B7.002 CNS Development and Brain Anatomy

Question 1

when does neural development take place

Answer 1

begins 3 weeks post conception
continues throughout lifetime
after 20 primarily degenerative changes

Question 2

what starts nervous system development

Answer 2

induction of the neural plate on day 18 by notochord signals

Question 3

what is spina bifida

Answer 3

failure of the neural tube to close, results in failure of vertebral column to form correctly
can happen anywhere along the spine
nervous system can escape
causes damage to spinal cord and associated peripheral nerves

Question 4

spina bifida occulta

Answer 4

no external evidence

neuro structures in the correct place, vertebrae just missing

Question 5

meningocele

Answer 5

meninges escape via outpouching, but spinal cord remains in correct location

Question 6

myelomeningocele

Answer 6

worst form of spina bifida

cord and meninges exit column resulting in neuro deficits

Question 7

what is the notochord

Answer 7

structure just ventral to the neural plate
group of mesodermal cells that send chemical signal to the overlying ectoderm cells to begin differentiation into the neural plate (induction)

Question 8

why do neural folds develop

Answer 8

due to proliferation nd elongation of epithelial cells in the neural plate

Question 9

neural groove

Answer 9

formed as the neural folds move toward each other

located on the dorsal surface of the embryo

Question 10

neural tube formation

Answer 10

neural plate cells pinch off to form neural tube, located underneath the ectoderm of the embryo
occurs first in the center of the embryo and extends rostral and caudal

Question 11

neuropores

Answer 11

openings at each end of the developing neural tube

failure to close caudal one = spina bifida

Question 12

anencephaly

Answer 12

failure of rostral neuropore closure and tissue differentiation
results in death

Question 13

epidemiology of spina bifida

Answer 13

1/1000 births

Question 14

screening for spina bifida

Answer 14

AFP - alpha fetoprotein
ultrasounds
amniocentesis
xray, MRI, or CT of spinal column

Question 15

treatment / prevention of spina bifida

Answer 15

surgery corrects vertebral and spinal problems

folic acid can reduce incidence (400 mg per day)

Question 16

neural crest cells

Answer 16

cells that originate lateral to the neural plate
pinched off during formation of the neural tube
migrate between ectoderm and neural tube

Question 17

examples of neural crest derivatives

Answer 17

dorsal root ganglia
some neurons and all glial cells within the sensory ganglia of V, VII, IX, and X ganglia
sympathetic, parasympathetic, and enteric ganglia
chromaffin cells of adrenal medulla
pia and arachnoid
Schwann cells
melanocytes

Question 18

what are neurocristopathies

Answer 18

diverse class of pathologies that arise from defects in tissues derived from the embryonic neural crest cell lineage

Question 19

zones/layers of neural tube

Answer 19

innermost: ventricular zone
intermediate zone (mantle)
outermost: marginal zone

Question 20

where does mitosis occur in the neural tube

Answer 20

ventricular zone (innermost)

Question 21

discuss connections to the external and internal limiting membranes of the neural tube during development

Answer 21

most of the time, proliferating cells are connected to both membranes
during M phases, nuclei of dividing cells move toward internal limiting membrane and lose connection with external limiting membrane
this is why mitotic figures are in the ventricular zone

Question 22

what happens to daughter cells after cell division takes place in the neural tube

Answer 22

move back toward external limiting membrane (interkinetic nuclear migration)

Question 23

what happens after the last cell division of neurons

Answer 23

migrate out of ventricular layer and come to rest in intermediate (mantle) zone
neuronal birthday

Question 24

is there neurogenesis in the adult brain

Answer 24

not really

vast majority occurs during embryogenesis in neural tube

Question 25

effect of Zika virus

Answer 25

targeted developing neurons in pregnant women, causing microcephaly in newborns due to lack of neurons

Question 26

appearance of neural tube at 4 weeks gestation

Answer 26

3 vesicle stage - prosencephalon (forebrain) - mesencephalon (midbrain) - rhombencephalon (hindbrain)

