Plasticity and regeneration

Question 1

What is embryonic neurogenesis?

Answer 1

• neurogenesis that occurs during embryonic development
• neurogenesis is the formation of new neuronal cells

Question 2

What is neurogenesis?

Answer 2

• process by which new neurons are formed in the brain

Question 3

Neurogenesis occurs during pregnancy, when does it start and end?

1. week 3 to week 12
2. week 3 to week 24
3. week 3 to week 28
4. week 3 to week 38

Answer 3

3. week 3 to week 28
   * occurs during neurulation at week 3 of gestation up to 28 weeks

Question 4

What are the main steps of embryonic neurogenesis, also called neurulation?

Answer 4

1 - trilaminer germ disk forms (ecto, meso and endoderm)

2 - mesoderm cells differentiate into notochord (cartilage precursor)

3 - notochord begins neurulation, causing cells in ectoderm to differentiate and form the neural plate

4 - neural plate dips forming a groove with neural folds, that come together forming a neural tube and leave the ectoderm

5 - cells on dorsal side of neural tube differentiate into neural crests

6 - neural crests will form the PNS and other cells

Question 5

Neural crest cells formed from the dorsal part of the neural tubes are a temporary group of cells that break away from the neural tube. These cels are then able to form a diverse number of cells. What are some of the most important cells and tissues the neural crest cells go on to form?

Answer 5

• melanocytes
• craniofacial cartilage and bone
• smooth muscle
• peripheral and enteric (GIT) neurons and glia (schwann cells)
• adrenal medullary cells

Question 6

What are neural stem cells?

1. cells located within ventricular zone for neurogenesis
2. cells involved in PNS only
3. cells involved in CNS only
4. cells able to self renew and differentiate into any cell type

Answer 6

4. cells able to self renew and differentiate into any cell type

Question 7

What are progenitor stem cells?

1. cells that are programmed to differentiate into one cell type
2. cells able to differentiate as many times as required
3. cells able to differentiate a limited number of times and limited cell types
4. cells able to differentiate a limited number of times but unlimited cell types

Answer 7

3. cells able to differentiate a limited number of times and limited cell types

• specialised form of stem cell
• able to differentiate a limited number of times
• able to differentiate into a limited number of cell types

Question 8

When we compare cells from the blastocyst to neural crest cells, which one is a stem cell and which one is a progenitor cell?

Answer 8

• blastocyst = stem cell
• neural crest = progenitor cell (limited cells type and differentiation)
• progenitor cells come from stem cells

Question 9

Neural stem cells form what?

Answer 9

• ALL cell types in nervous system (neurons and glia cells)
• able to self renew

Question 10

What is the difference between symmetric and asymmetric cell division in neuronal stem cells?

Answer 10

• symmetric (same) = produces 2 differentiated or 2 stem cells
• asymmetric (not the same = produces a stem and a progenitor cell

Question 11

Where are neuronal stem cells initially found after 3 weeks of embryonic development?

1. neuronal tube
2. ectoderm
3. mesoderm
4. gonadal ridge

Answer 11

1. neuronal tube

Question 12

When stem cells differentiate do they become differentiated cells straight away or something else?

Answer 12

• they become a progenitor cell first
• this is an intermediate stage before becoming a specialised cell type following a stimulus to differentiate

Question 13

Neural crest cells are a specific type of cell that can differentiate into a variety of different cells. What is a key characteristic of this cell type though?

Answer 13

• migratory cells
• able to move to different parts of the body, like melanocytes in the skin

Question 14

What are neuroblast cells?

1. naive neural crest cell
2. naive neuronal cells
3. naive schwann cells
4. naive glial cells

Answer 14

2. naive neuronal cells
   - neuroepithelial cells that began in the neural tube
   - intermediate step from a neuronal stem cell before it differentiates into a specialised cell in the CNS

Question 15

Neuroblast cells (naive neuronal cells) are an intermediate step from a neuronal stem cell before it differentiates into a specialised cell in the CNS. What are the 2 main groups these cells become from neuronal stem cells in the CNS?

