Nervous System Development

Question 1

Neurulation

Answer 1

Formation of the neural tube
Occurs around 3 weeks
Forms from neural groove

Question 2

Primary vesicles of the brain

Answer 2

Present at week 3
1. prosencephalon
2. mesencephalon
3. rhombencephalon

Question 3

Foundational transitions include…

Answer 3

1. neural crest -> PNS
2. neural tube -> CNS
3. central canal -> ventricles in CNS
4. autonomic ganglia -> autonomic nervous system

Question 4

Sulcus limitans

Answer 4

Separates the sensory and motor areas for the posterior/caudal part of the neural tube
Relevant to the spinal cord

Question 5

Forebrain progresses to…

Answer 5

Telencephalon and diencephalon at 5 weeks
Cerebrum and thalamus, hypothalamus, and epithalamus at birth

Question 6

Midbrain progresses to…

Answer 6

Mesencephalon at 5 weeks
Midbrain at birth

Question 7

Hindbrain progresses to…

Answer 7

Metencephalon and myelencephalon at 5 weeks
Pons, cerebellum and medulla oblongata at birth

Question 8

Choroid plexis

Answer 8

Develops in week 7-15
Makes cerebral spinal fluid
Present on the interior of the brain

Question 9

Sonic hedgehog (SHH)

Answer 9

Part of the dorsal-ventral patterning
Released from the notochord

Question 10

Bone morphogenic proteins (BMPs)

Answer 10

Part of the dorsal-ventral patterning
Released from the roof plate
Part of anterior-posterior patterning
Released from posterior side
Controlled by Pax6

Question 11

Morphogens

Answer 11

Compounds that signal via receptors to control gene expression

Question 12

Fibroblast growth factors (FGFs)

Answer 12

Part of the anterior-posterior patterning
Released from anterior side
Controlled by EMx2

Question 13

Netrin

Answer 13

Chemoattractant in the spinal chord
Secreted by the floor plate
Attracts axons to extend to the ventral floorplate and cross to the contralateral side

Question 14

DCC

Answer 14

Receptor for netrin

Question 15

Slit

Answer 15

Repellant present on the floorplate of the spinal cord
Axons are insensitive until expression of the Robo receptor (expressed upon crossing the midline)

Question 16

Robo

Answer 16

Receptor expressed when axons cross the midline of the spinal cord
Causes axon repulsion from slit and netrin

Question 17

Ephrin A

Answer 17

Chemorepellent responsible for axonal projections from retina to tectum
Engaged in forward signaling and reverse signaling

Question 18

Ephrin A forward signaling

Answer 18

Ephrin A binds to EphA on growth cone
Leads to repulsion of the axon

Question 19

Ephrin A reverse signaling

Answer 19

EphA binds Ephrin A expressed on growth cone
Leads to repulsion of the axon

Question 20

Synaptic pruning

Answer 20

Process that occurs at the end of maturation (after 1st year of life)
Allows for refinement of synapses

Question 21

Hebb’s rule

Answer 21

Neurons that fire sequentially with strengthen their synapse

Question 22

Spina Bifida

Answer 22

Neural tube doesn’t close, leaving a gap
Leads to a lack of vertebral formation and herniation in the spinal cord
Location and size of the opening indicates the severity and phenotype
Caused by a folic acid deficiency

Question 23

Holoproencephaly

Answer 23

Secondary vesicles don’t form properly (failed separation of prosencephalon from diencephalon and telencephalon)
Leads to defects in the formation of longitudinal fissures

Question 24

Cerebral Palsy

Answer 24

Abnormal development of motor areas (motor cortex, cerebellum)
Caused by lack of oxygen, injury, genetics
Symptoms: lack of muscle coordination, weakness, and tremors

Question 25

Fetal Alcohol Syndrome

Answer 25

Caused by alcohol consumption during pregnancy
Results in disruption of corpus callosum, hippocampus, caudate, and cerebellum formation