Development of the nervous system

Question 1

When does human brain development begin?

Answer 1

3rd week post conception and continues well into late adolescence/ early adulthood

Question 2

What do genes determine in the development of the brain?

Answer 2

Correct sequence and evolution of the brain from conception to neural proliferation, migration and reorganisation
Development of dendritic and axonal interconnections
Determine the development of synapses, receptors and neurotransmitters

Question 3

What can influence nervous system development intrauterine?

Answer 3

Maternal health and disease
Insults which may be continuous throughout pregnancy - alcohol exposure, cytomegalovirus
Placental function and fetal nutrition

Question 4

What can influence nervous system development extrauterine?

Answer 4

Physical factors such as nutrition, environmental toxins
Emotional and social factors e.g. neglect and lack of stimulation
Exposure to drugs, alcohol and other related substances

Question 5

What is considered the embryonic period?

Answer 5

Conception - 8 weeks

Question 6

What makes up the embryo?

Answer 6

Epiblast and hypoblast
Primitive streak and primitive node - cells migrate through the streak then rostral-caudal migration determined by nodal signalling

Question 7

What is gastrulation?

Answer 7

Formation of germ layers - ectoderm, mesoderm and endoderm

Question 8

What will ectodermal tissue become?

Answer 8

Skin
Nails
Hair
Neural

Question 9

What will mesodermal tissue become?

Answer 9

Muscle
Bone
Cartilage
Vascular system

Question 10

What will endodermal tissue become?

Answer 10

Gut

Respiratory system

Question 11

What is the first well defined neural structure to form?

Answer 11

Neural tube

Question 12

When does the neural tube form?

Answer 12

Day 20-27

Question 13

What lines the neural tube?

Answer 13

Neural progenitors - ventricular zone

Question 14

What will the hollow centre of the tube become?

Answer 14

Ventricular system and central channel of the spinal cord

Question 15

What will the anterior tube become?

Answer 15

Brain

Question 16

What will the caudal tube become?

Answer 16

Spinal cord

Question 17

What are the characteristics of the surface of the brain at week 9?

Answer 17

Initially smooth (lissencephalic) and gradually develops its folded appearance (sulcal and gyral pattern)

Question 18

What occurs during weeks 8-26 of foetal brain development?

Answer 18

Primary sulci e.g. longitudinal fissure, sylvian cingulate, parieto-occipital and calcarine, temporal

Question 19

What occurs during weeks 30-35?

Answer 19

Secondary sulci

Question 20

What occurs during weeks 36-post natal period and early infancy?

Answer 20

Tertiary sulci

Question 21

Why are gyri and sulci needed?

Answer 21

To accommodate the proliferating neuronal populations

Question 22

Where do neurones migrate to?

Answer 22

Neocortex

Question 23

What occurs when neurones reach their target cortical regions?

Answer 23

They develop processes which allow them to communicate and transmit information between neurones

Question 24

What do axons do?

Answer 24

Transmit signals from neurones
Guidance molecules determine path
Synapses develop when connected with another neuron

Question 25

What do dendrites do?

Answer 25

Gather info and transmit to neurones | Multiple dendrites from arbors around the neuron

Question 26

What percentage of neurones will die?

Answer 26

50% mostly prenatally

Question 27

What percentage of synaptic connections will be eliminated?

Answer 27

50%, postnatally and ongoing throughout life

Question 28

What occurs postnatally in brain development?

Answer 28

Postnatal proliferation and migration | Myelination

Question 29

What parts of the brain will develop post-natally?

Answer 29

Olfactory bulb Dentate gyrus of the hippocampus Glial progenitors become oligodendorocytes and astrocytes

Question 30

What cells will develop myelin sheaths?

Answer 30

Oligodendrocytes

Question 31

What is the purpose of a myelin sheath?

Answer 31

``` Increase axonal conduction dramatically Maintain axonal integrity Survival Neuronal size Axonal diameter ```

Question 32

What way will axons become myelinated?

Answer 32

Sequential manner from bottom to top and from back to front

Question 33

What impact does experience have on the development of the brain?

Answer 33

Essential for emergence of normal neocortical patterns When input is lacking, the brain areas develop differently Specific patterns of development reflect the kinds of input the infant and child receive Enrichment and deprivation

Question 34

What are the developmental tasks of the adolescence?

Answer 34

``` Establish nurturing and intimate relationships Development of identity Future perspectives Self-confidence Self control Social skills ```

Question 35

What occurs in the brain during adolescence?

Answer 35

Many synapses are eliminated Increase in white matter volume Changes in neurotransmitter systems

Question 36

What type of receptors is the brain full of?

Answer 36

Steroid receptors - therefore the rising gonadal hormone concentrations in teenage years affect the brain

Question 37

What differing effects do estrogen and androgens have on the brain?

Answer 37

Oestrogens make girls more prone to stress | Androgens make boys more resilient to stress

Question 38

What insults to the brain can occur?

Answer 38

Insults within first few weeks not compatible with life: neural tube formation, brain vesicles, migrational disturbances

Question 39

What problems can occur with neural tube formation?

Answer 39

Anencephaly | Spina bifida

Question 40

What is holoprosencephaly?

Answer 40

Failure of brain vesicles to form

Question 41

What are the different disorders of myelination?

Answer 41

Hypomyelination Dysmyelination Demyelination

Question 42

What is the PLP1 gene?

Answer 42

Encodes a transmembrane protein, the predominant myelin protein in the CNS. It is responsible for compaction, stabilization and the maintenance of myelin sheaths, oligodendrocyte development and axonal survival

Question 43

Where is the PLP1 gene located?

Answer 43

X chromosome

Question 44

What is the most severe PLP1 gene?

Answer 44

Pelizaeus-merzbacher

Question 45

What will pelizaeus-merzbacher present as?

Answer 45

``` Nystagmus Hypotonia Cognitive impairment Severe spasticity Ataxia ```

Question 46

What impact will malnutrition have on brain development?

Answer 46

Brain growth and volume Myelination Lack of energy and deprivation - lack of postnatal stimulation and experiences