1. neuroblasts and schwann cells
2. neuroblasts and glioblasts
3. glioblasts and schwann cella
4. glioblasts and choroid cells

Answer 15

2. neuroblasts and glioblasts

• neuroblasts (uni, bi, multi polar neurons etc..)
• glioblasts (astrocytes, oligodendrocytes, microglial)

Question 16

The notch receptor of the delta notch signalling pathway regulates differentiation of progenitor cells towards neurons. Cells contains notch receptors on their membranes, one of which is called delta, which when bound to a ligand will promote intracellular pathways that trigger its differentiation into a specific type of cell. What does this signalling pathway promote the formation of?

1. neurons
2. oligodendrocytes
3. astrocytes
4. microglia

Answer 16

3. astrocytes

Question 17

The notch receptor of the delta notch signalling pathway regulates differentiation of progenitor cells towards neurons. Cells contains notch receptors on their membranes, one of which is called delta, which when bound to a ligand will promote intracellular pathways that trigger its differentiation into a specific type of cell. This signalling pathway promotes the formation of of astrocytes, whilst inhibiting what 2 other cells?

1. neurons and oligodendrocytes
2. neurons and microglia
3. microglia and oligodendrocytes
4. microglia and choroid cells

Answer 17

1. neurons and oligodendrocytes

Question 18

We know that in the delta-notch signalling pathway, that notch promotes the formation of astrocytes but is able to inhibit neurons and oligodendrocytes. In order for neurons to preferentially develop, especially in the cortex, what has to happen?

1. notch agonist called numb allows neurons to develop
2. notch antagonist called numb allows neurons to develop
3. notch antagonist called numb allows oligodendrocytes to develop
4. notch agonist called numb allows microglia cells to develop

Answer 18

2. notch antagonist called numb allows neurons to develop
   - numb is a protein that inhibits notch, inhibiting astrocyte formation and promoting neurons

Question 19

What are filopodia?

1. cillia in CNS aimed to promote CSF fluid movement
2. thin extensions of dendrites
3. thin membrane protrusions acting as cell probe to sample surrounding tissues
4. thin membrane protrusions that fix the cell to a specific spot

Answer 19

3. thin membrane protrusions acting as cell probe to sample surrounding tissues
   - they are the tips of axons

Question 20

What are lamellipodia?

1. cillia in CNS aimed to promote CSF fluid movement
2. thin extensions of dendrites
3. thin membrane protrusions acting as cell probe to sample surrounding tissues
4. actin cytoskeleton formed form microtubules of developing neurons assisting with motility

Answer 20

4. actin cytoskeleton formed form microtubules of developing neurons assisting with motility

Question 21

What are growth cones?

1. cillia in CNS aimed to promote CSF fluid movement
2. actin supported extension of developing neuronal cells facilitating growth
3. thin membrane protrusions acting as cell probe to sample surrounding tissues
4. actin cytoskeleton formed form microtubules of developing neurons assisting with motility

Answer 21

2. actin supported extension of developing neuronal cells facilitating growth

Question 22

How many layers of neurons does the cerebral cortex have?

1. 2
2. 4
3. 6
4. 8

Answer 22

3. 6
   - aprox 2-4 mm in thickness

Question 23

What does the term cortical refer to in relation to neurogenesis?

Answer 23

• precursor for cerebral cortex
• the most outer layer of the brain that is grey matter as its cell bodies

Question 24

In cortical development, which is the precursor for the cerebral cortex (the outer most layer of the brain that is grey matter, as per image below) where do the newly formed neurons begin?

1. ventricular zone within ventricles of the brain
2. thalamus
3. cerebellum
4. pons

Answer 24

1. ventricular zone within ventricles of the brain

Question 25

In cortical development, which is the precursor for the cerebral cortex (the outer most layer of the brain that is grey matter, as per image below), newly formed neurons begin in the ventricular zone (ventricles of the brain). Which other type of glial cells facilitate this migration from the ventricular zone to the cortical plate? 1. microglia 2. oligodendrocytes 3. astrocytes 4. radial glial cells

Answer 25

4. radial glial cells

Question 26

Radial glial cells facilitate the movement of neurons from the ventricular zone to the cortical zone. What are radial glial cells? 1. bipolar-shaped progenitor cells 2. fully differentiated glial cells 3. pseudopolar shaped progenitor cells 4. naive astrocytes

Answer 26

1. bipolar-shaped progenitor cells - responsible for producing all of the neurons in the cerebral cortex (most outer part of the brain)

Question 27

Radial glial cells provide the scaffolding for new neurons to migrate from the ventricular zone to the cortical zone. Neurons are able to use part of their intracellular machinery that allows them to use the scaffolding laid down by the radial glial cells and move up to cerebral layers like a spider. What is this called? 1. radial glial osmosis 2. radial glial translocation 3. radial glial migration 4. radial glial extension

Answer 27

3. radial glial migration

Question 28

What does the inside out model of cortical development lead to?

