Brain Development in Paediatrics

Question 1

When does human brain development commence?

Answer 1

3rd week post conception

Question 2

Which intrauterine factors may negatively impact the development of the nervous system?

Answer 2

1. Maternal health and disease
2. Insults (physical or infection)
3. Placental or nutritional issues

Question 3

Which extrauterine factors may negatively impact the development of the nervous system?

Answer 3

1. Nutrition or environmental toxins
2. Emotional and social factors
3. Exposure to alcohol or drugs

Question 4

How long does the embryonic period last?

Answer 4

Conception until gestational week 8

Question 5

How many layers is the embryo comprised of during the embryonic period and what are they called?

Answer 5

2

Epiblast and hypoblast

Question 6

The primitive streak is a transient structure that marks what?

Answer 6

The start of gastrulation

Question 7

What happens in gastrulation?

Answer 7

The formation of the trilaminar embryonic disc, which is comprised of the three germ layers (ectoderm, mesoderm and endoderm)

Question 8

What is the role of the primitive node?

Answer 8

Determines migration of cells into cleft where cells form 3 layers

Question 9

Which adult tissues form from the ectoderm?

Answer 9

1. Skin
2. Nails
3. Hair
4. Neural tissue

Question 10

Which adult tissues form from the mesoderm?

Answer 10

1. Muscle
2. Bone
3. Cartilage
4. Vascular system

Question 11

Which adult tissues form from the endoderm?

Answer 11

1. Gut
2. Respiratory

Question 12

Between which days of development is the neural tube expected to develop?

Answer 12

20-27

Question 13

Which cells is the neural crest derived?

Answer 13

Neural progenitor cells

(from neural plate)

Question 14

Failure of the neural groove, and then tube, to close results in what?

Answer 14

Neural tube defects

Question 15

Which cells line the inside of the neural tube and what is this zone called?

Answer 15

Neural progenitor cells

Ventricular zone

Question 16

The hollow centre of the neural tube will develop into what?

Answer 16

1. Ventricular system
2. Central channel of spinal cord

Question 17

Which aspect of the neural tube will become the brain?

Answer 17

Anterior/rostral tube

Question 18

Which aspect of the neural tube becomes the spinal cord?

Answer 18

Caudal tube

Question 19

What are the three primary brain vesicles in a three to four week embryo?

Answer 19

1. Prosencephalon (forebrain)
2. Mesencephalon (midbrain)
3. Rhombencephalon (hindbrain)

Question 20

How many secondary brain vesicles develop in a five week embryo?

Answer 20

5

Question 21

Which two signalling molecules influece the development of the neocortex?

Answer 21

1. EMX2
2. PAX6

Question 22

A high PAX6 concentration and low EMX2 concentration induce progenitor cells to develop into what?

Answer 22

Motor neurones

Question 23

A high EMX2 concentration and low PAX6 concentration induce progenitor cells to develop into what?

Answer 23

Visual cortical neurones

Question 24

What is required in the foetal period in order to accomodate the proliferating neural cell populations?

Answer 24

Development of gyri and sulci

Question 25

How are neurones produced during the foetal period?

Answer 25

Neuronal progenitor cells (in ventricular zone) divide initially symmetrically to produce two neural progenitor cells Asymmetrical division follows producing one progenitor cell and one **neurone**

Question 26

When neurones are produced, where do they migrate?

Answer 26

Developing neocortex

Question 27

In terms of brain development what are two of the main processes which occur postnatally?

Answer 27

1. Continued proliferation and migration 2. Myelination

Question 28

In which sequential manner does myelination occur in the brain postnatally?

Answer 28

1. Bottom to top 2. Front to back

Question 29

For how long does myelination occur postnatally?

Answer 29

* Mainly in first 2 years * Continues into 20s

Question 30

Physical maturation of the brain in adolescent years is associated with what?

Answer 30

Rising gonadal hormone concentrations

Question 31

What is holoprosencephaly?

Answer 31

A cephalic disorder in which the prosencephalon (the forebrain of the embryo) fails to develop into two hemispheres

Question 32

In terms of myelin, what is the PLP1 gene responsible for?

Answer 32

Encodes the most predominant transmembrane **proteolipid protein** in myelin Responsible for compactation, stabilisation and maintenance of **myelin sheaths**, development of **oligodendrocytes** and **axonal survival**

Question 33

Where is the PLP1 gene located?

Answer 33

X chromosome

Question 34

What is the most severe condition associated with a PLP-1 mutation?

Answer 34

Pelizaeus-Merzbacher disease

Question 35

When does Pelizaeus-Merzbacher disease present and how?

Answer 35

Infancy or early childhood 1. Nystagmus 2. Hypotonia 3. Cognitive impairment 4. Progresses to severe spasticity and ataxia 5. Short life span