Chapter 9: Neural Development

Question 1

zygote stage

Answer 1

after conception, cells of the fertilized egg start to multiply. lasts for two weeks

Question 2

neural plate

Answer 2

primitive neural tissue
formation induced by the underlying organizer tissue

Question 3

what are the organizer tissues of the neural plate?

Answer 3

ectoderm layer (develops into skin), mesoderm layer (develops into muscle), endoderm layer (develops into internal organs)

Question 4

neural tube

Answer 4

formed by the neural plate folding over

Question 5

what does the neural tube become?

Answer 5

central nervous system

Question 6

what does the neural crest become?

Answer 6

peripheral nervous system

Question 7

spina bifida

Answer 7

failure of the neural tube to close completely, resulting in a portion of the spinal cord remaining uncovered.
can usually be corrected at birth, in severe cases baby will not walk

Question 8

anencephaly

Answer 8

front end of the neural tube does not close leading to failure of the forebrain to develop.
baby usually only lives for a few days

Question 9

when does the embryo stage occur

Answer 9

onward from 14 days until the fetal stage

Question 10

what can stem cells do?

Answer 10

replicate themselves and differentiate into any one of many types of cells

Question 11

what is found in the subventricular zone?

Answer 11

lining of neural stem cells surrounding the ventricles

Question 12

what are progenitor cells?

Answer 12

multi-potent cells

Question 13

what can a progenitor cell become?

Answer 13

a neuroblast or a glioblast

Question 14

what are the two types of cell migration out of the subventricular zone?

Answer 14

radial migration (straight outward)
tangential migration (side to side; less defined)

Question 15

how many layers are there in the neocortex?

Answer 15

6, with the 6th layer being populated first

Question 16

what do radial glial cells do?

Answer 16

lay a path outward to other parts of the brain, allowing cells to migrate along them

Question 17

what is the purpose of reelin?

Answer 17

a signalling protein that signals cells to aggregate exactly where they need to be

Question 18

what are the steps of cell aggregation?

Answer 18

1. cells reach where they’re supposed to be and start to tangentially migrate to fit into their exact spot
2. differentiate into different cells when they are in their proper spot

Question 19

what do neuoblasts turn into?

Answer 19

interneurons or pyramidal neurons

Question 20

what do glialblasts turn into?

Answer 20

oligodendroglia or astrocytes

Question 21

how do young neurons start to mature?

Answer 21

1. axonal growth: extend their axons to nearby targets to initiate synapse formation (develops quickly)
2. dendritic growth: sprouts dendrites to provide surface area for synapses with other cells (develops slowly)

Question 22

what does chemical signalling allow for?

Answer 22

allows growth to occur precisely

Question 23

synaptogenesis

Answer 23

the genesis of new synapses

Question 24

growth cones

Answer 24

develop the early pathways (such as the visual pathway)

Question 25

fasciculation

Answer 25

lay down a signaling pathway for the growth cones to follow and re-enforce

Question 26

filopodia

Answer 26

extend outward to detect chemical signals

Question 27

when does the fetal stage occur?

Answer 27

onward from 9 weeks until birth

Question 28

what occurs during the fetal stage?

Answer 28

new neurons and glia continue to be born, migrate, differentiate, and mature

Question 29

when does the human brain begin to develop gyri and sulci?

Answer 29

8 months into development

Question 30

postnatal development

Answer 30

the brain continues to develop after birth in response to environmental stimuli, neurons continue to mature, and myelination is taking place

Question 31

synaptic pruning

Answer 31

occurs throughout childhood to create stronger pathways and better connections by reducing unnecessary connections