Answer 28

- formation of the 6 layers of the cerebral cortex

Question 29

Why is the inside-out model of cortical development called the inside out model?

Answer 29

- neurons migrate from ventricular zone (VZ) to layer 1 (closest to the skull) - the next neurons from the VZ have to migrate to level 2 - this continues up to level 6 (closest to ventricular zone)

Question 30

Infant neurogenesis begins at the ventricular zone, but where does adult neurogenesis occur? 1. sub-ventricular zone and hippocampus 2. ventricular zone and hippocampus 3. sub-ventricular zone and thalamus 4. ventricular zone and thalamus

Answer 30

1. sub-ventricular zone and hippocampus * specifically dentate gyrus in hippocampus * olfactory also has some adult neurogenesis

Question 31

What cell type does adult neurongenesis begin as?

Answer 31

- neuronal stem cell - neuroblasts

Question 32

In adult neurongenesis they begin as neuronal stem cells and then into neuroblasts in the sub ventricular zone of the lateral ventricles. Once the neuroblasts have differentiated into immature neurons what 2 places do they migrate to? 1. cerebral cortex and thalamus 2. cerebral cortex and hippocampus 3. cerebral cortex and olfactory bulb 4. cerebral cortex and cerebellum

Answer 32

3. cerebral cortex and olfactory bulb

Question 33

Once newly formed neurons have migrated along the rostral migratory stream to the olfactory bulb, what happens to them?

Answer 33

- integrated into the already formed neuronal network - migration is guided by physical, molecular and electricl signals

Question 34

When new neurons have been formed and they try to merge with an already established network. In order for them to move to where they should move to, what 2 signalling methods are used 1. chemoattraction and hormonal 2. chemorepulsion and hormonal 3. chemoattraction and chemorepulsion 4. chemorepulsion and rejection

Answer 34

3. chemoattraction and chemorepulsion * chemoattraction - new neuron moves up the concentration gradient of a chemoattractant * chemorepulsion - new neuron is repelled by a specific chemoattractant

Question 35

When new neurons have been formed and they try to merge with an already established network, there are a number of different things they can do to merge. The 2 most important for us are chemoattraction (attracted to a specific stimuli) and and chemorepulsion (repelled by a specific stimulus). Why are these important?

Answer 35

- important chemical axon guidance ques where newly formed axons will integrate into exisiting neuronal networks

Question 36

Commissural neurons are one of the tracts that facilitate communication between the left and right hemisphere and cross the spinal cord, such as the corpus callosum. Why is chemoattraction and chemorepulsion important in commissural neurons?

Answer 36

- tells neurons where they are needed - netrin is a chemiattractant a signalling molecule on the floor plate of the neural tube. So it tells some neurons to connect to it, and others not to

Question 37

When we are born the body produces too many neurons in early embryonic development. As there are too many what happens to these excess neurons?

Answer 37

- apoptosis (programmed cell death)

Question 38

When we are born the body produces too many neurons in early embryonic development. As there are too many neurons they undergo apoptosis (programmed cell death). Is this random?

Answer 38

- no - neurotrophins regualte this process

Question 39

When we are born the body produces too many neurons in early embryonic development. As there are too many neurons they undergo apoptosis (programmed cell death) which is controlled by neurotrophins. What are 3 important neutrotrophins?

Answer 39

1 - neutrophins growth factor (NGF) 2 - brain derived growth factor (BDNF) 3 - fibroblast growth factor (FGF)

Question 40

Neurons are very sensitive to damage, however, some do posses the ability to regenerate. Do the neurons of the CNS or PNS possess a better regenerative capacity?

