CNS Development

Question 1

when does brain development begin

Answer 1

3rd week post conception - continues into adolescence and beyond

Question 2

what to genes determine when it comes to brain development

Answer 2

• correct sequence and evolution of the brain (conception - neuronal proliferation -neuronal migration - reorganisation)
• development of dendritic and axonal interconnections
• development of synapses, receptors and neurotransmitters

Question 3

what parts of the intrauterine environment can effect brain development

Answer 3

• maternal health and disease
• Insults which may be continuous throughout pregnancy (alcohol, infection)
• placental function and fetal nutrition

Question 4

What parts of the extrauterine environment can effect brain function

Answer 4

physical factors eg. nutrition, environmental toxins

emotional and social factors eg. neglect and lack of stimulation

exposure to drugs, alcohol and other related substances

Question 5

how long is the embryonic period

Answer 5

8 weeks (conception - 8 weeks)

Question 6

what is inside the uterus in the embryonic phase

Answer 6

a 2 layered embryo made up of the epiblast and hypoblast

Question 7

where do cells migrate through in the embryo

Answer 7

the primitive streak

Question 8

what happens during gastrulation

Answer 8

development of 3 layers

ectoderm - hair, skin, nails
mesoderm - muscles, bone, cartilage
endoderm - gut and respiratory system

Question 9

What is the first well defined structure to form and when

Answer 9

the neural tube - forms around 20-27 days

Question 10

what leads to neural tube formation

Answer 10

neural progenitor cells from the neural place form a grove, which then forms a tube, which then goes on to form the neural crest

Question 11

what is the ventricular zone

Answer 11

the outside of the neural tube - lined with neural progenitors

Question 12

what does the hollow structure inside the neural tube become

Answer 12

the Ventricular system

Question 13

what does the central channel of the neural tube become

Answer 13

the spinal cord

Question 14

what are the primary brain vesicles and when do they occur

Answer 14

occur at 3/4 weeks

prosencephalon (forebrain)
mesencephalon (midbrain)
Rhombencephalon (hindbrain)

Question 15

what are the secondary brain vesicles and when do they occur

Answer 15

occur at 5 weeks

Tencephalon 
Diencephalon 
Mesencephalon 
Metencephalon 
Myelencephalon

Question 16

what is neural patterning in the embryo

Answer 16

complex and continuous refinement of neural pattern development

Question 17

what is the neocortex

Answer 17

part of the brain concerned with vision and hearing

Question 18

what does high EMX2 and low PAX6 lead to in the neocortex

Answer 18

neural progenitor cells differentiated into visual cortex neutrons

Question 19

what does low EMX2 and high PAX6 lead to in the neocortex

Answer 19

neural progenitor cells differentiate into motor neurons

Question 20

when is the fetal period

Answer 20

week 9/10 till birth

Question 21

what does the brain look like before it folds into a sulcal gyral pattern

Answer 21

smooth

Question 22

when do the primary sulci develop

Answer 22

8-26 weeks

Question 23

when do secondary sulci develop

Answer 23

30-35 weeks

Question 24

when do tertiary sulci develop

Answer 24

week 36 onwards into post natal and early infancy

Question 25

how to neural progenitor cells in the ventricular zones divide to begin with

Answer 25

symmetrically - division produces 2 progenitor cells

Question 26

how do neural progenitor cells in the ventricular zone divide later

Answer 26

asymmetrically eg. cell division produces one progenitor cell and one neuron

Question 27

where do the neurons produces in the ventricular zones migrate to

Answer 27

the developing neocortex

Question 28

3 methods of neural migration

Answer 28

Somal translocation radial glial guides tangential migration and signalling pathways

Question 29

what happens to neurons once they reach their target cortical region

Answer 29

they form axons and dendrites so they can communicate with each other

Question 30

what's the function of axons

Answer 30

transmit signals from neurons | develop synapses when connected to other neurons long bit

Question 31

What's the function of dendrites

Answer 31

gather information and transmit it to the neuron | multiple dendrites form around the neuron star bit lol

Question 32

where do neurons in the ventricular zones migrate to in postnatal brain development

Answer 32

olfactory bulb | dentate gyrus of the hippocampus

Question 33

what is mylelination

Answer 33

when oligodendrocyte progenitor cells develop processes which wrap around axons forming a myelin sheath

Question 34

what are the functions of the myelin sheath

Answer 34

greatly increased axonal conduction maintains axonal integrity and survival maintains neuronal size and axonal diameter

Question 35

at what age does most myelination occur

Answer 35

first 2 years

Question 36

why is postnatal experiences needed for brain development

Answer 36

to allow for mature organisation - learning from experiences leads to synaptic pruning

Question 37

what developmental tasks are adolescents aiming to achieve

Answer 37

- establishing nurturing and intimate relationships - developing identity - future perspectives - independence - self confidence - self control - social skills

Question 38

what happens to the brain in adolescence

Answer 38

many synapses are eliminated theres an increase in white matter volume changes in neurotransmitter systems

Question 39

what are grey and white matter

Answer 39

grey matter - contains cell bodies/where the synapses are white matter - axons connecting different parts of grey matter together

Question 40

how do hormones affect the teenage brain

Answer 40

rise of steroid hormones in puberty affects the brain as it is full of steroid receptors. This causes restructuring and permanent reorganising

Question 41

what happens when there is monocular visual deprivation in early post natal life

Answer 41

one eye is blocked so the other eye takes over the visual cortex area usually occupied by the blocked eye

Question 42

what is anencephaly

Answer 42

absence of a major portion of the brain, skull and scalp due to a neural tube defect

Question 43

what is spina bifida

Answer 43

gap in the spine due to baby's spinal cord not developing

Question 44

what is holoprosencephaly

Answer 44

failure of development of the procephalon (embryological forebrain) to sufficiently divide into the double lobes of the cerebral hemisphere

Question 45

what is hypomyelination

Answer 45

inherited condition causing abnormally low amounts of myelination

Question 46

what is dysmyelination

Answer 46

malformed and defective myelin sheath

Question 47

what is demyelination

Answer 47

destruction of myelin that surrounds axon - example is MS

Question 48

what does the PLP1 gene encode for

Answer 48

a transmembrane proteolipid protein which is a prominent myelin protein (located on X chromosome)

Question 49

what is Pelixaeus-Merzbacher disease

Answer 49

mutation in PLP1 gene causing shortened life span. Presents in infancy with hypotonia and cognitive impairment

Question 50

What is spastic paraparesis 2

Answer 50

a less severe mutation of the PLP1 gene which manifests as spastic paraperisis with or without CNS involvement

Question 51

how does malnutrition affect brain development

Answer 51

impacts brain growth and volume impacts myelination lack of energy due to malnutrition can lead to a lack of postnatal experiences