Question 27

appearance of neural tube at 5 weeks gestation

Answer 27

``` 5 vesicle stage (rostral and caudal swellings divide into 2) forebrain: -telencephalon (cerebral hemisphere) -diencephalon (thalamus and hypothalamus) mesencephalon (midbrain) hindbrain: -metencephalon (pons) -myelencephalon (medulla) ```

Question 28

what genes govern segmentation of the neural tub

Answer 28

homeobox genes

Question 29

planes of section

Answer 29

horizontal / axial (like looking into feet of a person lying on a table) coronal (crown like) sagittal (like drawing back an arrow through the body)

Question 30

dual meaning of dorsal

Answer 30

in head, superior | in body, posterior

Question 31

dual meaning of ventral

Answer 31

in head, inferior | in body, anterior

Question 32

most rostral part of a human adult

Answer 32

forehead region

Question 33

central sulcus

Answer 33

divides frontal and parietal lobes

Question 34

precentral gyrus

Answer 34

primary motor cortex | voluntary movement

Question 35

postcentral gyrus

Answer 35

primary somatosensory cortex | receiver information from sensory receptors in skin

Question 36

lateral (sylvian) fissue

Answer 36

very deep | separates frontal and temporal lobes

Question 37

occipital lobe

Answer 37

most caudal lobe

Question 38

parieto-occipital sulcus

Answer 38

divides parietal and occipital lobes

Question 39

parts of telencephalon

Answer 39

cerebral hemispheres - cerebral cortex - subcortical white matter - basal ganglia - basal forebrain nuclei

Question 40

parts of diencephalon

Answer 40

thalamus hypothalamus epithalamus

Question 41

parts of mesencephalon

Answer 41

cerebral peduncles midbrain tectum midbrain tegmentum

Question 42

parts of metencephalon

Answer 42

pons | cerebellum

Question 43

parts of myelencephalon

Answer 43

medulla

Question 44

formation of flexures

Answer 44

occur along the length of the neural tube as proliferation continues eventually telencephalon expands so that it covers the more caudal derivatives of the neural tube

Question 45

lumen of neural tube

Answer 45

becomes ventricular system in the adult brain

Question 46

what influences differentiation into sensory/motor functions

Answer 46

induction factors in specific regions of the neural tube dorsal = sensory = alar plate ventral = motor = basal plate

Question 47

formation of gray matter of spinal cord

Answer 47

post mitotic neurons leave proliferative zone, causing an increase in size of the mantle later this region becomes the gray matter (dorsal and ventral horns)

Question 48

formation of white matter of spinal cord

Answer 48

composed of axons of local neurons within gray matter as well as axons from neurons carrying ascending and descending information

Question 49

stain for neuronal cell bodies

Answer 49

Nissl Stain

Question 50

ganglion

Answer 50

group of neuronal cell bodies in the periphery | neural crest derivatives

Question 51

nucleus

Answer 51

group of neuronal cell bodies in the CNS

Question 52

afferent

Answer 52

information flowing toward the CNS | -sensory axons

Question 53

efferent

Answer 53

information flowing away from the CNS | -motor axons

Question 54

ascending

Answer 54

information flow to cerebral cortex (sensory)

Question 55

descending

Answer 55

information flow toward spinal cortex (motor)

Question 56

how do pathways develop?

Answer 56

trophic factors neuronal migration synapse elimination (plasticity) maturation of neuronal connection

Question 57

how do neuron #s match target size

Answer 57

neurons are produced in excess, some die to match the target size due to production of trophic factors by targets

Question 58

where does synapse elimination occur

Answer 58

cellular level | competition for innervation

Question 59

how many layers are present in the gray matter?

Answer 59

6

Question 60

how do motor and sensory areas of gray matter differ

Answer 60

motor: bigger cells in deeper layer sensory: more cells in middle region

Question 61

layer 1

Answer 61

outermost molecular layer contains mainly neuropil

Question 62

layers 2 and 3

Answer 62

2: external granular 3: external pyramidal generally smaller pyramidal neurons primarily corticocortical connections

Question 63

layer 4

Answer 63

internal granular layer rich in stellate neurons with locally ramifying axons in the primary sensory cortices, these neurons receive input from the thalamus, the major sensory relay from the periphery

Question 64

layer 5 and 6

Answer 64

5: ganglionic 6: multiform contain pyramidal neurons whose axons leave the cortex prominent in motor areas

Question 65

function of radial glia in cortex development

Answer 65

neurons use radial glial cells to help with migration into outer layers chemical cues also help with this

Question 66

formation of correct connections between groups of neurons

Answer 66

in some cases, neurons make connections early when in close proximity and reel out processes as growth of surrounding structures pushes them apart in other cases, neurons use cues to grow to a target and synapse on the correct postsynaptic partner

Question 67

synaptic plasticity

Answer 67

modification of connections between neurons following damage or in the course of learning

Question 68

maturation of cellular architecture and connectivity of neurons

Answer 68

connections multiply and finalize over a long period of time