Answer 40

- PNS

Question 41

Neurons are very sensitive to damage, however, some do posses the ability to regenerate. The neurons of the PNS possess a better regenerative capacity than those in the CNS. What is the main cell that drives this regenerative capacity? 1. macrophages 2. cytokines 3. neutrophils 4. schwann cells

Answer 41

4. schwann cells mainly - macrophages help by removing debris

Question 42

Neurons are very sensitive to damage, however, some do posses the ability to regenerate. The neurons of the PNS possess a better regenerative capacity. Schwann cells are the main cell that drive this regenerative capacity. What are the 2 main roles the schwann cells play in regeneration in the PNS? 1. removal of debris and stimulate axonal growth 2. re-myelineate axons and stimulate axonal growth 3. removal of debris and re-myelineate axon 4. stimulate immune response and stimulate axonal growth

Answer 42

2. re-myelineate axons and stimulate axonal growth

Question 43

Neurons are very sensitive to damage, however, some do posses the ability to regenerate. The neurons of the CNS possess a poor regenerative capacity. Why is this? 1. macrophages and reactive astrocytes do poor job and lay down collagen 2. macrophages and reactive microglia do poor job and lay down collagen 3. macrophages and reactive oligodendrocytes do poor job and lay down collagen 4. macrophages and reactive astrocytes do poor job, scars form and poor re-myelination

Answer 43

4. macrophages and reactive astrocytes do poor job, scars form and poor re-myelination

Question 44

Neurons are very sensitive to damage, however, some do posses the ability to regenerate. The neurons of the CNS possess a poor regenerative capacity due to the formation of a glial scar. Although they cannot regenerate well, what are they good at? 1. rapid neurogenesis 2. rapid cell differentiation 3. rapid neuronal cell mitosis 4. synaptic plasticity (re-organising)

Answer 44

4. synaptic plasticity (re-organising)

Question 45

The critical period is an important time point in neural development, what is it?

Answer 45

- time during postnatal neural development - neuronal plasticity is dependent on environmental signals

Question 46

The **_critical period_** is an important time point in neural development, which is the time during postnatal neural development where neuronal plasticity is dependent on environmental signals. Is there just one critical period?

Answer 46

- no - the time is variable - can be multiple critical periods, such as binocular vision, language skills

Question 47

**_Critical periods_** are characterised by what? 1. increased hormones levels 2. increased growth factor levels 3. increased neuronal plasticity 4. increased excitatory neurons

Answer 47

3. increased neuronal plasticity - more adaptation occurs due to stimulus to our brains

Question 48

If a specific function such as speech is not learned sufficiently at a **_critical period_** what could this lead to?

Answer 48

- poor speech or lack of speech function - example of eyesight in the image below, but the same principle

Question 49

Does cortical plasticity increase or decrease with age?

Answer 49

- decreases with age

Question 50

If someone had a few fingers amputated what could happen in the brain, specifically in the post-central gyrus

Answer 50

* cortical plasticity would occur * skin near the amputation would receive similar stimulus as previously felt in the fingers

Question 51

The somatosensory cortex is responsible for receiving and processing sensory information from across the body. Are all parts of the somatosensory cortex that are linked with different senses the same size?

Answer 51

* no * size of somatosensory cortex is dependent on complexity of functions * face and mouth have a large somatosensory cortex * hips or foot have a small somatosensory cortex area as their functions are limited

Question 52

The somatosensory cortex is responsible for receiving and processing sensory information from across the body. Different body parts parts have different volumes in the somatosensory cortex, which is linked to the complexity of that body part. Why is this important?

Answer 52

- greater density of sensory receptors have a higher cortical plasticity - so hands would have greater cortical plasticity than the feet

Question 53

New memories are dependent on the development of new neuronal cells, called neurogenesis. Specifically where does the development occur in the brain? 1. dentate gyrus in the hippocampus 2. dentate gyrus in ventricles 3. dentate gyrus in the cerebellum 4. dentate gyrus in the cerebral cortex layer 1

Answer 53

1. dendate gyrus within the hippocampus

Question 54

The computational theories of memory suggests what in relation to memory?

Answer 54

- new memories require cortical plasticity - new memories = new neuron formation in dendate gyrus of the hippocampus - older memories are encoded in the pre exisitng neuronal network