptic cell will show some degenerative changes (trans-synaptic degeneration, some may die)

Question 23

What happens to the proximal section of the axon after injury?

Answer 23

Central chromatolysis (dissolution of Nissle substance [rough ER]; cell body may die

Question 24

Does age at the time of injury matter with neuronal cell injury?

Answer 24

Yes, children recover better; recovery decreases with age

Question 25

Denervated target is reinnervated by branches of intact axons; occurs in polio

Answer 25

Collateral sprouting

Question 26

Target and axon both damaged, Target dies, and Injured axon sends out collaterals to new targets; new axons sprout to new targets

Answer 26

Regenerative sprouting

Question 27

Schwann cells make growth factors that contribute to recovery of peripheral axons; Recovery is better with a crush injury compared to a cutting injury; more prevalent in PNS

Answer 27

Functional regeneration

Question 28

Factors that exist in PNS that improve recover and facilitate regeneration

Answer 28

Nerve Growth Factor (produced by schwann cells)

Question 29

What are the factors that contribute to the CNS's inability to regenerate?

Answer 29

1. No Schwann cells producing NGF 2. Oligodendrocytes inhibit growth of neurons 3. Incomplete cleanup of cellular debris by microglia

Question 30

What problem can occur during regenerate?

Answer 30

Sprouting may innervate inappropriate targets - Motor neurons may innervate different muscles (These movements are usually short-lived, and the individual relearns muscle control) - Can also see confusion of sensory modalities

Question 31

What changes occur in synapses after injury?

Answer 31

1. Local edema and recovery of synaptic effectiveness 2. Denervation hypersensitivity 3. Synaptic hyper effectiveness 4. Unmasking of silent synapses

Question 32

Why can edema cause a neuron to stop working?

Answer 32

Edema can put pressure on axons or cell bodies and cause the neuron to become inactive (function can return after pressure is relieved)

Question 33

Occurs when there is damage to presynaptic terminals; The postsynaptic cells lose all or some of their synaptic inputs; Postsynpatic neurons (and muscles) respond by producing more receptors (will respond to NTMs released by other axons)

Answer 33

Denervation hypersensitivity

Question 34

Occurs when only some of the axon branches of a neuron are damaged; The presynaptic cell body still makes the usual amount of neurotransmitter, so each terminal receives more neurotransmitter, and more neurotransmitter is released at each synapse

Answer 34

Synaptic hypereffectiveness

Question 35

How does unmasking of silent synapses occur?

Answer 35

1. Disinhibition of silent synapses 2. Many synapses in the central nervous system appear to be non-functional (silent) 3. An injury to pathways in the brain can unmask these synapses and they can become functional

Question 36

What chemicals are important for changes in silent synapses?

Answer 36

1. NMDA receptors 2. Ca++ ions 3. Neurotrophins (growth factors) 4. Substance P 5. Nitric oxide 6. Changes in subtypes of sodium ion channels

Question 37

What happens to the area of cortex corresponding to a particular part of our body we used more?

Answer 37

Increases in size

Question 38

What are complications of neuronal reorganization?

Answer 38

1. May see referred sensations after an amputation (phantom limb sensation, phantom pain); Stimuli that are applied to one area of the body are felt to occur in a different part of the body; A touch to the chin may be felt as if it were applied to a missing fifth finger 2. Functional reorganization may also be a factor in some chronic pain syndromes, where pain persists after the injury heals

Question 39

_______ of somatosensory pathways causes the increased release of inhibitory neurotransmitters. If there is _____ of sensory pathways, the cortex can become more sensitive to weak stimuli.

Answer 39

Overstimulation; understimulation

Question 40

What can promote axonal growth to increase stimulation?

Answer 40

Reduced activity

Question 41

Supports survival of sensory neurons, basal forebrain cholinergic neurons, and mesencephalic dopaminergic neurons; May be of use in local treatment of neurodegenerative disorders (Parkinson’s Disease); May be of use in protecting motor neurons in patients with motor neuropathies and ALS

Answer 41

Brain-derived neurotrophic factor (BDNF)

Question 42

May have a role in treating Alzheimer’s Disease (protects cholinergic neurons in primates), Diabetic neuropathy, and Chemotherapy-induced neuropathies; May promote neuroplasticity

Answer 42

Nerve growth facto (NGF)

Question 43

Patient is made to use the affected body part; patient has an injury to the CNS; mostly done with patients with strokes, extended to patients with CP

Answer 43

Forced Activity (AKA constraint induced moment therapy)

Question 44

According to a study conducted by Kozlowski et al, what is the effect of making the animal use the affected area in the sensorimotor cortex right away?

Answer 44

The injury will become more severe; Long-term behavioral deficits (Poor limb placement, Decreased response to sensory stimulation, Defective use of limb for postural support)

Question 45

According to a study conducted by Nudo et al, what is the the effect of waiting 5 days after a lesion in the sensorimotor cortex before making the animal do activity?

Answer 45

The lesion reduced in size and prevented loss of function in the area adjacent to lesion

Question 46

In human studies in pts with strokes, pts' unaffected limbs were restrained and were made to use their affected side 8 hours a day 1-2 times per week. What were its results?

Answer 46

Motor functioning were improved

Question 47

Why could constraint therapy work?

Answer 47

Pt is affected with learned helplessness - brain learns a body part doesn't work - even if some function returns, pts still won't use it because they have learned it doesn't work

Question 48

"too much of a good thing"; happens when brain cells are killed (ischemia or TBI); large amounts of glutamate is released and excite NMDA receptors, causing a large Ca influx, resulting in the neuronal death

Answer 48

Excitotoxicity